JP2009211955A - Charged particle irradiation device, frequency adjustment device using it, and charged particle control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charged particle irradiation device suppressing leakage of a beam from a turned-off grid, and having a neutralizer having an excellent neutralization effect; a frequency adjustment device using it; and a charged particle control method. <P>SOLUTION: An ion gun 11 introduces Ar gas into a body 111 from a gas introduction part 114, and generates D.C. hot-cathode discharge between a filament 113 and an anode 112 to generate plasma of Ar. Then, a voltage gradient is provided to split acceleration grids 116a and 116b having two split structures in a direction for emitting ions to emit ions. A positive voltage is applied to the split acceleration grid on the side for turning off an ion beam, and a negative voltage is applied to a deceleration grid 117. Thereby, leakage of the ion beam from the grid on the stopping side is suppressed, and the neutralization effect of the neutralizer can be improved. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a charged particle irradiation apparatus that irradiates charged particles such as ions, a frequency adjustment apparatus using the same, and a charged particle control method, and more particularly to a charged particle irradiation apparatus capable of independently controlling a plurality of charged particle beams, The present invention relates to a frequency adjusting device and a charged particle control method using the same.

  The resonance frequency of a crystal resonator, which is a typical piezoelectric element, is determined by the thickness of the crystal piece and the thickness of the metal electrode formed on the surface thereof. Conventionally, in order to obtain a desired resonance frequency of a crystal resonator, i) a crystal piece is cut out with a specified thickness, ii) the surface is polished, and a metal film electrode serving as a base is formed on the surface by sputtering deposition or the like. Iii) A process of adjusting the thickness of the metal electrode film while measuring the resonance frequency is performed. As a method for adjusting the thickness of the metal electrode film, a method is known in which an ion beam is irradiated from an ion gun and the metal electrode film is etched and thinned.

  In recent years, with the aim of saving the space of the apparatus and shortening the processing time, for example, as shown in Patent Document 1, by irradiating a plurality of piezoelectric elements with a plurality of ion beams from a single ion gun, a plurality of quartz crystals at a time. Processing the vibrator is performed.

  The charged particle irradiation apparatus used for the frequency adjusting apparatus introduces Ar gas, for example, as a discharge gas into the main body from the gas introduction unit, energizes and heats the filament, and Ar by direct current hot cathode discharge between the filament and the anode. Plasma is generated, and a high voltage is applied to the acceleration grid by a high-voltage power source to generate a potential gradient in the direction of accelerating ions, and Ar positive ions are extracted as an ion beam and placed on a mounting table. Irradiate the crystal unit.

In the charged particle irradiation apparatus disclosed in Patent Document 1, in order to generate a plurality of ion beams, a shielding grid in which a plurality of beam hole groups are formed, a divided acceleration grid, and a deceleration grid are arranged. Moreover, in this charged particle irradiation apparatus, the on / off control of the ion beam can be controlled by connecting the deceleration grid to the ground, making the on-side divided acceleration grid negative, and setting the off-side divided acceleration grid floating. Is going.
JP 2007-250523 A

  By the way, in the conventional charged particle irradiation apparatus, the neutralizer for preventing the charge of the to-be-processed object is provided. By supplying electrons with this neutralizer, it is possible to neutralize the ion beam.

  However, as described above, when one split acceleration grid is turned off to be in a floating state, depending on the emission current value of the neutralizer, electrons supplied from the neutralizer neutralize the charge of the split acceleration grid, and the ion beam In some cases, leakage occurred. In addition, when electrons supplied by the neutralizer flow to the split acceleration grid, there is a problem that the neutralizing effect of the ion beam is reduced.

  The same problem occurs not only when the metal electrode of the crystal resonator is polished by an ion beam but also when a processing object is processed using a plurality of charged particle beams.

The present invention has been made in view of the above circumstances, and a charged particle irradiation apparatus capable of suppressing leakage from an off grid when independently controlling a plurality of charged particle beams, and An object of the present invention is to provide a frequency adjusting device and a charged particle control method using the above-mentioned.
Another object of the present invention is to provide a charged particle irradiation apparatus having a neutralizing effect with a good neutralizer, a frequency adjusting apparatus using the same, and a charged particle control method.

In order to achieve the above object, a charged particle irradiation apparatus according to the first aspect of the present invention includes:
A charged particle irradiation apparatus for irradiating charged particles,
Charged particle generating means for generating charged particles;
An acceleration grid having a plurality of divided grids for extracting the charged particles generated by the charged particle generating means and outputting a charged particle beam;
Control means for individually controlling the potential of the acceleration grid divided into a plurality of parts,
When the charged particle beam is blocked, the divided grid that blocks the charged particle beam is set to a first potential higher than a potential of a vacuum chamber in which the charged particle irradiation device is disposed.

A shielding grid is provided between the charged particle generating means and the acceleration grid,
The first potential may be the same as or higher than the potential of the shielding grid.

  A first power supply for applying the first potential may be provided.

A deceleration grid is provided on the charged particle beam output side of the acceleration grid,
The deceleration grid may be a second potential lower than the potential of the vacuum chamber.

