DUV interferometry for micro and nanopatterning

In recent years, fabrication of chemical and topographical functional materials in the micrometer and nanometer scales has been drawing a great interest in the scientific community. The attention is not only due to the need for ever-increasing miniaturization of microelectronics for example, but also because of the discovery of many novel phenomena that occur at these scale levels. Recent advances in micro- or nano-fabrication techniques have been reported in the literature. The size of the patterns is strongly dependent on the technique used and can range from micrometer to sub-10 nanometer scale. Among the suitable techniques, DUV lithography has proved its interest since it is compatible with nanoscale fabrication on large surfaces (typ. few cm
²
) with limited writing times. However, there is a need to develop new materials suitable with DUV lithography in terms of resolution, line edge roughness (LER) and properties (mechanical, optical, etc.). Patterns were generated by DUV irradiation using an ArF excimer laser. A phase mask grating with a binary profile especially designed to minimize the zeroth diffraction order was used. The phase masks were irradiated in normal incidence and creation of a sinusoidal distribution of light by interference between two coherent beams (Fig. 2). The plusmn1 diffraction orders generated by the phase mask recombined within the thickness films, creating a sinusoidal distribution of light that was used to induce the surface patterning of the film. Typically, the surface was irradiated with good homogeneity. In order to avoid the contact between the phase mask and the film, spacers were used (60 mum thickness). We have developed several materials based on both organic and inorganic functionalities that suitable for nanofabrication in the DUV range. We will illustrate the principle of DUV interferometry and demonstrate its interest for patterning several materials for applications in optics, photonics and biology.