The effects of surface-plasma treatment of thin-film hydrogen silesquioxane low k dielectric

Abstract

Hydrogen silesquioxane (HSQ) is a low dielectric constant material and a potential substitute for conventional silicon dioxide insulator in ULSI system. In this study, the effect of plasma treatment on HSQ films is investigated. The bond structure changes of HSQ after curing, plasma treatment, and water absorption were observed with Fourier transform infrared spectroscopy. Densification of the film occurs after curing, the higher the curing temperature, the lower the dielectric constant and refractive index of the film. Both H₂- and O₂-plasma treatments are employed in this study. The H₂-plasma bombardment enhances the formation of the network structure but raises the moisture absorption of HSQ films. It is found that films subjected to both H₂- and O₂-plasma treatments have lower dielectric constant than those subjected to O₂ treatment alone. Possible mechanisms for the effects of plasma treatments are explored. The residual stress of HSQ film is also studied.