Resonator, linear accelerator configuration, and ion implantation system having a toroidal resonator

Abstract

The apparatus may include a drift tube assembly configured to conduct an ion beam. The drift tube assembly may include a first grounded electrode, an RF drift tube assembly disposed downstream of the first grounded electrode, and a second grounded electrode disposed downstream of the RF drift tube assembly. The RF drift tube assembly may define a triple-gap configuration. The apparatus may include a resonator, the resonator comprising a toroidal coil having a first end connected to a first RF drift tube of the RF drift tube assembly and a second end connected to a second RF drift tube of the RF drift tube assembly.

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates generally to ion implanters, and more particularly to high energy beamline ion implanters. [Background technology]

[0002] Ion implantation is a process of introducing dopants or impurities into a substrate via ion bombardment. An ion implantation system may include an ion source and a series of beamline components. The ion source may include a chamber in which ions are generated. The ion source may also include a power supply and an extraction electrode assembly disposed adjacent to the chamber. The beamline components may include, for example, a mass analyzer, a first acceleration or deceleration stage, a collimator, and a second acceleration or deceleration stage. Much like a series of optical lenses for manipulating a light beam, the beamline components can filter, focus, and manipulate ions or ion beams having specific species, shapes, energies, and / or other qualities. The ion beam may be directed through the beamline components toward a substrate mounted on a platen or clamp.

[0003] Implanters capable of producing ion energies of approximately 1 MeV or greater are often referred to as high-energy ion implanters or high-energy ion implantation systems. One type of high-energy ion implanter is called a linear accelerator or LINAC, in which a series of electrodes configured as a tube conducts the ion beam, accelerating it to increasingly higher energies along the tube series, where the electrodes receive an AC voltage signal. Known (RF) LINACs are driven by an applied RF voltage at frequencies between 13.56 MHz and 120 MHz.

[0004] In known LINACs (for simplicity, the term LINAC as used herein may refer to RF LINACs, which use an RF signal to accelerate an ion beam), an ion beam may be accelerated in multiple acceleration stages to reach a targeted final energy, such as 1 MeV, several MeV, or higher MeV. Each successive stage of the LINAC may receive the ion beam at an increasingly higher energy and accelerate the ion beam to even higher energies.

[0005] Depending on the number of drift tubes (accelerating electrodes), known acceleration stages can employ a so-called double-gap configuration or a so-called triple-gap configuration. The advantage of the triple-gap configuration is that three acceleration gaps are provided within a given acceleration stage, allowing accelerated ions to increase in energy by a maximum increment equal to 4 × ion charge state × maximum RF voltage amplitude generated on the electrodes. For comparison, for the same ion species, a two-gap configuration can accelerate an ion beam to a maximum of 2 × ion charge state × maximum RF voltage amplitude on the accelerating drift tube. Therefore, for a given maximum available drive voltage, a triple-gap configuration can accelerate an ion beam to a target ion energy using fewer acceleration stages than a double-gap configuration.

[0006] While the use of a triple gap configuration within a given acceleration stage may represent a more efficient configuration than a double gap configuration, the size of the LINAC is still relatively long, due in part to the large resonator components required to generate the high rf voltage on the drift tube (accelerating electrode).

[0007] It is with respect to these and other considerations that the present disclosure is provided. Summary of the Invention

[0008] In one embodiment, an apparatus is provided that includes a drift tube assembly configured to conduct an ion beam. The drift tube assembly may include a first grounded electrode, an RF drift tube assembly disposed downstream of the first grounded electrode, and a second grounded electrode disposed downstream of the RF drift tube assembly. The RF drift tube assembly may thus define a triple-gap configuration. The apparatus may also include a resonator including a toroidal coil, the toroidal coil having a first end connected to a first RF drift tube of the RF drift tube assembly and a second end connected to a second RF drift tube of the RF drift tube assembly.

