Electron detection device, electron signal detection method, and electron microscope

Abstract

We provide an electron detection device for electron microscopes. [Solution] The electron detection device 10 includes a first centering assembly 11, a detector assembly 12, a second centering assembly 13, an objective lens 14, and a sample stage 15 for placing a test sample. The first centering assembly 11 deflects the electron beam and offsets it by a first distance from the axis of the electron microscope tube, the second centering assembly 13 re-deflects the electron beam and reduces the distance between the electron beam and the axis of the tube to less than a predetermined distance, the objective lens 14 is used to make the energy of the return electron signal less than the energy of the electron beam, the second centering assembly 13 is further used to deflect the return electron signal and offset the return electron signal by a second distance from the axis of the tube, and the detector assembly is used to receive the deflected return electron signal.

Description

Technical Field

[0001] This application belongs to the technical field of electron microscopes, and particularly relates to an electron detection device, an electron signal detection method, and an electron microscope.

Background Art

[0002] In recent years, electron microscopes have been widely applied in the semiconductor industry. The operating principle of an electron microscope is to use a charged particle beam to impact the surface of a measured object, and a detector detects the electron signal generated in the impacted area to obtain various physical and chemical information of the test sample itself, such as topography, components, characteristic distribution, etc.

[0003] Detectors can be divided into on-axis detectors and off-axis detectors according to their placement positions. In the off-axis detection method, a high-voltage electric field is applied to the off-axis detector, and the electron signal generated by the test sample is collected by the detector under the action of the high-voltage electric field. However, this high-voltage electric field also affects the path of the electron beam moving to the test sample, reducing the quality of the primary electron beam.

[0004] Moreover, the quality of the primary electron beam determines the imaging quality of the electron microscope, and a reduction in the quality of the primary electron beam means a reduction in the imaging quality of the electron microscope.

Summary of the Invention

[0005] Embodiments of this application provide a detection device, an electron signal detection method, and an electron microscope that can avoid applying a high-voltage electric field to an off-axis detector and solve the problem of reducing the quality of the primary electron beam and the imaging quality caused by applying a high-voltage electric field to the off-axis detector.

[0006] According to one aspect, embodiments of this application provide an electron detection device applicable to an electron microscope. The electron detection device includes a first centering assembly, a detector assembly, a second centering assembly, an objective lens, and a sample stage for placing a test sample. The first centering assembly is used to control the deflection of the electron beam and offset the deflected electron beam by a first distance from the axis of the electron microscope tube. The second centering assembly is used to control the re-deflection of the deflected electron beam and to reduce the distance between the re-deflectioned electron beam and the tube axis to less than a predetermined distance. The objective lens is used to focus the electron beam deflected by the second centering assembly and to apply the focused electron beam to the test sample, thereby generating a return electron signal on the test sample under the action of the electron beam. The energy of the return electron signal is less than the energy of the electron beam. The second centering assembly is further used to control the deflection of the return electron signal and to offset the deflected return electron signal by a second distance from the barrel axis. The detector assembly is offset from the barrel axis to avoid the electron beam passing through the first centering assembly. The detector assembly is used to receive the deflected return electron signal.

[0007] In some embodiments, the first centering assembly, the detector assembly, the second centering assembly, the objective lens, and the sample stage are arranged sequentially along the barrel axis, and the first centering assembly includes a first centering member and a second centering member arranged sequentially along the barrel axis direction. The first centering member is used to control the electron beam so that it is deflected by a first predetermined angle away from the axis of the microscope tube. The second centering member is used to control the electron beam, which has been deflected by a predetermined first angle, so that it is deflected again in a direction that approaches the axis of the microscope tube, thereby offsetting the re-deflected electron beam by a first distance from the axis of the microscope tube.

[0008] In some embodiments, the second centering assembly includes a third centering member and a fourth centering member arranged sequentially along the lens barrel axis, The third centering member controls the electron beam to deflect by a second predetermined angle in the direction approaching the axis of the microscope tube. The fourth centering member controls the electron beam, which has been deflected by a second predetermined angle, to be deflected again in a direction away from the axis of the microscope tube, thereby reducing the distance between the re-deflected electron beam and the axis of the microscope tube to less than a predetermined distance.

[0009] In some embodiments, any one of the first centering member, second centering member, third centering member, or fourth centering member includes a first conductive electrode plate and a second conductive electrode plate.

[0010] In some embodiments, any one of the first, second, third, or fourth centering members includes a conductive coil.

[0011] In some embodiments, the detector assembly includes at least one detector, the detector including a receiving surface for receiving a return electronic signal.

[0012] In some embodiments, the receiving surface includes a plurality of sub-receiving surfaces arranged sequentially along the radial direction of the lens barrel, each sub-receiving surface being used to receive a corresponding energy return electron signal.

[0013] In other embodiments, the embodiments of this application provide an electronic signal detection method applicable to the electronic detection device in the above embodiments, wherein the electronic signal detection method is A first electrical signal is applied to a first centering assembly, and the deflection of the electron beam is controlled by the first centering assembly to which the first electrical signal is applied, thereby offsetting the deflected electron beam by a first distance from the axis of the electron microscope's lens barrel. A second electrical signal is applied to the second centering assembly, and the second centering assembly to which the second electrical signal is applied controls the re-deflection of the deflected electron beam, thereby reducing the distance between the re-deflectioned electron beam and the axis of the microscope tube to a predetermined distance. The electron beam, deflected by a second centering assembly to which a second electrical signal is applied, is focused by an objective lens, and the focused electron beam is applied to a test sample placed on a sample stage, thereby generating a return electron signal to the test sample, wherein the energy of the return electron signal is less than the energy of the electron beam. The deflection of the return electron signal is controlled by a second centering assembly to which a second electrical signal is applied, thereby offsetting the deflected return electron signal by a second distance from the barrel axis. This includes receiving a deflected electronic signal by the detector assembly.

