Electron beam microscope

Abstract

An electron beam microscope comprises an electron beam source 5, an objective lens 25, and an electron detector 37. The electron detector 37 includes a scintillator assembly 76, which is arranged between the electron beam source 5 and an object location 35 such that electrons 81 generated at the object 21 strike a scintillator body 77, which is formed from a scintillator material that generates light 83 upon contact with the incident electrons 81. The electron detector 37 further comprises a light detector 91 for detecting the light 83 generated by the scintillator body 77, and an optical element 87 having an optically effective surface 85, which is arranged between the scintillator assembly 76 and the object location 35 and is positioned in a beam path of the light 83 detected by the light detector 91 between the scintillator body 77 and the light detector 91.

Description

[0001] The invention relates to an electron beam microscope which has an electron detector.

[0002] A conventional electron beam microscope includes an electron beam source to generate an electron beam, a specimen holder to hold an object to be examined with the electron beam microscope, an objective lens to focus the electron beam on the object, and an electron detector to detect electrons generated by the electron beam on the object.

[0003] The electron detector comprises a converter that directly generates electrical signals or light from incident electrons, which is then detected to generate further electrical signals. Due to the configuration of the electron detector, for example, its geometric dimensions, and the need for additional components such as optical fibers and electrical conductors, its use is subject to constraints that, in some cases, prevent electrons from being detected at desired positions within the electron beam microscope.

[0004] For example, reference is made to the publications DE 11 2014 002 859 T5 and DE 10 2023 106 030 A1, which show scintillators that generate light with incident electrons, which is reflected by mirrors to light detectors that generate electrical signals.

[0005] It is desirable to obtain further configurations of electron detectors that expand the range of applications for electron detectors.

[0006] According to the invention, an electron beam microscope comprises an electron beam source to generate an electron beam, a specimen holder to hold an object at an object location on which the electron beam strikes, an objective lens arranged along a beam path of the electron beam between the electron source and the object location to focus the electron beam at the object location, and a first electron detector to detect electrons generated at the object.

[0007] The first electron detector comprises a scintillator array positioned along the electron beam path between the electron beam source and the object location such that the electrons generated at the object strike the scintillator body. The scintillator array includes a scintillator body made of a scintillator material that emits light upon contact with the electrons. The first electron detector further comprises a light detector to detect light generated by the scintillator body or the scintillator array and convert it into electrical signals. The first electron detector also includes an optical element having an optically effective surface positioned along the electron beam path between the scintillator array and the object location, such that the optically effective surface is located closer to the object location than the scintillator array.The optically effective surface is located in the path of the light detected by the light detector, between the scintillator assembly and the light detector. For the light generated by the scintillator to reach the light detector, at least a portion of it must first pass through the optically effective surface. Since the optically effective surface is located closer to the object than the scintillator, the light generated by the scintillator is directed towards the optically effective surface and thus towards the plane that intersects the electron beam path at the object orthogonally.

[0008] The scintillator assembly has an electron receiving surface onto which the electrons generated by the object strike the scintillator body. Furthermore, the scintillator assembly has a light-emitting surface through which the light generated by the scintillator material exits the assembly. The electron receiving surface and the light-emitting surface overlap at least partially.

[0009] The beam path between the scintillator array and the optically effective surface lies at least partially in a vacuum. Likewise, the beam path between the optically effective surface and the light detector lies at least partially in a vacuum. Along the beam path between the optically effective surface and the light detector, the measured distance between the scintillator array and the optically effective surface is, for example, 2 mm, 4 mm, or more. Along the beam path in a vacuum between the optically effective surface and the light detector, the measured distance between the optically effective surface and the light detector is, for example, 2 mm, 4 mm, or more.The scintillator assembly can include a light-guiding body in addition to the scintillator body, such that light generated by the scintillator body either exits the scintillator assembly directly to be detected, or first enters the light-guiding body before exiting it and the scintillator assembly to be detected. The light-guiding body can act as a support for the scintillator body if the scintillator body is particularly thin or is applied as a coating to the light-guiding body. The scintillator assembly can be wholly or partially coated with an electrically conductive layer, which prevents local electrical charging of the surface of the scintillator assembly. According to exemplary embodiments, the mirror surface is a curved surface.According to exemplary embodiments herein, an ellipsoid exists as a mathematical surface such that the mirror surface is adapted to parts of the ellipsoid and the maximum distance between the mirror surface and the ellipsoid is less than 5 mm or less than 3 mm. The ellipsoid as a mathematical surface is generated by rotating an ellipse about its major axis. In this process, the distance between the scintillator body and a focal point of the ellipsoid can be less than 3 mm.

[0010] According to other exemplary embodiments, a paraboloid exists as a mathematical surface such that the mirror surface is adapted to parts of the paraboloid and the maximum distance of the effective mirror surface from the paraboloid is less than 3 mm. The paraboloid as a mathematical surface is generated by rotating a parabola around its axis of symmetry.

[0011] According to exemplary embodiments, the optical element is a lens, and the optically effective surface is a lens surface at which the light detected by the light detector undergoes refraction. The lens surface can be formed by an electrically conductive layer that is transparent to the light generated by the scintillator body. Furthermore, the lens can have an optical axis that is inclined relative to the path of the electron beam and forms a minimum angle with it greater than 4° and, in particular, greater than 10°.

[0012] According to exemplary embodiments, the optically effective area is greater than 10 mm. 2 , and especially larger than 100 mm 2 .

[0013] According to further exemplary embodiments, the optical element has a recess through which the beam path of the electron beam extends, so that on the one hand the electron beam from the electron beam source to the object can pass through the optical element and on the other hand the electrons generated at the object can pass through the optical element towards the scintillator arrangement.

[0014] According to exemplary embodiments, the first light detector comprises a light guide which is arranged in the beam path of the light detected by the light detector between the optically effective surface and the light detector.

[0015] According to exemplary embodiments, the electron beam microscope comprises a second electron detector configured to detect electrons generated by the electron beam at the object that have a kinetic energy greater than an adjustable threshold. This second electron detector includes a converter configured to convert the electrons generated at the object and striking the converter into electrical or optical signals. The second electron detector further comprises a first electrode, a second electrode, a tube, and an insulator. The path of the electron beam directed at the object passes through the tube in its longitudinal direction. The tube is electrically conductive and serves to shield the electron beam passing through the tube from electric fields generated by the first and second electrodes outside the tube.The converter, the first electrode, and the second electrode each extend in planes oriented orthogonally to the electron beam path. The first electrode, the second electrode, and the converter are arranged in this order, spaced apart from one another. Electrons generated by the electron beam at the object and striking the converter first pass through the first electrode and then the second electrode before reaching the converter. The first and second electrodes can be formed from electrically conductive grids or meshes. An adjustable electrical potential can be applied to the second electrode by the electron microscope's control system. This potential defines the threshold of the electrons' kinetic energy that can be converted into optical or electrical signals by the converter.The electrical potentials of the first electrode and the converter can be the same, adjustable together, or adjustable independently. In particular, the electrical potentials of the first electrode and the converter can be equal to the electrical potential of the tube through which the electron beam passes. The insulator surrounds the tube along the path of the electron beam, at least between the first and second electrodes and between the second electrode and the converter, and is designed to prevent the uniform electric fields generated between the first and second electrodes and between the second electrode and the converter from being disturbed and distorted by the electrical potential of the tube through which the electron beam passes.

[0016] According to exemplary embodiments, the scintillator arrangement of the first electron detector is arranged along the electron beam path between the first electrode and the object location or between the second electrode and the object location. Viewed from the object location and in the direction of the beam path, the converter can overlap with the insulator. In this case, the converter, viewed from the object location and in the direction of the beam path, can be located outside the tube or overlap with the tube. This allows the first electron detector to detect electrons that would not be detectable without the presence of the first electron detector's converter in front of the insulator or in front of the tube.Without the converter of the first electron detector, the cross-sectional area of ​​the insulator forms a dead zone. Electrons generated by the electron beam at the object strike this dead zone, carrying information about the object's properties to its location, but would otherwise be undetectable. With the scintillator body of the first electron detector positioned in front of the insulator, these electrons become detectable by the first electron detector.

