Leland Stanford Junior University

Intevac, Inc.

Aaron W Baum

Kenneth A Costello

R Fabian Pease

Mark A McCord

James E Schneider

James Edward Schneider, Jr

An electron beam microscope includes an electron beam pattern source, a vacuum enclosure, electron optics, a detector and a processor. The electron beam pattern source generates a sequence of electron beam patterns for illuminating a set of pixels on a specimen. The electron optics directs the sequence of electron beam patterns to the specimen. The detector detects a result of an interaction between each of the electron beam patterns and the specimen and produces a sequence of detector signals. The processor, in response to the sequence of detector signals, generates an image including a pixel value representative of each of the illuminated of pixels on the specimen. The electron beam microscope preferably includes a deflector for deflecting each of the electron beam patterns relative to the specimen.

Electron beam microscope using electron beam patterns

An electron source includes a negative electron affinity photocathode on a light-transmissive substrate and a light beam generator for directing a light beam through the substrate at the photocathode for exciting electrons into the conduction band. The photocathode has at least one active area for emission of electrons with dimensions of less than about two micrometers. The electron source further includes electron optics for forming the electrons into an electron beam and a vacuum enclosure for maintaining the photocathode at high vacuum. The photocathode is patterned to define emission areas. A patterned mask may be located on the emission surface of the active layer, may be buried within the active layer or may be located between the active layer and the substrate.

Electron sources utilizing patterned negative electron affinity

An electron beam source includes a cathode having an electron emission surface including an active area for emission of electrons and a cathode shield assembly including a conductive shield disposed in proximity to the electron emission surface of the cathode. The shield has an opening aligned with the active area. The electron beam source further includes a device for stimulating emission of electrons from the active area of the cathode, electron optics for forming the electrons into an electron beam and a vacuum enclosure for maintaining the cathode at high vacuum. The cathode may be a negative electron affinity photocathode formed on a light-transmissive substrate. The shield protects non-emitting areas of the emission surface from contamination and inhibits cathode materials from contaminating components of the electron beam source. The cathode may be moved relative to the opening in the shield so as to align an new active area with the opening. Getter materials and sources of activation material may be incorporated into the shield assembly.

Electron sources having shielded cathodes

An electron source includes a negative electron affinity photocathode on a light-transmissive substrate and a light beam generator for directing a light beam through the substrate at the photocathode for exciting electrons into the conduction band. The photocathode has at least one active area for emission of electrons with dimensions of less than about two micrometers. The electron source further includes electron optics for forming the electrons into an electron beam and a vacuum enclosure for maintaining the photocathode at high vacuum. In one embodiment, the active emission area of the photocathode is defined by the light beam that is incident on the photocathode. In another embodiment, the active emission area of the photocathode is predefined by surface modification of the photocathode. The source provides very high brightness from an ultra-small active emission area of the photocathode.

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San Francisco, CA, United States of America

Aaron W Baum