DC, RF and noise performance of InAs/AlSb HEMTs with in situ CVD SiNx-film for early-protection against oxidation
Artikel i vetenskaplig tidskrift, 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

Författare

Giuseppe Moschetti

Chalmers, Mikroteknologi och nanovetenskap (MC2), Mikrovågselektronik

Eric Lefebvre

Chalmers, Mikroteknologi och nanovetenskap (MC2), Mikrovågselektronik

Martin Fagerlind

Chalmers, Mikroteknologi och nanovetenskap (MC2), Mikrovågselektronik

Per-Åke Nilsson

Chalmers, Mikroteknologi och nanovetenskap (MC2), Mikrovågselektronik

L. Desplanque

University of Lille

X. Wallart

University of Lille

Jan Grahn

Chalmers, Mikroteknologi och nanovetenskap (MC2), Mikrovågselektronik

Solid-State Electronics

0038-1101 (ISSN)

Vol. 87 85-89

Ämneskategorier

Elektroteknik och elektronik

DOI

10.1016/j.sse.2013.06.008