JP2014110136A - Ion source, ion beam irradiation device, and method of cleaning ion source - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ion source capable of effectively removing deposits in the ion source in a short time when the inside of a plasma generation container or an acceleration electrode is cleaned by supplying a cleaning gas into the plasma generation container and turning the cleaning gas into plasma.SOLUTION: At a cleaning operation, a positive electrode of a bias power supply 7 is connected at an acceleration electrode 41 side, and a bias voltage is set so that an absolute value of the bias voltage at the cleaning operation is larger than an absolute value of a bias voltage at a normal operation.

Description

  The present invention relates to, for example, an ion source used in an ion beam irradiation apparatus having a cleaning function and a cleaning method thereof.

For example, an ion source used in an ion implantation apparatus includes a plasma generation container in which plasma is generated as shown in Patent Document 1, and boron trifluoride (BF ₃ ) or phosphine (PH ₃ ) in the plasma generation container. ) And the like, a filament for generating plasma by ionizing the ion source gas in the plasma generation vessel, and an opening in the vicinity of the opening of the plasma generation vessel. Some have an accelerating electrode for extracting an ion beam.

In the ion source of Patent Document 1, a bias power source is provided for applying a bias voltage, which is a voltage of the accelerating electrode with respect to the plasma generation vessel, so that more desired ion species are included in the ion beam. ing. For example, when the ion source gas is BF ₃ , a predetermined bias voltage is set with the positive electrode of the bias power source connected to the acceleration electrode side, and when the ion source gas is PH ₃ , the acceleration electrode side is set. The predetermined bias voltage is set in a state where the negative electrode of the bias power supply is connected. By doing in this way, the quantity of the boron ion or phosphorus ion contained in an ion beam can be increased.

  By the way, when such ion source gas is turned into plasma and an ion beam is repeatedly extracted from the ion source, components of the ion source gas are deposited on the inner wall of the plasma generation container or the acceleration electrode. . When this deposit exceeds a predetermined amount, the number of occurrences of abnormal discharge due to this volume increases in the plasma generation container, and it becomes impossible to stably generate plasma, and as a result, a desired ion beam is generated. I can't get it.

  Therefore, as shown in Patent Document 2, the ion source is periodically cleaned by supplying hydrogen gas as a cleaning gas in place of the ion source gas into the plasma container to generate hydrogen plasma. By this cleaning method, hydrogen ions emitted from the hydrogen plasma in the plasma generation container collide with the deposit, and the deposit is sputtered to remove the deposit deposited in the plasma generation container or the acceleration electrode. Is done.

  However, although Patent Document 2 shows that deposits can be removed by supplying hydrogen gas into the plasma generation vessel and generating hydrogen plasma, the ion source operation method during cleaning and various power sources The setting method is not described in detail.

  For example, in order to increase the number of substrates processed per unit time, there is a technical problem of making it possible to effectively remove deposits while shortening the cleaning time as much as possible. It was not well understood whether such setting and operation should be performed. Also, it is not clear how to set or operate the ion source, for example, when it is desired to remove deposits intensively for either the plasma generation vessel or the acceleration electrode. It was.

JP 2007-115511 A Japanese Patent No. 2956412

  The present invention has been made in view of the above-described problems. In cleaning the plasma generation container or the acceleration electrode by supplying the cleaning gas into the plasma generation container and converting the cleaning gas into plasma, It is an object of the present invention to provide an ion source, an ion beam irradiation apparatus, or an ion source cleaning method capable of effectively removing deposits in an ion source in a short time.

  That is, an ion source according to the present invention includes a plasma generation container in which plasma is generated, a gas supply mechanism that supplies an ion source gas or a cleaning gas into the plasma generation container, and an ion source gas in the plasma generation container. Alternatively, an ionization member that ionizes the cleaning gas to generate plasma, and an insulating electrode that is provided in the vicinity of the opening of the plasma generation container and is insulated from the plasma generation container, and for extracting an ion beam from the plasma, An arc power source for applying an arc voltage that is a voltage of the plasma generation vessel to the ionization member; and a bias power source for applying a bias voltage that is a voltage of the acceleration electrode to the plasma generation vessel, the gas supply mechanism Generates the cleaning gas during the cleaning operation An ion source configured to be supplied into a chamber, wherein a positive electrode of the bias power supply is connected to the acceleration electrode side during a cleaning operation, and an absolute value of a bias voltage during the cleaning operation is determined during a normal operation. A bias power supply control unit that controls the bias power supply so as to be larger than an absolute value of the bias voltage is provided.

