The role of mask technology is going through a major change as silicon technology moves into the sub 0.5 micrometers regime and optical lithography continues to be the predominant approach. Several possible options are being considered such as DUV, PSM, oblique illumination, optical proximity correction, or some combination of these methods. In addition to tighter mask requirements, a significant challenge by itself, there are unique mask technology development issues to support each lithography option. Practically speaking, masks for the sub 0.50 micrometers lithography regime are becoming less commodity products and more an integral part of the front end silicon technology development. Mask technology is foreseen to have an increasingly important role in the 0.35 micrometers and 0.25 micrometers technology generations and beyond. In this paper, we will first describe the role of mask technology in the sub 0.5 micrometers lithography regime by examining the technology roadmap, specification requirements, and the mask impact on lithographic performance. Secondly, we will describe the major technical challenges facing mask technology and fabrication. Examples will be given. Lastly, we will suggest how to meet these challenges to satisfy the needs of silicon technology.