Crucible design for liquid metal in an ion source

Abstract

A crucible is disclosed that exploits the observation that molten metal tends to flow toward the hottest region. The crucible includes an interior in which a dopant material may be disposed. The crucible has a passageway leading from the interior toward an aperture, with a continuous increase in temperature along the passageway. The aperture may be disposed within or near the interior of an arc chamber of an ion source. Liquid metal flows along the passageway toward the arc chamber, where it is vaporized and then ionized. By controlling the flow rate of the passageway, spillage may be reduced. In another embodiment, an inverted crucible is disclosed. The inverted crucible includes a closed end in communication with the interior of the ion source, such that the closed end is the hottest region of the crucible. Openings are disposed in different walls to allow vapor to exit the crucible.

Description

Technical Field

[0001] This application claims priority to U.S. Patent Application No. 17 / 353,171, filed on June 21, 2021, the entire disclosure of which is incorporated herein by reference, and the disclosure of which is incorporated herein by reference in its entirety.

[0002] Embodiments of the present disclosure relate to the design of a crucible, and more particularly, to a crucible for use with a metal in an ion source.

Background Art

[0003] Various types of ion sources can be used to create ions for use in semiconductor processing equipment. For example, an indirectly heated cathode (IHC) ion source operates by supplying current to a filament disposed behind a cathode. The filament emits thermionic electrons, which are accelerated towards the cathode, heating the cathode, whereby the cathode emits electrons into the arc chamber of the ion source. The cathode is disposed at one end of the arc chamber. Generally, a repeller is disposed on the end of the arc chamber opposite the cathode. The cathode and the repeller are biased to repel electrons, whereby the electrons can be directed back towards the center of the arc chamber. In some embodiments, a magnetic field is used to further confine the electrons within the arc chamber.

[0004] In some embodiments, it may be desirable to utilize a feedstock that is in solid form as the dopant species. For example, the solid feedstock can serve as a sputter target. Ions strike the solid feedstock, thereby releasing neutral particles of the feedstock, and the neutral particles are then ionized in the plasma, energized, and can be used for deposition or implantation. However, there are problems associated with using a solid feedstock. For example, in the high temperature environment of an IHC ion source, liquid metal flows into and accumulates in the arc chamber, so the metal sputter target melts, drips, and generally degrades and is prone to breaking the arc chamber. Therefore, since the ceramics containing the dopant have a higher melting temperature, such ceramics are generally used as solid dopant materials. However, generally, the beam current of the dopant generated by these ceramic materials is less. A significant increase in dopant beam current could be achieved if the metal sputter target could maintain its shape without dripping or deforming during melting.

[0005] Therefore, an advanced crucible design that can be used within the ion source without these limitations would be beneficial. SUMMARY OF THE INVENTION

[0006] A crucible is disclosed that utilizes the observation that molten metal tends to flow towards the hottest region. The crucible includes an interior in which a dopant material can be disposed. The crucible has a path that communicates from the interior towards a crucible aperture, and the temperature continuously increases along the path. The crucible aperture can be disposed within or near the interior of the arc chamber of the ion source. Liquid metal flows along the path towards the arc chamber, where the liquid metal is evaporated and then ionized. By controlling the flow rate of the path, spillage can be reduced. In another embodiment, an inverted crucible is disclosed. The inverted crucible has a closed end that communicates with the interior of the ion source, such that the closed end becomes the hottest region of the crucible. A crucible opening is disposed in a different wall at a lower temperature to allow vapor to exit the crucible.

[0007] According to one embodiment, an ion source for generating an ion beam containing metal is disclosed. The ion source includes an arc chamber having an interior for containing plasma and an extraction aperture for extracting the ion beam, and a crucible having a crucible aperture that communicates with the interior of the arc chamber. The crucible includes a path extending from the interior of the crucible towards the interior of the arc chamber, and the temperature continuously increases along the path. In some embodiments, the path extends into the interior of the arc chamber. In some embodiments, the metal includes aluminum, gallium, lanthanum, or indium. In some embodiments, the path includes a wicking rod having a first end disposed within the interior of the crucible and a tip proximate to the crucible aperture. In some embodiments, the path includes a hollow tube.

