Background Statement for SEMI Draft Document 5795
NEW STANDARD: TEST METHOD FOR CONTACTLESS RESISTIVITY
MEASUREMENT OF SEMI-INSULATING SEMICONDUCTORS
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
A number of compound semiconductors, presently including GaAs, InP, SiC, CdTe, Cd(Zn)Te, GaN and AlN, can
be grown as single crystals with high electric resistivity. Semi-insulating wafers fabricated from these ingot
materials are essential for a satisfactory performance of a range of microelectronic devices operating at high
frequency and/or high output power. A standardized test method for routine assessment of the substrate resistivity,
meeting the requirements of the industrial production environment, is necessary. It should be rapid, highly
reproducible and preferentially non-contacting. Topographic evaluation of resistivity variations to verify
specifications across entire wafer areas is desirable.
The metrologic issue to evaluate resistivity without cutting a test sample and generating galvanic contacts has
previously (1998) been addressed by DIN Norm 50448. This now technically outdated document was formally
withdrawn by DIN in 2008. The present document has independently been developed and written by the SEMI TF,
taking into account the current technical status and SEMI style requirements.
Review and Adjudication Information
Task Force Review
Group:
Date:
Contactless Resistivity and Mobility Mapping EU Compound Semiconductor Materials TC
Chapter
October 7, 2015
October 7, 2015
Time & Timezone: 11:00 am CET
MESSE Dresden
Location:
City,
State/Country:
Leader(s):
Standards Staff:
Committee Adjudication
12:00 pm CET
MESSE Dresden
MESSE DRESDEN GmbH
Messering 6
D-01067 Dresden, Germany
Wolfgang Jantz
(wolfgang.jantz@semimap.de)
MESSE DRESDEN GmbH
Messering 6
D-01067 Dresden, Germany
Arnd Weber (arnd.weber@sicrystal.de )
Andrea Busch: +33 (0)4.56.59.30.59
abusch@semi.org
Andrea Busch: +33 (0)4.56.59.30.59
abusch@semi.org
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DRAFT
SEMI Draft Document 5795
NEW STANDARD: TEST METHOD FOR CONTACTLESS RESISTIVITY
MEASUREMENT OF SEMI-INSULATING SEMICONDUCTORS
1 Purpose
1.1 The purpose of this document is to specify methods for the contactless measurement of the resistivity of semi-
insulating samples and wafers.
2 Scope
2.1 This standard test method covers the determination of the electrical resistivity of semi-insulating
semiconductors, including GaAs, InP, CdTe, Cd(Zn)Te, SiC, GaN, and AlN, within the resistivity range 1E5 to
1E12 Ohmcm. It may also be used to characterize other resistivity materials exhibiting resistivity in this range,
including in particular high resistivity silicon.
2.2 The procedures described in this standard measure the time constant  of a network consisting of the resistive
sample and the series capacitance of the sample and the capacitive sensor. Alternatively, a plate sensor (PS ¶ 6.2) or
ring sensor (RS ¶ 6.3) may be used. The evaluation is based on the observation of the time-dependent charge
transfer after application of a voltage step (time domain (TD) evaluation described in Appendix 1) or on measuring
the frequency response of the network (frequency domain (FD) evaluation described in Appendix 2).
2.3 Commercially available measurement system configurations offer the PS combined with TD evaluation and the
RS combined with FD and TD evaluation. Topographic evaluation of the sample area is available as well as
temperature dependent resistivity measurement to evaluate the activation energy ∆E, needed to normalize measured
data to a reference temperature (§ 9).
2.4 The document follows the roadmap laid out by SEMI M54 (GaAs) and SEMI M55 (SiC), identifying resistivity
as an essential material parameter.
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 Referenced Standards and Documents
3.1 SEMI Standards and Safety Guidelines
SEMI M54 – Guide for Semi-Insulating (SI) GaAs Material Parameters
SEMI M55 – Specification for Polished Monocrystalline Silicon Carbide Wafers
NOTICE: Unless otherwise indicated, all documents cited shall be the latest published versions.
4 Terminology
4.1 Definitions of symbols and equations
4.1.1 ρ [Ω•cm] – Resistivity of the resistive material under test.
4.1.2 Rs [Ω] – Resistance of a defined, but not mechanically separated portion of the sample under test.
4.1.3 R [Ω] = ρ L / A – Resistance of a specimen of resistive material, where L [cm] is the length along the current
direction and A [cm2] the cross section perpendicular to the current direction..
