Background Statement for SEMI Draft Document 5447A
New Standard: TERMINOLOGY FOR THROUGH GLASS VIA AND
BLIND VIA IN GLASS GEOMETRICAL METROLOGY
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
This document was written by the Inspection and Metrology Task Force of the 3DS-IC Committee to provide the
3DS-IC Community a common set of definitions to describe the physical characteristics of the openings etched in
glass for use as through silicon vias (TGVs), which are not defined in current SEMI Standards. For completeness,
we also include definitions of certain terms that are already defined in current SEMI Standards. It addresses
parameters and definitions for glass as a substrate or wafer for 2.5 and 3DS-IC applications. For each parameter (or
group of parameters), the various technologies that are used will be listed, along with any limitations and/or issues
and needs particular to that technology and to making valid comparisons to the others.
Draft document 5447A differs from 5447 in that the terminology is extended to make it clear that the definitions
apply to all glass form factors and are not limited to glass wafers.
This document was developed in the Inspection and Metrology TF of N.A. 3DS-IC Committee. The original
SNARF for this was approved July 10, 2012. Draft Document 5447 was approved for yellow ballot in Cycle 1 or
Cycle 2 in CY2014, by the N.A. 3DS-IC Committee. Draft Document 5447A was approved for yellow ballot in
Cycle 3 or Cycle 4 in CY2014, by the N.A. 3DS-IC Committee.
Review and Adjudication Information
Task Force Review
Committee Adjudication
Group:
Inspection & Metrology Task Force
NA 3DS-IC (Three-dimensional Stacked
Integrated Circuits) Technical Committee
Date:
Tuesday, July 8, 2014
Tuesday, July 8, 2014
Time & Timezone:
8:00 am to 10:00 am (U.S. Pacific Time)
3:00 pm to 5:00 pm (U.S. Pacific Time)
Location:
San Francisco Marriott Marquis Hotel
780 Mission Street
San Francisco Marriott Marquis Hotel
780 Mission Street
City, State/Country:
San Francisco, California 94103
San Francisco, California 94103
Leader(s):
David Read
Victor Vartanian, SEMATECH
Richard Allen (NIST)
Sesh Ramaswami (Applied Materials)
Urmi Ray (Qualcomm)
Chris Moore (BayTech-Resor)
Paul Trio (SEMI NA)
Paul Trio (SEMI NA)
408.943.7041, ptrio@semi.org
408.943.7041, ptrio@semi.org
This meeting’s details are subject to change, and additional review sessions may be scheduled if necessary. Contact Standards
staff for confirmation.
Standards Staff:
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
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Phone: 408.943.6900, Fax: 408.943.7943
SEMI Draft Document 5447A
New Standard: TERMINOLOGY FOR THROUGH GLASS VIA AND
BLIND VIA IN GLASS GEOMETRICAL METROLOGY
1 Purpose
1.1 The purpose of this document is to provide clear and commonly accepted definitions of through glass vias
(TGV) and to provide a consistent terminology for the understanding and discussion of metrology issues important
them.
2 Scope
2.1 This document attempts to describe measurands and geometrical features of through and blind vias in glass.
2.2 The focus of this document is on geometry-related metrology and measurands important for definition and
control of fabrication and inspection operations on structures that include openings for TGV.
2.3 This document is intended for through glass vias and blind vias in glass.
2.4 This document can be applied to all through and blind vias as they occur in any flat surfaces made of glass, for
instance wafers or sheets.
2.5 This document adopts and adapts structure and wording from SEMI document SEMI 3D1 (Terminology for
Through Silicon Via Metrology).
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 document does not include terminology for vias in silicon or other materials.
3.2 This document does not describe measurement procedures and test methods.
3.3 This document does not discuss statistical considerations.
4 Referenced Standards and Documents
4.1 SEMI Standards and Safety Guidelines
SEMI P35 — Terminology for Microlithography Metrology
SEMI E89 — Guide for Measurement System Analysis (MSA)
SEMI 3D1 — Terminology for Through Silicon Via Geometrical Metrology
4.2 NIST Documents1
NIST Documents NBSIR 79-1758 — The Calibration of a Roundness Standard
4.3 Other Documents
International Technology Roadmap for Semiconductors, 2009 Edition, Chapter on Interconnect
NOTICE: Unless otherwise indicated, all documents cited shall be the latest published versions.
5 Abbreviations and Acronyms
5.1 TGV — Through glass via
5.2 BV — Blind via
1
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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5.3 CD — Critical Dimension
5.4 SR — Surface Roughness
6 Definitions
6.1 Glass substrate — any flat surface made of glass, for instance wafers or sheets.
6.2 Through glass via opening (TGV) — a hole or recess in a glass substrate that begins at the top surface and
extends fully through the substrate from one surface to the other. It may be empty, contain a conductor or contain
additional layers such as an insulator between the conductor and the glass, a diffusion barrier on the glass surface
within the hole, or others. See Figure 1.
