CHARGE BEAM DEVICE

Abstract

In the present invention, the visibility of a region that is difficult to observe can be improved. A charged particle beam device 100 irradiates a sample with a charged particle beam 121 to obtain an observation image of the sample. The charged particle beam device 100 includes: an electron gun 101 that emits a primary electron beam 121; and an energy discriminator 200 disposed between the electron gun 101 and a sample 111, and having a first region for discriminating signal particles 122 according to the energy emitted by the sample 111 irradiated with the charged particle beam 121, and a second region that transmits signal particles 122.

Description

Technical area

[0001] The present disclosure relates to a charged particle beam device. State of the art

[0002] With the miniaturization of semiconductor devices and the shift to 3D devices, the number of areas where signal detection is difficult, such as the bottom portion of a deep trench pattern, is increasing, and there is a growing need to observe such areas. Therefore, a scanning electron microscope (SEM) used to examine and measure semiconductor devices must have higher sensitivity and accuracy than those of the prior art.

[0003] To examine and measure the bottom portion of the trench-shaped pattern, it is effective to selectively detect only electrons emitted in a specific direction among electrons emitted from a sample. Therefore, there is a need for a configuration that reduces the detection of electrons emitted from portions other than the bottom portion and efficiently detects electrons emitted from the bottom portion.

[0004] PTL 1 discloses a method of forming a hole for conducting electrons in a reflector, deflecting electrons of a desired component by a secondary electron deflector provided below the reflector so that the electrons pass through the hole, and deflecting the electrons by another secondary electron deflector after passing through the reflector so that they reach a detector. Citation listPatent literature

[0005] PTL1: JP6820660B Summary of the inventionTechnical problem

[0006] According to the above-described technique in PTL 1, electrons emitted from a sample are deflected to pass through the through-hole formed in the reflector, and thus, an electron detection range may be limited. However, in the above-described technique in PTL 1, since electrons leak from the through-hole in the reflector, the deflector for changing the electrons passing through the through-hole of the reflector and the detector for detecting the electrons passing through the through-hole in the reflector are required, so such a device configuration is complex.

[0007] The disclosure has been made to solve the problem described above, and an object thereof is to provide a charged particle beam device that can improve the visibility of a region that is difficult to observe by using an energy discriminator. Solution to the problem

[0008] To solve the above-described problem, a charged particle beam device according to the disclosure is a charged particle beam device that irradiates a sample with a charged particle beam to obtain an observation image of the sample, the charged particle beam device comprising: a charged particle beam source configured to emit the charged particle beam; and an energy discriminator disposed between the charged particle beam source and the sample, the energy discriminator having a first region for discriminating according to the energy of a signal particle emitted from the sample irradiated with the charged particle beam and a second region that transmits the signal particle. Advantageous effects of the invention

[0009] According to the disclosure, in a charged particle beam device, the visibility of a region that is difficult to observe can be improved by using an energy discriminator.

