TWI463516B - Method of ion source cleaning in semiconductor processing systems - Google Patents

Description

Method of cleaning an ion source in a semiconductor processing system

The present invention relates to the monitoring, control, and cleaning of materials deposited on components of semiconductor processing systems, particularly ion implantation systems.

Ion implantation is used in the fabrication of integrated circuits to accurately introduce a controlled amount of dopant impurities into a semiconductor wafer and is an important process in microelectronic/semiconductor production. In such implant systems, an ion source ionizes a desired dopant element gas into an ion and the plasma is extracted from the source in the form of an ion beam having the desired energy. Extraction is achieved by applying a high voltage across a suitably shaped extraction electrode that combines the multiple wells into a channel for the extraction beam. The ion beam is then oriented on a surface of the workpiece, such as a semiconductor wafer, to implant a doping element into the workpiece. The ions in the beam penetrate the surface of the workpiece to form a region of the desired conductivity.

Several types of ion sources are commonly used in commercial ion implantation systems, including: Freeman and Bernas types that use thermoelectric electrodes and are powered by an arc, microwave types that use a magnetron, indirectly heated cathode sources, and RF plasma source, all of which are typically operated in a vacuum. The ion source generates ions by introducing electrons into a vacuum chamber filled with a dopant gas (generally referred to as "feed gas"). The collision of electrons with dopant atoms and molecules in the gas causes the generation of ionized plasma consisting of positive and negative dopant ions. An extraction electrode having a negative or positive bias will respectively allow the positive or negative ions to pass through the aperture as a collimated ion beam and exit the ion source, which is accelerated toward the workpiece. The material gases include, but are not limited to, BF ₃ , B ₁₀ H ₁₄ , B ₁₈ H ₂₂ , PH ₃ , AsH ₃ , PF ₅ , AsF ₅ , H ₂ Se, N ₂ , Ar, GeF ₄ , SiF ₄ , O ₂ , H ₂ , and GeH ₄ .

Currently, there are 10-15 implant steps in the fabrication of prior art devices. Increasing wafer size, reducing critical dimensions, and increasing the complexity of the circuit are now being proposed for better processing control of ion implantation tools, release of low energy high beam currents, and reduction in mean time between failure (MTBF). More requirements.

The most demanding components of the ion implanter tool include: an ion source that must be serviced after approximately 100 to 300 hours of run time (depending on its operating conditions); extraction electrodes and high voltage insulators that are running hundreds of Cleaning is usually required after an hour; the front stage of the ion implantation vacuum system and the vacuum pump, including the ion source turbo pump and its associated foreline. In addition, various components of the ion source, such as filaments, cathodes, and the like, may need to be replaced after operation.

Ideally, all of the feedstock molecules will be ionized and extracted, but in practice a certain amount of decomposition of the feedstock will occur, which results in deposition and contamination on the ion source region. For example, a residue of phosphorus (e.g., derived from the use of a source gas such as phosphine) is rapidly deposited on the surface of the ion source region. This residue can form on the low voltage insulator in the ion source, causing an electrical short, which can interrupt the arcing required to generate hot electrons. This phenomenon is commonly referred to as "glitching" and is an important factor in ion beam instability and may eventually cause premature failure of the source. The residue is also formed on the high voltage components of the ion implanter, such as the surface of the insulator or extraction electrode of the source, causing high energy, high voltage power generation. Such an electric flower is another factor in beam instability, and the energy released by such electro-sparks can damage sensitive electronic components, resulting in increased equipment failure and poor MTBF.

For the implantation of bismuth (Sb+) using Sb ₂ O ₃ as a solid doping material, another common problem occurs, which can be deteriorated by flowing boron (B) even after only a few hours of Sb+ implantation. The boron beam current can significantly degrade the performance and lifetime of the significantly damaged ion source. The cause of such performance degradation is due to excessive deposition of Sb on the chamber of the source and its components. Since the yield is reduced due to more frequent preventive maintenance or less beam current, the failure of the ion source significantly reduces the productivity of the implanter. Since the implantation of Sb is widely used in similar bipolar devices and also serves as an n-type doping for shallow junction formation of MOS (Metal Oxide Semiconductor) devices, there is a need in the art to develop a method. That is, when Sb+ is used as a dopant, particularly when Sb is converted to B after implantation, the method can remove deposited Sb from the chamber of the source and its components.

In addition, dopant atoms (eg, B, Ge, Si, P, and As) may be deposited in the ion source turbo pump, downstream of its associated vacuum foreline, and in a low vacuum pump downstream of the foreline. Over time, the deposits accumulate and require cleaning, which was done manually in the past. However, some deposits (such as solid phosphorus) are sparking and may catch fire during manual maintenance operations. This is not only a fire hazard, but it can also release toxic compounds. There is therefore a need in the art to develop an improved process that can use a gas cleaning agent to wash the deposits in situ as desired.

In another cause of ion source failure, various materials (eg, tungsten, W) can accumulate on the cathode during long-term ion implantation. Once the materials have accumulated to a critical level, the cathode power source can no longer maintain a temperature sufficient to meet the beam current set point. This causes a loss of ion beam current and requires replacement of the ion source. Degraded ion source performance and reduced lifetime shorten the productivity of the ion implanter system.

Another cause of ion source failure is etching (or sputtering) of the cathode material. For example, a metal material (eg, W, Mo, etc.) from the cathode is sputtered by ions in the plasma in the arc chamber. Since sputtering is controlled by the heaviest ions in the plasma, the sputtering effect may deteriorate as the ion mass increases. In fact, the sputtering of a continuous material "thins" the cathode, which ultimately results in the formation of a hole in the cathode ("cathode through"). As a result, the performance and lifetime of the ion source are greatly reduced. Therefore, the art continues to seek ways to maintain the balance between the accumulation of material on the cathode and the corrosion to extend the life of the ion source.

Other residues may result from the reaction between the ion source material and the components of the ion implantation system, depending on the conditions within the system. Such reactions can result in deposits of residues on additional components of the system. For example, tungsten whiskers can be formed on the arc chamber extraction holes, resulting in beam non-uniformity problems.

Sediments are common on components of ion sources, such as filaments and reflector electrodes. Such internal deposits are generally composed of arc chamber materials, and the most common is when a high plasma power source of a feedstock having a fluoride source is operated in conjunction with an arc chamber of tungsten or molybdenum. Although the ion source of an ion implantation system using a material other than a halide source typically has an expected lifetime of about 100 hours to 300 hours, some halide containing materials (such as GeF ₄ ) are internal deposits due to ion source operation. The harmful effects of the ion source can be as low as 10 hours to 50 hours.

In addition to the operational difficulties caused by residues in the ion implanter, there are significant personnel safety issues due to the emission of toxic or corrosive vapors when components are removed for cleaning. Safety issues can occur anywhere in the residue, but are of particular concern in the ion source region because the ion source is the most frequently maintained component of the ion implanter. To minimize downtime, contaminated ion sources are often removed from the implanter at temperatures significantly above room temperature, which increases vapor emissions and deepens safety issues.

Existing methods of dealing with the above difficulties have included attempts to prevent the formation of deposits and to clean deposits produced on the extraction electrode and ion source (i.e., on the extraction electrode, as disclosed in U.S. Patent Application No. 2006/0272776, issued U.S. Patent application 2006/0272775 and the published international patent application WO 2005/059942 A2). However, there is still a need for additional processes to clean all elements of the ion implantation system.

It is therefore desirable in the field of ion implantation to provide an off-site cleaning method with a separate cleaning station whereby the contaminated components that have been removed from the implanter can be safely cleaned without any mechanical wear, Mechanical wear can damage delicate components such as graphite electrodes. Therefore, providing an off-line cleaning station will also be a significant advancement in the field of ion implantation, which can be used to selectively and non-destructively clean components after they are removed from the implant system with minimal downtime.

Providing an in situ cleaning method would also be a significant advancement in the field of ion implantation for effectively and selectively removing unnecessary implants throughout the implantation process (especially the ion Source area) residue of deposition. This in-situ cleaning improves personnel safety and facilitates the operation of stable, uninterrupted implant equipment.

An in-situ cleaning process can be performed without disassembling the processing chamber. For the in-situ process, a gaseous reagent is passed from the processing chamber to remove the accumulated film in a continuous, pulsed or mixed continuous-pulse manner. Depending on the situation, a plasma may or may not be produced during such a cleaning process.

A plasmaless or dry cleaning method using materials containing chlorine trifluoride (ClF ₃ ) and other fluorine sources (eg CF ₄ , NF ₃ , C ₂ F ₆ , C ₃ F ₈ , SF ₆ and ClF ₃ ) is available Removing solid residue from the semiconductor processing chamber, for example by reacting with a solid residue to form a volatile reaction product that is removable from the processing chamber by vacuum or other removal conditions, and in such a In this case, such cleaning reagents may require high temperature cleaning conditions. See Y. Saito et al., "Plasmaless Cleaning Process of Silicon Surface Using Chlorine Trifluoride", APPLIED PHYSICS LETTERS, Vol. 56(8), pp. 1119-1121 (1990); see also DE Ibbotson et al., "Plasmaless Dry Etching of Silicon" With Fluorine-Containing Compounds", JOURNAL OF APPLIED PHYSICS, Vol. 56 (10), pp. 2939-2942 (1984).

U.S. Patent No. 4,498,953 describes an in-situ cleaning method, wherein one interhalogen compound (e.g. _{BrF 5, BrF 3, ClF 3} , or IF ₅₎ flows continuously through the processing chamber while the chamber is maintained at a predetermined of pressure. At the end of the treatment, the flow of the inter-halogen compound gas is terminated. Such processes can produce by-products containing Cl, Br, or I, along with fluorine-containing by-products, thereby producing a large amount of hazardous waste requiring treatment or other disposal. In addition, such continuous flow cleaning is carried out under very low pressure conditions, at which the cleaning efficiency is substantially reduced.

