Ionization device, ionization control method, and gas cluster ion beam production device

Abstract

An ionization device, an ionization control method and a gas cluster ion beam production device. The ionization device comprises an ionization cavity and an electron emission assembly. The ionization cavity comprises an ionization chamber and a channel constraint structure in the ionization chamber, the channel constraint structure is provided with a cluster channel penetrating in a first direction and a plurality of electron beam channels intersecting with the cluster channel and communicating, the central axes of the plurality of electron beam channels intersect on the central axis of the cluster channel. The electron emission assembly is arranged around the ionization chamber and corresponds to the electron beam channels one by one, and comprises an electron emission unit, an electron beam control unit and a focusing unit. The ionization device can significantly improve the ionization efficiency, reduce the ion beam energy dispersion and divergence, and reduce the equipment energy consumption through the design of the electron beam channel of the channel constraint structure matched with the multiple electron emission assemblies.

Description

Technical Field

[0001] This invention relates to the field of gas cluster ion beam production equipment technology, specifically to an ionization device, an ionization control method, and a gas cluster ion beam production equipment, which can be applied to fields such as material surface modification, semiconductor manufacturing, and integrated circuit processing. Background Technology

[0002] Gas Cluster Ion Beam (GCIB) technology is an advanced material surface modification technique that bombards material surfaces by ionizing and accelerating gas clusters to form an ion beam. This allows for nanoscale precision machining, surface smoothing, doping, and etching, with characteristics such as no subsurface damage and room temperature compatibility. This technology is widely used in semiconductor manufacturing, optics, aerospace, and other fields, especially in advanced integrated circuit node processes, where it has become a key support for overcoming traditional technological bottlenecks. Its applications cover core aspects of advanced CMOS logic, memory and novel device manufacturing, and interconnect processes. The ionization structure, as a core component of GCIB equipment, directly affects the overall processing performance of the equipment.

[0003] Existing GCIB devices generally suffer from the following technical problems in their ionization structures: First, the configuration of the electron emission source leads to uneven spatial distribution of the electron beam within the ionization region, resulting in a low probability of collision with gas clusters and low ionization efficiency. Second, the ionization chamber lacks an effective constraint and guidance mechanism for ion trajectory, resulting in significant energy dispersion and divergence of the ion beam after ionization, and insufficient stability. Third, the electron beam focusing control methods are limited, leading to low electron energy utilization. Fourth, the existing structures have high energy consumption, which does not conform to the development trend of energy conservation and environmental protection.

[0004] In view of this, it is necessary to provide an ionization device, an ionization control method, and a gas cluster ion beam production apparatus to at least solve one of the above-mentioned technical problems. Summary of the Invention

[0005] The purpose of this invention is to provide an ionization device, an ionization control method, and a gas cluster ion beam production apparatus, which can be applied to fields such as material surface modification, semiconductor manufacturing, and integrated circuit processing.

[0006] To achieve one of the above-mentioned objectives, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides an ionization device for a gas cluster ion beam production apparatus, comprising: an ionization chamber including an ionization chamber and a channel constraint structure located within the ionization chamber, wherein the channel constraint structure has a cluster channel extending along a first direction and a plurality of electron beam channels intersecting and communicating with the cluster channel, the central axes of the plurality of electron beam channels intersecting on the central axis of the cluster channel; a plurality of electron emission components disposed around the ionization chamber and corresponding one-to-one with the electron beam channels, each electron emission component including an electron emission unit, an electron beam control unit, and a focusing unit; the electron emission unit is configured to emit electrons after being powered on; the electron beam control unit is configured to constrain the electron beam to emit toward the cluster channel after being powered on; the focusing unit is located between the electron beam control unit and the ionization chamber, the focusing unit having an electron passage hole corresponding to the electron beam channel, and the focusing unit, after being powered on, causes the electron beam to pass through the electron passage hole and the electron beam channel respectively into the cluster channel.

[0008] In some embodiments, the channel constraint structure includes an annular column surrounding the cluster channel, the electron beam channel extending radially along the cluster channel and penetrating the annular column.

[0009] In some embodiments, the channel constraint structure further includes a plurality of drainage walls extending outward from the outer surface of the annular column facing away from the cluster channel, wherein the region on the annular column between adjacent drainage walls has a third electron passage hole, and the gap between adjacent drainage walls and the third electron passage hole together constitute the electron beam channel.

[0010] In some embodiments, the cluster channel is symmetrical about its central axis and has a smooth inner wall transition.

[0011] In some embodiments, the number of electron beam channels is N, and the N electron beam channels are uniformly arranged along the circumferential direction of the cluster channels.

[0012] In some embodiments, N is an even number, and the N electron beam channels are symmetrically arranged relative to the central axis of the cluster channels.

[0013] In some embodiments, the electron emission unit includes a hot cathode, at least a portion of which is disposed within the electron beam control unit, or at least a portion of which is disposed between the electron beam control unit and the focusing unit.

[0014] In some embodiments, the electron beam control unit is a suppressor electrode that at least partially surrounds the electron emission unit; or, the electron beam control unit includes a groove opening toward the focusing unit, and at least a portion of the hot cathode is disposed within the groove.

[0015] In some embodiments, the focusing unit includes an anode and a focusing electrode coaxially disposed inside the anode. The electron passage includes a first electron passage disposed on the anode and a second electron passage disposed on the focusing electrode. The first electron passage and the second electron passage correspond to and are coaxially disposed with the electron beam channel.

[0016] In some embodiments, the aperture of the first electron passage is not greater than the aperture of the second electron passage, and the aperture of the second electron passage is not greater than the inner diameter of the electron beam channel.

[0017] In some embodiments, the anodes of a plurality of electron emission components collectively form an annular anode, and a plurality of first electron passage holes are uniformly disposed on the annular anode; the focusing electrodes of a plurality of electron emission components collectively form an annular focusing electrode, and a plurality of second electron passage holes are uniformly disposed on the annular focusing electrode, the annular focusing electrode being coaxially disposed inside the annular anode, and the plurality of first electron passage holes and the plurality of second electron passage holes corresponding one-to-one with and coaxially disposed with respect to a plurality of electron beam channels; the electron beam control units of a plurality of electron emission components collectively form an annular suppressor electrode; the annular suppressor electrode is coaxially disposed outside the anode, and the annular suppressor electrode is located outside the first electron passage holes; the electron emission unit includes a hot cathode, and the hot cathodes of a plurality of electron emission components correspond one-to-one with the first electron passage holes.

[0018] In some embodiments, the annular suppressor has a groove recessed in the direction away from the ionization chamber and a through hole for the hot cathode to extend into the groove, the through hole being through in a first direction; the electron emission assembly further includes a pair of fixing rings respectively disposed on both sides of the annular suppressor in the first direction, the two ends of the hot cathode being respectively fixed to the two fixing rings, and the hot cathode passing through the through hole and through the groove.

[0019] In some embodiments, a barrier structure is provided between the ionization cavity and any two adjacent electrically connected structures in the electron emission assembly to achieve at least one of electrical isolation and physical limitation.

[0020] In some embodiments, the ionization device further includes a power supply module configured to provide the electron emission unit with a heating current of 80A to 100A and a floating voltage of -1000V to 0V.

[0021] In some embodiments, the ionization device further includes a power supply module, the focusing unit includes an annular anode and a focusing electrode coaxially disposed inside the anode, and the power supply module is configured to provide a higher potential to the focusing electrode than to the anode.

[0022] In some embodiments, the power supply module is configured to provide a voltage of 0V to 500V to the anode and a voltage of 0V to 2000V to the focusing electrode.

[0023] In some embodiments, the ionization device further includes a repulsion electrode disposed at the inlet end of the ionization chamber, the repulsion electrode being insulated from the ionization cavity, and the repulsion electrode having a first cluster passage hole extending along a first direction and communicating with the cluster channel; the ionization device further includes a power supply module electrically connected to the repulsion electrode, the power supply module being configured to output an independently adjustable compensation voltage to the repulsion electrode to construct an equipotential region within the ionization chamber.

[0024] In some embodiments, the ionization device further includes an ion guiding mechanism disposed at the outlet end of the ionization chamber, the ion guiding mechanism having a second cluster passage hole extending along a first direction and communicating with the cluster channel; the ion guiding mechanism is configured to provide a negative potential after being energized, so as to form an axial accelerating electric field between itself and the ionization chamber for drawing out positive ions, the negative potential being a voltage from 0V to -2000V.

[0025] In some embodiments, the ionization device further includes a repulsion electrode, an ion guiding mechanism, and a power supply module electrically connected to both the repulsion electrode and the ion guiding mechanism; the repulsion electrode is disposed at the inlet end of the ionization chamber, and the repulsion electrode has a first cluster passage hole that extends along a first direction and communicates with the cluster channel; the ion guiding mechanism is disposed at the outlet end of the ionization chamber, and the ion guiding mechanism has a second cluster passage hole that extends along the first direction and communicates with the cluster channel; the central axes of the first cluster passage hole, the cluster channel, and the second cluster passage hole are aligned, the diameter of the first cluster passage hole is less than or equal to the inner diameter of the cluster channel, and the diameter of the second cluster passage hole is greater than or equal to the inner diameter of the cluster channel.

[0026] In some embodiments, the repulsion electrode includes a first electrode plate and a first convex ring protruding from the first electrode plate toward the cluster channel, the first convex ring being disposed around the first cluster through hole; the ion guiding mechanism includes a second electrode plate and a second convex ring protruding from the second electrode plate toward the cluster channel, the second convex ring being disposed around the second cluster through hole, the surface of the second convex ring away from the second cluster through hole being arc-shaped.

[0027] Secondly, the present invention also provides a gas cluster ion beam production apparatus, including the aforementioned ionization device.

[0028] Thirdly, the present invention also provides an ionization control method applicable to any of the above-mentioned ionization devices, comprising the following steps: applying an electrical signal to the electron emission unit to generate a plurality of electron beams; applying an electrical signal to the electron beam control unit to constrain the electron beams to be emitted toward the cluster channel; applying an electrical signal to the focusing unit to focus the electron beams, causing the plurality of electron beams to enter the cluster channel through the plurality of electron beam channels respectively, and causing the central axes of the plurality of electron beams to intersect on the central axis of the cluster channel.

[0029] In some embodiments, the ionization device further includes a repulsion electrode disposed at the inlet of the ionization chamber; the ionization control method further includes applying a compensation voltage to the repulsion electrode to create an equipotential region within the ionization chamber.

[0030] In some embodiments, the electron emission unit is a hot cathode, to which a heating current of 80A to 100A and a floating voltage of -1000V to 0V are provided.

[0031] In some implementations, a more negative electrical signal than that of the electron emission unit is applied to the electron beam control unit to form an electrostatic repulsion field, thereby confining the electron beam to the cluster channel.

[0032] In some embodiments, the focusing unit includes an anode and a focusing electrode coaxially disposed inside the anode. The anode has a first electron passage hole, and the focusing electrode has a second electron passage hole corresponding to the first electron passage hole. The control method includes providing a voltage of 0V to 500V to the anode and a voltage of 0V to 2000V to the focusing electrode.

