A novel model of hydrogen plasma assisted chemical vapor deposition of copper

tl new distsibuted parameter model of a capacitively coupled rf hydrogen di scharge including a copper precursor has been developed, from the first thr ee moments of the Boltzmann equation. The model predicts the concentrations and fluxes of(1) the positive ions H+, H-2(+) and H-3(+) (2) the electrons and (3) atomic hydrogen, under the conditions that produce low resistivity copper films with the precursor Cu(II) hexa-fluoroacetylacetonate (Cu(HFA) (2)). Since Cu(HFA)(2) is consumed predominantly at the wafer, an analytica l model also has been derived to estimate the concentration distribution of Cu(HFA)(2) in the reactor, as a function of the operating conditions. Copp er is formed on the wafer via a surface reaction between the adsorbed precu rsor and atomic hydrogen, that is produced in the plasma by the dissociatio n of molecular hydrogen. Tbt:hydrogen plasma model has been coupled with th e precursor transport model using a rate expression that reflects the PACVD surface reaction mechanism, to explain the experimental observations and s uggest process windows for high copper deposition rates and film purity. Ne w data were taken and are reported here to test the model definitively. (C) 1999 Elsevier Science S.A. All rights reserved.