TFT liquid crystal display screen is characterized by good brightness, high contrast, strong hierarchy and bright color, but it also has the shortcomings of high power consumption and high cost. TFT liquid crystal technology accelerates the development of mobile phone color screen. Many of the new generation of color screen phones support 65536 color display, and some even support 160000 color display. At this time, the high contrast of tft and the advantage of rich color are very important.
Tft technology is developed in the 1990 's, and the technology of large-scale semiconductor integrated circuit with new material and new process is the base of liquid crystal (lc), inorganic and organic thin film electroluminescent (el and oel) flat panel display. The tft is a variety of films necessary for manufacturing a circuit by sputtering or a chemical deposition process on a non-single-crystal sheet such as a glass or plastic substrate (and, of course, on a wafer), and a large-scale semiconductor integrated circuit (sic) is fabricated by the processing of the film. The adoption of the non-single-crystal substrate can greatly reduce the cost, and is an extension of the traditional large-scale integrated circuit to the large-area, multi-functional and low-cost direction. Manufacturing a tft that controls the performance of an image element (lc or oled) on a large area of glass or plastic substrate is more difficult to manufacture a large-scale ic on a silicon wafer. The requirements for the production environment (the degree of purification is 100), the requirements for the purity of the raw materials (the purity of the electronic special gas is 99.999985%), the requirements for the production equipment and the production technology exceed the large-scale integration of the semiconductor, and are the top technology of the modern large-scale production.
The main characteristics are:
(1) large area: the first generation large-area glass substrate (300 mm-400mm) tft-lcd production line in the early 1990s is put into operation, and the area of the glass substrate has been expanded to 680 mm (880 mm) in the first half of 2000, and the glass substrate of 950 mm to 1200 mm will also be put into operation. In principle there is no limitation of area.
(2) High integration: the resolution of 1.3 inch tft chip for liquid crystal projection is that xga contains millions of pixels. The film thickness of 16.1 inch tft array amorphous silicon with resolution sxga (1280 × 1024) is only 50nm, as well as tab on glass and system on glass technology, the integration of ic and the requirement of equipment and supply technology are all more difficult than the traditional lsi..
(3) powerful function: tft first used as matrix location circuit to improve the optical valve characteristics of liquid crystal. For high resolution display, the accurate control of object element is realized by voltage regulation in the range of 0 ≤ 6 v (its typical value is 0.2 to 4 v), which makes it possible for lcd to realize high quality and high resolution display. Tft-lcd is the first flat panel display with display quality exceeding crt in human history. Moreover, people begin to integrate driving ic into glass substrate, and the function of the whole tft will be more powerful, which is incomparable to the traditional large-scale semiconductor integrated circuits.
(4) low cost: glass substrate and plastic substrate fundamentally solve the cost problem of large scale semiconductor integrated circuits, which opens up a broad application space for the application of large scale semiconductor integrated circuits.
(5) the process is flexible: in addition to the traditional process such as sputter, cvd (chemical vapor deposition () mcvd (molecular chemical vapor deposition), laser annealing technology has also begun to be applied, which can not only fabricate amorphous films, polycrystalline films, but also single crystal films. Not only silicon films can be made, but also other II-group and III-group semiconductor films can be fabricated.
(6) liquid crystal flat panel display (LCD) based on tft technology is the pillar industry of information society, and it can also be applied to thin film transistor organic electroluminescent (tft-oled) flat panel display which is growing rapidly. Other main features