JPH05346495A - Filter device for x-ray source - Google Patents

Abstract

PURPOSE:To obtain a filter device for an X-ray source capable of exchanging the filter easily without opening a vacuum vessel to the air. CONSTITUTION:A filter device for an X-ray source has a filter 11a contained in a vacuum vessel together with a laser plasma X-ray source 1, penetrating X-rays 4 discharged out of the laser plasma X-ray source 1 and preventing the penetration of other scattering particles than X-rays. Filters 11a, 11b and 11c are arranged in at least two regions so that when one of them is inserted in an X-ray 4 path, the other is out of the X-ray path. The device also has a drive means 12 to drive to expel the region inserted in the path out of the path and drive to insert the region 116 expelled out of the path into the path.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter device for an X-ray source, which cuts unnecessary scattered particles emitted from a laser plasma X-ray source and transmits only X-rays.

[0002]

2. Description of the Related Art The above-mentioned laser plasma X-ray source is for collecting a laser beam on an X-ray target in a vacuum container to turn a target material into a plasma and emitting X-rays from the plasma. It is used as an X-ray source such as an X-ray spectroscope. For example, in the case of an X-ray microscope, the X-rays emitted from this X-ray source are guided to the sample via X-ray optical elements such as mirrors and zone plates. However, in general, unnecessary particles such as ions and neutral particles are emitted from the laser plasma X-ray source in addition to X-rays.
The scattering of these particles may damage the X-ray optical element. Therefore, usually, a filter for cutting scattered particles is inserted in the X-ray optical path in the vacuum container so that only X-rays are transmitted and guided to the X-ray optical element.

[0003]

By the way, in the above filter, a very thin thin film is used in order to improve the X-ray transmittance. Therefore, if it is used for a long time, the filter is damaged by the collision of the scattered particles. Alternatively, scattered particles adhere to the filter, and the X-ray transmittance decreases.
Therefore, this type of filter needs to be replaced with a new filter relatively frequently. However, in the past, when the filters were replaced, each filter was manually attached and detached to and from the filter mounting position in the vacuum container. Therefore, it is necessary to open the inside of the vacuum container to the atmosphere each time the filter is replaced. Was bad.

An object of the present invention is to provide a filter device for an X-ray source, which can easily replace the filter without opening the inside of the vacuum container to the atmosphere.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to FIG. 1 showing an embodiment. In the present invention, the laser plasma X-ray source 1 is housed in a vacuum container and is emitted from the laser plasma X-ray source 1. The present invention is applied to an X-ray source filter device having a filter that transmits X-rays 4 that are transmitted through the X-rays and that blocks scattered particles other than X-rays. That is, the filter has at least two regions 11a, 1 respectively arranged such that when one is inserted in the optical path of the X-ray 4, the other is retracted from the X-ray optical path.
1b, 11c, ... Further, while the area inserted in the X-ray optical path is driven to retract from the X-ray optical path,
The drive means 12 is provided for inserting and driving the area 11b retracted from the X-ray optical path into the X-ray optical path. In particular, the invention of claim 2 is, for example, as shown in FIG. 1, a plurality of filter parts 11 arranged around the rotating disk 11 at predetermined rotation angles.
While constructing a filter from a, 11b, and 11c,
The driving means is constituted by a motor 12 that rotates the rotating disk 11 to insert each filter portion into the X-ray optical path. The invention of claim 3 is, for example, as shown in FIG.
A filter is formed by the film-shaped member 31 that extends across the X-ray optical path in a direction substantially orthogonal to the traveling direction of the X-rays 4, and a spool 33 that winds one end side of the filter 31 and the spool 33. The driving means is composed of a motor 34 for rotating and driving. Further, the invention of claim 4 further comprises a damage detecting means 14 (FIG. 1) for detecting damage of the region of the filter inserted in the X-ray optical path. Further, the invention of claim 5 is the filter X
It further comprises a transmittance detecting means 22 (FIG. 3) for detecting the X-ray transmittance in the area inserted in the linear optical path.

