Analysis of wafer edge pressure distribution using intelligent pad in chemical mechanical polishing

The pressure delivered the wafer is an element that plays an important role for its local and global planarization in a chemical mechanical polishing process. The non-uniform pressure distribution of the wafer edge especially produces productivity and economic loss in semiconductor device production, and the non-uniform pressure distribution is largely dependent on the pressure change of the retainer ring. The wafer pressure was fixed at 300g/cm², the retainer ring input pressure was changed to 300g/cm², 400g/cm² and 500g/cm², and the change of the pressure distribution in the wafer edge area was measured using an intelligent pad to which a sheet pressure sensor was attached. Pressure signal value that corresponds to each pixel in the pressure distribution image was extracted for the quantification of analysis. Thin-film thickness of the oxide wafer before and after polishing was measured and the tendency was compared to the material removal rate for the verification of the pressure signal value.