Fabrication and characteristics of 0.12 µm AlGaAs/InGaAs/GaAs pseudomorphic HEMT using a silicon nitride assisted process
Jong-Won Lim; Ho-Kyun Ahn; Hong-Gu Ji; Woo-Jin Chang; Jae-Kyoung Mun; Haecheon Kim; Jong-Won Lim; High Speed SoC Research Department, Basic Research Lab, Electronics and Telecommunications Research Institute, Daejeon 305-350, Korea; Ho-Kyun Ahn; High Speed SoC Research Department, Basic Research Lab, Electronics and Telecommunications Research Institute, Daejeon 305-350, Korea; Hong-Gu Ji; High Speed SoC Research Department, Basic Research Lab, Electronics and Telecommunications Research Institute, Daejeon 305-350, Korea; Woo-Jin Chang; High Speed SoC Research Department, Basic Research Lab, Electronics and Telecommunications Research Institute, Daejeon 305-350, Korea; Jae-Kyoung Mun; High Speed SoC Research Department, Basic Research Lab, Electronics and Telecommunications Research Institute, Daejeon 305-350, Korea; Haecheon Kim; High Speed SoC Research Department, Basic Research Lab, Electronics and Telecommunications Research Institute, Daejeon 305-350, Korea
Журнал:
Semiconductor Science and Technology
Дата:
2004-12-01
Аннотация:
We report the fabrication of a 0.12 µm T-gate with a silicon nitride assisted process. A two-step etch process was performed to define the gate footprint in the SiN<sub>x</sub>. The SiN<sub>x</sub> was etched either by dry etching (RIE) alone or by using a combination of wet and dry etching. The gate recessing was done in two steps including a wet etching for the removal of the damaged surface layer and a dry etching for the narrow recess. We have seen that the increases of the cut-off frequency f<sub>T</sub> and the maximum oscillation frequency f<sub>max</sub> are 39% and 16%, respectively. This was believed to be due to a remarkable decrease of the gate-source and gate-drain capacitances by 25% and 18.3%, respectively. The improvement in RF performance can be understood in terms of the decrease in parasitic capacitances due to SiN<sub>x</sub> and the gate recess etching method.
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