Trion RIE/ICP - (Trion Technology Minilock Phantom III RIE/ICP) Contact Information:   Faculty Contact:   Aaron Hawkins   Staff Contact:   Don Dawson   Student Contact:   Evan Lunt Maintenance Request for Trion ICP SCHEDULER IS REQUIRED

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1. General Description
   
   1. The Trion Minilock Phantom III RIE/ICP is used for anisotropic dry etching of silicon oxide, silicon nitride, polysilicon, aluminum, and gallium arsenide. In addition to a Reactive Ion Etching (RIE) RF generator, the Trion uses an Inductively Coupled Plasma (ICP) RF generator to produce a high-density plasma, which allows for lower process pressures, higher etch rates, and higher anisotropy than RIE alone. Trion's electrostatic chuck with helium backflow also increases sample cooling during the etching process. The process gases used with the Trion are O₂, CF₄, CHF₃, SF₆, BCl₃, and Cl₂.
   2. The system is equipped with a load lock and can process one 4 inch wafer at a time. Smaller, flat samples can be etched if they are mounted in the center of a 4 inch carrier wafer.
   3. When a process is running, you should be able to see the plasma through the sight glass
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2. System Overview
   
   1. Trion RIE/ICP Labeled Diagram
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   2. Button Definition
      1. EMO Button:
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         2. This will automatically shut off all power to the system including the computer, RF generators, turbo controller, pump, and gas cabinet. This push-activated button must be twisted to release. The system will NOT turn on until the user presses the "MAIN" button.
      2. Three Button:
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         2. OFF Button: This will turn off power to the computer, RF generators and turbo controller. If the system is OFF, press the "MAIN" button to restart.
         3. MAIN: This will turn off the power to the computer (and close all gas and vacuum valves), the RF generators and the turbo pump. You must press the "EMO" button to shut off the pump.
         4. PUMP: This will turn on the chamber roughing pump.
3. Operating Instructions
   
   1. Start Up Procedure
      1. 1. The process gases are located in the back pump room. Make sure the necessary gases are turned on by opening the valves on top of the cylinders. Make sure you turn on the helium as well (for wafer cooling).
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      2. 2. On the touch screen, press "Load/Edit Recipe".
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      3. 3. On the next screen, you will see all of the process parameters. You can edit any parameter by touching it.
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      4. 4. Press "Recipe From Disk" to load a saved recipe or "Create New Recipe" if you want to start with a blank recipe.
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      5. 5. Choose your recipe from those listed. (Press "next screen" if your recipe is not listed)
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      6. 6. After choosing the recipe, press the "Exit" button. Now, your recipe will be displayed, and you can edit any parameters you like. Press the "Exit" button when finished.
      7. 7. Press "Download Recipe" to download to the controller.
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   2. Loading A Wafer
      1. 1. Press "Load Wafer" on the main screen.
      2. 2. In the pop up window, press "Vent Lock First".
      3. 3. Once the system is vented, the load lock lid will open automatically.
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      4. 4. Put the wafer on the loading arm very carefully.
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      5. 5. Make sure you align the flat of the wafer with the flat of the loading arm. If you do not, your wafer might break inside the chamber!
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   3. Automatic Etching Process - Use when you have a proven recipe.
      1. 1. Press "Automatic Single Process" button. Once the button is pressed, the whole process will run and nothing can be changed until it finishes except for the RF tuning.
      2. 2. When your process is finished, the main screen will be displayed.
   4. Manual Etching Process - Use when you are developing a new recipe.
      1. 1. On the main screen, press "Manual Process Control".
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      2. 2. Load a saved recipe or start a new recipe and change the parameters as needed.
      3. 3. Press "Press Iso Closed" and it should turn green. This opens the isolation valve between the Baratron pressure gauge and the chamber.
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      4. 4. Then press "Gases Off" to turn on the gases and wait for the pressure to stabilize at the process pressure.
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      5. 5. When everything is ready, press "RF Off" to start the RF. Once the RF turns on, the "Process Time Read" counter will start to COUNT UP (Not count down). This timer is only for your information, since the process will not stop automatically.
         1. Looking through the sight glass into the chamber, you should see a stable plasma with no flickering.
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      6. 6. Monitor the reflected RF power for both power supplies. If the automatic tuning does not reduce the reflected power for either supply to below 5% of the set point, use the Tuning Procedure shown below to manual tune the RF.
      7. 7. Once you have etched for the desired time, press "RF On" and "Gases On" to turn off the RF and the gases (the buttons should turn gray).
      8. 8. Press "Exit" to return to the main screen.
   5. Unloading A Wafer
      1. 1. Press "Unload Wafer" and remove your wafer from the load lock when it finishes venting.
      2. 2. Press "OK" to pump down the load lock when you are finished.
   6. Shutdown Procedure - Do this if the machine will not be used for over an hour.
      1. 1. On the main screen, press "Stand By Mode" to place the system in standby. This involves purging all gas lines and mass flow controllers and pumping down the chamber and load lock.
      2. 2. Turn off the gases in the back pump room.
      3. 3. Sign the user log.
4. Tuning Procedure
   
