End point detection in etching wafers and the like

Details End point detection in etching wafers and the like End point detection in etching wafers and the like

1980-11-13

1982-03-02

Powell, William A.

Adhesive bonding and miscellaneous chemical manufacture

Delaminating processes adapted for specified product

Delaminating in preparation for post processing recycling step

156345, 156639, 156640, 356445, C23F 102

Patent

active

043176984

ABSTRACT:
A method for detecting the end point of etching wafers and the like by reflective means. Typically, a detected reflectance signal will have a threshold level representing a lack of substantial etching, a dip in the threshold level representing the commencement of etching and an inflection level representing a maximum rate of light amplitude change. The present method involves subtracting the inflection level from the threshold level and taking a predetermined fraction of the resultant level to define a second threshold level further in the etch cycle which anticipates the end of the cycle. By observational experience, the predetermined fraction can be determined. As soon as the second threshold level is reached, brakes are applied to the etching process so that etching will cease shortly after the predetermined level has been identified. In this manner, the actual end of etching will coincide with the attainment of a desired etching condition, such as removal of a layer of undesired metalization, without significant overshoot.

REFERENCES:
patent: 4068016 (1978-01-01), Wilmanns
patent: 4161356 (1979-07-01), Giffin et al.
patent: 4198261 (1980-04-01), Busta et al.
patent: 4208240 (1980-07-01), Latos
IBM Technical Disclosure Bulletin, vol. 21, No. 3, Aug. 1978, Multiple Optical End-Point Detector by B. H. Desilets, pp. 1035-1037.

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