JPH0862399A - Vacuum device - Google Patents

Abstract

PURPOSE: To downsize and simplify a vacuum device piping which can minimize the conductance and has a vacuum exhaust hole able to have a large exhausting speed, in a vacuum device having an optical system in which the differential exhaust by an orifice can not be performed. CONSTITUTION: A conduit 6c is provided between a lower vacuum-vacuum vessel 6a and a higher vacuum-vacuum vessel 6b is which differential exhaust is performed. The conduit 6c is formed out of a capillary 11 for minimizing the conductance between both the vacuum vessels and a capillary support part 16 for supporting the capillary, and a vacuum exhaust hole 12 is provided on the side part of the conduit 6c. By the adaptation of the capillary 11 protruded from the capillary support part 16 in the conduit 6c, the exhaust hole 12 can be provided on the conduit 6c while the structure of the conduit 6c is kept in a small size, and the conductance between the high vacuum-vacuum vessel 6b and an exhauster 7a can be made sufficiently large.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a vacuum apparatus including an optical system with differential evacuation.

[0002]

2. Description of the Related Art Vacuum is defined as "a state in a space filled with a gas having a pressure lower than that of a normal atmosphere (not a pressure itself)" (JIS Z8126). But,
Even if it is "low", its degree varies. In the field of vacuum, the vacuum regions are divided as shown in Table 1 according to the difference in the pressure range. In recent years, along with the rapid progress of vacuum technology, vacuum devices utilizing each vacuum region have been developed in various fields.

[0003]

[Table 1]

In designing a vacuum device for creating a vacuum atmosphere, the vacuum exhaust system must be selected in addition to other points to be noted in the design of the device. Items to be met when selecting the optimum vacuum exhaust system for each application are (1) vacuum quality, (2) ultimate pressure and operating pressure, (3) exhaust speed, (4) vacuum container size and material. , (5) Type of introduced gas, 5 items are listed. Specifically, in (1), what kind of component remains as a residual gas in the vacuum container and to what extent it is unsatisfactory, and the characteristics of the pump are considered. Regarding (2), the ultimate pressure and operable pressure range are determined by the type of pump, the amount of gas released from the wall surface inside the vacuum vessel and the internal mechanism, and it is necessary to consider the equilibrium pressure estimated in consideration of these. . Regarding (3), when selecting a vacuum system, pay attention to the time required to bring the pressure inside the vacuum container from atmospheric pressure to the operating pressure, and the amount of released gas and introduced gas in the container. Regarding (4), the volume determines the evacuation time in the low vacuum region, and the surface area affects the evacuation time in the high vacuum region, and the amount of released gas varies greatly depending on the material and surface processing. Should be considered and considered. Regarding (5), although related to (1) and (3), it should be noted that the material of the vacuum container itself and the elements in the container may be limited depending on the type of introduced gas.

Basically, the vacuum system is selected as described above, and the vacuum device is designed and manufactured. However, in recent years
Since vacuum systems are becoming more and more complicated and diversified in vacuum devices that are being developed, more functional vacuum elements are desired. For example, in a conventional scanning electron microscope (SEM), the target could not be inspected at atmospheric pressure and the sample could not be seen in the natural environment, but the differential pumping method, that is, the pumping speed of the pump On the other hand, an apparatus capable of inspecting a sample under atmospheric pressure or low vacuum has been developed by taking a method of increasing the pressure difference between both sides of the conduit by significantly reducing the conductance of the conduit. Here, an orifice having a very small opening is generally used to remarkably reduce the conductance. When differential evacuation is performed using an orifice, the orifice is often used in a multi-stage configuration, but since it can be manufactured with a short length on the optical path, the overall configuration of the device is small and simplified.

Regarding differential exhaust using an orifice,
For example, "Practical Vacuum Technology Handbook", Industrial Technology Service Center, issued Nov. 2, 1990, pages 96 to 102, JP-A-1-183407, JP-A-1-309243.
Publication, JSPE-57-07'94-07-1178.
"Environmentally Controlled Scanning Electron Microscope", pages 42-45.

