Electron microscope and electron bean inspection system.

Abstract

While an image obtained by a general electron microscope is affected by the shape and material of an object specimen, an image obtained from mirror electrons is affected by the shape of an equipotential surface on which the mirror electrons are reflected, thereby the image interpretation is complicated. A mirror electron microscope of the present invention is provided with the following means for controlling a reflecting plane of the mirror electrons according to the structure of an object pattern to be measured or a concerned defect.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a configuration of a mirror electron microscope in a first embodiment of the present invention;

FIG. 2 is a configuration of a mirror electron microscope in a second embodiment of the present invention;

FIG. 3 is a configuration of a mirror electron microscope in a third embodiment of the present invention;

FIG. 4 is a diagram for describing a distortion of an equipotential surface just above a solid pattern;

FIG. 5A is a diagram for describing a distortion of an equipotential surface, caused by a specimen potential;

FIG. 5B is a diagram for describing a distortion of an equipotential surface, caused by a specimen potential;

FIG. 6A is a diagram for describing an effect obtained by eliminating only a high energy part of an electron beam;

FIG. 6B is a diagram for describing an effect obtained by eliminating only a high energy part of an electron beam;

FIG. 6C is a diagram for describing an effect obtained by eliminating only a high energy part of an electron beam;

FIG. 6D is a diagram for describing an effect obtained by eliminating only a high energy part of an electron beam;

FIG. 7 is a diagram for describing an operation of an ExB deflector;

FIG. 8 is a diagram for describing a voltage distribution in deflection by an 8-pole type ExB deflector in the x deflection;

FIG. 9 is a diagram for describing a current distribution in deflection by the 8-pole type ExB deflector in the x deflection;

FIG. 10 is a cross sectional view of the 8-pole type ExB deflector;

FIG. 11 is a diagram for describing a relationship between the energy distribution and the energy level of a Schottky electron source;

FIG. 12 is a diagram for describing a relationship between the energy distribution and the energy level of a field emission electron source;

FIG. 13 is a diagram for describing a voltage distribution in deflection by the 8-pole type ExB deflector in the y direction;

FIG. 14 is a diagram for describing a current distribution in deflection by the 8-pole type ExB deflector in the y direction;

FIG. 15 is another configuration of a mirror electron microscope in the second embodiment of the present invention; and

FIG. 16 is a diagram for describing how an insulation specimen is illuminated with an electron beam from which only the high energy part is eliminated.

Claims

1. A mirror electron microscope, comprising: means for applying an accelerating voltage to an electron source;specimen voltage applying means for applying a specimen voltage to a stage for holding said specimen;an illuminating lens for illuminating an electron beam emitted from said electron source to said specimen as a planar illuminating electron beam having a two-dimensional extent;means for controlling a reflecting plane of said mirror electron beam reflected without coming into collision with said specimen; andmeans for converting said mirror electron beam to an image by projecting and magnifying said electron beam, then projecting and focusing said specimen image.

2. An inspection system, comprising: means for applying an accelerating voltage to an electron source;specimen voltage applying means for applying a specimen voltage to a stage for holding said specimen;an illuminating lens for illuminating an electron beam emitted from said electron source to said specimen as a planar illuminating electron beam having a two-dimensional extent;means for controlling a reflecting plane of said mirror electron beam reflected without coming into collision with said specimen;means for converting said mirror electron beam to an image by projecting and magnifying said electron beam, then projecting and focusing said specimen image; andmeans for inspecting the specimen from said image.

3. An inspection system, according to claim 2 further comprising: means for determining a defect by making a comparison between a plurality of images of one pattern.

4. The mirror electron microscope according to claim 1; wherein said means for controlling said reflecting plane of said mirror electron beam adjusts a height of said mirror electron beam reflecting plane with respect to a specimen surface by adjusting a relative voltage between said means for applying an accelerating voltage to an electron source and said specimen applying means.

5. The mirror electron microscope according to claim 4; wherein the height of said mirror electron beam reflecting plane is adjusted by controlling a relative voltage between said means for applying an accelerating voltage to an electron source and said specimen applying means according to a potential difference between said specimen and an electrode facing said specimen, as well as according to an electric field intensity between said specimen and said electrode facing said specimen, determined by a distance between said specimen and said electrode facing said specimen.

6. The mirror electron microscope or defect inspection system according to claim 1; wherein said means for controlling the height of said mirror electron beam reflecting plane also includes means for adjusting the energy distribution of said illuminating electron beam and controls a rate of said mirror electron beam reflecting from a certain height reflecting plane.

7. The mirror electron microscope according to claim 6; wherein said means for adjusting the energy distribution of said illuminating electron beam eliminates high energy components of said illuminating beam.

8. The mirror electron microscope according to claim 6; wherein the microscope or defect inspection system also includes means for controlling charging of an insulation specimen by eliminating high energy components of said illuminating electron beam.

