Effects of Chemical Mechanical Polishing Parameters on Acoustic Emission Characteristics

Chemical mechanical polishing (CMP) is a dominating way to realize global planarization of wafers, and acoustic emission is very sensitive to material damage. So it is of great significance to investigate acoustic emission characteristics during CMP for CMP mechanism research and process monitoring. Here acoustic emission characteristics and signal generating mechanism during CMP were studied using copper, a kind of interconnection material of semiconductors. The results demonstrate that the intensity of acoustic emission signal increases with the increase of polishing pressure and pad rotational speed. The signal is obviously influenced by the ingredient of liquid pumped in as well. Besides, signal energy distributes mainly within two frequency bands, and the higher frequency component is able to characterize scratches during CMP.