Environmentally stable flexible metal-insulator-metal capacitors using zirconium-silicate and hafnium-silicate thin film composite materials as gate dielectrics

Jagan Singh Meena, Min Ching Chu, Chung Shu Wu, Srikanth Ravipati, Fu-Hsiang Ko*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Fully flexible metal-insulator-metal (MIM) capacitors fabricated on 25 μm thin polyimide (PI) substrates via the surface sol-gel process using 10-nm-thick zirconium-silicate (ZrSi xO y) and hafnium-silicate (HfSi mO n) films as gate dielectrics. The surface morphology of the ZrSi xO y and HfSi mO n films were investigated using atomic force microscopy and scanning electron microscopy, which confirmed that continuous and crack-free surface growth had occurred on the PI. Both the films treated with oxygen (O 2) plasma and annealing (ca. 250 12°C) consisted of amorphous phase; confirmed by X-ray diffraction. We employed X-ray photoelectron spectroscopy (XPS) at high resolution to examine the chemical composition of the films subjected to various treatment conditions. The shift of the XPS peaks towards higher binding energy revealed the O 2 plasma-pretreatment followed by annealing was the most effective process to the surface oxidation at relatively low-temperature, for further passivate the grease traps and making dielectric films thermally stable. The ZrSi xO y and HfSi mO n films in sandwich-like MIM configuration on the PI substrates exhibited the low leakage current densities of 7.1 × 10 -9 and 8.4 × 10 -9 A/cm 2 at applied electric field of 10 MV/cm and maximum capacitance densities of 7.5 and 5.3 fF/μm 2 at 1 MHz, respectively. In addition, the ZrSi xO y and HfSi mO n films in MIM capacitors showed the estimated dielectric constants of 8.2 and 6.0, respectively. Prior to use of flexible MIM capacitors in advanced flexible electronic devices; the reliability test was studied by applying day-dependent leakage current density measurements up to 30 days. These films of silicate-surfactant mesostructured materials have special interest to be used as gate dielectrics in future for flexible metal-oxide-semiconductor devices.

Original languageEnglish
Pages (from-to)6858-6867
Number of pages10
JournalJournal of Nanoscience and Nanotechnology
Volume11
Issue number8
DOIs
StatePublished - 1 Aug 2011

Keywords

  • Flexible substrate
  • Hafnium-silicate
  • MIM capacitor
  • Sol-gel spins coating
  • Zirconium-silicate

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