Purpose:  To deposit a directional layer of metal or dielectric to the surface of a sample

Location: Marcus Inorganic Cleanroom

Tools: Denton Explorer, PVD 75 Filament Evaporator, CVC E-beam Evaporator, CHA Metal and Dielectric Evaporators

Supplies Needed: crucible, material to deposit, sample holder, kapton tape (if necessary), vacuum, isopropanol, texwipe, and tweezers

Setup Procedure

1. Schedule time well in advance
2. Check that the back side of the wafer is clean, and the front side is free of any unwanted debris
   • If the evaporation is being used for liftoff, be sure to run your sample through a descum before. (see cleaning section)
3. After venting the chamber, clean the inside of the chamber
   • Vacuum the chamber carefully
     • Do not vacuum the crucible
     • Do not knock anything down into the vacuum lines or valves
   • Wipe down the chamber with isopropanol and a texwipe
     • Remove carbon deposits that may have formed
   • Make sure the O-ring is in place and clean it with isopropanol and a texwipe
4. Check the crystal of the deposition monitor
   • Change the crystal when the life is above 10
5. Check the crucibles being used in your process
   • Make sure that the crucibles have enough material inside of them for the intended deposition
   • Make sure that the crucibles have the material you intend to deposit and that it is melted
   • Make sure that the crucibles are not cracked or damaged
   • Check for contamination of the material
   • Wipe off the top of the crucible material with a texwipe and a very little amount of isopropanol
   • Finally make sure the crucible is sitting correctly in the holder
   • If required, make sure that the spacer is there as well

Number of Substrates: < 1 – 3 (4” wafer size)

Process Procedures

1. Mount your sample
   • Make sure that the sample is mounted securely to the chuck with kapton tape (if necessary)
2. Turn on the rotostrate, if applicable
3. Allow enough time for the tool to pump down to the necessary pressure
   • Typically, the pressure is at LESS THAN 2x10^-6 Torr
   • Lower pressures required for easily oxidizing materials (i.e. chrome should get to the 10^-7 scale)
   • Most tools will take 30-90 minutes to reach this pressure
4. Check the recipe parameters
   • Parameters that can be changed: deposition rate, final thickness, crucible number, material deposited
   • Parameters that should not be changed: power, pressure, spin speed
5. Turn on the power supply
6. Start the recipe
7. Make sure the electron beam is hitting the middle of the crucible
   • If the beam is not in the middle of the crucible, adjust it
   • if you cannot adjust the beam to the middle of the crucible, stop the process and ask the staff for help
8. Watch to make sure that the material in the crucible does not run out during the process
   • Monitor the deposition rate during the run. If the rate begins to change noticeably, there could be an issue with the crystal monitor
9. Vent and clean the chamber if needed
   • Allow at least 10 minutes to pass prior to venting. This allows the material to cool and prevents oxidation of the source material.
   • Clean if you see flaking on the walls or particles in the chamber
10. Un-mount the sample
11. Pump down the chamber and sign out of the tool
12. Cancel any unused time that was scheduled

Verification:

• Sheet Resistance: can be measured with the Signatone Four-Point Probe
• Film Thickness: can be measured accurately with Nanospec Refractometer or the Woollam M2000 Ellipsometer
• Film characteristics: can be measured with the Woollam M2000 Ellipsometer
• Step Height: can be measured with the Dektak 150 Profilometer, Tencor P15 Profilometer, or the Wyko Profilometer NT3300