Active Vibration Correction in Electron Beam Lithography System

Abstract

In an electron beam (EB) lithography system, beam positional vibration is one of the most influential factors of positioning accuracy degradation. We propose a new correction method for improving this accuracy and investigate its effectiveness by applying it to a nanometer EB system. In our method, first, the correction signal is generated by detecting the beam positional vibration as the variation of the backscattered or the transmitted electron signal and then extracting one period of this signal. Then, the correction signal is added to that of the beam deflection control. The effectiveness of this correction is evaluated by measuring beam positional vibration and stitching accuracy of the delineated pattern between subfields with size of 8 µ m×8 µ m. As a result, both an amplitude of the beam vibration of less than 10 nm and a stitching accuracy of less than 8 nm (3σ) are achieved, which confirms that the beam vibration has been actively corrected, and the positioning accuracy has been improved. The above results indicate that this correction method is very valuable for the EB lithography system.