Active heating target for generating an ion beam

Abstract

An arc chamber for an ion source defines a chamber volume, and a target material is disposed within the chamber volume. The target material includes a dopant species and may be included in the target member. An indirect heating cathode is disposed within the chamber volume and ionizes the source gas within the chamber volume thereby defining a plasma having plasma thermal radiation. The target heater selectively heats the target material independently of plasma thermal emission associated with the plasma. The target heater may be a resistive heating element, an induction heating element, a halogen heating element, or a laser configured to selectively heat at least a portion of the target member. The target member may be composed of a solid dopant material, or may include a liquid dopant material.

Description

[0001] Cross-reference to related applications This application claims the benefit of U.S. Provisional Application No. 63 / 588,110, filed October 5, 2023, entitled “Actively Heated Target for Generating Ion Beams,” the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present invention relates generally to ion implantation systems, and more specifically to targets for actively heating ion sources, thereby enhancing the etching and sputtering of target materials and providing improved productivity of the ion source. Background Technology

[0003] In semiconductor device manufacturing, ion implantation is used to dope semiconductors with impurities. Ion implantation systems are typically used to dope workpieces (such as semiconductor wafers) with ions from an ion beam to produce n-type or p-type material doping, or to form passivation layers during integrated circuit manufacturing. This beam treatment is typically used to selectively implant impurities containing specified dopant materials into wafers at predetermined energy levels and controlled concentrations to produce semiconductor materials during integrated circuit manufacturing. When used to dope semiconductor wafers, ion implantation systems implant selected ion species into the workpiece to produce the desired intrinsic material. For example, implanting ions from source materials such as antimony, arsenic, or phosphorus results in “n-type” intrinsic material wafers, while “p-type” intrinsic material wafers are typically generated from ions from source materials such as boron, gallium, or indium.

[0004] A typical ion implanter includes an ion source, an ion extraction unit, a mass analysis unit, a beam delivery unit, and a wafer processing unit. The ion source generates ions of the desired atomic or molecular dopant species. These ions are extracted from the ion source by an extraction system (typically a set of electrodes) that excites and directs the ion stream from the source, forming an ion beam. In the mass analysis unit, the desired ions are separated from the ion beam, typically by mass dispersion or separation of the extracted ion beam using magnetic dipoles. The beam delivery unit is typically a vacuum system containing a series of focusing devices that transports the ion beam to the wafer processing unit while maintaining the desired characteristics of the ion beam. Finally, the semiconductor wafer is moved into or out of the wafer processing unit via a wafer handling system (which may include one or more robotic arms) to place the wafer to be processed in front of the ion beam and remove the processed wafer from the ion implanter. Summary of the Invention

[0005] Therefore, this disclosure provides a system and apparatus for increasing the productivity of an ion source in an ion implantation system. A simplified overview of this disclosure is thus provided to offer a basic understanding of some aspects of the invention. This overview is not a broad summary of the invention. It is not intended to identify key or essential elements of the invention, nor is it intended to depict the scope of the invention. Its purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that follows.

[0006] According to one exemplary aspect of this disclosure, an arc chamber for an ion source is provided, wherein the arc chamber defines a chamber volume. For example, a target material is disposed within the chamber volume, wherein the target material comprises dopant species. In one example, an indirect heating cathode is positioned within the chamber volume, wherein the indirect heating cathode is configured to ionize a source gas within the chamber volume, thereby defining a plasma having associated thermal plasma emission. Further, a target heater is provided, and the target heater is configured to selectively heat the target material within the chamber volume independently of the thermal plasma emission associated with the plasma. For example, the target heater may include one or more of a resistance heating element, an induction heating element, a radiation heating element (such as a quartz halogen heating element), or a laser.

[0007] In one example, a reflector is positioned within a cavity volume, wherein the reflector includes a reflector axis and a target member. For example, the target member comprises a target material, and a target heater is configured to selectively heat at least a portion of the reflector axis, thereby selectively heating the target member. For example, the reflector axis may include a hollow portion and a solid portion, wherein the hollow portion defines a cavity within the reflector axis. Thus, the target heater may, for example, be configured to selectively heat the solid portion by the transfer of thermal energy through the cavity.

[0008] For example, the target heater may be positioned within the cavity and include either a resistance heating element or an induction heating element. Alternatively, the target heater may include, for example, a quartz halogen heating element or a laser, wherein the target heater can be guided through the cavity toward the solid portion. For example, the target heater may be positioned outside the arc chamber.

[0009] For example, the target component may include a hollow cylinder that generally surrounds at least a portion of the reflective polar axis. For example, the target component may be separated from the reflective polar axis by a gap, or the target component may be in thermal communication with at least a portion of the reflective polar axis.

