Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/02—Details
  • H01J37/04—Arrangements of electrodes and associated parts for generating or controlling the discharge, e.g. electron-optical arrangement or ion-optical arrangement
  • H01J37/08—Ion sources; Ion guns
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
  • C23C14/48—Ion implantation
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/30—Electron-beam or ion-beam tubes for localised treatment of objects
  • H01J37/317—Electron-beam or ion-beam tubes for localised treatment of objects for changing properties of the objects or for applying thin layers thereon, e.g. for ion implantation
  • H01J37/3171—Electron-beam or ion-beam tubes for localised treatment of objects for changing properties of the objects or for applying thin layers thereon, e.g. for ion implantation for ion implantation
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/30—Electron-beam or ion-beam tubes for localised treatment of objects
  • H01J37/317—Electron-beam or ion-beam tubes for localised treatment of objects for changing properties of the objects or for applying thin layers thereon, e.g. for ion implantation
  • H01J37/3174—Particle-beam lithography, e.g. electron beam lithography
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
  • H01J2237/02—Details
  • H01J2237/022—Avoiding or removing foreign or contaminating particles, debris or deposits on sample or tube
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
  • H01J2237/02—Details
  • H01J2237/022—Avoiding or removing foreign or contaminating particles, debris or deposits on sample or tube
  • H01J2237/0225—Detecting or monitoring foreign particles

Definitions

• the present invention relates generally to ion implantation systems, and more specifically to improved systems and methods for reducing residue buildup in such ion implantation systems.
• ion implantation systems are used to implant dopant elements into work pieces (e.g., semiconductor wafers, display panels, glass substrates). These ion implantation systems are typically referred to as "ion implanters”.
• Ion dose and ion energy are two variables commonly used to characterize an ion implantation carried out by an ion implanter.
• the ion dose is associated with the quantity of ions implanted into a region of a work piece, and is usually expressed as a number of dopant atoms per unit area of work piece material (e.g., 10 18 boron atoms/cm 2 ).
• Ion energy is associated with a depth at which the ions are implanted beneath a surface of a work piece.
• ion implanter e.g., ion source
• residue buildup After some time (e.g., 10-20 hours), the residue can impede operation of the ion source and reduce beam current.
• Some techniques disclosed herein facilitate cleaning of residue from a molecular beam component.
• a molecular beam is provided along a beam path, causing residue build up on the molecular beam component.
• the molecular beam component is exposed to a plasma comprising fluorine.
• different kinds of plasma can be selectively generated to clean different kinds of residue on the molecular beam component.
• a reactive gas delivery system includes a flow controller that supplies various types of gas to one or more plasma chambers.
• the flow controller selectively delivers some of the gases, such as boron compounds and carbon compounds, to generate plasma discharges that are subsequently used to achieve ion implantation into one or more work pieces.
• the boron and/or carbon compounds can cause different types of residues to buildup in the system.
• the flow controller also can selectively deliver different types of cleaning gases to one or more plasma chambers to generate different plasma discharges to selectively remove the different types of residue from the system.
• Fig. 1 is an embodiment of an ion implantation system.
• Fig. 2 is an embodiment of an ion implantation system that includes a reactive gas delivery system in accordance with some embodiments.
• Fig. 3 is a flow chart of a method for limiting or cleaning residue buildup from an ion implanter component according to an embodiment.
• Fig. 4 is a flow chart of another method for limiting or cleaning residue buildup from an ion implanter component according to an embodiment.
• Fig. 5 illustrates an isometric perspective view of an exemplary ion source to generate the molecular beam in accordance with one embodiment.
• Fig. 6 illustrates a cross sectional perspective view of an exemplary ion source to generate the molecular beam in accordance with one embodiment.
• Fig. 7 illustrates one mechanism of generating a cleaning plasma in close proximity to the ion source components that are susceptible to residue buildup.
• the present invention is directed generally towards residue removal techniques that are applicable to ion implantation systems. More particularly, the system and methods of the present invention provide an efficient way to reduce residue generated by large molecular species, such as, for example: carborane; decaborane; octadecaborane and icosaboranes; hydrocarbons such as C7H7 and CioHi4, as well as standard ionization gases for the production of small molecular ion implant species (e.g., BF 2 , and monatomic species), such as boron trifluoride, phosphine and arsine.