9. The mirror electron microscope according to claim 6; wherein said means for adjusting the energy distribution of said illuminating beam eliminates low energy components of said illuminating beam.

10. The mirror electron microscope according to claim 6; wherein said means for adjusting the energy distribution of said illuminating beam illuminates an electron beam within a specific range of energy of said illuminating beam.

11. The mirror electron microscope according to claim 1; wherein said mirror electron beam reflecting plane is controlled on the basis of a plane on which electrons having the maximum energy in said illuminating electron beam is reflected.

12. The mirror electron microscope according to claim 1; wherein said mirror electron beam reflecting plane is controlled on the basis of a plane on which an electron beam is reflected with an energy obtained in a section of said illuminating electron beam, which has an energy value almost equal to the maximum.

13. The mirror electron microscope according to claim 1; wherein said mirror electron beam reflecting plane is controlled on the basis of a plane on which an electron beam up to a certain rate in said illuminating electron beam is reflected.

14. The mirror electron microscope according to claim 1; wherein said mirror electron beam reflecting plane is controlled according to a type of said specimen.

15. The inspection system according to claim 2; wherein said mirror electron beam reflecting plane is controlled according to an object defect.

16. A mirror electron microscope, comprising: an electron source;means for illuminating an area beam on a specimen with an illuminating lens system including an electron gun lens for accelerating and focusing an illuminating electron beam emitted from said electron source, a condenser lens, and an objective lens;means for magnifying and projecting a mirror electron beam reflected without coming into collision with a specimen with said objective lens, an intermediate lens, and an imaging lens; andmeans for separating said mirror electron beam from said illuminating electron beam with a separator;wherein said mirror electron microscope further includes means for selecting an energy of said illuminating electron beam with an energy filter disposed near to a cross-over of said illuminating electron beam formed by said electron gun lens.

17. The mirror electron microscope according to claim 16; wherein said mirror electron microscope further includes means for easing or canceling the energy dispersion of said illuminating electron beam caused by said energy filter with the energy dispersion caused by said separator.

18. The mirror electron microscope according to claim 17; wherein said mirror electron microscope further includes means for adjusting the direction of deflection by said energy filter on the basis of the direction of deflection by said separator.

19. The mirror electron microscope according to claim 18; wherein said mirror electron microscope further includes means for adjusting the direction of deflection by said energy filter on the basis of the intensity of excitation of a condenser lens disposed between said energy filter and said separator.

20. The mirror electron microscope according to claim 16; wherein said energy filter and said separator are ExB filters in which a magnetic field and an electric field cross each other.

21. The inspection system according to claim 2; wherein said means for controlling said reflecting plate of said mirror electron beam adjusts a height of said mirror electron beam reflecting plane with respect to a specimen surface by adjusting a relative voltage between said means for applying an accelerating voltage to an electron source and said specimen applying means.

22. The inspection system according to claim 21; wherein the height of said mirror electron beam reflecting plane is adjusted by controlling a relative voltage between said means for applying an accelerating voltage to an electron source and said specimen applying means according to a potential difference between said specimen and an electrode facing said specimen, as well as according to an electric field intensity between said specimen and said electrode facing said specimen, determined by a distance between said specimen and said electrode facing said specimen.

23. The inspection system according to claim 2; wherein said means for controlling the height of said mirror electron beam reflecting plane also includes means for adjusting the energy distribution of said illumination electron beam and controls a rate of said mirror electron beam reflecting from a certain height reflecting plane.

24. The inspection system according to claim 23; Wherein said means for adjusting the energy distribution of said illuminating electron beam eliminates high energy components of said illuminating beam.

25. The inspection system according to claim 23; wherein the microscope or defect inspection system also includes means for controlling charging of an insulation specimen by eliminating high energy components of said illuminating electron beam.

26. The inspection system according to claim 23; wherein said means for adjusting the energy distribution of said illuminating beam eliminates low energy components of said illuminating beam.

27. The mirror electron microscope according to claim 23; wherein said means for adjusting the energy distribution of said illuminating beam illuminates an electron beam within a specific range of energy of said illuminating beam.

28. The inspection system according to claim 2; wherein said mirror electron beam reflecting plane is controlled on the basis of a plane on which electrons having the maximum energy in said illuminating electron beam is reflected.

29. The inspection system according to claim 2; wherein said mirror electron beam reflecting plane is controlled on the basis of a plane on which an electron beam is reflected with an energy obtained in a section of said illuminating electron beam, which has an energy value almost equal to the maximum.

30. The inspection system according to claim 2; wherein said mirror electron beam reflecting plane is controlled on the basis of a plane on which an electron beam up to a certain rate in said illuminating electron beam is reflected.

31. The inspection system according to claim 2; wherein said mirror electron beam reflecting plane is controlled according to a type of said specimen.