Proximity Correction for Fabricating a Chirped Diffraction Grating by Direct-Writing Electron-Beam Lithography

This paper describes a proximity correction for fabricating a chirped diffraction grating by direct-writing electron-beam lithography. The electron dose distribution is optimized by calculation with an electron-scatter simulator and a resist development simulator. These simulators are based on the Monte Carlo method and a cell removal model, respectively. To avoid an excessive increase in calculation time, the calculation was performed with 100 nm×100 nm square cells at an accuracy larger than that desired. Also, the resist profile was estimated accurately by adopting the interpolation with the resultant cell profile. In the case of a chirped period grating of 5 mm in width, it took 24 h to calculate the optimum electron dose profile. Moreover to investigate the validity of this correction method a chirped period grating of 0.1 mm in width was fabricated with the calculated dose profile.