Particle beam device and method thereof

Abstract

A method for inspecting an object using a particle beam device (3), the method comprising generating a configuration of electrostatic and magnetic fields. The magnetic field is generated using a magnetic lens (41). The electric field is generated between a ring electrode (39) and the object (9), the ring electrode surrounding the symmetry axis (49) of the magnetic lens (41) in a ring-like manner. The angle β between the surface normal (25) of the object (9) and the symmetry axis (49) is greater than 20°, therefore, the electric fields are asymmetric. The asymmetric electric fields are used to separate trajectories (53, 61, 81) of electrons having different kinetic energies, for detecting the trajectories different detectors (63, 83) are provided. For example, two different detectors (63, 83) can then be used to generate a secondary electron image and a backscattered electron image.

Description

Technical Field

[0001] The present invention relates to a method for inspecting an object using a particle beam apparatus and a particle beam apparatus for performing the method. Background Technology

[0002] An electron beam microscope is an example of a particle beam apparatus. It includes an electron beam source for generating an electron beam that is directed towards the object to be examined. The interaction of electrons in the incident electron beam with the object causes electrons to be emitted from the object, and these emitted electrons are detected using a detector. These electrons are emitted from the object with different energies, and the intensity of the electrons emitted with different kinetic energies depends on the characteristics of the object at the incident position of the electron beam. If the object is scanned using an electron beam raster, and the intensity of the electrons generated in the process is recorded in a position-dependent manner, the obtained data represents an electron microscope image from which the characteristics of the examined object are clearly visible.

[0003] The particle beam is focused onto the surface of an object using provided magnetic and electric fields to scan the object with the smallest possible beam spot, thus achieving high spatial resolution. Particle optical lenses, which provide electrostatic and magnetic fields, are used to focus the electron beam. Electrons emitted from the object are also affected by these fields on their way to the detector, which can be specifically integrated into the particle optical lens.

[0004] In many cases, the object to be examined is arranged such that the electron beam is orthogonally incident on the object's surface. However, there are also cases where the electron beam is incident on the object's surface at an angle. This is, for example, when the intention is not only to examine the object with an electron microscope but also to treat it with, for example, an ion beam. In this case, an ion beam is generated near the electron microscope via an ion beam column, and this ion beam is directed to the same area of ​​the object that can also be scanned by the electron beam. In this context, it may be desirable to orient the object's surface such that the ion beam is orthogonally incident on the object's surface, and thus the electron beam of the electron beam microscope is incident at an angle on the object's surface.

[0005] It has been found that electron microscope images obtained with this configuration do not meet all expectations in terms of clarity and information value. Summary of the Invention

[0006] Accordingly, the problem addressed by the present invention is to provide a method for inspecting objects using a particle beam device, which improves upon and expands the possibilities of particle beam devices.

[0007] According to the present invention, a method for inspecting an object using a particle beam device includes: directing a particle beam to a position on the main surface of the object; and using particles from the particle beam incident on the object to generate electrons emitted from the main surface of the object. To detect the electrons emitted from the object, at least one electron detector having a first effective detection area is provided.

[0008] The method involves configuring an electrostatic and magnetic field near an object, whereby the configuration selectively influences electrons generated at the object, such that a portion of the generated electrons are incident on a first detection area, while the remainder are not. The method further includes generating a first particle microscope image using a detection signal. The detection signal is generated by electrons incident on the first detection area. The configuration of the electrostatic and magnetic fields is achieved by generating a current flowing through a coil in a magnetic lens. The magnetic lens comprises magnetic poles arranged rotationally symmetrically about its axis of symmetry, and the coil extends about the axis of symmetry of the magnetic lens. Further, the configuration of the electrostatic and magnetic fields is generated by applying a voltage between a ring electrode and the object, the ring electrode being arranged in a ring around the axis of symmetry of the magnetic lens.

[0009] According to an exemplary embodiment, the object includes a main surface whose surface normal intersects the axis of symmetry of the magnetic lens, and the minimum angle between the surface normal and the axis of symmetry is greater than 20°, particularly greater than 30°, and particularly greater than 40°.

[0010] The configuration of the generated electrostatic and magnetic fields can also be used to focus an electron beam passing through a magnetic lens along the axis of symmetry onto the main surface of an object, such that the electron beam is a particle beam that produces electrons emitted from the main surface.

[0011] According to an exemplary embodiment, the generated electrons are influenced by a configuration of electrostatic and magnetic fields in such a way that the electrons generated in this manner are accelerated and pass through an opening in the ring electrode. Specifically, the manner is such that electrons in a first portion of the electrons passing through the ring electrode are incident on a first detection region, while electrons in a second portion of the electrons passing through the ring electrode are not incident on the first detection region. This is possible because electrons emitted from the object travel along a curved trajectory, the path of which depends not only on the direction of electron emission from the object but also on the kinetic energy of the electrons emitted from the object. Therefore, proper positioning of the effective detection region allows for the detection of electrons with specific characteristics to a greater extent. For example, the effective detection region can be positioned such that electrons emitted from the object with specific kinetic energies are incident on the effective detection region in an increased proportion, thereby enabling the generated particle microscope image to represent certain characteristics of the object.