Such an orifice is applicable when an optical system having a small beam diameter and a small scanning range is satisfied as in the SEM. However, at present, many vacuum devices including an optical system do not satisfy such a condition. For example, in the fields of medicine and biotechnology, which have been rapidly advancing in recent years, the resolution is higher than that of a microscope using ordinary visible light (λ = about 400 nm to 800 nm), and a living sample (hereinafter referred to as a biological sample), For example, cells, bacteria,
As a high-resolution microscope capable of clearly observing sperm, chromosomes, mitochondria, flagella, etc., an X-ray microscope using soft X-rays with a wavelength λ = 2 to 5 nm instead of visible light has been studied. Is also being developed.

For example, FIG. 4 shows a simple structure and optical system of such an X-ray microscope. In FIG. 4, the X-rays emitted from the X-ray generator 1 are condensed by the X-ray illumination optical system 2 and irradiated on the sample capsule 3. The X-ray transmitted through the sample capsule 3 forms an image of the sample on the X-ray imaging device 5 by the X-ray magnifying optical system 4. X-ray generator 1
The optical path length from to the X-ray imaging device 5 is, for example, about 2 m. Further, 6 is a vacuum exhaust container, and 7 is a vacuuming device for making the inside of this container a vacuum.

Recently, in order to improve the resolution of the optical system which is limited by the diffraction limit with the miniaturization of semiconductor integrated circuit elements, X rays having a wavelength shorter than that of ultraviolet rays have been used in place of conventional ultraviolet rays. Projection lithography technology has been developed.

For example, as shown in FIG. 5, an X-ray generator 1, an X-ray illumination optical system 2, a mask 8, a projection optical system 9, a wafer 10, and a vacuum exhaust container 6 for holding them in a vacuum atmosphere. And a device 7 for evacuating the inside of the container.

A vacuum exhaust system including such an optical system does not necessarily have to perform differential exhaust. In a vacuum device such as an X-ray microscope, the sample chamber may be set to a medium-high vacuum to reduce the absorption of X-rays, but in order to minimize the influence on the background pressure of the detection system chamber, or Differential evacuation must be provided when the detector itself (eg, Micro Channel Plate: MCP) only functions in high vacuum conditions.
The same can be said for the projection lithography system, which is an ultra-high / high-vacuum system, but in order to create the minimum necessary vacuum system that achieves the required vacuum level for each chamber, and the function of the system itself. As a result, differential pumping is required to improve throughput. However, the aforementioned SE
Since the light beam diameter is not small like M, the condition for using the orifice is not satisfied. Therefore, it is difficult to avoid such a configuration as much as possible or to reduce the conductance. Therefore, a large-scale vacuum system is configured to increase the pumping speed.

[0012]

As described above, in the vacuum device including the optical system, it is difficult to downsize and simplify the vacuum device having the luminous flux diameter to which the orifice is applied and the differential exhaust cannot be performed. Increasing throughput, which is part of the functionality, is also hindered.

Therefore, according to the present invention, in a vacuum device having a luminous flux diameter that cannot be differentially exhausted by an orifice, the vacuum device piping having a vacuum exhaust port that can reduce the conductance and increase the exhaust speed is small and simple. And a vacuum device using the same.

[0014]

In order to achieve the above object, a vacuum apparatus according to the present invention is a vacuum apparatus including an optical system, which is a low vacuum first vacuum container and a high vacuum second vacuum container. A vacuum container, a conduit for connecting between the vacuum containers, and an exhaust means for differentially exhausting between the vacuum containers are provided, and the conduit has a through hole for connecting between the vacuum containers. And a thin tube located inside the large inner diameter portion adjacent to the supporting portion and coaxially connected to the through hole, and having a large-diameter exhaust port connected to the large inner diameter portion at a side portion of the conduit. is there.

