JPWO2006115172A1 - Solid ion source - Google Patents

Abstract

An electron beam evaporation source 1 is used as an evaporation source for the solid material 2. In order to generate source plasma under a gas pressure that does not hinder the operation of the electron beam evaporation source 1, an electrode system 7 including a hot cathode 7a, an anode 7b, and an anti-cathode 7c is disposed in the plasma chamber, and high-frequency discharge is performed in the plasma chamber. To do. The neutral gas leaked to the ion beam drift unit 6 is adsorbed and recovered by the gas adsorbing member 15.

Description

  The present invention relates to a solid ion source for evaporating a metal or other solid substance at room temperature and ionizing it to generate an ion beam.

Conventionally, ion sources are used in ion implantation apparatuses, ion beam etching apparatuses, thin film manufacturing apparatuses, and the like. Among these ion sources, a device that evaporates a solid substance such as metal or the like at normal temperature, ionizes it, and generates an ion beam is usually called a “metal ion source”. As a typical example of a conventional metal ion source, one using a resistance heating crucible as an evaporation source and using arc discharge for generating a source plasma is known.
JP-A-4-202767 JP-A-4-306540 Japanese Patent Publication No.8-9777

The above-mentioned ion source has the following problems.
(1) In order to obtain a gas pressure necessary for arc discharge, for example, 0.8 × 10 ⁻¹ Pa, in the case of aluminum having a melting point of 660 ° C., the temperature of the crucible needs to be raised to about 1600 ° C. Therefore, it is difficult to obtain a necessary gas pressure with a raw material having a higher melting point than this, considering the durability of the crucible.
(2) Since the discharge gas pressure is high, the source gas leaked to the beam drift portion through the ion extraction hole may be solidified on the surface of the ion implantation target to become a coating film. This coating film prevents the beam ions from reaching the target surface layer.

  Accordingly, an object of the present invention is to provide a solid ion source that can generate an ion beam even with a high melting point raw material and can further prevent film formation due to solidification of the raw material gas on the surface of the ion implantation target.

  In order to achieve the above object, a solid ion source according to the present invention includes a vacuum container whose interior is evacuated, a raw material evaporation chamber having an electron beam evaporation source provided in the vacuum container and loaded with a solid raw material, and a vacuum container A plasma chamber that is provided with three electrodes comprising a hot cathode, a counter cathode, and an anode, introduces a source gas generated in the source evaporation chamber, generates a high frequency discharge between the three electrodes, and generates a plasma; And an ion extraction electrode portion provided in the container.

Since the electron beam (EB) evaporation source disposed in the raw material evaporation chamber can be easily subjected to position control and scanning control by an electromagnetic field or the like, the heating material surface can be controlled with an optimal electron beam current density. Since the power density of the electron beam can be increased, it is possible to evaporate all materials from refractory metals such as tungsten, molybdenum and tantalum to dielectrics such as SiO ₂ and AL ₂ O ₃ by using a single evaporation source. It is possible to generate a mixed ion beam containing ionic species from the solid source, and to switch between a plurality of solid sources easily and quickly.

In particular, the deflection electron beam evaporation source can be operated only under high vacuum (for example, 4 × 10 ⁻¹ Pa or less, preferably 7 × 10 ⁻² Pa or less) in order to prevent discharge in the electron gun section. Can not. On the other hand, arc discharge cannot be ignited or stably sustained under high vacuum, and is usually used under a pressure of about 10 Pa. Therefore, simply replacing the resistance overheating crucible of the conventional apparatus with an electron beam evaporation source does not generate arc discharge, and therefore an ion beam cannot be obtained.

In view of this point, in the present invention, three electrodes including a hot cathode, a counter cathode, and an anode are used, and high frequency discharge is generated between the three electrodes. This electrode system has a configuration in which each electrode is disposed coaxially and an anode is disposed between the hot cathode and the counter cathode. Between these electrodes, the thermoelectrons tandemly move between the three electrodes at high speed to cause high-frequency discharge, thereby generating plasma called swarm. Unlike plasma by arc discharge, this plasma can be stably generated and sustained even under a high vacuum of less than 10 ⁻¹ Pa required for the operation of the electron beam evaporation source.

