Charged particle beam apparatus and control method for charged particle beam apparatus

Abstract

To provide a charged particle beam apparatus capable of introducing a sample into a sample chamber without lowering a degree of vacuum of the sample chamber.SOLUTION: A charged particle beam apparatus includes: a sample chamber 202, a preliminary exhaust chamber 232 connected to the sample chamber 202; a main exhaust pump 510 whose first port 512 is connected to the sample chamber 202 and second port 514 is connected to the preliminary exhaust chamber 232; a sub-exhaust pump 520 connected to the preliminary exhaust chamber 232, an exhaust port 516, and the sample chamber 202; and a control unit that controls the main exhaust pump 510 and the sub-exhaust pump 520. The control unit performs: processing of causing the sub-exhaust pump 520 to exhaust the preliminary exhaust chamber 232 when the sample is introduced into the preliminary exhaust chamber 232; processing of determining whether a degree of vacuum of the preliminary exhaust chamber 232 has reached a predetermined degree of vacuum based on electric power of the sub-exhaust pump 520; and processing of causing the main exhaust pump 510 to exhaust the preliminary exhaust chamber 232 when it is determined that the degree of vacuum of the preliminary exhaust chamber 232 has reached the predetermined degree of vacuum.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a charged particle beam device and a method for controlling the charged particle beam device. [Background technology]

[0002] In charged particle beam devices such as transmission electron microscopes, scanning electron microscopes, and focused ion beam devices, when a sample is introduced into a sample chamber, pre-evacuation is performed to prevent a decrease in the degree of vacuum in the sample chamber.

[0003] For example, in Patent Document 1, a sample is introduced into a pre-exhaust chamber, which is then evacuated with a vacuum pump. After confirming that the degree of vacuum in the pre-exhaust chamber is higher than the desired degree of vacuum, a gate valve separating the pre-exhaust chamber from the sample chamber is opened, and the sample is introduced into the sample chamber. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-118056 Summary of the Invention [Problem to be solved by the invention]

[0005] In such a charged particle beam device, it is desirable to be able to introduce the sample from the pre-evacuation chamber into the sample chamber without reducing the degree of vacuum in the sample chamber. [Means for solving the problem]

[0006] One aspect of the charged particle beam device according to the present invention is A charged particle beam device that irradiates a sample with a charged particle beam, a sample chamber in which the sample is placed; a preliminary exhaust chamber connected to the sample chamber via a gate valve; a first exhaust pump having a first port, a second port, and an exhaust port, the first port being connected to the sample chamber and the second port being connected to the pre-exhaust chamber; a second exhaust pump connected to the preliminary exhaust chamber, the exhaust port, and the sample chamber; a control unit that controls the first exhaust pump and the second exhaust pump; Including, When the sample is introduced into the pre-evacuation chamber, the control unit a process of evacuating the preliminary exhaust chamber with the second exhaust pump; a process of determining whether the degree of vacuum in the preliminary exhaust chamber has reached a first degree of vacuum based on the power of the second exhaust pump; a process of causing the first exhaust pump to exhaust the preliminary exhaust chamber when it is determined that the degree of vacuum in the preliminary exhaust chamber has reached the first degree of vacuum; Do the following.

[0007] In such a charged particle beam device, the pre-exhaust chamber can be evacuated using the first exhaust pump, which reduces the decrease in vacuum level in the sample chamber when the gate valve is opened to introduce a sample from the pre-exhaust chamber into the sample chamber. Furthermore, in such a charged particle beam device, the vacuum level in the pre-exhaust chamber is determined from the power of the second exhaust pump, so a vacuum gauge for measuring the vacuum level in the pre-exhaust chamber is not required. Therefore, the number of parts in such a charged particle beam device can be reduced.

[0008] One aspect of a method for controlling a charged particle beam device according to the present invention includes: a sample chamber in which a sample is placed; a preliminary exhaust chamber connected to the sample chamber via a gate valve; a first exhaust pump having a first port, a second port, and an exhaust port, the first port being connected to the sample chamber and the second port being connected to the pre-exhaust chamber; a second exhaust pump connected to the preliminary exhaust chamber, the exhaust port, and the sample chamber; A method for controlling a charged particle beam device, comprising: When the sample is introduced into the pre-evacuation chamber, causing the second exhaust pump to evacuate the pre-evacuation chamber; determining whether the degree of vacuum in the preliminary exhaust chamber has reached a first degree of vacuum based on the power of the second exhaust pump; when it is determined that the degree of vacuum in the preliminary exhaust chamber has reached the first degree of vacuum, causing the first exhaust pump to evacuate the preliminary exhaust chamber; Includes.

[0009] In this control method for a charged particle beam device, the first exhaust pump is used to evacuate the pre-exhaust chamber, thereby reducing the decrease in the vacuum level in the sample chamber when the gate valve is opened to introduce a sample from the pre-exhaust chamber into the sample chamber. Furthermore, in this control method for a charged particle beam device, the vacuum level in the pre-exhaust chamber is determined from the power of the second exhaust pump, eliminating the need for a vacuum gauge to measure the vacuum level in the pre-exhaust chamber. Therefore, this control method for a charged particle beam device reduces the number of parts. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a transmission electron microscope according to a first embodiment. [Figure 2] FIG. [Figure 3] FIG. [Figure 4] FIG. 2 is a diagram showing an example of the configuration of a vacuum exhaust system. [Figure 5] 10 is a flowchart showing an example of a control process of the vacuum exhaust system when exhausting the sample chamber. [Figure 6] 10 is a flowchart showing an example of a control process of the vacuum pumping system when a sample is introduced into a sample chamber. [Figure 7] 10 is a flowchart showing an example of a control process of a vacuum exhaust system during microscopic examination. [Figure 8] 10 is a flowchart showing a modified example of the control process of the vacuum exhaust system during microscopic examination. [Figure 9] 10 is a flowchart showing an example of a control process of the vacuum exhaust system when no microscopy is performed. [Figure 10]FIG. 2 is a diagram schematically illustrating a GUI (Graphical User Interface) screen. [Figure 11] FIG. 2 is a diagram schematically illustrating a GUI screen. [Figure 12] FIG. 10 is a diagram showing a modified example of the configuration of the vacuum exhaust system. [Figure 13] 10 is a flowchart showing an example of a control process of the vacuum exhaust system when no microscopy is performed. [Figure 14] FIG. 10 is a diagram showing a modified example of the configuration of the vacuum exhaust system. DETAILED DESCRIPTION OF THE INVENTION

[0011] Preferred embodiments of the present invention will be described in detail below with reference to the drawings. Note that the embodiments described below do not unduly limit the content of the present invention as defined in the claims. Furthermore, not all of the configurations described below are necessarily essential components of the present invention.

[0012] Furthermore, the following describes a case where the charged particle beam device according to the present invention is a transmission electron microscope that irradiates a sample with an electron beam, but the charged particle beam device according to the present invention may also be a device that irradiates a sample with a charged particle beam other than an electron beam (such as an ion beam).

[0013] 1. First embodiment 1.1. Transmission electron microscope 1.1.1. Configuration of a transmission electron microscope First, a transmission electron microscope according to the first embodiment will be described with reference to the drawings. Fig. 1 is a diagram showing an example of the configuration of a transmission electron microscope 2 according to the first embodiment.

[0014] As shown in FIG. 1, the transmission electron microscope 2 includes a housing 100, a main body 200, a sample holder 300, a control unit 400, and a vacuum exhaust system 500.

[0015] The housing 100 houses a main body 200 of the transmission electron microscope 2, a control unit 400, and a vacuum pumping system 500.

[0016] The main body 200 includes an electron gun 210, an irradiation optical system 220 for irradiating the sample S with electrons emitted from the electron gun 210, a holder support part 230 having an insertion port through which the sample holder 300 can be inserted and removed, an imaging optical system 240 for forming an image of the electrons that have passed through the sample S, an imaging device 250 for taking a transmission electron microscope image (TEM image) formed by the electrons that have passed through the sample S, and a detector 260 for detecting the electrons that have passed through the sample S to obtain a scanning transmission electron microscope image (STEM image). The irradiation optical system 220 and the imaging optical system 240 are housed in an electron tube 204. The inside of the electron tube 204, including the sample chamber 202, is maintained in a vacuum state. The main body 200 is supported by a vibration isolation table 270.

[0017] In the main body 200, the irradiation optical system 220 focuses the electron beam to form an electron probe and deflects the electron beam. This allows the electron probe to scan the sample S. In the transmission electron microscope 2, a STEM image can be acquired by scanning the sample S with the electron probe and detecting electrons that have transmitted through the sample S with the detector 260. In the transmission electron microscope 2, the irradiation optical system 220 irradiates the sample S with a parallel electron beam, the imaging optical system 240 forms a TEM image using the electrons that have transmitted through the sample S, and the imaging device 250 can capture the TEM image.

[0018] The configuration of the main body 200 is not particularly limited, and may include, for example, various detectors, various spectroscopes, various manipulators, etc. For example, the main body 200 may include an X-ray detector that detects characteristic X-rays generated from the sample S by irradiating the sample S with an electron beam.

[0019] The main body 200 has a sample chamber 202 in which a sample S is placed. The sample S placed in the sample chamber 202 is supported by a sample holder 300. The sample holder 300 is inserted into an insertion opening of the holder support part 230. The sample holder 300 can be inserted into and removed from the insertion opening of the holder support part 230.

