Optoelectric multi-sensor measuring apparatus and a method for m

Details Optoelectric multi-sensor measuring apparatus and a method for m Optoelectric multi-sensor measuring apparatus and a method for m

1977-09-13

1979-09-18

Nelms, David C.

Radiant energy

Photocells; circuits and apparatus

Optical or pre-photocell system

356 1, G01N 2130

Patent

active

041684370

ABSTRACT:
The method for efficiently measuring the thickness or surface flatness of, for example, a high-purity silicon semiconductor wafer uses a table to mount the wafer and a plurality of optoelectric sensors, each sensor being movable in the direction perpendicular to the table. The sensors are designed to project light beams to the measuring points set forth on the wafer surface. The light beam reflected from each measuring point is detected by a detector there. To the detector is connected a photoelectric transducer which generates electric signals corresponding to the distance of each measuring point from a reference surface, so that thickness variations can be found. In a preferred embodiment, the sensors are arranged in linear rows at regular intervals and the wafer surface is scanned with the light beams so that all measuring points distributed lattice-wise at regular intervals on the wafer surface are covered. The thickness variations of the wafer may be put in a computer which is connected to the measuring apparatus.

REFERENCES:
patent: 3667846 (1972-06-01), Nater et al.
patent: 3671126 (1972-06-01), Erb
patent: 3817619 (1974-06-01), Kawahara
patent: 3897156 (1976-07-01), Chasson

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