JPH04262349A - Multi-valent heavy ion source and univalent heavy ion source - Google Patents

Abstract

PURPOSE:To provide a one-valent heavy ion source and a multi-valent heavy ion source for large current application. CONSTITUTION:An arc discharge electrode 2, gas introducing means 14, and magnetic field generating device 4 are furnished in a vacuum chamber 1, and the rare gas plasma produced is conveyed to a gap between flat plate electrodes 3 in parallel with one another. A magnetic field perpendicularly intersecting the electric field is impressed between these flat plate electrodes 3 by another mag. field generating device 5. A sputtering cathode 3a is bombarded with rare gas ions to make sputtering of the heavy ionmetal material. Plasma electrons make parallel advance magnetron motion, and plasma including univalent heavy ions is conveyed quickly to a cylindrical cavity 16. Using a solenoid coil 17, an axially directed magnetic field is impressed to this cylindrical cavity 16 to which microwaves are introduced to excite a vibration in the TEz210 mode. The plasma electrons makes cyclotron motion while absorbing the electric field energy due to ECR by the axially directed magnetic field and quadripolar high frequency electric field. Thereby multi-valent heavy-metal ions are produced in a large quantity.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multivalent heavy ion source and a monovalent heavy ion source used as ion beam sources in semiconductor manufacturing processes, surface modification of materials, and the like.

0002

[Background Art] In recent years, the demand for ion beam application equipment such as ion implantation equipment equipped with an ion source, which is a device for ionizing target elements (particles), has increased, and industrial equipment has been put into practical use. . However, regarding ion beam application equipment for large currents using heavy metal ions with high melting points, which is expected to be applied to wider fields such as metal surface modification,
It is difficult to put it into practical use. One of the reasons for this is that, in general, as the mass number M of ions increases, it becomes difficult to downsize the accelerator section and mass separation section of the device. For example, in the case of a mass separation unit using an electromagnet in an ion implanter, the strength of the magnetic field required to separate the ions to be used is (M/q
) 1/2, so the electromagnet itself needs to be larger for heavy ions than for light ions with a small M/q.

[0003] Therefore, a method for reducing M/q even with heavy elements is to use multiply charged ions with increased degree of ionization. When multiply charged ions are used, an ion beam with high energy higher than the accelerating voltage can be obtained and the device can be made smaller, so a multicharged heavy ion source is desired. However, conventionally, no multivalent heavy ion source for large currents has been found.

[0004] As a conventional multivalent ion source, the one shown in FIG. 6, an explanatory diagram of its configuration, is known (Junzo Ishikawa: Ion Source Engineering, p. 469, Ionics Co., Ltd.). This conventional multivalent ion source is called a microwave discharge type multivalent ion source, and as shown in FIG.
A monovalent ion generation chamber 51, a second ionization chamber 52, and a third ionization chamber 53 are provided in a vacuum chamber equipped with a vacuum pump for evacuation. Then, a gas as a raw material for target ions is introduced into the monovalent ion generation chamber 51 from the gas inlet 54 to a relatively high gas pressure, and the frequency is 1.
A 6 GHz microwave is introduced from the microwave inlet 55, and a magnetic field generating coil 56 provides a magnetic flux density that satisfies ECR (electron cyclotron resonance) conditions to generate high-density plasma. The plasma generated in this singly charged ion generation chamber 51 is flowed into the second ionization chamber 52 by a gentle magnetic field gradient.

In the second ionization chamber 52, ions are confined by a magnetic field generation coil 57 and a permanent magnet 58 arranged in a multipolar magnetic field, and a microwave with a frequency of 8 GHz lower than that in the singly charged ion generation chamber 51 is guided. Multivalent ions are generated by introducing plasma electrons through the inlet 59 and heating them by ECR absorption to obtain electrons that participate in multivalent ionization. Then, a magnetic field generating coil 6 is provided externally.
After further ionization by ECR absorption in the third ionization chamber 53 where 0 is placed, the target multiply charged ions are extracted as an ion beam 61 by an extraction electrode 62.

