Nanometer Silicon Thin Film Transistor Manufacture And Characteristic Research

In this paper, the basic structure, characteristics and application areas of a-Si:HTFT, poly-Si TFT and nc-Si:H TFT were discussed,the basic structure design of top gatenc-Si:H TFT was given,based on the working principles of MOSFET, the workingprinciples of nc-Si:H TFT was analyzed and given, combined with the nc-Si:H thin filmmicrostructure model, based on the a-Si:H TFT leakage current model, nc-Si:H TFTleakage current model was analyzed in this paper.In this paper,take the basic structuredesign of top gate nc-Si:H TFT as the foundation,established simulation model andanalysed the simulation of characteristics, study the influence of output characteristicsand transfer characteristics by the channel film thickness,the channel W/L. Based on thesimulation analysis, used the CMOS technology to design nc-Si:H TFT fabricationtechnology process, nc-Si:H thin films were made by LPCVD on SiO2layer were testedand superficial characteristics were studied by XRD, Raman spectra and AFM, achievedthe preparation of nc-Si:H thin films thicknesses were55nm,90nm and120nm, Thedeposition state of nc-Si:H thin films made on SiO2layer, with the increase of filmthicknesses, the crystallization peak <111>,<220> and <311> were enhanced; withhigh temperature vacuum annealing,the crystallization peak<111>,<220> and <311>were enhanced significantly.This paper adopted L-edit to design nc-Si:H TFT chip layout. The nc-Si:H thinfilms of55nm,90nm and120nm in thicknesses were directly deposited on n-type<100> Si wafer with high resistivity and SiO₂layer, respectively,we adopted CMOStechnology to complete nc-Si:H TFT fabrication and package. At room temperature, weadopted KEITHLEY4200semiconductor parameter test machine to test the electricalcharacteristics, and studied the influence of substrate type, channel film thickness, andchannel width-length ratio to TFT output and transfer characteristics.The experimentalresults show that, at room temperature, nc-Si:H TFT was made on SiO₂layer has switchcurrent ratio10⁶, open state current0.8×10^-4A, close state current0.5×10^-10A,threshold voltage17V, carriers mobility7.32cm²/V·s.