Analysis on Pad Surface Roughness of Diamond Conditioning Process for CMP

Abstract

Chemical Mechanical Polishing/Planarization (CMP) is the key process of the wafer and thin film planarization process for semiconductor manufacturing. In the CMP process, the pad can restore its surface topography and efficiency by diamond conditioner or named as diamond conditioning process. The pad surface roughness is essential to the removal rate in the CMP process because it can represent the contact level of the polishing pad and wafer. This study has developed a simulation program based on precise diamond-grits conditioning routes and numbers of cross points. By studying the OP (overlap cutting points) distribution in a specific area on the pad which is generated by CL (cutting locus), the trend of roughness parameters is discovered. The simulation and experimental model can be effective to observe pores deformation and predict pad surface topography. The results show the pad roughness would become steady over a certain OP number, and the OP can be precisely calculated and compared to the actual pad surface. The final results of the break-in and pad conditioning process can be estimated or further optimized. The other high-density and customized diamond-grits arrangement of conditioner can be designed according to the study in future work.

Characterization and dressing effect of CMP diamond disc conditioner with ordered abrasive distribution

“…Pham [17] verified that the roughness of the polishing pad will be greater where the grain trajectories overlap, and divided the polishing pad into multiple concentric circles, and compared the number of track coincidence points in each concentric circle to predict the polishing pad roughness distribution. Li [18] found that the intersection density of grain tracks affects the pad roughness, and the pad roughness becomes stable only when the track overlap density reaches a certain amount. Eungchul [19] conducted a topological analysis of the dressing process in CMP to calculate the amount of polishing pad wear caused by the movement of grains, the wear depth of the polishing pad was analyzed under the condition of equal pressure, and the dressing effect of the polishing pad was obtained by simulating the dressing process.…”