ATMOSPHERIC-PRESSURE CHEMICAL VAPOR-DEPOSITION OF COPPER THIN-FILMS .1. HORIZONTAL HOT WALL REACTOR

We have studied the reaction kinetics of Cu chemical vapor deposition (CVD) by H-2 reduction of Cu(hfa)2 in a horizontal flow, atmospheric pressure, hot-wall CVD reactor. Using glass substrates, we can routinely deposit films at temperatures as low as 523 K and growth rates of 200 angstrom/min, with resistivities between 2-3-mu-OMEGA-cm. The reactor is operated at integral conversions of Cu(hfa)2, and the reaction kinetics are determined by analyzing the axial thickness profiles of the deposited films obtained under a series of different operating conditions (e.g. reactant composition, substrate temperature, and carrier gas flow rate). The steady-state growth rate exhibits saturation kinetics with respect to Cu(hfa)2 concentration, positive reaction order with respect to H-2, and negative reaction order with respect to H(hfa). We propose a mechanism based on dissociative adsorption of Cu(hfa)2 at vacant surface sites, followed by H-atom assisted desorption of H(hfa) ligands as the rate limiting step in the overall reaction. The resulting rate expression is combined with a reactor model based on a one-dimensional Cu(hfa)2 species conservation equation, and the calculated thickness profiles are compared with observed results to obtain estimates of the kinetic parameters.