Ultraviolet excited Cl-radical etching of Si through native oxides

Analysis of the etching of Si by ultraviolet irradiation-excited Cl radicals through native oxide diffusion on Si surfaces at 200 degrees Celsius shows that surface morphologies and Si etch rate depend on the native oxides that develop due to wet chemical treatments prior to etching. Scanning electron microscopy reveals caves on the etched Si surface, confirming that the occurrence of etching does not affect the native oxide layer as it is supported by a thermally grown thick-oxide etching mask.