In normal PIG discharge, the hot cathode and the counter cathode are used at the same potential, but when placed under a high vacuum as in the present invention, the swarm is confined in the space between the hot cathode and the counter cathode, The amount of ions reaching the extraction electrode portion is reduced. As a countermeasure, in the present invention, a positive potential higher than that of the hot cathode is applied to the counter cathode (for example, several tens of volts higher than that of the hot cathode), and a positive potential higher than that of the counter cathode is applied to the anode (for example, counter cathode) For example, several hundred volts higher). With this potential coordination, the swarm expands to the ion extraction electrode portion side by bipolar diffusion and reaches the electric field region of the ion extraction electrode portion. (Hereinafter, this discharge form is referred to as “deformed PIG discharge.”) When an ion acceleration voltage is applied to the ion acceleration electrode, ions are extracted from the source plasma and an ion beam is formed. Since this modified PIG discharge can be sufficiently ignited even at a low gas pressure (about 10 ⁻² Pa), which is about 1/100 of arc discharge, it is stable even under the high vacuum required for the operation of the electron beam evaporation source. Continuous discharge can be maintained.

  If the two types of discharge are superimposed by providing the above three electrodes and either the RF electrode or the microwave input part in the plasma chamber, the ionization degree of the source plasma increases, so that the current density of the ion beam Can be increased.

  Also, as one of the embodiments of the solid ion source of the present invention, a vacuum vessel whose inside is evacuated, a raw material evaporation chamber provided in the vacuum vessel and having an electron beam evaporation source loaded with a solid raw material, a vacuum An RF electrode or microwave input unit is provided in the container, and a raw material gas generated in the raw material evaporation chamber is introduced to generate RF discharge (high frequency discharge) or MW discharge (microwave discharge) to generate plasma. It comprises a plasma chamber and an ion extraction electrode part provided in the vacuum vessel.

The RF discharge and the MW discharge can be stably maintained even under a high vacuum lower than 10 ⁻¹ Pa required for the operation of the electron beam evaporation source. Accordingly, it is possible to generate a source plasma for performing stable discharge even under a low gas pressure and extracting an ion beam having a high ionization degree.

  In general, the current density of the ion beam is proportional to the ion density of the source plasma. Therefore, it is desirable that the gas pressure in the plasma chamber be high in order to increase the beam current if the degree of ionization is constant. On the other hand, if the gas pressure is too high, discharge occurs in the electron gun of the electron beam evaporation source as described above. Therefore, it is desirable to reduce the gas pressure around the electron beam evaporation source as much as possible.

  In order to meet this demand, in the present invention, the raw material evaporation chamber and the plasma chamber are partitioned by a partition wall having a vapor inlet, and an exhaust port is provided in the raw material evaporation chamber. By exhausting from the exhaust port, it is possible to increase the gas pressure in the plasma chamber while maintaining the raw material evaporation chamber at a low gas pressure. The evaporation gas generated in the raw material evaporation chamber moves to the plasma chamber through the vapor inlet. The raw material evaporation chamber and the plasma chamber communicate with each other through a steam inlet, but the raw material evaporation chamber is maintained at a gas pressure of about 1/10 of that of the plasma generation chamber by increasing the exhaust resistance of the steam inlet. Is possible.

Further, the same effect can be obtained by a discharge type in which a second anode is provided in the plasma chamber, which is opposed to the counter cathode and has a positive potential higher than the counter cathode (for example, about several 10 to 200 V). In this case, the modified PIG discharge becomes the first stage discharge, and the plasma generated by this discharge diffuses beyond the potential barrier of the counter cathode is used as a seed plasma, and when the positive potential of the second anode is raised, Arc discharge, which is a second-stage discharge, is induced in between. Neutral gas atoms in the excited state that were not ionized in the first stage discharge are also easily ionized, causing the discharge current to increase rapidly. Since these discharge phenomena are performed in a steady state in a steady state, a source plasma having a high degree of ionization can be formed.

  Further, if a magnetic field is formed on the outer periphery of the plasma chamber, the plasma can be confined in the radial direction. In addition, ions and electrons begin to perform a Larmor motion and the frequency of impact ionization increases. As a result, the ion density in the plasma increases and the ion beam density increases. As this type of magnetic field, in addition to a magnetic field formed by an air-core coil, a multicusp magnetic field using a permanent magnet or a mirror magnetic field can be employed.

