JP2018147871A - Electron gun - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-brightness electron gun cathode with a low work function.SOLUTION: An electron gun is constructed by lanthanum or cerium atom and a cathode material in which a carbon atom and a boron atom are combined in a predetermined adjacent distance. In a work function of the electron gun cathode, the work function of LaB6 or CeB6 is 2.7 eV. However, the work function can be reduced to 1.7 eV or less by diffusing, mixing, or combining the carbon atom, and a brightness of 10A/cmsteradian can be achieved with 50kV under a low temperature operation of 1200°C or less. By reducing the work function, a high brightness low temperature operation can be performed. A life of the electron gun is improved by preventing the boron atom and the carbon atom from being burned due to an oxygen concentration at high vacuum of 10pascal or more. Furthermore, by adhering a supply material of the carbon atom to the cathode material or a heater as a supply source, the life can be further improved.SELECTED DRAWING: Figure 1

Description

  In electron beam lithography technology used in the lithography field for drawing circuit patterns in semiconductor (LSI) manufacturing processes, a high-intensity electron gun with a high thermionic emission current strength of a thermoelectron gun is required to dramatically increase the processing capability. Realization is possible. At present, an electron beam lithography apparatus requires a multi-column electron beam lithography apparatus equipped with a large number of electron guns in order to increase the processing speed. It is desirable to maximize the brightness.

  In order for the electron gun to have high brightness, the so-called work function needs to be small. The work function represents energy for emitting electrons from the inside of the substance into the vacuum in eV units. The smaller this value, the easier it is to emit electrons.

  Whereas the work function of LaB6 or CeB6 conventionally used is 2.7 eV, in the present invention, an electron gun using an electron gun cathode material having a work function of 1.7 eV or less is realized as an invention. . Thereby, it is possible to increase the brightness by 10 times or more and to operate at a low temperature of 400 ° C. or more. In general, an electron gun cathode material having a small work function has a low vapor pressure and is likely to be exhausted. However, the electron gun cathode material of the present invention is a high-intensity long-life electron gun in which the vapor pressure does not decrease.

  Conventionally, a photolithography technique (optical lithography) in which a mask to be an original drawing is created by an electron beam drawing apparatus and the mask image is transferred to a semiconductor substrate (wafer) by light has been mainly used as a semiconductor lithography technique. In the optical lithography technology, from the principle that resolution is improved by shortening the wavelength of light, the wavelength of light has been shortened with the progress of miniaturization, from g-line (wavelength 436 nm) to i-line (wavelength 365 nm). As a result, miniaturization, high integration, and cost reduction have been achieved. At present, excimer laser light having a wavelength of 193 nm is used. In the future, a lithography technique using an ultrashort ultraviolet ray having a short wavelength of 13.4 nm will be developed. However, development of a high-throughput fine pattern forming apparatus has been delayed.

  On the other hand, the development cost of masks has been increasing with the progress of semiconductor miniaturization, and has reached several hundred million yen per type of LSI. An electron beam lithography system has been used for mask development because of its feature of having a pattern generation function. However, the processing time has increased with the progress of optical lithography technology, such as the introduction of super-resolution technology that realizes transfer performance below the wavelength of light and the enlargement of mask data due to high integration. Ten hours have come to be taken.

  The electron beam drawing method has been developed from a method called one-stroke writing with a narrowed electron beam to a drawing method such as a variable rectangle method that draws several square microns at a time. However, with the current variable rectangular beam, the vertical and horizontal widths of the variable rectangular beam that can be used become smaller in synchronization with the increasingly finer mask patterns in recent years.

  For this reason, the number of shots has increased in an accelerating manner, and some shots that take 200 hours (8 days) or more per mask layer have appeared.

  Therefore, attention will be focused on maskless lithography technology, which aims to reduce the mask price rise by shortening the mask drawing processing time, and to realize direct drawing on the wafer by the electron beam drawing apparatus without using an expensive mask. Therefore, a multi-beam type apparatus that performs drawing processing in parallel using a plurality of electron beams has been proposed, and it is expected to increase the processing capability by several hundred times.

  In the maskless lithography technology, industrially useful processing capability is required to write 10 or more 300 mm diameter wafers per hour. For this purpose, it is required to realize a multi-electron beam drawing apparatus using about 100 electron beams because of the processing capability per electron beam. Therefore, in order to generate 100 (10 × 10) electron beams on a 300 mm wafer, a technique for simultaneously generating a plurality of electron beams at a pitch of 30 mm or less is required.

  When electron beams are simultaneously generated at a pitch of 30 mm or less, the electric fields of adjacent electron guns affect each other between the electron guns. Therefore, the size of the electron gun is preferably 15 mm or less.

  The processing capability of the electron beam drawing apparatus is proportional to the electron beam intensity and inversely proportional to the sensitivity of the resist, which is a photosensitive material. In the electron beam drawing apparatus, the beam is blurred by a large current due to the interaction between electrons, and therefore there is a situation that the current value must be limited to about 1 μA per electron beam.

  On the other hand, it is considered that an extremely fine (15 nm to 10 nm line width) LSI pattern cannot obtain the intended drawing accuracy unless it is based on a resist with low sensitivity (around 100 μC / cm 2). Due to these restrictions, a 300 mm wafer having a size of approximately 600 cm 2 requires a drawing time of 60,000 seconds or more. With approximately 100 multi-columns, this can be 600 seconds or less.

  As an electron gun of such an electron beam drawing apparatus, a LaB6 or CeB6 frustoconical thermionic emission electron gun has been conventionally used. The diameter of the frustoconical portion at the tip was 30 μmφ, and the inclination angle of the frustoconical shape was about 60 degrees. This electron gun was used by heating at about 1600 ° C. under a vacuum of 1 × 10 −6 pascal or higher. The luminance at this time was 1 × 10 6 A / cm 2 steradian at 50 kV, which was quite large. However, at 1600 ° C., the sublimation of LaB6 or CeB6 with oxygen caused the depletion of 10 μm / 700 hours (1 month). Occurred. Therefore, since the tip frustoconical portion having a diameter of 30 μm is sharpened to about 10 μm in diameter, the brightness is further increased, but the irradiation uniformity is deteriorated. That is, since only a narrow range is uniformly irradiated, the pattern accuracy deteriorates. For this reason, the life of an electron gun using LaB6 or CeB6 is only about one month, and an electron beam lithography apparatus that normally requires a life of half to one year is basically insufficient. For this reason, there is a system that uses a turret electron gun unit or the like that can rotate and replace 10 LaB6 or CeB6 electron guns.

