Ion source having different operating modes

Abstract

An ion source capable of different operation modes is disclosed. A vaporizer communicates with the ion source. The ion source can have a plurality of gas inlets communicating with different gases. When operating in the first mode, the ion source can supply a first gas, such as an inert gas, while heating the vaporizer. When operating in the second mode, the ion source can supply a second gas, and the second gas can be an organoaluminum gas. When operating in the third mode, the ion source can supply the second gas while heating the vaporizer. Ions having a single charge can be generated in the first and second modes, while ions having multiple charges can be generated in the third mode.

Description

Technical Field

[0001] This application claims priority to U.S. Patent Application No. 17 / 834,445, filed on June 7, 2022, 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 having multiple modes for generating ions of species having different charges.

Background Art

[0003] To generate ions for use in semiconductor processing equipment, 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 the cathode. The filament emits thermoelectrons, 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. A repeller can be disposed at the end of the arc chamber opposite the cathode. The cathode and the repeller can be biased to repel electrons and direct them 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. A plurality of sides are used to connect the two ends of the arc chamber.

[0004] An extraction aperture is disposed along one of these sides proximate to the center of the arc chamber, and ions generated within the arc chamber can be extracted through the extraction aperture.

[0005] In certain embodiments, it may be desirable to generate ions having a single charge. However, in other embodiments, it may be desirable to generate polyvalent ions. Unfortunately, for certain materials such as aluminum and other metals, the mechanisms used to generate monovalent ions may not be effective when generating polyvalent ions. Thus, different ion sources may be utilized depending on the desired charge of the extracted ions.

[0006] This solution is costly because it utilizes multiple ion sources. Further, this solution is time consuming because it takes time to switch from one ion source to another.

[0007] Thus, a single ion source that can operate in different modes to generate ions having different charges would be beneficial. Further, it would be advantageous if the arc chamber could be quickly changed from one mode to another. SUMMARY OF THE INVENTION

[0008] An ion source capable of different operating modes is disclosed. A vaporizer is in communication with the ion source. The ion source can have a plurality of gas inlets in communication with different gases. When operating in a first mode, the ion source can supply a first gas, such as an inert gas, while heating the vaporizer. When operating in a second mode, the ion source can supply a second gas, which can be an organoaluminum gas. When operating in a third mode, the ion source can supply the second gas while heating the vaporizer. Ions having a single charge can be generated in the first and second modes, while ions having multiple charges can be generated in larger quantities in the third mode.

[0009] According to one embodiment, an indirectly heated cathode ion source is disclosed. The indirectly heated cathode ion source includes an arc chamber having a plurality of walls, an indirectly heated cathode disposed within the arc chamber, a vaporizer in communication with the arc chamber, a heater for heating a dopant material disposed within the vaporizer, a first valve in communication with the arc chamber and a first gas source, a second valve in communication with the arc chamber and a second gas source, and a controller in communication with the first valve, the second valve, and the heater to operate the indirectly heated cathode ion source in one of a plurality of modes. In some embodiments, the plurality of modes includes two single charge modes for generating ions of species having a single charge and a multi-charge mode for generating ions of species having two or more charges. In some embodiments, the species includes a metal. In some embodiments, in the first single charge mode, the controller activates the heater, opens the first valve, and closes the second valve. In some embodiments, in the second single charge mode, the controller deactivates the heater and opens the second valve. In certain embodiments, in the second single charge mode, the controller opens the first valve. In some embodiments, in the multi-charge mode, the controller activates the heater and opens the second valve. In some embodiments, the dopant material disposed within the vaporizer includes a solid compound containing a metal, and the metal is also a component of a second gas included in the second gas source. In certain embodiments, the metal is aluminum and the dopant material disposed within the vaporizer is aluminum chloride. In certain embodiments, the metal is aluminum and the dopant material disposed within the vaporizer is aluminum iodide. In some embodiments, the metal is aluminum, the first gas source includes an inert gas, and the second gas source includes dimethylaluminum chloride or trimethylaluminum chloride.