4.1.4 Ca, Cs [pF] – Capacitances of the air gap and of the evaluated portion of sample below the top electrode of the
sensor Figure 1A and above the bottom electrode of the sensor Figure 1B, respectively.
4.1.5 ω0 = (RsCs) -1 [s-1] – Characteristic frequency.
4.1.6 s = (ω0)-1 [s] – Relaxation time constant.
4.1.7  = RC [s] – Time constant, where C is the total capacitance of the analyzed network.
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4.2 U [V] – Voltage of the step applied to the sensor.
4.3 ν and ω = 2π ν [s-1] – Frequency and circular frequency of the voltage applied to the sensor.
4.4 ε0 [Cb/V*cm] – Dielectric constant of vacuum.
4.5 ε – Relative dielectric constant of the sample material.
4.6 Q(t) [Cb] – Time-dependent charge on the sensor capacitances Ca, Cs [pF] after application of the voltage step
U [V].
4.7 ds [cm] – Sample thickness.
4.8 Ts [K] – Sample temperature.
4.9 Tn = 298 K (25 0C) – Temperature used for normalization of resistivity data.
4.10 D [cm] – Sensor diameter.
4.11 ∆E [eV] – Activation energy at T = 0 K.
5 Physical background
5.1 Conventionally the resistivity ρ is obtained using Ohms law:
V=IR
(1)
The voltage V is applied to an electrically contacted specimen with known dimensions length L and cross section A
and the resulting current I along L is measured to yield:
ρ = (VA) / (IL)
(2)
5.2 The noncontacting capacitive methods used in this standard are based on the property that a network composed
of a resistance Rs and a capacitance Cs exhibits a relaxation time constant:
s = RsCs
(3)
ω0 = 2π ν0 = (RsCs) -1
(4)
or, equivalently, a characteristic circular frequency:
5.3 Specifically, as described below, the relaxation time constant or characteristic frequency of a network composed
of a resistance and two capacitances connected in series is measured.
5.4 Commercial systems for contactless evaluation of resistivity are either based on the evaluation of a time
constant (Method TD, see Appendix 1) or a characteristic frequency (Method FD, see Appendix 2).
6 Sensors
6.1 The network to be analyzed is physically realized by the sample and sensor arrangement. Depending on
practical considerations either a sensor containing a plate capacitor (Figure 1) or a ring capacitor (Figure 2) is used.
guard ring
top electrode
da
sample
Ca
(Cs, Rs) ds
D
back electrode
Figure 1
Sensor Containing a Plate Capacitor
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sample
da
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ds
de
bottom
electrode
counter
electrode
D
Figure 2
Sensor Containing a Ring Capacitor
6.2 The plate sensor (PS) comprises a top electrode with typically D = 0.1 cm diameter and an extended back
electrode used to place the sample between these electrodes. An annular guard ring around the top electrode ensures
that the electrical field generated by applying a voltage between the electrodes is vertical. The sensor is positioned
such that a small air gap da (typically 50 µm) is obtained between the top electrode and the top surface of the sample.
The cylindrical portion of the sample with diameter D underneath the top electrode is analyzed exclusively, because
only the charge Q(t) below the top electrode is measured (see Appendix 1 for details).
6.3 The ring sensor (RS) consists of a circular bottom electrode, typically with a diameter
D = 0.6 -1 cm, surrounded by a holed counter-electrode, which is formed as an extended plate to deposit the sample.
The bottom electrode, centered in the hole of the counter-electrode, defines an annular gap of width d e. It is recessed
with respect to the counter-electrode such that an air gap da between the bottom electrode and the bottom sample
surface is generated. The circular portion of the sample subject to the electric field above the bottom electrode, with
a diameter of about 1.5 D, is analyzed (see Appendix 2 for details).
6.4 The network generated by the arrangements described in ¶ 6.2 and ¶ 6.3, Figures 1 and 2, is shown in Figure 3.
Here Rs is the resistance of the sample portion wherein the electric field stimulates the current discharging the
dielectric sample capacitance Cs . Ca is the capacitance associated with the air gap. The network analysis by methods
TD (Figure 3A) and FD (Figure 3B) is illustrated. A voltage step generator (SG), charge amplifier (CA), floating
signal generator (FSG) and signal conditioning circuit (SCC) are required. For details, see Appendix 1 and 2.
