Self-Limited Etching of Silicon Nitride Using Cyclic Process with CH2F2 Chemistry

In this paper, we used the alternating cycle of adsorption and desorption processes to carry out self-limited etching of silicon nitride, and explored the use of different hydrofluorocarbon (HFC) gases in the adsorption process in order to present self-limiting characteristics. Two gases as CHF
3
and CH
2
F
2
are selected to conduct two sets of experiments respectively. The results show that CHF
3
produces etching effect on SiN, without deposition effect, and no self-limiting characteristics are presented. In contrast, the etching rate of SiN firstly increases and then decreases with the increase of CH
2
F
2
step time. It is suitable for precise etching thickness control by the cycle number.