Integrated optical measurement instruments

• US 5,943,122 A
• Filed: 07/10/1998
• Issued: 08/24/1999
• Est. Priority Date: 07/10/1998
• Status: Expired due to Term

• Current Assignee: Nanometrics Incorporated
• Original Assignee: Nanometrics Incorporated
• Inventors: Holmes, Duane C.
• Primary Examiner(s): Evans, F. L.
• Application Number:
  US09/113,610
• Time in Patent Office: 410 Days
• Field of Search: 356/72, 356/73, 356/51, 356/319, 356/326, 356/328, 250/339.07, 250/339.08
• US Class Current: 356/73
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0235 using means for replacing an element by another, for replacing a filter or a grating
• CPC Class Codes: G01J 3/0291 Housings; Spectrometer accessories; Spatial arrangement of elements, e.g. folded path arrangements
• CPC Class Codes: G01J 3/4535 Devices with moving mirror G01J3/4532 takes precedence
• CPC Class Codes: G02B 21/248 objective (or ocular) turrets

Abstract

A measuring instrument with a parfocal combination of an ultra-violet to near-infrared (UV-NIR) spectrophotometer and a Fourier Transform Infrared (FTIR) spectrometer is disclosed. The parfocal configuration of metrology tools obviates lateral movement of the sample between two separate measurement instruments. Consequently, the area occupied by the parfocal measuring instrument is reduced. Moreover, throughput is increased because there is no need to reposition the sample to properly align the measurement area for the separate measurements. The measuring instrument also includes an imaging apparatus, such as a camera or microscope ocular, to accurately position the measurement area of the sample. Beam directing elements, such as a mirror and objective lenses, are mounted on a common movable member. The common movable member, which may be, e.g., a linear or rotating turret, moves to properly align the desired beam directing element, thereby selecting the specific metrology mode. In addition, the measurement instrument includes a purging shroud along the FTIR spectrometer optical path to efficiently purge any atmospherical gases that may interfere with the FTIR measurement technique.

Claims

1. A measurement instrument for the characterization and measurement of surface, thin-film, and bulk properties of a sample, said measuring instrument comprising:

a spectrophotometer measuring a first area of said sample; and

a spectrometer measuring a second area of said sample;

wherein said first area of said sample and said second area of said sample overlap, said spectrophotometer measures said first area of said sample and said spectrometer measures said second area of said sample with said sample maintained in approximately the same position.

2. The measurement instrument of claim 1, wherein said spectrometer is a Fourier Transform Infrared spectrometer.

3. The measurement instrument of claim 1, wherein said spectrophotometer uses light with wavelengths in the range of 0.2 μ

m through 1.5 μ

m.

4. The measurement instrument of claim 1, wherein said spectrophotometer and said spectrometer are parcentric.

5. The measurement instrument of claim 1, wherein said spectrophotometer and said spectrometer are parfocal.

6. The measurement instrument of claim 1 further comprising:

a first beam directing element for directing the beam for said spectrometer and a second beam directing element for directing the beam for said spectrophotometer, said first beam directing element and said second beam directing element mounted on a common movable member;

wherein the use of said spectrometer and said spectrophotometer is selectable by moving said common movable member to select one of said first beam directing element and said second beam directing element.

7. The measurement instrument of claim 6, wherein said first beam directing element comprises:

a first mirror for directing the beam from a spectrometer light source toward said sample; and

a second mirror for directing the beam from said sample toward a spectrometer detector;

wherein said second beam directing element comprises;

a first lens for directing the beam from a spectrophotometer light source toward said sample; and

a second lens for directing the beam from said sample toward a spectrophotometer detector.

8. The measurement instrument of claim 7, wherein:

said first mirror and said second mirror are the same mirror, said beam from said spectrometer light source is a first incident beam and said beam from said sample toward said spectrometer detector is a first reflected beam; and

said first lens and said second lens are the same lens, said beam from said spectrophotometer light source is a second incident beam and said beam from said sample toward said spectrophotometer detector is a second reflected beam.

9. The measurement instrument of claim 7, further comprising:

a second common movable member upon which is mounted said first mirror and said first lens, said second common movable member is positioned on the opposite side of said sample from said spectrometer detector and said spectrophotometer detector;

wherein said beam from said spectrometer light source is a first incident beam and said beam from said sample toward said spectrometer detector is a first transmitted beam, and said beam from said spectrophotometer light source is a second incident beam and said beam from said sample toward said spectrophotometer detector is a second transmitted beam.

