Method for operating a particle beam system and particle beam system

Abstract

A method for operating a particle beam system includes: evacuating a sample space in a first operating mode; evacuating a source space and an intermediate vacuum space by operating a first ion-getter pump and a second ion-getter pump using a shared high-voltage source; measuring the current supplied from the high-voltage source to the first ion-getter pump and the second ion-getter pump, and determining the pressure in the intermediate vacuum space based on the measured current. The method further includes: evacuating the sample space in a second operating mode; evacuating the source space by operating the first ion-getter pump using a high-voltage source without operating the second ion-getter pump using the high-voltage source; measuring the current supplied from the high-voltage source to the first ion-getter pump, and determining the pressure in the source space based on the measured current.

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 enable operation of the particle beam source and to prevent contamination, a vacuum system is provided that generates a high or ultra-high vacuum in the source space where the particle beam source is located. For this purpose, the vacuum system includes, for example, an ion extraction pump.

[0003] On the other hand, the gas pressure in the sample space where the sample is placed continuously increases, so the gas pressure maintained by the vacuum system in the sample space is much higher than the gas pressure in the source space. Due to the large pressure difference between the source space and the sample space, an intermediate vacuum space is set up. Another ion suction pump of the vacuum system generates a vacuum in this intermediate vacuum space, and the gas pressure of this vacuum is between the gas pressure of the vacuum in the source space and the gas pressure of the vacuum in the sample space.

[0004] The ion-getting pump operates via a high-voltage source and ionizes gas particles. These ionized particles are then electromagnetically attracted and held in place by electrodes within the pump. The operating current of the ion-getting pump is approximately proportional to the gas pressure within it. Therefore, in a particle beam system, the gas pressure in the source space is determined by the current supplied to the ion-getting pump in the source space, and the gas pressure in the intermediate vacuum space is determined by the current supplied to another ion-getting pump in the intermediate vacuum space.

[0005] Typically, the vacuum system of a particle beam system is a precision system that includes a large number of expensive components that require procurement, assembly, and maintenance. Summary of the Invention

[0006] Therefore, the object of this invention is to provide a particle beam system with a simplified vacuum system.

[0007] The particle beam system used in the method described below includes a particle beam source, a evacuable source space, an evacuable sample space, an evacuable intermediate vacuum space, a first ion-absorption pump for evacuating the source space, a second ion-absorption pump for evacuating the intermediate vacuum space, and a high-voltage source. In this configuration, the intermediate vacuum space is separated from the source space and connected to the source space via a first opening, and the intermediate vacuum space is separated from the sample space and connected to the sample space via a second opening. In the measurement method, a particle beam generated by the particle beam source and guided to a sample disposed in the sample space passes through both the first and second openings.

[0008] In this context, it should be noted that a pumpable space is a space in which gas is removed, thus reducing the gas pressure. Furthermore, in the following text, the terms "connection" and "phase connection" refer to a point through which gas can flow. 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 compared to the volume of one vacuum space can flow into another, 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. Signal lines and current lines are referred to herein as electrical connections.

[0009] The proposed method for solving the above problems includes a first operating mode and a second operating mode. The first operating mode includes: evacuating the sample space; operating a first ion-absorption pump and a second ion-absorption pump via a shared high-voltage source to evacuate the source space and the intermediate vacuum space, or keeping them evacuated such that the pressure in the source space is lower than the pressure in the intermediate vacuum space and the pressure in the intermediate vacuum space is lower than the pressure in the sample space; and measuring the current supplied from the high-voltage source to the first and second ion-absorption pumps and determining a value representing the pressure in the intermediate vacuum space based on the measured current. The second operating mode includes: evacuating the sample space; operating the first ion-absorption pump via a high-voltage source to evacuate the source space without operating the second ion-absorption pump via the high-voltage source; and measuring the current supplied from the high-voltage source to the first ion-absorption pump and determining a value representing the pressure in the source space based on the measured current.

