TiO2 patterning using electro-hydrodynamic lithography.

An increasing number of technologies require the fabrication of micro- and nanostructures over large areas. Soft lithographic methods are gaining in popularity for the manufacture of low-cost micrometre and sub-micrometre structures. Increasingly, these methods developed to structure organic resists can also be used to pattern inorganic materials. Here we introduce a simple lithographic technique that is able to pattern ceramic TiO micro- and nanostructures with high fidelity. Our method makes use of an electrohydrodynamic (EHD) film instability that is controlled by a laterally modulated electric field. A spin-coated film of a stabilized metal alkoxide precursor material was patterned using EHD lithography followed by a heat treatment at 400 °C to yield crystalline TiO micropatterns. Our technique is rather general and can be extended to a number of single- and multicomponent oxide systems.

Pattern formation by temperature-gradient driven film instabilities in laterally confined geometries.

Film break-up driven by an electric field or temperature gradient typically exhibit a characteristic length scale. The presence of a lateral confinement significantly alters this pattern formation process.

Hierarchical structure formation and pattern replication induced by an electric field.

Several techniques based on soft lithography have emerged to replicate micrometre-sized patterns. Similar to most other lithographic methods, these techniques structure a single layer of photo resist. For many applications, however, it is desirable to control the spatial arrangement of more than one component. With traditional methods, this requires an iterative, multistep procedure, making the replication process more complex and less reliable. Here, a replication process is described where multiple materials are processed simultaneously. Using a bilayer formed by two different polymers, electrohydrodynamic instabilities at both polymer surfaces produce a hierarchic lateral structure that exhibits two independent characteristic dimensions. A lateral modulation of the electric field enables replication with a resolution down to 100 nanometres. This approach might provide a simple strategy for large-area, sub-100-nanometre lithography.