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Title: Thin Film Solid-State Reactions Forming Carbides as Contact Materials for Carbon-Containing Semiconductors

Abstract

Metal carbides are good candidates to contact carbon-based semiconductors (SiC, diamond, and carbon nanotubes). Here, we report on an in situ study of carbide formation during the solid-state reaction between thin films. The solid-state reaction was examined between 11 transition metals (W, Mo, Fe, Cr, V, Nb, Mn, Ti, Ta, Zr, and Hf) and an amorphous carbon layer. Capping layers (C or TiN) of different thicknesses were applied to prevent oxidation. Carbide formation is evidenced for nine metals and the phases formed have been identified (for a temperature ranging from 100 to 1100 C). W first forms W{sub 2}C and then WC; Mo forms Mo{sub 2}C; Fe forms Fe{sub 3}C; Cr first forms metastable phases Cr{sub 2}C and Cr{sub 3}C{sub 2-x}, and finally forms Cr{sub 3}C{sub 2}; V forms VC{sub x}; Nb transforms into Nb{sub 2}C followed by NbC; Ti forms TiC; Ta first forms Ta{sub 2}C and then TaC; and Hf transforms into HfC. The activation energy for the formation of the various carbide phases has been obtained by in situ x-ray diffraction.

Authors:
; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
930660
Report Number(s):
BNL-81142-2008-JA
Journal ID: ISSN 0021-8979; JAPIAU; TRN: US200901%%19
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 101
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; TRANSITION ELEMENT COMPOUNDS; CARBIDES; CARBON; THIN FILMS; SEMICONDUCTOR DEVICES; ELECTRIC CONTACTS; ACTIVATION ENERGY; national synchrotron light source