  The ion beam that has passed through the ion extraction electrode portion is mixed with a neutral source gas that has not been ionized or recombined. When this neutral source gas drifts and adheres to the surface of the ion beam injection object, it is solidified to form a thin film. Ions having an energy of several tens of keV are stopped in the film even if the thickness of the thin film is submicron, and do not reach the surface of the injection target. Therefore, in the present invention, a gas adsorbing member that adsorbs a neutral gas is disposed behind the ion extraction electrode portion. As the gas adsorbing member, for example, a metal material cooled with a refrigerant such as liquid nitrogen can be used.

  In order to make a beam material such as tungsten or tantalum having a low vapor pressure into plasma by discharge, these high melting point materials are compounded with an element of low Z (atomic number), or a low Z discharge assist gas is mixed. Thus, there is a technique for increasing the gas pressure to easily cause discharge. When this method is applied to the ion source of the present invention, a low-Z impurity element is mixed in the ion beam. In order to solve this problem, in the present invention, an ion deflection magnet and a low Z ion annihilation member are provided behind the ion extraction electrode portion. Due to the magnetic field lines perpendicular to the beam formed by the ion deflecting magnet, the low-Z ions have a smaller Larmor radius in inverse proportion to the parallel root of the mass than high-Z ions such as tungsten, resulting in orthogonal to the magnetic field lines and the beam axis. Deviates from the beam axis in the direction of travel. Therefore, if the low Z ion annihilation member is formed of a metal material cooled with a refrigerant such as liquid nitrogen, for example, the low Z ions that are impurities are adsorbed on the low Z ion annihilation member, and the ion beam of the high melting point raw material is It is possible to drift while deflecting a little. The correction of the beam deflection can be performed by putting a bellow in the ion beam drift portion or making the ion implantation object movable.

  The hot cathode of the modified PIG discharge electrode system can be formed in a rod shape, a cylindrical shape or a conical shape. In this case, the tip of the hot cathode is preferably inserted inside the anode. It is desirable that each electrode of the modified PIG discharge electrode system is formed of tungsten, tantalum, or rhenium wire or a thin plate, and the temperature thereof is increased by overheating.

  If an ion beam of a solid material having a high melting point can be generated according to the present invention, an ion beam of any element can be formed regardless of whether it is solid or gas at room temperature. Except for the case of using a compound raw material or a discharge assist gas, it is not necessary to use an ion species deflecting magnet. Therefore, an ion source capable of forming a large area ion beam or an ion species mixed ion beam can be configured. it can.

  In addition, since it is possible to prevent a situation in which a non-ionized source gas adheres to an ion-implanted material and forms a film, the physicochemical application of ion implantation has greatly expanded. The usefulness of high-density, large-area ion beams containing ionic species of all elements in any content ratio, combined with the characteristics of non-thermal equilibrium treatment of ion implantation, is increasing with the progress of engineering methodology, molecular dynamics, and nanotechnology. It is beginning to be recognized in a wide range of fields. Specific issues include development of next-generation semiconductor non-volatile memory, research on sptronics, bio-inorganic organic / inorganic polymerization, chemical synthesis such as catalyst production, non-thermal equilibrium material surface dry process, and novel use in nanotechnology such as micromachines. Is expected.

  FIG. 1 shows a schematic configuration of a solid ion source according to the present invention.

As shown in the figure, this solid ion source has a raw material evaporation chamber 3, a plasma chamber 4, an ion extraction electrode portion 5, and an ion beam drift portion 6 disposed in a vacuum vessel 8, and is directed upward in order. It has a stacked configuration. Other than the raw material evaporation chamber 3, it can also be set horizontally. The entire vacuum vessel 8 is exhausted from the main exhaust port 21 to approximately 10 ⁻⁴ Pa before the operation of the apparatus. The vacuum vessel 8 is grounded.

  An electron beam evaporation source 1 is disposed in the raw material evaporation chamber 3. The electron beam evaporation source 1 in the illustrated example is a deflection type, and the electron beam is guided to the solid raw material 2 placed on the hearth (raw material tray) by Lorentz force and evaporated. It is also possible to use a large electron beam evaporation source capable of independently evacuating the electron beam generating part and the hearth part. In this case, the electron beam generating chamber is attached to the raw material evaporation chamber 3.

