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Title: Effect of arc suppression on the physical properties of low temperature dc magnetron sputtered tantalum thin films

Abstract

Arcing is a common phenomenon in the sputtering process. Arcs and glow discharges emit electrons which may influence the physical properties of films. This article reports the properties of tantalum (Ta) thin films prepared by continuous dc magnetron sputtering in normal and arc-suppression modes. The substrate temperature was varied in the range of 300-673 K. The tantalum films were {approx}1.8 {mu}m thick and have good adherence to 316 stainless steel and single-crystal silicon substrates. The phase of the Ta thin film determines the electrical and tribological properties. The films deposited at 300 K using both methods were crystallized in a tetragonal structure ({beta} phase) with a smooth surface (grain size of {approx}10 nm) and exhibited an electrical resistivity of {approx}194 {mu}{omega} cm and a hardness of {approx}20 GPa. When the substrate temperature was 473 K and higher, the arc-suppression mode appears to influence the films to crystallize in the {alpha} phase with a grain size of {approx}40 nm, whereas the normal power mode gave mixed phases {beta} and {alpha} beyond 473 K, the arc-suppression mode yields larger grain sizes in the Ta thin films and the hardness decreases. These changes in the physical properties in arc-suppression mode are attributed tomore » either the change in plasma characteristics or the energetic particle bombardment onto the substrate, or both.« less

Authors:
; ; ;  [1];  [2]
  1. Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India)
  2. (India)
Publication Date:
OSTI Identifier:
20979397
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Vacuum Science and Technology. A, International Journal Devoted to Vacuum, Surfaces, and Films; Journal Volume: 25; Journal Issue: 2; Other Information: DOI: 10.1116/1.2699296; (c) 2007 American Vacuum Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ADHESION; CRYSTALLIZATION; DEPOSITION; ELECTRIC CONDUCTIVITY; ELECTRONS; GLOW DISCHARGES; GRAIN SIZE; HARDNESS; INHIBITION; MAGNETRONS; MONOCRYSTALS; SILICON; SPUTTERING; STAINLESS STEELS; SUBSTRATES; TANTALUM; TEMPERATURE RANGE 0065-0273 K; THIN FILMS; TRIBOLOGY

