JP6649495B2 - Accelerator, method of operating accelerator, and method of manufacturing semiconductor using accelerator - Google Patents

Description

  Embodiments of the present invention relate to an accelerator having a high-frequency cavity.

  Conventional accelerators include a high-frequency cavity capable of changing the speed of an incident charged particle beam. In such an accelerator, a fundamental wave having a predetermined frequency is generated inside the high-frequency cavity using a high-frequency source, and the charged particle beam is introduced into the high-frequency cavity at a period that is a fraction of the frequency of the fundamental wave. It is made to enter repeatedly.

JP 2008-243375 A

  In a high-frequency cavity, a higher-order mode (HOM) having a higher frequency than the frequency of the fundamental wave used for changing the speed of the charged particle beam may occur. This higher-order mode occurs because the electromagnetic waves generated by the charged particle beam resonate inside the high-frequency cavity. If the higher-order mode coincides with the incident cycle of the charged particle beam, electromagnetic waves serving as noise accumulate inside the high-frequency cavity, causing a problem that the high-frequency cavity generates heat.

  The embodiment of the present invention has been made in view of such circumstances, and has as its object to provide an accelerator technology capable of suppressing heat generation in a high-frequency cavity.

An accelerator according to an embodiment of the present invention includes a high-frequency cavity through which a charged particle beam can pass, a high-frequency source that inputs an electromagnetic wave of a fundamental frequency into the high-frequency cavity, a laser output unit that outputs a laser beam, and the laser beam. A target unit that generates charged particles by being irradiated, a beam extraction unit that extracts a charged particle beam by accelerating the charged particles in one direction, and a random number output unit that outputs a random number corresponding to the cycle of the fundamental frequency An output control unit that performs control to output the charged particle beam toward the high-frequency cavity at the specific timing among the timings corresponding to the cycle of the fundamental frequency, and the output control unit includes: The timing is selected based on the random number output from the random number output unit .

The operation method of the accelerator according to the embodiment of the present invention includes a high-frequency input step of inputting an electromagnetic wave having a fundamental frequency from a high-frequency source to a high-frequency cavity, a laser output step of outputting laser light from a laser output unit, and the laser light being a target. A particle generating step of generating charged particles by irradiating the unit, a beam extracting step of extracting a charged particle beam by accelerating the charged particles in one direction, and outputting a random number corresponding to a cycle of the fundamental frequency. Obtaining the random number from the random number output unit, and an output control step of performing control to output the charged particle beam toward the high-frequency cavity at the specific timing of the timing corresponding to the cycle of the fundamental frequency, see containing and a passing step of said charged particle beam passes through the high-frequency cavity, in the output control step , Characterized in that selected the timing based on the random number obtained from the random number output unit.

  According to an embodiment of the present invention, an accelerator technology capable of suppressing heat generation in a high-frequency cavity is provided.

FIG. 2 is a diagram illustrating an accelerator according to the first embodiment. 5 is a timing chart showing timings of a trigger signal and a laser beam. 5 is a flowchart illustrating an operation method of the accelerator. The figure which shows the accelerator of 2nd Embodiment. 5 is a timing chart showing timings of a trigger signal and a laser beam. 5 is a flowchart illustrating an operation method of the accelerator.

(1st Embodiment)
Hereinafter, the present embodiment will be described with reference to the accompanying drawings. First, a first embodiment will be described with reference to FIGS. 1 is an accelerator for accelerating the charged particle beam B. The accelerator 1 exemplifies a linear accelerator that accelerates the charged particle beam B on a straight line.

  The accelerator 1 also generates a high-frequency cavity 2 through which the charged particle beam B can pass, a high-frequency source 3 that inputs a radio frequency (RF: Radio Frequency), which is an electromagnetic wave of a fundamental frequency, to the high-frequency cavity 2, and generates a charged particle beam B. And a main controller 5 for controlling the high-frequency source 3 and the beam generator 4. In FIG. 1, a simplified configuration is shown for easier understanding, but devices other than these devices may be included in the accelerator 1.

  Further, the high-frequency cavity 2 includes a plurality of cavity chambers 6 each having a shape in which a sphere is flattened. These cavity chambers 6 are arranged side by side along the traveling direction of the charged particle beam B. Further, the center of the cavity 6 is penetrated, and a path through which the charged particle beam B can pass is formed linearly. In addition, the high frequency wave incident into the high-frequency cavity 2 repeats reflection according to the internal shape of the cavity chamber 6. Then, a fundamental wave (standing wave) is generated inside the high-frequency cavity 2.

