1. BioMEMS Device Fabrication Procedure
Theresa Valentine
ENMA490
September 25, 2003

2. BioMEMS Device Fabrication Procedure
Steps
Electrode Fabrication
Mold or Fluid Control Fabrication (SU-8)
Molded Fluid Control Fabrication (PDMS)
Assembly
November 22, 2018
BioMEMS Device Fabrication Procedure

3. Electrode Fabrication
Materials:
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
Equipment:
E-beam evaporation system
Spin-coating system
Contact aligner
Hotplate
November 22, 2018
BioMEMS Device Fabrication Procedure

4. BioMEMS Device Fabrication Procedure
Metal Deposition
Begin with bare double-polished 4” Pyrex wafer (white). Si
Deposit 90Å Cr adhesion layer (green) with e-beam evaporation. Cr
Deposit 2000Å Au (yellow) with e-beam evaporation. Au
November 22, 2018
BioMEMS Device Fabrication Procedure

5. BioMEMS Device Fabrication Procedure
Electrode Patterning
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.
1813
Align wafer with Mask 1 – electrode mask.
Expose photoresist to UV light for total dose of 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.
November 22, 2018
BioMEMS Device Fabrication Procedure

6. Completed Electrode Wafer
November 22, 2018
BioMEMS Device Fabrication Procedure

7. Mold or Fluid Control Fabrication (SU-8)
Materials:
SU-8 50 negative resist
SU-8 developer
Equipment:
Spin-coating system
Hotplate
Contact aligner
November 22, 2018
BioMEMS Device Fabrication Procedure

8. SU-8 Coating/Patterning
Spin on SU-8 photoresist (orange).
Pre-bake at 95°C.
SU-8
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.)
November 22, 2018
BioMEMS Device Fabrication Procedure

9. BioMEMS Device Fabrication Procedure
Completed Mold Wafer
November 22, 2018
BioMEMS Device Fabrication Procedure

10. Molded Fluid Control Fabrication (PDMS)
Materials:
Sodium dodecyl sulfate (SDS)
PDMS (Sylgard 184)
PDMS curing agent
Equipment:
Spin-coating system
Box furnace
November 22, 2018
BioMEMS Device Fabrication Procedure

11. BioMEMS Device Fabrication Procedure
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
November 22, 2018
BioMEMS Device Fabrication Procedure

12. BioMEMS Device Fabrication Procedure
Assembly
Materials:
Methanol
Equipment:
Razor blade
Tweezers
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.
November 22, 2018
BioMEMS Device Fabrication Procedure

13. Complete Assembled Wafer (2560x2560 um)
November 22, 2018
BioMEMS Device Fabrication Procedure