TWI818252B - Indirectly heated cathode ion source - Google Patents

Abstract

An ion source having improved life is disclosed. In certain embodiments, the ion source is an IHC ion source comprising a chamber, having a plurality of electrically conductive walls, having a cathode which is electrically connected to the walls of the ion source. Electrodes are disposed on one or more walls of the ion source. A bias voltage is applied to at least one of the electrodes, relative to the walls of the chamber. In certain embodiments, fewer positive ions are attracted to the cathode, reducing the amount of sputtering experienced by the cathode. Advantageously, the life of the cathode is improved using this technique. In another embodiment, the ion source comprises a Bernas ion source comprising a chamber having a filament with one lead of the filament connected to the walls of the ion source.

Description

Indirectly heated cathode ion source

The present invention relates to an ion source, and more particularly to an ion source having a cathode electrically connected to a wall of a chamber to improve the life of the ion source.

Various types of ion sources can be used to generate ions used in semiconductor processing equipment. For example, a Berners ion source works by passing an electric current through a filament placed in a chamber. The filaments emit electrons to excite gas that is introduced into the chamber. Magnetic fields can be used to constrain the paths of electrons. In certain embodiments, electrodes are also disposed on one or more walls of the chamber. These electrodes can be biased positively or negatively to control the position of ions and electrons, thereby increasing the ion density near the center of the chamber. An extraction opening is provided along the other side and close to the center of the chamber through which ions can be extracted.

One issue associated with Berners ion sources is filament lifetime. Because the filament is exposed to the chamber, the filament is subject to sputtering and other phenomena that shorten filament life. In some embodiments, the lifetime of the Berners ion source depends on the lifetime of the filament.

The second type of ion source is the indirectly heated cathode (IHC) ion source. Indirectly heated cathode ion sources work by supplying electrical current to a filament positioned behind the cathode. The filament emits thermal electrons, which accelerate toward the cathode and heat it, which in turn causes the cathode to emit electrons into the chamber of the ion source. Because the filament is protected by the cathode, its lifetime is extended relative to a Berners ion source. The cathode is disposed at one end of the chamber. A repeller is usually provided at one end of the chamber opposite the cathode. The cathode and repeller can be biased to repel electrons, directing them back toward the center of the chamber. In some embodiments, magnetic fields are used to further confine electrons within the chamber.

In certain embodiments, electrodes are also disposed on one or more side walls of the chamber. These electrodes can be biased positively or negatively to control the position of ions and electrons, thereby increasing the ion density near the center of the chamber. An extraction opening is provided along the other side and close to the center of the chamber through which ions can be extracted.

One problem associated with indirectly heated cathode ion sources is that the cathode can have a limited life. The cathode is bombarded by electrons on its back side and by positively charged ions on its front side. Ion bombardment can cause sputtering, causing corrosion of the cathode. In many embodiments, the life of the indirectly heated cathode ion source depends on the life of the cathode. In certain embodiments, chemical vapor deposition from the plasma can electrically connect the negatively charged cathode to the grounded wall of the ion source, causing ion source malfunction.

Therefore, an ion source with increased lifetime may be beneficial. Additionally, it would be advantageous if the ion source experienced less sputtering on the components used to generate electrons.

The present invention discloses an ion source with improved lifetime. In some embodiments, the ion source is an indirectly heated cathode ion source, the indirectly heated cathode ion source includes a chamber having a plurality of conductive walls, the indirectly heated cathode ion source has A cathode electrically connected to the wall of the ion source. Electrodes are provided on one or more walls of the ion source. At least one of the electrodes is biased relative to the wall of the chamber. In certain embodiments, fewer positive ions are attracted to the cathode, thereby reducing the amount of sputtering the cathode experiences. Advantageously, using this technique will improve the life of the cathode. In another embodiment, the ion source includes a Berners ion source including a chamber having a filament with one side connected to a wall of the ion source.

