METHOD FOR OPERATING A PARTICLE BEAM APPARATUS, COMPUTER PROGRAM PRODUCT AND PARTICLE BEAM APPARATUS FOR CARRYING OUT THE METHOD

Abstract

The rocking beam method is used to generate a first image of an object and a second image of the object. A control device sets the size and/or the shape of an opening and/or the position of an aperture unit of the particle beam apparatus, and/or at least one electrostatic and/or magnetic deflection unit of the particle beam apparatus for displacing the scanning region, in such a way that a first irradiation direction of the particle beam in the direction of the location on the surface of the object corresponds to a second irradiation direction of the particle beam in the direction of the location on the surface of the object, wherein the first irradiation direction is ascertained from the first image and wherein the second irradiation direction is ascertained from the second image.

Claims

1. A method for operating a particle beam apparatus for processing, imaging and/or analyzing an object, the method comprising: generating a particle beam using a beam generator of the particle beam apparatus, the particle beam having charged particles; selecting at least one value of at least one control parameter for controlling at least one functional unit of the particle beam apparatus using a control device; controlling the functional unit with the value of the control parameter using the control device of the particle beam apparatus, wherein the particle beam is guided along a first beam path of the particle beam apparatus from the beam generator in the direction of the object; guiding the particle beam to a location of a scanning region on the surface of the object using a first guide device provided for guiding the particle beam and a second guide device provided for guiding the particle beam, wherein, as viewed from the beam generator in the direction of the object, the first guide device is arranged on and/or in the particle beam apparatus first, followed by the second guide device, wherein the first guide device guides the particle beam away from an optical axis of the particle beam apparatus at a first angle to the optical axis, wherein the second guide device guides the particle beam in a direction of the optical axis at a second angle to the optical axis, wherein, when guiding the particle beam to the location, the first angle runs through a first predeterminable value range and the second angle runs through a second predeterminable value range; detecting first interaction particles and/or a first interaction radiation using at least one detector, wherein the first interaction particles and/or the first interaction radiation result/results from an interaction of the particle beam with the object when the particle beam is incident on the object; generating first detection signals using the detected first interaction particles and/or the detected first interaction radiation; generating a first image of the object using the first detection signals and using the control device; selecting at least one value of a further control parameter for controlling the functional unit; controlling the functional unit with the value of the further control parameter using the control device, wherein the particle beam is guided along a second beam path of the particle beam apparatus from the beam generator in the direction of the object; guiding the particle beam to the location on the surface of the object using the first guide device and the second guide device, wherein the first guide device guides the particle beam away from the optical axis at a third angle to the optical axis, wherein the second guide device guides the particle beam in the direction of the optical axis at a fourth angle to the optical axis, wherein, when guiding the particle beam to the location, the third angle runs through a third predeterminable value range and the fourth angle runs through a fourth predeterminable value range; detecting second interaction particles and/or a second interaction radiation using the detector, wherein the second interaction particles and/or the second interaction radiation result/results from an interaction of the particle beam with the object when the particle beam is incident on the object; generating second detection signals using the detected second interaction particles and/or the detected second interaction radiation; generating a second image of the object using the second detection signals and using the control device; and setting, using the control device, the size and/or shape of an opening and/or position of an aperture unit of the particle beam apparatus, and/or at least one electrostatic and/or magnetic deflection unit of the particle beam apparatus for displacing the scanning region such that a first irradiation direction of the particle beam in the direction of the location on the surface of the object corresponds to a second irradiation direction of the particle beam in the direction of the location on the surface of the object, wherein the first irradiation direction is ascertained from the first image and wherein the second irradiation direction is ascertained from the second image.

2. The method according to claim 1, wherein the value of the control parameter is a first value and wherein the value of the further control parameter is a second value, the method further comprising: using the control parameter as the further control parameter.

3. The method according to claim 1, wherein the first angle is used as the second angle and/or the third angle is used as the fourth angle.

4. The method according to claim 1, wherein the first predeterminable value ranges between 0 and 90, the second predeterminable value ranges between 0 and 90, the third predeterminable value ranges between 0 and 90, the fourth predeterminable value ranges between 0 and 90, the first predeterminable value range equals the second predeterminable value range, and/or the third predeterminable value range equals the fourth predeterminable value range.

5. The method according to claim 1, wherein the beam generator as is the functional unit in order to set a particle current of the particle beam supplied to the object, the aperture unit as is the functional unit in order to set a convergence angle of the particle beam, a first condenser lens of the particle beam apparatus is the functional unit, and/or a second condenser lens of the particle beam apparatus is the functional unit.

6. The method according to claim 1, wherein backscatter particles are detected as first interaction particles, backscatter particles are detected as second interaction particles, backscattered electrons are detected as first interaction particles, and/or backscattered electrons are detected as second interaction particles.

7. A non-transitory computer readable medium containing software which is loadable into a processor and which, when executed, causes a particle beam apparatus to perform the following steps: generating a particle beam using a beam generator of the particle beam apparatus, the particle beam having charged particles; selecting at least one value of at least one control parameter for controlling at least one functional unit of the particle beam apparatus using a control device; controlling the functional unit with the value of the control parameter using the control device of the particle beam apparatus, wherein the particle beam is guided along a first beam path of the particle beam apparatus from the beam generator in the direction of the object; guiding the particle beam to a location of a scanning region on the surface of the object using a first guide device provided for guiding the particle beam and a second guide device provided for guiding the particle beam, wherein, as viewed from the beam generator in the direction of the object, the first guide device is arranged on and/or in the particle beam apparatus first, followed by the second guide device, wherein the first guide device guides the particle beam away from an optical axis of the particle beam apparatus at a first angle to the optical axis, wherein the second guide device guides the particle beam in a direction of the optical axis at a second angle to the optical axis, wherein, when guiding the particle beam to the location, the first angle runs through a first predeterminable value range and the second angle runs through a second predeterminable value range; detecting first interaction particles and/or a first interaction radiation using at least one detector, wherein the first interaction particles and/or the first interaction radiation result/results from an interaction of the particle beam with the object when the particle beam is incident on the object; generating first detection signals using the detected first interaction particles and/or the detected first interaction radiation; generating a first image of the object using the first detection signals and using the control device; selecting at least one value of a further control parameter for controlling the functional unit; controlling the functional unit with the value of the further control parameter using the control device, wherein the particle beam is guided along a second beam path of the particle beam apparatus from the beam generator in the direction of the object; guiding the particle beam to the location on the surface of the object using the first guide device and the second guide device, wherein the first guide device guides the particle beam away from the optical axis at a third angle to the optical axis, wherein the second guide device guides the particle beam in the direction of the optical axis at a fourth angle to the optical axis, wherein, when guiding the particle beam to the location, the third angle runs through a third predeterminable value range and the fourth angle runs through a fourth predeterminable value range; detecting second interaction particles and/or a second interaction radiation using the detector, wherein the second interaction particles and/or the second interaction radiation result/results from an interaction of the particle beam with the object when the particle beam is incident on the object; generating second detection signals using the detected second interaction particles and/or the detected second interaction radiation; generating a second image of the object using the second detection signals and using the control device; and setting, using the control device, the size and/or shape of an opening and/or position of an aperture unit of the particle beam apparatus, and/or at least one electrostatic and/or magnetic deflection unit of the particle beam apparatus for displacing the scanning region such that a first irradiation direction of the particle beam in the direction of the location on the surface of the object corresponds to a second irradiation direction of the particle beam in the direction of the location on the surface of the object, wherein the first irradiation direction is ascertained from the first image and wherein the second irradiation direction is ascertained from the second image.

