Very High Frequency Plasma Enhanced Chemical Vapor Deposition of TiSix/TiN1-xSix Barrier Films

Abstract

Very high frequency plasma enhanced chemical vapor deposition (VHF-PECVD) of titaniumsilicide /titaniumnitride barrier films using the silane reduction process with a TiCl4 source is described. VHF plasma, which is denser than a conventional RF plasma, produces a large number of excited species. The silane reduction process, which supplies excited species such as SiHx radicals and SiHx + ions as reductants in plasma, promotes dissociation of TiCl4 precursors more than a conventional hydrogen reduction process. Therefore, the VHF-PECVD with the silane reduction process forms high quality titaniumsilicide/titaniumnitride barrier films, which have a low Cl content (<0.2 at.%). In the silane reduction process, the Ti–Si bond is simultaneously formed into the bond structure, resulting in depositing Si-containing films of TiSix or TiN1-x Six . The resistivity of TiSix or TiN1-x Six is about 100 µ Ω· cm. The surface morphology of TiSix films is very smooth and the structure of TiN1-x Six films is amorphous.