Specific Process Knowledge/Lithography/Aligners/Aligner: Maskless 02 processing: Difference between revisions

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 Aligner: Maskless 02 is configured with the so-called "Write Mode I", which uses a higher demagnification, higher NA lens system to achieve higher resolution. This reduces the depth of focus (technically ''depth of field''), making it more difficult to achieve good lithographic results in thicker resist coatings. The theoretical DOF of Aligner: Maskless 02 is 0.3µm, compared to 1µm for Aligner: Maskless 01. In order to enable processing of thick resists, the Aligner: Maskless 02 has been configured with the High Aspect Ratio Mode, which uses a variable aperture in the optical path to decrease the (illumination) NA of the system, thus increasing the DOF at the expense of intensity and resolution limit.
+Decreasing the aperture size significantly reduces the amount of light that reaches the sample, and thus the effective dose, as can be seen in the graph to the right, and the table below. The resolution, however, seem sto much less affected. Tests using 1.5µm MiR resist suggest that using the X-Large setting (aperture: 60 steps) reduces the achievable resolution from 1µm at standard setting (fully open; 800 steps) to 3µm for exposure at 375nm, and only 1.75µm for exposure at 405nm.
 [[Image:MLA150_intensityVSaperture.JPG|300x300px|thumb|The exposure intensity of Aligner: Maskless 02 as a function of the high AR mode aperture setting]]