Alumina thin films prepared by direct liquid injection chemical vapor deposition of dimethylaluminum isopropoxide: a process‐structure investigation

Chemical Vapor Deposition

Charvillat

Esvan

et al. 2015

Self Cite

We present the direct liquid injection CVD of aluminum oxide and oxycarbide thin films using dimethylaluminum isopropoxide at high process temperature (500-700 8C) with the addition of O 2 gas, and at low temperature (150-300 8C) with the addition of H 2 O vapor. Very smooth films with typical roughness values lower than 2 nm are obtained. The thin films are composed of an amorphous material. The composition evolves as a function of temperature from that of a partial hydroxide to a stoichiometric oxide at low deposition temperature (150-300 8C), and from that of a stoichiometric oxide to a mixture of an oxide with an (oxy) carbide at higher temperature (500-700 8C).

Section: Introductionsupporting

confidence: 62%

A Process‐Structure Investigation of Aluminum Oxide and Oxycarbide Thin Films prepared by Direct Liquid Injection CVD of Dimethylaluminum Isopropoxide (DMAI)

Chemical Vapor Deposition

Charvillat

Esvan

et al. 2015

Self Cite

“…2d and SI Fig. S2c) [29]. After annealing in air, films of about 180 nm show a behavior similar to the ALD films with the partial oxidation of Ti at 500 8C (Fig.…”

Section: Materials Characterizationmentioning

confidence: 54%

“…S2b). Moreover, this difference in morphology is correlated to a significant difference in composition with the formation of a stoichiometric oxide using DLI DMAI at 500 8C [29], in contrast to the formation of partly hydroxylated aluminum oxide (O/Al ¼ 1.80) when using DLI ATI at 420 8C [30]. The crystal structure of the Ti films before and after deposition of alumina was monitored using XRD.…”

Section: Materials Characterizationmentioning

confidence: 99%

Amorphous alumina thin films deposited on titanium: Interfacial chemistry and thermal oxidation barrier properties

Physica Status Solidi (a)

Charvillat

Thébault

et al. 2015

Self Cite

bilayer stacks are used as model systems to investigate the role of atomic layer deposition (ALD) and chemical vapor deposition (CVD) to prepare 30-180 nm thick amorphous alumina films as protective barriers for the medium temperature oxidation (500-600 8C) of titanium, which is employed in aeronautic applications. X-ray diffraction (XRD), transmission electron microscopy (TEM) with selected area electron diffraction (SAED), and X-ray photoelectron spectroscopy (XPS) results show that the films produced from the direct liquid injection (DLI) CVD of aluminum tri-isopropoxide (ATI) are poor oxygen barriers. The films processed using the ALD of trimethylaluminum (TMA) show good barrier properties but an extensive intermixing with Ti which subsequently oxidizes. In contrast, the films prepared from dimethyl aluminum isopropoxide (DMAI) by CVD are excellent oxygen barriers and show little intermixing with Ti. Overall, these measurements correlate the effect of the alumina coating thickness, morphology, and stoichiometry resulting from the preparation method to the oxidation barrier properties, and show that compact and stoichiometric amorphous alumina films offer superior barrier properties.

“…14 Alternatively to evaporated ATI, another CVD process to synthesize amorphous alumina films was investigated by using the direct liquid injection (DLI) technology with ATI or dimethylaluminum isopropoxide (DMAI). [17][18][19][20] DMAI is an alumina CVD precursor which has several advantages over ATI such as a significantly higher vapor pressure; it is liquid at room temperature, has a long shelf-life and allows processing of alumina films at T d as low as 150 1C. 17,18,21 Scanning electron microscopy (SEM) and elemental analyses (electron probe micro analysis, EPMA and X-ray photoelectron spectroscopy, XPS) of the amorphous alumina films revealed different microstructures and chemical compositions depending on both the nature of the precursor and the deposition temperature.…”

Section: Introductionmentioning

confidence: 99%

Atomic scale structure of amorphous aluminum oxyhydroxide, oxide and oxycarbide films probed by very high field²⁷Al nuclear magnetic resonance

Phys. Chem. Chem. Phys.

Sarou‐Kanian

Florian

et al. 2017

The atomic scale structure of aluminum in amorphous alumina films processed by direct liquid injection chemical vapor deposition from aluminum tri-isopropoxide (ATI) and dimethyl isopropoxide (DMAI) is investigated by solid-state Al nuclear magnetic resonance (SSNMR) using a very high magnetic field of 20.0 T. This study is performed as a function of the deposition temperature in the range 300-560 °C, 150-450 °C, and 500-700 °C, for the films processed from ATI, DMAI (+HO), and DMAI (+O), respectively. While the majority of the films are composed of stoichiometric aluminum oxide, other samples are partially or fully hydroxylated at low temperature, or contain carbidic carbon when processed from DMAI above 500 °C. The quantitative analysis of the SSNMR experiments reveals that the local structure of these films is built from AlO, AlO, AlO and Al(O,C) units with minor proportions of the 6-fold aluminum coordination and significant amounts of oxycarbides in the films processed from DMAI (+O). The aluminum coordination distribution as well as the chemical shift distribution indicate that the films processed from DMAI present a higher degree of structural disorder compared to the films processed from ATI. Hydroxylation leads to an increase of the 6-fold coordination resulting from the trend of OH groups to integrate into AlO units. The evidence of an additional environment in films processed from DMAI (+O) by Al SSNMR and first-principle NMR calculations on AlC and AlOC crystal structures supports that carbon is located in Al(O,C) units. The concentration of this coordination environment strongly increases with increasing process temperature from 600 to 700 °C favoring a highly disordered structure and preventing from crystallizing into γ-alumina. The obtained results are a valuable guide to the selection of process conditions for the CVD of amorphous alumina films with regard to targeted applications.