Method for operating a particle beam system and particle beam system

Abstract

A method for operating a particle beam system having multiple apertures includes a measurement method and an aperture determination method. The measurement method includes inserting any desired aperture among the apertures such that the aperture's aperture provides an opening through which an intermediate vacuum space of the particle beam system is connected to a sample space of the particle beam system. The aperture determination method includes: evacuating the intermediate vacuum space using a turbomolecular pump of the particle beam system; repeatedly recording values ​​characterizing the operating current supplied to the turbomolecular pump; and determining the limiting pressure of the sample space during the measurement method based on the multiple recorded values ​​characterizing the operating current supplied to the turbomolecular pump.

Description

Technical Field

[0001] The present invention relates to a method for operating a particle beam system and a particle beam system. Background Technology

[0002] In particle beam systems (such as electron beam microscopy), a particle beam generated by a particle beam source is guided onto a sample for examination. To operate the particle beam source and to prevent contamination, the source is positioned in a source space where a high or ultra-high vacuum is generated. The gas pressure in the sample space, where the sample is located, continuously increases, thus maintaining a much higher gas pressure compared to the source space. One reason for this continuous increase in gas pressure in the sample space is, for example, the method of supplying process gases to the sample, which causes the sample to discharge, thereby preventing undesirable charging effects.

[0003] When the particle beam is directed onto the sample, the source space opens towards the sample space, allowing gas to flow from the sample space into the vacuum of the source space. Therefore, a stop is positioned in the opening of the sample space to reduce any gas flow from the sample space to the source space. However, because this stop also reduces the image field on the sample that can be captured by the particle beam, it can be replaced by the user of the particle beam system, allowing the user to select a larger image field or a higher process gas supply as needed.

[0004] Typically, in conventional methods after changing the aperture, the user must explicitly specify which aperture is positioned in the particle beam system so that the system can limit the gas pressure in the sample space to the value allowed by the inserted aperture. Accordingly, in conventional methods, the problem is that user errors during aperture replacement can lead to the following effects: excessive gas flowing from the sample space into the source space, contamination of the particle beam source, or impaired stable operation of the particle beam source. Summary of the Invention

[0005] The purpose of this invention is to solve the above-mentioned problems and to provide a simplified, safer, and risk-free method for operating particle beam systems.

[0006] The particle beam system used in the method described below includes: a particle beam source for generating a particle beam; a sample holder on which a sample intended to be irradiated by the particle beam can be arranged; a evacuable source space in which the particle beam source is arranged; an evacuable sample space in which the sample holder is arranged; and an evacuable intermediate vacuum space. The intermediate vacuum space is separated from the source space and connected to the source space via a first opening through which the particle beam passes in the measurement method. Furthermore, the intermediate vacuum space is separated from the sample space and connected to the sample space via a second opening through which the particle beam passes in the measurement method. The particle beam system also includes a plurality of apertures, each having an aperture, wherein the apertures of the different apertures have different cross-sectional areas and / or different lengths. Each aperture may have multiple apertures. The sum of the cross-sectional areas of one or more apertures in the different apertures may be the same or different.

[0007] It should be noted that the terms "connection" and "phase connection" here refer to the possibility of gas flowing through the connection. For example, a connection between vacuum spaces means that gas flows from one vacuum space to another. Specifically, if no gas or a very small amount of gas can flow into another vacuum space, then one vacuum space is disconnected from the other. If gas can flow from one vacuum space through an opening into another, then the two vacuum spaces are connected via the opening. Additionally, a pumpable space is a space where gas is removed, reducing the gas pressure within the space. Signal lines and current lines are referred to here as electrical connections.

[0008] The proposed method for solving the above-mentioned problems includes a measurement method and an aperture determination method. The measurement method includes inserting any desired aperture body such that the aperture body's orifice provides a second opening. The aperture determination method includes: evacuating an intermediate vacuum space using a turbomolecular pump; repeatedly recording values ​​of variables characterizing the operating current supplied to the turbomolecular pump; and determining the limiting pressure of the sample space during the measurement method based on multiple recorded values ​​of the variables characterizing the operating current supplied to the turbomolecular pump. According to some embodiments, the aperture determination method further includes evacuating the sample space until a predetermined low pressure is reached, then increasing the flow rate of the gas entering the sample space, and repeatedly recording values ​​of the gas pressure in the sample space and values ​​of variables characterizing the operating current supplied to the turbomolecular pump during the increase in flow rate, wherein the limiting pressure is also determined based on multiple values ​​of the gas pressure.

[0009] For example, a limiting pressure is specified for each aperture, and this limiting pressure can be defined if the type of aperture is known. If evacuation of the sample space stops and the gas pressure in the sample space increases simultaneously, more or less gas flows into the intermediate vacuum space, depending on the inserted aperture. Since the intermediate vacuum space is evacuated by the turbomolecular pump, the load on the turbomolecular pump also increases with the increase in the flow rate of gas entering the intermediate vacuum space. The increased load can be recorded by measuring the operating current of the turbomolecular pump. Other exemplary parameters depending on the load of the turbomolecular pump are the electrical power of the turbomolecular pump or the rotational frequency of the turbomolecular pump blades. For example, since the operating current of the turbomolecular pump increases when the cross-sectional area of ​​the inserted aperture's orifice is large, the inserted aperture can be determined based on this operating current, and thus the permissible limiting pressure of the inserted aperture can be determined. Therefore, even if the user of the particle beam system misjudges the type of inserted aperture, the limiting pressure of the inserted aperture can be correctly set, and contamination of the particle beam source can be prevented.

[0010] According to some embodiments, the measurement method further includes arranging a sample on a sample holder, guiding a particle beam onto the sample, and detecting a signal generated by the particle beam at the sample. The measurement method may also include: scanning the sample with the particle beam and repeatedly detecting the signal generated by the particle beam; generating a particle optical image based on the detected signal; and storing the generated particle optical image. Guiding the particle beam onto the sample includes performing measures such that the particle beam generated by the particle beam source is incident on the sample. For this purpose, guiding may include opening a valve to prevent mechanical obstruction of the particle beam, and operating a deflection and scanning system of the particle beam system to guide the particle beam from the particle beam source to the sample. According to some embodiments in which the particle beam system is used to record particle optical images, the above measures can be performed to achieve a predefined image quality and magnification.

[0011] According to some embodiments, the measurement method also includes evacuating the sample space. Specifically, when performing the above-described aperture determination method, the valve between the source space and the intermediate vacuum space can be closed to completely separate the source space from the intermediate vacuum space. This provides the advantage that a significant increase beyond the limit pressure can be achieved if the gas pressure in the sample space increases during the aperture determination method. Then, in order to guide the particle beam onto the sample in the measurement method, the valve must be reopened; therefore, the sample space is evacuated to the previously determined permissible pressure before opening the valve.

[0012] According to some embodiments, the measurement method further includes recording the gas pressure in the sample space and increasing the flow rate of the gas entering the sample space based on the recorded gas pressure and a determined limiting pressure. In the above-described variable pressure method, the supplied gas is set to, for example, a gas flow rate, and the flow of gas from the sample space to the intermediate vacuum space or source space depends on the gas pressure present in the sample space. Gas is indirectly and continuously removed from the sample space by the flow of gas from the sample space to the intermediate vacuum space and by evacuating the intermediate vacuum space with a turbomolecular pump, such that an equilibrium gas pressure exists in the sample space for the set flow rate of the gas entering the sample space. This gas pressure can be recorded, for example, by a pressure sensor at the sample space, thereby allowing the gas flow rate to be adjusted so that the gas pressure generated in the sample space does not exceed the limiting pressure. According to some embodiments, the measurement method further includes stopping the increase in gas flow and maintaining the gas flow rate once the limiting pressure is reached.

[0013] According to some embodiments, the aperture determination method includes evacuating the sample space until a predetermined low pressure is reached, then closing the outlet opening of the turbomolecular pump, supplying gas into the sample space to create a predetermined increased pressure in the sample space, and repeatedly recording values ​​of variables characterizing the operating current supplied to the turbomolecular pump during the gas supply process, wherein determining the ultimate pressure further includes calculating at least one difference between these recorded values, and determining the ultimate pressure based on the calculated at least one difference.

