臺灣博碩士論文加值系統

本篇論文提出新穎的4H-SiC溝渠式接面位障蕭基二極體，結合了floating guard ring 的邊緣終結結構，擁有低漏電流與低導通電壓的優點。藉由溝渠式的結構設計，可降低表面電場並減少蕭基位障降低效應，故此結構可使用低功函數的蕭基金屬，降低導通電壓而不用忍受高的反向漏電流。在元件設計、製作以及特性探討上，針對不同的離子佈植間距、溝渠深度、基板濃度、蕭基金屬等特性分析，並以模擬去預測元件特性。TJBS元件於反向偏壓600伏特時，其漏電流密度較JBS小十倍，其中溝渠深度2μm的Ti-TJBS元件，順向電壓降為0.96 V，反向漏電流密度小於1×10-7 A/cm2；在室溫與升高溫度時，TJBS元件相較於所製作的SBD與JBS元件，擁有更低的漏電流；當TJBS操作於高電流密度及高溫時，可觀察到有導電率調變的現象。另一方面， Ti-JBS元件經由500 °C 5分鐘的熱退火，可增加其蕭基位障高度，由0.83 eV增加至1.14 eV，導通電壓由0.5 V增加至1 V，達到約1 kV的崩潰電壓。

This thesis presents a novel structure of 4H-SiC trench junction barrier schottky diode with floating guard ring edge termination, which has low leakage current and low turn-on voltage. In addition, by incorporating the trench structure in the design, the electric field at the schottky interface and the corresponding barrier lowering effect can be reduced. Therefore, the proposed structure can be fabricated with low work function metal to reduce turn-on voltage without suffering high reverse leakage current. Different p+ spacing, trench depth, schottky metal and doping concentrations were designed, fabricated and characterized. Simulations were also performed to predict device characteristics. TJBS device has leakage current density ten times smaller than the traditional JBS device at 600 V. The forward voltage drop of 2 μm trench Ti-TJBS is 0.96 V while the reverse current density is less than 1×10-7 A/cm2. At room temperature as well as at elevated temperature, the proposed TJBS device has lower leakage current density than that of the SBD and JBS devices. Conductivity modulation behavior is observed in TJBS at high current densities and high temperatures. On the other hand, the blocking voltage of Ti-JBS about 1 kV was achieved using a thermal treatment to increase Schottky barrier height, which is increased from 0.83 eV as deposited to 1.14 eV after 500 °C anneal for 5 minutes. The turn-on voltage is increased from 0.5 V to 1 V.

第一章 序論 1
1.1 碳化矽材料簡介 1
1.2 研究動機與研究大綱 4
1.3文獻回顧 7
第二章 元件基本結構原理及元件模擬 10
2.1 蕭基二極體原理特性 10
2.2接面位障蕭基二極體 13
2.3 邊緣終結保護結構 15
2.3.1簡介與基本原理 15
2.3.2邊緣終結結構種類 15
2.4 元件設計及特性模擬 16
2.4.1離子佈植深度特性模擬 16
2.4.2離子佈植區域特性模擬 17
2.4.3溝渠式接面位障蕭基二極體特性模擬 18
第三章 光罩設計與元件製程 26
3.1 基板濃度 26
3.2 元件設計 27
3.3 光罩設計 29
3.4 實驗製程 30
3.4.1 實驗製程步驟 30
第四章 實驗量測結果與討論 43
4.1量測簡介 43
4.2 SBD與JBS特性分析 43
4.3 TJBS順向偏壓特性 52
4.3.1溝渠深度特性分析 52
4.3.2元件尺寸分析 54
4.3.3 離子佈植與溝渠間距分析 56
4.3.4 基板濃度分析 60
4.3.5 蕭基金屬分析 62
4.3.6導電率調變現象 65
4.4 TJBS反向偏壓特性 70
4.4.1溝渠深度特性分析 70
4.4.2 離子佈植與溝渠間距分析 72
4.4.3崩潰電壓 74
4.4.4蕭基位障對漏電流分析 77
4.5溫度變化特性 78
4.5.1順向偏壓特性 78
4.5.2反向偏壓特性 79
4.6電容電壓特性 81
4.7掃瞄式電子顯微鏡分析 83
第五章 結論與未來展望 85
參考文獻 87

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