Leuven May 29, 2006 - IMEC,
Europe's leading independent nanoelectronics and
nanotechnology research institute, has demonstrated
the growth of low-sheet-resistivity AlGaN/GaN high-electron
mobility transistors (HEMTs) on 150mm silicon (Si)
wafers. The process paves the way to low-cost GaN
power devices for high-efficiency/high-power systems
beyond the silicon limits.
The high-quality AlGaN and GaN layers were grown
in IMEC's new 150mm metal-organic chemical vapor-phase
epitaxy (MOVPE) system. This infrastructure extension
allows IMEC to offer access to its AlGaN/GaN epiwafers
in a service mode to laboratories and partner companies.
For the first time ever, excellent uniformity results
have been obtained for the growth of HEMTs on 150mm
Si wafers. HEMT structures with a sheet resistivity
as low as 272±5 O/square and a standard deviation
as small as 1.9% (edge excluded) have been demonstrated.
The process overcomes current problems associated
with the growth of high-quality epitaxial GaN layers
on Si. These problems result from the high lattice
mismatch and the large difference in thermal expansion
coefficient between Si and GaN. An AlGaN buffer layer
has been successfully introduced to provide compressive
stress in the top GaN layer. This, in combination
with an IMEC proprietary in-situ Si 3 N 4 passivation
layer, results in superb HEMT devices on Si.
Due to the lack of commercially available GaN substrates,
GaN heterostructures are nowadays grown mainly on
sapphire and silicon carbide (SiC). Si is a very
attractive alternative due to its very low cost compared
to sapphire and SiC. Other benefits include the acceptable
thermal conductivity of Si (half of that of SiC)
and its availability in large quantities and large
wafer sizes.
The high-quality epitaxial AlGaN and GaN layers
were grown in IMEC's new 150mm metal-organic chemical
vapor-phase epitaxy Thomas Swan Close-Coupled Showerhead
reactor (MOVPE) system, in the framework
of an European Space Agency (ESA) project called
Epi-GaN.
Marianne Germain, director of IMEC's Efficient Power
Program: This reactor is a very valuable extension
of our existing 3x2 system, as it increases both
growth capacity and wafer size (up to 150 mm ). The
infrastructural extension allows IMEC to offer access
to its AlGaN/GaN epiwafers in a service mode to laboratories
and partner companies involved for the development
of their GaN device applications. The results proof
the capability of IMEC to grow HEMT epiwafers with
excellent quality, good uniformity and high reproducibility.
Specifications on epiwafer characteristics available
through this service can be obtained at IMEC on demand.
AlGaN/GaN HEMT epiwafers can be grown on sapphire,
SiC or Si substrates.
Gallium nitride (GaN) has outstanding capabilities
for power, low-noise, high-frequency, high-temperature
operations, even in harsh environment (radiation),
extending considerably the application field of solid-state
devices.
About IMEC
IMEC is a world-leading independent research center
in nanoelectronics and nanotechnology. Its research
focuses on the next generations of chips and systems,
and on the enabling technologies for ambient intelligence.
IMEC's research bridges the gap between fundamental
research at universities and technology development
in industry. Its unique balance of processing and
system know-how, intellectual property portfolio,
state-of-the-art infrastructure and its strong network
of companies, universities and research institutes
worldwide position IMEC as a key partner for shaping
technologies for future systems.
As an expansion of its wireless autonomous microsystems
research, IMEC has created a legal entity in the
Netherlands. Stichting IMEC Nederland runs activities
at the Holst Centre, an independent R&D institute
that develops generic technologies and technology
platforms for autonomous wireless transducer solutions
and systems-in-foil.
IMEC is headquartered in Leuven, Belgium, and has
representatives in the US, China and Japan. Its staff
of more than 1450 people includes more than 500 industrial
residents and guest researchers. In 2005, its revenue
was EUR 197 million. Further information on IMEC
can be found at www.imec.be .
Contact :
Katrien Marent, IMEC Corporate Communications, T:
+32 16 28 18 80, katrien.marent@imec.be
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