Analysis And Implementation Of CD Uniformity In TFT-LCD Array Lithography Process

Photolithography process is the key part of TFT manufacture.The shape size of TFT device is completely determined by the photolithography technique.With the continuous improvement of demand for the response time,color saturation,energy consumption,and distinguishability of TFT-LCD,especially improvement of distinguishability,the line width and interval of TFT device intend to be thinner and narrower,respectively.Besides,the process window of shaped critical dimension line width(CD-line width)after the photolithography process is becoming increasingly smaller and the control requirements of TFT are becoming increasingly rigorous.The line width of final shaped TFT device would be directly influenced on condition that the CD of products deviate control target value.Consequently,the optical and electronic performance of TFT products would be influenced.Starting from the development history of display technology,this paper analyzes the development trend and challenges of domestic TFT-LCD.This paper also analyzes the display mechanism of TFT-LCD and the photolithography process which is the key process of TFT.Then the conclusion is that homogeneity of CD is a key point to improve the performance of TFT-LCD.In the photolithography process,through changing coating,photolithography,development,prebake and post-bake process,the homogeneity of CD of photolithography process could be improved.In this thesis,the main research contents are as follows:(1)Through reviewing the development history of display technology,it is concluded that TFT-LCD flat panel display technology is still the mainstream.Then,the development trend of display technology in China and abroad is analyzed,and the opportunities and challenges of display technology in China are summed up.The necessity of low generation TFT line to improve product competitiveness and improve homogeneity of CD after lithography is introduced.(2)According to research of the drive principle,display principle of colors and main display performance index of the TFT-LCD,the key technical indicators that affect TFT-LCD performance is understood.The subsequent performance analysis is improved and it makes advanced theoretical bedding.(3)The analysis and research of TFT lithography process is based on the current traditional five masks lithography process.Key performance indicators for the main processes of photolithography and key materials used,such as photoresist(PR),developer(TMAH)and Thinner,are systematically introduced to make a paving for subsequent improvements.(4)The photoresist coating process that affects the homogeneity of CD in lithography process,the pre baking unit and the developing unit are tested,and the relevant change rules are analyzed and summarized.According to the rules,the technological process is improved and the homogeneity of CD in lithography process is finally improved.So as to improve the performance of the product and improve the product quality and competitiveness of low generation line.