Endpoint detection system and method for plasma etching

Details Endpoint detection system and method for plasma etching Endpoint detection system and method for plasma etching

1989-09-26

1990-09-04

Powell, William A.

Adhesive bonding and miscellaneous chemical manufacture

Delaminating processes adapted for specified product

Delaminating in preparation for post processing recycling step

156643, 156657, 156662, 156345, 20419233, 20429832, H01L 21306, B44C 122, C03C 1500, C03C 2506

Patent

active

049542125

ABSTRACT:
A plasma etching endpoint detection system and method for plasma etching systems generates an endpoint signal when the etching system completes the etching of a designated layer on a semiconductor wafer and begins etching the layer below the designated layer. An impedance transformation circuit is tuned so that the selected tuning point has a predefined relationship to the point at which minimum power reflection occurs. As a result, when the etching system completes the etching of a designated layer, the amount of power reflected by the plasma etcher will change in a predefined fashion so as to facilitate the generation of an endpoint signal. In one embodiment, a tuning capacitor in the etcher's impedance transformation circuit is set at a level at which it is known that the amount of reflected power will increase when the designated layer has been completely etched. As a result, the intensity of light generated in the plasma will decrease at the endpoint of etching the designated layer. An optical sensor, which is tuned to a frequency at which light is generated while the designated layer is being etched, generates an endpoint signal when the emission intensity decreases below a specified level, and that endpoint signal is used to turn off the etcher's plasma power supply. In another embodiment, the plasma etcher's controller detects when the reflected power increases above a specified level, at which point it generates an endpoint signal that is used to turn off the etcher's plasma power supply.

REFERENCES:
patent: 4207137 (1980-06-01), Tretola
patent: 4357195 (1982-11-01), Gorin

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