A
B
CA
CA
FSG
SCC
SG
SG
Figure 3
Equivalent Circuit (network) of the PS and RS Sensors, Analyzed by Methods TD (A) and FD (B)
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7 Sample properties
7.1 The sample requirements are different for the two sensors.
7.2 For analysis with the PS (Figure 1, 2 and ¶ 6.2) the sample must be a slab with a thickness d s between 0.02 and
0.5 cm (200-5000 µm). The sample thickness variation must not exceed 2% across the measurement area D. For
automated topographic evaluation of the entire sample area the overall thickness variation must not exceed 100 µm.
7.2.1 The sample must be large enough to cover a circle with diameter 2D. Its maximum lateral size is limited by
the dimensions of the tool, usually designed to accommodate wafers up to a specified maximum diameter.
7.2.2 The surface of the sample can be as-sawn, but preferably should be lapped or polished. Due to the vertical
orientation of the electric field and the resulting vertical direction of the discharging current, spurious surface
conductivity resulting from surface contamination is uncritical.
7.3 For use with the RS (Figure 2 and ¶ 6.3), the sample may have arbitrary shape but must have one flat surface
covering a circle with diameter 2D, to be placed on top of the RS. Surface contamination resulting in surface
conductance may be critical.
8 Anisotropy of resistivity
8.1 Because the current in the sample is flowing in the directions of the electric field distribution generated by the
sensors PS or RS (Figures 1 and 2), the resistivity is measured along these directions. This constraint is
inconsequential for crystals with isotropic resistivity such as GaAs or InP. However, hexagonal crystals such as SiC
exhibit significant resistivity anisotropy, whence resistivity in this case is described by a second order tensor.
8.2 The electric field direction of the PS (Figure 1) is vertical (perpendicular to the sample surface), whereas the RS
(Figure 1B) generates a field with components both parallel and perpendicular to the sample surface. The measured
resistivity values, therefore, differ according to the resistivity anisotropy of the material.
NOTE 1: For instance, in 6H SiC ρ [║ c] / ρ [┴ c] ≈ 4.8; in 4H SiC ρ [║ c] / ρ [┴ c] ≈ 0.8.
9 Recommended measurement procedures
9.1 Commercial tools using TD evaluation are presently available with PS and RS. The system using the PS is
designed to generate full wafer resistivity topograms. FD evaluation is offered in combination with RS. Taking into
account the respective resistivity measurement ranges (see Appendix 1 and 2) and eventual resistivity anisotropy
(see § 8), FD evaluation is recommended for isotropic material with resistivity up to 1E9 Ω•cm (typically GaAs, InP
and CdTe), whereas TD evaluation is generally applicable, including in particular high resistivity SiC. For
anisotropic material the PS and platelets with their normal parallel to the c-axis are required to obtain ρ [║ c]
9.2 Detailed instructions how to initiate, execute and evaluate the computer-controlled measurement is provided by
the commercial tools, such that operator action is confined to manually placing and removing the sample, inserting
sample identification and measurement definition data, and to starting the automated measurement procedure. As
mentioned, no sample preparation other than careful cleaning of the sample surface (in particular dust removal) is
required.
10 Temperature measurement and resistivity normalization
10.1 The resistivity of semi-insulating semiconductors depends on temperature according to:
ρ (T) ~ exp (∆E/kT)
(5)
Here ∆E is the activation energy at T = 0K needed to transfer electrons/holes occupying the partly ionized
compensation level to the conduction/valence band. For comparison of measurements at different temperatures,
normalization of the measured ρ(Ts) to a reference temperature T n.= 298 K (25°C) is required.
