New high resolution scanning ion microprobe and focused ion beam applications

The University of Chicago and Hughes Research Laboratories have successfully completed a four-year collaborative program for the development and construction of two 60 kV high-resolution, high current density ion-microscopes/microprobes. Performance evaluation tests with a liquid gallium ion source have thus far demonstrated focused spot diameters of 90 and 45 nanometers, excellent imaging capacity using ion-induced secondary electrons and ion signals, and unusual performance of a high-transmission secondary ion mass spectrometry system. Concurrently with the new microprobe development, previously existing prototype scanning ion microscope have been employed in fundamental studies of ion-solid interactions and contrast mechanisms in ion microscopy, where ion-channeling effects in crystalline materials yield images exhibiting extraordinary crystallographic contrast. Exploratory research applications of the new microprobes comprise elemental mapping at high spatial resolution (50 nm) of microelectronic structures and devices in gallium arsenide, studies of the elemental composition and mineral distribution in stony meteorites (chondrites), with emphasis on the analysis of the rims of primordial aggregate bodies (chondrules), the detection of staging domains in antimony pentachloride-intercalated graphites, elemental mapping in minerals of biological origin, in particular the detection the onset of calcification in bone tissues, and various approaches to focused ion beam microfabrication and microlithography, where structures with 100 nm linewidth have been demonstrated.