  Further, a high frequency source 3 is connected to an end of the high frequency cavity 2 via an RF input unit 7. The high-frequency source 3 inputs an electromagnetic wave K (high-frequency K) having a fundamental frequency into the high-frequency cavity 2. The high frequency source 3 includes a high frequency control unit 8 that controls a high frequency K input to the high frequency cavity 2. The high frequency control unit 8 includes a frequency setting unit 9 for setting a basic frequency. As will be described later, the frequency setting unit 9 performs a setting to increase the basic frequency in accordance with a ratio of selecting the pulse of the laser light L within a predetermined period.

  The high frequency cavity 2 receives the high frequency K from the high frequency source 3 to generate a fundamental wave (standing wave) therein. The frequency of the fundamental wave generated inside the high frequency cavity 2 is controlled by the frequency of the high frequency K input from the high frequency source 3.

  Further, the beam generating device 4 repeatedly causes the charged particle beam B to be incident into the high-frequency cavity 2 at a period that is a fraction of the frequency of the fundamental wave. The speed of the incident charged particle beam B is accelerated by appropriately changing the timing of incidence of the charged particle beam B with respect to the standing wave in the high-frequency cavity 2 or the phase of the high frequency K with respect to the timing of incidence of the charged particle beam B. You can slow down and slow down.

  In addition, since the high-frequency cavity 2 generates heat when a fundamental wave is generated, a metal material having high thermal conductivity and low electric resistance is suitable. This high-frequency cavity 2 is made of a superconducting material such as a niobium material. The niobium material includes a simple substance of niobium and an alloy of niobium and another metal (such as copper). Then, the high-frequency cavity 2 is cooled to a very low temperature (about 2K) by a cooling device (not shown). In this way, the cooled high-frequency cavity 2 is transformed into a superconducting state in which the electric resistance is infinitely zero. By setting the high-frequency cavity 2 in the superconducting state, the speed of the charged particle beam B can be changed with high efficiency.

  The beam generating device 4 further includes a laser output unit 10 that outputs the laser light L, a target 11 that generates charged particles by being irradiated with the laser light L, and accelerates the charged particles generated by the target 11 in one direction. The extraction electrode 12 for extracting the charged particle beam B, the DC power supply 13 connected to the target 11 and the extraction electrode 12, and the laser beam L provided between the laser output unit 10 and the target 11 The light modulator 14 includes a light modulator 14 that can be cut off, and an output controller 15 that controls the laser output unit 10 and the light modulator 14. In the first embodiment, the extraction electrode 12 is a beam extraction unit.

  The laser beam L output from the laser output unit 10 is applied to the target 11. Then, charged particles are generated in the target 11. Then, the generated charged particles are accelerated in one direction by the extraction electrode 12 and are incident on the high-frequency cavity 2 as a charged particle beam B.

  The main control unit 5 is connected to the high frequency control unit 8 and the output control unit 15, and controls the high frequency source 3 and the beam generation device 4. The main control unit 5, the output control unit 15, and the high-frequency control unit 8 have hardware resources such as a processor and a memory. When the CPU executes various programs, information processing by software uses the hardware resources. It is composed of a computer realized by using.

  The charged particle beam B incident on the high-frequency cavity 2 from the beam generator 4 is a pulse train beam (pulse wave). Further, the output control unit 15 controls the timing of the output of the charged particle beam B by controlling the timing at which the target 11 is irradiated with the laser light L. In the present embodiment, the charged particle beam B is output at a timing corresponding to the period of the fundamental frequency of the fundamental wave generated inside the high-frequency cavity 2.

  Here, a high-order mode (HOM: Higher Order Mode) generated inside the high-frequency cavity 2 will be described in detail. For example, the frequency component of the high frequency (fundamental wave) existing inside the high frequency cavity 2 is ideally only the frequency of the high frequency K input from the high frequency source 3. However, the acceleration / deceleration of the charged particle beam B is realized by transmitting / receiving the high-frequency energy stored in the high-frequency cavity 2 between the high-frequency cavity 2 and the charged particle beam B. Therefore, when the charged particle beam B is accelerated or decelerated, the high frequency inside the high frequency cavity 2 is disturbed. Then, a frequency component different from the high frequency K input from the high frequency source 3 may be generated inside the high frequency cavity 2.

  For example, the time change of the current of the pulse train of the charged particle beam B can be regarded as a periodic δ function. This has a frequency component that is an integral multiple of the fundamental frequency when Fourier transform is performed. This is the frequency component of the disturbance that the high frequency stored in the high frequency cavity 2 receives.

  In an ideal high-frequency cavity 2, only high-frequency frequencies that can resonate therein are the fundamental wave and a frequency that is an integral multiple of the fundamental wave. On the other hand, since the actual internal shape of the high-frequency cavity 2 has a three-dimensional shape, it has various resonance frequencies in addition to the fundamental frequency. In addition to these fundamental modes, the frequency components of the electromagnetic field generated inside the high-frequency cavity 2 are called higher-order modes.

