TW201822240A - Ion source liner having a lip for ion implantation systems - Google Patents

Abstract

An ion source has an arc chamber having a body defining and interior region. A liner defined an exposure surface of the interior region that is exposed to a plasma generated within the arc chamber. An electrode has a shaft with a first diameter that passes through the body and the liner. The electrode is electrically isolated from the body where the liner is a plate having a first surface with an optional recess having a second surface. A hole is defined through the recess for the shaft to pass through. The hole has a second diameter that is larger than the first diameter, and an annular gap exists between the plate and the shaft. The plate has a lip extending from the second surface toward the first surface that surrounds the hole within the recess and generally prevents particulate contaminants from entering the annular gap.

Description

Ion source lining with lip for ion implantation system

The present invention is generally directed to ion implantation systems, and more particularly to a liner for an ion source arc chamber.

Among the fabrication of semiconductor devices, they use ion implantation to incorporate impurities into the semiconductor. Typically, it uses an ion implantation system that uses ions from an ion beam to dope a workpiece such as a semiconductor wafer to produce an n-type or p-type material doping, or in an integrated circuit. A passivation layer is formed during the period. Such beam processing is often used to selectively implant impurities of a particular dopant material at a controlled energy level at a controlled concentration to produce a semiconductor material during production of an integrated circuit. . When used to dope a semiconductor wafer, the ion implantation system injects a selected ion species into the workpiece to produce the desired exogenous material. Bulk ions generated from a source material such as germanium, arsenic, or phosphorous, for example, resulting in an "n-type" exogenous material wafer, while a "p-type" exogenous material wafer is typically derived from, for example, boron. Ions generated by the source material such as gallium or indium.

A typical ion implanter includes an ion source, an ion extraction device, a mass analysis device, a beam transport device, and a wafer processing device. The ion source produces ions of the desired atom or molecular doping species. This isometric The subsystem is extracted from the source by an extraction system. Typically, the extraction system is a set of electrodes that excite and direct the flow of ions from the source to form an ion beam. The desired ions are separated from the ion beam by a mass spectrometer, typically a magnetic bipolar, performing mass dispersion or separation of the extracted ion beam. A beam delivery device, typically a vacuum system comprising a series of focusing devices, transmits an ion beam to a wafer processing device while maintaining the desired properties of the ion beam. Finally, through a wafer control system, the semiconductor wafer is fed into and out of the wafer processing apparatus, wherein the wafer control system can include one or more robotic arms for placing a wafer to be processed on the ion beam. The front side and the processed wafer are removed from the ion implanter.

Batch type ion implanters are well known and typically comprise a rotating disk support for moving a plurality of germanium wafers through an ion beam. When the support rotates the wafer through the ion beam, the ion beam strikes the surface of the wafer. Tandem ion implanters are also conventional devices that process one wafer at a time. The wafer is supported in a cassette, one at a time and placed in a wafer support. The wafer is then adjusted to an implant orientation such that the ion beam strikes a single wafer. These tandem implanters use beam shaping electronics to deflect the beam from its original trajectory and are typically used in conjunction with coordinate wafer support movement to selectively dope or process the entire wafer surface. When the wafer is processed by an ion implantation system, it is transferred between a dedicated processing chamber and a wafer input/output station. It is customary to use a robot to feed wafers into and out of the processing chamber.

The present disclosure therefore proposes a system and apparatus for increasing the lifetime of an ion source. Correspondingly, a simplified summary of the disclosure is presented below to provide a basic understanding of some features of the invention. This summary is not an extensive discussion of the invention. It is not intended to identify key or critical elements of the invention or the scope of the invention. Its purpose is to present in a simplified form Some of the concepts of the present invention are presented as a prelude to a more detailed description that will be presented later.

In accordance with one feature of the present disclosure, an ion source is provided, such as an ion source for an ion implantation system or various other processing systems. For example, the ion source includes an arc chamber having a body defining an interior region of the arc chamber. For example, one or more linings are operatively coupled to the body of the arc chamber, wherein the one or more linings generally define an exposed surface of the interior of the arc chamber region. For example, the exposed surface is exposed to, and at least partially arrested, a plasma generated within the arc chamber interior region.