The electron beam evaporation source 1 cannot be stably operated unless under a low gas pressure in order to prevent discharge with an electron gun. For example, in an evaporation source with an acceleration voltage of 10 kV and a maximum power injection amount of 3 kW, the atmospheric gas pressure needs to be 3 × 10 ⁻¹ Pa or less. In order to realize this high degree of vacuum, the raw material evaporation chamber 3 is provided with a raw material evaporation chamber exhaust port 22 in addition to the main exhaust port 21, and the raw material evaporation chamber 3 and the plasma chamber 4 are connected to the vapor inlet port 11a. It is divided with the partition 11b which has. By exhausting from the raw material evaporation section exhaust port 22 during operation, the atmospheric gas pressure in the raw material evaporation chamber 3 can be made lower than the gas pressure in the plasma chamber 4. It is desirable that the steam inlet port 11a has a structure in which exhaust resistance is increased as much as possible. Further, the steam inlet 11a is preferably connected to an appropriate heating source to raise the temperature in order to prevent evaporation gas from adhering and solidifying.

  The electron beam evaporation source 1 can evaporate any substance compared to a heater-heated crucible, the heating time is short, the hearth is water-cooled, so there is less mixing of the hearth material into the evaporation gas, multiple-rotation hearth and multiple simultaneous operation Some types have advantages such as quick switching of a plurality of types of raw materials 2 and the ability to selectively change the mixing ratio of raw material gases. By adopting the electron beam evaporation source 1 for the evaporation of the solid material 2, it is possible to generate an ion beam of all elements from a solid high melting point material to a gaseous material.

  The source gas generated in the electron beam evaporation source 1 enters the plasma chamber 4 through the vapor inlet 11a. A modified PIG electrode system 7 is disposed in the plasma chamber 4. The electrode system 7 is disposed between the hot cathode 7a, the counter cathode 7c to which a positive bias potential higher by several tens of volts than the hot cathode 7a is applied, and the both cathodes 7a and 7c. It consists of an anode 7b to which a positive potential higher by 100V is applied, and these three electrodes are arranged coaxially. Each of the electrodes 7a to 7c is connected to a heating power source outside the vacuum vessel 8, and can be heated by energization. Each electrode 7a-7c is covered with the ion reflecting plate 9 heated to high temperature. Outside the vacuum vessel 8 on the outer periphery of the plasma chamber 4, air-core coils 10a and 10b that generate magnetic fields having orthogonal components with respect to the electric fields between the electrodes 7a to 7c are arranged. A magnetic field is formed inside the plasma chamber 4. Since the plasma is confined in the radial direction by this magnetic field, the ion density can be further increased. Although FIG. 1 illustrates the case where two air-core coils 10a and 10b are arranged on the outer periphery of the plasma chamber 4, one or both of these air-core coils may be omitted if not necessary. it can.

  When the hot cathode 7a is heated to generate thermoelectrons, the thermoelectrons tandemly move between the three electrodes at high speed, and high frequency discharge is performed to generate plasma called swarm. In particular, when the potential of the counter cathode 7c is set to a potential configuration that is several tens of volts higher than that of the hot cathode 7a (hereinafter referred to as “modified PIG potential”), the swarm expands in the direction of the ion extraction electrode portion 5 by bipolar diffusion. Due to this expansion, ions are extracted from the plasma by the ion extraction electrode portion 5 of the electrostatic electrode system. The ion extraction electrode 5 includes a plasma electrode 12, an ion acceleration electrode 13, and an ion deceleration electrode 14. Ions accelerated by the ion extraction electrode are introduced into the ion beam drift unit 6 as a beam, and pass through the vicinity of a gas adsorbing member 15 and a low-Z ion annihilation member 17 which will be described later, and are injected into an ion implantation not shown. Is done.

Since this modified PIG electrode can be sufficiently ignited even at a low gas pressure (about 10 ⁻² Pa) of about 1/100 of arc discharge, it is active even under the high vacuum required for the operation of the electron beam evaporation source. Source discharge can be generated.

