Proceedings PaperWavefront engineering from 500- to 100-nm CD
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'Wavefront engineering' is the discipline of producing an exposure pattern, adequate for delineating resist at high yield, in spite of the limitations of the imaging technology. Although this discipline relies on century-old optical insights and despite decade-past experiments demonstrating dramatic improvements in resolution and process-window, this field has languished in comparison to traditional approaches, such as exposing with shorter wavelength radiation or larger numerical apertures. Further progress in NA and lambda will soon be limited by physical and materials considerations, necessitating other schemes for decreasing the critical dimensions (CDs) of volume-production devices. Today, with 193 nm systems delayed and non-optical approaches confronting infrastructure and economic barriers, the semiconductor industry is trying to adopt such wavefront engineering techniques as off-axis illumination (OAI), optical proximity correction (OPC) and phase-shifting masks (PSMs). CD/CAM methods similar to those applied to optimize lenses and chips now are being applied to optimize the exposure-dose pattern itself.