Characteristics of Grain Boundaries in Polycrystalline Si Films fabricated by Chemical Vapor Deposition and Subsequent Annealing

Abstract

Polycrystalline Si films are a promising structural material for microsensing devices. On its application, mechanical fatigue phenomena may be worrying in view of long-term reliability. For revealing its mechanism, it is necessary to understand the structural behavior of its correlative grain boundaries (GBs). In the present study, using a conventional admittance spectroscopic technique, we have systematically clarified the formation process and the thermally induced behavior of interface states at GBs in chemical vapor deposited amorphous Si films after thermal annealing. As an unique trial, we have also investigated the correlation between the GBs states and the mechanical properties using polycrystalline Si membranes fabricated. The results indicate that a deeper energy shift of the GBs states is caused by adding an external stress and that its quantity depends on Young's modulus of the films. We expect that our findings contribute to the solution of fatigue problems of polycrystalline Si films in the near future. Keywords : polycrystalline Si films, crystallization, grain boundary, GBs states, stress, Young's modulus. © 2004, The Institute of Electrical Engineers of Japan. All rights reserved.