[0033] The beneficial effects of this invention are as follows: The ionization structure of this invention, by setting a channel constraint structure within the ionization chamber, ensures that the central axes of several electron beam channels substantially intersect on the central axis of the cluster channel. This results in the electron beam current density being superimposed and enhanced at the intersection point, forming a locally high-density electron cloud. When the neutral cluster beam passes through this intersection point axially, the probability of collision with electrons is significantly increased. Based on the intersecting design of several electron beam channels and cluster channels, ionization efficiency can be improved under the same electron beam current intensity; or, under the condition of achieving the same degree of ionization, the electron beam current intensity can be reduced, i.e., the current of the electron emission unit can be reduced, extending its service life. Furthermore, it can reduce bombardment damage caused by the electron beam to surrounding components (such as the chamber wall and channel constraint structure).

[0034] The electron beam control unit and focusing unit work together to flexibly adjust the intensity and focusing accuracy of the electron beam, adapting to cluster beams of different particle sizes and types. Combined with the electron beam channel, it guides and directs the electron beam, improving its arrival efficiency within the ionization chamber and cluster channel, and increasing the probability of collisions between electrons and the cluster beam. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the ionization device according to a preferred embodiment of the present invention.

[0036] Figure 2 for Figure 1 A diagram from another angle.

[0037] Figure 3 for Figure 1 A cross-sectional view along the AA direction.

[0038] Figure 4 for Figure 1 A cross-sectional view along the BB direction.

[0039] Figure 5 for Figure 1 A sectional view along the CC direction.

[0040] Figure 6 for Figure 1 The exploded diagram.

[0041] Figure 7 for Figure 6 A schematic diagram of the decomposition of D in the diagram.

[0042] Figure 8 for Figure 7 A cross-sectional view along FF from center E.

[0043] Figure 9 for Figure 7 A schematic diagram of the decomposition of E in the middle.

[0044] Figure 10 for Figure 9 A 3D diagram of G.

[0045] Figure 11 for Figure 10 A diagram from another angle.

[0046] Figure 12 for Figure 11 The exploded diagram.

[0047] Figure 13 for Figure 12 A decomposition diagram of H in the middle.

[0048] Figure 14 for Figure 12 A decomposition diagram of I.

[0049] Figure 15 The modeling and analysis of the potential distribution in the ionization chamber are illustrated. (a) shows the model structure of the ionization chamber, and (b) shows the potential distribution in the ionization chamber. The extra lines in (a) are equipotential lines.

[0050] Figure 16 The values ​​are simulated energy dissipation values ​​before and after applying a compensation voltage to the repulsive electrode. (a) is the simulated value without applying a compensation voltage to the repulsive electrode, and (b) is the simulated value without applying a compensation voltage to the repulsive electrode.

[0051] Figure 17 The diagrams show the simulation of the ionization chamber and the ion guiding mechanism. (a) is a simulation of the structure of the ion guiding mechanism using a three-stage electrode, and (b) is a diagram showing the trajectory distribution of the extracted ion beam.

[0052] Figure 18 for Figure 17 Based on this, the phase space distribution diagram of the ion beam is derived.

[0053] Figure 19 for Figure 17 The angular dispersion distribution of the ion beam is derived from this.

[0054] Among them, 100-ionization device, 1-ionization cavity, 11-first wall, 12-second wall, 13-channel constraint structure, 130-cluster channel, 131-annular column, 132-draining wall, 133-third electron passage hole, 134-electron beam channel, 2-electron emission assembly, 21-electron emission unit, 211-thermal cathode, 212-fixing ring; 22-electron beam control unit, 221-groove, 222-perforation, 23-focusing unit, 231-anode, 2311-first electron passage hole, 232-focusing electrode, 2321-second electron beam channel. 3-Ion through hole; 4-Repulsion electrode; 5-First electrode plate; 6-First convex ring; 7-First cluster through hole; 8-Ion guiding mechanism; 9-Second electrode plate; 10-Second convex ring; 11-Second cluster through hole; 12-Blocking structure; 13-First blocking structure; 14-First limiting groove; 15-Second blocking structure; 16-Second limiting groove; 17-Second limiting groove; 18-Second limiting groove; 19-Second limiting groove; 20-Second cluster through hole; 21-Second ion guiding mechanism; 22-Second electrode plate; 33-Second convex ring; 40-Second cluster through hole; 21-Second cluster through hole; 22-Second limiting groove; 33-Third blocking structure; 44-Third limiting groove; 55-Fourth blocking structure; 51-First limiting groove; 511-First limiting groove; 52-Second blocking structure; 521-Second limiting groove; 53-Third blocking structure; 531-Third limiting groove; 54-Fourth blocking structure; 541-Fourth limiting groove; 542-Support leg; 6-Outer shell; 61-Outer cylinder; 62-First outer wall; 63-Second outer wall. Detailed Implementation

[0055] The present invention will now be described in detail with reference to the specific embodiments shown in the accompanying drawings. However, these embodiments do not limit the present invention, and any structural, methodological, or functional modifications made by those skilled in the art based on these embodiments are included within the scope of protection of the present invention.

[0056] In the various figures of this invention, for ease of illustration, some dimensions of structures or parts may be exaggerated relative to other structures or parts; therefore, only the basic structure of the subject matter of this invention is used to illustrate the invention.

[0057] In traditional equipment, the technical problems existing in the ionization region not only restrict the engineering maturity and industrial competitiveness of GCIB equipment, but also make it difficult to match the core requirements of advanced integrated circuit manufacturing processes for low-damage, high-precision, and high-stability processing. This has become an important factor hindering the large-scale application of GCIB technology in the semiconductor industry and restricting the independent control of domestic advanced semiconductor manufacturing processes.

[0058] Based on this, the present invention aims to optimize the structure and control strategy of the GCIB ionization region, solve the pain points of low efficiency, poor beam current, insufficient stability and high damage risk of the existing ionization region, and propose an ionization device 100, an ionization control method and a gas cluster ion beam production device to improve the process adaptability and industrial applicability of GCIB equipment, which has urgent practical significance and industrial value.

[0059] Please refer to Figures 1 to 14 The diagram shows an ionization device 100 for a gas cluster ion beam production apparatus according to the present invention. The ionization device 100 includes an ionization chamber 1 and a plurality of electron emission components 2 disposed around the ionization chamber 1. The electron emission components 2 provide electron beams, which enter the ionization chamber 1 from different directions and ionize upon collision with the gas cluster beam (hereinafter referred to as the cluster beam) entering the ionization chamber 1.

[0060] For ease of description, the propagation direction of the gas cluster beam is defined as the first direction. Furthermore, the electrical terminology used in this invention is commonly used in the art. It is defined as follows: ionization efficiency refers to the percentage of ions produced by ionization to the number of incident gas clusters; energy divergence refers to the percentage of the standard deviation of the ion beam energy distribution to the average energy; divergence refers to the divergence angle of the ions, which can also be the tangent of the ion velocity to the parallel velocity (moving along the beam's central axis).

[0061] The ionization chamber 1 includes an ionization chamber and a channel constraint structure 13 located within the ionization chamber. The channel constraint structure 13 contains a cluster channel 130 extending along a first direction and several electron beam channels 134 intersecting and communicating with the cluster channel 130. The central axes of the several electron beam channels 134 intersect on the central axis of the cluster channel 130. By constraining electron beams from different directions through the electron beam channels 134, and converging them with the cluster beam at the same point or a very small area on the central axis of the cluster channel 130, the ionization region is highly concentrated, which can improve ionization efficiency. Furthermore, when the cluster beam is ionized at the central axis position, the ions generated by ionization mainly move along the axial direction, obtaining a smaller transverse velocity component, which can reduce the transverse energy dispersion of the ion beam.

[0062] The electron emission assembly 2 is disposed around the ionization chamber, and the emitted electron beam enters the cluster channel 130 through the electron beam channel 134. The electron emission assembly 2 includes an electron emission unit 21, an electron beam control unit 22, and a focusing unit 23.

[0063] The electron emission unit 21 is configured to emit electrons after being powered on, forming a continuous and stable electron beam.

[0064] The electron beam control unit 22 is configured to generate an electric field to confine the electron beam to the cluster channel 130 after being powered on.

[0065] A focusing unit 23 is disposed between the electron beam control unit 22 and the cluster channel 130. The focusing unit 23 has an electron passage hole corresponding to the electron beam channel 134. After being powered on, the focusing unit 23 causes (e.g., accelerates and guides) the electron beam to enter the cluster channel 130 through the electron passage hole and the electron beam channel 134, and focuses it at the intersection of the central axes of the multiple electron beam channels 134, further compressing the volume of the ionization region and avoiding beam divergence caused by the ionization position deviating from the central axis.

[0066] It should be noted that the electron emission unit 21, the electron beam control unit 22, and the focusing unit 23 can be electrically connected to a power supply module or to an external power supply. The power supply module or external power supply provides corresponding electrical signals to the electron emission unit 21, the electron beam control unit 22, and the focusing unit 23 relatively independently according to the function of each unit, facilitating individual control of electron beam generation and focusing, and improving flexibility and control accuracy.

[0067] The ionization device 100 of the present invention, based on the channel constraint structure 13, arranges the central axes of several electron beam channels 134 to intersect the central axis of the cluster channel 130, thereby enhancing the superposition of electron beam current density at the intersection point and forming a local high-density electron cloud. When the neutral cluster beam passes through this intersection point along the axial direction, the probability of collision with electrons is significantly increased. Based on the intersecting design of several electron beam channels 134 and cluster channel 130, ionization efficiency can be improved under the same electron beam current intensity; or, under the condition of achieving the same degree of ionization, the electron beam current intensity can be reduced, that is, the current of the electron emission unit 21 can be reduced, the service life can be extended, and the bombardment damage caused by the electron beam to surrounding components (such as the inner wall of the cavity and the channel constraint structure 13) can be reduced.

[0068] The electron beam control unit 22 and the focusing unit 23 work together to flexibly adjust the intensity and focusing accuracy of the electron beam, adapting to cluster beams of different particle sizes and types. Combined with the electron beam channel 134, they guide and direct the electron beam, improving its arrival efficiency within the ionization chamber and cluster channel 130, and increasing the probability of collisions between electrons and the cluster beam.

[0069] In this invention, the ionization chamber 1 is made of stainless steel, preferably 316L stainless steel. Stainless steel has good electrical conductivity and corrosion resistance, making it suitable for processing corrosive gases.

[0070] The surface of the ionization chamber 1 can be coated with an insulating coating to prevent corrosion and improve electrical insulation performance, thus preventing leakage between the ionization chamber 1 and other electrodes.

[0071] The insulating coating combines corrosion resistance and insulation functions, and can be selected from options such as alumina coatings. The thickness of the insulating coating should be 0.5 mm or more to ensure that the entire surface of the ionization chamber is covered with a complete and dense insulating coating.

[0072] The ionization chamber 1 includes a first wall 11 located at the inlet end of the ionization chamber and a second wall 12 located at the outlet end of the ionization chamber. Both the first wall 11 and the second wall 12 are provided with through holes that extend along a first direction, thereby defining the ionization chamber that extends along the first direction.

