Features of the Morphology and Structure of Thin Silicon Films

Abstract

Abstract—The surface morphology and structure of LPCVD silicon thin films (with thicknesses of 40 nm or less) obtained at a deposition temperature of T = 550°С, at which amorphous films (a-Si) are usually obtained, and at a deposition temperature of 584°С, at which films of polycrystalline silicon with hemispherical grains (HSG-Si) with a large surface roughness are obtained, are studied. It is found that, at a deposition temperature of 550°С, amorphous films with comparatively smooth surfaces form in the case of thicknesses of 35 nm or more, and granular polycrystalline HSG-Si films with a large surface roughness form in the case of thicknesses of 35 nm or less. It is shown that granular silicon films deposited at T = 550°С (d = 28 nm) have a morphology that is analogous to that of HSG-Si films deposited at T = 584°С (d = 29 nm). It is found that, as the thickness of the deposited Si film decreases to 28 nm, the lower boundary of the temperature range at which HSG-Si films form is shifted toward smaller temperatures to T = 550°C.