JP2008305597A - Electron emitting element, electron gun, and electron beam application device using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize an electron emitting element and an electron gun having a high luminance and a narrow energy width and an electron microscope and an electron beam lithography system which mount the electron emitting element and the electron gun and have a high luminance and a high resolution. <P>SOLUTION: It is thought that, in an electron emitting element using a tubular substance having carbon as a principal component, electrons are emitted from near a five-membered ring of a closed structure region. A tube of large diameter is necessary in order to reduce energy dispersion effect by space electron rebounding by widening the five-membered ring interval. This device realizes a large diameter tube structure of a stable structure by reducing dynamic distortion of the cap structure. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electron-emitting device, an electron gun, and an electron beam application apparatus on which the electron-emitting device is mounted.

  An electron microscope apparatus or an electron beam drawing apparatus using carbon nanotubes containing carbon as a main component as an electron source has a high angular current density, and an electron beam with high brightness can be obtained (Japanese Patent Application Laid-Open No. 2004-79223 (Patent Document). 1)).

JP 2004-79223 A

  However, with the miniaturization of samples to be observed and processed, there is a need for electron emitters and electron guns with higher brightness and narrow energy width. In addition, when an electron beam is irradiated by applying a strong electric field in order to obtain high luminance, the electron-emitting device is easily destroyed and there is a problem in durability, so that it is difficult to increase the luminance.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an electron source / electron gun with high brightness and narrow energy width. Furthermore, it aims at providing the high-resolution electron microscope and electron beam drawing apparatus which can respond to the sample to refine | miniaturize.

  A feature of the present invention that solves the above-mentioned problems is the invention described in the claims, but among the tube-shaped substances mainly composed of carbon, a substance having a particularly thick tip is used as an electron emission source. There is.

  The electron-emitting device of the present invention comprises a conductive base material and a tubular substance fixed to the base material. The substrate may be used as an electrode for electron emission. The tube-shaped substance containing carbon as a main component is made of a carbon nanotube or a substance in which a substance other than carbon is mixed with a part of the carbon nanotube.

  As a result of the study, the inventors of the present application have thought that it is effective to use a tube having a large diameter in order to narrow the energy width of emitted electrons emitted from the electron emission source. This is because the space repulsion between electrons can be reduced by widening the interval between the five-membered rings serving as emission sites. Therefore, it is effective to use a tube having a large diameter for an electron-emitting device that emits an electron beam with high brightness and a narrow energy width.

  According to the present invention, an electron gun having a high luminance and a narrow energy width, a high resolution electron microscope, and an electron beam drawing apparatus can be provided.

  The tube-shaped substance formed with carbon as a main component includes a cap portion having a hemispherical shape and a shaft portion having a substantially cylindrical shape. Carbon or other added elements form a sheet-like substance composed of a continuous body of a five-membered ring structure and a six-membered ring structure, and a multilayer structure in which sheet-like substances are laminated is formed. The continuum of the six-membered ring structure is substantially flat and is bent at the part of the five-membered ring structure included in a part. The shaft portion has a substantially six-membered ring structure, and is combined with a cap portion having a plurality of five-membered rings to form a tube shape having a closed structure at the end.

<Example of thin carbon nanotube and thick carbon nanotube>
FIG. 1A is a schematic diagram of a thin carbon nanotube having a diameter of about 1 to 10 nm. It consists of a cylinder part with a nested cylinder and a cap part with a hemispherical dome shape. In calculation, a carbon nanotube consisting of a five-membered ring and a six-membered ring has six five-membered rings in the cap part, and that part becomes the apex, but if the diameter of the carbon nanotube is thin, it is actually almost hemispherical. It becomes.

  FIG. 1B is a schematic view of a typical shape of a thick carbon nanotube having a diameter of 30 nm or more. Although it is columnar as a whole, both the cylinder part and the dome part have a structure in which polygons are nested. There is usually a five-membered ring at the top of the polygon. The five-membered ring is the most stable structure when the opening angle is calculated to be 113 degrees.

<Ideal and real forms of CNT>
FIG. 2A is an example of an ideal shape in which three of the six apex angles of the cap portion are in the same plane. Actually, the shape is as shown in FIG. In FIG. 2B, since the cap portion is joined to the cylinder portion, there is a concern that the cap portion is distorted and the mechanical strength of the cap portion is weakened. Therefore, when such a tube is used as an electron source, the cap structure may be damaged by the applied electric field. In the present invention, the strength of the cap portion of the thick tube can be increased by bringing the shape of the cap portion closer to a sphere larger than the hemisphere.