[0015]

In the vacuum apparatus including the optical system according to the present invention,
The conductance can be minimized by giving the thin tube a length that does not interfere with the specifications of the device.
However, if the gas is exhausted through the narrow tube, the conductance is too small, and the exhaust speed is also reduced. Therefore, in order not to reduce the exhaust speed, a vacuum exhaust port is separately provided. At this time, a thick pipe is arranged on the outer periphery of the thin pipe, and a vacuum exhaust port is drawn out from the thick pipe. Since the cross-sectional area of the thin tube is very small compared to the cross-sectional area of the thick tube, there is no effect on the exhaust speed. In this way, the conductance of the conduit through which the light flux passes is made small, and the space of the conduit is shared with the space of the vacuum exhaust port with a large conductance, which enables differential pumping and is compact and simplified. A vacuum device including an optical system using the vacuum pipe can be provided.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a sectional structure of a vacuum apparatus according to an embodiment of the present invention. It should be noted that members having the same structure and function as shown in FIGS. 2 and 3 to be described later are denoted by the same reference numerals, and description will be made centering on differences.

The vacuum apparatus of this embodiment will be described using an X-ray microscope as an example. In an X-ray microscope, the X
Perform in a vacuum atmosphere to avoid absorption of lines. At that time, the vacuum must be higher than at least 10 to ¹ [Pa]. Further, among X-ray detectors, there are some detectors such as those that are detected by MCP through a photoelectric conversion surface, and their performance cannot be utilized unless the degree of vacuum is higher than 10 to ⁵ [Pa]. . The X-ray microscope of FIG. 1 is an embodiment in which the vacuum system is made compact and simplified by the present invention. Although the device can be designed according to the degree of vacuum on the high vacuum side, the vacuum system can be downsized and simplified without constructing a large-scale vacuum system by dividing it into a low vacuum region and a high vacuum region.

That is, the vacuum apparatus of FIG. 1 comprises a sample vacuum container 6a, a detection system vacuum container 6b, and a conduit (pipe) 6c connecting these two vacuum containers to enable differential evacuation. An X-ray generator 1, an X-ray illumination optical system 2, a sample capsule 3, and an X-ray magnifying optical system 4 are arranged in the vacuum container 6a,
The X-ray imaging device 5 is arranged in the vacuum container 6b. Reference numeral 7a is a device for exhausting the vacuum container on the high vacuum side. Reference numeral 7b is a device for exhausting the vacuum container on the low vacuum side. The optical path length from the X-ray generator 1 to the X-ray imaging device 5 is determined by the optical system. For example, when using a Walter mirror, it is about 2 [m].

The material of the conduit 6c (including the thin tube 11) is a metal that is generally used as a vacuum material.
Stainless steel can be used because of its mechanical strength and chemical stability.

In the vacuum apparatus of FIG. 1, the sample vacuum container 6a is on the low vacuum side, the detection vacuum container 6b is on the high vacuum side, and differential evacuation is performed between the two. Differential evacuation does not separate spaces with different degrees of vacuum, but uses the pressure difference or raises the degree of vacuum only in the required space,
This is for improving the throughput and simplifying the configuration of the device. The exhaust devices 7a and 7b are responsible for exhausting the high vacuum side and the low vacuum side, respectively, and have the exhaust performance and the thin tube 11
The degree of vacuum in each vacuum container is determined by the conductance by The conduit 6c has a thin tube supporting portion (small inner diameter portion) having a thin through hole (conduction hole) 17 at one end of the thick tube.
16 and a thin tube 11 located at the center of a large inner diameter portion adjacent thereto and coaxially connected to the through hole 17 of the thin tube supporting portion 16. At the side of the conduit 6c, there is a vacuum exhaust port 12 connected to the internal space of the large inner diameter part, from which the exhaust device 7a exhausts the detection vacuum container 6b.

