Advantages of Soft Lithography

3 Photoresist Processing for Fabricating the Master Wafer and Casting PDMS against the Patterned 

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This technique is also suitable for templating and microfabrication and offers new prospects in the fields of soft lithography and micropatteming. As an advantage the polymeric templates can be easily removed by solution or pyrolysis. Various metals... 

Another option of soft lithography takes advantage of the optical transparency of PDMS UV radiation is used through the mold structure to cure a pre-polymer. This technique, as described by Choi et al. [44], is depicted in Figure 4.6b. First, a mixture of styrene monomer and UV initiator is prepared and spun onto a substrate. The monomer mixture is then partially polymerized by 10 min of UV exposure to increase its viscosity and avoid the PDMS being swollen by the monomer. Then the PDMS mold is placed on top of the substrate and full polymerization of the prepolymer is achieved by further exposure to UV light. By this technique, Choi et al. have reported polymer patterns of submicron dimensions, that is, lines 150 nm wide and dots of 770 nm in diameter. The fact that this is a process carried out at room temperature avoids problems such as the tendency of the PDMS mold to separate from the substrate due to differential thermal expansion. Because of their rapid polymerization with minimal change in volume, the monomers isobomyl acrylate... 

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