[0020] The control unit 400 controls each part of the transmission electron microscope 2. The control unit 400 includes, for example, a processor such as a CPU (Central Processing Unit) and a storage unit configured with RAM (Random Access Memory) and ROM (Read Only Memory). The storage unit stores programs and data for performing various controls. The functions of the control unit 400 can be realized by executing the programs with the processor. The control unit 400 may be realized, for example, by a general-purpose circuit such as a microcontroller or microprocessor that operates according to a program, or may be realized by a dedicated circuit such as an ASIC (Application Specific Integrated Circuit).

[0021] The vacuum pumping system 500 evacuates the electron gun chamber, which is the space housing the electron gun 210, the space inside the column 204 including the sample chamber 202, and the space where the imaging device 250 and the detector 260 are arranged. The vacuum pumping system 500 is also used for pre-evacuation when the sample holder 300 is introduced into the sample chamber 202. The vacuum pumping system 500 is controlled by the control unit 400. The computer functioning as the control unit 400 and the vacuum pumping system 500 are housed in the housing 10. It may be placed outside of 0.

[0022] 1.1.2. Housing FIG. 2 is a perspective view that schematically shows the housing 100. As shown in FIG. 2, the housing 100 has a rectangular parallelepiped shape. The housing 100 includes a plurality of metal plates. The metal plates are metal plates. The housing 100 covers the main body 200 with the plurality of metal plates. Therefore, the main body 200 cannot be seen from outside the housing 100. Note that the housing 100 may include a plurality of resin plates, and the main body 200 may be covered with the plurality of resin plates.

[0023] FIG. 3 is a front view schematically showing the housing 100. As shown in FIG.

[0024] As shown in Figures 2 and 3, a recess 110 is formed in the housing 100. The recess 110 is provided on a side surface 102 of the housing 100. The side surface 102 forms the front surface of the housing 100. An exchange port 120 is formed at the bottom of the recess 110. The exchange port 120 is an opening for the sample holder 300 to access the insertion port of the holder support part 230.

[0025] The housing 100 is equipped with an operation unit 130 that accepts user operations. The operation unit 130 is provided on a side surface 102 of the housing 100. That is, the operation unit 130 and the recess 110 are provided on the same side surface 102. When the operation unit 130 accepts a user operation, the control unit 400 executes processing in accordance with the user operation. The operation unit 130 is, for example, a touch panel.

[0026] 1.1.3. Vacuum pumping system FIG. 4 is a diagram showing an example of the configuration of the vacuum exhaust system 500.

[0027] As shown in FIG. 4, the vacuum exhaust system 500 includes a main exhaust pump 510 (an example of a first exhaust pump), a sub-exhaust pump 520 (an example of a second exhaust pump), a thermometer 522, a first valve 531, a second valve 532, a third valve 533, a fourth valve 534, a fifth valve 535, and a leak valve 536.

[0028] The holder support part 230 is provided with a pre-exhaust chamber 232. The pre-exhaust chamber 232 is connected to the sample chamber 202 via a gate valve 234. That is, the pre-exhaust chamber 232 and the sample chamber 202 are separated by the gate valve 234, and by opening the gate valve 234, the pre-exhaust chamber 232 and the sample chamber 202 communicate with each other.

[0029] The main exhaust pump 510 is connected to the main body 200 via a vibration damper. Therefore, even if the main exhaust pump 510 operates, the impact on the main body 200 is small. The main exhaust pump 510 has a first port 512, a second port 514, and an exhaust port 516. The first port 512 and the second port 514 are intake ports. The exhaust capacity when exhausting using the first port 512 is larger than the exhaust capacity when exhausting using the second port 514. In other words, the first port 512 is a main port, and the second port 514 is a sub-port.

[0030] The main exhaust pump 510 is, for example, a turbo molecular pump. A turbo molecular pump is a pump that compresses and exhausts gas by attaching a large number of metal blades obliquely to the periphery of a cylinder and rotating the cylinder at high speed. A large number of metal blades are arranged between the first port 512 and the exhaust port 516. The second port 514 is provided between the first port 512 and the exhaust port 516. In other words, the number of metal blades arranged between the first port 512 and the exhaust port 516 is equal to the number of metal blades arranged between the second port 514 and the exhaust port 516. Therefore, the exhaust capacity of the first port 512 is greater than the exhaust capacity of the second port 514.

[0031] The first port 512 is connected to the sample chamber 202. Here, the electron gun chamber, the space inside the microscope barrel 204 including the sample chamber 202, and the space in which the imaging device 250 and the detector 260 are arranged are all in communication with each other. That is, in the transmission electron microscope 2, no orifice or the like is arranged to maintain a pressure difference between these spaces, and these spaces form a single space with no pressure difference. Therefore, this single space can be evacuated from the first port 512.

[0032] The second port 514 is connected to the preliminary exhaust chamber 232. The exhaust port 516 is connected to the secondary exhaust pump 520.

[0033] The sub-exhaust pump 520 is housed in a console connected to the main body 200. This allows for a compact device in the transmission electron microscope 2. The transmission electron microscope 2 does not have a vibration isolation mechanism for preventing vibrations from the sub-exhaust pump 520 from being transmitted to the main body 200, so when the sub-exhaust pump 520 operates, it has a large effect on the main body 200.

[0034] The auxiliary exhaust pump 520 is, for example, a diaphragm pump. A diaphragm pump exhausts a fluid by changing the volume of a pump chamber separated by a diaphragm through the reciprocating motion of the diaphragm. The auxiliary exhaust pump 520 is connected to the preliminary exhaust chamber 232, the exhaust port 516, and the sample chamber 202.

[0035] The main exhaust pump 510 functions as a main pump for evacuating the sample chamber 202 and the preliminary exhaust chamber 232 to a target vacuum level and maintaining that level. The secondary exhaust pump 520 functions as a roughing pump for evacuating the sample chamber 202 and the preliminary exhaust chamber 232 to a vacuum level at which the main exhaust pump 510 can evacuate. The secondary exhaust pump 520 also functions as an auxiliary pump for maintaining the back pressure of the main exhaust pump 510 below a pressure at which the main exhaust pump 510 can function.

[0036] The thermometer 522 measures the temperature of the sub-exhaust pump 520. Information on the temperature of the sub-exhaust pump 520 measured by the thermometer 522 is sent to the control unit 400.

[0037] The first valve 531 is provided between the first port 512 and the sample chamber 202. That is, the first valve 531 is provided in the exhaust path that connects the first port 512 and the sample chamber 202.

[0038] The second valve 532 is provided between the second port 514 and the preliminary exhaust chamber 232. In other words, the second valve 532 is provided in the exhaust path that connects the second port 514 and the preliminary exhaust chamber 232.

[0039] The third valve 533 is provided between the sub-exhaust pump 520 and the preliminary exhaust chamber 232. That is, the third valve 533 is provided in the exhaust path that connects the sub-exhaust pump 520 and the preliminary exhaust chamber 232.

[0040] The fourth valve 534 is provided between the sub-exhaust pump 520 and the exhaust port 516 of the main exhaust pump 510. In other words, the fourth valve 534 is provided in the exhaust path that connects the sub-exhaust pump 520 and the exhaust port 516.

[0041] The fifth valve 535 is provided between the sub-exhaust pump 520 and the sample chamber 202. That is, the fifth valve 535 is provided in the exhaust path that connects the sub-exhaust pump 520 and the sample chamber 202.

[0042] The leak valve 536 is a valve for opening the sample chamber 202 to the atmosphere. As described above, in the transmission electron microscope 2, the space inside the electron gun chamber and the column 204 including the sample chamber 202 constitutes a single space, and therefore the leak valve 536 can open this single space to the atmosphere.

[0043] The control unit 400 controls the main exhaust pump 510, the sub-exhaust pump 520, the first valve 531, the second valve 532, the third valve 533, the fourth valve 534, the fifth valve 535, and the leak valve 536. The control unit 400 also controls the gate valve 234. The control unit 400 monitors the power consumption of the main exhaust pump 510. The control unit 400 also monitors the power consumption of the sub-exhaust pump 520.

[0044] 1.2. Operation 1.2.1. Operation of the vacuum pumping system when evacuating the sample chamber Fig. 5 is a flowchart showing an example of the control process of the vacuum exhaust system 500 when exhausting the sample chamber 202. In the initial state, the sample chamber 202 is open to the atmosphere, the leak valve 536 is open, and the gate valve 234 and the first to fifth valves are closed. The control process shown in Fig. 5 is a process for changing the sample chamber 202 from an open-to-the-atmosphere state to a vacuum state that allows the sample S to be introduced into the sample chamber 202.

[0045] The control unit 400 first rotates the main exhaust pump 510 at a steady rotation speed (step S100). The control unit 400 operates the auxiliary exhaust pump 520 to open the fourth valve 534 and cause the auxiliary exhaust pump 520 to exhaust air from the exhaust port 516 of the main exhaust pump 510. The control unit 400 operates the main exhaust pump 510 and waits until the rotation speed of the main exhaust pump 510 reaches a steady rotation speed.