[0010] According to another embodiment, a method of operating an indirectly heated cathode ion source in a plurality of modes, the indirectly heated cathode ion source comprising a controller, an arc chamber, a vaporizer in communication with the arc chamber, and a heater for heating a dopant material within the vaporizer, is disclosed. The method includes selecting a desired operating mode and configuring the indirectly heated cathode ion source to operate in the desired mode using the controller. For operation in a multi-charge mode, the multi-charge mode is used to generate ions of species having two or more charges, the heater is operated such that the vaporized dopant material containing the metal enters the arc chamber, and the controller enables the flow of the metal-containing gas into the arc chamber. In a first single-charge mode, the first single-charge mode is used to generate ions of species having a single charge, the controller operates the heater and enables the flow of an inert gas into the arc chamber. For operation in a second single-charge mode, the second single-charge mode is used to generate ions of species having a single charge, the controller causes the heater not to operate and uses the metal-containing gas to generate a plasma. In some embodiments, the metal is aluminum and the dopant material disposed within the vaporizer is aluminum chloride.

[0011] In some embodiments, the metal is aluminum and the dopant material disposed within the vaporizer is aluminum iodide. In some embodiments, the metal is aluminum and the metal-containing gas includes DMAC or TMAC.

[0012] According to another embodiment, an indirectly heated cathode ion source is disclosed. The indirectly heated cathode ion source includes an arc chamber having a plurality of walls, a vaporizer in communication with the arc chamber, and an indirectly heated cathode disposed within the arc chamber, wherein the indirectly heated cathode is used to generate plasma within the arc chamber, and a controller configured to operate the indirectly heated cathode ion source in one of a plurality of modes, wherein in the multi-charge mode, the controller configures the indirectly heated cathode ion source such that two sources of metal are used to generate plasma, and a controller. In some embodiments, the metal is aluminum, the material disposed within the vaporizer includes aluminum chloride, and a gas containing aluminum is introduced into the arc chamber when operating in the multi-charge mode. In some embodiments, the metal is aluminum, the material disposed within the vaporizer includes aluminum iodide, and a gas containing aluminum is introduced into the arc chamber when operating in the multi-charge mode. In a particular embodiment, in the single-charge mode, only one of the two sources is introduced into the arc chamber.

[0013] To better understand the present disclosure, reference is made to the accompanying drawings which are incorporated herein by reference.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0015] As described above, certain dopants such as aluminum and other metals utilize different mechanisms to generate monovalent and polyvalent ions.

[0016] FIG. 1 shows an IHC ion source 10 that solves these problems. 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 made of 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. A cathode 110 is disposed within 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 communicates with a filament power supply 165. The filament power supply 165 is configured to pass a current through the filament 160 such that the filament 160 emits thermoelectrons. A cathode bias power supply 115 applies a negative bias to the filament 160 with respect to the cathode 110, and thus these thermoelectrons are accelerated from the filament 160 toward the cathode 110 and heat the cathode 110 when the thermoelectrons strike the back surface of the cathode 110. The cathode bias power supply 115 can bias the filament 160 such that the filament 160 has a voltage that is, for example, 200 V to 1500 V negative with respect to the voltage of the cathode 110. The cathode 110 then emits thermoelectrons on the front surface of the cathode into the arc chamber 100.

[0017] Therefore, 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, and thus electrons are attracted from the filament 160 toward the cathode 110. In certain embodiments, the cathode 110 can be biased with respect to the arc chamber 100 by a bias power supply 111 or the like. 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 bias power supply 111 may not be used, and the cathode 110 can be electrically connected to the wall 101 of the arc chamber 100. In certain embodiments, the arc chamber 100 is connected to electrical ground.

[0018] A repeller 120 can be disposed on the second end 105 opposite the first end 104. The repeller 120 can be biased with respect to the arc chamber 100 using 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 used, and the repeller 120 can be electrically connected to the wall 101 of the arc chamber 100. In still other embodiments, the repeller 120 is not used.

