Effects of deionized water pressure and purified nitrogen gas on the chemical mechanical polishing process

The chemical mechanical polishing (CMP) process is widely used for the global planarization of inter-layer dielectric (ILD) for deep sub-micrometer technology. But hot-spots due to partial over-polishing generated in the edges of wafers, have become a major concern. Thus, it is very important to understand the correlation between the ILD-CMP process and various facility factors of the CMP equipment system. With a facility shortage of de-ionized water (DIW) pressure, we introduced an additional purified nitrogen (PN2) gas in the polishing-head-cleaning station to increase the cleaning effect. Our experimental results show that DIW pressure and PN2 gas factors were not related to the removal rate, but edge hot-spots on the patterned wafer had a strong relation with them. We estimated two factors (DIW pressure and PN2 gas) for the improvement of the CMP process. In particular, we obtained a uniform planarity in the patterned wafer and prevented more than 90% of wafer edge over-polishing. Finally, we suggest that the facility factors for an equipment system play an important role in the ILD-CMP process. (C) 2002 Kluwer Academica Publishers.