System and method for introducing aluminum into an ion source

Abstract

An ion source is disclosed which may be used to introduce a dopant material into an arc chamber. A component containing the dopant material is placed in the path of the etching gas entering the arc chamber. In some embodiments, the dopant material is in liquid form, and the etching gas moves through the liquid. In several other embodiments, the dopant material is a solid material. In some embodiments, the solid material is formed as a porous structure, thereby allowing the etching gas to flow through the solid material. In several other embodiments, one or more components of the ion source are manufactured using a material containing the dopant material, thereby allowing the etching gas to etch the component to release the dopant material.

Description

Technical Field

[0001] This application claims priority to U.S. Patent Application No. 18 / 206,910, filed Jun. 7, 2023, the entire disclosure of which is incorporated herein by reference.

[0002] Embodiments of the present disclosure relate to ion sources, and more particularly to ion sources that can be used to introduce specific dopants, such as aluminum, into an ion source.

Background Art

[0003] To generate ions used within a semiconductor processing apparatus, various types of ion sources can be used. 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 to heat the cathode, and then the cathode emits electrons into the arc chamber of the ion source. The cathode is disposed at one end of the arc chamber. A repeller can be disposed at the opposite end of the arc chamber from the cathode. The cathode and the repeller can be biased to repel electrons towards the center of the arc chamber. In some embodiments, a magnetic field is used to further confine electrons within the arc chamber. A plurality of sides are used to connect the two ends of the arc chamber.

[0004] Along one of these sides, near the center of the arc chamber, an extraction aperture is disposed through which ions generated within the arc chamber can be extracted.

[0005] In certain embodiments, it may be desirable to generate specific types of ions, such as aluminum. Conventionally, vaporizers are used to introduce a solid material called a charge. This solid material may be, for example, aluminum. However, these vaporizers have slow transition times (i.e., warm-up and cool-down times) and it is difficult to quickly switch between operating modes. Furthermore, due to the complexity and space limitations of current vaporizers, the amount of charge that can be introduced varies. Finally, vaporizers are also sensitive to stray heat, which can affect the lifespan of the charge.

[0006] Therefore, it would be beneficial to have a mechanism for introducing dopants that do not suffer from these drawbacks. [Overview of the project]

[0007] An ion source is disclosed which may be used to introduce a dopant material into an arc chamber. A component containing the dopant material is placed in a path for an etching gas, which also enters the arc chamber. In some embodiments, the dopant material is in liquid form, and the etching gas moves through the liquid. In several other embodiments, the dopant material is a solid material. In some embodiments, the solid material is formed as a porous structure, thereby allowing the etching gas to flow through the solid material. In several other embodiments, one or more components of the ion source are manufactured using a material containing the dopant material, thereby allowing the etching gas to etch the component to release the dopant material.

[0008] According to one embodiment, an ion source is disclosed. The ion source comprises an arc chamber having a gas inlet, a source of etching gas, an aluminum-containing component, and a path from the source of etching gas to the gas inlet. In this case, etching species flow through the aluminum-containing component, and a chemical reaction between the aluminum-containing component and the etching gas introduces aluminum into the arc chamber. In some embodiments, the aluminum-containing component includes a cavity containing aluminum in liquid form. In this case, the etching gas flows through the aluminum. In certain subsets of embodiments, the aluminum-containing component includes a cavity containing aluminum in solid form. In this case, the aluminum is configured as a porous structure, and the etching gas flows through the porous structure. In certain subsets of embodiments, the ion source includes a heater positioned close to the cavity to increase the reaction rate between aluminum and etching gas. In certain subsets of embodiments, the ion source includes a cooler positioned close to the cavity to control the temperature of the cavity. In some embodiments, the aluminum-containing component includes a cavity with a channel. In this case, the cavity contains aluminum in solid form, and the channel has an open wall. As a result, the etching gas reacts with the aluminum as it flows through the channel. In some embodiments, the channel comprises a grid. In some embodiments, the ion source includes a gas bushing having an internal conduit. In this case, the etching gas flows from the etching gas source through the internal conduit to the gas inlet. In this case, the aluminum-containing component is the gas bushing, which is non-limited to alumina or aluminum nitride. In some embodiments, the gas bushing comprises fins extending into the internal conduit of the gas bushing. In some embodiments, the grid is located within the internal conduit of the gas bushing. In some embodiments, the ion source includes a gas bushing having an internal conduit. In this case, the etching gas flows from the etching gas source through the internal conduit to the gas inlet. In this case, the aluminum-containing component is a coating located on the wall of the internal conduit. In some embodiments, the ion source comprises an electrode communicating with a gas inlet located within an arc chamber.In this case, the electrode comprises a porous material, the etching gas flows from the etching gas source through the electrode, and the aluminum-containing component is the electrode. In certain embodiments, the electrode is electrically biased, and multiple portions of the outer surface of the electrode are coated with a conductive material. In certain embodiments, the electrode comprises a side electrode or repeller.

