Plating apparatus and method for controlling plating solution

Abstract

A plating apparatus can keep concentrations of components of a plating solution constant over a long period of time and can stably form a plated film having a more uniform thickness on a surface of a substrate while minimizing an amount of the plating solution used. The plating apparatus includes a plating cell for carrying out electroplating of a surface of a substrate with a space between the surface of the substrate, serving as a cathode, and an insoluble anode filled with a plating solution, a plating solution circulation system for supplying the plating solution to the plating cell and recovering the plating solution in a circulatory manner, and a plating solution component replenishment system for supplying a replenisher solution, containing a component of the plating solution in a higher concentration than that in the plating solution, to the plating solution which circulates in the plating solution circulation system, thereby maintaining the concentration of the component in the plating solution within a predetermined range.

1 . A plating apparatus comprising: 
 a plating cell for carrying out electroplating of a surface of a substrate with a space between the surface of the substrate, serving as a cathode, and an insoluble anode filled with a plating solution;    a plating solution circulation system for supplying the plating solution to the plating cell and recovering the plating solution in a circulatory manner; and    a plating solution component replenishment system for supplying a replenisher solution, containing a component of the plating solution in a higher concentration than that in the plating solution, to the plating solution which circulates in the plating solution circulation system, thereby maintaining the concentration of the component in the plating solution within a predetermined range.    
   
   
       2 . The plating apparatus according to  claim 1 , further comprising a plating solution discharge system for discharging a predetermined amount of the plating solution from the plating solution circulation system.  
   
   
       3 . The plating apparatus according to  claim 1 , wherein the plating solution circulation system includes a plating solution buffer tank for recovering the plating solution after its use in plating in the plating cell, a plating solution adjustment tank, connected to the plating solution buffer tank, for replenishing the plating solution with the replenisher solution, and a plating solution supply tank, connected to the plating solution adjustment tank, for storing the plating solution which has been adjusted in the plating solution adjustment tank and supplying the plating solution to the plating cell.  
   
   
       4 . The plating apparatus according to  claim 1 , wherein the component contained in the replenisher solution, supplied to the plating solution by the plating solution component replenishment system, comprises an organic additive comprising at least one of a reaction accelerator, a reaction suppressor and a leveler, a metal ion, a supporting electrolyte and a halogen ion.  
   
   
       5 . The plating apparatus according to  claim 1 , wherein the replenishment quantity of the replenisher solution is determined based on a cumulative quantity of electricity taken for electroplating.  
   
   
       6 . The plating apparatus according to  claim 1 , wherein the replenisher solution contains one component of the plating solution in a higher concentration than that in the plating solution, and is supplied to the plating solution from a replenisher solution tank.  
   
   
       7 . The plating apparatus according to  claim 1 , wherein the plating cell has a high-resistance structure disposed between the insoluble anode and the substrate which serves as a cathode.  
   
   
       8 . The plating apparatus according to  claim 1 , wherein the replenishment quantity of the replenisher solution is determined by using a consumption coefficient determined by the current density of electric current applied to carry out plating in the plating cell and by the time of application of the electric current.  
   
   
       9 . The plating apparatus according to  claim 8 , wherein the plating cell is divided into an anode chamber and a cathode side area by the high-resistance structure disposed between the insoluble anode and the substrate which serves as a cathode, and the replenishment quantity of the replenisher solution is determined individually for the anode chamber and for the cathode side area, and the respective values obtained are summed up.  
   
   
       10 . The plating apparatus according to  claim 8 , wherein the component of the plating solution, contained in the replenisher solution whose replenishment quantity is determined by using the consumption coefficient determined by the current density and the time of application of the electric current, is a reaction accelerator.  
   
   
       11 . The plating apparatus according to  claim 3 , wherein the plating solution adjustment tank has a liquid level sensor for measuring a liquid level of the plating solution in the plating solution adjustment tank.  
   
   
       12 . The plating apparatus according to  claim 1 , further comprising a plating solution analyzer for sampling the plating solution to be supplied to the plating cell, and analyzing the concentrations of the components of the plating solution.  
   
   
       13 . A method for controlling a plating solution, comprising: 
 replenishing a plating solution, to be used in plating, with a replenisher solution containing a component of the plating solution in a higher concentration than that in the plating solution, thereby maintaining the concentration of the component in the plating solution within a predetermined range.    
   
   
       14 . The method for controlling a plating solution according to  claim 13 , wherein the replenishment quantity of the replenisher solution is determined based on a cumulative quantity of electricity taken for electroplating.  
   