8. A particle beam apparatus for processing, imaging and/or analyzing an object, comprising: at least one beam generator that generates a particle beam with charged particles; at least one aperture unit for setting the particle beam; at least one functional unit for generating, setting, guiding and/or shaping the particle beam; at least one first guide device for guiding the particle beam; at least one second guide device for guiding the particle beam; at least one detector for detecting interaction particles and/or interaction radiation which result/results from an interaction of the particle beam with the object when the particle beam is incident on the object; at least one electrostatic and/or magnetic deflection unit; and at least one control device having a processor coupled to a non-transitory computer readable medium containing software which is loadable into the processor and which, when executed, causes the particle beam apparatus to perform the following steps: generating a particle beam using a beam generator of the particle beam apparatus, the particle beam having charged particles; selecting at least one value of at least one control parameter for controlling at least one functional unit of the particle beam apparatus using a control device; controlling the functional unit with the value of the control parameter using the control device of the particle beam apparatus, wherein the particle beam is guided along a first beam path of the particle beam apparatus from the beam generator in the direction of the object; guiding the particle beam to a location of a scanning region on the surface of the object using a first guide device provided for guiding the particle beam and a second guide device provided for guiding the particle beam, wherein, as viewed from the beam generator in the direction of the object, the first guide device is arranged on and/or in the particle beam apparatus first, followed by the second guide device, wherein the first guide device guides the particle beam away from an optical axis of the particle beam apparatus at a first angle to the optical axis, wherein the second guide device guides the particle beam in a direction of the optical axis at a second angle to the optical axis, wherein, when guiding the particle beam to the location, the first angle runs through a first predeterminable value range and the second angle runs through a second predeterminable value range; detecting first interaction particles and/or a first interaction radiation using at least one detector, wherein the first interaction particles and/or the first interaction radiation result/results from an interaction of the particle beam with the object when the particle beam is incident on the object; generating first detection signals using the detected first interaction particles and/or the detected first interaction radiation; generating a first image of the object using the first detection signals and using the control device; selecting at least one value of a further control parameter for controlling the functional unit; controlling the functional unit with the value of the further control parameter using the control device, wherein the particle beam is guided along a second beam path of the particle beam apparatus from the beam generator in the direction of the object; guiding the particle beam to the location on the surface of the object using the first guide device and the second guide device, wherein the first guide device guides the particle beam away from the optical axis at a third angle to the optical axis, wherein the second guide device guides the particle beam in the direction of the optical axis at a fourth angle to the optical axis, wherein, when guiding the particle beam to the location, the third angle runs through a third predeterminable value range and the fourth angle runs through a fourth predeterminable value range; detecting second interaction particles and/or a second interaction radiation using the detector, wherein the second interaction particles and/or the second interaction radiation result/results from an interaction of the particle beam with the object when the particle beam is incident on the object; generating second detection signals using the detected second interaction particles and/or the detected second interaction radiation; generating a second image of the object using the second detection signals and using the control device; and setting, using the control device, the size and/or shape of an opening and/or position of an aperture unit of the particle beam apparatus, and/or at least one electrostatic and/or magnetic deflection unit of the particle beam apparatus for displacing the scanning region such that a first irradiation direction of the particle beam in the direction of the location on the surface of the object corresponds to a second irradiation direction of the particle beam in the direction of the location on the surface of the object, wherein the first irradiation direction is ascertained from the first image and wherein the second irradiation direction is ascertained from the second image.

9. The particle beam apparatus according to claim 8, wherein the particle beam apparatus includes at least one scanning device for raster-scanning the particle beam over the object, and wherein the scanning device comprises includes the first guide device and the second guide device.

10. The particle beam apparatus according to claim 8, wherein the particle beam apparatus comprises includes at least one objective lens that focuses the particle beam on the object.

11. The particle beam apparatus according to claim 10, wherein the beam generator is a first beam generator and the particle beam is a first particle beam with first charged particles, wherein the objective lens is a first objective lens that focuses the first particle beam on the object, the particle beam apparatus further comprising: at least one second beam generator that generates a second particle beam with second charged particles; and at least one second objective lens that focuses the second particle beam on the object.

12. The particle beam apparatus according to claim 8, wherein the electrostatic and/or magnetic deflection unit includes one condenser lens or a plurality of condenser lenses.

13. The particle beam apparatus according to claim 8, wherein the particle beam apparatus is an electron beam apparatus and/or an ion beam apparatus.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0059] Further practical embodiments and advantages of the system described herein are described below in conjunction with the drawings, in which:

[0060] FIG. 1 shows a schematic illustration of a first embodiment of a particle beam apparatus according to the system described herein;

[0061] FIG. 2 shows a schematic illustration of a second embodiment of a particle beam apparatus according to the system described herein;

[0062] FIG. 2A shows a schematic illustration of a third embodiment of a particle beam apparatus according to the system described herein;

[0063] FIG. 3 shows a schematic illustration of a fourth embodiment of a particle beam apparatus according to the system described herein;

[0064] FIG. 4 shows a schematic illustration of an embodiment of a movable object stage according to the system described herein;

[0065] FIG. 5 shows a further schematic illustration of the embodiment of the movable object stage as shown in FIG. 4;

[0066] FIG. 6 shows a schematic illustration of an operation sequence of a first embodiment of the method according to the system described herein;

[0067] FIG. 7 shows a first schematic illustration of a course of a particle beam in different modes of operation of a particle beam apparatus according to the system described herein; and

[0068] FIG. 8 shows a second schematic illustration of a course of a particle beam in different modes of operation of a particle beam apparatus according to the system described herein.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

[0069] The system described herein will now be explained in more detail with particle beam apparatuses in the form of an SEM and in the form of a combination apparatus having an electron beam column and an ion beam column. Explicit reference is made to the fact that the invention can be used for any particle beam apparatus, in particular for any electron beam apparatus and/or any ion beam apparatus.

[0070] FIG. 1 shows a schematic illustration of an embodiment of a particle beam apparatus according to the system described herein in the form of an SEM 100. The SEM 100 includes a beam generator 1 having an electron source, an extraction electrode 2, a control electrode 3 and an anode 4. The anode 4 forms a source-side end of a beam guiding tube 21 of the SEM 100. The beam generator 1 is embodied as a thermal field emitter, for example. In an alternative, the beam generator 1 is embodied as a thermal tungsten emitter or as a LAB.sub.6 emitter, for example.

[0071] Electrons that emerge from the beam generator 1 form a primary electron beam. The electrons are accelerated to anode potential due to a potential difference between the beam generator 1 and the anode 4. The potential of the anode 4 for example is 1 kV to 30 KV positive in comparison with the potential of the beam generator 1, and so the electrons have a kinetic energy in the range between 1 keV and 30 keV.

[0072] As viewed in the direction of an objective lens 10 along an optical axis 20 starting from the anode 4, the SEM 100 includes a first condenser lens 5 first, followed by a second condenser lens 6. An aperture unit 7 is arranged in the beam guiding tube 21 between the first condenser lens 5 and the second condenser lens 6. In the SEM 100 shown in FIG. 1, the objective lens 10 is embodied as a magnetic lens and includes a pole piece 22 with a pole piece gap 23. A ring coil 11 for generating the magnetic field of the objective lens 10 is arranged in the pole piece 22.

[0073] As explained further above, the beam path of the particle beam depends on the mode of operation of the SEM 100. This is explained in detail further below.

