Characteristics of silicon nitride reaction to vapor-phase HF gas treatment

Abstract

Evidence has been presented that the mixed anhydrous hydrogen fluoride (HF) and methanol (CH3OH) gas, which is used for dry etching the sacrificial layer of silicon dioxide film, deteriorates silicon nitride film (SiN). From the results of chemical composition analyses, the alteration product was identified to be ammonium hexafluorosilicate ((NH4) 2SiF6). We found that the alteration product can be decomposed and removed by heat-treatment in atmosphere. The deterioration of the SiN by the HF/CH3OH gas treatment is approximately 3 nm/min, and the growth rate of the SiN alteration product is approximately 30 nm/min.