Copper profile evolution in ultralarge scale integration via and trench structures was investigated for thermal low pressure, low temperature, chemical vapor deposition (LPCVD) from CuI(tmvs)(hfac). The investigation examined copper profiles in specialized cantilever structures as a function of systematic changes in key processing conditions, namely, substrate temperature, precursor flux, and hydrogen reactant flow. Resulting experimental observations from cross section scanning electron microscopy were incorporated in a fast analytical simulator, using a two-dimensional adsorption/re-emission model, to simulate copper profile evolution. The deposition profiles were simulated using a single rate limiting precursor model. A comparison of simulation results and actual experimental profiles for thermal LPCVD copper showed that species re-emission within the via and trench structures play a critical role in achieving conformal step coverage and complete filling. In additional, precursor flux and substrate temperature were identified as the dominant parameters in the species re-emission process, with the probability for re-emission being inversely proportional to substrate temperature and directly proportional to precursor flux. The results of this study were employed in the development of an optimum LPCVD process window for complete copper filling of aggressive via and trench structures at growth rates above 2000 Å/min and as-deposited resistivity below 2.0 μΩ cm.

Articles you may be interested inMorphology and growth mode of Al films deposited by chemical vapor deposition from dimethylethylamine alane on GaAs(001)2×4 surfaces J.Enhancement of titanium nitride barrier metal properties by nitrogen radical assisted metalorganic chemical vapor deposition Aluminum chemical vapor deposition with new gas phase pretreatment using tetrakisdimethylamino-titanium for ultralarge-scale integrated-circuit metallization In this article, the authors report the results of a study aimed at optimizing a manufacturable thermal copper-chemical vapor deposition process, using ͑tmvs͒ Cu I ͑hfac͒ as the source, where tmvsϭtrimethylvinylsilane and hfacϭhexafluoroacetylacetonate, and establishing associated material and process characteristics and performance. This study employed a two-stage design of experiments approach in conjunction with actual deposition runs on unpatterned silicon ͑Si͒ and titanium nitride ͑TiN͒ surfaces, as well as SEMATECH patterned TiN structures with feature sizes as small as 0.30 m with aspect ratio 6:1. All samples were analyzed by Auger electron spectroscopy, Rutherford backscattering, four-point resistivity probe, and cross-section scanning electron microscopy. The results of these analyses showed that precursor concentration, substrate temperature, and in situ predeposition substrate surface plasma treatment play a key role in achieving good conformality and complete filling at high growth rates in aggressive via and trench structures. Based on these findings, an optimum process window was identified and employed to demonstrate complete high growth rate ͑ϳ2000 Å/min͒ filling of 0.3 m, 6:1 aspect ratio, devices structures with pure copper at as-deposited resistivities of 1.8 ⍀ cm.

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.

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