A low-energy neutral particle beam generator

Abstract

A low-energy neutral particle beam generating device belongs to the field of neutral particle beam technology. The ion beam is accelerated through an extraction device and enters an ion beam deflection device, where a diversion channel is provided, and a molecular pump is installed along the axial channel of the ion source. After passing through the deflection channel, the ion beam enters the ion beam analysis device and the neutralization device area, and passes through a charged particle stripping device. The present invention generates an ion beam based on an ion source, and collimates and regulates the energy of the ion beam through an ion beam extraction device; strips the neutral components in the beam through ion beam deflection and a molecular pump; neutralizes the ions based on surface grazing neutralization; and the neutralized beam passes through a charged particle stripping device to remove the charged components in the beam. The energy distribution and beam current density of the obtained neutral particle beam can be quantitatively measured through a neutral particle beam detection device, so as to be used for the calibration of neutral particle detectors and the study of the neutral beam etching process.

Description

Technical Field

[0001] The present invention belongs to the technical field of neutral particle beams, and in particular relates to a low-energy neutral particle beam generating device. Background Art

[0002] Low-energy neutral particle beams (LENB) generally refer to neutral particle beams with energies less than 100 eV. LENB technology has broad application prospects in a wide range of fields. For example, in aerospace, the detection and analysis of neutral particles in the space environment are essential for spacecraft attitude and orbit control and deep space exploration missions. These detection and analysis instruments require ground-based calibration before they can enter service. Considering the directional effects of spacecraft in the space environment, ground-based calibration research for space sensors using low-energy neutral particle beam technology can be conducted. Therefore, LENB technology is of great significance to the development of space neutral particle detection and analysis instruments. In semiconductor manufacturing, plasma etching is generally performed. However, this process accumulates charge on the substrate surface, leading to localized electric field distortion, which affects the directionality of the etching process and can even cause dielectric breakdown, reducing the reliability of integrated circuits. Furthermore, ultraviolet radiation emitted by plasma can create dangling bonds on the etched surface, which can have a detrimental impact on the performance of nanodevices. Consequently, numerous researchers are conducting research on neutral beam etching to address the issues of substrate damage and defects caused by plasma etching. Summary of the Invention

[0003] The purpose of the present invention is to provide a device for generating low-energy neutral particle beams, providing a device reference for ground calibration of space neutral gas measurement and analysis instruments and neutral beam etching research.

[0004] The technical solution adopted by the present invention is:

[0005] A low-energy neutral particle beam generating device comprises an air inlet, a discharge chamber, an ion extraction device, an ion beam deflection device, a molecular pump, an ion beam analysis device, a neutralization device, a charged particle stripping device, and a neutral particle beam detection device; the air inlet is provided at the front end of the discharge chamber, the ion extraction device is provided at the rear end outlet, the ion beam deflection device is provided at the outlet of the ion extraction device, a diversion channel is provided at the rear side of the ion beam deflection device, a molecular pump is installed on one channel, the ion beam analysis device and the neutralization device are provided in the other channel, and the charged particle stripping device is provided at the outlet of the other channel, and the neutral particle beam detection device is provided at the outlet of the charged particle stripping device.

[0006] Compared with the prior art, the present invention has the following beneficial effects:

[0007] The present invention generates an ion beam based on an ion source, and collimates and regulates the energy of the ion beam through an ion beam extraction device; strips off neutral components in the beam through ion beam deflection and a molecular pump; neutralizes ions based on surface grazing neutralization; and the neutralized beam passes through a charged particle stripping device to remove charged components in the beam.