[0010] In another example, the target component includes a reservoir operatively coupled to the reflective polar axis, wherein the reservoir is configured to contain liquid target material therein.

[0011] In yet another example, a power source is provided and configured to electrically bias, levitate, or ground one or more of the target member or reflector relative to one or more of the arc chamber, the indirect heating cathode, or the target heater. In one example, the target member is electrically coupled to the power source. According to another example, the target member is operatively coupled to the arc chamber.

[0012] For example, the target component may include a target cylinder that generally surrounds an indirectly heated cathode. For example, the target heater may include an indirectly heated cathode. In another example, the target component may include a reservoir positioned within an arc chamber and configured to contain liquid target material therein. Alternatively, the target component may include or contain solid target material. For example, the arc chamber may include one or more chamber walls, and one or more of the target component or target heater may be operatively coupled to one or more chamber walls.

[0013] According to another exemplary aspect, an arc chamber for an ion source is provided, wherein a target member is disposed within the arc chamber, and wherein the target member is configured to comprise a dopant material. An indirect heating cathode is positioned within the arc chamber, wherein the indirect heating cathode is configured to define a plasma within the arc chamber, and wherein the plasma has associated thermal emission. For example, a target heater is also configured to selectively heat the target member independently of the thermal emission associated with the plasma. The target heater may include one or more of a resistance heating element, an induction heating element, a quartz halogen heating element, or a laser.

[0014] The arc chamber of this example may include a reflector located therein, with a target member proximate to the reflector, and a target heater configured to selectively heat at least a portion of the reflector, thereby selectively heating the target member. The reflector may include a reflector shaft having a hollow portion and a solid portion, wherein the hollow portion defines a cavity within the reflector shaft, and the target heater is configured to selectively heat the solid portion by means of heat energy transfer through the cavity.

[0015] The target may be located within the cavity and include either a resistance heating element or an induction heating element. Alternatively, the target heater may include either a quartz halogen heating element or a laser, wherein the target heater is guided through the cavity toward the solid portion. For example, the target component may include a hollow cylinder that substantially surrounds at least a portion of the reflector. Furthermore, the target component may be separated from the reflector by a gap.

[0016] For example, the target component may include a reservoir operatively coupled to a reflector or arc chamber, wherein the reservoir is configured to contain liquid dopant material therein. The target component may alternatively or additionally include a target barrel substantially surrounding an indirect heating cathode, thereby allowing the target heater to additionally include an indirect heating cathode. The arc chamber may also include one or more walls, wherein one or more of the target component and the target heater are operatively coupled to or associated with one or more walls.

[0017] According to another exemplary aspect of this disclosure, a method for controlling an ion source is provided. In one example, the method includes forming a plasma within an arc chamber, thereby defining plasma thermal emission. Further, a target component containing dopant material disposed within the arc chamber is selectively heated independently of plasma thermal emission. For example, by selectively heating the target component independently of plasma thermal emission, a faster transition between dopant species at different temperatures can be advantageously achieved. For example, selectively heating the target component may include heating the target component to a predetermined operating temperature before forming a plasma within the arc chamber. Alternatively or additionally, selectively heating the target component may include heating the target component to the predetermined operating temperature while forming a plasma within the arc chamber. For example, the predetermined operating temperature may be greater than a predetermined plasma temperature associated with heating the target component solely by plasma thermal emission.

[0018] To achieve the foregoing and related objectives, this disclosure includes the features fully described below and particularly pointed out in the claims. The following description and drawings illustrate certain illustrative embodiments of the invention in detail. However, these embodiments indicate several of a variety of ways in which the principles of the invention can be employed. Other objects, advantages, and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings. Attached Figure Description

[0019] Figure 1 This is a block diagram of an exemplary vacuum system utilizing an ion source according to several aspects of this disclosure.

[0020] Figure 2 A perspective view of an ion source according to various exemplary aspects of this disclosure is shown.

[0021] Figure 3 Various exemplary aspects according to this disclosure are shown. Figure 2 A partial cross-sectional view of the arc chamber of the ion source.

[0022] Figure 4 Partial cross-sectional views of reflector assemblies and target components according to various exemplary aspects of this disclosure are shown.

[0023] Figure 5Partial cross-sectional views of reflector assemblies and target components according to several examples of this disclosure are shown.

[0024] Figure 6 A partial cross-sectional view of another reflector assembly according to several examples of the present disclosure is shown, the other reflector assembly having a solid member extending through the chamber wall.

[0025] Figure 7 A partial cross-sectional view of another reflector assembly according to several examples of the present disclosure is shown, the other reflector assembly having a solid member heated by an induction coil.

[0026] Figure 8 A partial cross-sectional view of another reflector assembly reservoir according to several examples of this disclosure is shown.

