Gas cluster ion beam ionization source based on electron focusing optical structure

Abstract

The present application relates to the technical field of gas cluster ion beam, and specifically discloses a gas cluster ion beam ionization source based on an electron focusing optical structure, which is used for generating a high-intensity gas cluster ion beam flow and comprises a hot cathode, a repeller, a focusing electrode and an electron accelerating electrode; the hot cathode is arranged at a predetermined position of the repeller and used for emitting an electron flow; the repeller, the focusing electrode and the electron accelerating electrode are arranged at predetermined positions and jointly constitute an electron beam focusing optical structure; the present application effectively solves the main problems existing in traditional gas ion sources through an innovative design, provides more stable and efficient gas cluster ion beam output, and has important significance for promoting the development of advanced processes, future technologies and other related fields of atomic-level manufacturing and processing.

Description

Technical Field

[0001] This invention belongs to the field of gas cluster ion beam technology, specifically relating to a gas cluster ion beam ionization source based on an electron focusing optical structure. Background Technology

[0002] Gas Cluster Ion Beam (GCIB) technology, as an advanced surface treatment method, has been widely used in materials processing, ion implantation, surface modification, and surface analysis. GCIB technology accelerates multiple atomic or molecular clusters into an ion beam, providing lower damage and higher precision during surface treatment. Therefore, GCIB technology can accurately remove surface layers without introducing excessive heat load, and is widely used in polishing and cleaning surface treatment processes for semiconductor materials, optical thin films, metals, and polymers. Gas cluster ion beam technology provides a new process approach to solve some problems in current advanced processes and integrated circuit manufacturing. This technology uses a high-pressure nozzle to supersonically expand inert or reactive gases and rapidly cool them in a vacuum, forming neutral clusters composed of tens to tens of thousands of atoms. These clusters are then ionized and accelerated in a vacuum by an ionization source to form a multi-atom cluster ion beam. In existing GCIB generation equipment, the ionization region of the beam is a key component, directly affecting the generation efficiency and transmission of the cluster ion beam. Conventional gas ion beam ionization regions employ a set of opposing thermionic electron guns. This approach often results in insufficient electron extraction efficiency and spatial dispersion of the electron beam, necessitating a longer gas flight space. This leads to a complex ionization chamber structure and uneven ion beam energy distribution due to electric field dispersion. Furthermore, the flight time of the ionization region also contributes to gas dispersion, affecting the vacuum level and thermal concentration of the ion transport environment. This is detrimental to the generation and transport of gas clusters, significantly limiting the development of current gas cluster ion beam technology and equipment. Summary of the Invention

[0003] The purpose of this invention is to provide a gas cluster ion beam ionization source based on an electron-focusing optical structure to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: A gas cluster ion beam ionization source based on an electron-focusing optical structure includes: Thermite cathode, reverse electrode, focusing electrode, electron accelerating electrode, and ionization region; The hot cathode, focusing electrode, and electron accelerating electrode are all provided in multiple sets and are arranged in a circular array with the ionization region as the center. The hot cathode is disposed at a predetermined position inside the reverse electrode and is used to emit an electron stream; The reverse electrode, focusing electrode, and electron accelerating electrode together constitute the focusing optical structure of the electron beam. The focusing optical structure is configured to focus the electron flow emitted by the hot cathode into an electron beam after a voltage is applied, forming a focusing path of the electron beam, and introducing electrons into the ionization region along this focusing path. The ionization region is an equipotential region, in which the energy of electrons is determined by the voltage difference between the electron accelerating electrode and the hot cathode; The focused electron beam collides with the gas cluster in a direction perpendicular to the gas cluster beam, causing it to ionize; The electron accelerating electrode is provided with a through hole for the gas cluster beam to pass through, and the overall structure of the hot cathode, the reverse electrode, the focusing electrode and the electron accelerating electrode is arranged around the path of the gas cluster beam to form a focused electron beam of equal energy in multiple directions.

[0005] Preferably, the focusing electrode is disposed inside the thrust electrode via an insulating support one, and the electron accelerating electrode is disposed on one side of the focusing electrode via an insulating support two.

[0006] Preferably, the distance between the hot cathode and the reverse electrode is 8 mm.

[0007] Preferably, the inner side of the reverse electrode is provided with multiple sets of grooves with an angle of 120°, and the hot cathode is located on the bottom side of the corresponding groove.

[0008] Preferably, the vertical distance between the focusing electrode and the hot cathode is 12 mm.

[0009] Preferably, the hot cathode is made of tungsten wire with an operating temperature above 600°C and a diameter ranging from 0.2 to 4.0 mm. In order to emit hot electrons from the cathode, its voltage is -3V.

