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 temperat ure and the addition of NF3 on the crystallinity of as-deposited polys ilicon films and on the crystalline quality of annealed films have bee n investigated with the aid of Raman spectroscopy and scanning electro n microscopy (SEM). It has been found that without the addition of NF3 it is necessary not only to have a low deposition temperature, as pre viously suggested in the literature, but also to have a high silane mo le 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 q uality annealed films obtained, at much higher deposition temperatures than is normally possible.