  If the work function of the electron gun cathode material is reduced, lower temperature operation and higher brightness can be achieved simultaneously. The LaB6 or CeB6 used so far required a work function as high as 2.7 eV, 50 kV, a luminance of 1 × 10 6 A / cm 2 steradian, and an operating temperature of 1600 ° C. or higher. Therefore, if the degree of vacuum is further increased to reduce the oxidative consumption due to oxygen to 1 × 10 −7 pascal, the oxidative consumption can be sufficiently reduced, but the evaporation of LaB6 or CeB6 itself cannot be reduced and 2.5 μm / 700 hours (1 Month). For this reason, the lifetime of the electron beam writing apparatus is only about four times longer and requires one year of life, and it is necessary to replace three electron guns. Therefore, an electron gun using an electron gun cathode material having a low work function capable of realizing a low temperature operation of 1200 ° C. by reducing the work function to 1.7 eV or less, realizing 1 × 10 7 A / cm 2 steadian or more at a luminance of 50 kV is required. Met.

  Under such circumstances, there is a need in the industry for an electron gun having a cathode material that has a high luminance of LaB6 or CeB6 or higher, low temperature operability, and can simultaneously achieve a long lifetime of one year or more. It was.

Japanese Patent Publication No. Hei 8-212952 Japanese Patent Publication No. 6-181029

Electron / Ion Beam Handbook 3rd Edition, Japan Society for the Promotion of Science, 132nd Committee Editorial Board Chairman Katsumi Ura Nikkan Kogyo Shimbun October 28, 1998 P119 Figure 4.3 Method of Holding Compound Cathode

  A large number (approximately 100) of electron beams are simultaneously generated on a 300 mm wafer to realize a multi-electron beam drawing apparatus, which has a throughput of 6 sheets or more per hour, and 100 electron guns all have one year. In order to form an electron gun having a life of (12 months) or more, there are the following problems.

  While the work function of LaB6 or CeB6 is 2.7 eV, it is necessary to manufacture an electron gun that can reduce the work function to 1.7 eV or less and obtain high brightness at low temperature operation.

  The electron gun according to the present invention is characterized by having a cathode material in which lanthanum or cerium atoms, carbon atoms, and boron atoms are bonded at a predetermined adjacent distance.

  As the cathode material, it is preferable that a solution containing carbon atoms is applied to the surface of LaB6 or CeB6 crystals, and carbon atoms are injected and diffused into the crystals. Moreover, it is preferable that the solution containing a carbon atom is a fatty acid glyceride having a chain hydrocarbon chain and esterified with a glycerin group.

  The present inventors have confirmed through experiments that the work function can be lowered by injecting and diffusing carbon atoms into LaB6 or CeB6 crystals. The reason for this is that lanthanum atoms and carbon atoms coexist in the crystal cells formed with boron atoms, probably because carbon atoms having a higher electronegativity than boron are implanted and diffused into LaB6 or CeB6 crystals. Electrons of a small lanthanum atom having an electronegativity of 2.5 and an electronegativity of 1.1 are attracted to a large carbon atom, and the lanthanum atom has a relatively positive charge. It is considered that electrons emitted from carbon atoms and boron atoms are likely to be emitted into a vacuum through lanthanum atoms. The present inventors have not conducted an experiment in which a carbon atom and a lanthanum atom are directly bonded without intervention of a boron atom. Although there is a possibility that the work function can be lowered only by carbon atoms and lanthanum atoms without the presence of boron atoms, the work function may not necessarily be smaller than that of the present invention. The inventors of the present invention have confirmed by experiment that an electron gun cathode material having a low work function of 1.7 eV or less is obtained by injecting and diffusing carbon atoms into LaB6 or CeB6 crystals, and it has been found that reproducibility can be obtained. Therefore, this is the invention of the present inventors. This work function could be changed with the concentration of the carbon atom-containing liquid and the temperature and time of implantation diffusion. By properly selecting these conditions, a desired work function could be realized. Incidentally, the minimum work function was about 0.9 eV.

As described above, according to the electron gun of the present invention, the electron gun cathode material is a material obtained by injecting and diffusing carbon atoms into a LaB6 or CeB6 crystal as an electron gun cathode material, and emits thermoelectrons. Therefore, by reducing the work function of 2.7 eV of LaB6 or CeB6 to 1.7 eV or less, the operating temperature of the electron gun could be lowered from 1600 ° C. to 1200 ° C. . At the same time, the luminance of 1 × 10 6 A / cm 2 steadian at 50 kV of conventional LaB6 or CeB6 could be increased 10 times or more. Due to the low-temperature operation, the oxidative consumption of the electron gun cathode material and the evaporation of the material itself can be sufficiently reduced, and a long-life electron gun having a lifetime of one year or more can be configured. Since the self-evaporation rate of LaB6 is 1/7 at 100 ° C., the self-evaporation rate due to a temperature drop of 400 ° C. is 1/400. The oxidation consumption rate of boron becomes almost 0 at a vacuum degree of 10 ⁻⁷ pascal.

  Since this electron gun stably emits electrons, an electron gun suitable for a multi-electron beam drawing apparatus can be realized.