[0027] Figure 9 A cross-sectional view of an indirect heating cathode according to several examples of the present disclosure is shown, the indirect heating cathode having a target member including a cathode shield.

[0028] Figure 10 This is a flowchart of a method for heating a target material according to several examples of this disclosure. Detailed Implementation

[0029] This disclosure generally relates to an ion implantation system and an associated ion source. More specifically, this disclosure relates to an improved arc chamber for said ion source and associated components, thereby improving the productivity of the ion source.

[0030] Therefore, the invention will now be described with reference to the accompanying drawings, wherein like reference numerals may be used throughout to refer to like elements. It should be understood that these descriptions are merely illustrative and should not be construed as limiting. In the following description, numerous specific details are set forth for purposes of explanation in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without these specific details. Furthermore, the scope of the invention is not intended to be limited to the embodiments or examples described below with reference to the accompanying drawings, but is intended to be limited only to the appended claims and their equivalents.

[0031] It should be noted that the accompanying drawings are provided to illustrate some aspects of embodiments of this disclosure, and therefore the drawings are to be considered illustrative only. In particular, the elements shown in the drawings are not necessarily drawn to scale, and the placement of various elements in the drawings is chosen to provide a clear understanding of the respective embodiments and should not be construed as a representation of the actual relative positions of various components in an embodiment according to the invention. Furthermore, features of the various embodiments and examples described herein can be combined with each other unless otherwise specifically stated.

[0032] It should also be understood that, in the following description, any direct connection or coupling between functional blocks, devices, components, elements, or other physical or functional units shown in the figures or described herein may also be achieved through indirect connection or coupling. Furthermore, it should be understood that functional blocks or units shown in the figures may be implemented as separate features in one embodiment, and may also, or alternatively, be implemented wholly or partially in a common feature in another embodiment.

[0033] Ion sources (often referred to as arc ion sources) generate an ion beam for an implanter and may include a cathode for heating a filament to generate and shape ions into a suitable ion beam for wafer processing. For example, U.S. Patent No. 5,497,006 to Sferlazzo et al. discloses an ion source having a cathode supported by a pedestal and positioned relative to a gas confinement chamber for ejecting ionized electrons into the gas confinement chamber. The cathode of Sferlazzo et al. is a tubular conductor with an end cap that extends partially into the gas confinement chamber. A filament supported within the tubular body emits electrons that heat the end cap through electron bombardment, thereby causing thermionic electrons to emit ionized electrons into the gas confinement chamber to form a plasma.

[0034] The reflector and cathode are positioned relative to each other, and the target material can be placed near the reflector. The ion source gas (such as fluorine or other volatile species) can enhance the chemical etching of the target material based solely on the heat provided by the plasma.

[0035] Gas supply is the preferred method for supplying material to an ion source to generate ions for implantation. However, in some cases, a gaseous source of the desired atoms or molecules is not readily available. In such cases, a solid target containing a target material (e.g., Al₂O₃, AlN, GaN, or GaAs for Al and Ga ions) is provided, which can withstand the temperatures within the ion source. Alternatively, a container holding a material that is liquid at high temperatures (e.g., pure Al) can be fixed or inserted into the arc chamber.

[0036] Corrosive chemicals (such as halogens like fluorine, chlorine, bromine, or iodine) or halogen-based molecules (such as Cl2, CCl4, BCl3, Br2, HCl, HBr, HI, CHCl3, CBr4, CHBr3, CH) x I y F2, BF3, NF3, PF3, XeF2 or SF6) are used to enhance the removal of materials from the target and their delivery into the plasma.

[0037] However, the rate of this chemical etching is highly temperature-dependent, which can result in waiting times of up to 30 minutes from cold start conditions to generate the required beam current for production. Similar conditions can occur when switching from a first dopant species to a second dopant species, where the power required to generate an acceptable beam current for the first dopant species is significantly lower than that required for the second. This waiting time greatly reduces the productivity of the ion implanter.

[0038] In order to gain an understanding of this disclosure, Figure 1 An exemplary vacuum system 100 is shown, which can implement various apparatuses, systems, and methods of this disclosure. The vacuum system 100 in this example includes an ion implantation system 101, but various other types of vacuum systems are also contemplated, such as plasma processing systems or other semiconductor processing systems. For example, the ion implantation system 101 includes a terminal 102, a beamline assembly 104, and a terminal station 106.

[0039] Generally, an ion source 108 in terminal 102 is coupled to a power source 110, whereby a target material 112 (e.g., a dopant material) is ionized into plasma to form an ion beam 114. In this example, the ion beam 114 is guided through a beam deflector 116 and directed toward a guide aperture 118 toward terminal station 106. In terminal station 106, the ion beam 114 bombards a workpiece 120 (e.g., a semiconductor such as a silicon wafer, a display panel, etc.), which is selectively clamped or mounted to a chuck 122 (e.g., an electrostatic chuck or ESC). Once embedded in the lattice of workpiece 120, the implanted ions alter the physical and / or chemical properties of the workpiece. Therefore, ion implantation is used in semiconductor device fabrication and metal finishing, as well as in various applications in materials science research.