[0017] According to an example also disclosed herein, an electron beam microscope comprises an electron beam source to generate an electron beam, a specimen holder to hold an object at an object location on which the electron beam strikes, an objective lens to focus the electron beam at the object location, a first electron detector to detect electrons generated by the electron beam at the object, and the second electron detector described above.

[0018] The first electron detector includes a converter configured to convert electrons generated at the object into electrical or optical signals, with this converter being located in front of the insulator of the second electron detector from the perspective of the object.

[0019] According to the example, the converter of the first electron detector is formed by a semiconductor detector, which generates electrical signals through the electrons produced at the object and striking the converter.

[0020] According to exemplary embodiments, the electron beam microscope further comprises a beam tube having an electrically conductive inner lining into which the electron beam enters at a first end of the beam tube and from which the electron beam exits at a second end of the beam tube. The converter of the first electron detector is arranged between the first and second ends of the beam tube and within the beam tube. The converter of the second electron detector can also be arranged between the first and second ends of the beam tube and within the beam tube.

[0021] According to exemplary embodiments, the objective lens provides a focusing magnetic field for the electron beam. This focusing magnetic field has a maximum. This maximum can be located along the electron beam path between the first and second ends of the beam tube. Furthermore, the converter of the first electron detector can be located along the electron beam path between the electron beam source and this maximum.

[0022] An electron beam microscope comprising an electron beam source for generating an electron beam, a specimen holder for holding an object at a location on which the electron beam strikes, an objective lens for focusing the electron beam on the object, a first electron detector for detecting electrons generated on the object, and a second electron detector for detecting electrons generated on the object, can, according to another example, be configured such that the second electron detector includes a converter configured to convert electrons generated on the object, which strike an electron receiving surface of the converter, into electrical or optical signals.

[0023] The first electron detector can include a converter configured to convert electrons generated at the object, which strike an electron receiving surface of the converter, into light. The converter of the first electron detector can include a scintillator body, which provides the electron receiving surface of the converter and is formed from a scintillator material that reacts with the electrons generated at the object and striking the scintillator body to produce light.

[0024] In a plane that intersects the scintillator body of the first electron detector and is orthogonal to the electron beam path near the scintillator body, the following consideration can be made: in this plane, there is a point where the electron beam intersects the plane during operation. The scintillator body at least partially surrounds this point. This point can therefore be considered a center around which the scintillator body is arranged. For example, the scintillator body in this plane has the shape of an annulus, that is, the shape of a circular plate with a central hole. It is not necessary for the scintillator body to have a perfectly annular shape. The scintillator body can also have a shape with an edge near the center, which, for example, has a polygonal shape.Similarly, the scintillator body can have an edge located away from the center, which, for example, has a polygonal shape. Furthermore, the scintillator body need not extend completely and continuously around the center. Rather, it is possible for a single scintillator body to extend only over a portion of its circumference around the center. It is also possible for multiple scintillator bodies to be provided, each extending only over portions of its circumference around the center and arranged adjacent to one another in the circumferential direction around the center.

[0025] In the plane in which the observation is made, there is a region permeated by electrons generated by the electron beam at the object and striking the electron receiving surface of the second electron detector. This region lies outside the center of the scintillator body of the first electron detector, or, expressed in other words, the scintillator body is located between the center and the points in the plane where the electrons detected by the second electron detector permeate the plane. Or, put yet another way, a straight line connecting the center and each point in the plane where the electron detected by the second electron detector permeates the plane intersects the scintillator body.

[0026] For example, the first electron detector comprises an optical fiber and a light detector. The scintillator assembly has a light-emitting surface through which the light generated by the scintillator material can exit the assembly. The optical fiber has a light-entry surface through which the light exiting the scintillator assembly can enter the optical fiber. The optical fiber is configured to direct the light entering the optical fiber through the light-entry surface to the light detector.

[0027] For example, in the plane penetrating the scintillator body and oriented orthogonally to the beam path, the following can be observed: there are electrons generated at the object and detected by the second electron detector that penetrate the plane in a sub-region located between the light-exit surface of the scintillator assembly and the light-entry surface of the optical fiber. In other words, a volumetric region located between the light-exit surface and the light-entry surface is penetrated, on the one hand, by the light generated by the scintillator assembly of the first electron detector and detected by its light detector, and on the other hand, by the electrons generated at the object and detected by the second electron detector.

[0028] In exemplary embodiments, the light-emitting surface of the scintillator assembly is provided with an electrically conductive and transparent layer. In further exemplary embodiments, surfaces of the scintillator assembly that differ from the light-emitting surface are at least partially, i.e., partially or completely, provided with a light-reflecting layer, which is preferably electrically conductive. The coatings of the scintillator assembly are advantageously designed to be electrically conductive in order to prevent the formation of local electrical charges on the surface at locations where electrons may strike during operation of the electron beam microscope. These local charges could lead to electrical discharges or unintentionally influence the trajectories of the electron beam or the electrons to be detected.

[0029] Advantageously, portions of the scintillator array's surface that are not part of the light-emitting surface are provided with light-reflecting coatings to prevent light within the scintillator array from exiting in a direction that would not reach the light-entry surface of the optical fiber. The reflective coating causes such light to be reflected one or more times within the scintillator array, thus giving it the opportunity to reach the transparent light-emitting surface, allowing the light to strike the light-entry surface of the optical fiber and ultimately be detected by the light detector.

[0030] For example, the light-entry surface, as seen in the plane intersecting the scintillator body and orthogonal to the electron beam path, is concave. This reduces the proportion of light reflected at the light-entry surface and, through refraction, changes the direction of the light entering the optical fiber through the light-entry surface towards the light detector.

[0031] For example, in the plane intersecting the scintillator body of the first electron detector and orthogonal to the electron beam path, the following observation can be made: the light-entry surface of the optical fiber extends completely around the center, and / or the light-entry surface of the optical fiber completely surrounds the scintillator body. If the scintillator body itself completely surrounds the center, there is a region of the plane between the scintillator body and the light-entry surface of the optical fiber in which the locations are arranged where the electrons generated at the object and detected by the second electron detector penetrate the plane. The scintillator body of the first electron detector is thus completely surrounded in this plane by the region where the electrons detected by the second electron detector penetrate the plane.

[0032] Embodiments of the invention are explained in more detail below with reference to the drawings. Fig. Figure 1 is a schematic cross-sectional view of an electron beam microscope according to one embodiment. Fig. Figure 2 is a schematic cross-sectional view of a part of an electron beam microscope according to a second embodiment. Fig. Figure 3 is a schematic cross-sectional view of a part of an electron beam microscope according to a third embodiment. Fig. Figure 4 is a schematic cross-sectional view of a part of an electron beam microscope according to a fourth embodiment. Fig. Figure 5 is a schematic cross-sectional view of a part of an electron beam microscope according to a fifth embodiment. Fig. Figure 6 is a schematic cross-sectional view of a part of an electron beam microscope according to a comparative example. Fig. 7 is a cross-sectional view of a part of the in Fig. 4 electron beam microscope shown along a line VII-VII in Fig. 6. Fig. Figure 8 is a schematic cross-sectional view of part of an electron beam microscope according to another comparative example. Fig. Figure 9 is a schematic cross-sectional view of part of an electron beam microscope according to another comparative example. Fig. Figure 10 is a schematic cross-sectional view of a part of an electron beam microscope according to another comparative example.

[0033] Fig. Figure 1 shows a schematic longitudinal section of an electron beam microscope 1 along a principal axis 3 of the electron beam microscope 1. The electron beam microscope 1 comprises an electron beam source 5 with an electron emitter 7 and an extractor electrode 9. By applying a voltage between the electron emitter 7 and the extractor electrode 9, an electric field is generated at one tip of the electron emitter 7 that is strong enough to extract electrons from the electron emitter 7, accelerate them towards the extractor electrode 9, and partially penetrate an opening 11 in the extractor electrode 9 to generate an electron beam 13 whose beam path lies on the principal axis 3. Fig. Figure 1 shows the electron beam microscope 1 seen from a direction perpendicular to a beam path of the electron beam microscope 1.

