No abstract

Results are presented from in situ, real-time, mass spectral, and infrared studies of the gas-phase evolution and decomposition pathways of the copper(II) ~-diketonate precursor bis (l,l,l,5,5,5-hexafluoroacetylaeetonato) copper(II),Cun(hfac)2, during plasma-assisted CVD (PACVD) of copper. Quadrupole mass spectrometry (QMS) investigations focused on determining the ionization efficiency curves and appearance potentials of Cu~(hfac)~ under real CVD processing conditions. The resulting 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~(hfae)2. The QMS studies were complemented with real-time Fourier-transform infrared (FTIR) spectroscopy of the CVD processing environment to establish a basic understanding of plasma effects on copper precursor evolution and decomposition, and to determine optimum plasma CVD processing windows. Real-time FTIR absorption spectra of the gas-phase species in the CVD reactor were collected and analyzed for various plasma power densities. Key changes in precursor stretching and bending infrared (IR) bands were subsequently identified through a systematic comparison of the spectra of hydrogen plasma-exposed Cu~(hfac)2, collected as a function of varying plasma power density, and the fingerprint spectra of nonplasma-exposed H(hfac) and Cun(hfac)~. The resulting FTIR findings were used to develop optimum plasma processing conditions for providing the high concentration of reactive hydrogen species needed for the clean and efficient reduction of the precursor, without 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 and associated reactants in the CVD reactor and allowing critical adjustments for optimal copper film quality.