Process Sequence: Pressure-Actuated Valve

Process Sequence:Pressure-Actuated Valve

ENMA490

October 14, 2003

Outline

•Wafer 1 Fabrication

–Silicon Substrate

–SU-8 Bottom Fluid Layer

–PDMS Gas Layer

–PDMS Thin Flex Layer

–Wafer 1 Layer Integration

•Wafer 2 Fabrication

–Pyrex Substrate

–SU-8 Cover Layer

–SU-8 Top Fluid Layer

•Integration of Wafer 1and Wafer 2

•PDMS Layer Removaland Attachment

Pyrex Substrate

SU-8 Cover Layer

PDMS Thin Flex Layer

PDMS Gas Layer

SU-8 Bottom Fluid Layer

Substrate (Si)

FINAL RESULT

Wafer 1

Wafer 2

SU-8 Top Fluid Layer

Wafer 1: Process SequenceSilicon SubstrateSU-8 Bottom Fluid Layer

• Start with a 4” diameter Silicon Wafer.

• Spin on SU-8 photoresist (orange).

• Pre-bake at 95°C.

Silicon

• Align wafer with Mask 1 –Bottom Fluid Layer Mask.

• Expose SU-8 to UV light.

• Post-bake at 95°C.

STEP 1

STEP 3

STEP 2

SU-8 Photoresist

• Develop SU-8 in SU-8 developer.

STEP 4

Wafer 1: Process SequencePDMS Gas Layer

STEP 1

STEP 2

STEP 3

SU-8 Photoresist

• Spin on SU-8 photoresist (orange).

• Pre-bake at 95°C.

• Align wafer with Mask 2 –Gas Layer Mask.

• Expose SU-8 to UV light.

• Post-bake at 95°C.

STEP 4

• Develop SU-8 in SU-8 developer.

• Dip wafer in 0.1 M sodium dodecyl sulfate(SDS) adhesion barrier and let dry naturally.

STEP 5

• 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

Silicon

• Start with a 4” diameter Silicon Wafer.

Wafer 1: Process SequencePDMS Thin Flex Layer

STEP 1

STEP 2

STEP 3

SU-8 Photoresist

• Spin on SU-8 photoresist (orange).

• Pre-bake at 95°C.

• Align wafer with Mask 3 –Thin Flex Layer Mask.

• Expose SU-8 to UV light.

• Post-bake at 95°C.

STEP 4

• Develop SU-8 in SU-8 developer.

• Dip wafer in 0.1 M sodium dodecyl sulfate(SDS) adhesion barrier and let dry naturally.

STEP 5

• 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

Silicon

• Start with a 4” diameter Silicon Wafer.

Wafer 1: Layer Integration

Silicon

SU-8 Photoresist

PDMS

• Take the Silicon substrate and SU-8 BottomFluid Layer.

STEP 1

STEP 2

• Align the PDMS Gas Layer on top of the

SU-8 Bottom Fluid Layer.

• See Theresa’s Assembly Slide for PDMS layer

removal and attachment

STEP 3

• Align the PDMS Thin Flex Layer on top

of the PDMS Gas Layer.

• See Theresa’s Assembly Slide for PDMS layer

removal and attachment

PDMS Thin Flex Layer

PDMS Gas Layer

SU-8 Bottom FluidLayer

Substrate (Si)

WAFER 1: COMPLETE

Wafer 2: Process SequencePyrex SubstrateSU-8 Cover Layer

• Start with a 4” Pyrex Wafer and drill therequired throughput holes in the wafer (use abarrier such as tape (on the bottom) to avoidproblems in subsequent steps).

STEP 2

• Spin on SU-8 photoresist (orange).

• Pre-bake at 95°C.

STEP 1

STEP 3

• Align wafer with Mask 4–SU-8 Cover Layer Mask.

• Expose SU-8 to UV light.

• Post-bake at 95°C.

Silicon

SU-8 Photoresist

Not exposed to UV-light (will be developed away).

Wafer 2: Process SequenceAdding SU-8 Top Fluid Layer

Silicon

SU-8 Photoresist

STEP 1

• Start with the wafer from the Pyrex

Substrate and SU-8 Cover Layer

Not exposed to UV-light (will be developed away).

STEP 2

• Spin on another layer of SU-8 photoresist(orange).

• Pre-bake at 95°C.

STEP 3

Not exposed to UV-light (will be developed away).

• Align wafer with Mask 5–SU-8 Top Fluid

Layer Mask.

• Expose SU-8 to UV light.

• Post-bake at 95°C.

STEP 4

• Develop SU-8 in SU-8 developer.

Pyrex Substrate

WAFER 2: COMPLETE

Integration of Wafer 1 and Wafer 2

PDMS Thin Flex Layer

PDMS Gas Layer

SU-8 Bottom FluidLayer

WAFER 1

Pyrex Substrate

SU-8 Top Fluid Layer

SU-8 Cover Layer

WAFER 2 Inverted

Pyrex Substrate

SU-8 Top Fluid Layer

SU-8 Cover Layer

PDMS Thin Flex Layer

PDMS Gas Layer

SU-8 Bottom Fluid Layer

Substrate (Si)

FINAL RESULT

Wafer 1

Wafer 2

Substrate (Si)

PDMS Layer Removal and Attachment*Theresa Valentine

•Gently loosen edges of cured PDMS withrazor blade

•Submerge PDMS wafer in dish of methanol

•Hold one edge of PDMS with tweezers andgently pull from wafer (keeping in methanolas much as possible)

•Remove wafer from dish and allow PDMSto float

•Slide (electrode) wafer to be assembledunder PDMS layer in dish

•Coarse align PDMS to wafer while in dish

•Remove wafer and PDMS from dish andalign carefully by hand or undermicroscope, dropping methanol on ifsticking occurs, then let dry.

•Materials:

–Methanol

•Equipment:

–Razorblade

–Tweezers

Alternate Sequence

•In addition to the Process sequence described above,another mask set is being created to create the samedesign with all PDMS layers.

•The procedure is very similar, except the current SU-8layers will not be patterned on the device itself, but willrather be used as a mold to create PDMS layers, whichwill then be removed and layered to create the device.

•Wafer 1 Fabrication

–Silicon Substrate

–PDMS Bottom Fluid Layer

–PDMS Gas Layer

–PDMS Thin Flex Layer

•Wafer 2 Fabrication

–Pyrex Substrate

–PDMS Cover Layer

–PDMS Top Fluid Layer