[0012] Electrons emitted from an object can be divided into two groups, for example, a first group whose electrons are emitted from the object with kinetic energy less than a threshold and a second group whose electrons are emitted from the object with kinetic energy greater than a threshold.

[0013] According to an exemplary embodiment, the first detection region is designed such that the centroid of the first detection region is spaced apart from the axis of symmetry, and the ratio of the current of the electrons in the first group of electrons in the first portion of electrons to the current of the electrons in the second group of electrons is greater than or less than the ratio of the current of the electrons in the first group of electrons to the current of the electrons in the second portion of electrons. This multiple can be greater than 1.5, particularly greater than 2.0, particularly greater than 5.0, and particularly greater than 10.

[0014] This means that the detection area is designed such that: the detection area primarily detects electrons in a first group of electrons emitted from the object with kinetic energy less than a threshold; or, in an alternative to this scheme, the detection area primarily detects electrons in a second group of electrons emitted from the object with kinetic energy greater than a threshold.

[0015] According to an exemplary embodiment, the first detection region can be designed such that the electrons incident upon it are primarily so-called backscattered electrons, or so-called secondary electrons. Accordingly, the resulting first particle microscopy image can be referred to as a backscattered electron image or a secondary electron image. Electrons emitted from an object with a kinetic energy less than 50 eV are conventionally referred to as secondary electrons. Electrons emitted from an object with a kinetic energy greater than 50 eV are typically referred to as backscattered electrons.

[0016] According to an exemplary embodiment, the particle beam apparatus may have other detection regions besides the first detection region. However, the first particle microscope image explained above is primarily generated based on the detection signals generated by the first detection region, while the detection signals generated by the other possible detection regions are not used at all or only used to a very small extent when generating the first particle microscope image. In particular, the number of detection signals used to generate the first particle microscope image and generated by the first detection region of the electron detector is at least 1.5 times the number of detection signals used to generate the first particle microscope image and generated by the other possible detection regions. The particle microscope image can be divided into multiple pixels. That is, it consists of multiple pixels. For example, each pixel has a specific brightness value. This brightness value is determined by the number of detection signals assigned to the pixel when recording the particle microscope image. The sum of the detection signals assigned to each pixel on all pixels in the image is the number of detection signals used to generate the first particle microscope image.

[0017] According to an exemplary embodiment, the centroid of the first detection region is at a distance greater than 0.1 times, and particularly greater than 0.2 times, the maximum distance of the first detection region from the axis of symmetry. This means that the first detection region is not designed to be symmetrical about the axis of symmetry, and is offset relative to the axis of symmetry, for example, in a direction transverse to the axis of symmetry.

[0018] According to an exemplary embodiment, the method further includes: providing a second effective detection region of the at least one electron detector; and generating a second particle microscopy image using a detection signal generated by electrons incident on the second detection region. In this case, the second effective detection region is designed such that at least a portion of the second portion of electrons passing through the annular electrode (i.e., some electrons that did not incident on the first detection region) are incident on the second detection region. In this case, for example, the first particle microscopy image may be a backscattered electron image, while the second particle microscopy image may be a secondary electron image. Alternatively, the second particle microscopy image may be a backscattered electron image, while the first particle microscopy image may be a secondary electron image.

[0019] According to an exemplary embodiment, the second detection region can also be designed such that the centroid of the second detection region is spaced apart from the axis of symmetry. In this case, the distance between the centroid of the second detection region and the axis of symmetry can be greater than 0.1 times, or particularly greater than 0.2 times, the maximum distance between the second detection region and the axis of symmetry.

[0020] According to an exemplary embodiment, the annular electrode is provided by the magnetic extreme end of a magnetic lens.

[0021] According to an exemplary embodiment, in addition to the particle beam, an ion beam is also generated using an ion source, wherein the ion beam does not pass through the magnetic lens and the ring electrode, but is incident on the main surface of the object. The ion beam is generated such that it is incident on the main surface of the object in a direction having a minimum angle greater than 20°, and particularly greater than 30°, with respect to the axis of symmetry. The ion beam can be used to alter the object by removing material from the object or depositing material onto the object through treatment with the ion beam. Attached Figure Description

[0022] The embodiments of the present invention will be described in more detail below with reference to the figures.

[0023] Figure 1 A schematic cross-sectional view of a particle beam apparatus according to a first embodiment is shown.

[0024] Figure 2 It shows Figure 1 A bottom view of the detection area of ​​the electron detector in a particle beam apparatus.

[0025] Figure 3 A schematic cross-sectional view of a particle beam apparatus according to a second embodiment is shown.

[0026] Figure 4 It shows Figure 3 A bottom view of a variant of the detection area of ​​the electron detector in a particle beam apparatus.