[0009] In another embodiment, an ion implanter is provided that includes an ion source for generating an ion beam and a linear accelerator for transporting and accelerating the ion beam, the linear accelerator including multiple acceleration stages. A given acceleration stage of the multiple acceleration stages can include an RF power assembly configured to output an RF signal and a drift tube assembly configured to conduct the ion beam and coupled to the RF power assembly, the drift tube assembly defining a triple gap configuration. The given acceleration stage can further include a resonator including a toroidal coil, the toroidal coil having a first end connected to a first RF drift tube of the drift tube assembly and a second end connected to a second RF drift tube of the drift tube assembly.

[0010] In another embodiment, a resonator for a linear accelerator is provided. The resonator may include an RF enclosure and a toroidal coil disposed within the RF enclosure. The toroidal coil may include a first half forming a first coil having a first plurality of turns wound in a first direction and a second half forming a second coil having a second plurality of turns wound in the first direction. Thus, the first half may further include a first end for coupling to a first electrode of the linear accelerator, and the second half may further include a second end for coupling to a second electrode of the linear accelerator. The resonator may also include an exciter coil disposed inside the toroidal coil, the exciter coil having a first leg connected to ground and a second leg coupled to receive RF power. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 illustrates an exemplary apparatus according to an embodiment of the present disclosure. [Figure 2] FIG. 10 provides a detailed front view of an embodiment of a toroidal coil. [Figure 3] 1A-1C are side, perspective, and front views, respectively, of an acceleration stage according to an embodiment of the present disclosure. [Figure 4A] FIG. 1 illustrates an exciter coil according to an embodiment of the present disclosure. [Figure 4B] FIG. 4B illustrates the exciter coil of FIG. 4A within an exemplary toroidal coil. [Figure 4C] FIG. 1 illustrates an embodiment of a tuner for a resonator, according to an embodiment of the present disclosure. [Figure 4D] FIG. 4D shows the dependence of the resonant frequency for the tuner structure of FIG. 4C. [Figure 5A] FIG. 10 illustrates electrical characteristics of a toroidal resonator coil employed as a resonator in a triple gap configuration, according to an embodiment of the present disclosure. [Figure 5B]FIG. 10 illustrates electrical characteristics of a toroidal resonator coil employed as a resonator in a triple gap configuration, according to an embodiment of the present disclosure. [Figure 5C] FIG. 10 illustrates electrical characteristics of a toroidal resonator coil employed as a resonator in a triple gap configuration, according to an embodiment of the present disclosure. [Figure 5D] FIG. 10 illustrates electrical characteristics of a toroidal resonator coil employed as a resonator in a triple gap configuration, according to an embodiment of the present disclosure. [Figure 5E] 10A-10C present a simulation of the electromagnetic characteristics of a resonator coil configured in accordance with an embodiment of the present disclosure. [Figure 6] 1A and 1B illustrate alternative embodiments of a toroidal coil for use as a resonator, according to different embodiments of the present disclosure. [Figure 7] FIG. 6C illustrates the dependence of coil tube diameter versus tube length for the coil embodiment shown in FIG. 6B. [Figure 8] 1A-1C are side, perspective, and front views, respectively, of a toroidal coil according to an embodiment of the present disclosure. [Figure 9] 1A and 1B illustrate alternative configurations of a toroidal resonator according to different embodiments of the present disclosure. [Figure 10] FIG. 1 shows a schematic diagram of an ion implanter apparatus according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0012] The drawings are not necessarily to scale. The drawings are representational only and do not depict specific parameters of the present disclosure. The drawings depict exemplary embodiments of the present disclosure and therefore are not to be considered limiting in scope. In the drawings, like numbering represents like elements.

[0013] Apparatus, systems, and methods according to the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the systems and methods are shown. The systems and methods may be embodied in many different forms and are not to be construed as limited to the embodiments set forth herein. Instead, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the systems and methods to those skilled in the art.

