阅读说明：本技术 一种产生掺杂碱金属或卤素的耦合气体团簇离子束的装置和方法 (Device and method for generating coupled gas cluster ion beam doped with alkali metal or halogen ) 是由 亚历山大·托斯托古佐夫 付德君 吐沙姑·阿不都吾甫 瓦西里·帕里诺维奇 张翔宇 左文彬 于 2021-07-29 设计创作，主要内容包括：本发明设计了一种可产生掺杂性单电荷态碱金属正离子或卤素负离子的耦合气体团簇离子束的装置,并提出了用于产生该团簇离子束的方法。本发明旨在通过一个表面电离离子源所产生的低能单电荷态碱金属正离子或卤素负离子来掺杂产生耦合气体团簇离子束,以此提高装置的工作效率。在反应过程中用单原子离子代替分子离子或络合离子,避免了掺杂性离子在掺杂过程中的碎裂现象。本发明通过由大量气体原子(例如Ar)组成的中性气体团簇束流来捕获低能量的单电荷态碱金属正离子或卤素负离子,从而形成耦合气体团簇离子束。(The invention designs a device for generating a coupled gas cluster ion beam of doping single charge state alkali metal positive ions or halogen negative ions and provides a method for generating the cluster ion beam. The invention aims to generate coupled gas cluster ion beams by doping low-energy single-charge-state alkali metal positive ions or halogen negative ions generated by a surface ionization ion source so as to improve the working efficiency of the device. In the reaction process, the monoatomic ions are used for replacing molecular ions or complex ions, so that the fragmentation phenomenon of doping ions in the doping process is avoided. The present invention forms a coupled gas cluster ion beam by capturing low-energy singly-charged alkali metal positive ions or halogen negative ions through a neutral gas cluster beam composed of a large number of gas atoms (e.g., Ar).)

1. A method of generating an alkali metal or halogen doped coupled gas cluster ion beam, characterized by: the method comprises the following steps that neutral gas cluster beams formed by a gas power source enter an ionization chamber formed by an ion source, the ion source generates ion beams formed by single-charge alkali metal positive ions or halogen negative ions through surface ionization, the direction of the ion beams is perpendicular to the direction of the neutral gas cluster beams, and the neutral gas cluster beams capture the single-charge alkali metal positive ions or the single-charge halogen negative ions to form alkali metal or halogen-doped coupling gas cluster ion beams.

2. The method of generating an alkali metal or halogen doped coupled gas cluster ion beam of claim 1, wherein: neutral gas cluster beam is Ar_nThe size of the cluster is more than or equal to 500 and less than or equal to 5000, and the energy is within the range of 30-300 eV.

3. The method of generating an alkali metal or halogen doped coupled gas cluster ion beam of claim 1, wherein: the alkali metal positive ion is Cs⁺The halogen anion is Br^-Or I^-。

4. An apparatus for generating a coupled gas cluster ion beam doped with an alkali metal or halogen for use in the method of claim 1, wherein: at least comprises an ion source which is sequentially provided with a cathode ionizer, a working substance storage tank and a heater from inside to outside, wherein the cathode ionizer is made of porous tungsten or LaB pressed into porous graphite₆The working substance storage tank is heated by a heater to generate alkali metal positive ions or halogen negative ions.

5. The apparatus for generating an alkali metal or halogen doped coupled gas cluster ion beam as claimed in claim 4, wherein: the ion source is in a hollow cylinder shape, and the hollow part of the ion source forms an ionization chamber.

6. The apparatus for generating an alkali metal or halogen doped coupled gas cluster ion beam as claimed in claim 5, wherein: the ion source can be heated by a heater until working substances are melted, atoms generated by melting the working substances form alkali metal positive ions or halogen negative ions through a cathode ionizer, and the alkali metal positive ions or the halogen negative ions enter the ionization chamber to be coupled with the neutral gas clusters to form coupled gas cluster ions; the outlet of the ionization chamber is provided with an extraction electrode, and the coupled gas cluster ions are extracted by the extraction electrode to form coupled gas cluster ion beams which enter an ion transmission cylinder formed by a diaphragm, a mass separator, a focusing lens, a deflection electrode and the like.

