Electrical Properties of Srta 2 O 6 Thin Films Deposited by Plasma Enhanced Atomic Layer Deposition (Peald)

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ELECTRICAL PROPERTIES OF SrTa2O6 THIN FILMS DEPOSITED BY PLASMA ENHANCED ATOMIC LAYER DEPOSITION (PEALD)

Won-Jae Lee, Chang-Ho Shin, In-Kyu You, Il-Suk Yang, Sang-Ouk Ryu, Byoung-Gon Yu, and Kyoung-Ik Cho, Soon-Gil Yoon1 and Chun-Su Lee2 Micro-Electronics Technology Laboratory, ETRI, 161 Kajong-dong, Yusong-gu, Daejon 305-600, Korea, 1 Department of Materials Engineering, Chungnam National University, Yusong-gu, Daejon, 305764, Korea 2 Genitech. Co., Ltd., 1694-5, Shinil-dong, Daedug-gu, Daejon, 306-230, Korea ABSTRACT The SrTa2O6 (STO) thin films were prepared by plasma enhanced atomic layer deposition (PEALD) with alternating supply of reactant sources, Sr[Ta(C2H5O)5(C4H10NO)]2 {Strontium bis-[tantalum penta-ethoxide dimethyllaminoethoxide]; Sr(Ta(OEt)5…dmae)2} and O2 plasma. It was observed that the uniform and conformal STO thin films were successfully deposited using PEALD and the film thickness per cycle was saturated at about 0.8 nm at 300oC. Electrical properties of SrTa2O6 (STO) thin films prepared on Pt/SiO2/Si substrates with annealing temperatures have been investigated. While the grain size and dielectric constant of STO films increased with increasing annealing temperature, the leakage current characteristics of STO films slightly deteriorated. The leakage current density of a 40nm-STO film was about 5×10-8A/cm2 at 3V.

INTRODUCTION Thin dielectric layers are of the great importance and range widely in applications such as the dielectrics in semiconductor devices and in electrolytic capacitors, the protective layer in electroluminescent (EL) thin film display [1-4]. Alternate materials with a permittivity higher than that of SiO2 are needed to be able to use thicker gate dielectrics in achieving the required capacitance without tunneling currents, and thereby continue the evolution toward higher integration densities. The replacement of SiO2 with high-permittivity dielectrics is a major challenge in which the basic research and the near-future needs of the semiconductor industry merge [5-7]. The reduction of thin film to nanometer dimension for new technologies requires exquisite control of film thickness, conformallity, crystallinity and morphology. Lower deposition temperature is also required because interlayer diffusion may destroy the properties of nanoscale devices. Many of these requirements can be achieved by growth controlled at single atomic layers by means of binary reaction sequence chemistry [8,9]. In this study, we have prepared SrTa2O6 (STO) thin films using a plasma enhanced atomic layer deposition (PEALD) equipment, and then investigated the electrical properties of Pt/SrTa2O6/Pt structures with various annealing temperatures of STO films. To date, studies on only STO thin films have not been reported, except for a study on electrical properties of MFMIS-FET structure using spin-coated STO films as an insulator [10]. Furthermore, since D13.3.1

ferroelectric Bi-layered structure oxides such as SrBi2Ta2O9 (SBT) thin films are very promising for degradation-free FRAM application on Pt

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