Niobium Sputtering Chamber a

Niobium Sputtering Chamber (a.k.a. trilayer system) Operating Instructions
Sergey Frolov and Trevis Crane (June 2004)
LOADING THE SAMPLE

1. 
   Close the gate valve (the valve between the cryopump and the chamber)
   

2. 
   Turn the roughing pump ON
   

3. 
   Bring the chamber up to 150 mTorr with Ar
   Turn on Channel 1 (which is Ar) on the flow controller.
   Open the pneumatic valve on the Ar line. To open, flip the valve switch (left one on the gray panel) up and then back to the middle position.
   When the pressure reaches 100 mTorr, flip the valve switch down (which vents the valve), and back up. The pressure will stabilize at around 150 mTorr. If the pressure is significantly higher than that, adjust it with the roughing pump.
   

4. 
   Vent the loadlock with N2, attach the sample chuck to the loading rod, pump the loadlock with the roughing pump below the pressure of the chamber.
   

5. 
   Orient the sample holder to the correct loading position according to the diagrams drawn on the bench. Be sure to only turn the sample holder clockwise.
   

6. 
   Close the roughing pump valve, open the loadlock valve, bring the sample down into the sample holder. Pull the loading rod out of the main chamber, close the loadlock valve.
   

7. 
   Pump the chamber down.
   First, pump with the roughing pump down to 100 mTorr. Main chamber roughing pump valve is controlled by a black knob next to the gate valve (IF YOU HAVE ANY QUESTION AS TO WHICH BLACK KNOB THIS IS, DO NOT TURN EITHER – ASK TREVIS). Do not pump lower than 100 mTorr to avoid the chance of oil back-streaming into chamber. When the chamber reaches 100 mTorr, close the roughing pump, fully open the gate valve.
   

ION MILLING

1. 
   Initiate Ar gas flow
   

Do not use the flow controller or pneumatic valves. Use the green bypass valve next to the Ar flow meter. With the gate valve fully open, that should give desired pressure of Ar (2-3x10^-4)

2. 
   Turn the ion mill POWER switch ON. The ion mill controls should be set to the correct values. After that, turn the SOURCE switch ON, the Discharge light will initially be blinking. When the Discharge light stops blinking, turn the BEAM switch ON. The beam current should read around 20-30 mA. Adjust the neutralizer current to be slightly higher than the beam current.
   

3. 
   Ion mill for 25 seconds for cleaning purposes. When done, turn the BEAM OFF, turn the SOURCE OFF, turn the POWER OFF.
   

SPUTTERING NIOBIUM

1. 
   Initiate Ar gas flow.
   Make sure that the setpoint for the Ar flow is 90 sccm. Ar is Channel 1 on the flow controller. Open channel 1 and actuate the pneumatic valve. Adjust the gate valve so that the chamber pressure is 10 mTorr.
   

2. 
   Turn ON the water
   

3. 
   Flip RF/DC switch into the DC position
   

4. 
   Start the plasma
   Turn on the DC supply. On the DC supply select 3 for Nb gun. Turn HIGH VOLTAGE ON. Start cranking up the voltage till you see plasma (~300 V). If the gun doesn’t light, try closing the gate valve. If that doesn’t work, turn on the ion-mill. Make sure to bring the pressure to 10 mTorr with the gate valve after the plasma is lit.
   

5. 
   Sputter at 15 A/s.
   Watch the sputtering rate at the crystal monitor. Adjust the voltage so that the rate is roughly 15 A/s. Presputter (with the shutter closed) for 3 minutes, though you can adjust your voltage to get the correct rate during the pre-sputter period.
   
   
   

6. 
   When done, turn the voltage down gradually. Turn the HIGH VOLTAGE OFF then turn the DC POWER SUPPLY OFF.
   

SPUTTERING SIO2

1. 
   Initiate gas flow (Ar and O2)
   Setpoint for Ar is 90 sccm, O2 should be 0.1 of that, so 9 sccm. O2 is channel 2 on the flow meter. To start the flow of O2, flip the O2 pneumatic control valve switch up and back into the middle position. The switch is located at the right side of the gray panel. With both the Ar and O2 flowing, keep gate valve open fully.
   

2. 
   Turn ON the water
   

3. 
   Switch RF/DC switch into RF position
   

4. 
   Turn the POWER ON on both of the US GUN boxes
   

5. 
   Turn RF ON. It should be already preset to put out 350 Watts
   If the plasma doesn’t light, try closing the gate valve. If that doesn’t work, turn on the ion-mill. Make sure to fully open gate valve after plasma is lit.
   

6. 
   The SIO2 gun is the one in the back
   

7. 
   Due to heating of the gun and of the sample, sputter only in intervals of 45 seconds, then keep the shutter closed for 45 seconds, then repeat this process until you achieve your desired thickness
   

8. 
   Turn the RF OFF when you are done (as well as the power to the two US Gun boxes)
   

UNLOADING THE SAMPLE

1. 
   Close the gate valve
   

2. 
   Get the chamber to around 150mTorr by letting the Ar flow into the chamber while you’re closing the gate valve. Once the pressure is at 150 mTorr, turn off the pneumatic valve and the flow controller.
   

3. 
   Evacuate the loadlock with roughing pump
   

4. 
   Take the sample out of the main chamber, close the loadlock valve, take the sample out of the system
   

5. 
   Pump the main chamber down to 100 mTorr (with roughing pump)
   

6. 
   Open the gate valve (be sure the valve connecting the roughing pump to the chamber is closed before you open gate valve) and pump out the loadlock with roughing pump while opening gate valve
   

7. 
   Turn off roughing pump and water