以溶液製程製作鋯銦鋅氧化物半導體薄膜電晶體

Abstract

本研究選用鋯銦鋅氧化物(ZrInZnO)為薄膜電晶體的主動層，不同於以往使用濺鍍的方式，而是以溶液製程的方式旋轉塗佈在矽-二氧化矽基板上當做主動層，並以鋁當作電極材料，研究其元件特性。當Zr的含量增加時，關閉電流也會隨之下降。當ZrInZnO的比例為Zr: In: Zn = 0.1: 5: 5時，場效遷動率為3.8cm2/Vs，開關電流比大約為107，截止電壓為0.44V，次臨界擺幅為0.42 V/dec。在壓力測試中，ZIZO在10伏特的偏壓下一段時間後，截止電壓的漂移亦能保持穩定。 ZIZO薄膜結晶為非晶型，Zr原子能有效地控制氧空缺和提供自由電子。XPS證明當Zr含量增加時，氧原子1s的鍵結峰值減少，此即為氧空缺數量減少的證據。除此之外，我們還發現添加氫氧化鈉(NaOH)能使ZIZO的薄膜更加穩定並且加速ZIZO的結晶化反應，減少元件的製作時間。

Solution-processed ZrInZnO (ZIZO) semiconductors have been fabricated as the channel material for thin film transistors (TFTs). As the amount of Zr content increased, the off current decreased. The ZIZO TFTs fabrication with the ratio of Zr: In: Zn = 0.1: 5: 5 exhibited a field effect mobility of 3.8 cm2/Vs, an on-off ratio of ~107, a threshold voltage (Vth) of 0.44 V and the subthreshold swing of 0.42 V/dec. The threshold voltage also became stable under the bias stress. We found that the ZIZO thin film was amorphous. However, when pre-annealing temperature increased, the degree of micro-crystallization was improved. We interred that the Zr effectively controlled the oxygen vacancies and supplied the concentration of free electron. X-ray photoelectron spectroscopy verified that the oxygen 1s peak decreased with the Zr increasing content. Therefore, it proved that oxygen vacancies decreased with adding the Zr. In addition, we found that adding NaOH could make the ZIZO thin film more stable and accelerate the chemical sol-gel reaction. Overall the device performance is almost comparable with that of the device made by conventional cosputtering methods.