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| Example of beam offset matrix shown during auto calibration. Average beam offset is below 1 nm within the 1000 x 1000 µm<sup>2</sup> writing field in this example. Image: Thomas Pedersen. | | Example of beam offset matrix shown during auto calibration. Average beam offset is below 1 nm within the 1000 x 1000 µm<sup>2</sup> writing field in this example. Image: Thomas Pedersen. |
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| == Table of subprograms to execute during calibration ==
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| Calibration of condition files normally consists of a number of subprograms listed in the table below. The subprograms listed in the blue part of the table are a part of the 'daily' batch of programs.
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| !colspan="2"|Calibration of condition files
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| !style="width: 25%"|Subprogram
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| !Explanation
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| !style="background:#ADD8E6; color:Black"|CURRNT
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| |The stage moves the Faraday's cup to the beam and the machine reads the value of the cup. The machine measures the beam current 5 times and calculate the average of the beam current based on these 5 measurements.
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| !style="background:#ADD8E6; color:Black"|INITAE
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| |The AE marks (Absorbed Electrons) is a mark type that is connected to a pn-junction, i.e. the current abosrbed in the mark is measured. The AE mark is a knife-edge mark, i.e. is has (originally) very sharp edges. When the beam (with a well-known frequency) scans over this type of mark and absorbed current simultanously is measured, an estimate of the beam diameter can be found. '''INITAE''' is a subprogram that finds the AE mark and scans it for testing that the machine can find the mark.
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| !style="background:#ADD8E6; color:Black"|INITBE
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| |The BE mark (Backscattered Electrons) is a mark type that consists of a suspended grid of metal. The openings in the grid is 500 microns in both X and Y. When the beam scans over this type of mark, backscattered electrons are detected with the BE detector inside the chamber. This type of mark is used to correlate stage position and beam position during calibration. '''INITBE''' is a subprogram that find the BE mark and scans it for testing that the machine can find the mark.
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| !style="background:#ADD8E6; color:Black"|[[Specific_Process_Knowledge/Lithography/EBeamLithography/JBX9500Manual#SFOCUS|SFOCUS]]
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| |This subprogram finds the minimum beam diameter by scanning an AE mark while changing the focus of the objective lens. The objective lens is defined to be in focus where the machine finds the minimum beam diameter. This program can also be used to observe the depth of focus of a certain condition file. '''The SFOCUS''' subprogram does not work well for currents above 6 nA, why SFOCUS is deleted in 'daily' routines of condition files with currents larger than 6 nA.
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| !style="background:#ADD8E6; color:Black"|[[Specific_Process_Knowledge/Lithography/EBeamLithography/JBX9500Manual#PDEFBE|PDEFBE]]
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| |Using a BE mark, this subprogram corrects deflection gain and rotation of the main deflector. The system positions the BE mark in the corners of the main field (which is a 1000 x 1000 µm2 square) and scans the mark using the primary deflector only.
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| !style="background:#ADD8E6; color:Black"|[[Specific_Process_Knowledge/Lithography/EBeamLithography/JBX9500Manual#DISTMEM_and_DISTBE|DISTMEM]]
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| |This subprogram measures the distortion of the beam deflection 7 x 7 positions within the main writing field and generates a distortion correction table. The system positions the BE mark in all 49 positions and uses only the primary deflector to scan the BE mark in every 49 positions. The program sets the distortion directly below the beam (center of the field) to zero. The distortion correction memory in every position in the main writing field is generated by a linear approximation based on the 7 x 7 table. For 0.2 nA or 2 nA, a reasonable convergence value is e.g. 6 nm.
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| !style="background:#ADD8E6; color:Black"|[[Specific_Process_Knowledge/Lithography/EBeamLithography/JBX9500Manual#DISTMEM_and_DISTBE|DISTBE]]
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| |This subprogram measures the distortion of the beam deflection 7 x 7 positions within the main writing field and generates a distortion correction table. The system positions the BE mark in all 49 positions and uses only the primary deflector to scan the BE mark in every 49 positions. The program sets the distortion directly below the beam (center of the field) to zero. The distortion correction memory in every position in the main writing field is generated by a cubic approximation based on the 7 x 7 table. For 0.2 nA or 2 nA, a reasonable convergence value is e.g. 8 nm.
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| !style="background:#ADD8E6; color:Black"|[[Specific_Process_Knowledge/Lithography/EBeamLithography/JBX9500Manual#SUBDEFBE|SUBDEFBE]]
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| |Using a BE mark, this subprogram corrects deflection gain and rotation of the secondary (sub) deflector. The system positions the BE mark in the corners of the subfield (which is a 4 x 4 µm2 square) and scans the mark using the sub deflector only.
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| ![[Specific_Process_Knowledge/Lithography/EBeamLithography/JBX9500Manual#DRIFT|DRIFT]]
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| |This subprograms scans the DRIFT mark. The DRIFT mark can either be a BE mark or an alignment mark on the substrate. By scanning the DRIFT mark during exposure, the machine can positionally adjust the exposed pattern during writing, i.e. positional drift due to cassette heat-up or warm-up during writing can be corrected. This is done by using the the path DRF5M in the jdf-file.
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| ![[Specific_Process_Knowledge/Lithography/EBeamLithography/JBX9500Manual#HEIMAP|HEIMAP]]
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| |This subprogram measures the height of the substrate to be exposed. The size and workpiece position of the substrate (e.g. 4B) should be entered along with information of desired area to measure height. This area should always be larger than the area of the exposed pattern. The system will focus the beam to the average of the height mesaured in HEIMAP, but '''only''' if you expose in mask writing mode (i.e. no aligning) and execute HEIMAP in your initial calibration (e.g. by using path DRF5M).
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| ![[Specific_Process_Knowledge/Lithography/EBeamLithography/JBX9500Manual#SETWFR|SETWFR]]
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| |This subprograms scans the global marks of the substrate. You need to enter the theoretical positions of the global marks (in wafer coordinate system) and the offset found during pre-aligning. When SETWFR has succeeded in finding your global marks, it will give you a corrected offset, that should be entered in your sdf-file.
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| ![[Specific_Process_Knowledge/Lithography/EBeamLithography/JBX9500Manual#CHIPAL|CHIPAL]]
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| |This subprogram scan a set of chip marks on the substrate. You need to enter theoretical position of a chip on your wafer (in wafer coordinate systems) and the theoretical positions of the chip marks on that chip (in chip coordinate system). CHIPAL will then scan 1 or 4 chip marks (mode 1 or mode 4).
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| |}
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| <br>
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| ==Measure stage drift== | | ==Measure stage drift== |
