JP7681503B2 - Cooling structure and device equipped with same - Google Patents

Description

The present invention relates to a cooling structure and a device equipped with the same, and in particular to a technique for thermally connecting a non-rotating member and a rotating member.

A focused ion beam processing device is a device that processes a sample by irradiating the sample with a focused ion beam (FIB). Hereinafter, the focused ion beam processing device will be referred to as an FIB processing device. FIB devices equipped with a scanning electron microscope (SEM) are also known.

The FIB processing device has a sample stage that holds a sample and changes the position and attitude of the sample. For example, the sample stage has a tilt mechanism, an elevation mechanism (Z mechanism), a slide mechanism (XY mechanism), a rotation mechanism, a sample table, etc. The sample is held by the sample table. Specifically, the sample or a sample stage holding the sample is attached to the sample table. The sample table performs tilt movement, elevation movement, slide movement, and rotation movement. The sample table is a rotating member when viewed from the member that rotatably supports it. The position and attitude of the sample table change significantly during the sample processing process.

In some cases, a cooled sample is processed in an FIB processing device. One such sample is a biological sample. In order to keep the sample cooled, the sample table holding the sample must be cooled. For example, a cooling device may be provided and connected to the sample table with a flexible heat-conducting member (see Patent Document 1 and Non-Patent Document 1). However, when adopting this configuration, the overall length of the heat-conducting member must be made considerably long so that large changes in the position and attitude of the sample table can be tolerated, and the heat-conducting member must be positioned so that it does not interfere with sample processing or observation even when the sample table rotates. Patent Document 2 discloses a multi-axis stage with roller bearings. The roller bearings have multiple rollers that exert a heat-conducting effect.

Stage cooling is also required in sample processing devices other than FIB processing devices and sample observation devices such as scanning electron microscopes. Note that Patent Document 1, Patent Document 2, and Non-Patent Document 1 do not disclose a flexible heat conductive member disposed in the gap between the non-rotating member and the rotating member.

Japanese Unexamined Patent Publication No. 2-144843 Patent No. 641877

Japan Institute of Invention and Innovation, Technical Report No. 2009-503261

In a sample processing device or a sample observation device, the sample stage generally has a rotating member that functions as a sample table. Assuming that a non-rotating member arranged near the rotating member is cooled, it is required to thermally connect the non-rotating member and the rotating member without interfering with the rotational motion of the rotating member.

The object of the present invention is to generate good thermal conduction between a non-rotating member and a rotating member. Alternatively, the object of the present invention is to effectively cool a second member through a first member in a sample stage having a first member and a second member that rotate relative to one another.

The cooling structure of the present invention includes a non-rotating member having a non-rotating surface perpendicular to the central axis of rotation and thermally connected to a cooling source, a rotating member having a rotating surface perpendicular to the central axis of rotation and facing the non-rotating surface across a gap, and holding a sample, and a thermal link unit having at least one thermal link arranged in the gap, wherein the thermal link is composed of a non-rotating end fixed to the non-rotating surface, a rotating end fixed to the rotating surface, and a flexible member between the non-rotating end and the rotating end , and includes a main body having a curved, band-like form in an unfolded state , the main body having a U-shaped curved portion curved from on the non-rotating surface to on the rotating surface, a first flat portion between the non-rotating end and the curved portion, and a second flat portion between the rotating end and the curved portion, wherein each of the first flat portion and the second flat portion is curved along a circumferential direction when viewed from the direction of the central axis of rotation .

The apparatus according to the present invention is an apparatus for performing at least one of sample processing and sample observation, and includes a sample stage provided within a sample chamber and having a cooling structure, a cooling source, a cooling member fixed within the sample chamber and thermally connected to the cooling source, and a heat conductive member that thermally connects the cooling member and the sample stage while allowing changes in the position and attitude of the sample stage, and the cooling structure includes a first member having a first surface perpendicular to a central axis of rotation and thermally connected to the heat conductive member, a second member having a second surface perpendicular to the central axis of rotation and facing the first surface across a gap, and rotating relatively to the first member, and a second member disposed in the gap and connecting the first member and the and a thermal link section having at least one thermal link thermally connecting the thermal link to a second member, the thermal link being composed of a first end fixed to the first surface, a second end fixed to the second surface, and a flexible member provided between the first end and the second end, and a main body having a curved, band-like form in an unfolded state , the main body having a U-shaped curved portion curved from the first surface to the second surface, a first flat portion between the first end and the curved portion, and a second flat portion between the second end and the curved portion, each of the first flat portion and the second flat portion being curved along a circumferential direction when viewed from the direction of the rotation center axis .