[0074] As viewed in the direction of the objective lens 10 starting from the second condenser lens 6, a guide system having a first guide device in the form of a first deflection device 9 and having a second guide device in the form of a second deflection device 12 is arranged along the optical axis 20 of the SEM 100. The first deflection device 9 is arranged source side on the objective lens 10. By contrast, the second deflection device 12 is arranged on the beam guiding tube 21 object side within the objective lens 10. The first deflection device 9 and the second deflection device 12 are crossed beam deflection devices. In other words, both the first deflection device 9 and the second deflection device 12 are embodied in such a way that the deflection devices 9, 12 deflect the primary electron beam in two directions which are not parallel to each other and are aligned at right angles to the direction of the optical axis 20. For example, the first deflection device 9 and/or the second deflection device 12 is/are embodied as a magnetic deflection device(s). In particular, the first deflection device 9 and/or the second deflection device 12 accordingly each include/includes, for example, four air coils that are arranged around the optical axis 20 of the SEM 100. In addition to that or in an alternative, provision is made for the first deflection device 9 and/or the second deflection device 12 to be embodied as an electrostatic deflection device(s). In particular, the first deflection device 9 and/or the second deflection device 12 accordingly each include/includes, for example, four electrodes which are arranged around the optical axis 20 of the SEM 100 and to which different electrostatic potentials can be applied.

[0075] The objective lens 10 is arranged on a sample chamber 13. In particular, the objective lens 10 protrudes through an opening of the sample chamber 13 into an interior of the sample chamber 13. A movable object stage 19 is arranged in the interior of the sample chamber 13. An object 15 can be arranged on the object stage 19.

[0076] Using the objective lens 10, the primary electron beam generated by the beam generator 1 and shaped using the first condenser lens 5 and/or the second condenser lens 6 is focused in an object plane 16. Suitable excitations of the first deflection device 9 and the second deflection device 12 ensure that the primary electron beam is deflectable perpendicular to the optical axis 20 of the SEM 100 in the object plane 16 such that the surface of the object 15 arranged in the object plane 16 can be raster-scanned by different deflections of the primary electron beam. In the process, the electrons of the primary electron beam interact with the object 15. As a consequence of the interaction, electrons in particular are emitted by the object 15 (so-called secondary electrons), and electrons of the primary electron beam are backscattered (so-called backscattered electrons). The secondary electrons and the backscattered electrons are detected and used for image generation. An image representation of the object 15 to be examined is thus obtained. Furthermore, interaction radiation, for example x-ray radiation or cathodoluminescence, is generated during the interaction, and the interaction radiation is detected and subsequently evaluated in order to analyse the object 15.

[0077] For the detection of the aforementioned interaction particles and/or aforementioned interaction radiation, a first detector unit 14 is for example arranged in the sample chamber 13. In addition to that or in an alternative, a second detector unit 8 for detecting the aforementioned interaction particles is for example arranged in the beam guiding tube 21 in the region between the first deflection device 9 and the second condenser lens 6.

[0078] For example, in the embodiment of the SEM 100 shown in FIG. 1, a pressure stage aperture mount 17 is provided, which can be arranged on the pole piece 22 of the objective lens 10 projecting into the sample chamber 13. For example, the pressure stage aperture mount 17 includes a pressure stage aperture unit having an aperture 18. Further pressure stage aperture units can be arranged, for example, within the beam guiding tube 21 of the SEM 100. These are not shown in FIG. 1. FIG. 1 does not show vacuum pumps either, the latter being desired, for example, for generating and maintaining the desired vacuum within the beam guiding tube 21 and the sample chamber 13 for the operation of the SEM 100.

[0079] For example, the pressure stage aperture mount 17 is not mandatory if the SEM 100 is intended to be operated under high vacuum in the sample chamber 13, and so the pressure stage aperture mount 17 can therefore be removed from the pole piece 22 of the objective lens 10. Then again, if the SEM 100 is for example intended to be operated at relatively high pressure in the sample chamber 13 (pressures in the range of about 1 to 3000 Pa), then the pressure stage aperture mount 17 should be mounted on the pole piece 22 of the objective lens 10 such that a sufficiently good vacuum can be maintained within the beam guiding tube 21 by differential pumping, despite the higher pressure in the sample chamber 13. In the event of a mounted pressure stage aperture mount 17, the edge of the aperture 18 within the pressure stage aperture mount 17 for example leads to a trimming of the image field which can be raster-scanned in the object plane 16.

[0080] In particular, the first detector unit 14, the second detector unit 8, the first deflection device 9 and the second deflection device 12 are connected to a control device 123, which includes a monitor 124. The control device 123 processes detection signals generated by the first detector unit 14 and the second detector unit 8 and displays the signals in the form of images on the monitor 124. The control device 123 also includes a database 126, in which data are stored and from which data are read out. Moreover, the control device 123 is connected to further units of the SEM 100. This is not illustrated in detail in FIG. 1.

[0081] The control device 123 of the SEM 100 includes a processor 127. A computer program product having a program code which, when executed, carries out a method for operating the SEM 100 is loaded in the processor 127. This is explained in detail further below.

[0082] In the SEM 100, it is possible to set a distance A using the control device 123 of the SEM 100. The distance A is given either (a) by an object distance between an outer boundary of the objective lens 10 of the SEM 100 and the object 15 or (b) by a focal plane distance between the outer boundary of the objective lens 10 of the SEM 100 and a focal plane of the objective lens 10. The aforementioned distance A according to case (a) or case (b) is also referred to as working distance. For example, the distance A in case (a) is set by moving the object stage 19 and/or moving the objective lens 10 using a movement device 25. In particular, the distance A in case (b) is set by varying an excitation of the objective lens 10 along the optical axis 20 of the SEM 100.

[0083] FIG. 2 shows a schematic illustration of a further SEM 100. The further SEM 100 includes a first beam generator in the form of an electron source 101, which is embodied as a cathode. Furthermore, the further SEM 100 is provided with an extraction electrode 102 and with an anode 103, which is placed onto one end of a beam guiding tube 104 of the further SEM 100. For example, the electron source 101 is embodied as a thermal field emitter. However, the invention is not restricted to such an electron source 101. Rather, any electron source suitable for the invention can be used.

[0084] Electrons emerging from the electron source 101 form a primary electron beam. The electrons are accelerated to anode potential owing to a potential difference between the electron source 101 and the anode 103. In the embodiment shown in FIG. 2, the anode potential is 100 V to 35 kV, for example 5 kV to 15 kV, in particular 8 kV, relative to a ground potential of a housing of a sample chamber 120. However, the anode potential could alternatively also be at ground potential.

[0085] Two condenser lenses, specifically a first condenser lens 105 and a second condenser lens 106, are arranged on the beam guiding tube 104. As viewed in the direction of a first objective lens 107 starting from the electron source 101, the first condenser lens 105 is arranged first in this case, followed by the second condenser lens 106. Explicit reference is made to the fact that further embodiments of the further SEM 100 may include only a single condenser lens. A first aperture unit 108 is arranged between the anode 103 and the first condenser lens 105. Together with the anode 103 and the beam guiding tube 104, the first aperture unit 108 is at a high-voltage potential, specifically the potential of the anode 103, or connected to ground. The first aperture unit 108 includes numerous first apertures 108A, one of which is depicted in FIG. 2. For example, two first apertures 108A are present. Each one of the numerous first apertures 108A has a different aperture diameter. Using an adjusting mechanism (not shown), it is possible to set a desired first aperture 108A onto an optical axis OA of the further SEM 100. Explicit reference is made to the fact that, in further embodiments, the first aperture unit 108 can be provided only with a single first aperture 108A and therefore, an adjusting mechanism cannot be provided. The first aperture unit 108 is then embodied to be stationary. A stationary second aperture unit 109 is arranged between the first condenser lens 105 and the second condenser lens 106. In an alternative, provision is made for the second aperture unit 109 to be movable.

