JP2007250523A - Charged particle irradiation device and charged particle control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To independently turn on/off a plurality of ion beams. <P>SOLUTION: An ion gun 11 introduces Ar gas from a gas introduction part 114 into a body 111, 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 given to divided acceleration grids 116a and 116b having two divided structures in a direction for emitting ions to emit ions. By independently turning on/off acceleration control switches 121a and 121b, the potentials of the divided acceleration grids 116a and 116b are independently controlled to bring the potential of the divided acceleration grids 116a or 116b corresponding to the ion beam to be stopped into a floating state, and the ion beam is stopped. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a charged particle irradiation apparatus that irradiates charged particles such as ions, and more particularly to a charged particle irradiation apparatus and method capable of independently controlling a plurality of charged particle beams.

  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. For example, Patent Literature 1 and Patent Literature 2 disclose a frequency adjustment method using ion beam etching.

  As shown in FIG. 12, the conventional ion gun for frequency adjustment includes a main body 811, an anode 812, a filament 813, a gas introduction part 814, a shielding grid 815, an acceleration grid 816, a plurality of DC power supplies, , Composed of.

  With such a configuration, Ar gas, for example, is introduced into the main body 811 as a discharge gas from the gas introduction unit 814, the filament 813 is energized and heated, and Ar plasma is generated by direct current hot cathode discharge between the filament 813 and the anode 812. And a high voltage is applied to the acceleration grid 816 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 the mounting table 822. Irradiate the crystal resonator 821.

  The shielding grid 815 and the acceleration grid 816 are formed with a beam hole group including a plurality of beam holes (drawing ports). When one group of beam hole groups is formed in a pattern as shown in FIG. 13, as shown in FIG. 14, the ion current density distribution is such that the center is the strongest and gradually decreases from there to the periphery. One ion beam is formed. FIG. 14 shows the ion current density at the substrate position to be etched, and represents the distance from the origin with the position facing the center of the ion gun as the origin.

  Recently, with the aim of saving the space of the apparatus and shortening the processing time, a plurality of ion beams having an ion current density distribution as shown in FIG. Processing a plurality of crystal resonators has been performed. FIG. 17 shows the ion current density at the substrate position to be etched, and represents the distance from the origin with the position facing the center of the ion gun as the origin.

As shown in FIG. 15, the basic configuration of an ion gun that irradiates a plurality of ion beams is the same as the ion gun for one ion beam shown in FIG. However, in order to generate a plurality of ion beams, as shown in FIG. 16, a shielding grid 815 and an acceleration grid 816 in which a plurality of beam hole groups (two groups in the figure) are formed are arranged.
JP 2000-323442 A JP 2003-298374 A

  The time required for frequency adjustment is determined by the deviation of the frequency of the crystal resonator with respect to the target frequency, and is different for each crystal resonator 821 to be adjusted. For this reason, when the two crystal resonators 821 are adjusted in parallel, the frequency adjustment is completed at different timings. For this reason, it is necessary to prevent the beam from hitting the electrode of the crystal resonator 821 whose frequency has been adjusted first. However, conventionally, control such as stopping only one of the ion beams cannot be performed. For this reason, a mechanical shutter 823 is arranged, and the ion beam to the crystal resonator 821 that has been adjusted is blocked by the mechanical shutter 823.

  However, in such a configuration, the mechanical shutter 223 is sputtered by the blocked ion beam and accumulates as particles in the vacuum chamber, and the shutter is consumed, and it is necessary to periodically replace them and to remove the particles. So it was bothering the hands of the operator.

  In addition, the quality of the crystal unit has been lowered by the particles floating in the tank adhering to the element.

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

  Further, in the conventional configuration, the intensity of the plurality of ion beams is common, and it is difficult to perform processing with many variations.

The present invention has been made in view of the above circumstances, and an object thereof is to enable control of a plurality of charged particle beams independently.
Another object of the present invention is to provide a charged particle beam irradiation apparatus that is easy to operate and maintain.

In order to achieve the above object, the charged particle irradiation apparatus of the present invention comprises:
Charged particle generating means for generating charged particles;
A plurality of divided acceleration grids for extracting the charged particles generated by the charged particle generating means and outputting a charged particle beam;
Control means for independently controlling the intensity of the corresponding charged particle beam by individually controlling the potential of the acceleration grid divided into a plurality of parts;
It is characterized by providing.

