Repeller assembly mounted in arc chamber of ion implanter and arc chamber including repeller assembly

Abstract

A repeller assembly attached to the arc chamber of an ion implantation apparatus. The repeller assembly includes a repeller, a cylindrical insertion member, first and second insulators, a contact member, and a locking member. The repeller has a knob-shaped body and is disposed in the arc chamber on the side opposite to the cathode assembly. The repeller shaft is arranged to extend outward through an opening in the wall of the arc chamber. The repeller shaft has a stepped portion that reduces the diameter of the repeller shaft. The cylindrical insertion member is attached concentrically with the repeller shaft. The first insulator has a collar shape and is attached to the cylindrical insertion member so that the inner shoulder of the first insulator is pressed against the outside of the wall of the arc chamber. The second insulator has a C shape and is attached to the first insulator using its outer flange.

Description

[Technical Field]

[0001] The present invention relates to a repeller assembly for installation within the arc chamber of an ion implanter. More particularly, the present invention relates to the components of the repeller assembly and their configuration, arrangement relative to one another, and placement within an opening in a wall of the arc chamber. Additionally, the present invention relates to an arc chamber that houses the repeller assembly. [Background technology]

[0002] As is known, ion implanters are widely used in the manufacture of semiconductor components to modify various regions of semiconductor wafers by diffusing or implanting positive or negative ions (dopants) into the surface of the semiconductor wafer to create regions with different properties (e.g., conductivity, etc.). These ion implanters include an arc chamber that generates a plasma containing various ion species that are implanted into the surface of the semiconductor wafer.

[0003] One common arc chamber configuration involves a repeller (anticathode) positioned opposite a cathode assembly. During arc chamber operation, the cathode assembly is heated, e.g., by a filament, to emit electrons by thermionic emission. The electrons are accelerated into the arc chamber by a relatively positive arc voltage on the arc chamber walls, and an externally generated magnetic field causes the electrons to spiral into the arc chamber. Typically, the emitter and repeller electrodes are negatively biased relative to the arc chamber walls to confine the emitted electrons. The combined effect of the emitter and repeller electrodes is to concentrate the electrons toward the center of the arc chamber, maximizing their interaction with the dopant gas introduced into the arc chamber via a conduit, resulting in a plasma with desired characteristics.

[0004] During operation, the arc chamber contains numerous molecular species at extremely high temperatures. In this harsh environment, components, including those of the repeller assembly, are subjected to conditions that can severely limit their lifespan or effectiveness. This has resulted in limited effectiveness and / or increased operating costs for the ion implanter. For example, plasma films tend to deposit on components of the repeller assembly, such as the repeller shaft, tubular shield, and insulators. Plasma coating on electrically insulated components, such as the repeller, can result in short circuits within the arc chamber, rendering normal operation of the ion implanter impossible. Therefore, it is desirable to extend the coating process (and corresponding short circuit occurrence) of electrically insulated components by providing an extended, tortuous coating path. Further, other failure modes include, for example, loss of arc chamber gas through the opening in the arc chamber wall where the repeller assembly is mounted, due to the size of the gap between the repeller assembly and the wall opening, as well as between the components of the repeller assembly. Additionally, mechanical or thermal changes can cause the repeller shaft or the repeller itself to move away from its cantilevered position and come into direct contact with the arc chamber wall or liner.

[0005] Several repeller assembly configurations are known in the prior art. In one known configuration, the repeller has a wide portion (flared portion) facing the center of the arc chamber and a narrower shank portion (shank) that extends outside the arc chamber through an opening in an end wall of the arc chamber. To maintain the required electrical insulation, a ceramic insulator is disposed within the arc chamber between the end wall and the repeller.

[0006] A modified configuration is disclosed in U.S. Patent No. 8,796,649. Figure 4 of that patent shows a repeller assembly having a knob-shaped body with an enlarged diameter at one end within the arc chamber and an integral stem that passes through an opening in the end wall of the arc chamber. The stem configuration features a pair of radially protruding collars. A tubular shield is concentrically mounted within the opening in the stem end wall, and includes, among other features, at least one radially inward rib between the collars. An insulator ring surrounding the stem is threaded onto the tubular shield and abuts the end wall. The insulator ring includes a disk-shaped end that abuts against an outer collar on the stem to close the plasma path from the arc chamber through the end wall. Thus, on the one hand, a serpentine gap is defined between the stem and the opening in the end wall of the arc chamber, the tubular shield, and the insulator ring. A lock nut is threaded onto the end of the stem and abuts the insulator ring, holding the anticathode (repeller) cantilevered within the arc chamber.

[0007] A similar repeller assembly is disclosed in Figure 13 of U.S. Patent No. 8,253,334. In this patent, the repeller assembly comprises a repeller, a liner, a tubular shield, an insulator, and a locknut. The stem of the repeller is provided with a pair of spaced-apart annular collars, each radially spaced from the tubular shield to introduce additional obstructions to plasma flow from the arc chamber. Furthermore, the insulator ring is shown to have a disk-shaped end that abuts against the collars to close the plasma path outward from the arc chamber.

[0008] The aforementioned patents provide a tortuous gap / plasma path having a limited length. Additionally, the configuration of the repeller stem creates large gaps between the stem and the opening in the end wall of the arc chamber, and between the tubular shield and the insulator ring.

