RF quadrupole particle accelerator

Abstract

The apparatus may include a drift tube assembly defining a triple gap configuration and arranged to accelerate and transmit an ion beam along a beam path, the apparatus may include a resonator for outputting an RF signal to the drift tube assembly, and an RF quadrupole triplet connected to the drift tube assembly and arranged circumferentially around the beam path.

Description

[Technical field]

[0001] This disclosure relates generally to ion implanters, and more particularly to high energy beamline ion implanters. [Background technology]

[0002]

[0002] Ion implantation is a process of introducing dopants or impurities into a substrate through 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 located near 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. Like a series of optical lenses for manipulating a beam of light, the beamline components can filter, focus, and manipulate ions or ion beams having a particular species, shape, energy, and / or other properties. The ion beam can pass through the beamline components and be directed toward a substrate or wafer mounted on a platen or clamp.

[0003]

[0003] Implanters capable of producing ion energies of about 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 arranged as a tube guides and accelerates the ion beam along the series of tubes to increasingly higher energies. The electrodes then receive a power voltage signal. Known LINACs are driven by RF voltages at frequencies ranging from 13.56 MHz to 120 MHz.

[0004]

[0004] One problem with the operation of RF linac ion implanters is that during acceleration of the ion beam, the ion beam splits into ion fluxes along the propagation direction (Z direction) and the ion fluxes have a natural tendency to spread out in both lateral directions (X and Y directions) as well as longitudinal directions (Z direction, or equivalently in time). Known methods for focusing ions are generally complicated and may require unreasonably long acceleration stages to focus the accelerating ion flux.

[0005]

[0005] In some approaches, lateral focusing of ions can be achieved by adding DC quadrupoles. These DC quadrupoles may be added at various stages along the linac, which include drift tube electrodes used to accelerate the ion flux. Such DC quadrupoles can be fabricated as electrostatic or magnetic components that apply a DC quadrupole field to the passing ion beam. Adding these DC quadrupoles to the linac necessarily adds cost, size, and complexity to the beamline and associated control systems.

[0006]

[0006] The present disclosure is presented with respect to these considerations and others. Summary of the Invention

[0007] In one embodiment, an apparatus is provided. The apparatus may include a drift tube assembly defining a triple gap configuration and arranged to accelerate and transmit an ion beam along a beam path. The apparatus may include a resonator for outputting an RF signal to the drift tube assembly, and an RF quadrupole triplet connected to the drift tube assembly and arranged circumferentially around the beam path.

[0008]

[0008] In another embodiment, an ion implanter may include an ion source for generating a continuous ion beam, and a buncher disposed downstream of the ion source and disposed to convert the continuous ion beam into a bunched ion beam. The ion implanter may include a linear accelerator, the linear accelerator being downstream of the buncher and comprising a plurality of acceleration stages. A given acceleration stage of the plurality of acceleration stages may include a drift tube assembly, the drift tube assembly comprising a plurality of drift tubes, defining a triple gap configuration, and disposed to accelerate the bunched ion beam along the beam path. The given acceleration stage may include a resonator for outputting an RF signal to the drift tube assembly, and an RF quadrupole triplet connected to the drift tube assembly and disposed circumferentially around the beam path.

[0009]

[0009] In a further embodiment, an apparatus may include a drift tube assembly including a plurality of drift tubes arranged to accelerate and transmit an ion beam along a beam path. The apparatus may include a resonator for outputting an RF signal to the drift tube assembly, and a quadrupole arrangement arranged circumferentially around the beam path. The quadrupole arrangement may be integrated into a surface of the plurality of drift tubes of the drift tube assembly, where the quadrupole arrangement defines a sinusoidal or elliptical shape. [Brief description of the drawings]

[0010] [Figure 1] 1 illustrates an exemplary apparatus according to an embodiment of the present disclosure. [Diagram 2]

[0011] 1 illustrates another exemplary apparatus according to an embodiment of the present disclosure. [Diagram 3]