A deceleration grid is provided on the charged particle beam output side of the acceleration grid,
You may provide the reflector installed in the outer side of the said deceleration grid.

  The reflector may have a second potential lower than the potential of the vacuum chamber.

A neutralizer for neutralizing the charge of the charged particle beam;
The second potential may be the same as or lower than the negative side of the neutralizer.

  A second power source for applying the second potential may be provided.

  You may further provide the neutralizer which neutralizes the electric charge of the said charged particle beam.

  The control means may include a switch circuit individually installed between each of the divided grids and the first power supply, and a means for individually turning on and off the switch circuit.

In order to achieve the above object, a frequency adjustment apparatus according to a second aspect of the present invention is provided.
An ion gun comprising the charged particle irradiation apparatus according to the first aspect;
An arrangement means for arranging a plurality of piezoelectric devices;
Resonance frequency discrimination means for discriminating resonance frequencies of a plurality of piezoelectric devices arranged by the arrangement means;
With
While the resonance frequency discriminating means monitors the resonance frequency of the plurality of piezoelectric devices arranged by the arrangement means, the plurality of piezoelectric devices are irradiated with an ion beam in parallel to at least part of each piezoelectric device. The resonance frequency of the plurality of piezoelectric devices is adjusted by etching.

In order to achieve the above object, a charged particle control method according to a third aspect of the present invention includes:
Generate charged particles by a charged particle generating means in a predetermined container arranged inside the vacuum chamber,
An acceleration grid having a plurality of divided grids for extracting the charged particles generated by the charged particle generating means and outputting a charged particle beam is disposed,
A voltage gradient is formed in a direction in which charged particles are extracted by applying a voltage to each accelerating grid, and charged particles in the plasma are ejected as a charged particle beam,
Individually controlling the potential of the acceleration grid divided into a plurality of parts,
The charged particle beam emission is shielded by setting the acceleration grid to a first potential higher than the potential of the vacuum chamber.

A shielding grid is provided between the charged particle generating means and the acceleration grid,
The first potential may be the same as or higher than the potential of the shielding grid.

A deceleration grid is arranged outside the acceleration grid,
The deceleration grid may be a second potential lower than the potential of the vacuum chamber.

  According to the present invention, by controlling the potential of each of the divided acceleration grids, the leakage from the grid that has stopped the irradiation is suppressed, and the neutralizer has a good neutralization effect, A frequency adjusting device and a charged particle control method using the same can be provided.

  Hereinafter, a case where the charged particle irradiation apparatus according to each embodiment of the present invention is applied to a frequency adjustment apparatus that adjusts a resonance frequency by etching a metal electrode of a crystal resonator will be described as an example.

(First embodiment)
A configuration example of the frequency adjustment device according to the present embodiment is shown in FIG. FIG. 2 is an exploded perspective view of the frequency adjusting device shown in FIG. The frequency adjustment device includes an ion gun 11, a mounting unit 12 on which a crystal resonator to be processed is mounted, a resonance frequency measuring unit 13 that detects a resonance frequency of the crystal resonator, a control unit 14, a shutter 15, Consists of

  The ion gun 11 is a device that generates two ion beams Ia and Ib, and includes a main body (chamber) 111, an anode (electrode) 112, a filament 113, a gas introduction unit 114, a shielding grid 115, and an acceleration grid. 116 (split acceleration grids 116a and 116b), deceleration grid 117, neutralizer 125, filament power supply 131, discharge power supply 132, beam power supply 133, acceleration power supply 134, acceleration grid control switches 141a and 141b, An acceleration grid off switch 142, an acceleration grid on switch 143, a deceleration grid control switch 144, and a beam power switch 145 are provided.

The placement unit 12 shown in FIG. 1 arranges two crystal resonators 201a and 201b to be processed with a predetermined distance therebetween.
The resonance frequency measuring unit 13 is connected to the crystal resonators 201a and 201b mounted on the mounting unit 12, and measures the resonance frequency.

  The control unit 14 includes a microprocessor, a sequencer, or the like, and controls the operation of each unit. In particular, in the present embodiment, the acceleration grid control switches 141a and 141b are controlled according to the detection result from the resonance frequency measurement unit 13. In addition, the shutter 15 is controlled to open and close. It is also possible to adopt a configuration in which the control unit 14 is incorporated in the resonance frequency measurement unit 13.

  The shutter 15 includes a shutter 15a disposed in front of the crystal resonator 201a and a shutter 15b disposed in front of the crystal resonator 201b, and shields the ion beams Ia and Ib, respectively.

  1 and FIG. 2 are arranged in a vacuum chamber.

The main body 111 is composed of a cylindrical metal casing whose surface is coated and defines a processing space. The main body 111 is maintained at the same potential as the negative electrode of the filament power supply 131.
The anode 112 is disposed in the shape of a cylindrical band in the vicinity of the side wall of the main body 111 and functions as an anode for DC discharge.
The filament 113 constitutes a hot cathode for DC discharge.
The gas introduction unit 114 introduces a discharge gas such as Ar into the main body 111.

