Background Statement for SEMI Draft Document #5188A
NEW STANDARD: GUIDE TO EVALUATE THE EFFICACY OF SUB-15
nm FILTERS USED IN ULTRAPURE WATER (UPW) DISTRIBUTION
SYSTEMS
Notice: This background statement is not part of the balloted item. It is provided solely to assist the recipient in
reaching an informed decision based on the rationale of the activity that preceded the creation of this Document.
Notice: Recipients of this Document are invited to submit, with their comments, notification of any relevant
patented technology or copyrighted items of which they are aware and to provide supporting documentation. In this
context, “patented technology” is defined as technology for which a patent has issued or has been applied for. In the
latter case, only publicly available information on the contents of the patent application is to be provided.
Background Statement
Optical Particle Counters (OPCs) used in high volume semiconductor manufacturing have reached a practical
measurement limit of 40 nm, with a counting efficiency of only a few percent at this size. However, even at 40 nm,
the size detection is above the half pitch of current technology semiconductor devices, rendering the metrology
unable to confirm the presence of potentially “killer particles” at the required sizes. At the same time, the size of the
particles to be controlled in UPW is approaching the capability of the filtration used. Lack of metrology capability
and marginal filtration efficiency substantially increase the risk to the next generation of the wafer manufacturing
technology. UPW ITRS has suggested a risk mitigation strategy based on off-line validation of the filter
performance. Until the particle metrology gap is solved, this approach minimizes the risk to the wafer and allows
conformance with the current ITRS requirements.
Current methods of filter performance characterization using 50-200nm PSL (polystyrene latex) spheres and OPCs,
and extrapolating performance to 5-15nm is inadequate for guaranteeing filter performance at the extrapolated size.
The fact that the filters’ performance is marginal in this range makes it impossible to reliably extrapolate results. A
new method of quantifying filter performance is required for filters with a pore size of 5-15 nm
This document is a guide prepared to standardize the recommended conditions under which the filter performance
can be tested. It also provides reference for the preparation of the test report and a methodology for data
interpretation.
It is important to emphasize that the methodology documented in the proposed standard has numerous limitations,
described below. However, the task force believes that it is adequate to the goal this document is called to address:
risk mitigation of the particle control. The purpose of this document is to standardize the filter test conditions to
allow comparison of different filter performances. It is expected that use of this guide will generate more data that
will allow improving the document in future revisions. Not having such a guide or having adequate particle
metrology poses significant risk to the advanced semiconductor manufacturing (based on the information from ITRS
and SEMATECH.
References
ITRS documents:
http://www.itrs.net/Links/2011ITRS/2011Chapters/2011Yield.pdf
http://www.itrs.net/Links/2011ITRS/2011Tables/Yield_2011Tables.xlsx
Reference SEMATECH Report:
Abbas Rastegar, Arun John Kadaksham, Matt House, Byunghoon Lee, Jae Choi, Masahiro Kishimoto, Aron J.
Cepler, Thomas Laursen, Takeya Shimomura: “EUV Mask and Blank Cleaning Requirements for 16 nm HP node”.
SEMATECH Albany September 2010
Review and Adjudication Information*
Task Force Review
UPW Filtration Efficiency TF
Monday, October 29, 2012
3:00 PM to 5:00 PM, Pacific Time
SEMI Headquarters
3081 Zanker Rd.
City, State/Country: San Jose, California/USA, 95134
Slava Libman (Air Liquide)
Leader(s):
Group:
Date:
Time & Timezone:
Location:
Standards Staff:
Michael Tran (SEMI NA)
408.943.7019
mtran@semi.org
Committee Adjudication
NA Liquid Chemicals Committee
Tuesday, October 30, 2012
1:00 PM to 4:00 PM, Pacific Time
SEMI Headquarters
3081 Zanker Rd.
San Jose, California/USA, 95134
Frank Flowers (FMC)
Frank Parker (ICL)
Michael Tran (SEMI NA)
408.943.7019
mtran@semi.org
*This meeting’s details are subject to change, and additional review sessions may be scheduled if necessary.
Contact the task force leaders or Standards staff for confirmation.
Telephone and web information will be distributed to interested parties as the meeting date approaches. If you will
not be able to attend these meetings in person but would like to participate by telephone/web, please contact
Standards staff.
Semiconductor Equipment and Materials International
3081 Zanker Road
San Jose, CA 95134-2127
Phone: 408.943.6900, Fax: 408.943.7943
DRAFT
SEMI Draft Document #5188A
NEW STANDARD: GUIDE TO EVALUATE THE EFFICACY OF SUB-15
nm FILTERS USED IN ULTRAPURE WATER (UPW) DISTRIBUTION
SYSTEMS
1 Purpose
1.1 This document is a recommended guide to evaluate the efficacy of filter elements used in Ultrapure Water
(UPW) fluid streams, providing particle control as risk mitigation for particle contamination on the wafer.
1.2 Due to the lack of adequate on-line particle detection metrology at the particle sizes addressed by this guide,
however off-line filter performance testing can be used to validate filter retention efficiency. Off-line filter
performance testing will help mitigate the risks related to particle control in flowing UPW streams that make contact
with silicon wafers.
1.3 This document provides a guide to the test method to evaluate filter elements used in Ultrapure Water (UPW)
fluid streams.
1.4 This document is a guide rather than a standard. Additional data is necessary to correlate the results tested in the
procedure using high challenge particle concentrations with the actual filter’s performance to evaluate particle
behavior under much lower particle concentrations in real world UPW. That is to say, in the method described in
this guide, filters are challenged at high particle concentrations not representative of real-world conditions because
current particle-detection metrology cannot detect low particle concentrations.
2 Scope
2.1 This guide applies to UPW-system final filters and other UPW distribution filters intended for use in
semiconductor manufacturing tools and ancillary equipment.
2.2 This guide applies to advanced Semiconductor facilities requiring control of the UPW particles from 5-15 nm.
The guide may also be used for large particles not covered by existing particle-detection metrology.
2.3 Four aspects in evaluating filter performance are considered in this guide:
2.3.1 Ability of the filter to retain influent particles is assessed with a particle challenge test. The filter is tested
under single pass filtration of water or challenge particle solution – with no recirculation applied.
2.3.2 Possible contribution of particles by the filter is evaluated during initial rinse of the filter.
2.3.3 Filter performance stability is addressed by repeating the performance test throughout the operating lifetime of
the filter. Different representative filters from the same group of filters are tested during filter life time in order to
confirm the frequency of the filter change out.
NOTE 1: Major defects in the filter are detected using an integrity test specified by the filter supplier.
2.3.4 Initial filter cleanliness.
2.4 This guide describes procedures for measuring filter particle retention while using UPW as the test media. UPW
parameters, for the intents and purposes of this guide, is defined in §7.6.
2.5 This guide uses commercially available colloidal silica with a mean particle size of 5-15 nm. Using Polystyrene
Latex spheres (PSL) as a filter challenge does not work at the 5-15 nm size range because the PSL size distribution
is too broad and using white spherical plastic beads is an unrealistic challenge for filter testing. Colloidal silica is a
superior challenge material because it is commercially available (and inexpensive) in the 5-15 nm size range.
Colloidal silica has a relatively narrow size distribution and has lower interaction with filter material; therefore it is
primarily removed by a filter’s sieving mechanism.
2.6 The filter-performance evaluation procedure described in this guide uses a combination of grab-sample lab
analysis and in-situ liquid particle measurement (using an aerosol particle detection technique).
This is a Draft Document of the SEMI International Standards program. No material on this page is to be construed as an official or adopted Standard or Safety Guideline.
Permission is granted to reproduce and/or distribute this document, in whole or in part, only within the scope of SEMI International Standards committee (document
development) activity. All other reproduction and/or distribution without the prior written consent of SEMI is prohibited.
Page 1
Doc. 5188A  SEMI
LETTER (YELLOW) BALLOT
Document Number: 5188A
Date: 2/9/2016
Semiconductor Equipment and Materials International
3081 Zanker Road
San Jose, CA 95134-2127
Phone: 408.943.6900, Fax: 408.943.7943
DRAFT
NOTICE: SEMI Standards and Safety Guidelines do not purport to address all safety issues associated with their
use. It is the responsibility of the users of the Documents to establish appropriate safety and health practices and
determine the applicability of regulatory or other limitations prior to use.
3 Limitations
3.1 This guide specifies challenge test conditions that will enhance the particle measurement sensitivity of the test
and standardize the testing environment. However, actual performance under normal operating conditions may vary.
3.2 Filters tested under the conditions specified in this guide may vary in their performance from the filters used in
the actual UPW system. Consistency of the filter manufacturing may also affect test results therefore testing more
than one filter and conducting a statistical analysis should be considered.
3.3 The test procedure is destructive; the filter cannot be returned into operation.
3.4 A large number of parameters affect the outcome of the test described in this guide therefore it is challenging to
maintain perfectly consistent conditions from one test to another. The test results are a qualitative rather than a
quantitative assessment of filter performance.
3.5 The challenge test conditions use a particle concentration significantly higher than the concentration typically
expected in the UPW feed into the final filters. Therefore the performance of the filters under typical UPW
conditions is expected to be better than their performance in the test. This document should not be used for
establishing the rating of a filter by suppliers, but rather for the end user assessment of the filter performance.
