應用於低雜訊放大器之三閘極砷化銦高電子遷移率 電晶體之研究

近年來，次微米級線寬的平面電晶體已經成為半導體工業的主流，許多研究仍然致力於縮小閘極寬度。但隨著元件尺寸的縮小，有些問題會愈發明顯，例如閾值電壓絕對值增加以及漏電流上升等短通道效應。因此，為了更進一步提升元件特性，尋找新的通道材料或研發新的製程方法都是可行的。由於三五族的砷化銦材料與磷化銦基板晶格匹配，以及具有高電子遷移率和低閾值電壓，因此在此研究中，我們使用砷化銦通道高電子遷移率電晶體提升電子傳輸速度與低耗能的特性。此外，透過兩次電子束微影以及蝕刻技術，在此研究中成功的使通道和閘極形成立體結構，即三閘極電晶體，有效地增加閘極與通道之間的接觸面積。此研究也比較了立體與平面結構電晶體之間的電性差異。結果顯示三閘極電晶體比平面電晶體在低偏壓下(VDS=0.5V)具有更好的閘極控制能力，元件不僅再邏輯特性上展現了較低的次臨界擺幅與較大的開關電流比，而且增益轉導也得到提升，偏壓上升至VDS=1V時，元件的次臨界特性以及開關比又有更進一步的改善。三閘極電晶體比平面電晶體有更高的增益且有效抑制雜訊，由這些研究結果可以證實，三閘極砷化銦通道高電子遷移率電晶體極有潛力作為未來後矽半導體世代高頻低雜訊電晶體的使用。

關鍵字

砷化鎵；高電子遷移率電晶體；三閘極結構；低雜訊放大器

並列摘要

Recently, the planar transistors with sub-micro-scale gates have already been the trend of semiconductor industry. Many researches still focus on reducing gate length. However, as the transistor scales down, many problems start appearing, such as VTH roll-off and off-state leakage, or so called short channel effect. Therefore, searching a new channel material and a corresponding fabrication process are urgent to improve the device characteristics. InAs channel lattice possesses with high electron mobility and low threshold voltage. It matches with InP substrate as well. As a result we use InAlAs/InAs/InP high electron mobility transistors (HEMTs) to achieve high-speed and low power consumption in this study. Furthermore, by double electron beam lithography and etching, 3-D structure HEMTs that increase the area between gate and channel has been successfully fabricated. This study also compared electrical characteristics between 3-D and planar devices. The results show that the 3-D devices has better gate controllability, not only improving logic performance likes SS and ION/IOFF ratio, but also increase GM (VDS=0.5V). When VDS increases to 1V, the subthreshold characteristics and Ion/Ioff ratio are further improved, resulting in better noise performance. Compared to planar device, not only Associated Gain (dB) has been improved, but also Noise figure is reduced. These results demonstrate that Tri-Gate InAs HEMTs are suitable for high-frequency and low noise applications.

並列關鍵字

GaAs ； HEMTs ； Tri-Gate ； LNA

參考文獻

[1] Moore, Gordon E. "Progress in digital integrated electronics." IEDM Tech. Digest 11 (1975).

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[2] Eastman, Lester F., et al. "Undoped AlGaN/GaN HEMTs for microwave power amplification." Electron Devices, IEEE Transactions on 48.3 (2001): 479-485.

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[3] Bollaert, S., et al. "Metamorphic In/sub 0.4/Al/sub 0.6/As/In/sub 0.4/Ga/sub 0.6/As HEMTs on GaAs substrate." Electron Device Letters, IEEE 20.3 (1999): 123-125.