Layer Transfer Technology for Micro-System Integration

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Layer Transfer Technology for Micro-System
Integration
SFR Workshop May 24, 2001 Changhan Yun, Yonah
Cho, Adam Wengrow, and Nathan Cheung Berkeley, CA
2001 GOAL To establish low-temperature
micro-system assembly process for sensor
integration by 9/30/2001.
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Motivation
Detector
Sensor array
Electronics
Interconnects
Battery
Photon emitters
Resonators
Low-Temp assembly process enables integration of
dissimilar microsystems (embedded photon emitter,
energy source, sensors, and electronics)
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LED Array Transfer with Laser Liftoff
2. Laser Liftoff (LLO)
1. Bond receptor onto GaN sapphire
3. Acetone bath
4. Bond to any substrate
Thermal detachment (40C)
Interfacial decomposition
receptor wafer
adhesive
adhesive
handle substrate
LED
Sapphire
Laser beam
Transfer of LED layers from sapphire to silicon
or plastic substrate
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LEDs from Sapphire to Silicon Substrates
LEDs grown on sapphire
Laser-detached GaN surface (bottom surface)
LEDs transferred on silicon
rough In surface underneath
contact pads
Ga residues
receptor wafer
LED
LED
Indium
Silicon
epoxy
Al2O3
LED
LEDs provided by Oriol Inc., Santa Clara, CA
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Blue LED Transferred on Silicon Substrate
From a distance
Under a microscope
probe tip
probe tip
No performance degradation after layer transfer!
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Low-Temperature Silicon Device Layer Transfer
1. H Implantation through MOS devices
2. Wafer Bonding at low temperature
3. Mechanical bending for layer transfer
Device Region
Si donor wafer
Hydrogen peak
H
SiO2
Si handle wafer
10 lbft
Demonstrates low-temperature mechanical cleavage
of Si layer
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Surface Roughness of Mechanically Transferred
Silicon Layer
RMS roughness 5nm
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Concerns Gate Oxide Degradation due to Hydrogen
Implantation
Leakage current measurement through W10mm,
L1.5mm gate oxide
1. Dose Dependence
2. Antenna Ratio (AR) Dependence
50Å
18Å
SILC

• For 50Å Gox, SILC increases with Hydrogen dose
  and AR
• For 18Å Gox, No SILC was detected.

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2002 and 2003 Goals

• By 9/30/2002
• Incorporate light emitting devices on sensor
  wafers
• Demonstrate silicon layer transfer for subsystem
  encapsulation (e.g. batteries)
• By 9/30/2003
• Design interconnection schemes between the
  dissimilar microsystems
• Demonstrate integration of signal and data
  processing systems with photonics and MEMS