AMOLED (AcTIve Matrix/Organic Light EmitTIng Diode) is an active matrix organic light emitting diode panel. Compared with traditional liquid crystal panels, AMOLED has the characteristics of faster response, higher contrast, and wider viewing angle. Because AMOLED has inherent advantages over TFT LCD in terms of image quality, performance and cost. This is why many international companies still do not give up developing AMOLEDs despite their difficult yield. At present, we continue to invest in the development of AMOLED manufacturers, in addition to Sony, which has already announced the time to market, Toshiba, which invests in Toshiba Matsushita Display (TMD), and Panasonic, which has separately developed products, and Sharp, which claims to be not optimistic. The NOKIA N85 released in August 2008 and the NOKIA N86 launched in the first quarter of 2009 all use AMOLED. In terms of display performance, AMOLED has faster response speed, higher contrast ratio and wider viewing angle. These are places where AMOLED is better than TFT LCD. In addition, AMOLED has self-illuminating features, no need to use backlight, so it is more than TFT. It can be made thinner and more power efficient. There is also a more important feature. AMOLED without backlighting can save the cost of backlight module which accounts for 3~4% of TFT LCD. AMOLED is indeed a very attractive product. Many international manufacturers like it. Even the iPhone, the most popular product in the mobile phone market, is interested in AMOLED. I believe that after the yield increase, the iPhone will also consider adopting AMOLED, especially AMOLED. The characteristics of power saving are very suitable for mobile phones. At present, the power consumption of AMOLED panels is only about 60% of TFT LCD, and there is room for further decline in future technologies. Of course, the biggest problem with AMOLED is the yield. At the current yield, the price of AMOLED panels is 50% higher than that of TFT LCD. This is a threshold for customers to use a lot, but for Qijing, now The stage is also in the training period of the adjustment rate, and it is not easy to take orders in large quantities. (1) Metal oxide TFT This production technology is currently favored by many manufacturers and professional survey companies, and is considered to be the first choice for large-size AMOLED technology routes in the future. Each company also has corresponding large-size samples on display. The TFT substrate of the technology can adopt a mature and large-scale sputtering film formation method in the liquid crystal industry, and the oxide is InGaO3 (ZNO) 5, although the electron mobility of the device is higher than that of the LTPS technology. The product is low, basically 10 cm2/V-sec, but this mobility parameter is more than 10 times that of the amorphous silicon technology device. The electron mobility of the device can fully meet the current driving requirements of AMOLED, so it can be applied to OLED. Drive. At present, metal oxide technology is still in the laboratory verification stage. There is no real experience of overproduction in the world. The main factor is that its reproducibility and long-term work stability need further improvement and confirmation. (2) Low temperature polysilicon technology (LTPS TFT) This technology is currently the only AMOLED production technology in the world that has been commercialized and mass-produced and proven to be quite mature in the production line below G4.5. The main difference between this technology and amorphous silicon technology is the use of laser crystallization to convert amorphous silicon film into polysilicon, thereby increasing the electron mobility from 0.5 to 50-100 cm2/Vs to meet the requirements of OLED current drive. . After years of commercial mass production, the technology has superior performance and good work stability. At the same time, in the mass production of these years, the yield rate has been greatly improved, reaching about 90%, greatly reducing the product. cost. It can be seen from the above LTPS process flow that the main difference between it and the amorphous silicon technology is that the laser crystallization process and the ion implantation process are added, the other processing processes are basically the same, and the equipment has similarities with the amorphous silicon production. In addition, there are many kinds of crystallization technology. At present, ELA is the most commonly used small size. Other crystallization technologies include: SLS, YLA, etc. Some companies are also using other technologies to develop TFT substrates for AMOLEDs, such as metal induction. Crystallization technology, there are corresponding samples on display, but the main problem of this technology is that metal will lead to voltage breakdown between layers, leakage current is large, device stability can not be guaranteed (because AMOLED devices are particularly thin, each layer It is an important issue to ensure the cleanliness of the layer during processing and prevent voltage breakdown. The main defects of LTPS technology are as follows: â— The production process is more complicated, and the number of Masks used is 6-9, and the initial equipment input cost is high. â— Due to the limitation of laser crystallization process, large size is difficult. The largest production line is G4.5. â— Laser crystallization causes Mura to be severe, and it is used on TV panels, which causes visual defects. (3) Amorphous silicon technology (a-Si TFT) The most successful application of amorphous silicon technology is in the liquid crystal production process. Currently, most LCD manufacturers use a-Si technology except for a few LTPS technologies. The a-Si technology has high maturity in the liquid crystal field, and its device structure is simple. Generally, it is 1T1C (1 TFT thin film transistor circuit, 1 storage capacitor), and the number of Masks used in manufacturing is 4-5. At present, there are also manufacturers studying. 3Mask process. In addition, the a-Si technology is used for the production of AMOLED, and the equipment can completely use the original equipment processed by the current liquid crystal TFT, and the initial input cost is low. Furthermore, the large-scale realization of amorphous silicon technology has been fully realized, and currently it has achieved more than 100 inches in the field of LCD. Although a-Si technology is the mainstream in the LCD field, OLED devices are current-driven, and the low electron mobility of a-Si devices cannot meet this requirement, although some companies (such as IGNIS in Canada) design ICs. Some improvements have been made, but it is still not possible to solve the problem fundamentally. The main technical bottleneck of LTPS technology is the crystallization process, while the a-Si technology has no technical problems in the manufacturing process, but the design of the matching IC is very high, and the current IC manufacturers are mainly LTPS, a-Si The investment in IC development is small, so if a-Si technology is used for production, the source of IC is a serious bottleneck and a constraint, and the performance of the device will be greatly reduced. Wonke Electric CO.,Ltd. , https://www.wkdq-electric.com