Specific Process Knowledge/Lithography/Aligners/Aligner: Maskless 04 processing: Difference between revisions

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-During load, the machine will focus on the surface of the sample. Then, using the pneumatic focusing system, it will detect the edges of the sample (this function dependes on the substrate template used) in order to determine the center of the sample. The following results rapport findings using the "4 inch wafer" template on a standard 100mm Si substrate.
+During load, the machine will focus on the surface of the sample. Then, using the automatic focusing system, it will detect the edges of the sample (this function depends on the substrate template used) in order to determine the center of the sample. The following results rapport findings using the "4 inch wafer" template on a standard 100mm Si substrate.
-==Substrate centring==
+==Substrate centering==
-During (4") substrate detection, the sample is scanned along the X- and Y-axes, as well as diagonally. From these measurements, the diameter of the substrate is calculated, as well as the stage position matching the center of the substrate. This stage position will be the default origin for the subsequent exposure.
+During (4") substrate detection, the sample is scanned diagonally. From these measurements, the diameter of the substrate is calculated, as well as the stage position matching the center of the substrate. This stage position will be the default origin for the subsequent exposure.
+<br/>The result of testing the centering on a couple of wafers has shown offsets of the centering in excess of 0.5mm. This is worse than the results observed on MLA 1, 2, and 3.
 ==Flat alignment==
-At the end of (4") substrate detection, the sample is scanned twice along the flat, in order to determine the substrate rotation. This angle will be presented in the exposure panel along with the option to expose the design rotated in order to compensate for this angle, i.e. aligned to the flat.
+At the end of (4") substrate detection, the sample is scanned twice along the flat, in order to determine the substrate rotation. This angle will be presented before exposure start along with the option to expose the design rotated in order to compensate for this angle, i.e. aligned to the flat.
-<br/>The flat alignment accuracy has been measured to be 0±0.1° (1.7mRad) quite consistently. Out of a total of 15 exposures, 13 showed misalignment of 0.1° or better, despite initial sample rotations exceeding 5°.
+<br/>The result of testing the flat alignment on a couple of wafers has shown the alignment to be within ±0.1° (1.7mRad). This matches the results observed on MLA 1, 2, and 3.
 Please observe, that one should not select the flat alignment option if 'Expose Crosses' is used. The design will be rotated, but the crosses will not, resulting in a subsequent alignment error equal to the flat angle.