[0027] Figure 5 A schematic cross-sectional view of a particle beam apparatus according to a third embodiment is shown.

[0028] Figure 6 It shows Figure 5 A schematic bottom view of the electron detector in a particle beam apparatus. Detailed Implementation

[0029] Figure 1 An example of a particle beam device 1 is schematically depicted in cross-section. The particle beam device 1 includes an electron beam column 3 and an ion beam column 5. The ion beam column 5 generates an ion beam 7, which is directed to an object 9 attached to an object holder 11.

[0030] The ion beam column 5 includes an ion source 13 that emits ions (e.g., gallium ions). The ions emitted by the ion source 13 are accelerated by electrodes 15 and shaped to form an ion beam 7, which exits from the ion beam column 5 and can be incident on an object 9. The ion beam column 5 further includes deflection electrodes 17, which are controlled by a controller 19 of the particle beam device 1 to deflect the ion beam 7 so that the ion beam can be directed to selectable locations on the object, within a working area on the surface of the object 9.

[0031] Targeted manipulation of object 9 is performed using a controlled ion beam 7. For example, ions incident on object 9 are used to remove material from object 9. Additionally, process gases can be brought into the vicinity of object 9, which are activated by ions in the ion beam to create material deposits on object 9.

[0032] Electron beam column 3 is configured to observe manipulation of object 9 performed with ion beam 7. Therefore, electron beam column 3 is designed as an electron microscope that generates electron beam 21, which is directed towards object 9. Electrons incident on object 9 in electron beam 21 produce different types of electrons that exit object 9 and differ significantly in their kinetic energy and direction of exit. Some of the electrons exiting object 9 are detected by electron detectors of electron microscope 3 (described in detail below), for example, to generate electron microscope images from which the progress of manipulation of object 9 with ion beam 7 can be clearly seen.

[0033] Object 9 has a main surface 23, which extends substantially in plane 24. Figure 1 In the figure, the surface normal of the main surface 23 at the incident position of the ion beam 7 on the object 9 is provided by reference numeral 25. The angle α between the surface normal 25 and the direction of the ion beam 7 at the incident position of the ion beam 7 on the main surface 23 of the object 9 is at most a few degrees, such that the ion beam 7 is incident on the main surface 23 of the object 9 approximately orthogonally.

[0034] Even if the main surface of the object extends substantially along plane 24, it is not impossible for the object 9 to carry microstructures on its surface. For example, peaks and valleys may be formed on the surface of the object 9, with heights and depths of a few micrometers.

[0035] Electron microscope 3 includes an electron beam source 31 that generates an electron beam 21. A controller 19 supplies a potential U1 to the electron emitter 32 of the electron beam source 31. The controller 19 also supplies a potential U2 to the object 9 (in...). Figure 1 (The example shown is the ground potential). The difference between potential U1 and potential U2 determines the kinetic energy of the electrons in electron beam 21 incident on the object. This kinetic energy can range from 10 eV to 50 keV. The advantages achievable by the particle beam device 1 explained herein are particularly evident when the kinetic energy ranges from 0.5 keV to 20 keV, and more particularly from 0.8 keV to 2.5 keV.

[0036] Electron beam source 31 further includes extraction electrode 33, which extracts electrons constituting electron beam 21 from electron emitter 32 and shapes these electrons to form electron beam 21. Electrons in electron beam 21 are accelerated toward anode 35. Figure 1 In this configuration, the anode is positioned at the upper end of the beam tube 37. The controller 19 supplies a potential U3 to the anode 35 and the beam tube 37, causing electrons from the electron beam 21 to be accelerated through the anode 35 and enter the beam tube 37, passing through it longitudinally until they exit the beam tube 37 via the annular electrode 39. Figure 1 In this process, the annular electrode is formed at the lower end 40 of the beam tube 37. After exiting the beam tube 37 through the annular electrode 39, the electrons in the electron beam 21 are decelerated in the electric field between the annular electrode 39 at potential U3 and the object 9 at potential U2.

[0037] The electron microscope 3 includes a magnetic lens 41 for focusing an electron beam 21 onto the main surface 23 of an object 9. The magnetic lens 41 includes a coil 43 surrounding the electron beam 21 and supplied with an excitation current by a controller 19 to generate a magnetic field. This magnetic field is guided in a magnetic yoke 45 located within the magnetic lens 41. Figure 1In the cross-section, the magnetic yoke includes a first magnetic end 46 and a second magnetic end 47. The two magnetic ends 46 and 47 extend around the electron beam 21 and are arranged symmetrically about the axis of symmetry 49 of the magnetic lens 41, i.e., centrally about this axis of symmetry. The magnetic field generated by the coil 43, guided in the magnetic yoke 45, and emitted at the magnetic ends 46 and 47 can focus the electron beam 21. The second magnetic end 47 is also at a defined potential. Figure 1 In the example shown, the potential of the second magnetic pole 47 is the same as the potential U2 of the object 9, but the potential of the second magnetic pole 47 can also be different from the potential U2 of the object 9. In both cases, the potential of the second magnetic pole 47 is different from the potential U3 of the beam tube 37. The magnetic pole 47 is arranged in a ring around the axis of symmetry 49 of the magnetic lens 41 and acts as a ring electrode that influences the electron beam 21.

