薄膜晶体管液晶显示器的串扰研究
发布时间：2018-08-02 17:47
【摘要】：随着薄膜晶体管液晶显示器(TFT-LCD)的迅速发展,产品高分辨率、广视角、高响应速度、高开口率等需求对器件的显示质量提出了更高的要求。而伴随着像素尺寸变小,线间距越来越小,当信号线上有电流通过时,线间感应电场的干扰变得尤为突出,像素之间的耦合加剧,这些都会导致串扰现象的发生,大大影响了产品良率和效益。所以串扰对TFT-LCD来说,是一个亟待解决的重大问题。 首先,文章从TFT-LCD的基本结构、工作原理及工艺制程出发,通过分析在不同极性反转情况下,TFT-LCD内共电极、像素电极和数据线上的波形,及它们之间的耦合影响,找到了水平串扰和垂直串扰产生的原因。其中水平串扰产生的原因主要是共电极延迟,垂直串扰产生的原因包括像素电极与数据线之间的耦合以及TFT漏电。 其次,(1)针对水平串扰产生的原因,进行了不同厚度下的ITO电阻模拟,研究了ITO厚度对共电极延迟的影响；得出了减小共电极延迟的方法：设计上需增大Vcom ITO线宽、减小数据线线宽；工艺上需增加Vcom ITO电极和钝化层的厚度或采用方块电阻更小电极材料和介电常数更小的钝化层。(2)针对垂直串扰产生的原因,模拟了正对位和对位偏移时数据线和像素电极之间的耦合电容Cpd,研究了对位偏移对串扰值的影响；探索了最佳TFT关断电压VGL,进行了光照和温度对漏电流的影响的实验。通过这些研究得出：①减小耦合电容Cpd的方法：设计上要保证数据线与像素ITO之间的距离为6μm以上(其中包含了2.5μm的工艺波动),保证数据线与Vcom ITO之间距离为3.5μm以上(其中包含了2.5μm的工艺波动)；使用新的像素结构,即在数据线上方增加一体化的遮挡层(适用于TN型TFT-LCD)、或树脂层(适用于IPS型TFT-LCD),以及在像素扫描线另一端增加金属Vcom线。工艺上要严格管控像素ITO、数据线、Vcom线之间的对位精度。②减小漏电的方法：设计上,需减小有源层面积,使其被包裹在栅极基台内；将栅极关断电压设置为-10.5V左右；或采用双有源层结构、双栅结构来提高TFT的关态特性。工艺上,需严格管控有源层在工艺上的偏移。
[Abstract]:With the rapid development of thin-film transistor liquid crystal display (TFT-LCD), the demand of high resolution, wide viewing angle, high response speed and high opening rate puts forward higher requirements for the display quality of the device. As the pixel size becomes smaller and the line spacing becomes smaller and smaller, the interference of the inductive electric field between the lines becomes particularly prominent when the current is passing on the signal line, and the coupling between the pixels becomes more and more serious, which will lead to crosstalk. The product yield and benefit are greatly affected. So crosstalk is an important problem to be solved urgently for TFT-LCD. First of all, based on the basic structure, working principle and process of TFT-LCD, this paper analyzes the waveforms of coelectrode, pixel electrode and data line in TFT-LCD under different polarity reversal conditions, and the coupling effect between them. The causes of horizontal crosstalk and vertical crosstalk are found. The main causes of horizontal crosstalk are common electrode delay and vertical crosstalk is caused by coupling between pixel electrode and data line and TFT leakage. Secondly, (1) aiming at the cause of horizontal crosstalk, we simulate the ITO resistance at different thickness, study the influence of ITO thickness on the co-electrode delay, and obtain the method to reduce the co-electrode delay: the design needs to increase the Vcom ITO linewidth. Reducing the line width of the data line; increasing the thickness of the Vcom ITO electrode and the passivation layer in a process or using a smaller sheet resistance electrode material and a passivated layer with a smaller dielectric constant. (2) for the causes of vertical crosstalk, The coupling capacitance Cpdd between the data line and the pixel electrode during positive and opposite bit offset is simulated, the effect of the pair offset on crosstalk value is studied, the optimal switching off voltage of TFT is explored, and the effects of illumination and temperature on leakage current are studied. Through these studies, it is concluded that the method of reducing coupling capacitance Cpd by 1: 1 is designed to ensure that the distance between the data line and the pixel ITO is more than 6 渭 m (which contains the process fluctuation of 2.5 渭 m), and the distance between the data line and the Vcom ITO is 3.5 渭 m. Above (including 2.5 渭 m process fluctuation); A new pixel structure is used, that is, an integrated occlusion layer (for TN type TFT-LCD) or resin layer (for IPS type TFT-LCD) is added over the data line, and a metal Vcom line is added at the other end of the pixel scan line. In technology, the pixel ITO should be strictly controlled. The method of reducing the leakage current between the data lines and Vcom lines is as follows: in design, the area of the active layer should be reduced so that it can be wrapped in the grid base station, the turn-off voltage of the grid should be set to -10.5V; Or double active layer structure and double gate structure are used to improve the off state characteristics of TFT. Process, the need to strictly control the active layer in the process of deviation.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN873.93