7. The apparatus for generating an alkali metal or halogen doped coupled gas cluster ion beam as claimed in claim 5, wherein: the working substance stored in the working substance storage tank is CsI or CsBr.

8. The apparatus for generating an alkali metal or halogen doped coupled gas cluster ion beam as claimed in claim 5, wherein: the heater is a resistance heater, the resistance heater is electrically connected with a current stabilizing power supply, and the current stabilizing power supply supplies power to the resistance heater; the resistance heater and the current stabilizing power supply are connected with a stabilized voltage power supply which provides negative high voltage, and the stabilized voltage power supply provides kinetic energy for ions.

9. The apparatus for generating an alkali metal or halogen doped coupled gas cluster ion beam as claimed in claim 5, wherein: the ion source is arranged on a stainless steel carrier, namely a cathode ionizer, a working substance storage tank, a heater and the stainless steel carrier are sequentially arranged from inside to outside, and two ends of the ion source are sealed by graphite diaphragms.

10. The apparatus for generating an alkali metal or halogen doped coupled gas cluster ion beam as claimed in claim 6, wherein: permanent magnets are arranged in interaction areas of an inlet and an outlet of the ionization chamber, and the interaction areas are areas where alkali metal positive ions or halogen negative ions are coupled with neutral gas clusters.

Technical Field

The invention relates to a device and a method for generating coupled gas cluster ion beams doped with alkali metals or halogens, belonging to the fields of cluster ion sources and ion beams and ion beam micro-nano processing.

Background

The cluster consisting of 500-5000 atoms can be doped by compounding alkali metal positive ions or halogen negative ions in a single charge state, and the ion beam of the cluster doped in the way can carry out surface modification, ultrafine polishing and shallow layer injection on various materials (including insulators), and can also carry out layer-by-layer and local microscopic analysis on complex inorganic materials, biological materials and various organisms (including thin films) and be used for exciting chemical reactions on the surfaces of the complex inorganic materials, the biological materials and the organisms.

The state of the art and production processes are capable of producing HCl, H doped with chemically active molecules₂O and CH₄Coupled argon cluster ion beams. In these devices, gaseous or vaporous reactive dopants are injected into the coupling chamber of the ion source at a partial pressure of 1-5% relative to the argon pressure, where they are embedded in the Ar cluster structure, and the formed coupled clusters are then ionized by an electron beam in an ionizer. The fundamental disadvantage of this solution is that it is not possible to generate negatively charged cluster ions, which is necessary for dielectric material processing (e.g. polishing of glass) and for the analysis of low-conductive organic materials, since the negative charge of the primary ions compensates for the surface discharge of the material surface due to ion-electron emission. Technically, the design of the apparatus becomes more complicated due to the need to add a coupling chamber for introducing the reaction gas, evacuating and controlling the pressure.

The method and the device are known at present, and cations and anions extracted from the room-temperature ionic liquid are doped into clusters, so that coupled gas cluster ion beams with two polarities are formed. From a technical point of view, this device is a gas particle source of a neutral cluster beam of rare gas, behind the exit diaphragm of which a conical ion source with an axial slit is mounted. The ion source operates in a field evaporation mode to generate positive and negative ion beams of room temperature ionic liquid. In the chamber, a neutral cluster of rare gas interacts with the dopant ions and then forms a dopant doped with room temperature ionsRare gas cluster ion beams of cations or anions of the daughter liquid, i.e., coupled cluster ion beams with positive or negative charges. One disadvantage of this prototype is due to the adiabatic expansion (E) of the working gas from the nozzle_kin100eV) to form a neutral cluster beam having a significant difference in kinetic energy, and thus the coupled cluster ion beam generation efficiency is low for both polarities. Ions formed by field evaporation of cations or anions in room temperature liquids with sharp edges of a slit ion source (E)_kinNot less than 1500 eV). The retardation of these ions causes the ion beam to be defocused, reducing its density and reducing the probability of ions being captured by the neutral gas cluster beam. In addition, the cations and anions of the room temperature liquid are complex ions that may be decomposed when interacting with the neutral cluster beams.