[0008] According to another embodiment, an ion source for generating an ion beam containing metal is disclosed. The ion source includes an arc chamber having an interior for containing plasma and an extraction aperture for extracting the ion beam, a crucible having a crucible aperture communicating with the interior of the arc chamber, a wicking rod disposed within the interior of the crucible and having a first end and a tip proximate to the crucible aperture. In some embodiments, the tip extends beyond the crucible aperture and enters into the interior of the arc chamber. In some embodiments, the first end of the wicking rod is fixed to the rear wall of the crucible. In some embodiments, the ion source includes a porous material disposed within the interior of the crucible, in front of the crucible aperture, the porous material having an opening through which the wicking rod passes. In some embodiments, the wicking rod includes a straight solid cylinder. In some embodiments, the wicking rod includes at least one bent portion. In some embodiments, the wicking rod includes at least one upwardly inclined portion, and due to the inclination of the at least one upwardly inclined portion, liquid metal can flow from the interior of the crucible towards the tip. In some embodiments, the crucible includes a front wall including the crucible aperture, and the wicking rod rests on the inner surface of the crucible, is inclined upwardly, and rests on the front wall. In some embodiments, the first end of the wicking rod is not fixed to the inner surface of the crucible. In some embodiments, the wicking rod rests on the inner surface of the crucible, is inclined upwardly, and rests on the porous material.

[0009] According to another embodiment, an ion source for generating an ion beam containing metal is disclosed. The ion source includes an arc chamber having an interior for containing a plasma and an extraction aperture for extracting the ion beam, and a crucible having a closed end communicating with the interior of the arc chamber. The crucible has a crucible opening in a wall different from the closed end, and vapor of the metal exits through the crucible opening and enters the arc chamber. In some embodiments, the crucible opening is disposed in a wall having a lower temperature than the closed end. In some embodiments, the crucible opening is disposed in a wall opposite to the closed end. In some embodiments, the ion source includes a channel communicating with the crucible opening and the interior of the arc chamber, whereby the vapor reaches the arc chamber through the channel. In some embodiments, the ion source includes a porous material disposed within the interior of the crucible proximate to the crucible opening, whereby the vapor passes through the porous material before exiting through the crucible opening.

[0010] For a better understanding of the present disclosure, reference is made to the accompanying drawings which are incorporated herein by reference.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2A

Figure 2B

Figure 2C

Figure 2D

Figure 3

Mode for Carrying Out the Invention

[0012] As described above, metal sputtering targets can be problematic when the temperature within the arc chamber or other processing chamber exceeds the melting point of the metal. In such cases, the metal sputtering target can become molten and drip into the arc chamber, which can, in some cases, cause damage and shorten the life of the arc chamber.

[0013] Furthermore, testing has unexpectedly shown that liquid metal has a tendency to move towards regions of maximum temperature. In this way, in some embodiments, the liquid metal can actually advance against gravity towards hotter regions.

[0014] This behavior makes it difficult to effectively contain the liquid metal while exposing it to plasma so that the liquid metal can be ionized.

[0015] Accordingly, in some embodiments, crucibles can be designed that take this behavior into account. One such crucible is shown in FIG. 1 with an indirectly heated cathode (IHC) ion source. Although the IHC ion source will be described, it should be understood that the crucible can be used with Bernas ion sources, plasma chambers, or other ion sources.

[0016] FIG. 1 shows an ion source that utilizes this crucible. The IHC ion source 10 includes an arc chamber 100 having two opposing ends and a wall 101 connecting these ends. The wall 101 of the arc chamber 100 can be constructed from a conductive material and can be in electrical communication with each other. In some embodiments, a liner can be disposed proximate to one or more of the walls 101. The liner can cover the entirety of one or more of the walls 101 so that one or more of the walls 101 are not exposed to the harsh environment within the arc chamber 100. A cathode 110 is disposed in the arc chamber 100 at a first end 104 of the arc chamber 100. A filament 160 is disposed behind the cathode 110. The filament 160 is in communication with a filament power supply 165. The filament power supply 165 is configured to pass a current through the filament 160 so that the filament 160 emits thermionic electrons. A cathode bias power supply 115 biases the filament 160 negatively with respect to the cathode 110, and thus, when the thermionic electrons strike the back surface of the cathode 110, those thermionic electrons are accelerated from the filament 160 toward the cathode 110 and heat the cathode 110. The cathode bias power supply 115 can bias the filament 160 so that the filament 160 has a voltage that is negative relative to the voltage of the cathode 110, for example, between 200V and 1500V. The cathode 110 then emits thermionic electrons into the arc chamber 100 on its front surface.