[0014] Terms such as "top," "bottom," "upper," "lower," "vertical," "horizontal," "lateral," and "vertical" may be used herein to describe the relative placement and orientation of components and their components of semiconductor manufacturing devices with respect to the geometry and orientation of those components as they appear in the figures. The terms may include the specifically mentioned words, derivatives thereof, and words of similar import.

[0015] As used herein, elements or operations described in the singular and preceded by the word "a" or "an" are understood to include the potential plural of elements or operations. Furthermore, references to "one embodiment" of the present disclosure are not intended to exclude the existence of additional embodiments that also incorporate the recited features.

[0016] Provided herein are approaches for improving high-energy ion implantation systems and components based on beamline architecture, particularly linear accelerator-based ion implanters. For brevity, ion implantation systems are sometimes referred to herein as "ion implanters." Various embodiments involve novel approaches that provide the ability to flexibly adjust the effective drift length within the acceleration stage of a linear accelerator.

[0017] 1 illustrates an exemplary apparatus in a first configuration according to an embodiment of the present disclosure. The apparatus 100 represents an acceleration stage including a drift tube assembly 102 and an associated resonator 110 for accelerating an ion beam 104 in a linear accelerator. As shown in FIG. 10 , described below, the apparatus 100 may be implemented in multiple acceleration stages of a linear accelerator 314 for accelerating an ion beam 306 in an ion implanter 300.

[0018] 1, drift tube assembly 102 includes an upstream grounded drift tube and a downstream grounded drift tube, labeled similarly as grounded drift tube electrode 102B. Drift tube assembly 102 further includes a pair of RF drift tube electrodes, labeled RF drift tube electrode 102A, separated by a gap. Collectively, RF drift tube electrode 102A and grounded drift tube electrode 102B define a triple gap configuration.

[0019] The resonator 110 includes an rf enclosure (can) 112 for housing a toroidal coil 114 and forming an electrical oscillating circuit through the generated coil-enclosure capacitance. The toroidal coil 114 and similar resonator coils are described in detail in the following embodiments. Briefly, FIG. 2 presents a detailed front view of an embodiment of the toroidal coil 114. As used herein, the term "toroidal coil" may refer to two separate coils configured together to define a toroidal shape, where each of the separate coils may form a portion of the toroidal shape, such as a similar half of a toroid.

[0020] As shown in FIG. 2, the toroidal coil 114 includes multiple loops or turns. The toroidal coil 114 includes two coils configured as two halves, each with N turns, constructed from a suitable conductor, such as copper tubing. As shown in FIG. 2, the turns of each half of the toroidal coil 114 are wound in the same direction. At the upper portion of the toroidal coil 114, the two ends of the toroidal coil 114 are extended by a length 10 and threaded through openings in the RF enclosure (can) to allow for further integration in the enclosure and separate connection to the two separate powered RF drift tube electrodes, as described above. At the bottom, the loops of the toroidal coil 114 are connected to the grounded can wall.

[0021] The toroidal coil 114 is powered by an exciter coil 116 located symmetrically between the grounded legs of the toroidal coil 114. An insulating sleeve 118 ensures electrical isolation between the powered legs of the exciter coil and the grounded can wall. The exciter coil 116 is configured to receive RF power as part of an RF power assembly, shown as an RF circuit 124, which includes an RF generator 120 and an impedance element 122. The resonator 110 further includes a tuner 130, which may be configured as a capacitive structure, as described in more detail below.

[0022] Apparatus 100 differs from known triple gap accelerator stages in that resonator 110 supplies voltage to drift tube assembly 102 via a toroidal coil 114, as opposed to the solenoidal (or helical) coil of known triple gap accelerator stages. As will be explained in more detail with respect to Figures 5A-5D, the toroidal coil resonator structure of Figure 1 benefits from the fact that the magnetic field lines are contained inside the toroidal coil 114, thereby avoiding leakage of field lines outside of the toroidal coil 114 and therefore reducing induced eddy currents in the resonator's rf enclosure 112.