• large molecular species such as, for example: carborane; decaborane; octadecaborane and icosaboranes; hydrocarbons such as C7H7 and CioHi4, as well as standard ionization gases for the production of small molecular ion implant species (e.g., BF 2 , and monatomic species), such as boro
• Fig. 1 illustrates an ion implantation system 10 having a terminal 12, a beamline assembly 14, and an end station 16.
• an ion source 18 in the terminal 12 is coupled to a power system 20 to ionize a dopant gas and form an ion beam 22 using small molecules (such as BF 2 , , and monatomic species) or large molecules.
• the beam 22 is passed through the beamline assembly 14 before bombarding a work piece 24 (e.g., a
• the beamline assembly 14 has a beamguide 26 and a mass analyzer 28.
• a dipole magnetic field is established in the mass analyzer 28 during operation. Ions having an inappropriate charge-to-mass ratio collide with the sidewalls 32a, 32b; thereby leaving only the ions having the appropriate charge-to-mass ratio to pass through a resolving aperture 30 and into the work piece 24.
• the beam line assembly 14 may also include various beam forming and shaping structures extending between the ion source 18 and the end station 16, which maintain the ion beam 22 and bound an elongated interior cavity or passageway 36 through which the beam 22 is transported to the work piece 24 supported in the end station 16.
• a vacuum pump 34 typically keeps the ion beam transport
• passageway 36 at vacuum to reduce the probability of ions being deflected from the beam path through collisions with air molecules.
• the implanter 10 may employ different types of end stations 16.
• "batch" type end stations can simultaneously support multiple work pieces 24 on a rotating support structure, wherein the work pieces 24 are rotated through the path of the ion beam until all the work pieces 24 are completely implanted.
• a "serial” type end station supports a single work piece 24 along the beam path for implantation, wherein multiple work pieces 24 are implanted one at a time in serial fashion, with each work piece 24 being completely implanted before implantation of the next work piece 24 begins.
• various contaminants e.g., boron, carbon, or other dopant material from the ion source 18
• boron species e.g., boron, carbon, or other dopant material from the ion source 18
• boron-based residue can build up in an ion source; while when carbon species are present in the beam 22 carbon-based residue can similarly build up.
• Other types of residue can also build up depending on the types of implantation carried out. Aspects of this disclosure relate to techniques for removing or otherwise limiting such residue.
• Fig. 2 illustrates an example of an ion implantation system 150 that tends to limit build-up of residue, thereby helping to ensure reliable operation of the system over a long period of time.
• Fig. 2's ion implantation system 150 includes a reactive gas delivery system 200.
• the reactive gas delivery system 200 includes a flow control assembly 202 that typically comprises mechanical and/or electro-mechanical components (e.g., valves, pumps and flow tubes) to deliver various gases to the ion implantation system 150 under the direction of a controller 204.
• the various gases can be selectively delivered to generate different plasma discharges that are adapted to remove different types of residue that may build up on ion system components.
• an afterglow of the plasma can actually clean the residue.
• plasma is used for an active generation region where RF, or microwaves actually impinge and create the plasma (consisting of ions, electrons, metastables, neutrals, etc.), whereas afterglow is a downstream region where the species are no longer created, but are forced due to diffusion and are effectively utilized.
• the flow control assembly 202 is shown coupled to first and second dopant gas supplies (206, 208), as well as first and second cleaning gas supplies (210, 212).
• the gas supplies 206-212 are stored in gas canisters, although the desired gases can also be generated in situ by carrying out appropriate chemical reactions and/or ionizations. It will be appreciated that although the illustrated embodiment depicts only first and second dopant gas supplies (206, 208) and first and second cleaning gas supplies (210, 212), any number of such gas supplies may be included to carry out desired implantation and cleaning functionality.
• controller 204 instructs the flow control assembly
• the first dopant gas supply 206 comprises molecular boron (e.g., decaborane (BioH 14 ), octadecaborane (Bi 8 H 2 2)) and the second dopant gas supply 208 comprises molecular carbon (e.g., C7H7, Ci 6 Hi 4 ).
