Photoresist film, relief images

In 1979, Smith and co-workers described the development of a system they called PDF (which presumably stands for Plasma Developable Photoresist) that is based on the use of a material, the structure of which has not yet been divulged 61). In this process the resist is coated in the usual fashion and exposed optically. The exposed film is then subjected to a baking cycle that produces a relief image of negative-tone that is, depressions are generated in unexposed areas (Figure 45). This relief structure is... 

Photoresists are photosensitive films used for the transfer of images onto a substrate (60). A coating layer of a photoresist is formed on a substrate and the photoresist layer is then exposed through a photomask to a source of activating radiation. Exposure to radiation provides a photoinduced reaction in the coating layer. After exposure, the photoresist is developed to provide a relief image that permits selective processing of a substrate. 

Novolac polymers are soluble in a variety of common organic solvents. Resist films are typically cast from organic solutions (propylene glycol monomethyl ether acetate, or PGMEA, is a common solvent) to form isotropic, glassy, thin films. These polymers are also soluble in aqueous alkaline solutions due to the presence of the acidic phenolic functionalities on the polymer backbone. It is this base solubility that is exploited in the development process. In order to print a relief image in a photoresist, it must be possible to modify the dissolution rate of the resist upon exposure to radiation. It is not the... 

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