Abstract:
An ion implantation system, having a temperature controlled ion source chamber is disclosed. The temperature of the ion source chamber is regulated by disposing a heat sink in proximity to the ion source chamber. A gas fillable chamber is disposed between and in physical communication with both the ion source chamber and the heat sink. By controlling the amount of gas, i.e. the gas pressure, within the gas fillable chamber, the coefficient of heat transfer can be manipulated. This allows the temperature of the ion source chamber to be controlled through the application or removal of gas from the gas fillable chamber. This independent temperature control decouples the power used to heat the ion generator from the ion species that are ultimately generated.

Description:
[0001]    Embodiments of the present disclosure relate to a method and apparatus for controlling the temperature of an ion source chamber in an ion implantation system. 
       BACKGROUND 
       [0002]    Ion implantation is a process by which dopants or impurities are introduced into a substrate via bombardment. In semiconductor manufacturing, the dopants are introduced to alter electrical, optical, or mechanical properties. For example, dopants may be introduced into an intrinsic semiconductor substrate to alter the type and level of conductivity of the substrate. In manufacturing an integrated circuit (IC), a precise doping profile is often important for proper IC performance. To achieve a desired doping profile, one or more dopants may be implanted in the form of ions in various doses and various energy levels. 
         [0003]    Referring to  FIG. 1 , there is shown a conventional ion implantation system  100 . As illustrated in the figure, the ion implantation system  100  may comprise an ion source and a complex series of beam-line components through which an ion beam  10  passes. The ion source may comprise an ion source chamber  102  where desired ions are generated. The ion source may also comprise a power source  101  and an extraction electrode  104  disposed near the ion source chamber  102 . As illustrated in the figure, the extraction electrodes  104  may include a suppression electrode  104   a  and a ground electrode  104   b.  Each of the ion source chamber  102 , the suppression electrode  104   a,  and the ground electrode  104   b  may include an aperture: the ion source chamber  102  may include an extraction aperture (not shown), the suppression electrode may include a suppression electrode aperture (not shown), and a ground electrode may include a ground electrode aperture (not shown). The apertures may be in communication with one another so as to allow the ions generated in the ion source chamber  102  may pass through, toward the beam-line components. 
         [0004]    The beam-line components, meanwhile, may include, for example, a mass analyzer  106 , a first acceleration or deceleration (A1 or D1) stage  108 , a collimator  110 , and a second acceleration or deceleration (A2 or D2) stage  112 . Much like a series of optical lenses that manipulate a light beam, the beam-line components can filter, focus, and manipulate ions or ion beam  10  having desired species, shape, energy, and other qualities. The ion beam  10  that passes through the beam-line components may be directed toward a substrate  114  that is mounted on a platen  116  or clamp. The substrate  114  may be moved in one or more dimensions (e.g., translate, rotate, and tilt) by an apparatus, sometimes referred to as a “roplat.” It should be appreciated by those skilled in the art that the entire path traversed by the ion beam  10  is typically evacuated during ion implantation. 
         [0005]    The ion source included in the ion implanter system  10  may be an indirectly heated cathode (IHC) source. In an IHC system, a cathode and a repeller electrode (or anti-cathode) may be positioned in the opposite sides of the ion source chamber  102 . A filament may be positioned outside the ion source chamber  102  and in close proximity to the cathode in order to heat the cathode. 
         [0006]    The ion source is required to generate a stable, well-defined ion beam  10  for a variety of different ion species and extraction voltages. In some embodiments, the temperature of the ion source, and particularly, the temperature of the ion source chamber  102 , is important in determining the types of ions that are created and extracted. For example, when boron trifluorine (BF 3 ) is used as a source or feed gas, it may become various ions, such as BF 2   + , BF + , or B. It is the temperature within the ion source chamber  102  that is one of the factors in determining which of these ions is created. Larger molecular ions, such as BF 2   +  are more likely created at lower temperatures, while atomic ions, like B +  are more likely created at higher temperatures. Typically, the temperature of the ion source chamber  102  is either not regulated, or is controlled by varying or regulating the amount of energy or power that is passed through the filament and used to heat the cathode. 
         [0007]    Higher levels of power may result in mono-atomic ions. Lower levels of power may result in larger or molecular ions. However, lower levels of energy also tend to decrease the amount of ions that are generated, thereby lowering the available beam current. For this reason, implants that require larger or molecular ions may take more time to process than those with smaller or atomic ions. In other words, power, which is responsible for determining beam current, can also be used to determine the ion species that are to be created. 