  As described above, the beam incident on the high-frequency cavity 2 has a frequency that is a fraction of the fundamental frequency. The acceleration or deceleration of the charged particle beam B is the exchange of energy with the high-frequency cavity 2. Since the transmitted and received energy has a frequency due to the charged particle beam B, the higher-order mode of the high-frequency cavity 2 may coincide with one of the frequency components of the charged particle beam B. In this case, electromagnetic waves serving as noise may accumulate inside the high-frequency cavity 2 and the high-frequency cavity 2 may generate heat. This heat generation may cause deformation of the high-frequency cavity 2 or breakage (quench) of the superconducting state. In addition, the charged particle beam B to be accelerated next may be disturbed by electromagnetic waves that become noise, and the charged particle beam B may not be normally accelerated, or may have an adverse effect such that the shape of the charged particle beam B is lost.

  Thus, in the present embodiment, the frequency component of the charged particle beam B is dispersed or attenuated by selecting the pulse train of the charged particle beam B incident on the high-frequency cavity 2 at irregular intervals (thinning out at random). To do. By doing so, the occurrence of higher-order modes is suppressed, and the heat generation of the high-frequency cavity 2 can be suppressed.

  The beam generating device 4 outputs the charged particle beam B to the high-frequency cavity 2 at a specific timing selected from timings at regular intervals corresponding to the cycle of the fundamental frequency. In the first embodiment, the pulse train of the charged particle beam B is selected by selecting the pulse train of the laser light L using the light modulator 14. That is, the selection of the laser beam L and the selection of the charged particle beam B are synonymous.

  Here, the output mode of the charged particle beam B output from the beam generator 4 will be described in detail. The output control unit 15 of the beam generation device 4 has a ratio setting unit 16 that sets a ratio at which a pulse of the laser light L is selected within a predetermined period, and a cycle (tuning timing) at a fixed interval synchronized with the cycle of the fundamental frequency. A tuning unit 17 that outputs a tuning signal U; a signal output unit 18 that outputs a trigger signal G that triggers the laser output unit 10 to output the laser light L; and a random number with a constant interval that tunes to the cycle of the fundamental frequency. A random number output unit 19 for outputting R and a selection unit 20 for outputting a selection signal S for controlling the light modulation unit 14 are provided.

  Further, the light modulation unit 14 of the first embodiment is configured by an optical switch. Note that an optical switch is a device that can switch between passing (ON) and blocking (OFF) light. In the first embodiment, an EО modulator is used as an optical switch. The EO modulator is a device that controls light deflection by electric control and changes the intensity of light by combining an electro-optic crystal and a polarizer. In another embodiment, a MEMS optical switch, a mechanical optical switch, or the like may be used.

  In the first embodiment, the light modulator 14 switches between passing (ON) and blocking (OFF) the laser light L traveling toward the target 11. Note that the optical path between the laser output unit 10 and the target 11 may be constituted by an optical fiber or the like. Thus, the output timing of the charged particle beam B is controlled by controlling the irradiation timing of the laser beam L to the target 11.

  Note that the signal output unit 18 controls the output of the trigger signal G according to the tuning signal U (tuning timing) output from the tuning unit 17. Further, the selection unit 20 controls the output of the selection signal S according to the tuning signal U output from the tuning unit 17 and the random number R output from the random number output unit 19.

  Further, the period at a constant interval synchronized with the period of the fundamental frequency may be the same period as the fundamental frequency, or may be a period that is a fraction of the fundamental frequency. In the following description, the output timing of the tuning signal U output from the tuning unit 17 is assumed to be the same as the period of the fundamental frequency for the sake of understanding.

  As shown in FIG. 2, the periods of the fundamental frequency of the high frequency K input from the high frequency source 3 to the high frequency cavity 2 are T1 to T20. When the charged particle beam B is incident on the high-frequency cavity 2 at a timing corresponding to these periods T1 to T20, the charged particle beam B can be accelerated or decelerated. Here, the tuning unit 17 of the output control unit 15 outputs the tuning signal U at a timing corresponding to the periods T1 to T20 of the fundamental frequency. Further, the signal output unit 18 outputs a trigger signal G according to the tuning signal U. The pulse train of the laser light L output from the laser output unit 10 coincides with the periods T1 to T20 of the fundamental frequency.

