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Biomineralization for lithography and microelectronics

Final Report Summary - BIO-LITHO (Biomineralization for lithography and microelectronics)

The impact of biomineralisation processes on lithographic and microelectronic production processes has not yet been explored. As opposed to conventional industrial manufacturing, the biological synthesis of silica occurs under mild physiological conditions of low temperatures and pressures, with clear advantages in terms of cost-effectiveness, parallel production, and impact on the environment. The integration of nature-mimic biomineralisation processes with micro- and nanofabrication will be a unique route to make them usable in the medium-long term for industrial application and production. In particular, some peculiar proteins of sponges (silicateins) catalyse the reaction of silica polymerisation to give ordered structures. Besides this catalytic activity, when the proteins are assembled into mesoscopic filaments, they serve as scaffolds that spatially direct the synthesis of polysiloxanes over the surface of the protein filaments. Hence, these biomolecules present the combined characteristics of:
(i) chemical action (catalysis) for the formation of silica; and
(ii) patterning action, by driving the silica on the surface of the filaments.
The project planned to exploit this unique combination within a novel technology, whose demonstrator will be the realisation of patterned, aligned assembly of silica fibres, and their employment as insulating layers for prototype transistor devices. Two parallel strategies were pursued for the production of large amounts of silicatein:
(i) expression of the recombinant proteins; and
(ii) development of in vitro primmorph cultures.
Soft lithography techniques will be used for the controlled patterned deposition of molecules. Specific approaches were designed and implemented, for the hierarchical assembly of silicatein fibres into functional networks. The multidisciplinary team involved in the project has the specific know-how in biosilicification / lithography and the intellectual property rights in enzymatic silica formation.

In this project, nature was used as a model for the structure-directed synthesis of amorphous silica (biosilica). Usually the synthesis of glass-like silica structures requires high temperature or high pressure processes limiting the possibility to built up functional biomolecule-silica composite structures. The new enzymes (silicateins patented by the consortium) allow the controlled formation of silica patterns on surfaces and the construction of specifically designed nanostructures.

The project exploits the unique ability of siliceous sponges to synthesise their skeleton enzymatically. The described bionic approaches are of enormous commercial importance in view of their application in nanobiotechnology. The realised FET devices could be competitive candidates for existing and novel applications that require large area coverage, structural flexibility, and especially low temperature processing and low fabrication costs. In the framework of large-scale manufacturing, there is currently a strong demand for inexpensive deposition and patterning processes that can be easily incorporated within existing device concepts.

A number of measures has been undertaken to disseminate the results of the project to the public. These activities did not only include contributions to conferences or workshops but also contributions to exhibitions / fairs or the distribution of information of material to potential customers by the industrial partners involved in this project.

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