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Selective Tungsten Silicide Deposition

IP.com Disclosure Number: IPCOM000062140D
Original Publication Date: 1986-Oct-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Emma, SA: AUTHOR [+3]

Abstract

This article relates generally to thin film deposition and, more particularly, to selective deposition of tungsten silicide by chemical vapor deposition and plasma etching. Refractory tungsten silicide can be selectively deposited by steps of chemical vapor deposition and plasma etching. This technique avoids the necessity of forming and removing a protective pattern to define deposition areas and is compatible with either CMOS or NMOS processing. Tungsten silicide is deposited generally over a substrate having surface areas of both polysilicon and silicon dioxide by using the reaction of silane and tungsten hexafluoride. The nucleation rate is slower on the silicon dioxide surface than on the polysilicon. Flow conditions can be adjusted to maximize this difference.

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Selective Tungsten Silicide Deposition

This article relates generally to thin film deposition and, more particularly, to selective deposition of tungsten silicide by chemical vapor deposition and plasma etching. Refractory tungsten silicide can be selectively deposited by steps of chemical vapor deposition and plasma etching. This technique avoids the necessity of forming and removing a protective pattern to define deposition areas and is compatible with either CMOS or NMOS processing. Tungsten silicide is deposited generally over a substrate having surface areas of both polysilicon and silicon dioxide by using the reaction of silane and tungsten hexafluoride. The nucleation rate is slower on the silicon dioxide surface than on the polysilicon. Flow conditions can be adjusted to maximize this difference. After a predetermined thickness of tungsten silicide has been reached on the silicon dioxide, the substrate is subjected to etching in a plasma of nitrofluoride until the silicon dioxide surfaces are free of tungsten silicide, a layer of which still remains on the polysilicon. The etching rate of tungsten silicide versus silicon dioxide can be increased by using a carrier gas, such as helium, with the nitrofluoride. The foregoing sequence of steps can be repeated until the required thickness of tungsten silicide has been achieved. The deposition rate of tungsten silicide can be increased by depositing a nucleation layer of metal on the polysilicon surfaces. Metal...