Particle beam device, method of operating a particle beam device, and computer program product

Abstract

The invention relates to a particle beam device (1) having a particle source (11), an extraction aperture (13), an anode aperture (14) and a beam tube (23). A driver system of the particle beam device (1) is configured to apply an extraction aperture potential (φExt) to the extraction aperture (13), an anode aperture potential (φA) to the anode aperture (14) which can be variably set, and a beam tube potential (φL) to the beam tube (23). A controller of the particle beam device (1) is configured to control the driver system such that a voltage between the extraction aperture (13) and the anode aperture (14) can be variably set, and thus an intensity of a current of the particle beam (3) passing through an aperture (14') of the anode aperture (14) can be variably set.

Description

Technical Field

[0001] This invention relates to a particle beam apparatus, specifically an apparatus for generating a beam of charged particles (particle beam), a method for operating the particle beam apparatus, and a computer program product enabling a computer to execute the method. In particular, the charged particles in the particle beam are electrons or ions. For example, the particle beam apparatus is a microscope, particularly a scanning electron microscope. Specifically, the invention relates to maximizing the current intensity of the particle beam that can be supplied to a sample. Background Technology

[0002] In such particle beam devices, it is necessary to be able to set the current intensity of the particle beam to a high value. Besides the maximum possible current intensity of the particle beam that can be guided onto the sample, the dynamic range of the particle beam current intensity is also a key performance characteristic. Dynamic range represents the range of values ​​that the particle beam current intensity can vary, and the number of setting options within that range. Some applications of particle beam devices require high current intensities; others require low current intensities. Therefore, a high dynamic range of the particle beam current intensity is necessary. Summary of the Invention

[0003] Therefore, the objective of this invention is to provide a particle beam device and a method for operating the particle beam device, which is suitable for generating particle beams with high maximum current intensity and high particle beam current intensity dynamic range.

[0004] This objective is achieved by means of a particle beam apparatus and a method for controlling the particle beam apparatus, as described below. Favorable developments in these subjects are also defined below.

[0005] A first aspect of the invention relates to a particle beam apparatus, comprising: a particle source for providing charged particles; an extraction aperture having an aperture size; and a driving system configured to apply an extraction aperture potential to the extraction aperture. Thus, these charged particles form a particle beam that passes through the aperture of the extraction aperture; an anode aperture, disposed downstream of the extraction aperture and having an aperture, onto which the particle beam is guided during operation; wherein, the actuator system is further configured to apply a potential to the anode aperture that can be set in a variable manner and is different from that of the extraction aperture. Anode aperture potential A beam tube, disposed downstream of the anode aperture and having an inlet aperture, through which the particle beam enters the beam tube during operation; wherein the actuator system is further configured to apply a potential to the beam tube different from that of the anode aperture. tube potential A controller configured to control the driver system such that the voltage between the extraction aperture and the anode aperture can be set in a variable manner; wherein the aperture of the extraction aperture and the aperture of the anode aperture are matched to each other such that the current intensity of the particle beam passing through the aperture of the anode aperture can be set in a variable manner by changing the voltage between the extraction aperture and the anode aperture.

[0006] For example, the particle source is a cathode that provides bound electrons. An extraction aperture is used, for example, to separate electrons bound in the cathode during field emission and thus generate free electrons. For this purpose, an extraction aperture potential is applied to the extraction aperture. The extraction aperture potential is different from the particle source potential applied to the particle source (cathode). Therefore, a sufficiently strong electric field is generated between the cathode and the extraction aperture to separate the electrons bound in the cathode. The setting of the extraction aperture potential is further explained below. A specific example. A particle beam (electron beam) is formed from free electrons.

[0007] However, a particle source can also be an ion source that provides ions.

[0008] An extraction aperture has an opening called an aperture. The aperture is defined and delimited by the extraction aperture. For example, the extraction aperture can be a metal plate. During operation, charged particles pass through the aperture of the extraction aperture, thus forming a particle beam.

[0009] In this specification, "the first object is arranged upstream of the second object" and "the second object is arranged downstream of the first object" each mean that the first object is arranged in front of the second object along the propagation direction of the particle beam. Accordingly, the particle beam first reaches the position of the first object and then reaches the position of the second object. The term "upstream" can also mean "opposite to the propagation direction of the particle beam." The term "downstream" can also mean "along the propagation direction of the particle beam."

[0010] The anode aperture is positioned downstream of the extraction aperture. This means that particles supplied by the particle source first pass through the extraction aperture and then impact the anode aperture or pass through its aperture. Particles in a particle beam impacting the anode aperture itself are blocked by the anode aperture and cannot pass through it. Particles in a particle beam guided to the aperture of the anode aperture are blocked by the anode aperture and can pass through it.

[0011] The actuator system allows for the application of different potentials, which can be set in a variable manner, to the extraction aperture and the anode aperture. This enables the generation of a variable electric field between the extraction aperture and the anode aperture that acts on the particle beam. The electric field (e.g., due to the geometry of the extraction aperture and the anode aperture, where they are oriented substantially parallel to each other) acts, for example, substantially parallel to the central axis of the particle beam apparatus. The direction and intensity of the electric field can be set in a variable manner according to the voltage between the extraction aperture and the anode aperture, which is determined by the extraction aperture potential. and anode aperture potential It can be defined and set in a variable manner by the controller through the control drive system. This means that the strength of the electric field can be set to a large number of different values ​​in a targeted manner by control signals from the controller.

[0012] Therefore, the voltage between the extraction aperture and the anode aperture (i.e., the extraction aperture potential) can be used to determine the voltage between the extraction aperture and the anode aperture. With the potential of the anode aperture The voltage between particles accelerates or brakes the particles in the particle beam; specifically, each particle is accelerated and braked to varying degrees.

[0013] Due to the acceleration or braking of the particles in the particle beam between the extraction aperture and the anode aperture, the divergence angle of the particle beam also changes. Therefore, the position-dependent number of particles passing through the aperture of the anode aperture per unit time and per unit area (i.e., the local current intensity within the aperture of the anode aperture) also changes. Consequently, the current intensity capable of passing through the aperture of the anode aperture, and therefore the maximum current intensity that can be guided onto the sample, can be set via the voltage between the extraction aperture and the anode aperture.

