Ion source with multiple bias electrodes
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- AXCELIS TECHNOLOGIES INC
- Filing Date
- 2022-05-11
- Publication Date
- 2026-08-03
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Figure 0007899222000001 
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Abstract
Description
Detailed description of the invention
[0001] [Technical field] This invention generally relates to ion implantation systems. More specifically, it relates to an ion source having improved current, efficiency, and lifetime by utilizing multiple bias electrodes.
[0002] [background] In the manufacturing of semiconductor devices, ion implantation is used to dopane semiconductors with impurities. In many cases, ion implantation systems are used to dopage workpieces, such as semiconductor wafers, with ions derived from an ion beam. This can result in n-type or p-type material doping, or the formation of passivation layers during integrated circuit manufacturing. To generate semiconductor materials during integrated circuit manufacturing, such beam treatment is often used to selectively implant specific dopant material impurities into the wafer at a predetermined energy level and controlled concentration. When an ion implantation system is used to dopane semiconductor wafers, it implants selected ion species into the workpiece to produce the desired exogenous material. For example, implanting ions generated from source materials such as antimony, arsenic, or phosphorus produces an "n-type" exogenous material wafer. On the other hand, "p-type" exogenous material wafers are often produced from ions generated using source materials such as boron, gallium, or indium.
[0003] A typical ion implantation system includes an ion source, an ion extraction device, a mass spectrometer, a beam transport device, and a wafer processing device. The ion source generates ions of a desired atomic or molecular dopant species. These ions are extracted from the source by an extraction system (typically a set of electrodes). The extraction system energizes the flow of ions originating from the source, forming an ion beam. The desired ions are separated from the ion beam inside a mass spectrometer (typically a magnetic dipole that performs mass dispersion or separation of the extracted ion beam). A beam transport device (typically a vacuum system including a series of focusing devices) transports the ion beam to the wafer processing device while maintaining or improving the desired properties of the ion beam. Finally, the semiconductor wafer is transported in and out of the wafer processing device via a wafer handling system. The wafer handling system may include one or more robotic arms to position the wafer to be processed in front of the ion beam and to remove the processed wafer from the ion implantation system.
[0004] An ion source (generally referred to as an arc ion source) generates an ion beam used in an injection device. The ion source may include a heated filament cathode to generate ions that are shaped into an ion beam suitable for wafer processing. For example, U.S. Patent No. 5,497,006 by Sferlazzo et al. discloses an ion source having a cathode. The cathode is supported by a base, positioned relative to a gas containment chamber, and emits ionizing electrons toward the interior of the gas containment chamber. The cathode of Sferlazzo et al. is a tubular conductor having an end cap that partially extends toward the interior of the gas containment chamber. The filament is supported inside the tubular body and emits electrons that heat the end cap by electron collision. In this way, the filament thermionically emits ionizing electrons toward the interior of the gas containment chamber.
[0005] Traditionally, the filament is located on one side of the chamber. Many widely used ion sources implement an indirectly heated cathode (IHC). In this case, a tungsten cap is positioned above the filament, and the filament heats the cap. At the same time, the cap protects the filament to increase the lifespan of the ion source. However, the cap or cathode is sputtered and removed over time. For this reason, the thickness of the cap is set to be large. In this case, the filament is heated to a high temperature to emit a considerable amount of electrons. Therefore, the cap in this example behaves similarly to the filament for emitting electrons, but its significantly thicker design allows for a longer lifespan.
[0006] To increase the beam current of an ion beam drawn in a higher charge state, one or more bias electrodes are further provided within the ion source chamber. Various configurations of ion source chambers having bias electrodes have been provided for some time. Such configurations are described, for example, in U.S. Patent No. 8,330,127 by Low et al., U.S. Patent No. 9,691,584 by Tieger et al., and U.S. Patent Publication No. 2018 / 0254166 by Kawaguchi. However, these conventional arc chambers typically provide one or more of several bias electrodes that are grounded to the arc chamber.
[0007] In the absence of a bias electrode, the cathode is negatively biased to the arc chamber. Therefore, electrons thermally emitted by the cathode are driven from the negative potential into the arc chamber. By adding a bias electrode, these electrons can be attracted by a positive voltage. Furthermore, the cathode's lifespan can be increased by grounding the cathode and biasing only the bias electrode. However, even in this case, at least one of the multiple bias electrodes is grounded in the conventional system.
[0008] [overview] The ion source is a key component of an ion implantation system. Therefore, various metrics related to the ion implantation system, such as throughput, uptime, glitch rate, and desired implantation parameters, affect the performance of the ion source. This disclosure provides multiple electrodes independently biased within the ion source. This facilitates improvements to other parameters related to the ion source, thereby advantageously increasing the lifetime of the ion source, while achieving increased beam current in response to multiple charged ions (multivalent ions).
