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Process For Reactive Ion Etching of Polycide

IP.com Disclosure Number: IPCOM000048463D
Original Publication Date: 1982-Feb-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Bennett, RS: AUTHOR [+3]

Abstract

A two-step process for selectively etching a polycide (silicide plus polysilicon) structure (Fig. 1A) to a gate oxide in a two-electrode reactive ion etching system has been developed. In the first step, reactive ion etching is used to control line width as well as the etch profile of silicide (WSi(2)). In the second step, plasma etching is used to stop at the underlying oxide.

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Process For Reactive Ion Etching of Polycide

A two-step process for selectively etching a polycide (silicide plus polysilicon) structure (Fig. 1A) to a gate oxide in a two-electrode reactive ion etching system has been developed. In the first step, reactive ion etching is used to control line width as well as the etch profile of silicide (WSi(2)). In the second step, plasma etching is used to stop at the underlying oxide.

In the first step, the silicide layer and about 1000 Angstrom of the polysilicon layer are etched in 100 micrometers CF/4/ plus 40 percent 0(2) with 0.27 W per sq cm RF power applied to the substrate electrode. During the second step, the same pressure, gas mixture and power density are used except that power is applied to the counterelectrode. During the second step, the n+ polysilicon to silicide etch rate ratio is about 2 to 1; however, undercutting of the silicide layer is minimal because the silicide was pulled back during the first step.

Fig. 1B illustrates the finished polycide structure. The two-step process provides a controllable and reproducible etch rate ratio. Further, both steps may be carried out in the same two-electrode reactive ion etching system.

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