[0010] Specifically, the above method allows for the joint operation of two ion-getting pumps using a single high-voltage source, while also potentially recording the gas pressures in the source space and the intermediate vacuum space. For example, the particle beam system can alternately switch between operating a single ion-getting pump and operating two ion-getting pumps. The vacuum generated in the source space has a much lower gas pressure than the vacuum in the intermediate vacuum space; therefore, the current supplied to the ion-getting pump in the intermediate vacuum space is much larger than the current supplied to the ion-getting pump in the source space. If the two ion-getting pumps are operated in conjunction with a high-voltage source, the current supplied to the ion-getting pump in the source space is correspondingly negligible, and thus the current provided by the high-voltage source is essentially defined by the vacuum in the intermediate vacuum space. During this operation, the gas pressure in the intermediate vacuum space can therefore be determined based on the current provided by the high-voltage source. If only the ion-getting pump in the source space is operated with a high-voltage source, the gas pressure in the source space can be determined based on the current provided by the high-voltage source.

[0011] Since the ion-getting pump in the intermediate vacuum space is shut down for this purpose, the measurement is preferably performed within a short period of time. Furthermore, the shutdown of the ion-getting pump in the intermediate vacuum space is affected by the hardware used; for example, the current supplied to the ion-getting pump in the intermediate vacuum space will not drop to zero instantaneously after shutdown. Accordingly, determining the gas pressure in the source space based on the current supplied by the high-voltage source can advantageously be performed after a transition period, after which the current is no longer actually supplied to the ion-getting pump in the intermediate vacuum space. Additionally, when the ion-getting pump in the intermediate vacuum space is shut down, the gas pressure in the source space will increase for a short period of time because gas flows from the intermediate vacuum space into the source space. If the current supplied to the ion-getting pump in the source space is recorded multiple times within the time period, an average value can be formed to prevent fluctuations in the recorded values.

[0012] This method allows the vacuum system to be operated by a single high-voltage source for two ion suction pumps, thereby eliminating a large number of components in the vacuum system and providing a simplified vacuum system.

[0013] It should be noted that the current measured in the second operating mode can also be used to subtract the current supplied to the ion-absorption pump in the first operating mode from the total current provided by the high-voltage source, or to eliminate the contribution of the ion-absorption pump in the source space.

[0014] According to some embodiments, the method further includes disconnecting the switch to disconnect the second ion pump from the high voltage source in a second operating mode, and closing the switch to connect the second ion pump to the high voltage source in a first operating mode. For example, the current supply to the ion pump is controlled by a high voltage controller including a high voltage source and a switch that enables the second ion pump to disconnect from the high voltage source. For example, the switch may be a transistor.

[0015] According to some embodiments, the particle beam system further includes a first valve disposed in a vacuum connection between the intermediate vacuum space and the pump evacuating the sample space. This first valve is closed in a first operating mode and can be opened in a second operating mode. For example, another valve can be disposed in the vacuum connection between the source space and the pump evacuating the sample space, and this other valve is closed in both operating modes. This valve is primarily used before the operation of the ion-absorption pump begins, for example by means of a turbomolecular pump, to generate a vacuum in the source space and the intermediate vacuum space, with the ion-absorption pump requiring this vacuum as a prerequisite. After the turbomolecular pump has evacuated the source space and the intermediate vacuum space, the ion-absorption pump operates in the first operating mode and both valves are closed. However, in the second operating mode, the first valve can be opened to mitigate the deterioration of the vacuum in the intermediate vacuum space, especially if the second operating mode is performed for a period of time, causing the gas pressure in the intermediate vacuum space to increase above the gas pressure required by the second ion-absorption pump.

[0016] According to some embodiments, the pressure value representing the intermediate vacuum space is determined based on a predetermined value representing the pressure in the intermediate vacuum space, and the pressure value representing the source space is determined based on a predetermined value representing the pressure in the source space. For example, a predetermined current can be stored together with a predetermined gas pressure, whereby the current measured in a first operating mode and / or a second operating mode can be assigned a gas pressure.

