應用於低電壓無線通訊之離子佈植砷化鎵功率金屬半導體場效電晶體之研究

Abstract

本實驗的目的在於製造應用於低電壓無線通訊之離子佈植砷化鎵功率 金屬半導體場效電晶體 (Power MESFET). 文中詳述了各個製程步驟的技 術,並藉著精確的製程控制達成優良的元件特性以及高產率. 此 MESFET 元件的直流特性良好, 1 um * 1 mm 的元件具有 300 mA/mm 的最 大電流密度 (maximum current density,在汲極電壓為 +0.5 V時測得) 和高達 29.5 V 的閘極-汲極崩潰電壓 (gate-to-drain breakdown voltage),最大互導率達 135 mS/mm,夾止電壓(pinch-off voltage) 為 -2.2 V,飽和電壓 (effective knee voltage) 低於 0.3 V.1 um * 10 mm 的元件之飽和電流為 2.3 A. 本論文亦論及了在 3.0 V 及 4.6 V 的 汲極電壓下,元件在 900 MHz 操作時的微波功率特性.在 3.0 V 操作下 1 um * 10 mm 尺寸的元件具有高達 1 W 的最大輸出功率(maximum output power density),而輸出功率密度 (maximum output power dinsity) 高達 100 mW/mm,此時功率效益 (power-added efficiency) 高達 60.1 %.針對低電壓無線通訊應用,在已被報導的 MESFET 中,我們的元件具有最 大的輸出功率密度. 實驗的結果顯示這種 MESFET 能提供大的輸出功 率.在下一代的無線通訊應用方面具有極大的發展潛力. A ion implanted GaAs power MESFET for low voltage wireless communicationhas been developed. Detail processing techniques including ion implantation, annealing, mesa isolation, ohmic contact, gate recess, gate formation, passivation, airbridge and backside processing were described in this thesis.Proper process control ensured good device performance and high yield. The DC characteristics of the MESFET were measured. The 1 um * 1 mm deviceexhibited a maximum current density of 300 mA/mm (at VGS=+0.5 V) with a gateto drain breakdown voltage of 29.5 V. The maximum transconductance of thedevice was 135 mS/mm and the pinch-off voltage was -2.2 V. The knee voltage was 1.4 V and the effective knee voltage was as low as 0.3 V. The 1 um * 10 mmdevice exhibited a saturation current of 2.3 A. The thesis also reports the microwave power performance of the device at 900 MHz and operated at a DC drain bias of 3.0 V and 4.6 V respectively. The power performance for the 1 um * 10 mm device demonstrated a maximum output power of 1 W with a 60.1 % power- added efficiency (PAE) under 3.0 V drain biased condition. Maximum output power density was 100 mW/mm. This is thehighest output power density of MESFETs reported for low voltage wireless communication applications. This results indicate that the MESFET developed can provide large outputpower. The ion implanted GaAs MESFETs is a potential candidate for the nextgeneration wireless communication applications.