10. The measurement instrument of claim 6, further comprising a plurality of beam directing elements for directing the beam for said spectrophotometer, said plurality of beam directing elements mounted on said common movable member.

11. The measurement instrument of claim 1, further comprising:

an imaging apparatus for locating a desired feature on said sample, and

means for moving said sample to place said desired feature at a desired position within the field of view of said imaging apparatus;

wherein said imaging apparatus is parfocal with said spectrophotometer and said spectrometer.

12. The measurement instrument of claim 11, wherein:

said imaging apparatus is a camera; and

said means for moving said sample is a microprocessor coupled to said camera and a stage upon which said sample is mounted, said microprocessor controlling the position of said stage.

13. The measurement instrument of claim 11, wherein said imaging apparatus comprises a plurality of viewing instruments for simultaneously viewing said desired feature on said sample.

14. The measurement instrument of claim 1, further comprising:

a purging shroud coupled to said spectrometer, said purging shroud directing a purging gas along the spectrometer optical path.

15. An apparatus for measuring characteristics of a sample, said apparatus comprising:

a stage for mounting said sample, said stage movable to position said sample at a desired location;

a first light source producing light with wavelengths between the ultraviolet and near infrared range, said light being focused at a first measurement area on a surface of said sample;

a spectrophotometer receiving said light with wavelengths between ultraviolet and near infrared from said first measurement;

a second light source producing light with wavelengths in the infrared range, said light being focused at a second measurement area on a surface of said sample; and

a spectrometer receiving said light with wavelengths in the infrared range from said second measurement area;

wherein said first measurement area and said second measurement area are coincident while holding said stage essentially stationary.

16. The apparatus of claim 15, wherein said light with wavelengths between ultraviolet and near infrared from said first measurement received by said spectrophotometer is light reflected by said sample and wherein said light with wavelengths in the infrared range from said second measurement area received by said spectrometer is light reflected by said sample.

17. The apparatus of claim 15, wherein said light with wavelengths between ultraviolet and near infrared from said first measurement received by said spectrophotometer is light transmitted through said sample and wherein said light with wavelengths in the infrared range from said second measurement area received by said spectrometer is light transmitted through said sample.

18. The apparatus of claim 15, wherein said light with wavelengths between ultraviolet and near infrared from said first measurement received by said spectrophotometer is light transmitted through said sample and wherein said light with wavelengths in the infrared range from said second measurement area received by said spectrometer is light reflected by said sample.

19. The apparatus of claim 15, wherein said light with wavelengths between ultraviolet and near infrared from said first measurement received by said spectrophotometer is light reflected by said sample and wherein said light with wavelengths in the infrared range from said second measurement area received by said spectrometer is light transmitted through said sample.

20. The apparatus of claim 15 further comprising:

a first beam directing element mounted on a common movable member, said first beam directing element for directing said light with wavelengths between ultraviolet and near infrared from said first measurement area received by said spectrophotometer;

a second beam directing element mounted on said common movable member, said second beam directing element for directing said light with wavelengths in the infrared range from said second measurement area received by said spectrometer;

wherein said common movable member is moved to select one of said first beam directing element and said second beam directing element.

21. The apparatus of claim 20, wherein said first beam directing element is an objective lens, said second beam directing element is a mirror, and said common movable member is a linear turret.

22. A method of measuring the surface, thin-film, and bulk properties of a sample, said method comprising:

illuminating a first area of said sample with light having a first wavelength;

detecting the light having a first wavelength from said sample with a spectrophotometer;

illuminating a second area of said sample with light having a second wavelength; and

detecting the light having a second wavelength from said sample with a spectrometer;

wherein said first area of said sample and said second area of said sample overlap and wherein said illuminating a first area and said illuminating a second area are performed with said sample maintained in approximately the same position.

23. The method of claim 22, wherein said first wavelength is a portion of wavelengths ranging from 0.2 μ

m through 1.5 μ

m, and wherein said second wavelength is between 2 mm and 1 mm.

24. The method of claim 23, wherein said detecting the light having a first wavelength from said sample comprises detecting at least one of light reflected from said sample and light transmitted through said sample.

25. The method of claim 24, wherein said detecting the light having a second wavelength from said sample comprises detecting at least one of light reflected from said sample and light transmitted through said sample.

26. The method of claim 22, further comprising moving a common movable member upon which is mounted a first beam directing element and a second beam directing element, wherein moving said common movable member places at least one of said spectrophotometer and spectrometer in alignment with said respective first area and said second area.