Water assisted atomic layer deposition of yttrium oxide using tris(N,N′-diisopropyl-2-dimethylamido-guanidinato) yttrium(iii): process development,film characterization and functional properties |
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Authors: | Lukas Mai,Nils Boysen,Ersoy Subaş ı ,Teresa de los Arcos,Detlef Rogalla,Guido Grundmeier,Claudia Bock,Hong-Liang Lu,Anjana Devi |
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Affiliation: | Inorganic Materials Chemistry, Ruhr-University Bochum, 44801 Bochum Germany.; Werkstoffe und Nanoelektronik, Ruhr-Universität Bochum, 44801 Bochum Germany ; Macromolecular and Technical Chemistry, University of Paderborn, 33098 Paderborn Germany ; RUBION, Ruhr-University Bochum, 44801 Bochum Germany ; Mikrosystemtechnik, Ruhr-Universität Bochum, 44801 Bochum Germany ; Institute of Advanced Nanodevices, School of Microelectronics, Fudan University, Shanghai 200433 China |
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Abstract: | We report a new atomic layer deposition (ALD) process for yttrium oxide (Y2O3) thin films using tris(N,N′-diisopropyl-2-dimethylamido-guanidinato) yttrium(iii) [Y(DPDMG)3] which possesses an optimal reactivity towards water that enabled the growth of high quality thin films. Saturative behavior of the precursor and a constant growth rate of 1.1 Å per cycle confirm the characteristic self-limiting ALD growth in a temperature range from 175 °C to 250 °C. The polycrystalline films in the cubic phase are uniform and smooth with a root mean squared (RMS) roughness of 0.55 nm, while the O/Y ratio of 2.0 reveal oxygen rich layers with low carbon contaminations of around 2 at%. Optical properties determined via UV/Vis measurements revealed the direct optical band gap of 5.56 eV. The valuable intrinsic properties such as a high dielectric constant make Y2O3 a promising candidate in microelectronic applications. Thus the electrical characteristics of the ALD grown layers embedded in a metal insulator semiconductor (MIS) capacitor structure were determined which resulted in a dielectric permittivity of 11, low leakage current density (≈10−7 A cm−2 at 2 MV cm−1) and high electrical breakdown fields (4.0–7.5 MV cm−1). These promising results demonstrate the potential of the new and simple Y2O3 ALD process for gate oxide applications.A new water assisted atomic layer deposition (ALD) process was developed using the yttrium tris-guanidinate precursor which resulted in device quality thin films. |
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