[0086] As explained further above, the beam path of the particle beam depends on the mode of operation of the further SEM 100. This is explained in detail further below.

[0087] The first objective lens 107 includes pole pieces 110, in which a drilled hole is formed. The beam guiding tube 104 is guided through the drilled hole. A coil 111 is arranged in the pole pieces 110.

[0088] An electrostatic retardation device is arranged in a lower region of the beam guiding tube 104. The electrostatic retardation device includes a single electrode 112 and a tube electrode 113. The tube electrode 113 is arranged at an end of the beam guiding tube 104 that faces an object 125 arranged on a movable object holder 114.

[0089] Together with the beam guiding tube 104, the tube electrode 113 is at the potential of the anode 103, while the single electrode 112 and the object 125 are at a lower potential in relation to the potential of the anode 103. In the present case, the lower potential is the ground potential of the housing of the sample chamber 120. In this way, the electrons of the primary electron beam can be decelerated to a desired energy which is desired for examining the object 125.

[0090] The object 125 and the single electrode 112 can also be at different potentials and potentials that differ from ground. This makes it possible to set the location of the retardation of the primary electron beam in relation to the object 125. For example, imaging aberrations become smaller if the retardation is carried out quite close to the object 125.

[0091] The further SEM 100 furthermore includes a guide system having a first guide device in the form of a first deflection device 130 and having a second guide device in the form of a second deflection device 115. The first deflection device 130 is arranged source side within the first objective lens 107. By contrast, the second deflection device 115 is arranged on the beam guiding tube 104 object side within the first objective lens 107. The first deflection device 130 and the second deflection device 115 are crossed beam deflection devices. In other words, both the first deflection device 130 and the second deflection device 115 are embodied in such a way that the deflection devices 130, 115 deflect the primary electron beam in two directions which are not parallel to each other and are aligned at right angles to the direction of the optical axis OA of the further SEM 100. For example, the first deflection device 130 and/or the second deflection device 115 is/are embodied as a magnetic deflection device(s). In particular, the first deflection device 130 and/or the second deflection device 115 accordingly each include/includes, for example, four air coils that are arranged around the optical axis OA of the further SEM 100. In addition to that or in an alternative, provision is made for the first deflection device 130 and/or the second deflection device 115 to be embodied as an electrostatic deflection device(s). In particular, the first deflection device 130 and/or the second deflection device 115 accordingly each include/includes, for example, four electrodes which are arranged around the optical axis OA of the SEM 100 and to which different electrostatic potentials can be applied. Using the first deflection device 130 and the second deflection device 115, the primary electron beam is deflected and can be scanned (or raster-scanned) over the object 125. In the process, the electrons of the primary electron beam interact with the object 125. The interaction gives rise to interaction particles, which are detected. In particular, electrons emitted from the surface of the object 125so-called secondary electronsor electrons of the primary electron beam backscatteredso-called backscattered electronsare interaction particles.

[0092] A detector arrangement that includes a first detector 116 and a second detector 117 is arranged in the beam guiding tube 104 for the purpose of detecting the secondary electrons and/or the backscattered electrons. In this case, the first detector 116 is arranged source side along the optical axis OA, while the second detector 117 is arranged object side along the optical axis OA in the beam guiding tube 104. The first detector 116 and the second detector 117 are arranged offset from one another in the direction of the optical axis OA of the SEM 100. Both the first detector 116 and the second detector 117 have a respective passage opening, through which the primary electron beam can pass. The first detector 116 and the second detector 117 are approximately at the potential of the anode 103 and the beam guiding tube 104. The optical axis OA of the SEM 100 runs through the respective passage openings.

[0093] The second detector 117 serves mainly for detection of secondary electrons. Upon emergence from the object 125, the secondary electrons initially have a low kinetic energy and random directions of motion. The secondary electrons are accelerated in the direction of the first objective lens 107 using the strong extraction field emanating from the tube electrode 113. The secondary electrons enter the first objective lens 107 approximately in parallel. The beam diameter of the beam of the secondary electrons remains small even in the first objective lens 107. The first objective lens 107 then has a strong effect on the secondary electrons and generates a comparatively short focus of the secondary electrons with sufficiently steep angles to the optical axis OA, and so the secondary electrons diverge significantly from one another downstream of the focus and are incident on the active area of the second detector 117. By contrast, only a small proportion of electrons backscattered at the object 125i.e. backscattered electrons with a relatively high kinetic energy in comparison with the secondary electrons upon emergence from the object 125are detected by the second detector 117. The high kinetic energy and the angles of the backscattered electrons to the optical axis OA upon emergence from the object 125 have the effect that a beam waist, i.e., a beam region of minimal diameter, of the backscattered electrons lies in the vicinity of the second detector 117. A large portion of the backscattered electrons passes through the through opening of the second detector 117. Therefore, the first detector 116 substantially serves to detect the backscattered electrons.

[0094] In a further embodiment of the further SEM 100, the first detector 116 can be designed to also have an opposing field grid 116A. The opposing field grid 116A is arranged on the side of the first detector 116 directed toward the object 125. With respect to the potential of the beam guiding tube 104, the opposing field grid 116A has a negative potential such that only backscattered electrons with a high kinetic energy pass through the opposing field grid 116A to the first detector 116. In addition to that or in an alternative, the second detector 117 includes a further opposing field grid, which has an analogous design to the aforementioned opposing field grid 116A of the first detector 116 and has an analogous function.

[0095] Further, in the sample chamber 120 the further SEM 100 includes a chamber detector 119, for example an Everhart-Thornley detector or an ion detector, which has a metal-coated detection surface that blocks light.

[0096] The detection signals generated by the first detector 116, the second detector 117 and the chamber detector 119 are used to generate an image or images of the surface of the object 125.

[0097] Explicit reference is made to the fact that both the apertures of the first aperture unit 108 and of the second aperture unit 109 and the passage openings in the first detector 116 and in the second detector 117 are depicted in exaggerated fashion. The passage openings in the first detector 116 and in the second detector 117 have an extent perpendicular to the optical axis OA in the range of 0.5 mm to 5 mm. For example, the passage openings are of circular design and have a diameter in the range of 1 mm to 3 mm perpendicular to the optical axis OA.

[0098] The second aperture unit 109 is configured as a pinhole aperture unit in the embodiment illustrated in FIG. 2 and is provided with a second aperture 118 for the passage of the primary electron beam, which has an extent in the range of 5 m to 500 m, for example 35 m. In an alternative, provision is for example made in a further embodiment for the second aperture unit 109 to be provided with a plurality of apertures that are able to be mechanically shifted to the primary electron beam or able to be reached by the primary electron beam using electrical and/or magnetic deflection elements. For example, the second aperture unit 109 is designed as a pressure stage aperture unit. In one embodiment, the second aperture unit 109 separates a first region, in which the electron source 101 is arranged and in which there is an ultra-high vacuum (10.sup.7 hPa to 10.sup.12 hPa), from a second region, which has a high vacuum (10.sup.3 hPa to 10.sup.7 hPa). The second region in this exemplary embodiment is the intermediate pressure region of the beam guiding tube 104, which leads to the sample chamber 120.

