Generations of periodical nanopatterns by soft-mask assisted photolithography


Student thesis: Doctoral Thesis

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  • Ming FANG


Awarding Institution
Award date2 Oct 2015


Nanostructured arrays have been extensively explored for widespread applications such as photonic crystals, plasmonics, photovoltaics, LEDs, optical storages, biological/chemical sensors and functional textured surfaces. Conventional lithographic techniques, including deep-UV stepper lithography, electron-beam lithography and focused ion beam lithography, have been employed as standard methods for fabrications of high-quality nanopatterns. However, they are too expensive or slow for large-area fabrications for practical non-ICs (integrated circuits) applications. Newly developed techniques, such as laser interference lithography and nanoimprinting have also been used, but they need complex calibration systems and special skills to implement. In this thesis, I demonstrate a soft-mask-assisted photolithographic technology that allows facile fabrication of periodic nanopatterns over large areas with good controllability and reproducibility, and without the use of complex and expensive optical facilities. In this method, conformable transparent polymer films which are derived from self-assembled colloidal monolayers are employed as photomasks to assist the area-selective exposure of photoresist upon flood UV illumination. By simply controlling the exposure dose and development time, different patterns can be produced by using one single mask. Specifically, the thesis will includes the following technological aspects: (1) The preparation of highly ordered nanosphere monolayer; (2) Fabrication of surface textured soft polymer (polydimethylsiloxane, PDMS) masks ia a double-casting method; (3) Applying finite difference time domain (FDTD) simulations to assess the feasibility of soft masks for photolithographic applications; (4) Utilization of the surface textured soft masks to generate nanopatterns, exploring the factors that affect the geometrical features of the generated patterns and assessing the reliability of the fabrication method; (5) Fabrication of soft polymer films confined colloidal spheres and employing them as photomask for rapid wafer-scale nanopattern generations; (6) Pattern transfer for plasmonic and photovoltaic applications.

    Research areas

  • Nanotechnology, Photolithography