臺灣博碩士論文加值系統

為了改善電力電子系統的能量轉換效率，我們應該要設法降低半導體功率元件在導通和切換時的能量損耗，而碳化矽功率元件正是這方面的首選，因為其優異的材料性質讓它們特別適合做高電流密度和高溫的應用。在各種功率元件中，碳化矽功率金氧半電晶體的高頻切換能力使其最受矚目，然而，低通道載子遷移率、高表面態密度和劣等的氧化層穩定度一直都是該元件發展中的阻礙，我們必須克服這些難題，其中一個辦法就是提出新的元件結構。
本論文藉由Silvaco軟體設計碳化矽雙溝槽式累積型金氧半功率電晶體，針對元件結構進行製程和電性模擬，就元件內部各區塊的濃度、深度和寬度等作最佳化分析，最後預計達到元件崩潰電壓1200伏特、導通電阻5 以下 及啟動電壓(Vth)2至4伏特的規格。

To improve the energy conversion efficiency of power electronic systems, it is necessary to reduce the power losses during switching and on-state conduction of power semiconductor devices. SiC power devices are the best candidates because they have excellent material properties for high power density and high temperature applications. Among all sorts of power devices, SiC power MOSFET attracts the most attention because of its high frequency switching capability. However, low channel mobility, high interface state density as well as inferior oxide reliability still remain to be major obstacles to the development of SiC power MOSFET over the years. Therefore, it is imperative for us to overcome these issues. One way is to devise new power device structure.
In this thesis, a novel device structure called “dual trench ACCUFET” is proposed. We then simulate its electric performance and fabrication processes by using Silvaco software. After that, we analyze the simulation results and optimize the device’s performance by parameter, such as doping concentration, thickness and width, hoping to design a device exhibiting the breakdown voltage of 1200 volts, the on-resistance under 5 and the threshold voltage between 2 to 4 volts.

誌謝…………………………………………………………………………………….i
中文摘要………………………………………………………………………………ii
ABSTRACT…………………………………………………………………………..iii
CONTENTS…………………………………………………………………………..iv
圖目錄……………………………………………………………………….………..vi
表目錄………………………………………………………………….……….……..x
第一章 緒論…………………………………………………………………………..1
1.1前言…………………………………………………………………...……….1
1.2 碳化矽材料性質……………………………………………………………...2
1.2.1 高溫應用………………………………………………………………3
1.2.2 高壓應用………………………………………………………………5
1.2.3 高效率應用……………………………………………………………6
1.3 研究動機…………………………………………………………...…………8
第二章 元件結構原理介紹………………………………………………………......9
2.1 理想開關元件特性…………………………………………………………...9
2.2 常見功率電晶體元件種類簡介…………………………………………….10
2.2.1雙極性接面電晶體 (BJT)……………………………………………11
2.2.2接面場效電晶體 (JFET)……………………………………………..12
2.2.3絕緣閘極雙極性電晶體 (IGBT)………………..…………………...13
2.2.4功率金氧半場效電晶體 (power MOSFET)………………...………14
2.3 碳化矽功率MOSFET發展中的困難…………………………………...…17
2.3.1 power MOSFET元件特性的發展理論極限……………………...…17
2.3.2低載子通道遷移率…………………………………………………...20
2.3.3氧化層穩定度………………………………………………………...22
2.4 ACCUFET (累積型MOSFET)………………………………………………24
2.5 碳化矽製程技術…………………………………………………………….27
2.5.1碳化矽中dopant之擴散係數………………………………..………27
2.5.2離子佈植與退火……………………………………………………...28
2.5.3氧化層生長…………………………………………………………...28
2.5.4反應式離子蝕刻(RIE)………………………………………………..29
2.6 元件製作流程……………………………………………………………….29
第三章 模擬軟體環境設定…………………………………………………………35
第四章 模擬結果分析與討論………………………………………………………39
4.1 元件初步設計……………………………………………………………….39
4.2 元件模擬電性結果………………………………………………………….42
4.2.1順向導通特性………………………………………………………...42
4.2.2逆向偏壓特性………………………………………………………...47
4.3 磊晶層濃度對元件電性之影響…………………………………………….49
4.4 磊晶層厚度對元件電性之影響…………………………………………….52
4.5 P+區域佈植濃度、深度和底部氧化層厚度對元件電性之影響…..……...53
4.6 P+ Shield結構對元件電性之影響……………………………………...…..61
4.7 溝槽寬度對元件電性之影響……………………………….………………67
4.8 溝槽深度和通道寬度對元件電性之影響……………………………….…69
4.9 雙層磊晶結構…………………………………………...…………………..72
4.10閘極氧化層厚度對元件電性之影響…….………………….……………..76
第五章 結論與未來展望……………………………………………………………79
REFERENCES…………………………….………………………………………..80

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