JPS60211751A - Ion beam generation device - Google Patents

Abstract

PURPOSE:To greatly improve the ionizing efficiency and the ion selectivity by a method, in which a material to be ionized is optically excited in resonance from its ground state to the Rydberg state by irradiation of the synchrotron radiation light, while further putting it into an ionized state from the excitation state by impressing an electric field. CONSTITUTION:Magnesium vapor 10 is introduced into a container 1 from a gas introduction hole 1a. The synchrotron radiation light B3 is introduced into the container 1 from the generation part 3 of the synchrotron radiation light, while the magnesium vapor 10 is resonantly excited from the ground state to the Rydberg state. The voltage is impressed on the electrodes 5 and 6 respectively synchronizing with the introduction of the synchrotron radiation light, while an electric field is impressed on the magnesium vapor 10 in the Rydberg state and the magnesium vapor 10 is ionized due to the Stark effect. Further, the direct current voltage is impressed between the electrodes 6 and the sample stand 8a while the ionized magnesium vapor 10 is pulled out as the ion beam 9 made up only of magnesium ions, and radiated on the sample 8.

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 the resonant light excitation and ionization method, in which the substance to be ionized is in a Rydberg-like state that can be ionized by the Stark effect as a state immediately before being ionized by resonant light excitation. @
By using (Rydberg 1level),
It is an object of the present invention 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 light excitation and ionization methods, 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 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, that is, the basal state! ! First, the magnesium atom in 3s ('S) is brought into the first excited state 3p by the laser beam B1 of 2853 people.
('PO), then resonantly excited to energy level 3d (ID) 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. Furthermore, in order to ionize the excited vapor, for example, by applying an electric field represented by the following equation to the vapor together with synchrotron radiation light, ionization is performed from this excited state by the Stark effect, which is also different from the conventional method. Different from ionization method.

E (V/am) =0.3125X10' ・n-4
Here, n is the effective principal quantum number of the Rydberg state.

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 (ID). Therefore, the output energy of synchrotron radiation is 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 the impurity atoms, only the substance to be ionized can be ionized. It is possible to produce highly pure products.

Furthermore, by changing the wavelength and electric field strength 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. You can leave it there. 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 and 6 are synchrotron radiation light generators that generate 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 electric field generating section 15 that applies an ionizing electric field for ionizing the substance in the container 1. 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. Note that the ionization electric field may also serve as the extraction electric field.

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, and then synchrotron radiation light B3 is introduced into the container 1 from the synchrotron radiation light generating section 3, whereby the magnesium vapor 10 is absorbed by the synchrotron radiation light. B3 causes resonance excitation from the ground state 33 (13) to the Rydberg state 29p (IPG).

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 (
An electric field is applied to the magnesium vapor 10 at 'P'), so that the magnesium vapor 10 is ionized due to the Stark effect. Further, a DC voltage is applied between the electrode 6 and the sample stage 8a, whereby the ionized magnesium vapor 10 is extracted as an ion beam 9 consisting only of magnesium 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 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 light and the applied voltage, 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. is open to allow the substance 12 to evaporate.

11 is a magnet that focuses the ionized magnesium vapor 10 on the axis of the container l, 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 apply an electric field to the vapor 10. As a result, the vapor 10 is excited from the ground state 3s (IS) to the Rydberg state 29p ('PO), and furthermore, due to the Stark effect, the electrons of the magnesium vapor 10 in the Rydberg state 29p (IPO) become free electrons, which causes the magnesium Ions are generated, and after the magnesium ions are focused on the axis by the magnet 11, they are emitted as an ion beam 9 by the extraction electrode 14.

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
24 is an electron storage ring, 24 is a spectroscopic system, and 33 is a container.

The synchrotron radiation introduced into the container 33 is first accelerated by the linear accelerator 21, and the electrons are accelerated into the electron storage ring 2.
Synchrotron radiation light is emitted from the electrons that have reached relativistic speed in the ring 22 and are further introduced into the spectroscopic system 24, where the spectroscopic system 24 converts the light into a single wavelength.

(Effects of the Invention) As described above, according to the ion beam generator according to 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 further the substance is Since the excited state is changed to an ion state by applying an electric field, 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. DESCRIPTION OF SYMBOLS 1... Container, 15... Electric field generation part, 20... Synchrotron radiation generation part, B3... Synchrotron radiation light. Note that the same reference numerals in the figures indicate the same or equivalent parts. Agent Masuo Oiwa Diagram 1 procedural amendment (voluntary) 1. Indication of the incident: Patent Application No. 1983-66900; 3. Name of the person making the amendment (601) Mitsubishi Electric Co., Ltd. Representative Katayuni 8th Department 4, Agent 5, Column for detailed explanation of the invention in the specification to be amended, and drawings (Figs. 1 and 2) , Fig. 4) 6. Contents of amendment +11 Change rlevel J on page 3, line 20 of the specification to [
Corrected to 5tate J. (2) On page 6, lines 3 and 4, "the energy level and wavelength of the synchrotron radiation are those of the impurity atoms" is corrected to "the wavelength of the synchrotron radiation is the energy level of the impurity atoms." (3) On page 9, lines 4-5, "The energy level and wavelength of the laser beam are related to those of the above impurities, etc." is corrected to "The wavelength of synchrotron radiation light is the energy level of impurity atoms." . (4) Figures 1, 2, and 4 are corrected as shown in the attached sheet. that's all

Claims (1)

[Claims] (11) A container containing a substance to be ionized, and an accelerator equipped with a wiggler or an undulator; a synchrotron radiation light generation section that resonantly optically excites the substance from the ground state to the Rydberg state; and an electric field generation section that applies an electric field to the substance in the container to change it from the Rydberg state to the ionic state due to the Stark effect. An ion beam generator characterized in that: (2) The synchrotron radiation light generating section generates channeling radiation light as synchrotron radiation light. (3) The ion beam generating device according to claim 1 or 2, characterized in that an electron storage ring or an electron synchrotron is used as the accelerator. (4) Claim 1, wherein the synchrotron radiation light generating section has a spectroscope or a spectroscopic system, and generates light of a single wavelength that is passed through the spectroscope or spectroscopic system. The ion beam generator according to any one of Items 1 to 3. (5) The synchrotron radiation generating section has a spectrometer or a spectroscopic system, and converts the substance from a ground state to an intermediate state to a Rydberg state. 2. The ion beam generating device according to claim 1, wherein the ion beam generating device generates a plurality of single wavelength synchrotron radiation beams that perform resonant light excitation in a stepped manner.