Formation of Monoclinic Hafnium Titanate Thin Films Via the Sol–Gel Method

Authors

  • Tongjit Kidchob,

    1. Laboratorio di Scienza dei Materiali e Nanotecnologie, Dipartimento di Architettura e Pianificazione, Università di Sassari, Nanoworld Institute and CR-INSTM, Palazzo Pou Salid, Piazza Duomo 6, 07041 Alghero (SS), Italy
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  • Paolo Falcaro,

    1. Associazione CIVEN—Nano Fabrication Facility, Via delle Industrie 5, 30175 Marghera, Venice, Italy
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  • Piero Schiavuta,

    1. Associazione CIVEN—Nano Fabrication Facility, Via delle Industrie 5, 30175 Marghera, Venice, Italy
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  • Stefano Enzo,

    1. Dipartimento di Chimica, Università di Sassari, Via Vienna 2, 07100 Sassari, Italy
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  • Plinio Innocenzi

    Corresponding author
    1. Laboratorio di Scienza dei Materiali e Nanotecnologie, Dipartimento di Architettura e Pianificazione, Università di Sassari, Nanoworld Institute and CR-INSTM, Palazzo Pou Salid, Piazza Duomo 6, 07041 Alghero (SS), Italy
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  • B. Dunn—contributing editor

  • This work was supported by the Italian Ministero dell'Università e della Ricerca (MiUR) through FIRB2001 (RBNE01P4JF) and FIRB2003 (RBNE033KMA) grants.

†Author to whom correspondence should be addressed. e-mail: plinio@uniss.it

Abstract

Hafnium titanate films are generating increasing interest because of their potential application as high-k dielectrics materials for the semiconductor industry. We have investigated sol–gel processing as an alternative route to obtain hafnium titanate thin films. Hafnia-titania films of different compositions have been synthesized using HfCl4 and TiCl4 as precursors. The HfO2–TiO2 system composition with 50 mol% of TiO2 and 50 mol% of HfO2 has allowed the formation of a hafnium titanate film after annealing at 1000°C. The films exhibited a homogeneous nanocrystalline structure and a monoclinic hafnium titanate phase that has never been obtained before in thin films. The films resulted in the formation of homogeneously distributed nanocrystals with an average size of 50 nm. Different compositions, with higher or lower hafnia contents, produced anatase crystalline films after annealing at 1000°C.

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