US Patent 9925637 Tapered poromeric polishing pad

The porous polyurethane polishing pad includes a porous polyurethane matrix having large pores extending upward from a base surface and open to a polishing surface. A series of pillow structures is formed from the porous matrix that include the large pores and the small pores. The pillow structures have a downward surface extending from the top polishing surface for forming downwardly sloped side walls at an angle from 30 to 60 degrees from the polishing surface. The large pores open to the downwardly sloped sidewalls and are less vertical than the large pores. The large pores are offset 10 to 60 degrees from the vertical direction in a direction more orthogonal to the sloped sidewalls.