3.6 This guide can be used to test smaller filters than those typically used in production-scaled UPW applications.
For valid test outcomes, small filters should be verified by the filter supplier to have the same performance
characteristics as their larger counterparts, such as ultra-filters (UF) or greater numbers of single typical cartridge
filter elements (0.25 m size) connected together. For the validity of the results, the flow rate through the tested filter
should be scaled to the actual operating conditions.
3.6.1 Material purity and potential leaching of dissolved contaminants are not addressed by this guide. SEMI F57
does not address this issue for final filters therefore the end user may decide to consider such testing when selecting
different types of filters.
3.7 The accuracy of the data generated by the challenge test described in this guide is limited to the accuracy of the
analytical techniques utilized.
3.8 The experimental work conducted as part of the preparation of this document suggested significant effect of the
challenge particle concentration to the filter retention efficiency (see Appendix 5). As a result, this guide uses a
minimum filtration-efficiency requirement of 50% as a reference only, assuming that filters, which do not provide
50% particle removal pose a higher risk of not removing particles at the 5 – 15 nm size under normal conditions of
the UPW system. The required efficiency of the filtration depends on the end user’s process needs and will be
finally determined by the end user.
3.9 The required efficiency for particle removal is to be confirmed by the end users based on the process need.
3.10 Filter operational conditions used in the test (such as flux, differential pressure, specific surface area, etc.) are
limited to the information provided by the filter supplier. The end user should compare the conditions of the test to
those used in the actual application to ensure that the results of the tests are representative.
3.11 Tolerances in the figures used in the test protocol (such as flow rate, concentration, etc.) are assumed to be +/10% unless otherwise stated.
3.12 Minimum size or number of the tested filters should provide sufficient flow rate to adequately operate
metrology used in the test. To provide the minimum turbulence required for consistent performance, a Reynolds
Number >5,000 is required in all main process piping.
3.13 Particle loading rate and concentration are fixed in the specified test conditions to prevent excessive
monolayers of colloidal silica from developing on the filter surface. The end user should consider whether the flux
used for the test represents the actual conditions of the filter operation in the full-scale application.
This is a Draft Document of the SEMI International Standards program. No material on this page is to be construed as an official or adopted Standard or Safety Guideline.
Permission is granted to reproduce and/or distribute this document, in whole or in part, only within the scope of SEMI International Standards committee (document
development) activity. All other reproduction and/or distribution without the prior written consent of SEMI is prohibited.
Page 2
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LETTER (YELLOW) BALLOT
Document Number: 5188A
Date: 2/9/2016
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Phone: 408.943.6900, Fax: 408.943.7943
DRAFT
3.14 The guide is limited to the conditions of ambient temperature of UPW. Performance of the filters under
HUPW conditions has been excluded from this guide due to limited data available. The HUPW filter testing is
expected to be included in a future revision of this document.
4 Referenced Standards and Documents
4.1 SEMI Standards
SEMI E49-1104 (Reapproved 1211) — Guide for High Purity and Ultrahigh Purity Piping Performance,
Subassemblies, and Final Assemblies
SEMI F57 — Specification for Polymer Materials and Components Used in Ultrapure Water and Liquid Chemical
Distribution Systems
SEMI F61-0301 (Reapproved 0309) — Guide for Ultrapure Water System Used in Semiconductor Processing
NOTICE: Unless otherwise indicated, all documents cited shall be the latest published versions.
5 Units
5.1 Parts per million (ppm) is equivalent to μg/mL or mg/L, where 1 L approximately equals 1 kg.
5.2 Parts per billion (ppb) is equivalent to ng/mL or μg/L, where 1 L approximately equals 1 kg.
5.3 Parts per trillion (ppt) is equivalent to pg/mL or ng/L, where 1 L approximately equals 1 kg.
5.4 Micrometer is a unit of length equal to one millionth of a meter, or one thousandth of a millimeter.
6 Terminology
6.1 Abbreviations and Acronyms
6.1.1 General terms and acronyms used in this standard are listed below and may be defined in SEMI F61.
6.1.1.1 OPC — Optical Particle Counter
6.1.1.2 NRM — Nonvolatile Residue Monitor
6.1.1.3 TOC — Total Organic/Oxidizable Carbon
6.1.1.4 PSDA — Particle Size Distribution Analyzer
6.1.1.5 UPW — Ultra Pure Water
6.1.1.6 HUPW — Hot UPW
6.1.1.7 DMA — Differential Mobility Analyzer
6.1.1.8 ITRS — International Technology Roadmap for Semiconductors
6.1.1.9 ICP-MS — Inductively Coupled Plasma Mass Spectrometry
6.1.1.10 PSL — Polystyrene Latex
6.2 Definitions
6.2.1 Background — the average particle and other contaminant concentrations in the test system reported by OPC,
PSDA, NRM, dissolved silica and total silica analyses. Background is reported when UPW flows through the test
skid and spool piece (after rinsing the test skid components and spool piece to a steady-state of background
contamination). Background includes contributions from the UPW and test skid components.
6.2.2 Test Skid (see Figure 1) — the system providing filter-evaluation test analysis. The test skid includes piping,
filter housing, filter elements, flow meters, pressure gauges, valves, regulators, sample ports, etc.
This is a Draft Document of the SEMI International Standards program. No material on this page is to be construed as an official or adopted Standard or Safety Guideline.
Permission is granted to reproduce and/or distribute this document, in whole or in part, only within the scope of SEMI International Standards committee (document
development) activity. All other reproduction and/or distribution without the prior written consent of SEMI is prohibited.
Page 3
Doc. 5188A  SEMI
LETTER (YELLOW) BALLOT
Document Number: 5188A
Date: 2/9/2016
Semiconductor Equipment and Materials International
3081 Zanker Road
San Jose, CA 95134-2127
Phone: 408.943.6900, Fax: 408.943.7943
DRAFT
Tested Filter Unit
Concentrated
Particles
Metering pump
V-8
P1
V-3
From UPW
supply
V-1
Static
Mixer
P-2
To Reclaim (to be
used outside of UPW)
V-7
V-9
V-2
V-4
V-15
V-5
V-10
V-11
V-12
V-13
V-14
V-16
FI-1
Sample 2
V-22
V-6
Sample 1
V-17
DMA
Optional Sample Port
for on-line validation of the
challenge solution quality
FI-2
V-18
OPC
FI-3
NRM
FI-4
TOC (optional)
FI-5
To Drain
19
Optional reject
line for testing
crossflow filters
V-20
V-21
FI-6
Figure 1
General Test Schematic Diagram
7 Test Skid Configuration
7.1 The test skid should be enclosed in an ISO Class 7 (per current revision of ISO 14644, roughly equivalent to
FED STD 209E Class 10,000), or better, environment. Procedures necessary to maintain ISO Class 7, or better,
when handling any part of the test system, or during testing, should be followed. Deviation from this requirement
may be approved by the end user, while maintaining the intent of the clean environment. If more exacting testing is
required, end users may need to follow more stringent testing requirements.
7.2 Ultrapure, low-particle-generating, low shedding piping systems should be used in all wetted flow paths from
the UPW source to the filtration test skid to ensure that the requirements of §7.6 are maintained. The
recommendations within SEMI E49 should be considered when designing and assembling the system.
7.3 The test skid should be designed and built according to the requirements listed in Appendix 1.
7.4 The method of injection is flexible provided a clean environment can be ensured. Reversing the flow in the
injection port is necessary to prevent stagnation and contamination.
7.5 Protect the test system from excessive vibration which could lead to high particle-background counts.
7.6 The UPW should be in compliance with the following minimum requirements:
7.6.1 Minimum operating pressure downstream from the test skid should be 20 psig (138 kPa) during testing.
7.6.2 Temperature of 23 5C (77  9F).
7.6.3 Resistivity 18 MΩ•cm at 25°C (77°F).
This is a Draft Document of the SEMI International Standards program. No material on this page is to be construed as an official or adopted Standard or Safety Guideline.
Permission is granted to reproduce and/or distribute this document, in whole or in part, only within the scope of SEMI International Standards committee (document
development) activity. All other reproduction and/or distribution without the prior written consent of SEMI is prohibited.
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Document Number: 5188A
Date: 2/9/2016
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Phone: 408.943.6900, Fax: 408.943.7943
DRAFT
7.6.4 TOC < 5 ppb.
7.6.5 Total Silica < 0.5 ppb.
7.6.6 Dissolved Silica < 0.1 ppb.
7.6.7 NVR < 0.1 ppb.
7.6.8 The maximum recommended particle-concentration background level is 0.05 particle/ml (>0.1 m).
7.7 Before beginning the test, filter components should be prepared, installed, and pre-wetted in accordance with
the filter supplier recommendations.
7.8 Ensure that the instrumentation (flow meters and pressure gauges or transducers) is calibrated in accordance
with the manufacturers’ procedures and frequency.
7.9 The components under test and the plumbing between the components under test should be oriented to limit
bubble entrapment because bubbles cause metrology errors. The filters should be positioned vertically and the test
skid should be vented to prevent gas accumulation and bubble formation.