[0014] According to one embodiment, for this purpose, the aperture of the extraction aperture and the aperture of the anode aperture are matched to each other, such that the ratio of particles of the particle beam passing through the aperture of the anode aperture to particles of the particle beam blocked by the anode aperture can be variably set by changing the voltage between the extraction aperture and the anode aperture. This ratio is defined by a dividend and a divisor. The dividend represents the portion of the particle beam whose particles are not blocked by the anode aperture and pass through the aperture of the anode aperture. The divisor represents the portion of the particle beam whose particles are blocked by the anode aperture and do not pass through the aperture of the anode aperture. Accordingly, the anode aperture limits the current intensity of the particle beam passing through the anode aperture and through its aperture by blocking a portion of the particle beam (which can be variably set).

[0015] By way of example, the controller includes an operating mode in which the control driver system (i.e., the controller controls the driver system) causes the voltage between the extraction aperture and the anode aperture to have a first voltage value (i.e., the controller can be operated in such an operating mode). The current intensity of the particle beam passing through the anode aperture and through the aperture of the anode aperture is correspondingly limited to the first value.

[0016] By way of example, the controller includes an operating mode in which the control driver system causes the voltage between the extraction aperture and the anode aperture to have a second voltage value different from the first voltage value (i.e., the controller can be operated in such an operating mode). The current intensity of the particle beam passing through the anode aperture and through the aperture of the anode aperture is correspondingly limited to the second value different from the first value.

[0017] According to one embodiment, the controller is configured to control the driver system such that the absolute value of the voltage between the orifice and the anode orifice is extracted (i.e., It is at least 1kV.

[0018] When the controller sets the same potential at the extraction aperture and the anode aperture by controlling the driver system, no electric field (or an electric field with zero field strength) is generated between the extraction aperture and the anode aperture. Accordingly, the charged particles of the particle beam are not further accelerated or braked.

[0019] The extraction orifice and the anode orifice are specifically arranged to be directly adjacent along the central axis. Other orifices, to which a potential can be applied in a targeted and controlled manner, are correspondingly not arranged between the extraction orifice and the anode orifice.

[0020] The actuator system allows for the application of varying potentials to the anode aperture and the beam tube. This enables the generation of an electric field between the anode aperture and the beam tube that acts on the particle beam. This electric field (e.g., due to the geometry of the anode aperture and the beam tube) acts substantially parallel to the central axis of the particle beam apparatus. The direction and intensity of the electric field can be varied according to the voltage between the anode aperture and the beam tube, which is determined by the anode aperture potential. and bundle potential It can be defined and set in a variable manner by the controller through the control drive system. This means that the strength of the electric field can be set to a large number of different values ​​in a targeted manner by control signals from the controller.

[0021] According to one embodiment, the driver system is also configured to variably set the bundle tube potential. This provides further degrees of freedom for controlling the particle beam, and the electric field between the anode aperture and the beam tube can be changed by altering the beam tube potential. To change.

[0022] According to one embodiment, the controller is configured to generate an anode aperture potential by controlling the driver system. and bundle potential This causes the particles in the particle beam to be braked between the anode aperture and the beam tube.

[0023] According to one embodiment, the controller is configured to generate an anode aperture potential by controlling the driver system. and bundle potential This causes the particles in the particle beam to be accelerated between the anode aperture and the beam tube.

[0024] According to one embodiment, the extraction aperture, the anode aperture, and the bundle tube are each electrically isolated from each other, so that different potentials can be applied to the extraction aperture, the anode aperture, and the bundle tube.

[0025] According to one embodiment, the controller is configured to control the driver system such that the absolute value of the voltage between the anode aperture and the bundle tube (i.e., It is at least 1kV.

[0026] The anode aperture and the bundle tube are specifically arranged to be directly adjacent to each other along the central axis. Other apertures, which can be applied with a potential that can be controlled in a targeted manner, are correspondingly not arranged between the anode aperture and the bundle tube.

[0027] According to one embodiment, the distance between the extraction aperture and the anode aperture is not zero and is less than 4 mm. In one configuration, for example, the distance is 2 mm. Alternatively, the distance can be greater than 4 mm, for example, 7 mm.

[0028] According to one embodiment, the distance between the aperture of the extraction aperture and the inlet aperture of the beam tube is at least 5 mm and / or at most 20 mm, preferably at most 14 mm, and more preferably at most 10 mm. This means that the structure of the extraction aperture, anode aperture, and inlet aperture of the beam tube can be implemented using a relatively small installation space. Thus, the invention can be easily implemented within a pre-existing structure. Therefore, another structure of the particle beam device does not need to be significantly adapted relative to existing structures.

[0029] According to one embodiment, the particle beam apparatus further includes a termination aperture arranged downstream of the beam tube and having an aperture through which the particle beam passes during operation; wherein the actuator system is further configured to apply a termination aperture potential to the termination aperture. The driver system is configured to generate the bundle tube potential. and termination aperture potential This allows the voltage between the beam tube and the termination aperture to be set to different values ​​based on signals from the controller. This enables the setting of the energy of the particles in the particle beam before they impact the sample (i.e., the landing energy).

[0030] The termination aperture can be specifically electrically isolated from the beam tube. The termination aperture can be the last component of the particle beam apparatus along the central axis before the particle beam impacts the sample. Therefore, the termination aperture can be the last aperture through which the particle beam passes before it impacts the sample.

[0031] According to one embodiment, the controller is configured to generate a bundle tube potential by controlling the driver system. and termination aperture potential This causes the particles in the particle beam to be braked between the beam tube and the termination aperture.

[0032] According to one embodiment, the particle beam apparatus further includes: a sample holder capable of positioning a sample on the sample holder; wherein the actuator system is further configured to apply a sample potential to the sample or the sample holder; wherein the actuator system is configured to generate a termination aperture potential. and sample potential This allows the voltage between the termination aperture and the sample, or between the termination aperture and the sample holder, to be set to different values ​​based on signals from the controller. This enables the setting of the energy (i.e., landing energy) of the particles in the particle beam before they impact the sample.