[0099] For example, the sample chamber 120 can be under or near atmospheric pressure or is under vacuum in a further embodiment. To generate the vacuum, a pump (not depicted) in particular is arranged on the sample chamber 120. For example, in the embodiment shown in FIG. 2, the sample chamber 120 is operated in a first pressure range or in a second pressure range. In particular, provision is made for the first pressure range to include only pressures of less than or equal to 10.sup.3 hPa and for the second pressure range to include only pressures of greater than 10.sup.3 hPa. To ensure these pressure ranges, the sample chamber 120 is for example vacuum-sealed.

[0100] The object holder 114 is arranged on an object stage 122. The object stage 122 is designed to be movable in three directions arranged perpendicular to one another, specifically in an x-direction (first stage axis), in a y-direction (second stage axis) and in a z-direction (third stage axis). Moreover, the object stage 122 can be rotated about two axes of rotation (axes of rotation of the stage) which are arranged perpendicular to one another. The invention is not restricted to the aforementioned object stage 122. Rather, the object stage 122 may have a different number of translational movement axes and axes of rotation, along which or about which the object stage 122 can move. For example, a further axis is aligned in the z-direction, along which or with which a eucentric height can be set.

[0101] The further SEM 100 also includes a third detector 121 arranged in the sample chamber 120. More precisely, the third detector 121 is arranged downstream of the object stage 122, as viewed from the electron source 101 along the optical axis OA. The object stage 122, and hence the object holder 114, can be rotated in such a way that the primary electron beam can radiate through the object 125 arranged on the object holder 114. When the primary electron beam passes through the object 125 to be examined, the electrons of the primary electron beam interact with the material of the object 125 to be examined. The electrons passing through the object 125 to be examined are detected by the third detector 121.

[0102] Arranged on the sample chamber 120 is a radiation detector 500, which is used to detect interaction radiation, for example x-ray radiation and/or cathodoluminescence, generated when the primary electron beam is incident on the object 125. The radiation detector 500, the first detector 116, the second detector 117 and the chamber detector 119 are connected to a control device 123, which includes a monitor 124. The third detector 121 is also connected to the control device 123. This is not shown for reasons of clarity. The control device 123 processes detection signals that are generated by the first detector 116, the second detector 117, the chamber detector 119, the third detector 121 and/or the radiation detector 500 and displays said detection signals in the form of images on the monitor 124.

[0103] The control device 123 also includes a database 126, in which data are stored and from which data are read out. Further, the control device 123 is connected to the guide system, which includes the first deflection device 130 and the second deflection device 115. Moreover, the control device 123 is connected to further units of the further SEM 100. This is not shown in detail for reasons of clarity.

[0104] The control device 123 of the further SEM 100 includes a processor 127. A computer program product having a program code which, when executed, carries out a method for operating the further SEM 100 is loaded in the processor 127. This is explained in detail further below.

[0105] In the further SEM 100, it is possible to set a distance A using the control device 123 of the further SEM 100. The distance A is given either (a) by an object distance between an outer boundary of the first objective lens 107 of the further SEM 100 (e.g. the single electrode 112) and the object 125 or (b) by a focal plane distance between the outer boundary of the first objective lens 107 of the further SEM 100 and a focal plane of the first objective lens 107. The aforementioned distance A according to case (a) or case (b) is also referred to as working distance. For example, the distance A in case (a) is set by moving the object stage 122 and/or moving the first objective lens 107 using a movement device 25. For example, the distance A in case (b) is set by varying an excitation of the first objective lens 107 along the optical axis OA of the further SEM 100.

[0106] FIG. 2A shows a further embodiment of a yet further SEM 100, which is based on the embodiment of the further SEM 100 as shown in FIG. 2. Therefore, reference is made to the explanations given above, which also apply here. In contrast to the embodiment as shown in FIG. 2, the embodiment as shown in FIG. 2A does not include a second condenser lens 106. Rather, a first deflection unit 131 is arranged source side on the second aperture unit 109 and a second deflection unit 132 is arranged object side on the second aperture unit 109. For example, the first deflection unit 131 and/or the second deflection unit 132 is/are embodied as an electrostatic and/or magnetic deflection unit(s).

[0107] FIG. 3 shows a particle beam apparatus in the form of a combination apparatus 200. The combination apparatus 200 includes two particle beam columns. Firstly, the combination apparatus 200 is provided with the further SEM 100, as shown in FIG. 2, albeit without the sample chamber 120. Rather, the further SEM 100 is arranged on a sample chamber 201. The sample chamber 201 is under vacuum. To generate the vacuum, a pump (not shown) is arranged on the sample chamber 201. For example, in the embodiment shown in FIG. 3, the sample chamber 201 is operated in a first pressure range or in a second pressure range. For example, the first pressure range includes only pressures of less than or equal to 10.sup.3 hPa, and the second pressure range includes only pressures of greater than 10.sup.3 hPa. To ensure these pressure ranges, the sample chamber 201 is for example vacuum-sealed.

[0108] Arranged in the sample chamber 201 is the chamber detector 119 which for example is embodied in the form of an Everhart-Thornley detector or in the form of an ion detector and has a metal-coated detection surface that blocks light. Further, the third detector 121 is arranged in the sample chamber 201.

[0109] The further SEM 100 serves to generate a first particle beam, specifically the primary electron beam described above, and includes the optical axis mentioned above, which is provided with the reference sign 709 in FIG. 3 and is also referred to as first beam axis below. Secondly, the combination apparatus 200 is provided with an ion beam apparatus 300 likewise arranged on the sample chamber 201. The ion beam apparatus 300 likewise has an optical axis, which is provided with the reference sign 710 in FIG. 3 and is also referred to as second beam axis below.

[0110] As explained above, the beam path of the primary electron beam along the first beam axis 709 and/or the beam path of a second particle beam (an ion beam) along the second beam axis 710 are/is dependent on the mode of operation of the combination apparatus 200. This is explained in detail further below.

[0111] The further SEM 100 is arranged vertically in relation to the sample chamber 201. By contrast, the ion beam apparatus 300 is arranged in a manner inclined at an angle of approx. 0 to 90 to the further SEM 100. For example, an arrangement at approx. 50 is shown in FIG. 3. The ion beam apparatus 300 includes a second beam generator in the form of an ion beam generator 301. Ions, which form a second particle beam in the form of an ion beam, are generated by the ion beam generator 301. The ions are accelerated using an extraction electrode 302 at a predeterminable potential. The second particle beam then passes through an ion optical unit of the ion beam apparatus 300, the ion optical unit having a condenser lens 303 and a second objective lens 304. The second objective lens 304 ultimately generates an ion probe, which is focused on the object 125 arranged on an object holder 114. The object holder 114 is arranged on an object stage 122.