Citation Formats

Subrahmanyam, A., Valleti, Krishna, Joshi, Srikant V., Sundararajan, G., and ARCI, Balapur, Hyderabad 500005. Effect of arc suppression on the physical properties of low temperature dc magnetron sputtered tantalum thin films. United States: N. p., 2007. Web. doi:10.1116/1.2699296.
Subrahmanyam, A., Valleti, Krishna, Joshi, Srikant V., Sundararajan, G., & ARCI, Balapur, Hyderabad 500005. Effect of arc suppression on the physical properties of low temperature dc magnetron sputtered tantalum thin films. United States. doi:10.1116/1.2699296.
Subrahmanyam, A., Valleti, Krishna, Joshi, Srikant V., Sundararajan, G., and ARCI, Balapur, Hyderabad 500005. Thu . "Effect of arc suppression on the physical properties of low temperature dc magnetron sputtered tantalum thin films". United States. doi:10.1116/1.2699296.
@article{osti_20979397,
title = {Effect of arc suppression on the physical properties of low temperature dc magnetron sputtered tantalum thin films},
author = {Subrahmanyam, A. and Valleti, Krishna and Joshi, Srikant V. and Sundararajan, G. and ARCI, Balapur, Hyderabad 500005},
abstractNote = {Arcing is a common phenomenon in the sputtering process. Arcs and glow discharges emit electrons which may influence the physical properties of films. This article reports the properties of tantalum (Ta) thin films prepared by continuous dc magnetron sputtering in normal and arc-suppression modes. The substrate temperature was varied in the range of 300-673 K. The tantalum films were {approx}1.8 {mu}m thick and have good adherence to 316 stainless steel and single-crystal silicon substrates. The phase of the Ta thin film determines the electrical and tribological properties. The films deposited at 300 K using both methods were crystallized in a tetragonal structure ({beta} phase) with a smooth surface (grain size of {approx}10 nm) and exhibited an electrical resistivity of {approx}194 {mu}{omega} cm and a hardness of {approx}20 GPa. When the substrate temperature was 473 K and higher, the arc-suppression mode appears to influence the films to crystallize in the {alpha} phase with a grain size of {approx}40 nm, whereas the normal power mode gave mixed phases {beta} and {alpha} beyond 473 K, the arc-suppression mode yields larger grain sizes in the Ta thin films and the hardness decreases. These changes in the physical properties in arc-suppression mode are attributed to either the change in plasma characteristics or the energetic particle bombardment onto the substrate, or both.},
doi = {10.1116/1.2699296},
journal = {Journal of Vacuum Science and Technology. A, International Journal Devoted to Vacuum, Surfaces, and Films},
number = 2,
volume = 25,
place = {United States},
year = {Thu Mar 15 00:00:00 EDT 2007},
month = {Thu Mar 15 00:00:00 EDT 2007}
}
  • Molybdenum oxide films were deposited on glass and single crystal silicon substrates held at room temperature by sputtering of molybdenum target in an oxygen partial pressure of 2xl0{sup -4} mbar. The MoO{sub 3} films were annealed in oxygen atmosphere at various temperatures in the range 473-673 K. The effect of annealing temperature on the structure, chemical binding configuration, and optical properties of the MoO{sub 3} films was studied. The X-ray diffraction studies revealed that the as-deposited MoO{sub 3} films were amorphous. It crystallizes into a layered orthorhombic phase by the post-deposition annealing at a temperature of 673 K. The Fouriermore » transform infrared spectrum of the MoO{sub 3} films annealed at 473 K exhibits the absorption bands at 560, 840 and 995 cm{sup -1} related to the active stretching modes of MoO{sub 6} octahedra. When the films annealed at 673 K the intensity of the absorption band observed at 560 cm{sup -1} diminished and the band of 995 cm{sup -1} split into two bands of 995 and 1010 cm{sup -1} which are related to the zig--zag rows of layered structure of MoO{sub 3}. The optical band gap of the as-deposited and annealed films was 3.07 and 3.20 eV respectively. The refractive index increased with increase of annealing temperature.« less
  • A study of the electrical properties and spatial distribution of the ZnO:Al (AZO) thin films prepared by dc magnetron sputtering at low deposition temperature was presented, with emphasis on the origin of the resistivity inhomogeneity across the substrate. Various growth conditions were obtained by manipulating the growth temperature T{sub S}, total pressure P{sub T}, and ion-to-neutral ratio J{sub i}/J{sub n}. The plasma characteristics such as radial ion density and floating/plasma potential distribution over the substrate were measured by Langmuir probe, while the flux and energy distribution of energetic species were estimated through Monte Carlo simulations. The crystalline, stress and electricalmore » properties of the films were found to be strongly dependent on T{sub S} and J{sub i}/J{sub n}. Under the low J{sub i}/J{sub n} (<0.3) conditions, the T{sub S} exerted a remarkable influence on film quality. The films prepared at 90 deg. C were highly compressed, exhibiting poor electrical properties and significant spatial distribution. High quality films with low stress and resistivity were produced at higher T{sub S} (200 deg. C). Similarly, at lower T{sub S} (90 deg. C), higher J{sub i}/J{sub n} ({approx}2) dramatically improved the film resistivity as well as its lateral distribution. Moreover, it indicated that the role of ion bombardment is dependent on the mechanism of dissipation of incident species. Ion bombardment is beneficial to the film growth if the energy of incident species E{sub i} is below the penetration threshold E{sub pet} ({approx}33 eV for ZnO); on the other hand, the energy subimplant mechanism would work, and the bombardment degrades the film quality when E{sub i} is over the E{sub pet}. The energetic bombardment of negative oxygen ions rather than the positives dominated the resistivity distribution of AZO films, while the nonuniform distribution of active oxygen played a secondary role which was otherwise more notable under conditions of lower T{sub S} and J{sub i}/J{sub n}.« less
  • Nanocrystalline zirconia thin films have been deposited at ambient temperature by dc magnetron sputtering on glass and quartz substrates. The crystallite size as calculated from the x-ray diffraction patterns in the films varies between 10 and 25 nm and is dependent on oxygen percentage in the sputtering gas. Interestingly, the presence of monoclinic and cubic phase is observed for the films deposited on glass at 40%, 60%, and 80% of oxygen in the sputtering gas, while those deposited on quartz showed only the monoclinic phase. Refractive index decreased with increase in percentage of oxygen in the sputter gas. Significantly, evenmore » at 100% oxygen in the sputtering gas, films of thickness of the order of 500 nm have been grown starting from the metallic Zr target. The dielectric constants were measured using the extended cavity perturbation technique at X-band frequency (8-12 GHz). The dielectric constant and loss tangent showed a very small decrease with increase in frequency but exhibited a stronger dependence on processing parameters. The dielectric constants of the films at microwave frequencies ranged between 12.16 and 22.3.« less
  • Cadmium telluride continues to be a leading candidate for the development of cost effective photovoltaics for terrestrial applications. In the present work two individual metallic targets of Cd and Te were used for the deposition of CdTe thin films on mica substrates from room temperature to 300 °C by DC reactive magnetron sputtering method. XRD patterns of CdTe thin films deposited on mica substrates exhibit peaks at 2θ = 27.7°, 46.1° and 54.6°, which corresponds to reflection on (1 1 1), (2 2 0) and (3 1 1) planes of CdTe cubic structure. The intensities of XRD patterns increases withmore » the increase of substrate temperature upto 150 °C and then it decreases at higher substrate temperatures. The conductivity of CdTe thin films measured from four probe method increases with the increase of substrate temperature. The activation energies (ΔE) are found to be decrease with the increase of substrate temperature. The optical transmittance spectra of CdTe thin films deposited on mica have a clear interference pattern in the longer wavelength region. The films have good transparency (T > 85 %) exhibiting interference pattern in the spectral region between 1200 – 2500 nm. The optical band gap of CdTe thin films are found to be in the range of 1.48 – 1.57. The refractive index, n decreases with the increase of wavelength, λ. The value of n and k increases with the increase of substrate temperature.« less
  • Highly transparent conductive Zinc Aluminum Oxide (ZAO) thin films have been deposited on glass substrates using DC reactive magnetron sputtering method. The thin films were deposited at 200 °C and post-deposition annealing from 15 to 90 min. XRD patterns of ZAO films exhibit only (0 0 2) diffraction peak, indicating that they have c-axis preferred orientation perpendicular to the substrate. Scanning electron microscopy (SEM) is used to study the surface morphology of the films. The grain size obtained from SEM images of ZAO thin films are found to be in the range of 20 - 26 nm. The minimum resistivitymore » of 1.74 × 10{sup −4} Ω cm and an average transmittance of 92% are obtained for the thin film post annealed for 30 min. The optical band gap of ZAO thin films increased from 3.49 to 3.60 eV with the increase of annealing time due to Burstein-Moss effect. The optical constants refractive index (n) and extinction coefficient (k) were also determined from the optical transmission spectra.« less