<title>Precise proximity correction for fabricating chirped diffraction gratings with direct-writing electron-beam lithography</title>

Abstract

Proximity correction is an important technique to fabricate diffractive optical elements with the direct-writing electron-beam lithography. For the precise proximity correction, the absorbed energy distribution is calculated with an electron scatter simulator based on the Monte Carlo method, and a resist profile is estimated with a resist development simulator based on the cell removal model. In this paper, we calculated the optimum electron dosage for a chirped-period diffraction grating by use of such a precise proximity correction. To reduce the calculation time, we set the cell size 200nmx200nm. The resultant resist profile, however, was much more precise than the cell size because of the interpolation. It took 24 hours to optimize the electron dosage of a grating with a width of 5mm and the minimum grating period of 4micrometers . Moreover the grating, which was fabricated according to the calculated dosage, had a profile that agreed well with the calculated profile.