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Photosculpting the photoresist (or other photosensitive materials) by spatially variable exposure
The thickness of the photoresist after development depends on the local dose of UV irradiation
Local dose is adjusted to take into account the non-linear photoresponse of the particular photoresist and proximity effects
The development time and conditions must be carefully controlled to achieve the desired “analog” photoresist profile; the economic advantages of patterning photoresist using a gray scale mask over laser beam direct write or e-beam direct write on photoresist is apparent even for the fabrication of a single mold surface for injection molding. This is because a gray scale mask enables economic optimization of development time and conditions to obtain the most desired analog resist profile in the presence of many variable parameters of photoresist and lithographic exposure conditions.
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