A method of RIE treatment to enhance the contour of CoSi2/TiSi2 for profile analysis

In VLSI technology, CoSi₂/TiSi₂ configuration is used as a glue layer to reduce contact resistivity. The quality of CoSi₂/TiSi₂ conformation and remaining of CoSi₂/ TiSi₂ thickness after contact etching process are the key parameters in IC processing. Traditionally, wet etching treatment is usually used to monitor CoSi₂/TiSi₂ profile. In order to enhance the CoSi₂/TiSi₂ contour contrast to measure the silicide layer remaining thickness and monitor CoSi₂/TiSi₂ 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 CoSi₂/TiSi₂ conformation and contour than wet etching treatment. Second, dry mode has wider etching time window than wet mode. Third, Ar gas only or decreasing CHF₃ gas flow can get better contrast All of the silicide profiles were checked by SEM