  Therefore, the high-intensity long-life electron gun is a powerful means for realizing an electron beam drawing apparatus. Brain computer industry based on artificial intelligence and neuron imitation with micropatterns and autonomous driving cars, various robots, robots for working at dangerous places, robots for nursing care, interactive coexistence robots, large-scale buildings and large-scale construction quickly Robots that work, upload human consciousness, copy human memory consciousness, thinking process at that time, and then take over the human thinking method and memory and live consciously indefinitely have an infinite life In order to make the semiconductor industry such as artificial brain such as artificial brain into a huge industry, an electron beam drawing apparatus based on an electron gun makes a great contribution.

  This electron gun can be used as an electron gun for an X-ray generator. In that case, the current density is usually 400 ° C. lower than LaB6 and a current density of 10 times is possible, so the size of the bright spot of the X-ray generation light source is reduced to one third, and the lifetime becomes 2400 times. For this reason, in the X-ray apparatus, image sharpening and long life can be achieved. Accordingly, medical X-ray devices have made significant progress and contributed greatly to the development of the medical X-ray field.

  Similarly, when used at 1200 ° C. as an electron gun for an electron microscope, the market is developed as a general electron microscope with a long life and a large current density of 10 times or more. Although it is a special application, when the work function can be reduced to 1 eV, it can be used at 1600 ° C. and the current density can be increased 37,000 times. Since the resolution of the electron microscope is determined by the square root of the current density when the current value is the same, the beam size can be reduced to 1/192. Since the resolution of the current scanning electron microscope is about 2 nm, a resolution of 10 pm can be achieved. This means that, for example, the size of an oxygen atom is 120 pm, so that one oxygen atom can be recognized sufficiently. That is, it means that the scanning electron microscope using this electron gun can recognize the atomic images on the surface and their arrangement in an instant as an image. Of course, when only the surface is observed with sufficiently low acceleration and there are multiple atomic layers in the thickness direction, calculation of image processing to obtain an image of a desired cross-sectional atomic layer is required. The type of each atom can be identified by measuring Auger electrons and fluorescent X-rays of each atom. Therefore, it is revolutionary that the atomic arrangement structure of all observation objects can be separated and analyzed by image processing. Direct observation of what is actually happening at the atomic level is powerful in the field of medicine, biology, life phenomena, physics, chemistry, etc. It is obvious to do. For this reason, it is a great contribution to contribute to the advancement of human scientific progress in the fields of technological development and invention.

It is a figure explaining 1 of the Example of the electron gun of this invention. It is a figure explaining the arrangement | positioning of the boron atom and the lanthanum atom in LaB6 or CeB6 crystal structure. It is a figure explaining the arrangement | positioning of the lanthanum atom and carbon atom in the LaB6 or CeB6 crystal structure of this invention. It is a figure explaining the arrangement | positioning of the lanthanum atom and carbon atom in the LaB6 or CeB6 crystal structure of this invention. It is a chemical formula which shows the structure of the various organic polymer used for this invention. It is a figure explaining the surface state which the organic polymer which consists of a chain | strand-shaped hydrocarbon row | line adhered to the surface of the LaB6 or CeB6 crystal | crystallization which is an electron gun cathode material of this invention. It is a figure explaining the atomic arrangement | sequence and electron emission condition of a lanthanum atom, a carbon atom, and a boron atom in the amorphous state of this invention. It is a figure explaining the atomic arrangement | sequence and electron emission condition in the crystal state of the LaB6 or CeB6 crystal | crystallization of this invention, and a carbon atom. It is a figure explaining the mode of consumption of the electron gun formed with the usual LaB6 or CeB6 crystal. It is a figure explaining 2 of the Example of the electron gun of this invention. The electron gun cathode tip of the present invention is made of a refractory metal that does not react with LaB6 or CeB6, such as rhenium, and a cathode tip that emits electrons by attaching a combination of LaB6 or CeB6 crystals and carbon atoms to the tip. And a structure for supplying a combination of LaB6 or CeB6 and carbon atoms at the tip of the electron gun cathode reduced by evaporation. It is a figure explaining 3 of the Example of the electron gun of this invention. The electron gun cathode tip of the present invention is made of a refractory metal that does not react with LaB6 or CeB6, such as rhenium, and a cathode tip that emits electrons by attaching a combination of LaB6 or CeB6 crystals and carbon atoms to the tip. And a structure for supplying a combination of LaB6 or CeB6 and carbon atoms at the tip of the electron gun cathode reduced by evaporation. It is a figure explaining 4 of the Example of the electron gun of this invention. In the electron gun cathode of the present invention, a groove serving as a reservoir is dug in a direction perpendicular to the electron gun cathode tip flat part, filled with an organic polymer therein, and the organic polymer is supplied to the electron gun cathode tip part, It is a figure explaining the structure for supplying a carbon bond to a LaB6 or CeB6 crystal | crystallization. It is a figure explaining 5 of the Example of the electron gun of this invention. The groove serving as a reservoir for holding the organic polymer in the electron gun cathode of the present invention is formed in the lower part of the LaB6 or CeB6 crystal, in the electron gun cathode part sandwiched between the graphite heaters, and in the direction of electron emission of the electron gun. It is a figure explaining the structure which digs in a horizontal direction and supplies an organic polymer to an electron gun cathode tip by containing an organic polymer in a hole, and supplies the combined substance of carbon to a LaB6 or CeB6 crystal. . It is a figure which shows the crystal structure of the lanthanum dicarbide relevant to this invention.

Embodiments for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is a diagram for explaining an example 1 of an electron gun according to the present invention. High heat-resistant spring-like metals 102 a and 102 b are connected and installed on the ceramic disk 101. High heat-resistant spring-like metals 102a and 102b hold PG (pyrolytic graphite) heaters 104a and 104b and LaB6 single crystal 103 with spring force. A heating current flows through 102a, 104a, 103, 104b, and 102b, and the LaB6 or CeB6 single crystal 103 is heated to 1200 ° C. by the heat generated by the PG (pyrolytic graphite) heaters 104a and 104b. −50 kV is applied to the LaB6 or CeB6 single crystal 103. Note that a circular flat portion has a diameter of 20 μm to 50 μm at the tip of the LaB 6 or CeB 6 single crystal 103.