[0006]

For example, in FIG. 1, when the motor 12 rotates in response to a filter replacement command, the rotating disk 11 rotates and the region 11a of the plurality of filter portions 11a inserted in the X-ray optical path is X-ray. The area 11b retracted from the optical path and retracted from the X-ray optical path is inserted into the X-ray optical path.
That is, the filter is replaced. According to this, it is not necessary to open the inside of the vacuum container to the atmosphere each time the filter is replaced, and the efficiency of replacement work can be improved. Also, for example, in FIG.
When the spool 33 is rotationally driven by the motor 34, the filter 31 is driven across the X-ray optical path in a direction substantially orthogonal to the traveling direction of the X-rays 4, whereby the filter 31 is inserted into the X-ray optical path. Area is retracted from the X-ray optical path, and the area retracted from the X-ray optical path is X
It is inserted into the linear light path (filters are replaced). According to this method, one filter 31 can be used for a long time with a compact structure. Further, in the invention of claim 4, the breakage detecting means 14 detects breakage of the region of the filter inserted in the X-ray optical path. Therefore, for example, if the filter is automatically replaced on the basis of the detection output of the detecting means 14, it is possible to prevent the use of the filter that is accidentally damaged. Further, the operator may be instructed to replace the filter based on the output of the detecting means 14. Further, in the invention of claim 5, the transmittance detecting means 22 detects the X-ray transmittance in the region inserted into the X-ray optical path of the filter. Therefore, when the transmittance falls below a predetermined value, the filter is automatically replaced,
By notifying that effect, there is no possibility of using a filter having low transmittance as in the above.

Incidentally, in the section of means and action for solving the above problems for explaining the constitution of the present invention, the drawings of the embodiments are used for the purpose of making the present invention easy to understand. It is not limited to.

[0008]

【Example】

-First Embodiment- A first embodiment of the present invention will be described with reference to Figs. FIG. 1 is a conceptual diagram showing a laser plasma X-ray source and a filter device used for this X-ray source. Reference numeral 1 denotes an X-ray target housed in a vacuum container. When a laser beam 2 is focused on the target 1 from an apparatus (not shown), the target 1 is turned into plasma, and the plasma 3 causes the X-ray 4 to pass.
Is irradiated. 10 is an X-ray 4 in the vacuum container.
Is a disc-shaped silicon wafer 11 rotatably supported, which is a filter device for preventing scattered particles interposed in the optical path of
Has a plurality of circular windows (diameter of about 10 mm) made of a silicon nitride thin film on a concentric circle centered on the center of rotation.
11a, 11b, 11c, ... Are formed at a predetermined angular pitch. Each of these windows has a thickness of 0.
A filter is formed by forming a film of aluminum having a thickness of about 2 μm. The silicon wafer 11 is arranged so that any one of the filters 11a is inserted into the optical path of the X-ray 4. Here, each filter is made opaque so that visible light and infrared light emitted from the plasma 3 can be cut off.

Reference numeral 12 is a wafer driving motor (driving means).
The output shaft 12a is connected to the center of the silicon wafer 11. When the wafer 11 is rotated by a predetermined angle by the motor 12, the filter 11a inserted in the X-ray optical path is retracted from the X-ray optical path, and the next filter 11b is inserted in the X-ray optical path. Reference numeral 13 is a disk-shaped mask provided between the silicon wafer 11 and the target 1, and the circular window portion 13a provided on the upper portion of the mask 13 is used as the X-ray 4
Are arranged to pass through. In this mask 13, the scattered particles are other filters 11 b, 1 of the silicon wafer 11.
This is to prevent irradiation of 1c ...