[0017] In this way, the filament power supply 165 supplies current to the filament 160. The cathode bias power supply 115 biases the filament 160 so that the filament 160 is negative with respect to the cathode 110, whereby electrons are attracted from the filament 160 toward the cathode 110. In some embodiments, the cathode 110 can be biased with respect to the arc chamber 100, such as by the arc power supply 111. In other embodiments, the cathode 110 can be electrically connected to the arc chamber 100 such that it has the same voltage as the wall 101 of the arc chamber 100. In these embodiments, the arc power supply 111 may not be employed, and the cathode 110 can be electrically connected to the wall 101 of the arc chamber 100. In some embodiments, the arc chamber 100 is connected to electrical ground.

[0018] On the second end 105, which is opposite to the first end 104, a repeller 120 may be disposed. The repeller 120 can be biased with respect to the arc chamber 100 by a repeller bias power supply 123. In other embodiments, the repeller 120 can be electrically connected to the arc chamber 100 such that it has the same voltage as the wall 101 of the arc chamber 100. In these embodiments, the repeller bias power supply 123 may not be employed, and the repeller 120 can be electrically connected to the wall 101 of the arc chamber 100. In yet other embodiments, the repeller 120 is not employed.

[0019] The cathode 110 and the repeller 120 are each manufactured from a conductive material, such as metal or graphite.

[0020] In some embodiments, a magnetic field is generated in the arc chamber 100. This magnetic field confines electrons along one direction. The magnetic field generally travels parallel to the wall 101 from the first end 104 to the second end 105. For example, the electrons can be confined in a row (i.e., the y-direction) parallel to the direction from the cathode 110 to the repeller 120. Thus, the electrons move in the y-direction without being subject to an electromagnetic force. However, the movement of electrons in other directions can be subject to an electromagnetic force.

[0021] An extraction aperture 140 can be disposed on one surface of the arc chamber 100, called the extraction plate 103. In FIG. 1, the extraction aperture 140 is disposed on a surface parallel to the Y-Z plane (perpendicular to the page). Further, the IHC ion source 10 also includes a gas inlet 106 through which the source gas to be ionized can be introduced into the arc chamber 100.

[0022] The controller 180 can communicate with these power supplies such that the voltage or current supplied by one or more of the power supplies can be changed. The controller 180 can include a processing unit, such as a microcontroller, a personal computer, a dedicated controller, or another suitable processing unit. The controller 180 can also include a non-transitory storage element, such as a semiconductor memory, a magnetic memory, or another suitable memory. This non-transitory storage element can include instructions and other data that enable the controller 180 to perform the functions described herein.

[0023] The IHC ion source 10 also includes a crucible 200. The crucible 200 can protrude into the arc chamber 100 through one of the walls 101. This can be the wall 101 on the opposite side of the extraction aperture 140 as shown in FIG. 1, or it can be a different wall 101.

[0024] The crucible 200 includes an outer wall 210. These outer walls 210 can be manufactured from a material that is relatively unaffected by the plasma generated in the IHC ion source 10. Further, the material used for the outer walls 210 can be compatible with the thermal environment and the liquid metal. For example, in one embodiment, the outer wall 210 can be graphite. These outer walls 210 define a cavity 212 in which the metal to be ionized is disposed. In some embodiments, the cavity 212 can have an inner diameter of 1 inch or less. In some embodiments, the length of the cavity 212 can be 1 inch or more. However, other dimensions can also be utilized. The crucible can be cylindrical, can be in the form of a rectangular parallelepiped, or can have a different shape. Further, the front wall 216 of the crucible 200 includes a crucible opening 211. In this embodiment, the crucible opening 211 enables the cavity 212 to communicate directly with the interior of the IHC ion source 10. In other words, the end of the crucible having the crucible opening 211 can define a part of one of the walls 101 of the IHC ion source 10.

