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Stability of La2O3 and GeO2 passivated Ge surfaces during ALD of ZrO2 high-k dielectric |
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| Authors: | O. Bethge C. Henkel S. AbermannG. Pozzovivo M. Stoeger-PollachW.S.M. Werner J. SmolinerE. Bertagnolli |
| Affiliation: | a Institute for Solid State Electronics, Vienna University of Technology, Floragasse 7, 1040 Vienna, Austria b Austrian Institute of Technology, Energy Department, Giefinggasse 2, 1210 Vienna, Austria c USTEM, Vienna University of Technology, Wiedner Hauptstraße 8-10, 1040 Vienna, Austria d Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstraße 8, 1040 Vienna, Austria |
| Abstract: | La2O3 grown by atomic layer deposition (ALD) and thermally grown GeO2 are used to establish effective electrical surface passivations on n-type (1 0 0)-Ge substrates for high-k ZrO2 dielectrics, grown by ALD at 250 °C substrate temperature. The electrical characterization of MOS capacitors indicates an impact of the Ge-surface passivation on the interfacial trap density and the frequency dependent capacitance in the inversion regime. Lower interface trap densities can be obtained for GeO2 based passivation even though a chemical decomposition of the oxidation states occur during the ALD of ZrO2. As a consequence the formation of a ZrGeOx compound inside the ZrO2 matrix and a decline of the interfacial GeO2 are observed. The La2O3 passivation provides a stable amorphous lanthanum germanate phase at the Ge interface but also traces of Zr germanate are indicated by X-ray-Photoelectron-Spectroscopy and Transmission-Electron-Microscopy. |
| Keywords: | ALD ZrO2 La2O3 GeO2 Ge MOS capacitor |
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