Electron beam microscope

Abstract

An electron beam microscope comprises an electron beam source 3, a specimen holder 25, an objective lens 27, a beam tube 17, and an electron detector 42. The electron detector 42 comprises a reflector plate 43 arranged between the first end 19 of the beam tube 17 and the second end 21 of the beam tube 17 within the beam tube 17 such that the electrons 41 generated on the specimen 23 impinge on and are reflected by the reflector plate 43. The electron detector 42 further comprises a converter 48 arranged between the reflector plate 43 and the specimen 23 and configured to convert the electrons 47 reflected by the reflector plate 43 into electrical or optical signals.

Description

The invention relates to an electron beam microscope comprising an electron detector having a converter arranged within a beam tube which generates signals detectable from electrons, such as photons or electrical signals.A conventional electron beam microscope comprises an electron beam source for generating an electron beam, an object holder for holding an object to be examined with the electron beam microscope, an objective lens for focusing the electron beam on the object, and an electron detector for detecting electrons generated by the electron beam on the object. The electron beam microscope further comprises a steel tube having an electrically conductive inner jacket which is arranged between the electron beam source and the object and through which the electron beam passes. The beam tube is at a high electrical potential compared to the electron beam source and the object, so that the electrons are accelerated into the beam tube, pass through it at a high speed and thus rapidly before they are decelerated after exiting from the beam tube toward the object and strike the object with a desired kinetic energy. A portion of the electrons generated by the electron beam on the object is accelerated into the beam pipe and can be detected by the electron detector. The electron detector comprises a scintillator arranged inside the beam tube, which generates light with impinging electrons to be detected, a light guide which transports a part of the generated light to the outside of the beam tube, and a light detector which detects this light and converts it into electrical signals which can be processed.The publications US 2006 / 0 226 360 A1, U.S. Pat. No. 5,872,358 A and DE 198 28 476 A1 show some known solutions for arranging detectors, scintillators and light guides in electron beam microscopes.The arrangement of the scintillator and the light guide is subject to design boundary conditions and is therefore not freely selectable. The location and the size of the surface of the scintillator, on which the electrons to be detected must strike, are thus also limited by these boundary conditions.It is desirable to obtain more flexible boundary conditions for the location and size of the area on which electrons to be detected must strike during the construction of the electron beam microscope.To achieve this object, an electron beam microscope is proposed, which includes an electron beam source, an object holder, an objective lens, a beam tube, and an electron detector. The electron beam source is configured to generate an electron beam that strikes an object supported on the object holder at an object location. The objective lens is arranged between the electron beam source and the object when viewed perpendicular to a beam path of the electron beam, and is configured to focus the electron beam at the object location. The beam tube has an electrically conductive inner jacket and has a first end at which the electron beam enters the beam tube and a second end at which the electron beam exits the beam tube. The electron detector comprises a reflector plate which, viewed perpendicularly to a beam path of the electron beam, is arranged between the first end of the beam tube and the second end of the beam tube within the beam tube in such a way that electrons generated at the object by the incident electron beam strike the reflector plate. A portion of the electrons striking the reflector plate is reflected or backscattered by the latter as backscattered electrons ("backscattered electrons") and strikes a converter of the electron detector which, as seen perpendicular to a beam path of the electron beam, is arranged between the reflector plate and the object location. The electrons striking the converter are converted by the converter into electrical or optical signals.According to exemplary embodiments, the converter is formed by a semiconductor detector which generates electrical signals by the electrons reflected by the reflector plate and impinging on the semiconductor detector, which electrical signals can be evaluated. These electrical signals represent the intensity of the electrons striking the semiconductor detector, which are electrons reflected from the reflector plate. The intensity thereof in turn represents an intensity of the electrons which are generated by the electron beam at the point of incidence, enter the beam tube and strike the reflector plate. Thus, the electrical signals generated by the semiconductor detector also represent the intensity of the electrons generated by the electron beam at the point of incidence and striking the reflector plate. The intensity of these electrons in turn