氧化鋅薄膜電晶體製程研究

本研究對氧化鋅薄膜電晶體在退火溫度300°C ~500°C及退火環境空氣及氮氣中完成之氧化鋅薄膜特性及薄膜電晶體效能差異做深入的探討。實驗採用sol-gel法製作氧化鋅薄膜電晶體，氧化鋅屬於無機材料，故可得到較有機材料所製作成之薄膜電晶體更高的載子遷移率。氧化鋅薄膜之沉積方式有很多，一般都是以濺鍍方式成長之氧化鋅薄膜可有較佳之品質，但其缺點為難以實現大面積塗佈及高成本。故在本研究中採用氧化鋅溶液來沉積通道層薄膜，以降低製程成本。首先調配氧化鋅溶液，前驅物以醋酸鋅融入去離子水，即可得到高溶解性之氧化鋅水溶液。使用金作為閘極、源極與汲極，以形成較好之金半接面。為了可以符合薄膜電晶體液晶顯示器(TFT-LCD)的製程，又根據熱重分析(TGA)的結果，將退火溫度設定在300°C ~500°C。接著以XRD及SEM分析氧化鋅薄膜，薄膜晶格強度及晶粒大小隨著退火溫度升高而增加，且在氮氣中退火可得到比在空氣中退火更高之晶格強度及較大的晶粒。由片電阻值可看出阻值是隨著退火溫度增加而減少。最後採用黃光微影製程來實現氧化鋅薄膜電晶體，在退火溫度300°C ~400°C之薄膜電晶體實現臨界電壓≈2V之低驅動電壓。在氮氣中退火400°C之氧化鋅薄膜電晶體之載子遷移率達到3.71cm2/Vs，在空氣中退火500°C之氧化鋅薄膜電晶體之載子遷移率達到7.77cm2/Vs，開關電流比>105，次臨界擺幅為0.78V/dec。在氮氣中退火之氧化鋅薄膜有著較佳之結晶性以及較大的晶粒，所製作出之薄膜電晶體也有著較佳的效能表現。本研究以溶液法製作出高效能、低功耗且環保之氧化鋅薄膜電晶體。

關鍵字

氧化鋅；薄膜電晶體；薄膜性質

並列摘要

The effect of ZnO thin film transistors annealed in different ambiences is presented. In this research, solution-process ZnO thin film transistor has been demonstrated. Zinc oxide is an inorganic material. Therefore, the thin film transistor fabricated by ZnO can obtain higher mobility than that fabricated by organic material. There are many methods which can deposit ZnO thin film. Generally speaking, ZnO thin film deposited by RF sputtering can get higher quality, yet the flaws of sputtering are high cost and difficult to implement large area coating, so solution process ZnO is chosen to be channel material to cut down the cost. First of all, the ZnO solution is synthesized. The zinc acetate dihydrate is dissolved in deionized water directly. Not only does cut down the cost, but also avoid employing some extremely hazardous solvent and stabilizer, such as 2-methoxyethanol and monoethanolamine to make whole process more eco-friendly. According to the result of TGA, the annealing temperatures are set at 300°C ~500°C. The properties of ZnO thin film under different annealing temperature as well as that under different annealing ambience would be discussed. Afterward, the ZnO thin film would be analyzed via SEM, XRD, four point probe, spectrum to comprehend more about ZnO thin film. In the end, the ZnO thin film transistor would be realized by photolithography. Annealing temperatures are in the range of 300 °C~500 °C, and annealing ambiences of both air and N2 are discussed. Threshold voltage form -0.84 V~2.4 V shows extremely low power consume. ZnO thin film transistors processed at 500 °C in air exhibits high performance, mobility of 7.7 cm2/Vs, and Ion/off ratio of 105. The ZnO thin films annealed in N2 with better crystallity and grain size are observed. In this research, high performace, low operating-voltage thin film transistors were demonstrated.

並列關鍵字

Zinc oxide ； Thin film transistor ； Solution process ； Thin film property ； Electrical property

參考文獻

[1] U . O zgur, “A comprehensive review of ZnO materials and devices,” J. Appl. Phys, vol. 98, 041301, 2005.

[2] Zhiyong Fan and Jia G. Lu, “Zinc Oxide Nanostructures: Synthesis and Properties,” Journal of Nanoscience and Nanotechnology, vol 5, pp. 1561-1573, 2005

[3] Zhong Lin Wang, “Zinc oxide nanostructures: growth, properties and applications,” J. Phys.: Condens. Matter, vol. 16, pp. 829–858, 2004

[4] Tao Pengcheng, Feng Qiuju, and Jiang Junyan, “Electroluminescence from ZnO nanowires homojunction LED grown on Si substrate by simple chemical vapor deposition,” CHEMICAL PHYSICS LETTERS, vol. 522, pp. 92-95, 2012.

[6] Y. Ryu and T.S. Lee, “Next generation of oxide photonic devices: ZnO- based ultraviolet light emitting diodes,” Appl. Phys. Lett., vol. 88, pp. 241108, 2006.

國際替代計量

氧化鋅薄膜電晶體製程研究

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