JPH09148092A - X-ray generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an X-ray generator capable of being stably used for a long time by controlling scattering particles to be generated with X-ray from plasma by a control member and a stopping member, and increasing the relative pressure of gas along the X-ray advancing direction. SOLUTION: In a depressurized vacuum container 420, a target member 403 of Ta is irradiated by YAG laser beam 409 and excited, and X-ray and scattering particles are generated from plasma 411. The X-ray is taken from an optical element 410 and guided to an X-ray optical system. The scattering particles are stopped by controlling the directional distribution of the discharge by a scattering particle control member 401 provided adjacent to or near the target member 403 and by supplying gas having the high transmission factor of X-ray such of He. A scattering particle stopping member composed of a duct 412 provided with baffles 404 to 407 provided with openings facing the optical element 410 is arranged, and He gas is supplied from a gas introducing pipe 413. Therefore, pressure outside the duct 412 is relatively decreased lower than the pressure on the optical element side, and sticking of the scattering particles is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray generator suitable for use in an X-ray apparatus such as an X-ray microscope, an X-ray analyzer and an X-ray exposure apparatus.

[0002]

2. Description of the Related Art When a laser beam (an example of an excitation energy beam) is condensed and irradiated on a target member placed in a vacuum vessel having a reduced pressure, the target member is rapidly turned into plasma, and the plasma emits very bright light. It is known that high X-rays are radiated (emitted) (generate X-rays).

Along with the generation of X-rays, high-velocity particles such as electrons and ions are emitted from the plasma, and particles are emitted from the target member (eg, gasified material, ionized material, material pieces, etc.). Are emitted and scattered in the vacuum container (hereinafter, collectively referred to as scattered particles). Since such scattered particles collide with the clean optical surface of the optical element (for example, the X-ray optical element surface) and damage them, or adhere and accumulate to deteriorate the function and characteristics, It was a big problem.

In order to solve this problem, according to the conventional method, a thin film made of a substance having a high X-ray transmission property (for example, Be) (hereinafter referred to as a scattered particle blocking device) is provided between the plasma serving as an X-ray source and the optical element. A thin film) was installed and shielded to prevent scattered particles from reaching the optical element.
As another method, a scattered particle control member is provided near the plasma or the target member to reduce the distribution of the scattered particle emission amount in the X-ray extraction direction (Japanese Patent Application No. 6-21).
6131).

If, for example, a scattered particle control member 101 as shown in FIG. 1 is provided in the vicinity of the plasma generation position, the angular distribution of the scattered particle emission amount changes from the distribution shown by the broken line in FIG. 2 to the distribution shown by the solid line. Changes to. Scattered particle control member 1
01 is made of stainless steel with a thickness of 0.4 mm and has a shape having an opening as shown in the figure. Plasma 105
Are generated at a position about 1 mm from the end in the opening.
At this time, if the X-ray extraction direction is set to a direction having an angle larger than 30 degrees, the amount of scattered particles emitted in the X-ray extraction direction can be significantly reduced.

Further, in addition, by filling a gas having a low atomic number with a high X-ray transmittance (for example, He gas) in a vacuum container or forming a gas flow of the gas, scattered particles are scattered. Method to prevent (JP-A-63
-292555) are proposed.

[0007]

All of the above methods can be used together. An example is shown in FIG. The plasma generator is as shown in FIG. The X-ray extraction direction is a direction of 45 degrees from the normal direction at the irradiation position of the laser beam 309 of the target member 303, and the amount of scattered particles is reduced to about 1/10 of that in the case where the scattered particle control member 301 is not provided.

A gas for preventing scattered particles having a high X-ray transmittance is filled in the vacuum container, and the scattered particles are blocked by scattering with gas molecules. The scattered particle blocking members 304, 305, and 306 having openings are arranged so that the openings cover a solid angle range in which the X-ray extraction filter (an example of an optical element) 310 is seen from the plasma 311, and the scattered particles are gas molecules. Therefore, the X-ray extraction filter 310 does not reach the X-ray extraction filter 310 due to the scattering.

In this case, however, the scattered particles are scattered by the filled gas even in the space before reaching the scattered particle blocking member 304. For example, Kr gas is 0.1 torr
In the case of being filled, the angular distribution shown by the solid line in FIG. 2 changes to the angular distribution like the one-dot chain line at a position 100 mm from the plasma. In this way, the angular distribution controlled by the scattered particle control member 301 so as to reduce the scattered particles in the X-ray extraction direction changes because the scattered particles are scattered by the filling gas before reaching the scattered particle blocking member 304. As a result, there is a problem that the effect of the scattered particle control member 304 is canceled.

