U.S. -KOREA Forums on Nanotechnology
CURRENT STATUS OF
NANOIMPRINT LITHOGRAPHY
DEVELOPMENT IN CNMM
February 17th 2005
Eung-Sug Lee,Jun-Ho Jeong
Korea Institute of Machinery & Materials
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Outlines
I. PROCESS TECHNOLOGY
Single Step UV-NIL
UV-NIL using an Elementwise Patterned Stamp (EPS) in a
Low Vacuum or Atmospheric Environment
UV-NIL for Uniform and Minimum Residual Layer
Step and Repeat UV-NIL
High Throughput Step-and-Repeat UV-NIL using a Large Area
Stamp
II. APPLICATION TECHNOLOGY
Nano Wire Grid Polarizer
Photonic Band Gap Device
III. TOOL TECHNOLOGY
Single-Step UV-NIL Tool
IV. SUMMARY
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Process
technology
Single step UV-NIL
UV-NIL using a elementwise patterned
stamp (EPS) in a low vacuum
environment
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Schematic of UV nanoimprint lithography (UV-NIL)
stamp
UV curable
resin
substrate
press
stamp
cure
remove
stamp
RIE
illuminate
with UV light
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Characteristics of UV-nanoimprint lithography
Thermal type
NIL
Resin
Stamp
Thermoplastic polymer
UV type
NIL
UV curable resin
Silicon, Nickel
Quartz, glass
(transparent)
Processing
temperature
> Tg
(glass transition
temperature)
Room temperature
Processing
pressure
High ( ~ 30 bar)
Low (~ 1 bar)
material
Advantages for
mass production, multi-layer process,
and step & repeat process
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Recent studies on NIL
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Nanoimprint lithography- Prof. Chou, Princeton University, 1995
Imprint
(Press stamp)
Heating
(150oC-250oC)
Stamp
Resist
Substrate
Remove stamp
RIE
Imprint mold with
10nm
diameter pillars
10nm diameter holes
imprinted in PMMA
10nm diameter metal
dots fabricated by NIL
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UV Light
Recent studies on NIL
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UV-Imprint lithography
Self-leveling
flexure
Template (contains
circuit pattern)
UV curable
solution
dispensed by
drops
Wafer
University of Texas at Austin (Sreenivasan et al.), 1999
Molecular Imprints Inc.
Step & Flash Imprint Lithography (SFIL)
UV blanket expose
13 mm or 25 mm
Quartz Template
Release Layer
Planarization Layer
Substrate
HIGH resolution, LOW
aspect-ratio relief
Residual Layer
Monomer
HIGH resolution, HIGH
aspect-ratio feature
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Motivations
Step & repeat type UV-NIL using a small area (≤ 1 in.) stamp
⇒ Low-throughput
(The imprint time is 2-3 minutes for each field and 10-20 minutes for a 4 in.
wafer)
Single step UV-NIL using a large-area stamp in a medium/ highvacuum environment
⇒ requires a vacuum-compatible system and UV curable resin
For high-throughput manufacturing
⇒ We have developed new UV-NIL processes using a large-area stamp in
a low-vacuum or atmospheric environment
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Elementwise patterned stamp
In a low vacuum-pressure or atmospheric environment
Single-step UV-NIL
using a large area flat stamp
Step-and-repeat UV-NIL
using a small stamp
Advantages
Advantages
- High-throughput
UV-NIL using
EPS
- Low-cost stamp
- Prevention of air
entrapment
Elements with nanopattern
- Easy release
- Precise alignment for
each field
Channel
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Elementwise patterned stamp
Stamp
Element stamp
A
A
Nanostructues
Element
Channel
Cross section
AA
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UV-NIL process using EPS
Step I: Multi-dispensing
Step II: Pressing EPS
Nozzle
Droplets
Press
Patterned
elements at top
Turning EPS round
Wafer below stamp
EPS
Patterned elements
at bottom
Producing vacuum (air out)
Step IV: Releasing EPS
Step III: UV exposure
UV
Separate
Imprinted element
Wafer
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UV-NIL process using EPS
Equipment- EVG620-NIL
UV lamp
- Use 4 in. wafer
- Vacuum hard contact mode
Microscope
Parameters
Pressure
800mbar
Exposure time
60 sec
Exposure intensity
36 mW/cm2
UV curable resist
- PAK01(viscosity = 7 cps)
Wafer
chuck
Alignment
stage
Anti-vibration
table
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UV-NIL process using EPS
Residual layer thickness (RLT)
4 in. wafer with 9 successfully
imprinted elements
distribution
13 mm
C
A
C
B
A
B
B
B
A
A: 90 - 100 nm
B
C
B: 60 - 70 nm
C: 50 - 60 nm
A
C
Droplets
c
b
a: 70 - 80 nm
b
Planarization layer
a
b
b: 50 - 60 nm
c: 40 - 50 nm
Imprinted element
