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研究生： 林恩碩
En-Shuo Lin
論文名稱： T型閘極氮化鋁銦(鎵)/氮化鋁/氮化鎵高電子遷移率電晶體製作與特性分析
Fabrication and Characterization of T-gate AlIn(Ga)N/AlN/GaN High Electron Mobility Transistors
指導教授： 綦振瀛
Jen-Inn Chyi
口試委員:
學位類別： 碩士
Master
系所名稱： 資訊電機學院 - 電機工程學系
Department of Electrical Engineering
論文出版年： 2018
畢業學年度： 107
語文別： 中文
論文頁數： 109
中文關鍵詞： 氮化鎵高電子遷移率電晶體 、T型閘極 、氮化鋁銦鎵 、基板寄生效應 、電流截止增益 、功率截止增益
外文關鍵詞： GaN HEMT, T-gate, AlInGaN, substrate parasitic effect, fT, fmax
相關次數： 點閱：13  下載：0 
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    • 現今氮化銦鎵位障層高頻元件因具高二維電子氣且高輸出功率吸引很多團隊應用在高頻元件上。然而其仍受到介面粗糙度以及銦自聚效應等限制，因此發展四元氮化鋁銦鎵位障層，具較少的銦含量，減少銦原子的自聚效應，降低成分不均勻性，加入鎵原子可提高互容性，因此四元位障層具較佳的位障層磊晶品質。於元件結果顯示，四元氮化鋁銦鎵位障層具高能隙特性，在Lgd=2 µm、Lg= 400 nm之元件崩潰達到81 V較三元位障層57 V突出。高頻特性顯示三元與四元磊晶片fT/fmax分別為18/24.5 GHz與35.3/40.3 GHz，萃取小訊號參數發現氮化鋁銦鎵位障層具有較高本質轉導值。
    為提高元件高頻操作，閘極線寬須微縮，然而將遭遇閘極寄生電阻過大使功率截止增益受限。運用T型閘極的優勢降低閘極寄生電阻與閘極寄生電容，使用三層光阻ZEP-A7/LOR/ZEP-A7開發T型閘極，當閘極線寬由400 nm微縮至160 nm時，T型閘極微影製程需較佳的身寬比才能將金屬鍍完整。元件特性部分相同Lsd下，汲極飽和電流密度由522提升至893 mA/mm，轉導由287上升至370 mS/mm。高頻特性fT/fmax由35.3/40.3提高至83/95 GHz，主要和線寬微縮時本質轉導提升以及閘極寄生電容下降有關。閘極由400 nm微縮至160 nm，因金屬截面積的提高外部閘極寄生電阻由21歐姆降至7歐姆，成功顯示T型閘極製程效果。本論文成功驗證氮化鋁銦鎵材料與T型閘極優勢，適用於高功率放大器之應用。此外吾人考慮基板寄生效應，計算後並利用ADS模擬軟體在小訊號電路上扣除，得到最後的fmax為103GHz，顯示低阻值矽基板將會影響元件高頻特性。

    Lattice matched Al0.83In0.17N/GaN high electron mobility transistors (HEMTs) have attracted a lot of interests as an alternative to the most matured AlGaN/GaN HEMTs for high power millimeter-wave devices because of its high density two dimensional electron gas (2DEG) at the heterointerface, even with sub-10 nm barrier. However, in spite of having such advantages over its AlGaN counterparts, it suffers from In segregation, compositional inhomogeneity and high off-state leakage current. AlInGaN/GaN HEMTs recently emerges as one of the promising candidate for mm-wave power applications. It is reported to have highest miscibility after AlGaN, among all the III-nitride materials. However, many of its properties and device performances are yet to be explored before its successful commercial deployments. This thesis aims at comparing the DC and RF performances of AlInN/GaN and AlInGaN/GaN HEMTs grown on 150 mm silicon (111) substrates. Devices fabricated with Lg= 0.4 µm/Lgd= 2 µm show off-state breakdown voltage of 81V and 57V with AlInGaN and AlInN barriers respectively. Furthermore, the AlInGaN/GaN and AlInN/GaN HEMTs with the same dimensions exhibit a current gain cut-off frequency (fT) of 35.3 GHz and 18 GHz and a power gain cut-off frequency (fmax) of 40.3 GHz and 24.5 GHz respectively. Extracted small signal parameters indicate, higher intrinsic transconductance (gmi) is one of the reasons for significantly higher fT/fmax in AlInGaN barrier HEMTs.
    Highly conductive T-gate with low input resistance and small footprint is desirable for devices operating at mm-wave frequency. However, it introduces additional gate parasitic capacitance, resulting lower fT. Therefore, highly optimized T-gates are needed to balance the fT/fmax ratio. A tri-layer photoresist of ZEP-A7/LOR/ZEP-A7 is developed to obtain high profile T-gates. The Idss increases from 522 mA/mm to 893 mA/mm, the transconductance increases from 287 mS/mm to 370 mS/mm and fT/fmax increase from 35.3/40.3 GHz to 83/95 GHz in AlInGaN HEMT by scalling down Lg from 0.4 µm to 0.16 µm. A reduction in parasitic gate capacitance and parasitic gate resistance from 21 ohm to 7 ohm may be attributed to the improved RF performances. This work further demonstrates that the AlInGaN/GaN HEMTs with highly optimized T-gates are excellent candidates for high power mm-wave applications. Furthermore, I consider substrate parasitic effect and remove substrate parasitic parameters by ADS simulation program. The extracted fmax is 103 GHz which indicated low resistivity silicon substrate will reduce high frequency result.

    目錄 論文摘要……………………………………………………………………....i Abstract……………………………………………………………………....iii 誌謝…………………………………………………………………………..iv 目錄…………………………………………………………………………...v 圖目錄……………………………………………………………………….vii 表目錄………………………………………………………………………..xi 第一章 導論………………………………………………………….............1 1.1 前言…………………………………………………………....1 1.2 三族氮化物異質結構極化效應………………………………3 1.3 氮化鎵元件發展現況…………………………………………7 1.4 研究動機與論文架構………………………………………..12 第二章 氮化鎵異質結構場效電晶體之高頻量測………………...............14 2.1 高頻量測原理………………………………………………..14 2.2 小訊號電路模型分析………………………………………..17 2.3 小訊號參數萃取……………………………………………..19 2.4 本章總結……………………………………………………..26 第三章 T-型閘極製程開發與元件製作……………………………………27 3.1 前言…………………………………………………………..27 3.2 製程開發……………………………………………………..29 3.3 T-型閘極元件製程流程……………………………………...34 3.4 製程分析與檢視……………………………………………..42 3.5 本章總結……………………………………………………..46 第四章 AlIn(Ga)N/AlN/GaN HEMT特性分析……………………………48 4.1 前言…………………………………………………………..48 4.2 AlInN與AlInGaN HEMT直流特性分析………………….50 4.3 AlInN與AlInGaN HEMT高頻特性分析………………….54 4.4 0.16 µm閘極之AlInGaN HEMT特性分析………………..57 4.5 本章總結……………………………………………………..64 第五章 結論與未來展望…………………………………………………...66 附錄A不同位障層鋁含量之氮化鋁銦/氮化鋁/氮化鎵高電子遷移率電晶體之直流特性研究………………………………………………...…..68 A1.1 磊晶結構設計……………………………………………...68 A1.2 Hall量測、能帶模擬分析…………………………...……...71 A1.3 HEMTs蕭特基元件製作流程……………………………..74 A1.4 不同鋁含量之氮化鋁銦位障層特性分析………………...78 A1.5 本章總結…………………………………………………...86 參考文獻…………………………………………………………………….87

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