The present invention has been made in view of the above problems, and it is possible to effectively use the filled gas for preventing scattered particles and the scattered particle blocking member without reducing the effect of the scattered particle controlling member. Then, as a result, it aims at providing the X-ray generator which can be used stably for a long time.

[0011]

Therefore, the first aspect of the present invention is to "generate X-rays by irradiating a target member in a depressurized vacuum container with an excitation energy beam to form plasma and extracting X-rays from the plasma. An apparatus for controlling the directional distribution of the amount of scattered particles emitted from the target member and / or the plasma to reduce the amount of scattered particle emitted in the X-ray extraction direction. A scattering particle blocking member having an opening, which is a member for preventing the scattered particles from colliding, adhering to or accumulating on an optical element installed in the vacuum container, is provided. The energy beam or the X
In the X-ray generator provided between the plasma and the optical element so that the rays pass through the opening, the pressure in the first region from the plasma to immediately before the scattered particle blocking member is relatively small. Then, a gas separation mechanism for relatively increasing the pressure in the second region from the scattered particle blocking member to the optical element is provided, and the gas introduction for introducing the scattered particle blocking gas into the second region. An X-ray generator having a mouth is provided (Claim 1).

The present invention is secondly "The pressure separating mechanism is a member for separating at least the vacuum evacuation mechanism connected to the first region and the first region and the second region and connecting both regions. An X-ray generator according to claim 1, further comprising: a separating member having a minute opening, wherein the minute opening is arranged so that the energy beam or the X-rays can pass therethrough. Item 2) ”is provided.

In addition, a third aspect of the present invention is that "the pressure separation mechanism includes at least a vacuum exhaust mechanism connected to the first region, a member for separating the first region and the second region, and a member joined to the member. And a scattered particle blocking member having a minute opening connecting the two regions, and the minute opening is arranged so that the energy beam or the X-ray may pass therethrough. The X-ray generator according to claim 1 (claim 3) "is provided.

In a fourth aspect of the present invention, "the scattered particle blocking member comprises at least a plurality of plate-shaped members having openings or a member having a plurality of openings. X-ray generator (claim 4) ". Further, the present invention fifthly provides an "X-ray generator (claim 5)" according to claim 4, wherein the scattered particle blocking member includes a duct having a baffle.

In a sixth aspect of the present invention, "the X-ray generator according to the fifth aspect is provided with a gas inlet for introducing a gas for preventing scattered particles into the duct. )"I will provide a. In the seventh aspect of the present invention, "the pressure separation mechanism includes at least a vacuum exhaust mechanism connected to the first region, and a scattered particle blocking member having a duct provided with a baffle and a gas inlet. An X-ray generator according to claim 1 is provided.

[0016]

DETAILED DESCRIPTION OF THE INVENTION The X-ray generator of the present invention (claim 1)
(7) In the pressure separation, the pressure in the first region from the plasma to immediately before the scattered particle blocking member is made relatively small, and the pressure in the second region from the scattered particle blocking member to the optical element is made relatively high. Since the mechanism is provided and the gas introduction port for introducing the gas for preventing the scattered particles is provided in the second region, the filled gas and the scattered particle blocking member can be obtained without reducing the effect of the scattered particle control member. Is effectively used, and as a result, the device can be used stably for a long time.

In order to enhance the control effect of the scattered particle control member and increase the effect that the apparatus can be used stably for a long time, the pressure separating mechanism according to the present invention is, for example, at least the first A mechanism provided with a vacuum evacuation mechanism connected to one region and a separating member that separates the first region and the second region and that has a minute opening connecting both regions is preferable, and the minute opening is described above. The energy beam or the X-rays are preferably arranged so as to pass therethrough (claim 2).

Alternatively, similarly, as the pressure separating mechanism according to the present invention, at least a vacuum evacuation mechanism connected to the first region, a member for separating the first region and the second region, and the member are provided. A mechanism provided with the above-mentioned scattered particle blocking member, which is a scattered particle blocking member having a minute opening connecting the two regions, is preferable, and the energy beam or the X-ray passes through the minute opening. It is preferable to dispose (claim 3).