7.10 A data-acquisition system is required to monitor filter performance. The data acquisition system should be able
to capture particle data at least once per minute.
7.10.1 To test the background level of the test skid, configure the test skid in accordance with Figure 2 and insert a
spool piece or empty filter housing as needed (the background test provides baseline measurement data needed for
the initial rinse-up reference). When testing cartridge filters, it is recommended to use an empty filter housing
instead of a spool piece.
7.11 For rinse testing, configure the test stand in accordance with Figure 3 and insert a test filter component or test
filter assembly.
This is a Draft Document of the SEMI International Standards program. No material on this page is to be construed as an official or adopted Standard or Safety Guideline.
Permission is granted to reproduce and/or distribute this document, in whole or in part, only within the scope of SEMI International Standards committee (document
development) activity. All other reproduction and/or distribution without the prior written consent of SEMI is prohibited.
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Doc. 5188A  SEMI
LETTER (YELLOW) BALLOT
Document Number: 5188A
Date: 2/9/2016
Semiconductor Equipment and Materials International
3081 Zanker Road
San Jose, CA 95134-2127
Phone: 408.943.6900, Fax: 408.943.7943
DRAFT
Empty Housing or Spool Piece
Concentrated
Particles
Metering pump
V-8
P1
V-3
From UPW
supply
V-1
Static
Mixer
P-2
To Reclaim (to be
used outside of UPW)
V-7
V-9
V-2
V-4
V-15
V-5
V-10
V-11
V-12
V-13
V-14
V-16
FI-1
Sample 2
V-22
V-6
Sample 1
V-17
DMA
Optional Sample Port
for on-line validation of the
challenge solution quality
FI-2
V-18
OPC
FI-3
NRM
FI-4
TOC (optional)
FI-5
To Drain
19
Optional reject
line for testing
crossflow filters
V-20
V-21
FI-6
Figure 2
Background Test Configuration
This is a Draft Document of the SEMI International Standards program. No material on this page is to be construed as an official or adopted Standard or Safety Guideline.
Permission is granted to reproduce and/or distribute this document, in whole or in part, only within the scope of SEMI International Standards committee (document
development) activity. All other reproduction and/or distribution without the prior written consent of SEMI is prohibited.
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Doc. 5188A  SEMI
LETTER (YELLOW) BALLOT
Document Number: 5188A
Date: 2/9/2016
Semiconductor Equipment and Materials International
3081 Zanker Road
San Jose, CA 95134-2127
Phone: 408.943.6900, Fax: 408.943.7943
DRAFT
Tested Filter Unit
Concentrated
Particles
Metering pump
V-8
P1
V-3
From UPW
supply
V-1
Static
Mixer
P-2
To Reclaim (to be
used outside of UPW)
V-7
V-9
V-2
V-4
V-15
V-5
V-10
V-11
V-12
V-13
V-14
V-16
FI-1
Sample 2
V-22
V-6
Sample 1
V-17
DMA
Optional Sample Port
for on-line validation of the
challenge solution quality
FI-2
V-18
OPC
FI-3
NRM
FI-4
TOC (optional)
FI-5
To Drain
19
Optional reject
line for testing
crossflow filters
V-20
V-21
FI-6
Figure 3
Rinse-up Test Configuration
7.12 For the particle challenge test, configure the system in accordance with the schematic diagram shown in Figure
4.
This is a Draft Document of the SEMI International Standards program. No material on this page is to be construed as an official or adopted Standard or Safety Guideline.
Permission is granted to reproduce and/or distribute this document, in whole or in part, only within the scope of SEMI International Standards committee (document
development) activity. All other reproduction and/or distribution without the prior written consent of SEMI is prohibited.
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Doc. 5188A  SEMI
LETTER (YELLOW) BALLOT
Document Number: 5188A
Date: 2/9/2016
Semiconductor Equipment and Materials International
3081 Zanker Road
San Jose, CA 95134-2127
Phone: 408.943.6900, Fax: 408.943.7943
DRAFT
Tested Filter Unit
Concentrated
Particles
Metering pump
V-8
PI-1
PI-2
P1
V-3
From UPW
supply
V-1
Static
Mixer
To Reclaim (to be
used outside of UPW)
P-2
V-7
V-9
V-2
V-4
V-15
V-5
V-10
V-11
V-12
V-13
V-14
V-16
FI-1
Sample 2
V-22
V-6
Sample 1
V-17
DMA
Optional Sample Port
for on-line validation of the
challenge solution quality
FI-2
V-18
OPC
FI-3
NRM
FI-4
TOC (optional)
FI-5
To Drain
19
Optional reject
line for testing
crossflow filters
V-20
V-21
FI-6
Figure 4
Particle Challenge Test
8 Recommendations
8.1 A representative filter sample of the population of filters under interest should be selected for testing.
8.2 Provide material purity leach data (SEMI F57) prior to the test to demonstrate compatibility of the system with
high purity application. SEMI F57 covers all materials, but filters and the filter housings.
8.3 A minimum of 4 filter components or component assemblies should be tested to assess variability.
8.4 Component handling and packaging may impact particle test results. When testing, component handling and
packaging by the filter manufacturer should be in accordance with the typical manufacturing processes.
9 Procedures
9.1 General Procedures
9.1.1 Throughout this document, the instructions referring to the starting and stopping of UPW flow should be
carried out by using valves located at “From UPW Supply” and “To Reclaim/Drain”, as shown in Figures 1–4.
9.1.2 The steps referring to monitoring and adjusting the flow should be carried out using the flow meter and the
bypass flow meter shown in Figures 1–4. The flow through the flow meters should remain constant, as specified by
the manufacturer.
This is a Draft Document of the SEMI International Standards program. No material on this page is to be construed as an official or adopted Standard or Safety Guideline.
Permission is granted to reproduce and/or distribute this document, in whole or in part, only within the scope of SEMI International Standards committee (document
development) activity. All other reproduction and/or distribution without the prior written consent of SEMI is prohibited.
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Document Number: 5188A
Date: 2/9/2016
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Phone: 408.943.6900, Fax: 408.943.7943
DRAFT
9.1.3 This guide uses the following progression for analyses of a filter’s capability of providing particle control in
UPW applications.
System Background Level Test — establishes background level of the system to distinguish the particle contribution
from the test stand versus the components under test.
↓
Integrity Test — confirms filter integrity prior to the challenge test.
↓
Filter Element Initial Rinse-up Test — measures the particle concentration of the UPW fluid stream after UPW has
passed through the filter under test. This quantifies the initial particle contribution by the filter material.
↓
Filter Cleanliness Test — the test assesses soluble organic and inorganic contamination leached out of the prerinsed filters
↓
Filter Challenge Test — measures the ability of the filter to provide particle control after the colloidal silica
challenge solution has passed through the filter under test.
↓
Integrity Test — tests filter integrity after the challenge test.
↓
Data Analysis and Reporting — calculates the results and reports the data and test conditions.
9.2 Test Conditions
9.2.1 Given the possibility that different types, sizes, and configurations of the filters may be tested, the filter
parameters, test conditions, and results should be reported in Tables 1 and 2 for effective comparison.
Table 1 Test Conditions Report
Parameter/ Conditions
Data
Cleanliness of the skid materials (per F57 or other) – in
compliance (Yes/No)
Challenge particles (supplier, size mean, size weighting
(number or volume), lot number)
Volume of the filter housing/dummy module (between isolation
valves) Note: Useful for extraction test and dilution rates.
O-ring/gasket type
Housing material of construction
This is a Draft Document of the SEMI International Standards program. No material on this page is to be construed as an official or adopted Standard or Safety Guideline.
Permission is granted to reproduce and/or distribute this document, in whole or in part, only within the scope of SEMI International Standards committee (document
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Date: 2/9/2016
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DRAFT
Parameter/ Conditions
Data
Filter part number & serial number
Flux per unit area
Surface area
Type of the tested filter (cross flow/dead end, etc.)
Filter material of construction (membrane, support, core, cage,
caps, etc.)
Provide URL to the filter data sheet prepared by the
manufacturer
Table 2 Test Results
Integrity Test Conditions and Results
Test pressure, allowable diffusive flow, success criteria – pressure decay
Parameters
Test Duration (template – add more columns as needed – the
timelines may vary for the different steps in the test procedure)
0.5 hr
1 hr
1.5 hr
2 hrs
2.5 hr
Feed and Background Characteristics
Feed Flow Rate 1 (L/min)
Feed Temperature, C
Feed Dissolved Oxygen, ppb (if
DO controlled)
Feed dissolved and total Silica,
ppb concentration
Feed NVR, ppb
Feed Resistivity, MΩ•cm
Feed particles level, #/L, at
>0.05u (if OPC available)
Feed Pressure (psi)
Product pressure (psi)
Initial Rinse
Feed Pressure (psi)
Product pressure(psi)
This is a Draft Document of the SEMI International Standards program. No material on this page is to be construed as an official or adopted Standard or Safety Guideline.
