High selectivity (SiN/SiO2) etching using an organic solution containing anhydrous HF

An etching process with high selectivity for SiN relative to SiO2 at a low temperature is required for an etching process in LSI process. We achieved SiN film etching with high selectivity using an organic solvent (ethylene glycol dimethyl ether) containing anhydrous hydrogen fluoride. Selectivity as high as 15 was obtained at 80 °C. It was found that anhydrous HF effectively induces high selectivity for SiN relative to SiO2. SiN film etching with high selectivity performed at low temperature for a single wafer process can be readily applied to future node technology devices.