An efficient algorithm for stencil planning and optimization in E-beam lithography

Character projection is a promising technique to dramatically improve throughput of E-beam lithography. However, its effectiveness depends on how good the stencils are planned and optimized. Recently Kuang and Young proposed an efficient heuristic based on 2-D bin-packing for the stencil optimization. In this paper, we identified drawbacks in their approaches, and developed a better algorithm that reduces the shot numbers to less than half of theirs in average. The key point is introducing the merit frequency/area (f/A) to select candidate characters and proposing an accurate and efficient algorithm to estimate the occupied area of characters before placement. Experimental results verify the effectiveness of the proposed method.