Chapter 4.15
(quintel)
1.0
Title
Quintel Q4000 Mask Aligner
2.0
Purpose
The Quintel Q4000 MA (Mask Aligner) is a top and bottom side
contact lithography printer with the video-view split field microscope used for
fine line lithography down to 1 micron or better. It is capable of processing
both 4- and 6-inch substrates. After reading this manual, the user should be
able to describe a typical MA (quintel) process for both top and backside
alignment; explain the theory of operation; and state all hazards associated
with the system. After successfully completing the qualification procedures for
this tool (see Appendix), the user should be able to perform a full
photolithography process for both TSA and BSA using this system. Only trained
and approved (qualified) Users may use this tool.
3.0
Scope
The mask aligner consists of several coordinated,
inter-related systems including:
3.1
Substrate loading, holding and
unloading system.
3.2
The mask supporting system.
3.3
The substrate/mask/scan/align/lock
system.
3.4
The viewing system (microscope and
illuminators).
3.5
The exposing system.
3.6
Use 5-inch to 7-inch masks. Select
the appropriate mask holders for 5 or 7 mask. Contact staff for changing to
7-inch mask holder.
4.0
Applicable
Documents
Quintel Q4000 Operating Manual: Manufacturer
hardcopy is located in the Microlab office.
5.0
Definitions
& Process Terminology
All the front panel controls are push-on, push-off buttons
with indicator lamps. The buttons are illuminated green when an option is
active.
5.1
MASK VACUUM Turns
vacuum on/off to affix mask to mask chuck.
5.2
MASK CLAMP Turns
vacuum on/off, enabling the mask clamp to stick to the mask from above. (The
clamp is a frame that is a secondary means of attachment.)
5.3
LOAD/CLEAR Raises
the wafer chuck.
5.4
CLEAR Lowers the
wafer chuck.
5.5
SEP/CONTACT When a
wafer is loaded, the chuck will planarize with the mask and then lower out of
contact for alignment. Contact is selected to put the wafer back into contact
with the mask, after alignment and before exposing. Lights illuminate to
indicate which mode is active.
5.6
EXPOSE Exposes
the wafer to UV light when activated.
5.7
Focus UP/DOWN button Changes
the microscope level in order to focus on the sample.
5.8
Red Indicating Pointer Attached
to the front of the wafer chuck assembly, indicates the theta position (chuck
rotation). Starting it centered, gives you maximum theta adjustment.
5.9
SEPARATION PRESSURE Used to
establish the separation distance for alignment. Preset by staff.
5.10
CHAMBER VACUUM Used in
setting up the machine for vacuum printing. Preset by staff.
5.11
ILLUMINATION Top and
bottom light sources for alignment. Select the appropriate knob position for
the top and IR light source. There are also four knobs that control
illumination levels for the microscope and IR source. They all should be in off
position when the machine is not in use.
6.0
Safety
6.1
Ultra Violet Light - The Quintel
uses broadband ultraviolet light (UV) to expose photoresist. Direct exposure to
UV light can damage the cornea of the eyes and also cause sunburn. In normal
use the Quintel does not represent a hazard; however, if the lamp cover is
removed or if an exposure is made using the shutter override switch, UV injury
could result.
6.2
High Voltage - Mercury
arc lamps require high voltage to start and operate at potentially lethal dc
voltage. DO NOT TAMPER WITH THE ARC LAMP SYSTEM OR ARC LAMP SUPPLY. If
the lamp is off, do not turn it on. Report as equipment problem on the WAND
using FAULTS.
7.0
Statistical
Process/Data
N/A
8.0
Available
Processes, Process Notes
8.1
The correct default idle state of
the Q4000 should be as follows:
8.1.1
System power ON and HEAD
8.1.2
2105C2 Illumination Controller:
8.1.3
Monitor is OFF.
8.1.4
MV-200 power box is OFF. H/V split
knob marker set at center. H/V switch set at V. All A & B cross hair
switches set at OFF.
8.1.5
The 5-inch dummy mask is loaded
without mask vacuum and the 4-inch MA lithography chuck is in the down
position. No wafer is on the chuck.
8.1.6
Microscope Magnification range is
10X to 70X.
8.1.7
Normally, the vacuum on the wafer
chuck switches on automatically when the wafer chuck assembly is in. Otherwise,
it switches off when it is out.
8.1.8
Maximum substrate thickness for
standard operation is 5.08 mm or .2 inch.
8.1.9
Separation Gap Preset by staff.
Recommend 30 ΅m or .0016 with 2X objective power. Maximum gap can be 100 ΅m or
.004. Recommend 20 ΅m or .0008 with 5X objective power. Maximum gap can be 50
΅m or .002.