[0038] The angle β between the surface normal 25 and the axis of symmetry 49 is significantly different from zero and is greater than 20°, especially greater than 30°.

[0039] The electron microscope 3 further includes beam deflectors 51, which are activated by the controller 19 to deflect the electron beam 21 so that it is incident on the main surface 23 of the object 9 at a selectable incident position. Electrons generated by the incident electrons in the electron beam 21 onto the object 9 and emitted from the object and detected by the detector of the electron microscope 3 (described below) can then be captured in a manner corresponding to the respective incident position. Data recordings of the detected signal intensity when scanning a portion of the surface of the object 9 represent an electron microscope image of that portion of the object.

[0040] The electrons produced by the electrons in the electron beam 21 differ in the direction in which they exit the object 9 and in the kinetic energy they emit from the object 9. Figure 1 Exemplary trajectories of three different types of electrons emitted from object 9 are shown, wherein these three types are essentially different in terms of the kinetic energy of the electrons emitted from object 9 and the direction of the electrons emitted from object 9.

[0041] Figure 1Reference numeral 53 in the figures indicates an exemplary trajectory of backscattered electrons emitted from object 9, directed such that they pass through annular electrode 39 into beam tube 37 and are incident on detection region 55 of electron detector 56. In this case, the electron trajectory 53 is influenced by the electric fields between annular electrode 39 and annular electrode 47 and the main surface 23 of object 9, as well as the magnetic field of magnetic lens 41. The electric field that decelerates electrons in electron beam 21 between their emission from beam tube 37 through annular electrode 39 and their incident on surface 23 of object 9 correspondingly accelerates electrons emitted from object 9 and incident on detection region 55 of electron detector 56. The magnetic field generated by magnetic lens 41 and focusing electron beam 21 on surface 23 of object 9 also affects electrons emitted from object 9 and incident on detection region 55 of detector 56, because these electrons are collimated by the magnetic field, and therefore, backscattered electrons emitted from the object in a finite solid angle pass through annular electrode 39 and can reach detection region 55.

[0042] The electron detector 56 of the example explained herein also includes two electrodes 57 and 58, which are arranged between the object 9 and the detection region 55 and are each formed by a grid. Electrode 58 and the detection region 55 are both at a potential U3 of the beam tube 37, while electrode 57, arranged between electrode 58 and the detection region 55, is supplied with an adjustable potential U4 by controller 19. Therefore, electrons 53 arriving at the detection region 55 can be selected using electrode 57 by modifying the potential U4 based on the kinetic energy of the electrons.

[0043] Figure 1 Reference numeral 61 in the accompanying figure illustrates, by way of example, two trajectories of low-energy secondary electrons emitted from the main surface 23 of object 9 at two different angles. This is in contrast to backscattered electrons (whose trajectories are illustrated by way of example). Figure 1 Compared to trajectory 53 in the diagram, the low-energy secondary electrons are significantly more affected by the electric fields between the ring electrodes 39 and 47 and the surface 23 of the object. The electric fields between the ring electrodes 39 and 47 and the main surface 23 of the object are significantly asymmetrical about the axis of symmetry 49 in the lower region near the object 9 because the angle β between the surface normal 25 and the axis of symmetry 49 is greater than 20°.

[0044] exist Figure 1 In the illustration, the low-energy secondary electron 61 crosses the axis of symmetry 49 before or after passing through the ring electrode 39, and... Figure 1In the illustration, the direction moves upward to the right of the axis of symmetry 49. Here, low-energy secondary electrons are incident on the first detection region 63 of the electron detector 65. The first detection region 63 of the electron detector 65 is disposed on a scintillator body 67, which generates light from the electrons incident on the first detection region 63. This light generated in the scintillator body 67 is emitted in all possible spatial directions and will reach the photodetector 69. For this purpose, a light guide 71 is provided, which is optically coupled to the scintillator body 67 at one end and optically coupled to the photodetector 69 at the other end. Figure 1 Reference numeral 73 in the figures indicates two exemplary trajectories of light generated by the scintillator body 67 and reaching the photodetector 69. The light guide 71 has an aperture 75 centered about the axis of symmetry 49, which first allows electrons in the electron beam 21 to pass through to reach the object 9, and secondly allows electrons generated at the object 9 and reaching the detection region 55 of the electron detector 56 to pass through the light guide 71. Furthermore, in Figure 1 In the cross-sectional diagram shown, the light guide 71 includes a region 77 that widens from right to left in a wedge shape, and in this region, the surface of the light guide 71 is oriented such that light is reflected to the left and toward the photodetector 69 in the diagram.

