The effect of deposition process parameters and post-deposition treatments on the poly- and amorphous-silicon morphology

Abstract

The surface roughness and topography of low-pressure chemical vapor deposited (LPCVD) silicon films have been investigated by atomic force microscopy (AFM) in the non-contact mode. Deposition parameters were varied and various post-deposition treatments tested. The morphology of poly-silicon and amorphous-silicon were compared as well as morphology modification due to different amorphous-silicon deposition temperatures. The effects of post-deposition treatments: ion implantation and oxidation have been investigated. A significant difference in morphology between poly-silicon and amorphous-silicon films was revealed. Poly-silicon roughness was an order of magnitude higher than amorphous-silicon roughness. The surface morphology of amorphous-silicon layers was strongly affected by the deposition temperature. Asperity concentration and height were highly sensitive to the deposition temperature in the range of 545–560 °C. Phosphorous, argon and arsenic ion implantation decreased the roughness of amorphous-silicon films. On the other hand, the oxidation process caused an increase of roughness. Moreover, implantation followed by oxidation resulted in a drastic increase of the surface roughness, with a pronounced dose dependence.