Variation of polish pad shape during pad dressing

In silicon wafer polishing and CMP processes, polish pad dressing (conditioning) is often used to restore pad performance. In this report, variation of polish pad shape during dressing is studied by using diamond-plated cup wheels and sandpaper rings, respectively. Result shows that pad shape becomes concave after certain amount of dressing. The concavity increases with dressing time – longer dressing produces higher concavity. Moment induced by the frictional force between pad and dressing device is proposed to explain the pad shape variation.