  Note that the tuning signal U is also input to the selection unit 20. The random number R output from the random number output unit 19 is input to the selection unit 20. The random number R is a binary random (irregular) value. In the random number output unit 19, a predetermined random number sequence is generated by a random number generator. Further, the random number output unit 19 randomly outputs a numerical value of “0” or “1”. Note that a random value of a decimal number or a hexadecimal number may be output, and the output value may be converted to “0” or “1” to output a random number sequence. The random number R output from the random number output unit 19 is output corresponding to the tuning signal U (the period T1 to T20 of the fundamental frequency).

  Further, the selection unit 20 controls the output of the selection signal S according to the tuning signal U and the random number R. The light modulator 14 controls the passage (ON) and the cutoff (OFF) of the laser light L based on the selection signal S. For example, when the tuning signal U is input and the random number R corresponding to the tuning signal U is “0”, the selection unit 20 uses the light modulation unit 14 to cut off the laser light L. On the other hand, when the random number R corresponding to the tuning signal U is “1”, the selection unit 20 passes the laser light L without blocking the laser light L using the light modulation unit 14.

  The laser beam L cut off by the light modulator 14 is not irradiated on the target 11. On the other hand, the laser beam L not blocked by the light modulator 14 is irradiated on the target 11 to generate a charged particle beam B, and the charged particle beam B is incident on the high-frequency cavity 2.

  That is, the irradiation timing of the laser beam L, that is, the output timing of the charged particle beam B, is controlled by the random number R of the random number output unit 19. Since the irradiation timing of the laser beam L is determined according to the random number R, the pulse train of the charged particle beam B incident on the high-frequency cavity 2 can be selected at irregular intervals. By doing so, the charged particle beam B is output at irregular intervals, so that the generation of higher-order modes inside the high-frequency cavity 2 can be prevented.

  As described above, the interval between the irradiation timing of one laser light L and the irradiation timing of the next laser light L is not constant, but is appropriately changed according to the random number R. That is, in the present embodiment, the interval between the timing at which one charged particle beam B is output and the timing at which the next charged particle beam B is output can be changed. By doing so, the timing at which the charged particle beam B is output repeatedly is shifted, so that the resonance phenomenon inside the high-frequency cavity 2 can be prevented.

  The ratio setting unit 16 sets in advance the ratio at which the irradiation timing of the laser light L is selected within a predetermined period. The random number output unit 19 sets the appearance of the random number R according to the selection ratio set by the ratio setting unit 16. For example, when selecting 50% of the irradiation timing of the laser light L, the appearance probability of “0” in the random number R output by the random number output unit 19 may be set to 50%. The rate at which the irradiation timing of the laser light L is selected within the predetermined period may be changed as appropriate.

  Here, when the charged particle beam B is selected and output, the average current (average energy) of the charged particle beam B decreases. Therefore, in order to obtain a target average current, it is necessary to raise the fundamental frequency by an amount that takes into account the selection ratio in advance. For example, the current component of the pulse train of the charged particle beam B incident on the high-frequency cavity 2 at a specific repetition frequency has a frequency component concentrated at an integral multiple of this frequency. According to Wiener-Khinchin's theorem, the spectrum of the modulation received by the charged particle beam B is expressed by the following equation (1).

  Here, C (t) is an expected value of the autocorrelation function when the beam current is used as a signal sequence. Further, when a pulse train of (fundamental frequency f1) = (1 / interval δt) and each pulse is selected with the probability P, the signal train P (t) is expressed by the following equation (2).

  Here, bn becomes 1 at the probability P and becomes 0 at (1−P). Therefore, the expected value of the autocorrelation is represented by the following Expression 3.

  By substituting this expected value into Equation 1, the following Equation 4 is obtained.

  Here, ω = 2πn / Δt. That is, it has a value only when f = nf1 = n / Δt (it is not zero). Further, it is necessary to supplement the current value of the fundamental frequency f1 by an amount corresponding to the selection of the charged particle beam B. Therefore, the fundamental frequency f1 is higher than the frequency f0 when the present invention is not applied (f1 has a higher frequency than f0). That is, when the charged particle beam B is selected with a probability of 50%, f1 = 2 × f0. Therefore, the higher-order mode generated inside the high-frequency cavity 2 is half of f = f0 × n / Δt when the present invention is not applied, that is, f = f0 × n / 2Δt. Therefore, it is possible to suppress heat generation as a whole without changing the characteristics of the beam current and the beam pulse, and it is possible to suppress heat generation in the high-frequency cavity 2 due to higher-order modes.

  In addition, by increasing the basic frequency f1, the frequency component becomes smaller than the frequency f0 when the present invention is not applied. For example, assume that the frequency of f1 is 1.3 GHz and the frequency of f0 is 650 MHz, which is half the frequency of f1. In this case, the frequency components of f0 are 650 MHz, 1.3 GHz, 1.95 GHz, 2.6 GHz, 3.25 GHz, 3.9 GHz... On the other hand, the frequency components of f1 are 1.3 GHz, 2.6 GHz, 3.9 GHz, and so on. Thus, f1 has less frequency components than f0. Therefore, by raising the fundamental frequency f1, the possibility (probability) that a resonance phenomenon occurs inside the high-frequency cavity 2 can be reduced.