[0073] In some embodiments, the ionization chamber is preferably cylindrical, which can effectively avoid unnecessary collisions and charge loss between clustered beams, ions, and the cavity walls. Furthermore, the cylindrical shape of the ionization chamber eliminates sharp corners and plane boundaries, resulting in a more uniform electric field distribution and no sharp-corner electric field distortion.

[0074] In one embodiment, the inner diameter L1 of the ionization chamber is 50 mm, and the length L2 (the distance between the first wall 11 and the second wall 12) is 18 mm.

[0075] The channel constraint structure 13 is located in the ionization chamber, which defines the cluster channel 130 for the cluster beam to pass through and the electron beam channel 134, so that the electron beam and the cluster beam can be accurately intersected, thereby improving the ionization efficiency.

[0076] The channel constraint structure 13 and the ionization cavity 1 can be integrally formed without assembly. Alternatively, the channel constraint structure 13 and the ionization cavity 1 can be designed separately and then connected into one piece by welding or other methods.

[0077] In one embodiment, the channel constraint structure 13 is integrally formed with the second wall 12, while the channel constraint structure 13 is separately formed with the first wall 11 and then welded together. Alternatively, the channel constraint structure 13 is integrally formed with the first wall 11, while the channel constraint structure 13 is separately formed with the second wall 12 and then welded together.

[0078] The channel constraint structure 13 includes an annular column 131 that encloses and forms a cluster channel 130. An electron beam channel 134 is located within the annular column 131, extends radially along the cluster channel 130, and penetrates the annular column 131. The annular column 131 is located between a first wall 11 and a second wall 12, and is connected to the first wall 11 and the second wall 12.

[0079] The electron beam channel 134 extends radially along the cluster channel 130, which facilitates the emission of each electron beam directly onto the central axis of the cluster channel 130. When multiple electron beams are incident simultaneously along different radial directions (e.g., two, three, four, or six beams), their central axes converge at a point on the central axis of the cluster channel 130. This design avoids ionization region offset, thereby maximizing ionization efficiency and axial consistency of the ion beam. Furthermore, the radial perforations 222 on the annular body can be formed in one step on the annular column 131 using conventional drilling processes, reducing the processing difficulty and manufacturing cost of the channel constraint structure 13. Simultaneously, it facilitates ensuring the positional accuracy and coaxiality of the multiple electron beam channels 134 during manufacturing, improving product yield and consistency.

[0080] In one embodiment, the channel constraint structure 13 includes an annular column 131 that surrounds and forms a cluster channel 130, and a plurality of drainage walls 132 extending outward from the outer surface of the annular column 131 facing away from the cluster channel 130.

[0081] The drainage wall 132 and the annular column 131 can be integrally formed, resulting in a stable structure without any joints, thus avoiding local electric field distortion. Alternatively, the drainage wall 132 and the annular column 131 can be separately formed and then connected into a single unit, facilitating manufacturing.

[0082] The channel constraint structure 13 and the drainage wall 132 are both located between the first wall 11 and the second wall 12, and the annular column 131 and the drainage wall 132 are both connected to the first wall 11 and the second wall 12.

[0083] The region on the annular column 131 between adjacent drainage walls 132 has a third electron passage hole 133, and the gap between adjacent drainage walls 132 and the third electron passage hole 133 together form an electron beam channel 134.

[0084] After the electron beam enters the ionization chamber, it first passes through the gap between adjacent guide walls 132. This gap restricts the divergence space of the electron beam in the radial and circumferential directions, enabling the electron beam to accurately enter the third electron passage hole 133 on the annular column 131 at the correct incident angle.

[0085] This guided-beam-at-the-fly electron beam channel 134 effectively compensates for trajectory deviations that may occur during electron beam transmission due to space charge effects or external stray fields. This ensures the electron beam accurately passes through the relatively long electron beam channel 134 and reaches the central axis of the cluster channel 130. The electron beam that ultimately enters the ionization region has a smaller divergence angle and higher directional consistency, further compressing the volume of the ionization region, thereby reducing lateral energy dispersion of the ion beam and improving the quality of the final output ion beam.

[0086] In this invention, the cluster channel 130 is symmetrical about its central axis, and its inner wall has a smooth transition, with no abrupt structural changes (e.g., step-like abrupt changes) along the axial and circumferential directions. The cluster beam is unaffected by asymmetric geometry during transmission, avoiding cluster scattering, aggregation, or breakup caused by irregular channel morphology. This results in a highly axisymmetric density and velocity distribution for the cluster beam entering the ionization region, laying the foundation for maintaining excellent beam quality in the subsequent ion beam. Furthermore, the electric field within the cluster channel 130 is also axisymmetric, applying a uniform radial force to the ions generated after ionization. This effectively confines the ions near the central axis and extracts them axially, avoiding lateral drift or loss of ions due to electric field distortion, thereby improving ion extraction efficiency and beam transmission efficiency.

[0087] In some embodiments, the cluster channel 130 is preferably a cylindrical channel, which can effectively avoid unnecessary collisions and charge loss between ions and the channel wall. The cylindrical channel has no sharp corners or plane boundaries, resulting in a more uniform electric field distribution and no sharp-corner electric field distortion.

[0088] The radial direction of the cluster channel 130 is defined as the second direction. It is understood that the second direction is not a definite direction, but rather a collective term for a series of directions radiating radially outward from the cluster channel 130 as its central axis. The second direction is perpendicular to the first direction. Several electron beam channels 134 extend along different second directions arranged circumferentially around the cluster channel 130, and the central axes of these electron beam channels 134 intersect at a point on the central axis of the cluster channel 130.

[0089] In this invention, the inner diameter of the electron beam channel 134 is matched with the aperture of the electron passage hole, so that the focused electron beam can pass through the channel constraint structure 13 without obstruction and collide precisely with the cluster beam.

[0090] In one embodiment, the inner diameter L3 (inner diameter of cluster channel 130) of channel constraint structure 13 is about 6 mm, and the aperture of third electron passage hole 133 is about 10 mm.

[0091] The number of electron beam channels 134 is N, and the N electron beam channels 134 are uniformly arranged along the circumference of the cluster channel 130. The included angle between adjacent electron beam channels 134 is 360° / N.

[0092] When multiple electron beams simultaneously enter the central axis of cluster channel 130 from different directions, an electron cloud composed of superimposed electron beams from multiple directions is formed near the intersection of the central axes. The uniform circumferential distribution ensures that the electron cloud has an isotropic spatial distribution in a plane perpendicular to the axis, allowing clusters passing through this region to achieve similar ionization probabilities regardless of the direction from which they approach. This isotropic ionization environment significantly improves the uniformity of ionization and avoids directional deviations in the ion beam caused by unilateral ionization.

[0093] In an optional embodiment, N is an even number, and the N electron beam channels 134 are symmetrically arranged with respect to the central axis of the cluster channel 130. Each electron beam channel 134 has a corresponding electron beam channel 134 that is symmetrical about the central axis. The two symmetrical electron beams are incident at the same angle but in opposite radial directions.

[0094] Electron beams carry momentum, and when incident from one side, they can cause lateral momentum transfer to the cluster beam, potentially leading to deviation from the central axis. A symmetrical arrangement ensures that the momentum vectors of each pair of electron beams are equal in magnitude and opposite in direction, canceling each other out at the central axis. This momentum balance design effectively suppresses lateral disturbances to the cluster beam from the electron beam, ensuring that both the neutral cluster beam and the ionized ion beam propagate stably along the central axis. This is particularly suitable for applications requiring extremely high beam pointing accuracy.

[0095] The symmetrically arranged electron beam channel 134 ensures that the space charge field generated by the electron beam in the ionization region also exhibits symmetry. During ionization, the space charge carried by the electron beam forms a certain potential distribution in the ionization region. When the electron beam is symmetrically incident, this potential distribution exhibits axial symmetry in a plane perpendicular to the central axis, and no deflection electric field is generated. This ensures that the ionized ions are not subjected to asymmetrical transverse electric forces when leaving the ionization region, thus maintaining the axial direction of the ion beam. This characteristic is crucial for subsequent ion beam acceleration, focusing, and mass analysis.

[0096] Furthermore, when the number of electron beam channels 134 is even and they are symmetrically arranged, the operating parameters (emission current, control voltage, focusing voltage) of the two sets of electron emission components 2 at symmetrical positions are theoretically the same. Therefore, a one-to-one power supply method can be adopted, connecting the two symmetrical sets in parallel and driving them with the same power supply, thereby reducing the number of channels in the power supply module, simplifying circuit design and wiring, and reducing the hardware cost and failure rate of the system.

[0097] In one embodiment, N is 6, and the angle between adjacent electron beams is 60°. The electron emission assembly 2 emits electron beams simultaneously from six directions to bombard the cluster beam within the cluster channel 130, significantly improving ionization efficiency.

[0098] In other embodiments, N can also be 4 or 8. The more electron beams there are, the lower the average current intensity required for each electron beam, thus allowing for a suitable reduction in the current of the electron emission unit 21, which in turn lowers the temperature of the electron emission unit 21 (e.g., a tungsten filament) and results in a longer operating life.

[0099] Several electron emission components 2 are arranged around the ionization chamber and correspond one-to-one with the electron beam channel 134, emitting electron beams from the surrounding area into the cluster channel 130. After being focused into the ionization chamber, the electron beams pass through the electron beam channel 134 and enter the cluster channel 130.

[0100] Electron emission unit 21 includes a thermionic cathode 211, which generates thermionic emission when heated by an electric current. For clarity of the other structures, only... Figure 7 The hot cathode 211 is shown in the figure; the hot cathode 211 is omitted in other figures.

[0101] In some embodiments, at least a portion of the electron emission unit 21 is disposed within the electron beam control unit 22, meaning that at least a portion of the hot cathode 211 is surrounded by the electron beam control unit 22. Electrons emitted from the hot cathode 211 immediately enter the effective region of the electron beam control unit 22. The electron beam control unit 22 constrains the electron beam from the emission source, effectively suppressing the inherent initial velocity dispersion and space charge divergence effects during hot electron emission, enabling the electron beam to obtain good directionality in the early stages of formation and be emitted towards the central axis of the cluster channel 130. Simultaneously, the electron beam control unit 22 can also serve as a thermal radiation barrier layer. On the one hand, it reduces temperature fluctuations in the hot cathode 211 caused by airflow disturbances within the cavity, improving the long-term stability of the emission current; on the other hand, it reduces heat conduction and radiation to the focusing unit 23 and the ionization cavity 1, protecting the precision electrode structure of the focusing unit 23 from thermal damage.

[0102] In an optional embodiment, the hot cathode 211 extends into the electron beam control unit 22 and emits electrons after being energized.

[0103] In some embodiments, at least a portion of the electron emission unit 21 is disposed between the electron beam control unit 22 and the focusing unit 23. The emitted electrons are directed toward the central axis of the cluster channel 130 under the control of the electron beam control unit 22, and are focused by the focusing unit 23 to reach the central axis of the cluster channel 130.