According to the present invention, it is possible to generate good thermal conduction between a non-rotating member and a rotating member. Alternatively, according to the present invention, it is possible to effectively cool a second member through a first member in a sample stage.

1 is a cross-sectional view showing a sample processing device according to an embodiment. FIG. 2 is an enlarged cross-sectional view showing a cooling structure according to an embodiment. FIG. 2 is a perspective view showing an arrangement of a thermal link according to the embodiment; FIG. 2 is a plan view showing a deployed state of the thermal link according to the embodiment. FIG. 4 is a plan view showing a thermal link portion according to the embodiment. 1 is a perspective view showing a specific example of a cooling structure according to an embodiment; 13 is a plan view showing a modified example of the thermal link portion. FIG.

The following describes the embodiment with reference to the drawings.

(1) Overview of the embodiment The cooling structure according to the embodiment includes a non-rotating member, a rotating member, and a thermal link. The non-rotating member has a non-rotating surface perpendicular to the central axis of rotation, and is thermally connected to a cooling source. The rotating member has a rotating surface perpendicular to the central axis of rotation and facing the non-rotating surface across a gap, and is a member for holding a sample. The thermal link portion includes at least one thermal link disposed in the gap. The thermal link includes a non-rotating end portion fixed to the non-rotating surface, a rotating end portion fixed to the rotating surface, and a main body. The main body is formed of a flexible member between the non-rotating end portion and the rotating end portion. The main body has a U-shaped curved portion curved from the non-rotating surface to the rotating surface. The main body is also curved along the circumferential direction when viewed from the direction of the central axis of rotation.

According to the above configuration, the non-rotating member and the rotating member are thermally connected by the thermal link. This cools the rotating member, and the sample held by the rotating member is cooled. In the thermal link, when the rotating member rotates, the rotating end moves in the circumferential direction, and the curved portion moves in the circumferential direction accordingly. In this way, when the rotating member rotates, the shape of the main body of the thermal link naturally changes, so the thermal link does not interfere with the rotational movement of the rotating member.

The thermal link is placed in the gap between the non-rotating member and the rotating member, so there is no need to secure a large space around the rotating member for the thermal link. In an embodiment, a flexible thermally conductive member is connected directly or indirectly to the non-rotating member. The thermally conductive member is easily positioned because it does not need to take into account rotational motion. In an embodiment, a portion of the body of the thermal link contacts the non-rotating surface, and another portion contacts the rotating surface. This allows for better thermal conduction between the non-rotating member and the rotating member.

In an embodiment, when the rotation angle of the rotating member is 0 degrees, the rotating end overlaps the non-rotating end when viewed from the direction of the central axis of rotation. With this configuration, the maximum rotation angle in the forward rotation direction and the maximum rotation angle in the reverse rotation direction are the same.

In an embodiment, the main body has a curved band-like shape in its deployed state. The main body has a first flat portion and a second flat portion. The first flat portion is a portion between the non-rotating end and the curved portion that extends parallel to the non-rotating surface. The second flat portion is a portion between the rotating end and the curved portion that extends parallel to the rotating surface. The first flat portion contacts the non-rotating surface, and the second flat portion contacts the rotating surface. In an embodiment, the length of the first flat portion and the length of the second flat portion change depending on the direction and amount of rotation of the rotating member.

In an embodiment, the thermal link portion includes a plurality of thermal links arranged circumferentially within the gap. Each thermal link has a non-rotating end, a rotating end, and a body. This configuration can improve thermal conduction between the non-rotating member and the rotating member.

