Patent Application
20240030004
This Application is based on and claims priority to Japanese Application No. 2022-114899, filed on Jul. 19, 2022, in the Japan Patent Office, the contents of which being incorporated by reference herein in its entirety.
The disclosure relates to an ion beam irradiation apparatus for irradiating a to-be-irradiated object with an ion beam, and a method for use in the ion beam irradiation apparatus.
An ion beam irradiation apparatus generates an ion beam from an ion source, where the ion beam is used for making various semiconductor products. Periodically maintenance of the ion beam irradiation apparatus, and specifically, the ion source, is required.
It is an aspect to provide an ion beam irradiation apparatus and method that allows for quickly starting maintenance of an ion source after an operation of the ion source is stopped.
According to an aspect of one or more embodiments, there is provided an ion beam irradiation apparatus comprising a plasma generation container in which plasma is generated; a vaporizer connected to the plasma generation container; a halogen gas supply passage through which a halogen gas is supplied to the vaporizer; an air supply passage through which air is supplied to the vaporizer; and an evacuation passage through which a reaction product produced through a reaction between the halogen gas and the air is evacuated to an outside of the ion beam irradiation apparatus.
According to another aspect of one or more embodiments, there is provided a method for an ion beam irradiation apparatus comprising a plasma generation container in which plasma is generated, a vaporizer connected to the plasma generation container, a halogen gas supply passage through which a halogen gas is supplied into the vaporizer, an air supply passage through which air is supplied to inside of the vaporizer, and an evacuation passage through which a reaction product produced through a reaction between the halogen gas and the air is evacuated to an outside of the ion beam irradiation apparatus, the method comprising after stopping an ion beam producing operation of the ion beam irradiation apparatus: performing one or more times both an air supply step of supplying the air via the air supply passage and an evacuation step of evacuating the reaction product via the evacuation passage; and performing the air supply step again to bring an inside of the ion beam irradiation apparatus to an atmospheric pressure.
According to yet another aspect of one or more embodiments, there is provided a method comprising stopping the supply of a halogen gas to a vaporizer in vacuum chamber of an ion beam irradiation apparatus; performing an air supply step in which air is supplied to the vacuum chamber; performing an evacuation step in which a reaction product between the air and residual halogen gas is evacuated from the vacuum chamber; and performing the air supply step again in which air is supplied to the vacuum chamber to bring the vacuum chamber from a vacuum to an atmospheric pressure.
The above and/or other aspects will become apparent and more readily appreciated from the following description of various embodiments, taken in conjunction with the accompanying drawings, in which:
In maintenance of an ion source used in an ion beam irradiation apparatus, the inside of the ion beam irradiation apparatus in a vacuum atmosphere is changed to an atmospheric atmosphere, whereafter the ion source is demounted from the ion beam irradiation apparatus, and replacement of consumables constituting the ion source are performed.
In the related art, when changing the inside of the ion beam irradiation apparatus from a vacuum atmosphere to atmospheric atmosphere, the inside of the apparatus is filled with a noble gas represented by nitrogen, thereby bringing a pressure inside the apparatus to atmospheric pressure.
There are various types of ion beams, and an ion beam may contain metal ions. In this case, an ion beam containing metal ions can be extracted from plasma generated from vapor of a metal material vaporized using a vaporizer.
With recent progress in research on vaporizers, a vaporizer may be configured such that a metal material such as aluminum or tungsten is placed in a crucible of the vaporizer, and a halogen gas such as chlorine or fluorine is introduced into the crucible to produce a reaction product through a chemical reaction between the metal material and the halogen gas, whereafter the reaction product is heated, and the resulting vapor of the reaction product is supplied to a plasma generation container.
