Details

Autor(en) / Beteiligte

• Guan, He
• Shen, Guiyu
• Gao, Bo
• Zhang, Hao
• Wang, Yucheng
• Wang, Shaoxi

Titel

A Study on the Optimized Ohmic Contact Process of AlGaN/GaN-Si MIS-HEMTs

Ist Teil von

• IEEE access, 2021, Vol.9, p.9855-9863

Ort / Verlag

Piscataway: IEEE

Erscheinungsjahr

2021

Quelle

EZB Free E-Journals

Beschreibungen/Notizen

• AlGaN/GaN-Si based MIS-HEMTs are considered as the popular candidates for application in the 5G communication system due to their competitive characteristics and low cost. Ohmic contact, as an important fabrication process, significantly affects the performance of the device. In this study, the ohmic contact process, including the SiN passivation layer etching, surface treatment, and barrier layer etching, was studied in detail in order to effectively optimize the device performance. It is observed that the sample with the SiN passivation layer etched by the magnetic neutral loop discharge (NLD) resulted in a lower contact resistance as compared to the reaction ion etching (RIE). The sample surface treated with the O plasma and pickled in the HCl:H2O = 1:10 liquid could effectively remove the pollutants and oxides from the surface, thus, correspondingly presenting a lower ohmic contact resistance as compared to the N2 plasma. Meanwhile, an optimum etching depth was developed with the ICP process for 6 min with an etching speed of 1.6 nm/min. A contact resistance of <inline-formula> <tex-math notation="LaTeX">0.76~\Omega \cdot \text {mm} </tex-math></inline-formula> and square resistance of 274.63 ohm/sq were observed under the above-mentioned optimized ohmic contact process. The AlGaN/GaN-Si MIS-HEMT with gate length of <inline-formula> <tex-math notation="LaTeX">0.5~\mu \text{m} </tex-math></inline-formula>, gate-source space of <inline-formula> <tex-math notation="LaTeX">1~\mu \text{m} </tex-math></inline-formula>, gate-drain space of <inline-formula> <tex-math notation="LaTeX">2.5~\mu \text{m} </tex-math></inline-formula>, and gate width of <inline-formula> <tex-math notation="LaTeX">100~\mu \text{m} </tex-math></inline-formula> was fabricated using the optimized process. A saturation current density of 794.30 mA/mm and the maximum transconductance of 16.86 mS were observed. The findings in this study provide the experimental basis for the manufacturing of AlGaN/GaN-Si based MIS-HEMTs for RF applications.