Electroplating apparatus

Abstract

Embodiments of the invention contemplate the formation of a low cost solar cell using a novel high speed electroplating method and apparatus to form a metal contact structure having selectively formed metal lines using an electrochemical plating process. The apparatus and methods described herein remove the need to perform one or more high temperature screen printing processes to form conductive features on the surface of a solar cell substrate. The resistance of interconnects formed in a solar cell device greatly affects the efficiency of the solar cell. It is thus desirable to form a solar cell device that has a low resistance connection that is reliable and cost effective. Therefore, one or more embodiments of the invention described herein are adapted to form a low cost and reliable interconnecting layer using an electrochemical plating process containing a common metal, such as copper.

1 . An apparatus for forming a metal layer on a substrate, comprising:
 a masking plate having a body, a first surface and a second surface, the masking plate having a plurality of apertures that extend through the body between the first surface and the second surface;   an electrical contact formed on the first surface of the masking plate and in communication with a power supply;   a thrust plate that is adapted to urge a metallized surface of a substrate against the electrical contact and the first surface of the masking plate; and   an electrode that is in electrical communication with the power supply, the power supply configured to electrically bias the electrode relative to the electrical contact.   
     
     
         2 . The apparatus of  claim 1 , wherein the masking plate is formed from a material selected from the group consisting of glass, plastic and ceramic. 
     
     
         3 . The apparatus of  claim 2 , wherein the electrical contact is formed from a material selected from the group consisting of platinum, gold, nickel, graphite and copper. 
     
     
         4 . The apparatus of  claim 1 , wherein the electrode has a spiral shape. 
     
     
         5 . The apparatus of  claim 3 , further comprising a diffuser plate that is positioned between the electrode and the metallized surface, wherein the diffuser plate is adapted to rotate relative to the metallized surface of the substrate. 
     
     
         6 . The apparatus of  claim 3 , further comprising a diffuser plate that is positioned between the electrode and the metallized surface, wherein the diffuser plate is adapted to move linearly or vibrate relative to the metallized surface of the substrate. 
     
     
         7 . An apparatus for forming a metal layer on a solar cell substrate, comprising:
 a masking plate comprising a body formed of dielectric material, a first surface and a second surface, the masking plate having a plurality of apertures that extend through the body between the first surface and the second surface;   a plurality of electrical contacts formed on the first surface of the masking plate;   a thrust plate adapted to urge a surface of a substrate against the plurality of electrical contacts and the first surface of the masking plate;   an actuator coupled to the thrust plate; and   an electrode that is in electrical communication with a power supply, wherein the power supply is configured to electrically bias the electrode relative to the plurality of electrical contacts.   
     
     
         8 . The apparatus of  claim 7 , wherein the electrode is non-consumable. 
     
     
         9 . The apparatus of  claim 7 , wherein the electrode is consumable. 
     
     
         10 . The apparatus of  claim 7 , wherein the electrode is formed from a material selected from the group consisting of titanium, platinum, copper and phosphorus. 
     
     
         11 . The apparatus of  claim 8 , further comprising a polymeric material disposed at least partially on the first surface of the masking plate. 
     
     
         12 . The apparatus of  claim 11 , wherein the plurality of electrical contacts are formed from a material selected from the group consisting of platinum, gold, nickel, graphite and copper. 
     
     
         13 . An apparatus for forming a metal layer on a solar cell substrate, comprising:
 a masking plate comprising a body, a first surface and a second surface, the masking plate having a plurality of apertures that extend through the body between the first surface and the second surface;   a plurality of electrical contacts at least partially recessed within the first surface of the masking plate;   a thrust plate adapted to urge a surface of a substrate against the plurality of electrical contacts and the first surface of the masking plate; and   a non-consumable electrode electrically coupled to a power supply, wherein the power supply is configured to electrically bias the non-consumable electrode relative to the plurality of electrical contacts.   
     
     
         14 . The apparatus of  claim 13 , wherein the masking plate is formed from a material selected from the group consisting of glass, plastic and ceramic. 
     
     
         15 . The apparatus of  claim 14 , further comprising a polymeric material disposed at least partially on the first surface of the masking plate. 
     
     
         16 . The apparatus of  claim 15 , wherein the plurality of electrical contacts are formed from a material selected from the group consisting of platinum, gold, nickel, graphite or copper. 
     
     
         17 . The apparatus of  claim 16 , wherein the electrode is formed from a material selected from a group consisting of titanium, platinum, copper and phosphorus. 
     
     
         18 . The apparatus of  claim 17 , wherein the plurality of apertures extending through the body form a pattern of interdigitated grid lines. 
     
     
         19 . The apparatus of  claim 18 , wherein the surface area of the electrode is about 2 to about 10 times greater than the cross sectional area of the plurality of apertures. 
     
     
         20 . The apparatus of  claim 19 , wherein the electrode has a spiral shape.