Extension of Cathode and Repeller Lifetimes by Active Management of the Halogen Cycle

Abstract

A system and method for extending the life of the cathode and repeller in an IHC ion source is disclosed. The system monitors the health of the cathode by operating with a known set of parameters and measuring the bias power used to generate a desired extracted beam current or a desired current from an arc voltage power supply. Based on the measured bias power, the system can determine if the cathode is becoming too thin and can take corrective action. The corrective action can be to alert an operator, operate the IHC ion source with a predetermined set of parameters, or change the degree of dilution used in the IHC source. By taking these actions, the life of the cathode can be more than doubled.

Description

Technical Field

[0001] This application claims the benefit of priority to U.S. Patent Application No. 17 / 308,732, filed May 5, 2021, the disclosure of which is hereby incorporated by reference in its entirety.

[0002] The present disclosure relates to systems and methods for extending the life of cathodes and repellers within an ion source, and more particularly to actively managing a halogen cycle to extend the life of these components.

Background Art

[0003] Semiconductor devices are manufactured using multiple processors, some of which inject ions into a workpiece. One mechanism that can be used to create ions is an indirectly heated cathode (IHC) ion source. The IHC ion source includes a filament disposed behind the cathode. The cathode can be maintained at a higher positive voltage than the filament. When current is passed through the filament, the filament emits thermoelectrons, which are accelerated toward the more positively charged cathode. These thermoelectrons heat the cathode, causing the cathode to emit electrons into the chamber of the ion source. The cathode is disposed at one end of the chamber. The repeller is typically disposed at the end of the chamber opposite the cathode.

[0004] In certain embodiments, the ion source is configured to generate monovalent ions. In other embodiments, the ion source is configured to generate polyvalent ions such as P 2+ or P 3+ It has been found that the generation of polyvalent ions can contribute to cathode erosion and eventual puncturing. Specifically, charged ions accelerate towards the cathode and sputter the cathode. A similar phenomenon can occur with respect to the repeller. Thus, the life of the cathode and repeller can be a limiting factor in source life for configurations that generate polyvalent ions.

[0005] Therefore, it would be beneficial to have a system and method that can extend the life of the cathode. Further, it would be advantageous if this system and method could be immediately adopted for existing IHC ion sources without using any new or redesigned components. SUMMARY OF THE INVENTION

[0006] A system and method for extending the life of the cathode and repeller in an IHC ion source are disclosed. The system monitors the cathode's health by operating using a known set of parameters and measuring the bias power used to generate a desired extraction current or a desired current from an arc voltage power supply. Based on the measured bias power, the system can determine whether the cathode is too thin and take corrective action. This corrective action can be to alert the operator, operate the IHC ion source using a predetermined set of parameters, or change the degree of dilution used within the IHC source. By taking these actions, the life of the cathode can be increased by more than twofold.

[0007] According to one embodiment, an ion source is disclosed. The ion source includes a chamber having a plurality of walls, a cathode disposed at one end of the chamber, a gas inlet that enables introduction of one or more gases into the chamber, and a controller. The controller operates the ion source using a known recipe and adjusts a first parameter of the ion source to maintain a second parameter at a predetermined value. The value of the first parameter indicates the thickness of the cathode, and the controller initiates an action based on the thickness. In a particular embodiment, the second parameter includes the total extraction current from the chamber. In some embodiments, the ion source includes an arc voltage power supply for biasing the cathode with respect to the chamber, and the second parameter includes the current drawn from the arc voltage power supply. In a particular embodiment, the first parameter includes bias power. In some embodiments, the first parameter is selected from the group consisting of bias current, bias voltage, bias impedance, filament power, filament current, filament voltage, and filament resistance. In a particular embodiment, the action includes an alarm to the operator. In some embodiments, the action includes operating the ion source with a particular recipe. In some embodiments, when it is determined that the thickness of the cathode is less than a predetermined thickness, the particular recipe includes a low arc voltage recipe. In a particular embodiment, the low arc voltage recipe is operated without dilution. In some embodiments, when it is determined that the thickness of the cathode is greater than a predetermined thickness, the particular recipe includes a high arc voltage recipe. In a particular embodiment, the action includes adjusting the flow rate of a dilution gas into the chamber. In some embodiments, when it is determined that the thickness of the cathode is less than a predetermined thickness, the flow rate of the dilution gas is decreased. In some embodiments, when it is determined that the thickness of the cathode is greater than a predetermined thickness, the flow rate of the dilution gas is increased.