[0009] Therefore, this disclosure provides systems and apparatus for increasing the efficiency and ion beam current generated by an ion source. This disclosure provides at least two electrodes located inside the arc chamber of an ion source. At least two electrodes are individually electrically biased. The ion source of this disclosure is particularly beneficial for multiple charged ion species because it can provide an ion beam current greater than twice that of conventional ion sources. In addition, the ion source of this disclosure provides an indirectly heated cathode with reduced noise and so-called glitch rate compared to conventional indirectly heated cathode (IHC) ion sources. Thus, the ion source of this disclosure can provide a balance between the desired beam current associated with the ion source and an increased lifetime compared to conventional IHC ion sources.
[0010] Therefore, to provide a basic understanding of several aspects of the present invention, a simplified summary of this disclosure is presented below. This summary is not a comprehensive overview of the invention. This summary is not intended to identify any important elements of the invention, nor to define its scope. The purpose of this summary is to present several concepts of the invention in a simplified form as an introduction to the detailed description that follows.
[0011] According to one aspect of the present disclosure, an ion source is provided. The ion source comprises an arc chamber having a first end and a second end located opposite to the first end. An opening plate substantially encloses the chamber volume by being operably connected to the arc chamber. The opening plate has a drawout opening located between the first and second ends of the arc chamber. A cathode is located in the chamber volume in close proximity to the first end of the arc chamber. A repeller (e.g., an anti-cathode) is located in the chamber volume in close proximity to the second end of the arc chamber. For example, the cathode may include an indirectly heated cathode comprising a heater filament and a cap. The heater filament is electrically connected to a heater power supply configured to selectively energize the cap to heat the cap.
[0012] For example, the first bias electrode is positioned on the first side of the extraction opening within the chamber space. When viewed from the first end, the first bias electrode is approximately U-shaped (generally U-shaped). Furthermore, the second bias electrode is positioned on the second side of the extraction opening within the chamber space. When viewed from the first end, the second bias electrode is approximately U-shaped. For example, the first and second bias electrodes are separated by a first distance in a first region proximal to the extraction opening. Furthermore, the first and second bias electrodes are separated by a second distance in a second region distal to the extraction opening.
[0013] Furthermore, for example, the electrode power supply is electrically connected to the first bias electrode and the second bias electrode. The electrode power supply is configured to supply a first positive voltage to the first bias electrode and a second positive voltage to the second bias electrode. For example, the second positive voltage differs from the first positive voltage by a predetermined bias difference. For example, the predetermined bias difference is on the order of approximately 10 volts.
[0014] In one example, the first and second bias electrodes extend for a predetermined length between their respective positions adjacent to the first and second ends of the arc chamber. In another example, when viewed from the first end of the arc chamber, the first and second bias electrodes have an arched shape.
[0015] In another example, the first distance between the first and second bias electrodes is greater than the second distance. For example, the first distance is approximately twice the second distance. In yet another example, the first distance is greater than the width of the drawout opening.
[0016] In another example, each of the first and second bias electrodes has a bevel that defines a first distance. Each bevel is associated with a line extending from the respective nearest edge of the extraction opening toward the respective first and second electrodes.
[0017] In another example, the arc chamber further includes a gas hole. The gas hole is defined in the wall of the arc chamber. For example, the gas hole is located between the first and second ends of the arc chamber, adjacent to a second region. The gas hole is fluidly connected to a gas source.
[0018] In another example, the electrode power supply includes a first power supply and a second power supply. For example, the first power supply is configured to supply a first positive voltage to the first bias electrode. The second power supply is configured to supply a second positive voltage to the second bias electrode. In another example, a resistive element is electrically connected between the electrode power supply and the second bias electrode. The resistance of the resistive element determines a predetermined bias difference. For example, the resistive element may include a variable resistor having selectively variable resistance.
[0019] For example, each of the first bias electrode and the second bias electrode may have a plate supported by one or more rods. The one or more rods extend through the wall of the arc chamber. For example, one or more rods are clamped to the respective electrode clamps. Each clamp, one or more rods, and plate are electrically insulated from the arc chamber.
[0020] In another present embodiment, an ion source is provided. The arc chamber has a first arc chamber wall extending from a first end to a second end of the arc chamber. For example, the first wall has a drawout opening defined within the first wall. The drawout opening is located between the first and second ends of the arc chamber. For example, an indirect heating cathode is located close to the first end of the arc chamber. The indirect heating cathode comprises a heater filament and a cap. The heater filament is configured to receive power to heat the cap.
