Silicon surface cleaning using XeF 2 gas treatment

Abstract

XeF 2 gas treatment has been studied with the aim of finding a new method of silicon surface cleaning. The clean silicon surface is usually obtained by growing a thin oxidized layer on the substrate surface. Then this layer is evaporated by in-situ annealing in ultra-high vacuum (UHV) conditions. In this work, instead of forming a thin oxidized layer, we produced SiF x ( x = 1, 2, 3) terminations on the silicon surface treating the surface with XeF 2 gas. The treatment in XeF 2 vapors cleaned the Si surface from hydro-carbon contaminations so that silicon carbide is not formed on the surface during annealing. The SiF x terminations were completely removed by annealing the Si sample at a temperature higher than 723 K in UHV conditions. After annealing we did not observe any polluting atoms on the surface. Although the clean silicon surface was obtained at a temperature of about 723 K, a high structural perfection of the surface was observed only after additional annealing at 1023 K. This method of silicon surface cleaning, using treatment in XeF 2 gas, may be used in molecular beam epitaxy.