  You may arrange | position the electroconductive shielding board for shielding the electric field produced between the divided acceleration grids. This shielding board is comprised from the deceleration grid arrange | positioned on the outer side of the said acceleration grid, for example.

  A shielding grid arranged inside the acceleration grid and a deceleration grid arranged outside the acceleration grid are further arranged to form a three-layered grid configuration of the shielding grid, the acceleration grid, and the deceleration grid. It is desirable.

  The area of the acceleration grid beam hole formed in the acceleration grid may be smaller than the area of the shielding grid beam hole formed in the shielding grid.

  A shielding grid disposed inside the acceleration grid, wherein the acceleration grid and a beam hole group including a plurality of beam holes are formed in the shielding grid, and an area of at least one beam hole formed in the acceleration grid is The area of the corresponding beam hole formed in the shielding grid may be smaller.

  The area of the acceleration grid beam hole of the acceleration grid may be 0.2 to 0.8 times the area of the shield grid beam hole of the shield grid.

  The control means blocks the corresponding charged particle beam, for example, by independently controlling the divided acceleration grid to a floating potential.

  The control means includes, for example, switch circuits individually installed between each of the divided acceleration grids and a power supply, and means for individually turning on / off the switch circuits.

  The deceleration grid is set to the same potential as the vacuum chamber.

  A means for arranging a workpiece to be processed by irradiation with the charged particle beam may be provided. In this case, a beam hole group consisting of a plurality of beam holes is formed in the acceleration grid, and the interval between the beam hole groups arranged in the acceleration grid is relative to the arrangement interval of the workpieces arranged by the arrangement means. It is formed 0.5 to 1.0 times.

  From an ion gun composed of the charged particle irradiation apparatus having the above configuration, an arrangement means for arranging a plurality of piezoelectric devices, and a resonance frequency discrimination means for discriminating the resonance frequencies of the plurality of piezoelectric devices arranged by the arrangement means, At least a part of each piezoelectric device is irradiated by irradiating the plurality of piezoelectric devices with an ion beam in parallel while monitoring the resonance frequency of the plurality of piezoelectric devices arranged by the arranging means by the resonance frequency determining means. You may comprise the frequency adjustment apparatus which adjusts the resonant frequency of several this piezoelectric device by etching.

In addition, the charged particle control method according to the present invention includes:
Generate plasma in a given container,
Arranging a plurality of acceleration grids adjacent to the plasma;
A voltage gradient is formed in a direction in which charged particles are extracted by applying a voltage to each acceleration grid, and charged particles in the plasma are ejected,
By controlling the voltage of the plurality of acceleration grids independently, the ion current density distribution of the ejected charged particles is controlled.
It is characterized by that.

  According to the present invention, the charged particle beam can be controlled by controlling the voltage applied to each of the divided acceleration grids.

  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 frequency adjustment device according to a first embodiment of the present invention is shown in FIGS. As shown in the figure, the frequency adjusting device includes an ion gun 11, a mounting unit 12 that mounts a crystal resonator to be processed, a resonance frequency measuring unit 13 that detects a resonance frequency of the crystal resonator, and a control unit 14. And the shutter 15.

  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 part 114, a shielding grid 115, and an acceleration grid 116. (116a, 116b), a deceleration grid 117, a filament power supply 131, a discharge power supply 132, a beam power supply 133, an acceleration power supply 134, a neutralizer 125, acceleration control switches 121a, 121b, and beam switches 122, 123.

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 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 21 of the beam holes 211 are formed at a distance d.

  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 acceleration grids 116a and 116b are combined. Hereinafter, the entire divided acceleration grids 116a and 116b are collectively referred to as an acceleration grid 116, and individual semi-disc-shaped grids are referred to as divided acceleration grids 116a and 116b.

  As shown in FIG. 3B, beam holes 212 are formed in the acceleration grid 116 at positions that overlap the beam holes 211 formed in the shielding grid 115. A beam hole group for one beam output is arranged in one divided acceleration grid 116a, 116b.