[0006]

[Problems to be Solved by the Invention] However, in the conventional multivalent ion source introduced above, plasma containing monovalent ions generated in the monovalent ion generation chamber 51 is diffused using a gentle magnetic field gradient caused by a mirror magnetic field. Since it is configured to transport to the ionization chambers 52 and 53 for obtaining multivalent ions using the ions, there is a drawback that the supply of ions to the ionization chambers 52 and 53 is restricted and it is difficult to obtain a large current. Therefore, in view of the drawbacks of the conventional multivalent ion sources, the present inventors have repeatedly researched multivalent heavy ion sources that can obtain large currents, and have devised the multivalent heavy ion source of the present invention. He also devised a singly charged heavy ion source that could generate large currents.

That is, an object of the present invention is to provide a multiply charged heavy ion source and a singly charged heavy ion source that can obtain a large current.

[0008]

[Means for Solving the Problems] In order to achieve the above object, a multiply charged heavy ion source according to the invention of claim 1 of the present application has the following features:
It has a plasma generation unit that converts rare gas into plasma by arc discharge in a vacuum chamber that is evacuated to a predetermined pressure, and a parallel plate electrode to which a DC voltage is applied in the vacuum chamber, and the rare gas ions in the plasma. a monovalent heavy ion generation and transport section that generates and transports target heavy ions in a monovalent form based on sputtering; and a cylindrical cavity that is evacuated to a predetermined pressure and communicates with the gap space of the parallel plate electrodes. A multiply charged heavy ion source comprising: a multiply charged heavy ion generating section for ionizing the monovalent heavy ions to produce multiply charged heavy ions; and an extraction electrode for extracting the multiply charged heavy ions. The plasma generation section includes an arc discharge electrode that has a cathode and an anode placed opposite thereto and performs arc discharge in a pulsed manner, and a rare gas introduced into the gap space between the arc discharge electrodes in synchronization with the arc discharge. and a means for generating a magnetic field in a direction perpendicular to the electric field between the arc discharge electrodes, in order to transport the rare gas plasma generated by the arc discharge to the gap space between the parallel plate electrodes by electromagnetic force. In the monovalent heavy ion generation/transport unit, the parallel plate electrode is constituted by a sputtering cathode whose surface is at least formed of a target heavy ion element material, and an anode disposed opposite thereto. and has means for generating a magnetic field in a direction perpendicular to the electric field between the parallel plate electrodes, and rare gas ions of the plasma from the arc discharge electrode gap impact the sputtering cathode with the electric field, thereby causing the sputtering cathode to ionizing the sputtered elemental material to contain the monovalent heavy ions by sputtering the elemental material and causing the electrons of the plasma to undergo translational magnetron motion along the sputtering cathode surface toward the cylindrical cavity by the orthogonal electromagnetic field; The multiply charged heavy ion generating section is configured to transport plasma to the cylindrical cavity, and the multiply charged heavy ion generating section includes means for generating an axial magnetic field within the cylindrical cavity, and a microwave for introducing microwaves into the cylindrical cavity. wave introduction means, and the cylindrical cavity is TEn10
Its shape and dimensions are determined so as to excite it in a mode (n is an integer of 2 or more), and the relationship between the frequency of the microwave and the strength of the axial magnetic field is determined by the 2·n multipole high-frequency electric field in the TEn10 mode. The electron cyclotron resonance condition is set to satisfy the electron cyclotron resonance condition of It is characterized in that it is designed to generate multivalent heavy ions.

Further, the monovalent heavy ion source according to the invention of claim 2 of the present application includes a plasma generation section that converts rare gas into plasma by arc discharge in a vacuum chamber that is evacuated to a predetermined pressure, and a a monovalent heavy ion generation/transport unit having parallel plate electrodes to which a DC voltage is applied, and generating and transporting target monovalent heavy ions based on sputtering with rare gas ions in the plasma; A monovalent heavy ion source is provided with an extraction electrode for extracting heavy ions, and the plasma generation section includes an arc discharge electrode that has a cathode and an anode placed opposite thereto and performs arc discharge in a pulsed manner. , gas introducing means for introducing a rare gas into the gap space between the arc discharge electrodes in synchronization with the arc discharge, and means for generating a magnetic field in a direction perpendicular to the electric field between the arc discharge electrodes, which is generated by the arc discharge. The generated rare gas plasma is transported to the gap space of the parallel plate electrodes by electromagnetic force, and the monovalent heavy ion generation/transport section is configured such that at least the surface of the parallel plate electrodes is capable of transporting target heavy ions. It is composed of a sputtering cathode made of an elemental material and an anode placed opposite to the sputtering cathode, and has means for generating a magnetic field in a direction perpendicular to the electric field between the parallel plate electrodes, and has a means for generating a magnetic field in a direction perpendicular to the electric field between the parallel plate electrodes. sputtering the elemental material by bombarding the sputtering cathode with rare gas ions of the plasma by the electric field, and causing electrons of the plasma to undergo translational magnetron movement along the sputtering cathode surface toward the extraction electrode by the orthogonal electromagnetic field. The device is characterized in that the sputtered elemental material is ionized and plasma containing monovalent heavy ions is transported toward the extraction electrode.

