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

通过将铁电薄膜与硅器件技术相结合，对界面现象进行了研究，这些界面现象对开发新的存储器件具有重要意义。以MOCVD法制备的PZT(PZT)薄膜为铁电材料。主要结论如下：1.在Ir/SiO_2衬底上沉积的PZT薄膜具有良好的台阶覆盖率(76-93%)，而在600ﾟC下沉积的PZT薄膜有明显的台阶形变；这种在SiO_2/Si上的Ir和/或IrO_2导电膜起到了有效阻挡PZT元素向SiO_2中扩散的作用，并且由它们组成的底电极证实了SiO_2/SiO_2上的PZT电容器具有良好的极化疲劳性能。3.为了使金属/铁电/半导体场效应晶体管(MFS-FET)成功地成为非伏安存储器，必须克服两个严重的困难：(1)F/S界面的载流子陷阱数量必须足够小，以便场效应在S一侧很好地工作。(2)MFS-FET的F栅必须设计成能够在FET沟道上有效工作的铁电剩余极化。(1)的困难可以通过F膜的高介电常数来克服，而对于(2)，最初还需要进一步的研究，以给出更详细的F膜或F电容器的电特性的描述。

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.