非退火式的鈦/鉑/金歐姆接觸之增強型砷化銦通道高電子遷移率電晶體應用於低耗能邏輯元件之特性研究

Abstract

隨著元件尺寸的縮小，半導體產業在摩爾定律上已經遇到瓶頸，其中關鍵在於如何讓元件在漏電流不增加的情況下，使導通電流最大化。相較於矽，三五族複合物半導體有較高的載子遷移率且其基板具有半絕緣特性，這些材料性質結合能帶設計、磊晶成長設計和不同的製程能夠提升元件特性。近年來，由於三五族砷化銦鎵材料的高電子遷移率以及高電子遷移率電晶體優異的能帶設計，高銦含量的砷化銦鎵通道高電子遷移率電晶體已在高速度及低耗能邏輯應用方面展現極大潛力。 在此研究中，成功的製作出六十奈米閘極線寬的增益型砷化銦通道量子井高電子遷移率電晶體，並透過薄阻障層與白金閘極掘入，及非退火式的鈦/鉑/金歐姆接觸，使元件於高速度及邏輯應用方面展現優異的特性。此研究評估在低操作偏壓下使用非退火式的歐姆接觸，元件展現了較佳飽和電流、較高的電流增益截止頻率(377.7 GHz)和功率增益截止頻率(214 GHz)。而在邏輯應用方面，發現在低偏壓下(VDS = 0.5 V)元件也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30 mV/V，而次臨界擺幅也是相當低的69 mV/decade，此外，其開關電流比值大於104。這些研究結果可以證實六十奈米增益型砷化銦通道量子井高電子遷移率電晶體極有潛力作為未來高速邏輯電晶體的使用。

Semiconductors industry faces significant difficulties as it endeavor to extend Moore’s law through aggressive process scaling. One of the key issues lies in maximizing the device on-current, while suppressing the leakage currents. In general, III-V compound semiconductors have significantly higher intrinsic mobility than silicon and the substrates are semi-insulating. These material properties combing with band gap engineering, epitaxial layer growth technique and process technologies result in the devices with excellent performance. Recently, High indium content InGaAs-based High electron mobility transistors (HEMTs) are particularly promising for future high-speed and ultra-low power logic applications because of the excellent electrical properties of InxGa1-xAs material and the superior band-gap design of HEMTs. In this study, a 60-nm enhancement mode (E-mode) In0.65Ga0.35As/InAs/ In0.65Ga0.35As composite-channel HEMTs is fabricated, which using thin barrier, gate sinking process and non-annealed ohmic process to yield excellent performance for high-speed and logic applications. The device demonstrated a high cut-off frequency of 377.7 GHz and maximum oscillation frequency of 244GHz. For logic applications, when biased at VDS = 0.5 V, it also exhibited excellent performance including the drain induced barrier lowering of 30 mV/V, minimum sub-threshold swing of 69 mV/decade, and ION/IOFF higher than 1.2 × 104. These results demonstrate that the E-mode In0.65Ga0.35As/InAs/In0.65Ga0.35As HEMTs have great potential for future high-speed and low-power logic applications.