1. Experiment 5
Ravi.K.Reddy

2. Ravi.K.Reddy-Fab Course1
Outline
Everything you already learnt +
NEW pictures
11/22/2018
Ravi.K.Reddy-Fab Course1

3. Ravi.K.Reddy-Fab Course1
What you will Learn
What is Fabrication
Lithography
How to Fabricate
Molds
Microelectrode Arrays
Learn to use
Spin Coater
Mask Aligner
ssls.nus.edu.sg/.../ limint/beamline.htm
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Ravi.K.Reddy-Fab Course1

4. Ravi.K.Reddy-Fab Course1
Litho/Fabrication
PhotoLithoGraphy :Light- stone-writing
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Ravi.K.Reddy-Fab Course1
Lithoguru.com

5. Ravi.K.Reddy-Fab Course1
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Ravi.K.Reddy-Fab Course1

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Ravi.K.Reddy-Fab Course1

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Photo Mask
Design
Software
Manufacture
Quartz
Optics
Chrome coated
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Ravi.K.Reddy-Fab Course1

8. Ravi.K.Reddy-Fab Course1
Processing
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Ravi.K.Reddy-Fab Course1

9. Ravi.K.Reddy-Fab Course1
Substrate Cleaning
RCA Clean
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Ravi.K.Reddy-Fab Course1

10. Ravi.K.Reddy-Fab Course1
Primer HMDS
Hexa Methly Di Silazane
Good Adhesion
Dehydration
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Ravi.K.Reddy-Fab Course1

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Spin Coating
Use Data Sheets.
30% of the solvent is evaporated
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Ravi.K.Reddy-Fab Course1

12. Ravi.K.Reddy-Fab Course1
Spin Coating…
Striations
Edge Bead
Streaks
Comets
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Ravi.K.Reddy-Fab Course1

13. Ravi.K.Reddy-Fab Course1
Pre Bake :Soft Bake
To make the resist denser and evaporate the solvent
Hot plate still the best method compared to IR Lamps and Microwave heating
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Ravi.K.Reddy-Fab Course1

14. Ravi.K.Reddy-Fab Course1
Exposure
rapid-kinetics/spectros.html
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Ravi.K.Reddy-Fab Course1

15. Ravi.K.Reddy-Fab Course1
Expose/Develop Steps
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Ravi.K.Reddy-Fab Course1

16. More about Photo Resists
Dills Paramaters
Α=AM+B
A B M
A=(aPAC –aP)C0
B=Absorption of other components which don’t change there properties.
M=C/C0
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Ravi.K.Reddy-Fab Course1

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Optics
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Ravi.K.Reddy-Fab Course1

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Resist chemistry
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Ravi.K.Reddy-Fab Course1

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Early Photo Resists
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Ravi.K.Reddy-Fab Course1

20. Ravi.K.Reddy-Fab Course1
Azides
Negative Photo Resist
Problems
Issues with Contrast
Bridging
Swelling during development
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Ravi.K.Reddy-Fab Course1

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New Generation -DNQ
“Wave length Limited” resolution achieved for the first time here
Low Contrast
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Ravi.K.Reddy-Fab Course1

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Second Turning Point
PAG- Photo Acid Generators
High Contrast
Used in 193nm Tech.
Fast Reaction
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Ravi.K.Reddy-Fab Course1

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Chemistry Behind it
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Ravi.K.Reddy-Fab Course1

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Recap of Litho
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Ravi.K.Reddy-Fab Course1

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Aligners
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Ravi.K.Reddy-Fab Course1

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Mask Aligners
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Ravi.K.Reddy-Fab Course1

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Steppers
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Ravi.K.Reddy-Fab Course1

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ASML Stepper
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THE LATEST AND BEST
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Post Exposure Bake
Sometimes the Chemical Amplification is improved by PEB.
SU-8 forms cross linking here.
Data Sheets of the Resists define what temperature
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Developing the PR
Use developers provided by the company
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Hard Bake
To have better Etch resistance.
Required for process steps like Etch
Little bad for profiles of the resist
Reflow of the resist occurs
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Ravi.K.Reddy-Fab Course1

33. Ravi.K.Reddy-Fab Course1
Photo resist removal
Positive Resists
Acetone
Trichloroethylene (TCE)
Negative Resits
Methyl Ethyl Ketone (MEK)
Methyl isobutyl ketone (MIBK)
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Ravi.K.Reddy-Fab Course1

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Challenges
Complex Multidimensional Phase Space
Careful Optimization and tight process control
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Ravi.K.Reddy-Fab Course1

35. Ravi.K.Reddy-Fab Course1
Some Facts
Litho accounts to 1/3 of the entire cost
Close to 30 Masks used in each process.
Process Steps >250
New Masks- Cost $3M
CD determines the cost of the mask
NGL >$50 per stepper
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Ravi.K.Reddy-Fab Course1

36. Ravi.K.Reddy-Fab Course1
Experiment
Both Positive and Negative PR used.
Understand the process better-I hope.
THANK YOU
11/22/2018
Ravi.K.Reddy-Fab Course1