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Determining Etch End Point in Plasma Etching of Via Holes

IP.com Disclosure Number: IPCOM000086303D
Original Publication Date: 1976-Aug-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Alcorn, GE: AUTHOR

Abstract

A method is described for determining the etching end point in the plasma etching of a via hole through a quartz layer to an aluminum conductor on a silicon substrate.

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Determining Etch End Point in Plasma Etching of Via Holes

A method is described for determining the etching end point in the plasma etching of a via hole through a quartz layer to an aluminum conductor on a silicon substrate.

The figure shows the silicon substrate 2 upon which is deposited an aluminum electrode 4, to which electrical contact is to be made. Overlying the aluminum layer 4 is a quartz layer 6 which covers both the aluminum layer 4 and the silicon substrate 2, in regions not covered by the aluminum layer 4. To delineate the regions where etching is to take place, a photoresist layer 8 is deposited over the quartz layer 6 and opening 10 is formed therein at a location corresponding to the desired via hole 14 over the aluminum electrode 4.

Since the quartz layer 6 is optically transparent, it is not possible to determine when the end point for the etching of the via hole 14 takes place. Thus it is a feature of this method to form a second opening 12 in the photoresist layer 8 over the region of the silicon substrate 2 not covered by the aluminum electrode 4, so that a second via hole 16 may be formed during the reactive plasma etching step for the formation of the via hole 14.

The motivation for the formation of this second via hole 16, is the recognition of the fact that silicon etches at a much faster rate in a reactive plasma etching chamber than does aluminum. Utilizing this differential etching phenomenon, when the reactive plasma etches through t...