Effect of facility for hot spot reduction of inter-level dielectric (ILD) CMP process

Chemical mechanical polishing (CMP) process is widely used for global planarization of inter-level dielectric (ILD) for sub-micron technology. But the hot-spot due to partial over-polishing was generated in the edge of wafers, and became a major concern. Thus, it is very important to understand the correlation between ILD-CMP process and various facility factors of CMP equipment system. With facility shortage of deionized water (DIW) pressure, we introduced an adding purified N ₂ (PN₂) gas in polishing head cleaning station for increasing a cleaning effect. Our experimental results show that DIW pressure and PN₂ gas factors were not related with removal rate, but edge hot-spot of patterned wafer had a serious relation. We estimated two factors (DIW pressure and PN₂ gas) for the improvement of CMP process. Especially, we obtained a uniform planarity in patterned wafer and prohibited more than 90% of wafer edge over-polishing. Finally, we suggest that the facility factors supplied to equipment system play an important role in ILD-CMP process