Defect printability analysis in electron-beam cell projection lithography

Abstract

In electron-beam (EB) cell projection lithography, the defect in resist pattern caused from the defect on aperture mask (EB mask) must be diminished. We have experimentally evaluated the printability of the defect and confirmed EB mask inspection standard. Line-and-space (L&S) patterns of 0.20 μm width (on the wafer substrate) have been fabricated on the EB mask, which has bridge defects with width of 0.20 μm and height of 0.04-0.20 μm in the line patterns, and exposed with changing the exposure dose. The programmed bridge defect of 0.04 μm height on the wafer (1.0 μm on the EB mask) is not printable at the optimum exposure dose. However, at 90% of the optimum exposure dose, it forms a 0.08 μm disconnection defect. The defect on the EB mask is printable especially in lower exposure dose range. The defect printability is higher than the resolution of L&S pattern. The defect larger than 10 % of line pattern width on the EB mask are not allowed in order to form high quality resist patterns.