Direct Plating of Low Resistivity Bright Cu Films onto TiN Barrier Layer via Pd Activation

Abstract

For seedless electroplating of low resistivity Cu film applicable to deep submicrometer damascene feature, Pd activation was introduced to direct Cu electroplating onto a high resistivity TiN barrier to get a high quality Cu film. Displacement-deposited Pd particles on the TiN substrate acted as nucleation sites for Cu plating. This high-density instantaneous nucleation made it possible to deposit a continuous, bright Cu film with low resistivity of 3.1 mV cm ~after annealing!. Aided by small amounts of benzotriazole, Pd activation also gave way to the application of seedless plating to superfilling of a deep submicrometer damascene structure, where the formation of the seed layer had been a critical issue. Poor adhesion between plated Cu and Pd activated TiN substrate was greatly improved by the addition of poly~ethylene glycol!. The change in film characteristics was found to be negligible.