In one example, another electrode is provided, such as a repeller, wherein the electrode includes a shaft portion having a first diameter. The shaft portion passes through one of the body and the one or more linings, wherein the electrode is electrically isolated from the body. In one example, one of the one or more liners includes a plate having a first surface, the first surface having a depression having a second surface defined in the depression. A hole is defined through the recess, wherein the hole is configured to pass through the shaft through the hole. For example, the hole has a second diameter greater than the first diameter, defining an annular gap therebetween between the plate and the shaft portion. Additionally, the plate includes a lip extending from the second surface toward the first surface, wherein the lip surrounds the hole in the recess and generally prevents particulate contaminants from entering the gap. In another example, the aforementioned depression does not exist and the lip extends outwardly from the first surface.

According to an example, the second surface is recessed from the first surface by a first distance, wherein the lip extends a second distance from the second surface toward the first surface. One or more of the first surface and the second surface may be generally planar. In a special non-limiting In the example, the first distance is approximately twice the second distance. In another example, the lip includes a third surface adjacent a perimeter of the aperture. The third surface can also be generally planar, but can be envisioned in a variety of other configurations, such as circular or faceted surfaces. In one example, the recesses are generally U-shaped when viewed along one of the axes of the aperture.

In yet another example, the slab described above defines a bottom surface of the interior of the arc chamber, wherein the lip generally prevents gravity from entering particulate matter.

In yet another example, the lip has a third diameter associated therewith. The electrode described above may comprise a repeller having a head exposed to plasma generated within the arc chamber interior region, wherein the head has a fourth diameter. In an example, the fourth diameter is greater than the third diameter.

According to various other examples, an ion source processing chamber is provided having an electrode including a shaft portion and a head portion. An inner liner is further provided to the ion source processing chamber, wherein the inner liner has a hole therethrough, and wherein the electrode passes through the hole and defines an annular gap between the shaft portion and the hole . For example, the liner further includes a recess having a lip extending from the recess to generally surround the aperture and generally prevent particulate contaminants from passing through the aperture.

In another example, the electrode includes a repeller device, wherein the repeller device includes a repeller electrode operatively coupled to the shaft portion. One of the diameters of the repeller electrode is, for example, larger than one of the diameters of the hole, and wherein a diameter of the shaft portion is smaller than a diameter of the hole. In another example, a diameter of the lip is between the diameter of the repeller electrode and the diameter of the hole.

Accordingly, the following description and the annexed drawings are intended to illustrate the specific exemplary features and embodiments of the invention. These are merely representative of some of the many ways in which the principles of the invention may be employed.

100‧‧‧Ion source

102‧‧‧ surface

103‧‧‧Internal parts

104‧‧‧ cathode

106‧‧‧ rapper

108‧‧‧Arc chamber

110‧‧‧ side wall

112‧‧‧ lining

114‧‧‧Contaminant

115‧‧‧Replaceable components

116‧‧‧ Subject

118‧‧‧ gap

119‧‧‧ partially enlarged view

120‧‧‧Bottom lining

122‧‧‧ dent

124‧‧‧ hole

126‧‧‧Axis

200‧‧‧Ion source

202‧‧‧Arc chamber

204‧‧‧Bottom lining

206‧‧‧ annular gap

208‧‧‧electrode

210‧‧‧ Subject

212‧‧‧Internal area

214‧‧‧ lining

216‧‧‧ exposed surface

218‧‧‧Axis

220‧‧‧first diameter

222‧‧‧ tablet

224‧‧‧ first surface

226‧‧‧ dent

227‧‧‧ bottom view

228‧‧‧ second surface

229‧‧‧ profile

230‧‧‧ hole

232‧‧‧second diameter

234‧‧‧Lip

236‧‧‧First distance

238‧‧‧Second distance

240‧‧‧ third surface

Around 242‧‧

244‧‧‧ axis

246‧‧‧ third diameter

248‧‧‧ repeller

250‧‧‧ head

252‧‧‧fourth diameter

1 is a perspective view of an exemplary ion source and arc chamber with a liner.

