Study of electrical and structural properties of boron doped polysilicon films with a low nitrogen content

In this work we propose, the study of nitrogen doped Silicon films for an application as a poly-Si gate material for metal-oxide-semiconductor devices. Nitrogen doped silicon films have been deposited at amorphous phase by low-pressure chemical vapor deposition (LPCVD) from disilane Si2H6 and ammonia NH3 at low temperature (480◦C). The films with varied nitrogen contents have been boron implanted, and annealed at several annealing conditions. The influence of the annealing conditions, the nitrogen tenor and the boron dose on the electrical and the structural properties of films are investigated and correlated. Results show that the conductivity is maximal (σ ∼ 102 ( · cm)−1) for higher annealing temperature, a nitrogen content less than 2% and a strong boron dose. These results indicate that under these optimal conditions, although some nitrogen contents is present in the films, these latter have a conducting behavior. The crystallization of films was found to depend principally on the nitrogen tenor. A quasi-totally crystallization was observed for a nitrogen tenor inferior or equal to 2% and for an annealing temperature of 1100◦C during 120 min. This result is in good agreement with the greatest value of the conductivity obtained under the same conditions. C 2005 Springer Science + Business Media, Inc.