[0017] According to some embodiments, the method further includes placing a sample on a sample holder, and guiding a particle beam onto the sample and detecting a signal generated by the particle beam at the sample during a first operating mode and / or a second operating mode.

[0018] According to some embodiments, the method further includes shutting down the particle beam source and notifying the user of the particle beam system if the pressure in the source space exceeds a predetermined threshold. For example, if the high vacuum gas pressure in the source space increases, the cause may be a particle beam system malfunction, and the particle beam source can be shut down to avoid significant damage.

[0019] According to some embodiments, the measurement method involves the following operations of a particle beam system to capture particle optical images and / or process a sample with a particle beam. For example, for this purpose, a particle beam is generated by a particle beam source and directed onto the sample to induce desired physical effects for capturing particle optical images and / or for processing the sample.

[0020] According to some embodiments, the method includes recording a value representing the current flowing between the emitting material of the particle beam source and the accelerating electrode of the particle beam source, and determining the pressure in the source space based on that value. For example, if the gas pressure in the source space is high, many of the particles emitted by the emitting material of the particle beam source will interact with the gas located in the source space, thereby reducing the current flowing between the emitting material and the accelerating electrode at high gas pressure. Determining the pressure in the source space based on the value representing the current flowing between the emitting material of the particle beam source and the accelerating electrode of the particle beam source can advantageously be performed during a first operating mode, during which it would otherwise be impossible to determine the pressure in the source space. Therefore, for example, vacuum breaches and other defects can be reliably and rapidly detected even during the first operating mode.

[0021] According to a specific embodiment, the particle beam system includes a controller configured to cause the particle beam system to perform the methods described above.

[0022] According to a specific embodiment, the particle beam system includes no more than two ion uptake pumps. Multiple particle beam systems can form a larger overall system; in this case, for example, no more than two ion uptake pumps are provided for each of these particle beam systems. Attached Figure Description

[0023] The above embodiments will now be explained in more detail with reference to the accompanying drawings.

[0024] Figure 1 The illustration shows a first electron beam microscope suitable for performing the method of the present invention.

[0025] Figure 2 A second electron beam microscope suitable for performing the method of the present invention is illustrated.

[0026] Figure 3 The diagram shows... Figure 1 and Figure 2 The diagram shows a schematic structure of an ion aspiration pump.

[0027] Figure 4 The diagram shows... Figure 1 and Figure 2 The diagram shows a schematic structure of a high-voltage controller.

[0028] Figure 5 The illustration shows a flowchart illustrating a method according to one embodiment. Detailed Implementation

[0029] Figure 1The 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.

[0030] 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. Aperture 19 can, for example, serve as accelerating anode of electron beam source 11 and accelerate electrons emitted by electron beam source 11 along beam path 17. Since electron beam source 11 emits electrons at very different angles in some cases, not all emitted electrons will pass through opening 21 of aperture 19, but will be incident on aperture 19. If aperture 19 is also electrically connected to controller 15, for example for supplying anode potential by means of controller 15, electrons incident on aperture 19 flow to controller 15 via this electrical connection. Therefore, the controller 15 can also measure the current flowing to the controller 15 via the signal line 13, the electron beam source 11, and the aperture 19. This current depends on the gas pressure present in the source space 3, because electrons interact with the gas in the source space 3 on their way from the electron beam source 11 to the aperture 19. Additionally, increased gas pressure may increase contamination of the emitting material, resulting in fewer emitted electrons and fewer electrons incident on the aperture 19. Therefore, the controller 15 can also determine the gas pressure in the source space 3 by the current flowing between the electron beam source 11 and the aperture 19.

[0031] The protective valve 25 includes a sealing plate 31 and an actuator 33. The actuator 33 is electrically connected to the controller 15 via a signal line 35. If the actuator 33 is operated by the controller 15 via the signal line 35, the actuator moves the sealing plate 31 into or out of the beam path of the electron beam 17, thereby completely disconnecting or connecting the first intermediate vacuum space 5 and the second intermediate vacuum space 7, respectively. If the protective valve 25 is open and the electron beam 17 is directed onto the sample 23, the electron beam 17 passes through the protective valve 25.