The LaB6 or CeB6 single crystal 103 of the present invention is subjected to a completely different manufacturing method from the conventional LaB6 or CeB6 single crystal. Before or after assembling into the structure of FIG. 1, a liquid or solid organic polymer 106 containing carbon atoms is attached to the side surface and the entire tip surface of LaB6 or CeB6, or only to the tip surface, and the temperature is increased. A predetermined temperature between 1200 ° C. and 1600 ° C. is selected and maintained at this temperature, whereby carbon atoms are implanted and diffused into the LaB 6 or CeB 6 single crystal 103. Here, referring to FIG. 2, carbon atoms are implanted and diffused into the center of each of the cubic crystal lattice cells of 48 boron atoms. The description will now move to FIG. As shown in FIG. 3a, a structure is adopted in which lanthanum atoms 202 and implanted and diffused carbon atoms 301 are installed as a pair of atomic groups at the center of each of 48 cubic crystal lattice cells of boron. The work function of this electron gun cathode material is 1.7 eV or less, and when operating at 1200 ° C., the brightness is 10 ⁷ A / cm ² steadian at −50 kV.

  In addition, by attaching a liquid or solid containing carbon atoms, selecting a predetermined temperature between 1200 ° C. and 1600 ° C., and maintaining this temperature for 6 to 24 hours, the LaB6 or CeB6 single crystal 103 Although carbon atoms 301 are injected and diffused inside, the liquid component or solid component of the diffusion source remaining on the surface of LaB6 or CeB6 after maintaining at a high temperature should be removed if an excess component seems to remain. If the surplus component seems to evaporate from the surface of the LaB6 or CeB6 crystal during high temperature holding in a vacuum, it can be used as it is as an electron gun. Details of the organic polymer 106 that is a liquid or solid containing carbon atoms will be described later.

  Returning to FIG. 1, the description will be continued. The Wehnelt electrode 105 is an axisymmetric object, is made of metal, and is connected to a negative potential of −50 kV to −53 kV. Therefore, the electrons emitted from other than the tip of the LaB6 single crystal 103 are suppressed by the contour line 107 indicating the potential due to Wehnelt. The anode 109 is grounded. The equipotential line 108 near the anode is relatively straight. The emitted electrons 110 due to thermionic emission pass through the opening of the anode 109. Irradiation distribution 111 of emitted electrons by thermionic emission is almost similar to a Gaussian function.

LaB6 or CeB6 single crystal 103 is heated by PG (pyrolytic graphite) heaters 104a and 104b, and the heating power consumption is S × T ^{4 where} the sum of the areas of the high temperature part is S and the absolute temperature is T. Is proportional to Therefore, in order to suppress heating power consumption, it is necessary to make the surface area of the electron gun cathode and the holding jig as small as possible. Since the electron gun cathode material of the present invention has a work function as low as 1.7 eV, the temperature can be lowered. However, assuming that 100 electron guns are used in parallel in a multi-column, the heating power consumption is Since it becomes 100 times by simple calculation, it is necessary to make the total area of the LaB6 or CeB6 single crystal 103 approximately half or less. For this reason, the LaB6 or CeB6 single crystal 103 needs to have a width of 0.35 mm or less and a length of 2.5 mm or less. Thereby, it becomes 50% or less of the conventional surface area. On the other hand, the fourth power term of T decreases to about 0.213 because it decreases with the fourth power of the ratio of 1600 ° C. (absolute temperature 1873K) and 1200 ° C. (absolute temperature 1273K). When combined with the reduced surface area, the power consumption is 0.1 times that of the conventional electron gun. Therefore, even if 100 are arranged, the increase can be suppressed to about 10 times that of a single electron gun.

FIG. 2 is a diagram showing the structure of a LaB6 or CeB6 crystal used in the present invention.
Six boron atoms 201 form a regular octahedron. Eight regular octahedrons form a cube. A lanthanum atom 202 exists at the center of a cube formed by eight regular octahedrons. When the number of boron atoms 201 associated with one lanthanum atom 202 is calculated, it becomes 6/8 × 8, and it can be seen that six boron atoms 201 are paired with one lanthanum atom 202. Therefore, it is LaB6 or CeB6. The work function of the LaB6 or CeB6 crystal in FIG. 2 is 2.7 eV.

  3a and 3b are diagrams showing crystal structures of the lanthanum atom 202, the carbon atom 301, and the boron atom 201 of the present invention. FIG. 3a shows eight regular octahedrons of boron atoms 201 and one side of a crystal arranged in a cube is 415.52 pm, but a lanthanum atom 202 and a carbon atom 301 are slanted on the central cross section in a cross section parallel to the side of the cube. It represents a side-by-side structure. At this time, the total distance between the lanthanum atom 202 and the carbon atom is 564 pm. Since the diagonal distance of the cross section parallel to the side face of the LaB6 crystal cube is 587 pm, the lanthanum atom 202 and the carbon atom 301 can enter the cross section at the center of the LaB6 crystal in a diagonal direction. In this case, the work function of the LaB6 crystal containing carbon atoms 301 can be 1.7 eV or less.

  FIG. 3b shows a structure in which lanthanum atoms 202 and carbon atoms 301 are inserted in a different arrangement from FIG. 3a. The total length of the lanthanum atom 202 and the carbon atom 301 is 564 pm. On the other hand, the three-dimensional diagonal distance of a cube of LaB6 crystal cells is 719.7 pm. It is considered that carbon atoms can enter LaB6 crystal lattice cells in this way. Further, in the case of such an atomic arrangement, one or two additional carbon atoms 301 can be added. Therefore, it is considered that one lanthanum atom 202 and one carbon atom 301 can enter one LaB6 crystal lattice cell from one to a maximum of three. In such a case, it is considered that the work function of the LaB6 crystal in which carbon atoms 301 are implanted and diffused can be 1.0 eV or less. Note that the same effect may be obtained even when hydrocarbon molecules are implanted and diffused into LaB6 or CeB6 crystals instead of carbon atoms.

