Processing of Sol-Gel Films from a Top-Down Route

The deposition of films from a liquid phase whose precursor solution has been synthesized via sol-gel chemistry has widely been applied to produce coatings of different compositions and structures, such as oxides, hybrids, nanocomposites, and mesoporous coatings. Chemical-physical methods, such as plasma-enhanced chemical vapor deposition (PECVD) or chemical vapor deposition (CVD), are still fevored for most of the industrial applications. The sol-gel route to films, however, even if has not been able to challenge these techniques in terms of mass production, has occupied an important niche in the field. 

The Sol-Gel Handbook Synthesis, Characterization, and Applications, First Edition. 

Many examples of top-down processes applied to as-deposited sol-gel films have been reported so far in the literature, and several of them have been used for industrial processing. Sol-gel coatings include a very large family of different materials, such as oxides, organic-inoiganic hybrids, and nanocomposites, and the right process has to be modulated case by case. 

Soft X-ray lithography has also been widely used for patterning sol-gel films [16] a possible alternative method is the exposure to hard X-rays that are characterized by a higher energy. 

In general, a top-down approach is based on light-matter interaction, which in case of materials in the soft state is particularly effective because of the low degree of condensation and the presence of organic compounds. The radiation-induced changes are produced via the reactive species that are created by the fight irradiation. The effect very much depends on the energy and brilliance of the source the choice of the best technique depends not only on the properties that the material should exhibit, but also on the availability of the source and the cost and time required for the process. 

---

Processing of Sol-Gel Films from a Top-Down Route References... 

---