Suitable SiNx films for constructing attenuated phase-shifting masks (APSMs) to be operated in the deep ultraviolet (DUV) regime are obtained by varying the gas flow ratios in a plasma enhanced chemical vapor deposition process. Characteristics of the films such as optical constants, optical band gaps, material compositions, irradiation stability, etching selectivity, and adhesion strength are experimentally analyzed in detail. Subquarter micron patterns on SiNx films are obtained by utilizing DUV lithography and silylation technique for the proof of feasibility. These results indicate that the SiNx films thus fabricated can meet all the requirements for building such APSMs working at wavelengths of 248 and 193 nm.