Gas delivery and virtual process chamber concept for gas-assisted material processing in a focused ion beam system

Abstract

Gas-assisted etching and material deposition using gaseous precursors have become a critical part of integrated circuit modification and other applications of focused ion beam (FIB) systems. Widely used methods of gas injection in FIB systems are either needle-type or shroud-type gas delivery nozzles. Each of these methods of gas delivery has significant drawbacks. Release of the gas from the needle-type nozzles is detrimental for the vacuum level in the main chamber of the system, as the gas quickly dissipates from the process area. Insertion of shroud concentrators into the primary ion beam path and the path of secondary electrons leads to a significant decline in the signal-to-noise ratio of the FIB image. Proposed “CUPOLA” geometry of the gas delivery nozzle could allow one to effectively concentrate process gas in the area of interest, as is currently done by shroud concentrators, and, according to secondary-electron trajectory simulations, would significantly improve the signal level of the secondary-electron image, as compared to the shroud concentrators.