[0008] According to another embodiment, a method for monitoring and extending the life of a cathode within an Indirect Heating Cathode (IHC) ion source is disclosed. The method includes operating the IHC ion source using a known recipe and monitoring a first parameter used to maintain a second parameter at a predetermined value, where the value of the first parameter indicates the thickness of the cathode, monitoring, comparing the first parameter with a predetermined upper limit value and a predetermined lower limit value, and taking an action based on the comparison. In a particular embodiment, the second parameter includes the total extraction current from the IHC ion source. In some embodiments, the IHC ion source includes an arc voltage power supply for biasing the cathode with respect to the chamber of the IHC ion source, and the second parameter includes the current drawn from the arc voltage power supply. In a particular embodiment, the first parameter includes bias power. In some embodiments, the first parameter is selected from the group consisting of bias current, bias voltage, bias impedance, filament power, filament current, filament voltage, and filament resistance. In a particular embodiment, the action includes alerting an operator. In some embodiments, the action includes operating the ion source with a particular recipe. In some embodiments, the particular recipe includes a low arc pressure recipe when it is determined that the thickness of the cathode is less than a predetermined thickness. In a particular embodiment, the low arc voltage recipe is operated without dilution. In some embodiments, the particular recipe includes a high arc voltage recipe when it is determined that the thickness of the cathode is greater than a predetermined thickness. In a particular embodiment, the action includes adjusting the flow rate of a dilution gas into the chamber. In some embodiments, the flow rate of the dilution gas is decreased when it is determined that the thickness of the cathode is less than a predetermined thickness. In some embodiments, the flow rate of the dilution gas is increased when it is determined that the thickness of the cathode is greater than a predetermined thickness.

[0009] To better understand the present disclosure, reference is made to the accompanying drawings, in which like elements are referred to by like reference numerals.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0011] Figure 1 shows an IHC ion source 10 that solves these problems. The IHC ion source 10 includes a chamber 100 having two opposite ends and walls 101 connecting these ends. These walls 101 include side walls, an extraction plate 103, and a bottom wall opposite the extraction plate 103. The extraction plate 103 includes an extraction aperture 140 through which ions are extracted. The walls 101 of the chamber 100 may be made of a conductive material and can be in electrical communication with each other. A cathode 110 is disposed within the chamber 100 at a first end 104 of the chamber 100. A filament 160 is disposed behind the cathode 110. The filament 160 is in electrical communication with a filament power supply 165. The filament power supply 165 is configured to pass a current through the filament 160, and thus the filament 160 emits thermoelectrons. A cathode bias power supply 115 applies a negative bias to the filament 160 with respect to the cathode 110, so that these thermoelectrons are accelerated from the filament 160 toward the cathode 110 and heat the cathode 110 when the thermoelectrons collide with the back of the cathode 110. The cathode bias power supply 115 can bias the filament 160 such that the filament has a voltage that is negative with respect to the voltage of the cathode 110, for example, between 200V and 1500V. The cathode 110 then emits thermoelectrons from the front of the cathode into the chamber 100.

[0012] Accordingly, the filament power supply 165 supplies a current to the filament 160. The cathode bias power supply 115 biases the filament 160 such that the filament is more negative than the cathode 110, so that electrons are attracted from the filament 160 toward the cathode 110. The cathode 110 communicates with an arc voltage power supply 111. The arc voltage power supply 111 supplies a voltage to the cathode with respect to the chamber 100. This arc voltage accelerates the thermoelectrons emitted into the arc chamber at the cathode to ionize the neutral gas. The current drawn by this arc voltage power supply 111 is a measurement of the amount of current driven through the plasma. In certain embodiments, the wall 101 provides a ground reference to other power supplies.

