Bandgap measurements of patterned film stacks using spectroscopic metrology

Patent metadata

Field	Value
Publication number	US-11378451-B2
Application number	US-201715672120-A
Country	US
Kind code	B2
Filing date	Aug 8, 2017
Priority date	Aug 7, 2017
Publication date	Jul 5, 2022
Grant date	Jul 5, 2022

Abstract

A spectroscopic metrology system includes a spectroscopic metrology tool and a controller. The controller generates a model of a multilayer grating including two or more layers, the model including geometric parameters indicative of a geometry of a test layer of the multilayer grating and dispersion parameters indicative of a dispersion of the test layer. The controller further receives a spectroscopic signal of a fabricated multilayer grating corresponding to the modeled multilayer grating from the spectroscopic metrology tool. The controller further determines values of the one or more parameters of the modeled multilayer grating providing a simulated spectroscopic signal corresponding to the measured spectroscopic signal within a selected tolerance. The controller further predicts a bandgap of the test layer of the fabricated multilayer grating based on the determined values of the one or more parameters of the test layer of the fabricated structure.

First claim

What is claimed:

1. A spectroscopic metrology system, comprising:
a spectroscopic metrology tool; and
a controller communicatively coupled to the spectroscopic metrology tool, the controller including one or more processors configured to execute program instructions configured to cause the one or more processors to:
generate a model of a metrology target including a multilayer grating, wherein the multilayer grating is formed from a patterned substrate layer and two or more additional layers on the patterned substrate layer to form a multilayer pattern, the two or more additional layers forming a multilayer stack shaped to conform to at least a portion of the patterned substrate layer, the two or more additional layers including a test layer to be modeled, wherein at least one of a size or spacing of elements of the multilayer pattern are representative of device features to be fabricated on a common sample with the metrology target, wherein the model is parameterized with two or more parameters associated with the multilayer grating, wherein the two or more parameters include one or more geometric parameters indicative of at least a size, shape, or periodicity of the test layer within the elements of the multilayer pattern, wherein the two or more parameters include one or more dispersion parameters indicative of at least a bandgap of the test layer including dimension-dependent physical effects associated with the one or more geometric parameters;
receive a measured spectroscopic signal grating from the spectroscopic metrology tool indicative of radiation emanating from a fabricated multilayer grating in response to incident illumination, wherein the fabricated multilayer grating is formed according to the model of the metrology target;
determine values of the two or more parameters of the model providing a simulated spectroscopic signal corresponding to the measured spectroscopic signal within a selected tolerance; and
calculate a metrology metric indicative of the bandgap of the test layer of the fabricated multilayer grating based on the determined values of the two or more parameters.

2. The spectroscopic metrology system of claim 1 , wherein the metrology metric comprises:
an integral of a dispersion curve of the test layer over a transition spectral region, wherein the integral is proportional to the bandgap of the test layer, wherein the dispersion curve is defined by the determined values of the one or more dispersion parameters, wherein the transition region comprises:
a range over which the dispersion curve varies exponentially within a selected transition tolerance.

3. The spectroscopic metrology system of claim 2 , wherein the dispersion curve of the test layer defined by the determined values of the one or more dispersion parameters is reconstructed to include an Urbach tail that varies exponentially within the transition spectral region.

4. The spectroscopic metrology system of claim 1 , wherein the one or more dispersion parameters include at least one of an extinction coefficient of the test layer, an imaginary part of a dielectric function of the test layer, or the bandgap of the test layer.

5. The spectroscopic metrology system of claim 4 , wherein at least one of the one or more dispersion parameters correspond to modeling parameters of a dispersion model.

6. The spectroscopic metrology system of claim 5 , wherein the dispersion model comprises:
at least one of a Bruggeman Effective Model Approximation model, a Cody Lorenz Continuous model, a Tauc-Lorentz model, a harmonic oscillator model, or a point-to-point model.

7. The spectroscopic metrology system of claim 5 , wherein the at least one of the one or more dispersion parameters of the dispersion model is sensitive to defect states in the test layer.

8. The spectroscopic metrology system of claim 1 , wherein the one or more geometric parameters include a thickness of at least one layer of the multilayer grating.

