Spectrometer for vacuum ultraviolet measurements in high-pressure environment

Patent metadata

Field	Value
Publication number	US-11035727-B2
Application number	US-201916296437-A
Country	US
Kind code	B2
Filing date	Mar 8, 2019
Priority date	Mar 13, 2018
Publication date	Jun 15, 2021
Grant date	Jun 15, 2021

Abstract

A spectrometer apparatus is disclosed. The apparatus may include light source and the light source may include a chamber for sustaining a plasma within the internal volume of the chamber. The apparatus may also include a spectrometer cavity and a windowless entrance slit. The windowless entrance slit may fluidically and optically couple the spectrometer cavity and the internal volume of the chamber of the light source. Further, the apparatus may include a diffractive element disposed within the spectrometer cavity and a window positioned at an opposite end of the spectrometer cavity from the windowless slit. The apparatus may also include a camera and a spectrometer.

First claim

What is claimed:

1. A spectrometer apparatus comprising:
a light source configured to generate light, wherein the light source includes a chamber for sustaining a plasma within an internal volume of the chamber, wherein the plasma emits the light in response to a pump beam;
a spectrometer cavity;
a windowless entrance slit, wherein the windowless entrance slit fluidically and optically couples the spectrometer cavity and the internal volume of the chamber of the light source;
a diffractive element disposed within the spectrometer cavity;
a window positioned at an opposite end of the spectrometer cavity from the windowless entrance slit, wherein a first portion of the window is coated with one or more scintillator materials and a second portion of the window is uncoated, wherein the diffractive element and the windowless entrance slit are positioned such that light transmitted through the windowless entrance slit illuminates the diffractive element and the diffractive element directs the light to the window;
a camera, wherein the camera is configured to image visible light emitted by the one or more scintillator materials of the window in response to the light from the diffractive element; and
a spectrometer configured to receive a portion of the light directed from the diffractive element and transmitted through the uncoated second portion of the window.

2. The spectrometer apparatus of claim 1 , wherein the light source
comprises:
a broadband light source or a narrowband light source.

3. The spectrometer apparatus of claim 2 wherein the light source
comprises:
one or more laser sustained plasma (LSP) sources or one or more gas discharge sources.

4. The spectrometer apparatus of claim 3 , wherein the light source is configured to emit at least vacuum ultraviolet (VUV) light.

5. The spectrometer apparatus of claim 1 , further comprising:
a ventilation path, wherein the ventilation path fluidically couples the spectrometer cavity and the internal volume of the chamber of the light source to equalize a pressure in the spectrometer cavity and a pressure in the chamber of the light source.

6. The spectrometer apparatus of claim 1 , wherein the window is positioned at a second focus plane of the diffractive element.

7. The spectrometer apparatus of claim 1 , wherein the diffractive element comprises a grating.

8. The spectrometer apparatus of claim 7 , wherein the grating is coated with platinum, bare aluminum, or protected aluminum.

9. The spectrometer apparatus of claim 1 , wherein the spectrometer is configured to receive a portion of zeroth-order light from the light directed from the diffractive element and transmitted through the uncoated second portion of the window through a separated window.

10. The spectrometer apparatus of claim 1 , wherein the window comprises:
a sapphire window.

11. The spectrometer apparatus of claim 1 , wherein an external surface of the window is coated with one or more anti-reflective layers.

12. The spectrometer apparatus of claim 1 , wherein the first portion of the window comprises a first window segment and the second portion of the window comprises second segment separated from the first window segment, wherein the first window segment is positioned at a second focus plane of the diffractive element, wherein the second window segment is positioned off focus of zeroth-order light from the diffractive element.

13. The spectrometer apparatus of claim 1 , wherein the one or more scintillator materials of the window comprise:
one or more fluorescent materials.

14. The spectrometer apparatus of claim 1 , wherein the spectrometer is configured to acquire one or more spectra from the light from the diffractive element above 150 nm.

15. The spectrometer apparatus of claim 1 , wherein the camera is configured to image visible light emitted by the one or more scintillator materials in response to light from the diffractive element below 150 nm.

16. The spectrometer apparatus of claim 15 , wherein the camera is configured to image visible light emitted by the one or more scintillator materials in response to light from the diffractive element below 120 nm.

17. The spectrometer apparatus of claim 16 , wherein the camera is configured to image visible light emitted by the one or more scintillator materials in response to light from the diffractive element below 100 nm.

18. The spectrometer apparatus of claim 1 , wherein the spectrometer comprises:
a broadband spectrometer or a narrowband spectrometer.

19. The spectrometer apparatus of claim 18 , wherein the spectrometer comprises:
an imaging broadband spectrometer.

20. A spectrometer apparatus comprising:
a spectrometer cavity;
a windowless entrance slit disposed at an entrance portion of the spectrometer cavity, wherein the windowless entrance slit is configured to fluidically and optically couple the spectrometer cavity to a chamber of a light source;
a diffractive element disposed within the spectrometer cavity;
a window positioned at an opposite end of the spectrometer cavity from the windowless entrance slit, wherein a first portion of the window is coated with one or more scintillator materials and a second portion of the window is uncoated, wherein the diffractive element and the windowless entrance slit are positioned such that light transmitted through the windowless entrance slit illuminates the diffractive element and the diffractive element directs the light to the window;
a camera, wherein the camera is configured to image visible light emitted by the one or more scintillator materials of the window in response to light from the diffractive element; and
a spectrometer configured to receive a portion of the light directed from the diffractive element and transmitted through an uncoated second portion of the window.

21. The spectrometer apparatus of claim 20 , wherein the light source comprises:
a broadband light source or a narrowband light source.

22. The spectrometer apparatus of claim 21 , wherein the light source comprises:
one or more laser sustained plasma (LSP) sources or one or more gas discharge sources.

23. The spectrometer apparatus of claim 22 , wherein the light source is configured to emit at least vacuum ultraviolet (VUV) light.

24. The spectrometer apparatus of claim 20 , wherein the spectrometer is configured to acquire one or more spectra from the light from the diffractive element above 150 nm.

25. The spectrometer apparatus of claim 20 , wherein the camera is configured to image visible light emitted by the one or more scintillator materials in response to light from the diffractive element below 150 nm.

26. The spectrometer apparatus of claim 25 , wherein the camera is configured to image visible light emitted by the one or more scintillator materials in response to light from the diffractive element below 120 nm.

27. The spectrometer apparatus of claim 26 , wherein the camera is configured to image visible light emitted by the one or more scintillator materials in response to light from the diffractive element below 100 nm.

28. A method comprising:
generating light;
transmitting the light through an entrance slit of a spectrometer cavity and onto a diffractive element disposed within the spectrometer cavity;
directing diffracted light from the diffractive element through a first coated portion of a window of the

Assignees

• Kla Tencor Corp
• Kla Corp

Inventors

• Bezel Ilya
• Shchemelinin Anatoly

Classifications

• G01J3/0248

  using a sighting port, e.g. camera or human eye · CPC title

• G01J3/024 Primary

  using means for illuminating a slit efficiently (e.g. entrance slit of a spectrometer or entrance face of fiber) · CPC title

• G01J1/58 Primary

  using luminescence generated by light · CPC title

• G01J3/443

  Emission spectrometry · CPC title

• G01J3/0208

  using focussing or collimating elements, e.g. lenses or mirrors; performing aberration correction · CPC title