[0009] According to another embodiment, an indirectly heated cathode ion source is disclosed. The indirectly heated cathode ion source comprises an arc chamber having a gas inlet, an etching gas supply source, and a gas bushing having an internal conduit communicating with the etching gas supply source and the gas inlet, and being constructed from a material containing a dopant species. In some embodiments, the dopant species includes aluminum, and the material includes alumina or aluminum nitride. In some embodiments, features are arranged within the internal conduit to increase the surface area of ​​the internal conduit. In certain subsets of embodiments, the features include fins extending into the internal conduit. In certain subsets of embodiments, the features include a grid. In certain subsets of embodiments, the grid includes a helical path.

[0010] To better understand this disclosure, refer to the accompanying drawings incorporated herein by reference. [Brief explanation of the drawing]

[0011] [Figure 1] This is an indirectly heated cathode (IHC) ion source for introducing aluminum, according to one embodiment. [Figure 2A] Figures 2A and 2B show the paths from the gas source to the arc chamber in two embodiments. [Figure 2B] Figures 2A and 2B show the paths from the gas source to the arc chamber in two embodiments. [Figure 3A] Figures 3A to 3B each show aluminum-containing components containing liquid aluminum. [Figure 3B]Figures 3A and 3B show aluminum-containing components, each containing liquid aluminum. [Figure 4] This shows an aluminum-containing component with a porous structure. [Figure 5A] Figures 5A and 5B show two embodiments that utilize the porous structure shown in Figure 4. [Figure 5B] Figures 5A and 5B show two embodiments that utilize the porous structure shown in Figure 4. [Figure 6A] Figures 6A and 6B show aluminum-containing components including channels according to two embodiments. [Figure 6B] Figures 6A and 6B show aluminum-containing components including channels according to two embodiments. [Figure 7] This shows an aluminum-containing component that utilizes a wicking rod. [Figure 8] This shows a gas bushing that functions as an aluminum-containing component according to one embodiment. [Figure 9] This shows a gas bushing that functions as an aluminum-containing component according to a second embodiment. [Figure 10] This shows an ion source with porous electrodes. [Modes for carrying out the invention]

[0012] As mentioned above, certain dopants, such as aluminum and several other metals, are typically introduced into the arc chamber using a vaporizer. However, this approach has several drawbacks. As mentioned above, vaporizers have long warm-up and cool-down times. Furthermore, vaporizers use delicate and hazardous powders as charge materials.

[0013] Figure 1 shows an IHC ion source 10 that overcomes these challenges. The IHC ion source 10 includes an arc chamber 100 having two opposing ends and a plurality of walls 101 connected to these two ends. The walls 101 of the arc chamber 100 may be constructed of a conductive material and the walls 101 may be electrically connected to each other. In some embodiments, a liner may be positioned in close proximity to one or more of the walls 101. A cathode 110 is located within the arc chamber 100 at a first end 104 of the arc chamber 100. A filament 160 is located behind the cathode 110. The filament 160 is connected to a filament power supply 165. The filament power supply 165 is configured to pass an electric current through the filament 160 so that the filament 160 emits thermionic electrons. The cathode bias power supply 115 negatively biases the filament 160 with respect to the cathode 110, so that thermionic electrons are accelerated from the filament 160 toward the cathode 110 and heat the cathode 110 when they strike the back surface of the cathode 110. The cathode bias power supply 115 can bias the filament 160, for example, so that the filament 160 has a voltage that is negative by between 200V and 1500V compared to the voltage of the cathode 110. The cathode 110 then emits thermionic electrons on its front surface into the arc chamber 100.

[0014] Therefore, the filament power supply 165 supplies current to the filament 160. The cathode bias power supply 115 biases the filament 160 such that the filament 160 is negatively polarized compared to the cathode 110, thereby inducing electrons from the filament 160 toward the cathode 110. In certain embodiments, the cathode 110 may be biased toward the arc chamber 100 by a bias power supply 111, etc. In other embodiments, the cathode 110 may be electrically connected to the arc chamber 100 such that it is at the same voltage as the walls 101 of the arc chamber 100. In these embodiments, the bias power supply 111 may not be used, and the cathode 110 may be electrically connected to the walls 101 of the arc chamber 100. In certain embodiments, the arc chamber 100 is electrically grounded.

