JPH0766880B2 - Operating method of small SOR device - Google Patents

Description

The present invention relates to a method for operating an SOR device, and more particularly to a small SOR device.
The present invention relates to an operation method capable of accumulating a large current even in a device.

[Prior Art] In recent years, research has been actively conducted to use SOR light (synchrotron radiation) in various fields. Here, SOR light refers to an electromagnetic wave emitted forward in the tangential direction when an electron circularly moves at the speed of light. At present, there is great expectation to use SOR light as a light source for LSI lithography as one form of using SOR light. A characteristic of SOR light is a soft X that has unprecedented high intensity and good directivity.
It may include a line region. From this, it is considered and expected that it has great potential as a light source for X-ray lithography. When SOR light comes to be used for X-ray lithography, it is expected that a 64Mbit DRAM or a semiconductor device having an integration degree higher than that, which is expected to have great demand, can be easily manufactured.

The SOR light expected to be used in this way can be obtained by the SOR device (synchrotron device). SOR equipment
A linac as an injector for accelerating the electron beam, a synchrotron that orbits the electron beam incident from the linac, and a synchrotron that emits SOR light when the electron beam trajectory is bent. It consists of a device that can be taken out and used. In such a SOR device, an S that is suitable for X-ray lithography
In order to obtain OR light, it is necessary to multiply inject electron beams into the synchrotron, accumulate a large amount of current, and orbit the electron beams with a steady energy of 800 MeV.

[Problems to be Solved by the Invention] By the way, when the above-mentioned SOR device is provided on the market as a light source for X-ray lithography, the size of the SOR device should be reduced to at least a size that can be installed in one room of a factory. desired. However, if the SOR device is configured in such a small size, in the linac, the electron beam cannot be accelerated to the above-mentioned stationary energy of 800 MeV due to the length restriction, and the linac is limited to about 45 MeV. Therefore, as a method of operating such a small SOR device, it is necessary to repeatedly inject an electron beam at 45 MeV into the synchrotron to obtain a predetermined accumulated current, and then accelerate the orbit to a steady energy of 800 MeV and orbit it. . However, when the energy of the electron beam incident on the synchrotron is as low as 45 MeV, the radiative decay effect cannot be expected, and the beam size is large for a while after the incidence, which shortens the life of the electron beam. Even if it enters, it disappears one after another and a large current cannot be stored.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method of operating a SOR device capable of accumulating a large current even with a small SOR device.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides an electron beam incident from a linac into a vacuum chamber of a synchrotron by supplying energy by a high-frequency accelerating cavity and deflecting it by a deflection electromagnet. In the operating method of a small SOR device that keeps orbiting while maintaining a steady energy of 800 MeV, the electron beam is accelerated to 45 MeV by a linac and is injected into the vacuum chamber of the synchrotron, and then the energy of the incident electron beam is 300 MeV. And hold it for a certain period of time, then lower the energy at the time of incidence to 45 MeV,
Inject the electron beam at 45 MeV from the linac again,
And after repeating this process to increase the accumulated current in the vacuum chamber, the energy of the electron beam is changed to a steady energy of 800 MeV.
The normal operation is performed by raising the temperature up to.

[Operation] In the operation method of the present invention, every time an electron beam is injected into the vacuum chamber of the synchrotron at 45 MeV, the energy of the electron beam is increased to 300 MeV and held for a certain period of time, and then the energy at the time of injection is again generated. Since it is returned to 45 MeV, the electron beam incident on the synchrotron can be sufficiently radiatively attenuated by the next injection to reduce the beam size. Therefore, the beam life is dramatically improved, and the amount of accumulated electron beams can be increased rapidly. That is, when the beam energy in the synchrotron is kept constant at 45 MeV and additionally injected, the radiation decay time of the electron beam at the time of incidence is long and the electron beam spreads spatially. However, if the energy is increased to 300 MeV for each incident and held for a certain period of time, the electron beam can be immediately radiatively attenuated to reduce the beam size.

[Embodiment] An embodiment of the present invention will be described below with reference to the accompanying drawings.

Figure 2 shows a small SOR device. In the figure, reference numeral 1 is a linac as an injector for accelerating an electron beam, and a high frequency is injected into an electron generated from an electron generator 2 by an accelerating tube 3 to accelerate the electron. The orbit of the electron beam accelerated by the linac 1 is bent by the bending electromagnets 4 and 5, and is guided to the synchrotron 6.

