Atomic Layer Deposition of Y2O3 Using Tris(butylcyclopentadienyl)yttrium and Water

• Published in: Russian microelectronics Vol. 48; no. 1; pp. 1 - 12
• Main Authors: Abdulagatov, A. I., Amashaev, R. R., Ashurbekova, Kr. N., Ramazanov, Sh. M., Palchaev, D. K., Maksumova, A. M., Rabadanov, M. Kh, Abdulagatov, I. M.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 2019; Springer Nature B.V
• Subjects: Aluminum oxide; Atomic layer epitaxy; Backscattering; Bulk density; Chemical vapor deposition; Electrical Engineering; Engineering; Film growth; Microbalances; Organic chemistry; Photoelectrons; Protective coatings; Quartz crystals; Refractivity; Rutherford backscattering spectroscopy; Spectrum analysis; Surface reactions; Surface stability; Thermal stability; X ray photoelectron spectroscopy; Yttrium oxide
• ISSN: 1063-7397; 1608-3415
• DOI: 10.1134/S1063739719010025

In this work, atomic-layer deposition (ALD) of yttrium oxide (Y
2
O
3
) was demonstrated using tris(butylcyclopentadienyl)yttrium (Y(CpBut)
3
) and H
2
O . Yttrium precursor showed thermal stability and a high reactivity in surface reactions with H
2
O. In situ monitoring of the deposition process by quartz crystal microbalance (QCM) showed that the growth of oxide is accompanied by the absorption of water into the bulk of the film, which can lead to chemical vapor deposition (CVD) type processes. Reducing amount of dosed water as well as purge time extension during ALD cycling allow to mitigate the CVD effects. The Y
2
O
3
film growth rate 230°C varied depending on the number of cycles and had maximum value of 1.7 Å/cycle. The films obtained at 230°C had a cubic polycrystalline structure with an average density of 96% of the Y
2
O
3
bulk density. The X-ray photoelectron spectroscopy (XPS) measurements showed a carbon impurity level below the detections limit (~0.2 at %). The O/Y atomic concentration ratio estimated by Rutherford backscattering spectroscopy (RBS) was ~1.58. As deposited Y
2
O
3
films had a refractive index of 1.85 (at 632.8 nm), whereas with protective ALD Al
2
O
3
film, the refractive index was 1.73.