1. Usually a thin film which has to be structured is deposited on the substrate. It is also possible to structure the substrate itself.
2. The to-be-structured substrate is covered, e.g. by spinning, with an organic photosensitive resist which is sensitive for UV-light. In case of a positive photoresist the UV-exposed areas become soluble in an aqueous solution, thus creating a positive image.
In case of a negative resist the exposed areas crosslink to form a non soluble layer and the unexposed resist dissolves in the developer. thus creating a negative image.
3. The mask and substrate are placed in the light path of an UV-exposure tool and are automatically or manually aligned to each other. When the photoresist has been exposed to the UV-light, the pattern on the mask is transferred into the resist.
4.In the developing step the soluble parts of the exposed photosensitive layer are removed with a developer.
5. The pattern can be transferred into the substrate by etching either in a wet-chemical solution or in a plasma system (so-called dry etching)
6. Finally the remaining photoresist is removed by a
plasma stripper (IPC 9200 Barrel, Fusion) in case of a dry etch process or a solvent of aceton or
microstrip.
For realizing complex structures the above steps are repeated with care for a proper alignment
of the structures.
For a proper alignment the next pieces of equipment are available.