Fast Faraday cup detector for radio frequency ion implanter

Abstract

The invention discloses a fast Faraday cup detector for a radio frequency ion implanter, which comprises a fast Faraday cup arranged in the ion implanter and an external driving assembly, and is characterized in that the fast Faraday cup is in transmission connection with the driving assembly; the fast Faraday cup comprises a shell, and a front baffle plate, an insulating plate and a microstrip line assembly which are arranged in the shell, beam holes are formed in the centers of the front baffle plate and the insulating plate, and a microstrip line cavity is formed between the insulating plate and the microstrip line assembly; when the fast Faraday cup is used for measuring the longitudinal distribution of the micro-beam bunches, the driving assembly drives the fast Faraday cup to be inserted into the beam track center of the ion implanter, so that the beam hole in the fast Faraday cup moves to be concentric with the beam light path center, and the beam center part is intercepted to enter the microstrip line cavity; and bombardment is carried out on the microstrip line assembly for measurement. According to the invention, the microstrip line structure is used as a beam receiver, has a high frequency band width, can quickly respond to a beam signal, and can accurately monitor the longitudinal distribution of beams in a microbeam bunch.

Description

Fast Faraday Cup Detector for Radio Frequency Ion Implanters Technical Field

[0001] This invention relates to the field of beam diagnostics for ion implanters, and more specifically to a fast Faraday cup detector for radio frequency ion implanters. Background Technology

[0002] Unlike electrostatic ion implanters, radio frequency (RF) ion implanters use a radio frequency electric field to longitudinally accelerate the ion beam. This causes the beam to propagate as individual micro-clusters during the RF acceleration phase. Knowing the longitudinal current distribution of these individual beam micro-clusters is crucial for prototype verification and initial beam tuning of RF ion implanters.

[0003] Commonly used ion implanter current detection systems employ Faraday cup detectors. The basic principle is that when an ion beam bombards a collector electrode that is electrically insulated from the surrounding tubing, the positively charged ion beam requires external electron migration to maintain charge balance on the collector electrode, thus forming a current that can be detected. However, the Faraday cup responds slowly to current changes, and the output current amplitude is a stable average value, making it impossible to measure and reflect the longitudinal distribution of the beam current within a single micro-bundle. By reading the real-time beam current status through a beam current monitoring system, users can obtain beam current parameter adjustment references, providing direction for troubleshooting and device optimization. For radio frequency ion implanters, monitoring the longitudinal distribution of the micro-bundle provides users with information on the longitudinal beam focusing status, offering adjustment references for the longitudinal beam focusr and determining whether its structure meets kinetic design requirements. Summary of the Invention

[0004] The technical problem to be solved by this invention is that existing ion implanters generally use Faraday cups for current measurement, which can only provide the average current intensity of the beam in actual operation and cannot provide information on the longitudinal distribution within the beam cluster. The invention provides a fast Faraday cup detector for radio frequency ion implanters that is compact, easy to operate, and capable of accurately monitoring the longitudinal distribution of micro-beam clusters.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a fast Faraday cup detector for a radio frequency ion implanter, comprising a fast Faraday cup disposed inside the ion implanter and a driving assembly disposed outside the ion implanter, wherein the fast Faraday cup and the driving assembly are connected by a connecting rod; the fast Faraday cup comprises a shell and a front baffle, an insulating plate and a microstrip line assembly disposed sequentially inside the shell, wherein the front baffle and the insulating plate are provided with a beam aperture at their center, and a microstrip line chamber is provided between the insulating plate and the microstrip line assembly; when the fast Faraday cup is used to measure the longitudinal distribution of the micro-beam cluster, the driving assembly drives the connecting rod to insert the fast Faraday cup into the center of the beam track of the ion implanter, so that the beam aperture on the fast Faraday cup moves to be concentric with the center of the beam optical path, so as to intercept the central part of the beam to enter the microstrip line chamber and bombard the microstrip line assembly for measurement.

[0006] As a further improvement of the present invention, the microstrip line assembly includes a grounding metal plate, a surface conductor, and a dielectric substrate; the grounding metal plate is disposed on the back side of the dielectric substrate, the surface conductor is disposed laterally on the front side of the dielectric substrate, and the surface conductor corresponds to the beam aperture; when the center portion of the beam enters the microstrip line chamber through the beam aperture, it drifts in the chamber and bombards the surface conductor to perform beam intensity measurement.

