Specific Process Knowledge/Lithography/EBeamLithography/JEOLAlignment: Difference between revisions

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 =Global alignment - SETWFR=
 The next step is to verify that it is possible to detect the P and Q marks, this is done with the '''SETWFR''' subprogram. Select it and edit the parameters.
-Set the '''Measurement mode''' to '''Auto'''. Make sure that '''Material type''' is set to '''Wafer'''. Set the '''Material size''' and '''Multi-piece window''' correctly to your exposure. In the '''Material center offset position''' fields enter the P mark offset as found from the prealigner. Enter the P and Q mark design coordinates in the last four fields. Based on the chosen window, the design coordinates and the prealigner offset, the system now knows where to look for the P mark.
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 The '''SETWFR''' window and '''Settings''' scan condition windows. Image: Thomas Pedersen.
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+Set the '''Measurement mode''' to '''Auto'''. Make sure that '''Material type''' is set to '''Wafer'''. Set the '''Material size''' and '''Multi-piece window''' correctly to your exposure. In the '''Material center offset position''' fields enter the P mark offset as found from the prealigner. Enter the P and Q mark design coordinates in the last four fields. Based on the chosen window, the design coordinates and the prealigner offset, the system now knows where to look for the P mark.
+Next, the scan parameters have to be set. There are four sets of scan parameters to set:
+*P mark rough scan
+*P mark fine scan
+*Q mark rough scan
+*Q mark fine scan
+The rough scan conditions are used to scan over several 100 µm to find the mark while the fine scan conditions are used to accurately determine the center in as small a window as possible. Edit the P mark rough conditions by clicking its '''Setting''' button. Set the scan position x and y to about half the size of the mark, in this case 250 µm. Set the scan width in x and y to 400 µm to scan a large area with a high chance of finding the mark. If the contrast of the mark is not optimal the number of scans or the scan clock (beam dwell time) can be increased. Go to the '''Offset''' pane and make sure all offsets are set to zero. Go to the '''Scan type''' pane and set the mark width and mark length according to the mark, in this case 20 µm and 500 µm, respectively. The mark width is the most important as the system will only acknowledge a feature of the stated dimension to be the mark. Close the window on '''OK'''.
+Also edit the fine scan conditions of the P mark. The windows are essentially identical, the only difference is the dimensions as we now want to scan a much smaller area in order to pinpoint the mark center with as high accuracy as possible.