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Title: HfO{sub 2} high-k dielectrics grown on (100)Ge with ultrathin passivation layers: Structure and interfacial stability

Abstract

We have investigated the growth of HfO{sub 2} thin films on (100)Ge by molecular beam epitaxy. By means of transmission electron microscopy, the structural characteristics of the films grown on clean Ge surfaces are compared with those grown on passivation layers of GeO{sub x} and GeO{sub x}N{sub y}. The interface was found to be very flat and thin, with an interfacial layer one or two monolayer thick. However, traces of Ge in the oxide have been detected when deposited on either one of the interfacial layers, which can be explained by the instability of the interfacial layers grown with an atomic oxygen/nitrogen beam, prior to the HfO{sub 2} deposition.

Authors:
; ; ; ;  [1];  [2];  [2];  [3]
  1. Institute of Physics of Complex Matter, Ecole Polytechnique Federal de Lausanne, CH-1015 Lausanne, Switzerland and Advanced Materials and Metrology, MosBeam Foundation, PSE, CH-1015 Lausanne (Switzerland)
  2. (Switzerland)
  3. (Greece)
Publication Date:
OSTI Identifier:
20706442
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 87; Journal Issue: 22; Other Information: DOI: 10.1063/1.2137897; (c) 2005 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CRYSTAL GROWTH; DEPOSITION; DIELECTRIC MATERIALS; GERMANIUM; HAFNIUM OXIDES; INSTABILITY; INTERFACES; LAYERS; MOLECULAR BEAM EPITAXY; NITROGEN; OXYGEN; PASSIVATION; SEMICONDUCTOR MATERIALS; STABILITY; SURFACES; THIN FILMS; TRANSMISSION ELECTRON MICROSCOPY