[0033] According to one embodiment, the actuator system is also configured to apply a particle source potential to the particle source.

[0034] The following provides several specific examples of the potential and voltage ranges for the various components of a particle beam apparatus, within which the potentials and voltages can be set.

[0035] Particle source potential applied to the particle source It can be set relative to ground (0V) in the range of -30kV to -100V.

[0036] Extraction aperture potential (i.e., the voltage between the aperture and the particle source) With particle source potential The difference between It can be set within the range of 0.5kV to 7kV. Accordingly, the situation is as follows: That is, extract the aperture potential. Can be set from arrive Within the range.

[0037] Anode aperture potential applied to the anode aperture It can be set relative to ground (0V) in the range of -15kV to +15kV.

[0038] Bundle tube potential applied to the bundle tube It can be set relative to ground (0V) in the range of 0kV to 10kV.

[0039] Termination aperture potential applied to the termination aperture It can be set relative to ground (0V) in a range from -1kV to +1kV, particularly in a range from -5kV to +5kV. For example, the bundled tube potential. With the termination aperture potential The difference between them is set to a value in the range from 0kV to 10kV, and in particular from 0kV to 15kV.

[0040] Sample potential applied to the sample or sample holder It can be set relative to ground (0V) in a range from -1kV to +1kV, particularly in a range from -5kV to +5kV. For example, the termination aperture potential. With sample potential The difference between them is set to a value in the range from 0kV to +5kV, and in particular from -5kV to +5kV.

[0041] The above values ​​are particularly applicable to cases where the distance between the extraction aperture and the anode aperture is relatively large (e.g., greater than 4 mm, especially about 7 mm).

[0042] When the distance between the extraction aperture and the anode aperture is small (e.g., less than 4 mm, especially about 2 mm), unlike the configuration described above, it is possible to extract from... arrive Especially from arrive Operating anode aperture potential within the range

[0043] According to one embodiment, the controller is also configured to change the voltage between the extraction aperture and the anode aperture and, in the process, to change the potential of the extraction aperture. With particle source potential The voltage between the extraction aperture and the anode aperture is kept substantially constant so that the electric field strength at the emission peak of the particle source remains substantially constant. To ensure that the electric field strength at the emission peak of the particle source remains as constant as possible immediately after a change in the voltage between the extraction aperture and the anode aperture, a slight change in the extraction aperture potential can also be specified. With particle source potential The voltage between them. In this case, extract the aperture potential. With particle source potential The voltage change between them is much smaller than the voltage change between the extraction aperture and the anode aperture. The extraction aperture potential is illustrated by the example. With particle source potential The voltage change between them is at least 50 (preferably at least 200) times smaller than the voltage change between the extraction aperture and the anode aperture.

[0044] According to one embodiment, the controller is also configured to change the voltage between the extraction aperture and the anode aperture and, in the process, keep the voltage between the particle source and the sample or between the particle source and the sample holder constant.

[0045] The potential and voltage values ​​mentioned in this article refer to particle beams containing negatively charged particles (electrons). In the case of particle beams including positively charged particles (ions), these values ​​apply with opposite polarity.

[0046] This document specifies the range of potential indications, allowing the setting of a corresponding potential range. In other words, the drive system is configured to generate a defined potential covering the corresponding range, and the controller is configured to instruct the drive system to generate the corresponding potential.

[0047] According to one embodiment, the particle beam apparatus further includes: a multi-aperture aperture arranged in a beam tube downstream of the inlet aperture of the beam tube and having a plurality of adjacent apertures of different sizes; and a deflection system configured to selectively deflect the particle beam onto one of the apertures of the multi-aperture aperture. A controller is configured to drive the deflection system to deflect the particle beam.

[0048] According to one embodiment, the multi-aperture orifice gate is a pressure-stage orifice gate, through which a vacuum region upstream of the multi-aperture orifice gate and a vacuum region downstream of the multi-aperture orifice gate are separated from each other. The two vacuum regions maintain different vacuums and are spatially separated from each other by the pressure-stage orifice gate. In this case, the vacuum region upstream of the multi-aperture orifice gate is the ultra-high vacuum region of the beam generator.

[0049] According to one embodiment, the particle beam apparatus has a first vacuum region in which a particle source and an extraction aperture are arranged, and a second vacuum region in which an inlet aperture of a beam tube is arranged. During operation, the first and second vacuum regions maintain different vacuum levels.

[0050] According to one embodiment, the anode orifice is disposed at the interface between the first vacuum region and the second vacuum region. The anode orifice serves here as a pressure stage orifice. Different vacuum levels generate pressures that affect the pressure stage orifice. However, the pressure stage orifice is designed to withstand pressure.

[0051] According to one embodiment, the particle beam apparatus further includes an objective lens disposed downstream of the inlet aperture of the beam tube (and downstream of the multi-aperture aperture) and configured to focus the focusing particle beam (onto the sample).

[0052] A second aspect of the invention relates to a method for controlling a particle beam apparatus. The method includes controlling the voltage between an extraction aperture and an anode aperture, thereby altering the current intensity of the particle beam passing through the aperture of the anode aperture. This change is not arbitrary but controlled. By way of example, the controlled change is implemented via a program executed by a processor of a controller. This program can indicate the change via operating parameters read and processed by the controller, i.e., the controller controls the actuator system based on operating parameters representing the voltage change between the extraction aperture and the anode aperture.

