The application of energetic CHx+ ions to form a Si/SiC multilayer systems for reflection of radiation between 20 and 80 nm
Implantation of CHx+ ions with an energy of 1 keV into Si as well as deposition of Si assisted by bombardment with 500 eV CHx+ ions (Ion Beam Assisted Deposition (IBAD)) were applied to form Si/SiC multilayers. For deposition, e-beam evaporation was used, while a Kaufman broad-beam ion source was available for ion bombardment. After deposition of a Si layer and subsequent ion bombardment, Auger Electron Spectroscopy combined with sputter etching was used to achieve a depth profile of the carbon content. As expected a graded mixture of carbon and silicon was observed to an implantation depth that scaled with the ion energy. However, from the shift of the Si LMM Auger peak it became clear that for 500 eV ions carbide was only formed near the surface, while for 1 keV the maximum carbide concentration appeared at a depth of around 2 nm. In order to demonstrate the feasibility of the implantation as well as the IBAD process, multilayers with a periodicity of 10.8 nm were grown. The structures were characterized by ?:2? Cu Ka reflectometry. As the optical contrast between Si and C can be neglected compared to the contrast between Si and SiC, this technique revealed for both multilayer production processes the formation of a periodic Si/SiC structure. A preliminary fitting procedure with the measured Cu Ka reflectometry curves confirmed that the system produced by implantation with 1 keV ions contains a carbide layer localized within 0.6 nm. In the IBAD deposited system an amount of 25% carbide is distributed over a layer thickness of ˜5 nm as a part of a mixture with C and Si. This results in a lower contrast than for the implanted system.
|Journal||Nucl. Instrum. Methods Phys. Res. B|
Dobrovolskiy, S, Yakshin, A. E, Kessels, M. J. H, & Verhoeven, J. (2005). The application of energetic CHx+ ions to form a Si/SiC multilayer systems for reflection of radiation between 20 and 80 nm. Nucl. Instrum. Methods Phys. Res. B, 237, 533–542. doi:10.1016/j.nimb.2005.03.285