Ultra-precision 3 DOF tilting stage for workpiece setup of scalable micro-pattern machining

Micro-machining has been widely used for manufacturing of micro molds for flat panel displays. Because the mold has a large area and heavy weight, the workpiece setup system with a high stiffness and ultraprecise positioning control is required to obtain a longterm manufacturing stability and precision. In this study, a novel ultra-precision tilting stage with 3-DOF motions (z-translation, pitch, and roll) has been developed to setup a heavy duty and large area workpiece. The structure is designed to realize a long motion range via an amplified guide mechanism of high stiffness flexure guide and the piezo-electric actuators are integrated to achieve the motion resolution of less than 100 nm. The guide mechanism has a large stiffness with long-term stability through the unique combination of a closed-lying bridge and a half-standing bridge, which can amplify the motion rage double and minimize the overall volume of tilting system. The static, dynamic, and thermal characteristic of the system was optimized by structural analysis using finite element modeling. Finally, the tilting stage provides 50 nm positioning repeatability for a workpiece of 150 kg within a vertical stroke of 160 mu m and a machining area of 400x400 mm(2).