[0046] After the rotation speed of the main exhaust pump 510 reaches a steady rotation speed, the control unit 400 closes the fourth valve 534 and opens the fifth valve 535 to cause the sub-exhaust pump 520 to evacuate the sample chamber 202 (step S102).

[0047] The control unit 400 determines whether the degree of vacuum in the sample chamber 202 has reached a level at which the main exhaust pump 510 can exhaust the sample chamber 202, based on the power and temperature of the auxiliary exhaust pump 520 (step S104). For example, if the degree of vacuum in the sample chamber 202 is low, exhausting the sample chamber 202 with the main exhaust pump 510 may place a load on the main exhaust pump 510, which may result in damage to the main exhaust pump 510. Therefore, in the processing of step S104, it is determined whether the degree of vacuum in the sample chamber 202 has reached a level at which the main exhaust pump 510 can exhaust the sample chamber 202.

[0048] Here, the power consumption of the auxiliary exhaust pump 520 corresponds to the degree of vacuum in the sample chamber 202, and the higher the degree of vacuum in the sample chamber 202, i.e., the lower the pressure in the sample chamber 202, the lower the power consumption of the auxiliary exhaust pump 520. Furthermore, the relationship between the degree of vacuum in the sample chamber 202 and the power consumption of the auxiliary exhaust pump 520 varies depending on the temperature of the auxiliary exhaust pump 520. For example, in a diaphragm pump, the lower the temperature, the harder the diaphragm becomes, so the lower the temperature, the greater the power consumption.

[0049] Therefore, the relationship between the power consumption of the auxiliary exhaust pump 520 and the degree of vacuum in the sample chamber 202 is checked in advance for each temperature of the auxiliary exhaust pump 520. This makes it possible to know the degree of vacuum in the sample chamber 202 from the temperature of the auxiliary exhaust pump 520 and the power consumption of the auxiliary exhaust pump 520.

[0050] For example, the storage unit of the control unit 400 stores a table showing the relationship between the power consumption of the sub-exhaust pump 520 and the degree of vacuum of the sample chamber 202 for each temperature of the sub-exhaust pump 520. The control unit 400 acquires information on the power consumption of the sub-exhaust pump 520 and the temperature of the sub-exhaust pump 520, and refers to the table stored in the storage unit to calculate the degree of vacuum of the sample chamber 202 from the acquired information on the power consumption and temperature. The control unit 400 determines the degree of vacuum in the sample chamber 202. The control unit 400 compares the determined degree of vacuum with the degree of vacuum that can be exhausted by the main exhaust pump 510, and determines whether the degree of vacuum in the sample chamber 202 has reached the degree of vacuum that can be exhausted by the main exhaust pump 510.

[0051] If the control unit 400 determines that the degree of vacuum in the sample chamber 202 has not reached a level at which the main exhaust pump 510 can exhaust the sample (No in step S104), it repeats the processing of step S104 until the degree of vacuum in the sample chamber 202 reaches a level at which the main exhaust pump 510 can exhaust the sample.

[0052] When the control unit 400 determines that the degree of vacuum in the sample chamber 202 has reached a level at which the main exhaust pump 510 can exhaust the sample (Yes in step S104), it closes the fifth valve 535 and opens the first valve 531 and the fourth valve 534 to have the main exhaust pump 510 exhaust the sample chamber 202 (step S106). As a result, the sample chamber 202 is evacuated by the main exhaust pump 510, and the exhaust port 516 of the main exhaust pump 510 is evacuated by the sub-exhaust pump 520. Therefore, the sample chamber 202 can be brought to a level at which the sample S can be introduced. After processing step S106, the control unit 400 ends the process.

[0053] In the process of step S104, the relationship between the power consumption of the auxiliary exhaust pump 520 and the degree of vacuum in the sample chamber 202 is expressed as a table, but the relationship between the power consumption of the auxiliary exhaust pump 520 and the degree of vacuum in the sample chamber 202 may also be expressed as a relational expression. That is, this relational expression may be stored in the memory unit of the control unit 400. This also applies to the processes described below.

[0054] Furthermore, in the processing of step S104, the degree of vacuum calculated from the power consumption of the auxiliary exhaust pump 520 is compared with the degree of vacuum in the sample chamber 202 that can be evacuated by the main exhaust pump 510. However, the power consumption of the auxiliary exhaust pump 520 may also be compared with the value of the power consumption of the auxiliary exhaust pump 520 that corresponds to the degree of vacuum in the sample chamber 202 that can be evacuated by the main exhaust pump 510.

[0055] Specifically, the power consumption value of the auxiliary exhaust pump 520 corresponding to the degree of vacuum in the sample chamber 202 that can be evacuated by the main exhaust pump 510 may be calculated in advance and stored in a storage unit. The control unit 400 may compare the power consumption value stored in the storage unit with the power consumption of the auxiliary exhaust pump 520 to determine whether the degree of vacuum in the sample chamber 202 has reached the degree of vacuum that can be evacuated by the main exhaust pump 510. This also applies to the processing described below.

[0056] Furthermore, in the above, in the process of step S104, the degree of vacuum is determined based on the power consumption of the sub-exhaust pump 520, but if the voltage consumption of the sub-exhaust pump 520 is constant, the degree of vacuum may be determined based on the current consumption of the sub-exhaust pump 520. Also, if the current consumption of the sub-exhaust pump 520 is constant, the degree of vacuum may be determined based on the voltage consumption of the sub-exhaust pump 520. In this way, "based on the power consumption of the sub-exhaust pump 520" includes the case where it is based on the current consumption of the sub-exhaust pump 520 and the case where it is based on the voltage consumption of the sub-exhaust pump 520. This also applies to the process described below.

[0057] 1.2.2. Operation of the vacuum pumping system when introducing a sample Fig. 6 is a flowchart showing an example of the control process of the vacuum exhaust system 500 when the sample S is introduced into the sample chamber 202. Here, a case will be described in which the control process shown in Fig. 6 is performed after the control process shown in Fig. 5 described above. That is, in the initial state, the first valve 531 is open and the sample chamber 202 is evacuated by the main exhaust pump 510, and the sample chamber 202 is at a vacuum level that allows the sample S to be introduced.

[0058] The control unit 400 determines whether the sample S supported by the sample holder 300 has been introduced into the pre-evacuation chamber 232 (step S200). It is determined that the sample S has been introduced into the preliminary exhaust chamber 232 when a sensor notifies the user that the sample S has been introduced into the preliminary exhaust chamber 232, or when the user inputs information that the sample S has been introduced into the preliminary exhaust chamber 232.

[0059] When the control unit 400 determines that the sample S has been introduced into the preliminary exhaust chamber 232 (Yes in step S200), it opens the third valve 533 and causes the auxiliary exhaust pump 520 to exhaust the preliminary exhaust chamber 232 (step S202).

[0060] Next, the control unit 400 determines whether the degree of vacuum in the preliminary exhaust chamber 232 has reached a first degree of vacuum based on the power and temperature of the auxiliary exhaust pump 520 (step S204). The first degree of vacuum is the degree of vacuum in the preliminary exhaust chamber 232 that can be exhausted by the main exhaust pump 510. For example, if the preliminary exhaust chamber 232 is evacuated by the main exhaust pump 510 in a low vacuum state where the degree of vacuum in the preliminary exhaust chamber 232 has not reached the first degree of vacuum, a load is placed on the main exhaust pump 510, which may cause damage to the main exhaust pump 510.

[0061] Here, the power consumption of the sub-exhaust pump 520 corresponds to the degree of vacuum in the preliminary exhaust chamber 232, and the higher the degree of vacuum in the preliminary exhaust chamber 232, the lower the power consumption of the sub-exhaust pump 520. Furthermore, the relationship between the degree of vacuum in the preliminary exhaust chamber 232 and the power consumption of the sub-exhaust pump 520 varies depending on the temperature of the sub-exhaust pump 520. Therefore, the relationship between the power consumption of the sub-exhaust pump 520 and the degree of vacuum in the preliminary exhaust chamber 232 is investigated in advance for each temperature of the sub-exhaust pump 520. This makes it possible to know the degree of vacuum in the preliminary exhaust chamber 232 from the temperature of the sub-exhaust pump 520 and the power consumption of the sub-exhaust pump 520.

[0062] For example, the memory unit of the control unit 400 stores a table indicating the relationship between the power consumption of the sub-exhaust pump 520 and the degree of vacuum in the preliminary exhaust chamber 232 for each temperature of the sub-exhaust pump 520. The control unit 400 acquires information on the power consumption and temperature of the sub-exhaust pump 520, and refers to the table stored in the memory unit to determine the degree of vacuum in the preliminary exhaust chamber 232 from the acquired information on power consumption and temperature. The control unit 400 compares the determined degree of vacuum with a first degree of vacuum to determine whether the degree of vacuum in the preliminary exhaust chamber 232 has reached the first degree of vacuum.

[0063] In addition, the control unit 400 may compare the power consumption of the auxiliary exhaust pump 520 with the value of the power consumption of the auxiliary exhaust pump 520 corresponding to the first degree of vacuum to determine whether the degree of vacuum in the preliminary exhaust chamber 232 has reached the first degree of vacuum.

[0064] If the control unit 400 determines that the degree of vacuum in the preliminary exhaust chamber 232 has not reached the first degree of vacuum (No in step S204), it repeats the processing of step S204 until the degree of vacuum in the preliminary exhaust chamber 232 reaches the first degree of vacuum.

