Polishing pad and production method thereof

Abstract

There are provided a polishing pad which exhibits excellent polishing stability and excellent slurry retainability during polishing and even after dressing, can prevent a reduction in polishing rate effectively and is also excellent in an ability to flatten an substrate to be polished, and a method for producing the polishing pad. The method comprises dispersing water-soluble particles such as β-cyclodextrin into a crosslinking agent such as a polypropylene glycol so as to obtain a dispersion, mixing the dispersion with a polyisocyanate such as 4,4′-diphenylmethane diisocyanate and/or an isocyanate terminated urethane prepolymer, and reacting the mixed solution so as to obtain a polishing pad having the water-soluble particles dispersed in the matrix.

What is claimed is:  
     
         1 . A method for producing a polishing pad, comprising the steps of: 
 dispersing water-soluble particles in a crosslinking agent to produce a dispersion,    mixing the dispersion with a polyisocyanate and/or an isocyanate terminated urethane prepolymer to produce a mixed solution, and    reacting the mixed solution to produce a polishing pad comprising a polishing layer having the water-soluble particles dispersed in a polymer matrix.    
     
     
         2 . The method of  claim 1 , wherein the crosslinking agent has at least two functional groups each of which has an active hydrogen atom reactable with an isocyanate group, in a molecule.  
     
     
         3 . The method of  claim 1 , wherein the crosslinking agent is a polyol and/or a polyamine.  
     
     
         4 . The method of  claim 1 , wherein the crosslinking agent comprises a component having a number average molecular weight of not higher than 5,000 in an amount of not smaller than 30 wt % based on 100 wt % of the crosslinking agent.  
     
     
         5 . The method of  claim 1 , wherein: 
 the crosslinking agent is a polyol,    in the step of producing the mixed solution, an isocyanate terminated urethane prepolymer, or a polyisocyanate and an isocyanate terminated urethane prepoloymer is/are used, the isocyanate terminated urethane prepolymer is obtained by reacting a compound having at least two hydroxyl groups in a molecule with a polyisocyanate in an equivalent ratio of the hydroxyl group (OH group) to an isocyanate group (NCO group) of 1/1.8 to 1/2.4, and    the equivalent ratio of hydroxyl groups in the crosslinking agent to isocyanate groups in the isocyanate raw material (OH group/NCO group) is 1/0.9 to 1/1.4.    
     
     
         6 . The method of  claim 5 , wherein the polyol is a diol and/or a triol.  
     
     
         7 . A polishing pad obtained according to the method of  claim 1 , comprising a polishing layer having water-soluble particles dispersed in a polymer matrix.  
     
     
         8 . The polishing pad of  claim 7 , wherein the volume of the water-soluble particles is 0.5 to 70% by volume when the volume of the polishing layer in the polishing pad is 100%.  
     
     
         9 . The polishing pad of  claim 7 , wherein a tensile product for a tensile test at a temperature of 30° C. and a pulling rate of 500 mm/min is 50 to 20,000 kgf/cm.