The filament power supply 131 is composed of a DC power supply, and energizes the filament 113 to heat it.
The discharge power supply 132 applies a DC voltage for discharge between the anode 112, the main body 111 and the filament power supply 131.

  The beam power supply 133 increases the voltage of the plasma in the main body 111 during ion beam irradiation. Further, an acceleration grid-off switch 142 is connected to the positive electrode side of the beam power supply 133, and further, acceleration grid control switches 141a and 141b are connected. By turning on the acceleration grid off switch 142 and further connecting the acceleration grid control switch 141a or / and 141b of the grid for turning off the ion beam to the acceleration grid off switch 142, the divided acceleration grid 116a or / and 116b is connected. Apply a positive voltage to

  The acceleration power supply 134 applies a negative voltage to the divided acceleration grids 116 a and 116 b and the deceleration grid 117. The negative side of the acceleration power supply 134 is connected to acceleration grid control switches 141a and 141b. By appropriately connecting the acceleration grid control switches 141a and 141b, the divided acceleration grids 116a and 116a on the side where the ion beam is turned on are connected. A negative voltage can be applied to 116b. The negative side of the acceleration power supply 134 is connected to the deceleration grid control switch 144, and a negative voltage of the acceleration power supply is applied to the deceleration grid 117 by this switch.

  The neutralizer 125 supplies electrons to the ion beams Ia and Ib to neutralize the charge of the ions and prevent the charge of the piezoelectric device from being charged.

  The shielding grid 115 is disposed on the ion emission surface of the main body 111 and encloses ions in the chamber except for a beam hole (beam extraction hole) portion. The ion gun 11 outputs two beams, and the grid pattern has a configuration for two beams as shown in FIG. This grid pattern has a configuration in which two beam hole groups 61 are formed at a distance d2. Further, the shielding grid 115 has the same potential as the main body 111.

  The acceleration grid 116 is disposed substantially parallel to the ion emission surface of the main body 111 at a predetermined distance from the shielding grid 115. As shown in FIG. 3B, the acceleration grid 116 has a shape in which a disk is divided into two. In other words, the acceleration grid 116 has a structure in which two semi-disc-shaped divided acceleration grids 116a and 116b are combined. As shown in FIG. 3B, beam holes 612 are formed in the acceleration grid 116 at positions that overlap the beam holes 611 formed in the shielding grid 115. The area of the beam hole 612 of the acceleration grid 116 is smaller than the area of the beam hole 611 of the shielding grid 115, for example, 0.2 to 0.8 times. In addition, a beam hole group for one beam output is arranged in one divided acceleration grid 116a, 116b. In the present embodiment, the area of the beam hole formed in the acceleration grid is smaller than that of the beam hole formed in the shielding grid. However, the size of the beam hole is not limited to this and may be the same area. . Alternatively, at least one of the beam holes of the acceleration grid may be smaller than the beam hole of the corresponding shielding grid.

  When the ion beam Ia is turned off, the split acceleration grid 116a is connected to the positive side of the beam power supply 133 by the acceleration grid off switch 142 and the acceleration grid control switch 141a, and the positive voltage of the beam power supply 133 is applied. Is done. When the ion beam Ia is turned on, the divided acceleration grid 116a is connected to the negative side of the acceleration power supply 134 by the acceleration grid on switch 143 and the acceleration grid control switch 141a, and the negative voltage of the acceleration power supply 134 is set. Is applied.

  Similarly, when the ion beam Ib is turned off, the divided acceleration grid 116b is connected to the positive side of the beam power supply 133 by the acceleration grid off switch 142 and the acceleration grid control switch 141b. A voltage is applied. When the ion beam Ib is turned on, the divided acceleration grid 116b is connected to the negative side of the acceleration power supply 134 by the acceleration grid on switch 143 and the acceleration grid control switch 141b, and the negative voltage of the acceleration power supply 134 is set. Is applied.

  In the present embodiment, in particular, the split acceleration grids 116a and 116b for turning off the ion beam are set to a positive potential, thereby suppressing ion beam leakage better than when the floating state is set. it can. Further, as will be described later, in this embodiment, since the deceleration grid 117 is set to a negative potential, it is possible to suppress the electrons supplied from the neutralizer from being attracted to the off-side divided acceleration grid. Sometimes a good shielding effect can be obtained. Each of the acceleration grid control switches 141 a and 141 b is switched by a control signal from the control unit 14.