[0040] The ion beam 114 of this disclosure may take any form, such as a pencil beam or dot beam, a strip beam, a scanning beam, or any other form that guides ions toward the terminal station 106, and all such forms are considered to fall within the scope of this disclosure.

[0041] According to one exemplary aspect, terminal station 106 includes a processing chamber 124, such as a vacuum chamber 126, wherein a processing environment 128 is associated with the processing chamber. For example, the processing environment 128 within processing chamber 124 includes a vacuum generated by a vacuum source 130 (e.g., a vacuum pump), which is coupled to the processing chamber and configured to substantially evacuate the processing chamber. Furthermore, a controller 132 is provided for overall control of the vacuum system 100.

[0042] This disclosure provides an apparatus configured to increase the productivity of an ion source 108 while reducing downtime of the ion implantation system 101, for example, when changing the dopant type or during system startup. It should be understood that the apparatus of the present invention can be implemented in various semiconductor processing apparatuses, such as CVD, PVD, MOCVD, etching apparatuses, and various other semiconductor processing apparatuses, and all such implementations are contemplated to fall within the scope of this disclosure.

[0043] In one example, the ion source 108 includes an arc chamber 134 (also called an ion source chamber) that generally defines a chamber volume 136, whereby the arc chamber can be constructed from refractory metals (tungsten, molybdenum, tantalum, etc.) and graphite to provide suitable high-temperature performance, such materials are generally accepted by semiconductor chip manufacturers.

[0044] According to this disclosure, for example, target material 112 is disposed in solid or liquid form within chamber volume 136, wherein the target material includes dopant species (e.g., aluminum, gallium). For example, gas supplier 138 is fluidly coupled to chamber volume 136, whereby an etchant gas having an corrosive chemical composition can be used to etch or otherwise enhance the removal of target material 112 to deliver the dopant species into the plasma. Examples of etchant gases from gas supplier 138 may include halogens (such as fluorine, chlorine, bromine, or iodine) or halide-based molecules (such as Cl2, CCl4, BCl3, Br2, HCl, HBr, HI, CHCl3, CBr4, CHBr3, CH...). x I y (F2, BF3, NF3, PF3, XeF2 or SF6).

[0045] However, this disclosure recognizes that the rate of chemical etching is highly temperature-dependent. For example, when starting up a conventional ion implantation system, a long waiting time is typically required from the so-called cold start state to the generation of an acceptable ion beam suitable for production. Similar waiting times are conventionally observed when changing from a first dopant species to a second dopant species. For example, when the first power required to generate an acceptable beam current for the first dopant species is significantly lower than the second power required to generate an acceptable beam current for the second dopant species, the conventional waiting time associated with increasing the temperature within the ion source solely by relying on plasma significantly reduces the productivity of the ion implanter.

[0046] This disclosure advantageously heats the target material independently of plasma heating, thereby significantly reducing the time required for the arc chamber 134 to reach an acceptable temperature, thus improving the operational efficiency and productivity of the ion implantation system. Consequently, the time required for the ion source 108 to reach the desired operating temperature to achieve the expected ion beam is shortened. Furthermore, this disclosure advantageously provides the ability to heat the target material 112 within the chamber volume 136 to higher temperatures than conventionally achieved using plasma alone, thereby increasing the rate of etching reaction with the target material and providing higher beam current.

[0047] According to a non-limiting example, the ion source 108 may include an indirectly heated cathode 140 disposed within a chamber volume 136, wherein the indirectly heated cathode is configured to further ionize the target material 112 within the chamber volume 136 via control of a power supply 110, thereby defining a plasma having associated thermal plasma emission. For example, a reflector 142 may be further disposed substantially opposite to the indirectly heated cathode 140.

[0048] Generally, according to various examples provided below, a target heater 144 is further provided, and the target heater 144 is configured to selectively heat the target material 112 independently of plasma thermal emission associated with the plasma. For example, the target heater 144 may include one or more of a resistance heating element, an induction heating element, a radiation heating element (such as a quartz halogen heating element), and a laser.