[0009] Therefore, there remains room for improvement in the construction or design of the repeller assembly to improve the life and effectiveness of the repeller assembly and thereby improve the life and effectiveness of the arc chamber. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] U.S. Patent No. 8,796,649 [Patent Document 2] U.S. Patent No. 8,253,334 Summary of the Invention [Problem to be solved by the invention]

[0011] It is an object of the present invention to provide a repeller assembly that can achieve extended operating times for an ion implanter. Increased operating times have the effect of, among other things, reducing the operating costs of the ion implanter. It is also an object of the present invention to provide a repeller assembly that can achieve high operating efficiency by enabling reduced gas leakage and reduced coating formation. [Means for solving the problem]

[0012] In view of the above and other objects described herein, the invention provides a repeller assembly for installation within an arc chamber of an ion implanter, the repeller assembly including a repeller, a tubular insert member, a first insulator, a second insulator, a contact member, and a locking member. The repeller has a knob-shaped body (knob-shaped body) disposed inside the arc chamber on the opposite side of the arc chamber from the cathode assembly, and a repeller shaft integral with the knob-shaped body, the repeller shaft being disposed so as to extend outside the arc chamber through an opening in the wall of the arc chamber, and at least one step portion narrowing the repeller shaft is provided on the repeller shaft; The cylindrical insert member is attached concentrically to the repeller shaft, the first insulator has an inner shoulder and a collar shape, and is attached to the cylindrical insert so that the inner shoulder of the first insulator is pressed against the outside of the wall of the arc chamber; the second insulator has a cap-nut shape and has an inner flange and an outer flange, the second insulator is attached to the first insulator via the outer flange; The contact member is electrically connected to the repeller shaft, and The locking member is fixed to the repeller shaft so that at least one stepped portion of the repeller shaft is pressed against the inner flange of the second insulator.

[0013] In other words, the technical objective of the present invention is achieved by providing a repeller assembly to be mounted in the arc chamber of an ion implanter. The repeller assembly includes a repeller, a cylindrical insert, at least first and second insulators, an abutment member, and a locking member. The repeller has a nodular body disposed inside the arc chamber on the side opposite the cathode assembly of the arc chamber, and a repeller shaft integral with the body disposed to extend outside the arc chamber through an opening in the wall of the arc chamber. The repeller shaft has at least one stepped portion that narrows the repeller shaft, and the cylindrical insert is mounted concentrically with the repeller shaft. The first insulator has a collar shape and is mounted to the cylindrical insert so that an inner shoulder of the first insulator is pressed against the outside of the wall of the arc chamber. The second insulator has a cap-nut shape and is mounted to the first insulator by its outer flange. The abutment member is electrically connected to the repeller shaft, and the locking member is fixed onto the repeller shaft so that the stepped portion of the repeller shaft is pressed against the inner flange of the second insulator, as described in the first independent claim. The repeller assembly is intended to be mounted in an arc chamber, and the arc chamber itself does not form part of the invention described in the first independent claim. This claim merely describes the interactions between the respective parts (or components). Furthermore, an arc chamber of an ion implanter is provided, in which the repeller assembly described in the claims is mounted and has the features of the arc chamber described in the independent claim.

[0014] Further features and details of the invention are set out in the respective dependent claims and in the following detailed description and drawings. It goes without saying that the features and details described with respect to the repeller assembly of the invention can also be applied to the arc chamber of the invention, and vice versa. Therefore, they are or can be referred to each other when describing the respective aspects of the invention.

[0015] The inventors have discovered that the claimed repeller assembly can provide a more extended and tortuous coating path than the prior art. The above-mentioned prior art patent documents describe a tortuous gap between the repeller stem and each of the opening, the tubular shield, and the insulator ring. However, the length of this tortuous gap is limited by, among other things, the position of the last collar on the repeller stem. In contrast, the claimed repeller assembly minimizes the gap between the repeller stem and the opening in the outer wall of the arc chamber, the tubular insert, and at least the first and second insulators, thereby reducing gas loss from the arc chamber during ion beam operation. As is known, the repeller must be attached to the repeller assembly from inside the arc chamber. Therefore, it is clear that in the prior art repeller assemblies, the size of the opening in the end wall of the arc chamber had to be at least as large as the protruding collar of the stem. Therefore, such repeller stem configurations created large gaps between the stem and the arc chamber end wall opening, the tubular shield, and the insulator ring.

[0016] Furthermore, in the claimed repeller assembly, the repeller shaft can be easily introduced into the repeller assembly, and the repeller and tubular seat can be easily replaced. In the prior art described above, the tubular shield was provided with at least one radially inward rib between each collar of the repeller stem. Therefore, apparently, since the repeller stem and the tubular shield were interrelated, it was sometimes difficult to easily remove both the repeller and the tubular shield from this combination when necessary.

[0017] Therefore, it allows for a longer life of the arc chamber during ion beam operation. Furthermore, the claimed repeller assembly allows for a reduced frequency of maintenance shutdowns within the arc chamber.

[0018] As an advantage of the present invention, the repeller shaft configuration (having at least one step) of the claimed repeller assembly is easier to manufacture and replace (compared to a configuration having two collars), and can be easily introduced through an opening in the wall of the arc chamber to the tubular shield and at least two insulators. As a further advantage of the present invention, the components of the claimed repeller assembly, i.e., at least the repeller, the tubular insert, and at least the first and second insulators, are self-aligning. This is provided by the at least one step repeller shaft and tubular insert configuration and the two insulators. The repeller assembly can automatically align itself when installed through an opening in the wall of the arc chamber. Preferably, when the first insulator is threaded onto the tubular insert, the second insulator is threaded onto the first insulator, and the locking member is threaded onto the end of the shaft, no additional or measuring equipment is required to accurately position and install the components of the repeller assembly within the arc chamber of an ion implanter. The exact distance between the repeller assembly and the cathode assembly can also be automatically aligned.

