Membrane Test Structure

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MEMS Two-Phase Vapor Escape Heat Exchanger
Milnes David Tarun Khurana Christopher Anderson
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Concepts

1. Evaporator with hydrophobic, porous membrane

Liquid channel
Vapor channel
Hydrophobic, porous membrane
Vapor outlet
Liquid inlet
Silicon
Heat flux
Hydrophobic PTFE, AdvantecMFS
Wet etched pores combined with porous membrane.
Etched pores act as bubble traps Meng, 06
Polycarbonate, GE
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Process Flow

1. Diffusion Clean
2. Oxide Growth
3. Al. Sputter
4. Backside Pattern (heaters sensors)
5. Al Etch
6. Ashing
7. PRX 1000 Clean
8. Backside LTO deposition
9. Backside protect
10. Front-side Oxide Etch (HF)
11. Front-side pattern (channels)
12. Front-side channel etch (STSDRIE)
13. Backside pattern (bond pads)
14. Pad etch

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Process Layout

• Backside pattern (through etch)
• Through etch (STS DRIE)
• Final released device
• Adhesive coat on transfer substrate
• Contact printing of adhesive
• Membrane attachment via UV curing
• Attachment of patterned double sticky tape (vapor
  channel)
• Top cover integration

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Materials Acquired

• Membranes
• Polycarbonate 0.1 um. 0.2 um, 0.4 um and 3 um
• Teflon 0.2 um
• Membrane characterization apparatus has been
  built.
• Teflon coating of Polycarbonate membranes using
  similar setup.
• Adhesives
• 5 different types on order.
• Challenge
• Temperature Stability (chosen adhesives stable to
  180 oC).
• Adhesion to membrane and silicon.
• 3 of chosen adhesives work well with
  Polycarbonate and Si
• 2 of chosen adhesives work well with
  Polycarbonate and SiO2.
• No appropriate adhesive for Tefon and Si.
• Characterization apparatus to be designed.

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Membrane Test Structure
Acrylic Structure
Membrane
Fluid in
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Membrane Test Setup
Pressurized Liquid Chamber
Membrane Test Structure
Pressure Sensor
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Temperature Sensor Electronics
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Power Supply