IN-SITU QUADRUPOLE MASS-SPECTROSCOPY STUDIES OF WATER AND SOLVENT COORDINATION TO COPPER(II) BETA-DIKETONATE PRECURSORS - IMPLICATIONS FOR THE CHEMICAL-VAPOR-DEPOSITION OF COPPER

The incorporation of Cu(II) beta-diketonates in technologically useful chemical vapor deposition (CVD) processes requires identifying the na ture of the coordinated complexes that result from variations in the m ethods used for precursor preparation, and exploring their effects on its stability and performance. Accordingly, in situ quadrupole mass sp ectrometry (QMS) was employed to investigate the gas-phase evolution o f various coordinated forms of Cu-II(hfac)(2) and Cu-II(tdf)(2), where tdf= ,3,3,7,7,8,8,9,9,9-tetradecafluorononane-4,6-dione and hfac = he xafluoroacetylacetonate, to determine the nature of these coordinated complexes and elucidate the desorption energetics of associated additi ves. Careful analyses of complex fragmentation patterns during its sub limation and transport to the CVD reactor were performed under a varie ty of electron energies to develop an understanding of the effects of synthetic variations on precursor coordination, determine the fragment ation modes of the parent molecular ions and associated ionic fragment s, and identify the mechanisms of precursor-additive interactions. In particular, it was found that Cu(hfac)(2) coordinates with water, meth anol, or ethanol, but not with 2-propanol. Additionally, QMS studies o f Cu(hfac)(2) seem to indicate that the use of methanol in the final r ecrystallization step involved in its synthesis yields a mixture of th e coordinated complexes Cu-II(hfac)(2) . H2O . CH3OH, Cu-II(hfac)(2) . 2H(2)O, and Cu-II(hfac)(2) . 2CH(3)OH. Similarly, in the case of Cu-I I(tdf)(2), the use of ethanol and trichloromethane appears to produce a mixture of the coordinated complexes Cu-II(tdf)(2) . C2H5OH . H2O, C u-II(tdf)(2) . C2H5OH, and Cu-II(tdf)(2) . 2H(2)O. By determining the temperature above which solvent molecules decoordinate from the copper precursor, reliable and reproducible processing windows were identifi ed for the delivery of the pure precursors to the reaction zone, regar dless of the synthetic technique used. It is thus shown that, by elimi nating the effects of synthesis-induced variations in source coordinat ion, copper beta-diketonates can be successfully and reliably incorpor ated in industrially compatible CVD processes for ULSI applications wi thout the need for costly precursor purification procedures.