  As shown in FIG. 1, the output control unit 15 sets the selection ratio W of the irradiation timing of the laser light L in the ratio setting unit 16 according to the control information C input from the main control unit 5. Further, the ratio setting unit 16 outputs the set selection ratio W to the frequency setting unit 9 of the high frequency control unit 8. The selection ratio is also output to the random number output unit 19. Further, the frequency setting unit 9 sets a fundamental frequency according to the selection ratio W. The high-frequency control unit 8 performs control by outputting a control signal N to the high-frequency source 3 based on the set fundamental frequency.

  Then, the frequency setting unit 9 outputs the frequency information F of the set basic frequency to the ratio setting unit 16. Further, the ratio setting unit 16 outputs the frequency information F to the tuning unit 17 and the random number output unit 19. Then, the tuning unit 17 and the random number output unit 19 output the tuning signal U and the random number R based on the frequency information F.

  The output control unit 15 can select these timings at random by selecting the irradiation timing of the laser light L based on the random number R output from the random number output unit 19. In addition, the frequency setting unit 9 performs setting to increase the fundamental frequency in accordance with the ratio at which the irradiation timing of the laser light L is selected within a predetermined period, so that the average energy of the charged particle beam B output from the high-frequency cavity 2 is increased. Can be prevented from being reduced.

  In the first embodiment, a specific pulse of the laser light L can be selected by appropriately blocking the laser light L output at a constant interval by the light modulator 14. Furthermore, by using the light modulation unit 14, the timing at which the charged particle beam B is output can be selected with a simple configuration.

  Note that the beam generator 4 may be an electron gun that outputs an electron beam in the form of a beam. For example, the target 11 is a photocathode unit, and the extraction electrode 12 is an anode unit. Then, photoelectrons as charged particles are generated by a photoelectric effect generated by irradiating the target 11 (cathode unit) with the laser light L output from the laser output unit 10. By appropriately selecting the timing of generating the photoelectrons as described above, it is possible to obtain an electron gun capable of suppressing heat generation in the high-frequency cavity 2.

  Note that the beam generator 4 may be an ion source that outputs positive ions in the form of a beam. For example, the target 11 is an ion target portion, and the extraction electrode 12 is a cathode portion. Then, positive ions as charged particles are generated by ablation plasma generated by irradiating the target 11 (ion target unit) with the laser light L output from the laser output unit 10. By appropriately selecting the generation timing of the cations as described above, an ion source capable of suppressing heat generation in the high-frequency cavity 2 can be obtained.

  Next, an operation method of the accelerator 1 according to the first embodiment will be described with reference to FIG. In the description of each step of the flowchart, for example, a portion described as “Step S11” is abbreviated as “S11”.

  First, the frequency setting unit 9 of the high frequency control unit 8 sets a basic frequency based on the selection ratio W input from the ratio setting unit 16 of the output control unit 15 (S11). Next, the high-frequency control unit 8 controls the high-frequency source 3 and inputs the high-frequency K (electromagnetic wave K) of the fundamental frequency to the high-frequency cavity 2 (S12: high-frequency input step).

  Next, the tuning section 17 and the random number output section 19 of the output control section 15 perform tuning timing (period of the fundamental frequency) for causing the laser light L to enter the high-frequency cavity 2 based on the fundamental frequency set by the frequency setting section 9. Is acquired (S13). Next, the tuning unit 17 outputs the tuning signal U to the signal output unit 18 at a timing that matches the tuning timing. Then, the signal output unit 18 to which the tuning signal U has been input outputs the trigger signal G to the laser output unit 10 at the tuning timing (S14).

  Next, the laser output unit 10 that has received the trigger signal G outputs the laser light L at the synchronization timing (S15: laser output step). Next, the selection unit 20 acquires a random number R corresponding to the synchronization timing from the random number output unit 19 (S16). Next, the selection unit 20 controls the light modulation unit 14 based on the obtained random number R, and selects a pulse of the laser light L at a specific timing among the tuning timings corresponding to the cycle of the fundamental frequency (S17: Output control step).

  Next, charged particles are generated by irradiating the target 11 with the laser beam L at a specific timing (S18: particle generation step). Next, the extraction electrode 12 extracts the charged particle beam B by accelerating the charged particles in one direction, and the charged particle beam B is output from the beam generator 4 (S19: beam extraction step). Next, the charged particle beam B passes through the high-frequency cavity 2 (S20: passing step).