[0034] The electrons of the electron beam 13 enter a beam tube 15 at a first end 17 of the beam tube 15 and pass through the beam tube 15 in its longitudinal direction until they exit at a second end 19 of the beam tube 15 to meet an object 21 which is held on a specimen holder 23 of the electron beam microscope 1.

[0035] The electron beam microscope 1 further comprises an objective lens 25 to generate a magnetic field that focuses the electron beam 13 onto a surface of the object 21. For this purpose, the objective lens 25 includes a magnetic yoke 27 with a first pole 29 and a second pole 31, which are rotationally symmetric with respect to the principal axis 3. A magnetic coil 33 is provided within the magnetic yoke 27, through which an electric current flows to generate a magnetic field that emerges from the magnetic yoke 27 at poles 29 and 31 into a gap between the poles 29 and 31. The magnetic field emerging from poles 29 and 31 focuses the electron beam 13 and exhibits a maximum in a plane 33 oriented orthogonally to the principal axis 3.

[0036] The beam tube 15 is an electrode surrounding the electron beam 13 between its first end 17 and second end 19. This electrode is at the same or a higher electrical potential than the extractor electrode 9, allowing the electrons of the electron beam 13 to travel rapidly through the beam tube 15 at high speed. The object 21 and the object holder 23 are at a lower electrical potential compared to the beam tube 15. Therefore, the electrons of the electron beam 13 are decelerated in an electric field between the second end 19 of the beam tube 15 and the surface of the object 21, causing them to strike the object with a desired kinetic energy. This kinetic energy is defined by the potential difference between the electron emitter 7 and the object 21. This potential difference can be, for example, 4 kV to 15 kV.

[0037] The electrons of the electron beam 13 striking object 21 at object location 35 in turn generate electrons that exit object 21 and are accelerated towards the beam tube 15 in the electric field between the second end 19 of the beam tube 15 and the surface of object 21. Some of these electrons enter the beam tube 15 at the second end 19. The electrons entering the beam tube 15 move in the representation of the Fig. 1 upwards and can be detected by a first electron detector 37, a second electron detector 39 and a third electron detector 41.

[0038] The electrons generated at object 21 by the incident electron beam 13 differ in terms of the kinetic energy with which they exit object 21 and in the direction in which they move as they exit object 21. Because of these differences, different electrons exiting object 21 can be detected by the different electron detectors 37, 39, and 41.

[0039] The electrons emitted from object 21 are usually divided into two groups. The electrons of one group are called secondary electrons, and their kinetic energies upon exiting object 21 are less than 50 electron volts. The electrons of the other group are called backscattered electrons, and their kinetic energies are greater than 50 electron volts and less than or equal to the kinetic energy with which the electrons of electron beam 13 strike object 21.

[0040] Due to their lower energy compared to the backscattered electrons, many secondary electrons are deflected more strongly when passing through the electric field between the second end 19 of the beam tube 15 and the surface of the object 21 and can strike a converter 43 of the third electron detector 41. The converter 43 comprises a scintillator body 44 extending around the main axis 3 and having a central opening 45 through which the electrons of the electron beam 13 can pass on their way to the object 21, and through which the electrons generated at the object 21 can pass on their way to detection by the first electron detector 37 and the second electron detector 39. The scintillator body 44 is made of a scintillator material that emits light when electrons strike it. Reference number 47 is in Fig. 1 denotes an exemplary trajectory of an electron generated at object 21 and striking the scintillator body 43. This electron generates light in the scintillator body 43, the exemplary trajectory of which is shown in Fig. 1 is designated with reference numeral 49. The light enters from the scintillator body 43 into an optically coupled light guide 51, which directs the light to a light detector 53. The light detector detects the light and outputs corresponding electrical signals. The light guide 51 has an opening 52 for the passage of electrons, which is aligned with the opening 45 of the scintillator body 44.

[0041] The second electron detector 39 comprises a scintillator body 57 as a converter, which is optically coupled to an optical fiber 59. Reference numeral 61 is used in Fig. 1 denotes an exemplary trajectory of an electron generated by object 21 that strikes the scintillator body 57. Light is generated in the scintillator body 57 by this electron, where reference numeral 63 denotes an exemplary trajectory of such light, which is guided through the optical fiber 59 to a light detector 65, which detects the light and converts it into corresponding electrical signals.

[0042] The electrons striking the scintillator body 57 first pass through a first electrode 67 and then a second electrode 69 before reaching the scintillator body 57. The first electrode 67 and the scintillator body 57 are at the same electrical potential as the beam tube 15. The electrical potential of the second electrode 69 is adjustable and lower than that of the first electrode 67, so that only electrons with sufficiently high kinetic energy and whose direction of flight and trajectory are aligned with respect to the grid can pass through the second electrode 69. By changing the potential of the second electrode 69 and determining the intensity of the light detected by the light detector 65, it is thus possible to select the electrons reaching the scintillator body 57 according to their kinetic energy.The first electrode 67 and the second electrode 69 can be formed from a conductive mesh or grid.

[0043] To shield the electron beam 13 from interference by the electric fields generated between the first electrode 67 and the second electrode 69 and between the second electrode 69 and the scintillator body 57, an electrically conductive tube 71 is provided, which passes through the two electrodes 67 and 69, the converter 57, and the optical fiber 59, centered on the main axis 3. The tube 71 is at the same electrical potential as the beam tube 15.

[0044] To prevent the electrical potential of the tube 71 from influencing the electrical fields between the two electrodes 67 and 69 and between the second electrode 69 and the converter 57, an insulator 73 is provided, which surrounds the tube 71 in the region between the first electrode 67 and the converter 57. Furthermore, another insulator 75 is provided, which surrounds the first electrode 67, the second electrode 69, and the converter 57 externally. However, the insulators 73 and 75 exhibit a certain degree of electrical conductivity, at least on their surfaces facing the annular space between them, so that the electrical potential on the outer surface of the insulators 73 and 75 can change uniformly along their longitudinal direction, and the electrical fields between the electrodes 67 and 69 and between the electrode 69 and the scintillator body 57 are as homogeneous as possible.

[0045] In comparison to the third electron detector 41, the second electron detector 39 detects a greater number of backscattered electrons, as these are deflected less when passing through the objective lens 25. Furthermore, the spectrum of kinetic energies of these electrons can be influenced by changing the electrical potential of the second electrode so that essentially only backscattered electrons are detected.

[0046] Electrons emanating from the object 21 can strike the scintillator body 57 if they are at a distance from the principal axis 3 when passing through the first electrode 67 that is greater than the outer radius of the insulator 73. To also detect electrons that are at a distance from the principal axis 3 in the region of the first electrode 67 that is less than the radius of the insulator 73, the first electron detector 37 is provided. This detector comprises a scintillator assembly 76, which is provided on an end face of the insulator 73 facing the object 21 and includes a scintillator body 77. The scintillator body 77 has the shape of an annular cylinder, wherein a central bore of the scintillator body 77 is penetrated by the tube 71, such that an end 79 of the tube 71 assigning to the object 21 is arranged closer to the object location 35 than a surface of the scintillator body 77 assigning to the object location 35.The outer diameter of the scintillator body 77 is equal to or slightly larger than the outer diameter of the insulator 73.

[0047] Alternatively, the scintillator assembly 76 can also be arranged between the end 79 of the tube 71 that leads to the object 21 and the object location 35. In this case, the inner diameter of the scintillator body 77 can be set smaller than the outer diameter of the tube 71, so that electrons that would otherwise strike the end face of the tube 71 also strike the scintillator assembly 76 of the first electron detector 37 and can be detected.