Figure 2 is a partial enlarged view of Figure 1 showing an arc chamber having an inner liner but without a raised lip.

3 is a perspective view of an exemplary ion source liner.

4 illustrates a perspective view of an ion source and an arc chamber having an inner liner with a raised lip in accordance with some examples of the present disclosure.

Figure 5 is a partial enlarged view of Figure 4 showing an arc chamber having a liner having a raised lip in accordance with some examples of the present disclosure.

6 illustrates a plan view of an arc chamber of an exemplary ion source having an inner liner having a raised lip in accordance with some examples of the present disclosure.

7 is a perspective view of an exemplary ion source liner having a raised lip in accordance with some examples of the present disclosure.

8 is a bottom plan view of an exemplary ion source liner in accordance with some examples of the present disclosure.

9 is a cross-sectional view of FIG. 8 showing an ion source liner having a raised lip in accordance with some examples of the present disclosure.

The present invention generally relates to a lining by having an ion source lining A system, apparatus, and method for reducing the maintenance of an ion source and increasing its productivity. Based on the above, the present invention will be described with reference to the drawings, wherein like reference numerals are used throughout the drawings. It should be understood that the description of such features is merely illustrative and should not be construed as limiting. In the following description, numerous specific details are set forth to provide a It will be apparent to those skilled in the art, however, that the invention may be practiced without departing from the specific details.

An ion source (often referred to as an arc ion source) produces an ion beam for use in an implanter that can include heating a filament cathode to generate ions that are shaped into a suitable ion beam for wafer processing. For example, U.S. Patent No. 5,497,006 to Sferlazzo et al. discloses an ion source having a cathode supported by a susceptor disposed relative to a gas enclosure for ejecting ionized electrons to the gas enclosure. The cathode of the above-mentioned Sferlazzo et al., a tubular electrically conductive body, has an end cap that extends partially into the gas enclosure. A filament is supported within the tubular body and emits electrons that are bombarded by electrons that heat the end cap to inject ionized electrons into the gas enclosure in the form of thermionic ions.

An extraction electrode is disclosed, for example, in U.S. Patent No. 6,501,078, issued to Ryding et al., for example, substantially in conjunction with an ion source for extracting an ion beam therefrom, which is formed in a closed chamber. The ions are extracted through an exit aperture located on the front side of the ion source. The front side of the ion source forms a first apertured source electrode at the potential of the ion source. The extraction electrodes typically include an aperture suppression electrode and an aperture ground electrode aligned with the first aperture source electrode (sometimes referred to as an extraction electrode) to allow the ion beam to exit from the ion source among them. In a preferred embodiment, each opening has an elongated slot configuration. Typically, ceramic insulators are loaded with suppression and The two electrodes are electrically insulated between the ground electrodes. The ground electrode has a limitation on the area where the electric field between the ground electrode and the ion source propagates into the lower end of the ground electrode. The suppression electrode is biased by a voltage supply that is at a negative potential relative to the ground and operates to prevent electrons in the ion beam located at the downstream end of the ground electrode from being drawn into the extraction region and into the ion source.

An exemplary system for electrode voltage modulation in an ion source extraction electrode apparatus is described in U.S. Patent No. 9,006,690, the entire disclosure of which is incorporated herein by reference. U.S. Patent Application Publication No. 2011/0240889, the entire disclosure of which is incorporated herein by reference.

The present disclosure proposes an apparatus that is configured to increase the utilization of an ion source processing chamber in an ion implanter and reduce its downtime. However, it should be understood that the apparatus of the present disclosure may also be implemented in other semiconductor processing equipment, such as CVD, PVD, MOCVD, etching equipment, and various other semiconductor processing equipment, and all such embodiments are considered to be falling Within the scope of this disclosure. The apparatus of the present disclosure advantageously increases the length of use of the source processing chamber between preventive maintenance cycles, and thus increases the overall productivity and longevity of the system.

