JPS60235348A - Ion beam generating apparatus - Google Patents

Abstract

PURPOSE:To steeply improve ionization efficiency and ion selectivity by exciting a substance to be ionized to the Rydberg condition from the basic condition through irradiation of the light emitted from the synchrotron and to ion condition by gas discharge. CONSTITUTION:The magnesium vapor 10 is supplied to a vessel 1 from a gas supply port 1a. The light emitted from the synchrotron B3 is guided to the vessel 1 from a synchrotron light generating part 3 and thereby the magnesium vapor 10 is resonant-excited to the Rydberg condition from the basic condition. A voltage is applied to electrodes 5 and 6 in synchronization with supply of the light emitted from the synchrotron and the magnesium vapor 10 under the Rydberg condition is ionized by the Stark effect due to the RF discharge. Moreover, a DC voltage is applied between the electrode 6 and a sample plate 8a and the sample 8 is irradiated with the ion beam 9.

Description

[Detailed description of the invention] [Technical field of invention] The present invention is applicable to material modification including semiconductor processing equipment.

This relates to ion beam generators used for materials synthesis, etc.

[Prior art]

Conventionally, various methods have been considered and put into practical use as ion generation methods using ion beam generators. Most of them used electric discharge, but in recent years ion sources using laser light have been devised. There are two methods of using light such as laser light: one is to irradiate a solid such as a metal with light and use the resulting plasma as an ion source, and the other is to focus the light and irradiate it onto a gas or liquid. to create plasma,
This is used as an ion source, and the other method uses a variable wavelength light source to ionize the substance by making a single wavelength of light resonate with the energy level of the substance to be ionized. The present invention relates to the latter, and particularly to one that uses synchrotron radiation rather than laser light as the light.

[Summary of the invention]

The present invention provides an ion beam generator using resonant light excitation and ionization as described above, in which the substance to be ionized is set in the Rydberg state (R
The purpose of this project is to provide an ion beam generator that can improve the ionization efficiency for input light energy by several orders of magnitude compared to conventional resonant optical excitation and ionization methods, and has excellent selectivity in selective ionization. There is.

[Embodiments of the invention]

First, the ionization method in the apparatus of the present invention will be explained by comparing it with a conventional method, taking as an example the case of generating a magnesium ion beam. FIG. 1 is an energy level diagram of a neutral magnesium atom.

In the conventional ionization method, for example, the wavelength is 2853.

This is a method of irradiating the magnesium vapor to be ionized with two laser beams Bl and B2 of 5,528 people. In other words, the magnesium atoms in the ground state 3s (IS) are first ionized into 2
The first excited state 3p (
'P'), then resonantly excited to energy level 3d (I D) by the laser beam B2 of 5528 people, and further ionized by the laser beam B1 of 2853 people.

The ionization method in the device of the present invention differs from the conventional ionization method described above in that the final excited state is the Rydberg state, and synchrotron radiation is used as the excitation light source.
In particular, it uses relativistic synchrotron radiation. Synchrotron synchrotron radiation has directionality like laser light, and is a photon with much greater intensity and energy than laser light. Therefore, as shown in Figure 1, a single photon can bring magnesium vapor out of the ground state. Can be excited to a highly excited state. Further, in order to ionize the excited vapor, glow discharge or radio frequency (RF) discharge is used, and ionization is performed from this excited state by the Stark effect, which is also different from conventional ionization methods.

In the case of the ionization method in this inventive device, compared to the conventional ionization method which directly ionizes from energy level 3d (ID), since only resonance is used, the collision cross section for ionization is several orders of magnitude higher. Therefore, the output energy of synchrotron radiation to excite atoms can be small, and since only resonance is used, if the energy level and wavelength of the synchrotron radiation are selected so as not to match those of impurity atoms, ionization can be achieved. It is possible to ionize only the substance you want to ionize, and it can also be of high purity.

In addition, by changing the wavelength of the synchrotron radiation light, ion beams of other types of substances can be easily generated.In this case, various types of substances to be ionized can be introduced into the ion beam generation container in advance. Also good. The method of the present invention, which allows the type of ion beam generated to be easily changed, is different from conventional methods, and has the advantage of being able to perform two or more processing steps using an ion beam in succession. be.

Next, embodiments of the invention will be described with reference to the drawings.