  In the illustrated example, the anode 7b and the counter cathode 7c are both cylindrical as shown in FIG. 2a. For example, the anode 7b has a diameter × 60 mm × 20 mm and the counter cathode 7c has a size of 45 mm × 10 mm. used. The hot cathode 7a is formed of a 1 mmφ tungsten wire in a conical spiral shape. The electrode gap between the anode 7b and the hot cathode 7a and the counter cathode 7c is 15 mm, respectively. As the hot cathode 7a, the anode 7b, and the counter cathode 7c, as shown in FIG. 2b, the shape is cylindrical and alternately displaced in the axial direction for the purpose of increasing the electric resistance value, and the spiral as shown in FIG. 2c. It can also be formed in a cylindrical shape. The hot cathode 7a can also be formed in a round bar shape as shown in FIG. 2d.

With this electrode configuration, the raw material gas was introduced into the plasma chamber 4 at a gas pressure in the range of ² to 5 × 10 ⁻² Pa and the hot cathode 7a was heated to about 2000 ° C., and the other electrodes 7b and 7c were energized and heated. The discharge was easily started even when the air core coil 10a was not energized. Of course, if the electrodes 7b and 7c other than the hot cathode 7a are energized and heated, or the air-core coils 10a and 10b are energized and discharged in a state where a magnetic field is formed, the ion density can be further increased. The above gas pressure is merely an example, and the discharge gas pressure varies depending on the type of gas, the geometry and dimensions of the electrodes, the voltage applied to each electrode, the strength of the magnetic field, and the like.

  When the source gas is a gas element at normal temperature, a gas supply port 18a can be provided in the plasma chamber 4, and the gas source can be directly supplied to the plasma chamber 4 from the supply port 18a for ionization. Reference numeral 18 b in FIG. 1 is a plasma chamber vacuum measurement port for measuring the gas pressure in the plasma chamber 4.

  In order to increase the ion density in the plasma chamber 4, in addition to increasing the gas pressure, the ionization rate itself may be increased by increasing the density of thermoelectrons that perform tandem motion. For example, the hot cathode 7a of the plasma chamber 4 is made of tungsten, tantalum, titanium alloy, or a material such as tritungsten tungsten, rhenium, titanium alloy, a thin plate having a thickness of 0.1 to 0.2 mm, or FIG. When it is connected to a low voltage high current power source, for example, 10V / 300A, AC, provided outside the vacuum vessel, and heated by energization and heating, the plasma chamber 4 increases with the voltage of the anode 7b. It has been found that the ion density of the ion appears as a significant and simple increase in anode (discharge) current, and the ion beam current also increases monotonically very effectively without loss of convergence. If the anode voltage is increased too much, the ion temperature increases and the convergence of the ion beam may deteriorate.

  The ion density can be increased by surrounding the plasma chamber 4 with a magnetic field generated by the air-core coils 10a and 10b, or by surrounding the plasma chamber 4 with a multicusp magnetic field using a permanent magnet or a mirror magnetic field. it can.

  There is an optimum value for the strength of the magnetic field, and if this is too strong, the spatial distribution of the plasma becomes non-uniform, which affects the convergence of the ion beam. In the example of the above electrode dimensions, the optimum value of the magnetic field strength at the center of the electrode was about 100 to 300 Oe. Increase the beam current by making adjustments according to operating conditions such as gas pressure, ion species, ion acceleration voltage, external magnetic field strength, and discharge voltage without compromising ion beam convergence. Can do.

  By the way, depending on the vapor pressure of the solid raw material 2, the gas pressure of the plasma chamber 4 may be high. In this case, the ionization degree of the source plasma can be increased by performing two-stage discharge using the modified PIG discharge and the low gas pressure arc discharge shown in FIG. FIG. 3 shows an example thereof. The difference from the ion source shown in FIG. 1 is that the positive potential in the plasma chamber 4 is opposed to the counter cathode 7c and is, for example, several tens to 200V higher than the counter cathode 7c. The second anode 7d having the above is provided. The potential of the second anode 7d is set lower than that of the anode 7b.

