Asymmetric fluid-structure dynamics in nanoscale imprint lithography

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Chapter 7: Closing Remarks7.1 SUMMARY OF RESEARCHThis research has encompassed a broad range of areas including analyticalmodeling, numerical simulations, and experimental analysis. It has alsoincorporated a medley of software/hardware issues and spectral analysis. Byinterpreting the analytical models, numerical simulations, and experimentalresults, it has been shown that the Reynolds equations for squeeze film dampingis a valid and useful tool for understanding the dynamics of the mechanicalsystems in SFIL.The fluid pressure plays a significant role to orient the passively compliantstages used in the multi-imprint stepper and the single imprint machines. It hasbeen shown that the pressure tends to correct the angular misalignments bygenerating a damping torque and the pressure asymmetry cannot be ignored.Thus, the original intent of the passive stage designs has been proven to work.The passive stages self-correct due to the coupling between the mechanicalsystem and the liquid etch barrier. Although presence of the etch barrier aides incorrecting the misalignment, it also limits the rate at which imprinting can bedone since, thinner base layers require more time to achieve. However, with anappropriate control scheme, based on a two s-curve motion profile, this problemcan be solved. Furthermore, the theoretical and measured forces can be achievedby the actuation systems currently implemented.An additional contribution of this research work has been the applicationof a real-time gap-sensing tool in measuring the film thickness of the fluid duringthe squeezing process. In developing an active stage system to perform SFIL, this99
is a major milestone. The next step would be to use this information to performreal-time control of the base layer thickness and template orientation.Step and Flash imprint lithography has the potential to become amanufacturing technology within several years. It offers high-resolutioncapability, high-throughput, and cost effectiveness. Much progress has beenmade in the way of appropriate chemistries for the etch barrier, transfer layers,etc. Significant work has been done to understand the kinematics of the machinesnecessary to perform imprinting. Several imprinting prototypes have beendeveloped and are currently being used to meet the ongoing challenges in theresearch. There are several milestones that must be surpassed before SFIL canbecome a full manufacturing technology. The following sections attempt toilluminate the reader on these specific tasks.7.2 FUTURE WORK7.2.1 Numerical Solution to the Generalized Reynolds EquationIn deriving the analytical solution to the pressure distribution, thetopography of the template has been neglected. Also, three-dimensional effectscould be significant enough to warrant a full numerical solution to the generalizedReynolds equation, which would include topography, growth of the fluidboundary, and angle of inclination as well as lateral motions. A practical issue inmodeling with the generalized solution to the Reynolds equation is computationalcomplexity since the solution would need to be numerical as opposed toanalytical. Complete fluid-structure coupling may require a high number offloating-point operations and complex numerical algorithms to solve for the100
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Asymmetric Fluid-StructureDynamics
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AcknowledgementsFirst of all, I wou
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Table of ContentsList of Tables ...
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6.2.3 Control Software ............
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List of FiguresFigure 1.1 Optical m
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Figure 6.9 Force due to fluid press
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The exponential escalation in the c
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1.2.1 Optical Lithography Process O
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patterns to the desired specificati
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1.3 STEP AND FLASH IMPRINT LITHOGRA
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transferlayerwaferStep 1: Spin-coat
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the etch barrier fluid has an infin
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Researchers at the University of Te
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stage development. Design requireme
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minimum and maximum base layer thic
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square plate with fluid completely
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7. The fluid is assumed incompressi
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⎛ ∂ ⎞⎜τdz ⎟dxdy⎝+ τ
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where V 1 and V 2 correspond to U 1
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ddx⎛⎜h⎝3dp ⎞ ∂h⎟ = 12µ
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dhdtLzhθh αh βxx αx = 0 x βFig
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C2hhtanθ2 21= αxαxβxαxβ( ) (
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⎛⎜ hD⎜⎝6C ⎞1tanθ⎟24µh
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at the plate edges. Freeland obtain
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For the case of 10 psi of pressure,
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are the same as the width of the tr
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orientation stages relative to the
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Wafer ChuckAir SolenoidMounting Pla
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The one degree-of-freedom template
Page 61 and 62: Figure 3.7 Initial and final desire
Page 63 and 64: 7645321Figure 3.8 Active stage prot
Page 65 and 66: Chapter 4: Real-Time Gap Sensing Vi
Page 67 and 68: R( λ)( 4πnd/ λ)2 2 −2αd−αd
Page 69 and 70: Rate Monitoring and is adapted for
Page 71 and 72: 10090807060PSD504030201000 500 1000
Page 73 and 74: the multi-imprint and active stage
Page 75 and 76: 5.2.2 Composite Stiffness and Dampi
Page 77 and 78: ( )2πR−1.5clamping length of 1.5
Page 79 and 80: 65actuator height, micron432100 0.1
Page 81 and 82: time marching is required to minimi
Page 83 and 84: 5.4 SQUEEZE FILM DYNAMICS OF INCLIN
Page 85 and 86: force, lb504540353025201510500 0.05
Page 87 and 88: improve upon these results by tunin
Page 89 and 90: Again, Figure 5.12 shows that a bas
Page 91 and 92: optically flat quartz plate coated
Page 93 and 94: optic probe was illuminated with a
Page 95 and 96: Figure 6.3 Screenshot of control so
Page 97 and 98: 6.3 EXPERIMENTAL PROCEDUREExperimen
Page 99 and 100: film thickness, nm40003800360034003
Page 101 and 102: Figure 6.6 shows that the force due
Page 103 and 104: similar. In Figures 6.7 and 6.8, th
Page 105 and 106: 500045004000film thickness, nm35003
Page 107 and 108: Figure 6.13 shows the force-time pl
Page 109 and 110: ⎛ n ⎞in the FFT that is not ind
Page 111: when measuring thin layers in the r
Page 115 and 116: 7.2.4 Control schemeThe ultimate go
Page 117 and 118: Assuming the liquid perfectly wets
Page 119 and 120: ase h (for a semi-circular notch,h
Page 121 and 122: Chou, S. Y., P .R. Krauss, and P. J
Page 123 and 124: Tripp, J. H. 1983. Surface roughnes
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