[0023] 3A, 3B, and 3C show side, perspective, and front views, respectively, of an acceleration stage 200 according to an embodiment of the present disclosure. The acceleration stage includes a drift tube electrode assembly configured in a triple-gap configuration within an ion beam housing 126, and an insulating holder 128. The acceleration stage 200 further includes a resonator 210 including the toroidal coil 114 described above. The resonator 210 further includes a tuner 130, which comprises a tuner body having first and second portions disposed along a first side and a second side of the toroidal coil 114, respectively. Details of an embodiment of the tuner 130 are shown in FIG. 4C and are described in detail below. Briefly, the tuner 130 may be movable along a major axis of the toroidal coil 114, which is shown as the x-axis of the illustrated Cartesian coordinate system. Movement of the tuner 130 along the x-axis may change the capacitance of the electrical RLC circuit defined by the resonator 210 so that the resonant frequency of the resonator 210 may be tuned.

[0024] 4A shows an exciter coil 116, while FIG. 4B shows the exciter coil 116 disposed within the toroidal coil 114, according to an embodiment of the present disclosure. The exciter coil 116 may have a first leg (right leg) connected to ground and a second leg (left leg) coupled to an RF power assembly. As shown in FIG. 4A, the leg of the exciter coil 116 coupled to the RF power assembly may be insulated from the RF enclosure 112 by an insulating sleeve 118.

[0025] In various embodiments, the exciter coil 116 is a single-turn loop fabricated from metal tubing, such as copper tubing for fluid cooling. The loop diameter d can be configured to be approximately equal to the minor radius of the toroidal coil 114. The angular opening angle θ can be between 15 and 20 degrees and is set depending on the required spatial separation to prevent arcing to the grounded leg of the toroidal coil 114. As also shown in Figures 3A and 3B, to maximize the mutual coupling coefficient M between the exciter coil and the toroidal coil, the exciter coil plane (in this case the XY plane) can be configured perpendicular to the azimuthal axis of the toroid defined by the toroidal coil 114, centered on that axis, and positioned midway between the last grounded side loops of the toroid halves.

[0026] 4C, an embodiment of the tuner 130 is shown, including first and second halves, designated as crown 130A, configured to flank the toroidal coil 114. In this embodiment, crown 130A is configured as a toroidal crown similar to the shape of the toroidal coil 114. A cross-shaped holder 130B is secured to each half, but also to a rod 130C. The rod 130C may be mounted on a guide stage (not shown) and threaded through the RF enclosure 112. The rod 130C may be driven from outside the RF enclosure 112 by a mechanism such as a motorized linear stage, which may translate the rod 130C along the x-axis. In one embodiment, to maximize the tuning range, the radius of curvature of crown 130A may be set equal to the minor radius of the torus forming the toroidal coil 114; in one embodiment, the height h of crown 130A may be slightly greater than 2r, the minor radius of the toroid. The tuner 130 can be set to ground potential so that the toroidal coil-to-toroidal crown assembly forms a system or electrical circuit formed from two capacitors connected in parallel. As the distance between the coil and crown increases, the capacitance decreases, and therefore the resonant frequency increases.

[0027] In various non-limiting embodiments, the characteristics of the toroidal resonator are designed so that the operating resonant frequency matches a preferred RF power supply or rf generator operating frequency, such as 13.56 MHz. Because the cavity housing the toroidal coil forms an RLC circuit, the circuit f0=1 / (2π√LC), (1) oscillates at some frequency f0 with a value at resonance given by where L is the inductance of the coil and C is the capacitance of the system.

[0028] 4D, there is shown the dependence of the resonant frequency for the tuner structure of FIG. 4C as a function of varying position of crown 130A. As shown in FIG. 4D, for a translation of 50 mm, from x=100 mm to x=150 mm from the azimuthal plane (Oyz), tuner 130 produces a tuning range of over 1.5 MHz around the desired frequency of 13.56 MHz.

