Effect of plasma treatments on interface chemistry and adhesion strength between porous SiO2 low-k film and SiC/SiN layers

In this study, the interface chemistry and adhesion strengths between porous SiO2 low-dielectric-constant film and SiN capping layer as well as SiC etch stop layer have been investigated under different plasma treatments. Elements of Si, O, and N constructed an interlayer region with mixing Si–N and Si–O bonds at the interface between the porous SiO2 film and SiN capping layer. After plasma treatments especially O2 plasma, the oxygen content at the interface increased, and the binding energy obviously shifted to a higher level. Under nanoindentation and nanoscratch tests, interface delamination occurred, and the interface adhesion strength was accordingly measured. After plasma treatments especially the O2 plasma, more Si–O bonds of high binding energy existed at the interface, and thus the interface adhesion strength was effectively improved. The adhesion energy of SiO2/SiN and SiC/SiO2 interfaces was enhanced to 4.7 and 10.5 J/m2 measured by nanoindentation test, and to 1.3 and 2.0 J/m2 by nanoscratch test, respectively.