[0008] The present invention utilizes a neutral particle beam detection device to quantitatively measure the energy distribution and beam current density of the obtained neutral particle beam. Compared to existing technologies, this device utilizes a single-aperture extraction method, achieving superior beam quality. It also integrates quantitative measurement of both ion and neutral beams, enabling in-situ comparative analysis of ion beams and neutralized particle beams. This provides a reference device for the calibration of neutral gas measurement and analysis instruments and for neutral beam etching. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a schematic structural diagram of the present invention;

[0010] Figure 2 It is a structural schematic diagram of the neutralization device of the present invention;

[0011] Figure 3 is a schematic diagram of the opening of the neutralization device of the present invention;

[0012] Figure 4 Schematic diagram of the structure of the ion extraction device of the present invention;

[0013] Figure 5 It is a schematic structural diagram of the charged particle stripping device of the present invention;

[0014] Among them: 1. Air inlet; 2. Discharge chamber; 2-1. Magnet coil; 2-2. Cathode; 2-3. Anode grid; 3. Ion extraction device; 3-1. Extraction electrode; 3-2-Accelerating electrode; 4. Beam deflection device; 5. Molecular pump; 6. Ion beam analysis device; 7. Neutralization device; 7-1. Suppression plate; 7-2. Neutralization plate; 8. Charged particle stripping device; 9. Neutral particle beam detection device; 9-1. Electron gun; 9-2. Flat-plate energy analysis device; 9-3. Microchannel plate; 9-4. Shielding shell. DETAILED DESCRIPTION

[0015] In order to better understand the purpose, structure and function of the present invention, the present invention is further described in detail below with reference to the accompanying drawings.

[0016] like Figure 1As shown, the present invention provides a low-energy neutral particle beam generating device, comprising an air inlet 1, a discharge chamber 2, an ion extraction device 3, an ion beam deflection device 4, a molecular pump 5, an ion beam analysis device 6, a neutralization device 7, a charged particle stripping device 8 and a neutral particle beam detection device 9; the air inlet 1 is provided at the front end of the discharge chamber 2, the ion extraction device 3 is provided at the rear end outlet, the ion beam deflection device 4 is provided at the outlet of the ion extraction device 3, a diversion channel is provided on the rear side of the ion beam deflection device 4, a molecular pump 5 is installed on one channel, an ion beam analysis device 6 and a neutralization device 7 are provided in the other channel, and a charged particle stripping device 8 is provided at the outlet of the other channel, and the neutral particle beam detection device 9 is provided at the outlet of the charged particle stripping device 8.

[0017] like Figure 1 As shown, the discharge chamber 2 is based on the principle of thermal emission electron bombardment ionization, and includes a magnetic coil 2-1, a cathode 2-2 and an anode 2-3; the cathode 2-2 is arranged inside the discharge chamber 2 near the air inlet 1, the anode 2-3 is installed inside the discharge chamber 2, and the magnetic coil 2-1 is installed outside the discharge chamber 2. The thermal electrons emitted by the cathode 2-2 collide with neutral atoms in the discharge area of ​​the discharge chamber 2 under the action of the electromagnetic field and ionize to generate plasma.

[0018] The discharge chamber 2 is grounded, and the anodes 2-3 are connected to an external adjustable high voltage source through ceramic insulation lead-out terminals.

[0019] Wherein: neutral atoms are provided into the discharge chamber 2 through the gas inlet 1 by the front gas supply device.

[0020] The electromagnetic field is provided by the magnet coil 2-1.

[0021] like Figure 1 、 Figure 4 As shown, the ion extraction device 3 has a single extraction aperture structure, comprising a coaxially arranged extraction electrode 3-1 and an accelerating electrode 3-2. The extraction diameters of the extraction and acceleration electrodes 3-1 and 3-2 are 20 mm. Ion extraction, focusing, and acceleration are achieved by applying positive and negative voltages of varying magnitudes to the extraction and acceleration electrodes 3-1 and 3-2, respectively.

[0022] like Figure 1 As shown, the ion beam deflection device 4 includes a pipe and a conductive coil wrapped around the pipe. The deflection magnetic field of the ion beam is primarily generated by the conductive coil wrapped around the pipe. By applying DC currents of varying magnitudes to the conductive coil, curved magnetic fields of varying strengths can be generated. This not only achieves deflected transmission of the charged ion beam but also reduces the full width at half maximum (FWHM) of the ion beam's energy distribution, resulting in a more monoenergetic ion beam.

