Specific Process Knowledge/Lithography/EBeamLithography/RaithElphyManual

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Purpose, location and technical specifications

The Raith computer is located right next to the LEO SEM pc

The Raith Elphy system is a pattern generator built onto the LEO Scanning Electron Microscope (SEM) in cleanroom F-2. All users must therefore acquire license to use the SEM LEO before acquiring license to the Raith Elphy system.

Remember that you need two additional trainings from Danchip staff in order to be able to use this tool for lithography. Please refer to the General Page for further information.

The Raith ELPHY Quantum software (from now on, Elphy) is installed on the Raith pc located right next to the LEO SEM pc. The workstation is more or less independent from the LEO itself. If you try to access Elphy without properly setting up the microscope first, it will usually return a communication error, but it would still be partially functional e.g. to prepare layouts and position lists. When you want to do actual patterning, you will need to operate on both computers at the same time.

The pc has limited access to internet and the network. To import and export files on the Raith pc, two options are available:

• Send the files to yourself on your DTU email. You can then access and download them from the DTU webmail page
• For more advanced functionality, use the Citrix page with your DTU login. You can then use Citrix's Remote desktop??? or Explorer app??? to operate and transfer files between the local pc and your personal M: drive.

Preparation

You need to import your layout in Elphy before patterning your sample. The software contains a proprietary layout editor in which you can import, view and edit your designs afterwards.

The editor reads and produces single .gds or .csf files. To design your pattern you can use L-edit, Clewin or other CAD software. Try to limit yourself to a simple pattern for your first training, such as parallel lines or arrays of dots/squares, with variable size and pitch.

Access the software by using the username and password provided during your first training. As mentioned before, you can do this at any time, with or without operating also to the SEM LEO (just ignore the error). Go to Design () and Open your already prepared layout or click on New and use the GDS editor to design a new one.

Some useful information:

• If you have a layout with significantly different feature sizes, place finer structures on a different layer than the bigger ones, in order to be able to pattern them with different doses.
• Do not use layer 61, 62 and 63 for your features. These are connected to special functions inside Elphy.
• Elphy's editor saves additional information such as dose modulation. During the import/export procedures some of them may be lost or modified. Always double check your layout after importing it.

When you are ready to pattern, log on the LEO SEM computer on LabManager and start the imaging software as usual, and then start Remcon32, which can be found on the microscope's PC desktop. Right click in the black terminal and select Open -> Port 6???, then right click again and Open Port.
Move to the Raith pc and start ELPHY Quantum with your username and password.
If you did everything right, multiple lines of code will appear in the Remcon32 terminal and Elphy will start without prompting any error.

Mounting of chips or wafers into chamber

It can be difficult to align the beam properly to a chip coated with e-beam resist. It is thus recommended to remove the resist on a corner of the chip, preferably a place on the chip where you easily can adjust the beam, i.e. on metallised structures on the chip.

1. Ventilate the SEM chamber
2. Mount your chips(s) on the Raith Specimen holder
3. Mount the holder on the SEM stage, evacuate the SEM chamber

	Chip holder to Raith Elphy E-beam writer system; the holder has three clamps to hold up to 3 chips and a Faraday's cup to measure beam current. The holder is equipped with a dovetail that fits to the stage of the SEM.

Software login

1. Start the Raith ELPHY Quantum software from the desktop of the Raith computer (screen to the right).
2. Login with the following password:

User ID          
Password         

1. Start RemCon32 from the desktop on the SEM computer (screen to the left), choose 'COM 6', right-click and press 'start'

Preparation of a pattern file, GDS

You can either draw your pattern in L-edit, CleWin or AutoCAD and import the GDS file to the Raith computer. In that case it is important to flatten your design; the Raith software does not like instances.

You can also draw your pattern in the Raith software by clicking the 'Design' icon:

Pepare beam for writing

Before you start preparing your beam, a few recommendations:

• It is recommended to move the stage (by joystick) instead of deflecting the beam (ctrl + tab); this to ensure that you work with an undeflected beam while preparing the beam for patterning and while patterning your GDS.
• It is recommended not to rotate the scan by the 'scan' knob; this...

1. Measure beam current:
   1. Click 'Stage Control/Positions/Faraday's cup', make sure the stage moves to the center of the Faraday's cup, increase the magnification to 100.000x or more
   2. Toggle beam blanker to switch on beam
   3. Make sure you operate at a working distance of 5 mm
   4. Click 'XX' to measure beam current
2. Move the stage to a corner of your chip. With the joystick (or from the 'stage' tab in the SEM software), rotate the stage to align the chip
3. Adjust beam quality, i.e. focus, astigmatism, wobbling at a magnification of 100.000 x or more
4. Move to a new spot on the chip and switch the SEM to 'spot mode'; burn a spot in the resist (approximately 20s). Correct astigmatism and aperture alignment on that spot.
5. Burn a spot with a larger magnification and adjust beam quality again.
6. Burn a spot at a lower magnification to see that the spot is circular at this magnification

Stage adjustment

XY is stage coordinate system, UV is sample coordinate system:

1. Origin correction:
   1. Click 'Adjustment/Adjust UV/Origin correction'
   2. Move the stage to the lower left corner of the chip
   3. Enter (U,V)=(0,0) and click 'adjust'
2. Angle correction:
   1. Click 'Adjustment/Adjust UV/Angle Correction', make sure the system is in 'Global' mode
   2. Turn on the crosshair (SmartSEM/View)
   3. Set magnification to approximately 100x
   4. turn off beam and click 'Label1/flash'-icon to move stage to the origin.
   5. Click 'label1/pippette'-icon
   6. Move stage to the lower right corner of the chip
   7. click 'label2/pipette'-icon.
   8. Click adjust: the button hereafter turns green

Exposing

1. Click 'Design/open' to open a GDS file. Click 'View/Hierarchy/Max' from the menu bar to see full structure
2. Set the writing field:
   1. Click 'Raith/Writefield Manager', right-click on the writing field you wish to use and click 'SET'
3. Click 'File/Positionlist' and drag your GDS-file to the position list.
4. Right-click on the pattern name in the positionlist and click 'properties':
   1. Enter center position of pattern in (U,V) coordinates
   2. Click 'Layer' and select layers of the pattern to expose
   3. Click 'Patterning Parameters', click the calculator icon.
   4. Select Area/Line/Dot and enter area dose/line dose/dot dose.
   5. Enter step size (beam shot pitch) and line spacing for area/line/dot
   6. Click calculator icon again, click 'OK' when 'OK' is highlighted
5. Go to the positionlist, right-click on the pattern to expose and select 'Properties/patterning parameter/Times'
6. Activate the positionlist.
7. Click 'Scan/selection' from the menu bar. Exposure will start.