[0010] Problems, configurations and effects other than those described above will be clarified by the following description of embodiments. Brief description of the drawings [ Fig. 1] Fig. 1 is a view illustrating an overall configuration of a charged particle beam device according to a first embodiment. [ Fig. 2A] Fig. 2A is a view illustrating a power filter in the first embodiment. [ Fig. 2B] Fig. 2B is a view illustrating the energy filter in the first embodiment. [ Fig. 3A] Fig. 3A is a view illustrating a relationship between a negative voltage VEF and the number of signal particles passing through the energy filter in the first embodiment. [ Fig. 3B] Fig. 3B is a view illustrating the relationship between the negative voltage VEF and the number of signal particles passing through the energy filter in the first embodiment. [ Fig. 4A] Fig. 4A is a view illustrating trajectories of electrons emitted from an upper layer portion and a trench bottom portion of a sample in the first embodiment. [ Fig. 4B] Fig. 4B is a view illustrating an azimuth angle and an elevation angle of an electron emitted from the sample in the first embodiment. [ Fig. 5A] Fig. 5A is a view illustrating a distribution of signal particles on a reflector reaching the reflector from a surface layer portion of the sample in the first embodiment. [ Fig. 5B] Fig. 5B is a view illustrating a distribution of signal particles on the reflector reaching the reflector from a trench bottom portion of the sample in the first embodiment. [ Fig. 6A] Fig. 6A is a view illustrating a detection range of all signal particles reaching the reflector from the surface layer portion of the sample in the first embodiment. [ Fig. 6B] Fig. 6B is a view illustrating a detection range of all signal particles reaching the reflector from the trench bottom portion of the sample in the first embodiment. [ Fig. 6C] Fig. 6C is a view illustrating the visibility of the trench bottom portion when all signal particles reaching the reflector are detected in the first embodiment. [ Fig. 6D] Fig. 6D is a view illustrating the visibility of the trench bottom portion when all signal particles reaching the reflector are detected in the first embodiment. [ Fig. 7A] Fig. 7A is a view illustrating a detection range with a large number of signal particles from the trench bottom portion among the signal particles reaching the reflector from the surface layer portion of the sample in the first embodiment. [ Fig. 7B] Fig. 7B is a view illustrating a detection range of signal particles from the trench bottom portion of the sample in the first embodiment among the signal particles reaching the reflector from the trench bottom portion. [ Fig. 7C] Fig. 7C is a view illustrating the visibility of the trench bottom portion when only a detection range with a large number of signal particles from the trench bottom portion among the signal particles reaching the reflector is detected in the first embodiment. [ Fig. 7D] Fig. 7D is a view illustrating the visibility of the trench bottom portion when only an area having a large number of signal particles from the trench bottom portion among the signal particles reaching the reflector is detected in the first embodiment. [ Fig. 8] Fig. 8 is a view illustrating an example of an energy filter enabling azimuth angle discrimination in the first embodiment. [ Fig. 9A] Fig. 9A is a view illustrating a stacked structure of an energy filter enabling azimuth angle discrimination in a second embodiment. [ Fig. 9B] Fig. 9B is a view illustrating a structure of each grating of the energy filter enabling azimuth angle discrimination in the second embodiment. [ Fig. 10A] Fig. 10A is a view illustrating a stacked structure of an energy filter enabling azimuth angle discrimination in a first modification of the second embodiment. [ Fig. 10B] Fig. 10B is a view illustrating a structure of each grating of the energy filter enabling azimuth angle discrimination in the first modification of the second embodiment. [ Fig. 11] Fig. 11 is a view illustrating a structure of each energy filter grid in a second modification of the second embodiment. [ Fig. 12A] Fig. 12A is a view illustrating a structure of an energy filter grid in a third modification of the second embodiment. [ Fig. 12B] Fig. 12B is a view illustrating the structure of the energy filter grid in the third modification of the second embodiment. [ Fig. 12C] Fig. 12C is a view illustrating the structure of the energy filter grid in the third modification of the second embodiment. [ Fig. 12D] Fig. 12D is a view illustrating the structure of the energy filter grid in the third modification of the second embodiment. [ Fig. 13] Fig. 13 is a view in which a primary electron beam is deflected by an electric field due to an energy filter. [ Fig. 14] Fig. 14 is a view in which a center tube is provided to an energy filter in a third embodiment. [ Fig. 15A] Fig. 15A is a view illustrating signal particles detected by azimuth angle discrimination in a fourth embodiment. [ Fig. 15B] Fig. 15B is a view illustrating signal particles detected by energy discrimination in the fourth embodiment. [ Fig. 16A] Fig. 16A is a view illustrating a discrimination method for combining the azimuth angle discrimination and the energy discrimination in the fourth embodiment. [ Fig. 16B] Fig. 16B is a view illustrating the discrimination method for combining the azimuth angle discrimination and the energy discrimination in the fourth embodiment. [ Fig. 17] Fig. 17 is a view illustrating a positional relationship between a reflector and an energy filter in a fifth embodiment. [ Fig. 18A] Fig. 18A is a view showing a shape of a general reflector. [ Fig. 18B] Fig. 18B is a view illustrating a shape of the reflector in the fifth embodiment. [ Fig. 19] Fig. 19 is a view illustrating an azimuth angle discrimination method by the reflector in the fifth embodiment. [ Fig. 20] Fig. 20 is a view illustrating a configuration in which the reflector and the energy filter are combined in the fifth embodiment. [ Fig. 21A] Fig. 21A is a view illustrating an example of an energy filter enabling azimuth angle discrimination and elevation angle discrimination in a sixth embodiment. [ Fig. 21B] Fig. 21B is a view illustrating an example of an energy filter grating enabling elevation angle discrimination in a modification of the sixth embodiment. [ Fig. 22] Fig. 22 is a view illustrating an example of a structure of a rotary energy filter grid in a seventh embodiment. [ Fig. 23] Fig. 23 is a view illustrating an example of a power filter grid capable of controlling a voltage of each of a plurality of mesh electrodes in an eighth embodiment. Description of embodiments

[0011] Embodiments according to the disclosure will be described in detail with reference to the drawings. In the following embodiments, it is understood that a configuration (including steps in a flowchart) thereof is not necessarily essential unless otherwise stated or unless clearly considered essential in principle. Preferred embodiments of the disclosure will be described below with reference to the drawings. [First embodiment]

[0012] A first embodiment is described with reference to Fig. 1 to 8 described. (Charged beam device 100)

[0013] First, an overall configuration of a charged particle beam device 100 will be described with reference to Fig. 1. The charged particle beam device 100 of the first embodiment is an electron microscope. The charged particle beam device 100 irradiates a sample 111 with a charged particle beam to obtain an observation image of the sample 111. The charged particle beam device 100 includes an electron gun 101, a condenser lens 102, a condenser lens 103, a diaphragm 104, a reflector 105, an ExB deflector 106, a detector 107, a deflector 108, a deflector 109, an objective lens 110, a sample stage 112, a delay power supply 113, a display 114, a storage device 115, and a control device 120. The control device 120 is a device that controls an operation and the like of each unit, and is a computer system including a processor, a memory, and the like. The storage device 115 stores a control table 116 containing control conditions such asa voltage and current of each unit are defined. The control device 120 reads the control table 116 from the storage device 115 and controls each unit based on the control conditions defined in the control table 116.

