Plating apparatus and plating solution management method

Abstract

A plating apparatus plates a substrate with Sn alloy to form an Sn alloy film on a surface of the substrate. The apparatus includes: a plating bath for retaining a plating solution therein, the substrate being immersed in the plating solution in a position opposite to an insoluble anode; a plating solution dialysis line for extracting the plating solution from the plating bath and returning the plating solution to the plating bath; a dialysis cell provided in the plating solution dialysis line and configured to remove a free acid from the plating solution by dialysis using an anion exchange membrane; a free acid concentration analyzer; and a controller for controlling a flow rate of the plating solution flowing through the plating solution dialysis line based on the concentration of the free acid measured by the free acid concentration analyzer.

What is claimed is: 
     
         1 . A plating apparatus for plating a substrate with Sn alloy to form an Sn alloy film on a surface of the substrate, comprising:
 a plating bath for retaining a plating solution therein and having an insoluble anode disposed in the plating solution, the substrate being immersed in the plating solution in a position opposite to the insoluble anode;   a plating solution dialysis line for extracting the plating solution from the plating bath and returning the plating solution to the plating bath;   a dialysis cell provided in the plating solution dialysis line and configured to remove a free acid from the plating solution by dialysis using an anion exchange membrane;   a free acid concentration analyzer configured to measure a concentration of the free acid in the plating solution; and   a controller for controlling a flow rate of the plating solution flowing through the plating solution dialysis line, based on the concentration of the free acid measured by the free acid concentration analyzer.   
     
     
         2 . The plating apparatus according to  claim 1 , further comprising:
 a plating solution circulation line for extracting the plating solution from the plating bath and returning the plating solution to the plating bath during plating of the substrate, the plating solution dialysis line being coupled to the plating solution circulation line.   
     
     
         3 . The plating apparatus according to  claim 1 , wherein the controller is configured to control the flow rate of the plating solution flowing through the plating solution dialysis line such that the concentration of the free acid in the plating solution lies in a range of 60 to 250 g/L. 
     
     
         4 . The plating apparatus according to  claim 1 , wherein the plating solution dialysis line is provided with a plating solution flow control mechanism located between the plating bath and the dialysis cell, and the controller is configured to control the plating solution flow control mechanism such that a coefficient lies in a range of 0.3 to 0.7, the coefficient being determined by dividing an effective area (m 2 ) of the anion exchange membrane by the flow rate (L/h) of the plating solution. 
     
     
         5 . The plating apparatus according to  claim 4 , further comprising:
 a water supply line coupled to the dialysis cell and provided with a water flow control mechanism,   wherein the controller is configured to control the water flow control mechanism such that a flow rate of water, supplied through the water supply line into the dialysis cell, is 30% to 100% of the flow rate of the plating solution supplied through the plating solution dialysis line into the dialysis cell.   
     
     
         6 . A plating apparatus for plating a substrate with Sn alloy to form an Sn alloy film on a surface of the substrate, comprising:
 a plating bath for retaining a plating solution therein and having an insoluble anode disposed in the plating solution, the substrate being immersed in the plating solution in a position opposite to the insoluble anode;   a plating solution dialysis line for extracting the plating solution from the plating bath and returning the plating solution to the plating bath;   a dialysis cell provided in the plating solution dialysis line and configured to remove a free acid from the plating solution by dialysis using an anion exchange membrane; and   a controller for controlling a flow rate of the plating solution flowing through the plating solution dialysis line, based on an integrated value of a quantity of electricity applied to the plating solution in the plating bath.   
     
     
         7 . The plating apparatus according to  claim 6 , further comprising:
 a plating solution circulation line for extracting the plating solution from the plating bath and returning the plating solution to the plating bath during plating of the substrate, the plating solution dialysis line being coupled to the plating solution circulation line.   
     
     
         8 . The plating apparatus according to  claim 6 , wherein the controller is configured to control the flow rate of the plating solution flowing through the plating solution dialysis line such that a concentration of the free acid in the plating solution lies in a range of 60 to 250 g/L. 
     
