Apparatus for electrochemical deposition of a metal

Abstract

The invention as described in the following relates to an apparatus for the electrochemical deposition of a metal on a substrate, which apparatus is capable of refreshing an electrolyte used for the deposition in a continuous way. Furthermore, the invention as described relates to a method of refreshing an electrolyte for the electrochemical deposition of a metal on a substrate.

1 . An apparatus for the electrochemical deposition of a metal on a substrate, the apparatus comprising:
 a plating tank holding a plating electrolyte and a refreshing tank in fluidic connection to the plating tank for refreshing the plating electrolyte,   wherein the plating tank comprises an inert electrode electrically connected to the substrate by a rectifier, and   wherein the refreshing tank comprises a first compartment and a second compartment, and the compartments are separated from each other by a semi permeable separator,   wherein the first compartment comprises at least one soluble anode of a metal to be deposited on the substrate and the second compartment comprises at least one inert electrode, the inert electrode and the soluble anode are electrically connected to a rectifier and   wherein the at least one soluble anode is at least during the operation of the apparatus in a liquid state .   
     
     
         2 . The apparatus according to  claim 1 , wherein the electrical conductivity between the electrolyte in the plating tank and electrolyte in the refreshing tank is ≦1*10 −4  S. 
     
     
         3 . The apparatus according to  claim 1 , wherein the refreshing tank comprises at least two soluble anodes of two different metals to be deposited on the substrate, and each of the soluble anodes is connected to a separate rectifier. 
     
     
         4 . The apparatus according to  claim 3 , wherein the refreshing tank comprises a separate inert electrode per rectifier. 
     
     
         5 . (canceled) 
     
     
         6 . The apparatus according to  claim 1 , wherein the refreshing tank comprises a kettle for holding the soluble anode, said kettle comprising an electrical contact for contacting the soluble anode. 
     
     
         7 . The apparatus according to  claim 1 , wherein the second compartment holds an electrolyte which is different from the plating electrolyte. 
     
     
         8 . The apparatus according to  claim 1 , wherein the semi permeable separator is at least one of a membrane, a diaphragm, and a micro-porous wall. 
     
     
         9 . The apparatus according to  claim 1 , wherein the electrode of the plating tank comprises at least an electrode base body and a screen, said screen reducing the exchange of liquid in the direct environment of the electrode. 
     
     
         10 . The apparatus according to  claim 1 , wherein the apparatus comprises a drop section for electrically isolating the electrolyte in the plating tank from the electrolyte in the refreshing tank. 
     
     
         11 . The apparatus according to  claim 1 , said apparatus comprising an analyzer for analyzing the concentration in the electrolyte of the metal to be deposited on the substrate. 
     
     
         12 . A method of refreshing an electrolyte for electrochemical deposition of a metal on a substrate, the method comprising the steps of:
 separating at least a partial stream of the electrolyte from a plating tank and feeding said stream to a refreshing tank, said refreshing tank comprising a first compartment and a second compartment, the compartments are separated from each other by a semi permeable separator, wherein the first compartment comprising at least one soluble anode of a metal to be deposited on the substrate and the second compartment comprises at least one inert electrode;   connecting the inert electrode and the soluble anode electrically to a rectifier;   setting the current and/or voltage of the rectifier to a range suitable to electrochemically dissolve metal from the soluble anode;   re-feeding at least a partial stream of the electrolyte in the refreshing tank to the plating tank.   
     
     
         13 . The method according to  claim 12 , wherein the concentration in the electrolyte of the ions of the metal to be deposited is analyzed and the current and/or voltage of the rectifier is set to maintain a concentration of the metal to be deposited within a variation limit of ≦3% by weight. 
     
     
         14 . Use of an apparatus according to any one of the  claims 1  to  11  for the electrochemical deposition of a metal form an alkaline electrolyte. 
     
     
         15 . The use according to  claim 14 , wherein the metal to be deposited is a metal of the group consisting of gallium, indium, and thallium. 
     
     
         16 . The apparatus according to  claim 1 , wherein the electrical conductivity between the electrolyte in the plating tank and electrolyte in the refreshing tank is ≦1*10 −5  S. 
     
     
         17 . The apparatus according to  claim 1 , wherein the electrical conductivity between the electrolyte in the plating tank and electrolyte in the refreshing tank is ≦1*10 −6  S. 
     
     
         18 . The apparatus according to  claim 1 , wherein:
 the refreshing tank comprises at least two soluble anodes of two different metals to be deposited on the substrate, and each of the soluble anodes is connected to a separate rectifier,   refreshing tank comprises a separate inert electrode per rectifier,   the refreshing tank comprises a kettle for holding the soluble anode, said kettle comprising an electrical contact for contacting the soluble anode,   the second compartment holds an electrolyte which is different from the plating electrolyte,   the semi permeable separator is at least one of a membrane, a diaphragm, and a micro-porous wall,   the apparatus comprises a drop section for electrically isolating the electrolyte in the plating tank from the electrolyte in the refreshing tank, and   the apparatus comprises an analyzer for analyzing the concentration in the electrolyte of the metal to be deposited on the substrate.