Chapter 5.36
YES Vacuum Oven
(vacoven)
1.0
Title
The YES
(Yield Engineering Systems) Vacuum Cure Oven
2.0
Purpose
The YES oven can be used for curing of polyimides, anneal processes, and other materials which require elevated temperatures of up to 450°C and controlled atmosphere (N2 or O2) of between 200 and 400 Torr.
Note: YES field engineer recommended N2 pressure between 200 and 300 Torr. Lab members are encouraged to give more inputs as more usage of the oven develops a more mature process.
3.0
Scope
This document describes the operational procedures for the YES oven standard programs (1 - 5); how to enter new programs what materials are allowed and/or forbidden in the oven, as well as user-level troubleshooting guidelines for the tool.
4.0
Applicable Documents
There are two manuals for the YES oven available upon request in the
Microlab office.
4.1
The
Partlow MIC 1460 operator manual details the use and programming of the Partlow
temperature controller.
4.2
The
YES-450PB6 / 8-2P-CP operator manual is more focused on the use of the touch
screen panel on the system controller.
(There are some inconsistencies between the
YES manual and the Microlab tool since this YES oven had been customized
by its previous owner.)
4.3
There
is also a two-page roster of recommended machine settings provided by the
factory, which is to be used by the maintenance personnel only.
5.0
Definitions & Process
Terminology
5.1 Control unit: It sits on top of the oven and houses, among other things, the
Partlow temperature controller, the QuickPanel jr. touch screen controller, the
Convectron Gauge and the big red emergency stop button.
5.2 Partlow: A third-party temperature
controller installed in the control unit. This is where temperature as a
function of time portion of a process program is entered. (Process gas selection
is done on the touch screen and process pressure is specified using a
combination of the touch screen and a manually adjustable vacuum throttle.)
5.3 Convectron Gauge: Granville Phillips 275 Convectron Gauge
displays the status of the chamber pressure.
5.4 Touch Screen: QuickPanel jr. touch
screen controller by Control Technology Corporation displays the process
status, alarm warning messages, input number of dehydration loops, input time
to reach process pressure, vacuum and gas selections.
5.5 House Vacuum: One of the two vacuums used to pump down the vacuum chamber. The
house vacuum, located in the rear of the oven, has a throttle valve installed
between the pump and the oven. If
decided to use the house vacuum, adjusting this valve is one way of obtaining
the desired process pressure.
5.6 Main Vacuum: The other vacuum used for pumping down the vacuum chamber. It
uses the same rough pump as the house vacuum and is connected in parallel with
the house vacuum to the oven. The main
vacuum is not throttled and should be selected when lowest pressures are
desired. (To maintain the pressure of
200 to 400 Torr during a N2 anneal
process, it must be left ON until further testing.)
5.7
Dehydration Loops:
Pumps and N2 purges performed at the start of any process used to remove
moisture and oxygen from the chamber, prior to starting an anneal process. You
may specify how many dehydration loops to execute for your process. Please,
note that the temperature program, as
specified on the Partlow, does not wait for the dehydration loops to complete
before executing your process. You must factor the time it takes for the
dehydration loops to execute into your (temperature) program. Each loop takes
about ~ 1 minute 15 sec. Based upon 3 dehydration loops, the amount of oxygen
from room air left in the oven is estimated at 10 ppm.
5.8
Thumbwheel settings:
Position of the numbered index wheel on the far right of the oven
control panel. Position 0 = chamber vacuum; Position 1 = unit under control of
Partlow temp controller; Position 2 = chamber backfill; Positions 3-9 not
active.
6.0
Safety
Burn Hazard.
Items can be dangerously hot coming out of the oven. The oven walls will also
be hot. Wear appropriate hand protection and watch that you do not brush your
arm against the oven walls (especially the inside of the oven door) when you
unload your wafers.
7.0
Statistical/Process Data
N/A
8.0
Available Processes, Gases, & Process Notes
8.1
Available Processes
The YES oven has three major process
offerings: Polyimide cure, Anneal,
Oxidation. Programs 1 – 5 and can be used for these processes. They are not to
be changed by the user. Programs 6 – 8, on the other hand, are designated for
user modification. Note these Program numbers refer to the Partlow temp
controller program number and are not to be confused with the thumbwheel
positions. The oven will follow Partlow temperature control only when the
thumbwheel is set to position 1
Detailed time and temp information for all programs below is in Section 12.4.
