EquipmentOxford Estrelas ICPRIE (DRIE)
Process Area

Plasma Etch


Venting the Estrelas should be done only on an as needed basis, and done by users trained to do so.

There is a high risk of damaging the tool (clamp or table) while performing this task. 

Step-by-step guide

Chamber Venting:

  1. Confirm that venting the chamber is actually required.
  2. Open the Estrelas Chamber Vent and Retrieval Form in order to document pre and post chamber conditions.  
  3. Note the base pressure and turbo current in the form.
  4. Set the table temperature to 20C to avoid condensation forming on the chuck.  To do this, enter the Process Chamber window, and manually enter 20 in the table T cell.  Ensure all power and gases are set to 0.  Press the Start button, wait several seconds, then press the Stop button.  The table will continue to warm despite the process being stopped.
  5. In the Pumping window, press the Stop button, followed by the Vent button.  Do this for both the process chamber and the loadlock.  The turbopump will slowly brake, and will need ~15min to reach 0rpm.  The chamber will automatically vent once the turbo is stopped.  Wait 2-3 more minutes for the chamber to reach atmosphere.
  6. Turn the large brass key at the back of the tool ~45 degrees to the On position enable service mode.  This must be done before the chamber is opened to keep the clamps raised.

Chamber Open:

  1. Undo the two clasps on either side of the chamber.  Ensure the table behind the chamber is cleared (remove the keyboard and mouse from the table).  Be aware that the chamber walls and clamping ring will be very hot while the chamber is open, avoid touching.
  2. Once the chamber is at atmosphere, carefully open the chamber until the lid is fully opened and at ~90 degrees to main chamber.  Take pictures of the wafer prior to cleaning.
  3. Carefully remove any broken pieces by hand (clean gloves only), tweezers, or double sided tape.  Use extreme caution using metal tweezers as the aluminum table scratches easily.  A clean room wipe with IPA can be used to clean up smaller particles.  Avoid touching the clamp as it is fragile, rough (picks up fibers from wipes easily), and expensive.  
  4. Full wafers that drifted off centre or have become stuck to the clamp have to be removed using the loading arm as they won't fit through the clamping ring.  To do this, start by centring the wafer on the lift pin by hand.  In the software, ensure the wafer indicator shows there is a wafer in the process chamber.  Click the wafer and guide it to the loadlock.  The loadlock lid needs to be open to complete the transfer, and the wafer will automatically unload using the loading arm.
  5. Once all pieces or wafers have been removed, do a final wipe of the sealing surface and the chamber lid oring with IPA and a cleanroom wipe.  Carefully close the chamber lid, do not let it slam shut.

Chamber Pumpdown:

  1. If prompted to record chamber pumpdown time, click Yes.  Press Stop and Evacuate for both the Process Chamber and Loadlock.  Allow the turbo to reach speed before continuing.
  2. Once the turbo has reached speed and the process chamber has reached base pressure, record the turbo current.
  3. Perform an empty chamber clean using the recipe Chamber pre-heat clean.  The tool will have to be set to Manual - No Wafer mode in the Recipes tab to do so.  A 15 minute clean is sufficient.  Record the valve position used during the cleaning process.
  4. Record the base pressure once the clean is done.
  5. Perform a chamber leak check by clicking Leak Detection while in the Process Chamber window.  Ensure all gases are set to 0, and the leak check time set to 5 minutes.  Press start, and record the calculated leak up rate.  If >5mTorr/min, there is a leak and the chamber will need to be vented and the sealing surfaces cleaned once again.   Once done, press Stop on the leak up window, and press the Leak Detection button to return to the main screen.  Set the tool to Automatic back in the Recipes tab.
  6. Vent the loadlock again, and load a wafer.  Perform a short clean with a wafer (1min) using the recipe Chamber Clean with wafer.  Record the He flow required to reach the set pressure of 10 Torr.  If >40sccm, there is a poor wafer clamp and/or seal, and will have to be resolved before continuing.  Testing using a second wafer will confirm whether the wafer or the clamp/table is the issue.  If unresolved, the chamber will have to be vented again for inspection and cleaning.

If the above procedure fails to reach required base pressure, leak up rates, or He flows, the tool must be marked down and staff will be required to asses further.  Mark the tool down and fill out a maintenance request form in LMACs.