In certain applications, the ion source, has a BF _3, PH _3, and / or strategically ordered AsH ₃ in order to achieve a longer life of the ion source.

The use of fluorine- or fluorine-containing interhalogen compounds for cleaning semiconductor processing equipment has associated deficiencies that limit its commercial viability. Fluorine- or fluorine-containing interhalogen compounds (including ClF ₃ ) are highly corrosive. In addition, interhalogen compounds are strong irritants to the human respiratory tract. For example, a threshold human tolerance level for ClF ₃ vapor can be as low as 100 ppb and an LC50 of 1 hour at 300 ppm.

The art continues to seek new cleaning reagents as well as off-site and in-situ systems and methods, as well as related monitoring and control devices and methods.

The present invention generally relates to apparatus and methods for monitoring, controlling, and cleaning ion implantation systems or components thereof, as well as compositions useful for such cleaning.

The one-state sample invention provides a method of monitoring the filament state of an ion implantation system during system operation, the method comprising: (a) using in an arc chamber of an ion source sufficient to generate one in the arc chamber An initial current of the plasma is supplied to the one pole; (b) measuring the current input to the filament at a predetermined time of continuous plasma generation to maintain the plasma in the arc chamber; (c) will be at the predetermined time The measured current input is compared to the initial current, and (d) determining, based on such comparison, whether material has been deposited onto the filament or whether etching of the filament has occurred, wherein the predetermined current is at the predetermined time A larger current indicates deposition of material on the filament, and a smaller current at the predetermined time relative to the initial current indicates etching of the filament.

In another aspect, the invention provides a method of controlling the state of a filament of an ion implantation system during operation of the system, comprising: (a) using in an arc chamber of an ion source sufficient to produce in the arc chamber An initial current of a plasma is supplied to a filament; (b) measuring a current input to the filament at a predetermined time of continuous plasma generation to maintain plasma in the arc chamber; (c) at the predetermined The time measured current input is compared to the initial current, (d) determining whether the material has been deposited onto the filament or whether the filament has been etched based on such comparison, wherein the predetermined current is at the predetermined time relative to the initial current A larger current indicates deposition of the material on the filament, and a smaller current at the predetermined time relative to the initial current indicates etching of the filament, and (e) in response to the determination, from the filament The pole removes the deposited material or deposits additional material on the filament to a degree that reestablishes the initial current input or a current input within a predetermined range of the initial current input. In another embodiment of this aspect, steps (a) through (d) can be performed during the ion implantation process; step (e) can be performed before, after or between the ion implantation processes.

In another aspect, the present invention provides a method of controlling the state of an indirectly heated cathode (IHC) source of an ion implantation system during system operation, comprising: (a) measuring by a predetermined time Cathode bias power supply to determine the power used by the indirectly heated cathode source; (b) comparing the used power to the initial power for the predetermined time; and (c) taking corrective action (i) or (ii) in response to the comparison Controlling the state of the indirectly heated cathode whereby (i) etching the indirectly heated cathode if the used power is higher than the initial power for the predetermined time; or (ii) using the power for the predetermined time Below this initial power, the indirectly heated cathode is regenerated. The initial power includes the value of the cathode bias power for a time prior to the measurement of a predetermined time, for example, it can be the power at startup, or the power under normal operating conditions, or any other predetermined time point or value. As will be understood by those skilled in the art, the cathode bias power measurement and initial power value may be in the form of a range or ranges depending on the implantation process or other conditions. The etching of (c)(i) includes operating the indirectly heated cathode at a low temperature to moderate temperature sufficient for etching. The low to medium temperatures in this regard are exemplified as being from about room temperature up to about 2000 °C. The regrowth of (c)(ii) includes flowing a fluorinated gas over the indirectly heated cathode under a plasma condition, wherein the fluorinated gas comprises one or more of the following: XeF ₂ , XeF ₄ , XeF ₆ , GeF ₄ , SiF ₄ , BF ₃ , AsF ₅ , AsF ₃ , PF ₅ , PF ₃ , F ₂ , TaF ₃ , TaF ₅ , WF ₆ , WF ₅ , WF ₄ , NF ₃ , IF ₅ , IF _7. KrF ₂ , SF ₆ , C ₂ F ₆ , CF ₄ , ClF ₃ , N ₂ F ₄ , N ₂ F ₂ , N ₃ F, NFH ₂ , NH ₂ F, BrF ₃ , C ₃ F ₈ , C ₄ F ₈ , C ₅ F ₈ , CHF ₃ , CH ₂ F ₂ , CH ₃ F, COF ₂ , HF, C ₂ HF ₅ , C ₂ H ₂ F ₄ , C ₂ H ₃ F ₃ , C ₂ H ₄ F ₂ , C ₂ H ₅ F, C ₃ F ₆ and MoF ₆ . The regrowth of (c)(ii) includes operating the indirectly heated cathode at a temperature sufficient to cause metal deposition. The high temperatures in this regard are exemplified as greater than 2000 °C. The calibration step (c) can be performed before, after or between the ion implantation processes. Additionally, for regrowth, if the implanted material is selected from one of the fluorinated gases directly described above, the correcting step can be performed during the implantation process. The method steps discussed above or elsewhere herein may be performed by appropriate control devices (such as microcontrollers, controllers, microprocessors, etc.) and associated electrical, electronic, and/or electromechanical components, which are suitably programmed And/or automatic repair or cleaning of components of the ion source, such as filaments, reflector electrodes, cathodes, and counter electrodes.

In another aspect, the invention provides for operating an arc chamber of an ion source comprising a filament or cathode (or an ion that can be etched or have deposits such as, but not limited to, counter electrodes, reflectors, and the like) An ion implantation system of other components of the source to maintain the operational efficiency of the ion source, the method comprising performing the filament or cathode or other components of the ion source as described above with a tungsten reagent under the following conditions Contact, the conditions are selected from the group consisting of:

(a) conditions for achieving deposition of tungsten on the filament;

(b) A condition for etching the deposited material from the filament.

In one embodiment of this aspect, other ion source components, such as cathodes, reflectors (which correspond to cathodes and filaments, respectively) or the like, may be provided with suitable heating elements to adjust the surface temperature of the components to select The material from it is etched or deposited thereon.

In another embodiment, the indirectly heated cathode (IHC) ion source can include two cathodes (instead of the cathode and counter electrode). During implantation, one cathode can operate as a counter cathode, and during the repair or calibration process, the temperature of the two cathodes can be controlled to deposit or etch materials as needed.

The present invention relates, in another aspect, to a method of cleaning one or more components of an ion implantation system for at least partially removing deposits associated with ionization from the one or more components, The method comprises flowing a purge gas through the system under conditions selected from the group consisting of:

(a) achieving conditions under which the material is deposited on the filament, cathode or other ion source component as described above;

(b) A condition for etching the deposited material from the filament, the cathode or other ion source components as described above.

Another aspect of the invention relates to a method of maintaining a filament of a source of ions in an arc chamber with a predetermined electrical resistance, the method comprising comparing the filament to a temperature dependent on the filament relative to the arc chamber The temperature of the wall is effective to deposit material on the filament or to effectively contact a reagent that etches material from the filament, and to control the temperature of the filament and the temperature in the wall of the arc chamber to effectively deposit on the filament or The material is etched to maintain the predetermined resistance. In general, if the temperature of the filament is sufficiently high (e.g., greater than 2000 ° C) when the wall of the arc chamber is low to moderate (less than the temperature of the filament), deposition of material on the filament occurs. If the temperature of the arc chamber wall is not considered (although the temperature of the arc chamber wall is less than or greater than the temperature of the filament is preferred) and the temperature of the filament is from low to medium (for example, less than about 1500 ° C to 2000 ° C), then A self-filament etching material occurs.

In another aspect, the present invention is directed to a method of cleaning an ion implantation system or one or more components thereof to remove deposits associated with ionization therefrom, the method comprising implanting the ion implantation system or One or more of its components are contacted with the BrF ₃ under conditions in which BrF ₃ is chemically reactive with the deposits to effect their at least partial removal.

In another aspect, the present invention is directed to a method of cleaning a pre-stage conduit of an ion implantation system for removing a deposit associated with ionization therefrom, the method comprising implanting an ion into the front of the system The stage conduit is contacted with a purge gas under conditions in which the purge gas is chemically reactive with the deposit to at least partially remove them. This method can improve the performance of an ion implantation system and extend its life.

In another aspect, the present invention is directed to a method for improving the performance and extending the life of an ion implantation system, the method comprising performing the cathode with a gas mixture comprising at least one cleaning gas and at least one deposition gas. Contact, wherein the gas mixture balances the deposition of material on the cathode and the corrosion of the deposited material or other material from the cathode.

Other aspects, features, and embodiments of the invention will be apparent from the appended claims and appended claims.

This invention relates to apparatus and methods for monitoring, controlling, and cleaning semiconductor processing systems and/or components thereof, and to compositions for such cleaning.

In one aspect, the invention relates to the removal of deposits from components of the semiconductor processing system or semiconductor processing system, wherein the system or system component is contacted with a cleaning composition comprising a gas phase reactive material .

As used herein, the term "gas phase reactive material" is intended to be broadly interpreted to mean a material comprising: one or more halides and/or complexes (in gaseous or vapor form), the one or more compounds and / or ion and plasma forms of the complex, as well as elements and ions derived from the one or more compounds, one or more complexes, and ion and plasma forms. A gas phase reactive material as used in the broad operation of the present invention may also refer to, but is not limited to, a "gas phase reactive composition", a "cleaning agent", a "cleaning gas", An "etching gas", a "gaseous halide", a "gaseous cleaning agent", a "reactive halide", a "cleaning compound", a "cleaning composition", a "cleaning vapor", and an "etching" Vapor" or any combination of such terms.

