| Summary: | 碩士 === 國立臺灣科技大學 === 電子工程系 === 106 === Amorphous oxide semiconductor is considered to be the most competitive TFT material for last decade. It has several advantages such as great uniformity for large size display, low fabrication temperature and low production cost. In order to pursue greater metal oxide TFT performance and stability, there are many ways can improve such as fluorine-doped, nitrogen-doped and hydrogen-doped. Among all those doping material, the effects of fluorine incorporation in a-IGZO have not been studied complete. Therefore, we will focus on the electrical and stability of fluorinated amorphous InGaZnO-TFT by CF4 plasma treatment.
To begin with, we fabricated IGZO based TFT whose dielectric layer was SiO2 and use CF4 plasma to dope fluorine into IGZO. Through the SIMS depth profile, we discovered that fluorine atoms have diffused towards the a-IGZO/SiO2 interface. In addition, the FT-IR spectrum shows that the relatively content of CF2 and CF3 molecules depend on the plasma power. Next, high-k material HfO2 is selected as the gate insulator. Consequently, both high saturation carrier mobility and small S.S can simultaneously be obtained by the sample with CF4 plasma treatment. Moreover, this sample can operate in enhance mode and continuously positive gate bias with a small Vth shift. Overall, we want to try the best thickness of HfO2 layer with CF4 plasma treatment to achieve superior properties in the future.
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