  The ion source cleaning method of the present invention includes a plasma generation container in which plasma is generated, a gas supply mechanism for supplying an ion source gas or a cleaning gas into the plasma generation container, and a plasma generation container. An ionization member for generating plasma by ionizing the ion source gas or the cleaning gas, and an acceleration for extracting an ion beam from the plasma, provided in the vicinity of the opening of the plasma generation container so as to be insulated from the plasma generation container. An electrode, an arc power source for applying an arc voltage that is a voltage of the plasma generation vessel to the ionization member, and a bias power source for applying a bias voltage that is a voltage of the acceleration electrode to the plasma generation vessel, The gas supply mechanism moves the cleaning gas forward during the cleaning operation. A cleaning method used for an ion source configured to be supplied into a plasma generation container, wherein a positive electrode of the bias power source is connected to the acceleration electrode side during a cleaning operation, and a bias voltage during the cleaning operation is A bias voltage setting step is provided for setting the bias voltage so that the absolute value is larger than the absolute value of the bias voltage during normal operation.

  Here, “during normal operation” refers to an operating state in which, for example, an ion beam containing a desired type of ion species is extracted from an ion source and is irradiated onto a workpiece such as a semiconductor. “During cleaning operation” refers to an operation state in which, for example, a cleaning gas is supplied to a plasma generation container in a predetermined amount or more, and an effect of removing deposits is recognized by the cleaning gas plasma.

  If this is the case, the positive electrode of the bias power supply is connected to the acceleration electrode side during the cleaning operation, and the magnitude of the bias voltage, which is the voltage of the acceleration electrode with respect to the plasma generation vessel, is larger than that during normal operation. Since the absolute value is set to be high, the sheath voltage, which is the voltage of the cleaning gas plasma generated in the plasma generation container, with respect to the plasma generation container can be increased, and the components of the cleaning gas can be increased. Deposits deposited on the inner wall of the plasma generation vessel by ions can be sputtered with high energy. That is, since a high energy ion can be made to collide with the deposit deposited in the plasma generation container, a sufficient cleaning effect can be obtained.

  In addition, since the positive electrode of the bias power source is connected to the acceleration electrode side, for example, when a cleaning gas such as hydrogen gas or a rare gas is turned into plasma, a repulsive force is generated between the ions and the acceleration electrode. The deposit deposited mainly inside the plasma generation container is sputtered. Accordingly, it is possible to limit the target for removing the deposits to the plasma generation container, and the cleaning effect can be concentrated and more precise cleaning can be realized.

  Further, for example, compared to increasing the sheath voltage by changing the voltage applied to the ionizing member, its frequency, etc., the method of making the absolute value of the bias voltage higher during the cleaning operation than during the normal operation is Even if the voltage is not so high, the cleaning effect can be improved by increasing the sheath voltage.

  In addition, the present invention sets the bias voltage, which has been used to increase the ratio of the desired ions contained in the ion beam during normal operation, to a value different from that during normal operation during cleaning. This is the first time the inventors of the present application have found that a high cleaning effect can be obtained as a result of intensive studies. For example, the invention is not easily conceived by combining Patent Documents 1 and 2.

  As one specific configuration example in which a high cleaning effect can be obtained with respect to the deposits accumulated in the plasma generation container, the bias power supply control unit is configured such that the absolute value of the bias voltage during the cleaning operation is normal. Examples include controlling the bias power supply so that the absolute value of the bias voltage during operation is twice or more.

  As a more preferable specific configuration example in which a bias voltage for effectively removing deposits in the plasma generation container can be set, the bias power supply control unit is configured so that the bias voltage during the cleaning operation becomes 100 V or more. Any device that controls the bias power source may be used.

  In order to ensure that the plasma of the cleaning gas generated in the plasma generation vessel is continuously turned on and the deposit cleaning effect is sufficiently exhibited, the arc voltage during the cleaning operation is approximately 30 V. What is necessary is just to further include an arc power supply control unit that controls the arc power supply so as to be 100 V or less.

  If the positive electrode of the plasma electrode is connected to the acceleration electrode from the beginning during the cleaning operation, the initial discharge becomes unstable due to deposits adhering to the acceleration electrode, an overcurrent flows to the bias power source, and the protection circuit works. The power output may be turned off. If the bias power supply is turned off, restoration work or the like is required, and the time required for cleaning becomes long. In addition, it is conceivable to use a bias power supply having a large power supply capacity so as to cope with an overcurrent, but this is not preferable because it causes an increase in manufacturing cost. In order to prevent such problems from occurring, after the bias power supply control unit connects the negative electrode of the bias power supply to the acceleration electrode side during the cleaning operation, the bias power supply is connected to the acceleration electrode side. Any device may be used as long as it controls the bias power source so as to connect the positive electrode. In such a case, the accelerating electrode is first cleaned and the deposits are removed. Therefore, when the accelerating electrode is set to a positive polarity and the cleaning of the plasma generating container is started, the initial discharge is performed. It is possible to stabilize and prevent an overcurrent from flowing to the bias power source.

