In Situ Mass Spectral and Infrared Studies of the Gas‐Phase Evolution and Decomposition Pathways of Cu II  ( hfac ) 2 : Application in the Development of Plasma‐Assisted Chemical Vapor Deposition of Copper

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.

Thermal Decomposition Mechanism of Ti ( O ‐ iPr ) 2 ( DPM ) 2

“…The complicated peaks between 1400 and 1600 cm Ϫ1 are from the vibration of the C-O and the C-C bonds in the ring structure of the metal complex. We have assigned the peaks at 1599 cm Ϫ1 (also 1582 cm Ϫ1 ) and 1567 cm Ϫ1 to the C-O and the C-C bonds, respectively, following the assignment by Pinchas et al, 16 Richardson et al, 17 and recently by Zheng et al, 18 which is opposite to the conclusion by Nakamoto and Martell 19 and Mikami et al 20 The assignment agrees with our observation of the peak-intensity change at elevated temperatures as dis-cussed later. Another group of peaks between 900 and 1300 cm Ϫ1 is due to the C-C(CH 3 ) 3 group in the ligand.…”

Atomic Layer Deposition of High-Purity Palladium Films from Pd(hfac)2 and H2 and O2 Plasmas

“…The precursor-only spectrum in Figure a shows several absorption peaks in the region 1100–1350 cm –1 , which can be attributed to CF 3 symmetric and asymmetric stretching vibrations. , The peak present at 1108 cm –1 can be assigned to the bending vibration of C–H. , The other peaks visible in the region between 1450 and 1700 cm –1 are due to the stretching vibrations of CC ,− and CO. , All of these absorption peaks result from the Pd(hfac) 2 precursor.…”

Thermal Decomposition Mechanism of Sr(DPM)[sub 2]

“…The vibrational modes of the C-O and the C-C bonds in the ligand ring structure appear between 1400 and 1600 cm Ϫ1 . We have assigned the 1595 cm Ϫ1 (also 1579 cm Ϫ1 ) peak to the stretching mode of the C-O bond and the 1562 cm Ϫ1 peak to [(C-C) ϩ (C-O)] following the works by Pinchas et al, 16 Richardson et al, 17 and Zheng et al, 18 which is opposite to the assignment by Nakamoto and Martell 19 and Mikami et al 20 Peaks at 740, 758, and 869 cm Ϫ1 and those between 1130 and 1276 cm Ϫ1 represent various vibrational modes of the C-C(CH 3 ) 3 bond in the ring structure. Finally, the peak at 476 cm Ϫ1 is due to the stretching mode of the Sr-O bond.…”