0010

[Operation] In the multi-charged heavy ion source having the above structure according to the invention of claim 1, first, in the plasma generating section, when a rare gas is introduced by the gas introduction means in synchronization with the arc discharge performed in a pulsed manner, At this time, the discharge space in the low pressure (high vacuum) vacuum chamber becomes a high pressure (low vacuum) state, and a high density rare gas plasma is generated. Since this rare gas plasma is applied with a magnetic field in a direction perpendicular to the electric field between the arc discharge electrodes, the electromagnetic force acting on the arc current quickly moves the rare gas plasma into the gap between the parallel plate electrodes of the monovalent heavy ion generation and transport section. transported to. Moreover, this makes it possible to minimize the diffusion and disappearance of rare gas plasma onto the vacuum chamber wall surface due to scattering with neutral particles.

In the monovalent heavy ion generation/transport section, an orthogonal electromagnetic field is applied between the parallel plate electrodes, so that the plasma electrons led from the gap between the arc discharge electrodes reach the sputtering cathode constituting the parallel plate electrodes. A translational magnetron moves along the surface in the direction of the cylindrical cavity of the multiply charged heavy ion generating section. Due to the translational magnetron motion of the plasma electrons, the rare gas ions bound by the electrons also begin to move in the same direction, accelerating the plasma mass itself.

[0012] As the plasma moves, rare gas ions in the plasma obliquely enter the sputtering cathode due to the electric field and impact the cathode, thereby sputtering the target heavy ion elemental material. Since rare gas ions are used, the above elemental materials are sputtered at a high sputtering rate. The sputtered elemental material is ionized by the collision of the electrons moving in the translational magnetron, and 1
Heavy valence ions are produced. The generated plasma containing monovalent heavy ions is accelerated by the translational magnetron motion of electrons, and a large amount of monovalent heavy ions are rapidly transported into the cylindrical cavity.

[0013] Then, the multiply charged heavy ion generation section is evacuated to a low pressure, and microwaves are introduced to generate TEn10.
In a cylindrical cavity excited by a mode (n is an integer of 2 or more),
A magnetic field is applied in the axial direction, and the frequency f of the microwave is
The relationship between B and the strength B of the axial magnetic field is as follows:
GHz)=n×27.992×B(Tesla). Therefore, in the cylindrical cavity, plasma electrons are exposed to an electric field due to ECR due to the magnetic field in the axis (beam axis) direction of the cylindrical cavity and the above-mentioned 2·n heavy pole high frequency electric field distributed perpendicularly to the axial direction of the cylindrical cavity. The cyclotron moves in the direction of the extraction electrode, drawing a spiral trajectory whose radius gradually increases while absorbing energy. As a result, the electrons collide with monovalent heavy ions guided from the heavy ion production and transport space and ionize them.
Multivalent heavy ions are generated one after another along with electrons.

Furthermore, the high-frequency electric field in the TEn10 mode (when n=2, it becomes a quadrupole electric field, and when n becomes a larger value, it becomes a caps coordination electric field) produces a strong focusing force on the ions, so that the ions Since it acts to make it difficult to approach the cylindrical cavity wall, the loss of generated multiply charged heavy ions can be reduced.

In the monovalent heavy ion source having the above configuration according to the second aspect of the invention, in the parallel plate electrodes to which an orthogonal electromagnetic field is applied, electrons of the plasma undergo translational magnetron movement along the sputtering cathode surface in the direction of the extraction electrode due to the orthogonal electromagnetic field. As a result, the generated plasma mass containing monovalent heavy ions is accelerated and rapidly transported toward the extraction electrode. As a result, the monovalent heavy ions have an initial velocity with respect to the extraction electrode, so the space charge restriction on the extraction electrode is relaxed, and it becomes possible to obtain a large current due to the monovalent heavy ions.

