1. Temperature Sensors on Flexible Substrates
Z. Celik-Butler, D. Butler
and M. Chitteboyina
Nanotechnology Research and Teaching Facility University of Texas at Arlington
March 13, 2009

2. Temperature Sensor Temperature Sensor - CoventorWare Model
Flexible superstrate
0.15cm x 0.05cm x cm
Top surface is in contact with the structure
cross-section cut
Flexible substrate
Temperature sensor is connected to external flexible circuitry through the flexible substrate

3. Temperature Sensor Z-scale exaggerated 5 times Aluminum
Insulation Layers
Sensor Element
Right arm of the temperature sensor
Left arm of the temperature sensor
Flexible Substrate

4. Fabrication Process Flow for the Temperature Sensor
Clean silicon wafer

5. Fabrication Process Flow for the Temperature Sensor
100 nm silicon nitride layer

6. Fabrication Process Flow for the Temperature Sensor
Flexible Substrate
Polyimide ~ 40 µm

7. Fabrication Process Flow for the Temperature Sensor
Right electrode of the sensor

8. Fabrication Process Flow for the Temperature Sensor
Sensor Element

9. Fabrication Process Flow for the Temperature Sensor
First Insulation Layer

10. Fabrication Process Flow for the Temperature Sensor
Left electrode of the sensor

11. Fabrication Process Flow for the Temperature Sensor
Second Insulation Layer

12. Fabrication Process Flow for the Temperature Sensor
Flexible Superstrate
Polyimide ~ 40 µm
Undercut made to access the sensor
Second Insulation Layer
Silicon Nitride ~ 100 nm

13. Fabrication Process Flow for the Temperature Sensor
Top aluminum surface will be in contact with the structure
Aluminum ~ 400 nm

14. Fabrication Process Flow for the Temperature Sensor
Back side view of the Temperature Sensor
Sensor are connected to flexible circuitry through the flexible substrate

15. Temperature Sensor Simulation Results
Temperature pulse applied on the top aluminum surface
370.5 K
300.0 K
Temperature Sensor CoventorWare Model
Bottom Flexible substrate kept either floating or fixed at 300 K
Simulated, heating thermal time constant = 0.07 ms
cooling thermal time constant = 0.67 ms

16. Temperature Sensor Fabrication
STEP 1
STEP 2
STEP 3
Right arm of the sensor
Sensor Element
First Insulation Layer
STEP 4
STEP 5
STEP 6, 7, 8
Left arm of the sensor
Second Insulation Layer
Spin-coat and pattern polyimide superstrate layer
Deposit Aluminum layer
Etch the back-side of the wafer and get access to bond-pads

17. Temperature Sensor Fabrication
Spin-coat and pattern polyimide superstrate layer
Then deposited Aluminum on top of the superstrate layer to make contact with the structure

18. Temperature Sensor Results
TS 80x80 µm Device 1
TS 80x80 µm Device 2