Ion source

Abstract

To continuously supply steam from a vaporizer to a plasma generation chamber regardless of an operation state of an ion source.SOLUTION: An ion source IS includes: a vaporizer 1 having a nozzle 3; and a plasma generation chamber 14 to which vapor is supplied from the vaporizer 1 through the nozzle 3. The nozzle 3 is disposed outside the plasma generation chamber 14. The plasma generation chamber 14 has a first wall 14a and a second wall 14b facing each other. The second wall 14b has a first part 14b1 and a second part 14b2 at different positions in a facing direction of the first wall 14a and the second wall 14b, and has a third part 14b3 between the first part 14b1 and the second part 14b2. The second part 14b2 or the third part 14b3 has an opening H for supplying the vapor from the vaporizer 1 to the plasma generation chamber 14.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to an ion source that supplies vapor from a vaporizer to a plasma generation chamber and extracts an ion beam from the plasma generation chamber. [Background technology]

[0002] Ion sources used in ion implantation systems primarily use vaporizers to generate metal ions. The vaporizer receives solid metal in a crucible and generates metal vapor by increasing the crucible temperature. The vapor is then supplied to a plasma generation chamber through a nozzle attached to the crucible.

[0003] A plasma is generated from the supplied vapor in the plasma generation chamber, and an ion beam is extracted from the generated plasma.

[0004] In conventional ion sources, the tip surface of the vaporizer nozzle, that is, the end of the vaporizer nozzle that emits vapor, is arranged flush with the inner wall of the plasma generation chamber or inside the inner wall. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2023-154377 [Patent Document 2] Patent Publication No. 2023-172015 Summary of the Invention [Problem to be solved by the invention]

[0006] The operating state of the ion source changes depending on the beam current and ion species of the extracted ion beam. As the input power during operation of the ion source increases, the temperature of the plasma generated in the plasma generation chamber increases.

[0007] If the nozzle end is flush with the inner wall of the plasma generation chamber or positioned inside the inner wall, it is exposed to high-temperature plasma, increasing the risk of erosion and deformation of the nozzle end. If the nozzle end is deformed, it becomes difficult to continue vapor supply, and at some point it becomes necessary to stop operation of the ion source and replace the nozzle. This nozzle replacement reduces the availability of the ion source.

[0008] Therefore, a main object of the present invention is to provide an ion source that can continuously supply vapor from a vaporizer to a plasma generation chamber regardless of the operating state of the ion source. [Means for solving the problem]

[0009] The ion source is a vaporizer having a nozzle; a plasma generation chamber to which vapor is supplied from the vaporizer through the nozzle, the nozzle is disposed outside the plasma generation chamber, the plasma generation chamber has a first wall and a second wall facing each other, the second wall has a first portion and a second portion at different positions in a direction in which the first wall and the second wall oppose each other, and a third portion between the first portion and the second portion; The second portion or the third portion has an opening for supplying the vapor from the vaporizer to the plasma generation chamber.

[0010] Another ion source is a vaporizer having a nozzle and configured to generate vapor; a plasma generation chamber that receives the vapor from the nozzle, the plasma generation chamber has a first wall and a second wall facing the first wall, the second wall has a protrusion protruding toward the first wall, the nozzle is disposed on the protrusion outside the plasma generation chamber; The protrusion has an opening through which the vapor is supplied into the plasma generation chamber.

[0011] Other ion sources include a vaporizer having a nozzle; a plasma generation chamber for generating plasma, The plasma generation chamber comprises: a first wall having an ion extraction opening; a second wall that faces the first wall in the axial direction of the nozzle, the second wall including a protruding portion that protrudes into the plasma generation chamber and has a recess in which an end of the nozzle is disposed; The protrusion includes an opening in fluid communication with the interior of the plasma generation chamber. [Effects of the Invention]

[0012] The nozzle for supplying the vapor is located outside the plasma generation chamber, and the vapor from the vaporizer is supplied into the plasma generation chamber through an opening formed in the wall of the plasma generation chamber. With this configuration, the nozzle is not exposed to the plasma generated in the plasma generation chamber, preventing erosion of the nozzle end by high-temperature plasma and enabling continuous vapor supply. [Brief explanation of the drawings]