[0014] In other words, as an alternative to increasing the gas flow rate in the sample space, a constant gas pressure can be maintained in the sample space, and the outlet opening of the turbomolecular pump can be closed, thereby increasing the gas pressure at the outlet opening of the turbomolecular pump. Depending on the rate at which the gas then flows from the sample space into the intermediate vacuum space, the gas pressure at the outlet opening of the turbomolecular pump increases faster or slower. The gas pressure at the outlet opening of the turbomolecular pump also affects the load on the turbomolecular pump, thus the size and / or depth of the inserted aperture are reflected, for example, in the time-varying gradient of the operating current of the turbomolecular pump. Therefore, it is possible to determine which aperture is inserted into the particle beam system. Thus, even if the user of the particle beam system misjudges the type of inserted aperture, the limiting pressure of the inserted aperture can be correctly set, and contamination of the particle beam source can be prevented.

[0015] According to some embodiments, each aperture has an identifier capable of identifying the corresponding aperture, wherein determining the limiting pressure includes determining the identifier of the inserted aperture and determining the limiting pressure based on the determined identifier of the inserted aperture. For example, the identifier may indicate the diameter and / or length of the aperture's aperture. For example, the settings of the particle beam system may also be changed during the measurement method based on the identifier. One such setting is, for example, activating a dual deflector to generate a pivot point in the aperture's opening, around which the particle beam can tilt as it passes through the aperture's opening. Whether such a pivot point is intended to be generated, or to what extent the particle beam is intended to tilt around such a pivot point, may depend on the cross-sectional area of ​​the aperture's opening and / or the length of the aperture's opening, as these characteristics affect the scannable image field and can be used to expand the image field.

[0016] According to some embodiments, the measurement method further includes storing the determined identifier of the inserted aperture along with the particle optical image. If it is intended to reproduce the particle optical image after capture, the aperture can be reinserted into the particle beam system to reproduce the particle optical image, provided that the identifier of the aperture is stored along with the particle optical image.

[0017] According to some embodiments, the method further includes a calibration method. The calibration method includes inserting an aperture with a given identifier, evacuating the sample space using a turbomolecular pump until a predetermined low pressure is reached, then increasing the flow rate of the gas entering the sample space, repeatedly recording the values ​​of the gas pressure in the sample space and the values ​​of variables characterizing the operating current supplied to the turbomolecular pump during the increase in flow rate, and storing the recorded values ​​of the gas pressure in the sample space and the variables characterizing the operating current supplied to the turbomolecular pump together with the given identifier. In this case, the aperture determination method further includes comparing the recorded values ​​of the gas pressure in the sample space and the variables characterizing the operating current supplied to the turbomolecular pump recorded in the aperture determination method with the stored values, and determining the identifier of the inserted aperture in the aperture determination method includes comparing the values ​​recorded in the aperture determination method with the values ​​stored in the calibration method, and selecting identifiers stored together with those values ​​having the smallest deviation relative to the values ​​recorded in the aperture determination method, according to a predetermined deviation criterion.

[0018] For example, the calibration method can be performed by the user of the particle beam system so that the aperture determination method can be performed even for new apertures not included in the original set of apertures. The above calibration method relates to an embodiment of the method in which the flow rate of the gas entering the sample space is increased in the aperture determination method.

[0019] According to an alternative embodiment, the calibration method includes inserting an aperture with a given identifier, evacuating the sample space using a turbomolecular pump until a predetermined low pressure is reached, then closing the outlet opening of the turbomolecular pump, supplying gas into the sample space to create a predetermined increased pressure, repeatedly recording values ​​characterizing the operating current supplied to the turbomolecular pump during the gas supply process, and storing the recorded values ​​characterizing the operating current supplied to the turbomolecular pump along with the given identifier. In this case, the aperture determination method further includes comparing the values ​​characterizing the operating current supplied to the turbomolecular pump recorded in the aperture determination method with the stored values, and determining the identifier of the inserted aperture in the aperture determination method includes comparing the values ​​recorded in the aperture determination method with the values ​​stored in the calibration method, and selecting identifiers stored along with those values ​​having the smallest deviation relative to the values ​​recorded in the aperture determination method, according to a predetermined deviation criterion.

[0020] This calibration method relates to an embodiment of the method in which the outlet opening of the turbomolecular pump is closed and the gas pressure in the sample space is maintained at a small, constant value. It should be emphasized that the constant gas pressure in the sample space in the calibration method is the same as the constant gas pressure in the sample space in the aperture determination method.

[0021] According to some embodiments, the minimum deviation has a least squares value based on a predetermined deviation criterion.

[0022] According to some embodiments, the aperture determination method is performed each time after the aperture body is inserted and before the particle beam is guided.

[0023] According to a specific embodiment, a method for operating the aforementioned particle beam system includes: inserting any desired aperture among these apertures such that the aperture of the aperture provides a second opening; using a turbomolecular pump to evacuate an intermediate vacuum space; receiving a value of the flow rate of gas entering the sample space; increasing the flow rate of gas entering the sample space toward the received value of the flow rate of gas entering the sample space; repeatedly recording the value of a variable characterizing the operating current supplied to the turbomolecular pump; terminating the process of increasing the flow rate of gas entering the sample space if the value of the variable characterizing the operating current supplied to the turbomolecular pump reaches a predetermined limit value; and issuing a notification regarding the termination of the process of increasing the flow rate of gas entering the sample space.

[0024] This embodiment has the advantage that the method does not require an additional aperture determination method before setting the desired gas supply to the sample. Specifically, the user can set the desired gas supply value to the sample, thereby increasing the gas pressure in the sample space towards the set value, and stopping the increase in gas pressure if, for example, the operating current of the turbomolecular pump becomes excessive. If this is the case, the process of increasing the gas pressure in the sample space is stopped, and the user is notified that the set value is not permitted for the inserted aperture. Therefore, even if the user of the particle beam system misjudges the type of inserted aperture, the gas pressure in the sample space can be prevented from exceeding the limit pressure of the inserted aperture, thereby preventing contamination of the particle beam source and not impairing the stable operation of the particle beam source.

[0025] According to some embodiments, the flow rate of gas entering the sample space is gradually increased in predetermined steps towards the received value of the flow rate of gas entering the sample space.

[0026] According to some embodiments, the method further includes placing the sample on a sample holder before increasing the flow rate of the gas entering the sample space, guiding the particle beam onto the sample when the flow rate of the gas entering the sample space has been reached, and detecting the signal generated by the particle beam at the sample.

[0027] According to some embodiments, the method further includes defining the instantaneous flow rate of the gas entering the sample space as a limiting inflow rate when the process of terminating the increase in the gas flow rate into the sample space is terminated. Therefore, a limiting pressure in the sample space can also be determined, which can be taken into account for later inputs. For example, the method also includes receiving another value of the gas flow rate entering the sample space, and issuing a notification if the other received value of the gas flow rate entering the sample space exceeds the defined limiting inflow rate.

[0028] According to some embodiments, the predetermined low pressure is less than 10. -4 millibar.

[0029] According to a specific embodiment, the particle beam system includes a controller configured to cause the particle beam system to perform the method described above after inserting any desired aperture into the apertures such that the aperture of the aperture provides a second opening, excluding the insertion of the aperture. Attached Figure Description

[0030] The above embodiments will now be explained in more detail with reference to the accompanying drawings.

[0031] Figure 1 The illustration shows a first electron beam microscope suitable for performing the method of the present invention.

[0032] Figure 2A second electron beam microscope suitable for performing the method of the present invention is illustrated.

[0033] Figure 3 The diagram shows Figure 1 and Figure 2 The image shows a set of multiple apertures in an electron beam microscope, along with detailed illustrations of them.

[0034] Figure 4 The diagram shows... Figure 1 and Figure 2 The image shows a cross-sectional view of the aperture of an electron beam microscope.

