Virginia Semiconductor, Inc.

Thomas Digges

Stephen H Jones

Robert A Ross

Carolyn DeMain

David Abdallah

Techniques and systems for measuring absolute thickness, the total thickness variation, and electric resistivity of a semiconductor wafer in a nondestructive optical fashion. Optical absorption is used to measure the absolute thickness of a semiconductor wafer with a light source and a phototransceiver. The thickness is determined by comparing the amount of absorption to a calibrated amount. Coherent light interference is used to measure the total thickness variation of a substrate. Alternatively, both the absolute thickness and total thickness variation of the substrate can be measured based on light absorption using a CCD imaging device. The resistivity of a wafer sample can also be measured by using an alternating electrical signal.

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Fredericksburg, VA, United States of America

Thomas Digges