[0053] A third aspect of the invention relates to a computer program product comprising computer-readable instructions that, when executed on a computer, cause the computer to perform one of the methods described herein. For example, the computer program product may be a data carrier on which computer-readable instructions are recorded. However, the computer program product may also be a signal stored in a data storage device and capable of being transmitted from one computer to another via data communication. Attached Figure Description

[0054] Embodiments of the present invention will now be explained in more detail with reference to the accompanying drawings, in which:

[0055] Figure 1 A schematic diagram of a particle beam device is shown;

[0056] Figure 2 A schematic diagram showing the various components of a particle beam apparatus and the potentials applied to these components;

[0057] Figure 3A A schematic illustration of a portion of the particle beam device in a first operating mode is shown;

[0058] Figure 3B A schematic diagram of this portion of the particle beam device in a second operating mode is shown; and

[0059] Figure 3C A schematic diagram of this part of the particle beam device in the third operating mode is shown. Detailed Implementation

[0060] Figure 1 A schematic illustration of a particle beam apparatus 1 is shown. In the example shown, particle beam apparatus 1 is a scanning electron microscope. However, particle beam apparatus 1 can also be an ion beam column, such as a focused ion beam system (FIB system). Particle beam apparatus 1 can be part of a particle beam system that may include multiple such particle beam apparatuses having a common working area.

[0061] The particle beam device 1 includes a particle source 11 configured to provide charged particles. An electric potential, referred to herein as the particle source potential, can be applied to the particle source. (see Figure 2 ).

[0062] The particle beam apparatus 1 also includes a suppression electrode 12 configured to prevent particles thermally emitted by the particle source 11 from moving downstream (i.e., in the direction of the sample 4) along the central axis 2. The suppression electrode 12 specifically blocks particles emitted at a much higher level than the emission peak of the particle source 11. This is achieved by applying a potential different from that of the particle source to the suppression electrode 12 in a specific manner. electric potential An electric field is generated between the particle source 11 and the suppression electrode 12, which largely prevents particles emitted by the particle source 11 upstream of the suppression electrode 12 from affecting the particle beam 3, as will be described later. The strength of the electric field can be set such that only thermally emitted particles are blocked.

[0063] The particle beam apparatus 1 also includes an extraction aperture 13 disposed downstream of the particle source 11. A potential, referred to herein as the extraction aperture potential, can be applied to the extraction aperture 13. (see Figure 2 ). Generate extraction aperture potential and particle source potential This makes the extraction aperture potential With particle source potential The resulting voltage generates an electric field between the particle source 11 and the extraction aperture 13, which extracts charged particles from the particle source 11 (this is called field emission).

[0064] Extraction aperture 13 has an aperture diameter of 13' (see Figure 2 Charged particles extracted from particle source 11 pass through the aperture. These particles form a particle beam 3 downstream, manipulated by another component of particle beam device 1.

[0065] An anode aperture 14 with an aperture diameter of 14' is arranged downstream of the extraction aperture 13 (see [reference]). Figure 2 During operation, the particle beam 3 is guided onto the aperture 14' of the anode aperture 14. A potential can be applied to the anode aperture 14; this potential is referred to herein as the anode aperture potential. (see Figure 2 Anode aperture potential With extraction aperture potential The resulting voltage generates an electric field between the extraction aperture 13 and the anode aperture 14. This electric field, depending on its direction and intensity, can accelerate or brake the particles of the particle beam 3, specifically accelerating and braking each particle to varying degrees. (See later reference...) Figures 3A to 3C Further details regarding the operation and use of the anode aperture 14 are described.

[0066] The particle source 11 and the extraction aperture 13 are arranged in a first vacuum zone V1, in which a first vacuum (ultra-high vacuum) is formed during operation. The first vacuum is established, for example, by a pump consisting of a first housing section 15, a second housing section 16, an anode aperture 14, and the evacuation zone V1 (not shown). The first housing section 15 is designed to be, for example, an electrical conductor, while the second housing section 16 is an electrical insulator.

[0067] The particle beam device 1 also includes a beam tube 23 disposed downstream of the anode aperture 14. Figure 1 In the example shown, viewed along the central axis 2 of the particle beam apparatus 1, the beam tube 23 extends approximately from the anode aperture 14 into the interior of the objective lens 30. The beam tube 23 comprises a tubular body having a hollow interior 24, the tubular body having an inlet aperture 23' on the anode aperture 14 side and an outlet aperture 23" on the opposite side (see [reference]). Figure 2 During operation, the particle beam 3 from the anode aperture 14 enters the interior 24 of the bundle tube 23 through the inlet aperture 23', passes through the interior 24 of the bundle tube 23, and exits the bundle tube 23 through the outlet aperture 23".

[0068] A potential can be applied to the bundle tube 23; this potential is referred to in this paper as the bundle tube potential. (see Figure 2 Anode aperture potential With bundle tube potential The resulting voltage generates an electric field between the anode aperture 14 and the bundle tube 23. This electric field can accelerate or brake the particles of the particle beam 3 depending on its direction and intensity, specifically, accelerating and braking each particle to different degrees.

[0069] During operation, the particle beam device 1 has a second vacuum region V2 within the beam tube 23, in which a second vacuum is formed that differs from the first vacuum in the first vacuum region V1. The inlet aperture 23' of the beam tube is located within the second vacuum region V2, which is... Figure 1 The example shown extends to objective lens 30. A second vacuum zone V2 is established, for example, by a beam tube 23, an anode aperture 14, and a pump for evacuating the vacuum zone V2 (not shown). The anode aperture 14 is located at the interface between the two vacuum zones V1 and V2 and serves as a pressure stage aperture. The particle beam 3 passes through the interface between the two vacuum zones V1 and V2.

[0070] exist Figure 2 In the diagram, the distance D between the aperture 13' of the extraction aperture 13 and the inlet aperture 23' of the bundle tube 23 is indicated by a double-headed arrow. Figure 2 In the diagram, the distance E between the extraction port 13 and the anode port 14 is indicated by a double-headed arrow. The extraction port 13 and the anode port 14 require relatively small installation space, meaning the distance D can be between 5 mm and 20 mm. For example, the distance D is at least 5 mm and / or at most 20 mm, preferably at most 14 mm, and more preferably at most 10 mm.

[0071] The particle beam device 1 also includes a multi-aperture aperture 40 disposed in the hollow interior 24 of the beam tube 23. Therefore, the multi-aperture aperture 40 is disposed downstream of the inlet aperture 23' of the beam tube 23 and upstream of the outlet aperture 23" of the beam tube 23.

