Apparatus for detecting position of a notch in a semiconductor wafer
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United States of America Patent
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Aug 1, 1995
Grant Date -
N/A
app pub date -
Feb 2, 1993
filing date -
Feb 3, 1992
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
A semiconductor wafer placed on a table is rotated by a stepper motor stepwise by a broad pitch. At this time, a CCD line sensor transmits output signals to comparators. A CPU monitors output signals of the comparators and detects a notch formed in the wafer. After the notch is detected, the wafer is rotated stepwise by a fine pitch, and outer peripheral positional data of a notched region (outputs of an analog-to-digital converter) are sampled and stored in a RAM. The CPU computes a notch position from the outer peripheral positional data stored in the RAM. In this way, a V-shaped notch formed in a semiconductor wafer is detected speedily and with high precision.
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