Semiconductor metrology based on hyperspectral imaging

Patent metadata

Field	Value
Publication number	US-10801953-B2
Application number	US-201916245695-A
Country	US
Kind code	B2
Filing date	Jan 11, 2019
Priority date	Jan 11, 2019
Publication date	Oct 13, 2020
Grant date	Oct 13, 2020

Abstract

Methods and systems for performing semiconductor measurements based on hyperspectral imaging are presented herein. A hyperspectral imaging system images a wafer over a large field of view with high pixel density over a broad range of wavelengths. Image signals collected from a measurement area are detected at a number of pixels. The detected image signals from each pixel are spectrally analyzed separately. In some embodiments, the illumination and collection optics of a hyperspectral imaging system include fiber optical elements to direct illumination light from the illumination source to the measurement area on the surface of the specimen under measurement and fiber optical elements to image the measurement area. In another aspect, a fiber optics collector includes an image pixel mapper that couples a two dimensional array of collection fiber optical elements into a one dimensional array of pixels at the spectrometer and the hyperspectral detector.

First claim

What is claimed is:

1. A metrology system comprising:
one or more hyperspectral imaging based metrology tools each comprising:
an illumination source configured to provide an amount of broadband illumination light;
an optical subsystem configured to direct the amount of illumination light from the illumination source to a measurement area on a surface of the semiconductor wafer under measurement and image the measurement area on the surface of the semiconductor wafer to a field plane conjugate to the surface of the semiconductor wafer over a field of view having a dimension of at least 250 micrometers at the semiconductor wafer; and
a spectrometer configured to disperse the imaged measurement area at or near the field plane conjugate to the surface of the semiconductor wafer; and
a hyperspectral detector configured to detect a spectral response of the semiconductor wafer to the amount of broadband illumination light at each of a plurality of pixels spanning the imaged measurement area.

2. The metrology system of claim 1 , wherein each hyperspectral imaging based metrology tool is configured as a reflectometer or an ellipsometer.

3. The metrology system of claim 1 , wherein each of the plurality of pixels is characterized by an area having at least one dimension smaller than 50 micrometers.

4. The metrology system of claim 1 , wherein the amount of broadband illumination light includes wavelengths ranging from 190 nanometers or less to 860 nanometers or more.

5. The metrology system of claim 1 , wherein the optical subsystem is configured to direct the amount of illumination light from the illumination source to the measurement area on the surface of the semiconductor wafer at an oblique angle of incidence.

6. The metrology system of claim 5 , wherein the measurement area is characterized by a first dimension less than 50 micrometers and a second dimension orthogonal to the first dimension greater than 1 millimeter.

7. The metrology system of claim 1 , the optical subsystem comprising:
a plurality of illumination fiber optical elements configured to direct the amount of illumination light from the illumination source to a measurement area on a surface of the semiconductor wafer; and
a plurality of collection fiber optical elements configured to image the measurement area on the surface of the semiconductor wafer to the field plane conjugate to the surface of the semiconductor wafer.

8. The metrology system of claim 7 , wherein the illumination fiber optical elements are the same fiber optical elements as the collection fiber optical elements.

9. The metrology system of claim 7 , wherein the plurality of collection fiber optical elements image the measurement area on the surface of the semiconductor wafer to the field plane conjugate to the surface of the semiconductor wafer along a one dimensional array of pixels.

10. The metrology system of claim 9 , wherein the spectrometer projects the imaged measurement area onto the hyperspectral detector along a first dimension of the hyperspectral detector and spatially disperses the imaged measurement area according to wavelength along a second dimension of the hyperspectral detector.

11. The metrology system of claim 1 , wherein the hyperspectral detector includes a photosensitive area subdivided into a plurality of spatially distinct zones, wherein each zone of the plurality of spatially distinct zones is sensitive to a different polarization state or range of wavelengths.

12. The metrology system of claim 1 , further comprising:
one or more non-imaging metrology tools configured to perform measurements of the semiconductor wafer.

13. The metrology system of claim 12 , wherein the measurements performed by the one or more non-imaging metrology tools and the spectral response at each of the plurality of pixels spanning the imaged measurement area are employed to estimate values of parameters of interest associated with intra-field, in-die targets or device areas.

14. A hyperspectral imaging based metrology tool, comprising:
an illumination source configured to provide an amount of broadband illumination light;
an optical subsystem configured to direct the amount of illumination light from the illumination source to a measurement area on a surface of the semiconductor wafer under measurement and image the measurement area on the surface of the semiconductor wafer to a field plane conjugate to the surface of the semiconductor wafer over a field of view having a dimension of at least 250 micrometers at the semiconductor wafer; and
a spectrometer configured to disperse the imaged measurement area at or near the field plane conjugate to the surface of the semiconductor wafer; and
a hyperspectral detector configured to detect a spectral response of the semiconductor wafer to the amount of broadband illumination light at each of a plurality of pixels spanning the imaged measurement area.

15. The hyperspectral imaging based metrology tool of claim 14 , wherein the optical subsystem is configured to direct the amount of illumination light from the illumination source to the measurement area on the surface of the semiconductor wafer at an oblique angle of incidence.

16. The hyperspectral imaging based metrology tool of claim 14 , the optical subsystem comprising:
a plurality of illumination fiber optical elements configured to direct the amount of illumination light from the illumination source to a measurement area on a surface of the semiconductor wafer; and
a plurality of collection fiber optical elements configured to image the measurement area on the surface of the semiconductor wafer to the field plane conjugate to the surface of the semiconductor wafer.

17. The hyperspectral imaging based metrology tool of claim 16 , wherein the plurality of collection fiber optical elements image the measurement area on the surface of the semiconductor wafer to the field plane conjugate to the surface of the semiconductor wafer along a one dimensional array of pixels.

18. The hyperspectral imaging based metrology tool claim 14 , wherein the spectrometer projects the imaged measurement area onto the hyperspectral detector along a first dimension of the hyperspectral detector and spatially disperses the imaged measurement area according to wavelength along a second dimension of the hyperspectral detector.

19. The hyperspectral imaging based metrology tool of claim 14 , wherein the hyperspectral detector includes a photosensitive area subdivided into a plurality of spatially distinct zones, wherein each zone of the plurality of spatially distinct zones is sensitive to a different polarization state or range of wavelengths.

20. A method comprising:
providing an amount of broadband illumination light;
directing the amount of illumination light from an illumination source to a measurement area on a surface of a semiconductor wafer under measurement;
imaging an amount of light collected from the measurement area on the surface of the semiconductor wafer to a field plane conjugate to the surface of the semiconductor wafer over a field of view having a dimension of at least 250 micrometers at the semiconductor wafer;
dispersing the amount of collected light at or near the field plane conjugate to the surface of the semiconductor wafer; and
detecting a spectral response of the semiconductor wafer to the amount of broadband illumination light at each of a plurality of pixels spanning the imaged measurement area.

21. The metrology system of claim 1 , further comprising

Assignees

• Kla Tencor Corp

Inventors

• Wang David Y
• Buettner Alexander
• Pandev Stilian Ivanov
• Saerchen Emanuel
• Shchegrov Andrei V
• Blasenheim Barry

Classifications

• H10P74/203

  Structural properties, e.g. testing or measuring thicknesses, line widths, warpage, bond strengths or physical defects · CPC title

• H10P74/23

  characterised by multiple measurements, corrections, marking or sorting processes · CPC title

• G01N2201/08

  Optical fibres; light guides · CPC title

• G01N2021/3568

  applied to semiconductors, e.g. Silicon · CPC title

• G01N2021/213

  Spectrometric ellipsometry · CPC title