the orientation of a lpcvd film in the case of a lpcvd film the orientation in the lt 100 gt direction is observed within a certain deposition temperature range when the silane pressure is set constant if the silane pressure is decreased both the upper and lower limits of the deposition temperature range within which the orientation in the lt 100 gt direction is observed are shifted toward the lower temperature region incidentally the range within which the orientation in the lt 110 gt direction is observed is also shifted and kept lower than that within which the lt 100 gt orientation is observed each of the increase in the deposition temperature and the decrease in the gas pressure serves to increase the kinetic energy of the reactive molecules adsorbed on the substrate surface the increased kinetic energy within a suitable range is considered to make it possible to achieve the orientation in the lt 100 gt direction the plasma application also serves to increase the kinetic energy in addition the plasma application produces a physical effect that weak si si bonds are removed by the sputtering effect this physical effect which is supposed to be one of the reasons for smoothing the surface of the deposited silicon film is also considered to affect the orientation of the poly si film as.