For several decades, Gallium (Ga+) remained an ion species of choice for circuit edit (CE) applications due to its excellent micro and nanomachining capabilities. But due to continuous device scaling, now it is becoming highly challenging to fulfill all the needs of CE with Ga+ based focused ion beam (FIB) tools. Recently Neon gas field ionization source (GFIS) has emerged as one of the most viable solutions to supplement CE requirements where a Ga+ FIB falls behind [1]. A lot of effort has gone into the beam characterization of the Neon (Ne+) and Helium (He+) beams of Orion NanoFab that is the first GFIS based commercial tool. In this paper, we present our results on resolution characterization of He+ and Ne+ beams as a function of beam energy.

He+ beam resolution characterization was done at 10, 20 and 30 kV beam energies whereas Ne+ beam resolution was characterized at 10 and 25 kV. The test was conducted on CVD graphene on TEM grid and ImageJ was used for image analysis. The lateral resolution for Helium was 0.54 ± 0.07 nm at 30 kV beam energy whereas for Neon the resolution was 2.45 ± 0.46 nm at 25 kV beam energy both with 100 fA beam currents. The unparalleled resolution specs. of Ne+ and He+ ion beams have made them attractive not only for CE but for many other applications like high resolution imaging for fault isolation, failure analysis, EUV mask repair, lithography, graphene pattering, plasmonics and biological imaging etc. [2].

Reference:

1. S. Tan and R. Livengood “Applications of GFIS in semiconductors”, book chapter, Helium Ion Microscope, pp 471-498, Springer (2016).

2. J. Orloff, "Fundamental limits to imaging resolution for focused ion beams", Journal of Vacuum Science and Technology B, vol. 14, pp. 3759 (1996).