新型不挥发非破坏性读出铁电存储器(MFS)

长期以来，人们认为铁电场效应管是单晶体管、不挥发、非破坏性读出存储器的基本结构。铁电场效应管的基本结构为金属／铁电／半导体（MFS）结构。MFS存储器与其它不挥发性存储器相比在数据传输速率、疲劳特性和工作电压等方面有更大的优点。本论文简单地论述了MFS存储器的结构、工作原理和制备方法。     

铁电存储器中Pb(Zr,Ti)O_3集成铁电电容的制备

在铁电不挥发存储器 (FERAM)技术中 ,集成铁电电容的制备是关键工艺之一。文中提出一种制备集成铁电电容的改进工艺 :采用 lift-off技术在衬底样品表面淀积铁电电容 Pt/Ti下电极 ,然后用 Sol-Gel方法制备 PZT薄膜。在 PZT薄膜未析晶前 ,先将它加工成电容图形 ,再高温退火成为 PZT铁电薄膜。最后完成铁电电容 Pt上电极。与传统工艺相比 ,改进后的工艺能保持 PZT铁电薄膜与金属上电极之间良好的接触界面。测试结果表明 ,工艺条件的变动不会影响 PZT铁电薄膜的成膜和结构 ,从而可得到性能优良的铁电电容。     

应用于非破坏性读出铁电存储器的MFIS FET制备及其特性

将ZrO2和PZT的sol-gel薄膜制备技术应用到非破坏性读出铁电存储器中,制作出应用Al/PZT/ZrO2/p-Si结构的MFIS电容和单管MFIS FET,研究了MFIS电容的界面和存储窗口特性,结果表明ZrO2介质阻挡层和Si衬底以及PZT的附着良好,在±5V测试电压、1MHz测试频率下,存储窗口电压为2.6V左右,与相应的铁电薄膜的正、负矫顽电压差值的比为0.8.对于宽长比为500μm/50μm器件,采用栅极与源极、漏极写入方式,±10V时在写入电压下得到理想的输入-输出特性;小尺寸的40μm/8μm器件在±5V写入电压下特性较好.     

应用于非破坏性读出铁电存储器的MFIS FET制备及其特性

将ZrO2和PZT的sol-gel薄膜制备技术应用到非破坏性读出铁电存储器中,制作出应用Al/PZT/ZrO2/p-Si结构的MFIS电容和单管MFIS FET,研究了MFIS电容的界面和存储窗口特性,结果表明ZrO2介质阻挡层和Si衬底以及PZT的附着良好,在±5V测试电压、1MHz测试频率下,存储窗口电压为2.6V左右,与相应的铁电薄膜的正、负矫顽电压差值的比为0.8.对于宽长比为500μm/50μm器件,采用栅极与源极、漏极写入方式,±10V时在写入电压下得到理想的输入-输出特性;小尺寸的40μm/8μm器件在±5V写入电压下特性较好.     

铁电存储单元的设计和测试

基于被应用于实际设计之中的统一的铁电器件模型，详细讨论了２Ｔ ２Ｃ组态的铁电破坏性读出存储器单元的设计。在此基础上，设计和制造了分立元件的单元测试电路。通过与普通电容的对比实验，证实了铁电破坏性读出随机读取存储器与普通随机读取存储器不同的工作原理和模式。进而获得了被测ＦＲＡＭ单元的特性波形和铁电材料存储特性的有关数据。这些工作为进一步进行大规模铁电存储器的研究作了准备。     

应用于FRAM的集成铁电电容的研究

集成铁电电容的制备是铁电存储器的关键工艺之一。该文采用射频(RF)磁控溅射法在Pt/Ti/SiO2/Si制备Pb(Zr,Ti)O3(PZT)薄膜,上下电极Pt采用剥离技术工艺制备,刻蚀PZT薄膜,形成Pt/PZT/Pt/Ti/SiO2/Si集成电容结构,最后高温快速退火。结果表明,这种工艺条件可制备性能良好的铁电电容,符合铁电存储器对铁电电容的要求。     

