Etching characteristics of NF3 and F3NO at reactive ion etching plasma for silicon oxide and silicon nitride

Reactive ion etching of silicon oxide and silicon nitride was conducted by the injection of nitrogen trifluoride (NF 3 ) and nitrogen oxide trifluoride gas (F 3 NO). The etching process was studied using a residual gas analyzer (RGA) and optical emission spectroscopy (OES); this included confirming and comparing the characteristics of the F 3 NO plasma to that of the NF 3 plasma by discharging and measuring the pure NF 3 plasma and F 3 NO plasma. Furthermore, silicon oxide and silicon nitride etching were performed using a process gas (NF 3 , F 3 NO) and an argon mixture. The plasma etching process was similarly diagnosed by RGA and OES, and the etch rate was calculated by measuring the reflection. The etch rate of silicon oxide during F 3 NO/Ar plasma etching is approximately 94% of that for NF 3 /Ar plasma etching and the etch rate of silicon nitride is approximately 76% of that for NF 3 /Ar plasma etching under the same conditions. The RGA and OES measurements confirmed that more O + , NO + , and O 2 + ions were generated in the F 3 NO plasma than in the NF 3 plasma. This difference makes it possible to confirm the variation in etch rates between silicon oxide and silicon nitride.