[0021] For example, the first bias electrode is positioned on the first side of the extraction opening, between the first and second ends of the arc chamber. When viewed from the first end, the first bias electrode is roughly U-shaped. Furthermore, the second bias electrode is positioned on the second side of the extraction opening, between the first and second ends of the arc chamber. When viewed from the first end, the second bias electrode is roughly U-shaped. For example, a resistive element is electrically connected between the first and second bias electrodes. The resistance of the resistive element determines a predetermined bias difference between the first and second bias electrodes. The predetermined bias difference is, for example, on the order of approximately 10 volts.
[0022] For example, the first bias electrode and the second bias electrode are separated by a first distance in the first region proximal to the extraction opening, and by a second distance in the second region distal to the extraction opening. The first distance is greater than the second distance.
[0023] In yet another example, an electrode power supply is electrically connected to a first bias electrode and a second bias electrode. The electrode power supply is configured to supply a first positive voltage to the first bias electrode and a second positive voltage to the second bias electrode. The second positive voltage is different from the first positive voltage by a predetermined bias difference.
[0024] In another aspect, a method for increasing the beam current in an indirectly heated cathode (IHC) ion source is provided. The method includes, for example, electrically biasing an indirectly heated cathode disposed inside an arc chamber. The indirectly heated cathode is biased with respect to a first arc chamber wall and a second arc chamber wall that face each other. The first arc chamber wall includes an extraction opening disposed between a first end and a second end of the arc chamber. The first bias electrode is electrically biased with respect to the second bias electrode by a predetermined bias difference. The first bias electrode and the second bias electrode are disposed between the first end and the second end of the arc chamber. The first bias electrode and the second bias electrode are separated by a first gap proximate to the first arc chamber wall and a second gap proximate to the second arc chamber wall. Further, an ion beam is extracted through the extraction opening. The predetermined bias potential increases the beam current of the ion beam.
[0025] To achieve the above and related objects, the present disclosure includes the configurations that are fully described below and particularly recited in the claims. The following description and the accompanying drawings disclose exemplary embodiments of the invention in detail. However, these embodiments merely illustrate some of the various ways of using the principles of the invention. Other objects, advantages, and novel features of the invention will become apparent from the detailed description of the invention when taken in conjunction with the drawings.
[0026] [Brief Description of the Drawings] FIG. 1 is a block diagram of an exemplary vacuum system that utilizes an ion source according to various aspects of the present disclosure.
[0027] FIG. 2A is a block diagram in a top view of an exemplary arc chamber according to various aspects of the present disclosure.
[0028] FIG. 2B is a block diagram in a side view of an exemplary arc chamber according to various aspects of the present disclosure.
[0029] FIG. 3 is a graph showing various beam currents achieved using various bias voltage differences between bias electrodes according to various aspects of the present disclosure.
[0030] FIG. 4 shows a perspective view of an ion source according to various aspects of the present disclosure.
[0031] FIG. 5 shows a partial perspective cross-sectional view of the ion source of FIG. 4.
[0032] FIG. 6 shows a perspective cross-sectional side view of an arc chamber according to various aspects of the present disclosure.
[0033] FIG. 7 shows a perspective cross-sectional top view of an exemplary arc chamber according to various aspects of the present disclosure.
[0034] FIG. 8 shows a cross-sectional plan view of an exemplary arc chamber according to various aspects of the present disclosure.
[0035] FIG. 9 shows a cross-sectional elevation view of an exemplary arc chamber according to various aspects of the present disclosure.
[0036] [Detailed Description] This disclosure generally pertains to ion implantation systems and associated ion sources. More specifically, this disclosure pertains to systems and apparatus for increasing ion beam current and ion source lifetime. The invention is described with reference to the drawings. Throughout, similar reference numerals may be used to refer to similar elements. It should be understood that these descriptions of embodiments are merely illustrative and should not be construed as restrictive. Various specific details are included in the following description for illustrative purposes to provide a full understanding of the invention. Those skilled in the art will see that the invention may be carried out without these specific details. Furthermore, the scope of the invention is not intended to be limited by the embodiments or examples described below with reference to the accompanying drawings, but only by the appended claims and their equivalents.
[0037] It should also be noted that the drawings are provided to illustrate multiple aspects of the embodiments of this disclosure and should be considered as schematic only. In particular, the elements shown in the drawings are not necessarily on the same scale as one another, and the arrangement of the various elements in the drawings is chosen to provide a clear understanding of each embodiment and should not necessarily be interpreted as representing the actual relative positions of the various components in the embodiment of the present invention. Furthermore, the configurations of the various embodiments and examples described herein are combinable with respect to one another unless otherwise specified.
