Use of a capping layer to reduce particle evolution during sputter pre-clean procedures

Abstract

A process for preparing a surface of a lower level metal structure, exposed at the bottom of a sub-micron diameter opening, to allow a low resistance interface to be obtained when overlaid with an upper level metal structure, has been developed. A disposable, capping insulator layer is first deposited on the composite insulator layer in which the sub-micron diameter opening will be defined in, to protect underlying components of the composite insulator from a subsequent metal pre-metal procedure. After anisotropically defining the sub-micron diameter opening in the capping insulator, and composite insulator layers, and after removal of the defining photoresist shape, an argon sputtering procedure is used to remove native oxide from the surface of the lower level metal structure. In addition to native oxide removal the argon sputtering procedure, featuring a negative DC bias applied to the substrate, also removes the capping insulator layer from the top surface of the composite insulator layer. An in situ metal deposition then allows a clean interface to result between the overlying metal layer, and the underlying plasma treated, metal surface.