X-ray diffraction, transmission and scanning electron microscopy, and secondary-ion mass spectrometry data demonstrate that the grain size, structure, and composition of polycrystalline silicon (poly-Si) films grown using hydride pyrolysis depend on the GeH 4 : SiH 4 volume ratio in the gas mixture, dopant (boron or phosphorus) concentration, substrate temperature, and heat-treatment temperature. The films grown at substrate temperatures below 600 ° C are amorphous, and those deposited at 600 ° C are amorphous-crystalline. Textured poly-Si films are only obtained at 620 ° C or higher substrate temperatures. Doping with germanium, an isovalent impurity, improves the structural perfection of poly-Si films.

The dependence of the resistivity of doped polysilicon films on fabrication conditions is studied experimentally. The films are produced from a silane-germane-diborane or a silane-germane-phosphine gas mixture, being doped with germanium in combination with boron or phosphorus, respectively. The process parameters are identified that strongly influence the resistivity and temperature coefficient of resistance of the resulting films. They are (i) the volume ratio of germane to silane, (ii) the volume ratio of silane and germane to diborane and phosphine, (iii) substrate temperature, and (iv) annealing temperature. Common and distinctive features are identified in the patterns of behavior of resistivity observed in undoped and variously doped films. It is shown that film resistivity is to a large extent determined by grain size. It is also found that increasing the temperature of deposition or annealing makes for lower film resistivity. THIN FILMS

No abstract

No abstract

No abstract