[0012] 1 illustrates a further exemplary apparatus according to an embodiment of the present disclosure. [Figure 4]

[0013] 1 illustrates yet another exemplary apparatus according to an embodiment of the present disclosure. [Diagram 5]

[0014] 1 shows details of device geometry according to an embodiment of the present disclosure. [Figure 6A]

[0015] 6A and 6B depict ion beam focusing geometries according to embodiments of the present disclosure. [Figure 6B] 6A and 6B depict ion beam focusing geometries according to embodiments of the present disclosure. [Figure 7A]

[0016] 1 illustrates another exemplary apparatus according to a further embodiment of the present disclosure. [Figure 7B]

[0017] 7B and 7C present simulation results showing ion beam focusing as a function of gap size in an apparatus configured according to an embodiment of the present disclosure. [Figure 7C] 7B and 7C present simulation results showing ion beam focusing as a function of gap size in an apparatus configured according to an embodiment of the present disclosure. [Figure 8]

[0018] 1 illustrates an exemplary ion implanter according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011]

[0019] The drawings are not necessarily to scale. The drawings are merely representational and are not intended to represent specific parameters of the present disclosure. The drawings are intended to illustrate exemplary embodiments of the present disclosure and therefore should not be considered limiting in scope. In the drawings, like numbers represent like elements.

[0012]

[0020] 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 consistent and complete, and will fully convey the scope of the systems and methods to those skilled in the art.

[0013]

[0021] With respect to the geometries and orientations of components of semiconductor manufacturing devices as they appear in the drawings, terms such as "top," "bottom," "upper," "lower," "vertical," "horizontal," "lateral," and "longitudinal" may be used herein to describe the relative placement and orientation of these components and their constituent parts. Terminology includes the words specifically mentioned, derivatives thereof, and words of similar import.

[0014]

[0022] As used herein, elements or operations recited in the singular and preceded by the word "a" or "an" are understood to include a plurality of elements or operations. Furthermore, references to "one embodiment" of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.

[0015]

[0023] Approaches are provided herein for improved high energy ion implantation systems and components based on a baseline architecture, particularly linear accelerator based ion implanters. For brevity, the ion implantation system may also be referred to herein as an "ion implanter." Various embodiments involve novel approaches that provide improved control of the ion beam during acceleration through the acceleration stage of the linear accelerator, and in particular improved ion beam focusing capabilities.

[0016]

[0024] FIG. 1 illustrates an exemplary apparatus according to an embodiment of the present disclosure. The apparatus 100 may represent an acceleration stage of a linear accelerator, such as a linear accelerator disposed within an ion implanter, as described below with respect to FIG. 8. The apparatus 100 includes a drift tube assembly 104 and associated components for accelerating an ion beam in the acceleration stage of the linear accelerator. In particular, the apparatus 100 defines a triple gap configuration, in which the ion beam is directed through three acceleration gaps within the apparatus 100. The apparatus 100 is thus arranged to transmit and accelerate a bunched ion beam, illustrated as ion beam 130, along a beam path 140 that extends along a central region of the apparatus 100.

[0017]

[0025] The drift tube assembly 104 is formed of a plurality of drift tubes including a first grounded drift tube 112, a second grounded drift tube 118, a first powered drift tube 114 disposed downstream of the first grounded drift tube 112, and a second powered drift tube 116 disposed downstream of the first powered drift tube 114. The drift tube assembly 104 is coupled to a resonator 102 arranged to output an RF signal. In the configuration of FIG. 1, both ends of the resonator 102 are connected to the first powered drift tube 114 and the second powered drift tube 116. Thus, when the RF generator 120 supplies RF power to the resonator 102, an RF voltage of a first polarity is generated in the first powered drift tube 114, while an RF voltage of a second opposite polarity is generated in the second powered drift tube 116. The RF voltages generated have a sinusoidal time variation with a phase difference of 180 degrees. This variation means that the voltage at the first powered drift tube 114 is equal but of opposite polarity to the voltage at the second powered drift tube 116. Thus, a time-varying electric field develops across gap 2, which is proportional to twice the instantaneous value of the RF voltage signal and varies according to the frequency of the applied RF voltage signal. Similarly, a time-varying electric field with the same frequency but different amplitude develops across gap 1 between the first grounded drift tube 112 and the first powered drift tube 114, and across gap 3 between the second powered drift tube 116 and the second grounded drift tube 118.

