JPS62136800A - X-ray generator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a compact X-ray generator used for semiconductor lithography, physical property research, and the like.

[Prior art and its problems] When electrons are orbiting at a speed close to the speed of light in an accelerator, if their path is deflected by a magnetic field, synchrotron radiation light (S Or ()) changes from X-rays to infrared rays. It is well known that it is possible to obtain continuous light extending up to Therefore, if these powerful X-rays are used as a light source for VLS I lithography exposure with a line width of 0.5 μm or less, productivity will increase. Because it is emitted, it has the advantage of good directivity and high resolution in area lithography.

However, since the deflection device in the accelerator described above uses a normal conducting magnet, the accelerator becomes large, and its diameter can reach several tens of meters. It was very difficult.

Therefore, we used a superconducting magnet in the deflection device,
It is possible to make the accelerator smaller by making the deflection radius smaller by making the generated magnetic field stronger, but in this case,
There were problems as described below.

Conventionally, from the perspective of downsizing the accelerator, the injector for introducing electrons into the accelerator ring was also downsized. Therefore, the acceleration energy obtained by such an injector is low, and the injected electrons are accelerated within the ring until they reach a predetermined energy. In this type of conventional accelerator, as the energy of the electrons in the ring increases from a low state, the magnetic field generated by the deflection device must also be changed from a small value to a large value, until the electrons reach a predetermined energy. Until this happens, that is, while the deflection magnetic field is relatively small, the superconducting magnet cannot operate in persistent current mode due to its morphology, and it is necessary to supply electricity to the superconducting magnet from an external power source. The drawback was that a large amount of liquid helium, the cooling medium, was consumed due to the intrusion of heat.

[Purpose of the Invention] This invention has been made to eliminate the above-mentioned problems, and by constantly operating the superconducting magnet in persistent current mode, the superconducting magnet is free from Joule heat and heat intrusion from the current leads. An object of the present invention is to provide an X-ray generator that reduces the consumption of liquid helium by eliminating the generation of helium.

[Structure of the Invention] The X-ray generator of the present invention includes an acceleration ring in which electrons circulate, an injection means for injecting the electrons into the acceleration ring, and a plurality of elements for deflecting the direction of the electrons circulating in the acceleration ring. In the X-ray generator comprising a deflection means and a boat section for extracting X-rays emitted from the deflected electrons, the incidence means accelerates the electrons incident on the ring to a predetermined energy. and the deflection means is a superconducting magnet used in persistent current mode.

[Example] In this invention, when electrons are injected into an accelerator by an injector, the injector accelerates the electrons to a predetermined energy, and this predetermined energy is used to control the electrons orbiting in the accelerator with a permanent current. The beam is deflected by a superconducting magnet depending on the mode. Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of an X-ray generator using an accelerator according to the present invention.

1 indicates an acceleration ring configured in a rectangular shape, 2 is a superconducting magnet for deflection provided at the four corners of the acceleration ring 1, and each superconducting magnet 2 causes 3,
The trajectory of the electron beam is deflected by 90° by a central magnetic field of 9 Tesla. Reference numeral 3 denotes a high frequency acceleration cavity for replenishing the energy of electrons attenuated by X-ray radiation, and is provided on the trajectory of the electron beam connecting each superconducting magnet 2 and on the opposing trajectory. Reference numeral 4 denotes an incidence control system provided on the other opposing trajectory, in which an inflector or park beta is used.

5 is a focusing magnet provided so that the electron beam does not diverge;
are provided at the entrance and exit portions of electrons. Reference numeral 6 denotes an acceleration ring N, which is an injector for injecting electrons via one side of the injection control system 4, and this injector 6 accelerates the electron beam to a predetermined energy of 450 MeV.

Reference numeral 7 denotes a boat for extracting X-rays emitted by deflection of the electron beam, and is provided at the exit portion of the electron beam of the superconducting magnet 2. 8 is a power source for supplying current to the superconducting magnet 2 operating in persistent current mode.

Next, the operation of the accelerator having the above configuration will be explained.

In advance, the four superconducting magnets 2 are supplied with current from the power source 8 for a predetermined period of time, enter a persistent current mode, and are excited so that the central magnetic field becomes 3.9 Tesla. The current leads may then be removed.