[0019] The repeller of the claimed repeller assembly has a T-shaped cross section, including an expanded, nodular body and a shaft portion integral with the body, the shaft portion having at least one step portion that narrows the diameter from the nodular body to the end of the shaft portion. If the repeller shaft has two or more step portions, the diameter of the repeller shaft can be narrowed at each step portion. That is, the diameter of the repeller shaft can be gradually reduced with each additional step portion provided on the repeller shaft. The shaft portion is provided on the central axis of the nodular body. The repeller shaft can have only one step portion that narrows the diameter of the repeller shaft toward the end of the repeller shaft, or two or more step portions that narrow the diameter of the repeller shaft toward the end of the repeller shaft. For example, two or more step portions are possible. The length of the repeller shaft depends on the parts (or components) of the repeller assembly aligned along the shaft. Importantly, the repeller shaft passes through all parts of the repeller assembly, and the locking member abuts against the abutment member as the final part at the end of the repeller shaft. The repeller shaft is integral with the repeller body. This means that the repeller body and repeller shaft can be manufactured integrally from the same material as a single part. Such a manufacturing process can be achieved by powder metallurgy manufacturing (pressing powder into the desired shape and sintering it) or by melt metallurgy manufacturing (i.e., manufacturing each part from a melt). Alternatively, the repeller body and repeller shaft can be manufactured as two (or more) parts, which can then be joined by a material joining process, for example, by soldering, welding, etc. In a preferred embodiment, the repeller is manufactured monolithically as a single part. The repeller shaft has a main longitudinal axis direction. If the repeller has a strictly cylindrical shape and has several cylindrical sections or steps, this main longitudinal direction corresponds to the cylindrical axis direction of the repeller.

[0020] Typically, the repeller is made of tungsten (W) or molybdenum (Mo). Preferably, the repeller is made of tungsten. Preferably, the material is as pure as possible, preferably 99.9% by weight. The repeller stem configuration with at least one step facilitates the manufacture of the repeller as compared to the repeller stem configuration with two collars used in the prior art. Furthermore, the shank configuration with at least one step that narrows the diameter of the stem provides the advantage of facilitating the introduction and / or replacement of the repeller from inside the arc chamber through an opening in the wall of the arc chamber relative to the arrangement of the cylindrical insert and at least two insulators. The self-aligning configuration of the claimed repeller assembly allows for accurate positioning and installation of the repeller at a predetermined location within the arc chamber in a user-friendly manner, without the need for additional equipment or measuring devices. This avoids, for example, tilting the repeller, which would otherwise impair workability.

[0021] The cylindrical insert has the shape of a flanged bushing. When the repeller assembly is installed in the arc chamber, the cylindrical insert is positioned concentrically with the repeller shaft within the opening in the arc chamber wall, so that the flanged side of the cylindrical insert is oriented toward the inside of the arc chamber and has a larger diameter than the opening abutting the arc chamber wall. Preferably, the flanged side of the cylindrical insert and the opening in the arc chamber wall are chamfered so that the flange abuts the opening in the arc chamber wall. The bushing of the cylindrical insert is connected to a first insulator on the side opposite the flange, so that an inner shoulder of the first insulator presses against the outside of the arc chamber wall. The cylindrical insert has a larger inner diameter at the flange than at the bushing. When a repeller shaft with two steps is used in the repeller assembly, the first step of the repeller shaft with two steps may be located on the flanged side of the cylindrical insert. The cylindrical insert is preferably made of tungsten or molybdenum. In a different embodiment, the cylindrical insert is made of an electrically insulating material, for example, a high-temperature ceramic material such as Al2O3, allowing the cylindrical insert to function as an insulator. The cylindrical insert is provided with means for holding the first insulator and guiding the repeller shaft toward the second insulator.

[0022] The first insulator has a collar shape that includes an inner shoulder (or inner shoulder) and an outer shoulder (or outer shoulder) in a radial direction (from the inside to the outside, perpendicular to the repeller axis). The inner shoulder is rotated toward the repeller axis, and the outer shoulder is located opposite the inner shoulder. When the claimed repeller assembly is installed in the arc chamber, the first insulator is installed in the cylindrical insert member so that the inner shoulder is pressed against the outside of the arc chamber wall. The first repeller may be provided with a circumferential recess (or a circumferential recess) that faces the inner and outer shoulders of the first repeller (in the direction of the main longitudinal axis of the assembly). This recess extends the coating path / plasma path of the repeller assembly. In a preferred embodiment, the first insulator and the tubular insert are threadedly attached to one another (e.g., screwed) so that the two parts are tightly connected and the inner shoulder of the first insulator is pressed against the outside of the arc chamber wall.

[0023] The second insulator has a cap-nut-like structure, including an inner flange and an outer flange in a radial direction (from the inside to the outside, perpendicular to the repeller shaft). The outer flange of the second insulator is attached to the outer shoulder of the first insulator, and the inner flange of the second insulator is pressed against a step on the repeller shaft. Thus, the second insulator and the step on the repeller shaft (or the step on the second insulator and the repeller shaft with a step) close the plasma path starting from the arc chamber. When a repeller shaft with two steps is used, the last step toward the end of the repeller shaft preferably closes the plasma path starting from the arc chamber. In a preferred embodiment, the first and second insulators are attached to each other by threading (e.g., screwing).

[0024] The first and second insulators are disposed within the repeller assembly adjacent to one another in the major longitudinal direction (x-direction / axial direction) along the repeller axis, with the radial directions (y and z-directions) perpendicular to the major longitudinal direction.