[0016]

[Examples] The present invention will be explained below based on Examples. [First Embodiment] FIG. 1 is an explanatory diagram of the overall configuration of a multicharged heavy ion source according to an embodiment of the invention as claimed in claim 1, and FIG. 2 is a magnetic field generation device of the plasma generation section of the multicharged heavy ion source shown in FIG. FIG. 3 is a diagram for explaining the translational magnetron motion of plasma electrons in the singly charged heavy ion generation and transport section of the multiply charged heavy ion source shown in FIG. 1, and FIG. 4 is a diagram for explaining the structure of the multiply charged heavy ion FIG. 3 is a diagram for explaining the cyclotron movement of plasma electrons in the multiply charged heavy ion generation section of the source.

In FIG. 1, 1 is a vacuum chamber that is evacuated to a predetermined pressure, and inside this vacuum chamber 1,
Along the central axis (beam axis), a pair of arc discharge electrodes 2 are composed of a discharge cathode 2a and a discharge anode 2b facing the discharge cathode 2a, and an anode 3b facing the sputtering cathode 3a. A pair of parallel plate electrodes 3 are sequentially arranged. Further, inside the vacuum chamber 1, a cylindrical first magnetic field generator 4, which will be described later, surrounds the arc discharge electrode 2 and serves as a means for generating a magnetic field in the direction shown in the figure perpendicular to the electric field between the arc discharge electrodes 2. A cylindrical second magnetic field generating device 5 as a means for generating a magnetic field in the direction shown in the figure perpendicular to the electric field between the parallel plate electrodes 3 is arranged so as to surround the parallel plate electrodes 3. It is set up. 1a and 1b are exhaust ports of the vacuum chamber 1.

As shown in the figure, 6 is an arc power supply device in which a switch 7 that is controlled to open and close in a pulsed (intermittent) manner, a DC power supply 8 for arc discharge, and a DC power supply 9 for cathode filament are connected in series. be. The arc discharge electrode 2 has its anode 2b connected to the positive terminal of the DC power source 8 for arc discharge via the switch 6a, and its cathode 2a connected to the negative terminal of the DC power source 8 for arc discharge. Further, a cathode filament 10 attached to this cathode 2a is connected to a negative terminal of a DC power source 9 for cathode filament.

An insulated gas nozzle 11 having a tip that communicates with the gap space of the arc discharge electrode 2 is fitted into the discharge cathode 2a, and this gas nozzle 11 is installed in a rare gas supply pipe 12. It is connected to a high-speed opening/closing valve 13 which is controlled to open and close in synchronization with the switch 7. In this embodiment, the gas introduction means 14 is the high-speed opening/closing valve 1
3 and a gas nozzle 11. The arc discharge electrode 2, the first magnetic field generator 4, the arc power supply device 6, and the gas introduction means 14 arranged in the vacuum chamber 1 constitute a plasma generation section.

The parallel plate electrode 3 consisting of the sputtering cathode 3a and anode 3b is connected to a DC power source 15 for applying an electric field.
It is connected to the. In this embodiment, the sputtering cathode 3a is formed by coating the surface of an electrode body made of Cu (copper) with Pt (platinum) as an elemental material for the target heavy ions. The parallel plate electrode 3 arranged in the vacuum chamber 1, the DC power source 15 for applying an electric field, and the second magnetic field generator 5 constitute a monovalent heavy ion generation and transport section.

Then, as shown in the figure, the vacuum chamber 1
The position on the ion extraction side is connected to the gap space of the parallel plate electrode 3 through a small hole, and the ion extraction hole 1 is connected to the other side.
A cylindrical cavity 16 made of copper is evacuated to a predetermined pressure and excited in TEn10 mode (n is an integer of 2 or more) with its central axis aligned with that of the vacuum chamber 1. They are placed in a consistent manner.

A solenoid coil 17 is disposed around the outer periphery of the cylindrical cavity 16, which has a substantially circular cross section, and which generates a magnetic field in the axial direction shown in the figure within the cylindrical cavity 16. A yoke 18 through which a portion of the magnetic flux passes is disposed so as to cover the shaped cavity 16. In this embodiment, the solenoid coil 17 and yoke 18 constitute means for generating a magnetic field in the cylindrical cavity 16 in its axial direction.