[0015] On the second end 105 opposite to the first end 104, a repeller 120 may be arranged. The repeller 120 may be biased with respect to the arc chamber 100 by a repeller bias power supply 123. In other embodiments, the repeller 120 may be electrically connected to the arc chamber 100 so as to have the same voltage as the wall 101 of the arc chamber 100. In these embodiments, the repeller bias power supply 123 may not be used, and the repeller 120 may be electrically connected to the wall 101 of the arc chamber 100. In other embodiments, the cathode and the repeller may share a power supply. In still other embodiments, the repeller 120 is not employed.

[0016] The cathode 110 and the repeller 120 are each made of a conductive material such as metal or graphite.

[0017] In certain embodiments, a magnetic field is generated within the arc chamber 100. This magnetic field is for spatially confining electrons along a certain direction. The magnetic field typically extends from the first end 104 to the second end 105 parallel to the wall 101. For example, electrons can be spatially confined within a column parallel to the direction from the cathode 110 to the repeller 120 (i.e., the y-direction). Thus, the electrons are not affected at all by the electromagnetic force moving in the y-direction. However, the movement of electrons in other directions may be affected by the electromagnetic force.

[0018] An extraction opening 140 may be arranged on one side surface of the arc chamber 100 (referred to as the extraction plate 103). In FIG. 1, the extraction opening 140 is arranged on a side surface parallel to the Y-Z plane (perpendicular to the page). The gas inlet 190 may be arranged on one wall of the arc chamber 100.

[0019] The IHC ion source 10 is part of an ion implantation system and can include an extraction optical system, a mass spectrometer, a mass resolution aperture, a collimator, an acceleration / deceleration stage, and a workpiece holder. In particular, an extraction optical system is disposed outside and in the vicinity of the extraction aperture 140 of the IHC ion source 10. Downstream of the extraction optical system, a mass spectrometer is disposed. The mass spectrometer utilizes a magnetic field to guide the path of the extracted ions. The magnetic field affects the flight path of the ions according to their mass and charge. At the output part (i.e., the distal end) of the mass spectrometer, a mass resolution device having a resolution aperture is disposed. By appropriately selecting the magnetic field, only the ions having the selected mass and charge will be guided to pass through the resolution aperture. The other multiple ions will collide with the mass resolution device or the wall of the mass spectrometer and will not proceed further in the system.

[0020] Downstream of the mass resolution device, a collimator can be disposed. The collimator receives the extracted ions that have passed through the resolution aperture and generates a ribbon ion beam formed of multiple parallel or substantially parallel beamlets. In other multiple embodiments, the ion beam can be a spot beam. In this embodiment, an electrostatic scanner is used to move the spot beam in a first direction.

[0021] Downstream of the collimator, an acceleration / deceleration stage can be disposed. The acceleration / deceleration stage can be an electrostatic filter. The electrostatic filter is a beam line lens component configured to independently control the deflection, deceleration, and focusing of the ion beam. Downstream from the acceleration / deceleration stage, a workpiece holder is disposed. The ions extracted from the IHC ion source 10 can be guided toward a workpiece disposed on the workpiece holder. The workpiece can be a silicon wafer, a silicon carbide wafer, a gallium nitride wafer, or another semiconductor wafer.

[0022] Furthermore, the IHC ion source 10 may be in communication with at least one gas source. The gas source 170 may include an etching gas, which may be a halogen gas such as chlorine or fluorine. The etching gas may also include several other species, such as molecular species, including halogens, inert gases, hydrogen, or several other species. In another embodiment, the etching gas may be hydrogen chloride (HCl).

[0023] The valve 171 can be used to control the flow of etching gas from the gas source 170 to the IHC ion source 10.

[0024] The controller 180 may communicate with one or more of the power supplies, thereby changing the voltage or current supplied by these power supplies. The controller 180 may also communicate with the valve 171 and the cooler and heater described below. The controller 180 may include a processing unit, such as a microcontroller, a personal computer, a dedicated controller, or another suitable processing unit. The controller 180 may also include a non-temporary storage element, such as semiconductor memory, magnetic memory, or another suitable memory. This non-temporary storage element may include instructions and other data that enable the controller 180 to perform the functions described herein.

[0025] The aluminum-containing component 150 is located in the path between the gas inlet 190 and the gas source 170. The aluminum-containing component 150 can take various forms, as described below. The path between the gas source 170 and the gas inlet 190 can also be located in various positions.