[0018]

[0026] It should be noted that the device 100 is arranged to receive the ion beam 130 as a bunched ion beam. In that case, the ion beam 130 may be a continuous ion beam or bunched by a buncher (not shown) arranged according to known linacs upstream of the device 100. Thus, by appropriately timing the arrival of the bunches of ions of the ion beam 130 in gaps 1, 2 and 3, the ion beam may be accelerated by the electric field generated when the RF voltage generated in the powered electrodes reaches a maximum value and has a positive polarity, i.e. when the voltage drop across the gap is equal to minus one times the amplitude of the voltage for gaps 1 and 3 and minus two times the amplitude of the voltage for gap 2. In this way, a given bunch may be accelerated along the Z axis of a Cartesian coordinate system, generally as shown. At the same time, the bunched ions may tend to defocus in the X and Y directions. To counter this tendency, the device 100 is equipped with a quadrupole arrangement 108. The quadrupole arrangement 108 is connected to the drift tube assembly 104 and is circumferentially disposed around the beam path 140 .

[0019]

[0027] As shown, the quadrupole arrangement 108 is arranged as a triplet. The triplet includes a first quadrupole 108A formed in a downstream portion of the first grounded drift tube 112 and an upstream portion of the first powered drift tube 114. The quadrupole arrangement 108 also includes a second quadrupole 108B formed in a downstream portion of the first powered drift tube 114 and an upstream portion of the second powered drift tube 116. The quadrupole arrangement 108 further includes a third quadrupole 108C formed in a downstream portion of the second powered drift tube 116 and an upstream portion of the second grounded drift tube 118.

[0020]

[0028] A given quadrupole of the quadrupole arrangement 108 includes two pairs of protrusions, where the protrusions of a given pair are disposed on either side of the beam path 140 and connected to a given drift tube. To define the quadrupole geometry, the protrusions may be disposed in the following manner: a first line (see line 152) extending through the first pair of protrusions is rotated 90 degrees about an axis generally defined by the beam path 140 relative to a line (see line 154) extending through the second pair of protrusions. Although illustrated as cylinders, the protrusions may be of any suitable shape according to other embodiments.

[0021]

[0029] It should be noted that the quadrupole arrangement 108 may be formed of a conductive material electrically connected to the drift tube assembly 104, whereby the first quadrupole 108A, the second quadrupole 108B, or the third quadrupole 108C is maintained at the same potential as the drift tube connected to the given quadrupole component. Thus, the quadrupole arrangement 108 forms an RF quadrupole triplet. The RF quadrupole triplet generates a time-varying quadrupole electric field of alternating polarity at the same frequency as the accelerating electric field extending along the Z direction across gaps 1, 2, and 3.

[0022]

[0030] In operation, an ion beam 130 is accelerated through the apparatus 100 and an RF voltage signal is applied to the drift tube assembly 104, causing the quadrupole arrangement 108 to introduce a quadrupole moment in each of gaps 1, 2, and 3 via the first quadrupole 108A, the second quadrupole 108B, and the third quadrupole 108C. These quadrupoles may act to generate a classical balanced quadrupole triplet. According to some embodiments of the present disclosure, the relative lengths (along the Z direction) of gaps 1, 2, and 3, as well as the quadrupole strengths of the gaps, may be adjusted independently of one another to achieve proper focusing of the ion beam 130. In this manner, the same focusing strength may be achieved generally in the X and Y directions, with similar quadrupole strength fields in alternating directions, as indicated by the arrows in FIG. 1. This result may be achieved in particular by optimizing the size of the protrusions forming the respective quadrupoles on each side of Gap 1, Gap 2 and Gap 3.

