JPH09320793A - X-ray generator and X-ray device - Google Patents

Abstract

(57) An object of the present invention is to provide an X-ray generator using a plasma X-ray source that eliminates or suppresses X-ray intensity fluctuations and stabilizes the X-ray intensity. In a X-ray generator for generating plasma by irradiating a target member in a depressurized vacuum container with an excitation energy beam and extracting X-rays from the plasma, the excitation energy beam for forming the plasma 103.
Before irradiation, the excitation energy beam 102 has a lower energy than the irradiation of the excitation energy beam 102 for forming the plasma 103 at a planned irradiation position of the target member 111 or an area including the planned irradiation position. An X-ray generator characterized in that a mechanism for previously irradiating a low energy density excitation energy beam 101 is provided.

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, an X-ray exposure apparatus, and the X-ray generator equipped with the X-ray generator. The present invention relates to a line device.

[0002]

2. Description of the Related Art X-ray generators generally used as X-ray sources for X-ray apparatuses such as X-ray microscopes, X-ray exposure apparatuses, and X-ray analysis apparatuses include particle beams in addition to synchrotron radiation. X-ray tube for generating X-rays by colliding the target member with a target member, or a plasma X-ray source for generating X-rays by converting the target member into plasma by discharge or irradiation of an excitation energy beam (for example, laser) (for example, , Laser plasma X-ray source) and the like.

Of these, in a plasma X-ray source, when an excitation energy beam (for example, a laser beam) is focused on a target member placed in a depressurized vacuum container and irradiated, the target member is rapidly turned into plasma. X-rays with extremely high brightness are radiated (emitted) from this plasma. This plasma X-ray source is expected as an X-ray source of an X-ray generator capable of generating X-rays having a higher brightness than the X-ray tube, and being much smaller than the synchrotron radiation.

Generally, an X-ray source is required to have stability with respect to its intensity, and it is preferable that the X-ray intensity is stable even when the above plasma is used as the X-ray source. For example,
In the X-ray microscope, it is preferable that the intensity of the X-rays that illuminate the observation sample be constant from the viewpoint of image observation, and in the X-ray analyzer, the intensity of the X-rays that are irradiated to perform accurate analysis is constant. Is desired.

Further, when fine processing is performed by an X-ray exposure apparatus, it is preferable that the X-ray intensity is constant because the reliability of the processing decreases unless the X-ray exposure amount is kept constant. At present, a method of controlling the intensity of an energy beam for exciting plasma is used as a method of controlling the intensity of X-rays from an X-ray source.

When the dose of X-rays is a problem, the X-ray dose actually generated is detected by a detector, and the X-ray dose becomes a predetermined value while monitoring the X-ray dose.
Irradiation is performed by controlling the line intensity (that is, the intensity of the excitation energy beam), the irradiation time and the number of times of irradiation.

[0007]

In the plasma X-ray source, there is no great difference in the thickness of the target member for irradiating the energy beam, whether it is thick or thin. For example, when tantalum is used as the target member, The thickness of the member is 100μ
The intensity of the radiated X-rays is substantially the same whether m or 1 μm.

This means that "the surface of the target member or the surface layer (in the case of tantalum, the layer having a thickness of 1 μm or less from the outermost surface) is involved in the formation of plasma and, in turn, the emission of X-rays. "," Slight contamination on the surface or surface layer, the presence of impurities, etc. affect the plasma to be formed and the intensity of radiated X-rays to change them. "

However, the extent of fluctuations in X-ray intensity due to dirt on the surface of the target member cannot be known at present until X-rays are actually generated. In other words, the intensity of X-rays generated is within a certain range. It can only be predicted and contains uncertainties until it is actually generated. Therefore, the method of controlling the X-ray intensity, which is performed by controlling the intensity of the energy beam that excites the plasma, cannot solve the X-ray intensity fluctuation.

