Synchrotron radiation - assisted etching of SiO2 and polycrystalline silicon surfaces

Synchrotron radiation (SR)-assisted etching of SiO2 and polycrystalline silicon surfaces is studied using SR from UVSOR facility at IMS as an extreme ultraviolet light source and SF6 and Cl2 as etchants. The etch rates were measured as a function of parameters, such as etchant pressure, bias voltage and also the wavelength of the irradiated light. In particular, the pressure dependence of the etch rate obtained using undulator light at 25.1 and 14.2nm, enables us to unambiguously conclude that the etching of SiO2 by SF6 is greatly enhanced by photo-excitation of the surface adsorbate. The mechanisms of etching reactions are discussed in terms of the results obtained by Urisu et al. of NTT and the authors