Influence of the Shape of the Illumination Aperture on the Intrafield Image Displacement

概要

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At the state-of-the-art lithographic processes, the efforts such as large diameter lens with high numerical aperture and modified illumination to satisfy the need for increased resolution and depth of focus simultaneously deteriorate the distortion characteristics. In this paper, we studied the intrafield image displacement with the various illumination apertures (conventional, quadrupole, annular), and estimated its influence on the actual overlay accuracy quantitatively. It was found that deviation of the distortion components of modified illumination apertures from conventional aperture (NA 0.57, σ 0.6) brought about the overlay between conventional and modified illumination-exposed layers within ±15nm in the full-field (22×22mm^2). In the practical reason, we suggest the scheme with the magnification correction for the exposure step, which has its basis on the telecentricity characteristics for each apertures.
社団法人電子情報通信学会の論文
1995-07-27