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Selected wafers from a crystal are notched to permit the order of the wafers to be reestablished for characterization studies.
English (United States)
This text was extracted from a PDF file.
This is the abbreviated version, containing approximately
87% of the total text.
Page 1 of 1
Wafer Identification Notching Scheme
Selected wafers from a crystal are notched to permit the order of the wafers
to be reestablished for characterization studies.
In order to properly characterize entire single crystal ingots for material
characteristics, it is usually necessary to provide data on wafers chosen from
particular sections of the grown crystal. Since the wafers from a given crystal are
randomly mixed at some processing operations, it is necessary to identify the test
wafers by some method.
The following scheme accomplishes this task. The identification scheme
involves placing a small notch on the periphery of the test wafers. The position
of the notch is moved around the periphery by rotating the sample wafers in a
notching fixture by equal angular displacement. The notch placement occurs
immediately after the crystal-slicing operation because the entire lot of wafers is
still in numerical sequence, and the desired sample spacing (i.e., one wafer from
each successive cm (or inch), etc.) can be selected easily.
The notch is placed on the wafer periphery by positioning the sample wafers
in a standard plastic wafer carrier and utilizing a small outer-diameter cutting
wheel. Typical notch dimensions are 1/64'' wide by 3/32'' deep. These
dimensions are sufficiently small to allow the notched wafer to be reinserted in
the wafer lot and processed through all subsequent processing steps, yet large
enough to allow the notched wafer to be identified and remov...