[0023]

[0031] It should be noted that in the embodiment of FIG. 1, the cylindrical shape of the protrusions forming each quadrupole is not ideal because they exhibit sharp corners. These sharp corners may not be suitable for stability in a high electric field environment, such as when a relatively high electric field is generated across Gap 1, Gap 2, or Gap 3. Such sharp corners may intensify the electric field even in a reduced pressure environment, and may cause electrostatic breakdown. Therefore, in further embodiments, the quadrupoles may be formed using smoother, rounded features.

[0024]

[0032] 2 presents an embodiment showing a drift tube assembly 204 that may be used, such as in the case of the drift tube assembly 104, to accelerate and shape an ion beam, as generally described with respect to FIG. 1. The drift tube assembly 204 is formed of multiple drift tubes, including a first grounded drift tube 212, a second grounded drift tube 218, a first powered drift tube 214 disposed downstream of the first grounded drift tube 212, and a second powered drift tube 216 disposed downstream of the first powered drift tube 214. In this embodiment, a quadrupole arrangement 208 is integrally formed with the drift tube assembly 204. In that case, the quadrupole arrangement 208 is specifically formed by molding portions of the various drift tubes of the drift tube assembly 204.

[0025]

[0033] In particular, the quadrupole arrangement 208 is arranged as a triplet. The triplet includes a first quadrupole 208A formed in a downstream portion of the first grounded drift tube 212 and an upstream portion of the first powered drift tube 214. The quadrupole arrangement 208 also includes a second quadrupole 208B formed in a downstream portion of the first powered drift tube 214 and an upstream portion of the second powered drift tube 216. The quadrupole arrangement 208 further includes a third quadrupole 208C formed in a downstream portion of the second powered drift tube 216 and an upstream portion of the second grounded drift tube 218. Similar to quadrupole arrangement 108, quadrupole arrangement 208 may act to focus an ion beam (not shown) in the X and Y directions, while the ion beam is directed and accelerated along the Z direction through drift tube assembly 204.

[0026]

[0034] In the embodiment of FIG. 2, the first quadrupole 208A, the second quadrupole 208B, and the third quadrupole 208C define a sinusoidal shape as shown. According to some embodiments, the shapes of the various opposing drift tubes may form a complementary fit to one another. In particular, the downstream face of the first grounded drift tube 212 may form a complementary fit to the upstream face of the first powered drift tube 214. Similarly, the downstream face of the first powered drift tube 214 may form a complementary fit to the upstream face of the second powered drift tube 216, while the downstream face of the second powered drift tube 216 forms a complementary fit to the upstream face of the second grounded drift tube 218. In other words, the opposing faces forming each quadrupole fit together like a three-dimensional jigsaw puzzle.

[0027]

[0035] 3 presents an apparatus showing a drift tube assembly 304. The drift tube assembly 304 may be used in the manner of the drift tube assembly 104 or drift tube assembly 204 to accelerate and shape an ion beam, generally as described with respect to FIGS. 1 and 2. The drift tube assembly 304 is formed of a plurality of drift tubes, including a first grounded drift tube 312, a second grounded drift tube 318, a first powered drift tube 314 disposed downstream of the first grounded drift tube 312, and a second powered drift tube 316 disposed downstream of the first powered drift tube 314. In this embodiment, a quadrupole arrangement 308 is integrally formed with the drift tube assembly 304. In that case, the quadrupole arrangement 308 is formed from shaping portions of the various drift tubes of the drift tube assembly 304. Drift tube assembly 304 may be arranged to operate similarly to drift tube assembly 204, except that the shapes of quadrupoles 308A, 308B, and 308C are defined by ellipsoids.