[0065] When the control unit 400 determines that the degree of vacuum in the preliminary exhaust chamber 232 has reached the first degree of vacuum (Yes in step S204), it closes the third valve 533, opens the second valve 532, and causes the main exhaust pump 510 to exhaust the preliminary exhaust chamber 232 (step S206). At this time, the control unit 400 may operate the auxiliary exhaust pump 520, open the fourth valve 534, and cause the auxiliary exhaust pump 520 to exhaust the exhaust port 516 of the main exhaust pump 510.

[0066] Next, the control unit 400 determines whether the degree of vacuum in the preliminary exhaust chamber 232 has reached a second degree of vacuum based on the power consumption of the main exhaust pump 510 (step S208). The second degree of vacuum is a degree of vacuum at which the gate valve 234 can be opened. For example, the second degree of vacuum is a degree of vacuum at which no discharge occurs in the electron gun chamber even when the gate valve 234 is opened. In the transmission electron microscope 2, the sample chamber 202 and the electron gun chamber are connected, so if the degree of vacuum in the sample chamber 202 decreases, the degree of vacuum in the electron gun chamber also decreases, which may cause discharge. Therefore, even when the gate valve 234 is opened, no discharge occurs in the electron gun chamber. The value of the second vacuum degree is set so that no discharge occurs in the vacuum chamber.

[0067] Here, the power consumption of the main exhaust pump 510 corresponds to the degree of vacuum in the preliminary exhaust chamber 232, and the higher the degree of vacuum in the preliminary exhaust chamber 232, the lower the power consumption of the main exhaust pump 510. Therefore, the relationship between the power consumption of the main exhaust pump 510 and the degree of vacuum in the preliminary exhaust chamber 232 is examined in advance. This makes it possible to know the degree of vacuum in the preliminary exhaust chamber 232 from the power consumption of the main exhaust pump 510.

[0068] For example, the memory unit of the control unit 400 stores a table showing the relationship between the power consumption of the main exhaust pump 510 and the degree of vacuum in the preliminary exhaust chamber 232. The control unit 400 acquires information about the power consumption of the main exhaust pump 510, and refers to the table stored in the memory unit to determine the degree of vacuum in the preliminary exhaust chamber 232 from the acquired power consumption information. The control unit 400 compares the determined degree of vacuum with a second degree of vacuum to determine whether the degree of vacuum in the preliminary exhaust chamber 232 has reached the second degree of vacuum.

[0069] Although the temperature of the auxiliary exhaust pump 520 changes, the main exhaust pump 510 is always operating and its temperature is approximately constant. Furthermore, the power consumption of the main exhaust pump 510 is less dependent on temperature than the power consumption of the auxiliary exhaust pump 520. Therefore, here, the effect of the temperature of the main exhaust pump 510 is not taken into consideration when calculating the degree of vacuum of the preliminary exhaust chamber 232 from the power consumption of the main exhaust pump 510. As with the auxiliary exhaust pump 520, the effect of the temperature of the main exhaust pump 510 may be taken into consideration when calculating the degree of vacuum of the preliminary exhaust chamber 232 from the power consumption of the main exhaust pump 510.

[0070] If the control unit 400 determines that the degree of vacuum in the preliminary exhaust chamber 232 has not reached the second degree of vacuum (No in step S208), the control unit 400 repeats the processing of step S208 until the degree of vacuum in the preliminary exhaust chamber 232 reaches the second degree of vacuum.

[0071] When the control unit 400 determines that the degree of vacuum in the preliminary exhaust chamber 232 has reached the second degree of vacuum (Yes in step S208), it notifies the user that the sample S can be introduced into the sample chamber 202 (step S210). In the transmission electron microscope 2, for example, indirect lighting is provided at the bottom of the recess 110 in the housing 100, and the indirect lighting is turned on or blinks to notify the user that the sample S can now be introduced into the sample chamber 202. Note that the notification means is not particularly limited, and may be a change in the color of the light of the indirect lighting, a notification by sound such as a buzzer, or a message displayed on the display unit. After notifying the user (after step S210), the control unit 400 ends the process.

[0072] Upon receiving the notification, the user operates the sample holder 300 to introduce the sample S from the pre-exhaust chamber 232 into the sample chamber 202. Here, the holder support part 230 is provided with a guide groove for guiding the sample holder 300. The sample holder 300 is guided by the guide groove, so that the sample S can be moved from the pre-exhaust chamber 232 to the sample chamber 202. The guide groove is provided with a switch for opening the gate valve 234. Therefore, when the control part 400 detects that the switch has been pressed by the sample holder 300, it opens the gate valve 234. This allows the sample S to be introduced from the pre-exhaust chamber 232 into the sample chamber 202.

[0073] 1.2.3. Operation of the vacuum pumping system during microscopic examination In the transmission electron microscope 2, the auxiliary exhaust pump 520 is housed in a console connected to the main body 200. The transmission electron microscope 2 does not have a vibration isolation mechanism for preventing the vibration of the auxiliary exhaust pump 520 from being transmitted to the main body 200, so if the auxiliary exhaust pump 520 operates during microscopic observation, it will affect the observation. Therefore, during microscopic observation, i.e., when the sample S is irradiated with an electron beam, In this state, it is desirable not to operate the sub-exhaust pump 520.

[0074] The main exhaust pump 510 cannot operate independently, and the back pressure must be reduced by exhausting the exhaust port 516 with the auxiliary exhaust pump 520. If there is no gas release or leak from the space evacuated by the main exhaust pump 510, the back pressure of the main exhaust pump 510 will not increase even if the auxiliary exhaust pump 520 is stopped when the ultimate pressure of the system is reached.

[0075] However, because gas release and leakage cannot be reduced to zero, closing the fourth valve 534 increases the back pressure of the main exhaust pump 510. If this state is maintained, gas will begin to flow back before the back pressure of the main exhaust pump 510 reaches the critical back pressure, and the degree of vacuum in the sample chamber 202 will decrease. If the back pressure of the main exhaust pump 510 exceeds the critical back pressure, the main exhaust pump 510 will stop. To prevent this, it is necessary to reduce the back pressure of the main exhaust pump 510 before the back pressure of the main exhaust pump 510 reaches the critical back pressure.

[0076] If the time for which the auxiliary exhaust pump 520 is stopped can be made sufficiently longer than the time required for microscopic observation, there will be no disruption to the microscopic observation. To lengthen the time for which the auxiliary exhaust pump 520 is stopped, in the transmission electron microscope 2, the material, diameter, and length of the exhaust pipe connecting the exhaust port 516 and the fourth valve 534 are optimized. Specifically, the exhaust pipe is made of metal, and the diameter and length are adjusted to increase the volume of the space between the exhaust port 516 and the fourth valve 534. In the transmission electron microscope 2, the time for which the auxiliary exhaust pump 520 is stopped is, for example, about 30 hours.

[0077] 7 is a flowchart showing an example of the control process of the vacuum exhaust system 500 during microscopic examination. Here, a case will be described where the initial state during microscopic examination is a state in which the sample S is placed in the sample chamber 202, the first valve 531 is open and the sample chamber 202 is being evacuated by the main exhaust pump 510, and the fourth valve 534 is open and the exhaust port 516 of the main exhaust pump 510 is being evacuated by the sub-exhaust pump 520.

[0078] The control unit 400 determines whether or not the microscopy has started (step S400). The control unit 400 determines that the microscopy has started when the user opens a gun shutter (not shown). The gun shutter is a mechanism for switching the electron beam on and off, and is provided below the electron gun 210.

[0079] Next, the control unit 400 determines whether a certain time has passed since the start of the microscopic examination (step S402). The control unit 400 determines whether a certain time has passed since the gun shutter opened. If the control unit 400 determines that a certain time has passed since the start of the microscopic examination (Yes in step S402), it closes the fourth valve 534 and stops the sub-exhaust pump 520 (step S404).

[0080] Usually, observation is performed at low magnification immediately after the start of microscopy, so there is little effect even if the auxiliary exhaust pump 520 is operating. Therefore, the auxiliary exhaust pump 520 is stopped a certain time after the start of microscopy. After the auxiliary exhaust pump 520 is stopped, observation and photography at high magnification become possible.

[0081] After stopping the sub-exhaust pump 520, the control unit 400 determines whether the back pressure of the main exhaust pump 510 is greater than a first pressure based on the power consumption of the main exhaust pump 510 (step S406). The first pressure is set according to, for example, a critical back pressure. The first pressure is set to a pressure lower than the critical back pressure.

[0082] Here, the power consumption of the main exhaust pump 510 corresponds to the back pressure of the main exhaust pump 510, and the lower the back pressure of the main exhaust pump 510, the lower the power consumption of the main exhaust pump 510. In a servomolecular pump, as the back pressure increases, the power consumption increases in order to maintain a constant rotation speed. Therefore, the relationship between the power consumption of the main exhaust pump 510 and the back pressure is investigated in advance. This makes it possible to know the back pressure from the power consumption of the main exhaust pump 510.