Disclosure of Invention

The invention aims to design and manufacture a gas dynamic source capable of generating alkali metal positive ions or halogen negative ions doped with single charge state coupled cluster ion beams, because the energy of the doped ions is greatly reduced, the working efficiency is higher than that of the existing prototype, and the problem of decomposition does not exist when the monatomic ions are used for doping and interact with neutral cluster beams.

In order to solve the problem, the invention provides a method for generating a coupled gas cluster ion beam doped with alkali metal or halogen, a neutral gas cluster beam formed by a gas power source enters an ionization chamber formed by an ion source, the ion source generates an ion beam formed by alkali metal positive ions or halogen negative ions in a single charge state through surface ionization, the direction of the ion beam is perpendicular to the direction of the neutral gas cluster beam, and the neutral gas cluster beam captures the alkali metal positive ions or the halogen negative ions in a single charge state to form the coupled gas cluster ion beam doped with the alkali metal or the halogen.

And the neutral gas cluster beam is Ar_nThe size of the cluster is more than or equal to 500 and less than or equal to 5000, and the energy is within the range of 30-300 eV.

And the alkali metal positive ion is Cs⁺The halogen anion is Br^-Or I^-。

The device for generating the coupled gas cluster ion beam doped with the alkali metal or the halogen at least comprises an ion source, the ion source comprises a cathode ionizer, a working substance storage tank and a heater from inside to outside, and the cathode ionizer is made of porous tungsten or LaB pressed into porous graphite₆The working substance storage tank is heated by a heater to generate alkali metal positive ions or halogen negative ions.

Furthermore, the ion source is in the shape of a hollow cylinder, the hollow part of which forms an ionization chamber.

The ion source can be heated by a heater until working substances are melted, atoms generated by melting the working substances form alkali metal positive ions or halogen negative ions through a cathode ionizer, and the alkali metal positive ions or the halogen negative ions enter the ionization chamber to be coupled with the neutral gas clusters to form coupled gas cluster ions; the outlet of the ionization chamber is provided with an extraction electrode, and the coupled gas cluster ions are extracted by the extraction electrode to form coupled gas cluster ion beams which enter an ion transmission cylinder formed by a diaphragm, a mass separator, a focusing lens, a deflection electrode and the like.

And the working substance stored in the working substance storage tank is CsI or CsBr.

The heater is a resistance heater, the resistance heater is electrically connected with a current stabilizing power supply, and the current stabilizing power supply supplies power to the resistance heater; the resistance heater and the current stabilizing power supply are connected with a stabilized voltage power supply which provides negative high voltage, and the stabilized voltage power supply provides kinetic energy for ions.

The ion source is arranged on a stainless steel carrier, namely a cathode ionizer, a working substance storage tank, a resistance heater and the stainless steel carrier are sequentially arranged from inside to outside, and two ends of the ion source are sealed by graphite diaphragms.

And the interaction region of the inlet and the outlet of the ionization chamber is provided with a permanent magnet, and the interaction region is a region in which alkali metal positive ions or halogen negative ions are coupled with neutral gas clusters.

The technology successfully improves the performance and efficiency of the device by forming the coupled gas cluster ion beam by using low-energy alkali metal positive ions or halogen negative ions with single charge as doping ions, wherein the doping ions are generated by a hollow cylindrical ion source with surface ionization. This geometry provides a high density of dopant ions in the ionization chamber. In addition, monoatomic ions are used instead of molecular ions or complex ions, so that fragmentation of doped ions is eliminated, and the use performance of the ion beam is improved.

