Al₂O₃ Atomic Layer Deposition with Trimethylaluminum and Ozone Studied by in Situ Transmission FTIR Spectroscopy and Quadrupole Mass Spectrometry

Abstract

The atomic layer deposition (ALD) of Al 2 O 3 using sequential exposures of Al(CH 3 ) 3 and O 3 was studied by in situ transmission Fourier transform infrared (FTIR) spectroscopy and quadrupole mass spectrometry (QMS). The FTIR spectroscopy investigations of the surface reactions occurring during Al 2 O 3 ALD were performed on ZrO 2 particles for temperatures from 363 to 650 K. The FTIR spectra after Al(CH 3 ) 3 and ozone exposures showed that the ozone exposure removes surface AlCH 3 * species. The AlCH 3 * species were converted to AlOCH 3 * (methoxy), Al(OCHO)* (formate), Al(OCOOH)* (carbonate), and AlOH* (hydroxyl) species. The TMA exposure then removes these species and reestablishes the AlCH 3 * species. Repeating the TMA and O 3 exposures in a sequential reaction sequence progressively deposited the Al 2 O 3 ALD film as monitored by the increase in absorbance for bulk Al 2 O 3 infrared features. The identification of formate species was confirmed by separate formaldehyde adsorption experiments. The formate species were temperature dependent and were nearly absent at temperatures g650 K. QMS analysis of the gas phase species revealed that the TMA reaction produced CH 4 . The ozone reaction produced mainly CH 4 with small amounts of C 2 H 4 (ethylene), CO, and CO 2 . Transmission electron microscopy (TEM) was also used to examine the Al 2 O 3 ALD films deposited on the ZrO 2 particles. These TEM images observed conformal Al 2 O 3 ALD films with thicknesses that were consistent with an Al 2 O 3 ALD growth rate of 1.1 Å/cycle. The surface species after the O 3 exposures and the mass spectrometry results lead to a very different mechanism for Al 2 O 3 ALD growth using TMA and O 3 compared with Al 2 O 3 ALD using TMA and H 2 O.

Review—Investigation and Review of the Thermal, Mechanical, Electrical, Optical, and Structural Properties of Atomic Layer Deposited High-kDielectrics: Beryllium Oxide, Aluminum Oxide, Hafnium Oxide, and Aluminum Nitride

“…The ALD Al 2 O 3 T-FTIR spectrum (Fig. 1a) shows only a broad absorption band centered at ∼755 cm -1 that is similar in appearance to other reported FTIR spectra for Al 2 O 3 films deposited by ALD [162][163][164] and PECVD [165][166][167] methods. The broad nature of the absorption band shown in Fig.…”

“…1a is generally attributed to unresolved Al-O-Al bending (650-700 cm -1 ) and Al-O stretching (750-850 cm -1 ) bands. [162][163][164][165][166][167] Alternatively, the Al 2 O 3 FTIR absorption band in this range can be interpreted in terms of the Al coordination where the stretching modes for AlO 6 octahedra are expected at 500-750 cm -1 whereas the stretching modes for AlO 4 tetrahedra are expected at 750-850 cm -1 . 154,155 From this perspective, the broad nature for the Al-O absorption band in Fig.…”

Fabrication and surface passivation of porous 6H-SiC by atomic layer deposited films

“…However, the improvement for TiO 2 passivation is slightly smaller than that for Al 2 O 3 films due to the less quantity of O-H bonds [24,28,30,35]. After TiO 2 passivation, the porous samples a, b, c and d have a PL increase of 154%, 83.4%, 78.6% and 71.5%, respectively, as shown in Fig.…”

High efficiency CCD detectors at UV wavelengths

“…ALD enables conformal, atomic level control over film growth and allows well controlled, repeatable depositions. ALD recipes for Al 2 O 3 came from Goldstein (2008) 26 and SiO 2 from Dingemans (2011). 27 Often growth recipes required modifications to accommodate the equipment used.…”