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Ultra high precision Dual stage system Using Air bearing and VCM for Nano level Scanning  

Kim Ki-Hyun (한국과학기술원 기계공학과)
Gweon Dae-Gab (한국과학기술원 기계공학과)
Choi Young-Man (한국과학기술원 기계공학과)
Kim Dong-Min (한국과학기술원 기계공학과)
Nam Byoung-Uk (한국과학기술원 기계공학과)
Lee Suk-Won (삼성전자 지능시스템 연구소 메카트로닉스센터)
Lee Moon-Gu (삼성전자 지능시스템 연구소 메카트로닉스센터)
Publication Information
Journal of the Korean Society for Precision Engineering / v.22, no.5, 2005 , pp. 103-112 More about this Journal
Abstract
This paper presents one-axis high precision scanning system and illustrates the design of modified $X-Y-{\theta}$ stage as a tracker using VCM and commercialized air bearings for it. The scanning system for 100nm resolution is composed of the 3-axis stage and one axis long stroke linear motor stage as a follower. In this study a previous proposed and presented structure of VCM for the fine stage is modified. The tracker has 3 DOF($X-Y-{\theta}$ motions by four VCM actuators which are located on the same plane. So 4 actuating forces are suggested and designed to create least pitch and roll motions. This article will show about the design especially about optimal design. The design focus of this fine stage is to have high acceleration to accomplish high throughput. The optimal design of maximizing acceleration is performed in restrained size. The most sensitive constraint of this optimal design is heat dissipation of coil. There are 5 design variables. Because the relationship between design variables and system parameters are quite complicated, it is very difficult to set design variables manually. Due to it, computer based optimal design procedure using MATLAB is used. Then, this paper also describes the procedures of selecting design variables for the optimal design and a mathematical formulation of the optimization problem. Based on the solution of the optimization problem, the final design of the stage is also presented. The results can be verified by MAXWELL. The designed stage has the acceleration of about 5 $m/s^{2}$ with 40kg total mass including wafer chuck and interferometer mirror. And the temperature of coil is increased $50^{\circ}C$. In addition, the tracker is controlled by high precision controller system with HP interferometer for it and linear scaler for the follower. At that time, the scanning system has high precision resolution about 5nm and scanning resolution about 40nm in 25mm/s constant speed
Keywords
High precision; Scanning system; VCM; Dual Servo system;
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  • Reference
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