  The decelerating grid 117 is disposed on the ion emission surface of the main body 111 close to and away from the accelerating grid 116 and substantially in parallel. The deceleration grid 117 has the same configuration as the shielding grid 115, as shown in FIG. In the present embodiment, the area of the beam hole 613 of the deceleration grid 117 is formed to be approximately the same as the area of the beam hole 611 of the shielding grid 115. In this embodiment, the deceleration grid 117 is applied with the negative voltage of the acceleration power supply 134 by turning on the deceleration grid control switch 144. By applying a negative voltage to the deceleration grid 117 in this way, it is possible to prevent electrons emitted from the neutralizer 125 from collecting near the deceleration grid 117, and further, from adhering to the acceleration grid 116. . Such an effect can be obtained by setting the potential of the deceleration grid 117 to a potential lower than the potential of the vacuum chamber. In general, a neutralizer is applied with a voltage lower than that of a vacuum chamber in which the neutralizer is disposed, and electrons are emitted using a potential difference from the vacuum chamber. In the present invention, the split acceleration grid for stopping the ion beam has a positive potential, so that electrons supplied from the neutralizer are easily drawn. When the split accelerating grid attracts electrons, the effect of neutralizing the ion beam by the neutralizer is diminished, and the irradiated object is charged. As will be described later with reference to FIG. 10, there is a problem that the rate is lowered when the irradiated object is charged. In order to avoid this, it is only necessary to give the electrons directivity not in the grid direction but in the irradiation object direction. In the present invention, the amount of electrons traveling in the direction of an object to be irradiated is applied to an electrode (deceleration grid 117) disposed between the neutralizer and the acceleration grid by applying a voltage at least lower than the peripheral potential (vacuum chamber). Increases the neutralization effect. If the decelerating grid 117 is set to the same potential as the negative electrode side of the neutralizer 125 or a potential lower than that, a further excellent effect can be obtained.

  In the present embodiment, the shielding grid 115, the acceleration grid 116, and the deceleration grid 117 are arranged substantially in parallel, as shown in FIG. 4, and are separated from each other by substantially the same distance.

Next, the operation of the frequency adjustment apparatus having the above configuration will be described.
First, the crystal resonators 201a and 201b to be processed are placed on the placement unit 12, and the inside of the vacuum chamber is decompressed.

  For example, Ar gas is introduced into the main body 111 as a discharge gas from the gas introduction unit 114, the filament 113 is energized and heated by the filament power supply 131, and a DC voltage is applied between the filament 113 and the anode 112. As a result, a direct current hot cathode discharge is performed to generate Ar plasma.

  Subsequently, the beam power switch 145 is turned on, the acceleration grid on switch 143 is further turned on, the divided acceleration grid control switches 141a and 141b are connected to the acceleration grid on switch 143 side, and have the same potential as the negative voltage of the acceleration power supply. And Thus, a high voltage is applied between the anode 112 and the acceleration grid 116 by the discharge power source 132. As a result, a potential gradient is generated in the direction of accelerating the ions generated by the plasma in the main body 111, and Ar positive ions are extracted as ion beams Ia and Ib from the extraction beam hole. At this time, the deceleration grid control switch 144 is turned on, and the deceleration grid 117 is also at the same potential as the negative voltage of the acceleration power supply.

  A metal electrode formed on the first crystal resonator 201a mounted on the mounting portion 12 and a metal formed on the second crystal resonator 201b by the two irradiated ion beams Ia and Ib. The electrodes are etched and the respective resonance frequencies are adjusted.

  During this time, the resonance frequency measurement circuit 13 measures the resonance frequency of each of the first crystal resonator and the second crystal resonator, and outputs the measurement result to the control unit 14.

  The control part 14 repeats the process shown in FIG. In FIG. 5, in order to facilitate understanding, the control related to the first crystal resonator 201a and the control related to the second crystal resonator 201b are sequentially performed. However, both controls are performed in parallel. Is desirable.

  First, it is determined whether or not the frequency adjustment relating to the first crystal resonator 201a has been completed (step S11). Initially, after the acceleration grid off switch 142 is turned on, the divided acceleration grid control switch 141a is connected to the acceleration grid off switch 142 side, the ion beam Ia is stopped, and the shutter 15a is further closed. If the frequency adjustment is not completed (step S11; NO), the divided acceleration grid control switch 141a is connected to the acceleration grid on switch 143 side (step S12), the shutter 15a is opened (step S13), and the crystal resonator 201a frequency adjustment is started.

  It is determined whether or not the resonance frequency of the first crystal resonator 201a detected by the resonance frequency measurement unit 13 matches the target frequency (step S14).

  If it coincides with the target frequency (step S14; Yes), the acceleration grid off switch 142 is turned on, and the divided acceleration grid control switch 141a is connected to the acceleration grid off switch 142 (step S15). By connecting the acceleration grid control switch 141 a to the acceleration grid off switch 142 side, the divided acceleration grid 116 a can be set to the positive potential of the beam power supply 133 and can be set to the same potential as the shielding grid 115. As a result, the ion beam Ia irradiated from the divided acceleration grid 116a can be made very weak without substantially affecting the intensity of the ion beam Ib irradiated from the divided acceleration grid 116b.

  Furthermore, in this embodiment, the deceleration grid is set to the same potential as the negative voltage of the neutralizer. Thereby, it is possible to prevent electrons supplied from the neutralizer from being supplied to the divided acceleration grid, and it is possible not to reduce the neutralizing effect of the neutralizer.

  Further, the solenoid is driven, the shutter 15a is closed, and the irradiation of the ion beam Ia to the first crystal resonator 201a is completely blocked (step S16).