[0038] In the following description, any direct connection or coupling between functional blocks, devices, components, circuit elements, or other physical or functional units shown in the drawings or described herein may also be embodied by indirect connections or couplings. Furthermore, functional blocks or units shown in the drawings may be embodied as individual configurations or components in some embodiments, or alternatively, as common configurations or components in other embodiments, in whole or in part.
[0039] To help understand the present disclosure, Figure 1 shows an exemplary vacuum system 100. This exemplary vacuum system can embody various apparatuses, systems, and methods of the present disclosure. In this example, the vacuum system 100 comprises an ion implantation system 101. However, various other types of vacuum systems, such as plasma processing systems or other semiconductor processing systems, are also considered. The ion implantation system 101 comprises, for example, a terminal 102, a beamline assembly 104, and an end station 106.
[0040] Generally, the ion source 108 in terminal 102 is connected to a power supply 110. In this case, the source gas 112 (also called dopant gas) supplied to the ion source is ionized into multiple ions, forming an ion beam 114. In this example, the ion beam 114 is guided through a beam steering device 116 to exit the aperture 118 and head towards the end station 106. At the end station 106, the ion beam 114 collides with a workpiece 120 (e.g., semiconductors such as silicon wafers, display panels). The workpiece is selectively clamped or mounted to a chuck 122 (e.g., an electrostatic chuck or ESC). When the implanted ions are embedded in the lattice of the workpiece 120, they alter the physical and / or chemical properties of the workpiece. For this reason, ion implantation is used not only in the manufacture of semiconductor devices and metal finishing, but also in various applications in materials science research.
[0041] The ion beam 114 in this disclosure may take any form, such as a pencil beam or spot beam, a ribbon beam, a scanning beam, or any other form in which ions are guided to the end station 106. All such forms are considered to be within the scope of this disclosure.
[0042] In one exemplary embodiment, the end station 106 includes a process chamber 124 (e.g., a vacuum chamber 126). The process environment 128 is associated with the process chamber. The process environment 128 within the process chamber 124 includes, for example, a vacuum. The vacuum is generated by a vacuum source 130 (e.g., a vacuum pump) connected to the process chamber and configured to substantially (sufficiently) evacuate the process chamber. Furthermore, a controller 132 is provided for overall control of the vacuum system 100.
[0043] This disclosure provides an apparatus configured to increase the beam current and availability of ion source 108 while reducing the downtime of the ion source in the ion implantation system 101 described above. The apparatus of this disclosure may be embodied in various semiconductor processing equipment such as CVD, PVD, MOCVD, etching equipment, and various other semiconductor processing equipment, and it should be understood that all such embodiments are considered to be within the scope of this disclosure. The apparatus of this disclosure further advantageously increases the length of use of ion source 108 between preventive maintenance cycles. Thus, the apparatus increases the overall productivity and lifespan of the system vacuum 100.
[0044] The ion source 108 plays a significant role, for example, in the ion implantation system 101. Therefore, the performance of the ion source 108 can play a significant role in metrics related to the ion implantation system 101, such as throughput, uptime, glitch rate, and desired implantation parameters such as the energy state of the desired ion species.
[0045] Next, refer to Figures 2A and 2B. These figures present an exemplary hardware configuration and operating principle of the ion source 108 of Figure 1, according to various aspects of the present disclosure. Figure 2A shows, for example, the ion source 200 for forming an ion beam 202. Figure 2B shows a cross section 204 perpendicular to the ion beam (for example, the ion beam is directed inward in Figure 2B). The ion source 200 in this example comprises various IHC components (e.g., cathode 208 and repeller 210) located within the arc chamber 212. The ion beam 202 is drawn out through the extraction aperture 214. Thus, for example, a magnetic field (e.g., indicated as "B" in Figure 2A) can be applied longitudinally to the ion source 200 (e.g., inward and outward in Figure 2A) using the cathode 208 and repeller 210.
[0046] In this example, Figures 2A and 2B further show a pair of bias electrodes identified as the first bias electrode 216A and the second bias electrode 2216B, which are roughly U-shaped when viewed from the end 217 of the arc chamber 212 in Figure 2B. The first bias electrode 216A and the second bias electrode 216B are electrically insulated from the arc chamber 212 by, for example, one or more electrical insulators 218A, 218B. As an example, one or more electrical insulators 218A, 218B are provided outside the arc chamber 212, as described below. In this case, coating of the one or more insulators by the ion source material is largely reduced. Thus, electrical short circuits of the bias electrodes 216A, 216B to the arc chamber can be largely prevented.
