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研究生： 余湘璘
Hsiang-Lin Yu
論文名稱： 氮化鋁鎵/氮化鎵高電子遷移率場效電晶體元件結構與鈍化方式對高頻率及高功率之特性分析
Effect of Layer Structure and Passivation on High Frequency and High Power Characteristics in AlGaN/GaN HEMTs
指導教授： 詹益仁
Yi-Jen Chan
林恒光
Heng-Kuang Lin
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
畢業學年度： 97
語文別： 中文
論文頁數： 133
中文關鍵詞： 氮化鋁鎵 、氮化鎵 、高電子遷移率場效電晶體 、鈍化層 、堀入式閘極
外文關鍵詞： High power, Passivation, Recessed Gate, HEMT, AlGaN/GaN
相關次數： 點閱：33  下載：0 
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    • 氮化鋁鎵/氮化鎵高速電子遷移率場效電晶體(AlGaN/GaN HEMT)，由於擁有卓越的載子傳輸特性，因此常被應用在高功率、高溫度以及高頻率的電路操作中。如何最佳化元件結構以及鈍化製程發展即為此篇論文的重點敘述。
    在最佳化元件結構部份，我們探討不同元件結構對於元件特性的影響，包括堀入式閘極、高掺雜表面層於歐姆接點及低串聯寄生電阻結構－搭配發展出電子束微影製程，驗證了AlGaN/GaN HEMT次微米元件優異之微波功率性能，在高頻特性部分，電流增益截止頻率(fT)與閘極長度(LG)的乘積可以高達20 GHz-um。
    在元件鈍化層製程的最佳化部份，我們提出一種可同時成功提昇元件高頻及功率特性的鈍化層覆蓋方式，在移除高摻雜層後馬上覆蓋鈍化層Si3N4或是SiO2，相較於傳統方式鈍化之元件，明顯改善了元件表面與鈍化層介面特性，成功抑制缺陷效應所造成的電流侷限。
    就功率元件因為基板散熱不佳而造成自我發熱的問題，我們利用不同閘極寬度並聯大功率元件，從電性上退化的探討證明散熱對於高功率元件的重要性，並利用紅外線熱影像分析了元件操作時表面溫度的分布。

    AlGaN/GaN HEMTs have attracted great interest for high-power, high-temperature, and high-frequency applications because of their superior carrier transport properties. This thesis focuses on optimization of device structure and passivation process, and their correlation with device performance.
    Based on the same epitaxy materials, we investigated the effect of different Al0.26Ga0.74N/GaN HEMT device structure on DC and RF performance. Results show that n+-GaN cap kept under ohmic metals for lowering contact resistance, an appropriate gate recess depth for improving charge modulation capability, and cap removal in device access region for miminizing source resistance are determined as best structure for achiving highest frequency performance. Improved speed performance in both micron and submicron devices were demonstrated. A 0.5 um T-gate device yielded a high fT×LG product of 20 GHz-um.
    Plus, we reported the fabrication of AlGaN/GaN HEMT with improved DC, high frequency and microwave power performances by employing an alternative passivation approach. A pretreated AlGaN surface is provided by dry etching n+-GaN cap layer and RTA annealing ohmic contacts right before Si3N4 or SiO2 passivant was deposited. Pulsed I-V characteristics show that the pseudo in-situ passivation process successfully eliminates trapping effect at Si3N4 or SiO2 and AlGaN interface which is considered to be the important factor for the performance enhancement. The issues of the drain current collapse and the power degradation induced by the surface traps are also successfully improved.
    As for the issue of self heating, power devices with different layouts are addressed. Thermal IR microscopy was used to detect the device surface temperatures under various dc power consumptions.