[0029] 5A-5D, electrical characteristics of a toroidal resonator coil employed as a resonator in a triple-gap configuration are shown, according to an embodiment of the present disclosure. FIG. 5A shows the rf current (current indicated by the black arrow) traveling through the exciter coil 116 at a given instant during an rf cycle. Rf power applied to the input of the exciter coil 116 generates an rf current 152, which in turn generates a local, time-varying magnetic field. As shown in FIG. 5B, the mutual coupling between the exciter coil 116 and the toroidal coil 114 allows magnetic flux lines 154 to close through the volume of the toroidal coil 114. As rf power is transferred from the rf generator through the exciter coil to the electrical oscillator circuit, Magnetic energy in the toroidal coil 114 TIFF0007775315000001.tif24170 (where B is the magnetic field strength in the coil and μ0 is the magnetic permeability of vacuum) shows the electrostatic energy TIFF0007775315000002.tif21170 (ε is the dielectric permittivity of vacuum, and E is the electrostatic field at the end of the toroidal coil 114). The voltage generated at the RF drift tube electrode 102A generates electrostatic equipotential lines 156 in the three gaps between the RF drift tube electrode 102A and the grounded drift tube electrode 102B, and the electric field vectors 158 are shown in FIG. 5D. As is known, the electric field thus formed oscillates depending on the frequency of the applied RF signal. By applying the correct timing of ion arrival in a pulsed or bunched ion beam at the entrance to the acceleration gap, ions can acquire an energy equal to up to four times their product charge times the RF voltage amplitude.

[0030] FIG. 5E presents a simulation of the electromagnetic characteristics of a resonator coil configured according to an embodiment of the present disclosure. In the figure, B(t) represents the variable magnetic field lines in the resonator coil, while V(t) is a variable rf voltage on a first powered electrode coupled to one end of the resonator coil, and V(t) is a variable rf voltage on a second powered electrode coupled to the second end of the resonator coil. The temporal evolution of the magnetic field lines and the rf voltage on the electrodes is described by an rf phase equal to 2πf0t, where t is the elapsed time. The magnetic field lines may represent the magnetic flux passing through the volume of the toroidal coil at a given instant. For one half of an rf cycle, the magnetic flux is oriented in one direction, e.g., clockwise, and for the next half-cycle, the magnetic flux is oriented counterclockwise.

[0031] As can be seen, there is a phase difference of π / 2 radians (equivalent to 90 degrees) between the magnetic field and the voltage on the electrodes. According to equations (2) and (3), the magnetic energy is 0 when the electrostatic energy is at a maximum, and vice versa. There is also a phase difference of π radians between the voltages on the powered electrodes, so when the voltage on one electrode is +Vmax, the voltage on the other electrode is -Vmax.

[0032] 6A-6B and 7 illustrate alternative embodiments of a toroidal coil for use as a resonator according to different embodiments of the present disclosure. The toroidal coil 114A in FIG. 6A can be constructed from a conductive tube having a constant diameter (meaning a non-varying diameter), where the diameter is shown as φ for simplicity of construction, and the pitch between adjacent turns in the inner portion of the toroidal coil 114A is defined as p. Because RF current through the toroidal coil 114A can be limited to a skin depth of less than 20 micrometers for frequencies in the 13.56 MHz range, the wall thickness of the conductive tube need not be thicker than 50 micrometers, 100 micrometers, or so. However, tube walls several millimeters thick are used to provide mechanical robustness and prevent mechanical vibrations in the coil.

