Grain size dependence of dielectric relaxation in cerium oxide as high-k layer

Chun Zhao,Ce Zhou Zhao,Peter King,Steve Taylor,Paul Chalker,Matthew Werner

doi:10.1186/1556-276x-8-172

Abstract

Cerium oxide (CeO2) thin films used liquid injection atomic layer deposition (ALD) for deposition and ALD procedures were run at substrate temperatures of 150°C, 200°C, 250°C, 300°C, and 350°C, respectively. CeO2 were grown on n-Si(100) wafers. Variations in the grain sizes of the samples are governed by the deposition temperature and have been estimated using Scherrer analysis of the X-ray diffraction patterns. The changing grain size correlates with the changes seen in the Raman spectrum. Strong frequency dispersion is found in the capacitance-voltage measurement. Normalized dielectric constant measurement is quantitatively utilized to characterize the dielectric constant variation. The relationship extracted between grain size and dielectric relaxation for CeO2 suggests that tuning properties for improved frequency dispersion can be achieved by controlling the grain size, hence the strain at the nanoscale dimensions.

Highlights

Cerium oxide (CeO2) is proposed as a possible gate dielectric material in metal-oxide-semiconductor and memory devices for generation devices [1,2]
The atomic layer deposition (ALD) CeO2 samples were grown as crystalline thin films for a range of substrate temperatures within the ALD growth window of the Ce[mmp]4 precursor, with water as an oxidant
X-ray diffraction (XRD) and Raman spectra show an increase in grain size for increasing growth temperatures

Summary

Introduction

Cerium oxide (CeO2) is proposed as a possible gate dielectric material in metal-oxide-semiconductor and memory devices for generation devices [1,2]. This is because CeO2 can be epitaxially grown on a Si (111) surface [3] and because its high ability for oxygen storage makes CeO2 one of the most important automobile exhaust catalysts [4]. In terms of microelectronic applications, atomic layer deposition (ALD) is the most attractive technique for the deposition of CeO2 This is due to its ability to deposit large areas of high-uniformity thin films, good doping control, and superior conformal step coverage on highly non-planar substrates [9]. In ALD, metal alkoxides have the major advantage of high reactivity with H2O,

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