Metrology Methods, Metrology Apparatus and Device Manufacturing Method

• US 20160282282A1
• Filed: 03/24/2016
• Published: 09/29/2016
• Est. Priority Date: 03/25/2015
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV), RWTH Aachen University
• Inventors: DANYLYUK, Serhiy, QUINTANILHA, Richard
• Granted Patent: US 10,067,074 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01N 2021/95676 Masks, reticles, shadow masks
• CPC Class Codes: G01N 21/8806 Specially adapted optical and illumination features
• 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 7/2004 characterised by the use of a particular light source, e.g. fluorescent lamps or deep UV light
• CPC Class Codes: G03F 7/70625 Dimensions, e.g. line width, critical dimension [CD], profile, sidewall angle or edge roughness
• CPC Class Codes: G06F 18/00 Pattern recognition

Abstract

A lithographic manufacturing system produces periodic structures with feature sizes less than 10 nm and a direction of periodicity (D). A beam of radiation (1904) having a range of wavelengths in the EUV spectrum (1-100 nm or 1-150 nm) is focused into a spot (S) of around 5 μm diameter. Reflected radiation (1908) is broken into a spectrum (1910) which is captured (1913) to obtain a target spectrum signal (ST). A reference spectrum is detected (1914) to obtain a reference spectrum signal (SR). Optionally a detector (1950) is provided to obtain a further spectrum signal (SF) using radiation diffracted at first order by the grating structure of the target. The angle of incidence (α) and azimuthal angle (φ) are adjustable. The signals (ST, SR, SF) obtained at one or more angles are used to calculate measured properties of the target, for example CD and overlay.

Claims

1. A method of measuring a property of a structure manufactured by a lithographic process, the method comprising:

(a) irradiating a periodic structure with a beam of radiation along an irradiation direction, the periodic structure having been formed by said lithographic process on a substrate and having a periodicity in at least a first direction, the radiation comprising a plurality of wavelengths in the range of 1-100 nm, the irradiation direction being greater than 2°

from a direction parallel to the substrate;

(b) detecting a spectrum of radiation reflected by the periodic structure, and

(c) processing signals representing the detected spectrum to determine a property of the periodic structure.

4. The method as claimed in claim 1 wherein the irradiation direction relative to a direction parallel to the substrate is adjusted prior to detecting said spectrum and a diameter of the beam of radiation is adjusted correspondingly to adjust the extent of beam when projected onto the periodic structure.

8. The method as claimed in claim 1, wherein an illumination system used to generate the beam of radiation is housed in a vacuum environment and the substrate is held in a low-pressure gaseous environment, the low-pressure gaseous environment being defined by a housing that is openable to load and unload new substrates without disturbing the vacuum environment of the illumination system.

9. The method as claimed in claim 1, wherein a detection system used to detect the spectrum of the reflected radiation is housed in a vacuum environment and the substrate is held in a low-pressure gaseous environment, the low-pressure gaseous environment being defined by a housing that is openable to load and unload new substrates without disturbing the vacuum environment of the detection system.

10. The method as claimed in claim 1, wherein the irradiation direction defines a non-zero azimuthal angle relative to the first direction, when projected onto a plane of the substrate.

13. The method as claimed in claim 1, wherein step (b) further includes detecting a non-zero diffraction order of radiation diffracted by the periodic structure, the non-zero diffraction order being spread into a spectrum by the periodic structure.

14. The method as claimed in claim 1, wherein said property is asymmetry.

16. The method as claimed in claim 13, wherein said wherein steps (a) and (b) are performed at least twice, with the periodic structure rotated 0°

and 180°

about a normal axis, and wherein in step (c) signals representing the spectrum of the non-zero diffraction order under 0° and

180°

rotation are used together to determine asymmetry of the periodic structure.

17. The method as claimed in claim 1, wherein steps (a) and (b) are repeated using different irradiation directions and wherein in step (c) signals representing the spectrum of reflected radiation detected using a plurality of different irradiation angles are used together to determine the property of the periodic structure.