When the conventional plasma X-ray source is used as an X-ray generator, it becomes difficult to observe an image with an X-ray microscope because the plasma X-ray source varies in X-ray intensity.
The line analyzer has a problem that it is difficult to perform accurate analysis. Further, in the case of performing fine processing with an X-ray exposure apparatus, in order to keep the X-ray exposure amount constant, the X-ray amount actually generated is detected by a detector, and the X-ray amount is monitored while monitoring the X-ray dose. There has been a problem that complicated control is required to perform irradiation by controlling the X-ray intensity (that is, the intensity of the excitation energy beam), the irradiation time and the number of times of irradiation so that the irradiation amount becomes a predetermined value.

Further, even if such complicated control is performed, the amount of irradiation does not always reach a predetermined value because the intensity of X-rays generated in the plasma X-ray source varies and the intensity of the generated X-rays cannot be accurately predicted. There was a point. The present invention
The present invention has been made in view of the above problems, and an object thereof is to provide an X-ray generator using a plasma X-ray source in which fluctuations in X-ray intensity are eliminated or suppressed and the X-ray intensity is stabilized.

Further, according to the present invention, the X-ray intensity is stabilized,
Further, an X-ray microscope equipped with an X-ray generator having a plasma X-ray source capable of highly accurately adjusting the X-ray intensity, an X-ray analyzer,
It is an X-ray device such as an X-ray exposure device, and X for easy image observation.
X-ray microscope, X-ray analyzer for easy and accurate analysis, X
X such as X-ray exposure equipment that can easily maintain a constant dose of X-ray
It is intended to provide a wire device.

[0013]

Therefore, the present invention firstly provides a method in which a target member in a decompressed vacuum vessel is irradiated with an excitation energy beam to form a plasma, and X-rays are generated from the plasma.
In the X-ray generator for extracting the radiation, before the irradiation of the excitation energy beam for forming the plasma, the irradiation target position of the excitation energy beam to the target member,
Alternatively, an X-ray generator characterized in that a mechanism for performing irradiation with an excitation energy beam having a lower energy or a lower energy density than the excitation energy beam irradiation for forming the plasma is provided in an area including the irradiation planned position ( Claim 1) "is provided.

The present invention secondly provides that "the low energy or low energy density excitation energy beam to the target member is extracted from dirt, impurities, or the plasma existing on the surface or surface of the target member. X
An X-ray generator (claim 2) according to claim 1, characterized in that it has an energy or energy density that removes substances that vary the intensity of the rays.

The third aspect of the present invention is that "the excitation energy beam for forming the plasma and the low energy or low energy density excitation energy beam are emitted from the same excitation energy beam source. An X-ray generator (claim 3) according to claim 1 or 2 is provided. A fourth aspect of the present invention provides an "X-ray generator (claim 4) according to any one of claims 1 to 3, further comprising a mechanism for changing an irradiation area of the excitation energy beam.

In a fifth aspect of the present invention, an X-ray generator according to any one of claims 1 to 4, further comprising: a mechanism for changing an irradiation position or an irradiation region of the excitation energy beam. )"I will provide a. The sixth aspect of the present invention is "X for detecting the intensity of X-rays extracted from the plasma.
An X-ray generator (claim 6) according to claims 1 to 5, characterized in that a line intensity detection mechanism is further provided.

In a seventh aspect of the present invention, "an X-ray microscope equipped with the X-ray generator according to any one of claims 1 to 6, an X-ray analyzer, and an X-ray analyzer.
An X-ray device such as a line exposure device (claim 7) is provided.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION In an X-ray generator using a plasma X-ray source according to the present invention, the target member of the excitation energy beam is irradiated before the target member is irradiated with the excitation energy beam for plasma formation. A mechanism for performing irradiation with an excitation energy beam having a lower energy or a lower energy density than the excitation energy beam irradiation for forming the plasma is provided in advance at a planned irradiation position or a region including the planned irradiation position.

For example, as shown in FIG. 1, plasma is not generated on the surface of a target material (an example of a target member) 111 that moves in the direction of the arrow in a depressurized vacuum container, but laser ablation does not occur. A pulsed laser light (an example of an excitation energy beam having a lower energy density than irradiation of an excitation energy beam for plasma formation) 101 focused so as to have an intensity density is emitted.

Then, the target material 111 is moved,
The part of the surface of the target material irradiated with the laser light 101 is made to come to the focus position of the excitation laser light (an example of the excitation energy beam for plasma formation) 102, and then the excitation laser light 102 is oscillated to generate plasma. 10
When No. 3 is generated, plasma is always generated in a portion where surface dirt is removed by laser ablation.

