Atomic Layer Deposition of Titanium Dioxide Thin Films from Cp*Ti(OMe)₃ and Ozone

Abstract

The thermal atomic layer deposition of TiO2 from Cp*Ti(OMe)3 and ozone was studied in a 300 mm wafer reactor by quadrupole mass spectrometry (QMS). The deposited thin films were analyzed by X-ray reflectivity (XRR), X-ray photoelectron spectroscopy (XPS), grazing incident X-ray diffraction, and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The XRR and XPS measurements revealed that nearly stoichiometric TiO2 films were grown in a self-limiting growth mode. The growth per cycle increased from 0.22 Å at 235 °C to 0.29 Å at 330 °C. Films deposited on titanium nitride showed an anatase crystal structure, while films deposited on ruthenium crystallized in the rutile phase. The ToF-SIMS analysis indicated that the carbon contamination reduced to very low levels at a deposition temperature of 295 °C. The QMS studies revealed the release of MeOH during the precursor pulse. CO2 and H2O were released during the ozone pulse at a process pressure of 7 mbar. At a pressure of 3 × 10−3 mbar, the release of the Cp* ligand and the remaining OMe ligands during the ozone pulse could be observed. It was demonstrated that QMS studies can be used in a 300 mm reactor at very low pressures to study the process chemistry.

Plasma-Assisted Atomic Layer Deposition of SrTiO3: Stoichiometry and Crystallinity Studied by Spectroscopic Ellipsometry

“…26 In one of the first reports on ALD of STO, the GPC for the SrO process using Sr(C 5 i PrH 2 ) 2 (Hyper-Sr without the DME adduct) and H 2 O was also 0.11 nm/cycle. 9 The GPC of TiO 2 is comparable to those reported in the literature, with values ranging from 0.022 nm/cycle 27 to ∼0.03 nm/cycle 26 for the combination of Ti-Star and O 3 . These values show the variation in GPC reported in the literature for ALD processes employing the same precursors but developed in different equipment, showing the sensitivity of ALD processes to the varying reactor design and experimental conditions.…”

Plasma-Assisted Atomic Layer Deposition of SrTiO3: Stoichiometry and Crystallinity Study by Spectroscopic Ellipsometry

“…In one of the first reports on ALD of STO, the GPC for the SrO process using Sr(C 5 i PrH 2 ) 2 and H 2 O was also 0.11 nm/cycle (13). The GPC of TiO 2 is also comparable to results reported in literature, where values of ~0.03 nm/cycle (12) and 0.022 nm/cycle (14) were reported for the combination of TiStar and O 3 .…”

Plasma-enhanced atomic layer deposition of titania on alumina for its potential use as a hydrogen-selective membrane

“…A typical cycle time of 13 s was obtained by employing a TiCp*(OMe) 3 pulse of 2 s, an Ar purge of 3 s, a plasma step of 5 s, and an Ar purge of 3 s. It should be noted that this cycle time was optimized using planar substrates. Although some details about the reaction mechanism of ALD of TiO 2 from TiCp*(OMe) 3 and O 3 have recently been reported [18], the surface chemistry for the PE-ALD process from this titanium precursor and O 2 plasma has not been unravelled yet. However, it has been observed that during the O 2 step (a fraction of) the ligands remaining on the surface after precursor adsorption are combusted into CO 2 and H 2 O species, which were measured by mass spectrometry.…”