  Even in the case of cleaning the acceleration electrode, a sufficient potential is generated between the cleaning gas plasma and the acceleration electrode so that deposits deposited on the acceleration electrode are sputtered by high energy ions. In order to obtain a good cleaning effect, the bias power source may be controlled so that the absolute value of the bias voltage becomes 100 V or more.

  While reducing the proportion of the time during which the cleaning operation is performed in the total operation time, while increasing the number of substrates that can be processed per unit time, for example, while obtaining a sufficient cleaning effect, the production efficiency can be improved. Further includes a cleaning mode determining unit that determines whether to perform the long-time cleaning mode or the short-time cleaning mode during the cleaning operation, and the cleaning mode determination unit is configured to store deposits in the plasma generation container. If the cleaning index, which is a value related to the remaining amount, exceeds a predetermined threshold value, the long-time cleaning mode may be determined, and otherwise, the short-time cleaning mode may be determined. .

  In addition, if the ion beam irradiation apparatus is equipped with the ion source as described above, the ion source is always suitably cleaned, so that a desired ion beam can be obtained. It can be performed constantly and accurately.

  As described above, according to the ion source, the ion beam irradiation apparatus, and the ion source cleaning method of the present invention, the bias voltage that has been used to increase the amount of ion species included in the ion beam that has been conventionally extracted is used. By setting a special voltage for the cleaning operation, deposits in the ion source can be removed more suitably than in the past. More specifically, since the deposit is sputtered by the cleaning gas ions to which sufficient energy is applied by the bias voltage, the cleaning effect of the deposit can be greatly improved. Further, by connecting the positive electrode of the bias power source to the acceleration electrode side, only the deposit deposited mainly in the plasma generation container can be sputtered to ions in the plasma. That is, the present invention can clearly limit the cleaning place and concentrate the cleaning effect.

1 is a schematic overall view of an ion implantation apparatus according to a first embodiment of the present invention. The schematic diagram which shows the structure of the ion source in 1st Embodiment. The simple schematic diagram which shows the structure of the ion source at the time of the normal driving | operation of 1st Embodiment. The simple schematic diagram which shows the structure of the ion source at the time of the cleaning driving | operation of 1st Embodiment. The simple schematic diagram which shows the structure of the ion source in the modification of 1st Embodiment. The simple schematic diagram which shows the structure of the ion source at the time of the cleaning driving | operation of 2nd Embodiment. The simple schematic diagram which shows the structure of the ion source in other embodiment.

  An ion beam irradiation apparatus and an ion source 100 according to a first embodiment of the present invention will be described with reference to the drawings.

  This ion beam irradiation apparatus irradiates the surface of a substrate PL (glass substrate) for a flat panel display with an ion beam IB, implants ions into the substrate PL, and makes the characteristics of the substrate PL desired. It is the ion implantation apparatus 200 used for.

  FIG. 1 is a schematic plan view showing an ion implantation apparatus 200 according to the first embodiment. The ion implantation apparatus 200 performs mass analysis on the ion beam IB extracted from the ion source 100 by the mass analyzer 101 and then irradiates the substrate PL fixed to the substrate driving apparatus 102 with desired ions. The seed is implanted into the substrate PL. Note that the path of the ion beam IB from the ion source 100 to the substrate driving apparatus 102 is surrounded by a vacuum container (not shown), and is kept in a vacuum during ion implantation.

  The ion beam IB extracted from the ion source 100 has a width W in the Y-axis direction, which is the front and back direction in FIG. 1, in a direction perpendicular to the paper surface in FIG. This is a so-called ribbon-like ion beam IB having a sheet shape sufficiently larger than a certain thickness in the X-axis direction. Further, the substrate PL is driven in the X-axis direction or the Y-axis direction by the substrate driving device 102, and scanning is performed so as to cross the thickness direction of the ion beam IB, so that the entire surface of the substrate PL is irradiated with the ion beam IB. It is supposed to be.

  Further, the ion source 100 has at least two operation modes. The ion source 100 is deposited inside the ion source 100 by the normal operation in which the ion beam IB is drawn out to perform ion implantation on the substrate PL and the normal operation. It is possible to perform a cleaning operation for removing deposits composed of components of the ion source gas. This cleaning operation is an operation for generating a plasma P by supplying a cleaning gas and removing deposits in the ion source 100 by sputtering with ions of the cleaning gas.

  Next, details of the ion source 100 will be described.

