Specific Process Knowledge/Lithography/Aligners/Aligner: Maskless 01 processing: Difference between revisions
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The stage of Aligner: Maskless 01 has suffered some kind of damage (maybe during it's relocation to E-4 in 2019), which means the stage positioning is distorted. When aligning to a pattern exposed using a different machine, we typically see a shearing on the order of 0.1 | The stage of Aligner: Maskless 01 has suffered some kind of damage (maybe during it's relocation to E-4 in 2019), which means the stage positioning is distorted. When aligning to a pattern exposed using a different machine, we typically see a shearing on the order of 0.1 mrad, i.e. the axes are not orthogonal, but even when aligning to patterns exposed on Aligner: Maskless 01 itself, this distortion results in misalignment unless a specific procedure is followed. | ||
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* Use only 2 alignment marks and apply rotation correction | * Use only 2 alignment marks and apply rotation correction | ||
* Use 3+ alignment marks and apply all corrections (rotation, scaling and shearing) | * Use 3+ alignment marks and apply all corrections (rotation, scaling and shearing) | ||
<span style="color:red">If 3+ marks are used, but scaling and shearing is not applied, ''significant'' misalignment will be observed, even on chips. On a 4" wafer the shift in Y can be several hundred µm.</span> | |||
Using only two alignment marks (on the X-axis) is recommended when aligning to patterns exposed using Aligner: Maskless 01. When aligning to patterns exposed on a different machine, using 4 alignment marks and all corrections applied yields the best alignment accuracy. <br/> | |||
Using only two alignment marks is | |||
==Alignment tests== | ==Alignment tests== | ||