[0049] According to various exemplary aspects of this disclosure, in Figure 2 An exemplary ion source 200 is shown, in which various aspects of this disclosure will be discussed in more detail. Figure 2 The ion source 200 includes an arc chamber 202 configured to form an ion beam (not shown). For example, the ion source 200 generates an ion beam by ionizing a source gas introduced into a chamber volume 204 of the arc chamber 202 through a source gas inlet 206. For example, the source gas inlet 206 may be fluidly coupled to… Figure 1 The gas supply 138 is used to introduce source gas and / or etchant gas into the gas supply. Figure 2 The arc chamber 202 has a chamber volume 204. For example, the ionization process and formation of plasma (not shown) within the chamber volume 204 are achieved by an exciter 208, which may take the form of a thermally heated filament, a heated cathode (indirectly heated cathode, IHC) filament, or a radio frequency (RF) antenna. According to this disclosure, the arc chamber 202 of the ion source 200 of this example is associated with the IHC ion source 210, as follows. Figure 3 This is shown in more detail below.

[0050] For example, the IHC ion source 210 includes a filament 212, an indirectly heated cathode 214, and a reflector 216 (e.g., a countercathode). In this example, the reflector 216 and the indirectly heated cathode 214 are positioned relative to each other generally along axis 218 in the arc chamber 202. It should be noted that although the reflector 216 is shown opposite the indirectly heated cathode, it is not shown, and one or more additional reflectors may be further disposed at various other locations within the arc chamber 202, wherein one or more additional reflectors may have a structure similar to the reflector 216 shown. A further aperture 220 is provided. Figure 1 The ion beam 114 is emitted through this aperture. In one example, a source magnet (not shown) may provide approximately a lateral line between the cathode 214 and the reflector 216. Figure 3 The magnetic field (not shown) of axis 218. For example, during operation of the IHC ion source 210, the filament 212 is resistively heated to a sufficiently high temperature to emit electrons, which are then accelerated to bombard the indirectly heated cathode 214, which is maintained at a positive potential relative to the filament.

[0051] For example, the indirect heating cathode 214 is heated to a sufficiently high temperature to thermally emit electrons into the arc chamber 202, which is maintained at a positive potential relative to the cathode to accelerate the electrons. A magnetic field helps confine the electrons along field lines between the indirect heating cathode 214 and the reflector 216 to reduce electron loss to one or more chamber walls 222 of the arc chamber 202. Electron loss is further reduced by the reflector 216, which can be maintained at the potential of the indirect heating cathode 214 to reflect electrons back to the cathode. The excited electrons ionize the source gas, thereby generating plasma (not shown). Ions are thus extracted through the aperture 220 and electrostatically accelerated by electrodes positioned outside the arc chamber 202 to form a high-energy ion beam.

[0052] In operation, the indirectly heated cathode 214 (e.g., a cathode made of tungsten or tantalum) is indirectly heated via filament 212 and used to initiate and sustain the ion source plasma (e.g., thermionic emission). For example, the indirectly heated cathode 214 and the reflector 216 are at a negative potential relative to one or more chamber walls 222 of the arc chamber 202 (e.g., one or more tungsten pads), and both the cathode and the reflector can be sputtered by ionized gas.

[0053] For example, the reflector axis 226 of the reflector 216 may be made of one or more of tungsten, tantalum, molybdenum, or graphite. In this example, the top reflector portion 228 of the reflector axis 226 is exposed to the plasma within the internal volume and is coaxially aligned with the indirectly heated cathode 214 along the axis 218.

[0054] According to a general aspect of this disclosure, a target member 230 is disposed near a reflective polar axis 226, whereby the target member is configured as a dopant-containing material in solid or liquid form. As shown, the target member 230 is in solid form and generally cylindrical, surrounding the reflective polar axis 226. For example, the target member 230 may be composed of a target material 232 configured for chemical etching and sputtering by an ion source plasma. In one example, the target material is a ceramic containing a metal (e.g., aluminum nitride, aluminum oxide, or aluminum carbide). For example, the metal has a melting temperature greater than 400°C. It should be noted that although this example describes a target material 232 as an aluminum-based ceramic, the invention further contemplates any high-temperature ceramic containing a metal other than aluminum. In yet another example, the target material consists of a metal having a melting temperature greater than 400°C.

[0055] In one example, the target member 230 is operatively coupled to one or more chamber walls 222, for example, mechanically and / or electrically. For instance, the target member 230 may be mechanically and / or electrically coupled to one or more pads 224 associated with one or more chamber walls 222, for example, operatively coupled to a bottom pad 225, wherein the bottom pad is at a return potential or ground potential. The target member 230 in this example is also configured to provide a gap 234 between the target member 230 and the reflective pole axis 226. For example, the gap 234 radially surrounds the reflective pole axis 226 and may be approximately 0.25 mm or greater.

