應用雙層高介電質材料氧化鋯/氧化鋁鑭於製備大氣 噴射式電漿沉積氧化銦鎵鋅薄膜電晶體之特性研究

Abstract

近年來氧化銦鎵鋅薄膜電晶體越來越重要。因為氧化銦鎵鋅材料已經因其具有高電子遷移率、高開關電流比、低次臨界擺幅而被廣泛運用於下一世代平面顯示器之背板上，例如主動式矩陣液晶顯示器及主動式矩陣有機發光顯示器。由噴射式大氣電漿沉積之氧化銦鎵鋅薄膜具有許多優點例如低製造成本、在大面積運用上具有高穩定度、無需真空腔體以及其相關之抽氣系統。除此之外，厚膜二氧化矽作為閘極氧化層會大幅增加臨界電壓、操作電壓以及降低其電容密度。高介電質材料像是二氧化鉿及二氧化鋯已被指出具有極佳的特性運用在薄膜電晶體元件上，例如高崩潰電場強度、高介電質係數以及其和室溫下製程可相容。也有文獻指出噴射式大氣電漿沉積之氧化銦鎵鋅薄膜氧化鋁閘極介電質電晶體在電子遷移率、開關電流、次臨界擺幅以及臨界電壓上具有好的電性。在本論文之中，我們運用噴射式大氣電漿製造和研究鋁酸鑭/二氧化鋯/氧化銦鎵鋅薄膜電晶體。此電晶體具有場效電子遷移率8.45(平方公分/伏特-秒)、臨界電壓0.87伏、次臨界擺幅0.15(伏/十進位)和開關電流比1.6x107。我們元件具有極佳的電性。

Indium-gallium-zinc-oxide thin-film transistors (IGZO TFTs) have gathered importance in recent years. IGZO material have been widely used for backplanes of the next-generation flat-panel displays, such as active matrix liquid crystal displays (AMLCDs) and active matrix organic light emitting diode displays (AMOLEDs) due to their high field-effect mobility, large Ion/Ioff ratio, smaller subthreshold swing. IGZO films deposited by atmospheric pressure plasma jet (APPJ) has many advantages such as low cost and good suitability for large scale applications, since it does not need a vacuum chamber and associated pumping system. Moreover, the thick gate oxide (SiO2) layer seriously increases the threshold voltage, operation voltage, and low capacitance density. High-K materials of ZrO2 and HfO2 have investigated with their superior properties for advanced TFT devices, such as high breakdown field intensity (10~15 MV/cm), high dielectric constant (20~25), and the capability of room-temperature process. We also have reported that IGZO prepared by APPJ with a gate dielectric of Al2O3 exhibited good electrical performance on mobility, Ion/Ioff ratio, subthreshold swing and threshold voltage. In this thesis, we have fabricated and investigated LaAlO3/ZrO2/IGZO TFTs by atmospheric pressure plasma jet. The resulting transistor exhibits field-effect mobility of 8.45 cm2/V-s, a threshold voltage of 0.87 V, a subthreshold swing of 0.15 V/dec, and an Ion/Ioff ratio of 1.6x107. Our device demonstrated excellent electrical characteristics.