Effect of plasma treatments on interface adhesion between SiOCH ultra-low-k film and SiCN etch stop layer

The effect of different plasma treatments on the interfacial bonding configurations and adhesion strengths between porous SiOCH ultra-low-dielectric-constant film and SiCN etch stop layer have been investigated in this study. From X-ray photoelectron spectroscopic analyses, interlayer regions of about 10 nm thick with complicated mixing bonds were found at SiOCH/SiCN interfaces. With plasma treatments, especially H2/NH3 two-step plasma, a carbon-depletion region of about 30 nm thick with more Si–O related bonds of high binding energy formed at the interface. Furthermore, the adhesion strengths of the SiOCH/SiCN interfaces were measured by nanoscratch and microscratch tests. For the untreated interface, the adhesion energy was obtained as about 0.22 and 0.44 J/m2 by nanoscratch and microscratch tests, respectively. After plasma treatments, especially the H2/NH3 treatment, the interfacial adhesion energy was effectively improved to 0.41 and 0.89 J/m2 because more Si–O bonds of high binding energy formed at the interfaces.