  Here, among the vertices of the cap portion, the distance between the vertex closest to the central axis of the tube and the central axis is preferably 30 nanometers or less, and more preferably 10 nm or less. This is because when the distance is 30 nm or more, the orbit of the emitted electron beam is shifted from the central axis, and the emitted electron beam cannot be used efficiently.

  In addition to carbon, the constituent elements of the tube may be Group 3 and Group 5 elements. Specifically, nitrogen, boron, or the like can be used. If these non-carbon elements are contained as 2 atom% or more as constituent elements of the tube, there is an effect of narrowing the energy width of emitted electrons by modulating the density of electron states.

<Very thick CNT>
As shown in FIG. 3A or 3B, the outermost layer of the closed structure portion at the end has a polyhedral structure. In the case of a relatively thick tube having a diameter of 50 nm or more, the angle formed between the normal line of each plane constituting the cap portion and the central axis in the length direction of the tubular substance is 90 degrees as viewed from above the cap structure. By using a structure in which at least one plane exceeding the plane is present, the opening angle of the apex can be set to the most stable 113 degrees. Therefore, the distortion of the cap portion is alleviated and the mechanical strength of the cap portion is reduced. It can be improved dramatically.

  When there is one or more planes exceeding 90 degrees, it is possible to adopt a structure in which the opening angle of the vertex is geometrically 113 degrees.

<Match rod shape CNT>
In addition, as shown in FIG. 4A or FIG. 4B, in the case of a relatively thin nanotube having a diameter of about 10 nm, the cap region is made hemispherical or more to reduce the distortion of the cap portion, The mechanical strength of the cap portion can be dramatically improved.

  In the tube shown in FIG. 1, it is known that the cap region includes six five-membered rings. On the other hand, in the tube shown in FIGS. 3 and 4, the cap portion includes seven or more five-membered rings. In order to construct a spherical structure exceeding the hemisphere, seven or more five-membered rings are required geometrically.

<CNT manufacturing method>
A carbon nanotube having a large diameter can be formed by a vapor phase growth method. Vapor-grown carbon fiber is well known as a tube having a large diameter (Japanese Patent Laid-Open No. 58-197314). Moreover, you may select a carbon nanotube with the front-end | tip part diameter more than a fixed value from the carbon nanotube produced by the other well-known manufacturing method.

(Electronic gun)
In Example 1, an example of the electron gun of the present invention will be described. FIG. 5 is a diagram showing a configuration example of the electron gun of the present invention. The electron-emitting device of the present invention has a configuration in which one tubular substance containing carbon as a main component is bonded to a conductive substrate 501.

  In addition, the electron gun of the present invention includes a cathode electrode 508 composed of a conductive base material 501, an electrode 502, and an electrode support base 503, an extraction electrode 504 for emitting electrons from the cathode electrode, and an acceleration of the electrons. Accelerating electrode 505. The extraction electrode 504 applies a positive voltage to the cathode electrode 508 by the extraction electrode power source 506. The acceleration electrode 505 applies a positive voltage to the cathode electrode by the acceleration electrode power source 507. As a result, an electron gun with high brightness and a narrow energy width can be configured.

  The carbon nanotube used in this example is the tube shown in FIG. 3A, and the electron emitting element and the electron gun as described above have improved strength when a strong electric field is applied.

(Electronic gun)
Next, a second embodiment of the present invention will be described with reference to FIG. The second embodiment is different from the first embodiment in that a magnetic lens 604 with less spherical aberration is used instead of the extraction electrode. With such a magnetic field immersion type electron gun configuration, an electron gun with high brightness and a narrow energy width can be configured.

(Scanning electron microscope)
Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 7 shows a configuration diagram of a scanning electron microscope equipped with the electron gun of the present invention. The scanning electron microscope processes an electron beam emitted from an electron gun 701 with an anode electrode 702, a first converging lens 703, a second converging lens 704, and an objective lens 705, and finally scans the beam with a scanning coil 706 to obtain a sample. This is an apparatus for obtaining an enlarged image of the sample 707 by detecting secondary electrons emitted from the 707 by a secondary electron detector 708. The electron orbit 709 is also shown in the figure. The inside of the apparatus is maintained at a high vacuum, and the sample 707 can be mechanically moved and rotated from the outside of the apparatus. By mounting the electron gun of the present invention on a scanning electron microscope, a scanning electron microscope can obtain secondary electron images and reflected electron images with much higher resolution and brightness in a shorter time than conventional devices. Was able to be realized. In addition, since the length-measuring scanning electron microscope for observing a microfabricated pattern and measuring dimensions in a semiconductor process has the same configuration as that shown in FIG. Can do.

