Lateral shift measurement using an optical technique

• US 20060102830A1
• Filed: 11/14/2005
• Published: 05/18/2006
• Est. Priority Date: 09/19/2000
• Status: Active Grant

• Current Assignee: Nova Ltd.
• Original Assignee: Nova Measuring Instruments Limited (Honeywell International Inc.)
• Inventors: Brill, Boaz, Finarov, Moshe, Scheiner, David
• Granted Patent: US 7,122,817 B2
• Time in Patent Office: Days
• US Class Current: 250/225
• CPC Class Codes: G01B 11/14 for measuring distance or clearance between spaced objects or spaced apertures G01B11/26 takes precedence; rangefinders G01C3/00
• CPC Class Codes: G01B 11/27 for testing the alignment of axes means for centering or aligning a light guide within a ferrule G02B6/3834
• CPC Class Codes: G01N 21/4788 Diffraction for sizing particles G01N15/0205
• CPC Class Codes: G01N 21/9501 Semiconductor wafers manufacturing processes per se of semiconductor devices implementing a measuring step H01L22/10
• CPC Class Codes: G01N 21/956 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 H01L22/10
• CPC Class Codes: G03F 7/70633 Overlay, i.e. relative alignment between patterns printed by separate exposures in different layers, or in the same layer in multiple exposures or stitching
• 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

Alignment of layers during manufacture of a multi-layer sample is controlled by applying optical measurements to a measurement site in the sample. The measurement site includes two diffractive structures located one above the other in two different layers, respectively. The optical measurements comprise at least two measurements with different polarization states of incident light, each measurement including illuminating eh measurement site so as to illuminate one of the diffractive structures through the other. The diffraction properties of the measurement site are indicative of a lateral shift between eth diffractive structures. The diffraction properties detected are analyzed for the different polarization states of the incident light to determine an existing lateral shift between the layers.

Claims

1. A method for controlling layers alignment while manufacturing a multi-layer sample, the method comprising:

applying optical measurements to a measurement site in the sample, the measurement site including two diffractive structures located one above the other in two different layers, respectively, said optical measurements comprising at least two measurements with different polarization states of incident light, each measurement including illuminating the measurement site thereby illuminating one of the diffractive structures through the other, and detecting diffraction properties of the measurement site indicative of a lateral shift between the diffractive structures;

analyzing the diffraction properties detected for the different polarization states of the incident light to determine an existing lateral shift between the layers.

2. The method of claim 1, wherein the optical measurements include normal incidence polarized spectrophotometry.

3. The method of claim 2, comprising measuring the normal incidence reflectivity spectrum of the measurement site with the at least two different polarization states defined by different polarization directions of the incident light relative to gratings defined by the diffractive structures.

4. The method of claim 3, wherein the polarization states include TM and TE polarization modes of the incident light relative to the grating orientation.

5. The method of claim 1, wherein the optical measurements include at least one of spectral ellipsometry and angular scatterometry.

6. The method of claim 1, further comprising:

providing at least one additional site including two regions located one above the other in two different layers, respectively, said regions containing diffractive structures;

applying optical measurements to said at least one additional site by illuminating said additional site with electromagnetic radiation and detecting diffraction efficiency of radiation diffracted from the structures, and analyzing the diffraction efficiencies obtained in said sites to determine an existing lateral shift between the layers.

7. The method of claim 1, wherein the diffractive structures located in two different layers of the measurement site are shifted with respect to each other along the X-axis by a distance (+Δ

X).

8. The method of claim 6, wherein the diffractive structures located in two different layers of the measurement site are shifted with respect to each other along the X-axis by a distance (+Δ

X).

9. The method of claim 8, wherein the diffractive structures located in two different layers of the additional site are shifted with respect to each other along the X-axis by a distance (−

Δ

X).

10. The method of claim 7 further comprising:

providing additional sites including regions containing diffractive structures in one of the layers.

11. The method of claim 8 wherein the diffractive structures located in two different layers of the additional sites are shifted with respect to each other along the X-axis by a distance (−

Δ

X±

NΔ

x), wherein Δ

x<

<

Δ

X and N is an integer number.

12. The method of claim 1 wherein said detecting of the diffraction properties indicative of a lateral shift between the diffractive structures comprising measuring a diffraction efficiency of radiation diffracted from the diffractive structures as a function of wavelength.

13. The method of claim 1 wherein said detecting of the diffraction properties indicative of a lateral shift between the diffractive structures comprising measuring a diffraction efficiency of radiation diffracted from the diffractive structures as a function of angle of incidence.

14. The method of claim 1 wherein said detecting of the diffraction properties indicative of a lateral shift between the diffractive structures comprising measuring a diffraction efficiency of radiation diffracted from the diffractive structures as a function of angle of reflection.

15. The method of claim 1 wherein said detecting of the diffraction properties indicative of a lateral shift between the diffractive structures comprising measuring a diffraction efficiency of radiation diffracted from the diffractive structures as a function of angle of incidence and angle of reflection.

16. The method of claim 1 wherein said detecting the diffraction properties indicative of a lateral shift between the diffractive structures comprising measuring a diffraction efficiency of radiation diffracted from the diffractive structures as a function of change of amplitude and phase of the diffracted light.

17. The method of claim 6, wherein at least one of the additional sites comprises the diffractive structures at essentially right angle to the diffractive structures of the measurement site.

18. The method of claim 1 wherein the illuminating of the site with electromagnetic radiation comprises illuminating the site with more than two different states of polarization of the incident light.

19. The method of claim 1 wherein patterns of the diffractive structures is two-dimensional.

20. The method of claim 19 wherein a period of the two-dimensional pattern is different along the X-axis and Y-axis.

21. The method of claim 1 wherein said multi-layer sample is a semiconductors wafer.