T. Willemsen
M. Jupé
S. Malobabic
K. Schuba
D. Ristau

Modeling and Experimental Studies in an Advanced Filtered IBS Process

Magnetron, Ion Processing & Arc Technologies European Conference & International Symposium on Reactive Sputter Deposition (MIATEC-RSD)
8.-11. Dezember
Type: Konferenzbeitrag
In order to fulfill the rising demands of industrial applications, optical devices are necessary characterized by losses, which are often correlated to low particle contaminations and scattering levels. Especially, highly developed sputtering techniques like Ion Beam Sputtering (IBS) are able to manufacture dielectric optics of total loss levels in the range of few ppm. However, the inclusion of particles during the sputtering process impedes significant improvements. Novel high quality deposition techniques are necessary for excluding particle contaminations, which is linked to a detailed understanding of the processes in the plasma. Regarding to the requirements of future high end optical components, filtered sputtering techniques seem to be a promising approach. Hereby, the interaction of the sputtered plasma with electro-magnetic fields requires a precise knowledge of the field matter interaction. In the present contribution an IBS process is combined with a field separator, based on a magnetic coil system. This novel set-up is expected to achieve the requirements of the next generation of optical components. Applying a well-controlled plasma guiding, a separation of the sputtering process and the layer deposition is realized by two separated chambers. It has to be mentioned that the degree of ionization is significant higher as in a common IBS process, and therefore the influence of neutral material can be neglected. Thereby, macro particles and neutrals are filtered out of the plasma beam and the particle density on the substrate is minimized. In order to achieve an economic process, an optimization of the guiding efficiency is necessary. Consequently, the influence of the electro- magnetic field on the plasma guiding has been simulated according to Lagrange formalism. The electro static potential for the simulation was excluded applying Langmuir probe experiments. Additionally, the kinetic energy of the ions is measured by using a retarding field analyzer. The measurements of the plasma properties are completed by deposition experiments, which are performed at the exit of the linear transfer coil and at the exit of the bent separation coil, respectively. Especially, the results of the deposition experiments behind the linear transfer coil are correlated with the theoretical studies, whereas a high agreement was demonstrated. Further on the results are used to manufacture a high reflector using a fixed content of a ternary composition by tuning the magnetic field. Additionally, the resulting particle contaminations of test samples were compared to dielectric components manufactured by common IBS processes. Hereby a significant improvement was demonstrated according to the scattering level of the optical devices.