NanoFab Trainer Update
Nick Reeder, March 1, 2013
Updates to User Interface
• When starting the program or starting a new
file, user is now prompted to specify the
width of the design.
– This width is saved when saving work to file, and
is restored when opening an existing file.
• Height of display window is now auto-scaled
to show two microns above top of wafer
structure (unless user has selected View
Equal Horizontal and Vertical Scales).
Updates to User Interface (Cont.)
• To improve readability, added units and
background color to look-up tables 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 Code: Combining Layers
• New code combines adjacent layers of the
same material.
– Need this to correctly handle processes that
depend on total layer thickness, such as thermal
oxidation and UV exposure of photoresist.
Updates to Thermal Oxidation Code
• SiO2 now grows down into the Si (45%) and
upward from the original surface (55%).
• Assumption: Si is oxidized to SiO2 only where
either Si is exposed to the surface, or Si is
directly under a layer of SiO2 that is exposed
to the surface. A layer of any other material
above the Si or SiO2 prevents oxidation.
Updates to Thermal Oxidation Code
(Cont.)
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Uses Deal-Grove model to compute oxide
thickness based on time, temperature, initial
oxide thickness, and environment (wet or dry).
Assumes <100> crystal orientation. Checked
against online calculator at BYU.
Not fully functional; it works if the initial oxide
thickness is constant over the entire wafer, but
doesn’t correctly handle variations in initial
oxide thickness.
View > Oxidation Rate Curves lets user see
effect of varying the input parameters.
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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