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Angstrom Thermal Evaporation Chamber
Standard Operating Procedure
Holmes Research Group
9/16/09
Purpose:
This document provides guidelines on how to properly operate and maintain the Angstrom
Engineering thermal evaporation chamber in Amundson 423.
(A) Chamber Control Software Operation:
Overview:
This software program is used to control the operation of the pumps on the Angstrom deposition
chamber. This program is used to pump down/vent the deposition chamber, perform a cryopump
regeneration, change set points and keep track of source materials in the chamber. The main
window is shown in Figure 1. The user name and login password are both “Operator”.
Figure 1: Main operating window of Angstrom control software
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Venting Deposition Chamber:
In order to vent the deposition chamber to atmospheric pressure, click on the “Auto Vent” button on
the main window. A new window will appear, click “Start”. The chamber will automatically vent to
atmospheric pressure. This process will take around 10 minutes when venting from chamber base
pressure.
Pumping Down Deposition Chamber:
In order to pump down the deposition chamber, click on the “Full Pump Down” button on the main
window. The chamber will automatically keep pumping until the cycle is changed. There is an
interlock in the software that will not allow a deposition to occur until the chamber pressure has
reached 8x10 -7 Torr. A typical pump down from atmospheric pressure to this interlock will take
around 15 minutes.
Cryopump Regeneration:
This cycle is only to be performed when necessary, as the temperature of the cryopump increases to
over 15K, or as needed. When this process is selected, the temperature and pressure of the
cryopump will be elevated to remove any trapped gases from the cooling element. The process is
automated to go through three cycles that flush out the pump and restore it to original operating
condition.
Source Detail and Shutter Controls:
This window (Figure 2) is used to keep track of the source materials currently in the deposition
chamber. Every time a material is replaced this window must be updated. This window is also used
to enable/disable substrate heating, substrate rotation and to control the shutter inside the chamber.
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Figure 2: Source detail and shutter controls software window
(B) Boat Positioning and Replacement:
Boat Types for Chamber Materials:
For different materials, we use a variety of boats. As a general rule, baffled boats are used for
organic materials, dimple boats are used for metals (besides aluminum) and LiF, and wire baskets
are used for aluminum. The boats used are ordered from R.D. Mathis Company. New boats should
be ordered when the supply is getting low to ensure that the next few users do not run out. See
Figure 3 below for the boats used and the corresponding model numbers for each boat.
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Baffled boat for organic materials, R.D. Mathis catalog # SB-6 and SB-6a
Tungsten wire basket for Al deposition, R.D.
Mathis catalog # B12A-3x.030W
Tungsten dimple boats for metal and LiF
deposition, R.D. Mathis catalog #S9C-.010W
Modified to 3.5 inches long
Figure 3: Boat types and ordering information
Boat Placement:
To reduce contamination the following material placement should always be used:
Source 1: Al
Source 2: LiF, Ag, Au
Source 3: BCP, BPhen, Alq
Source 4: TAZ, Blockers
Source 5: TPP, TCTA, TAZ, Hosts
Source 6: Donors: CuPc, SubPc, etc.
Source 7: Phosphors: FIrpic, Irppy, PtOEP, etc.
Source 8: Acceptors: C 60
If a new material is being placed in the chamber, consult other group members as well as Professor
Holmes to ensure proper placement of that material.
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Replacing boats:
Each source has a set two posts and clamps that hold the ends of a boat. To replace boats, simply
unscrew the wing nuts to loosen the clamps until you can pull the boat out. Re-usable boats should
be placed in aluminum foil and put away in their appropriate tray (the trays are labeled for all of the
materials in the chamber). Aluminum boats should be removed from the box and thrown away.
Slide the new boat into the clamps and tighten the wing nuts down. Make sure the boat is centered
in the clamps, otherwise it may get deformed and you may have poor electrical contact.
Replacing foil:
Between each source there are shields which help to prevent contamination between sources. Each
shield needs to be wrapped in foil to prevent material from depositing on the shields. In addition,
each time a material is switched, the foil on the shields adjacent to that source and the foil
underneath need to be replaced to prevent contamination. To replace the foil, slide the shield off of
its mounting bracket. Remove the old foil from the shield and from the glovebox. Place the new
foil on the shield making certain every bit of the shield is covered. Then proceed to slide the shield
back on to its mounting bracket. Make sure that the foil is tight to the shield and not obstructing the
deposition.