An ion source (also known as an ion source processing chamber) can be used in an ion implantation system, and refractory metals (tungsten (W), molybdenum (Mo), tantalum (Ta), etc.) can be used with Graphite is constructed to provide suitable high temperature performance, which are generally accepted by semiconductor wafer producers. An ion source gas is used within the ion source processing chamber, wherein the ion source gas is either electrically conductive or not. However, once the ion source gas bursts or is ejected by fragmentation of the device, by-products of the ionized gas may be quite corrosive.

Examples of a boron trifluoride-based ion source gas _{(boron tri-fluoride; BF 3} ), which can be used as a raw material gas to produce boron in an ion implantation system 11 or BF ₂ ion beam. During the ionization of the BF ₃ molecule, it produces three free fluorine groups. A refractory metal such as molybdenum and tungsten can be used to construct or line the ion arc source processing chamber to maintain its structural integrity at an operating temperature of about 700 °C. However, refractory fluorides are volatile and have very high vapor pressures even at room temperature. The fluorine-based one formed in the ion source processing chamber attacks metal tungsten (or molybdenum, or graphite) and forms tungsten hexafluoride (WF ₆ ) (or fluoride of molybdenum or carbon): WF ₆ → W ⁺ +6 F ^- (1) or (MoF ₆ → Mo ⁺ +6 F ) (2)

The tungsten hexafluoride will substantially decompose above the hot surface. For example, in an ion source 100 depicted in FIG. 1, tungsten hexafluoride or other build-up material can be decomposed on surface 102 of various internal components 103 of the ion source, such as an arc chamber associated with an ion source. A cathode 104 of 108, a repeller 106 and a surface of an arc slit optic (not shown). This is referred to as a halogen cycle, as shown in equation (1), but the resulting material may also precipitate and/or condense back to the side of the arc chamber 108 in the form of a contaminant 114 (eg, solid particulate contaminants). Wall 110 or liner 112, and above the arc slit. For example, the liner 112 includes a replaceable member 115 that is operatively coupled to a body 116 of the arc chamber 108, wherein the liners are comprised of graphite or various other materials. For example, the replaceable member 115 described above provides a wear surface that can be easily replaced after the arc chamber 108 has been in operation for a period of time.

Another source of contaminant 114 deposited onto internal component 103 is produced from cathode 104 (e.g., a cathode composed of tungsten or tantalum) when the cathode is indirectly heated, wherein the indirectly heated cathode is used to initiate and maintain Plasma source plasma (eg, a thermionic electron emission). For example In other words, the indirect heating cathode 104 and the repeller 106 (eg, an anti-cathode) are at a negative potential relative to the body 116 of the arc chamber 108, and both the cathode and the repeller are permeable. The ionized gas is sputtered. For example, the repeller 106 can be constructed from tungsten, molybdenum, or graphite. Yet another source of contaminant 114 deposited over internal component 103 of arc chamber 108 is a dopant material (not shown) itself. As time progresses, the deposited film of these contaminants 114 may become stressed and then delaminated, thereby shortening the life of the ion source 100.

Surface conditions play an important role between a substrate and the film deposited thereon. For example, the London dispersion force describes the interaction between transient bipolar or multipoles associated with different parts of matter, explaining a major part of the attractive van der Waals force. . These results have a significant impact in exploring a better understanding of the atomic and molecular adsorption properties of different metal substrates. A multi-order model that integrates first-principles calculations and kinetic rate equation analysis shows a significant reduction in the temperature of proliferation from 1000 °C to 250-300 °C.

Since the formation of strong atomic bonds in the interface region is unlikely to occur, the difference in thermal expansion coefficient between the substrate (eg, cathode 104, liner 112, and/or repeller 106) and deposited contaminant 114, high power and Thermal cycling during low-power ion beam transitions, as well as decomposition of implanted materials located within the boundaries of the uneven plasma, can cause premature failure. The residual stress in these deposits consists of two types: one is from the enthalpy during the film growth; the other is due to the mismatch between the thermal expansion coefficients of the substrate and the deposited film.

