Presentation - NanoSpain Conf

Novel 3D embedded microfluidic
channels for BioMEMS
applications
M.Aguirregabiria, F.J. Blanco, J. Berganzo, M. T. Arroyo,
M. Tijero, J. M. Ruano, J. García, I. Aramburu, Kepa Mayora.
MEMS/MST Department
Ikerlan
1st Nanospain Workshop. 10-12 March 2004. San Sebastian, Spain
1
Outline
1.
Introduction
2.
Goals
3.
Fabrication process
-Photolithography
-Bonding
4.
Results
5.
Conclusions
6.
Future work
1st Nanospain Workshop. 10-12 March 2004. San Sebastian, Spain
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Introduction
1.
Introduction
2.
Goals
3.
Fabrication process
-Photolithography
-Bonding
4.
Two-dimensional electrophoresis
chip to separate proteins
Separation according
to molecular weight
Separation according
to isoelectric point
Results
-Photolithography
-Bonding
5.
Conclusions
6.
Future work
Microfluidic circuitry
fabricated on SU8 with
this fabrication process
1st Nanospain Workshop. 10-12 March 2004. San Sebastian, Spain
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Sealed microchannel
1.
Introduction
2.
Goals
3.
Fabrication process
-Photolithography
-Bonding
4.
Sealed microchannel: two photopatterned SU8 layers,
bonded together
Results
-Photolithography
-Bonding
5.
Conclusions
6.
Future work
1st Nanospain Workshop. 10-12 March 2004. San Sebastian, Spain
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SU8
1.
Introduction
2.
Goals
3.
•
Negative tone epoxy photoresist
•
Good properties:
Crosslinked on exposure to UV light
2.
Mechanically reliable
3.
Chemically resistant
4.
Excellent optical properties
Fabrication process
-Photolithography
-Bonding
4.
1.
Results
-Photolithography
-Bonding
5.
Conclusions
6.
Future work
•
Problem: difficult to seal the microchannels
Solution: Our bonding process
1st Nanospain Workshop. 10-12 March 2004. San Sebastian, Spain
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Polymer adhesive bonding
What is polymer adhesive wafer bonding?
1.
Introduction
2.
Goals
3.
Fabrication process
-Photolithography
“Gluing two (wafer) surfaces together”
• Wafers (coated by a polymer)
inside the bond chamber under
vacuum conditions.
-Bonding
4.
Results
-Photolithography
• Wafers contact.
-Bonding
5.
Conclusions
6.
Future work
• Applied Force and Temperature.
1st Nanospain Workshop. 10-12 March 2004. San Sebastian, Spain
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Goals of the bonding process
1.
Introduction
2.
Goals
3.
Fabrication process
-Photolithography
•Fabrication of 3D embedded microfluidic channels for
electrophoresis application
•Development of a new low temperature CMOS
compatible bonding process between two photopatterned
SU8 layers
-Bonding
4.
Results
-Photolithography
-Bonding
5.
Conclusions
•Optimisation of the photolithography process to obtain:
•Uniform SU8 films
•Low stress
•Good adhesive properties
6.
Future work
1st Nanospain Workshop. 10-12 March 2004. San Sebastian, Spain
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Photolithography process
Dehydration of the substrate
1.
Introduction
2.
Goals
Soft bake to remove the solvent
3.
Fabrication process
UV Exposure to begin the polimerization
Spin coating
-Photolithography
Post bake to polimerise the SU8
-Bonding
Development
4.
Results
-Photolithography
-Bonding
5.
Conclusions
6.
Future work
Critical parameters to obtain high uniformity, low stress
and good adhesive properties:
1.
The spinning step
high uniformity
2.
Temperature ramps during bake steps
3.
Crosslinking level of SU8 layers
properties
low stress
good adhesive
1st Nanospain Workshop. 10-12 March 2004. San Sebastian, Spain
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Bonding Process
1.
Introduction
2.
Goals
3.
Fabrication process
1.Top wafer. Silicon/Silicon
oxidised or Pyrex.
1.Bottom wafer.
Silicon/Silicon processed or
Pyrex.