         [0008]    It would therefore be desirable to operate the ion source chamber such that the ion beam current and the ion species that are generated could be independently controlled. It would also be beneficial if larger or molecular ions could be generated at higher powers and thus with greater ion beam currents. 
       SUMMARY 
       [0009]    An ion implantation system, having a temperature controlled ion source chamber is disclosed. The temperature of the ion source chamber is regulated by disposing a heat sink in proximity to the ion source chamber. A gas fillable chamber is disposed between and in physical communication with both the ion source chamber and the heat sink. By controlling the amount of gas, i.e. the gas pressure, within the gas fillable chamber, the coefficient of heat transfer can be manipulated. This allows the temperature of the ion source chamber to be controlled through the application or removal of gas from the gas fillable chamber. This independent temperature control decouples the power used to heat the ion generator from the ion species that are ultimately generated. 
         [0010]    According to one embodiment, a method of producing an ion beam having a desired beam current and a desired ion composition is disclosed. The method comprises introducing a feed gas to an ion source chamber; applying power to an ion generator disposed in the ion source chamber to create a plasma having the desired beam current; and independently controlling a temperature of the ion source chamber by transferring a variable amount of heat away from the ion source chamber to create the ion beam of the desired ion composition. 
         [0011]    According to a second embodiment, an ion source is disclosed, comprising an ion generator disposed within an ion source chamber for the generation of ions; a temperature regulator in thermal communication with the ion source chamber to regulate a temperature of the ion source chamber by transferring a variable amount of heat away from the ion source chamber; and a controller in communication with the temperature regulator and the ion source chamber, so as to control power applied to the ion generator in the ion source chamber and the temperature of the ion source chamber, based on a desired ion beam current and ion beam composition. 
         [0012]    According to a third embodiment, an ion source is disclosed, comprising an ion generator disposed in an ion source chamber for the generation of ions; a heat sink; a gas fillable chamber, disposed between and in thermal communication with the ion source chamber and the heat sink; a gas source in communication with the gas fillable chamber; and a vacuum pump in communication with the gas fillable chamber, wherein the gas source and the vacuum pump regulate a pressure of gas contained within the gas fillable chamber. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0013]    For a better understanding of the present disclosure, reference is made to the accompanying drawings, which are incorporated herein by reference and in which: 
           [0014]      FIG. 1  is an ion implantation system in accordance with the prior art; 
           [0015]      FIG. 2  shows an ion source according to a first embodiment; 
           [0016]      FIG. 3  shows an ion source according to a second embodiment; 
           [0017]      FIG. 4  shows a graph showing the heat transfer coefficient of helium in a 1 mm gap as a function of pressure in that gap; 
           [0018]      FIG. 5  shows a graph representing the distribution of power when the gas fillable chamber is filled to a first pressure; 
           [0019]      FIG. 6  shows a graph representing the distribution of power when the gas fillable chamber is filled to a second pressure; and 
           [0020]      FIG. 7  shows an ion source according to a third embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]      FIG. 2  shows a representative ion source that may be used in accordance with one embodiment. In this system, there is an ion source  200 , which is in communication with a feed gas source  205 . Feed gas is supplied to the ion source  200  from a feed gas source  205 . The feed gas may be any suitable gas. For example, in some embodiments, a boron-containing gas, such as BF 3  or diborane, may be used. In other embodiments, a phosphorus containing gas, such as PH 3 , may be used. 
         [0022]    In one embodiment, the ion source  200  may include an ion generator housed within an ion source chamber  210 . This ion generator may be an indirectly heated cathode (IHC)  211  and a filament  212 . Other devices may also be used to create the desired ions, including an RF antenna. This ion source  200  may be contained within a larger housing (not shown). As the ion source  200  is typically biased at a substantial voltage, it may be necessary to electrically isolate the ion source  200  from the housing. This may be achieved through the use of source bushings. 
