本篇論文主要在研製準垂直型溝槽式氮化鎵金氧半場效電晶體於藍寶石基板。藉由高解析度X光電子能譜分析，可以發現經由感應式耦合電漿蝕刻後會使得Ga 2p3/2元素訊號的峰值位移，指出其材料表面遭受破壞，為了解決表面破壞的情形，本論文採取Digital Etch(D.E)的蝕刻方式進行表面處理，且探討晶面及D.E表面處理對元件特性的影響。
本論文採用不同表面處理方式，分別為：(a)浸泡鹽酸、BOE與硫酸，(b)在200oC環境下進行10次的D.E，(c)在200oC環境下進行20次的D.E，(d)在200oC環境下進行20次的D.E搭配浸泡酸液，及(e)在450oC環境下進行20 次的D.E搭配浸泡酸液。
由量測結果得知，即使經過不同條件的表面處理，蝕刻過後的溝槽表面仍存在許多的陷阱，必須使用脈衝模式及搭配UV光照射的量測方式，才可以得到合理的輸出特性，整體而言，元件在200oC環境下進行20次的D.E表面處理過後可得到最佳的元件特性，該臨界電壓為5.5 V、最大汲極電流密度達0.83 A/mm2，經計算後的場效遷移率僅有4.8 (cm2/V-s)。

In this study, quasi-vertical trench gate of the gallium nitride (GaN) MOSFETs were fabricated on sapphire substrate. From high-resolution X-ray photoelectron spectroscopy (HR-XPS) analysis, it was found that the Ga 2p3/2 peak was shifted by the etching of inductive coupling plasma, which indicates that the surface was damaged. In order to recover the surface properties, the treatment of digital etch (D.E) on the surface was carried out.
Five samples with quasi-vertical MOSFETs going through different surface treatments listed as the following were completed and compared: (a) soaking in hydrochloric acid, BOE and sulfuric acid. (b) 10 cycles of D.E at 200 °C (c) D.E for 20 cycles in a 200 °C environment. (d) 20 cycles of D.E at 200 °C with soaking in acids. (e) 20 cycles of D.E at 450 °C with soaking in acids.
From the measurements, it was discovered that even though the surface had been through different treatments, there might still exist a lot of traps on the etched trench surface. Pulse mode must be used in measurements together with UV light on in order to obtain reasonable output characteristics. Overall, the device treated with 20 cycles of digital etch at 200 ° C has the best device characteristics. With a threshold voltage (Vth) of 5.5 V and a maximum drain current density of 0.83 A/mm2, the calculated mobility is only 4.8 (cm2/V-s).

中文摘要 I
Abstract II
目錄 III
圖目錄 V
表目錄 VIII
第一章 序論 1
1.1 前言 1
1.2 研究動機與文獻回顧 3
1.3 研究方向簡介與論文架構 10
1.3.1 研究方向簡介 10
1.3.2 論文架構 10
第二章 材料介紹與實驗設計 11
2.1 氮化鎵材料介紹與基板選擇 11
2.2 試片磊晶結構 12
2.3 閘極氧化層 14
2.4 Digital Etch 14
2.5 元件設計 15
2.6 試片分類 18
第三章 光罩設計與元件製程 19
3.1 準垂直型溝槽式閘極金氧半場效電晶體製作流程 19
3.2 試片溶劑清潔 20
3.3 溝槽式閘極及對準記號蝕刻 (Mask 1) 20
3.4 基極溝槽蝕刻(Mask 2) 22
3.5 汲極深蝕刻(Mask 3) 24
3.6 表面處理與閘極氧化層 25
3.7 源極電極之製作 (Mask 4) 26
3.8 基極電極之製作 (Mask 5) 28
3.9 閘極金屬與源極襯墊金屬之製作 (Mask 6) 29
3.10 汲極電極之製作 (Mask 7) 30
第四章 元件量測結果分析 31
4.1 歐姆接觸量測 31
4.2 電容量測 34
4.3 閘極氧化層耐壓特性 37
4.4 Digital Etch實驗分析 39
4.5 元件正向電性量測 46
4.5.1 直流DC模式下之電性量測 46
4.5.2 直流DC模式下照射UV之電性量測 46
4.5.3 脈衝(Pulse)模式下照射UV之電性量測 47
4.6 升溫量測 58
4.7 通道於不同晶向探討 63
第五章 結論與未來工作 64
參考文獻 65

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