CVD COPPER DEPOSITION FROM CU-I(HFAC)TMVS STUDIED THROUGH A MODELING EXPERIMENTAL-DESIGN

Thin copper films were grown using hexafluoroacetylacetonato-copper(I) trimethylvinylsilane [Cu(hfac)tmvs]. This precursor was delivered thr ough a bubbler using hydrogen as carrier gas. Water vapour was used as reactant. The films were deposited on sputtered titanium nitride subs trate, at wafer temperatures between 100 degrees C and 210 degrees C. An excess of water leads to the formation of copper oxide and films wi th a high resistivity. But no water leads to a poor nucleation and ver y low deposition rate. The way of injecting water plays an important r ole in the process : water at the beginning of the deposition time hel ps the nucleation and has to be stopped after a few minutes to avoid t he oxidation of the film. An optimization of the operating conditions was carried out through the use of screening and modeling experimental designs. The influence of substrate temperature, carrier gas Row, wat er flow, water injection time and bubbler pressure was studied and lea ds to experimental laws, which are showing the dependence of the resis tivity and the deposition rate with any of these parameters. An optimu m working point was found, in term of resistivity. In that case, X-Ray Photoelectron Spectroscopy (XPS) indicate a pure copper phase. The re sistivity was 1.9 mu Omega.cm after annealling. The adhesion on TiN su bstrate is excellent according to the ''scotch tape'' test. Very high conformal deposition is obtained on 0,4 mu m width, 1 mu m deep.