In an embodiment, the multiple thermal links are aligned in the same direction along the circumferential direction. This configuration makes it easier to uniformly cool the rotating member. In an embodiment, the main body is composed of multiple sheets stacked in an unfastened state. This configuration reduces the load generated when the rotating member rotates. In addition, since none of the sheets are exposed except for the two exposed sheets on both sides, the effects of radiation are less likely to occur.

The device according to the embodiment is a device for performing at least one of sample processing and sample observation. The device has a sample stage, a cooling source, a cooling member, and a heat conductive member. The sample stage is provided in a sample chamber and has a cooling structure. The cooling member is fixed in the sample chamber and thermally connected to the cooling source. The heat conductive member thermally connects the cooling member and the sample stage while allowing changes in the position and attitude of the sample stage. The cooling structure has a first member, a second member, and a heat link unit. The first member is a member having a first surface perpendicular to the central axis of rotation and thermally connected to the heat conductive member. The second member is a member having a second surface perpendicular to the central axis of rotation and facing the first surface across a gap, and rotating relative to the first member. The heat link unit has at least one heat link disposed in the gap and thermally connecting the first member and the second member. The heat link has a first end, a second end, and a main body. The first end is fixed to the first surface. The second end is fixed to the second surface. The main body is made of a flexible member provided between the first end and the second end. The main body has a U-shaped curved portion that curves from the first surface to the second surface. The main body is also curved along the circumferential direction when viewed from the direction of the central axis of rotation.

The first member is, for example, a non-rotating member. The second member is, for example, a rotating member. A specific example is a sample table. When a heat conductive member is connected to the non-rotating member, it is not necessary to consider the rotational motion of the rotating member when arranging the heat conductive member. It is not necessary to consider any motion other than the rotational motion when arranging the thermal link. The above cooling structure may be incorporated into devices other than the sample processing device and the sample observation device.

(2) Details of the embodiment Fig. 1 shows a cross section of a sample processing device 10 according to the embodiment. The x direction is the first horizontal direction, and the z direction is the vertical direction. The direction perpendicular to the x direction and the z direction is the y direction as the second horizontal direction. The y direction is the direction penetrating the page in Fig. 1.

Specifically, the sample processing device 10 is an FIB/SEM processing and observation device. That is, the sample processing device 10 has the function of processing a sample using a focused ion beam (FIB) and the function of observing the sample by scanning with an electron beam.

The sample processing device 10 is equipped with an SEM lens barrel 12 and an FIB lens barrel. The FIB lens barrel is not shown in FIG. 1. An electron beam 18 is generated in the SEM lens barrel 12. An FIB is generated in the FIB lens barrel. A housing 13 is provided below the SEM lens barrel 12, and its interior is a sample chamber 14.

A part of the objective lens 16 is inserted in the sample chamber 14, and a sample stage 20 is provided in the sample chamber 14. The sample stage 20 has a tilt function, an elevation mechanism (Z mechanism), a slide mechanism (XY mechanism), a rotation mechanism, etc. The sample table 36 in the sample stage 20 performs tilt movement, elevation movement, slide movement, and rotation movement. In FIG. 1, reference numeral 24 indicates the tilt axis (tilt central axis), and reference numeral 22 indicates the tilt movement around the tilt axis. Reference numeral 26 indicates the elevation movement. Reference numeral 28 indicates the slide movement. Reference numeral 32 indicates the rotation axis (rotation central axis), and reference numeral 30 indicates the rotation movement around the rotation axis.

The sample table 36 has a generally disk-like shape. The sample 40 is held by the sample table 36. Specifically, the sample 40 is attached to the sample table 36, or a sample stage 38 holding the sample 40 is attached to the sample table 36. Reference numeral 34 denotes a rotating body including the sample table 36. The rotating body 34 has a shaft member connected to the sample table 36, a rotating base that supports the shaft member, etc.

A dish-shaped frame 42 is provided below the sample table 36. The frame 42 is a non-rotating member that functions as a floating base. An opening is formed in the center of the frame 42, and the shaft member passes through the opening without contact.

