Patent ID: 8408977

Claim:
A polishing pad having a polishing surface useful for polishing at least one of magnetic, optical and semiconductor substrates, comprising a porous polishing layer, the porous polishing layer having a dual porosity structure within a polyurethane matrix, the dual porosity structure having a primary set of pores, the primary set of pores being open to the polishing surface, having an elongated structure orthogonal to the polishing surface and having pore walls, the pore walls having a thickness of 15 to 55 μm, a storage modulus of 10 to 60 MPa measured at 25° C. and containing a secondary set of pores within the pore walls, the secondary set of pores being more spherical than the primary set of pores and having an approximately spherical shape and having an average pore size of 5 to 30 μm and wherein the porous polishing layer is formed into a woven or non-woven structure to form the polishing pad and the polishing layer includes a groove pattern.