Spin coating wetting

Fig. 8.7 Fabrication sequence of a polymer microring resonator (a) prepare a nanoimprint mold (b) spin coat a polymer thin film (c) perform nanoimprinting process (d) separate the sample from the mold (e) dry etch the residual layer (f) create pedestals by wet etch...

Para-t-butylphenyl glycidyl ether BPGE had a similar viscosity and C/O ratio as those of NA and had the best properties of the photocurable epoxies that were surveyed, but this monomer dewetted from Si substrates immediately after spin coating and formed a puddle at the substrate center. Other monofunctional epoxies exhibited the same behavior. Mixtures of BPGE with multifunctional aromatic epoxies wetted Si substrates and could be used as planarizing layers. 

Another important aspect is the proximity of particle layer and thin or thick films, whereby the border between thin and thick films remains ambiguous. Conventional processing of particle assemblies comprises molding of the particle mass, like dry compression or wet casting. In the case of nanoparticles, to form a film is much more rational than conventional powder processing. In a dry procedure, production of nanoparticles and film formation in most cases take place simultaneously. An assembly of nanoparticles can also be formed in a wet procedure by precipitation on the templates or even by simple dip or spin coating from a sol containing nanoparticles. 

In a first step, the negative working photoresist SU-8 is spin-coated on to the disk and soft baked [110]. The disk is then UV-exposed to pattern the bottom layer. A silver thin metal layer is thereafter evaporated. The metal layer is spin-coated with an AZ-type photoresist, dried, exposed and developed. In this way, the metal layer can be developed independently from the patterning of the SU-8 layer underneath. The metal layer is patterned by wet-chemical etching. As a next step, a second SU-8 layer is deposited, soft-baked and exposed. Top and bottom layers are now developed. After a hard bake, a second CaF2 disk is attached to the stack and sealed by a light-curing epoxy resin. 

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