RIE
1C Operation Procedure
Tool
Power-up:
- Turn on the N2: above the tool on the
wall there will two valves. Open the valve to the left a few turns, but
don’t adjust the regulator to the right.
The regulator pressure should read about 14 psi.
- Turn on the cooling
water:
the blue water circulator to the left of the tool should be turned on
using the switch on the front of the tool.
- Open the process gas
valves:
open the oxygen tank by unscrewing the valve on top of the tank. Do not adjust the valves on the oxygen
regulator. Next open the valve on
top of the etchant gas, C3F8 octofluoropropane. DO NOT adjust the regulator valves.
- Turn on the Main Power
to the RIE-1C: Open the darkened translucent panel on the front of the tool and
press the green “On” button. This
will supply power to the tool and also turn on the power to the vacuum
pump and the RF generator. ***If
nothing comes one then check the breaker switch on the back of the tool.
- Check RF power
generator:
The front panel of the generator will light up when it is supplied with
power. If it is not lit then turn
on the power by using the power switch on the back of the RF generator,
which is located inside the base/cabinet.
If it does not light then contact the tool supervisor.
- At this point the water
pump should be running, the vacuum pump should be running, the nitrogen
ballast valve gauge on the vacuum pump should indicate that nitrogen in
flowing, and the RF power generator and the etching chamber segment should
indicate that they are supplied with power.
Running
a process:
- Determine the basic
process parameters: Gas flow values or the corresponding pressure values,
along with the amount of power to be used should be determined before
starting up the process.
- Opening the process
chamber:
once the tool is powered up, press the “start” button and then the “reset”
button on the front of the tool.
“Start” initiates the etch process by pumping down the chamber, and
“reset” interrupts the process and vents the etch chamber. After the chamber has fully vented an
alarm will sound which may be silenced by pressing the “reset” button.
- Load the substrate into
the etch chamber: making sure that it is in good contact with the underlying
surface and is within the circular area defined for substrate positioning.
- Close the chamber lid: after inspecting the
o-ring for particles. Any particles should be removed by gently wiping the
o-ring with a lint free wipe. Add a
sparing amount of vacuum grease if necessary.
- Set the process time: open the cover on the
front of the etcher and adjust the timer.
Adjust both the value and the unit to reflect the proper amount of
time. For example: 2 min could be
entered as 2 x m, 20 x 0.1m or 120 x s.
- Activate the gas valve
buttons:
GV1 and GV2 should be turned on (the green LED will light) in order to use
the corresponding gases. If only
one gas is desired then the other valve may be left in the off (unlit)
position. GV1 controls C3F8
while GV2 controls O2.
- Set RF power: Use the RF power
controller dial on the front left of the etching unit to select a setting
which has historically supplied the desired power level. Consult the process log for historical
data. For example: a setting of 546
on the RF power “odometer-style” dial will result in a power of
approximately 110W. The resulting
power level will not be visible until RF power is turned on after gas flow
stabilization.
- Press start: the valve between the vacuum pump and
the chamber will open and the chamber will be pumped down to 10
mTorr. Watch the pressure and be
ready when the chamber reaches this base pressure.
- Adjust gas flow: when the chamber pressure reaches 10
mTorr the gas flow will start but the RF power will not be turned on. Over the next thirty seconds gas flow
should be adjusted with the two gas flow needle valves on the front left
of the etcher. Using the needle
valve adjust the flow to the particular sccm rate or the pre-RF pressure desired(note: pressure will increase 5-10% with applied
RF power).
- Adjust RF power: after the gas flow
stabilization period the RF power will come on. Use the RF power dial to adjust the
forward (FWD) power level to the desired intensity. Next use the phase and then the load
dials to adjust the reflected (REF) power keeping it as close to 0 or 1 W
as is possible. Extremely short
etches may require a dry process run in order to set the RF power, lest it
be too unstable and disrupt the etch.
- Observe the plasma: Using the window near
the top of the front panel the purple glow of the plasma should be
observable. If the plasma
continuously flickers or appears unstable hit the reset button to abort
the process. Instability may be the
result of arcing, which can result in damage to the tool or poor etch
quality.
- Monitor the process: Particularly if the
process is long remember to periodically monitor the
etch for gas flow stability and RF stability. The process timer will indicate the
percentage of the time remaining.
- System Vent: When the time has
expired the RF power will be turned off, the gas valves, GV1 and GV2, will be close, and the chamber will be pumped back
to the base pressure value of 10 mTorr.
The chamber will then be vented to atmosphere with N2. When the venting is completed an alarm
will sound. This can be silenced by
hitting the “reset” button.
- Remove your substrate: after silencing the
alarm open the chamber lid and carefully remove your substrate being
careful to minimize scratches.
- Further Etching: if you wish to etch further under the
same conditions then place your next substrate into the chamber and hit
start, otherwise
return to #1 under “running a process”.
Powering
down the system:
- Unless you are going to
be using the system again in the next few minutes it is best to power off
the tool after pumping the chamber back down. The chamber should be held at vacuum
when not in use. This prevents the
adsorption of gas and water molecules, which are best left out and can
otherwise slow the pump down process.
- Turn off the GV1 and
GV2 buttons so that the associated LEDs are not lit.
- Turn off the RF power: using the toggle switch on the back of
the RF power unit(not the etcher itself).
- Close the lid and press
the start button: the system will pump down to the base pressure of 10 mTorr.
- Press the red Off button: on the front of the tool when the pressure has
reached 10mTorr. The power will go
off but the chamber vacuum will be maintained. Don’t wait longer for further pump down
as the tool will then enter into the normal process cycle. No gases will flow as long as GV1 and
GV2 are closed, but if the process is short it may vent the system once the timer has
expired.
- If you will be etching
shortly then you may choose to leave the main O2 and C3F8
cylinder valves open, the nitrogren line valve open, and the water
circulator on. If you have no plans
to use the tool in the next half hour then close or turn off these
components.