Method of cleansing vias in semiconductor wafer having metal conductive layer

Abstract

Non-volatile and oxide residues that form during semiconductor processing are removed from the semiconductor structure in a two-stage process. An inert gas and a reducing gas are introduced to the reactor. In the first stage, the non-volatile contaminants are sputtered from the semiconductor structure by creating a plasma to ionize the inert gas. The power applied to the plasma is preferably high enough to give the ions of the inert gas a high degree of directionality as they approach the structure. The first stage is continued until the non-volatile contaminants have been sufficiently removed from the structure. In the second stage, the power is reduced and the reducing gas (e.g., hydrogen) reacts with the oxides (e.g., copper oxide) to form elemental metal and water vapor. During the second stage there is no appreciable sputtering, and therefore the damage to the structure is limited as compared with processes that use sputtering and reduction simultaneously.

Dependencies are inferred from the claim text.