Browse Prior Art Database

Integrated Circuit Fabrication Process

IP.com Disclosure Number: IPCOM000084417D
Original Publication Date: 1975-Nov-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Joshi, ML: AUTHOR [+2]

Abstract

United States Patent No. 3,841,926 teaches a method for producing a single-device memory cell using a capacitor in series with a field-effect transistor (FET). The gate of this type of device utilized a silicon oxide and silicon nitride composite insulating layer.

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Integrated Circuit Fabrication Process

United States Patent No. 3,841,926 teaches a method for producing a single-device memory cell using a capacitor in series with a field-effect transistor (FET). The gate of this type of device utilized a silicon oxide and silicon nitride composite insulating layer.

The following process teaches a comparable structure using platinum gate metal over a silicon oxide insulation layer. Fig. 1 illustrates N+ source and drain diffusions 1 and a P conductivity type silicon substrate 2. A portion of doped oxide 3 used to form the diffusions remains over one diffusion. Fig. 2 illustrates the formation of a gate oxide 5 covered with a layer of polycrystalline silicon 4 having superimposed thereon a layer of photoresist 6.

Fig. 3 shows the gate area etched, using a strong overetch, and platinum layer 7 deposited using the same photoresist mask utilized in opening the gate area in this step as a platinum lift-off mask, illustrated by 6 and 7. After the photoresist 6 is stripped, the polysilicon is thermally oxidized using platinum for passivation of the gate area forming oxide layer 8, as illustrated by Fig. 4. Adhesion between the platinum and silicon dioxide can be aided by using an intermediate layer of titanium or other suitable metal.

A further modification to the above process can be accomplished by starting with the configuration of Fig. 2, and forming a structure illustrated in Fig. 5 by etching the pattern shown in Fig. 5 into th...