depends, inter alia, on the properties of the material of the object at the point of incidence, so that conclusions can be drawn about the properties of the material at the point of incidence by evaluating the electrical signals. According to other exemplary embodiments, the converter comprises a scintillator material configured to generate light by the electrons reflected from the reflector plate and incident on the scintillator material. The electron detector here furthermore comprises a light detector which detects at least part of the light generated by the scintillator material and generates corresponding electrical signals. These signals also represent the intensity of the electrons generated by the electron beam at the location of incidence, which electrons strike the reflector plate.In the conventional electron beam microscope, the electron detector is constituted by a converter such as a converter made of a scintillator material or a semiconductor detector, and the electrons generated at the object location from the electron beam and entering the beam tube directly strike the converter. In this case, the converter on which the electrons to be detected strike can only be installed at locations in the electron beam microscope where it is possible to provide the installation space for a semiconductor detector or a scintillator with an associated light detector and optionally light guides. In the electron beam microscope according to the embodiments described here, only the reflector plate, which can take up a comparatively small installation space, has to be arranged at the location where the detection of desired incident electrons is desired. These may be locations where the arrangement of a converter of the conventional electron beam microscope is not possible. Thus, the possibilities for detecting electrons generated by the electron beam on the object are expanded in comparison with the conventional electron beam microscope.According to exemplary embodiments, the converter, as seen perpendicular to the beam path of the electron beam, is arranged between the reflector plate and the second end of the beam tube within the beam tube.According to further exemplary embodiments, the objective lens provides a focusing electric field or a focusing magnetic field for focusing the electron beam. The focusing magnetic field has a maximum when viewed perpendicularly to the beam path of the electron beam. According to exemplary embodiments, the reflector plate is arranged between the first end of the beam tube and the maximum of the focusing magnetic field. According to further exemplary embodiments herein, the converter is arranged between the reflector plate and the maximum of the focusing magnetic field.According to exemplary embodiments, the reflector plate is designed such that it reflects the impinging electrons as well as possible. For this purpose, the surface of the reflector plate can be made of a material which comprises atoms with a high atomic number. For example, a proportion of atoms on the surface of the reflector plate of more than 50 percent by weight has the atomic number greater than 45.The electron beam microscope can furthermore comprise a potential supply system which supplies a first electrical potential U1 to the electron beam source, a second electrical potential U2 to the object holder, a third electrical potential U3 to the reflector plate, a fourth electrical potential U4 to the converter and a fifth electrical potential U5 to the beam tube.According to example embodiments, U 5-U 2>500 volts. In particular, it can be true that the potential difference U5-U2is greater than 1,000 V, greater than 2,000 V or greater than 4,000 V. This potential difference describes an increase in the kinetic energy of the electrons within the beam tube compared to the kinetic energy with which the electrons strike the object.According to exemplary embodiments, a potential difference U 2-U 1 is considered to be greater than 20 V. The potential difference U 2-U 1 may be less than, for example, 30,000 V or 50,000 V. This potential difference corresponds to the kinetic energy with which the electrons of the electron beam strike the object.According to exemplary embodiments, an absolute value of a potential difference U 4-U 3 is considered to be less than 3,000 V. The potential difference U4-U3 can furthermore be less than 2,000 V, less than al 1,000 V or less than 500 V.This potential difference is the potential difference between the reflector plate and the converter. In particular, the electrical potentials of the reflector plate and of the converter can be the same and the potential difference U 4-U 3 can thus be zero.According to exemplary embodiments, |U3-U5|<3,000 V applies. This means that there is only a small potential difference between the reflector plate and the beam tube. In particular, the electrical potentials of the reflector plate and of the beam tube can be the same and the potential difference U 4-U 5 can thus be zero.According to exemplary embodiments, the electron beam microscope further comprises a first vacuum space, a second vacuum space, a pump arrangement and a compression stage diaphragm. During operation of the electron beam microscope, the pump arrangement evacuates the two vacuum spaces, wherein different gas pressures are maintained therein. A wall separating the two vacuum spaces comprises