SPECIMEN OBSERVATION METHOD AND DEVICE, AND INSPECTION METHOD AND DEVICE USING THE METHOD AND DEVICE

• US 20110155905A1
• Filed: 04/10/2009
• Published: 06/30/2011
• Est. Priority Date: 04/11/2008
• Status: Active Grant

• Current Assignee: Ebara Corporation
• Original Assignee: Ebara Corporation
• Inventors: Kimura, Norio, Terao, Kenji, Naito, Yoshihiko, Murakami, Takeshi, Watanabe, Kenji, Hatakeyama, Masahiro
• Granted Patent: US 8,937,283 B2
• Time in Patent Office: Days
• US Class Current: 250/307
• CPC Class Codes: H01J 2237/24475 Scattered electron detectors
• CPC Class Codes: H01J 2237/24585 Other variables, e.g. energy, mass, velocity, time, temperature
• CPC Class Codes: H01J 2237/24592 Inspection and quality control of devices
• CPC Class Codes: H01J 2237/2805 Elastic scattering
• CPC Class Codes: H01J 2237/2806 Secondary charged particle
• CPC Class Codes: H01J 2237/2817 Pattern inspection
• CPC Class Codes: H01J 37/22 Optical or photographic arrangements associated with the tube using a CRT for the display of the image in a scanning electron microscope H01J37/28; observing the object or the point of impact on the object in tubes for the localised treatment of materials H01J37/3007
• CPC Class Codes: H01J 37/244 Detectors; Associated components or circuits therefor
• CPC Class Codes: H01J 37/28 with scanning beams H01J37/268, H01J37/292, H01J37/2955 take precedence
• CPC Class Codes: H01J 37/29 Reflection microscopes
• 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 technique capable of improving the ability to observe a specimen using an electron beam in an energy region which has not been conventionally given attention is provided. This specimen observation method comprises: irradiating the specimen with an electron beam; detecting electrons to be observed which have been generated and have obtained information on the specimen by the electron beam irradiation; and generating an image of the specimen from the detected electrons to be observed. The electron beam irradiation comprises irradiating the specimen with the electron beam with a landing energy set in a transition region between a secondary emission electron region in which secondary emission electrons are detected and a mirror electron region in which mirror electrons are detected, thereby causing the secondary emission electrons and the mirror electrons to be mixed as the electrons to be observed. The detection of the electrons to be observed comprises performing the detection in a state where the secondary emission electrons and the mirror electrons are mixed. Observation and inspection can be quickly carried out for a fine foreign material and pattern of 100 nm or less.

Claims

1. A specimen observation method for observing a specimen using an electron beam, the specimen observation method comprising:

irradiating the specimen with an electron beam;

detecting electrons to be observed which have been generated and have obtained information on the specimen by the electron beam irradiation; and

generating an image of the specimen from the detected electrons to be observed,

wherein the electron beam irradiation comprises irradiating the specimen with the electron beam with a landing energy set in a transition region between a secondary emission electron region in which secondary emission electrons are detected and a mirror electron region in which mirror electrons are detected, thereby causing the secondary emission electrons and the mirror electrons to be mixed as the electrons to be observed, and

wherein the detection of the electrons to be observed comprises performing the detection in a state where the secondary emission electrons and the mirror electrons are mixed.

2. The specimen observation method according to claim 1, wherein the generation of an image comprises generating an image of a foreign material present on a surface of the specimen.

3. The specimen observation method according to claim 1, wherein the generation of an image comprises generating an image of the specimen on which an insulating area and a conductive area are formed.

4. The specimen observation method according to claim 1, wherein the generation of an image comprises generating an image of a pattern formed on the specimen.

5. The specimen observation method according to claim 1, wherein the generation of an image comprises generating an image of the specimen in which a plurality of films are layered.

6. A specimen observation device for observing a specimen using an electron beam, the specimen observation device having:

a stage for placing the specimen thereon;

a primary optical system for irradiating the specimen with an electron beam;

a secondary optical system for detecting electrons to be observed which have been generated and have obtained information on the specimen by the electron beam irradiation; and

an image processor for generating an image of the specimen from the detected electrons to be observed,

wherein the primary optical system irradiates the specimen with the electron beam with a landing energy set in a transition region between a secondary emission electron region in which secondary emission electrons are detected and a mirror electron region in which mirror electrons are detected, thereby causing the secondary emission electrons and the mirror electrons to be mixed as the electrons to be observed, and

wherein the secondary optical system performs the detection in a state where the secondary emission electrons and the mirror electrons are mixed.

