Microelectronics Research Center

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Plasma-Therm RIE #2

RIEs (reactive ion etchers) are used to etch various materials, such as silicon dioxide, silicon nitride, various polymers, and various metals from the surface of a substrate using various reactive gases in a RF (radio frequency) induced plasma.

The SLR RIE is reserved for III - V materials such as galium arsinide (GaAs). To prevent process contamination no polymers, including photoresist masks, are allowed in this machine.

This RIE is equipped with boron trichloride (BCl3), silicon tetrachloride (SiCl4), sulfur hexafluoride (SF6), trifluoromethane (CHF3), hydrogen (H2), methane (CH4), chlorine (Cl), and a line that can be switched between oxygen (O2) and argon (Ar).

Processes on non - III - V substrates, as well as any process involving polymers, including photoresist masks, must be performed in RIE 1, the "Old" RIE.

Operating Instructions

I. Loading

Operator Login
  1. Login to the machine.
  2. Press the ON button at the bottom of the screen.
  3. Press the STANDBY button at the bottom of the screen.
  4. Highlight Utilities, Loadlock, Vent.
  5. A message will appear at the bottom of the screen when the loadlock finishes venting.
  6. Load sample into the center of the chamber.

II. Operating

Caution: If you are using oxygen or argon make sure that the system is configured for your gas. A sign below the screen should indicate which gas the system is configured for. You can also check the valve on the oxygen / argon line on the wall behind the RIE. 
  1. If you do not already have a recipe and a batch, see the Recipes and Batches sections of this document. Highlight Process, Batch. The batch window will appear. Select File, Load. Select the batch you want to load.
  2. Press the READY button at the bottom of the screen.
  3. After READY parameters have been applied, hold the loadlock cover down and press the RUN button at the bottom of the screen.  Note: If you don't care about the chamber temperature, you can skip the first step of the recipe by pressing END STEP.
Note: Do not press abort without reading these instructions.

If you must abort your process, you may press abort while the process is running. The system will ask "Abort process?" Make sure that these are the exact words used in the message before answering. You may answer yes to "Abort process." You will then be asked "Abort batch?" Never answer yes to "Abort batch?" If you do, your sample will be trapped inside the process chamber and will have to be removed by MiRC staff.

III. Unloading

  1. After the process is over, press the STANDBY button at the bottom of the screen.
  2. If your batch does not automatically vent, highlight Utilities, Vent.
  3. Unload sample from the chamber.
  4. Highlight Utilities, Loadlock, Pump Loadlock.
  5. Highlight Utilities, Logout.

Configuring Oxygen / Argon Line

Oxygen and argon enter the RIE through the same gas line. The RIE can be configured to use either oxygen or argon. If the RIE is not configured for the gas that you want to use, you will need to reconfigure it.

  1. Turn the oxygen / argon selection valve (on the wall behind the RIE) to the center position (off).
  2. Press the STANDBY button at the bottom of the screen.
  3. Select Service, Maintenance, Evacuate Gas Lines. Select the oxygen / argon line.
  4. Wait until the indicated flow rate reaches zero, then wait an additional minute.
  5. Press Exit.
  6. Select Service, Maintenance, Flush Gas Lines.
  7. Check to be sure that the oxygen / argon valve is off. Select oxygen / argon, set the number to 10, then press Start. The mass flow controller will be flushed with nitrogen, then evacuated ten times. When the flush is complete, press Exit.
  8. Press the ON button at the bottom of the screen and wait for the system to enter ON mode.
  9. Press the STANDBY button at the bottom of the screen.
  10. Turn the oxygen / argon selection valve so that the valve handle points to the gas that you want to use.
  11. Select Service, Maintenance, Flowmeter Calibration.
  12. Set the pump to "TURBO". Set the gas channel to "O2 or Ar". Set the gas setpoint to 30%.
  13. Press Calibrate. Calibration will take about two minutes.
  14. When the calibration is complete you will be asked if you want to save the new calibration. Select Save.
  15. Change the sign below the monitor to indicate the gas that is currently selected.

Recipes

Overview

In general, your recipe should have four steps: an initial step, two process steps, and an end step. The initial step evacuates the chamber, removing the air inside, and brings the chamber to the process temperature. The first process step performs your process without RF power for about 30 seconds. This fills the chamber with the process gasses and removes any remaining air from the chamber before the actual process starts. It also allows the chamber pressure and gas flows time to stabilize. Because the RF power is off, no processing will actually take place during this step. The second process step performs the process.

Instructions

From the Process menu, choose Chamber, Build to create a new recipe or Edit to edit an existing one. A list of the recipe steps will be displayed on the right side of the screen. To edit a step, double click on it. To create a new step, select the step that will go after the new step and click the appropriate button for the type of step you want at the bottom of the screen.

Initial Step

Initial Step

All recipes start with an initial step. This step will evacuate the chamber and bring the chamber to the desired operating temperature.

