Optical micrometer for measuring thickness of transparent substrates based on optical absorption
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United States of America Patent
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Sep 28, 1999
Issued Date -
N/A
app pub date -
Oct 29, 1997
filing date -
May 3, 1996
priority date (Note) -
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Abstract
Techniques and systems for measuring absolute thickness, the total thickness variation, and electric resistivity of a semiconductor substrate in a nondestructive optical fashion. Optical absorption is used to measure the absolute thickness of a semiconductor substrate with a light source and a photo transceiver. The thickness is determined by comparing the amount of absorption to a calibrated amount. Both the absolute thickness and total thickness variation of the substrate can be measured based on light absorption using an imaging device. The invention can be used to directly image and measure localized features formed on micro machined substrates. The resistivity of a substrate sample can also be measured by using an alternating electrical signal.
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