suss microtec ma6 mask aligner standard operating procedure

SUSS MICROTEC MA6 MASK ALIGNER
STANDARD OPERATING PROCEDURE
Purpose of this Instrument: This machine is for patterning photosensitive polymers with UV
light.
Location: Engineering Sciences Building (ESB) Room G75C2 Cleanroom
Primary Staff Contact: Dr. Kolin Brown
(304) 366-6551
Office: ESB G75D
Secondary Staff Contact: Harley Hart
(412)443-1514
Office: WH 409
[email protected]
[email protected]
The Shared Research Facilities are operated for the benefit of all researchers. If you encounter
any problems with this piece of equipment, please contact the staff member listed above
immediately. There is never a penalty for asking questions. If the equipment is not behaving
exactly the way it should, contact a staff member.
WARNING: The mask aligner emits UV light. Exposure of UV light on unprotected skin can
cause severe burns. Looking directly into the UV light source can cause temporary or
permanent blindness.
WARNING: If at any time during operation, there is a sound of shattering glass and the voltage
led display on the lamp power supply drops to zero or displays “fail” turn off the lamp
controller and mask aligner, evacuate all users from the room, and notify a Shared Facilities
staff member. Do not attempt to open the system or inspect the arc lamp! Mercury vapor
may be released if the arc lamp breaks. Opening the lamp housing will expose you to this
vapor.
ATTENTION: Users are required to wear UV protective glasses when operating the mask
aligner. These glasses are located on top of the mask aligner. Additional UV protective glasses
may be found next to the flood exposure system in the same room.
UV LAMP START UP
1. Sign onto the FOM and sign into the logbook.
2. Make sure the Mask Aligner is turned off. Power up the lamp controller by turning on the power
switch on the right hand side of the panel. A picture of the lamp controller is shown in Figure 1,
and it is located under the Mask Aligner table. Once turned on, the lamp controller led panel will
cycle through a warm up procedure. When finished warming up, the led display will state “rdy”
for ready.
NOTE: The lamp power supply is interlocked with the Mask Aligner. The lamp cannot ignite if the
Mask Aligner is on.
Figure 1: Lamp Controller in idle state.
3. Start the arc lamp by pressing, and holding for a few seconds, the start button. If the arc lamp
ignites successfully, the led display on the lamp power supply will show “cold”. If the lamp does
not ignite immediately, it will attempt ignition five times. If the lamp controller does not display
the “cold” message but displays “fail” or continues to display “rdy”, then try again. If the lamp
does not ignite after the third attempt, please contact a Shared Facilities staff member for
assistance.
4. Wait 15 minutes for the lamp to warm up. The led display on the lamp power supply should read
275 Watts.
WARNING: If the power does not read 275 W do not proceed. Attempting to run the lamp at a
higher idle power may cause the lamp to fail or crack. Contact a Shared Facilities Staff member for
assistance.
STARTING UP THE MASK ALIGNER
1. Power on the Mask Aligner by turning the power switch to the “ON” position. Once turned on
the machine will initialize. The LCD display will display the current warm up step.
2. If the machine gives a “chuck out of range” message and there is an audible alarm, then the
chuck is out of center and the system cannot proceed with startup. To center the chuck:

Check the error message. The machine will give the status of X, Y, and T. One or all of these
parameters will show out of range and state the direction to move the stage.

For any parameter out of range, use the appropriate micrometer (shown in Figure 2), and
move the chuck back to center. The X micrometer should read ~10 and the Y micrometer
should read ~10 when the stage is centered. The T rotational indicator, located on the
front of the alignment stage, should be centered as shown in Figure 3. The T micrometer
can be adjusted to center the rotational indicator.
Y position micrometer
T position micrometer X position micrometer
Figure 2: Aligner chuck and positioning micrometers.
Figure 3: Chuck rotational indicator in the centered position.
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When the chuck is centered the audible alarm will stop and the error message will state
“Chuck is in center position proceed with enter.”

Press the enter button to proceed with the aligner initialization.