[0013] In this embodiment, the repeller 120 is disposed within the chamber 100 at the second end 105 of the chamber 100 on the side opposite to the cathode 110. The repeller 120 can communicate electrically with a repeller power supply 123. As its name indicates, the repeller 120 functions to repel the electrons emitted from the cathode 110 and return them towards the center of the chamber 100. For example, in certain embodiments, the repeller 120 can be biased at a negative voltage with respect to the chamber 100 to repel electrons. For example, in certain embodiments, the repeller 120 can be biased at 0 to -150 V with respect to the chamber 100. In certain embodiments, the repeller 120 can be floated with respect to the chamber 100. In other words, when floated, the repeller 120 is not electrically connected to the repeller power supply 123 or the chamber 100. In this embodiment, the voltage of the repeller 120 tends to drift to a voltage close to the voltage of the cathode 110. Alternatively, the repeller 120 may be electrically connected to the wall 101.

[0014] In certain embodiments, a magnetic field 190 is generated within the chamber 100. This magnetic field is for restricting the electrons along one direction. The magnetic field 190 typically runs from the first end 104 to the second end 105 parallel to the wall 101. For example, the electrons can be confined within a cylinder parallel to the direction from the cathode 110 to the repeller 120 (i.e., the y direction). Thus, the electrons do not receive an electromagnetic force to move in the y direction. However, the movement of the electrons in other directions can receive an electromagnetic force.

[0015] One or more gas containers 108 can communicate with the chamber 100 via the gas inlet 106. Each gas container 108 can include a mass flow controller (MFC) to regulate the gas flow from each gas container.

[0016] An extraction power supply 170 can be used to bias the IHC ion source 10 relative to the rest of the components within the beamline. For example, the platen 260 (see FIG. 2) can be at a first voltage such as ground, but a positive voltage is applied to the IHC ion source 10 so that the IHC ion source 10 is biased more positively than the platen 260. Thus, the voltage supplied by the extraction power supply 170 is referred to as the extraction voltage and determines the energy of the ions extracted from the IHC ion source 10. Further, the current supplied by the extraction power supply 170 is a measure of the total extraction beam current.

[0017] In certain embodiments, there is a feedback loop between the cathode bias power supply 115 and the extraction power supply 170. Specifically, it may be desirable to maintain the extracted beam current at a constant value. Thus, the current supplied by the extraction power supply 170 may be monitored and the output of the cathode bias power supply 115 may be adjusted to maintain a constant extraction current. This feedback loop may be implemented by the controller 180 or in some other way.

[0018] The controller 180 can communicate with one or more of the power supplies so that the voltage or current supplied by these power supplies can be monitored and / or corrected. Further, the controller 180 can communicate with the MFC of each gas container 108 to adjust the flow of each gas into the chamber 100. The controller 180 can include a processing device such as a microcontroller, a personal computer, a dedicated controller, or another suitable processing device. The controller 180 can also include a non-transitory storage element such as a semiconductor memory, a magnetic memory, or another suitable memory. This non-transitory storage element can include instructions and other data that enable the controller 180 to perform the functions described herein. For example, the controller 180 can communicate with the cathode bias power supply 115 to enable the IHC ion source 10 to vary the voltage applied to the filament 160 as a cathode. The controller 180 can also communicate with the repeller power supply 123 to bias the repeller. Further, the controller 180 may be able to monitor the voltage, current, and / or power supplied by the cathode bias power supply 115.

[0019] FIG. 2 shows an ion implantation system using the IHC ion source 10 of FIG. 1. One or more electrodes 200 are disposed outside and in the vicinity of the extraction aperture of the IHC ion source 10.

[0020] Downstream of the electrode 200, a mass analyzer 210 is positioned. The mass analyzer 210 uses a magnetic field to guide the path of the extracted ions 1. The magnetic field acts on the flight path of the ions according to the mass and charge of the ions. A mass resolving device 220 having a resolving aperture 221 is disposed at the output of the mass analyzer 210, i.e., at the distal end. By appropriately selecting the magnetic field, only the ions 1 having the selected mass and charge are directed through the resolving aperture 221. Other ions collide with the mass resolving device 220 or the walls of the mass analyzer 210 and do not proceed further within the system.

[0021] The collimator 230 can be disposed downstream of the mass analyzer 220. The collimator 230 receives the ions 1 that have passed through the resolving aperture 221 and creates a ribbon ion beam formed of a plurality of parallel or substantially parallel beamlets. The output of the mass spectrometer 210, i.e., the distal end, and the input of the collimator 230, i.e., the proximal end, are separated by a fixed distance. The mass analyzer 220 is disposed in the space between these two components.