Citation Formats

Seo, J.W., Dieker, Ch., Locquet, J.-P., Mavrou, G., Dimoulas, A., Institute of Physics of Complex Matter, Ecole Polytechnique Federal de Lausanne, CH-1015 Lausanne, IBM Research GmbH, Zurich Research Laboratory, CH-8803 Rueschlikon, and MBE Laboratory, Institute of Materials Science, NCSR DEMOKRITOS, 153 10, Athens. HfO{sub 2} high-k dielectrics grown on (100)Ge with ultrathin passivation layers: Structure and interfacial stability. United States: N. p., 2005. Web. doi:10.1063/1.2137897.
Seo, J.W., Dieker, Ch., Locquet, J.-P., Mavrou, G., Dimoulas, A., Institute of Physics of Complex Matter, Ecole Polytechnique Federal de Lausanne, CH-1015 Lausanne, IBM Research GmbH, Zurich Research Laboratory, CH-8803 Rueschlikon, & MBE Laboratory, Institute of Materials Science, NCSR DEMOKRITOS, 153 10, Athens. HfO{sub 2} high-k dielectrics grown on (100)Ge with ultrathin passivation layers: Structure and interfacial stability. United States. doi:10.1063/1.2137897.
Seo, J.W., Dieker, Ch., Locquet, J.-P., Mavrou, G., Dimoulas, A., Institute of Physics of Complex Matter, Ecole Polytechnique Federal de Lausanne, CH-1015 Lausanne, IBM Research GmbH, Zurich Research Laboratory, CH-8803 Rueschlikon, and MBE Laboratory, Institute of Materials Science, NCSR DEMOKRITOS, 153 10, Athens. Mon . "HfO{sub 2} high-k dielectrics grown on (100)Ge with ultrathin passivation layers: Structure and interfacial stability". United States. doi:10.1063/1.2137897.
@article{osti_20706442,
title = {HfO{sub 2} high-k dielectrics grown on (100)Ge with ultrathin passivation layers: Structure and interfacial stability},
author = {Seo, J.W. and Dieker, Ch. and Locquet, J.-P. and Mavrou, G. and Dimoulas, A. and Institute of Physics of Complex Matter, Ecole Polytechnique Federal de Lausanne, CH-1015 Lausanne and IBM Research GmbH, Zurich Research Laboratory, CH-8803 Rueschlikon and MBE Laboratory, Institute of Materials Science, NCSR DEMOKRITOS, 153 10, Athens},
abstractNote = {We have investigated the growth of HfO{sub 2} thin films on (100)Ge by molecular beam epitaxy. By means of transmission electron microscopy, the structural characteristics of the films grown on clean Ge surfaces are compared with those grown on passivation layers of GeO{sub x} and GeO{sub x}N{sub y}. The interface was found to be very flat and thin, with an interfacial layer one or two monolayer thick. However, traces of Ge in the oxide have been detected when deposited on either one of the interfacial layers, which can be explained by the instability of the interfacial layers grown with an atomic oxygen/nitrogen beam, prior to the HfO{sub 2} deposition.},
doi = {10.1063/1.2137897},
journal = {Applied Physics Letters},
number = 22,
volume = 87,
place = {United States},
year = {Mon Nov 28 00:00:00 EST 2005},
month = {Mon Nov 28 00:00:00 EST 2005}
}
  • A high-quality high-κ/Ge interface has been achieved by combining molecule beam epitaxy grown Ge epitaxial layer and in-situ deposited high κ dielectric. The employment of Ge epitaxial layer has sucessfully buried and/or removed the residue of unfavorable carbon and native oxides on the chemically cleaned and ultra-high vacuum annealed Ge(100) wafer surface, as studied using angle-resolved x-ray photoelectron spectroscopy. Moreover, the scanning tunneling microscopy analyses showed the significant improvements in Ge surface roughness from 3.5 Å to 1 Å with the epi-layer growth. Thus, chemically cleaner, atomically more ordered, and morphologically smoother Ge surfaces were obtained for the subsquent deposition of highmore » κ dielectrics, comparing with those substrates without Ge epi-layer. The capacitance-voltage (C-V) characteristics and low extracted interfacial trap density (D{sub it}) reveal the improved high-κ/Ge interface using the Ge epi-layer approach.« less
  • Crystallographically oriented epitaxial Ge layers were grown on (100), (110), and (111)A GaAs substrates by in situ growth process using two separate molecular beam epitaxy chambers. The band alignment properties of atomic layer hafnium oxide (HfO{sub 2}) film deposited on crystallographically oriented epitaxial Ge were investigated using x-ray photoelectron spectroscopy (XPS). Valence band offset, {Delta}E{sub v} values of HfO{sub 2} relative to (100)Ge, (110)Ge, and (111)Ge orientations were 2.8 eV, 2.28 eV, and 2.5 eV, respectively. Using XPS data, variation in valence band offset, {Delta}E{sub V}(100)Ge>{Delta}E{sub V}(111)Ge>{Delta}E{sub V}(110)Ge, was obtained related to Ge orientation. Also, the conduction band offset, {Delta}E{submore » c} relation, {Delta}E{sub c}(110)Ge>{Delta}E{sub c}(111)Ge>{Delta}E{sub c}(100)Ge related to Ge orientations was obtained using the measured bandgap of HfO{sub 2} on each orientation and with the Ge bandgap of 0.67 eV. These band offset parameters for carrier confinement would offer an important guidance to design Ge-based p- and n-channel metal-oxide field-effect transistor for low-power application.« less
  • We investigated the passivation of In{sub 0.53}Ga{sub 0.47}As (001) surface by molecular beam epitaxy techniques. After growth of strained In{sub 0.53}Ga{sub 0.47}As on InP (001) substrate, HfO{sub 2}/Al{sub 2}O{sub 3} high-{kappa} oxide stacks have been deposited in-situ after surface reconstruction engineering. Excellent capacitance-voltage characteristics have been demonstrated along with low gate leakage currents. The interfacial density of states (D{sub it}) of the Al{sub 2}O{sub 3}/In{sub 0.53}Ga{sub 0.47}As interface have been revealed by conductance measurement, indicating a downward D{sub it} profile from the energy close to the valence band (medium 10{sup 12} cm{sup -2}eV{sup -1}) towards that close to the conductionmore » band (10{sup 11} cm{sup -2}eV{sup -1}). The low D{sub it}'s are in good agreement with the high Fermi-level movement efficiency of greater than 80%. Moreover, excellent scalability of the HfO{sub 2} has been demonstrated as evidenced by the good dependence of capacitance oxide thickness on the HfO{sub 2} thickness (dielectric constant of HfO{sub 2}{approx}20) and the remained low D{sub it}'s due to the thin Al{sub 2}O{sub 3} passivation layer. The sample with HfO{sub 2} (3.4 nm)/Al{sub 2}O{sub 3} (1.2 nm) as the gate dielectrics has exhibited an equivalent oxide thickness of {approx}0.93 nm.« less
  • The characteristics of remote plasma atomic layer deposited HfO{sub 2} on Si, which has a very thin SiO{sub 2} interlayer with and without remote plasma nitridation (RPN), have been investigated. Small amounts of N atoms were successfully incorporated by RPN pretreatment, in which the dominant emission species were excited atomic nitrogen (N{sup *}) and excited molecular nitrogen (N{sub 2}{sup *}), into a very thin SiO{sub 2} interlayer for the growth of HfO{sub 2} thin film. The thin ({approx}1.5 nm) intermediate layer containing nitrogen, which was prepared by sequential O{sub 2} and N{sub 2} remote plasma treatment of the Si substrate,more » can effectively suppress growth of the unintentional interface layer. In addition, it enhances the thermal stability and the resistance to oxygen diffusion during rapid thermal annealing. The HfO{sub 2} film containing the remote plasma nitrided SiO{sub 2} interlayer annealed at 800 deg. C showed a lower equivalent oxide thickness of {approx}1.89 nm and a lower leakage current density (3.78x10{sup -7} A cm{sup -2} at |V{sub G}-V{sub FB}|=2 V) compared to a non-nitrided sample of the same physical thickness. Also, we compared the characteristics of HfO{sub 2} films annealed in two different ambient environments, N{sub 2} and O{sub 2}.« less