[0010] Preferably, the materials of the reverse electrode, focusing electrode, and electron accelerating electrode are all conductive, preferably stainless steel. The working voltage is generally negative for the reverse electrode and positive for the focusing electrode and electron accelerating electrode. When the voltage combination is -35V, 10V, or 200V, the center energy of the focused electron beam is 203eV.

[0011] Preferably, the aperture of the through hole on the electron accelerating electrode is adjustable, ranging from 15mm to 35mm.

[0012] Preferably, the ionization source includes multiple hot cathode structures, which are repeatedly arranged around the gas cluster beam path.

[0013] Compared with the prior art, the beneficial effects of the present invention are: (1) Focused electron flow transport: An optical structure design of a focusing electrode is added between the traditional reverse electrode and the accelerating electrode. By guiding electrons to focus into the ionization region, the density of the electron flow is increased while the spatial distribution of ions in the ionization source is reduced. This is advantageous in the process of cluster ion generation because the distribution of heavier cluster particles in the gas ultrasonic beam is relatively narrow. This invention achieves a targeted improvement in the ionization region. (2) Improved ionization region structure: An optimized ionization chamber structure is provided, which surrounds the incident gas flow and does not obstruct the flight and transmission of the gas. The electron flow is introduced vertically into the ionization region, which enables the gas cluster particles to be converted into ion groups more effectively. The energy distribution of the ion beam is ensured to be more uniform by precisely controlling the acceleration voltage and current density, thereby improving the ionization efficiency while ensuring the spatial and energy distribution of the ion beam. (3) Electron output structure of hot cathode: During the electron generation process of hot cathode, the structure of the reverse electrode ensures that the surrounding distance of hot cathode is far and there will be no high heat concentration. For example, the predetermined distance between hot cathode and reverse electrode is 8mm, and the structural angle of reverse electrode is 120°. The introduction of a focusing structure allows hot electrons to enter the ionization region in the form of a focused beam after generation. The vertical distance between the focusing electrode and hot cathode is 12mm. (4) Ionization energy control: Ionization energy is the energy carried by electrons when colliding with gas clusters. It is determined by the voltage difference between the reverse electrode and the electron cathode. In the embodiments of this application, the range of electron energy can reach and exceed 900eV, which fully meets the needs of various practical applications. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the overall structure of the present invention; In the diagram: 1. Hot cathode; 2. Reverse electrode; 3. Focusing electrode; 4. Electron accelerating electrode; 5. Ionization region; 6. Focusing path; 7. Insulating support one; 8. Insulating support two. Detailed Implementation

[0015] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] Example: Please see Figure 1 As shown: This invention provides a gas cluster ion beam ionization source based on an electron-focusing optical structure, relating to the generation of cluster ion beams, including the following steps: 1. When the operating temperature is reached by applying pressure to the hot cathode 1, hot electrons will be released. At this time, the electron energy is relatively low. 2. Apply a negative voltage to the reverse electrode 2. At this time, a gradient electric field pointing towards the center of the ionization region 5 is formed around the hot cathode 1, causing electrons to flow towards the ionization center. 3. Apply a positive voltage to the focusing electrode 3. Its function is to increase the potential on both sides of the gradient field generated by the reverse electrode 2. At this time, the path of the electron beam is narrowed. 4. Finally, a suitable positive voltage is applied to the electron accelerating electrode 4 to achieve the final electron energy; 5. After passing through the focusing electrode 3, the electron beam enters the ionization region 5 and ionizes the ultrasonic gas beam from the gas beam source cavity in a focused beam state.

[0017] The present invention adopts an enclosed fabrication structure. The through hole of the electron accelerating electrode 4 is in the direction of gas flow, which avoids the loss of real electron flow caused by the general anode grid structure. With the above technical solution, five hot cathode structures are shown in the embodiment, which greatly improves the ionization efficiency and avoids the concentration of residual gas and thermal radiation.

[0018] When an appropriate voltage is applied, the electron beam emitted from the hot cathode 1 in this focusing optical structure forms a focused beam that enters the gas cluster beam region. After being charged, the ionization region becomes an equipotential region, and the electron energy is determined by the voltage difference between the electron accelerating electrode 4 and the cathode. The focused electron beam collides with the cluster in a manner perpendicular to the gas beam and ionizes it. The structure of the focused electron beam is repeatedly arranged around the gas beam, forming multiple electron beams with equal energy in multiple directions, which increases the electron density and thus improves the ionization efficiency. At the same time, it also reduces the spatial distribution of the ionization region, which is conducive to forming a concentrated cluster ion beam. This invention can confine the ionization region to a relatively small space, resulting in a significantly higher ionization efficiency, which is an order of magnitude higher than that of a typical opposed anode design.

