Impact of Novel Pad Groove Designs on Removal Rate and Uniformity of Dielectric and Copper CMP

The effect of pad surface texture on dielectric and copper removal rates was studied theoretically and experimentally by investigating the fluid behavior of the slurry layer using methodologies similar to those found in tribological investigations of fluid bearings. It is shown that new nonfoamed hard plastic pads with intricate groove patterns are critical in modulating removal rates. Removal rate results of dielectric chemical mechanical polishing were in close agreement with model predictions for several of the groove designs tested. Combined patterns, consisting of spiral and logarithmic grooves, were shown to impact several key attributes of the dielectric and copper processes in terms of slurry retention, hydrodynamic pressure, tribological mechanism, and material removal rates.