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Title: Synthesis of cubic boron nitride films with mean ion energies of a few eV

Abstract

The lowest threshold energy of ion bombardment for cubic boron nitride (cBN) film deposition is presented. cBN films are prepared on positively biased Si (100) substrates from boron trifluoride (BF{sub 3}) gas in the high-density source region of an inductively coupled plasma with mean ion impact energies from 45 down to a few eV or less. The great decrease in the threshold ion energy is mainly attributed to specific chemical effects of fluorine as well as high ion-to-boron flux ratios. The results show evidence for the existence of a way to deposit cBN films through quasistatic chemical processes under ultralow-energy ion impact.

Authors:
; ; ;  [1];  [2];  [2];  [2]
  1. Department of Applied Science for Electronics and Materials, Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka 816-8580, Japan and Department of Engineering, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0FA (United Kingdom)
  2. (Japan)
Publication Date:
OSTI Identifier:
20982662
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 101; Journal Issue: 3; Other Information: DOI: 10.1063/1.2431401; (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; BORON; BORON FLUORIDES; BORON NITRIDES; CRYSTAL GROWTH; DEPOSITION; DEPOSITS; EV RANGE 01-10; FLUORINE; ION BEAMS; PLASMA; SUBSTRATES; SYNTHESIS; THIN FILMS; THRESHOLD ENERGY

