Noel Smith

High brightness inductively coupled plasma source for high current focused ion beam applications

A high brightness plasma ion source has been developed to address focused ion beam (FIB) applications not satisfied by the liquid metal ion source (LMIS) based FIB. The plasma FIB described here is capable of satisfying applications requiring high mill rates (>100μm3∕s) with non-gallium ions and has demonstrated imaging capabilities with sub- 100-nm resolution. The virtual source size, angular intensity, mass spectra, and energy spread of the source have been determined with argon and xenon. This magnetically enhanced, inductively coupled plasma source has exhibited a reduced brightness (βr) of 5.4×103Am−2sr−1V−1, with a full width half maximum axial energy spread (ΔE) of 10eV when operated with argon. With xenon, βr=9.1×103Am−2sr−1V−1 and ΔE=7eV. With these source parameters, an optical column with sufficient demagnification is capable of forming a sub-25-nm spot size at 30keV and 1pA. The angular intensity of this source is nominally three orders of magnitude greater than a LMIS making the source more a...

The Hyperion™ Ion Probe for Next Generation FIB, SIMS and Nano-Ion, Implantation

Am -2 sr -1 V -1 with oxygen and 2.7x10 3 Acm -2 sr -1 with hydrogen. Unlike point ion sources (eg the liquid-metal ion source), the effective beam brightness at the target can be maintained from picoAmps up to many micro-Amps. The combination of high brightness, low energy spread and very high angular intensity provides this broad range of operating currents. A comparison of the typical gallium FIB performance with the Hyperion TM FIB is shown in figure 1. Hyperion TM excels at beam currents >50nA, while still having the brightness to provide <25nm resolution for imaging at 30keV.

High voltage breakdown in an inductively coupled ion source

An inductively coupled plasma source, designed for ion beam applications, is allowed to float up to several kilovolt positive. If one side of the radio frequency (rf) antenna is grounded and the dielectric source tube and the surrounding air are allowed to reach a threshold temperature corona breakdown at the rf antenna occurs. The experiments presented here show that a dc corona can be ignited with the presence of a dielectric barrier, which normally precludes dc breakdown. The formation of a negative barrier corona initiates a transition to a continuous arc from the rf antenna to the source tube. It is suggested that the onset of the first filaments heat the dielectric locally, such that the dielectric strength drops. DC current channels are then formed in the source tube, allowing a resistive corona with continuous arcs to exist.