Effects of aperture size and pressure on XeF₂ etching of silicon

Abstract

 We developed a XeF₂ pulse etching system and clarified the Si etching characteristics. Dependencies of Si etching rates and etched roughness on the crystallographic orientation, number of pulses, pulse duration time, aperture size and etching pressure were measured. An etching depth and an etched roughness were 12.9 μm and 115 nm, respectively under charge pressure of 390 Pa, a pulse number of 10 and pulse duration time of 60 s. The etching depth increased by 36% with increasing the aperture width from 25 to 175 μm. This aperture size effect decreased from 36 to 20% with decreasing charge pressure from 390 to 65 Pa. The etched roughness decreases also with decreasing the etching pressure. The roughness was 25 nm under the charge pressure of 65 Pa, 50 pulses, 60 s.