Optical micrometer for measuring thickness of transparent wafers

Details Optical micrometer for measuring thickness of transparent wafers Optical micrometer for measuring thickness of transparent wafers

1996-05-03

1998-05-19

Font, Frank G.

Optics: measuring and testing

By dispersed light spectroscopy

Utilizing a spectrometer

356357, 356432, 356381, G01B 902

Patent

active

057542945

ABSTRACT:
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.

REFERENCES:
patent: 4773760 (1988-09-01), Makkonen
patent: 4984894 (1991-01-01), Kondo
patent: 5403433 (1995-04-01), Morrison et al.

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