  The ion source 100 includes a plasma generation container 1 in which plasma P is generated, a gas supply mechanism 2 for supplying an ion source gas or a cleaning gas into the plasma generation container 1, and an inside of the plasma generation container 1. 1 or a plurality of filaments 3 constituting an ionization member for generating plasma P by ionizing the ion source gas or the cleaning gas, and leading edge of the plasma generation container 1 in the vicinity of the opening 11 of the plasma generation container 1. And an accelerating electrode 41 for extracting the ion beam IB from the plasma P. Further, the ion source 100 has an arc voltage that is a voltage of the plasma generation container 1 with respect to each filament 3 as a mechanism for controlling operations such as generation and maintenance of the plasma P, extraction of the ion beam IB, or cleaning. An arc power source 6 for applying voltage, a bias power source 7 for applying a bias voltage which is a voltage of the acceleration electrode 41 to the plasma generating vessel 1, and at least the gas supply mechanism 2, the arc power source 6, and the bias power source 7 And a control mechanism 8 for controlling.

  Each part will be described in detail.

  The inside of the plasma generation container 1 is maintained at a predetermined degree of vacuum by a vacuum source (not shown), and is for maintaining the plasma P of the supplied gas inside. More specifically, as shown in FIG. 2, the plasma generation container 1 is a container having a substantially rectangular parallelepiped internal space whose long side is the Y-axis direction, and the gas supply mechanism 2 is provided on one side surface. A gas supply port 12 through which various gases are supplied is formed, and the filament 3 is attached from the atmosphere side to the plasma generation vessel 1 with the same side surface as an attachment surface. Further, the plasma generation container 1 has an opening on the side surface facing the mounting surface, and the acceleration electrode 41 is mounted on the outside in the vicinity of the opening 11 so as to block the opening. Further, a plurality of cusp magnetic fields for confining the plasma P generated near the inner wall of the plasma generation vessel 1 in the plasma generation vessel 1 are formed on the atmosphere side of each side surface and end surface of the plasma generation vessel 1. The magnet 5 is arranged to constitute a so-called bucket-side ion source. The magnet 5 may be a permanent magnet or an electromagnet.

The gas supply mechanism 2 is connected to the gas supply port 12 of the plasma generation container 1 and supplies an ion source gas or a cleaning gas into the plasma generation container 1. The gas supply mechanism 2 includes, for example, one of a first bottle in which an ion source gas is sealed and a second bottle in which a cleaning gas is sealed based on an operation switching command from a control mechanism 8 described later, and the gas supply. The port 12 is connected. More specifically, the first bottle filled with the ion source gas and the gas supply port 12 are connected during normal operation, and the second bottle filled with the cleaning gas and the gas supply port 12 during cleaning operation. Is connected. The ion source gas is changed according to the ion species to be implanted. For example, BF ₃ (boron trifluoride) gas is used when boron is implanted, and PH is implanted when phosphorus is implanted. ₃ (phosphine) gas is used. Meanwhile, hydrogen gas and various rare gases are used as the cleaning gas.

  The acceleration electrode 41 is a substantially flat metal plate having a large number of holes or slits, and is arranged in the vicinity of the outside of the opening 11 so as to close the opening 11 of the plasma generating vessel 1 as shown in FIG. It is provided. The accelerating electrode 41 constitutes a lead electrode system 4 together with a flat lead electrode 42, a suppression electrode 43, and a ground electrode 44 that are sequentially provided on the outer side. The electrodes constituting the extraction electrode system 4 are attached so that the end portions of the electrodes are supported by the insulator Z from the plasma generation vessel 1 so that the voltages of the electrodes can be controlled independently. . Further, the polarity of the bias power source connected to the accelerating electrode 41 is changed according to the type of ions to be ion-implanted during normal operation, and a voltage different from that during normal operation is applied during the cleaning operation. It will be. This will be described in detail in the bias power supply control unit 83 described later.

  The arc power source 6 is a variable voltage power source and is provided so that the polarity on the filament 3 side is negative and the polarity on the plasma generation vessel 1 side is positive. By setting the arc voltage, which is a voltage applied by the arc power source 6, to a predetermined value, the plasma P generated in the plasma generating vessel 1 can be stably turned on.

  The bias power source 7 is also a variable voltage power source and can be changed in its polarity. By changing the voltage applied by the bias power supply 7, more ions are extracted as the ion beam IB during normal operation, and in the cleaning operation, the region to be cleaned is limited, The deposit is removed more effectively.

  The control mechanism 8 is a so-called computer including, for example, a CPU, a memory, input / output means, and the like, and executes at least a gas supply mechanism control unit 81, an arc power supply control unit 82, by executing a program stored in the memory. The function as the bias power supply control unit 83 is exhibited. In addition, regarding the description regarding the voltage of each following power supply, it is the schematic diagram which simplifiedly represented FIG. 2, and the plasma production | generation container 1, the filament 3, the acceleration electrode 41, the arc power supply 6, and the bias power supply 7 which are especially related to this invention This will be described with reference to FIGS.

  The gas supply mechanism control unit 81 is configured to supply the ion source gas from the gas supply mechanism 2 at a predetermined flow rate during normal operation and to supply the cleaning gas at a predetermined flow rate during cleaning operation.