As used herein, in the case of an ion implanter, the "ion source region" includes, but is not limited to, a vacuum chamber, a source arc chamber, a source insulator, an extraction electrode, a suppression electrode, a high voltage insulator, a source sleeve, a filament, Cathode and reflector electrode. As will be understood by those skilled in the art, the term "ion source region" is used in its broadest sense. For example, a Bernas or Freeman ion source assembly includes a filament and a reflector electrode, and IHC. The source assembly includes a cathode and a counter cathode.

The present invention contemplates cleaning of semiconductor processing systems and components thereof, as well as other substrates and devices that are susceptible to deposits formed thereon during their normal processing operations. This operation includes, but is not limited to, vacuum pre-stage piping and low vacuum pump cleaning. In view of the description herein, as will be understood by those skilled in the art, the purge gas may flow through selected ports of the plurality of ports to bypass certain zones of the implanter and/or target specific zones. For example, XeF ₂ or other purge gas can be delivered through a port that is close to the zone in need of cleaning. Cleaning performance can also be enhanced as long as most of the purge gas will be introduced into the target zone along the flow path and will not be depleted by reaction with the residue (as may occur, for example, if the purge gas is only introduced through the ion source chamber) ). The selected port may be pre-existing or formed/produced for this purpose. This technique can be used to clean (but not limit) the ion source region of the implanter, the magnetic/analyzer region, the vacuum system, the processing chamber, and the like. Cleaning can be accomplished by continuously flowing a cleaning gas through and/or through a desired zone or region of the implanter for a predetermined amount of time. Alternatively, or in combination, the purge gas can be enclosed in the system for a predetermined amount of time to allow the purge gas to diffuse and react with unwanted residues and/or deposits.

The present invention provides an ion implantation system in a different aspect, the system having the ability to grow/etch a filament within the ion source of the arc chamber by appropriately controlling the temperature in the arc chamber to achieve the desired The growth of the filaments or the etching of the alternative filaments.

Additional aspects of the invention relate to the use of reactive gases such as WF _x , AsF _x , PF _x and TaF _x (where x has a stoichiometrically appropriate value or range of values) for in situ or separation In the cleaning arrangement of the bit, the area of the ion implanter or the components of the ion implanter are cleaned under plasma or high temperature conditions.

Another aspect of the invention relates to the use of BrF ₃ for cleaning an ion implantation system or one or more components thereof under ambient temperature, high temperature or plasma conditions in an in situ or off-site cleaning arrangement. .

The operation of an ion implantation system results in the deposition of materials associated with ionization in the system or its components. The present invention contemplates monitoring, controlling, and/or cleaning the ion implantation system and/or one or more components thereof to at least partially remove such ionization-related deposits from the system and/or components thereof. . The cleaning method relates to contacting the system and/or its components with a cleaning composition comprising a gas phase reactive material under conditions capable of reacting the gas phase reactive material with the deposit to achieve at least a portion thereof. Removal.

In addition to deposits associated with ionization caused by the feed gas itself, it has been discovered that deposits or residues formed within an ion implantation system may result from reactivity of the feed gas with the materials that make up the components of the system. . For example, the vacuum chamber of an ion implantation system can be constructed using stainless steel or aluminum. System components in the vacuum chamber may use graphite (eg, standard or vitreous), insulating materials (eg, boron nitride), and/or sealing materials (eg, Teflon) ^{, Kel-F TM, PEEK TM} , Delrin TM, Vespel TM, Viton TM, Buna-N, Si, etc.) to construct. Other materials that may be present in the ion implantation system and that are susceptible to chemical reactions generated by the deposit include, but are not limited to, ceramics, lead oxide containing epoxy compositions, aluminum nitride, aluminum oxide, cerium oxide, and the like. Boron nitride.

The ion source itself may be composed of tungsten, graphite, molybdenum or niobium, sometimes with a small amount of copper and silver. The ion source arc chamber is typically constructed of tungsten or molybdenum or a graphite body lined with tungsten or molybdenum. In this case, a fluoride source feed material (eg, BF ₃ , GeF ₄ , SiF ₄ , AsF ₅ , AsF ₃ , PF ₅ , and/or PF ₃ ) is at the operating temperature and the material of the arc chamber ( For example, tungsten or molybdenum from the arc chamber or the lining of the chamber is reacted to form an intermediate by-product which in turn can migrate and decompose in the system to deposit tungsten or molybdenum and release fluorine.

For example, a raw material gas such as GeF ₄ and dissociates generated in the ion source chamber will be free fluoride material of the arc chamber in the etching corrosion, such as tungsten. This reaction will occur on a colder surface, so if the plasma strikes and therefore the filament is hot, the fluoride will react with the tungsten on the walls of the arc chamber. The walls are etched and a WF ₆ gas is formed. WF ₆ then deposits tungsten on the hot filament causing its size to grow.

When GeF ₄ produces a large amount of free fluorine, the source gas such as BF ₃ or SiF ₄ produces a smaller amount of free fluorine and correspondingly a lesser degree of tungsten deposition on the filament, which, although small, is still important.

The fluorine source gas (e.g., PH ₃ and AsH ₃₎ based problematic, because it may cause deposition of the metal onto the walls of the arc chamber on the filament, the tapered filament results.

The present invention therefore contemplates cleaning an ion implantation system or one or more components thereof for at least partially removing the same ionization-related deposits as the material of the arc chamber.

The cleaning according to the present invention can be carried out in an ion implantation system in which a plurality of material gases are simultaneously introduced into the system. The feed gas may also be used in conjunction with one or more gas phase reactive materials, or may be alternately pulsed into the system with one or more gas phase reactive materials.

The ionization-related deposits referred to by the cleaning method of the present invention include a variety of materials that can interfere with the normal operation of the ion implantation system, for example, by being formed and accumulated in equipment of an ion source or other ionization process. The deposited material may comprise, consist of, or consist essentially of: bismuth, boron, phosphorus, antimony, arsenic, tungsten, molybdenum, selenium, tellurium, indium, carbon, aluminum, and/or antimony.

Deposits associated with ionization in the ion source arc chamber and on the extraction electrode can form flakes and form small particles. Once formed, the particles can be delivered by an ion beam, such as a beam of doped ions implanted into a wafer. If such transport particles reach the wafer, particle contamination generated on the wafer can severely reduce the yield of useful devices that can be fabricated on the wafer. The cleaning method of the present invention removes such deposits associated with ionization prior to their ability to form flakes and particles, and thereby achieves reduction in particles on the product wafer and increases the yield of the semiconductor device.

The gas phase reactive material or purge gas for cleaning according to the present invention may comprise any material effective to at least partially remove the ionization-related deposits in the ion implantation system.

The present invention also contemplates the use of gas phase reactive materials to remove deposits associated with ionization from undesired locations by appropriate control of the reaction, and/or to deposit materials at desired locations. In a particular embodiment of the invention, tungsten constitutes a material that is removed as an undesired deposit, while in other embodiments, tungsten is desirably deposited on a surface that benefits from its presence. Therefore, a gas (for example, XeF ₂ , GeF ₄ , SiF ₄ , BF ₃ , AsF ₅ , AsF ₃ , PF ₅ , and/or PF ₃ ) of the formally formed tungsten fluoride intermediate can be used in the present invention. Control and cleaning methods. In addition, various tungsten fluoride gases such as WF ₆ , WF ₅ , and/or WF ₄ can be directly used in the control and cleaning methods of the present invention. Thus, the gas phase reactive materials of the present invention include, but are not limited to, XeF ₂ , GeF ₄ , SiF ₄ , BF ₃ , AsF ₅ , AsF ₃ , PF ₅ , PF ₃ , F ₂ , TaF ₃ , TaF ₅ , WF ₆ , WF ₅ , and / or WF ₄ .

In various particular embodiments, the gas phase reactive material can be co-administered with a "cleaning enhancer" or "co-reactant" that increases the volatility of the gas phase reactive material, resulting in a cleaner than the use of no cleaning enhancer. Or the removal of more deposits of the gas phase reactive material of the co-reactant. For example, removal of tantalum deposits with XeF ₂ can be enhanced by the co-administration of Lewis bases and electronic feedback bond species. In certain applications, carbon monoxide, trifluorophosphine, and trialkylphosphines can be used.

As a further example, in an ion implantation system, wherein the feed gas is ionized into a continuous plasma in an arc chamber having a tungsten wall, on which one filament is mounted on one side and the other side is mounted There is a reflector and they are separated from the walls by ceramic insulators, which may be contaminated by decomposition products of the feed gas, elements of the arc chamber, and carbon.

In this case, a cleaning agent (e.g., XeF ₂ ) having a metal contaminant (e.g., tungsten) for removing volatile fluoride formation may be combined with an oxygen-containing additive by contaminating the oxygen-containing additive. The carbon is converted to CO, CO ₂ , and/or COF ₂ to effectively remove it. Oxygen-containing additive component is useful for this purpose in the particular embodiment of the present invention include, but are not limited to _{NO, N 2 O, NO 2} , CO 2 and /, or O _2.

The present invention therefore contemplates a cleaning agent comprising an effective removal of a metal contaminant (a volatile (gaseous) fluoride compound formed by the reaction to form a metal) and effective removal of carbon contaminants (by forming a A cleaning composition for both detergents of volatile oxides or oxyfluorides. The cleaning reagents can flow into the arc chamber simultaneously or sequentially.

