Monday, June 18, 2007
Golden Eagle Eyrie (Boise Centre on the Grove)

SIMION Guided Ion Sampling

Jeffrey Mottishaw, Idaho State University, Pocatello, ID and René Rodriguez, Idaho State University, Pocatello, ID.

SIMION, an ion simulation program, was used to test out several geometries in an effort to optimize the ion optics used to sample ions from an rf-plasma reactor for subsequent mass analysis by quadrupole mass spectrometery. The ability to sample ions directly from the plasma offers significant information toward an accurate overall picture of plasma etching and deposition processes. We seek to modify the current design to attain better readings at low concentrations of ionic species. Modeling with SIMION suggests that enhanced extraction and MS analysis is possible using two sets of lenses (the second set being factory from Extrel™ and all lenses being Einzel-like). The use of relatively low voltages on the lens components, assuming that the starting kinetic energy of the ions was in the 4-5eV range, appears to aid in the focusing of the ions. It is possible that higher voltages on the lens components in the previous setup may have lead to ions slamming against the plates and never reaching the quadropoles. Theoretical and preliminary experimental results based upon the new SIMION derived geometry will be presented.