JPH0668993A - Emitted light generator - Google Patents

Abstract

PURPOSE:To reduce the amounts of positive charged ions and dusts trapped in the trajectory of an electron beam so as to prevent reduction of the beam current by disposing an electrode in a beam duct out side the trajectory of the electron beam, and applying a positive potential to the electrode. CONSTITUTION:Light 8 is emitted in the radial direction of the trajectory of an electron beam 20 inside a beam duct 6. A pair of ion removing electrodes 24a and 24b are disposed in the duct 6 existing outside the trajectory of the beam 20, the electrode 24a and 24b exist near the upper wall 6b and lower wall 6c of the duct 6 respectively and positive potential is applied to each of the electrodes by a power supply 25 in the direction perpendicular to the trajectory plane of the electron beam. The produced ions exist in a region 23 adjacent to the side wall 6a of the duct 6. Thus, one component of potential acts as a barrier so that the positive ions and the dust in the region 23 are prevented from moving to the trajectory of the beam 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synchrotron radiation generator, and more particularly, to orbit an electron beam accelerated by an accelerator such as a synchrotron in a beam duct of an electron storage ring. The present invention relates to a radiant light generation device for generating radiated light to the outside of the.

[0002]

2. Description of the Related Art With the demand for higher integration of semiconductor devices, X-ray lithography technology has been studied as one of those for realizing fine processing in the manufacture of VLSI. And in recent years, a powerful X for X-ray lithography
Synchrotron radiation (SOR light) is attracting attention as a radiation source.

The synchrotron radiation light generating device for generating this synchrotron radiation light is required to generate radiation light having a constant intensity as much as possible because it is necessary to match the exposure conditions when exposing the semiconductor. To be done.

A schematic structure of a general synchrotron radiation generator is shown in FIG. In FIG. 3, the electron beam accelerated by the injection electron accelerator 1 is transported by the electron beam transport unit 2, branched by the branch magnet 3, and guided to each electron storage ring 4. The electron beam guided to each electron storage ring 4 is deflected by the deflection magnet 5 and accelerated by the high-frequency accelerating cavity so as to draw a predetermined beam closed trajectory 7 passing near the central trajectory of the ring 11 of the vacuum beam duct 6. Controlled. As a result of the orbital motion of the electron beam, SO
The R light 8 is emitted. The SOR light 8 is extracted from the electron storage ring 4 through the beam line 9. The beam line 9 has a synchrotron radiation monitor 10 for detecting the intensity of the SOR light 8.
Is provided. The intensity of the electron beam in the electron storage ring 4 is detected by the beam current monitor 13. Reference numeral 14 is a control unit, which controls the injection electron accelerator 1 and the branching magnet 3 based on the detection results of the synchrotron radiation monitor 10 and the beam current monitor 11.

In the synchrotron radiation generator, the electron beam current of the accumulated electron beam decreases due to the scattering by the residual gas. For this reason, it is necessary to suppress the scattering of the electron beam due to the residual gas, and it is necessary to make the pressure in the radiation light generator extremely low. Usually, the inside of the beam duct of the synchrotron radiation generator is set to an ultrahigh vacuum by increasing the exhaust speed of the exhaust pump.

FIG. 4A shows a cross section of the beam duct 6 of the conventional synchrotron radiation light generator. The electron beam 2 is stored in the beam duct 6 which is normally at zero potential. The radiated light 8 is radiated toward the outer periphery of the synchrotron ring 11 in the vicinity of the deflection portion of the radiated light generator that deflects the electron beam.

Ions 2 generated inside the beam duct 6
The 1 or positively charged dust or the like is captured by the negative potential of the electron beam 20, and a phenomenon called ion trapping or dust trapping occurs. Therefore, even if the inside of the beam duct 6 is set to an ultrahigh vacuum, the density of impurity particles in the electron beam is
Equivalently increases with captures such as 1.

As described above, even if the inside of the beam duct 6 is made to have an ultrahigh vacuum, the electron beam 20 is generated by the dust generated from the inner wall of the beam duct 6 and the ions 21 trapped in the electron beam by the ion trapping. Scattered and collided, the electron beam current gradually decreases.

