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FABRICATING MICROSCALE PATTERNING BY CHEMICAL LIFT-OFF LITHOGRAPHYROBERT ESPINOZA, DR. WEI-SSU LIAO LABDEPARTMENT OF CHEMISTRY2016-8-11

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REAL WORLD APPLICATIONS

• Chips

• Devices

• Sensors

https://www.a-star.edu.sg/Portals/0/media/Press%20Release/microfluidics-img.jpghttp://ichef-1.bbci.co.uk/news/660/media/images/78547000/jpg/_78547661_78547660.jpg

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EXPERIMENTAL GOALS

• Microdroplet array fabrication

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INTRODUCTION: WHAT IS CHEMICAL LIFT-OFF LITHOGRAPHY?• Micro-/nanoscale etching

• Polydimethylsiloxane (PDMS)

• Self assembled monolayer (SAM)

“Double-Sided Opportunities Using Chemical Lift-Off Lithography”, Liao WS*,  Accounts of Chemical Research (2016)

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CHEMICAL LIFT-OFF VS OTHER LITHOGRAPHY TECHNIQUES• Soft Lithography• Electron Beam Lithography

Hsia, K. J.; Huang, Y.; Menard, E.; Park, J.-U.; Zhou, W.; Rogers, J.; Fulton, J. M., Appl. Phys. Lett. 2005, 86, 154106http://www.stoner.leeds.ac.uk/Research/TutFab

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OVERALL EXPERIMENTAL PROCESS

Gold Wafer with Hydrophillic

SAMPerform CLL

Drop ReagentsInto Array

Hydrophobic PFDT

Gold Wafer

Prep SAM Overnight

Place PDMS Stamp for

2 Hours

Backfill into CLL region withPFDT for 1 hour

Wash Wafer with Ethanol

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EXPERIMENTAL PROCESSES

• Clean room processes: • PDMS fabrication

• Photolithography wafers

• Making PDMS stamp

Exposed

PDMS：A:B=10:1

Develop

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CLEAN ROOM EXPERIMENTAL DATA

Photoresist Pillars

PDMS Holes

Photoresist Lines

Photoresist Holes

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EXPERIMENTAL PROCESSES• Laboratory processes:

• Developing SAM

• Oxygen Plasma

• Performing CLL

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LABORATORY EXPERIMENTAL DATA

“Subtractive Patterning via Chemical Lift-Off Lithography” Liao WS, Science 337 (2012): 1517-1521

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LABORATORY EXPERIMENTAL DATALine 42 Micron Circle 5 Micron Square

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FUTURE RESEARCH• Improving the Microdroplet Array

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CONCLUSION

• Many applications

• More accessible lithography

• Superior resolution

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ACKNOWLEDGEMENTS

Dr. LiaoHsiao-Yuan (Mimi)National Taiwan UniversityMinistry of ScienceUniversity of California Education Abroad ProgramUniversity of California, Riverside

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THANK YOUQUESTIONS?