X-ray detection optics for small-angle X-ray scatterometry

• US 20190323974A1
• Filed: 04/17/2019
• Published: 10/24/2019
• Est. Priority Date: 04/23/2018
• Status: Active Grant

• Current Assignee: Bruker Technologies Ltd. (Bruker Corporation)
• Original Assignee: Bruker JV Israel, Ltd. (Bruker Corporation)
• Inventors: Wormington, Matthew, Peled, Asher, Krokhmal, Alexander
• Granted Patent: US 10,976,270 B2
• Time in Patent Office: Days
• CPC Class Codes: G01N 2223/303 calibrating, standardising
• CPC Class Codes: G01N 2223/32 adjustments of elements during operation
• CPC Class Codes: G01N 2223/33 scanning, i.e. relative motion for measurement of successive object-parts
• CPC Class Codes: G01N 2223/3301 beam is modified for scan, e.g. moving collimator
• CPC Class Codes: G01N 2223/6116 semiconductor wafer
• CPC Class Codes: G01N 23/20025 Sample holders or supports therefor
• CPC Class Codes: G01N 23/20091 Measuring the energy-dispersion spectrum [EDS] of diffracted radiation
• CPC Class Codes: G01N 23/201 by measuring small-angle scattering
• CPC Class Codes: G01N 23/2055 Analysing diffraction patterns
• CPC Class Codes: G01N 23/207 Diffractometry using detectors, e.g. using a probe in a central position and one or more displaceable detectors in circumferential positions
• CPC Class Codes: G01N 23/223 by irradiating the sample with X-rays or gamma-rays and by measuring X-ray fluorescence

Abstract

An X-ray apparatus includes a mount, an X-ray source, a detector, an actuator, and a controller. The mount is configured to hold a sample. The X-ray source is configured to direct a beam of X-rays toward a first side of the sample. The detector is positioned on a second side of the sample, opposite the first side, so as to receive at least a portion of the X-rays that have been transmitted through the sample and to output signals indicative of an intensity of the received X-rays. The actuator is configured to scan the detector over a range of positions on the second side of the sample so as to measure the transmitted X-rays as a function of a scattering angle. The controller is coupled to receive the signals output by the detector and to control the actuator, responsively to the signals, so as to increase an acquisition time of the detector at first positions where the intensity of the received X-rays is weak relative to the acquisition time at second positions where the intensity of the received X-rays is strong.

Claims

1. X-ray apparatus, comprising:

a mount, which is configured to hold a sample;

an X-ray source, which is configured to direct a beam of X-rays toward a first side of the sample;

a detector, which is positioned on a second side of the sample, opposite the first side, so as to receive at least a portion of the X-rays that have been transmitted through the sample and to output signals indicative of an intensity of the received X-rays;

an actuator, which is configured to scan the detector over a range of positions on the second side of the sample so as to measure the transmitted X-rays as a function of a scattering angle; and

a controller, which is coupled to receive the signals output by the detector and to control the actuator, responsively to the signals, so as to increase an acquisition time of the detector at first positions where the intensity of the received X-rays is weak relative to the acquisition time at second positions where the intensity of the received X-rays is strong.

2. The apparatus according to claim 1, wherein the detector comprises an array of sensor elements having a predefined pitch, and wherein the actuator is configured to step the detector across the range of positions with a resolution that is finer than the predefined pitch.

3. The apparatus according to claim 2, wherein the array comprises a two-dimensional matrix of the sensor elements, and the actuator is configured to step the detector with the resolution that is finer than the pitch along both height and width axes of the matrix.

4. The apparatus according to claim 1, wherein the sample comprises one or more high aspect ratio (HAR) features having an aspect ratio larger than ten, and wherein the actuator is configured to scan the detector over the range of positions so as to measure the transmitted X-rays scattered from the HAR features.

5. The apparatus according to claim 1, wherein the controller is configured to control the acquisition time so that the detector receives a predefined intensity range at the first and second positions.

6. A method, comprising:

holding a sample on a mount;

directing a beam of X-rays toward a first side of the sample;

receiving, from a detector positioned on a second side of the sample, opposite the first side, at least a portion of the X-rays that have been transmitted through the sample, and outputting signals indicative of an intensity of the received X-rays;

scanning, by an actuator, the detector over a range of positions on the second side of the sample so as to measure the transmitted X-rays as a function of a scattering angle; and

receiving the signals output by the detector and controlling the actuator, responsively to the signals, so as to increase an acquisition time of the detector at first positions where the intensity of the received X-rays is weak relative to the acquisition time at second positions where the intensity of the received X-rays is strong.

7. The method according to claim 6, wherein the detector comprises an array of sensor elements having a predefined pitch, and wherein scanning the detector comprises stepping the detector across the range of positions with a resolution that is finer than the predefined pitch.

8. The method according to claim 7, wherein the array comprises a two-dimensional matrix of the sensor elements, and scanning the detector comprises stepping the detector with the resolution that is finer than the pitch along both height and width axes of the matrix.

9. The method according to claim 6, wherein the sample comprises one or more high aspect ratio (HAR) features having an aspect ratio larger than ten, and measuring the transmitted X-rays scattered from the HAR features by scanning the detector over the range of positions.

10. The method according to claim 6, wherein controlling the actuator comprises controlling the acquisition time so that the detector receives a predefined intensity range at the first and second positions.

11. X-ray apparatus, comprising:

a first mount, which is configured to hold a sample;

an X-ray source, which is configured to direct a beam of X-rays toward the sample;

a detector, which is positioned to receive the X-rays that have been transmitted through the sample, wherein at least part of the transmitted beams are scattered from the sample over a range of angles; and

a beam blocker, which comprises a second mount made of a material that is transparent to the X-rays and one or more pieces of an X-ray opaque material held within the second mount, and which is positionable so that the X-ray opaque material blocks the X-rays in a part of the range of angles, while the X-rays at the angles surrounding the blocked part of the range pass through the mount to the detector.

12. The apparatus according to claim 11, wherein at least one of the pieces of the X-ray opaque material is ellipsoidal.

13. The apparatus according to claim 11, wherein the mount comprises a polymer.

14. The apparatus according to claim 11, wherein the mount comprises diamond.

15. The apparatus according to claim 11, wherein at least part of the blocked X-rays comprise X-rays transmitted through the sample without being scattered.

16. The apparatus according to claim 11, and comprising a processor, which is configured to measure an intensity of the X-rays received by the detector, and to position the beam blocker relative to the transmitted beam responsively to the measured intensity.

17. The apparatus according to claim 11, wherein at least one of the pieces of the X-ray opaque material is held within a recess of the mount.

18. The apparatus according to claim 11, wherein the mount comprises a sheet made from (i) biaxially-oriented polyethylene terephthalate (BoPET) polyester, or (ii) poly (4,4′

-oxydiphenylene-pyromellitimide) polyimide.

19. The apparatus according to claim 11, wherein at least one of the pieces of the X-ray opaque material comprises gold, tantalum, or tungsten.

20. The apparatus according to claim 11, wherein the pieces of the X-ray opaque material comprise at least a first piece and a second piece, having a different size and laid out in an array at a predefined distance from one another.