The thin tube 11 projects from the thin tube support portion 16 by making the passage between the vacuum vessels 6a and 6b longer so as to reduce the conductance, thereby reducing the pressure difference between the high vacuum side and the low vacuum side. This is to make it larger. Thin tube 1
1 may be projected to the sample vacuum container 6a side, but it is made to project only to the detection vacuum container 6b side in view of safety in handling and ease of manufacture in view of mechanical design.
For the same reason, the detection vacuum container 6b of the conduit 6c is also provided.
Is configured so as not to project beyond the flange surface 18 in contact with.

Further, in the conduit 6c, the thin tube 11 is configured to project from the thin tube support portion 16, so that the side surface of the conduit 6c (the large inner diameter from which the thin tube 11 projects is not increased without increasing the length of the entire conduit 6c. Vacuum exhaust port 1 in the space)
2 can be provided. To improve exhaust efficiency,
Although it is necessary to maximize the conductance between the detection vacuum container 6b and the exhaust device 7a, the vacuum exhaust port 12 provided in the conduit 6c in FIG. 1 can provide a sufficiently large conductance. The exhaust port 12 is used for the detection vacuum container 6
Although it may be provided in b, it is often not provided in the detection vacuum container 6b for various reasons. In such a case, the vacuum device of this embodiment is particularly useful.

As described above, by using the thin tube 11, it is possible to combine the conduit 6c for differential evacuation and the vacuum exhaust port 12 in a compact manner.
The size and simplification of the device can be realized.

Although the diameter of the X-ray beam is about 4 to 10 mm in the thin tube portion, if there is no manufacturing problem,
It is effective to make the thin tube in a shape that follows the light beam, that is, a tapered shape, in order to minimize the conductance,
This can increase the pressure difference across the conduit.

FIG. 2 shows the vacuum vessels 6a and 6b in FIG.
A thin tube supporting portion 16 which is equivalent to the conduit 6c between but which supports the thin tube 11 for reducing the conductance.
And a vacuum exhaust pipe 15 having a vacuum exhaust port 12 are detachably separated. As a result, differential evacuation can be performed in which the conductance can be adjusted simply by replacing the thin tube support portion 16 (thin tube 11).

In FIG. 3, as in FIG. 2, the thin tube supporting portion 16 and the vacuum exhaust tube 15 are made detachable, but an auxiliary adjusting mechanism 13 is further added to the thin tube 11 for adjusting conductance. It is a thing. Because of its function, the thin tube 11 is required to be thinner and thinner on the assumption that it does not block light. Therefore, the thin tube alone may be weak in strength. Therefore, an auxiliary adjusting mechanism 13 for reinforcing and adjusting the inclination is provided.

FIG. 6 is a plan view of the auxiliary adjusting mechanism 13 viewed from the detection vacuum container 6b side. This auxiliary adjustment mechanism 13
Is fixed to the thin tube supporting portion 16 and is screwed toward the center from three directions of the frame 13d extending along the thin tube 11 around the thin tube 11 and the outer periphery of the frame 13d having a cylindrical shape at least at its tip. 3 screws 13
a, 13b, 13c. By adjusting the advance / retreat of these screws, the inclination of the thin tube 11 located at the center can be finely adjusted. The thin tube 11 has a mechanical strength that is slightly flexible. By adjusting the screw, it becomes possible to adjust the optical axis that should pass through the thin tube 11 so as not to cut. This auxiliary adjustment mechanism 13
According to the above, since the thin tube 11 can be reinforced and the inclination can be adjusted,
The manufacturing accuracy required when the thin tube 11 is attached to the thin tube supporting portion 16 is reduced, and secular change can be prevented.

In the example of FIG. 3, a leak valve port 14 is further added. This is a manual or automatic vacuum valve. The vacuum container usually has a valve for returning to atmospheric pressure, and the inside of the vacuum container may be replaced with gas, and the leak valve port 14 serves such a role.

