High-purity cobalt nanostructures grown by focused-electron-beam-induced deposition at low current

Abstract

Focused-electron-beam-induced deposition (FEBID) allows the creation of three-dimensional nanostructures of different materials using the appropriate precursor material. The fabrication of magnetic nanopatterns by means of this direct-write technique is an interesting alternative to more conventional lithographic methods. In the present work, we explore the use of the FEBID technique to grow Co nanostructures with high-purity (>90% at.) using dicobalt octacarbonyl [Co 2(CO) 8] and with low beam currents (pA range), thus guaranteeing the high lateral resolution of the nanodeposits. It is found that under such low beam currents, the Co content can be greatly enhanced if the substrate temperature is increased at ∼100 °C by means of a micro-hotplate. The occurrence of thermal decomposition of the precursor molecules in contact with the micro-hotplate has been observed at ∼200 °C. These results also demonstrate the important role played by local heating effects in the Co content attained in the deposits.