Reference numeral 14 denotes a filter 11a in the X-ray optical path.
Is a damage detection device for detecting damage to the mask 13 and includes a light projector 14a that emits light so as to pass through the window 13a of the mask 13 and the filter 11a of the wafer 11, and a light receiver 14b that receives light that has passed through the filter 11a. Have. The light projector 14a may be anything such as a light emitting diode, a laser diode, or a lamp. Further, an optical system such as a concave lens may be arranged in front of the projector 14a so that the entire area of the filter 11a can be illuminated. Since the filters 11a, ... Are opaque as described above, when the filter 11a is damaged by scattered particles such as ions or neutral particles emitted together with the X-ray 4, it is compared with that before the damage. As a result, the amount of light received by the light receiver 14a increases. Therefore, it is possible to detect whether or not the filter is damaged by the output of the light receiver 14b. The output of the light receiver 14b is input to the control circuit 15 shown in FIG. 2, and the control circuit 15 controls the motor 12 based on this.

Next, the operation of the embodiment will be described. When the target 1 is irradiated with the laser beam 2 from a device (not shown), the target 1 is turned into plasma and the plasma 3 is irradiated with X-rays 4. After passing through the window 13a of the mask 13, the X-ray 4 passes through the filter 11a of the silicon wafer 11 and is guided to an X-ray optical element (not shown). On the other hand, scattered particles other than X-rays emitted from the target 1 are filtered by the filter 11
It is blocked by a, which prevents damage to the X-ray optical element.

When the filter 11a is used for a certain period of time, the collision of the scattered particles causes the filter 11a to be damaged. When the filter 11a is damaged, the output of the light receiver 14a of the damage detection device 14 increases as described above, and the control circuit 15 causes the motor 12 to rotate in a predetermined direction by a predetermined amount. As a result, the silicon wafer 11 rotates in the direction A in the figure by a predetermined angle, the filter 11a inserted in the X-ray optical path retracts from the X-ray optical path, and
The next filter 11b is inserted in the X-ray optical path. That is, the filter is replaced. Since this filter replacement operation is performed in the vacuum container, it is not necessary to open the vacuum container to the atmosphere at the time of replacement, and the damaged filter 11a is retracted and a new filter 1 is used.
Since 1b can be inserted at the same time, the efficiency of filter replacement work can be improved as compared with the conventional case. Also, particularly in this embodiment,
Since the presence or absence of damage to the filter is detected and the filter is automatically replaced when the damage is detected, the inconvenience of not using the damaged filter and using the damaged filter as it is can be prevented.

In the above description, when the breakage is detected, the filter is automatically replaced. For example, when the breakage of the filter is detected, the fact is visually or audibly notified, and the operator is notified by the notification. If any operation is performed, the motor 12 may be rotated to replace the filter.

-Second Embodiment- A second embodiment of the present invention will be described with reference to FIG. In this embodiment, an X-ray detector (transmittance detecting means) 22 is provided in place of the breakage detecting device 14, and the filter is replaced when the decrease in the X-ray transmittance of the filter is detected. The same parts as those in FIG. 1 are designated by the same reference numerals, and the differences will be mainly described. In FIG. 3, 21 is a movable stage that can move in the direction B in the figure, 22 is an X-ray detector provided on the movable stage 21, and the X-ray detector 22 is inserted in the X-ray optical path by the movement of the movable stage 21. It is supposed to be removable.
The X-ray detector 22 is composed of, for example, an X-ray diode, and detects the X-ray dose transmitted through the filter 11a on the silicon wafer 11. On the other hand, an energy meter 23 detects the laser energy of the laser light 2 split by the beam splitter 24.

Next, the operation of the embodiment will be described. After inserting the new filter 11a into the X-ray optical path, the moving stage 21 is moved to insert the X-ray detector 22 into the X-ray optical path, and the laser beam 2 is applied to the X-ray target 1 to emit the X-ray 4 To release. At this time, the energy meter 23 detects the laser energy of the laser light 2 and the X-ray detector 22 detects the transmitted X-ray dose of the filter 11a, and these detected values are stored in, for example, the memory in the control circuit 15. To be done. Next, the moving stage 21 is moved to move X
The line detector 22 is retracted from the X-ray optical path.

