Transcript Nano-Fab Simulator Layout

NanoFab Trainer Update
Nick Reeder, April 5, 2013
Updates to User Interface
• Replaced look-up tables with graphs when
user selects any of the following:
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View > Evaporation Deposition Rates
View > Sputter Deposition Rates
View > Dry Etch Rates
View > Wet Etch Rates
• New menu item, Edit > Options, lets user
specify the height of the “airspace” displayed
above the wafer structure.
Updates to User Interface (Cont.)
• Added new Videos tab that lets user play
selected video in a Flash player window.
– Requires that user has Flash installed on
computer.
Updates to Thermal Oxidation Code
• Code now correctly handle variations in
initial oxide thickness (no longer assumes
that the initial oxide thickness is constant
over the entire wafer).
Updates to Develop Code
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Implemented two fictional developers:
– One removes exposed positive resist at 50 nm/sec,
and has no effect on unexposed positive resist or on
other materials.
– The other removes unexposed negative resist at
50 nm/sec, and has no effect on exposed negative
resist or on other materials.
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Need to replace with real developers and rates.
Code assumes develop is isotropic, like wet etch.
Is this right?
Photoresist Exposure
• Thinking about how to incorporate Andrew’s
C-code algorithm for computing photoresist
exposure into the trainer’s polygon-based
model.
• Proposal for a simplifying assumption: Since
resist solubility changes sharply with DNQ
concentration near the solubility threshold,
can we simply divide all photoresist into
“exposed” and “unexposed” regions after
computing DNQ concentration?
Proposal for Photoresist Exposure
Unexposed
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Exposed
Advantage: Much simpler to model than tracking the
DNQ concentration at many points inside the resist.
– Disadvantages:
• Inaccurately models development of partially exposed
resist.
• Doesn’t model cumulative effect of repeated
exposures.
To-Do List
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Implement look-up tables to compute deposition rates for CVD based on usersupplied pressure & temperature.
Populate evaporation and sputter look-up tables with values.
Fix expose, develop, polish code to compute depth from user-supplied values.
Continue writing bake code; need realistic values for S0 and .
In expose code, implement diffraction of UV in air and absorption within resist,
with dependence on solvent content from bake code.
Fix etch code so that (for photoresist) etch rates depend on solvent content from
bake code.
Fix spin-coat code so that resist does not adhere to underside of horizontal
surfaces.
Write new code for
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Lift-off
Clean
Profilometer
Write time-cost-quality code for all operations.
Write online help text.
Produce videos, photos, text for Tutorial tab.
Activity
Not started
Clean
Partial
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Spin coat
Simulation coding
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Bake
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Mask/Expose/Develop
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Evaporate
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Thermal oxidation
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CVD
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Sputter
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Wet etch
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Dry etch
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Lift off
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Polish
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Implant
Track time, cost, quality of each process
User -interface coding
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History with option to revert
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Save/open history files
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Edit colors
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User-defined materials
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Profilometer
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Producing embedded media (videos, photos, etc.)
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Testing
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Documentation
Complete
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