2. SU-8 spin coating (20-50
µm)
2. SU-8 spin coating (20-50
µm)
-Photolithography
-Bonding
3. SU-8 UV photolithography
3. SU-8 UV photolithography
4.
Results
4. Bonding Process
-Photolithography
-Bonding
5.
Conclusions
5. Final encapsulated device
6.
Future work
5.Release oxidised wafer
(HF Sacrificial etch)
1st Nanospain Workshop. 10-12 March 2004. San Sebastian, Spain
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Results of photolithography (I):
Uniformity
•We have obtained high uniformity SU8 films: StD 0,3-1%
vs 3-4% of manufacturer recommended recipe
1.
Introduction
Pareto Chart of the Standardized Effects
2.
Goals
3.
Fabrication process
(response is StD espe, Alpha = ,50)
D
-Photolithography
-Bonding
Results
-Photolithography
-Bonding
DF
Conclusions
Future work
Accel. (1st
ramp)
Time (1st
C: ramp)
AD
D:
F
Speed (2nd
Ramp)
AB
Accel. (2nd
E: ramp)
BD
F:
C
6.
B:
E
B
5.
Speed (1st
Ramp)
DE
A
4.
A:
Time (2nd
ramp)
AC
0
1
2
3
4
5
6
1st Nanospain Workshop. 10-12 March 2004. San Sebastian, Spain
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Results of photolithography (I):
Uniformity
1.
Introduction
2.
Goals
3.
Fabrication process
Polymer thickness uniformity (100ºC, 300Kpa, 20 minutes)
-Photolithography
-Bonding
4.
Results
-Photolithography
-Bonding
Bonded Area (%)
100
80
60
40
20
0
0
5.
Conclusions
6.
Future work
0,5
1
SU-8 Thickness StD
1,5
1st Nanospain Workshop. 10-12 March 2004. San Sebastian, Spain
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Results of photolithography (II): stress
•Microcracking is reduced.
1.
Introduction
2.
Goals
•Low stress-? New temperature ramps during the
baking steps.
Standard recipe (4000 rpm). Cracking
3.
Fabrication process
-Bonding
4.
Results
-Photolithography
-Bonding
5.
Conclusions
Temperature (ºC)
-Photolithography
90ºC (7 minutes)
100
90
80
70
60
50
40
30
20
10
0
New ramps (4000 rpm). No Cracking
0
20
40
60
80
100
Time (minutes)
6.
Future work
1st Nanospain Workshop. 10-12 March 2004. San Sebastian, Spain
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Results of photolithography (III):
Adhesive properties
1.
Introduction
We have optimised the polymerisation level before
bonding to obtain:
2.
Goals
•Good adhesive properties
3.
Fabrication process
•Good sidewall profiles and no blocked channels
-Photolithography
-Bonding
4.
Results
-Photolithography
-Bonding
5.
Conclusions
6.
Future work
•polymerization level too high ? the SU8 layers do not
bond together
• polymerization level too low ? blocked channels have
obtained
1st Nanospain Workshop. 10-12 March 2004. San Sebastian, Spain
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Results of photolithography (III):
Adhesive properties
Optimised polymerisation level
before bonding.
1.
Introduction
2.
Goals
No blocked Microchannels
UV exposure:160 mJ/cm2
3.
Fabrication process
PEB T = 90 ºC
-Photolithography
Bond T = 100ºC
-Bonding
4.
Results
Blocked microchannels
-Photolithography
Blocked Microchannels
UV exposure:150 mJ/cm2
-Bonding
PEB T = 85ºC
5.
Conclusions
6.
Future work
Bond T = 100ºC
Polymerisation level too low
Partially blocked microchannels
1st Nanospain Workshop. 10-12 March 2004. San Sebastian, Spain
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Bonding results
Bonding Pressure (StD-0,3 %) (100ºC, 100-300Kpa, 20 minutes)
Introduction
2.
Goals
3.
Fabrication process
-Photolithography
-Bonding
100
Bond Area (%)
1.
80
60
40
20
0
4.
Results
0
100
200
300
Bond Pressure (KPa)
-Photolithography
400
-Bonding
Bonding Temperature (StD-0,3 %) (300 KPa, 90-120ºC, 20 minutes)
5.
