INVESTIGATION OF HYDROGEN PLASMA ETCHED SI SURFACES

Roughness of Si surfaces irradiated with a hydrogen electron cyclotron resonance plasma at several substrate temperatures was investigated using scanning electron microscopy and reflection high-energy electron diffraction (RHEED). When the substrate temperature is below 100-degrees-C, the surface remains smooth after irradiation for 10 min. However, at the higher temperatures, conelike projections are formed on the surface. By RHEED analysis, the facet orientation of the projections changes from (511) to (211) with growth of the roughness. These facet surfaces are composed of microsteps with {111} risers. The temperature dependence of the Si etch rate was also measured, so that the etch rate decreased with increase of the substrate temperature. IR spectroscopy and elastic recoil detection analysis were used to identify hydrogen penetration into the Si bulk. The temperature dependence of both the etch rate and the roughness formation will be discussed on the basis of the reduction of hydrogen atoms contributing to the etch reaction.