Apparatus and methods for chemical electrodeposition on a substrate for solar cell fabrication

Abstract

The invention relates generally to electrodeposition apparatus and methods. The invention finds particular use in fabricating thin film solar cells. Electrodeposition is improved by using a continuous thin film flow of electrodeposition solution between a substrate and a counter electrode, positioned in close proximity to each other, while the plating current is applied. Apparatus for carrying out methods described herein are highlighted particularly by flow manifolds that allow electrodeposition in the manner described.

1 . An electrodeposition apparatus, comprising:
 (i) a movement assembly for positioning a substrate in close proximity to a counter electrode during electrodeposition; and   (ii) a flow manifold configured to flow an electrolyte between the substrate and a counter electrode and continuously supply electrolyte between the plating surface of the substrate and the counter electrode;   
       wherein the counter electrode is positioned on, or an integral component of, the flow manifold. 
     
     
         2 . The apparatus of  claim 1 , wherein the movement assembly is configured to move a continuous sheet type substrate, said continuous sheet type substrate comprising at least one of an electrically conductive material and a material having an electrically conductive coating. 
     
     
         3 . The apparatus of  claim 2 , wherein the movement assembly comprises a drive component configured to move the continuous sheet type substrate past the flow manifold and counter electrode during electrodeposition without substantially bending the substrate. 
     
     
         4 . The apparatus of  claim 3 , wherein the counter electrode is configured to substantially span the width of the continuous sheet type substrate as the continuous sheet type substrate passes by the counter electrode during electrodeposition. 
     
     
         5 . The apparatus of  claim 4 , wherein the counter electrode comprises a substantially planar surface that is positioned substantially parallel to the surface of the substrate during electrodeposition. 
     
     
         6 . The apparatus of  claim 5 , wherein the counter electrode and the substrate are between about 2 mm and about 10 mm apart during electrodeposition. 
     
     
         7 . The apparatus of  claim 6 , wherein the flow manifold is configured to produce a substantially laminar flow or a turbulent flow of the electrolyte between the substrate and the counter electrode. 
     
     
         8 . The apparatus of  claim 7 , further comprising one or more seals, said seals configured to channel the flow of electrolyte in order to maximize contact with the substrate and minimize the amount of electrolyte needed to produce the continuous supply of electrolyte contacting the substrate during electrodeposition. 
     
     
         9 . The apparatus of  claim 8 , further comprising one or more overflow channels for collecting used electrolyte. 
     
     
         10 . The apparatus of  claim 8 , wherein the one or more seals are configured to form a chamber between the substrate and the flow manifold when the flow manifold and the substrate are engaged with, or in close proximity to, said one or more seals; said flow manifold further comprising an electrolyte inlet and an electrolyte outlet, each contained within the chamber during electrodeposition. 
     
     
         11 . The apparatus of  claim 10 , wherein the one or more seals comprise a perimeter-type seal. 
     
     
         12 . An electrodeposition method comprising:
 (i) flowing an electrolyte between a substrate and a counter electrode using a flow manifold that supplies a continuous supply of electrolyte to the substrate while the plating surface of said substrate is in close proximity to the counter electrode; and   (ii) applying a plating potential between the substrate and the counter electrode;   
       wherein the counter electrode is configured to substantially span at least one dimension of the substrate and is positioned on, or an integral component of, the flow manifold. 
     
     
         13 . The method of  claim 12 , further comprising moving the substrate continuously past the counter electrode during electrodeposition, wherein the substrate comprises a continuous sheet, said continuous sheet comprising at least one of an electrically conductive material and a material having an electrically conductive coating. 
     
     
         14 . The method of  claim 13 , wherein the counter electrode and the substrate are positioned between about 2 mm and about 10 mm apart during electrodeposition. 
     
     
         15 . The method of  claim 14 , wherein flowing an electrolyte between the substrate and the counter electrode comprises producing a substantially laminar flow or a turbulent flow of the electrolyte between the substrate and the counter electrode. 
     
     
         16 . The method of  claim 15 , further comprising employing one or more seals, said seals configured to channel the flow of electrolyte in order to maximize contact with the substrate and minimize the amount of electrolyte needed to produce the continuous supply of electrolyte contacting the substrate during electrodeposition. 
     
     
         17 . The method of  claim 16 , wherein the one or more seals are configured to form a chamber between the substrate and the flow manifold when the flow manifold and the substrate are engaged with said one or more seals; said flow manifold further comprising an electrolyte inlet configured to supply electrolyte to the chamber and an electrolyte outlet configured to drain used electrolyte from the chamber during electrodeposition. 
     
     
         18 . The method of  claim 17 , wherein the one or more seals comprise a perimeter-type seal. 
     
     
         19 . A flow manifold for delivering an electroplating solution to the surface of a substrate, said flow manifold comprising:
 (i) an electrolyte inlet, the electrolyte inlet upstream of;   (ii) a counter electrode, the counter electrode disposed on a surface of the flow manifold; and   (iii) an electrolyte outlet, the electrolyte outlet downstream of the counter electrode;   
       wherein the flow manifold is configured to supply a continuous flow of the electroplating solution from the electrolyte inlet, between the counter electrode a surface of the substrate so that electroplating can occur on the surface of the substrate, and then drain via the electrolyte outlet. 
     
     
         20 . The flow manifold of  claim 19 , configured to produce a substantially laminar flow or a turbulent flow of the electroplating solution between the surface of the substrate and the counter electrode. 
     
     
         21 . The flow manifold of  claim 20 , further comprising one or more seals, said seals configured to channel the flow of electroplating solution in order to maximize contact with the surface of the substrate and minimize the amount of plating solution needed to produce the continuous flow of the electroplating solution contacting the substrate during electrodeposition. 
     
     
         22 . The flow manifold of  claim 21 , further comprising one or more overflow channels for collecting used electrolyte. 
     
     
         23 . The flow manifold of  claim 21 , wherein the one or more seals are configured to form a chamber between the surface of the substrate and the flow manifold when the flow manifold and the substrate are engaged with said one or more seals. 
     
     
         24 . The flow manifold of  claim 23 , wherein the one or more seals comprise a perimeter-type seal.