Patent ID: 8083570
Filing Date: 2011-12-27
Classification: B24B

Abstract:
1. A multilayer chemical mechanical polishing pad for polishing a substrate selected from at least one of a magnetic substrate, an optical substrate and a semiconductor substrate; comprising: a polishing layer having a polishing surface, an outer perimeter and a polishing layer interfacial region parallel to the polishing surface; a porous subpad layer having a bottom surface, an outer perimeter and a porous subpad layer interfacial region parallel to the bottom surface; a pressure sensitive adhesive layer; and, a light transmissive window element; wherein the polishing layer interfacial region and the porous subpad layer interfacial region form a coextensive region; wherein the coextensive region secures the polishing layer to the porous subpad layer without the use of a laminating adhesive; wherein the pressure sensitive adhesive layer is applied to the bottom surface of the porous subpad layer; wherein an internal opening extends through the multilayer chemical mechanical polishing pad from the bottom surface to the polishing surface and is bounded by an internal peripheral edge of the porous subpad layer and a corresponding internal peripheral edge of the polishing layer; wherein the light transmissive window element is disposed within the internal opening and contacts the internal peripheral edge of the porous subpad layer; wherein the light transmissive window element is adhered to the pressure sensitive adhesive layer; wherein the porous subpad layer has been subjected to a first critical compressive force along the internal peripheral edge forming a first irreversibly collapsed, densified region of the porous subpad layer along the peripheral edge; wherein the porous subpad layer has been subjected to a second critical compressive force along the outer perimeter of the porous subpad layer forming a second irreversibly collapsed, densified region of the porous subpad layer along the outer perimeter of the porous subpad layer; wherein the polishing surface is adapted for polishing the substrate.