(C) Deposition Control Software Operation:
Overview:
The SQS-424 software is used to control the deposition of thin films in the Angstrom deposition
chamber. This software has three basic deposition modes: manual mode, automatic rate-controlled
mode, and automatic percent power controlled mode. This software displays information about the
current rate (Å/s), thickness (kÅ), power level (%), and quartz crystal monitor (QCM) lifetimes (%)
(see Fig. 4). The username for this software is “Super” (there is no password so leave it leave
blank).
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Figure 4: Deposition software main screen
Setting up a new material:
Before a deposition can be done with a new material, several program parameters must be defined.
First, under “Edit” “Material” a material profile must be defined. This profile includes the
material name (i.e. “Aluminum”), the material density (1.1 for most organic materials), and Z factor
(1 for most organics); when finished editing, close the box to save the material profile.
Next, under “Edit” “Films” create a “New” film, enter the film name with the material followed
by the source, (i.e. BCP Src 3). Several entries must be made to define the film:
Deposit: P: 100
I: 10
D: 0
Shutter Delay:
“Enabled”
Accuracy: 20%
Wait: 60 seconds
Hold: 3 seconds
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Rate Sampling:
“Continuous”
Accuracy: 5%
Sample: 10 seconds
Hold: 10 seconds
Condition: Pre Condition:
Ramp1 Pwr: 0
Ramp1 Time: 0
Soak1 Time: 0
Ramp2 Pwr: Power level at which the organic begins to sublimate (typically 10-
15% for organics but depends on the sublimation temperature
of a particular material)
Ramp2 Time: 180 seconds, this is how long the system takes to ramp up the power
from 0% to the Ramp2 Pwr level
Soak2 Time: 180 seconds, this is how long the system will wait at the Ramp2
Pwr setting, before beginning the “shutter delay” phase
Condition: Post Condition:
Ramp Time:
Everything else: 0.
30 seconds, this is how long the system will take to ramp the power to
0%, from the deposition power
Source/Sensor:
Material:
Select previously defined material profile
Max Power: 30% for organics (possible higher for metals)
Slew Rate: 4%
Sensor Tooling(%): New tooling factor (in appropriate QCM position; i.e. sources 1 and 2
use QCM # 1, 3 and 4 use QCM #2, etc; QCM positions 5-8 are not
used)
Errors:
On Error:
Crystal Fail:
Control Error:
Crystal Quality:
Crystal Stability:
“Stop Layer”
“Enabled”
5%, 5 seconds
5%, 5 seconds
1000 single Hz, 5000 total Hz
Now that a material profile and film have been defined, a Process can be programmed (“Edit”
“Process”).
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(1) Uniform Films:
For a single, neat layer, begin by creating a “New” process and naming it after the material and
source (i.e. BCP src 3). There are many options and parameters under each of the following
headings (See Fig. 5):
Layer:
Figure 5: Process edit window
Film:
Output:
Input:
SetPt:
Final Thick.:
Time EndPt:
Thk. EndPt.:
System Setup:
Source:
Substrate:
User1:
User2:
Manual:
Select previously defined film (name should match process)
Select the appropriate QCM for the source.
Select “Sensor(s)”
This is the target rate for the deposition (Å/s)
This is the target final thickness of the film (in kÅ)
This parameter is not used for neat layer growth (leave blank)
This parameter is not used for neat layer growth (leave blank)
Default.
This must match the source where the material is placed in the
chamber
None
None
None
Checked (instead of Auto Start or Continuous).
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Rate Ramps: (not used during neat layer growth):
Start Thickness:
Ramp Time:
SetPt:
Deposit:
Condition:
Source/Sensor:
Error:
0 kÅ
0 sec.
0 Å/s
These settings should automatically match the parameters defined in
the “Film” (ensure shutter delay is enabled).
These settings should automatically match the parameters defined in
the “Film”.
These settings should automatically match the parameters defined in
the “Film,” check to make sure “material” is correct.
These settings should automatically match the parameters defined in
the “Film”.
To save the process, close the box, a message will appear asking, “Do you want to change the
Operating Process to [your new process]? Answering yes will make that process the active one,
answering no will not change the active process, but will still save the new process.
