Loading samples

Step by step guide to loading samples.

At the start of this procedure it is assumed that the loading substrate holder is attached to the main arm and in the pretreatment chamber and all systems are running per usual. It is adviced to have an area in the fumehood already cleaned and tweezers etc ready beforehand.


1. Open the gate between the load lock and pretreatment chamber.

2. Lower the sample holder stack all the way down until it attaches to the lower holder with the magnetic base. NOTE: The base should be as far back (away from the door) as possible when you lower the stack down on it.

3. Move magnet towards the door (this removes the lower part of the stack allowing its extraction).

4. Move the stack all the way up again.

5. Close the gate between the pretreatment and loadlock chambers.

6. Close the gate between the loadlock chamber and the turbomolecular pump.

7. Stop the turbomolecular pump.

8. Gently open up the argon flow to the loadlock chamber - do not open too much at once! If there is no gas coming in check that the line is open first next to the fumehood (it is the line furthest to the left) or by the bottles outside. It is also good to unscrew the door now, as it will be easily visible then when the loadlock has reached ambient pressure.

9. When the door opens, gently remove the holder stack and move it to the fumehood.

10. Take the substrate holder with the new wafer (see below on how to attach it) and place it in the rack. The rack can transfer a maximum of 3 wafers at the time.

11. Once the desired number of wafers are placed in the rack, move it back to the loadlock and place it inside. NOTE: there is a back and front on the rack, make sure you get it the right way around. Also, make sure it sits nicely in the loadlock chamber.

12. Close the loadlock.

13. IMPORTANT: In order to pump it down again we need to make sure that the turbomolecular pump has completely stopped. Opening the gate between the loadlock and the pump before it completely stops could destroy it. You can determine its status by looking at the lights on its bottom:

GREEN and YELLOW constant - running normally.

GREEN blinking and YELLOW constant - slowing down.

YELLOW constant - stopped and in stand by.

Once the turbomolecular pump has completely stopped you can open the gate between the pump and the loadlock and start the pump again.

14. As the loadlock is pumping down you can start the script LLDegas in Molly. Make sure to put aluminium foil over the glass. This programme should take ~2h to run.

15. When the loadlock is degased you open the gate between it and the pretreatment chamber.

16. Lower the stack holder arm all the way down.

17. Once the arm is all the way down you can slide the magnet away from the door - raising the stack holder arm now should automatically attach it to the arm.

18. Raise the arm back into the pretreatment chamber.

19. Close the gate between the loadlock and pretreatment chamber.

20. Run the degas script relevant to your wafer (Eg. Si Degas for Si...) This script may be as long as 3 hours (Si). Remember to cover the window with aluminium foil.

21. Once this process is finished it should be all right to transfer the wafers to the growth chamber or "store" them in the pretreatment part.

Extra - substrate holders

1. The substrate holders are kept in the cabinet on the opposite side of the room from the fumehood. Get an appropriate holder for your sample size and geometry. Remember to bring a ring if it is not already there.

2. Using tweezers place your substrate in the holder with the side you wish to deposit on facing down.

3. Using the pointy tweezers take the ring and place it appropriately above the substrate.

4. Pinch the ring using the two holes, this allows it to slide down into the grove. Use a second set of tweezers to make sure it is in contact with the substrate all around.

5. Release the ring.