[0056] For example, the target component 230 and / or the reflective pole axis 226 may be electrically grounded or positively biased, negatively biased, or electrically levitated relative to the arc chamber 202. In this example, the target component 230 and the reflective pole axis 226 are not in physical or electrical contact with each other. However, although Figure 3 Not shown, but the target member 230 and the reflector axis 226 may be in contact with each other or otherwise provide thermal and / or electrical conduction between them. Furthermore, although not shown, in other examples, the target member 230 may be slightly above or slightly below the reflector top surface 236 of the reflector axis 226 by a small margin (e.g., about 1 mm), which may be associated with the gap 234. In one example, the gap 234 may provide significant gas conduction within the gap to further expose the target member 230 to further enhance the chemical etching and sputtering of the target material 232.

[0057] In one example, the target component 230 is made of aluminum-containing ceramic (e.g., AlN and Al2O3), whereby an etchant gas (e.g., a halide gas) is injected into the arc chamber 202 via one or more of the source gas inlets 206. For example, the etchant gas may contain chlorinated or fluorinated gases (e.g., Cl2, Cl3, BF3, SiF4, or PF3), bromide gases, iodide gases, or another halide gas. In an example where the etchant gas includes a fluorinated gas, the fluorinated gas is decomposed in the plasma during operation of the arc chamber 202 to produce fluorine, thereby etching aluminum from the target component 230. Therefore, the fluorinated gas (e.g., a dopant gas or a mixture of an inert gas and fluorine) is further directed to the gap 234 between the reflector axis 226 and the target component 230. For example, the target component 230 may be further coupled to a support component 238, whereby the support component may be at a potential of the indirectly heated cathode 214, electrically biased to the indirectly heated cathode, or electrically grounded or insulated from other components.

[0058] According to another exemplary aspect, the target member 230 may be operatively coupled to the target support 240, wherein the target support is configured to support the target member while preventing direct contact between the target member and the reflective polar axis 226. Alternatively, the target member 230 and the reflective polar axis 226 may be in direct contact with each other.

[0059] According to another approach, for example, the reflective polar axis 226 is made of a conductive refractory metal (e.g., tungsten), while the target component 230 is typically non-conductive or insulating (e.g., ceramics such as AlN), which is electrically biased or floating (e.g., charged to a predetermined potential). The negatively biased reflective polar axis 226 generates a negative field, such that a voltage applied to the reflective polar axis can accelerate positively charged ions in its vicinity. Thus, the voltage drop (called the sheath) can accelerate the ions. The greater the bias applied to the reflective polar axis 226, the greater the energy of the acceleration obtained. Therefore, the reflective polar axis 226 improves the ion generation efficiency.

[0060] According to this disclosure, a target heater 242 is further provided, wherein the target heater is configured to selectively heat the target member 230, and thus the target material 232, independently of the plasma thermal emission associated with the aforementioned plasma. The target heater 242 in this example includes a resistance heating element 244 (e.g., a resistance heating filament), which can be electrically coupled to... Figure 1 The power supply 110 is controlled by the controller 132 for its selective activation.

[0061] Refer again Figure 3The target heater 242 is configured, for example, to selectively heat at least a portion 246 of the reflective polar axis 226. Therefore, the reflective polar axis 226 is also configured to selectively heat the target member 230. For example, the reflective polar axis 226 may include a hollow portion 248 and a solid portion 250, as in... Figure 4 In another example, shown in more detail, the hollow portion defines a cavity 252 within the reflective polar axis 226. Therefore, the target heater 242 can, for example, be configured to selectively heat the solid portion 250 by transferring heat energy through the cavity 252. Figure 4 As shown, the reflective polar axis 226 and the target member 230 are in direct contact with each other. However, although not shown, it should be noted that in other examples the reflective polar axis 226 and the target member 230 may be closely adjacent to each other, where no direct contact is formed between them.

[0062] Figure 5 An example is shown in which the target heater 242 includes an emission source 254 (e.g., a quartz halogen heating element and a laser). As shown, the target heater 242 provides energy 256 (e.g., thermal radiation, laser excitation, etc.) to the reflective polar axis 226 (e.g., into the hollow portion 248), thereby selectively heating at least a portion 246 (e.g., the solid portion 250) of the reflective polar axis. In the case where the emission source 254 is a laser, the energy 256 comprises a laser beam 258.

[0063] This disclosure envisions the target heater 242 heating any portion of the target member 230, thus advantageously increasing the etching of the target member at least in part due to the temperature increase of the target member. For example, the reflective pole axis 226 may be solid or hollow, and at least a portion 246 of the reflective pole axis may be positioned at... Figure 3 The arc chamber 202 can be located inside or outside. For example, such as... Figure 6 As shown, the reflective polar axis 226 is generally solid, thereby the solid portion 250 of the reflective polar axis is selectively heated by the target heater 242. In another example, the target heater 242 may include an induction coil 259, for example... Figure 7 As shown. For example, the induction coil 259 is configured to inductively heat the solid portion 250, and the alternating electromagnetic field induces a current in the reflective polar axis 226, thereby providing energy 256 within the reflective polar axis itself.