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

[0020] In certain embodiments, a magnetic field is generated within the arc chamber 100. This magnetic field is for confining electrons along one direction. The magnetic field typically runs parallel to the wall 101 from the first end 104 to the second end 105. For example, the electrons can be confined in a cylinder parallel to the direction from the cathode 110 to the repeller 120 (i.e., the y direction). Thus, the electrons do not receive any electromagnetic force in the y direction. However, the electrons can receive electromagnetic forces for their movement in other directions.

[0021] An extraction opening 140 can be disposed on one side surface of the arc chamber 100, called an extraction plate 103. In FIG. 1, the extraction opening 140 is disposed on a side surface parallel to the Y-Z plane (perpendicular to the page).

[0022] Furthermore, the IHC ion source 10 can communicate with at least two gas sources. The first gas source 170 can contain a first gas, and the first gas can be an inert gas such as argon. The first valve 171 can be used to control the flow of the first gas from the first gas source 170 to the IHC ion source 10. The second gas source 175 can contain a second gas that is an organoaluminum compound, which is a compound in which aluminum atoms are bonded by carbon atoms. In certain embodiments, the organoaluminum compound contains halogen and aluminum. In certain embodiments, the second gas can be dimethylaluminum chloride (DMAC, (CH3)2AlCl) or trimethylaluminum chloride (TMAC, (CH3)3AlCl). Other gases containing metal atoms bonded to carbon atoms can also be used. In some embodiments, this second gas contains carbon, metal, and halogen. The second gas source 175 can also contain various dilution gases, such as hydrogen, argon, or other gases. In other words, the second gas source 175 contains the second gas, but can also contain other gases. The second valve 176 can be used to control the flow of the second gas from the second gas source 175 to the ion source 10. The first valve 171 and the second valve 176 can be mass flow controllers (MFCs) so that the flow rates can be controlled.

[0023] The vaporizer 190 can communicate with the arc chamber 100. For example, the vaporizer can be disposed outside the arc chamber 100, but can include a conduit 191 that connects the output of the vaporizer to the arc chamber 100. The heater 195 can be disposed proximate to the vaporizer 190 to heat and vaporize the dopant material 197 disposed within the vaporizer 190. The heater 195 can be a resistive heater or another type. The design of the heater is implementation-specific and is not limited by the present disclosure. In certain embodiments, the dopant material 197 within the vaporizer 190 can be a solid compound containing a metal. For example, the dopant material 197 can be aluminum chloride or aluminum iodide. In other embodiments, the dopant material 197 within the vaporizer 190 can be gallium iodide, indium iodide, aluminum iodide, lanthanum fluoride, or another solid compound containing a metal and a halogen. The metal contained in the dopant material 197 is the same metal as that contained in the second gas.

[0024] The controller 180 can communicate with one or more of the power supplies such that the voltage or current supplied by these power supplies can be changed. The controller 180 can also communicate with the first valve 171, the second valve 176, and the heater 195. The controller 180 can include a processing device, such as a microcontroller, a personal computer, a dedicated controller, or another suitable processing device. 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.

[0025] In the embodiment shown in FIG. 1, the controller 180 is configured to enable the ion source 10 to operate in a plurality of different modes. These modes include a first single-charge operation mode, a second single-charge operation mode, and a multi-charge operation mode. Each of these modes will be described in more detail.

[0026] In the first single-charge operation mode, the filament power supply 165 passes current through the filament 160, which causes the filament 160 to emit thermoelectrons. These electrons strike the back of the cathode 110, which can be positive relative to the filament 160, heating the cathode 110, whereby the cathode 110 emits electrons into the arc chamber 100. These electrons collide with the molecules of the gas supplied into the arc chamber 100 through the gas inlet.

[0027] The controller 180 opens the first valve 171 to allow the flow of the first gas into the arc chamber 100. The first gas can be an inert gas. The controller 180 also controls the heater 195 so as to heat the dopant material 197 in the vaporizer 190 to a temperature such that the dopant material 197 is vaporized and the vaporized dopant material enters the arc chamber 100 through the conduit 191. By combining the electrons from the cathode 110, the first gas, and the vaporized dopant material, a plasma is generated. The ions in this plasma can generally be monovalent ions such as Al + and the like. In certain embodiments, the electrons and positive ions can be somewhat confined by a magnetic field. In certain embodiments, the plasma is confined near the center of the arc chamber 100, close to the extraction aperture 140. Thus, in this first single-charge mode, the metal is introduced only by the vaporized dopant material.

