Influence of carbon monoxide gas on silicon dioxide dry etching

Abstract

For narrow gap reactive ion etching (RIE) of SiO 2 using CF 4, CHF 3 and Ar chemistry at a pressure range of 30 to 70 Pa, we found that a higher selectivity of Si can be obtained by adding CO gas to the plasma. Our optical plasma emission spectrum data showed that not only C atoms but also C + ions were produced by this addition of CO gas. By controlling the gas flow rate of CF 4, the selectivity of Si can be controlled, because the CF 4 gas flow rate controls the CF n polymer deposition. However, we believe that, for mass production, it is better to eliminate CF n polymer deposition completely to gain higher selectivity of Si, which we achieved by increasing the carburization ratio ( SiC Si or SiC SiN ) by a gas. This improves the selectivity of Si or SiN, and a higher selectivity of photo resist can be obtained.