[0083] For example, the memory unit of the control unit 400 stores information about the power consumption of the main exhaust pump 510 that corresponds to a first pressure. The control unit 400 acquires the information about the power consumption of the main exhaust pump 510, compares the acquired power consumption with the power consumption value stored in the memory unit, and determines whether the back pressure of the main exhaust pump 510 is greater than the first pressure. The control unit 400 determines that the back pressure of the main exhaust pump 510 has become greater than the first pressure when the power consumption of the main exhaust pump 510 becomes greater than the power consumption corresponding to the first pressure.

[0084] If the control unit 400 determines that the back pressure of the main exhaust pump 510 is equal to or lower than the first pressure (No in step S406), it repeats the process of step S406. If the control unit 400 determines that the back pressure of the main exhaust pump 510 is greater than the first pressure (Yes in step S406), it operates the auxiliary exhaust pump 520, opens the fourth valve 534, and causes the auxiliary exhaust pump 520 to exhaust air from the exhaust port 516 of the main exhaust pump 510 (step S408). The control unit 400 causes the auxiliary exhaust pump 520 to exhaust air from the exhaust port 516 for, for example, a preset time. This reduces the back pressure of the main exhaust pump 510. The control unit 400 causes the auxiliary exhaust pump 520 to exhaust air from the exhaust port 516 for, for example, about five minutes.

[0085] Next, the control unit 400 operates the sub-exhaust pump 520 for a preset time, and then determines whether the back pressure of the main exhaust pump 510 has become equal to or less than the second pressure based on the power consumption of the main exhaust pump 510 (step S410). The control unit 400 determines that the back pressure of the main exhaust pump 510 has become equal to or less than the second pressure when the power consumption of the main exhaust pump 510 has become equal to or less than the power consumption corresponding to the second pressure.

[0086] Here, the second pressure is set to, for example, a pressure lower than the first pressure. By setting the second pressure low, the time for which the sub-exhaust pump 520 is stopped can be extended. However, by setting the second pressure low, the operating time of the sub-exhaust pump 520 becomes longer. The process of step S410 is performed in the same manner as the process of step S406 described above, except that the criterion for determination is set to the second pressure.

[0087] If the control unit 400 determines that the back pressure of the main exhaust pump 510 is not equal to or less than the second pressure (No in step S410), it repeats the process of step S410. If the control unit 400 determines that the back pressure of the main exhaust pump 510 is equal to or less than the second pressure (Yes in step S410), it closes the fourth valve 534 and stops the operation of the sub-exhaust pump 520 (step S412).

[0088] Next, the control unit 400 determines whether or not the user has finished the speculum examination (step S414). The control unit 400 determines that the speculum examination has ended when the user closes the gun shutter (not shown).

[0089] If the control unit 400 determines that the microscopy has not ended (No in step S414), it returns to the process of step S406. The control unit 400 repeats the processes of steps S406, S408, S410, S412, and S414 until it determines that the microscopy has ended. This prevents the back pressure of the main exhaust pump from becoming greater than the first pressure, and makes it possible to maintain a constant degree of vacuum in the sample chamber 202. If the control unit 400 determines that the microscopy has ended (Yes in step S414), it ends the process.

[0090] As described above, in the transmission electron microscope 2, the main exhaust pump 510 can maintain the back pressure for about 30 hours even if the sub-exhaust pump 520 is stopped. If the time does not exceed 30 hours, the process of step S408 described above is not performed.

[0091] 1.2.4. Modification of the vacuum pumping system operation during microscopic examination FIG. 8 is a flowchart showing a modified example of the control process of the vacuum exhaust system 500 during microscopic examination.

[0092] In the example shown in FIG. 7, when the back pressure of the main exhaust pump 510 becomes greater than the first pressure (Yes in step S406), the auxiliary exhaust pump 520 is operated (step S408), and when the back pressure of the main exhaust pump 510 becomes equal to or less than the second pressure (Yes in step S410), the auxiliary exhaust pump 520 is stopped (step S412).

[0093] On the other hand, if the back pressure of the main exhaust pump 510 becomes greater than the first pressure (Yes in step S406), the auxiliary exhaust pump 520 may be operated (step S408), and after a preset exhaust time has elapsed (Yes in step S409), the auxiliary exhaust pump 520 may be stopped (step S412). By setting the set exhaust time to the time from when the auxiliary exhaust pump 520 starts exhausting the exhaust port 516 until the back pressure of the main exhaust pump 510 becomes equal to or less than the second pressure, it is possible to achieve the same effect as the example shown in FIG.

[0094] 1.2.5. Operation of the vacuum pumping system when not using a microscope When not being examined, that is, when the sample S is not being irradiated with an electron beam, the sub-exhaust pump 520 operates, and no problems arise even if the main body 200 vibrates. However, constantly operating the sub-exhaust pump 520 shortens the life of the sub-exhaust pump 520. Therefore, by operating the sub-exhaust pump 520 intermittently, the life of the sub-exhaust pump 520 can be extended.

[0095] 9 is a flowchart showing an example of the control process of the vacuum exhaust system 500 when no microscopic examination is being performed. Here, a case will be described in which the initial state when no microscopic examination is being performed is a state in which the sample chamber 202 is evacuated by the main exhaust pump 510.

[0096] The control unit 400 determines whether or not the state is a non-speculum examination state (step S500). The control unit 400 determines that the state is a non-speculum examination state when the user closes the gun shutter (not shown).

[0097] When the control unit 400 determines that the microscopy state is not being performed (Yes in step S500), the control unit 400 determines whether the back pressure of the main exhaust pump 510 is greater than the first pressure based on the power consumption of the main exhaust pump 510 (step S502). The process of step S502 is performed in the same manner as the process of step S406 shown in FIG.

[0098] If the control unit 400 determines that the back pressure of the main exhaust pump 510 is greater than the first pressure (No in step S502), it repeats the process of step S502. If the control unit 400 determines that the back pressure of the main exhaust pump 510 is greater than the first pressure (Yes in step S502), it operates the auxiliary exhaust pump 520 to open the fourth valve 534 and cause the auxiliary exhaust pump 520 to exhaust air from the exhaust port 516 of the main exhaust pump 510 (step S504). This allows the back pressure of the main exhaust pump 510 to be reduced.

[0099] Next, the control unit 400 determines whether the back pressure of the main exhaust pump 510 is equal to or lower than the second pressure based on the power consumption of the main exhaust pump 510 (step S506). The process of step S506 is performed in the same manner as the process of step S410 shown in FIG.

[0100] If the control unit 400 determines that the back pressure of the main exhaust pump 510 is not equal to or less than the second pressure (NO in step S506), the control unit 400 repeats the process of step S506. If the control unit 400 determines that the back pressure of the main exhaust pump 510 is equal to or less than the second pressure (YES in step S506), the control unit 400 The operation of the exhaust pump 520 is stopped (step S508).

[0101] In this way, the processes of steps S502, S504, S506, and S508 are performed in the same manner as the processes of steps S406, S408, S410, and S412 shown in FIG.

[0102] Next, the control unit 400 determines whether or not the speculum examination has started (step S510). The control unit 400 determines that the speculum examination has started when the user opens the gun shutter (not shown). If the control unit 400 determines that the speculum examination has not started (No in step S510), the control unit 400 returns to step S502. The control unit 400 repeats the processes of steps S502, S504, S506, S508, and S510 until it determines that the speculum examination has started. If the control unit 400 determines that the speculum examination has started (Yes in step S510), the control unit 400 ends the process.

[0103] The modified example of the process during speculum examination shown in FIG. 8 can also be applied to the process during non-speculum examination shown in FIG.

[0104] 1.2.6. Venting behavior Inside the column 204, there are units that are cooled by liquid nitrogen or Peltier elements. Examples of such units include a cooling unit for a CCD (charge coupled device) camera used as the imaging device 250, and a cold trap used as a device to prevent sample contamination. When venting the column 204 for maintenance of the device, these units may be damaged if they are cooled while the column 204 is vented.

[0105] In the transmission electron microscope 2, in order to prevent damage to the unit, the lock is released from the screen of an operating computer separate from the computer that constitutes the control unit 400, and then venting is performed using the vent operation button on the operation unit 130.

[0106] 10 and 11 are diagrams that schematically show a GUI (Graphical User Interface) screen 600 of the operating computer.

[0107] The GUI screen 600 has a box 602 for checking the status of the device. In the box 602, it is possible to check whether the column 204 can be vented. In the illustrated example, in the box 602, it is possible to check whether the accelerating voltage (HT) is applied, whether the sample holder 300 is inserted, and whether the sample contamination prevention device (ACD: Anti-contamination device) is operating.

[0108] The GUI screen 600 has an unlock button 604 for unlocking the lock, and a cancel button 606. For example, as shown in Fig. 10, when all items in the box 602 are OK, the unlock button 604 lights up. Pressing the unlock button 604 unlocks the lock, and the vent operation button on the touch panel that functions as the operation unit 130 becomes active for a certain period of time.

[0109] Also, for example, as shown in FIG. 11, if all items in the box 602 are not OK, the release button 604 goes out and only the cancel button 606 lights up.

[0110] When the vent operation button of the operation unit 130 is pressed, the control unit 400 closes the first valve 531, the second valve 532, the third valve 533, and the fifth valve 535, and opens the fourth valve 534. In addition, the control unit 400 operates the main exhaust pump 510 and the sub-exhaust pump 520. In this state, the lens barrel 204 is vented by opening the leak valve 536.

