(100) Oriented Sputter-deposited Pt Thin Films on MgO/Fe Composite Bilayers using SiO 2 /Si substrates With Addition of
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1255-M03-17
(100) oriented sputter-deposited Pt thin films on MgO/Fe composite bilayers using SiO2/Si substrates with addition of O2 during Pt sputtering 1
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Hiroshi Nakano , Wang ChongE , Tatsuro Matsumoto , Yuji Murashima , 2 1 Kazuki Komaki and Shigeki Nakagawa 1 Department of Physical and Electronics, Tokyo Institute of Technology, JAPAN 2 Panasonic Electronic Devices Japan Co., Ltd.
ABSTRACT Highly (100)-oriented Pt films with 100 nm-thick can be grown on MgO(100)/Fe composite bilayers using SiO2/Si substrates by the facing-targets sputtering (FTS) method with Ar/O2 gas mixtures at a substrate temperature above 500 ℃. Since Pt(100) texture usually has higher surface energy than Pt(111) texture, Pt(100) preferential orientation films was observed less than 20 nm by using MgO(100)/Fe buffer layers in Ar gas. Addition of O2 gas during the deposition of Pt layer causes (100) orientation of the Pt thin films even though the thickness of the Pt thicker than 100nm. O2 gas has an insignificant effect resistivity of Pt films. Perovskite of PZT films with (100) preferential orientation can be grown on the Pt(100) layer prepared on the MgO(100)/Fe layers
INTRODUCTION A lot of attention has been paid to dielectric thin films of perovskite type composite oxide materials, because electronic devices require the materials as key materials such as highdielectric-constant materials in dynamic random-access memory (DRAM) cells and ferroelectric random access memory (FeRAM) devices [1]. Therefore, it is necessary to fabricate ferroelectric oxide thin films that have high dielectric constant and low loss tangent [2] such as Pb(Zrx, Ti1−x)O3 (PZT) and Ba1-xSrxTiO3 (BST). In order to apply them to capacitive devices, bottom electrode layers for the oxide films are very important, since they play a role to affect the crystallinity of the oxide films. Platinum (Pt) is one of the popular bottom electrode films for perovskite oxide films. Since dielectric properties of ferroelectric films are originated from the displacement of ions in a crystal along a c-axis direction, c-axis oriented ferroelectric thin films are required to attain better dielectric properties. Since (100) lattice plane of the Pt has an epitaxial relationship to the growth of (100) texture of the perovskite (100) plane, the (100) oriented Pt films are required in order to attain c-axis oriented perovskite type ferroelectric films. However, it is difficult to prepare Pt(100) preferential orientation thin films on commercially used substrate materials, such as thermally oxidized Si wafers. Platinum films tend to have (111) preferential orientation when they are deposited on an amorphous substrate, where no lattice matching is expected [3]. Epitaxially grown Pt(100) films have been prepared on MgO(100) single-crystal substrates at high substrate temperatures and low deposition rates [3-5]. Consequently, epitaxially grown Pt(100) thin films prepared on a MgO(100) buffer layers have a
great deal of potential in industrial applications, for their possibilities o
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