In one embodiment, the reagents simultaneously flow into the arc chamber under ionization conditions such that the cleaning agents are ionized to convert metal and carbon contaminants from the chamber by mechanically A volatile compound that is easily removed by aspiration.

The conditions capable of reacting the gas phase reactive material with the deposit may include any suitable conditions of temperature, pressure, flow rate, composition, etc. under which the gas phase reactive material is contacted with the contaminant and chemically Interactions to remove such materials from the substrate, such as the surface of an implanted device that is contaminated with deposited material.

Examples of different conditions that may be used include, but are not limited to, ambient temperature, temperature above ambient temperature, presence of plasma, no plasma, subatmospheric pressure, atmospheric pressure, and superatmospheric pressure.

The exact temperature at which the contact for the gas phase reactive material is removed to remove deposits can range from about 0 °C to about 2000 °C in various embodiments. Contacting can include the gas phase reactive material being delivered in a carrier gas, or in a pure form, or in a mixture with an additional cleaning agent, dopant, or the like. The gas phase reactive material can be heated to chemically react with deposits at ambient temperature to increase reaction kinetics.

The reaction between the gas phase reactive material and the contaminant deposit can be monitored and/or adjusted based on changing the reaction characteristics between the cleaning agent and the contaminant. Such reaction characteristics may include pressure, time, temperature, concentration, presence of a particular substance, rate of pressure change, rate of change of a particular species concentration, change in current, and the like. Thus, introduction of the gas phase reactive material into the system can be terminated based on the achievement of a predetermined reaction characteristic, such as a predetermined voltage in the vacuum chamber, a predetermined amount of time, or a predetermined temperature, at The concentration of a particular element in the system, the presence of a particular by-product, the reaction product or other species in the system, or the achievement of a predetermined current condition in the monitoring operation.

The tungsten deposit can be caused by the reaction of the feed gas with the arc chamber of an implanter system. The method used to clean such deposits may depend on the temperature gradient of the system and/or the current flowing to and through the filaments, and/or any other characteristics that are effectively determined and can be monitored.

For example, fluorine from the feed material can be reacted with the arc chamber at a first temperature to form WF ₆ by the following reaction (1) or (2):

3F ₂ (g)+W(s)→WF ₆ (g) (1)

6F(g)+W(s)→WF ₆ (g) (2)

There may also be a reaction between the purge gas and the tungsten material of the arc chamber, for example:

3XeF ₂ +W → 3Xe+WF ₆ (3)

Alternatively, WF ₆ (or WF ₅ or WF ₄ ) can be provided directly to the system.

The tungsten fluoride that was formed or otherwise present in the system can then migrate to another location in the system. Depending on the temperature at other locations, the tungsten fluoride will etch or deposit tungsten at this location. At this filament, the temperature will primarily depend on the actual current flux through it. The temperature at other locations of the arc chamber can vary depending on the particular location and design of the arc chamber, filament current, along with other non-filament currents.

If the second position is at a high temperature, the tungsten fluoride decomposes, tungsten is deposited and fluorine is released, and as long as the tungsten fluoride continues to exist, the size of the tungsten deposit grows. The deposition reaction may include the following reactions (4), (5), and/or (6):

WF ₆ →W+3F ₂ (4)

2WF ₅ →2W+5F ₂ (5)

WF ₄ →W+2F ₂ (6)

Conversely, if the second location is at a moderate temperature, the tungsten fluoride can etch the location, remove the tungsten and retain fluorine in the reaction product such that the etched position shrinks as the etch proceeds. This etching reaction may include the following reactions (7), (8), and/or (9):

WF ₆ (g)+2W(s)→3WF ₂ (g) (7)

2WF ₆ (g)+W(s)→3WF ₄ (g) (8)

5WF ₆ (g)+W(s)→6WF ₅ (g) (9)

Thus, for the removal of tungsten deposits, the temperature of the component with the deposit can be selected to maximize the speed and extent of removal.

In other embodiments of the invention, the boron and/or molybdenum deposits are removed in a corresponding manner in the arc chamber.

In the method of the present invention, the contact of the cleaning agent with the processing equipment can be performed by monitoring the change in pressure during the contact, and when the pressure changes to zero, the contact is terminated.

Alternatively, the contacting can be carried out by monitoring the gas phase reactive material or the reactant obtained thereby, or the partial pressure of the reaction product produced in the contact, when the partial pressure reaches a predetermined value, ie, At the end of the journey, the contact is terminated. For example, such an end point monitoring can be performed using a suitable end point monitor, such as described in more detail in U.S. Patent No. 6,534,007, and U.S. Patent Application Serial Nos. 10/273,036, 10/784,606, 10/784,750, and 10/758,825. One type of endpoint monitor, or a thermopile infrared (TPIR) or other infrared detector.

In another embodiment, the contacting can be performed using controlled flow of the gas phase reactive material using the components of the processing equipment system, the components permitting adjustment of the partial pressure of the gas phase reactive material and thus controlling the reaction rate .

In yet another embodiment, the cleaning operation is performed using a continuous flow of a gas reactive material at a predetermined flow rate.

As discussed above with respect to reactions (1)-(9), deposits of tungsten associated with ionization can be deposited at very high temperatures and etched at low to moderate temperatures. In this regard, deposits associated with ionization mean deposits that are attributed to the plasma but are not necessarily due to the operation of the ions. Thus, as long as there is still a sufficiently hot surface, the deposition of tungsten can also occur without plasma (eg, the absence of ions). In the case where the deposited or etched location is the filament of the implant system, the temperature and current flux are directly related to each other. When the filament is etched, the filament will become thinner and the resistance to current will increase as the cross section of the filament decreases, so that the current flow through the filament will decrease. If the condition of the filament promotes deposition above it, the resistance to current will decrease with constant deposition as the cross section of the filament increases and the filament becomes thicker, correspondingly the current flow therethrough There has also been an increase.

In another aspect, the present invention is directed to a method of monitoring deposition on a source filament and resulting filament growth for monitoring current flow through the filament. Because, due to the deposition, the cross section of the filament is increased, the resistance to the current is reduced and the current is increased to maintain the filament at the temperature required to support the plasma in the arc chamber. Thus a monitored increase in current can be used to indicate a need for filament cleaning.

In another aspect, the present invention is directed to a method of etching or cleaning an etch of the filament by monitoring the flow of current through the filament. Because, due to etching, sputtering or evaporation, the filament cross section is reduced, the resistance to current is increased and the current is reduced to maintain the filament at the temperature required to support the plasma in the arc chamber. Thus a monitored reduction in this current can be used to indicate the need to deposit additional material onto an etched filament or to terminate a cleaning or ionization process.

Another embodiment of the invention includes a method of controlling the state of the filament based on monitoring the current flowing through the filament as detailed above.

In one embodiment, the decrease in the monitored filament current provides an indication that the filament is near the fracture, in response, a gas phase reactive material flows into the system (eg, when striking the plasma, or alternatively The plasma is turned off but the filament is still hot (e.g., ~2000 °C)) to induce a reaction that produces a deposit of metal on the filament, such as tungsten from the wall of the arc chamber. This reaction may be allowed to proceed until the current is within a predetermined range of effective operation of the ion implantation system indicating that the filament has "regenerated" to a satisfactory extent.

In another embodiment, the increase in the monitored filament current provides an indication that the filament is being grown due to the deposition of the material. In response, the gas phase reactive material flows into the system after allowing the filament to cool for a predetermined period of time, or to a predetermined temperature (which may be, for example, from room temperature to up to about 2000 ° C). Thus, the filament is cooled enough to allow etching of the filament. Thereafter, the subsequent etching reaction of the gas phase reactive material as a medium can thereafter be allowed to proceed until the current is within a predetermined range of effective operation of the ion implantation system, indicating that the filament has been tapered to an appropriate extent .

Thus, the method of the present invention can remove a deposit from the substrate by contacting a substrate with a gas phase reactive material sufficient to at least partially remove deposits from the substrate, the deposit comprising boron, antimony, arsenic. At least one of phosphorus, antimony, tungsten, molybdenum, selenium, tellurium, indium, antimony, and carbon. The gas phase reactive material used for this purpose may include one or more of the following materials: XeF ₂ , XeF ₄ , XeF ₆ , GeF ₄ , SiF ₄ , BF ₃ , AsF ₅ , AsF ₃ , PF ₅ , PF ₃ , F ₂ , TaF ₃ , TaF ₅ , WF ₆ , WF ₅ , WF ₄ , NF ₃ , IF ₅ , IF ₇ , KrF ₂ , SF ₆ , C ₂ F ₆ , CF ₄ , Cl ₂ , HCl, ClF ₃ , ClO ₂ , N ₂ F ₄ , N ₂ F ₂ , N ₃ F, NFH ₂ , NH ₂ F, HOBr, Br ₂ , BrF ₃ , C ₃ F ₈ , C ₄ F ₈ , C ₅ F ₈ , CHF ₃ , CH ₂ F ₂ , CH ₃ F, COF ₂ , HF, C ₂ HF ₅ , C ₂ H ₂ F ₄ , C ₂ H ₃ F ₃ , C ₂ H ₄ F ₂ , C ₂ H ₅ F, C ₃ F ₆ , COCl ₂ , CCl ₄ , CHCl ₃ , CH ₂ Cl ₂ , and CH ₃ Cl.

In the practice of the present invention, the fluorinated ruthenium compound can be used as a cleaning agent as well as a plasma source reagent, and can include any suitable number of fluorine atoms. A higher ratio of F to Xe allows for relatively faster and more efficient cleaning than lower F/Xe compounds. Higher vapor pressures increase the delivery rate of the cleaning agent and enable it to deliver more material.