[0045] Figure 1 Reference numeral 81 in the accompanying drawings indicates an exemplary trajectory of a backscattered electron emitted from object 9. Because this electron has a higher kinetic energy upon emission from object 9, it is less affected by the asymmetric electric field between the ring electrode 39 and the surface 23 of object 9 compared to the trajectory 61 of a low-energy secondary electron. Figure 1 In the illustration, backscattered electrons with trajectory 81 reach the left side of the axis of symmetry 49 and are incident on the second detection region 83 of the electron detector 65. The second detection region 83 is disposed on the scintillator body 85, which generates light through the incident electrons. The scintillator body 85 is also optically coupled to the light guide 71, so that the generated light can enter the light guide and reach the photodetector 87, which is also optically coupled to the light guide 71. Figure 1 Reference numeral 89 in the figure illustrates, by way of example, the trajectory of light generated in the scintillator body 85 and reaching the photodetector 87.

[0046] The second detection area 83 is disposed only on a portion of the surface of the scintillator body 85 facing the object 9. Another portion of this surface carries and is optically coupled to the scintillator body 67, which provides the first detection area for the electronic detector 65. Therefore, the scintillator body 67 is coupled to the light guide 71 via the scintillator body 85.

[0047] Scintillator bodies 67 and 85 are made of different scintillator materials that produce light of different wavelengths from incident electrons. A dichroic layer 91, suitable for this wavelength, is disposed in the light guide and reflects the light 73 produced by the scintillator body 67, so that the light does not reach the photodetector 87 but reaches the photodetector 69. The dichroic layer 91 allows the light 89 produced by the scintillator body 85 to pass through, so that the light reaches the photodetector 87 instead of being reflected to the photodetector 69.

[0048] Therefore, electrons incident on the first detection region 63 of the electron detector 65, which are low-energy secondary electrons, initially generate detection signals in the form of light 73. These detection signals are converted into electrical signals by the photodetector 69, and these electrical signals are read by the controller and used to generate a first particle microscope image. Similarly, electrons (backscattered electrons) incident on the second detection region 83 of the electron detector 65 initially generate detection signals in the form of light 89. These detection signals are converted into electrical signals by the photodetector 87, and these electrical signals are also read by the controller and used to generate a second particle microscope image.

[0049] The first-particle microscopy image and the second-particle microscopy image differ in the kinetic energy of the electrons emitted from object 9, and their detection signals are used to generate the image. The first-particle microscopy image can be referred to as a secondary electron image, while the second-particle microscopy image can be referred to as a backscattered electron image.

[0050] Backscattered electrons are incident on the first detection region 63 and the second detection region 83 to the same degree because the backscattered electrons are relatively less affected by the asymmetric electric field. Since the secondary electrons have significantly lower kinetic energy, they are relatively more affected by the asymmetric electric field and are essentially not incident on the second detection region 83. Therefore, the detection signal generated by the second detection region 83 is essentially determined by the incident backscattered electrons and can be used as a signal representing the intensity of the backscattered electrons.

[0051] Most of the secondary electrons are incident on the first detection region 63. Furthermore, the number of secondary electrons generated and entering the beam tube 37 is generally significantly greater than the number of backscattered electrons generated and entering the beam tube 37. Therefore, although backscattered electrons are also incident on the first detection region 63, the detection signal generated by the first detection region 63 is essentially dominated by the incident secondary electrons, and this signal can be used as a representation of the intensity of the secondary electrons.

[0052] Therefore, secondary electrons and backscattered electrons are two groups of electrons that differ in kinetic energy when they exit object 9. The separation of electrons exiting object 9 into two groups can be based on a kinetic energy threshold. For example, a conventional value of 50 eV can be used as the threshold.

[0053] The first detection region 63 and the second detection region 83 are designed such that the detection signal from the first detection region 63 represents the intensity of the secondary electron to the best possible extent, and the detection signal from the second detection region 83 represents the intensity of the backscattered electron to the best possible extent.

[0054] Specifically, the ratio of the current of the electrons in the first group of electrons incident on the first detection region 63 to the current of the electrons in the second group of electrons is greater than or less than the ratio of the current of the electrons in the first group of electrons incident on the second detection region 83 (but not on the first detection region 63) to the current of the electrons in the second group of electrons. This ratio can be particularly greater than 1.5, particularly greater than 2.0, particularly greater than 5.0, and particularly greater than 10.

[0055] The separation of the trajectories of electrons in the first group from those in the second group is achieved, in particular, by the electrostatic field generated between the annular electrodes 39 and 47 and the main surface 23 of the object 9. Because the main surface 23 of the object 9 is inclined, this electrostatic field is asymmetrical about the axis of symmetry 49. However, this electrostatic field is about... Figure 1 The attached diagrams are basically symmetrical.