[0048] Reference number 81 is in Fig. 1 denotes a trajectory of an electron generated at object location 35, which strikes the scintillator arrangement 76. In the scintillator body 77 of the scintillator arrangement 76, this electron generates light, which exits the scintillator arrangement 76 into the vacuum. Reference numeral 83 denotes in Fig. Figure 1 describes an exemplary trajectory of such light. The light strikes a mirror surface 85 of a mirror 87, is reflected by it, and enters an optical fiber 89 of the first electron detector 37 to guide the light to a light detector 91, which detects the light and converts it into electrical signals. The light detector 91 can be arranged outside a vacuum jacket located in the Fig. 1 is not shown and encloses the vacuum space in which the beam path of the electron beam 13 is located. The mirror surface 85 is an optically effective surface that is arranged in the beam path of the light between the scintillator body 77 and the light detector 91.

[0049] The mirror surface 85 has a curved shape. A dashed line 99 indicates this. Fig. 1. An ellipsoid is defined as a mathematical surface created by rotating an ellipse about its major semi-axis. The mirror surface 85 approximates the shape of the ellipsoid 99. For example, the distance between the mirror surface 85 and the ellipsoid 99 at the effective mirror surface 85 is less than 3 mm or less than 1 mm. Advantageously, the ellipsoid 99 is arranged such that the scintillator body 77 is located close to the first focal point of the ellipse generating the ellipsoid 99. A light-entry surface 101 of the optical fiber 89 is then located close to the second focal point of this ellipse. In this way, the largest possible proportion of the light generated by the scintillator body 77 is coupled into the optical fiber 89.The mirror 87 has a recess 103 to allow the electron beam 13 to pass through to the object 21 and to allow the electrons coming from the object 21 to pass through to the converter 57 of the second electron detector 39 and to the scintillator arrangement 76 of the first electron detector. The light-entry surface 101 is at approximately the same electrical potential as the beam tube 15.

[0050] Viewed along the path of the electron beam 13, the objective lens 25 is arranged between the electron beam source 5 and the object location 35. Since the path of the electron beam 13 is in the Fig. In the example shown, if the beam path is straight and extends vertically, this means that the objective lens 25 is positioned higher than the object location 35 and that the electron beam source 5 is positioned higher than the objective lens 25. Furthermore, the scintillator arrangement 76 is arranged along the beam path between the electron beam source 5 and the object location 35, which in the situation of Fig. 1 means that the scintillator arrangement 76 is positioned higher than the object location 35 and that the electron beam source 5 is positioned higher than the scintillator arrangement 76. Furthermore, the mirror surface 85 is positioned along the beam path of the electron beam 13 between the scintillator arrangement 76 and the object location 35, which in the situation of Fig. 1 means that the mirror surface 85 is positioned higher than the object location 35 and that the scintillator arrangement 76 is positioned higher than the mirror surface 85.

[0051] In the illustrated embodiment, the optically effective surface, i.e., the mirror surface 85, is a continuous, contiguous surface. However, it is also possible to design the optically effective surface such that it is composed of several continuous sub-surfaces, with steps provided between adjacent sub-surfaces where the sub-surfaces meet discontinuously. Furthermore, it is possible for the multiple sub-surfaces to be parts of several ellipsoids whose associated ellipses have different semi-axe sizes, with one focal point located near the scintillator body 77 and the other focal point located near the light-entry surface 101.

[0052] Further embodiments and comparative examples of the electron beam microscope are shown below with reference to the figures. Components that, with regard to their structure or function, are similar to those described in the figures are shown below. Fig. The embodiments described in point 1 correspond to those described above, with the same reference numerals, but distinguished by an additional letter. For an understanding of the structure and function of these components, please refer to the entire preceding description.

[0053] Fig. Figure 2 is a schematic cross-sectional view of a part of an electron beam microscope according to a second embodiment. The in Fig. The electron beam microscope shown in 1a differs from the one shown based on the Fig. The electron beam microscope 1 described in section 1 differs only in the design of a first electron detector 37a. The remaining components of the electron beam microscope 1a are the same as described in section 1. Fig. The electron beam microscope shown in Figure 1 is therefore essentially the same and will not be repeated below to avoid repetition. Fig. Furthermore, only the components of the electron beam microscope 1a that are essential for explaining the first electron detector 37a are shown in Figure 2, while the remaining components of the electron beam microscope 1a are shown in Figure 2. Fig. 2 are not shown.

[0054] The electron beam microscope 1a has a first electron detector 37a and a second electron detector 39a. The second electron detector 39a of the electron beam microscope 1a has a structure that corresponds to the structure of the second electron detector 39 of the one described in Fig. The electron beam microscope 1 shown in Figure 1 is identical. The second electron detector 39a comprises a tube 71a centered on a principal axis 3a of the electron beam microscope 1a, through which, during operation, the electron beam generated by a particle beam source passes longitudinally. A first electrode 67a is provided on a side 79a of the tube 71a facing an object under investigation. This electrode is first passed through by an electron coming from the object, whereupon this electron passes through a second electrode 69a and then strikes a scintillator body 57a, which generates light with the electron. Part of this light enters an optical fiber 59a, which guides the light to a light detector 65a. The light detector detects the light and converts it into electrical signals.An insulator 73a surrounding the tube 71a and an insulator 75a surrounding the first electrode 67a, the second electrode 69a and the scintillator 57a with a certain conductivity are provided to shape the electric fields formed between the first electrode 67a and the second electrode 69a and between the second electrode 69a and the scintillator 57a in the inner and outer edge regions.

[0055] A ring-shaped scintillator arrangement 76a of the first electron detector 37a is attached to an end face of the insulator 73a.

[0056] Electrons 81a striking the scintillator body 77a of the scintillator assembly 76a generate light in the scintillator material of the scintillator body 77a. Exemplary trajectories of such light are shown with reference numerals 83a. This light exits the scintillator assembly 76a into the vacuum and from the vacuum into an optical fiber 89a, which guides the light to a light detector 91a. The detector detects the light and generates electrical signals corresponding to the detected light. Some of the light exiting the scintillator body 77a can enter the optical fiber 89a directly, i.e., without reflection from any surfaces. Another portion of the light exiting the scintillator body 77a is deflected at an optically effective surface 85a of an optical element 87a before entering the optical fiber 89a.The optical element 87a is designed to increase the proportion of light generated by the scintillator body 77a and entering the optical fiber 89a. To increase the proportion of light entering the optical fiber 89a and reflected towards the light detector 91a, the optical fiber 89a has a wedge-shaped tapered section 88. An angle γ between the surface of the wedge-shaped tapered section 88 facing the object and the principal axis 3a can, for example, lie in a range between 30° and 70°, and particularly in a range between 40° and 60°.

[0057] Based on the Fig. In the first electron detector 37 of the electron beam system 1, the optically effective surface of the optical element 87 is the mirror surface 85, which has the shape of a part of an ellipsoid 99. Based on the Fig. 2. In the first electron detector 37a, the optical element 87a of the first electron detector 37a is also a mirror, and the optically effective surface 87a is a mirror surface on which the light generated by the scintillator body 77a is reflected and which lies in the beam path of this light between the scintillator body 77a and the optical fiber 89a.

[0058] In contrast to the one based on the Fig. In the electron beam microscope 1, the mirror surface 85a has the shape of a part of a paraboloid. Dashed lines 99a indicate... Fig. 2 A continuation of the paraboloid beyond the mirror surface 85a is shown. The paraboloid 99a is formed by rotating a parabola whose axis of symmetry coincides with the principal axis 3a of the electron beam microscope 1a. The mirror surface 85a approximates the shape of the paraboloid 99a in most of its areas, for example, by a distance between the effective mirror surface 85a and the paraboloid 99a being less than 3 mm or less than 1 mm. The mirror 87a has a recess 103a in a region near the second electron detector 39a to allow electrons generated at the object to pass through to the scintillator body 57a of the second electron detector 39a.

[0059] Fig. Figure 3 is a schematic cross-sectional view of a part of an electron beam microscope 1b according to a third embodiment. The in Fig. The electron beam microscope shown in 1b differs from the one shown based on the Fig. 2. The electron beam microscope 1a described above differs only in the design of a first electron detector 37b. The remaining components of the electron beam microscope 1b are the same as described in 2. Fig. The electron beam microscopes shown in section 2 are essentially the same and will not all be explained again below. Fig. Furthermore, only the components of the electron beam microscope 1b that are essential for explaining the first electron detector 37b are shown in Figure 3, while the remaining components of the electron beam microscope 1b are shown in Figure 3. Fig. 3 are not shown.