8.1.1
Standard
PIMD multistep anneal Program #1 at 450°C in YES manual
8.1.2
Program
#2 - 200°C, 30 min anneal
8.1.3
Program
#3 - 300°C, 30 min anneal
8.1.4
Program
#4 - 400°C, 30 min anneal
8.1.5
Program
#5 - multistep 350°C, 30 min anneal
8.2
Available Gases
8.2.1
Hot
and Cold Nitrogen
8.2.2
Oxygen
8.3
Process Notes
8.3.1
The
standby temperature of the YES oven is currently set to 32°C.
8.3.2
The
oven is configured to operate at temperatures between room temperature and
450°C. Attempts to exceed this temperature will fail with an alarm.
8.3.3
The
system is optimized for operation between 300 and 450°C. This is where minimum
temperature overshoot (< 15°C typically) will occur.
8.3.4
To
prevent chamber oxidation, do not use oxygen for processes to go above 300°C
without consulting a process engineer.
8.3.5
Granville
Phillips convectron gauge set point 1 = 50 Torr and set point 2 = 500 Torr.
8.3.6 N2, house vacuum and main vacuum valves are preset to obtain 200 to 400 Torr, as recommended for the standard polyimide curing process.
9.0
Operating Procedure
9.1
Enable
the system on the Wand.
9.2
Check
the chamber pressure on the convectron gauge.
Note: Make
sure oven pressure is 760 Torr so that you can open the chamber door (if not,
dial thumb wheel to 2 and press Start. It will inject N2 into the chamber to
vent the oven).
9.3
Make
sure the thumbwheel dial is set at 1.
If not, change it to 1.
9.4
Load
samples into oven.
Note: You may use a metal cassette,
quartz or graphite boat, when loading wafers. Two 4” black anodized aluminum
cassettes are provided. You may NEVER
use plastic (including Teflon™) cassettes nor put plastic into the oven. If you
need to use other fixtures for your samples, get permission from Bill Flounders or Sia Parsa.
9.5 Press PROF
button until the desired program number is selected on the Partlow temperature
controller.
9.6 Press the OPERATOR
PANEL button until the PROCESS PARAMETER SELECT PANEL page is
displayed on the QUICKPANEL, jr. touch screen panel. On the process parameter
select panel, you must indicate the following process details:
9.6.1
DEHYDRATION
VACUUM SELECT – This is the vacuum to be used for the dehydration loops. Choose
between house vacuum (throttled), main vacuum, and both vacuums. Recommended
setting: both.
9.6.2
RAMP
UP PROCESS GAS SELECT – This is the gas to use whenever the temperature of the
oven is increasing. Choose between cold N2, Hot N2 (gas is circulated through
heating coils before entering the process chamber), Gas2 (currently oxygen -
need to open main valve on wall), After usage, please close main valve on
wall.), or Gas3 (no gas connected to Gas 3 - do not use). Recommended – hot N2.
9.6.3
DWELL
PROCESS GAS SELECT – The gas to use whenever the oven is programmed to sit at a
given temperature. The choices are the same as above. Recommended: Hot N2 or O2
depending upon desired anneal process.
9.6.4
RAMP
DOWN PROCESS GAS SELECT - This is the gas to use whenever the temperature of
the oven is decreasing. Choose between Hot N2, Cold N2 (gas is at room
temperature), or both. The heater is actually turned off in the cool down
steps. You may select both if you want the greatest amount of room temperature
for N2 to cool off your samples.
9.6.5
PROCESS
VACUUM SELECT – This is the vacuum to be used after the dehydration loops to,
until the selected program has ended. Choose main vacuum or house vacuum
(throttled) or both. If you want the lowest possible pressure, choose both to
keep the main vacuum valve open. If you want a higher pressure, choose house
vacuum and throttle it as needed at the valve for your process. But process
pressure must be less than 500 Torr.
After your process, you must adjust the throttle valve back to its
original position. . The default throttle valve position provides process
pressure between 200 to 300 Torr.
9.6.6
# DEHYDRATION
LOOPS – 3 loops are recommended. Press ENTER
# OF DEHY LOOPS button on the touch screen panel. Press 3, or the number of
loops you decide on (maximum dehydration loops are 9), press ENTER, and
then press DONE.
