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Plasma lab Oxford Instruments Plasma Technology System Manual Check that plasma is striking - try high pressure strike (>SOmT RIE, >8mT ICP), or increased RF power input, or addition of more DC bias Try selecting &…

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System
Manual
Oxford
Instruments Plasma Technology
Plasma
lab
3.4
Process
troubleshooting
3.4.1
Partial
process
failure
3.4.1.1
Example
problems
• Etch rate has
dropped
• Selectivity reduced
•
Profile
no
longer
anisotropic
•
Non-uniform
etching
(or deposition)
3.4.1.2
Typical causes
•
Hardware
has changed -
new
gas cylinder,
new
cover plate,
RF
connection /
grounding
is
faulty.
• Chamber leak - Check leak-up
rate
• Faulty
MFC
- check
partial
pressures
•
APC
cannot
control
pressure - check
MFCs
/ Pumps
•
RF
generator/matching
- adjust
matching
unit
set-up, check
generator
range switch,
watch
HF
matching
time
in
mixed frequency pulsed process
• Incorrect gases used
•
Temperature
-
poor
clamping / cooling, e.g. particles
on
electrode/wafer,
lift
pin
not
fully
down,
wafer
piece
not
glued
to
carrier, incorrect set-up
of
Eurotherm,
high
power,
or
poor
resist
preparation
• Chamber
is
dirty
- needs
more
frequent
cleaning
• Incorrect process
regime
(knife-edge
process)
•
Wrong
hardware
for
given process -
wrong
cover plate,
wafer
not
being cooled / heated
sufficiently,
wrong
electrode
gap
•
Wrong
process
for
given
hardware
-
no
pumpdown
time,
no
preheat
step,
no
pre-clean step
3.4.2 Total process
failure
3.4.2.1
Example
problems
• Process
not
etching
/
depositing
- does plasma
ignite?
• Plasma does
not
ignite/light
up
• Plasma
is
unstable/pulsing
• Plasma
is
flickering
3.4.2.2
Typical causes
Check
that
readbacks are
within
tolerance -
MFCs,
pressure control,
RF
matching,
temperature.
Check
that
base pressure has been reached (this can always be changed
if
you are
in
a
hurry!)
Read
error
/
warning
/
information
messages
Process
Information
(Information
contained
in
this
document
is
confidential)
Printed:
08
January
2006 09:37 Page
23
of
30
Issue
1:
December 03
Plasma
lab
Oxford
Instruments
Plasma
Technology
System Manual
Check
that
plasma
is
striking
-
try
high
pressure strike
(>SOmT
RIE,
>8mT
ICP),
or
increased
RF
power
input,
or
addition
of
more
DC
bias
Try selecting
'ignore
tolerance'
checkbox
Sudden pressure rise - check
for
dissociation, -
try
Ar
instead, strike
at
reduced
ICP
power
Sudden pressure rise
at
plasma strike - check
for
cross
talk
between
RF
power
and CM
gauge
Sudden
temperature
rise
at
plasma strike - check
for
cross
talk
between
RF
power
and
temperature
gauge
Sudden gas
flow
change
at
plasma strike - check
for
RF
cross
talk
Process
Information
(Information
contained
in
this
document
is
confidential)
Issue
1:
December 03 Page 24
of
30 Printed: 08 January 2006 09:37
System
Manual
Oxford
Instruments
Plasma Technology
Plasma
lab
4 Glossary
of
terms
AMU
APC
Backing
pump
Backing valve
Baratron
Base
pressure
Bayard-Alpert
gauge
Clean gas
Cluster
CM
gauge
(Baratron)
Cryo
pump
(Meissner
coil)
Driven
electrode
DSflW
ECR
Abbreviation
for
Automatch
Unit. This
is
a
self-controlling
variable capacitor,
which
is
connected
between
an electrode
(to
which
it
is
normally
close-coupled)
and
the
discharge
power
supply. Its purpose
is
to
shift
the
voltage
and
current
waveforms
to
maximise
the
power
transfer.
It
also transforms
the
load
impedance
to
son.
Abbreviation
for
Automatic
Pressure Controller. Refers
to
a variable
conductance valve, which,
under
the
control
of
a closed
loop
feedback system,
controls
the
chamber pressure. The
controller
is
a
remote
electronic
module
with
inputs
from
a chamber pressure gauge, and
from
the
system master
controller.
A
pump
in series
with,
and
downstream
of,
the
main
high
vacuum
pump.
(See
also Rotary
pump)
The valve which,
when
open, allows
the
backing
pump
to
pump
gas
from
the
main
pump.
See
CM gauge. Baratron
is
a
trade
name.
The
lowest
pressure
attainable
by a
high
vacuum pump.
Alternatively,
the
pressure,
which
should be
attained
before
starting
a process.
See
Ion
gauge
This refers, in fact,
to
'cleaning gas'.
It
is
a gas which,
when
converted
to
a
plasma, removes
contamination
from
the
walls
of
the
chamber and
from
the
electrodes.
An
array
of
processing chambers
around
a single load lock chamber housing a
substrate-handling
robot.
Capacitance
manometer
gauge
in
which
gas pressure deflects a
membrane
and
thus a measured capacitance. Measures absolute pressure
down
to
approximately
10-
5
Torr.
Not
affected by corrosive gases. Does
not
need a
correction
factor
for
different
types
of
gas.
These pumps
trap
gas
on
a very cold surface. They usually consist
of
a closed
circuit
helium
refrigeration
system. They
require
periodic regeneration,
during
which
they
cannot
be used
for
pumping.
Base
pressure
approximately
10-
9
Torr.
The electrode
to
which
the
electrical discharge
power
is
applied. The
other
electrode may be
either
earthed
or
at
floating
potential.
An
abbreviation
for
the
Downstream
Microwave
process.
An
abbreviation
for
the
Electron Cyclotron Resonance process.
Process
Information
(Information
contained
in
this
document
is
confidential)
Printed: 08 January 2006 09:37 Page
25
of
30
Issue
1:
December 03