High Speed sSi Integrated Circuits on Plastic Substrates

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High Speed µs-Si Integrated Circuits on Plastic
Substrates
Objectives
Technical Approach
Process to build circuits

• To generate a high performance Si transistor
  with a top gate geometry on flexible plastic
  substrates
• To build high speed µs-Si integrated circuits on
  plastic

PECVD growth SiO2
doped
undoped
Box
SOI
PDMS transfer
S-D open metallization
Isolated us-Si
Polyimide precursor
thin kapton
Technical Accomplishments
High speed µs-Si integrated circuits

• Developed transfer process using polyimide
  precursor to improve the properties of device
• Built high performance transistor with a top
  gate geometry using polyimide and solid source
  doping
• Optimized the process to build circuits on thin
  Kapton film

Freq8.2MHz
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High Speed µs-Si Integrated Circuits on Plastic
Substrates
Jong-Hyun Ahn
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Content
1. Introduction 2. µS-Si transistor and Nmos
Ring Oscillator 2.1 µS-Si transistor
2.1.1 Overall process 2.1.2. Optimization
procedures 2.1.3. Results
2.2 Circuit 2.2.1 Circuit Design
Building 2.2.2 Results 3. Conclusion
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Applications of Flexible electronics
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Semiconductor Materials for Macroelectronics

• a-Si
• - low carrier mobility
• poly-Si
• - high cost and complex process
• 
  IEEE
  Electron Device Lett. 19, 306 (1998)
• Conventional Organic
• - low carrier mobility Adv.
  Mater. 16, 2097 (2004)
• - weak long-term durability J.
  Appl. Phys. 96, 2080 (2004)
• Phys. Status Solidi A 201, 1302
  (2004)
• Single Crystal Si
• - high carrier mobility
• - stable electrical properties

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Microstructured (µs)-Si
Microstructured (µs)-Si for High Performance
Macroelectronics 1) High performance 2)
Large area, flexible electronic devices
Appl. Phys. Lett 84, 5398 (2004) Nano letter, 4,
1953 (2004)
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Process to build µS-Si transistor with top gate
Undoped area
Doped area
µs-Si
Box
PDMS transfer
PECVD SiO2 Growth S-D Open
G
S
D
Polyimide precursor
Thin Kapton
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Optimization procedure
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Glue Materials
Lewis acid photogeneration
SU8 Epoxy
Cationic polymerization
Polyamicacid, Polyimide Precursor
250?,1h
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Top Gate Si Transistor on Plastic
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Comparison between Measured Data and Theoretical
Data

• Using Small-signal Model (Simplified Meyer Model)
  to characterize
• Unity-current Frequency, fT, in terms of
  transconductance (gm) and Capacitance (CGS and
  CGD).
• Transconductance can be measured directly from IV
  measurements,
• and Capacitances can be model
  theoretically.

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High Frequency Measurement Setup
Keithley 2602 DC Source
Agilent ENA E5062A
Control Software Advanced Deisng System
Bias TEE
CASCADETM RF-1 Microwave Probing Station
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Transistor- High Frequency Response
3mm Channel 2mm Overlap distance
VGS 1.8V VDS 2.0V
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Transistor- Bending test
?
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Transistor- Bending test
L5? L02?
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Ring Oscillator
NMOS type inverter
Nmos-loaded 5-stages ring oscillator
n the number of stages td the delay of each
stage
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Frequency of Ring Oscillator
PSPICE simulations of oring oscillator circuit
L5um / Lo5um
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Process to build Circuit
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Circuit layout
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5 Stage NMOS Ring Oscillator
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Inverter - Bending test
?
L 5um/ Lo 2um (W200um, WI30um)
?
L 5um / Lo 5um (W200um, WI30um)
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Oscillator - Bending test
?
compression
tension
7.4MHz
8.8MHz
8.2MHz
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Conclusion

• Printed high performance Si top gate transistor
  with PECD SiO2 as the
• gate dielectric on plastic substrates through
  optimized procedures.
• Build 8.2MHz ring oscillator with on plastic.

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Acknowledgements
Prof. John Rogers Hoonsik Kim Keon-Jae
Lee Zhengtao Zhu Etienne Menard Si team members