[0026] For example, as shown in Figures 2A and 2B, the arc chamber 100 is mounted on a housing 50 or on an arc chamber support. The source housing 50 may be cooled to remove heat from the arc chamber 100. In some embodiments, the source housing 50 may have a hollow interior. In Figure 2A, the path may include a gas line 200 located outside the source housing 50, traveling outside the source housing 50 from a gas source 170 to an aluminum-containing component which may be a gas bushing 210. The gas bushing 210 includes an internal conduit 211. The internal conduit 211 is in fluid communication with the gas line 200 and a gas inlet 190. The gas inlet 190 may be located in one of several walls of the arc chamber 100 adjacent to the extraction plate 103. In some embodiments, the gas bushing 210 may be constructed from graphite or another suitable material. In Figure 2B, the path may be located inside the source housing 50 and include a gas line 200 and an internal chamber 230 which is an aluminum-containing component. In this embodiment, the internal chamber 230 is located between the gas source 170 and the gas inlet 190. The gas inlet 190 is located on the wall opposite the extraction plate 103. The internal chamber 230 may be constructed from graphite or another suitable material.

[0027] As described above, aluminum-containing components can take various forms. Figures 3A and 3B show a first embodiment of an aluminum-containing component. In these embodiments, the aluminum-containing component is a cavity 300. The cavity 300 is used to hold a container of liquid aluminum. The cavity 300 may have an internal volume between 1 cubic inch and 10 cubic inches. In some embodiments, there may be two or more cavities 300. The cavity 300 may be constructed of graphite or quartz. Alternatively, the cavity 300 may be produced using a high-melting-point metal such as stainless steel, tungsten, or tantalum. The source for the liquid aluminum may take the form of solid pellets, shavings, or some other form. The aluminum used in this embodiment may be pure aluminum, such as aluminum 1100. In this disclosure, the term “pure aluminum” is used to describe a metal that is at least 80% aluminum, such as pure aluminum between 80% and 99.999%. This cavity 300 may be the internal chamber 230 shown in Figure 2B, or it may be a void within the gas bushing 210 (see Figure 2A). A heater 310 is positioned close to the cavity 300 to heat the solid aluminum above its melting point and convert the aluminum into a liquid state. In some embodiments, the heater 310 may surround the cavity 300 on all sides. Furthermore, a temperature sensor may be positioned close to the cavity to monitor the temperature of the cavity 300. A gas line 200 provides fluid communication between the gas source 170 and the cavity 300. In another embodiment, the etching gas is heated before being introduced into the cavity 300. The temperature of the heated etching gas may be sufficient to cause the aluminum in contact with the gas to melt.

[0028] In the embodiment shown in Figure 3A, a plug 301 may be positioned at the entrance to the cavity 300. The diameter of the hole in the plug 301 is dimensionally determined such that the surface tension of the liquid aluminum is sufficiently high to prevent it from passing through the plug 301. The plug 301 may consist of graphite foam, quartz wool, or some other suitable material. However, the etching gas can flow through the plug 301. The etching gas passes through the liquid aluminum as it moves towards the gas inlet 190.

[0029] In the embodiment shown in Figure 3B, called a reentrant design, the gas line 200 enters the upper part of the cavity 300 and is immersed in the liquid aluminum. Etching gas bubbles pass through the liquid aluminum as they move to the gas inlet 190.

[0030] In both embodiments, the etching species react with the liquid aluminum to form a dopant gas containing aluminum-containing molecules. For example, if the etching gas contains chlorine, the dopant gas may be aluminum chloride. Furthermore, it should be noted that the dopant gas is generated as long as the etching gas is flowing through the liquid aluminum. When valve 171 is closed, the flow of the dopant gas stops.

[0031] In several other embodiments, the aluminum-containing component comprises aluminum in solid form.

[0032] Figure 4 shows one embodiment in which the aluminum-containing component is a cavity that holds a porous structure. In this embodiment, the aluminum is in solid form and constitutes the porous structure 400. For example, the aluminum may be in the form of foam, grid, pellets, or aluminum matrix. The porous structure 400 is located within the cavity 350. The cavity 350 may be constructed of a material such as graphite that is more resistant to etching gases than the porous structure 400. To increase the reaction rate between the porous structure 400 and the etching gas, a heater 310 may be placed close to the cavity 350 and used to heat the porous structure 400. Furthermore, in some embodiments, a cooler 320 may be included. For example, if the etching gas is chlorine, the reaction between aluminum and chlorine is exothermic. Therefore, to prevent thermal runaway, a cooler 320 is used to maintain a desired temperature range and prevent the aluminum material from melting. In one non-limiting embodiment, the temperature range may be set to 400-450°C to allow for a higher reaction rate and may be well below the nominal melting point of aluminum. For example, the desired temperature can be maintained at a temperature 10-40% lower than the melting point of aluminum. Therefore, in some embodiments, the heater 310 is used when the etching gas flow is initiated. However, it may be possible to deactivate the heater 310 once the reaction rate reaches a certain threshold. Furthermore, as the reaction continues, the cooler 320 can be activated to control the exothermic reaction. For example, the heater 310 and the cooler 320 can be used together to precisely control the temperature of the aluminum material.