the compression stage diaphragm which has an opening through which the electron beam passes. The reflector plate can be provided on the compression stage diaphragm.Thus, a compression stage diaphragm provided for separating vacuum spaces along the electron beam can be easily used for detecting electrons generated by the electron beam on the object.In addition to the above-described electron detector comprising the reflector plate and the converter, the electron beam microscope can have one or more further electron detectors for detecting electrons generated on the object by the incident electron beam. These further electron detectors can also each comprise a converter which generates electrical or optical signals from electrons which strike the converter.Embodiments of the invention are explained in more detail below with reference to figures: FIG. 1 is a schematic sectional view showing an electron beam microscope according to an embodiment. FIG. 2 is a schematic sectional view showing a variant of a detector of the electron beam microscope shown in FIG. 1. FIG. 3 is a schematic sectional view of a part of an electron beam microscope according to another embodiment.An electron beam microscope 1 shown schematically in section in FIG. 1 comprises an electron beam source 3 which has an electron emitter 5 and an extractor electrode 7. An electrical potential U1 is supplied to the electron emitter 5 from a potential supply system 9, which can be part of a control system 11 of the electron beam microscope 1, via an electrical connection 12. An electrical potential U6 is supplied to the extractor electrode 7 from the potential supply system 9 via an electrical connection 8. The electrical potential U 1 can be, for example, 100 V, and the electrical potential U 6 can be, for example, 8,000 V. The potential difference between the electron emitter 5 and the extractor electrode 7 generates a strong electric field at a tip of the electron emitter 5, which extracts electrons from the electron emitter. The extracted electrons are accelerated toward the extractor electrode 7, and a part of the electrons passes through an opening 13 in the extractor electrode 7 to form, below the extractor electrode 7 as shown in FIG. 1, an electron beam 12 whose electrons move downward along a principal axis 15 of the electron beam microscope 1 in FIG. 1. A beam path of the electron beam 12 thus extends along the main axis 15.The electron beam microscope 1 further comprises a beam tube 17 having a first end 19 and a second end 21. The electrons of the electron beam 12 enter the beam tube 17 at the first end 19, pass through the beam tube and exit the beam tube 17 at the second end 21. The beam tube forms an electrode by an electrically conductive inner jacket, which electrode surrounds the electron beam between its entry into the beam tube 17 and the exit from the beam tube 17. A potential U5 is supplied to the beam tube 17 from the potential supply system 9 via an electrical connection 18. A potential difference U5-U1 between the beam tube 17 and the electron emitter 5 is, for example, 8,000 V, so that the electrons of the electron beam 12 are accelerated into the beam tube 17 and pass through it at a high speed as far as its second end 21. The potential U 5 of the beam tube 17 may be equal to the potential U 6 of the extractor electrode 7.After exiting from the beam tube 17, the electrons of the electron beam 12 strike an object 23 which is held on an object holder 25. An electrical potential U2 is supplied to the object holder 25 from the potential supply system 9 via an electrical connection 26. A potential difference U 2-U 1 defines the kinetic energy with which the electrons of the electron beam 12 impinge on the object 23. This kinetic energy is substantially lower than the kinetic energy of the electrons of the electron beam 12 within the beam tube 17, so that the electrons are decelerated after they exit from the beam tube 17 before they strike the object 23. The potential difference U2-U1 is, for example, 200 V or 2,000 V. The potential U2 can be, for example, the ground potential of the electron beam microscope.The electron beam microscope 1 further comprises an objective lens 27 which, as viewed perpendicularly to the main axis 15, is arranged between the electron beam source 3 and the object holder 25. The objective lens 27 comprises a coil 29 to which an excitation current can be supplied from the controller 11 for generating a magnetic field focusing the electron beam 12. The coil 29 lies within a magnetic yoke 31, which is rotationally symmetrical with respect to the main axis 15 and has a first pole end 33 and a second pole end 35. A gap is formed between the pole ends 33 and 35 so that magnetic fields generated by the coil 29 and running in the yoke 31 and emerging at the pole ends 33 and 35 act in a focusing manner on the electron beam 12. The maximum of the effect of the focusing magnetic field on the electron beam 12 lies, as seen perpendicular to the main axis 15, between the pole ends 33 and 35 within the gap between them.In order to collimate the electron beam 12 after it leaves the electron beam source 3, a collimator lens can be provided, for example, between the electron beam source 3 and the first end 19 of the beam tube 17, which collimator lens is not illustrated in FIG. 1.The electron beam 12 striking the object 23 at