Charged particle beam device

Abstract

To provide a current measurement device which can determine a proper replacement timing of an ion pump.SOLUTION: A charged particle beam device includes: a charged particle generation part which generates charged particles; a chamber which houses the charged particle generation part; a decompression device which makes a gas in the chamber into ions to decompress the inside of the chamber; a connection pipe which connects the chamber with the decompression device; a shield member which is provided at the connection pipe and in an electrically floating state and shields the ions flowing from the decompression device to the chamber; and a measuring device which is electrically connected to the shield member and measures electric change of the shield member.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present embodiment relates to a charged particle beam device. [Background technology]

[0002] Charged particle beam devices such as mask drawing devices include an electron gun chamber that houses an electron gun that emits charged particles, and an ion pump that reduces the pressure inside the electron gun chamber. The ion pump reduces the pressure inside the electron gun chamber by ionizing and capturing the gas inside the electron gun chamber. If ions from the ion pump enter the electron gun chamber, they may induce unexpected discharges inside the electron gun chamber. In order to suppress such discharges, a shield that blocks ions generated by the ion pump is provided between the ion pump and the electron gun chamber. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2001-52643 A [Patent Document 2] JP 2000-223055 A [Patent Document 3] Japanese Patent Application Publication No. 60-039751 [Patent Document 4] Patent Publication No. 2021-099938 [Patent Document 5] Japanese Patent Application Publication No. 8-165570 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the shield must also be breathable to reduce pressure, so it cannot completely prevent ion backflow. As the ion pump continues to be used, the probability of discharge in the electron gun chamber increases as more ions flow back from the ion pump to the electron gun chamber. In this case, the ion pump needs to be replaced, but it was not possible to accurately determine the appropriate time to replace the ion pump.

[0005] Therefore, a charged particle beam device capable of determining the appropriate time to replace an ion pump is provided. [Means for solving the problem]

[0006] The charged particle beam device according to this embodiment includes a charged particle generator that generates charged particles, a chamber that houses the charged particle generator, a pressure reduction device that ionizes gas in the chamber to reduce the pressure inside the chamber, a connecting pipe that connects the chamber and the pressure reduction device, a shielding member that is provided on the connecting pipe, is in an electrically floating state, and blocks ions flowing from the pressure reduction device to the chamber, and a measuring instrument that is electrically connected to the shielding member and measures electrical changes in the shielding member.

[0007] The charged particle beam device may further include a feedthrough terminal arranged to penetrate a wall of either the chamber, the pressure reducing device or the connecting tube, and wiring electrically connected between the shielding member and the measuring device through the feedthrough terminal.

[0008] The measuring device may be provided outside the chamber and electrically connected to the shielding member via a feedthrough terminal.

[0009] The measuring device may apply a voltage to the shielding member.

[0010] The wiring may be covered with an insulating material outside the chamber, the pressure reducing device or the connecting pipe, but may not be covered with an insulating material inside the chamber, the pressure reducing device or the connecting pipe.

[0011] The shielding member may include a plurality of conductive members made of a conductive material, a frame material made of a conductive material and electrically connected to the plurality of conductive members and wiring, and fixing the position of the plurality of conductive members relative to the connecting tube, and an insulating section made of an insulating material and provided between the connecting tube and the frame material.

[0012] The frame may electrically connect the plurality of conductive members to the wiring, and the insulating portion may electrically isolate the frame and the plurality of conductive members from the chamber, the pressure reducing device, and the connecting pipe.

[0013] The measuring device may measure the amount of ions that reach the shielding member by measuring the current flowing through the shielding member.

[0014] The insulating member may be made of ceramic or ceramic containing metal. [Brief description of the drawings]

[0015] [Figure 1] 1 is a diagram showing the configuration of a charged particle beam device according to a first embodiment. [Diagram 2] FIG. 4 is a cross-sectional view showing a more detailed configuration of an electron gun chamber and an ion pump. [Diagram 3] FIG. 4 is a plan view showing an example configuration of a shield, a feed-through terminal, an ammeter, and wiring. [Figure 4] FIG. 4 is a cross-sectional view showing an example of the configuration of a shield. [Diagram 5] FIG. 4 is a cross-sectional view showing a configuration example of a shield according to a first modified example. [Figure 6] FIG. 11 is a cross-sectional view showing a configuration example of a shield according to a second modified example. [Figure 7] FIG. 11 is a cross-sectional view showing a configuration example of a shield according to Modification 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The present invention is not limited to the embodiment. The drawings are schematic or conceptual. In the specification and the drawings, the same elements are given the same reference numerals.