Conclusions
•90ºC
no bonding
6.
Future work
•100ºC
optimum value
•120ºC
blocked channels
1st Nanospain Workshop. 10-12 March 2004. San Sebastian, Spain
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Bonding test (I): Open
crack method
1.
Introduction
2.
Goals
3.
Fabrication process
-Photolithography
-Bonding
4.
Results
-Photolithography
-Bonding
5.
Conclusions
6.
Future work
The adhesion between the two SU8 layers is greater than the
adhesion between the pyrex and SU8.
The wafer
was broken
after the blade
insertation
1st Nanospain Workshop. 10-12 March 2004. San Sebastian, Spain
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Bonding test (II):
tensile strenght test
1.
Introduction
2.
Goals
3.
Fabrication process
-Photolithography
-Bonding
4.
The bonding strenght has been evaluated by the tensile
strenght tests. Bond strenghts about 8 MPa have been
obtained.
Diced bonded
device
Pulling head
Results
-Photolithography
-Bonding
5.
Conclusions
6.
Future work
1st Nanospain Workshop. 10-12 March 2004. San Sebastian, Spain
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3D embedded microchannels
1.
Introduction
2.
Goals
45 µm
52 µm
12 µm
3.
100 µm
Fabrication process
-Photolithography
-Bonding
4.
Bonding interface between Si wafers.
Bonding interface between Si and pyrex
wafers.
Results
-Photolithography
-Bonding
5.
Conclusions
6.
Future work
Embedded
interconected
microchannels
between silicon
wafers
52
µm
90 µm
1st Nanospain Workshop. 10-12 March 2004. San Sebastian, Spain
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3D embedded microchannels
1.
Introduction
2.
Goals
3.
Fabrication process
-Photolithography
-Bonding
4.
Results
-Photolithography
-Bonding
5.
Conclusions
6.
Future work
The releasing step simplify the packaging and
introduction of the sample into reservoirs.
1st Nanospain Workshop. 10-12 March 2004. San Sebastian, Spain
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Microfluidic test
1.
Introduction
2.
Goals
3.
Fabrication process
Mixing zone
The utility of the circuitry
is demonstrated
introducing DI water into
the microchannels.
-Photolithography
-Bonding
4.
Results
-Photolithography
-Bonding
5.
Conclusions
6.
Future work
The channels are filled at
different levels and the
liquids are mixed in the
interconnected site.
1st Nanospain Workshop. 10-12 March 2004. San Sebastian, Spain
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Conclusions
1.
Introduction
2.
Goals
3.
Fabrication process
•
High Uniformity adhesive SU-8 thick films are obtained.
•
Low temperature wafer level bonding (Si , Si (preprocessed) and Si-Pyrex) have been developed, using
-Photolithography
-Bonding
4.
SU-8 as intermediate layer.
Results
-Photolithography
•
High strengh bonds have been obtained
•
Novel 3D smooth and vertical microfluidic channels have
-Bonding
5.
Conclusions
been successfully fabricated.
6.
Future work
1st Nanospain Workshop. 10-12 March 2004. San Sebastian, Spain
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Future work
1.
Introduction
•Bonding with thick layers (100 - 500µm)
2.
Goals
3.
Fabrication process
-Photolithography
-Bonding
4.
Results
-Photolithography
-Bonding
5.
•Evaluation of other sacrificial layers to release the
top wafer
•Packaging of devices
Conclusions
•Fabrication of two dimensional electrophoresis chip
6.
Future work
1st Nanospain Workshop. 10-12 March 2004. San Sebastian, Spain
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Acknowledgments
I would like to thank to:
• MST department of Ikerlan:
Javier
and
Iñigo Aramburu , Maria Arroyo, Javier Berganzo, Francisco
Blanco, Jorge Garcia, Irune Rojo, Jesus Ruano, Maria Tijero
Kepa Mayora
•Basque Government, under ETORTEK program and trought the
Technology Center Foundation, for financing support
1st Nanospain Workshop. 10-12 March 2004. San Sebastian, Spain
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