Déformation photoinduite dans les films minces contenant des ...

Chapter 5. Nanostructured hybrid systems 142(1)DR1-filmopticalnanostructuration(2)evaporationin grazingincidence(2’)goldshadowmaskpastel-00527388, version 1 - 19 Oct 2010Figure 5.4: Large scale patterning process of gold coated PMMA-DR1. From leftto right: (1) optical nanostructuration of a PMMA-DR1 sample under p-polarizedinterfering beams, laser (blue, λ = 473 nm) power density: 1 mW/mm 2 per beam,incidence angle = 16.5 ◦ , spatial period ≃ 830 nm; (2) evaporation of a 40 nm thickgold layer in grazing incidence in order to obtain a deposition only on the sides of thenanostructured periodic pattern, which constitutes (2’) a gold shadow-mask.5.2 Hybrid optically nano-structured organized surfacesIn section 4.1 we have shown that the optical patterning of hybrid metal/azo-polymerlayered structures can be achieved, exploiting the photodeformation capabilities of theunderlying photochromic material. Here (3) we will present some preliminary results demonstratingthe possibility to elaborateopticalmore complex large scale nano-structured systems.over-patterning5.2.1 Complex structures5.2.1.1 Grid fabricationIn Figure 5.4 we show a simple two-step process that allows to obtain a metallic stripearray on an azo-polymer film, which is shown in Figure 5.5. In step (1) we inducea periodic photodeformation on a PMMA-DR1 thin film by means of two polarizedinterfering beams (1 mW/mm 2 per beam), using the same experimental setup as inthe previous section. For a film thickness of 200 nm the typical relief height is 80 nm.Then (step 2) we grow a gold shadow mask, having a thickness of approximately 40 nm,by evaporation in grazing incidence. In this way (2’) we obtain a gold deposition onlyon one side of the periodic reliefs previously inscribed. SEM images of the obtainedgold stripe array are reported in Figure 5.5(a), while in Figure 5.5(b) we show thetopography measurement performed by shear-force microscopy. We observe that the