Sputter Deposition

From LPDwiki

Necessary Materials and Instruments

1. Piranha cleaned glass slides (or samples on which the film should be deposited)

2. Lesker Sputtering Instrument

3. Metal targets: Gold (Au), Silver (Ag), Chrome (Cr)

4. 6 Silicon wafer on which samples are loaded + Kapton® polyimide tape

Starting Comments

  • Reserve the instrument on Badger, but then email Chan to tell him which targets will be needed at what time and day. He weighs Au before and after sputtering and stores it in a safe place.
  • Leave the targets around Lesker once done and email Chan saying where they were left after being uninstalled.
  • Wore mask when the chamber is open! The temperature should be 11-14 K!
  • np - Au recipe: JV Cr Au Ag 100W, 600 seconds co-sputtering, details explained below.

Initial Check

1. Check that Lesker pressure is ~5e-6 upon arrival.

2. If it all looks ok, start Vent PC.

3. Once pressure is down, Door Lock OFF.

4. Wait for 20 seconds after opening the chamber. Wear mask!

5. Uninstall target compartments. Make sure to open shutters before uninstalling to be able to take the shield off.

Installing Targets

1. Targets are 2, 3, 4, 5 (1 is missing because it is too crowded).

2. Unscrew the 3 screws that hold the outside chamber.

3. Now, unscrew the target (4 screws), only 3 are enough to be unscrewed to take the samples out.

4. Be careful not to get the screws fall in the machine!

5. After installing targets, check the voltage.

5a. Omega Setting on the voltage meter.

5b. Put red pin on the outside shield.

5c. Put black pin on the target itself.

5d. The voltage should be >2 Mega Ohm.

6. Check that all shutters can open/close properly and that they are not loose.

7. Use vacuum cleaner at the end of processing to clean up any particles that might have fallen down.

Preparation of the Chamber and Samples

1. Once the targets are installed, under Vacuum → PC Door Lock ON.

2. Start the PC pump, it takes 40 - 50 minutes (Cryo pump will turn at one point).

3. The pump will stop at 4e-6 and Recipe will be complete → Press OK.

4. Load the piranha cleaned samples on 6’’ wafer (it is the best to load them while the pump is decreasing the pressure).

  • Use two round edge tweezers to load the samples on a wafer surface.
  • Cut small pieces of Kapton® polyimide tape and use two per each sample to secure its edges on the wafer surface.

5. Once the samples are loaded, Open LL and put loaded wafer in. Make sure that the sample is properly sitting.

6. Use vacuum cleaner to clean the holder if necessary and use IPA to further clean it.

7. Close LL chamber and make sure it is tight!

8. Start LL pump.

8a. If it gives the warnings, than: Platen Motion → Reset → Home.

8b. And LRP Motion → Reset → Home (Reference has to show as green for all three motors).

8c. Once the motors are restarted, the LL chamber should start pumping and it will eventually become black , which means it is under a low pressure.

9. Once LL chamber pressure recipe is complete → Start Sample Load.

10. Check Deposition → Sample Status → Should be LOADED.

11. Now the desired Recipe can be run!

Recipe Design

  • Parameters presented in the tables below should be used to design recipes for np-Au and pl-Au in general.
  • Sputtered np - Au samples need to be dealloyed after alloy deposition to get the samples used for testing.
pl - Au, JV Cr Au 100 W
Cr Gun 5 300 W 10 mTorr 180 sec pre-sputtering 300 sec sputtering 100 sec co-sputtering with Au
Au Gun 3 100 W 10 mTorr 20 sec pre-sputtering 100 sec co-sputtering with Cr 300 sec sputtering
np - Au, JV Cr Ag Au 100 W
Cr Gun 5 300 W 10 mTorr 240 sec pre-sputtering 300 sec sputtering 100 sec co-sputtering with Au
Au Gun 3 100 W 10 mTorr 20 sec pre-sputtering 100 sec co-sputtering with Cr 200 sec sputtering 600 sec co-sputtering with Ag
Ag Gun 2 200 W 10 mTorr 20 sec pre-sputtering 600 sec co-sputtering with Au 10 sec sputtering

Note: Below described recipe is for the deposition of planar Gold (pl-Au).

1. For pre-sputtering we use Ar gas, but before inserting it, the pressure needs to be increased from 10-6 to 10-2.

  • The is done by adjusting the throttle valve.
  • The inner circle of the valve has to be in the edge of the outside casing, with the metal part facing up. This is how SCCM is adjusted as well.

2. Protect Ion Gauging by turning it OFF (Ion Gauging should be turned on only at low pressures, 5e-6).

3. Now, PC → High Vacuum Throttle.

4. Now ready to increase the pressure → Gas Window.

5. Gas → Pressure Control → 10 mTorr.

6. Turn ON Gas Injection.

7. One master → Argon → mode 4 → Gas Injection (10 mTorr Capman pressure).

8. If there is something weird with pressure, check if the Ar line is open or not?

  • Note: SCCM → Flow rate cm3/min, max rate is 100 SCCM (Adjust throttle valve to decrease SCCM).

9. Deposition of Cr

9a. Turn on Power Supply for the Source Shutter.

9b. Turn on Power Supply 5 for Chrome.

9c. Ramp Rate → 20

9d. Setpoint → 300W

9e. Turn on Power Supply

9f. Platen Motion → FWD (5 rpm max)

9g. Now Open Substrate Shutters → Click on them to open

10. Deposition of Au

10a. Ramp rate → 20

10b. Setpoint → 100W

10c. Turn on Power Supply

10d. After 100 seconds, Turn OFF Cr

10e. Ramp Rate → 20

10f. Setpoint → 0

10g. Once it reaches 0, Turn OFF

10h. Shut down if it is a Shutter.

10i. Open Au

10j. After sputtering, Shut Down by:

10k. Turn off Substrate Shutter

10l. Turn off Source Shutter

10m. Ramp rate → 20

10n. Power 0 → Turn off

10o. Platen Motion → FWD OFF

10p. Gas → Gas Injection OFF

10q. Make Capman pressure 0, as well as Mode 0.

10r. PC High Vacuum Throttle OFF.

10s. Turn back on Ion Gauging, but make sure the pressure is low enough.

Shutting Down

1. Start sample unload → Sample Unload.

2. Once sample is out, do LL Vent.

3. Get the sample out when done.

4. Start PC Vent, if there are any errors, play with Platen and LPR Motion (Reset, Home, Green Reference Button).

5. PC Door Lock OFF.

6. The gap should open. Keep away from the door for 20 seconds to avoid particles inhalation.

7. Uninstall targets and make sure to email Chan to put them all back to safe.

8. Lock the door.

9. Start PC Pump and wait until Cryo pump turns on.

10. Make sure to log off from Badger and disable Lesker.