Figure 1
TGV with sidewall at top glass surface.
6.3 Blind via opening BV — a hole or recess in a glass substrate that begins at the top surface and does not extend
fully through the substrate from one surface or to the other. It may contain a conductor or additional layers. Figure 2
shows blind via versus through via.
6.4 Top surface — the substrate surface where the TGV opening is initially created and where the excavation of the
TGV begins. This surface is defined to be horizontal; its perpendicular is defined to be vertical. Figure 1 shows a
sketch of a TGV at the top surface.
6.5 Bottom surface — the substrate surface opposite the top surface.
6.6 Edge — the rim or edge of via at the top surface.
6.7 Area — geometrical area of the TGV opening in a particular horizontal plane. In figure 1, the area of the TGV
opening is the area covered by the light upward diagonal line pattern.
6.7.1 Top area — area of the TGV opening at the top surface of the substrate.
6.8 Depth — the distance, measured from the top surface vertically toward the bottom surface, between the top
surface and the deepest point of the TGV opening.
Figure 2
TGV and Blind Via in glass substrates
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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6.8.1 Intermediate depth — the distance measured from the top surface to a selected level less than the full depth of
the TGV opening. For example, the TGV opening area at an intermediate depth of 50 % of the substrate thickness
might be of interest.
6.8.2 Full depth TGV — a TGV opening that extends from the top surface to the bottom surface of the substrate.
6.9 Reported horizontal dimensions — the scheme and numerical values used to specify the breadth of a TGV. The
breadth of a TGV may be specified in a variety of ways depending on circumstances such as the fabrication method
and the measurement tools that are available. This standard adopts the major and minor diameters, as defined below,
as the reference geometrical construction for the horizontal dimensions of the TGV opening. Other possible
examples of reference dimensions, not defined in this standard, include the diameter of a circle in a horizontal plane
that can be inscribed in the TGV opening, the side of a square that can be inscribed in the TGV opening, etc. The
geometrical terms and definitions herein are intended to be consistent, to the extent feasible, with their standard
usage in the literature on geometry, in order to promote the use of existing mathematical methods and software and
to minimize confusion.
6.9.1 Center — the center of a TGV opening in any horizontal plane is the centroid (“center of gravity”) of the area
of the TGV.
6.9.2 Chord — A straight line that extends from one point on the sidewall of the TGV opening in a specific
horizontal plane to another such point in the same plane.
6.9.3 Diameters and center point of major diameter
6.9.3.1 Major diameter — the length of the longest chord of the TGV opening in any particular horizontal plane.
6.9.4 There is no requirement that this diameter pass through any geometrical center or centroid of the TGV
opening.
6.9.5 There is no relationship implied between the length of the major diameter and the area of the TGV opening.
Figure 3 indicates the major and minor diameters of a TGV opening. The unit for this dimension shall be the
micrometer.
6.9.5.1 Center point of the major diameter — the point on the major diameter equidistant from its ends.
6.9.5.2 Minor diameter — the length of the shortest chord that passes through the center point of the major diameter.
Under this definition the minor diameter need not be at 90° to the major diameter, and no relationship is specified or
assumed between the length of the minor diameter and the area of the TGV opening.
Minor diameter
Major diameter
Center point of
Major diameter
Figure 3
Diameters and center point of a via
6.9.5.3 Top major diameter — the major diameter of the TGV opening being characterized, measured at the top
surface of the substrate.
6.9.5.4 Bottom major diameter — the major diameter of the TGV opening being characterized, measured at the
bottom surface of the substrate.
6.9.5.5 90 % depth major diameter — the major diameter of the TGV opening being characterized, measured in the
horizontal plane at 90 % of the depth of the TGV.
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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6.9.5.6 X % depth major diameter — the major diameter of the TGV opening being characterized, measured in the
horizontal plane at x % of the depth of the TGV
6.9.5.7 Top minor diameter — the minor diameter of the TGV opening being characterized, measured at the top
surface of the substrate.
6.9.5.8 Bottom minor diameter — the minor diameter of the TGV opening being characterized, measured at the
bottom surface of the substrate.
6.9.5.9 90 % depth minor diameter — the minor diameter of the TGV opening being characterized, measured in the
horizontal plane at 90 % of the depth of the TGV.
6.9.5.10 X % depth minor diameter — the major diameter of the TGV opening being characterized, measured in the
horizontal plane at x % of the depth of the TGV.
