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Lamella-shaped Targets for X-ray Generation
| Content Provider | The Lens |
|---|---|
| Abstract | A method and system are disclosed for producing an x-ray image of a sample using a lamella-shaped target to improve the usual tradeoff between imaging resolution and image acquisition time. A beam of electrons impacts the lamella-shaped target normal to the narrower dimension of the lamella which then determines the virtual source size along that axis. For low-energy x-ray generation, the small electron penetration depth parallel to the wider dimension of the lamella determines the virtual source size along that axis. Conductive cooling of the target is improved over post targets with the same imaging resolution. The lamella-shaped target is long enough to ensure that the electron beam does not impact the support structure which would degrade the imaging resolution. Target materials may be selected from the same metals used for bulk or post targets, including tungsten, molybdenum, titanium, scandium, vanadium, silver, or a refractory metal. |
| Related Links | https://www.lens.org/lens/patent/011-449-898-967-698/frontpage |
| Language | English |
| Publisher Date | 2019-01-16 |
| Access Restriction | Open |
| Alternative Title | Lamellenförmige Targets Für Die Röntgengenerierung Cibles En Forme De Lamelle Pour La Génération De Rayons X |
| Content Type | Text |
| Resource Type | Patent |
| Date Applied | 2018-07-10 |
| Agent | Janssen, Francis-paul |
| Applicant | Fei Co |
| Application No. | 18182591 |
| Claim | A method for producing an x-ray image of a sample, the method comprising: directing a beam of electrons having landing energies of less than 2,000 eV along a first axis onto a first surface of a lamella-shaped target, the impact of the electrons in the beam onto the lamella-shaped target generating x-rays from within an interaction volume within the lamella-shaped target, wherein a portion of the x-rays are emitted towards an x-ray detector; positioning a sample along a second axis between the lamella-shaped target and the x-ray detector; and acquiring an x-ray image by collecting the x-rays which are not absorbed by the sample using the x-ray detector, in which: the lamella-shaped target has a height in a direction along the first axis, a length in a direction along the second axis, and a width along a third axis that is different from the first and second axes; the height and the length are at least twice the width; and the electron beam interaction volume extends along the first axis from the first surface a distance of less than the height of the lamella-shaped target, thereby providing a virtual x-ray source in which the virtual source size along the first axis is determined not by the height of the lamella-shaped target but by the extent of the interaction volume along the first axis. The method of claim 1 in which directing a beam of electrons comprises directing a beam of electrons having at the target surface a diameter greater than the width of the lamella-shaped target. The method of any of claims 1-2 in which the interaction volume extends from the first surface to a distance of less than one half the height of the lamella-shaped target, in particular in which the interaction volume extends from the first surface to a distance of less than one quarter the height of the lamella-shaped target. The method of any of claims 1-3 in which the height and the length are both at least twice the width, in particular in which the height and the length are both greater than 500 nm and the width is less than 200 nm. The method of any of claims 1-4 further comprising: a) rotating the sample; b) directing the electron beam onto a first surface of a lamella-shaped target; c) acquiring a subsequent x-ray image; d) repeating steps a) b) and c) to acquire a multiplicity of x-ray images; and e) processing the multiplicity of x-ray images to form a 3D tomographic reconstruction of the sample. The method of any of claims 1-5 wherein directing a beam of electrons having landing energies of less than 2000 eV along a first axis onto a first surface of a lamella-shaped target comprises directing an electron beam in which the electrons have landing energies in the range of 1500 to 2000 eV, or wherein the beam of electrons has a landing energy of less than 1500 eV. A method for producing an x-ray image of a sample, the method comprising: directing an electron beam along a first axis onto a first surface of a lamella-shaped target, the impact of the electrons in the beam onto the lamella-shaped target generating x-rays, wherein a portion of the x-rays are emitted towards an x-ray detector; positioning a sample along a second axis between the lamella-shaped target and the x-ray detector; and acquiring an x-ray image by collecting the x-rays which are not absorbed by the sample using the x-ray detector, in which the lamella-shaped target has a height in a direction along the first axis, a length in a direction along the second axis, and a width along a third axis that is different from the first and second axes, the height and the length being at least twice the width. The method claim 7 in which the height and the length are at least three times the width. The method of any of claims 7-8 further comprising: a) rotating the sample; b) directing the electron beam onto a first surface of a lamella-shaped target; c) acquiring a subsequent x-ray image; d) repeating steps a) b) and c) to acquire a multiplicity of x-ray images; and processing the multiplicity of x-ray images to form a 3D tomographic reconstruction of the sample. The method of any of claims 7-9 in which directing the electron beam onto a first surface of a lamella-shaped target comprises directing an electron beam in which the electrons have landing energies in the range of 1500 to 2000 eV. The method of claim 10 in which directing the electron beam onto a first surface of a lamella-shaped target comprises directing an electron beam in which the electrons have a penetration depth of equal to the less than twice the width of the lamella-shaped target. The method of any of claims 1-11 in which the length and the height are equal to or greater than 200 nm and the width is equal to or less than 200 nm, in particular in which the length and the height are equal to or greater than 1 µm and the width is equal to or less than 200 nm, and/or in which the ratio of the depth to the width is at least 5:1. A system for acquiring x-ray images from a sample, comprising: an electron column for producing an electron beam along a first axis; a lamella-shaped target positioned at a target position such that the lamella-shaped target will be impacted by the electron beam; a sample stage, such as a rotatable sample stage, for positioning the sample at a sample position at which the sample will be impacted by x-rays emitted from the target upon impact of the electron beam onto the target; and an x-ray detector for collecting x-rays emitted from the target due to impact by the electron beam and passing through the sample, a line from the lamella-shaped target through the sample position to the x-ray detector defining a second axis; in which the lamella-shaped target has a height in a direction along the first axis, a length in a direction along the second axis, and a width in a direction normal to the first and second axes, the height and the length being at least twice the width. The system for acquiring x-ray images from a sample of claim 13, further comprising: a controller for controlling the acquiring x-ray images from a sample; and a computer memory, configured to store machine readable instructions to be executed by the controller, in particular in which the computer memory stores instructions to: repeatedly acquire an x-ray image of the sample and rotate the sample; and combine the repeatedly acquired images to produce a three-dimensional representation of the sample. The system for acquiring x-ray images from a sample of any of claims 13-14, wherein the lamella-shaped target is fabricated from a group of x-ray producing materials consisting of: tungsten, molybdenum, titanium, scandium, vanadium, silver, or a refractory meta |
| CPC Classification | Investigating Or Analysing Materials By Determining Their Chemical Or Physical Properties Techniques For Handling Particles Or Ionising Radiation Not Otherwise Provided For;Irradiation Devices;Gamma Ray Or X-Ray Microscopes Electric Discharge Tubes Or Discharge Lamps |
| Extended Family | 022-933-599-703-08X 147-010-617-743-278 077-043-391-203-642 078-027-730-207-733 011-449-898-967-698 115-467-123-573-204 007-303-157-132-275 |
| Patent ID | 3428928 |
| Inventor/Author | Filevich Jorge |
| IPC | G21K7/00 |
| Status | Pending |
| Simple Family | 022-933-599-703-08X 147-010-617-743-278 077-043-391-203-642 078-027-730-207-733 011-449-898-967-698 115-467-123-573-204 007-303-157-132-275 |
| CPC (with Group) | G01N23/046 G01N2223/204 G01N2223/419 G21K7/00 H01J35/08 H01J2235/081 H01J2235/086 G01N2223/401 |
| Issuing Authority | United States Patent and Trademark Office (USPTO) |
| Kind | Patent Application Publication |
