Dual-layer cmp polishing subpad

Abstract

The invention provides a porous subpad for a chemical mechanical polishing pad comprising a polishing layer having a polymeric matrix, a polishing surface useful for polishing at least one of semiconductor, magnetic and optical substrates and a bottom surface. The porous subpad includes a non-porous layer having a polymeric matrix and a multilayer having a micro-scale negative impression of the bottom surface of the polishing pad. The multilayer is closed cell, open cell or a mixture of closed and open cell micropores that are gas filled; and the multilayer remains gas filled during an entire polishing life of the polishing pad.

We claim: 
     
         1 . A chemical mechanical polishing pad comprising:
 a polishing layer having a polymeric matrix, a polishing surface useful for polishing at least one of semiconductor, magnetic and optical substrates and a bottom surface;   a porous subpad adhered to the bottom surface of the polishing pad, the porous subpad including:   a non-porous layer for securing the polishing pad to the porous subpad, the non-porous layer having a polymeric matrix and having a micro-scale negative impression of the bottom surface of the polishing pad and the non-porous layer being contiguous with the bottom surface of the polishing layer; and   a multilayer of closed cell, open cell or a mixture of closed and open cell micropores wherein the multilayer of closed cell, open cell or a mixture of closed and open cell micropores are gas filled and the multilayer remains gas filled during an entire polishing life of the polishing pad and wherein the multilayer of closed cell, open cell or a mixture of closed and open cell micropores has the same polymeric matrix of the nonporous layer and a flexibility greater than the non-porous layer.   
     
     
         2 . The polishing pad of  claim 1  wherein the non-porous microlayer has an average thickness of at least two hundred percent of an average diameter of the closed cell micropores within the polymer network. 
     
     
         3 . The polishing pad of  claim 1  wherein the multilayer includes the mixture of closed and open micropores and the closed cells are spherical and the ovoid micropores include open cells. 
     
     
         4 . The polishing pad of  claim 1  wherein the multilayer includes the mixture of closed cell and open cell micropores and the closed cells are spherical and the open cell pores include ovoid-shaped micropores. 
     
     
         5 . The polishing pad of  claim 1  wherein the polishing layer has a bottom surface and the bottom surface includes annular grooves that extend into the polishing layer without piercing through the polishing surface of the polishing layer and the subpad fills the annular grooves. 
     
     
         6 . A chemical mechanical polishing pad comprising:
 a polishing pad having a polymeric matrix, a polishing surface useful for polishing at least one of semiconductor, magnetic and optical substrates and a bottom surface;   a porous subpad adhered to the bottom surface of the polishing pad, the porous subpad including:   a non-porous layer for securing the polishing pad to the porous subpad, the non-porous layer having a polymeric matrix and having a micro-scale negative impression of the bottom surface of the polishing pad and the non-porous layer being contiguous with the bottom surface of the polishing layer; and   a multilayer of closed cell, open cell or a mixture of closed and open cell micropores wherein the multilayer of closed cell, open cell or a mixture of closed and open micropores are gas filled and the multilayer remains gas filled during an entire polishing life of the polishing pad and wherein the multilayer of closed cell, open cell or a mixture of closed and open cell micropores has the same polymeric matrix of the low porosity layer and a flexibility greater than the nonporous layer and the polishing pad has a porosity and the porous subpad has a porosity greater than the porosity of the polishing pad.   
     
     
         7 . The polishing pad of  claim 6  wherein the non-porous microlayer has an average thickness of at least two hundred percent of an average diameter of the closed cell micropores within the polymer network. 
     
     
         8 . The polishing pad of  claim 6  wherein the multilayer includes the mixture of closed and open micropores and the closed cells are spherical and the ovoid micropores include open cells. 
     
     
         9 . The polishing pad of  claim 6  wherein the multilayer includes the mixture of closed cell and open cell micropores and the closed cells are spherical and the open cell pores include ovoid-shaped micropores. 
     
     
         10 . The polishing pad of  claim 6  wherein the multilayer includes a macro feature that extends into the subpad for adjusting polishing profile of the chemical mechanical polishing pad.