[0064] For example, Figures 6 to 7 At least a portion 246 of the reflective polar axis 226 shown may be positioned outside one or more chamber walls 222, thereby allowing the target heater 242 to selectively heat the reflective polar axis and thus the target member 230. It should be noted that... Figure 6The target heater 242 shown may include the aforementioned emission source 254, or the target heater may alternatively include any of the following: resistance heating element, induction heating element, quartz halogen heating element, laser, or any heating device configured to selectively heat the target component while keeping it substantially outside the arc chamber.

[0065] According to another example, such as Figure 8 As shown, the target component 230 includes a reservoir 260 operatively coupled to the reflective polar axis 226, wherein the reservoir is configured to contain liquid target material 232 therein. For example, the target heater 242 is further configured to selectively heat at least a portion 246 (e.g., the solid portion 250 of the reflective polar axis 226), thereby selectively heating the target material 232 present in the reservoir 260. For example, the reservoir 260 may be further electrically coupled to... Figure 1 The power supply 110 allows the reservoir to be electrically biased, electrically levitated, or electrically grounded relative to one or more of the arc chamber 134 and the indirect heating cathode 140. For example, the target heater 242 may be further configured to heat the target material 232 to transform the target material from a solid phase to a liquid phase when the target material is present in the reservoir 260.

[0066] In another example, the target component is operatively coupled to any portion of the arc chamber 134, wherein the target component contains target material 112. For example, although noted, one or more of the target component 230 and the target heater 242 are operatively coupled to... Figure 3 One or more chamber walls 222 of the arc chamber 202 shown. For example, the target member 230 may include a plate (not shown) that replaces at least a portion of one or more of the chamber walls 222, whereby the target heater 242 is configured to selectively heat one or more chamber walls.

[0067] In yet another example, such as Figure 9As shown, the target component 230 may include a shield 262 associated with the indirectly heated cathode 214. In this example, the target heater 242 includes a filament 212, which is further configured to heat the shield 262. For example, the shield 262 surrounds or otherwise surrounds the indirectly heated cathode 214 and may be at the same potential as the indirectly heated cathode, or at ground potential or return potential. Furthermore, the target component 230 of this disclosure may be advantageously heated to a high temperature to facilitate etching of the target material 112 therefrom via interaction with the aforementioned etchant gas (e.g., increasing the etching rate), whereby the heating of the target component is independent of the heat associated with the plasma formed in the arc chamber. In some examples, the target heater 242 is configured to heat the target component 230 above temperatures achievable by plasma alone. For example, the target heater 242 may be configured to selectively heat the target component 230 to a high temperature of approximately 500°C-1000°C. In other examples, the target heater 242 may be configured to selectively heat the target component 230 to a high temperature exceeding 1000°C.

[0068] According to yet another exemplary aspect of this disclosure, a method for controlling Figure 10 The method 300 using an ion source, thus the various features discussed above can be used to practice the method. It should be noted that although the exemplary method is illustrated and described herein as a series of actions or events, it should be understood that the invention is not limited to the illustrated order of these actions or events, as some steps may occur in a different order and / or simultaneously with other steps besides those shown and described herein, according to the invention. Furthermore, not all steps shown are necessary to implement the method according to the invention. Moreover, it should be understood that the method can be implemented in conjunction with the systems shown and described herein, or in conjunction with other systems not shown.

[0069] According to one example, method 300 includes: in action 302, forming a plasma within an arc chamber, thereby defining plasma thermal emission. In action 304, selectively heating a target component disposed within the arc chamber. The target component comprises a dopant material, as discussed in the various examples above. According to this disclosure, the selective heating of the target component in action 304 is performed independently of the plasma formation in action 302. For example, the selective heating in action 304 may include heating the target component to a predetermined operating temperature prior to forming a plasma within the arc chamber. In another example, the selective heating of the target component in action 304 includes heating the target component to a predetermined operating temperature simultaneously with the formation of a plasma within the arc chamber in action 302. For example, the predetermined operating temperature is higher than a predetermined plasma temperature associated with heating the target component solely by plasma thermal radiation.

[0070] While the invention has been shown and described with respect to one or more specific embodiments, it should be noted that the above embodiments are merely examples of some embodiments for implementing the invention, and the application of the invention is not limited to these embodiments. In particular, with respect to the different functions performed by the components (assemblies, devices, circuits, etc.) described above, unless otherwise specified, the terminology used to describe these components (including references to "device") is intended to correspond to any component that performs the specified function of the described component (i.e., functionally equivalent), even if its structure is not structurally equivalent to the disclosed structure performing that function in exemplary embodiments of the invention. Furthermore, while specific features of the invention may be disclosed only with respect to one of several embodiments, such features may be combined with one or more other features of other embodiments when they may be desirable and advantageous for any given or particular application. Therefore, the invention is not limited to the above-described embodiments, but is intended to be limited only by the appended claims and their equivalents.