an object location 37 leads to electrons emerging from the object 23 at the object location 37. These electrons comprise electrons referred to as secondary electrons which, when they leave the surface of the object 23, have a kinetic energy of, for example, less than 50 electron volts. Furthermore, electrons, referred to as backscattered electrons, emerge from the object 23 at the object location 37, the energy of which electrons is substantially greater than the exemplary 50 electron volts and the kinetic energy of which can range up to the kinetic energy which the electrons of the electron beam 12 impinging on the object 23 have. Reference numeral 39 in FIG. 1 denotes an exemplary trajectory of an electron emerging from the object 23 at the object location 37, which electron is generated by the electron beam 12 at the object 23 and impinges on the objective lens 27 next to the beam tube 17. Reference numeral 41 in FIG. 1 shows the exemplary trajectory of an electron generated by the electron beam 12 at the point of incidence 17, which electron is accelerated at the second end 21 of the beam tube 17 into the beam tube 17 and moves within the beam tube 17 in the direction of the first end 19 of the beam tube 17.Such electrons are detected in the electron beam microscope 1 with a first electron detector 42. The first electron detector 42 comprises a reflector plate 43 which, viewed perpendicularly to the main axis 15, is arranged between the first end 19 and the second end 21 of the beam tube 17 next to the electron beam 12. The electron represented by the trajectory 41 impinges on the reflector plate. The reflector plate 43 can have, for example, a rotationally symmetrical shape with respect to the main axis 15 of a circular disk or of a conical jacket. The reflector plate 43 has a central hole 45 through which the electron beam 12 passes and does not obstruct it. However, the electron represented by the trajectory 41 moves at a distance from the main axis 12 and can therefore strike the reflector plate 43.The electrons striking the reflector plate 43 in turn generate secondary electrons and backscattered electrons in the material of the reflector plate 43 which move away from the reflector plate 43. Reference numeral 47 in FIG. 1 represents a trajectory of such an electron. A portion of the electrons generated at the reflector plate 43 impinges upon a converter 48 of the first electron detector 42. In the example described herein, the converter 48 is a scintillator 49 comprised of a scintillator material that generates light from electrons impinging upon or entering the scintillator material. The scintillator 49 can, for example, likewise have a shape of a circular disk which is rotationally symmetrical with respect to the main axis 15 and has a central hole 51 through which the electron beam 12 and the electrons generated at the object location 37 and impinging on the reflector plate 43 pass.In order for the electrons striking scintillator 49 to generate light, they must have a certain kinetic energy. In the example explained here, there is no potential difference between the reflector plate 43 and the scintillator 49, since they are both at the potential U5 of the beam tube 17. Then, it is substantially the backscattered electrons reflected at the reflector plate 43 and less the secondary electrons generated at the reflector plate 43, from which light is generated in the scintillator. Therefore, at least the surface of the reflector plate 43 is made of a material having heavy atoms such as gold to generate as large as possible a number of electrons of higher kinetic energy from electrons incident on the reflector plate 43 and incident on the scintillator 49. It is also conceivable to provide a potential difference between the reflector plate 43 and the scintillator 49 in order to increase the kinetic energy of the electrons striking the scintillator.Reference numeral 53 in FIG. 1 represents an exemplary trajectory of a light beam which is generated in the scintillator material of the scintillator 49 by the electron having the trajectory 47 striking the scintillator 49. This light is conducted in a light guide 55 optically coupled to the scintillator 49 to a light detector 57, which detects incident light and generates electrical signals corresponding to the detected light, which are output via a terminal 58 and fed to the controller 11 for processing.In addition to the first electron detector 42, the electron beam microscope 1 comprises a second electron detector 61 which comprises a converter 63 on which electrons generated by the electron beam 12 at the object location 37 can directly impinge, as is shown by an exemplary trajectory 65 of such an electron in FIG. 1. Converter 63 is a scintillator that produces light from incident electrons, which is directed through light guide 65 to light detector 67. An exemplary trajectory 69 represents the course of a light beam generated by the converter 63 towards the light detector 67 in FIG. 1. The light detector 67 generates electrical signals representing the intensity of the detected light, which are output to the controller 11 via a terminal 69.Electron detectors, such as the second electron detector 61, can be arranged at different positions of the electron beam microscope 1 in order to detect electrons generated by the electron beam 12 on the object 23. With the