[0014] The electron gun 101 is an electron source that emits electrons. The electron gun 101 is an example of a charged particle beam source in the disclosure. A negative voltage of, for example, 3000 V is applied to the electron source. The condenser lens 102 and the condenser lens 103 are lenses that focus a primary electron beam 121. The aperture 104 is an element that determines an angular spread of the primary electron beam 121 at the objective lens 110 and has a hole through which the primary electron beam 121 passes. The deflector 108 and the deflector 109 deflect the primary electron beam 121 to scan the sample 111.

[0015] The objective lens 110 is a lens that focuses the deflected primary electron beam 121 and narrows the primary electron beam 121 by a magnetic field generated by a current flowing through an internal coil.

[0016] The sample stage 112 holds the sample 111 and controls a position and attitude of the sample 111. That is, the sample stage 112 moves the sample 111 in a horizontal direction or a vertical direction, or rotates the sample 111 in the vertical direction, which serves as a rotation axis. The deceleration power supply 113 for applying a voltage to the sample stage 112 is connected to the sample stage 112. By applying a negative voltage of several kV to the sample stage 112, an electric field for decelerating the primary electron beam 121 is formed between the sample 111 and the objective lens 110. When the sample 111 is irradiated with the decelerated primary electron beam 121, signal particles 122 are emitted from the sample 111.In general, signal particles emitted with an energy of 50 eV or less are called secondary electrons, and signal particles emitted with an energy greater than 50 eV and close to that of the primary electron beam 121 are called backscattered electrons.

[0017] The electric field that slows down the primary electron beam 121 also has a function of accelerating the signal particles 122 generated at the sample 111. The signal particles 122, advancing upward, collide with the reflector 105. When the signal particles 122 collide with the reflector 105, tertiary electrons 123 are emitted from the reflector 105. The tertiary electrons 123 are deflected by an electric field and a magnetic field in the ExB deflector 106 and detected by the detector 107. The electric field and the magnetic field in the ExB deflector 106 also act on the primary electron beam 121, and since the effects of the electric field and the magnetic field cancel each other out for the primary electron beam 121, the primary electron beam 121 travels straight toward the sample 111.

[0018] The charged particle beam device 100 further includes an energy filter 200. The energy filter 200 is provided directly below the ExB deflector 106 and can distinguish the signal particles 122 based on energy. (Energy Filter 200)

[0019] A structure of the energy filter 200 is described with reference to Fig. 2A and Fig. 2B. The energy filter 200 is an example of an energy discriminator in the disclosure. The energy filter 200 is arranged between the electron gun 101 and the sample 111. As shown in Fig. As shown in Figure 2A, the power filter 200 includes grounded conductor grids 201, a power filter grid 202 that allows a voltage to be applied, and a power filter power supply 203 connected to the power filter grid 202 so that it can apply the voltage. The conductor grids 201 are arranged above and below the power filter grid 202. As shown in Fig. As shown in Figure 2B, a mesh electrode 204 is provided on a mesh fixing support 205 in each conductor grid 201 and energy filter grid 202. Holes 210 through which the primary electron beam 121 passes are provided in the mesh electrodes 204 of the conductor grid 201 and the energy filter grid 202.

[0020] A potential barrier is formed by applying a negative voltage VEF to the energy filter grid 202 through the energy filter power supply 203. Among the signal particles 122 incident on the energy filter 200, signal particles 124 with an energy E lower than the potential barrier are reflected back, and only the signal particles 122 with the energy E higher than the potential barrier pass through the energy filter 200 and collide with the reflector 105. Then, the tertiary electrons 123 generated at the reflector 105 are detected by the detector 107.

[0021] (Relationship between applied voltage of the energy filter 200 and number of signal particles passing through the energy filter 200)

[0022] How the number of signal particles passing through the energy filter 200 is changed by the negative voltage VEF applied to the energy filter 200 will be explained here with reference to Fig. 3A and Fig. 3B. As described in Fig. 3A, it is ideal for energy discrimination to detect all electrons with an energy that exceeds the negative voltage VEF without detecting all electrons with an energy that is lower than the negative voltage VEF. If only one energy filter grid 202 is present, as shown in Fig. As shown in Figure 3B, electrons with an energy lower than the negative voltage VEF are also detected, and consequently, the energy discrimination performance deteriorates. To prevent this, it is preferable to provide two or more energy filter grids 202. Here, the number of energy filter grids 202 may be one or more. (Detection range of signal particles 122)

[0023] In semiconductor device observation, there is an increasing need to observe a region where signal detection is difficult, such as a trench bottom portion of a trench-shaped pattern. Detecting only secondary electrons emitted in a specific direction is an effective method for observing and investigating a shape of the trench bottom portion of the trench-shaped pattern. One reason for this will be explained with reference to Fig. 4A to 7D.