Preparing for a deposition:
To deposit a neat film, select “Edit” “Process” and choose the appropriate process. Under the
layer tab, select the target rate and thickness, and ensure that the proper QCM (output) and source
(1-8) are selected for your material. Under the “Condition” tab, select an appropriate “ramp2 pwr”,
“ramp2 time”, and “soak2 time” (typically 10-15%, 180 sec., 180 sec.). Under the “Source/Sensor”
tab enter the new tooling factor. To save the changes, close the window, answer yes to make the
process the active operating process. To begin the ramp-up, click the “Start Layer” button (should
be green). The software will automatically begin to ramp up the percent power to the boat up to the
“ramp2 pwr” value entered in the process window while displaying the rate of deposition. The
“ramp2 pwr”, as well as “ramp2 time” and “soak2 time” are displayed to the right of the time vs.
rate graph, and are modifiable at any point in the deposition.
Manual Mode: Select the (gray) “AUTO MAN”. Doing this will immediately
open the shutter and allow deposition to proceed until the “Final Thickness” value of
the process is met. This mode allows the user to manually adjust the percent power
to the boat, this value as well as the current power is displayed to the right of the
time-rate plot and can be modified at any point; it is in this way that a target percent
power deposition is made, the software will hold the set power level until deposition
is complete regardless of other settings (except when an error is triggered).
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(2) Doped Films:
Automatic Mode: Allow the power to ramp up to the “ramp2 pwr” level while
watching the rate; if at any point during this process the rate spikes to undesired
values, scale back the ramp2 power value using modifiable value to the right of the
rate-time plot. Once the ramp2 time has expired, the program will enter the “soak”
phase. In this phase the user actively monitors and modifies the ramp2 pwr level
until the desired deposition rate is met and is steady. Modifications can be done by
typing in desired power levels or by selecting the current value and using the arrow
keys on the keyboard to make progressive adjustments. Once the rate is stable, set
the “soak2 time” to zero and press enter, this will force the software into the “shutter
delay” phase, where it monitors the rate to make sure it is steady and at the rate
defined in the process. If these conditions are met within 60 seconds (typically takes
~5 seconds), the shutter will open and the software will enter the deposition phase (if
the conditions of the shutter delay are not met, the software will end the deposition
entirely, and will immediately set the power level to zero). Once in the deposition
phase, the software will automatically attempt to hold the desired rate by adjusting
the power, while monitoring the deviation from the desired rate (in %), the total
thickness deposited (in kÅ), and the current power level (in %). At any point the
user may select into, and out of, manual mode if necessary (i.e. particularly unstable
rate, etc.). Once the thickness reaches the “Final Thick.” defined by the process, the
software will enter the post deposition phase, close the shutter, and ramp the power
level to 0% (in 30 seconds, if set properly). Once the feed time has expired, the
program will revert to its default, idle state.
To define the process for a doped layer:
1) Define a process for a neat film (say CuPc Src4).
2) Select the first layer by clicking on “Copy Layer” and then select “Paste Layer”. This will create
a copy of the previously defined process.
3) Edit the parameters of the second layer to those of the doped layer (say C 60 Src8). Make sure that
you change the “Film”, “Output”, Input” and “SetPt” in the “Layer” tab of the deposition software.
The rate for the materials is decided based on the composition of the film that you want. For
example, if you want 20% of CuPc and 80% of C 60 in the film and you want to grow the film at a
total rate of 2 Å/s, then the SetPt for CuPc will be 0.2x2 = 0.4 Å/s and the SetPt for C 60 will be
0.8x2 = 1.6 Å/s.
4) After changing the parameters of the second layer, select the second layer and click on “Cut
Layer”.
5) Then click on “Paste Codep”.
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This will define the process for a doped film. Growth part for a doped film is similar to that of a
neat film except for the fact that in the case of a doped film, you will have to manage two deposition
rates at the same time instead of one.
(3) Gradient Films:
The process definition for a graded layer is slightly different from the process for a uniform layer.
In this case, you need to define the initial growth rate, final growth rate and the ramp time for the
process.
Layer:
SetPt:
This is the initial growth rate of the gradient
(All the other parameters are defined in the same way as for a uniform film)
Rate Ramps: (used for growing gradients)
Click on “InsertRamp” and then define the following parameters in the process.
