Specific Process Knowledge/Lithography/EBeamLithography/2D detection system: Difference between revisions
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== Reference images == | == Reference images == | ||
During alignment the system will take SEM images and compare these to reference images of the alignment marks. These reference images can in principle be SEM images obtained from the system but it is simpler to use black and white drawings of the alignment marks. In this example we will use a cross. | During alignment the system will take SEM images and compare these to reference images of the alignment marks. These reference images can in principle be SEM images obtained from the system but it is simpler to use black and white drawings of the alignment marks. In this example we will use a cross as illustrated below. | ||
{| style="border: none; border-spacing: 0; margin: 1em auto; text-align: center;" | {| style="border: none; border-spacing: 0; margin: 1em auto; text-align: center;" | ||
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Alignment mark used in this example. The mark is 1000 µm in both directions. | Alignment mark used in this example. The mark is 1000 µm in both directions. | ||
|} | |} | ||
The system must know the scale of the mark it is looking for, hence one must assign a physical dimension to the reference mark. The reference image must also be converted to a TIFF image. Both dimension assignment and conversion to TIFF is done with a command in a terminal window. In this example the actual mark is 1000 x 1000 µm and the input image is a PNG file called "PQRef1000mu.png". The command is: | |||
ebimg setsize inputimage.png outputimage.tiff dimension | |||
The dimension is given in nanometer. In the example the actual command is | |||
ebimg setsize PQRef1000mu.png PQRef1000mu.tiff 1000000 | |||
This will generate a TIFF file with a scale of 1000 µm. Next, this must be converted with yet another command to a .ref.gz file. The command is | |||
ebimg mkref inputimage.tiff outputimage.ref.gz | |||
In our case it will be | |||
ebimg mkref PQRef1000mu.tiff PQRef1000mu.ref.gz | |||
This will generate the actual reference image file with the correct scaling. This file should be moved to | |||