Alumina films by sputter deposition with Ar/O2: Preparation and characterization

Bhatia, Charanjit S.; Guthmiller, G.; Spool, A.

doi:10.1116/1.576273

Cited by 49 publications

(18 citation statements)

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“…The refractive index of our films was between 1.35 and 1.40. The density was then estimated from the refractive index by a modification of the Clausius-Mosotti relation (33) to be about 2.35 g∕cm 3 , a low value in the range of densities reported in the literature for amorphous alumina (2.1-3.6 g∕cm 3 ) (19,20). A Hitachi S-4300 FEG-SEM, with a lateral resolution of 1.5 nm was used for scanning electron microscope imaging of cross sections of the coated substrate.…”

Section: Methodsmentioning

confidence: 99%

“…Certainly, the lack of crystalline order and the fact that am-Al 2 O 3 is found with a wide range of densities, complicates any study of the electronic structure. In fact, the density of am-Al 2 O 3 varies within an extremely large range, from 2.1 to 3.6 g∕cm 3 (19,20). The greatly varying density of am-Al 2 O 3 may well have been the major cause of the past debate on the coordination of oxygen around aluminum (21)(22)(23)(24)(25).…”

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confidence: 99%

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Unveiling the complex electronic structure of amorphous metal oxides

Århammar

Pietzsch

Bock

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

108

101

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Amorphous materials represent a large and important emerging area of material's science. Amorphous oxides are key technological oxides in applications such as a gate dielectric in Complementary metal-oxide semiconductor devices and in Silicon-Oxide-NitrideOxide-Silicon and TANOS (TaN-Al 2 O 3 -Si 3 N 4 -SiO 2 -Silicon) flash memories. These technologies are required for the high packing density of today's integrated circuits. Therefore the investigation of defect states in these structures is crucial. In this work we present X-ray synchrotron measurements, with an energy resolution which is about 5-10 times higher than is attainable with standard spectrometers, of amorphous alumina. We demonstrate that our experimental results are in agreement with calculated spectra of amorphous alumina which we have generated by stochastic quenching. This first principles method, which we have recently developed, is found to be superior to molecular dynamics in simulating the rapid gas to solid transition that takes place as this material is deposited for thin film applications. We detect and analyze in detail states in the band gap that originate from oxygen pairs. Similar states were previously found in amorphous alumina by other spectroscopic methods and were assigned to oxygen vacancies claimed to act mutually as electron and hole traps. The oxygen pairs which we probe in this work act as hole traps only and will influence the information retention in electronic devices. In amorphous silica oxygen pairs have already been found, thus they may be a feature which is characteristic also of other amorphous metal oxides.stochastic quench | X-ray absorption spectroscopy | ab initio | coating D espite early attempts to describe the fundamental electronic properties of noncrystalline semiconductors (1-5), experimental and theoretical knowledge of localized states in the gap of amorphous semiconductors and insulators is still limited. General features of the electronic structure of amorphous semiconductors are quite well known, such as the broad distribution of coordinations and the lack of long range order that induces valence and conduction band tails in the band gap (6). However, the origin of these states is less explored experimentally (7,8) and theoretical investigations are mainly limited to the crystalline polymorphs (9-11). Amorphous Alumina (am-Al 2 O 3 ) is currently one of the key technological amorphous materials, where one promising application of am-Al 2 O 3 is as a high-k dielectric in transistors (12). The use of am-Al 2 O 3 in TANOS (TaN-Al 2 O 3 -Si 3 N 4 -SiO 2 -Silicon) flash memories, which are currently investigated for gigabite and terabite scale flash memories, puts even higher demands on alumina as a current-blocking high-k dielectric.From optical absorption and photoluminescence, states related to F-centers (9, 10) and impurities have been identified in the band gap of am-Al 2 O 3 down to 3.18 and 3.25 eV relative to the valence band edge (13,14). In another study, electronbeam induced states in the am-Al ...

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Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

Unveiling the complex electronic structure of amorphous metal oxides

Århammar

Pietzsch

Bock

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

108

101

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“…Also, T-A1203 is characterized by a network of pores having a diameter and a mutual distance of the order of 10 nm (100 A) [Singh et al, 1981], although, as discussed above, such a network of pores may not affect electrical breakdown Pawlowski [1988] found that the breakdown upon the porosity and varied from 9 to 18 erably below the bulk values of 70 kV/mm. Thinner, sputtered A1203 films were measured by Bhatia et al [1989]. For the largest thickness of 0.45 pm, the breakdown strength was 60 kV/mm.…”

Section: Electrical Breakdown Strengthmentioning

confidence: 99%

Cryogenic Properties of Inorganic Insulation Materials for ITER Magnets: A Review

Simon¹

1994

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“…Such optimized AlO x layers are of interest for the purpose described above. 10,11,16,17 We extend these investigations by a study of the influence of these parameters on the electrical properties of AlO x films. IV, the oxygen concentration in the sputter gas ͑Ar͒ and the residual base pressure in the prepa-a͒ Present address: Lehrstuhl für Feststoff-und Grenzflächenverfahrenstechnik, Friedrich-Alexander Universität Erlangen-Nürnberg, Cauerstr.…”

Section: Introductionmentioning

confidence: 93%

Correlation of chemical composition and electrical properties of rf sputtered alumina films

Voigt¹,

Bergmaier²,

Dollinger³

et al. 2009

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Articles you may be interested inStructural and electrical properties of high-κ Bi 2 Mg 2 ∕ 3 Nb 4 ∕ 3 O 7 pyrochlore films on silicon for possible gate dielectric applications Substrate biasing effect on the electrical properties of magnetron-sputtered high-k titanium silicate thin films Influence of deposition pressure and rf power on the structure and electrical properties of Zr 0.8 Sn 0.2 Ti O 4 thin films prepared by rf magnetron sputtering Properties of reactively radio frequency-magnetron sputtered ( Zr , Sn ) TiO 4 dielectric films Alumina films were prepared by radio frequency magnetron sputtering from an aluminum oxide target on an indium tin oxide covered glass. The purpose of the study was to test the influence of the sputter parameters on the elemental composition, surface morphology, and electrical insulation properties ͑breakdown fields and leakage currents͒. Tested parameters were the sputter gas ͑Ar͒ pressure, the sputter rate, the sputter power, the sputter gas composition ͑Ar: O 2 ͒, the conditioning of the target, the residual base pressure, and the substrate temperature. The surface morphology of the films was investigated by atomic force microscopy. Depth profiles of the elemental compositions were measured by elastic recoil detection using energetic heavy ions, and the insulation properties were investigated by current voltage measurements and impedance spectroscopy. The main finding is that the leakage currents increase by about five orders of magnitude, if the atomic ratio of O:Al increases from 1.35 to 2.0. In parallel the breakdown fields decrease by a factor of 100, and the character of the breakdowns changes from soft to hard. The highest breakdown fields ͑2.4 MV/ cm͒ and smallest leakage currents ͑6.5ϫ 10 −8 A / cm 2 at 2.0 MV/ cm͒ are obtained for slightly Al rich films with small atomic concentrations of H ͑Ͻ0.5 at. % ͒. These films were sputtered in pure Ar and under the lowest possible pressure of the residual gas.

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Alumina films by sputter deposition with Ar/O2: Preparation and characterization

Cited by 49 publications

References 0 publications

Unveiling the complex electronic structure of amorphous metal oxides

Unveiling the complex electronic structure of amorphous metal oxides

Cryogenic Properties of Inorganic Insulation Materials for ITER Magnets: A Review

Correlation of chemical composition and electrical properties of rf sputtered alumina films

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