Pressure dependence of the growth of polycrystalline silicon by low-pressure chemical-vapor deposition

Abstract

The growth of polycrystallinesilicon at temperatures below 640 °C by the pyrolysis of silane at very low pressures (<40 mTorr) was found to be activated with an activation energy depending on the pressure. Two modes of growth were observed: columnar and twinned, below and above 10 mTorr, respectively. The rate of growth for both types is only slightly dependent on the pressure. The columnar growth is associated with an increase of the activation energy, while the change to the twinned structure is associated with a drop in the activation energy to almost zero from where it increases with pressure. The influence of the flow mode is also discussed.