應用於毫米波之矽基板氮化銦鋁/氮化鎵高電子遷移率電晶體設計與製作

Design and Fabrication of InAlN/GaN HEMTs on Silicon Substrates for Millimeter-Wave Applications

林辰憶(Chen-Yi Lin)

指導教授 ： 徐碩鴻

國立清華大學/電機資訊學院/電子工程研究所/碩士(2014年)

摘要

近年來，由於無線通訊技術的發達，例如手機、無線網路、無線充電及車用感應器…等；使得高頻及高功率電晶體的需求增加，氮化鎵高電子遷移率電晶體(GaN-based HEMTs)，優越的材料特性，成為近年來非常受矚目的研究重點。AlGaN/GaN HEMTs具有高電子遷移率及在高電場下可維持高電子飽和速度，非常適合毫米波的應用。另外，為了降低成本及未來可能與CMOS電路作整合，將GaN元件製作於矽(Si)基板上已成為趨勢，元件的特性也已經有顯著的成果，然而，AlGaN/GaN HEMTs的可靠性(reliability)仍然是個問題。
本論文著重於矽基板(Si substrates)之InAlN/GaN HEMTs之高頻元件設計及分析，氮化銦鋁/氮化鎵(InAlN/GaN)接面具備晶格匹配特性，可望提高元件的可靠性，且在較薄的InAlN厚度下，仍可維持高濃度的二維電子氣通道，對電晶體的高頻特性非常有幫助。
本論文研究之矽基板InAlN/GaN HEMTs元件中，掘入式T型閘極結構的高頻特性表現，f_T可達50GHz以上，f_max可達100GHz以上。利用線型閘極加入蕭特基源極/汲極外延層結構，亦可成功地提升高頻特性。我們藉由高頻等效電路模型對元件進行分析，根據等效模型參數，指出高頻特性主要是被寄生效應所限制，所得到的結果也可以幫助我們了解，如何進一步改善元件的特性及InAlN/GaN 成長於矽基板上的磊晶結構。

關鍵字

氮化鎵 ； 氮化銦鋁/氮化鎵 ； 高電子遷移率電晶體 ； 矽基板 ； 高頻

並列摘要

In recent years, the wireless technology has been used widely for different applications such as mobile phones, wireless charging, and automotive sensors. This leads to an exponential increased demand of high frequency and high power transistors. GaN-based devices, owing to the superior material properties, have attracted significant attentions and become a popular research topic over the past decade. The AlGaN/GaN high electron mobility transistors (HEMTs) with an excellent mobility and high saturation velocity under a high electric field are suitable for millimeter wave applications. More recently, these devices fabricated on the silicon substrate with lower cost and possibility to integrate with CMOS devices showed significant progress in device characteristics. However, the transistor reliability is still an issue.
This thesis focuses on design and analysis of the high-frequency device of InAlN /GaN HEMTs on the Si substrates. The lattice-matched InAlN/GaN interface is expected to improve the device reliability issue. The high carrier density in the 2DEG channel can also enhance the transistor frequency response. The fabricated devices show a best f_T and f_max up to 50 GHz and 101 GHz respectively with a gate-recess structure. The devices with Schottky drain/source extension also result in improved high frequency performance. We analyze the devices in details by using the small-signal equivalent circuit model. Based on the analysis of the equivalent circuit model parameters, the dominant parasitic effects to limit the device RF characteristics have been identified. The obtained results can be used to understand how to further improve the device performance regarding the device fabrication and the epitaxy structure of the InAlN/GaN on the Si substrate.

並列關鍵字

GaN ； InAlN/GaN ； HEMT ； Silicon Substrate ； high frequency

參考文獻

[1]J.A. del Alamo, J. Joh, “GaN HEMT reliability,” Microelectronics Reliability, vol. 49, Issues 9-11, Nov. 2009.

[3]Ambacher, “Growth and applications of group III-nitrides,” J. Physics D (Applied Physics), vol. 31, pp. 2653-2710, 1998.

[4]Likun Shen , “Advanced Polarization-Based Design of AlGaN/GaN HEMTs,” PhD thesis, University of California, Santa Barbara, 2004.

[5]B. Gelmont, K. Kim, and M. Shur, “Monte Carlo Simulation of Electron Transport in Gallium Nitride,” J. Appl. Phys., 74 (3), pp. 1818-1821, 1993.

[7]J. Kuzmik, “InAlN/(In)GaN high electron mobility transistors： some aspects of the quantum well heterostructure proposal,” Semicond. Sci. Technol. 17 (2002)540.