(2nd Embodiment)
Next, an accelerator 1A according to a second embodiment will be described with reference to FIGS. Note that the same components as those described in the above-described embodiment are denoted by the same reference numerals, and redundant description will be omitted.

  In the accelerator 1A of the second embodiment, an output high-frequency cavity 21 is provided instead of the extraction electrode 12 of the first embodiment. In the second embodiment, the output high-frequency cavity 21 serves as a beam extraction unit. In the first embodiment, the light modulator 14 selects a pulse of the laser light L. In the second embodiment, the light modulator 14 selects a pulse of the laser light L depending on whether or not the trigger signal G is output.

  As shown in FIG. 4, the output high-frequency cavity 21 is provided at a position close to the target 11. A high frequency source 23 is connected to an end of the output high frequency cavity 21 via an RF input unit 22. Then, the output high-frequency cavity 21 extracts a charged particle beam B by accelerating the charged particles generated in the target 11 in one direction. The charged particle beam B extracted from the output high-frequency cavity 21 enters the main high-frequency cavity 2.

  The output high-frequency cavity 21 is controlled by a control signal N output from the output high-frequency controller 24. Further, the ratio setting unit 16 of the output control unit 15A outputs the frequency information F to the tuning unit 17 and the random number output unit 19, and also outputs the frequency information F to the frequency setting unit 25 of the output high frequency control unit 24. The frequency setting unit 25 sets a fundamental frequency based on the frequency information F. Then, the output high frequency control unit 24 inputs the high frequency K from the high frequency source 23 to the high frequency cavity 2 based on the set fundamental frequency.

  The selection unit 20 of the output control unit 15A according to the second embodiment inputs the selection signal S to the signal output unit 18. The signal output unit 18 outputs the trigger signal G at a specific timing according to the selection signal S output from the selection unit 20. That is, the selection unit 20 selects the output timing of the trigger signal G at irregular intervals. Then, the laser light L is output from the laser output unit 10 at a specific timing among the tuning timings, which are periodic intervals that tune to the cycle of the fundamental frequency.

  As shown in FIG. 5, the period of the fundamental frequency of the high frequency K input from the high frequency source 3 to the high frequency cavity 2 is T1 to T20. Here, the tuning unit 17 of the output control unit 15 </ b> A outputs the tuning signal U to the signal output unit 18 and the selection unit 20 at a timing that matches the periods T <b> 1 to T <b> 20 of the fundamental frequency. The random number R output from the random number output unit 19 is output corresponding to the tuning signal U (the period T1 to T20 of the fundamental frequency). Then, the random number R is input to the selection unit 20.

  Further, the selection unit 20 outputs a selection signal S to the signal output unit 18 according to the tuning signal U and the random number R. For example, when the tuning signal U is input and the random number R corresponding to the tuning signal U is “0”, the selection unit 20 outputs the selection signal S indicating that the trigger signal G is not output to the signal output unit 18. Output to On the other hand, when the random number R corresponding to the tuning signal U is “1”, the selection signal S for outputting the trigger signal G is output to the signal output unit 18. The signal output unit 18 controls the output of the trigger signal G according to the tuning signal U input from the tuning unit 17 and the selection signal S input from the selection unit 20.

  Note that the laser output unit 10 outputs the laser light L according to the trigger signal G output from the signal output unit 18. The laser beam L output from the laser output unit 10 is applied to the target 11 to generate a charged particle beam B, and the charged particle beam B is incident on the high-frequency cavity 2.

  That is, the output timing of the laser beam L, that is, the output timing of the charged particle beam B, is controlled by the random number R of the random number output unit 19. Since the output timing of the laser beam L is determined according to the random number R, the pulse train of the charged particle beam B incident on the high-frequency cavity 2 can be selected at irregular intervals. By doing so, the charged particle beam B is output at irregular intervals, so that the generation of higher-order modes inside the high-frequency cavity 2 can be prevented.

  As described above, in the second embodiment, the presence or absence of the output of the trigger signal G from the signal output unit 18 is controlled based on the random number R output from the random number output unit 19, so that components such as the light modulation unit 14 are not used. Therefore, the timing at which the charged particle beam B is output can be selected with a simple configuration.

  Note that the beam generator 4A of the second embodiment may be an electron gun using the target 11 as a photocathode unit or an ion source using the target 11 as an ion target unit.

  Next, an operation method of the accelerator 1A according to the second embodiment will be described with reference to FIG. First, the frequency setting unit 9 of the high frequency control unit 8 sets a basic frequency based on the selection ratio W input from the ratio setting unit 16 of the output control unit 15A (S21). Next, the high-frequency control unit 8 controls the high-frequency source 3 and inputs the high-frequency K (electromagnetic wave K) of the fundamental frequency to the high-frequency cavity 2 (S22: high-frequency input step).