[0024] One factor that makes it difficult to observe a trench bottom portion 401 of a trench-shaped pattern 400 is that the number of signal particles 122 emitted from the trench bottom portion 401 is smaller than the number of signal particles 122 emitted from a surface layer portion 410. Fig. 4A illustrates trajectories of the signal particles 122 emitted from the trench bottom portion 401 of the trench-shaped pattern 400. Among the signal particles 122 emitted from the trench bottom portion 401 of the trench-shaped pattern 400, the signal particles 122 that collide with a wall surface 402 of the trench-shaped pattern 400 do not reach the detector 107, and thus, the detectable signal particles 122 from the trench bottom portion 401 are only those emitted in a direction where the wall surface 402 is absent.

[0025] As in Fig. 4B, here, an X-axis and a Y-axis are taken in a planar direction, a Z-axis is taken in an optical beam axis direction, an angle between the emission direction of the signal particles 122 and the Z-axis is defined as an elevation angle 131, and an angle between the emission direction of the signal particles 122 and the X-axis is defined as an azimuth angle 132. A discrimination method for discriminating the signal particles 122 based on the elevation angle 131 and detecting only the signal particles 122 emitted almost directly above the sample 111 is called elevation angle discrimination, and a discrimination method for discriminating the signal particles 122 based on the azimuth angle 132 and detecting only the signal particles 122 emitted in a specific direction such as a longitudinal direction of the groove-shaped pattern 400 is called azimuth angle discrimination.

[0026] Fig. 5A and Fig. 5B illustrates a distribution of the signal particles 122 emitted from the sample 111 and reaching the reflector 105. For the signal particles 122 emitted from the surface layer portion 410, since there is no obstacle such as the wall surface 402 on a path reaching the reflector 105, the signal particles 122 emitted in any direction reach the reflector 105 and have an isotropic distribution as shown in Fig. 5A. Since the signal particles 122 emitted from the trench bottom section 401 do not reach the reflector 105 when they collide with the wall surface 402, as shown in Fig. 5B, the signal particles 122 have a distribution that is elongated in a direction corresponding to the longitudinal direction of the trench-shaped pattern 400 in which the wall surface is missing. In the example of Fig. 5A and Fig. 5B, all signal particles 122 that reach the reflector 105 are detected.

[0027] Fig. 6A illustrates a detection range 600 of the signal particles 122 reaching the reflector 105 from the surface layer portion 410, and Fig. 6B illustrates the detection range 600 of the signal particles 122 reaching the reflector 105 from the trench bottom section 401. In the detection range 600, as in Fig. 6C, there is a large difference in the detection amount between the trench bottom portion 401 and the surface layer portion 410. When an SEM image is generated in this state, as shown in Fig. 6D, a minute change in the signal amount of the trench bottom portion 401 is not displayed in an observation image as a difference of gradation values.

[0028] Therefore, as in Fig. 7A and Fig. 7B, a detection range 700 is limited to only an area with a large number of signal particles 122 from the trench bottom section 401. Consequently, as shown in Fig. 7C, the signal particles 122 from the surface layer portion 410 are reduced while the detection amount of the signal particles 122 from the trench bottom portion 401 is maintained, and the detection amount of the signal particles 122 from the trench bottom portion 401 approaches the detection amount of the surface layer portion 410. When an SEM image is generated in this state, as shown in Fig. 7D, a minute change in the signal amount is emphasized, and the change in the signal amount of the trench bottom portion 401 can be checked as a contrast in the image.

[0029] It is also effective to limit the detection range based on the elevation angle and detect only the signal particles 122 emitted almost directly above the sample 111, and when there is no wall surface in the longitudinal direction of the trench-shaped pattern 400 or the like, by limiting the detection range to be elongated in one direction as shown in Fig. 7A and Fig. 7B, a relatively large number of signal particles 122 can be detected from the trench bottom section 401, thereby achieving better efficiency. (Azimuth angle discrimination by the energy filter 200)

[0030] In the first embodiment, a method is proposed using the energy filter 200 to detect only the signal particles 122 emitted in a specific direction extending along the longitudinal direction of the groove-shaped pattern 400. This method will be described with reference to Fig. 8 described.

[0031] As in Fig. As shown in Figure 8, the mesh electrode 204 provided on the energy filter grid 202 is divided into, for example, four sections in a circumferential direction, and only sections in a specific diagonal direction are provided in the mesh fixing support 205. When the negative voltage VEF is applied to the energy filter grid 202, the potential barrier is formed only in a region AR1 (first region) where the mesh electrode 204 is provided. The signal particles 122 emitted toward the region AR1 where the mesh electrode 204 is provided are reflected back by the potential barrier and do not reach the detector 107. It is also possible to detect only the signal particles 122 emitted toward a region AR2 (second region) where the mesh electrode 204 is not provided, and thus, azimuth angle discrimination can be implemented.

