the resistive properties of thin carbon films from pyrolized su-8

The Resistive Properties of Thin Carbon Films from Pyrolized SU-8

Justin Little

Department of Mechanical and Aerospace EngineeringUniversity of California, Irvine

Funded by the National Science Foundation

Mentors: Professor Richard Nelson

Professor John Larue

Support: Allen Kine and Hideo Morita

The Resistive Properties of Thin Carbon Films from Pyrolized SU-8

Justin Little

Department of Mechanical and Aerospace EngineeringUniversity of California, Irvine

Funded by the National Science Foundation

Mentors: Professor Richard Nelson

Professor John Larue

Support: Allen Kine and Hideo Morita

Project Description….

1. Design a die that will use a four point Kelvin bridge resistance measurement for pyrolized SU-8

2. Design and manufacture high temperature die housing that will incorporate the resistance measurement

3. Fabricate die in the INRF

4. Use the Die Housing to perform the resistance measurements

The Resistive Properties of Thin Carbon Films from Pyrolized SU-8

Justin Little

Department of Mechanical and Aerospace EngineeringUniversity of California, Irvine

Funded by the National Science Foundation

Mentors: Professor Richard Nelson

Professor John Larue

Support: Allen Kine and Hideo Morita

What is SU-8?• Photosensitive Epoxy

• Originally developed for the electronics industry

•Used as a Negative Photoresist

• Has many attributes that make it suitable for MEMS

The Resistive Properties of Thin Carbon Films from Pyrolized SU-8

Justin Little

Department of Mechanical and Aerospace EngineeringUniversity of California, Irvine

Funded by the National Science Foundation

Mentors: Professor Richard Nelson

Professor John Larue

Support: Allen Kine and Hideo Morita

Pyrolized SU-8…• Different properties manifest for different pyrolysis temperatures

• As pyrolysis temperature increases, ρ decreases, vertical shrinkage increases

•May achieve very high aspect ratios

•Exhibits properties similar to glassy and amorphous carbon

The Resistive Properties of Thin Carbon Films from Pyrolized SU-8

Justin Little

Department of Mechanical and Aerospace EngineeringUniversity of California, Irvine

Funded by the National Science Foundation

Mentors: Professor Richard Nelson

Professor John Larue

Support: Allen Kine and Hideo Morita

Patterning the Die…

SU-8 Pattern Before Pyrolysis

The Resistive Properties of Thin Carbon Films from Pyrolized SU-8

Justin Little

Department of Mechanical and Aerospace EngineeringUniversity of California, Irvine

Funded by the National Science Foundation

Mentors: Professor Richard Nelson

Professor John Larue

Support: Allen Kine and Hideo Morita

Patterning the Die…

Aluminum Pads Metallization Mask Final Die

The Resistive Properties of Thin Carbon Films from Pyrolized SU-8

Justin Little

Department of Mechanical and Aerospace EngineeringUniversity of California, Irvine

Funded by the National Science Foundation

Mentors: Professor Richard Nelson

Professor John Larue

Support: Allen Kine and Hideo Morita

• Quarter wafers only

• 30 minutes at 300 °C

• Increased 10 °C/min until 900 °C is achieved

• Held for one hour

• Cooled for minimum of 8 hours in nitrogen environment

Carbonization of the SU-8

The Resistive Properties of Thin Carbon Films from Pyrolized SU-8

Justin Little

Department of Mechanical and Aerospace EngineeringUniversity of California, Irvine

Funded by the National Science Foundation

Mentors: Professor Richard Nelson

Professor John Larue

Support: Allen Kine and Hideo Morita

My Job…

1. Design Kelvin-Bridge

• Acquire Materials

• Draw Design

• Determine Tolerances

• Construct Final Product

2. Use Kelvin-Bridge

• Acquire Data

• Determine Accuracy

The Resistive Properties of Thin Carbon Films from Pyrolized SU-8

Justin Little

Department of Mechanical and Aerospace EngineeringUniversity of California, Irvine

Funded by the National Science Foundation

Mentors: Professor Richard Nelson

Professor John Larue

Support: Allen Kine and Hideo Morita

How does a Kelvin Bridge work?

Ohm’s Law: V = IR

Therefore… R = V/I

The Resistive Properties of Thin Carbon Films from Pyrolized SU-8

Justin Little

Department of Mechanical and Aerospace EngineeringUniversity of California, Irvine

Funded by the National Science Foundation

Mentors: Professor Richard Nelson

Professor John Larue

Support: Allen Kine and Hideo Morita

Finding the Resistivity (ρ)…

R lA

ρ = Resistivity

R = Resistance across strip

l = length of strip

A = Cross-Sectional Area

The Resistive Properties of Thin Carbon Films from Pyrolized SU-8

Justin Little

Department of Mechanical and Aerospace EngineeringUniversity of California, Irvine

Funded by the National Science Foundation

Mentors: Professor Richard Nelson

Professor John Larue

Support: Allen Kine and Hideo Morita

Design Requirements…

• The Kelvin Bridge must make measurements in temperatures between room and 260 °C

