Patent ID: 7862316

Claim:
Apparatus for fabricating foamed thermoplastic polymeric mechanical planarization polishing pads using supercritical fluid, the apparatus comprising: a mechanical planarization polishing pad mold; an extrusion system used for molding a solid thermoplastic polymer in a mechanical planarization polishing pad mold to form an unfoamed thermoplastic polymeric pad; an extrusion screw used for impregnating said unfoamed thermoplastic polymeric pad with a supercritical fluid foaming agent; a plurality of discontinuous screw flights of said extrusion screw for mixing said unfoamed thermoplastic polymeric pad with said supercritical fluid foaming agent to achieve a desired cell density of a foamed thermoplastic polymeric mechanical planarization polishing pad; a foaming chamber; a nucleator comprising a plurality of restrictive pathways positioned between the extrusion screw and the foaming chamber; and a temperature control unit and a pressure control unit, positioned on the exterior of said foaming chamber, used for foaming said unfoamed thermoplastic polymeric pad to produce said foamed thermoplastic polymeric mechanical planarization polishing pad, wherein in response to said desired cell density, said temperature control unit and said pressure control unit are set to: a process temperature; a process pressure; a rate of temperature increase; and a pressure drop rate.