铁电存储器在FPGA中应用的初步研究

提出了一种全新的基于铁电存储器FeRAM编程的非挥发FPGA思想(概念)，它主要是针对基于SRAM的FPGA的掉电挥发性问题提出的。文章在采用传统2T—2C结构的铁电存储单元的基础上完成数据的编程操作，并进一步对上述单元进行了电路和时序上的调整设计，提出了在FPGA工作环境下虽破坏性读出但无需回写的铁电存储单元。通过对文中提及的两种单元电路的仿真模拟，实现了编程数据的摔电保护、上电恢复的非挥发功能，初步验证了基于FeRAM编程的非挥发FPGA思想的正确性和可行性。     

MFS结构钛酸铋铁电薄膜掺铌改性研究

基于MFS结构铁电存储器的需要,采用溶胶-凝胶工艺,在p-Si衬底上制备了对Bi4Ti3O12进行B位Ti元素铌元素取代的铁电薄膜,并电镀上银电极构成MFS结构.研究了掺杂浓度对薄膜的微观结构及铁电性能的影响.研究表明,650℃进行退火的BTN薄膜生长形态良好;2％掺杂取代的薄膜铁电性能最佳,剩余极化强度Pr可达到19...     

铁电薄膜的特性、制备及应用

铁电薄膜材料具有自发极化，且其方向随外电场反转．它还具有压电效应、热释电效应等，因此在不挥发存贮器、压力传感器、红外传感器等方面有广泛的应用。铁电薄膜制备工艺与标准ＣＭＯＳ工艺、双极型集成电路工艺以及ＧａＡｓ集成电路工艺相容，使集成铁电技术取得长足的发展。一门崭新的集半导体、电介质等学科于一体的集成铁电学正在崛起。     

不同介电层对HfxZr1-xO2薄膜铁电性能影响的研究进展

近年来,铁电Hf_xZr_1-xO₂(HZO)薄膜受到越来越多的关注,但是铁电层与电极材料层以及铁电层与半导体衬底层之间的界面问题并没有得到解决,阻碍了HZO薄膜的进一步应用。总结了通过引入不同介电层材料,如Al₂O₃、ZrO₂、HfO₂、Ta₂O₅等,调节HZO薄膜铁电性能的方法及其机理;详细介绍了各种介电层材料作为封盖层对HZO薄膜铁电性能的影响,如对HZO薄膜提供平面内应力、控制铁电层的晶粒尺寸及作为铁电层形核核心的作用;最后,总结并展望了利用介电层调控HZO薄膜铁电性能的一般规律,为后续相关研究的开展提供了指导。     

铁电存储器和IC卡

铁电薄膜与半导体集成产生了新一代非易失存储器，与传统的半导体非易失存储器比较具有突出的优点，是新一代ＩＣ卡的理想存储芯片。     

铁电场效应晶体管

介绍了铁电场效应晶体管 (FFET)的基本结构、存储机制、制作方法 ,综述其结构设计的改进、铁电薄膜在 FFET中应用的进展情况 ,探讨围绕铁电薄膜材料、过渡层、结构设计、不同成膜方法及工艺对 FFET存储特性的影响 ,对 FFET的研究现状和存在的一些问题进行评述     

Transfer characteristics in a GaN MFSFET: comparison with a conventional GaN MOSFET

Based on the Miller model, we develop an analytical model for the GaN-based metal–ferroelectric–semiconductor field-effect transistors (MFSFETs). In this article, we investigate the effects of ferroelectric film on the maximum drain current, transconductance and memory window of GaN MFSFET at the different hierarchical thickness values of 10, 30, 50, 100, 200 and 300?nm, as well as the polarisation influence. The results indicate that the thickness of ferroelectric film is one of the critical parameters, and certain trade-off should be made for various potential applications. Moreover, the advantages of GaN MFSFET are also investigated in detail, compared with the conventional GaN metal–oxide–semiconductor field-effect transistor under the conditions of similar design. Our results of simulation shows that GaN MFSFETs hold the numerous advantages in electrical characteristics, such as the maximal drain current reaching 69?mA, and the threshold voltage and the subthreshold slope as low as 1.5?V and 58?mV/decade, respectively. In general, these theoretical predictions not only indicate that GaN MFSFET devices have wide applicational perspectives, but also they provide some important references to the empirical research and the design of new electron devices in the future.     