   
       15 . The method for controlling a plating solution according to  claim 13 , wherein the replenishment quantity of the replenisher solution is determined by using a consumption coefficient determined by the current density of electric current applied to carry out plating in the plating cell and by the time of application of the electric current.  
   
   
       16 . The method, for controlling a plating solution according to  claim 15 , wherein the plating cell is divided into an anode chamber and a cathode side area by a high-resistance structure disposed between an insoluble anode and a substrate which serves as a cathode, and the replenishment quantity of the replenisher solution is determined individually for the anode chamber and for the cathode side area, and the respective values obtained are summed up.  
   
   
       17 . The method for controlling a plating solution according to  claim 15 , where in the replenishment quantity of the replenisher solution is determined based on a cumulative quantity of electricity taken for electroplating.  
   
   
       18 . The method for controlling a plating solution according to  claim 13 , wherein a plating metal is copper, and the plating solution having a copper ion concentration of 20-60 g/L is replenished with an aqueous solution of copper sulfate having a copper sulfate concentration of 200 g/L to saturation concentration, thereby maintaining the concentration of copper ion in the plating solution within a predetermined range.  
   
   
       19 . The method for controlling a plating solution according to  claim 13 , wherein the plating solution contains sulfuric acid as a supporting electrolyte, and the plating solution having a sulfuric acid concentration of 10-100 g/L is replenished with sulfuric acid having a concentration of 20-98 wt %, thereby maintaining the concentration of sulfuric acid in the plating solution within a predetermined range.  
   
   
       20 . The method for controlling a plating solution according to  claim 13 , wherein the plating solution contains chlorine as a halogen ion, and the plating solution having a chlorine concentration of 30-90 mg/L is replenished with hydrochloric acid having a concentration of 1-36 wt %, thereby maintaining the concentration of chlorine in the plating solution within a predetermined range.  
   
   
       21 . A method for controlling a plating solution, comprising: 
 recovering a plating solution, which has been used in plating in a plating cell, in a plating solution buffer tank;    sending the plating solution in the plating solution buffer tank to a plating solution adjustment tank, and replenishing the plating solution in the plating solution adjustment tank with a replenisher solution containing a component of the plating solution in a higher concentration than that in the plating solution, thereby maintaining the concentration of the component in the plating solution within a predetermined range;    sending the plating solution in the plating solution adjustment tank to a plating solution supply tank; and    supplying the plating solution in the plating solution supply tank to the plating cell.    
   
   
       22 . The method for controlling a plating solution according to  claim 21 , where in the replenishment quantity of the replenisher solution is determined based on a cumulative quantity of electricity taken for electroplating.  
   
   
       23 . The method for controlling a plating solution according to  claim 21 , where in the replenishment quantity of the replenisher solution is determined by using a consumption coefficient determined by the current density of electric current applied to carry out plating in the plating cell and by the time of application of the electric current.  
   
   
       24 . The method for controlling a plating solution according to  claim 23 , wherein the plating cell is divided into an anode chamber and a cathode side area by a high-resistance structure disposed between an insoluble anode and a substrate which serves as a cathode, and the replenishment quantity of the replenisher solution is determined individually for the anode chamber and for the cathode side area, and the respective values obtained are summed up.  
   
   
       25 . The method for controlling a plating solution according to  claim 23 , wherein the component of the plating solution, contained in the replenisher solution whose replenishment quantity is determined by using the consumption coefficient determined by the current density and the time of application of the electric current, is a reaction accelerator.  
   
   
       26 . The method for controlling a plating solution according to  claim 21 , wherein a plating metal is copper, and the plating solution having a copper ion concentration of 20-60 g/L is replenished with an aqueous solution of copper sulfate having a copper sulfate concentration of 200 g/L to saturation concentration, thereby maintaining the concentration of copper ion in the plating solution within a predetermined range.  
   
   
       27 . The method for controlling a plating solution according to  claim 21 , wherein the plating solution contains sulfuric acid as a supporting electrolyte, and the plating solution having a sulfuric acid concentration of 10-100 g/L is replenished with sulfuric acid having a concentration of 20-98 wt %, thereby maintaining the concentration of sulfuric acid in the plating solution within a predetermined range.  
   
   
       28 . The method for controlling a plating solution according to  claim 21 , wherein the plating solution contains chlorine as a halogen ion, and the plating solution having a chlorine concentration of 30-90 mg/L is replenished with hydrochloric acid having a concentration of 1-36 wt %, thereby maintaining the concentration of chlorine in the plating solution within a predetermined range.