Set the pressure to 5.0 x 10-2 Torr and set the time to 30 seconds. This will cause the system to evacuate as much air from the chamber as possible before starting the process. Do not attempt to use pressure setpoints below 5.0 x 10-2 torr. The chamber will be evacuated as much as possible regardless of the setpoint.

Set the temperature to your desired process temperature. Note that the temperature is measured in degrees Celsius.

You may describe your recipe in the Description box. The first few words will be displayed by the filename when you are loading your recipe.

Process Step

You will usually want two process steps. They should be identical with a few exceptions. The process step dialog box has five major areas: time, temperature, pressure, gas flow, and power.


Process Step
Time

The first process step should be set to "Fixed Time" This step will be used to stabilize the chamber conditions. The time for this step is not critical, but 30 seconds is good.

The second step will actually perform your process. You must set this step to "Fixed Time" and set the time here. Variable time does not work on this system.

Temperature

Set the temperature to your desired process temperature for both process steps. Note that this should probably be the same as the temperature set in the initial step.

Pressure

Set the pressure to the process pressure you want for both process steps. If you are operating the RIE at lower pressures you will need to set the pump to the turbo pump. Otherwise use the mechanical pump.

Gas Flow

Set the flow rate for each gas here. The flow rates are given in sccm (standard cm3/min). The flow rates should be the same for both process steps.

Power

Leave the power set to zero in the first step. Set it to the power you want for your process in the second process step.

End Step

End Step

All recipes have an end step that evacuates the chamber. Set the pressure to 5.0 x 10-2 torr and set the time to ten seconds. When you modify a process, you only change the copy on the disk. If the process is already loaded, you will need to reload it for your changes to be reflected.

Batches

I. Instructions

To create or edit batch, select Process -> Batch -> New or Edit. To add a step, click on the button for the type of step you want to add. To delete a step, select it and click Delete. You will need to add a load step, an unload step, and an end step.

Batch Editor

Pump Loadlock

This will be the first step in the batch. It is automatically included.

Load Chamber

To add a load chamber step, click on the button with the arrow pointing to R or L depending on which chamber you want to load. R stands for right. L is left. A process step will be added after the load step automatically. You will be prompted for a recipe to run.

Process

A process step runs a recipe you have already written. One will be added when you add the load chamber step, but you can add another by pressing the appropriate process button for the chamber you are using.

Unload

The unload step moves the sample back into the loadlock. Press the button with the arrow pointing to the lock to add an unload step.

Vent / End

There are two types of end steps: vent and end. A vent step will vent the loadlock automatically and an end step will not. The last step in a batch must be a end or vent step.

Using Manual Mode

manual mode display Manual Mode

Manual mode allows one to directly control the system parameters without creating a recipe. This can be useful for developing new processes. To operate the system in manual mode press STANDBY at the bottom of the screen. Make sure that the chamber is currently being pumped. Then select Service, Manual Mode. The manual mode window will appear.

This window is divided into four sections: Temperature, Pressure, Gas, and RF Control. Each of these sections is summarized below.

Temperature

This sets the temperature of the bottom and top sections of the chamber. Note that it will take a while for the temperatures to change after you change the settings.

Gas

This sets the flow rates for each of the gases. The gas flow will not start until you press the Gas button at the top of the display.

Pressure

This sets the chamber pressure. The chamber pressure will not be regulated until you press the Pressure button at the top of the display. You must have at least one gas on before you can turn the pressure on.

RF Control

This controls the power. Config should be set to "RIE" and Mode should be set to "Power." Set sets the power in watts. If Time is set to zero, the power will run indefinitely once it is turned on. If Time is set to anything else, the system will run for the time set and then shut off the power, gas, and pressure. Run indicates how long the power has been on. The power will not come on until you press the RF button at the top of the display.

Troubleshooting

The menu option I want to select is grayed out.

Some menu options are not available depending on which mode the system is in. Try switching between the "ON," "STANDBY," AND "READY" modes with the buttons at the bottom of the screen.

The alarm is going off.

To silence the alarm, press the ALARM SILENCE button at the lower right corner of the screen. At the bottom center of the screen, there is a box labeled "Alarm" that will tell you why the alarm is going off.

The reflected power is high or I get an "RF1 detected off" alarm.

If you know that the pressure you are using has worked before, try pressing HOLD one time only to make the system try again. If it still doesn't work, contact an MiRC staff member. DO NOT PRESS HOLD MORE THAT ONCE If you keep pressing hold, you may cause serious and expensive damage to the power supply.

If the reflected power is too high, the process will stop and the alarm will sound. Usually, if you still have high reflected power, the chamber needs to be cleaned. You can do this by running the batch named clean using the instructions above. You will want to remove your sample from the system before you do this.

If you are trying to run the system at a pressure you have never used before, and it still will not run after you clean it, this probably means that the system can not operate at the pressure you are using. You need to use another pressure. If you have run the system with the pressure and gas flows you are using before, contact MiRC staff for assistance.

Revision 1 - 15 April 1999, David Sigmon