Abstract
Electroless plating is used commercially for the simple and low cost deposition of metal coatings on relatively large area substrates. For plating of very fine metal patterns such as (submicron) contact holes in integrated circuit technology, anomalous behavior has been found with respect to the initiation and film growth. First, the areas to be metallized are so small that mass transport by nonlinear diffusion, which is considerably enhanced compared to linear diffusion to large area substrates, must be considered. A second effect that must be considered is electrical connections within the substrate. An ohmic connection of a small hole to a large substrate leads to plating potential pinning of this hole, i.e., the local potential at the contact hole during plating is determined by the steady‐state value that is established at the large area substrate. Dependent on the exact conditions, these two geometrical effects can lead to both an enhanced growth rate of the metal compared to bulk substrates, or to no metal deposition at all. The experimental observations can be explained by the mixed potential theory. This insight in turn indicates how uniform deposition rates in contact holes still can be achieved, regardless of their exact geometry.