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Tool owner: Roman Akhmechet, romana@princeton.edu, x 8‐0468 Backup: Eric Mills, enmills@princeton.edu, x 8‐4626,
Page 1 of 17
Heidelberg DWL66 Laser Writer Standard Operating Procedure
QUICK GUIDE
PROCEDURE OVERVIEW 1. Write head 2. Convert user layout file 3. Load sample 4. Using Basic Mode 5. Heidelberg Global alignment 6. Top‐side Beam offset calibration 7. Optical offset fix
CRITICAL PRECAUTIONS AND COMMON MISTAKES
Place your sample on stage before setting up exposure
Never touch the interferometer’s mirrors with your bare hands
Never open coverlid when an exposure job is running (you cannot resume it)
Write head center to the edge of your substrate must be ≥ 5 mm
Only users with legitimate need can mount/use/unmount 2 mm write head after training
and authorization by tool owner. The default write head is 10 mm.
Before you start
To purchase any masks/holders from MNFL, remember to fill in on the LOG Book. Preparation:
Pattern Files: GDSII, CIF, DXF, GERBER, or BMP (grayscale)
Samples: Fresh photomasks (MNFL supplies standard Cr masks with soda lime glass plates, both 4 inch and 5 inch in size, manufactured by Nanofilm) or substrate coated with photoresists (substrate OD must be ≥ 10 mm).
Tool condition for the next user Stage free of sample.
Return to default condition: 10 mm lens and 25 % filter, if any change made during
exposure.
Page 2 of 17
TOOL OVERVIEW
The Heidelberg DWL 66+ is a high resolution pattern generator for mask making and direct writing. Its
capabilities and flexibility make it an ideal lithographic tool for research. It uses acousto‐optic modulators
to adjust the laser intensity, and acousto‐optic deflectors to scan the beam. During an exposure, only the
stage moves. The substrate is held down on the stage by vacuum and moves in the x‐y plane. Its position
is constantly monitored by an interferometer system with a resolution of 10 nm.
The optical setup utilizes a single‐mode diode laser ( = 405 nm) as its light source. It can expose both 2D
and 3D structures (e.g. gray scale lithography with thick photoresists). There are two write heads available:
2 mm & 10 mm. Both heads are equipped with pneumatic sensor and optical sensor for auto focus. In
term of resolution, the 2 mm write head can achieve a minimum feature size of ~650 nm, the 10 mm head
can achieve a minimum feature size of ~1.4 m.
Page 3 of 17
FULL PROCEDURE
A) Write head
Write head Critical dimension Write speed
2 mm ~0.8 um 6 mm2/min
10 mm ~1.8 um 145 mm2/min
Only users with legitimate need can mount/use/unmount 2 mm write head after training and
authorization by tool owner. The default write head is 10 mm.
B) Convert user layout file
1. Use USB memory stick to transfer layout file and upload file to its corresponding folder shortcut on desktop (gdsii, cif, dxf or gerber). Note: if using gdsii, make sure the .gds is lower case in file name
2. Double click conversion icon on desktop to open GUI HIMT Convert window, select “File/New job” to create a new job. Job Name Guidelines: The job name should have no hyphens or spaces. There is a limit of 12 characters in the name. Please use your NEMO account name as first part of the job name. For an existing job, select “File/Load job” to load an existing job.
3. Under Source File, click “Add”, select
the file type to pick your file, a new
window will pop up with options
depending on the file type. Select the
correct structure/cell and layer number,
and then click “Create Default”. The
Main Status window should state No
Warnings, No Errors if the CAD file
loaded successfully
Page 4 of 17
4. Select the correct structure/cell and
layer number. These come from your
CAD and depend on how many layers
you have, what their GDS numbers are,
and what you named your cells. When
finished selecting cells and layers, click
“Create Default”.
5. The Main Status window should state
No Warnings, No Errors if the CAD file
loaded successfully
6. Click the checkbox “TCL view” to turn it
on. 7. Click “VIEWER” to inspect pattern with
HIMT Viewer.