FIG. 4 is a diagram showing an organic polymer that is a liquid or solid containing carbon atoms used in the present invention. Details of organic polymers that are liquids or solids containing carbon atoms will be described. A liquid containing carbon atoms or a solid organic polymer is applied to the surface of LaB6 or CeB6 crystal, and the temperature is selected between 1200 ° C. and 1600 ° C. and kept at this temperature for 6 to 24 hours. In order to prevent carbon atoms 301 from diffusing from the crystal surface at such a high temperature, the carbon-containing solution is different from a solution containing carbon in that the organic high molecule having a long chain molecule of a considerably large hydrocarbon. Must be a molecule. That is, the organic polymer preferably has a chain of hydrocarbon chains and is bonded with alcohol, glycol or glycerin. For example, an alkane molecule in which CH ₂ is 6 or more, about 100, and arranged in a long chain, that is, a paraffin molecule is preferable. In addition, when an alkane molecule in which 6 or more of CH ₂ are arranged in a long chain, that is, a paraffin molecule is described as R, it shares two or three plural alkane molecules or paraffin molecules. Alternatively, it may be polymerized by esterification with glycol or glycerin to form a fatty acid glyceride. Examples of organic polymers include fatty acid glycerides, 1 monoglycerides, 1,2-diglycerides, triglycerides, and glycerin, all of which contain carbon atoms in the organic polymer. In order to inject and diffuse carbon atoms on the surface of the LaB6 or CeB6 crystal, an organic polymer is required, but as a carbon source, not only a long chain alkane molecule or paraffin molecule but also not shown A benzene ring in which carbon atoms are arranged in a hexagon may be included. These contribute in the same way as an implantation diffusion source of carbon atoms.

  FIG. 5 is a diagram for explaining a surface state in which an organic polymer composed of a chain hydrocarbon chain is attached to the surface of a LaB6 or CeB6 crystal that is an electron gun cathode material of the present invention.

  The organic polymer is mainly composed of hydrogen atoms 501 and carbon atoms 301, and the carbon is selected by maintaining a predetermined temperature between 1200 ° C. and 1600 ° C. from the state of adhering to the LaB6 surface. The atoms 301 are separated from the hydrogen atoms 501 and the carbon atoms are separated from each other, and the carbon atoms 301 are injected and diffused into the LaB6 single crystal 103.

  During the implantation and diffusion, it is necessary that the remaining organic polymer adheres to the LaB6 or CeB6 crystal surface with sufficient strength so that it does not easily evaporate from the LaB6 or CeB6 crystal surface.

  The present inventors diffused carbon atoms 301 into LaB6 or CeB6 crystal lattice cells using alkane molecules, that is, paraffin molecules, and set the work function to 1.7 eV or less. Furthermore, fatty acid glycerides were formed by esterification with alkane molecules, that is, paraffin molecules and glycol molecules or glycerin molecules, and this was applied to the surface of LaB6 or CeB6 crystals. Then, by selecting a predetermined temperature between 1200 ° C. and 1600 ° C. and maintaining this temperature, carbon atoms 301 are injected and diffused into the LaB6 or CeB6 crystal lattice cell, and the work function is set to 1.7 eV or less. .

  FIG. 6 shows a cathode material in which carbon atoms 301 are bonded to amorphous LaB6 or CeB6 by ion implantation to bond lanthanum atoms 202, boron atoms 201, and carbon atoms 301 at a predetermined adjacent distance. Since the carbon atom 301 has a large electronegativity of 2.5 and the electronegativity of the lanthanum atom is 1.1, the lanthanum atom is relatively positively charged by attracting electrons of the lanthanum atom. Therefore, electrons emitted from the carbon atoms 301 and the boron atoms 201 are injected into the vacuum with a low work function of 1.7 eV in the form of being attracted to the positive charges of the lanthanum atoms 202.

  Similarly, FIG. 6 shows a cathode material in which carbon atoms 301 are implanted into amorphous LaB6 or CeB6 by sputtering to form a cathode material in which lanthanum atoms 202, boron atoms 201, and carbon atoms 301 are bonded at a predetermined adjacent distance. ing. Since the carbon atom 301 has a large electronegativity of 2.5 and the electronegativity of the lanthanum atom is 1.1, the lanthanum atom is relatively positively charged by attracting electrons of the lanthanum atom. Therefore, electrons emitted from the carbon atoms 301 and the boron atoms 201 are injected into the vacuum with a low work function of 1.7 eV in the form of being attracted to the positive charges of the lanthanum atoms 202.

  Similarly, FIG. 6 shows that carbon atoms 301 are attached to amorphous LaB6 or CeB6 by vapor deposition, and the temperature is raised to inject and diffuse, thereby bonding lanthanum atoms 202, boron atoms 201, and carbon atoms 301 at a predetermined adjacent distance. Also shown is a cathode material formed. Since the carbon atom 301 has a large electronegativity of 2.5 and the electronegativity of the lanthanum atom is 1.1, the lanthanum atom is relatively positively charged by attracting electrons of the lanthanum atom. Therefore, electrons emitted from the carbon atoms 301 and the boron atoms 201 are injected into the vacuum with a low work function of 1.7 eV in the form of being attracted to the positive charges of the lanthanum atoms 202.

  Similarly, FIG. 6 shows that carbon atoms 301 are implanted and diffused into amorphous LaB6 or CeB6 using methane, ethane, or propane gas, and lanthanum atoms 202, boron atoms 201, and carbon atoms 301 are adjacent to each other. Also shown is the formation of cathode materials joined by distance. Since the carbon atom 301 has a large electronegativity of 2.5 and the electronegativity of the lanthanum atom is 1.1, the lanthanum atom is relatively positively charged by attracting electrons of the lanthanum atom. Therefore, electrons emitted from the carbon atoms 301 and the boron atoms 201 are injected into the vacuum with a low work function of 1.7 eV in the form of being attracted to the positive charges of the lanthanum atoms 202.