[0022] Downstream of the collimator 230, an acceleration / deceleration stage 240 can be located. The acceleration / deceleration stage 240 may be referred to as an energy purity module. The energy purity module is a beamline lens component configured to independently control the deflection, deceleration, and focusing of the ion beam. For example, the energy purity module can be a vertical electrostatic energy filter (VEEF) or an electrostatic filter (EF). Downstream of the acceleration / deceleration stage 240, a platen 260 is located. The workpiece is disposed on the platen 260 during processing.

[0023] A certain set of operating parameters, also called a recipe, can be utilized to generate ions of a desired charge. For example, a recipe including a lower arc voltage can create a first distribution of charged ions that results in a low cathode erosion rate and, in some cases, even cathode growth. In one embodiment, the arc voltage is 80 V or less in such a recipe. This may be referred to as a low arc voltage recipe. A recipe including a higher arc voltage can be used to create a second distribution of charged ions that causes a high cathode erosion rate. For example, in one embodiment, the arc voltage can be greater than 80 V. This may be referred to as a high arc voltage recipe. In a particular embodiment, one difference between the first distribution and the second distribution can be the percentage of multiply charged ions.

[0024] Thus, in certain embodiments, a high arc voltage recipe can be defined as a recipe that utilizes an arc voltage that exceeds a predetermined threshold, while a low arc voltage recipe utilizes an arc voltage that is below this predetermined threshold. In certain embodiments, this predetermined voltage can be 80V, although the specific threshold can depend on the type of species and type of recipe being executed on the IHC ion source 10.

[0025] Some high arc voltage recipes can be those used to create polyvalent ions and utilize halogen-based gases. For example, PF3 can be used to implant phosphorus. NF3 can be used to implant nitrogen. BF3 can be used to implant boron. Aluminum can be implanted by using elemental aluminum and NF3. Gallium can be implanted by using elemental gallium and NF3. Antimony can be implanted using SbF5. Of course, other species can be implanted using halogen-based gases.

[0026] These high arc voltage recipes can also tend to sputter material from the cathode 110, causing the cathode 110 to become thinner over time. This is due to ions colliding with the cathode 110 and sputtering the cathode, and the higher the energy of the ions, which is determined by the arc voltage and charge state, the greater the sputtering rate. If left unexamined, this can ultimately cause cathode punch-through, where holes are created that completely penetrate the cathode 110. When this occurs, the cathode 110 is replaced, so the IHC ion source 10 cannot be operated for a period of time. In certain embodiments, this can occur after operating for less than 100 hours with a recipe that generates polyvalent ions.

[0027] Furthermore, low arc voltage recipes that can be used primarily to create monovalent ions, particularly recipes that include halogens, tend to remove tungsten from the walls of the IHC ion source 10 and deposit this tungsten onto the cathode 110 and the repeller 120. For example, ionized fluorine can react with the walls of the ion source to form tungsten hexafluoride, which is then deposited onto the cathode 110. To mitigate this, these recipes are often operated using dilution, for example by introducing hydrogen into the chamber 100. Hydrogen reacts with some of the ionized fluorine to reduce the interaction between the fluorine ions and the tungsten walls.

[0028] In other words, if halogen-based high arc voltage recipes are used continuously, the cathode 110 will erode and eventually cease to function due to punch-through. Conversely, if halogen-based low arc voltage recipes are used continuously without dilution, the cathode 110 will thicken as additional tungsten is deposited onto the cathode. At some point, the thickness of the cathode 110 will become too thick to be adequately regulated by the cathode bias power supply 115.

[0029] It has been found that as the cathode 110 becomes thinner, the amount of bias power required to achieve the desired extraction beam current decreases. Bias power is defined as the voltage supplied by the cathode bias power supply 115 multiplied by the current supplied by the cathode bias power supply 115. Conversely, as the cathode 110 becomes thicker, the amount of bias power required to achieve the desired extraction beam current increases. An example of this is shown in FIG. 3. The extraction current is kept constant during this time. It should be noted that during the first period 300, which is 67% of the operating time, the ion source was operated with a high arc voltage recipe. This high arc voltage halogen-based recipe removes material from the cathode 110. Note that the bias power decreases as the cathode becomes thinner during this period. During the second period 310, which is only 42% of the operating time, the ion source was operating with a high arc voltage recipe, and the remaining operating time was with a low arc voltage recipe. Note that the bias power increases during this period. This is due to the halogen cycle from the low arc voltage recipe, in which tungsten from the walls is removed by halogens in the plasma and redeposited on the cathode 110 and the repeller 120, thickening those components.