  In this configuration, the modified PIG discharge by the three electrodes 7a to 7c is the first stage discharge. When the plasma generated by this discharge diffuses to the ion extraction region beyond the counter cathode 7c, arc discharge (second stage discharge) may occur between the second anode 7d and the counter cathode using this as a seed plasma. it can. As a result, a high-density source plasma with a very high degree of ionization could be formed even under a low gas pressure that does not cause discharge inside the electron gun of the electron beam evaporation source 1. The second anode 7d may be provided below the hot cathode 7a.

  FIG. 4 shows the measurement of discharge voltage versus discharge current characteristics in the first stage discharge and the second stage discharge in the electrode configuration shown in FIG. The curve A of FIG. 4 shows the same electrode voltage, that is, the discharge voltage when the applied voltage of the anode 7b is gradually increased, and the vertical axis indicates the same electrode current, that is, the discharge current. Voltage-current characteristics are shown. When the voltage of the second anode 7d is gradually increased in a state where the first discharge current is saturated, the second stage discharge is ignited, and at the same time, the voltage of the anode 7b rapidly drops as shown by the dotted line B in FIG. The second stage discharge current begins to flow, and the discharge current increases rapidly as shown by the C curve along with the voltage. Thus, the plasma with a low discharge voltage and a high ionization degree satisfies the conditions as a source plasma for obtaining an ion beam with good convergence, and a new discharge form has been completed.

There is an optimum value for the gap between the plasma electrode 12 and the ion acceleration electrode 13. For example, as the unit hole of the porous ion extraction electrode, ion extraction holes having diameters of 5.0 mm and 4.5 mm are provided coaxially in the plasma electrode 12 and the ion acceleration electrode 13, respectively, and the beam passage hole of the ion deceleration electrode 14 is provided. When the gap between the front two electrodes is 3 mm, the gap between the ion accelerating electrode 13 and the ion decelerating electrode 14 is 2 mm, and the ion decelerating voltage is fixed at 1.5 kv, an ion beam of 5 mAcm ⁻² is obtained at an ion extraction voltage of about 6 kV. Could be formed. The beam increased in convergence as the extraction voltage increased, but it became overfocused at 25 kV. In addition, discharge between the ion extraction electrodes occurred at a maximum acceleration voltage of about 35 kV.

  At this time, it has been clarified that the gap between the ion acceleration electrode 13 and the plasma electrode 12 has a strong influence on the convergence and the convergence distance of the ion beam. Therefore, in the present invention, an adjustment mechanism 20 that adjusts the gap between the two electrodes is provided between the ion acceleration electrode 13 and the plasma electrode 12. The adjusting mechanism 20 is configured such that the space between the electrodes is sealed with a bellow 20a or the like and can be expanded and contracted, and the gap between the electrodes can be adjusted from the outside with an electrode gap adjuster 20b such as a cylinder or a ball screw. is there.

  In the above description, the cross-sectional geometry of the three electrodes 7a, 7b, 7c of the plasma chamber 4 is an axisymmetric circle, but each electrode 7a, 7b, 7c has a rectangular shape with, for example, a short side of about 50 mm and a long side of about 1 m. Even if it is shaped and its surface is arranged along the axial direction, discharge by tandem motion of electrons can be similarly performed. In this case, the magnetic field surrounding the plasma chamber 4 is correspondingly large, the number of electron beam evaporation sources 1 is increased to 3-5, and the size of each ion extraction port of the ion extraction electrode unit 5 is also correspondingly large. Say it. Thereby, a large-area metal ion source capable of forming a sheet-like ion beam is configured. If the vacuum vessel is configured to be evacuated by a large capacity working exhaust, it can be used for industrial use such as continuous ion implantation into a long metal or polymer material.

  The non-ionized or recombined neutral source gas 23 diffused from the ion extraction port of the ion extraction electrode unit 5 to the ion beam drift unit 6 is adsorbed by the gas adsorption member 15 arranged in the ion beam drift unit 6. The gas adsorbing member 15 is formed of, for example, a metal plate cooled with a cooling medium such as liquid nitrogen. The neutral source gas 23 is adsorbed by the gas adsorbing member 15, so that a film of the neutral source gas 23 is not formed on the surface of the ion beam injection target, and the ion beam is reliably injected into the target surface. be able to.

