TFT technology was developed in the 1990s. It adopts new materials and new processes for large-scale semiconductor full integrated circuit manufacturing technology. It is a liquid crystal (LC), inorganic and organic thin film electroluminescence (EL and OEL) flat panel display. basis. TFTs are formed on glass or plastic substrates and other non-single wafers (of course, they can also be on wafers) by sputtering and chemical deposition processes to form various films necessary for manufacturing circuits, and large-scale semiconductor integrated circuits (LSIC) are produced by processing the films . The use of non-single crystal substrates can greatly reduce costs, which is the extension of traditional large-scale integrated circuits to large areas, multi-functions, and low costs. Manufacturing TFTs that control the switching performance of pixel (LC or OLED) on large-area glass or plastic substrates is more difficult than manufacturing large-scale ICs on silicon wafers. The requirements for the production environment (purification degree is 100), 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, is the top of modern large-scale production technology. Its main features are:

large area

The first generation of large-area glass substrate (300mm×400mm) TFT-LCD production line was put into operation in the early 1990s. By the first half of 2000, the area of the glass substrate has been expanded to 680mm×880mm), and the more recent 950mm×1200mm glass substrate will also be put into operation run. In principle, there is no area limit.

High integration

The 1.3-inch TFT chip used for liquid crystal projection has a resolution of XGA containing millions of pixels. The thickness of 16.1 inch TFT array amorphous silicon with a resolution of SXGA (1280×1024) is only 50nm, and TAB ON GLASS and SYSTEM ON GLASS technologies, the integration of IC, the requirements for equipment and supply technology, and the technical difficulty Are more than traditional LSI.

Powerful

TFT used as a matrix addressing circuit earlier to improve the light valve characteristics of liquid crystal. For high-resolution displays, through the voltage adjustment in the range of 0-6V (its typical value is 0.2 to 4V), the precise control of the object element is achieved, thereby making it possible for the LCD to achieve high-quality high-resolution display. TFT-LCD is the first flat panel display in human history that exceeds CRT in display quality. Now people start to integrate the driver IC on the glass substrate, and the function of the entire TFT will be more powerful, which is unmatched by traditional large-scale semiconductor integrated circuits.

low cost

The glass substrate and the plastic substrate 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.

Flexible process

In addition to sputtering, CVD (Chemical Vapor Deposition) MCVD (Molecular Chemical Vapor Deposition) and other traditional processes for film formation, laser annealing technology has also begun to be applied. It can produce amorphous films, polycrystalline films, and single crystal films. Not only can the silicon film be made, but also other II-VI and III-V semiconductor thin films can be made.