Engineering a Unified Dielectric Solution for AlGaN/GaN MOS-HFET Gate and Access Regions

Typically GaN metal-oxide-semiconductor heterojunction-field-effect transistors (MOS-HFETs) have used two separate dielectrics for the gate and access regions. However, as this article shows, with proper gate-stack engineering, a unified dielectric solution can be achieved for the transistor. HfO 2...

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Bibliographic Details
Published in:IEEE transactions on electron devices 2020-03, Vol.67 (3), p.881-887
Main Authors: Azam, Faisal, Tanneeru, Akhilesh, Lee, Bongmook, Misra, Veena
Format: Article
Language:English
Subjects:
AlGaN/GaN
Aluminum gallium nitride
Aluminum gallium nitrides
atomic layer deposition (ALD)
Atomic layer epitaxy
current collapse
Current leakage
Dielectrics
Field effect transistors
Gallium nitrides
Hafnium oxide
HEMTs
Heterojunctions
HfO
high electron mobility transistor (HEMT)
High temperature
high-<italic xmlns:ali="http://www.niso.org/schemas/ali/1.0/" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">k
high-temperature reverse bias (HTRB)
hydroxyl
interface
Logic gates
Metal oxides
MODFETs
MOS-HFET
oxidant
Oxidizing agents
Ozone
reliability
Semiconductor devices
Threshold voltage
Transconductance
traps
Wide band gap semiconductors
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Summary:Typically GaN metal-oxide-semiconductor heterojunction-field-effect transistors (MOS-HFETs) have used two separate dielectrics for the gate and access regions. However, as this article shows, with proper gate-stack engineering, a unified dielectric solution can be achieved for the transistor. HfO 2 dielectrics were deposited by atomic layer deposition (ALD). Two types of oxidants were investigated, namely, water (H 2 O) and ozone (O 3 ). It was found that MOS-HFETs with O 3 oxidant yielded lower threshold voltage (VTH) shifts, higher maximum drain current (IDS,max) of 340 mA/mm, 20% lower ON-resistance (RON), higher peak transconductance at 112.66 mS/mm, lower hysteresis, and lower gate leakage (5.4 × 10 -6 A/cm 2 ) compared to water oxidant based MOS-HFETs with IDS,max of 240 mA/mm, 81.38 mS/mm peak transconductance, and 1.7 × 10 -4 A/cm 2 gate leakage. DC/RF dispersion tests showed MOS-HFETs with O 3 oxidant had -200x better current collapse recovery. Temperature characterization and reliability test results, such as high-temperature reverse bias (HTRB), are published for the first time on ALD-HfO 2 /AlGaN/GaN MOSHFETs using tetrakis(dimethylamino)hafnium (TDMAH) and O 3 precursor. Using an ozone oxidant provided more stability (i.e., less variability in RON and VTH) as a function of temperature. Finally, when devices were electrically stressed in the OFF-state, the HTRB test showed minimal VTH drift (
ISSN:0018-9383
1557-9646
DOI:10.1109/TED.2020.2969394