[0028]

[0036] FIG. 4 presents an apparatus showing a drift tube assembly 404. The drift tube assembly 404 may be used as the drift tube assembly 104, drift tube assembly 204, and drift tube assembly 304 to accelerate and shape an ion beam, generally as described with respect to FIGS. 1 and 2. The difference between this embodiment and the previous embodiments is that the drift tube assembly 404 defines a double gap configuration, shown as Gap 1 and Gap 2. The drift tube assembly 404 is formed of multiple drift tubes, including a first grounded drift tube 412, a second grounded drift tube 416, and a powered drift tube 414 disposed between the first grounded drift tube 412 and the second grounded drift tube 416. This drift tube assembly 404 may be coupled to receive RF power from one end of a resonator, as in the known linac double gap configuration. Advantageously, the quadrupole arrangement 408 is defined by a first quadrupole 408A and a second quadrupole 408B that are integrally formed within the various drift tubes and are defined by a sinusoidal shape as in the embodiment of FIG. 2 to provide better X and Y focusing of the ion beam.

[0029]

[0037] FIG. 5 shows the geometric details of a drift tube device with a quadrupole arrangement integrally formed therein, according to an embodiment of the present disclosure. In particular, cross sections through the Z-X plane and through the Z-Y plane are shown. The drift tube device is shown as a drift tube assembly 500. The drift tube assembly 500 includes four electrodes, generally as described above, namely a first grounded drift tube 502, a first powered drift tube 504, a second powered drift tube 506, and a second grounded drift tube 508. The electrodes (drift tubes) are modeled as cylindrical shells of thickness 2*a, which has a value of 20 mm in the non-limiting embodiment of FIG. 5. In each section, the cross-section of the cylindrical shell shows two identical sets of structures. FIG. 5 also provides exemplary equations for defining the surfaces of the electrodes for elliptical or sinusoidal embodiments. In particular, in this non-limiting embodiment, to ensure a smooth transition, the parameter "a" may represent the value of one semi-axis of the ellipse as well as half the thickness (2a) of the cylindrical shell of the drift tube electrodes. The parameter "a" alternatively represents the value of a quarter wavelength in one embodiment of a sinusoidal surface. In the case of an elliptical surface, the value of "b" is independent of the radius "r" and may be varied to generate small / medium / large protrusions that define the quadrupole structure. The physical limit of "b" is the gap length for a given gap in the drift tube assembly.

[0030]

[0038] 6A and 6B depict the geometry of ion beam focusing according to an embodiment of the present disclosure. In particular, 6A and 6B are plots of the beam envelope of an ion beam in the X-Z and Y-Z planes, respectively, developed from a simulation study in which P++ ions are traced under an example of a defocus-focus-defocus (DOFODO) configuration of a drift tube configuration 600 with quadrupole (see FIG. 5). The plots show that in the absence of space charge forces, a circular beam can be focused in both two lateral directions by carefully selecting the RF phase (plot without protrusions). With protrusions, it can be clearly observed that in the X direction, the beam experiences focus, then defocus, then focus (FODOFO), while in the Y direction, the beam experiences defocus, then focus, then defocus (DOFODO). At the end of the triplet, an overall balanced focusing effect is realized towards the exit (see the lower curve at Z=200 mm).

[0031]

[0039] In other embodiments of the present disclosure, the drift tube assembly may be arranged to have a quadrupole in which at least one gap may be adjustable. Because quadrupole strength depends on the length of the gap and the length and size of the protrusions that form the quadrupole, being able to adjust the gap length allows the quadrupole strength to be adjusted without removing or reconfiguring parts of the drift tube assembly.

[0032]

[0040] 7A illustrates another exemplary apparatus according to a further embodiment of the present disclosure. In the apparatus 700, the previously described resonator 102 and RF generator 120 are illustrated and will not be further described. In this apparatus, the drift tube assembly 704 defines a triple gap configuration, illustrated as g1, g2, and g3.

[0033]

[0041] Apparatus 700 includes a cross structure 730, and a support structure 722, an arm 728, an arm 726, and a support structure 724, all of which are mechanically coupled to cross structure 730. Support structure 722 includes a first arm 722A and a second arm 722B. The first arm 722A is mechanically coupled to a first grounded drift tube 712, while the second arm 722B is mechanically coupled to a first portion 714-A of a first powered drift tube couple 714.