[0007] As a further improvement of the present invention, an SMA coaxial connector is welded to each end of the surface conductor. One of the SMA coaxial connectors is connected to the load for signal absorption, and the other SMA coaxial connector serves as a measurement end and is provided with a signal output port for radio frequency signal output.

[0008] As a further improvement of the present invention, the SMA coaxial connector includes an inner conductor and an outer conductor, wherein the inner conductor is welded to the surface conductor and the outer conductor is connected to a grounded metal plate.

[0009] As a further improvement of the present invention, a water-cooled plate is provided on the back of the grounding metal plate, and a cooling channel is provided inside the water-cooled plate.

[0010] As a further improvement of the present invention, the grounding metal plate and the surface conductor are both made of copper; the dielectric substrate is made of ceramic; and the outer shell is made of aluminum.

[0011] As a further improvement of the present invention, the diameter of the beam aperture is 1 to 2 mm.

[0012] As a further improvement of the present invention, the driving assembly includes a driving motor, a connecting flange, a bellows, and a connecting plate; the connecting flange is sealed to the radio frequency acceleration unit of the radio frequency ion implanter, a mounting plate is provided on one side of the top of the connecting flange, the driving motor is fixed on the mounting plate, one end of the connecting plate is connected to the output end of the driving motor, a bellows is provided between the other end of the connecting plate and the top of the connecting flange, one end of the connecting rod is connected to the side of the outer shell, and the other end of the connecting rod is sealed through the connecting flange and the bellows and then connected to the connecting plate; under the drive of the driving motor, the connecting plate drives the connecting rod to rise and fall, so as to realize the insertion or extraction of the fast Faraday cup into or out of the beam track center of the ion implanter.

[0013] As a further improvement of the present invention, the drive assembly further includes a support frame and a sliding assembly. The support frame is disposed on one side of the connecting flange, and the sliding assembly is slidably disposed on the support frame in a vertical direction. The sliding assembly is connected to the connecting plate to assist in the lifting and lowering of the fast Faraday cup.

[0014] As a further improvement of the present invention, the connecting flange is also provided with a coaxial feedthrough, which is connected to the microstrip line assembly to realize the signal output of the microstrip line assembly.

[0015] Compared with existing technologies, the advantages of this invention are as follows: The fast Faraday cup detector for radio frequency ion implanters of this invention utilizes the microstrip line components in the fast Faraday cup as beam receivers, possessing a high bandwidth and enabling rapid response to beam signals, thus monitoring the longitudinal distribution of the beam within the micro-cluster. Furthermore, by placing the fast Faraday cup at different positions in the radio frequency acceleration section of the ion implanter, the beam's micro-cluster focusing and drift acceleration states throughout the acceleration process can be effectively characterized, providing data support for the design of the instrument's beam focuser and the overall optical path design. Attached Figure Description

[0016] Figure 1 is a schematic diagram of the cross-sectional side view of the fast Faraday cup detector in a specific embodiment of the present invention; Figure 2 is a schematic diagram of the front view of the fast Faraday cup detector in a specific embodiment of the present invention; Figure 3 is a schematic diagram of the front view of the microstrip line in a specific embodiment of the present invention; Figure 4 is a schematic diagram of the structure of the external motion control mechanism in a specific embodiment of the present invention.

[0017] Legend: 1. Front baffle; 2. Insulating plate; 3. Beam aperture; 4. Microstrip line chamber; 5. Microstrip line assembly; 6. Cooling channel; 7. Grounding metal plate; 8. Surface conductor; 9. Dielectric substrate; 10. Water-cooled plate; 11. Connecting rod; 12. Fastening screw; 13. Mounting hole; 14. SMA coaxial connector; 15. Signal output port; 16. Load; 17. Support frame; 18. Sliding assembly; 19. Drive motor; 20. Connecting flange; 21. Coaxial feedthrough; 22. Bellows; 23. Connecting plate; 24. Mounting plate; 100. Housing. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention.

[0019] In the description of this invention, it should be understood that the terms "side", "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0020] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more unless otherwise explicitly specified.