According to one embodiment, an indirectly heated cathode ion source is disclosed. The indirectly heated cathode ion source includes: a chamber including a plurality of conductive walls into which gas is introduced; a cathode disposed on one end of the chamber; a filament disposed behind the cathode; a magnetic field passing through the chamber; a top wall having an extraction opening; and an electrode disposed in the chamber along a wall of the chamber; wherein a voltage is applied to the electrode relative to the chamber, and The cathode is electrically connected to the chamber. In some embodiments, the electrodes are disposed on sidewalls parallel to the magnetic field. In yet another embodiment, a second electrode is provided on a side wall opposite to the electrode, wherein the electric field and the magnetic field between the electrode and the second electrode are perpendicular to each other. In certain embodiments, the electrodes are disposed on the top wall on opposite sides of the extraction opening.

In a second embodiment, an indirectly heated cathode ion source is disclosed. The indirectly heated cathode ion source includes: a chamber including a plurality of conductive walls into which gas is introduced; a cathode disposed on one wall of the chamber; and a filament disposed behind the cathode. ; A magnetic field passing through the chamber; and an electrode disposed in the chamber on a wall opposite to the cathode; wherein the cathode is disposed on a wall parallel to the magnetic field. In certain embodiments, the cathode is electrically connected to the chamber. In certain embodiments, the electrode is positively biased relative to the chamber.

In a third embodiment, a Berners ion source is disclosed. The Berners ion source includes: a chamber including a plurality of conductive walls into which gas is introduced; a filament disposed on one end of the chamber; a magnetic field passing through the chamber; and a top a wall having an extraction opening; and an electrode disposed along the wall of the chamber; wherein a voltage is applied to the electrode relative to the chamber and one lead of the filament is electrically connected to the chamber. In some embodiments, the electrodes are disposed on sidewalls parallel to the magnetic field. In some embodiments, a second electrode is disposed on a side wall opposite the electrode, wherein the electric field and the magnetic field between the electrode and the second electrode are perpendicular to each other.

In order to make the above-mentioned features and advantages of the present invention more obvious and easy to understand, embodiments are given below and described in detail with reference to the accompanying drawings.

As mentioned above, ion sources can be susceptible to shortened lifetimes due to sputtering effects, particularly those that occur on components used to generate electrons. Often, over time, these components fail. In some embodiments, failure of an indirectly heated cathode ion source is caused by an electrical short between the cathode and the walls of the ion source, or between the repulsion and the walls of the ion source. Similarly, Berners ion sources can be susceptible to lifetime shortening due to sputtering effects on the filaments.

Figure 1 shows an indirectly heated cathode ion source 10 that overcomes these problems. FIG. 4 is a cross-sectional view of the indirectly heated cathode ion source 10 . The indirectly heated cathode ion source 10 includes a chamber 100 including two opposite ends and side walls 101 connected to the ends. The chamber 100 also includes a bottom wall 102 and a top wall 103 . The various walls of the chamber may be constructed of electrically conductive material and may be in electrical communication with each other. In the chamber 100, a cathode 110 is disposed at a first end 104 of the chamber 100. A filament 160 is provided behind the cathode 110 . Filament 160 communicates with filament power source 165. Filament power supply 165 is configured to pass electrical current through filament 160 such that filament 160 emits hot electrons. Cathode bias power supply 115 negatively biases filament 160 relative to cathode 110 so these hot electrons accelerate from filament 160 toward cathode 110 and heat cathode 110 as they impact the backside of cathode 110 . Cathode bias power supply 115 may bias filament 160 such that filament 160 has a voltage that is, for example, between negative 200V and negative 1500V relative to the voltage of cathode 110 . The cathode 110 then emits hot electrons into the chamber 100 on its front side.

Therefore, filament power supply 165 supplies current to filament 160 . Cathode bias power supply 115 biases filament 160 so that filament 160 has a more negative value than cathode 110 , thereby causing electrons to be attracted from filament 160 toward cathode 110 . Additionally, cathode 110 is electrically connected to chamber 100 to be at the same voltage as the walls of chamber 100 . In some embodiments, chamber 100 is connected to electrical ground.