In order to increase the effect of preventing scattered particles, it is preferable that the scattered particle preventing member according to the present invention is provided with at least a plurality of plate-shaped members having openings or a member having a plurality of openings. 4). Alternatively, similarly, as the scattered particle blocking member according to the present invention, one provided with a duct having a baffle is preferable (claim 5).

Further, in order to enhance the control effect of the scattered particle control member and the scattered particle blocking effect, it is preferable to provide a gas inlet for introducing a gas for scattering particle blocking into the duct according to the present invention. (Claim 6). Further, by strengthening the control effect of the scattered particle control member,
In order to increase the effect that the device can be used stably for a long time, the pressure separation mechanism according to the present invention includes, for example, at least a vacuum exhaust mechanism connected to the first region, a baffle and a gas inlet. And a scattering particle blocking member having a duct provided with (Claim 7).

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 4 is a schematic partial block diagram showing the main part of the X-ray generator of this embodiment. A YAG laser beam (an example of an excitation energy beam) 409 passes through a condenser lens 408, and a tape-shaped tantalum target (an example of a target member).
It is focused on the surface of 403.

The tantalum target 403 has a thickness of 15 μm.
When the plasma is generated, the reel L is rotated by a driving means (for example, a motor, not shown) so that the laser light is not repeatedly focused on the same position on the tape. By winding the tape, the focus position of the laser is changed. The moving speed of the tantalum tape is such that the tape moves by a distance equal to or more than the diameter of the hole generated in the tantalum tape due to the generation of plasma from the time when one plasma is generated until the laser light for generating the next plasma is incident. Is the speed to do.

In this embodiment, the position of plasma serving as an X-ray source does not change even if the tantalum tape moves.
The tantalum tape is sandwiched between the target holding member 402 and the scattered particle control member 401. Here, the scattered particle control member 401 is fixed, and the target holding member 402 presses the tantalum tape to the scattered particle control member 401 with a spring material (not shown). The position of the generated plasma 411 is not changed by these members 401 and 402.

YAG laser 4 on the tantalum target
09 is incident and condensed at an incident angle of 45 degrees, and the X-ray generated from the generated plasma 411 is YAG laser 409.
It is guided to the X-ray optical system from an X-ray extraction filter (an example of an optical element) 410 provided in the direction of 45 degrees on the opposite side to. Plasma 411 and X-ray extraction filter 410
Baffles 404, 405, 406, and 407 and a duct (an example of a scattered particle blocking member) 412 (to which a gas introduction pipe 413 is connected) provided with baffles 404, 405, 406, and 407 are provided between them.

Baffle 4 provided inside the duct 412
The openings of 04, 405, 406, and 407 are configured and arranged so as not to block the solid angle of the X-ray extraction filter 410 from the plasma 411.
The first region of the inside of the vacuum container 420 is evacuated to a pressure of 0.01 torr or less by a vacuum pump (an example of a vacuum evacuation mechanism, not shown) provided in the first region from the plasma 411 to immediately before the duct 412. Has been done.

Therefore, from the plasma 411 to the duct 41
The space up to 2 is kept at a pressure at which scattered particles are hardly affected by He gas, and the effect of reducing scattered particles in the direction of the X-ray extraction filter 410 of the scattered particle control member 401 is the duct (scattered particles). (Blocking member)
It is held until it reaches the opening of baffle 404 at 412.

He gas is introduced from the gas introduction pipe 413 into the interior of the duct 412 of the vacuum container 420, that is, the second region from the duct 412 to the X-ray extraction filter 410. By adjusting the amount of the introduced gas, the pressure inside the duct 412 (second region) is maintained at a pressure (for example, 0.1 to 1.0 torr) that is sufficient to prevent scattered particles and that allows sufficient X-ray transmission. ing.

Introduction of He gas as little as possible (flow rate)
In order to obtain the scattering particle prevention effect by the duct 412
The baffle 404 is made as small as possible and the baffle 40
4 should be brought as close as possible to the plasma 411 to the extent that it is not damaged by the plasma 411. In that case, not only the flow rate of He gas can be reduced, but also the distance from the baffle 404 to the X-ray extraction filter 410 becomes longer as the baffle 404 is brought closer to the plasma 411, and scattered particles in the He gas atmosphere become Since the distance traveled is long, the scattering particles can be blocked at a lower pressure. For this reason, the flow rate of He gas can be further reduced.