[0021] As shown in Figures 1 and 2, the fast Faraday cup detector for a radio frequency ion implanter of the present invention includes a fast Faraday cup disposed inside the ion implanter and a driving assembly disposed outside the ion implanter. The fast Faraday cup and the driving assembly are connected by a connecting rod 11. Since the fast Faraday cup is an intercepting probe, it will obstruct the beam advance during use. Therefore, an external driving assembly is required to control whether it is inserted into the beam track of the ion implanter for detection. During use, it is inserted to measure the longitudinal distribution of the beam at that position. After the measurement is completed, it is pulled out, no longer obstructing the beam advance.

[0022] The fast Faraday cup includes a housing 100 and a front baffle 1, an insulating plate 2, and a microstrip line assembly 5 sequentially disposed within the housing 100. Fastening screws 12 are provided at the four vertices of the front baffle 1 and the insulating plate 2 for connection and fixation. A beam aperture 3 with a diameter of 1-2 mm is provided at the center of the front baffle 1 and the insulating plate 2. A microstrip line chamber 4 is provided between the insulating plate 2 and the microstrip line assembly 5, and a corresponding beam aperture 3 is also provided on the microstrip line chamber 4. When using the fast Faraday cup to measure the longitudinal distribution of the micro-beam cluster, the drive assembly drives the connecting rod 11 to insert the fast Faraday cup into the center of the beam track of the ion implanter, causing the beam aperture 3 on the fast Faraday cup to move concentrically with the center of the beam path. As the beam advances, it first bombards the front baffle 1, where most of the beam is blocked. Only the central portion of the beam enters the microstrip line chamber 4 and bombards the microstrip line assembly 5 for measurement. Using microstrip line components as the basic structure has the advantages of wide bandwidth and extremely low response time. Moreover, the microstrip line components 5, microstrip line chamber 4, front baffle 1 and other structures are all independent modules, which are simple to process, connected by screws, and easy to replace.

[0023] In this embodiment, the front baffle 1 can be made of graphite to reduce byproducts of ion bombardment. A ceramic plate is placed between the front baffle 1 and the microstrip chamber 4 as an insulating plate 2, and the front baffle 1 is grounded separately to reduce interference from beam bombardment on the detection signal.

[0024] As shown in Figures 1 and 3, the microstrip line assembly 5 includes a grounding metal plate 7, a surface conductor 8, and a dielectric substrate 9. Mounting holes 13 are provided at the four vertices of the dielectric substrate 9 for easy installation. The grounding metal plate 7 is disposed on the back side of the dielectric substrate 9, and the surface conductor 8 is laterally disposed at the center of the front side of the dielectric substrate 9, corresponding to the beam aperture 3. When the central portion of the beam enters the microstrip line chamber 4 through the beam aperture 3, it drifts a certain distance within the chamber before striking the surface conductor 8 for beam intensity measurement.

[0025] As shown in Figure 3, an SMA coaxial connector 14 is soldered to each end of the surface conductor 8. One SMA coaxial connector 14 is connected to the load 16 to absorb signals and reduce the influence of signal reflection on the measurement end when there is no load at that end. The other SMA coaxial connector 14 serves as the measurement end and is provided with a signal output port 15, which is connected to a coaxial cable to lead out the signal. Further, the SMA coaxial connector 14 includes an inner conductor and an outer conductor. The inner conductor is soldered to the surface conductor 8, and the outer conductor is connected to the grounding metal plate 7.

[0026] In this embodiment, the characteristic impedance of the microstrip line component 5 in the load 16 is designed to be 50Ω (the characteristic impedance is related to the width of the upper surface conductor, the relative permittivity of the dielectric substrate, the thickness of the dielectric substrate, etc.), the bandwidth can reach 16GHz, the response time is extremely low, and the beam intensity information bombarding the conductor surface 8 can be output in real time. The time resolution can reach the sub-ns level, which meets the requirements of radio frequency ion implanters with operating frequencies in the MHz range.

