Design And Research Of Vertical High Precision Movement Mechanism For Wafer Inspection Stage

Nowadays wafer surface inspection plays an increasingly important role in ICmanufacturing. In order to improve inspection efficiency to increase productivity, thestage must be highly rotated and move in a continuous fed spiral manner for inspection.The impact that the wafer surface deviates from the focal plane of the optical detector iscaused by he axial runout of Rotary motion, which results in poor image quality. Thevertical positioning accuracy of the stage must be of0.5μm for the next45-22nm processnode, which poses a challenge to the design and control for vertical motion mechanism ofthe wafer inspection stage.This thesis mainly carries out the overall concept design component selection, structuraldesign and analysis, design of vertical positioning control system and correspondingexperimental research. The main work and results are as follows:Based on the overall requirements of wafer inspection stage, the Performance needand function need of Precision vertical motion mechanism is analyzed. The proposal thatuses Scroll rail guide, Cylinder balance gravity, Voice coil motor to accomplish theposition of Compensation control is proposed, which also meets the need of Large verticalstroke movement in Changer process and precise position in inspection.Analysis, selection and verification research of critical component including cylinder,voice coil motors, encoders and rolling guide are accomplished. The structual design andthe prototype of vertical high precision movement mechanism are finished. The design ofprecision positioning control system for vertical high precision movement mechanism isdeveloped, and the effect of current, speed and position PID feedback control aresamulated.The precision positioning control experiments are conducted. The results show that itsvertical positioning accuracy is of0.1μm. Besides, the ability that tracks micron smallfluctuations of the vertical high precision movement mechanism is fully tested andverified, which builds the foundation of compensating micron straightness deviation of themicron axial runout of horizontal guide and air-bearing rotary table by using thismechanism.