Optimization of CMP Pad Surface by Laser Induced Micro Hole

Abstract

In this paper, the optimization of the chemical mechanical planarization (CMP) pad design is investigated to reduce defect generation during the CMP process. Recently, obtaining the optimum performance from the viewpoint of scratch generation has become the most challenging area in the CMP process. To achieve uniform performance of the process at the defect level, the surface texture and/or groove of the CMP pads should be designed effectively, and their original surface should be maintained throughout their lifetime. Because the transport of slurry and wear debris, which is the source of CMP scratches, is highly dependent on the surface geometry of the CMP pad, maintaining suitable process conditions is considered the most important design factor. In this work, the surface geometries of two CMP pads with different body structures are modified by a laser-induced micro hole; one is a porous-type pad and the other is a nonporous type. Based on the experimental and numerical simulation results, the micro-hole induced pads had a lower defect level than the conventional porous pads without holes because the micro holes acted as a defect source or coarse particle reservoir to prevent micro scratch during the process. In addition, the micro holes of the porous pad showed a lower defect generation than the holes of the nonporous pad as the process time increased.