  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. The deceleration grid 117 is connected to the ground. The function of shielding the electric field in the space (the electric field in the direction orthogonal to the ion beam) generated between the two divided acceleration grids by the potential difference between the divided acceleration grids 116a and 116b, and reducing the interaction between the divided acceleration grids 116a and 116b. Have

  As shown in FIG. 3C, the beam holes of the shielding grid 115, the acceleration grid 116, and the deceleration grid 117 are formed and arranged so that their positions overlap.

  1 and 2, the acceleration control switch 121a is connected between the negative electrode of the acceleration power supply 134 and the divided acceleration grid 116a, and is turned on / off by a control signal from the control unit 14. The acceleration control switch 121b is connected between the negative electrode of the acceleration power supply 134 and the divided acceleration grid 116b, and is turned on / off by a control signal from the control unit 14.

  The beam switches 122 and 123 give a potential difference between the anode 112 and the acceleration grid 116.

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.
The acceleration power supply 134 applies a negative voltage to the divided acceleration grids 116a and 116b.

  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 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 control switches 121a and 121b are on / off controlled in accordance with 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.

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 switches 122 and 123 are turned on (at this time, the acceleration control switches 121a and 121b are in the on state), and a high voltage is applied between the anode 112 and the acceleration grid 116. 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.

  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. 4 after a process process start. In FIG. 4, 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, the acceleration control switch 121a is opened and the mechanical shutter 15a is closed. If the frequency adjustment is not completed (step S11; NO), the acceleration control switch 121a is closed (step S12), the mechanical shutter 15a is opened (step S13), and the frequency adjustment of the crystal resonator 201a 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 control switch 121a is opened (step S15). By opening the acceleration control switch 121a, the divided acceleration grid 116a is in an electrically floating state. Thereby, the ion beam Ia irradiated from the divided acceleration grid 116a becomes very weak without substantially affecting the intensity of the ion beam Ib irradiated from the divided acceleration grid 116b.

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). Initially, the acceleration control switch 121b is opened and the mechanical shutter 15b is closed. If the frequency adjustment is not completed (step S17; NO), the acceleration control switch 121b is closed (step S18), the mechanical shutter 15b is opened (step S19), and the frequency adjustment of the crystal resonator 201b 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 control switch 121b is opened (step S21). By opening the acceleration control switch 121b, the divided acceleration grid 116b is in an electrically floating state. Thereby, the ion beam Ib irradiated from the divided acceleration grid 116b becomes very weak without substantially affecting the intensity of the ion beam Ia irradiated from the divided acceleration grid 116a. 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, the intensity of the ion beams Ia and Ib irradiated from the ion gun 11 can be controlled by turning the acceleration control switches 121a and 121b on and off, and the processing of each crystal resonator can be terminated at an appropriate timing. it can.

  Next, the point that irradiation of any one ion beam Ia or Ib can be suppressed by turning off the acceleration control switches 121a and 121b will be described in more detail.

  FIG. 5 shows the current density distribution of the ion beams Ia and Ib obtained under the conditions of the beam power supply voltage of 300 V and the discharge power supply current of 100 mA obtained by the ion gun 11. In this embodiment, the crystal resonator 201 to be processed is arranged 25 mm away from the ion beam extraction port, and FIG. 5 shows the ion current density distribution at a position 2 mm away from the ion beam extraction port. . The horizontal axis shows the distance from the origin when the position facing the center of the ion gun is the origin. This graph shows that the potential on one side of the two divided acceleration grids 116a and 116b is about -20% of the beam voltage, that is, -60V constant with respect to the beam voltage of 300V, and the potential on the other side is accelerated potential by a DC stabilized power supply. This shows the change in beam intensity when changing gradually from -60V.

From FIG. 5, it can be seen that the peak of the ion beam on one side decreases with the change in acceleration potential. Furthermore, the beam was cut off best when disconnected from the DC power supply and floated.
That is, it can be seen that the ion gun 11 can independently control irradiation and blocking of the ion beams Ia and Ib by controlling the divided acceleration grid 116a or 116b to be floating.