After performing X-ray radiation several times in this state,
The X-ray detector 22 is inserted again into the X-ray optical path, and the laser energy and the X-ray dose are detected in the same manner as described above. The detection result is compared with the previously stored value in the control circuit 15,
Although the detected value of the laser energy is the same as the stored value, when the detected value of the X-ray dose is smaller than the stored value by a predetermined amount or more, the X-ray transmittance by the filter 11a is lowered due to the attachment of scattered particles from the plasma 3. The motor 12 is driven. As a result, the silicon wafer 11 rotates by a predetermined amount, the filter 11a is retracted from the X-ray optical path as described above, and a new filter 11b is inserted into the X-ray optical path.

In the above, the X-ray detector 22 is inserted in the X-ray optical path to detect the transmitted X-ray dose. However, as shown in FIG. 4, for example, the vicinity of the filter 11a (however,
The X-ray detector 22 may be arranged at a position outside the X-ray optical path) to detect the scattered X-ray dose from the filter. This focuses on the fact that the larger the amount of scattered particles attached to the filter, the larger the scattered X-ray dose. Therefore, in this case, the scattered X-ray dose is sequentially detected by the X-ray detector 22, and the laser energy is increased. If the output of the X-ray detector 22 exceeds a predetermined value even though the detected value of the filter is the same as the stored value, it is determined that the amount of scattered particles attached to the filter is large and the X-ray transmittance of the filter has decreased. Should be exchanged. According to this, it is possible to save the labor of moving the X-ray detector 22 into and out of the X-ray optical path one by one, so that the efficiency can be improved.

In the second embodiment, the control circuit automatically compares the detected value of the laser energy and the transmitted X-ray dose (scattered X-ray dose) with the stored value and the motor drive command based on the comparison result. Or an operator may do it. Further, if the stability of the laser energy of the laser light 2 is guaranteed, the energy meter 23 is unnecessary. Further, both the means for detecting the transmittance of the filter and the means for detecting damage to the filter may be provided, and the filter may be replaced when either the decrease in the transmittance or the damage is detected.

-Third Embodiment- A third embodiment using a roll-up type filter will be described with reference to FIG. In FIG. 5, reference numeral 31 is a filter according to this embodiment, which is formed by forming a film of aluminum having a thickness of about 0.2 μm on a Mylar film having a thickness of about 1 μm. The filter 31 is wound around the spool 32 in advance, and is disposed so as to extend across the X-ray optical path in the direction orthogonal to the X-ray traveling direction, and the tip end thereof is wound around the take-up spool 33. The take-up spool 33 is the motor 3
It is rotationally driven by 4. Further, reference numeral 35 is a mask having a window portion 35a for preventing the scattered particles from being guided to a region other than the X-ray optical path of the filter 31.

When the X-ray target 1 is irradiated with the laser beam 2 to emit X-rays 4 in the same manner as described above, the X-rays 4 pass through the window portion 35a of the mask 35 and then pass through the filter 31. It is guided to an X-ray optical element (not shown). Therefore, the scattered particles other than the X-rays emitted from the target 1 are blocked by the filter 31, so that the X-ray optical element can be prevented from being damaged. When the breakage detecting device 14 detects breakage of the filter 31, the motor 34 is rotated in a predetermined direction by a predetermined amount, whereby the take-up spool 33 is rotated and the filter 31 is taken up, and the X-ray of the filter 31 is taken. The area inserted in the optical path, that is, the damaged area is retracted from the X-ray optical path, and the area retracted from the X-ray optical path of the filter 31 (non-damaged area) is inserted into the X-ray optical path. .. That is, the filter is replaced. Since this filter replacement operation is performed in the vacuum container, it is not necessary to open the vacuum container to the atmosphere at the time of replacement in the same manner as described above, and the damaged filter area can be saved and a new area can be inserted. Since they can be performed at the same time, the efficiency of filter replacement work can be improved.

