LFE Barrel Plasma System

Trainers

The LFE barrel etcher is usually used for removing photoresist layers and other simple sample cleaning operations.

Overview of Controls

Barrel Etcher Top

The main control panel is used to perform most sputterer operations.

Barrel Etcher Bottom

The main control panel is used to perform most sputterer operations.

Operating Instructions

Turn on the pump power, followed by the system power (both are located in the lower right corner of the unit).
Wait until the chamber has purged and the pressure reads 760 torr. At this time you should place your sample into the boat that is inside the chamber. NOTE: A display check and alarm sound will accompany the proper closing of the chamber door. Be sure the door is properly closed.
Set the process time using the controls in the upper left hand corner.
Select a gas by putting switch in up position. Be sure that the gas flow is open. The flow will not register on the gauge until after the preliminary pump down, so it is quite difficult to set at a particular flow until that time.
Press the start button to begin the process. DO NOT OPEN THE CHAMBER DOOR ONCE THE PROCESS HAS STARTED. If you need to open the chamber door press the stop button and wait for the chamber to vent! The chamber will pump down to .1 torr and then automatically allow the process gas into the chamber.
When the process time begins and the plasma begins to form the alarm will sound and the display will ask you to tune. Rotate the tuning knob on the unit (located in the lower left) until the display shows the fewest number of bars. Do not rotate the knob too far in either direction, as improper tuning will abort the process. If tuned properly forward value will be much greater than the reflected (this can be tested with the switch under the display).
After tuning, the RF power can be adjusted with the knob located next to the tuning knob. As the power is adjusted, tuning again becomes necessary.
When the process has been completed, the alarm will again sound and the chamber will pump down and vent, pump down and vent again. When the chamber returns to 760 torr, the alarm will sound a final time for 15 seconds, and the "END CYCLE" display will appear. When the alarm has finished sounding the chamber door may be opened and the sample removed.
Close chamber door, put all gas select switches in down position, and turn off the power to the pump and system when your work is completed.

Troubleshooting

The barrel etcher keeps aborting because the reflected power is too high.

This means that the etcher is not tuned right. Try to restart it and tune it. Look at the pressure. If you are trying to run the barrel etcher at a pressure or with a gas mixture that you haven't used before, the etcher may be unable to tune with the settings you are using. If you are sure that it has run at that pressure, gas mixture, and power before it may simply be too far out of tune to tune easily. If it is far out of tune, it may be hard to get it in tune before it aborts. Usually, if all else fails, and the barrel etcher can actually run at the settings you want, you can tune it like this:

First, if you have a sample in the chamber take it out.
Try running the barrel etcher with the power turned all the way down, and using CF₄ and O₂ with each gas set at about half of the flowmeter scale. Don't worry if these are not the gases you are using. We will change the gases later. It is easier to tune it with this mixture. Also, set the timer for a long time so that it won't shut off while we are tuning it.
When the etcher beeps and turns the power on tune it for minimum reflected power. Then turn the power up until the reflected power begins to increase. Then try to minimize the reflected power again. Keep doing this until you get to the power you want to use. As you pass through the 50 W - 100 W range, it will be impossible to keep the reflected power low. Just try to keep it low enough not to abort. As you get above this range, it should be possible to get the power lower.
At this point, the barrel etcher should be running at the power you want, but the gas mixture is still wrong. Slowly adjust the gas mixture while tuning to keep the reflected power low until you reach the gas mixture you want. After you have the barrel etcher running at your desired settings, press STOP to turn it off and try your run again.

I can't change the third digit of the time. It is stuck at 5.

There isn't much you can do about this. It has been stuck there for a long time.