[0035] Figure 5 The illustration shows a flowchart illustrating a method according to a first embodiment.

[0036] Figure 6 The illustration shows a flowchart illustrating a method according to a second embodiment.

[0037] Figure 7 The illustration shows a flowchart illustrating a method according to a third embodiment.

[0038] Figure 8 The illustration shows a graph illustrating the calibration data used in the method according to the first embodiment.

[0039] Figure 9 The illustration shows a graph illustrating the calibration data used in the method according to the second embodiment. Detailed Implementation

[0040] Figure 1 The figure illustrates an electron beam microscope 1, which includes a source space 3, a first intermediate vacuum space 5, a second intermediate vacuum space 7, and a sample space 9. An electron beam source 11 is arranged in the source space 3. The electron beam source 11 is electrically connected to a controller 15 via a signal line 13, so that the controller 15 can supply a potential to the electron beam source 11 to generate an electron beam 17.

[0041] Source space 3 is separated from first intermediate vacuum space 5 by aperture 19. Aperture 19 has an opening 21 through which electron beam 17 passes when guided onto sample 23. First intermediate vacuum space 5 is separated from second intermediate vacuum space 7 by protection valve 25 and aperture 27. Aperture 27 has an opening 29 through which electron beam 17 passes when guided onto sample 23. Protection valve 25 includes a sealing plate 31 and actuator 33. Actuator 33 is electrically connected to controller 15 via signal line 35. Alternatively or additionally, actuator 33 can be pneumatically controlled by controller 15. For this purpose, controller 15 can transmit an electrical signal to a dedicated pneumatic controller, which then pneumatically controls actuator 33. If actuator 33 is operated via signal line 35 through controller 15, the actuator moves the sealing plate 31 into or out of the beam path of electron beam 17, thereby completely disconnecting or connecting the first intermediate vacuum space 5 and the second intermediate vacuum space 7, respectively. If protection valve 25 is opened and electron beam 17 is guided onto sample 23, electron beam 17 passes through protection valve 25.

[0042] The electron beam microscope 1 also includes a condenser lens 37 and an objective lens 39. The condenser lens 37 includes a pole piece 41 with an opening 43 and a coil 45. The coil 45 is electrically connected to a controller 15 via a signal line 47. The controller 15 controls the condenser lens 37 by supplying current to the coil 45, which generates a magnetic field that enters the beam path of the electron beam 17 from the pole piece 41 at the opening 43 and provides a focusing effect on the electron beam 17. The electron beam 17 passes through the condenser lens 37 in the first intermediate vacuum space 5.

[0043] Objective lens 39 includes a pole piece 49 with an opening 51 and a coil 53. Coil 53 is electrically connected to controller 15 via signal line 55. Controller 15 controls objective lens 39 by supplying current to coil 53, which generates a magnetic field that enters the beam path of electron beam 17 from pole piece 49 at opening 51 and provides a focusing effect on electron beam 17. Electron beam 17 passes through objective lens 39 within the second intermediate vacuum space 7.

[0044] The second intermediate vacuum space 7 is separated from the sample space 9 by an aperture arrangement 57. The aperture arrangement 57 includes a mounting member 59 with an opening 61, and a replaceable aperture body 63 carried by the mounting member 59. The aperture body 63 has a hole 65, the cross-sectional area of ​​which differs from the cross-sectional area of ​​the opening 61 of the mounting member 59. The user of the electron beam microscope 1 removes the aperture body 63 using a guide mechanism 67 and inserts another aperture body into the mounting member 59 using the guide mechanism 67; the user can then replace the aperture body 63. The aperture body can remain elsewhere in the sample space 9, or it can be removed via a vacuum lock 69 using the guide mechanism 67. It should be noted that... Figure 1 The guide mechanism 67 is illustrated, but in some embodiments, it is removed from the sample space 9 or laterally pivoted relative to the image field of the electron beam microscope 1 during the guidance of the electron beam 17 onto the sample 23. Instead of or supplementing the described use of the guide mechanism 67 to replace the aperture, the user of the electron beam microscope 1 can also manually insert and remove the aperture from the aperture holder 59, provided that atmospheric pressure is present in the sample space 9 to allow it to be opened.

[0045] Electron beam 17 passes through opening 61 of mounting 59 and aperture 65 of aperture 63. Electron beam 17 is then incident on sample 23.

[0046] Sample 23 is mounted on sample holder 73 by means of sample guide 71. Sample guide 71 includes guide rod 75 and carrier 77. In this case, the user places sample 23 on carrier 77 outside sample space 9, and then brings sample 23 to position in sample holder 73 by moving guide rod 75 through lock 79. Guide rod 75 can be detached from carrier 77 and removed from sample space 9. Instead of or attached to lock 79, electron beam microscope 1 may have an openable door in sample space 9 through which sample 23 can be mounted on sample holder 73. For example, if lock 79 and door are provided in sample space 9, samples that are too large for lock 79 can enter sample space 9 through door.

[0047] The electron beam microscope 1 also includes an actuator 81 that allows the relative position of the sample holder 73 and the aperture arrangement 57 to be changed. For this purpose, the actuator 81 is electrically connected to the controller 15 via a signal line 83.

[0048] The electron beam microscope 1 also includes a deflection arrangement 85. Figure 1 In this design, the deflection arrangement 85 is shown as an electrode pair, but it can also be implemented using an electromagnetic coil. The deflection arrangement 85 is electrically connected to the controller 15 via signal line 87. Therefore, the controller 15 can supply a potential to the deflection arrangement 85, causing it to generate an electric field in the beam path of the electron beam 17, thus deflecting the electron beam 17. This allows the electron beam 17 to be directed to different points on the sample 23.

[0049] When the electron beam 17 is incident on the sample 23, various signals are generated at the sample 23, such as secondary electrons and backscattered electrons. The electron beam microscope 1 also includes a detector 89 arranged in the sample space 9, which can record these signals and generate corresponding electrical signals. The electrical signals generated by the detector 89 are forwarded to the controller 15 via the signal line 91.

[0050] In order to capture particle optical images using electron beam microscope 1, controller 15 sequentially supplies different potentials to deflection arrangement 85, thereby guiding the electron beam to different incident positions on sample 23, and the controller stores the signal generated by detector 89 together with the incident positions on sample 23. This process is also referred to below as scanning of sample 23.

[0051] During operation of the electron beam microscope 1, vacuums of different qualities are generated in the source space 3, the first intermediate vacuum space 5, the second intermediate vacuum space 7, and the sample space 9. A high vacuum is generated in the source space 3, while a significantly poorer vacuum is maintained in the sample space 9. To generate vacuums in the source space 3, the first intermediate vacuum space 5, the second intermediate vacuum space 7, and the sample space 9, the electron beam microscope 1 also includes a pump system 93. The pump system 93 includes a forepump 95, a turbomolecular pump 97, a first ion uptake pump 99, and a second ion uptake pump 101. The forepump 95, for example, can reach a capacity of 10... -2 A positive displacement pump with a forestage vacuum of millibars. The turbomolecular pump 97 operates only after at least a forestage vacuum has been achieved; otherwise, the turbomolecular pump 97 may be damaged. The turbomolecular pump 97 reaches 10... -5 A vacuum of millibars. The first ion suction pump 99 and the second ion suction pump 101 require a vacuum generated by the turbomolecular pump 97 as a prerequisite and achieve a vacuum of 10. -6 millibars to 10 -10 High vacuum of millibars.

[0052] Since the foreboard pump 95 must first generate a foreboard vacuum in the source space 3, the first intermediate vacuum space 5, the second intermediate vacuum space 7, and the sample space 9, the foreboard pump 95 is connected to the sample space 9 via the foreboard pump line 103, the transition line 105, and the sample space line 107, allowing the foreboard pump 95 to evacuate the sample space 9. Furthermore, the foreboard pump 95 is connected to the second intermediate vacuum space 7 via the foreboard pump line 103, the transition line 105, the sample space line 107, and the turbopump line 109, allowing the foreboard pump 95 to evacuate the second intermediate vacuum space 7. Additionally, the foreboard pump 95 is connected to the source space 3 and the first intermediate vacuum space 5 via the foreboard pump line 103, the transition line 105, the sample space line 107, the turbopump line 109, and via the ion extraction pump line 111 and the ion extraction pump line 113, respectively, to enable evacuation of the source space and the first intermediate vacuum space. The backing pump 95 includes an outlet 114 that discharges the gas extracted from the vacuum space to the outside. The operation of the backing pump 95 is controlled by the controller 15 via signal line 116.