As the film thickness of the contaminant 114 increases, the stretching and/or compressive stress will reach a threshold level at the interface with the substrate, such that peeling or delamination may occur within the ion source 100. When such delamination of the pollutant 114 occurs, the current delaminated pollutant may fall into the pass. A gap 118 between the repeller 106 and the liner 112 defined by the body 116 of the arc chamber 108 is depicted as a partial enlarged view 119 of FIG. 2, wherein the gap removes the push applied by an electrical bias Electrical coupling between the repeller and the body of the arc chamber.

3 illustrates a bottom liner 120 that is provided in the ion source 100 of FIGS. 1 and 2, wherein the bottom liner includes a recess 122 and a hole 124, and wherein the hole is configured To accept one of the shaft portions 126 of the repeller 106 in FIGS. 1 and 2. In this regard, the aforementioned indispensable gap 118 is provided between the shaft portion and the bottom liner 120. However, it should be noted that the recess 122 is generally planar to accommodate the repeller 106 in the bottom liner 120 of FIG. As shown in FIGS. 1 and 2, one of the heads 128 of the repeller 106 covers a line of sight leading to a gap 118 between the shaft portion 126 of the repeller and the body 116 of the arc chamber 108. However, the fine particulate contaminants 114 may still fall into the recess 122 and subsequently enter the gap 118 between the shaft portion 126 and the bottom liner 120. The contaminants 114 are electrically conductive and disposed in the gap 118 to electrically short the biased repeller 106 to the body 116 of the arc chamber 108, thereby causing a non-scheduled scheduled maintenance and/or The plasma is unstable, which in turn affects the quality of the ion beam formed therefrom.

Based on the above, Figures 4 and 5 illustrate an ion source 200 of the present disclosure having structures and components that are somewhat similar to the ion source 100 of Figures 1 and 2; however, the ion source 200 of Figures 4 and 5 An exemplary arc chamber 202 is included having a bottom liner 204 that is configured to substantially prevent contaminants from entering an annular gap between an electrode 208 and a bottom liner of the arc chamber. 206, thereby substantially avoiding premature failure of the ion source.

According to an exemplary feature, a body 210 of the arc chamber 202 generally defines an interior region 212 of the arc chamber. Additionally, one or more liners 214 are operatively coupled to the arc The body 210 of the chamber 202, wherein the one or more linings generally define an exposed surface 216 of the arc chamber interior region 212. For example, the one or more liners 214 include at least the bottom liner 204. It should be noted that although the term "bottom" is currently used to refer to the bottom liner 204, the bottom liner does not have to be disposed at a lowermost position of the arc chamber 202. For example, the exposed surface 216 is exposed to, and at least partially constrained by, a set of plasma generated within the interior region 212 of the arc chamber 202 (not shown).

According to an example, the electrode 208 includes a shaft portion 218 having a first diameter 220 depicted in FIG. 6, wherein the shaft portion passes through the body 210 and the bottom liner 204. Electrode 208 is electrically isolated from body 210, as will be discussed below, wherein bottom liner 204 includes a flat plate 222 having a first surface 224 defining a recess 226 therein. For example, the recess 226 has a second surface 228 defined therein, and another hole 230 is defined through the recess, as shown in more detail in FIGS. 6 and 8. 8 illustrates a bottom view 227 of the bottom liner 204, and FIG. 9 illustrates a cross-section 229 of the bottom liner, for example, wherein the holes 230 are configured to pass through the holes through the electrodes 208 of FIGS. 4-5. Shaft portion 218. The bore 230 has a second diameter 232 that is greater than the first diameter 220 of the shaft portion 218 of FIG. Accordingly, the annular gap 206 is defined between the plate 222 and the shaft portion 218 to electrically insulate the shaft portion from the bottom liner 204.

