Miniature electron beam lithography system for micro/nanometer pattern fabrication

To satisfy the requirement of fabricating semiconductor devices or micro/nano structure, and to avoid expensive cost of industrial electron beam lithography (EBL) machine, a desktop EBL system was developed based on a normal scanning electron microscopy (SEM) and fabrication techniques. The high speed pattern generator hardware system was set up with a floating-point digital signal processor (DSP) as the core controller. The EBL field calibration coefficients including gain, rotation and shift were calculated by linearity method. In order to achieve nanometer positioning accuracy, a novel precision stage driven by piezoelectric motors was used. Depending on the stage's nanometer positioning ability, mark chasing method was used for calibrating the EBL field size and shape. The lithography results show that stitching and overlay error is less than 100 nm. For testing the lithography resolution, parallel lines less than 30 nm in width were etched on resistant PMMA. Following a lithography test on SU8 and PMMA bilayer resists, the EBL process of nitride phase-change electrode was accomplished by EBL stitching and overlay methods.