Specific Process Knowledge/Lithography/Aligners/Aligner: Maskless 02 processing: Difference between revisions
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In order to get good alignment, it is advised to use four alignment marks for alignment, and to activate scaling (possibly also shearing) before starting the exposure. Optical or pneumatic auto-focus should not affect the result, but it is recommended to use the "High Res" camera for the final alignment of each mark in order to achieve the best overlay accuracy. Exposure using the fast mode decreases the overlay accuracy, since the address grid size is increased to 250 nm. | In order to get good alignment, it is advised to use four alignment marks for alignment, and to activate scaling (possibly also shearing) before starting the exposure. Optical or pneumatic auto-focus should not affect the result, but it is recommended to use the "High Res" camera for the final alignment of each mark in order to achieve the best overlay accuracy. Exposure using the fast mode decreases the overlay accuracy, since the address grid size is increased to 250 nm. | ||
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The result shows significant misalignment between the two layers, higher than what is seen in true overlay tests. This is believed to be an effect of drift during the first, long print (most likely heating of the stage), as the misalignment is seen to be biggest between parts printed furthest apart in time (i.e. on the left side of the wafer). In a normal overlay print, this error can be at least partially compensated using the scaling and shearing function available for three or more alignment marks/positions. | The result shows significant misalignment between the two layers, higher than what is seen in true overlay tests. This is believed to be an effect of drift during the first, long print (most likely heating of the stage), as the misalignment is seen to be biggest between parts printed furthest apart in time (i.e. on the left side of the wafer). In a normal overlay print, this error can be at least partially compensated using the scaling and shearing function available for three or more alignment marks/positions. | ||
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