Analysis and Control of Ferroelectric/Semiconductor(Metal)Interface for Their Device-Application

本文研究了铁电薄膜与硅器件相结合的新的存储器件开发中的重要界面现象。采用MOCVD法制备的Pb（Zr，Ti）O_3（PZT）薄膜作为实验材料。主要结论如下：1.在Ir/SiO_2衬底上沉积PZT薄膜时，台阶覆盖率为76-93%，而在600 ℃下沉积PZT薄膜时，Pt/SiO_2台阶发生形变;这种变形主要是由于Pb向台阶中的扩散引起的。2.在SiO_2/SiO_2上的Ir和/或Iro_2导电膜Si在抑制PZT元素向SiO_2中扩散方面起着有效的阻挡作用，用它们组成的底电极制作的SiO_2/Si基PZT电容器具有良好的极化疲劳性能。3.金属/铁电/半导体型场效应晶体管（MFS-场效应晶体管（FET）要成功地用作非伏打存储器，必须克服两个严重的困难：（1）在F/S界面上存在的载流子陷阱的数量必须足够小，以使场效应在S侧很好地工作。（2）MFS-FET的栅极F必须设计成使铁电剩余极化能有效地作用于FET沟道。困难（1）可以通过F膜的高介电常数来克服，而在开始时，关于（2），需要进一步研究以给出F膜或F电容器的电特性的更详细的描述。

This study has been performed on the interfacial phenomena that heve become of considerable importance in the development of new memory devices by technologically combining ferroelectirc films with silicon devices. The Pb (Zr, Ti) O_3 (PZT) films by MOCVD were used as the experimental ferroelectric species. The importan knowledge derived from this study can be briefly summarized as follows.1.Good step coverage (76-93%) was obtained for thin PZT films depostied on Ir/SiO_2, whereas deformation of Pt/SiO_2 steps was observed when PZT films were deposited at 600ﾟC ; this deformation was mainly caused by the diffusion of Pb into the steps.2.This conductive films of Ir and/or Iro_2 on SiO_2/Si playd the role of an effective barrier in suppressing diffusion of the PZT elements into SiO_2 and, with bottom electrodes composed of them good polarization-fatigue properties were confirmed for the PZT capacitors on SiO_2/Si.3.For Metal/Ferroelectric/Semiconductor type field effect transister (MFS-FET) to succeed as a non-voltaic memory, two serious difficulties must be overcome : (1) the amount of carrier traps existing at the F/S intreface must be small enough for the field effect to operata well at the S side.(2)The gate F Of MFS-FET must be designed so that ferroelectric remnant Polarization can operate effectively on the FET channel. The difficulty (1) can be surmounted by high dielectric constant of the F film, while initially, regarding (2), a further investigation will be needed to give more detailed descriptions of the electrical properties of F film or F Capacitor.