  The arc power supply control unit 82 controls the arc voltage to an appropriate value by the arc power supply 6 for each operation mode and the type of ion source gas or cleaning gas used. For example, the arc power supply controller 82 controls the arc power supply 6 so that 120V is applied as an arc voltage as shown in FIG. 3 during normal operation. Further, the arc power control unit 82 is configured so that the plasma P of the cleaning gas is stably lit as shown in FIG. 4 when hydrogen gas is used as the cleaning gas during the cleaning operation as shown in FIG. The arc power supply 6 is controlled so that a voltage of 30V to 100V is applied as the arc voltage.

The bias power supply control unit 83 also controls the bias power supply 7 in an appropriate state for each operation mode and the type of ion source gas or cleaning gas used. More specifically, when the BF ₃ is used as the ion source gas during normal operation, the bias power source control unit 83 has the bias power source 7 on the plasma generation vessel 1 side as shown in FIG. The bias power supply 7 is controlled so that a bias voltage is applied by connecting the positive electrode of the bias power supply 7 to the acceleration electrode 41 side and a bias voltage of 15 V is applied. When PH ₃ is used as an ion source gas during normal operation, the positive electrode of the bias power source 7 is connected to the plasma generation container 1 side, and the negative electrode of the bias power source 7 is connected to the acceleration electrode 41 side. The bias power supply control unit 83 is configured so as to apply a bias voltage by connecting them. In this way, the bias power supply control unit 83 changes the polarity of the bias power supply 7 according to the type of ion source gas during normal operation, and ions are efficiently extracted as the ion beam IB for each type of gas. The bias power supply 7 is controlled to apply the absolute value voltage as a bias voltage.

Next, the configuration and operation of the bias power supply controller 83 during the cleaning operation will be described. The bias power supply control unit 83 connects the positive electrode of the bias power supply 7 to the acceleration electrode 41 side, particularly when the purpose is to remove deposits in the plasma generation vessel 1 during the cleaning operation. In addition, the bias power source 7 is controlled so that the absolute value of the bias voltage during the cleaning operation is larger than the absolute value of the bias voltage during the normal operation. That is, in the first embodiment, when the ion source gas is BF ₃ , the bias power supply controller 83 is configured to apply a voltage having an absolute value larger than 15 V as a bias voltage during the cleaning operation.

  More specifically, the bias power supply control unit 83 controls the bias power supply so that the absolute value of the bias voltage during the cleaning operation is at least twice the absolute value of the bias voltage during the normal operation, more preferably 100 V or more. 7 is controlled. In the first embodiment, as shown in FIG. 4, the bias power supply control unit 83 is configured to apply 120V, which is a voltage of 100V or more, as a bias voltage.

  As described above, during the cleaning operation, the positive electrode of the bias power source 7 is connected to the acceleration electrode 41 side, and the cleaning effect is improved by applying a voltage having a larger absolute value as the bias voltage than during the normal operation. Qualitative explanation.

  As shown in FIG. 4, when a bias voltage of 120 V is applied to the acceleration electrode 41 during the cleaning operation, the acceleration electrode 41 is in a high potential state with respect to the plasma generation vessel 1. Become. Therefore, the sheath voltage, which is the voltage of the plasma P of the cleaning gas with respect to the plasma generation vessel 1, also increases with the potential of the acceleration electrode 41. In other words, as shown in FIG. 4, the sheath voltage is pulled up to a predetermined value up to 120 V which is the potential of the acceleration voltage, and is in a high potential state. Therefore, since the sheath voltage between the plasma P and the plasma generation container 1 is in a high state, the hydrogen ions in the plasma P of the cleaning gas are deposited in the plasma generation container 1 in a high energy state. Can be sputtered. In other words, since the high-energy hydrogen ions collide with the deposit attached in the plasma generation container 1, the deposit is effectively removed. In addition, it is considered that the discharge easily occurs between the accelerating electrode 41 and the plasma generation vessel 1 also contributes to the generation of the cleaning gas plasma P in a high energy state and enhances the cleaning effect. It is done.

  As described above, according to the ion source 100 and the ion implantation apparatus 200 of the first embodiment, when the ion beam IB is extracted during normal operation, adjustment is appropriately performed to increase the number of ion species included in the ion beam IB. As for the bias voltage, a higher positive voltage is applied to the accelerating electrode 41 during the cleaning operation than during the normal operation. Therefore, the sheath voltage is increased and the deposits of cleaning gas ions are increased. The cleaning energy can be increased by increasing the collision energy against the.