  On the other hand, if it is determined in step S14 that the resonance frequency of the first crystal resonator 201a detected by the resonance frequency measurement unit 13 does not match the target frequency (step S14; No), the processing is continued as it is. Continue processing. If it is determined in step S11 that the frequency adjustment processing of the first crystal resonator 201a has been completed (step S11; Yes), steps S12 to S16 are skipped.

  Next, the control unit 14 determines whether or not the frequency adjustment related to the second crystal resonator 201b has been completed (step S17). At this time, the acceleration grid off switch 142 is turned on, the divided acceleration grid control switch 141b is connected to the acceleration grid off switch side 142, and the shutter 15b is closed. If the frequency adjustment is not completed (step S17; NO), the divided acceleration grid control switch 141b is connected to the acceleration grid on-side switch 143 side (step S18), the shutter 15b is opened (step S19), and the crystal resonator 201b frequency adjustment is started. It is determined whether or not the resonance frequency of the second crystal resonator 201b detected by the resonance frequency measurement unit 13 matches the target frequency (step S20).

  If it coincides with the target frequency (step S20; Yes), the acceleration grid control switch 141b is connected to the acceleration grid off switch side 142 (step S21). As a result, the divided acceleration grid 116 b has the same potential as the positive voltage of the beam power supply 133 and the same potential as the shielding grid 115. In this way, the ion beam Ib irradiated from the divided acceleration grid 116b becomes very weak. Further, the solenoid is driven to close the shutter 15b, and the irradiation of the ion beam Ib to the second crystal resonator 201b is completely blocked (step S22).

  On the other hand, if it is determined in step S20 that the resonance frequency of the second crystal resonator 201b detected by the resonance frequency measurement unit 13 does not match the target frequency (step S20; No), the processing is continued as it is. Continue processing. If it is determined in step S17 that the frequency adjustment processing of the second crystal resonator 201b has been completed (step S17; Yes), steps S18 to S22 are skipped.

  Finally, it is determined whether or not the processing of the first crystal resonator 201a and the processing of the second crystal resonator 201b have been completed (step S23), and if completed (step S23; Yes), the processing is performed. The process is terminated, and the process proceeds to a process such as unloading. If the process is not completed (step S23; No), the process returns to step S11 to continue the metal electrode etching process.

  In this way, by appropriately switching the acceleration grid control switches 141a and 141b for the intensity of the ion beams Ia and Ib irradiated from the ion gun 11, the processing of each crystal resonator can be finished at an appropriate timing.

  In the present embodiment, as described above, a negative voltage is applied to the deceleration grid, and a positive voltage is further applied to the split acceleration grid that is turned off, so that the ion beam on the side that is turned on is not affected. It is possible to suppress leakage.

  FIG. 7 shows the result of measuring the relationship between the collector current and the collector voltage by the apparatus having the configuration shown in FIG. In the apparatus shown in FIG. 6, using the ion gun and neutralizer of the present embodiment, a collector electrode was installed via an insulator with respect to the mask, and the change in the collector current when a predetermined collector voltage was applied was measured. The collector electrode was installed at the position to be irradiated with the ion beam (the position where the crystal resonator 201 is arranged in FIG. 1). In addition, as shown in FIG. 7, when a negative bias voltage is applied to the deceleration grid and both beams are turned on, when only one side is turned on, the deceleration grid is connected to the ground and both beams are turned on. In this case, the collector current was measured when only one side was turned on. When only one side was turned on, a positive bias voltage was applied to the off-side divided acceleration grid.

  As is apparent from FIG. 7, when a bias voltage is applied to the deceleration grid, the collector current switches between positive and negative in the vicinity of the collector voltage of 0 V, both when the ion beam is turned on and when one side is turned off. That is, it can be seen that the charge is neutralized by charged particles irradiated to the ion collector and electrons supplied from the neutralizer. On the other hand, when the deceleration grid is connected to the ground, when both sides are turned on, it changes in substantially the same manner as when a bias voltage is applied to the deceleration grid. However, when only one side is turned on, a positive current flows regardless of whether the collector voltage is positive or negative, and it is clear that the charge is not neutralized by the charged particles and the electrons supplied from the neutralizer. Thus, according to the charged particle irradiation apparatus of the present invention, it can be said that a good neutralization effect can be obtained even when one ion beam is turned off.

Next, referring to FIG. 8, beam leakage is compared between when the off-side divided acceleration grid is set to a floating potential and when it is set to a positive potential. FIG. 8 shows a case where the ion gun and the neutralizer shown in FIG. 1 are used, and one split acceleration grid 116a is set to an acceleration potential, and the other split acceleration grid 116b is set to a floating potential (the switch 141b is connected to both). The frequency change of the crystal unit 201b when the main body potential is set (the state where the switch 141b is connected to the switch 142 side) and the acceleration potential is set (the state where the switch 141b is connected to the switch 143 side). It is the result of measuring ΔF. For the measurement, an AT-cut 25 MHz fundamental wave and a quartz vibrator with an excitation electrode Ag were used, the beam voltage was 1000 V, the discharge current was 500 mA, and the neutralizer emission current was 30 mA. When the divided acceleration grid 116b is set to a floating potential, it can be seen that the frequency change of the crystal resonator 201b is conspicuous and the ion beam leaks. Comparing this with the frequency change when the divided acceleration grid 116b is set to the acceleration potential (that is, when both beams are turned on), it can be seen that the frequency change ΔF is about 45% and leakage is large. On the other hand, when the divided acceleration grid 116b is set to the main body potential, there is almost no frequency change. Compared with the change in frequency when both beams are turned on, the change in frequency ΔF is about 5%, indicating that the ion beam is well cut off and ion beam leakage on the off side is suppressed.

