| Amorphous -silicon thin-film transistors liquid crystal displays(a-Si TFT-LCD) have become the key technology in high image quality displays as note PC and LCTV. The fabricate techniques of a-Si TFT-LCD have been ripped in abroad, and very backward in home, more backward in big size, ratio of fishing product and display characteristics. As our technology now, we lay particular emphasis on the design and fabrication of the high ratio of fishing product and high display characteristics of a-Si TFT-LCD. In the paper, the main content includes the fabrication of high optical and electric characteristics a-Si TFT function films, design and fabricate techniques of a-Si TFT-LCD of high ratio of fishing product and high display characteristics.In a-Si TFT-LCD, a-Si TFT work as a switch, complete respond to signal by quickly charge to pixel capacitances in a-Si TFT on state, and store signal by keep electricity of pixel capacitance in a-Si TFT off state. The basic characteristics of a-Si TFT is getting ride of the cross effect and highly keep electricity.An a-Si TFT is consist of many layers different material. In the paper, the ITO and Al/Cr film is deposited by sputtering, a-Si and SiNx film is deposited by PECVD. The electric mobility is improved by H treating the interface of a-Si/SiNx. The characteristics and deposit parameters of these films is in keep with the request that of the high image quality a-Si TFT-LCD. By the optical and electric characteristics of function films which have been deposited, the construct parameters of a-Si TFT which the pixel area is 166μm×166μm, aperture ratio is about 55％, W/L=7, Ion/Ioff is 106, storage capacitor is about 0.4PF is designed on 3in 320×240 array. In the construct, the different thickness two layers SiNx film, different thickness and low resistance Al/Cr two layer films, one layer a-Si film and common gate storage capacitor Cs is used. In the designed a-Si TFT construct, two layers low resistor gate lines may reduce the break wire defect and the effect of gate delay, two layers insulator help decrease the cross capacitance and short path defect, raise the strike through voltage, the common gate techniques of storage capacitor not only help increase aperture ratio, but also raise pixel voltage kept characteristics and reduce the impact of TFT parasitic capacitance.In a-Si TFT array fabrication, both self-alignment and traditional exposure techniques is used, i.e., TFT island is fabricated by self-alignment process, pixel electrode and source drain electrode is fabricated by traditional exposure process. It must have four times photo engrave in our design, less 2 times than traditional process, the ratio of fishing product may increase about 1/3 and get ride of the defect of the big parasitic capacitance in the simple self-alignment structure. ⅡThe designed a-Si TFT-LCD is simulated by SPICE.In etching techniques, after many times photo engraving and etching, find the best etching solution and etching conduction and the high selectivity. In SiNx , a-Si and n+a-Si films etch, HPO3, HNO3 and HF solution is used. HCl,HPO3, NHO3 and water solution is used for etching Al/Cr and ITO films. The characteristics parameters of fabricating a-Si TFT-LCD is measurement, the results conform to that of design.
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