Thin Solid Films 410 (2002) 107–113 0040-6090/02/$ - see front matter  2002 Elsevier Science B.V. All rights reserved. PII: S0040-6090 Ž 02 . 00254-7 Comparative analysis for the crystalline and ferroelectric properties of Pb(Zr,Ti)O thin films deposited on metallic LaNiO and Pt electrodes 3 3 B.G. Chae *, Y.S. Yang , S.H. Lee , M.S. Jang , S.J. Lee , S.H. Kim , W.S. Baek , S.C. Kwon a, a a a b b c c Research Center for Dielectric and Advanced Matter Physics, Pusan National University, san 30 Jangjeon Keumjeong, Pusan 609-735, a South Korea Electronics and Telecommunications Research Institute (ETRI), 161 Kajong-Dong, Yusong, Taejon 305-350, South Korea b Korea Institute of Machinery and Materials (KIMM), Changwon, Kyungnam 641-010, South Korea c Received 26 August 1999; received in revised form 11 June 2001; accepted 18 July 2001 Abstract The crystalline quality and ferroelectricity of the Pb(Zr,Ti)O (PZT) films deposited on the metallic LaNiO (LNO) and Pt 3 3 electrodes were comparatively analyzed to investigate the possibility for their application to non-volatile memory devices. LNO thin films were successfully deposited on various substrates by using r.f. magnetron sputtering even at a low temperature ranging from 250 to 500 8C, and the ferroelectric PZT thin films were spin-coated onto the LNO and Pt bottom electrodes. Metallic LNO thin films exhibited w100x orientation irrespective of the substrate species and PZT films coated onto LNO films had highly a- and c-axis orientations, while those with Pt bottom electrode were polycrystalline. PZT films with LNO bottom electrode had smaller grain size and larger dielectric constant compared to those grown on the Pt electrode. The ferroelectric thin films fabricated on LNO bottom electrode displayed an asymmetric D–E hysteresis loop, which was explained by the defect effects formed at the interface. Especially, the LNOyPZTyLNO capacitor was found to significantly improve the polarization fatigue and the effects of the LNO electrodes to the fatigue were discussed.  2002 Elsevier Science B.V. All rights reserved. Keywords: Crystallisation; Ferroelectric properties; Sputtering; Polarization fatigue 1. Introduction Ferroelectric thin films have received much attention for application in non-volatile random access memory (NVRAM) devices w1–3x. Among these films, the Pb(Zr,Ti)O (PZT) film was known to be a representa- 3 tive for the NVRAM devices because of the ease in fabricating the thin films and their good ferroelectricity w4–6x. However, there have been several problems such as imprint, leakage current, and polarization fatigue in memory devices with these films w7,8x. In recent years, conducting oxide electrodes such as IrO , RuO and YBa Cu O (YBCO) were considered 2 2 2 3 7yx to be promising alternatives for solving the drawbacks in using conventional metal electrodes w9–11x. The ferroelectric films coated on metal oxide films with a perovskite structure like SrRuO and YBCO have good 3 crystallinity and ferroelectric properties due to lattice *Corresponding author. Fax: q82-42-860-5202. E-mail address: bgchae@cadvax.etri.re.kr (B.G. Chae). matching w11x. Recently, a LaNiO (LNO) thin film has 3 been developed as a new metal oxide electrode, which has a pseudocubic structure w12x. Since LNO films were first deposited by pulsed laser deposition (PLD) w13x, they have been successfully fabricated to explore the properties of films by various methods such as r.f. sputtering and the sol–gel method w14–16x. It was reported that the lattice constant of LNO thin films is approximately 3.84 A, similar to that of the perovskite ˚ ferroelectric films and the resistivity of the deposited films is elucidated to 225 mVØcm w17x. Particularly, highly textured PZT films were also obtained on w100x- oriented LNO substrates by the sol–gel technique and showed great improvement in polarization fatigue w15x. It was difficult for LNO bulk ceramic to form a rhombohedral structure w18x. However, the thin film LNO metal oxide is easily grown with a preferential w100x orientation of the pseudocubic structure. Using LNO films as electrodes has two advantages compared with other metal oxide electrodes. First, the LNO films