[Abstract]:With the rapid development of thin-film transistor liquid crystal display (TFT-LCD), the demand of high resolution, wide viewing angle, high response speed and high opening rate puts forward higher requirements for the display quality of the device. As the pixel size becomes smaller and the line spacing becomes smaller and smaller, the interference of the inductive electric field between the lines becomes particularly prominent when the current is passing on the signal line, and the coupling between the pixels becomes more and more serious, which will lead to crosstalk. The product yield and benefit are greatly affected. So crosstalk is an important problem to be solved urgently for TFT-LCD. First of all, based on the basic structure, working principle and process of TFT-LCD, this paper analyzes the waveforms of coelectrode, pixel electrode and data line in TFT-LCD under different polarity reversal conditions, and the coupling effect between them. The causes of horizontal crosstalk and vertical crosstalk are found. The main causes of horizontal crosstalk are common electrode delay and vertical crosstalk is caused by coupling between pixel electrode and data line and TFT leakage. Secondly, (1) aiming at the cause of horizontal crosstalk, we simulate the ITO resistance at different thickness, study the influence of ITO thickness on the co-electrode delay, and obtain the method to reduce the co-electrode delay: the design needs to increase the Vcom ITO linewidth. Reducing the line width of the data line; increasing the thickness of the Vcom ITO electrode and the passivation layer in a process or using a smaller sheet resistance electrode material and a passivated layer with a smaller dielectric constant. (2) for the causes of vertical crosstalk, The coupling capacitance Cpdd between the data line and the pixel electrode during positive and opposite bit offset is simulated, the effect of the pair offset on crosstalk value is studied, the optimal switching off voltage of TFT is explored, and the effects of illumination and temperature on leakage current are studied. Through these studies, it is concluded that the method of reducing coupling capacitance Cpd by 1: 1 is designed to ensure that the distance between the data line and the pixel ITO is more than 6 渭 m (which contains the process fluctuation of 2.5 渭 m), and the distance between the data line and the Vcom ITO is 3.5 渭 m. Above (including 2.5 渭 m process fluctuation); A new pixel structure is used, that is, an integrated occlusion layer (for TN type TFT-LCD) or resin layer (for IPS type TFT-LCD) is added over the data line, and a metal Vcom line is added at the other end of the pixel scan line. In technology, the pixel ITO should be strictly controlled. The method of reducing the leakage current between the data lines and Vcom lines is as follows: in design, the area of the active layer should be reduced so that it can be wrapped in the grid base station, the turn-off voltage of the grid should be set to -10.5V; Or double active layer structure and double gate structure are used to improve the off state characteristics of TFT. Process, the need to strictly control the active layer in the process of deviation.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN873.93
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