抄録
Si, Ga As and Al surfaces exposed to etching gases under Ar F excimer-laser (193nm) irradiation have been studied by in situ x-ray photoelectron spectroscopy (XPS). The kinetics of photochemical etching and the resulting products on the solid surfaces have been revealed from the chemical shifts of adsorbates and substrate atoms. The etch products are shown to be Si Fx (x=∼4) units and molecular fluorine in Si etching in NF3, GaCl3 and AsCl3 in Ga As etching in HCl, and Al Clx (x=2, 3) in an Al/BCl3 system. The valence band spectra of etched Si surface indicate a systematic shift of the band edge to form a surface depletion layers, which is caused by the photogenerated majority carriers trapped in the semiinsulating fluorosilyl surface layer. By controlling the surface chemistry, pattern projection etching and CVD have been achieved.