Conventionally, in order to suppress such a decrease in electron beam current, as shown in FIG. 4A, an ion removing electrode 22 is arranged in a part of the beam duct 6 and the electrode 6 is removed. The trapped ions 5 were removed by applying a negative voltage to. In this case, the distribution V (y) of the potential V in the y direction is shown in FIG. 4 (b), and the distribution V (x) in the x direction is shown in FIG. 4 (c). In FIGS. 4B and 4C, symbols a, b, and c are potentials of the electron beam 20, respectively.
The potential due to the ion removal electrode 22 and the potential V obtained by combining these are shown.

As a process of generating these positive ions 5, when the electron beam collides with the wall of the beam duct 6 and the residual gas is desorbed, the residual gas is irradiated with radiant light 8 and the residual gas is exposed to light. In the case of stimulated desorption, when the electrons generated by the photostimulated desorption collide with the residual gas and the residual gas is subjected to the electron impact desorption, the adsorbed gas adsorbed on the wall of the beam duct 6 is irradiated with radiant light and ions are emitted. It may be generated. And the ions produced in these processes are initially
It exists in a region 23 near the side wall 6a of the beam duct 6.

[0011]

When such an ion removing electrode 22 is arranged, the distribution of the potential V as shown in FIGS. 4B and 4C is formed, so that the region 23 is initially formed in the region 23. The existing ions 21 can be easily converted into the region 23.
To the orbit of the electron beam 20. Then, it is finally trapped in the potential of the electron beam 20. As a result, the ions 21 remain in the orbit of the electron beam 20, and the ions 21 of the residual gas remain in the orbit of the electron beam 20 depending on the generation frequency of the ions 21 and the removal rate of the ions 21. Further, the positively charged dust near the region 23 is also trapped by the electron beam 20. Therefore, there is a problem that the electron beam current of the electron beam 20 is reduced and the life of the electron beam is shortened.

Therefore, an object of the present invention is to solve the above problems of the prior art and prevent the electron beam current from decreasing due to scattering and collision of the electron beam by the ions trapped in the orbit of the electron beam. An object of the present invention is to provide a radiant light generation device that can prolong the life of an electron beam.

[0013]

In order to achieve the above object, the synchrotron radiation generating apparatus according to the present invention is designed so that an electron beam circulates in a beam duct of an electron storage ring so that the electron beam is out of the orbit of the electron beam. In a synchrotron radiation generator that generates synchrotron radiation toward one side, an electrode is arranged at a position inside the beam duct outside the trajectory of the electron beam, and a positive voltage can be applied to this electrode. To do.

[0014]

The electrode is arranged at a position in the beam duct outside the electron beam trajectory, and a positive voltage can be applied to this electrode. Therefore, the electrode in the beam duct outside the electron beam trajectory is A positive potential is formed at the position. The positive potential of this electrode acts as a barrier against the ions generated near the side wall in the ion beam duct by irradiation of synchrotron radiation, photostimulated desorption, or electron impact desorption. Even for a positively charged duct existing near the side wall in the ion beam duct, the positive potential of this electrode serves as a barrier. As a result, the amount of ions trapped in the trajectory of the electron beam and the amount of positively charged dust can be reduced.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows an embodiment of a synchrotron radiation generator according to the present invention.
The description will be made with reference to FIG. The schematic configuration of the emitted light generator of this embodiment is the same as that shown in FIG.

FIG. 1 shows a cross section of the inside of the beam duct 6. Inside the beam duct 6, the orbital plane of the electron beam 20 is formed perpendicularly to the paper surface. The emitted light 8 is emitted in the radial direction of the trajectory of the electron beam 20. Electron beam 20
A pair of ion removing electrodes 24a and 24b are disposed inside the beam duct 6 outside the orbit of FIG. The ion removing electrodes 24a and 24b are respectively the upper wall 6 of the beam duct 6.
b, near the lower wall 6c and having a plane parallel to these walls. A power source 25 can apply a positive voltage to the ion removing electrodes 24a and 24b in a direction perpendicular to the orbital plane of the electron beam.