[0072] The multi-aperture gate 40 has multiple apertures 41 of different sizes. The apertures 41 are spaced apart from each other so that they do not overlap. In the plane in which the multi-aperture gate 40 is arranged (perpendicular to the central axis 2), the size of the apertures 41 is within the range of the diameter of the particle beam 3. Therefore, the multi-aperture gate 40 is suitable for blocking a portion of the incident particle beam 3, thus limiting the current intensity of the particle beam 3. Depending on the size of the apertures 41, the current intensity of the particle beam 3 can be limited to varying degrees. This means that the apertures 41 are designed such that the current intensity of the particle beam 3 upstream of the multi-aperture gate 40 is greater than the current intensity of the particle beam 3 immediately following it through the multi-aperture gate 40.

[0073] However, the multi-aperture gate 40 may also have one or more apertures, which are large enough to keep the current intensity of the particle beam 3 constant. When the particle beam 3 passes through such an aperture, the current intensity of the particle beam 3 is effectively limited by another gate, such as the anode gate 14. In this case, the current intensity of the particle beam 3 does not decrease after passing through the multi-aperture gate 40.

[0074] like Figure 1 As shown, the anode aperture 14 and the multi-aperture aperture 40 can be oriented (substantially) parallel to each other, and each is oriented perpendicular to the central axis 2.

[0075] The particle beam apparatus 1 also includes a deflection system 43 configured to selectively deflect the particle beam 3 through one of the apertures 41 of the multi-aperture aperture 40, the particle beam having passed through the anode aperture 14 and entered the beam tube 23 through the inlet aperture 23'. Figure 1In the example shown, the deflection system 43 includes three deflection units 44, 45, and 46. Each of the deflection units 44 to 46 is configured to deflect the particle beam 3 in the radial direction (i.e., perpendicular to the central axis 2). Deflecting the particle beam 3 means changing the direction of the particle beam 3. Figure 1 In the example shown, deflection units 44 to 46 include coils. Deflection units 44 to 46 are synchronously controlled. The coils of deflection units 44 to 46 are arranged outside the bundle tube 23. Electrically operated deflection units can also replace magnetic deflection units in the form of coils.

[0076] The deflection unit 44 is configured to deflect the particle beam 3 between the inlet aperture 23' and the multi-aperture gate 40. The particle beam 3 can thus be selectively guided onto one of the apertures 41 of the multi-aperture gate 40 (precisely). When the particle beam 3 is guided onto one of the apertures 41 of the multi-aperture gate 40 and partially impacts the multi-aperture gate 40 itself in the process, the particle beam 3 is partially blocked by the multi-aperture gate 40, thus altering the current intensity of the particle beam 3. Therefore, the current intensity of the particle beam 3 can be set to different values ​​depending on the size of the aperture 41.

[0077] After passing through the multi-aperture stop 40, the particle beam 3 is deflected again by other deflection units 45 and 46 and thus guided onto the objective lens 30. The deflection units 45 and 46 are configured to deflect the particle beam 3 radially between the multi-aperture stop 40 and the objective lens 30.

[0078] The multi-aperture aperture 40 and the deflection system 43 enable the current intensity of the particle beam 3 to be set to different values. This produces a dynamic range of the current intensity of the particle beam 3.

[0079] The particle beam apparatus 1 also includes a focusing lens 51 configured to generate a magnetic field for focusing the particle beam 3 between the multi-aperture aperture 40 and the objective lens 30. The focusing lens 51 includes a magnetic core 52 for guiding the magnetic field and an excitation coil 53 for generating the magnetic field. The magnetic core 52 is designed to be substantially rotationally symmetric about the central axis 2. For example, the magnetic core 52 is an integral design. The magnetic core 52 is completely disposed outside the beam tube 23. The magnetic core 52 is disposed downstream of the anode aperture 14 along the central axis 2. The magnetic core 52 is designed such that the magnetic field generated by the first focusing lens 51 primarily functions within the effective region of the deflection unit 45.

[0080] The focusing lens 51 changes the divergence angle of the particle beam 3 by focusing it downstream of the multi-aperture stop 40 and upstream of the objective lens 30. The beam diameter of the particle beam 3 (measured perpendicular to the central axis 2) can thus be varied. Specifically, the beam diameter of the particle beam 3 can be adapted to the effective area of ​​the objective lens 30.

[0081] The particle beam apparatus 1 also includes an objective lens 30 disposed downstream of the multi-aperture aperture 40 and downstream of the effective region of the focusing lens 51. The objective lens 30 is configured to focus the particle beam 3 onto a sample 4 positioned on a sample holder 5. For this purpose, the objective lens 30 includes, for example, a magnetic core 31 and an excitation coil 32. The excitation coil 32 is configured to generate a magnetic field guided by the magnetic core 31. The magnetic field exits the magnetic core 31 in a gap 33 and is formed when properly excited, such that the magnetic field has a focusing effect on the particle beam 3. Figure 1 In the example shown, viewed along the central axis 2 of the particle beam device 1, the position of the gap 33 is approximately flush with the exit aperture 23" of the beam tube 23.

[0082] The deflection system 35 is arranged flush with the objective lens 30 along the central axis 2 and configured to deflect the particle beam 3 in the radial direction (i.e., perpendicular to the central axis 2), thereby facilitating the guidance of the particle beam 3 to different positions on the surface of the sample 4. Figure 1 In the example shown, the deflection system 35 includes two deflection units 36 and 37 formed by coils. Figure 1 In the example shown, the coils of deflection units 36 and 37 are arranged between the bundle tube 23 and the magnetic core 31 of the objective lens 30. The two deflection units 36 and 37 are arranged in a manner that distributes them along the central axis 2.

