薄膜晶體管液晶顯示器的串擾研究
發(fā)布時間：2018-08-02 17:47
【摘要】：隨著薄膜晶體管液晶顯示器(TFT-LCD)的迅速發(fā)展,產品高分辨率、廣視角、高響應速度、高開口率等需求對器件的顯示質量提出了更高的要求。而伴隨著像素尺寸變小,線間距越來越小,當信號線上有電流通過時,線間感應電場的干擾變得尤為突出,像素之間的耦合加劇,這些都會導致串擾現象的發(fā)生,大大影響了產品良率和效益。所以串擾對TFT-LCD來說,是一個亟待解決的重大問題。 首先,文章從TFT-LCD的基本結構、工作原理及工藝制程出發(fā),通過分析在不同極性反轉情況下,TFT-LCD內共電極、像素電極和數據線上的波形,及它們之間的耦合影響,找到了水平串擾和垂直串擾產生的原因。其中水平串擾產生的原因主要是共電極延遲,垂直串擾產生的原因包括像素電極與數據線之間的耦合以及TFT漏電。 其次,(1)針對水平串擾產生的原因,進行了不同厚度下的ITO電阻模擬,研究了ITO厚度對共電極延遲的影響；得出了減小共電極延遲的方法：設計上需增大Vcom ITO線寬、減小數據線線寬；工藝上需增加Vcom ITO電極和鈍化層的厚度或采用方塊電阻更小電極材料和介電常數更小的鈍化層。(2)針對垂直串擾產生的原因,模擬了正對位和對位偏移時數據線和像素電極之間的耦合電容Cpd,研究了對位偏移對串擾值的影響；探索了最佳TFT關斷電壓VGL,進行了光照和溫度對漏電流的影響的實驗。通過這些研究得出：①減小耦合電容Cpd的方法：設計上要保證數據線與像素ITO之間的距離為6μm以上(其中包含了2.5μm的工藝波動),保證數據線與Vcom ITO之間距離為3.5μm以上(其中包含了2.5μm的工藝波動)；使用新的像素結構,即在數據線上方增加一體化的遮擋層(適用于TN型TFT-LCD)、或樹脂層(適用于IPS型TFT-LCD),以及在像素掃描線另一端增加金屬Vcom線。工藝上要嚴格管控像素ITO、數據線、Vcom線之間的對位精度。②減小漏電的方法：設計上,需減小有源層面積,使其被包裹在柵極基臺內；將柵極關斷電壓設置為-10.5V左右；或采用雙有源層結構、雙柵結構來提高TFT的關態(tài)特性。工藝上,需嚴格管控有源層在工藝上的偏移。
[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.
【學位授予單位】：北京交通大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：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.
【學位授予單位】：北京交通大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TN873.93
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