Physical and barrier properties of plasma-enhanced chemical vapor deposited alpha-SiC : H films from trimethylsilane and tetramethylsilane

Abstract

This work investigates the thermal stability and physical and barrier properties of two species of plasma-enhanced chemical vapor deposited (PECVD) alpha-SiC:H silicon carbide films (with k-values less than 5) deposited using trimethylsilane, (CH3)(3)SiH (3MS) and tetramethylsilane, (CH3)(4)Si (4MS) organosilicate gases. It is found that the 4MS alpha-SiC:H film contains a higher content of carbon and has a lower dielectric constant. Both of the 3MS and 4MS alpha-SiC:H films are thermally stable at temperatures up to 500degreesC. However, degraded barrier property and moisture resistance were observed for the 4MS alpha-SiC:H film; this is attributed to the porosity enrichment caused by the film's high carbon content. The 3MS alpha-SiC:H film, which exhibits a superior Cu-barrier property, is a potential candidate for replacing the higher dielectric constant Si3N4 film as a Cu-cap barrier and etching stop layer in the Cu damascene structure.