ZnO micro- and nanostructures from Deep-UV photosensitive solutions for electronic and magnetic applications

Overview & Synopsis

In this thesis, an in-depth investigation to the photosensitive zinc methacrylate (ZnMAA) precursor was made. Zinc methacrylate can be crosslinked under DUV (193 nm) irradiation. The photo-induced solidification is attributed to the partial decomposition of the ZnMAA complex, which gives rise to the following hydrolysis-condensation reactions and the formation of Zn-O-Zn networks. The bonding variation and decomposition of organic species caused by DUV irradiation were carefully investigated by FTIR, XPS and ellipsometry and discussed in Chapter III. DUV irradiation provokes clivage of MAA ligands from zinc cations. However, the intensity of MAA ligands can only be reduced to ~2/3 of its initial intensity regardless the extension of irradiation time, implying only a small amount oxide network can be induced by DUV irradiation. The small amount of Zn-O-Zn networks inside the photo-irradiated regions can effectively decrease the solubility of photo-irradiated regions in polar solvents, which makes ZnMAA precursor just like a negative tone resist and able to be patterned into two-dimensional structures by DUV lithography. Due to good photosensitivity to DUV light (193 nm), the dimension of DUV-patterned ZnMAA structures can be decreased to sub-micro by using binary masks and the effects of each pattering step including (i) DUV exposure, (ii) prebaking and (iii) development on the size and shape of DUV-patterned ZnMAA structures are discussed in Chapter IV. In order to fabricate nanoscale ZnMAA structures, a home-made DUV interference system was used to pattern ZnMAA precursor and 300 nm periodic lines were successfully made. Applications as TFT transistor, gaz sensor and magnetic materials are shown.