[0112] A settable or selectable aperture unit 306 is arranged above the second objective lens 304 (i.e. in the direction of the ion beam generator 301). Furthermore, provision is made for a guide system having a first guide device in the form of a first deflection device 307 and a second guide device in the form of a second deflection device 308. The first deflection device 307 is arranged source side, for example within the second objective lens 304. By contrast, the second deflection device 308 is arranged object side, for example within the second objective lens 304. The first deflection device 307 and the second deflection device 308 are crossed beam deflection devices. In other words, both the first deflection device 307 and the second deflection device 308 are embodied in such a way that the deflection devices 307, 308 deflect the ion beam in two directions which are not parallel to each other and are aligned at right angles to the direction of the optical axis in the form of the second beam axis 710 of the ion beam apparatus 300. For example, the first deflection device 307 and/or the second deflection device 308 is/are embodied as a magnetic deflection device(s). In particular, the first deflection device 307 and/or the second deflection device 308 accordingly each include/includes, for example, four air coils that are arranged around the optical axis in the form of the second beam axis 710 of the ion beam apparatus 300. In addition to that or in an alternative, provision is made for the first deflection device 307 and/or the second deflection device 308 to be embodied as electrostatic deflection device(s). In particular, the first deflection device 307 and/or the second deflection device 308 accordingly each include/includes, for example, four electrodes which are arranged around the optical axis in the form of the second beam axis 710 of the ion beam apparatus 300 and to which different electrostatic potentials can be applied. Using the first deflection device 307 and the second deflection device 308, the ion beam is deflected and can be scanned (or raster-scanned) over the object 125.

[0113] As explained above, the object holder 114 is arranged on the object stage 122. In the embodiment shown in FIG. 3, too, the object stage 122 is designed to be movable in three directions arranged perpendicular to one another, specifically in an x-direction (first stage axis), in a y-direction (second stage axis) and in a z-direction (third stage axis). Moreover, the object stage 122 can be rotated about two axes of rotation (axes of rotation of the stage) which are arranged perpendicular to one another.

[0114] The distances depicted in FIG. 3 between the individual units of the combination apparatus 200 are presented in exaggerated fashion in order to better illustrate the individual units of the combination apparatus 200.

[0115] A radiation detector 500 used to detect interaction radiation, for example x-ray radiation and/or cathodoluminescence, is arranged on the sample chamber 201. The radiation detector 500 is connected to a control device 123, which includes a monitor 124.

[0116] The control device 123 processes detection signals that are generated by the first detector 116 (not shown in FIG. 3), the second detector 117 (not shown in FIG. 3), the chamber detector 119, the third detector 121 and/or the radiation detector 500 and displays the detection signals in the form of images on the monitor 124.

[0117] The control device 123 also includes a database 126, in which data are stored and from which data are read out. Further, the control device 123 is connected to the guide system which includes the first deflection device 130 (not shown in FIG. 3) and the second deflection device 115 (not shown in FIG. 3) for the primary electron beam of the further SEM 100 and to the guide system which includes the first deflection device 307 and the second deflection device 308 for the ion beam of the ion beam apparatus 300.

[0118] The control device 123 of the combination apparatus 200 has a processor 127. A computer program product includes a program code which, when executed, carries out a method for operating the combination apparatus 200 is loaded in the processor 127. This is explained in detail further below.

[0119] It is also possible in the combination apparatus 200 to set working distances. It is possible in the further SEM 100, for example, to set a distance A1 using the control device 123. The distance A1 is given either (a) by an object distance between an outer boundary of the first objective lens 107 of the further SEM 100 and the object 125 or (b) by a focal plane distance between the outer boundary of the first objective lens 107 of the further SEM 100 and a focal plane of the first objective lens 107. The aforementioned distance A1 according to case (a) or case (b) is also referred to as working distance. For example, the distance A1 in case (a) is set by moving the object stage 122 and/or moving the first objective lens 107 using the movement device 25. For example, the distance A1 in case (b) is set by varying an excitation of the first objective lens 107 along the first beam axis 709 of the further SEM 100. It is further possible to set a distance A2 using the control device 123. The distance A2 is given either (a) by an object distance between an outer boundary of the second objective lens 304 of the ion beam apparatus 300 and the object 125 or (b) by a focal plane distance between the outer boundary of the second objective lens 304 of the ion beam apparatus 300 and a focal plane of the second objective lens 304. The aforementioned distance A2 according to case (a) or case (b) is also referred to as working distance. For example, the distance A2 in case (a) is set by moving the object stage 122 and/or moving the second objective lens 304 using a movement device 25. For example, the distance A2 in case (b) is set by varying an excitation of the second objective lens 304 along the second beam axis 710 of the ion beam apparatus 300.

[0120] Hereinbelow, the object stage 122 of the further SEM 100 as shown in FIG. 2, the yet further SEM 100 as shown in FIG. 2A and the combination apparatus 200 as shown in FIG. 3 are discussed in detail. The object stage 122 is designed as a movable object stage, which is depicted schematically in FIGS. 4 and 5. The same applies correspondingly to the object stage 19 of the SEM 100 as shown in FIG. 1.

[0121] Reference is made to the fact that the invention is not restricted to the object stage 122 described here. Rather, the invention can include any movable object stage suitable for the invention.

[0122] The object holder 114 is arranged on the object stage 122. The object stage 122 includes movement elements that ensure a movement of the object stage 122 in such a way that a region of interest on the object 125 can be examined, for example using a particle beam. The movement elements are depicted schematically in FIGS. 4 and 5 and are explained below.

[0123] The object stage 122 includes a first movement element 600 for example arranged on a housing 601 of the sample chamber 120 or 201, in which the object stage 122 is arranged in turn. The first movement element 600 enables a movement of the object stage 122 along the z-axis (third stage axis). A second movement element 602 is also provided. The second movement element 602 enables a rotation of the object stage 122 about a first axis of rotation 603 of the stage, which is also referred to as a tilt axis. This second movement element 602 serves to tilt the object 125 about the first axis of rotation 603 of the stage, where the object 125 is arranged on the object holder 114.

[0124] In turn, a third movement element 604, which is designed as a guide for a slide and ensures that the object stage 122 is movable in the x-direction (first stage axis), is arranged on the second movement element 602. The aforementioned slide is in turn a further movement element, specifically a fourth movement element 605. The fourth movement element 605 is designed such that the object stage 122 is movable in the y-direction (second stage axis). For this purpose, the fourth movement element 605 includes a guide in which a further slide is guided, the object holder 114 in turn being arranged on the latter. The object holder 114 is in turn designed with a fifth movement element 606, which enables a rotation of the object holder 114 about a second axis of rotation 607 of the stage. The second axis of rotation 607 of the stage is oriented perpendicularly to the first axis of rotation 603 of the stage.

[0125] On account of the above-described arrangement, the object stage 122 of the embodiment discussed here has the following kinematic chain: first movement element 600 (movement along the z-axis)second movement element 602 (rotation about the first axis of rotation 603 of the stage)third movement element 604 (movement along the x-axis)fourth movement element 605 (movement along the y-axis)fifth movement element 606 (rotation about the second axis of rotation 607 of the stage).

[0126] In a further embodiment (not shown), provision is made for further movement elements to be arranged on the object stage 122 such that movements along further translational axes and/or about further rotation axes are made possible.

[0127] As is evident from FIG. 5, each of the aforementioned movement elements is connected to a drive unit in the form of a motor M1 to M5. In this regard, the first movement element 600 is connected to a first drive unit M1 and is driven owing to a driving force that is provided by the first drive unit M1. The second movement element 602 is connected to a second drive unit M2, which drives the second movement element 602. The third movement element 604 is connected in turn to a third drive unit M3. The third drive unit M3 provides a driving force for driving the third movement element 604. The fourth movement element 605 is connected to a fourth drive unit M4, with the fourth drive unit M4 driving the fourth movement element 605. Further, the fifth movement element 606 is connected to a fifth drive unit M5. The fifth drive unit M5 provides a driving force that drives the fifth movement element 606.