  FIG. 6 shows changes in the intensity of the ion beam when a DC stabilizing power source is connected to the deceleration grid 117 and the potential of the deceleration grid 117 is changed under the conditions of a beam power supply voltage of 300 V and a discharge power supply current of 100 mA. . The ion current density was measured at a position 2 mm away from the ion beam outlet. The horizontal axis of the figure shows the distance from the origin when the position facing the center of the ion gun is the origin. Note that the potential of one divided acceleration grid 116a was −60 V, the other divided acceleration grid 116b was floating, that is, the ion beam Ia was turned on and Ib was turned off.

  As a result, the maximum value of the peak of the ion current density was obtained when the potential became 0V. Further, the cutoff characteristic of the beam that is turned off does not change. Therefore, it was confirmed that sufficient beam intensity can be obtained by connecting the deceleration grid 117 to the ground.

  FIG. 7 shows the distribution of ion current density when the deceleration grid 117 is attached and removed. The ion current density was measured at a position 25 mm away from the ion beam outlet. The horizontal axis of the figure shows the distance from the origin when the position facing the center of the ion gun is the origin. Similar to FIG. 6, the ion beam Ia was turned on and Ib was turned off. As a result, when the deceleration grid 117 is not attached, the straightness of the ion beams Ia and Ib is impaired by the peripheral electric field (electric field in the direction orthogonal to the ion beam) generated by the potential difference between the two divided acceleration grids 116a and 116b. The ion current density at the position of the crystal resonator 201 to be processed drops to about 1/100, but it was confirmed that the reduction grid 117 is alleviated to the extent that there is no practical problem.

  Further, when a plurality of beam hole groups 21 are arranged, the relationship between the pitch d and the beam width was obtained. FIG. 8 shows the relationship between the pitch of the grid pattern shown in FIG. 3 and the beam width shown in FIG. As shown in FIG. 8, it can be said that the pitch d and the beam width have a linear relationship. It is easy to express the relationship between the pitch and the beam width in this way, and the relationship between the beam width and the pitch varies depending on the divergence angle of the ion gun plasma, but the optimum pitch is 0.5 to 1 for a desired beam width. A value between times.

  As described above, according to the frequency adjusting apparatus according to this embodiment, a plurality of crystal beams 201a and 201b can be processed in parallel by irradiating a plurality of ion beams from the ion gun 11. Further, the ion beams Ia and Ib applied to the crystal resonators 201a and 201b that have been processed (adjusted) earlier can be turned on / off independently. Therefore, it is possible to reduce the consumption of the shutters 15a and 15b, and the generation of particles can be reduced.

  Furthermore, an ion beam having an appropriate width can be obtained by setting the pitch of the beam hole group 21 to a value 0.5 to 1 times the required beam width.

  Further, it is not necessary to increase the shutter 15 speed in order to obtain high frequency adjustment accuracy, and the shutter structure can be driven by air instead of the solenoid type. In this case, since the friction of the mechanical connection part of the shutter 15 and the heat generation by the solenoid coil are eliminated, the shutter structure and the surrounding cooling structure can be simplified, and the space efficiency of the apparatus can be increased, so that space saving of the apparatus is expected. it can.

  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, as shown in FIG. 9, 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 that in the configuration of FIG. 1, and the acceleration grid 116 is divided into, for example, four parts, and a beam hole group is formed in each. Moreover, each division | segmentation acceleration grid 116a-116d is connected to an acceleration power supply via the acceleration control switches 121a-121d. With such a configuration, four ion beams are generated, the crystal resonators 201a to 201d are processed in parallel, and the corresponding acceleration control switch is turned off in order from the processed ion beam. The irradiation can be stopped.

  Further, the number of ion beams is not limited to 2 and 4, and is arbitrary and may be an odd number. In these cases, the acceleration grid is divided in an arbitrary pattern, for example, as illustrated in FIGS.

In the above-described embodiment, the example in which the ion beam is turned on / off by turning on / off (floating) the voltage applied to the divided acceleration grid has been described. However, the voltage applied to each divided acceleration grid is controlled. By doing so, the intensity of each ion beam may be changed continuously or stepwise (as shown in FIGS. 5 and 6). In this case, for example, as shown in FIG. 11, instead of the switch group, a voltage control unit 141 for applying an arbitrary voltage to each divided acceleration grid is arranged, and the output voltage is controlled by a microcomputer or the like. Also good. According to such a configuration, not only on / off of the ion beam but also processing with different beam intensities can be performed.
Moreover, when simultaneously adjusting a plurality of elements with the same ion gun, the frequency adjustment rate can be changed for each element.

