An arrayed X-ray source and an X-ray imaging apparatus are described. An example X-ray source includes a housing and X-ray generators located in the housing. The X-ray generators are arranged in an array. The X-ray generators are provided separately from each other and configured to emit X-rays independently of each other.

An arrayed X-ray source and an X-ray imaging apparatus are described. An example X-ray source includes a housing and X-ray generators located in the housing. The X-ray generators are arranged in an array. The X-ray generators are provided separately from each other and configured to emit X-rays independently of each other.

An X-ray module includes a housing in which an opening portion is formed; an electron gun that emits an electron beam; a target that transmits an X-ray generated when the electron beam is incident on the target and emits the X-ray from an X-ray-emitting surface; an X-ray-emitting window that seals the opening portion, and that transmits the X-ray and emits the X-ray to a first side in an axial direction; and a heat radiating unit disposed outside the housing. The housing includes a surface on which a protrusion protruding to the first side is formed, the opening portion is formed in the protrusion, and the target is disposed in the opening portion. The heat radiating unit includes a first portion extending along the surface and thermally connected to the surface, and a second portion extending from the first portion to a second side opposite the first side.

An X-ray module includes a housing in which an opening portion is formed; an electron gun that emits an electron beam; a target that transmits an X-ray generated when the electron beam is incident on the target and emits the X-ray from an X-ray-emitting surface; an X-ray-emitting window that seals the opening portion, and that transmits the X-ray and emits the X-ray to a first side in an axial direction; and a heat radiating unit disposed outside the housing. The housing includes a surface on which a protrusion protruding to the first side is formed, the opening portion is formed in the protrusion, and the target is disposed in the opening portion. The heat radiating unit includes a first portion extending along the surface and thermally connected to the surface, and a second portion extending from the first portion to a second side opposite the first side.

Electrons can rebound from an x-ray tube target, causing electrical-charge build-up on an inside of the x-ray tube. The charge build-up can increase voltage gradients inside of the x-ray tube, resulting in arcing failure of the x-ray tube. Also, the electrical charge can build unevenly on internal walls of the x-ray tube, causing an undesirable shift of the electron-beam. An x-ray tube (10 or 20) with multiple protrusions (19) on an interior wall of a drift-tube (18) can reduce this electrical-charge build-up. The protrusions (19) can reflect stray electrons back to the anode target (14), thus suppressing backscatter. Each protrusion (19) can have a peak (19.sub.p) extending into the hole (18.sub.h), and receding to a base (19.sub.b) farther from the electron-beam, on an entry-side (19.sub.en) nearest the drift-tube-entry (18.sub.en) and on an exit-side (19.sub.en) nearest the drift-tube-exit (18.sub.ex).

Methods and systems for realizing a high radiance x-ray source based on a high density electron emitter array are presented herein. The high radiance x-ray source is suitable for high throughput x-ray metrology and inspection in a semiconductor fabrication environment. The high radiance X-ray source includes an array of electron emitters that generate a large electron current focused over a small anode area to generate high radiance X-ray illumination light. In some embodiments, electron current density across the surface of the electron emitter array is at least 0.01 Amperes/mm.sup.2, the electron current is focused onto an anode area with a dimension of maximum extent less than 100 micrometers, and the spacing between emitters is less than 5 micrometers. In another aspect, emitted electrons are accelerated from the array to the anode with a landing energy less than four times the energy of a desired X-ray emission line.

Methods and systems for realizing a high radiance x-ray source based on a high density electron emitter array are presented herein. The high radiance x-ray source is suitable for high throughput x-ray metrology and inspection in a semiconductor fabrication environment. The high radiance X-ray source includes an array of electron emitters that generate a large electron current focused over a small anode area to generate high radiance X-ray illumination light. In some embodiments, electron current density across the surface of the electron emitter array is at least 0.01 Amperes/mm.sup.2, the electron current is focused onto an anode area with a dimension of maximum extent less than 100 micrometers, and the spacing between emitters is less than 5 micrometers. In another aspect, emitted electrons are accelerated from the array to the anode with a landing energy less than four times the energy of a desired X-ray emission line.

An X-ray tube according to the present invention comprises an anode and a cathode comprising an emission portion for emitting an electron beam. The emission portion is configured to irradiate a target surface of the anode with electrons to cause the anode to emit X-rays. A window is arranged at an end of the X-ray tube, to allow X-rays to exit the X-ray tube. The target surface of the anode is inclined at an oblique angle with respect to a longitudinal axis, wherein the longitudinal axis passes through the end of the X-ray tube.

An X-ray tube according to the present invention comprises an anode and a cathode comprising an emission portion for emitting an electron beam. The emission portion is configured to irradiate a target surface of the anode with electrons to cause the anode to emit X-rays. A window is arranged at an end of the X-ray tube, to allow X-rays to exit the X-ray tube. The target surface of the anode is inclined at an oblique angle with respect to a longitudinal axis, wherein the longitudinal axis passes through the end of the X-ray tube.

During operation of a reflection target x-ray source, heat must be removed from many components. The electron beam must be steered to the target and may interact with structures along this path. There is also heat generated in the target itself. This can be excessive, since only a very small percentage of the electron beam's energy is transformed into x-rays. Finally, the x-rays must exit the vacuum through the window, which can also be heated both by the x-rays, reflected electrons, and radiant heat from the target. A water cooled reflective x-ray source provides for water or other fluid cooling of the centering aperture, x-ray target, and/or exit window.