  When a source material having a low vapor pressure is used as source plasma, there is a case where the gas pressure is increased by mixing a discharge assisting gas into the plasma chamber 4 in order to easily generate plasma. In this case, the support gas is also mixed into the ion beam. Therefore, the discharge assisting gas is limited to low atomic number elements such as hydrogen and helium, and as shown in FIG. 1, an ion deflection magnet 16 is provided in the ion beam drift portion 6 and a low Z ion annihilation member 17 is provided downstream thereof. When a magnetic field orthogonal to the ion beam is generated, the low Z source ions 24 are more easily deviated from the beam axis because the degree of deflection is stronger than that of the high Z ions. The low Z ions are adsorbed on the low Z ion extinction member 17, and the ion beam 25 of the solid material can be injected into the injection target while being slightly deflected. Note that if the intensity of the ion deflection magnetic field is slowly changed, there is also an effect of uniformizing the dose of source ions.

  When a plurality of solid source materials are evaporated simultaneously with a plurality of hearths, or when a plurality of electron beam evaporation sources are provided in the source evaporation chamber 3 and the electrode structure is enlarged as described above, a plurality of solid source ions A large area ion beam consisting of seeds can be formed.

  FIG. 5 shows another configuration example of the solid ion source.

  In the ion source having this configuration, an RF electrode 27 is disposed in the plasma chamber 4 in addition to the three electrodes 7a to 7c. The solid source 2 is vaporized by the electron beam evaporation source 1 installed in the vacuum vessel 8, the source gas is ionized by high frequency discharge at the RF electrode 27 to generate source plasma, and the ion beam is extracted by the ion extraction electrode 5. I am doing so.

In particular, in the illustrated example, the modified PIG discharge electrode system 7 is disposed in a plasma region generated by RF discharge. That is, the RF output coil 27 and the mature cathode 7a of the modified PIG discharge electrode system 7 are disposed immediately above the electron beam evaporation source 1 installed in the vacuum vessel 8. The anode 7b is arranged on the upper part, and the counter cathode 7c is further arranged on the upper part. The geometric shape of each electrode is determined according to the cross-sectional shape of the ion beam, and is circular or rectangular. Further, the hot cathode is made into a solenoid or conical shape with a thin wire such as tungsten or tantalum, and the tip thereof is arranged at the center of the anode 7b. On the other hand, air-core coils 10 a and 10 b are arranged on the outer periphery of the modified PIG electrode system 7. As a result, electrons in the RF discharge and the modified PIG discharge perform magnetron motion, increasing the degree of difficulty. Further, a multi-strip or porous ion extraction electrode unit 5 is provided for the source plasma diffused in the upper space of the modified PIG discharge electrode system 7 to increase the area of the beam. When the electron beam evaporation source 1 is operated at a degree of vacuum of about 10 ⁻³ Pa, an ion extraction voltage of about 10 to 25 kVdc can be applied, and a high-purity DC ion beam can be obtained without an ion species discrimination magnetic field. In the figure, reference numeral 26 denotes a shutter, and reference numeral 19 denotes an observation window.

  Even in this configuration, if an electron beam evaporation source of a type that simultaneously evaporates solids in a plurality of harnesses is used, an ion beam source including a plurality of ion species can be formed. Further, in order to obtain an ion beam of a gaseous element at room temperature, a small amount of ionized source gas may be directly introduced into the discharge part from the outside of the ion source. It is also possible to generate a mixed ion species beam of a solid material and a gas material. Instead of the RF electrode 27 described above, an MW (microwave) input unit may be installed in the plasma region of the plasma chamber 4. The MW input unit can be configured by an antenna in addition to the waveguide. Further, the modified PIG discharge electrode system 7 can be omitted, and an RF electric field or MW field only can be used as an ion source. The above configuration can solve the problem.

  The expansion of the beam cross-sectional area can form an ion beam having a diameter of about 30 cm in the case of a circular cross section. In the case of a rectangular cross section, if a plurality of electron beam evaporation sources 1 are used and the electrodes 7a to 7c of the modified PIG discharge electrode system and the magnetic field coil are rectangular, a sheet-like ion beam having a width exceeding 1 m can be formed.

  In the configuration shown in FIG. 5, an arc discharge electrode can be installed instead of the RF electrode 27. Incidentally, although RF discharge or arc discharge is easy to discharge in a region where the gas pressure is higher than 100 Pa, a linear electron gun having a structure capable of differentially evacuating the electron beam generating portion, the hearth portion and the plasma chamber was used. When the electron beam evaporation source 1 is used, the evaporation gas pressure in the plasma chamber 4 can be increased while avoiding the discharge of the electron gun.

