Etching of Silicon and Silicon Dioxide in Dense Low-Pressure Inductively Coupled Radiofrequency Discharge Fluorocarbon Plasmas

The results of a study on the selective etching of SiO₂ and Si in dense low-pressure (p < 1 Pa) inductively coupled radio-frequency discharge fluorocarbon (HF₃ and HF₃ + H₂) plasmas in a nonuniform magnetic field are reported. It was found that the selectivity of etching SiO₂/Si increased from 9 to 24 with the addition of hydrogen. In the etching of SiO₂ in a HF₃ + H₂ plasma under certain process conditions, groove ridges were formed at the bottom of the etched groove. The mechanisms of ridge formation and the role of ion bombardment in this process are discussed.