Polycrystalline silicon, a molecular dynamics study: II. Grains, grain boundaries and their structure

Abstract

Polycrystalline silicon (poly-Si) is an excellent material for use in microelectronic devices, both in electrical and mechanical applications. Its mechanical and electrical properties are widely adjustable, its processing technology is compatible with existing microcircuit manufacturing technology, and its availability and recyclability are at a high level. Here, we focus on investigating the properties of poly-Si that distinguish it from other forms of silicon, that is, grains, grain boundaries, and the conditions and treatments that determine grain and grain boundary properties. Starting from the molecular dynamics simulations of the deposition of thin poly-Si films under different growth conditions we study the properties of the films, grains, and grain boundaries as a function of growth time, growth temperature, and post-annealing. We aim to get data and information that will form the essential basis for future research on the electrical properties of poly-Si. The main results are: (i) the effect of post-annealing on the distribution of the grain size and grain boundary thickness (ii) the distribution of the grain orientations, and (iii) the density of the 3- and 5-bonded atoms as a function of deposition temperature.