Charged particle source with integrated energy filter
First Claim
1. Charged particle source for producing a beam of charged particles, comprisinga charged particle emitting surface emitting charged particles,a lens for forming an image of the charged particle emitting surface, said lens having an optical axisa beam limiting diaphragm for limiting of the beam, embodied in such a way that at least two beams are formed, a central beam going through the middle of the lens and an eccentric beam going eccentrically through the lens,a first deflector embodied to deflect one of the beams towards the axis, andan energy selecting diaphragm showing an energy selecting aperture for passing a part of the eccentric beam and a central aperture for passing the central beam, said energy selecting diaphragm positioned between the particle emitting surface and the deflector, anda second deflector to align the eccentric beam on the energy selecting aperture, the source configured such thatwhen the eccentric beam is focused and aligned on the energy selecting aperture using the second deflector, the second deflector simultaneously deflects the central beam to such an extent that the central beam is blocked by the energy selecting diaphragm.
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Accused Products
Abstract
The invention describes a particle source in which energy selection occurs. The energy selection occurs by sending a beam of electrically charged particles 103 eccentrically through a lens 107. As a result of this, energy dispersion will occur in an image formed by the lens. By projecting this image onto a slit 109 in an energy selecting diaphragm 108, it is possible to allow only particles in a limited portion of the energy spectrum to pass. Consequently, the passed beam 113 will have a reduced energy spread. Deflection unit 112 deflects the beam to the optical axis 101. One can also elect to deflect a beam 105 going through the middle of the lens toward the optical axis and having, for example, greater current.
The energy dispersed spot is imaged on the slit by a deflector 111. When positioning the energy dispersed spot on the slit, central beam 105 is deflected from the axis to such an extent that it is stopped by the energy selecting diaphragm. Hereby reflections and contamination resulting from this beam in the region after the diaphragm are avoided. Also electron-electron interaction resulting from the electrons from the central beam interacting with the energy filtered beam in the area of deflector 112 is avoided.
31 Citations
17 Claims
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1. Charged particle source for producing a beam of charged particles, comprising
a charged particle emitting surface emitting charged particles, a lens for forming an image of the charged particle emitting surface, said lens having an optical axis a beam limiting diaphragm for limiting of the beam, embodied in such a way that at least two beams are formed, a central beam going through the middle of the lens and an eccentric beam going eccentrically through the lens, a first deflector embodied to deflect one of the beams towards the axis, and an energy selecting diaphragm showing an energy selecting aperture for passing a part of the eccentric beam and a central aperture for passing the central beam, said energy selecting diaphragm positioned between the particle emitting surface and the deflector, and a second deflector to align the eccentric beam on the energy selecting aperture, the source configured such that when the eccentric beam is focused and aligned on the energy selecting aperture using the second deflector, the second deflector simultaneously deflects the central beam to such an extent that the central beam is blocked by the energy selecting diaphragm.
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13. Charged particle source for producing a beam of charged particles, comprising
a charged particle emitter; -
a lens for focusing the charged particles emitted by the emitter into a beam, said lens having an optical axis; multiple first apertures for producing at least two beams including, a central beam passing through the center of the lens and at least one eccentric beam passing through the lens away from its center; a deflector for selecting either the central beam or one of the eccentric beams to pass through a corresponding aperture and out of the charged particle source, the beams not selected being blocked so that a single beam leaves the charged particle source. - View Dependent Claims (14, 15, 16, 17)
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Specification