Drawings

Fig. 1 is a schematic view of an alkali metal positive ion or halogen negative ion coupled cluster ion beam generating apparatus doped with a single charge state. In the figure: the method comprises the following steps of 1-a gas power source, 2-neutral cluster beam, 3-a beam splitter, 4-a coupling chamber, 5-a cathode ionizer, 6-a working substance storage tank, 7-a resistance heater, 8-a current stabilizing power supply, 9-doped ions, 10-a voltage stabilizing power supply, 11-a grounding electrode, 12-a leading-out electrode, 13-electrons, 14-a permanent magnet and 15-a graphite membrane.

Fig. 2 is a schematic circuit diagram of a resistance heater and a regulated power supply connected to a regulated power supply providing a negative high voltage.

Detailed Description

As shown in FIG. 1, the gas power source 1 is provided with a high-pressure gas flow which can form a neutral cluster beam 2, such as Ar_nWherein n is more than or equal to 500 and less than or equal to 5000. The gas power source is formed by connecting a conical supersonic nozzle with a high-pressure (5-10bar) gas source. The nozzle made of metal has a bore diameter of 50 to 100 μm, a length of the spouting portion of 30mm, and a taper angle of 5 to 10 degrees. The neutral cluster beam 2 is guided by a beam splitter 3 into an ionization chamber 4 in which a positive alkali metal ion source (e.g., Cs) is installed⁺) Or a source of halide anions (e.g. Br)^-Or I^-). The ion source is hollow cylinder type and made of stainless steel as a carrier, the hollow part of the ion source forms an ionization chamber, and two ends of the ion source are sealed by graphite film sheets 15. The ion source comprises a cathode ionizer 5 made of porous tungsten (for generating positive ions) or LaB intercalated in porous graphite₆Powder (for generating negative ions). Below the cathode ionizer there is a reservoir 6 filled with a working substance (for example CsI or CsBr). The ion source is composed of a resistorThe heater wire or resistance heater 7 is heated and is powered by a current stabilizing power supply 8. That is, the whole structure of the hollow cylindrical ion source is sequentially provided with a cathode ionizer, a working substance storage tank, a resistance heater and a stainless steel carrier from inside to outside, the ionization chamber is not a structure which is independently arranged or additionally prepared, but the hollow part of the hollow cylindrical ion source can be directly used as the ionization chamber when in actual use, and the ion source shown in fig. 1 has a cross-sectional structure. The vapors of the working substance diffuse through the porous cathode ionizer to the surface where singly charged positive or negative ions 9 are formed according to different modes of operation (polarity on the cathode). The kinetic energy of the ions depends on the acceleration voltage and is controlled by regulated power supply 10. A zero-potential cylindrical electrode 11 (grounding electrode) is made of a tungsten grid with 90% transmittance, and the interaction area of doped ions (namely singly-charged alkali metal positive ions or halogen negative ions) and neutral inert gas beams is controlled. The doped ions in the region are coupled with clusters, and the formed coupled cluster ion beam is led out by an extraction electrode 12 and enters an ion transmission cylinder formed by a diaphragm, a mass separator, a focusing lens, a deflection electrode and the like.

Fig. 2 is a schematic diagram showing a specific circuit in which the resistance heater and the steady-current power supply are connected to a regulated power supply for supplying a negative high voltage, and the resistance heater and the steady-current power supply are connected to the regulated power supply for supplying the negative high voltage, so that the negative ions are accelerated to move toward the center of the ion source under the action of the negative high voltage. The energy of the ion depends on the value of the negative high voltage, so the kinetic energy of the ion is controlled by the stabilized voltage power supply.

