Effects of backsputtering and amorphous silicon capping layer on the formation of TiSi2 in sputtered Ti films on (001)Si by rapid thermal annealing

Abstract

The effects of backsputtering and amorphous silicon capping layer on the formation of TiSi2 in sputtered Ti films on (001)Si by rapid thermal annealing have been studied by scanning and transmission electron microscopy as well as Auger electron spectroscopy. Backsputtering cleaning of the silicon substrates was found to be effective in alleviating the island formation and in promoting the epitaxial growth. Auger depth profiles indicated that intermixing of Ti and Si occurred in samples with substrates cleaned by in situ backsputtering prior to depositions. High-resolution lattice images of cross-sectional samples revealed the presence of continuous amorphous layers between polycrystalline Ti grains and single-crystal Si substrates in the backsputtering-cleaned samples. An amorphous silicon capping layer was found to degrade the surface morphology and hinder the formation of silicide epitaxy. The formation and growth of epitaxial regions are more difficult in samples with amorphous silicon capping layer since an additional step is required for the polycrystalline grains in the upper layer to realign with the underlying epitaxial TiSi2 layer to form an epitaxial region. Better surface morphology is correlated with improved silicide epitaxy with its more favorable energetics.