  Next, the tuning unit 17 and the random number output unit 19 of the output control unit 15A provide a tuning timing (period of the fundamental frequency) for causing the laser light L to enter the high-frequency cavity 2 based on the fundamental frequency set by the frequency setting unit 9. Is acquired (S23). Next, the selection unit 20 acquires the random number R corresponding to the tuning timing from the random number output unit 19 (S24). Then, the selection unit 20 outputs the selection signal S to the signal output unit 18 according to the tuning signal U and the random number R.

  Next, based on the selection signal S input from the selection unit 20, the signal output unit 18 selects a pulse of the trigger signal G at a specific timing among the tuning timings corresponding to the cycle of the fundamental frequency (S25: Output control step). Next, the signal output unit 18 outputs the trigger signal G to the laser output unit 10 at a specific timing (S26). Next, the laser output unit 10 that has received the trigger signal G outputs the laser light L at a specific timing (S27: laser output step).

  Next, charged particles are generated by irradiating the target 11 with the laser beam L at a specific timing (S28: particle generation step). Next, the output high-frequency cavity 21 extracts the charged particle beam B by accelerating the charged particles in one direction, and the charged particle beam B is output from the beam generator 4A (S29: beam extraction step). Next, the charged particle beam B passes through the high-frequency cavity 2 (S30: passing step).

  Although the accelerator according to the present embodiment has been described based on the first embodiment to the second embodiment, the configuration applied in any one of the embodiments may be applied to other embodiments, or each of the embodiments may be applied. May be combined. For example, the extraction electrode 12 of the first embodiment may be applied to the beam generator 4A of the second embodiment, or the output high-frequency cavity 21 of the second embodiment may be applied to the beam generator 4 of the first embodiment. You may.

  In the present embodiment, a linear accelerator is illustrated as an accelerator to which the present invention is applied. However, the present invention may be applied to a circular accelerator such as a cyclotron or a synchrotron. When a charged particle passes through a magnetic field, its trajectory is bent by Lorentz force. A circular accelerator is an accelerator that utilizes this to accelerate charged particles while drawing a circular activation.

  The accelerator 1 (1A) of the present embodiment can be used for a semiconductor manufacturing apparatus (semiconductor manufacturing ion implantation apparatus). For example, the method of manufacturing a semiconductor using the accelerator of the present embodiment includes an irradiation step of irradiating a predetermined substrate (semiconductor) with the charged particle beam B after the passing step of S20 or S30 described above. By irradiating the substrate with the charged particle beam B (ion) having passed through the high-frequency cavity 2, the ion is injected into the substrate. For example, an element such as boron, phosphorus or arsenic is ionized, and the ions are accelerated by an accelerator and injected into a substrate such as silicon, gallium arsenide, silicon carbide or a polysilicon thin film on a glass plate surface. In this way, the electrical characteristics of the semiconductor can be changed. Further, by irradiating ions with an accelerator, ions can be implanted to a deep position in the substrate.

  The accelerator 1 (1A) of the present embodiment can be used in a semiconductor manufacturing apparatus (lithography for semiconductor manufacturing). For example, in the method of manufacturing a semiconductor using the accelerator according to the present embodiment, the charged particle beam B (electrons) is subjected to a predetermined undulator (a magnet row in which N poles and S poles are alternately arranged) after the passing step of S20 or S30 described above. The method includes a light generation step of generating radiation light or free-electron laser oscillation by making the light incident on the semiconductor device, and a lithography step of performing lithography of a semiconductor circuit with the generated light. According to the present embodiment, since a beam with a larger current can be accelerated, high-power light can be generated from the charged particle beam B (electrons) with a large current that has passed through the high-frequency cavity 2. Thus, by performing lithography, a circuit with high throughput can be manufactured. In addition, light generation by the undulator can freely select a wavelength. Therefore, it is possible to perform EUV (Extreme ultraviolet lithography) lithography using shorter wavelength light, for example, extreme ultraviolet light of 13.5 nm, and to manufacture a semiconductor circuit having a finer circuit line width. Become.

  According to the embodiment described above, the output control unit that controls the charged particle beam to be output toward the high-frequency cavity at a specific timing among the timings corresponding to the cycle of the fundamental frequency allows the high-frequency cavity to generate heat. Can be suppressed.

  Although several embodiments of the present invention have been described, these embodiments are provided by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in other various forms, and various omissions, replacements, changes, and combinations can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and equivalents thereof.