[0013] [Figure 1] Schematic cross-sectional view of the ion source [Figure 2] An enlarged view of area A shown in FIG. [Figure 3] A perspective view of a wall surface of a plasma generation chamber having a protrusion [Figure 4] Plan view of the wall of the plasma generation chamber having a protrusion [Figure 5] Schematic cross-sectional view of the ion source [Figure 6] Schematic cross-sectional view of the ion source in Figure 5 as seen from the ZX plane [Figure 7] Schematic cross-sectional view of the ion source [Figure 8] Schematic cross-sectional view of the ion source [Figure 9] Schematic cross-sectional view of the ion source [Figure 10] Schematic cross-sectional view of the ion source [Figure 11] Schematic cross-sectional view of the ion source [Figure 12] Schematic cross-sectional view of the ion source in Figure 11 as seen from the YZ plane [Figure 13] Schematic cross-sectional view of the ion source [Figure 14] Schematic cross-sectional view of the ion source [Figure 15] Schematic cross-sectional view of the ion source [Figure 16] Schematic cross-sectional view of the ion source DETAILED DESCRIPTION OF THE INVENTION

[0014] FIG. 1 is a schematic cross-sectional view of an ion source IS according to some embodiments. The ion source IS is shown as an indirectly heated ion source by way of example. However, the ion source IS of the present invention is not limited to an indirectly heated ion source. A filament 16 heats a cathode 15, which emits ionization electrons into a plasma generation chamber 14. The plasma generation chamber 14 is a substantially rectangular or cubic container. A reflecting electrode 17 is disposed opposite the cathode 15 to reflect electrons from the cathode 15. In FIG. 1, an external electromagnet (not shown) generates a magnetic field within the plasma generation chamber 14 along a direction connecting the cathode 15 and the reflecting electrode 17.

[0015] For example, aluminum-containing vapor is supplied from the vaporizer 1 into the plasma generation chamber 14. In the plasma generation chamber 14, plasma is generated based on the aluminum-containing vapor. An ion beam IB containing aluminum ions is extracted by an extraction electrode E through an ion extraction opening 23 of the plasma generation chamber 14. Although FIG. 1 shows two circular extraction electrodes E centered on a hole through which the ion beam IB passes, the number and shape of the extraction electrodes E are merely examples, and the number and shape of the extraction electrodes E may be changed from the illustrated configuration.

[0016] In some embodiments, the number of extraction electrodes may be more or less than 2. In general, the number of extraction electrodes may vary depending on the configuration of the ion source.

[0017] The vaporizer 1 includes a crucible 2. The crucible 2 in FIG. 1 is a cylindrical member that is long in one direction. For example, the central axis of the crucible 2 may extend along the longitudinal direction of the crucible 2 (for example, the Z direction in FIG. 1). One longitudinal end of the crucible 2 is provided with an outlet 2b for supplying aluminum-containing vapor and reactive gas to the plasma generation chamber 14. The other longitudinal end of the crucible 2 is provided with an inlet 2a for supplying a reactive gas such as a chlorine-containing gas into the crucible 2. A portion of the wall surface that forms the internal space of the crucible 2 may be formed by a first nozzle 3 attached to the outlet 2b.

[0018] In one embodiment, the chlorine-containing gas may be, for example, chlorine gas (Cl) or hydrogen chloride gas (HCl). The gas may also be an isotopically enriched gas. Furthermore, the gas may be a mixed gas in which the chlorine-containing gas is mixed with a diluent gas, such as a noble gas or hydrogen gas. The first nozzle 3 may be detachably attached to the crucible 2. Various methods (e.g., fitting and / or screwing) can be used to attach the first nozzle 3 to the crucible 2. In the embodiment shown in FIG. 1, the crucible 2 and the second nozzle 4 for supplying a reactive gas into the crucible 2 are integrally formed.

[0019] The first nozzle 3 and the second nozzle 4 are each an elongated cylindrical member. In some embodiments, the first nozzle 3, the second nozzle 4, and the crucible 2 are made of carbon. However, carbon is merely an example, and other materials may be used in some embodiments.