[0111] When the inside of the column 204 is evacuated from a vented state to a state in which the inside of the column 204 can be evacuated to a state in which the sample S can be introduced into the sample chamber 202, the control process of the vacuum exhaust system 500 shown in FIG. 5 described above may be executed.

[0112] Effects The transmission electron microscope 2 includes a sample chamber 202 in which a sample S is placed, a pre-exhaust chamber 232 connected to the sample chamber 202 via a gate valve 234, a main exhaust pump 510 having a first port 512, a second port 514, and an exhaust port 516, with the first port 512 connected to the sample chamber 202 and the second port 514 connected to the pre-exhaust chamber 232, and an auxiliary exhaust pump 520 connected to the preliminary exhaust chamber 232, the exhaust port 516, and the sample chamber 202. The transmission electron microscope 2 further includes a control unit 400 that controls the main exhaust pump 510 and the auxiliary exhaust pump 520.

[0113] In addition, when the sample S is introduced into the pre-exhaust chamber 232, the control unit 400 performs the following processes: evacuating the pre-exhaust chamber 232 with the auxiliary exhaust pump 520; determining whether the vacuum level in the pre-exhaust chamber 232 has reached a first vacuum level based on the power of the auxiliary exhaust pump 520; and evacuating the pre-exhaust chamber 232 with the main exhaust pump 510 when it is determined that the vacuum level in the pre-exhaust chamber 232 has reached the first vacuum level.

[0114] Therefore, in the transmission electron microscope 2, the preliminary exhaust chamber 232 can be evacuated using the main exhaust pump 510, and therefore, when the gate valve 234 is opened to introduce the sample S from the preliminary exhaust chamber 232 into the sample chamber 202, the decrease in the degree of vacuum in the sample chamber 202 can be reduced compared to, for example, when the preliminary exhaust chamber 232 is evacuated only by the auxiliary exhaust pump 520. Furthermore, in the transmission electron microscope 2, the degree of vacuum in the preliminary exhaust chamber 232 is determined from the power of the auxiliary exhaust pump 520, so a vacuum gauge for measuring the degree of vacuum in the preliminary exhaust chamber 232 is not required. Therefore, the number of parts in the transmission electron microscope 2 can be reduced.

[0115] Furthermore, in the transmission electron microscope 2, the inside of the microscope column 204 including the sample chamber 202 and the auxiliary exhaust chamber 232 can be evacuated using one main exhaust pump 510 and one auxiliary exhaust pump 520, so the vacuum exhaust system 500 can be realized with a simple configuration.

[0116] In the transmission electron microscope 2, the sample chamber 202 and the electron gun chamber are connected to each other. In the transmission electron microscope 2, the pre-exhaust chamber 232 can be evacuated using the main exhaust pump 510, and therefore, when the gate valve 234 is opened to introduce the sample S from the pre-exhaust chamber 232 into the sample chamber 202, a decrease in the degree of vacuum in the sample chamber 202 can be reduced. Therefore, in the transmission electron microscope 2, when the sample S is introduced into the sample chamber 202, the possibility of a decrease in the degree of vacuum in the electron gun chamber and an electric discharge occurring can be reduced. Therefore, in the transmission electron microscope 2, the sample S can be introduced into the sample chamber 202 from the pre-exhaust chamber 232 even when the electron gun 210 is generating an electron beam.

[0117] The transmission electron microscope 2 includes a thermometer 522 that measures the temperature of the auxiliary exhaust pump 520, and the control unit 400, in the process of determining whether the degree of vacuum in the preliminary exhaust chamber 232 has reached the first degree of vacuum, determines whether the degree of vacuum in the preliminary exhaust chamber 232 has reached the first degree of vacuum based on the power of the auxiliary exhaust pump 520 and the temperature of the auxiliary exhaust pump 520. Therefore, the transmission electron microscope 2 can accurately know the degree of vacuum in the preliminary exhaust chamber 232 even if the relationship between the degree of vacuum in the sample chamber 202 and the power consumption of the auxiliary exhaust pump 520 changes depending on the temperature of the auxiliary exhaust pump 520. Therefore, the transmission electron microscope 2 can accurately determine the timing to have the main exhaust pump 510 evacuate the preliminary exhaust chamber 232.

[0118] In the transmission electron microscope 2, the control unit 400, after causing the main exhaust pump 510 to evacuate the preliminary exhaust chamber 232, performs the following processes: determining whether the degree of vacuum in the preliminary exhaust chamber 232 has reached a second degree of vacuum based on the power of the main exhaust pump 510; and notifying the user that the sample S can be introduced into the sample chamber 202 when the degree of vacuum in the preliminary exhaust chamber 232 has reached the second degree of vacuum. Therefore, the transmission electron microscope 2 can know the timing to introduce the sample S from the preliminary exhaust chamber 232 into the sample chamber 202. Furthermore, because the degree of vacuum in the preliminary exhaust chamber 232 is determined from the power of the main exhaust pump 510, the transmission electron microscope 2 does not require a vacuum gauge to measure the degree of vacuum in the preliminary exhaust chamber 232. Therefore, the number of parts in the transmission electron microscope 2 can be reduced.

[0119] In the transmission electron microscope 2, the control unit 400 performs the following processes: causing the main exhaust pump 510 to evacuate the sample chamber 202; stopping the auxiliary exhaust pump 520; determining whether the back pressure of the main exhaust pump 510 is greater than a first pressure based on the power of the main exhaust pump 510; and causing the auxiliary exhaust pump 520 to evacuate the exhaust port 516 of the main exhaust pump 510 if it is determined that the back pressure of the main exhaust pump 510 is greater than the first pressure. Furthermore, the control unit 400 performs the following processes: determining whether the back pressure of the main exhaust pump 510 is equal to or less than a second pressure based on the power of the main exhaust pump 510; and stopping the auxiliary exhaust pump 520 if it is determined that the back pressure of the main exhaust pump 510 is equal to or less than the second pressure. In this way, in the transmission electron microscope 2, the auxiliary exhaust pump 520 is operated intermittently, thereby extending the life of the auxiliary exhaust pump 520. Furthermore, in the transmission electron microscope 2, the back pressure of the main exhaust pump 510 is determined from the power of the main exhaust pump 510, so there is no need for, for example, a vacuum gauge for measuring the back pressure of the main exhaust pump 510. Therefore, the number of parts in the transmission electron microscope 2 can be reduced.

[0120] The control method for the transmission electron microscope 2 includes the steps of causing the auxiliary exhaust pump 520 to evacuate the preliminary exhaust chamber 232 when the sample S is introduced into the preliminary exhaust chamber 232, determining whether the degree of vacuum in the preliminary exhaust chamber 232 has reached a first degree of vacuum based on the power of the auxiliary exhaust pump 520, and causing the main exhaust pump 510 to evacuate the preliminary exhaust chamber 232 when it is determined that the degree of vacuum in the preliminary exhaust chamber 232 has reached the first degree of vacuum. In this way, the control method for the transmission electron microscope 2 uses the main exhaust pump 510 to evacuate the preliminary exhaust chamber 232, and therefore can reduce a decrease in the degree of vacuum in the sample chamber 202 when the gate valve 234 is opened to introduce the sample S from the preliminary exhaust chamber 232 into the sample chamber 202.

[0121] 1.4. Variations FIG. 12 is a diagram showing a modified example of the configuration of the vacuum exhaust system 500 of the transmission electron microscope 2 according to the first embodiment.

[0122] In the first embodiment described above, the power consumption of the auxiliary exhaust pump 520 changes with a change in temperature, and therefore the relationship between the degree of vacuum in the sample chamber 202 and the power consumption of the auxiliary exhaust pump 520 changes depending on the temperature of the auxiliary exhaust pump 520. Similarly, the relationship between the degree of vacuum in the preliminary exhaust chamber 232 and the power consumption of the auxiliary exhaust pump 520 changes depending on the temperature of the auxiliary exhaust pump 520. For this reason, as shown in FIG. 4 , the transmission electron microscope 2 has a thermometer 522 for measuring the temperature of the auxiliary exhaust pump 520.

[0123] In contrast, in this modification, a pump whose power consumption does not change even when the temperature changes is used as the sub-exhaust pump 520. Therefore, in this modification, the relationship between the degree of vacuum in the sample chamber 202 and the power consumption of the sub-exhaust pump 520 does not change depending on the temperature of the sub-exhaust pump 520. Furthermore, the relationship between the degree of vacuum in the preliminary exhaust chamber 232 and the power consumption of the sub-exhaust pump 520 does not change depending on the temperature of the sub-exhaust pump 520. Therefore, as shown in FIG. 12 , the transmission electron microscope 2 does not have a thermometer for measuring the temperature of the sub-exhaust pump 520.

[0124] 5, it is determined whether the degree of vacuum in the sample chamber 202 has reached a degree of vacuum that can be exhausted by the main exhaust pump 510 based on the power consumption of the sub-exhaust pump 520, without considering the temperature of the sub-exhaust pump 520. Also, in the process of step S204 shown in FIG. 6, it is determined whether the degree of vacuum in the preliminary exhaust chamber 232 has reached a degree of vacuum (first degree of vacuum) that can be exhausted by the main exhaust pump 510, based on the power consumption of the sub-exhaust pump 520, without considering the temperature of the sub-exhaust pump 520.