[0032] Fig. 8 illustrates, as an example, a structure in which two divided mesh electrodes 204 are provided in the horizontal direction to enable observation of the trench bottom portion 401 of the trench-shaped pattern 400 extending along the vertical direction. An installation position of the mesh electrode 204 can be freely determined in a vertical direction, an oblique direction, or the like according to the longitudinal direction of the trench-shaped pattern 400, which is an observation target. The mesh electrode 204 of the conductor grid 201 is not divided. (Effects of the first embodiment)

[0033] As in Fig. As shown in Figure 8, by creating the region AR1 in which the signal particles 122 are discriminated according to energy and the region AR2 that allows the signal particles 122 to pass through in the energy filter grid 202, it is possible to reduce the signal particles 122 from a portion corresponding to the region AR1 (for example, the surface layer portion 410) while maintaining the detection amount of the signal particles 122 from a portion corresponding to the region AR2 (for example, the trench bottom portion 401). Consequently, the detection amount of the signal particles 122 from the portion corresponding to the region AR2 approaches the detection amount of the signal particles 122 from the portion corresponding to the region AR1. When an SEM image is generated in this state, as shown in Figure 8, Fig. 7D, a minute change in signal amount is emphasized, and the change in signal amount of the portion corresponding to the area AR2 can be checked as a contrast in the image. [Second embodiment]

[0034] Next, a second embodiment will be described with reference to Fig. 9A to 12D. Matters described in the first embodiment and not described in the second embodiment are also applicable to the second embodiment unless there are special circumstances.

[0035] In the energy filter 200 shown in the first embodiment, the direction in which the signal particles 122 can be distinguished is set to the direction in which the mesh electrode 204 of the energy filter grid 202 is provided, and is restricted to a specific direction such as only the vertical direction. Therefore, in the second embodiment, as shown in Fig. 9A, energy filter grids 202 are stacked in the direction of the optical axis. As shown in Fig. As shown in Figure 9B, the area AR1 in which the mesh electrode 204 of the energy filter grid 202 is provided restricts the range in the azimuth angle direction of the signal particles 122 differently for each energy filter grid 202. Specifically, in a first energy filter grid 202, the area AR1 in which the mesh electrode 204 is provided is located, for example, in the horizontal direction, and in a second energy filter grid 202, the area AR1 in which the mesh electrode 204 is provided is located, for example, in the vertical direction. An insulation member 206 that insulates the mesh electrodes 204 from each other is provided between the energy filter grids 202, and a negative voltage VEF of any magnitude can be applied to each energy filter grid 202. At the time of azimuth angle discrimination of the signal particles 122, the negative voltage VEF is applied to one of the energy filter grids 202 according to a pattern on the sample 111. (First modification of the second embodiment)

[0036] As in Fig. 10A and Fig. As shown in Figure 10B, in addition to the energy filter grid 202 having the mesh electrode 204 in the vertical direction and the energy filter grid 202 having the mesh electrode 204 in the horizontal direction as described above, two types of energy filter grids 202 having mesh electrodes 204 in oblique directions may be added, and a total of four energy filter grids 202 may be stacked via insulation members 206. Consequently, azimuth angle discrimination is enabled not only in the vertical direction and the horizontal direction, but also in the oblique directions. (Second modification of the second embodiment)

[0037] Although an example has been described in which the mesh electrode 204 is divided into four sections and two opposing sections are provided, the mesh electrode 204 may be finely divided into four or more sections as shown in Fig. 11. In the case of Fig. 11, azimuth angle discrimination can be implemented by applying the voltage not only to the energy filter grid 202 in which the mesh electrode 204 is provided in a region to be detected, but by applying the negative voltage VEF to other energy filter grids 202. (Third modification of the second embodiment)

[0038] The mesh electrode 204 provided on the energy filter grid 202 may have any shape as long as the mesh electrode 204 can detect only the signal particles 122 emitted in a specific direction. Fig. 12A to 12D show installation examples of the mesh electrode 204. In the energy filter grid 202 in Fig. 12A, only half of the grid electrode 204 is provided, and the signal particles 122 emitted either to the left and right sides or to the top and bottom sides can be distinguished. A side surface of the pattern with a height in the direction of the optical axis can thus be observed, for example. In the energy filter grid 202 in Fig. 12B, by providing the divided mesh electrode 204 for each energy filter grid 202, it is possible to freely change a discrimination condition according to a pattern, such as setting a discriminable area not in diagonal directions but to half discrimination as in Fig. 12A. In the energy filter grid 202 in Fig. 12C, the detection range can be increased by further dividing the mesh electrode 204 into Fig. 12B into eight sections. In the energy filter grid 202 in Fig. 12D, the mesh electrode 204 is not divided in the circumferential direction, but is provided in the vertical direction according to a narrow elongated distribution of the signal particles 122 emitted from the trench bottom portion 401. (Effects of the second embodiment)

[0039] In the second embodiment, the plurality of energy filter grids 202 are stacked in the optical axis direction, and the direction in which the mesh electrode 204 is provided is a direction different for each energy filter grid 202, thereby enabling the azimuth angle discrimination of the signal particles 122 according to the pattern of the sample 111 or the like. [Third Embodiment]

[0040] A third embodiment is described with reference to Fig. 13 and Fig. 14. Matters described in the first embodiment and the second embodiment and not described in the third embodiment are also applicable to the third embodiment unless there are special circumstances.