[0056] The magnetic field of the magnetic lens 41 causes the electron's trajectory to undergo Larmor rotation around the axis of symmetry 49; therefore, the electron's trajectory cannot actually lie in a plane. (Larmor rotation is not illustrated.) Figure 1 The illustration of the trajectory in the attached plane is not accurate. This is due to the Larmor rotation, and... Figure 1 The schematic illustration differs from the actual representation; the first detection region 63 is not actually positioned to the right of the axis of symmetry 49, and the second detection region 83 is not actually positioned to the left of the axis of symmetry 49. The actual geometries of the first detection region 63 and the second detection region 83 are determined through optimization calculations to separate the two groups of electrons as well as possible. For example, the optimization calculations can be implemented in a manner that maximizes the aforementioned multiplier. For example, the optimization calculations can include ray tracing methods, in which the movement of a large number of electrons emitted from an object with different energies and directions is simulated. In this case, the forces acting on the electrons by electrostatic and magnetic fields are considered, so that the resulting trajectories also reproduce Larmor rotations.

[0057] Figure 2 A schematic bottom view of the first detection area 63 and the second detection area 83 of the electronic detector 65 is shown. It is clear that these two detection areas 63 and 83 are not about... Figure 1 The attached plan (represented by line II) is arranged symmetrically.

[0058] The following explains another embodiment of the particle beam device and its operation method. In this case, it is similar in structure or function to... Figure 1 and Figure 2 The components of the particle beam apparatus shown are provided with the same reference numerals, but with additional letters. To avoid repetition, not all details are described herein, but the differences from the foregoing embodiments are essentially explained. For a complete understanding of all details, reference should be made to the description of the corresponding foregoing embodiments and the introduction to this specification.

[0059] Figure 3 A particle beam apparatus 1a is schematically shown, which further includes an electron beam microscope 3a and an ion beam column 5a. The ion beam column 5a generates an ion beam 7a that is incident substantially orthogonally on the main surface 23a of an object 9a and can be guided to selectable locations on the object to remove material from the object or deposit material onto the object 9a.

[0060] Electron beam microscope 3a includes an electron beam source 31a for generating an electron beam 21a that enters a beam tube 37a, passes through the beam tube, and exits from the beam tube 37a at its lower end 40a to be incident on an object 9a. A scintillator arrangement 64 of an electron detector 65a is arranged between the lower end 40a of the beam tube and the object 9a and includes a central opening through which the electron beam 21a passes. A ring electrode 39a is arranged between the scintillator arrangement 64 and the object 9a, through which the electron beam 21a passes and then is incident on the object 9a.

[0061] The controller 19a supplies potential U3 to the bundle tube 37a.

[0062] The scintillator arrangement 64 is fixed to the sleeve 101, which surrounds the bundle tube 37a on the outside and is electrically insulated from the bundle tube 37a by the insulator 103. The controller 19a supplies a potential U5 to the sleeve 101, such that the scintillator arrangement 64 is also at a potential U5.

[0063] The annular electrode 39a is held in place by a sleeve 105 that surrounds the sleeve 101 and is electrically insulated from it by an insulator 107. The controller 19a supplies a potential U6 to the sleeve 105, so that the annular electrode is also at a potential U6.

[0064] According to the example, potential U3 equals 8 kV, potential U5 equals 9 kV, and potential U6 equals 10 kV. Other values ​​for potentials U3, U5, and U6 are also possible. Potentials U3, U5, and U6 can be used to set electric fields that first slow down and focus the electron beam 21a on its path toward object 9a, and secondly affect the electrons emitted from object 9a on their paths toward the various detection areas on the detector of electron microscope 3a, in such a way that different groups of electrons emitted from object 9a are primarily incident on different detection areas. By setting potentials U3, U5, and U6, these functions can be optimized for different targets.

[0065] The electron beam microscope 3a further includes a magnetic lens 41a having two coils 43a and 43a' arranged between three magnetic poles 46a, 47a, and 47a'. The magnetic poles 46a, 47a, and 47a' are arranged symmetrically about the axis of symmetry 49a of the magnetic lens 41.

[0066] Magnetic poles 46a, 47a, and 47a' are at potential U2, which is the ground potential, the same as that of object 9a.

[0067] Figure 4 The diagram schematically illustrates a bottom view of the scintillator arrangement 64 of the electron detector 65a. The scintillator arrangement 64 has a disk shape with a central opening. The scintillator arrangement 64 includes a first scintillator body 67a and a second scintillator body 85a, the first scintillator body providing a first detection region 63a of the electron detector 65a, and the second scintillator body providing a second detection region 83a of the electron detector 65a. The two detection regions 63a and 83a are designed such that different groups of electrons emitted from the object 9a (the groups differing in kinetic energy) are primarily incident on different detection regions 63a and 83a, as explained in more detail above.

[0068] Figure 3 Reference numeral 61a in the accompanying drawings illustrates, by way of example, two trajectories of low-energy secondary electrons that exit from the main surface 23a of the object 9a at two different angles. These secondary electrons along trajectories 61a are incident on the first detection region 63a and produce light in the scintillator body 67a.

