MEMS Two-Phase Vapor Escape MEMS Two-Phase Vapor Escape Heat Exchanger Heat Exchanger

Milnes David

Tarun Khurana

Christopher Anderson

Concepts

1. Evaporator with hydrophobic, porous membrane

Heat flux

Liquid inlet

Vapor outlet

Silicon

Liquid channel Vapor channelHydrophobic, porous

membrane

Hydrophobic PTFE, AdvantecMFS

Polycarbonate, GE Wet etched pores combined with porous membrane. Etched pores act

as bubble traps [Meng, 06]

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

Process Layout

15. Backside pattern (through etch)

16. Through etch (STS DRIE)

17. Final released device

18. Adhesive coat on transfer substrate

19. Contact printing of adhesive

20. Membrane attachment via UV curing

21. Attachment of patterned double sticky tape (vapor channel)

22. Top cover integration

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.

Membrane Test Structure

Fluid in

Acrylic Structure

Membrane

Membrane Test Setup

Pressurized Liquid Chamber

Pressure Sensor

Membrane Test Structure

Pressurized Liquid Chamber

Pressure Sensor

Membrane Test Structure

Temperature Sensor Electronics

Power Supply