• the molecular boron can be supplied to the plasma chamber to generate a first plasma, which can be extracted to form a first type of ion beam 22 that is suitable for forming an n-type region on the work piece(s).
• the molecular carbon can be supplied to the plasma chamber to generate a second plasma, which can be extracted to form a second type of ion beam 22 that is suitable for forming compressive strain regions in semiconductor devices.
• the first and second types of ion beams include different molecular species
• the first and second ion beams can form different kinds of residue in the system. Unless appropriate measures are taken, these different kinds of residue can buildup to push beam current beneath desired levels.
• the controller 204 can initiate a cleaning process to reduce any such residue.
• the controller 204 instructs the flow control assembly 202 to pump the plasma chamber down to vacuum and then supply a first cleaning gas from the first cleaning gas supply 210 to a second plasma source that is used exclusively for cleaning purposes.
• the first cleaning gas comprises a fluorocarbon (having molecular formula C a F b , where a and b are integers) and/or a hydro-fluorocarbon (having molecular formula C x F y H z , where x, y, and z are integers).
• the first cleaning gas When this first cleaning gas is ionized and plasma is generated therefrom, its free reactive fluorine atoms can remove the first type of residue (e.g., boron-based residue).
• the first cleaning gas may be substantially, if not completely, free of NF 3 gas; thereby alleviating the need for special gas handling techniques, reducing costs, and tending to make the inventive techniques more environmentally friendly in some respects than NF3-based cleaning techniques.
• the controller 204 can also instruct the flow control assembly 202 to pump the plasma chamber down to vacuum, and then supply a second cleaning gas from the second cleaning gas supply 212 to the second plasma source.
• the second cleaning gas may comprise oxygen, thereby generating a plasma comprising atomic oxygen that removes the second type of residue (e.g., carbon- based residue) from an ion source component.
• the second cleaning gas may also be substantially, if not completely, free of NF 3 gas.
• this disclosure facilitates reliable operation for the ion implantation system.
• this concept is discussed above with respect to only first and second cleaning plasma discharges to clean first and second types of residue, respectively, this concept is extendable to any number of cleaning plasma discharges operable to clean any number of types of residue, respectively.
• Fig. 2 depicts a residue detection sensor 214 located in an exhaust system 216 in fluid communication with the plasma chamber in the ion source 18.
• Fig. 2 depicts an embodiment where the residue detection sensor 214 resides in the exhaust system 216, in other embodiments the residue detection sensor could be located in other regions.
• a residue detection sensor 214 could also be located downstream of the ion source, such as in the beamline assembly 14, for example.
• the residue detection sensor 214 can enable optical spectroscopic analysis that makes use of a secondary plasma source (not shown) in the exhaust system 216.
• the residue detection sensor 214 analyzes exhaust from the plasma chamber in the ion source for trace amounts of residue.
• residue if present
• residue emits photons/light at a predetermined quantized energy level indicative of residue.
• the light emitted from different types of residue serve as a kind of "fingerprint" by which different types of residue can be identified, thereby allowing the controller 204 to select an appropriate cleaning gas to remove the particular type of residue detected.
• the optical fingerprint drops below a certain preset threshold, which can allow the controller 204 to terminate the cleaning process, thereby providing real-time control of the length of cleaning required.
• the residue detection sensor 214 can enable residual mass analysis that makes use of a secondary plasma source and a quadrupole magnet (not shown) located in the exhaust system 216.
• RAA residual gas analysis
• the molecular constituents of the exhaust are again analyzed for trace amounts of residue, but this time based on the respective atomic masses of the molecular constituents.
• the masses that are detected serve as a kind of "fingerprint" by which different types of residue can be identified, thereby allowing the controller 204 to select an appropriate cleaning gas to remove the particular type of residue detected.
• the residue detection sensor 214 can comprise a temperature sensor.
• a residue molecule disassociates in the presence of reactive species, the chemical reactions are typically exothermic, which tend to heat up the surfaces upon which the residue had formed according to a characteristic temperature curve, which can be indicative of whether residue is being removed.
• the temperature sensor typically mounted to the ion source components shows no further rise in temperature, the exothermic chemical reactions between the residue and reactive cleaning plasma are complete, and the temperature sensor's data may be used to stop the cleaning process.
