Electrochemical methods for polishing copper films on semiconductor substrates

Abstract

Methods for electrochemically polishing copper films on semiconductor substrates use an alkaline solution with a pH in the range of about 8.0 to 10.5. A constant current density of from 5 to 100 amperes per square foot is applied to an electrochemical cell formed by an electrode, the alkaline solution and the copper film. Copper is removed at a rate of from 500 to 10,000 angstroms per minute. The end point for the electro-polishing is detected by a sudden change in applied voltage. The alkaline polishing solution may also contain copper ions so that when the current direction is reversed, copper is deposited onto the copper film. Furthermore, this copper deposition will occur selectively on the exposed copper surface but not on the exposed barrier layer surface. Hence, the method can compensate for dishing and erosion by re-depositing copper in regions after too much copper was removed from those regions.

Dependencies are inferred from the claim text.