[0023] The molecular pump 5 and the ion beam analysis device 6 are both existing technologies and purchased parts.

[0024] like Figure 1 、 Figure 2 As shown, the neutralization device 7 includes a suppression plate 7-1 and a neutralization plate 7-2. The suppression plate 7-1 and the neutralization plate 7-2 are two circular metal grids with coaxial holes and are both grounded. The suppression plate 7-1 is approximately 0.2 mm thick, and the neutralization plate 7-2 is approximately 2 mm thick. The suppression plate 7-1 and the neutralization plate 7-2 have coaxial holes with a diameter of approximately 200 μm. The holes are distributed in an equilateral triangle, and the distance between the hole centers is approximately 300 μm.

[0025] like Figure 3 As shown, the holes on the two circular metal grids are distributed in the shape of an equilateral triangle.

[0026] like Figure 1 As shown, the neutralization device 7 and the ion beam analysis device 6 are adjusted in radial position through a transmission mechanism, and the transmission mechanism is a linear transmission mechanism and is sealed by a bellows.

[0027] The linear transmission mechanism can adopt any existing mechanism capable of achieving reciprocating linear motion, such as a cylinder, a telescopic rod, a lead screw, etc., and the portion of the linear transmission mechanism extending into the channel is sealed by a bellows.

[0028] The charged particle stripping device 8 primarily consists of two semicircular electrodes, one above the other, connected by an insulator to form a cylindrical structure. One electrode, the positive electrode 8-1, is connected to a positive high voltage, while the other, the negative electrode 8-2, is connected to a negative high voltage. A deflection electric field is generated within the cylindrical structure, deflecting charged particles in the beam onto the electrodes for further absorption. A schematic diagram of its structure is shown in Figure 5.

[0029] like Figure 1 As shown, the neutral particle beam detection device 9 includes an electron gun 9-1, a flat-panel energy analyzer 9-2, a microchannel plate 9-3, and a shielding housing 9-4. The two electron guns 9-1 are symmetrically placed between the charged particle stripping device 8 and the flat-panel energy analyzer 9-2. The flat-panel energy analyzer 9-2 includes an upper metal plate and a lower metal plate, the distance between the upper and lower metal plates being L, which is 22.8 mm. The upper metal plate is maintained at ground potential, and a scanning positive voltage is applied to the lower metal plate. The upper metal plate has an entrance slit and an exit slit. The microchannel plate 9-3 is mounted at the exit slit. The entrance and exit slits have a diameter Δx of 2 mm and a distance x of 50 mm. The angle between the flat-panel energy analyzer 9-2 and the particle beam is θ, which is 45°. A shielding housing 9-4 is provided outside the microchannel plate 9-3.

[0030] The method of using the neutral particle beam detection device 9 is as follows:

[0031] Ions travel along a parabolic trajectory through the entrance slit of the flat-plate energy analyzer 9-2. The distance between the exit slit and the entrance slit is x. Depending on the initial ion kinetic energy and the voltage applied between the upper and lower metal plates, different horizontal distances are covered, achieving an energy selection effect. Ions with different energies ejected from the exit slit enter the microchannel plate 9-3, and corresponding current magnitudes can be obtained, thereby obtaining the energy distribution of the ions. The kinetic energy E of the ions ejected from the exit slit is related to the potential difference V between the plates:

[0032]

[0033] Where θ is the angle between the ion beam and the metal plate, and L is the distance between the upper and lower metal plates. The ion dispersion reaches its maximum value when θ = 45°, at which point formula (1) becomes:

[0034]

[0035] The above equation establishes a linear relationship between the potential difference between the plates and the ion energy at the exit slit. The resolution of the flat plate energy analyzer is:

[0036]

[0037] Here, Δx is the width of the slit.

