柔性铟镓锌氧化物半导体材料及器件特性仿真

发布时间：2018-04-16 05:12

本文选题：IGZO + C-V曲线　；参考：《电子科技大学》2015年硕士论文

【摘要】：柔性半导体器件凭借其可弯曲、低成本、低功耗、生产简易性和规模化等突出优势而存在广阔的应用前景,如曲面显示、智能标签、小型计算芯片、可穿戴设备等,为用户带来全新的体验。柔性半导体器件需要由柔性材料制成,其中铟镓锌氧化物(Indium Gallium Zinc Oxide,即IGZO)是制造柔性半导体器件的主要材料之一。尽管目前柔性IGZO薄膜场效应管(Thin Film Transistors,TFT)尚未实现批量生产,但是此种器件容易与现有工艺实现兼容,且具有广阔的应用前景,因此国际上对IGZO柔性半导体器件进行了深入而广泛的研究。为了更好的将IGZO-TFT应用到各种产品中,有必要对该器件的性质进行深入的研究。其中电容-偏压特性(C-V特性)作为半导体器件的基本特性之一,能够在一定程度上表征器件的性质。一般情况下MOS结构半导体器件的栅电极与源极或漏极之间会存在电容,电容会随栅极电压的变化而改变,变化过程可用C-V特性曲线描述。MOS结构的C-V特性能够表征器件的载流子浓度分布,陷阱在器件内的分布、时间常数及陷阱能级的位置,以及放大器的频率特性。IGZO器件与MOS结构有相似之处,但是由于其材料的特殊性质,其低频C-V曲线不存在反型区。因此有必要对IGZO器件的C-V特性进行深入的研究。本文主要仿真研究了IGZO器件的C-V特性,具体研究内容如下:首先对柔性材料IGZO的电学性质进行分析,其中重点分析其载流子特性,通过计算表明该材料的本征载流子浓度很低,为10-15cm-3量级,根据该结论得到了沟道电子浓度与偏压的关系,并建立仿真模型;其次,详细论述了IGZO薄膜场效应管的常见结构——背栅结构,根据对称性将仿真过程简化,并根据有限差分原理划分了器件的仿真单元;然后,根据矩阵形式的二维泊松方程,利用奇异值分解处理,求出器件的二维电势分布,为了进一步分析器件的C-V特性,在上述结果的基础上,求解交流形式的二维泊松方程,得出了一定小信号频率下器件的二维电势分布;最后,通过电容的阻抗模型,仿真得出器件的C-V特性,在不同频率下该仿真结果与已报导的实验结果基本一致,并通过交流电势幅值与相位的二维分布,分析得出该结构的高低频电容在积累区的差异主要由于IGZO材料载流子浓度低,电阻率较高。
[Abstract]:Flexible semiconductor devices have broad application prospects because of their outstanding advantages such as bending, low cost, low power consumption, ease of production and scale, such as curved surface display, intelligent labels, small computing chips, wearable devices, etc.Bring new experience to users.Flexible semiconductor devices need to be fabricated from flexible materials. Indium Gallium Zinc oxide (IGZO) is one of the main materials for manufacturing flexible semiconductor devices.Although the thin Film transistors TFT (thin Film transistors) have not been produced in batches, this kind of device is easy to be compatible with the existing technology and has a wide application prospect.Therefore, IGZO flexible semiconductor devices have been studied deeply and extensively in the world.In order to better apply IGZO-TFT to all kinds of products, it is necessary to study the properties of the device.As one of the basic characteristics of semiconductor devices, capacitance-bias characteristic (C-V) can characterize the properties of semiconductor devices to a certain extent.In general, there is a capacitance between the gate electrode and the source or drain of the MOS semiconductor device, and the capacitance changes with the change of the gate voltage.The C-V characteristic of MOS structure can describe the carrier concentration distribution, trap distribution in the device, time constant and the position of trap energy level.The frequency characteristics of the amplifier. IGZO devices are similar to the MOS structure, but because of the special properties of the material, there is no inverse region in the low frequency C-V curve.Therefore, it is necessary to study the C-V characteristics of IGZO devices.In this paper, the C-V characteristics of IGZO devices are simulated and studied. The main contents are as follows: firstly, the electrical properties of the flexible material IGZO are analyzed, and the carrier characteristics are emphatically analyzed. The calculation results show that the intrinsic carrier concentration of the material is very low.According to the conclusion, the relationship between channel electron concentration and bias voltage is obtained, and the simulation model is established. Secondly, the common structure of IGZO thin film FET, the back gate structure, is discussed in detail, and the simulation process is simplified according to the symmetry.According to the finite difference principle, the simulation unit of the device is divided, and then, according to the two-dimensional Poisson equation in matrix form, the two-dimensional potential distribution of the device is obtained by using singular value decomposition, in order to further analyze the C-V characteristic of the device.On the basis of the above results, the two-dimensional Poisson equation in AC form is solved, and the two-dimensional potential distribution of the device at a certain small signal frequency is obtained. Finally, the C-V characteristic of the device is simulated by the impedance model of the capacitance.The simulation results are basically consistent with the reported experimental results at different frequencies. Through the two-dimensional distribution of the amplitude and phase of AC potential, it is found that the difference of the high and low frequency capacitance of the structure in the accumulative region is mainly due to the low carrier concentration of the IGZO material.The resistivity is higher.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN304.2

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