Atomic Layer Deposition of AlF3 Using Trimethylaluminum and Hydrogen Fluoride

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• 作者：Younghee Lee ; Jaime W. DuMont ; Andrew S. Cavanagh ; Steven M. George
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：June 25, 2015
• 年：2015
• 卷：119
• 期：25
• 页码：14185-14194
• 全文大小：590K
• ISSN：1932-7455

文摘

The atomic layer deposition (ALD) of AlF₃ was demonstrated using trimethylaluminum (TMA) and hydrogen fluoride (HF). The HF source was HF-pyridine. In situ quartz crystal microbalance (QCM), quadrupole mass spectrometer (QMS), and Fourier transform infrared (FTIR) spectroscopy measurements were used to study AlF₃ ALD. The AlF₃ ALD film growth was examined at temperatures from 75 to 300 掳C. Both the TMA and HF reactions displayed self-limiting behavior. The maximum mass gain per cycle (MGPC) of 44 ng/(cm² cycle) for AlF₃ ALD occurred at 100 掳C. The MGPC values decreased at higher temperatures. The MGPC values were negative at T > 250 掳C when TMA and HF were able to etch the AlF₃ films. Film thicknesses were also determined using ex situ X-ray reflectivity (XRR) and spectroscopic ellipsometry (SE) measurements. The AlF₃ ALD growth rate determined by the ex situ analysis was 1.43 脜/cycle at 100 掳C. These ex situ measurements were in excellent agreement with the in situ QCM measurements. FTIR analysis monitored the growth of infrared absorbance from Al鈥揊 stretching vibrations at 500鈥?00 cm^鈥? during AlF₃ ALD. In addition, absorption peaks were observed that were consistent with AlF(CH₃)₂ and HF species on the surface after the TMA and HF exposures, respectively. X-ray photoelectron spectroscopy (XPS) and Rutherford backscattering spectrometry (RBS) measurements revealed that the deposited films were nearly stoichiometric AlF₃ with an oxygen impurity of only 鈭? at %. AlF₃ ALD may be useful for a number of applications such as ultraviolet optical films, protective coatings for the electrodes of Li ion batteries, and Lewis acid catalytic films.