[0038] Its working principle is as follows.

[0039] The working fluid gas enters the discharge chamber 2 through the air inlet 1 and is ionized into a plasma. A positive voltage is applied to the extraction electrode 3-1, forming an ion emission surface at the outlet. The ions are extracted and accelerated to the required energy level under the action of the acceleration voltage 3-2, forming an ion beam. After the ion beam enters the ion beam deflection device 4, the ions in the beam are deflected by the deflection magnetic field, and the neutral components in the beam are pumped away by the molecular pump 5. The neutralization device 7 and the ion beam analyzer 6 are adjusted in radial position through a transmission mechanism. During actual experiments, the ion beam analyzer 6 can perform in-situ measurements of characteristic parameters of the ion beam at the neutralization point, such as the divergence angle, energy distribution, and flux density. After measuring the characteristic parameters of the ion beam, the ion beam analyzer 6 exits the beam position through the transmission mechanism, and then transmits the neutralization device 7 to the beam position to neutralize the ion beam.

[0040] The ion beam passes through the neutralization device 7 for glancing neutralization. It then enters the charged particle stripping device 8, where the unneutralized ions are deflected by the deflection electric field and hit the charged electrode plate, where they are absorbed. This results in a neutral particle beam at the exit. The characteristic parameters of the generated low-energy neutral particle beam can be quantitatively analyzed using the neutral particle beam detection device 9.

[0041] Neutral particle beam detection device 9 measures the beam density and energy distribution of the neutral particle beam. Its operating principle is as follows. After exiting charged particle stripping device 8, neutral particles are ionized by high-energy electrons emitted by symmetrically positioned electron guns 9-1. They then enter the flat-panel energy analysis device 9-2. The path of charged particles in the electric field depends on their energy. A uniform, varying electric field is generated by applying a variable voltage V between two parallel metal plates.

[0042] Ions travel along a parabolic trajectory through the entrance slit of the flat-plate energy analyzer 9-2. The distance between the exit slit and the entrance slit is x. Depending on the initial ion kinetic energy and the voltage applied between the upper and lower metal plates, different horizontal distances are covered, which plays an energy selection effect. Ions with different energies ejected from the exit slit enter the microchannel plate (9-3), and the corresponding current size can be obtained, thereby obtaining the energy distribution of the ions. The kinetic energy E of the ions ejected from the exit slit is related to the potential difference V between the plates:

[0043]

[0044] Where θ is the angle between the ion beam and the metal plate, and L is the distance between the upper and lower metal plates. The ion dispersion reaches its maximum value when θ = 45°, at which point formula (1) becomes:

[0045]

[0046] The above equation establishes a linear relationship between the potential difference between the plates and the ion energy at the exit slit. The resolution of the flat plate energy analyzer is:

[0047]

[0048] Here, Δx is the width of the slit.

[0049] It will be understood that the present invention is described by way of some embodiments, and it will be appreciated by those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are intended to be protected by the present invention.

Claims

1. A low-energy neutral particle beam generator, characterized in that: The invention comprises an air inlet (1), a discharge chamber (2), an ion extraction device (3), an ion beam deflection device (4), a molecular pump (5), an ion beam analysis device (6), a neutralization device (7), a charged particle stripping device (8) and a neutral particle beam detection device (9); the air inlet (1) is arranged at the front end of the discharge chamber (2), the ion extraction device (3) is arranged at the rear end outlet, the ion beam deflection device (4) is arranged at the outlet of the ion extraction device (3), a diversion channel is arranged at the rear side of the ion beam deflection device (4), one of the channels is equipped with a molecular pump (5), the other channel is equipped with an ion beam analysis device (6) and a neutralization device (7), and the charged particle stripping device (8) is arranged at the outlet of the other channel, and the neutral particle beam detection device (9) is arranged at the outlet of the charged particle stripping device (8). The neutralization device (7) and the ion beam analysis device (6) are arranged at the mouth of the device, and radial position adjustment is achieved through a transmission mechanism, wherein the transmission mechanism is a linear transmission mechanism and is sealed by a bellows. The neutral particle beam detection device (9) comprises an electron gun (9-1), a flat plate energy analysis device (9-2), a microchannel plate (9-3) and a shielding shell (9-4); the two electron guns (9-1) are symmetrically placed between the charged particle stripping device (8) and the flat plate energy analysis device (9-2), the flat plate energy analysis device (9-2) comprises an upper metal plate and a lower metal plate, the upper metal plate is maintained at ground potential, and a scanning positive voltage is applied to the lower metal plate, an inlet slit and an outlet slit are formed on the upper metal plate, the microchannel plate (9-3) is installed at the outlet slit, and a shielding shell (9-4) is provided outside the microchannel plate (9-3).