Reference numeral 19 denotes a microwave generator, and the microwaves generated by the microwave generator 19 are introduced into the cylindrical cavity 16 by propagating through a coaxial cable 20 and a coupler (coupler) 21 as microwave introduction means. It is now possible to do so. Note that in this embodiment, the cylindrical cavity 16 is made of TE210
Its diameter is approximately 12 cm so that it can be excited in the TE210 mode. To satisfy the resonance condition, the value of the magnetic field strength B is approximately 0.044 Te
It is set to be sla.

[0024] Cylindrical cavity 16, solenoid coil 17,
The yoke 18, the coaxial cable 20 for introducing microwaves, and the coupler 21 constitute a multiply charged heavy ion generation section. 22 is an exhaust port for evacuating the inside of the cylindrical cavity 13 to a predetermined pressure, 23 is an extraction electrode, and 24 is an ion extraction power source.

As shown in FIG. 2, the above-described first magnetic field generator 4 has a substantially rectangular cross section by connecting and integrating the permanent magnets 41a and 41b and the yokes 42a and 42b so that they face each other. A permanent magnet 43a is fixed to the inner peripheral wall of one of the opposing yokes 42a, and a permanent magnet 43a is fixed to the inner peripheral wall of the other yoke 42b.
Permanent magnet 43b with different magnetic poles facing a
is fixed. The first magnetic field generator 4 is configured such that the direction of magnetic lines of force from one permanent magnet 43b to the other permanent magnet 43a is in the direction shown by the arrow in the figure (Fig. 1 In , they are arranged with respect to the arc discharge electrode 2 from the front of the page to the back of the page.

The configuration of the second magnetic field generating device 5 is the same as that of the first one, so a description thereof will be omitted. In addition, in the second magnetic field generator 5, the strength of the magnetic field is
It is set to cause translational magnetron motion of plasma electrons, which will be described later.

The operation of the multiply charged heavy ion source configured as described above will be explained below with reference to FIGS. 1, 3 and 4. The vacuum chamber 1 and the cylindrical cavity 16 are 10-
It is evacuated to a low pressure of 6 Torr or less. first,
In the plasma generation section, when the switch 7 is turned on, a DC voltage is applied between the poles 2a and 2b of the arc discharge electrode 2 by the DC power source 8 for arc discharge, and the high-speed switching valve 13 is turned on, causing arc discharge. Electrode 2
In this example, Xe (xenon), Kr
Among rare gases such as (krypton), Xe gas is introduced. As a result, this gap space is 10-3 to 10-2To
A high pressure (low vacuum) state of about rr is reached, and the Xe gas is turned into plasma by arc discharge to generate high-density Xe gas plasma.

Since the first magnetic field generator 4 is applying a magnetic field in the direction shown in the figure perpendicular to the electric field between the poles 2a and 2b of the arc discharge electrode 2, this Xe gas plasma is generated by the parallel plate electrode 3. The electromagnetic force acting on the arc current rapidly transports the Xe gas toward the gap space, faster than the diffusion of the Xe gas. Moreover, this makes it possible to minimize the diffusion and extinction of the Xe gas plasma toward the wall surface of the vacuum chamber 1 due to scattering with neutral particles.

In the monovalent heavy ion generation and transport section, a DC power source 15 applies a voltage of 10 to 100 kV between the parallel plate electrodes 3.
At the same time, a second magnetic field generator 5 applies a magnetic field in the direction shown in the figure perpendicular to this electric field. As a result, X led from the gap space of the arc discharge electrode 2
When the e-gas plasma reaches the gap space of the parallel plate electrode 3, the electrons of the plasma undergo a translational magnetron movement along the sputtering cathode 3a surface in the direction of the cylindrical cavity 16 of the multiply charged heavy ion generation section by the above-mentioned orthogonal electromagnetic field. start.

Generally, in orthogonal electromagnetic fields between parallel plate electrodes, electrons return to the cathode in a circular arc with a constant curvature, are repelled, and trace a similar circular arc again, which is a so-called magnetron motion. However, in this case, as shown in Figure 3,
The Xe ions shown by white circles ○, which are restrained by the plasma electrons shown by black circles ●, must also move in translation in the 16 directions of the cylindrical cavity, so the electrons initially contract as shown in the figure. The ions draw an elliptical trajectory, and as the ion population accelerates, its trajectory gradually approaches the trajectory of normal magnetron motion. like this,
The magnetron motion of plasma electrons causes the plasma mass to be accelerated.