In this embodiment, in the chamber 100, a repellent electrode 120 is provided on the second end 105 of the chamber 100 opposite the cathode 110. The repeller 120 can communicate with the repeller power supply 125 . As the name suggests, repellent 120 is used to repel electrons emitted from cathode 110 back toward the center of chamber 100 . For example, the repeller 120 may be negatively biased relative to the chamber 100 to repel electrons. For example, repeller power supply 125 may have an output in the range of 0V to -150V, although other voltages may be used. In some embodiments, repeller 120 is biased between 0V and -150V relative to chamber 100 . In some embodiments, repeller 120 may float relative to chamber 100 . In other words, when floating, repeller 120 is not electrically connected to repeller power supply 125 or chamber 100 . In this embodiment, the voltage of the repellent 120 tends to drift closer to the voltage of the cathode 110 .

In certain embodiments, magnetic field 190 is generated in chamber 100 . This magnetic field is designed to confine electrons in one direction. The magnetic field 190 is generally distributed parallel to the side wall 101 from the first end 104 to the second end 105 . For example, electrons may be confined in columns parallel to the direction from cathode 110 to repeller 120 (ie, the y-direction). Therefore, the electron does not experience any electromagnetic force to move in the y direction. However, electrons moving in other directions can experience electromagnetic forces.

In the embodiment shown in FIG. 1 , electrodes 130A and 130B may be provided on the side wall 101 of the chamber 100 so that the electrodes 130A and 130B are located in the chamber 100 . Electrodes 130A, 130B may be biased by a power source. In some embodiments, electrodes 130A, 130B may be in communication with a common power source. However, in other embodiments, to maximize the flexibility and ability to adjust the output of the indirectly heated cathode ion source 10, the electrodes 130A, 130B may communicate with respective electrode power supplies 135A, 135B, respectively.

Like repeller power supply 125 , electrode power supplies 135A, 135B are used to bias electrodes 130A, 130B relative to chamber 100 . In certain embodiments, electrode power supply 135A, 135B may positively or negatively bias electrodes 130A, 130B relative to chamber 100. In certain embodiments, at least one of electrodes 130A, 130B may be biased relative to chamber 100 between 40 volts and 500 volts.

Each of the cathode 110, the repeller 120, and the electrodes 130A, 130B is made of a conductive material such as metal.

An extraction opening 140 may be provided on the other side of the chamber 100 referred to as the top wall 103 . In Figure 1, the extraction opening 140 is provided on a side parallel to the X-Y plane (parallel to the page). In addition, although not shown in the figure, the indirectly heated cathode ion source 10 further includes a gas inlet through which gas to be ionized is introduced into the chamber 100 .

Controller 180 may communicate with one or more of the power supplies such that the voltage or current supplied by the power supplies may be modified. Controller 180 may include a processing unit such as a microcontroller, a personal computer, a special purpose controller, or another suitable processing unit. Controller 180 may also include non-transitory memory elements, such as semiconductor memory, magnetic memory, or another suitable memory. This non-transitory memory element may contain instructions and other data that enable controller 180 to perform the functions described herein.

Controller 180 may be used to select the initial voltage or current to be supplied by cathode bias power supply 115, filament power supply 165, electrode power supplies 135A, 135B, and repeller power supply 125. This initial voltage may be based on the type of gas being used, or on the type of ions to be extracted from the indirectly heated cathode ion source 10 . Additionally, in some embodiments, the controller may also monitor the current of the extracted ion beam. Based on the monitored extraction current, the controller 180 may vary at least the current supplied by the filament power supply 165 to obtain the desired extraction current.

During operation, filament power supply 165 passes electrical current through filament 160, which causes filament 160 to emit thermionic electrons. These electrons strike the back of cathode 110 , which may have a greater positive value than filament 160 , causing cathode 110 to heat, which in turn causes cathode 110 to emit electrons into chamber 100 . These electrons collide with gas molecules fed into the chamber 100 via the gas inlet. These collisions generate positive ions, forming a plasma 150 . Plasma 150 may be confined and manipulated by the electric field generated by repellent 120 and electrodes 130A, 130B. Additionally, in some embodiments, electrons and positive ions may be bound by the magnetic field 190 to some extent. In some embodiments, plasma 150 is confined near the center of chamber 100, close to extraction opening 140.

