OXYGEN ADDITION EFFECTS IN SYNCHROTRON RADIATION EXCITED ETCHING USING SF6

The effects of oxygen addition on the synchrotron radiation-excited etching of crystal Si, poly-Si, and SiO2 using SF6 reaction gas are investigated. Without oxygen, two phenomenologically classified reaction mechanisms are observed: gas phase and surface excitation mechanisms. With oxygen addition, the gas phase excitation mechanism disappears and only the surface excitation mechanism becomes dominant. Oxygen addition is extremely effective in the microfabrication of SiO2 line and space patterns using poly-Si as an etching mask. Its addition creates high selectivity between SiO2 and crystal Si. Furthermore, it is considered that the added oxygen removes some etching suppressing species generated on the poly-Si surface.