Search for content and authors

Imprint properties of IrO2/Sr2(Ta1-x,Nbx)2O7/SiO2/Si structure device formed by rf sputtering and oxygen radical treatment

Ichirou Takahashi ,  Shigetoshi Sugawa ,  Tadahiro Ohmi 

Tohoku University, Sendai, Japan


Recently, nonvolatile memory devices having a ferroelectric gate structure have considerable attention from the view points of nonvolatile, high-speed, high-density, and obeying the scaling rule. Sr2(Ta1-x,Nbx)2O7 (STN, x=0.3) is suitable for use as a ferroelectric material for ferroelectric memory field-effect transistors, because it has a low dielectric constant. However, the fabrication of STN on an amorphous insulator, such as SiO2, is difficult. In particular, in the case of STN, because its crystallization annealing temperature is 950℃, the metal element of STN and Si react mutually during crystallization annealing. We have already developed and reported [1] the STN formation technology on amorphous SiO2 and MFIS structure device operation. These were realized using (1) a thin seed layer formed by rf sputtering and microwave-excited plasma treatment, and (2) by the formation of a ferroelectric film, whose oxygen vacancy is reduced by ferroelectric multilayer stack (FMLS) deposition. This plasma treatment can oxidize the surface of the film and supply ion bombardment energy to the surface of the film. In this work, we report imprint and data-programing properties of the MFIS structure device. Threshold voltage shipt of the device is within 10mV and 30 mV after writing operation of 109 and 1010 cycles, respectively.

[1] I. Takahashi et. al., Japanese Journal of Applied Physics, Vol. 45, pp. 3207-3212, 2006


Legal notice
  • Legal notice:

Presentation: Poster at E-MRS Fall Meeting 2007, Acta Materialia Gold Medal Workshop, by Ichirou Takahashi
See On-line Journal of E-MRS Fall Meeting 2007

Submitted: 2007-05-22 05:58
Revised:   2009-06-07 00:44