Advantages of point of use (POU) slurry filter and high spray method for reduction of CMP process defects
As integrated circuit devices shrink to smaller dimensions, a chemical mechanical polishing (CMP) process was required for the global planarization of the inter-metal dielectric (IMD) layer with free-defects. However, as the IMD layer gets thinner, micro-scratches are becoming a major defect. Micro-scratches are generated by agglomerated slurry, solidified and attached slurry in the pipeline of the slurry supply system. In order to prevent the agglomerated slurry particles from slurry inflow, we installed a 0.5 ?m point of use (POU) filter, which is a depth-type filter and has 80% filtering efficiency for 1.0 ?m size particles. Also a high spray bar of de-ionized water with high pressure was installed in the CMP equipment. Our experimental results showed that it is impossible to completely prevent defect-causing particles through the depth-type filter. Thus, we suggest that it is necessary to optimize the slurry flow rate and to install a high spray bar of de-ionized water (DIW) with high pressure, in order to overcome the weak points of a POU depth-type filter.
point of use (pou) chemical mechanical polishing (cmp) inter-metal dielectric (imd) high spray bar de-ionized water (diw)