An ion source equipped with the above vaporizer requires that the concentration of a toxic halogen gas remaining in the ion source should be reduced to a sufficiently low level before maintenance. Air is typically not used to purge the toxic halogen gas because air has several disadvantages, for example, causing deterioration of the performance of the ion source by causing oxidation, condensation, and unexpected reactions. Therefore, an inert gas such as dry nitrogen may be used to avoid these disadvantages. In a case where nitrogen gas is supplied to bring the pressure of an ion source to atmospheric pressure, as with the related art, the inside of the ion source is bought to atmospheric pressure by: alternately repeating a step of filling the inside of the ion source with nitrogen gas and a step of evacuating the inside of the ion source, until the concentration of a halogen gas remaining in the ion source is reduced to a sufficiently low level; and then supplying nitrogen gas into the ion source again. In this technique, there are several disadvantages in that it takes a long time until the halogen gas concentration reaches the sufficiently low level, and thus it takes a long time to bring the inside of the ion source to atmospheric pressure and start maintenance.
Therefore, it is an aspect to provide an ion beam irradiation apparatus and gas evacuation method capable of making it possible to more quickly start maintenance of an ion source.
According to some embodiments, there is provided an ion beam irradiation apparatus which comprises: a plasma generation container for generating plasma thereinside; a vaporizer connected to the plasma generation container; a halogen gas supply passage for supplying a halogen gas to the vaporizer; an air supply passage for supplying air to the vaporizer; and an evacuation passage for evacuating a reaction product produced through a reaction between the halogen gas and the air, to outside of the apparatus.
In some embodiments, air is supplied, instead of supplying nitrogen gas as in the related art. Thus, a water component in the supplied air reacts with the halogen gas remaining in the vaporizer, thereby making it possible to quickly reduce the concentration of the halogen gas to a low level, and thus making it possible to quickly start maintenance of the ion source.
In order to reliably prevent oxidation of components, in some embodiments, the ion beam irradiation apparatus may comprise a measuring device for measuring a temperature of the plasma generation container.
In order to make it possible to more quickly start the maintenance of the ion source, in some embodiments, the ion beam irradiation apparatus may comprise a nitrogen supply passage for supplying nitrogen to the plasma generation container.
In order to make it possible to more quickly start the maintenance of the ion source, in some embodiments, the ion beam irradiation apparatus may comprise a cooling passage for cooling the plasma generation container.
According to some embodiments, there is provided a gas evacuation method for use in an ion beam irradiation apparatus comprising: a plasma generation container for generating plasma thereinside; a vaporizer connected to the plasma generation container; a halogen gas supply passage for supplying a halogen gas into the vaporizer; an air supply passage for supplying air to inside of the vaporizer; and an evacuation passage for evacuating a reaction product produced through a reaction between the halogen gas and the air, to outside of the apparatus, the gas evacuation method comprising, before maintenance of the ion beam irradiation apparatus: performing an air supply step of supplying the air via the air supply passage and an evacuation step of evacuating the reaction product via the evacuation passage, one or more times; and then lastly performing the air supply step again to bring inside of the apparatus to atmospheric pressure.
In various embodiments, air is supplied, instead of supplying nitrogen gas as in the related art. Thus, a water component in the supplied air reacts with the halogen gas remaining in the vaporizer, thereby making it possible to early reduce the concentration of the halogen gas to a low level, and thus making it possible to more quickly start maintenance of the ion source.
According to various embodiments, the ion source IS may comprise a plasma generation container 2 for generating plasma P thereinside, a vaporizer S having one end connected to the plasma generation container 2, a halogen gas supply passage 13 for supplying a halogen gas to the vaporizer S from the side of the other end of the vaporizer S, and an extraction electrode E for extracting an ion beam IB from the plasma P inside the plasma generation container 2.
In some embodiments, various other components, such as a cathode for generating the plasma P inside the plasma generation container 2, a filament for heating the cathode, a reflective electrode disposed inside the plasma generation container 2 and opposed to the cathode to reflect electrons released from the cathode, toward the cathode, and an electromagnet generating a magnetic field along a direction along which the cathode and the reflective electrode are opposed to each other, inside the plasma generation container 2, may be arranged around the plasma generation container 2. However, illustration of these components is omitted for ease of explanation and conciseness.