In one embodiment of the invention, antimony hexafluoride is used as a cleaning or plasma source reagent. Although the vapor pressure of XeF ₆ is about seven times higher than the vapor pressure of XeF ₂ at room temperature, XeF ₆ and XeF ₄ are very reactive with water. XeF _{6 is} most advantageously used in a cleaning environment that is not related to the presence or formation of water, hydrocarbons, hydrogen or reducing agents. However, when using a cleaning compound having a lower vapor pressure, it may be necessary to adjust the flow line to avoid undue pressure drop in the flow path and maintain a suitably high delivery rate of the cleaning agent.

The apparatus for carrying out the method of the present invention can be constructed and arranged in any suitable manner to provide a gas phase reactive material to the cleaning.

In one embodiment, the present invention provides an ion implantation and cleaning assembly comprising: (i) an ion implantation system comprising one or more components during ion implantation processing of the system Deposits associated with ionization are accumulated on the components, (ii) a cleaning assembly comprising a source of cleaning composition comprising a cleaning composition comprising a gas phase reactive material, such as a halogenation a compound that is reactive with the deposit to effect at least partial removal of deposits from one or more components under cleaning conditions, the cleaning conditions comprising contact of the cleaning composition with the deposit, (iii) a flow line adapted to transfer the cleaning composition from the source of the cleaning composition to one or more components for contacting it under cleaning conditions, and (iv) a flow-through member adapted to control the process in the cleaning state The intermediate cleaning composition flows through the flow line to effect at least partial removal of deposits from one or more components.

The flow-through components in the above assemblies may be of any suitable type including, for example, valves, valve actuators, flow restrictors, regulators, pumps, mass flow controllers, pressure gauges, residual gas analyzers, central processing units, diaphragms ,and many more. Such flow-through components are adapted to operate under the specific cleaning conditions employed.

One or more components in the implanter device (on which the components accumulate deposits associated with ionization during the ion implantation process in the system) may be of any suitable type, for example, vacuum Chambers, arc chambers, electrodes, filaments, high voltage bushings, electromagnetic waveguides, wafer processing components, clamp rings, wheels, discs, and the like. In one embodiment, the component is a vacuum chamber or a component contained therein.

The cleaning composition source can comprise a material storage and dispensing kit containing the cleaning composition. The material storage and dispensing kit includes a container that can be, for example, a generally cylindrical container defining an inner volume thereof. In a particular embodiment, the cleaning composition can be solid at ambient temperature and the cleaning composition can be supported on a reinforced surface area within the container. The reinforced surface area can include a structure therein, such as a tray, as described in U.S. Patent No. 6,921,062, or a porous inert foam, such as anodized aluminum, stainless steel, nickel, bronze, etc. to provide the A consistent evaporation rate of the cleaning material and, in turn, a vapor pressure sufficient to effect the dispensing of the associated cleaning process and the ionization step. In the case of a tray, in a dispensing operation, the cleaning composition can be supported by a number of tray surfaces having flow channel tubes associated therewith for vapor to flow upwardly into the dispensing opening in the container.

The flow line in the above-described equipment arrangement is adapted to transfer the cleaning composition from the source of the cleaning composition to the arc chamber under cleaning conditions. This adaptation can be based on different characteristics of the cleaning composition. For example, when the cleaning composition has a low vapor pressure, high conductivity can be used to avoid unnecessary pressure drops in the flow path. Methods for maximizing conductance and minimizing flow compression are well known in the art.

In all of the cleaning methods of the present invention, cleaning may optionally be performed by additional methods and apparatus to extend the life of the ion implantation system, particularly the ion source. Such methods of extending life may include altering an ion implantation system to accommodate a particular substrate, deposited material, and/or gas phase reactive material. Variations in system equipment may include, but are not limited to, providing the following: an extraction electrode with an active thermal control system; a frequency of reduced discharge/actively heated extraction electrode; a metal comprising preferably aluminum, molybdenum or oxidation Aluminum (Al ₂ O ₃ ) extraction electrode; remote plasma source; extraction electrode and heater association; extraction electrode and cooling device correlation; smooth featureless extraction electrode; plasma chamber, the same The slurry chamber is arranged to receive a plurality of source gases that are capable of being decomposed by the plasma to produce a stream of reactive gases passing through the outlet of the chamber and the conduit to deliver the reactive gas to the ionization chamber; Detectors, the temperature detectors being designed to detect the substantial end of the exothermic reaction of the reactive gas with the contamination on the surface of the processing system; components of the processing equipment susceptible to damage by the gas phase reactive material Protection (for example, providing a shield against such materials around parts susceptible to gas-phase reactive materials); and/or containing aluminum Alumina parts of the system.

Methods of extending the life of the processing equipment may include, but are not limited to, actively heating the extraction electrode to reduce the frequency and occurrence of the discharge; heating the extraction electrode above the condensation temperature of the source material delivered to the ion source; actively controlling the fit The temperature of the extraction electrode of the particular type of ion source used (eg, in combination with a heated or cooled ion source to heat or cool the electrode); and/or to maintain the extraction electrode at elevated temperatures during the extraction process. The alterations and methods of such additional devices are more fully described in U.S. Patent Application Publication Nos. 2006/0272776 and 2006/0272775, and International Patent Publication No. WO 05/059942, which is incorporated herein in its entirety by reference.

In a particular embodiment, the ion implantation system includes an arc chamber and a dopant source, wherein the dopant source can include, for example, BF ₃ , XeF ₂ , AsH ₃ , PH ₃ , GeF ₄ , SiF ₄ , H ₂ Se, AsF ₅ , AsF ₃ , PF ₅ , PF ₃ or other dopant sources of boron, antimony, arsenic, phosphorus or antimony.

In another embodiment, the present invention is directed to a method for ion implantation, the method comprising: generating a plasma from a dopant source gas in an arc chamber of an ion implantation system, the dopant source Gas flows through the arc chamber to form dopant source ions for implantation, wherein the gas phase reactive material is doped during at least a portion of the time during which the dopant source gas flows through the arc chamber The dopant source gas flows in parallel through the arc chamber to effect cleaning in the ion implantation system.

In general, although the dopant source gas and the gas phase reactive material can be flowed in parallel for in situ cleaning, it is typically preferred to perform the cleaning operation in a sequential manner, such as when the ion source is from a first blend The dopant source generates a first plasma, and then the ion source generates a second plasma from a second dopant source, using an intervening cleaning step, wherein the gas phase reactive material flows through the ion source, With or without plasma generation.

In one embodiment, the present invention provides a method of forming a doped germanium substrate, the method comprising implanting Xe ⁺ ions into a germanium substrate, and thereafter implanting dopant ions in the germanium substrate. In this process, Xe ⁺ ions are implanted for amorphizing the crystal structure of the substrate.

In the formation of fluorinated tantalum plasma (eg, XeF ₂ plasma) for cleaning, the Xe ⁺ ions can be subjected to low energy sputtering cleaning of some of the sources themselves. After extraction, Xe ⁺ ions can perform some high-energy sputtering of downstream components of the ion source, such as vacuum walls, ion optics, wafer pads, and wafer holders.

Similarly, in the case of tungsten fluoride species, such as WF ₆ , WF ₅ , and/or WF ₄ , free fluoride can be sputtered with clean, different ion source components and/or tungsten can be deposited on the ion source. On different parts. The behavior that occurs between cleaning and deposition depends on the temperature of the various components in the system.

The present invention is directed to a method and apparatus for cleaning an ion source region of an ion implantation system for use in the fabrication of a microelectronic device. The ion source region can include, for example, an indirectly heated cathode source, a Freeman source or a Bernas source.

In one embodiment, the present invention relates to the use of the vacuum chamber and/or component and a gas phase reactive halide composition from the ion implanter and the components contained therein in sufficient time and under sufficient conditions. Contacting to remove residue in situ to at least partially remove residue from the vacuum chamber and/or component, and relating to the completion by such a manner that when the residue and the vacuum chamber are constructed and/or When the materials of the components are different, the gas phase reactive material selectively reacts with the residue and reacts minimally with the material of the vacuum chamber and/or component constituting the ion implanter (eg, substantially non-reactive, and Preferably, the reaction is completely non-reactive; and when the residue is the same as the material constituting the vacuum chamber and/or the component, the gas phase reactive material may be reactive with the residue and the vacuum chamber and/or the component.

As used herein, the term "selectively" applied to the reactivity of the gas phase reactive halide with a residue is used to describe a preferential reaction between the gas phase reactive halide and a residue. . Although substantially non-reactive with the material of the vacuum chamber and/or component that constitutes the ion implanter, if the vacuum chamber and/or component contains the same or similar elements as those residues, the gas phase reactive halide can Certain materials that make up the vacuum chamber and/or components of the ion implanter react. For example, when selectively reacting with tungsten deposits from a component and removing them, the gas phase reactive material may also react with tungsten in the component itself. For this co-reaction to occur, the residue and components need not be exactly the same material, but will contain some common materials.

In another embodiment, the ion implanter components are cleaned off-position in a separate specialized chamber into which the components are moved from an ion implanter.

Further consideration is given in situ to cleaning, which depends primarily on three factors: the nature of the reactivity of the cleaning precursor, the volatility of the by-products of the cleaning reaction, and the reaction conditions used in the chemical cleaning. The cleaning composition must remove unnecessary residue while minimizing wear of the materials that make up the ion implanter. The by-products produced by the cleaning reaction must be sufficiently volatile to facilitate their removal by the vacuum system of the ion implanter or other suction means.