[0041] Since the negative voltage VEF of several kV is applied to the energy filter grid 202 in the above-described configuration of the energy filter 200, when the primary electron beam 121 passes through a center of the energy filter 200, as shown in Fig. 13, the primary electron beam 121 is influenced by an electric field of the energy filter grid 202 and is deflected. Therefore, in the third embodiment, as shown in Fig. 14, a central tube 207 made of metal is provided in the center of the energy filter 200. By providing the central tube 207, even if a voltage is applied to the energy filter grid 202, the primary electron beam 121 can pass through the energy filter 200 without being affected. A diameter of the central tube 207 is approximately 1 mm. The central tube 207 is connected to both of two conductor grids 201 in Fig. 14 and alternatively, the central tube 207 may be connected to only one of the two conductor grids 201. (Effects of the third embodiment)

[0042] By providing the central tube 207, the primary electron beam 121 is not affected by the electric field of the energy filter 200. Consequently, the beam diameter of the primary electron beam 121 is not affected, and an effect of reducing positional deviation and focus blur on the sample 111 is obtained. Even if the negative voltage VEF applied to the energy filter grid 202 by the energy filter power supply 203 is changed, it is not necessary to correct the position and focus, and an optimal applied voltage condition can be smoothly sought. [Fourth Embodiment]

[0043] A fourth embodiment is described with reference to Fig. 15A to 16B. Matters described in the first embodiment to the third embodiment and not described in the fourth embodiment are also applicable to the fourth embodiment unless there are special circumstances.

[0044] As described in the second embodiment, a voltage can be applied to each of the plurality of energy filter grids 202, and the applied voltage can be freely changed for each of the energy filter grids 202. By changing the applied voltage VEF, it is possible to perform energy discrimination as in the prior art, in addition to discrimination based on the emission direction of the signal particles 122.

[0045] As in Fig. 15A, the above-described azimuth angle discrimination of the signal particles 122 is a discrimination based on the azimuth angle direction of the signal particles 122. All signal particles 122 emitted to a detectable area pass through. As shown in Fig. 15B, an energy filter in the prior art also discriminates energy based on the energy of the signal particles 122. All signal particles 122 having an energy equal to or higher than the negative voltage VEF set by the energy filter power supply 203 pass through.

[0046] As in Fig. As shown in Figure 16A, by combining discrimination based on the emission direction of the signal particles 122 and discrimination based on the amount of energy, it is possible to detect only the signal particles 122 emitted in a specific direction and having high energy, such as backscattered electrons. In the azimuth angle discrimination in the above-described embodiment, no voltage is applied to the mesh electrode 204 in the region to be detected, but in the fourth embodiment, by applying a negative voltage Ve to the mesh electrode 204 in the region to be detected in the energy filter grid 202, it is possible to allow only the signal particles 122 with an energy equal to or higher than the applied negative voltage Ve to pass through.At this time, the applied negative voltage Ve has a value smaller than the negative voltage VEF applied to the grid electrode 204 in a non-detectable area for azimuth angle discrimination. Furthermore, by applying the negative voltage Ve to all energy filter grids 202, it is possible to perform energy discrimination as in the prior art.

[0047] By applying no voltage to a particular energy filter grid 202, applying the negative voltage Ve to one of the remaining energy filter grids 202 and applying the negative voltage VEF to the other energy filter grids 202, as in Fig. 16B, it is possible to perform discrimination in which all the signal particles 122 in the direction of the energy filter grid 202 to which no voltage is applied are detected, only the signal particles 122 having an energy equal to or higher than Ve are detected in the direction of the energy filter grid 202 to which the negative voltage Ve is applied, and the other signal particles 122 are not detected. (Effects of the fourth embodiment)

[0048] In the fourth embodiment, by controlling the voltage applied to the mesh electrode 204, it is possible to perform energy discrimination as in the prior art in addition to the azimuth angle discrimination based on the emission direction of the signal particles 122. [Fifth Embodiment]

[0049] A fifth embodiment is described with reference to Fig. 17 to 20. Matters described in the first embodiment to the fourth embodiment and not described in the fifth embodiment are also applicable to the fifth embodiment unless there are special circumstances.

[0050] As in Fig. As shown in Figure 17, reflector 105 is provided above energy filter 200. Reflector 105 is an example of a conversion electrode in the disclosure. Signal particles 122 passing through energy filter 200 collide with reflector 105, and the generated tertiary electrons 123 (secondary signal particles) are detected by detector 107.

