stretch
Undergraduate Category: Engineering and Technology Degree Level: BS Chemical Engineering Abstract ID# 257
Novel Elastomer-Assisted Manufacturing Process For Extending Optical Lithography Resolution Limits Jake Rabinowitz & Yuqing Liu, Northeastern University Faculty Advisor: Sivasubramanian Somu
Abstract
Employing this technique, we have successfully reduced 200 μm features (present in the optical mask) by over 10 times, fabricated metallic features as small as 8 μm from 20 μm features (in the optical mask), and developed in photoresist features as small as 2 μm from 5 μm features (in the optical mask).
[1] Apply tensile stress (stretch); Stretching Factor of 2 depicted
[2] Insert and coat with photoresist
Advantages: • Low cost • Fast process time Disadvantages: • Large resolution limit
Dip-pen Nanolithography5,6 Advantages: • Small resolution limit • Does not introduce harmful chemistry
[5] Deposit gold and remove photoresist
8 x1 x2 y1 y2
6
• Features elongate in direction perpendicular to applied stretching (coupling)
4 2 0 1
Metal features with reduced width
Results
Advantages: • Small resolution limit • Large functional area Disadvantages: • Incompatibility • Low feature yield
Disadvantages: • Serial process • High cost • Slow process time
• As elastomer is stretched further, feature reduction occurs to greater extent
2
3
4
5
Applied Stretching Factor
Conclusion
Nanoimprint Lithography1,4
Advantages: • Small resolution limit Disadvantages: • Serial process • High cost
Elastomer after exposure; feature width = “X”
Unstretched Elastomer; length returns to “L” and feature width reduces to “0.5X”
Customized holder maintains elastomer in stretched state during application of photoresist (purple)
Electron-beam Lithography2,3
[4] Release tensile stress (unstretch); Feature Decrement Factor of 2 depicted
Key observations:
10
Elastomer (blue) of length L
2L
Background Optical Lithography1,2
|-------------------------------------|
|--------------------------------------------------------------------|
• Fabrication of sub-micron features using optical lithography • Designed for flexible, stretchable substrates • Low cost, high reliability • Large functional area, short process time • Improves upon commercially-established technique
12
[3] Expose photoresist through optical mask to create features
Optical Lithography
Advantages offered by “Elastomerassisted manufacturing”:
Non-Linear Response to Stretching Feature Decrement Factor
We present a novel “Elastomer-assisted manufacturing” process which leverages the unique flexibility and stretchability of elastomers to extend the traditional resolution limits of optical lithography.
Methodology
In conclusion, we have presented for the first time a novel technique for extending the limits of optical lithography and fabricating features on elastomers and other flexible substrates.
Direction of Stretching 197 μm
Benefits of employing elastomer-assisted manufacturing: • • • •
5.15 μm
19.4 μm
204 μm
5.74 μm
20.3 μm
Low cost with fast processing time and high reliability Easily scalable to cover large functional areas Nanometer-scale resolution limit Designed for flexible, stretchable substrates
The following results have been achieved thus far:
Goals • Fabricate sub-micron features • Consistently reduce feature size by over 10x • Achieve isotropic feature reduction • Determine critical stretching limit
Long-term Applications and Possibilities:
200 μm feature; 4x stretched
20 μm feature; 2x stretched
5 μm feature; 2x stretched
iPad that stretches into a TV
• • • •
Feature reduction as far as 10 times Fabricating metallic features as small as 8 μm from an optical mask of 20 μm resolution Fabricating features in photoresist as small as 2 μm from an optical mask of 5 μm resolution Quantifying and leveraging the elastomer’s nonlinear and coupled responses to the applied stretching forces
26.8 μm
References & Acknowledgements
2.26 μm
7.92 μm
1. 2. 3.
Cancer treatment that wraps around a tumor
Lighter, more flexible e-paper
Google Glass that is worn like a contact lens
270 μm
27 μm metallic feature; 8x feature reduction
33.7 μm
8 μm metallic feature; 2.5x feature reduction
8.48 μm
2 μm feature in PR; 2.5x feature reduction
George J. Kostas Center for High-rate Nanomanufacturing, "NEU Aeroweb," Northeastern University, Boston. J. Rabinowitz, Optical Lithography Image, Boston: Center for High-rate Nanomanufacturing, 2014. AnalySys Sciences, "E-beam lithography," [Online]. Available: http://analysciences.com/tools-fornanotechnology/npgs/. 4. W. Y. Fu and H. W. Choi, "Nanosphere Lithography for Nitride Semiconductors," in Lithography, InTech, 2010. 5. NIST, "Atomic Force Microscope 2: Digital Instruments/Veeco Dimensioni 3000," 26 January 2010. [Online]. Available: http://www.nist.gov/cnst/nanofab/nanofab_afm3000.cfm. 6. D. S. Ginger and et. al, "The Evolution of Dip-pen Nanolithography," Angewandte Chemie, vol. 43, no. 1, 2004. I would like to thank my research advisor Sivasubramanian Somu for the guidance and insight he has provided me. The experiments were conducted at the George J. Kostas Nanoscale Technology and Manufacturing Research Center at Northeastern University. I would like to thank CHN staff members David McKee and Scott McNamara for the technical assistance and training they have provided me. I would like to thank NU graduate student Yuqing Liu for the groundwork he did on the project.