• Figs. 3-4 show methods 300, 400 in accordance with some aspects. While these methods are illustrated and described below as a series of acts or events, the present disclosure is not limited by the illustrated ordering of such acts or events. For example, some acts may occur in different orders and/or concurrently with other acts or events apart from those illustrated and/or described herein. In addition, not all illustrated acts are required, and one or more of the acts depicted herein may be carried out in one or more separate acts or phases.
• Fig. 3 illustrates a method 300 that begins at 302 when a desired implantation routine is selected.
• the desired implantation routine may deliver a desired n-type doping profile, a desired p-type doping profile, or some other type of implant, such as a carbon implant, for example.
• a first type of implantation routine is selected, the method proceeds to 304 and one or more workpieces are implanted with a molecular boron ion beam. This implantation may cause a first type of residue to build up on one or more ion beam components.
• the molecular beam component having the first type of residue thereon is exposed to a first afterglow (or a first cleaning plasma), which comprises reactive dissociated atomic fluorine radicals to facilitate removal of the residue.
• a first cleaning plasma which gives rise to the first afterglow may be generated by using a gas mixture that comprises a
• exposure to the first afterglow is selectively ended based on whether a first predetermined condition is met.
• the first predetermined condition is indicative of an extent of removal of the residue.
• the first condition relates to whether a predetermined time has expired as measured from a starting time of the exposure to the first afterglow.
• the first condition relates to whether optical spectroscopic analysis using a secondary plasma source located preferably, though not limited to, in the exhaust line indicates whether the first afterglow has completely removed the residue from the ion source
• the first condition relates to whether a residual gas mass analysis indicates whether the first afterglow has completely removed the residue from the ion source component.
• the first condition relates to whether a temperature measurement indicates whether the first afterglow has completely removed the residue from the ion source component. Note that the first condition could also relate to less than a complete removal of the residue in these and other embodiments.
• the method determines if another implantation is required. If so, the method returns to 302 and selects another implantation routine to be carried out on the same or different workpiece as previously implanted.
• a second implantation routine is selected at 302, at 312 one or more workpieces are implanted with a molecular carbon beam. This forms a second residue on the ion beam component.
• the ion beam component is exposed to a second afterglow (or a second cleaning plasma) comprising reactive dissociated atomic oxygen radicals to facilitate removal of the second residue formed, for example, during the molecular carbon implant.
• exposure to the second afterglow is selectively ended based on whether a second predetermined condition is met, where the second predetermined condition is indicative of an extent of removal of the second residue.
• the second condition relates to whether a predetermined time has expired as measured from a starting time of the exposure to the second afterglow.
• the second condition relates to whether optical spectroscopic analysis using a secondary plasma source indicates whether the second afterglow has completely removed the residue from the ion source component.
• the second condition relates to whether a residual gas mass analysis indicates whether the second afterglow has completely removed the residue from the ion source component. In still another embodiment, the second condition relates to whether a temperature measurement indicates whether the second afterglow has completely removed the residue from the ion source component. Note that the second condition could also relate to less than a complete removal of the residue in these and other embodiments.
• Fig. 4 shows another method 400 in accordance with some embodiments.
• the method 400 starts at 402 when a first molecular beam is generated, where the first molecular beam includes a first molecular species.
• the remaining acts of method 400 are described below with respect to an implementation where the first molecular species is boron, but other molecular species could also be used.
• the first molecular beam is provided along a beam path, which causes a first residue to buildup on molecular beam components.
• the molecular beam components are exposed to a first cleaning plasma to facilitate removal of the first residue.
• the first cleaning plasma includes fluorine ions and/or fluorine radicals, such as can be generated from fluorocarbons or hydro-fluorocarbons, for example.
• exposure to the first cleaning plasma is selectively ended based on whether a first predetermined condition is met.
• the first condition can relate to time, a spectrograph ⁇ optical analysis, a residual gas mass analysis, or a temperature analysis.
• a second molecular ion beam is generated, which includes a second molecular species.
• the second molecular species is described as carbon, which is one non-limiting example.