  The configuration of the electron microscope apparatus equipped with the electron gun of the present invention is not limited to that shown in FIG. 7, and any apparatus configuration may be adopted as long as the characteristics of the electron gun of the present invention can be sufficiently obtained. It is possible.

(Electron beam drawing device)
Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 8 shows a configuration example of an electron beam drawing apparatus equipped with the electron gun of the present invention. The basic configuration of the electron optical type is substantially the same as that of the scanning electron microscope of FIG. 7, and a blanker 810 for turning on / off the electron beam is provided between the first converging lens 803 and the second converging lens 804. The point to provide is different. The electron beam drawing apparatus forms a fine pattern by irradiating a sample 807 coated with an electron beam resist sensitive to an electron beam with a finely focused electron beam. By mounting the electron gun of the present invention, a remarkably narrow beam diameter can be obtained compared to the conventional case, so that a finer pattern can be drawn. Furthermore, since a high-luminance beam can be obtained, a significantly higher throughput can be realized compared to the conventional case.

The principle explanatory drawing of this invention. The principle explanatory drawing of this invention. The principle explanatory drawing of this invention. The principle explanatory drawing of this invention. The principle explanatory drawing of this invention. The principle explanatory drawing of this invention. The principle explanatory drawing of this invention. The principle explanatory drawing of this invention. Explanatory drawing of the 5th Example of this invention. Explanatory drawing of the 6th Example of this invention. Explanatory drawing of the 7th Example of this invention. 1 is a configuration example of an electron beam drawing apparatus of the present invention.

Explanation of symbols

501 Electroconductive base material 502, 602, electrode 503, 603, electrode support base 504, one element bonded, extraction electrode 505, 605, acceleration electrode 506, 606, extraction electrode power supply 507, 607 acceleration electrode power supply 601, one electron emission element of the present invention Electromagnetic gun 702, 802 Anode electrodes 703, 803 First converging lenses 704, 804 Second converging lenses 705, 805 Objective lenses 706, 806 Scanning coils 707, 807 Sample 708, 808 Secondary electron detector 709, 809 Electron orbital 810 Blanker

Claims (7)

An electron-emitting device comprising a tube-shaped substance whose main component is carbon having at least one end having a closed structure, and a conductive base material for fixing the tube-shaped substance,
The outermost layer of the closed structure portion of the end portion has a polyhedral structure;
The electron-emitting device according to claim 1, wherein an angle between at least one of the plane normals constituting the polyhedral structure and an axis in a length direction of the tubular substance is larger than 90 degrees. An electron-emitting device comprising a tube-shaped substance whose main component is carbon having at least one end having a closed structure, and a conductive base material for fixing the tube-shaped substance,
An electron-emitting device, wherein the outermost layer of the closed structure portion at the end has a spherical structure, and the spherical structure is a hemisphere or more. An electron-emitting device comprising a tube-shaped substance whose main component is carbon having at least one end having a closed structure, and a conductive base material for fixing the tube-shaped substance,
The outermost layer of the closed structure portion at the end is formed of a continuum of a five-membered ring structure and a six-membered ring structure composed of a plurality of atoms, and the closed structure portion has seven or more five-membered ring structures. An electron-emitting device characterized by existing.   4. The electron-emitting device according to claim 1, wherein the tube has a plurality of five-membered ring structures composed of atoms in the outermost layer of the closed structure portion at the end portion, and the central axis in the tube length direction The distance from the center of the five-membered ring closest to the central axis is 30 nanometers or less.   5. The electron-emitting device according to claim 1, wherein the tube contains at least one of Group 3 and Group 5 elements as elements constituting the tube. . An electron gun having a cathode made of an electron-emitting device, an extraction electrode for emitting electrons from the electron-emitting device, and an acceleration electrode for accelerating the emitted electrons,
The electron-emitting device includes a tube-shaped substance whose main component is carbon having at least one end having a closed structure, and a conductive base material for fixing the tube-shaped substance, and the outermost layer of the closed structure portion at the end. The electron gun has a polyhedral structure, and an angle between at least one of the normals of the planes constituting the polyhedral structure and an axis in the length direction of the tubular substance exceeds 90 degrees. A cathode made of an electron-emitting device, an extraction electrode for emitting electrons from the electron-emitting device, an acceleration electrode for accelerating the emitted electrons,
An electron microscope having a lens group for focusing the emitted electrons,
The electron-emitting device includes a tube-shaped substance whose main component is carbon having at least one end having a closed structure, and a conductive base material for fixing the tube-shaped substance, and the outermost layer of the closed structure portion at the end. Has an polyhedral structure, and at least one of the plane normals constituting the polyhedral structure has an angle of 90 degrees or more with the longitudinal axis of the tubular substance, .

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