(Second Embodiment)
A frequency adjustment apparatus according to a second embodiment of the present invention will be described with reference to the drawings. The frequency adjustment device of the present embodiment is different from the device of the first embodiment in that the area of the acceleration grid of the ion gun constituting the frequency adjustment device is formed smaller than the area of the shielding grid. . Hereinafter, the same reference numerals are assigned to the parts common to the first embodiment, and detailed description thereof is omitted.

  FIG. 18 shows a configuration example of the frequency adjusting device according to the present embodiment. Similar to the first embodiment, the frequency adjusting device of the present embodiment includes an ion gun 51, a mounting unit 12 on which a crystal resonator to be processed is mounted, and a resonance that detects a resonance frequency of the crystal resonator. The frequency measuring unit 13, the control unit 14, and the shutter 15 are included.

  The ion gun 51 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 515, and an acceleration grid. 516 (516a, 516b), deceleration grid 517, filament power supply 131, discharge power supply 132, beam power supply 133, acceleration power supply 134, neutralizer 125, acceleration control switches 121a, 121b, beam switch 122, 123.

  The shielding grid 515 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 51 outputs two beams, and its grid pattern has a structure 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.

  The acceleration grid 516 is disposed substantially parallel to the ion emission surface of the main body 111 at a predetermined distance from the shielding grid 515. As shown in FIG. 19B, the acceleration grid 516 has a shape in which a disc is divided into two. In other words, the acceleration grid 516 has a structure in which two semi-disc-shaped divided acceleration grids 516a and 516b are combined in the same manner as in the first embodiment. In the acceleration grid 516, as shown in FIG. 19B, beam holes 612 are formed at positions overlapping the beam holes 611 formed in the shielding grid 515. The area of the beam hole 612 of the acceleration grid 516 is formed smaller than the area of the beam hole 611 of the shielding grid 515. In addition, a beam hole group for outputting one beam is arranged in one divided acceleration grid 516a, 516b.

  The deceleration grid 517 is disposed substantially parallel to the ion emission surface of the main body 111 close to and away from the acceleration grid 516. The deceleration grid 517 has the same configuration as the shielding grid 515 as shown in FIG. In the present embodiment, the area of the beam hole 613 of the deceleration grid 517 is formed to be approximately the same as the area of the beam hole 611 of the shielding grid 515. The deceleration grid 517 is connected to the ground, shields the electric field in the space (electric field in the ion beam orthogonal direction) generated between the two divided acceleration grids by the potential difference between the divided acceleration grid 516a and the divided acceleration grid 516b. It has a function of reducing the interaction between the acceleration grids 516a and 516b.

  Further, in the present embodiment, the shielding grid 515, the acceleration grid 516, and the deceleration grid 517 are spaced apart from each other substantially in parallel as shown in FIG. The separation distance between the shielding grid 515 and the acceleration grid 516 and the separation distance between the acceleration grid 516 and the deceleration grid 517 are substantially the same. Specifically, in the present embodiment, the distance is substantially the same as the diameter of the beam hole. They are spaced apart. In particular, in the present embodiment, as shown in FIG. 20, the area of the beam hole 611 provided in the shielding grid 515 and the area of the beam hole 613 provided in the deceleration grid 517 are substantially the same size. Although formed, the area of the beam hole 612 provided in the acceleration grid 516 is formed smaller than the area of the beam hole 611.

  In the present embodiment, the area of the beam hole 612 of the acceleration grid 516 is formed 0.2 to 0.8 times the area of the beam hole 611 of the shielding grid 515 as will be described in detail below. Thus, by forming the beam hole 612 of the acceleration grid 516 to be smaller than the beam hole 611 of the shielding grid 515, when one of the divided acceleration grids 516a and 516b is turned off, the other divided acceleration is performed. The leakage of the beam from the grid can be suppressed satisfactorily.

