Analyses of interface adhesion between porous SiOCH low-k film and SiCN layers by nanoindentation and nanoscratch tests

In this study, an Si/PEOX/SiCN/SiOCH/SiCN multilayered film stack has been prepared by chemical vapor deposition. The bonding configurations between porous SiOCH film and SiCN etch stop layers have been analyzed by X-ray photoelectron spectroscopy, and the interface adhesion has been investigated by nanoindentation and nanoscratch tests. Elements of Si, C, N, and O constructed an interlayer region of about 10 nm with mixing bonds of Si to C, Si to N and Si to O at the interface between the porous SiOCH film and SiCN layers. During nanoindentation and nanoscratch tests, interface delamination occurred between SiOCH and SiCN layers due to the accumulation of sufficient shear stresses around the indented regions. The interface adhesion energy was accordingly measured as 1.68 J/m2 by nanoindentation test with an applied load of 30 mN. With higher applied loads, the measured interface adhesion energy decreased. By the nanoscratch test, the interface adhesion energy was measured as about 0.91 J/m2, lower than that obtained by nanoindentation test due to the mode mixity effect.