Because the cathode 110 is not biased relative to the chamber 100, fewer positive ions are attracted to the cathode 110 and these ions have lower energy, so they sputter less frequently. Therefore, the amount of sputtering can be reduced and the life of the cathode 110 can be extended. Additionally, even when sputtering is present, the risk of electrical shorting is eliminated when the cathode 110 and the walls of the chamber 100 are at the same voltage.

In this embodiment, electrons may be attracted to electrode 130A which is positively biased relative to chamber 100. However, electrons need to overcome electromagnetic forces to traverse magnetic fields190. Therefore, the choice of the strength of magnetic field 190 and the positive voltage applied by electrode power supply 135A determines the speed and energy of electrons as they are attracted toward electrode 130A. A stronger magnetic field with a low forward bias applied to electrode 130A will reduce the number of electrons able to traverse magnetic field 190 . Conversely, a weaker magnetic field coupled with a larger bias voltage applied to electrode 130A will enable more electrons moving at higher speeds toward electrode 130A.

Therefore, by changing the strength of the magnetic field 190 and the voltage applied by the electrode power supply 135A, the speed and energy of the electrons can be manipulated. This makes the indirectly heated cathode ion source 10 suitable for multiply charged ions, monomers and ionized molecules.

For example, for singly charged ions, a rich gas can be used with a weak magnetic field. In some embodiments, the first voltage may be applied by electrode power supply 135A. For multiply charged ions, a lean gas can be used in conjunction with a strong magnetic field. In this embodiment, the voltage applied to electrode 130A may be greater than the first voltage. Stronger magnetic fields allow more collisions to occur, creating multiply charged species.

FIG. 1 shows a diagram in which cathode 110 is electrically connected to chamber 100 and repulser 120 and electrodes 130A, 130B are independently biased relative to chamber 100 using repulser power supply 125 and electrode power supplies 135A, 135B, respectively. An embodiment of an indirectly heated cathode ion source 10. Figure 2 shows an indirectly heated cathode ion source 11 according to another embodiment. Similar elements are assigned the same reference designator. The indirectly heated cathode ion source 11 has a cathode 110 and a repeller 120 , both of which are electrically connected to the chamber 100 . Additionally, one of the electrodes 130B is also electrically connected to the chamber 100 . In other words, the cathode 110, the repeller 120, the electrode 130B and the wall of the chamber 100 are all at the same voltage. Therefore, the electrode power supply 135B and the repeller power supply 125 can be omitted.

In this embodiment, only electrode 130A is biased relative to chamber 100 . Electrode 130A may be positively biased relative to chamber 100 between 40 volts and 500 volts. Therefore, the electric field within chamber 100 is generated only by electrode 130A. In addition, the electric field between electrode 130A and electrode 130B is perpendicular to magnetic field 190 . Specifically, the magnetic field 190 is in the Y direction, and the electric field between electrode 130A and electrode 130B is in the X direction. Therefore, the electromagnetic force is mainly located in the Z direction. In some embodiments, the electromagnetic force is directed upward toward the extraction opening 140 .

FIG. 3 shows changes of the indirectly heated cathode ion source 11 shown in FIG. 2 . In FIG. 3 , the repellent electrode of the indirectly heated cathode ion source 12 is omitted. Since the repulser 120 shown in FIG. 2 is at the same voltage as the chamber 100 , omitting the repulser 120 in FIG. 3 does not change the operation of the indirectly heated cathode ion source 12 . In other words, in both embodiments, the second end 105 opposite the cathode 110 is biased to the same voltage as the wall of the chamber 100 .