[0025] A wicking rod 220 is disposed within the cavity 212. In some embodiments, the wicking rod 220 can be fixed to the rear wall 213 of the crucible 200, which faces the wall including the crucible opening 211. The wicking rod 220 can also not be fixed to the crucible 200 and can be held in a predetermined position by gravity. The wicking rod 220 can be manufactured from graphite or tungsten. Other materials such as carbides and nitrides can also be used. In the embodiment shown in FIG. 1, the wicking rod 220 has a straight solid cylindrical structure. However, in other embodiments described below, the wicking rod 220 can have a different shape. The length of the wicking rod 220 can be longer than the depth of the cavity 212 such that the tip 221 of the wicking rod 220 extends beyond the crucible 200 and can enter the IHC ion source 10. The diameter of the wicking rod 220 can be adjusted based on the application and the desired flow rate of the liquid metal. In some embodiments, as the diameter increases, the flow rate can increase.

[0026] A dopant material 230, such as a metal, is disposed in the cavity 212. In one embodiment, the dopant material 230 is a solid metal such as aluminum, gallium, lanthanum, or indium. This solid material can be extruded into the form of a wire and wound onto the wicking rod 220. In other embodiments, the solid material can be in the form of beads, or a hollow cylinder attached around the wicking rod 220.

[0027] During operation, the filament power supply 165 passes current through the filament 160, causing the filament 160 to emit thermionic electrons. These electrons strike the back surface of the cathode 110, making the cathode 110 more positive than the filament 160, thereby heating the cathode 110 and enabling the cathode 110 to emit electrons into the arc chamber 100. These electrons collide with the molecules of the source gas supplied into the arc chamber 100 through the gas inlet 106. The source gas can be a carrier gas such as argon, or an etching gas such as BF3 or other halogen species. A combination of electrons from the cathode 110, the source gas, and a positive potential creates a plasma. In some embodiments, the electrons and positive ions can be somewhat confined by a magnetic field. In some embodiments, the plasma is confined near the center of the arc chamber 100, close to the extraction aperture 140. This plasma heats the tip 221 of the wicking rod 220, which helps to melt the dopant material 230 in the cavity 212. Since the tip 221 of the wicking rod 220 reaches the highest temperature, the dopant material 230 tends to flow towards the tip 221 after melting. Since the tip 221 is disposed in the IHC ion source 10, plasma-assisted chemical etching or sputtering converts the dopant material 230 into the gas phase and causes ionization. The ionized feed material is then extracted through the extraction aperture 140 and can be used to generate an ion beam.

[0028] In some embodiments, the thermal conductivity between the wicking rod 220 and the rear wall 213 can be increased. For example, the cross-sectional area of the wicking rod 220 can be smaller near the rear wall 213. This is done to ensure that the tip 221 is the hottest point and that the dopant material 230 flows out through the crucible opening 211.

[0029] FIG. 1 shows an example of a crucible, but other variations are possible. For example, as shown in FIG. 2A, a porous material 240 can be included in the cavity 212 to accommodate the dopant material 230. The porous material 240 can be dimensioned such that it has the same outer dimensions as the inner dimensions of the cavity 212. Further, the porous material 240 can have pores 241 therethrough. The porous material 240 can be arranged such that it is disposed between the dopant material 230 and the crucible opening 211. The wicking rod 220 can pass through the pores 241 in the porous material 240. In this way, the porous material 240 holds the dopant material 230 within the cavity 212 while allowing the molten material to flow along the wicking rod 220 towards the tip 221. Similar to FIG. 1, the tip 221 can extend into the arc chamber 100 of the IHC ion source 10.