Here, FIG. 9 shows the result of measuring the potential of the divided acceleration grid 116b by changing the neutralizer emission current value when the divided acceleration grid 116b is set to the floating potential in the measurement shown in FIG. From the figure, it can be seen that when the neutralizer emission current value rises above a certain value (around 20 mA in the figure), the potential of the off-side divided acceleration grid sharply drops to the potential of the vacuum chamber (ground potential). In other words, if the neutralizer current value is small, the ion beam can be blocked well by setting the floating potential. However, if the neutralizer current value is large, the potential of the off-side divided acceleration grid becomes the potential of the vacuum chamber. The beam leaks down and cannot be suppressed. In the measurement of FIG. 8, since the neutralizer current value was large and the potential of the off-side divided acceleration grid was the potential of the vacuum chamber, beam leakage occurred.

  There are various neutralizer current values, that is, the amount of electrons supplied for neutralizing the ion beam. For example, as the ion beam current density increases, the amount of electrons required for neutralization increases. The ion beam current density increases as the number of holes formed in the grid increases.

In addition, for example, in the case where a crystal resonator to be irradiated with an ion beam is connected to a measuring instrument as shown in FIG. 11A, and in the case where it is connected to a measuring instrument as shown in FIG. The amount of neutralizing electrons required in the case shown in FIG. This is because the surface to be irradiated enters a floating state and is charged due to the presence of the load capacity. Even in the case shown in FIG. 11A, if the resistance value is large, the charge flowing from the irradiation target surface to the ground is reduced, and the amount of neutralizing electrons is required as compared with the case where the resistance value is small. Alternatively, even if the irradiation target surface is connected to the ground, neutralizing electrons are required when the mask that defines the irradiation region is a dielectric or the like.

  From the above, the required neutralizer current value varies depending on the device configuration, etc., but if the off-side split acceleration grid is made higher than the vacuum chamber potential, the neutralizer current value needs to be increased. Even if it exists, beam leakage can be suppressed rather than making it a floating potential. More preferably, if the potential of the off-side divided acceleration grid is the same as or higher than the potential of the shielding grid, beam leakage can be suppressed regardless of the neutralizer current value. For example, in FIG. 9, the potential of the off-side divided acceleration grid drops around 20 mA, but this value varies depending on the shape of the ion gun, various set voltages, etc., so beam leakage does not depend on the current value of the neutralizer. It is effective to be able to suppress. By making the potential of the off-side split accelerating grid equal to or higher than the potential of the shielding grid, the potential gradient necessary for extraction of the ion beam, which is the original role of the accelerating grid, does not occur, and leakage is suppressed. To do.

FIG. 10A shows the result of measuring the frequency change ΔF using the ion gun and neutralizer of the present embodiment and applying a negative voltage to the deceleration grid and using the crystal resonator as a processing target. In the same figure, when two ion beams are turned on and when one of the ion beams is turned off, the on-side ion beam (Ia and Ib are turned off when Ia and Ib are turned on in the apparatus shown in FIG. 1). The frequency change ΔF of the crystal resonator corresponding to Ia in the case of For the measurement, an AT-cut 25 MHz fundamental wave and a quartz vibrator with an excitation electrode Ag were used, the beam voltage was 600 V, and the discharge current was 300 mA. When the split acceleration grid was turned off, a potential on the positive side of the beam power source was applied. When one of the ion beams was turned off after applying a negative voltage to the deceleration grid, the frequency change ΔF was within 5% compared to when two ion beams were turned on.
On the other hand, FIG. 10B shows the result of measuring the frequency change ΔF using the ion gun and neutralizer of the present embodiment and connecting the deceleration grid to the ground and using the crystal resonator as a processing target. The measurement conditions other than the potential of the deceleration grid are the same as in FIG. There was a difference of 20% in the frequency change ΔF between when both ion beams were turned on and when one of the ion beams was turned off. This result means that in the state where the deceleration grid is connected to the ground, the neutralizing effect of the ion beam is weakened and the crystal unit is charged. The electrons supplied from the neutralizer are attracted to the positive potential of the off-side divided acceleration grid, and the rate drops due to the shortage of electrons at the crystal resonator position and the crystal resonator being positively charged. Yes. On the other hand, in FIG. 10A, by applying a negative voltage to the deceleration grid arranged between the neutralizer and the off-side divided acceleration grid, the amount of electrons toward the crystal unit direction is increased, The crystal unit is prevented from being charged and the rate is maintained. Also from this point, it can be seen that the charged particle irradiation apparatus of the present embodiment has a low influence on the ion beam on the on side.