10.2 For semi-insulating semiconductors the temperature dependence ρ (T) is usually very strong (e.g. decreasing
the temperature of GaAs by 7°C increases ρ by 100%). The normalization of data taken at different temperatures
critically depends on ∆E and on the accuracy of the temperature assessment. Therefore, the difference between the
temperature of the sample support plate, measured by a built-in sensor, and the sample temperature Ts measured by a
sensor touching the top surface of the sample, must be taken into account. The sample temperature T s must be
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chosen within the interval (20-30) °C such that the absolute value of the difference δT = (T s – Tn) does not exceed
5 K. The normalized resistivity is then given with satisfactory accuracy by:
ρ (Tn) = ρ (298 K) = ρ (T s) exp (δT ∆E / 7.65)
(6)
NOTE 2: The activation energy ∆E is determined by the compensation process taking place during crystal growth and postgrowth annealing. For standard commercial materials such as n-type semi-insulating GaAs this process is well established and
reliably yields ∆E = 0.75 eV. However, for materials under development, obtained from different suppliers or different crystal
growth runs of the same supplier, ∆E may vary substantially, even within a batch of wafers cut from the same crystal. In this case,
it is recommended to measure ∆E individually for the sample to be characterized. This requires the measurement of ρ(T) at
different temperatures. Respective commercial instrumentation allowing measurement up to 400 °C is available. An approximate
estimate is obtained by measuring ρ (T) at two laboratory temperatures T1, T2 close to Tn = 298 K, to obtain:
∆E = 7.65 ln (ρ (T1)/ρ (T2)) / (T2 – T1)
(7)
11 Persistent photoconductivity
11.1 Some semi-insulating semiconductors, including in particular SiC and Cd(Zn)Te, may exhibit persistent
photoconductivity (PPC). This phenomenon is caused by configurational modification of certain defects upon
ionization, thereby generating an energy barrier against recombination. This process drastically increases the
lifetime of photo-generated carriers, strongly decreasing the resistivity of such material (eventually by orders of
magnitude). Resistivity recovers in the dark with time constants ranging from seconds to days.
11.2 PPC must be removed prior to measurement by storage of the sample in the dark for a sufficient length of time
and subsequent measurement without interim exposure to light. For PPC with a long time constant this procedure
may be accelerated by heating the sample to about 200°C, followed by cooling and measuring in the dark.
12 Evaluation
12.1 The resistivity ρ is calculated according to Equation A1-7 (method TD, Appendix 1) and Equation 7 (method
FD, Appendix 2). Relative dielectric constants ε have been determined by various researchers, as found in the
literature. The following values are suggested:
Table 1 Suggested Dielectric Constants
Material
ε
GaAs
12.9
InP
12.5
SiC
10.0
CdTe
11.0
GaN
9.7
AlN
9.0
Si
11.6
13 Reporting results
13.1 Evaluation Report required elements
13.1.1 Sample material, thickness and size, sketch of sample indicating measurement location,
13.1.2 Instrument used, including method (TD or FD) and type of sensor used (PS or RS),
13.1.3 Dielectric constant used for evaluation, with reference if different from value suggested in this standard,
13.1.4 Measurement temperature,
13.1.5 PPC (if observed) and procedure (waiting, heating) applied to avoid falsification,
13.1.6 Resistivity at measurement temperature,
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13.1.7 If activation energy is known or has been measured: activation energy, normalization temperature and
normalized resistivity,
13.1.8 Operator, place, and date.
14 Related Documents
14.1 Küpfmüller,K. Einführung in die theoretische Elektrotechnik (Introduction to theoretical electrical
engineering), 13th edition, Heidelberg, Springer-Verlag 1990 pp.166 ff and pp 174 ff.
14.2 Stibal R., Windscheif, J. and Jantz W., Contactless evaluation of semi-insulating GaAs wafer resistivity using
time-dependent charge measurement. Semicond. Sci. Technol. 1991: 6, 995.
14.3 Mueller S., Stibal R. and Jantz W., Contactless Topographic Analysis of Locally Inhomogeneous Resistivity in
SiC and Cd(Zn)Te. Materials Science Forum Vols. 600-603 pp 557-560.
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APPENDIX 1
MEASUREMENT OF RESISTIVITY USING METHOD TD
NOTICE: The material in this Appendix is an official part of SEMI [doc 5795] and was approved by full letter
ballot procedures on [A&R approval date].
A1-1 Measurement procedure
A1-1.1 A slab of semiconductor material with area A and thickness d has a vertical (perpendicular to A) resistance
Rs =  d/A and a vertical capacitance Cs =  0 A/d. Hence
RsCs =   0
(A1-1)
independent of sample geometries.
