Polishing slurry and polishing method using same

Abstract

Polishing slurry is caused to be present between a surface of a soft magnetic layer and a polishing tool such as a polishing pad and the surface of the soft magnetic layer and the polishing tool are moved relative to each other. The polishing slurry contains silica particles as abrading particles, compounds containing carboxylic acid and amino polycarboxylic acid and an oxidizing agent as a polishing accelerator, organic and/or inorganic compound of phosphoric acid, nitride and/or nitrite as an anti-corrosion agent and a pH conditioner such that the slurry has pH value between 4 and 11.

1 . Polishing slurry for polishing the surface of a soft magnetic layer formed on the surface of a substrate for a perpendicular magnetic recording hard disk, said polishing slurry comprising:
 abrading particles;   a polishing accelerator;   an anti-corrosion agent;   a pH conditioner; and   water;   wherein said abrading particles include silica particles;   wherein said polishing accelerator includes a compound containing carboxylic acid, a compound containing amino polycarboxylic acid and an oxidizing agent;   wherein said anti-corrosion agent includes one or more compounds selected from the group consisting of organic and inorganic compounds of phosphoric acid, nitrides and nitrites; and   wherein said polishing slurry is conditioned to be between pH4 and pH 11 by said pH conditioner.   
     
     
         2 . The polishing slurry of  claim 1  wherein at least either of said compound containing carboxylic acid and said compound containing amino polycarboxylic acid is ammonium salt. 
     
     
         3 . The polishing slurry of  claim 1  wherein said oxidizing agent is hydrogen peroxide water. 
     
     
         4 . The polishing slurry of  claim 1  wherein the pH value of said polishing slurry is less than 7 and said anti-corrosion agent comprises an organic or inorganic compound of phosphoric acid. 
     
     
         5 . The polishing slurry of  claim 1  wherein the pH value of said polishing slurry is more than 7 and said anti-corrosion agent comprises a nitride. 
     
     
         6 . The polishing slurry of  claim 1  wherein the pH value of said polishing slurry is less than 7 and said pH conditioner comprises hydroxylic acids. 
     
     
         7 . The polishing slurry of  claim 1  wherein the pH value of said polishing slurry is more than 7 and said pH conditioner comprises an amine. 
     
     
         8 . The polishing slurry of  claim 1  wherein said silica particles comprise colloidal silica with an average particle diameter of 5 nm or more and 300 nm or less. 
     
     
         9 . The polishing slurry of  claim 1  wherein said silica particles comprise colloidal silica with an average particle diameter of 20 nm or more and 100 nm or less. 
     
     
         10 . The polishing slurry of  claim 1  wherein said silica particles are contained at a rate of 1 weight % or more and 30 weight % or less of the total weight of said polishing slurry;
 wherein said compound containing carboxylic acid and said compound containing amino polycarboxylic acid are together contained at a rate of 0.01 weight % or more and 20 weight % or less of the total weight of said polishing slurry;   wherein said oxidizing agent is contained at a rate of 0.1 weight % or more and 20 weight % or less of the total weight of said polishing slurry; and   wherein said anti-corrosion agent is contained at a rate of 0.001 weight % or more and 5 weight % or less of the total weight of said polishing slurry.   
     
     
         11 . A method of polishing the surface of a soft magnetic layer formed on the surface of a substrate for a perpendicular magnetic recording hard disk; said method comprising the steps of:
 causing polishing slurry to be present between said surface of said soft magnetic layer and a polishing tool; and   causing said surface of said soft magnetic layer and said polishing tool to move relative to each other;   wherein said polishing slurry comprises:   abrading particles;   a polishing accelerator;   an anti-corrosion agent;   a pH conditioner; and   water;   wherein said abrading particles include silica particles;   wherein said polishing accelerator includes a compound containing carboxylic acid, a compound containing amino polycarboxylic acid and an oxidizing agent;   wherein said anti-corrosion agent includes one or more compounds selected from the group consisting of organic and inorganic compounds of phosphoric acid, nitrides and nitrites; and   wherein said polishing slurry is conditioned to be between pH4 and pH11 by said pH conditioner.   
     
     
         12 . The method of  claim 11  wherein said polishing tool comprises a polishing pad.