BioMEMS Device Fabrication ProcedureStepsElectrode FabricationMetal DepositionElectrode PatterningCompleted Electrode WaferMold or Fluid Control Fabrication (SU-8)SU-8 Coating/PatterningCompleted Mold WaferMolded Fluid Control Fabrication (PDMS)PDMS FabricationAssemblyComplete Assembled Wafer (2560x2560 um)BioMEMS DeviceFabrication ProcedureTheresa ValentineENMA490September 25, 2003January 13, 2019 BioMEMS Device Fabrication Procedure 2Steps•Electrode Fabrication•Mold or Fluid Control Fabrication (SU-8)•Molded Fluid Control Fabrication (PDMS)•AssemblyJanuary 13, 2019 BioMEMS Device Fabrication Procedure 3Electrode 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–HotplateJanuary 13, 2019 BioMEMS Device Fabrication Procedure 4Metal 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.AuJanuary 13, 2019 BioMEMS Device Fabrication Procedure 5Electrode 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.• Align wafer with Mask 1 – electrode mask.• Expose photoresist to UV light for total dose of 180-200 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.1813January 13, 2019 BioMEMS Device Fabrication Procedure 6Completed Electrode WaferJanuary 13, 2019 BioMEMS Device Fabrication Procedure 7Mold or Fluid Control Fabrication(SU-8)•Materials:–SU-8 50 negative resist–SU-8 developer•Equipment:–Spin-coating system–Hotplate–Contact alignerJanuary 13, 2019 BioMEMS Device Fabrication Procedure 8SU-8 Coating/Patterning• Align wafer with Mask 2 – channel/reservoir mask.• Expose SU-8 to UV light.• Post-bake at 95°C.• Spin on SU-8 photoresist (orange).• Pre-bake at 95°C.SU-8• Develop SU-8 in SU-8 developer. (Resist is negative, so unexposed areas are removed.)January 13, 2019 BioMEMS Device Fabrication Procedure 9Completed Mold WaferJanuary 13, 2019 BioMEMS Device Fabrication Procedure 10Molded Fluid Control Fabrication (PDMS)•Materials:–Sodium dodecyl sulfate (SDS)–PDMS (Sylgard 184)–PDMS curing agent•Equipment:–Spin-coating system–Box furnaceJanuary 13, 2019 BioMEMS Device Fabrication Procedure 11PDMS 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. PDMSJanuary 13, 2019 BioMEMS Device Fabrication Procedure 12Assembly•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.January 13, 2019 BioMEMS Device Fabrication Procedure 13Complete Assembled Wafer(2560x2560
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