Cleaning of the residue formed from the same material as one or more components of the ion implanter can result in some wear of the component itself. Specifically, the removal of tungsten deposits from a system utilizing a tungsten arc chamber using XeF ₂ as a cleaning agent results in the removal of certain tungsten from the interior of the arc chamber. However, in order to maximize system efficiency, the loss of certain internal materials of the arc chamber is not critical from the standpoint of system performance degradation (if the system is not cleaned and tungsten deposits are allowed to accumulate in the system).

The gas phase reactive material may comprise, for example, a fluorinated hydrazine compound vapor, such as XeF ₂ vapor. XeF ₂ is a preferred reactive halide gas and will sublime at room temperature, but can be heated using a heater to increase the rate of sublimation. XeF ₂ is known to be an effective tantalum etchant and has been used as a selective etchant in microelectromechanical systems (MEMS) device processing. Specifically, XeF ₂ reacts with hydrazine according to the following reaction.

2 XeF ₂ (g)+Si(s)→2 Xe(g)+SiF ₄ (g) (10)

The 矽/XeF ₂ reaction can occur without activation, i.e., without plasma or heat. The reaction rate of XeF ₂ with Si is much higher than the reaction rate of XeF ₂ with SiO ₂ such that XeF ₂ selectively reacts with Si.

XeF ₂ or other fluorinated ruthenium compounds are usefully useful in the practice of the present invention as an etchant for metal boron. Although not wishing to be bound by theory, it is believed that boron is etched according to the following reaction (11):

3 XeF ₂ (g)+2 B(s)→3 Xe(g)+2 BF ₃ (g) (11)

The present invention contemplates the use of XeF ₂ as an etchant for arsenic, phosphorus, and antimony, and may be related to the following reactions:

5 XeF ₂ (g)+2 As(s)→5 Xe(g)+2 AsF ₅ (g) (12)

5 XeF ₂ (g)+2 P(s)→5 Xe(g)+2 PF ₅ (g) (13)

2 XeF ₂ (g)+Ge(s)→2 Xe(g)+GeF ₄ (g) (14)

Such reactions can be carried out with or without high energy activation.

When the residue material is different from those materials, the method and apparatus of the present invention are used to at least partially remove residue from the components of the ion implanter, for example, removing at least 25%, more preferably at least 50% and most preferably At least 75% of such residue, and is accomplished by means of materials constituting the components of the ion implanter, such as aluminum, tungsten, molybdenum, graphite, insulating materials, sealant materials, etc., on residues Perform selective removal.

When the residue is the same material as the material constituting the component, it is desirable to have a similar degree of residue removal while maintaining the removal of the material from the component to a low extent, such as in the range of microns or tens of microns, so that Does not significantly affect the performance of the part. In addition, since the deposits generally do not have a uniform thickness or deposition, they may be more reactive during the cleaning process than the material of the component itself, such that the gas phase reactive material composition more selectively reacts with the component portion. The residue is reacted.

The gas phase reactive material composition can be delivered in several forms to the ion source region where in situ cleaning is possible, including a non-flowing manner, a continuous manner, and a direct introduction. Such cleaning methods are more fully described in International Publication WO 07/127865, along with apparatus and methodology that are effectively used in the operation of the present invention. The disclosure of International Publication No. WO 07/127865 is incorporated herein by reference in its entirety. Although the use of XeF ₂ as a cleaning composition is described herein in connection with various embodiments of the present invention, it is to be understood that other fluorinated compounds such as WF ₆ , WF ₅ , and/or WF ₄ may be used instead or In combination with XeF ₂ , other and additional fluorinated compounds may be used. For example, BrF ₃ can be used to etch tungsten without the need for plasma. In another aspect, the present invention is directed to a method for improving the performance and extending the lifetime of an ion implantation system using a solid doped material, the method comprising using XeF ₂ or N ₂ F ₄ as the solid doping A carrier gas of the material. The solid doping materials include, but are not limited to, the elements arsenic, phosphorus, selenium, tellurium, SbF ₃ , InCl, SeO ₂ , Sb ₂ O _{3 ,} and InCl ₃ . As contemplated by the present invention, a carrier gas using XeF ₂ or N ₂ F ₄ as Sb ₂ O ₃ , InCl ₃ or other solid doping material removes Sb, In deposited on the source chamber and its components, and Other dopants. This transient method has utility even if it is switched to boron after Sb implantation. The advantages obtained by this method are at least twofold: first, it provides an immediate source cleaning to prevent or reduce dopant buildup onto the ion source chamber and its components, thereby improving ion source performance while extending the ion source. Lifetime; second, it enhances and/or stabilizes the plasma and/or beam current.

In another aspect, the present invention is directed to a method for improving the performance and extending the life of an ion implantation system using a gaseous dopant material, the method comprising using XeF ₂ or N ₂ F ₄ as a gas blending with the gas A mixture of miscellaneous materials. The gaseous dopant materials include, but are not limited to, GeH ₄ and BF ₃ . As contemplated by the present invention, the use of XeF ₂ or N ₂ F ₄ as a co-current gas with GeH ₄ or other gaseous dopant material removes Ge or other dopants deposited on the source chamber and its components. The advantages obtained by this operation of the present invention are at least twofold: first, it provides immediate source cleaning to prevent or reduce dopant buildup onto the ion source chamber and its components, thereby improving ion source performance. And extend the life of the ion source; second, it enhances and/or stabilizes the plasma and/or beam current.

In another aspect, the present invention is directed to a method of cleaning a pre-stage conduit of an ion implantation system for removing deposits associated with ionization herein, comprising implanting a pre-stage of an ion implantation system with A purge gas is contacted under reaction conditions wherein the purge gas is chemically reactive with the deposit to effect at least partial removal therein. Deposits include, but are not limited to, those including B, Ge, Si, P, and As, or mixtures thereof. The purge gas includes, but is not limited to, XeF ₂ , N ₂ F ₄ , F ₂ , and other fluorinated materials that are reactive with a deposit of the foregoing composition. As will be understood by those skilled in the art, the amount of cleaning gas required will depend on the amount of deposit present. Similarly, the amount of heat released during the reaction of the purge gas with the deposit depends on the flow rate of the purge gas. The identification and concentration of by-product species generated from the cleaning process depends on the flow rate of the purge gas, the combined composition of the deposits, and the pump purge flow rate. For purposes of non-limiting illustration only, an example of the cleaning of phosphorus from a pre-stage pipe using XeF ₂ is illustrated below: a chemical reaction system for determining the amount of XeF ₂ required during the cleaning process: 5 XeF ₂ (g) +2 P(s) → 5 Xe(g) + 2 PF ₅ (g). The formation enthalpy (in kJ / mol) is derived from ^{Lange's Handbook of Chemistry (14 th} ed) and are listed here for determining the heat released during the _{reaction: XeF 2 (-164); Xe} (0); P (0); and PF ₅ (-1594.4). The flow rate of XeF ₂ determines the length of time required for the cleaning process along with the heat released. There is no means of heating the XeF ₂ cylinder, the maximum sustained flow rate is about 50 sccm, assuming sufficient delivery duct conductivity. If the cylinder is kept at room temperature by using a heating jacket, the flow rate can be increased to 100 sccm or more. The amount of XeF ₂ required to clean the phosphorus deposit is shown in Table 1, and the amount of heat released during the cleaning reaction is shown in Table 2.

The maximum production rates of the different by-products from the above cleaning reactions are shown in Table 3.

As will be understood by those skilled in the art, since the composition of the residues may vary, the data shown in Table 3 is based on the assumption that the amount of by-products is determined to assume 100% of that element for each element. Constitutive composition. In addition, the maximum concentration of such materials depends on the dilution flow rate in the exhaust system. For example, if the low vacuum pump has a 10 slpm nitrogen purge, then downstream of the pump, the maximum steady state concentration of PF ₃ is 3330 ppm. This value can be increased if the flow rate of XeF ₂ is greater than 50 sccm.

In an embodiment of the above method, the purge gas flows into the implant source chamber, the turbo pump is turned off and the low vacuum pump is turned on. This operation enhances the flow rate of the purge gas over the deposits of the foreline, thus providing a faster cleaning process. The rate of purge gas flow can be further heated by heating the gas cylinder in which the purge gas is stored at or above room temperature. Preferably, the delivery line from the gas cylinder to the ion implanter is similarly heated in this operation.

In another embodiment of the above method, the cleaning gas flows into the implant source chamber in a pulsed manner, wherein the implant source chamber, the pump, and the pre-stage tube are charged to a certain pressure and then pumped to a more Low pressure. This process is repeated until the deposit on the foreline of the ion implantation system is removed. This operation preferably uses an isolation valve on the inlet of the low vacuum pump.

In a preferred operation, the above embodiment further comprises heating the gas cylinder in which the cleaning gas is stored at room temperature or above.

For all embodiments, the method preferably further comprises a gas scrubber on the outlet of the low vacuum pump to remove the volatile byproducts produced from the cleaning process.

Each embodiment preferably further comprises a Xe recovery system as commercially available from Air Products and Chemicals, Inc. (PA, USA) and is described at http://www.fabtech.org/product_briefings/_a/new_product_air_products_offers_on_site_xenon_recovery. It is incorporated herein.

Another embodiment of a method of cleaning a pre-stage conduit of an ion implantation system includes providing the purge gas downstream of a turbo pump and continuously flowing the purge gas through a pre-stage conduit of the ion implantation system. The continuous flow of purge gas can be directed to the source shell, the region between the source shell and the source turbine pump, or downstream of the source turbine pump. This operation preferably cleans deposits on the foreline tube (even when the implantation process is performed), thereby reducing disruption of the ion implantation operation.

In the above embodiment, the purge gas is preferably stored in a gas cylinder; the method preferably further comprises heating the gas cylinder in which the purge gas is stored at or above room temperature.