In the negative ion generation mode, the cathode ionizer 5 also emits electrons 13. To prevent electrons from entering the interaction region of the inlet and outlet of the ionization chamber, permanent magnets 14 are mounted at these two locations, whose magnetic field causes significant deflection of the electrons, and which do not alter the trajectories of the dopant ions due to the large difference in mass of the electrons and ions.

The coupled cluster ions are formed by: neutral gas cluster beam (e.g., Ar) formed from a gas power source_n) Entering into an ionization chamber, wherein the size of the cluster is more than or equal to 500 and less than or equal to 5000, and the energy is within the range of 30-300 eV. The ion source is heated to 700 ℃ and 1200 ℃, at which temperature the working species occursMelting (the melting points of CsI and CsBr are 621 ℃ and 636 ℃ respectively), forming positive ions or negative ions by the emitted atoms through a cathode ionizer, and coupling the positive ions or the negative ions with the argon cluster in a coupling chamber to form coupled cluster ions.

To form positively charged alkali metal dopant ions, e.g. having a first ionization energy E_iDiffusion of cesium vapor at 3.9eV into work function through porous tungsten powderThe heated surface undergoes a surface ionization process. Degree of ionization alpha under thermal equilibrium conditions⁺I.e. the number of positive ions n in the same flow of evaporated material⁺With a neutral number of atoms n^oThe ratio of (c) can be described by the Saha-Langmuir formula under a first approximation:

wherein g is⁺、g^oStatistical weights for formed cation and initial atom (g for monovalent atom in thermodynamic equilibrium), respectively⁺＝1，g^o2). At T1000K, ionization degree alpha of cesium atoms on surface of tungsten cathode ionizer⁺About 500 a. Ionization coefficient beta of cesium atom⁺I.e. the fraction of cesium atoms that acquire a positive charge (lose electrons), can be described by the following formula:

to form negatively charged halogen dopant ions, e.g. with electron affinity S_aIodine vapor of 3.06eV is diffused to LaB of 2.66eV work function by a heated storage device₆The surface of a cathode ionizer. As in the case of generating alkali metal positive ions on the surface of the cathode ionizer, a surface ionization process of halogen atoms occurs. The first approximation of the degree of anion ionization can also be described by the Saha-Langmuir formula:

wherein g is^-、g^oStatistical weights for the anion formed and the initial atom (g for a monovalent atom in thermodynamic equilibrium), respectively^-＝1，g^o2). When T is 1000K, LaB₆Ionization degree alpha of iodine atoms on surface of cathode ionizer^-About 500 a. Ionization coefficient beta of iodine atom^-That is, the portion representing the total number of iodine atoms to which a negative charge (electron) is obtained, can be described by the following formula:

thus, in the manner described above, surface ionized atoms of alkali metals or halogens can provide a positive ionization coefficient and a negative ionization coefficient close to 1. In the negative ion generation mode, the cathode ionizer will also emit electrons in the apparatus shown in fig. 1, but the electrons cannot enter the ionization chamber due to the deflection of the magnetic field of the permanent magnet. Because of LaB₆Chemically active at high temperatures and can react with stainless steel components, thus isolating the cathode ionizer from the cylindrical stainless steel chamber through the graphite diaphragm.

Positive and negative doped ions accelerated in the space between the cathode ionizer and the grid, having an energy of up to 20keV or more, form chemically active positive or negative cluster ions when interacting with the cluster beam of the working gas. Beta due to ionization coefficient of dopant ions⁺And beta^-(see equations (2) and (4)) is independent of the acceleration voltage that occurs in the field evaporation case, so the operating efficiency of the apparatus of the present invention is higher than that of the prior art apparatus. The device can control the energy of the evaporated ions in a wider range so as to increase the capture section of the neutral gas cluster and reduce the possibility of cluster fragmentation when colliding with the doped ions. The hollow cylindrical structure of the ion source provides high density dopant ions in the ionization chamber, which also enhancesThe working efficiency of the equipment of the invention.