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Title: Effects of plasma immersion ion nitridation on dielectric properties of HfO{sub 2}

Abstract

Plasma immersion ion nitridation is used to produce thin HfO{sub 2} films with improved thermal and electrical properties. The film composition is investigated by examining the chemical shifts of the Hf 4f, Si 2p, and N 1s core-level spectra using x-ray photoelectron spectroscopy. The improved thermal stability and interfacial microstructure are further confirmed by high-resolution cross-sectional transmission electron microscopy. Electrical studies show an equivalent oxide thickness of about 1.25 nm, a negligible hysteresis of about 5 mV, and a low fixed charge density.

Authors:
; ; ; ;  [1];  [2]
  1. Department of Electronic Engineering, Chinese University of Hong Kong, Shatin, New Territories, Hong Kong (China)
  2. (China)
Publication Date:
OSTI Identifier:
20960165
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 90; Journal Issue: 12; Other Information: DOI: 10.1063/1.2715044; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CHARGE DENSITY; CHEMICAL SHIFT; DIELECTRIC MATERIALS; DIELECTRIC PROPERTIES; HAFNIUM OXIDES; HYSTERESIS; INTERFACES; MICROSTRUCTURE; NITRIDATION; PLASMA; SEMICONDUCTOR MATERIALS; SILICON; THIN FILMS; TRANSMISSION ELECTRON MICROSCOPY; X-RAY PHOTOELECTRON SPECTROSCOPY

Citation Formats

Wang, L., Xue, K., Xu, J. B., Huang, A. P., Chu, Paul K., and Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong. Effects of plasma immersion ion nitridation on dielectric properties of HfO{sub 2}. United States: N. p., 2007. Web. doi:10.1063/1.2715044.
Wang, L., Xue, K., Xu, J. B., Huang, A. P., Chu, Paul K., & Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong. Effects of plasma immersion ion nitridation on dielectric properties of HfO{sub 2}. United States. doi:10.1063/1.2715044.
Wang, L., Xue, K., Xu, J. B., Huang, A. P., Chu, Paul K., and Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong. Mon . "Effects of plasma immersion ion nitridation on dielectric properties of HfO{sub 2}". United States. doi:10.1063/1.2715044.
@article{osti_20960165,
title = {Effects of plasma immersion ion nitridation on dielectric properties of HfO{sub 2}},
author = {Wang, L. and Xue, K. and Xu, J. B. and Huang, A. P. and Chu, Paul K. and Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong},
abstractNote = {Plasma immersion ion nitridation is used to produce thin HfO{sub 2} films with improved thermal and electrical properties. The film composition is investigated by examining the chemical shifts of the Hf 4f, Si 2p, and N 1s core-level spectra using x-ray photoelectron spectroscopy. The improved thermal stability and interfacial microstructure are further confirmed by high-resolution cross-sectional transmission electron microscopy. Electrical studies show an equivalent oxide thickness of about 1.25 nm, a negligible hysteresis of about 5 mV, and a low fixed charge density.},
doi = {10.1063/1.2715044},
journal = {Applied Physics Letters},
number = 12,
volume = 90,
place = {United States},
year = {Mon Mar 19 00:00:00 EDT 2007},
month = {Mon Mar 19 00:00:00 EDT 2007}
}
  • 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
  • We have prepared plasma enhanced atomic layer deposition HfO{sub x}N{sub y} thin films by in situ nitridation using nitrogen/oxygen mixture plasma and studied the effects of nitrogen contents and profiles on the negative bias temperature instability (NBTI). The nitrogen depth profiles and concentrations were controlled by changing the exposure sequences and the nitrogen to oxygen flow ratio, respectively. The best immunity to NBTI degradations was obtained for the nitrogen to oxygen ratio of 2:1 when nitrogen atoms are incorporated away from the high k/Si interface. We propose a dielectric degradation mechanism based on the reaction-diffusion model in which nitrogen playsmore » a role of hydrogen generator at the interface and diffusion barrier in the bulk film.« less
  • We report the effects of Ti doping on the dielectric properties of HfO{sub 2} [Hf{sub 1-x}Ti{sub x}O{sub 2} (x = 0.2-0.8)] nanoparticles at room temperature. The Hf{sub 1-x}Ti{sub x}O{sub 2} nanoparticles were synthesized by a wet chemical process. The structural and morphological properties of the derived samples were analyzed with X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and high resolution transmission electron microscopy (HRTEM). Impedance analysis was performed in pelletized samples in the frequency range of 1 MHz to 1 GHz. The obtained results were analyzed in correlation with microstructure and doping concentration in the derived samples. The averagemore » size of the Hf{sub 1-x}Ti{sub x}O{sub 2} nanoparticles is typically in the range of 4-8 nm depending on the processing temperature. The Hf{sub 1−x}Ti{sub x}O{sub 2} nanoparticles show reduction in crystallinity with the increase in Ti doping. The dielectric constants of the derived samples decrease with the increase in frequency. The ac-conductivity in the samples increases with the increase in frequency irrespective of Ti concentration and shows significant drop with the increase in Ti concentration at all frequencies.« less
  • In this work, HfO{sub 2}/La{sub 2}O{sub 3} nanolaminate films were deposited on Si substrates by plasma enhanced atomic layer deposition with in situ plasma treatment. Different annealing treatments were adopted to change films structure and performance. The upper HfO{sub 2} layers in HfO{sub 2}/La{sub 2}O{sub 3} nanolaminates were easily crystallized after annealing at 800 °C, while all the La{sub 2}O{sub 3} layers kept amorphous. X-ray photoelectron spectroscopy results indicated that LaO(OH) and La(OH){sub 3} peaks became weak, H{sub 2}O molecules in laminates evaporated during high-temperature annealing. Band diagram analysis showed that valence band offset and band gap widened after 800 °C annealing.more » Annealing, especially 800 °C annealing, had gentle effect on leakage current, but could obviously change capacitance and permittivity due to tetragonal and cubic phase formed in the HfO{sub 2} film.« less
  • The effect of the interface between Al{sub 2}O{sub 3} and HfO{sub 2} sublayers on the dielectric constant was investigated in HfO{sub 2}/Al{sub 2}O{sub 3} nanolaminate films deposited using plasma-enhanced atomic layer deposition. After annealing at 700 deg. C, the dielectric constants of the nanolaminate films with a sublayer thickness of 40 A ring or greater were the same as the calculated values for a series of capacitors consisting of amorphous Al{sub 2}O{sub 3} and monoclinic or tetragonal HfO{sub 2}. As the sublayer thickness was reduced to 10 A, the dielectric constant increased up to 17.7 because a thin Hf-O-Al mixturemore » layer, of which the number increases drastically in the nanolaminate films with thin sublayers, is formed at the interface.« less