JPH04344500A - Device for taking out radiated beam - Google Patents

Abstract

PURPOSE:To eliminate unequal of radiated beam intensity and of the quantity of radiation due to the enlargement of radiation of synchrotron radiation beams and to enable cutting of short wavelengths which may cause emission of secondary electrons, etc., to be conducted. CONSTITUTION:To oscillate a planar radiation-reflecting mirror 1, the orbit control of a beam of a closed local bump orbit is performed so that the position of a radiation emitting point X is shifted from its initial position by an amount corresponding to the angle theta of oscillation of the mirror 1 when seen from the mirror 1. To oscillate a mirror 10 having a toroidal reflecting interface, the position of the radiation emitting point is shifted, when seen from the mirror 10, from its initial position with respect to the angle theta of oscillation of the mirror 10 by an angle beta in the range of 0<beta<0.8. theta.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention aims to uniformize the intensity of the synchrotron radiation on the exposed surface when the irradiation area of the synchrotron radiation taken out in a flat state is expanded by swinging a synchrotron radiation reflecting mirror. The present invention relates to a synchrotron radiation extraction device for uniformizing the irradiation amount.

0002

2. Description of the Related Art In recent years, synchrotron radiation has been expected to be used as a lithography light source and a medical X-ray fluoroscopy light source in place of ultraviolet rays. This is because synchrotron radiation has a continuous spectrum and contains powerful and highly directional soft X-rays, and these soft X-rays are not suitable for X-rays in lithography technology in terms of throughput and resolution. This is because it is ideal as an X-ray source for medical fluoroscopy.

This synchrotron radiation is emitted when electrons orbiting at a speed close to the speed of light in an ultra-high vacuum synchrotron radiation ring are deflected by a deflection magnet. Since the light is emitted in a horizontally flat state, it has been necessary to expand the vertical irradiation field in lithography techniques that require large-area irradiation.

In order to meet the above requirements, there is a mirror swinging method in which a synchrotron radiation reflecting mirror 1 is placed in the middle of the optical path as shown in FIG. As shown in 18, the synchrotron radiation ring 2
A perturbator 8 (oscillating magnet) for beam oscillation is placed in the 0, and the beam orbit is oscillated on the designed orbit, and the synchrotron radiation emitted from each deflection magnet is oscillated in one direction, such as the vertical direction. There is a rocking method.

[0005]

[Problems to be Solved by the Invention] The former mirror swinging method utilizes reflection of synchrotron radiation midway through the extraction optical path, so it requires a relatively simple structure; Although it has many advantages, such as being able to reduce the duct diameter of the beam line and cutting short wavelengths outside of the soft X-rays of synchrotron radiation, the angle of incidence of the X-rays on the mirror changes depending on the mirror's swing angle. , there are problems such as changes in X-ray reflectance. At this time, since the relationship between the incident angle and the reflectance differs depending on the wavelength of the X-ray, changes in the reflectance not only cause a difference in the intensity of the X-ray, but also
The spectrum of the line becomes different depending on the swing angle. Further, when a condensing mirror is used as a mirror that swings to increase the X-ray intensity, a problem arises in that the amount of X-ray irradiation on the exposure surface becomes non-uniform.

On the other hand, although the latter beam swing method does not have the above-mentioned problems such as swing angle dependence of X-ray reflectance and non-uniformity of exposure intensity, it is not possible to cut the short wavelength of the synchrotron radiation, so it is not suitable for lithography. There are problems such as the generation of secondary electrons that have an adverse effect on There are also drawbacks such as the difference in

The present invention was devised in view of the above-mentioned problems of the prior art, and it is possible to make the X-ray irradiation pattern of each deflection section the same, thereby eliminating the above-mentioned drawbacks associated with the expansion and condensation of the X-ray irradiation field. The aim is to prevent this.

[0008]

[Means for Solving the Problems] Therefore, the synchrotron radiation extracting device of the present invention includes the synchrotron radiation ring and the synchrotron radiation extractor which is swingably provided in the optical path of the synchrotron radiation extracted from the ring. A plurality of steering magnets are provided before and after the deflection magnet in the synchrotron radiation ring to create a local bump trajectory closed around the deflection magnet. The basic feature is that the bump trajectory control of the beam is performed to change the light emitting point position and light emitting angle of the synchrotron radiation according to the swing angle of the synchrotron radiation reflecting mirror.