6.10 Critical dimension (CD) — This document defines all the CDs of the TGV opening based on the length of the
minor diameter at various depths within the TGV opening. Whenever a CD is given, the plane in which it is
measured shall be specified. Some examples follow.
6.10.1 Top CD — CD (length of minor diameter) of the TGV opening at the top surface.
6.10.2 CD at 90% depth — CD (length of minor diameter) at an intermediate depth of 90% of the depth of the TGV.
6.10.3 Bottom CD — CD (length of minor diameter) of the TGV opening at the bottom surface. Use of this term
implies that the TGV opening is a full thickness TGV.
6.11 Roundness — Roundness is the difference between maximum and minimum circle.
6.11.1 Top roundness — roundness at the top surface of the substrate.
6.11.2 Bottom roundness — roundness at the bottom surface of the substrate.
6.11.3 Roundness at x % depth — roundness at the intermediate depth of x% of the depth of the TGV.
6.11.4 Maximum circle – the smallest circle that encompasses all of the opening points.
6.11.5 Minimum circle – the largest circle that leaves all points of the opening outside.
Maximum circle
Minimum circle
Figure 4
Roundness of a via
6.12 Sidewall — the wall surrounding the via.
6.13 Sidewall surface texture — the local character of the surface formed by the sidewall of a TGV opening.
6.13.1 Sidewall topography, ST — the quantitative measure of the sidewall surface texture.
6.13.1.1 For scallop-based etch processes, the sidewall topography is given by Equation (1)
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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𝒔𝒄𝒂𝒍𝒍𝒐𝒑 𝒔𝒊𝒛𝒆
𝑻𝒐𝒑 𝒎𝒊𝒏𝒐𝒓 𝒅𝒊𝒂𝒎𝒆𝒕𝒆𝒓
(1)
6.13.1.2 For other etch processes, the sidewall surface topography is determined by use of idealized geometrical
shapes that are drawn within and outside of the representation of the TGV sidewall. The ellipse is expected to be the
most useful such shape for measurements in horizontal planes through the TGV. The circle is a special case of the
ellipse. The rectangle may be chosen for TGV openings that conform better to this shape. The rectangle or the
trapezoid may be the most useful such shape for measurements on vertical planes through the TGV. The sidewall
topography is defined by Equation (2) for rectangles or trapezoids truncated at the top and bottom and Equation (3)
for circles or ellipses, where ST is the sidewall topography, Aouter is the area of the circumscribed ellipse or rectangle,
and Ainner is the area of the inner ellipse or rectangle.
𝑺𝑻 =
𝑺𝑻 =
𝑨 𝒐𝒖𝒕𝒆𝒓−𝑨 𝒊𝒏𝒏𝒆𝒓
𝟐 𝑨 𝒊𝒏𝒏𝒆𝒓
𝑨 𝒐𝒖𝒕𝒆𝒓−𝑨 𝒊𝒏𝒏𝒆𝒓
𝟒 𝑨 𝒊𝒏𝒏𝒆𝒓
(2)
(3)
6.13.2 Surface roughness SR — not defined; see NOTE 1:
Via sidewall roughness is not defined in this document although it is an important characteristic of the TGV and is
hypothetically defined in the same manner as surface roughness, but there is currently no known measurement to characterize
sidewall roughness. Further, the value of sidewall roughness will depend on the SEMI definition used and the technique used to
measure it.
6.13.3 Tilt — angle in degrees between the top surface normal of the substrate and the line connecting the center of
the TGV at the top surface with the deepest point of the TGV.
6.13.4 Note: An angle of 0º indicates an absence of tilt.
6.13.5 Sidewall angle — angle in degrees between a best-fit line to the sidewall of the TGV and the horizontal plane.
Figure 5 shows examples of possible shapes of the sidewall and the sidewall angle.
6.13.5.1 An angle less than 90º indicates a TGV diameter that decreases with increasing depth, while an angle of
more than 90º indicates a TGV with a diameter that increases with depth. The line should accurately track the
direction of the top 90%, or more, of the sidewall of the TGV.
Figure 5
Sidewall angle (angle between best fit line and horizontal)
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6.14 Pitch — distance between the centroid of a TGV and the centroid of an adjacent TGV.
6.14.1 Pitch, average — average spacing between centroids of a specified group of TGV arranged along a line.
6.14.2 Pitch, minimum — minimum spacing between centroids of any two neighboring TGV within a group of
TGV arranged along a line.
6.15 Reveal — Distance remaining between the deepest point within a TGV opening and the bottom surface of the
substrate. This dimension may be calculated as the difference between the substrate thickness and the TGV depth.
6.16 Aspect ratio — ratio of the depth of a TGV opening to its top major diameter.
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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