Specific Process Knowledge/Lithography/EBeamLithography/JEOLAlignment: Difference between revisions
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==Auto Gain Correction - AGCRG== | ==Auto Gain Correction - AGCRG== | ||
Alignment is done by scanning the beam over the alignment marks and recording the backscatter electron intensity. Thus, it is essential that the gain of the detector system is set to match the substrate material, the mark material and the beam current. The system can automatically optimize the gain of the backscatter detector through the '''AGCRG''' subprogram. Bear in mind, it is not always possible to get sufficient signal. Al alignment marks on a Si substrate will for instance basically never work since the atomic number and hence backscatter intensity of the two materials are almost the same. | Alignment is done by scanning the beam over the alignment marks and recording the backscatter electron intensity. Thus, it is essential that the gain of the detector system is set to match the substrate material, the mark material and the beam current. The system can automatically optimize the gain of the backscatter detector through the '''AGCRG''' subprogram. Bear in mind, it is not always possible to get sufficient signal. Al alignment marks on a Si substrate will for instance basically never work since the atomic number and hence backscatter intensity of the two materials are almost the same. | ||
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| [[image:AGCRG.png|400px]] || [[image:AGCRG_markcondition.png|400px]] | |||
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Setup of the AGCRG subprogram. Image: Thomas Pedersen. | |||
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Choose the '''AGCRG''' subprogram from the calibration menu and edit the properties to set it up correctly. In order to optimise the gain it is naturally vital that the beam is actually scanning a mark. The easiest way to ensure this is to use the P mark stage coordinate from the prealigner output file. To do this, set the '''Stage shift classification''' to '''Stage coordinate system''' and enter the P mark stage coordinates from the prealigner in the '''Mark position''' fields. | |||
Edit the scan conditions on the '''Settings''' button. | |||
In the '''Scan''' pane one can set the '''Scan position''' and '''Scan width''' to suitable values for the mark in question. In general one should scan a cross at a position half way from the center and at least a width of 300 µm to be sure to hit it. In the '''Offset''' pane make sure the offsets are all set to zero. Click '''Ok''' and execute the scan. | |||