Multi-step electrochemical copper deposition process with improved

Abstract

A multi-step electrochemical method for forming a copper metallurgy on an integrated circuit which has high aspect ratio contact/via openings is described. The method is designed to give good coverage and gap filling capability as well as high production throughput by performing the electrochemical deposition of copper in two deposition stages with an dwell period between the stages. The process utilizes a copper plating electrolyte which contains an added brightener and leveler. The first deposition is done at a low current density which provides good coverage resulting from a high throwing power. The high aspect ratio contact/via openings are covered with a substantial thickness of a uniform, high quality copper coating. During the deposition, the concentration of brightener becomes depleted in the base region of high aspect ratio contacts or vias. The concentration of brighteners, is replenished in these regions by diffusion during a brief dwell period wherein the plating current is stopped. Next, a high current density is applied whereby the contact/vias are filled and additional copper is deposited over them at a high deposition rate. The greatest throughput benefits are realized, by way of the high current density step, when the process is applied to the formation of a dual damascene metallurgy.