[0014] In some embodiments, the detector assembly includes at least one detector, the detector includes a receiving surface, and the receiving surface includes a plurality of sub-receiving surfaces arranged sequentially along the radial direction of the lens barrel. Receiving a deflected electronic signal by the detector assembly is This includes receiving a corresponding energy return electron signal by each sub-receiving surface of the detector in the detector assembly.

[0015] In other embodiments, the embodiments of this application provide an electron microscope equipped with the electron detection device of the above embodiment.

[0016] The electron detection device of the embodiment of this application controls the deflection of the electron beam by a first centering assembly to offset the deflected electron beam by a first distance from the axis of the electron microscope tube, controls the re-deflection of the deflected electron beam by a second centering assembly to reduce the distance between the re-deflectioned electron beam and the axis of the tube to less than a predetermined distance, focuses the electron beam deflected by the second centering assembly with an objective lens, and applies the focused electron beam to a test sample to generate a return electron signal on the test sample under the action of the electron beam, the energy of the return electron signal being less than the energy of the electron beam, controls the deflection of the return electron signal by the second centering assembly to offset the deflected return electron signal by a second distance from the axis of the tube, and the detector assembly is offset from the axis of the tube to avoid the electron beam deflected by the first centering assembly and receives the deflected return electron signal. As can be seen from the following, the embodiment of this application enables the deflection of the electron beam in different directions by the first centering assembly and the second centering assembly in the path along which the electron beam moves to the test sample, allowing the electron beam to act on the test sample according to the direction of electron beam emission, thereby making the return electron signal detected by the detector a valid signal. In the path along which the return electron signal moves, the second centering assembly can enable the deflection of the return electron signal, and because the energy of the return electron signal is less than the energy of the electron beam, the deflection angles of the return electron signal and the electron beam in the second centering assembly are different. The smaller the energy of the electron signal, the larger the deflection angle, which allows the detector not only to avoid the electron beam but also to detect the return electron signal. Furthermore, detection of the return electron signal can be achieved without applying any voltage to the detector, thus avoiding the influence of high-voltage electric fields on the electron beam's path and improving the quality of the electron beam. [Brief explanation of the drawing]

[0017] To more clearly explain the technical solutions of the embodiments of this application, the drawings that need to be used in the embodiments of this application will be briefly described below. For those skilled in the art, other drawings can also be obtained based on these drawings without creative labor. [Figure 1] It is a schematic structural diagram of an exemplary electron microscope. [Figure 2] It is a schematic structural diagram of an electron detection device according to an embodiment of this application. [Figure 3] It is a schematic structural diagram of a first centering assembly according to an embodiment of this application. [Figure 4] It is a schematic structural diagram of a second centering assembly according to an embodiment of this application. [Figure 5] It is a schematic structural diagram of a detector according to an embodiment of this application. [Figure 6] It is a schematic flowchart of an electron signal detection method according to an embodiment of this application. [Figure 7] It is a schematic structural diagram of an electron microscope according to an embodiment of this application.

Embodiments for Carrying Out the Invention

[0018] Hereinafter, the features and exemplary embodiments of each aspect of this application will be described in detail. To more clearly understand the purpose, technical solution and advantages of this application, hereinafter, this application will be described in more detail by referring to the drawings and specific embodiments. The specific embodiments described here are only intended to interpret this application and do not limit this application. For those skilled in the art, this application can be implemented without some of these specific details. The following description of the embodiments is only provided to show examples of this application to better understand this application.

[0019] In this specification, relational terms such as "First" and "Second," etc., are merely used to distinguish one entity or operation from another and do not necessarily require or imply that such an actual relationship or order exists between these entities or operations. Furthermore, the terms "includes," "contains," or any other variation thereof are intended to cover non-exclusive inclusion, and a process, method, article, or device containing a set of elements includes not only those elements but also other elements not explicitly listed, or elements specific to such a process, method, article, or device. Unless further restrictions are found, an element limited by the phrase "...contains" does not preclude the presence of other identical elements in a process, method, article, or equipment containing such elements.

[0020] In recent years, electron microscopes have been widely applied in the semiconductor industry. They detect electron signals generated in a stunned area using a detector to acquire various types of physical and chemical information about the test sample itself, such as topography, components, and feature distribution. Figure 1 shows an exemplary electron microscope, which, as shown in Figure 1, includes an electron beam emission source 101, a detector 102, an objective lens 103, and a sample stage 104. When the electron microscope 100 is operated, a high voltage is applied to the detector 102. After the high voltage is applied to the detector 102, the electron beam emission source 101 emits an electron beam 101a, which acts on the test sample placed on the sample stage along its emission direction, forming a beam spot on the test sample. The test sample generates a return electron signal 101b under the action of the electron beam 101a, and this return electron signal 101b is detected by the detector under the action of a high-voltage electric field.

[0021] The applicant discovered that when using the electron microscope, the high voltage applied to the detector returns to the detector and causes the detection of an electron signal, but it also affects the emitted electron beam, degrading the quality of the electron beam, and further degrading the quality of the beam spot and imaging.

[0022] To solve at least one technical problem in the prior art, embodiments of this application provide an electron detection device. The electron detection device according to embodiments of this application can be applied to an electron microscope.

[0023] Figure 2 is a schematic diagram of the structure of an electronic detection device according to an embodiment of this application.

[0024] Referring to Figure 2, the electronic detection device 10 according to the embodiment of this application may comprise a first centering assembly 11, a detector assembly 12, a second centering assembly 13, an objective lens 14, and a sample stage 15 for placing a test sample, where the first centering assembly 11, the detector assembly 12, the second centering assembly 13, the objective lens 14, and the sample stage 15 are sequentially installed along the axial direction of the lens barrel.

[0025] The first centering assembly 11 is used to control the deflection of the electron beam so that the deflected electron beam is offset by a first distance d1 from the axis m of the electron microscope tube.