FIG. 4 shows a cross-sectional view of the indirectly heated cathode ion source 10 taken along line AA shown in FIG. 1 . In this figure, the cathode 110 is shown resting against the first end 104 of the indirectly heated cathode ion source 10 . Electrodes 130A and 130B are shown on two opposing side walls 101 of the chamber 100 . Magnetic field 190 is shown pointing away from the page in the Y direction. In some embodiments, electrodes 130A, 130B may be separated from sidewall 101 of chamber 100 using insulators 133A, 133B, respectively. Electrical connections from the electrode power sources 135A, 135B to the electrodes 130A, 130B may be made by passing conductive material from outside the chamber 100 through the insulators 133A, 133B to the respective electrodes 130A, 130B. In certain embodiments, electrode 130B may be in electrical communication with chamber 100. In these embodiments, insulator 133B may not be used and electrode 130B may be positioned against sidewall 101 . Additionally, in some embodiments, since the electrode 130B is at the same voltage as the sidewall 101, the electrode 130B may be omitted.

Additionally, in some embodiments, insulators 133A, 133B are not used. Rather, if electrode 130A is biased relative to chamber 100 , electrode 130A may be spaced apart from the walls of chamber 100 .

Although FIGS. 1-4 each show electrodes 130A, 130B disposed along opposing side walls 101 of chamber 100, other embodiments are possible. Figure 5 illustrates such an embodiment. FIG. 5 is a cross-sectional view of the indirectly heated cathode ion source 14. Except for the location of electrode 230, this indirectly heated cathode ion source 14 is similar in most respects to other indirectly heated cathode ion sources. In this embodiment, the electrode 230 is provided on the top wall 103 of the chamber 100 in which the extraction opening 140 is provided. Electrode 230 may be insulated from top wall 103 using insulator 233. In some embodiments, the electrode 230 may be disposed within the chamber 100 and surround the entire extraction opening 140 . In other embodiments, electrodes 230 may be disposed on opposing side walls of extraction opening 140 within chamber 100 . Therefore, the electric field is strongest near the extraction opening 140. This configuration can increase the ion beam current or energy relative to the configuration shown in Figure 4.

Figure 6 shows another embodiment of an indirectly heated cathode ion source 15. In this embodiment, the cathode 210 and the filament 160 have been moved from one end of the indirectly heated cathode ion source 15 to the side wall 101 opposite the electrode 130A. In other words, the cathode 210 is disposed on the side wall 101 parallel to the magnetic field 190 . Therefore, unlike the previous embodiment, electrons emitted from cathode 210 immediately encounter magnetic field 190. Therefore, the voltage applied to electrode 130A by electrode power supply 135A may be large enough to attract emitted electrons across magnetic field 190 . Alternatively or additionally, magnetic field 190 may be relatively weak to cause electrons to traverse the field toward electrode 130A. In this embodiment, the two ends of the indirectly heated cathode ion source 15 that usually includes a cathode and a repeller may not include a cathode and a repeller.

The above-described embodiments in the present application may have many advantages. First, because the electrodes are electrically connected to the chamber, there is no short circuit problem between the cathode and the chamber wall, thus eliminating a common cause of failure in indirectly heated cathode ion sources. Second, because the cathode is electrically connected to the chamber, fewer positive ions are attracted to the cathode, thereby reducing the amount of sputtering the cathode experiences. Third, compared to traditional indirectly heated cathode ion sources, the source power required to achieve equivalent extraction current is reduced, which also contributes to longer ion source life. In addition, ion sources according to embodiments described herein are equally well suited for multiply charged species, monomeric species, and molecular species. Experimental data have shown that the ion source described herein provides up to 40% of the beam current at a minimum of 30% of the source power.

The concept of maintaining the components used to generate electrons at or near the chamber voltage can be applied to other ion sources as well. Figure 7 illustrates a Berners ion source 300 according to one embodiment.

Like the indirectly heated cathode ion source shown in Figure 3, Berners ion source 300 includes a chamber 310 having a plurality of conductive walls. Berners ion source 300 may or may not have a repulsive reject. In addition, electrodes 330A, 330B may be disposed on opposite side walls 301. Berners ion source 300 includes filament 360 in communication with filament power supply 365 . The positive terminal of filament power supply 365 communicates with one lead of filament 360 and also with the wall of chamber 310 . The negative terminal of filament power supply 365 communicates with the other lead of filament 360. The voltage across the leads of filament 360 may be less than 10 volts. Filament 360 may be disposed at first end 304 of chamber 310 .