[0083] The particle beam device 1 also includes a beam tube 23 downstream of which an aperture 38' is provided (see below). Figure 2 The termination aperture 38 is through which the particle beam 3 passes during operation. A potential can be applied to the termination aperture 38; this potential is referred to herein as the termination aperture potential. (see Figure 2 ). Generate termination aperture potential. and bundle potential This makes the bundle tube potential With the termination aperture potential The voltage obtained between them (i.e., the bundle tube potential) With the termination aperture potential The difference between the two poles (28 and 23) generates an electric field that acts on the particle beam 3. This electric field (e.g., due to the geometry of the beam tube and the pole) acts substantially parallel to the central axis 2. The direction and intensity of the electric field can be set in a variable manner according to the voltage between the beam tube 23 and the pole 38, which is determined by the potential of the pole. and bundle potential Definition. This means that the strength of the electric field can be set to a large number of different values ​​in a targeted manner via control signals from the controller. For example, setting the voltage between the beam tube 23 and the termination aperture 38 causes the particles of the particle beam 3 to be braked. This allows the landing energy of the particles of the particle beam 3 on the sample 4 to be set.

[0084] exist Figure 1 In the example shown, the termination aperture 38 is formed by the magnetic core 31. However, this is merely an example. The termination aperture 38 can be separated from the magnetic core 31 and electrically isolated.

[0085] The particle beam apparatus 1 also includes a sample holder 5 capable of positioning the sample 4 thereon. A potential, referred to herein as the sample potential, can be applied to the sample holder 5 or the sample 4. (see Figure 2 ). Generate termination aperture potential. and sample potential This causes the termination aperture potential to be... With sample potential The resulting voltage between the termination aperture 38 and the sample 4 generates an electric field that acts on the particle beam 3. This electric field (e.g., due to the geometry of the termination aperture and the sample / sample holder) acts substantially parallel to the central axis 2. The direction and intensity of the electric field can be variably set according to the voltage between the termination aperture 38 and the sample 4 / sample holder 5, which is determined by the termination aperture potential. and sample potential Definition. This means that the strength of the electric field can be set to a large number of different values ​​in a targeted manner via control signals from the controller. For example, setting the voltage between the termination aperture 38 and the sample 4 / sample holder 5 causes the particles of the particle beam 3 to be braked. This allows the landing energy of the particles of the particle beam 3 on the sample 4 to be set.

[0086] The particle beam device 1 also includes a driver system 62. The driver system 62 is configured to generate the potential, voltage, and current required to operate the components of the particle beam device 1, and to supply these potentials, voltages, and currents to these components. The driver system 62 specifically generates the particle source potential. Extraction aperture potential Anode aperture potential Bundle tube potential Termination aperture potential and sample potential It also generates current for operating the focusing lens 51 and the objective lens 30.

[0087] For this purpose, the actuator system 62 may include one or more voltage and current sources that generate the potential, voltage, and current required to operate the components of the particle beam device 1. Line 63 represents all the electrical lines required to supply the potential, voltage, and current from the actuator system 62 to the various components of the particle beam device 1. Line 63 is shown schematically only.

[0088] The particle beam device 1 also includes a controller 61 for controlling the actuator system 62. The controller 61 can thus set the various potentials, voltages, and currents required to operate the components of the particle beam device 1 in a targeted manner, and therefore control the operation and action of the components of the particle beam device 1. The values ​​of the various potentials, voltages, and currents that need to be generated by the actuator system 62 can be represented in the controller 61 by corresponding operating parameters. For example, the operating parameters define the values ​​of potentials, voltages, or currents.

[0089] The controller 61 can change the operation and effect of the components of the particle beam device 1 by altering corresponding operating parameters. These operating parameters can be stored in the memory of the controller 61 and changed by the processor of the controller 61. A set of operating parameters sufficient to operate the particle beam device 1 defines the operating mode of the particle beam device 1. Multiple sets of operating parameters defining multiple different operating modes can be stored in the memory of the controller 61. Accordingly, the controller 61 can selectively operate the particle beam device 1 in one of multiple operating modes. For this purpose, the controller 61 loads the operating parameters of the selected operating mode from the memory and instructs the driver system 62 to generate the potential, voltage, and current required to operate the components of the particle beam device 1 according to the loaded operating parameters. The user can change the operating parameters of the operating mode using a user interface (e.g., keyboard, mouse, etc.). See below for further details. Figures 3A to 3C Various exemplary operating modes are described.

[0090] By way of example, particle beam device 1 is designed as Figure 1 The particle beam microscope is described. For this purpose, the particle beam apparatus 1 includes a detector 6. The detector 6 is designed as an aperture stop arranged inside the beam tube 23 upstream of the objective lens 30. A particle beam 3 from the particle source 11 passes through the aperture in the detector 6 and is focused onto the sample 4 by the objective lens 30. Due to the interaction between the particle beam 3 and the sample 4, the sample 4 emits particles. For example, the particles emitted by the sample 4 can be backscattered electrons or secondary electrons. When the particle beam apparatus 1 is an ion beam column, the particles emitted by the sample 4 can also be backscattered ions or secondary ions. Due to the interaction between the particle beam 3 and the sample 4, radiation (e.g., light in the form of fluorescence, cathodoluminescence, or X-ray radiation) can also be emitted and detected. Figure 1In the example, charged particles emitted by sample 4 enter the beam tube 23 through objective lens 30 and are detected by one of detectors 6 depending on their trajectory. Other types of detectors may also be used.

[0091] The following text is for reference only. Figures 3A to 3C The operation of the anode aperture 14 is described for different operating modes. Among the components of the particle beam system 1, Figure 3A Only the particle source 11, the suppression electrode 12, the extraction aperture 13, and the anode aperture 14, as well as the potential applied to each of these components, are shown.

[0092] exist Figure 3A In the operating mode shown, the potential of the generated particle source is... and extraction aperture potential This results in the particle source potential With extraction aperture potential The voltage between the charged particles is used to extract charged particles from particle source 11. The divergence angle θExt represents the maximum angle between the trajectories of charged particles originating from particle source 11 (at the same point, specifically the peak of the particle source) and capable of passing through extraction aperture 13 and through the aperture 13' of extraction aperture 13.

[0093] exist Figure 3A In the operating mode shown, the divergence angle θ of particle beam 3 remains unchanged downstream of extraction aperture 13. This means that the anode aperture potential... and extraction aperture potential The two are identical, and therefore no electric field acting on the particle beam 3 is generated between the extraction aperture 13 and the anode aperture 14. Therefore, the trajectory of the particles in the particle beam 3 extends in a straight line from the particle source 11 to the anode aperture 14, as shown by the exemplary trajectory 3A.