[0104] In an optional embodiment, the hot cathode 211 extends between the electron beam control unit 22 and the focusing unit 23 and emits electrons after being energized.

[0105] In some embodiments, the electron emission assembly 2 further includes a pair of fixing rings 212, with the two ends of the hot cathode 211 respectively fixed on the two fixing rings 212, and the middle part of the hot cathode 211 disposed in the electron beam control unit 22 (e.g., the suppressor electrode) or between the electron beam control unit 22 and the focusing unit 23.

[0106] In one embodiment, the hot cathode 211 is filamentous and heats up and emits electrons when voltage and current are applied.

[0107] When the fixing ring 212 is a conductive ring, for example, made of 316L stainless steel, several hot cathodes 211 are connected in parallel to the fixing ring 212, and can be connected to the power supply module or external power supply through the fixing ring 212. Several hot cathodes 211 can also be directly fixed to the power supply module or external power supply, so the material of the fixing ring 212 can be extended to a non-conductive material.

[0108] A plurality of thermionic cathodes 211 constitute an emission source, which are arranged one-to-one with the electron beam channel 134 along the radial direction of the cluster channel 130. After being energized, the plurality of thermionic cathodes 211 emit electrons, which are formed under the action of the electron beam control unit 22 and the focusing unit 23, and reach the central axis of the cluster channel 130 through the electron beam channel 134.

[0109] Preferably, a plurality of hot cathodes 211 are uniformly arranged along the fixing ring 212, and the electrons are continuously distributed in the circumferential direction. Combined with the constraints of the electron beam control unit 22 and the focusing of the anode 231 and the focusing electrode 232, it is ensured that each electron beam (corresponding to each electron through-hole) has the same emission characteristics and focusing state. This structure avoids the inconsistencies between the electron beams of the discrete electron emission units 21, and is beneficial to the symmetry and uniformity of multiple electron beams when they intersect on the central axis.

[0110] In some embodiments, the thermionic cathode 211 is made of tungsten wire. Tungsten wire has the characteristics of long life, high temperature resistance, and high electron emission efficiency, which can ensure the long-term stability of electron emission.

[0111] The diameter of the tungsten wire is 0.2 mm to 0.5 mm, and the effective heating length (the length extending into the electron beam control unit 22 or located between the electron beam control unit 22 and the focusing unit 23) is 10 mm to 20 mm, for example, 15 mm to 20 mm or 10 mm to 15 mm.

[0112] In other embodiments, the hot cathode 211 may also be a filament made of materials such as lanthanum hexaboride or barium oxide.

[0113] The electron beam control unit 22 at least partially surrounds the hot cathode 211. "Surrounding" here means that the electron beam control unit 22 encloses the hot cathode 211, or that the electron beam control unit 22 surrounds the hot cathode 211 within a space. The electron beam control unit 22 forms an electrostatic shield and direction guide for the electrons emitted from the hot cathode 211, constraining the electron beam to be emitted into the cluster channel 130 through the focusing unit 23.

[0114] In some embodiments, the electron beam control unit 22 is a suppressor. Preferably, the electron beam control units 22 of several electron emission components 2 together form a ring-shaped suppressor.

[0115] In some embodiments, the electron beam control unit 22 includes a groove 221 opening toward the focusing unit 23, and at least a portion of the hot cathode 211 is disposed within the groove 221. Preferably, the electron beam control units 22 of a plurality of electron emission components 2 collectively form an annular suppressor, and the grooves 221 of the plurality of electron beam control units 22 form an annular groove.

[0116] An annular suppressor is coaxially disposed outside the anode 231, and is located outside the first electron passage hole 2311. The annular suppressor has an annular groove 221 recessed in the direction away from the ionization chamber, and a through hole 222 extending into the groove 221 from the heating cathode 211, the through hole 222 being through in the first direction. That is, the groove 221 is annular and opens towards the ionization chamber, and the two groove walls of the annular suppressor disposed opposite to each other in the first direction have through holes 222 extending in the first direction.

[0117] Several electron emission units 21 have their hot cathodes 211 extending into the groove 221. The emitted electrons are constrained by the ring-shaped suppressor and transported to the central ionization chamber.

[0118] A pair of fixing rings 212 are respectively disposed on both sides of the annular suppressor in the first direction. The two ends of the hot cathode 211 are respectively fixed on the two fixing rings 212, and the middle part of the hot cathode 211 passes through the groove 221 through the through hole 222. Several hot cathodes 211 correspond one-to-one with electron passage holes.

[0119] A ring-shaped suppressor electrode applies a negative potential relative to the thermionic cathode 211, and its ring structure allows it to surround the emission source of the electron emission unit 21 in all directions. Electrons emitted from the thermionic cathode 211 have isotropic initial velocities when they leave the surface of the thermionic cathode 211. The negative potential field generated by the ring-shaped suppressor electrode exerts a centripetal force on the electrons, pushing the electrons that would otherwise diverge in all directions back into the axial direction, so that the electron beam obtains a smaller divergence angle before entering the focusing unit 23. This constraint effect can improve the electron beam capture efficiency of the focusing unit 23, reduce beam loss caused by electron beam divergence, and thus obtain a greater electron beam current intensity reaching the ionization region under the same emission current of the thermionic cathode 211.

[0120] In addition, the annular suppressor ensures that the electron beam is uniformly constrained in the circumferential direction, which is well matched with the uniform circumferential layout of the electron beam channel 134 along the cluster channel 130, ensuring that multiple electron beams have consistent directionality and focusing state before entering their respective electron beam channels 134.

[0121] Several focusing units 23 are arranged in a ring and coaxially between the electron beam control unit 22 and the ionization chamber. Each focusing unit 23 includes an anode 231 and a focusing electrode 232, with the focusing electrode 232 coaxially disposed inside the anode 231. Electron passages include a first electron passage 2311 disposed on the anode 231 and a second electron passage 2321 disposed on the focusing electrode 232. The first electron passage 2311 and the second electron passage 2321 correspond one-to-one with the electron beam channel 134.

[0122] Relative to the electron emission unit 21, the anode 231 is subjected to a positive high voltage, and the electron beam passes through the first electron through hole 2311 and is transmitted towards the ionization chamber, while also playing a preliminary focusing role.

[0123] When the focusing electrode 232 is energized, it forms a focusing electric field, which can further compress the divergence angle of the electron beam, so that the electron beam is concentrated on the ionization region of the cluster beam.

[0124] Compared to single-electrode focusing, the anode 231 and the focusing electrode 232 form a dual-electrode focusing structure, which has stronger focusing ability and a shorter focal length, and can focus the electron beam onto the central axis of the cluster channel 130 in a very short distance.

[0125] Furthermore, the anode 231 and the focusing electrode 232 are powered separately, allowing for independent potential adjustment. The anode 231 primarily performs the acceleration function, determining the energy of the electron beam. The focusing electrode 232 performs the focusing function, determining the beam waist position and beam spot size. Independent power supply for both achieves decoupling between acceleration and focusing. During ionization, the voltage of the anode 231 can be set to determine the electron energy based on process requirements such as the electron energy requirements of different cluster types and sizes. Then, the voltage of the focusing electrode 232 can be independently adjusted to optimize the focusing effect, improving the process adaptability of the device.

[0126] The anode 231 and the focusing electrode 232 are coaxially arranged to ensure the axial symmetry of the focusing electric field, so that the electron beam is subjected to a uniform focusing force in the circumferential direction, avoiding beam spot distortion caused by asymmetric focusing.

[0127] Under the action of the electron beam control unit 22 and the focusing unit 23, the electron beam passes through the first electron passage hole 2311, the second electron passage hole 2321, and the electron beam channel 134 in a straight line and enters the cluster channel 130.

[0128] In an optional configuration, the first electron passage hole 2311 and the second electron passage hole 2321 are coaxially arranged with the electron beam channel 134 to facilitate the smooth passage of the electron beam into the ionization chamber.

[0129] The aperture of the first electron through aperture 2311 is no larger than the aperture of the second electron through aperture 2321, and the aperture of the second electron through aperture 2321 is no larger than the inner diameter of the electron beam channel 134. A non-decreasing aperture gradient is achieved along the electron beam propagation direction.

[0130] A non-decreasing aperture gradient can minimize stray or scattered electrons that deviate from the axis, ensuring that electrons with good orientation and correct trajectory can reach the central axis of the cluster channel 130 as comprehensively as possible, thereby improving the purity and directional consistency of the electron beam reaching the ionization region.

[0131] The non-decreasing aperture gradient also ensures that the electron beam can be transmitted with as little obstruction as possible, such as passing through each level of aperture without collision, so as to efficiently transfer the energy of the electron beam to the ionization region, while reducing secondary electron pollution and thermal damage caused by the electron beam bombarding the electrodes, and extending the service life of components such as the focusing unit 23.

[0132] For example, if the aperture of the first electron passage hole 2311 is not larger than the aperture of the second electron passage hole 2321, the bombardment of the end face of the focusing electrode 232 by the electron beam accelerated and pre-focused by the anode 231 can be reduced or avoided, thus reducing or avoiding unnecessary secondary electron emission and the resulting local overheating of the focusing electrode 232.

[0133] In one embodiment, the aperture of the first electron passage 2311 is 8 mm to 10 mm, for example, 9 mm. The thickness of the anode 231 in the second direction is 5 mm to 7 mm, for example, 6 mm. The aperture of the second electron passage 2321 is 5 mm to 7 mm, and the thickness of the focusing electrode 232 in the second direction is 5 mm to 8 mm, for example, 6 mm.

[0134] In some embodiments, a plurality of electron beam control units 22 together constitute an annular suppressor. The groove 221 of the annular suppressor is annular and faces the opening of the ionization chamber. The two groove walls of the annular suppressor, which are arranged opposite each other in a first direction, have through holes 222 that extend through the first direction.

[0135] Several electron emission components 2 have their anodes 231 forming a ring anode, and several first electron passage holes 2311 are uniformly disposed on the ring anode. Several electron emission components 2 have their focusing electrodes 232 forming a ring focusing electrode, and several second electron passage holes 2321 are uniformly disposed on the ring focusing electrode. The ring focusing electrode is coaxially disposed inside the ring anode, and the several first electron passage holes 2311 and several second electron passage holes 2321 correspond one-to-one with several electron beam channels 134 and are coaxially disposed.

[0136] Along the electron beam emission direction, the annular suppressor, annular anode, and annular focusing electrode are coaxially arranged in sequence, resulting in a coaxial circular layout for the electron emission assembly 2, which has a compact structure. Specifically, the annular focusing electrode is coaxially disposed on the outer layer of the ionization chamber, and the second electron passage hole 2321 is aligned with the electron beam channel 134 along the second direction. The annular anode is coaxially disposed on the outside of the annular focusing electrode, and several first electron passage holes 2311 and several second electron passage holes 2321 are aligned along the second direction. The annular suppressor is coaxially disposed on the outside of the annular anode, and the annular suppressor is located outside the first electron passage hole 2311.

