Evaluation of a Neon Focused Field Ion Source: Fabrication and Characteristics
A new type of gaseous field ion source, operated with the inert gas neon, was developed. The source material used was the equiatomic B 2-ordered Ni-Al alloy doped with small amounts of W and C. Small surface protrusions were formed by the field evaporation of the multiphase alloy containing ultrafine spherical precipitates. The emission current-voltage characteristics were recorded as a function of neon gas pressure and source temperature. Total source current densities of up to 6 nA were obtained. A source temperature just above the condensation point of Ne gas was found to generate the highest ion current
A novel approach to gaseous field ion sources for focused ion beam applications
Abstract Experiments have demonstrated that significantly increased angular current densities may be obtained from protrusions formed from ultrafine precipitates compared to the normal field ion specimens. The confinement of the ion-emitting region to the precipitates is an effective method of increasing the angular current density. This type of emitter may be a potential candidate for gaseous focused ion sources.
Energy spreading in the hydrogen field ionization source
The application of field ionization as a tool for routine submicron fabrication will depend critically upon the characteristics of the source; the angular intensity and the energy spread of the ions. The chromatic aberration coefficient of the ion optical system, the angular aperture, and the energy spread combine to set the limit of spot size and current density for very‐high‐resolution probes with sources of energy widths even as low as 1 eV. It is known that the various molecular species produced by hydrogen field ionization are indentifiable by the energy distribution, and because the mass of the ion will determine the particle range in resists at any given energy, energy measurements carry further importance in the development of the probe‐forming system. In order to characterize the source‐energy widths and mass species as a function of beam current, angular intensity, and surface characteristics of the emitter tip, we have designed and operated a unitized, positionable intermediate image filter len...