[0094] Through examples, electric potential and The following values ​​are available in this operating mode:

[0095] and

[0096] like Figure 3A As shown, portion II of the particles in particle beam 3 that has passed through extraction aperture 13 strikes anode aperture 14. Anode aperture 14 blocks portion II of the particles in particle beam 3. Only portion I of the particles in particle beam 3 that is guided to the aperture 14' of anode aperture 14 passes through anode aperture 14. This changes the current intensity of particle beam 3 on anode aperture 14. More precisely, the current intensity of particle beam 3 on anode aperture 14 decreases.

[0097] exist Figure 3B In the operating modes shown, and in Figure 3A The same as generating particle source potential and extraction aperture potential However, with Figure 3A Compared to the example, the anode aperture potential The changes have been made to generate an electric field between the extraction aperture 13 and the anode aperture 14 that has an accelerating effect on the particle beam 3.

[0098] Through examples, electric potential and The following values ​​are available in this operating mode:

[0099] (For example, and

[0100] In this example, the particles in particle beam 3 are accelerated, therefore the divergence angle θ of particle beam 3 between extraction aperture 13 and anode aperture 14 is... Figure 3A The example shown is reduced compared to the example shown. Therefore, the local current intensity of the particle beam in the aperture 14' of the anode aperture 14 is also changed. More precisely, the local current intensity of the particle beam 3 in the aperture 14' of the anode aperture 14 is reduced compared to the example shown. Figure 3A The example shown is increased compared to the example shown. Therefore, the current intensity of the particle beam 3 passing through the anode aperture 14 and the aperture 14' of the anode aperture 14 is changed.

[0101] In other words, due to the reduced divergence angle θ of particle beam 3, the portion II of particles in particle beam 3 that has passed through extraction aperture 13 but is blocked by anode aperture 14 decreases, while the portion I of particles in particle beam 3 that has passed through both extraction aperture 13 and anode aperture 14 increases. This is due to the changed anode aperture potential. The ratio of particles (part I) of the particle beam 3 passing through the aperture 14' of the anode aperture 14 to particles (part II) of the particle beam 3 blocked by the anode aperture 14 has increased.

[0102] exist Figure 3C In the operating modes shown, and in Figure 3A and 3B The same as generating particle source potential and extraction aperture potential However, with Figure 3A and Figure 3B Compared to the example, the anode aperture potential The changes have been made to generate an electric field that has a braking effect on the particle beam 3 between the extraction aperture 13 and the anode aperture 14.

[0103] Through examples, electric potential and The following values ​​are available in this operating mode:

[0104] (For example, and

[0105] In this example, the particles of particle beam 3 are braked, therefore the divergence angle θ of particle beam 3 between extraction aperture 13 and anode aperture 14 is... Figure 3A The example shown is increased compared to the example shown. Therefore, the local current intensity of the particle beam in the aperture 14' of the anode aperture 14 is also changed. More precisely, the local current intensity of the particle beam 3 in the aperture 14' of the anode aperture 14 is compared to... Figure 3A The example shown is reduced compared to the example shown. Therefore, the current intensity of the particle beam 3 passing through the anode aperture 14 and the aperture 14' of the anode aperture 14 is changed.

[0106] In other words, due to the increased divergence angle θ of particle beam 3, the portion II of particles in particle beam 3 that has passed through extraction aperture 13 but is blocked by anode aperture 14 increases, while the portion I of particles in the particle beam that has passed through both extraction aperture 13 and anode aperture 14 decreases. This is due to the changed anode aperture potential. The ratio of particles (part I) of the particle beam 3 passing through the aperture 14' of the anode aperture 14 to particles (part II) of the particle beam 3 blocked by the anode aperture 14 has been reduced.

[0107] It is possible to extract the aperture potential and anode aperture potential The electric field, set in a variable manner, thus achieves a dynamic range of current intensity for the particle beam 3. Therefore, the current intensity of the particle beam 3 passing through the aperture 14' and the anode aperture 14 can be set to a large number of different values ​​other than zero.

Claims

1. A particle beam device (1), comprising: Particle source (11), which is used to provide charged particles; An extraction aperture (13) having an aperture (13'); A driver system (62) is configured to apply an extraction aperture potential (φExt) to the extraction aperture (13), thereby forming a particle beam (3) through the aperture (13') of the extraction aperture (13) by these charged particles; An anode aperture (14) is arranged downstream of the extraction aperture (13) and has an aperture (14') onto which the particle beam (3) is guided during operation; The actuator system (62) is further configured to apply an anode aperture potential (φA) to the anode aperture (14) that can be set in a variable manner and is different from the extraction aperture potential (φExt); a beam tube (23) is arranged downstream of the anode aperture (14) and has an inlet aperture (23') through which the particle beam (3) enters the beam tube (23) during operation; The driver system (62) is also configured to apply a bundle tube potential (φL) to the bundle tube (23) that is different from the anode aperture potential (φA); A controller (61) is configured to control the driver system (62) such that the voltage between the extraction aperture (13) and the anode aperture (14) can be set in a variable manner; The aperture (13') of the extraction aperture (13) is matched with the aperture (14') of the anode aperture (14), such that the current intensity of the particle beam (3) passing through the aperture (14') of the anode aperture (14) can be set in a variable manner by changing the voltage between the extraction aperture (13) and the anode aperture (14).

2. The particle beam device (1) according to claim 1, wherein, The aperture (13') of the extraction aperture (13) and the aperture (14') of the anode aperture (14) are matched to each other, such that the ratio of the particles of the particle beam (3) passing through the aperture (14') of the anode aperture (14) to the particles of the particle beam (3) blocked by the anode aperture (14) can be set in a variable manner by changing the voltage between the extraction aperture (13) and the anode aperture (14).