         [0023]    Also contained within the ion source  200  may be a heat sink  220 . This heat sink  220  may be a thermal conductive material, such as aluminum, copper or any other suitable material. This heat sink may be at the same bias voltage as the ion source chamber  210 . To increase the thermal capacity of the heat sink  220 , one or more fluid channels  221  may be disposed within the heat sink  220 . Outside the heat sink  220  may be a fluid source  223  and a pump  222  to continuously pass fluid through the fluid channels  221  within the heat sink  220 . The fluid may be any suitable fluid, including gasses or liquids. For example, in some embodiments, water is used due to its high specific heat. However, other fluids may also be used, including, but not limited to, oils, engineered heat transfer fluids (such as, for example, fluorinert™, Galden™, any of the Novec™ fluids, or other suitable fluids), hydrocarbons, fluorocarbons, alcohols, or others. The use of water, for example, may allow the heat sink  220  to be maintained at any temperature between 0° and 100° C., or higher if steam is utilized. The temperature of the heat sink  220  may be controlled using open loop control, wherein the flow rate of the fluid through the fluid channels  221  is maintained at a predetermined level. This level may be constant, or may be determined based on the energy supplied to the filament  212 . In another embodiment, the temperature of the heat sink  220  may be controlled using closed loop control. In this embodiment, a temperature sensor (not shown) may be installed on or near the heat sink  220 , or on or near the ion source chamber  210 , so as to monitor its temperature. The temperature sensor may be in communication with a controller, which receives the input from the temperature sensor and varies the flow through the fluid channels  221  by modulating the pump  222 . 
         [0024]    Disposed between the ion source chamber  210  and the heat sink  220  is a gas fillable chamber  230 . This gas fillable chamber comprises sidewalls  231  that connect between the ion source chamber  210  and the heat sink  220 . This connection could be made in a number of ways, including welding or brazing; a bolted connection with a high temperature seal; or may be made from a solid piece, either machined or 3-D printed. These sidewalls  231  may be constructed of a material having a very low thermal conductivity, such as ceramic, titanium, or another suitable material. In some embodiments, the sidewalls  231  are shaped so as to increase their length, thereby further lowering their thermal conductivity. For example, the sidewalls  231  may be accordion or baffle shaped. In some embodiments, the sidewalls  231  may be made extremely thin, such as less than 1 mm. This thinness further lowers the heat transfer of these sidewalls  231 . These features of the sidewalls  231  are all intended to minimize the conduction of heat from the ion source chamber  210  to the heat sink  220 , through the sidewalls  231 . 
         [0025]    In some embodiments, one or more ports  232  may be disposed in the sidewalls  231  of the gas fillable chamber  230 . For example, at least one port may be a gas inlet port  232   a,  where a gas is pumped into the gas fillable chamber  230 . A second port may be a vacuum port  232   b  to exhaust gas from within the gas fillable chamber  230 . In some embodiments, a single port  232  might be used for both inlet and exhaust. The gas inlet port  232   a  may be in communication with a gas source  240 , which supplies the gas used to fill the gas fillable chamber  230 . The vacuum port  232   b  may be in communication with a vacuum pump  250 , used to evacuate the gas fillable chamber  230 . It is noted that while one vacuum pump  250  is shown, multiple pumps may be used if necessary to achieve the required internal pressures in the gas fillable chamber  230 . In this way, the gas fillable chamber  230  may be maintained at any desired pressure. A controller  260  may be in communication with both the gas source  240  and the vacuum pump  250  to regulate the pressure within the gas fillable chamber  230 . 
         [0026]    In some embodiments, the first endwall  235  of the gas fillable chamber  230  is part of the ion source chamber  210 . In other words, the sidewalls  231  are affixed directly to one side of the ion source chamber  210 , and this side of the ion source chamber  210  serves as first endwall  235 . In another embodiment, the first endwall  235  may be constructed of a thermally conductive material, such as copper, tungsten or aluminum. This first endwall  235  is then placed in thermal communication with the ion source chamber  210 . This may be done using a thermal adhesive or paste, a deformable or compressible thermally conductive sheet, an additional gas or liquid layer, or any other means known in the art. 
         [0027]    In some embodiments, the second endwall  238  of the gas fillable chamber  230  is part of the heat sink  220 . In other words, the sidewalls  231  may be affixed directly to one side or surface of the heat sink  220 , and this side of the heat sink  220  serves as second endwall  235 . In another embodiment, the second endwall  238  may be constructed of a thermally conductive material. In this embodiment, the second endwall  238  may be thermally affixed to the heat sink  220 , such as through the use of thermal adhesive adhesive or paste, a deformable or compressible thermally conductive sheet, an additional gas or liquid layer, or any other means known in the art. 
