Fast fabrication of silicon nanopillar array using electron beam lithography with two-layer exposure method

Abstract

Electron beam lithography (EBL) is one of the most popular and important technology in the nanofabrication fields for its high fabrication precision and flexibility. However, writing-time-consuming caused by the sequential patterning mechanism limits its wide application. Compared with the shapes with straight lines, the beam settling time during EBL writing for the curved shapes increases dramatically, therefore the curved structures would suffer longer writing time. Consequently, EBL is difficult to apply to the fabrication of the silicon nanopillar array with large area. In this paper, a two-layer exposure method in EBL (Raith EBPG5200) with Gaussian beam has been proposed to realize fast fabrication of large area silicon nanopillar array. The nanopillars are patterned by writing two layers of orthogonal gratings successively in one exposure job. The dose of overlap regions is twice as large as in other regions approximating rectangles to circles. The writing time is reduced to one forty-sixth of the conventional writing method, whereas the pattern fidelity is no impact. With this method, the controllable silicon nanopillars with diameters of 150 nm are fabricated. Results show that more than 85% of silicon nanopillars are within the deviation of 3.3% (145 nm to 155 nm) in diameter. This two-layer exposure method provides a practicable solution in the fabrication of large area nanopillar array.