STUDIES OF THE EFFECTS OF NF3 ON THE GROWTH OF POLYSILICON FILMS BY LOW-PRESSURE CVD .2. EFFECT ON CRYSTALLINITY

In this paper the effects of silane mole fraction, deposition temperature and the addition of NF3 on the crystallinity of as-deposited polysilicon films and on the crystalline quality of annealed films have been investigated with the aid of Raman spectroscopy and scanning electron microscopy (SEM). It has been found that without the addition of NF3 it is necessary not only to have a low deposition temperature, as previously suggested in the literature, but also to have a high silane mole fraction in order to obtain amorphous films from which high-quality material can be obtained upon annealing. With the addition of NF3 it is has been found that amorphous layers may be grown, and hence good quality annealed films obtained, at much higher deposition temperatures than is normally possible.