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Flow Rate (L/min)
Product dissolved and total
Silica, ppb concentration
Feed Particles by aerosol
particle
detection
(both
concentration
and
size
distribution)
Product Particles by aerosol
particle
detection
(both
concentration
and
size
distribution)
Product NVR, ppb
Product particles level, #/L, at
>0.1μ
Particle Challenge Test
Feed Particles by aerosol
particle
detection
(both
concentration
and
size
distribution)
Product Particles by aerosol
particle
detection
(both
concentration
and
size
distribution)
Feed dissolved and total Silica,
ppb concentration
Product dissolved and total
Silica, ppb concentration
9.3 Background Test
9.3.1 Background testing is required before every test in a test series, unless testing multiple identical filters.
Example: Performing a rinse test on four individual filters when it is not necessary to re-establish the system
background between each of the filter samples, but it is necessary to achieve a stable level of the online instrument
readings within 10% of the initial background.
9.3.2 Configure the test skid in accordance with Figure 2. Install spool piece/dummy filter/empty filter housing at
the location of the filter component under test.
9.3.3 All instruments and analytical techniques included in the experimental work should be used for the
background test. The background should be tested with the same technique used for the performance analysis, as
well as using OPC, TOC, NRM, and grab-sample lab analysis.
9.3.4 Grab-sample analyses should include total and reactive Si (dissolved Si).
This is a Draft Document of the SEMI International Standards program. No material on this page is to be construed as an official or adopted Standard or Safety Guideline.
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9.3.5 Using the following instructions, clean the system by rinsing with UPW to a system background
contamination level as defined in §7.6.
9.3.5.1 Start the UPW flow through the bypass flow meter only and adjust the flow rate to the test flow rate, based
on the 0.8 cm/min face flow velocity. Maintain this flow rate for a minimum of 5 minutes in order to rinse the test
stand and eliminate air bubbles. Vent the system appropriately.
9.3.5.2 Before the next filter is placed for testing (between runs of similar filters) rinse the test skid using full test
flow for a minimum 30 min. Use the NRM to validate a low baseline level of contamination.
9.3.5.3 Flow through flow meters 2 and 3 (In Figures 1-4) should be started at a rate as high as possible (as
recommended by the metrology manufacturers). Flow rate through the main process flow meter (Flow Meter 1 in
Figures 1-4) should also be as high as possible.
9.3.5.4 Ten minutes after starting the flow at a high flow rate, adjust flow meters 2 and 3 to reduce the flow to the
analytical instruments in accordance with the filter supplier recommendations. Operating pressure at P2 should be
30 ± 5 psig (207 ± 34 kPa), unless something different is specified by the metrology manufacturers.
9.4 Ensure that the total flow rate through the flow meters is equal to the flow rate used to test the filter. Start the
OPC, NRM, TOC (if available), and PSDA to determine the background particle, NVR, and TOC concentration. Set
the counting interval of the OPC at 15 minutes. The maximum recommended system background level is 0.05
particle/ml (>0.1 m).
NOTE 2: It is not unusual for new test skids to require one or more days to achieve the system background level required. If,
after 24 hours, the test skid does not appear to be able to meet background requirements, it may be necessary to perform trouble
shooting procedures.
9.5 Particle Sizing Calibration (refer to Appendix 4 for reference)
9.5.1 Calibrate the PSDA used for the test with a NIST traceable standard such as Reference Material 8011, Gold
Nanoparticles, Nominal 10 nm Diameter or similar.
9.5.2 Adjust the flow rates in the test skid and at the metering pump to the settings necessary to achieve an
appropriate concentration of particles for the PSDA. The gold particles’ concentration for this calibration testing
should be high enough for the PSDA to characterize the particle size distribution and should be also sufficiently high
to provide the particle stability (preventing agglomeration). Successful results were achieved with E+13 to E+14 in
concentrate (stock solution), and E+10 to E+11 in the diluted stream.
9.5.3 Start the injection of the traceable standard and collect sizing data for a minimum of 10 minutes.
9.5.4 Determine the number-weighted mean for the reference material.
9.5.5 Determine the difference between the number-weighted mean measured by the PSDA and the Transmission
Electron Microscopy (TEM) particle size reported for the reference material. Use this number as the sizing
correction factor applied to all the silica PSDA measurements.
9.5.6 The calibration process is considered successful if the difference between the mean silica measured by the
PSDA and NIST reference standard mean value is not larger than ± 30% of the NIST specified value.
NOTE 3: The NIST mean particle size for Reference Material 8011 is reported using multiple instruments. Depending on the
instrument used, the mean size may be reported based on number of the particles of the certain size or the volume of the particles
of the certain size. The sizing data provided by NIST does not indicate which weighting is used. In order to compare results from
different tests and/or different facilities, it was decided to use the TEM size reported by NIST as the common comparison.
9.6 Follow the filter supplier’s recommended filter-wetting procedure.
9.7 Integrity Test
9.7.1 Stop all the flow.
9.7.2 Remove the spool piece and drain UPW from the spool piece or housing.
9.7.3 Install the filter.
9.7.4 Provide UPW at the filter supplier’s recommended flow rate to remove air from the filter.
This is a Draft Document of the SEMI International Standards program. No material on this page is to be construed as an official or adopted Standard or Safety Guideline.
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Document Number: 5188A
Date: 2/9/2016
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DRAFT
9.7.5 Release air using the vent port(s), V8, on the filter housing Conduct the filter supplier’s recommended
integrity test.
9.8 Initial Rinse
9.8.1 Filter rinse testing is required for every filter, including multiple identical filters.
9.8.2 Fully open the filter inlet (V-7 in Figure 4) and filter outlet (V-9 in Figure 4).
9.8.3 Adjust the valve downstream from the filter (V-15 in Figure 4) to set the UPW flow through flow meter 1 (in
Figures 1-4) at a rate recommended by the filter manufacturer. Maintain this flow rate for 30 seconds.
NOTE 4: If it takes longer than 10 min to clear air (visual bubbles), investigate possible air leaks on the test skid. If there are no
air leaks on the test skid, change the test filter.
9.8.4 Start the flow through flow meters 2, 3, 4, and 5 (in Figures 1-4) in addition to the flow meter 1 and ensure
that the total flow meets the filter supplier recommended flow rate. Operating pressure at P2 in Figure 3 should be
30 ± 5 psig (207 ± 34 kPa) in addition to the differential pressure across the filter.
9.8.4.1 Start the OPC, NRM, TOC, and PSDA and continue to flow UPW until reaching a stable background level.
NOTE 5: The rinse volume may be specified by the filter supplier. Run the test until reaching a stable background level of the
OPCs and other on-line metrology instruments. The maximum recommended system background level is 0.05 particle/ml (>0.1
m).
9.8.4.2 Determine the background particle contamination.
NOTE 6: Manufacturers may recommend a specific volume of water flow through the filter to achieve cleanliness. However,
more water may be required to achieve a stable, background particle concentration.
9.8.5 Record the data in Table 1.
9.9 Filter Cleanliness Test (if this test is required, the criteria should be defined by the end user)
NOTE 7: A similar test may need to be done for the housing prior to the actual filter test.
9.9.1 When the background is established, isolate the filter unit by closing both inlet (V-7) and outlet (V-9) valves.
9.9.2 Allow filter leaching in situ for at least 12 hrs.
9.9.3 Open the drain valve (V-22 in Figure 4) and drain approximately 50% of the filter water into a measurement
container to flush the valve. In a clean sample container, take a sample of water for analysis. Collect the remaining
portion of the filter water and estimate the total volume. Note that some volume of water will be retained inside the
filter and may need to be added to the estimate. For reference, take also a sample of UPW as a blank.
9.9.4 Send the sample to a qualified lab (to be confirmed by the end user) for filter cleanliness analysis. The
analyses may include TOC, metals, and anions (similar to SEMI F57).
NOTE 8: The level-of-cleanliness criteria should be normalized to the area of the filter and the dilution effect of the volume of
the housing.
9.10 Particle Challenge Test
9.10.1 Silica challenge preparation.
9.10.1.1 Offline dilution of the colloidal silica used for the challenge may be needed in order to achieve the
concentration level required for the test. Dilution should be done using ultrapure water (equal to or better than
specified in §7.6). It is recommended that the colloidal silica not be diluted below 1E12 to ensure long-term
stability.
9.10.1.2 Dissolved residue present in the colloidal silica suspension may result in interference with some PSDAs. If
dissolve residue interference is a concern, the colloidal silica concentrate may be diafiltered using a 5,000 – 10,000
NMWC ultrafiltration filter.
9.10.1.3 Measure the particle size distribution of the of silica challenge using the PSDA and calculate the number
and volume weighted mean particle size. Compare the means size data provided by the silica manufacturer and the
PSDA using the same size weightings. Proceed with the testing if the mean size data are within 30%. If the
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differences are greater than 30%, do not start the test and investigate the reason for differences. Use of another
batch of silica may be required.
9.10.2 Test Procedure:
9.10.2.1 Fully open the inlet (V-7) and outlet (V-9) valves.
9.10.2.2 Adjust the valve downstream from the filter (V-15 in Figure 4) to set the UPW flow through flow meter 1
(in Figures 1-4) at a rate recommended by the filter suppliers. Maintain this flow rate for 30 seconds.