1 (1A): accelerator, 2: high-frequency cavity, 3: high-frequency source, 4 (4A): beam generator, 5: main control unit, 6: cavity chamber, 7: RF input unit, 8: high-frequency control unit, 9 ... Frequency setting unit, 10 laser output unit, 11 target unit, 12 extraction electrode, 13 DC power supply, 14 optical modulation unit, 15 (15A) output control unit, 16 ratio setting unit, 17 tuning Unit, 18 signal output unit, 19 random number output unit, 20 selection unit, 21 high-frequency cavity for output, 22 RF input unit, 23 high-frequency source, 24 high-frequency control unit for output, 25 frequency setting unit .

Claims (13)

A high-frequency cavity through which the charged particle beam can pass;
A high-frequency source that inputs an electromagnetic wave of a fundamental frequency into the high-frequency cavity,
A laser output unit that outputs laser light,
A target portion that generates charged particles by being irradiated with the laser light,
A beam extraction unit that extracts a charged particle beam by accelerating the charged particles in one direction,
A random number output unit that outputs a random number corresponding to the cycle of the fundamental frequency,
An output control unit that performs control to output the charged particle beam toward the high-frequency cavity at the specific timing of the timing corresponding to the cycle of the fundamental frequency,
Equipped with a,
The accelerator , wherein the output control unit selects the timing based on the random number output from the random number output unit .   2. The accelerator according to claim 1, wherein the output control unit selects the timing at a constant interval synchronized with a cycle of the fundamental frequency at an irregular interval. 3.   The accelerator according to claim 1, wherein the output control unit changes an interval between the timing at which one charged particle beam is output and the timing at which the next charged particle beam is output.   The accelerator according to claim 1, further comprising: a frequency setting unit configured to increase the basic frequency according to a rate at which the timing is selected within a predetermined period. A signal output unit that outputs a trigger signal that triggers the laser output unit to output the laser light,
A tuning unit that tunes the output timing of the trigger signal to a cycle of a constant interval of the fundamental frequency,
A selection unit for selecting the laser light output from the laser output unit at irregular intervals,
The accelerator according to claim 1, comprising: The accelerator according to claim 5 , further comprising a light modulation unit provided between the laser output unit and the target unit and capable of blocking the laser light. A signal output unit that outputs a trigger signal that triggers the laser output unit to output the laser light,
A tuning unit that tunes the output timing of the trigger signal to a cycle of a constant interval of the fundamental frequency,
A selection unit that selects the output timing of the trigger signal at irregular intervals,
The accelerator according to claim 1, comprising:   The accelerator according to claim 1, wherein the beam extraction unit is an electrode that forms an electric field that accelerates the charged particles in one direction.   The accelerator according to claim 1, wherein the beam extraction unit is an output high-frequency cavity that forms an electric field that accelerates the charged particles in one direction.   The accelerator according to claim 1, wherein the target portion is a cathode portion, and electrons as the charged particles are generated by a photoelectric effect generated by irradiating the cathode portion with the laser light.   The accelerator according to claim 1, wherein the target unit is an ion target unit, and ions as the charged particles are generated by ablation plasma generated by irradiating the ion target unit with the laser light. A high-frequency input step of inputting an electromagnetic wave having a fundamental frequency from a high-frequency source into a high-frequency cavity;
A laser output step of outputting laser light from a laser output unit,
Particle generation step of generating charged particles by irradiating the laser light to the target portion,
Beam extraction step of extracting a charged particle beam by accelerating the charged particles in one direction,
Obtaining the random number from a random number output unit that outputs a random number corresponding to the cycle of the fundamental frequency;
An output control step of performing control to output the charged particle beam toward the high-frequency cavity at the specific timing of the timing corresponding to the cycle of the fundamental frequency,
Passing the charged particle beam through the high-frequency cavity;
Only including,
The operation method of an accelerator, wherein the output control step selects the timing based on the random number obtained from the random number output unit . A high-frequency input step of inputting an electromagnetic wave having a fundamental frequency from a high-frequency source into a high-frequency cavity;
A laser output step of outputting laser light from a laser output unit,
Particle generation step of generating charged particles by irradiating the laser light to the target portion,
Beam extraction step of extracting a charged particle beam by accelerating the charged particles in one direction,
Obtaining the random number from a random number output unit that outputs a random number corresponding to the cycle of the fundamental frequency;
An output control step of performing control to output the charged particle beam toward the high-frequency cavity at the specific timing of the timing corresponding to the cycle of the fundamental frequency,
Passing the charged particle beam through the high-frequency cavity;
A light generating step of generating light by causing the charged particle beam that has passed through the high-frequency cavity to be incident on an undulator,
A lithography step of performing lithography of an electronic circuit using the generated light;
Only including,
The method of manufacturing a semiconductor using an accelerator, wherein the output control step selects the timing based on the random number obtained from the random number output unit .

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