[0025] The first and second insulators are made from a high temperature ceramic material, preferably AI2O3, and electrically insulate the repeller from the arc chamber.

[0026] The abutment member is electrically connected to the repeller shaft and connected to the cathode support with a bias. Preferably, the abutment member is a cathode strap made of molybdenum (Mo), tungsten (W), or silver (Ag). The abutment member is disposed between the second insulator and the locking member.

[0027] The locking member is fixed onto the end of the repeller shaft so that the step of the repeller shaft having one step is pressed against the inner flange of the second insulator. When a repeller shaft configuration having two step portions is used, preferably the last step at the end of the repeller shaft is pressed against the inner flange of the second insulator. Thus, the repeller is held in a cantilevered manner within the arc chamber. The locking member may be made of molybdenum, tungsten, or stainless steel. In a preferred embodiment, the locking member is a lock nut.

[0028] In a preferred embodiment, the repeller assembly further includes a cup-shaped shield. The cup-shaped shield is inserted between the second insulator and the abutment member to cover at least the first and second insulators. Preferably, a circumferential recess is provided around the opening on the outer side of the arc chamber wall, and the cup-shaped shield extends into this recess. The cup-shaped shield can be made of different materials, such as graphite or a metallic material. Preferably, the cup-shaped shield is made of a metallic material such as aluminum, stainless steel, molybdenum, or tungsten. In another embodiment, the cup-shaped shield is made of an electrically insulating material, preferably a ceramic such as Al2O3, so that the cup-shaped shield can function as an insulator. If the cup-shaped shield is made of a metallic material, it can be easily cleaned from the deposited plasma and can be reused within the repeller assembly, thereby achieving cost savings.

[0029] In a preferred embodiment, the repeller assembly comprises a repeller, a cylindrical insert member, first and second insulators, an abutment member, and a locking member.

[0030] In a further preferred embodiment, the repeller assembly comprises a repeller, a cylindrical insert member, first and second insulators, a cup-shaped shielding portion, an abutting member, and a locking member.

[0031] In a preferred embodiment of the present invention, at least some parts of the repeller assembly, particularly the repeller, the cylindrical insert, and at least the first and second insulators, are geometrically configured to self-align when assembled along the main longitudinal direction (x-direction / axial direction) of the repeller axis. If the repeller is strictly cylindrical, e.g., having several cylindrical sections, the main longitudinal direction corresponds to the cylindrical axis. Therefore, these parts are axially positioned at the correct distance from each other and are correctly and securely positioned relative to each other in the radial direction (perpendicular to the axial direction). As mentioned above, these parts have corresponding geometrically configured shapes to achieve the self-aligning feature (this will be explained in more detail with reference to the drawings). In a preferred embodiment, this is also achieved, inter alia, by the sloping walls of the opening and the corresponding sloping walls of the flange of the cylindrical insert. Therefore, correct alignment between these parts is ensured when they are installed in the arc chamber of an ion implanter. Furthermore, the self-aligning feature eliminates the need for additional devices or measuring equipment to accurately position each part of the repeller assembly.

[0032] The present invention also relates to an ion implanter arc chamber including a repeller assembly as claimed in the claims. The repeller assembly is positioned within an opening in a wall of the arc chamber opposite the cathode assembly. For example, the wall of the arc chamber including the opening may be a rear wall of the arc chamber.

[0033] Using the claimed repeller assembly, an internal gap (or inner gap) is defined between the arc chamber and the repeller assembly, where the internal gap extends along the repeller body, then along the repeller shaft, and further between and terminates between the first and second insulators. Because the internal gap is formed along the repeller body, it is limited on opposite sides by adjacent portions of the repeller body, such as the arc chamber wall, end liner (or end liner), and / or tubular insert. Next, the internal gap extends along the repeller shaft, where it is limited on opposite sides by adjacent portions, such as the tubular insert and, for example, the first insulator. In a further step, the internal gap is limited by the arrangement of at least the first and second insulators and a circumferential recess on one side of the first insulator.

[0034] In the prior art, a repeller stem having a pair of radially protruding collars may be used. However, compared to the gap in this known configuration, the above-mentioned inner gap is very small. In the prior art, because the repeller had to be introduced into the opening in the end wall of the arc chamber from inside the arc chamber, the width of the gap between the repeller stem and each of the opening, the tubular shield, and the insulator ring depended on the size of the radially protruding collars of the repeller stem. The inner gap size according to the present invention is 2 mm or less, preferably in the range of 0.4 mm to 1.5 mm, and more preferably in the range of 0.5 mm to 1.0 mm. Therefore, by using the repeller assembly described in the claims, the size of the gap can be minimized, thereby reducing gas loss in the arc chamber during ion beam operation.

[0035] Furthermore, the inner gap forms an elongated, tortuous path, depending on the specific configuration of the different components of the repeller assembly, which, when viewed from inside the arc chamber, extends through the wall opening to the outside of the arc chamber and has at least five turns and at least one side branch. The side branch preferably extends between at least two insulators, more preferably within the first insulator. The width of the side branch is preferably less than 2 mm, preferably within the range of 0.4 mm to 1.5 mm, and more preferably within the range of 0.5 mm to 1.0 mm. Therefore, compared to paths disclosed in the prior art, the above-described plasma path is elongated due to the use of at least two insulators. When a two-step repeller shaft configuration is used, the inner gap forms an elongated, tortuous path with at least seven turns and at least one side branch. During ion beam operation of the arc chamber, this extended tortuous path can delay the buildup of a conductive plasma layer on the surfaces of the repeller assembly components, thereby extending the life of the repeller assembly during ion beam operation.

