Method and apparatus for measurements of patterned structures

• US 7,187,456 B2
• Filed: 02/08/2005
• Issued: 03/06/2007
• Est. Priority Date: 03/18/1998
• Status: Expired due to Term

• Current Assignee: Nova Ltd.
• Original Assignee: Nova Measuring Instruments Limited (Honeywell International Inc.)
• Inventors: Scheiner, David, Machavariani, Vladimir
• Primary Examiner(s): Lee; Hwa (Andrew)
• Assistant Examiner(s): Punnoose; Roy M.
• Application Number:
  US11/053,254
• Publication Number:
  US 20050146729A1
• Time in Patent Office: 756 Days
• Field of Search: 356/630, 356/632, 356/635, 356/639, 356/319, 356/601, 356/625, 250/372, 250/341.1
• US Class Current: 356/630
• CPC Class Codes: G01B 11/02 for measuring length, width or thickness G01B11/08 takes precedence
• CPC Class Codes: G01B 11/0625 with measurement of absorption or reflection
• CPC Class Codes: G01J 3/42 Absorption spectrometry; Double beam spectrometry; Flicker spectrometry; Reflection spectrometry beam switching arrangements G01J3/08
• CPC Class Codes: H01L 22/12 for structural parameters, e.g. thickness, line width, refractive index, temperature, warp, bond strength, defects, optical inspection, electrical measurement of structural dimensions, metallurgic measurement of diffusions electrical measurement of diffusions H01L22/14

Abstract

A method for measuring at least one desired parameter of a patterned structure having a plurality of features defined by a certain process of its manufacturing. The structure represents a grid having at least one cycle formed of at least two metal-containing regions spaced by substantially transparent regions with respect to incident light defining a waveguide. An optical model is provided, which is based on at least some of the features of the structure defined by a certain process of its manufacturing, and on the relation between a range of the wavelengths of incident radiation to be used for measurements and a space size between the two metal-containing regions in the grid cycle, and a skin depth of said metal. The model is capable of determining theoretical data representative of photometric intensities of light components of different wavelengths specularly reflected from the structure and of calculating said at least one desired parameter of the structure. A measurement area is located and spectrophotometric measurements are applied to the measurement area, by illuminating it with incident light of a preset substantially wide wavelength range. A light component substantially specularly reflected from the measurement area is detected, and measured data representative of photometric intensities of each wavelength within the wavelength range is obtained. The measured and theoretical data are analyzed and the optical model is optimized until the theoretical data satisfies a predetermined condition. Upon detecting that the predetermined condition is satisfied, said at least one parameter of the structure is calculated.

Claims

1. A method of optical measurements on a patterned structure having an array of spaced-apart metal-containing regions located within at least one substantially transparent layer, the method comprising:

a) providing an optical model, based on features of a structure having an array of spaced-apart metal-containing regions located within at least one substantially transparent layer, which features are defined by a certain process of the structure manufacturing, the optical model being configured for determining theoretical data representative of spectral characteristics of light returned from the structure and for calculating a thickness of the metal-containing region of the structure;

b) applying optical measurements to said patterned structure, by illuminating it with incident radiation of a preset substantially wide wavelength range, detecting light returned from the patterned structure, and obtaining measured data representative of spectral characteristics of the returned light within said wavelength range;

c) processing and analyzing the measured data using said theoretical data, to determine a thickness of the metal-containing region of the patterned structure under measurements.

2. The method according to claim 1, wherein said processing and analyzing comprises determining a relation between the measured data from the metal-containing regions and at least one substantially transparent layer.

3. The method according to claim 2, wherein said relation is indicative of the thickness of the metal-containing regions of the patterned structure.

4. The method according to claim 1, wherein said model is selected to have the thickness of the metal-containing regions of the patterned structure as a variable model parameter.

5. The method according to claim 1, wherein said structure is a semiconductor wafer structure.

6. The method according to claim 5, wherein said measured data is indicative of the thickness of the metal-containing regions comprising copper.

7. The method according to claim 6, wherein said measured data is indicative of the thickness of the metal-containing regions within multi-layer regions.

8. The method according to claim 1, wherein the optical model being representative of a polarazation effect due to interaction of the incident radiation with the metal-containing regions.

9. The method according to claim 8, wherein the detecting light returned from the optical model being representative of a polarization effect due to interaction of the incident radiation with the metal-containing regions.

10. The method according to claim 1, wherein the features of the structure, on which the optical model is based, comprise nominal values of the thickness parameters to be measured.

11. The method according to claim 1, wherein said processing and analyzing comprises:

comparing the theoretical data with the measured data and providing data indicative of the relation between the measured and theoretical data.

12. The method according to claim 1, wherein the optical measurements are applied to a test site representing a test pattern similar to that of the structure under measurements in design rules and layer stacks.

13. The method according to claim 1, wherein the uppermost layer is a layer to be removed during the manufacturing process.

14. The method according to claim 1, wherein said manufacturing process includes Chemical Mechanical Planarization (CMP).

15. The method according to claim 14, wherein the uppermost layer is a layer to be removed during the CMP.

16. The method of claim 1, utilizing a spectrometric measurement system integrated with a processing tools arrangement carrying out the manufacturing process.

17. The method of claim 1, for controlling the manufacturing process applied to the structure.

18. The method of claim 1, for controlling the manufacturing process applied to the structure using an integrated spectrometric measurement system.

19. The method of claim 14, for controlling the CMP process applied to the structure.

20. The method of claim 19, utilizing a spectrometric measurement system integrated with the CMP tools arrangement.

21. The method according to claim 9, wherein the optical model comprises features defined prior to the measurements.

22. The method according to claim 9, wherein the features of the structure, on which the optical model is based, comprise nominal values of the thickness parameters to be measured.

23. The method according to claim 9, wherein said processing and analyzing comprises:

comparing the theoretical data with the measured data and providing data indicative of the relation between the measured and theoretical data.

24. The method according to claim 9, wherein the uppermost layer is a layer to be removed during the manufacturing process.

25. The method according to claim 9, wherein said manufacturing process includes Chemical Mechanical Planarization (CMP).

26. The method according to claim 25, wherein the uppermost layer is a layer to be removed during the CMP.

27. An apparatus for optical measurements in a patterned structure having an array of spaced-apart metal-containing regions arranged within an insulator layer, the apparatus comprising:

a spectrometer for detecting a light response of a structure to incident light of a preset substantially wide wavelength range and for providing measured data representative of spectral characteristics of said light response within said wavelength range; and

a processor unit coupled to the spectrometer, the processor being operable for applying an optical model based on features of a structure having an array of spaced-apart metal-containing regions located within an insulator layer, said features being defined by a certain process of the structure manufacture, to determine theoretical data representative of spectral characteristics of light returned from the structure and for calculating a thickness parameter of the metal-containing region of the structure, and processing and analyzing the measured data, associated with the patterned structure, using the theoretical data and determining a thickness of the metal-containing region of said patterned structure under measurements.

28. The apparatus according to claim 27, wherein said spectrometer comprises a spectrometric detector and a variable aperture stop located in the optical path of light reaching the detector, the diameter of the aperture stop being variable in accordance with the pattern in the structure under measurements.

29. The apparatus according to claim 27, wherein said the processor unit comprising a pattern recognition software for locating the measurements.

30. The apparatus according to claim 27, wherein said spectrometer comprises a polarizer.