Infrared Spectroscopy of Trimethylaluminum and Dimethylaluminum chloride adsorbed on Alumina

Soto, C.; Wu, Ruowen; Bennett, Dennis W.

doi:10.1021/cm00046a024

Cited by 31 publications

(39 citation statements)

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“…The red shift is confirmed not to be an artifact of the BML-RAIRS method; a separate experiment using attenuated total reflection measures a shift of a similar magnitude (Figure S1). In this work, we find no clear evidence for a feature near 1250 cm –1 , which would be indicative of a bridging configuration, μ 2 -CH 3 * . ,, This differs from some previous work that found evidence for this moiety on surfaces exposed to TMA. ,,, …”

Section: Resultscontrasting

confidence: 99%

“…In this work, we find no clear evidence for a feature near 1250 cm −1 , which would be indicative of a bridging configuration, μ 2 -CH 3 *. 49,59,60 This differs from some previous work that found evidence for this moiety on surfaces exposed to TMA. 34,49,57,60 After 29 cycles ending with TMA, the spectrum in Figure 1c is obtained.…”

Section: ■ Resultscontrasting

confidence: 97%

“…49,59,60 This differs from some previous work that found evidence for this moiety on surfaces exposed to TMA. 34,49,57,60 After 29 cycles ending with TMA, the spectrum in Figure 1c is obtained. Absorption near the LO phonon mode position (940 cm −1 ) dominates the spectrum.…”

Section: ■ Resultscontrasting

confidence: 97%

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Atomic Layer Deposition of Al₂O₃Using Trimethylaluminum and H₂O: The Kinetics of the H₂O Half-Cycle

2020

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Atomic layer deposition (ALD) of Al 2 O 3 using trimethylaluminum and H 2 O is known to proceed through sequential surface reactions that leave the surface alternately terminated with AlCH 3 and OH groups. Using in situ reflection− absorption infrared spectroscopy in a flow reactor, we monitor the consumption of AlCH 3 groups by brief pulses of H 2 O at temperatures between 105 and 300 °C. At low temperatures, the surface reactions occur by what appears to be two stages that can be fit to a biexponential decay. Rate laws based on species of AlCH 3 groups that also predict a biexponential decay are found to depend on unrealistic activation energies for their constituent reactions when applied to the data. However, a model in which the effective activation energy changes linearly with AlCH 3 coverage does adequately fit the data. This model produces the apparent biexponential decay at low temperatures, and it confirms prior suggestions of a coverage dependence in the rate constant. The decrease in the effective activation energy with increasing coverage can be interpreted in terms of a cooperative effect between adjacent AlCH 3 groups. These findings may provide a framework for further studies, and both the kinetic model and parametric fits to the data may be useful in the construction of models of this important ALD process.

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Section: Resultscontrasting

confidence: 99%

Section: ■ Resultscontrasting

confidence: 97%

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Atomic Layer Deposition of Al₂O₃Using Trimethylaluminum and H₂O: The Kinetics of the H₂O Half-Cycle

2020

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“…Engelsberg and co-workers9,10 were the Ðrst to Ðnd that TMA reacts with the OH groups of alumina at room temperature. Since then, other investigations have been carried out both at room temperature1,2,4,6,11 and at higher temperatures.1,3,6,12 Soto et al 1,11 and Bertolet and Rogers4 suggested, on the basis of IR analysis of the CH bending band of the AlÈMe groups, that TMA reacts at room temperature with the OH groups of hydroxylated alumina to form dimethylaluminium (OAlMe 2 ) species, with the release of methane. Soto et al11 showed further that, when the surface is heated above 423 K, the species react with the neighbouring OH groups to OAlMe 2 form monomethylaluminium and more methane.…”

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confidence: 99%

Successive reactions of gaseous trimethylaluminium and ammonia on porous alumina

Puurunen¹,

Lindblad

Root

et al. 2001

Phys. Chem. Chem. Phys.