[0128] The aforementioned drive units M1 to M5 can be designed as stepper motors, for example, and are controlled by a drive control unit 608 and are each supplied with a supply current by the drive control unit 608 (cf. FIG. 5). Explicit reference is made to the fact that the invention is not restricted to the movement using stepper motors. Rather, any drive units suitable for the invention can be used as drive units, for example brushless motors.

[0129] Embodiments of the method according to the system described herein are explained in detail hereinbelow in relation to the SEM 100 as shown in FIG. 1. Corresponding statements apply in relation to the SEM 100 as shown in FIG. 2, the SEM 100 as shown in FIG. 2A and the combination apparatus 200 as shown in FIG. 3.

[0130] FIG. 6 shows one embodiment of the method according to the system described herein carried out by the SEM 100 as shown in FIG. 1. In method step S1, the particle beam in the form of the primary electron beam is generated using the beam generator 1.

[0131] Moreover, method step S2 provides for at least one value of a control parameter for controlling at least one functional unit of the SEM 100 to be selected using the control device 123. For example, the control parameter is a physical quantity, in particular a control current or a control voltage, but also for example a ratio of physical quantities, in particular an amplification of physical quantities. The values of the physical quantity for example can be set on or using the control device 123 and control and/or supply the functional unit of the SEM 100 in such a way that desired physical effects, for example the generation of specific magnetic fields and/or electrostatic fields, are achieved. Examples of the control parameter are explained further above. Reference is made to the above explanations for the control parameter examples, which also apply here.

[0132] In particular, in the embodiment of the method according to FIG. 6, a functional unit is understood to be a structural unit of the SEM 100 which can be set in any way. For example, the position of the functional unit in the SEM 100 can be set. In addition to that or in an alternative, provision is made for an electrostatic and/or magnetic embodiment of the functional unit to be set such that the guidance of the primary electron beam in the SEM 100 and/or the shape of the primary electron beam is deliberately influenced. The invention is not restricted to the aforementioned setting options. Rather, the functional unit can be set in any manner suitable for the invention. Furthermore, provision is for example made for the functional unit to be formed as a single functional unit or include a plurality of functional units. For example, the SEM 100 includes the following structural units, which can be used/are used as a functional unit in the method according to the system described herein: the beam generator 1, the extraction electrode 2, the control electrode 3, the anode 4, the first condenser lens 5, the second condenser lens 6 (if present), the aperture unit 7, the first deflection device 9, the objective lens 10, the second deflection device 12 and/or the object stage 19.

[0133] In the method according to the system as shown in FIG. 6, provision is now made in method step S3 for the functional unit, a plurality of the functional units or all functional units to be controlled with the value of the control parameter using the control device 123. This control causes the primary electron beam to be guided along a first beam path of the SEM 100 from the beam generator 1 in the direction of the object 15. Actuating the functional unit, the plurality of functional units or all functional units with the value of the control parameter in essence sets a first mode of operation of the SEM 100. In this first mode of operation of the SEM 100, the primary electron beam runs along the first beam path.

[0134] The primary electron beam is now guided to a predeterminable location of a scanning region on the surface of the object 15 in method step S4 using the first deflection device 9 and the second deflection device 12. In particular, provision is made for the first deflection device 9 to guide the primary electron beam away from the optical axis 20 at a first angle .sub.1 with respect to the optical axis 20. Furthermore, provision is made for the second deflection device 12 to guide the primary electron beam in the direction of the optical axis 20 at a second angle 1 with respect to the optical axis 20 (cf. FIG. 1). When guiding the primary electron beam to the predeterminable location at the predeterminable position VP, the first angle .sub.1 runs through a first predeterminable value range and the second angle .sub.1 runs through a second predeterminable value range, while the primary electron beam remains at the predeterminable location. In other words, the method known as rocking beam is performed at the predeterminable location.

[0135] For example, in a further embodiment of the method according to the system described herein, the first angle .sub.1 is used as the second angle .sub.1. In other words, the first angle .sub.1 and the second angle .sub.1 are identical. Accordingly, when controlling the functional unit, the plurality of functional units or all functional units with the value of the control parameter, the primary electron beam (i) is guided away from the optical axis 20 at the first angle .sub.1 to the optical axis 20 by the first deflection device 9, and (ii) is subsequently guided back in the direction of the optical axis 20 at the first angle .sub.1 to the optical axis 20 by the second deflection device 12. For example, a value range with angles from the range between 0 and 90 is used as the first predeterminable value range. Furthermore, a value range with angles from the range between 0 and 90, for example, is used as the second predeterminable value range. Explicit reference is made to the fact that the invention is not restricted to the aforementioned angles. Rather, any angle suitable for the invention can be used. A further embodiment of the method according to the system described herein provides for the first predeterminable value range to be used as the second predeterminable value range. In other words, for example, the first predeterminable value range and the second predeterminable value range are identical.

[0136] In a method step S5 of the method according to the system described herein, provision is made for first interaction particles and/or a first interaction radiation to be detected using the first detector unit 14 and/or the second detector unit 8. For example, secondary particles, in particular secondary electrons or secondary ions, and/or backscatter particles, in particular electrons backscattered from the object 15 (backscattered electrons), are detected using the first detector unit 14 and/or the second detector unit 8. For example, x-ray radiation and/or cathodoluminescence is detected as first interaction radiation. The first interaction particles and/or the first interaction radiation result/results from an interaction of the primary electron beam with the object 15 when the primary electron beam is incident on the object 15. First detection signals are generated using the detected first interaction particles and/or the detected first interaction radiation. Further, a first image of the object 15 is generated using the first detection signals using the control device 123.

[0137] Method step S6 provides for at least one value of a further control parameter for controlling at least one functional unit of the SEM 100 to be selected using the control device 123. For example, the further control parameter is also a physical quantity, in particular a control current or a control voltage, but also for example the ratio of physical quantities, in particular an amplification of physical quantities. The values of the physical quantity for example can be set on or using the control device 123 and control and/or supply the functional unit of the SEM 100 in such a way that desired physical effects, for example the generation of specific magnetic fields and/or electrostatic fields, are achieved. Examples of the control parameter are explained further above. Reference is made to the above explanations for the control parameter examples, which also apply here. One embodiment of the method according to the system described herein provides for the control parameter and the further control parameter to be identical. Hence, the value of the control parameter is a first value and the value of the further control parameter is a second value.

[0138] The functional unit to be controlled by the further control parameter is also understood to be a structural unit of the SEM 100 which can be set in any way. For example, the position of the functional unit in the SEM 100 can be set. In addition to that or in an alternative, provision is made for an electrostatic and/or magnetic embodiment of the functional unit to be set such that the guidance of the primary electron beam in the SEM 100 and/or the shape of the primary electron beam is deliberately influenced. The invention is not restricted to the aforementioned setting options. Rather, the functional unit can be set in any manner suitable for the invention. Furthermore, provision is for example made for the functional unit to be formed as a single functional unit or include a plurality of functional units. In particular, provision is made for the functional unit to be controlled with the control parameter and the functional unit to be controlled with the further control parameter to be identical or different. For example, for the method according to the system described herein, the following structural units of the SEM 100 can be used as a functional unit to be controlled with the further control parameter or are used as functional units: the beam generator 1, the extraction electrode 2, the control electrode 3, the anode 4, the first condenser lens 5, the second condenser lens 6 (if present), the aperture unit 7, the first deflection device 9, the objective lens 10, the second deflection device 12 and/or the object stage 19.