That is, in the X-ray generator of FIG. 1 which is an example of the present invention, the plasma 102 is always generated on the surface portion of the target material from which the stain has been removed by laser ablation, so that the generated plasma 103 generates the stain. Not affected. Therefore, in the X-ray generator of FIG.
When the plasma is excited a plurality of times with the laser light of the same energy, stable and uniform X-ray intensity can be obtained as compared with the case where the stain is not removed.

By the way, when the intensity of the X-ray to be extracted (generated) is controlled by controlling the intensity of the excitation laser beam, the X-ray can be highly accurately measured unless the influence of contamination on the surface of the target material can be eliminated. It is not possible to control the intensity. Therefore, if the dirt on the target surface is previously removed by laser ablation as in the X-ray generator shown in FIG. 1, the intensity of the X-ray generated can be adjusted with high precision by the intensity of the excitation laser.

Thus, according to the X-ray apparatus of the present invention,
By removing dirt on the surface of the target member by a mechanism that pre-irradiates the excitation energy beam with a lower energy or lower energy density than the irradiation with the excitation energy beam for plasma formation, the fluctuation of the X-ray intensity is eliminated or suppressed,
The X-ray intensity can be stabilized. Then, the X-ray intensity can be adjusted with high accuracy.

Irradiation of the low energy or low energy density excitation energy beam to the target member according to the present invention is present on the surface or surface layer of the target member.
It is preferable to have energy or energy density for removing dirt, impurities, or substances that change the intensity of X-rays extracted from the plasma (claim 2). With such a structure, the intensity of X-rays extracted from the plasma can be further stabilized.

In the X-ray generator of the present invention, when the excitation energy beam for forming the plasma and the low energy or low energy density excitation energy beam are emitted from the same excitation energy beam source, Is preferable because it can be downsized and the price can be reduced (Claim 3). In the X-ray generator of the present invention, it is preferable that a mechanism for changing the irradiation area of the excitation energy beam is further provided (Claim 4).

With this structure, even when the target members made of different materials are used according to the purpose, the excitation energy beam irradiating the target members made of the respective materials (1) has an intensity density enough to form plasma. So that (2) the intensity density is such that dirt on the surface of the target member can be removed, or (3) dirt, impurities, or X-rays extracted from the plasma present on the surface or surface of the target member. The irradiation area can be adjusted so that the intensity density is such that a substance that changes the intensity of can be removed.

When it is found that the X-ray intensity fluctuation suppressing effect is small, the suppressing effect can be increased by adjusting the irradiation area. In the X-ray generator of the present invention, it is preferable that a mechanism for changing the irradiation position or irradiation region of the excitation energy beam is further provided (Claim 5). With such a configuration, by changing the irradiation position or irradiation area to the target member, it is possible to repeatedly use the target member without exchanging it. As a result, the continuous use time of the X-ray generator or the maintenance-free time can be increased.

Further, when it is found that the X-ray intensity fluctuation suppressing effect is small, the suppressing effect can be increased by changing the irradiation position or irradiation region. In the X-ray generator of the present invention, X extracted from the plasma
It is preferable to further provide an X-ray intensity detection mechanism for detecting the intensity of the rays (claim 6). With such a configuration, when there is a variation in the intensity of the X-rays extracted from the plasma, the variation is detected in real time, and irradiation of the excitation energy beam to the target member (for plasma formation and / or prevention of intensity variation of the X-rays). X-ray intensity by (1) adjusting the irradiation intensity or its intensity density, (2) changing the irradiation area, or (3) changing the irradiation position or irradiation area. Can be eliminated or suppressed, and the X-ray intensity can be reliably stabilized.
Then, the X-ray intensity can be surely adjusted with high accuracy.