Start Thickness:
Ramp Time:
SetPt:
0 kÅ
Include the ramp time (See comments below)
This is the final growth rate of the gradient
(All the other parameters are defined in the same way as for a uniform film)
Comments on growing a gradient:
The initial growth rate (r 0 ), final growth rate (r f ), thickness of the film (Th) and ramp time
(T) are the variables involved in the growth of a graded structure. Since, r 0 , r f and Th are known, the
rate is given by Eqn. 1:
r = a + b× t
(1)
where r is the growth rate (Å/s), t is the time (sec), a and b are constants.
At time t = 0 , r = r0
⇒ a = r0
(2)
At time t = T , r rf
=
f
⇒ r = a + b× T
(3)
Finally, the thickness of the film is given by,
T
T
∫ ∫ (4)
Th = rdt = ( a + b×
t)
dt
0 0
Solving Eqns. 2-4 for three unknowns a, b and T, we get:
a = r 0
;
( rf
− r0 ) × ( rf
+ r0
)
b =
;
2×
Th
T
2×
Th
=
( r + r )
f
0
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(D) Maintenance/Utilities:
Nitrogen Gas Line:
A nitrogen gas line is supplied to the Angstrom system. This is used during the venting of the
cryopump regeneration process. This line is fed from gas that is boiled off of the liquid nitrogen
tank on Amundson. The typical pressure reading for this line is 20 psi.
Compressed Air Line:
The Angstrom system uses compressed air to operate the valves on the system. The compressed air
is supplied through the utilities of Amundson. The typical pressure reading for this line is 90 psi.
Cooling Water Overview:
The chamber requires cooling water to keep the working temperatures of internal components and
the quartz crystal monitors (QCM) down. The cooling water is provided from a chiller that is
located in the penthouse of Amundson, this chiller is shared with Leighton and Norris research
groups. The cooling water consists of a 50/50 mixture of water and ethylene glycol (antifreeze).
The filter in 423 is the only filter on the system to remove debris from the cooling water lines. Over
time the filter will become saturated and will decrease the cooling water flow rate. Our system
requires a flow rate of 2.0 GPM to properly cool the equipment. If the flow rate drops much below
this value the filter must be replaced. Filters are standard home water system filters that can be
purchased at Home Depot.
Cooling Water Filter Replacement:
1) Turn off the water supply to the filter. This can be accomplished by turning the control
handle on the filter assembly to the off or bypass position.
2) Place a bucket under the filter assembly to catch any spilled fluids.
3) Press the red button on the left side of the assembly to remove pressure from the system.
4) Unscrew the filter canister and remove the old filter.
5) Inspect the condition of the o-ring, replace if needed.
6) Place a new filter cartridge into the filter canister, ensuring that the filter is properly seated.
7) Screw the filter canister onto the assembly.
8) Slowly rotate the control handle back to the filter position.
9) Press the red button on the left side of the assembly to remove any trapped air.
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Replacing Chamber Electrical Fuses:
Occasionally, a deposition source electrical fuse blows and must be replaced. When this occurs the
deposition rate will immediately fall to zero or a rate will never be able to be reached regardless of
the power. To check and change the fuse, perform the following steps:
1) Remove the front plate of the deposition chamber which is located towards the solvent fume
hood underneath the glove box.
2) Unscrew the black knob and slowly swing the electrical compartment door open.
3) Do not touch anything inside the chamber electrical compartment other than the fuses and
their holders.
4) Along the top of the left wall of the electrical compartment there is a bank of white plastic
compartments with orange lights on them. Locate the one with the orange light that is on.
This is the fuse that needs to be replaced.
5) Swing the compartment down to open it and remove the old fuse.
6) New fuses are in the top right drawer of the cabinets near the cooling water filter. Place the
new fuse where the old fuse was removed.
7) Close the plastic fuse compartment and make sure the light turns off.
8) Close the electrical compartment door and tighten with the black knob.
9) Fasten the face plate back on the chamber.
If you open the electrical compartment and find that a fuse is not blown, check your boat
connections to make sure they are firm. Often times this will result in the same symptoms as a
blown fuse.
Changing Oil in Rough Pump:
This should be done on an as needed basis when the color of the oil starts to become cloudy and is
no longer transparent. When doing this also inspect the condition of the oil mist filter, replace as
needed.
1) Make sure all pumps are turned off
2) Allow the rough pump to cool
3) Place the oil waste container under the rough pump oil drain port
4) Remove the plug and allow for all of the used oil to drain from the pump
5) Replace the oil plug
6) Fill the pump with new oil up to the full line. Typical oil used is TKO-19 ultra from Lesker
or equivalent.
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