  FIG. 21 shows that the beam power supply voltage is 900 V, the discharge power supply current is 650 mA, the diameters of the beam holes 611 and 613 of the shielding grid 515 and the deceleration grid 517 are φ1.1 mm, and the diameter of each beam hole of the acceleration grid is shown. Is a distribution of ion current density in a case of a circle of φ1.1 mm, φ1.0 mm, φ0.8 mm, φ0.6 mm, and φ0.4 mm. In the ion beam, Ia was turned on and Ib was turned off as in FIG. The horizontal axis shown in FIG. 21 indicates the distance from the origin when the position facing the center of the ion gun is the origin, and the vertical axis is the maximum value of the ion current density distribution obtained at the hole diameter of each acceleration grid. Intensity is expressed as a percentage.

  When the beam voltage is high in this way, the ion beam Ib is not completely zero due to the electric field generated by the potential difference between the plasma and the deceleration grid, and a leaking beam is generated. For example, as shown in FIG. 21, in the case of φ1.1 mm where the beam hole of the acceleration grid and the beam hole of the shielding grid are the same, Ib is about 40% with respect to the ion beam Ia, and a leakage beam is generated. I understand that. However, when the inner diameter of the accelerating grid is reduced to φ1.0 mm, φ0.8 mm, φ0.6 mm, and φ0.4 mm, the leakage of the ion beam gradually decreases, and at φ0.6 mm and φ0.4 mm, 5% It can be seen that it decreases to the extent. Therefore, as is clear from FIG. 21, the beam hole of the acceleration grid is compared with the beam hole of the shielding grid, and if it is formed small, the electric field generated by the potential difference between the plasma and the deceleration grid is reduced, and ion beam leakage is reduced. Can do.

Next, as in FIG. 21, under the conditions of a beam power supply voltage of 900 V and a discharge power supply current of 650 mA, the diameters of the beam holes 611 and 613 of the shielding grid 515 and the deceleration grid 517 are made to be circular of φ1.1 mm, and the acceleration grid The diameter of each beam hole is φ1.1mm, φ1.0mm, φ0.8mm, φ0.6
FIG. 22 shows the ratio of the ion current density between the ion beams Ia and Ib in the case of a circle of mm and φ0.4 mm. The ion beam Ib is in an off state. In FIG. 22, the horizontal axis represents the beam hole area of the acceleration grid with respect to the beam hole area of the shielding grid, and the vertical axis represents the ratio of Ib to the ion current density Ia (Ib / Ia).

  From FIG. 22, when the ratio of the beam hole area of the accelerating grid to the beam hole area of the shielding grid is 30% or less, Ib / Ia is almost flat at about 5%, and when it exceeds 30%, Ib / Ia gradually increases. It increases almost linearly, and when it reaches 100%, Ib / Ia reaches about 40%. When processing a crystal resonator as in the present embodiment, the current density of the off-side ion beam with respect to the on-side current density is not affected so as not to affect the workpiece on the side where the ion beam is off. The ratio is preferably 25% or less. Therefore, it can be seen from the graph shown in FIG. 22 that the beam hole diameter of the acceleration grid should be set to 80% or less with respect to the beam hole area of the shielding grid.

  Next, FIG. 23 is a graph showing the current density when both the ion beams Ia and Ib are turned on under the same conditions as the graph shown in FIG. In FIG. 23, the horizontal axis represents the area ratio of the beam holes, and the vertical axis represents the ion current density when both Ia and Ib are turned on.

From FIG. 23, it is understood that the ion current density is maintained at 8 mA / cm ² or more until the area ratio of the beam holes is 30%, but the ion current density is remarkably lowered when it is 20% or less. In particular, under the condition where the beam power supply voltage is 900V, the ion current density is required to be 6 mA / cm ² or more for practical use. If the area ratio of the beam holes is too small, the value will be lower and the processing speed of the apparatus will be reduced. There is a delay. Therefore, it can be said that the area ratio of the beam holes needs to be 20% or more in order to obtain a sufficient intensity of the ion beam.

  Thus, in order to obtain the effect of suppressing the leakage of the ion beam, it is preferable to make the beam hole of the acceleration grid small. However, if the beam hole is made too small, the intensity of the ion beam in the on state is weakened. Become. Therefore, it is preferable to set the area ratio of each beam hole to 0.2 to 0.8 times in order to suppress the leakage in the off state and further ensure the current intensity in the on state. In this embodiment, the beam power supply voltage is 900V as an example. However, in order to suppress the leakage of the beam and to secure the ion beam intensity, the power supply voltage is not limited to this. The area ratio of the holes is preferably 0.2 to 0.8 times.

