Fabrication of submicron three-dimensional structure by plane-pattern to the cross-section transfer method using synchrotron radiation lithography

摘要

In this paper, influences of Fresnel diffraction for the advance accuracy in sub-micron resolution of the PCT (Plane-pattern to Cross-section Transfer) technique are discussed. Some analytical simulations were performed for a prediction of X-ray intensity distribution. The X-ray mask pattern employed in this work was a set of right triangles placed in double rows facing each other which was designed by the fact that when mask slit becomes narrower while approaching the corner, the influence of the diffraction gradually becomes more significant. In X-ray lithography, especially for optical applications, it has been realized that the Fresnel diffraction is most effective factor for designing me shape of slits in submicron. The group of triangle mask patterns has 1.48 μm-pitch and 20 μm-height with 0.5 μm-thick Ta absorber. The submicron structure was successfully fabricated by PCT with a proximity gap of 300 μm. The fabricated structure exposed by 1.84kJ/cm~3 X-ray dose has 190 nm in height. The analysis was summarized by comparing the PCT simulations and the data from experimental results.