[0034]

[0042] The support structure 724 includes a first arm 724A and a second arm 724B. The first arm 724A is mechanically coupled to a second portion 716-B of the second powered drift tube couple 716, while the second arm 724B is mechanically coupled to a second grounded drift tube 718.

[0035]

[0043] The fixed arm 728 is connected to the second portion 714-B of the first powered drift tube couple 714. The fixed arm 726 is connected to the first portion 716-A of the second powered drift tube couple 716.

[0036]

[0044] A quadrupole triplet 708 is formed, including quadrupole 708A, quadrupole 708B, and quadrupole 708C formed in gaps g1, g2, and g3, respectively. According to some embodiments of the present disclosure, arm 728, arm 726, first arm 722A, second arm 722B, first arm 724A, and second arm 724B may be independently movable along the Z axis relative to one another. Their movement allows for independent alteration of g1, g2, and g3. This adjustment of the size of g1, g2, and g3 may be achieved by any suitable means for moving the aforementioned arms, such as external mechanical components, motors, or other components (not shown), without the need to break vacuum in the beamline or replace drift tube components.

[0037]

[0045] By providing an arrangement in which the size of the gaps g1, g2, and g3 may be easily varied, the embodiment of FIG. 7A provides a novel approach to control beam geometry. Although the size of the protrusions for a quadrupole may be fixed, as dictated by the hardware forming a given drift tube / quadrupole assembly (such as drift tube assembly 704), the inventors have discovered that by varying the size of g1, g2, and g3, the focusing strength provided by a given protrusion may be adjusted. In other words, the size (along the Z direction) of one or more of the gaps may be independently adjusted to adjust the focusing strength of the ion beam.

[0038]

[0046] 7B and 7C show an example where the effect of changing the size of one acceleration gap, such as by changing g3, is shown. The illustrated simulation shows that by changing g3, the focusing strength produced by the drift tube / quadrupole assembly changes, resulting in a change in beam size. In particular, FIGS. 7B and 7C are plots of the beam envelope of an ion beam in the X-Z and Y-Z planes, respectively, developed from a simulation study where a simple drift tube assembly 750 is represented diagrammatically by four different blocks (two blocks defining gap g3). In the illustrated simulation, the relative size of gap g3 is adjusted, while the dimensions of the other gaps remain constant. For the particular ion beam condition shown, reducing the size of g3 results in a reduction in the beam width (at 200 mm) in the X direction. For other ion beam conditions, the transit time and other higher order effects may be different due to different mass-to-charge ratios, and the subsequent beam focusing behavior may differ from the results shown in FIGS. 6A and 6B. Notably, while the above results demonstrate the ability to change beam focusing by adjusting the size of just one gap, in further embodiments, the ability to independently vary the size of two or more gaps would provide further beam focusing control.

[0039]

[0047] FIG. 8 illustrates a schematic diagram of an ion implanter according to an embodiment of the present disclosure. The ion implanter 800 includes linac acceleration stages 814-A, 814-B, shown as a linear accelerator 814. The ion implanter 800 may represent a beamline ion implanter, and some elements are not shown for clarity of illustration. The ion implanter 800 may include an ion source 802 and a gas box 807 as known in the art. The ion source 802 may include an extraction system including extraction components and filters (not shown) for generating an ion beam 806 at a first energy. Examples of suitable ion energies for the first ion energy range from 5 keV to 100 keV, although embodiments are not limited in this context. To generate a high energy ion beam, the ion implanter 800 includes various additional components for accelerating the ion beam 806.

