1

Temperature Sensors on Flexible Temperature Sensors on Flexible SubstratesSubstrates

Z. Celik-Butler, D. Butler

and M. ChitteboyinaNanotechnology Research and Teaching Facility

University of Texas at Arlingtonhttp://www.uta.edu/engineering/nano/

March 13, 2009

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Temperature Sensor - CoventorWare Model

Top surface is in contact with the

structure

Temperature sensor is connected to external flexible circuitry through the

flexible substrate

Temperature Sensor

Flexible superstrate

Flexible substrate

0.15cm x 0.05cm x 0.005 cm

cross-section cut

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Temperature Sensor

Z-scale exaggerated 5 times

Aluminum

Flexible Substrate

Right arm of the temperature sensorLeft arm of the

temperature sensor

Sensor Element

Insulation Layers

4

Fabrication Process Flow for the Temperature Sensor

Clean silicon wafer

5

Fabrication Process Flow for the Temperature Sensor

100 nm silicon nitride layer

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Fabrication Process Flow for the Temperature Sensor

Flexible Substrate

Polyimide ~ 40 µm

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Fabrication Process Flow for the Temperature Sensor

Right electrode of the sensor

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Fabrication Process Flow for the Temperature Sensor

Sensor Element

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Fabrication Process Flow for the Temperature Sensor

First Insulation Layer

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Fabrication Process Flow for the Temperature Sensor

Left electrode of the sensor

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Fabrication Process Flow for the Temperature Sensor

Second Insulation Layer

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Fabrication Process Flow for the Temperature Sensor

Second Insulation Layer

Silicon Nitride ~ 100 nm

Flexible Superstrate

Polyimide ~ 40 µm

Undercut made to access the sensor

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Fabrication Process Flow for the Temperature Sensor

Top aluminum surface will be in contact with the structure

Aluminum ~ 400 nm

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Fabrication Process Flow for the Temperature Sensor

Sensor are connected to flexible circuitry through the

flexible substrate

Back side view of the Temperature Sensor

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Temperature Sensor Simulation Results

Bottom Flexible substrate kept either

floating or fixed at 300 K

Temperature Sensor CoventorWare Model

Simulated, heating thermal time constant = 0.07 ms

cooling thermal time constant = 0.67 ms

300

310

320

330

340

350

360

370

380

0 0.5 1 1.5 2 2.5 3

Thermal Transient Analysis of the Temperature Sensor

Te

mp

era

ture

(K

)

Time (ms)

Temperature pulse applied on the top aluminum surface

370.5 K

300.0 K

16April 28 2009

Temperature Sensor Fabrication

Right arm of the sensor Sensor Element First Insulation Layer

Left arm of the sensor Second Insulation Layer

STEP 1 STEP 2 STEP 3

STEP 4 STEP 5 Spin-coat and pattern polyimide superstrate layer

Deposit Aluminum layer

Etch the back-side of the wafer and get access to bond-pads

STEP 6, 7, 8

17July 21 2009

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

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Temperature Sensor Results

Resistance vs Temperature

3.2

3.25

3.3

3.35

3.4

3.45

3.5

3.55

3.6

25 35 45 55 65 75 85

Temperature (C)

Res

ista

nce

(MO

hms)

TS 80x80 µm Device 1 TS 80x80 µm Device 2

Resistance vs Temperature

3.3

3.4

3.5

3.6

3.7

3.8

20 30 40 50 60 70 80 90

Temperature (C)R

esis

tanc

e (M

Ohm

s)