Influence of carbon monoxide gas on silicon dioxide dry etching

Abstract For narrow gap reactive ion etching (RIE) of SiO2 using CF4, CHF3 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 CF4, the selectivity of Si can be controlled, because the CF4 gas flow rate controls the CFn polymer deposition. However, we believe that, for mass production, it is better to eliminate CFn 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.