[0026] The second centering assembly 13 is used to control the re-deflection of the deflected electron beam, and the distance between the re-deflectioned electron beam and the axis m of the microscope tube can be reduced to less than a predetermined distance.

[0027] The objective lens 14 is used to focus the electron beam deflected by the second centering assembly 13 and to act on the test sample with the focused electron beam, thereby generating a return electron signal on the test sample under the action of the electron beam, and making it possible to make the energy of the return electron signal less than the energy of the electron beam.

[0028] The second centering assembly 13 is also used to control the deflection of the return electron signal, so that the deflected return electron signal is offset by a second distance d2 from the barrel axis m. An electrical signal is applied to the second centering assembly 13, and this electrical signal deflects the direction of motion of the return electron signal.

[0029] The detector assembly 14 is offset from the barrel axis m to avoid the electron beam passing through the first centering assembly 11, and the detector assembly 14 can receive the deflected return electron signal.

[0030] Specifically, the first centering assembly 11 may be located inside the microscope tube of the electron microscope. For example, the first centering assembly 11 may be fixed to the side wall of the microscope tube of the electron microscope. The first centering assembly 11 is distributed symmetrically along the microscope tube axis m. An electrical signal is applied to the first centering assembly 11, and the electron beam is controlled to be deflected away from the microscope tube axis m by the first centering assembly 11 to which the electrical signal is applied. The direction of motion of the deflected electron beam is parallel to the microscope tube axis m and offset by a first distance d1 from the microscope tube axis m of the electron microscope.

[0031] The second centering assembly 13 may be located inside the microscope tube of the electron microscope; for example, the second centering assembly 13 may be fixed to the side wall of the microscope tube. The second centering assembly 13 is distributed symmetrically along the microscope tube axis m. An electrical signal is applied to the second centering assembly 13, and the second centering assembly 13 to which the electrical signal is applied is controlled to deflect the electron beam in a direction toward the microscope tube axis m, thereby reducing the distance between the deflected electron beam and the microscope tube axis m to less than a predetermined distance.

[0032] In some examples, the predetermined distance may be set according to the usage scenario. In this application, the electron detection device is applied to an electron microscope, and in the application scenario of the electron microscope, the settable predetermined distances include, but are not limited to, 0, 10 μm, 30 μm, 50 μm, 70 μm, 100 μm, 150 μm, 200 μm, 250 μm, etc. When the predetermined distance is 0, it means that the deflected electron beam coincides with the axis m of the microscope tube.

[0033] By controlling the distance between the deflected electron beam and the microscope tube axis m to within a predetermined distance, the quality of the beam spot formed when the electron beam acts on the test sample is guaranteed, and a decrease in beam spot quality is avoided.

[0034] The objective lens 14 is located inside the microscope tube of the electron microscope. The objective lens 14 may be an immersion objective lens, a dry objective lens, a semi-immersion objective lens, an electromagnetic composite objective lens, or other types of objective lenses. The objective lens 14 allows the electron beam, which has been deflected via the second centering assembly 13, to be focused onto the test sample.

[0035] The sample stage 15 is located outside the microscope tube of the electron microscope. A deceleration voltage can be applied to the sample stage, and the direction of the deceleration voltage is opposite to the voltage direction of the electron beam emitted from the electron beam emission source. This deceleration of the electron beam acting on the test sample prevents the electron beam energy from being too high and damaging the surface of the test sample.

[0036] The detector assembly 12 is offset at a certain distance from the barrel axis m, thereby avoiding the electron beam and receiving the return electron signal. The detector assembly 12 may be located inside the barrel of the electron microscope; for example, the detector assembly 12 may be fixedly mounted on the side wall of the barrel of the electron microscope.

[0037] The detector assembly 12 may include at least one detector 121. Detector 121 may be a semiconductor detector, a microchannel plate detector, a scintillator detector, or the like.

[0038] The test sample may be a semiconductor wafer, a mask plate, an integrated circuit substrate, or the like.

[0039] The test sample generates a return electron signal, such as a backscattered electron signal or a secondary electron signal, due to the interaction between the electron beam voltage and the deceleration voltage, and the energy of the return electron signal is lower than the energy of the electron beam. The return electron signal passes through a second centering assembly 13 to which an electrical signal is applied, and the second centering assembly 13, to which an electrical signal is applied, controls the return electron signal to be deflected away from the barrel axis m. Because the energy of the return electron signal is lower than the energy of the electron beam, the deflection angle of the return electron signal is larger than the deflection angle of the electron beam, which allows the detector assembly 12 to receive the return electron signal while avoiding the electron beam.

[0040] In the embodiments of this application, the first and second centering assemblies can be used to deflect the electron beam in different directions along the path the electron beam travels to the test sample. By causing the electron beam to act on the test sample according to the direction of electron beam emission, the return electron signal detected by the detector becomes a valid signal. The second centering assembly can deflect the return electron signal along the path of the return electron signal. Since the energy of the return electron signal is less than the energy of the electron beam, the deflection angles of the return electron signal and the electron beam in the second centering assembly are different. As the energy of the electron signal decreases, the deflection angle increases. This allows the detector not only to avoid the electron beam but also to detect the return electron signal. Furthermore, detection of the return electron signal can be achieved without applying any voltage to the detector, and the influence of high-voltage electric fields on the electron beam's path can be avoided, thereby improving the quality of the electron beam.

[0041] Figure 3 is a schematic diagram of the structure of the first centering assembly according to an embodiment of this application.

[0042] In some embodiments, a specific structure of the first centering assembly 11 shown in Figure 2 of this application can be optionally referred to in Figure 3. As shown in Figure 3, the first centering assembly 11 may include a first centering member 111 and a second centering member 112 that are sequentially provided along the axial direction of the microscope tube and in a direction approaching the sample stage 15. The first centering member 111 controls the electron beam to be deflected by a first predetermined angle so that the deflected electron beam moves away from the microscope tube axis m. The second centering member 112 controls the re-deflection of the electron beam deflected by the first predetermined angle so that the re-deflectioned electron beam is offset by a first distance from the microscope tube axis m and parallel to the microscope tube axis m.

