Reactive Ion Etching of SOI (SIMOX and ZMR) Silicon in Nitrogen Containing CF 4 + O 2 and SF 6 + O 2 Plasmas

Abstract

The effects of addition on the etch rate of bulk‐silicon and silicon‐on‐insulator (SOI) separation by implantation of oxygen (SIMOX) and zone melting recrystallization (ZMR) samples using and plasmas; as well as the damage assessment of the plasma are reported. In plasma, the additive reduces the etch rate of the masking oxide [chemical vapor deposited (CVD)] while significantly increasing the silicon etch rate and, thus, increasing the selectivity by 44–64%. In plasma, the silicon etch rate is increased due to the addition. However, the increase in selectivity is about 16–45%. The etch rate of SOI silicon especially in plasma is higher than that of bulk‐silicon samples. The higher etch rate of SOI samples appears related to the higher defect density of the SOI silicon. The damage assessment studied through Schottky diode and metal oxide semiconductor (MOS) capacitor samples indicates that plasma with additive introduces less damage as compared to without additive. Furthermore, postmetal annealing at 250°C for 15 min in ambient improves the characteristics of both Schottky diode and MOS capacitor devices. Thus the addition of improves the etch rate, and selectivity in some cases, and at the same time decreases the damage.