9.10.2.3 Start the flow through flow meters 2 and 3 (in Figures 1-4) in addition to flow meter 1 and ensure that the
total flow rate meets the face velocity requirements of 0.8 cm/min for the dead-end filtration cartridge filter. The
cross-flow UF face velocity criterion is 0.6 cm/min. The calculation of the required test flow rate will require the
surface area of the tested filter/s to be provided by the filter manufacturer.
NOTE 9: The face flow velocity is based on commonly applied in the UPW applications.
9.10.2.4 Continue running the flow until reaching the baseline criteria stated in § 9.7.4.1.
9.10.2.5 Start the metering pump (see Figure 4) to feed the colloidal silica suspension into the UPW inlet. The
pump flow rate should be adjusted to allow the target concentration of colloidal silica into the mixed stream. The
suggested colloidal silica particle concentration is 5.0E+09. Depending on the particle-size distribution, this will be
the equivalent of several parts per billion concentrations as total silica.
9.10.2.6 The concentration is defined by metrology capability and expected minimum retention efficiency of the
filter of 50% (see §3.8).
9.10.2.7 For details of the concentration conversion, refer to Appendix 2.
NOTE 10: 5-15 nm silica particles, LudoxTM, SM30 or similar should be used (readily available from multiple sources). Please
refer to Appendix 2 for the calculation of the particle dosage.
NOTE 11: The colloidal silica suspension should be diluted with UPW. To confirm that the correct concentration of colloidal
silica has been fed to the filter, operate the system for at least 15 min and then take a sample (labeled Sample 1 in Fig.4).
9.10.2.8 Take grab samples in both Sample 1 and Sample 2 locations every 15 min during the experiment. Analyze
all, or part, of the samples for total silica, depending on the number and the cost effectiveness.
9.10.2.9 Verify a stable flow rate and record differential pressure across the filter every 30 min.
NOTE 12: Continue the test run until you have the equivalent of a single monolayer of colloidal silica on the filter surface. Note
11: A longer run (resulting in more than a monolayer) may result in an inaccurate measurement.
9.10.2.10 Record the performance data along with the test skid operating conditions in Tables 1 and 2.
9.10.2.11 For calculation of the retention efficiency, refer to Appendix 3.
10 Related Documents
10.1 SEMI Standards
SEMI C1— Guide for the Analysis of Liquid Chemicals
SEMI C10 — Guide for Determination of Method Detection Limits
SEMI F63 — Guide for Ultrapure Water Used in Semiconductor Processing
SEMI F75 (Reapproved 0309) — Guide for Quality Monitoring of Ultrapure Water Used in Semiconductor
Manufacturing
SEMI F104 — Particle Test Method Guide for Evaluation of Components Used in Ultrapure Water and Liquid
Chemical Distribution Systems
This is a Draft Document of the SEMI International Standards program. No material on this page is to be construed as an official or adopted Standard or Safety Guideline.
Permission is granted to reproduce and/or distribute this document, in whole or in part, only within the scope of SEMI International Standards committee (document
development) activity. All other reproduction and/or distribution without the prior written consent of SEMI is prohibited.
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Document Number: 5188A
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DRAFT
10.2 ASTM Standards1
10.3 ASTM D4517 — Standard Test Method for Low-Level Total Silica in High-Purity Water by Flameless
Atomic Absorption Spectroscopy
10.4 ASTM D5544 — Standard Test Method for On-Line Measurement of Residue after Evaporation of HighPurity Water
10.5 ASTM D7126 — Standard Test Method for On-Line Colorimetric Measurement of Silica
10.6 ASTM D859 — Standard Test Method for Silica in Water
10.7 SEMATECH Documents2
10.8 SEMASPEC 92010949B-STD — Provisional Guide for Determining Particle Contribution by UPW
Distribution Systems
10.9 SEMATECH Technology Transfer #94112615A-XFR — Evaluation of Components Used for Delivering
Semiconductor Process Chemicals
10.10 Other Documents
10.11 FSI International, Technical Report Document Number 1095-TRC-0698, “The Effect of Fluid Dynamics on
Particle Shedding from Semiconductor Fluid-Handling Components”3
10.12 International Technology Roadmap for Semiconductors (ITRS)
10.13 NISTIR 6935 — Particle Size Measurements for Spheres with Diameters of 50 nm to 400 nm 4
1
American Society for Testing and Materials, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, USA; Telephone: 610.832.9585,
Fax: 610.832.9555, http://www.astm.org
2
SEMATECH, 257 Fuller Road, Suite 2200, Albany, NY 12203, USA; Telephone: 518.649.1000, http://www.sematech.org
3
FSI International, 322 Lake Hazeltine Dr., Chaska, MN, USA 55318-1096
4
National Institute of Standards and Technology, 100 Bureau Drive, Stop 3460, Gaithersburg, MD 20899-3460, USA; Telephone: 301.975.6478,
http://www.nist.gov
This is a Draft Document of the SEMI International Standards program. No material on this page is to be construed as an official or adopted Standard or Safety Guideline.
Permission is granted to reproduce and/or distribute this document, in whole or in part, only within the scope of SEMI International Standards committee (document
development) activity. All other reproduction and/or distribution without the prior written consent of SEMI is prohibited.
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Document Number: 5188A
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APPENDIX 1
REQUIREMENTS FOR FILTER TEST SKID
NOTICE: The material in this Appendix is an official part of SEMI [designation number] and was approved by full
letter ballot procedures on [A&R approval date].
A1-1 Requirements for the Construction of the Filter Test Skid
A1-1.1 Commercially available fluorinated polymer distribution system components, such as those made from
PFA, PVDF, PTFE (see NOTE 13), and ECTFE (see NOTE 14) are preferred. When manufactured properly in high
purity factories, these emit low particle concentrations.
A1-1.2 Avoid Polyolefins and Polyvinyls, such as PP, PE and PVC, because they have additives that could either
release particles or provide foodstuff for bacterial growth. Additionally, the surface characteristics of these materials
are typically not as good as the fluorinated materials. PP in particular is sensitive to oxidizers if ozone or peroxide is
used to clean up an idle test skid. PVC is typically glued together which would be both a particle and bacteria
propagation risk.
A1-1.3
Avoid using steel, even stainless, in the flow path.
A1-1.4 When possible, avoid using threaded connectors (known particle generators) upstream of the test skid.
A1-1.5 Gaskets and o-rings used should be made of high-purity materials (SEMI F57 compliant). The
recommended material of construction for gaskets is expanded PTFE and PTFE envelops over EPDM or a
compatible material. O-ring selection should consist of low particulating fluorocarbon or perfluoroelastomer
varieties.
A1-1.6 Use machined polymer components with caution as they may have rough surfaces that will release
particles.
A1-1.7
Do not use ball valves and valves without fluorinated diaphragms because they release particles.
A1-1.8
Avoid dead legs and valves connected to tees: use zero static (branch) valves instead.
A1-1.9 Thermoplastics should be joined by welding techniques which minimize the material degradation as well as
prevent contact with sources of metal or particle generating materials.
NOTE 13: PTFE cannot be injection-molded and is therefore limited to less-critical test skid parts, such as machined components
or lined steel conduits that do not allow easy system modification.
NOTE 14: Valves made of ECTFE (such as zero static valves) have limited commercial availability.
NOTE 15: Other fluorinated materials such as FEP, MFA, ETFE, and PCTFE are scarce in terms of complete component
selection (tube/pipe, fittings and valves).
Table A1-1 Specific Conduit Construction Considerations
Components
Advantages
Disadvantages
Comments
Tubing/Fittings (such as PFA)
Easy to modify the system.
Proven conduit for particle
studies.
Limited to 1” size in flared or
insert system, meaning about
12 GPM max.
Larger sizes should be
thermally welded.
Preferred for low UPW
volumes.
Pipe/Fittings (such as PVDF
and ECTFE)
Size range would allow low
GPM to megafab volumes of
UPW.
Complimentary materials to
those used in fabs for UPW
distribution (PVDF in
particular).
Difficult to modify the system
since it is hard (welded)
plumbing.
Should be thermally welded
by a trained technician.
Required if UPW volume is
excessive.
Experience base with PVDF
in the industry is orders of
magnitude greater than
ECTFE UPW systems.
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Table A1-2 Specific Valve Considerations (Refer to Figures 1 – 4)
Valve Types
Usage Area on Schematic
Comments
Valves – Straight
V1, V7, V9
V15 – V21 could be ball valves but
better adjustment control is possible
with diaphragm types
Use diaphragm type valve with PTFE or
PFA membranes and avoid particulating
ball valves.
Valves – Branch
V5, V10 – V13
Use true zero static valves that have the
branch very close to the run. Avoid
tees/valve combinations. If the volume of
UPW is low then small PFA valves,
regardless of the remainder of the system
construction, would be preferred.
Valves – Sampling
V4, V14
Use small volume valves made of
combinations of PFA, PVDF and PTFE.
Some volume displacement valves are
available where the valve stem (when
closed) is flush with the flowing stream of
UPW.
Valves – Specialty
V2 (Check Valve), V3 (Needle), V8
and V22
V2 – Clean check valve choices for larger
sizes may be difficult to find.