[0047] As shown in Figure 2A, for example, an electrode power supply 220 is provided. This electrode power supply is configured to positively bias the first bias electrode 216A and the second bias electrode 216B with respect to the arc chamber 212. For example, the electrode power supply 220 includes a first power supply 222A and a second power supply 222B. The first and second power supplies are electrically connected to the first bias electrode 216A and the second bias electrode 216B, respectively, and are configured to supply a first positive voltage 224A to the first bias electrode and a second positive voltage 224B to the second bias electrode, respectively. According to this disclosure, the first positive voltage 224A differs from the second positive voltage 224B by a predetermined bias difference (e.g., 10V).
[0048] As an alternative, the electrode power supply 220 may include a single bias power supply electrically connected to each of the first bias electrode 216A and the second bias electrode 216B. In this case, a resistor (not shown) having a fixed or variable resistance is connected between the first bias electrode and the second bias electrode. Therefore, if the resistor is a fixed resistor, the voltage drop across the resistor can supply a fixed value for a given bias difference. Alternatively, if the resistor is a variable resistor, the given bias difference can be selectively changed.
[0049] According to this disclosure, the first bias electrode 216A and the second bias electrode 216B are configured to be in close proximity to each other in a region 228 located approximately opposite the extraction aperture 214. This disclosure understands that, for example, the first bias electrode 216A and the second bias electrode 216B being in close proximity to each other by a first distance 230 (e.g., a gap of about a few millimeters) in the region 228 opposite the extraction aperture 214 can advantageously provide an increased ion beam current compared to conventional ion sources.
[0050] In the draw-out region 232 adjacent to the draw-out opening 214, for example, the first bias electrode 216A and the second bias electrode 216B may be separated by a second distance 234. This second distance is greater than the first distance 230. The second distance 234 is, for example, about twice the draw-out opening width 236 of the draw-out opening 214. In one non-limiting example, if the draw-out opening width 236 is about 5 mm, the second distance 234 is about 10 mm.
[0051] In another embodiment, the disclosure considers independently (e.g., individually) biasing each of the first bias electrode 216A and the second bias electrode 216B to their respective positive first and second bias voltages, which are higher than the ground potential. This allows the beam current of the ion beam 202 to increase more favorably than a conventional ion source having at least one bias electrode that is grounded, or a plurality of bias electrodes having the same applied bias voltage.
[0052] Figure 3 shows an example of triple-charged arsenic (i.e., As) according to various embodiments of the present invention. +++ Or As 3+)Graph 300 illustrates the ion beam current realized in an ion beam.Graph 300 shows, for example, the ion beam current 301 of the ion beam drawn from the ion source for a range of bias electrode voltages 302.A baseline 303 is provided for comparison using a conventional IHC ion source.In this example, a constant ion beam current 301 may be observed when both electrodes are electrically grounded.In contrast, in Figure 3, the ion beam currents 301 associated with each of the multiple first bias electrode voltages 304, 306, 308, 310, 312, 314, 316, 318 applied to the first bias electrode 216A in Figures 2A-2B may be observed when the second bias electrode 216B is energized by various second bias electrode voltages 302 ranging from 0V to +60V.
[0053] In Figure 3, for example, the first bias electrode voltage 316 represents the +50V potential bias applied to the first bias electrode 216A over the above range of the second bias electrode voltage 302. In this example, a maximum value or peak 322 (e.g., approximately 1790 μA) is observed in the ion beam current 301 when the second bias electrode potential is biased to approximately +40V. In this case, the potential difference between the first bias electrode and the second bias electrode is approximately 10V.
[0054] In another example, the first bias electrode voltage 318 in Figure 3 causes the ion beam current 301 to reach a maximum value or peak 324 (e.g., approximately 1820 μA) when the first bias electrode 216A in Figures 2A-2B is positively biased at +60 V, while the second bias electrode 216B is positively biased at +50 V. In this example as well, the potential difference between the first and second bias electrodes is approximately 10 V. Similarly, a similar 10 V potential difference that produces the maximum ion beam current is observed in various other voltage schemes applied to the first bias electrode 216A and the second bias electrode 216B. These are supported, for example, by the so-called E×B drift effect, which moves ions from the plasma to the extraction aperture 214.
[0055] As such, FIG. 3 shows an example of the experimental results of the present disclosure where the maximum beam current can be achieved when the first bias electrode 216A and the second bias electrode 216B in FIGS. 2A-2B have a potential difference of about 10V. In other experiments of the present disclosure, various other ion source parameters (e.g., source magnet power, gas flow rate, etc.) were adjusted. For example, with a first bias electrode voltage of +55V and a second bias electrode voltage of +45V, As +++ It was shown that the maximum ion beam current optimal for the ion beam can be produced. In this case, it was also shown that when the voltage was increased beyond these values, a general decrease in return occurred.
