JP2839693B2 - Magnetic field type lenses in electron microscopes, etc. - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magnetic field lens used for an electron microscope.

2. Description of the Related Art Conventionally, a magnetic field type lens used as a focusing lens or an objective lens of an electron microscope or the like has a coil formed by turning a linear conductor whose surface is covered with an insulating coating in an annular shape into an annular yoke. It is formed by joining or by directly turning a wire on the middle yoke (inner cylinder) of the annular yoke.

FIG. 6 shows the configuration of an objective lens used in a transmission electron microscope. In FIG. 6, 1 is a yoke formed in an annular shape, 2 is a coil formed by turning a conducting wire in an annular shape, 3
Reference numerals a and 3b denote annular cooling blocks in which pipes 4 for circulating cooling water are embedded. In the yoke gap, an upper magnetic pole piece 5a and a lower magnetic pole piece 5b for converging a magnetic field formed in the portion are provided.
The sample S mounted on the tip of the sample holder 6 is introduced between the magnetic pole pieces from outside the lens barrel (not shown) to the electron beam path (optical axis Z) in the objective lens. In the so-called side entry type electron microscope described above,
The position of the coil 2 is lowered to provide a space 7 inside the objective lens, and a sample is introduced from outside the lens barrel through the space. The space also has a direction perpendicular to the plane of FIG. Along with the objective lens aperture 8 being inserted, a detector 9 for detecting various information emitted from the sample, for example, secondary electrons and X-rays, is introduced toward the sample.
The space is also used when an ion gun or a vapor deposition device is arranged near the sample in order to perform a surface treatment on the introduced sample.

[Problems to be Solved by the Invention] As described above, the position of the coil is lowered to make space in the objective lens, or the coil is divided and divided as in the other type of objective lens shown in FIG. Place and coil
When a space is provided between 2a and 2b, the shape of the yoke is inevitably elongated in the optical axis Z direction. If the yoke is simply extended, the magnetic flux of the middle yoke (the inner cylinder 1a of the annular yoke) increases. Therefore, unless the thickness of the yoke is increased to increase the cross-sectional area, the magnetic flux density of the magnetic lens decreases. ,
This decrease in magnetic flux density can be prevented by the following two methods. One is to prevent the magnetic flux density from decreasing by improving the magnetic circuit such as increasing the thickness of the above-mentioned middle yoke (the inner cylinder 1a of the annular yoke), and the other is to increase the ampere-turn of the coil. That is. However, when the middle yoke is made thicker, both the inner diameter and the outer diameter of the annular coil are enlarged, so that the diameter of the entire objective lens becomes large, and more power is required to obtain the same magnetic field. . Also, when the number of turns of the coil is increased while maintaining the above-mentioned space, the outer diameter of the annular coil also increases. On the other hand, in order to prevent the diameter of the objective lens from expanding, it is only necessary to turn the coil high in the optical axis direction, but even if the objective lens is extended in the optical axis direction while maintaining the above-mentioned space, it is not Since the length limit is determined by the optical conditions of the focusing lens and the intermediate lens arranged above and below the objective lens, the length cannot be extremely long.

Further, since a coil used for an objective lens or the like as described above generally generates a large amount of heat, the coil is cooled with water to dissipate heat so as to obtain a thermal sufficiency of the lens. Therefore, if the amount of current supplied to the coil is simply increased to prevent the magnetic flux density from lowering, the amount of heat generated increases and the stability of the lens is impaired.

The present invention has been made in consideration of the above-described problems, and has an electron microscope that can form a space for introducing a sample, a detector, and the like into a yoke and has good lens stability even in a small yoke shape. It is an object of the present invention to provide a magnetic field type lens in such as.

[Means for Solving the Problems] A magnetic field type lens in an electron microscope or the like according to the first aspect of the present invention forms a magnetic field type lens by fitting a coil formed by turning a band-shaped conductor in an annular shape into an annular yoke. Along with
The coil is provided with a hole or notch reaching from the outer periphery to the inner periphery to form a space in the annular yoke.

