Effects of Various Facility Factors on Chemical Mechanical Polishing Process Defects

Abstract

The chemical mechanical polishing (CMP) process is widely used for the global planarization of the inter-metal dielectric (IMD) layer and inter-layer dielectric (ILD) for deep sub-micron technology. However, as the IMD layer and ILD become thinner, defects such as micro-scratches can lead to severe circuit failure, which affects yield. In this study, for the improvement of the CMP process, de-ionized water (DIW) pressure was varied, purified nitrogen (PN2) gas was used, and a point of use (POU) slurry filter and high spray bar (HSB) were installed. Our experimental results show that DIW pressure and PN2 gas factors were not related to removal rate, but the edge hot spot of the patterned wafer had a marked effect. Also, the filter installation in the CMP polisher could remarkably reduce the number of defects after CMP processing, thus it is shown that the slurry filter plays an important role in determining pad lifetime. However, the slurry filter cannot eliminate defect-causing particles completely. Thus, we suggest that it is necessary to install a high spray bar of de-ionized water (DIW) with high pressure, to overcome the weak points of a slurry filter.