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Metal Gate Structure Compatible with High Temperature Oxidation Processes

IP.com Disclosure Number: IPCOM000037863D
Original Publication Date: 1989-Aug-01
Included in the Prior Art Database: 2005-Jan-30
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Cronin, JE: AUTHOR

Abstract

Through the use of selective silicon deposition on exposed metal gate structures, a self aligned, oxidation resistive silicide is formed.

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Metal Gate Structure Compatible with High Temperature Oxidation Processes

Through the use of selective silicon deposition on exposed metal gate structures, a self aligned, oxidation resistive silicide is formed.

Because of their low resistivities, refractory metals, like Tungsten (W), have been used as gate electrodes. However, refractory metal gate electrodes have had limited use due to their poor oxidation resistance. Previous methods to make the refractory metal gate structure oxidation resistive have not been employed due to the complexity of the extra processing steps involved.

A W metal gate structure (2) is defined on gate oxide (1). Low temperature selective silicon (3) is deposited on the W metal gate (2). The selective silicon process (in the order of 300 degrees C), deposits on the W gate (2) and not on the gate oxide (1). It is critical that the selective silicon deposition temperature be low, so as to prevent oxidation of the W gate (2). An anneal is performed to react all the Si with the W forming a W-silicide (WSi2) (4). The WSi2 (4) acts as an oxidation resistance barrier.

The subsequent high temperature processing normally employed will not oxidize the WSi2 protective coating. The added WSi2 protective cap does not degrade any of the W gate properties.

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Disclosed anonymously.

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