[0028] Thus, when it is desired to generate monovalent ions such as Al + and the like, the operator can send this preference to the controller 180. Alternatively, the controller 180 can determine the desired mode based on the desired charge state and beam current. Accordingly, the controller 180 can execute the sequence described above.

[0029] In the second single-charge mode, the controller opens the second valve 176 to allow the flow of a second gas, which is a gas containing the same metal as the dopant material 197, into the arc chamber 100. The controller 180 also deactivates the heater 195 so that the vapor from the vaporizer 190 does not enter the arc chamber 100. The second gas is ionized to create metal ions, mostly having a single charge. Further, when the second gas contains a halogen, the halogen in the second gas serves to recycle the metal from the walls of the arc chamber 100. Thus, in this second single-charge mode, the metal is introduced only by the second gas. In certain embodiments, the first valve 171 can be opened to allow the flow of the first gas into the arc chamber 100. In other embodiments, the first valve 171 is closed.

[0030] In the multi-charge mode, the controller 180 opens the second valve 176 to allow the flow of the second gas into the arc chamber 100. As described above, the second gas can be a gas containing the same metal as the dopant material 197. For example, when the metal is aluminum, the second gas can be DMAC or TMAC. These gases are useful in that the gas effectively recycles the metal from the walls of the arc chamber 100. The controller also activates the heater 195 so that the vaporized dopant material from the vaporizer 190 also enters the arc chamber 100 via the conduit 191. As described above, the metal in the vaporized dopant material is the same metal that is a component of the second gas. Since both the second gas and the vaporized dopant material contain the same metal, a plasma rich in this metal is generated. Depending on the density of the metal in the plasma, many of the ions generated in the plasma can be multi-valent ions such as Al ++ or Al +++ etc. The ions are then extracted through the extraction aperture 140 and can be used as an ion beam.

[0031] In certain embodiments, the controller 180 can also open the first valve 171 to allow some of the first gas to flow into the arc chamber 100. Thus, in the enhanced mode, the second valve 176 can be opened and the first valve 171 can be opened and closed.

[0032] Thus, when it is desired to generate polyvalent ions, the operator can send this preference to the controller 180. Alternatively, the controller 180 can determine the desired mode based on the desired charge state and beam current. Accordingly, the controller 180 can execute the sequence described above.

[0033] Thus, with respect to the embodiment shown in FIG. 1, the present application describes three different operating modes that can be used to generate different charge states of a desired dopant. Further, by incorporating the first gas, the second gas, and the vaporizer 190 that communicates with the arc chamber 100, the ion source 10 can easily switch from one mode to another without operator intervention. FIG. 2 shows the operation of the controller 180 that controls the mode of the ion source 10 when the vaporizer 190 communicates with the arc chamber 100. As shown in box 200, the desired operating mode is selected, and this selection can depend on the strategy being used. This mode can be selected by the operator or user. Alternatively, the controller 180 can automatically select the optimal mode based on the desired beam current or charge state. Based on this selection, the controller 180 operates the first valve 171, the second valve 176, and the heater 195 to achieve the desired operating mode. Typically, since the charge of the dopant material in the vaporizer 190 is limited, the second gas source is used for most Al + to be used in the operation.

[0034] As shown in box 210, a multi-charge mode can be selected and the plasma conditions are optimized for the generation of polyvalent metal ions. Accordingly, the controller 180 opens the second valve 176 to allow the flow of a second gas, which is a gas containing the same metal as the dopant material 197, into the arc chamber 100. The controller 180 can optionally open or close the first valve 171. The controller 180 also activates the heater 195 so that the vaporized dopant material from the vaporizer 190 also enters the arc chamber 100 through the conduit 191. This vaporized dopant material contains the same metal as the second gas. Since there are two sources of metal, the plasma is rich in metal ions. This plasma rich in this metal is effective when generating polyvalent ions and can achieve a polyvalent ion current that exceeds using either metal source separately.