[0040]

[0048] The ion implanter 800 may include an analyzer 810 that functions to analyze the ion beam 806 as in known devices by modifying the trajectory of the ion beam 806 as shown. The ion implanter 800 may also include a buncher 812 and a linear accelerator 814 (shown in dashed lines) disposed downstream of the buncher 812. In that case, the linear accelerator 814 is arranged to accelerate the ion beam 806 to generate a high energy ion beam 815, the ion energy of which is higher than the ion energy of the ion beam 806 before entering the linear accelerator 814. The buncher 812 may receive the ion beam 806 as a continuous ion beam and may output the ion beam 806 as a bunched ion beam to the linear accelerator 814. The linear accelerator 814 may include multiple acceleration stages (814-A, 814-B, ..., 814-N (not shown)) disposed in series as shown. In various embodiments, the ion energy of the high energy ion beam 815 may represent the final ion energy or approximately the final ion energy for the ion beam 806. In various embodiments, the ion implanter 800 may include further components such as a filter magnet 816, a scanner 818, a collimator 820, etc. In this case, the general functions of the scanner 818 and the collimator 820 are well known and will not be described in further detail herein. The high energy ion beam represented by the high energy ion beam 815 may then be delivered to a final station 822 for processing a substrate 824. A non-limiting energy range for the high energy ion beam 815 includes 500 keV to 10 MeV. In this case, the ion energy of the ion beam 806 is stepwise increased through various acceleration stages of the linear accelerator 814. According to various embodiments of the present disclosure, one or more of the acceleration stages of the linear accelerator 814 may include a drift tube assembly having an integrated quadrupole arrangement, as detailed with respect to the embodiment of FIGS. 1-7. An advantage provided by the ion implanter 800 is that operation of the integrated quadrupole configuration may improve focusing of the ion beam 815 directed through the linear accelerator 814 .

[0041]

[0049] In view of the above, the present disclosure provides at least the following advantages: First, the integration of a quadrupole triplet into the drift tube assembly provides the ability to independently control the focusing of the ion beam bundle; Second, the provision of a variable length drift tube in the present disclosure provides the flexibility to independently control the quadrupole strength.

[0042]

[0050] Although specific embodiments of the present disclosure are described herein, the present disclosure is not limited thereto, as the present disclosure is as broad as the art will permit, and the present specification can be read in the same manner. Therefore, the above description should not be interpreted as limiting. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.

Claims

1. a drift tube assembly comprising a plurality of drift tubes defining a triple gap configuration and arranged to accelerate and transmit the ion beam along a beam path; a resonator for outputting an RF signal to the drift tube assembly; and an RF quadrupole triplet connected to the drift tube assembly and circumferentially disposed about the beam path, The RF quadrupole triplet comprises: a first quadrupole formed in the upstream portion of the first powered drift tube and in the downstream portion of the first grounded drift tube; a second quadrupole formed in a portion of a second powered drift tube upstream of the downstream portion of the first powered drift tube; and a third quadrupole formed in a portion of a second grounded drift tube upstream of the downstream portion of the second powered drift tube; a downstream face of the first grounded drift tube forms a complementary fit with an upstream face of the first powered drift tube, a downstream face of the first powered drift tube forms a complementary fit with an upstream face of the second powered drift tube, and a downstream face of the second powered drift tube forms a complementary fit with an upstream face of the second grounded drift tube, the opposing faces forming each of the complementary fits fitting together like a three dimensional jigsaw puzzle. Device.

2. 2. The apparatus of claim 1, wherein the drift tube assembly comprises a plurality of drift tubes, and the RF quadrupole triplet is integrally formed within the plurality of drift tubes.

3. The apparatus of claim 1 , wherein the first quadrupole, the second quadrupole, and the third quadrupole define an elliptical shape.

4. The apparatus of claim 1 , wherein the first quadrupole, the second quadrupole, and the third quadrupole define a sinusoidal shape.

5. 2. The apparatus of claim 1 , wherein the drift tube assembly comprises a first powered drift tube couple and a second powered drift tube couple, the triple gap configuration including a first gap between the first grounded drift tube and the first powered drift tube couple, a second gap between the first powered drift tube couple and the second powered drift tube couple, and a third gap between the second powered drift tube couple and the second grounded drift tube, a first length of the first powered drift tube being adjustable and a second length of the second powered drift tube being adjustable.

