X-ray surface analysis and measurement apparatus

Patent metadata

Field	Value
Publication number	US-9823203-B2
Application number	US-201615060477-A
Country	US
Kind code	B2
Filing date	Mar 3, 2016
Priority date	Feb 28, 2014
Publication date	Nov 21, 2017
Grant date	Nov 21, 2017

Abstract

Systems for x-ray diffraction/scattering measurements having greater x-ray flux and x-ray flux density are disclosed. These are useful for applications such as material structural analysis and crystallography. The higher flux is achieved by using designs for x-ray targets comprising a number of microstructures of one or more selected x-ray generating materials fabricated in close thermal contact with a substrate having high thermal conductivity. This allows for bombardment of the targets with higher electron density or higher energy electrons, which leads to greater x-ray flux. The high brightness/high flux source may then be coupled to an x-ray reflecting optical system, which can focus the high flux x-rays to a spots that can be as small as one micron, leading to high flux density, and used to illuminate materials for the analysis based on their scattering/diffractive effects.

First claim

We claim:

1. An x-ray system for analyzing a specimen, comprising:
at least one x-ray source comprising:
a vacuum chamber;
a window transparent to x-rays attached to the wall of the vacuum chamber;
and, within the vacuum chamber:
at least one electron beam emitter, and
an anode target comprising:
a substrate comprising a first selected material, and
a planar first surface, from which thickness is measured in a direction perpendicular to the first planar surface, and
two orthogonal lateral dimensions are measured parallel to the first planar surface; and

a plurality of discrete structures embedded into the first planar surface of the substrate such that each of the plurality of discrete structures is in thermal contact with the substrate,
the plurality of discrete structures comprising:
one or more materials selected for its x-ray generation properties;

in which at least two of the plurality of discrete structures are arranged on a predetermined axis;
in which the axis is parallel to the first planar surface of the substrate;
in which the axis passes through the first window;
in which each of the discrete structures has a thickness of less than 20 microns, and
in which each of the plurality of discrete structures has a lateral dimension in the direction of the axis of less than 50 microns; and

a means of directing electrons emitted by the at least one electron beam emitter onto the at least two arranged discrete structures such that x-rays are generated from each of the at least two arranged discrete structures;
in which at least a portion of the generated x-rays propagating on the predetermined axis from each of the at least two arranged discrete structures is transmitted through the window;
and additionally comprising:
an x-ray optical system having an optical axis aligned relative to said predetermined axis,
said optical system positioned to collect diverging x-rays accumulated from said at least two arranged discrete structures in the x-ray source and to condition and create an x-ray beam with predetermined properties;
said optical system additionally comprising a central beam stop positioned to block x-rays propagating parallel to the optical axis;
an adjustable means to direct the x-ray beam to be incident on the specimen with an adjustable grazing angle smaller than the critical angle of the specimen;
at least one detector which detects the intensity of the x-rays emerging from the specimen and generates electrical signals; and
a signal processor to analyze the electrical signals to obtain information about at least one of:
composition, concentration, quantity, and film thickness.

2. The x-ray system of claim 1 ,
in which said at least one detector is positioned to detect x-rays that are diffracted by the specimen;
and additionally positioned such that a portion of the detector also detects x-rays reflected from the surface of the specimen.

3. The x-ray system of claim 1 , in which
said predetermined axis and said optical axis are coincident.

4. The x-ray system of claim 1 , in which
said optical system comprises a total external reflection based x-ray optic.

5. The x-ray system of claim 1 , in which
said x-ray beam with predetermined properties has the property of being focused to a single spot with a spot size smaller than 300 microns; and in which the focused x-ray spot corresponds to a predetermined position on the surface of the specimen.

6. The x-ray system of claim 1 , in which
said substrate comprises a material with a thermal conductivity greater than 0.1 W m −1 ° C. −1 .

7. The system of claim 1 , in which
the first selected material is selected from the group consisting of:
beryllium, diamond, graphite, silicon, boron nitride, silicon carbide, sapphire, and diamond-like carbon.

8. The system of claim 1 , in which
one or more materials selected for its x-ray generation properties is selected from the group consisting of:
aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, gallium, zinc, yttrium, zirconium, molybdenum, niobium, ruthenium, rhodium, palladium, silver, tin, iridium, tantalum, tungsten, indium, cesium, barium, gold, platinum, lead, and combinations and alloys thereof.

9. An x-ray measurement system, comprising:
an x-ray source, comprising:
a vacuum chamber;
a window transparent to x-rays attached to the wall of the vacuum chamber;
and, within the vacuum chamber:
at least one electron beam emitter; and
an anode target comprising:
a substrate comprising a first selected material, and
a planar first surface, from which thickness is measured in a direction perpendicular to the first planar surface, and
two orthogonal lateral dimensions are measured parallel to the first planar surface; and

a plurality of discrete structures embedded into the first planar surface of the substrate such that each of the plurality of discrete structures is in thermal contact with the substrate,
the plurality of discrete structures comprising a second material selected for its x-ray generation properties;

in which at least two of the plurality of discrete structures are arranged on a predetermined axis;
in which the axis is parallel to the first planar surface of the substrate;
in which the axis passes through the first window;
in which each of the discrete structures has a thickness of less than 20 microns, and
in which each of the plurality of discrete structures has a lateral dimension in the direction of the axis of less than 50 microns; and

a means of directing electrons emitted by the at least one electron beam emitter onto the at least two arranged discrete structures such that x-rays are generated from each of the at least two arranged discrete structures;
in which at least a portion of the generated x-rays propagating on the predetermined axis from each of the at least two arranged discrete structures is transmitted through the window;
an optical train having an optical axis to collect diverging x-rays generated by said at least two arranged discrete structures in the anode target,
and that produces an x-ray beam with predetermined beam properties;

said optical train additionally comprising a central beam stop positioned to block x-rays propagating parallel to said optical axis;
an adjustable mount to hold an object to be investigated,
positioned such that the x-ray beam will be incident on the object at an adjustable grazing angle smaller than the critical angle of the object; and

a detector to measure x-rays emerging from the object when x-rays are incident on the object.

10. The system of claim 9 , in which
said detector is positioned to detect x-rays that are diffracted by the object;
and additionally positioned such that a portion of the detector also measures the intensity of the x-rays reflected from the object.

11. The system of claim 9 , in which
both lateral dimensions parallel to said first planar surface of said at least two arranged discrete structures are less than 50 microns.

12. The system of claim 9 , in which
the plurality of discrete structures are arranged in a linear array along said predetermined axis; and
the optical axis of the optical train is also aligned along said predetermined axis.

13. The system of claim 9 , in which
the first selected material is selected from the group consisting of:
beryllium, diamond, graphite, silicon, boron nitride, silicon carbide, sapphire, and diamond-like carbon.

14. The system of claim 9 , in which
the second material is selected from the group consisting of:
aluminum, titanium, vanadium, chromium, manganese, iro

Assignees

• Sigray Inc

Inventors

• Yun Wenbing
• Lewis Sylvia Jia Yun
• Kirz Janos

Classifications

• G21K1/062

  Devices having a multilayer structure · CPC title

• G01N23/205 Primary

  using diffraction cameras · CPC title

• H01J2235/086

  Target geometry · CPC title

• H01J35/08

  Anodes; Anti cathodes · CPC title