In the case where the synchrotron radiation reflection mirror, which is the prerequisite configuration in the above configuration, is a plane mirror, as shown in FIG.
The trajectory of the beam on the local bump trajectory is controlled so that the synchrotron radiation point X is shifted by an angle Δθ from its original position when viewed from above.

According to such a configuration, even when the synchrotron radiation reflection mirror 1 is oscillating, the angle of incidence of the synchrotron radiation onto the mirror 1 is always a constant value of θ0, and the mirror reflection of the synchrotron radiation The problem of the dependence of the rate on the angle of incidence is eliminated.

On the other hand, since synchrotron radiation diverges in both the horizontal and vertical directions, it is possible to suppress this spread,
When a concave toroidal mirror is used to increase the exposure intensity in a parallel or condensed state, the situation will be as follows. In the case of a toroidal mirror, light is focused in both the horizontal and vertical directions, but since it is the horizontal light focusing that is dominant in increasing the exposure intensity, the degree of light focusing in the horizontal direction will be described below. First, if the position of the synchrotron radiation emitting point Change. Assuming that the radius of curvature (in the horizontal direction) of such a reflecting mirror is R, as shown in FIG.
sin(θ0)], the rays reflected by the mirror surface become parallel rays. Furthermore, as shown in FIG. 4, if the position of the light source x is moved further away from the position of the focal length f, the reflected light becomes more condensed, and conversely, the light source x is moved closer to the mirror surface than the focal length f. For example, reflected light becomes more spread out than parallel light. If we replace the above light convergence and divergence phenomena with the case where the synchrotron radiation reflecting mirror 10 oscillates as shown in FIGS. 5 and 6 and the position of the synchrotron radiation emission point X does not change, If the center of oscillation W of the synchrotron radiation reflecting mirror 10 with the radius of curvature R is near the mirror reflection point M of the synchrotron radiation, and if the oscillation angle of the mirror is Δθ, then the angle of incidence on the mirror is is θ0−Δθ
becomes. If the focal length at this time is f', then f'=R/2sin
(θ0−Δθ), and f'>f. Therefore, when D=f, D<f', so the beam has a slightly expanded shape and the condensing rate decreases. When the mirror is oscillated in the opposite direction (when Δθ is negative), on the contrary, f'<f, so that the light collection efficiency increases. Also, of course, the width of the beam differs when the condensing rate is high and low, but
Its shape also changes as shown in FIG. On the other hand, the reflectance of a mirror increases as the angle of incidence decreases. Therefore, when Δθ is positive, the light collection rate is small and the reflectance is large. Conversely, when Δθ is negative, the light collection rate is high and the reflectance is low. In this way, the integrated dose distribution when a certain exposure area is exposed by swinging the mirror is determined by the balance of three points: the change in condensing rate due to the change in Δθ, the change in reflectance, and the change in beam shape. When only the mirror rocking method in which the light source point does not move at all is used, when examining the horizontal integrated dose distribution in any part of the exposure area, as shown in Fig. 7, it is large in the center and large in both ends. shows a distribution that decreases with . Therefore,
The cumulative dose distribution in the horizontal direction is not uniform.

On the other hand, when the radiation reflection mirror 10 having such a toroidal mirror surface is oscillated, the oscillation angle Δθ
When the beam trajectory is controlled in the local bump trajectory so that the position of the synchrotron radiation point X is shifted by the swing angle when viewed from the mirror 10 as The degree of horizontal condensation of synchrotron radiation light will be made uniform. However, when we examine the horizontal distribution of the cumulative dose obtained in this case, as shown in FIG. 9, it is large at both ends and small at the center. In this case, there is no change in the condensing rate or change in the beam shape due to the change in the swing angle, but
The cumulative dose distribution in the horizontal direction is still not uniform.

