Cerium salt, producing method thereof, serium oxide and cerium based polishing slurry

Abstract

A cerium salt wherein, when 20 g of the cerium salt is dissolved in a mixed liquid of 12.5 g of 6N nitric acid and 12.5 g of a 30% hydrogen peroxide aqueous solution, a concentration of an insoluble component present in the solution is 5 ppm or less by mass ratio to the cerium salt before dissolution and cerium oxide produced by processing the cerium salt at high temperatures. Scratch on a surface to be polished can be reduced when a cerium based polishing slurry containing the cerium oxide particles is used, since an amount of impurities in cerium oxide particles and cerium salt particles, raw material thereof, is reduced for high purification.

1 - 11 . (canceled) 
     
     
         12 . A cerium based polishing slurry, comprising cerium oxide,
 wherein said cerium oxide is obtained by subjecting a cerium salt to a high temperature process of 250° C. or more,   wherein said cerium salt has the property of when 20 g of said cerium salt is dissolved in a mixed liquid of 12.5 g of 6N nitric acid and 12.5 g of a 30% hydrogen peroxide aqueous solution, a concentration of an insoluble component present in the solution is l ppm or less by mass ratio.   
     
     
         13 . A cerium based polishing slurry,
 wherein said cerium based polishing slurry has the property of when 20 g of the dried matter containing cerium oxide particles obtained by drying the cerium based polishing slurry is dissolved in a mixed liquid of 12.5 g of 6N nitric acid and 12.5 g of a 30% hydrogen peroxide aqueous solution, a concentration of an insoluble component present in the solution is 1 ppm or less by mass ratio.   
     
     
         14 . The cerium based polishing slurry according to  claim 12 ,
 wherein said cerium oxide has the property of when 20 g of said cerium oxide is dissolved in a mixed liquid of 12.5 g of 6N nitric acid and 12.5 g of a 30% hydrogen peroxide aqueous solution, a concentration of an insoluble component present in the solution is 10 ppm or less by mass ratio.   
     
     
         15 . The cerium based polishing slurry according to  claim 12 , wherein the cerium oxide is pulverized mechanically. 
     
     
         16 . The cerium based polishing slurry according to  claim 12 , wherein the cerium oxide is dispersed in water. 
     
     
         17 . The cerium based polishing slurry according to  claim 12 , which further comprises a dispersing agent. 
     
     
         18 . The cerium based polishing slurry according to  claim 17 , wherein a weight average molecular weight of the dispersing agent is in the range of 100 to 50,000. 
     
     
         19 . The cerium based polishing slurry according to  claim 12 , wherein the cerium salt includes cerium carbonate. 
     
     
         20 . The cerium based polishing slurry according to  claim 12 , wherein a median value of secondary particle diameters of the cerium oxide particles in the cerium based polishing slurry is in the range of 0.01 to 1.0 μm. 
     
     
         21 . The cerium based polishing slurry according to  claim 13 , wherein the cerium oxide is pulverized mechanically. 
     
     
         22 . The cerium based polishing slurry according to  claim 13 , wherein the cerium oxide is dispersed in water. 
     
     
         23 . The cerium based polishing slurry according to  claim 13 , which further comprises a dispersing agent. 
     
     
         24 . The cerium based polishing slurry according to  claim 23 , wherein a weight average molecular weight of the dispersing agent is in the range of 100 to 50,000. 
     
     
         25 . The cerium based polishing slurry according to  claim 13 , wherein a median value of secondary particle diameters of the cerium oxide particles in the cerium based polishing slurry is in the range of 0.01 to 1.0 μm.