[0035] Alternatively, as shown in box 220, a first single-charge mode can be selected and the majority of the metal ions have a single charge. Accordingly, the controller 180 opens the first valve 171 to allow the flow of a first gas, which can be an inert gas such as argon, into the arc chamber 100. In this mode, the controller 180 activates the heater 195 so that the vaporized dopant material enters the arc chamber 100 through the conduit 191. The inert gas is ionized by the vaporized dopant material in the plasma and the majority of the generated ions are monovalent ions.

[0036] As shown in box 230, a second single charge mode can be selected, and the majority of metal ions have a single charge. In the second single charge mode, the controller 180 deactivates the heater 195 so that the vaporized dopant material does not enter the arc chamber 100. Further, in this mode, the controller controls the second valve 176 to allow the flow of a second gas into the arc chamber 100. The second gas is ionized to create metal ions, which mostly have a single charge. In some embodiments, the first valve 171 is also opened to allow the flow of the first gas into the arc chamber 100. In other embodiments, the first valve is closed. Further, the halogen in the second gas serves to recycle the metal from the walls of the arc chamber 100. Thus, in this second single charge mode, the metal is introduced only by the second gas.

[0037] Thus, to operate in the multi-charge mode, the controller 180 configures the ion source 10 so that the metal is introduced by the second gas and the vaporized dopant material. To operate in the single charge mode, the controller 180 configures the ion source 10 so that the metal is introduced only by one of the second gas or the vaporized dopant material.

[0038] The above disclosure describes the use of a dopant material containing aluminum as a solid compound in the vaporizer 190 and a second gas containing aluminum, but other metals can also be used. For example, the metal can be gallium. In this embodiment, the solid compound in the vaporizer 190 can be gallium iodide, and the second gas can be an organogallium gas. In another embodiment, the metal can be indium. In this embodiment, the solid compound in the vaporizer 190 can be indium iodide, and the second gas can be an organoindium gas. In another embodiment, the metal can be lanthanum. In this embodiment, the solid compound in the vaporizer 190 can be lanthanum fluoride, and the second gas can be an organolanthanide gas. Other metals can also be used.

[0039] The embodiments described above in this application can have many advantages. First, the generation of an ion source that can operate in multiple modes is advantageous because the same ion source can be used to generate both monovalent and polyvalent ions. Further, combining a vaporizer with a gas containing a solid metal compound and a metal provides additional benefits.

[0040] First, the organoaluminum gas is available in a gas container, enabling long life and easy replacement. Organoaluminum also effectively generates monovalent aluminum ions. Finally, the halogen in the organoaluminum gas also acts as an etchant to prevent aluminum from accumulating on the walls of the arc chamber 100.

[0041] Second, the use of the vaporizer 190 is well known, and the amount of vapor introduced into the arc chamber 100 can be tightly controlled based on the temperature of the vaporizer 190.

[0042] Thus, this ion source can create monovalent or polyvalent ions of a selected species, which species are metals such as aluminum, gallium, indium, lanthanum, etc.

[0043] The present disclosure should not be limited in scope by the specific embodiments described herein. Indeed, various other embodiments and modifications of the present disclosure will be apparent to those skilled in the art from the foregoing description and the accompanying drawings in addition to those described herein. Accordingly, such other embodiments and modifications are intended to be within the scope of the present disclosure. Further, although the present disclosure has been described herein in the context of a particular implementation for a particular purpose in a particular environment, those skilled in the art will appreciate that the usefulness of the present disclosure is not limited to that particular implementation and that the present disclosure can be advantageously 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 indirectly heated cathode ion source comprising: an arc chamber having a plurality of walls; an indirectly heated cathode disposed within the arc chamber; a vaporizer in communication with the arc chamber; a heater for heating a dopant material disposed within the vaporizer; a first valve in communication with the arc chamber and a first gas source; a second valve in communication with the arc chamber and a second gas source; and a controller in communication with the first valve, the second valve, and the heater for operating the indirectly heated cathode ion source in one of a plurality of modes. An indirectly heated cathode ion source.