In order to prevent such non-uniformity of the integrated radiation dose distribution in the horizontal direction in any part of the synchrotron radiation irradiation area, when the synchrotron radiation reflecting mirror 10 swings, the synchrotron radiation emission point
It is necessary to shift the position of the mirror, but the amount of shift must be smaller than the amount equivalent to the mirror swing angle. In an experiment to be described later, the present inventors found that the swing angle Δ of the mirror 10 was
By what angle β should the position of the synchrotron radiation emission point X be shifted from the original position when viewed from the mirror with respect to θ, in order to achieve a more uniform cumulative irradiance distribution in the horizontal direction on the irradiation surface? (Actually, when the maximum value of the cumulative dose distribution in the horizontal direction is taken as 100%, we calculated the range of angle β where the difference from the minimum value is less than 7%), as shown in the following formula. The results were as follows. 0<β<0.8・Δθ

Therefore, when the above-mentioned emitted light reflecting mirror 10 is a concave toroidal mirror, the mirror 10 has an angle Δ
The trajectory of the beam on the local bump trajectory is controlled so that when the mirror 10 is tilted, the synchrotron radiation point X is shifted from its original position by an angle β expressed by the above equation.

[0015]

[Examples] Specific examples of the present invention will be described below.

FIG. 10 is a plan view showing the outline of the configuration of an embodiment of the device of the present invention, and 2 is an electron storage ring,
The electron beam orbiting in the ring 2 is deflected by a deflection magnet 3.
When deflected, synchrotron radiation is emitted in the tangential direction of the orbit. This synchrotron radiation is taken out of the ring 2 by beam lines 4a and 4b, is swung vertically by the reflection and swinging of synchrotron radiation reflection mirrors provided in mirror chambers 5a and 5b, and is swung horizontally. The irradiation field of the flat radiation light is expanded.

In this embodiment, as shown in FIGS. 10 and 11, two steering magnets 6a to 6d are provided on orbits in front and behind the deflection magnet 3, and the supply to these magnets is By adjusting the current, it is possible to create a closed local bump trajectory of the electron beam centered on the deflection magnet 3, as shown in FIG. 11 (this local bump trajectory changes only within each deflection section). (Therefore, it does not affect other deflection parts). Moreover, the steering magnet 6a
To adjust the current supplied to the mirrors 6d to 6d, as shown in FIG. In the case of the synchrotron radiation position, the optimum emission point and emission angle of the synchrotron radiation light (as described later, it differs depending on the type of synchrotron radiation reflection mirror) are calculated, and the emission point and emission angle of such synchrotron radiation light are set. The local bump trajectory centered on the deflection magnet 3 that can be used is determined, and each supply current to the steering magnets 6a to 6d necessary for forming the trajectory is determined.Based on the determination, the control circuit 7a to the amplifier circuit This is carried out by outputting a current supply control signal to the current supply devices 70a to 70d of each of the steering magnets 6a to 6d via the magnets 7b.

The beam trajectory control of the local bump trajectory actually performed by the control circuit 7a, the amplifier circuit 7b, and the current supply devices 70a to 70d is controlled differently depending on the type of the emitted light reflecting mirror.

That is, when the radiation reflection mirrors provided in the mirror chambers 5a and 5b are flat mirrors, as shown in FIG. The trajectory of the beam was controlled so that the light emitting point X was shifted by an angle Δθ from its original position. As a result, the angle of incidence of the emitted light on the mirror 1 is θ0
is always constant, and its reflectance no longer changes. Therefore, the problem that the spectrum of the irradiated X-rays changes as the swing angle changes does not occur at all. Note that due to this reflection, the vertical irradiation field of the synchrotron radiation is expanded by an angle Δθ.

On the other hand, when the mirrors in the mirror chambers 5a and 5b are toroidal mirrors, if the same control as for the above-mentioned plane mirrors is performed, the cumulative irradiation amount will be larger than when plane mirrors are used. When taking the cumulative dose distribution in the horizontal direction at any part of the irradiation surface, it is large at both ends and small at the center, making it non-uniform. On the other hand, if the synchrotron radiation point position and angle do not change even if the synchrotron radiation reflection mirror oscillates, the beam shape and degree of convergence will change significantly as the synchrotron radiation is swung in the vertical direction, so Although the distribution is different from that in the case of , it is still non-uniform. Therefore, the following experiment was conducted to determine within what range the movement of the synchrotron radiation point I was asked.

