TFT-LCD manufacturing process, detailed TFT-LCD manufacturing process

From the comparison between the TFT provided by Xingyuhe’s technical staff and other LCDs, we can see that TFT-LCD has many advantages (TFT-LCD characteristics). Then, what manufacturing process does TFT-LCD use to play its role in display? Regarding the huge advantages of the screen, this article will introduce the manufacturing process of TFT-LCD in detail. The manufacturing process of TFT-LCD has the following parts: forming a TFT array on a TFT substrate; forming a color filter pattern and an ITO conductive layer on a color filter substrate; using two substrates to form a liquid crystal cell; installing peripheral circuits and assembling a backlight Source and other modules are assembled. 1. The process of forming a TFT array on a TFT substrate. The types of TFTs that have been industrialized include: amorphous silicon TFT (a-SiTFT), polysilicon TFT (p-SiTFT), and monocrystalline silicon TFT (c-SiTFT). . At present, the most used is still a-SiTFT. The manufacturing process of a-SiTFT is to sputter the gate material film on the borosilicate glass substrate, and form the gate wiring pattern after mask exposure, development, and dry etching. Stepper exposure machine is generally used for mask exposure. The second step is to use PECVD method for continuous film formation to form SiNx film, non-doped a-Si film, and phosphorus-doped n+a-Si film. Then perform mask exposure and dry etching to form the a-Si pattern of the TFT part. The third step is to use sputtering to form a transparent electrode (ITO film), then mask exposure and wet etching to form a display electrode pattern. The fourth step is to form the contact hole pattern of the insulating film at the gate end using mask exposure and dry etching. The fifth step is to sputter the AL, etc. to form a film, expose and etch with a mask to form the source, drain and signal line patterns of the TFT. Finally, a protective insulating film is formed by the PECVD method, and then the insulating film is etched and formed by mask exposure and dry etching (the protective film is used to protect the gate, the end of the signal line electrode and the display electrode). At this point, the entire process is completed. The TFT array process is the key to the TFT-LCD manufacturing process, and it is also the part with the most equipment investment. The entire process is required to be carried out under very high purification conditions (for example, level 10). 2. The process of forming color filter patterns on the color filter (CF) substrate. The methods for forming the colored part of the color filter include dye method, pigment dispersion method, printing method, electrolytic deposition method, and inkjet method. At present, the pigment dispersion method is the main method. The first step of the pigment dispersion method is to disperse fine pigments with uniform particles (average particle size less than 0.1 μm) (three colors of R, G, and B) in a transparent photosensitive resin. Then they are applied, exposed, and developed in sequence to form R.G.B three-color patterns in sequence. Photoetching technology is used in manufacturing, and the equipment used is mainly coating, exposure, and development equipment. In order to prevent light leakage, a black matrix (BM) is generally added at the junction of the RGB three colors. In the past, sputtering was often used to form a single-layer metal chromium film, but now there are also metal chromium and chromium oxide composite type BM films or resin mixed carbon resin type BM. In addition, it is necessary to make a protective film on the BM and form the IT0 electrode, because the substrate with color filter is used as the front substrate of the mobile LCDscreen screen and the rear substrate with TFT together to form the liquid crystal cell. Therefore, we must pay attention to the positioning problem, so that each unit of the color filter corresponds to each pixel of the TFT substrate. 3. The preparation process of the liquid crystal cell. The first is to coat polyimide film on the surface of the upper and lower substrates respectively and through the rubbing process to form an alignment film that can induce the molecules to be arranged as required. After that, a sealant material is placed around the TFT array substrate, and gaskets are sprayed on the substrate. At the same time, silver paste is applied to the end of the transparent electrode of the CF substrate. Then the two substrates are aligned and glued so that the CF pattern and the TFT pixel pattern are aligned, and the sealing material is cured by heat treatment. When printing the sealing material, it is necessary to leave the injection port so that the mobile LCDscreen can be filled with a vacuum. In recent years, with technological progress and the continuous increase of substrate size, there have also been great improvements in the manufacturing process of the box. The more representative one is the change in the method of filling the crystal, which is changed from the original filling after the box is formed to ODF Method, that is, the crystal filling and box forming are performed simultaneously. In addition, the padding method no longer uses the traditional spraying method, but is directly made on the array by photolithography. 4. Module assembly process for peripheral circuits, assembling the backlight, etc. After the mobile LCDscreen cell manufacturing process is completed, the peripheral driving circuit needs to be installed on the panel, and then polarizers are pasted on the surfaces of the two substrates. If it is a transmissive LCD. Also install a backlight. Materials and processes are the two main factors that affect product performance. TFT-LCD undergoes the above four main manufacturing processes, and a large number of complicated manufacturing processes form the final product we see.

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