Further, the magnetic field type lens in the electron microscope or the like according to the second invention is a magnetic field type lens formed by fitting a coil formed by turning a band-shaped conductor in an annular shape into an annular yoke. In the whole section or the partial section from the winding start to the winding end, the coil is turned while shifting the winding position in the width direction of the band to form a space between the coil upper or lower surface and the yoke. And

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is an apparatus configuration diagram for explaining one embodiment of the first present invention. In the embodiment shown in FIG.
The same components as those in the drawings are denoted by the same reference numerals and description thereof is omitted. The embodiment shown in FIG. 1 is different from the conventional example in that an annular coil 11 formed by turning a thin strip-shaped conductor 10 covered with an insulating film is fitted into an annular yoke 1 to form a magnetic field type. The point is that a hole is formed in the coil 11 so as to penetrate the coil 11 from the outer periphery to the inner periphery, and a space for introducing the sample holder 6 and the detector 9 is formed in the coil 11.

In a coil formed by turning such a band-shaped conductor 10, if the hole has a diameter smaller than the width of the band 10, even if the hole penetrates from the outer periphery to the inner periphery of the coil, the current flowing through the coil is Even if a plurality of sample holders, aperture plates, detectors, etc. are introduced, the required space can be obtained by providing a plurality of through holes 12 for the coil radially with respect to the optical axis Z. Can be obtained.

Therefore, since it is not necessary to extend the yoke to lower the position of the coil and form a space, it is possible to reduce the size of the objective lens.

In addition, since the coil is formed by a strip-shaped conductor, the contact area between the strips is larger than that of a coil formed by turning conventional wires each having a circular or square cross section, so that heat transfer is achieved. Efficiency increases, and even when the coil is fitted to the yoke, the coil end and the cooling block or the coil side surface and the yoke come into close contact, further improving the heat dissipation or cooling efficiency of the coil and stably operating the lens. Can be done. Further, since the cooling efficiency is improved, the lens current can be increased as compared with the related art, so that the performance of the lens can be improved even in a small yoke shape.

FIG. 2 is a view for explaining a second embodiment of the magnetic field type lens according to the first invention. In the embodiment shown in FIG. 2, a coil 11 formed by turning a strip-shaped conductor 10 is fitted into the space 7 of the conventional objective lens shown in FIG. By providing a hole 12 penetrating to the inner periphery,
The point is that a space for introducing the sample holder 6 and the detector 9 is formed in the coil. As a result, the coil can be arranged in the space provided in the conventional yoke without hindering the introduction of the sample or the like, so that the total number of turns of the coil can be increased.

Here, the coil 2 formed by turning the wire and the coil 11 formed by turning the strip-shaped conductor may be electrically connected to form an integrated coil, or the lens current may be separately supplied. The configuration may be as follows.

FIG. 3 is a view for explaining a third embodiment of the magnetic field type lens according to the first present invention, and FIG. 4 is a view A of FIG.
FIG. In the embodiment shown in FIGS. 3 and 4, coils 11a, 11b, 11
Notches (grooves) 13a, in which a cross-sectional shape is a semicircle in opposite portions of the end faces of the coils 11c and 11d.
13b is provided so as to reach from the outer peripheral portion to the inner peripheral portion to form a space between the coils. When the notches are provided in the two coils to form a space as described above, more conductor portions that are not cut and left can be obtained as compared with the case where holes are provided in the one-stage strip-shaped conductor. Therefore, the electric resistance of the remaining conductor portion is reduced, so that heat generation in the portion can be suppressed.

FIG. 5 is a view for explaining an embodiment of the magnetic field type lens according to the second invention.

In the embodiment shown in FIG. 5, the point that a coil formed by turning a band-shaped conductor in an annular shape is fitted into an annular yoke to form a magnetic field lens is the same as in the first embodiment of the present invention.
In the present invention, as can be seen from the figure, the coils 14a, 14b, 14c, which are turned while shifting the winding position in the width direction of the band from the winding start A to the winding end B of the band, are placed in the annular yoke. And the upper surface of the coil 14c and the yoke 1
To form a space between them. in this way,
If the winding position of the band-shaped conductor 10 is turned in an annular shape while shifting the winding position in the axial direction of the band, the cross-sectional shape of the coil can be easily changed as compared with a conventionally generally used electric wire,
The space formed between the upper surface of the coil and the yoke can be obtained as a free shape. Therefore, the detector 9 is located at a position where the sample S is obliquely viewed from above as shown in FIG.
Processing equipment for vapor deposition or etching (not shown)
When it is necessary to dispose the coil, it is possible to easily secure the introduction path that is hindered by the coil. In the embodiment shown in FIG. 5, a notch (groove) 15 having a semicircular cross section is provided on the upper surface of the coil from the outer peripheral portion to the inner peripheral portion.