[0051] As in Fig. As shown in Figure 18A, the general reflector 105 is a circular metal plate having a hole in its center through which the primary electron beam 121 passes.

[0052] In the fifth embodiment, the reflector 105 is divided to perform azimuth angle discrimination of the signal particles 122. As shown in Fig. As shown in Figure 18B, the reflector 105 is first divided in a circumferential direction. The divided regions 105a to 105h of the reflector 105 are not in contact with each other, and a voltage can be applied to each region. A positive voltage Vh, as desired, is applied to a region other than a region to be detected, and no voltage is applied to the region to be detected.

[0053] Fig. Figure 19 shows trajectories of the signal particles 122 colliding with the divided reflector 105 and the tertiary electrons 123 generated at the reflector 105. The tertiary electrons 125 generated in the region to which the positive voltage Vh is applied are drawn back to the reflector 105 due to the applied positive voltage Vh and do not reach the detector 107. Meanwhile, only the tertiary electrons 123 generated by colliding with the region to which no voltage is applied are detected by the detector 107. (Effects of the fifth embodiment)

[0054] As in Fig. As shown in Figure 20, the signal particles 122 can be discriminated twice using the reflector 105 and the energy filter 200 in combination. As described in the fourth embodiment, since the energy filter 200 can also perform energy discrimination, for example, the energy filter 200 can discriminate secondary electrons, and the reflector 105 can discriminate backscattered electrons. [Sixth Embodiment]

[0055] A sixth embodiment is described with reference to Fig. 21. Matters described in the first embodiment to the fifth embodiment and not described in the sixth embodiment are also applicable to the sixth embodiment unless there are special circumstances.

[0056] When observing the trench-shaped pattern, in addition to azimuth angle discrimination, elevation angle discrimination for detecting the signal particles 122 emitted almost directly above the sample 111 is also an effective method. The energy filter 200, which can perform both azimuth angle discrimination and elevation angle discrimination, is described with reference to Fig. 21 described.

[0057] By combining an elevation angle discrimination energy filter grid 208 with a different central area size in addition to the energy filter grid 202, in which the mesh electrode 204 divided for azimuth angle discrimination is provided, elevation angle discrimination is enabled in addition to azimuth angle discrimination. The elevation angle discrimination energy filter grid 208 for elevation angle discrimination restricts a range of the signal particles 122 in an elevation angle direction. The elevation angle discrimination energy filter grid 208 (second energy filter grid) has a central area AR3 that is larger than the central area AR3 of the energy filter grid 202 (first energy filter grid) for azimuth angle discrimination.

[0058] As in Fig. 21B, the elevation angle discrimination energy filter grid 208 may be provided with the central region AR3 which is an opening near the center, and the mesh electrode 204 may be provided on an entire outer periphery of the central region AR3. (Effects of the sixth embodiment)

[0059] When the elevation angle discrimination is performed, a negative voltage VEF is applied to the elevation angle discrimination energy filter grid 208 whose central area AR3 is large, the signal particles 124 are reflected back, and consequently, only the signal particles 122 passing between the elevation angle discrimination energy filter grid 208 and the central tube 207 and emitted near the center can be detected.

[0060] By combining azimuth angle discrimination and elevation angle discrimination, signal particles within a narrow elevation angle range emitted in a specific direction can be detected. As described in the fourth embodiment, energy discrimination is also enabled by changing the voltage VEF applied to the energy filter grid 202, and, for example, only backscattered electrons within a specific elevation angle range can be detected. [Seventh Embodiment]

[0061] A seventh embodiment is described with reference to Fig. 22. Matters described in the first embodiment to the sixth embodiment and not described in the seventh embodiment are also applicable to the seventh embodiment unless there are special circumstances.

[0062] The energy filter 200 has a structure in which the energy filter grid 202, which is provided with the divided mesh electrode 204, is rotatable. In the structures described up to the sixth embodiment, a region in which the mesh electrode 204 is provided cannot be changed after the energy filter 200 is provided in the electron microscope. As shown in Fig. Therefore, as shown in Figure 22, a mechanism is provided in which a rotating mechanism 209 is provided on the energy filter grid 202 so that the energy filter grid 202 is rotatable. The rotating mechanism 209 in the seventh embodiment displaces the area AR1 in which the mesh electrode 204 is provided and the opening area AR2 by rotating the energy filter grid 202. Alternatively, the area AR1 and the area AR2 may be displaced by a mechanism other than the rotating mechanism 209. The rotating mechanism 209 is an example of a displacement unit in the disclosure. (Effects of the Seventh Embodiment)

[0063] Using the rotation mechanism 209, the area where the mesh electrode 204 is provided moves, and a discrimination range can be changed even after the energy filter 200 is installed in the electron microscope. The rotation mechanism 209 can finely adjust the discrimination range according to the pattern of the sample 111.