[0033] The toroidal coil 114B of FIG. 6B may be constructed from an electrically conductive tube having a continuously variable diameter, with the outer tube diameter φ along the outer surface of the toroidal coil 114B having a first dimension and the inner tube diameter φ' along the inner surface of the toroidal coil 114B having a second dimension smaller than the first dimension. This latter configuration results in a relatively larger value of p compared to the embodiment of FIG. 6A, resulting in a relatively smaller electric field between adjacent turns of the toroidal coil 114B. This lower electric field may help avoid arcing. In certain embodiments, the diameter of the tube may continuously decrease as the tube bends toward the inner portion of the toroidal coil 114C, resulting in the tube having a minimum diameter at the inner surface of the toroidal coil, thereby increasing the pitch to a larger value p'. Furthermore, the larger pitch means a smaller inter-loop capacitance and a resulting higher quality (Q) factor for the oscillator circuit. TIFF0007775315000003.tif18170

[0034] It should be noted that in variations of the above-described embodiments, the shape of the individual turns of the toroidal coil may be characterized by an elliptical cross-section, such as a circular cross-section. As shown in FIG. 7, a tube of continuously variable diameter may be used, with a maximum diameter d at the outermost position of the coil, with a periodicity of 2πr along the tube length. max and has a minimum diameter d min A tube having a .mu.m diameter is used to construct the coil shown in FIG. 6B.

[0035] 8A, 8B, and 8C show side, perspective, and front views, respectively, of a toroidal coil 114C according to an embodiment of the present disclosure. In this example, the toroidal coil is characterized by coil turns that define a D-shaped cross section. Given the same major diameter and the same coil turn diameter, this D-shaped cross section increases the overall volume within the toroidal coil compared to a toroidal coil having coil turns defined by a circular cross section.

[0036] 9A and 9B illustrate alternative configurations of a toroidal resonator according to different embodiments of the present disclosure. Due to its azimuthal half-symmetry, the toroidal geometry is versatile for configuration in different configurations, allowing for minimization of the resonator footprint. Configuration 250 illustrates a housing 212 with a beam direction (along the Z axis) moving in and out of the plane of the figure. Configuration 260 also illustrates a housing 212 with a beam direction (along the Z axis) moving in and out of the plane of the figure. As shown, the axis of the toroidal coil of resonator 210 is aligned along the X axis. When the resonator is aligned along the Z axis, configuration 250 shown in FIG. 9A is desirable (the height of the can resonator is generally less than the diameter). Conversely, when the resonator is distributed in both the Z and azimuthal directions, configuration 260 shown in FIG. 9B is desirable.

[0037] FIG. 10 shows a schematic of an apparatus according to an embodiment of the present disclosure. The ion implanter 300 includes a linear accelerator 314. The ion implanter 300 may represent a beamline ion implanter, although some elements are not shown for clarity of illustration. The ion implanter 300 may include an ion source 302 and a gas box 307, as known in the art. The ion source 302 may include an extraction system including extraction components and a filter (not shown) for generating an ion beam 306 at a first energy. Examples of suitable ion energies for the first ion energy range from 5 keV to 300 keV, although embodiments are not limited in this context. To form a high-energy ion beam, the ion implanter 300 includes various additional components for accelerating the ion beam 306.

[0038] The ion implanter 300 may include an analyzer 310 that functions to analyze the ion beam 306, as in known devices, by modifying the trajectory of the ion beam 306, as shown. The ion implanter 300 may also include a buncher 312 and a linear accelerator 314 (shown in dashed lines) disposed downstream of the buncher 312, configured to accelerate the ion beam 306 to form a high-energy ion beam 315 having an ion energy greater than that of the ion beam 306 before entering the linear accelerator 314. The buncher 312 may receive the ion beam 306 as a continuous ion beam and output the ion beam 306 as a bunched ion beam to the linear accelerator 314. The linear accelerator 314 may include multiple acceleration stages, represented by resonators 110 configured in series, as shown. In various embodiments, the ion energy of the high-energy ion beam 315 may represent or approximately represent the final ion energy for the ion beam 306. In various embodiments, the ion implanter 300 may include additional components, such as a filter magnet 316, a scanner 318, and a collimator 320, the general functions of which are well known and will not be described in further detail here. Accordingly, a high-energy ion beam, represented by high-energy ion beam 315, may be delivered to an end station 322 for processing a substrate 324. A non-limiting energy range for the high-energy ion beam 315 includes 500 keV to 10 MeV, and the ion energy of the ion beam 306 is incrementally increased through various acceleration stages of a linear accelerator 314. According to various embodiments of the present disclosure, the acceleration stages of the linear accelerator 314 are powered by a resonator 110, the design of which may follow the embodiments of FIGS. 1-9B.

