Plating method and plating apparatus

Abstract

A plating method can fill a plated metal into interconnect recesses at a higher rate without forming voids in the plated metal embedded in the interconnect recesses. The plating method includes: preparing a substrate having interconnect recesses in a surface; carrying out first pretreatment of the substrate by immersing the substrate in a first pretreatment solution containing an accelerator, a metal ion and an acid; carrying out second pretreatment of the substrate by immersing the substrate in a second pretreatment solution containing an additive which inhibits the effect of the accelerator contained in the first pretreatment solution, and not containing an accelerator; and then carrying out electroplating of the substrate surface by using a plating solution containing at least a metal ion, an acid and a suppressor, and not containing an accelerator, thereby filling the plated metal into the interconnect recesses.

1 . A plating method comprising:
 preparing a substrate having interconnect recesses in a surface;   carrying out first pretreatment of the substrate by immersing the substrate in a first pretreatment solution containing an accelerator, a metal ion and an acid;   carrying out second pretreatment of the substrate by immersing the substrate in a second pretreatment solution containing an additive which inhibits the effect of the accelerator contained in the first pretreatment solution, and not containing an accelerator; and then   carrying out electroplating of the surface of the substrate by using a plating solution containing at least a metal ion, an acid and a suppressor, and not containing an accelerator, thereby filling the plated metal into the interconnect recesses.   
     
     
         2 . The plating method according to  claim 1 , wherein the first pretreatment is a preliminary electrolytic treatment carried out by electrolytically treating the surface of the substrate while immersing the substrate in the first pretreatment solution. 
     
     
         3 . The plating method according to  claim 2 , wherein the preliminary electrolytic treatment is carried out at a current density of 50 to 250 A/m 2 . 
     
     
         4 . The plating method according to  claim 1 , wherein a sulfur compound is used as the accelerator contained in the first pretreatment solution. 
     
     
         5 . The plating method according to  claim 4 , wherein the concentration of the accelerator contained in the first pretreatment solution is 5 to 500 μM/L. 
     
     
         6 . The plating method according to  claim 1 , wherein the additive contained in the second pretreatment solution and which inhibits the effect of the accelerator contained in the first pretreatment solution is a leveler. 
     
     
         7 . The plating method according to  claim 6 , wherein the leveler is an ethyleneimine polymer or a derivative thereof. 
     
     
         8 . The plating method according to  claim 1 , wherein at least one of the first pretreatment, the second pretreatment and the electroplating is carried out while stirring the treatment solution. 
     
     
         9 . The plating method according to  claim 1 , wherein the second pretreatment is carried out while stirring the second pretreatment solution, and the electroplating is carried out while stirring the plating solution with a stirring intensity equal to or higher than the stirring intensity in the second pretreatment. 
     
     
         10 . The plating method according to  claim 1 , wherein the surface of the substrate is cleaned with dilute sulfuric acid after the first pretreatment, and the surface of the substrate is cleaned with dilute sulfuric acid after the second pretreatment. 
     
     
         11 . A plating apparatus for carrying out plating of a surface of a substrate having interconnect recesses in the surface, the plating apparatus comprising:
 a first pretreatment unit for carrying out first pretreatment of the substrate by immersing the substrate in a first pretreatment solution containing an accelerator, a metal ion and an acid;   a second pretreatment unit for carrying out second pretreatment of the substrate by immersing the substrate in a second pretreatment solution containing an additive which inhibits the effect of the accelerator contained in the first pretreatment solution, and not containing an accelerator; and   a plating unit for carrying out electroplating of the surface of the substrate after the second pretreatment by using a plating solution containing at least a metal ion, an acid and a suppressor, and not containing an accelerator, thereby filling the plated metal into the interconnect recesses.   
     
     
         12 . The plating apparatus according to  claim 11 , wherein the first pretreatment unit is configured to carry out an electrolytic treatment of the surface of the substrate while immersing the substrate in the first pretreatment solution. 
     
     
         13 . The plating apparatus according to  claim 11 , further comprising a first cleaning unit for cleaning with dilute sulfuric acid the surface of the substrate which has undergone the first pretreatment in the first pretreatment unit, and a second cleaning unit for cleaning with dilute sulfuric acid the surface of the substrate which has undergone the second pretreatment in the second pretreatment unit. 
     
     
         14 . The plating apparatus according to  claim 11 , wherein at least one of the first pretreatment unit, the second pretreatment unit and the plating unit is provided with a stirring device for stirring the treatment solution, and wherein the plating apparatus includes a control section for controlling the stirring speed of the stirring device, the first pretreatment time in the first pretreatment unit, the second pretreatment time in the second pretreatment unit, and the electroplating time in the plating unit. 
     
     
         15 . The plating apparatus according to  claim 14 , wherein the second pretreatment unit is provided with a stirring device for stirring the second treatment solution; and the control section, based on the width or diameter and the depth of the interconnect recesses, determines the substrate immersion time in the second pretreatment and the stirring intensity of the second pretreatment solution.