Usage rules and instructions for the
AJA Ion miller Albanova (139)
Responsible:
Erik
Holmgren
- AJA International Orion ion mill with Kaufman 75mm ion gun
- Process gas: Ar
- Holder for max 100mm wafers, adapter for smaller chips
- Beam voltage up to 1000 V
- Acceleration voltage <200 V
- Max beam current dependent on beam voltage, max 290 mA at 1000 V
General Rules:
- No etching of toxic materials
- No unsecured/loose samples
- The ion gun must be purge and allowed to
cooldown after etching for at least 10 minutes
before venting the chamber
- The sample holder should be stored in the chamber,
and the chamber should be pumped after processing
Usage instructions:
Sample holder Loading/Unloading:
- Vent chamber by flipping the switch on the main rack labeled
VENT/PUMP to the off position
- Wait for the pressure to reach 100 Torr (1*10+2 on gauge)
then open manual vent valve fully and loosen the screw
on the door. Do not open the manual vent valve before
or the turbo can be damaged
- Wait for the pressure to reach 750 Torr, then open the door
- Screw the sample holder into/out-of the chamber-arm,
for easy access make sure the arm is tilted to -90 degrees.
The holder should be finger-tight, do not over-tighten
or the carbon backing plate can be damaged
- Shut off the manual vent valve, close the door and tighten screw
- Flip the switch on the main rack labeled VENT/PUMP to the
on position
- Wait until the turbo is at full speed (820 Hz) and the
pressure is below 5*10-6
Etching:
-
Make sure the turbo is at full speed (820 Hz) and the pressure
is below 5*10-6
-
Turn on the Kaufman power supply in the main rack,
wait for start-up routine to finish (about 10 seconds)
-
Make sure the Kaufman power supply is in remote and
auto mode (indicators on right-hand-side of power supply)
-
If necessary start the PhaseIIJ software and log in,
password is on the screen
-
Click "Run Process" and select the correct process,
then click "Open"
-
Wait for the process to finish
-
Make sure the required 10 minute flush at 50 sccm Ar starts
after the process finishes
-
Turn off the Kaufman power supply in the main rack
Sample mounting instructions:
Full 100mm wafers may be mounted directly on the sample holder.
-
Remove the six clamps along the holder edge
-
Place the silicone heat-transfer mat on the holder
-
Place wafer on the mat
-
Screw the six clamps back into place, tighten to finger-tightness
All samples smaller than a full 100mm wafer must be secured
on the chip-adapter
-
Remove the six clamps along the holder edge
-
Place the silicone heat-transfer mat on the holder
-
Place chip-adapter ontop of the mat
-
Screw the six clamps back into place, tighten to finger-tightness
-
Place sample on the adapter and secure with clamps
and screws from the box labeled "AJA mounting clamps"
in the LAF bench
Note:
If the screws securing the clamps are becoming
hard to tighten/loosen, do not force them in/out
contact the tool responsible
Making recipes:
Each process is comprised of several steps (referred
to as "Layers"
in the software). To make a new process click "Create Process"
on
the main screen to open the process creator, then select the layers
to add to the process, click add and then save the new process.
EACH PROCESS MUST END WITH THE "10 min Ar Purge" LAYER.
To make a new layer click "Create Layers" on the
main screen to open the layer creator. Turn on the desired
functions (for example Ar gas flow or substrate rotation)
and enter the desired parameters in the white boxes, then
click save and enter a new for the layer. The newly made
layer should now appear in the list of layers in the process creator.
The ion gun will not operate at arbitrary parameters and care
has to be taken to avoid damaging the ion optics.
To choose etching parameters, first choose a beam voltage
(lower voltage gives gentler etch), then set acceleration
voltage to at least 20% of the beam voltage, then set the
desired beam current below the maximum indicated in the table below;
| Beam voltage [V]
|
Minimum acceleration voltage [V] (must be <20% of V_beam)
|
Maximum beam current [mA]
|
|
400
|
80
|
55
|
| 600
|
120
|
120
|
| 800
|
160
|
200
|
| 1000
|
200
|
290 (special care required)
|
Some etch rates are indicated in the tables below;
Beam voltage 600 V, Acceleration Voltage 120, Beam current 120
| Material
|
Etch rate [nm/min]
|
| Si, SiO2, maN14xx, Cr (Edwards), LN
|
∼17
|
| Ta, W, TaN
|
∼5
|
| Cr (AJA1)
|
∼10
|
Beam voltage 400 V, Acceleration Voltage 80, Beam current 55
| Material
|
Etch rate [nm/min]
|
| Si, SiO2, maN14xx
|
∼5
|
| Ta, W, TaN
|
∼4
|
| Cr, LN, HfO2
|
∼7
|
| Ag, Au, Cu
|
∼30
|
| Mo, Al, Si-N
|
∼9
|
The etch rate depends on the angle of incidence, the rate
decrease as roughly the cosine of the angle. As the angle
is varied a mask will cast a shadow which limits the minimum
separation of objects, the shadow length is equal to the tangent
of the angle of incidence multiplied with the mask thickness.
The etching rate relative to 0 degrees angle of incidence and
the resulting normalized shadow cast by your mask is indicated
in the table below;
| Angle of incidence, a
|
Relative etching rate (cos(a))
|
Normalized shadow (tan(a))
|
| 0
|
1
|
0
|
| 15
|
0.97
|
0.27
|
| 30
|
0.87
|
0.58
|
| 45
|
0.71
|
1
|
| 60
|
0.5
|
1.73
|
| 75
|
0.26
|
3.73
|
| 90
|
0
|
inf
|
End of user instructions
Webmaster
Albanova Nanolab