8.2 Basic Exposure Programs
8.2.1
CONTACT CALIB Used to
select proximity printing mode. Contact staff to set it up.
8.2.2
PRESSURE CONTACT Selects pressure
contact mode, the normal operation mode.
8.2.3
VACUUM CONTACT Mode
that applies vacuum between the mask and the wafer, used for highest resolution
possible. A 0-30 vacuum gauge indicator is located on the left hand side of
the tool.
8.3
Exposing Small Dice
The vacuum chuck is designed for 100 mm (4") wafers. If
you use odd sized substrate, there are several methods for adapting the 100 mm
wafer chuck. You can cut a 100 mm diameter piece of Mylar film and make a
cutout for your sample. You can mount your sample to a wafer with wax or mount
your sample to wafer dicing tape. Whatever method, the
goal is to obtain good chuck vacuum. Planarization may be adversely affected by
having a sample off center. It may be necessary to place another sample
opposite it for balance.
9.0
Equipment
Operation
9.1
Enable the quintel on the wand.
9.2
All selection controls should be
unlit except the POWER and HEAD LOCK.
9.3
Check if the lamp is on by the
seeing if there are power and voltage readings on the lamp power supply.
9.4
Set the Exposure Time On the
UniOp Programmable Logic Controller (PLC)
9.4.1
Select 1 from the main menu for
Exp Time.
9.4.2
Press Insert, and the
cursor will blink.
9.4.3
Enter the desired time, up to 999
seconds. Contact the Process Engineering Manager if you need a longer exposure.
9.4.4
Press Enter to return to
the main menu.
9.5
Set the Exposure Mode On the
UniOp Programmable Logic Controller
9.5.1
Select 2 from the main menu for Pr
Modes.
9.5.2
Enter # to select desired mode, an
asterisk will appear besides the process mode selected.
9.5.3
Press Enter to return to
the main menu.
9.6
Set the Operation Mode On the
UniOp PLC
9.6.1
Select 3 from the main menu for Op
Modes.
9.6.1.1
Enter 1 for Exp Pressure.
9.6.1.1.1
Use in pressure contact mode for
highest resolution.
9.6.1.2
Enter 2 for Contact Expose
Pressure.
9.6.1.2.1
Normal contact exposure mode.
9.6.1.3
Enter 3 for IR View.
9.6.1.3.1
Activates IR viewing illumination.
9.6.1.3.2
Activates controls to move/remove
IR illumination system after a wafer is loaded/unloaded.
9.6.2
Press Enter to return to
the main menu.
9.7 Loading the Mask
9.7.1
Lift off the mask clamp, remove dummy
mask, and place your mask on the mask vacuum chuck with the emulsion or chrome
side facing down. The mask should rest against the banking pins in the rear
left corner. Center the mask clamp plate over the mask and press the MASK CLAMP
button to enable the vacuum and fix the mask clamp to the mask. The MASK CLAMP
light will go on indicating vacuum. Center mask and mask plate over the opening
and press MASK VACUUM to fix assembly to the mask vacuum chuck. When the light
is on vacuum is present to hold the mask.
9.8 Rotational Alignment of the Mask to the
Microscope
9.8.1
Select MIC on the illumination
selection switch if not using the IR feature. Turn up the light intensity for
the L&R microscope illuminators. Turn on the ULT9.RAK monitor and MV-200
box. Adjust the focus on both objectives simultaneously with the black toggle
switch on the front left control panel of the tool scan, using the left hand
disc to locate the alignment marks. You will want to start with the microscope
on the lowest magnification setting (align 1 to the marks under the zoom labels
on the objectives). One alignment mark should be visible on each half of the
split field image. To get both into the field of view you may need to adjust
the spacing between the split-field objectives, and/or the rotation of the
mask.
9.8.1.1
Using IR feature for backside
alignment
9.8.1.1.1 Select IR/OPTL ILLUM on the illumination selection switch. Turn
up the IR illuminators. This will allow you to see the mask and the backside of
the wafer when loaded. You can also select BOTH on the illumination selection
switch, but the microscope illuminators cannot be too bright otherwise it will
wash out the IR image and you will not be able to see it. Also, the microscope
objectives must be over the IR illuminators in order to see both the backside
and mask features. In other words, you cannot illuminate one place and look for
the image elsewhere.