[0032] 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.

[0033] 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.

[0034] 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 via a vacuum lock 69 using a guide mechanism 67 and inserts another aperture body into the mounting member 59 using the guide mechanism 67, allowing the user to replace the aperture body 63. It should be noted that... Figure 1 The guide mechanism 67 is illustrated, but in some embodiments, the guide mechanism is removed from the sample space 9 or pivoted laterally relative to the image field of the electron beam microscope 1 during the guidance of the electron beam 17 onto the sample 23.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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 through 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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. For instance, in such a FIB-SEM particle beam system, two ion suction pumps are provided for each type of generated particle beam.

[0054] Figure 3 The diagram shows... Figure 1 and Figure 2 The diagram illustrates the schematic structure of ion aspiration pumps 99 and 101. Each ion aspiration pump 99 and 101 includes two electrodes 185, one serving as an anode and the other as a cathode. Electrodes 185 are secured by mounting members 187. Figure 3 In the case shown, these mounting components include signal line 173 and signal line 175, respectively. For example, mounting component 187 may be made of a conductive material.

[0055] An electric field is generated between electrodes 185 by means of a potential supplied to them. Additionally, a magnetic field is generated perpendicular to the electric field, extending perpendicularly to the plane of the attached figure and... Figure 3 The symbol 191 indicates this. This magnetic field can be generated by a permanent magnet (not shown).

[0056] Electrons 189, with a velocity component parallel to the electric field generated by electrode 185, are deflected by a magnetic field onto a spiral path 193. Electrons 189 move along the spiral path 193 in a direction 191 toward the anode. The deflection of electrons 189 onto the spiral path 193 allows them to remain in the accumulation region between electrodes 185 for as long as possible. This increases the probability of electrons 189 interacting with gas particles 195 and causing positive or negative ionization of the gas particles 195. Positively ionized gas particles 195 are then accelerated in a direction 197 toward the cathode, incident on the cathode, and permanently or temporarily retained on the cathode by chemical or physical binding forces. In this case, positively ionized gas particles 195, due to their high pulse, can penetrate into the cathode material or be encapsulated by the atomized cathode material. Positively ionized gas particles 195 move substantially in a straight line to the cathode. Negatively ionized gas particles 195 are accelerated toward the anode in the opposite direction 197 and incident on the anode. The explanation given above, based on the example of gas particles 195 incident on the cathode, similarly applies to gas particles 195 incident on the anode. Therefore, ion-getter pumps 99 and 101 can further reduce the gas pressure in the source space 3 and the first intermediate vacuum space 5 by means of ionizing and retaining the gas particles. Specifically, during operation of ion-getter pumps 99 and 101, valves 161 and 163 can be permanently closed so that the pressure can be further reduced compared to the pressure present in the turbopump line 109.

[0057] Figure 4 The diagram shows... Figure 1 and Figure 2 The schematic structure of controller 167 shown is illustrated. Controller 167 includes a high-voltage source 199 electrically connected to ion pump 99 via signal line 173 and to ion pump 101 via signal line 175. The high-voltage source 199 generates a high voltage between signal line 173 and ground terminal 203 and also between signal line 175 and ground terminal 203. Ion pumps 99 and 101 are also, in their respective cases, connected to ground terminal 203 via ground line 201.

[0058] The controller 167 further includes a switch 205 that disconnects the electrical connection between the ion pump 101 and the high-voltage source 199 via signal line 175. Additionally, the controller 167 includes a current sensor 207 that records the current supplied from the high-voltage source 199 to the ion pumps 99 and 101. When switch 205 is closed, the current sensor 207 records the total current supplied to the first ion pump 99 and the second ion pump 101. When switch 205 is open, the current sensor 207 records the current supplied to the first ion pump 99.

[0059] The proposed method according to one embodiment is described in detail below. Figure 5 The illustration shows a flowchart illustrating a method according to one embodiment. Figure 5 The flowchart illustrates steps S1 to S12, wherein steps S1 to S5 form a first operating mode, and steps S6 to S12 form a second operating mode.

