砷化銦通道之高電子遷移率空乏型與增強型之高頻與邏輯數位之元件特性研究

Abstract

近年來毫米波、次毫米波頻段的應用在無線電頻率特別頻繁，對人類已經產生重大的影響。其所應用的範圍包括有交通指引、行動通訊、雷達系統、軍事國防等；除此之外，其他一些仍在發展中的應用例如醫藥分析、家園防護系統、高解析度影像感測系統等，其研究也如火如荼的進行中。而尋找在高頻頻段下仍擁有極高增益、低雜訊的元件是這類應用的重要關鍵。由於三五族砷化銦鎵材料的高電子遷移率以及量子井場效電晶體優異的能帶設計，因此三五族砷化銦鎵通道量子井場效電晶體在這方面的應用展現極大潛力。 在此研究中，成功的製作了六十奈米閘極線寬的砷化銦高電子遷移率電晶體，並且透過先進的二次閘極蝕刻以及白金閘極掘入技術，使元件展現優異的高頻特性。此研究比較了在低操作偏壓下(VDS=0.5V)使用此先進製程技術的砷化銦量子井場效電晶體與未使用此製程的元件，發現透過此兩先進製程步驟，使元件有空乏型與增強型，兩種模式，元件展現較佳飽和電流、較低輸出電導、較小負截止電壓，以及較高的電流增益截止頻率 (可分別達到153GHz以及288GHz)。由這些特性可以得知，六十奈米的砷化銦量子井場效電晶體是適用於高增益、以及低操作偏壓的高頻元件應用。 這份論文的最後，另外針對六十奈米砷化銦高電子遷移率電晶體於未來高速邏輯電晶體運用做評估，發現在低偏壓下(VDS=0.5V)元件展現相當優異的邏輯特性，包括其汲極引致能障下降是相當低的70mV/V，而次臨界擺幅也是相當低的67mV/decade，此外，此元件的閘極延遲時間低於5.0 p sec，而與Si NMOSFET做比較，其閘極延遲時間也是較低的。而這些研究結果可以證實六十奈米砷化銦量子井場效電晶體是極有潛力作為未來後矽半導體世代高速邏輯電晶體的使用。

In recently years, wireless communication applications at millimeter wave band and sub-millimeter wave bands have received a lot of momentum. The applications include radar systems, cellular backbone, wireless systems, national weaponry, traffic guidance, etc. Besides, emerging millimeter wave applications such as homeland security, medical diagnosis, and high-resolution image sensor are also in development rapidly. Therefore, development of the device possessing both high frequency features and low noise characteristics is becoming urgent. High indium content InGaAs-based HEMTs are particularly promising because the excellent electrical properties of InxGa1-xAs material and the superior band-gap design of HEMT. In this study, the 60 nm InAs HEMTs processed with advanced two-step recess and Pt gate sinking technologies for RF applications were fabricated. Depletion and Enhancement Mode InAs Channel HEMTs of the developed 60 nm InAs HEMTs with these advanced processes exhibit better performance than the conventional InAs HEMTs at low applied voltage such as better current saturation, lower output conductance (go), smaller negative threshold-voltage (VT), higher current-gain cut-off frequency (fT) of 153 GHz and 288 GHz. The excellent electronic performances indicate the developed 60 nm InAs HEMTs are suitable for high-gain, low noise and low voltage applications. In addition to high frequency RF applications, the evaluations of 60 nm InAs HEMTs for high-speed logic applications have also been demonstrated in this study. The devices show outstanding logic performance in low applied voltage (VDS=0.5 V). The drain induced barrier lowering (DIBL) is 70 mV/V, subthreshold swing (S) is 67 mV/decade, and intrinsic gate delay (CV/ION) is less than 5.0 psec. When comparing to the mature Si technology, the InAs HEMTs exhibit smaller gate delay time. Besides, InAs HEMTs show much higher ION/IOFF performance than the most advanced InSb HEMTs. These results demonstrate that the 60 nm InAs HEMTs have great potential for future high-speed and low-voltage logic applications.