Silicon nitride films are widely used in micro-bolometer focal plane arrays as supporting layer and insulation layer. In this paper, silicon-rich hydrogenated amorphous silicon nitrides (α-SiNxH，0.80≤x≤1.16) were prepared by radio-frequency plasma-enhanced vapor deposition. The film microstructures were analyzed using X-ray photoelectron spectroscopy (XPS) and Fourier transimission infrared spectroscopy (FTIR). Results reveal that α-SiNxH contain the basic structural units of Si3N4. Moreover, the Si-N stretching modes located at 790, 820 and 950 cm-1, are ascribed to Si3-Si-N, N2-Si-H2, and H-Si-N3 configurations, respectively. The residual stresses were measured by curvature measurement, indicating that the residual stress in the film generally exhibits tension, but this tensile stress gradually decreases while the SiH4 flow rate increases. The theoretical analysis shows that the H-Si-N3 configuration is helpful for developing tensile stress, while the Si3-Si-N and Si-Si configurations are helpful for compressive stress. Therefore, by optimizing the processing conditions, α-SiNxH, with suitable microstructures can be prepared, by which the film stress can be better controlled.