The synchrotron 6 includes a sealed vacuum chamber 7, deflection electromagnets 8 inserted in the four deflection portions of the chamber 7, and focusing electromagnets inserted in each linear portion between the deflection electromagnets 8 which are adjacent to each other. 9, a high-frequency accelerating cavity 10 which is inserted into one of the straight portions and supplies energy to the electron beam with the applied high-frequency wave, and a vacuum pump which is connected to the vacuum chamber 7 and ensures a high vacuum state inside (not shown). ) And. The orbit of the electron beam incident from the linac 1 into the vacuum chamber 7 is bent by the deflecting electromagnet 8, the beam is focused by the converging electromagnet 9, and energy is supplied by the high-frequency accelerating cavity 10. It will orbit in 7.

In this way, the electron beam converging in the vacuum chamber 7 emits SOR light, and this SOR light is extracted via the beam channel 11 as necessary and guided to the exposure device 12. Then, it is used as a light source for LSI lithography.

In this embodiment, in order to use the SOR light as a lithography light source in this way, the SOR device has a size that can be installed in a room of about 15 m × 15 m. This size is usually determined based on the size of the room where lithography is performed. To specifically show the size of the SOR device, the diameter D of the vacuum chamber 7 is about 7 m, and the length L of the linac 1 is about 10 m. Due to such length restrictions, the energy of the accelerated electron beam is 45 MeV in linac 1.
Limited in extent. However, in order to use SOR light for lithography, it is said that a large current storage of 300 to 500 mA is required.

In the present embodiment, the SOR device is shown below so that a large current can be stored even when only such a low incident energy is obtained and SOR light suitable as an X-ray lithography light source can be emitted for a long time. Is driving like. As shown in Fig. 1, the operation of this SOR device is 45Me by the linac 1.
Every time the electron beam accelerated to V is incident on the synchrotron 6 at a predetermined cycle t (incident timing is indicated by an arrow), the energy of the electron beam is increased to 300 MeV,
Hold for a predetermined time, reduce again to 45 MeV to accumulate a predetermined amount of electron beam (injection operation A), then increase the energy of the electron beam to 800 MeV which is a steady state, and set a predetermined wavelength (4-10 Å) and The SOR light having the light intensity is obtained (acceleration operation B), and then the energy of the electron beam is maintained at 800 MeV so that the predetermined SOR light can be extracted as needed (steady operation C). .

Therefore, according to such an operation, the energy of the electron beam incident on the synchrotron 6 from the linac 1 is
45MeV, 300Me once before the next electron beam injection
Since it is increased to V, the beam size spread spatially at the time of incidence will be contracted by the radiation attenuation effect, and the number of electrons that disappear due to collision with the residual gas in the vacuum can be reduced,
The life of the incident electron beam can be extended.

By increasing the energy of the incident electron beam to 300 MeV and holding it, the intensity of the SOR light emitted when the orbit is bent by the deflection electromagnet 8 and irradiating the inner wall of the vacuum chamber 7 is increased and the wavelength is shortened. It is possible to promote degassing from the vacuum chamber 7 and increase the degree of vacuum in the vacuum chamber 7, that is, when the vacuum chamber 7 is made of stainless steel, C and H are present in the structure and grain boundaries of the chamber 7.
Since such impurities are included, there is a limit to improvement of the degree of vacuum only by exhausting with a vacuum pump. For example, a vacuum chamber 7 made of stainless steel whose moisture is removed by baking
Even if is used, the limit is 10 ^-9 torr when the electron beam goes around. However, when the energy of the electron beam is increased as described above, the SOR light has its light intensity increased in proportion to the fourth power of the energy of the electron beam and irradiates the inner wall of the vacuum chamber 7, and the impurities are It can be taken out in the form of gas and pumped to reach the 10 ^-10 torr level in a short time. Once the impurities are removed in this way, a high vacuum state can always be ensured in later use, and from this point as well, the life of the incident electron beam can be extended.

Further, as described above, the beam size can be reduced, and at the same time, the degree of vacuum in the vacuum chamber 7 can be increased. Therefore, it is clear that the life of the electron beam can be dramatically improved and a large current can be accumulated due to these synergistic effects. Is.

Further, according to the present embodiment, the electron beam increased to 300 MeV as described above is lowered again to 45 MeV and the next electron beam is made incident, so that the electron beam can be stably made to additionally enter the synchrotron 6.

