IN-SITU MASS-SPECTRAL AND INFRARED STUDIES OF THE GAS-PHASE EVOLUTIONAND DECOMPOSITION PATHWAYS OF CU-II(HFAC)(2) - APPLICATION IN THE DEVELOPMENT OF PLASMA-ASSISTED CHEMICAL-VAPOR-DEPOSITION OF COPPER

Results are presented from in situ, real-time, mass spectral, and infr ared studies of the gas-phase evolution and decomposition pathways of the copper(II) beta-diketonate precursor s(1,1,1,5,5,5-hexafluoroacety lacetonato)copper(II) Cu-II(hfac)(2), during plasma-assisted CVD (PACV D) of copper. Quadrupole mass spectrometry (QMS) investigations focuse d on determining the ionization efficiency curves and appearance poten tials of Cu-II(hfac)(2) under real CVD processing conditions. The resu lting curves and associated potentials were then employed to identify the most likely precursor decomposition pathways and examine relevant implications for thermal and plasma-assisted CVD of copper from Cu-II( hfac)(2). The QMS studies were complemented with real-time Fourier-tra nsform infrared (FTIR) spectroscopy of the CVD processing environment to establish a basic understanding of plasma effects on copper precurs or evolution and decomposition, and to determine optimum plasma CVD pr ocessing windows. Real-time FTIR absorption spectra of the gas-phase s pecies in the CVD reactor were collected and analyzed for various plas ma power densities. Key changes in precursor stretching and bending in frared (IR) bands were subsequently identified through a systematic co mparison of the spectra of hydrogen plasma-exposed Cu-II(hfac)(2), col lected as a function of varying plasma power density, and the fingerpr int spectra of nonplasma-exposed H(hfac) and Cu-II(hfac)(2). The resul ting FTIR findings were used to develop optimum plasma processing cond itions for providing the high concentration of reactive hydrogen speci es needed for the clean and efficient reduction of the precursor, with out inducing undesirable gas-phase reactions. The results demonstrated that FTIR does provide a reliable in situ, accurate, and nonintrusive technique for monitoring the gas-phase evolution of metallorganics an d associated reactants in the CVD reactor and allowing critical adjust ments for optimal copper film quality.