Introduction:
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The Auto is a single chamber 4” barrel asher,
with a 300W RF maximum power supply, generating an air or oxygen
plasma. Plasma causes chemical and kinetic energy to either modify
the top levels of a substrate surface, if Using lower energy air
plasma, or to removal organic materials, such as photoresist, if
Using higher energy O2 plasma, on substrates no larger than 4”.
Lower pressures equate to higher energies due to fewer inter gas
collisions.
Typical usages of low power are PDMS to glass bonding,
often done for .2 min. (12 sec) at 100 W in air at 1 torr, and
high power is typified by resist ashing done at 200 W and .5 torr,
with time depending on resist thickness. RF Power of up to 250
or even 300 W can be used for short periods, but causes exhaust
overheating after about 5 minutes. |
Procedure:
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Standby Condition at Beginning and End of the Run:
Buttons: “AC”, “Vacuum”, are “ON” and “Tune” is “Auto”,
door latched, coral disengaged.
- Engage in CORAL, which will turn the system ON.
- Spin “Selector” dial to “RF Set Point” and
dial in desired power. Use 0 power for the dummy run.
- Set timer to desired time, in minutes.
- Open the correct toggle valve; #1 for O2 or #2 for air.
- Vent the chamber by pressing the “Vacuum” to “OFF”,
which takes ~30 sec.
- Unlatch the perforated metal door, remove Quartz chamber door,
and clean the chamber carefully with a lightly wetted fabwipe,
taking care not to break the gas feed tube along the top of the
chamber, then return quartz door and re-latch interlocked metal
door, and press vacuum “ON”.
- Dummy Run: Used to verify the pressure is set correctly: Set
Time and RF Setpoint, then leave slector knob at “Pressure”.
Turn ON either O2 or Air toggle switch, and turn the Vacuum ON:
- Press “Process Start”. When the pressure
drops below ~.5 T, the Opened gas will start flowing, and
you should then adjust the flow rate with the knob under
the toggle selected, to yield the desired chamber pressure.
- Spin the selector knob to verify RF Reflected Power is ≤ 1
and power level is correct, then press “Process Abort” and
then “Vacuum OFF”.
- Actual Run:
- Load samples into chamber, and press Vacuum “ON”. Small
or messy samples like PDMS may not touch the side of the chamber
wall, but instead must be mounted on glass slides. Surfaces
to be treated should be clearly exposed to the plasma in the
center of the chamber.
- Pump down the chamber to the desired base pressure, e.g.
0.2 T for an O2 plasma process but not being critical for an
air plasma process, and after setting the actual RF Setpoint,
press “Process
Start” button, taking the process through to completion.
- When done, press the “Vacuum OFF” and unload
after venting, but if running for more than 30 minutes, allow
your sample to cool for 5 additional minutes.
- Return machine is in “standby” condition, per above
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