[0060] In the first operating mode, controller 15 begins evacuating sample space 9. Before at least a foreground vacuum is reached in sample space 9, first intermediate vacuum space 5, second intermediate vacuum space 7, and source space, controller 15 begins closing separation valves 123 and 137, opening static mode valve 119, and separation valves 115 and 141, and operates foreground pump 95. Alternatively, controller 15 may also keep separation valves 123 and 137 open to generate a foreground vacuum via turbomolecular pump 97. This is advantageous, for example, if transition line 105 is not provided. Additionally, controller 15 opens separation valves 161 and 163 via controller 167, causing source space 3 and the first intermediate vacuum space to also be evacuated by foreground pump 95. For example, if pressure sensor 157 records a pressure corresponding to the foreground vacuum, controller 15 closes separation valve 115 and opens separation valves 123 and 137.

[0061] Then, controller 15 operates turbomolecular pump 97 to evacuate sample space 9, first intermediate vacuum space 5, second intermediate vacuum space 7, and source space 3 with separation valves 141, 161, and 163 open. If pressure sensor 157 records a predetermined low gas pressure, controller 15 closes separation valves 161 and 163. Closure of separation valves 161 and 163 can also be performed later. For example, ion extraction pumps 99 and 101 can be put into operation first, followed by closing separation valves 161 and 163.

[0062] In step S2, the controller 167 operates the first ion-absorption pump 99 and the second ion-absorption pump 101 by generating a high voltage using a high voltage source 199 when the switch 205 is closed, and supplying the high voltage to the ion-absorption pumps 99 and 101. Specifically, the ion-absorption pumps 99 and 101, the turbomolecular pump 97, and the forepump 95 are operated such that the gas pressure in the source space 3 is lower than the gas pressure in the first intermediate vacuum space 5, the gas pressure in the first intermediate vacuum space 5 is lower than the gas pressure in the second intermediate vacuum space 7, and the gas pressure in the second intermediate vacuum space 7 is lower than the gas pressure in the sample space 9.

[0063] When the first ion pump 99 and the second ion pump 101 are operated, in step S3, the controller 167 records the total current provided by the high voltage source 199, or more precisely, the current supplied to the first ion pump 99 and the second ion pump 101.

[0064] Because the gas pressure in the first intermediate vacuum space 5 is much greater than the gas pressure in the source space 3, the current of the second ion suction pump 101 is much greater than the current of the first ion suction pump 99. According to a specific embodiment, the current of the ion suction pump 101 can be 10 times, particularly 25 times, particularly 100 times, or particularly 1000 times greater than the current of the ion suction pump 99. Correspondingly, for example, ignoring the current of the first ion suction pump 99, in step S4, the gas pressure in the first intermediate vacuum space 5 can be determined with sufficient accuracy based on the recorded current.

[0065] As described above, in step S3, the controller can also record the current flowing between the emitting material of the electron beam source 11 and the aperture 19. In step S4, the controller 15 can then determine the gas pressure in the source space 3 based on the current flowing between the emitting material of the electron beam source 11 and the aperture 19. This determination prevents defects that may occur during the first operating mode that are not taken into account, in which the gas pressure in the source space 3 cannot be determined by the gas pressure of the first ion suction pump 99.

[0066] The second operating mode begins from the first operating mode. For this purpose, a decision is made in step S5 regarding whether to switch from the first operating mode to the second operating mode. For example, a decision to switch to the second operating mode can be made every 1 minute, specifically every 10 minutes, specifically every 60 minutes, specifically every 3 hours, specifically every 12 hours, specifically every 24 hours, specifically every 3 days, in which case the method proceeds to step S6. If it is determined that switching to the second operating mode should not be performed, both ion aspiration pumps will continue to operate as described in step S2.

[0067] The second operating mode begins at step S6. In step S6, the controller 167 disconnects the power switch 205 to disconnect the second ion aspiration pump 101 from the high voltage source 199.

