Patterning of Porous Silicon by Electron-Beam Lithography

Electron-beam (E-beam) lithography has been applied to porous silicon substrates. In contrast with optical lithography, the whole process is fully compatible with the material, without any need for particular previous treatments. Porous silicon behaves as a low density substrate, allowing fine writing even at moderate electron energies, with a negligible proximity effect. High quality structures are expected if films deposited on porous silicon are defined by the E-beam, as in the case of freestanding membranes. Patterns written at lower resolution have been successfully transferred to porous silicon using plasma etching techniques. This allows the possibility of direct lateral structuring of porous silicon, a key factor in the realization of high quality devices for photonics.