One end of the L-shaped heat conducting member 44 is connected to the frame 42. A support member 48 supports the heat conducting member 44. The heat conducting member 44 and the frame 42 are made of, for example, a metal with high thermal conductivity. All or part of the support member 48 is made of a material with low thermal conductivity, i.e., a thermal insulating material.

The sample processing device 10 has a cooling facility 50. In the illustrated configuration example, the cooling facility 50 includes a refrigerant tank 52, a connecting plate 54, a cooling member 56, and a flexible heat-conducting member 58. The refrigerant tank 52 contains, for example, liquid nitrogen as a refrigerant. The cooling member 56 is disposed in the sample chamber 14, and is, for example, an annular member provided around the objective lens 16. A connecting plate 54 is provided to thermally connect the refrigerant tank 52 and the cooling member 56. The connecting plate 54 and the cooling member 56 are, for example, made of a metal having high thermal conductivity. The heat-conducting member 58 is, for example, made of a flexible flat braided wire having high thermal conductivity. The heat-conducting member 58 has sufficient slack to allow the tilting, lifting, and sliding movements of the sample stage 20.

The upper end of the heat conducting member 58 is connected to the cooling member 56. The lower end of the heat conducting member 58 is connected to one end of the heat conducting member 44. The other end of the heat conducting member 44 is connected to the frame 42. The refrigerant tank 52, which is the cooling source, is thermally connected to the frame 42 via multiple heat conducting members, and cold is transported to the frame 42. The frame 42 is in a cooling state.

A thermal link unit 60 is provided to thermally connect the frame 42 and the sample table 36 without interfering with the rotational movement of the sample table 36. The thermal link unit 60 is disposed in a gap G formed between the frame 42 and the sample table 36. The frame 42, the sample table 36, and the thermal link unit 60 form a cooling structure.

Figure 2 shows a cross section of the cooling structure. The sample stage 38 is attached to the upper surface (surface on the sample side) 103 of the sample table 36, and the sample stage 38 holds the sample 40. The frame 42 is composed of a frame body 42A as a disk and a cylindrical side wall 42B. The space between the upper surface (surface on the sample side) 100 of the frame body 42A and the lower surface (surface on the non-sample side) of the sample table 36 is the gap G. The first thermal link 62-1 and the second thermal link 62-2 constituting the thermal link section 60 are provided in the gap G. The first thermal link 62-1 and the second thermal link 62-2 are members that thermally connect the frame 42 and the sample table 36 while allowing the sample table 36 to rotate. The first thermal link 62-1 and the second thermal link 62-2 have the same shape as each other.

Figure 3 shows the thermal link 62. The thermal link 62 has an end 66 fixed to the upper surface (non-rotating surface) of the frame body, an end 68 fixed to the lower surface (rotating surface) of the sample plate, and a body 64 between the two ends 66, 68. The end 66 is the non-rotating end, and the end 68 is the rotating end. The body 64 is a sheet stack consisting of, for example, 100 to 200 metal sheets. The sheets are not fastened to each other, and the body 64 as a whole is flexible. Each sheet is, for example, silver foil. The thickness of each sheet is, for example, 0.005 mm.

Ends 66 and 68 hold one end and the other end of the sheet stack. Ends 66, 68 are made of, for example, a metal with high thermal conductivity (such as copper). End 66 is fixed to the frame body by two screws, and end 68 is also fixed to the sample table by two screws.

The main body 64 has a U-shaped curved portion 64a that curves from the non-rotating surface of the frame main body to the rotating surface of the sample table. In other words, when viewed from a direction perpendicular to the central axis of rotation, it has a curved portion. On the other hand, when viewed from the direction of the central axis of rotation, the main body 64 has an arc-shaped shape that curves in the circumferential direction around the central axis of rotation.

The first flat portion 64b is between the curved portion 64a and the end 66, and the second flat portion 64c is between the curved portion 64a and the end 68. The first flat portion 64b and the second flat portion 64c extend in a direction perpendicular to the central axis of rotation and are parallel to each surface of the frame body and each surface of the sample plate.