• the second molecular ion beam is provided along the beam path, causing a second residue to buildup on the molecular beam component.
• the molecular beam component is selectively exposed to a second cleaning plasma that differs from the first cleaning plasma to facilitate removal of the second residue.
• the second cleaning plasma includes oxygen, which is one non-limiting example.
• exposure to the second cleaning plasma is selectively ended based on whether a second predetermined condition is met.
• the second condition can relate to time, a spectrographic optical analysis, a residual gas mass analysis, or a temperature analysis.
• each exposure can be tailored to remove a different type of residue from the ion source component, thereby reducing residue buildup so reliable operation can be achieved.
• Fig. 4 the method illustrated in Fig. 4 is carried out after a batch (or multiple batches) of wafers has been implanted with the first and/or second species, as long as beam current can be maintained.
• both the first and second cleaning processes may be employed in a serial manner at a predetermined maintenance schedule (e.g., once a set number of wafers have been implanted). It is possible that the cleaning processes may be alternately carried out several times to ensure any residue is removed in a desired manner.
• Figs. 5-6 show an embodiment of an ion source 500 that can be used in accordance with some embodiments. It should be noted that the ion source 500 depicted in Figs. 5-6 is provided for illustrative purposes as merely one type of ion source that is susceptible to residue buildup (e.g., on aperture 520) and is not intended to include all aspects, components, and features of an ion source.
• exemplary ion source 500 is depicted so as to facilitate a further understanding of one type of ion source that could be used in conjunction with some embodiments.
• the ion source 500 comprises a first plasma chamber 502 situated adjacent a second plasma chamber 516.
• the first plasma chamber 502 includes a gas source supply line 506 and is a configured with a plasma generating component 504 for creating plasma from a first source gas.
• the gas supply line selectively carries a dopant gas (e.g., from the first and/or second dopant gas supply 206, 208 of Fig. 2).
• Plasma from the secondary cleaning-plasma-source e.g., which uses gas supplied from the first and/or second cleaning gas supply 210, 212 of Fig. 2 is carried to the first plasma chamber 502 through
• the plasma generating component 504 can comprise a cathode
• the plasma generating component 504 may include an RF induction coil antenna that is supported having a radio frequency conducting segment mounted directly within a gas confinement chamber to deliver ionizing energy into the gas ionization zone.
• the first, or electron source, plasma chamber 502 defines an aperture 512 forming a passageway into a high vacuum region of an ion implantation system, i.e. a region wherein pressure is much lower than the pressure of the source gas in the first plasma chamber 502.
• the electron source plasma chamber 502 also defines an aperture 514 forming an extraction aperture for extracting electrons from the electron source plasma chamber 502.
• the extraction aperture 514 is provided in the form of a replaceable anode element 510 as illustrated in FIG. 6, having an aperture 514 formed therein.
• the electron source plasma chamber 502 can be configured to have a positively biased electrode 519 (relative to the cathode 508) for attracting electrons from the plasma in a so-called non-reflex mode.
• the electrode 519 can be biased negatively relative to the cathode 508 to cause electrons to be repelled back into the electron source plasma chamber 502 in a so-called reflex mode. It will be understood that this reflex mode configuration would require proper biasing of the plasma chamber walls, together with electrical insulation and independent biasing of the electrode 519.
• the ion source 500 also includes a second, or ion source chamber 516.
• the second ion source plasma chamber 516 includes a second gas source supply line 518 for introducing a source gas into the ion source plasma chamber 516 and is further configured to receive electrons from the electron source plasma chamber 502, thereby creating plasma therein via the collisions between the electrons and the second source gas.
• the second gas supply source line 518 can selectively carry a dopant gas (e.g., from the first and/or second dopant gas supply 206, 208 of Fig. 2) and/or a cleaning plasma from the secondary cleaning-plasma source (e.g., that uses gas from the first and/or second cleaning gas supply 210, 212 of Fig. 2) to the second plasma chamber 516.
• the second, or ion source, plasma chamber 516 defines an aperture 517 aligned with the extraction aperture 514 of the first plasma chamber 502, forming a passageway therebetween for permitting electrons extracted from the first plasma chamber 502 to flow into the second plasma chamber 516.