WARNING: If there is any alarm other than chuck out of center, contact a Shared Facility staff
member immediately. Other alarms may indicate low pressure, or microscope out of range.
Continued operation of the machine without corrective action by a staff member may cause
damage to your substrate, photo mask and/or the aligner.
3. The LCD screen will prompt you to press the load button. The load button should be the flashing
green button on the front panel. Press it to continue the machine initialization.
4. After initialization the LCD display should display a standard operating screen as shown in Figure
4.
Figure 4: Standard operating screen.
MEASURING THE UV INTENISTY
1. The output UV intensity should be measured and recorded in the log book when the lamp has
been turned on. Make sure that the lamp has warmed up before taking the UV measurement
by waiting 15 minutes.
2. Turn on the UV meter, and measure the output UV intensity with the Karl Suss 1000 UV intensity
meter and probe, shown in Figure 5. The probe should have a label on the side marking it as a
320nm probe. There are two probes in the cleanroom. If the probe is labeled 365nm, then you
have the one associated with the UV flood exposure. It cannot be used with the mask aligner.
Place the correct probe on the center of the substrate chuck with the silver disc up.
3. Press the “LAMP TEST” button on the mask aligner control panel. The microscope will
automatically move to the up position, and the mirror housing will automatically move forward
as the UV light shutter opens.
4. Record the UV meter value and record it in the logbook. Units are in mW/cm2.
5. Press the “LAMP TEST” button again to stop the process.
6. This process should be repeated with the photomask placed over the 320nm UV probe for
experimental calculations.
NOTE: Make sure that the silver disc is not covered by any darkened area of the mask. If any
part of the mask covers the silver disc area, then the measured value will be lower than the
actual UV intensity.
Figure 5: Karl Suss UV intensity Meter Model 1000 with Probe
SELECTING A CONTACT MODE AND SETTING PROCESS PARAMETERS
1.
Users must use the “select program” button to select a proper contact mode before operating
the machine. Each press of the button will cycle through the five different contact modes.
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Hard Contact- This mode is for working with full 2”, 3” or 4” wafers. When working in
hard contact mode, the mask opening and wafer chuck must match the wafer diameter.
A high contact pressure will be applied to press the sample against the mask to minimize
any gaps between the wafer and the mask.
Soft Contact- This mode is for working with samples that are smaller than the mask
opening. A lower contact pressure will be applied to press the sample against the mask
to minimize gaps. A softer contact pressure is required for smaller samples, because the
contact area is reduced and the pressure will be focused on a smaller region of the
mask.
Vacuum- this mode is for working with full 3” or 4” wafers only. When working in
vacuum contact mode, the mask opening and the wafer chuck must match the wafer
diameter. The 3” and 4” chucks have an inflatable, orange seal which can create a seal
between the wafer and the mask. A vacuum can then be applied to remove any air
between the wafer and the mask to eliminate gaps.
Low Vacuum- Like vacuum contact, this mode is for working with full 3” or 4” wafers
only. When working in vacuum contact mode, the mask opening and the wafer chuck

must match the wafer diameter. The 3” and 4” chucks have an inflatable, orange seal
which can create a seal between the wafer and the mask, and a vacuum can then be
applied to remove any air between the wafer and mask, and an additional contact force
will be applied to the wafer to eliminate gaps.
Proximity- This mode is for working with extremely delicate samples that will break if
put under contact pressure. The sample will not touch the mask in proximity mode.
Please contact a Share Research Facility staff member if using proximity mode, because
additional parameters must be set before loading the sample.
NOTE: Using Hard Contact Mode with partial wafers or small samples may result in damage to
the sample or cause the mask to crack.
2.
Calculate the exposure time by dividing the desired exposure dosage, which should be in
mJ/cm2 by the through mask UV intensity measured in mW/cm2.
NOTE: Make sure to record both the measured intensity and calculated time in your lab
notebook. The measured intensity will change over time, resulting in a change in exposure time.
