JPS60235344A - Ion beam generating apparatus - Google Patents

Abstract

PURPOSE:To steeply improve ionization efficiency and ion selectivity by exciting a substance to be ionized by resonant light excitation to automatic electrolytic dissociation condition from the basic condition through irradiation of light emitted from synchrotron. CONSTITUTION:The aluminum vapor 10 is supplied to a vessel 1 from a gas supply port 1a in order to oscillate a synchrotron emission light generating part 3. The synchrotron emission light B3 is guided to the vessel 1 through a slit 11. Thereby the aluminum vapor 10 is resonant-excited to the automatic electrolytic dissociation condition from the basic condition. As a result, excited vapor is ionized with a predetermined transition probability. A DC voltage is applied between an electrode 6 and a sample plate 8a and thereby the aluminum vapor 10 is extracted as the ion beam 9 consisting of only the ion 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 laser light and irradiate it onto a gas or liquid. to create plasma and use it as an ion source.
One is to use a variable wavelength light source to resonate a single wavelength of light or the like with the energy level of the substance to be ionized, and the present invention relates to the latter. , which uses synchrotron radiation rather than laser light as a light source.

[Summary of the invention]

The present invention provides an ion beam generation apparatus using resonant light excitation and ionization, in which an autoionization level of a substance is set as a state immediately before the substance is ionized by resonant light excitation.
), the purpose is to provide an ion beam generator that can improve the ionization efficiency for input light energy by several orders of magnitude compared to the conventional resonant light excitation ionization method and has excellent selectivity in selective ionization.

[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 an aluminum ion beam. FIG. 1 is an energy level diagram of aluminum neutral atoms.

Conventional ionization methods, for example, have a wavelength of 3082.

This is a method of irradiating the aluminum vapor to be ionized with two laser beams Bl and B2 of 6,200 people. In other words, aluminum atoms in the ground state 3p (2PO) are first transformed into the first excited state 3 by the laser beam B1 of 3,082 people.
d (2D) and then ionized by the laser beam B2 of 6200 people.

The ionization method used in the apparatus of the present invention differs from the conventional ionization method described above in that the final excited state is an auto-ionization state and that synchrotron radiation, particularly relativistic synchrotron radiation, is used as the excitation light source. It is in. Synchrotron radiation light has directionality like laser light,
In addition, it is a photon with much greater intensity and energy than a laser beam, and therefore, as shown in Figure 1, a single photon can excite aluminum vapor from the ground state to an auto-ionization state.
The excited vapor is ionized by autoionization with a predetermined transition probability.

In the case of the ionization method in the device of this invention, the collision cross section for ionization is several orders of magnitude higher than that in the conventional ionization method, which directly ionizes from energy level 3d (2D) or the like. Therefore, only a small output energy is required that does not cause multiple optical excitation or non-resonant photoionization of other particles, and since only resonance is used, the energy level of synchrotron radiation light is low.

If the wavelength is selected so that it does not match that of the impurity atoms, only the desired substance can be ionized, and the substance can be highly purified.

Furthermore, by changing the wave i 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. It's okay to stay. The method of the present invention, which allows the type of ion beam generated to be easily changed, is something that conventional methods do not have.
There is an advantage that two or more steps of processing with an ion beam can be performed in succession.

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 an evacuation bag W (not shown) for evacuating the container 1, and 3 is an accelerator equipped with a wiggler or an undulator. A synchrotron radiation light generating section that generates B3, 11 is a slit provided between the generating section 3 and the container 1, 6 is an electrode, and 6a is a terminal for applying voltage to the electrode 6. 8 is a sample, and 8a is a sample stand that holds the sample 8. A direct current voltage is applied between the sample stand 8a and the electrode 6, and a drawer is used to extract the ionized substance as an ion beam. An electric field is generated.

And this extraction electric field is the synchrotron radiation B
It has a phase that is temporally synchronized with 3.

Next, the operation will be explained.

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

Then, the synchrotron radiation light generating section 3 is caused to oscillate. Then, synchrotron radiation B3 with a wavelength of 1,762 people is introduced into the container 1 through the 2PO
) to the autoionization state 3s3p2 (2pO), and as a result, the excited vapor becomes an ionic state with a predetermined transition probability.

Further, a DC voltage is applied between the electrode 6 and the sample stage 8a, whereby the ionized aluminum vapor 10 is extracted as an ion beam 9 consisting only of aluminum ions. The sample 8 is irradiated.

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 aluminum, such as oxygen, nitrogen, carbon, hydrogen, etc., and the amount is greater than that of aluminum, the energy level and wavelength of synchrotron radiation light should not match those of the above impurities, etc. and the desired element, in this case aluminum,
A pure aluminum ion beam with only ionized aluminum is obtained.

