Optimization of Optical Parameters in KrF Excimer Laser Lithography for Quarter-Micron Lines Pattern (Special Issue on Quarter Micron Si Device and Process Technologies)

概要

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Optical parameters of KrF excimer laser stepper are optimized for 0.25 μm level patterning by means of a light intensity simulation method. The light intensity simulation method is applied in conventional and two modified illuminations (annular and 4-point) to improve the depth of focus (DOF) at 0.25 μm periodic lines and spaces pattern (L&S). Simulation results obtained are; (1) the DOF of conventional illumination is not sufficient even in the optimum condition (NA=0.5, σ=0.8), (2) more than 1.5 μm DOF could be achieved with an annular illumination, if present resist performance is improved slightly, and (3) wider DOF is obtained in the case of with 4-point illumination. However, the DOF is rather degraded in the specific sized (near double/triple sized) region and oblique pattern, therefore the application of this illumination is restricted into some specific mask layout pattern.
社団法人電子情報通信学会の論文
1994-03-25