Browse Prior Art Database

Fusion of Silicon Wafers

IP.com Disclosure Number: IPCOM000087542D
Original Publication Date: 1977-Feb-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Brock, GE: AUTHOR [+4]

Abstract

For a variety of dielectric isolation techniques, one silicon wafer may be fused to another at a particular step. It would, of course, be desirable to have the capability of fusing such wafers together at moderate temperatures and with minimal time cycles. Wafers may be fused together conveniently by forming a layer of silicon dioxide on each wafer, then placing the layers of silicon dioxide abutting each other, and heating, preferably in a steam atmosphere at a temperature in the order of 1050 degrees C for about one-half hour. This time-temperature cycle may be reduced through a variety of expedients.

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Fusion of Silicon Wafers

For a variety of dielectric isolation techniques, one silicon wafer may be fused to another at a particular step. It would, of course, be desirable to have the capability of fusing such wafers together at moderate temperatures and with minimal time cycles. Wafers may be fused together conveniently by forming a layer of silicon dioxide on each wafer, then placing the layers of silicon dioxide abutting each other, and heating, preferably in a steam atmosphere at a temperature in the order of 1050 degrees C for about one-half hour. This time- temperature cycle may be reduced through a variety of expedients.

For example, the fusion temperature may be reduced by forming a thin layer of phosphosilicate glass or borosilicate glass 12 and 13 on the surfaces of silicon dioxide layers 10 and 11 (Fig. 1). This may be to the fusion step to make these layers hydrophilic, and then depositing a small amount of either boric acid solution (saturated aqueous boric acid solution) or dilute phosphoric acid solution on either or both of the layers 10 and 11. This will result in a thin layer of either boro-silicate or phosphosilicate glass being formed on the surface of the silicon dioxide layers during the heat treatment for fusion. These glasses may also be formed by doping with boron or phosphorus in the conventional manner.

When such a thin borosilicate or phosphosilicate glass layer is formed on the surface, the fusion step may then be carried out at a lo...