Investigation and Control of Ferroelectric / Conductor Interface Phenomena and Their Applications to Memory Devices

铁电/导体界面现象的研究和控制及其在存储器件中的应用

• 批准号: 07650374
• 负责人: SHIMIZU Masaru
• 金额: $ 1.6万
• 依托单位: Himeji Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07650374/
• 关键词: IrO_2 ceramics target; MOCVD method; Pb (Zr, Ti) O_3 thin films; barrier; SIMS; DLTS; C-V mesurment; interface state; Ir電極; RFスパッタ法; Pb (Zr, Ti) O_3薄膜; 全反射X線回折法; MOCVD; PZT薄膜; メモリ素子; 強誘電体; Ir; IrO_2; 分極反転特性; 界面

The growth conditions for Pt, Ir and IrO_2 electrodes in PZT capacitors by sputtering and for PZT by MOCVD were optimized. Oriented IrO_2 films were successfuly obtained by RF sputtering using a ceramic IrO_2 target for the first time. Ferroelectric PZT thin films were also grown successfully on these electrodes.The mutual diffusion between PZT thin film and electrode materials was investigated by SIMS (Secondary Ion Mass Spectroscopy) measurements. Their measurments indicated that Ir and Ir/IrO_2 provided a much better barrier for Pb, Zr and Ti than Pt. PZT capacitors with Ir, IrO_2 and Ir/IrO_2 bottom electrodes showed a lower dielectric constant and remanent polarization, and a larger coercive field than those of PZT capacitors using both top and bottom Pt electrodes due to their poor crystalline quality. PZT capacitors with both Ir and IrO_2 top and bottom electrodes (Ir/IrO_2/PZT/Ir/IrO_2/SiO_2/Si) showed no fatigue up to a switching cycle of 10^<11>.Using the energy dispersive type total reflection X-ray diffraction method, crystalline structure and distortion of the PbTio_3 and PZT films grown on Pt/MgO were investigated.The interface between the layrs in ferroelectric/conductor/semiconductor structure was evaluated by the C-V measurement and the DLTS (Deep Level Transient Spectroscopy) method. From these measurements it was found that there exsisted some interface states at the PZT/Si interface. More details regarding the effects of photoexcitation on the interface sstate are now under investigation.

对溅射PZT电容器中的Pt、Ir和IrO_2电极以及MOCVD PZT电极的生长条件进行了优化。首次利用陶瓷IrO_2靶材通过射频溅射成功获得了取向IrO_2薄膜。在这些电极上也成功生长了铁电PZT薄膜。通过SIMS（二次离子质谱）测量研究了PZT薄膜和电极材料之间的相互扩散。他们的测量表明，Ir 和 Ir/IrO_2 为 Pb、Zr 和 Ti 提供了比 Pt 更好的势垒。由于结晶质量较差，具有 Ir、IrO_2 和 Ir/IrO_2 底部电极的 PZT 电容器比同时使用顶部和底部 Pt 电极的 PZT 电容器表现出较低的介电常数和剩余极化，以及较大的矫顽场。具有Ir和IrO_2上下电极的PZT电容器(Ir/IrO_2/PZT/Ir/IrO_2/SiO_2/Si)在10^<11>的开关周期内没有表现出疲劳。利用能量色散型全反射X射线衍射方法，对Pt/MgO上生长的PbTio_3和PZT薄膜的晶体结构和畸变进行了研究。 通过C-V测量和DLTS（深能级瞬态光谱）方法评估了铁电/导体/半导体结构中各层之间的界面。从这些测量中发现，PZT/Si 界面处存在一些界面态。有关光激发对界面状态影响的更多细节目前正在研究中。

项目成果

H.Fujisawa: "Dependence of Crystalline Structure and Lattice Parameters on Film Thickness in PbTiO_3/Pt/MgO Epitaxial Structure." Jpn. J.Appl. Phys.35. 4913-4918 (1996)

H.Fujisawa：“PbTiO_3/Pt/MgO 外延结构中晶体结构和晶格参数对薄膜厚度的依赖性”。

Akira Matsumura: "Thermal Effects in Properties of Photovoltaic Currents of Pb(Zn,Ti)O_2 Thin Films" Jpn.J.Appl.Phys.34. 5258-5262 (1995)

Akira Matsumura：“Pb(Zn,Ti)O_2 薄膜光伏电流特性的热效应”Jpn.J.Appl.Phys.34。

M. Shimizu: "Step Goverage of Pb (Zr, Ti) O_3 Thin Films Grown by MOCVD." Mat. Rec. Soc. Symp. Proc.433. 201-206 (1996)

M. Shimizu：“MOCVD 生长的 Pb (Zr, Ti) O_3 薄膜的步进治理”。

M. Shimizu: "Electrical Properties of Pb (Zr, Ti) O_3 Thin Films on Ir and IrO_2 Electrodes by MOCVD" Proc. sthe Tenth Int. Symp. on the Applications of Ferroelectrics. (印刷中).

M. Shimizu：“通过 MOCVD 在 Ir 和 IrO_2 电极上制备 Pb (Zr, Ti) O_3 薄膜的电学特性”，铁电体应用第十期论文。

垂井康夫: "強誘電体薄膜メモリ" サイエンス フォーラム, 377 (1995)

Yasuo Tarui：“铁电薄膜存储器”科学论坛，377（1995）