Polishing liquid and polishing method

Abstract

A method for chemical mechanical polishing of a body to be polished in a planarization process for manufacturing of a semiconductor integrated circuit. The body to be polished including at least a first layer containing polysilicon or modified polysilicon and a second layer containing at least one selected from the group consisting of silicon oxide, silicon nitride, silicon carbide, silicon carbonitride, silicon oxycarbide, and silicon oxynitride. The method including supplying a polishing liquid to a polishing pad on a polishing platen, rotating the polishing platen, and thereby causing relative motion of the polishing pad and a surface to be polished of the body to be polished while in contact with each other for carrying out selective polishing of the second layer with respect to the first layer, and the polishing liquid including a colloidal silica particles, an organic acid, and an anionic surfactant.

What is claimed is: 
     
         1 . A method for chemical mechanical polishing of a body to be polished in a planarization process for manufacturing of a semiconductor integrated circuit, the body to be polished comprising at least a first layer containing polysilicon or modified polysilicon and a second layer containing at least one selected from the group consisting of silicon oxide, silicon nitride, silicon carbide, silicon carbonitride, silicon oxycarbide, and silicon oxynitride,
 the method comprising supplying a polishing liquid to a polishing pad on a polishing platen, rotating the polishing platen, and thereby causing relative motion of the polishing pad and a surface to be polished of the body to be polished while in contact with each other for carrying out selective polishing of the second layer with respect to the first layer, and   the polishing liquid having a pH of 1.5 to 7.0, and comprising (1) colloidal silica particles, (2) an organic acid, and (3) an anionic surfactant.   
     
     
         2 . The method according to  claim 1 , wherein the body to be polished is polished at a ratio represented by RR(second layer)/RR(first layer) in the range of 1.5 to 200 wherein RR(first layer) represents a polishing rate of the first layer and RR(second layer) represents a polishing rate of the second layer. 
     
     
         3 . The method according to  claim 1 , wherein the concentration of the colloidal silica is 0.1% by mass to 10% by mass based on the total mass of the polishing liquid. 
     
     
         4 . The method according to  claim 1 , wherein the colloidal silica has an average primary particle diameter of 5 nm to 100 nm and an average secondary particle diameter of 10 nm to 300 nm. 
     
     
         5 . The method according to  claim 1 , wherein the organic acid contains at least one carboxyl group in a molecule structure thereof. 
     
     
         6 . The method according to  claim 1 , wherein the organic acid is represented by the following Formula (I),
   HOOC—R—COOH   (I)
   
       wherein R represents an alkylene group having 1 to 20 carbon atoms, an alkynylene group, a cycloalkylene group, an arylene group, or a group obtained by combining two or more thereof. 
     
     
         7 . The method according to  claim 1 , wherein the concentration of the organic acid is 0.001% by mass to 3% by mass based on the total mass of the polishing liquid. 
     
     
         8 . The method according to  claim 1 , wherein the anionic surfactant is at least one compound selected from the group consisting of compounds represented by the following Formulae (II), (III), (IV), and (V),
   R 1 —O—SO 3 X   Formula (II)
   
       wherein in Formula (II), R 1  represents an alkyl group having 6 to 30 carbon atoms, an alkenyl group, a cycloalkyl group, an aryl group, an aralkyl group, or a group obtained by combining two or more thereof, and X represents a hydrogen atom, sodium, potassium, ammonium, diethanolamine, or triethanolamine,
   R 2 —O—(CH 2 CH 2 O) n —SO 3 X   Formula (III)
 
 
       wherein in Formula (III), R 2  represents an alkyl group having 6 to 30 carbon atoms, an alkenyl group, a cycloalkyl group, an aryl group, an aralkyl group, or a group obtained by combining two or more thereof, n represents an integer of 1 to 10, and X represents a hydrogen atom, sodium, potassium, ammonium, diethanolamine, or triethanolamine, 
       
         
           
           
               
               
           
         
       
       wherein in Formula (IV), R 3  represents an alkyl group having 6 to 30 carbon atoms, an alkenyl group, a cycloalkyl group, an aryl group, an aralkyl group, or a group obtained by combining two or more thereof, X represents a hydrogen atom, sodium, potassium, ammonium, diethanolamine, or triethanolamine, and a plurality of Xs may be the same or different from each other, and 
       
         
           
           
               
               
           
         
       
       wherein in Formula (V), R 4  represents an alkylene group having 1 to 20 carbon atoms, an alkynylene group, a cycloalkylene group, an arylene group, an alkylene oxide group, or a group obtained by combining two or more thereof, R 5  to R 9  each independently represent a hydrogen atom, a hydroxy group, an alkyl group having 1 to 30 carbon atoms, an alkenyl group, a cycloalkyl group, an aryl group, an aralkyl group, a sulfo group, a carboxyl group, or a hydrocarbon group containing any of these groups, and X represents a hydrogen atom, sodium, potassium, ammonium, diethanolamine, or triethanolamine. 
     
     
         9 . The method according to  claim 1 , wherein the concentration of the anionic surfactant is 0.001% by mass to 1% by mass based on the total mass of the polishing liquid. 
     
     
         10 . The method according to  claim 1 , wherein the organic acid is a nonpolymeric organic acid. 
     
     
         11 . The method according to  claim 1 , wherein the colloidal silica particles do not contain impurities in the particles and are obtained by hydrolysis of alkoxysilane. 
     
     
         12 . The method according to  claim 1 , wherein all the abrasive grains contained in the polishing liquid are the colloidal silica particles. 
     
     
         13 . The method according to  claim 1 , wherein the second layer contains at least silicon nitride. 
     
     
         14 . A method for producing a gate electrode in a semiconductor integrated circuit, the method comprising forming the gate electrode by the method according to  claim 1 .