FIG. 2 shows a first embodiment of the invention. In the figure, 1
1a is a container into which the substance to be ionized is introduced; 1a is a gas introduction hole for introducing the substance into the container 1; 1b is a gas introduction hole for introducing the substance into the container 1;
3 is an exhaust passage connected to a vacuum evacuation device (not shown) for evacuating the container 1; 3 is an accelerator equipped with a wiggler or an undulator; 5.6 is the synchrotron radiation light generating section that generates the synchrotron radiation B
The electrodes 5a and 6a arranged across the electrode 5.3 are the electrodes 5a and 6a.
These are terminals for applying a voltage to 6, and these constitute an RF discharging live part 15 that generates an RF discharge for ionizing the substance in the container 1. 8 is the sample, 8
A is a sample stand that holds the sample 8, and a DC voltage is applied between the sample stand 8a and the electrode 6, thereby generating an extraction electric field for extracting the ionized substance as an ion beam. be done.

Next, the operation will be explained.

Let us consider the case where a magnesium ion beam is generated by the apparatus of this embodiment. First, magnesium vapor 10 is introduced into the container 1 through the gas introduction hole 1a.

Then, synchrotron radiation light B3 is introduced into the container 1 from the synchrotron radiation light generating section 3, and the magnesium vapor 10 is thereby changed from the ground state 3s ('S) to the Rydberg state 29p ( '
PO) is resonantly excited.

In addition, a voltage is applied to each of the electrodes 5 and 6 from the terminals 5a and 6a in temporal synchronization with the introduction of the synchrotron radiation, thereby causing the Rydberg state 29p (
The magnesium vapor 10 present at 'PO) is ionized by the Stark effect caused by the RF discharge. In addition, the electrode 6
A DC voltage is applied between the sample stage 8a and the ionized magnesium vapor 10, and the ionized magnesium vapor 10 is extracted as an ion beam 9 consisting only of magnesium ions, and the ion beam 9 irradiates the sample 8. be done.

The characteristics of this embodiment in the above operation description are as follows: First of all, since this embodiment performs selective ionization completely using only resonance, the substance to be ionized in the container 1, in this case, Even if it contains impurities other than magnesium, such as oxygen, nitrogen, carbon, hydrogen, etc., and even if the amount is greater than magnesium, the energy level of the laser beam will change.

A pure magnesium ion beam in which only the desired element, in this case magnesium, is ionized can be obtained by making the wavelength not coincident with those of the above-mentioned impurities.

Second, as mentioned above, this embodiment performs selective ionization and ionization by resonant optical excitation, so there is no possibility that electrons or other elements will be excited or that the temperature will rise due to energy absorption. As a result, low-temperature processing can be performed without increasing the temperature of the target sample 8 to be irradiated with the ion beam, such as a substrate in the case of a semiconductor.

Third, if you want to change the type or characteristics of the ion beam, you can simply change the wavelength of the synchrotron radiation and the discharge conditions, and you can remove the sample or open and close the container to replace the ion source, as in the case of conventional methods. This is not necessary, and therefore, continuous operations such as ion implantation and annealing can be easily performed.

FIG. 3 shows a second embodiment of the invention. In the figure, the same reference numerals as those in FIG. serves as an oven in which the substance 12 is evaporated.

11 is a magnet that focuses the ionized magnesium vapor 10 on the axis of the container 1, and 14 is an extraction electrode that extracts the focused magnesium vapor 10 as an ion beam 9.

Next, the operation will be explained.

Magnesium 1 which is a substance to be ionized in the container 13
When the container 13 is heated by the heater 13a, the magnesium 12 is melted and vaporized, and magnesium vapor 10 is generated. Then, synchrotron radiation B3 with a wavelength of 1625 people is introduced into the container 1, and the vapor 10 is
At the same time, a voltage is applied to the electrode 5.6 to generate an RF discharge. As a result, the steam 10 changes from the ground state 33 (1s) to the Rydberg state 29p ('P
O), and magnesium ions are generated by the Stark effect, and the magnesium ions are focused on the axis by the magnet 11 and then transferred to the extraction electrode 14.
The ion beam 9 is emitted as an ion beam 9.

FIG. 4 shows an example of the configuration of a synchrotron radiation generator used in the present invention. In the figure, 21 is a linear accelerator, 22
2 is an electron storage ring, and 24 is a spectroscopic system, which constitute a synchrotron radiation generator 20.

33 is a container to which synchrotron radiation light from the generator 20 is irradiated.