[0043] The first centering member 111 receives an electrical signal and controls the electron beam to deflect by a first predetermined angle away from the barrel axis m, but the electrical signal may be a voltage signal or a current signal. For the sake of explanation, in this embodiment, the motion path of the electron beam in the first centering member will be described using the example that the electrical signal is a voltage signal. After the first centering member 111 receives the voltage signal, an electric field is formed in the first centering member 111, and due to the action of the electric field, the electron beam is gradually offset from the barrel axis m along the direction of the electric field until it is offset to a first predetermined angle.

[0044] The first predetermined angle may be understood as the angle between the direction of motion of the electron beam after deflection and the axis m of the microscope tube. The first predetermined angle is determined by an electrical signal applied to the first centering member 111, and the larger the electrical signal, the larger the first predetermined angle.

[0045] The second centering member 112 is used to receive an electrical signal that has the same magnitude as the electrical signal applied to the first centering member, but in the opposite direction, and controls the electron beam, which has been deflected by a predetermined angle, to be deflected in a direction that approaches the barrel axis m. The electrical signal may be a voltage signal or a current signal. For the sake of explanation, in this embodiment, the motion path of the electron beam in the second centering member will be described using the example that the electrical signal is a voltage signal. After the second centering member 112 receives the voltage signal, an electric field is formed in the first centering member 112, and due to the action of the electric field, the electron beam gradually approaches the barrel axis m along the direction of the electric field until it becomes parallel to the barrel axis m.

[0046] By applying electrical signals in opposite directions to the first centering member 111 and the second centering member 112, the electron beam can move along a trajectory parallel to the barrel axis m and separated by a certain distance, and after the electron beam passes through the second centering assembly 13, it can act on the sample in the direction of emission.

[0047] Figure 4 is a schematic diagram of the structure of the second centering assembly according to an embodiment of this application.

[0048] In some embodiments, a specific structure of the second centering assembly 13 shown in Figure 2 of this application can be optionally referred to in Figure 4. As shown in Figure 4, the second centering assembly 13 may include a third centering member 131 and a fourth centering member 132 arranged sequentially along the direction toward the sample stage, the third centering member 131 being used to control the electron beam to be deflected by a second predetermined angle so that the deflected electron beam approaches the barrel axis m, and the fourth centering member 132 being used to control the electron beam deflected by the second predetermined angle so that the distance between the re-deflected electron beam and the barrel axis m is less than a predetermined distance.

[0049] The third centering member 131 is used to receive an electrical signal, the magnitude of which is the same as the magnitude and direction of the electrical signal applied to the second centering member 112. This controls the electron beam deflected by the first centering assembly 11 to deflect by a second predetermined angle in the direction toward the barrel axis m, although the electrical signal may be a voltage signal or a current signal. For the sake of explanation, in this embodiment, the motion path of the electron beam in the third centering member 131 will be described using the example that the electrical signal is a voltage signal. After the third centering member 131 receives the voltage signal, an electric field is formed in the third centering member 131, and due to this electric field, the electron beam is gradually deflected toward the barrel axis m along the direction of the electric field until it is offset to a second predetermined angle.

[0050] The second predetermined angle may be understood as the angle between the direction of motion of the electron beam after it has been deflected by the third centering member 131 and the direction of motion of the electron beam after it has been deflected by the first centering assembly 11 (the direction being parallel to the barrel axis m). The second predetermined angle is determined by an electrical signal applied to the third centering member 131, and the larger the electrical signal, the larger the second predetermined angle. When the voltage applied to the third centering member 131 is equal to the voltage applied to the first centering assembly 11, the second predetermined angle is equal to the first predetermined angle.

[0051] The fourth centering member 132 is used to receive an electrical signal that has the same magnitude as the electrical signal applied to the third centering member 131, but in the opposite direction. This controls the electron beam, which has been deflected by a second predetermined angle, to deflect away from the barrel axis m. The electrical signal may be a voltage signal or a current signal. For the sake of explanation, in this embodiment, the motion path of the electron beam in the fourth centering member 132 will be described using the example that the electrical signal is a voltage signal. After the fourth centering member 132 receives the voltage signal, an electric field is formed in the fourth centering member 132. Due to the action of this electric field, the electron beam, which has been deflected by a second predetermined angle, does not continue to move in the direction of the second predetermined angle, but gradually moves toward the barrel axis m along the direction of the electric field until the distance from the barrel axis m becomes less than a predetermined distance.

[0052] By applying electrical signals in opposite directions to the third centering member 131 and the fourth centering member 132, the trajectory motion of the electron beam, which is parallel to the microscope tube axis m and located at a certain distance from it, is deflected so that it overlaps with the microscope tube, thereby allowing the electron beam to act on the sample in the direction of emission.

[0053] In some embodiments, the centering members, optionally, may include a first centering member 111, a second centering member 112, as shown in Figure 3 of this application, and a third centering member 131, a fourth centering member 132, as shown in Figure 4 of this application.

[0054] The first conductive electrode plate 111a is used for receiving voltage signals or for grounding.

[0055] When the first electrode plate 111a receives a voltage signal, the second electrode plate 111b is used to receive a voltage signal different from the first electrode plate 111a or to ground it, thereby creating a pressure difference between the first electrode plate 111a and the second electrode plate 111b and forming an electric field.

[0056] When the first conductive plate 111a is grounded, the second conductive plate 111b is used to receive a voltage signal, thereby creating a pressure difference between the first conductive plate 111a and the second conductive plate 111b, and thus forming an electric field.