Second, as mentioned above, this embodiment performs selective ionization, and ionization is performed by resonant optical excitation, which means that electrons and other elements are excited and the temperature rises 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.

-Thirdly, if you want to change the type or characteristics of the ion beam, you can simply change the wavelength of the synchrotron radiation light, and there is no need to open and close the container to take out the sample or replace the ion source, as in the past. 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 in FIG. 2 indicate the same or equivalent parts, 13 is a container containing the substance 12 to be ionized, 13a is a heater provided on the outer periphery of the container 13, serves as an oven in which the substance 12 is evaporated. 11 is ionized aluminum vapor 10
14 is an extraction electrode that extracts the focused aluminum vapor 10 as an ion beam 9.

Next, the operation will be explained.

Aluminum 1 which is a substance to be ionized in the container 13
When the aluminum 12 is heated in the oven 13 by the heater 13a, the aluminum 12 is melted.

It is vaporized and aluminum vapor 10 is generated. Then, the synchrotron radiation B3 is introduced into the container 13 through the throat 11 and irradiated onto the steam 10. As a result, the steam 10 changes from the ground state to the auto-ionization state 3S.
3p2 (2PO), and as a result, the excited vapor is automatically ionized with a predetermined transition probability to generate aluminum ions. After the aluminum ions are focused to the axis by the magnet 15, the ion beams are It is released as M9.

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
23 is an electron storage ring, 23 is a wiggler, and -24 is a spectroscopic system, which allows the synchrotron radiation generator 2
o is configured.

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 are shot into the electron storage ring 22, and synchrotron radiation is emitted from the electrons that have reached a relative speed in the ring 22. is,
Furthermore, the synchrotron radiation is introduced into the spectroscopic system 24, and the spectroscopic system 24
This is light that has been cut into a single wavelength. In this embodiment, since the wiggler 23 is provided, the range of wavelength tunability can be expanded in addition to the wavelength tunability '1 of the spectroscopic system 24.
It can generate an ion beam of seed material.

〔Effect of the invention〕

In this way, the ion beam generator according to the present invention resonantly optically excites a substance to be ionized from its ground state to an autoionized state by irradiation with synchrotron radiation light, and the excited vapor has a predetermined transition probability. Since it is automatically ionized into an 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 aluminum neutral atoms, FIG. 2 is a schematic configuration diagram of a sinker-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 the second embodiment, and FIG. 4 is a schematic diagram of a synchrotron radiation generator used in the present invention. 1.13.33...Yong! , 9... Ion beam, 2
0... Synchrotron radiation generation unit, 21... Accelerator, 23... Wiggler, B3... Synchrotron radiation light. Note that the same reference numerals in the figures indicate the same or equivalent parts. Agent Masuo Oiwa 1st Design (CML)

Claims (7)

[Claims] (1) An apparatus for generating an ion beam of the substance, comprising a container containing a substance to be ionized and a synchrotron radiation light generating section for irradiating the substance in the container with synchrotron radiation light, The synchrotron radiation light generating section is constructed by providing a wiggler or an undulator in an accelerator, and generates synchrotron radiation light having a wavelength that resonantly excites the above-mentioned substance from the ground state of the energy level to the auto-ionization state. An ion beam generator characterized by: (2) The ion beam generator according to claim 1, wherein the synchrotron radiation light generating section generates channeling radiation light as synchrotron radiation light. (3) The synchrotron radiation light generating section generates synchrotron radiation light having a plurality of line spectra with different wavelengths so as to resonantly excite the substance stepwise from the ground state to the autoionization state through the intermediate state. An ion beam generator according to claim 1 or 2, characterized in that the ion beam generator is an ion beam generator. (4) The synchrotron radiation light generating section has an accelerator and a spectrometer or a spectroscopic system, and generates light having a narrow line spectrum by passing the output from the accelerator through the spectrometer or spectroscopic system. An ion beam generator according to any one of claims 1 to 3, characterized in that the ion beam generator is an ion beam generator. (5) The ion beam generator according to any one of claims 1 to 4, characterized in that one or both of an electron storage ring, an electron cyclotron, and a ron are used as the accelerator. . (6) The synchrotron radiation light generating section generates synchrotron radiation light having a phase temporally synchronized with the phase of the ion beam extraction electric field. The ion beam source device according to any one of Item 5. (7) The substance described in any one of claims 1 to 6 is characterized in that the substance is introduced into the container as a vapor generated by heating and vaporizing a solid or liquid substance. Ion beam generator.