Focused ion beam microfabrication column

Claim 1

A mass separated, focused ion beam microfabrication system for forming a high resolution, direct-write ion beam having a small spot size and high current density at a target, comprising: a high intensity, substantially point source of a desired species of ions, means for extracting an angularly expanding ion beam from the source at an initial energy leval which is low compared to the final beam energy, a low aberration focusing means positioned to focus the beam to a crossover without substantially increasing the beam energy, a mass separator positioned in the beam path between the focusing means and the beam crossover to deflect undesired ion species out of the beam path, the mass separator operating with relatively weak fields corresponding to the relatively low initial beam energy, and thereby imparting little aberration to the beam, an energy control means comprising a pair of spaced electrodes positioned in the vicinity of the beam crossover for accelerating the beam ions to an intermediate energy level without substantially changing the beam focus, the energy control means thereby avoiding any substantial increase in beam aberration. an electrostatic focus/accelerating means comprising a pair of spaced electrodes positioned in the beam path beyond the crossover, a variable power supply means connected to apply respective voltage differentials across the energy control and focus/accelerating electrodes sufficient to focus the beam to a small spot with a high current density and to establish the energy of the beam emerging from the energy control meas, relative to the ion source, at a substantially constant fraction of the beam energy emerging from the focus/accelerating means, and at a changing fraction of the beam energy emerging from the extraction means as the power supply is varied, and means for deflecting the spot over a target in a desired manner to implant a desired ion pattern on the target.

Claim 5

A method of forming a high resolution, focused ion beam having a small spot size and a high current density at a target for direct-write microfabrication, comprising the steps of: forming an angularly expanding beam of a desired ion species at an initial relatively low energy level, focusing the beam to a crossover without substantially increasing its energy, means separating the beam with relatively weak fields to deflect undesired ion species out of the beam path, accelerating the mass separated beam in the vicinity of the beam crossover to an intermediate energy level without substantially changing the beam focus, electrostatically focusing and accelerating the beam beyond the crossover to a small spot with a high current density, varying the intermediate beam energy level as a substantially constant fraction of the final beam energy and as a changing fraction of the initial beam energy, and deflecting the spot over a target to implant a desired ion pattern on the target.

Claim 6

A method of forming a high resolution, focused ion beam having a small spot size and a high current density at a target for direct-write microfabrication, comprising the steps of: forming an angularly expanding beam of a desired ion species at an initial relatively low energy level, focusing the beam to a crossover without substantially increasing its energy, means separating the beam with relatively weak fields to deflect undesired ion species out of the beam path, accelerating the mass separated beam in the vicinity of the beam crossover to an intermediate energy level without substantially changing the beam focus, electrostatically focusing and accelerating the beam beyond the crossover to a small spot with a high current density, varying the intermediate beam energy level as a substantially constant fraction of the final beam energy and as a changing fraction of the initial beam energy, and deflecting the spot over a target to implant a desired ion pattern on the target.