As the plasma moves, the Xe ions in the plasma, which have a velocity component in the direction of the cylindrical cavity 16, obliquely enter the sputtering cathode 3a due to the electric field and impact it. The Pt atoms indicated by the heavy circle ◎ are sputtered and replaced with them. In this case, since Xe ions, which are rare gas ions, are used, Pt atoms can be sputtered at a high sputtering rate.

The sputtered Pt atoms are ionized by collision with the electrons moving in the translational magnetron, and monovalent Pt ions are trapped in the plasma. Then, since the plasma mass itself containing the generated monovalent Pt ions is accelerated by the translational magnetron motion of the electrons, a large amount of monovalent Pt ions are quickly carried into the cylindrical cavity 16.

[0033] Then, the introduced microwave is confined and excited in the TE210 mode in the cylindrical cavity 1.
6, plasma electrons e are applied to the cylindrical cavity 1 by a solenoid coil 17, as shown in FIGS.
6 and a quadrupole high frequency electric field E distributed perpendicularly to the axial direction (in a perpendicular plane) of the cylindrical cavity 16, the radius increases while absorbing electric field energy by ECR. The cyclotron moves in the direction of the extraction electrode 23 while drawing a spiral trajectory that gradually becomes larger.

The cyclotron-moving electrons collide with the monovalent Pt ions introduced from the gap between the parallel plate electrodes 3 and ionize them, so that multivalent Pt ions are successively generated together with the electrons. These multivalent Pt ions are extracted by an extraction electrode 23 as an ion beam. In this case, the quadrupole high frequency electric field E in the TE210 mode generates a strong focusing force on the ions, and the ions are forced into the cylindrical cavity 16.
Since it acts to make it difficult to approach the wall, it is possible to reduce the loss of generated multivalent Pt ions.

As described above, the Xe gas plasma, which is a rare gas plasma generated by arc discharge, is quickly transported by electromagnetic force to the gap space between the parallel plate electrodes 3, and the parallel plate electrode 3 receives an orthogonal electromagnetic field. When Xe ions, which are rare gas ions, bombard the sputtering cathode 3a with an electric field, Pt atoms, which are the elemental material for the target heavy ions, are sputtered at a high sputtering rate, and the electrons of the plasma are sent to the sputtering cathode 3a by an orthogonal electromagnetic field. By the translational magnetron motion along the surface, the generated plasma mass containing monovalent Pt ions is accelerated, and a large amount of monovalent Pt ions are rapidly transported to the cylindrical cavity 16. Then, in the cylindrical cavity 16 where an axial magnetic field is applied and microwaves are introduced to excite it in the TE210 mode, the plasma electrons absorb the electric field energy due to ECR by the axial magnetic field and the quadrupole high frequency electric field. However, by the cyclotron movement, monovalent Pt ions are ionized and multivalent Pt ions are efficiently generated, and a large current (ion current) due to the multivalent Pt ions can be obtained.

[Second Embodiment] FIG. 5 is an explanatory diagram of the configuration of a monovalent heavy ion source according to an embodiment of the invention of claim 2. Figure 5
1, the same components as in FIG. 1 are indicated by the same reference numerals. As shown in FIG. 5, an extraction electrode 33 connected to an ion extraction power source 34 is provided at a position on the ion extraction side of the vacuum chamber 1, as shown in the figure. The other configurations are the same as those in FIG. 1 described above.

In the monovalent heavy ion source configured as described above, electrons of the plasma are caused by translational magnetron movement in the direction of the extraction electrode 33 along the surface of the sputtering cathode 3a by the orthogonal electromagnetic field at the parallel plate electrodes 3 to which an orthogonal electromagnetic field is applied. , monovalent Pt, which is a monovalent heavy ion produced
The plasma mass itself containing ions is accelerated and the extraction electrode 3
3 will be promptly transported. As a result, the monovalent Pt ions have an initial velocity with respect to the extraction electrode 33, so the space charge restriction on the extraction electrode 33 is relaxed, and a large current can be obtained by the monovalent Pt ions.