[0125] 2. Second embodiment 2.1. Configuration of a transmission electron microscope Next, a transmission electron microscope according to a second embodiment will be described. The transmission electron microscope according to the second embodiment is similar to the transmission electron microscope 2 shown in Fig. 1 described above, and therefore a description thereof will be omitted.

[0126] 2.2. Operation 2.2.1. Operation of the vacuum pumping system when evacuating the sample chamber The control process of the vacuum exhaust system 500 when exhausting the sample chamber 202 is the same as the control process shown in FIG. 5 described above, and therefore a description thereof will be omitted.

[0127] 2.2.2. Operation of the vacuum pumping system when introducing a sample The control process of the vacuum exhaust system 500 when the sample S is introduced into the sample chamber 202 differs in step S204 from the control process shown in Fig. 6. Below, differences from the first embodiment will be described, and explanations of similarities will be omitted.

[0128] In the first embodiment described above, in the processing of step S204, the control unit 400 determines whether the degree of vacuum in the preliminary exhaust chamber 232 has reached the degree of vacuum (first vacuum) that can be exhausted by the main exhaust pump 510, based on the power of the auxiliary exhaust pump 520 and the temperature of the auxiliary exhaust pump 520.

[0129] In contrast to this, in the second embodiment, as will be described later in "2.3.4. Operation of Vacuum Exhaust System When Not Performing Examination," the temperature of the auxiliary exhaust pump 520 can be maintained within a temperature range that does not change the relationship between the degree of vacuum in the preliminary exhaust chamber 232 and the power consumption of the auxiliary exhaust pump 520. Therefore, in the processing of step S204, the control unit 400 determines whether the degree of vacuum in the preliminary exhaust chamber 232 has reached the first vacuum degree based on the power of the auxiliary exhaust pump 520, without taking into account the temperature of the auxiliary exhaust pump 520.

[0130] For example, the memory unit of the control unit 400 stores a table showing the relationship between the power consumption of the auxiliary exhaust pump 520 and the degree of vacuum in the preliminary exhaust chamber 232. The control unit 400 acquires information about the power consumption of the auxiliary exhaust pump 520, and, by referring to the table stored in the memory unit, calculates the degree of vacuum in the preliminary exhaust chamber 232 from the acquired power consumption information. The control unit 400 compares the calculated degree of vacuum with the degree of vacuum that can be exhausted by the main exhaust pump 510, and determines whether the degree of vacuum in the preliminary exhaust chamber 232 has reached the first degree of vacuum.

[0131] The memory unit of the control unit 400 may store a value of power consumption of the sub-exhaust pump 520 corresponding to the first degree of vacuum. In this case, the control unit 400 may compare the acquired power consumption information with the value of power consumption of the sub-exhaust pump 520 stored in the memory unit to determine whether the degree of vacuum in the preliminary exhaust chamber 232 has reached the first degree of vacuum. In other words, the control unit 400 determines that the degree of vacuum in the preliminary exhaust chamber 232 has reached the first degree of vacuum when the power consumption of the sub-exhaust pump 520 reaches the power consumption of the sub-exhaust pump 520 corresponding to the first degree of vacuum.

[0132] 2.2.3. Operation of the vacuum pumping system during microscopic examination The control process of the vacuum exhaust system 500 during microscopic examination is the same as the control process shown in FIG. 7, and therefore a description thereof will be omitted.

[0133] 2.2.4. Operation of the vacuum pumping system when not using a microscope The relationship between the degree of vacuum in the preliminary exhaust chamber 232 and the power consumption of the auxiliary exhaust pump 520 varies depending on the temperature of the auxiliary exhaust pump 520. Therefore, in the second embodiment, the auxiliary exhaust pump 520 is operated at predetermined time intervals to maintain the temperature of the auxiliary exhaust pump 520 within a temperature range in which the relationship between the degree of vacuum in the preliminary exhaust chamber 232 and the power consumption of the auxiliary exhaust pump 520 does not change. As a result, in the process of step S204, the control unit 400 can determine whether the degree of vacuum in the preliminary exhaust chamber 232 has reached the first vacuum degree based on the power of the auxiliary exhaust pump 520, without taking into account the temperature of the auxiliary exhaust pump 520.

[0134] Furthermore, by evacuating the exhaust port 516 of the main exhaust pump 510 at predetermined time intervals, it is possible to prevent the back pressure of the main exhaust pump 510 from reaching a critical back pressure when it is time to replace the sample S. In the transmission electron microscope 2, when the back pressure of the main exhaust pump 510 reaches a critical back pressure, the auxiliary exhaust pump 520 evacuates the exhaust port 516 of the main exhaust pump 510. Therefore, in this case, the sample S cannot be replaced until the back pressure of the main exhaust pump 510 falls below a threshold, resulting in a waiting time. By evacuating the exhaust port 516 of the main exhaust pump 510 at predetermined time intervals, it is possible to eliminate this waiting time.

[0135] 13 is a flowchart showing an example of the control process of the vacuum exhaust system 500 when microscopy is not being performed. Here, a case will be described where the initial state when microscopy is not being performed is a state in which the sample chamber 202 is exhausted by the main exhaust pump 510. Below, differences from the control process shown in FIG. 9 above will be explained, and explanation of similarities will be omitted.

[0136] The control unit 400 determines whether or not the specimen chamber 202 is in a non-examination state (step S600). If the control unit 400 determines that the specimen chamber 202 is in a non-examination state (Yes in step S600), the control unit 400 operates the auxiliary exhaust pump 520, opens the fourth valve 534, and causes the auxiliary exhaust pump 520 to exhaust air from the exhaust port 516 of the main exhaust pump 510 (step S602). As a result, the specimen chamber 202 is exhausted by the main exhaust pump 510, and the exhaust port 516 of the main exhaust pump 510 is exhausted by the auxiliary exhaust pump 520.

[0137] The control unit 400 determines whether or not a first time has elapsed since the sub-exhaust pump 520 was operated (step S604). If the control unit 400 determines that the first time has not elapsed (No in step S604), it repeats the process of step S604.

[0138] When the control unit 400 determines that the first time has elapsed since the sub-exhaust pump 520 was started to operate (Yes in step S604), the control unit 400 closes the fourth valve 534 to stop the sub-exhaust pump 520.

[0139] Next, the control unit 400 determines whether or not the speculum examination has started (step S608). If the control unit 400 determines that the speculum examination has started (Yes in step S608), the control unit 400 ends the process.

[0140] If the control unit 400 determines that the microscopy has not started (No in step S608), it determines whether or not a second time has elapsed since the auxiliary exhaust pump 520 was stopped (step S610). If the control unit 400 determines that the second time has not elapsed (No in step S610), it returns to the processing of step S608.

[0141] If the control unit 400 determines that the second time has elapsed (Yes in step S610), the process returns to step S602. That is, the control unit 400 operates the auxiliary exhaust pump 520, opens the fourth valve 534, and causes the auxiliary exhaust pump 520 to exhaust air from the exhaust port 516 of the main exhaust pump 510 (step S602).

[0142] The control unit 400 repeats the processes of steps S602, S604, S606, S608, and S610 until the speculum examination is started.

[0143] The second time period in step S610 is set to, for example, about 25 minutes. The first time period in step S604 is set to, for example, about 5 minutes. That is, the sub-exhaust pump 520 is stopped for 25 minutes and then operated for 5 minutes, and this is repeated. This makes it possible to maintain the temperature of the sub-exhaust pump 520 within a temperature range that does not change the relationship between the degree of vacuum in the preliminary exhaust chamber 232 and the power consumption of the sub-exhaust pump 520.

[0144] The time period during which the back pressure of the main exhaust pump 510 reaches the critical back pressure is longer than the time period during which the temperature of the auxiliary exhaust pump 520 can be maintained within a temperature range in which the relationship between the degree of vacuum in the preliminary exhaust chamber 232 and the power consumption of the auxiliary exhaust pump 520 does not change. For example, in the transmission electron microscope 2, the time period during which the back pressure of the main exhaust pump 510 reaches the critical back pressure is approximately 30 hours, as described above. Therefore, by setting the first and second times so that the temperature of the auxiliary exhaust pump 520 can be maintained within a temperature range in which the relationship between the degree of vacuum in the preliminary exhaust chamber 232 and the power consumption of the auxiliary exhaust pump 520 does not change, it is possible to prevent the back pressure of the main exhaust pump 510 from reaching the critical back pressure.

[0145] Effects In the transmission electron microscope 2 according to the second embodiment, the control unit 400, when an electron beam is irradiating the sample S, performs the following operations: causing the main exhaust pump 510 to evacuate the sample chamber 202; determining whether the back pressure of the main exhaust pump 510 is greater than a first pressure based on the power of the main exhaust pump 510; causing the auxiliary exhaust pump 520 to evacuate the exhaust port 516 if it is determined that the back pressure of the main exhaust pump 510 is greater than the first pressure; determining whether the back pressure of the main exhaust pump 510 is equal to or less than a second pressure based on the power of the main exhaust pump 510; and stopping the auxiliary exhaust pump 520 if it is determined that the back pressure of the main exhaust pump 510 is equal to or less than the second pressure. In this way, in the transmission electron microscope 2, the auxiliary exhaust pump 520 is operated intermittently, thereby extending the life of the auxiliary exhaust pump 520. Furthermore, in the transmission electron microscope 2, the back pressure of the main exhaust pump 510 is determined from the power of the main exhaust pump 510, so there is no need for, for example, a vacuum gauge for measuring the back pressure of the main exhaust pump 510. Therefore, the number of parts in the transmission electron microscope 2 can be reduced.

