The oxides sputtering system is a epitaxial-growth high-pressure non-magnetron sputtering system with specially adapted sources that operate at pressures up to 5 mbar! The background pressure is typically <1e-6 mbar after a night of pumping and 1e-7 mbar is the minimum. The system is equipped with a 1200 C substrate heater that can rotate over the sources. Oxides are sputtered reactively, a 3-gas blending system for Ar, 0₂ and N₂ is mounted as well as special gas inlets for annealing. The power supplies are 2 slow-ramping DC supplies and a self-matching RF supply.

Safety issues for yourself and for the system:

• Before sputtering, make sure that all power supply cables are connected
• When pumping down, switch off cooling water for the sources and x-tal
• When starting, make sure the interlocks are wired correctly. Do not plug 2 power supplies in the connector for the same cooling water loop!
• After that, check whether the flow meters work and switch on cooling water for the sources and x-tal

The most complex process is YBCO growth. That process is described here.

1. Check whether all gas inlet valves are closed
2. Close the gate valve
3. Switch off the pumps with the central pump switch
4. Switch off the cooling water

1. Vent the chamber by opening the N₂ chamber valve and turning the gas selector valve to N₂
2. Close both valves when the pressure is 8e2 Torr.
3. Switch on the Lift main switch
4. Raise the top of the system using the lift control unit and rotate the top to the left.

1. ALWAYS wear gloves when touching substrates and system parts
2. Remove the heater shield
3. Remove samples, clean sideplates in HNO₃
4. Clean the heater surface 1)with a razor, 2)with 400 grit sandpaper, 3) with 800 grit sandpaper, 4) with Scotchbrite. Clean with IPA. This step is crucial!
5. Mount the sample with SPI silver paste plus II (should be kept in freezer, warm up before use) and squeeze the substrate against the heater with the glass tool (clean before use)
6. Shine a halogene lamp on the substrate for 15 minutes
7. Cut away glue around the substrate
8. Mount side plates, push them flush against the substrate using a cotton tip.
9. Set the heater to 80 C for 1 hour using the Eurotherm control software
10. Dry for >1 hour
11. Mount the heater shield, blow possible dust particles away with N₂

1. Rotate the top above the chamber and lock it in place
2. Lower the top very carefully making sure that the teflon guides slide along the chamber (take into account safety rules for working with heavy objects)
3. Switch off the lift main switch

1. Open the gate valve
2. Switch on diaphragm pump
3. Wait until the pressure is about 5 torr on the pirani or 8 mbar on the capacitance gauge
4. Switch on cooling water
5. Switch on turbo
6. At 800 Hz: open main gas valve under the chamber
7. Check that the ion gauge switches on
8. Pump overnight

1. Pressure should be 1e-6 mbar
2. Position heater between 2 sources, opposite to YBCO
3. Open N₂ purge on the pump. Do not forget this!
4. Open the O₂ valve at the front of the system. Do not touch the O₂ needle valve! Flow should be around 40.
5. Open the YBCO shutter, keep other shutters closed (unless you make a multilayer of course)
6. Switch on the YBCO power supply, current regulation
7. Set the setpoint at 8 ma, display actual current and voltage
8. Switch turbo to pressure control, setpoint 3.5
9. Short after that, when the pressure is between 5e-2 and 1e-1 torr, switch power supply to on. The plasma should ignite. Get help if it doesn't!
10. Let the pressure increase until the voltage gets below 350-380 V (the lower the better!)
11. The voltage keeps decreasing, keep it constant at 350-380 V by increasing current (it is critical that you follow this rate given by the O₂ backfill rate of the chamber and not faster!
12. The turbo pump is at 0 Hz now and starts to accelerate
13. At 100 Hz, set pressure setpoint to previous value from the logbook
14. Keep increasing current, set current to 350 mA (never get above 390 V!)
15. Use the Keithley to read O₂ pressure, fine adjust setpoint so that pressure is between 2.99 and 3.01 mbar (better: 2.995 - 3.005)
16. Let everything stabilize

1. You will see that the conditioning of the target takes quite a while, check that while conditioning the voltage goes down to about the previous value in the logbook.
2. Presputter for >1 hour
3. Program the heater in the meanwhile. There is a recipe for YBCO.

1. Run the recipe
2. When the deposition substrate temperature is reached, the temperature will overshoot 2 or 3 degrees. Get ready to rotate the substrate above the YBCO source.
3. Immediately (absolutely do not wait) when the temperature is right (0-1 degree from the setpoint) rotate the target above the source. Check the symmetry of the plasma and the substrate position. Start a timer.
4. Time the epitaxial growth process

1. Turn the substrate away and press Skip segment on the Eurotherm control program
2. Turn off the power supply and turn the setpoint back
3. Set the chamber backfill selector to O₂
4. Wait until the substrate reaches the annealing temperature + 10 degrees
5. Quickly close the gate valve and the O₂ valve
6. Close the gas valve under the chamber and exactly at the annealing temperature open the chamber backfill valve (you have to be quick here!)
7. Close the chamber backfill valve at 8e2 torr (reproduce this value!)
8. Set the chamber backfill gas selector to neutral

1. Let pump run for 20 minutes
2. Close N₂ purge on the pump.
3. The Eurotherm control program takes the sample trough the annealing temperature profile
4. Wait until the sample temperature is <50 C
5. Check whether all gas valves are closed