ZrO2 基外延铁电薄膜制备及性能研究

  量子通信､云计算､物联网､人工智能等高新技术的发展对存储芯片､逻辑器件提出了更高的要求。集成电路发展到纳米时代,传统材料和平面式结构已陷入发展瓶颈,小尺寸带来的漏电及隧穿效应严重阻碍摩尔定律发展及器件的微型化。在高介电常数 HfO₂､ZrO₂ 基材料中意外发现的铁电和反铁电性为后摩尔时代晶体管制备以及新型存储器的发展带来了一个全新的解决方案。以往研究和制备的铪锆基铁电薄膜为多晶多相的,与此相比外延薄膜有更少的缺陷和更可控微的观结构,更容易揭示铁电机理及调控铁电性能。

  本文主要基于激光脉冲沉积技术,制备高质量外延铁电 ZrO₂薄膜,探寻 ZrO₂薄 膜生长过程中温度､氧压､厚度等因素对薄膜相结构及铁电性能的影响,研究 ZrO₂ 外延膜中 Hf 掺杂对铁电相的影响,探究 ZrO₂与衬底之间的外延关系。实验结果表明,生长条件为 800 ℃､10 Pa 和 10 nm 时,所制备的 ZrO₂铁电薄膜具有良好的微观和宏观铁电性能,剩余极化值可达 55 μC/cm²。在探索不同 Hf 含量掺杂和衬底取向对铪锆氧薄膜相结构和性能的影响中发现纯的 ZrO₂ 体系是铁电态,而不是以往报道的反铁电态,且相比于其他含量的铪锆氧薄膜,ZrO₂ 薄膜中有最大的铁电剩余极化值。此外研究发现不同的面内原子排列关系对铁电相含量和性能有显著影响,铁电相 ZrO₂ 与底部 LSMO 具有以下外延关系:ZrO2[02 - 2]//LSMO[001]。这种特殊的外延关系致使 STO（110）衬底上外延的 ZrO₂ 有最高的铁电相比例以及最佳的铁电性。

  本文通过对铁电 ZrO₂ 薄膜生长条件和结构性质的探究得出了最佳生长条件, 并且深入研究了铁电相结构特性及衬底取向对氧化锆薄膜相组成的影响,为该材料在电子器件领域的应用奠定了基础。 

  The development of new high-tech industries such as quantum communication, cloud computing, the Internet of Things, and artificial intelligence have created higher demands for storage chips and logic devices. In nano-age integrated circuits, the development of traditional materials and planar structures are hindered. The leakage and tunneling effects caused by small size seriously hinder the development of Moore's Law and the miniaturization of devices.The unexpected ferroelectric and antiferroelectric properties discovered in high dielectric constant HfO₂ and ZrO₂ materials have brought a new solution to post-Moore's Law transistor development and new type storage. The hafnium zirconium based ferroelectric films studied in the past are usually polycrystalline and polyphase. Compared with polycrystalline films, the epaxial films have fewer defects and more controllable microstructure, and it is easier to reveal the ferroelectric mechanism and the control of ferroelectric properties.

  In this paper, laser pulse deposition technology is used to prepare high-quality epitaxial ferroelectric ZrO₂ film, explore the influence of temperature, oxygen pressure, thickness and other factors on the film phase structure and ferroelectric properties during the growth process of ZrO₂ film, study the influence of Hf doping amount on the ferroelectric phase, explore the epitaxial relationship of ZrO₂.Experimental results show that under growth conditions of 800 ℃, 10 Pa, and 10 nm, the prepared ZrO₂ ferroelectric film has good microscopic and macroscopic ferroelectric properties, with a remanent polarization value of up to 55 μC/cm² . The prepared ZrO₂ film is in a ferroelectric state, rather than the antiferroelectric state reported in the past. Compared with the films with different Hf doping amounts, the pure ZrO₂ film has the largest ferroelectric remanent polarization value. In addition, it is found that different in-plane atomic arrangement relationships have significant effects on ferroelectric phase content and properties. It is found that ferroelectric phase ZrO₂ has the following epitaxial relationship with bottom LSMO:ZrO2[02-2]//LSMO[001].This special epitaxial relationship results in the highest ferroelectric phase content and the best ferroelectric properties of ZrO₂ epitaxial on STO（110） substrates.

  In this paper, the optimum growth conditions of ferroelectric ZrO₂ thin film were obtained, the ferroelectric phase structure was investigated, and the influence of substrate orientation on the phase composition of zirconia thin film was studied, which laid the foundation for the application of this material in the field of electronic devices.

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