9.6.7
TIME
TO REACH PROCESS PRESSURE – The time to wait for the oven to pump down to below
500 Torr. Recommended time: 120 sec. Press TIME TO REACH PROCESS PRESSURE
button on the touch screen panel. Enter 120 or your desire time (maximum is
360 sec.); press ENTER, and then press DONE.
9.7
Make
sure the touch screen displays READY TO PROCESS before starting the
process. If not, press the OPERATOR PANEL to return to the main status
screen manual and the READY TO PROCESS will display.
9.8
Press
the big black START button on the system controller.
Note: To start the process, DO NOT
press the RUN/HOLD button on the Partlow. Doing so will do nothing.
9.9
When a
message on the touch screen said that the process is complete, press the big
red RESET button on the system controller.
Note: The wait time for the chamber to
ramp down to set point, may take many hours. Therefore, you can vent the
chamber when the temperature drops to 120°C on your cooling step (abort your
process). You can vent the chamber by setting the thumbwheel to 2 and press the
big black START button. Do not open the oven with temperature >150ºC.
You can be seriously burned if the chamber is open when too hot.
Note: You may press the big red RESET
button anytime to abort your process.
9.10
Unload
your wafers.
Note: Use the high temperature dedicated mits
to unload the anodized cassette when it is hot. Careful! You must have a
good grip on the cassette when unloading it.
9.11
Leave
the oven pumped down when not in use. Set thumbwheel to 0 (pump down) and press
START button.
Operational
Notes:
The thumbwheel
has three settings.
0 – Pump
down chamber
1 – Ready
to execute selected Partlow program
2 – Vent
the chamber
(Press the
big black START button to execute the job.)
If you
want to skip a segment on the Partlow temperature program while your process is
running, you may do so by pressing the UP ARROW button and the SCROLL
button at the same time.
Chamber
pressure has to be above 500 Torr to start a process.
10.0
Troubleshooting Guidelines
10.1
Alarm
is sounding.
10.1.1
Press ABORT
to silence alarm.
10.2
Process
is aborted with an HBA alarm.
10.2.1
A
Heater Break Alarm indicates that the heater coils are not drawing current.
This is a symptom that the coils are burnt out, or that a relay is burnt out,
or that the PID temperature control setting have been altered. Report a Fault.
10.3
Process
is aborted with an over temp alarm.
10.3.1
The
process temperature has exceeded 462°C. The YES does not permit temperatures
above 450°C to be entered. If you get this alarm, then it is probable that the
PID settings have somehow changed and the oven temperature is over-shooting.
Report a fault.
10.4
You
cannot open the oven door even though no process is running.
10.4.1
The
oven is not fully purged. Run the vent program by setting the thumbwheel to 2
and press START.
Note: Be careful when oven temperature is high. You can burn yourself.
10.5
Your
process was aborted with an alarm while you were away and you want to know how
far it went.
10.5.1
On the
touch screen, press the Alarms Panel button. The alarms panel
will display a list of all alarms and the times at which they occurred. If you noted when your process began, then
the alarms panel will tell you when it aborted with an alarm.
11.0
Figures & Schematics
Vacoven Controllers Controllers
Main Power Switch
Main Vacuum & House Vacuum Hot
and Cold N2 Flow Control Valves
12.0
Appendices
12.1
How
To View a Program Without Running It
12.1.1
Select
the desired program number on the Partlow by pressing PROF button.
12.1.2
Press MODE
button.
12.1.3
Press RUN/HOLD
button to index through the segments.
12.1.4
Press SCROLL
(the circular arrow) button to see the temperature, time, and event output of
each segment.
12.2
How
To Program the Partlow Controller
The
partlow can store eight different temperature programs. Any given program can
be joined to another program or repeated. For example, Program 1 can run
Program 2 three times and then run Program 5 and then ramp up to 400°C, and
dwell there for 2 hours, and end up by returning to the standby temperature.