  With the above configuration, ion implantation of all elements can be performed on the surfaces of various materials. Therefore, through various kinds of direct surface modification, various coating processes (for example, PVD, CVD, wet / dry plating, spraying, etc.), pretreatment (for example, carbonization, nitridation, oxidation, etc.) for the purpose of controlling interface physical properties, etc. It is possible to achieve effects such as improved affinity between the surface and working atoms, improved adhesion, improved thermal / electrical / mechanical physical properties of the interface, imparted gradient functionality, and reduced processing time.

It is sectional drawing which shows schematic structure of the solid ion source concerning this invention. It is a perspective view which shows the structural example of an electrode. It is a perspective view which shows the structural example of an electrode. It is a perspective view which shows the structural example of an electrode. It is a perspective view which shows the structural example of an electrode. It is sectional drawing which shows the other structural example of this invention. It is a figure which shows the measurement result of the discharge voltage V and the discharge current I in a plasma chamber. It is sectional drawing which shows the other structural example of the ion source concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electron beam evaporation source 2 Solid raw material 3 Raw material evaporation chamber 4 Plasma chamber 5 Ion extraction electrode part 6 Ion beam drift part 7 Modified PIG electrode system 7a Hot cathode 7b Anode 7c Counter cathode 7d Second anode 8 Vacuum vessel 9 Ion reflector 10a Air core coil 10b Air core coil 11a Steam inlet 11b Partition wall 12 Plasma electrode 13 Ion acceleration electrode 14 Ion deceleration electrode 15 Gas adsorbing member 16 Ion deflection magnet 17 Low Z ion extinguishing member
18a Gas supply port 18b Discharge chamber vacuum measurement port 19 Viewing window 20a Bellow,
20b Electrode gap adjuster 21 Main exhaust port 22 Raw material evaporation chamber exhaust port 23 Diffusion gas particle 24 Discharge sustaining low Z gas ion 25 High-speed metal ion beam
26 Shutter 27 RF electrode

Claims (9)

A vacuum vessel whose interior is evacuated,
A raw material evaporation chamber provided in a vacuum vessel and having an electron beam evaporation source loaded with a solid raw material;
A plasma chamber that is provided in a vacuum vessel and includes three electrodes including a hot cathode, a counter cathode, and an anode, introduces a source gas generated in a source evaporation chamber, and generates a plasma by generating a high frequency discharge between the three electrodes. When,
A solid ion source comprising an ion extraction electrode portion provided in a vacuum vessel.   2. The solid ion source according to claim 1, wherein the three electrodes, the RF electrode, or the microwave input unit are provided in the plasma chamber. A vacuum vessel whose interior is evacuated,
A raw material evaporation chamber provided in a vacuum vessel and having an electron beam evaporation source loaded with a solid raw material;
A plasma chamber that is provided in a vacuum vessel, includes an RF electrode or a microwave input unit, introduces a source gas generated in the source evaporation chamber, generates RF discharge or MW discharge, and plasma;
A solid ion source comprising an ion extraction electrode portion provided in a vacuum vessel.   The solid ion source according to claim 1, wherein a positive potential higher than that of the hot cathode is applied to the counter cathode and a positive potential higher than that of the counter cathode is applied to the anode.   The solid ion source according to claim 1 or 2, wherein a second anode facing the counter cathode and having a higher positive potential than the counter cathode is disposed in the plasma chamber.   4. The solid ion source according to claim 1, wherein a magnetic field is formed on the outer periphery of the plasma chamber.   The solid ion source according to claim 1 or 3, wherein the raw material evaporation chamber and the plasma chamber are partitioned by a partition having a vapor inlet, and an exhaust port is provided in the raw material evaporation chamber.   The solid ion source according to claim 1 or 3, wherein a gas adsorbing member that adsorbs a neutral gas is disposed behind the ion extraction electrode portion.   The solid ion source according to claim 1 or 3, wherein an ion deflection magnet and a low Z ion annihilation member are provided behind the ion extraction electrode portion.

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