Abstract
We optimized a silicon nitride (SiNx) passivation process using a catalytic-chemical vapor deposition (Cat-CVD) system to suppress the current collapse phenomenon of AlGaN/GaN-on-Si high electron mobility transistors (HEMTs). The optimized Cat-CVD SiNx film exhibited a high film density of 2.7 g/cm3 with a low wet etch rate (buffered oxide etchant (BOE) 10:1) of 2 nm/min and a breakdown field of 8.2 MV/cm. The AlGaN/GaN-on-Si HEMT fabricated by the optimized Cat-CVD SiNx passivation process, which had a gate length of 1.5 μm and a source-to-drain distance of 6 μm, exhibited the maximum drain current density of 670 mA/mm and the maximum transconductance of 162 mS/mm with negligible hysteresis. We found that the optimized SiNx film had positive charges, which were responsible for suppressing the current collapse phenomenon.
Highlights
AlGaN/GaN high electron mobility transistors (HEMTs) are promising candidates for microwave power amplification and power switching applications owing to their excellent characteristics, such as wide energy bandgap, as well as high breakdown field, mobility, and saturation velocity [1,2]
Various deposition systems have been utilized for SiNx film deposition, including plasma-enhanced chemical vapor deposition (PECVD), inductively coupled plasma CVD (ICP-CVD), and low-pressure
We suggest that the catalytic-chemical vapor deposition (Cat-CVD) SiNx passivation process developed in this work is very promising for suppressing the current collapse phenomenon of GaN devices
Summary
AlGaN/GaN high electron mobility transistors (HEMTs) are promising candidates for microwave power amplification and power switching applications owing to their excellent characteristics, such as wide energy bandgap, as well as high breakdown field, mobility, and saturation velocity [1,2]. Significant progress has been achieved in the past decades, surface trapping and its related current collapse phenomena remain critical for device performance and reliability. The current collapse phenomenon that degrades the dynamic characteristics of the device contributes significantly to performance instability and reliability of the device. The current collapse phenomenon can be mitigated by surface passivation along with a field plate where the dielectric passivation process is carefully optimized [3]. These systems employ high-power plasma and/or a high deposition temperature causing plasma damage at the surface and thermal budget problems. A catalytic CVD (Cat-CVD) process was proposed to solve these problems. We determined high-quality SiNx deposition process conditions using a Cat-CVD system. It was found that the optimized SiNx passivation process was very effective in reducing.
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