First, the electron beam energy E measured in the electron storage ring 2 used in this experiment is 1 GeV,
Beam current I is 200mA, deflection magnet magnetic flux density B
was 1.2T. In addition, the total length from the light emitting point X formed by beam lines 4a and 4b to the irradiation surface is 8 m, and as shown in
As shown in FIGS. 3(a) and 3(b), mirror chambers 5a and 5b are provided 2.7 m from the synchrotron radiation point
A radiation reflecting mirror 10 having a toroidal reflecting surface with a length of 3 m and a vertical radius of curvature of 257 m is provided (the horizontal light collection rate of this mirror 10 is 8 m/2.7 m = approximately 2.96). The synchrotron radiation reflecting mirror 10 is tilted at an angle θ0 of 21 mrad with respect to the optical path of the synchrotron radiation in the neutral state, and is installed so that it can swing vertically within a range of ±6 mrad from the neutral state when swinging. .

At this time, the swing angle Δ of the emitted light reflecting mirror 10
When the position of the synchrotron radiation emission point . At this time, in order to maximize the uniformity of the irradiation amount in the vertical direction, the mirror should be oscillated at a constant angular velocity, so the oscillation angular velocity was kept constant. Figure 14 shows the case where the synchrotron radiation point X is not moved at all, and the area below the center has the highest irradiation amount, and when this is taken as 100%,
The irradiation amount decreased toward both ends and upward, and the maximum value of the difference in irradiation amount was about 7%. On the other hand, FIG. 15 shows that the irradiation amount is the highest when irradiation is performed with the position of the synchrotron radiation emission point X shifted by an angle of Δθ/2 when viewed from the mirror 10 with respect to the swing angle Δθ of the mirror 10 If this is set as 100%, the irradiation amount decreases as you move toward the center, and the difference in irradiation amount is approximately 5%.
It became. At this time, although it is not as much as in the case of the plane mirror described above, compared to the case where the synchrotron radiation emission point
Since the change in the incident angle with respect to 0 is also small, the change in the spectrum of the incident X-ray due to the change in the swing angle is also small. However, in this case, in the previous case (constant angular velocity), so that the integral value of the horizontal direction irradiation amount is constant for each arbitrary point in the scanning direction.
Unlike, the scanning speed is adjusted.

Furthermore, the present inventors carried out irradiation by adding various deflections to the swing angle Δθ of the synchrotron radiation reflection mirror 10 and the angle β for shifting the position of the synchrotron radiation emission point X, and investigated the difference in the irradiation amount. When the maximum value was continued, the result was as shown in FIG. 16. The inventors have determined that the range of β is 0<
It was set as β<0.8·Δθ.

[0024]

Effects of the Invention According to the apparatus of the present invention described in detail above, when expanding the irradiation field of horizontally flat synchrotron radiation, the incident angle of the synchrotron radiation reflectance of the synchrotron radiation reflection mirror used while being oscillated can be adjusted. It becomes possible to eliminate the dependence and keep the irradiation intensity constant, and it also becomes possible to cut short wavelength components of synchrotron radiation, which cause the emission of harmful secondary electrons in lithography and the like. Furthermore, it is possible to minimize the non-uniformity of the horizontal irradiation dose distribution, which is a problem especially when the emitted light reflecting mirror is a toroidal mirror.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the basic configuration of the present invention in a case where the emitted light reflecting mirror is a plane mirror.

FIG. 2 is an explanatory diagram showing the degree of horizontal convergence of synchrotron radiation when the radiation light reflecting mirror is a toroidal mirror and the position of the radiation emitting point does not change.

FIG. 3 is an explanatory diagram showing a state of condensing light by a mirror having a toroidal reflective surface.

FIG. 4 is an explanatory diagram showing a state of convergence of light by a mirror having a toroidal reflective surface.

