ASTM F1390-97

Standard Test Method for Measuring Warp on Silicon Wafers by Automated Noncontact Scanning

SCOPE
1.1 This test method covers a noncontacting, nondestructive procedure to determine the warp of clean, dry semiconductor wafers.
1.2 The test method is applicable to wafers 50 mm or larger in diameter, and 100 [mu]m (0.004 in.) approximately and larger in thickness, independent of thickness variation and surface finish, and of gravitationally-induced wafer distortion.
1.3 This test method is not intended to measure the flatness of either exposed silicon surface. Warp is a measure of the distortion of the median surface of the wafer.
1.4 This test method measures warp of a wafer corrected for all mechanical forces applied during the test. Therefore, the procedure described gives the unconstrained value of warp. This test method includes a means of canceling gravity-induced deflection which could otherwise alter the shape of the wafer.  The resulting parameter is described by Warp(2) in Appendix X2 Shape Decision Tree in SEMI Specification M1. (See Annex A1.)  Note 1-Test Method F657 measures median surface warp using a three-point back-surface reference plane. The back-surface reference results in thickness variation being included in the recorded warp value. The use (in this test method) of a median surface reference plane eliminates this effect. The use (in this test method) of a least-squares fit reference plane reduces the variability introduced in three-point plane calculations by choice of reference point location. The use (in this test method) of special calibration or compensating techniques minimizes the effects of gravity-induced distortion of the wafer. %1.5 The values stated in SI units are to be regarded separately as the standard. The values given in parentheses are for information only.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 09-Jun-1997
• ICS: 29.045 - Semiconducting materials
• Technical Committee: F01 - Electronics

Relations

• Replaced By: ASTM F1390-02 - Standard Test Method for Measuring Warp on Silicon Wafers by Automated Noncontact Scanning (Withdrawn 2003)
• Effective Date: 10-Dec-2002

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact
ASTM International (www.astm.org) for the latest information.
Designation: F 1390 – 97
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Test Method for
Measuring Warp on Silicon Wafers by Automated
1
Noncontact Scanning
This standard is issued under the fixed designation F 1390; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 This test method covers a noncontacting, nondestructive 2.1 ASTM Standards:
procedure to determine the warp of clean, dry semiconductor F 657 Test Method for Measuring Warp and Total Thickness
wafers. Variation on Silicon Slices and Wafers by Noncontact
3
1.2 The test method is applicable to wafers 50 mm or larger Scanning
3
in diameter, and 100 μm (0.004 in.) approximately and larger in F 1241 Terminology of Silicon Technology
thickness, independent of thickness variation and surface 2.2 SEMI Standard:
finish, and of gravitationally-induced wafer distortion. M 1 Specifications for Polished Monocrystalline Silicon
4
1.3 This test method is not intended to measure the flatness Wafers
of either exposed silicon surface. Warp is a measure of the
3. Terminology
distortion of the median surface of the wafer.
1.4 This test method measures warp of a wafer corrected for
3.1 Definitions:
all mechanical forces applied during the test. Therefore, the
3.1.1 mechanical signature— of an instrument, that compo-
procedure described gives the unconstrained value of warp.
nent of a measurement that is introduced by the instrument and
This test method includes a means of canceling gravity-
that is systematic, repeatable, and quantifiable.
induced deflection which could otherwise alter the shape of the
3.1.2 median surface—of a semiconductor wafer, the locus
2
wafer. The resulting parameter is described by Warp(2) in
of points equidistant from the front and back surfaces.
Appendix X2 Shape Decision Tree in SEMI Specification M 1.
3.1.3 quality area—that portion of a wafer within the
(See Annex A1.)
specified parameter is determined.
3.1.4 reference plane— of a semiconductor wafer, a plane
NOTE 1—Test Method F 657 measures median surface warp using a
from which deviations are measured.
three-point back-surface reference plane. The back-surface reference
results in thickness variation being included in the recorded warp value. 3.1.5 reference plane deviation (RPD)—the distance from a
The use (in this test method) of a median surface reference plane
point on a reference plane to the corresponding point on a
eliminates this effect. The use (in this test method) of a least-squares fit
wafer surface. A dome-shaped wafer is considered to have
reference plane reduces the variability introduced in three-point plane
positive RPD at its center; a bowl-shaped wafer is considered
calculations by choice of reference point location. The use (in this test
to have negative RPD at its center.
method) of special calibration or compensating techniques minimizes the
3.1.6 thickness—of a semiconductor wafer, the distance
effects of gravity-induced distortion of the wafer.
through the wafer between corresponding points on the front
1.5 The values stated in SI units are to be regarded sepa-
and back surfaces.
rately as the standard. The values given in parentheses are for
3.1.7 wafer—of a semiconductor, the difference between
information only.
the maximum and minimum distances of the median surface of
1.6 This standard does not purport to address all of the
a free, unclamped wafer from a reference plane.
safety concerns, if any, associated with its use. It is the
3.1.7.1 Discussion—Although warp may be caused by un-
responsibility of the user of this standard to establish appro-
equal stresses on the two exposed surfaces of the wafer, it
priate safety and health practices and determine the applica-
cannot be determined from measurements on a single exposed
bility of regulatory limitations prior to use.
surface. The median surface may contain regions with upward
or downward curvature or both; under some conditions the
median surface may be flat (see figures in Appendix X1).
1
This test method is under the jurisdiction of ASTM Committee F-1 on
3.2 Other definitions relative to silicon material technology
Electronicsand is the direct responsibility of Subcommittee F01.06 on Silicon
can be found in Terminology F 1241.
Materials and Process Control.
Current edition approved June 10, 1997. Published August 1997. Originally
{1
published as F 1390–92. Last previous edition F 1390–92 .
2
Poduje, N., “Eliminating Gravitational Effect in Wafer Shape M
...