  FIG. 7 is a diagram showing a reduction in work function due to carbon atoms entering the LaB6 or CeB6 crystal structure. Six boron atoms 201 gather to form a regular octahedron. Eight regular octahedrons gather to form a cube. A lanthanum atom 202 and a carbon atom 301 are inserted in pairs at the center of the cube. Since the electronegativity of the carbon atom 301 is high at 2.5 and the electronegativity of the lanthanum atom 202 is 1.1 and very low, the lanthanum atom 202 is charged with a positive charge, so that the electrons 701 are easily emitted toward the vacuum. The More specifically, an electron starting from the carbon atom 301 tends to be an electron 701 that is attracted to the lanthanum atom 202 and emitted into the vacuum. The work function at this time is as low as 1.7 eV. In FIG. 7, the electrons 702 and 703 are not emitted in the vacuum direction and do not affect the work function.

  FIG. 8 is a diagram showing how the shape of the electron gun material changes due to the oxidation consumption of the conventional LaB6 or CeB6 electron gun. The pre-use shape 801 of the LaB6 or CeB6 single crystal is consumed like the post-use shape 802 because the surface is oxidized and sublimated by heating for a long time. The operating temperature of LaB6 or CeB6 is around 1600 ° C. When the degree of vacuum is low and the oxygen concentration is high, the oxidation rate is high and sublimation is large. The sublimation amount is approximately 10 μm under the conditions of 1600 ° C., 10 −6 pascal, 700 hours. The sublimation amount is as high as 60 μm in half a year (6 months: 4200 hours).

  Therefore, the lifetime of LaB6 or CeB6 is said to be 1 month. In this case, when the tip of the single crystal is in the initial state of a circular truncated cone shape with a diameter of 30 μmφ, the uniform irradiation area of the central top of the electron density distribution function 806 is sufficiently wide. However, after 700 hours, the tip circular flat portion has a minimum diameter of 10 μmφ, and the electron density distribution function 807 at that time has a uniform irradiation area at the central top portion that is extremely small. In this state, the overlapping portion 804 of the two rectangular apertures 803 and 805 for forming the variable rectangular beam cannot be uniformly irradiated, and the function as the drawing apparatus is impaired. Therefore, the lifetime of irradiation uniformity in the LaB6 or CeB6 electron gun is within 700 hours, which means that the lifetime is one month.

Since the electron gun of the present invention has a low work function, it can be operated at a low temperature. When the operation is performed at a vacuum degree of 1 × 10 −7 pascal or higher at 1200 ° C., oxygen atoms are sufficiently small and lanthanum, The oxidation consumption of boron and carbon is sufficiently reduced. However, since there is evaporation of lanthanum, boron, and carbon itself, the amount of evaporation cannot be made zero. However, since the amount of evaporation is reduced to one-seventh when the temperature is reduced by 100 ° C., a life extension of 7 ⁴ = approximately 2400 times can be achieved by a temperature change of 400 ° C. from 1600 ° C. to 1200 ° C. Theoretically, it can be expected to withstand almost 200 years.

  FIG. 9 shows a second embodiment of the present invention. The flat part of the truncated cone shape of the rhenium substrate 902 has a diameter of 30 μm. Here, a powder obtained by pulverizing LaB6 or CeB6 crystals into crystal grains of 1 μm is dissolved in an organic polymer solvent containing carbon atoms, and a low work function cathode material 901 in which carbon atoms are injected and diffused into LaB6 or CeB6 crystals is attached. I'm clumsy. The substrate 902 needs to be rhenium in order not to react with LaB6 and CeB6 at high temperatures.

  The LaB6 or CeB6 crystal may be a deposited film. It may be a low work function cathode material 901 in which an organic polymer solvent containing a carbon atom is attached to a deposited film of LaB6 or CeB6 crystal and carbon atoms are injected and diffused into the LaB6 or CeB6 crystal.

  In the previous section, it was written that it can withstand almost 200 years theoretically, but it cannot be said that there is no case where the consumption is severe depending on the use conditions.

  When the cathode material 901 with a low work function is consumed, it is necessary to replenish the consumption of the electron gun cathode and maintain the performance. Therefore, a low work function with a mixture of LaB6 or CeB6 crystals and an organic polymer containing carbon atoms is required. A cathode material supply source 903 is provided on the rhenium substrate 902. When the low work function cathode material 901 is depleted, the temperature is raised and the low work function cathode material source 903 is evaporated and deposited on 901 to replenish the depletion of the electron gun cathode and maintain performance.

  FIG. 10 shows a third embodiment of the present invention. The flat cylindrical portion at the tip of the rhenium substrate 1002 has a diameter of 30 μm. Here, LaB6 or CeB6 is pulverized to a grain size of 1 μm and dissolved in an organic polymer solvent containing carbon atoms, applied, injected and diffused into LaB6 or CeB6 crystals, and a low work function cathode material 1001 is deposited. I'm clumsy. The substrate 1002 needs to be rhenium in order not to react with LaB6 and CeB6 at a high temperature. When the cathode material 1001 with a low work function is consumed, it is necessary to replenish the consumption of the electron gun cathode and maintain the performance. Therefore, a low work function with a mixture of LaB6 or CeB6 crystals and an organic polymer containing carbon atoms is required. A cathode material supply source 1003 is set on the rhenium substrate 1002. When the low work function cathode material 1001 is depleted, the temperature is raised and the low work function cathode material source 1003 is evaporated and deposited on top of 1001 to replenish the depletion of the electron gun cathode and maintain performance.

  FIG. 11 shows a fourth embodiment of the present invention. The electron gun cathode base 1101 is a cylinder of LaB6 or CeB6 crystal having an outer diameter of 110 μm, and has an electron emission portion with a diameter of 30 μm, a reservoir portion with a groove width of 20 μm cut by electric discharge machining, and an outer wall with a width of 20 μm. Yes. Since the electron gun cathode substrate 1101 in which a groove serving as a reservoir is formed is a LaB6 or CeB6 crystal, it has a long life because evaporation due to oxidation consumption is small under high vacuum. However, since the organic polymer that supplies carbon is more easily evaporated than the electron gun cathode base 1101 made of LaB6 or CeB6 crystals, it is necessary to fill the reservoir with the organic polymer 1102 in order to ensure the lifetime. is there. In addition, if the organic polymer is mixed and filled with a fine powder of boron or carbon, inadvertent evaporation can be prevented over a long period of time.