Highly Enhanced Polarization Switching Speed in HfO2-based Ferroelectric Thin Films via a Composition Gradient Strategy

The next-generation semiconductor memories are essentially required for the advancements in modern electronic devices. Ferroelectric memories by HfO₂-based ferroelectric thin films (FE-HfO₂) have opened promising directions in recent years. Nevertheless, improving the polarization switching speed of FE-HfO₂ remains a critical task. In this study, it is demonstrated that the composition-graded Hf_1-xZr_xO₂ (HZO) ferroelectric thin film has more than two times faster polarization switching speed than the conventional composition-uniform one. Meanwhile, it has excellent ferroelectricity and improved endurance characteristics. It is also discovered that when the HZO thin film has a gradient composition, the polarization-switching dynamics shifts from the nucleation-limited-switching mechanism to the domain-wall growth mechanism. Moreover, the transition of switching dynamics is responsible for the faster speed and better endurance of the composition-graded HZO thin film. These findings not only reveal the physical mechanisms of this material system but also provide a new strategy for memory devices having faster speed and higher endurance.     

A new ferroelectric memory device, metal-ferroelectric-semiconductor transistor

The ferroelectric field effect has successfully been demonstrated on a bulk semiconductor (silicon) using a thin ferroelectric film of bismuth titanate (Bi4Ti3O12) deposited onto it by RF sputtering. A new memory device, the metal-ferroelectric-semiconductor transistor (MFST); has been fabricated. This device utilizes the remanent polarization of a ferroeletric thin film to control the surface conductivity of a bulk semiconductor substrate and perform a memory function. The capacitance-voltage characteristics of the metal-ferroelectric-semiconductor structure were employed to study the memory behavior. The details of the study together with a preliminary results on the MFST are presented.     

压电和铁电薄膜及其应用的发展趋势

本文讨论了压电和铁电薄膜材料及其在固体器件中应用的发展趋势。薄膜生长技术的进展,为压电和铁电薄膜集成固体器件在各个领域的应用开辟了广阔的前景。ZnO和AIN薄膜将广泛地用于SAW和BAW器件。特别是成功地制作了薄膜体声波谐振器和高次谐波体波谐振器。以PbTiO_3为基的PZT和PLZT固溶体外延薄膜将应用于热电探测器和SAW器件。在实现了对多层薄膜的界面结构及其特性的成功控制之后,铁电薄膜将在铁电存储和集成光学领域发挥重要作用。     

铁电负电容场效应晶体管器件的研究

铁电负电容场效应晶体管作为一种新型半导体器件,利用铁电材料的负电容效应可使晶体管的亚阈值摆幅突破理论极限值60 mV/dec,是未来低功耗晶体管领域最具有前途的器件之一。该文研究并建立了铁电负电容场效应晶体管的器件模型,采用Matlab软件对负电容场效应晶体管的器件特性进行了研究分析,获得了亚阈值摆幅为33.917 6 mV/dec的负电容场效应晶体管的器件结构,探究了铁电层厚度、等效栅氧化层厚度及不同铁电材料对负电容场效应晶体管亚阈值摆幅的影响。     

Reconfigurable Physical Reservoir Enabled by Polarization of Ferroelectric Polymer P(VDF–TrFE) and Interface Charge-Trapping/Detrapping in Dual-Gate IGZO Transistor

Neuromorphic computers promise to enhance computing efficiency by eliminating conventional von Neumann architecture bottlenecks. Bio-inspired artificial neural networks, such as feedforward neural networks and reservoir computing (RC), face challenges due to the unique memristor requirements. In this study, a dual-gate ferroelectric polymer P(VDF–TrFE)-coupled thin film transistor (DG–TFT) with an IGZO channel is presented. It yields complementary short- and long-term memory functionalities are derived from the charge-trapping/detrapping process at the IGZO-SiO₂ dielectric interface and ferroelectric polarization. These memory functionalities can be switched using different gated modes to meet the requirements of the reservoir and readout layers in RC. The bottom-gated mode (BG-mode) exhibits short-term memory effects and nonlinear dynamics, whereas the top-gated mode (TG-mode) displays improved long-term memory characteristics. To evaluate the long-term memory properties, Python is used for pattern recognition. For the nonlinear dynamics and short-term memory response of the BG-mode, the DG–TFT is employed as a reservoir layer to handle various temporal tasks. Notably, the polarization level of the ferroelectric layer is coupled to improve the richness of the reservoir states, providing a reconfigurable RC system with an expanded capacity to effectively process and accommodate diverse signals. This holds potential for next-generation hybrid intelligent applications.