[0033] It should be noted that the porous structure 400 may be pure aluminum. However, in several other embodiments, the porous structure 400 may be, non-limitingly, an aluminum compound containing AlN or alumina. Thus, the porous structure 400 may be called an aluminum-containing porous structure. This structure includes several structures made of pure aluminum, aluminum alloys, and / or several other aluminum compounds such as alumina, aluminum nitride, or other ceramics.

[0034] The embodiment shown in Figure 4 can be implemented in various ways. Figures 5A and 5B show two embodiments that use an aluminum-containing porous structure.

[0035] In Figure 5A, the cavity 350 is located within the source housing 50. The porous structure 400 is located within the cavity 350. The gas source 170 is in fluid communication with the cavity 350 through the valve 171 and the gas line 200. Furthermore, the cavity 350 is in communication with the gas inlet 190. The gas inlet 190 may be located on the side of the arc chamber 100 opposite the extraction plate 103.

[0036] In Figure 5B, the cavity 350 is located within the gas bushing 210. The gas bushing 210 is attached to a gas inlet 190 located on the chamber wall, which may be adjacent to the extraction plate 103. The gas bushing 210 has an internal conduit 211 having an inlet communicating with the gas line 200 and an outlet attached to the IHC ion source 10. The cavity 350 is preferably located at the inlet or outlet of the internal conduit 211. Thereafter, the cavity 350 can be easily replaced. In some embodiments, the gas bushing 210 can be expanded to accommodate an internal heater, as shown in Figures 4 and 5A.

[0037] In Figures 5A and 5B, as the etching gas flows through the cavity 350, it moves through the porous structure and reacts with it to generate molecules or ions containing dopant species, which in this embodiment may be aluminum. The flow of dopant species is easily controlled by activating valve 171.

[0038] Therefore, Figures 5A and 5B both show a cavity 350 in which a porous structure 400 is located. The cavity 350 is positioned so that etching gas flows through the gas line 200 and through the porous structure 400. The interaction between the porous structure 400 and the etching gas causes the formation of a dopant gas. The dopant gas then flows through the gas inlet 190 to the arc chamber 100. As shown in the figures, the cavity 350 may be located within the source housing 50 or the gas bushing 210. When consumed, the cavity 350 can be accessed by an operator to replace the porous structure 400. Thus, in Figures 4 and 5A to 5B, the aluminum-containing component may be a cavity in which an aluminum-containing porous structure is located inside. In these embodiments, etching gas flows through the porous structure 400.

[0039] The porosity of the porous structure 400 may be constant throughout the structure. In several other embodiments, the porosity may vary. For example, the porosity may be higher near the gas line 200 where the etching gas first comes into contact with the porous structure. Furthermore, in several specific embodiments, the density of the porous structure 400 may be constant. In several other embodiments, the density may vary. By varying the porosity and / or density, the distribution of the etching gas through the porous structure can be made more uniform.

[0040] However, in several other embodiments, the cavity may be constructed differently. In some embodiments, the cavity may be filled with a solid charge such as aluminum. In certain embodiments, the cavity may also include a channel through which an etching gas passes. The channel may have openings in its walls so that the etching gas reacts with the charge. This configuration may allow for a larger volume of charge. This configuration is shown in Figures 6A and 6B. In Figure 6A, the cavity 600 is located inside the source housing 50. The cavity 600 includes a channel 610 that fluidly communicates with the gas line 200 and the gas inlet 190. The channel 610 may have a lattice structure such as a gyroid structure, a honeycomb structure, a ball-and-beam structure, or another structure that allows the walls of the channel 610 to include openings. A solid material 620 is then loaded into the cavity 600. The solid material 620 is in contact with the channel 610. This allows the etching gas to react with the solid material 620 as it flows through the channel 610, where possible. In Figure 6B, the cavity 600 is located within the gas bushing 210. The channel 610 is in fluid communication with the gas line 200 and the gas inlet 190. As described above, the channel 610 may be a grid. The solid material 620 is then loaded into the cavity 600. This allows the etching gas to come into contact with the solid material 620 as it passes through the channel 610. It should be noted that the size of the gas bushing 210 may be enlarged in this embodiment to hold the solid material 620. Furthermore, the enlarged size may allow for the incorporation of a heater, if desired.

