利用鈍化層與雷射退火改善由大氣電漿輔助化學氣相沉積製備氧化鉿/氧化鋁/銦鎵鋅氧薄膜電晶體之電性研究

Abstract

近幾年來，銦鎵鋅氧薄膜電晶體被廣泛的研究，主要由於其良好的均勻性及高的遷移率具有很大的發展性，並於大尺寸主動矩陣平面顯示器以及主動矩陣有機發光二極體應用上，都有相關的研究。而隨著半導體技術的發展，尺寸越做越小的情況下，薄膜電晶體的漏電問題也就越來越被重視，通常解決此漏電問題的方法，就是把高介電材料應用在閘極的介電層裡，因為高介電材料的介電系數比一般材料高，所以可以讓閘極的介電層在薄一點，也不會造成太大的漏電問題。 而在對銦鎵鋅氧的製程方式，我們是藉由新穎式大氣壓電漿輔助化學氣相沉積開發銦鎵鋅氧化物薄膜電晶體，利用較無環境危害水溶液式硝酸金屬鹽類的前驅物，可直接在大氣環境下沉積，而不是在真空大氣壓下沉積，此大氣電漿技術具有、低溫、低成本、適合大面積化等競爭優勢，可期望於未來商業化應用。 本論文旨是要探討在不同爐管退火的溫度下，薄膜電晶體的特性比較，並且討論出比較好的特性溫度之後，再對其爐管退火的溫度下，進行其他的後續處理與比較。從實驗中，我們可以知道500°C的退火對於雙層氧化鋁跟氧化鉿所製作出來的薄膜電晶體特性是比較好的，所以我們選擇500°C做後續的處理。首先我們先利用雷射退火的方式，來比較有退火跟沒有退火的差異性，從我們的研究中可以發現，有雷射退火的薄膜電晶體，電流跟遷移率會比沒有雷射退火的薄膜電晶體來的高，整體特性可以說都有明顯的改善。再來的後續處理便是在銦鎵鋅氧層的上方，多沉積一層光阻當作保護層，讓銦鎵鋅氧層比較不會接觸到大氣中的氧氣和水分子，不會造成臨界電壓太多的偏移，通常我們都會跟沒有沉積上保護層的薄膜電晶體比較其臨界電壓的偏移大小，在此篇論文中，我們會各別加熱50°C、80°C、100°C，並且都各加熱3000秒，來觀察有保護層跟沒保護層的臨界電壓哪一個偏移比較多，而從我們的實驗可以發現到，有保護層的薄膜電晶體臨界電壓的偏移確實會比沒有保護層的薄膜電晶體來的小，因此，我們可以知道這兩種後續處理，都可以有效提高薄膜電晶體的特性，還有其穩定性。

Recently, amorphous indium-gallium-zinc oxide thin film transistors are become attractive for use as driving devices in large scale active matrix organic light emitting diode applications and as switching devices in active matrix liquid crystal displays because of the area uniformity and the filed effect mobility. When the fabrication technology become better, the TFT device size become smaller. When the device size become smaller, the leakage current problem become more important. To solve this problem, we use high-k material as gate dielectric layer in the TFT device. Because of the high dielectric constant, the TFT device size can be smaller than before. And IGZO film in new process technology is developed. Novel atmospheric pressure plasma enhanced chemical vapor deposition oxide (AP-PECVD) is proposed to fabricate IGZO film. Also, water-based metal salt solution, which is an eco-friendly precursor, is adopted, and the thin film can be deposited in atmospheric environment. The non-vacuum AP-PECVD offers several competitive advantages, such as low temperature process, low cost and suitable for large area application. It is expected for commercial applications in the future. In this letter, fabricate the IGZO TFT device as the gate dielectric layer annealing at different temperature by furnace. And we compare the performance of the TFT device. Then we choice the best performance of the TFT device to use laser annealing and passivation layer that compares the TFT device without any treatment. Frist, we discuss the TFT device with laser annealing treatment, from our experiment, we can realize the on current and filed effect mobility is better than the TFT device without laser annealing treatment. Second, the photoresist is deposited on the top of the IGZO film, let IGZO film no reaction with oxygen and water molecules in surroundings. Usually, we compare the shift of threshold voltage of TFT device with passivation layer and no passivation layer. In this letter, the TFT device is heating from 0s to 3000s at 50°C, 80°C, and 100°C, respectively. According to this experiment, we know the shift of threshold voltage of the TFT device with passivation layer is smaller than the TFT device without passivation layer. Finally, we can realize the performance and the stability of the TFT device in these treatment is better than the TFT device without any treatment.