Spontaneous metal deposition from organic solutions for electronic materials applications

Electrochemical deposition (ECD) has been used widely in the electronics industry. A novel "galvanic deposition" process was used for spontaneous and selective ECD of metal from organic solutions in contrast to the more conventional aqueous media. The more noble metal ions loaded in the organic solution are reduced and deposited onto the less noble metal substrate, which is simultaneously dissolved into the organic.;Cu and Pd seed layers have been successfully deposited from organic solutions onto patterned and unpatterned pure aluminum and Al(0.5wt%Cu) thin films using this immersion displacement process. The Cu and Pd deposits were effectively used as catalytic sites for subsequent conventional electroless or electrolytic copper deposition.;Further studies were performed to modify and optimize the organic deposition solution composition. These modified organic solutions could be used to deposit nearly continuous copper films on both unpatterned and patterned aluminum substrates. A patent disclosure on the modified organic deposition process was made to the University of Missouri and will be officially filed with the U.S. Patent Office.;The EIS technique was one method used to characterize these high resistivity organic media. The organic solution resistivities were determined to be in the range of ∼108 O-cm but decreased to ∼10 6 O-cm with the addition of some modifying additives.;Pd and Cu deposition have also been accomplished on various blanket and patterned Ti, TiN, Ta, and TaN barrier films. Some pre-treatment or in-situ etching in combination with ultrasonic or intensive mechanical agitation was necessary to activate the surface and enhance the metal deposition reaction. After seeding, continuous copper films were built up using a conventional electroless or electroplating process.