[0020] In FIG. 1, arrow J indicates the flow of reactive gas supplied to crucible 2. The reactive gas flows from gas supply source 11 through valve 12, second nozzle 4, crucible 2, and first nozzle 3, before entering plasma generation chamber 14. The reactive gas reacts with solid material 7 contained in crucible 2 and heated to a high temperature. In some embodiments, solid material 7 may be an aluminum-containing solid material. The reaction between this solid material 7 and the reactive gas generates a reaction product, such as aluminum chloride (AlCl). The generated reaction product vaporizes in crucible 2 to generate aluminum-containing vapor containing aluminum particles. The aluminum-containing vapor and reactive gas are supplied from crucible 2 through first nozzle 3 to plasma generation chamber 14.

[0021] In some embodiments, solid material 7 may be pure aluminum having a purity of 99.90% or greater. Pure aluminum increases the proportion of aluminum in the vapor compared to other materials. As a result, the ion beam current of the ion beam containing aluminum ions extracted from the ion source IS increases. However, solid material 7 is not limited to pure aluminum. In some embodiments, aluminum nitride, aluminum oxide, or other aluminum-containing solid materials may be used. In some embodiments, solid material 7 may be a metallic element other than aluminum.

[0022] 1, the reactive gas may be supplied to the second nozzle 4 via a mounting member 9 fitted into the second nozzle 4. For example, the reactive gas may be supplied from a gas supply source 11 that supplies the reactive gas. For example, the valve 12 may be a mass flow controller, and may be connected to a pipe 13 that connects the gas supply source 11 and the mounting member 9 to control the flow rate of the reactive gas. However, as long as the reactive gas can be supplied to the mounting member 9, the specific configuration for supplying the gas is not limited to the configuration shown in the figure.

[0023] To increase the production and vaporization of reaction products and to prevent clogging of the first nozzle 3 and the second nozzle 4, the temperature of the crucible 2 may be set to a temperature equal to or higher than the melting point of the solid material 7.

[0024] In some embodiments, the solid material 7 may be in the form of a powder, pellet, or block, and may be, for example, an aluminum-containing material, including but not limited to, pure aluminum, aluminum nitride, aluminum oxide, or other powders, depending on the type of metal ion species to be generated.

[0025] In some embodiments, the plasma generation chamber 14 can have gas ports 22 for accepting various gases instead of steam.

[0026] An end 3a of the first nozzle 3 opposite to the end attached to the crucible 2 is disposed outside the plasma generation chamber 14. The outside of the plasma generation chamber 14 mentioned here refers to the external region separated by the wall surface from the inner region where plasma is generated in the plasma generation chamber 14. The plasma generation chamber 14 has a protruding portion P that protrudes into the plasma generation chamber 14. A space R that receives steam is formed inside the protruding portion P. For example, the space R is also called a recess. The end portion 3a of the first nozzle 3 is spaced from the tip surface DS of the protruding portion P, and a gap G is formed between them. In addition, a gap is also formed between the side surface of the first nozzle 3 and the inner surface of the protruding portion P.

[0027] Fig. 2 is an enlarged view of region A in Fig. 1. For simplicity of illustration, Fig. 2 does not show the second heat shielding plate 6b, the crucible 2, and the like in Fig. 1. As shown in Fig. 2, the end 3a of the first nozzle 3 is disposed in a space R formed inside the protrusion P. The wall surface of the plasma generation chamber 14 that forms the protrusion P has at least one opening H that connects the inside and outside of the plasma generation chamber 14.

[0028] The aluminum-containing vapor flows into the space R from the end 3a of the first nozzle 3, passes through the opening H, and is supplied into the plasma generation chamber .

[0029] By locating the end 3a of the first nozzle 3 outside the plasma generation chamber 14, it is possible to prevent the end 3a from being eroded by high-temperature plasma. With this configuration, it becomes possible to continuously supply vapor from the vaporizer 1 to the plasma generation chamber 14 regardless of the operating state of the ion source IS.

