Influence of shadowing effect on morphology and microstructure of silicon thin film in chemical vapor deposition

Abstract

Influences of gas incident angle () on surface morphology and microstructure of hydrogenated amorphous silicon (a-Si:H) thin films are investigated, which were grown using an oblique angle hot wire chemical vapor deposition (OAD-HWCVD) technique. An exponential relationship between the tan and RMS roughness is observed. The film surface morphology transforms from a self-affine surface into a mounded surface when the incident angle is larger than a critical angle c(60 c 75). Influences of on the microstructural properties of silicon thin films are characterized using Raman scattering and FT-IR measurements. As c, owing to the qusai-local shadowing effect, increasing increases the quantity and size of micro-voids, leading to the decrease of film density and quality. For c, the nonlocal shadowing effect causes the formation of large voids or cracks and the proportion of multi-hydride (SiHn, n 2) increases. Combined with the scaling theory, the relationship between the shadowing effect and the surface morphologies and microstructures of amorphous silicon thin films is discussed.