[0030] Figure 2B shows a deformed form of the crucible 200 shown in Figure 2A. In this embodiment, the crucible 201 supports the wicking rod 220 at a position closer to the bottom of the crucible 201. For example, Figures 1 and 2A show the wicking rod 220 disposed at or near the center of the crucible 200 and attached to the rear wall 213. This embodiment may allow for greater utilization of the dopant material 230 disposed in the cavity 212. A porous material 240 having holes 241 is also disposed in the cavity 212. In this embodiment, the outer wall 210 may be formed such that the bottom 215 of the outer wall 210 extends outward beyond the upper portion of the outer wall 210 and includes a front wall 216, thereby creating an open receptacle 214 having a crucible opening 211 adapted to hold the molten material falling from the wicking rod 220. In some embodiments, the bottom 215 of the outer wall 210 extends beyond the wall 101 of the IHC ion source 10. The wicking rod 220 may extend into the volume defined by this open receptacle 214 and also into the volume defined by the wall 101.

[0031] Note that this figure shows the dopant material 230 configured as a wire wound around the wicking rod 220 and beads disposed on that wire. However, the dopant material 230 can take any shape or multiple shapes.

[0032] Furthermore, Figures 1, 2A - 2B show the wicking rod 220 as being parallel to the major axis of the crucible and perpendicular to the wall 101 of the IHC ion source 10. However, other deformations are possible. For example, the wicking rod 220 may be attached to the rear wall 213 near the bottom of the crucible and may be inclined upward as the wicking rod 220 moves toward the crucible opening 211. This inclination may be set to allow the liquid metal to flow upward along the wicking rod 220 toward the tip 221.

[0033] In another embodiment shown in FIG. 2C, the wicking rod 220 is not directly fixed to the outer wall 210 of the crucible 202, but rather may remain unattached within the cavity 212 of the crucible 202 and be held in a predetermined position by gravity. As a result, the tip of the wicking rod 220 is no longer thermally sunk directly to the rear wall 213, allowing the tip 221 of the wicking rod 220 to become hotter. If the crucible opening 211 of the crucible 202 is near the top of the crucible 202, this also allows the wicking rod 220 to naturally assume an upward tilt. Thus, the wicking rod 220 rests on the inner surface of the crucible 202, slopes upward through the crucible opening 211, and rests on the front wall 216. In some embodiments, the wicking rod 220 is not fixed to the inner surface. A porous material 240 having holes 241 is also disposed within the cavity 212. As described with reference to FIG. 2B, in this embodiment, the outer wall 210 may be formed such that the bottom 215 of the outer wall 210 extends outwardly beyond the top of the outer wall 210, thereby creating an open receptacle 214 having the crucible opening 211. In some embodiments, the bottom 215 of the outer wall 210 extends beyond the wall 101 of the IHC ion source 10. The wicking rod 220 extends into the volume defined by this open receptacle 214 and may rest on the front wall 216 of the crucible 202.

[0034] In another embodiment, the holes 241 in the porous material 240 may be arranged such that the wicking rod 220 is supported by the inner surface of the crucible 202 and the porous material 240 and does not contact the front wall 216.

[0035] FIG. 2C shows that the crucible 202 includes a bottom 215 that extends further than the remaining outer wall 210, but this embodiment is not limited to this embodiment. For example, the crucible shown in FIG. 2A may be used with the inclined wicking rod 220 shown in FIG. 2C, and the crucible opening 211 may be located near the top of the front wall 216 such that the wicking rod 220 slopes upward and rests on the front wall 216.

[0036] Furthermore, in another embodiment, the wicking rod 220 may be fixed to the inner surface of the crucible 202, inclined upwardly toward the crucible opening 211, and extend into the IHC ion source 10. In one embodiment, as shown in FIG. 2C, the wicking rod 220 may rest on the front wall 216. However, in other embodiments, the wicking rod 220 may be separated from the front wall 216, similar to the embodiment shown in FIG. 2A.

[0037] FIG. 2D shows another embodiment of the crucible 203. In this embodiment, the outer wall 210 may be as described with respect to FIG. 2B. However, in this embodiment, the wicking rod 260 is not a straight cylinder; rather, the wicking rod 260 may have a bend 263 therein. For example, the wicking rod 260 may be disposed near the bottom of the crucible 203 but may incline upwardly after passing through the holes 241 in the porous material 240. This upward inclination 262 allows the tip 221 of the wicking rod 220 to become hotter, thereby increasing the temperature gradient. This upward inclination 262 may be an angle that allows the liquid metal to flow upwardly toward the tip 261.

