In-situ after-treatment using low-energy dry-etching with a CF4/O2 gas mixture to remove reactive ion etching damage

We have investigated a new method of in-situ after-treatment that precisely and anisotropically removes dry-etching damage induced by reactive-ion etching (RIE) of SiO2, especially in self-aligned contact (SAC) processing, through, low-energy etching in the dry-etching chamber after the RIE. This in-situ after-treatment with a CF4/Ar gas mixture and with a CF4/O-2 gas mixture were examined. The after-treatment with the CF4/O-2 gas almost completely removed both the chemical damage and the crystalline damage. On the other hand, although RIE damage could be reduced by after-treatment with the CF4/Ar gas mixture. severe crystal damage remained. The after-treatment with the CF4/O-2 gas mixture could precisely remove the surface damage and allowed us to control the surface roughness during removal of RIE damage.