         [0028]    Although ports  232  were previously described as being disposed in the sidewalls  231 , other embodiments are possible. For example, in another embodiment, shown in  FIG. 3 , these ports  232  may be disposed in the heat sink  220 . In  FIG. 3 , the ports  232  are connected through the heat sink  220 . Other components are as described with respect to  FIG. 2  and therefore will not be described again. In  FIG. 3 , the gas inlet port  232   a  and vacuum port  232   b  may be disposed on the second endwall  238 , which is in communication with the interior of the gas fillable chamber  230 . In this embodiment, a second set of ports  239   a ,  239   b  are disposed on a second surface of the heat sink  220  and is in communication with the gas inlet  232   a  and vacuum port  232   b,  respectively. In this embodiment, the gas source  240  is in communication with port  239   a,  while the vacuum pump  250  is in communication with port  239   b.  Gas passes from the gas source  240 , to the port  239   a,  through a first passageway  228  in the heat sink  220  and to the gas inlet  232   a.  Likewise, gas within the gas fillable chamber  230  can be exhausted by drawing it through the vacuum port  232   b,  through a second passageway  229  in the heat sink  220  to port  239   b.  In some embodiments, such as is shown in  FIG. 7 , these two ports  239   a,    239   b  may be the same port  239 . In this embodiment, a single passageway  228  exists in the heat sink  220 , terminating at port  232 . A gas source  240  and a vacuum pump  250  may be plumbed appropriately externally to the gas fillable chamber  230 , such as using a T-connection  280  and associated valves (not shown). In some cases, this may be done due to physical space limits. 
         [0029]    In yet another embodiment, the ports  232 ,  239  may be disposed on the ion source chamber  210  proximate the first endwall  235 . In this embodiment, the gas source  240  and vacuum pump  250  are in communication with ports  239   a,    239   b , respectively, which are disposed on another surface of the ion source chamber  210 . 
         [0030]    In some embodiments, the distance between the ion source chamber  210  and the heat sink  220  may be about 1 millimeter, although other separation distances are also possible. 
         [0031]    The gas source  240  may contain any suitable gas. In some embodiments, a gas having a fairly high specific heat capacity or a fairly high thermal conductivity is used. For example, in some embodiments, helium, hydrogen, argon, nitrogen, sulphur hexafluoride, nitrous oxide or steam may be used, although other gasses may also be utilized. 
         [0032]    The gas in the gas fillable chamber  230  can be maintained at any desired pressure, such as between  10  milliTorr and  760  Torr (or even a broader range). The heat transfer coefficient of the gas varies with pressure, as shown in  FIG. 4 .  FIG. 4  shows the heat transfer coefficient as a function of the pressure. This graph shows the heat transfer coefficient of helium in a one millimeter gap. However, other gasses show similar trends. Based on  FIG. 4 , it is clear that more heat can be transferred from the ion source chamber  210  to the heat sink  220  when the pressure in the gas fillable chamber  230  is high. Similar, the amount of heat transferred is low when the pressure within the gas fillable chamber  230  is low. As shown in  FIG. 4 , the heat transfer coefficient can vary by 4 orders of magnitude as the pressure varies from 0.00001 Torr to 1 Torr. Thus, the magnitude of heat transfer between the ion source chamber  210  and the heat sink  220  can be regulated by varying the pressure within the gas fillable chamber  230 . If the sidewalls  231  are poor thermal conductors, then the gas within the gas fillable chamber  230  may be the primary heat transfer mechanism between the ion source chamber  210  and the heat sink  220 . 
         [0033]    Thus, since the heat transfer coefficient of the gas fillable chamber  230  can be controlled, the temperature of the ion source chamber  210  can likewise be controlled. 
         [0034]    To better understand this phenomenon, in steady state, consider that an amount of power, P applied  is applied to the ion generator in the ion source chamber  210 , through the various source power supplies, to create the plasma. This power is dissipated in various ways. First, some power, P sidewall , is transferred by conduction through the sidewalls  231  from the ion source chamber  210  to the heat sink  220 . Second, some power, P gas , is transferred by the gas in the gas fillable chamber  230  from the ion source chamber  210  to the heat sink  220 . Third, some power, P bottom , is transferred through the bottom of the ion source chamber  210 , from the first endwall  235  to the second endwall  238  through radiation. The first endwall  235  and the second endwall  238  might be treated in some way to lower their emissivities, to reduce the radiated heat transfer between these two surfaces. This lost heat is referred to as P bottom . Fourth, some power, P rad , is transferred, also via radiation, through the other sides of the ion source chamber  210 . 