[0137] The emission source of the electron emission unit 21 is a thermionic cathode 211, and several thermionic cathodes 211 are fixed in parallel on two fixing rings 212. Specifically, the two fixing rings 212 are located on both sides of the annular suppressor in the first direction, and the thermionic cathodes 211 extend into the groove 221 of the annular suppressor through the through hole 222 along the first direction.

[0138] By integrating multiple electron emission components 2 into a single unit through a fixing ring 212, an annular suppressor electrode, an annular anode, and an annular focusing electrode, the alignment and installation difficulty of each component is simplified, and the alignment accuracy is improved.

[0139] Of course, several electron emission components 2 can also be installed independently around the ionization chamber in a uniform circumferential direction, while simultaneously emitting electron beams into the ionization chamber.

[0140] Based on any of the above-mentioned ionization devices 100, it also includes a power supply module for providing electrical signals to structures that require power.

[0141] For example, the power supply module supplies power to the electron emission assembly 2. The power supply module is electrically connected to the electron emission unit 21, the electron beam control unit 22, and the focusing unit 23, and provides corresponding electrical signals to the electron emission unit 21, the electron beam control unit 22, and the focusing unit 23 relatively independently according to the function of each unit.

[0142] In this invention, the electrical signal may include a continuous DC electrical signal or a pulse-modulated electrical signal.

[0143] The power supply module is configured to provide a heating current within a preset current range to the electron emission unit 21. The electron emission unit 21 is a thermionic cathode 211, and its emission current density is exponentially related to the heating temperature. The heating current within the preset current range ensures that the operating temperature range of the electron emission unit 21 (e.g., a tungsten filament) is within the saturation region of thermionic emission. When operating in the saturation region, the electron beam intensity is mainly determined by the suppressor electrode, the focusing unit 23 (anode 231 and focusing electrode 232), and their voltage. It is insensitive to fluctuations in the temperature of the thermionic cathode 211 (i.e., the tungsten filament heating current) and has a natural ability to suppress external electromagnetic interference and power supply ripple. This ensures the high stability of the electron beam intensity during long-term operation and avoids ionization efficiency drift caused by emission fluctuations.

[0144] In some implementations, taking the hot cathode 211 as a tungsten filament as an example, the power supply module is configured to provide the electron emission unit 21 with a heating current of 80A to 100A and a floating voltage of -1000V to 0V.

[0145] At heating currents of 80A to 100A, the temperature is approximately 2000K to 2300K, which is within the saturation region of tungsten filament thermionic emission. Below 80A, the emission current density is insufficient to meet the requirements for high ionization efficiency. Above 100A, the tungsten filament evaporation rate increases sharply, significantly shortening its lifespan. This parameter range ensures sufficient emission capability while extending the expected lifespan of the thermionic cathode 211, reducing the frequency of consumable replacements and operating costs.

[0146] The power supply module is configured to simultaneously provide a floating voltage within a preset voltage range to the electron emission unit 21. The floating voltage refers to the bias voltage of the electron emission unit 21 relative to the ground potential. The floating power supply method cuts off the path between the thermionic cathode 211 and the ground where the equipment is located, minimizing interference introduced by the grounding loop, improving the signal-to-noise ratio of the emission current, and facilitating the acquisition of a clean electron beam.

[0147] The negative suspension potential places the hot cathode 211 at a more negative potential relative to the anode 231 and the focusing electrode 232, or the ionization chamber. This repels secondary electrons returning from the focusing unit 23 or the ionization chamber, preventing them from bombarding the cathode surface and causing emission attenuation or sputtering contamination. By adjusting the suspension voltage, the energy of the electron beam can be controlled to a certain extent without changing the voltage of the anode 231.

[0148] Ionization energy is precisely controlled by heating current and floating voltage. The greater the voltage difference applied to the hot cathode 211, the greater the current generated on the hot cathode 211, which can increase electron emission density and enhance ionization intensity.

[0149] The power supply module is configured to provide a higher potential to the focusing electrode 232 than to the anode 231, thereby creating a focusing electric field. When electrons move from the anode 231 to the focusing electrode 232, they are subjected to a radial converging force. Furthermore, the high potential of the focusing electrode 232 can also repel ions generated in the ionization region, preventing ions from escaping from the cluster channel 130 and improving ion extraction efficiency.

[0150] The power supply module is configured to provide a greater potential range to the focusing electrode 232 than to the anode 231, thereby creating a width-adjustable potential difference between the anode 231 and the focusing electrode 232. This wide adjustment range allows the focal length of the focusing unit 23 to be continuously varied from "long focal length" (small potential difference) to "short focal length" (large potential difference), ensuring that the focusing unit 23 can precisely adjust the beam waist of the electron beam to the central axis of the cluster channel 130 regardless of how the anode 231 voltage is set.

[0151] The intensity and focusing effect of the electron beam can be precisely controlled by adjusting the voltage of the anode 231 and the focusing electrode 232. For example, keeping the potential of the anode 231 constant ensures that the energy of the electron beam remains constant; adjusting the potential of the focusing electrode 232 changes the focusing intensity.

[0152] In one embodiment, the power supply module provides an electrical signal with an effective value of 0V to 500V, such as a DC voltage of 0V to 500V, to the anode 231. The power supply module provides an electrical signal with an effective value of 0V to 2000V, such as a DC voltage of 0V to 2000V, to the focusing electrode 232.

[0153] Based on any of the above-described ionization devices 100, it further includes a repulsion electrode 3. The repulsion electrode 3 is disposed at the inlet end of the ionization chamber and is insulated from the ionization chamber 1. The repulsion electrode 3 has a first cluster through-hole 30 that extends along a first direction and communicates with the cluster channel 130, guiding the atomic cluster beam into the cluster channel 130.

[0154] The repulsion electrode 3 is disposed on the side of the first wall 11 facing away from the ionization chamber. The repulsion electrode 3 includes a first electrode plate 31 and a first protruding ring 32 protruding from the first electrode plate 31 facing away from the cluster channel 130. The first protruding ring 32 is disposed around the first cluster through hole 30.

[0155] The first convex ring 32 protrudes away from the cluster channel 130, that is, it extends outwards towards the ionization chamber. Through the first convex ring 32, without occupying the space of the ionization chamber, the axial length of the first cluster through hole 30 can be appropriately increased, which plays a guiding and constraining role for the central cluster beam, while resisting or accepting the impact of the outer clusters, thus improving the service life.

[0156] The thickness of the first convex ring 32 in the first direction is greater than the aperture of the first cluster passage hole 30. This greater thickness in the first direction effectively constrains the cluster, reducing turbulence and pressure fluctuations. When a compensation voltage is applied, a localized electric field enhancement occurs in the end region of the first convex ring 32, generating a stronger repulsive force. This electric field focusing effect causes the repulsive electrode 3 to exert a stronger repulsive effect on ions escaping upstream, effectively preventing ion backflow to the cluster source region. Simultaneously, the effective action area of ​​the repulsive electrode 3 is closer to the inlet of the cluster channel 130, reducing the length of the electric field transition region between the repulsive electrode 3 and the channel constraint structure 13, allowing the potential distribution to transition over a shorter distance.

[0157] In one embodiment, the diameter of the first cluster through the hole 30 is 5 mm to 7 mm, for example, 6 mm. The thickness of the first convex ring 32 in the first direction is 6 mm to 8 mm, for example, 7 mm.

[0158] Further research revealed that directly connecting the ionization chamber to a high voltage increases the suspended high voltage throughout the entire chamber. Because high voltage is applied to both the ionization region inside and outside the chamber, a potential decreases at the notch (the through-hole in the first wall 11 of the ionization chamber 1), creating a distorted electric field region. When the cluster beam passes through this distorted electric field region, it experiences trajectory deviation or velocity changes.

[0159] In this invention, the repulsion electrode 3 is configured to provide appropriate potential compensation after being energized, forming a potential distribution in the ionization chamber entrance region that matches the main electric field inside the ionization chamber, ensuring that the interior of the ionization chamber is an isopotential region (including an approximate isopotential region that has no substantial effect on ion beam deflection), so as to ensure that the central cluster beam enters the cluster channel 130 without disturbance at its original speed and direction, thereby reducing ion energy dispersion.

[0160] The repulsion electrode 3 is insulated from the ionization chamber 1, or the two are separated by an insulating block. The power supply module has a compensation output terminal that is independently electrically connected to the repulsion electrode 3, and is configured to apply a compensation voltage to the repulsion electrode 3 to compensate for the potential drop in the ionization chamber entrance region, so as to construct an approximately equipotential region in the ionization chamber, making the potential distribution in the ionization region uniform, thereby reducing the energy dispersion of the ion beam.

[0161] With the applied voltages to all other electrodes kept constant, the voltage of the repulsion electrode 3 was gradually increased from 0, and the intensity of the ion beam emitted from the ionization device 100 was measured to obtain a voltage-ion beam intensity curve. As the voltage of the repulsion electrode 3 increased, the ion beam intensity generally showed a trend of first increasing and then decreasing. When the ion beam intensity showed a clear and stable decreasing trend, the voltage applied to the repulsion electrode 3 was no longer increased, and the voltage corresponding to the maximum ion beam intensity was selected as the compensation voltage. For different target energies, the compensation voltage needs to be recalibrated.

[0162] The repulsion electrode 3 and the channel constraint structure 13 are located upstream and around the ionization region, respectively. The potentials applied by both work together to construct the overall electric field distribution within the ionization chamber. By independently adjusting the compensation voltage of the repulsion electrode 3, the electric field gradient upstream of the ionization region can be precisely controlled. This adjustment capability allows for the optimization of the equipotential surface within the ionization region, ensuring that the electric field direction within the ionization region primarily points towards the exit end, rather than diverging radially. The optimized electric field distribution enables the ions generated by ionization to immediately acquire an acceleration pointing towards the exit after formation, reducing the residence time of ions within the ionization region and lowering the probability of ion-ion recombination and ion-neutral cluster collisions, thereby improving the current intensity and purity of the ion beam.

[0163] The potential drop at the gas inlet of the ionization region is compensated by adjusting the potential of the repulsion electrode 3, resulting in a uniform potential distribution in the ionization region and thus reducing ion beam energy dispersion. The potential compensation process involves measuring the target current intensity with a zero compensation voltage, then continuously increasing the compensation voltage and recording the target current intensity to obtain a voltage-current intensity curve. The optimal voltage corresponds to the voltage with the maximum current intensity, and this voltage is set as the compensation voltage during operation. For different target energies, this optimal voltage needs to be recalibrated. By numerically solving the potential distribution in the ionization region and performing ion-by-ion tracking simulations, the final ion energy dispersion value obtained by continuously changing the compensation potential is <3 eV, while the value without compensation is 15 eV. This demonstrates the significant effect of the compensation electrode.

[0164] Based on any of the above-described ionization devices 100, it further includes an ion guiding mechanism 4. The ion guiding mechanism 4 is disposed at the outlet end of the ionization chamber. The ion guiding mechanism 4 has a second cluster through-hole 40 that extends along a first direction and communicates with the cluster channel 130, for guiding the ionized ion beam.

[0165] The ion guiding mechanism 4 is located on the side of the second wall 12 facing away from the ionization chamber. The size of the second cluster through the aperture 40 matches the size of the ion beam, which can accurately guide and constrain the ion beam after ionization, reduce the divergence of the ion beam, and improve the stability of the ion beam.

