Many of the new generation of color screen mobile phones support 65536 color display, and some even support 160,000 color display, then the high contrast of TFT, the advantages of rich colors are very important.
TFT technology is a large-scale semiconductor all-integrated circuit manufacturing technology developed in the 1990s using new materials and new processes, and is the basis for liquid crystal (LC), inorganic and organic thin film electroluminescent (EL and OEL) flat panel displays.
TFT is on a non-monocrystalline chip such as a glass or plastic substrate (of course, it can also be on a wafer) by sputtering, chemical deposition process to form a variety of membranes necessary for the manufacture of circuits, through the processing of membranes to produce large-scale semiconductor integrated circuits (LSIC).
The use of non-monocrystalline substrates can greatly reduce costs, which is an extension of traditional large-scale integrated circuits to large area, multi-function and low cost.
Manufacturing a TFT that controls the performance of a cell (LC or OLED) switch on a large area of glass or plastic substrate is more technically difficult than manufacturing a large-scale IC on silicon wafer.
The requirements for the production environment (purification degree is 100 grades), the requirements for the purity of raw materials (the purity of electronic special gas is 99.999985%), the requirements for production equipment and production technology are more than the large-scale integration of semiconductors, and it is the top technology of modern large-scale production. Its main features are:
(1) Large area: In the early 1990s, the first generation of large-area glass substrate (300mm×400mm) TFT-LCD production line was put into operation, and by the first half of 2000, the area of glass substrate had been expanded to 680mm×880mm), and the glass substrate of 950mm × 1200mm would also be put into operation. In principle, there is no limit to the area.
(2) High integration: The resolution of the 1.3-inch TFT chip for liquid crystal projection is XGA containing million pixels. The 16.1-inch TFT array amorphous silicon with a resolution of SXGA (1280×1024) has a film thickness of only 50nm, and the tab ON GLASS and SYSTEM ON GLASS technologies, the integration of their ICs, the requirements for equipment and supply technology, and the technical difficulty are more than those of traditional LSI.
(3) Powerful: TFT was the first to improve the light valve characteristics of liquid crystal as a matrix site selection circuit. For high-resolution displays, precise control of objects is achieved through voltage regulation in the 0-6V range (typically 0.2 to 4V), making it possible for LCDs to achieve high-quality high-resolution displays. TFT-LCD is the first flat panel display in human history to surpass CRT in display quality. And people are beginning to integrate driver ICs into glass substrates, and the entire TFT will be more powerful, which is unmatched by traditional large-scale semiconductor integrated circuits.
(4) Low cost: Glass substrates and plastic substrates fundamentally solve the cost problem of large-scale semiconductor integrated circuits, and open up a broad application space for the application of large-scale semiconductor integrated circuits.
(5) Flexible process: In addition to the use of sputtering, CVD (chemical vapor deposition) MCVD (molecular chemical vapor deposition) and other traditional processes such as film formation, laser annealing technology has also begun to be applied, which can make amorphous films, polycrystalline films, and can also manufacture single crystal films. Not only silicon films can be made, but other II.-VI and III.-V. semiconductor films can also be made.
(6) A wide range of applications, TFT technology-based liquid crystal flat panel display is the pillar industry of the information society, but also technology can be applied to the rapid growth of thin-film transistor organic electroluminescent (TFT-OLED) flat panel display is also growing rapidly.