**5. Conclusion**

254 Recent Advances in Nanofabrication Techniques and Applications

In order to obtain inorganic nanostructures, sol-gel-based spin-coatable precursor of ZrO2 that is not only amenable to direct-write using DUV lithography but is also capable of

The crosslinking photoreaction relies on a direct photolysis of the complexed Zr atom. The interaction between UV light and metal alkoxide complex has been already described : after light absorption, charge transfer complexes can be created and they can induce a photolysis of the ligand (Versace et al., 2008). For Titanium alkoxides, it has been proved that Ti-oxo complex gave rise to a decarboxylation reaction (Hundiecker reaction (Soppera et al., 2001)). In the present case, we can assume that the same kind of mechanism occurs, leading to the production of reactive Zr species that can react on free alkoxides functions to create a

> iPrO M OiPr O O

> > M O O

O M OiPr O O

**193 nm**

O O

M O

DUV-irradiation Photolysis of the complex

M

OiPr

M

M O

O O O

O O O iPrO M OiPr

O O

H2O

M O

M O

M O M O M O

iPrO OiPr

O O O O O O O O

O O

iPrO M O O O

O O

iPrO M O O M O

O O O O O O O O

O

Fig. 9. Schematic representation of the material preparation and modification under DUV irradiation of the negative tone inorganic resist. M is a transition metal (Zr, Ti…). As shown in this scheme, the DUV irradiation results in condensation of the partially condensed metal alkoxide precursors resulting in a modification of solubility of the thin film (Ridaoui et al.,

The main interest of this negative tone resist relies on the possibility to remove the organic part and obtain ZrO2 after thermal treatment. The AFM scan of the sample is plotted in Figure 10. It can be observed that the patterns remained perfectly defined after the thermal treatment, opening a very convenient way to produce micro or nanostructures. Applications of such nanostructures with high refractive index are expected in the field of optics and photonics. Many applications of such technology are also expected in all applications fields in which robust nanostructures with inertness towards chemical, temperature, and pressure

**4.2 Nanopatterning of hybrid precursors by DUV interferometry** 

providing nanoscale resolution was proposed. (Ridaoui et al., 2010)

iPrO M OiPr OiPr

> **SOLUBLE RESIN**

**UNSOLUBLE RESIN**

are needed such as photovoltaic, photocatalysis or biology.

OiPr

OH O

tridimensional ZrO2 network (Figure 9).

2010)

The development of large-area, high-resolution nanostructures is a challenging problem that must be addressed for applications in high performance nanoscale devices, such as nanoelectronics, optics, microfluidics, organic solar cell, display devices and biosensing devices. Today's challenges are not limited to the resolution issue but many others aspects are to be considered. In particular, there is a growing need for simple processes enabling integration of functional materials.

With this regards, DUV interferometric lithography techniques are still of high interest, as illustrated in this chapter. The recourse to advanced optical setup and immersion allow creating patterns with typical dimensions much smaller than 100 nm on the basis of many different materials. This photon-based technique is thus competitive in terms of resolution with other advanced nanofabrication techniques and because it is a massively parallel technology to produce nanoparts on a large substrate, it is well-complementary to e-beam, ion-beam or nanoimprint.
