| AVS 64th International Symposium & Exhibition | |
| Thin Films Division | Thursday Sessions |
| Session TF+SE-ThM |
| Session: | Control, Characterization, and Modeling of Thin Films I |
| Presenter: | Rezwanur Rahman, University of Texas at Dallas |
| Authors: | R. Rahman, University of Texas at Dallas J.P. Klesko, University of Texas at Dallas A. Dangerfield, University of Texas at Dallas J.-S. Lehn, EMD Performance Materials C.L. Dezelah, EMD Performance Materials R. Kanjolia, EMD Performance Materials Y.J. Chabal, University of Texas at Dallas |
| Correspondent: | Click to Email |
Scandium oxide (Sc2O3) thin films have been thoroughly studied for their use in microelectronic devices.1–2 However, processes for the atomic layer deposition (ALD) of Sc2O3 films are scarce, and have mostly involved Sc(thd)3,1 ScCp3,1 Sc(MeCp)3,2 and Sc(amd)33 precursors. To date, the only mechanistic investigation has focused on the Sc(MeCp)3/H2O process using in-situ time-resolved quadrupole mass spectrometry to probe the Sc2O3 ALD chemistry.2
Herein, we have explored the Sc2O3 ALD using bis(methylcyclopentadienyl)3,5-dimethyl pyrazolatoscandium (Sc(MeCp)2(Me2pz)) with ozone and with D2O. This precursor reacts with hydroxyl-terminated silicon, Si(111)– SiO2–OH, at 150 °C and appears to remain thermally stable to 450 °C. Between 225 and 275 °C, there is a clear ligand exchange with ozone observed in the differential IR absorption spectra involving the formation of intermediate formate and carbonate species (1400–1600 cm-1) after each ozone pulse. A short incubation period (≤ 5 ALD cycles) is observed at 225 °C prior to the onset of steady-state ligand exchange. The signature for the formation of Si–O–Sc bonds (1240 cm–1) is clearly present after cycles 1–2 for the ozone process at 275 °C. The Sc2O3 growth is quantified by X-ray photoelectron spectroscopy (XPS) and by spectroscopic ellipsometry (SE), from which a growth rate of ~0.3–0.9 Å/cycle is extracted over the 225–275 °C temperature range.
In contrast, there is no ligand exchange observed for the D2O process within the same temperature range, although some deposition occurs. The deposition rate for the D2O process calculated by XPS and SE, is ~1.3 Å/cycle within the 225–275 °C window, which is higher than the non-uniform growth rate measured for the ozone process within that temperature range. The higher growth rate and lack of ligand exchange observed with D2O is tentatively attributed to a CVD component that dominates the film growth process.
1. Putkonen, M.; Nieminen, M.; Niinist ö, J.; Niinist ö, L.; Sajavaara,T. Chem. Mater. 2001, 13, 4701−4707.
2. Han, J. H.; Nyns, L.; Delabie, A.; Franquet, A.; Van Elshocht, S.; Adelmann, C. Chem. Mater. 2014, 26, 1404−1412.
3. de Rouffignac, P.; Yousef, A. P.; Kim, K. H.; Gordon, R. G. Electrochem. Solid-State Lett. 2006, 9, F45–F48.