2. The indirectly heated cathode ion source of claim 1, wherein the plurality of modes includes two single charge modes for generating ions of a species having a single charge and a multi-charge mode for generating ions of the species having two or more charges.

3. The indirectly heated cathode ion source of claim 2, wherein the species includes a metal.

4. The indirectly heated cathode ion source of claim 2, wherein in a first single charge mode, the controller activates the heater, opens the first valve, and closes the second valve.

5. The indirectly heated cathode ion source of claim 2, wherein in a second single charge mode, the controller deactivates the heater and opens the second valve.

6. The indirectly heated cathode ion source of claim 5, wherein in the second single charge mode, the controller opens the first valve.

7. The indirectly heated cathode ion source of claim 2, wherein in the multi-charge mode, the controller activates the heater and opens the second valve.

8. The indirectly heated cathode ion source of claim 1, wherein the dopant material disposed within the vaporizer includes a solid compound containing a metal, and the metal is also a component of a second gas included in the second gas source.

9. The indirectly heated cathode of claim 8, wherein the metal is aluminum and the dopant material disposed within the vaporizer is aluminum chloride.

10. The indirectly heated cathode of claim 8, wherein the metal is aluminum and the dopant material disposed within the vaporizer is aluminum iodide.

11. The indirect heating cathode ion source according to claim 8, wherein the metal is aluminum, the first gas source contains an inert gas, and the second gas source contains dimethylaluminum chloride or trimethylaluminum chloride.

12. A method of operating an indirect heating cathode ion source in a plurality of modes, the indirect heating cathode ion source comprising a controller, an arc chamber, a vaporizer communicating with the arc chamber, and a heater for heating a dopant material in the vaporizer, the method comprising: selecting a desired operating mode; configuring the indirect heating cathode ion source to operate in the desired mode using the controller and comprising For operation in a multi-charge mode, the multi-charge mode is used to generate ions of species having two or more charges, the heater is operated such that the vaporized dopant material containing the metal enters the arc chamber, and the controller allows the flow of the gas containing the metal into the arc chamber. In a first single-charge mode, the first single-charge mode is used to generate ions of the species having a single charge, the controller operates the heater and allows the flow of an inert gas into the arc chamber. For operation in a second single-charge mode, the second single-charge mode is used to generate ions of the species having a single charge, and the controller deactivates the heater and generates a plasma using the gas containing the metal.

13. The method according to claim 12, wherein the metal is aluminum and the dopant material disposed in the vaporizer is aluminum chloride.

14. The method according to claim 12, wherein the metal is aluminum and the dopant material disposed in the vaporizer is aluminum iodide.

15. The method according to claim 12, wherein the metal is aluminum and the gas containing the metal contains DMAC or TMAC.

16. An indirect heating cathode ion source, comprising: an arc chamber having a plurality of walls; a vaporizer communicating with the arc chamber; an indirectly heated cathode disposed in the arc chamber, the indirectly heated cathode being used to generate a plasma in the arc chamber. A controller configured to operate the indirect heating cathode ion source in one of a plurality of modes, wherein in the multi-charge mode, the controller configures the indirect heating cathode ion source such that two sources of metal are used to generate plasma, and the controller An indirect heating cathode ion source comprising. **Claim 17** The indirect heating cathode ion source according to claim 16, wherein the metal is aluminum, the material disposed in the vaporizer contains aluminum chloride, and a gas containing aluminum is introduced into the arc chamber when operating in the multi-charge mode. **Claim 18** The indirect heating cathode ion source according to claim 16, wherein the metal is aluminum, the material disposed in the vaporizer contains aluminum iodide, and a gas containing aluminum is introduced into the arc chamber when operating in the multi-charge mode. **Claim 19** The indirect heating cathode ion source according to claim 16, wherein in the single-charge mode, only one of the two sources is introduced into the arc chamber.

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