[0030] Referring again to FIG. 1 , a heater 5 is wrapped around the crucible 2. The solid material 7 is heated to a high temperature by the heater 5 and reacts with the reactive gas to produce aluminum-containing vapor. In some embodiments, the heater 5 may be a coil heater. However, embodiments are not limited thereto, and in some embodiments, the heater 5 may have a different configuration, such as a plate or a filament. Additionally, a first heat shielding plate 6 a is disposed around the heater 5 to block heat radiation from the heater 5. On the other hand, it is not essential to provide the heater 5. The reaction product may be vaporized using the reaction heat generated during the chemical reaction between the reactive gas and the solid material 7. Alternatively, the vaporization using the reaction heat may be the main method, and the heater 5 may be used as an auxiliary method to promote the vaporization of the reaction product.

[0031] The temperature of the plasma generation chamber 14 at least partially affects the temperature inside the crucible 2. Due to heat transfer from the plasma generation chamber 14, the crucible 2 has a temperature distribution in the longitudinal direction.

[0032] In order to improve the temperature distribution in the crucible 2, the ion source IS may include a second heat shielding plate 6b shown in Fig. 1. The second heat shielding plate 6b is provided between the crucible 2 and a side wall of the plasma generation chamber 14 facing the crucible 2. The second heat shielding plate 6b may extend radially outward from the first nozzle 3 in parallel with the side wall of the plasma generation chamber 14. The second heat shielding plate 6b is fixed to the plasma generation chamber 14 by, for example, screws or the like.

[0033] The second nozzle 4 may have a large diameter portion 4a. A flange 8 is provided for attaching the vaporizer 1 to the ion source flange 18. A coil spring 10 is provided between the flange 8 and the large diameter portion 4a of the second nozzle 4. The coil spring 10 presses the vaporizer 1 against the side wall of the plasma generation chamber 14 to prevent aluminum-containing vapor and reactive gas from leaking out from between the first nozzle 3 and the plasma generation chamber 14. One or more gaskets (not shown) may be provided between the vaporizer 1 and the side wall of the plasma generation chamber 14 to prevent gas leakage between the first nozzle 3 and the plasma generation chamber 14. Furthermore, one or more gaskets (not shown) may be provided between the vaporizer 1 and the second heat shielding plate 6b to prevent gas leakage between the vaporizer 1 and the second heat shielding plate 6b.

[0034] A damper, such as a snap ring-shaped spring clip, may be attached to the first nozzle 3 to prevent excessive pressure due to the elastic force of the coil spring 10. A damper, such as a spring clip, may be provided between the large-diameter portion 4a of the second nozzle 4 and the inner wall of the first heat shield plate 6a to prevent excessive pressure due to the elastic force of the coil spring 10. In some embodiments, one or all of a gasket, a snap ring, and a spring clip may be provided. However, the gasket, snap ring, and spring clip are merely examples, and different or additional structures may be used to prevent excessive pressure. The ion source flange 18 indirectly supports the plasma generation chamber 14 and other components around the plasma generation chamber 14, such as the filament 16 and the cathode 15, via support parts (not shown).

[0035] The dimensions of the solid material 7 may be smaller than the interior space of the crucible 2. For example, in some embodiments, the upper end of the aluminum-containing solid material 7 may be coincident with the lower end of the outlet 2b or may be lower than the lower end of the outlet 2b. On the other hand, the dimensions of the solid material 7 may be set to be the same as the size of the internal space of the crucible 2. In this case, the solid material 7 is formed with pores for allowing the reactive gas to pass through.

[0036] In the above embodiment, an indirectly heated ion source is used, however, other types of ion sources such as a Bernas type ion source, a high frequency inductively coupled plasma type ion source, or a bucket type ion source may be used instead of the indirectly heated ion source.

[0037] The vaporizer 1 may include an insulating member 21 provided to surround the first nozzle 3 that supplies aluminum-containing vapor to the plasma generation chamber 14. Alternatively, the second heat shielding plate 6b may be omitted, and the vaporizer 1 may include only the insulating member 21. The insulating member 21 may be made of, for example, alumina (Al2O3). The insulating member 21 may be made of boron nitride (BN). However, the material of the insulating member 21 is not limited to these, and other materials having thermal insulation properties may be used.