The magnetic field 390 may also be applied from the first end 304 of the Berners ion source 300 toward the second end 305 opposite the first end 304 . As with the indirectly heated cathode ion source described above, the electrons can be constrained to some extent into columns oriented in the y direction. Electrode 330A may be positively biased relative to chamber 310 and may be disposed on sidewall 301 .

During operation, filament power source 365 passes electrical current through filament 360, which causes filament 360 to emit hot electrons. These electrons collide with gas molecules fed into the chamber 310 via the gas inlet. These collisions generate positive ions, forming a plasma 350 . Plasma 350 may be confined and manipulated by the electric field generated by electrodes 330A, 330B. Like an indirectly heated cathode ion source, electrode 330A can communicate with electrode power source 335A. Additionally, in some embodiments, electrons and positive ions may be bound by the magnetic field 390 to some extent. In some embodiments, plasma 350 is confined near the center of chamber 310, close to extraction opening 340.

The function of controller 180 may be as described above.

Because one lead of filament 360 is electrically connected to chamber 310, fewer positive ions are attracted to filament 360. Therefore, the amount of sputtering can be reduced and the life of filament 360 can be extended.

Although FIG. 7 illustrates Berners ion source 300 with electrode 330B electrically connected to chamber 310 without a repeller, other embodiments are possible. For example, the cathode 110, cathode bias power supply 115, filament 160 and filament power supply 165 shown in FIGS. 1 and 2 may be replaced by the filament 360 and filament power supply 365 shown in FIG. 7 . In other words, in some embodiments, a Berners ion source may include a repeller grounded to the chamber, or a repeller in communication with a repeller power source. Additionally, in some embodiments, electrode 330B can communicate with an electrode power source.

Additionally, the Berners ion source 300 shown in FIG. 7 can be modified to position the electrode 330A on the top wall similar to the position of the electrode 230 shown in FIG. 5 .

As with the indirectly heated cathode ion source described above, the Berners ion source embodiment described above in this application may have many advantages. For example, because one lead of the filament is electrically connected to the chamber, fewer positive ions are attracted to the filament, thereby reducing the amount of sputtering that the filament experiences. This reduction in sputtering extends the life of the filament.

Although the present invention has been disclosed above through embodiments, they are not intended to limit the present invention. Anyone with ordinary knowledge in the technical field may make some modifications and modifications without departing from the spirit and scope of the present invention. Therefore, The protection scope of the present invention shall be determined by the appended patent application scope.

10, 11, 12, 14, 15: Indirectly heated cathode ion source 100, 310: Chamber 101, 301: Side wall 102: Bottom wall 103: Top wall 104, 304: first end 105, 305: second end 110, 210: cathode 115:Cathode bias power supply 120:Rejection 125: Repulsion power supply 130A, 130B, 230, 330A, 330B: Electrode 133A, 133B, 233: Insulator 135A, 135 B, 335A: Electrode power supply 140, 340: Extract openings 150, 350: Plasma 160, 360: filament 165, 365: Filament power supply 180:Controller 190, 390: Magnetic field 300: Berners ion source X, Y, Z: direction

Figure 1 is an indirectly heated cathode (IHC) ion source according to one embodiment. Figure 2 is an indirectly heated cathode ion source according to another embodiment. Figure 3 is an indirectly heated cathode ion source according to another embodiment. FIG. 4 is a cross-sectional view of the indirectly heated cathode ion source shown in FIG. 1 . Figure 5 is a cross-sectional view of an indirectly heated cathode ion source according to another embodiment. Figure 6 is an indirectly heated cathode ion source according to another embodiment. Figure 7 is an ion source according to another embodiment.