3. Press the “Edit Parameter” button to open the parameter menu. The first parameter should be
exposure time. Adjust the exposure time shown to your calculated exposure time using the up
and down arrow keys on the mask aligner control panel. These buttons will increase or
decrease the time in 0.1 s steps. Pressing the “FAST” buttons while using the up and down
arrows will increase or decrease the time in 10 s steps.
4. Press the right arrow button to scroll through the parameters. Check the alignment gap
settings. The gap value can be changed using the up and down arrow keys. A larger alignment
gap is required for thicker substrates. The alignment gap can be decreased if working with a
higher microscope magnification due to the decreased depth of focus. A default gap of 100
microns is recommended for most processes.
WARNING: Do not adjust the WEC Type: Contact parameter. The WEC controls the auto
leveling feature of the mask aligner. Turning off or changing the WEC Type parameter may
result in the damage of the sample, mask or mask aligner when operating in contact mode.
5. Press the “Edit Parameter” button to save all changes.
LOADING A MASK
There are three mask holders for the MA6 Aligner: a holder with a 2” diameter opening, a holder with a
3” diameter opening and a holder with a 4” diameter holding. The mask holder opening should be the
same size as the wafer. If the user is using a partial wafer, then the mask holder should be the opening
that best fits the partial wafer.
WARNING: The wafer or partial wafer should never be larger than the mask aligner opening. Trying to
use a smaller mask opening can result in damage to the sample or mask aligner.
1.
If the mask holder needs to be changed, disconnect it from the mask aligner by grabbing the
knurled collar and push it towards the mask aligner as shown in Figure 6.
2. Connect the chosen mask holder by inserting the vacuum tube connector into the knurled nut.
The connector should click into place.
3. Mount the mask on the mask holder as shown in Figure 7. The mask should be positioned so
that the chrome side of the mask is facing up. The mask should be aligned to the two posts (or
three depending on the holder) and be flush with the black bumper.
Figure 6: Releasing the mask holder vacuum connection tube from the mask aligner.
Black bumper
Alignment posts
Mask clamp
Press down here to release clamp
Figure 7: A photo mask mounted on the mask holder.
4. Release the mask clamp by pressing firmly in a downward direction on the clamp release shown
in Figure 7. The pressure must be applied in a vertical direction. The clamp will not release if any
pressure is applied in the lateral direction.
5. On the mask aligner press the “Change Mask” button. The process screen will give a message
stating that the mask may now be changed and to press enter to toggle the vacuum. Then it will
state “Vacuum: Off”.
6. Press the “Enter” button on the keypad to turn on the vacuum to the mask holder. Once the
display messages changes to “Vacuum: On”, the mask should be securely attached to the mask
holder.
7. Pick up the mask holder, and flip it. Insert the mask holder into the mask holder grooves on the
mask aligner, as shown in Figure 8. Fully insert the mask holder, and make sure that the holder
is flush with the mask aligner.
Figure 8: Insert the mask holder into the aligner.
8. Press the “Change Mask” button on the aligner keypad and the display screen will change back
to the standard operation screen. Check to ensure that the mask holder is locked in place. If
the mask holder can be moved, press the “Change Mask” button and reinsert the holder.
INSTALLING THE SUBSTRATE CHUCK
The substrate chuck should be the same size as the mask holder opening regardless of the size of the
sample.
WARNING: Using a substrate chuck that is smaller than the mask holder opening may result in damage
to the mask. Repeated use of mismatched mask holder and chuck will cause the machine sensors to
loose Z position. Once the sensor loses Z position, the machine must be restored to factory settings to
recalibrate the Z position sensor. Failure to reset the sensor may result in damage to other user’s
substrates or masks.
1. To change the substrate chuck, pull the slide out to the fully extended position. The slide will
lock open.
2. Placing one hand under the chuck, carefully lift the chuck plate up. Use the other hand to grab
the chuck plate and remove it from the machine.
WARNING: Be careful when removing and replacing the wafer chuck plate. Twisting the plate
or rough handling may damage the vacuum gasket on the side.
