Servo System Design for Nano Pattern-Stitching in an Electron Beam Lithography System
Date Issued
2010
Date
2010
Author(s)
Chiu, Pablo
Abstract
Electron beam lithography has become one of the most promising candidates of next-generation lithography technologies. Then, pattern-placement inaccuracy will be a challenging research topic when maskless electron beam direct-write lithography is used. In order to correct the field-stitching errors, a high-resolution nano stage is integrated into the original stage (JEOL JSM 7000F SEM). The wafer is placed on the highly accurate laser-interferometer-controlled-stage, and patterns are written with reference mirrors on the stage. A feedback controller is used for pattern-placement. Piezoelectric actuators are used to drive the fine stage, and it compensates the insufficient resolution of the coarse stage. The piezo-stage is demonstrated to be nearly decoupled and the non-linear behavior is overcome with PID controllers. The long travel-range of the coarse stage allows us to achieve exposures of millimeter-range areas. Large displacement pattern-stitching are demonstrated in the experimental results.
Subjects
Electron-beam lithography
pattern-stitching
nano-stage
piezoelectric transducer
laser-beam interferometer system
PID controller
Type
thesis
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