[0038] Of course, the wicking rod may take any suitable shape such that it contacts the dopant material 230 and has a tip disposed in or near the IHC ion source 10.

[0039] Furthermore, the flow rate of the liquid metal along the wicking rod can be controlled by varying one or more of the following parameters of the wicking rod: namely, diameter, length, shape, finish, material, and porosity. For example, as the diameter increases, the surface area of the wicking rod 220 becomes larger, so a higher flow rate of the liquid material can be supported. Additionally, a textured finish can reduce the flow rate of the liquid material compared to a smooth finish.

[0040] Furthermore, the cross-section of the wicking rod 220 can vary along its length. For example, a taper can be used at the tip 221 to limit the amount of liquid material that can flow in the arc chamber 100 and thus control the vaporization rate of the liquid material.

[0041] Thus, in each of these embodiments, the crucible is designed to utilize the observation that the liquid metal flows towards the hottest region and even against gravity to do so. Thus, the dopant material 230 is disposed in the cavity, and there is a path into the interior of the IHC ion source 10 in the cavity, and the temperature along the path can increase continuously such that the liquid material follows the path. Further, the path can be designed such that an amount of material can flow through the path. In other words, the flow rate through the path can be controlled. This enables better control of the ionization rate and can also reduce the likelihood of outflow.

[0042] A wicking rod can be used to achieve these goals, but other techniques can also be used to provide a path where the temperature increases continuously. For example, a hollow rod or tube can be routed such that the temperature gradient increases and the dopant material 230 progresses through the interior of the rod.

[0043] The observation that liquid metal tends to flow towards a hotter region can also be used in other ways. For example, in FIGS. 1 and 2A-2D, this observation is utilized to draw liquid metal into the IHC ion source 10, but other embodiments are possible.

[0044] FIG. 3 shows an inverted crucible 300. In this embodiment, the inverted crucible 300 is arranged such that the closed end 311 is disposed in the IHC ion source 10. The IHC ion source 10 is as described above.

[0045] In this way, since the closed end portion 311 communicates with the inside of the arc chamber 100 of the IHC ion source 10, the closed end portion 311 can be the hottest surface. Therefore, the dopant material 330 tends to flow toward the closed end portion 311. Since this closed end portion 311 does not include an opening, outflow is avoided. However, the heat from the closed end portion 311 can cause the dopant material 330 to evaporate. This vapor can then freely exit through the crucible opening 312 at the cooler end of the inverted crucible 300. The crucible opening 312 can be disposed on a wall at a lower temperature than the closed end portion 311 so that the dopant material 330 is not drawn toward the crucible opening 312. In some embodiments, as shown in FIG. 3, the crucible opening 312 is on the opposite side of the closed end portion 311. However, in other embodiments, the crucible opening 312 can be on a different wall 310, such as the upper wall. Further, a porous material 340 can be disposed in proximity to the crucible opening 312. The porous material 340 can be disposed between the crucible opening 312 and the dopant material 330 to minimize the flow of liquid material from the inverted crucible 300. Further, a channel 350 can communicate from the crucible opening 312 to the IHC ion source 10 so that vapor can flow into the arc chamber 100. In some embodiments, the channel 350 is outside the inverted crucible 300. Thus, in this embodiment, the closed end portion 311 serves to pull the liquid away from the crucible opening 312 such that vapor can exit the inverted crucible 300 but the liquid material is not drawn toward the crucible opening 312.

[0046] Although an IHC ion source is disclosed in FIG. 1, it should be understood that any of the crucibles depicted in the figure can be utilized with any ion source having an interior for containing plasma and having an extraction aperture. For example, the ion source can be a plasma chamber, a Bernas source, or another type of ion source.

[0047] The embodiments described above in this application can have many advantages. First, in this system, it is possible to use a solid metal material as a dopant material without problems associated with the prior art.

[0048] In particular, in some embodiments, a path is created from the cavity holding the dopant material to the IHC ion source 10, along which the temperature continuously increases. Since the liquid metal tends to flow towards the hottest region, the liquid material is drawn towards the IHC ion source. However, by appropriate design of this path, the flow rate of the liquid material towards the IHC ion source can be controlled, and thus the ionization rate can be controlled, and the possibility of outflow can be minimized.

