Characterization of plasma-enhanced atomic layer deposition of Al2O3 using dimethylaluminum isopropoxide

Abstract

In this research, Al2O3 films were grown by remote plasma-enhanced atomic layer deposition using a nonpyrophoric precursor, dimethylaluminum isopropoxide (DMAI), and oxygen plasma. After optimization, the growth rate was determined to be ∼1.5 Å/cycle within a growth window of 25–220 °C; the higher growth rate than reported for thermal atomic layer deposition was ascribed to the higher reactivity of the plasma species compared with H2O and the adsorption of active oxygen at the surface, which was residual from the oxygen plasma exposure. Both effects enhance DMAI chemisorption and increase the saturation density. In addition, a longer oxygen plasma time was required at room temperature to complete the reaction and decrease the carbon contamination below the detection limit of x-ray photoemission spectroscopy. The properties of the subsequent Al2O3 films were measured for different temperatures. When deposited at 25 °C and 200 °C, the Al2O3 films demonstrated a single Al-O bonding state as measured by x-ray photoemission spectroscopy, a similar band gap of 6.8±0.2 eV as determined by energy loss spectroscopy, a similar index of refraction of 1.62±0.02 as determined by spectroscopic ellipsometry, and uniform growth with a similar surface roughness before and after growth as confirmed by atomic force microscopy. However, the room temperature deposited Al2O3 films had a lower mass density (2.7 g/cm3 compared with 3.0 g/cm3) and a higher atomic ratio of O to Al (2.1 compared with 1.6) as indicated by x-ray reflectivity and Rutherford backscattering spectroscopy, respectively.

Surface band bending and band alignment of plasma enhanced atomic layer deposited dielectrics on Ga- and N-face gallium nitride

“…A previous study from our group reported the band gap of PEALD Al 2 O 3 as 6.7 6 0.1 eV, which was determined from XPS O 1s energy loss spectroscopy. 12 The result is consistent with other results. 33,34 Using 6.7 eV as the band gap of the Al 2 O 3 films, the respective CBO was $1.2 and 1.4 eV for Al 2 O 3 on Ga-and N-face GaN, respectively.…”

“…The PEALD system has been discussed in detail elsewhere. 12 The precursors used for HfO 2 48,90, and 33 C to provide sufficient vapor pressure for PEALD deposition. The delivery line temperatures were maintained at $20 C higher than that of the specific bubbler to prevent precursor condensation.…”

“…The delivery line temperatures were maintained at $20 C higher than that of the specific bubbler to prevent precursor condensation. The PEALD growth rate for HfO 2 , Al 2 O 3 , and SiO 2 films was $1.4 Å /cycle, $1.5 Å /cycle, and $0.5 Å /cycle at respective substrate temperatures of $220 C, $180 C, 12 and $200 C. After dielectric growth, samples were annealed in N 2 ambient at 600 C for 30 min.…”

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

“…Dimethylaluminum isopropoxide (DMAI) was proposed by a few groups as an alternative CVD precursor to produce alumina films using evaporation or bubbling systems . DMAI was also tested for atomic layer deposition (ALD) of alumina in a few instances . This molecule consists of an Al atom linked to two methyl and one isopropyl groups, and has an intermediate structure between ATI and TMA.…”

In situ photoelectron spectroscopic characterization of c-BN films deposited via plasma enhanced chemical vapor deposition employing fluorine chemistry

“…3, was used to estimate the onset of the bulk plasmon relative to the center of the 1s peak. Previous studies have demonstrated that the bandgap of a material can be deduced by determining the position of the bulk plasmon onset relative to the core level peak [34,35]. This analysis indicated a bandgap of 6.2±0.2 eV.…”