[0030] Therefore, one way to determine the integrity of the cathode 110 can be by monitoring the bias power, as shown in FIG. 4.

[0031] In this embodiment, as shown in box 400, a known recipe is used within the IHC ion source 10. This known recipe may be a commonly used recipe or a recipe used during idle time. This recipe may be a halogen-based recipe or a halogen-free recipe. This known recipe may also be called a cathode integrity recipe. The recipe can include the species to be used, the flow rate of the species, the desired extraction voltage, the desired arc voltage, and other parameters.

[0032] Next, as shown in box 410, the controller 180 monitors the total extraction beam current, for example using the extraction power supply 170. As shown in box 420, the controller 180 varies the bias power by modifying the output from the cathode bias power supply 115 so that the total extraction current maintains a predetermined value. Next, as shown in box 430, the controller 180 records the bias power used to generate a predetermined extraction current. Alternatively, the total arc or plasma current in the source can be used as feedback of the bias current by an arc voltage power supply, i.e., a power supply that biases the cathode with respect to the chamber ground. This is shown in FIG. 5.

[0033] Next, as shown in box 440, the controller 180 compares this bias power with a predetermined upper threshold and a predetermined lower threshold. These upper and lower thresholds can be determined empirically or calculated using another technique. For example, the lower threshold can be established by determining the bias power at which punch-through occurs and adding a safety margin to this value. The upper threshold can be established by determining the bias power at which it is no longer possible to adjust the extraction current and subtracting a safety margin from that value. These upper and lower thresholds can be a function of the cathode integrity recipe.

[0034] Based on the result of this comparison, the controller 180 can initiate an action, as shown in box 450. Specifically, an action can be initiated if the bias power is near or below the lower threshold, or near or above the upper threshold. Alternatively, if the bias power is between the two thresholds, no action need be taken, as shown in box 460. The sequence shown in FIG. 4 can be repeated at regular time intervals, for example every 8 hours, or at a specific recipe transition. In this way, the integrity of the cathode 110 can be monitored over time. The ideal frequency of this monitoring is a function of the recipe mix utilized within the ion source.

[0035] Accordingly, the present disclosure presents a system and method for monitoring the state of cathode 110 by tracking bias power while delivering a predetermined extraction beam current using a known recipe. While the above disclosure describes the use of bias power to monitor cathode health, other parameters may be used. For example, parameters such as bias voltage, bias current, bias impedance defined as bias voltage divided by bias current, filament power, filament current, filament voltage, or filament resistance may be used to track cathode health.

[0036] A second method of determining the health of cathode 110 may be by monitoring bias power while maintaining a constant current drawn from arc voltage power supply 111, as shown in FIG. 5. In this embodiment, instead of attempting to maintain a constant extraction beam current, the current from arc voltage power supply 111 is maintained at a constant value.

[0037] Accordingly, this sequence is very similar to the sequence shown in FIG. 4. However, instead of monitoring the extraction beam current, controller 180 monitors the total current drawn by arc voltage power supply 111, as shown in box 470. The remainder of the sequence is as described above.

[0038] Accordingly, in both embodiments, the controller adjusts a first parameter to maintain a second parameter at a predetermined value, and the value of the first parameter indicates the thickness of the cathode. FIGS. 4 and 5 show the first parameter as bias power, but the first parameter is not limited to this parameter. For example, as described above, the first parameter may be bias current, bias voltage, bias impedance, filament power, filament current, filament voltage, or filament resistance. The second parameter may be the total extraction current or the current drawn from the arc voltage power supply.

[0039] This technique for monitoring the integrity of the cathode 110 can be used in a plurality of ways.

[0040] In one embodiment, the action starting at box 450 can be an alert to the operator, informing the operator that the cathode 110 is nearly failed and that a corrective action should be taken. For example, when the bias power is near the lower threshold, the corrective action may be to inform the operator and operate the ion source using a low arc voltage recipe. Conversely, when the bias power is near the upper threshold, the corrective action may be to operate using a high arc voltage recipe. Executing this corrective action over a period of time, for example, over 1 hour, 1 to 6 hours, etc., can serve to improve the integrity either by adding material to the cathode 110 or removing material from the cathode 110 to return the bias power to the acceptable range. This approach maximizes the flexibility of the operator's decision on when to perform the corrective action.