  In addition, since the acceleration electrode 41 is in a high potential state with respect to the plasma generation container 1, most of the ions sputter deposits deposited on the plasma generation container 1. The cleaning effect can be enhanced by concentrating substantially on the plasma generation vessel 1. Further, since cleaning can be performed by clearly limiting the cleaning portion in the ion source 100 as described above, for example, an appropriate cleaning time is set for each portion of the ion source 100 according to the amount of deposits. This makes it possible to perform a more preferable cleaning operation.

  Further, during the cleaning operation, the arc power source control unit 82 controls the arc power source 6 so as to maintain the arc voltage at 30V to 100V. Therefore, the cleaning gas plasma P is stably lit and the cleaning operation is in progress. In addition, the collision of ions with the deposit is not interrupted, and the cleaning can be completed in a short time.

  For these reasons, the ion implantation apparatus 200 of the present invention has a high cleaning effect on the deposits in the ion source 1, can always obtain a desired ion beam IB, and takes a short time for the cleaning operation. Therefore, the number of substrates PL processed per unit time can be increased while performing ion implantation with stable accuracy.

  A modification of the first embodiment will be described with reference to FIG.

  Since the bias power supply 7 shown in FIGS. 3 and 4 is a variable voltage power supply, the absolute value of the bias voltage is changed only by the bias power supply 7 during normal operation and cleaning operation. In order to connect a positive electrode of the bias power source 7 to the acceleration voltage 41 side during the cleaning operation even with a fixed voltage power source and to apply a higher voltage than during the normal operation, the arc power source as shown in FIG. 6 may be provided with a switching circuit 71 that serves as the plasma generation container 1 during the normal operation and serves as the acceleration electrode 41 during the cleaning operation.

  Even in such a case, it is possible to increase the bias voltage applied to the acceleration electrode 41 only at the time of cleaning, thereby enhancing the cleaning effect. In addition, with such a circuit configuration, reconnection can be simplified.

  Next, a second embodiment of the present invention will be described with reference to FIG. In the description of the second embodiment, the same or corresponding members as those in the first embodiment are denoted by the same reference numerals.

  The ion source 100 of the second embodiment is different from the first embodiment in that the configuration of the bias power supply control unit 83 is further added.

  More specifically, the bias power supply control unit 83 of the second embodiment performs the cleaning operation as shown in FIG. 6 so that the plasma generation container 1 is cleaned first after the acceleration electrode 41 is cleaned. First, the bias power supply 7 is controlled so that the negative electrode of the bias power supply 7 is connected to the acceleration electrode 41 side, and the positive electrode of the bias power supply 7 is connected to the acceleration electrode 41 side after a predetermined time has elapsed. Is to control. Further, during the cleaning operation, while the negative electrode of the bias power supply 7 is connected to the acceleration electrode 41 side, the bias power supply control unit 83 controls the bias power supply so that the absolute value of the bias voltage becomes 100 V or more. 7 is controlled. Specifically, in the second embodiment, the absolute value of the bias voltage is 120 V, and control is performed so that the negative electrode of the bias power supply 7 is connected to the acceleration electrode 41 side. When the bias voltage is controlled in this way, the sheath voltage rises only to about 10V, but the voltage of the plasma P with respect to the acceleration electrode 41 is opposite to the description of the first embodiment, and the upper limit is 120V. Will be enhanced. Accordingly, the high energy ions sputter the deposits deposited on the acceleration electrode 4, and the deposits deposited on the acceleration electrode 41 are preferably removed.

  As described above, according to the ion source 100 and the ion implantation apparatus 200 of the second embodiment, the bias power supply controller 83 first connects the negative electrode of the bias power supply 7 to the acceleration electrode 41 side during the cleaning operation. Since the bias power source 7 is controlled so that the absolute value of the bias voltage is larger than that during normal operation, deposits can be suitably removed by concentrating on the acceleration electrode 41. Then, after the cleaning of the acceleration electrode 41 is completed, the positive electrode of the bias power source 7 is connected to the acceleration electrode 41, and the cleaning of the plasma generation container 1 is started, so that the stability of the initial discharge is improved. It is possible to prevent overcurrent from flowing to the bias power source 7. Therefore, the protection circuit of the bias power supply 7 operates, the power supply output is turned off, and it takes a long time to recover, so that the problem that the cleaning time becomes long can be prevented. Further, since it is possible to prevent overcurrent from flowing to the bias power source 7 due to abnormal discharge during the cleaning operation, it is not necessary to use a large power source capacity as the bias power source 7 and manufacturing costs can be reduced. .

  Other embodiments will be described.