[0069] Figure 3 The reference numeral 81a in the figure illustrates, by way of example, the trajectory of a backscattered electron emitted from the main surface 23a of the object 9a. This trajectory 81a is incident on the second detection region 83a and generates light in the scintillator body 85a.

[0070] Figure 3Reference numeral 73a in the figure indicates two exemplary trajectories of light generated by the scintillator body 67a and reaching the photodetector 69a of the electronic detector 65a. Figure 3 Reference numeral 89a in the accompanying drawings indicates an exemplary trajectory of light generated by scintillator body 85a and arriving at photodetector 87a of electronic detector 65a. The light generated by scintillator body 85a differs from the light generated by scintillator body 67a in wavelength because scintillator bodies 67a and 85a are made of different scintillator materials.

[0071] In this configuration, the light generated by the two scintillator bodies 67a and 85a is reflected by a mirror 111 arranged within the beam tube 37a. Along the path from the scintillator bodies 67a and 85a to the mirror 111, the light can be reflected once or multiple times from the tapered inner wall of the beam tube 37, a design that causes the light to be guided more intensely toward the mirror 111 with each reflection. The mirror 111 has a slit 75a formed by a small tube for the passage of the electron beam 21a.

[0072] After being reflected by mirror 111, light enters light guide 71a, in which a dichroic layer 91a is disposed; light generated by scintillator body 85a passes through the layer, so that the light reaches photodetector 87a, and light generated by scintillator body 67a is reflected from the layer, so that the light reaches photodetector 69a.

[0073] The first detection region 63a and the second detection region 85a of the electron detector 65a are further geometrically designed in terms of the scintillator arrangement such that, among the first group of electrons with kinetic energies below a threshold, the proportion of electrons incident on the second detection region 83a is less than the proportion of electrons incident on the first detection region 63a. The design of the detection regions 63a and 83a can be determined through optimization calculations, as explained above.

[0074] The optimal design for detection areas 63a and 83a can vary depending on the application.

[0075] In addition to electron detector 65a, electron microscope 3a also includes another electron detector 56a, wherein electrons emitted from object 9a and passing through the notch 75a of reflector 111 are incident on the detection area 55a of the other electron detector. Electron detector 56a includes two electrodes 57a and 58a to select the kinetic energy of electrons arriving at detection area 55a.

[0076] Figure 5The particle beam apparatus 1b is schematically shown, which further includes an electron beam microscope 3b and an ion beam column 5b. The ion beam column 5b generates an ion beam 7b that is incident substantially orthogonally on the main surface 23b of an object 9b and can be guided to selectable locations on the object.

[0077] The electron beam microscope 3b includes an electron beam source 31b for generating an electron beam 21b that enters a beam tube 37b, passes through the beam tube, and exits the beam tube 37b through an annular electrode 39b located at the lower end 40b of the beam tube 37b, so as to be incident on the object 9b.

[0078] The controller 19b of the particle beam device 1b supplies potential U3 to the beam tube 37b and the ring electrode 39b.

[0079] The electron beam 21b is focused by the magnetic lens 41b, and the electrons in the electron beam 21b are slowed down by an electrostatic field before they are incident on the object. The field is generated between the second magnetic pole 47b of the ring electrode 39b and the magnetic lens 41b, which acts as the ring electrode, and the main surface 23b of the object 9b, which is at ground potential together with the second magnetic pole 47b.

[0080] The electron microscope 3b further includes an electron detector 56b. The electron detector 56b includes two electrodes 57b and 58b to select the kinetic energy of electrons arriving at the detection region 55b of the electron detector. Figure 5 The reference numeral 53b in the attached figure indicates the trajectory of the backscattered electrons reaching the detection region 55b.

[0081] Although Figure 1 The detection areas 63 and 83 of the electron microscope 3 and Figure 3 The detection regions 63a and 83a of the electron microscope 3a are essentially arranged in the same plane oriented transversely to the axis of symmetry, but the electron microscope 3b further includes an electron detector 65b providing the first detection region 63b and an electron detector 65b' providing the second detection region 83b, wherein the detection regions 63b and 83b are arranged in different planes.

[0082] A first detection region 63b is disposed on a first scintillator body 67b, which is optically coupled to a light guide 71b to guide light generated by the scintillator body 67b to a photodetector 69b of an electronic detector 65b. A second detection region 83b is disposed on a second scintillator body 85b, which is optically coupled to a light guide 71b' to guide light generated by the second scintillator body 85b to a photodetector 87b of an electronic detector 65b'.

[0083] In this case, from the perspective of the electrons emitted from the object, the scintillator body 67b obscures a portion of the detection area of ​​the electron detector 65b', and therefore, the effective detection area 83b of the electron detector is smaller than the maximum possible detection area of ​​the electron detector due to being obscured by the scintillator body 67b.

[0084] Figure 6 A schematic bottom view of electronic detectors 65b and 65b' is shown.

[0085] from Figure 6 It is further evident that the electronic detector 65b is pivotable, as indicated by arrow 121. By pivoting the electronic detector 65b, the geometry of the effective detection areas 63b and 83b can be modified and adapted to specific operating conditions.

