Via anchor profile control

Abstract

Improved control of via anchor profiles in metals at a contact layer can be achieved by slowing down an anchor etching process and by introducing a passivation operation. By first passivating a metallic surface, etchants can be prevented from dispersing along grain boundaries, thereby distorting the shape of the via anchor. An iterative scheme that involves multiple cycles of alternating passivation and etching operations can control the formation of optimal via anchor profiles. When a desirable anchor shape is achieved, the anchor maintains structural integrity of the vias, thereby improving reliability of the interconnect structure.

Dependencies are inferred from the claim text.