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Anisotropic and Selective Etching of Tungsten Silicide-Tungsten- Tungsten Silicide Composite Stack

IP.com Disclosure Number: IPCOM000061506D
Original Publication Date: 1986-Aug-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Cronin, JE: AUTHOR [+3]

Abstract

This article discusses an etch chemistry that improves etch selectivity and eliminates preferential attacks of a tungsten silicide-tungsten- tungsten silicide stack during a reactive ion etch (RIE). The figure shows a composite film structure of tungsten silicide (WSix), tungsten (W) and tungsten silicide with a mask on top and a narrow-dimensioned topographical feature on the substrate below. Highly anisotropic and selective etching of CVD (chemical vapor deposited) W/WSix films can be achieved using admixtures of SiF4 and O2 as etch gasses. It is generally accepted that W and Si etching occurs in plasma systems by a combination of the etched materials with atomic fluorine. Volatile fluoride products form and are pumped away, e.g., WF6 or SiF4 . Thus, the RIE species is fluorine.

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Anisotropic and Selective Etching of Tungsten Silicide-Tungsten- Tungsten Silicide Composite Stack

This article discusses an etch chemistry that improves etch selectivity and eliminates preferential attacks of a tungsten silicide-tungsten- tungsten silicide stack during a reactive ion etch (RIE). The figure shows a composite film structure of tungsten silicide (WSix), tungsten (W) and tungsten silicide with a mask on top and a narrow-dimensioned topographical feature on the substrate below. Highly anisotropic and selective etching of CVD (chemical vapor deposited) W/WSix films can be achieved using admixtures of SiF4 and O2 as etch gasses. It is generally accepted that W and Si etching occurs in plasma systems by a combination of the etched materials with atomic fluorine. Volatile fluoride products form and are pumped away, e.g., WF6 or SiF4 . Thus, the RIE species is fluorine. Careful selection of process conditions (temperature, power density, pressure and gas flow rates) eliminates any selective attack of the silicide layers. Vertical sidewalls may be etched with a single wafer RIE tool at nominal pressures, temperatures and power densities using the following gas flow rates: SiF4 100 - 200 sccm O2 13 - 17 sccm

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