Login

  1. Fill up the log book.
  2. Make sure that the person who was using the PlasmaTherm before you is done with it.
  3. Turn the placard on the machine with In Use showing.

Vent Chamber

  1. Make sure that the control panel key is in the MANUAL OPERATION position.
  2. Hold the MANUAL button, together with the USE TURBO button (both LED's should be lit together for such operations which requires two buttons to be pressed together).
  3. Now the USE TURBO light will start blinking till the chamber has been vented and atmospheric pressure has been reached.
  4. When the USE TURBO light stops blinking (after ~ 2mins) the chambers may be opened. Both the chambers are vented simultaneously.

Clean Chamber

  1. Wipe the inside of the chamber with texwipes using isopropanol.
  2. Wipe the O-rings with texwipes, to make sure that the chamber is airtight.

Load Samples

  1. Load samples in the chamber that you desire to use.
  2. With chamber selection key (top of figure 2), choose the correct chamber.

Pump down

  1. Close both chambers.
  2. Depress the MANUAL and PUMPDOWN buttons at the same time.
  3. The PUMPDOWN light will start blinking.
  4. Once the chamber has been pumped down the light stops blinking and you are ready to program.

Programmed Operation

Program the Process

Background

The PlasmaTherm has 9 programmable processes. The first four for this unit are reserved and are listed on page 1. You can use programs 5-9 for your processes.
 In general any process consists of the following 7 steps.

      1. Pump Down step: In this step, the chamber is pumped down to get rid of possible contaminant gases.
      2. Purge: The chamber is purged with the reactive gases. This step ensures that only the reactive gases will be present during the reactive step.
      3. Pressure stabilization: The pressure is set and the gases are flowed till the desired pressure is reached.
      4. Reaction: The RF power is turned on. This is the actual deposition / etching step. Here you should be able to see the plasma.
      5. Pumpdown: Now that you are done with the deposition/ etching, the reactive gases with byproducts are pumped out. Note: You should open the chamber only after all the 7 steps are completed, specifically after step 5-7 (especially after you abort the run).
      6. Nitrogen Purge: Chamber is purged with nitrogen to flush out the gases.
      7. Pumpdown: This nitrogen (with some residual gases) is pumped out.

Each of the above steps involves programming the step time, gas flow rates, pressure and the rf power. The values that are programmed in are listed out in the recipe sheets.

Programming

      1. Turn control panel key to CHANGE STORED PARAMETERS.
      2. Choose process no. (Example : To choose process 5, press PROCESS and 5 together.)
      3. Start with step: Press STEP and 1 together.
      4. Set desired parameter from the recipe sheet. (Example: To set pressure for step 1 to 0, press SET and PRES. This will cause all the numbers of the control panel to light up. Now enter 0 and then press STEP(ENTER) again. Now the all the lights of the number pad will go off and the value has been set.
      5. Repeat for all other parameters and then for all the steps.

Running the process

  1. Select the appropriate gases using the switches shown in figure 2 as some of the gas lines are hooked up to more than one gas. If you are using CHF3, the valve needs to be turned on and is located in the service bay behind the PlasmaTherm. After you are done close the valve. Be careful when you go into the service bay. The floor is slippery because of oil from the pump.
  2. If your deposition is to be done above room temperature then START the heater (again a toggle switch). The temperature indicator and control is on the lower left of the PlasmaTherm. Pressing the knob and then turning it sets the temperature. It typically takes 1 hour for the deposition chamber to heat up to 300oC.
  3. Turn the control panel key to MANUAL OPERATION. Select your process, choose step 1 and press RUN. (Example: For running process 6, press PROCESS together with 6, then STEP together with 1 (to make sure that the process starts with step 1), then press RUN.

To stop the run midway

  1. To pause the process, just hit STOP once.
  2. To abort the process and reset to the beginning, hold STOP for around 5 seconds (till beeping stops). Whenever you abort the process and want to open the chamber do a manual nitrogen purge before opening.
  3. Manual Nitrogen Purge:
    1. Press MANUAL and GAS 3 together. GAS 3 light should turn on.
    2. Now press SET and GAS 3 together, now number pad will be lit.
    3. Punch in 30 and then press STEP/ENTER. This will set a 30% (of maximum flow) of N2.
    4. Let the nitrogen flow for 2 minutes.
    5. Press MANUAL and GAS 3 together again. The GAS 3 light should go off.
    6. Now do the vent sequence to open the chamber.

Note: Make sure that the gases are flowing. (Example: To check the flow rate of gas 4. When you are in step 2, press READ and GAS 4). This value is usually a bit different from what was programmed. If this value is very low then press the GAS DEMAND switch (figure 2). If flow rate is still low then abort the process and talk to John about it.

Manual Operation

Parameters like pressure and gas flow rates can be set manually.
  1. For this the control panel key should be in the MANUAL OPERATION mode.
  2. Now if you want to set gas 2 flow rate to 50% then you would first activate gas 2 by pressing MANUAL and GAS 2 together. This causes the GAS 2 LED to light up.
  3. Now the flow rate can be set by pressing SET and GAS 2 together which would cause the data entry pad to light up.
  4. As in the programming section you would enter the value and then press ENTER.
  5. Once you have set the desired gas flow rates and the pressures you can turn on the rf power. With the current rf unit the is turned on by setting the desired power using the dial control and then throwing up the rf on switch.
  6. When the process has run for the desired time (that you are monitoring) first turn off the rf then deactivate pressure control (this can be done by pressing MANUAL and PRESSURE together again) and then deactivate the gas flow controls.

You should in general following the step by step procedure giving in the recipes (i.e. turn on gases, set pressure, turn on rf , switch off rf, turn off pressure control, turn off gases, turn on nitrogen, purge with nitrogen for 3-4 mins, turn off nitrogen.

Vent Chamber

Same as done in the beginning. Take out your samples.

Pump Down and Clean

  1. Do the pump down as described earlier.
  2. The chamber has to be cleaned using a plasma based cleaning recipe. Process 1 has been programmed to do a 60 min clean using CF4. (for the deposition chamber make sure that CF4 is selected using the selector knob).
  3. Now run Process 1. Make sure that gas is flowing (described in Running the Process), logout and now you may leave.

Emergency shutdown

In case of emergency, hit the big red EMO button on the left side of the Plasma-Therm. This will switch off the hazardous gases and the power to the machine.

Trouble-Shooting

Gas is not flowing

    1. Make sure that the valves of the relevant cylinders are open. All the gas cylinders (except oxygen & silane) are behind the plasmatherm in the maintenance bay.
    2. Press the green gas demand button shown in figure 2 in the instructions.

Manual rf unit turned itself off

This happens when the rf unit is overheated. Run your process with lower power setting or do it in multiple runs.

Hold light lit / Machine seems to have hung

    1. If the hold light is lit, this has happened because the process had been paused in the middle of the run.
    2. Press the stop button for 5 seconds till beeping stops.

Note: hitting the stop button once merely pauses the process. To restart the process you have to hold the stop button for around 5 seconds till beeping stops.

Oxide is spotty

This happens when the shower head is dirty. Do a plasma clean + wipe till the shower head looks clean.

Pressure in pumpdown state too high

When this happens press MANUAL + PUMPDOWN again.