V3 – optional, it may not be included, if
peristaltic pump is used, and run
backwards particles are not injected.
V8 and V22 should be defined by the
supplier of the filter housing.
This is a Draft Document of the SEMI International Standards program. No material on this page is to be construed as an official or adopted Standard or Safety Guideline.
Permission is granted to reproduce and/or distribute this document, in whole or in part, only within the scope of SEMI International Standards committee (document
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Document Number: 5188A
Date: 2/9/2016
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DRAFT
APPENDIX 2
TARGET CHALLENGE PARTICLE CONCENTRATION AND TEST
DURATION
NOTICE: The material in this Appendix is an official part of SEMI [designation number] and was approved by full
letter ballot procedures on [A&R approval date].
A2-1 The concentration of the challenge particles is determined based on the following
considerations:
A2-1.1 To reach no more than one mono-layer of colloidal silica by the test conclusion.
NOTE 16: Both concentration and loading will affect filter performance. Therefore, it is important to maintain consistent test
conditions.
A2-1.2 The challenge test should last long enough to provide sufficient data statistics (more than 6 hrs per run).
A2-1.3 The feed concentration should be high enough to allow good sensitivity of the analytical methods. In the
example below, the challenge concentration of total silica is 5.76 ppb, which allows silica detection by ICP-MS by
an order of magnitude above background silica levels. The PSDA is expected to provide even higher detection
sensitivity.
Parameter
Value
Units
Particle diameter
10.0 nm
Particle volume
523.6 nm3
Particle x-section surface area
78.5 nm2
Density
2.20 g/cm3
Concentration
5.00E+09 #/mL
Face velocity
0.8 cm/min
Surface area
13953.8 cm2
Flow rate
11355.0 mL/min
Mass challenge
5.8 ppb as SiO2
3924.02 ug/hour
Area challenge
2675.43 cm2/hr
Coverage rate
2.8E-01 ug/cm2-hr
1.9E-01 Monolayers/hr
Time to 1 monolayer
5.2 Hrs/monolayer
Time to 3 monolayers
15.65 hours
Other Parameters
5.24E-19 cm3
7.8539E-13 cm2
Filter Area
10" cartridge (pleated)
25 cm long
558 cm wide
Area, m2
1.395
Flowrate
0.6804 m3/hr per cartridge
11340 cm3/min
Figure A2-1
Example of the Calculation of the Time Needed to Reach the Monolayer Thickness of the Challenge Particles
A2-1.4 Conversion of particle challenge concentration per milliliter to mass concentration of silica in parts per
billion:
Mass challenge (ppb) = CF × ρp × π
d3p
6
× 10E9
(A2-1)
A2-1.5 Calculation of the test duration based on a calculated particle coverage of one monolayer:
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filter surface area (cm2 )
Test duration (hrs) = area challenge rate (cm2 /hr)
(A2-2)
Area challenge rate (cm2 /hr) = CF × CSp × fr × 60
(A2-3)
NOTE 17: When running the test with a mono-dispersed particle challenge, use the “mode” (peak value of the size distribution)
of the particle distribution as the particle diameter. When particle size distribution data is unavailable, use nominal/average
diameter provided by the colloidal silica supplier.
A2-1.6 Calculation of filter retention:
% Retention = (1 −
Cout
Cin
) ∗ 100
(A2-4)
A2-1.7 Using silica data:
Cout = CTout − CDout − CTB + CDB
(A2-5)
Cin = CTin − CDin − CTB + CDB
(A2-6)
Cout = CP − CB
(A2-7)
Cin = CF − CB
(A2-8)
A2-1.8 Using particle data:
Where CF = cumulative concentration of feed ≥ x nm (#/mL)
ρp = density of the test particle (grams⁄cm3 )
dp = diameter of the test particle (cm)
CSp = particle cross − sectional area =
πd2
p
4
fr = total flowrate through the filter (mL⁄min)
CT = Total silica (ppb), (including background), measured by ICP-MS
CD = Dissolved silica (ppb), total (including background), measured by colorimetric method
CTB = Total silica background (ppb) , measured by ICP-MS or equivalent
CDB = dissolved silica bckground (ppb) , measured by colorimetric method
CP = cumulative concentration of product ≥ x nm (#/mL)
CB = cumulative concentration of background ≥ x nm (#/mL)
x1 = 10nm and X2 = particle diameter "mode"
NOTE 18: Combination of two values of particle retention based on X1 and X2 diameters provides the reference capability of
particle retention by a filter, taking into account particles size distribution of the colloidal silica particles used for the test.
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APPENDIX 3
CASE STUDY – USE OF PROPOSED SEMI GUIDELINE FOR
MEASURING SUB-20 nm FILTER PERFORMANCE
NOTICE: The material in this Appendix is an official part of SEMI [designation number] and was approved by full
letter ballot procedures on [A&R approval date].
A3-1 Background
A3-1.1 This SEMI document, Guide to Evaluate the Efficacy of Sub-15 nm Filters Used in Ultrapure Water (UPW)
Distribution Systems utilizing colloidal silica as the challenge material to assess filter performance was investigated
in a case study. To evaluate the feasibility of the proposed guide, test runs were performed at Pall Corporation in
Port Washington, NY on October 24 – 28, 2011.
A3-2 Experiment and Results
A3-2.1 The test followed the proposed guidelines, using commercially available Sigma Aldrich Ludox SM30 and
Sigma Aldrich Ludox HS40 colloidal silicas, three commercially available filters, and a soon to be commercially
available TSI LiquiScan NP (LSNP) instrument as the detection method. In addition, ICP-MS was utilized as a
comparison metrology method to the LSNP for concentration measurement of total silica. LSNP is an example of
PSDA described in this document.
A3-2.2 The LSNP comprises of an Atomizer, a Differential Mobility Analyzer (DMA), and a Condensation Particle
Counter (CPC). The DMA and the CPC are readily available from several sources. The unique feature of the LSNP
is the Atomizer. In order to measure particles as small as 5nm, the Atomizer must not produce large droplets, as a
large droplet can generate a non-volatile residue particle from 5-50 nm, and therefore acts as an interference to
detect colloidal silica particles in the same size range.
Figure A3-1
Droplet Size Distributions from Four Different Atomizers
A3-2.3 The Atomizer D shown in Figure A3-1 has the desired characteristics and is used in the LSNP.
A3-2.4 Prior to the start of testing, two lots of SM30 colloidal silica were compared using the LSNP. The lot with
the sharpest monodisperse particle distribution (lot number MKBG9527) was chosen for the feasibility test (see
Figure A3-2).
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Figure A3-2
Lot-to-Lot Particle Size Distributions for Ludox SM30
A3-2.5 Each filter was installed per the manufacturer’s instructions and flushed with UPW until laser light
scattering optical particle counts and Nonvolatile-Residue Monitor (NRM) levels were at pre-installation baseline
levels.
A3-2.6 The filters were challenged with Ludox SM30, diluted from a starting concentration of 2.2E17/mL and with
a mean particle diameter of 12.6 nm. One filter was also challenged with Ludox HS40, with a mean particle
diameter of 18.5 nm.
A3-2.7 ICP-MS samples were taken upstream and downstream of the filters using appropriate sampling ports.
A3-2.8 Filter number 1 was tested using the following sequence:
1. Rinse overnight
2. Challenge concentration of 3E9/mL (diluted from the starting concentration)
3. Challenged with SM30 followed by HS40
A3-2.9 Filter number 2 was tested using the following sequence:
1. Rinse overnight
2. Challenged with 3 sequential concentrations: 3E8/mL, 3E9/mL, 3E10/mL
3. Challenged with SM30
A3-2.10 Filter number 3 was tested using the following sequence:
1. Rinse for 2 hours
2. Challenge concentration of 3E9/mL (challenge time sufficient to develop 2 mono layers)
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3. Challenged with SM30
A3-2.11 For reference, the HS40 particle size distribution is shown in Figure A3-3:
Figure A3-3
Ludox HS40 Particle Distribution
A3-2.12 The measured performance of filter 1 is shown in Figures A3-4 and A3-5:
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Figure A3-4
Filter 1 Retention Performance with SM30, 3E9/mL Challenge
Figure A3-5
Filter 2 Retention Performance with HS40, 3E9/mL Challenge
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A3-2.13 Filter 2, was tested sequentially with three different concentrations (3E8/mL, 3E9/mL and 3E10/mL). The
results are shown in Figures A3-6, A3-7 and A3-8 respectively.
Figure A3-6
Filter 2 Challenged at 3E8/mL for 6.5 Hours
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Figure A3-7
Filter 2 Challenged at 3E9/mL for 3.5 Hours
Figure A3-8
Filter 2 Challenged at 3E10/mL for 2 Hours
A3-2.14 A concentration of 3E8/ml (Figure A3-5) is close to the noise level of the LSNP. A concentration of
3E10/ml (Figure A3-7) indicates that such a high concentration may not relate to the conditions for which the filter
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is designed. However, a concentration of 3E9/mL does indicate an anticipated result of filter performance. It is
acknowledged that even a concentration of 3E9/mL is significantly higher than expected under normal filter usage in
a UPW system.