18. The method as claimed in claim 1, wherein the step (c) includes defining a parameterized model of the periodic structure and using the model to perform performing mathematical reconstruction of the structure based on the detected reflected radiation.

2-3. -3. (canceled)

5-7. -7. (canceled)

11-12. -12. (canceled)

15. (canceled)

19. (canceled)

20. A metrology apparatus for use in measuring performance of a lithographic process, the apparatus comprising:

an irradiation system for generating a beam of radiation, the radiation comprising a plurality of wavelengths in the range of 1-100 nm;

a substrate support operable with the irradiation system for irradiating a periodic structure formed on the substrate with radiation along an irradiation direction, the irradiation direction being greater than 2°

from a direction parallel to the substrate; and

a detection system for detecting a spectrum of radiation reflected by the periodic structure.

23. The apparatus as claimed in claim 20, wherein the irradiation direction relative to a direction parallel to the substrate is adjustable and a diameter of the beam of radiation is adjustable correspondingly to adjust the extent of beam when projected onto the periodic structure.

27. The apparatus as claimed in claim 20, wherein an illumination system used to generate the beam of radiation is housed in a vacuum environment and the substrate is held in a low-pressure gaseous environment, the low-pressure gaseous environment being defined by a housing that is openable to load and unload new substrates without disturbing the vacuum environment of the illumination system.

28. The apparatus as claimed in claim 20, wherein a detection system used to detect the spectrum of the reflected radiation is housed in a vacuum environment and the substrate is held in a low-pressure gaseous environment, the low-pressure gaseous environment being defined by a housing that is openable to load and unload new substrates without disturbing the vacuum environment of the detection system.

29. The apparatus as claimed in claim 20, wherein the irradiation direction defines a non-zero azimuthal angle relative to the first direction, when projected onto a plane of the substrate, and the azimuthal angle is adjustable without demounting the substrate.

30. The apparatus as claimed in claim 20, further comprising a detector for detecting a non-zero diffraction order of radiation diffracted by the periodic structure, the non-zero diffraction order being spread into a spectrum by the periodic structure.

31. The apparatus as claimed in claim 20, wherein the substrate support is adapted to receive semiconductor wafers from an automated wafer handler.

32. The apparatus as claimed in claim 20, further comprising a processing system for processing signals representing the detected reflected radiation to determine a property of the periodic structure,

21-22. -22. (canceled)

24-26. -26. (canceled)

33. A device manufacturing method comprising:

transferring a pattern from a patterning device onto a substrate using a lithographic process, the pattern defining at least one periodic structure;

measuring one or more properties of the periodic structure to determine a value for one or more parameters of the lithographic process; and

applying a correction in subsequent operations of the lithographic process in accordance with the measured property,

wherein the step of measuring the properties of the periodic structure includes measuring a property by a method comprising;

irradiating a periodic structure with a beam of radiation along an irradiation direction, the periodic structure having been formed by said lithographic process on a substrate and having a periodicity in at least a first direction, the radiation comprising a plurality of wavelengths in the range of 1-100 nm, the irradiation direction being greater than 2°

from a direction parallel to the substrate;

detecting a spectrum of radiation reflected by the periodic structure, and

processing signals representing the detected spectrum to determine a property of the periodic structure.

34. (canceled)

35. A method of measuring a property of a structure manufactured by a lithographic process, the method comprising:

(a) irradiating a periodic structure with a beam of radiation along an irradiation direction, the periodic structure having been formed by said lithographic process on a substrate and having a periodicity in at least a first direction, the radiation comprising a plurality of wavelengths in the range of 1-100 nm, the irradiation direction being greater than 2°

from a direction parallel to the substrate;

(b) detecting a spectrum of radiation diffracted by the periodic structure, the non-zero diffraction order being spread into said spectrum by the periodic structure reflected by the periodic structure; and

,

(c) processing signals representing the detected spectrum to determine a property of the periodic structure.

36-41. -41. (canceled)