[0057] By applying a voltage to the first conductive plate 111a and the second conductive plate 111b of the first centering member 111, an electric field is formed between the first conductive plate 111a and the second conductive plate 111b of the first centering member 111, and the electron beam that has passed through the first centering member 111 is deflected by a first predetermined angle in the direction of the barrel axis m. By applying a voltage to the first conductive plate 111a and the second conductive plate 111b of the second centering member 112, an electric field is formed between the first conductive plate 111a and the second conductive plate 111b of the second centering member 112, and the electron beam is gradually moved towards the barrel axis m along the direction of the electric field until it becomes parallel to the barrel axis m.

[0058] By applying a voltage to the first conductive electrode plate 111a and the second conductive electrode plate 111b of the third centering member 131, an electric field is formed between the first conductive electrode plate 111a and the second conductive electrode plate 111b of the third centering member, and the electron beam that has passed through the third centering member 131 is deflected by a second predetermined angle in the direction of the lens barrel axis m. By applying a voltage to the first conductive plate 111a and the second conductive plate 111b of the fourth centering member 132, an electric field is formed between the first conductive plate 111a and the second conductive plate 111b of the fourth centering member 132. However, the direction of this electric field is different from the direction of the electric field formed on the third centering member 131. The electron beam, which is deflected by a second predetermined angle in the direction of the barrel axis m, is moved in a direction approaching the barrel axis m in the direction of the barrel axis m until the distance from the barrel axis m becomes less than a predetermined distance. This causes the electron beam to act on the test sample with a predetermined offset from the barrel axis m.

[0059] By applying voltages corresponding to the first conductive electrode plate 111a and the second conductive electrode plate 111b in the first centering member 111 and the second centering member 112, respectively, the electron beam is made to move in a trajectory parallel to the barrel axis m and at a fixed distance away. By applying voltages corresponding to the first conductive electrode plate 111a and the second conductive electrode plate 111b in the third centering member 131 and the fourth centering member 132, respectively, the trajectory motion of the electron beam, which is parallel to the barrel axis m and at a fixed distance away, is deflected so that the distance from the barrel axis m is within a predetermined distance range, thereby causing the electron beam to act on the sample within a predetermined distance range from the barrel axis m.

[0060] In some embodiments, the centering members, optionally, may include a conductive coil, any one of the first centering member 111, the second centering member 112 shown in Figure 3 of this application, and the third centering member 131, the fourth centering member 132 shown in Figure 4 of this application.

[0061] By applying currents corresponding to the conductive coils in the first centering member 111 and the second centering member 112, the electron beam can move along a trajectory parallel to the barrel axis m and at a fixed distance. By applying currents corresponding to the conductive coils in the third centering member 131 and the fourth centering member 132, the trajectory motion of the electron beam, which is parallel to the barrel axis m and at a fixed distance, is deflected so that the distance from the barrel axis m is within a predetermined distance range, thereby causing the electron beam to act on the sample within a predetermined distance range from the barrel axis m.

[0062] In some embodiments, the detector 121 shown in Figure 2 of this application may optionally include a receiving surface located on the side of the detector closer to the objective lens, the receiving surface which can be used to receive a return electron signal.

[0063] Since the energies of the electron beam and the return electron signal are different, their deflection angles are different, and the smaller the energy, the larger the deflection angle. Therefore, the movement trajectories of the return electron signal and the electron beam are different. Therefore, after the second centering assembly 13 controls the deflection of the return electron signal, the second distance d2 from the deflected return electron signal to the lens barrel axis m is greater than the first distance d1 from the deflected electron beam to the lens barrel axis m, and the distance D from the detector to the lens barrel axis m satisfies d1 < D < d2 with the first distance d1 and the second distance d2, and the detector 121 can collect the return electron signal through the receiving surface.

[0064] FIG. 5 is a schematic structural view of a detector according to an embodiment of the present application.

[0065] In some embodiments, optionally, for the specific structure of the detector 121 shown in FIG. 2 of the present application, reference may be made to FIG. 5. As shown in FIG. 5, the detector 121 may include a plurality of sub-receiving surfaces 41 sequentially arranged along the radial direction of the lens barrel, and each sub-receiving surface 41 can be used to receive return electron signals of different energies.

[0066] The return electron signal deflects after passing through the second centering assembly 13. Since the energies of the return electron signals are different, the deflection angles of the return electron signals are different. After passing through the second centering assembly 13 and deflecting, when acting on the receiving surface of the detector, the distances from the lens barrel axis m are different. The greater the energy of the return electron signal, the closer it is to the lens barrel axis m. Therefore, return electron signals of different energies can be collected by a plurality of sub-receiving surfaces 41 sequentially arranged along the radial direction of the lens barrel, and return electron signals of different energies can be imaged separately in the electron microscope.

[0067] In some embodiments, optionally, the electronic detection device shown in FIG. 2 of the present application may further include a signal synthesizer (not shown), and the number of signal synthesizers may be set according to usage needs. The signal synthesizer is connected to a plurality of sub-receiving surfaces, synthesizes the return electron signals detected by the plurality of sub-receiving surfaces, and outputs an electronically synthesized image signal, and is used to realize hybrid imaging.

[0068] To better understand the embodiments of the present application, the movement processes of the electron beam and the return electron signal in the electronic detection device shown in FIG. 2 will be described below with reference to FIG. 2. In the electronic detection device shown in FIG. 2, the electron beam reflection source is coaxial with the lens barrel of the electron microscope, the first centering assembly 11 is symmetric with respect to the lens barrel axis m, the second centering assembly 13 is symmetric with respect to the lens barrel axis m, and the detector assembly 12 includes a detector 121, and the detector 121 is located on one side of the lens barrel axis m. The distance from the first centering assembly 11 to the lens barrel axis m is

Number

Number

[0069] The energy of the electron beam emitted from the electron beam emission source is E1, and for example, it may be 10 keV, 12 keV, 14 keV, 16 keV, etc. This energy can also be represented by the acceleration voltage U1. For example, if the energy of the electron beam is 10 keV, the acceleration voltage corresponding to this electron beam is 10 kV. The deceleration energy applied to the sample stage is E2, and E2 < E1 may be true. For example, E2 may be 500 eV, 800 eV, 1 keV, 2 keV, 3 keV, etc. This deceleration energy can also be represented by the deceleration voltage U2, whereby the equivalent voltage U3 of the generated return electron signal is U3 = U1 - U2.

