负电容PZT铁电场效应晶体管的物理模型与性能优化

发布时间：2018-11-12 15:08

【摘要】：近些年来,铁电场效应晶体管得到了人们广泛的关注与研究,它被用作铁电存储器的存储单元,而铁电存储器由于其优良的特性(存储速度快、不易挥发、与集成电路工艺兼容、功耗低等)被认为是下一代比较理想的存储器之一。随着芯片集成度的不断提高,功耗成为人们面临的一个严峻问题,当铁电场效应晶体管用作铁电存储器芯片自然也需要克服功耗问题,而研究表明,铁电场效应晶体管的负电容效应可以有效的降低晶体管的功耗。基于此,本文通过物理建模、数值分析,重点研究铁电场效应晶体管的负电容效应。研究的主要内容及结论如下:1.基于Landau-Ginzburg-Devonshire唯象理论、泊松方程以及电流连续性方程,建立负电容PZT(PbZr1-xTixO3)双栅场效应晶体管的物理模型,并分析锆钛比对其电学性能的影响,结果表明:钛的比率对负电容PZT铁电栅场效应晶体管的电学性能有一定的影响;当钛的比率减小(0.065~0.035)时,由于铁电材料的负电容效应,栅电容得到放大,硅表面势放大能力增强,亚阈值摆幅降低,从而达到降低功耗的目的。该研究结果为解决铁电场效应晶体管的功耗问题提供了新途径;对其在快速开关方面的应用也有一定的意义。2.根据第2章的物理模型,研究、分析不同铁电层厚度时,负电容PZT双栅场效应晶体管的电学性能,我们得到了以下结论:在一定范围内(120~200nm),通过增大铁电层厚度可以增强负电容效应,增强硅表面势放大能力,降低亚阈值摆幅,实现晶体管的低功耗操作。该结果为优化负电容铁电场效应晶体管的电学性能有较好的指导意义。3.根据第2章的物理模型,研究绝缘层厚度对负电容PZT双栅场效应晶体管电学性能的影响。通过计算、分析,可以得到以下结论:随着绝缘层厚度的增大(2~4 nm),电压放大能力变差,栅电容尖峰减小,亚阈值特性变差。我们可以通过减小绝缘层厚度来提高电压放大能力,增强负电容效应,降低晶体管功耗。该结果提供了一种解决铁电场效应晶体管功耗问题的新途径。4.根据第2章的物理模型,研究半导体硅厚度对负电容PZT双栅场效应晶体管电学性能的影响。通过计算、分析,可以得到以下结论:半导体硅厚度对铁电负电容效应的影响非常小,可以忽略不计。因而,我们在考虑铁电负电容的影响因素时,可以忽略半导体硅厚度对负电容的影响,该结果可以为铁电场效应晶体管的设计提供一定的理论指导。
[Abstract]:In recent years, ferroelectric field effect transistors have been paid more and more attention. They are used as memory cells of ferroelectric memory, and ferroelectric memory is easy to volatilize because of its excellent characteristics. It is considered to be one of the most ideal memory for the next generation. With the continuous improvement of chip integration, power consumption has become a serious problem that people face. When ferroelectric field effect transistors are used as ferroelectric memory chips, power consumption problems naturally need to be overcome. The negative capacitance effect of the ferroelectric field effect transistor can effectively reduce the power consumption of the transistor. Based on this, the negative capacitance effect of ferroelectric field effect transistors is studied by physical modeling and numerical analysis. The main contents and conclusions are as follows: 1. Based on Landau-Ginzburg-Devonshire phenomenological theory, Poisson equation and current continuity equation, the physical model of negative capacitance PZT (PbZr1-xTixO3) double gate field effect transistor is established, and the influence of zirconium titanium ratio on its electrical properties is analyzed. The results show that the ratio of titanium has a certain influence on the electrical properties of the negative capacitance PZT ferroelectric gate field effect transistor. When the titanium ratio decreases (0.065 ~ 0.035), the gate capacitance is amplified because of the negative capacitance effect of ferroelectric material, the potential amplification ability of silicon surface is enhanced, and the sub-threshold swing is reduced, thus the power consumption is reduced. The results provide a new way to solve the problem of power consumption of ferroelectric field effect transistors, and have a certain significance for its application in fast switching. 2. According to the physical model in Chapter 2, the electrical properties of negative capacitance PZT double gate field effect transistors with different thickness of ferroelectric layer are studied. The following conclusions are obtained: within a certain range (120~200nm), By increasing the thickness of the ferroelectric layer, the negative capacitance effect can be enhanced, the amplification ability of silicon surface potential can be enhanced, the sub-threshold swing can be reduced, and the low power operation of the transistor can be realized. The results are of great significance for the optimization of the electrical properties of the negative capacitive ferroelectric field effect transistors. 3. Based on the physical model in chapter 2, the influence of the thickness of insulation layer on the electrical properties of negative capacitance PZT double gate field effect transistors is studied. Through calculation and analysis, the following conclusions can be obtained: with the increase of the thickness of the insulation layer (2n4 nm), voltage amplification ability becomes worse, the peak of gate capacitance decreases, and the subthreshold characteristic becomes worse. We can increase the voltage amplification ability, enhance the negative capacitance effect and reduce the power consumption of the transistor by reducing the thickness of the insulation layer. This result provides a new way to solve the power problem of ferroelectric field effect transistors. 4. Based on the physical model in Chapter 2, the effect of semiconductor silicon thickness on the electrical properties of negative capacitor PZT double-gate field-effect transistors is studied. Through calculation and analysis, the following conclusions can be drawn: the influence of semiconductor silicon thickness on ferroelectric negative capacitance effect is very small and can be ignored. Therefore, when we consider the influence factors of ferroelectric negative capacitance, we can ignore the influence of semiconductor silicon thickness on negative capacitance, which can provide some theoretical guidance for the design of ferroelectric field effect transistor.
【学位授予单位】：湘潭大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN386

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