[0041] In another embodiment, the action starting at box 450 can be to enable the controller 180 to automatically perform a predetermined corrective action. For example, when the monitored bias power approaches the lower threshold, the controller 180 can start a low arc voltage recipe to regenerate the cathode 110. To achieve the fastest growth, this halogen-based low arc voltage recipe can be operated without dilution to maximize the halogen growth of the cathode 110. Conversely, when the monitored bias power approaches the upper threshold, the controller 180 can start a high arc voltage recipe to thin the cathode 110. This corrective action may be started immediately, or the controller 180 can give the operator the option to schedule the corrective action at a convenient time.

[0042] In the third embodiment, the action starting at box 450 can be the active regulation of the halogen cycle by the controller 180. As described above, dilution is often used to shorten the halogen cycle so that less material is removed from the walls and not deposited on the cathode 110. In some embodiments, the diluent gas may be hydrogen or a gas such as PH3 or NH3 containing hydrogen. In certain embodiments, hydrogen is added at a first flow rate, which may be, for example, approximately 0.5 sccm, although other flow rates are possible. The introduction of hydrogen serves to shorten the halogen cycle for a halogen-based low arc voltage recipe. Thus, in one embodiment, the controller 180 can monitor the thickness of the cathode 110, as described, for example, in FIGS. 4 or 5. The controller 180 then actively adjusts the flow rate of the diluent gas in response. For example, when the cathode 110 approaches or reaches the lower limit of the cathode (with respect to thickness or bias power), the controller 180 can choose to decrease or disable the flow rate of the diluent gas for the halogen-based low arc voltage recipe. This action tends to grow material on the cathode 110. Conversely, when the cathode approaches or reaches the upper limit of the cathode (with respect to thickness or bias power), the controller 180 can choose to increase the flow rate of the diluent gas to further slow down the halogen cycle and thus prevent the bias power from continuing to increase. In certain embodiments, the flow rate of the diluent gas is varied as a function of the thickness of the cathode so that the cathode does not reach the upper or lower threshold. The flow rate of the diluent gas can be modified by the controller 180 by providing a control signal from the controller 180 to the MFC associated with the diluent gas.

[0043] The present system and method have many advantages. Currently, when the IHC ion source is operated for a long period of time with a high arc voltage recipe, the thickness of the cathode decreases. If not inspected, the cathode will cease to function and a repair procedure will be required. By monitoring the health of the cathode, preventive measures can be taken to extend the life of the cathode. Advantageously, the system and method described herein do not require any modification to the hardware configuration. Rather, the enhancements can be fully implemented in software, making it possible to retrofit this system and method onto an existing system. By monitoring the health of the cathode and adjusting the recipe used for the ion source, the life of the cathode can be made more than twice as long.

[0044] The present disclosure should not be limited in scope by the specific embodiments described herein. Indeed, various other embodiments and modifications of the present disclosure will be apparent to those skilled in the art in addition to those described herein from the foregoing description and the accompanying drawings. Accordingly, such other embodiments and modifications are intended to be within the scope of the present disclosure. Further, although the present disclosure has been described herein in the context of particular embodiments in a particular environment for a particular purpose, those skilled in the art will recognize that the utility of the present disclosure is not limited to those embodiments, and that the present disclosure can be beneficially implemented in any number of environments for any number of purposes. Accordingly, the claims set forth below should be construed in view of the full scope and spirit of the present disclosure as described herein.

Claims

1. An ion source comprising: a chamber having a plurality of walls; a cathode disposed at one end of the chamber; a gas inlet enabling introduction of one or more gases into the chamber; a controller wherein the controller operates the ion source using a known recipe and adjusts a first parameter of the ion source to maintain a second parameter including the total extraction current from the chamber at a predetermined value, the value of the first parameter indicating the thickness of the cathode, and the controller initiates an action based on the thickness. An ion source.