  As described above, in the frequency adjusting device according to the present embodiment, the beam hole of the acceleration grid is formed smaller than the beam hole of the shielding grid, so that the ion beam density on the off side can be reduced without deteriorating the intensity of the ion current density on the on side. Therefore, it is possible to obtain a good on / off characteristic of the ion beam.

  In the present embodiment, the ion gun 11 that generates and irradiates the two ion beams Ia and Ib is taken as an example, but the number of ion beams that the ion gun irradiates is arbitrary. It is not limited to 2 and 4, and is arbitrary and may be an odd number. Also in this embodiment, the voltage applied to each divided acceleration grid is controlled by turning on / off (floating) the voltage applied to the divided acceleration grid, not limited to the case where the ion beam is turned on / off. Thus, the intensity of each ion beam may be changed continuously or stepwise (as shown in FIGS. 5 and 6). Moreover, when simultaneously adjusting a plurality of elements with the same ion gun, the frequency adjustment rate can be changed for each element.

  In this embodiment, the beam hole group formed in the acceleration grid corresponds to the beam hole group formed in the shielding grid, and the beam holes of the acceleration grid are all smaller than the beam holes of the corresponding shielding grid. However, it is sufficient that at least one of the beam holes of the acceleration grid is smaller than the beam hole of the corresponding shielding grid. For example, the beam hole of the acceleration grid may be smaller than the beam hole of the shielding grid only at the center of the beam hole group, and the peripheral part of the beam hole group may have the same size as the acceleration grid and the shielding grid.

  In addition, this invention is not limited to the said embodiment, A various change and application are possible. For example, 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 a metal electrode of a crystal resonator. However, the object of etching and adjustment is arbitrary. is there. 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, the present invention is not limited to ions and can be applied to electrons.

  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 the grid which concerns on the 1st Embodiment of this invention. It is a flowchart for demonstrating operation | movement of a control part. It is a graph which shows the relationship between the voltage applied to a division | segmentation acceleration grid, and ion beam intensity. It is a graph which shows the relationship between the voltage applied to a deceleration grid, and ion beam intensity. It is a graph which shows the relationship between the presence or absence of a deceleration grid, and ion beam intensity. It is a graph which shows the relationship between a grid pitch and the width | variety of an ion beam. It is a figure which shows the example of an apparatus structure when the number of ion beams is set to 4. It is a figure which shows the example of the pattern of an acceleration grid. It is a figure which shows the example of an apparatus structure when it is set as the structure which can vary the intensity | strength of an ion beam. It is a figure which shows the structural example of the conventional 1 beam type frequency adjusting device. It is a figure which shows the example of the pattern of the acceleration grid used with the apparatus of FIG. It is a graph which shows the example of the current density of the ion beam irradiated with the apparatus of FIG. It is a figure which shows the structural example of the conventional 2 beam type frequency adjustment apparatus. It is a figure which shows the example of the pattern of the shielding grid and acceleration grid which are used with the apparatus of FIG. It is a graph which shows the example of the current density of the ion beam irradiated with the apparatus of FIG. It is a whole block diagram of the frequency adjustment apparatus which concerns on the 2nd Embodiment of this invention. It is a figure which shows the structure of the grid which concerns on the 2nd Embodiment of this invention. It is the XX-XX sectional view taken on the line of the grid shown in FIG. It is a graph which shows the change of the current density at the time of changing the diameter of an acceleration grid. It is a graph which shows the relationship of the ratio (Ib / Ia) of the intensity | strength of an ion beam with respect to the area ratio of a beam hole. It is a graph which shows the relationship of the ion beam intensity with respect to the area ratio of a beam hole.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11,51 Ion gun 12 Mounting part 13 Resonance frequency measurement part 14 Control part 15 Shutter 15a, 15b Shutter 21, 61 Beam hole group 111 Main body (chamber)
112 Anode (electrode)
113 Filament 114 Gas introduction part 115,515 Shielding grid 116,516 Acceleration grid 116a-116d, 516a, 516b Division acceleration grid 117,517 Deceleration grid 121a-121d Acceleration control switch 122,123 Beam switch 125 Neutralizer 131 Filament power supply 132 Discharge Power supply 133 Beam power supply 134 Acceleration power supplies 201a to 201d Crystal resonators 211 and 611 Beam holes Ia and Ib Ion beam

