ボールねじステージにおける電磁ダンパ制御の一研究 : −ボールねじと小型リニアモータを組み合わせた高スループットステージの実現− A Study on Electromagnetic Damper Control for Ball Screw Stages : - Low Cost High Throughput Stage Using Ball Screw and Linear Motor Combination -

Linear motor drives became main streams of high-end lithography tool for semiconductor manufacturing. However ball screw drives with rotational motors are still important for rough layer lithography. A limitation of ball screw drives is due to stiffness of nut and screw. This stiffness will be changed gradually in use. Therefore its control gain has to have enough margins in order to keep robustness in industrial usages. This paper intends to improve the ball the screw stage stability using a small linear motor as an electromagnetic damper. This method can combine advantages of rotational motors and linear motors. The former is high efficiency, low cost and the latter is high stability because of direct drive. After detail experiments we found suitable control structure of electromagnetic damper which is inspired from grease characteristics in slide screw stages. It makes high accuracy and high throughput stage at the same time.