[0053] A separation valve 115 is provided in the transition line 105, by means of which the forepump 95 and forepump line 103 can be separated from the sample space line 107, and thus from all vacuum spaces. The separation valve 115 is electrically connected to the controller 15 via signal line 117, allowing the controller 15 to separate the forepump 95 from the vacuum space. In the electron beam microscope 1, the transition line 105 and valve 115 are unnecessary because a vacuum can also be generated by the forepump 95 through outlet 131 and the closed turbomolecular pump 97. Furthermore, the forepump line 103 is provided with a quiescent mode valve 119 electrically connected to the controller 15 via signal line 118, a buffer volume 121, and a separation valve 123 electrically connected to the controller 15 via signal line 122. The quiescent mode valve 119 and buffer volume 121 are used to temporarily shut down the forepump 95 to reduce vibration and noise. Separation valve 123 is closed via signal line 122 through controller 15 to protect turbomolecular pump 97 before the forestage vacuum is reached.

[0054] The turbomolecular pump 97 includes a rotor 125, a stator 127, vanes 129, and an outlet 131. The stator 127 is electrically connected to a controller 15 via a signal line 133. To operate the turbomolecular pump 97, the controller 15 supplies current to the stator 127 via the signal line 133, thereby causing the rotor 125 to rotate together with the vanes 129. The vanes 129 accelerate gas particles toward the outlet 131 by colliding with them. A current sensor 135 is arranged in the signal line 133 for recording the current supplied to the stator 127. Although the stator 127 is illustrated here without vanes, it should be noted that the stator 127 may also have vanes, for example, arranged between the multiple pairs of vanes 129 shown.

[0055] Turbomolecular pump 97 is connected to the second intermediate vacuum space 7 via turbopump line 109, to sample space 9 via turbopump line 109 and sample space line 107, and to source space 3 and first intermediate vacuum space 5 via turbopump line 109 and ion absorption pump lines 111 and 113 respectively. Furthermore, a separation valve 137 can be provided in turbopump line 109, which is electrically connected to controller 15 via signal line 139. Thus, for example, when the pre-stage pump 95 generates a forestage vacuum in the vacuum space via transition line 105, controller 15 can close separation valve 137.

[0056] The sample space line 107 also includes a separation valve 141, which is electrically connected to the controller 15 via a signal line 143. The separation valve 141 can be closed by the controller 15 to isolate the sample space line 107 from the turbopump line 109. For example, during a measurement method, when gas is supplied to the transition line 105 via the leak valve 151, the separation valve 141 closes to increase the gas pressure throughout the sample space 9. Thus, the separation valve 141 can be closed as needed to prevent a decrease in the gas pressure in the sample space 9 due to the operation of the turbomolecular pump 97.

[0057] A venting device 145 with a valve 147 is also provided on the sample space line 107. The valve 147 can be controlled by the controller 15 via the signal line 149. If the valve 147 is open, the venting device 145 connects the interior of the electron beam microscope 1 to the outside air, so that the electron beam microscope 1 is filled with air. This operation can be performed, for example, if damage to the electron beam microscope 1 is detected, if the user arranges a new sample 23 in the sample space 9 through the aforementioned alternative or additional door at the sample space 9, or if the electron beam microscope 1 is shut down for maintenance.

[0058] A leak valve 151 is provided on the transition line 105, and the leak valve can be controlled by a controller 15 via a signal line 153. The controller 15 can set the flow rate of the process gas at the leak valve 151, which flows into the transition line from the supply container 155 or from ambient air. The transition line 105 also has a pressure sensor 157, which records the gas pressure present in the transition line 105 and thus in the sample space 9, and generates a signal that is transmitted to the controller 15 via a signal line 159.

[0059] Ion pump lines 111 and 113 each have an ion pump 99 and an ion pump 101, respectively, as well as separation valves 161 and 163. Separation valve 161 can be controlled by controller 15 via signal line 165. Controller 167 communicates with controller 15 via signal line 169. Separation valve 163 can be controlled by controller 15 via signal line 171. Controller 167 controls the operation of ion pumps 99 and 101. If a vacuum that can be generated by turbomolecular pump 97 is reached in source space 3 and first intermediate vacuum space 5, controller 15 closes valves 161 and 163, and controller 167 supplies high voltage to ion pumps 99 and 101 via signal lines 173 and 175 to generate a high vacuum in source space 3 and first intermediate vacuum space 5. Controllers 15 and 167 can also be designed as a shared controller for controlling both valves 161 and 163, as well as supplying high voltage. Control of the corresponding components of the electron beam microscope 1 can be divided between controllers 15 and 167 in any desired manner.

[0060] For example, Figure 1 The valves 115, 119, 123, 137, 141, 147, 151, 161, and 163 shown may be solenoid valves. Valve 115, 119, 123, 137, 141, 147, 151, 161, and 163 may also be other valves, as long as they can be controlled by controller 15 and controller 167.

[0061] Figure 2 A second electron beam microscope 1' suitable for performing the method of the present invention is illustrated. Figure 2 In the diagram, the components and functional settings are indicated by corresponding reference numerals. For Figure 2 The accompanying figure labels and Figure 1 The same reference numerals are used for the same parts and functions as those in the accompanying drawings, and refer to the description of the parts or functions above.

[0062] Figure 2 The electron beam microscope 1' shown is Figure 1The difference in the electron beam microscope 1 shown is that the process gas flow is not supplied to the transition line 105, but is supplied directly to the sample 23 via a needle 177. The needle 177 is connected to the supply container 155 via a gas supply line 179 and a leak valve 151, allowing the process gas to be supplied directly to the sample 23 from the supply container 155 or ambient air. In the electron beam microscope 1', a pressure sensor 181 is mounted on the sample holder 73, which is electrically connected to the controller 15 via a signal line 183. This arrangement of the pressure sensor 181 has the advantage that the pressure near the needle 177 is recorded and is not distorted by a large distance relative to the local supply point of the process gas. It should also be noted that, in the case of localized supply of process gas via the needle 177, the separation valve 141 can be opened during the measurement method.

[0063] It should be noted that particle beam systems are not limited to electron beam microscopes. For example, a particle beam system can also be an ion beam system that generates a beam of particles composed of ionized atoms. Particle beam systems can also be integrated into larger systems, such as FIB-SEMs that simultaneously generate ion beams and electron beams.

[0064] Figure 3 The diagram shows... Figure 1 and Figure 2 The electron beam microscopes 1 and 1' shown here comprise a group of more than 185 apertures 63. Each aperture 63 has a circular aperture 65, and the circular apertures of different apertures 63 have different diameters. The apertures 63 are also designated by the letters A to F for easy identification.

[0065] For example, if the user of the electron beam microscope 1 selects an aperture F with a diameter of 0.2 mm, the user can insert the aperture into the aperture arrangement 57 of the electron beam microscope 1 via the guide mechanism 67 or manually. Figure 3 As indicated by arrow 187. The aperture 63 and mounting 58 can also be implemented as a single component. The mounting 59 can be screwed, clamped, or otherwise secured. The mounting 59 can be secured to the inside or outside of the pole shoe 49.

[0066] Figure 4 The diagram shows... Figure 1 and Figure 2The diagram shows a cross-sectional view of the aperture 63 of electron beam microscopes 1 and 1'. The aperture 63 includes an outer portion 189 for fixing the aperture 63. Additionally, the aperture 63 includes a tapered portion 191 defining an opening 65 of the aperture 63. The size of the opening 65 of the aperture 63 is indicated by arrows 193 and 195. In this case, arrow 195 indicates the diameter of the opening 65 of the aperture 63; specifically, the diameter is defined as the distance between arrows 195. Arrow 193 indicates the length of the opening 65 of the aperture 63. Figure 4 In the case shown, the length of the opening 65 corresponds to the thickness of the tapered portion 191.

