Fabrication Of High-Resolution Conducting Polymer Nanostructure

Conducting polymer patterns with the feature sizes of micrometer to nanometer have recently received much attention because of their unique properties. With these years of research and development, conducting polymer patterns have been widely applied in many areas, such as field-effect transistors (FETs), light emitting diodes, electrochromic devices, and sensors. A number of techniques have been successfully demonstrated for formation of the patterned conducting polymer; for example, photolithography, microcontact printing, e-beam writing, scanning probe writing. However, these methods are high costs, time consuming, and not suitable for large area fabrication. Therefore, to develop a method which can quickly pattern conducting polymers with high resolution on large area is necessary.Edge lithography is able to change the large size structure to the small size. In the embossing process, the edges of a stamp become the features of the resulting pattern. So the resolution of the resulting structure is enhanced greatly. Both the nanoimprint (NIL) and the microcantact printing can achieve the edge lithography effect. Because of its low cost, short time-consuming, high reproducibility, NIL has been focused on fabricating high resolution structures on large area. But the high resolution stamps are expensive and need more preparation time. This restricts the applications of NIL. For microcantact printing, short time-consuming and low cost are main advantages, but the resolution is low. Edge lithography can use low resolution stamps to fabricate high resolution structures. This provides a good way to solve the problems.In this thesis, we aimed on the development of the efficient fabrication methods with low cost.Firstly, we used thin PMMA film as resist layer. The resist layer will rise up to a certain degree along the edge of the stamp and remain a certain stage because it is not fully filled in the trench. Then combining with the isotropic plasma etching, the resolution can reach a high degree. The widths of the conducting polymer lines are below 100 nm.Secondly, we used uncompletely cured PDMS structures as stamps in the microcontact printing to fabricate high resolution lines on the substrate. Then using the lines as a template, we deposited PANI on it. The PANI pattern can be transferred to the tape due to its adhesion is different between hydrophobic region and hydrophilic region. The width of the low molecular PDMS residues is about 100 nm, so the width of PANI lines is 100 nm.In conclusion, two methods based on edge lithography for achieving high resolution conducting polymer patterns were introduced in this thesis, which can greatly reduce the cost.