A1-1.2 The network shown in Figure A1-1 (for convenience reproduced below) is generated by the sample together
with the plate sensor PS or ring sensor RS as shown in Figure 1 and Figure 2, respectively. These sample/electrode
arrangements generate sample capacitances Cs and air capacitances Ca connected in series, such that the total
capacitance is
C
(A1-2)
Ca Cs
Ca  Cs
CA
SG
Figure A1-1
Reproduction of Figure 3A, Equivalent Circuit (network) of the Capacitive Sensor, Analyzed by Method TD
A1-1.3 We describe the measurement procedure by assuming that both capacitances Cs and Ca in Figure 3A are
discharged. At time t = 0 a voltage step U (typically 10V) is applied by the signal generator SG, charging the
capacitances instantaneously with an initial
charge:
Q(0)  CU
(A1-3)
A1-1.4 For t > 0, the voltage across the charged Cs causes a carrier transport through the sample resistance Rs,
gradually discharging Cs. With decreasing voltage across Cs and a corresponding voltage increase across Ca
additional charge is transported to Ca from the external source SG because the applied voltage U is held constant and
Ca > C. Eventually, Cs is completely discharged and the charge on Ca is:
Q()  C aU .
(A1-4)
A1-1.5 While charge redistribution is in progress, the instantaneous, time dependent charge is described by:
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Ca2
t / 
Q(t ) 
U (1  e
)  Q(0)
Ca  C s
(A1-5)
  Rs (Ca  Cs ).
(A1-6)
where
A1-1.6 This charge transient Q(t), illustrated in Figure A1-2, is converted into a voltage transient with the charge
amplifier CA, to be recorded by a digital voltmeter.
Q
Q0
0

t
Figure A1-2
Time Dependence of the Total Charge of the Network Shown in Figure 3A.
A1-1.7 By inserting the above relations for Q(0), Q() and  into (6) yields:

C s
(C a  C s ) 0

Q(0)
Q() 0
(A1-7)
A1-1.8 It is seen that the desired  is completely determined by the material constant  and the measured quantities
Q(0), Q() and .
A1-2 Measurement range
A1-2.1 The TD measurement range is limited on the low resistivity side by the finite rise time of the voltage step
and the charge amplifier, resulting in an electronically generated transient on the order of about 10 ns which would
falsify a comparably fast charge relaxation transient. Commercial instrumentation allows evaluation of resistivity
down to 1E5 Ω•cm, which corresponds to a relaxation transient time constant of about 100 ns. This limit coincides
with the generally accepted lower limit of resistivity of semi-insulating materials.
A1-2.2 The upper limit of the TD measurement range, i.e. the evaluation of very slow transients on the order of
seconds, is determined by amplifier drift stability. Moreover, for a topographic evaluation requiring thousands of
individual data points the total measurement time may become prohibitive. These pragmatic reasons have led
commercial suppliers to adopt an upper limit of the TD evaluation approach of 1E12 Ω•cm
A1-2.3 In ¶ 7.2, the sample thickness ds has been limited to 5 mm, although a dependence of ρ on ds is not observed
for ds up to 15 mm. Apart from practical considerations (common wafer and test sample dimensions) a thickness
limit has been imposed because the corresponding decrease of Cs eventually impairs the measurement accuracy.
Hence useful data may be generated with samples ds > 5mm, but must not be claimed to be obtained in accordance
with this standard.
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A1-3 Analysis of inhomogeneity
A1-3.1 Upon analyzing extended samples such as wafers fabricated for device processing, gradual  variations of
locally (within the volume probed by one individual measurement) homogeneous material as well as locally
inhomogeneous material, (with material phases of different  intermixed within the volume probed by one
individual measurement) is encountered. The TD measurement technique allows assessment of these properties.
Local homogeneity is indicated by an undistorted mono-exponential transient. Upon stepping to an adjacent
measurement spot on a locally homogeneous material, a transient with perhaps different time constant, but again
mono-exponential behaviour, will be found. Conversely, local inhomogeneity is revealed by a multi-exponential
transient and/or differences between the measured values of Q(0) and Q() and those calculated from the air gap da
and the sample parameters (,ds).
A1-3.2 For small local inhomogeneity, as indicated by a slightly deformed mono-exponential transient, a best
mono-exponential fit to the recorded transient yields an average . This average value does not depend on the spatial
distribution of the different resistivities (e.g. variations in the bulk material or near the sample surfaces). Since such
variations may influence other measurement techniques (e.g. Hall or spreading resistance) in a different way,
discrepancies are likely to be observed in this case.