[0166] The ion guiding mechanism 4 includes a second electrode plate 41 and a second protruding ring 42 extending from the second electrode plate 41 toward the cluster channel 130. The second protruding ring 42 is arranged around the second cluster through hole 40.

[0167] When a negative voltage is applied to the ion guiding mechanism 4, a stronger electric field gradient is formed at the end of the second convex ring 42, enabling the ion guiding mechanism 4 to simultaneously perform the dual functions of extraction and pre-focusing. The second convex ring 42 protrudes towards the cluster channel 130, bringing it closer to the ionization region, which is beneficial for efficiently pulling out positive ions from the ionization region.

[0168] When energized, the second convex ring 42 forms a converging equipotential surface in the region of the second cluster through hole 40, which exerts a radial compression effect on the incoming ion beam, so that the ion beam is initially focused before entering the downstream transmission system, reducing the beam emissivity.

[0169] The surface of the second convex ring 42 away from the second cluster through-hole 40 is arc-shaped, meaning the outer surface of the second convex ring 42 is a smooth arc surface, rather than an edge or sharp corner. The arc-shaped surface minimizes sharp edges, making the electric field distribution on the surface of the second convex ring 42 more uniform, significantly reducing the local electric field strength, and improving the withstand voltage capability of the ion guiding mechanism 4, enabling it to operate stably under negative voltages up to -2000V without breakdown.

[0170] Furthermore, during ion extraction, some ions that deviate from the axis bombard the arc-shaped surface of the second convex ring 42 at an inclined angle (not perpendicular). Compared to planar or sharp-angled structures, inclined incidence can reduce secondary electron emission.

[0171] The first convex ring 32 protrudes outward from the ionization chamber, and the second convex ring 42 protrudes inward from the ionization chamber. The two work together to make the electric field lines in the ionization region have a smooth axial orientation from the inlet to the outlet, and the radial component is minimized, thus achieving efficient ion extraction.

[0172] The thickness of the second convex ring 42 in the first direction is smaller than the aperture of the second cluster through-hole 40. While effectively guiding the ion beam, the smaller thickness in the first direction allows the ions to leave rapidly.

[0173] In one embodiment, the second cluster passes through a hole 40 with a diameter of 14 mm to 20 mm, for example, 15 mm. The thickness of the second convex ring 42 in the second direction is 3 mm to 4 mm.

[0174] Furthermore, the central axes of the first cluster through-hole 30, the cluster channel 130, and the second cluster through-hole 40 are aligned to form a precise alignment axis running through the entire ionization device 100. Throughout the entire process of the neutral cluster beam entering the ionization chamber from the upstream source region, passing through the ionization region, and exiting the ionization chamber as an ion beam, it always propagates along the same geometric axis. This avoids beam scraping losses and trajectory deflections caused by channel misalignment, ensuring lossless transmission of the cluster beam and precise alignment with the electron beam ionization region.

[0175] The aperture of the first cluster through-hole 30 is less than or equal to the inner diameter of the cluster channel 130, and the aperture of the second cluster through-hole 40 is greater than or equal to the inner diameter of the cluster channel 130, thus constructing a gradually expanding beam channel from the inlet to the outlet to ensure the smooth transmission of the cluster beam.

[0176] The smaller first cluster focuses the cluster beam through the aperture 30, compressing the incoming neutral cluster beam at the inlet, increasing the beam density, and restricting the entry of stray gas molecules.

[0177] The larger second cluster through the aperture 40 reduces the risk of ion beam scraping at the exit end. After ions acquire a certain transverse velocity component in the ionization region, they may diverge radially during their transport to the exit end. The larger exit aperture ensures that these ions can still be effectively extracted, reducing ion loss at the exit end.

[0178] In one embodiment, the aperture of the first cluster through-hole 30 is 6 mm; the inner diameter of the cluster channel 130 is 10 mm; and the aperture of the second cluster through-hole 40 is 15 mm.

[0179] The ion guiding mechanism 4 is configured to provide a voltage from 0V to -2000V after being energized, which provides a negative potential compared to the repulsion electrode 3 and the channel constraint structure 13, forming an axial accelerating electric field with the positive potential of the ionization region. Positively charged ions generated after ionization are accelerated and drawn out from the ionization region under the action of this axial accelerating cell, passing through the second cluster through-hole 40 into the downstream ion transport system.

[0180] The wide voltage range of 0V to -2000V provides continuous adjustment capability from no acceleration to strong acceleration, allowing for flexible matching of ion extraction energy to meet the requirements of subsequent ion optics systems. This efficient extraction mechanism improves the transport efficiency of ions from the ionization chamber to downstream systems and reduces ion loss at the exit end.

[0181] By adjusting the voltage of the ion guiding mechanism 4, the divergence angle of the ion beam can be controlled, the current intensity can be precisely adjusted, and the beam trajectory can be accurately guided.

[0182] In a preferred embodiment, the ion guiding mechanism 4 includes at least three stages of extraction electrodes. These three stages of extraction electrodes are arranged sequentially along the beam direction of the ion beam to accelerate and focus the ion beam.

[0183] In this invention, each structure that requires power is powered by a power supply module or an external voltage, and the power supply signal (voltage or current) can be adjusted independently, which is highly flexible and has a wide range of applications.

[0184] The ionization structure of the present invention further includes a barrier structure 5, which is preferably made of an insulating material, such as ceramic. The barrier structure 5 is disposed between any two adjacent electrically connected structures to achieve at least one of electrical isolation and physical limitation.

[0185] The barrier structure 5 includes a first barrier structure 51 disposed between the ionization cavity 1 and the focusing electrode 232. Both the ionization cavity 1 and the focusing electrode 232 are provided with a first limiting groove 511 that cooperates with the first barrier structure 51. The first barrier structure 51 is located in the first limiting groove 511, thus achieving both electrical isolation and physical limiting.

[0186] The barrier structure 5 includes a second barrier structure 52 disposed between the anode 231 and the focusing electrode 232. Both the anode 231 and the focusing electrode 232 are provided with a second limiting groove 521 that cooperates with the second barrier structure 52. The second barrier structure 52 is located in the second limiting groove 521, thus achieving both electrical isolation and physical limiting.

[0187] The ionization device 100 of the present invention further includes a housing 6, which includes an annular outer cylinder 61, a first outer wall 62 disposed on the inlet side of the ionization chamber, and a second outer wall 63 disposed on the outlet side of the ionization chamber. The housing 6 encloses the other structures, providing protection and electrical isolation. The housing 6 is made of an insulating material, such as ceramic.

[0188] The first outer wall 62 has an inwardly protruding protrusion that connects to the ionization chamber 1 (e.g., the first wall 11). The first outer wall 62 is isolated from the electron emission assembly 2 by a third barrier structure 53. The third barrier structure 53 is disc-shaped and has a third limiting groove 531 that cooperates with the first barrier structure 51 and the second barrier structure 52. Both the first outer wall 62 and the third barrier structure 53 have through holes that communicate with the ionization chamber (e.g., the cluster channel 130).

[0189] The second outer wall 63 has an inwardly protruding protrusion that connects to the ionization chamber 1 (e.g., the second wall 12). The second outer wall 63 is isolated from the electron emission assembly 2 by a fourth barrier structure 54. The fourth barrier structure 54 is disc-shaped and has a fourth limiting groove 541 that cooperates with the first barrier structure 51 and the second barrier structure 52. The fourth barrier structure 54 also has a support leg 542 that supports the second outer wall 63. Both the second outer wall 63 and the fourth barrier structure 54 have through holes that communicate with the ionization chamber (e.g., the cluster channel 130).

[0190] The novel ionization structure of this invention, as tested, shows that the ionization efficiency is increased by more than 30% compared to the existing structure, the divergence of the ion beam is reduced by 25%, the energy dispersion is reduced from 15% to 2%, the energy consumption is reduced by 20%, and the stability of the ion beam is significantly improved, which can effectively improve the surface treatment effect of materials in GCIB equipment. The novel ionization structure of this invention, with the electron emission unit 21 and focusing unit 23 working together, can provide multiple electron beams, increasing the collision probability between the electron beam and the cluster beam and significantly improving ionization efficiency. The focusing unit 23 focuses the electron beam, while the ion guiding mechanism 4 precisely guides and constrains the ionized ion beam, effectively reducing ion beam divergence. Furthermore, the use of the repulsion electrode 3 for potential compensation significantly reduces the energy dispersion of the extracted ion beam, improving its stability and contributing to the uniformity of material surface treatment. The electron emission unit 21, electron beam control unit 22, and focusing unit 23 of this invention cooperate with each other to optimize the structural design of the electron emission assembly 2. By employing high-efficiency hot cathode 211 material and through reasonable voltage regulation, the energy consumption of the equipment is reduced while ensuring ionization effect, which aligns with the development trend of energy conservation and environmental protection.

[0191] Based on the structure of the ionization device 100, the power supply signals of each component are independently and flexibly adjustable, which can be adapted to gas cluster beam devices of different power and specifications. At the same time, it is easy to process and assemble, and facilitates the transformation and upgrading of existing equipment. In addition, the key components are made of materials with excellent high temperature resistance, wear resistance and electrical conductivity, and have undergone special coating treatment, which extends the service life of the equipment and reduces the cost of use. In summary, the ionization device 100 of the present invention, through the electron beam channel design of multiple sets of electron emission components and a channel constraint structure, combined with the potential compensation of the repulsion electrode and the precise control of the ion guiding mechanism, can significantly improve ionization efficiency, reduce ion beam energy dispersion and divergence, and reduce equipment energy consumption. The ionization device 100 effectively solves the technical problems existing in the prior art, such as severe electron beam divergence leading to low ionization efficiency, large energy dispersion and divergence of the ionized ion beam leading to poor stability, poor electron beam focusing effect leading to low energy utilization, and high energy consumption. It has significant technical advantages and practical value, and can be widely applied in GCIB equipment-related fields, showing good prospects for promotion.

[0192] The present invention also provides a gas cluster ion beam production apparatus, including any of the above-described ionization devices 100. Other structures of the gas cluster ion beam production apparatus will not be described in detail here.

[0193] The present invention also provides an ionization control method applicable to any of the ionization devices 100 described above, and any description of the ionization device 100 can be incorporated into the control method. This control method is also applicable to other ionization devices 100 with similar structures.

[0194] The ionization control method includes the following steps: applying an electrical signal to the electron emission unit 21 to generate a plurality of electron beams; applying an electrical signal to the electron beam control unit 22 to constrain the electron beams to be emitted in the direction of the cluster channel 130; applying an electrical signal to the focusing unit 23 to focus the electron beams, causing the plurality of electron beams to enter the cluster channel 130 through a plurality of electron beam channels 134 respectively, and causing the central axes of the plurality of electron beams to intersect on the central axis of the cluster channel 130.

[0195] The present invention independently adjusts the electrical signals applied to the electron emission unit 21, the electron beam control unit 22 and the focusing unit 23, which can generate an electron beam and constrain and focus it onto the central axis of the cluster channel 130. The high focusing degree can greatly improve the ionization efficiency.