Claims

1. An ion source, comprising: An arc chamber, wherein the arc chamber defines a chamber volume; A target material disposed within the chamber volume, wherein the target material comprises a dopant type; An indirect heating cathode, positioned within the chamber volume, wherein the indirect heating cathode is configured to ionize a source gas within the chamber volume, thereby defining a plasma having associated thermal plasma emission; and A target heater configured to selectively heat the target material within the chamber volume independently of plasma thermal emission associated with the plasma.

2. The ion source according to claim 1, wherein, The target heater includes one or more of the following: resistance heating element, induction heating element, quartz halogen heating element, or laser.

3. The ion source of claim 1, further comprising a reflector located within the chamber volume, wherein the reflector includes a reflector axis and a target member, wherein the target member comprises the target material, and wherein the target heater is configured to selectively heat at least a portion of the reflector axis, thereby selectively heating the target member.

4. The ion source according to claim 3, wherein, The reflective polar axis includes a solid portion, wherein the target heater is configured to selectively heat the solid portion by transferring thermal energy thereto.

5. The ion source according to claim 4, wherein, The reflective polar axis also includes a hollow portion, wherein the hollow portion defines a cavity within the reflective polar axis, and wherein the target heater is configured to selectively heat the solid portion by means of heat energy transfer through the cavity.

6. The ion source according to claim 5, wherein, The target heater is positioned within the cavity and includes either a resistance heating element or an induction heating element.

7. The ion source according to claim 5, wherein, The target heater includes one of a quartz halogen heating element and a laser, wherein the target heater is guided toward the solid portion through the cavity.

8. The ion source according to claim 3, wherein, The target component includes a hollow cylinder that generally surrounds at least a portion of the reflective polar axis.

9. The ion source according to claim 3, wherein, The target component includes a reservoir operatively coupled to the reflective polar axis, wherein the reservoir is configured to contain liquid target material therein.

10. The ion source of claim 3, further comprising a power supply configured to electrically bias, electrically levitate, or electrically ground the reflector relative to the arc chamber.

11. The ion source according to claim 10, wherein, The target component is electrically coupled to the power source.

12. The ion source of claim 1, further comprising a target component operatively coupled to the arc chamber, wherein the target component comprises the target material.

13. The ion source of claim 12, further comprising a power source configured to electrically bias, electrically levitate, or electrically ground the target member relative to one or more of the arc chamber, the indirect heating cathode, or the target heater.

14. The ion source according to claim 12, wherein, The target component includes a target cylinder that generally surrounds the indirectly heated cathode.

15. The ion source according to claim 14, wherein, The target heater includes the indirect heating cathode.

16. The ion source according to claim 12, further wherein, The target component includes a reservoir configured to contain liquid target material therein.

17. The ion source according to claim 12, wherein, The target component comprises a solid target material.

18. The ion source according to claim 12, wherein, The arc chamber includes one or more chamber walls, and one or more of the target member and the target heater are operatively coupled to the one or more chamber walls.

19. An ion source, comprising: An arc chamber, wherein the arc chamber defines a chamber volume; An indirect heating cathode is positioned within the chamber volume, wherein the indirect heating cathode is configured to define a plasma within the chamber volume, and wherein the plasma has associated thermal plasma emission. A reflector, positioned substantially opposite the indirectly heated cathode within the cavity volume, wherein the reflector includes a reflector axis and a target component, wherein the target component comprises a dopant material; and A target heater configured to selectively heat at least a portion of the reflective polar axis, thereby selectively heating the target component, wherein the target heater is configured to selectively heat the target component independently of plasma thermal emission associated with the plasma.

20. The ion source according to claim 19, wherein, The target heater includes one or more of the following: resistance heating element, induction heating element, quartz halogen heating element, or laser.

21. The ion source according to claim 20, wherein, The reflective polar axis includes a solid portion, wherein the target heater is configured to selectively heat the solid portion by transferring thermal energy thereto.

22. The ion source according to claim 21, wherein, The reflective polar axis also includes a hollow portion, wherein the hollow portion defines a cavity within the reflective polar axis, and wherein the target heater is configured to selectively heat the solid portion by means of heat energy transfer through the cavity.

23. The ion source according to claim 21, wherein, The target component includes a hollow cylinder that generally surrounds at least a portion of the reflective polar axis.

24. The ion source according to claim 21, wherein, The target component includes a reservoir operatively coupled to the reflective polar axis, wherein the reservoir is configured to contain liquid dopant material therein.

25. The ion source according to claim 21, further comprising one or more chamber walls, wherein, One or more of the target component or the target heater are operatively coupled to the one or more chamber walls.

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