  As shown in FIG. 7, the bias power source 7 may be an AC power source, and the pole of the bias power source 7 connected to the acceleration electrode 41 may be changed every predetermined time during the cleaning operation. That is, the cleaning of the acceleration electrode 41 and the cleaning of the plasma generation container 1 may be alternately performed during the cleaning operation. In this embodiment, as shown in FIG. 7, a voltage of −120 V to 120 V is applied as the bias voltage, and the sheath voltage changes according to the change of the bias voltage. Specifically, when a bias voltage of −120 V is applied, the sheath voltage is lowered to a predetermined voltage with −120 V being the lower limit, and when a bias voltage of 120 V is applied, the sheath voltage is decreased. As in the case of FIG. 4, the voltage is raised to a predetermined voltage with 120V as the upper limit.

  The arc voltage and the bias voltage shown in each of the embodiments are examples and are not limited to the values shown. For example, when it is desired to clean the plasma generation container, the positive electrode of the bias power source is connected to the acceleration electrode regardless of the type of ion source gas used during normal operation, and the bias voltage during cleaning operation is used. If the absolute value of is set to be larger than the absolute value of the bias voltage during normal operation, the cleaning effect can be enhanced.

  Further, in each of the embodiments, by devising the absolute value of the bias voltage and the applied voltage of the bias power source connected to the acceleration electrode 41 side during the cleaning operation, either the ion source 1 or the acceleration electrode 41 is changed. Although the cleaning effect can be enhanced by intensive cleaning, a remarkable cleaning effect can be obtained as in the above-described embodiment by changing the voltage applied to the other electrodes constituting the extraction electrode system 4. it can.

  That is, any one of the electrodes constituting the extraction electrode system 4 during the cleaning operation is used as a voltage change target electrode to which a voltage different from that during the normal operation is applied, and the positive electrode of the power source is connected to the voltage change target electrode A voltage higher than the value may be applied, and the voltage may be higher than the voltage applied to the electrode disposed on the plasma generation container 1 side relative to the voltage change target electrode. Here, the predetermined value or higher is, for example, a voltage of 100 V or higher.

  For example, a positive electrode of a power source may be connected to the extraction electrode 42 side during a cleaning operation, and a voltage applied to the extraction electrode 42 may be higher than that of the plasma generation vessel 1 and the acceleration electrode 41. In such a case, a cleaning effect higher than the conventional one can be obtained while the cleaning portion is both the inner wall of the plasma generation container 1 and the acceleration electrode 41. As another example, a positive electrode of a power source is connected to the suppression electrode 43 side during a cleaning operation, and a voltage higher than a predetermined value is applied, and the voltage applied to the suppression electrode 43 is the plasma generation. The thing which is applying the voltage higher than the container 1, the acceleration electrode 41, and the extraction electrode 42 is mentioned. Even in such a case, a high cleaning effect can be obtained while the cleaning portion is both the inner wall of the plasma generation container 1 and the acceleration electrode 41. Further, when a voltage is applied as described above, it is possible to remove deposits deposited on the back side of the accelerating electrode 41 (the surface opposite to the plasma generation container 1).

  Further, in order to reduce the ratio of the cleaning operation time in the total operation time as much as possible while keeping the properties of the extracted ion beam as desired, in order to improve the ion implantation and product production efficiency, the control mechanism includes: A cleaning mode determination unit that determines whether to perform a long-time cleaning mode or a short-time cleaning mode during a cleaning operation, and the cleaning mode determination unit determines the remaining amount of deposits in the plasma generation container. It may be configured to determine the long-time cleaning mode when the cleaning index, which is a related value, exceeds a predetermined threshold value, and to determine the short-time cleaning mode otherwise.

  That is, the cleaning mode determination unit as described above continuously produces a rough short-time cleaning mode in which deposits remain minutely in the ion source while the properties of the ion beam are not significantly affected. Efficiency can be improved. Then, the amount of deposits becomes too large, abnormal discharges etc. occur frequently, and the deposits in the ion source are almost completely cleaned by performing a complete long-time cleaning immediately before it becomes impossible to maintain the properties of the ion beam. The quality can also be maintained.

  Examples of the cleaning index that is a value related to the remaining amount of deposit monitored by the cleaning mode determination unit include the number of processed substrates and the number of discharges in the ion source.

  More specifically, in the short-time cleaning, the amount of deposits in the ion source increases as the number of processed substrates increases. The cleaning mode determination unit may be configured so that cleaning is executed for each lot for a short time, and cleaning is executed for a long time when a threshold number of substrate processing sheets or a predetermined number of lots is exceeded. Note that after the cleaning is performed for a long time, the count of the number of processed substrates is reset, and thereafter the same operation may be repeated.

  A cleaning index that can reflect the amount of deposits more than the number of processed substrates includes the number of discharges in the ion source. This cleaning index uses the fact that the frequency of occurrence of abnormal discharge in the ion source increases as the deposit increases. For the detection of abnormal discharge, for example, the voltage value of the arc power supply or bias power supply may be monitored, and the cleaning mode determination unit may be configured to count as discharge when the value changes abruptly.

