非晶IGZO薄膜晶体管与基本电路研究

发布时间：2018-05-11 02:15

本文选题：非晶铟镓锌氧基薄膜晶体管 + 反相器　；参考：《南京大学》2015年硕士论文

【摘要】：以平板显示为代表的现在显示主要有两种技术手段,一种是基于含氢非晶硅薄膜晶体管(a-Si:HTFT)作为驱动解决方案的;另一种是基于低温多晶硅薄膜晶体管(low temperature poly-silicon, LTPS TFT)作为驱动解决方案。目前主流的平板显示器如有源矩阵液晶显示器(Active Matrix liquid crystal Display, AMLCD)和有源矩阵有机发光二极管显示器(Active Matrix Organic Light-emitting Display, AMOLED)多是采用这两种驱动方式。在当今信息社会的高速发展下,这两种驱动方式越来越不能满足人们日益增长的显示要求的需要,例如更快的响应速度,更大尺寸的显示面板,更低的功耗等。透明氧化物基薄膜晶体管由于具有较好的电学和光学特性,在下一代显示产业中极具应用前景,因而受到广泛的关注。特别由于非晶铟镓锌氧基薄膜晶体管(a-IGZO TFT)具有较高的场效应迁移率、高的光学透过率、低的漏电流、低的生长温度以及低成本等优点而被广泛研究,以期取代a-Si:H TFT和LTPS TFT,分别应用在AMLCD和AMOLED显示上。尽管a-IGZO TFT分立器件表现出较好的静态特性,但是用来制备大尺寸面板的像素驱动电路和外围驱动电路就需要研究器件的动态特性。所以,本文的工作主要是基于a-IGZO TFTs制备出简单的逻辑电路,并对电路的基本性能进行表征,主要内容如下：1.在玻璃衬底上同时制备了底栅结构的a-IGZO TFT器件和增强型饱和负载反相器。其中,单个a-IGZO TFT表现出了较好的器件特性,例如场效应迁移率为5 cm2/Vs,开启电压为3V,亚闽值摆幅为0.5V/dec;根据NMOS逻辑原理设计的增强型饱和负载反相器是由相同沟道长度,不同沟道宽度的负载TFT和驱动TFT构成。通过测试a-IGZO TFT基反相器的电压转移特性曲线,发现反相器表现出了从1V到27 V的摆幅区间,接近全摆幅的85%。而且,较宽的输出摆幅也提高了反相器的噪声容限能力。另外,反相器的电压增益达到-6 V/V,这表明反相器实现了较好的逻辑电平转换功能。2.在玻璃衬底上制备了基于a-IGZO TFT基的7阶环形振荡器。7阶环形振荡器电路由7个相同的延迟阶反相器和1个输出缓冲阶反相器组成。构成7阶环形振荡器的单个反相器表现出了较好的逻辑电平转换功能。通过测试环形振荡器的动态特性对外加电压和栅极长度的依赖关系,发现随着外加电压的增加,环形振荡器的振荡频率会随之增加,单阶传播延迟时间有所减少。另外,栅极长度越短,环形振荡器的振荡频率越高,采用4μm的沟道长度的7阶环形振荡器电路在40 V的外加偏压下,振荡频率达到1.47 MHz,相应的单阶传播延迟时间低于50 ns/stage。
[Abstract]:There are mainly two kinds of technology for flat panel display. One is based on a-Si: HTFT, a hydrogen-containing amorphous silicon thin film transistor. The other is based on low temperature polysilicon thin film transistor low temperature poly-silicon (LTPS TFT) as the driving solution. At present, active Matrix liquid crystal Display, AMLCD) (active Matrix liquid crystal Display, AMLCD) and active Matrix Organic Light-emitting display (AMOLED) are widely used in the mainstream flat panel displays such as active matrix liquid crystal display (LCD) and active matrix organic light-emitting diode (AMOLED) displays. With the rapid development of information society, these two driving methods can not meet the increasing demand of display, such as faster response speed, larger display panel, lower power consumption and so on. Due to its good electrical and optical properties, transparent oxide based thin film transistors have attracted wide attention due to their potential applications in the next generation display industry. Especially, amorphous indium gallium zinc oxide based thin film transistors, such as high field effect mobility, high optical transmittance, low leakage current, low growth temperature and low cost, have been widely studied. In order to replace a-Si:H TFT and LTPS TFT, they can be used on AMLCD and AMOLED display, respectively. Although the a-IGZO TFT discrete devices exhibit good static characteristics, the dynamic characteristics of the devices need to be studied for the pixel drive circuits and peripheral drive circuits used to fabricate the large size panel. Therefore, the main work of this paper is to prepare a simple logic circuit based on a-IGZO TFTs, and to characterize the basic performance of the circuit, the main content is as follows: 1. A-IGZO TFT devices with bottom gate structure and enhanced saturated load inverters were fabricated on glass substrate. For example, the field effect mobility is 5 cm ~ 2 / V ~ s, the opening voltage is 3 V, the sub-threshold swing is 0.5 V / R, and the enhanced saturated load inverter designed according to the NMOS logic principle is of the same channel length. Load TFT and driver TFT with different channel width. By testing the voltage transfer characteristic curve of the a-IGZO TFT based inverter, it is found that the phase inverter shows a swing range from 1 V to 27 V, which is close to the full swing. Moreover, the wider output swing also improves the noise tolerance of the inverter. In addition, the voltage gain of the inverter reaches 6 V / V, which shows that the inverter achieves a better logic level conversion function. 2. A 7-order ring oscillator based on a-IGZO TFT is fabricated on glass substrate. The circuit consists of seven identical delay order inverters and one output buffer phase inverter. A single inverter composed of a 7 th order ring oscillator exhibits a good logic level conversion function. By testing the dependence of the dynamic characteristics of the ring oscillator on the applied voltage and the gate length, it is found that with the increase of the applied voltage, the oscillation frequency of the ring oscillator increases and the single order propagation delay time decreases. In addition, the shorter the gate length is, the higher the oscillation frequency of the ring oscillator is. The oscillation frequency of the 7 order ring oscillator circuit with channel length of 4 渭 m is 1.47 MHz under the applied bias voltage of 40 V, and the corresponding single-order propagation delay time is less than 50 ns / r 路s.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN321.5

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