3. Select the proper chuck plate and gently lower it onto the slide. The line on the chuck plate
should line up with the position pin on the slide. This is shown in Figure 9.
Figure 9: Chuck plate alignment.
4. Gently push the slide back into the aligner.
LOADING A WAFER
1. Press the “Load” button on the mask aligner to load the wafer, and follow the instructions on
the screen. The process can be aborted at any time by pressing the “Unload” button on the
aligner.
2. When prompted by the machine, gently pull the slide out to the fully extended position. The
slide will lock open. Load the substrate onto the wafer chuck. For best results partial substrates
should be placed in the center of the chuck. Once the substrate is in position, press “Enter and
a vacuum will be pulled on the chuck to hold the substrate in place.
NOTE: The 2” wafer chuck is designed for holding substrates that are 2” in diameter or smaller.
As shown in Figure 10, the 2” chuck is a clear quartz disk with two sets of vacuum grooves milled
into its top surface. The small X in the center of the chuck is vacuum channel I and the other
grooves are vacuum channel II. The user has the ability to apply vacuum to these channels
separately. Figure 11 is a close-up of the vacuum selector panel that is located on the two inch
wafer chuck. Using a small screwdriver the users can select the vacuum settings for vacuum
channel I and II. Channel I should be turned on and channel II should be turned off when using
substrates that are smaller than 2” in diameter. Channel II should be turned on when using 2”
diameter substrates.
Figure 10: The two inch wafer chuck vacuum grooves.
Figure 11: The two inch wafer chuck vacuum channel selection panel.
3. The machine will instruct you to push in the slide and press “Enter”. When prompted by enter,
the mask aligner will raise the wafer to the mask and preform the Wedge Error Correct (WEC)
procedure. This procedure levels the wafer to the mask and then adjusts the Z measurement to
the alignment gap.
If the wafer does not completely cover the grooves on the wafer chuck, then the machine will
lose vacuum during the WEC procedure. The machine will notify the user of the loss and prompt
the user to ignore with Enter: to continue the process without vacuum, press “Enter”, or to
abort the process, press “Unload”.
NOTE: There should be no loss of vacuum when using two, three or four inch wafers. A loss of
vacuum warning for a full wafer is usually caused by debris on the substrate backside. The user
can choose to abort the process and clean the backside of the wafer or continue the process.
4. Once the wafer is loaded, the user can align the wafer to the mask or abort the process by
pressing “Unload” to remove the wafer from the mask aligner.
ALIGNING A WAFER TO THE MASK
1. The mask aligner will automatically lower the microscope assembly when the wafer is loaded.
2. If using a partial substrate or a mask with multiple patterns, the microscope assembly can be
moved into the up position by pressing the “F1” button on the aligner keypad and then pressing
the “Enter” key. With the microscope assembly out of the way, the user can visually inspect the
substrate position in relationship to the mask before trying to make fine position adjustments.
The user may need to unload the substrate and reposition it on the wafer chuck.
3. The microscope assembly is used for inspecting the substrate position in relationship to the
mask. There are two microscope columns on the microscope assembly, right and left. Each
microscope column has three sets of objectives. The user may choose between 5x, 10x, and 20x
magnification.
The output of the microscope columns may be viewed on the video monitor on top of the mask
aligner. The microscope output selector switch (shown in Figure 12) allows the user to select
which microscope column is displayed on the screen. The knob should be turned to the desired
selection:
o LEFT- displays the video output of the left microscope column objective
o SPLITFIELD- splits the video screen in half, and each half displays the video output from
the left and right microscope column objectives. Due to the spacing between the two
columns this function is only useful when using the four inch opening mask holder.
o RIGHT- displays the video output of the right microscope column objective
A focus knob is located on the top of the microscope assembly as shown in Figure 13. The knob
should be used to bring the video image into focus. The higher magnification objectives have a
shorter working distance. If the alignment gap is large, the mask pattern and the substrate
pattern may be brought into focus together. The user must unload the wafer and reset the
alignment gap parameter to a smaller gap.