It is preferable to provide an excitation energy beam detection mechanism for detecting the intensity of the excitation energy beam (for plasma formation and / or for preventing X-ray intensity fluctuation) with which the target member is irradiated. If such a mechanism for detecting the excitation energy beam is provided, whether the intensity fluctuation of the X-ray is caused by (a) the intensity reduction of the excitation energy beam for plasma formation or the intensity density thereof, or (b) the intensity variation of the X-ray. To reduce the intensity of the excitation energy beam in order to prevent the above, or (c) the irradiation area, irradiation position, or irradiation region of the excitation energy beam to prevent fluctuations in the intensity of X-rays is inappropriate. It can be distinguished whether it is a thing.

In the case of (a), the intensity of the excitation energy beam for plasma formation or its intensity density is increased, and in the case of (b), the excitation for preventing the intensity fluctuation of X-rays. By increasing the intensity of the energy beam or its intensity density, or, in the case of (c), changing the irradiation area, irradiation position, or irradiation region of the excitation energy beam to prevent X-ray intensity fluctuations. Thereby, the X-ray intensity can be stabilized more reliably. Then, the X-ray intensity can be adjusted more reliably and with high accuracy.

Incidentally, depending on the respective situations of (a), (b) and (c),
It goes without saying that the operations (a), (b), and (c) are continued until the X-ray intensity detected by the X-ray intensity detection mechanism is recovered. An X-ray apparatus provided with an X-ray generator according to the present invention having a plasma X-ray source capable of stabilizing the X-ray intensity and adjusting the X-ray intensity with high precision is, for example, an X-ray microscope which facilitates image observation. The present invention can be used by making full use of the features of the X-ray analysis apparatus such as an X-ray analysis apparatus capable of easily performing accurate analysis and the X-ray exposure apparatus capable of easily maintaining a constant X-ray exposure amount.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0033]

EXAMPLE FIG. 2 shows a schematic partial configuration diagram of an X-ray generator of this example using tape-shaped tantalum as a target member. YAG laser light (an example of an excitation energy beam having a lower energy or lower energy density than the excitation energy beam for forming a plasma) 201 and YAG laser light (an example of an excitation energy beam for forming a plasma) 2
02 is transmitted through the entrance window 232 while being condensed by the condenser lens 235, and enters into the vacuum container 234.

By collecting the YAG laser light 201, a tantalum target (an example of a target member) 211 is obtained.
The intensity density is such that laser ablation occurs on the surface of. Then, this laser ablation removes stains on the surface of the target member. Also, YAG
The laser beam 202 is focused on the surface of the tantalum target from which the dirt on the surface is removed by the laser ablation to form plasma 203.

The tantalum target 211 has a thickness of 15 μm.
When the plasma is generated, the reel 212 and the pinch roller 213 are rotated by a driving unit (for example, a motor, not shown) so that the laser light is not repeatedly focused on the same position on the tape. Moving the tantalum tape. The movement speed of the tantalum tape is the speed at which the tape moves 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. And the speed at which the position where the YAG laser beam 202 is focused is included in the target region already irradiated with the YAG laser beam 201 (the target region where the surface contamination has been removed by the laser ablation). Is.

The YAG laser 202 is incident on the tantalum target 211 at an incident angle of 45 degrees and condensed, and the X-rays 204 generated from the generated plasma 203 are provided in the direction of 45 degrees on the side opposite to the YAG laser 202. The X
It is guided to the X-ray optical system from the line extraction window 231. In this embodiment, the incident angle of the exciting YAG laser 202 and the extraction angle of the X-ray 204 are both 45 degrees, but the angle is not limited to this angle.

In the present embodiment, the laser light applied to remove the dirt on the target surface is the YAG laser light, but the laser light is not limited to this and may be another laser light such as an excimer laser. In the present embodiment, the moving direction of the tape target is one direction and the position on the target where the laser ablation is performed is one position. However, the moving direction of the tape target 211 is bidirectional,
Laser ablation may be performed by switching on the two targets on the left and right of the plasma generation position, or simultaneously.

In this embodiment, the light source of the YAG laser light 201 for removing dirt by ablation is different from the YAG laser light 202 for exciting the plasma, but a part of the excitation laser light 202 is changed by a beam splitter or a mirror. Alternatively, one laser light source can be used by taking out all of them and performing ablation.

When a part or all of the excitation laser beam 202 is extracted and ablated, the irradiation area on the target 211 is made larger than the irradiation area for irradiation for plasma formation. The energy density of irradiation can be reduced more than that at the time of formation, and the laser beam intensity density can be set to a level at which ablation occurs.