3. The particle beam device (1) according to claim 1 or 2, wherein, The controller (61) is configured to set the voltage between the extraction aperture (13) and the anode aperture (14) by controlling the driver system (62), so that the particles of the particle beam (3) are accelerated between the extraction aperture (13) and the anode aperture (14).

4. The particle beam device (1) according to claim 1 or 2, wherein, The controller (61) is configured to control the driver system (62) such that the absolute value of the voltage between the extraction aperture (13) and the anode aperture (14) is at least 1 kV.

5. The particle beam device (1) according to claim 1 or 2, in, The driver system (62) is also configured to set the tube potential (φL) in a variable manner.

6. The particle beam device (1) according to claim 1 or 2, in, The controller (61) is configured to generate the anode aperture potential (φA) and the bundle tube potential (φL) by controlling the driver system (62), such that the particles of the particle beam (3) are braked between the anode aperture (14) and the bundle tube (23).

7. The particle beam device (1) according to claim 1 or 2, in, The controller (61) is configured to generate the anode aperture potential (φA) and the bundle tube potential (φL) by controlling the driver system (62), such that the particles of the particle beam (3) are accelerated between the anode aperture (14) and the bundle tube (23).

8. The particle beam device (1) according to claim 1 or 2, wherein, The controller (61) is configured to control the driver system (62) such that the absolute value of the voltage between the anode aperture (14) and the bundle tube (23) is at least 1 kV.

9. The particle beam device (1) according to claim 1 or 2, wherein, The distance (D) between the aperture (13') of the extraction aperture (13) and the inlet aperture (23') of the bundle tube (23) is at least 5 mm and / or at most 20 mm.

10. The particle beam device (1) according to claim 9, wherein, The distance (D) is at most 14 mm.

11. The particle beam device (1) according to claim 9, wherein, The distance (D) is at most 10 mm.

12. The particle beam device (1) according to claim 1 or 2, in, The extraction aperture potential (φExt) can be set by the controller (61) in the range of (φHT+0.5kV) to (φHT+7kV), where φHT indicates the potential applied to the particle source (11), known as the particle source potential. The anode aperture potential (φA) can be set by the controller (61) within the range of -15kV to +15kV, and The tube potential (φL) can be set by the controller (61) in the range of 0kV to 10kV.

13. The particle beam device (1) according to claim 12, in, The actuator system (62) is also configured to apply the particle source potential (φHT) to the particle source (11). The particle source potential (φHT) can be set by the controller (61) in the range of -30kV to -100V.

14. The particle beam device (1) according to claim 12, in, The controller (61) is also configured to change the voltage between the extraction aperture (13) and the anode aperture (14) and, in the process, keep the voltage between the extraction aperture potential (φExt) and the particle source potential (φHT) substantially constant.

15. The particle beam device (1) according to claim 12, further comprising: The sample holder (5) is capable of positioning the sample (4) on the sample holder; The actuator system (62) is also configured to apply a sample potential (φS) to the sample (4) or the sample holder (5); The controller (61) is also configured to change the voltage between the extraction aperture (13) and the anode aperture (14) and to keep the voltage between the sample potential (φS) and the particle source potential (φHT) constant during the process.

16. The particle beam device (1) according to claim 15, in, The sample potential (φS) can be set between -1kV and +1kV.

17. The particle beam device (1) according to claim 15, in, The sample potential (φS) can be set between -5kV and +5kV.

18. The particle beam device (1) according to claim 1 or 2, further comprising: Termination aperture (38) is arranged downstream of the beam tube (23) and has an aperture (38') through which the particle beam (3) passes during operation; The driver system (62) is also configured to apply a termination aperture potential (φT) to the termination aperture (38); The driver system (62) is configured to generate the tube potential (φL) and the termination aperture potential (φT) such that the voltage between the tube (23) and the termination aperture (38) can be set to different values ​​according to the signal from the controller (61).

19. The particle beam device (1) according to claim 18, in, The controller (61) is configured to generate the beam tube potential (φL) and the termination aperture potential (φT) by controlling the driver system (62), such that the particles of the particle beam (3) are braked between the beam tube (23) and the termination aperture (38).

20. The particle beam device (1) according to claim 18, in, The termination aperture potential (φT) can be set between -1kV and +1kV.

21. The particle beam device (1) according to claim 18, in, The termination aperture potential (φT) can be set between -5kV and +5kV.

22. The particle beam device (1) according to claim 1 or 2, further comprising: A multi-aperture aperture gate (40) is arranged in the bundle tube (23) downstream of the inlet aperture (23') and has a plurality of adjacent apertures (41) of different sizes; and A deflection system (43) is configured to selectively deflect the particle beam (3) onto one of the apertures (41) of the multi-aperture aperture (40).

23. The particle beam device (1) according to claim 22, wherein, The multi-aperture orifice gate (40) is a pressure-stage orifice gate, and the vacuum region located upstream of the multi-aperture orifice gate (40) and the vacuum region located downstream of the multi-aperture orifice gate (40) are separated from each other by the pressure-stage orifice gate.

24. The particle beam device (1) according to claim 1 or 2, in, The particle beam device (1) has a first vacuum zone (V1), in which the particle source (11) and the extraction aperture (13) are arranged; The particle beam device (1) has a second vacuum region (V2), and the inlet aperture (23') of the beam tube (23) is arranged in the second vacuum region; and During operation, the first vacuum zone (V1) and the second vacuum zone (V2) maintain different vacuum levels.

25. The particle beam device (1) according to claim 24, wherein, The anode aperture (14) is located at the interface between the first vacuum zone (V1) and the second vacuum zone (V2).

26. The particle beam device (1) according to claim 1 or 2, further comprising: An objective lens (30) is positioned downstream of the inlet aperture (23') of the beam tube (23) and is configured to focus the particle beam (3).

27. A method for controlling a particle beam device (1) according to any one of claims 1 to 26, the method comprising: The voltage between the extraction aperture (13) and the anode aperture (14) is changed in a controlled manner, thereby changing the current intensity of the particle beam (3) passing through the aperture (14') of the anode aperture (14).

28. A computer program product comprising computer-readable instructions that, when executed on a computer, cause the computer to perform the method of claim 27.

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