     
         9 . The plating apparatus according to  claim 6 , wherein the plating solution dialysis line is provided with a plating solution flow control mechanism located between the plating bath and the dialysis cell, and the controller is configured to control the plating solution flow control mechanism such that a coefficient lies in a range of 0.3 to 0.7, the coefficient being determined by dividing an effective area (m 2 ) of the anion exchange membrane by the flow rate (L/h) of the plating solution. 
     
     
         10 . The plating apparatus according to  claim 9 , further comprising:
 a water supply line coupled to the dialysis cell and provided with a water flow control mechanism,   wherein the controller is configured to control the water flow control mechanism such that a flow rate of water, supplied through the water supply line into the dialysis cell, is 30% to 100% of the flow rate of the plating solution supplied through the plating solution dialysis line into the dialysis cell.   
     
     
         11 . A plating solution management method comprising:
 forming an Sn alloy film on a surface of a substrate by applying a voltage between an insoluble anode and the substrate disposed opposite to each other in a plating solution retained in a plating bath;   measuring a concentration of a free acid in the plating solution by a free acid concentration analyzer;   extracting the plating solution from the plating bath through a plating solution dialysis line and then returning the plating solution to the plating bath; and   removing the free acid from the plating solution flowing through the plating solution dialysis line by a dialysis cell having an anion exchange membrane, while controlling a flow rate of the plating solution flowing through the plating solution dialysis line based on the concentration of the free acid measured by the free acid concentration analyzer.   
     
     
         12 . The plating solution management method according to  claim 11 , wherein the flow rate of the plating solution flowing through the plating solution dialysis line is controlled such that the concentration of the free acid in the plating solution lies in a range of 60 to 250 g/L. 
     
     
         13 . The plating solution management method according to  claim 11 , wherein the plating solution dialysis line is provided with a plating solution flow control mechanism located between the plating bath and the dialysis cell, and the plating solution flow control mechanism is controlled such that a coefficient lies in a range of 0.3 to 0.7, the coefficient being determined by dividing an effective area (m 2 ) of the anion exchange membrane by the flow rate (L/h) of the plating solution. 
     
     
         14 . The plating solution management method according to  claim 13 , wherein a water supply line provided with a water flow control mechanism is coupled to the dialysis cell, and the water flow control mechanism is controlled such that a flow rate of water, supplied through the water supply line into the dialysis cell, is 30% to 100% of the flow rate of the plating solution supplied through the plating solution dialysis line into the dialysis cell. 
     
     
         15 . A plating solution management method comprising:
 forming an Sn alloy film on a surface of a substrate by applying a voltage between an insoluble anode and the substrate disposed opposite to each other in a plating solution retained in a plating bath;   extracting the plating solution from the plating bath through a plating solution dialysis line and then returning the plating solution to the plating bath; and   removing a free acid from the plating solution flowing through the plating solution dialysis line by a dialysis cell having an anion exchange membrane, while controlling a flow rate of the plating solution flowing through the plating solution dialysis line based on an integrated value of a quantity of electricity applied to the plating solution in the plating bath.   
     
     
         16 . The plating solution management method according to  claim 15 , wherein the flow rate of the plating solution flowing through the plating solution dialysis line is controlled such that a concentration of the free acid in the plating solution lies in a range of 60 to 250 g/L. 
     
     
         17 . The plating solution management method according to  claim 15 , wherein the plating solution dialysis line is provided with a plating solution flow control mechanism located between the plating bath and the dialysis cell, and the plating solution flow control mechanism is controlled such that a coefficient lies in a range of 0.3 to 0.7, the coefficient being determined by dividing an effective area (m 2 ) of the anion exchange membrane by the flow rate (L/h) of the plating solution. 
     
     
         18 . The plating solution management method according to  claim 17 , wherein a water supply line provided with a water flow control mechanism is coupled to the dialysis cell, and the water flow control mechanism is controlled such that a flow rate of water, supplied through the water supply line into the dialysis cell, is 30% to 100% of the flow rate of the plating solution supplied through the plating solution dialysis line into the dialysis cell.