[0019] In summary, this invention provides a novel gas cluster ion beam ionization source, which serves as a key component of gas cluster ion beam generation equipment, as described above. Figure 1 It includes a hot cathode 1 for electron generation and a reverse electrode 2, as well as a focusing electrode 3 and an electron accelerating electrode 4. The electron path during operation is shown as an electron beam focusing path 6.

[0020] The hot cathode 1 generates electrons and the reverse electrode 2. The relative position of the hot cathode 1 is about 8mm from the bottom of the 120° groove of the reverse electrode 2. The diameter of the hot cathode tungsten wire is within 8mm and can be replaced. The electron flow focusing lens is used to narrow the electron flow transmission path. Its position relative to the electron flow center is 12mm, and it is supported by an insulating bracket 7.

[0021] The aperture of the electron accelerating electrode 4 in the airflow path is adjustable from 15mm to 35mm and is supported by an insulating bracket 2 8.

[0022] The gas cluster ion beam ionization source based on electron focusing optical structure has a simple structure: the structure within the grid is discarded in the electron flight path, and the gas flow direction will not be blocked or the remaining gas will not accumulate. This effectively improves the utilization rate of hot electrons while avoiding gas accumulation in the ionization space.

[0023] The intensity of the focused electron beam is determined by the operating power of the hot cathode 1, and its energy is determined by the electron accelerating electrode 4.

[0024] This invention, through its innovative design, effectively solves the main problems of traditional gas ion sources, providing a more stable and efficient gas cluster ion beam output, which is of great significance for promoting the development of related fields such as atomic-level manufacturing and processing.

[0025] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A gas cluster ion beam ionization source based on an electron-focusing optical structure, characterized in that, include: Thermionic cathode (1), reverse electrode (2), focusing electrode (3), electron accelerating electrode (4), and ionization region (5); The hot cathode (1), focusing electrode (3), and electron accelerating electrode (4) are all provided in multiple sets and are arranged in a circular array with the ionization region (5) as the center; The hot cathode (1) is disposed at a predetermined position inside the reverse electrode (2) for emitting an electron stream; The reverse electrode (2), the focusing electrode (3) and the electron accelerating electrode (4) together constitute the focusing optical structure of the electron beam. The focusing optical structure is configured to focus the electron flow emitted by the hot cathode (1) into an electron beam after a voltage is applied, forming a focusing path (6) of the electron beam, and introducing electrons into the ionization region (5) along this focusing path (6). The ionization region (5) is an equipotential region, in which the energy of electrons is determined by the voltage difference between the electron accelerating electrode (4) and the hot cathode (1); The focused electron beam collides with the gas cluster in a direction perpendicular to the gas cluster beam, causing it to ionize; The electron accelerating electrode (4) is provided with a through hole for the gas cluster beam to pass through, and the overall structure of the hot cathode (1), the reverse electrode (2), the focusing electrode (3) and the electron accelerating electrode (4) is arranged around the path of the gas cluster beam to form a focused electron beam with equal energy in multiple directions.

2. The gas cluster ion beam ionization source based on an electron-focusing optical structure according to claim 1, characterized in that: The focusing electrode (3) is disposed inside the thrust electrode (2) by an insulating support one (7), and the electron accelerating electrode (4) is disposed on one side of the focusing electrode (3) by an insulating support two (8).

3. The gas cluster ion beam ionization source based on an electron-focusing optical structure according to claim 1, characterized in that: The distance between the hot cathode (1) and the reverse electrode (2) is 8 mm.

4. The gas cluster ion beam ionization source based on an electron-focusing optical structure according to claim 1, characterized in that: The inner side of the reverse electrode (2) is provided with multiple sets of grooves with an angle of 120°, and the hot cathode (1) is located on the bottom side of the corresponding groove.

5. A gas cluster ion beam ionization source based on an electron-focusing optical structure according to claim 1, characterized in that: The vertical distance between the focusing electrode (3) and the hot cathode (1) is 12 mm.

6. The gas cluster ion beam ionization source based on an electron-focusing optical structure according to claim 1, characterized in that: The hot cathode (1) is made of tungsten wire with a diameter ranging from 0.2 to 4.0 mm.

7. A gas cluster ion beam ionization source based on an electron-focusing optical structure according to claim 1, characterized in that: The reverse electrode (2), focusing electrode (3) and electron accelerating electrode (4) are all made of conductive materials.

8. A gas cluster ion beam ionization source based on an electron-focusing optical structure according to claim 1, characterized in that: The aperture of the through hole on the electron accelerating electrode (4) is adjustable, ranging from 15mm to 35mm.

9. A gas cluster ion beam ionization source based on an electron-focusing optical structure according to claim 1, characterized in that: The ionization source includes multiple hot cathode (1) structures, which are repeatedly arranged around the gas cluster beam path.

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