8. You can click Fill button to fill in the areas that will be exposed. You can navigate around and zoom in and out. When done with the views, use the Exit button to close the window
Page 5 of 17
9. Select the correct “Write Lens” (Must
be the same as what is mounted on
tool.)
10. In the “Justification” tab, select “Automatic Centering” to center your pattern design. For masks also select “Mirror” at y to flip the design.
11. “Expose Options” tab has additional options for inversion and XOR functions, as well as CD biasing
12. Click “Complete Tasks” at the bottom,
then save the job. Click “Expose Offline”. Note: if you receive an error, please check that the name of your job complies with all of the guidelines from step 2.
13. Once the file transfer is finished, click “Finish” to complete file transfer.
Page 6 of 17
C) Load Substrate
Open the sash and turn on the light.
Open the filter panel and install the
correct filter for your process.
Place your sample on the center of
the stage. The sample must cover the
center holes because that is where
automatic focus occurs.
Pay attention to the coordinate
system inside the tool. (Positive Y to
the left, positive X away from the sash
and towards the back)
Page 7 of 17
Adjust white screws to open vacuum
holes appropriate to your sample.
From Right to Left, opening more
screws will increase how far from
center the vacuum is pulled
Follow the guide below to open the
right screws for your sample size. Ex:
for 5 mm chip, place it in the very
center and only open the rightmost
screw
Turn on the vacuum using BOTH black
knobs.
Note: In this tool, vertical is off and
horizontal is on
Close the sash and turn off the light
Page 8 of 17
D) Set up an exposure job and expose pattern using exposure wizard in basic user mode
Basic mode
1. Double click on Lithography icon on
desktop to prompt Lithography login
window. If the login window is ready skip
prior step. Login by choosing username:
DWL66+ Basic and password: basic66.
(If the exposure wizard does not appear,
click Wizardry ‐> expose wizard)
2. Switch to the correct “convertPC” tab on the top
3. Click on “Update” at the bottom left to refresh files.
4. Click on “+” to populate “General” folder and double click your job file to prompt Exposure Parameter window.
5. Find your design and double click it. This will take you to the parameter start step.
6. Select your parameters: ◦ Laser power should stay at 120 ◦ Choose intensity for your process ◦ Choose focusing mode: pneumatic
or optical ◦ Choose Focus offset setting
specific to your process ◦ Under “Automatic Centering”,
choose whether to center the job on your sample (PlateCenter for rectangular substrates, WaferCenter for wafers)
◦ Make sure “Laser Mode after Exposure” is Default
Page 9 of 17
7. Make sure your substrate is on the stage,
then click “Start Exposure” button at
bottom.
8. When the pop‐up shows up asking to load
the substrate, click “Ok”
9. NOTE: if there is another pop‐up asking to
mount the correct device, make sure the
correct write head is mounted on the tool,
and acknowledge by pressing “OK”
10. The tool will automatically focus, center
the sample, and perform the exposure.
11. When the exposure is complete, click “Ok”
in the pop‐up and unload your substrate.
12. When finished do not close the software. Instead, press File in the upper left corner, and “Change user” to logoff.
Page 10 of 17
APPENDIX A: GLOBAL ALIGNMENT
You must be trained by staff to use advanced features. This section describes procedure to perform
global alignment for rotation and translation of whole array to sample. You may need to perform beam
offset calibration if the results of alignment are poor. Contact staff with questions.
