Effects of Plasma Exposure on SiCOH and Methyl Silsesquioxane Films

Abstract

The effects of plasma exposure (O2, Ar, H2, and CF4) on the surface chemistries, surface energies, and dielectric constants, k, of two low-k SiCOH films (BD-1 and BD-2) and a methyl silsesquioxane (MSQ) control are described. Relatively non-polar, low surface energy MSQ and BD-2 exhibited significant changes when exposed to various plasmas: carbon depletion, oxygen enhancement, and increased surface energy. The higher surface energy BD-1 has a more extensive SiOSi network structure, which was relatively insensitive to plasma exposure. BD-1's relatively low k is indicative of a porous material. While most plasmas produced an increase in k, deposition of CFn species as a result of exposure to a CF4 plasma caused a slight decrease in k. The increase in k corresponded to an increase in the dispersive surface energy component.