7. An electron beam inspection method for irradiating a specimen surface with an imaging electron beam having a predetermined irradiation area, detecting reflected electrons by means of a detector, and thereby acquiring an image of the specimen surface and of a foreign material on the specimen surface, the electron beam inspection method comprising:

charging the foreign material by irradiation with a charging electron beam and forming around the foreign material a potential distribution different from that of the specimen surface; and

detecting the electrons which are reflected from the foreign material by the imaging electron beam irradiation and reach the detector through a path bent by the effect of the potential distribution, and acquiring a magnified image of the foreign material in which the magnification for the foreign material is increased more than the magnification for the specimen surface.

8. The electron beam inspection method according to claim 7,

wherein the step of charging the foreign material comprises negatively charging up the foreign material by the charging electron beam irradiation, and

wherein the step of acquiring the magnified image comprises setting the landing energy of the imaging electron beam to 10 eV or less, detecting mirror electrons reflected immediately in front of the foreign material, and acquiring the magnified image of the foreign material.

9. The electron beam inspection method according to claim 7, wherein the step of acquiring the magnified image comprises setting the landing energy of the imaging electron beam to 10 eV or more, detecting secondary emission electrons reflected by being emitted from the foreign material, and acquiring the magnified image of the foreign material.

10. The electron beam inspection method according to claim 7, wherein the landing energy of the imaging electron beam is set to a landing energy which:

is in a landing energy range in which electrons reflected from the specimen surface are a mixture of mirror electrons and secondary emission electrons, or only secondary emission electrons;

is in a landing energy range in which electrons reflected from the foreign material are a mixture of mirror electrons and secondary emission electrons; and

maximizes the difference in gray level between the image of the specimen surface and the magnified image of the foreign material.

11. An electron beam inspection device comprising:

a stage for placing a specimen thereon;

a primary optical system for generating an electron beam having a predetermined irradiation area and for emitting the electron beam toward the specimen; and

a secondary optical system, having a detector for detecting electrons reflected from the specimen, for acquiring an image of a predetermined visual field area on the specimen,

wherein the primary optical system charges the foreign material by irradiation with a charging electron beam to cause the potential distribution of the foreign material to be different from that of a specimen surface, and then irradiates the specimen with an imaging electron beam, and

wherein the secondary optical system detects electrons which are reflected from the foreign material and reach the detector through a path bent by the effect of the potential distribution, and acquires a magnified image of the foreign material in which the magnification for the foreign material is increased more than the magnification for the specimen surface.

12. The electron beam inspection device according to claim 11,

wherein the primary optical system charges up the foreign material by irradiation with the charging electron beam and then irradiates the specimen with the imaging electron beam with a landing energy of 10 eV or less, and

wherein the secondary optical system detects mirror electrons reflected immediately in front of the foreign material by means of the detector and acquires the magnified image of the foreign material.

13. The electron beam inspection device according to claim 11,

wherein the primary optical system sets the landing energy of the imaging electron beam to 10 eV or more, and

wherein the secondary optical system detects secondary emission electrons which are emitted from the foreign material and reach the detector and acquires the magnified image of the foreign material.

14. A specimen observation device comprising:

an electron beam source for irradiating a specimen surface on which an insulating area and a conductive area are formed with an imaging electron beam;

an E×

B filter for directing electrons which have obtained structural information on the specimen surface by the irradiation with the imaging electron beam, wherein the E×

B filter directs the electrons according to the speed of the electrons which move in a direction opposite to an incident direction of the imaging electron beam and using electric and magnetic fields;

a detector for detecting the electrons directed by the E×

B filter and acquiring an image of the specimen surface from the detected electrons; and

an irradiation energy setting unit for setting the irradiation energy of the imaging electron beam in a transition region in which the electrons include both mirror electrons and secondary electrons.

15. The specimen observation device according to claim 14, having:

an NA adjustment aperture having a plurality of types of NA apertures different in aperture diameter; and

an NA adjustment aperture moving mechanism for moving the NA adjustment aperture,

wherein a contrast of the image is optimized by adjusting the position of the NA aperture and the aperture diameter so that the electrons having structural information on the conductive area go through the NA aperture.

16. A specimen observation method comprising:

irradiating a specimen surface on which an insulating area and a conductive area are formed with an imaging electron beam; and

detecting electrons which have obtained structural information on the specimen surface and acquiring an image of the specimen surface,

wherein the imaging electron beam with which the specimen surface is irradiated has an irradiation energy in a transition region in which the electrons include both mirror electrons and secondary electrons.