c
10 mm
Air flow direction
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UV-NIL process using EPS
Imprint results
70 nm lines
50 nm lines
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Process
Technology
Single Step UV-NIL
UV-NIL using EPS and Additive
Pressurization in an Atmospheric
Environment
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Single-step UV-NIL in an atmospheric environment
Î Elementwise Patterned Stamp (EPS): avoid air entrapment
Î Additive Pressurization: uniform residual layer thickness
dispenser
element
(field)
EPS
pressurization
5 droplets/field
air out
air pressure
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Single-step UV-NIL in an atmospheric environment
Dispensing
Press
secondary resist flow
additive pressurization
1st pressurization
2nd pressurization
Air pressure
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Imprint results
90-100 nm
60-70 nm
50-60 nm
residual layer thickness
planarization layer (60 nm)
50 nm lines
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Process
Technology
Step and Repeat UV-NIL
High Throughput Step-and-Repeat
UV-NIL using a Large Area EPS
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Step-and-repeat UV-NIL in an atmospheric environment
Effective
elements
Imprint I
Imprint IV
Imprint II
Imprint III
Patterned elements
at bottom
Air
Selectively dispensing
Step-and-repeat imprint
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Step-and-repeat UV-NIL in an atmospheric environment
Step I
Transparent
backplate
EPS
Wafer
chuck Wafer Resin droplet
Step IV
UV
Dispensing nozzle
Gas
Press
Step II
Step V
Imprinted element
Chamber
Press
Step III
Step VI
Gas
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Step-and-repeat UV-NIL in an atmospheric environment
80 nm lines with a 110 nm pitch
Residual layer
Planarization layer
50 nm lines
80 nm lines with a 110 nm pitch
8 in.
80 nm lines with a 110 nm pitch
80 nm lines with a 110 nm pitch
50 nm lines
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Application
Technology
Nano Wire Grid Polarizer
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-KOREA Forums
on Nanotechnology
Nanoimprint
Lithography
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Advantages of Nanoimprint Lithography
High resolution
Low tool cost
High throughput
Simple process
Process Flow (Nano Wire Grid Polarizer)
Aluminum
Deposition
Demolding
Resist Coating
Residual Layer
Removing
Imprint
(Heat & Pressure)
Aluminum RIE
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Nanoimprint
Lithography
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Development - Nano Wire Grid Polarizer
S-polarized Light
Projection TV
Unpolarized Light
Pitch
P-polarized Light
50 nm HalfPitch Stamp
Imprinted
Polymer Pattern
Contrast Ratio > 2,000,
Transmission > 83 % at λ= 470 nm
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Application
Technology
Photonic Band Gap Device
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‰ Nanoimprinting of Photonic Crystal Waveguides
Future vision of hybrid optical integration of an
optical transceiver with silicon photonic
components and conventional CMOS drivers
<SEM Image of Master>
Dimension
r = 150 nm
a = 400 nm
<SEM and AFM Images of Nanoimprinted Photonic Crystal Waveguide>
Dimension
r = 160 nm
a = 405 nm
Height = 335~340 nm
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‰ Completed Photonic Crystal Waveguide
Dimension : 7.7 X 13.5 ㎛
<Near Field Pattern of
Photonic Crystal Waveguide>
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Tool
Technology
Single-step UV-NIL tool
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UV-based Nanopatterning Equipment - CNMM
„ Area : 4 inch Wafer
„ Min. Feature Size ≤ 100 nm
„ Chip-size Multi-Head Imprinting
Nano-Precision
Nano-PrecisionStage:
Stage:3nm
3nm
Controller
Flexure stage
X-Y stage
for parallelization
UV System
3-Axis
3-AxisNano
NanoLeveling
Leveling
Overlay
Overlay&&Alignment
Alignment
UV
UVLight
LightSource
Source
Vibration
VibrationControl
Control
NanoImprint
Equipment
Imprinting Head
XYZ Stage
Vibration Isolator
100nm
86nm
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Summary
NIL has several advantages over optical lithography
High resolution (feature size ∼ 10 nm)
low cost
Challenging issues
Minimizing defects
Residual layer thickness control
1×stamp inspection and cleaning
10 nm scale overlay alignment
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Thank You!
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