The above embodiments preferably further comprise providing a gas scrubber at the outlet of the low vacuum pump to remove volatile by-products produced from the cleaning process.

The above embodiments further comprise providing a Xe recovery system as commercially available from Air Products and Chemicals, Inc. (PA, USA) and described at http://www.fabtech.org/product_briefings/_a/new_product_air_products_offers_on_site_xenon_recovery. It is incorporated herein.

In another aspect, the invention relates to a method for improving the performance and extending the life of an ion implantation system having a cathode, the method comprising the cathode and the at least one cleaning gas and the at least one deposition gas A gas mixture is contacted, wherein the gas mixture balances the deposition of material on the cathode from the stripping of the material or other material from the cathode. The purge gas of the gas mixture removes the dopant material deposited on the cathode and the material of the cathode, and the deposition gas of the gas mixture causes the dopant material to deposit directly or indirectly on the cathode. This gas mixture maintains a balance between the accumulation of dopant material on the cathode and the stripping of it or other materials, and thus extends the life of the ion source. It will be appreciated that not only can the dopant material be deposited or etched, but the material of the arc chamber wall (eg, W or Mo) can be deposited or etched. The purge gas prevents deposition or reduces the deposition rate either directly (via sputtering or chemical etching) or indirectly (via chemical degassing of tungsten fluoride/molybdenum fluoride). The deposition gas is circulated through the halogen (the fluorine from the gas etches W or Mo from the stave, and then the W or Mo is decomposed onto the very hot cathode), or by actually depositing dopant molecules/atoms on the cathode ( For example, B) from BF ₃ causes deposition on the cathode, and a similar mechanism is applied to the filament of the Bernard ion source. For dopant deposition conditions on insulators or other sensitive components of the arc chamber, the purge gas tends to chemically etch the formed dopant deposits, or the purge gas can first react with the deposition gas before the dopant is deposited to prevent Or minimize deposition. By way of example, how the cleaning gas can prevent deposition in the first case: the deposition gas GeH ₄ can form Ge deposits on the cathode, insulator or other components. If the purge gas is XeF ₂ , it can react with GeH ₄ to form at least some amount of GeF ₂ and/or GeF ₄ that is more volatile than Ge, and thus can be removed from the source region via aspiration. Further, either or both of the deposition gas and the cleaning gas may be a dopant gas. The storage and distribution of the gas mixture in the ion source implanter can be accomplished by using an adsorption-desorption device (referred to as an SDS-safe delivery source) as described in U.S. Patent No. 5,518,528, The contents of which are incorporated herein by reference; a fluid storage and dispensing system (referred to as a VAC vacuum actuated gas cylinder) containing a container for maintaining a fluid at a desired pressure is described in U.S. Patent No. 6,101,816, and The contents of which are incorporated herein by reference; or a mixed fluid storage and distribution system of SDS and VAC (referred to as VAC-Sorb), which is described in U.S. Patent No. 6,089,027, the disclosure of which is incorporated herein by reference. Such fluid storage and distribution systems provide for delivery of gases at sub-atmospheric pressures and are thus safer and more efficient than high pressure fluid storage and distribution systems. In addition, some of the gases in the gas mixture can be stored and distributed together in an SDS, VAC, or VAC-Sorb system that is incompatible in the coexistence of high pressure fluid storage and distribution systems.

In one embodiment of the above method, the plurality of gases of the gas mixture flow simultaneously to contact the cathode or other sensitive components susceptible to deposition.

In another embodiment of the above method, the plurality of gases of the gas mixture sequentially flow to contact the cathode or other sensitive components susceptible to deposition.

In another embodiment of the above method, the gas mixture comprises a combination of at least one hydrogen-containing gas and at least one fluorine-containing gas, wherein the hydrogen-containing gas acts as a purge gas and the fluorine-containing gas acts as a deposition gas.

In another embodiment of the above method, the gas mixture comprises a combination of at least one non-doped gas (ie, a gas free of As, P, Ge, B, Si, or C) and at least one dopant gas, wherein The non-doped gas acts as a purge gas and the dopant gas acts as a deposition gas.

Examples of the cleaning gas are, but not limited to, Xe/H ₂ , Ar/H ₂ , Ne/H ₂ , Xe/NH ₃ , Ar/NH ₃ , Ne/NH ₃ , Ar/Xe, and Ar/Xe/H ₂ .

Examples of deposition gases are, but are not limited to, F ₂ , N ₂ F ₄ , ClF ₃ , WF ₆ , MoF ₆ , GeF _{4 ,} and NF ₃ .

Examples of gas mixtures are, but are not limited to, AsH ₃ /AsF ₃ , AsH ₃ /AsF ₅ , PH ₃ /PF ₃ , PH ₃ /PF ₅ , SiH ₄ /SiF ₄ , H ₂ /Xe/SiF ₄ , GeH ₄ /GeF ₄ , H ₂ /Xe/GeF ₄ , H ₂ /GeF ₄ , B ₂ H ₆ /BF ₃ , H ₂ /BF ₃ , F ₂ /BF ₃ , CO ₂ /F ₂ ,CO ₂ /CF ₄ , CO/F ₂ , CO/CF ₄ , COF ₂ /F ₂ , COF ₂ /CH ₄ , COF ₂ /H ₂ .

The features and advantages of the present invention are more fully shown by the following non-limiting examples.

Example 1

This example shows an improvement in ion source lifetime and utilization of the implanter, which can be achieved by using a chemical cleaner to remove deposits. Preferably, the deposits are removed at regular intervals to prevent accumulation of contaminant sheets and conductive membranes in the implanter.

In-situ cleaning system 0 by supply container at regular intervals from the ion implanter is located in the gas tank of the XeF ₂ to XeF _2, XeF ₂ wherein the vapor is washed twice for 10-15 min daily Introduced into the ion source. A high current implanter was used to test to assess the flow kinetics of the cleaning reagent. The XeF ₂ cleaning characteristics were determined and confirmed that the cleaning agent did not adversely affect the beam conduit components of the implanter. Thus, the cleaning process using the XeF ₂ reagent is acceptable for use in a moderate current implanter device.

Figure 1 is a graph of ion source lifetime data compiled by such a moderate current implanter before and after the in-situ cleaning process. These materials were developed for a doped composition comprising arsine and phosphine. Prior to cleaning, the ion source has an average operating life of approximately 250 ± 90 hours, limited by two common failure modes.

The main failure mode is an excessive leakage from a suppressor voltage supply. In order to successfully extract a stable ion beam, a suppressor voltage is applied to an electrode positioned outside the arc chamber. The electrodes are electrically isolated by a plurality of small insulators, and accumulation of a conductive film on one or more of the insulators may cause excessive suppressor leakage.

A second mode of failure is attributable to a short circuit of components in the arc chamber of the sheet of deposited material.

It was found that these failure modes can be minimized by a chemical cleaning process in situ. Regular daily cleaning twice increases the life of the source in production.

The effect of XeF ₂ on the leakage current of the suppressor is further illustrated in Figure 2, which is a graph of the leakage current for the medium current tool before and after the introduction of the in-situ cleaning operation. Each data point represents an average suppressor current during the time required to implant a wafer batch, and these points have been plotted along with the life of several ion sources. The amount of leakage depends on the elapsed time from the replacement of the last preventive maintenance insulator. These data show that periodic in-situ cleaning greatly reduces the leakage current so that it never reaches the upper control limit of 1.5 mA, at which point an unscheduled source maintenance is required.

The effect of in-situ cleaning was also evaluated using an implant doping mixture including BF ₃ and PH ₃ . The source is operated under such condition and a failure has occurred 497 hours in an arc constraints (based on tungsten or boron deposit on filament), which is attributable to the chemical properties of BF _3. The operating system is advantageous with respect to a single source life of 497 hours in the test system compared to a long-term historical average of 299 hours in the same system. This is a single data point, but it fits the model built. In this case, the improvement in source life appears to be due to the etching of tungsten deposits with XeF ₂ in the source arc chamber.

The photographs of Figures 3A and 3B provide additional evidence of the effectiveness of the cleaning agent. In both photographs, the appearance of the ion source shell after removal of the periodically preventatively maintained ion source assembly after approximately 98 days of production in each case is shown. For the photograph in Figure 3A, in-situ cleaning was performed twice daily, while for the photograph in Figure 3B, no cleaning was performed.

In the absence of cleaning, there is a substantial amount of deposited material, some of which have begun to delaminate and flake. Manual scrubbing is used to remove deposited material from the inner surface of the shell during regular maintenance activities. Cleaning the shell in situ looks cleaner and does not require less time or time for manual cleaning. The deposit exits the arc chamber by unreacted XeF _{2 and} passes to the wall of the vacuum chamber for removal, while dopants and other deposits are removed by chemical reaction.

Deposits in and around the ion source produce a so-called "implanter memory effect." When changing from one dopant source gas to another, ions from the first dopant element continue to be extracted from the ion source plasma long after the first dopant gas inflow ceases. This effect in some cases causes a serious contamination of the desired ion beam current and leads to a deterioration of the implantation process.

An example of the memory effect of the implanter is P contamination in a BF ₂ implant. The consequences of this pollution on process yields are so severe that many semiconductor manufacturing facilities are avoiding the implantation of phosphorus and boron onto the same tool. This is a substantial obstacle in scheduling implant operations. P / BF ₂ sediment pollution sources due to the phosphorus implanted in the PH _3. When the BF ₂ ⁺ implant was replaced with BF ₃ gas, some of the fluorine reacted to form ³¹ P ¹⁹ F ⁺ . The mass of ³¹ P ¹⁹ F ⁺ is 50. This is very close enough to the mass of 49 desired for ¹¹ B ¹⁹ F ₂ such that PF ^{+ is} co-implanted with BF ₂ ⁺ ions. Results based, BF ₂ ⁺ implantation in a specific mass by - an energy range having a certain high limiting current system mass resolving power of the minimum.