Citation Formats

Teii, Kungen, Yamao, Ryota, Yamamura, Toshifumi, Matsumoto, Seiichiro, Department of Applied Science for Electronics and Materials, Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka 816-8580, Advanced Materials Laboratory, National Institute for Inorganic Materials, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, and Ceramic Forum Co. Ltd., 1-6-6 Taitoh, Taitoh-ku, Tokyo 110-0016. Synthesis of cubic boron nitride films with mean ion energies of a few eV. United States: N. p., 2007. Web. doi:10.1063/1.2431401.
Teii, Kungen, Yamao, Ryota, Yamamura, Toshifumi, Matsumoto, Seiichiro, Department of Applied Science for Electronics and Materials, Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka 816-8580, Advanced Materials Laboratory, National Institute for Inorganic Materials, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, & Ceramic Forum Co. Ltd., 1-6-6 Taitoh, Taitoh-ku, Tokyo 110-0016. Synthesis of cubic boron nitride films with mean ion energies of a few eV. United States. doi:10.1063/1.2431401.
Teii, Kungen, Yamao, Ryota, Yamamura, Toshifumi, Matsumoto, Seiichiro, Department of Applied Science for Electronics and Materials, Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka 816-8580, Advanced Materials Laboratory, National Institute for Inorganic Materials, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, and Ceramic Forum Co. Ltd., 1-6-6 Taitoh, Taitoh-ku, Tokyo 110-0016. Thu . "Synthesis of cubic boron nitride films with mean ion energies of a few eV". United States. doi:10.1063/1.2431401.
@article{osti_20982662,
title = {Synthesis of cubic boron nitride films with mean ion energies of a few eV},
author = {Teii, Kungen and Yamao, Ryota and Yamamura, Toshifumi and Matsumoto, Seiichiro and Department of Applied Science for Electronics and Materials, Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka 816-8580 and Advanced Materials Laboratory, National Institute for Inorganic Materials, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 and Ceramic Forum Co. Ltd., 1-6-6 Taitoh, Taitoh-ku, Tokyo 110-0016},
abstractNote = {The lowest threshold energy of ion bombardment for cubic boron nitride (cBN) film deposition is presented. cBN films are prepared on positively biased Si (100) substrates from boron trifluoride (BF{sub 3}) gas in the high-density source region of an inductively coupled plasma with mean ion impact energies from 45 down to a few eV or less. The great decrease in the threshold ion energy is mainly attributed to specific chemical effects of fluorine as well as high ion-to-boron flux ratios. The results show evidence for the existence of a way to deposit cBN films through quasistatic chemical processes under ultralow-energy ion impact.},
doi = {10.1063/1.2431401},
journal = {Journal of Applied Physics},
number = 3,
volume = 101,
place = {United States},
year = {Thu Feb 01 00:00:00 EST 2007},
month = {Thu Feb 01 00:00:00 EST 2007}
}
  • Significant ion irradiation is needed during growth to synthesize cubic boron nitride (cBN) films. This results in large film stresses, which have limited cBN film thicknesses to only a few hundred nm and represents a significant barrier in the development of cBN film technology. Using a new hybrid deposition technique, we have synthesized cubic BN films up to 700 nm (0.7 {mu}m) thick. A compositional and structural analysis of the films using several standard characterization techniques confirms that relatively thick polycrystalline films with a high cBN content were synthesized. Thicker cBN films enable hardness measurements to be undertaken without majormore » substrate effects. Nanoindentation measurements yield hardness values for the cubic BN films up to 60{endash}70 GPa, which are greater than values measured for bulk cBN. The measured elastic modulus was observed to be lower than the bulk, and this can be accounted for by an elastic deformation of the silicon substrate. The mechanical properties of the cubic BN films are discussed with reference to other ultrahard thin films such as diamond and diamondlike carbon. {copyright} {ital 1997 American Institute of Physics.}« less
  • We present high-resolution transmission electron-microscopic observations of the [ital sp][sup 2]-bonded material that remains with the [ital sp][sup 3]-bonded cubic boron nitride (cBN) in films grown by ion-assisted deposition. These observations show regions of [ital sp][sup 2]-bonded material that are in a three-layer stacking configuration rather than the two-layer configuration of hexagonal boron nitride. Measurement of the lattice fringe angles shows that the observed three-layer stacking is consistent with the metastable, rhombohedral structure (rBN). Significantly, rBN allows for a diffusionless pathway for cBN synthesis under high pressure, unlike the high-activation-energy route that is required to directly convert the hexagonal phasemore » to cBN. This low-energy pathway is considered in relation to recent work in the literature indicating that ion-induced compressive stress plays a critical role in the synthesis of thin-film cBN.« less
  • This paper deals with the synthesis of cubic phase of boron nitride on Si (100) wafers using electron beam evaporator. Four sets of samples have been deposited by varying substrate temperature and the deposition time. Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), X-ray Photoelectron Spectroscopy (XPS), and Fourier Transform Infrared Spectroscopy (FTIR) techniques have been used to determine the structure and composition of the films deposited. It was found that deposition at substrate temperature of 400 deg. C and for a period of one hour yielded high quality cubic boron nitride films.
  • We have investigated how ion irradiation can selectively promote formation of dense [ital sp][sup 3]-bonded cubic [ital c]BN over the graphite-like [ital sp][sup 2]-bonded phases. Experiments used ion-assisted pulsed laser deposition in which either the ion mass (m[sub ion]) or ion energy (E) was varied in conjunction with ratio of ion flux to depositing atom flux (J/a). For a fixed ion energy and mass, there is a critical J/a above which [ital c]BN formation is initiated, a window of J/a values in which large [ital c]BN percentages are obtained, and a point at which J/a is so large that themore » resputter and deposition rates balance and there is no net film deposition, in agreement with Kester and Messier. As do Kester and Messier, we find that [ital c]BN formation is controlled by a combination of experimental parameters that scale with the momentum of the ions. However, unlike Kester and Messier, we do not find that [ital c]BN formation scales with the maximum momentum that can be transferred in a single binary collision, as either incorrectly formulated by Targove and Macleod and used by Kester and Messier, or as correctly formulated. Instead we observe that [ital c]BN formation best scales with the total momentum of the incident ions, (m[sub ion]E)[sup 1/2]. We also consider the mechanistic origins of this (m[sub ion]E)[sup 1/2] dependence. Computer simulations of the interaction of ions with BN show that [ital c]BN formation cannot be simply scaled to parameters such as the number of atomic displacements or the number of vacancies produced by the ion irradiation. A critical examination of the literature shows that none of the proposed models satisfactorily accounts for the observed (m[sub ion]E)[sup 1/2] dependence. We present a quantitative model that describes the generation of stress during ion-assisted film growth.« less
  • In addition, the IR-active [ital c]-BN mode narrows considerably as the deposition temperature increases, suggesting that the [ital c]-BN material has fewer defects or larger grain size. It is found that films with a high [ital c]-BN percentage are deposited only in a narrow window of ion/atom arrival values that are near unity at beam energies between 800 and 1200 eV. Below this window the deposited films have a low [ital c]-BN percentage, and above this window the deposited film is completely resputtered. Using FTIR analysis, it is found that the [ital c]-BN percentage in these samples is dependent uponmore » growth time. The initial deposit is essentially all [ital sp][sup 2]-bonded material and [ital sp][sup 3]-bonded material forms above this layer. Consistently, cross-section TEM samples reveal this layer to consist of an amorphous BN layer ([similar to]30 A thick) directly on the Si substrate followed by highly oriented turbostratic BN ([similar to]300 A thick) and finally the [ital c]-BN layer. The [ital h]-BN/[ital t]-BN interfacial layer is oriented with the 002 basal planes perpendicular to the plane of the substrate. Importantly, the position of the [ital c]-BN IR phonon changes with growth time. Initially this mode appears near 1130 cm[sup [minus]1] and decreases with growth time to a constant value of 1085 cm[sup [minus]1]. Since in bulk [ital c]-BN the IR mode appears at 1065 cm[sup [minus]1], a large compressive stress induced by the ion bombardment is suggested. Possible mechanisms are commented on for the conversion process to [ital c]-BN based upon the results.« less