Research And Analysis Of Nikon Exposure Lens Mura

With the development of science and technology,various products based on thin film transistor liquid crystal display(TFT-LCD)devices,such as televisions,monitors,business displays,exhibition displays,and shopping shelf displays,have long been integrated into people's lives.Among them,TV is one of the most important applications of large-scale TFT-LCD(commonly known as LCD TV),showing a trend of large screen and high definition.At present,the mainstream size of TV panels in the Chinese mainland market has slowly shifted from 55 inchs to 65 inches.The main panel production of more than 65 inches TV will be provided by a few manufacturers who have laid out G10 LCD panel production plants.At present,only Nikon can provide the exposure machine of the G10 production line,and the Nikon exposure machine has a congenital deficiency based on its imaging design,that the panel produced will have Lens mura.Mura is a kind of bad phenomenon that affects the picture quality of LCD TVs.It mainly shows that the brightness or color display in the effective display area is uneven,which will directly affect the display quality of the product.With the continuous understanding of liquid crystal display technology,consumers are increasingly demanding the display quality of LCD TVs.These higher image quality requirements have prompted LCD panel makers to minimize the impact of Mura through product design optimization,process improvement,etc.,while in large-size TV panels,Lens Mura bears the brunt.This thesis aims to explore the formation mechanism of Lens Mura by analyzing the structure and imaging principle of Nikon exposure machine image system,and find out the relevant factors affecting its strong and weak performance through design experiments,and formulate the improvement plan of each relevant factor and pass the experiment,to verify the feasibility of the improvement program.In this thesis,the problem of product quality is affected by the presence of lens mura in the TFT-LCD panel produced by Nikon exposure machine.By analyzing the structure and imaging principle of Nikon exposure machine image system,the ITO CD change of adjacent lens at different dislocation levels and the limitations of the existing non-linear exposure accuracy control methods of Nikon exposure machines are studied.The results show that the direct cause of the formation of lens mura is that in the case of misalignment of the adjacent lens,there is a weak exposure phenomenon on the two sides of the original pattern with the same size of the adjacent lens junction area.The size of the imaging misalignment at the midpoint can be directly measured by designing a misalignment imaging experiment,thereby providing a way to improve the coincidence accuracy of the midpoints in the adjacent lens junction zone.In addition,in view of the weak exposure phenomenon mentioned above,by analyzing the influence of each process parameter on the exposure dose value in the photo process,the design experiment confirms the difference in the performance effect of the lens mura caused by the change of the process conditions upstream and downstream of the exposure machine.Using the control variable method,the effects of three key parameters,photoresist film thickness,soft baking temperature and development time on the CD change in weak exposure area were studied.The results show that the condition setting of the photo process is an indirect cause of the formation of lens mura: when the dose value required for exposure is increased by the adjustment of the process parameters,the weak exposure effect will be weakened and the lens mura will be correspondingly weakened.The effects of photoresist film thickness,soft baking temperature and development time on CD changes under specific basic process conditions are:1.When the thickness of the photoresist film is thickened from 1.4?m,the CD change slightly decrease at the beginning,but the improvement is not obvious,and as the film thickness continues to increase,the CD change can continue to convergence,but the improvement continues to slow down.2.When the soft baking temperature starts to increase from 110 °C,the CD change shows a linear tendency to decrease slightly.It is speculated that as the soft baking temperature continues to increase,the CD change may continue to convergence.3.When the development time decreases from 70 s,the CD change decreases linearly and slightly.It is speculated that as the development time continues to decrease,the CD change may continue to decrease,and when the development time rises from 70 s,a trend of rapid CD change increase is presented.This thesis not only invents a method to improve the imaging accuracy of the adjacent lens junction area of Nikon exposure machine,but also provides an effective basis and direction for optimizing the process parameters of each unit in the photo process and weakening the influence of lens mura.It provides a powerful basis for the subsequent industry improvement of lens mura's process adjustment program,reducing the unnecessary parameter debugging,and also greatly improving the image quality of related products,presenting a more refined display world to consumers.