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| 研究生： |
蔡政倫 Tsai, Cheng-Lun |
|---|---|
| 論文名稱： |
矽基板氮化鎵高頻電容性元件及主動元件設計與製作 Design and Fabrication of GaN on Si Capacitance and Active Devices |
| 指導教授： |
徐碩鴻
Hsu, Shuo-Hung |
| 口試委員: |
連羿韋
Lian, Yi-Wei 章殷誠 Chang, Yin-Cheng |
| 學位類別： |
碩士 Master |
| 系所名稱： |
電機資訊學院 - 電子工程研究所 Institute of Electronics Engineering |
| 論文出版年： | 2021 |
| 畢業學年度： | 109 |
| 語文別： | 中文 |
| 論文頁數： | 116 |
| 中文關鍵詞： | 氮化鎵 、高頻元件 、高電子遷移率電晶體 、高頻模擬 、被動元件 、功率元件 |
| 外文關鍵詞： | GaN, High frequency device, Passive device, HEMTs, Power device, High frequency simulation |
| 相關次數： | 點閱：3 下載：0 |
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氮化鎵材料有著寬能隙、良好的熱傳導特性及高臨界電場等優點，讓氮化鎵成為高頻功率元件材料的首選，在傳統的HEMT製程中，通常是使用鈦(Ti)/鋁(Al)/鎳(Ni)/金(Au)作為歐姆接觸的金屬結構，並使用鎳(Ni)/金(Au)作為蕭特基閘極的金屬結構，使用金能夠大幅降低歐姆接觸的電阻同時具備良好的抗氧化能力，然而金的價格昂貴，在退火之後表面型態會變得非常粗糙，並且在大部分的機台中，金被視為高汙染性金屬而被禁止進入腔體，導致含有金的元件製程會受到限制，因此找到新的金屬製程取代金成為當前的重要課題。
本次研究以Ti/Al取代傳統的Ti/Al/Ni/Au歐姆接觸，並製作了線寬達到0.2μm的multi-finger gate，為了設計高頻電路，將主動元件的製程整合無金被動元件製程，設計出能夠應用於5G通訊頻段的傳輸線及電容，並建構了被動元件的模擬環境，電容的容值誤差達到10%，傳輸線特徵阻抗的誤差達到6%，電路的虛部值誤差達到4%。
本次研究設計出50Ω及75Ω特徵阻抗傳輸線，電容部分可應用的容值範圍為0.22pF至3.4pF，可應用最高頻率可達25GHz。主動元件的電流密度達到251 mA/mm，gm達到75.3 ms/mm，fT達到30.6GHz，fmax達到14.4GHz，在功率量測部分，Pout最大可以達到18.72dBm，Gain最大可達到13.06dB，PAE最大可以達到24.56%。
Gallium Nitride (GaN)-based materials have the advantages of wide band gap, high electron saturation velocity, high critical electric field and low on-resistance. Therefore, GaN-based devices have received considerable attention in high power and high frequency applications. In conventional HEMT process flow, Ti/Al/Ni/Au metal stack is usually used as ohmic contact’s metal stack, Ni/Au metal stack is usually used as schottky gate’s metal stack. Au has the advantages of low resistivity and Anti-oxidant capacity. However, Au’s price is more expensive than other metal material, and Au’s surface will be rough after high temperature annealing, either. In addition, many process machines prohibit Au entry because of Au’s high pollution, confining the device’s process which contains Au. Therefore, discovering the new metal process for replacing Au is the important current issue.
In this work, we replace the traditional Ti/Al/Ni/Au ohmic contact with Ti/Al metal stacks, and we fabricate 0.2μm multi-finger gate. To design high frequency circuit, we integrate active device process with Au-free passive device process, designing capacitors and transmission lines which can be used in 5G frequency band, and we also build the simulation environment. Compared to the real data, capacitance’s deviation is 10%, deviation of transmission line’s characteristic impedance deviation is 6%, deviation of circuit’s imaginary part is 4%.
In this work, we design 50Ω and 75Ω characteristics impedance transmission line, In the part of capacitor, capacitance from 0.22pF to 3.4pF can be operated, and the highest applicable frequency can reach 25GHz. In active device part, the maximum current density IDmax, maximum transconductance gm, current gain cutoff frequency fT, maximum oscillation frequency fmax, maximum output power Pout, maximum power gain and maximum power added efficiency PAE are 251mA/mm, 75.3ms/mm, 30.6GHz, 14.4GHz, 18.72dBm, 13.06dB and 24.56%.
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