[0064] The rotating mechanism 209 may be any mechanism as long as the area in which the mesh electrode 204 is provided can be changed after the installation of the energy filter 200. The energy filter grid 202 is Fig. 22 and alternatively, for example, the entire energy filter grid 200 can be rotated. [Eighth Embodiment]

[0065] An eighth embodiment is described with reference to Fig. 23. Matters described in the first embodiment to the seventh embodiment and not described in the eighth embodiment are also applicable to the eighth embodiment unless there are special circumstances.

[0066] As in Fig. As shown in Fig. 23, the mesh electrode 204 provided on the energy filter grid 202 is divided into, for example, eight sections in the circumferential direction, and the negative voltage VEF can be applied to each mesh electrode 204. When the negative voltage VEF is applied to the desired mesh electrode 204, the potential barrier is formed only in a region where the mesh electrode 204 to which the negative voltage VEF is applied is provided. The signal particles 122 emitted in a direction in which the mesh electrode 204 is provided are reflected back by the potential barrier and do not reach the detector 107, and only the signal particles 122 emitted in a direction in which the mesh electrode 204 to which the negative voltage VEF is not applied is provided can be detected, thereby implementing azimuth angle discrimination. (Effects of the eighth embodiment)

[0067] When the energy filter grid 202 is used in the eighth embodiment, an energy filter (for example, Fig. 11 and 12A to 12C) having different potential barriers can be implemented by an energy filter grid 202 by controlling the application of the negative voltage VEF to the plurality of mesh electrodes 204.

[0068] The disclosure is not limited to the above-described embodiments and includes various modifications. The above-described embodiments are described in detail to facilitate understanding of the disclosure, and the disclosure is not necessarily limited to those having all of the described configurations. A part of a configuration in one embodiment may be replaced with a configuration in another embodiment, and a configuration in one embodiment may also be added to a configuration in another embodiment. Another configuration may be added to a part of a configuration in each embodiment, and a part of a configuration in each embodiment may also be deleted or replaced with another configuration. List of reference symbols 101 Electron source (charge beam source) 102 Condenser lens 103 Condenser lens 104 aperture 105 Reflector 106 ExB deflector 107 Detector 108 Deflector 109 Deflector 110 objective lens 111 Sample 112 Sample table 113 Delay power supply 114 Advertisement 115 Storage device 116 Tax table 120 Control device 121 Primary electron beam 122 signal particles 123 tertiary electrons 124 signal particles (reflected back by energy filter and not detected) 125 tertiary electron (pulled back by the divided reflector and not detected) 131 Elevation angle 132 azimuth angles 200 Energy Filter (Energy Discriminator) 201 ladder grid 202 Energy filter grids 203 Energy filter power supply 204 mesh electrode 205 mesh fixation supports 206 Insulation element 207 central tube 208 elevation angle discrimination energy filter grids 209 Rotating mechanism (displacement unit) 210 holes 400 trench pattern 401 trench floor section 402 wall surface 410 Surface layer section 600 detection range 700 detection range (with limited range in azimuth angle direction) AR1 area (first area) AR2 area (second area) AR3 central area QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 6820660B

[0005]

Claims

[1] A charged particle beam device that irradiates a sample with a charged particle beam to obtain an observation image of the sample, the charged particle beam device comprising: a charged particle beam source configured to emit the charged particle beam; and an energy discriminator arranged between the charged particle beam source and the sample, the energy discriminator having a first region for discriminating according to the energy of a signal particle emitted from the sample irradiated with the charged particle beam and a second region transmitting the signal particle. [2] Charged carrier beam device according to claim 1, wherein the energy discriminator includes a mesh electrode provided in the first area, and a power supply that applies a voltage to the grid electrode. [3] A charged particle beam device according to claim 2, wherein the second region is an opening that allows the charged particle beam to pass therethrough. [4] A charged particle beam device according to claim 1, wherein the first region is provided corresponding to a direction of a groove-shaped pattern of the sample to restrict a range of the signal particle in an azimuth angle direction. [5] Charge beam device according to claim 1, wherein the energy discriminator comprises a plurality of energy filter grids, each having the first region and the second region, the plurality of energy filter grids are stacked in a direction of the optical axis of the charged particle beam, and the first areas of the energy filter grids limit the ranges of the signal particles in an azimuth angle direction differently for the respective energy filter grids. [6] A charged particle beam device according to claim 5, wherein the plurality of energy filter grids are stacked over an insulation member insulating between the mesh electrodes. [7] A charged particle beam device according to claim 1, wherein the energy discriminator comprises a metal tube that allows the charged particle beam from the charged particle beam source to pass through the sample toward the sample. [8] A charged particle beam device according to claim 1, further comprising: a conversion electrode configured to allow the signal particle passing through the energy discriminator to collide with it to generate a secondary signal particle; and a detector configured to detect the secondary signal particle. [9] The charged particle beam device according to claim 1, wherein the energy discriminator comprises a first energy filter grid having the first region and the second region and a second energy filter grid for restricting a range of the charged particle beam in an elevation angle direction. [10] A charged particle beam device according to claim 1, further comprising: a displacement unit configured to displace the first region and the second region.

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