Browse Prior Art Database

Capped Copper Lift Off Process for Semiconductor Devices

IP.com Disclosure Number: IPCOM000079035D
Original Publication Date: 1973-Apr-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 67K

Publishing Venue

IBM

Related People

Gegenwarth, RE: AUTHOR [+5]

Abstract

Lift-off processes for the selective removal of material, without chemically etching the material, are facilitated by the use of an interlayer which is etched back to provide a substantial overhang of the overlying material, adjacent the areas where it is to be selectively removed. Copper is a suitable interlayer material, but requires the use of a capping material to prevent contamination of underlying semiconductor substrate. Suitable capping materials include aluminum, copper or chromium.

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Capped Copper Lift Off Process for Semiconductor Devices

Lift-off processes for the selective removal of material, without chemically etching the material, are facilitated by the use of an interlayer which is etched back to provide a substantial overhang of the overlying material, adjacent the areas where it is to be selectively removed. Copper is a suitable interlayer material, but requires the use of a capping material to prevent contamination of underlying semiconductor substrate. Suitable capping materials include aluminum, copper or chromium.

In Fig. 1, a thin capping layer of aluminum-copper 1 is placed over apertured silicon dioxide 2 on silicon substrate 3. 500 to 1,000 angstroms is an adequate thickness for layer 1. About 10,000 angstroms of copper 4 is deposited over layer 1 and a photoresist layer 5 is placed over copper layer 4. Photoresist 5 is exposed selectively and developed, so as to remove the photoresist from areas 6 overlying the apertures in oxide layer 2. The copper is etched using the developed photoresist as a mask to provide the structure shown in Fig. 1.

Conductive material, for example, a suitable thickness of aluminum-copper 7 is deposited over the structure of Fig. 1, as shown in Fig. 2. It should be noted that etched copper layer 4 provides a substantial overhang of the photoresist layer 5, which facilitates the removal of aluminum-copper layer 7 during lift-off. Lift-off is accomplished by removing photoresist layer 5, and with it,...