[0067] The proposed methods according to different embodiments are described in detail below. Figure 5 The figure illustrates a flowchart of a method according to a first embodiment. The method according to the first embodiment includes steps S1 to S17. The method further includes an aperture determination method and a measurement method, wherein the aperture determination method includes steps S2 to S9, and the measurement method includes steps S1 and S10 to S17.

[0068] First, such as Figure 3 As shown, the user of the electron beam microscope 1 selects an aperture 63 from group 185 and inserts the selected aperture 63 into the aperture arrangement 57 in step S1. The user does not need to insert the aperture 63 into the aperture arrangement 57. If the user does not insert the aperture 63 into the aperture arrangement 57, the opening 61 acts as the aperture.

[0069] Then, the user, for example, uses the software of the electron beam microscope 1 to begin the aperture determination method. In steps S2 and S3, the controller 15 begins evacuating the sample space 9 and the second intermediate vacuum space 7. In one case, where the turbomolecular pump 97 continues to operate when the aperture body 63 is inserted, the separation valve 137 is closed (for this reason). The controller 15 begins to close the separation valve 123, open the static mode valve 119, and the separation valves 115 and 141, and operates the foreboard pump 95. For example, if the pressure sensor 157 records a pressure corresponding to the foreboard vacuum, the controller 15 closes the separation valve 115 and opens the separation valves 123 and 137. In another case, where the turbomolecular pump 97 does not operate when the aperture body 63 is inserted, the controller 15 first begins to operate the foreboard pump 95 with valves 119, 123, 137, and 141 open. The separation valve 115 can be closed or open. Afterward, the controller 15 closes the separation valve 115 and operates the turbomolecular pump 97.

[0070] Then, controller 15 operates turbomolecular pump 97 to evacuate sample space 9 and second intermediate vacuum space 7 with separation valve 141 open. If pressure sensor 157 records a predetermined low gas pressure, controller 15 closes separation valve 141. Additionally, controller 15 operates actuator 33 to close protection valve 25, and then proceeds to step S4.

[0071] In step S4, the controller 15 gradually increases the opening of the leakage valve 151, thereby gradually increasing the flow rate of the process gas entering the sample space. When the flow rate of the process gas entering the sample space is increased in step S4, in step S5, the controller 15 records the operating current supplied to the turbomolecular pump 97 through the current sensor 135, and also records the gas pressure in the sample space 9 through the pressure sensor 157.

[0072] In step S6, the controller 15 compares the operating current of the turbomolecular pump 97 with the change in gas pressure with predetermined calibration data. Figure 8 An example of such calibration data is illustrated in the figure below, and will be described later. For example, controller 15 can determine the gas pressure in sample space 9 at which the operating current of turbomolecular pump 97 begins to increase, and can compare that gas pressure with a predetermined value. For example, a comparison can also be performed such that controller 15 calculates for which aperture 63 has a least-squares value relative to the recorded pressure and the recorded operating current of turbomolecular pump 97.

[0073] In step S7, following the example above, the controller 15 selects an aperture 63 for which the calibration data has a least-squares value relative to the recorded pressure and the recorded operating current of the turbomolecular pump 97. Since the corresponding identifier of the aperture 63 is also stored in the calibration data, the controller selects the corresponding identifier of the selected aperture 63 and the settings of the electron beam microscope 1 associated with that identifier, particularly the associated limit pressure.

[0074] In step S8, the controller 15 then reads the determined limit pressure of the inserted aperture 63 and sets it as the limit pressure of the sample space 9 on the electron beam microscope 1. The controller 15 then proceeds to step S9. In step S9, the controller 15 displays a slider in the software of the electron beam microscope 1, which allows the user to set a desired gas pressure in the sample space 9, which will be used to prevent charging of the sample 23. The slider is limited to the limit pressure, so the user cannot set a value exceeding the limit pressure. Alternatively, the software may, for example, allow the user to set a value exceeding the limit pressure, and verify in step S12 (described later) whether the pressure desired by the user exceeds the limit pressure.

[0075] If sample 23 has not previously been mounted on sample holder 73 (e.g., through the aforementioned door at sample space 9), and if atmospheric pressure is present in sample space 9, in step S10, the user unlocks lock 79 and inserts sample 23 into sample space 9, then the user mounts the sample on sample holder 73. Subsequently, in step S11, controller 15 first opens separation valve 141 to evacuate sample space 9 again using turbomolecular pump 97. This is advantageous because the gas pressure in sample space prior to step S10 may be higher than the ultimate pressure due to the gradual increase in gas pressure during step S4.

[0076] In step S12, the user inputs a desired target gas pressure for the sample space 9 in the software of the electron beam microscope 1. This desired target gas pressure will be used to prevent the sample 23 from being charged. The set target gas pressure is then received by the controller 15. If the slider is limited to the limit pressure in step S9, the received target gas pressure is less than or equal to the limit pressure, and the controller 15 continues to step S13. However, if the software still allows any target gas pressure to be input, the input target gas pressure may be higher than the limit pressure. In this case, in step S12, the controller 15 verifies whether the received target gas pressure is greater than the limit pressure. If the target gas pressure is less than or equal to the limit pressure, the controller 15 continues to step S13. If the target gas pressure is greater than the limit pressure, the controller 15 may issue a warning to the user and define the limit pressure as the target gas pressure.

[0077] It should be noted that steps S10 to S12 can be performed in any desired order. Specifically, the user can first set the target gas pressure in the software of the electron beam microscope 1, and then arrange the sample 23 in the sample space 9. Alternatively, the sample space 9 can be evacuated before the sample 23 is arranged in it; specifically, during the arrangement of the sample 23, the lock 79 adequately protects the vacuum in the sample space from external gas supply. Furthermore, the user can also mount the sample 23 on the sample holder 73 before performing the aperture determination method, for example, when manually inserting the aperture body 63 as described above.

[0078] In step S13, controller 15 closes separation valve 141 and gradually opens leak valve 151 until the gas pressure recorded by pressure sensor 157 has reached the target gas pressure. Controller 15 also operates actuator 33 to open protection valve 25 so that electron beam 17 can enter sample space 9. Then, in steps S14 to S16, controller 15 captures particle optical images. For this purpose, in step S14, controller 15 sequentially supplies different potentials to deflection arrangement 85 to scan sample 23 with electron beam 17. If controller 15 has read the settings of electron beam microscope 1 that correspond to the aperture marking in step S7, these settings are used to capture particle optical images. For example, to reduce the limitation of the image field when the opening 65 of aperture body 63 is small, a pivot point can be generated in the opening 65 of aperture body 63 by means of dual deflectors so that electron beam 17 tilts as it passes through opening 65, thus scanning a larger image field. Furthermore, in step S15, for each incident point of the electron beam 17 on the sample 23, the detector 89 detects a signal, such as secondary electrons emitted by the sample 23 when the electron beam 17 is incident. By assigning the incident position on the sample 23 to the recorded signal, in step S16, the controller 15 generates a particle optical image, and then in step S17, the particle optical image is stored together with the identifier of the aperture 63. During the capture of the particle optical image, the gas flow rate is adjusted so that the pressure present in the sample space 9 remains constant to avoid changes in the brightness of the particle optical image.

[0079] Figure 6 The figure illustrates a flowchart of a method according to a second embodiment. The method according to the second embodiment includes the same steps S1 to S3 and S7 to S17 as the method according to the first embodiment, and further includes steps S4' to S6'. Descriptions of steps S1 to S3 and S7 to S17 as the method according to the first embodiment are omitted below.