The XeF ₂ wash was evaluated using a P ⁺ ion beam from a PH ₃ doping gas using a high current implanter operating in simulated production for approximately 200 hours to determine its effect on the memory effect of the implanter. The system switches to BF ₃ gas and is implanted directly into a bare 矽 monitor wafer using a high dose (5 × 10 ¹⁵ ions/cm ² ) of BF ₂ ⁺ . In the BF ₂ ⁺ implantation process, resolving aperture analyzing magnet system is more open than usual to ensure that contamination effects on conventional measurement using secondary ion mass spectrometry (SIMS) analysis of sufficiently large.

The cleaning effect of BF ₃ , argon, and XeF ₂ was compared by operating each of the three gases and then periodically monitoring the amount of remaining contaminants by implanting the monitor wafer with BF ₂ ⁺ . The amount of P co-implanted with BF ₂ was measured by SIMS. Shows the implanted phosphorus SIMS spectrum of a typical Figure 4A, wherein the peak in the spectrum corresponding to the phosphorus extracted from the ion source PF ⁺ implantation depth of the ions, and the dose corresponds to approximately in BF ₂ A degree of contamination of 3% PF.

FIG. 4B system using XeF ₂ or BF ₃ as a view of a function of the degree of contamination of the cleaning time, wherein the transition from FIG PH ₃ into the BF ₃ immediately after the normalization (the normalize) the degree of contamination. When the BF ₃ plasma was operated, there was almost no effect on PF contamination even after 2 hours. Similar results were obtained when argon plasma was used (not shown). By comparison, PF contamination was reduced by a factor of two after in-situ washing with XeF _{2 for} only 15 minutes, and by a factor of five after in-situ washing with XeF _{2 for} 30 minutes.

Prior to in-situ cleaning, the medium-current implanter unit averaged 3.3 source changes per tool per month, with an average source replacement process and subsequent qualifying tests requiring approximately 5 hours, equivalent to nearly a loss of production time per tool per year. 200 hours. The source life is effectively doubled by in-situ cleaning, resulting in an additional production time of approximately 100 hours for each medium current tool. The savings from test wafers, along with the savings in metrology tools required for production time and post-processing of qualified wafers (up to 40 qualification tests per year for each medium current implanter), demonstrate the effectiveness of in-situ cleaning .

Example 2

This example demonstrates the control of filament growth in an ion source of an illustrative ion implanter system.

Figure 5A is a graph showing the effect of XeF ₂ flow and arc power variation with respect to increased filament current and weight. The graph shows a graph of filament weight (in grams) as a function of the elapsed time (in hours) of the implant system operation. The higher line in the figure represents a XeF ₂ flow of 2.2 standard cubic centimeters per minute (sccm) and an arc power of 100 volts / 0.05 amps, for which a 319 mg/hr wire was determined after 3 hours of operation. Extreme weight increases. The lower line in the figure reflects a 0.5 sccm XeF ₂ flow and a 40 volt/0.05 amp arc power which produces a filament weight gain of 63 mg/hr over a 3 hour continuous run time.

Figure 5B shows a graph of the effect of XeF ₂ flow and arc power changes in terms of filament current. The figure shows a plot of filament current (in amperes) as a function of the execution time of the implanter system. The higher line in the figure represents a XeF ₂ flow rate of 2.2 standard cubic centimeters per minute (sccm) and an arc power of 100 volts / 0.05 amps, for which an increase in filament current of 16 amps/hour is determined. The lower line in the figure reflects a XscF ₂ flow of 0.5 sccm and an arc power of 40 volts/0.05 amps, which produces a filament current increase of 2.3 amps/hour over a 3 hour continuous execution time.

Figure 6 is a graph of filament weight change (in milligrams per hour) as a function of average filament current (in amperes). The graph shows the effect of heat flow (no plasma) and plasma conditions on tungsten transport for hot wire conditions for low flow and high flow rates and for low flow and high flow plasma conditions. These materials show that the transport of tungsten in the system can be selectively adjusted by selecting appropriate processing conditions to achieve deposition of the material on the filament or alternative etching.

Example 3

This example shows an improvement in ion source lifetime and implanter utilization that can be achieved by monitoring the cathode bias power supply.

Figure 7 is a graph showing changes in cathode bias power as a function of time and gas type. Specifically, when the flow GeF _4, so that the halogen cycle W is deposited on the cathode, which causes increase in the bias power (ion beam current to maintain the settings). When PH ₃ flows, the phosphorus ions sputter the cathode, causing a drop in the cathode bias power. In this example, PH ₃ and GeF ₄ ratio of the bias power lines such that the final output reaches its maximum after about 76 hours. Monitoring the bias power in this manner, and taking appropriate action will improve the ion source lifetime.

Figure 8 is a graph showing the change in cathode W weight as a function of bias power. Specifically, using XeF ₂ as the source gas, tungsten (W) can be etched or deposited on the cathode from the cathode by simply changing the cathode bias power. The high bias power increases the temperature of the cathode to a degree that favors the W deposition reaction, while the low bias power to the medium bias power lowers the temperature to a condition that favors the W etch reaction. Depending on the state of the cathode, the bias power can be selected to etch unwanted deposits from the cathode, or to deposit the W back onto the cathode, and thus can improve ion source lifetime.

Although the present invention has been described with reference to various specific embodiments thereof, it should be understood that the invention is not limited thereto, and is intended to cover various other modifications and embodiments as would be understood by those skilled in the art. Therefore, the invention is intended to be broadly construed and construed in accordance with the appended claims.

Figure 1 is a graph of source life data before and after introduction of the in-situ cleaning process, showing the prolongation of life due to the process.

Figure 2 is a graph showing the effect of XeF ₂ on the leakage current of the suppressor, as detailed in Example 1.

Figures 3A and 3B show photographs demonstrating the cleaning effect of in-situ cleaning, as detailed in Example 1.

Figures 4A and 4B show the cleaning effect of in-situ cleaning as detailed in Example 5.

5A and 5B XeF lines were increased after an elapsed time period filament weight (FIG. 5A) and a _second flow chart filament current (Fig. 5B).

Figure 6 is a graph of filament weight change as a function of filament current for tungsten transport in a system with XeF ₂ flow.

Figure 7 is a graph showing changes in cathode bias power as a function of time and gas type.

Figure 8 is a graph showing the change in cathode W weight as a function of bias power.

Claims (8)

A method of controlling the state of an indirectly heated cathode source in an ion implantation system, the method comprising: a) determining a power consumption of the indirectly heated cathode source by measuring a cathode bias power for a predetermined time; Comparing the used power with the initial power for the predetermined time; and c) taking a corrective action (i) or (ii) in response to the comparison to control the state of the indirectly heated cathode, whereby (i) the predetermined time The indirectly heated cathode is etched when the used power is higher than the initial power; or (ii) the indirectly heated cathode is regenerated if the used power is lower than the initial power for the predetermined time. The method of claim 1, wherein the etching of (c)(i) comprises operating the indirectly heated cathode at a low to moderate temperature sufficient for etching. The method of claim 1, wherein the regrowth of (c)(ii) comprises flowing a fluorinated gas over the indirectly heated cathode under a plasma condition. The method of claim 3, wherein the fluorinated gas comprises one or more of the following: XeF ₂ , XeF ₄ , XeF ₆ , GeF ₄ , SiF ₄ , BF ₃ , AsF ₅ , AsF ₃ , PF ₅ , PF ₃ , F ₂ , TaF ₃ , TaF ₅ , WF ₆ , WF ₅ , WF ₄ , NF ₃ , IF ₅ , IF ₇ , KrF ₂ , SF ₆ , C ₂ F ₆ , CF ₄ , ClF ₃ , N ₂ F ₄ , N ₂ F ₂ , N ₃ F, NFH ₂ , NH ₂ F, BrF ₃ , C ₃ F ₈ , C ₄ F ₈ , C ₅ F ₈ , CHF ₃ , CH ₂ F ₂ , CH ₃ F, COF ₂ , HF C ₂ HF ₅ , C ₂ H ₂ F ₄ , C ₂ H ₃ F ₃ , C ₂ H ₄ F ₂ , C ₂ H ₅ F, C ₃ F ₆ and MoF ₆ . The method of claim 1, wherein the regrowth of (c)(ii) is sufficient to The indirectly heated cathode is operated under high temperature conditions of green metal deposition. The method of claim 4, wherein the fluorinated gas comprises one or more of XeF ₂ and N ₂ F ₄ . A method of operating an ion implantation system, the ion implantation system including a cathode in an arc chamber of an ion source, in order to maintain operational efficiency of the ion source, the method comprising the cathode under the following conditions The tungsten reagent is contacted, the conditions being selected from the group consisting of: (a) conditions for achieving deposition of tungsten on the cathode; and (b) conditions for effecting etching of the deposited material from the cathode, and according to a row The contacting is performed to maintain the cathode power by a predetermined limit including at least a predetermined resistance, and to control the temperature of the cathode and the temperature in the arc chamber wall to effectively deposit or etch material to the cathode. The predetermined resistance is maintained. A method of cleaning one or more components of an ion implantation system for at least partially removing deposits associated with ionization from the one or more components, the method comprising flowing a purge gas under the following conditions Through the system, the conditions are selected from the group consisting of: (a) achieving conditions under which the material is deposited on the cathode; and (b) achieving conditions for etching the deposited material from the cathode, wherein the cleaning gas comprises XeF ₂ and the purge gas flows through the system at sufficient time intervals to maintain leakage current when the operation of the system is below a predetermined limit.