[0017] (First embodiment) 1 is a diagram showing the configuration of a charged particle beam apparatus according to a first embodiment. A charged particle beam apparatus 100 (hereinafter, apparatus 100) is, for example, an electron beam drawing apparatus equipped with an electron gun that emits an electron beam. However, the charged particle beam is not limited to an electron beam, and may be a beam using other charged particles such as an ion beam. Furthermore, this embodiment may be applied not only to drawing apparatuses, but also to apparatuses having a vacuum chamber such as inspection apparatuses.

[0018] The apparatus 100 is an example of a variable shaping type electron beam drawing apparatus, and includes a drawing unit 150 and a control and calculation unit 160.

[0019] The imaging unit 150 includes an electron lens barrel 102 and an imaging chamber 103 .

[0020] The electron barrel 102 can maintain a substantially vacuum atmosphere inside. The electron barrel 102 includes an electron gun 201, an illumination lens 202, a blanking deflector 212, a blanking aperture 214, shaping apertures 203 and 206, a projection lens 204, a shaping deflector 205, an objective lens 207, deflectors 208 and 209, and an electron gun chamber (turret) 217.

[0021] An electron gun 201 as a charged particle generator is housed in an electron gun chamber 217 as a chamber, and generates an electron beam as charged particles. The electron gun chamber 217 is connected to an ion pump 117 and is depressurized by the ion pump 117.

[0022] The illumination lens 202, the projection lens 204, and the objective lens 207 are all electromagnetic lenses that change excitation to converge the electron beam and adjust the imaging position (irradiation position). As shown in Fig. 1, these are arranged in the axial direction of the electron beam 200 from one end on the upstream side where the electron gun 201 is located to the downstream side where the stage 105 described later is located.

[0023] An illumination lens 202 illuminates an electron beam 200 emitted from an electron gun 201 onto a shaping aperture 203. The electron beam 200 shaped by the shaping aperture 203 is further projected by a projection lens 204 onto a shaping aperture 206. The position of the shaping aperture image on the shaping aperture 206 is controlled by a shaping deflector 205. This changes the shape and dimensions of the electron beam. The electron beam 200 transmitted through the shaping aperture 206 is aligned at the irradiation position by an objective lens 207, and then deflected by deflectors 208 and 209. The electron beam 200 has its irradiation position corrected by the deflector 208, and is then irradiated onto a mask 216 placed in the writing chamber 103.

[0024] A stage 105 is disposed inside the writing chamber 103. The stage 105 is driven in the X, Y, and Z directions by the control unit 110. A mask 216 to be processed is placed on the stage 105. The mask 216 may be, for example, a mask substrate such as quartz on which a light-shielding film such as a chromium (Cr) film or a molybdenum silicon (MoSi) film is formed, and a resist film is further formed thereon. A predetermined pattern is written on this resist film by the electron beam 200. The mask 216 may be, for example, a mask blank on which no pattern has yet been formed.

[0025] The control and calculation unit 160 includes a control unit 110 and an ion pump 117 .

[0026] The control unit 110 includes a drawing data storage unit 110a that stores drawing data, a shot data generation unit 110b that processes the drawing data to generate shot data, and a drawing control unit 110c that controls the electron lens barrel 102. The drawing data storage unit 110a is a storage unit that stores drawing data for drawing a pattern on the mask 216. The shot data generation unit 110b divides a drawing pattern defined by the drawing data and generates shot data. The drawing control unit 110c performs control to draw the above-mentioned drawing pattern at a predetermined position based on the shot data generated while moving the stage 105 in the longitudinal direction of the stripe region.

[0027] An ion pump 117 as a pressure reducing device is connected to the electron gun chamber 217 and draws a vacuum to reduce the pressure inside the electron gun chamber 217. The ion pump 117 reduces the pressure by ionizing the gas inside the electron gun chamber 217 and absorbing the ions. The electron gun chamber 217 is reduced to a high degree of vacuum by the ion pump 117. Although not shown, other regions of the electron tube 102 other than the electron gun chamber 217 are also reduced in pressure by other vacuum pumps.