In this embodiment, a vacuum exhaust pump connected to the first region is used as a pressure separating mechanism for relatively reducing the pressure in the first region and relatively increasing the pressure in the second region. , A duct (also used as a scattered particle blocking member) 412 provided with a baffle and a gas inlet is used. According to the X-ray generator of the present embodiment, the effect of reducing the amount of scattered particles in the X-ray extraction direction of the scattered particle control member 401 and the amount of scattered particles by introducing and filling He gas in the vacuum container are reduced. Since the scattered particle blocking member and the effect of reducing the scattered particles newly reaching in the X-ray extraction direction due to scattering with He by the scattered particle blocking member, it can be stably used as an X-ray generator for a long time.

[0031]

As described above, according to the X-ray generator of the present invention, the effect of reducing the amount of scattered particles in the X-ray extraction direction of the scattered particle control member and the prevention of scattered particles in the vacuum container are provided. Since the effect of reducing the amount of scattered particles by introducing and filling the gas of, and the effect of reducing scattered particles newly reaching in the X-ray extraction direction due to scattering with the gas by the scattering particle blocking member, It can be used stably as an X-ray generator for a long time.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example in which a scattered particle control member 101 is provided adjacent to a Ta target (target member) 103.

FIG. 2 is a data diagram showing an example of an angular distribution of scattered particle emission amounts.

FIG. 3 is a schematic configuration diagram of a conventional X-ray generator (an example).

FIG. 4 is a schematic configuration diagram of an X-ray generator according to an embodiment.

[Explanation of symbols]

101,301,401 Scattered particle control member 102,202,302 Target member holding member 103,203,303 Target member 104,309,409 YAG laser light (an example of excitation energy beam) 304,305,306,307 Scattered particle prevention Members 404, 405, 406, 407 Baffles 308, 408 Condensing lenses 310, 410 X-ray extraction filters (an example of an optical element) 311, 411 Plasma 412 Ducts (an example of a scattering particle blocking member) 413 Gas introduction pipe or gas introduction port More than L reel

Claims (7)

[Claims] 1. An X-ray generator for irradiating an excitation energy beam to a target member in a vacuum container, which is decompressed, to form plasma, and extracting X-rays from the plasma, wherein the target member and / or the plasma A scattered particle control member for controlling the directional distribution of the amount of scattered particles emitted to reduce the amount of scattered particles emitted in the direction for extracting the X-rays is provided adjacent to or in proximity to the target member, and The energy beam or the X-ray passes through the opening through a flying particle blocking member that is a member for preventing the flying particles from colliding, adhering or accumulating on the optical element installed in the vacuum container. As described above, in the X-ray generator provided between the plasma and the optical element, the pressure in the first region from the plasma to immediately before the scattered particle blocking member is reduced. Is provided relatively small, and a pressure separating mechanism for relatively increasing the pressure in the second region from the scattered particle blocking member to the cleaning optical surface is provided, and a gas for scattering particle blocking is provided in the second region. An X-ray generator characterized in that a gas inlet for introducing the gas is provided. 2. The pressure separation mechanism includes at least a vacuum exhaust mechanism connected to the first region, and a separation member that is a member that separates the first region and the second region and that has a minute opening connecting both regions. 2. The X-ray generator according to claim 1, further comprising: and the minute aperture is arranged so that the energy beam or the X-ray can pass therethrough. 3. The pressure separating mechanism includes at least an evacuation mechanism connected to the first region, a member separating the first region and the second region, and the flying particle blocking member joined to the member. And a scattering particle blocking member having a minute opening connecting the two regions, and the minute opening is arranged so that the energy beam or the X-rays pass therethrough. Item X-ray generator. 4. The X according to claim 1, wherein the scattered particle blocking member includes at least a plurality of plate-shaped members having openings or a member having a plurality of openings.
Line generator. 5. The X-ray generator according to claim 4, wherein the scattered particle blocking member includes a duct having a baffle. 6. The X-ray generator according to claim 5, wherein the duct is provided with a gas inlet for introducing a gas for preventing scattered particles. 7. The pressure separating mechanism comprises at least an evacuation mechanism connected to the first region, and a scattered particle blocking member having a duct provided with a baffle and a gas introduction port. The X-ray generator according to claim 1.