Aqueous solution–gel preparation of ultrathin ZrO2 films for gate dielectric application

Hardy, An; Elshocht, Sven Van; Adelmann, Christoph; Conard, Thierry; Franquet, Alexis; Douhéret, Olivier; Haeldermans, I.; D’Haen, Jan; Gendt, Stefan De; Caymax, Matty; Heyns, Marc; D’Olieslaeger, M.; Bael, Marlies K. Van; Mullens, J.

doi:10.1016/j.tsf.2008.04.017

Cited by 25 publications

(19 citation statements)

References 29 publications

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“…Moreover, in recent years, zirconia-based materials, including ZrO 2 -SiO 2 , have been proposed as a promising high-gate dielectric material for metal-oxide-semiconductor ͑MOS͒ transistors. [1][2][3] Thin films of ZrO 2 can be prepared by a range of methods, including physical vapor deposition, 4 chemical vapor deposition, 5 atomic layer deposition, 6 chemical solution deposition, 3,7 and anodizing. 8,9 Anodizing is the most simple and easiest method to form dielectric oxides, and this has been extensively used to form dielectric oxide films on aluminum and tantalum for electrolytic capacitor applications.…”

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confidence: 99%

Phase Transformation and Capacitance Enhancement of Anodic ZrO[sub 2]–SiO[sub 2]

Koyama¹,

Aoki²,

Sakaguchi

et al. 2010

J. Electrochem. Soc.

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Capacitance enhancement of anodic oxide films on zirconium by adding silicon is reported here with correlation to the phase transformation of the oxide. The anodic oxide film formed on zirconium consists mainly of monoclinic ZrO 2 , which changes to tetragonal ZrO 2 phase on the Zr-5.5 atom % Si. Further increase in the silicon contents to 10 and 16 atom % results in the formation of amorphous oxide up to 30 V, above which two-layered films, comprising an outer crystalline tetragonal-phase oxide layer and an inner amorphous layer, are developed. The relative thickness of the outer crystalline layer to the total film thickness increases with formation voltage. The highest capacitance of the anodic oxide films is obtained on the Zr-10 atom % Si. The changes in capacitance, permittivity and formation ratio of anodic oxide films with alloy composition are discussed with phase transformation and growth process of anodic oxides. © 2010 The Electrochemical Society. ͓DOI: 10.1149/1.3503592͔ All rights reserved.Manuscript submitted August 9, 2010; revised manuscript received September 23, 2010. Published October 22, 2010 ZrO 2 is an important inorganic material for high-temperature applications, due to many useful properties such as high strength and stability at high temperatures, oxide ion conductivity at elevated temperatures and radiation-resistant properties. These features make ZrO 2 attractive for oxygen sensors, solid oxide fuel cells, and nuclear materials. Moreover, in recent years, zirconia-based materials, including ZrO 2 -SiO 2 , have been proposed as a promising high-gate dielectric material for metal-oxide-semiconductor ͑MOS͒ transistors. 8,9 Anodizing is the most simple and easiest method to form dielectric oxides, and this has been extensively used to form dielectric oxide films on aluminum and tantalum for electrolytic capacitor applications. Tantalum electrolytic capacitors are widely used in electronics industry, but due to limitation of natural resources of tantalum and for high demand of increasing capacitance, alternative abundant materials that form oxides with higher permittivity, such as niobium and titanium, have been studied. [10][11][12][13][14][15][16] Zirconium forms usually crystalline anodic oxide films, in contrast to the formation of amorphous anodic oxides on a range of valve metals, including aluminum, bismuth, niobium, tantalum and tungsten. 17 The crystalline structure of anodic zirconium oxide films is influenced by surface treatments prior to anodizing and electrolyte for anodizing. When magnetron-sputtered zirconium is anodized in ammonium pentaborate electrolyte without pretreatment of the deposited surface, crystalline oxide films, consisting mainly of monoclinic ZrO 2 , are developed. 9 The monoclinic phase of ZrO 2 is thermodynamically the most stable at ambient temperature, but amorphous and high-temperature stable phases of cubic or tetragonal ZrO 2 are also often found in the anodic oxide films formed on chemically polished zirconium, particularly at low formation voltage...

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confidence: 99%

Phase Transformation and Capacitance Enhancement of Anodic ZrO[sub 2]–SiO[sub 2]

Koyama¹,

Aoki²,

Sakaguchi

et al. 2010

J. Electrochem. Soc.

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“…Polymorphic ZrO 2 possesses three different crystal structures at atmospheric pressure: monoclinic, tetragonal (t-), and cubic (c-), which are stable in the bulk form below *1170°C, between 1170 and 2370°C, and above *2370°C, respectively [6], and the mechanical, electrical, and catalytic properties are dependent on the crystal structures [7,8]. Particularly, stabilization of the high-temperature t-and c-phases at room temperature has been of significant interest for engineering applications and has generally been achieved by modulating the film thickness or particle/crystallite size [9,10] or by substituting Zr 4? with divalent or trivalent elements, such as Mg 2?…”

Section: Introductionmentioning

confidence: 99%

Phase and structural evolution of sol–gel synthesized ZrO2/Si thin films under heat treatment

et al. 2012

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ZrO 2 /Si thin films were fabricated using a solgel technique, and the chemical state change and structural evolution from sol to gel to Zr oxide by heat treatment were investigated. The precursor sol was synthesized using a Zr-acetylacetonate (Zr-acac) precursor, spin-coated, dried on Si(100) substrates, and then annealed at 300-700°C in air. With increased annealing temperature of the sol-gelderived layer, Zr-acac decomposed into Zr-acetate, an amorphous ZrO 2 phase formed, and crystallization into a tetragonal phase occurred. In addition, the ZrO 2 layer became denser and the interfacial layer between ZrO 2 and Si thickened, whereas the surface morphology was nearly unaffected and remained smooth with root-mean-square values \ 4.5 Å .

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“…Previously, the advantages of using aqueous chemical solution deposition for the fabrication and screening of ultrathin dielectric oxide films have been reported 16,17 . It was shown that the k values obtained from CSD films were equal to those for other deposition techniques, such as atomic layer deposition, which supports the use of this deposition technique for high k films.…”

Section: Introductionmentioning

confidence: 99%

Crystallization resistance of barium titanate zirconate ultrathin films from aqueous CSD: a study of cause and effect

et al. 2009

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Aqueous solution–gel preparation of ultrathin ZrO2 films for gate dielectric application

Cited by 25 publications

References 29 publications

Phase Transformation and Capacitance Enhancement of Anodic ZrO[sub 2]–SiO[sub 2]

Phase Transformation and Capacitance Enhancement of Anodic ZrO[sub 2]–SiO[sub 2]

Phase and structural evolution of sol–gel synthesized ZrO2/Si thin films under heat treatment

Crystallization resistance of barium titanate zirconate ultrathin films from aqueous CSD: a study of cause and effect

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