- 學位論文
整合氮化鋁薄膜緩衝層及表面鈍化層技術於製作T型閘極高電子遷移率電晶體及其高頻分析
Integrating Aluminum Nitride Film Buffer Layer and Surface Passivation Layer Technology in the Production of T-gate High Electron Mobility Transistors and High Frequency Analysis
摘要
氮化鎵被稱為第三代半導體材料，以其為材料的氮化鋁鎵/氮化鎵高電子遷移率電晶體，因具有二維電子氣以及寬能隙的特性，故在高頻高功率元件上具有極大的發展及應用空間。 本論文使用氮化鋁緩衝層磊晶之基板，在其磊晶片上製備高電子遷移率電晶體，元件製程中結合了 T 型閘極技術和鈍化層生長技術，並將所製備的元件進行高頻量測分析。 在論文第一部分，我們以信號流圖的觀點，重新推導了高頻元件所需用到的基礎微波理論，並且用此方法構建出了小訊號模型的精準 S 參數公式，用以擬合小訊號模型中各個電子元件的參數。 在論文第二部分，我們以電子束微影系統曝光三層光阻結構，並控制顯影的時間，在蒸鍍金屬後，成功製作出閘極線寬為 300 奈米、閘極頭寬為 700-900 奈米之T 型閘極。 在論文第三部分，我們分析了元件的直流特性，並藉由開路及短路襯墊進行去嵌化，將元件的本質參數萃取出來。證明了我們所設計的開路和短路襯墊符合開路短路襯墊去嵌化的條件。經過數據分析後，我們的 HEMT 元件在閘極電壓為-3.5 伏特，汲極電壓為 6 伏特時有截止頻率𝑓𝑡 = 10𝐺𝐻𝑧, 𝑓𝑚𝑎𝑥 = 18𝐺𝐻𝑧。
並列摘要
GaN is a prevalent third generation semiconductor material because of its 2DEG and broad energy gap, Therefore, high electron mobility transistors (HEMTs) based on GaN can be used to design high frequency or high power devices. In this work, we fabricate HEMTs based on the structure that adopting AlN as an epitaxy buffer. The T gate and the epitaxy buffer technique are adopted in this work. In addition, we also analyze the devices in the high frequency domain. This thesis is composed of three parts. First, we reorganize the micro wave theory with the viewpoint of the signal flow graph. Then, we use it to construct the small signal model and derive the S parameter formula. After that, we can fit a model and get all the parameters in the devices. Second, we design a three layers photoresist structure and use E beam to exposure. We control the exposure time and figure out the optimal. After Evaporating, we fabricate a T gate structure with 300 nm gate length and approximately 800 nm gate head length. Last, the DC property of our devices is analyzed. We adopt open short pad de embedding to extract the intrinsic parameters of devices.Our HEMTs provide a 10 GHz current gain cut off frequency when the gate voltage is 3.5V, and the drain voltage is 6 V. The maximum oscillation frequency is 18 GHz.