[0056] In the present disclosure, while using other ion species (e.g., As 2+ As 4+ B 2+ B 3+ P 2+ P 3+ etc.), providing a differential bias between the first bias electrode 216A and the second bias electrode 216B is further considered to advantageously provide an increase in the ion beam current of 1.5 to 3.5 times compared to the ion beam current in a conventional device without bias electrodes, a conventional device with equally biased bias electrodes, or a conventional device with one grounded bias electrode. As such, the present disclosure takes into account a predetermined differential bias between the first bias electrode 216A and the second bias electrode 216B. In this case, the fact that both the first electrode and the second electrode are positively biased is a novel discovery that was not foreseen.
[0057] As such, the present disclosure provides a pair of bias electrodes 216A, 216B configured to be individually positively biased by a predetermined bias difference. Thereby, triply charged arsenic (As 3+An increase in ion beam current can be achieved by using multiple charged ions such as ). In contrast to the electrical grounding of the first bias electrode 216A (e.g., grounded to the arc chamber 212) and the positive bias of the second bias electrode 216B, this disclosure supplies an electrical bias to both the first and second bias electrodes. As a result, a predetermined bias difference is supplied between the first and second bias electrodes, and both the first and second electrodes are positively biased to electrical ground. In one preferred embodiment, a predetermined bias difference of about 10V is supplied between the first bias electrode 216A and the second bias electrode 216B, while a positive arc voltage (e.g., 100V) is supplied to the cathode 208. In this case, a larger ion beam current than conventionally observed is obtained.
[0058] Figure 4 shows an exemplary ion source 400. Various further embodiments of the present disclosure will be understood from Figure 4. The ion source 400 includes, for example, an IHC ion source 402. In this example, a cathode 404 (e.g., an indirectly heated cathode 406) is located in the chamber space 408 of an arc chamber 410 to generate ions of a desired species. The cathode 404 is located, for example, in close proximity to the first end 412 of the arc chamber 410. A repeller 414 is located in the chamber space 408 in close proximity to the second end 416 of the arc chamber 410. In this example, the second end is located approximately opposite the first end 412.
[0059] Figure 5 illustrates the blow-up (expansion) portion 418 of the arc chamber 410 in the IHC ion source 400 of Figure 4. Various embodiments are shown in more detail in Figure 5. As shown in Figure 5, for example, an aperture plate 420 is operably connected to the arc chamber 410 and generally surrounds the chamber space 408. In this example, the aperture plate 420 includes a drawout opening 422 located between the first end 412 and the second end 416 of the arc chamber 410. In this example, the drawout opening 422 of the aperture plate 420 is configured to produce an elongated beam (not shown). However, other shapes of the drawout opening are also considered to be within the scope of this disclosure. Furthermore, various suppression electrodes and ground electrodes (not shown) may be provided to draw the ion beam from the arc chamber 410 while the arc chamber is maintained at a positive terminal potential.
[0060] As further shown in Figures 6 and 7, within the chamber space 408, the first bias electrode 424 is positioned on the first side 426 of the drawout opening 422. For example, as shown in Figure 7, the first bias electrode 424 is substantially U-shaped when viewed from the first end 412 of the arc chamber 410 in Figure 6. As shown in Figure 7, for example, within the chamber space 408, the second bias electrode 428 is further positioned on the second side 430 of the drawout opening 422. The second bias electrode is also substantially U-shaped when viewed from the first end 412 of the arc chamber 410 in Figure 6. While the U-shaped first bias electrode 424 and second bias electrode 428 are exemplified in this disclosure, various other arched, angled, or other U-shaped configurations are considered to be within the scope of this disclosure.
[0061] As shown in Figure 8, for example, the first bias electrode 424 and the second bias electrode 428 are separated by a first distance 432 in the first region 434 proximal to the extraction opening 422. Furthermore, for example, the first bias electrode 424 and the second bias electrode 428 are separated by a second distance 436 in the second region 438 distal to the extraction opening 422. The electrode power supply 220 in Figure 2A may be electrically connected to the first bias electrode 424 and the second bias electrode 428 in Figure 8. This electrode power supply is configured to supply a first positive voltage 224A to the first bias electrode and a second positive voltage 224B to the second bias electrode. As described above, the second positive voltage differs from the first positive voltage by a predetermined bias amount.
[0062] As shown in Figure 9, the first bias electrode 424 and the second bias electrode 428 extend for a predetermined length 440 between their respective positions, for example, adjacent to the first end 412 and the second end 416 of the arc chamber 410. For example, the predetermined length 440 is longer than the length 441 of the drawout opening 422.