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Successive reactions of gaseous trimethylaluminium (TMA) and ammonia on porous alumina were studied with the goal of Ðnding suitable process conditions for preparing aluminium nitride (AlN) by atomic layer deposition (ALD), a technique based on separate saturating gasÈsolid reactions. The reaction of TMA was studied at 353È623 K on alumina dehydroxylated at 473È1073 K, and the following reaction of ammonia at 423È823 K. Reference samples were prepared by reacting ammonia at 623 and 823 K with alumina dehydroxylated at 833 K. The samples were characterised by elemental analysis of carbon and nitrogen and by IR and 1H NMR. TMA reacted with alumina in a saturating manner at 353È573 K. Reaction took place through ligand exchange with surface OH groups, with release of methane, and through dissociation of TMA on pairs of coordinatively unsaturated Al and O ions. Aluminium-bonded methyl groups remained on the surface. Decomposition of TMA occurred at 600 K and above. Ammonia had reacted with most of the methyl groups by 573 K, but 723 K was required to remove them all. Primary, secondary and tertiary amino groups were formed in the reaction, and ammonia molecules were adsorbed on the surface. The average H/N ratio in the amino groups decreased with increasing reaction temperature. Good temperatures for AlN deposition by ALD seem to be any temperature up to 573 K for the TMA reaction and 723 K or above for the ammonia reaction.

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“…Acknowledgements surface-area alumina [24]. Of particular note is the fact that the thin oxide layer allows the low-…”

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An infrared spectroscopic investigation of thin alumina films: measurement of acid sites and surface reactivity

Kaltchev

1999

Surface Science

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The surface chemical activity of an alumina films grown on Mo(100) by oxidation of aluminum evaporated onto the surface and oxidized using water is examined using Auger, X-ray photoelectron and reflection/absorption infrared spectroscopies. The formation of alumina is confirmed using Auger and X-ray photoelectron spectroscopy from the positions and intensities of the aluminum features and using reflection-absorption infrared spectroscopy from the longitudinal optical modes of the Al-O bonds measured at~935 cm−1. The presence of surface hydroxyls is monitored by forming films using D 2 O which are evidenced by a feature at~2700 cm−1. Ammonia adsorption on a dehydroxylated surface yields a single peak at 1260 cm−1 due to ammonia adsorbed at a surface Lewis site where the principle symmetry axis of ammonia is oriented perpendicularly to the surface plane. Ammonia also appears to adsorb at Lewis sites on a hydroxylated surface with a slightly different adsorption geometry from that on a dehydroxylated surface. Finally, the chemistry of trimethyl aluminum adsorbed on the planar hydroxylated alumina surface is compared with that found on high-surface-area c-alumina where the spectra and the chemistry found in both régimes is exactly identical except that the low-frequency methyl bending modes (at 769 and 718 cm−1) are not obscured on the thin film by the intense substrate whereas they are on the high-surface-area support.

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Infrared Spectroscopy of Trimethylaluminum and Dimethylaluminum chloride adsorbed on Alumina

Cited by 31 publications

References 0 publications

Atomic Layer Deposition of Al₂O₃Using Trimethylaluminum and H₂O: The Kinetics of the H₂O Half-Cycle

Atomic Layer Deposition of Al₂O₃Using Trimethylaluminum and H₂O: The Kinetics of the H₂O Half-Cycle

Successive reactions of gaseous trimethylaluminium and ammonia on porous alumina

An infrared spectroscopic investigation of thin alumina films: measurement of acid sites and surface reactivity

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Infrared Spectroscopy of Trimethylaluminum and Dimethylaluminum chloride adsorbed on Alumina

Cited by 31 publications

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Atomic Layer Deposition of Al2O3Using Trimethylaluminum and H2O: The Kinetics of the H2O Half-Cycle

Atomic Layer Deposition of Al2O3Using Trimethylaluminum and H2O: The Kinetics of the H2O Half-Cycle

Successive reactions of gaseous trimethylaluminium and ammonia on porous alumina

An infrared spectroscopic investigation of thin alumina films: measurement of acid sites and surface reactivity

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Product

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Atomic Layer Deposition of Al₂O₃Using Trimethylaluminum and H₂O: The Kinetics of the H₂O Half-Cycle

Atomic Layer Deposition of Al₂O₃Using Trimethylaluminum and H₂O: The Kinetics of the H₂O Half-Cycle