[0027] It should be noted that after the beam enters the microstrip line chamber 4, there will be a drift space (vacuum region). The length of this drift space cannot allow the beam to freely diffuse beyond the width of the microstrip line assembly 5, so as to prevent the beam from bombarding the exposed dielectric substrates 9 on both sides of the surface conductor 8, causing signal noise and arcing due to charge accumulation on the dielectric substrates 9. At the same time, the length of this drift space cannot be too short, causing the top cover of the microstrip line chamber 4 to be too close to the microstrip line assembly 5, resulting in capacitance between them and causing a change in the characteristic impedance of the microstrip line assembly 5. Therefore, it is necessary to set an appropriate size for the beam aperture 3 and the thickness of the front baffle 1 and the insulating plate 2 to give the beam entering the microstrip line chamber 4 a certain directionality. At the same time, a dielectric substrate 9 with a suitable dielectric constant and an appropriate substrate thickness are selected to control the microstrip line width to meet the requirements of the beam under test, and the characteristic impedance of the microstrip line is controlled to be 50Ω to match the impedance of the external signal receiving device.

[0028] As shown in Figure 1, a water-cooled plate 10 is provided on the back of the grounded metal plate 7, and a cooling channel 6 is provided inside the water-cooled plate 10 to reduce the thermal effect of the device caused by beam bombardment.

[0029] In this embodiment, the grounding metal plate 7 and the surface conductor 8 are both made of copper, a metal with high electrical conductivity. The dielectric substrate 9 is made of ceramic, which is resistant to high temperatures and has low dielectric loss. The outer casing 100 and the water-cooling plate 10 are made of aluminum, a metal with relatively low mass.

[0030] As shown in Figure 4, the drive assembly includes a support frame 17, a sliding assembly 18, a drive motor 19, a connecting flange 20, a bellows 22, and a connecting plate 23. The connecting flange 20 is sealed to the radio frequency acceleration unit of the radio frequency ion implanter. A mounting plate 24 is provided on one side of the top of the connecting flange 20, and the drive motor 19 is fixed on the mounting plate 24. One end of the connecting plate 23 is connected to the output end of the drive motor 19, and a bellows 22 is provided between the other end of the connecting plate 23 and the top of the connecting flange 20. One end of the connecting rod 11 is connected to the side of the housing 100, and the other end of the connecting rod 11 is sealed through the connecting flange 20 and the bellows 22 and then connected to the connecting plate 23. The support frame 17 is located on one side of the connecting flange 20. The slide rail in the sliding assembly 18 is slidably mounted on the support frame 17 in the vertical direction, and the slider in the sliding assembly 18 is connected to the connecting plate 23. Driven by the drive motor 19, the connecting plate 23 drives the connecting rod 11 and the slider to move up and down along the slide rail to achieve precise insertion or extraction of the fast Faraday cup into or out of the beam track center of the ion implanter.

[0031] As shown in Figure 4, a coaxial feedthrough 21 is also provided on the connecting flange 20 for internal and external connection of radio frequency signals, while ensuring the vacuum seal of the beam cavity. Specifically, the coaxial feedthrough 21 is connected to the signal output port 15 of the measurement end of the SMA coaxial connector 14 via a coaxial cable. After the signal is led out from the coaxial feedthrough 21, it is connected to electronic components such as a low-noise amplifier or directly to an oscilloscope for signal processing and analysis, so as to obtain the longitudinal distribution within the beam cluster in real time, provide beam parameter adjustment reference for ion implanter users, and provide direction for ion implanter troubleshooting and device optimization.

[0032] In this embodiment, when the fast Faraday cup detector is applied to the radio frequency ion implanter, the structure of the connecting flange 20 can be configured to be the same as that of the radio frequency acceleration unit, allowing it to be compatible with the existing acceleration unit holes of the machine to measure the longitudinal distribution of the beam at various positions in the radio frequency acceleration section. Especially at the first radio frequency acceleration unit position after the radio frequency focusing unit, the longitudinal distribution state within the beam micro-cluster at this position can directly characterize the focusing situation of the focusing unit and whether the focusing effect matches that of the radio frequency acceleration unit, which is of great significance for the research and development and prototype debugging of the radio frequency ion implanter.

[0033] It should be noted that the fast Faraday cup will block most of the beam during use, leaving only the central part of the beam for measurement. That is, it can only measure the longitudinal distribution of the beam, but cannot provide the absolute value of the beam intensity. It can be used in conjunction with the conventional Faraday cup to obtain more comprehensive beam information.