2. The low-energy neutral particle beam generator according to claim 1, characterized in that: The discharge chamber (2) comprises a magnetic coil (2-1), a cathode (2-2) and an anode (2-3); the cathode (2-2) is arranged inside the discharge chamber (2) near the air inlet (1), the anode (2-3) is installed inside the discharge chamber (2), and the magnetic coil (2-1) is installed outside the discharge chamber (2); and the thermal electrons emitted by the cathode (2-2) collide with neutral atoms in the discharge area of ​​the discharge chamber (2) under the action of an electromagnetic field to generate plasma.

3. The low-energy neutral particle beam generator according to claim 1, characterized in that: The ion extraction device (3) is a single extraction hole structure, comprising a coaxially arranged extraction electrode (3-1) and an acceleration electrode (3-2), and by applying positive voltages and negative voltages of different magnitudes to the extraction electrode (3-1) and the acceleration electrode (3-2), ion extraction, focusing and acceleration effects are achieved.

4. The low-energy neutral particle beam generator according to claim 1, characterized in that: The ion beam deflection device (4) comprises a pipe and a conductive coil wrapped around the pipe.

5. The low-energy neutral particle beam generator according to claim 1, characterized in that: The neutralization device (7) comprises a suppression plate (7-1) and a neutralization plate (7-2); the suppression plate (7-1) and the neutralization plate (7-2) are two circular metal grids, the two circular metal grids have coaxial openings and are both grounded.

6. The low-energy neutral particle beam generator according to claim 5, characterized in that: The holes on the two circular metal grids are distributed in the shape of an equilateral triangle.

7. The low-energy neutral particle beam generator according to claim 1, characterized in that: The charged particle stripping device (8) is composed of two upper and lower semicircular electrodes, which are connected by insulation to form a cylindrical structure. One electrode is a positive electrode (8-1) connected to a positive high voltage, and the other electrode is a negative electrode (8-2) connected to a negative high voltage. A deflection electric field is constructed inside the cylindrical structure, so that the charged particles in the beam are deflected and hit the electrodes and are further absorbed.

8. The low-energy neutral particle beam generator according to claim 1, characterized in that: The ions pass through the entrance slit of the flat plate energy analysis device (9-2) and travel along a parabolic trajectory. The distance between the exit slit and the entrance slit is x. Different horizontal distances are covered according to the initial ion kinetic energy and the voltage applied between the upper metal plate and the lower metal plate, thereby achieving an energy selection effect. Ions with different energies ejected from the exit slit enter the microchannel plate (9-3), obtaining corresponding current magnitudes, thereby obtaining the energy distribution of the ions. The kinetic energy E of the ions ejected from the exit slit is related to the potential difference V between the plates: Where θ is the angle between the ion beam and the metal plate, and L is the distance between the upper and lower metal plates. The ion dispersion reaches its maximum value when θ = 45°, at which point formula (1) becomes: The above equation establishes a linear relationship between the potential difference between the plates and the ion energy at the exit slit. The resolution of the flat plate energy analyzer is: Here, Δx is the width of the slit.

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