converter 63 of the second electron detector 61, such electrons are directly converted into detectable signals, such as the light generated with the scintillator. In the first electron detector 42, the electrons generated on the object 23 are not directly detected by the converter 49, but indirectly, by the electrons generated on the object 23 first striking the reflector plate 43, there generating back-scattered electrons, which are converted by the converter 49 into light which is detected by the light detector 57. Here, the reflector plate 43 may be disposed at positions of the electron beam microscope 1 where a converter for directly detecting the electrons generated on the object 23 cannot be disposed.In the example described here, the reflector plate 43 is attached to a compression stage diaphragm 71 which separates two vacuum spaces 73 and 75 of the electron beam microscope 1 from one another. The vacuum chamber 73 contains the object holder 25 and the object 23 as well as the converters 48 and 63 of the electron detectors 42 and 61 and other components of the electron beam microscope 1. the vacuum chamber 75 contains the electron beam source 3. the vacuum chambers 73 and 75 are delimited from the environment by a vacuum jacket 76, the vacuum chamber 73 is evacuated via a pump connection 77 provided on the vacuum jacket 76, to which a vacuum pump, not shown in FIG. 1, is connected, and the vacuum chamber 75 is evacuated by a pump connection 79 provided on the vacuum jacket 76, to which a vacuum pump, not shown in FIG. 1, is connected. The vacuum spaces 73 and 75 are separated from one another by a wall 81 into which the compression stage diaphragm 71 is fitted, which has an opening 83 through which the electron beam 12 passes and which is formed as a tube extending along the main axis 15 in order to provide a gas flow resistance which allows a better vacuum to be maintained in the vacuum space 75 in which the electron beam source 3 is arranged than in the vacuum space 73 in which the object 23 is arranged. The reflector plate 43 of the first electron detector 42 is directly attached to the step diaphragm 71. It would be difficult to attach a converter of a conventional electron detector directly to the compression diaphragm.FIG. 2 schematically shows a cross-sectional view of a part of an electron beam microscope with a variant of the first electron detector of the electron beam microscope shown in FIG. 1.A first electron detector 42 aof an electron beam microscope 1 aincludes a reflector plate 43 a, on which electrons 41 agenerated on an object strike and are reflected by the reflector plate 43 aas backscattered electrons 47 a. The backscattered electrons 47 acan strike a converter 48 awhich converts the incident electrons 47 ainto electrical signals. For this purpose, the converter 48 ais designed as a semiconductor detector 91, which generates electrical signals by the impinging electrons 47 a, which are output via a terminal 93 to a controller of the electron beam microscope 1 a. In contrast to the example explained with reference to FIG. 1, the electrons reflected at the reflector plate 43 aare not converted into light by the converter 48 abut directly into electrical signals. The semiconductor detector 91 may include, for example, a semiconductor diode, an avalanche diode, a multi-pixel avalanche diode (SiPM), or other semiconductor-based sensors. The reflector plate 45 aof the first electron detector 42 ahas an opening 45 acentred with respect to a main axis 15 a, through which the electron beam generated by an electron beam source can pass toward the object. Similarly, the semiconductor detector 91 of the first electron detector 42a has an opening 51a centered with respect to the main axis 15a, through which the electron beam can pass towards the object and through which the electrons coming from the object can pass towards the reflector plate. The converter 48a is disposed closer to the object than the reflector plate 45a.FIG. 3 schematically shows a cross-sectional view of a part of an electron beam microscope 1 b, wherein a first electron detector 42 band a third electron detector 85 of the electron beam microscope 1 are substantially illustrated in FIG. 3 and other components of the electron beam microscope 1 bare not illustrated in the figure. These other components of the electron beam microscope 1 bmay correspond to those of the electron beam microscope explained with reference to FIG. 1.In the electron beam microscope 1 b, an electron beam 12 bis generated by an electron beam source, not shown, which is directed at an object, not shown in FIG. 3. The electrons of the electron beam 12 bfiding on the object generate electrons there, which can be detected by the two electron detectors 57 band 85. Reference numeral 41 b shows in FIG. 3 by way of example a trajectory of an electron generated by the electron beam 12 bon the object, which trajectory impinges on a reflector plate 43 bof the first electron detector 42 b. Electrons incident on the reflector plate 43b generate secondary electrons and backscattered electrons in the material of the reflector plate 43b, which travel away from the reflector plate 43. Reference numeral 47b in FIG. 1 shows a trajectory of such an electron which impinges on a converter 48b of the first electron detector 42b. As in the electron beam microscope explained with reference