10:Indirectly heated cathode ion source

100: Chamber

101:Side wall

104:First end

105:Second end

110:Cathode

115:Cathode bias power supply

120:Rejection

125: Repulsion power supply

130A, 130B: Electrode

135A, 135B: Electrode power supply

140:Extract opening

150:Plasma

160: filament

165: Filament power supply

180:Controller

190:Magnetic field

X, Y, Z: direction

Claims (21)

An indirectly heated cathode ion source includes: a chamber including two opposite ends and two side walls connecting the opposite ends; a cathode arranged on one of the opposite ends of the chamber; a wire disposed behind the cathode; a magnetic field passing through the chamber and parallel to the two side walls; and an electrode disposed in the chamber and disposed in the two side walls of the chamber The first one; wherein a voltage is applied to the electrode such that the electrode is electrically biased relative to the chamber, and the cathode is electrically connected to the chamber. The indirectly heated cathode ion source as described in item 1 of the patent application, wherein the repellent electrode is disposed on the second of the two opposite ends of the chamber. For the indirectly heated cathode ion source described in item 2 of the patent application, the repellent electrode is electrically connected to the chamber. For example, in the indirectly heated cathode ion source described in item 1 of the patent application, the repellent electrode is not disposed in the chamber. For example, in the indirectly heated cathode ion source described in item 1 of the patent application, a positive bias voltage is applied to the electrode relative to the chamber. The indirectly heated cathode ion source as described in item 1 of the patent application, wherein the two opposite ends extend in the height direction and the width direction, and the two side walls extend in the height direction and the length direction, The electromagnetic force generated by the magnetic field and electric field in the chamber is in the height direction. An indirectly heated cathode ion source includes: a chamber including two opposite ends and two side walls connecting the opposite ends; a cathode arranged on one of the opposite ends of the chamber; a wire disposed behind the cathode; a first electrode disposed in the chamber and on the first of the two side walls of the chamber; and a second electrode disposed in the chamber and is disposed on the second of the two side walls of the chamber; wherein a voltage is applied to the first electrode such that the first electrode is electrically biased relative to the chamber, and the The cathode is electrically connected to the chamber. The indirectly heated cathode ion source as described in claim 7, wherein the second electrode is electrically biased relative to the chamber. For the indirectly heated cathode ion source described in claim 8, the first electrode and the second electrode are biased by a common power supply. For the indirectly heated cathode ion source described in claim 8, the first electrode and the second electrode are biased by two power supplies. The indirectly heated cathode ion source as described in item 7 of the patent application, wherein the repellent electrode is disposed on the second of the two opposite ends of the chamber. As described in claim 11 of the patent application, the indirectly heated cathode ion source is characterized in that the repellent electrode is electrically connected to the chamber. For the indirectly heated cathode ion source described in item 7 of the patent application, the repellent electrode is not disposed in the chamber. An indirectly heated cathode ion source includes: a chamber including two opposite ends and two side walls, the two side walls connecting the two opposite ends; a cathode disposed on the opposite two sides of the chamber One end of the end is electrically connected to the chamber; a filament is disposed behind the cathode; a magnetic field passes through the chamber in the Y direction, where the Y direction is from the two opposite ends. The direction from one of the two opposite ends to the other of the two opposite ends; and a first electrode disposed in the chamber and disposed on the first of the two side walls of the chamber; wherein The first electrode applies a voltage such that the first electrode is electrically biased relative to the chamber to generate an electric field between the two side walls, and the electric field is in the X direction and in the Z direction Electromagnetic force is generated on, and the Z direction is perpendicular to the X direction and the Y direction. The indirectly heated cathode ion source as described in claim 14 of the patent application, wherein the repellent electrode is disposed on the second of the two opposite ends of the chamber. For the indirectly heated cathode ion source described in claim 15 of the patent application, the repellent electrode is electrically connected to the chamber. For the indirectly heated cathode ion source described in item 14 of the patent application, the repellent electrode is not disposed in the chamber. The indirectly heated cathode ion source as described in item 14 of the patent application further includes a second electrode, which is disposed in the chamber and disposed on the second of the two side walls of the chamber. The indirectly heated cathode ion source as claimed in claim 18, wherein the second electrode is electrically biased relative to the chamber. For the indirectly heated cathode ion source described in claim 19, the first electrode and the second electrode are biased by a common power supply. For the indirectly heated cathode ion source described in claim 19, the first electrode and the second electrode are biased by two power supplies.

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