Low resistance polycrystalline silicon by boron or arsenic implantation and thermal crystallization of amorphously deposited films

Polycrystalline silicon films with high surface smoothness, good step coverage, and a relatively large grain size of ∼0.3 μm have been prepared by low-pressure chemical vapor deposition in the amorphous state and subsequent crystallization in a furnace. The final grain size achieved does not significantly depend on the initial annealing temperature used to crystallize the layer. For heavily boron implanted films, a clear correlation between sheet resistance and average grain size is found and the resistivity is close to the single crystal value for the amorphously deposited films. In contrast, only a minor resistivity reduction relative to standard polycrystalline silicon could be achieved by amorphous deposition for arsenic implanted films.