Specific Process Knowledge/Lithography/Aligners/Aligner: Maskless 03 processing: Difference between revisions
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=Process Parameters= | =Process Parameters= | ||
... | The lithographic result of exposure on Aligner: Maskless 03 depends on a lot of factors, including the dose and defocus parameters, and the exposure mode used. The optimal dose and defocus depend on the type and thickness of the resist, and the optical properties of the substrate (e.g. reflective/absorbing/transparent). All of these factors influence the obtainable resolution, as well as the writing speed. | ||
The correct way to determine the best dose-defocus settings is to generate a so-called Bossung plot (known from projection lithography), which plots the printed linewidth as a function of dose and defocus. From this, the most stable region of parameter space is chosen, i.e. the region where the linewidth changes the least when dose and defocus changes. Any deviation from the design linewidth may be corrected using the CD bias parameter. This typically involves SEM imaging of resist cross-sections, and quickly becomes time consuming. However, in most cases, inspection of a dose-defocus matrix (easily generated using the series exposure function) in an optical microscope will get you most of the way. | |||
==Exposure mode== | ==Exposure mode== | ||
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In the fast mode, each area of the pattern is exposed by 2 stripes only. This reduces the exposure time by 60%, but also increases the size of the address grid in the X-direction to 250nm. This means that alignment will be less accurate in fast mode. Due to less averaging of non-uniformities, stitching effects will be more prominent in this mode. | In the fast mode, each area of the pattern is exposed by 2 stripes only. This reduces the exposure time by 60%, but also increases the size of the address grid in the X-direction to 250nm. This means that alignment will be less accurate in fast mode. Due to less averaging of non-uniformities, stitching effects will be more prominent in this mode. | ||
==Writing speed== | |||
According to specs, the writing speed of Aligner: Maskless 02 is 285mm<sup>2</sup>/min in fast mode. Using the high quality exposure mode cuts this speed in half, to approximately 140mm<sup>2</sup>/min. The writing speed for a 100x100mm<sup>2</sup> area measured during installation of the machine (acceptance test) was ~340mm<sup>2</sup>/min for both exposure wavelengths. | |||
==Acceptance test== | |||
Acceptance criteria on a 100 X 100 mm<sup>2</sup> area: Width of smallest resolved line 600±100 nm, alignment error 500 nm, writing speed 285 mm<sup>2</sup>/min. | |||
The acceptance test also included a verification of back side alignment (better than 1 µm), as well as | |||