Restoration of plasma damaged porous ultra low-k SiOCH films: A coating process with UV activation versus a vapor phase process with thermal activation

Two processes to repair plasma damaged porous ultra low- SiOCH dielectric were studied. One process is based on a spin on approach in combination with UV radiation. The second process uses a vapor phase reaction chamber, while the silylation reaction is thermally activated. Comparison of both processes was achieved by applying four different silylation agents. After processing of blanket wafers, the restoration performance was characterized by different analytical techniques like Fourier transformed infrared and Auger electron spectroscopy as well as contact angle and mercury probe measurements. Electrical tests on patterned wafers were carried out only for the spin on UV process. Both repair approaches show variable restoration performance, while the vapor phase process seems to be favorable. It is suggested that the reason for this advantage is related to a continuous chemical delivery and a better diffusion behavior of chemicals at elevated temperatures. Restoration of the surface free energy and partial recovery of the -value was obtained for both processes. This suggests that the supported energy, i.e. by UV or high temperature, is sufficient to activate the silylation reaction