A method of RIE treatment to enhance the contour of CoSi/sub 2//TiSi/sub 2/ for profile analysis

Abstract

In VLSI technology, CoSi/sub 2//TiSi/sub 2/ configuration is used as a glue layer to reduce contact resistivity. The quality of CoSi/sub 2//TiSi/sub 2/ conformation and remaining of CoSi/sub 2// TiSi/sub 2/ thickness after contact etching process are the key parameters in IC processing. Traditionally, wet etching treatment is usually used to monitor CoSi/sub 2//TiSi/sub 2/ profile. In order to enhance the CoSi/sub 2//TiSi/sub 2/ contour contrast to measure the silicide layer remaining thickness and monitor CoSi/sub 2//TiSi/sub 2/ conformation, wet etching treatment solvent component, concentration and treated time are the major recipe controlling parameters. The other way of silicide profile contrast enhancement is by using dry RIE plasma etching treatment. Compared with wet approach, three items were concluded. First, increasing ion bombardment by decreasing total pressure can produce much clear CoSi/sub 2//TiSi/sub 2/ conformation and contour than wet etching treatment. Second, dry mode has wider etching time window than wet mode. Third, Ar gas only or decreasing CHF/sub 3/ gas flow can get better contrast All of the silicide profiles were checked by SEM.