  FIG. 12 shows a fifth embodiment of the present invention. The electron gun cathode base 1201 has a truncated cone shape of LaB6 or CeB6 crystal having a tip of 30 μm in diameter, and has a hole that serves as a reservoir in a direction perpendicular to the axis of the emitted electrons 110 by thermoelectron emission, and continues from there to the tip. There is a groove, and the inside is filled with an organic polymer 1102. The organic polymer 1202 becomes vapor when the temperature is raised, and is supplied to the tip of the electron gun through a fine opening. With the supplied organic polymer 1202, carbon atoms are injected and diffused at the tip of the electron gun cathode base 1201 of LaB6 or CeB6 crystal. The reservoir does not necessarily have to be on the electron gun cathode base, but is placed in a highly heat-resistant spring-like metal, penetrates the passage hole in the PG graphite heater, and penetrates from the side surface of the LaB6 or CeB6 crystal to the electron gun tip. You may provide the path | route which forms piping by and supplies an organic polymer. In addition, the reservoir may be installed in a PG graphite heater, and a path for supplying organic polymer may be provided by forming a pipe with a through hole from the LaB6 or CeB6 crystal side surface to the tip of the electron gun.

FIG. 13 is a diagram showing the crystal structure of lanthanum dicarbide. In the structure of this crystal, the work function is not necessarily 2.7 eV or less, which is the work function of LaB6. However, it is considered possible to reduce the work function by implanting and diffusing boron atoms as necessary.
However, it cannot be said that the degree of difficulty is simpler than the method of attaching and diffusing a carbon atom-containing material to LaB6 or CeB6 crystals as in the present invention.

As described above, according to the electron gun of the present invention, the electron gun cathode material is a material obtained by injecting and diffusing carbon atoms into a LaB6 or CeB6 crystal as an electron gun cathode material, and emits thermoelectrons. Therefore, by reducing the work function of 2.7 eV of LaB6 or CeB6 to 1.7 eV or less, the operating temperature of the electron gun could be lowered from 1600 ° C. to 1200 ° C. . At the same time, the luminance of 1 × 10 6 A / cm 2 steadian at 50 kV of conventional LaB6 or CeB6 could be increased 10 times or more. Due to the low-temperature operation, the oxidative consumption of the electron gun cathode material and the evaporation of the material itself can be sufficiently reduced, and a long-life electron gun having a lifetime of one year or more can be configured. Since the self-evaporation rate of LaB6 is 1/7 at 100 ° C., the self-evaporation rate due to a temperature drop of 400 ° C. is 1/400. The oxidation consumption rate of boron becomes almost 0 at a vacuum degree of 10 ⁻⁷ pascal.

  Since this electron gun stably emits electrons, an electron gun suitable for a multi-electron beam drawing apparatus can be realized.

  Therefore, the high-intensity long-life electron gun is a powerful means for realizing an electron beam drawing apparatus. Brain computer industry based on artificial intelligence and neuron imitation with micropatterns and autonomous driving cars, various robots, robots for working at dangerous places, robots for nursing care, interactive coexistence robots, large-scale buildings and large-scale construction quickly Robots that work, upload human consciousness, copy human memory consciousness, thinking process at that time, and then take over the human thinking method and memory and live consciously indefinitely have an infinite life In order to make the semiconductor industry such as artificial brain such as artificial brain into a huge industry, an electron beam drawing apparatus based on an electron gun makes a great contribution.

  This electron gun can be used as an electron gun for an X-ray generator. In that case, the current density is usually 400 ° C. lower than LaB6 and a current density of 10 times is possible, so the size of the bright spot of the X-ray generation light source is reduced to one third, and the lifetime becomes 2400 times. For this reason, in the X-ray apparatus, image sharpening and long life can be achieved. Accordingly, medical X-ray devices have made significant progress and contributed greatly to the development of the medical X-ray field.

  Similarly, when used at 1200 ° C. as an electron gun for an electron microscope, the market is developed as a general electron microscope with a long life and a large current density of 10 times or more. Although it is a special application, when the work function can be reduced to 1 eV, it can be used at 1600 ° C. and the current density can be increased 37,000 times. Since the resolution of the electron microscope is determined by the square root of the current density when the current value is the same, the beam size can be reduced to 1/192. Since the resolution of the current scanning electron microscope is about 2 nm, a resolution of 10 pm can be achieved.

  This means that, for example, the size of an oxygen atom is 120 pm, so that one oxygen atom can be recognized sufficiently. That is, it means that the scanning electron microscope using this electron gun can recognize the atomic images on the surface and their arrangement in an instant as an image. Of course, when only the surface is observed with sufficiently low acceleration and there are multiple atomic layers in the thickness direction, calculation of image processing to obtain an image of a desired cross-sectional atomic layer is required. The type of each atom can be identified by measuring Auger electrons and fluorescent X-rays of each atom. Therefore, it is revolutionary that the atomic arrangement structure of all observation objects can be separated and analyzed by image processing. Direct observation of what is actually happening at the atomic level is powerful in the field of medicine, biology, life phenomena, physics, chemistry, etc. It is obvious to do. For this reason, it is a great contribution to contribute to the advancement of human scientific progress in the fields of technological development and invention.