[0039] In view of the above, the present disclosure provides at least the following advantages: For one, a smaller resonator footprint, and therefore a smaller LINAC footprint, can be achieved using the toroidal coil resonator of the present embodiment compared to known LINAC-based ion implanters; and, the present embodiment further provides the advantage of a higher quality factor Q of the oscillator circuit compared to solenoid-type resonators.

[0040] Although several embodiments of the present disclosure have been described herein, the disclosure is not limited thereto, as it is to be understood that the disclosure is as broad as the art will permit, and the specification may be read in a similar manner. Accordingly, the above description is not to be construed as limiting. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.

Claims

1. An apparatus, comprising:

1. A drift tube assembly configured to conduct an ion beam, the drift tube assembly comprising: a first ground electrode; an RF drift tube assembly disposed downstream of the first grounded electrode and defining a triple gap configuration; a second ground electrode disposed downstream of the RF drift tube assembly; a drift tube assembly comprising: a resonator comprising a toroidal coil, the toroidal coil having a first end connected to a first RF drift tube of the RF drift tube assembly and a second end connected to a second RF drift tube of the RF drift tube assembly; Equipped with 10. The apparatus, wherein the resonator further comprises a tuner, the tuner comprising a tuner body disposed in a first portion and a second portion along a first side of the toroidal coil and a second side of the toroidal coil, respectively.

2. 2. The apparatus of claim 1, wherein the toroidal coil has a first half and a second half, the first half having a first number of turns equal to a second number of turns of the second half.

3. The apparatus of claim 1 , wherein the toroidal coil defines an elliptical cross section.

4. The apparatus of claim 1 , wherein the toroidal coil defines a D-shaped cross section.

5. The apparatus of claim 1 , wherein the toroidal coil comprises an electrically conductive tube having a constant diameter.

6. An apparatus, comprising:

1. A drift tube assembly configured to conduct an ion beam, the drift tube assembly comprising: a first ground electrode; an RF drift tube assembly disposed downstream of the first grounded electrode and defining a triple gap configuration; a second ground electrode disposed downstream of the RF drift tube assembly; a drift tube assembly comprising: a resonator comprising a toroidal coil, the toroidal coil having a first end connected to a first RF drift tube of the RF drift tube assembly and a second end connected to a second RF drift tube of the RF drift tube assembly; Equipped with the toroidal coil comprises an electrically conductive tube having a non-uniform tube diameter, an outer tube diameter disposed along an outer surface of the toroidal coil having a first dimension, and an inner tube diameter disposed along an inner surface of the toroidal coil having a second dimension smaller than the first dimension.

7. An apparatus, comprising:

1. A drift tube assembly configured to conduct an ion beam, the drift tube assembly comprising: a first ground electrode; an RF drift tube assembly disposed downstream of the first grounded electrode and defining a triple gap configuration; a second ground electrode disposed downstream of the RF drift tube assembly; a drift tube assembly comprising: a resonator comprising a toroidal coil, the toroidal coil having a first end connected to a first RF drift tube of the RF drift tube assembly and a second end connected to a second RF drift tube of the RF drift tube assembly; an exciter coil disposed inside the toroidal coil, the exciter coil having a first leg connected to ground and a second leg coupled to an RF power assembly; An apparatus comprising:

8. An ion implanter comprising: an ion source for generating an ion beam; a linear accelerator for transporting and accelerating the ion beam; Equipped with the linear accelerator comprises a plurality of acceleration stages, a given acceleration stage of the plurality of acceleration stages comprising: an RF power assembly configured to output an RF signal; a drift tube assembly configured to conduct the ion beam, coupled to the RF power assembly, and defining a triple gap configuration; a resonator comprising a toroidal coil, the toroidal coil having a first end connected to a first RF drift tube of the drift tube assembly and a second end connected to a second RF drift tube of the drift tube assembly; Equipped with 10. The ion implanter of claim 9, wherein the resonator further comprises a tuner, the tuner comprising a tuner body disposed in a first portion and a second portion along a first side of the toroidal coil and a second side of the toroidal coil, respectively.

9. 9. The ion implanter of claim 8, wherein the toroidal coil has a first half and a second half, the first half having a first number of turns equal to a second number of turns in the second half.

10. The ion implanter of claim 8 , wherein the toroidal coil defines an elliptical cross section.

11. 9. The ion implanter of claim 8, wherein the toroidal coil defines a D-shaped cross section.

12. 9. The ion implanter of claim 8, wherein the toroidal coil comprises an electrically conductive tube having a constant diameter.

13. An ion implanter comprising: an ion source for generating an ion beam; a linear accelerator for transporting and accelerating the ion beam; Equipped with the linear accelerator comprises a plurality of acceleration stages, a given acceleration stage of the plurality of acceleration stages comprising: an RF power assembly configured to output an RF signal; a drift tube assembly configured to conduct the ion beam, coupled to the RF power assembly, and defining a triple gap configuration; a resonator comprising a toroidal coil, the toroidal coil having a first end connected to a first RF drift tube of the drift tube assembly and a second end connected to a second RF drift tube of the drift tube assembly; Equipped with 1. The ion implanter of claim 1, wherein the toroidal coil comprises an electrically conductive tube having a non-uniform tube diameter, an outer tube diameter disposed along an outer surface of the toroidal coil having a first dimension, and an inner tube diameter disposed along an inner surface of the toroidal coil having a second dimension smaller than the first dimension.

14. An ion implanter comprising: an ion source for generating an ion beam; a linear accelerator for transporting and accelerating the ion beam; Equipped with the linear accelerator comprises a plurality of acceleration stages, a given acceleration stage of the plurality of acceleration stages comprising: an RF power assembly configured to output an RF signal; a drift tube assembly configured to conduct the ion beam, coupled to the RF power assembly, and defining a triple gap configuration; a resonator comprising a toroidal coil, the toroidal coil having a first end connected to a first RF drift tube of the drift tube assembly and a second end connected to a second RF drift tube of the drift tube assembly; Equipped with 10. The ion implanter of claim 1, further comprising an exciter coil disposed inside the toroidal coil, the exciter coil having a first leg connected to ground and a second leg coupled to the RF power assembly.

15. 1. A resonator for a linear accelerator, the resonator comprising: an RF enclosure; a toroidal coil disposed within the RF enclosure, the toroidal coil comprising: a first half forming a first coil having a first plurality of turns wound in a first direction; a second half forming a second coil having a second plurality of turns wound in the first direction; and Equipped with a toroidal coil, the first half further comprising a first end for coupling to a first electrode of the linear accelerator, and the second half further comprising a second end for coupling to a second electrode of the linear accelerator; an exciter coil disposed inside the toroidal coil, the exciter coil having a first leg connected to ground and a second leg coupled to receive RF power; A resonator comprising:

16. The resonator of claim 15 , wherein the toroidal coil defines an elliptical cross section.

17. The resonator of claim 15 , wherein the toroidal coil defines a D-shaped cross section.

18. 16. The resonator of claim 15, wherein the toroidal coil comprises an electrically conductive tube having a non-uniform tube diameter, an outer tube diameter disposed along an outer surface of the toroidal coil having a first dimension, and an inner tube diameter disposed along an inner surface of the toroidal coil having a second dimension smaller than the first dimension.

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