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SEMI MF1152-0305 © SEMI 2003, 2005 5 NOTICE: SEMI makes no warranties or represen tations as to the suitability o f the standards set forth herein for any particular application. The determination of the suitability of t…

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SEMI MF1152-0305 © SEMI 2003, 2005 4
10.5 Align the fixture using only table crossfeed (horizontal) control and fixture rotation so that the simulated pin
outline on the template makes contact with the sides of the notch image.
10.6 Verify that the image of the notch bottom falls on or below the NOTCH BOTTOM LIMIT line. If the image
of the notch bottom falls above this line, record the wafer as defective.
10.7 Verify that the image of the wafer edge falls on or above the WAFER PERIPHERY LIMIT line. If the image
of the wafer edge falls above this line, record the wafer as defective.
10.8 Move the fixture to the right until the image of the wafer edge falls on the line marked WAFER PERIPHERY
using only the table crossfeed control.
10.9 Verify that the notch bottom falls between the NOTCH MAX DEPTH and NOTCH MIN DEPTH lines. If the
image of the notch bottom falls outside these lines, record the wafer as defective.
10.10 Repeat ¶¶10.4 through 10.9 for all remaining wafers to be tested.
10.11 Remove the notch form and depth template and replace it with the notch angle template.
10.12 Set the magnification to 50×.
10.13 Place the first wafer to be tested in the fixture, front surface up.
10.14 Align the image of the wafer notch sides with each angle on the template using the table crossfeed control
and the fixture rotation. Define as the notch angle, the angle that provides the best fit to the image. If the notch
angle is < 89 or > 95°, record the wafer as defective.
10.15 Repeat ¶10.14 for all remaining wafers to be tested.
10.16 On completion of the testing, return the magnification to 20×.
11 Report
11.1 Report as a minimum the following information:
11.1.1 Date of test,
11.1.2 Name of person conducting the test,
11.1.3 The lot number of other identification of the material,
11.1.4 The number of wafers in the lot,
11.1.5 The number of test wafers, and
11.1.6 The number of defective wafers.
11.2 If desired, a table of the types of defects observed may be provided.
12 Precision and Bias
12.1 An interlaboratory evaluation of this test method has not been executed, nor is one anticipated. Use of the test
method for commercial transactions is not recommended unless the parties to the test establish the degree of
correlation that can be obtained.
12.2 A dimension of 0.1 mm in the object plane produces a screen image of 2.0 mm at 20× and of 5.0 mm at 50×.
The smallest size details of the notch contour which can be inspected by this test method are of comparable
dimensions.
13 Keywords
notch; notch dimension; optical comparator; silicon; wafer
SEMI MF1152-0305 © SEMI 2003, 2005 5
NOTICE: SEMI makes no warranties or representations as to the suitability of the standards set forth herein for any
particular application. The determination of the suitability of the standard is solely the responsibility of the user.
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Copyright by SEMI® (Semiconductor Equipment and Materials
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consent of SEMI.
SEMI MF1188-0305 © SEMI 2003, 2005 1
SEMI MF1188-0305
TEST METHOD FOR INTERSTITIAL OXYGEN CONTENT OF SILICON
BY INFRARED ABSORPTION WITH SHORT BASELINE
These test methods were technically approved by the Global Silicon Wafer Committee and are the direct
responsibility of the North American Silicon Wafer Committee. Current edition approved for publication by
the North American Regional Standards Committee December 10, 2004 Initially available at
www.semi.org
January 2005; to be published March 2005. Original edition published by ASTM International as ASTM F
1188-88. Last previous edition SEMI MF1188-02.
INTRODUCTION
Prior to 2002, ASTM Test Method F 1188 used a long baseline for the 1107 cm
1
oxygen
absorption peak. This long baseline was drawn between the average transmittances in the regions
from 900 to 1000 cm
1
and from 1200 to 1300 cm
1
. The same baseline was used in ASTM Test
Method F 121, the predecessor to Test Method F 1188, and also in the analysis of infrared data
from the Grand Round Robin (GRR) experiment.
1
The GRR experiment resulted in a calibration
factor between the infrared absorption coefficient at 1107 cm
1
and the absolute interstitial oxygen
content known as “IOC-88.” This calibration factor is utilized in the current editions of all known
standardized test methods for oxygen content of silicon, including DIN 50438, Part 1; and JEITA
EM-3504; as well as the current Chinese National Standard (GB).
The long baseline method is being retained in the form published in the 1993a edition of this test
method in Appendix 1. However, the long baseline is subject to uncertainties due to perturbations
in the IR absorption at the end-point regions arising from effects other than absorption by
interstitial oxygen. Use of a shorter baseline, drawn between 1040 and 1160 cm
1
, which is less
affected in this manner,
2
results in improved precision of the method. Use of the shorter baseline
is introduced into this test method to replace the long baseline method. Although the use of this
baseline results in a somewhat smaller net absorption coefficient for the same oxygen content, this
change is not very large, and can be neglected in most cases. Optionally, to completely eliminate
the effect of the baseline changes, the measurement equipment may be calibrated with suitable
certified reference materials (CRMs) or reference materials derived from CRMs.
NIST SRM
3
2551 oxygen-in-silicon reference material,
4,5
which is the principal CRM used for
calibrating commercial infrared spectrophometers for oxygen measurements, was certified using a
subset of the GRR specimens as the absolute references. Both the GRR specimens and the SRM
specimens were measured using a short baseline similar to that now incorporated in this test
method. This resulted in (1) reduced measurement uncertainty for the SRM specimens, and (2) a
strong metrological foundation provided by the GRR specimens. Consequently, the IOC-88
results are available to the users of the SRMs without requiring a change in the calibration factor
even though the short-baseline method is used.
1 Baghdadi, A., Bullis, W. M., Coarkin, M. C., Li Yue-zhen, Scace, R. I., Series, R. W., Stallhofer, P., and Watanabe, M., “Interlaboratory
Determination of the Calibration Factor for the Measurement of the Interstitial Oxygen Content of Silicon by Infrared Absorption,” J.
Electrochem. Soc. 136, 2015–2034 (1989). Baghdadi, A., Scace, R. I., and Walters, E. J., “Semiconductor Measurement Technology: Database
for and Statistical Analysis of the Interlaboratory Determination of the Calibration Factor for the Measurement of the Interstitial Oxygen Content
of Silicon by Infrared Absorption,” NIST Special Publication 400-82, July 1989.
2 Series, R. W., “Determination of Oxygen and Carbon in Silicon,” RSRE Memorandum No. 3479 (Royal Signals & Radar Establishment,
Malvern, Worcs, UK, 1982).
3 SRM is a registered trademark of the National Institute of Standards and Technology.
4 Available as a set of four 25 mm square, 2 mm thick, silicon specimens, mirror polished on both sides. One of the specimens is a high
resistivity float zoned specimen with negligible oxygen content. The other three specimens were cut from n-type crystals grown by a modified
Czochralski process. Their room temperature resistivity is > 3 ·cm, and they have nominal oxygen content of 17, 23, and 26 parts per million
atomic (IOC-88). The specimens are mounted on aluminum disks for ease of use in production spectrophotometers.
5 Details of the certification of this SRM are given in Rennex, B. G., “Standard Reference Materials: Certification of a Standard Reference
Material for the Determination of Interstitial Oxygen Concentration in Semiconductor Silicon by Infrared Spectrophotometry,” NIST Spec. Publ.
260-121 (Aug. 1994).