[0070] A voltage ΔV1 is applied to the first centering assembly 11, and a voltage ΔV2 is applied to the second centering assembly 13. The effective length of the first centering assembly 11 is h1, and the effective length of the second centering assembly 13 is h2. Here, the effective length may be understood as the length of the region in the first centering assembly or the second centering assembly that deflects the electron beam.

[0071] Voltage ΔV1 includes sub-voltages ΔV'1 and ΔV''1. The values ​​of sub-voltages ΔV'1 and ΔV''1 are the same as the value of voltage ΔV1, and the directions of sub-voltages ΔV'1 and ΔV''1 are opposite. Sub-voltage ΔV'1 corresponds to the first field region 101 of the first centering assembly 11, and sub-voltage ΔV''1 corresponds to the second field region 102 of the first centering assembly 11. Under the action of sub-voltages ΔV'1 and ΔV''1, the first centering assembly 11 forms sub-electric fields ΔE'1 and ΔE''1, respectively, and sub-electric fields ΔE'1 and ΔE''1 are perpendicular to the barrel axis m, and the directions of sub-electric fields ΔE'1 and ΔE''1 are opposite. As the electron beam passes through the first centering assembly 11, it first passes through the region where the sub-field ΔE'1 is located, causing the electron beam to undergo a first deflection along the direction of the sub-field ΔE'1, with a deflection angle of α. At this time, the direction of motion of the electron beam and the axis of the microscope tube m have a deflection angle of α. Subsequently, it passes through the region where the sub-field ΔE''1 is located, causing the electron beam to undergo a second deflection along the direction of the sub-field ΔE''1, with a deflection angle of α. At this time, the direction of motion of the electron beam is parallel to the axis of the microscope tube m and is located at a first distance d1 from the axis of the microscope tube m, where,

number

[0072] In the example shown in Figure 2 of this application, the direction of the sub-electric field ΔE'1 is in the X direction and the direction of the sub-electric field ΔE''1 is in the Y direction, but the invention is not limited to these directions. The direction of the sub-electric field ΔE'1 is determined by ΔV'1 of the first field region 101 in the first centering assembly 11, where ΔV'1 indicates the potential difference formed by the first centering assembly 11 in the first field region 101. The direction of the sub-electric field ΔE''1 is determined by ΔV''1 of the second field region 102 in the first centering assembly 11, where ΔV''1 indicates the potential difference formed by the first centering assembly 11 in the second field region 102.

[0073] The voltage ΔV2 includes sub-voltages ΔV'2 and ΔV''2. The values ​​of sub-voltages ΔV'2 and ΔV''2 are the same as the value of voltage ΔV2, but their directions are opposite. Sub-voltage ΔV'2 corresponds to the first field region of the second centering assembly 13, and sub-voltage ΔV''2 corresponds to the second field region of the second centering assembly 13. Under the action of sub-voltages ΔV'2 and ΔV''2, the second centering assembly 13 forms sub-electric fields ΔE'2 and ΔE''2, respectively, and these sub-electric fields ΔE'2 and ΔE''2 are perpendicular to the barrel axis m, and their directions are opposite. As the electron beam passes through the second centering assembly 13, it first passes through the region where the sub-electric field ΔE'2 is located, causing the electron beam to undergo a first deflection along the direction of the sub-electric field ΔE'2, with a deflection angle of β. Next, it passes through the region where the sub-electric field ΔE''2 is located, causing the electron beam to undergo a second deflection along the direction of the sub-electric field ΔE''2, with a deflection angle of β. At this time, the direction of motion of the electron beam coincides with or nearly coincides with the barrel axis m. Whether the magnitudes of the deflection angles α and β are the same depends on whether the voltages ΔV2 and ΔV1 are the same, and the voltages ΔV2 and ΔV1 can be artificially controlled. In this embodiment, by explaining that the voltages ΔV2 and ΔV1 are equal, the electron beam can be directed along the barrel axis m to strike the test sample, thereby ensuring the quality of the electron beam spot on the test sample.

[0074] In the example shown in Figure 2 of this application, the direction of the sub-electric field ΔE'2 is the Y direction and the direction of the sub-electric field ΔE''2 is the X direction, but the application is not limited to these. The direction of the sub-electric field ΔE'2 is determined by ΔV'2 of the first field region in the second centering assembly 13, where ΔV'2 represents the potential difference formed by the second centering assembly in the first field region. The direction of the sub-electric field ΔE''2 is determined by ΔV''2 of the second field region in the second centering assembly 13, where ΔV''2 represents the potential difference formed by the second centering assembly in the second field region.

[0075] The electron beam focused by the objective lens 14 acts on the test sample placed on the sample stage 15, and the test sample generates a return electron signal with an energy of E3.

[0076] When the return electron signal passes through the second centering assembly 13, it first passes through the region where the sub-field ΔE'2 is located, causing the return electron signal to undergo a first deflection along the direction of the sub-field ΔE'2, with a deflection angle of γ. Since the energy of the return electron signal is less than the energy of the electron beam, the deflection angle γ of the return electron signal is greater than the deflection angle β of the electron beam. Subsequently, it passes through the region where the sub-field ΔE''2 is located, causing the return electron signal to undergo a second deflection along the direction of the sub-field ΔE''2, with a deflection angle of γ. At this point, the direction of motion of the return electron signal is parallel to the barrel axis m and is a first distance d2 away from the barrel axis m of the electron microscope, where,

number

[0077] The return electronic signal passes through the second centering assembly 13 and is then collected by the detector.

[0078] In this example, the field region can be understood as the electric field region formed in the centering assembly.