In particular, if the filter is of the winding type as in this embodiment, one filter 31 can be used for a long time with a compact structure. In the third embodiment as well, a transmittance detector may be provided instead of the damage detection device, or both may be provided.

In the first and third embodiments, the transmittance of the filter is detected to detect whether the filter is damaged. However, the reflected light of the filter is detected to detect the damage. May be. That is, the irradiation light of the projector is
Although it is reflected by the X-ray optical path insertion portion of the filter, the light receiver is arranged at a position where the reflected light can be received, and if the amount of light received by the light receiver is below a predetermined value, it is determined that the filter is damaged. You can do it like this.

[0023]

According to the present invention, the drive means retracts the area of the filter inserted in the X-ray optical path from the X-ray optical path and inserts the area retracted from the X-ray optical path into the X-ray optical path. Therefore, it is not necessary to open the inside of the vacuum container to the atmosphere each time the filter is replaced, and the replacement work efficiency can be improved. In particular, according to the invention of claim 3, the filter is constituted by the film-like member extending across the X-ray optical path in the direction substantially orthogonal to the traveling direction of the X-ray, and the spool is wound at one end side thereof. Since the filter is wound and the filter is replaced, the filter device can be made compact and one filter can be used for a long time. Claim 4
According to the invention, since the breakage of the region of the filter inserted in the X-ray optical path is detected, for example, the filter can be automatically replaced or the filter can be replaced based on the detection result. This will prevent you from accidentally using a damaged filter. Further, according to the invention of claim 4, since the X-ray transmittance in the region of the filter inserted in the X-ray optical path is detected, the filter is automatically replaced when the transmittance becomes a predetermined value or less. By performing the above or notifying that effect, there is no possibility of using a filter having a low transmittance.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of an X-ray source filter device according to the present invention.

FIG. 2 is a block diagram showing a configuration of a control system.

FIG. 3 is a schematic configuration diagram showing a second embodiment of an X-ray source filter device.

FIG. 4 is a diagram showing a modification of FIG.

FIG. 5 is a schematic configuration diagram showing a third embodiment of an X-ray source filter device.

[Explanation of symbols]

 1 X-ray target 2 Laser light 3 Plasma 4 X-ray 10 Filter device 11 Silicon wafer 11a, 11b, 11c, 31 Filter 12, 34 Motor 13, 35 Mask 14 Damage detection device 21 Moving stage 22 X-ray detector 23 Energy meter 24 Beam splitter 32 Spool 33 Take-up spool

Claims (5)

[Claims] 1. An X which is housed in a vacuum container together with a laser plasma X-ray source and is emitted from the laser plasma X-ray source.
In a filter device for an X-ray source, which has a filter that transmits a ray and blocks a scattered particle other than an X-ray, when the one of the filters is inserted into the optical path of the X-ray, the other is an X-ray optical path. Has at least two areas respectively arranged so as to be retracted from the X-ray optical path, and drives the area inserted into the X-ray optical path from the X-ray optical path, and the area retracted from the X-ray optical path. An X-ray source filter device comprising drive means for inserting and driving in an X-ray optical path. 2. The filter comprises a plurality of filter portions arranged around a rotary disc at predetermined rotation angles, and the drive means rotates the rotary disc to move each filter portion to the X-axis. The filter device for an X-ray source according to claim 1, wherein the filter device is configured by a motor that is inserted into a linear optical path. 3. The filter is composed of a film-shaped member that extends across the X-ray optical path in a direction substantially orthogonal to the optical axis of the X-ray, and the driving means includes one end side of the filter. 2. A spool for winding up and a motor for driving the spool to rotate.
The filter device for an X-ray source as described in 1. 4. The filter for an X-ray source according to claim 1, further comprising damage detection means for detecting damage to a region of the filter inserted in the X-ray optical path. apparatus. 5. The X according to claim 1, further comprising transmittance detecting means for detecting an X-ray transmittance of a region of the filter inserted in the X-ray optical path. Source filter device.