4. The microscope assembly can be positioned using the four directional arrows on the mask
aligner keypad. Pressing the “Fast” button will speed up the microscope movement. For best
alignment, the users should visually inspect several locations on the pattern when aligning the
substrate to the mask.
Figure 12: Microscope output selector switch, located on the front panel of the mask aligner.
Focus knob
Figure 13: Focus knob on the top of the microscope assembly.
5. Using the X position, Y position and T position micrometers adjust the position of the substrate
features to line up with the mask patterns. For best results, use the T position micrometer to
align the substrate rotation first, before adjusting the X and Y positions.
EXPOSING THE SUBSTRATE
1. Once the substrate is properly aligned to the mask, the user must press the “Align/Contact”
button to bring the substrate into contact with the mask. When the substrate is in contact, the
yellow contact button on the front of the mask aligner panel shown in Figure14 will light.
Figure 14: The Contact Light is unlit when the substrate is in alignment position.
2. If performing critical alignment of substrate features to the mask, the user should re-inspect the
substrate and mask position to ensure that the substrate did not move while being brought into
contact with the mask.
To make adjustments to the substrate positions, press the “Align/Contact” button again; and the
wafer chuck will lower the wafer to the alignment position and turn off the contact light.
WARNING: Do not try to adjust the substrate position while in contact with the mask! This will
damage the photoresist on the substrate and may damage the mask.
3. To expose the substrate, make sure the contact light is lit and then press the “Exposure” button.
The machine will automatically lift the microscope unit, slide forward the exposure mirror and
open the shutter for the exposure time. Once the shutter is closed the machine will
automatically lower the wafer chuck and prompt the user to pull out the slide and remove the
substrate. Make sure that the slide is pulled out to the fully extended position to turn off the
vacuum.
4. Remove the substrate and push the slide back into the mask aligner.
TURNING OFF THE SYSTEM
1. Before shutting down the system, the user must first remove their mask from the aligner. To
remove the mask, press the “Change mask” button. The machine will lift the microscope
assembly to the up position and unlock the wafer holder. The user may then remove the wafer
holder from the mask aligner and place it upside down on the mask holder rest that is to the left
of the machine.
2. Press the “Enter” button to turn off the vacuum to the mask holder. Release the mask clamp by
pulling the clamp away from the mask using the indentation in the black clamp bar. The mask
clamp will lock in the open position.
3. The user may now remove the mask from the mask holder.
4. Center the aligner stage by setting the X micrometer to ~5 and the Y micrometer to ~10. The T
micrometer can be adjusted to center the rotational indicator.
5. Power off the Mask Aligner by turning the power switch to the “OFF” position.
6. Power off the lamp controller by turning off the power switch.
7. Clean up the work area and make sure that the log book was properly filled out with all
requested parameters.
8. Sign out of the FOM.
EMERGENCY PROCEDURES
If no one is available and the machine is not acting as expected, the user should do the following:



Turn OFF the system power
Turn OFF the lamp power
Send an email through the FOM by selecting PROBLEM REPORT and entering details of the issue
in the COMMENTS section
Do not leave the machine running in an abnormal state. If the machine cannot be placed in STANDBY
MODE, immediately contact:
Primary Staff Contact: Dr. Kolin Brown
Secondary Staff Contact:
(304) 366-6551
Office: ESB G75D
[email protected]
Harley Hart
(412)443-1514
Office: WH 409
[email protected]
If it becomes necessary to leave the instrument then the user should leave a large, legible note on the
Mask Aligner Tool stating the tool is DOWN. The user should also add a comment as to tool status when
logging out of the FOM software.
If a dangerous situation is evident (smoke, fire, sparks, etc.), the user should turn off the system and
lamp controller or unplug the tool, ONLY if it is safe to do so. The user should notify all other
cleanroom persons within the cleanroom to evacuate and leave the clean room immediately. The user
should then contact proper emergency personnel from a safe place. The contact numbers can also be
found posted outside of the clean room.