Latent image liquid development

Liquid toners are suspensions of toner particles in a fluid carrier. The carrier is typically a hydrocarbon. Dielectric, chemical, and mechanical properties of the Hquid must be compatible with the photoreceptor, the suspended toner particles, and the materials of the development equipment. Liquid toners are capable of producing higher resolution than dry toners because of the smaller (3—5 -lm) particle size achievable. Development of the latent image occurs as it passes through a bath of toner and the charged particles are attracted to the oppositely charged surface. 

The development process converts the latent image in the polymer into the final 3-D relief image. This process is perhaps the most complex of resist technology. It can generally be achieved by either liquid development or dry (plasma) development. Numerous considerations are critical to either alternative. We will first focus on the wet development process. Plasma development will be discussed in a later section. 

Plasma development derives its advantage over its liquid counterpart mainly from the anisotropic nature of the process, except when loss from the unexposed area is vanishingly small, in which case the isotropy comes from that already in the latent image. The resist must be tough to avoid being eroded completely while the substrate underneath is etched. To improve the plasma etch resistance, aromatic compounds have been added to PMMA (50, 51). Hence, for... 

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