Method of depositing films on aluminum alloys and films made by the method

Abstract

Method for depositing a metallic material on an aluminum alloy surface for galvanic displacement type deposition, electrodeposition or electroless deposition of a metallic film on the surface wherein the alloy surface is oxidized (e.g. anodized) to form aluminum oxide and the oxidized surface is etched to leave a partial thickness of a barier aluminum oxide on the alloy surface. The partial thickness of the barrier oxide is controlled by etching to form a porous, metallic particulate film for a thin barrier oxide, or a continuous metallic film for thicker barrier oxide. The metallic film then is electrodeposited or electroless deposited on the barrier film.

1 . Method of depositing a metallic material on a substrate, comprising the steps of providing a substrate comprising an alloy of aluminum and an alloying element, oxidizing a surface of the substrate to form aluminum oxide thereon, etching the oxidized surface to leave a partial thickness of a barrier aluminum oxide of said aluminum oxide on the surface, and depositing by galvanic displacement type deposition, electroless deposition or electrodeposition discrete metallic nanoparticles on the barrier oxide having a particle density of about 10 4  to about 10 12  particle/cm 2 .  
   
   
       2 . The method of  claim 1  wherein said etching is conducted to leave a barrier oxide portion having a partial thickness to increase nucleation of the discrete nanoparticles thereon.  
   
   
       3 . The method of  claim 1  wherein the substrate comprises a film or layer of the alloy.  
   
   
       4 . The method of  claim 1  wherein the alloying element includes one or more of Au, Cu, Cr, Mn, Mo, Ni, Si, Ta, Ti, or Zn.  
   
   
       5 . The method of  claim 1  wherein the surface is oxidized by anodizing, polishing, alkaline etching, acid pickling, electropolishing, or heating in an oxygen bearing atmosphere.  
   
   
       6 . The method of  claim 1  wherein the surface is acid etched by contact with a mixture of phosphoric acid and an inhibitor for aluminum dissolution.  
   
   
       7 . The method of  claim 6  wherein the inhibitor comprises chromic acid.  
   
   
       8 . The method of  claim 1  wherein the metallic material comprises one of Au, Ag, Pd, Cu, Ni, Pb, Cr, Fe, W, Mo, or Co.  
   
   
       9 . The method of  claim 1  wherein the substrate is disposed on a silicon wafer.  
   
   
       10 . A substrate comprising an alloy of aluminum and an alloying element, said substrate having a barrier oxide on a substrate surface and a porous, three dimensional structure of electrically interconnected, metallic nanoparticles deposited by electroless deposition or electrodeposition on the barrier oxide.  
   
   
       11 . The substrate of  claim 10  wherein the structure includes randomly packed, generally spherical metallic nanoparticles having a distribution of particle sizes.  
   
   
       12 . The substrate of  claim 10  wherein the nanoparticles have a particle diameter in the range of about 20 nm to about 1000 nm.  
   
   
       13 . The substrate of  claim 10  wherein the nanoparticles have an interparticle spacing sufficient to provide electrolyte access among the nanoparticles, providing a high surface area material.  
   
   
       14 . The substrate of  claim 10  wherein the structure has a ratio between electrolyte accessible area and geometric surface area of about 100 and above.  
   
   
       15 . Electrode comprising a substrate comprising an alloy of aluminum and an alloying element, said substrate having a barrier oxide on a substrate surface and a porous, electrolyte accessible, three dimensional structure of electrically interconnected, generally spherical, randomly packed metallic nanoparticles deposited by galvanic displacement type deposition, electroless deposition or electrodeposition on the barrier aluminum oxide.  
   
   
       16 . The electrode of  claim 15  wherein the nanoparticles have a particle diameter in the range of about 20 nm to about 1000 nm.  
   
   
       17 . The electrode of  claim 15  wherein the structure has a ratio between electrolyte accessible area and geometric surface area of about 100 and above.  
   
   
       18 . The electrode of  claim 15  wherein the barrier oxide film has been chemically etched.  
   
   
       19 . The electrode of  claim 15  wherein the substrate is disposed on a silicon wafer.  
   
   
       20 . Capacitor having an electrode in accordance with  claim 15 .  
   
   
       21 . Method of depositing a metallic material on a substrate, comprising the steps of providing a substrate comprising an alloy of aluminum and an alloying element, oxidizing a surface of the substrate to form aluminum oxide thereon, etching the oxidized surface to leave a partial thickness of a barrier aluminum oxide of said aluminum oxide on the surface, and depositing by galvanic displacement type deposition, electroless deposition or electrodeposition a continuous metallic film on the barrier oxide.  
   
   
       22 . The method of  claim 21  wherein said etching is conducted to leave a barrier oxide portion having a partial thickness to deposit a continuous metallic film.  
   
   
       23 . The method of  claim 21  wherein the substrate comprises a film or layer of the alloy.  
   
   
       24 . The method of  claim 21  wherein the alloying element includes one or more of Au, Cu, Cr, Mn, Mo, Ni, Si, Ta, Ti, or Zn.  
   
   
       25 . The method of  claim 21  wherein the surface is oxidized by anodizing, polishing, alkaline etching, acid pickling, electropolishing, or heating in an oxygen bearing atmosphere.  
   
   
       26 . The method of  claim 21  wherein the surface is acid etched by contact with a mixture of phosphoric acid and an inhibitor for aluminum dissolution.  
   
   
       27 . The method of  claim 26  wherein the inhibitor comprises chromic acid.  
   
   
       28 . The method of  claim 21  wherein the metallic material comprises one of Au, Ag, Pd, Cu, Ni, Pb, Cr, Fe, W, Mo, or Co.  
   
   
       29 . The method of  claim 21  wherein the substrate is disposed on a silicon wafer.