[0041] Therefore, in the embodiments shown in Figures 6A and 6B, the aluminum-containing component is a cavity having a solid material containing a dopant species such as aluminum placed inside. A channel is located within the cavity and provides a path for etching gas to move. The channel includes an opening in its outer wall. Thereafter, as the etching gas moves through the channel, it comes into contact with the solid material and generates molecules or ions containing the dopant species.

[0042] In certain embodiments, the etching gas may be hydrogen chloride (HCl). In this embodiment, catalytic components such as wires, meshes, or grids coated with platinum, ruthenium-platinum, or another catalytic material are placed near the aluminum charge. For example, Figure 4 includes a catalytic component 401 placed near the porous structure 400. Although not shown, the catalytic component 401 may also be introduced in embodiments shown in Figures 5A-5B and 6A-6B.

[0043] Figure 7 shows a modified configuration of the configuration shown in Figures 6A-6B. In this embodiment, a wicking rod 710 is used instead of having a channel adjacent to the solid material. Specifically, the gas bushing 210 has an internal conduit 211 as described above. The wicking rod 710 extends into the internal conduit 211. The wicking rod 710 may be solid or may have a hollow central portion to form a tube. The distal end of the wicking rod 710 is located in a cavity 700 that extends downward from the internal conduit 211. The cavity 700 may be incorporated into the gas bushing 210 or may be a separate component. A heater 720 may be located adjacent to the cavity 700 if desired. During operation, the solid material (which may be or may contain a dopant species) is deposited in the cavity 700. The heater 720 is used to melt the solid material. Further heat may be provided by the arc chamber 100. The liquid material then rises up the wicking rod 710 towards the internal conduit 211. In some embodiments, the Venturi effect may also be used to pull the material out of the cavity 700 as the gas flows through the internal conduit 211. The etching gas flowing through the internal conduit 211 reacts with the liquid material placed inside the wicking rod 710 to produce gaseous molecules containing dopant species. These molecules pass through the gas inlet 190 and enter the arc chamber 100.

[0044] In each of the several embodiments described above, a consumable part was inserted into a cavity. This consumable part may be a porous structure, such as those shown in Figures 4 and 5A-5B. Alternatively, the consumable part may be a charge of aluminum loaded into the cavity, as shown in Figures 3, 6A-6B, and 7. Thus, in each of these embodiments, the aluminum-containing part includes a cavity that holds the aluminum material.

[0045] However, other embodiments are also feasible. For example, instead of inserting a consumable part into a cavity, the aluminum-containing part could be one of the existing gas bushings that are part of the IHC ion source 10.

[0046] For example, Figure 8 shows one embodiment in which the gas bushing 210 acts as an aluminum-containing component. In this embodiment, the gas bushing 210 is not made of graphite or another non-erosion material. Rather, the gas bushing 210 is made of a material containing a dopant species. In one non-limiting embodiment, when the dopant species is aluminum, the gas bushing 210 may be constructed from aluminum nitride, alumina, or another aluminum-containing ceramic. Furthermore, to increase the amount of interaction between the etching gas and the gas bushing, features that increase the surface area of ​​the internal conduit 211 may be incorporated into the internal conduit 211. For example, Figure 8 shows a fin 212 extending into the internal conduit 211. The fin 212 is integral with the gas bushing 210, which may be produced using an additive manufacturing process. The fin 212 is considerably thinner than the outer wall of the gas bushing 210. Thereafter, the fin 212 is eroded much more rapidly than the rest of the gas bushing 210. For example, the outer wall of the gas bushing 210 can be at least four times thicker than the fins 212. In some embodiments, the fins 212 may extend into the internal conduit 211 and have a height between 25% and 75% of the height of the internal conduit 211. The fins 212 may be arranged alternately such that when a first fin extends downward, the fins on either side of that first fin extend upward into the internal conduit 211. The spacing between adjacent fins 212 may be varied and selected to increase the surface area without restricting the flow rate. During operation, as etching gas flows through the gas bushing 210, the etching gas erodes the fins 212 and supplies aluminum to the gas inlet 190 of the arc chamber 100. The shape, size, thickness, and spacing of the fins 212 may be varied to facilitate erosion.

