High brightness X-ray metrology

• US 7,929,667 B1
• Filed: 09/29/2009
• Issued: 04/19/2011
• Est. Priority Date: 10/02/2008
• Status: Active Grant

• Current Assignee: KLA-Tencor Corporation
• Original Assignee: KLA-Tencor Corporation
• Inventors: Fielden, John, Zhuang, Guorong V.
• Primary Examiner(s): Kiknadze; Irakli
• Application Number:
  US12/569,833
• Time in Patent Office: 567 Days
• Field of Search: 378/42, 378/44, 378/45, 378/70, 378/71, 378/119, 378/143
• US Class Current: 378/119
• CPC Class Codes: H05G 2/003 being produced from a liquid or gas
• CPC Class Codes: H05G 2/005 containing a metal as principal radiation generating component

Abstract

An x-ray metrology tool having only one x-ray source. The x-ray source includes a liquid metal source for heating and melting at least one metal and producing a liquid metal jet, a liquid metal collector for acquiring the liquid metal jet, a liquid metal circulation system for returning liquid metal from the liquid metal collector to the liquid metal source, and an electron beam source for directing an electron beam at the liquid metal jet anode, thereby producing an incident x-ray beam that is directable towards a sample. A detector receives emissions from the sample in response to the incident x-ray beam, and produces signals indicative of properties of the sample. A controller controls the x-ray source, acquires the signals from the detector, and determines the properties of the sample based at least in part on the signals.

Claims

1. An x-ray metrology tool comprising:

only one x-ray source, comprising,

a liquid metal source for heating and melting at least one metal and producing a liquid metal jet,

a liquid metal collector for acquiring the liquid metal jet,

a liquid metal circulation system for returning liquid metal from the liquid metal collector to the liquid metal source, and

an electron beam source for directing an electron beam at the liquid metal jet, thereby producing an incident x-ray beam that is directable towards a sample,

a detector for receiving emissions from the sample in response to the incident x-ray beam and producing signals indicative of properties of the sample, and

a controller for controlling the x-ray source, acquiring the signals from the detector, and determining the properties of the sample based at least in part on the signals.

2. The x-ray metrology tool of claim 1, wherein the tool is configured to perform one of x-ray reflectometry, small angle x-ray scattering, critical dimension small angle x-ray scattering, grazing incident x-ray reflectometry, x-ray photoelectron spectroscopy, x-ray diffraction, total reflection x-ray fluorescence, and x-ray fluorescence.

3. The x-ray metrology tool of claim 1, wherein the x-ray source is operated continuously and not pulsed during signal acquisition.

4. The x-ray metrology tool of claim 1, wherein the metal and the liquid metal jet comprises more than one element.

5. The x-ray metrology tool of claim 1, wherein the metal and the liquid metal jet comprise at least one of gallium, thallium, indium, bismuth, and tin.

6. The x-ray metrology tool of claim 1, wherein the x-ray beam comprises photons at only one peak energy and wavelength.

7. The x-ray metrology tool of claim 1, wherein the x-ray beam comprises photons at only two peak energies and wavelengths.

8. The x-ray metrology tool of claim 1, wherein the x-ray beam comprises photons at more than two peak energies and wavelengths.

9. The x-ray metrology tool of claim 1, wherein:

the tool is configured to perform x-ray reflectometry, and

the detector comprises two separate CCD detectors in two separate sections of angular space that each produce signals simultaneously and independently, which signals are independently acquired and analyzed by the controller.

10. The x-ray metrology tool of claim 1, wherein:

the tool is configured to perform x-ray reflectometry, and

the detector comprises a single CCD detector having two sections that each produce signals simultaneously and independently, which signals are independently acquired and analyzed by the controller.

11. The x-ray metrology tool of claim 1, further comprising:

the metal and the liquid metal jet comprise more than one element,

the x-ray beam comprises non-Bremsstrahlung radiation concurrently having first photons at a first peak energy and a first peak wavelength and second photons at a second peak energy that is different from the first peak energy and a second peak wavelength that is different from the first peak energy,

a grating for receiving the x-ray beam and directing the first photons along a first path and the second photons along a second path that is different from the first path,

where the first path impinges a spot on the sample at a first grazing angle,

where the second path impinges the spot on the sample at a second grazing angle that is different from the first grazing angle,

the detector comprises a first detector and a separate second detector, the first detector for receiving first emissions from the sample in response to the first photons and producing first signals indicative of first properties of the sample, the second detector for receiving second emissions from the sample in response to the second photons and producing second signals indicative of second properties of the sample,

the controller for acquiring the first signals and the second signals, and determining the first properties and the second properties of the sample based at least in part on the first signals and the second signals.

12. The x-ray metrology tool of claim 11, wherein the tool is configured to perform both x-ray reflectometry and x-ray fluorescence.

13. The x-ray metrology tool of claim 11, wherein the first properties comprise at least one of layer thickness and structure size and the second properties comprise at least one of elemental identification and composition.

14. The x-ray metrology tool of claim 11, wherein the x-ray source is operated continuously and not pulsed during signal acquisition.

15. A combined x-ray reflectometry and x-ray fluorescence metrology tool comprising:

only one x-ray source, comprising,

a liquid metal source for heating and melting two metals and producing a liquid metal jet,

a liquid metal collector for acquiring the liquid metal jet,

a liquid metal circulation system for returning liquid metal from the liquid metal collector to the liquid metal source, and

an electron beam source for directing an electron beam at the liquid metal jet, thereby producing an incident x-ray beam that is directable towards a sample, the x-ray beam comprising non-Bremsstrahlung radiation concurrently having first photons at a first peak energy and a first peak wavelength and second photons at a second peak energy that is different from the first peak energy and a second peak wavelength that is different from the first peak energy,

a grating for receiving the x-ray beam and directing the first photons along a first path and the second photons along a second path that is different from the first path,

where the first path impinges a spot on the sample at a first grazing angle,

where the second path impinges the spot on the sample at a second grazing angle that is different from the first grazing angle,

a first detector for receiving first emissions from the sample in response to the first photons and producing first signals indicative of first properties of the sample,

a second detector that is different from the first detector for receiving second emissions from the sample in response to the second photons and producing second signals indicative of second properties of the sample, and

a controller for controlling the x-ray source, acquiring the first signals from the first detector, acquiring the second signals from the second detector, and determining the properties of the sample based at least in part on the first signals and the second signals.

16. The x-ray metrology tool of claim 15, wherein the first properties comprise at least one of layer thickness and structure size and the second properties comprise at least one of elemental identification and composition.

17. The x-ray metrology tool of claim 15, wherein the x-ray source is operated continuously and not pulsed during signal acquisition.

18. The x-ray metrology tool of claim 15, wherein the metal and the liquid metal jet comprise gallium and indium.