[0080] In step S4', instead of increasing the flow rate of the process gas entering the sample space 9, the controller 15 closes the separation valve 123, thereby closing the outlet opening 131 of the turbomolecular pump 97. When the turbomolecular pump 97 is operating, the closure of the outlet opening 131 causes an increase in the gas pressure at the outlet opening 131. In this case, when steps S4' and S5' are performed, the controller 15 operates the leak valve 151, causing the pressure sensor 157 to record a constant gas pressure in the sample space 9. Therefore, the size of the orifice 65 of the inserted aperture 63 (which limits the gas flow rate from the sample space 9 into the second intermediate vacuum space 7) limits the rate at which the gas pressure at the outlet opening 131 of the turbomolecular pump 97 increases.

[0081] In step S5', the controller 15 records the operating current of the turbomolecular pump 97 using the current sensor 135. More specifically, the controller 15 records time-series data of the operating current supplied to the turbomolecular pump 97, such as, for example... Figure 9 As shown in the image.

[0082] In step S6', the controller 15 compares the time-series data of the operating current supplied to the turbomolecular pump 97 (captured in step S5') with predetermined calibration data, such as... Figure 9 As shown in (described later). In this case, the controller 15, for example, determines: to calculate the difference between the operating currents of the turbomolecular pump 97 at different times, so as to calculate the gradient of the operating current of the turbomolecular pump 97 over time. The controller 15 can then compare the calculated gradient of the recorded time-series data with the gradient of the calibration data of the corresponding aperture 63, and select, for example, aperture 63, for which the gradient in the calibration data has the smallest difference relative to the calculated gradient of the recorded time-series data of the operating current of the turbomolecular pump 97. Alternatively, the selection of aperture 63 can also be implemented as described in the method according to the first embodiment, such that the calibration data of the selected aperture 63 has a least-squares value relative to the recorded time-series data of the operating current of the turbomolecular pump 97.

[0083] It should also be noted that in the method according to the second embodiment, step S11 can be omitted, such as... Figure 6 As shown in the diagram. Since the gradual increase in gas pressure in sample space 9 does not exceed the limit pressure in sample space 9, protection valve 25 can also be opened without re-evacuating sample space 9 using turbomolecular pump 97, so that steps S13 to S17 can be performed. Furthermore, if the gas pressure in sample space 9 does not exceed the maximum permissible gas pressure without an inserted aperture, protection valve 25 can be opened during the aperture determination method. Since any aperture would limit the gas flow into the second intermediate vacuum space 7 compared to the case without an inserted aperture, it can be assumed that opening protection valve 25 poses no risk if the maximum permissible gas pressure without an inserted aperture is not exceeded.

[0084] Figure 7 The figure illustrates a flowchart of a method according to a third embodiment. The method according to the third embodiment includes steps S18 to S29.

[0085] First, such as Figure 3As shown, the user of the electron beam microscope 1 selects an aperture 63 from group 185 and inserts the selected aperture 63 into the aperture arrangement 57 in step S18. In steps S19 and S20, the controller 15 then begins evacuating the sample space 9 and the second intermediate vacuum space 7. In one case, where the turbomolecular pump 97 continues to operate when the aperture 63 is inserted, the separation valve 137 is closed (for this reason). The controller 15 begins to close the separation valve 123, open the static mode valve 119, and the separation valves 115 and 141, and operates the forepump 95. For example, if the pressure sensor 157 records a pressure corresponding to the forepump vacuum, the controller 15 closes the separation valve 115 and opens the separation valves 123 and 137. In another case, where the turbomolecular pump 97 does not operate when the aperture 63 is inserted, the controller 15 first begins to operate the forepump 95 with valves 119, 123, 137, and 141 open. The separation valve 115 can be closed or open. Afterwards, the controller 15 closes the separation valve 115 and operates the turbomolecular pump 97.

[0086] Then, controller 15 operates turbomolecular pump 97 to evacuate sample space 9 and second intermediate vacuum space 7 while separation valve 141 is open. If pressure sensor 157 records a predetermined low gas pressure, controller 15 closes separation valve 141. Controller 15 also opens protection valve 25 by operating actuator 33, wherein the protection valve remains open during the steps of the method according to the third embodiment.

[0087] If the sample 23 has not previously been mounted on the sample holder 73 (e.g., through the aforementioned door at the sample space 9), and if atmospheric pressure is present in the sample space 9, in step S21, the user unlocks the lock 79 and inserts the sample 23 into the sample space 9, and then the user mounts the sample on the sample holder 73. In step S22, in the software of the electron beam microscope 1, the user then inputs a desired target gas pressure for the sample space 9, which will be used to prevent the sample 23 from being charged. The set target gas pressure is then received by the controller 15. It should be noted that the possibilities for setting the target gas pressure in the software according to the third embodiment are not limited. In particular, the user can set any desired target gas pressure for the sample space 9.

[0088] In step S23, the controller 15 gradually increases the opening of the leakage valve 151 to gradually increase the flow rate of the process gas entering the sample space 9. As the controller 15 gradually increases the flow rate of the process gas entering the sample space 9, the controller 15 continues to proceed to steps S24 to S27.

[0089] In step S24, the controller 15 receives the gas pressure in the sample space 9 recorded by the pressure sensor 157 and compares the gas pressure with the target gas flow rate. If the target gas flow rate has been reached in the sample space 9, the controller 15 directly proceeds to step S27. If the gas pressure in the sample space 9 recorded by the pressure sensor 157 is less than the target gas pressure, the controller 15 proceeds to step S25.

[0090] In step S25, controller 15 receives the operating current of turbomolecular pump 97 recorded by current sensor 135. Then, controller 15 compares the recorded operating current of turbomolecular pump 97 with a predetermined threshold. If the recorded operating current of turbomolecular pump 97 is greater than the threshold, controller 15 proceeds to step S27. However, if the recorded operating current of turbomolecular pump 97 is less than the threshold, controller 15 returns to step S23 and further increases the flow rate of the process gas entering sample space 9 by further opening leak valve 151. For example, the operating current of turbomolecular pump 97 recorded at a predetermined low pressure in sample space 9 can be defined as a threshold such that once the operating current of turbomolecular pump 97 increases, the increase in the flow rate of the process gas entering sample space 9 stops. Since turbomolecular pump 97 must always be supplied with a minimum operating current during operation, the operating current of turbomolecular pump 97 initially remains constant within the low gas pressure range in sample space 9 and only increases from a specific gas pressure in sample space 9 (depending on the inserted aperture 63), for example from... Figure 8 This is clearly evident. Accordingly, the threshold in step S26 can be the constant operating current of the turbomolecular pump 97, such that when the operating current of the turbomolecular pump 97 increases, the increase in the flow rate of the process gas entering the sample space 9 is stopped, and the method continues to step S27.

[0091] In steps S27 to S29, the controller 15 captures a particle optical image. For this purpose, in step S27, the controller 15 sequentially supplies different potentials to the deflection arrangement 85 to scan the sample 23 with the electron beam 17. Furthermore, in step S28, for each incident point of the electron beam 17 on the sample 23, the detector 89 detects a signal, such as, for example, secondary electrons emitted by the sample 23 when the electron beam 17 is incident. By assigning the incident position on the sample 23 to the recorded signal, in step S29, the controller 15 generates and stores a particle optical image. It should be noted that the aperture 63 inserted into the electron beam microscope 1 is not determined, therefore the generated particle optical image is not stored along with this information.

[0092] Using the method described above according to the third embodiment, even without information about the aperture 63 inserted in the electron beam microscope 1, the flow rate of the process gas entering the sample space 9 is stopped before the gas pressure in the sample space 9 reaches a value that would exceed the limit pressure allowed by the inserted aperture 63. Accordingly, the above objective can be achieved because even if an excessively high target gas pressure is set in the software of the electron beam microscope 1, the user of the electron beam microscope 1 cannot cause the gas pressure in the sample space 9 to exceed the allowable limit pressure.

[0093] It should be noted that if step S26 determines that the operating current of the turbomolecular pump 97 exceeds a predetermined threshold, the instantaneous gas pressure in the sample space 9 can be recorded by the pressure sensor 157, and this recorded gas pressure can be defined as the limiting pressure in the software. Specifically, in this case, the slider displayed in the software can also be limited to the defined limiting pressure in a manner similar to that in the first and second embodiments. Furthermore, in the case of defining a new limiting pressure, the user can be notified, and it can be suggested to insert a different aperture that may be more suitable for the predefined target pressure.