[0047] Fins are just one possible mechanism for increasing the surface area of ​​the internal conduit 211. Figure 9 shows another embodiment. In this embodiment, a grid 213, which may be a gyroid, honeycomb, or ball-and-beam structure, is incorporated into the internal conduit 211. The wall thickness of the grid 213 is 0.015 inches or more, and the spacing between the walls is also similar. The grid 213 is integral with a gas bushing 210, which may be produced using an additive manufacturing process. The grid 213 may have a constant porosity and density. In several other embodiments, at least one of the porosity or density varies along the internal conduit 211. During operation, as etching gas flows through the gas bushing 210, the etching gas erodes the grid 213, supplying aluminum to the gas inlet 190 of the arc chamber 100. The grid 213 may change shape, size, and density to facilitate erosion.

[0048] In another modification shown in Figure 9, the grid is configured such that there are spiral paths passing through grid 213. This increases the surface area of ​​the grid and accelerates the erosion of grid 213.

[0049] While the above description discloses the use of aluminum as the dopant species, it should be understood that the gas bushings shown in Figures 8 and 9 can be used with different dopant species. For example, the dopant species may be germanium, indium, gallium, or another similar material, and the gas bushing may be constructed from a solid containing the dopant material. Furthermore, other Group IV elements, halides, or Group IV-containing compounds may be used.

[0050] Furthermore, although aluminum has been described, several other materials with melting points below the usable vapor pressure temperature used to supply ions to the ion source may also be used.

[0051] Furthermore, while Figures 8 and 9 illustrate sacrificial gas bushings, several other embodiments are possible. For example, in one embodiment, the exterior of the gas bushing 210 may be covered with an incorrosive material such as graphite. This method reduces the possibility of punch-through occurring after the gas bushing 210 has been corroded.

[0052] In another embodiment, the gas bushing is made of a non-corrosive material such as graphite or tungsten. The internal conduit 211 may be coated with a material containing a dopant species. The coating may be pure aluminum or an aluminum-containing material such as an aluminum-based ceramic. In this embodiment, non-corrosive fins may be present. These fins are also coated.

[0053] Several other components can also be used as sources of dopant material. Figure 10 shows a top view of the arc chamber 100 according to another embodiment. In this configuration, side electrodes 800 are present. During operation, one or both of the side electrodes 800 can be electrically biased. In this embodiment, the side electrodes 800 are also used to supply dopant material to the arc chamber 100. Like the gas bushing described above, the side electrodes 800 can be constructed from a solid material containing a dopant species such as alumina or aluminum nitride, but not limited to this. The side electrodes 800 may be formed to be porous and may have a gradient between porosity and density. For example, the side electrodes 800 may be denser on the back surface 801 facing the wall 101 and less dense on the exposed surface 802 that interacts with the plasma. The gas inlet 190 is attached to the back surface 801 of the side electrodes 800. The porosity of the side electrode 800 may be such that a continuous path exists from the gas inlet 190 through the side electrode 800 to another surface, such as the exposed surface 802. In this manner, the etching gas moves through channels within the side electrode 800 and etches the dopant material as the etching gas passes through the electrode. This dopant material is then introduced into the arc chamber 100. As described above, in certain embodiments, the side electrode 800 may be electrically biased. In these embodiments, a conductive material such as tungsten may be placed on multiple portions of the outer surface of the side electrode 800. This conductive material is connected to the electrode power supply 810.

[0054] This concept can also be applied to other electrodes placed within the arc chamber, such as the repeller 120. The repeller 120 may be formed from a porous solid material containing a dopant, as described above. In this embodiment, the gas inlet 190 may communicate with the back surface of the repeller 120. As described above, a conductive material may be added to several portions of the outer surface to allow the repeller 120 to be biased by the repeller bias power supply 123.

[0055] While this disclosure has described the introduction of dopant species such as aluminum by passing an etching gas through an aluminum-containing component, it should be understood that there may be other gases used within the arc chamber. For example, another gas inlet may be used to introduce a second gas into the arc chamber. This second gas may also contain dopant species, be a diluent gas, or be another gas.

[0056] The multiple embodiments described above in this application may have many advantages. As described above, vaporizers are commonly used to supply aluminum to the arc chamber. However, vaporizers have a long transition time when heating the vaporizer to the desired temperature and then cooling the vaporizer. In each of these embodiments, the dopant gas containing aluminum enters the arc chamber only when there is a flow of etching gas. Thus, by acting valve 171, it is possible to enable or disable the flow of dopant gas much more quickly than is done using a vaporizer. Furthermore, vaporizers are sensitive to stray heat, which can affect the amount of vapor produced. In contrast, the flow rate of dopant gas is much easier to control using etching gas. Several other advantages of these embodiments compared to the prior art (vaporizers) include greater flexibility in design and operation, greater power output, larger amounts of dopant material allowing for longer source life, and better stability and reliability leading to a higher mean interval between failures. The materials used in these embodiments may also be more chemically stable when interacting with the atmosphere compared to the highly reactive materials frequently used in vaporizers. This leads to a significant improvement in storage, handling, and operational safety. Furthermore, the materials used in these embodiments are typically more affordable than alternatives.

