Reactively sputtered tantalum pentoxide thin films for integrated capacitors

Tommi Riekkinen (Corresponding Author), Jyrki Molarius

Research output: Contribution to journalArticleScientificpeer-review

13 Citations (Scopus)

Abstract

The aim of this work was to develop a deposition process for a high-dielectric constant tantalum pentoxide for integrated capacitors. Thin films were deposited reactively on glass wafers using a radio-frequency magnetron sputtering cluster tool at various O2/Ar flow ratios. By using 2 MeV 4He+ backscattering spectroscopy and X-ray diffraction, the films obtained showed a stoichiometric orthorhombic β-Ta2O5 phase at 20% O2 in the sputtering gas flow. With low-frequency measurements (f=100 kHz), a 200×200-μm2 square metal–insulator–metal (MIM) capacitor with copper electrodes and a 340-nm thick dielectric gave a capacitance density of 0.066 μF/cm2, with a quality factor (Q) of 650. The value of the relative permittivity (εr) was approximately 25 determined from MIM capacitors of various sizes. The surface roughness of the 376-nm thick oxide film was found to be small: 0.255 nm. The largest measured capacitor (200×200 μm2) gave reasonable results at low frequencies. When the frequency was increased (100 kHz–20 GHz) only for the smaller capacitors (30×30 μm2) the capacitance remained constant. However, the Q values decreased of the smaller capacitors as a function of frequency. Processed tantalum pentoxide MIM capacitors possessed reasonable electrical properties below 2 GHz and good potential for further improvement.
Original languageEnglish
Pages (from-to)392-397
JournalMicroelectronic Engineering
Volume70
Issue number2-4
DOIs
Publication statusPublished - 2003
MoE publication typeA1 Journal article-refereed
EventMaterials for Advanced Metallization 2003 - La Londe Les Maures, France
Duration: 9 Mar 200312 Mar 2003

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Keywords

  • reactive sputtering
  • thin film capacitor
  • thin films
  • tantalum pentoxide
  • tantalum

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