When the sample plate rotates, the end 68 moves in an arc. Accordingly, the position of the curved portion 64a in the main body 64 changes. In other words, the length of the first flat portion 64b and the length of the second flat portion 64c change. For example, when the end 68 rotates in the +θ direction, the curved portion also rotates in the +θ direction. In the process, the length of the first flat portion 64b becomes shorter, and the length of the second flat portion 64c becomes longer. Conversely, when the end 68 rotates in the -θ direction, the curved portion also rotates in the -θ direction. In the process, the length of the first flat portion 64b becomes longer, and the length of the second flat portion 64c becomes shorter.

As shown in Figure 3, when viewed from the direction of the central axis of rotation, the state in which end 66 and end 68 overlap is the state of a rotation angle of 0 degrees. Using this as a reference, 180 degrees of rotation is permitted in the +θ direction, and 180 degrees of rotation is also permitted in the -θ direction. The angular range over which the sample table can rotate is 360 degrees. The length of main body 64 and the height of the gap are determined so that such rotation is permitted. For example, the height of the gap is set within the range of 5 to 12 mm. The length of main body 64 (the length of the arc-shaped center line) is set within the range of 500 to 900 mm.

The bottom surface A of the first flat portion 64b contacts the frame body, and the top surface B of the second flat portion 64c typically contacts the sample table. Such contact contributes to improving thermal conductivity. The bottom surface A and the top surface B are the same outer surface of the body 64.

Figure 4 shows the thermal link 62A in an expanded state. The main body 64 has an arc shape. Ends 66, 68 are provided at both ends of the main body 64. The radius of curvature of the inner side and the outer side of the main body 64 are determined according to the installation condition of the main body 64. Reference numeral 64a indicates a curved portion. As indicated by reference numeral 72, the direction and amount of rotation of the curved portion 64a are determined according to the direction and amount of rotation of the sample table.

Figure 5 shows the top surface of the thermal link section 60. The sample table is not shown in Figure 5. The thermal link section 60 is composed of a first thermal link 62-1 and a second thermal link 62-2. The orientation of the first thermal link 62-1 and the orientation of the second thermal link 62-2 are the same. That is, the terminal 68-1 of the first thermal link 62-1 and the curved portion 64a-2 of the second thermal link 62-2 are adjacent to each other, and the terminal 68-2 of the second thermal link 62-2 and the curved portion 64a-1 of the first thermal link 62-1 are adjacent to each other.

This configuration makes it possible to suppress the temperature gradient in the sample table, i.e., to uniformly cool the entire sample table. As described below, the thermal link unit 60 may be configured with three or more thermal links.

Figure 6 shows a specific example of the cooling structure. A sample stage 38 is attached to the upper surface of a circular sample table 36. A sample cassette 74 containing a sample is held by the sample stage 38. A frame 42 is provided below the sample table 36. A gap G is formed between the frame body 42A and the sample table 36, and a thermal link unit 60 is disposed in this gap G. The thermal link unit 60 is composed of two thermal links 62-1, 62-2 disposed in the circumferential direction around the central axis of rotation.

In the illustrated example, the heat conduction member 58 connected to the L-shaped heat conduction member 44 is composed of two flat braided wires.

Figure 7 shows a modified example of the thermal link section. The thermal link section 76 is composed of three thermal links 78-1, 78-2, and 78-3 arranged in the circumferential direction around the central axis of rotation. The three thermal links 78-1, 78-2, and 78-3 are aligned in the same direction. For example, between two adjacent thermal links 78-1 and 78-2, the curved end 80 of the thermal link 78-1 and the terminal 82 of the thermal link 78-2 are close to each other but not in contact with each other.

According to the above embodiment, the thermal link unit thermally connects the frame (non-rotating member) and the sample table (rotating member). This cools the sample table, and the sample held on the sample table. When the sample table rotates, the shape of the body in each thermal link changes naturally, so that each thermal link does not interfere with the rotational movement of the sample table. Each thermal link is disposed in a small gap between the frame and the sample table. Therefore, there is no need to secure a large space around the sample table for installing the thermal link.

