The influence of thin film fabrication process on ferroelectric properties and ferroelectric random access memories

薄膜制造工艺对铁电特性和铁电随机存取存储器的影响

• 批准号: 10450120
• 负责人: SHIOSAKI Tadashi
• 金额: $ 4.42万
• 依托单位: Nara Institute of Science and Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10450120/
• 关键词: Ferroelectric Thin Film; FRAM; MOCVD; Chemical Solution Deposition; Electron-Beam-Induced Reaction; Thermally Stimulated Current; Polarization Fatigue; Imprint; 強誘電体不揮発性メモリー; Pb(Zr,Ti)O_3; 分極反転疲労; 空間電荷; マイクロクラック

Ferroelectric thin films have been interesting materials because of FeRAM application. Therefore, ferroelectric thin films are fabricated by various preparation methods. However, the ferroelectric thin films obtained shows the peculiar properties such as the polarization fatigue, imprint and so on. We studied these phenomena, and obtained the knowledge about them.The thermally stimulated current (TSC) of the this films were examined. The peak of TSC of fatigued sample are obtained, revealing that the main origin of the polarization fatigue phenomena was the domain pinning caused by trapped charge carriers injected by polarization reversal. The internal bias field in the films were also investigated by pulse measurement. The PZT thin films obtained by a chemical solution deposition process exhibited a conspicuous initial voltage shift in the D-E hysteresis loop toward the negative-bias field. It was concluded that the origin of the voltage shift was an internal bias field due to asymmetric space-charge distribution induced by the natural alignment of spontaneous polarization during the cooling process. The internal bias field caused asymmetric depolarization at the zero-bias field.

由于 FeRAM 的应用，铁电薄膜已成为有趣的材料。因此，铁电薄膜可以通过各种制备方法来制备。然而，所获得的铁电薄膜表现出极化疲劳、印记等奇特性能。我们研究了这些现象，并获得了有关它们的知识。检测了该薄膜的热刺激电流（TSC）。获得了疲劳样品的TSC峰值，揭示了极化疲劳现象的主要原因是极化反转注入的俘获载流子引起的磁畴钉扎。还通过脉冲测量研究了薄膜中的内部偏置场。通过化学溶液沉积工艺获得的 PZT 薄膜在 D-E 磁滞回线中表现出明显的初始电压向负偏压场偏移。结论是，电压漂移的根源是由于冷却过程中自发极化的自然排列引起的不对称空间电荷分布而产生的内部偏置场。内部偏置场导致零偏置场处的不对称去极化。