The energy control of the electron beam as described above can be performed by controlling the magnitude of the magnetic field generated by the deflection and focusing electromagnets 8 and 9. Therefore, in the present embodiment, as shown in FIG. 3, the deflection electromagnet 8 and the focusing electromagnet 9 are connected to the control computer 15 via the power supply devices 13 and 14, respectively, and the power supply device is set according to a preset program. By controlling 13 and 14, the magnitude of the magnetic field generated by the electromagnets 8 and 9 is controlled.

FIG. 4 shows an operation flow of the deflection and focusing electromagnets 8 and 9 controlled by the control computer 15. In this control, first, the control computer 15 is initialized (step 100), and then it is determined whether or not the electromagnets 8 and 9 can be excited (step 110). If the result of this determination is YES, the electromagnets 8 and 9 are excited so that they can orbit the electron beam corresponding to the energy at the time of incidence, that is, 45 MeV (step 120). Then, it is determined whether or not the electron beam can be incident on the synchrotron 6 (step 130), and if YES, based on the incident timing pulse (pulse output at the arrow position in FIG. 1) (step 140). The injection operation pattern registered in advance in step 100 is output (step 150). As described above, this injection operation pattern accelerates and holds the electron beam of 45 MeV incident on the synchrotron 6 from the linac 1 up to 300 MeV, and lowers it to 45 MeV again by the next injection. It controls the magnitude of the magnetic field. The output of this injection operation pattern is repeatedly performed until a predetermined pulse of the electron beam is injected and it is determined in step 160 that acceleration is possible, and a predetermined amount of the electron beam is accumulated in the synchrotron 6. When it is determined in step 160 that acceleration is possible (when the determination result is YES), the acceleration operation pattern previously registered in step 100 is output (step 170). As a result, the energy of the electron beam in the synchrotron 6 is gradually increased from 300 MeV to 800 MeV. After that, the electron beam energy is set to 80
Maintaining 0 MeV, the steady operation that can take out a predetermined SOR light at any time is continued (step 180). When this steady operation is performed for a predetermined time and it is determined that the demagnetization is possible (step 190), the operation of the SOR device is stopped (step 200), and then the process returns to step 10 to operate the SOR device. To resume.

Although the injection operation pattern is output every time the electron beam is incident on the synchrotron 6 from the linac 1, the injection operation pattern may be output each time a predetermined pulse of the electron beam is incident.

[Effects of the Invention] In summary, according to the present invention, the following excellent effects are exhibited.

(1) The energy of the electron beam injected at 45 MeV is increased to 300 MeV before the next injection and is held for a certain period of time.
Since it is set back to 45 MeV, even in a small SOR device whose incident energy is as low as 45 MeV, the electron beam can be radiatively attenuated immediately after the incident to reduce the beam size, and the beam life can be greatly extended. A large amount of current can be stored in the device.

(2) Since the intensity of the SOR light that irradiates the inner wall of the vacuum chamber increases, it is possible to promote degassing from the inner wall of the vacuum chamber and improve the degree of vacuum.
A large amount of current can be stored in the device.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a temporal change in beam energy obtained by an operating method according to an embodiment of the present invention, and FIG. 2 is a schematic configuration of an SOR device to which the embodiment is applied. FIG. 3 is a diagram showing the configuration of the control unit of the SOR device to which one embodiment is applied, and FIG. 4 is a flow chart diagram showing the operation of the deflection and focusing electromagnets controlled by the control computer. In the figure, 1 is a linac, 6 is a synchrotron, 7 is a vacuum chamber, 8 is a bending electromagnet, and 10 is a high-frequency acceleration cavity.

Claims (1)

[Claims] 1. A method for operating a small SOR device in which an electron beam incident from a linac into a vacuum chamber of a synchrotron is circulated while being supplied with energy by a high-frequency accelerating cavity and being deflected by a deflection electromagnet while maintaining a constant energy of 800 MeV. In the above, after accelerating the electron beam to 45 MeV by a linac and injecting it into the vacuum chamber of the synchrotron, the energy of the incident electron beam is increased to 300 MeV and held for a certain time, and then the energy at the time of incidence is reduced to 45 MeV Then, the electron beam is again injected from the linac at 45 MeV, and this is repeated to increase the accumulated current in the vacuum chamber, and then the energy of the electron beam is increased to the stationary energy of 800 MeV to orbit and perform stationary operation. A method for operating a small SOR device, which is characterized in that