FIG. 2 shows the potential V in the beam duct 6.
Indicates. FIG. 2A shows a distribution V (x) of the potential by the electron beam 20 in the x direction. In FIG. 2B, “a” shows the distribution V (x) of the potential by the ion removing electrode 24a in the x direction, and “b” shows the distribution V (x) of the potential by the ion removing electrode 24b in the x direction. Figure 2
(C) is y of the total potential V in the beam duct 6.
The distribution V (y) in the direction is shown, where a is a component due to the electron beam and b is a component due to the ion removing electrodes 24a and 24b. As shown in FIG. 2C, the component b of the ion removal electrodes 24a and 24b of the potential V is outside the component a of the electron beam and inside the region 24 near the side wall 6a. .

Next, the operation of this embodiment will be described. When the electron beam collides with the wall of the beam duct 6 and the residual gas is desorbed, when the residual gas is irradiated with the radiant light 8 and the residual gas is photostimulated and desorbed, the electrons generated by the photostimulated desorption are residual gas. In the case where the residual gas collides with and the residual gas is desorbed by electron impact, and when the adsorbed gas adsorbed on the wall of the beam duct 6 is irradiated with radiant light to generate ions, the generated ions are generated in the beam duct 6. It exists in the region 23 near the side wall 6a. The component b of the potential V serves as a barrier, and the positively charged ions and dust in the region 23 are prevented from moving to the orbit of the electron beam 20.

According to the configuration of this embodiment, the electron beam 20
Since a pair of ion removing electrodes 24a and 24b are provided inside the beam duct 6 outside the orbit of and the positive voltage is applied, a positive potential is formed outside the orbit of the electron beam 20. This potential prevents positively charged ions and dust in the region 23 from moving to the orbit of the electron beam 20. As a result, the electron beam 2
The amount of positively charged ions and dust trapped in the orbits of 0 is reduced, and it is possible to prevent the electron beam current from being reduced due to scattering and collision of the electron beam.

In this embodiment, the pair of electrodes 24a and 24b are arranged as the ion removing electrodes, but the present invention is not limited to this, and one electrode or three or more electrodes may be used. Good.

When a plurality of ion removing electrodes are arranged, it does not matter whether or not these electrodes are arranged so as to face each other.

Further, in the present embodiment, the ion removing electrodes are arranged parallel to the upper wall 6b and the lower wall 6c of the beam duct 6, but
It does not have to be parallel.

[0023]

As described above, according to the present invention,
Since an electrode is placed at a position inside the beam duct outside the electron beam trajectory and a positive voltage can be applied to this electrode, it is possible to form a positive potential outside the electron beam trajectory. It is possible to prevent positively charged ions and dust outside the electrode from moving to the orbit of the electron beam. As a result, the amount of positively charged ions and dust trapped in the orbit of the electron beam is reduced, and the electron beam current can be prevented from being reduced due to scattering and collision of the electron beam. The life of the electron beam can be extended.

[Brief description of drawings]

FIG. 1 is a sectional view of the inside of a beam duct of an embodiment of a synchrotron radiation generator according to the present invention.

FIG. 2 is a diagram showing a potential inside the beam duct. (A) is a distribution V (x) of the potential by the electron beam in the x direction, (b) is the ion removal electrodes 24a, 2
4b potential distribution in the x direction V (x),
(C) is y of the total potential V in the beam duct 6.
The distribution V (y) in the direction is shown.

FIG. 3 is a diagram showing a schematic configuration of a synchrotron radiation generator.

FIG. 4 is a sectional view ((a)) of the inside of a beam duct of a conventional synchrotron radiation generator, and diagrams ((b), (c)) showing potentials inside the beam duct.

[Explanation of symbols]

 1 Electron Accelerator for Injection 2 Electron Beam Transport Section 3 Magnet for Branching 4 Electron Storage Ring 5 Deflection Magnet 6 Beam Duct 7 Beam Closed Orbit 8 Synchrotron Radiation 9 Beamline 10 Synchrotron Radiation Monitor 11 Ring 12 High Frequency Acceleration Cavity 13 Beam Current Monitor 14 Control Part 20 Electron beam 21 Ions 23 Region 24a Ion removal electrode 24b Ion removal electrode

Claims (1)

[Claims] 1. A synchrotron radiation device that circulates an electron beam in a beam duct of an electron storage ring to generate synchrotron radiation outside the orbit of the electron beam. An radiant light generation device characterized in that an electrode is arranged at a position within the beam duct and a positive voltage can be applied to this electrode.