Ultraviolet (UV)-transparent silicon nitride films were deposited in a plasma enhanced chemical vapor deposition reactor. The dependence of the film properties on process parameters has been studied. UV transmittance, refractive index, hydrogen content, and step coverage were compared to UV-opaque films. A significant difference in film growth between UV-opaque and UV-transparent SiNx layers has been detected. When him properties shift to an increased UV transparency, step coverage worsens significantly. This phenomenon is suggested to be caused by a strong reduction to Si-Si bonds fur films below stoichiometric composition at low SiH4/NH3 gas flow ratios.