In accordance with the present disclosure, the plate 222 further includes a lip 234 extending from the second surface 228 toward the first surface 224. In this regard, the lip 234 generally surrounds the aperture 230 in the recess 226 in the bottom liner 204 while leaving an annular gap 204 between the plate 222 and the shaft portion 218 of the electrode 208 for intervening Electrically isolated. Thus, the lip 234 generally prevents particulate contaminants from entering the annular gap 206 by gravity, thereby preventing the electrode 208 and the main body of the arc chamber 202. An electrical short between the body 210 and the bottom liner 204.

According to an example, as depicted in FIG. 9, the second surface 228 is recessed from the first surface 224 by a first distance 236. In the present example, the lip 234 extends a second distance 238 from the second surface 228 toward the first surface 224. In the present example, the first distance 236 is approximately twice the second distance 238, but such distances may vary with the design of the electrode 208 of Figures 5-6 or other design criteria. As shown in FIG. 9, one or more of the first surface 224 and the second surface 228 may be generally planar. However, although not shown in the drawings, one or more of the first surface 224 and the second surface 228 may be inclined or have a curved appearance, and such appearances should all be considered to fall within the present disclosure. Within the scope.

According to another example, the lip 234 described above includes a third surface 240 adjacent a perimeter 242 of the aperture 230 in FIG. In one example, the third surface 240 is generally planar, as shown in FIG. Moreover, according to another example, the recess 226 described above is generally U-shaped when viewed along one of the axes 244 of the aperture 230, as depicted in FIG.

According to yet another example, the lip 234 described above has a third diameter 246 associated therewith, as depicted in FIG. For example, electrode 208 of FIG. 6 can include a repeller 248 (sometimes referred to as a counter cathode) located above the bottom of arc chamber 202. For example, the repeller 248 has a head 250 that is exposed to plasma (not shown) generated within the interior region 212 of the arc chamber 202, wherein the head has a fourth diameter 252, and wherein The fourth diameter is greater than the third diameter 246 of the lip 234 of FIG.

As suggested by the examples in Figures 4-6, the plate 222 defines a bottom surface 246 in the interior region 212 of the arc chamber 202, wherein the lip 234 generally prevents particulate contaminants 248 from falling by gravity Annular gap 206. Therefore, delamination from the arc chamber 202 The particulate contaminants 248 will generally fall above the bottom surface 246 due to gravity.

Although the repeller 106 can obscure the line of sight leading to the gap 118 between the electrode of Figure 2 and the body 116 of the arc chamber 108, the minute particulate matter 114 will eventually enter the gap. However, the lip 234 in the arc chamber 202 of FIGS. 4-6 substantially prevents particulate contaminants 248 from entering the gap 206. In addition, the lip 234 of the present disclosure provides a reduction in process gas leakage through the gap 206 because the raised lip structure reduces the conductivity. This highly volatile and typically electrically conductive gas will coat any insulator used in the arc chamber configuration and shorten its life.

In another example, although not shown in the drawings, the bottom liner may be a flat plate having a raised lip extending from the first surface around the repeller shaft and may have the same as shown Similar or different appearance. Based on the above, the lip or raised portion on the bottom lining of the arc chamber will prevent particles of fine matter scattered from the arc chamber from entering the gap between the repeller shaft portion and the arc chamber body. The scattering of such conductive material can cause a biased repeller to short circuit to the arc chamber body, resulting in a non-scheduled predetermined maintenance and/or plasma instability, which in turn affects the quality of the ion beam.

Although the present invention has been shown and described with respect to the preferred embodiments of the present invention, it is apparent that the same Create and modify. In particular, with respect to the various functions performed by the above-described components (components, devices, circuits, etc.), the terms used to describe the components (including for a "means"), unless otherwise stated Reference is made to any component that corresponds to performing the component-specific function (i.e., functionally equivalent), even if it is not structurally equivalent to the disclosed structure that performs the functions of the exemplary embodiments of the invention exemplified herein. In addition, although a special feature of the present invention The disclosure is only by reference to one of the embodiments, but may be combined with one or more other features of other embodiments as long as it is needed and advantageous for any particular or particular application.

