於玻璃基板與塑膠基板上製作高效能氧化鋅薄膜電晶體

Abstract

本論文製作於玻璃基板與塑膠基板上之氧化鋅薄膜電晶體的特性。 在實現薄膜電晶體元件之前，本文首先探討氧化鋅缺限對氧化鋅薄膜導電特性的影響，藉由濺鍍沉積氧化鋅薄膜時控制Ar和O2的比例，以及利用氧電漿對氧化鋅薄膜表面進行處理，以獲得最佳製備氧化鋅薄膜的成長環境。根據此最佳化條件，本研究在玻璃基板上製作出高效能增強型氧化鋅薄膜電晶體，在Vds=10-20，Vgs=5V的偏壓下，操作電流可高達1mA，開關電流比可達3x10*6，是目前氧化鋅薄膜電晶體的研究工作中，效能表現最好之一。 本文進一步探討製作於塑膠板上之氧化鋅薄膜電晶體的特性。採用兩步驟的黃光製程，以防止塑膠基板在化學溶劑中產生變形；而受限於塑膠基板的玻璃轉換溫度，所有薄膜均在室溫下濺鍍成長，氧化鋅的成長條件是利用玻璃基板上的最佳結果。另外，採用金屬鈦作為汲極和源極，以改善接觸電阻。塑膠基板上之氧化鋅薄膜電晶體的電特性曲線和可見光穿透率均本文中亦有論及。

This thesis focuses on two aspects of ZnO thin film transistors, the ZnO-TFTs fabricated on glass substrates and the flexible ZnO-TFTs fabricated on polymer substrates. The first part demonstrates a high-performance enhancement-mode ZnO TFT on a glass substrate. Before realizing the TFT device, the characteristics of ZnO thin films are examined to find out the optimal deposition conditions. The ZnO thin film is deposited by RF magnetron sputtering with the presence of O2 at low deposition rate and low temperature. The IDS of the ZnO-TFT on glass substrates is as high as 1 mA when biased at the saturation region VDS = 10-20 V and VGS = 5 V without any post thermal anneal. The Ion/Ioff ratio is . We believe the results are among the best ZnO TFTs ever obtained. The second part focuses on the flexible ZnO-TFT on PET (polyethylene terephthalate) substrates. All the patterns are defined by standard photolithography with only two steps in order to reduce the distortion of PET substrates. The ZnO thin film is deposited by RF magnetron sputtering at low temperature in presence of O2. The gas ratio of Ar to O2 is based on the optimal conditions obtained in the case of the ZnO-TFT on glass substrates. Titanium is employed in substitution for ITO as the source and the drain layers to improve the electrical performance. The IDS - VDS curves along with optical transmission of the whole structure are presented.