Browse Prior Art Database

Silver Metallurgy for Semiconductor Device

IP.com Disclosure Number: IPCOM000072871D
Original Publication Date: 1970-Oct-01
Included in the Prior Art Database: 2005-Feb-22
Document File: 2 page(s) / 57K

Publishing Venue

IBM

Related People

Pressman, FM: AUTHOR [+2]

Abstract

In the fabrication of semiconductor devices, it is often desirable to use nonreactive metals, such as silver and copper, as the primary interconnectors or stripes. Such metals present problems in multi-layer metallurgy which utilize a plurality of metal layers insulated by silicon dioxide. Because these nonreactive metals display poor adhesion to silicon and silicon dioxide, it is a customary practice to use layers of metals such as titanium or chromium, which have better adhesion to silicon and silicon dioxide, both above and below the silver stripe. Shown at A is a typical structure with titanium 10 under the silver 11 and chromium 12 above the silver. Because of the selective etching techniques involved, the sidewalls 13 of the silver stripe are usually uncovered.

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Silver Metallurgy for Semiconductor Device

In the fabrication of semiconductor devices, it is often desirable to use nonreactive metals, such as silver and copper, as the primary interconnectors or stripes. Such metals present problems in multi-layer metallurgy which utilize a plurality of metal layers insulated by silicon dioxide. Because these nonreactive metals display poor adhesion to silicon and silicon dioxide, it is a customary practice to use layers of metals such as titanium or chromium, which have better adhesion to silicon and silicon dioxide, both above and below the silver stripe. Shown at A is a typical structure with titanium 10 under the silver 11 and chromium 12 above the silver. Because of the selective etching techniques involved, the sidewalls 13 of the silver stripe are usually uncovered. This results in a deterioration at 14 of the applied upper SiO(2) or like insulating layer 15, as shown in B. This deterioration of the insulator along the sidewalls results in
1. poor insulation for the stripes,
2. undercutting of the stripes during subsequent etching steps

in the device fabrication, and
3. electrolytic migration of silver ions between stripes of

different voltage levels.

To insure complete enclosure of the sidewalls of the silver stripe with the covering metal, metal is applied to the sidewalls of the silver stripe in a separate operation. The top of the stripe is covered with a photoresist 16, as shown in C, after which additional coating...