Although the embodiments of the X-ray microscope have been described above, such a differential evacuation system can also be applied to a vacuum apparatus for X-ray lithography.
It can also be applied to a vacuum device that includes differential pumping and does not include an optical system.

[0030]

As described above, in the vacuum apparatus including the optical system according to the present invention, by using the thin tube for reducing the conductance and the vacuum piping having the vacuum exhaust port having the large conductance, the luminous flux diameter can be reduced. The differential evacuation vacuum system can be incorporated into a vacuum device including an optical system having a relatively large size. Further, the size and size can be simplified without constructing a large-scale vacuum system. As a result, it is not necessary to arrange all of them in a high vacuum region, which leads to a reduction in cost and an improvement in operating rate as the exhaust time is shortened and the apparatus is simplified. Further, it is recognized that when there is a leak on the low vacuum side, the effect is also provided for protection on the high vacuum side. The present invention can be applied to all vacuum devices with differential evacuation.

[Brief description of drawings]

FIG. 1 is a diagram showing a cross-sectional structure of an embodiment of the present invention.

FIG. 2 is a diagram showing a cross-sectional structure of a modified example of the embodiment of FIG.

FIG. 3 is a diagram showing a cross-sectional structure of a modified example of the embodiment of FIG.

FIG. 4 is a diagram showing an outline of a conventional X-ray microscope.

FIG. 5: Conventional X-ray projection lithography apparatus

6 is an explanatory view of the auxiliary adjusting mechanism shown in FIG.

[Explanation of symbols]

 1 ... X-ray generator 2 ... X-ray illumination optical system 3 ... Sample capsule 4 ... X-ray magnifying optical system 5 ... X-ray imaging device 6 ... Vacuum exhaust container 6a ...・ Vacuum container for sample 6b ・ ・ ・ Vacuum container for detection system 6c ・ ・ ・ Conduit 7 ・ ・ ・ Device for evacuating 7a ・ ・ ・ Exhaust device on high vacuum side 7b ・ ・ ・ Exhaust device on low vacuum side 8 ・ ・ ・Mask 9 ... Projection optical system 10 ... Wafer 11 ... Capillary tube 12 ... Vacuum exhaust port 13 ... Auxiliary adjustment mechanism 14 ... Auxiliary port 15 ... Vacuum exhaust pipe 16 ... Capillary tube Support part 17 ... through hole

Claims (6)

[Claims] 1. A vacuum device including an optical system, comprising: a first vacuum container having a low vacuum, a second vacuum container having a high vacuum, a conduit for connecting between the vacuum containers, and a space between the vacuum containers. And an exhausting means for performing differential evacuation with the conduit, wherein the conduit has a support portion having a through hole for electrical connection between both vacuum vessels, and the through hole located in a large inner diameter portion adjacent to the support portion. A vacuum device comprising: a thin tube connected coaxially; and a large-diameter exhaust port connected to the large-inner-diameter portion on a side portion of the conduit. 2. The vacuum apparatus according to claim 1, wherein the tip end of the capillary in the conduit is located at the same position as or inside the end surface of the conduit. 3. The vacuum apparatus according to claim 1, wherein a thin tube support portion of the conduit to which the thin tube is connected and a large diameter portion having the vacuum exhaust port are detachably separated. . 4. The vacuum apparatus according to claim 3, further comprising an auxiliary adjusting mechanism that is fixed to the thin tube supporting portion and mechanically adjusts the inclination of the thin tube. 5. The vacuum apparatus according to claim 1, wherein the vacuum apparatus having the optical system is a vacuum apparatus having a luminous flux diameter that cannot be differentially exhausted by an orifice. 6. A vacuum apparatus including an optical system, comprising a low-vacuum vacuum container, a high-vacuum vacuum container, and a vacuum pipe for connecting between the two vacuum containers. A vacuum device characterized by having both a thin tube and a vacuum exhaust port for performing differential exhaust between containers.