         [0035]    Several of these power dissipation paths, specifically P bottom , P sidewall  and P rad , are relatively predictable as a function of the power applied (P applied ) to the filament  212 . However, one heat dissipation path, P gas , can be varied by regulating the pressure within the gas fillable chamber  230 . Changing the gas pressure changes the power loss, P gas . This, in turn, changes the total power loss, and thus changes the steady state temperature of the ion source chamber  210 . For example,  FIG. 5  shows a first graph, where the gas in the gas fillable chamber  230  is maintained at about 1 atm. Line  400  represents the power applied to the filament  212  (P applied ), while lines  401 ,  402  and  403 , represent P bottom , P sidewall  and P rad , respectively. As can be seen, line  401  shows that as more power is applied to the ion generator in the ion source chamber  210 , the heat dissipated by the bottom of the ion source chamber  201  that is not conducted by the gas filled chamber  230  increases slightly. However, the bottom of the ion source chamber  201  is only able to dissipate about 400 W, even when the ion source chamber  210  is at 1000° C. Similarly, if the sidewalls  231  are thermally non-conductive, as described above, the total power dissipated through these sidewalls, P sidewall  as shown in line  402 , is only about 500 W, even when the ion source chamber  210  is at 1000° C. In addition, the radiation from the other sides of the ion source chamber  210 , P rad , as seen in line  403 , reaches about 1500 W when the ion source chamber  210  reaches 1000° C. The power transferred by the gas in the gas filled chamber  230  is represented by line  404 . As seen in  FIG. 5 , when the ion source chamber  210  is at 1000° C., about 1300 W are dissipated via the gas in the gas filled chamber  230 . These heat dissipation paths, specifically  401 ,  402 ,  403 , and  404 , all serve to reduce the temperature of the ion source chamber  210  by dissipating different amounts of power. In this example, if 2500 W is used to heat the filament  212 , the ion source chamber  210  may reach about 800° C., as shown by line  400 . Similarly, if 1000 W is used to heat the filament  212 , the ion source chamber  210  may reach about 500° C. 
         [0036]      FIG. 6  shows a second graph, in which the gas in the gas fillable chamber  230  is maintained at about 10 milliTorr. The lines on the graph are as described with respect to  FIG. 5 . Note that the lines  401 ,  402 ,  403  are unchanged from  FIG. 5 . This is because these heat conduction paths are unaffected by the amount of gas in the gas filled chamber  230 . However, line  404  is changed significantly because the decrease in pressure in the gas filled chamber. In this graph, almost no heat is conducted by the gas (P gas ), regardless of the temperature of the ion source chamber  210 . Thus, the heat that was previously removed by the gas in  FIG. 5  now remains in the ion source  210 . Thus, the temperature of the ion source chamber  210  is higher at a particular power level than it was in the configuration shown in  FIG. 5 . For example, if 2500 W is used to power the ion generator, the ion source chamber  210  may reach about 1000° C., as shown by line  400 . Similarly, if 1000 W is used to power the ion generator, the ion source chamber  210  may reach about 700° C. In other words, in this example, for a given input power, the temperature of the ion source chamber can be varied by about 200° C., depending on the pressure of the gas within the gas filled chamber  230 . 
         [0037]    Stated differently, assume that, to produce the desired ion species, the temperature of the ion source chamber  210  cannot exceed, for example, 700° C. When there is almost no gas in the gas filled chamber  230  (which may approximate current ion sources), about 1000 W may be applied to the ion generator, as seen in  FIG. 6 . However, by maintaining about 1 atm in the gas filled chamber  230 , about 1700 W may be applied to the ion generator, while keeping the ion source chamber  210  at 700° C., as shown in  FIG. 5 . 
         [0038]    In another embodiment, different ion species can be generated using the same applied power (P applied ) by regulating the amount of gas in the gas filled chamber  230 . For example, the pressure with the gas filled chamber  230  may be maintained at 1 atm to generate larger or molecular ions at a given P applied . By reducing the pressure with the gas filled chamber  230  to a lower value, such as 10 millitorr, smaller or atomic ions may be created using the same P applied . As an example, to create molecular ions, such as BF 2   +  or borane, it may be desirable to maintain a lower temperature of the ion source chamber  210 . However, for source gasses, such as phosphine and arsine, it may be desirable to maintain a high temperature in the ion source chamber  210  to facilitate the formation of multi-charged atomic ions. 