[0038] The insulating member 21 prevents heat from the plasma generation chamber 14 from heating the first nozzle 3 and the end of the crucible 2 on the plasma generation chamber 14 side.

[0039] FIG. 3 is a perspective view of the wall surface (second wall 14b described later) of the plasma generation chamber 14 that constitutes the protrusion P shown in FIG. 1. The protrusion P is a cylindrical portion having a tip surface DS on the Z-direction side. Two openings H for supplying steam into the plasma generation chamber 14 are formed in the radial direction of the protrusion P. For example, the two openings H may be formed on both sides of the protrusion P in the X-direction of FIG. 3. Note that only one opening H is visible in FIG. 3 due to the angle of the perspective view.

[0040] The number of openings H is not limited to two, and may be one, or three or more. Furthermore, the positions on the protrusion P where the openings H are formed are not limited to the locations illustrated in Figures 1 to 3. For example, two openings H may be formed opposite each other in the Y direction.

[0041] Fig. 4 is an XY plan view of the protrusion P shown in Fig. 3 when viewed from the front. As shown in Fig. 4, the opening H may be formed by cutting out a part of the side surface of the protrusion P linearly along the Y direction.

[0042] Fig. 5 is a cross-sectional view of a simplified ion source IS shown in Fig. 1. Fig. 6 is a cross-sectional view of the ion source IS of Fig. 5 as viewed from another plane. The configuration relating to the supply of vapor from the vaporizer 1 to the plasma generation chamber 14 will be described in detail with reference to Figs. 5 and 6.

[0043] The plasma generation chamber 14 has a first wall 14a and a second wall 14b facing each other. In the embodiment shown in Figures 5 and 6, the first wall 14a has an ion extraction opening 23 for extracting the ion beam IB.

[0044] The second wall 14b has three portions. The second wall 14b has a first portion 14b1 and a second portion 14b2 at different positions in the opposing direction of the first wall 14a and the second wall 14b (a direction parallel to the Z direction in the figure). The second wall 14b also has a third portion 14b3 between the first portion 14b1 and the second portion 14b2. As shown in FIG. 5, the second portion 14b2 and the third portion 14b3 define a space R (recess) in the Z direction in the second wall 14b.

[0045] The second portion 14b2 and the third portion 14b3 correspond to a protruding portion P where a part of the plasma generation chamber 14 protrudes inward of the plasma generation chamber 14. In the embodiment shown in Fig. 5, an opening H for supplying steam is formed in the wall of the plasma generation chamber 14 that constitutes the third portion 14b3.

[0046] The protrusion P may have a plurality of openings H formed in its circumferential direction. Also, the protrusion P may have a plurality of openings H formed in its axial direction. Furthermore, the protrusion P may have a plurality of openings H formed in both the circumferential direction and the axial direction.

[0047] The positions of the openings H provided in the circumferential direction of the protrusion P may be different from each other in the Z direction. Also, the positions of the openings H provided in the axial direction of the protrusion P may be different from each other in the X direction or the Y direction.

[0048] The opening H may be formed not only on the side surface of the protrusion P but also on the tip surface DS of the protrusion P. Of course, the opening H may be formed on only one of the side surface of the protrusion P and the tip surface DS of the protrusion P.

[0049] The position where the opening H is formed is not particularly limited, but in consideration of the plasma generation efficiency in the plasma generation chamber 14, it is advantageous to form the opening H at a position that does not face the ion extraction opening 23 for the ion beam.

[0050] With the above configuration, it is possible to prevent the vapor supplied into the plasma generation chamber 14 through the opening H from being emitted to the outside of the plasma generation chamber 14 through the ion beam ion extraction opening 23 before being converted into plasma in the plasma generation chamber 14. This makes it possible to prevent a decrease in the plasma generation efficiency.

[0051] The shape of the opening H can be various shapes such as a rectangle, a circle, a triangle, etc. in a plan view. The opening H may be formed on the side surface of the protrusion P in a direction oblique to the radial and axial directions of the protrusion P.

[0052] The protrusion P does not necessarily have to be disposed at the center of the wall (e.g., the second wall 14b) of the plasma generation chamber 14, and may be disposed at a position eccentric to the wall end from the center. For example, the protrusion P may be disposed between the wall end of the second wall 14b and the center of the second wall 14b in any of the X, Y, and Z directions.