[0049] In other embodiments, the cavity containing the dopant material may have one end maintained at the highest temperature so as to attract the liquid. This helps to divert the liquid from the openings at different ends of the crucible. In this way, while minimizing the possibility of the liquid exiting through the openings, the vapor can escape through the openings.

[0050] The present disclosure should not be limited in scope by the specific embodiments described herein. Indeed, in addition to those described herein, various other embodiments of the present disclosure and modifications to the present disclosure will become apparent to those skilled in the art from the above description and the accompanying drawings. Accordingly, such other embodiments and modifications are within the scope of the present disclosure. Further, although the present disclosure has been described herein in the context of specific implementations of specific embodiments for specific purposes, those skilled in the art will recognize that its usefulness is not limited thereto and that the present disclosure can be beneficially implemented in any number of environments for any number of purposes. Accordingly, the claims set forth below should be construed in view of the full scope and spirit of the present disclosure described herein.

Claims

1. An ion source for generating an ion beam containing a metal, comprising: an arc chamber having an interior for containing a plasma and an extraction aperture for extracting the ion beam; a crucible having a crucible aperture communicating with the interior of the arc chamber; and a wicking rod provided with a path extending from the interior of the crucible toward the interior of the arc chamber, along which path liquid metal moves and the temperature continuously increases, the path having a first end disposed in the interior of the crucible and a tip proximate to the crucible aperture. Ion source.

2. The ion source according to claim 1, wherein the path extends to the interior of the arc chamber.

3. The ion source according to claim 1, wherein the metal includes aluminum, gallium, lanthanum, or indium.

4. An ion source for generating an ion beam containing a metal, comprising: an arc chamber having an interior for containing a plasma and an extraction aperture for extracting the ion beam; a crucible having a crucible aperture communicating with the interior of the arc chamber; and a wicking rod having a first end disposed in the interior of the crucible and a tip proximate to the crucible aperture. Ion source.

5. The ion source according to claim 4, wherein the tip extends beyond the crucible aperture and into the interior of the arc chamber.

6. The ion source according to claim 4, wherein the first end of the wicking rod is fixed to the rear wall of the crucible.

7. The ion source according to claim 4, further comprising a porous material disposed in the interior of the crucible in front of the crucible aperture, the porous material having an opening through which the wicking rod passes.

8. The ion source according to claim 4, wherein the wicking rod includes a straight solid cylinder.

9. The ion source according to claim 4, wherein the wicking rod includes at least one bent portion.

10. The ion source according to claim 4, wherein the wicking rod includes at least one upwardly inclined portion, and due to the inclination of the at least one upwardly inclined portion, liquid metal can flow from the interior of the crucible toward the tip.

11. The crucible includes a front wall including the crucible opening, and the wicking rod is placed on the inner surface of the crucible, inclined upward, and placed on the front wall. The ion source according to claim 4.

12. The ion source according to claim 11, wherein the first end of the wicking rod is not fixed to the inner surface of the crucible.

13. The wicking rod is placed on the inner surface of the crucible, inclined upward, and placed on the porous material. The ion source according to claim 7.

14. An ion source for generating an ion beam containing a metal, An arc chamber having an interior for containing plasma and an extraction opening for extracting the ion beam, A crucible having a closed end communicating with the interior of the arc chamber, the crucible having a crucible opening in a wall different from the closed end, and the vapor of the metal exiting through the crucible opening and entering the arc chamber. A crucible Comprising an ion source.

15. The ion source according to claim 14, wherein the crucible opening is disposed in a wall having a temperature lower than that of the closed end.

16. The ion source according to claim 15, wherein the crucible opening is disposed in a wall on the opposite side of the closed end.

17. The ion source according to claim 14, further comprising a channel communicating with the crucible opening and the interior of the arc chamber, whereby vapor reaches the arc chamber through the channel.

18. The ion source according to claim 14, further including a porous material disposed inside the crucible in proximity to the crucible opening, whereby the vapor passes through the porous material before exiting through the crucible opening.

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