to FIG. 1, light 53 bis generated in the converter 48 b, which is formed by a scintillator 49 b, which light enters a light guide 55 band is conducted therein to a light detector 57 b, which detects this light. At a terminal 58 b, the light detector 57 boutputs electrical signals corresponding to the detected light to a controller of the electron beam microscope 1 b.The second electron detector 85 comprises a scintillator 87 which has the shape of a circular disk surrounding the electron beam 12 band is coupled to a light guide 89. An electron arriving at scintillator 87 and coming from the object is illustrated in FIG. 3 by way of example by a trajectory 91. Light 93 is generated in scintillator 87 with the incident electron 91, and is conducted in light guide 89 to a light detector 95, which detects this light and outputs signals corresponding to the detected light via a terminal 97 to the controller of electron beam microscope 1 b.The electron striking scintillator 87 first passes through a first electrode 99 and then a second electrode 101 before reaching scintillator 87. The first electrode 99 and the scintillator 87 are at the same electrical potential, for example within a beam tube 17 b. The electrical potential of the second electrode 101 is adjustable and smaller than the electrical potential of the first electrode 99, so that only electrons whose kinetic energy is greater than a threshold value can pass through the second electrode 101. The threshold value is defined by the adjustable potential of the second electrode 101. An exemplary trajectory of an electron coming from the object, the kinetic energy of which is less than this threshold value, is denoted in FIG. 3 by the reference symbol 103. This electron passes through the first electrode 99, is delayed and reflected in the electric field between the first electrode 99 and the second electrode 101 since its kinetic energy is smaller than the threshold defined by the potential of the second electrode 101. The electron represented by the trajectory 91 has a kinetic energy before passing through the first electrode 99 which is greater than the threshold value, so that even after the delay in the electric field between the first electrode 99 and the second electrode 101 it still moves in the direction of the second electrode 101 and through it, whereupon this electron is accelerated again in the electric field between the second electrode 101 and the scintillator 87, impinges on the scintillator 87 and generates light 93 in this.Thus, by changing the potential of the second electrode 101 and determining the intensity of the light detected by the light detector 95, it is possible to measure the energy spectrum of the electrons generated on the object that reach the scintillator 87. The first electrode 99 and the second electrode 101 may be formed of a conductive mesh or mesh. Electric potentials are supplied to the electrodes 99 and 101 from the outside by the control of the electron beam microscope 1b.In order to shield the electron beam 12 bfrom being influenced by the electric fields generated between the first electrode 99 and the second electrode 101 and between the second electrode 101 and the scintillator 87, an electrically conductive tube 105 is provided, which passes through the two electrodes 99 and 101, the scintillator 87 and the light guide 89 centered with respect to a main axis 15 bof the electron beam microscope 1 b. The tube 105 is at the same electrical potential as the beam tube 17 b, for example.In order that the electrical potential of the tube 105 does not influence the electrical fields between the two electrodes 99 and 101 and between the second electrode 101 and the scintillator 87, an insulator 107 is provided which surrounds the tube 105 in the region between the first electrode 99 and the scintillator 87. Furthermore, a further insulator 109 is provided for this purpose, which surrounds the first electrode 99, the second electrode 101 and the scintillator 87 on the outside.Electrons coming from the object can strike scintillator 87 of second electron detector 85, which are at a distance from main axis 15 bwhen first electrode 99 is traversed that is greater than the outer radius of insulator 107. Thus, electrons cannot be detected by the second electron detector 85, which are at a distance from the main axis 15 bin the region of the first electrode 99 that is smaller than the outer radius of the insulator 107.In order to be able to detect at least those of these electrons whose distance from the main axis 15 bin the region of the second electrode 99 bis greater than the inner radius of the insulator 107, the reflector plate 43 bof the first electron detector 42 bis attached to an end face of the insulator 107 and of the tube 105 facing the object. Thus, electrons coming from the object can be detected by the first electron detector 42 b, the distance of which from the main axis 15 bin the region of the first electrode 99 bis greater than the inner radius and smaller than the outer radius of the insulator 107. The use of the first electron detector 42 bwith the reflector plate 43 bthus enables the detection of electrons which would otherwise, i.e. without the presence of the reflector plate 43 b, strike a component of the electron beam microscope 1 b, namely here the end face of the insulator 107, and would not be detectable.

