Magnetic lens apparatus for a low-voltage high-resolution electron microscope
AssigneeArch Development Corporation
InventorAlbert V. Crewe
Life of this patent
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Abstract
A lens apparatus in which a beam of charged particles of low accelerating voltage is brought to a focus by a magnetic field, the lens being situated behind the target position. The lens comprises an electrically-conducting coil arranged around the axis of the beam and a magnetic pole piece extending along the axis of the beam at least within the space surrounded by the coil. The lens apparatus comprises the sole focusing lens for high-resolution imaging in a low-voltage scanning electron microscope.
Claims45
A lens apparatus adapted for use in a device for focusing a beam of charged particles, comprising:
- (a) a solid pole piece for focusing a beam of charged particles having an accelerating voltage of about 100 to about 10,000 V;
- and
- (b) an electrically-conducting coil coiled around said pole piece for energizing said pole piece to produce a magnetic field, wherein said pole piece and coil are positioned within a yoke.
A method for focusing a beam of charged particles having an accelerating voltage of between about 100 and about 10,000 V, said method comprising:
- (a) providing a source of charged particles having an accelerating voltage of about 100 to about 10,000 V along a given axis;
- and
- (b) focusing said beam with a magnetic field produced by a lens apparatus comprising a solid pole piece for focusing a beam of charged particles having an accelerating voltage of about 100 to about 10,000 V;
- and an electrically-conducting coil coiled around said pole piece for energizing said pole piece to produce a magnetic field, wherein aid pole piece and coil are positioned within a yoke.
A lens apparatus adapted for use in a device for focusing a beam of charged particles, comprising:
- (a) a solid pole piece for focusing a beam of charged particles having an accelerating voltage of from about 100 to about 10,000 V;
- and
- (b) an electrically-conducting coil coiled around said pole piece for energizing said pole piece to produce a magnetic field, wherein said pole piece and coil are positioned within a yoke, said magnetic field sufficient for resolving said beam of charged particles to a resolution less than about 4 mm at an accelerating voltage of about 1000 V.
A lens apparatus adapted for use in a device for focusing a beam of charged particles, comprising:
- (a) a solid pole piece for focusing a beam of charged particles having an accelerating voltage of from about 100 to about 10,000 V, said pole piece capable of producing a field strength of from about 2 to about 4 Tesla;
- and
- (b) an electrically-conducting coil coiled around said pole piece for energizing said pole piece to produce a magnetic field, wherein said pole piece and coil are positioned within a yoke, said magnetic field sufficient for resolving said beam charged particles to a resolution less than about 4 mm at an accelerating voltage of about 1000 V.
Dependencies are inferred from the claim text.