Transcript BioMEMS Device Fabrication Procedure

BioMEMS Device
Fabrication Procedure
Theresa Valentine
ENMA490
September 25, 2003
Steps
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Electrode Fabrication
Mold or Fluid Control Fabrication (SU-8)
Molded Fluid Control Fabrication (PDMS)
Assembly
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BioMEMS Device Fabrication Procedure
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Electrode Fabrication
• Materials:
• Equipment:
– Pyrex wafer, 100 mm diameter,
0.5 mm thickness
– Cr and Au evaporation targets
– Acetone, methanol, isopropyl
alcohol (IPA)
– HMDS
– Shipley 1813 photoresist
– Shipley 352 developer
– Au etchant
– Cr etchant
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E-beam evaporation system
Spin-coating system
Contact aligner
Hotplate
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Metal Deposition
Si
• Begin with bare double-polished 4” Pyrex
wafer (white).
Cr
• Deposit 90Å Cr adhesion layer (green) with
e-beam evaporation.
Au
• Deposit 2000Å Au (yellow) with e-beam
evaporation.
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Electrode Patterning
1813
• Apply HMDS primer, wait 1 min, and spin (3000 rpm
for 30 sec).
• Spin on photoresist 1813 (blue) (3000 rpm for 30 sec).
• Soft bake for 1 min at 100C.
• Align wafer with Mask 1 – electrode mask.
• Expose photoresist to UV light for total dose of 180200 mJ/cm2.
• Develop photoresist for 30 s in Shipley 352
developer. (Resist is positive, so exposed areas are
removed.)
• Hard-bake photoresist for 10 min at 120C.
• Etch with gold etchant (TFA, Transene Co.), 100 s.
• Etch with chromium mask etchant (Transene), 25 s.
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Completed Electrode Wafer
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Mold or Fluid Control Fabrication
(SU-8)
• Materials:
• Equipment:
– SU-8 50 negative resist
– SU-8 developer
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– Spin-coating system
– Hotplate
– Contact aligner
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SU-8 Coating/Patterning
SU-8
• Spin on SU-8 photoresist (orange).
• Pre-bake at 95°C.
• Align wafer with Mask 2 – channel/reservoir
mask.
• Expose SU-8 to UV light.
• Post-bake at 95°C.
• Develop SU-8 in SU-8 developer. (Resist is
negative, so unexposed areas are removed.)
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Completed Mold Wafer
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Molded Fluid Control Fabrication
(PDMS)
• Materials:
• Equipment:
– Sodium dodecyl sulfate
(SDS)
– PDMS (Sylgard 184)
– PDMS curing agent
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– Spin-coating system
– Box furnace
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PDMS Fabrication
• Dip wafer in 0.1 M sodium dodecyl sulfate
(SDS) adhesion barrier and let dry naturally.
• Mix PDMS (Sylgard 184, Dow-Corning) 10:1
with curing agent.
• Spin on PDMS (purple).
• Bake in box furnace for 2 h at 70°C.
PDMS
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Assembly
• Materials:
– Methanol
• Equipment:
– Razor blade
– Tweezers
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• Gently loosen edges of cured PDMS with
razor blade
• Submerge PDMS wafer in dish of methanol
• Hold one edge of PDMS with tweezers and
gently pull from wafer (keeping in methanol
as much as possible)
• Remove wafer from dish and allow PDMS to
float
• Slide (electrode) wafer to be assembled under
PDMS layer in dish
• Coarse align PDMS to wafer while in dish
• Remove wafer and PDMS from dish and
align carefully by hand or under microscope,
dropping methanol on if sticking occurs,
then let dry.
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Complete Assembled Wafer
(2560x2560 um)
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