[0146] In the transmission electron microscope 2 according to the second embodiment, when the electron beam is not irradiated onto the sample S, the control unit 400 performs the following processes: evacuating the sample chamber 202 with the main exhaust pump 510; operating the auxiliary exhaust pump 520 for a first time to evacuate the exhaust port 516 with the auxiliary exhaust pump 520; and repeating the process of stopping the auxiliary exhaust pump 520 for a second time.

[0147] Therefore, in the transmission electron microscope 2 according to the second embodiment, when not performing an examination, the temperature of the auxiliary exhaust pump 520 can be maintained within a temperature range in which the relationship between the degree of vacuum in the preliminary exhaust chamber 232 and the power consumption of the auxiliary exhaust pump 520 does not change. Therefore, during preliminary exhaust when introducing the sample S from the preliminary exhaust chamber 232 into the sample chamber 202, the degree of vacuum in the preliminary exhaust chamber 232 can be known from the power consumption of the auxiliary exhaust pump 520. Furthermore, a thermometer for measuring the temperature of the auxiliary exhaust pump 520 is not required.

[0148] 3. Variations 3.1. First Variant 14 is a diagram showing a modified configuration of the vacuum exhaust system 500. As shown in FIG. 14, the transmission electron microscope 2 may have a vacuum gauge 540 for measuring the degree of vacuum in the preliminary exhaust chamber 232 and a vacuum gauge 542 for measuring the degree of vacuum in the sample chamber 202. The vacuum gauge 540 is disposed between the preliminary exhaust chamber 232 and the third valve 533. The vacuum gauge 540 can also measure the back pressure of the main exhaust pump 510. The vacuum gauge 542 is disposed between the sample chamber 202 and the fifth valve 535.

[0149] In the transmission electron microscope 2 equipped with the vacuum exhaust system 500 shown in Fig. 14, for example, in the process of step S104 in Fig. 5, information on the degree of vacuum in the sample chamber 202 may be acquired from the vacuum gauge 542. Also, in the process of steps S204 and S208 shown in Fig. 6, information on the degree of vacuum in the preliminary exhaust chamber 232 may be acquired from the vacuum gauge 540. Also, in the process of steps S406 and S410 shown in Fig. 7, the back pressure of the main exhaust pump 510 may be acquired from the vacuum gauge 540.

[0150] 3.2. Second Variant In the first and second embodiments described above, the main exhaust pump 510 is a turbomolecular pump, but the main exhaust pump 510 is not limited to a turbomolecular pump. For example, the main exhaust pump 510 may be an oil diffusion pump (DP: diffusion pump). Furthermore, in the first and second embodiments described above, the sub-exhaust pump 520 is a diaphragm pump, but the sub-exhaust pump 520 is not limited to a diaphragm pump. For example, the sub-exhaust pump 520 may be a mechanical booster pump, a roots pump, or a rotary pump.

[0151] 3.3. Third Variant For example, in the above-described first and second embodiments, the charged particle beam device according to the present invention is described as a transmission electron microscope, but the charged particle beam device according to the present invention is not limited to a transmission electron microscope and may be, for example, a scanning electron microscope or a focused ion beam device. In other words, the charged particle beam device according to the present invention may be any device that includes a charged particle source that generates a charged particle beam such as an electron beam or an ion beam and irradiates the charged particle beam onto a sample.

[0152] The above-described embodiment and modifications are merely examples, and the present invention is not limited to these. For example, the embodiments and modifications can be combined as appropriate.

[0153] The present invention is not limited to the above-described embodiments, and various modifications are possible. For example, the present invention includes configurations that are substantially identical to the configurations described in the embodiments. A substantially identical configuration means, for example, a configuration with the same function, method, and result, or a configuration with the same purpose and effect. The present invention also includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. The present invention also includes configurations that achieve the same effects or purposes as the configurations described in the embodiments. The present invention also includes configurations in which publicly known technology is added to the configurations described in the embodiments. [Explanation of symbols]

[0154] 2...transmission electron microscope, 100...casing, 102...side surface, 110...recess, 120...exchange port, 130...operation unit, 200...main body, 202...sample chamber, 204...optical tube, 210...electron gun, 220...irradiation optical system, 230...holder support unit, 232...pre-exhaust chamber, 234...gate valve, 240...imaging optical system, 250...imaging device, 260...detector, 270...vibration isolation table, 300...sample holder, 400...control unit, 500...vacuum exhaust system, 510...main exhaust pump, 512...first port, 514...second port, 516...exhaust port, 520...auxiliary exhaust pump, 522...thermometer, 531...first valve, 532...second valve, 533...third valve, 534...fourth valve, 535...fifth valve, 536...leak valve, 540...vacuum gauge, 542...vacuum gauge, 600...GUI screen, 602...box, 604...release button, 606...cancel button

Claims

1. A charged particle beam device that irradiates a sample with a charged particle beam, a sample chamber in which the sample is placed; a preliminary exhaust chamber connected to the sample chamber via a gate valve; a first exhaust pump having a first port, a second port, and an exhaust port, the first port being connected to the sample chamber and the second port being connected to the preliminary exhaust chamber; a second exhaust pump connected to the preliminary exhaust chamber, the exhaust port, and the sample chamber; a control unit that controls the first exhaust pump and the second exhaust pump; Including, When the sample is introduced into the pre-evacuation chamber, the control unit a process of evacuating the preliminary exhaust chamber with the second exhaust pump; a process of determining whether or not the degree of vacuum in the preliminary exhaust chamber has reached a first degree of vacuum based on the power of the second exhaust pump; a process of causing the first exhaust pump to evacuate the preliminary exhaust chamber when it is determined that the degree of vacuum in the preliminary exhaust chamber has reached the first degree of vacuum; A charged particle beam device that performs the following:

2. In claim 1, a thermometer for measuring the temperature of the second exhaust pump; In the process of determining whether the vacuum degree in the pre-exhaust chamber has reached the first vacuum degree, the control unit determines whether the vacuum degree in the pre-exhaust chamber has reached the first vacuum degree based on the power of the second exhaust pump and the temperature of the second exhaust pump.

3. In claim 1, The control unit a process of determining whether or not the degree of vacuum in the preliminary exhaust chamber has reached a second degree of vacuum based on the power of the first exhaust pump after the process of causing the first exhaust pump to exhaust the preliminary exhaust chamber; a process of notifying the user that the sample can be introduced into the sample chamber when the degree of vacuum in the pre-evacuation chamber reaches the second degree of vacuum; A charged particle beam device that performs the following:

4. In claim 1, The control unit a process of evacuating the sample chamber using the first exhaust pump; determining whether a back pressure of the first exhaust pump is greater than a first pressure based on the power of the first exhaust pump; a process of causing the second exhaust pump to exhaust the exhaust port when it is determined that the back pressure of the first exhaust pump is greater than the first pressure; determining whether a back pressure of the first exhaust pump is equal to or less than a second pressure based on the power of the first exhaust pump; a process of stopping the second exhaust pump when it is determined that the back pressure of the first exhaust pump is equal to or less than a second pressure; A charged particle beam device that performs the following:

5. In claim 1, When the sample is irradiated with a charged particle beam, the control unit a process of evacuating the sample chamber using the first exhaust pump; determining whether a back pressure of the first exhaust pump is greater than a first pressure based on the power of the first exhaust pump; a process of causing the second exhaust pump to exhaust the exhaust port when it is determined that the back pressure of the first exhaust pump is greater than the first pressure; determining whether a back pressure of the first exhaust pump is equal to or less than a second pressure based on the power of the first exhaust pump; a process of stopping the second exhaust pump when it is determined that the back pressure of the first exhaust pump is equal to or less than a second pressure; A charged particle beam device that performs the following:

6. In claim 5, When the sample is not irradiated with the charged particle beam, the control unit a process of evacuating the sample chamber using the first exhaust pump; a process of repeatedly operating the second exhaust pump for a first time period to exhaust the exhaust port with the second exhaust pump and a process of stopping the second exhaust pump for a second time period; A charged particle beam device that performs the following:

7. In any one of claims 1 to 6, a charged particle source that generates a charged particle beam; The sample chamber and a space accommodating the charged particle source are in communication with each other.

8. a sample chamber in which a sample is placed; a preliminary exhaust chamber connected to the sample chamber via a gate valve; a first exhaust pump having a first port, a second port, and an exhaust port, the first port being connected to the sample chamber and the second port being connected to the preliminary exhaust chamber; a second exhaust pump connected to the preliminary exhaust chamber, the exhaust port, and the sample chamber; A method for controlling a charged particle beam device, comprising: When the sample is introduced into the pre-evacuation chamber, causing the second exhaust pump to evacuate the pre-evacuation chamber; determining whether the degree of vacuum in the preliminary exhaust chamber has reached a first degree of vacuum based on the power of the second exhaust pump; when it is determined that the degree of vacuum in the preliminary exhaust chamber has reached the first degree of vacuum, causing the first exhaust pump to evacuate the preliminary exhaust chamber; A method for controlling a charged particle beam device, comprising:

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