FIG. 5 is an explanatory diagram showing a scanning state of radiation light when a radiation reflection mirror having a toroidal reflecting surface is oscillated in a conventional configuration.

FIG. 6 is an explanatory diagram showing a scanning state of synchrotron radiation according to the conventional configuration.

FIG. 7 is a graph showing the cumulative irradiation amount distribution in the horizontal direction of an arbitrary part of the radiation irradiation surface when the position of the radiation emission point is fixed and the toroidal mirror is oscillated.

[Fig. 8] An explanatory diagram showing the degree of horizontal convergence of synchrotron radiation obtained when the toroidal mirror is oscillated and the position of the synchrotron radiation emission point is also shifted by the same angle at the same time. It is.

FIG. 9 is a graph showing the integrated irradiation dose distribution in the horizontal direction at an arbitrary portion of the radiation irradiation surface when the radiation emission point is controlled to be shifted along with the mirror rocking.

FIG. 10 is a plan view showing an outline of the configuration of an embodiment of the device of the present invention.

FIG. 11 is an explanatory diagram showing a configuration for forming a local bump trajectory in this embodiment.

FIG. 12 is a circuit diagram showing a configuration for supplying current to a steering magnet used to form the local bump trajectory.

FIG. 13 is an explanatory diagram showing a configuration in the case where a toroidal mirror is used as the emitted light reflecting mirror in the configuration of this embodiment.

FIG. 14 is a graph showing the amount of radiation on the irradiation surface when the radiation point is not moved.

FIG. 15 is a graph showing the amount of radiation on the irradiation surface when the radiation point is moved.

FIG. 16 is a graph showing the results of taking the maximum value of the difference in irradiation amount when the amount of movement of the synchrotron radiation point with respect to the rocking angle of the mirror is changed.

FIG. 17 is an explanatory diagram of a mirror rocking method.

FIG. 18 is an explanatory diagram of the beam swing method.

[Explanation of symbols]

1, 10 Synchrotron radiation reflecting mirror 2 Electron storage ring 3 Deflection magnets 4a, 4b Beam lines 5a, 5b Mirror chambers 6a to 6d Steering magnet 7a
Control circuit 7b Amplification circuits 70a to 70d Current supply device 8 Perturbator X Synchrotron radiation point Δθ Mirror swing angle β Shift angle of synchrotron radiation point θ0
Mirror tilt angle in neutral state

Claims (3)

[Claims] Claim 1: A synchrotron radiation ring that emits synchrotron radiation when the beam is deflected by a deflection magnet for beam circulation, and a synchrotron radiation that is taken out from the ring in one direction by its oscillation. Shake it,
In a synchrotron radiation extraction device having a synchrotron radiation reflection mirror for expanding a synchrotron radiation irradiation area in the direction, a plurality of steering magnets are provided before and after the deflection magnet to create a local bump trajectory that is closed around the deflection magnet. In addition, the synchrotron radiation is characterized in that the trajectory of the beam is controlled in the orbit to change the light emitting point position and the light emission angle of the synchrotron radiation according to the swing angle of the synchrotron radiation reflecting mirror. Retrieval device. 2. In the radiation extraction device according to claim 1, when the radiation reflection mirror is a plane mirror,
The local bump trajectory is such that when the mirror is tilted by an angle Δθ from the initial incident angle θ0 of the synchrotron radiation to the mirror around the swing center, the light emitting point is shifted by the angle Δθ from the original position when viewed from the mirror swing center. 2. The synchrotron radiation extraction device according to claim 1, wherein the radiation beam extraction device is configured to control the trajectory of the beam. 3. In the synchrotron radiation extraction device according to claim 1, when the synchrotron radiation reflecting mirror is a concave toroidal mirror, the initial incident angle of the synchrotron radiation to the mirror is θ0 around the center of oscillation of the mirror. The trajectory of the beam in the local bump trajectory is controlled so that when the beam is tilted by an angle Δθ from the center of rotation of the mirror, the synchrotron radiation emission point is shifted from its original position by an angle β expressed by the following formula. The emitted light extraction device according to claim 1, characterized in that: 0<β<0.8・Δθ