[0079] In this example, the first centering assembly 11 and the second centering assembly 13 can deflect the electron beam in different directions along the path the electron beam travels to the test sample, allowing the electron beam to act on the test sample according to the direction of electron beam emission, and enabling the return electron signal detected by the detector 121 to be used as a valid signal. In the path of the return electron signal, the second centering assembly 13 can deflect the return electron signal, and because the energy of the return electron signal is smaller than the energy of the electron beam, the deflection angles of the return electron signal and the electron beam in the second centering assembly 13 are different. The smaller the energy of the electron signal, the larger the deflection angle. In this way, the detector 121 can detect the return electron signal without interrupting the path from the electron beam to the test sample, and furthermore, the return electron signal can be collected without applying any voltage to the detector 121, thus avoiding the influence of high-voltage electric fields on the electron beam path and improving the quality of the electron beam.

[0080] To better understand the embodiments of this application, the motion processes of the return electron signals of different energies in the electronic detection device shown in Figure 2 of this application will be described below with reference to Figure 5.

[0081] The return electron signal may contain electron signals of multiple energies, and the detector 121 can simultaneously collect electron signals of different energies via different sub-receiving surfaces 41. The lower the energy of the return electron signal, the greater the distance from the lens barrel axis m.

[0082] The voltage of the electron signal with maximum energy in the return electron signal is U max Assuming that ΔU is the pressure difference between the electron signals of other energies and the electron signal with the maximum energy, the distance L from the axis of the microscope tube when the return electron signal is collected by the detector can be expressed as follows.

number

[0083] In the example shown in Figure 5, the detector may include multiple sub-receiving surfaces 41. Each sub-receiving surface 41 receives a return electron signal of a different energy. For example, if the voltage is U m To obtain a return electron signal, the region corresponding to the return electron signal of that energy can be obtained by calculation, and the return electron signal received by the sub-receiving surface 41 where that region is located can be obtained and imaged using a microscope.

[0084] Each sub-receiving surface 41 receives a return electron signal with a different energy, thereby enabling the electron microscope to independently image the return electron signals with different energies.

[0085] Different energies in the return electron signals result in different deflection angles of the second centering assembly 13 relative to the return electron signals. After being deflected by the second centering assembly 13, the return electron signals act on the receiving surface of the detector, resulting in different distances from the microscope tube axis m. The greater the energy of the return electron signals, the closer they are to the microscope tube axis m, allowing multiple sub-receiving surfaces 41, which are sequentially arranged along the radial direction of the microscope tube, to collect return electron signals of different energies, enabling the electron microscope to independently image return electron signals of different energies.

[0086] Based on the above-described detection device, the embodiments of this application further provide an electronic signal detection method.

[0087] Figure 6 is a schematic flowchart of an electronic signal detection method according to an embodiment of the present application. As shown in Figure 6, the electronic signal detection method according to the present application may include the following steps.

[0088] In S10, a first electrical signal is applied to the first centering assembly, and the deflection of the electron beam is controlled by the first centering assembly to which the first electrical signal is applied, thereby offsetting the deflected electron beam by a first distance from the axis of the electron microscope's lens barrel.

[0089] In S11, a second electrical signal is applied to the second centering assembly, and the second centering assembly to which the second electrical signal is applied controls the re-deflection of the deflected electron beam, thereby reducing the distance between the re-deflectioned electron beam and the axis of the microscope tube to less than a predetermined distance.

[0090] In S12, the objective lens focuses the electron beam deflected by the second centering assembly to which the second electrical signal is applied, and the focused electron beam acts on the test sample placed on the sample stage, thereby generating a return electron signal to the test sample, but the energy of the return electron signal is less than the energy of the electron beam.

[0091] In S13, the deflection of the return electron signal is controlled by the second centering assembly to which the second electrical signal is applied, thereby offsetting the deflected return electron signal by a second distance from the lens barrel axis.

[0092] In S14, the deflected return electronic signal is received by the detector assembly.

[0093] In this embodiment, by applying a first electrical signal to the first centering assembly and a second electrical signal to the second centering assembly, the electron beam can be deflected in different directions by the first and second centering assemblies along the path in which the electron beam moves to the test sample. This allows the electron beam to act on the test sample according to the direction of electron beam emission, and as a result, the return electron signal detected by the detector is a valid signal. The second centering assembly can deflect the return electron signal along the path in which the return electron signal moves. Since the energy of the return electron signal is less than the energy of the electron beam, the deflection angles of the return electron signal and the electron beam in the second centering assembly are different. The smaller the energy of the electron signal, the larger the deflection angle. In this way, the detector can detect the return electron signal without interrupting the path in which the electron beam moves to the test sample. Furthermore, since the return electron signal can be collected without applying any voltage to the detector, the influence of high-voltage electric fields on the electron beam's path can be avoided, and the quality of the electron beam can be improved.

[0094] In some embodiments, step S14 in the electronic signal detection method shown in Figure 6 of this application may optionally include receiving the corresponding energy return electronic signal by each sub-receiving surface of the detector in the detector assembly.

[0095] Different energies in the return electron signals result in different deflection angles of the second centering assembly relative to the return electron signals. After being deflected by the second centering assembly, the return electron signals act on the receiving surface of the detector, resulting in different distances from the tube axis. The greater the energy of the return electron signals, the closer they are to the tube axis, allowing multiple sub-receiving surfaces arranged sequentially along the radial direction of the tube to collect return electron signals of different energies, enabling the electron microscope to image return electron signals of different energies independently.

[0096] Based on the above-described detection device, embodiments of this application further provide an electron microscope.

[0097] Figure 7 is a schematic diagram of the structure of an electron microscope according to an embodiment of this application. As shown in Figure 7, the electron microscope 1 may include an electron beam emission source 3 and an electron detection device 10 as shown in Figure 2.

[0098] Electron microscopes include, but are not limited to, transmission electron microscopes, scanning electron microscopes, and scanning transmission electron microscopes.