   1. 1. Open the flip door on the system console.
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   2. 2. There are two sets of switches - the top set is for the ICP matching network, the bottom is for the RIE matching network.
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   3. 3. Both networks should normally be in the "Auto" mode (up). Flip the "AUTO/MANUAL" switch to the fully down position for manual tuning. The selection switches have 3 positions: up = automatic, middle = nothing, down = manual.
   4. 4. While watching the measured reflected power on the process screen, adjust both the "C1" and "C2" switches iteratively for each power supply to minimize the reflected power. These switches are momentary, so when you release them, they will return to the neutral position. If you cannot get the reflected power below 15 W or 5% of the forward power within 60 seconds, shut off the RF power!
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   5. 5. After minimizing the reflected power, leave the "AUTO/MANUAL"switch in the manual (down) position. Switching it back to the automatic position may increase the reflected power. After your process has run to completion, make sure you leave the switches in the "AUTO" position.
5. Cleaning Procedure
   
   1. The chamber should be cleaned after every etch over 5 minutes long.
   2. 1. Load a bare silicon wafer into the chamber. This must be done to avoid damage to the wafer lift pins in the chamber.
   3. 2. Load the "CLEAN" recipe from the disk and run the program in manual mode. You will have to tune both the RIE and ICP manually. Run step 1 for 5 minutes, then run step 2 for 5 minutes.
   4. 3. Unload the silicon wafer when you are finished.
6. Troubleshooting
   
   1. When running a multi-step process, do not use more than 13 steps. If you do, the first step will not work properly.
   2. Make sure you align the flat of the wafer with the flat of the loading arm, or your wafer might break during the load/unload proceedure.
   3. Use tape on the backside of the wafer to insure that the wafer doesn't fall during the load/unload proceedure. If you don't know how to do this, contact Evan Lunt.
   4. If there are any questions regarding the Trion RIE/ICP Etcher, please contact Yue Zhao for more information.
7. Common Recipes
   
   1. Use Helium backflow of 5-10 Torr on all recipes. Higher flow should improve wafer cooling and selectivity. Etch rates and selectivities will be slightly different when etching a small sample on a carrier wafer or a full wafer.
   2. Recipe Adjustment Characteristics
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   3. Silicon etch process - good uniformity
      1. 1. Deposition step
         1. RIE Power: 0 Watts
         2. ICP Power: 600 watts
         3. Pressure: 120 mTorr
         4. Gases: CHF₃-75sccm
         5. Step Time: 32 seconds
      2. 2. Etch step
         1. RIE Power: 75 watts
         2. ICP Power: 600 watts
         3. Pressure: 35 mTorr
         4. Gases: CHF₃-30sccm, SF₆-10sccm, 0₂-2sccm
         5. Step Time: 30 seconds
      3. Etch Rate: 530A/min (etching time)
      4. Uniformity: ~3% variation
      5. Selectivity: ~3
   4. Silicon etch process - good selectivity to PR or SU-8
      1. 1. Deposition step
         1. RIE Power: 0 Watts
         2. ICP Power: 600 watts
         3. Pressure: 120 mTorr
         4. Gases: CHF₃-75sccm
         5. Step Time: 32 seconds
      2. 2. Etch step
         1. RIE Power: 75 watts
         2. ICP Power: 600 watts
         3. Pressure: 120 mTorr
         4. Gases: CHF₃-30sccm, SF₆-10sccm, 0₂-2sccm
         5. Step Time: 47 seconds
      3. Etch Rate: 330A/min (etching time)
      4. Uniformity: ~10% variation
      5. Selectivity: >10
   5. Silicon Dioxide (Si02) - Anisotropic, poor selectivity to PR or SU-8
      1. RIE Power: 75 watts
      2. ICP Power: 600 watts
      3. Pressure: 12 mTorr
      4. Gases: CF₄-50sccm
      5. Etch Rate: 3600A/min
      6. Uniformity: ~3% variation
      7. Selectivity: ~1.3
   6. Silicon Dioxide (Si02) - Anisotropic, poor selectivity to PR or SU-8
      1. RIE Power: 55 watts
      2. ICP Power: 350 watts
      3. Pressure: 20 mTorr
      4. Gases: CHF₃-125sccm, 0₂-5sccm
      5. Etch Rate: 1250A/min
      6. Uniformity: ~3% variation
      7. Selectivity: ~1.5
   7. Silicon Nitride (Si₃N₄)
      1. RIE Power: 100 watts
      2. ICP Power: 0 watts
      3. Pressure: 250 mTorr
      4. Gases: SF₆-45sccm, 0₂-5sccm
      5. Etch Rate: 2500A/min
   8. Polysilicon
      1. RIE Power: 100 watts
      2. ICP Power: 0 watts
      3. Pressure: 300 mTorr
      4. Gases: SF₆-50sccm
      5. Etch Rate: 5000A/min
   9. Polyimide or Photoresist
      1. RIE Power: 100 watts
      2. ICP Power: 250 watts
      3. Pressure: 150 mTorr
      4. Gases: 0₂-45 sccm, SF₆-5sccm
      5. Etch Rate: 10000A/min
      6. (Note: If you do not want to etch into the passivation layer, the SF6 gas can be eliminated. In eliminating the SF6, the pressure needs to be lowered to 30 mtorr to ensure a clean etch.)
   10. Aluminum
       1. RIE Power: 75 watts
       2. ICP Power: 0 watts
       3. Pressure: 180 Mtorr
       4. Gases: BCl₃-30 sccm, Cl₂-30 sccm, CF₄-2sccm
       5. Etch Rate: 1000A/min
       6. (Note: The CF₄ is not necessary but ensures a smooth sidewall passivation on the aluminum. To increase the etch rate, increase the Cl₂ flow. Be sure to rinse the wafer after processing because the residual chlorine will combine with moisture in the atmosphere to form small amounts of HCl.)