Analyses of interface adhesion between porous SiO2 low-k film and SiC/SiN layers by nanoindentation and nanoscratch tests

In this study, the interface adhesion between porous SiO2 low-dielectric-constant film and SiN capping layer as well as SiC etch stop layer has been investigated. The SiN capping layer was found mostly composed of Si to N bonds, and the porous SiO2 film composed of Si to O bonds. Elements of Si, O, and N constructed an interlayer mixing region of about 20 nm at the interface between the porous SiO2 film and SiN capping layer. Under nanoindentation and nanoscratch tests, interface delamination between the porous SiO2 film and both SiN capping layer and SiC etch stop layer occurred around the indented regions, and the interface adhesion strengths were accordingly obtained. The interface adhesion energy between the porous SiO2 film and SiN capping layer was measured as about 3.7 and 0.9 J/m2 by nanoindentation and nanoscratch tests, respectively, and that between the porous SiO2 film and SiC etch stop layer was about 8.3 and 1.2 J/m2.