Citation Formats

Leroy,W., Detavernier, C., Van Meirhaeghe, R., and Lavoie, C. Thin Film Solid-State Reactions Forming Carbides as Contact Materials for Carbon-Containing Semiconductors. United States: N. p., 2007. Web. doi:10.1063/1.2561173.
Leroy,W., Detavernier, C., Van Meirhaeghe, R., & Lavoie, C. Thin Film Solid-State Reactions Forming Carbides as Contact Materials for Carbon-Containing Semiconductors. United States. doi:10.1063/1.2561173.
Leroy,W., Detavernier, C., Van Meirhaeghe, R., and Lavoie, C. Mon . "Thin Film Solid-State Reactions Forming Carbides as Contact Materials for Carbon-Containing Semiconductors". United States. doi:10.1063/1.2561173.
@article{osti_930660,
title = {Thin Film Solid-State Reactions Forming Carbides as Contact Materials for Carbon-Containing Semiconductors},
author = {Leroy,W. and Detavernier, C. and Van Meirhaeghe, R. and Lavoie, C.},
abstractNote = {Metal carbides are good candidates to contact carbon-based semiconductors (SiC, diamond, and carbon nanotubes). Here, we report on an in situ study of carbide formation during the solid-state reaction between thin films. The solid-state reaction was examined between 11 transition metals (W, Mo, Fe, Cr, V, Nb, Mn, Ti, Ta, Zr, and Hf) and an amorphous carbon layer. Capping layers (C or TiN) of different thicknesses were applied to prevent oxidation. Carbide formation is evidenced for nine metals and the phases formed have been identified (for a temperature ranging from 100 to 1100 C). W first forms W{sub 2}C and then WC; Mo forms Mo{sub 2}C; Fe forms Fe{sub 3}C; Cr first forms metastable phases Cr{sub 2}C and Cr{sub 3}C{sub 2-x}, and finally forms Cr{sub 3}C{sub 2}; V forms VC{sub x}; Nb transforms into Nb{sub 2}C followed by NbC; Ti forms TiC; Ta first forms Ta{sub 2}C and then TaC; and Hf transforms into HfC. The activation energy for the formation of the various carbide phases has been obtained by in situ x-ray diffraction.},
doi = {10.1063/1.2561173},
journal = {Journal of Applied Physics},
number = ,
volume = 101,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • Metal carbides are good candidates to contact carbon-based semiconductors (SiC, diamond, and carbon nanotubes). Here, we report on an in situ study of carbide formation during the solid-state reaction between thin Ti or Mo films and C substrates. Titanium carbide (TiC) was previously reported as a contact material to diamond and carbon nanotubes. However, the present study shows two disadvantages for the solid-state reaction of Ti and C. First, because Ti reacts readily with oxygen, a capping layer should be included to enable carbide formation. Second, the TiC phase can exist over a wide range of composition (about 10%, i.e.,more » from Ti{sub 0.5}C{sub 0.5} to Ti{sub 0.6}C{sub 0.4}), leading to significant variations in the properties of the material formed. The study of the Mo-C system suggests that molybdenum carbide (Mo{sub 2}C) is a promising alternative, since the phase shows a lower resistivity (about 45% lower than for TiC), the carbide forms below 900 {sup o}C, and its formation is less sensitive to oxidation as compared with the Ti-C system. The measured resistivity for Mo{sub 2}C is p=59 {mu}{Omega} cm, and from kinetic studies an activation energy for Mo{sub 2}C formation of E{sub a}=3.15+/-0.15 eV was obtained.« less
  • The solid state reaction between a thin (30 nm) Ir film and different Si substrates (p-type Si(1 0 0), n- and p-type Si(1 1 1), silicon on insulator (SOI) and polycrystalline Si) was studied using a combination of in situ X-ray diffraction (XRD), in situ sheet resistance and laser light scattering measurements. No significant influence of either the dopants or the substrate orientation was detected as a phase formation sequence of IrSi, Ir{sub 3}Si{sub 4},Ir{sub 3}Si{sub 5} and IrSi{sub 3} was found for all samples. The presence of a thin (<4 nm) amorphous IrSi film at room temperature and itsmore » subsequent crystallization could be deduced from the appearance of a broad semi-amorphous diffraction peak in the XRD spectrum around 400 C. The results were verified using ex situ Rutherford Backscattering Spectroscopy, Scanning Electron Microscopy and 4-point probe measurements on quenched samples. The activation energy of the crystallization process and the silicide growth was determined using a Kissinger analysis on ramp anneals with different ramp rates. In addition, the influence of up to 25 volumetric % (20.5 atomic %) of Ir to the silicide formation in the Ni/Si system was studied on SOI and polycrystalline Si substrates. In the presence of Ir, the temperature range over which the low resistivity NiSi exists, is reduced both through an increase in formation temperature and an earlier consumption by the formation of NiSi{sub 2}. After the heat treatment, a continuous distribution of Ir throughout the NiSi{sub 2} phase was detected using X-ray photoelectron spectroscopy depth profiling. A low sheet resistance of < 20 {Omega}/{open_square} was maintained on both substrates up to 900 C.« less
  • Solid-state diffusion bonding of carbon-carbon (C-C) composites by using boride and carbide interlayers has been investigated. The interlayer materials used in this study were single-phase borides (TiB[sub 2] or ZrB[sub 2]), eutectic mixtures of borides and carbides (ZrB[sub 2] + ZrC or TiB[sub 2] + B[sub 4]C), and mixtures of TiB[sub 2] + SiC + B[sub 4]C produced insitu by chemical reactions between B[sub 4]C, Ti, and Si or between TiC, Si, and B. The double-notch shear strengths of the joints produced by solid-state reaction sintering of B[sub 4]C + Ti + Si interlayers were much higher than those ofmore » joints produced with other interlayers. The maximum strength was achieved for C-C specimens bonded at 2,000 C with a 2:1:1 mole ratio of Ti, Si, and B[sub 4]C powders. The reaction products identified in the interlayers, after joining, were TiB[sub 2], SiC, and TiC. The joint shear strength increased with the test temperature, from 8.99 MPa at room temperature to an average value of 14.51 MPa at 2,000 C.« less