6. 6. The apparatus of claim 5, wherein a first portion of the first powered drift tube couple and the first grounded drift tube are movable in concert with one another, and a second portion of the second powered drift tube couple and the second grounded drift tube are movable in concert with one another, and the first gap, the second gap, and the third gap do not change when a length of the first powered drift tube or a length of the second powered drift tube change.

7. an ion source for producing a continuous ion beam; a buncher disposed downstream of the ion source and configured to convert the continuous ion beam into a bunched ion beam; and a linear accelerator downstream of the buncher, the linear accelerator comprising a plurality of acceleration stages, a given one of the plurality of acceleration stages comprising: a drift tube assembly comprising a plurality of drift tubes defining a triple gap configuration and arranged to accelerate the bundled ion beam along a beam path; a resonator for outputting an RF signal to the drift tube assembly; and an RF quadrupole triplet connected to the drift tube assembly and circumferentially disposed about the beam path, the RF quadrupole triplet comprising: a first quadrupole formed in the upstream portion of the first powered drift tube and in the downstream portion of the first grounded drift tube; a second quadrupole formed in a portion of a second powered drift tube upstream of the downstream portion of the first powered drift tube; and a third quadrupole formed in a portion of a second grounded drift tube upstream of the downstream portion of the second powered drift tube; a downstream face of the first grounded drift tube forms a complementary fit with an upstream face of the first powered drift tube, a downstream face of the first powered drift tube forms a complementary fit with an upstream face of the second powered drift tube, and a downstream face of the second powered drift tube forms a complementary fit with an upstream face of the second grounded drift tube, the opposing faces forming each of the complementary fits fitting together like a three dimensional jigsaw puzzle. Ion implantation equipment.

8. The ion implanter of claim 7 , wherein said RF quadrupole triplets are integrally formed within said plurality of drift tubes.

9. The ion implanter of claim 7 , wherein the first quadrupole, the second quadrupole, and the third quadrupole define an elliptical shape.

10. The ion implanter of claim 7 , wherein the first quadrupole, the second quadrupole, and the third quadrupole define a sinusoidal shape.

11. 8. The ion implanter of claim 7, wherein the drift tube assembly comprises a first powered drift tube couple and a second powered drift tube couple, the triple gap configuration including a first gap between the first grounded drift tube and the first powered drift tube couple, a second gap between the first powered drift tube couple and the second powered drift tube couple, and a third gap between the second powered drift tube couple and the second grounded drift tube, a first length of the first powered drift tube being adjustable and a second length of the second powered drift tube being adjustable.

12. 12. The ion implanter of claim 11 , wherein a first portion of the first powered drift tube couple and the first grounded drift tube are movable relative to one another, and a second portion of the second powered drift tube couple and the second grounded drift tube are movable relative to one another, and the first gap, the second gap, and the third gap do not change when a length of the first powered drift tube or a length of the second powered drift tube change.

13. a drift tube assembly comprising a plurality of drift tubes arranged to accelerate and transmit the ion beam along a beam path; a resonator for outputting an RF signal to the drift tube assembly; and a quadrupole arrangement circumferentially arranged around the beam path, the quadrupole arrangement being integrated into a surface of the drift tubes of the drift tube assembly and defining a sinusoidal or elliptical shape; Device.

14. 14. The apparatus of claim 13, wherein the drift tube assembly defines a triple gap configuration and the quadrupole arrangement defines an RF quadrupole triplet.

15. The apparatus of claim 13 , wherein the drift tube assembly defines a double gap configuration.

16. 15. The apparatus of claim 14, wherein the drift tube assembly comprises a first powered drift tube couple and a second powered drift tube couple, the triple gap configuration including a first gap between a first grounded drift tube and the first powered drift tube couple, a second gap between the first powered drift tube couple and the second powered drift tube couple, and a third gap between the second powered drift tube couple and a second grounded drift tube, a first length of the first powered drift tube being adjustable and a second length of the second powered drift tube being adjustable.

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