A block comprising the plasma generation container 2 and the vaporizer S of the ion source IS is formed as an ion source head and supported by an ion source flange 1 through a non-illustrated structural member. Further, the ion source flange 1 is fixed to a vacuum container C by a non-illustrated fastener such as bolts. The ion source flange 1 is provided with a cooling passage R for cooling the ion source head. The cooling passage R is a circulation passage for a refrigerant or air.
The extraction electrode E may include a suppression electrode 7 for preventing flow of electrons into the plasma generation container 2, and a ground electrode 8 for clamping a ground potential. A non-illustrated DC power supply is connected between the plasma generation container 2 and the suppression electrode 7, while the positive terminal of the DC power supply is connected to the plasma generation container 2. Thus, based on a potential difference between the plasma generation container 2 and the suppression electrode 7, an ion beam IB having a positive electrical charge is extracted from the plasma P through an ion extraction port 6 of the plasma generation container 2.
A first on-off valve 21 is provided on one side of the extraction electrode E oriented in a Z-direction which is an ion beam extraction direction along which the ion beam IB is extracted. The first on-off value 21 is an openable-closable valve element configured to selectively divide a space of the vacuum container C into two spaces located forwardly and backwardly with respect to the first on-off value 21 in the Z-direction, wherein the first on-off value 21 is opened (in an open state) during the operation of the ion source IS.
The vaporizer S is connected to the plasma generation container 2. In some embodiments, the vaporizer S may include a crucible 3 in which a metal material 4 is placed, for example, in the form of a pellet, a powder or a lump, a heater 5 for raising the temperature of the crucible 3, a shield 9 shielding heat release from the heater 5, and a temperature measuring device TC (e.g., a thermocouple) for measuring the temperature of the crucible 3. The vaporizer S further comprises a halogen gas supply passage 13 for supplying a halogen gas such as chlorine or fluorine to the crucible 3.
A halogen gas bottle 15 is attached to the halogen gas supply passage 13 through a second on-off valve 14. During the operation of the ion source IS, the second on-off valve 14 is in an open state. Thus, the halogen gas is supplied from the halogen gas bottle 15 to the crucible 3, and chemically reacts with the metal material 4. When the crucible 3 is heated by the heater 5 to a high temperature, a reaction product produced through a reaction between the halogen gas and the metal material 4 is vaporized, and the resulting vapor V is supplied from the crucible 3 to the plasma generation container 2. The vapor V becomes plasma P in the plasma generation container 2, and the plasma P is extracted as an ion beam IB.
An air supply passage 16 is connected to the ion source flange 1. Air is fed from an air supply source 18 to the air supply passage 16 through a third on-off valve 17. In some embodiments, the air supply source 18 may be an air-filled bottle. In some embodiments, the air supply source 18 may be an air supply line equipped in a factory in which the ion beam irradiation apparatus IM is installed. During the operation of the ion source IS (i.e., during extraction of the ion beam IB from the plasma P inside the plasma generation container 2), the third on-off valve 17 is closed (in a closed state).
The vaporizer S may be prepared to have a flange for mounting the vaporizer S to the ion source flange 1 therethrough, and configured such that the crucible 3 is supported by the flange, and the halogen gas supply passage 13 is connected to the flange.
In order to allow the inside of the vacuum container C to be maintained at a certain degree of vacuum during the operation of the ion source IS, the inside of the vacuum container C is evacuated. Returning to
In some embodiments, the evacuation passage 11 may be connected to a non-illustrated vacuum pump. In some embodiments, the evacuation passage 11 may be connected to an evacuation line equipped in a factory in which the ion beam irradiation apparatus IM is installed.
Before performing maintenance of the ion source IS, the operation of the ion source IS is stopped, and air is supplied into the apparatus.
