Method for manufacturing microporous CMP materials having controlled pore size

Abstract

A method of manufacturing a chemical-mechanical polishing (CMP) pad comprises the steps of (a) forming a layer of a polymer resin liquid solution (i.e., a polymer resin dissolved in a solvent); (b) inducing a phase separation in the layer of polymer solution to produce an interpenetrating polymeric network comprising a continuous polymer-rich phase interspersed with a continuous polymer-depleted phase in which the polymer-depleted phase constitutes about 20 to about 90 percent of the combined volume of the phases; (c) solidifying the continuous polymer-rich phase to form a porous polymer sheet; (d) removing at least a portion of the polymer-depleted phase from the porous polymer sheet; and (e) forming a CMP pad therefrom. The method provides for microporous CMP pads having a porosity and pore size that can be readily controlled by selecting the concentration polymer resin in the polymer solution, selecting the solvent based on the solubility parameters of the polymer in the solvent polarity of solvent, selecting the conditions for phase separation, and the like.

1 . A chemical mechanical polishing (CMP) pad comprising a porous polymeric sheet and defining a network of substantially interconnected pores having a porosity in the range of about 20 to about 90 percent, the network of pores comprising pores having diameters in the range of about 0.01 to about 10 microns and having a pore size distribution in which at least about 75% of the pores have a pore size within 5 microns of the average pore size.  
     
     
         2 . The CMP pad of  claim 1  wherein the network of pores comprises pores having diameters in the range of about 0.1 to about 5 microns.  
     
     
         3 . The CMP pad of  claim 1  wherein the network of pores comprises pores having diameters in the range of about 0.01 to about 2 microns.  
     
     
         4 . The CMP pad of  claim 1  wherein the polymeric sheet has a porosity in the range of about 20 to about 30 percent.  
     
     
         5 . The CMP pad of  claim 1  wherein the polymeric sheet has a porosity in the range of about 70 to about 90 percent.  
     
     
         6 . The CMP pad of  claim 1  wherein the polymer sheet comprises a polymer resin selected from the group consisting of a thermoplastic elastomer, a thermoplastic polyurethane, a thermoplastic polyolefin, a polycarbonate, a polyvinylalcohol, a nylon, an elastomeric rubber, an elastomeric polyethylene, a polytetrafluoroethylene, a polyethyleneteraphthalate, a polyimide, a polyaramide, a polyarylene, a polystyrene, a polymethylmethacrylate, a copolymer thereof, and a combination of two or more of the foregoing.  
     
     
         7 . The CMP pad of  claim 1  wherein the polymeric sheet comprises a thermoplastic polyurethane.  
     
     
         8 . The CMP pad of  claim 1  wherein the pad has a transmittance of about at least about 10% for light having a wavelength in the range of about 540 to about 560 nm, as measured through a 0.15 cm thick portion of the pad.