Model of morphology evolution in the growth of polycrystalline beta-SiC films

The growth of beta-SiC films via chemical vapor deposition (CVD) has been u nder intensive investigation because this is viewed to be an enabling mater ial for a variety of new semiconductor devices in areas where silicon canno t effectively compete. However, the difficulty in achieving single-crystal or highly textured surface morphology in films with low bulk defect density has limited the use of beta-SiC films in electronic devices. Although seve ral researchers have reported results relating the morphology of beta-SiC f ilms to deposition parameters, including substrate temperature and gas comp osition, detailed knowledge of the effects of deposition parameters on film morphology and crystallographic texture is still lacking. If these relatio nships between deposition parameters and film morphology can be quantified, then it may be possible to obtain optimal beta-SiC film morphologies via C VD for specific applications such as high-power electronic devices. The purpose of this study is to predict the dependence of the surface morph ology of beta-SiC films grown by CVD on substrate temperature and inlet ato m ratio of Si:C, and to model the morphological evolution of the growing po lycrystalline film. The Si:C ratio is determined by the composition of the reactant gases, propane (C3H8) and silane (SiH4). A two-dimensional numeric al model based on growth rate parameters has been developed to predict the evolution of the surface morphology. The model calculates the texture, surf ace roughness, and grain size of continuous polycrystalline beta-SiC films resulting from growth competition between nucleated seed crystals of known orientation. Crystals with the fastest growth direction perpendicular to th e substrate surface are allowed to overgrow all other crystal orientations. When a continuous polycrystalline film is formed, the facet orientations o f crystals are represented on the surface. In the model, the growth paramet er alpha(2D), the ratio of the growth rates of the {10} and {11} faces, det ermines the crystal shapes and, thus, the facet orientations of crystals. T he growth rate parameter alpha(2D) used in the model has been derived empir ically from the textures of continuous beta-SiC films reported in the liter ature. (C) 2000 Elsevier Science S.A. All rights reserved.