High-resolution electron microscopy of diamond hexagonal silicon in low pressure chemical vapor deposited polycrystalline silicon

摘要: Thin poly-Si layers deposited at 625 °C by LPCVD that are used in silicon technology for microelectronics exhibit a pronounced additional x-ray diffraction peak about 0.334 nm. High-resolution electron microscopy (HREM) reveals this stems from {01 0} reflections of diamond hexagonal (dh) Si phase, which occurs as small inclusions with the orientation relationship (0 1) ‖ (0001), [011] [2 0] to cubic (dc) matrix. Due high density planar faults on {111}, dh-Si phase also exists form 2H polytype ( 1 ) 0]. In first case formation may be understood multiple twinning transformation process, and second glide Shockley partial dislocations {111} planes. Various other polytypes occur, have all common make major contribution nm peak. The medium temperature layer deposition leads 〈011〉 preferential twins well compressive stress itself. This seems promote dh-Si. strong behavior produces typical tilt grain boundary between adjacent grains: 0], 16), Θ = 35°with translation vector t 1/2[03 1] parallel it. vanishes film after annealing temperatures above 1000 due growth recrystallization.