Electrostatic simulation of a complete cluster deposition apparatus

A complete electrostatic model of a cluster deposition apparatus is presented using SIMION. It consists of fifteen different ion optical components including a quadrupole mass filter and a quadrupole ion deflector. The accuracy of the model was tested by comparing calculated cationic cluster transmissions with experimental ion currents by varying the electrostatic potential of different components. Considering the negatively charged particles produced by the magnetron cluster source as a charged background with a density of 5⋅10^-7 cm^-3, the influence of the first components on cluster transmission is well reproduced in comparison to the experimental results. This background was included by increasing the charge of the clusters from zero to an elementary charge using a sigmoidal function. The inflection point of this function was found to depend on the first components' electrostatic potential but in good approximation, not on later ones. All of the calculated transmissions represent the experimental data quite well; therefore, the simulation is validated and helps us to understand the influence of the electrostatic components on cluster transmission and improve the target efficiency. Furthermore, this understanding opens the possibility for a global optimization scheme to be employed in the ion optics' geometries.