• the ion source plasma chamber 516 is configured to have a positively biased electrode 519 for attracting electrons injected into the ion source plasma chamber 516 in a so-called non-reflex mode to create the desired collisions between electrons and gas molecules to create ionization plasma.
• the electrode 519 can be biased negatively to cause electrons to be repelled back into the ion source plasma chamber 516 in a so-called reflex mode.
• An extraction aperture 520 is configured in the second plasma chamber 516 to extract ions for formation of an ion beam for implantation.
• the second plasma chamber 516 is biased positively with respect to the first plasma chamber 502 utilizing an external bias power supply 515 (FIG. 6). Electrons are thus extracted from the electron source plasma chamber 502 and injected into the ion source plasma chamber 516 where collisions are induced in the second plasma chamber 516 between the electrons provided by the first plasma chamber 502 and the supply gas supplied to the second plasma chamber 516 via the second gas source supply line 518, to create a plasma.
• first plasma chamber 502 and the second plasma chamber 516 can have three open boundaries: a gas inlet (e.g., a first gas supply inlet 522 and a second gas supply inlet 524), an opening to a high vacuum area (e.g., pumping aperture 512 and extraction aperture 520) and a common boundary apertures 514 and 517 forming the common passageway between the first and second plasma chambers, 502 and 504, respectively.
• a gas inlet e.g., a first gas supply inlet 522 and a second gas supply inlet 524
• an opening to a high vacuum area e.g., pumping aperture 512 and extraction aperture 520
• common boundary apertures 514 and 517 forming the common passageway between the first and second plasma chambers, 502 and 504, respectively.
• Both plasma chambers 502, 516 also share a magnetic field oriented along the extraction aperture, provided by a standard Axcelis source magnet, depicted by reference numeral 530. It is well known that the ionization process (and in this case the electron generating process) becomes more efficient by inducing a vertical magnetic field in the plasma generating chamber.
• electromagnet members 530 are positioned outside of the first and second plasma chambers, 502 and 516 respectively, preferably along the axis of the shared boundary therebetween. These electromagnet elements 530 induce a magnetic field that traps the electrons to improve the efficiency of the ionization process.
• Figure 7 show one embodiment where the cleaning plasma is actually generated in a secondary plasma source 702 positioned within the gas supply source line 518.
• the reactive gases e.g., supplied from the gas cleaning supplies 210, 212 in Fig. 2
• the gas supply source line 518 comprises a dielectric conduit 704 coupled laterally between first and second conductive conduits 706, 708, respectively.
• the first conductive conduit 706 may be referred to as a gas supply line
• the second conductive conduit 708 may be referred to as an afterglow supply line.
• the dielectric conduit 704 can comprise sapphire (for fluorine compatibility) and the conductive conduits 706, 708 can comprise metal.
• An inductive coil 710 is also wrapped around the gas supply source line 518 very near the aperture 524.
• an RF power supply 712 which is coupled to the inductive coil 710 via a matching network 714, is activated, a highly concentrated plasma is generated in a region 716 in the gas supply source line 518.
• the plasma is generated very close to the first and/or second chamber 502, 516 where the reactive species are to be used to clean residue.
• Fig. 7 shows an embodiment that includes an RF coil 710, other embodiments can use with a microwave source or other plasma generating component that is close to the opening 524.
• a secondary plasma source was located at a far end of the gas/afterglow source supply line 518.
• a plasma was generated at the far end of the gas/afterglow source supply line 518 (e.g., often about 2 meters from the ion source)
• conductance and surface recombination losses on the walls of the gas/afterglow supply source line 518 cause the loss of a significant percentage of the reactive gas species generated in the plasma source.
• Fig. 7's arrangement helps to ensure that more reactive gas molecules diffuse efficiently to the ion source and thereby help to facilitate effective cleaning of residue from components in the ion source.
• generating the cleaning plasma so close to the source components 516 and 502 may improve efficiency by not requiring large flow of cleaning gas, or by significantly reducing RF power usage.

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• Chemical & Material Sciences (AREA)
• Analytical Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Electron Sources, Ion Sources (AREA)
• Plasma Technology (AREA)
• Physical Vapour Deposition (AREA)
• Cleaning In General (AREA)

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