Polishing slurry, method of producing same, and method of polishing substrate

Abstract

Disclosed is a polishing slurry, particularly, a slurry for chemical mechanical polishing, which is used in a chemical mechanical polishing process for flattening a semiconductor laminate. More particularly, the present invention provides a method of producing a slurry which has high removal selectivity to a nitride layer used as a barrier film in a shallow trench isolation CMP process needed to fabricate ultra highly integrated semiconductors of 256 mega D-RAM or more (Design rule of 0.13 μm or less) and which decreases the occurrence of scratches on a flattened surface, and a method of polishing a substrate using the same.

1 . A polishing slurry, comprising: 
 polishing particles in which a surface area per unit weight is changed so as to minimize agglomeration of the polishing particles and improve dispersion stability.    
     
     
         2 . The polishing slurry as set forth in  claim 1 , wherein the surface area per unit weight of the polishing particles is 1-100 m 2 /g.  
     
     
         3 . The polishing slurry as set forth in  claim 1 , wherein the surface area per unit weight of the polishing particles is 3-72 m 2 /g.  
     
     
         4 . The polishing slurry as set forth in  claim 1 , wherein the surface area per unit weight of the polishing particles is 5-25 m 2 /g.  
     
     
         5 . The polishing slurry as set forth in  claim 1 , wherein a grain size of each of the polishing particles is 15-40 nm.  
     
     
         6 . The polishing slurry as set forth in  claim 1 , wherein a grain size of each of the polishing particles is 18-30 nm.  
     
     
         7 . The polishing slurry as set forth in  claim 1 , wherein a grain size of each of the polishing particles is 20-25 nm.  
     
     
         8 . The polishing slurry as set forth in  claim 1 , wherein the surface area per unit weight of the polishing particles is controlled depending on a temperature or a holding time of a calcination process.  
     
     
         9 . A polishing slurry, which comprises polishing particles, deionized water, and a dispersing agent, in which agglomeration of the polishing particles is minimized and a variation (dD50) of a median particle size of the polishing particles is 30 or less before and after forcible dispersion treatment, by controlling an amount of dispersing agent added or a stage at which the dispersing agent is added.  
     
     
         10 . The polishing slurry as set forth in  claim 9 , wherein the variation (dD50) of the median particle size of the polishing particles is 10 or less.  
     
     
         11 . The polishing slurry as set forth in  claim 9 , wherein conductivity of the polishing slurry is 300-900 μs/cm.  
     
     
         12 . The polishing slurry as set forth in  claim 9 , wherein conductivity of the polishing slurry is 500-600 μs/cm.  
     
     
         13 . The polishing slurry as set forth in  claim 9 , wherein the dispersing agent is made of an anionic polymer compound, and the anionic polymer compound is at least one selected from a group consisting of polymethacrylic acid, polyacrylic acid, ammonium polymethacrylate, ammonium polycarboxylate, and carboxyl-acryl polymer.  
     
     
         14 . The polishing slurry as set forth in  claim 1 , wherein the polishing particles are ceria.  
     
     
         15 . A method of producing a polishing slurry, comprising: 
 preparing polishing particles, deionized water, and a dispersing agent;    preparing a mixture of the polishing particles, the deionized water, and the dispersing agent; and    milling the mixture of the polishing particles, the deionized water, and the dispersing agent.    
     
     
         16 . The method as set forth in  claim 15 , wherein the preparation of the mixture of the polishing particles, the deionized water, and the dispersing agent comprises: 
 milling a mixture of the polishing particles and the deionized water;    measuring a pH of the mixture of the polishing particles and the deionized water;    determining an amount of dispersing agent to be added, depending on the pH; and    mixing the dispersing agent with the mixture of the polishing particles and the deionized water.    
     
     
         17 . The method as set forth in  claim 16 , wherein the amount of dispersing agent added is 2.2-3.0 wt % based on the polishing particles when the pH of the mixture of the polishing particles and the deionized water is 8.7-9.5 in the determination of the amount of dispersing agent.  
     
     
         18 . The method as set forth in  claim 16 , wherein the amount of dispersing agent added is 1.4-2.2 wt % based on the polishing particles when the pH of the mixture of the polishing particles and the deionized water is 8.0-8.7 in the determination of the amount of dispersing agent.  
     
     
         19 . The method as set forth in  claim 16 , wherein the amount of dispersing agent added is 0.6-1.4 wt % based on the polishing particles when the pH of the mixture of the polishing particles and the deionized water is 7.4-8.0 in the determination of the amount of dispersing agent.  
     
     
         20 . The method as set forth in  claim 15 , wherein the preparation of the mixture comprises: 
 adding the dispersing agent to the deionized water and mixing them; and    mixing the polishing particles with the deionized water to which the dispersing agent is added.    
     
     
         21 . The method as set forth in  claim 15 , wherein the preparation of the mixture comprises: 
 adding the polishing particles to the deionized water; and    mixing the dispersing agent with the deionized water to which the polishing particles are added.    
     
     
         22 . The method as set forth in  claim 15 , wherein the preparation of the mixture comprises: 
 adding the dispersing agent and the polishing particles to the deionized water and mixing them.    
     
     
         23 . The method as set forth in  claim 15 , wherein the milling of the mixture of the polishing particles, the deionized water, and the dispersing agent comprises: 
 additionally adding the dispersing agent at least one time.    
     
     
         24 . The method as set forth in  claim 23 , wherein the dispersing agent is added in an amount of 0.0001-10 wt % based on the polishing particles in such a way that the dispersing agent added in deionized water is an amount of 100-50% based on a total amount of dispersing agent, and that the dispersing agent added in the course of milling the mixture is an amount of 50% or less based on the total amount of dispersing agent.  
     
     
         25 . The method as set forth in  claim 15 , wherein the preparation of the polishing particles, the deionized water, and the dispersing agent comprises: 
 producing the polishing particles through a calcination process at a predetermined calcination temperature for a predetermined holding time.    
     
     
         26 . The method as set forth in  claim 25 , wherein the calcination temperature is 500-1000° C. in the production of the polishing particles.  
     
     
         27 . The method as set forth in  claim 25 , wherein the holding time is 10 min-10 hours at the calcination temperature in the production of the polishing particles.  
     
     
         28 . The method as set forth in  claim 25 , wherein the production of the polishing particles comprises: 
 preparing a crude precursor;    removing water of crystallization and adsorbed water;    removing a carbonate functional group; and    conducting recrystallization.    
     
     
         29 . The method as set forth in  claim 28 , wherein the crude precursor is cerium carbonate in the production of the polishing particles.  
     
     
         30 . The method as set forth in  claim 15 , further comprising: 
 adding an additive, including a weak acid or a weak base, to the mixture to control a pH of the slurry; and    conducting filtering to remove large particles, after the milling of the mixture of the polishing particles, the deionized water, and the dispersing agent.    
     
     
         31 . A method of polishing a predetermined substrate using the polishing slurry according to  claim 1.