TFT-LCD Manufacturing Process

- Jun 28, 2018 -


The tft-lcd manufacturing process includes the following steps: forming a tft array on a TFT substrate; forming a color filter pattern and an ito conductive layer on a color filter substrate; forming a liquid crystal cell with two substrates; mounting peripheral circuits, and assembling the backlight Source module assembly. 1. Processes for forming tft arrays on tft substrates Industrialized tft types include: amorphous silicon tft (a-si tft), polysilicon tft (p-si tft), single crystal silicon tft (c-si tft ) Several kinds. The most used is still a-si tft. The a-si tft fabrication process involves sputtering a gate material film on a borosilicate glass substrate, forming a gate wiring pattern after mask exposure, development, and dry etching. General mask exposure stepper. The second step is continuous film formation using the pecvd method to form a sinx film, an undoped a-si film, and a phosphorus-doped n+a-si film. Then mask exposure and dry etching are performed to form the a-si pattern of the tft portion. In the third step, a transparent electrode (ITO film) is formed by a sputter film forming method, and the display electrode pattern is formed by mask exposure and wet etching. In the fourth step, the formation of the contact hole pattern of the gate end insulating film is performed using mask exposure and dry etching. The fifth step is to sputter the film of Al etc., exposing and etching with a mask to form the source, drain and signal line patterns of tft. Finally, a protective insulating film is formed by the pecvd method, and then the insulating film is etched by mask exposure and dry etching. (The protective film is used for protecting the gate and the signal line electrode end and the display electrode). At this point, the entire process is completed. The tft array process is the key to the manufacturing process of tft-lcd, and it is also the most investment in equipment. The entire process requires very high purification conditions (eg class 10). 2. Process for Forming a Color Filter Pattern on a Color Filter (cf) Substrate The method for forming a colored portion of a color filter includes a dye method, a pigment dispersion method, a printing method, an electrolytic deposition method, and an ink-jet method. At present, pigment dispersion is the main method. The first step of the pigment dispersion method is to disperse fine particles of fine particles (average particle size less than 0.1 μm) (r, g, and b colors) in a transparent photosensitive resin. Then, they were sequentially coated, exposed and developed to form an r. g.b tricolor pattern. Photolithography is used in manufacturing, and the devices used are mainly coating, exposure, and development devices. In order to prevent light leakage, a black matrix (bm) is generally added at the rgb junction. In the past, a single-layered metal chromium film was formed by a sputtering method. Now, a resin type bm in which a bm film or a resin-mixed carbon of a mixed type of metal chromium and chromium oxide is used is also used. In addition, it is also necessary to make a protective film on the bm and to form an it0 electrode, since the substrate with a color filter is a front substrate as a liquid crystal panel and a rear substrate with a tft together constitute a liquid crystal cell. Therefore, attention must be paid to the positioning problem so that each unit of the color filter corresponds to each pixel of the TFT substrate. 3. Preparation process of the liquid crystal cell First, a polyimide film is coated on the surface of the upper and lower substrates, respectively, and through an abrasion process, an alignment film that can induce molecules to be arranged according to requirements is formed. Afterwards, the sealant material is placed around the tft array substrate, and the liner is sprayed on the substrate. At the same time, a silver paste was applied to the end of the transparent electrode of the cf substrate. Then, the two substrates are aligned and aligned so that the cf pattern is aligned with the tft pixel pattern, and the sealing material is cured by heat treatment. When printing the sealing material, it is necessary to leave the injection port so as to vacuum-fill the liquid crystal. In recent years, with the advancement of technology and the continuous increase in the size of substrates, there has also been a great improvement in the manufacturing process of cartridges. The most representative one is the change in the mode of crystal irrigation, from the original post-filling to the odf. The method, that is, the irrigation crystal and the box are synchronized. In addition, the padding method is no longer the traditional method of spraying, but directly on the array with photolithography. 4. Module Assembly Process of Peripheral Circuit, Assembled Backlight, etc. After the manufacturing process of the liquid crystal cell is completed, the peripheral drive circuit needs to be mounted on the panel, and then the polarizer is attached on the surface of the two substrates. If it is a transmissive lcd. also install the backlight.

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