Subpixel pattern edge placement controllability of digital scanner

The Digital Scanner (DS) being developed by Nikon is an optical maskless exposure tool with DUV light source and a micromirror-type spatial light modulator (SLM). The SLM forms a pixelated image; although each micromirror operates in a binary mode, the DS is capable to control pattern edges with subpixel resolution. This is because the pixel size on the wafer plane is smaller than the optical resolution, and therefore multiple pixels can contribute to each point in a projected image. We report simulation results of subpixel edge placement controllability of the DS. Actual exposure results on our experimental tool are also presented.