In the synchrotron radiation introduced into the container 33, electrons are first accelerated by the linear accelerator 21 and shot into the electron storage ring 22, and synchrotron radiation is emitted from the electrons that have reached relativistic speed in the ring 22. is,
Further, the emitted light is introduced into a spectroscopic system 24 and converted into a single wavelength by the spectroscopic system 24. In this embodiment, since the wiggler 23 is provided, the wavelength tunability range can be expanded in addition to the wavelength tunability of the spectroscopic system 24, and ion beams of various materials can be generated.

〔Effect of the invention〕

As described above, according to the ion beam generator of the present invention, the substance to be ionized is resonantly excited from its ground state to the Rydberg state by irradiation with synchrotron radiation light, and the substance is further excited by gas discharge. Since the state is changed from the state to the ion state, the ionization efficiency and ion selectivity can be greatly improved.

[Brief explanation of drawings]

FIG. 1 is an energy phase diagram of a singlet system of magnesium neutral atoms, FIG. 2 is a schematic diagram of the shower type ion beam generator according to the first embodiment of the present invention, and FIG. FIG. 4 is a schematic diagram of a focused ion beam generator according to an embodiment of the present invention, and FIG. 4 is a schematic diagram of a synchrotron radiation generator used in the present invention. , 1, 13.33... Container, 15... Gas discharge generating section, 20... Synchrotron radiation generating section, 21...
- Accelerator, 22... Electron storage ring, 24... Spectroscopic system, B3... Synchrotron radiation light. Note that the same reference numerals in the figures indicate the same or equivalent parts. Agent Masuo Oiwa Procedural Amendment (Voluntary) 59.10 9 Showa Year, Month, Day 2, Title of invention: Ion beam generator 3, Name of person making the amendment: (601) Mitsubishi Electric Corporation Representative Jinhachi Katayama 5, Column 6 of Detailed Description of the Invention in the Specification Subject to Amendment, Contents of the Amendment (1) "Stark effect" in the first line of page 5 of the specification is corrected to "electron collision, etc. due to high-frequency discharge." (2) "Stark effect" on page 6, line 13, page 9, line 8, and page 11, line 19 is corrected to "electron collision, etc."that's all

Claims (9)

[Claims] (1) A container containing a substance to be ionized, a synchrotron radiation generating section that irradiates the substance in the container with synchrotron radiation light, and a synchrotron radiation light generating unit that irradiates the substance in the container with synchrotron radiation light. and a gas discharge generating section that generates intersecting gas discharges, and in the apparatus for generating an ion beam of the substance, the synchrotron radiation light generating section resonantly optically excites the substance from the ground state of the energy level to the Rydberg state. 1. An ion beam generating device for generating synchrotron radiation having a wavelength such that the ion beam generating device generates synchrotron radiation light having a wavelength such that the ion beam generating device generates synchrotron radiation light having a wavelength such that the ion beam generating device changes the substance from a Rydberg state to an ion state by gas discharge. (2) The synchrotron radiation generating section generates a plurality of synchrotron radiation beams having different wavelengths so as to resonantly excite the substance stepwise from the ground state to the Rydberg state via the intermediate state. An ion beam generator according to claim 1, characterized in that: (3) The synchrotron radiation light generating section is characterized by having an accelerator and a spectroscope or spectroscopic system, and generating light having a narrow line spectrum after passing through the spectroscope or spectroscopic system. An ion beam generator according to claim 1 or 2. (4) The ion beam generating device according to claim 3, wherein either or both of an electron storage ring and an electron synchrotron are used as the accelerator. (5) The ion beam generator according to any one of claims 1 to 4, wherein the gas discharge generating section generates a high-frequency discharge. (6) The substance is introduced into the container as a compound or molecular gas, and the gas discharge also serves as a gas discharge to bring the substance introduced into the container into a neutral atomic state. An ion beam generator according to any one of claims 1 to 5. (7) The gas discharge generating section has a high frequency power source that resonates so that the substance changes from its Rydberg state to an ion state.
The ion beam generator described in Section 1. (8) The ion beam generator according to any one of claims 1 to 7, wherein the synchrotron radiation light and the gas discharge are temporally synchronized in phase. (9) The substance according to any one of claims 1 to 8 is introduced into the container as a vapor generated by heating and vaporizing a solid or liquid substance. Ion beam generator.