[0060] A second electron detector 39b of the electron beam microscope 1b has a structure that is similar to the structure of the second electron detector of the one described in the Fig. 1 and Fig. The second electron detector 39b comprises a tube 71b centered on a principal axis 3b of the electron microscope 1b, which, during operation, is longitudinally penetrated by the electron beam generated by a particle beam source. The second electron detector 39b further comprises a first electrode 67b, a second electrode 69b, a converter configured as a scintillator body 57b, an insulator 73b, and an insulator 75b, as previously described in connection with the second electron detector of the electron microscope shown in the figures. Fig. 1 and Fig. The two electron microscopes shown were explained.

[0061] A ring-shaped scintillator arrangement 76b of the first electron detector 37b is attached to an end face of the insulator 73b.

[0062] Electrons striking a scintillator body 77b of the scintillator assembly 76b generate light in the scintillator material of the scintillator body 77b. An exemplary trajectory of such light is shown with reference numeral 83b. This light exits the scintillator assembly 76b into the vacuum and from the vacuum into an optical fiber 89b, which guides the light 83b to a light detector 91b. The light detector detects the light 83b and generates electrical signals corresponding to the detected light. Some of the light exiting the scintillator assembly 76b can enter the optical fiber 89b directly, i.e., without reflection from any surfaces. Another portion of the light exiting the scintillator assembly 76b is reflected from an optically effective surface 85b of an optical element 87b before entering the optical fiber 89b.The optical element 87b is designed to increase the proportion of light generated by the scintillator body 77a and entering the light guide 89b. Based on the... Fig. In the first electron detector 37a of the electron beam microscope 1a, the optically effective surface 85a of the optical element 87a is a mirror surface having the shape of a part of a paraboloid 99a. This is also the case for the first electron detector 37b. Dashed lines 99b are shown in Fig. 3 shows a continuation of the paraboloid beyond the mirror surface 85b. The paraboloid 99b is created by rotating a parabola. However, an axis of symmetry 111 of the paraboloid 99b does not lie on the principal axis 3b of the electron beam microscope 1b, as is the case with the first electron detector 37a of the electron beam microscope 1a of the Fig. 2 was the case. Rather, the axis of symmetry 111 of the paraboloid extends at an angle α to the principal axis 3b of the electron beam microscope 1b. The angle α is the smaller of the two angles between the axis of symmetry 111 and the principal axis 3b, is greater than 10° and is, for example, 20°.

[0063] A third electron detector 41b of the electron beam microscope 1b comprises a scintillator body 44b, a light guide 51b and a light detector 53b, as already described in connection with the third electron detector 41 of the electron beam microscope of the Fig. 1 was described. The scintillator body 44b and the light guide 51b have aligned openings 45b and 52b respectively, through which the electrons of the electron beam can pass on their way to the object and the electrons generated at the object can pass on their way to detection by the first electron detector 37b and the second electron detector 39b.

[0064] The optical fiber 89a of the first electron detector 37a also has a corresponding opening. In contrast, the optical fiber 89b of the first electron detector 37b does not require such an opening, since all the light reflected from the mirror surface 85b is directed to one side of the principal axis 3b at such a large distance from the principal axis 3b before entering the optical fiber 89b that such an opening is unnecessary.

[0065] However, the mirror 87b itself has a recess 103b in an area near the principal axis 3b to allow the passage of electrons generated at the object to the scintillator body 57b of the second electron detector 39b.

[0066] Fig. Figure 4 is a schematic cross-sectional view of a part of an electron beam microscope according to a fourth embodiment. The in Fig. The electron beam microscope shown in 1c differs from those shown based on the Fig. The electron beam microscopes described in sections 1 to 3 differ only in the design of a first electron detector 37c. The remaining components of the electron beam microscope 1c are those described in the Fig. The electron beam microscopes shown in 1 to 3 are essentially the same and will not be explained again below. Fig. Figure 4 shows only the components of the electron beam microscope 1c that are essential for explaining the first electron detector 37c, while the remaining components of the electron beam microscope 1c are shown in Fig. 4 are not shown.

[0067] A second electron detector 39c of the electron beam microscope 1c has a structure that is similar to the structure of the second electron detector of the one described in the Fig. The second electron detector 39c is identical to the electron beam microscopes shown in Figures 1 to 3. It also comprises a tube 71c centered on a principal axis 3c of the electron beam microscope 1c, which, during operation, is longitudinally penetrated by the electron beam generated by a particle beam source. The second electron detector 39c further comprises a first electrode 67c, a second electrode 69c, a scintillator body 57c, an insulator 73c, an insulator 75c, an optical fiber 59c, and a light detector 65c, as previously described in connection with the second electron detector of the electron beam microscope shown in Figures 1 to 3. Fig. The electron microscopes shown in sections 1 to 3 were explained.

[0068] A ring-cylindrical scintillator arrangement 76c of the first electron detector 37c is attached to an end face of the insulator 73c.

[0069] Electrons striking the scintillator arrangement 76c generate light in a scintillator material of a scintillator body 77c of the scintillator arrangement 76c. Reference numerals 83c are used in Fig. Figure 4 shows two exemplary trajectories of such light. This light exits the scintillator assembly 76c into the vacuum and from the vacuum into an optical fiber 89c, which guides the light to a light detector 91c. The detector detects the light and outputs electrical signals corresponding to the detected light. A portion of the light exiting the scintillator assembly 76c is deflected at an optically effective surface 85c of an optical element 87c before entering the optical fiber 89c. The optical element 87c is designed to increase the proportion of light generated by the scintillator body 77c that enters the optical fiber 89c. The optical element 87c is a lens having two optically effective surfaces 85c at which the light is refracted and thus deflected in its direction. The lens 87c has an optical axis 113 which extends at an angle α to the principal axis 3c of the electron beam microscope 1c.The angle α can be, for example, 10°. Due to the optical axis 113 of the lens 87c extending obliquely to the principal axis 3c, it is similar to the electron beam microscope 1b. Fig. 3. It is possible that the optical fiber 89c of the first electron detector 37c does not have to have an opening in the optical fiber 89c.

[0070] In contrast, a light guide 51c of a third electron detector 41c has such an opening 52c. The lens 87c also provides an opening 103c to allow the electrons to pass through the optical element.

[0071] In the illustrated embodiment, the lens 87c has two optically effective surfaces 85c, each formed by a continuous, contiguous area. However, it is also possible to design one or both optically effective surfaces as being composed of several continuous sub-areas, with steps provided between adjacent sub-areas where the sub-areas meet discontinuously. The multiple sub-areas can be arranged on a common lens body or on separate lens bodies, similar to a Fresnel lens.

[0072] In the figures of the embodiments described above, the tube 71 and other components of the electron beam microscope are, of course, shown schematically. In particular, due to the limitations of the representation, the geometric dimensions and proportions of the components shown do not correspond to the actual embodiments. For example, the inner diameter of the tube 71 may be 1.0 mm to 1.5 mm, the inner diameter of the openings 45 and 52 may be 3 mm to 4 mm, and the inner diameter of the second end 19 of the beam tube 15 may be 4 mm to 5 mm.

[0073] Fig. Figure 5 is a schematic cross-sectional view of a part of an electron beam microscope 1d according to a fifth embodiment. The in Fig. The electron beam microscope shown in image 5 (1d) differs from the one shown based on the Fig. The electron beam microscope 1 described in Figure 1 is modified by the fact that a semiconductor detector 57d is provided as a converter for a second electron detector 39d. This semiconductor detector generates electrical detection signals from incident electrons 61d, which are output via an electrical line 62 to a control unit of the electron beam microscope 1d (not shown in the figures). The electrons 61d striking the semiconductor detector 57d, which were generated at the object by the incident electron beam 13d, first pass through a first electrode 67d, formed by a plurality of metal grid bars 68, and then through a second electrode 69d, formed by a plurality of metal grid bars 70. The first electrode 67d is provided on a projection 72 of a tube 71d, which is penetrated longitudinally by the electron beam 13d.Thus, the first electrode 67d is at the electrical potential of the tube 71d, whose electrical potential in turn is that of one in . Fig. The beam tube 15 of the electron beam microscope 1d (not shown) is located at this electrical potential. The semiconductor detector 57d is also at this electrical potential. The electrical potential of the second electrode 69d is variable to vary the kinetic energy of the electrons 61d, which they must possess at a minimum to reach the semiconductor detector 57d.