[0034] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A fast Faraday cup detector for a radio frequency ion implanter, characterized in that, The device includes a fast Faraday cup located inside an ion implanter and a drive assembly located outside the ion implanter. The fast Faraday cup and the drive assembly are connected by a connecting rod (11). The fast Faraday cup includes a housing (100) and a front baffle (1), an insulating plate (2), and a microstrip line assembly (5) sequentially located inside the housing (100). The front baffle (1) and the insulating plate (2) are provided with beam holes (3) at their centers. A microstrip line chamber (4) is provided between the insulating plate (2) and the microstrip line assembly (5). When the fast Faraday cup is used to measure the longitudinal distribution of the micro-beam cluster, the drive assembly drives the connecting rod (11) to insert the fast Faraday cup into the center of the beam track of the ion implanter, so that the beam hole (3) on the fast Faraday cup moves to be concentric with the center of the beam path, so as to intercept the central part of the beam and enter the microstrip line chamber (4) and bombard the microstrip line assembly (5) for measurement.

2. The fast Faraday cup detector for a radio frequency ion implanter according to claim 1, characterized in that, The microstrip line assembly (5) includes a ground metal plate (7), a surface conductor (8), and a dielectric substrate (9); the ground metal plate (7) is disposed on the back side of the dielectric substrate (9), and the surface conductor (8) is disposed laterally on the front side of the dielectric substrate (9), and the surface conductor (8) corresponds to the beam aperture (3); when the center part of the beam enters the microstrip line cavity (4) through the beam aperture (3), it drifts in the cavity and bombards the surface conductor (8) to perform beam intensity measurement.

3. The fast Faraday cup detector for a radio frequency ion implanter according to claim 2, characterized in that, An SMA coaxial connector (14) is soldered to each end of the surface conductor (8). One of the SMA coaxial connectors (14) is connected to the load (16) for signal absorption, and the other SMA coaxial connector (14) serves as the measurement end and is provided with a signal output port (15) for radio frequency signal output.

4. The fast Faraday cup detector for a radio frequency ion implanter according to claim 3, characterized in that, The SMA coaxial connector (14) includes an inner conductor and an outer conductor, the inner conductor being welded to a surface conductor (8), and the outer conductor being connected to a grounded metal plate (7).

5. The fast Faraday cup detector for a radio frequency ion implanter according to claim 2, characterized in that, The back of the grounding metal plate (7) is provided with a water-cooled plate (10), and the water-cooled plate (10) is provided with a cooling channel (6).

6. The fast Faraday cup detector for a radio frequency ion implanter according to any one of claims 2 to 5, characterized in that, The grounding metal plate (7) and the surface conductor (8) are both made of copper; the dielectric substrate (9) is made of ceramic; and the outer shell (100) is made of aluminum.

7. The fast Faraday cup detector for a radio frequency ion implanter according to any one of claims 1 to 5, characterized in that, The diameter of the beam aperture (3) is 1-2 mm.

8. The fast Faraday cup detector for a radio frequency ion implanter according to any one of claims 1 to 5, characterized in that, The drive assembly includes a drive motor (19), a connecting flange (20), a bellows (22), and a connecting plate (23). The connecting flange (20) is sealed to the radio frequency acceleration unit of the radio frequency ion implanter. A mounting plate (24) is provided on one side of the top of the connecting flange (20). The drive motor (19) is fixed on the mounting plate (24). One end of the connecting plate (23) is connected to the output end of the drive motor (19). A bellows (22) is provided between the other end of the connecting plate (23) and the top of the connecting flange (20). One end of the connecting rod (11) is connected to the side of the outer shell (100). The other end of the connecting rod (11) is sealed through the connecting flange (20) and the bellows (22) and then connected to the connecting plate (23). Under the drive of the drive motor (19), the connecting plate (23) drives the connecting rod (11) to rise and fall, so as to realize the insertion or extraction of the fast Faraday cup into or out of the beam track center of the ion implanter.

9. The fast Faraday cup detector for a radio frequency ion implanter according to claim 8, characterized in that, The drive assembly also includes a support frame (17) and a sliding assembly (18). The support frame (17) is disposed on one side of the connecting flange (20). The sliding assembly (18) is slidably disposed on the support frame (17) in the vertical direction and is connected to the connecting plate (23) to assist in the lifting and lowering of the fast Faraday cup.

10. The fast Faraday cup detector for a radio frequency ion implanter according to claim 8, characterized in that, The connecting flange (20) is also provided with a coaxial feed (21), which is connected to the microstrip line assembly (5) to realize the signal output of the microstrip line assembly (5).

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