[0139] In method step S7, provision is made for one of the aforementioned functional units, a plurality of the functional units or all functional units to be controlled with the value of the further control parameter using the control device 123. This control causes the primary electron beam to be guided along a second beam path of the SEM 100 from the beam generator 1 in the direction of the object 15. Actuating the functional unit, the plurality of functional units or all functional units with the value of the further control parameter in essence sets a second mode of operation of the SEM 100. In the second mode of operation of the SEM 100, the primary electron beam runs along the second beam path.

[0140] The primary electron beam is now guided to the predeterminable location of a scanning region on the surface of the object 15 in method step S8 using the first deflection device 9 and the second deflection device 12. In particular, provision is made for the first deflection device 9 to guide the primary electron beam away from the optical axis 20 at a third angle .sub.2 with respect to the optical axis 20. Furthermore, provision is made for the second deflection device 12 to guide the primary electron beam in the direction of the optical axis 20 at a fourth angle .sub.2 with respect to the optical axis 20. When guiding the primary electron beam to the predeterminable location, the third angle .sub.2 runs through a third predeterminable value range and the fourth angle .sub.2 runs through a fourth predeterminable value range, while the primary electron beam remains at the predeterminable location at the predeterminable position VP (cf. FIG. 1). In other words, the method known as rocking beam is performed at the predeterminable location. For example, in a further embodiment of the method according to the system described herein, the third angle .sub.2 is used as the fourth angle .sub.2. In other words, the third angle .sub.2 and the fourth angle .sub.2 are identical. Accordingly, when controlling the functional unit, the plurality of functional units or all functional units with the value of the further control parameter, the primary electron beam (i) is guided away from the optical axis 20 at the third angle .sub.2 to the optical axis 20 by the first deflection device 9, and (ii) is subsequently guided back in the direction of the optical axis 20 at the third angle .sub.2 to the optical axis 20 by the second deflection device 12. For example, a value range with angles from the range between 0 and 90 is used as the third predeterminable value range. Furthermore, a value range with angles from the range between 0 and 90, for example, is used as the fourth predeterminable value range. Explicit reference is made to the fact that the invention is not restricted to the aforementioned angles. Rather, any angle suitable for the invention can be used. A further embodiment of the method according to the system described herein provides for the third predeterminable value range to be used as the fourth predeterminable value range. In other words, for example, the third predeterminable value range and the fourth predeterminable value range are identical.

[0141] In a method step S9 of the method according to the system described herein, provision is made for second interaction particles and/or a second interaction radiation to be detected using the first detector unit 14 and/or the second detector unit 8. For example, secondary particles, in particular secondary electrons or secondary ions, and/or backscatter particles, in particular electrons backscattered from the object 15 (backscattered electrons), are detected using the first detector unit 14 and/or the second detector unit 8. For example, x-ray radiation and/or cathodoluminescence is detected as second interaction radiation. The second interaction particles and/or the second interaction radiation result/results from an interaction of the primary electron beam with the object 15 when the primary electron beam is incident on the object 15. Second detection signals are generated using the detected second interaction particles and/or the detected second interaction radiation. Further, a second image of the object 15 is generated using the second detection signals using the control device 123.

[0142] In a method step S10, the control device 123 is now used to set a size, a shape and/or a position of an opening of the aperture unit 7 of the SEM 100. For example, the method step S10 sets the beam current of the primary electron beam and/or a convergence angle of the primary electron beam to the optical axis 20. In addition to that or in an alternative, provision is made for at least one electrostatic and/or magnetic deflection unit of the SEM 100 to be set. The deflection unit is for example embodied as the first deflection device 9 and/or as the second deflection device 12. However, the invention is not restricted to the aforementioned deflection unit. Rather, any electrostatic and/or magnetic deflection unit of the SEM 100 suitable for deflecting the primary electron beam can be used as a deflection unit. When setting the aperture unit 7 and/or the deflection unit, the scanning region is displaced in such a way that a first irradiation direction of the particle beam in the form of the primary electron beam in the direction of the predeterminable position VP on the surface of the object 15 corresponds to a second irradiation direction of the particle beam in the form of the primary electron beam in the direction of the predeterminable position VP on the surface of the object 15, where the first irradiation direction is ascertained from the first image and where the second irradiation direction is ascertained from the second image. In the embodiment as shown FIG. 2A, for example, the first deflection unit 131 and/or the second deflection unit 132 are/is adjusted until the first irradiation direction corresponds to the second irradiation direction. For example, the first image is compared with the second image in order to ascertain the first irradiation direction and the second irradiation direction, where, for example, the first image and the second image are superimposed. For example, Kikuchi lines recognizable in the two images are brought into alignment with one another. In addition to that or in an alternative, provision is made for the use of a Hough transform to align lines ascertained in both images. In addition to that or in an alternative, provision is made for deviations of the first image and the second image to be determined using an image recognition system. The aforementioned setting, for example the superimposition of the first image and the second image, is implemented until the deviations are no longer present or present only to a small extent. Then the first irradiation direction corresponds to the second irradiation direction.

[0143] Method step S10 is explained in greater detail with reference to FIGS. 7 and 8. In the embodiment as shown in FIG. 7, the size, the shape and/or the position of the opening of the aperture unit 7 of the SEM 100 is/are set in such a way that the first irradiation direction corresponds to the second irradiation direction. Then, the first beam path SV1 shown in FIG. 7, along which the primary electron beam PE1 runs in the first mode of operation of the SEM 100, and the second beam path SV2 shown in FIG. 7, along which the primary electron beam PE2 runs in the second mode of operation of the SEM 100, are incident on the surface of the object 15 at the same position, specifically the predeterminable position VP.

[0144] In the embodiment as shown in FIG. 8, the first deflection device 9 and the second deflection device 12 are used as the electrostatic and/or magnetic deflection unit. When this deflection unit of the SEM 100 is set, the scanning region is shifted in such a way that the first irradiation direction corresponds to the second irradiation direction. Then the first beam path SV1, along which the primary electron beam PE1 runs in the first mode of operation of the SEM 100, and the second beam path SV2, along which the primary electron beam PE2 runs in the second mode of operation of the SEM 100, are aligned with each other. Both the primary electron beam PE1 in the first mode of operation of the SEM 100 and the second primary electron beam PE2 in the second mode of operation of the SEM 100 are incident on the surface of the object 15 at the same position corresponding to the predeterminable position VP.

[0145] The system described herein recognizes that application of the method, referred to as rocking beam, in different modes of operation of the SEM 100 allows the different beam paths SV1 and SV2 caused by the different modes of operation of the SEM 100 to be aligned with each other or be mergeable. The system described herein ensures that, in the different modes of operation, the primary electron beam PE1 and PE2 firstly is guided to the same location (specifically the predeterminable position VP) on the object 15 and secondly has the same orientation with respect to the object 15, so that the same lattice plane of a crystal lattice of the object 15 is measured in a crystalline object 15.

[0146] All the embodiments of the method according to the invention described herein are not restricted to the mentioned sequence of the method steps. The invention also includes different sequences of the method steps which are suitable for solving the problem within the meaning of the invention. In an alternative to that or in addition, the method according to the invention also provides for the parallel implementation of at least two method steps. Furthermore, the embodiments of the method according to the invention described herein are not restricted to the complete scope of all the method steps mentioned above or further below. In particular, provision is made for individual or a plurality of the method steps described herein to be omitted in further embodiments.

[0147] The features of the invention that are disclosed in the present description, in the drawings and in the claims may be essential for the implementation of the invention in its various embodiments both individually and in any desired combinations. The invention is not restricted to the described embodiments. The invention can be varied within the scope of the claims and taking into account the knowledge of those skilled in the relevant art.