[0063] In another example, the first distance 432 shown in Figure 8 is greater than the second distance 436 (for example, about twice the second distance). For example, the first distance 432 is greater than the width 442 of the drawout opening. As an example, each of the first bias electrode 424 and the second bias electrode 428 has a bevel 444 that defines the first distance 432. Each bevel is associated with a line (not shown) extending from the respective adjacent edge 446 of the drawout opening 422 toward the respective first and second electrodes.
[0064] As shown in Figure 9, this disclosure considers that the arc chamber 410 further comprises a gas hole 446. The gas hole is defined in the wall 448 of the arc chamber. The gas hole is located between the first end 412 and the second end 416 of the arc chamber 410. For example, the gas hole 446 is adjacent to a second region 438. The gas hole may be fluidly connected to a gas source (not shown) for supplying source gas to the arc chamber 410.
[0065] In another example, the first bias electrode 424 and the second bias electrode 428 shown in Figure 8 each comprise plates 450A and 450B, respectively. The plates 450A and 450B are supported by one or more rods 452A and 452B that extend through the wall 454 of the arc chamber 410. For example, one or more rods 452A and 452B are clamped to their respective electrode clamps 456A and 456B. Each clamp, one or more rods, and the plates 450A and 450B are electrically insulated from the arc chamber 410.
[0066] While the present invention is illustrated and described in relation to specific embodiments, it should be noted that the above-described embodiments serve only as examples for embodying some embodiments of the present invention, and the scope of the present invention is not limited to these embodiments. In particular, with respect to the various functions performed by the above-described components (assemblies, devices, circuits, systems, etc.), the terms used to describe such components (including references to “means”) are intended, unless otherwise specified, to correspond to any component that performs its function (i.e., is functionally equivalent) to the described component, even if it is not structurally equivalent to the disclosed configuration, as long as it performs that function in the exemplary embodiments of the present invention illustrated herein. Furthermore, while a particular configuration of the present invention is disclosed for only one of several embodiments, that configuration may be combined with one or more configurations in other embodiments which are desirable and advantageous for any given or particular use. Accordingly, the present invention should not be limited to the above-described embodiments, but should be limited only by the appended claims and their equivalents. [Brief explanation of the drawing]
[0067] [Figure 1] This is a block diagram of an exemplary vacuum system utilizing an ion source according to multiple embodiments of the present disclosure. [Figure 2A] This is a top view block diagram of an exemplary arc chamber relating to multiple embodiments of the present disclosure. [Figure 2B] This is a side view block diagram of an exemplary arc chamber according to several embodiments of the present disclosure. [Figure 3] This graph shows various beam currents realized using various bias voltage differences between bias electrodes according to multiple embodiments of this disclosure. [Figure 4] Perspective views of ion sources relating to various aspects of this disclosure are shown. [Figure 5] Figure 4 shows a partial perspective cross-sectional view of the ion source. [Figure 6]The following are perspective cross-sectional side views of arc chambers according to various embodiments of this disclosure. [Figure 7] An exemplary top view of an arc chamber in a perspective cross-section relating to various aspects of this disclosure is shown. [Figure 8] The following are cross-sectional plan views of exemplary arc chambers relating to various aspects of this disclosure. [Figure 9] The following are cross-sectional elevation views of exemplary arc chambers relating to various aspects of this disclosure.
Claims
1. It is an ion source, Arc chamber and Opening plate and Cathode and, Repera and, First bias electrode and The second bias electrode, It is equipped with an electrode power supply, The arc chamber has a first end and a second end located on the opposite side from the first end. The opening plate, by being operably connected to the arc chamber, generally encloses the chamber space. The opening plate includes a drawout opening located between the first end and the second end of the arc chamber, The cathode is located inside the chamber space, close to the first end of the arc chamber. The repeller is positioned inside the chamber space, close to the second end of the arc chamber. The first bias electrode is located inside the chamber space on the first side of the extraction opening. When viewed from the first end, the first bias electrode is substantially U-shaped, The second bias electrode is located inside the chamber space, on the second side of the extraction opening. When viewed from the first end, the second bias electrode is substantially U-shaped, In the first region proximal to the extraction opening, the first bias electrode and the second bias electrode are separated by a first distance. In a second region distal to the extraction opening, the first bias electrode and the second bias electrode are separated by a second distance. The electrode power supply is electrically connected to the first bias electrode and the second bias electrode. The electrode power supply provides a first positive voltage to the first bias electrode and a second positive voltage to the second bias electrode. The second positive voltage differs from the first positive voltage by a predetermined bias difference. The first distance is greater than the second distance for the ion source.
2. The ion source according to claim 1, wherein the first bias electrode and the second bias electrode extend by a predetermined length between their respective positions adjacent to the first end and second end of the arc chamber.