[0057] This disclosure is not limited in scope by the specific embodiments described herein. In fact, a number of other embodiments and modifications to this disclosure will be obvious to those skilled in the art from the foregoing description and accompanying drawings, in addition to the embodiments of this disclosure described herein. Therefore, such other embodiments and modifications are intended to be included within the scope of this disclosure. Furthermore, while this disclosure is described herein in the context of a specific implementation in a specific environment for a specific purpose, a person skilled in the art will recognize that the usefulness of this disclosure is not limited to this context, and that it can be beneficially implemented for several purposes in several environments. Accordingly, the claims described below should be interpreted in light of the entire scope and essence of this disclosure as described herein.

Claims

1. Arc chamber equipped with a gas inlet, Etching gas supply source, Aluminum-containing parts, and The etching gas has a path from the supply source through the gas inlet to the arc chamber, The etching gas flows through the aluminum-containing component, and the chemical reaction between the aluminum-containing component and the etching gas introduces aluminum into the arc chamber, in an indirectly heated cathode ion source.

2. The indirect heating cathode ion source according to claim 1, wherein the aluminum-containing component includes a cavity containing aluminum in liquid form, and the etching gas flows through the aluminum.

3. The indirectly heated cathode ion source according to claim 1, wherein the aluminum-containing component includes a cavity containing aluminum in a solid form, the aluminum is configured as a porous structure, and the etching gas flows through the porous structure.

4. The indirect heating cathode ion source according to claim 3, further comprising a heater positioned in close proximity to the cavity in order to increase the reaction rate between the aluminum and the etching gas.

5. The indirect heating cathode ion source according to claim 4, further comprising a cooler positioned in close proximity to the cavity for controlling the temperature of the cavity.

6. The indirectly heated cathode ion source according to claim 1, wherein the aluminum-containing component includes a cavity having a channel, the cavity containing aluminum in a solid form, and the channel has an open wall so as the etching gas flows through the channel, it reacts with the aluminum.

7. The channel comprises a grid, as described in claim 6, for the indirectly heated cathode ion source.

8. The indirectly heated cathode ion source according to claim 1, further comprising a gas bushing having an internal conduit, wherein the etching gas flows from the source of the etching gas through the internal conduit to the gas inlet, and the aluminum-containing component is the gas bushing, the gas bushing being made of alumina or aluminum nitride.

9. The indirect heating cathode ion source according to claim 8, wherein the gas bushing comprises fins extending into the internal conduit of the gas bushing.

10. The indirect heating cathode ion source according to claim 8, further comprising a grid disposed within the internal conduit of the gas bushing.

11. The indirectly heated cathode ion source according to claim 1, further comprising a gas bushing having an internal conduit, wherein the etching gas flows from the source of the etching gas through the internal conduit to the gas inlet, and the aluminum-containing component is a coating disposed on the wall of the internal conduit.

12. The indirect heating cathode ion source according to claim 1, further comprising an electrode disposed within the arc chamber and communicating with the gas inlet, wherein the electrode comprises a porous material, the etching gas flows from the etching gas supply source through the electrode, and the aluminum-containing component is the electrode.

13. The indirectly heated cathode ion source according to claim 12, wherein the electrode is electrically biased and a plurality of portions of the outer surface of the electrode are coated with a conductive material.

14. The indirect heating cathode ion source according to claim 12, wherein the electrode includes a side electrode or a repeller.

15. Arc chamber equipped with a gas inlet, Source of etching gas, and An indirectly heated cathode ion source comprising a gas bushing having an internal conduit communicating with the source and gas inlet of the etching gas, and the gas bushing being constructed from a material containing a dopant species.

16. The indirectly heated cathode ion source according to claim 15, wherein the dopant species comprises aluminum, and the material comprises alumina or aluminum nitride.

17. The indirect heating cathode ion source according to claim 15, wherein a feature is arranged inside the internal conduit to increase the surface area of ​​the internal conduit.

18. The indirect heating cathode ion source according to claim 17, wherein the feature includes a fin extending into the internal conduit.

19. The indirectly heated cathode ion source according to claim 17, wherein the feature includes a lattice.

20. The indirectly heated cathode ion source according to claim 19, wherein the lattice includes a helical path.

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