  The advantage of the present invention is that the work function can be reduced to 63% or less compared to LaB6 or CeB6, so that what was operating at 1600 ° C. can be lowered to 1200 ° C., and the brightness of the electron gun is 50 kV. There are two merits in that what is 106 A / cm 2 steradian can be increased to 107 A / cm 2 steradian. As a demerit, it can be considered that oxidative consumption due to oxidization due to residual oxygen in a vacuum increases. However, with respect to this point, it has been experimentally confirmed that boron and carbon have almost no difference in oxidizability, and oxidation exhaustion is not severe compared to LaB6 or CeB6. However, since there is oxidation consumption equivalent to LaB6 or CeB6, the degree of vacuum needs to be 1 × 10 −7 pascal or more. However, since the deterioration rate is not faster than that of a single LaB6 or CeB6, it can be said that the present invention has advantages and no disadvantages.

  In the course of the experiment, the inventors of the present invention formed a film by injecting and diffusing LaB6 or CeB6 and carbon atoms on a rhenium metal film to form an electron gun cathode material. Since it seems to be effective for lowering the work function, it will be understood by those skilled in the art that an electron gun cathode material in which a lanthanum atom and a carbon atom are directly bonded may be easily understood.

  It is also easy to replace low-electronegativity lanthanum or cerium with other low-electronegativity atoms such as calcium, strontium, barium, yttrium, and hafnium. Although a combination of LaB6 or CeB6 boron atoms and carbon atoms has been described, it is easily conceivable that the same effect can be obtained even if the number of boron atoms on the side of the atom having high electronegativity is changed. Further, it can easily be considered that the same effect can be obtained by mixing or combining a nitrogen atom or an oxygen atom in addition to a boron atom and a carbon atom on the side of an atom having high electronegativity.

  Although rhenium that uses a refractory metal substrate and does not chemically react with LaB6 has been described as the electron gun substrate, if the work temperature is reduced to 1200 ° C. or lower, not only rhenium but also tungsten, niobium, It is considered that metals such as titanium, iron, nickel, cobalt, hafnium, tantalum, molybdenum, iridium, and platinum can be used as the refractory metal substrate.

  Although a PG (pyrolytic graphite) heater made of carbon is used for heating the electron gun, other heaters may be used as long as equivalent heating can be performed. A heater made of an alloy such as rhenium tungsten may also be used.

  In the description of the present invention, the electron gun is used for a thermionic emission electron gun, but it is easy to apply a strong electric field to the tip of the electron gun and use it as a heating type field emission electron gun (Schottky electron gun). Can be realized.

  As for the application of the electron gun in the present invention, mention has been made of an electron beam drawing apparatus, particularly a multi-column one, but in addition, an electron beam inspection and length measuring apparatus, an electron beam transmission microscope, a scanning electron microscope (SEM) and It can be easily considered that it can be applied to these multi-columns. The above is added.

DESCRIPTION OF SYMBOLS 101 Ceramic disc 102a, 102b High heat-resistant spring-like metal 103 LaB6 or CeB6 single crystal 104a, 104b PG (pyrolytic graphite) heater 105 Wehnelt electrode 106 Organic polymer 107 Contour line 108 showing potential by Wehnelt Equipotential line near anode 109 Anode 110 Emission Electron due to Thermoelectron Emission 111 Irradiation Distribution of Emission Electron due to Thermoelectron Emission 201 Boron Atom 202 Lanthanum Atom 301 Carbon Atom 401 Organic Polymer Example 501 Hydrogen Atom 601 Electrons 602, 603 ejected toward vacuum 604 Electrons 701 emitted outside the vacuum 701 Electrons 702 and 703 emitted toward the vacuum 801 Electrons emitted outside the vacuum 801 LaB6 or CeB6 single crystal pre-use shape 802 LaB6 Is a shape after use of CeB6 single crystal 803 Rectangular aperture 804 Rectangular aperture overlapping portion 805 Rectangular aperture 806 Electron density distribution function 807 Electron density distribution function 901 after 700 hours Low work function cathode material 902 Rhenium substrate 903 Supply of low work function cathode material Source 1001 Low work function cathode material 1002 Rhenium substrate 1003 Low work function cathode material source 1101 Electron gun cathode substrate 1102 Organic polymer 1201 Electron gun cathode substrate 1202 Organic polymer 1301 Lanthanum atom 1302 Carbon atom

Claims (13)

  An electron gun comprising a cathode material in which lanthanum or cerium atoms, carbon atoms, and boron atoms are bonded at a predetermined adjacent distance.   2. The electron gun according to claim 1, wherein the cathode material is a LaB6 or CeB6 crystal surface coated with a solution containing carbon atoms, and carbon atoms are diffused in the crystal. An electron gun according to claim 2,
The electron gun is characterized in that the cathode material is formed by applying an organic polymer on the crystal surface of LaB6 or CeB6 and injecting and diffusing carbon atoms into the LaB6 or CeB6 crystal at a predetermined temperature. The electron gun according to claim 3,
An electron gun characterized in that the organic polymer has a chain of hydrocarbon chains. An electron gun according to claim 4, wherein
An electron gun characterized in that the organic polymer has a chain of hydrocarbon chains and is bonded with alcohol, glycol or glycerin. The electron gun according to claim 5,
An electron gun, wherein the organic polymer is a fatty acid glyceride esterified with a chain of hydrocarbon chains and glycol or glycerin.   4. The electron gun according to claim 3, wherein the organic polymer has a benzene ring.   2. The electron gun according to claim 1, wherein the cathode material is obtained by ion-implanting carbon atoms into a crystal of LaB6 or CeB6.   2. The electron gun according to claim 1, wherein the cathode material is a LaB6 or CeB6 crystal, in which carbon atoms are sputtered and diffused.   2. The electron gun according to claim 1, wherein the cathode material is formed by adhering carbon atoms to a LaB6 or CeB6 crystal by vapor deposition and diffusing.   2. The electron gun according to claim 1, wherein the cathode material is obtained by injecting and diffusing carbon atoms into LaB6 or CeB6 crystals using methane, ethane, or propane gas. 2. The electron gun according to claim 1, wherein the cathode material is formed by injecting and diffusing carbon atoms into a LaB6 or CeB6 crystal attached on a rhenium substrate. An electron gun according to any one of claims 1 to 12,
An electron gun having a work function of a cathode material of 1.7 eV or less.