2. An ion source comprising: a chamber having a plurality of walls; a cathode disposed at one end of the chamber; a gas inlet enabling introduction of one or more gases into the chamber; an arc voltage power supply for biasing the cathode with respect to the chamber; a controller wherein the controller operates the ion source using a known recipe and adjusts a first parameter of the ion source to maintain a second parameter including the current drawn from the arc voltage power supply at a predetermined value, the value of the first parameter indicating the thickness of the cathode, and the controller initiates an action based on the thickness. An ion source.

3. An ion source comprising: a chamber having a plurality of walls; a cathode disposed at one end of the chamber; a gas inlet enabling introduction of one or more gases into the chamber; a controller wherein the controller operates the ion source using a known recipe and adjusts a first parameter including the bias power of the ion source to maintain a second parameter at a predetermined value, the value of the first parameter indicating the thickness of the cathode, and the controller initiates an action based on the thickness. An ion source.

4. An ion source comprising: a chamber having a plurality of walls; a cathode disposed at one end of the chamber; a gas inlet enabling introduction of one or more gases into the chamber; a controller wherein the controller operates the ion source using a known recipe and adjusts a first parameter of the ion source to maintain a second parameter including the total extraction current from the chamber at a predetermined value, the value of the first parameter indicating the thickness of the cathode, and the controller initiates an action based on the thickness. An ion source. The controller operates the ion source using a known recipe and adjusts a first parameter selected from the group consisting of the bias current, bias voltage, bias impedance, filament power, filament current, filament voltage, and filament resistance of the ion source so as to maintain a second parameter at a predetermined value, the value of the first parameter indicating the thickness of the cathode, An ion source, wherein the controller initiates an action based on the thickness. **Claim 5** An ion source comprising: A chamber having a plurality of walls; A cathode disposed at one end of the chamber; A gas inlet enabling introduction of one or more gases into the chamber; And a controller wherein the controller operates the ion source using a known recipe and adjusts a first parameter of the ion source so as to maintain a second parameter at a predetermined value, the value of the first parameter indicating the thickness of the cathode, the controller initiates an action including operating the ion source with a specific recipe based on the thickness, when it is determined that the thickness of the cathode is less than a predetermined thickness, the specific recipe includes a low arc voltage recipe. An ion source. **Claim 6** An ion source comprising: A chamber having a plurality of walls; A cathode disposed at one end of the chamber; A gas inlet enabling introduction of one or more gases into the chamber; And a controller wherein the controller operates the ion source using a known recipe and adjusts a first parameter of the ion source so as to maintain a second parameter at a predetermined value, the value of the first parameter indicating the thickness of the cathode, the controller initiates an action including operating the ion source with a specific recipe based on the thickness, when it is determined that the thickness of the cathode is greater than a predetermined thickness, the specific recipe includes a high arc voltage recipe. An ion source. **Claim 7** The ion source according to any one of claims 3 to 6, wherein the second parameter includes the total extraction current from the chamber. **Claim 8** The ion source according to any one of claims 3 to 6, further comprising an arc voltage power supply for applying a bias to the cathode with respect to the chamber, wherein the second parameter includes the current drawn from the arc voltage power supply. **Claim 9** The ion source according to any one of claims 1 to 2 or 5 to 6, wherein the first parameter includes bias power.

10. The ion source according to any one of claims 1 to 2 or 5 to 6, wherein the first parameter is selected from the group consisting of bias current, bias voltage, bias impedance, filament power, filament current, filament voltage, and filament resistance.

11. The ion source according to any one of claims 1 to 4, wherein the action includes an alarm to an operator.

12. The ion source according to any one of claims 1 to 4, wherein the action includes operating the ion source with a specific recipe.

13. The ion source according to claim 12, wherein when it is determined that the thickness of the cathode is less than a predetermined thickness, the specific recipe includes a low arc voltage recipe.

14. The ion source according to claim 12, wherein when it is determined that the thickness of the cathode is greater than a predetermined thickness, the specific recipe includes a high arc voltage recipe.

15. The ion source according to any one of claims 1 to 4, wherein the action includes adjusting the flow rate of a dilution gas into the chamber.

16. The ion source according to claim 15, wherein when it is determined that the thickness of the cathode is less than a predetermined thickness, the flow rate of the dilution gas is decreased.

17. The ion source according to claim 15, wherein when it is determined that the thickness of the cathode is greater than a predetermined thickness, the flow rate of the dilution gas is increased.

