ASTM F847-94(1999)

Standard Test Methods for Measuring Crystallographic Orientation of Flats on Single Crystal Silicon Wafers by X-Ray Techniques

SCOPE
1.1 These test methods cover the determination of [alpha], the angular deviation between the crystallographic orientation of the direction perpendicular to the plane of a fiducial flat on a circular silicon wafer, and the specified orientation of the flat in the plane of the wafer surface.
1.2 These test methods are applicable for wafers with flat length values in the range of those specified for silicon wafers in SEMI Specification M1. They are suitable for use only on wafers with angular deviations of less than +5°.  
1.3 The orientation accuracy achieved by these test methods depends directly on the accuracy with which the flat surface can be aligned with a reference fence and the accuracy of the orientation of the reference fence with respect to the X-ray beam.  
1.4 Two test methods are covered as follows:  Sections Test Method A---X-Ray Edge Diffraction 8 to 13 Method Test Method B---Laue Back Reflection 14 to 18 X-Ray Method
1.4.1 Test Method A is nondestructive and is similar to Test Method A of Test Methods F26 except that it uses special wafer holding fixtures to orient the wafer uniquely with respect to the X-ray goniometer. The technique is capable of measuring the crystallographic direction of flats to a greater precision than the Laue back reflection method.  
1.4.2 Test Method B is also nondestructive, and is similar to Test Method E82, and to DIN 50 433, Part 3, except that it uses "instant" film and special fixturing to orient the flat with respect to the X-ray beam. Although it is simpler and more rapid, it does not have the precision of Test Method A because it uses less precise and less expensive fixturing and equipment. It produces a permanent film record of the test.  Note 1-The Laue photograph may be interpreted to provide information regarding the crystallographic directions of wafer misorientation; however, this is beyond the scope of the present test method. Users desiring to carry out such interpretation should refer to Test Method E82 and to DIN 50 433, Part 3, or to a standard X-ray textbook.    With different wafer holding fixturing, Test Method B is also applicable to determination of the orientation of a wafer surface.
1.5 The values stated in inch-pound units are to be regarded 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. For specific hazard statements see Section 6.

General Information

• Status: Historical
• Publication Date: 31-Dec-1998
• ICS: 29.045 - Semiconducting materials
• Technical Committee: F01 - Electronics

Relations

• Replaced By: ASTM F847-02 - Standard Test Methods for Measuring Crystallographic Orientation of Flats on Single Crystal Silicon Wafers by X-Ray Techniques (Withdrawn 2003)
• Effective Date: 10-Dec-2002

Standards Content (Sample)

NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: F 847 – 94 (Reapproved 1999)
Standard Test Methods for
Measuring Crystallographic Orientation of Flats on Single
Crystal Silicon Wafers by X-Ray Techniques
This standard is issued under the fixed designation F 847; 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.
,
2 3
and to DIN 50 433, Part 3, or to a standard X-ray textbook. With
1. Scope
different wafer holding fixturing, Test Method B is also applicable to
1.1 These test methods cover the determination of a, the
determination of the orientation of a wafer surface.
angular deviation between the crystallographic orientation of
1.5 The values stated in inch-pound units are to be regarded
the direction perpendicular to the plane of a fiducial flat on a
as the standard. The values given in parentheses are for
circular silicon wafer, and the specified orientation of the flat in
information only.
the plane of the wafer surface.
1.6 This standard does not purport to address all of the
1.2 These test methods are applicable for wafers with flat
safety concerns, if any, associated with its use. It is the
length values in the range of those specified for silicon wafers
responsibility of the user of this standard to establish appro-
in SEMI Specification M 1. They are suitable for use only on
priate safety and health practices and determine the applica-
wafers with angular deviations of less than 65°.
bility of regulatory limitations prior to use. For specific hazard
1.3 The orientation accuracy achieved by these test methods
statements see Section 6.
depends directly on the accuracy with which the flat surface
can be aligned with a reference fence and the accuracy of the
2. Referenced Documents
orientation of the reference fence with respect to the X-ray
2.1 ASTM Standards:
beam.
E 82 Test Method for Determining the Orientation of a
1.4 Two test methods are covered as follows:
Metal Crystal
Sections
E 122 Practice for Choice of Sample Size to Estimate a
Test Method A—X-Ray Edge Diffraction Method 8 to 13
Test Method B—Laue Back Reflection X-Ray Method 14 to 18
Measure of Quality for a Lot or Process
F 26 Test Methods for Determining the Orientation of a
1.4.1 Test Method A is nondestructive and is similar to Test
Semiconductive Single Crystal
Method A of Test Methods F 26 except that it uses special
2.2 Military Standard:
wafer holding fixtures to orient the wafer uniquely with respect
MIL-STD-105D Sampling Procedures and Tables for In-
to the X-ray goniometer. The technique is capable of measur- 7
spection by Attributes
ing the crystallographic direction of flats to a greater precision
than the Laue back reflection method.
2.3 Other Standards:
1.4.2 Test Method B is also nondestructive, and is similar to
Code of Federal Regulations, Title 10, Part 20, Standards
Test Method E 82, and to DIN 50 433, Part 3, except that it 8
for Protection Against Radiation
uses“ instant” film and special fixturing to orient the flat with
SEMI Specification M 1, Polished Monocrystalline Silicon
respect to the X-ray beam. Although it is simpler and more 9
Slices
rapid, it does not have the precision of Test Method A because
DIN 50 433, Part 3, Testing of Materials for Semiconductor
it uses less precise and less expensive fixturing and equipment.
It produces a permanent film record of the test.
NOTE 1—The Laue photograph may be interpreted to provide informa-
Wood, E. A., Crystal Orientation Manual, Columbia University Press, New
tion regarding the crystallographic directions of wafer misorientation;
York, NY, 1963.
however, this is beyond the scope of the present test method. Users Barret, C. S., and Massalski, T. B., The Structure of Metals, 3rd edition
McGraw-Hill, New York, NY, 1966.
desiring to carry out such interpretation should refer to Test Method E 82
Annual Book of ASTM Standards, Vol 03.01.
Annual Book of ASTM Standards, Vol 14.02.
Annual Book of ASTM Standards, Vol 10.05.
Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700
These test methods are under the jurisdiction of ASTM Committee F01 on
Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.
Electronics and are the direct responsibility of Subcommittee F01.06 on Silicon
Published in Federal Register, Nov. 16, 1960. Available from Superintendent of
Materials and Process Control.
Documents, U.S. Government Printing Office, Washington, DC 20402.
Current edition approved Aug. 15, 1994. Published October 1994. Originally
Available from the Semiconductor Equipment and Materials Institute, Inc., 805
published as F847 – 83. Last previous edition F847 – 87.
E. Middlefield Rd., Mountain View, CA 94043.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
F 847
(a) Front and Side Views
(b) Photograph of Mounted Fixture (c) Detail of Wafer and Reference Fence
FIG. 1 Wafer Holding Fixture for X-Ray Edge Diffraction Method
Technology: Determining the Orientation of Single Crys- low-index plane, such as a {110} plane. In such cases the
6,10
tals Using the Laue Back-Scattering Method orientation of the flat may be described in terms of its angular
deviation from the low-index plane.
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
4. Significance and Use
3.1.1 orientation—of a single crystal surface, the crystallo-
4.1 The orientation of flats on silicon wafers is an important
graphic plane, described in terms of its Miller indices, with
materials acceptance requirement. The flats are used in semi-
which the surface is ideally coincident. The orientation of a
conductor device processing to provide consistent alignment of
wafer flat is the orientation of the surface of the flat (on the
device geometries with respect to crystallographic planes and
edge of the wafer). Flats are usually specified with respect to a
directions.
4.2 Either one of these test methods is appropriate for
10 process development and quality assurance applications. Until
Available from Beuth Verlag GmbH Burgrafenstrasse 4-10, D-1000 Berlin 30,
Germany. the interlaboratory precision of these test methods has been
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
F 847
FIG. 2 Schematic of the Diffraction Geometry for the X-Ray Edge Diffraction Method
FIG. 3 Photograph of Assembled View of Laue Camera and Wafer Holder
determined, it is not recommended that they be used between be unique. More often the flat surface will touch the reference
supplier and purchaser. fence along two lines perpendicular to the wafer surface at two
points. In this case, the orientation determined will be that of
5. Interferences
the plane through the two lines on the plane perpendicular to
5.1 The alignment of the flat against the reference fence
the wafer surface which passes through the two points. In the
may be affected by the straightness of the flat. In the unlikely
latter cases, the orientation determined is that which will be
event that the flat profile is convex, the flat orientation may not
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
F 847
FIG. 4 Photograph of Wafer Holding Fixture and Mounting Track
obtained in subsequent processing of the wafer when the to external X-radiation of quantum energy less than 3 MeV
−4
alignment is between the flat and a reference fence. over an indefinite period is 1.25 R (3.22 3 10 C/kg) per
−7
5.2 Misalignment of the various fixtures will degrade both calendar quarter (equivalent to 0.6 mR/h (1.5 3 10 C/kg·h))
the interlaboratory reproducibility and the absolute accuracy of as established in the Code of Federal Regulations, Title 10,
both test methods. The single-instrument repeatability will not Part 20. The present maximum permissible dose of hand and
be degraded provided the fixturing is rigid. forearm exposure under the same conditions is 18.75 R
−3
(4.85 3 10 C/kg) per calendar quarter (equivalent to 9.3
−6
6. Hazards
mR/h (2.4 3 10 C/kg·h)). Besides the above stated regula-
6.1 These test methods use X-radiation; it is absolutely tions, various other government and regulatory organizations
have their own safety requirements. It is the responsibility of
necessary to avoid personal exposure to X rays. It is especially
important to keep hands or fingers out of the path of the X rays the user to make sure that the equipment and the conditions
under which it is used meet these regulations.
and to protect the eyes from scattered secondary radiation. The
use of commercial film badge or dosimeter service is recom-
7. Sampling
mended, together with periodic checks of the radiation level at
the hand and body positions with a Geiger-Muller counter 7.1 Unless otherwise specified, Practice E 122 shall be used.
calibrated with a standard nuclear source. The present maxi- When so specified, appropriate sample sizes shall be selected
mum permissible dose for total body exposure of an individual from each lot according to MIL-STD-105D. Inspection levels
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
F 847
FIG. 5 Section of Laue Camera Platen Showing Light Pipe and Collimating Tube
shall be agreed upon between the parties to the test. 9.2.2 Both the side of the reference fence against which the
wafer flat is located, and the fixture surface to which the
TEST METHOD A—X-RAY EDGE
reference fence mates, must be flat to within one part per
DIFFRACTION METHOD
10 000.
8. Summary of Test Method
10. Procedure
8.1 In this test method a holding fixture which uniquely
10.1 Position the detector so that the angle between the
orients the wafer being tested with respect to its geometric
extension of the incident X-ray beam and the line joining the
features is used to position the wafers with r
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