利用閘極掘入方式製作增強型高截止電壓氮化鋁鎵/氮化鎵/氮化鋁鎵金屬-絕緣體-半導體高電子遷移率電晶體之研究

Abstract

氮化鋁鎵/氮化鎵/氮化鋁鎵增強型高電子遷移率電晶體近幾年來廣受注目，但由於目前之元件磊晶技術所製作的高電子遷移率電晶體之電流與電壓接仍偏低，尚無法做商業上之使用。而近年來之研究重點:金-氧-半場效電晶體雖擁有較高的起始電壓，但由於製程上尚未成熟，加上比起高電子遷移率電晶體其擁有較高的通道電阻，故仍未能通過工業使用標準。 本研究提出以閘極蝕刻之方式來製作增強型高起始電壓氮化鋁鎵/氮化鎵/氮化鋁鎵金屬-絕緣體-半導體高電子遷移率電晶體，並建立其標準化製程。此結構擁有比起金-氧-半場效電晶體較為簡易的製程，並擁有較低的電阻，同時此結構亦可達到較高之截止電壓。本實驗以蕭特基二極體做各種製程之參數測試，以找到對元件表現最好的使用條件，並成功建立金屬-絕緣體-半導體高電子遷移率電晶體之標準製程。此元件擁有2mA/mm的通道電流，0.8mS/mm之互導係數，並擁有超過200V之崩潰電壓，更達到了9V的高截止電壓。而此結構同時亦可用於製作截止型高電子遷移率電晶體，擁有280mA/mm之電流與75mS/mm之電導，同時亦可在高電壓下操作。

AlGaN/GaN/AlGaN enhancement-mode high electron mobility transistor (HEMT) is extensively studied in recent years. However, there is still no solution to fabricate a HEMT with high threshold voltage, which means that it will cause mis-operation in high voltage operation. For enhancement mode operation (E-mode), metal-oxide-semiconductor field effect transistor (MOS-FET), though it has higher threshold voltage, it is not commercialized due to the immature process techniques and higher on-resistance than HEMT. In this thesis, gate recess technique is used to fabricate E-mode AlGaN/GaN/AlGaN metal-insulator-semiconductor high electron mobility transistor (MIS-HEMT). This structure has simpler process and lower on-resistance in comparison with MOS-FET. Additionally, this structure can achieve very high threshold voltage to avoid the mis-operation of the device. Schottky diode was used for process parameter evaluation to find out the optimum process condition, and then the recessed E-mode MIS-HEMT standard process was established. The device demonstrated 2 mA/mm, 0.8 mS/mm, and more than 200V for channel current, transconductance, and three-terminal breakdown voltage, respectively. Furthermore, the device shows 9V threshold voltage. The structure can also be applied to conventional D-mode HEMT application with ID = 280mA/mm and Gm = 75 mS/mm. These characteristics indicate that the structure is promising for high voltage electronic applications.