Before starting the supply of air to the vacuum container C, each of the first on-off valve 21, the second on-off valve 14 and the fourth on-off valve 12 is changed to a closed state, and only the third on-off valve 17 is changed to an open state.
Then, air is supplied from the air supply source 18 through the air supply line 16 to respective parts of the ion source IS according to the flow indicated by the arrows in
When the operation of the ion source IS is stopped, the halogen gas supplied to the vaporizer S, the plasma generation container 2, etc., remains inside the apparatus. Thus, when supplying air to the respective parts, the residual halogen gas and a water component of the air react with each other to produce a reaction product (gas).
After the elapse of a given time after the air supply is started, or after the pressure of the vacuum container C reaches a given value after the air supply is started, gas inside the vacuum container C is evacuated to the outside of the apparatus. A state at the time of evacuation is depicted in
While not illustrated in the figures, in some embodiments, a controller or hardware control logic may be communicatively connected to each of the first on-off valve 21, the second on-off valve 14, the third on-off valve 17, and the fourth on-off valve 12, and the controller may be coded to or the hardware control logic may be configured to control respective open and closed states of each of the first on-off valve 21, the second on-off valve 14, the third on-off valve 17, and the fourth on-off valve 12 as described with respect to
When nitrogen gas is supplied to bring the pressure of the ion source IS to atmospheric pressure as in related art, it takes a long time until the halogen gas concentration reaches a low level. In contrast, in various embodiments, when air is supplied instead of nitrogen, a water component in the supplied air reacts with the residual halogen gas, so that it becomes possible to more quickly reduce the concentration of the halogen gas in the apparatus to a low level.
Then, after the halogen gas concentration reaches the given concentration or less, air is lastly supplied again, as described in connection with
In some embodiments, in a situation where the amount of residual halogen gas is relatively large, and therefore the halogen gas concentration cannot be sufficiently reduced within one duration of air supply, the step of performing air supply (air supply step) described in connection with
When performing the air supply, there may be a concern that oxygen contained in air oxidizes components constituting the ion source IS. During the operation of the ion source 1S, the plasma generation container 2 has a relatively high temperature, as compared to other components constituting the ion source IS. Metal components (made of a high-melting-point metal, such as tungsten or molybdenum), such as the cathode and the reflective electrode, mounted around the plasma generation container 2, have an accelerated reaction with oxygen under high temperatures. If the metal components are oxidized, the oxidized metal components will hinder the operation of the ion source IS. Thus, it is advantageous to start the air supply after the elapse of a given time once the operation of the ion source IS has stopped. The term “given time” here means a period of time derived by an experimental rule. In some embodiments, the “given time” may be a period of time for the temperature of the plasma generation container 2 to decrease to a given temperature or less.
Instead of waiting for the elapse of the given time, in some embodiments, the temperature of the plasma generation container 2 may be actually measured, and the air supply may be started according to the actually measured value (i.e., once the measured value has dropped below a threshold value, where the threshold value may be set experimentally).
With regard to the temperature measurement of the plasma generation container 2, in some embodiments, a thermocouple may be mounted to the plasma generation container 2 to directly measure the temperature of the plasma generation container 2. IN some embodiments, the temperature measurement may be performed using a radiation thermometer or a thermography, instead of the thermocouple.
In some embodiments, the temperature of the vaporizer S connected to the plasma generation container 2 may be measured by a thermocouple TC, and the temperature of the plasma generation container 2 may be indirectly derived in consideration of a temperature correlation between the vaporizer S and the plasma generation container 2. The temperature correlation may be set experimentally.
In some embodiments, the temperature of the plasma generation container 2 may be reduced by means of natural cooling. However, in view of shortening of cooling time, it is advantageous to perform the cooling using a refrigerant. For example, as depicted in
In some embodiments, a configuration as shown in
One end of a nitrogen supply passage 23 is connected to the ion source flange 1, and the other end of the nitrogen supply passage 23 is connected to a nitrogen supply bottle 24 through a fifth on-off valve 22. Prior to the supply of air to the vacuum container C, the cooling of the plasma generation container 2 is performed by introducing nitrogen via the nitrogen supply passage 23.