A3-2.15 Filter 3 was challenged at one concentration to study loading effects. As seen in Figure A3-9, the loading
did not affect the filter performance since a constant efficiency was measured during the length of the constant
challenge concentration test. Tested at a sufficiently low concentration (in this case 3E9/mL), will yield consistent
performance results.
Figure A3-9
Effect of Loading of Filter 3 at a Constant 3E9/mL Challenge (LSNP operated in scan mode)
A3-2.16 Metrology comparisons were also conducted, as shown in Table A3-1, using LSNP, NRM, and ICP-MS.
The Log Reduction Value (LRV) is used to compare the performance of the different metrologies (for example a
90% particle removal efficiency will equate to an LRV value of 1).
Table A3-1 Comparison of Metrology Methods
LRV Measured
Test #2
Method
Test #1
Test #3
Early Loading
Later Loading
LSNP
0.64
1.38
0.48
0.67
NRM
0.63
0.72
0.33
0.53
ICP/MS
0.95
1.02
0.28
0.36
A3-2.17 Agreement amongst the three methods was lower than desired. In most cases, the LSNP indicated the
highest LRVs; the lower LRVs for ICP/MS and NVR are believed to be the result of dissolved residue/silica
interference. The precisions of the LSNP and NVR measurements were similar and better than ICP-MS.
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A3-2.18 The test conditions during the test are shown in Table A3-2. Test results are shown in Table A3-3.
Table A3-2 Test Conditions Report
Parameter/ Conditions
Data
Cleanliness of the skid materials (per F57 or other) – in
compliance (Yes/No)
Yes, TOC < 1 ppb, resistivity > 18.2 mohm.cm, NRM
< 75 ppt
Challenge particles (source, spec)
Colloidal silica, obtained from Sigma Aldrich, Ludox
SM30
Volume of the filter housing/dummy module (between
isolation valves) Note: Useful for extraction test and dilution
rates.
Not measured, estimated to be approximately 0.5 L
O-ring/gasket type
Fluoroelastomer
Housing material of construction
PFA
Filter part number & serial number
Flux per unit area
Surface area
Type of the tested filter (cross flow/dead end, etc.)
Filter material of construction (membrane, support, core, cage,
caps, etc.)
Filter part number and serial number not disclosed
Provide URL to the filter data sheet prepared by the
manufacturer
Not disclosed
Dead end filter capsule
Materials of construction not disclosed
Table A3-3 Test Results
Integrity Test Conditions and Results
Test pressure, allowable diffusive flow, success criteria – pressure decay
Parameters
Test Duration (template – add more columns as needed – the timelines may vary for the
different steps in the test procedure)
0.5 hr
1 hr
1.5 hr
2 hrs
2.5 hrs
Background Test
Feed Flow Rate 1
(L/min)
2.2
2.2
2.2
2.2
2.2
Feed Temperature, C
20
20
20
20
20
Feed Dissolved Oxygen,
ppb (if DO controlled)
NC
NC
NC
NC
NC
.04 total (note:
only ICP-MS
was performed
with the
assumption that
all silica was
colloidal)
0.04 total
0.04 total
0.04 total
0.04 total
Feed NVR, ppb
0.075
0.075
0.075
0.075
0.075
Feed Resistivity, Momcm
18.2
18.2
18.2
18.2
18.2
Feed particles level, #/L,
at >0.05 µ(if OPC
available)
NA
NA
NA
NA
NA
2
2
2
2
2
Feed dissolved and total
Silica, ppb concentration
Feed Pressure (bar)
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Integrity Test Conditions and Results
Test pressure, allowable diffusive flow, success criteria – pressure decay
Parameters
Test Duration (template – add more columns as needed – the timelines may vary for the
different steps in the test procedure)
Product pressure (bar)
0.5 hr
1 hr
1.5 hr
2 hrs
2.5 hrs
1
1
1
1
1
Initial Rinse
Feed Pressure (bar)
2
2
2
2
2
Product pressure (bar)
1
1
1
1
1
Flow Rate (L/min)
2.2
2.2
2.2
2.2
2.2
Product dissolved and
total Silica, ppb
concentration
.04 total
.04 total
.04 total
.04 total
.04 total
Particle count LSNP#1
Below DL
Below DL
Below DL
Below DL
Below DL
Product Particles by
LSNP (both
concentration and size
distribution)
See Figures 1
&2
See Figures 1
&2
See Figures 1
&2
See Figures 1
&2
See Figures 1
&2
Product NVR, ppb
Not measured
Not measured
Not measured
Not measured
Product particles level,
#/L, at >0.1u
Not measured
Not measured
Not measured
Not measured
< 100/L
Particle Challenge Test
Feed Particles by LSNP
(both concentration and
size distribution)
Product Particles by
LSNP (both
concentration and size
distribution)
Feed dissolved and total
Silica, ppb concentration
3E9/mL (size
distribution in
Fig 1)
3E9/mL
3E9/mL
3E9/mL
3E9/mL
See Figures
3&4
See Figures
3&4
See Figures
3&4
See Figures
3&4
See Figures
3&4
.04 total prior to
challenge
_____
______
______
1.7 total
______
_______
_______
_______
0.15 total
Product dissolved and
total Silica, ppb
concentration
#1 The Detection Limit for the LSNP is approximately 1E6/mL
A3-3 Conclusion/Summary
A3-3.1 This case study has shown that the new guide for filter evaluation can be used to measure an LRV < 1, and
as such the filter under test in the case study will provide adequate protection for UPW used to manufacture
semiconductors at 28 nm and larger line width. The challenge particle size used in the case study (12.5 nm) is
smaller than the critical particle size referenced in the most recent edition of the ITRS Roadmap.
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APPENDIX 4
CALIBRATION/VERIFICATION OF THE PSDA
NOTICE: The material in this Appendix is an official part of SEMI [designation number] and was approved by full
letter ballot procedures on [A&R approval date].
A4-1.1 TSI LiquiScanNP (LSNP) was used in this test. For demonstration purposes, non-NIST 10 nm gold particles
were purchased directly from BBI. For this study, the particle diameter as determined by TEM was 8.4 nm. The
nebulizer/DMA reported a number weighted mean of 9.3 nm. The delta satisfies the requirement of this guide
(<30% of the mean particle size).
A4-1.2 The PSDA used required removal of the background non-volatile residue using diafiltration (the procedure
is available from the vendor). Figure A4-1 indicates the effect of the diafiltration to the particle size distribution.
Diafiltration of 10nm Gold particles
Diafiltered 10nm (9.3nm) Gold particles
1.5e+14
Initial diafiltration (4X)
Fresh 1000:1
Fresh 20,000:1
Second diafiltration (4X)
6e+14
Differential number concentration
d (#/mL) / d log (DP)
Differential number concentration
d (#/mL) / d log (DP)
8e+14
4e+14
2e+14
0
1.3e+14
1.0e+14
7.5e+13
5.0e+13
2.5e+13
0.0
4
5
6
7
8
9
10
20
4
5
6
Particle diameter (nm)
7
8
9
10
20
Particle diameter (nm)
Figure A4-1
Effect of Diafiltration for the Particle Size Distribution
A4-1.3 For the purpose of the silica particles analyses, it is suggested to calculate the delta between the mean values
of TEM and PSDA and further adjust the silica particles mean value to the resulting factor.
Fmean = 9.3 – 8.4 = 0.9 → Silica Mean = X – 0.9 nm
(A4-1)
A4-1.4 For testing as prescribed by this guide, NIST particles traceable particles are required. The typical particles
size information provided by NIST is presented in Table A4-1.
Table A4-1 NIST Reference Material 8011 Gold Nanoparticles (source BBI), Nominal 10 nm Diameter
Technique
Analyte Form
Mean Particle
Size (nm)
Expanded
Uncertainty
Atomic Force Microscopy
dry, deposited on
substrate
8.5
±
0.3
Scanning Electron microscopy
dry, deposited on
substrate
9.9
±
0.1
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Technique
Analyte Form
Mean Particle
Size (nm)
Expanded
Uncertainty
Transmission Electron Microscopy
dry, deposited on
substrate
8.9
±
0.1
Differential Mobility Analysis
dry, aerosol
11.3
±
0.1
Dynamic Light Scattering
liquid suspension
13.5
±
0.1
Small-Angle X-Ray Scattering
liquid suspension
9.1
±
1.8
NOTE 19: For the purpose of performance comparison Transmission Electron Microscopy (TEM) has been chosen as reference.
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APPENDIX 5
STATEMENT OF NEED AND OBSERVATIONS FROM INITIAL
INVESTIGATIONS
NOTICE: The material in this Appendix is an official part of SEMI [designation number] and was approved by full
letter ballot procedures on [A&R approval date].
A5-1 Statement of Need
A5-1.1 Optical Particle Counters (OPCs) used in high volume semiconductor manufacturing have reached a
practical measurement limit of 40 nm, with a counting efficiency of only a few percent at this size. However, even at
40 nm, the size detection is above the half pitch of current technology semiconductor devices, rendering the
metrology unable to confirm the presence of potentially “killer particles” at the required sizes. At the same time, the
size of the particles to be controlled in UPW is approaching the capability of the filtration used. Lack of metrology
capability and marginal filtration efficiency substantially increase the risk to the next generation of the wafer
manufacturing technology. UPW ITRS has suggested a risk mitigation strategy based on off-line validation of the
filter performance. Until the particle metrology gap is solved, this approach minimizes the risk to the wafer and
allows conformance with the current ITRS requirements.