NOTE 3: For strong local inhomogeneity, caused either by two or more intermixed material phases with substantially different
resistivity or by a wide quasi-continuous distribution of locally intermixed resistivities, the fitting of a mono-exponential transient
yielding one  value will gradually cease to be physically meaningful. Mathematical analysis of multi-exponential transients is
possible to obtain more detailed information on inhomogeneous resistivity compositions. However, such investigations are
beyond the scope of standardized evaluation.
NOTE 4: Quite generally a standardized resistivity evaluation of material with strong local inhomogeneity is not possible. In
particular, conventional contacting resistivity measurements (e.g. 4-point probing) yield just one resistivity value, which, as
mentioned above, is misleading or meaningless if the investigated material is irregularly composed of phases with widely
different resistivities.
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APPENDIX 2
MEASUREMENT OF RESISTIVITY USING METHOD FD
NOTICE: The material in this Appendix is an official part of SEMI [doc 5795] and was approved by full letter
ballot procedures on [A&R approval date].
A2-1 Measurement procedure
A2-1.1 The FD measurement procedure is shown in Figure A2-1, reproduced here for convenience
FSG
SCC
Figure A2-1
Reproduction of Figure 3B, Equivalent Circuit (Network) of the Capacitive Sensor, Analyzed by Method FD
A2-1.2 An AC signal with variable frequency ω supplied by a floating signal generator (FSG) is fed into the
network via Ca, generating an AC current which depends on the stimulating frequency. The signal conditioning
circuit (SCC) converts the resulting voltage into a DC voltage to obtain the frequency response of the network
(Figure A2-2) recorded by a digital voltmeter. This response allows to deduce the cut-off frequency ω0 = (RsCs)-1
(Equation 4) and subsequently to obtain  = ω0 / 0.
A2-1.3 The characteristics of the FSG and the SCC as well as parasitic electronic components and the constant C a
are taken into account by the analysis. The thickness of the material slightly influences the frequency response. This
dependency can be corrected using the measurement voltage height at ω 0, which gives information about the sample
thickness.
Figure A2-2
Frequency Response of a homogeneous GaAs Wafer
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: 5795
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DRAFT
A2-2 Analysis of local inhomogeneity
A2-2.1 The network Figure 3B can be described by a system of complex equations. The solutions yield values for
the components of the electrical network. Deviations of the measured frequency response from a model calculation
assuming homogeneous resistivity allows the identification of local inhomogeneity.
A2-3 Measurement range
A2-3.1 The resistivity range of commercially available systems based on the FD approach is 1E5 to 1E9 Ω•cm,
covering the resistivity range of semi-insulating GaAs. This range requires a spectral range of 100 Hz to 1 MHz,
realizable with standard electronic circuitry.
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. 5795  SEMI
LETTER BALLOT
Document Number: 5795
Date: 2/8/2016
Semiconductor Equipment and Materials International
3081 Zanker Road
San Jose, CA 95134-2127
Phone: 408.943.6900, Fax: 408.943.7943
DRAFT
APPENDIX 3
REFERENCES SAMPLES
NOTICE: The material in this Appendix is an official part of SEMI [doc. 5795] and was approved by full letter
ballot procedures on [A&R approval date].
A3-1 Reference Samples
A3-1.1 Semi-insulating reference samples certified by commercial or government authorized institutions (e.g. NIST
or PTB) at present are not available.
A3-1.2 As a substitute, reference samples, using commercially available n-type semi-insulating substrates are
suggested to verify the accuracy resistivity measurement systems of this standard. Depending on the customer
request, GaAs or other materials may be used. The following conditions must be met:
Table A3-1 Generation of Resistivity Reference Samples
Topic
Condition
Wafer thickness
0.04 cm - 0.1 cm
Minimum sample size
2 cm x 2 cm
Sensor
PS, D = 0.1 cm
Evaluation method
TD
Resistivity data array
10 x 10,with 0.1 cm step
Temperature
(25 +/-3)°C
Dielectric constant
as given in this standard
Standard deviation
≤ 2%
Normalization
to 25°C with ∆E =0.75 eV (GaAs) or as measured
according to section 10 (other materials)
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Standards and Safety Guidelines are subject to change without notice.
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and the risk of infringement of such rights are entirely their own responsibility.
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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LETTER BALLOT
Document Number: 5795
Date: 2/8/2016