Abstract: HSG with an uneven surface is formed by (i) removing a spontaneous oxidation layer formed on an amorphous silicon surface of a semiconductor substrate by preprocessing, (ii) dissociating hydrogen in dangling bonds by heating it to a processing temperature, (iii) forming an amorphous silicon/polysilicon mixed-phase thin film selectively on solely an activated surface of the amorphous silicon surface in a silicon compound atmosphere, and (iv) annealing the film continuously. This method is characterized in including (a) a process which supplies a phosphorus compound and a dilution gas into a reactor while the semiconductor substrate is heated to a processing temperature, and (b) a process of annealing the semiconductor substrate in an atmosphere which contains the phosphorus compound and the dilution gas.

Abstract: A rough surface made of polysilicon grains is formed on an amorphous silicon film disposed on a semiconductor substrate by the steps of: (i) forming an amorphous silicon-polysilicon mixed-phase layer having a first density on an activated surface of the amorphous silicon film by contacting the surface with a gas containing monosilane at a first flow rate of monosilane and at a first temperature; and (ii) annealing the amorphous silicon-polysilicon mixed-phase layer to form polysilicon grains therefrom, thereby forming a rough surface made of polysilicon grains. In the above, the improvement includes using disilane in place of monosilane at a second flow rate lower than the first flow rate and at a second temperature lower than the first temperature to form an amorphous silicon-polysilicon mixed-phase layer having a second density higher than the first density. Another improvement includes saturating the reactor with hydrogen gas during the heating step.

Abstract: A rough surface made of a doped polycrystal silicon film is formed on an amorphous silicon film disposed on a semiconductor substrate, by a method including the steps of: (a) activating dangling bonds present on a surface of an amorphous silicon film; (b) forming an amorphous silicon-polysilicon mixed-phase layer on the surface of the amorphous silicon film by contacting the dangling bonds with a gas containing silane gas and dopant gas while controlling the ratio of dopant gas to silane gas to bind silicon atoms and dopant atoms to the dangling bonds; and (c) annealing the amorphous silicon-polysilicon mixed-phase layer to form polysilicon grains therefrom, thereby forming a rough surface made of doped polysilicon film. Doping can be conducted after formation of the polysilicon grains.