MOCVD Technology for LEDopticsjournal.net/upload/post/201106/PT110606000047KgNj.pdf08.10.2010 P 5...
Transcript of MOCVD Technology for LEDopticsjournal.net/upload/post/201106/PT110606000047KgNj.pdf08.10.2010 P 5...
Prof. Dr.-Ing. Michael HeukenVice President Corporate Research and Development
AIXTRON AG,
Fon: +49 (241) 8909-154, Fax: +49 (241) 8909-149,
Email: [email protected]
RWTH Aachen, University of Technology , Templergraben 55,D-52074 Aachen, Germany
MOCVD Technology for LED
08.10.2010P 2
Outline
� Introduction
� Basic MOCVD Technology
� Advantages of Showerhead MOCVD Reactor
� The Planetary Reactor
� LED Processing
� Conclusion
08.10.2010P 3
AIXTRON AG, Aachen
Audi R8 LED Headlight ▪ Nimbus LED Ceiling Light 12 W ▪ LED Street Lighting
Samsung LED-TV 9000 Series ▪ LED Monitor Dell G2410 ▪ LED Toshiba Portégé R500
Example of Products with LEDs
08.10.2010P 4
MOCVD = MetalorganicChemical VaporDeposition
08.10.2010P 5
Compound Semiconductor Systems
� Leading edge design to manufacturing
� Flexible wafer configuration from 2”-300 mm
� Configurable common platform
� Integrated automated solutions
� Customized turn-key solutions
� Proven industry standard & market leader
Planetary Reactor ®
AIX 2800G4, 42x2”
Close Coupled Showerhead ®
CRIUS®, 31x2“
Integrated Concept (IC) System
08.10.2010P 6
MOCVD Source Comparison
Group V Ammonia bottle, capacity: 26,5 kg
Group IIITMGa
Bubbler, 100 g
08.10.2010P 7
gas mixing unitTransport of gases within tubesSwitch by valveControl via MFC, pressurecontroller
For metalorganic sources
Bubbler containing MO source(e.g. TMGa, TMIn, TMAl)
Each bubbler is placed in a thermally controlled bath (Lauda bath)
08.10.2010P 8
Integrated Concept Design
Gas Blending Cabinet
Pump and Run-Vent Cabinet
Reactor Cabinet
08.10.2010P 9
Basic MOCVD Process in Reactor
08.10.2010P 10
Sapphire Substrates: R&D to Production
2"3"
4"
6"
8"
12"
UHB LEDsElectronics
UHB LEDsElectronics
08.10.2010P 11
Cross section of an epitaxial wafer
Cross section of a human hair
Diameter: 100 micronEpitaxial layersgroup III and V elementsthickness: 0.02 micron to 4 micron
Substrate wafernormally madefrom Gallium Arsenide (GaAs) or Indium Phosphide (InP)
350-650micron
2-6 inches(1 micron = 1/1000 mm)
08.10.2010P 12
A cross section of a light emitting diode (LED)
Substrat-Wafer(ca. 5 cm diameter)
+
-
0,00001mm thin layers likeGaN, GaInN
Light
This wafer will beseparated to ca. 10.000 singleLED-Chips
08.10.2010P 13
Advantage of going large
Maximum reactor utilisation
42x2“Area: 100% ref.Yield: 100% ref.
11x4“Area: 101%Yield: 110%*
6x6“Area: 125%Yield:140%*
* 2 mm edge exclusion
Same MOCVD reactor allows up to 40% increase in productivity
08.10.2010P 14
� High Efficiency CoO
� Vertical Flow Designw/o Discontinuity in the Center Yield
� Robust Design Uptime
Showerhead Principle (19x2'')
08.10.2010P 15
Close Coupled Showerhead: The Concept
CCS ���� intrinsic uniform
Carrier and MO into upper showerhead
Carrier and Hydrides into lower showerhead
Ga DistributionMMGa Distribution
radius
Growth-rate
08.10.2010P 16
Thickness uniformity of an LED structure on 200 mm diameter sapphire
� Thickness mappings showing thickness uniformity of σ = 2.6% (with 4 mm edge exclusion).
� Thickness uniformity dominated by high temperature GaN layers.
08.10.2010P 17
Pla
neta
ry R
eact
or®
Pla
neta
ry R
eact
or®
42x2” Nitride Reactor After Fully Loaded Run
Total wafer area 42x2“ = 851cm2
08.10.2010P 18
56x2 inch / 14x4 inch / 8x6 inch / 5x8 inch56x2 inch / 14x4 inch / 8x6 inch / 5x8 inch
Capacity Increase: + 33%*
*compared to AIX2800G4 HT
AIXTRON G5HT: Larger ChamberG5 HT
� Throughput ↑� Large wafers (4”, 6”, 8”)� No particles� Continuous production� Higher yield� Automation� Reduced footprint� Cost of ownership ↓
08.10.2010P 19
Sapphire ~430 µm(0.3deg off-cut from 0001)
4 µm Undoped GaN
2 µm GaN:Si(5x1018)
3x u-InGaN QWs (2.5nm) + GaN:Si(5x1017) QBs (12nm)
2x u-InGaN QWs (2.5nm) + u-GaN QBs (12nm)
40nm AlGaN:Mg
QWs @ ~740°, QBs @ ~860°C
~25nm GaN Nucleation layer
10nm GaN:Mg
900mBar2µm/hr
400mBar4µm/hr
400mBar
266mBar 100 nm GaN:Mg
GrowthPressure
Generic LED Structure
08.10.2010P 20
e electron D donor levelh defect electron / hole A acceptor leveleh exciton / electron-hole pair
Energy ofconduction band
Energy ofvalence band
Conduction band
Valence band
energy gap / band gap
Photon
D D
A A
Recombination between conduction and valance band
E
X
e
h
hh
ee
e
h
eh
1a 1b2a
2b2c
r
2d2e
e
eh
h
Photoluminescence
08.10.2010P 21
EL Test Structure on 6 inch Sapphire
With p-GaN cap added and In contacts
08.10.2010P 22
III-N Based LED Processing
LED on sapphiresubstrate
LED on SiCsubstrate
Epi-Wafer
MESA Litho
1
RIE MESA etch2
p-layern-layer
08.10.2010P 23
3 n-ContactLitho
14n-ContactEvaporation + lift-off
25p-ContactLitho
LED on sapphire substrate LED on SiC substrate
III-N Based LED Processing
08.10.2010P 24
Al 2O3
n-GaN
p-GaN
anode
cathode
transparent contact active zone
p-Contactevaporation+ lift-off
36
LED on sapphire substrate LED on SiC substrate
III-N Based LED Processing
scribing+ dicing 4
7
08.10.2010P 25
Inside the LED…
…the chip
08.10.2010P 26
Design of white LED
Compound Semiconductor, July,2003, (Nichia)
08.10.2010P 27
Conclusion
� Basic MOCVD Technology explained
� Advantages of Showerhead MOCVD Reactor
� Advantages of Planetary Reactor
� Simple LED Processing
08.10.2010P 28
www.aixtron.com
For further information, please contact:
Prof. Dr. Michael HeukenAIXTRON AG, Kaiserstr. 98, D-52134 Herzogenrath
Germany