Quantitative Analysis of Etching Damage in the Highly-Selective Oxide Etching

The damage produced by the oxide dry etching process was quantified by the Time of Flight-Low Energy Ion Scattering Spectroscopy, paying special attention to the crystalline degradation and to the contamination. The highly selective oxide dry etching process, in which CO gas is added to the C4F8 gas produced a damaged layer of more than 10.0 nm thickness. This layer contains abundant Si-C and Si-O bonds. These make it difficult to remove the damaged layer by post treatment, and suppress the lifetime recovery. In case of conventional contact hole etching process using CF/sub 4/ / CHF/sub 3/ gas, the damaged layer contains less Si-C, Si-O bonds although the layer thickness is more than 10nm.