         [0039]    The gas filled chamber  230  may also allow the ion source chamber  210  to reach steady state temperature more quickly, thereby increasing the operational uptime of the system. This may reduce ion beam tune time. For example, during normal operation, the ion source chamber  210  may need to be at or above a certain temperature. To reach this temperature quickly, the pressure within the gas filled chamber  230  may be kept very low. Once the desired temperature is reached, gas is pumped into the gas filled chamber  230 , thereby maintaining the ion source chamber  210  at the desired temperature. 
         [0040]    The pressure within the gas filled chamber  230  may be controlled in a number of ways. 
         [0041]    In one embodiment, open loop control may be used. Empirical testing may be done to determine the appropriate pressure for each combination of feed gas, desired ion species, and applied power (P applied ). In this embodiment, the controller  260  may include a table or algorithm that utilizes feed gas, desired ion species and P applied  as inputs, and determines the required pressure in the gas filled chamber  230 . 
         [0042]    In another embodiment, closed loop control may be used. For example, in one embodiment, a temperature sensor (not shown) may be disposed on the ion source chamber  210 . The controller  260  uses the information concerning the feed gas and desired ion species to determine a desired temperature for the ion source chamber  210 . The controller  260  then uses the input from the temperature sensor to regulate the pressure within the gas filled chamber  230  to maintain this desired temperature. As described above, the pressure within the gas filled chamber  230  may be maintained by the controller  260  through adjustment of the gas source  240  and vacuum pump  250 . In some embodiments, in addition to regulating the pressure within the gas fillable chamber  230 , the controller  260  may also regulate the temperature of the heat sink  220 , as described above. 
         [0043]    In another embodiment, the controller  260  may use a parameter associated with the ion beam to regulate the pressure within the gas filled chamber  230 . An ion beam detector (not shown) may be utilized to measure a parameter associated with the ion beam extracted from the ion source chamber  210 . For example, the ion content of the beam extracted from the ion source  200  may be determined by the ion beam detector. This ion content can then be analyzed by the controller  260  to regulate the pressure in the gas filled chamber  230 . For example, if the extracted ion beam contains a large number of atomic boron ions, and BF 2   +  ions are desired, the controller  260  may increase the pressure in the gas filled chamber  230  to reduce the temperature of the ion source chamber  210 . Conversely, if more molecular ions are being extracted than desired, the controller  260  may decrease the pressure in the gas filled chamber  230  to increase the temperature of the ion source chamber  210 . In another embodiment, the ion beam current may be monitored by the ion beam detector and the power applied to the ion generator in the ion source may be varied based on the monitored ion beam current. In yet a further embodiment, both ion beam current and ion beam composition are monitored, and both applied power and pressure are varied in response to the monitored parameters. Other parameters of the ion beam that may be monitored include, but are not limited to, ion beam current density, ion beam angle and angle distribution 
         [0044]    Thus, the present disclosure describes a system and method of regulating the temperature of an ion source by transferring a variable amount of heat away from the ion source chamber. In some embodiments, this regulation of temperature is at least partially independent of the power applied to the ion generator in the ion source chamber. In some embodiments, the system can select a power level to be applied to the ion generator in the ion source chamber to generate the desired ion beam current. Independently, the system can select temperature to maintain the ion source chamber at to generate the desired ion species. In one particular embodiment, the system may select a pressure at which to keep the gas fillable chamber to generate the desired ion species. Thus, two different tunable parameters may be used to generate an ion beam of a desired current and ion composition. 
         [0045]    Thus, a system and method for generating an ion beam of a desired composition and beam current is disclosed. This system and method utilize two different mechanisms to control the extracted beam current and the species of ions that are generated. The mechanism for controlling extracted beam current is based on the power applied to the ion generator in the ion source chamber. The mechanism for controlling the species of ions that are generated may be temperature regulator in communication with the ion source chamber. The temperature regulator may control the amount of heat that is transferred away from the ion source chamber. A controller may be used to control the power applied to the ion generator and regulate the temperature of the ion source chamber. Both open loop and closed loop control system may be employed to maintain the desired ion beam current and composition. 
         [0046]    The present disclosure is not to be limited in scope by the specific embodiments described herein. Indeed, other various embodiments of and modifications to the present disclosure, in addition to those described herein, will be apparent to those of ordinary skill in the art from the foregoing description and accompanying drawings. Thus, such other embodiments and modifications are intended to fall within the scope of the present disclosure. Furthermore, although the present disclosure has been described herein in the context of a particular implementation in a particular environment for a particular purpose, those of ordinary skill in the art will recognize that its usefulness is not limited thereto and that the present disclosure may 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 breadth and spirit of the present disclosure as described herein.