18. A method for monitoring and extending the life of a cathode in an indirectly heated cathode (IHC) ion source, comprising: operating the IHC ion source using a known recipe; monitoring a first parameter used to maintain a second parameter, including the total extraction current from the chamber of the IHC ion source, at a predetermined value, wherein the value of the first parameter indicates the thickness of the cathode; comparing the first parameter with a predetermined upper limit value and a predetermined lower limit value; performing an action based on the comparison; and including a method.

19. A method for monitoring and extending the life of a cathode in an indirectly heated cathode (IHC) ion source, comprising: Operating the IHC ion source comprising an arc voltage power supply for applying a bias to the cathode with respect to the chamber of the IHC ion source using a known recipe; Monitoring a first parameter used to maintain a second parameter including a current drawn from the arc voltage power supply at a predetermined value, the first parameter being a parameter whose value indicates the thickness of the cathode; Comparing the first parameter with a predetermined upper limit value and a predetermined lower limit value; Taking an action based on the comparison; A method comprising: **Claim 20** A method for monitoring and extending the life of a cathode in an indirectly heated cathode (IHC) ion source, comprising: Operating the IHC ion source using a known recipe; Monitoring a first parameter including bias power used to maintain a second parameter at a predetermined value, the first parameter being a parameter whose value indicates the thickness of the cathode; Comparing the first parameter with a predetermined upper limit value and a predetermined lower limit value; Taking an action based on the comparison; A method comprising: **Claim 21** A method for monitoring and extending the life of a cathode in an indirectly heated cathode (IHC) ion source, comprising: Operating the IHC ion source using a known recipe; Monitoring a first parameter selected from the group consisting of bias current, bias voltage, bias impedance, filament power, filament current, filament voltage, and filament resistance used to maintain a second parameter at a predetermined value, the first parameter being a parameter whose value indicates the thickness of the cathode; Comparing the first parameter with a predetermined upper limit value and a predetermined lower limit value; Taking an action based on the comparison; A method comprising: **Claim 22** A method for monitoring and extending the life of a cathode in an indirectly heated cathode (IHC) ion source, comprising: Operating the IHC ion source using a known recipe; Monitoring a first parameter used to maintain a second parameter at a predetermined value, the first parameter being a parameter whose value indicates the thickness of the cathode; Comparing the first parameter with a predetermined upper limit value and a predetermined lower limit value; Performing an action based on the comparison, wherein the action includes operating the IHC ion source according to a specific recipe, and when it is determined that the thickness of the cathode is less than a predetermined thickness, the specific recipe includes a low arc pressure recipe, and performing the action Including, method.

23. A method for monitoring and extending the life of a cathode in an indirectly heated cathode (IHC) ion source, comprising: Operating the IHC ion source using a known recipe; Monitoring a first parameter used to maintain a second parameter at a predetermined value, wherein the value of the first parameter indicates the thickness of the cathode, and monitoring the first parameter; Comparing the first parameter with a predetermined upper limit value and a predetermined lower limit value; Performing an action based on the comparison, wherein the action includes operating the IHC ion source according to a specific recipe, and when it is determined that the thickness of the cathode is greater than a predetermined thickness, the specific recipe includes a high arc voltage recipe, and performing the action Including, method.

24. The method according to any one of claims 20 to 23, wherein the second parameter includes the total extraction current from the chamber of the IHC ion source.

25. The method according to any one of claims 20 to 23, wherein the IHC ion source is provided with an arc voltage power supply for applying a bias to the cathode with respect to the chamber of the IHC ion source, and the second parameter includes the current drawn from the arc voltage power supply.

26. The method according to any one of claims 18 to 19 or 22 to 23, wherein the first parameter includes bias power.

27. The method according to any one of claims 18 to 21, wherein the action includes issuing an alarm to an operator.

28. The method according to any one of claims 18 to 21, wherein the action includes operating the IHC ion source according to a specific recipe, and when it is determined that the thickness of the cathode is less than a predetermined thickness, the specific recipe includes a low arc pressure recipe.

29. The method according to any one of claims 18 to 21, wherein the action includes operating the IHC ion source according to a specific recipe, and when it is determined that the thickness of the cathode is greater than a predetermined thickness, the specific recipe includes a high arc voltage recipe.

30. The method according to any one of claims 18 to 21, wherein the action includes adjusting the flow rate of a dilution gas into the chamber of the IHC ion source.

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