[0196] In some embodiments, the electron emission unit 21 is a thermionic cathode 211, to which a heating current of 80A to 100A is provided to ensure stable electron emission. A floating voltage of -1000V to 0V is also provided to the thermionic cathode 211, cutting off the path between the thermionic cathode 211 and the ground where the equipment is located, minimizing interference introduced by the grounding loop, improving the signal-to-noise ratio of the emission current, and facilitating the acquisition of a pure electron beam. Ionization energy is precisely controlled through the heating current and the floating voltage. A larger voltage difference applied to the thermionic cathode 211 results in a larger current generated on the thermionic cathode 211, which can increase the electron emission density and enhance the ionization intensity.

[0197] In some implementations, a more negative electrical signal than that of the electron emission unit 21 is applied to the electron beam control unit 22 to form an electrostatic repulsion field, thereby confining the electron beam to the direction of the cluster channel 130.

[0198] In some embodiments, the focusing unit 23 includes an anode 231 and a focusing electrode 232 coaxially disposed inside the anode 231. The anode 231 is provided with a first electron passage hole 2311, and the focusing electrode 232 is provided with a second electron passage hole 2321 corresponding to the first electron passage hole 2311.

[0199] The control method also includes providing a voltage of 0V to 500V to the anode 231. An accelerating electric field is formed in the region of the first electron passage hole 2311. Electrons emitted by the hot cathode 211 gain kinetic energy under the action of the accelerating electric field and pass through the first electron passage hole 2311. The electron beam is radially constrained during the process of passing through the first electron passage hole 2311, thus achieving preliminary focusing.

[0200] The control method also includes providing a voltage of 0V to 2000V to the focusing electrode 232. The voltage of the focusing electrode 232 is higher than that of the anode 231, forming a stronger accelerating electric field inside the focusing electrode 232. The electron beam is subjected to stronger radial confinement as it passes through the focusing electrode 232, and the divergence angle is further compressed.

[0201] The ionization device 100 also includes a repulsion electrode 3 disposed at the entrance of the ionization chamber. A compensation voltage is applied to the repulsion electrode 3 to create an equipotential region within the ionization chamber, thereby ensuring that the central cluster beam enters the cluster channel 130 without disturbance at its original velocity and direction, and reducing ion energy dissipation.

[0202] The ionization device 100 also includes an ion guiding mechanism 4 disposed at the outlet of the ionization chamber. An electrical signal is applied to the ion guiding mechanism 4 to draw out the ion beam. It can also generate a radial compression effect on the ion beam so that the ion beam is initially focused before entering the downstream transmission system, thereby reducing the beam emissivity.

[0203] The following provides Example 1 and Comparative Example 1 to describe in detail the ionization device 100 of the present invention and its performance. The ionization device 100 includes an ionization chamber 1, an electron emission assembly 2, a repulsion electrode 3, an ion guiding mechanism 4, and a power supply module.

[0204] Example 1 The ionization chamber 1 is a cylindrical ionization chamber with an inner diameter of 50 mm and a length of 18 mm. The ionization chamber 1 includes a first wall 11, a second wall 12, and a channel constraint structure 13 located between the two.

[0205] The channel constraint structure 13 includes an annular column 131 that encloses and forms a cluster channel 130, and a plurality of drainage walls 132 extending outward from the outer surface of the annular column 131 facing away from the cluster channel 130. The region on the annular column 131 between adjacent drainage walls 132 has a third electron passage hole 133. The gap between adjacent drainage walls 132 and the third electron passage hole 133 together form an electron beam channel 134.

[0206] The cylindrical cluster channel 130 can avoid unnecessary collisions between ions and the cavity wall, reducing charge loss.

[0207] Six electron beam channels 134 are evenly distributed within the channel constraint structure 13. Each electron beam channel 134 has an inner diameter of 10 mm and a groove depth of 2 mm, with adjacent channels evenly distributed at 60° intervals. The design of the electron beam channels 134 guides and directs the electron beam, allowing it to enter the ionization cavity 1 simultaneously from six directions. This improves the electron beam's arrival efficiency within the ionization cavity 1 and increases the probability of collisions between electrons and the cluster beam. The even distribution of the six electron beam channels 134 enables omnidirectional coverage of the ionization region by the electron beam. The ionization chamber 1 is made of 316L stainless steel. 316L stainless steel has excellent electrical conductivity and corrosion resistance, making it suitable for processing corrosive gases. The inner wall of the ionization chamber is coated with an alumina insulating coating with a thickness of 0.5 mm. This alumina insulating coating improves electrical insulation performance and prevents leakage between the ionization chamber 1 and other electrodes.

[0208] The repulsion electrode 3 is a disc-shaped structure made of 316L stainless steel, with a through hole in the middle. The diameter of the through hole is 6mm and the depth is 7mm. The voltage applied to the repulsion electrode 3 matches the voltage of the main body of the ionization chamber 1, thereby creating an equipotential region or a weak accelerating electric field between the inlet of the ionization chamber 1 and the channel constraint structure 13 to suppress ion backflow and reduce extraction energy dissipation.

[0209] Specifically, when the cluster beam enters the ionization cavity 1, it is bombarded and ionized by electrons in the ionization region to form positive ions. The positive ions move towards the exit end under the action of the electric field. A positive voltage is applied to the repulsion electrode 3 (the same as or slightly higher than the main voltage of the ionization cavity 1, for example, within 1%), forming an equipotential region in the entrance region to prevent positive ions from flowing back towards the entrance. At the same time, a weak accelerating electric field is formed in the channel constraint structure 13 region, enabling the ions to gain initial kinetic energy and move along the axial direction, reducing collisions between ions and the cavity wall, reducing energy loss, and ultimately reducing the ion beam energy dispersion from 15% to 2%.

[0210] Several electron emission components 2 are symmetrically arranged around the ionization cavity 1. Each electron emission component 2 includes an electron emission unit 21, an electron beam control unit 22, and a focusing unit 23.

[0211] The electron emission unit 21 includes six emission sources and a fixing ring 212 for securing the six emission sources. The six emission sources are evenly distributed at 60° angles along the circumference of the ionization chamber, corresponding one-to-one with the six electron beam channels 134 on the inner wall of the ionization cavity 1, achieving precise electron beam guidance. The electron beams in six directions can cover the entire space of the ionization region, avoiding ionization dead zones. The emission sources are made of tungsten wire drawn (e.g., straightened), and fixed at both ends with bolts. Tungsten wire has the characteristics of long life, high temperature resistance, and high electron emission efficiency, which can ensure the long-term stability of electron emission. The diameter of the tungsten wire is 0.2mm to 0.5mm. If the diameter is too small, the tungsten wire will melt and break; if the diameter is too large, the heating will be insufficient and the electron emission efficiency will be reduced. The effective heating length of the tungsten wire is 15mm to 20mm.

[0212] The suppressor is a ring-shaped structure with a groove 221 opening towards the first electron passage hole 2311 of the anode 231. The hot cathode 211 is housed inside the suppressor. The suppressor is used to constrain the electron beam emitted by the hot cathode 211 to the direction of the anode 231 through electrostatic repulsion, thus constraining the emission direction of the electron beam and preventing it from diverging in other directions. The power supply module applies a negative voltage (relative to the hot cathode 211) to the suppressor, forming an electrostatic repulsion field inside the suppressor. Electrons emitted by the hot cathode 211 are constrained to the opening direction by the electrostatic repulsion and move only along the direction of the first electron passage hole 2311, preventing the electron beam from hitting the inner wall of the suppressor and causing energy loss.

[0213] The anode 231 and the focusing electrode 232 are coaxially nested, with the anode 231 located outside the focusing electrode 232. Both the anode 231 and the focusing electrode 232 are made of 316L stainless steel, which has good electrical conductivity and corrosion resistance, and can adapt to long-term working environments.

[0214] The anode 231 has a first electron passage hole 2311 with a diameter of 9 mm and a thickness of 6 mm. The function of the anode 231 is to allow the electron beam to pass uniformly through the first electron passage hole 2311 and to provide initial focusing. A positive voltage of 0V to 500V is applied to the anode 231, forming an accelerating electric field in the region of the first electron passage hole 2311. Electrons emitted from the thermionic cathode 211 gain kinetic energy under the action of the accelerating electric field and pass through the first electron passage hole 2311. The electron beam is radially constrained during its passage through the first electron passage hole 2311, achieving initial focusing. The thickness of the anode 231 is based on the required acceleration distance of the electron beam in the accelerating electric field.

[0215] The focusing electrode 232 is coaxially disposed inside the anode 231, with an inner diameter of 9 mm and a length of 5 mm. The focusing electrode 232 is used to further compress the electron beam divergence angle, concentrating the electron beam on the cluster beam region. A positive voltage of 0V to 2000V is applied to the focusing electrode 232, higher than the voltage of the anode 231, creating a stronger accelerating electric field inside the focusing electrode 232. As the electron beam passes through the focusing electrode 232, it experiences stronger radial constraint, further compressing the divergence angle.

[0216] An ion guiding mechanism 4 is located at the outlet end of the ionization chamber 1 and consists of at least one parallel and coaxially arranged guiding electrode plate. The surface of the guiding electrode plate has a second cluster passage hole 40 adapted to the ion beam trajectory, with a hole diameter of 15 mm. The guiding electrode plate is 3 mm thick and has a titanium nitride coating with a coating thickness of 0.3 mm. The function of the ion guiding mechanism 4 is to precisely guide and constrain the ion beam after ionization, reducing the divergence of the ion beam and improving its stability. A negative voltage of 0V to -2000V is applied to the guiding electrode plate, forming an electrostatic lens in the guiding electrode plate region. Under the action of the electrostatic lens, the ion beam is radially constrained, reducing its divergence.

[0217] The power supply module is electrically connected to the electron emission assembly 2, the repulsion electrode 3, and the ion guiding mechanism 4, respectively, providing heating current to the thermionic cathode 211 and adjustable DC voltage to the anode 231, the focusing electrode 232, and the guiding electrode plate. Specifically, the power supply module provides a heating current of 80A to 100A to the thermionic cathode 211 to achieve sufficient thermionic emission; the thermionic cathode 211 has an independently adjustable suspension voltage of -1000V to 0V, which allows the thermionic electrons to gain initial kinetic energy and sufficient ionization energy when colliding with the cluster beam. The power supply module provides a voltage of 0V to 500V to the anode 231 and a voltage of 0V to 2000V to the focusing electrode 232, forming a graded accelerating electric field that gradually focuses the electron beam during acceleration. The guiding electrode plate voltage of -2000V forms an electrostatic lens to radially constrain the ion beam.

