Structure and grain boundary defects of glow-discharge polycrystalline silicon films deposited using disilane

Abstract

Undoped polycrystalline Si (poly-Si) films were deposited as a function of the rf power (0–30 W) and deposition temperature Td (600–750 °C) using disilane by a plasma-enhanced chemical vapor deposition (PECVD) method. For comparison, poly-Si films were also deposited using monosilane. The preferential orientation to a random, (100), or (110) texture was able to be selected by changing some of these deposition conditions. It was suggested that the change in the texture is caused by a change in the surface-diffusion coefficient of SiHn adsorbates and by effects of an ion bombardment, rather than by a change in the deposition rate. For PECVD poly-Si films, both the x-ray relative intensity and the crystallinity rapidly decreased with decreasing the film thickness thinner than 0.4 μm. The value of g in the electron spin resonance spectra and that of stress strongly depended on the rf power and the thickness. Further, when a film was annealed in H2 plasma, the value of g shifted from 2.0054 to 2.0043. These results are examined in terms of formation of different types of grain boundary which can be associated with a lattice deformation around the dangling bonds.