Browse Prior Art Database

Detection of Etch Completion of Interconnection Metallurgy

IP.com Disclosure Number: IPCOM000077449D
Original Publication Date: 1972-Aug-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Gangulee, A: AUTHOR [+2]

Abstract

Variations in metal deposition processes lead to variation of thickness and quality of metal, in turn affecting etch rates across the wafer. Thus, the wafers must be brought out of the etch bath several times, rinsed, inspected for completion of metal etch and reinserted. This rinsing causes poor adhesion of existing photoresist in a subsequent etch cycle. The following method avoids the need to withdraw the wafer before etch completion and is suitable for automation.

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Detection of Etch Completion of Interconnection Metallurgy

Variations in metal deposition processes lead to variation of thickness and quality of metal, in turn affecting etch rates across the wafer. Thus, the wafers must be brought out of the etch bath several times, rinsed, inspected for completion of metal etch and reinserted. This rinsing causes poor adhesion of existing photoresist in a subsequent etch cycle. The following method avoids the need to withdraw the wafer before etch completion and is suitable for automation.

The method employs a test site on a metallized wafer to indicate completion of etching. The test site consists of two pad areas covered with photoresist with an exposed metal strip between them, as shown in the figure. The wafer is clamped at the pads by two insulated clips having sharp teeth which penetrate the photoresist and establish electrical contact with the pads. The wafer is then immersed in the etching bath or subjected to electron beam etching, and as soon as the exposed metal is etched away the electrical continuity between the two pads is broken signalling completion of etching. The clips preferably are covered with some pliable insulating material (e.g., neoprene, silicone rubber etc.) to insure that no etching takes place at the electrical contact points, and the etching bath should be stirred for uniform etching.

This method can also be used in the etching of other conducting layers such as doped polysilicon used for intercon...