[0086] In summary, a method for examining objects using a particle beam device is thus proposed. This method includes a configuration for generating electrostatic and magnetic fields, wherein the magnetic field is generated using a magnetic lens, and the electric field is generated between a ring electrode and the object, the ring electrode being arranged in a ring around the axis of symmetry of the magnetic lens. The angle β between the surface normal of the object and the axis of symmetry is greater than 20°, thus the electric field is asymmetric. The asymmetric electric field is used to separate electron trajectories with different kinetic energies. Different detectors are provided for detecting these electron trajectories, and therefore, for example, two different detectors can be used to generate a secondary electron image and a backscattered electron image.

Claims

1. A method for inspecting an object using a particle beam device, comprising: Configurations that generate electrostatic and magnetic fields in the following ways: A current is generated flowing through a coil in a magnetic lens, the magnetic lens comprising magnetic poles arranged rotationally symmetrically about the axis of symmetry of the magnetic lens, and the coil surrounding the axis of symmetry of the magnetic lens. Apply a voltage between the following: A ring electrode, which is arranged in a ring around the axis of symmetry of the magnetic lens, and The object includes a main surface, the surface normal of which intersects the axis of symmetry of the magnetic lens, and the minimum angle between the surface normal and the axis of symmetry is greater than 20°. Provide a first effective detection area for at least one electronic detector; The particle beam is directed to a position on the main surface of the object, and the particles in the particle beam incident on the object are used to generate electrons emitted from the main surface of the object, wherein a first group of electrons emitted from the object are emitted with kinetic energy below a threshold, while a second group of electrons emitted from the object are emitted with kinetic energy above the threshold. The configuration of electrostatic and magnetic fields affects the generated electrons in such a way that these electrons generated in this way are accelerated and pass through the opening in the annular electrode, and electrons in a first portion of these electrons passing through the annular electrode are incident on the first detection area, while electrons in a second portion of these electrons passing through the annular electrode are not incident on the first detection area. The detection signal generated by these electrons incident on the first detection area is used to generate a first particle microscope image; The first detection area is designed to enable The centroid of the first detection area is spaced apart from the axis of symmetry, and The ratio of the current of the electrons in the first group of electrons in the first part to the current of the electrons in the second group of electrons is either greater than or less than the ratio of the current of the electrons in the first group of electrons in the second part of electrons; and Among them, the multiple is greater than 1.5, especially greater than 2.0, especially greater than 5.0, and especially greater than 10.

2. The method according to claim 1, wherein The number of detection signals used to generate the first particle microscope image and generated by the first detection region of the electron detector is greater than the number of detection signals used to generate the first particle microscope image and generated by other possible detection regions of the at least one electron detector, or at least 1.5 times greater.

3. The method according to claim 1 or 2, wherein The distance from the centroid of the first detection area to the axis of symmetry is greater than 0.1 times, and particularly greater than 0.2 times, the maximum distance from the first detection area to the axis of symmetry.

4. The method according to any one of claims 1 to 3, wherein The first-particle microscope image is a backscattered electron image or a secondary electron image.

5. The method according to any one of claims 1 to 4, further comprising: Provides a second effective detection area for the at least one electronic detector; as well as The detection signal generated by these electrons incident on the second detection area is used to generate a second particle microscope image; The second detection area is designed to enable At least a portion of the electrons in the second part of those electrons passing through the ring electrode are incident on the second detection area.

6. The method according to claim 5, wherein The second detection area is further designed such that the centroid of the second detection area is spaced apart from the axis of symmetry.

7. The method according to claim 6, wherein The distance from the centroid of the second detection area to the axis of symmetry is greater than 0.1 times, and particularly greater than 0.2 times, the maximum distance from the second detection area to the axis of symmetry.

8. The method according to any one of claims 5 to 7, wherein, The first particle microscopy image is a backscattered electron image, while the second particle microscopy image is a secondary electron image; or The second particle microscope image is a backscattered electron image, while the first particle microscope image is a secondary electron image.

9. The method according to any one of claims 5 to 8, wherein The first effective detection area and the second effective detection area are substantially arranged in the same plane oriented transversely to the axis of symmetry.

10. The method according to any one of claims 1 to 9, further comprising: The particle beam is generated using a particle beam source in such a way that the particle beam, directed to these locations on the main surface, passes through the magnetic lens and the annular electrode.

11. The method according to claim 10, wherein The particle beam is an electron beam.

12. The method according to any one of claims 1 to 11, further comprising: An ion beam is generated using an ion source in such a way that the ion beam directed to these locations on the main surface does not pass through the magnetic lens and the annular electrode, and the minimum angle between the beam direction of the ion beam incident on the main surface and the axis of symmetry is greater than 20°, and particularly greater than 30°.

13. The method according to claim 12, wherein The particle beam is an ion beam.

14. A particle beam apparatus configured to perform the method according to any one of claims 1 to 13.

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