[0218] The working principle of the ionization device 100 in this embodiment is as follows: The cluster beam enters the ionization chamber 1 from the inlet end of the ionization chamber 1 through the first cluster of the repulsion electrode 3 via the hole 30. The positive voltage applied by the repulsion electrode 3 forms an equipotential region in the inlet area, preventing ion backflow. Six sets of electron emission components 2 work simultaneously. The hot cathode 211 heats up to generate electrons, which are constrained to the direction of the ionization chamber by the electrostatic repulsion of the suppression electrode. The first electron of the anode 231 passes through the hole 2311 to initially focus the electron beam. The accelerating electric field of the focusing electrode 232 further accelerates and focuses the electron beam. The six electron beams enter the ionization chamber 1 simultaneously from six directions through the electron beam channel 134, colliding with the cluster beam and ionizing the cluster beam to form positive ions. The repulsion electrode 3 forms a weak accelerating electric field in the channel constraint structure 13 region, and the positive ions gain initial kinetic energy and move axially towards the outlet end. As the ion beam passes through the ion guiding mechanism 4, a voltage of -2000V-0 is applied to the guiding electrode to form an electrostatic lens, which radially constrains the ion beam and reduces its divergence. Finally, the ion beam is led out from the outlet of the ionization cavity 1 with low energy dispersion and low divergence.

[0219] Comparative Example 1 The only difference between the comparative example and the embodiment is that the repulsion electrode 3 is not voltage compensated.

[0220] Please refer to Figure 15 As shown in (b), after applying a compensation voltage to the repulsion electrode 3, an approximately identical potential field is constructed in the ionization chamber.

[0221] Please refer to Figure 16 As shown, the energy dissipation ratio before and after potential compensation is simulated by numerically solving the potential distribution in the ionization chamber and performing ion-by-ion tracking simulation. Figure 16 (a) shows the simulated values ​​without compensation, with an ion energy dissipation of 15 eV. Figure 16 Figure (b) shows the simulated values ​​under the applied compensation voltage to the repulsive electrode 3. The final ion energy dissipation value obtained after compensation potential is <3eV.

[0222] comprehensive Figure 15 and Figure 16 It can be seen that after applying a compensation voltage to the repulsion electrode 3, an approximately identical potential field is constructed in the ionization chamber, which greatly reduces the ion energy dissipation value.

[0223] Furthermore, to simplify the complexity of the ionization device 100, the ion guiding mechanism 4 typically uses a single or two-stage electrode, which leads to increased ion beam divergence, typically measured in ion beam divergence angles of 100 mrad. In this invention, the ion guiding mechanism 4 employs a three-electrode extraction structure. Please refer to... Figures 17 to 19 As shown, the ion beam divergence angle obtained by optimizing the electrode layout is 75 mrad, which is significantly better than the traditional two-electrode layout.

[0224] It should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0225] The detailed descriptions listed above are merely specific descriptions of feasible embodiments of the present invention, and are not intended to limit the scope of protection of the present invention. All equivalent embodiments or modifications made without departing from the spirit of the present invention should be included within the scope of protection of the present invention.

Claims

1. An ionization device, characterized in that, include: An ionization cavity includes an ionization chamber and a channel constraint structure located within the ionization chamber. The channel constraint structure has a cluster channel extending along a first direction and a plurality of electron beam channels intersecting and communicating with the cluster channel. The central axes of the plurality of electron beam channels intersect on the central axis of the cluster channel. A plurality of electron emission components are disposed around the ionization chamber and correspond one-to-one with the electron beam channels. Each electron emission component includes an electron emission unit, an electron beam control unit, and a focusing unit. The electron emission unit is configured to emit electrons after being powered on. The electron beam control unit is configured to constrain the electron beam to be emitted toward the cluster channel after being powered on. The focusing unit is located between the electron beam control unit and the ionization chamber. The focusing unit has an electron passage hole corresponding to the electron beam channel. After being powered on, the focusing unit causes the electron beam to enter the cluster channel through the electron passage hole and the electron beam channel, respectively. The channel constraint structure includes an annular column forming the cluster channel and a plurality of drainage walls extending outward from the outer surface of the annular column facing away from the cluster channel. The annular column has a third electron passage hole in the region between adjacent drainage walls. The gap between adjacent drainage walls and the third electron passage hole together constitute the electron beam channel. The electron beam channel extends radially along the cluster channel and penetrates the annular column.

2. The ionization device according to claim 1, characterized in that: The cluster channel is symmetrical about its central axis and has a smooth inner wall transition.

3. The ionization device according to claim 1, characterized in that: The number of electron beam channels is N, and the N electron beam channels are uniformly arranged along the circumferential direction of the cluster channels.

4. The ionization device according to claim 3, characterized in that: N is an even number, and the N electron beam channels are symmetrically arranged with respect to the central axis of the cluster channels.

5. The ionization device according to claim 1, characterized in that: The electron emission unit includes a hot cathode, at least a portion of which is disposed within the electron beam control unit, or at least a portion of which is disposed between the electron beam control unit and the focusing unit.

6. The ionization device according to claim 5, characterized in that: The electron beam control unit is a suppressor electrode, and the suppressor electrode at least partially surrounds the electron emission unit; Alternatively, the electron beam control unit includes a groove opening toward the focusing unit, and at least a portion of the hot cathode is disposed within the groove.

7. The ionization device according to claim 1, characterized in that: The focusing unit includes an anode and a focusing electrode coaxially disposed inside the anode. The electron passage includes a first electron passage disposed on the anode and a second electron passage disposed on the focusing electrode. The first electron passage and the second electron passage correspond to and are coaxially disposed with the electron beam channel.

8. The ionization device according to claim 7, characterized in that: The diameter of the first electron passage hole is not greater than the diameter of the second electron passage hole, and the diameter of the second electron passage hole is not greater than the inner diameter of the electron beam channel.

9. The ionization device according to claim 7, characterized in that: The anodes of several electron emission components together form a ring anode, and several first electrons are uniformly disposed on the ring anode through holes; The focusing electrodes of several electron emission components together form an annular focusing electrode, and several second electron passage holes are uniformly disposed on the annular focusing electrode. The annular focusing electrode is coaxially disposed inside the annular anode, and several first electron passage holes, several second electron passage holes and several electron beam channels correspond one-to-one and are coaxially disposed. The electron beam control units of several electron emission components together form an annular suppressor; the annular suppressor is coaxially disposed outside the anode, and the annular suppressor is located outside the first electron passage hole; The electron emission unit includes a thermionic cathode, and the thermionic cathodes of a plurality of electron emission components correspond one-to-one with the first electron passage hole.

10. The ionization device according to claim 9, characterized in that: The annular suppressor electrode has a groove recessed in the direction away from the ionization chamber and a through hole for the hot cathode to extend into the groove, the through hole being through in a first direction; The electron emission assembly further includes a pair of fixing rings respectively disposed on both sides of the annular suppressor in the first direction, the two ends of the hot cathode are respectively fixed on the two fixing rings, and the hot cathode passes through the through hole and through the groove.

11. The ionization device according to claim 9, characterized in that: A barrier structure is provided between the ionization cavity and any two adjacent electrically connected structures in the electron emission assembly to achieve at least one of electrical isolation and physical limitation.

12. The ionization device according to claim 1, characterized in that: The ionization device also includes a power supply module configured to provide the electron emission unit with a heating current of 80A to 100A and a floating voltage of -1000V to 0V.

13. The ionization device according to claim 1, characterized in that: The ionization device further includes a power supply module, and the focusing unit includes an annular anode and a focusing electrode coaxially disposed inside the anode. The power supply module is configured to provide a higher potential to the focusing electrode than to the anode.

14. The ionization device according to claim 13, characterized in that: The power supply module is configured to provide a voltage of 0V to 500V to the anode and a voltage of 0V to 2000V to the focusing electrode.

15. The ionization device according to claim 1, characterized in that: The ionization device further includes a repulsion electrode disposed at the inlet end of the ionization chamber. The repulsion electrode is insulated from the ionization cavity and has a first cluster passage hole that extends along a first direction and communicates with the cluster channel. The ionization device further includes a power supply module electrically connected to the repulsion electrode, the power supply module being configured to output an independently adjustable compensation voltage to the repulsion electrode to create an equipotential region in the ionization chamber.

16. The ionization device according to claim 1, characterized in that: The ionization device further includes an ion guiding mechanism disposed at the outlet end of the ionization chamber. The ion guiding mechanism has a second cluster passage hole that extends along a first direction and communicates with the cluster channel. The ion guiding mechanism is configured to provide a negative potential after being energized, so as to form an axial accelerating electric field between itself and the ionization chamber for drawing out positive ions. The negative potential is a voltage of 0V to -2000V.

17. The ionization device according to claim 1, characterized in that: The ionization device further includes a repulsion electrode, an ion guiding mechanism, and a power supply module electrically connected to both the repulsion electrode and the ion guiding mechanism; The repulsive electrode is disposed at the inlet end of the ionization chamber, and the repulsive electrode has a first cluster passage hole that extends along a first direction and communicates with the cluster channel; The ion guiding mechanism is disposed at the outlet end of the ionization chamber, and the ion guiding mechanism has a second cluster passage hole that extends along a first direction and communicates with the cluster channel; The central axes of the first cluster through-hole, the cluster channel, and the second cluster through-hole are aligned. The diameter of the first cluster through-hole is less than or equal to the inner diameter of the cluster channel, and the diameter of the second cluster through-hole is greater than or equal to the inner diameter of the cluster channel.

18. The ionization device according to claim 17, characterized in that: The repulsive electrode includes a first electrode plate and a first protruding ring extending from the first electrode plate toward the cluster channel, the first protruding ring being disposed around the first cluster through a hole; The ion guiding mechanism includes a second electrode plate and a second convex ring extending from the second electrode plate toward the cluster channel. The second convex ring is arranged around the second cluster through hole, and the surface of the second convex ring away from the second cluster through hole is arc-shaped.

19. A gas cluster ion beam production apparatus, characterized in that, Includes the ionization device according to any one of claims 1 to 18.

20. An ionization control method applied to the ionization device according to any one of claims 1 to 18, characterized in that, Includes the following steps: An electrical signal is applied to the electron emission unit to generate several electron beams; An electrical signal is applied to the electron beam control unit to constrain the electron beam to be emitted toward the cluster channel; An electrical signal is applied to the focusing unit to focus the electron beam, causing the electron beams to enter the cluster channel through the electron beam channels, and causing the central axes of the electron beams to intersect on the central axis of the cluster channel.

21. The ionization control method according to claim 20, characterized in that: The ionization device also includes a repulsion electrode disposed at the entrance of the ionization chamber; The ionization control method further includes: A compensation voltage is applied to the repulsion electrode to create an equipotential region within the ionization chamber.

22. The ionization control method according to claim 20, characterized in that: The electron emission unit is a hot cathode, to which a heating current of 80A to 100A and a floating voltage of -1000V to 0V are provided.

23. The ionization control method according to claim 20, characterized in that: A more negative electrical signal than that of the electron emission unit is applied to the electron beam control unit to form an electrostatic repulsion field, thereby confining the electron beam to the cluster channel.

24. The ionization control method according to claim 20, characterized in that: The focusing unit includes an anode and a focusing electrode coaxially disposed inside the anode. The anode has a first electron passage hole, and the focusing electrode has a second electron passage hole corresponding to the first electron passage hole. The control method includes: providing a voltage of 0V to 500V to the anode and a voltage of 0V to 2000V to the focusing electrode.

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