[0099] Applications of electron microscopes include, but are not limited to, the detection of patterns and measurement of critical dimensions on semiconductor silicon wafers and mask plates, and the detection of open and short faults in electronic elements on integrated circuit substrates.

[0100] In this embodiment, the electron microscope can achieve deflection of the electron beam in different directions by the first and second centering assemblies in the electron detection device along the path the electron beam travels to the test sample. This allows the electron beam to act on the test sample according to the direction of electron beam emission, and as a result, the return electron signal detected by the detector in the electron detection device is a valid signal. The second centering assembly in the electron detection device can achieve deflection of the return electron signal along its path. Since the energy of the return electron signal is less than the energy of the electron beam, the deflection angles of the return electron signal and the electron beam in the second centering assembly are different. The smaller the energy of the electron signal, the larger the deflection angle. This allows the detector to not only avoid the electron beam but also detect the return electron signal. Furthermore, since detection of the return electron signal can be achieved without applying any voltage to the detector, the influence of high-voltage electric fields on the electron beam's path is avoided, improving the quality of the electron beam and the imaging quality of the electron signal.

[0101] The above are merely specific embodiments of the present application, and for the convenience and brevity of explanation, those skilled in the art can refer to the corresponding processes in the embodiments of the above methods for the specific operating processes of the systems, modules, and units described above, and will omit further explanation here. The scope of protection of this application is not limited thereto, and those skilled in the art will readily conceive of various equivalent modifications or substitutions within the technical scope disclosed herein, and will understand that any such modifications or substitutions should fall within the scope of protection of this application.

Claims

1. An electron detection device applied to an electron microscope, It comprises a first centering assembly, a detector assembly, a second centering assembly, an objective lens, and a sample stage for placing a test sample. The first centering assembly is used to control the deflection of the electron beam and to offset the deflected electron beam by a first distance from the axis of the electron microscope tube. The second centering assembly is used to control the re-deflection of the deflected electron beam and to reduce the distance between the re-deflectioned electron beam and the barrel axis to less than a predetermined distance. The objective lens is used to focus the electron beam deflected by the second centering assembly and to act on the test sample with the focused electron beam, thereby generating a return electron signal on the test sample under the action of the electron beam, the energy of which the return electron signal is less than the energy of the electron beam. The second centering assembly is further used to control the deflection of the return electron signal and to offset the deflected return electron signal by a second distance from the barrel axis. The detector assembly is offset from the barrel axis to avoid the electron beam that has passed through the first centering assembly. An electronic detection device characterized in that the detector assembly is used to receive the deflected return electronic signal.

2. The first centering assembly, the detector assembly, the second centering assembly, the objective lens, and the sample stage are sequentially arranged along the axis of the lens barrel. The first centering assembly includes a first centering member and a second centering member that are sequentially provided along the axial direction of the lens barrel, The first centering member is used to control the electron beam so that it is deflected by a first predetermined angle away from the axis of the lens barrel. The electron detection device according to claim 1, characterized in that the second centering member is used to control the electron beam, which has been deflected by a first predetermined angle, to be deflected again in a direction approaching the axis of the microscope tube, thereby offsetting the re-deflected electron beam by a first distance from the axis of the microscope tube.

3. The second centering assembly includes a third centering member and a fourth centering member that are sequentially provided along the axial direction of the lens barrel, The third centering member is used to control the electron beam so that it is deflected by a second predetermined angle in the direction approaching the axis of the lens barrel. The electron detection device according to claim 2, characterized in that the fourth centering member is used to control the electron beam, which has been deflected by a second predetermined angle, to be deflected again in a direction away from the axis of the microscope tube, thereby reducing the distance between the re-deflected electron beam and the axis of the microscope tube to less than a predetermined distance.

4. The electronic detection device according to claim 3, characterized in that any one of the centering members among the first centering member, the second centering member, the third centering member, or the fourth centering member includes a first conductive electrode plate and a second conductive electrode plate.

5. The electronic detection device according to claim 3, characterized in that any one of the first centering member, the second centering member, the third centering member, or the fourth centering member includes a conductive coil.

6. The detector assembly includes at least one detector, The electronic detection device according to claim 1, characterized in that the detector includes a receiving surface for receiving a return electronic signal.

7. The receiving surface includes a plurality of sub-receiving surfaces arranged sequentially along the radial direction of the lens barrel. The electronic detection device according to claim 6, characterized in that each of the sub-receiving surfaces is used to receive a corresponding energy return electronic signal.

8. An electronic signal detection method applicable to an electronic detection device according to any one of claims 1 to 7, A first electrical signal is applied to a first centering assembly, and the deflection of the electron beam is controlled by the first centering assembly to which the first electrical signal is applied, thereby offsetting the deflected electron beam by a first distance from the axis of the microscope tube. A second electrical signal is applied to the second centering assembly, and the second centering assembly to which the second electrical signal is applied controls the re-deflection of the deflected electron beam, thereby reducing the distance between the re-deflectioned electron beam and the axis of the microscope tube to a predetermined distance. The electron beam, deflected by the second centering assembly to which the second electrical signal is applied, is focused by an objective lens, and the focused electron beam is applied to the test sample placed on the sample stage, thereby generating a return electron signal to the test sample, wherein the energy of the return electron signal is less than the energy of the electron beam. The deflection of the return electron signal is controlled by the second centering assembly to which the second electrical signal is applied, thereby offsetting the deflected return electron signal by a second distance from the lens barrel axis. An electronic signal detection method characterized by comprising receiving the deflected return electronic signal by the detector assembly.

9. The detector assembly includes at least one detector, the detector includes a receiving surface, and the receiving surface includes a plurality of sub-receiving surfaces arranged sequentially along the radial direction of the lens barrel. The detection assembly receives the deflected return electron signal, The method according to claim 8, characterized in that each sub-receiving surface of the detector in the detector assembly receives a corresponding energy return electron signal.

10. An electron microscope characterized by comprising an electron detection device according to any one of claims 1 to 7.

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