[0028] 2 is a cross-sectional view showing a more detailed configuration of the electron gun chamber 217 and the ion pump 117. An electron gun 201 is provided in the electron gun chamber 217. The electron gun 201 has a cathode electrode, and a negative voltage of, for example, −50 kV is applied to it.

[0029] The ion pump 117 includes a pair of magnets 301 and 302 , a pair of cathode electrodes 303 and 304 , an anode electrode 305 , an anode voltage application band 310 , and a plug 320 .

[0030] The magnets 301 and 302 are permanent magnets with south and north poles, respectively, and provide a magnetic field between them. The cathode electrodes 303 and 304 are disposed inside between the magnets 301 and 302, and are grounded. The anode electrode 305 is disposed inside between the cathode electrodes 303 and 304, and a positive voltage is applied to it via an anode voltage application band 310. This generates an electric field between the anode electrode 305 and the cathode electrodes 303 and 304, and provides an electric field to the gas between them. The magnetic field by the magnets 301 and 302 and the electric field between the anode electrode 305 and the cathode electrodes 303 and 304 are applied in the same direction.

[0031] Anode voltage application band 310, which serves as a voltage application member, connects between anode electrode 305 and plug 320. A positive voltage of, for example, +7 kV is applied to plug 320, and anode voltage application band 310 applies the voltage from plug 320 to anode electrode 305. Anode voltage application band 310 is made of a conductive material, for example, SUS or the like.

[0032] A connecting pipe 400 is provided between the ion pump 117 and the electron gun chamber 217. The connecting pipe 400 maintains the space between the ion pump 117 and the electron gun chamber 217 airtight, and serves as a path through which gas from the inside of the electron gun chamber 217 passes to the ion pump 117. The connecting pipe 400 is made of a conductive material such as SUS. A shield 500 is provided midway along the connecting pipe 400.

[0033] The shield 500 as a shielding member is provided in the connecting tube 400 of the path connecting the electron gun chamber 217 and the ion pump 117, and blocks ions flowing back from the ion pump 117 to the electron gun chamber 217. The shield 500 is electrically isolated from the electron gun chamber 217, the connecting tube 400, and the ion pump 117, and is in an electrically floating state. The shield 500 has an outer shape that follows the inner wall of the connecting tube 400, and its outer diameter is approximately equal to or slightly smaller than the inner diameter of the connecting tube 400. The shield 500 is provided to ensure the conductance of gas from inside the electron gun chamber 217 to the ion pump 117, while suppressing ions generated by the ion pump 117 from entering the electron gun chamber 217. A more detailed configuration of the shield 500 will be described later with reference to FIGS. 3 to 7.

[0034] An insulating sleeve 503 is provided as an insulating member in the gap between the shield 500 and the connection pipe 400. The insulating sleeve 503 is made of an insulating material such as ceramic. The insulating sleeve 503 may be made of a high resistance material, for example, ceramic with a small amount of metal such as titanium. In this case, the insulating sleeve 503 is made of a high resistance material with a volume resistivity of, for example, about 10 to the power of 10 Ω·cm. This makes it possible to suppress charging of the insulating sleeve 503. By providing the insulating sleeve 503 between the shield 500 and the connection pipe 400, the shield 500 fits into the inner wall of the connection pipe 400 with almost no gap.

[0035] The feedthrough terminal 550 is provided to penetrate the wall of the electron gun chamber 217 while maintaining the reduced pressure state of the electron gun chamber 217. The feedthrough terminal 550 passes a wiring 570 through the wall between the inside and outside of the electron gun chamber 217 while being electrically isolated from the electron gun chamber 217. The feedthrough terminal 550 is electrically connected to the shield 500 and the ammeter 560 through the wiring 570. As a result, the ammeter 560 outside the electron gun chamber 217 is electrically connected to the shield 500 inside the connection tube 400 while maintaining the reduced pressure state of the electron gun chamber 217 and maintaining electrical isolation from the electron gun chamber 217. The feedthrough terminal 550 may be provided to penetrate the wall of the connection tube 400 or the ion pump 117. Even in this case, the feedthrough terminal 550 can electrically connect the shield 500 and the ammeter 560 through the wiring 570 while maintaining the reduced pressure state of the electron gun chamber 217.

[0036] The wiring 570 is electrically connected between the shield 500 and the ammeter 560 through the feed-through terminal 550. The wiring 570 is made of a low-resistance metal material such as copper or tungsten. The wiring 570 is covered with an insulating material (e.g., resin, enamel, etc.) outside the electron gun chamber 217, the ion pump 117, or the connecting tube 400. This can prevent the wiring 570 from coming into contact with other members, operators, etc., outside the electron gun chamber 217, the ion pump 117, or the connecting tube 400 and causing a short circuit. On the other hand, the wiring 570 is not covered with an insulating material inside the electron gun chamber 217, the ion pump 117, or the connecting tube 400, and is exposed. This can prevent the insulating material inside the electron gun chamber 217, the ion pump 117, or the connecting tube 400 from being charged, and can prevent the insulating material from causing gas generation in a reduced pressure atmosphere.

[0037] The ammeter 560 as a measuring device is provided outside the electron gun chamber 217 and is electrically connected to the shield 500 via a wiring 570 and a feed-through terminal 550. The ammeter 560 measures the current flowing through the shield 500. For example, when ions generated by the ion pump 117 reach the shield 500, an ion current caused by the ions flows through the shield 500. The ammeter 560 can calculate the number of ions generated and the frequency of generation by measuring the ion current. Note that, instead of the ammeter 560, any measuring device capable of measuring an electrical change in the shield 500 may be provided. For example, instead of the ammeter, a voltmeter that measures a voltage based on the current flowing through the shield 500 may be provided.

[0038] The ion pump 117 can maintain discharge in a reduced pressure environment by adding a magnetic field from the magnets 301, 302 to the electric field between the cathode electrodes 303, 304 and the anode electrode 305. As a result, electrons are generated between the anode electrode 305 and the cathode electrodes 303, 304, and gas colliding with the electrons is ionized and becomes positive ions. The positive ions collide with the cathode electrodes 303, 304 and sputter the cathode electrode material (e.g., titanium) from the cathode electrodes 303, 304. The sputtered cathode electrode material adsorbs the gas and attaches to the anode electrode 305 and the like. As a result, the ion pump 117 can remove the gas from the electron gun chamber 217 and reduce the pressure inside the electron gun chamber 217.

[0039] Most of the positive ions P generated by the ion pump 117 collide with the cathode electrodes 303 and 304. However, some of the positive ions P may attempt to move to the electron gun chamber 217 due to the cathode voltage (e.g., −50 kV) of the electron gun chamber 217. In this case, it is desirable for the shield 500 to capture the positive ions P while maintaining the conductance of the gas from the electron gun chamber 217.

[0040] Fig. 3 is a plan view showing an example of the configuration of the shield 500, the feed-through terminal 550, the ammeter 560, and the wiring 570. Fig. 4 is a cross-sectional view showing an example of the configuration of the shield 500.

[0041] All or part of the shield 500, the feedthrough terminal 550, and the ammeter 560 may be integrally configured, or the shield 500, the feedthrough terminal 550, and the ammeter 560 may be separable from one another and configured in combination.

[0042] The shield 500 includes a plurality of plate members 501 , a conductive frame 502 , and an insulating sleeve 503 .

[0043] The plurality of plate members 501 are arranged in the conductive frame 502 so that there are almost no gaps between them when the inside of the connection tube 400 is viewed from a first direction (the direction of the paper surface in FIG. 3) D1 from the ion pump 117 to the electron gun chamber 217. For example, as shown in FIG. 4, the plate members 501 have a chevron shape, and are arranged so that an upper end E1 of a certain plate member overlaps a lower end E2 of a plate member adjacent to this plate member when the connection tube 400 is viewed from the first direction D1. In this way, by arranging the adjacent plate members 501 so that they partially overlap, the shield 500 is configured so that the other side of the shield 500 cannot be seen when viewed from the first direction D1. Thereby, even if the positive ions P travel straight from the ion pump 117 to the electron gun chamber 217, the positive ions P collide with the plate members 501 and are blocked. As a result, the shield 500 can block the positive ions P. The plurality of plate members 501 are made of a material having electrical conductivity and corrosion resistance, such as SUS.

[0044] On the other hand, the multiple plate members 501 are spaced apart from one another and are not in direct contact with one another. Therefore, the multiple plate members 501 do not seal the inside of the conductive frame 502, allowing ventilation. In other words, the multiple plate members 501 do not impede the exhaust of the electron gun chamber 217. In this way, the shield 500 ensures ventilation from the electron gun chamber 217 to the ion pump 117, and can suppress the backflow of ions while maintaining good gas conductance.

[0045] More specifically, as shown in Fig. 4, the multiple plate members 501 each have a substantially V-shape in a cross section perpendicular to the extension direction of the plate members 501. That is, the multiple plate members 501 each have a so-called chevron shape. The plate members 501 each have substantially the same shape and size. Furthermore, the plate members 501 are arranged at predetermined intervals in the same direction perpendicular to the first direction D1 (radial direction). Therefore, gaps are provided between the plate members 501. The gas conductance is maintained by these gaps.

[0046] On the other hand, when viewed from the first direction D1, two adjacent plate members of the plate members 501 partially overlap each other, and no gap is visible between the two adjacent plate members 501. For example, when viewed from the first direction D1, the upper end E1 of the first plate member 501a in the arrangement direction of the plate members 501 is located higher than the lower end E2 of the second plate member 501b adjacent to the first plate member 501a. Therefore, when viewed from the first direction D1, the first plate member 501a and the second plate member 501b overlap each other, and no gap is visible between them. The other plate members 501 are arranged in the same manner, and when viewed from the first direction D1, the multiple plate members 501 are arranged with partial overlaps, and no gap is visible between them. In this way, the multiple plate members 501 are arranged so that no gap is visible when viewed from the first direction D1 while maintaining the gas conductance. This allows the plate member 501 to effectively block the positive ions P that attempt to move from the ion pump 117 to the electron gun chamber 217 .

[0047] The conductive frame 502 serving as a frame material is electrically connected to the plurality of plate members 501 and the feed-through terminal 550. The conductive frame 502 electrically connects the plurality of plate members 501 to each other. The conductive frame 502 also fixes the plurality of plate members 501 to the connection tube 400, the electron gun chamber 217, and the ion pump 117. The plurality of plate members 501 are fixed by the conductive frame 502 in a state where they are arranged with almost no gaps when viewed from the first direction D1. The conductive frame 502 is made of a material having electrical conductivity and corrosion resistance, such as SUS.

[0048] An insulating sleeve 503 as an insulating part is provided on the outer periphery of the conductive frame 502. The insulating sleeve 503 is provided so that no gap is generated between the inner wall of the connection pipe 400 and the conductive frame 502 when the shield 500 is attached inside the connection pipe 400. Therefore, the insulating sleeve 503 is made of a material having insulating properties and corrosion resistance, such as ceramic. The insulating sleeve 503 may also be made of a high resistance material, such as ceramic with a small amount of metal, such as titanium, introduced therein.

[0049] The insulating sleeve 503 electrically isolates the multiple plate members 501 and the conductive frame 502 from the connecting tube 400, the electron gun chamber 217, and the ion pump 117. Therefore, the shield 500 is electrically insulated from the connecting tube 400, the electron gun chamber 217, and the ion pump 117 by the insulating sleeve 503, and is in an electrically floating state. Furthermore, when the insulating sleeve 503 is made of a high resistance material in which a small amount of metal such as titanium is introduced into ceramic, charging of the insulating sleeve 503 can be suppressed.

[0050] The conductive frame 502 is electrically connected to the ammeter 560 via the wiring 570 and the feed-through terminal 550. This allows the ammeter 560 to measure the ion current that flows when ions collide with the plate member 501.

[0051] The ammeter 560 includes a monitor 561 as a display unit. The monitor 561 displays the current value flowing through the shield 500 measured by the ammeter 560. This allows the operator to know the amount of ions flowing back from the ion pump 117 to the electron gun chamber 217. The conductive frame 502 and the multiple plate members 501 of the shield 500 are electrically floating by the insulating sleeve 503. Therefore, the ions that have reached the multiple plate members 501 can be measured by the ammeter 560 as a current through the conductive frame 502, the wiring 570, and the feed-through terminal 550. This allows the amount of ions flowing back from the ion pump 117 to the electron gun chamber 217 to be determined from the current value flowing through the shield 500. That is, the ammeter 560 can measure the amount of ions that have reached the shield 500 by the current flowing through the shield 500.

[0052] The ammeter 560 periodically measures the value of the current flowing through the shield 500 and periodically grasps the amount of ions flowing back from the ion pump 117 to the electron gun chamber 217. The ammeter 560 determines the time to replace the ion pump 117 from the transition of this current value. For example, the ammeter 560 may determine that it is time to replace the ion pump 117 when the value of the current flowing through the shield 500 increases n times (n is an integer of 2 or more) consecutively, and display that fact on the monitor 561. The ammeter 560 may determine that it is time to replace the ion pump 117 when the value of the current flowing through the shield 500 becomes equal to or greater than a predetermined threshold, and display that fact on the monitor 561. This allows the operator to properly replace the ion pump 117 before discharge occurs in the electron gun chamber 217. That is, the operator can determine the appropriate time to replace the ion pump 117.

[0053] Furthermore, when scattered electrons generated at the cathode electrode of the electron gun 201 reach the shield 500, the ammeter 560 can also measure the amount of scattered electrons.

[0054] Furthermore, when a discharge occurs in the electron gun chamber 217, the ammeter 560 can also measure the noise (current) caused by the discharge.

[0055] In this manner, the apparatus 100 according to the present embodiment measures the ion current flowing through the shield 500, which is in an electrically floating state, by the ammeter 560. As a result, the ammeter 560 periodically measures the amount of ions flowing back from the ion pump 117 to the electron gun chamber 217. By checking the trend of the amount of ions flowing back, the apparatus 100 can inform the operator of the time to replace the ion pump 117 before discharge occurs in the electron gun chamber 217. In other words, the apparatus 100 can determine the appropriate time to replace the ion pump 117. As a result, the operator can replace the ion pump 117 at the appropriate time, and the occurrence of discharge in the electron gun chamber 217 can be suppressed.

[0056] (Variation 1) 5 is a cross-sectional view showing a configuration example of a shield 500 according to Modification 1. According to this modification, the shield 500 includes a mesh member 505 instead of the plate member 501. The mesh member 505 is provided on the entire inside of the conductive frame 502. The mesh member 505 is made of a material having electrical conductivity and corrosion resistance, such as SUS.

[0057] The mesh member 505 has good gas conductance. On the other hand, when the mesh member 505 is viewed from the first direction D1, the other side of the shield 500 is somewhat visible. In this case, the mesh member 505 can block the passage of the positive ions P to a certain extent, although not to the same extent as the plate member 501.

[0058] The mesh member 505 is also electrically connected to the conductive frame 502, and is electrically connected to the ammeter 560 via the wiring 570 and the feed-through terminal 550. This allows the ammeter 560 to measure the ion current that flows when ions collide with the mesh member 505. Therefore, this modification can obtain the same effects as the first embodiment.

[0059] (Variations 2 and 3) Fig. 6 is a cross-sectional view showing a configuration example of a shield 500 according to Modification 2. According to the modification of Fig. 6, the multiple plate members 501 each have a substantially U-shape in a cross section perpendicular to the extension direction of the plate members 501 within the conductive frame 502.

[0060] Fig. 7 is a cross-sectional view showing a configuration example of a shield 500 according to Modification 3. According to the modification of Fig. 7, the multiple plate members 501 have a generally flat plate shape arranged so as to be inclined with respect to the first direction D1 in a cross section perpendicular to the extension direction of the plate members 501 within the conductive frame 502.

[0061] 6 and 7, if two adjacent plate members 501 partially overlap when viewed from the first direction D1, the plate members 501 can effectively block the positive ions P attempting to move from the ion pump 117 to the electron gun chamber 217. On the other hand, the multiple plate members 501 are spaced apart from each other, and therefore have good gas conductance.

[0062] The multiple plate members 501 are electrically connected to the conductive frame 502, and are electrically connected to the ammeter 560 via the wiring 570 and the feed-through terminal 550. This allows the ammeter 560 to measure the ion current that flows when ions collide with the mesh member 505. Therefore, this modified example can also obtain the same effects as the first embodiment.

[0063] For example, a portion of the shield 500 may be made of the plate member 501, and the other portion may be made of the mesh member 505.

[0064] (Variation 4) The ammeter 560 as a measuring device may measure the current flowing through the shield 500 and may apply a DC voltage to the shield 500 as a DC voltage source. That is, the ammeter 560 may be a voltage application type ammeter. In this case, the ammeter 560 can measure the amount of ions flowing back from the ion pump 117 and the amount of scattered electrons from the electron gun chamber 217 independently by applying a DC voltage to the shield 500. For example, the ammeter 560 applies a negative voltage to the shield 500 to eliminate the scattered electrons from the electron gun chamber 217 and measure the amount of positive ions flowing back from the ion pump 117. On the other hand, the ammeter 560 applies a positive voltage to the shield 500 to eliminate the positive ions from the ion pump 117 and measure the amount of scattered electrons from the electron gun chamber 217. This allows the ammeter 560 to accurately measure the amount of ions flowing back from the ion pump 117 and the amount of scattered electrons from the electron gun chamber 217 independently.

[0065] The ammeter 560 may be attached externally as a separate unit from the device 100. In this case, the charged particle beam device 100 includes an ion pump 117 as a pressure reducing device that ionizes the gas in the electron gun chamber 217 as a chamber to reduce the pressure inside the electron gun chamber 217, a connecting pipe 400 that connects the electron gun chamber 217 and the ion pump 117, and a shield 500 that is provided in the connecting pipe 400, is in an electrically floating state, and serves as a shielding member that blocks ions flowing from the ion pump 117 to the electron gun chamber 217. The ammeter 560 is attached to the charged particle beam device 100 and electrically connected to the shield 500, and functions as a current measuring device that measures the ion current of the shield 500.

[0066] The current measuring device is The ammeter 560, A feed-through terminal 550 provided to penetrate the wall of any one of the electron gun chamber 217, the ion pump 117, or the connecting tube 400; Wiring 570 may be electrically connected between the shield 500 and the ammeter 560 through the feed-through terminal 550 .

[0067] In this case, the ammeter 560, the feed-through terminal 550 and the wiring 570 can be easily replaced.

[0068] Furthermore, the current measuring device The ammeter 560, The feedthrough terminal 550, The wiring 570, A shield 500 may be provided in the connection tube 400 as a shielding member that is in an electrically floating state and blocks ions flowing from the ion pump 117 to the electron gun chamber 217 .

[0069] In this case, the ammeter 560, the feedthrough terminal 550, the wiring 570 and the shield 500 can be easily replaced.

[0070] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents described in the claims, as well as in the scope and spirit of the invention. [Explanation of symbols]

[0071] 100 Charged particle beam device 150 Drawing section 160 Control and calculation section 217 Electron Gun Room 201 Electron Gun 117 Ion Pump 400 Connecting pipe 500 Shield 501 Plate members 502 Conductive frame 503 Insulating Sleeve 505 Mesh material 550 Feedthrough Terminal 560 ammeter 570 Wiring

Claims

1. a charged particle generating unit that generates charged particles; a chamber that accommodates the charged particle generator; a pressure reducing device that ionizes the gas in the chamber to reduce the pressure inside the chamber; a connecting pipe connecting the chamber and the pressure reducing device; a shielding member provided in the connecting pipe, in an electrically floating state, for blocking ions flowing from the pressure reducing device to the chamber; a measuring device electrically connected to the shielding member for measuring an electrical change in the shielding member.

2. a feedthrough terminal provided to penetrate a wall of any one of the chamber, the pressure reducing device, or the connecting pipe; The charged particle beam device according to claim 1 , further comprising a wiring electrically connected between the shielding member and the measuring device through the feedthrough terminal.

3. The charged particle beam device according to claim 2 , wherein the measuring device is provided outside the chamber and is electrically connected to the shielding member via the feedthrough terminal.

4. The charged particle beam device according to claim 1 , wherein the measuring device applies a voltage to the shielding member.

5. 3. The charged particle beam device according to claim 2, wherein the wiring is covered with an insulating material outside the chamber, the pressure reduction device, or the connecting pipe, and is not covered with the insulating material inside the chamber, the pressure reduction device, or the connecting pipe.

6. The shielding member is A plurality of conductive members made of a conductive material; a frame member made of a conductive material, electrically connected to the plurality of conductive members and the wiring, and fixing positions of the plurality of conductive members with respect to the connection pipe; 3. The charged particle beam device according to claim 2, further comprising an insulating portion made of an insulating material and provided between said connection pipe and said frame material.

7. the frame member electrically connects the plurality of conductive members to the wiring; 7. The charged particle beam device according to claim 6, wherein the insulating section electrically isolates the frame and the plurality of conductive members from the chamber, the pressure reducing device, and the connecting pipes.

8. 2. The charged particle beam device according to claim 1, wherein the measuring device measures an amount of ions that have reached the shielding member by a current flowing through the shielding member.

9. The charged particle beam device according to claim 6 , wherein the insulating member is made of ceramic or ceramic containing a metal.

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