• It should achieve an accuracy within 0.1% of expected values

• It needs to demonstrate a high level of repeatability and reliability

• Safety

The Resistive Properties of Thin Carbon Films from Pyrolized SU-8

Justin Little

Department of Mechanical and Aerospace EngineeringUniversity of California, Irvine

Funded by the National Science Foundation

Mentors: Professor Richard Nelson

Professor John Larue

Support: Allen Kine and Hideo Morita

Design Process…

1. Incorporate requirements into an initial design

2. Evaluate design and look at options

3. Select materials based on the requirements (Teflon, Bakelite, Aluminum)

4. Draw out plans in AutoCAD

5. Determine tolerances

The Resistive Properties of Thin Carbon Films from Pyrolized SU-8

Justin Little

Department of Mechanical and Aerospace EngineeringUniversity of California, Irvine

Funded by the National Science Foundation

Mentors: Professor Richard Nelson

Professor John Larue

Support: Allen Kine and Hideo Morita

Housing Components…

Aluminum Heating Mass Teflon Block Aluminum Block Copper Contacts

The Resistive Properties of Thin Carbon Films from Pyrolized SU-8

Justin Little

Department of Mechanical and Aerospace EngineeringUniversity of California, Irvine

Funded by the National Science Foundation

Mentors: Professor Richard Nelson

Professor John Larue

Support: Allen Kine and Hideo Morita

Complete Design…

The Resistive Properties of Thin Carbon Films from Pyrolized SU-8

Justin Little

Department of Mechanical and Aerospace EngineeringUniversity of California, Irvine

Funded by the National Science Foundation

Mentors: Professor Richard Nelson

Professor John Larue

Support: Allen Kine and Hideo Morita

• Type K Thermocouple

• Two heated dissimilar metals joined at the ends create a continuous current

• Alumel and Chromel

• Omega Thermometer

Temperature Measurements…

The Resistive Properties of Thin Carbon Films from Pyrolized SU-8

Justin Little

Department of Mechanical and Aerospace EngineeringUniversity of California, Irvine

Funded by the National Science Foundation

Mentors: Professor Richard Nelson

Professor John Larue

Support: Allen Kine and Hideo Morita

Temperature Measurements…

The Resistive Properties of Thin Carbon Films from Pyrolized SU-8

Justin Little

Department of Mechanical and Aerospace EngineeringUniversity of California, Irvine

Funded by the National Science Foundation

Mentors: Professor Richard Nelson

Professor John Larue

Support: Allen Kine and Hideo Morita

The Outcome…

The Resistive Properties of Thin Carbon Films from Pyrolized SU-8

Justin Little

Department of Mechanical and Aerospace EngineeringUniversity of California, Irvine

Funded by the National Science Foundation

Mentors: Professor Richard Nelson

Professor John Larue

Support: Allen Kine and Hideo Morita

The Outcome…

The Resistive Properties of Thin Carbon Films from Pyrolized SU-8

Justin Little

Department of Mechanical and Aerospace EngineeringUniversity of California, Irvine

Funded by the National Science Foundation

Mentors: Professor Richard Nelson

Professor John Larue

Support: Allen Kine and Hideo Morita

The Outcome…

The Resistive Properties of Thin Carbon Films from Pyrolized SU-8

Justin Little

Department of Mechanical and Aerospace EngineeringUniversity of California, Irvine

Funded by the National Science Foundation

Mentors: Professor Richard Nelson

Professor John Larue

Support: Allen Kine and Hideo Morita

The Outcome…

The Resistive Properties of Thin Carbon Films from Pyrolized SU-8

Justin Little

Department of Mechanical and Aerospace EngineeringUniversity of California, Irvine

Funded by the National Science Foundation

Mentors: Professor Richard Nelson

Professor John Larue

Support: Allen Kine and Hideo Morita

Final Precautions…

The Resistive Properties of Thin Carbon Films from Pyrolized SU-8

Justin Little

Department of Mechanical and Aerospace EngineeringUniversity of California, Irvine

Funded by the National Science Foundation

Mentors: Professor Richard Nelson

Professor John Larue

Support: Allen Kine and Hideo Morita

Setbacks…

• Available wire only withstands 200 °C

• Pyrolysis tube was inoperable for a week

• Empty forming gas tank

• Time constraints

The Resistive Properties of Thin Carbon Films from Pyrolized SU-8

Justin Little

Department of Mechanical and Aerospace EngineeringUniversity of California, Irvine

Funded by the National Science Foundation

Mentors: Professor Richard Nelson

Professor John Larue

Support: Allen Kine and Hideo Morita

Results…

The Resistive Properties of Thin Carbon Films from Pyrolized SU-8

Justin Little

Department of Mechanical and Aerospace EngineeringUniversity of California, Irvine

Funded by the National Science Foundation

Mentors: Professor Richard Nelson

Professor John Larue

Support: Allen Kine and Hideo Morita

Thanks…

• National Science Foundation

• Professor Richard Nelson and Professor John LaRue

•Allen Kine

•Hideo Morita and Farzaneh Bakhshi

•Ted Ediss