Note that the sputtering cathode 3a is as follows:
In the first and second embodiments above, the surface of the electrode body made of Cu is coated with Pt as the elemental material for the target heavy ions, but it goes without saying that the overall target It may also be formed from a heavy ion elemental material, such as tungsten, which is one of the heavy metals with a high melting point.

[0039]

As described above, in the multivalent heavy ion source according to the invention of claim 1, the rare gas is introduced by the gas introduction means in synchronization with the arc discharge of the arc discharge electrode, which is performed in a pulsed manner. Since the rare gas is turned into plasma under a high pressure (low vacuum) state, a high-density rare gas plasma can be generated. Since the generated rare gas plasma is quickly transported to the gap space between the parallel plate electrodes by the electromagnetic force of the magnetic field generating means, diffusion and extinction of the rare gas plasma to the wall surface of the vacuum chamber can be extremely reduced. Since a parallel plate electrode with a sputtering cathode and an orthogonal electromagnetic field applied thereto is provided, rare gas ions bombard the sputtering cathode with an electric field, thereby sputtering the target heavy ion elemental material with a high sputtering rate. can do. In addition, by the translational magnetron motion of plasma electrons along the sputtering cathode surface by the orthogonal electromagnetic field, the plasma mass itself containing the generated monovalent heavy ions is accelerated, and a large amount of monovalent heavy ions are sent into the cylindrical cavity. It can be transported quickly. An axial magnetic field is applied to this cylindrical cavity, and microwaves are introduced into the TEn10 mode (
n is an integer greater than or equal to 2), so
Monovalent heavy ions are ionized and multivalent heavy ions are efficiently generated by the cyclotron movement of electrons in the plasma while absorbing the electric field energy from ECR by the axial magnetic field and the 2·n multipole high-frequency electric field. be able to. Therefore, with this multiply charged heavy ion source, it is possible to obtain a large current due to multiply charged heavy ions.

According to the monovalent heavy ions according to the second aspect of the present invention, electrons in the plasma are caused by translational magnetron movement along the sputtering cathode surface toward the extraction electrode by the orthogonal electromagnetic field in the parallel plate electrodes to which the orthogonal electromagnetic field is applied. , the generated plasma mass containing monovalent heavy ions is accelerated and quickly transported toward the extraction electrode, so the monovalent heavy ions have an initial velocity with respect to the extraction electrode, and the The space charge limitation is relaxed, and a large current can be obtained by singly charged heavy ions. That is, according to the present invention, it is possible to provide a multiply charged heavy ion source and a singly charged heavy ion source that can obtain a large current.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the overall configuration of a multiply charged heavy ion source according to an embodiment of the invention of claim 1.

FIG. 2 is an explanatory diagram of the configuration of a magnetic field generator of the plasma generation section of the multivalent heavy ion source shown in FIG. 1;

FIG. 3 is a diagram for explaining translational magnetron motion of plasma electrons in the singly charged heavy ion generation and transport section of the multivalent heavy ion source shown in FIG. 1;

FIG. 4 is a diagram for explaining cyclotron motion of plasma electrons in the multiply charged heavy ion generation section of the multiply charged heavy ion source shown in FIG. 1;

FIG. 5 is a configuration explanatory diagram of a monovalent heavy ion source according to an embodiment of the invention of claim 2;

FIG. 6 is an explanatory diagram of the configuration of a conventional multivalent ion source.

[Explanation of symbols]

1... Vacuum chamber 1a, 1b... Exhaust port 2... Arc discharge electrode 2a... Cathode for discharge 2b... Anode for discharge 3... Parallel plate electrode 3a... Sputtering cathode 3b... Anode 4... First magnetic field generator 41a, 41b, 43a ，
43b...Permanent magnets 42a, 42b...Yoke 5...Second magnetic field generator
6... Arc power supply device 7... Switch 8... DC power supply for arc discharge 10...
Cathode filament 11...Gas nozzle 12...Gas supply pipe 13...High speed opening/closing valve 14...Gas introduction means 15...DC power source for applying electric field 16...Cylindrical cavity 1
7... Solenoid coil 18... Yoke 19... Microwave generator 20... Coaxial cable 21... Coupler 22... Exhaust port 23, 33... Extraction electrode 24,
34…Ion extraction power supply

Claims (2)

