Topographical and structural investigations of phosphorous-doped silicon films

The influence of two different ex situ doping processes, diffusion doping and ion implantation, on the structure and surface topography of low-pressure chemical vapour deposited silicon films has been studied using atomic force microscopy. The films were grown at temperatures between 550 degrees C and 630 degrees C. We have found that roughness values depend strongly on deposition temperature and are obviously larger for diffusion doped films. For comparable annealing parameters the structures of the films are mainly determined by the deposition temperature. Layers grown below 570 degrees C show unusual grain shapes. This irregular structure in connection with the low dopant concentration can be seen as the reason for the non-reproducible resistance of high-resistivity layers.