[0053] 5 and 6, the third portion 14b3 is cylindrical, but may have other shapes. Specifically, the protrusion P is cylindrical or rectangular, with the distal end surface DS closed by the second portion 14b2, and the proximal end surface opposite the distal end surface DS in the Z direction open so that the end 3a of the first nozzle 3 can be inserted and accommodated.

[0054] In the opposing direction of the first wall 14a and the second wall 14b, the position where the opening H is formed is closer to the first wall 14a than the position where the end 3a of the first nozzle 3 is disposed. Due to this relationship, the steam flowing in from the end 3a of the first nozzle 3 smoothly flows into the plasma generation chamber 14 through the opening H.

[0055] However, this is merely one embodiment, and the positional relationship between the end 3a of the first nozzle 3 and the location where the opening H is formed may be reversed from the configuration shown in Figures 5 and 6. In other words, in the opposing direction between the first wall 14a and the second wall 14b, the position where the end 3a of the first nozzle 3 is disposed may be closer to the first wall 14a than the position where the opening H is formed.

[0056] 1 to 4, the shape of the protrusion P may be a cone or a triangular pyramid with the top cut off and the cut-off portion closed with a lid, as shown in FIG. 7. The shape of the protrusion P may be a hemisphere, as shown in FIG. 8. In the configuration of FIG. 8, the second portion 14b2 may be the apex of a hemisphere, or the entire area of ​​the second portion 14b2 and the third portion 14b3 may be formed by a curved surface. On the other hand, as shown in FIG. 7, the top of the hemisphere of FIG. 8 (the end portion on the first wall 14a side) may be cut out and the cut-out portion may be closed to make the second portion 14b2 flat.

[0057] 9, the protrusion P may be configured to widen toward the inside of the plasma generation chamber 14. That is, the diameter of the protrusion P increases as it moves away from the second wall 14b. Also, as shown in FIG. 10, the shape of the protrusion P may be asymmetric in the X direction.

[0058] In the ion source IS shown in FIGS. 1 to 10, the ion extraction opening 23 is formed in the first wall 14a of the plasma generation chamber 14. However, this configuration is merely an example. For example, as shown in FIG. 11, the ion extraction opening 23 may be formed in the wall surface of the plasma generation chamber 14 in the X direction. FIG. 12 is a cross-sectional view of the ion source IS shown in FIG. 11 when viewed from another plane.

[0059] 11, an aperture H is formed in the wall on which the ion extraction aperture 23 is formed. However, the aperture H and the ion extraction aperture 23 do not face each other in the direction in which steam is released from the aperture H. That is, the position of the ion extraction aperture 23 in the Z direction does not coincide with the position of the aperture H in the Z direction, and they are offset from each other. In the configuration shown in FIG. 11, plasma generation efficiency is improved compared to a configuration in which the aperture H and the ion extraction aperture 23 are directly opposite each other in the direction in which steam is released from the aperture H.

[0060] The ion source IS shown in FIGS. 1 to 11 has a configuration in which vapor is emitted from one vaporizer 1 into the plasma generation chamber 14. However, the number of vaporizers 1 is not limited to one, and multiple vaporizers 1 may be used to supply vapor to the plasma generation chamber 14. In this case, the types of vapor supplied from each vaporizer to the plasma generation chamber 14 may be the same or different.

[0061] The configuration of the vaporizer 1 is not limited to the configuration shown in Fig. 1. For example, the vaporizer 1 may be of a type that does not introduce a reactive gas into the crucible 2. In such a vaporizer, the solid material 7 placed in the crucible 2 is heated to directly vaporize the solid material 7, and the vapor is supplied to the plasma generation chamber 14. Although an aluminum-containing material has been used as the solid material 7 in the above description, an appropriate solid material may be placed in the crucible 2 depending on the type of ions extracted from the ion source IS.

