Dry Etch Process in Magnetic Neutral Loop Discharge Plasma

Abstract

Magnetic neutral loop discharge (NLD) plasma, which has attractive characteristics in terms of plasma production and spatial controllability, was successfully applied to a high-rate etch process with satisfactory uniformity. In the application to the SiO2 etch process, an etch rate of about 1 µm/min was obtained with C4F8 gas pressure of 0.4 Pa, and the uniformity was better than 3% for the 6-inch wafer. A highly selective process was achieved by mixing C4F8 with H2. At a gas flow ratio of H2/(H2+C4F8)×100=65%, the obtained selectivity of SiO2/Si was higher than 100 and the etch rate of SiO2 was sustained on the order of 800 nm/min, where 13.6 MHz rf power was supplied in the continuous wave (CW) mode.