[Claims] 1. A plasma generation unit that converts rare gas into plasma by arc discharge in a vacuum chamber that is evacuated to a predetermined pressure, and a parallel plate electrode to which a DC voltage is applied in the vacuum chamber. A monovalent heavy ion generation/transport unit generates and transports target heavy ions in a monovalent form based on sputtering by rare gas ions in the ion, and a monovalent heavy ion generation/transport unit is evacuated to a predetermined pressure and is placed in the gap space between the parallel plate electrodes. A multivalent heavy ion generating section having a communicating cylindrical cavity and ionizing the monovalent heavy ions to generate multivalent heavy ions, and an extraction electrode for extracting the multivalent heavy ions. The plasma generation section is a heavy ion source, and includes an arc discharge electrode that has a cathode and an anode placed opposite thereto and performs arc discharge in a pulsed manner, and a gap space between the arc discharge electrode that is synchronized with the arc discharge. and a means for generating a magnetic field in a direction perpendicular to the electric field between the arc discharge electrodes. The monovalent heavy ion generation/transport unit is configured to transport the monovalent heavy ions into space, and the parallel plate electrode is arranged to face a sputtering cathode, at least the surface of which is formed of an elemental material for the target heavy ions. and an anode, and has means for generating a magnetic field in a direction perpendicular to the electric field between the parallel plate electrodes, and the rare gas ions of the plasma from the arc discharging electrode gap space are directed to the sputtering cathode by the electric field. The elemental material is sputtered by bombardment, and the orthogonal electromagnetic field causes electrons of the plasma to undergo translational magnetron movement along the sputtering cathode surface in the direction of the cylindrical cavity, thereby ionizing the sputtered elemental material to form this monovalent material. is configured to transport a plasma containing heavy ions to the cylindrical cavity, and the multiply charged heavy ion generating section includes means for generating an axial magnetic field within the cylindrical cavity, and a means for generating a magnetic field in the axial direction within the cylindrical cavity. The shape and dimensions of the cylindrical cavity are determined so that the cylindrical cavity is excited in the TEn10 mode (n is an integer of 2 or more), and the frequency of the microwave and the axial magnetic field are determined. The relationship between the strength of TEn
It is set to satisfy the electron cyclotron resonance condition by a 2·n high-frequency electric field in the 10 mode, and the electrons of the plasma are caused to undergo cyclotron movement in the direction of the extraction electrode by the axial magnetic field and the 2·n high-frequency electric field. A multiply charged heavy ion source characterized in that it is configured to generate multiply charged heavy ions by ionizing monovalent heavy ions. 2. A plasma generation unit that converts rare gas into plasma by arc discharge in a vacuum chamber that is evacuated to a predetermined pressure, and a parallel plate electrode to which a DC voltage is applied in the vacuum chamber; A monovalent heavy ion comprising a monovalent heavy ion generation/transport unit that generates and transports target monovalent heavy ions based on sputtering with rare gas ions in the monovalent heavy ion, and an extraction electrode for extracting the monovalent heavy ions. In the ion source, the plasma generation section includes an arc discharge electrode that has a cathode and an anode placed opposite to the cathode and performs arc discharge in a pulsed manner, and a gap space between the arc discharge electrode that is arranged in synchronization with the arc discharge. It has a gas introducing means for introducing a rare gas and a means for generating a magnetic field in a direction perpendicular to the electric field between the arc discharge electrodes, and the rare gas plasma generated by the arc discharge is applied to the gap between the parallel plate electrodes by electromagnetic force. The monovalent heavy ion generation/transport unit is configured to transport the monovalent heavy ions into space, and the parallel plate electrode is arranged to face a sputtering cathode, at least the surface of which is formed of an elemental material for the target heavy ions. and an anode, and has means for generating a magnetic field in a direction perpendicular to the electric field between the parallel plate electrodes, and the rare gas ions of the plasma from the arc discharging electrode gap space are directed to the sputtering cathode by the electric field. The elemental material is sputtered by bombardment, and the orthogonal electromagnetic field causes the electrons of the plasma to undergo translational magnetron movement along the sputtering cathode surface toward the extraction electrode, thereby ionizing the sputtered elemental material and converting it into monovalent ions. A monovalent heavy ion source, characterized in that it is configured to transport plasma containing heavy ions toward the extraction electrode.