[0074] A scintillator arrangement 76d of a first electron detector 37d is provided in front of an end face of an insulator 73d facing the object, or of the projection 72 of the tube 71d, and surrounds the tube 71d as an annular cylinder. The scintillator arrangement 76d comprises a scintillator body 77d having an electron receiving surface 82 onto which electrons 81d coming from the object strike. The scintillator body 77d generates light with the incident electrons 81d, with an exemplary light beam in Fig. 5 is designated with the reference numeral 83d. This light beam 83d passes through the scintillator body 77d and enters a light-guiding body 78, which is optically coupled to the scintillator body 77d. After two internal reflections at surfaces of the light-guiding body 78, the light beam 83d passes through the scintillator body 77d again and exits the scintillator body 77d, and thus the scintillator assembly 76d, into the vacuum, in order to pass through a Fig. 5 not shown light detector of the first electron detector 37d to be detected.

[0075] The surfaces of the ring cylinder formed from the scintillator body 77d and the light-guiding body 78 are provided with two different types of coatings. A first coating 80 is applied to a bottom surface of the ring cylinder in a radially outer region and in an axially lower region of its outer surface. This coating 80 is transparent and electrically conductive. A second coating 80' is applied to the bottom surface in its radially inner region, the entire inner surface, the entire top surface, and to the upper surface of the outer surface. This coating 80' is light-reflecting and electrically conductive. Thus, the entire ring cylinder consisting of the scintillator body 77d and the light-guiding body 78 is provided with the electrically conductive coatings 80 and 80' to prevent local electrical charges on the surface caused by any incident electrons.The coating 80 is transparent to allow light to pass through to the light detector. The area of ​​the surface of the scintillator assembly 76d coated with the coating 80 forms a light-emitting surface 100 of the scintillator assembly 76d. The coating 80' is light-reflecting to direct as much light as possible to the area of ​​the surface of the ring cylinder coated with the transparent coating 80.

[0076] At the in Fig. In the embodiment described in Figure 5, the scintillator body 77d is joined with the light-guiding body 78 to form a ring cylinder. However, it is also possible to form the entire ring cylinder from only one scintillator body, without an additional light-guiding body. Furthermore, the scintillator body 77d can be very thin and, for example, applied as a layer to the light-guiding body 78.

[0077] To detect the light 83d generated by the scintillator body 77d through incident electrons 81d, various configurations of light detectors and, if necessary, optical elements can be provided. For example, the following can be used based on the Fig. 1, Fig. 2, Fig. 3 and Fig. The four combinations described can be used as light detectors and optical elements for detecting light 83d. Furthermore, the following can be used based on the Fig. 5 explained scintillator arrangement 76d also as the scintillator arrangement of the first electron detector of the based on the Fig. The electron microscopes described in sections 1 to 4 can be used.

[0078] An electron beam microscope 1e, according to a comparative example, is described below using the following: Fig. 6 and Fig. 7 explained. Fig. 6 a schematic cross-sectional view of part of the electron beam microscope 1e, and Fig. Figure 7 is a cross-sectional view along line VII-VII in Fig. 6 of part of the electron beam microscope 1e.

[0079] The electron beam microscope 1e also comprises a first electron detector 37e and a second electron detector 39e. The second electron detector 39e, in turn, comprises a first electrode 67e and a second electrode 69e, through which an electron 61e generated at an object must pass in order to strike a converter 57e of the second electron detector 39e. The converter generates a signal, such as a light signal or an electrical signal, upon contact with the striking electron 61e. To shape the electric boundary fields between the first electrode 67e and the second electrode 69e, and between the second electrode 69e and the converter 57e, an insulator 73e is provided, which surrounds a tube 71e through which an electron beam 13e passes longitudinally.

[0080] Even when configured according to Fig. 6. The second electron detector 39e has a dead zone in front of the end face of the insulator 73e facing the object and in front of the end face of the tube 71e facing the object. Electrons generated on the object during operation of the electron microscope strike this dead zone without being detected. To detect such electrons, a scintillator assembly 76e is arranged at an end 79e of the tube 71e facing the object. This scintillator assembly converts electrons 81e coming from the object into light, which can be detected by a light detector 91e of the first electron detector 37e. The scintillator assembly 76e has the shape of an annular cylinder, composed of a scintillator body 77e and a light-guiding body 78e, and provided with coatings 80e and 80'e. The coating 80e is electrically conductive and transparent, while the coating 80'e is electrically conductive and reflective.

[0081] Level VII-VII in Fig. 6 extends orthogonally to a principal axis 3e of the electron beam microscope 1e and penetrates the scintillator body 77e. In the cross-sectional view of the Fig. Figure 7 shows that the electron beam 13e penetrates the plane VII-VII at a center of the scintillator arrangement 76e, which coincides with the principal axis 3e. The scintillator body 77e at least partially surrounds the center 3e, and in the comparative example of the Fig. 6 and Fig. 7 completely, since the scintillator body forms a complete ring around the principal axis 3e. However, it is also possible that the scintillator body only partially surrounds the principal axis 3e, or that several scintillator bodies are provided, each of which only partially surrounds the principal axis 3e as segments.

[0082] Furthermore, in plane VII-VII, the scintillator body 77e is arranged between the center 3e and a region of plane VII-VII that is penetrated by the electrons detected by the second electron detector 39e. A point marked with reference numeral 61e in Fig. 7 represents an electron detected by the second electron detector 39e, which penetrates the VII-VII plane outside the scintillator body 77e.

[0083] The description of the conditions at level VII-VII given so far, based on the Fig. 7 are also in the embodiments of the Fig. 1, Fig. 2, Fig. 3, Fig. 4 and Fig. 5 is fulfilled, because there too a scintillator body is formed as a ring that at least partially surrounds the main axis of the electron microscope or the center, and it is arranged between the center and the area of ​​the plane that is penetrated by the electrons generated on the object, which are detected by the second electron detector.

[0084] While the embodiments described above incorporate an optical element, such as a mirror, in the embodiments of Fig. 1, Fig. 2 and Fig. 3 or a lens in the embodiment of Fig. 4, to use in order to increase the proportion of light generated by the scintillator body that reaches the light detector of the first electron detector, is in the comparative example of the Fig. 6 and Fig. 7 no such optical element is provided, and the light 83e exiting the scintillator arrangement 76e into the vacuum enters directly into an optical fiber 89e of the first electron detector 37e. For this purpose, the scintillator arrangement 76e has a light-exit surface 100e through which the light 83e exits the scintillator arrangement 76e, and the optical fiber 89e has a light-entry surface 101e through which the light 83e enters the optical fiber 89e. The optical fiber 89e serves to guide the light 83e entering it to the light detector 91e. Fig. Figure 6 shows a vacuum jacket 121 which is penetrated by the light guide 89e, so that the light detector 91e can be arranged outside a vacuum space of the electron beam microscope 1e.

[0085] Among the surfaces of the scintillator arrangement 76e, a portion assigning to the light entry surface 101e of the light guide 89e is designed as the light exit surface 100e, in that the surface of the scintillator arrangement 76e is provided there with the electrically conductive and translucent coating 80e. All other surfaces of the scintillator arrangement 76e are provided with the electrically conductive and light-reflecting coating 80'e. With reference numeral 123 in Fig. The seven marked points represent locations where light is generated in the scintillator body 77e, and the lines 83e extending from the points 123 exemplify light that is reflected from surfaces coated with the reflective coating 80'e and exits the scintillator assembly 76e at the light-emitting surface 100e coated with the translucent coating 80e to enter the optical fiber 89e. The light-entry surface 101e of the optical fiber 89e is positioned at a distance from the light-emission surface 100e of the scintillator assembly, so that electrons 61e, generated at the object and detected by the second electron detector 39e, can also penetrate plane VII-VII in the area between the light-entry surface 101e of the optical fiber 89e and the light-emission surface 100 of the scintillator assembly 76e.