[0094] Figure 8 The illustration shows a graph illustrating calibration data used in the method according to the first embodiment. Specifically, in Figure 5 The calibration data is used in step S6 as shown. Figure 8 In the graph, the X-axis represents the gas pressure in sample space 9, and the Y-axis represents the electrical power of turbomolecular pump 97. The X-axis and Y-axis are logarithmically proportional. Figure 8 The diagram illustrates the calibration data for apertures A, B, and C, and also shows the calibration data without aperture 63 inserted in aperture arrangement 57. Without aperture 63 inserted in aperture arrangement 57, the opening 61 of mounting member 59 limits the flow rate of gas from sample space 9 into second intermediate vacuum space 7.

[0095] exist Figure 8 It is evident that, with the aperture 63 inserted, the operating current or electrical power of the turbomolecular pump 97 has a constant range under the low gas pressure in the sample space 9. The larger this constant range, the smaller the aperture 65 of the aperture 63, because the flow rate of gas entering the second intermediate vacuum space 7 from the sample space 9 is lower. Accordingly, different apertures 63 cause different variations in the operating current or electrical power of the turbomolecular pump 97 with the gas pressure in the sample space 9, thereby allowing the identification of the inserted aperture 63 to be determined in the method according to the first embodiment.

[0096] For example, the data recorded in step S5 is similar to Figure 8The relationship between the changes in aperture B is shown. In this case, the controller 15 selects the identifier B of the inserted aperture body 63 in steps S6 and S7.

[0097] The table below shows the mapping between predetermined limit pressures and different aperture diaphragm 63 identifiers. For identifier B, the controller 15 then determines, for example, a limit pressure of 200 Pa according to the table shown below, and restricts the possibility for the user to set the target gas pressure to this value in the software of the electron beam microscope 1.

[0098]

[0099] Figure 9 The illustration shows a graph illustrating calibration data used in the method according to the second embodiment. Specifically, in Figure 6 The calibration data is used in step S6' shown. Figure 9 In the graph, the X-axis represents time, and the Y-axis represents the ratio of electrical power to the constant gas pressure set in sample space 9. Figure 9 The chart illustrates calibration data for apertures with circular holes 65, which have diameters of 350 µm, 1 mm, and 4.2 mm.

[0100] exist Figure 9 It is evident that for different inserted apertures 63, the operating current or electrical power of the turbomolecular pump 97 increases at different rates. Then, the gradient determined from the time-series data of the operating current or electrical power of the turbomolecular pump 97 can represent the identifier of the aperture 63. Figure 9 In the case shown, the designation is the diameter of the aperture 65 of the aperture body 63.

[0101] If, for example, the time-series data recorded in step S5' according to the second embodiment is similar to Figure 9 For the time-series data with an aperture diameter of 4.2 mm shown, in step S6', the controller can calculate the gradient of the recorded time-series data and determine that there is a small difference between the gradient of the recorded time-series data and the gradient of the calibration data with an aperture diameter of 4.2 mm. Therefore, in step S7 according to the second embodiment, the controller 15 selects 4.2 mm as the identifier for the inserted aperture 63. Then, based on the table shown above, the controller 15 can determine that the limiting pressure is approximately 600 Pa, and in the software of the electron beam microscope 1', the possibility of the user setting the target gas pressure to this limiting pressure can be restricted.

[0102] Using the methods according to the first, second, and third embodiments, it is impossible for the user to make the gas pressure in the sample space 9 exceed the limit pressure allowed by the inserted aperture 63. Therefore, the above-mentioned problem can be solved and the objective can be achieved.

Claims

1. A method for manipulating a particle beam system (1, 1'), wherein, This method includes a measurement method and an aperture determination method. The particle beam system (1, 1') includes: Particle beam source (11), which is used to generate particle beam (17). A sample holder (73) on which a sample (23) intended to be irradiated by the particle beam (17) can be arranged. The particle beam source (11) is arranged in the pumpable air source space (3); A ventable sample space (9) in which the sample holder (73) is arranged; A pumpable intermediate vacuum space (7) is separated from the source space (3) and connected to the source space via a first opening (21, 27), through which the particle beam (17) passes in the measurement method; and the pumpable intermediate vacuum space is separated from the sample space (9) and connected to the sample space via a second opening (61, 65), through which the particle beam (17) passes in the measurement method; and Multiple aperture bodies (63), each having an aperture (65), wherein the apertures (65) of different aperture bodies (63) have different cross-sectional areas and / or different lengths; The measurement method includes inserting any desired aperture (63) into these apertures (63) such that the aperture (65) of the aperture (63) provides the second opening; The method for determining the aperture includes: A turbomolecular pump (97) is used to evacuate the intermediate vacuum space (7); Repeatedly record the values ​​of the variables characterizing the operating current supplied to the turbomolecular pump (97); and The limiting pressure of the sample space (9) during the measurement method is determined based on multiple recorded values ​​of the variable characterizing the operating current supplied to the turbomolecular pump (97).

2. The method of claim 1, wherein, This measurement method also includes: The sample (23) is placed on the sample holder (73); The particle beam (17) was directed onto the sample (23); and The signal generated by the particle beam (17) at the sample (23) is detected.

3. The method according to claim 2, further comprising: The sample (23) was scanned with the particle beam (17) and the signal generated by the particle beam (17) was repeatedly detected; Generate particle optical images based on the detected signals; as well as Store the generated particle optical images.

4. The method according to any one of claims 1 to 3, wherein, The measurement method also includes evacuating the sample space (9).

5. The method according to claim 4, wherein, This measurement method also includes: Record the gas pressure in the sample space (9); The flow rate of gas entering the sample space (9) is increased based on the recorded gas pressure and the determined limit pressure.

6. The method according to claim 5, wherein This measurement method also includes: Once the ultimate pressure is reached, the increase is stopped and the gas flow rate is maintained.

7. The method according to any one of claims 1 to 6, wherein The method for determining the aperture includes: The sample space (9) was evacuated until a predetermined low pressure was reached; then Increase the flow rate of the gas entering the sample space (9); and During the process of increasing the flow rate, the values ​​of the gas pressure in the sample space (9) and the value of the variable characterizing the working current supplied to the turbomolecular pump (97) are repeatedly recorded; The process of determining the ultimate pressure is also based on multiple recorded values ​​of the gas pressure.

8. The method according to any one of claims 1 to 6, wherein The method for determining the aperture includes: The sample space (9) was evacuated until a predetermined low pressure was reached; then Close the outlet opening (131) of the turbomolecular pump (97). Gas is supplied into the sample space (9) to create a predetermined increased pressure within the sample space (9); and During the supply of the gas, the value of the variable characterizing the supply of the operating current to the turbomolecular pump (97) is repeatedly recorded; Determining the ultimate pressure also includes calculating at least one difference between these recorded values, and determining the ultimate pressure based on the calculated at least one difference.

9. The method according to claim 7 or 8, wherein After the predetermined low pressure is reached, the sample space (9) is no longer evacuated in the aperture determination method.

10. The method according to any one of claims 7 to 9, in, The predetermined low pressure is less than 10 -4 millibar.

11. The method according to any one of claims 1 to 10, wherein, Each aperture (63) has an identifier that can identify the corresponding aperture (63), and Determining the ultimate pressure includes determining the identifier of the inserted aperture (63) and determining the ultimate pressure based on the identified identifier of the inserted aperture (63).

12. The method of claim 11, wherein, The marking indicates the diameter and / or length of the aperture (65) of the aperture body (63).

13. The method according to claim 11 or 12 in conjunction with claim 3, further comprising: The determined identifier of the inserted aperture (63) is stored together with the particle optical image.