In the above embodiment, the flexible heat conduction member that allows the tilt, lift and slide movements of the sample table is separated from the flexible heat conduction member that allows the rotational movement of the sample table. This improves the efficiency of heat conduction compared to a case where a long flexible heat conduction member that allows all movements is provided, and also makes it easy to avoid the problem of the flexible heat conduction member coming into contact with structures in the sample chamber.

20 sample stage, 36 sample table, 40 sample, 42 frame, 60 thermal link portion, 50 cooling equipment, 62, 62-1, 62-2 thermal links, 66, 68 end portion, 64 main body, 64a curved portion, 64b first flat portion, 64c second flat portion.

Claims (9)

a non-rotating member having a non-rotating surface perpendicular to the central axis of rotation and thermally connected to a cooling source;
a rotating member having a rotating surface that is perpendicular to the central axis of rotation and faces the non-rotating surface across a gap, the rotating member holding a sample;
a thermal link portion having at least one thermal link disposed in the gap;
Including,
The thermal link is
a non-rotating end portion fixed to the non-rotating surface;
A rotating end portion fixed to the rotating surface;
a main body formed of a flexible member between the non-rotating end and the rotating end , the main body having a curved band-like shape in an unfolded state, the main body having a U-shaped curved portion that curves from the non-rotating surface to the rotating surface, a first flat portion between the non-rotating end and the curved portion, and a second flat portion between the rotating end and the curved portion;
Including,
A cooling structure, characterized in that each of the first flat portion and the second flat portion is curved along a circumferential direction when viewed from a direction of the central axis of rotation. The cooling structure according to claim 1,
When the rotating member rotates, the rotating end moves along the circumferential direction, and the curved portion moves along the circumferential direction accordingly.
A cooling structure characterized by: The cooling structure according to claim 2,
When the rotation angle of the rotating member is 0 degrees, the rotating end portion overlaps with the non-rotating end portion when viewed from the direction of the rotation central axis.
A cooling structure characterized by: The cooling structure according to claim 1 ,
The body includes :
a first flat portion between the non-rotating end and the curved portion, the first flat portion extending parallel to the non-rotating surface;
a second flat portion extending parallel to the plane of rotation between the end of rotation and the curved portion;
Including,
the first flat portion contacts the non-rotating surface;
the second flat portion contacts the rotating surface;
A cooling structure characterized by: The cooling structure according to claim 4,
A length of the first flat portion and a length of the second flat portion change depending on a rotation direction and an amount of rotation of the rotating member.
A cooling structure characterized by: The cooling structure according to claim 1,
the thermal link unit includes a plurality of thermal links aligned along the circumferential direction within the gap,
each said thermal link having said non-rotating end, said rotating end, and said body;
A cooling structure characterized by: The cooling structure according to claim 6,
The plurality of thermal links are arranged in the same direction along the circumferential direction.
A cooling structure characterized by: The cooling structure according to claim 1,
The main body is composed of a plurality of sheets stacked in an unfastened state.
A cooling structure characterized by: An apparatus for performing at least one of sample processing and sample observation, comprising:
a sample stage provided in the sample chamber and having a cooling structure;
A cooling source;
a cooling member fixed within the sample chamber and thermally connected to the cooling source;
a heat conductive member that thermally connects the cooling member and the sample stage while allowing changes in the position and attitude of the sample stage;
Including,
The cooling structure includes:
a first member having a first surface perpendicular to a central axis of rotation and thermally connected to the heat conducting member;
a second member having a second surface that is perpendicular to the central axis of rotation and faces the first surface across a gap, the second member rotating relatively to the first member;
a thermal link unit having at least one thermal link disposed in the gap and thermally connecting the first member and the second member;
Including,
The thermal link is
a first end secured to the first surface;
a second end secured to the second surface;
a main body that is configured with a flexible member provided between the first end and the second end , and has a curved band-like shape in an unfolded state , the main body having a U-shaped curved portion that curves from on the first surface to on the second surface , a first flat portion between the first end and the curved portion, and a second flat portion between the second end and the curved portion;
Including,
An apparatus equipped with a cooling structure, characterized in that each of the first flat portion and the second flat portion is curved along a circumferential direction when viewed from the direction of the central axis of rotation.