Sub-grain Boundary Spacing in Directionally Crystallized Si Films Obtained via Sequential Lateral Solidification

Abstract

ABSTRACTIn this paper, we report on the average linear density of sub-grain boundaries that are found in directionally solidified microstructures obtained via sequential lateral solidification of Si thin films. Specifically, we have characterized the dependence of the sub-grain boundary density on the film thickness, incident energy density, and per-pulse translation distance. The investigation was confined to analyzing directionally solidified microstructures obtained using straight-line beamlets. It is found that the average spacing of the sub-grain boundaries depended approximately linearly on the film thickness, where it varied from 0.28m at a thickeness of 550Å to ∼0.75μm at 2,000 Å. In contrast, variations in either the energy density or the per-pulse translation distance within the investigated SLS process parameter domain were found to have a negligible effect on the spacing. Discussion is provided on a preliminary model that invokes polygonization of thermal-stress generated dislocations, and on implications of the dependence of device performance on the film thickness.