A5-1.2 Current methods of filter performance characterization using 50-200 nm PSL (polystyrene latex) spheres
and OPCs, and extrapolating performance to 5-15 nm is inadequate for guaranteeing filter performance at the
extrapolated size. The fact that the filters’ performance is marginal in this range makes it impossible to reliably
extrapolate results. A new method of quantifying filter performance is required for filters with a pore size of 5-15
nm
A5-1.3 It is important to emphasize that the methodology documented in the proposed standard has numerous
limitations, described below. However, the task force believes that it is adequate to the goal this document is called
to address: risk mitigation of the particle control. The purpose of this document is to standardize the filter test
conditions to allow comparison of different filter performances. It is expected that use of this guide will generate
more data that will allow improving the document in future revisions. Not having such a guide or having adequate
particle metrology poses significant risk to the advanced semiconductor manufacturing (based on the information
from ITRS and SEMATECH).
A5-1.4 Reference ITRS documents:
1.
2.
http://www.itrs.net/Links/2011ITRS/2011Chapters/2011Yield.pdf
http://www.itrs.net/Links/2011ITRS/2011Tables/Yield_2011Tables.xlsx
A5-1.5 Reference Sematech Report:
Abbas Rastegar, Arun John Kadaksham, Matt House, Byunghoon Lee, Jae Choi, Masahiro Kishimoto, Aron J.
Cepler, Thomas Laursen, Takeya Shimomura: “EUV Mask and Blank Cleaning Requirements for 16 nm HP node”.
SEMATECH Albany September 2010
A5-1.6 This document addresses metrology limitations as well as with the limitations of the availability of the NIST
traceable challenge particles of the selected type and size range. Because the team developing this document faced
these difficulties commonly used types of the challenge particles were first compared: gold, silica, and PSL.
A5-2 Observations and Investigation for Other Solutions
A5-2.1 The gold particle was the easiest to detect by ICP-MS (Inductively Coupled Plasma Mass Spectrometry) and
had the best particle size distribution. Nevertheless, after much consideration, silica particles were chosen for two
main reasons:
1. It is naturally occurring in UPW. Removal of colloidal silica at the challenge test will be representative to the
real world challenge. Neither gold particles nor PSL occur in UPW.
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2. Out of three types reviewed, silica particles were the worst case scenario at the challenge test (see Figure A51).
NOTE 20: Gold particles require a complicated surface charge modification, using surfactants, in order to represent UPW particle
removal. Even this charge modification may not be representative to the filtration conditions in UPW.
Figure A5-1
Comparative Retention of Different Particle Materials
A5-2.2 However, selecting silica did not come without its consequences since that choice creates a difficulty of
detection. While narrow size distribution can be tested with non-proprietary ICP-MS, silica particles need to be
characterized for their overall particle size distribution first. Particles size distribution can be tested by different
techniques that are commercially available from several companies.
A5-2.3 The guide does not require use of a specific instrument from a particular manufacturer. However, this guide
provides, as a Related Information, a reference and the results of the tests conducted using a particular,
commercially available instrument. A Differential Mobility Analyzer (DMA) (http://www.tsi.com/particle-sizers/)
was tested and found helpful in preliminary tests conducted by the task force. The guide does not require use of this
instrument, but only provides a reference and the results of the tests conducted using this instrument.
A5-2.4 To avoid a need of dealing with proprietary techniques, the Guide does not suggest any specific method or
instrument and leaves this up to end user to choose the one. When such instrument is unavailable, the test can be
conducted without measurement of the particle size distribution, whereas the particle retention efficiency would be
estimated using ICP-MS measurement only. It is expected that the test is going to be used for selection of better
performing filters. Hence testing number of filters under the same conditions and using the same challenge particle
solution will provide an adequate result.
A5-2.5 Silica particles tested during the preliminary testing were Ludox® (registered trademark of Grace Davison).
Other sources of colloidal silica are available and can be used (i.e., REMASOL®, available in both 8 and 14 nm
particle size and Snowtex® available in 10-20 nm particle sizes). It should be noted that none of these colloidal
silicas are NIST certified and none of the commercially available silicas are manufactured for the application of
filter testing.There are two additional silica particles that have been certified by the Institute for Reference Materials
and Measurements (European Reference Materials). ERM-FD100 which is a 20 nanometer silica and ERM-FD304
which is a 42 nm silica (DLS). Obviously, the 42 would not be suited for this work. The ERM-FD100 was prepared
from Koestrosol 1530, Chemiewerk Bad Koestritz GmbH, DE). The ERM-FD100 could be an alternative to the
SM30 if the size of interest is 20 nm and greater.
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LETTER (YELLOW) BALLOT
Document Number: 5188A
Date: 2/9/2016
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DRAFT
A5-2.6 The task force also found significant effects caused by the challenge particle loading and concentration.
Figure A5-2 and A5-3 demonstrate these effects.
Figure A5-2
Effect of Challenge Particles Concentration to the Filter Retention Efficiency
Figure A5-3
Effect of the Filter Loading to the Filter Retention Efficiency
A5-2.7 There is not enough data currently to characterize the effects and their causes. However, the task force
believes that when the number of the particles at the filter surface is increased it establishes a driving force of small
particle through the marginal size pores, overcoming electrochemical interaction between the filter surface and the
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LETTER (YELLOW) BALLOT
Document Number: 5188A
Date: 2/9/2016
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particles. Otherwise stated, particle challenge numbers and filter performance % retention appear to be indirectly
related for some yet unexplained reason.
A5-2.8 Given the fact that increasing the concentration of the particles plays a significant role in impacting filter
performance the document does not provide the minimum retention efficiency of the filter. It would be impossible to
determine the efficiency based on the conditions of the tests limited by current metrology. Hence the method
provides a gross reality check for the ability of the filter to remove particles at the target range. The task force
believes that the ability to remove 50% of the challenge particles (according to the efficiency calculation method
provided by the guide) would indicate that the filter is capable of meeting the needs of today’s UPW requirements.
The choice of the filter is left for the end user to decide.
A5-2.9 The preliminary tests also indicated that silica particles from the same source may have different particles
size distribution – see Figure A5-4.
Figure A5-4
Comparison of Particles Size Distribution of Two Batches Tested
A5-2.10 In cases when performance of different filters does not use any method of particle size characterization, it
is important to use the same source and lot number of colloidal silica and the same test conditions for all
performance tests.
A5-2.11 Additionally, when selecting silica particles for the challenge test, their stability has been validated.
Colloidal silica are supplied with stabilizing agents (NaOH) in order to prevent destabilizing the colloidal system. If
the stabilizing agent is diluted too much, particles aggregation may occur. We do not recommend dilution below 10 5
colloidal silica particles per mL.
A5-2.12 Figure A5-5 presents the results of the experimental work conducted over the period of 18 month. The
colloidal silica suspensions are remarkably stable over this time period. The data shows suspensions repeatedly
prepared from a stock suspension of 1017 particles per ml and diluted down to the range of 10 5, did not significantly
change the particle size distribution. This means that the challenge solution prepared based on this guide conditions
will provide stable performance of the silica particles.
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LETTER (YELLOW) BALLOT
Document Number: 5188A
Date: 2/9/2016
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Phone: 408.943.6900, Fax: 408.943.7943
DRAFT
LETTER (YELLOW) BALLOT
Document Number: 5188A
Date: 2/9/2016
Figure A5-5
Particle Distribution Stability Analyses
A5-3 Conclusion
A5-3.1 In summary, particle mitigation is an important parameter for the production of high yielding wafers. The
industry currently has no means of testing filter goodness to retain particles within UPW streams, making this
document both an important and urgent need for end-users worldwide. The task force recognizes that it is a first
attempt effort and plans to make numerous improvement revisions as more knowledge is gained thorough end-user
usage and feedback.
A5-3.2 In spite of all the limitations mentioned above, this guide provides the first and only method for evaluating
filter performance at sub-15 nm particle sizes, using a realistic challenge material. As the guide is used we anticipate
real-world feedback that will enable the guide to be significantly improved and one day become a standard for
semiconductor filter evaluation.
NOTICE: Semiconductor Equipment and Materials International (SEMI) makes no warranties or representations as
to the suitability of the Standards and Safety Guidelines set forth herein for any particular application. The
determination of the suitability of the Standard or Safety Guideline is solely the responsibility of the user. Users are
cautioned to refer to manufacturer’s instructions, product labels, product data sheets, and other relevant literature,
respecting any materials or equipment mentioned herein. Standards and Safety Guidelines are subject to change
without notice.
By publication of this Standard or Safety Guideline, SEMI takes no position respecting the validity of any patent
rights or copyrights asserted in connection with any items mentioned in this Standard or Safety Guideline. Users of
this Standard or Safety Guideline are expressly advised that determination of any such patent rights or copyrights,
and the risk of infringement of such rights are entirely their own responsibility.
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