Electric field initiated electroless metal deposition

Abstract

A technique for utilizing an electric field to initiate electroless deposition of a material to form layers and/or structures on a semiconductor wafer. The wafer is disposed between a positive electrode and a negative electrode and disposed so that its deposition surface faces the positive electrode. A conductive surface on the wafer is then subjected to an electroless copper deposition solution. When copper is the conductive material being deposited, positive copper ions in the solution are repelled by the positive electrode and attracted by the negatively charged wafer surface. Once physical contact is made, the copper ions dissipate their charges by accepting electrons from the conductive surface, thereby forming copper atoms on the surface. The deposited copper have the catalytic properties so that when a reductant in the solution is absorbed at the copper sites and then oxidized, additional electrons are released into the conductive surface. The formation of the initial layer of copper functions as a seed layer for further electroless growth of copper. The same electroless deposition solution can be used for both the initial activation layer and the additional autocatalytic growth on to the seed layer.