[0036] Furthermore, the claimed arc chamber including the repeller assembly defines an outer gap that extends between the outside of the arc chamber and the first insulator, then extends into and terminates within the first insulator. In this case, the outer gap forms a path having a single curve. The width of the outer gap is 2 mm or less, preferably within the range of 0.4 mm to 1.5 mm, and more preferably within the range of 0.5 mm to 1.0 mm. It is noted that none of the above-mentioned patent documents disclose or suggest an outer gap.

[0037] In a preferred embodiment of the present invention, the outer wall of the arc chamber exhibits a circumferential recess, and a cup-shaped shield is inserted between the second insulator and the abutment member, covering at least the first and second insulators and reaching at least partially into the recess outside the arc chamber. In this case, the outer gap further extends between the outside of the arc chamber and the cup-shaped shield, so that the outer gap forms an elongated, winding path with at least three bends. When viewed from the outside of the cup-shaped shield in a direction along the outside of the arc chamber, the outer gap then extends between the outside of the arc chamber and the first insulator, and then extends into the first insulator and terminates there. In this embodiment, it is clear that at least two bends are obtained by the outer wall of the arc chamber having a circumferential recess and the cup-shaped shield at least partially reaching this recess. By providing the cup-shaped shield, the outer gap further comprises a side branch, which extends between the first insulator and the cup-shaped shield, and then extends between the second insulator and the cup-shaped shield and terminates there. Therefore, in this preferred embodiment, a cup-shaped shield is inserted between the second insulator and the abutment member, covering at least the first and second insulators and reaching at least partially into a recess provided on the outside of the wall of the arc chamber, so that the outer gap forms a tortuous path having at least three bends and at least one side branch.

[0038] As described above, when the repeller and cylindrical insert are positioned inside the arc chamber, and at least the first and second insulators are positioned outside the arc chamber, and these components are assembled together through the opening in the wall of the arc chamber, the components of the repeller assembly self-align along the primary longitudinal direction of the repeller shaft. As described above, the primary longitudinal direction of the repeller shaft corresponds to the cylindrical axis of the repeller. Therefore, these components are positioned at the correct distance from each other axially and are correctly and securely positioned relative to each other radially (perpendicular to the axial direction). As described above, the distance between the repeller assembly and the cathode assembly is also automatically and accurately aligned (or registered). Compared to poorly / incorrectly aligned assemblies, the above-described repeller assembly is advantageous because it exhibits better performance and a longer service life. Misalignment of the repeller assembly can affect short circuits and / or cause the arc chamber to malfunction.

[0039] Additional features which are believed characteristic of the invention are set forth in the appended claims.

[0040] The present invention is described and illustrated herein as embodied in a repeller assembly mounted within the arc chamber of an ion implanter, and an arc chamber including the repeller assembly. However, it is not intended to limit the invention to the details shown, as various modifications and structural changes may be made to the invention within the scope and range of equivalents of the claims without departing from the spirit of the invention.

[0041] The structure and method of operation of the present invention, together with further objects and advantages, will be best understood from the following detailed description of specific embodiments, when read in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0042] [Figure 1] FIG. 1 is a perspective view of an arc chamber for an ion implanter in accordance with a preferred embodiment of the present invention. [Figure 2]FIG. 2 is an exploded perspective view of a repeller assembly according to a preferred embodiment of the present invention. [Figure 3A] FIG. 3A is a cross-sectional view of a repeller assembly mounted within the arc chamber illustrated in FIG. 1 in accordance with a preferred embodiment of the present invention, illustrating rotational symmetry about the repeller assembly. [Figure 3B] FIG. 3B is a cross-sectional view of a repeller assembly mounted within the arc chamber illustrated in FIG. 1 in accordance with a preferred embodiment of the present invention, illustrating rotational symmetry about the repeller assembly. [Figure 4A] FIG. 4A is a cross-sectional view of a repeller assembly mounted within the arc chamber illustrated in FIG. 1 in accordance with a further preferred embodiment of the present invention, illustrating rotational symmetry about the repeller assembly. [Figure 4B] FIG. 4B is a cross-sectional view of a repeller assembly mounted within the arc chamber illustrated in FIG. 1 in accordance with a further preferred embodiment of the present invention, illustrating rotational symmetry about the repeller assembly. DETAILED DESCRIPTION OF THE INVENTION

[0043] Referring now to the figures in detail, and initially to FIG. 1, an exterior view of an arc chamber 1 of an ion implanter is illustrated. The arc chamber 1 has an elongated box-shaped structure including a bottom, four side walls, and a top wall, with a liner (not visible in the figure) disposed underneath. In FIG. 1, the arc chamber 1 includes an outer wall, i.e., a rear wall 3, at one end thereof, which includes an opening 13 for mounting a repeller assembly. FIG. 1 illustrates the arc chamber 1 including a repeller assembly according to a preferred embodiment of the present invention. On the opposite side of the repeller assembly (in the front wall of the arc chamber) is a cathode assembly. In the embodiment illustrated in FIG. 1, the repeller of the claimed repeller assembly, a tubular insert, At least the first and second insulators are covered by a cup-shaped shield (or cup-shaped shield) 8 (therefore, they are not visible in FIG. 1). The cup-shaped shield 8 is fixed to a contact member 10 (e.g., a cathode strap) by a locking member 9 (e.g., a lock nut). As is clear from FIG. 1, the cup-shaped shield 8 and the contact member 10 are provided with holes (e.g., boreholes) so that the repeller shaft (or repeller shaft) can pass through these portions. Furthermore, in the same figure, the locking member 9 is screwed onto the end of the repeller shaft, making the end of the repeller shaft 2b visible.

