Copper Plating Bath and Plating Method

Abstract

An acid copper plating solution and plating method are disclosed. The acid copper plating solution comprises copper ions, an organic acid or an inorganic acid, chloride ions, high molecular weight surfactant which controls the electrodeposition reaction, and a sulfur-containing saturated organic compound which promotes the electrocoating rate, wherein the high molecular weight surfactant comprises two or more types with different hydrophobicities. The plating method is a method for forming a plating film on a conductor layer, which is formed on at least a part of a structural object having a concave-convex pattern on a semiconductor substrate, and comprises providing a cathode potential to the conductor layer and supplying a plating solution which electrically connects an anode with the conductor layer, wherein the plating solution contains 25-75 g/l of copper ion and 0.4 mol/l of an organic acid or inorganic acid and an electric resistor is installed between the conductor layer and the anode. Also disclosed is a plating method for forming a wiring circuit on an electronic circuit substrate having fine holes and trenches, comprising forming a plating film on a conductor layer, which is formed on at least a part of the substrate, and filling the holes and trenches with copper, wherein the plating film is formed by using an acid copper plating solution containing copper ions, organic or inorganic acid, chloride ions, sulfur-containing saturated organic compound, and high molecular weight surfactant controlling electrocoating concentration of 500 ppm or more. The acid copper plating solution and the plating methods are extremely useful as a technology for plating the surface of wafers, which are semiconductor materials, particularly for forming circuit patterns having submicron-level trenches on electronic circuit substrates such as wafers, semi-conductor substrates, or printed boards by using metal plating such as copper plating and can therefore be used with advantage for manufacturing next generation electronic circuit boards with an increasing density of wiring circuits.

1 . An acid copper plating solution comprising copper ions, an organic acid or an inorganic acid, chloride ions, high molecular weight surfactant which controls the electrodeposition reaction, and a sulfur-containing saturated organic compound which promotes the electrocoating rate, wherein the high molecular weight surfactant comprises at least two types with different hydrophobicities. 
     
     
         2 . The acid copper plating solution according to  claim 1 , wherein all of the at least two types of high molecular weight surfactants with different hydrophobicities are nonionic surfactants and the concentration of a surfactant having comparatively strong hydrophobicity is less than the concentration of a surfactant having comparatively weak hydrophobicity. 
     
     
         3 . The acid copper plating solution according to  claim 1 , wherein among the at least two types of high molecular weight surfactants with different hydrophobicities, the concentration of a nonionic surfactant having comparatively strong hydrophobicity is equal to or less than the critical micelle concentration in the acid copper plating solution. 
     
     
         4 . The acid copper plating solution according to  claim 1 , wherein among the at least two types of high molecular weight surfactants with different hydrophobicities, the concentration of a nonionic surfactant having comparatively weak hydrophobicity is equal to or more than the critical micelle concentration in the acid copper plating solution. 
     
     
         5 . The acid copper plating solution according to  claim 1 , wherein among the at least two types of high molecular weight surfactants with different hydrophobicities, the concentration of a nonionic surfactant having comparatively strong hydrophobicity is equal to or less than the critical micelle concentration in the acid copper plating solution and the concentration of a nonionic surfactant having comparatively weak hydrophobicity is equal to or more than the critical micelle concentration in the acid copper plating solution. 
     
     
         6 . The acid copper plating solution according to  claim 1 , wherein the at least two types of high molecular weight surfactants with different hydrophobicities comprise a nonionic surfactant and a surfactant other than the nonionic surfactant, and the concentration of the nonionic surfactant is higher than the concentration of the surfactant other than the nonionic surfactant. 
     
     
         7 . The acid copper plating solution according to  claim 1 , wherein the at least two types of high molecular weight surfactants with different hydrophobicities comprise a nonionic surfactant and a surfactant other than the nonionic surfactant, and the surfactant other than the nonionic surfactant is a cationic surfactant, a surfactant which is nonionic but exhibits cationic properties under strong acidic conditions, or an amphoteric surfactant. 
     
     
         8 . The acid copper plating solution according to  claim 1 , wherein the at least two types of high molecular weight surfactants with different hydrophobicities comprise a nonionic surfactant and a surfactant other than the nonionic surfactant, and the concentration of the surfactant other than the nonionic surfactant is equal to or lower than the critical micelle concentration. 
     
     
         9 . The acid copper plating solution according to  claim 1 , wherein the at least two types of high molecular weight surfactants with different hydrophobicities comprise a nonionic surfactant and a surfactant other than the nonionic surfactant, and the concentration of the nonionic surfactant is equal to or higher than the critical micelle concentration. 
     
     
         10 . The acid copper plating solution according to  claim 1 , wherein the at least two types of high molecular weight surfactants with different hydrophobicities comprise a nonionic surfactant and a surfactant other than the nonionic surfactant, and the concentration of the nonionic surfactant is equal to or higher than the critical micelle concentration and the concentration of the surfactant other than the nonionic surfactant is equal to or lower than the critical micelle concentration. 
     
     
         11 . An electrolytic plating method comprising performing plating at a cathode current density in the range of 0.1-30 mA/cm 2  using the acid copper plating solution of  claim 1 .