Study of TiSi-nitride based attenuated phase shift mask for ArF lithography

ArF DUV (lambda=193 nm) lithography is rapidly emerging after 248 nm lithography because of the demand for further resolution improvement and wider Depth Of Focus(DOF). However, the 193nm lithography requires innovative development in various areas, such as laser sources, resist chemistry, new PSM shifter materials, and optics materials. In this study, we evaluated TiSi-nitride based new attenuated PSM in terms of mask making process and its lithographic performance for ArF lithography. We used two kinds of TiSi-nitride based attenuated PSM blanks having 6% and 9% transmittance, respectively. Chemical durability of TiN/SiN film was evaluated. We selected optimal dry etching condition for mask making with good mask profile(side wall angle greater than or equal to 85 degrees) and Quartz(Qz) substrate roughness. The DOF margin at 9%-PSM was lager than those of others(6%-PSM and BIM) and Exposure Latitude(EL) of PSM was larger than that of BIM. Therefore, we concluded that TiSiN-based attenuated PSM was effective for ArF lithography.