[0044] FIG. 2 illustrates a portion of a preferred embodiment of the claimed repeller assembly. FIG. 2 illustrates a repeller 2 having a knob-shaped body 2a and a repeller shaft 2b, a cylindrical insert 5, a first insulator 6, a second insulator 7, a cup-shaped shield 8, an abutment member 10 (e.g., a cathode strap), and a locking member 9 (e.g., a lock nut). When the repeller assembly is assembled, the repeller shaft 2b passes through all the components, namely, the cylindrical insert, the first and second insulators, the cup-shaped shield, and the abutment member (both of which have holes in this area; see also FIG. 1), and is secured to the end using the locking member 9, in this example, a lock nut. As is clear from FIG. 2, in this embodiment, the cylindrical insert 5 and the first insulator 6 are threadedly attached to each other, as are the first insulator 6 and the second insulator 7. A cup-shaped shield 8 is positioned over the combined first and second insulators, completely covering them (outwardly). Furthermore, the specific configuration or design of the repeller shaft 2b, the tubular insert 5, the first (i.e., collar-shaped) insulator 6, and the second (i.e., cap-nut-shaped) insulator 7 allows for easy installation of the repeller 2 into the assembly. The repeller shaft 2b is inserted into a centrally located concentric hole in the second insulator 7 (i.e., the inner flange of the second insulator) before being secured. All components of the repeller assembly are assembled together along the main longitudinal direction of the repeller shaft, i.e., along the central axis of the repeller shaft. Figure 2 shows that the repeller, the tubular insert, and the first and second insulators are self-aligned along the main longitudinal direction of the repeller shaft. Therefore, proper alignment of these components of the repeller assembly is assured when installed within the opening in the wall of the arc chamber of the ion implanter. When threaded connections are used between the cylindrical insert and the first insulator and between the first insulator and the second insulator, the first and second insulators may be first assembled together and then installed as a unitary piece onto the cylindrical insert. Furthermore, when threaded connections are used between these components, the repeller assembly is self-aligning, so no additional tooling is required for precise positioning of the repeller assembly.Furthermore, as is apparent from FIG. 2, all parts of the repeller assembly are reversibly positioned, allowing for replacement of a single part of the repeller assembly, for example the repeller.

[0045] Referring to FIG. 3A, a cross-sectional view of one embodiment of the claimed repeller assembly is illustrated. FIG. 3A illustrates an arc chamber 1 including the claimed repeller assembly and a cup-shaped shield 8. The repeller assembly is mounted within the arc chamber 1 through an opening 13 in one end wall of the arc chamber 1, i.e., the rear wall 3 of the arc chamber. The repeller assembly is located at the other end (i.e., the front wall) of the arc chamber, opposite the cathode assembly (not shown). The repeller assembly is comprised of a repeller 2, a cylindrical insert 5, a first insulator 6, a second insulator 7, an abutment member 10, and a locking member 9. FIG. 3A also illustrates a cup-shaped shield 8, which is positioned between the second insulator 7 and the abutment member 10 and covers the first and second insulators. Because FIG. 3A is rotationally symmetrical with respect to the repeller assembly, reference numerals for describing the components of the repeller assembly are assigned only once. This does not apply to components of the arc chamber (e.g., the top wall, liner, or end liners). As mentioned above, the rear wall 3 has an opening 13. The repeller 2 and cylindrical insert 5 must be inserted into the repeller assembly from the inside 1a of the arc chamber. The first and second insulators, the abutment member 10, the locking member 9, and the cup-shaped shield 8 are located outside the arc chamber. A circumferential recess 14 around the opening 13 in the rear wall 3 is shown on the outside 3b of the rear wall 3. Also shown in FIG. 3A are the top wall 12 of the arc chamber, the inside of the arc chamber, the liner 11 below the top wall, and the end liner 4. The repeller 2 has an enlarged, nodular body 2a inside the arc chamber and an integral shaft portion (repeller shaft) 2b, which extends through the opening 13 in the rear wall 3 and faces the outside of the arc chamber. The repeller shaft 2b is integral with the center of the nodular body having a predetermined initial diameter. The repeller shaft 2b has a step that reduces or narrows the initial diameter of the shaft at the beginning of the shaft (starting from the nodular body) toward the end of the shaft, so that the diameter of the repeller shaft narrows behind the step.The end liner 4 is mounted using a spacer ring 4a between the inner surface 3a of the rear wall 3 of the arc chamber and the nodular structure 2a, preventing flaking during operation, which could cause a short circuit. This configuration also extends the inner clearance, thereby further extending the coating path. A cylindrical insert 5 is mounted concentrically within the rear wall opening, around the repeller axis. The cylindrical insert 5 is a flanged bushing with one end facing the interior 1A of the arc chamber 1 and a uniform-diameter bushing or bushing at the other end. Because the opening in the rear wall 3 tapers axially from the interior 3a to the exterior 3b of the rear wall 3, the flange of the cylindrical insert is axially tapered and has a larger diameter than the bushing. Thus, the cylindrical insert abuts the rear wall 3 of the arc chamber 1. The bushing of the cylindrical insert is provided with a means for retaining the first insulator 6. The first insulator 6 has a collar shape including a radial inner shoulder 6b and an outer shoulder 6a. The first insulator is attached to the cylindrical insert 5 so that the inner shoulder 6b of the first insulator is pressed against the rear wall 3 of the arc chamber. Therefore, the first insulator abuts against the rear wall of the arc chamber. Furthermore, the first insulator has a circumferential recess 15 at one end of the first insulator, opposite the outer and inner shoulders. The second insulator 7 is attached to the first insulator and has a cap-nut-like structure. As illustrated in FIG. 3A , the outer flange 7a of the second insulator is attached to the first insulator. Furthermore, the inner flange 7b of the second insulator abuts against a stepped portion of the repeller shaft. As described above, the cup-shaped shielding portion 8 covers the first and second insulators and extends into the recess 14 provided on the outside of the rear wall 3b. The abutment member 10 is electrically connected to the end of the repeller shaft and is arranged to be attached to the cup-shaped shield and repeller assembly using a fixing member 9. Therefore, the inner flange 7b of the second insulator is pressed against the stepped portion of the repeller shaft 2b, and the flange 7a of the second insulator is pressed against the outer shoulder 6a of the first insulator.

