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Revision 1 - 15 April 1999, David Sigmon

Plasma-Therm RIE #1

Trainers

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.

This RIE has two chambers. The left chamber is equipped with chlorine gases including boron trichoride (BCl₃), chlorine (Cl₂), chloroform (CHCl₃), and silicon tetrachloride (SiCl₄).

The right chamber is equipped with argon (Ar), trifluoromethane (CHF₃), oxygen (O₂), and sulfur hexafluoride (SF₆).

Operating Instructions

I. Loading

Operator Login

Login to the machine.
Press the ON button at the bottom of the screen.
Highlight Utilities, Select Active Chamber, and choose the appropriate chamber (depends on the process you are running!).
Press the STANDBY button at the bottom of the screen.
Highlight Utilities, Vent.
Listen for the sound the chamber venting. Once you hear a nitrogen escaping from the chamber, lift the chamber door. If the nitrogen does not turn off automatically, highlight Utilities, Close Gates.
Load sample into the center of the chamber.

II. Operating

If you do not already have a recipe, see the Recipe section of this document. Highlight Process, Load Recipe.
Press the READY button at the bottom of the screen.
After READY parameters have been applied, hold the chamber cover down and press the RUN button at the bottom of the screen. Note: you can step the first step of your process that lets the source cool down to the set temperature by pressing END STEP.

III. Unloading

After the process is over, press the STANDBY button at the bottom of the screen.
Highlight Utilities, Vent.
Listen for the sound the chamber venting. Once you hear a nitrogen escaping from the chamber, raise the chamber door. If the nitrogen does not turn off automatically, highlight Utilities, Close Gates.
Unload sample from the chamber.
Highlight Utilities, Pump Chamber.
Highlight Utilities, Logout.

Recipes

I. 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 gases 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.

II. Instructions

From the Process menu, choose 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 50mTorr 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 50mTorr. 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. If you set it to "Variable Time" you will be prompted for the process time each time you run your recipe. This is usually more convenient than editing the recipe each time. However, you can set the process to "Fixed Time" and set the time here if prefer.

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. The process pressure is measured in millitorr.

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 50 mT and set the time to ten seconds. The automatic vent feature does not work properly and should not be used. 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.

Using Manual Mode

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.