  If this is the case, the state related to the amount of deposits in the ion source can be grasped more accurately, so that the cleaning can be repeated for a short time until the last minute, reducing the time for the cleaning operation and improving the production efficiency. Easy to improve.

  The ion source of the present invention can be used in various devices as long as it is an apparatus that extracts and uses an ion beam. That is, the ion beam irradiation apparatus of the present invention is a concept including various applications such as an ion beam implantation apparatus, an ion doping apparatus, an ion beam deposition apparatus, and an ion beam etching apparatus. The substrate irradiated with the ion beam is not limited to a semiconductor substrate, and may be a silicon wafer, a glass substrate, or the like.

  In addition, various modifications and combinations of embodiments may be performed without departing from the spirit of the present invention.

200: Ion implantation apparatus (ion beam irradiation apparatus)
DESCRIPTION OF SYMBOLS 100: Ion source 1: Plasma generation container 11: Opening part 12: Gas supply port 2: Gas supply mechanism 3: Filament 4: Extraction electrode system 41: Acceleration electrode 42: Extraction electrode 43: Suppression electrode 44: Ground electrode 5: Magnet 6: Arc power source 7: Bias power source 8: Control mechanism 81: Gas supply mechanism control unit 82: Arc power source control unit 83: Bias power source control unit 101: Mass analyzer 102: Substrate driving device PL: Substrate P: Plasma

Claims (9)

A plasma generation container in which plasma is generated inside, a gas supply mechanism for supplying ion source gas or cleaning gas into the plasma generation container, and ion source gas or cleaning gas in the plasma generation container are ionized to generate plasma. An ionizing member to be generated, provided in the vicinity of the plasma generating vessel in the vicinity of the plasma generating vessel, an accelerating electrode for extracting an ion beam from the plasma, and the plasma generating vessel with respect to the ionizing member An arc power source for applying an arc voltage that is a voltage; and a bias power source for applying a bias voltage that is a voltage of the accelerating electrode with respect to the plasma generation vessel, and the gas supply mechanism supplies the cleaning gas to the plasma during a cleaning operation. Configured to feed into the production vessel An ion source,
During the cleaning operation, the positive electrode of the bias power supply is connected to the acceleration electrode side, and the bias power supply is controlled so that the absolute value of the bias voltage during the cleaning operation is larger than the absolute value of the bias voltage during the normal operation. An ion source comprising a bias power supply controller for performing the operation.   2. The ion source according to claim 1, wherein the bias power source control unit controls the bias power source so that an absolute value of a bias voltage during a cleaning operation is twice or more of an absolute value of a bias voltage during a normal operation.   The ion source according to claim 1 or 2, wherein the bias power supply control unit controls the bias power supply so that a bias voltage during a cleaning operation is 100 V or more.   The ion source according to any one of claims 1 to 3, further comprising an arc power source controller that controls the arc power source so that an arc voltage during a cleaning operation is 30 V or more and 100 V or less.   The bias power controller controls the positive electrode of the bias power source to be connected to the acceleration electrode side after the negative electrode of the bias power source is connected to the acceleration electrode side during the cleaning operation. An ion source according to the above.   The bias power supply control unit controls the bias power supply so that an absolute value of the bias voltage becomes 100 V or more while connecting a negative electrode of the bias power supply to the acceleration electrode side during a cleaning operation. Ion source. A cleaning mode determination unit that determines whether to perform the long-time cleaning mode or the short-time cleaning mode during the cleaning operation;
The cleaning mode determination unit determines the cleaning mode for a long time when the cleaning index, which is a value related to the remaining amount of deposits in the plasma generation container, exceeds a predetermined threshold, and otherwise 7. The ion source according to claim 1, wherein the ion source is configured to determine a short time cleaning mode.   An ion beam irradiation apparatus comprising the ion source according to claim 1. A plasma generation container in which plasma is generated inside, a gas supply mechanism for supplying ion source gas or cleaning gas into the plasma generation container, and ion source gas or cleaning gas in the plasma generation container are ionized to generate plasma. An ionizing member to be generated, provided in the vicinity of the plasma generating vessel in the vicinity of the plasma generating vessel, an accelerating electrode for extracting an ion beam from the plasma, and the plasma generating vessel with respect to the ionizing member An arc power source for applying an arc voltage that is a voltage; and a bias power source for applying a bias voltage that is a voltage of the accelerating electrode with respect to the plasma generation vessel, and the gas supply mechanism supplies the cleaning gas to the plasma during a cleaning operation. Configured to feed into the production vessel A cleaning method for use in an ion source,
During the cleaning operation, the positive electrode of the bias power supply is connected to the acceleration electrode side, and the bias voltage is set so that the absolute value of the bias voltage during the cleaning operation is larger than the absolute value of the bias voltage during the normal operation. An ion source cleaning method comprising a bias voltage setting step.