In this embodiment, the target shape is a tape shape, but it may be a cylindrical shape, a plate shape or the like. Further, in the present embodiment, the laser light irradiation position (inside the vacuum container) for moving the target continuously in the vacuum container and cleaning the target surface by laser ablation, and the laser light for generating the plasma. It is separate from the irradiation position (position inside the vacuum container).

However, the present invention is not limited to this.
By moving the target intermittently and temporally shifting the laser light for ablation and the laser light for exciting the plasma, the irradiation position of the laser light for ablation and the irradiation position of the laser light for exciting the plasma are inside the vacuum container. May be at the same position or area. In this embodiment, the contamination of the surface of the target member where plasma is generated can be removed in advance by laser ablation, whereby fluctuations in X-ray intensity can be eliminated or suppressed, and X-ray intensity can be stabilized. Then, the X-ray intensity can be adjusted with high accuracy.

That is, according to the X-ray generator of this embodiment,
If the energy of the excitation laser light is constant, the intensity of X-rays can be kept constant, and the intensity of X-rays generated by controlling the energy of the excitation laser can also be controlled accurately. .

[0043]

As described above, according to the X-ray generator of the present invention, fluctuations in X-ray intensity are eliminated or suppressed,
The X-ray intensity can be stabilized. Then, the X-ray intensity can be adjusted with high accuracy. Further, according to the X-ray apparatus of the present invention, the X-ray intensity is stabilized, and the X-ray generator having the plasma X-ray source capable of adjusting the X-ray intensity with high precision is provided, and the X-ray observation facilitates image observation. Each feature can be utilized as an X-ray device such as a line microscope, an X-ray analysis device that can easily and accurately analyze, and an X-ray exposure device that can easily maintain a constant X-ray exposure amount.

[Brief description of drawings]

FIG. 1 is an X-ray generator having a structure in which a laser beam 101 with reduced energy or energy density is previously irradiated onto a target irradiation position of a plasma generation laser beam 102 on a surface of a target material (target member) 111 ( It is a schematic partial block diagram of an example).

FIG. 2 is a schematic partial configuration diagram of an X-ray generator according to an embodiment.

[Explanation of symbols]

101, 201 Laser light (an example of an excitation energy beam having lower energy or energy density lower than that of an excitation energy beam for plasma formation) 102, 202 Excitation laser light (an example of excitation energy beam for plasma formation) 103, 203 Plasma 104 , 204 X-ray 111, 211 Target material (an example of target member) 131, 231 X-ray extraction window 212 reel 213 pinch roller 232 laser light incident window 234 vacuum container 235 condensing lens or more

Claims (7)

[Claims] 1. An X-ray generator for irradiating an excitation energy beam to a target member in a depressurized vacuum container to form plasma and extracting X-rays from the plasma, wherein the excitation energy beam irradiation for forming the plasma is performed. Before performing, at the planned irradiation position of the excitation energy beam to the target member, or in the region including the irradiation planned position,
An X-ray generator comprising a mechanism for performing irradiation with an excitation energy beam having a lower energy or a lower energy density than the irradiation of the excitation energy beam for forming the plasma. 2. The low-energy or low-energy-density excitation energy beam on the target member changes the intensity of dirt, impurities, or X-rays extracted from the plasma existing on the surface or surface of the target member. The X-ray generator according to claim 1, having energy or energy density for removing a substance. 3. The excitation energy beam for forming the plasma and the excitation energy beam having the low energy or low energy density are emitted from the same excitation energy beam source.
Or the X-ray generator described in 2. 4. The mechanism for changing the irradiation area of the excitation energy beam is further provided.
X-ray generator of statement. 5. The X-ray generator according to claim 1, further comprising a mechanism for changing an irradiation position or an irradiation region of the excitation energy beam. 6. The X-ray generator according to claim 1, further comprising an X-ray intensity detection mechanism for detecting the intensity of X-rays extracted from the plasma. 7. An X-ray device, such as an X-ray microscope, an X-ray analysis device, and an X-ray exposure device, which is equipped with the X-ray generation device according to claim 1.