Effects of argon and hydrogen plasmas on the surface of silicon

We investigated the effects of argon and hydrogen plasmas on the structure and electrical properties of the surface of silicon wafers. Surface roughness and defect density were measured by atomic force microscopy and photothermal deflection spectroscopy, respectively. The electronic properties of the silicon surfaces were evaluated by forming a Schottky contact on the plasma-treated surfaces. A significant surface roughness was observed on hydrogen-plasma-treated surfaces whereas the roughness on argon-plasma-treated samples was much smaller. Whereas the surface defect density was larger after argon plasma than after hydrogen-plasma treatment. Submitting an argon-plasma-treated surface to a subsequent hydrogen plasma reduced the density of defects created by the first treatment. The ideality factors of the Schottky barrier diodes were qualitatively consistent with the surface defect density. The hydrogen plasma reacts with the silicon surface and introduces surface roughness by breaking Si-Si bonds. The hydrogen atoms bond to the surface defects and consequently reduce the defect density. In contrast, the argon plasma sputters the silicon surface uniformly and hence creates defects. (C) 2002 Elsevier Science Ltd. All rights reserved.