Metal Evaporation
(This page was transwikified from this Appropedia page).
Introduction
The metal evaporator is used to evaporate a variety of metals onto a substrate or film. A mask can be used to selectively coat a pattern onto a sample or multiple samples. Contacts for conductivity tests can be made by evaporating aluminium in two strips about 1mm apart.
Equipment Information
The metal evaporator is a 3 kW Thermionics RC-series 3-crucibles linear electron beam evaporator. Much of the system is custom designed. Available metals for evaporation: aluminium, gold, chromium, germanium, nickel, silicon oxide and titanium. The evaporation opening is about 2.75" by 1.75" so design masks accordingly. An ideal mask size would be around 3.25" by 2.25".
It is located in the Jackson Hall basement Cleanroom Anteroom. Pants and closed-toe shoes must be worn.
Protocol
To use the metal evaporator permission and training must be given from Dr. Knobel. He will also give you an account to book the evaporator.
The evaporator should have been left in a pumped down state upon arrival.
To vent:
- Close gate valve
- Open nitrogen valve and adjust regulator to ~20psi
- Open Newpro valve followed by "Vent" valve
Once fully vented (bell jar is loose and no air is escaping):
- Close Newpro valve
- Lift bell jar using switch (ensure it does not hit any parts on the way up)
- Change crucible if needed using the knob in the back (aluminium is crucible 3)
- Add in material to crucible if needed (should be filled 50-70% full with aluminium, if too much can overflow when melted)
- Program deposition settings
- PROG - change crucible # - adjust desired thickness
- XTAL - check crystal life (replace if above 25%)
- Clip samples onto mask and place mask over the evaporation opening
- Check if thermal or electron beam is hooked up (should be e-beam)
- Clean bottom of bell and ring with clean wipe and isopropyl alcohol
- Lower bell until motor stops
- Turn on roughing pump followed by R0, R1, R2 valves in order
- Turn on cooling water supply (red valve on back wall)
- Ensure black valve for e-beam water cooling is open
- Wait ~5 min until pressure reaches 30 mTorr (30-02 on screen)
- Close R2 and open gate valve (uses cryo pump)
- Close R0, R1 and shut off roughing pump
- Close "Vent" valve if not entering a gas during deposition
- Pump down until 2 x 10-6 Torr (~15 min)
Once fully pumped:
- Turn on black control (1 AMP setting), Thermionics control module
- Interlock light should be on, if not that means cooling water is not flowing
- Dial up current slowly (up to 0.3-0.4 mA)
- Turn on controller and adjust position of electron beam to centre of aluminium (make sure beam is not hitting crucible or other parts)
- Leave Amp and Frequency off for aluminium
- Once bright spot is visible and deposition rate is suitable (1-3 A/s) open shutter (press Open button on top right of program box)
- Shutter will automatically close upon completion of desired deposition thickness
- Dial off current power slowly
- Turn off controller and Thermionics power
- Let cool for 10-15 min
- Turn off water
- Close gate valve
- Turn off ion gauge
- Vent with nitrogen (same procedure as before)
- Open bell and remove samples
- Clean inside of bell jar if necessary
- Close bell
- Close Newpro valve
- Turn on roughing pump and open R0, R1, R2 in that order
- Once at 30m Torr, close R2
- Open gate valve, close R0,R1, turn off roughing pump
- Ensure ion guage and shutter box power are off, vent valve is closed
OTHER INFORMATION:
RECORD: Name, date and other info in logbook
Aluminium does not need to be weighed for invoice as it is cheap but gold or other metals must be (weigh crucible before and after evaporation) More detailed protocol and equipment information can be found at the QFAB Metal Evaporator page.