[0086] In the sectional view of the Fig. Figure 7 also shows that the light entry surface 101e is concave in order to reduce the proportion of light reflected at the light entry surface 101e and to refract the light entering the optical fiber 89e towards the light detector.

[0087] From the sectional view of the Fig. Figure 6, in the plane containing the principal axis 3e or the electron beam 13e, further shows that the light-emitting surface 100e of the scintillator arrangement 76e extends essentially parallel to the principal axis 3e and the electron-receiving surface of the scintillator body 76e extends essentially orthogonally to the principal axis 3e. Furthermore, in the sectional view of the Fig. 6. The light entry surface 101e of the optical fiber 89e is also essentially parallel to the principal axis 3e. However, it is also possible to design the light entry surface 101e so that it is not straight but concave in order to reduce the proportion of light reflected at the light entry surface 101e and to refract the incoming light towards the light detector 91e.

[0088] The optical fiber 89e advantageously has a larger extent in the direction of the principal axis 3e than the light-emitting surface 100e, thereby increasing the proportion of light exiting the scintillator arrangement 76e and entering the optical fiber 89e. The optical fiber 89e extends partially near the second electrode 67e of the second electron detector 39e, with the second electrode 67e defining the position of the optical fiber 89e in the illustration of the Fig. 6 upwards limited. In order to position the light emission surface 100e of the scintillator arrangement 76e approximately centrally opposite the light emission surface 101e of the optical fiber 89e, a spacer 125 is provided between the first electrode 67e of the second electron detector 39e and the scintillator arrangement 76e of the first electron detector 37e, which surrounds the tube 71e similarly to the insulator 73e. Due to the spacer 125, the scintillator arrangement 76e is positioned at a greater distance from the first electrode 67e of the second electron detector 39e than in the diagrams based on the Fig. 1 to 5. Based on the Fig. In embodiments 1 to 5 described, the tube 71 passes through the scintillator arrangement 76 or the scintillator arrangement 76 surrounds the lower end 79 of the tube 71.

[0089] In the comparative example of the Fig. 6 and Fig. 7 is an inner diameter of the ring-cylindrical scintillator arrangement 76e slightly smaller than an inner diameter of the tube 71e, so that electrons can also strike and be detected on the electron receiving surface 82e of the scintillator arrangement 76e which in the embodiments of the Fig. 1 to 5 would hit the end face of pipe 71 that is assigned to the object.

[0090] In the sectional view of the Fig. Figure 6 shows that the cross-sectional shape of the ring-cylindrical scintillator arrangement 76e is not rectangular but pentagonal such that an obliquely extending surface is provided on the top and inside of the ring-cylindrical shape, the surface normal of which extends at approximately 45° to a surface normal of the electron receiving surface 82e. This is shown in the sectional view of the Fig. The 6 obliquely and conically extending surface on the ring-cylindrical shape of the scintillator arrangement 76e serves to increase the proportion of light reflected to the light guide 89e from the light generated in the scintillator body 77e.

[0091] Fig. Figure 8 is a schematic cross-sectional view of a part of an electron beam microscope according to another comparative example. The electron beam microscope 1f of the Fig. 8 differs from the one based on the Fig. 6 and Fig. 7 explained electron beam microscope 1e by the fact that light 83f emerging from a scintillator arrangement 76f of a first electron detector 37f is not guided by a light guide (89e in Fig. 6) is directed to a light detector 91f of the first electron detector 37f, but that a lens 127 with positive refractive power is provided in a beam path of the light 83f between the scintillator arrangement 76f and the light detector 91f in order to increase the proportion of the light reaching the light detector 91f.

[0092] Otherwise, the electron beam microscope 1f also has a first electron detector 37f and a second electron detector 39f. The second electron detector 39f is configured to select the kinetic energy of the electrons generated at the object and subsequently detected, for which purpose these electrons pass through a first electrode 67f and a Fig. 8. A second electrode (not shown), to which a variable electrical potential can be applied, passes through. The scintillator arrangement 76f of the first electron detector 37f is arranged in front of an insulator 73f and a tube 71f of the second electron detector 39f through which the electron beam 13f passes. This scintillator arrangement 76f is also annular-cylindrical in shape, the surfaces of which are coated with coatings 80f and 80'f. The coatings 80f and 80'f are designed similarly to those of the scintillator arrangement of the first electron detector 37f, which is shown in the diagram. Fig. 6 and Fig. 7. Scintillator arrangement described, in which a light-emitting surface 100f is formed on one side of the scintillator arrangement 76f facing the lens 127. This light-emitting surface is provided with the electrically conductive and transparent coating 80f, while all other parts of the surface of the scintillator arrangement 76f are provided with the electrically conductive and light-reflecting coating 80'f. The light 83f emerging divergently from the light-emitting surface 100f of the scintillator arrangement 76f is collimated by the lens 127 and directed onto the light detector 91f.

[0093] In the first electron detector 37f of the comparative example, the lens 127 is used to increase the proportion of light 83f emerging from the scintillator arrangement 76f that reaches the light detector 91f. In the example based on the Fig. In the embodiment described in section 4, lens 87c is also used for this purpose. However, in the embodiment of Fig. 4. The electron receiving surface of the scintillator arrangement is used as the light emission surface, so that the light 83b exiting the scintillator arrangement is directed essentially downwards, towards the object, which is why the lens 87c is also arranged along the beam path of the electron beam 13c between the scintillator arrangement 76c and the object. In the comparative example of the Fig. In contrast, the electron receiving surface 82f of the scintillator arrangement 76f is provided with the light-reflecting coating 80'e, and only a portion of the side surface of the scintillator arrangement 76f is used as the light emission surface 100f, so that the light 83f is emitted divergently from the scintillator arrangement 76f essentially perpendicular to the principal axis 3f. To enable the arrangement of the lens 127, which is larger than the scintillator arrangement 76f, near the first electrode 67f, a spacer 125f is arranged between the first electrode 67f and the scintillator arrangement 76f.

[0094] Fig. Figure 9 is a schematic cross-sectional view of a part of an electron beam microscope 1h, according to another comparative example. The electron beam microscope 1h has a similar structure to the one shown in the Fig. 6 and Fig. 7 explained electron beam microscope 1e. It differs from this essentially in the design of a light entrance surface 101h of a light guide 89h of a first electron detector 37h and the design of a light exit surface 100h of a scintillator arrangement 76h of the first electron detector 37h. While the light entrance surface 101e of the light guide 89e of the first electron detector 37e of the electron beam microscope 1e of the Fig. 6 and Fig. 7 the scintillator arrangement 76e only on one side (the right side in the Fig. 6 and Fig. 7) The light entry surface 101h of the optical fiber 89h partially surrounds the scintillator arrangement 76h, as seen in a plane VIIh orthogonal to the beam path of an electron beam 13h, which intersects a scintillator body 77h of the scintillator arrangement 76h. The electron receiving surface 82h, projected onto the plane VIIh, has the shape of a circular ring centered on the principal axis 3h. In addition, the optical fiber 89h has a wedge-shaped tapered region 88h to accommodate light entering the optical fiber 89h via the light entry surface 101h, as can be seen from the Fig. 2 already explained, to orient by reflection towards an end of the optical fiber 89h opposite region 88h, where a light detector of the first electron detector 37h (in Fig. 9 (not shown) is arranged.

[0095] Of the various surfaces of the scintillator assembly 76h, the entire outer surface of the ring-cylindrical body is provided with an electrically conductive, translucent coating 80h to form the light-emitting surface 100h. All other surfaces of the scintillator assembly 76h are provided with an electrically conductive and light-reflecting coating 80'h.

[0096] Fig. Figure 10 is a schematic cross-sectional view of a part of an electron beam microscope 1i, which has a similar structure to the preceding one based on the Fig. Figures 1 to 9 described electron beam microscopes, which have a first electron detector 37i and a second electron detector 39i. The second electron detector 39i is configured to select the kinetic energy of the electrons generated at the object and subsequently detected, for which purpose these electrons pass through a first electrode 67i and a Fig. 10. A second electrode (not shown) to which a variable electrical potential can be applied.

[0097] Unlike the previous ones, based on the Fig. In the electron beam microscopes described in Figures 1 to 9, the first electron detector 37i does not include a scintillator body as a converter for converting electrons 81i emanating from the object into light. Instead, the first electron detector 37i includes a semiconductor detector 77i as a converter for generating electrical signals as a result of a detection event triggered in the semiconductor detector 77i by the impact of an electron 81i. The generated electrical signals are derived from the semiconductor detector 77i via an electrical conductor 133 and fed to a control unit of the electron microscope 1i, which is not shown in the figure.

[0098] From the object's point of view, the semiconductor detector 77i is arranged in front of an annular end face of an insulator 73i of the second electron detector 39i in order to detect the electrons 81i which would not be detectable without the presence of the semiconductor detector 77i.

[0099] Between the semiconductor detector 77i and the first electrode 67i of the second electron detector 39i, a ring-shaped spacer 175i is arranged, which can also be omitted, so that the semiconductor detector 77i is arranged closer to the first electrode 67i.

Claims

[1] Electron beam microscope, comprising: an electron beam source (5) configured to produce an electron beam (13); an object holder (23) configured to hold an object (21) at an object location (35) upon which the electron beam (13) strikes; an objective lens (25) is arranged along a beam path of the electron beam (13) between the electron beam source (5) and the object location (35) and is configured to focus the electron beam (13) at the object location (35); and a first electron detector (37) configured to detect electrons (81) generated by the electron beam (13) at the object (21); the first electron detector (37) comprises: a scintillator arrangement (76d) which is arranged along the beam path of the electron beam between the electron beam source (5) and the object location (35) such that the electrons (81d) generated at the object (21) strike a scintillator body (77d) of the scintillator arrangement (76d), wherein the scintillator body (77d) is formed from a scintillator material which generates light (83d) with incident electrons (81d), a light detector (91) configured to detect light (83d) generated by the scintillator body (77d) and convert it into electrical signals, and an optical element (87) having an optically effective surface (85) arranged along the beam path of the electron beam between the scintillator arrangement (76) and the object location (35) and arranged in a beam path of the light (83) detected by the light detector (91) between the scintillator body (77) and the light detector (91); characterized by , that the scintillator arrangement (76d) has an electron receiving surface (82) onto which the electrons generated at the object (21) meet the scintillator body (77d); wherein the scintillator arrangement (76d) has a light-emitting surface (100) through which the light (83d) generated by the scintillator material exits the scintillator arrangement (76d); and wherein the electron receiving area (82) and the light emission area (100) overlap at least partially. [2] Electron beam microscope according to claim 1, wherein the optical element is a mirror (87) and the optically effective surface is a mirror surface (85) on which the light (83) detected by the light detector (91) is reflected. [3] Electron beam microscope according to claim 2, wherein the mirror surface (85) is a curved surface. [4] Electron beam microscope according to claim 3, wherein an ellipsoid (99) adapted to the mirror surface (85) exists such that a maximum distance between the mirror surface (85) and the ellipsoid (99) is less than 3 mm. [5] Electron beam microscope according to claim 4, wherein a distance between a focal point of the ellipsoid (99) and the scintillator body (77) is less than 5 mm or less than 3 mm. [6] Electron beam microscope according to claim 3, wherein a paraboloid (99a) adapted to the mirror surface (85a) exists such that a maximum distance between the mirror surface (85a) and the paraboloid (99a) is less than 3 mm. [7] Electron beam microscope according to claim 1, wherein the optical element is a lens (87c) and the optically effective surface is a lens surface (85c) of the lens (87c) at which the light (83c) detected by the light detector (91c) undergoes refraction. [8] Electron beam microscope according to claim 7, wherein the lens surface (85c) is formed by an electrically conductive layer that is transparent to the light (83c) generated by the scintillator body. [9] Electron beam microscope according to claim 7 or 8, wherein the lens has an optical axis (113) which encloses a smallest angle (α) with the beam path of the electron beam (13c) which is greater than 4° and which is particularly greater than 10°. [10] Electron beam microscope according to any one of claims 1 to 9, wherein the optically effective area (85) is greater than 10 mm 2 , especially larger than 100 mm 2 is. [11] Electron beam microscope according to one of claims 1 to 10, wherein the optical element (87) has a recess (103) through which the beam path of the electron beam (13) extends. [12] Electron beam microscope according to one of claims 1 to 11, wherein the first electron detector (37) comprises a light guide (89) which is arranged in the beam path of the light (83) detected by the light detector (91) between the optically effective surface (85) and the light detector (91). [13] Electron beam microscope according to any one of claims 1 to 12, further comprising a second electron detector (39) comprising a converter (57), a first electrode (67), a second electrode (69), a tube (71) and an insulator (73); wherein the beam path of the electron beam (13) passes through the tube (71) in its longitudinal direction; wherein the converter (57), the first electrode (67) and the second electrode (69) are each arranged outside the tube (71) and along the path of the electron beam at a distance from each other; wherein the converter (57) is arranged along the beam path of the electron beam between the electron beam source (5) and the first electrode (67) such that electrons (61) generated at the object (21) pass through the first electrode (67) and hit the converter (57); wherein the converter (57) is configured to convert the electrons (61) generated at the object (21) into electrical or optical signals (63); wherein the second electrode (67) is arranged along the beam path of the electron beam, between the first electrode (69) and the converter (57) and the electrons (61) generated at the object (21) pass through the second electrode (69) after passing through the first electrode (67); wherein the tube (71) has an electrically conductive inner sheath; wherein the insulator (73) is made of an electrically insulating material; wherein the insulator (73) surrounds the tube (71) along the path of the electron beam at least in a region between the first electrode (67) and the second electrode (69) and in a region between the second electrode (69) and the converter (57); and wherein the scintillator body (77) of the first electron detector (37) is arranged along the beam path of the electron beam, between the first electrode (67) and the object location (35) or between the second electrode (69) and the object location (35) and, viewed in the direction of the beam path, overlaps at least partially with the insulator (73). [14] Electron beam microscope according to claim 13, wherein the scintillator arrangement (76d) of the first electron detector (37d) is supported on the tube (71d). [15] Electron beam microscope according to any one of claims 1 to 14, further comprising a beam tube (15) having an electrically conductive inner lining into which the electron beam (13) enters at a first end (17) of the beam tube (15) and from which the electron beam exits at a second end (19) of the beam tube (15); wherein the converter (76) of the first electron detector (37) is arranged along the beam path of the electron beam between the first end (17) and the second end (19) of the beam tube (15) and inside the beam tube (15). [16] Electron beam microscope according to claim 15, wherein the first end (17) of the beam tube (15) is arranged along the beam path of the electron beam between the electron beam source (5) and the converter (76) of the first electron detector (37); and / or wherein the first end (17) of the beam tube (15) is arranged along the beam path of the electron beam between the electron beam source (5) and the converter (57) of the second electron detector (39). [17] Electron beam microscope according to claim 15 or 16, wherein the second end (19) of the beam tube (15) is arranged along the beam path of the electron beam (13), between the converter (76) of the first electron detector (37) and the object location (35); and / or wherein the second end (19) of the beam tube (15) is arranged along the beam path of the electron beam (13) between the converter (57) of the second electron detector (39) and the object location (35). [18] Electron beam microscope according to any one of claims 15 to 17, wherein the objective lens (25) provides a focusing magnetic field for focusing the electron beam (13), which has a maximum (33) along the beam path; wherein the maximum (33) is arranged along the beam path between the first end (17) and the second end (19) of the beam tube. [19] Electron beam microscope according to any one of claims 15 to 18, wherein the objective lens (25) provides a focusing magnetic field for focusing the electron beam (13), which has a maximum along the beam path; wherein the converter (76) of the first electron detector is arranged along the beam path between the electron beam source and the maximum.

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