  Thus, in the charged particle irradiation apparatus of the present embodiment, the deceleration grid is set to the same potential as the negative voltage of the neutralizer, and the off-side divided acceleration grid is set to the same potential as the potential of the shielding grid. Since the leakage of the ion beam on the off side can be suppressed without impairing the strength of the current density, a good on / off characteristic of the ion beam can be obtained. Furthermore, the neutralizing effect of the ion beam by the neutralizer is not reduced.

  In addition, this invention is not limited to the said embodiment, A various change and application are possible. For example, in the above-described embodiment, the negative voltage is applied to the deceleration grid 117. However, the present invention is not limited to this, and a reflector 151 may be provided near the ion emission surface of the ion gun 51 as shown in FIGS. Is possible. In this case, the reflector 151 includes a hole 151a formed so as not to block the ion beams Ia and Ib as shown in FIG. Such a reflector 151 is installed, and a voltage equal to or lower than the negative voltage of the neutralizer is applied to the reflector 151 similarly to the deceleration grid 117. Thereby, it is possible to prevent the electrons supplied from the neutralizer from being attracted to the ion gun 51 side.

  In FIG. 1, the configuration in which the positive voltage of the beam power source is applied to the divided acceleration grids 116 a and 116 b has been described as an example, but the configuration is not limited thereto. For example, as shown in FIG. 14, the divided acceleration grids 116a and 116b may be connected to the positive electrode side of the beam power source via another power source. Further, as shown in FIG. 15, the divided acceleration grids 116a and 116b may be connected to the positive electrode side of the beam power source via a resistor. With the configuration shown in FIGS. 14 and 15, the potential of the divided acceleration grids 116 a and 116 b becomes higher than the potential of the shielding grid, and the effect of suppressing ion beam leakage is further enhanced. Alternatively, as shown in FIG. 16, a separate power source may be provided to apply a voltage to the divided acceleration grids 116a and 116b. Further, in FIG. 1, the case where the negative voltage of the acceleration power supply is applied to the deceleration grid 117 has been described as an example. However, as shown in FIG. 17, a separate power supply is provided to apply the negative voltage to the deceleration grid 117. It may be. Further, a divided acceleration grid for stopping the ion beam may be connected to the positive electrode side of the discharge power source so as to have the same potential as the anode.

  Moreover, although the example which applies a negative voltage to the deceleration grid 117 and the positive voltage to the division | segmentation acceleration grids 116a and 116b was demonstrated to FIG. 1, FIG. 14-FIG. 16, connection of a power supply etc. are not restricted to the example of illustration, What is necessary is just to select suitably.

  In the above embodiment, the ion gun 11 for generating and irradiating the two ion beams Ia and Ib and the frequency adjusting device using the ion gun 11 have been described. However, the number of ion beams irradiated by the ion gun is arbitrary. For example, the number of beams may be four, and the number of crystal resonators to be processed simultaneously may be four.

  In this case, for example, in order to generate sufficient ions, the number of filaments is increased from the configuration of FIG. 1, and the acceleration grid 116 is, for example, as illustrated in FIGS. A beam hole group is formed in each of the four patterns. Further, a divided acceleration grid control switch is connected to each divided acceleration grid. With such a configuration, it is possible to generate four ion beams, process the four crystal resonators in parallel, and stop the irradiation in order from the ion beam that has been processed.

  In the above embodiment, the present invention has been described by taking an example of an adjustment device that adjusts (changes) the resonance frequency by etching the metal electrode of the crystal resonator, but the object of etching and adjustment is arbitrary. For example, the present invention can be applied when etching electrodes of piezoelectric devices other than a crystal resonator. Further, an object to be etched and its material are arbitrary, and for example, metal, semiconductor, resin and the like can be etched.

  In the above embodiment, Ar ions are used as sputtering ions, but other ions can naturally be used.

  Further, in each of the above-described embodiments, only an example in which each group of beam holes is configured to be porous is shown, but the present invention can also be implemented with a single hole. Further, the planar shape of each beam hole is not limited to a circular diameter, and may be an ellipse or a polygon.