[0068] Controller 15 can operate turbomolecular pump 97 throughout the method. It should be noted that turbomolecular pump 97 can be operated with valves 141 and 25 open or closed. Switching to the second operating mode can occur at any time when valve 25 is closed, even if the sample space 9 is no longer being evacuated.

[0069] In step S7, controller 167 operates only the first ion pump 99 and not the second ion pump 101. For this purpose, switch 205 is turned off, thereby preventing the supply of high voltage or current to the second ion pump 101.

[0070] In step S8, the controller 167 then records the current supplied to the first ion aspiration pump 99 via the current sensor 207. Since the current provided by the high-voltage source 199 is only the current supplied to the first ion aspiration pump 101, the gas pressure in the source space can be determined in step S9 based on the recorded current. For example, in steps S4 and S9, the gas pressure can be determined by pre-storing various gas pressures and corresponding currents, and selecting the gas pressure corresponding to the measured current from the stored data in steps S4 and S9. Alternatively or additionally, for example, a predetermined functional relationship between current and gas pressure can also be stored, based on which the gas pressures of the first intermediate vacuum space 5 and the source space 3 are determined in steps S4 and S9.

[0071] In step S10, the controller 15 compares the gas pressure in the source space 3 with a predetermined threshold. If the gas pressure in the source space 3 is greater than the predetermined threshold, the controller 15 proceeds to step S11. If the gas pressure in the source space 3 is not greater than the predetermined threshold, the method proceeds to step S12.

[0072] In step S11, the controller 15 shuts off the electron beam source 11. In this case, a malfunction of the electron beam microscope 1 may exist, so shutting off the particle beam source 11 prevents further damage. Additionally, the controller 15 can open valves 161 and 163 via signal lines 165 and 171, thus evacuating the source space 3 and the first intermediate vacuum space 5 by means of the turbomolecular pump 97.

[0073] In step S12, controller 167 closes electrical switch 205, causing the second ion pump 101 to be electrically connected to the high voltage source 199 again, thereby switching controller 167 back to the first operating mode. Specifically, when electrical switch 205 is closed, the transition to step S2 occurs because high voltage is then supplied to both ion pumps 99 and 101.

[0074] Steps S6 to S12 are preferably executed quickly enough to minimize the deterioration of the vacuum present in the first intermediate vacuum space 5 due to the shutdown of the second ion suction pump 101. According to a specific embodiment, steps S7 to S12 are executed within 0.1 seconds, particularly 1 second, particularly 10 seconds. Steps S6 to S12 can be executed independently of the operation of other components of the electron beam microscope 1, provided that the protective valve 25 is closed or the pressure in the source space 3 and the first intermediate vacuum space 5 is sufficiently low. For example, switching between the first and second operating modes can be performed every 1 minute, particularly every 10 minutes, particularly every 60 minutes, particularly every 3 hours, particularly every 12 hours, particularly every 24 hours, particularly every 3 days.

[0075] It should be noted that the second operating mode can also be performed for a longer period than described above. For example, the second operating mode can be used to monitor changes in gas pressure in source space 3. For this purpose, steps S6 to S12 are performed over time periods of, for example, 1 minute, 10 minutes, 60 minutes, 3 hours, 12 hours, 24 hours, or 3 days. Advantageously, in this case, while performing steps S6 to S12, the first intermediate vacuum space 5, the second intermediate vacuum space 7, and the sample space 9 are evacuated by the turbomolecular pump 97. In particular, for this purpose, the controller 15 opens valve 163 before or after disconnecting switch 205 in step S6.

[0076] The method described above for operating electron beam microscopes 1 and 1' allows both ion suction pumps 99 and 101 to be operated using a shared high-voltage source 199. Furthermore, the gas pressure in the source space 3 and the gas pressure in the first intermediate vacuum space 5 can be determined by the current supplied to the ion suction pumps 99 and 101. Therefore, many components of the vacuum system can be eliminated, and a simplified vacuum system can be provided.