Each
program is divided into segments. There is a maximum of 16 segments in a
program. A segment is composed if three specifications: a temperature, a time
and an event output. Each segment tells the oven how to proceed from its
previous state. The temperature (Final
SP on the Partlow message display) may be a number between 0 and 450°C, but
realize that the oven has no way of cooling below room temperature. The
temperature can also be a dwell, denoted ---- on the Partlow. A dwell means to
stay at the current temperature and it can be selected by pressing the up and
down arrows at the same time. It is recommended that all programs have a
5-minute dwell at the standby temperature to accommodate the time it takes for
the dehydration loops (3 dehydration loops = ~ 4 minutes) for the first
segment. The Time specification indicates how long to attain this
temperature step. The Partlow is currently set to display time as hh.mm format,
hours and minutes. By scrolling below 00.00 minutes, you will also be able to
select End program and various join options. (For example, J03 inserts Program
3 as the current segment..) All
programs must end with an End segment. If you select the End specification, the
Final SP and Event outputs for the current segments are automatically set to
End as well. The Event output specification is a 4-digit binary number
and should be set to 0 for all segments except for the last segment. The
segment before the one specifying the End must be set to 0001. This tells the
Partlow to signal to the oven that the program is over and vacuum may now be
purged, etc..
Note: Programs can only be entered
when the Partlow is in Program Define Mode.
12.2.1
On the
Partlow, press PROF button to select the number of the program you want
to edit. Currently, Programs 1 to 5 are predefined programs. (Ask a process
engineer which programs are available for editing: Programs 6 to 8 are
currently available.)
12.2.2
Now
press SCROLL (circular arrow) and UP ARROW buttons at the same
time.
12.2.3
Next,
use the UP ARROW key to select the unlock code number, which is 10.
12.2.4
Press SCROLL
button. Now you are in the Program Define Mode and you can proceed to define
the segments of your program.
12.2.5
To
exit the Program Define Mode when finish programming, press the MODE
button until the Partlow message display prompts Exit?
12.2.6
Then
press SCROLL button.
Note: When specifying a temperature
cool down segment, be aware that the YES oven only can cool down at a maximum
rate of about three degrees per minute for temperatures above 200°C and less
than 2 degrees per minute for temperatures under 200°C. If you want the oven to cool as fast as
possible, specify 0°C as the temperature in the temperature ramp down segment.
12.3
Quasi-Manual
Mode
It is
possible to approximate manual operation of the YES oven by changing the
standby temperature to your desired process temperature.
12.3.1
To change
the standby temperature, press SCROLL until the message display prompts Ctr
SP t.
12.3.2
Then
press the UP/DOWN arrow to change the standby temperature.
12.3.3
After
you have reset the temperature, press SCROLL until the message display
is blank to exit. Be sure to
change the standby temperature back to its original value when you are done!
12.4
Program
#1 - Standard 450°C Anneal Program
Let’s
assume the idle temperature is set to 75°C.
|
Program Box |
Segment Box |
Message Display |
Upper Display |
Lower Display |
|
1 |
1 |
Final SP |
Current Temp |
300
RAMP (ramp up) |
|
1 |
1 |
Time |
Current Temp |
1.00
RAMP (1 hour) |
|
1 |
1 |
Event |
Current Temp |
0000
Event Output |
|
1 |
2 |
Final SP |
Current Temp |
----
DWELL |
|
1 |
2 |
Time |
Current Temp |
0.30
DWELL |
|
1 |
2 |
Event |
Current Temp |
0000
Event Output |
|
1 |
3 |
Final SP |
Current Temp |
450
RAMP (ramp up) |
|
1 |
3 |
Time |
Current Temp |
1.00
RAMP |
|
1 |
3 |
Event |
Current Temp |
0000
Event Output |
|
1 |
4 |
Final SP |
Current Temp |
----
DWELL |
|
1 |
4 |
Time |
Current Temp |
0.30
DWELL |
|
1 |
4 |
Event |
Current Temp |
0000
Event Output |
|
1 |
5 |
Final SP |
Current Temp |
75
RAMP (ramp down) |
|
1 |
5 |
Time |
Current Temp |
4.00
RAMP (4 hours) |
|
1 |
5 |
Event |
Current Temp |
0001
Event Output #1 On |
|
1 |
6 |
Final SP |
Current Temp |
----
DWELL |
|
1 |
6 |
Time |
Current Temp |
0.01
DWELL |
|
1 |
6 |
Event |
Current Temp |
0001
Event Output #1 Off |
|
1 |
7 |
Final SP |
Current Temp |
END
End of Program |
|
1 |
7 |
Time |
Current Temp |
END End
of Program |
|
1 |
7 |
Event |
Current Temp |
END
End of Program |