The electron beam entering the acceleration ring 1 is accelerated to an energy of 450 MeV by the injector 6, which has an energy matching the magnetic field generated by the persistent current mode superconducting magnet 2, and is then accelerated by the injector 6 to an energy of 450 MeV. and enters the acceleration ring l.

The incident electron beam orbits within the acceleration ring l with the acceleration energy, and when passing through the superconducting magnet 2, the electron beam is deflected, and at this time, X-rays are emitted in the tangential direction of the trajectory of the electron beam. is taken out via boat 7. By emitting X-rays in this way, the reduced acceleration energy of the electrons is transferred to the high-frequency acceleration cavity 3.
It is now replenished by

In the embodiment described above, the amount of liquid helium consumed by the four superconducting magnets 2 was approximately 100Q until the injection of the electron beam by the injector 6 was completed.

Next, for comparison, we measured the amount of liquid helium required in the case of a device in which an electron beam is made to enter from the injector 6 with low acceleration energy and the electron beam is accelerated in the acceleration ring 1.

In this case, the superconducting magnet 2 is set so that a generated magnetic field of 22 Tesla can be obtained in normal conduction. Then, the electron beam injected by the injector 2 with a low level of energy is accelerated in the acceleration ring 1 to 450 Me■, which is the same as the acceleration energy in the previous example, and in parallel with this acceleration operation, the electron beam is The magnetic field generated by magnet 2 was increased to 39 Tesla, and then the persistent current mode was set. In this example,
The superconducting magnet 2 must operate under normal conductivity until it is accelerated to a predetermined energy in the acceleration ring 1, and the amount of liquid helium consumed during this period is approximately 316
Q, and approximately three times as much liquid helium is consumed as compared to the above embodiment.

As explained above, according to this embodiment, by increasing the incident energy of the electron beam, the magnetic field of the superconducting magnet 2 as a deflection device can also be set large from the point of incidence of the electron beam, and as a result, the superconducting magnet Since it is always operated in persistent current mode, there is no generation of Joule heat and the consumption of liquid helium can be significantly reduced. In addition, when superconducting magnets 2 are used in normal conduction as in the comparative example, the power supply must be prepared for the same number of superconducting magnets 2, but as in this embodiment, they are always used in persistent current mode. As a result, even if there are four superconducting magnets 2, one common power supply device can be used to supply them, and the system can be made inexpensive.

Furthermore, when the amount of electron beams orbiting in the acceleration ring l decreases and the amount of X-ray radiation decreases, in the comparative example, after lowering the magnetic field, that is, the superconducting magnet 2 is changed from the persistent current mode to the normal mode. After switching to conductive operation, it is necessary to inject an electron beam from the injector 6, which is a complicated process and also results in wasted liquid helium. In this case, the electron beam can be incident from the injector 6 while the magnetic field generated by the superconducting magnet 2 remains unchanged, and liquid helium is not consumed during this time.

In this embodiment, a linear accelerator is used as the injector 6, but an injector 6 using a zinc oxide or a microtron may also be used. Further, the high frequency acceleration cavity 3 may be of the order of two units, and the number of boats 7 may be further increased as necessary.

[Effects of the Invention] As explained above, in this invention, the superconducting magnet used as the deflection means used in the accelerator ring is always operated in persistent current mode, which prevents generation of Joule heat and intrusion from the current lead. Heat can be eliminated and the consumption of liquid helium for cooling superconducting magnets can be significantly reduced.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of an X-ray generator according to the present invention. l...Acceleration ring, 2...Superconducting magnet, 3.
...High-frequency acceleration cavity, 4.Injection control system, 5.Focusing magnet, 6.Injector, 7.Boat, and...Power source.

Claims (1)

[Claims] (1) An acceleration ring in which electrons orbit, an injection means for injecting electrons into the acceleration ring, a plurality of deflection means for deflecting the electrons orbiting inside the acceleration ring, and radiation from the deflected electrons. In the X-ray generator, the injection means accelerates the electrons incident on the ring to a predetermined energy, and the deflection means is in a persistent current mode. An X-ray generator characterized in that a superconducting magnet is used.