Claims

1. A method for manipulating a particle beam system (1, 1'), in, The particle beam system (1, 1') includes: Particle beam source (11); Vacuumable air source space (3); Vacuumable sample space (9); A pumpable intermediate vacuum space (5) is separated from the source space (3) and connected to the source space via a first opening (21), and the pumpable intermediate vacuum space is separated from the sample space (9) and connected to the sample space via a second opening (27, 61, 65), wherein, in the measurement method, a particle beam (11) generated by the particle beam source (11) and guided to the sample (23) arranged in the sample space (9) passes through the first opening and the second opening (21, 27, 61, 65). A first ion suction pump (99) is used to pump air from the source space (3); A second ion suction pump (101) is used to evacuate the intermediate vacuum space (5); and High voltage source (199); The method has a first operating mode, which includes: The sample space (9) was evacuated; The first ion aspiration pump (99) and the second ion aspiration pump (101) are operated by the high voltage source (199) to evacuate the source space (3) and the intermediate vacuum space (5), such that the pressure in the source space (3) is lower than the pressure in the intermediate vacuum space (5) and the pressure in the intermediate vacuum space (5) is lower than the pressure in the sample space (9); and The current supplied from the high-voltage source (199) to the first ion-absorption pump and the second ion-absorption pump (99, 101) is measured, and a value representing the pressure in the intermediate vacuum space (5) is determined based on the measured current; and The method has a second operating mode, which includes: The sample space (9) was evacuated; Without operating the second ion aspiration pump (101) via the high voltage source (199), the first ion aspiration pump (99) is operated via the high voltage source (199) to evacuate the source space (3); and The current supplied from the high voltage source (199) to the first ion aspiration pump (99) is measured and a value representing the pressure in the source space (3) is determined based on the measured current.

2. The method according to claim 1, further comprising: Disconnect switch (205) to disconnect the second ion aspiration pump (101) from the high voltage source (199) in the second operating mode; as well as Close the switch (205) so that the second ion aspiration pump (101) is connected to the high voltage source (199) in the first operating mode.

3. The method according to claim 1 or 2, in, The particle beam system (1, 1') also includes: The first valve (163) is disposed in the vacuum connection (113) between the intermediate vacuum space (5) and the pump (97) that evacuates the sample space (9); In this first operating mode, the first valve (163) is closed; and The first valve (163) is opened in the second operating mode.

4. The method according to any one of claims 1 to 3, in, The value representing the pressure in the intermediate vacuum space (5) is determined based on a predetermined value representing the pressure in the intermediate vacuum space (5); and The value representing the pressure in the source space (3) is determined based on a predetermined value representing the pressure in the source space (3).

5. The method according to any one of claims 1 to 4, further comprising: Arrange the sample (23) in the sample space (9); as well as During the first operating mode and / or during the second operating mode, the particle beam (17) is directed onto the sample (23) and the signal generated by the particle beam (17) at the sample (23) is detected.

6. The method according to any one of claims 1 to 5, It also includes shutting down the particle beam source (11) and notifying the user of the particle beam system (1, 1') if the pressure in the source space (3) exceeds a predetermined threshold.

7. The method according to any one of claims 1 to 6, in, The measurement method is performed by the following operation of the particle beam system (1, 1'): capturing particle optical images and / or processing the sample (23) with the particle beam (17).

8. A particle beam system (1, 1'), comprising: Particle beam source (11); Vacuumable air source space (3); Vacuumable sample space (9); A pumpable intermediate vacuum space (5) is separated from the source space (3) and connected to the source space via a first opening (21), and the pumpable intermediate vacuum space is separated from the sample space (9) and connected to the sample space via a second opening (27, 61, 65), wherein, in the measurement method, a particle beam (17) generated by the particle source (11) and guided to the sample (23) arranged in the sample space (9) passes through the first opening and the second opening (21, 27, 61, 65). A first ion suction pump (99) is used to pump air from the source space (3); A second ion pump (101) is used to pump air from the intermediate vacuum space (5). High voltage source (199); and A controller (15, 167) is configured to cause the particle beam system (1, 1') to perform the method according to any one of claims 1 to 7.

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