    摘要 I Abstract II 目錄 III 圖目錄 VIII 表目錄 XV 第一章 緒論 1 1.1 GaN材料特性及發展趨勢 1 1.1.1 AlGaN/GaN HEMT市場發展與應用 1 1.1.2 優越的材料特性 3 1.2 研究動機 13 1.2.1 AlGaN/GaN HEMTs元件結構簡介與發展 13 1.2.2 AlGaN/GaN HEMT鈍化層發展 14 1.3論文架構 15 第二章AlGaN/GaN HEMTs 材料分析與製程 16 2.1 AlGaN/GaN HEMTs 材料分析與製程簡介 16 2.2 AlGaN/GaN磊晶結構材料分析 16 2.2.1磊晶材料分析 17 2.3 AlGaN/GaN元件製作流程 19 2.3.1 堀入式閘極AlGaN/GaN HEMTs 20 2.3.2 AlGaN/GaN HEMT 鈍化層之研發製作 21 2.3.3 AlGaN/GaN HEMTs 功率元件 24 第三章AlGaN/GaN HEMTs量測特性結果比較 27 3.1 AlGaN/GaN HEMTs量測特性簡介 27 3.2 堀入式閘極AlGaN/GaN HEMTs 27 3.2.1表面結構特性分析 27 3.2.2 直流特性分析 30 3.2.3崩潰電壓特性分析 33 3.2.4 高頻特性分析 35 3.2.5 功率特性分析 36 3.3 GaN/AlGaN/GaN HEMTs 元件特性分析 38 3.3.1 GaN/AlGaN/GaN HEMTs簡介 38 3.3.2 GaN覆蓋層特性表現 39 3.3.3崩潰電壓特性分析 42 3.3.4高頻特性分析 43 3.3.5功率特性分析 44 3.4 小線寬堀入式閘極之AlGaN/GaN HEMTs 元件特性分析 45 3.4.1 小線寬堀入式閘極之AlGaN/GaN HEMTs 簡介 45 3.4.2小線寬堀入式閘極之 AlGaN/GaN HEMTs製作方式 45 3.4.3直流特性分析 47 3.4.4高頻特性分析 48 3.5 AlGaN/GaN HEMT鈍化層的發展 53 3.5.1 AlGaN/GaN HEMT 鈍化層簡介 53 3.5.2 直流特性分析 53 3.5.3 高頻特性分析 59 3.6 功率AlGaN/GaN HEMTs 66 3.6.1功率AlGaN/GaN HEMTs簡介 66 3.6.2直流特性分析 67 3.6.3 高頻特性分析 69 3.6.4 熱影像特性分析 70 第四章 AlGaN/GaN HEMTs結構特性探討與比較 73 4.1 AlGaN/GaN HEMTs結構特性探討簡介 73 4.2 汲極電流開關比與次臨限斜率特性分析 73 4.2.1 汲極電流開關比與次臨限斜率簡介 73 4.2.2 堀入式閘極 AlGaN/GaN HEMTs 74 4.2.3 鈍化之AlGaN/GaN HEMTs 76 4.3 閘極漏電流機構 78 4.3.1閘極漏電流機構簡介 78 4.3.2 AlGaN/GaN HEMT特性 78 4.4 衝擊離化對AlGaN/GaN HEMTs 之影響 81 4.4.1 AlGaN/GaN HEMTs 衝擊離化效應簡介 81 4.4.2 AlGaN/GaN HEMT特性 82 4.4.3 鈍化AlGaN/GaN HEMT特性 83 4.5 缺陷對AlGaN/GaN HEMTs之影響 85 4.5.1 AlGaN/GaN HEMTs之缺陷效應簡介 85 4.5.2 脈波電流–電壓量測系統架設方法 86 4.5.3 鈍化層對表面缺陷效應的影響 88 4.6 電容–電壓特性量測 93 4.6.1 AlGaN/GaN HEMTs 之電容–電壓特性簡介 93 4.6.2 鈍化之AlGaN/GaN HEMTs電容-電壓特性 94 4.6.3 表面態對電容-電壓特性的影響 96 第五章 結論與未來發展 98 5.1結論 98 5.2未來發展 99 【參考文獻】 101 附錄 106 AlGaN/GaN HEMT 製作流程 106 堀入式閘極AlGaN/GaN HEMT 106 雙層鈍化層之AlGaN/GaN HEMT 109 功率AlGaN/GaN HEMT 113

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