[0046] The repeller must be installed from the inside 1a of the arc chamber 1 through the opening 13 in the rear wall 3 to the rest of the assembly. Therefore, the repeller shaft is obviously designed to allow for easy installation and replacement of the repeller. FIG. 3A illustrates an embodiment in which the bushing of the cylindrical insert 5 is threaded onto the first insulator 6. The first insulator 6 is threaded onto the second insulator 7, and a locking member 9 is threaded onto the end of the repeller shaft 2b. In this preferred embodiment, the components of the repeller assembly self-align along the main longitudinal axis of the repeller shaft 2b when assembled together. In FIG. 3A, the main longitudinal axis is illustrated as the x-axis (axial direction). The components of the repeller assembly are geometrically configured to allow for precise self-alignment of the components at fixed positions in the x-, y-, and z-directions. Thus, the claimed repeller assembly can be easily installed within the arc chamber without the need for additional equipment or measuring devices that are typically required to properly position each component of the repeller assembly within the opening in the wall of the arc chamber.

[0047] FIG. 3B, like FIG. 3A, shows the repeller assembly installed in the arc chamber, highlighting the inner gap and outer gap defined when the repeller assembly is inserted into the arc chamber. The inner gap extends along the body of the repeller (bounded on opposite sides by the end liner and the tubular insert), then along the axis of the repeller (bounded on opposite sides by the tubular insert and the first insulator), and then between and terminates at the first and second insulators. In this embodiment, the first insulator has a circumferential recess, which acts as a side branch with respect to the inner gap. The black lines illustrate the flow of plasma / gas from inside the arc chamber to outside. As shown, gas flows along the repeller, through an opening in the rear wall of the arc chamber, and then along the tubular insert, the first insulator, and the second insulator. The installation of the cylindrical insert and the specific configuration of the two insulators provide an extended, tortuous inner gap for the plasma flow. This gap has five bends (or turns) and one side branch (as viewed from the inside of the arc chamber). This extends the time until the entire gap is covered with plasma. This extends the time until the entire gap is covered with plasma. This results in a longer arc chamber life. Figure 3B also illustrates the outer gap. Without the cup-shaped shield, the outer gap extends between the outside of the arc chamber rear wall 3b and the first insulator, terminating there. In this regard, Figure 3B illustrates a preferred embodiment of a repeller assembly with a cup-shaped shield. Therefore, the outer gap extends further outside the cup-shaped shield 8a, between the cup-shaped shield and the rear wall of the arc chamber, and between the second insulator and the cup-shaped shield, terminating there. The exterior of the arc chamber rear wall provides a circumferential recess into which the cup-shaped shield extends at least partially. This configuration provides two additional curvatures in the outer gap compared to the embodiment without a recess in the rear wall. In Figure 3B, an extended, serpentine outer gap is provided for the plasma flow.This gap has four curved sections and one side branch. The figure also illustrates that the width of the inner gap and the outer gap is 2 mm or less over their entire length.

[0048] FIG. 4A illustrates a cross-sectional view of another embodiment of the claimed repeller assembly. The main parts of this figure correspond to the repeller assembly illustrated in FIG. 3A. However, the repeller shaft of the repeller has two stepped portions. Therefore, the description of FIG. 3A can be mainly referred to here, and only the differences in the arrangement of the repeller assembly compared to the repeller assembly illustrated in FIG. 3A are emphasized. In this repeller assembly, the two stepped portions of the repeller shaft 2b narrow the initial diameter of the shaft from the beginning of the shaft (starting from the knob) to the end of the shaft, and the diameter of the repeller shaft is reduced at each stepped portion. In this embodiment, the second step at the end of the repeller shaft is pressed against the inner flange 7b of the second insulator, and the first step of the repeller shaft (located adjacent the nodular body) is located within the flange (or flange) of the tubular insert member 5 when the entire arrangement is fixed onto the repeller shaft.

[0049] FIG. 4B, like FIG. 4A, shows the repeller assembly installed in the arc chamber, but particularly emphasizes the inner and outer gaps defined when the repeller assembly is inserted into the arc chamber. While the paths of the inner and outer gaps are explained in FIG. 3B, the explanation for FIG. 3B is equally applicable to FIG. 4B. The black lines indicate the plasma / gas flow from the inside of the arc chamber to the outside. The cylindrical insert, two insulators, and two stepped shaft sections provide an extended, serpentine inner gap for the plasma flow, with seven bends and one side branch (as viewed from inside the arc chamber). The figure also illustrates that the width of the inner and outer gaps is 2 mm or less throughout their entire length.

[0050] Thus, the claimed invention provides a repeller assembly which, when installed in the arc chamber of an ion implanter, can improve the life performance of the ion implanter during ion beam operation. Thus, the claimed invention can reduce the frequency of maintenance shutdowns in the arc chamber.

