研磨パッドの粘弾性特性に着目した工作物エッジ・ロールオフ生成に関する検討(機械要素,潤滑,設計,生産加工,生産システムなど)

Abstract

Recently the achievement of further high flatness of workpiece is strongly required in mirror finishing. Especially the edge roll off of silicon wafers as the substrates of semiconductor devices is demanded to decrease in polishing process for raising the yield of IC chips. Many theoretical and experimental analyses for the edge roll off generation have been already done and the polishing methods for suppressing the roll off have been proposed to meet the demand. However, the analyses cannot fully account for the obtained edge shape in actual polishing and the problem about the roll off remains. In this study, the generation mechanism of the edge roll off based on the viscoelasticity of polishing pad as newly proposed. The mechanism considered the horizontal and vertical relative static and dynamic motion between the pad and the workpiece. Moreover, the non-contact viscoelasticity measurement instrument was originally developed to evaluate the viscoelasticity of the polishing pad precisely. A series of polishing experiments for silicon wafers revealed that the edge shape, which was induced from the edge roll off generation mechanism and the measured viscoelasticity of the polishing pad, corresponded well with the obtained edge shape.