GISAXS and ATR-FTIR Studies on Stress-Induced Microstructure Evolution of a-Si:H under H₂ Plasma Exposure

Microstructure evolution in the surface layer of hydrogenated amorphous silicon (a-Si:H) film exposed to H₂ plasma is investigated using grazing-incidence small-angle x-ray scattering and attenuated total reflection-Fourier transform infrared spectroscopy. Molecular hydrogen generated in the microvoids through H-abstraction reaction drives the evolution of the void shape from spherical to ellipsoidal as well as increases the average void volume and total void volume fraction. High-pressure H₂ in the microvoid promotes the formation of a strained structure with high compressive stress within the a-Si:H film, which favours the generation of the SiH_n complex in the subsurface layer of the a-Si:H film by H insertion into strained Si–Si bonds.