In-Situ Cap Polysilicon for CVD Silicide
Original Publication Date: 1988-May-01
Included in the Prior Art Database: 2005-Feb-15
To protect chemically vapor deposited (CVD) tungsten silicide (WSi2) films from degradation by oxidation, particularly at low film density regions where the film is formed over sharp steps on the substrate, a layer of poly crystalline silicon (Poly Si) is normally deposited in another, higher temperature CVD processor. By utilizing a radio frequency (RF) power supply normally used for a tool cleaning process, the tool is converted to a plasma enhanced mode (PECVD) capable of depositing Poly Si at the lower temperature of the WSi2 CVD tool. Thus, following the normal CVD WSi2 deposition, tungsten hexafluoride gas flow is stopped (continuing flow of silane), RF is applied and the film of Poly Si is deposited in situ.