The present technique is directed toward the fabrication of integrated
circuits and provides for the production of a hardened metal layer on the
surface of a semiconductor wafer to reduce the amount of material removed
during chemical mechanical planarization (CMP) of the metal layer. This
hardened layer may be produced, for example, by oxidizing the metal
surface and/or coating the metal surface with a polymer. In one
implementation, a relatively thick and dense oxide layer is formed on the
wafer metal surface prior to CMP, by injecting, for example, an oxidant,
such as oxygen or ozone, near the end of an annealing cycle. The hardened
metal beneficially protects recessed regions from CMP chemical attack and
CMP pad deformation, and thus reduces the thickness-to-planarity,
dishing, and waste generation realized during CMP.