9. The spectroscopic metrology system of claim 1 , wherein the multilayer pattern comprises:
a grating structure including periodically-distributed elements formed from the test layer and the at least one additional layer of the multilayer grating.

10. The spectroscopic metrology system of claim 9 , wherein the one or more geometric parameters further include at least one of a height of the periodically-distributed elements, a width of the periodically-distributed elements at a selected measurement height, or a sidewall angle of the periodically-distributed elements.

11. The spectroscopic metrology system of claim 9 , wherein the periodically-distributed elements are distributed in one or more directions along a surface of the multilayer grating.

12. The spectroscopic metrology system of claim 11 , wherein the multilayer grating comprises:
a fin grating.

13. The spectroscopic metrology system of claim 1 , wherein the metrology metric is indicative of a leakage current of a transistor device fabricated with a common fabrication process.

14. The spectroscopic metrology system of claim 13 , further comprising:
predicting a performance of the transistor device based on the metrology metric.

15. The spectroscopic metrology system of claim 14 , further comprising:
predicting a performance of the transistor device based on the metrology metric and further based on at least one of the two or more determined parameters.

16. The spectroscopic metrology system of claim 1 , further comprising:
controlling one or more process tools for fabricating the multilayer grating based on the metrology metric.

17. The spectroscopic metrology system of claim 1 , wherein the test layer comprises:
at least one of hafnium dioxide, hafnium silicate, nitride hafnium silicate, or zirconium silicate.

18. The spectroscopic metrology system of claim 1 , wherein the spectroscopic metrology tool comprises:
an illumination source;
one or more illumination elements configured to direct an illumination beam from the illumination source to the multilayer grating including two or more layers;
one or more collection elements configured to collect radiation emanating from the multilayer grating in response to the illumination beam; and
a detector configured to receive the collected radiation and provide the measured spectroscopic signal indicative of the collected radiation.

19. The spectroscopic metrology system of claim 18 , further comprising:
an atmospheric regulation chamber enclosing the spectroscopic tool to regulate an atmosphere surrounding components of the spectroscopic tool with a selected gas.

20. The spectroscopic metrology system of claim 19 , wherein the selected gas comprises:
a gas transparent to wavelengths in a range of 120 nanometers to 2500 nanometers.

21. The spectroscopic metrology system of claim 19 , wherein the selected gas comprises:
a gas transparent to wavelengths in a range of 120 nanometers to 300 nanometers.

22. The spectroscopic metrology system of claim 19 , wherein the selected gas comprises:
a gas transparent to wavelengths in a range of 150 nanometers to 193 nanometers.

23. The spectroscopic metrology system of claim 22 , wherein the illumination source is configured to generate the illumination beam with wavelengths in the range of approximately 150 nanometers to 193 nanometers.

24. The spectroscopic metrology system of claim 23 , wherein the illumination source comprises:
a laser-driven light source.

Assignees

• Kla Tencor Corp
• Kla Corp

Inventors

• Wang tianhan
• Rosenberg Aaron
• Hu Dawei
• Kuznetsov Alexander
• Nguyen Manh Dang
• Pandev Stilian
• Lesoine John
• Zhao Qiang
• Lee Liequan
• Chouaib Houssam
• Di ming
• Kaack Torsten R
• Shchegrov Andrei V
• Tan Zhengquan

Classifications

• G01N21/25 Primary

  Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands · CPC title

• G01N21/956

  Inspecting patterns on the surface of objects {(contactless testing of electronic circuits G01R31/308; testing currency G07D; manufacturing processes per se of semiconductor devices implementing a measuring step H10P74/20)} · CPC title

• G01J2003/2836

  Programming unit, i.e. source and date processing · CPC title

• G01N21/8851

  Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges (G01N21/8806 and G01N21/93 - G01N21/95692 take precedence; optical measurement of dimensions G01B11/00; optical scanning G02B26/10; image transformation G06T3/00; computerised image enhancement G06T5/00; image processing per se for flaw detection G06T7/0002) · CPC title

• G01N21/8422

  Investigating thin films, e.g. matrix isolation method · CPC title