17. A specimen observation method for observing a pattern of a specimen using an electron beam, the specimen observation method comprising:

irradiating the specimen with an electron beam;

detecting mirror electrons generated by the electron beam irradiation; and

generating an image of the specimen from the detected mirror electrons,

wherein the electron beam irradiation comprises irradiating the specimen with the electron beam with a landing energy adjusted so that when a hollow pattern with edges on both sides is irradiated with the electron beam, irradiation electrons turn around at the hollow pattern to become mirror electrons.

18. The specimen observation method according to claim 17, wherein the landing energy is set in a region in which the mirror electrons and secondary emission electrons are mixed.

19. A specimen observation device comprising:

a stage for placing a specimen thereon;

a primary optical system for irradiating the specimen with an electron beam;

a secondary optical system for detecting mirror electrons generated by the electron beam irradiation; and

an image processor for generating an image of the specimen from the detected mirror electrons,

wherein the primary optical system irradiates the specimen with the electron beam with a landing energy adjusted so that when a hollow pattern with edges on both sides is irradiated with the electron beam, irradiation electrons turn around at the hollow pattern to become mirror electrons.

20. The specimen observation device according to claim 19, wherein the primary optical system irradiates with the electron beam with the landing energy set in a region in which the mirror electrons and secondary emission electrons are mixed.

21. The specimen observation device according to claim 19, wherein the secondary optical system comprises:

an aperture placed between the specimen and a detector for the mirror electrons; and

an aperture adjustment mechanism for adjusting at least one of the size, position, and shape of the aperture according to the mirror electrons going through the aperture.

22. A specimen inspection device comprising the specimen observation device according to claim 19, wherein a pattern of the specimen is inspected by using the image of the specimen generated from the mirror electrons by the image processor.

23. An inspection method for a film-coated substrate, the film-coated substrate having a substrate on which a three-dimensional shape is formed and a plurality of films comprising different materials layered and formed on the substrate, the film-coated substrate including a structure in which a lower layer film is exposed due to a top layer film being removed, the film-coated substrate inspection method comprising:

irradiating a surface of the film-coated substrate with a charged particle beam with a landing energy set so as to cause the surface potential to vary among the top layer film located immediately above an area where the three-dimensional shape is formed on the substrate, the top layer film located immediately above an area where no three-dimensional shape is formed on the substrate, and the lower layer film;

detecting electrons which have acquired information on the surface potential of the film-coated substrate, and acquiring a potential contrast of the surface of the film-coated substrate; and

simultaneously detecting the shape of the top layer film and the three-dimensional shape formed on the substrate, based on the potential contrast.

24. An inspection method for a film-coated substrate for detecting the shapes of a plurality of films comprising different materials layered and formed on the substrate, the film-coated substrate inspection method comprising:

irradiating a surface of the film-coated substrate with a charged particle beam with a landing energy set so as to cause the surface potential of the film-coated substrate to vary depending on differences in type and thickness among the materials of the films;

detecting electrons which have acquired information on the surface potential of the film-coated substrate, and acquiring a potential contrast of the surface of the film-coated substrate; and

detecting the shapes of the plurality of films based on the potential contrast.

25. An inspection device for a film-coated substrate, the film-coated substrate having a substrate on which a three-dimensional shape is formed and a plurality of films comprising different materials layered and formed on the substrate, the film-coated substrate including a structure in which a lower layer film is exposed due to a top layer film being removed, the film-coated substrate inspection device comprising:

a charged particle irradiation unit for irradiating a surface of the film-coated substrate with a charged particle beam with a landing energy set so as to cause the surface potential to vary among the top layer film located immediately above an area where the three-dimensional shape is formed on the substrate, the top layer film located immediately above an area where no three-dimensional shape is formed on the substrate, and the lower layer film;

a detector for detecting electrons which have acquired information on the surface potential of the film-coated substrate, and acquiring a potential contrast of the surface of the film-coated substrate; and

an arithmetic unit for simultaneously detecting the shape of the top layer film and the three-dimensional shape formed on the substrate, based on the potential contrast.

26. An inspection device for a film-coated substrate for detecting the shapes of a plurality of films comprising different materials layered and formed on the substrate, the film-coated substrate inspection device having:

a charged particle irradiation unit for irradiating a surface of the film-coated substrate with a charged particle beam with a landing energy set so as to cause the surface potential of the film-coated substrate to vary depending on differences in type and thickness among the materials of the films;

an imaging device for detecting electrons which have acquired information on the surface potential of the film-coated substrate, and acquiring a potential contrast of the film-coated substrate; and

an arithmetic unit for detecting the shapes of the plurality of films based on the potential contrast.