Claims (13)

A charged particle irradiation apparatus for irradiating charged particles,
Charged particle generating means for generating charged particles;
A plurality of divided acceleration grids for extracting the charged particles generated by the charged particle generating means and outputting a charged particle beam;
Control means for independently controlling the intensity of the corresponding charged particle beam by individually controlling the potential of the acceleration grid divided into a plurality of parts;
A charged particle irradiation apparatus comprising:   The charged particle irradiation apparatus according to claim 1, comprising a conductive shielding plate for shielding an electric field generated between the divided acceleration grids.   The charged particle irradiation apparatus according to claim 2, wherein the shielding plate is configured by a deceleration grid disposed outside the acceleration grid.   The charged particle irradiation apparatus according to any one of claims 1 to 3, wherein a shielding grid disposed inside the acceleration grid, and a deceleration grid disposed outside the acceleration grid. A charged particle irradiation apparatus, further comprising a three-layered grid configuration of a shielding grid, an acceleration grid, and a deceleration grid.   The charged particle irradiation apparatus according to any one of claims 1 to 3, comprising a shielding grid disposed inside the acceleration grid, and an area of the acceleration grid beam hole formed in the acceleration grid, A charged particle irradiation apparatus, wherein the charged particle irradiation apparatus is formed smaller than an area of a shielding grid beam hole formed in the shielding grid.   The charged particle irradiation apparatus according to claim 1, further comprising: a shielding grid disposed inside the acceleration grid, wherein the acceleration grid and the shielding grid include a plurality of beam holes. A charged particle irradiation apparatus, wherein a hole group is formed, and an area of at least one beam hole formed in the acceleration grid is smaller than an area of a corresponding beam hole formed in the shielding grid.   The charged particle irradiation apparatus according to claim 5 or 6, wherein an area of the acceleration grid beam hole of the acceleration grid is 0.2 to 0.8 times an area of the shielding grid beam hole of the shielding grid. A charged particle irradiation apparatus characterized by being formed.   8. The charged particle irradiation apparatus according to claim 1, wherein the control unit blocks the corresponding charged particle beam by independently controlling the divided acceleration grid to a floating potential. 9. The charged particle irradiation apparatus characterized by the above.   9. The charged particle irradiation apparatus according to claim 8, wherein the control means includes a switch circuit individually installed between each of the divided acceleration grids and a power source, and means for individually turning on / off the switch circuit. A charged particle irradiation apparatus comprising:   5. The charged particle irradiation apparatus according to claim 3, wherein the deceleration grid has the same potential as the vacuum chamber. It is a charged particle irradiation apparatus of any one of Claims 1-10,
An arrangement means for arranging a workpiece to be processed by irradiation with the charged particle beam;
A beam hole group consisting of a plurality of beam holes is formed in the acceleration grid, and the interval between the beam hole groups arranged in the acceleration grid is 0.5 with respect to the arrangement interval of the workpieces arranged by the arrangement means. A charged particle irradiation apparatus, wherein the charged particle irradiation apparatus is formed in a magnification of 1.0 to 1.0. An ion gun comprising the charged particle irradiation apparatus according to any one of claims 1 to 11,
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
At least a part of each piezoelectric device is irradiated by irradiating the plurality of piezoelectric devices with an ion beam in parallel while monitoring the resonance frequency of the plurality of piezoelectric devices arranged by the arranging means by the resonance frequency determining means. A frequency adjusting apparatus that adjusts resonance frequencies of the plurality of piezoelectric devices by etching. Generate plasma in a given container,
Arranging a plurality of acceleration grids adjacent to the plasma;
A voltage gradient is formed in a direction in which charged particles are extracted by applying a voltage to each acceleration grid, and charged particles in the plasma are ejected,
By controlling the voltage of the plurality of acceleration grids independently, the current density distribution of the injected charged particles is controlled,
The charged particle control method characterized by the above-mentioned.

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