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Introduction
Greetings, fellow traveler! This page is part of a larger project, with the ultimate goal of creating a Josephson Junction Voltage Standard at OV. Information on this kind of standard can be found on the Josephson Junction Voltage Standard- Project page.
OV has for a long time been renown for it's skilled, somewhat eccentric members, and has a long standing tradition of interesting projects.
A silicon CMOS process is while on one hand far more useful, a lot more complex and harder to acheive good process til
Most basic superconducting circuits can be made with little more than a
Deposition: All preformed with E-Beam system in mor di.
- All materials in question are easily deposited with an electron beam
- Substrate movement only required for
Even though
Lithography: Nah, PL needs photoresist, etching and exposure. Use Laser cut stainless steel pcb stencils from china instead! Physical masking is way
at OV can not only do basic deposition, but microcircuit fabrication and superconductor experimentation. I (HT) do not know of any simpler process we might use to accomplish this, the costs involved are minimal and virtually no additional equipment is required.
It will however be potato-quality and cause nanolab engineers to roll of their chairs laughing.
Stage 1: Simple Nb film deposition, measurements and basic optimization.
Fulfillment needs
- Mor Di:
- Operational Water Cooling System
- Operational Power System
- Largely Done
- Operational Helium Cooler
- Has been thoroughly inspected
- Has been power tested
- Has been operationally verified
- Has NOT had performance verification
- May need Helium Fill
- Operational Control System
- Almost completely verified. Timers, setpoints and program cycles all operate as normally intended.
- Has been through many dry runs already
- Hasn't done entire Cycle
- Operational E-Beam Supply
- Not yet powered up
- Has had multiple issues w/ either scan controls or disrupted beam optics
- Working Chamber Mechanics
- Pneumatics issues must be investigated.
- Functioning Quartz Balance
- Other Equipment
- Multimeter
- Repeatable Kelvin Probes
- Multimeter
- Supplies
- >2 Pyrolytic Carbon Crucibles, : ~€180 each from kjlc
- Pure Nb Pellets; €102.00 for 50g from KJLC
- AlOx Pellets/shards
- Nb Pellets, €102.00 for 50g from kjlc: https://www.lesker.com/newweb/deposition_materials/depositionmaterials_evaporationmaterials_1.cfm?pgid=nb1
- SiO2 Pellets, €28 for 100g from kjlc: https://www.lesker.com/newweb/deposition_materials/depositionmaterials_evaporationmaterials_1.cfm?pgid=si2
- 2" Silicon Wafers: 60kr each from NTNU Nanolab Supplies
Important measurements
MUSTs
- Chamber temperatures
- Water temperatures
- Substrete Temperatures
- Chamber Pressure
- Deposition Rate
Nice's
- Approximate Film Thickness
Requirements
- OV
Useful knowledge
- A Characterized deposition rate curve, assuming some repeatability efforts are taken
- A full operational verification of Mor Di: All systems now both known and tested to be operational.
Stage 2: Recipe Design; Film Inspection.
After having Verified the deposition process in Stage 1, A recipe for Nb/AlOx- epitaxy can now be designed. Several test depositions are required and need careful stydying, the electron microscope may come very much in handy for this.
Proper lithography, process control and maybe NbN- sputtering to better layer adhesion and superconducting properties.
Will probably need to access nanolab and have some backing from Timini Labs or a technician, but not an unrealistic step up.
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Stage 3: Basic Lithography
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Stage 3A: (Photo)mask Application
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Stage 3B: Development
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Stage 3C: Etching
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Stage 4: Junction Testing.
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Method for preparing soldered pad connections to Nb- Pads with indium solder & Low temp soldering iron: