Ion implantation apparatus and electrostatic quadrupole lens apparatus

Abstract

The present application can inhibit dirt from adhering to an electrode body included in an electrostatic quadrupole lens device or an insulating member supporting the electrode body, to improve the vacuum degree of a beam line. The electrostatic quadrupole lens device includes: a plurality of lens electrodes (82) opposed in a radial direction orthogonal to an axial direction in which a beam line (BL) extends, with the beam line (BL) interposed therebetween, and arranged with a gap interposed therebetween in a circumferential direction orthogonal to both the axial and radial directions; an upstream-side cover electrode (84a) covering a beam line upstream side of the plurality of lens electrodes (82) and having a beam entrance port (92a) opened in the axial direction; and a downstream-side cover electrode (84b) covering a beam line downstream side of the plurality of lens electrodes (82) and having a beam exit port (92b) opened in the axial direction. At least one of the upstream-side cover electrode (84a) and the downstream-side cover electrode (84b) has at least one gas discharge port (94a, 94b, 96a, 96b) opened in the radial direction.

Description

Technical Field

[0001] This application claims priority based on Japanese Patent Application No. 2021-032815, filed on March 2, 2021. The entire contents of that Japanese application are incorporated herein by reference.

[0002] This invention relates to an ion implantation device and an electrostatic quadrupole lens device. Background Technology

[0003] In semiconductor manufacturing processes, a standard procedure is performed to implant ions into semiconductor wafers (also known as ion implantation) to alter the conductivity or crystal structure of the semiconductor. The apparatus used in this process is called an ion implantation apparatus. The implantation energy is determined based on the desired implantation depth of the ions implanted near the wafer surface. Higher energy (e.g., 1 MeV or higher) ion beams are used for deeper implantations.

[0004] In ion implantation devices capable of outputting high-energy ion beams, a multi-stage high-frequency linear accelerator (LINAC) is used to accelerate the ion beam. The high-frequency linear accelerator includes, for example, a multi-stage high-frequency accelerating section for accelerating the ion beam and a multi-stage electrostatic quadrupole lens electrode for converging the ion beam.

[0005] Patent Document 1: US Patent No. 5,504,341

[0006] Recently, ultra-high energy (e.g., above 4 MeV) ion beams have been required to penetrate deeper regions. To generate ultra-high energy ion beams, it is necessary to further increase the accelerating voltage applied to the high-frequency accelerating section, and also to further increase the focusing / diverging voltage applied to the lens electrodes. If the voltage applied to the lens electrodes increases, discharge between the electrodes is more likely to occur. In particular, if the ion beam collides with electrode bodies such as the lens electrodes, causing sputtering, the sputtered material adheres to the electrode bodies or the insulating components supporting the electrode bodies, contaminating them, further increasing the likelihood of discharge. Furthermore, sometimes multivalent ions are used to generate ultra-high energy ion beams; if the vacuum level of the beamline decreases, the multivalent ions often experience a decrease in valence due to interaction with the gas remaining in the beamline. Summary of the Invention

[0007] An exemplary objective of one embodiment of the present invention is to provide a technique for improving the vacuum level of a beamline by inhibiting the adhesion of dirt to the insulating components of the electrode body or supporting electrode body included in an electrostatic quadrupole lens device.

[0008] An ion implantation apparatus according to one embodiment of the present invention includes a high-energy multi-stage linear acceleration unit for accelerating an ion beam. The high-energy multi-stage linear acceleration unit comprises: a multi-stage high-frequency acceleration section disposed along the beamline of the ion beam; and a multi-stage electrostatic quadrupole lens device disposed along the beamline. Each stage of the electrostatic quadrupole lens device includes: a plurality of lens electrodes spaced apart by the beamline, facing each other radially orthogonal to the axial direction extending from the beamline, and spaced apart circumferentially orthogonal to both the axial and radial directions; an upstream covering electrode covering the upstream side of the beamline of the plurality of lens electrodes and having a beam inlet open in the axial direction; and a downstream covering electrode covering the downstream side of the beamline of the plurality of lens electrodes and having a beam outlet open in the axial direction. At least one of the upstream and downstream covering electrodes included in at least one stage of the multi-stage electrostatic quadrupole lens device has at least one gas outlet open in the radial direction.

[0009] Another embodiment of the present invention is an electrostatic quadrupole lens device. This device includes: a plurality of lens electrodes, with a beamline spaced between opposing lens electrodes, facing each other radially orthogonal to the axis extending from the beamline, and spaced apart circumferentially in both the axial and radial directions; an upstream covering electrode covering the upstream side of the beamline of the plurality of lens electrodes and having a beam inlet open in the axial direction; and a downstream covering electrode covering the downstream side of the beamline of the plurality of lens electrodes and having a beam outlet open in the axial direction. At least one of the upstream and downstream covering electrodes has at least one gas outlet open in the radial direction.

[0010] Furthermore, any combination of the above-mentioned constituent elements or the constituent elements or expressions of the present invention that can be substituted for each other in the method, apparatus, system, etc., is equally effective as an embodiment of the present invention.

[0011] Invention Effects

[0012] According to one embodiment of the present invention, it is possible to suppress the adhesion of dirt to the insulating components of the electrode body or the supporting electrode body included in the electrostatic quadrupole lens device, thereby improving the vacuum degree of the beamline. Attached Figure Description

[0013] Figure 1 This is a top view showing the general structure of the ion implantation apparatus according to the embodiment.

[0014] Figure 2 (a)~ Figure 2 (c) is a cross-sectional view showing the schematic structure of the linear acceleration device.

[0015] Figure 3 (a) Figure 3(b) is a front view showing the general structure of the electrostatic quadrupole lens device.

[0016] Figure 4 A cross-sectional view showing the general structure of the high-frequency acceleration unit.

[0017] Figure 5 A cross-sectional view showing the structure of the linear acceleration device according to the embodiment in detail.

[0018] Figure 6 This is a cross-sectional view showing the configuration of the vacuum chamber according to the embodiment.

[0019] Figure 7 This is a perspective view showing an example of the appearance of a lens unit as viewed from the upstream side.

[0020] Figure 8 To indicate the view from the downstream side Figure 7 A three-dimensional view of the lens unit.

[0021] Figure 9 To show in detail Figure 7 A cross-sectional view of the beamline of the internal structure of the lens unit.

[0022] Figure 10 To show in detail Figure 7 A cross-sectional view of the beamlines of the internal structure of the lens unit.

[0023] In the diagram: 14-beam acceleration unit, 70-high frequency acceleration section, 72-high frequency electrode, 74-high frequency resonator, 76-rod, 80-lens unit, 82-lens electrode, 84a-upstream side cover electrode, 84b-downstream side cover electrode, 86-base plate, 88-mounting part, 88a, 88b-notches, 90-insulating component, 92a-beam inlet, 92b-beam outlet, 94a, 94b-first gas outlet, 95a, 95b-second gas outlet, 96a, 96b-third gas outlet, 100-ion implantation device, 101-115-high frequency acceleration section, 121-139-electrostatic quadrupole lens device, 140-vacuum tank, 148-vacuum exhaust device. Detailed Implementation

[0024] Hereinafter, the embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. Furthermore, the same symbols are used to denote the same elements in the description of the drawings, and repeated descriptions are omitted. Also, the structures described below are examples and do not limit the scope of the present invention in any way.

[0025] Before detailing the implementation method, a general overview is provided. This embodiment relates to a high-energy ion implantation apparatus. The ion implantation apparatus accelerates an ion beam generated at an ion source using a high-frequency linear accelerator, and then delivers the high-energy ion beam obtained after acceleration along a beamline to the workpiece (e.g., a substrate or wafer) to implant ions into the workpiece. Furthermore, in the following description, for ease of understanding, "workpiece (e.g., substrate or wafer)" will be described as "wafer," but the ion implantation method and ion implantation apparatus of the present invention are not limited thereto. For example, specific examples of "workpiece (e.g., substrate or wafer)" include not only semiconductor wafers, but also flat panel display substrates (e.g., glass substrates).

[0026] In this embodiment, "high energy" refers to an ion beam with a beam energy of 1 MeV or higher, 4 MeV or higher, or 10 MeV or higher. With high-energy ion implantation, desired impurity ions are implanted into the wafer surface at relatively high energy, thus enabling the implantation of desired impurities into deeper regions of the wafer surface (e.g., depths of 5 μm or higher). Applications of high-energy ion implantation include, for example, forming P-type and / or N-type regions in the fabrication of semiconductor devices such as state-of-the-art image sensors.

[0027] The high-frequency linear accelerator includes a multi-stage high-frequency accelerating section for accelerating an ion beam and a multi-stage electrostatic quadrupole lens for focusing the ion beam. The electrostatic quadrupole lens assembly includes: multiple lens electrodes facing each other across a beamline; an upstream covering electrode covering the upstream side of the beamline of the multiple lens electrodes; and a downstream covering electrode covering the downstream side of the beamline of the multiple lens electrodes. Each of the upstream and downstream covering electrodes has a beam passage port for the ion beam to pass through and also functions as a grounding electrode.

[0028] To generate higher-energy ion beams, it is necessary to further increase the accelerating voltage applied to the high-frequency accelerating section and the converging / diverging voltage applied to the lens electrodes. If the voltage applied to the lens electrodes increases, discharge is more likely to occur between the lens electrodes and the cover electrodes. Since the electrode bodies of the lens electrodes or cover electrodes are positioned close to the beamline, they are sputtered due to collisions with the ion beam. If the sputtered material adheres to the insulating components of the electrode bodies or support electrodes, contaminating these components, discharge between the electrode bodies is more likely to occur. Furthermore, the space between the upstream and downstream cover electrodes of each electrostatic quadrupole lens device easily traps sputtered material, creating an environment prone to contamination of the insulating components of the electrode bodies or support electrodes.

[0029] In this embodiment, by providing a gas outlet at the cover electrode of the electrostatic quadrupole lens device, the sputtered material can be easily discharged to the outside of the cover electrode through the gas outlet. Furthermore, by providing the gas outlet, the vacuum level of the space between the upstream and downstream cover electrodes of each electrostatic quadrupole lens device, i.e., the vacuum level of the beamline of the high-frequency linear accelerator, is increased. Sometimes, multivalent ions are used to generate higher-energy ion beams, but multivalent ions have the characteristic that their valence decreases when they interact with the gas remaining in the beamline. In particular, the higher the valence of the ion, the easier it is for it to interact with the residual gas. According to this embodiment, by providing a gas outlet at the cover electrode, the residual gas in the beamline can be reduced, thereby suppressing the decrease in beam current due to the reduction of multivalent ions.

[0030] Figure 1 The top view of the ion implantation apparatus 100 according to the embodiment is shown in a schematic diagram. The ion implantation apparatus 100 includes a beam generation unit 12, a beam acceleration unit 14, a beam deflection unit 16, a beam delivery unit 18, and a substrate transfer processing unit 20.

[0031] The beam generation unit 12 includes an ion source 10 and a mass spectrometry analyzer 11. In the beam generation unit 12, an ion beam is drawn from the ion source 10 and subjected to mass spectrometry analysis by the mass spectrometry analyzer 11. The mass spectrometry analyzer 11 includes a mass spectrometry magnet 11a and a mass spectrometry slit 11b. The mass spectrometry slit 11b is positioned downstream of the mass spectrometry magnet 11a. Based on the results of the mass spectrometry analysis by the mass spectrometry analyzer 11, only the desired ion species are selected for implantation, and the ion beams of the selected ion species are guided to the next beam acceleration unit 14.

[0032] The beam acceleration unit 14 includes multiple linear acceleration devices 22a, 22b, and 22c for accelerating an ion beam and a beam measurement unit 23, forming a linearly extending portion of the beamline BL. Each of the multiple linear acceleration devices 22a to 22c has at least one high-frequency acceleration unit and applies a high-frequency (RF) electric field to the ion beam to accelerate it. The beam measurement unit 23 is located at the downstream end of the beam acceleration unit 14 and measures at least one beam characteristic of the high-energy ion beam accelerated by the multiple linear acceleration devices 22a to 22c. The beam measurement unit 23 measures beam energy, beam current, beam distribution, etc., as beam characteristics of the ion beam. In this specification, the beam acceleration unit 14 is also referred to as a "high-energy multi-stage linear acceleration unit".

[0033] In this embodiment, three linear acceleration devices 22a to 22c are provided. The first linear acceleration device 22a is located at the upper stage of the beam acceleration unit 14 and includes multiple stages (e.g., 5 to 15 stages) of high-frequency acceleration. The first linear acceleration device 22a performs "bunching," aligning the continuous beam (DC beam) output from the beam generation unit 12 to a specific acceleration phase, for example, accelerating the ion beam to an energy of approximately 1 MeV. The second linear acceleration device 22b is located at the middle stage of the beam acceleration unit 14 and includes multiple stages (e.g., 5 to 15 stages) of high-frequency acceleration. The second linear acceleration device 22b accelerates the ion beam output from the first linear acceleration device 22a to an energy of, for example, approximately 2 to 3 MeV. The third linear acceleration device 22c is located at the lower stage of the beam acceleration unit 14 and includes multiple stages (e.g., 5 to 15 stages) of high-frequency acceleration. The third linear accelerator 22c accelerates the ion beam output from the second linear accelerator 22b to high energies, for example, above 4 MeV.

[0034] The high-energy ion beam output from the beam acceleration unit 14 has a certain range of energy distribution. Therefore, in order to reciprocate and scan the high-energy ion beam downstream of the beam acceleration unit 14 and parallelize it to irradiate the wafer, it is necessary to perform high-precision energy analysis, energy dispersion control, trajectory correction, and beam convergence and divergence adjustment in advance.

[0035] The beam deflection unit 16 performs energy analysis, energy dispersion control, and trajectory correction of the high-energy ion beam output from the beam acceleration unit 14. The beam deflection unit 16 constitutes the arc-shaped extension of the beamline BL. The high-energy ion beam undergoes direction conversion through the beam deflection unit 16 and is directed toward the beam delivery unit 18.

[0036] The beam deflection unit 16 includes an energy analysis electromagnet 24, a lateral converging quadrupole lens 26 to suppress energy dispersion, an energy analysis slit 27, a first Faraday cup 28, a deflection electromagnet 30 to provide steering (track correction), and a second Faraday cup 31. The energy analysis electromagnet 24 is also referred to as an energy filtering electromagnet (EFM). Furthermore, the assembly consisting of the energy analysis electromagnet 24, the lateral converging quadrupole lens 26, the energy analysis slit 27, and the first Faraday cup 28 is collectively referred to as an "energy analysis device".

[0037] The energy analysis slit 27 can be configured with a variable slit width to adjust the resolution of the energy analysis. The energy analysis slit 27 may be composed of two shielding bodies capable of moving in the slit width direction, and the slit width can be adjusted by changing the interval between the two shielding bodies. The energy analysis slit 27 can also be configured to have a variable slit width by selecting any one of a plurality of slits with different widths.

[0038] The first Faraday cup 28 is positioned immediately behind the energy analysis slit 27 and is used for measuring the beam current for energy analysis. The second Faraday cup 31 is positioned immediately behind the deflecting electromagnet 30 and is configured to measure the beam current of the ion beam entering the beam delivery unit 18 after trajectory correction. Both the first Faraday cup 28 and the second Faraday cup 31 are configured to move in and out of the beam line BL via the operation of the Faraday cup drive unit (not shown).

[0039] The beam delivery unit 18 forms another straight extension of the beamline BL, and runs parallel to the beam acceleration unit 14 across the maintenance area MA in the center of the device. The length of the beam delivery unit 18 is designed to be approximately the same as the length of the beam acceleration unit 14. As a result, the beamline BL, composed of the beam acceleration unit 14, the beam deflection unit 16, and the beam delivery unit 18, forms a U-shaped layout.

[0040] The beam delivery unit 18 includes a beam shaper 32, a beam scanner 34, a beam collector 35, a beam parallelizer 36, a final energy filter 38, and left and right Faraday cups 39L and 39R.

[0041] The beam shaper 32 includes converging / diverging lenses such as quadrupole lenses (Q lenses) and is configured to shape the ion beam passing through the beam deflection unit 16 into a desired cross-sectional shape. The beam shaper 32 may be constructed, for example, by an electric field-type triple quadrupole lens (also called a triple Q lens) and has three electrostatic quadrupole lenses. By using the three lens devices, the beam shaper 32 can independently adjust the convergence or divergence of the ion beam in both the horizontal (x-direction) and vertical (y-direction) directions. The beam shaper 32 may include magnetic field lenses, or it may include lenses that utilize both electric and magnetic fields to shape the beam.

[0042] The beam scanner 34 is a beam deflection device configured to provide reciprocating scanning of the beam and to scan the shaped ion beam in the x-direction. The beam scanner 34 has a pair of scanning electrodes facing each other in the beam scanning direction (x-direction). The scanning electrode pair is connected to a variable voltage power supply (not shown), and by periodically changing the voltage applied between the scanning electrode pair, the electric field generated between the electrodes is changed, thereby deflecting the ion beam at various angles. As a result, the ion beam scans throughout the scanning range indicated by arrow X. Figure 1 In the diagram, multiple trajectories of the ion beam within the scanning range are represented by thin solid lines. Furthermore, the beam scanner 34 can be replaced with other beam scanning devices, which can also be configured as a magnet device utilizing a magnetic field.

[0043] The beam scanner 34 directs the ion beam to a beam collector 35 located away from the beam line BL by deflecting the beam beyond the scanning range indicated by arrow X. The beam scanner 34 blocks the ion beam by temporarily avoiding the beam line BL by directing the ion beam toward the beam collector 35, thus preventing the ion beam from reaching the downstream substrate transfer processing unit 20.

[0044] The beam parallelizer 36 is configured to make the travel direction of the scanned ion beam parallel to the designed trajectory of the beam line BL. The beam parallelizer 36 has multiple arc-shaped parallelizing lens electrodes with the ion beam passing through a slit at the center. The parallelizing lens electrodes are connected to a high-voltage power supply (not shown), and an electric field generated by the applied voltage is applied to the ion beam to achieve parallelism in its travel direction. Alternatively, the beam parallelizer 36 can be replaced with other beam parallelizing devices, which can also be configured as a magnetic device utilizing a magnetic field.

[0045] The final energy filter 38 is configured to analyze the energy of the ion beam and deflect ions of the required energy downwards (in the -y direction) to guide them to the substrate transport processing unit 20. The final energy filter 38 is sometimes referred to as an angle energy filter (AEF) and has an AEF electrode pair for electric field deflection. The AEF electrode pair is connected to a high-voltage power supply (not shown). By applying a positive voltage to the upper AEF electrode and a negative voltage to the lower AEF electrode, the ion beam is deflected downwards. Alternatively, the final energy filter 38 can be constructed from a magnetic field deflection magnet device, or from a combination of the electric field deflection AEF electrode pair and the magnetic field deflection magnet device.

[0046] The left and right Faraday cups 39L and 39R are located downstream of the final energy filter 38 and positioned at the left and right ends of the scanning range indicated by arrow X, where the beam can enter. The left and right Faraday cups 39L and 39R are positioned so as not to obstruct the beam directed toward the wafer W, and the beam current is measured during ion implantation of the wafer W.

[0047] A substrate transfer processing unit 20 is provided downstream of the beam delivery unit 18, i.e., at the very downstream of the beam line BL. The substrate transfer processing unit 20 includes an implantation processing chamber 40, a beam monitor 41, a beam analyzer 42, an analyzer drive 43, a substrate transfer device 44, and a loading port 46. A platform drive device (not shown) is provided in the implantation processing chamber 40 to hold the wafer W during ion implantation and move the wafer W in a direction orthogonal to the beam scanning direction (x direction) (y direction).

[0048] A beam monitor 41 is located at the downstream end of the beamline BL inside the implantation processing chamber 40. The beam monitor 41 is positioned at the point where the ion beam can be incident when there is no wafer W on the beamline BL, and is configured to measure beam characteristics before or during the ion implantation process. The beam monitor 41 measures beam current, beam parallelism, etc., as beam characteristics. For example, the beam monitor 41 is located near the transfer port (not shown) connecting the implantation processing chamber 40 and the substrate transfer device 44, and is positioned vertically below the transfer port.

[0049] The beam analyzer 42 is configured to measure the beam current at a position on the surface of the wafer W. The beam analyzer 42 is configured to move in the x-direction via the action of the analyzer drive device 43, avoiding the implantation position of the wafer W during ion implantation and inserting into the implantation position when the wafer W is not in the implantation position. By measuring the beam current while moving in the x-direction, the beam analyzer 42 can measure the beam current across the entire beam scanning range in the x-direction. The beam analyzer 42 may have multiple Faraday cups arranged in an array in the x-direction to simultaneously measure the beam current at multiple positions in the beam scanning direction (x-direction).

[0050] The beam analyzer 42 may include a single Faraday cup for measuring the beam current, or an angle measuring device for measuring the beam's angle information. The angle measuring device may include, for example, a slit and multiple current detection units disposed away from the slit in the beam travel direction (z-direction). The angle measuring device, for example, measures the beam passing through the slit using multiple current detection units arranged in the slit width direction, and can determine the angular component of the beam in the slit width direction. The beam analyzer 42 may include a first angle measuring device capable of measuring angle information in the x-direction and a second angle measuring device capable of measuring angle information in the y-direction.

[0051] The substrate transfer device 44 is configured to transfer wafers W between the loading port 46 of the wafer container 45 and the implantation processing chamber 40. The loading port 46 is configured to simultaneously hold multiple wafer containers 45, for example, having four loading stages arranged in the x-direction. A wafer container transfer port (not shown) is provided vertically above the loading port 46 and is configured to allow wafer containers 45 to pass through in the vertical direction. The wafer containers 45 are automatically moved into the loading port 46 through the wafer container transfer port, for example, by a handling robot installed on the ceiling or the like in a semiconductor manufacturing plant where the ion implantation device 100 is installed, and are automatically moved out of the loading port 46.

[0052] The ion implantation apparatus 100 also includes a central control unit 50. The central control unit 50 controls the overall operation of the ion implantation apparatus 100. The central control unit 50 is implemented in hardware through components and mechanical devices, such as a computer's CPU and memory, and in software through computer programs. The various functions provided by the central control unit 50 can be achieved through the cooperation of hardware and software.

[0053] An operation panel 49 is provided near the central control unit 50. This operation panel 49 has a display device and an input device for setting the operating parameters of the ion implantation apparatus 100. The positions of the operation panel 49 and the central control unit 50 are not particularly limited; for example, they can be positioned adjacent to the entrance / exit 48 of the maintenance area MA between the beam generation unit 12 and the substrate transfer processing unit 20. By placing the ion source 10, loading port 46, operation panel 49, and central control unit 50—areas where operators of the ion implantation apparatus 100 perform high-frequency operations—adjacently, operational efficiency can be improved.

[0054] Next, the detailed structure of the beam acceleration unit 14 will be explained. Figure 2 (a)~ Figure 2 (c) is a cross-sectional view showing the structure of the linear acceleration devices 22a to 22c. Figure 2 (a) shows the structure of the first linear acceleration device 22a. Figure 2 (b) shows the structure of the second linear acceleration device 22b. Figure 2 (c) indicates the structure of the third linear accelerator 22c. Linear accelerators 22a to 22c include multi-stage high-frequency accelerating units 101 to 115 arranged along the beamline BL and multi-stage electrostatic quadrupole lens devices 121 to 139 arranged along the beamline BL. At least one stage of electrostatic quadrupole lens device is arranged on the upstream and downstream sides of each stage of the high-frequency accelerating units 101 to 115.

[0055] The high-frequency acceleration section applies a high-frequency voltage V to the high-frequency electrodes through which the ion beam IB passes. RF This accelerates or decelerates the ion particles that constitute the ion beam IB. Each stage of the high-frequency acceleration unit is configured to individually adjust the high-frequency voltage V. RF The voltage amplitude V0, frequency f, and phase φ. In this specification, sometimes the high-frequency voltage V... RF The voltage amplitude V0, frequency f, and phase φ are collectively referred to as "high-frequency parameters".

[0056] The electrostatic quadrupole lens device includes lens electrodes for applying an electrostatic field to the ion beam IB to converge or diverge the ion beam IB, and ground electrodes disposed upstream and downstream of the lens electrodes. By switching the polarity of the voltage applied to the lens electrodes, the electrostatic quadrupole lens device functions as a lateral converging (longitudinal diverging) lens for converging the beam in the x-direction or a longitudinal converging (lateral diverging) lens for converging the beam in the y-direction.

[0057] exist Figure 2 (a)~ Figure 2 In (c), the diagram shows the lens electrodes facing each other in the y-direction, while the lens electrodes facing each other in the x-direction are omitted. If a negative voltage is applied to the lens electrodes facing each other in the y-direction, it functions as a lateral converging (longitudinal diverging) lens. Conversely, if a positive voltage is applied to the lens electrodes facing each other in the y-direction, it functions as a longitudinal converging (lateral diverging) lens. For the structure of the lens electrodes, refer to [reference needed]. Figure 3 (a) Figure 3 (b) will be described separately later.

[0058] The first linear accelerator 22a includes five high-frequency accelerating sections 101, 102, 103, 104, and 105, and seven electrostatic quadrupole lens devices 121, 122, 123, 124, 125, 126, and 127. The first and second stage electrostatic quadrupole lens devices 121 and 122 are continuously arranged at the inlet of the first linear accelerator 22a. The third to seventh stage electrostatic quadrupole lens devices 123 to 127, excluding the first and second stages, are each arranged downstream of each of the first to fifth stage high-frequency accelerating sections 101 to 105.

[0059] The 7-stage electrostatic quadrupole lens devices 121-127 installed in the first linear accelerator 22a are configured such that lateral converging lenses and longitudinal converging lenses alternate along the beamline BL. For example, the 1st, 3rd, 5th, and 7th stage electrostatic quadrupole lens devices 121, 123, 125, and 127 are longitudinal converging lenses, while the 2nd, 4th, and 6th stage electrostatic quadrupole lens devices 122, 124, and 126 are lateral converging lenses.

[0060] The second linear accelerator 22b includes five high-frequency accelerating sections 106, 107, 108, 109, and 110, and six electrostatic quadrupole lens devices 128, 129, 130, 131, 132, and 133. Except for the eighth-stage electrostatic quadrupole lens device 128 located at the entrance of the second linear accelerator 22b, the ninth to thirteenth-stage electrostatic quadrupole lens devices 129 to 133 are each located downstream of each of the sixth to tenth-stage high-frequency accelerating sections 106 to 110. The six-stage electrostatic quadrupole lens devices 128 to 133 located in the second linear accelerator 22b are configured such that lateral converging lenses and longitudinal converging lenses alternate along the beamline BL. For example, the 8th, 10th, and 12th level electrostatic quadrupole lens devices 128, 130, and 132 are lateral converging lenses, while the 9th, 11th, and 13th level electrostatic quadrupole lens devices 129, 131, and 133 are longitudinal converging lenses.

[0061] The third linear accelerator 22c includes five high-frequency accelerating sections 111, 112, 113, 114, and 115, and six electrostatic quadrupole lens devices 134, 135, 136, 137, 138, and 139. Except for the fourteenth-stage electrostatic quadrupole lens device 134 located at the entrance of the third linear accelerator 22c, the fifteenth to nineteenth-stage electrostatic quadrupole lens devices 135 to 139 are each located downstream of each of the eleventh to fifteenth-stage high-frequency accelerating sections 111 to 115. The six-stage electrostatic quadrupole lens devices 134 to 139 located in the third linear accelerator 22c are configured such that lateral converging lenses and longitudinal converging lenses alternate along the beamline BL. For example, the 14th, 16th and 18th level electrostatic quadrupole lens devices 134, 136 and 138 are lateral converging lenses, and the 15th, 17th and 19th level electrostatic quadrupole lens devices 135, 137 and 139 are longitudinal converging lenses.

[0062] Furthermore, the number of stages of the high-frequency accelerating section and the electrostatic quadrupole lens device included in the linear accelerating devices 22a to 22c is not limited to those shown in the illustrations, and can be configured with a different number of stages than those shown in the illustrations. Moreover, the configuration of the electrostatic quadrupole lens device can differ from the example shown in the illustrations. For example, at least one stage of the electrostatic quadrupole lens device may have a pair of lateral converging lenses and longitudinal converging lenses, or it may have multiple pairs of lateral converging lenses and longitudinal converging lenses.

[0063] Figure 3 (a) Figure 3 (b) is a front view showing the schematic structure of the electrostatic quadrupole lens devices 52a and 52b as viewed from the upstream side of the beamline. Figure 3 (a) The electrostatic quadrupole lens device 52a is a transverse focusing lens that focuses the ion beam IB in the transverse (x direction). Figure 3(b) The electrostatic quadrupole lens device 52b is a longitudinal converging lens that converges the ion beam IB in the longitudinal direction (y direction).

[0064] Figure 3 The electrostatic quadrupole lens device 52a (a) has a set of upper and lower lens electrodes 54a opposed in the longitudinal direction (y direction) and a set of left and right lens electrodes 56a opposed in the transverse direction (x direction). A negative potential -Qa is applied to the upper and lower lens electrodes 54a, and a positive potential +Qa is applied to the left and right lens electrodes 56a. The electrostatic quadrupole lens device 52a generates an attractive force with the negatively potentialed upper and lower lens electrodes 54a and a repulsive force with the positively potentialed left and right lens electrodes 56a relative to the ion beam IB composed of positively charged ion particles. Thus, the electrostatic quadrupole lens device 52a adjusts the beam shape to converge the ion beam IB in the x direction and diverge it in the y direction.

[0065] Figure 3 (b) the electrostatic quadrupole lens device 52b and Figure 3 (a) Similarly, it has a set of upper and lower lens electrodes 54b opposed in the longitudinal (y-direction) and a set of left and right lens electrodes 56b opposed in the transverse (x-direction). Figure 3 In (b), the sign of the applied potential and Figure 3 (a) Conversely, a positive potential +Qb is applied to the upper and lower lens electrodes 54b, and a negative potential -Qb is applied to the left and right lens electrodes 56b. As a result, the electrostatic quadrupole lens device 52b adjusts the beam shape to converge the ion beam IB in the y direction and diverge it in the x direction.

[0066] Figure 4 This is a cross-sectional view showing the schematic structure of the high-frequency acceleration unit 70, and illustrating the structure of the high-frequency acceleration unit corresponding to the first stage included in each of the linear acceleration devices 22a-22c. The high-frequency acceleration unit 70 includes a high-frequency electrode 72, a high-frequency resonator 74, a rod 76, and a high-frequency power supply 78. The high-frequency electrode 72 is a hollow cylindrical electrode body, through which the ion beam IB passes. The high-frequency electrode 72 is connected to the high-frequency resonator 74 via the rod 76. The high-frequency power supply 78 supplies a high-frequency voltage V to the high-frequency resonator 74. RF The central control unit 50 adjusts the high-frequency voltage V applied to the high-frequency electrode 72 by controlling the high-frequency resonator 74 and the high-frequency power supply 78. RF The voltage amplitude V0, frequency f, and phase φ.

[0067] Electrostatic quadrupole lens devices 52a and 52b are provided on the upstream and downstream sides of the high-frequency accelerating section 70. The electrostatic quadrupole lens device 52a on the upstream side has a first ground electrode 60a, a second ground electrode 62a, upper and lower lens electrodes 54a, left and right lens electrodes 56a, and a lens power supply 58a (for reference). Figure 3The upper and lower lens electrodes 54a and the left and right lens electrodes 56a are disposed between the first ground electrode 60a and the second ground electrode 62a. The downstream electrostatic quadrupole lens device 52b includes the first ground electrode 60b, the second ground electrode 62b, the upper and lower lens electrodes 54b, the left and right lens electrodes 56b, and the lens power supply 58b (see reference). Figure 3 The upper and lower lens electrodes 54b and the left and right lens electrodes 56b are disposed between the first ground electrode 60b and the second ground electrode 62b.

[0068] exist Figure 4 In the example, the upstream electrostatic quadrupole lens device 52a is a lateral converging (longitudinal diverging) lens, and the downstream electrostatic quadrupole lens device 52b is a longitudinal converging (lateral diverging) lens. Alternatively, depending on which stage the high-frequency accelerating unit 70 is in, the upstream electrostatic quadrupole lens device 52a can be a longitudinal converging (lateral diverging) lens, and the downstream electrostatic quadrupole lens device 52b a lateral converging (longitudinal diverging) lens. Lateral and longitudinal convergence can be changed by reversing the positive and negative values ​​of the voltages applied by the lens power supplies 58a and 58b.

[0069] Figure 4 The high-frequency acceleration section 70 utilizes the potential difference on the upstream gap 64 between the high-frequency electrode 72 and the upstream second ground electrode 62a, and the downstream gap 66 between the high-frequency electrode 72 and the downstream first ground electrode 60b, to accelerate or decelerate the ion particles 68 constituting the ion beam IB. For example, by adjusting the high-frequency voltage V... RF The phase φ is adjusted so that a negative voltage is applied to the high-frequency electrode 72 when the ion particle 68 passes through the upstream gap 64, and a positive voltage is applied to the high-frequency electrode 72 when the ion particle 68 passes through the downstream gap 66, thereby accelerating the ion particle 68 passing through the high-frequency acceleration section 70. In addition, the interior of the high-frequency electrode 72 is substantially at the same potential, so the ion particle 68 does not substantially accelerate or decelerate when passing through the interior of the high-frequency electrode 72.

[0070] Figure 5 A cross-sectional view showing the structure of the linear acceleration device in detail. Figure 5 To indicate Figure 2 (a) shows the structure upstream of the beam of the first linear acceleration device 22a, and also shows the first to fifth stage electrostatic quadrupole lens devices 121 to 125 and the first to third stage high-frequency acceleration units 101 to 103.

[0071] The first linear acceleration device 22a includes a vacuum chamber 140. The vacuum chamber 140 extends in the z-direction along the beam BL. The cross-section of the vacuum chamber 140 orthogonal to the beam BL is rectangular and has four partition walls extending in the z-direction. The vacuum chamber 140 has an upper wall 140a, a left side wall 140b, and a right side wall 140c as the four partition walls (see below). Figure 6 ) and the lower wall 140d.

[0072] Figure 6 This is a cross-sectional view showing the configuration of the vacuum chamber 140, and it shows a section orthogonal to the z-axis. Figure 5 Equivalent to along Figure 6 AA section. For example... Figure 6 As shown, the vacuum chamber 140 is configured with its orientation rotated 45 degrees around the z-axis. When viewed from the beamline BL, the upper wall 140a is not positioned vertically upwards (in the +y direction), but rather in the upper left (in the +v direction). The +v direction corresponds to the orientation of the vector synthesized from the unit vectors of the +x and +y directions. The left wall 140b, when viewed from the beamline BL, is positioned in the lower left (in the +u direction). The +u direction corresponds to the orientation of the vector synthesized from the unit vectors of the +x and -y directions. The right wall 140c, when viewed from the beamline BL, is positioned in the upper right (in the -u direction). The lower wall 140d, when viewed from the beamline BL, is positioned in the lower right (in the -v direction).

[0073] Figure 6 The arrangement of the high-frequency resonators 74a to 74c in each of the high-frequency acceleration units 101 to 103 is also shown. The first high-frequency resonator 74a in the first-stage high-frequency acceleration unit 101 is provided on the outer side of the upper wall 140a and is positioned in the +v direction when viewed from the beam ray BL. The first high-frequency resonator 74a is connected to the first high-frequency electrode 72a via a first rod 76a extending in the +v direction when viewed from the beam ray BL.

[0074] The second high-frequency resonator 74b of the second-stage high-frequency acceleration unit 102 is disposed on the outer side of the left side wall 140b and positioned in the +u direction when viewed from the beam ray BL. When viewed from the beam ray BL, the second high-frequency resonator 74b connects with the second high-frequency electrode 72b (see reference) via a second rod 76b extending in the +u direction. Figure 5 )connect.

[0075] The third high-frequency resonator 74c of the third-stage high-frequency acceleration unit 103 is disposed on the outer side of the right side wall 140c and positioned in the -u direction when viewed from the beam ray BL. When viewed from the beam ray BL, the third high-frequency resonator 74c connects with the third high-frequency electrode 72c (see reference) via a third rod 76c extending in the -u direction. Figure 5 )connect.

[0076] Furthermore, no high-frequency resonator is installed on the outer side of the lower wall 140d. A vacuum exhaust device 148 for evacuating the interior of the vacuum chamber 140 is provided on the lower wall 140d. The vacuum exhaust device 148 is positioned in the -v direction when viewed from the beam ray BL.

[0077] like Figure 6 As shown, by rotating the vacuum tank 140 45 degrees from the horizontal, the range of the high-frequency resonators 74a to 74c in the x and y directions can be reduced, thereby enabling the overall size of the first linear acceleration device 22a to be miniaturized.

[0078] In this specification, the direction in which the beamline BL extends is sometimes referred to as the axial direction. Furthermore, the direction orthogonal to the axial direction is sometimes referred to as the radial direction, and the direction orthogonal to both the axial and radial directions is sometimes referred to as the circumferential direction. The x-axis, y-axis, u-axis, and v-axis are each axes extending radially at different angles in the circumferential direction.

[0079] Return to Figure 5 The structure of the high-frequency acceleration units 101 to 103 will be described below. The first-stage high-frequency acceleration unit 101 includes a first high-frequency electrode 72a, a first high-frequency resonator 74a, a first rod 76a, and a first insulator 77a. The first rod 76a is inserted through a mounting hole 146 provided in the upper wall 140a. The first insulator 77a is provided outside the vacuum chamber 140 and inside the high-frequency resonator 74a. The first insulator 77a is mounted on the upper wall 140a and supports the first rod 76a. The first insulator 77a is cone-shaped and is configured to block the mounting hole 146. The first insulator 77a connects the vacuum chamber 140, which is at ground potential, with the applied high-frequency voltage V. RF Electrical insulation is provided between the first rod 76a and the first insulator 77a. The first insulator 77a is positioned in the +v direction when viewed from the beamline BL.

[0080] The second-stage high-frequency acceleration unit 102 includes a second high-frequency electrode 72b, a second high-frequency resonator 74b, a second rod 76b, and a second insulator (not shown). The second-stage high-frequency acceleration unit 102 is constructed identically to the first-stage high-frequency acceleration unit 101, but... Figure 6 As shown, the installation configurations differ. Specifically, the second rod 76b is positioned in the +u direction when viewed from the beamline BL. The second insulator is mounted on the left side wall 140b and supports the second rod 76b. The second insulator is positioned in the +u direction when viewed from the beamline BL.

[0081] The third-stage high-frequency acceleration unit 103 includes a third high-frequency electrode 72c, a third high-frequency resonator 74c, a third rod 76c, and a third insulator (not shown). The third-stage high-frequency acceleration unit 103 is constructed identically to the first-stage high-frequency acceleration unit 101, but... Figure 6 As shown, the installation configurations differ. Specifically, the third rod 76c is positioned in the -u direction when viewed from the beamline BL. The third insulator is mounted on the right side wall 140c and supports the third rod 76c. The third insulator is positioned in the -u direction when viewed from the beamline BL.

[0082] Multiple electrostatic quadrupole lens devices 121-125 are arranged inside the vacuum chamber 140. Each of the multiple electrostatic quadrupole lens devices 121-125 is configured as a lens unit 80. The lens unit 80 will... Figure 3 (a) Figure 3 (b) and Figure 4 The electrostatic quadrupole lens device 52a (or 52b) shown is a unitized assembly, in which the upper and lower lens electrodes 54a (or 54b), the left and right lens electrodes 56a (or 56b), the first ground electrode 60a (or 60b), and the second ground electrode 62a (or 62b) are integrated. In this specification, the lens unit 80 is also referred to as the electrostatic quadrupole lens device.

[0083] The lens unit 80 includes multiple lens electrodes 82, an upstream cover electrode 84a, a downstream cover electrode 84b, a base plate 86, and a mounting part 88.

[0084] Multiple lens electrodes 82 are equivalent to Figure 3 (a), Figure 3 (b) shows the upper and lower lens electrodes 54a (or 54b) and the left and right lens electrodes 56a (or 56b). Multiple lens electrodes 82 are radially opposed across the beamline BL and spaced apart circumferentially. Specifically, one set of upper and lower lens electrodes is opposed in the y-direction, and one set of left and right lens electrodes is opposed in the x-direction. Furthermore, the two upper and lower lens electrodes and the two left and right lens electrodes are alternately arranged circumferentially. Positive or negative converging / diverging voltages are applied to the multiple lens electrodes 82.

[0085] An upstream-side covering electrode 84a covers the upstream side of the beam line of the plurality of lens electrodes 82. The upstream-side covering electrode 84a is formed in a bowl shape, consisting only of curved surfaces or a combination of curved and flat surfaces, and has a beam entrance port at its center for the ion beam IB to pass through. The upstream-side covering electrode 84a is disposed axially or radially away from the plurality of lens electrodes 82. The upstream-side covering electrode 84a is a ground electrode, which is equivalent to... Figure 4 The first grounding electrode 60a (or 60b).

[0086] The downstream-side covering electrode 84b covers the downstream side of the beamline of the multiple lens electrodes 82. The downstream-side covering electrode 84b, like the upstream-side covering electrode 84a, is formed in a bowl shape consisting only of curved surfaces or a combination of curved and flat surfaces, and has a beam exit port at its center for the ion beam IB to pass through. The downstream-side covering electrode 84b is positioned axially or radially away from the multiple lens electrodes 82. The downstream-side covering electrode 84b is a ground electrode, which is equivalent to... Figure 4 The second grounding electrode 62a (or 62b).

[0087] A base plate 86 supports multiple lens electrodes 82, an upstream cover electrode 84a, and a downstream cover electrode 84b. The base plate 86 is a plate-shaped component with axial thickness. The multiple lens electrodes 82 are housed in a central opening penetrating the center of the base plate 86. The upstream cover electrode 84a is mounted on the upstream side of the base plate 86. The downstream cover electrode 84b is mounted on the downstream side of the base plate 86.

[0088] The mounting part 88 is a portion that is fixed to the vacuum chamber 140. The mounting part 88 is provided at the lower part of the base plate 86 and extends axially from the base plate 86. An axially extending mounting rod 142 is provided on the inner surface of the vacuum chamber 140. The mounting part 88 is fixed to the mounting rod 142 by fastening components 144 such as threads or bolts.

[0089] Figure 7 A perspective view showing an example of the appearance of lens unit 80 as viewed from the upstream side. Figure 7 The lens unit 80 is, for example, a second-stage electrostatic quadrupole lens device 122 adjacent to the upstream side of the first-stage high-frequency accelerating unit 101. The upstream-side cover electrode 84a has a beam inlet 92a through which the ion beam IB passes and multiple gas outlets (also called upstream-side gas outlets) 94a, 95a, and 96a. The beam inlet 92a is located at the center of the upstream-side cover electrode 84a and is axially open. The multiple upstream-side gas outlets 94a to 96a are located on the outer periphery of the upstream-side cover electrode 84a and are radially open. Each of the multiple upstream-side gas outlets 94a to 96a is provided for discharging gas from the interior of the lens unit 80 to the exterior.

[0090] Multiple upstream gas outlets 94a to 96a are each located at different positions circumferentially, for example, staggered by 90 degrees circumferentially. For instance, the first gas outlet 94a is located in the +u direction when viewed from the beam ray BL, the second gas outlet 95a is located in the -u direction, and the third gas outlet 96a is located in the -v direction. In the illustrated example, there is no gas outlet in the +v direction when viewed from the beam ray BL, but a fourth gas outlet may also be located in the +v direction when viewed from the beam ray BL.

[0091] Each of the multiple upstream gas outlets 94a to 96a is formed as a slit extending in the circumferential direction. Each of the multiple upstream gas outlets 94a to 96a is formed, for example, as a slit extending continuously over an angle range of approximately 10 to 60 degrees. Furthermore, each of the multiple upstream gas outlets 94a to 96a may not be continuously formed in the circumferential direction, or it may be formed intermittently in the circumferential direction. Each of the multiple upstream gas outlets 94a to 96a may be formed, for example, as a mesh, or as an array of tiny openings.

[0092] Mounting portions 88 are located at both ends of the base plate 86 in the left-right direction (u direction), and are not located near the center of the base plate 86 in the left-right direction. The mounting portions 88 are formed with a notch 88a on the upstream side. The upstream notch 88a is located between the beam BL and the vacuum exhaust device 148. The upstream notch 88a allows gas flowing from multiple upstream gas exhaust ports 94a to 96a toward the vacuum exhaust device 148 to pass through. The upstream notch 88a may also be discontinuous, forming a mesh or an array of tiny openings.

[0093] Figure 8 To indicate the view from the downstream side Figure 7 The diagram shows a perspective view of the lens unit 80. In the illustrated example, the upstream and downstream sides of the lens unit 80 have the same structure. The downstream cover electrode 84b has a beam exit port 92b through which the ion beam IB passes and multiple gas outlets (also referred to as downstream gas outlets) 94b, 95b, and 96b. The beam exit port 92b is located at the center of the downstream cover electrode 84b and is axially open. The multiple downstream gas outlets 94b to 96b are located on the outer periphery of the downstream cover electrode 84b and are radially open. The multiple downstream gas outlets 94b to 96b are configured, for example, the same as the multiple upstream gas outlets 94a to 96a provided on the upstream cover electrode 84a. Each of the multiple downstream gas outlets 94b to 96b is provided for discharging gas from the interior to the exterior of the lens unit 80.

[0094] The mounting section 88, like the upstream side, has a notch 88b located on the downstream side. The downstream notch 88b is positioned between the beam BL and the vacuum exhaust device 148. For example, the downstream notch 88b allows gas flowing from multiple downstream gas outlets 94b to 96b toward the vacuum exhaust device 148 to pass through. The downstream notch 88b may also be discontinuous, forming a mesh or an array of tiny openings.

[0095] Figure 9 To show in detail Figure 7 A cross-sectional view of the beamline BL of the internal structure of the lens unit 80, magnified. Figure 5 The diagram shows the lens unit 80. Figure 9 The lens unit 80 is, for example, a second-stage electrostatic quadrupole lens device 122 adjacent to the upstream side of the first-stage high-frequency accelerating unit 101. The lens unit 80 includes multiple insulating members 90 supporting each of the multiple lens electrodes 82. The multiple insulating members 90 are, for example, cylindrical insulators. Each of the multiple insulating members 90 extends radially outward from its corresponding lens electrode 82 toward the base plate 86. Each of the multiple insulating members 90 is mounted on the inner peripheral surface 86b of the central opening 86a of the base plate 86. A wiring port 86c extending in the v direction is provided at the lower part of the base plate 86. Wiring (not shown) for applying high voltage to the multiple lens electrodes 82 is inserted through the wiring port 86c.

[0096] The multiple gas outlets 94a-96a, 94b-96b, located on the upstream cover electrode 84a and the downstream cover electrode 84b, are positioned radially further away from the beam line BL than the multiple lens electrodes 82. That is, when viewed from the beam line BL, the multiple gas outlets 94a-96a, 94b-96b are located on the back side of the multiple lens electrodes 82. By providing multiple gas outlets 94a-96a, 94b-96b on the back side of the multiple lens electrodes 82, the spatial distribution of the converging / diverging electric field acting on the ion beam IB can be kept substantially unchanged. In other words, changes in the converging / diverging performance of the lens unit 80 based on the location of the gas outlets can be prevented.

[0097] The axial positions of the multiple gas outlets 94a-96a and 94b-96b are located within ranges C1 and C2 between the axial ends 82a and 82b of the multiple lens electrodes 82 and the axial positions of the multiple insulating members 90. The multiple upstream gas outlets 94a-96a are located within range C1 between the upstream ends 82a of the multiple lens electrodes 82 and the multiple insulating members 90. That is, the multiple upstream gas outlets 94a-96a are positioned to avoid being located further upstream than the upstream ends 82a of the multiple lens electrodes 82. This prevents changes in the performance of the grounding electrode, which is based on the upstream cover electrode 84a where the gas outlets are located. Furthermore, the multiple downstream gas outlets 94b-96b are located within range C2 between the downstream ends 82b of the multiple lens electrodes 82 and the multiple insulating members 90. That is, the multiple downstream gas outlets 94b-96b are positioned to avoid being located further downstream than the downstream ends 82b of the multiple lens electrodes 82. Therefore, it is possible to prevent changes in the function of the grounding electrode, which is based on the downstream cover electrode 84b with the gas outlet provided. Furthermore, by providing multiple gas outlets 94a to 96a and 94b to 96b at positions that avoid the axial direction of the multiple insulating components 90, the flow of gas toward the multiple insulating components 90 is suppressed, thereby suppressing sputtered particles from adhering to the multiple insulating components 90.

[0098] Figure 10 To show in detail Figure 7 A cross-sectional view of the beamline BL of the internal structure of the lens unit 80. Figure 10 Lens unit 80 for observing the state of the disassembled upstream side covering electrode 84a from the upstream side of the beam line. Figure 10 The lens unit 80 is, for example, a second-stage electrostatic quadrupole lens device 122 adjacent to the upstream side of the first-stage high-frequency acceleration unit 101.

[0099] Figure 10 To illustrate the circumferential arrangement of the plurality of lens electrodes 82 and the plurality of downstream gas outlets 94b to 96b, as shown in the figure, each of the plurality of downstream gas outlets 94b to 96b is circumferentially offset from the plurality of lens electrodes 82. For example, each of the plurality of downstream gas outlets 94b to 96b is offset from the plurality of lens electrodes 82 by 45 degrees. For example, when the direction in which the first rod 76a extends (+v direction) is taken as 0 degrees, the plurality of lens electrodes 82 are positioned at 45 degrees, 135 degrees, 225 degrees, and 315 degrees. The plurality of downstream gas outlets 94b to 96b are positioned at 270 degrees, 90 degrees, and 180 degrees. Furthermore, the plurality of upstream gas outlets 94a to 96a ( Figure 10 (Not shown in the figure) are also similarly configured at 270 degrees, 90 degrees, and 180 degrees to correspond to multiple downstream gas outlets 94b to 96b.

[0100] In the lens unit 80, the electrode bodies of the lens electrode 82 or the cover electrodes 84a and 84b are sputtered by the collision of the ion beam IB, causing the material constituting the sputtered electrode body to become sputtered particles. These sputtered particles may adhere as dirt to the surface of the electrode body or the insulating component 90. Since the sputtered particles are conductive, their adhesion to the electrode body surface creates fine irregularities, which can easily lead to discharges between the electrodes. For example, a discharge may occur between the lens electrode 82, which is subjected to a high voltage, and the cover electrodes 84a and 84b, which are at ground potential. Furthermore, if sputtered particles adhere to the surface of the insulating component 90, the insulation performance of the insulating component 90 may deteriorate, making it impossible to ensure electrical insulation between the lens electrode 82, which is subjected to a high voltage, and the base plate 86, which is at ground potential.

[0101] According to this embodiment, the lens unit 80 is provided with a plurality of gas outlets 94a-96a and 94b-96b, thus enabling the generation of gas flow from the interior of the lens unit 80 toward the exterior through the plurality of gas outlets 94a-96a and 94b-96b. For example, as Figure 10 As shown, a gas flow F is generated that flows towards the vacuum exhaust device 148 located at the lower part (-v direction) of the vacuum tank 140 through multiple downstream gas outlets 94b to 96b. At least a portion of the sputtered particles generated inside the lens unit 80 are discharged to the outside of the lens unit 80 by the gas flow F from the inside of the lens unit 80 to the outside. As a result, it is possible to suppress the adhesion of sputtered particles to the electrode body or insulating component 90 located inside the lens unit 80, thereby suppressing the generation of discharge between the electrode bodies and the degradation of the insulation performance of the insulating component 90.

[0102] exist Figure 10 In the lens unit 80 shown, no gas outlet is provided at the 0-degree position where the adjacent first rod 76a is located. The first rod 76a is supported by the first insulator 77a. If sputtered particles adhere to the first insulator 77a, the insulation performance of the first insulator 77a will decrease. By not providing a gas outlet at the 0-degree position where the adjacent first rod 76a is located, the splashing of sputtered particles toward the first insulator 77a can be suppressed, thereby suppressing the decrease in the insulation performance of the first insulator 77a.

[0103] To suppress the splashing of sputtered particles toward the first insulator 77a, it is preferable to provide multiple downstream gas outlets 94b to 96b at positions circumferentially offset by more than 45 degrees relative to the first rod 76a. In particular, it is preferable not to provide gas outlets in the +v direction when viewed from the beamline BL in the cover electrode adjacent to the first-stage high-frequency accelerating unit 101. The cover electrodes adjacent to the first-stage high-frequency accelerating unit 101 are the downstream cover electrode of the second-stage electrostatic quadrupole lens device 122 and the upstream cover electrode of the third-stage electrostatic quadrupole lens device 123.

[0104] Additionally, in the second-stage high-frequency acceleration unit 102, a second rod 76b exists at a position in the +u direction when viewed from the beamline BL (reference). Figure 6 Therefore, in the case of the cover electrode adjacent to the second-stage high-frequency accelerating unit 102, it is preferable that no gas outlet is provided in the +u direction when viewed from the beam ray BL, and multiple gas outlets are provided in the +v, -v, and -u directions. The cover electrode adjacent to the second-stage high-frequency accelerating unit 102 is the downstream cover electrode of the third-stage electrostatic quadrupole lens device 123 and the upstream cover electrode of the fourth-stage electrostatic quadrupole lens device 124.

[0105] Furthermore, in the third-stage high-frequency acceleration unit 103, a third rod 76c exists at a position in the -u direction when viewed from the beamline BL (reference). Figure 6 Therefore, in the case of the cover electrode adjacent to the third-stage high-frequency accelerating unit 103, it is preferable that no gas outlet is provided in the -u direction when viewed from the beam ray BL, and multiple gas outlets are provided in the +v, -v, and +u directions. The cover electrode adjacent to the third-stage high-frequency accelerating unit 103 is the downstream cover electrode of the fourth-stage electrostatic quadrupole lens device 124 and the upstream cover electrode of the fifth-stage electrostatic quadrupole lens device 125.

[0106] Furthermore, in the case where the cover electrode is not adjacent to the high-frequency accelerating unit, gas outlets can be provided in four directions: ±v and ±u. That is, the cover electrode can have four gas outlets located at 0 degrees, 90 degrees, 180 degrees, and 270 degrees. The cover electrodes not adjacent to the high-frequency accelerating unit are the upstream and downstream cover electrodes of the first-stage electrostatic quadrupole lens device 121, and the upstream cover electrode of the second-stage electrostatic quadrupole lens device 122.

[0107] According to this embodiment, by providing notches 88a and 88b in the mounting portion 88, the conductivity of the gas flowing toward the vacuum exhaust device 148 can be improved. In particular, by providing notches 88a and 88b in the portion where multiple lens units 80 are continuously provided, residual gas can be effectively discharged. For example, residual gas can be effectively discharged from the space between consecutively adjacent first-stage and second-stage electrostatic quadrupole lens devices 121 and 122.

[0108] According to this embodiment, residual gas can be effectively discharged from the interior of the lens unit 80 through multiple gas outlets 94a-96a and 94b-96b, thereby increasing the vacuum level inside the lens unit 80. Furthermore, residual gas can be effectively discharged from the space surrounding the lens unit 80 through notches 88a and 88b, further increasing the vacuum level. This improves the overall vacuum level of the vacuum chamber 140 along the beamline BL. Consequently, the effects of valence reduction or ion neutralization of ions constituting the ion beam IB due to interaction between the ion beam IB and residual gas are mitigated. This improves the delivery efficiency of the ion beam IB based on the beam acceleration unit 14, thereby suppressing the decrease in beam current of the ion beam IB output from the beam acceleration unit 14.

[0109] This embodiment can be applied to ultra-high energy multi-stage linear acceleration units that accelerate the ion beam IB to 4 MeV or higher. To accelerate the ion beam IB to 4 MeV or higher, it is necessary to further increase the accelerating voltage applied to each stage of the high-frequency accelerating section 101-115, and also to further increase the convergence / divergence voltage applied to each stage of the electrostatic quadrupole lens device 121-139. Applying a larger voltage makes it easier for discharge between the electrode bodies to occur. According to this embodiment, contamination of the electrode bodies or insulating components based on sputtered particles can be suppressed, thereby suppressing the generation of discharge between the electrode bodies.

[0110] This embodiment can be applied to high-energy multi-stage linear acceleration units that accelerate ion beams IB containing multivalent ions. In the high-frequency acceleration section, the acceleration energy of the ion beam IB and the acceleration voltage applied to the high-frequency acceleration section are proportional to the product of the ion's valence. Therefore, by using ions with high valence, the acceleration energy can be increased compared to using ions with low valence. On the other hand, ions with high valence (e.g., ions with valence of 3 or higher or 4 or higher) readily interact with the residual gas present in the beamline BL, and their valence decreases due to this interaction, resulting in loss during beam delivery. According to this embodiment, the vacuum level of the beamline BL can be increased, thus suppressing the loss of multivalent ions and thereby suppressing the decrease in the beam current of the ion beam IB output from the beam acceleration unit 14.

[0111] The lens unit 80 described in this embodiment can be applied to all of the multi-stage electrostatic quadrupole lens devices 121-139 provided in the beam acceleration unit 14. That is, a gas exhaust port can be provided on the cover electrode of each of the multi-stage electrostatic quadrupole lens devices 121-139. Furthermore, the lens unit 80 described in this embodiment can be applied to a portion of the multi-stage electrostatic quadrupole lens devices 121-139 provided in the beam acceleration unit 14. That is, the lens unit 80 can be applied to at least one stage of the multi-stage electrostatic quadrupole lens devices 121-139.

[0112] The lens unit 80 described in this embodiment can be applied to at least one stage of an electrostatic quadrupole lens device from the top stage to a predetermined number of stages in the beam acceleration unit 14. For example, the lens unit 80 can be applied to... Figure 5 The electrostatic quadrupole lens devices 121 to 125, from stage 1 to stage 5, are shown. Sputtered particles generated in lens unit 80 tend to be generated at relatively low ion beam IB energies, thus they tend to be generated upstream of the downstream portion of beam acceleration unit 14. For example, sputtered particles are more likely to be generated in the first linear acceleration unit 22a compared to the second linear acceleration unit 22b or the third linear acceleration unit 22c. Therefore, by applying lens unit 80 upstream of the beam acceleration unit 14, where sputtered particles are easily generated, it is easy to obtain an effect based on sputtered particle discharge. On the other hand, in electrostatic quadrupole lens devices (e.g., 126 to 139) downstream of the beam acceleration unit 14, where sputtered particles are less likely to be generated, a gas exhaust port may not be required on the cover electrode.

[0113] The present invention has been described above with reference to the various embodiments described above, but the present invention is not limited to the embodiments described above. Appropriate combinations or substitutions of the structures of the embodiments are also included in the present invention. Furthermore, based on the knowledge of those skilled in the art, it is possible to appropriately change the combination or processing order of the embodiments or to make various design changes or modifications to the embodiments, and the embodiments with such modifications are also included within the scope of the present invention.

[0114] In the above embodiments, it is shown that multiple gas outlets 94a-96a and 94b-96b are provided on both the upstream covering electrode 84a and the downstream covering electrode 84b. In another embodiment, multiple gas outlets may be provided on only one of the upstream covering electrode 84a and the downstream covering electrode 84b.

[0115] In the above embodiments, it is shown that each of the upstream-side covering electrode 84a and the downstream-side covering electrode 84b has multiple gas outlets 94a-96a and 94b-96b. In another embodiment, only one gas outlet may be provided on at least one of the upstream-side covering electrode 84a and the downstream-side covering electrode 84b. Therefore, at least one of the upstream-side covering electrode 84a and the downstream-side covering electrode 84b may have at least one gas outlet.

Claims

1. An ion implantation apparatus comprising a high-energy multi-stage linear acceleration unit for accelerating an ion beam, characterized in that the high-energy multi-stage linear acceleration unit comprises: a multi-stage high-frequency acceleration section disposed along the beamline of the ion beam; and a multi-stage electrostatic quadrupole lens device disposed along the beamline. Electrostatic quadrupole lens devices at various levels include: Multiple lens electrodes are spaced apart from the beamline, are opposed in a radial direction orthogonal to the axis extending from the beamline, and are spaced apart in a circumferential direction orthogonal to both the axial and radial directions. An upstream side covering electrode covers the upstream side of the beamline of the plurality of lens electrodes and has a beam inlet with an opening in the axial direction; and The downstream side covering electrode covers the downstream side of the beamline of the plurality of lens electrodes and has a beam exit port with an opening in the axial direction. At least one of the upstream and downstream cover electrodes included in the multi-stage electrostatic quadrupole lens device has at least one gas outlet in the radial opening.

2. The ion implantation apparatus according to claim 1, characterized in that, The at least one gas outlet is located radially further away from the beamline than the plurality of lens electrodes.

3. The ion implantation apparatus according to claim 1 or 2, characterized in that, The at least one gas outlet is located at a position offset from each of the plurality of lens electrodes in the circumferential direction.

4. The ion implantation apparatus according to claim 3, characterized in that, The at least one gas outlet is located at a position offset by 45 degrees in the circumferential direction relative to at least one of the plurality of lens electrodes.

5. The ion implantation apparatus according to claim 1, characterized in that, The at least one gas outlet includes a plurality of gas outlets located at different positions in the circumferential direction.

6. The ion implantation apparatus according to claim 1, characterized in that, The at least one gas outlet is formed as a slit extending in the circumferential direction.

7. The ion implantation apparatus according to claim 1, characterized in that, The at least one gas outlet is formed as a mesh or an array of tiny openings.

8. The ion implantation apparatus according to claim 1, characterized in that, The electrostatic quadrupole lens device at each stage further includes multiple insulating components supporting each of the multiple lens electrodes, and each of the multiple insulating components is arranged to extend radially outward from its corresponding lens electrode. The axial position of the at least one gas outlet is between the axial end positions of the plurality of lens electrodes and the axial positions of the plurality of insulating components.

9. The ion implantation apparatus according to claim 1, characterized in that, The various high-frequency acceleration units include: a hollow cylindrical high-frequency electrode through which the ion beam passes; a rod extending radially outward from the high-frequency electrode; a high-frequency resonator connected to the high-frequency electrode via the rod; and an insulator supporting the rod. The at least one gas outlet is disposed at a position offset relative to the rod in the circumferential direction, the rod extending from a high-frequency electrode adjacent to the covering electrode in the axial direction.

10. The ion implantation apparatus according to claim 9, characterized in that, The at least one gas outlet is located at a position offset by more than 45 degrees from the rod in the circumferential direction.

11. The ion implantation apparatus according to claim 9, characterized in that, The at least one gas outlet includes: a first gas outlet disposed at a position offset from the rod by 90 degrees in the circumferential direction; a second gas outlet disposed at a position offset from the rod by 180 degrees in the circumferential direction; and a third gas outlet disposed at a position offset from the rod by 270 degrees in the circumferential direction.

12. The ion implantation apparatus according to claim 1, characterized in that, The electrostatic quadrupole lens device further includes: a base plate supporting the plurality of lens electrodes and the cover electrode; and a mounting portion extending from the base plate along the axial direction and fixed to the vacuum chamber of the high-energy multi-stage linear acceleration unit. The mounting portion included in the at least one electrostatic quadrupole lens device in the multi-stage configuration has a notch for allowing gas to pass through the vacuum chamber.

13. The ion implantation apparatus according to claim 12, characterized in that, The notch is located between the beam line and the vacuum exhaust device connected to the vacuum chamber.

14. The ion implantation apparatus according to claim 12, characterized in that, The gaps are formed as mesh or an array of tiny openings.

15. The ion implantation apparatus according to claim 12, characterized in that, The electrostatic quadrupole lens device with the notch is arranged adjacent to other electrostatic quadrupole lens devices along the axial direction.

16. The ion implantation apparatus according to claim 1, characterized in that, The at least one electrostatic quadrupole lens device in the multi-stage is disposed in at least one of the stages from the top of the high-energy multi-stage linear acceleration unit to a specified number of stages.

17. The ion implantation apparatus according to claim 1, characterized in that, The high-energy multi-stage linear acceleration unit accelerates the ion beam containing multivalent ions.

18. The ion implantation apparatus according to claim 1, characterized in that, The high-energy multi-stage linear acceleration unit accelerates the ion beam to energies above 4 MeV.

19. The ion implantation apparatus according to claim 1, characterized in that, The multi-stage high-frequency acceleration section has 10 or more stages, and the multi-stage electrostatic quadrupole lens device has 10 or more stages.

20. An electrostatic quadrupole lens device, characterized in that, have: Multiple lens electrodes are spaced apart by a beamline, are opposed to each other in a radial direction orthogonal to the axis extending from the beamline, and are spaced apart in a circumferential direction orthogonal to both the axial and radial directions. An upstream side covering electrode covers the upstream side of the beamline of the plurality of lens electrodes and has a beam inlet with an opening in the axial direction; and The downstream side covering electrode covers the downstream side of the beamline of the plurality of lens electrodes and has a beam exit port with an opening in the axial direction. At least one of the upstream and downstream cover electrodes has at least one gas outlet in the radial opening.

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