3. The ion source according to claim 1, wherein the first bias electrode and the second bias electrode have an arch shape when viewed from the first end of the arc chamber.
4. The ion source according to claim 1, wherein the first distance is twice the second distance.
5. The ion source according to claim 1, wherein the first distance is greater than the width of the extraction opening.
6. Each of the first bias electrode and the second bias electrode is provided with a bevel that determines the first distance, The ion source according to claim 1, wherein each bevel is associated with a line extending from the respective adjacent edge of the extraction opening toward the respective first bias electrode and the second bias electrode.
7. The arc chamber further comprises a gas hole defined in the wall of the arc chamber, The gas hole is located between the first end and the second end of the arc chamber, which is adjacent to the second region. The ion source according to claim 1, wherein the gas hole is fluidly connected to a gas source.
8. The ion source according to claim 1, wherein the predetermined bias difference is on the order of 10 volts.
9. The electrode power supply includes a first power supply and a second power supply. The first power supply supplies the first positive voltage to the first bias electrode, The ion source according to claim 1, wherein the second power supply supplies the second positive voltage to the second bias electrode.
10. It also has a resistive element, The resistive element is electrically connected between the electrode power supply and the second bias electrode. The resistance of the resistive element determines the predetermined bias difference, as described in claim 1.
11. The ion source according to claim 10, wherein the resistive element includes a variable resistor having selectively variable resistance.
12. Each of the first bias electrode and the second bias electrode comprises a plate supported by one or more rods, One or more of the rods extend through the wall of the arc chamber and are clamped to their respective electrode clamps. The ion source according to claim 1, wherein each of the clamps, one or more of the rods, and the plate are electrically insulated from the arc chamber.
13. The cathode includes an indirectly heated cathode comprising a heater filament and a cap. The ion source according to claim 1, wherein the heater filament is electrically connected to a heater power supply that selectively energizes and heats the cap.
14. It is an ion source, Arc chamber and Indirect heating cathode and First bias electrode and The second bias electrode, It is equipped with a resistive element, The arc chamber has a first arc chamber wall that extends from the first end of the arc chamber to the second end of the arc chamber, The first arc chamber wall has a drawout opening defined inside the first arc chamber wall, The aforementioned draw-out opening is located between the first end and the second end of the arc chamber, The indirect heating cathode is positioned close to the first end of the arc chamber. The indirect heating cathode comprises a heater filament and a cap, The heater filament receives power to heat the cap, The first bias electrode is positioned on the first side of the arc chamber, between the first end and the second end. When viewed from the first end, the first bias electrode is substantially U-shaped, The second bias electrode is positioned on the second side of the arc chamber, between the first end and the second end. When viewed from the first end, the second bias electrode is substantially U-shaped, The resistive element is associated with one or more of the first bias electrode and the second bias electrode, The resistance of the resistive element determines a predetermined bias difference between the first bias electrode and the second bias electrode, which is an ion source.
15. In the first region proximal to the extraction opening, the first bias electrode and the second bias electrode are separated by a first distance. In a second region distal to the extraction opening, the first bias electrode and the second bias electrode are separated by a second distance. The ion source according to claim 14, wherein the first distance is greater than the second distance.
16. The system further includes an electrode power supply electrically connected to the first bias electrode and the second bias electrode, The electrode power supply provides a first positive voltage to the first bias electrode and a second positive voltage to the second bias electrode. The ion source according to claim 14, wherein the second positive voltage differs from the first positive voltage by the predetermined bias difference.
17. The electrode power supply includes a first power supply and a second power supply. The first power supply supplies the first positive voltage to the first bias electrode, The second power supply supplies the second positive voltage to the second bias electrode. The ion source according to claim 16, wherein the predetermined bias difference is on the order of 10 volts.
18. The ion source according to claim 16, wherein the resistive element is electrically connected between the electrode power supply and the second bias electrode.
19. A method for increasing the beam current in an indirectly heated cathode (IHC) ion source according to any one of claims 1 to 18, The method includes the step of electrically biasing an indirect heating cathode located inside the arc chamber. The indirect heating cathode is biased toward the first and second arc chamber walls, which are opposite each other. The first arc chamber wall is provided with a drawout opening located between the first and second ends of the arc chamber. The method includes the step of electrically biasing the first bias electrode with respect to the second bias electrode by a predetermined bias difference, The first bias electrode and the second bias electrode are positioned between the first end and the second end of the arc chamber. The first bias electrode and the second bias electrode are separated by a first gap adjacent to the first arc chamber wall and a second gap adjacent to the second arc chamber wall. The method includes the step of drawing out an ion beam through the extraction opening, A method for increasing the beam current of the ion beam by the predetermined bias difference.