In the first and second inventions described above, the holes or cutouts formed in the strip-shaped conductor can be easily provided by mechanical cutting or electric field processing. Since the part is lost, it is necessary to treat the part by chemical etching or the like to re-attach the insulating film to achieve electrical insulation between adjacent conductors.

The above-described embodiment is merely an embodiment of the present invention, and the present invention can be implemented with various modifications. For example, in the above-described embodiment, the case where the magnetic field type lens according to the present invention is applied to the objective lens of the transmission electron microscope has been described. However, the present invention similarly applies to the case where a stop is inserted into a focusing lens or the like of an electron microscope. Applied. Further, in the above-described embodiment, the hole or the notch formed in the coil is formed in a circular or semicircular shape, but the shape of the hole or the notch may be any shape. Further, the hole or notch is provided with a uniform size from the outer peripheral portion to the inner peripheral portion of the coil, but the size of the hole or notch is gradually reduced from the outer peripheral portion to the inner peripheral portion of the coil. May be provided.

[Effects of the Invention] As is apparent from the above description, according to the first aspect of the present invention, a coil formed by turning a band-shaped conductor in an annular shape is fitted into an annular yoke to form a magnetic field lens. By providing a hole or notch in the coil from the outer periphery to the inner periphery to form a space in the annular yoke, a space necessary for introduction such as a sample holder, an aperture plate, and a detector is formed by the hole or notch. Since it can be obtained by the notch, it is not necessary to extend the yoke to lower the position of the coil or to divide the coil to form a space for introducing a sample, a detector, and the like into the yoke. In addition, since the coil is formed of a strip conductor, the contact state between the strip conductors is better than that of a conventional coil formed by turning wires having a circular or square cross section, thereby improving heat transfer efficiency. When the coil is fitted to the yoke, the coil end and the cooling block or yoke come into close contact with each other, further improving the heat radiation or cooling efficiency of the coil. A space for introducing a sample, a detector, and the like can be formed therein, and a magnetic field type lens in an electron microscope or the like having good lens stability can be obtained.

According to a second aspect of the present invention, there is provided a magnetic field lens formed by fitting a coil formed by turning a band-shaped conductor in an annular shape into an annular yoke. In the entire section or partial section up to this point, the coil is turned while shifting the winding position in the width direction of the band to form a space between the coil upper surface or lower surface and the yoke. It is possible to obtain the space formed between them as a free shape, and the coil blocks the introduction path for introducing a detector or a processing device for vapor deposition or etching at a position where the sample can be seen from obliquely above or below. Can be secured without any problems.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of an apparatus for explaining an embodiment of a magnetic field lens according to the first invention, and FIGS. 2 to 4 are other embodiments according to the first invention. FIG. 5 is a view for explaining an example, FIG. 5 is a view for explaining the second embodiment of the present invention, and FIGS. 6 and 7 are views for explaining the configuration of an objective lens using a conventional magnetic field lens. FIG. 1: Yoke 3: Cooling block 4: Tube 5a: Upper pole piece 5b: Lower pole piece 6: Sample holder 8: Objective lens aperture 9: Detector 10: Strip conductor 11, 14: Coil 12: Hole 13a, 13b: Notch S: Sample

Claims (2)

(57) [Claims] 1. A coil formed by turning a band-shaped conductor in an annular shape is fitted in an annular yoke to form a magnetic field lens, and a hole or notch is formed in said coil to reach from an outer peripheral portion to an inner peripheral portion. A magnetic field lens in an electron microscope or the like, wherein a space is formed in the annular yoke by providing a portion. 2. A magnetic field lens formed by fitting a coil formed by turning a strip conductor in an annular shape into an annular yoke, wherein the whole section or part from the start to the end of the winding of the strip. A magnetic field type lens in an electron microscope or the like, wherein the coil is turned while shifting the winding position in the width direction of the band in a target section to form a space between the upper surface or lower surface of the coil and the yoke.