Periodic sub-micrometric structures using a 3D laser interference pattern

M. Salaun (1) , A.-L Joudrier , M. Audier (1) , S. Pignard (1)

1 LMGP - Laboratoire des matériaux et du génie physique

A method to obtain three-dimensional sub-micrometric periodic structures is presented. The experimental setup consists in a pulsed UV laser beam source (l = 355 nm) coming into an interferometer in order to generate four beams converging inside a chamber. According to the directions, to the relative intensities and to the polarizations of these four beams, a 3D interference pattern can be obtained inside the overlapping volume of these four beams; the characteristics of the four laser beams have been optimized in order to obtain a maximal contrast of intensity. In order to visualize the interference pattern, its contrast and its stability at each laser pulse, a video camera coupled to an oil immersion microscope objective has been installed above the interferometer. By suppressing the central beam, it is also possible to generate a bidimensional interference pattern which defines an hexagonal structure in the (1 1 1) plane with a period of 377 nm. This optical setup has been used to obtain 3D sub-micrometric periodic structures in negative photoresists. Experiments consist in a one-or multi-pulse irradiation of the photoresist followed by a development procedure which leads to a sub-micrometric face-centred cubic structure cut in a (1 1 1) plane with a cell parameter of 650 nm. The optimization of the experimental conditions is presented for two kinds of photoresists; the role of the substrate according to its reflectivity at the laser wavelength and its influence on the interference pattern is also discussed. #

Domaines: Matériaux

M. Salaun, A.-L Joudrier, M. Audier, S. Pignard. Periodic sub-micrometric structures using a 3D laser interference pattern. Applied Surface Science, 2007, 253 (19), pp.7947-7951. ⟨10.1016/j.apsusc.2007.02.162⟩. ⟨hal-02569537⟩