9.8.2
Use the large knobs at the
left-hand side and right-hand side of the microscope to adjust the spacing
between the split-field objectives, making sure they are unlocked before
adjusting. Four small knobs on the microscope bracket are for tightening the X
and Y microscope movement. Make sure these 4 small knobs are loose before
making the adjustment, because otherwise you will strip the threads on the
rails, which is a very expensive damage. Looking from side at the top of the
mask with your naked eye can be helpful for finding the right spacing. The
green light of the microscope illuminator can be seen on the mask, indicating
where the objectives are aimed.
9.8.3
Mask Rotation
9.8.3.1
Press the MASK VACUUM
switch to turn off the vacuum, releasing the mask. The MASK
VACUUM switch will be unlit.
9.8.3.2
Rotate the mask clamp (with the
mask) while holding it against the rear left banking pins, until the alignment marks
are roughly centered in the two fields as seen on the ULTRAK monitor.
9.8.3.3
Press the MASK VACUUM
switch again to fix the assembly to the mask vacuum chuck.
9.9 Loading and Aligning the Wafer
9.9.1
Slide the wafer chuck assembly towards you until it stops. With
tweezers, center your wafer on the chuck. Align flat against the white plastic
flat-finder. Push the wafer chuck assembly 1 or 2 inches and listen to the
click, which is the chuck vacuum turning on. Return the plastic flat-finder to
its original position push the assembly fully back under the mask until it hits
its stop.
9.9.2
Press the LOAD switch and the wafer will be raised
under the mask and held in place. The wafer will contact the mask to planarize
the wafer to the mask; a then the SEPARATE button should light,
indicating that there is a separation between the wafer and the mask. The
instrument goes into separation mode automatically.
Note: Lab members have many
different size substrates that are aligned to masks using the quintel tool. The
force that the chuck exerts when the substrate contacts the mask varies with
the size of the wafer. Optimal condition is selected by the user.
There is a gage and regulator on the left hand side of the
machine. This adjustment must be done prior to loading the wafer. Decreasing
the pounds per square inch (psi) will soften the contact force. Increasing the
psi will increase the contact force. Factory setting of the contact force is 15
psi.
9.9.3
Confirm you are in the SEPARATION mode and proceed to align your substrate or wafer.
9.9.4
Align your wafer using split field
as mask alignments on the mask should be visible after the Step 9.9.1
procedure. There are two degrees of motion reduction available or the align
stage. It either operates at a 3:1 ratio coarse align mode or at a 150:1 ratio
fine align mode. Use the right hand joystick on the align stage to
search for the alignment marks on the wafer to match the alignment marks on the
mask. Press the COARSE button on the left front panel and the right hand
side joystick simultaneously to make coarse alignment. Next, use the theta
micrometer on the left side of the stage to rotate the alignment marks on wafer
to match the mask alignment marks. Press the button on the scan-align stage
joystick on the left front side to move the alignment marks into the viewing
position under both objectives. The scan-align mode moves the stage and
the mask together.
9.9.5
When alignment is complete,
pressing the CONTACT button will bring the wafer into contact with the mask.
Confirm the alignment is correct. If an adjustment is necessary, press the SEPARATE
button and realign.
9.10 Procedure for Backside Alignment
Alignment marks must be within the IR viewing windows on the
wafer chuck. The position of the light pipes may be changed by adjusting the thumbscrews
on the light pipe insertion assembly. The default objective separation of 51.15
mm (2.25) is set for current 4 wafer chuck. The infrared light pipes work by
projecting infrared light up from the wafer chuck, through the wafer. Features
on the backside of the wafer cast shadows up to the focal plane, located at
mask level. To generate an IR image, these light pipes must be positioned below
the split-field microscope objectives. If the pipes are grossly out of
alignment, no image will be seen. If the pipes are slightly out of alignment,
shadows will be cast up at angles, thereby affecting alignment. Adjust each
pipe grossly so that it illuminates respective to the target. Perform a fine
pipe alignment by watching the motion of backside features as you adjust the
pipes. It is usually possible to determine when the pipe is directly below the
target by watching the rate at which the shadow moves as you move the pipe. The
motion of the backside image should be at a minimum when the pipe is directly below
its target. Follow the same procedure as Steps 9.6 to 9.9.
9.11 Expose the Wafer Press EXPOSE button. The
Expose position provides a reflector to direct the UV light down to the
wafer.
9.11.1 After exposure, the chuck lowers automatically. Pull the wafer chuck
assembly out all the way towards you. Remove the wafer with tweezers, and then
push the wafer chuck assembly back in.
9.12 Removing the Mask
9.12.1 To
remove the mask, press the MASK VACUUM button (light will go off)
to release the mask from the mask vacuum chuck. You can now lift the mask out
using the mask clamp. Place the mask right side up on top of the left cover on
the Quintel aligner. Press the MASK CLAMP button (light will go
off) to release the mask. Make sure you put the mask clamp with vacuum hole
side up, on top of the left control panel.