Claims

An electron beam microscope comprising: an electron beam source (3) configured to generate an electron beam (12); an object holder (25) configured to holder an object at an object location (37) on which the electron beam (12) impinges; an objective lens (27) arranged between the electron beam source (3) and the object location (37) when viewed perpendicular to a beam path of the electron beam (12) and configured to focus the electron beam (12) at the object location (37); a beam tube (17) having an electrically conductive inner jacket into which the electron beam (12) enters at a first end (19) of the beam tube (17) and from which the electron beam (12) exits at a second end (21) of the beam tube (17); and a first detector (42) configured to detect electrons (41) generated by the electron beam (12) on the object (23); wherein the first detector (42) comprises: a reflector plate (43) which, when viewed perpendicularly to the beam path of the electron beam (12), is arranged between the first end (19) of the beam tube (17) and the second end (21) of the beam tube (17) within the beam tube (17) such that the electrons (41) generated on the object (23) strike the reflector plate (43) and are reflected by the latter, and a converter (48) which, when viewed perpendicularly to the beam path of the electron beam (12), is arranged between the reflector plate (43) and the object location (37) and which is configured to convert the electrons (47) reflected by the reflector plate (43) into electrical or optical signals.The electron beam microscope according to claim 1, wherein the converter (48), as viewed perpendicularly to the beam path of the electron beam (12), is arranged between the reflector plate (43) and the second end (21) of the beam tube (17) within the beam tube (17).The electron beam microscope according to claim 1 or 2, wherein the objective lens (27) for focusing the electron beam (12) provides a focusing magnetic field having a maximum when viewed along the electron beam (12); and wherein, when viewed perpendicular to the beam path (12) of the electron beam (12), the maximum is arranged between the first and second ends of the beam tube.Electron beam microscope according to Claim 3, wherein, as seen perpendicularly to the beam path of the electron beam (12), the reflector plate (43) is arranged between the first end (19) of the beam tube (17) and the maximum.The electron beam microscope according to claim 4, wherein, as viewed perpendicularly to the beam path of the electron beam (12), the converter (48) is arranged between the reflector plate (43) and the maximum.The electron beam microscope according to any one of claims 1 to 5, wherein at least one surface of the reflector plate (43) is made of a material comprising greater than 50 weight percent atomic numbers of greater than 45.The electron beam microscope according to any one of claims 1 to 6, wherein the converter (48a) is formed by a semiconductor detector (91) configured to generate electrical signals by the electrons (47a) reflected by the reflector plate (43a) and incident on the semiconductor detector (91).The electron beam microscope according to any one of claims 1 to 7, wherein the converter (48) comprises a scintillator material (49) configured to generate light (53) by the electrons (47) reflected by the reflector plate (43) and incident on the scintillator material (49); and wherein the first detector (42) further comprises a light detector (57) configured to generate electrical signals by the light (53) generated by the scintillator material (49).The electron beam microscope according to any one of claims 1 to 8, further comprising a potential supply system (9), wherein the potential supply system (9) is configured to supply a first electrical potential (U1) to the electron beam source (3), to supply a second electrical potential (U2) to the object holder (25), to supply a third electrical potential (U3) to the reflector plate (43), to supply a fourth electrical potential (U4) to the converter (48) and to supply a fifth electrical potential (U5) to the beam tube (17).The electron beam microscope according to claim 9, wherein U5-U2 > 500 V, wherein U2 represents the second electric potential and U5 represents the fifth electric potential.Electron beam microscope according to one of Claims 9 to 10, wherein U2-U1 > 20 V and / or U2-U1 < 30 000 V applies, wherein U1 represents the first electrical potential and U2 represents the second electrical potential.Electron beam microscope according to one of Claims 9 to 11, wherein |U4-U3|<3,000 V applies, wherein U3 represents the third electrical potential and U4 represents the fourth electrical potential.Electron beam microscope according to one of Claims 9 to 12, wherein |U3-U5|<3,000 V applies, wherein U3 represents the third electrical potential and U5 represents the fifth electrical potential.The electron beam microscope according to any one of claims 1 to 13, further comprising a first vacuum space (73), a second vacuum space (75), a pump arrangement and a compression stage diaphragm (71); wherein the pump arrangement is configured to maintain a gas pressure in the first vacuum space (73) during operation of the electron beam microscope, which gas pressure is different from a gas pressure in the second vacuum space (75); wherein the compression stage diaphragm (73) is arranged between the first and the second vacuum space and has an opening (83) through which the electron beam (12) passes; and wherein the compression stage diaphragm (71) comprises the reflector plate (43).Electron beam microscope according to one of Claims 1 to 14, further comprising a second detector (61) which comprises a converter (63) which, as seen along the electron beam (12), is arranged between the converter (48) of the first detector (42) and the object location (37) in such a way that the electrons (65) generated on the object (23) strike the latter, and which is configured to convert the electrons generated on the object into electrical or optical signals.

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