Atomic Layer Deposition of Gd2O3 and Dy2O3: A Study of the ALD Characteristics and Structural and Electrical Properties

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• 作者：Ke Xu ; Ramdurai Ranjith ; Apurba Laha ; Harish Parala ; Andrian P. Milanov ; Roland A. Fischer ; Eberhard Bugiel ; J眉rgen Feydt ; Stefan Irsen ; Teodor Toader ; Claudia Bock ; Detlef Rogalla ; Hans-J枚rg Osten ; Ulrich Kunze ; Anjana Devi
• 刊名：Chemistry of Materials
• 出版年：2012
• 出版时间：February 28, 2012
• 年：2012
• 卷：24
• 期：4
• 页码：651-658
• 全文大小：495K
• 年卷期：v.24,no.4(February 28, 2012)
• ISSN：1520-5002

文摘

Gd₂O₃ and Dy₂O₃ thin films were grown by atomic layer deposition (ALD) on Si(100) substrates using the homoleptic rare earth guanidinate based precursors, namely, tris(N,N鈥?diisopropyl-2-dimethylamido-guanidinato)gadolinium(III) [Gd(DPDMG)₃] (1) and tris(N,N鈥?diisopropyl-2-dimethylamido-guanidinato)dysprosium(III) [Dy(DPDMG)₃] (2), respectively. Both complexes are volatile and exhibit high reactivity and good thermal stability, which are ideal characteristics of a good ALD precursor. Thin Gd₂O₃ and Dy₂O₃ layers were grown by ALD, where the precursors were used in combination with water as a reactant at reduced pressure at the substrate temperature ranging from 150 掳C to 350 掳C. A constant growth per cycle (GPC) of 1.1 脜 was obtained at deposition temperatures between 175 and 275 掳C for Gd₂O₃, and in the case of Dy₂O_3, a GPC of 1.0 脜 was obtained at 200鈥?75 掳C. The self-limiting ALD growth characteristics and the saturation behavior of the precursors were confirmed at substrate temperatures of 225 and 250 掳C within the ALD window for both Gd₂O₃ and Dy₂O₃. Thin films were structurally characterized by grazing incidence X-ray diffraction (GI-XRD), atomic force microscopy (AFM), and transmission electron microscopy (TEM) analyses for crystallinity and morphology. The chemical composition of the layer was examined by Rutherford backscattering (RBS) analysis and Auger electron spectroscopy (AES) depth profile measurements. The electrical properties of the ALD grown layers were analyzed by capacitance鈥搗oltage (C鈥?i>V) and current鈥搗oltage (I鈥?i>V) measurements. Upon subjection to a forming gas treatment, the ALD grown layers show promising dielectric behavior, with no hysteresis and reduced interface trap densities, thus revealing the potential of these layers as high-k oxide for application in complementary metal oxide semiconductor based devices.

Keywords:

atomic layer deposition; rare earth oxides; structure; morphology; electrical properties