Note: if camera window is not present, open it by going to Devices ‐> Vision ‐> Camera and click green
“Live” button
1. Log in as User instead of Basic
2. Set up desired filter and write head. Place your sample on chuck with appropriate vacuum
3. On left in Job tab, select your job array or create a new one. Drag your design, modify array properties. You can use a single cell, or create a whole matrix of designs
4. Under SystemControl, select appropriate autofocus mode (pneumatic or optical)
5. Press “Center”
6. Press blue down arrow to autofocus
Page 11 of 17
7. Optional: find sample center with either wafer or plate auto‐centering
8. Open global alignment wizard: Wizardry
‐> Execute global alignment
9. Execute rotation alingment:
a. Using arrows for stage control (or type in coordinates directly), go to left alignment mark P1, center it on the camera screen
b. Click “Next Step” on the bottom c. On camera screen, click on mark
P1 d. Center on right alignment mark
P2 in camera screen e. Click “Next Step” on the bottom f. On camera screen, click on mark
P2 g. Click “Save and go to 0,0” OR on
“Save and start next iteration” to repeat step 9
Note: you want two marks total that are on the same horizontal in CAD. It can be a cross, or a corner, or any two arbitrary points that have the same global Y‐coordinate
10. Execute translation alignment a. On camera screen, center on a
feature with known X,Y global coordinate
b. Click “Set Zero” in middle of StageControl
c. Move back to center of CAD by translating stage by –X and –Y from the selected feature
d. Click “Set Zero” again e. Your origin is now aligned with
the origin of your CAD
11. At this point you can either create die‐by‐die script for alignment, or expose the job
12. To expose, hit green “Execute” button in Job tab
13. In the pop‐up box, click OK to turn on
laser
Page 12 of 17
14. After exposure has completed, click OK in pop‐up box to move write head to standby position
15. Click OK in process finished pop‐up box
16. The stage should unload automatically. But if it does not, click “Load” in SystemControl to unload the sample
17. Unload your sample, return default filter
and write head, log out by clicking File ‐> Change user
Page 13 of 17
APPENDIX B: TOP‐SIDE BEAM OFFSET CALLIBRATION
The cameras and the laser beam are not targeting the same spot on the stage. There is an offset built
into the software for the stage to move in order for the beam to be aligned with where the camera
center is. Every time the write head is moved, it is not placed perfectly into the same exact position, and
it is possible for this offset to drift over time. If your top‐side alignment is off by more than a couple of
micros, you can attempt to recalibrate the offset using procedure below. You will need to have a sample
with two layers and the second layer was exposed on the DWL66+ using global alignment.
1. Load your exposed and developed sample into the tool. Focus the write head down and navigate the stage to locate your alignment marks. It is best to find features with a corner that should have the same position between two layers if the alignment is perfect. In this example, the points of two arrows should be touching
2. Open the correction menu by going to
Wizardry ‐> Writehead ‐> Calibrate beam offset
3. If you are already looking at the mark
on the first layer, then click “Next Step” at the bottom
Page 14 of 17
4. Under camera, select “Micro”. Under measurement, select “Position Manual” Make sure Iterations is set to 1, and click “Execute Measurement”
5. On the camera screen, you will see a
green cross. Click on the vertex of the first layer that should overlap with the second layer.
6. Click “Next Step” if you are already
looking at the layer 2 point on camera
7. Select same parameters for layer 2, click “Execute Measurement” and on camera screen click on point on layer 2 that should be on the same position as in layer 1.
Layer 1 vertex
Layer 2 vertex
Page 15 of 17
8. Review the results. Make sure the measured offset and the new offset make sense. Click “Save and close”
After this calibration, expose your real sample. In general, this calibration is not necessary to perform for
each alignment unless you find gross misalignment. If your alignment still does not work after
calibration, contact Staff for help.
Page 16 of 17
APPENDIX C: OPTICAL FOCUS FIX
Occasionally the optical autofocus can skip past the optimal focus plane. If that happens repeatedly, try
using the procedure below to help the tool find proper focus.
1. Raise the write head by pressing the up button
2. Click on the “Fix” button on top and
input 65000 as the value, then click “Fix to”
3. Try focusing again. If you continue to
have issues, contact staff regarding your process.
Page 17 of 17
Version history
Draft Date Author Notes on changes
v.0.1 November 29, 2016
v.0.2 April 6, 2017 Sen Liu Whole procedure
v.0.3 11/1/17 Roman Added global alignment
V0.4 Nov 2018 Roman Update to C menu 1.8
V0.5 Jan 2019 Roman New chuck, screws schematic added
V0.6 Nov 2019 Roman Edits to conversion to clarify where buttons are.
V1.0 Jan 2020 Roman Added “device prompt”
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