[0062] In the above embodiment, a structure has been described in which the vaporizer 1 is elastically biased against the plasma generation chamber 14 to seal the gap between the vaporizer 1 and the plasma generation chamber 14. The sealing structure is not limited to this configuration. For example, the insulating member 21 shown in FIG. 1 may be fixed to the protrusion P by screwing or fitting it to seal the gap between the vaporizer 1 and the plasma generation chamber 14. Similarly, instead of the insulating member 21, the first nozzle 3 may be a double-cylinder, with the outer cylinder longer than the inner cylinder and fixed to the plasma generation chamber 14. Alternatively, the vaporizer 1 may be pressed against the plasma generation chamber 14 using an elastic member to seal the gap between the vaporizer 1 and the plasma generation chamber 14.

[0063] 1, if the material of the plasma generation chamber 14 is molybdenum, a reaction between aluminum and molybdenum may produce an aluminum alloy with a high melting point in the opening H, which may clog the opening H. To prevent such clogging, the protrusion P or the entire plasma generation chamber 14 may be made of a tungsten material.

[0064] The first portion 14b1, the second portion 14b2, and the third portion 14b3 of the second wall 14b of the plasma generation chamber 14 may be formed of the same material, or each portion may be formed of a different material. For example, the second portion 14b2 and the third portion 14b3 may be formed of a single material, and the first portion 14b1 may be assembled to the single material consisting of the second portion 14b2 and the third portion 14b3.

[0065] The number of openings H is not limited, and may be one as shown in Fig. 13. Alternatively, it may be three or more as shown in Fig. 14. The openings H may be formed in the second portion 14b2 as shown in Fig. 15. Alternatively, the openings H may be formed in both the second portion 14b2 and the third portion 14b3 as shown in Fig. 16.

[0066] Furthermore, the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications are possible without departing from the spirit of the present invention. [Explanation of symbols]

[0067] 1. Vaporizer 2 Crucible 3 nozzles 3a End of nozzle 14 Plasma generation chamber 14a First Wall 14b Second wall 14b1 Part 1 14b2 2nd part 14b3 3rd part 23 Ion extraction aperture IS ion source H opening DS tip surface R space (recess) P protrusion

Claims

1. a vaporizer having a nozzle; a plasma generation chamber to which vapor is supplied from the vaporizer through the nozzle, the nozzle is disposed outside the plasma generation chamber, the plasma generation chamber has a first wall and a second wall facing each other, the second wall has a first portion and a second portion at different positions in a direction in which the first wall and the second wall oppose each other, and a third portion between the first portion and the second portion; an ion source, wherein the second portion or the third portion has an opening for supplying the vapor from the vaporizer to the plasma generation chamber.

2. the nozzle has an end for emitting the steam; The second portion and the third portion form a space outside the plasma generation chamber, The ion source of claim 1 , wherein the end of the nozzle is disposed in the space.

3. 3. The ion source according to claim 2, wherein the end of the nozzle is disposed closer to the second wall than the opening in the opposing direction of the first wall and the second wall.

4. a vaporizer having a nozzle and configured to generate vapor; a plasma generation chamber that receives the vapor from the nozzle, the plasma generation chamber has a first wall and a second wall facing the first wall, the second wall has a protrusion protruding toward the first wall, the nozzle is disposed on the protrusion outside the plasma generation chamber; The protrusion has an opening through which the vapor is supplied into the plasma generation chamber.

5. the nozzle has an end; The ion source of claim 4 , wherein the protrusion has a space in which the end of the nozzle is disposed.

6. the protruding portion has a tip end surface on the first wall side in a direction in which the first wall and the second wall face each other, The ion source of claim 5 , wherein the opening is formed in a wall of the protrusion between the end of the nozzle and the tip surface of the protrusion.

7. a vaporizer having a nozzle; a plasma generation chamber for generating plasma, The plasma generation chamber comprises: a first wall having an ion extraction aperture; a second wall that faces the first wall in the axial direction of the nozzle, the second wall including a protruding portion that protrudes into the plasma generation chamber and has a recess in which an end of the nozzle is disposed, The ion source, wherein the protrusion includes an opening in fluid communication with the interior of the plasma generation chamber.

8. The ion source of claim 7 , wherein the protrusion has a cylindrical wall that defines the recess and a tip surface.

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