Introduction

Methyl Fluoride (CH3F) , also known as Fluoromethane, Freon 41, Halocarbon-41 and HFC-41, is a non-toxic, liquefied and flammable gas at standard temperature and pressure. It is an environmentally friendly dry etching gas with low GWP, which shows very high performance in plasma etching of silicon compound films in semiconductor manufacturing. Etching of the Si3N4 spacer can be achieved in CH3F-O2-He mixtures, which offer a high selectivity towards silicon. CH3F/C4F8 Ratio will have effect on the Oxide-to-Nitride Selectivity in a Self-Aligned-Contact etching process. CH3F is also expected to outpace capacity as 3D NAND flash start-ups.

Applicant and Patent