JPS60208039A - Ion beam generator - Google Patents

Abstract

PURPOSE:To improve the ionization efficiency by irradiating light emitted from a synchrotron light emitting section onto material to be ionized thereby performing resonance light excitation of said material from the bottom energy state to Rydber condition. CONSTITUTION:Magnesium vapor 10 to be ionized is led into a container 1 while electrodes 5, 6 are provided to lead a light beam B3 of 1,625Angstrom emitted from a synchrotron light emitting section 3 between said electrodes 5, 6. Said beam B3 will resonance excite the vapor 10 from the bottom state to Rydberg condition while voltage is applied between saie electrodes 5, 6 synchronously in time to ionize the vapor 10 under Rydberg condition through Shutalk effect and taken out as an ion beam 9 composed only of magnesium under the voltage between the electrodes 6, 8a to be irradiated onto a specimen 8. Consequently, the ionization efficiency and the selectivity of ion can be improved considerably.

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 the two laser beams Bl and B2 of 5528 people, that is, the magnesium atoms in the ground state 3s (13) are first ionized into 2
The first excited state 3p (
iPQ), 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 that synchrotron radiation, particularly relativistic synchrotron radiation, is used as the excitation light source. be.

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, the excited vapor is ionized, 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 conventional. The ionization method is different.

E (V/e11)-0,3125X10S-n-4 where 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, only the substance to be ionized can be ionized by selecting the energy level and wavelength of the synchrotron radiation so that they do not match those of the impurity atoms. It can be ionized and produces 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, l
1 is a container into which the substance to be ionized is introduced, la is a gas introduction hole for introducing the substance into the container 1, and 1b is
3 is an exhaust passage connected to a vacuum evacuation device (not shown) for evacuating the volume a1; 3 is a synchrotron radiation generating unit that generates synchrotron radiation B3 having a narrow wavelength width; 5; , 6 is the synchrotron radiation B
Electrodes 5a and 6a arranged across 3 are terminals for applying voltage to the electrodes 5 and 6, and these are terminals for applying an ionizing electric field to ionize the substance in the container 1. It consists of

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.

Then, from the synchrotron radiation light generating section 3, a wavelength of 16
The synchrotron radiation B3 of 25 people is introduced into the container 1, whereby the magnesium vapor 10 is radiated into the basal state by the radiation B3. @33 (IS) is resonantly excited to Niedberg state 29p (IPO).

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 light, thereby causing the Rydberg-like fi29p
An electric field is applied to the magnesium vapor 10 at (IPO), 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. 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 13, and the vapor 1
At the same time, a voltage is applied to the electrodes 5 and 6 to apply an electric field to the vapor 10. As a result, the vapor 10 is excited from the ground state 3 s (' S) to the Rydberg state j@29p (I PO), and further to the Rydberg state 29p (I PO) due to the Stark effect.
) electrons in the magnesium vapor 10 become free electrons, thereby generating magnesium ions, which are focused to the axis by the magnet 11 and then emitted as an ion beam 9 by the extraction electrode 14.

FIG. 4 shows an example of the configuration of a synchrotron radiation generating device used in the present invention. In FIG. 0, 21 is a linear accelerator, 22
is an electron storage ring, 23 is a wiggler, 24 is a spectroscopic system,
33 is a container.

In the synchrotron radiation introduced into the container 33, electrons are first accelerated by the linear accelerator 121 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. The ion beam is further introduced into the spectroscopic system 24 and made into a single wavelength by the spectroscopic system 24.The range of optical tunability can be expanded, and ion beams of various substances 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 into the Rydberg state by applying an electric field. Since the state is changed from an excited state to 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 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... Electric field generating section, 2
0... Synchrotron radiation generating section, B3... Synchrotron radiation light. Note that the same reference numerals in the figures indicate the same or equivalent parts. Agent: Masuo Oiwa (Volunteer to write the first drafting procedure amendment) 1. Indication of the case: Japanese Patent Application No. 59-66899 2, name of the invention, ion beam generator 3, person making the amendment Relationship to the case: Representative Hitoshi Katayama of the patent applicant, Department 4, Attorney 5, of the specification to be amended. Detailed Description of the Invention Column 6, Contents of Amendment (1) Rydberg 1, page 3, line 16
evel” is corrected to rRydberg 5tate J. (2) In the first line of page 8, change “electrodes in sync” to “1μs”.
Corrected to "electrode with some delay." (3) “Simultaneous electrode” on page 1O, line 13 of the same page [lμ
electrode after a delay of about s]. that's all

Claims (1)

[Claims] fυ A synchrotron comprising a container containing a substance to be ionized, and a synchrotron which resonantly excites the substance in the container by irradiating the substance with synchrotron radiation light so that the ground state of the energy level becomes the Rirudberg state. An ion beam generation device comprising: a synchrotron radiation generating section; and an electric field injection section that applies an electric field to the substance in the container to change it from a Rydberg state to an ion state by the Stark effect. (2) The ion beam generating device according to claim 1, wherein the synchrotron radiation light generating section includes an accelerator. (3) The ion beam generator according to claim 2, wherein an electron storage ring or an electron cyclotron is used as the accelerator. (41) The synchrotron radiation light generating section includes an accelerator and a spectrometer or spectroscopic system, and generates light of a single wavelength by passing the output from the accelerator through the spectrometer or spectroscopic system. Characteristic claim 2 or 3
The ion beam generator described in Section 1. (5) The synchrotron radiation generating section has a spectroscope or a spectroscopic system, and emits a plurality of single wavelengths that resonantly excite the substance stepwise from the ground state to the Rydberg state via the intermediate state. 2. The ion and ion generator according to claim 1, wherein the ion generator generates light.