That is, a step of supplying nitrogen to cool the plasma generation container 2 (nitrogen supply step) is performed before the start of the air supply step as described with respect to the embodiments of
In some embodiments, prior to starting the air supply after the nitrogen supply, nitrogen inside the apparatus is evacuated to the outside of the ion beam irradiation apparatus IM via the evacuation passage 11. In some embodiments, the supply and evacuation of nitrogen may be performed a plurality of times to sufficiently reduce the temperature of the plasma generation container 2.
In the embodiment illustrated in
In a situation in which the temperature of the vaporizer S is relatively high at the start of maintenance of the ion source IS, and it takes a long time before the vaporizer S can be demounted, air from the air supply passage 16 and/or nitrogen from the nitrogen supply passage 23 may cool the vaporizer S. In some embodiments, air from the air supply passage 16 or nitrogen from the nitrogen supply passage 23 may cool the vaporizer S.
Thus, in some embodiments, in addition to the air supply passage 16 and the nitrogen supply passage 23 illustrated in
With reference to
In conjunction with stopping the operation of the ion source IS, each of the first on-off valve 21, the second on-off valve 14 and the fourth on-off valve 12 is changed to the closed state.
Subsequently, in step S2, the method may wait for a given time. For example, in some embodiments, the method may wait until an elapsed time from the stopping of the ion source IS has occurred. As another example, an elapsed time since the operation of the ion source IS was stopped is counted, and the next step not performed until a given time (e.g., several ten minutes) has elapsed. For another example, the temperature of the plasma generation container 2 may be measured, and the method may wait until the temperature of the plasma generation container 2 is reduced to a given temperature or less.
Then, after the given time has elapsed, in step S3, air is supplied. For example, air is supplied to the vacuum chamber C as described above. More specifically, the third on-off valve 17 may be changed to the open state to perform the air supply.
Thereafter, in step S4, evacuation is performed. For example, after the elapse of a given time after the air supply was started, or after the pressure of the inside of the apparatus reaches a given pressure after the air supply was started, the inside of the apparatus may be evacuated.
According to the evacuation, gas which is a reaction product produced through a reaction between water in air and the halogen gas remaining in the ion beam irradiation apparatus is evacuated to the outside of the ion beam irradiation apparatus.
In step S6, air is supplied. For example, air is supplied again after the evacuation is performed in order to bring the inside of the ion beam irradiation apparatus IM (and thus the ion source IS) to an atmospheric pressure. Once the ion beam irradiation apparatus IM is at the atmospheric pressure, maintenance of the ion source IS may be performed.
After it is determined in the step S5 that the air supply in the step S3 and the evacuation in the step S4 are performed the given number of times (i.e., step S5, Y), the air supply for bringing the inside of the ion beam irradiation apparatus to atmospheric pressure is lastly performed in step S6. When it is determined in the step S5 that the air supply in the step S3 and the evacuation in the step S4 have not been performed the given number of times (i.e., step S5, N), the method may return to step S3.
The use of the above gas evacuation method makes it possible to more quickly reduce the concentration of the residual halogen gas to a low level, and thus makes it possible to may quickly start maintenance of the ion source IS.
In the example in
In the examples in
In order to effectively reduce the temperature of the plasma generation container 2, it is possible to employ a configuration in which a noble gas is supplied after stop of the operation of the ion source IS. Specifically, as shown in
In some embodiments, as illustrated in
Although the step of air supply S3 and the subsequent steps S4-S6 in the examples in
The embodiments illustrated in
It is to be understood that various embodiments have been described herein, but various changes and modifications may be made therein without departing from the spirit and scope thereof as set forth in appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-114899 | Jul 2022 | JP | national |