Novel Elastomer-Assisted Manufacturing Process For Extending Optical Lithography Resolution Limits Jake Rabinowitz & Yuqing Liu, Northeastern University Faculty Advisor: Sivasubramanian Somu
Abstract
Employing this technique, we have successfully reduced 200 μm features (present in the optical mask) by over 10 times, fabricated metallic features as small as 8 μm from 20 μm features (in the optical mask), and developed in photoresist features as small as 2 μm from 5 μm features (in the optical mask).
[1] Apply tensile stress (stretch); Stretching Factor of 2 depicted
[2] Insert and coat with photoresist
Advantages: • Low cost • Fast process time Disadvantages: • Large resolution limit
Dip-pen Nanolithography5,6 Advantages: • Small resolution limit • Does not introduce harmful chemistry
[5] Deposit gold and remove photoresist
8 x1 x2 y1 y2
6
• Features elongate in direction perpendicular to applied stretching (coupling)
4 2 0 1
Metal features with reduced width
Results
Advantages: • Small resolution limit • Large functional area Disadvantages: • Incompatibility • Low feature yield
Disadvantages: • Serial process • High cost • Slow process time
• As elastomer is stretched further, feature reduction occurs to greater extent
2
3
4
5
Applied Stretching Factor
Conclusion
Nanoimprint Lithography1,4
Advantages: • Small resolution limit Disadvantages: • Serial process • High cost
Elastomer after exposure; feature width = “X”
Unstretched Elastomer; length returns to “L” and feature width reduces to “0.5X”
Customized holder maintains elastomer in stretched state during application of photoresist (purple)
Electron-beam Lithography2,3
[4] Release tensile stress (unstretch); Feature Decrement Factor of 2 depicted
Key observations:
10
Elastomer (blue) of length L
2L
Background Optical Lithography1,2
|-------------------------------------|
|--------------------------------------------------------------------|
• Fabrication of sub-micron features using optical lithography • Designed for flexible, stretchable substrates • Low cost, high reliability • Large functional area, short process time • Improves upon commercially-established technique
12
[3] Expose photoresist through optical mask to create features
Optical Lithography
Advantages offered by “Elastomerassisted manufacturing”:
Non-Linear Response to Stretching Feature Decrement Factor
We present a novel “Elastomer-assisted manufacturing” process which leverages the unique flexibility and stretchability of elastomers to extend the traditional resolution limits of optical lithography.
Methodology
In conclusion, we have presented for the first time a novel technique for extending the limits of optical lithography and fabricating features on elastomers and other flexible substrates.
Direction of Stretching 197 μm
Benefits of employing elastomer-assisted manufacturing: • • • •
5.15 μm
19.4 μm
204 μm
5.74 μm
20.3 μm
Low cost with fast processing time and high reliability Easily scalable to cover large functional areas Nanometer-scale resolution limit Designed for flexible, stretchable substrates
The following results have been achieved thus far:
Goals • Fabricate sub-micron features • Consistently reduce feature size by over 10x • Achieve isotropic feature reduction • Determine critical stretching limit
Long-term Applications and Possibilities:
200 μm feature; 4x stretched
20 μm feature; 2x stretched
5 μm feature; 2x stretched
iPad that stretches into a TV
• • • •
Feature reduction as far as 10 times Fabricating metallic features as small as 8 μm from an optical mask of 20 μm resolution Fabricating features in photoresist as small as 2 μm from an optical mask of 5 μm resolution Quantifying and leveraging the elastomer’s nonlinear and coupled responses to the applied stretching forces
26.8 μm
References & Acknowledgements
2.26 μm
7.92 μm
1. 2. 3.
Cancer treatment that wraps around a tumor
Lighter, more flexible e-paper
Google Glass that is worn like a contact lens
270 μm
27 μm metallic feature; 8x feature reduction
33.7 μm
8 μm metallic feature; 2.5x feature reduction
8.48 μm
2 μm feature in PR; 2.5x feature reduction
George J. Kostas Center for High-rate Nanomanufacturing, "NEU Aeroweb," Northeastern University, Boston. J. Rabinowitz, Optical Lithography Image, Boston: Center for High-rate Nanomanufacturing, 2014. AnalySys Sciences, "E-beam lithography," [Online]. Available: http://analysciences.com/tools-fornanotechnology/npgs/. 4. W. Y. Fu and H. W. Choi, "Nanosphere Lithography for Nitride Semiconductors," in Lithography, InTech, 2010. 5. NIST, "Atomic Force Microscope 2: Digital Instruments/Veeco Dimensioni 3000," 26 January 2010. [Online]. Available: http://www.nist.gov/cnst/nanofab/nanofab_afm3000.cfm. 6. D. S. Ginger and et. al, "The Evolution of Dip-pen Nanolithography," Angewandte Chemie, vol. 43, no. 1, 2004. I would like to thank my research advisor Sivasubramanian Somu for the guidance and insight he has provided me. The experiments were conducted at the George J. Kostas Nanoscale Technology and Manufacturing Research Center at Northeastern University. I would like to thank CHN staff members David McKee and Scott McNamara for the technical assistance and training they have provided me. I would like to thank NU graduate student Yuqing Liu for the groundwork he did on the project.