9.13 System Shutdown
9.13.1 Illumination
selection switch should be off.
9.13.1.1
All four light control knobs fully
counterclockwise.
9.13.1.2
IR View should be off on the Op
Modes.
9.13.2 Wafer chuck down.
9.13.3 Ensure the substrate chuck is pushed entirely in.
9.13.4 Mask Vacuum off.
9.13.5 Power off on Ultrak monitor and MV-200.
9.13.6 Do not turn off main POWER, HEAD LOCK or UniOp.
9.14 Measure Lamp Intensity
9.14.1
The exposure power is
approximately 8.3 to 15.0 14.2 mW/cm2 for
I-line.
9.14.2
Obtain Karl Suss UV Intensity
Meter Model 1000 from the drawer next to the Karl Suss Aligner.
9.14.3
Select 4 from the main menu for
Controls Mode on the OniOp PLC.
9.14.4
Enter 3 for Expose Test on the
menu. The optical head will rise.
9.14.5
Connect the I-line probe to the UV
intensity meter. Turn on the power on the intensity meter. Put the I-line probe
in its holder and place it on the center of the dummy mask from the side of the
tool.
9.14.6
Enter 2 for Manual Shutter on the
menu.
9.14.7
You can read the intensity on the
meter.
9.14.8
Press 2 to turn off Manual
Shutter.
9.14.9
Take I-line probe off the aligner.
Disconnect the probe on the intensity meter. Turn off the power on the
intensity meter. Place everything back in order and store it back in the drawer
by the Karl Suss Aligner.
9.14.10
Press 3 to lower optical head.
9.14.11
Press Enter to return to the main
menu
10.0
Troubleshooting
Guidelines
10.1 During SEP and press CONT modes, the flow of gas out of the chamber can
make a hissing noise. If this happens, you may wish to press the CLEAR button,
unload the wafer, pull the wafer chuck out, and wipe the seal around the edge
of the chuck with a clean wipe.
10.2 No light during exposure. If this
happens, check the power on lamp power supply.
10.3 Wafer chuck gets stuck on mask.
Load wafer chuck up without wafer will make vacuum hold on to mask. If this happens, do the following under Main
Menu to release the vacuum:
10.3.1
Press 4- Controls.
10.3.2
Press Right Arrow → button.
10.3.3
Press 2 [ ] Chuck Vac Off.
10.3.4
Press Clear button.
10.3.5
Press ENTER button on UniOp to
return to Main Menu.
11.0
Figures
& Schematics
12.0
Appendices
12.1.1 After studying the Q4000 User Manual, potential new users should arrange
ahead of time to have an existing user review the MA operation. Casual
questioning (e.g. "Hey, can you review this with me for a moment?")
is not to be considered an official review period.
12.1.2 The first question that should be asked is whether Section 4.8 - Quintel Mask Aligner on the web and the
equipment header file has been thoroughly reviewed? If not, the current user
should insist that it be reviewed before the meeting.
12.1.3 The "meeting" between the current and new user should be
scheduled for enough time to explain equipment operation; Loading and unloading
the mask and substrate, top side alignment using the top microscope, back side alignment
using IR, the exposure process, and a review of system errors. (I cannot see
this taking less than 60 minutes as subtleties of the MA process are sure to
come up for discussion). Equipment time and dummy wafer should be recharged to
new users account.
12.1.4 Step 12.1.3 should be done at least twice with two different current
users.
12.1.5 Upon successful completion of Step 12.1.4, new users should take the MA
Users Test. Tests are administered by Microlab office staff, and are graded by
Microlab staff (Kim Chan). Estimate 2-5 days for grading. The idea of the test
is to simply make sure all new users understand the material. Satisfactory
completion of this test will enable the user to meet with a Superuser for
qualification.
12.1.6
Superusers will first ask, who
trained you? of the new user. Training implies adequately following Steps
12.1.1-12.1.4 above. The users identified as being the ones who did the
training will be responsible for the information conveyed by the new user
during the qualification. It is suggested that the test be reviewed with
another user while at the Quintel aligner tool before taking the final oral
qualification with the superuser.
12.1.7 Description of Alignment Target Placement An
optional standard spacing for the alignment marks is 76.2 mm or 3 inches apart
on a 4 substrate along the X-axis and center on the substrate along the
Y-axis. Use 51.15 mm or 2.25 inches spacing if backside alignment is needed.
Be sure to
know
.