14. The method according to any one of claims 11 to 13 in conjunction with claim 7, Also included are calibration methods, wherein, The calibration method includes: Insert an aperture body (63) with the given identifier; The turbomolecular pump (97) was used to evacuate the sample space (9) until a predetermined low pressure was reached; then Increase the flow rate of the gas entering the sample space (9); During the increase of the flow rate, the values ​​of the gas pressure in the sample space (9) and the variable characterizing the supply of the operating current to the turbomolecular pump (97) were repeatedly recorded; and The recorded values ​​of the gas pressure in the sample space (9) and the recorded values ​​of the variable characterizing the operating current supplied to the turbomolecular pump (97) are stored together with the given identifier; The method for determining the aperture also includes: The recorded values ​​of the gas pressure in the sample space (9) and the recorded values ​​of the variable characterizing the operating current supplied to the turbomolecular pump (97) are compared with the stored values ​​in this aperture determination method; and The identification of the inserted aperture body (63) in the aperture determination method includes comparing the value recorded in the aperture determination method with the value stored in the calibration method, and selecting, according to a predetermined deviation standard, the identification of those values ​​that have the smallest deviation relative to the value recorded in the aperture determination method and storing them together.

15. The method according to any one of claims 11 to 13 in conjunction with claim 8, Also included are calibration methods, wherein, The calibration method includes: Insert an aperture body (63) with the given identifier; The turbomolecular pump (97) is used to evacuate the sample space (9) until the predetermined low pressure is reached; then Close the outlet opening (131) of the turbomolecular pump (97). Gas is supplied into the sample space (9) to create a predetermined increased pressure in the sample space (9); During the supply of the gas, the value of the variable characterizing the supply of the operating current to the turbomolecular pump (97) is repeatedly recorded; and The recorded value of the variable characterizing the supply of the operating current to the turbomolecular pump (97) is stored together with the given identifier; The method for determining the aperture also includes: The value of the variable representing the supply of the operating current to the turbomolecular pump (97), as recorded in the aperture determination method, is compared with the stored value; and The identification of the inserted aperture body (63) in the aperture determination method includes comparing the value recorded in the aperture determination method with the value stored in the calibration method, and selecting, according to a predetermined deviation standard, the identification of those values ​​that have the smallest deviation relative to the value recorded in the aperture determination method and storing them together.

16. The method according to claim 14 or 15, wherein, According to the predetermined deviation standard, the minimum deviation has a least squares value.

17. The method according to any one of claims 1 to 16, wherein, The aperture determination method is performed each time after the aperture body (63) is inserted and before the particle beam (17) is guided.

18. A method for manipulating a particle beam system (1, 1'), in, The particle beam system (1, 1') includes: Particle beam source (11), which is used to generate particle beam (17). A sample holder (73) on which a sample (23) intended to be irradiated by the particle beam (17) can be arranged. The particle beam source (11) is arranged in the pumpable air source space (3); A ventable sample space (9) in which the sample holder (73) is arranged; A pumpable intermediate vacuum space (7) is separated from the source space (3) and connected to the source space via a first opening (21, 27), through which the particle beam (17) passes in the measurement method; and the pumpable intermediate vacuum space is separated from the sample space (9) and connected to the sample space via a second opening (61, 65), through which the particle beam (17) passes in the measurement method; and Multiple aperture bodies (63), each having an aperture (65), wherein the apertures of different aperture bodies (63) have different cross-sectional areas and / or different lengths; The method includes: Insert any desired aperture (63) into these aperture bodies (63) such that the aperture (65) of the aperture body (63) provides the second opening; A turbomolecular pump (97) is used to evacuate the intermediate vacuum space (7); Receive the flow rate of the gas entering the sample space (9); The flow rate of the gas entering the sample space (9) is increased towards the received value of the flow rate of the gas entering the sample space (9); Repeatedly record the values ​​of the variables that characterize the operating current supplied to the turbomolecular pump (97); If the value of the variable characterizing the operating current supplied to the turbomolecular pump (97) reaches a predetermined limit, the process of increasing the flow rate of the gas entering the sample space (9) is terminated; and Issue a notification regarding the termination of the process of increasing the flow rate of the gas entering the sample space (9).

19. The method according to claim 18, wherein, The flow rate of the gas entering the sample space (9) is gradually increased in steps of predetermined steps towards the received value of the flow rate of the gas entering the sample space (9).

20. The method according to claim 18 or 19, further comprising: Before increasing the flow rate of the gas entering the sample space (9), the sample (23) is placed on the sample holder (73); When the flow rate of the gas entering the sample space (9) has reached the receiving value, the particle beam (17) is guided onto the sample (23); as well as The signal generated by the particle beam (17) at the sample (23) is detected.

21. The method of claim 20, further comprising defining the instantaneous flow rate of the gas entering the sample space (9) as the limit inflow rate when the process of increasing the flow rate of the gas entering the sample space (9) is terminated.

22. The method of claim 21, further comprising: Receive another value for the flow rate of the gas entering the sample space (9); as well as If another received value of the flow rate of the gas entering the sample space (9) exceeds the defined limit flow rate, a notification is issued.

23. The method according to any one of claims 18 to 22, It also includes evacuating the sample space (9) until a predetermined low pressure is reached before increasing the flow rate of the gas entering the sample space (9).

24. The method according to claim 23, in, The predetermined low pressure is less than 10 -4 millibar.

25. A particle beam system (1, 1'), comprising: Particle beam source (11), which is used to generate particle beam (17). A sample holder (73) on which a sample (23) intended to be irradiated by the particle beam (17) can be arranged. The particle beam source (11) is arranged in the pumpable air source space (3); A ventable sample space (9) in which the sample holder (73) is arranged; A pumpable intermediate vacuum space (7) is separated from the source space (3) and connected to the source space via a first opening (21, 27), through which the particle beam (17) passes in the measurement method; and the pumpable intermediate vacuum space is separated from the sample space (9) and connected to the sample space via a second opening (61, 65), through which the particle beam (17) passes in the measurement method. Multiple apertures (63), each having an aperture (65), wherein the apertures (65) of different apertures (63) have different cross-sectional areas and / or different lengths; and Controller (15, 167), configured to cause the particle beam system (1, 1') to perform an aperture determination method after inserting any desired aperture (63) into the aperture (63) such that the aperture (65) of the aperture (63) provides the second opening, the aperture determination method comprising: A turbomolecular pump (97) is used to evacuate the intermediate vacuum space (7); Repeatedly record the values ​​of the variables characterizing the operating current supplied to the turbomolecular pump (97); and The limiting pressure of the sample space (9) during the measurement method is determined based on multiple recorded values ​​of the variable characterizing the operating current supplied to the turbomolecular pump (97).

26. A particle beam system (1, 1'), comprising: Particle beam source (11), which is used to generate particle beam (17). A sample holder (73) on which a sample (23) intended to be irradiated by the particle beam (17) can be arranged. The particle beam source (11) is arranged in the pumpable air source space (3); A ventable sample space (9) in which the sample holder (73) is arranged; A pumpable intermediate vacuum space (7) is separated from the source space (3) and connected to the source space via a first opening (21, 27), through which the particle beam (17) passes in the measurement method; and the pumpable intermediate vacuum space is separated from the sample space (9) and connected to the sample space via a second opening (61, 65), through which the particle beam (17) passes in the measurement method. Multiple apertures (63), each having an aperture (65), wherein the apertures (65) of different apertures (63) have different cross-sectional areas and / or different lengths; and The controller (15, 167) is configured to cause the particle beam system (1, 1') to perform the following steps after any desired aperture (63) is inserted into the aperture (63) such that the aperture (65) of the aperture (63) provides the second opening: A turbomolecular pump (97) is used to evacuate the intermediate vacuum space (7); Receive the flow rate of the gas entering the sample space (9); The flow rate of the gas entering the sample space (9) is increased towards the received value of the flow rate of the gas entering the sample space (9); Repeatedly record the values ​​of the variables that characterize the operating current supplied to the turbomolecular pump (97); If the value of the variable characterizing the operating current supplied to the turbomolecular pump (97) reaches a predetermined limit, the process of increasing the flow rate of the gas entering the sample space (9) is terminated; and Issue a notification regarding the termination of the process of increasing the flow rate of the gas entering the sample space (9).

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