1. Department of Mechanical Engineering
Air Bubble Defects in Dispensing
Nanoimprint Lithography
University of Michigan
Student：Nan Li Instructor：Xiaogan Liang

2. PART 01
Introduction
PART 02
Objective
PART 03
Approach
PART 04
Conclusion

3. PART 01
Introduction
Challenge
Advantage

4. 4
Introduction
Objective
Approach
Conclusion
Introduction
Key Advantage
Nanoimprint lithography: High resolution

5. 5
Introduction
Objective
Approach
Conclusion
Introduction
Dispensing based NIL
Challenge: Air bubble defects

6. 6
Introduction
Objective
Approach
Conclusion
Introduction
Dispensing based NIL
Air is trapped during merging.
Air Bubble Formation

7. PART 02
Objective
Dynamic Behavior

8. 8
Introduction
Objective
Approach
Conclusion
Objective
DissolutionStage 1: Stage 2:
Previous
Study
Dynamic Behavior
Experimental Study
Theoretical Study

9. 9
Introduction
Objective
Approach
Conclusion
Objective
Stage 1: Dissolution
Experimental Study
Air bubble dissolve with time.
Not reach 0

10. 10
Introduction
Objective
Approach
Conclusion
Objective
Air Bubble Defects
Nano-Scale

11. 11
Introduction
Objective
Approach
Conclusion
Objective
Continue here

12. 12
Introduction
Objective
Approach
Conclusion
Objective
DissolutionStage 1: RelaxationStage 2:
Our Study
Dynamic Behavior
Theoretical Study
Simulation Study

13. 13
Introduction
Objective
Approach
Conclusion
Objective
Hypothesis
Surface Energy Relaxation

14. PART 03
Approach
Theoretical
Simulation

15. 15
Introduction
Objective
Approach
Conclusion
Approach
Stage 2: Relaxation
Theoretical Study
Air bubble will spreads since unbalanced surface tension.

16. 16
Introduction
Objective
Approach
Conclusion
Approach
Stage 2: Relaxation
Theoretical Study
Air bubble will stop spreads, stay equilibrium position, lowest surface energy.

17. 17
Introduction
Objective
Approach
Conclusion
Approach
Stage 2: Relaxation
Theoretical Study
Dissolution

18. 18
Introduction
Objective
Approach
Conclusion
Approach
Animation
Experimental Study

19. 19
Introduction
Objective
Approach
Conclusion
Approach
Energy Evaluation
Simulation Study
0.0001s 0.008s
0.01s 0.02s

20. 20
Introduction
Objective
Approach
Conclusion
Approach
Animation
Simulation Study
0.03s 0.1s
0.03s 0.4s

21. PART 04
Conclusion

22. 22
Introduction
Objective
Approach
ConclusionConclusion
D-NIL
Challenge
Study
Result
Simulation
Theoretical and simulation
Support hypothesis
Dynamic behavior
Hypothesis of surface energy
relaxation stage
Air Bubble Defects
Air trapped in the resist
High Resolution
Nano-structure in nm scale
Conclusion

23. 23
Introduction
Objective
Approach
ConclusionConclusion
X. Liang, H. Tan, Z. Fu, and S. Y. Chou, “Air bubble formation and dissolution
in dispensing nanoimprint lithography,” Nanotechnology, pp. 025303–
025303, 2006.
“ramé-hart Contact Angle,” ramé-hart Contact Angle. [Online]. Available
at: http://www.ramehart.com/contactangle.htm. [Accessed: Feb-2015].
M. C. Weinberg, “Surface tension effects in gas bubble dissolution and
growth,” Chemical Engineering Science, pp. 137–141.
Reference

24. Thank You
Instructor：Xiaogan Liang Partner: Xiaobai Ma Student：Nan Li
Welcome Question!

25. PART 05
Backup

26. 26
Significance
Introduction
Objective
Approach
Conclusion
Approach
Stage 2: Relaxation
Theoretical Study
𝛾 𝐿𝑆: the liquid-solid interfacial free energy
𝛾 𝐿𝐺: the liquid-gas interfacial free energy
𝛾 𝐺𝑆 : gas-solid interfacial free energy
𝜃1:the contact angel

27. 27
Significance
Introduction
Objective
Approach
Conclusion
Approach
Dimensional
Analysis
Scale-up Ratio:
nm to mm
CFD-Simulation
Geometry
Key Parameters
Animation
Simulation Data
Evaluation
Key Technology
Simulation Study

28. 28
Significance
Introduction
Objective
Approach
Conclusion
Approach
Simulation Geometry
Axisymmetric

29. 29
Significance
Introduction
Objective
Approach
Conclusion
Approach
Dimensional Analysis
Assume 𝜌 𝑚 = 𝜌 𝑝, 𝐿 𝑚 = 1 𝑚𝑚,𝐿 𝑝 = 100 𝑛𝑚, since
𝜇 𝑚
𝜇 𝑝
= 100
𝜇 𝑚
𝜇 𝑝
=
𝜌 𝑚 𝐿 𝑚
𝜌 𝑝 𝐿 𝑝
𝜇 = 𝑓 𝜌, 𝑉, 𝐿, σ
𝜌𝑉𝐿
𝜇
= 𝑔(
∆𝑃
1
2
𝜌𝑉2
,
𝜌𝑉2 𝐿
𝜎
) 𝑅𝑒 = 𝑔( 𝐸𝑢, 𝑊𝑒)
𝑅𝑒 𝑚 = 𝑅𝑒 𝑝, 𝑊𝑒 𝑚 = 𝑊𝑒 𝑝
Scaling Factor
Simulation Study

30. 30
Significance
Introduction
Objective
Approach
Conclusion
Approach
Simulation Parameters
Settings Parameters
General Axisymmetric, 1mm
Models
Volume of Fluid
Phase Interaction: Surface tension coefficient: 0.072
Laminar
Materials
Bubble: Air
Resist: Water-liquid
Viscosity [kg/m-s]:0.00179, 0.1003
Boundary
conditions
Upper wall contact angle:160
Upper wall contact angle:160
Pressure outlet: water backflow fraction=1
Solution Method Simple C
Scaled up by 100
Simulation Study