DC, RF and noise performance of InAs/AlSb HEMTs with in situ CVD SiNx-film for early-protection against oxidation
Journal article, 2013

A new method for avoiding air exposure of the mesa-floor during processing of shallow-mesa InAs/AlSb HEMTs is reported. The method is based on the in situ chemical vapor deposition (CVD) of a SiNx-film, right after the shallow-mesa dry-etch process. The in situ CVD method allows also growing a dielectric film up to five times thicker than in previous reports of similar early-protection approach. Devices featuring a 25 nm SiNx-film enabled by the in situ CVD method are compared to devices based on a previously developed process, where the mesa floor is protected by a 2 nm SiNx-film deposited by ex situ reactive sputtering (RS). Microscopy observations revealed that the new process is more robust, ensuring a long-term stability against oxidation. DC, RF and noise performance were measured for 110 nm gate-length HEMTs. Devices based on the CVD process demonstrated higher peak transconductance (+13%), elevated I-on/I-off ratio (factor 4.7) and one order of magnitude lower gate current leakage. The cut-off frequency f(T) and the maximum oscillation frequency f(max) at a drain-source voltage of 0.3 V increased up to 175 GHz (+20%) and 130 GHz (+18%), respectively. Moreover, the extracted minimum noise figure for the InAs/AlSb HEMT using the in situ CVD early-protection was 1.4 dB at 6 GHz, instead of 2.3 dB for the RS based devices.

Chemical vapor deposition (CVD)

Passivation

Oxidation

Leakage-current

InAs/AlSb high electron mobility transistor (HEMT)

In situ

Author

Giuseppe Moschetti

Chalmers, Microtechnology and Nanoscience (MC2), Microwave Electronics

Eric Lefebvre

Chalmers, Microtechnology and Nanoscience (MC2), Microwave Electronics

Martin Fagerlind

Chalmers, Microtechnology and Nanoscience (MC2), Microwave Electronics

Per-Åke Nilsson

Chalmers, Microtechnology and Nanoscience (MC2), Microwave Electronics

L. Desplanque

University of Lille

X. Wallart

University of Lille

Jan Grahn

Chalmers, Microtechnology and Nanoscience (MC2), Microwave Electronics

Solid-State Electronics

0038-1101 (ISSN)

Vol. 87 85-89

Subject Categories

Electrical Engineering, Electronic Engineering, Information Engineering

DOI

10.1016/j.sse.2013.06.008

More information

Created

10/7/2017