1 is an overall configuration diagram of a frequency adjustment device according to a first embodiment of the present invention. It is a disassembled perspective view of the frequency adjusting device shown in FIG. It is a figure which shows the structure of a grid. It is XX-XX sectional view taken on the line of the grid shown in FIG. It is a flowchart for demonstrating operation | movement of a control part. It is a figure which shows the structural example of the apparatus which measured the collector current. It is a figure which shows the relationship between a collector voltage and a collector current. It is a figure which shows the result of having measured the beam leak in case the electric current value of a neutralizer is large and the electric potential of the off-side division | segmentation acceleration grid is the electric potential of a vacuum chamber. It is a figure which shows the result of having measured the electric potential of the off-side division | segmentation acceleration grid by changing the neutralizer emission electric current value by setting the off-side division | segmentation acceleration grid as a floating potential. (A) is a figure which shows the result of having measured the frequency change (DELTA) F of the crystal oscillator by the case where both beams are turned on after applying a negative voltage to a deceleration grid, and the case where one is turned off. b) is a diagram showing the results of measuring the frequency change ΔF of the crystal resonator when both beams are turned on and one of the beams is turned off after the deceleration grid is connected to the ground. (A) And (b) is a figure which shows the example which connects the crystal oscillator which is the irradiation object of an ion beam to a measuring device. It is a figure which shows the modification of this invention. It is a figure which shows the reflector shown in FIG. It is a figure which shows the modification of this invention. It is a figure which shows the modification of this invention. It is a figure which shows the modification of this invention. It is a figure which shows the modification of the pattern of an acceleration grid.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11,51 Ion gun 12 Placement part 13 Resonance frequency measurement part 14 Control part 15 Shutter 15a, 15b Shutter 21 Beam hole group 111 Main body (chamber)
112 Anode (electrode)
113 Filament 114 Gas introduction part 115 Shielding grid 116 Acceleration grid 116a to 116d Split acceleration grid 117 Deceleration grid 125 Neutralizer 131 Filament power supply 132 Discharge power supply 133 Beam power supply 134 Acceleration power supply 141a, 141b Acceleration grid control switch 142 Acceleration grid off switch 143 Acceleration grid on switch 144 Deceleration grid control switch 145 Beam power switch 201a-201b Crystal oscillator 611-613 Beam hole Ia, Ib Ion beam 151 Reflector

Claims (14)

A charged particle irradiation apparatus for irradiating charged particles,
Charged particle generating means for generating charged particles;
An acceleration grid having a plurality of divided grids for extracting the charged particles generated by the charged particle generating means and outputting a charged particle beam;
Control means for individually controlling the potential of the acceleration grid divided into a plurality of parts,
When the charged particle beam is cut off, the divided grid that cuts off the charged particle beam has a first potential higher than a potential of a vacuum chamber in which the charged particle irradiation device is disposed. Irradiation device. A shielding grid is provided between the charged particle generating means and the acceleration grid,
The charged particle irradiation apparatus according to claim 1, wherein the first potential is the same as or higher than the potential of the shielding grid.   The charged particle irradiation apparatus according to claim 1, further comprising a first power source that applies the first potential. A deceleration grid is provided on the charged particle beam output side of the acceleration grid,
The charged particle irradiation apparatus according to claim 1, wherein the deceleration grid has a second potential lower than a potential of the vacuum chamber. A deceleration grid is provided on the charged particle beam output side of the acceleration grid,
The charged particle irradiation apparatus according to claim 1, further comprising a reflector installed outside the deceleration grid.   The charged particle irradiation apparatus according to claim 5, wherein the reflector has a second potential lower than a potential of the vacuum chamber. A neutralizer for neutralizing the charge of the charged particle beam;
The charged particle irradiation apparatus according to claim 4, wherein the second potential is the same as or lower than that of the negative electrode side of the neutralizer.   The charged particle irradiation apparatus according to claim 4, further comprising a second power source that applies the second potential.   The charged particle irradiation apparatus according to claim 1, further comprising a neutralizer that neutralizes charges of the charged particle beam.   The said control means is provided with the switch circuit separately installed between each said division | segmentation grid and said 1st power supply, and the means to turn on / off the said switch circuit separately, The said control circuit is provided. The charged particle irradiation apparatus according to 1. An ion gun comprising the charged particle irradiation device according to any one of claims 1 to 10,
An arrangement means for arranging a plurality of piezoelectric devices;
Resonance frequency discrimination means for discriminating resonance frequencies of a plurality of piezoelectric devices arranged by the arrangement means;
With
While the resonance frequency discriminating means monitors the resonance frequency of the plurality of piezoelectric devices arranged by the arrangement means, the plurality of piezoelectric devices are irradiated with an ion beam in parallel to at least part of each piezoelectric device. A frequency adjusting apparatus, wherein the resonance frequency of the plurality of piezoelectric devices is adjusted by etching. Generate charged particles by a charged particle generating means in a predetermined container arranged inside the vacuum chamber,
An acceleration grid having a plurality of divided grids for extracting the charged particles generated by the charged particle generating means and outputting a charged particle beam is disposed,
A voltage gradient is formed in a direction in which charged particles are extracted by applying a voltage to each accelerating grid, and charged particles in the plasma are ejected as a charged particle beam,
Individually controlling the potential of the acceleration grid divided into a plurality of parts,
A charged particle control method characterized by shielding the emission of the charged particle beam by setting the acceleration grid to a first potential higher than the potential of the vacuum chamber. A shielding grid is provided between the charged particle generating means and the acceleration grid,
The charged particle control method according to claim 12, wherein the first potential is equal to or higher than the potential of the shielding grid. A deceleration grid is arranged outside the acceleration grid,
The charged particle control method according to claim 12 or 13, wherein the deceleration grid is set to a second potential lower than the potential of the vacuum chamber.

Images