Transcript MORGaN training opportunities

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Materials for Robust Gallium Nitride
Michał A. Borysiewicz,
Eliana Kamińska, Anna Piotrowska
Institute of Electron Technology
Warsaw, Poland
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Outline
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Introduction to the MORGaN project
Overview of each topic + results
Training opportunities
Contact information
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Introduction
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MORGaN- Materials for Robust Gallium Nitride
Robust – capable of performing without failure
under a wide range of conditions
Merriam-Webster Dictionary
GaN – wide band-gap semiconductor
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Why GaN?
• Advantages over traditional semiconductors
– Thermal & chemical stability (operation > 1000ºC)
– High breakdown fields (DC to microwave > 5MVcm-1)
• Potential for technology improvements
– Power electronics
– Harsh environment sensors
• Drawbacks
– Limited wafer availability
– Material quality problems
• Defects & intrinsic material strain
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Key objectives of the Project
Develop GaN sensors & microwave
transistors for harsh environments
• Materials
– New nitride growth techniques
– Novel diamond composite substrates
– Diamond passivation
• Processing
• Packaging
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MORGaN topics
1.) III-V materials
• Improved GaN films
– Low stress and low defect density
– Optimisation of InAlN/GaN heterostructures
2.) Diamond-based materials
• Innovative diamond-based composite substrates
• Nanocrystalline diamond coatings for passivation &
heat removal
3.) Harsh environment devices
• High power electronic devices
• Sensors for harsh environments
4.) Packaging and metallisation
• For harsh environment applications.
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MORGaN consortium
UK
GERMANY
SWEDEN
POLAND
CZECH
REPUBLIC
SLOVAKIA
FRANCE
HUNGARY
AUSTRIA
SWITZERLAND
24 partners; 11 nations
Project lead organisation: Alcatel-Thales III-V Labs
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GREECE
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Topics & results
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1.) III-V materials
Objectives
– New substrates for low defect density GaN
• Polycrystalline diamond/Si sandwich hybrid substrates
• Compliant heterostructures for growing GaN film
– Growth optimisation of InAlN/GaN heterostructures
• Harsh environment electronic & sensing applications
Novel approaches
– New InxAl1-xN/GaN heterostructures
• Lower intrinsic mechanical stress
• Minimises material degradation
• Originally developed in FP6 www.ultragan.eu
– “Nano-columns" technique
• Developed at the University of Bath
• Used to grow low defect density GaN film.
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MORGaN technology 1
Nano-columns
Seeded nano-columns
a)
Arbitrary
substrate
Seed layer
b)
Near defect-free epi-layer
(formed by coalescence of nano-columns)
c)
Nano-columns distort to
accommodate strain and deflect
dislocations
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2.) Diamond-based materials
Diamond
– Highest thermal conductivity of any solid
~2000Wm-1K-1 in high quality CVD diamond
– Potentially the ultimate substrate for high temperature & extreme
power applications
GaN alloys
– Impressive power handling capability
Objectives
MORGaN will develop diamond/ GaN hybrids
– Thermal
behaviour of diamond
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– Electrical efficiency of GaN
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MORGaN technology 2
Nano-crystalline diamond coating
• Diamond overgrowth for thermal management
• Large area diamond overgrowth
– Polycrystalline diamond deposition by hot-filament CVD
Typical HEMT structure
Heat sink T=20°C
20m
Diamond
Simulation of performance of HEMTs/
Al2O3 and SiC
Sapphire Sub.
Metalization
Active Device Structure
Buffer
Substrate
SiC Sub.
Diamond
(Sapphire Sub.)
Diamond (SiC Sub.)
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3.) Harsh environment devices
“External harsh environment”
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Extreme heat
Pressure
High electric fields
Chemically aggressive substances.
“Internal harsh environment”
• Power dissipation from large current flow at high
bias
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3.) Harsh environment devices
• Cantilever pressure sensor
• Drumskin pressure sensor
• 1kW 2GHz power bar
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MORGaN technology 3
Cantilever pressure sensor
• Based on a double cantilever design chip
‒ One cantilever deflected by a probe attached to a flexible membrane
‒ Second cantilever – reference for temperature compensation
• Signal – due to the piezo-electric effect in the GaN under strain
Sensor chip
Solder
pads
optical microscope image of
a GaN-based cantilever
cantilever deflection
measured using optical
interferometry
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Temperature
sensor
Double
cantilever
structure
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MORGaN technology 3
Drumskin pressure sensor
Alternative design: HEMT sensor directly integrated in a diaphragm
• Diaphragm used for the detection of pressure (100 – 1000 atm)
• Membrane strain transferred to a GaN-based sensing device
• Circular HEMT as a pressure sensing device
Advantages to this design:
• Simple C-HEMT fabrication and integration on membrane structure
• Parasitic gate leakage current significantly suppressed
• A large gate area easily achieved.
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MORGaN technology 3
Towards a 1kW 2GHz power bar demonstrator
250W power chip specified and
designed
• 90 fingers (each 400µm long)
• Die size 1mm x 5mm
• Four chips be co-packaged to build a 1kW
device
Test chips manufactured and tested
• DC and CW characterisation performed
• Very good yield obtained on power device
and power die
• State-of-the-art results! 6.6 W/mm and 70%
PAE @3.5GHz
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Pout (dBm), PAE (%) & Gp (dB)
• 2 mm power cells
70
PAE
60
50
40
30
Pout
20
Gp
10
0
0
5
10
15
20
Pin (dBm)
25
30
35
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4.) Packaging and metallisation
Objectives
To develop packaging and metallisation solutions that are:
– Thermally stable and compatible
– Chemically stable
MORGaN novel approaches
– Advanced 3D ceramic packaging
– New metallisation techniques
• Emerging technology of MN+1ANX alloys
– Ceramic/ metal systems for high temperature
applications
– Novel layer package manufacture techniques
• Permit very complex geometrical package and
interconnect structures
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MORGaN technology 4
Layer manufacturing
Novel process to produce steel
parts using ink-jet technology
– Process uses a fine stainless steel
powder (316L)
– Sintered to full density
– Other steels & metals (e.g. Ti) also
possible
– Resolution c. 20m (x,y); 40m (z)
– Surface finish c. 4m
Large geometric freedom
– Complex shapes for novel
packaging possible.
Dual purpose housings for either
cantilever chip or drumskin device
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Training opportunities
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MORGaN training opportunities
• MORGaN offers many training opportunities
– Ph.D. students
• Advanced and emerging knowledge on thesis topics
• Wider technological context
– Established researchers and technologists
• Wide scope for new skills & information
• Residential course, May’10, Bratislava
– Advanced instruction on core MORGaN topics
• Workshop
– To be held in the second half of the project
• Research visits between MORGaN partners
– Extended research visits (1-12 weeks duration)
– Postgraduate student/ experienced researcher level.
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Contact information
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MORGaN contact information
For more information:
– Project leader
• Sylvain Delage; Alcatel-Thales III-V Lab
[email protected]
– Dissemination
• Bruce Napier; Vivid Components
[email protected]
– Website : www.morganproject.eu
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