[0051] The self-aligning configuration of these components allows for accurate placement of the repeller assembly without the use of additional equipment or measuring devices.

[0052] Additionally, each single piece of the repeller assembly allows for easier manufacturing and / or replacement (eg, of the repeller).

[0053] A summary list of reference numbers and corresponding structures used in the above description of the present invention is provided below. [Explanation of symbols]

[0054] 1. Arc chamber 1a Inside the arc chamber 2 Repeller 2a Repeller knob-like protrusion 2b Repeller integrated shaft part 3. Rear wall of the arc chamber 3a Inside the posterior wall 3b Outside of the posterior wall 4 End liner (or end liner) 4a Spacer ring 5. Cylindrical insert (or tubular insert) 6 First Insulator 6a Inner shoulder (or inner shoulder) of first insulator 6b Outer shoulder (or outer shoulder) of the first insulator 7 Second Insulator 7a Outer collar (or outer flange) of second insulator 7b Inner collar (or inner flange) of second insulator 8 Cup-shaped shielding section (or cup-shaped shield) 8a Outside of the cup-shaped shielding part 9. Locking member, preferably a lock nut 10 Abutment member (or contact member), preferably a strap 11 Liner 12 Arc chamber top wall 13 Opening in rear wall of arc chamber 14 Outer recess of rear wall 15 Recess of first insulator

Claims

1. A repeller assembly for installation within an arc chamber of an ion implanter, the assembly including a repeller, a cylindrical insert member, a first insulator, a second insulator, an abutment member, and a locking member; the repeller has a nodular body disposed inside the arc chamber on the opposite side of the arc chamber from the cathode assembly, and a repeller shaft integral with the nodular body, the repeller shaft being disposed so as to extend outside the arc chamber through an opening in a wall of the arc chamber, and the repeller shaft having at least one step portion narrowing the repeller shaft; The cylindrical insert member is attached concentrically to the repeller shaft, the first insulator has an inner shoulder and a collar shape, and is attached to the cylindrical insert so that the inner shoulder of the first insulator is pressed against the outside of the wall of the arc chamber; the second insulator has a cap-nut shape and includes an inner flange and an outer flange, the second insulator is attached to the first insulator via the outer flange; The contact member is electrically connected to the repeller shaft, and the locking member is fixed to the repeller shaft so that at least one stepped portion of the repeller shaft is pressed against the inner flange of the second insulator. Repeller assembly.

2. The repeller assembly of claim 1 , wherein the abutment member is disposed between the second insulator and the locking member.

3. The repeller assembly according to claim 1 , further comprising a cup-shaped shielding portion, the cup-shaped shielding portion being inserted between the second insulator and the abutment member and covering at least the first and second insulators.

4. The repeller assembly of claim 1 , wherein the abutment member is a cathode strap.

5. The repeller assembly of claim 1 , wherein the locking member is a lock nut.

6. 2. The repeller assembly of claim 1, wherein the repeller, the cylindrical insert, and the first and second insulators of the repeller assembly are geometrically configured such that when assembled together, the components self-align along a major longitudinal axis of the repeller shaft.

7. The repeller assembly of claim 1 , wherein the first insulator and the tubular insert are attached to one another by a threaded connection.

8. The repeller assembly of claim 1 , wherein the first insulator and the second insulator are attached to one another by a threaded connection.

9. 2. The repeller assembly of claim 1, wherein the repeller shaft has exactly one of the at least one stepped portion, the stepped portion narrowing the repeller shaft toward an end of the repeller shaft.

10. 2. The repeller assembly of claim 1, wherein the at least one step narrowing the repeller shaft is one of at least two steps narrowing the repeller shaft toward an end of the repeller shaft.

11. The repeller assembly of claim 1 , wherein the tubular insert is made from an electrically insulating material.

12. The repeller assembly of claim 3 , wherein the cup-shaped shield is made from an electrically insulating material.

13. 1. An arc chamber of an ion implanter comprising: a cathode assembly; a wall having an opening formed therein; a repeller assembly according to any one of claims 1 to 12; the repeller assembly is disposed within the opening in the wall of the arc chamber opposite the cathode assembly to define an inner gap, the inner gap extending along the nodular body of the repeller, then along the axial portion of the repeller, then extending between and terminating in the first insulator and the second insulator, and the width of the inner gap is 2 mm or less.

14. 14. The arc chamber of claim 13, wherein the inner gap forms a tortuous path including at least five bends and at least one side branch.

15. 14. The arc chamber of claim 13, wherein the repeller, the cylindrical insert, and the first and second insulators of the repeller assembly are geometrically configured such that when the repeller and the cylindrical insert are positioned inside the arc chamber and the first and second insulators are positioned outside the arc chamber and the components are assembled together through the opening in the wall of the arc chamber, the components are self-aligned along a major longitudinal direction of the repeller axis.

16. 14. The arc chamber of claim 13, wherein an outer gap is defined outside the arc chamber, the outer gap extending between the outside of the arc chamber and the first insulator, and then extending into and terminating in the first insulator, and wherein a width of the outer gap measures 2 mm or less.

17. 17. The arc chamber of claim 16, further comprising a cup-shaped shield, wherein the outer gap further extends between an exterior of the arc chamber and the cup-shaped shield, the outer gap forming a serpentine path including at least three bends.

18. 18. The arc chamber of claim 17, wherein the outer gap further includes a side branch, the side branch extending between the first insulator and the cup-shaped shield and then extending between and terminating in the second insulator and the cup-shaped shield.

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