Claims (20)

An ion source liner comprising: a flat plate having an exposed surface, the exposed surface being configured to be exposed to a plasma generated in an ion source, and at least partially arresting the plasma, wherein the exposed surface is a first surface defining, wherein the plate includes a hole through the first surface, and wherein the hole is configured to pass through the hole; An electrode is passed through and an annular gap is left between the electrode and the hole, and a lip surrounds the hole and extends outwardly from the first surface. The ion source lining of claim 1, wherein the first surface has a recess defined therein, wherein the recess comprises a second surface, the second surface being recessed from the first surface by a first distance And wherein the lip extends a second distance from the second surface toward the first surface. The ion source liner of claim 2, wherein one or more of the first surface and the second surface are generally planar. The ion source liner of claim 2, wherein the first distance is about twice the second distance. The ion source liner of claim 2, wherein the lip comprises a third surface adjacent a periphery of the hole. An ion source liner as in claim 5, wherein the third surface is generally planar. An ion source liner as in claim 2, wherein the depression is generally U-shaped when viewed along an axis of the aperture. An ion source comprising: An arc chamber having a body defining an interior region of the arc chamber; one or more liners operatively coupled to the body of the arc chamber, wherein the one or more liners are generally Defining an exposed surface of the inner region of the arc chamber, and wherein the exposed surface is configured to be exposed to a plasma generated in the inner region of the arc chamber and at least partially arrest the plasma; An electrode comprising a shaft portion having a first diameter, wherein the shaft portion passes through one of the body and the one or more linings, wherein the electrode is electrically isolated from the body, and wherein the one or more One of the inner liners includes a flat plate having a first surface, the first surface having a recess having a second surface defined therein, wherein a hole is otherwise defined through the recess and Forming the shaft portion through, wherein the hole has a second diameter greater than the first diameter and defining an annular gap therebetween between the plate and the shaft portion, and wherein the plate includes a lip Shape, which is from the second Facing the first surface extends, wherein the lip-shaped member surrounds the hole within the recess and substantially prevent particulate contaminants from entering the terms of the annular gap. The ion source of claim 8, wherein the second surface is recessed from the first surface by a first distance, and wherein the lip extends a second distance from the second surface toward the first surface. The ion source of claim 9, wherein one or more of the first surface and the second surface are substantially planar. The ion source of claim 9, wherein the first distance is about twice the second distance. The ion source of claim 9, wherein the lip comprises a third surface adjacent a periphery of the hole. The ion source of claim 9, wherein the third surface is generally planar. The ion source of claim 9, wherein the recess is generally U-shaped when viewed along an axis of the hole. An ion source according to claim 8 wherein the plate defines a bottom surface in the inner region of the arc chamber, and wherein the lip generally prevents particulate contaminants from falling into the annular gap due to gravity . An ion source according to claim 8 wherein the lip has a third diameter associated therewith, wherein the electrode comprises a repeller having a head that is exposed to the The plasma within the inner region of the arc chamber, wherein the head has a fourth diameter, and wherein the fourth diameter is greater than the third diameter. An ion source processing chamber comprising: an electrode having a shaft portion and a head; and an inner liner having a hole therethrough, wherein the electrode passes through the hole and defines an annular gap on the shaft portion And the hole, and wherein the liner comprises a recess having a lip extending from the recess to substantially surround the hole and substantially avoiding particulate contaminants passing through the hole hole. The ion source processing chamber of claim 17, wherein the electrode comprises a repeller device, wherein the repeller device comprises a repeller electrode operatively coupled to the shaft portion, and wherein the repeller The diameter of the electrode is larger than the diameter of the hole, and wherein the diameter of the shaft portion is smaller than the diameter of the hole. An ion source processing chamber as claimed in claim 18, wherein the diameter of the lip is interposed Between the diameter of the repeller electrode and the diameter of the hole. The ion source processing chamber of claim 17, wherein the liner comprises a first surface, wherein the recess comprises a second surface, and wherein the lip extends from the first surface toward the second surface to About half the distance.