JP6548179B1 - Electron gun - Google Patents

Abstract

An object of the present invention is to achieve high brightness and long life of an electron gun. The present invention relates to an electron gun using an electron gun cathode material 105 mainly based on LaB6 or CeB6. Methane gas or ethane gas is allowed to flow into the vacuum chamber holding the electron gun cathode material 105 so as to have a vacuum partial pressure of 1 × 10 −4 pascal or less, and is heated in a temperature range of 1000 ° C. to 1500 ° C. [Selection] Figure 1

Description

  The present invention relates to an electron gun used for an electron beam drawing apparatus and the like.

  In semiconductor lithography technology, conventionally, photolithography (optical lithography) has been mainly used 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. In the optical lithography technology, from the principle that the resolution improves by shortening the wavelength of light, the wavelength of light is shortened with the progress of miniaturization, and g-line (wavelength 436 nm) to i-line (wavelength 365 nm) It has been changed and has been miniaturized, highly integrated, and cost-reduced. Currently, excimer laser light with a wavelength of 193 nm is used. In the future, lithography techniques using 13.4 nm ultrashort ultraviolet light with a short wavelength have been developed.

  On the other hand, as for masks, development costs have been increasing with the progress of miniaturization of semiconductors, and the number of masks per LSI chip has reached several hundred million yen. Electron beam lithography systems have been used for mask development because of their features having a pattern generation function. However, processing time increases with the progress of photolithography technology, such as the introduction of super resolution technology that achieves transferability below the wavelength of light, and enlargement of mask data due to high integration, and the number per mask layer It takes ten hours.

  The electron beam drawing method has been developed from a method called single stroke writing with a finely narrowed electron beam, and a drawing method such as a method called collective drawing of several square microns called variable rectangular method. However, with the current variable rectangular beam, the vertical width and the horizontal width of the variable rectangular beam that can be used are getting smaller in synchronization with the recent miniaturization of the mask pattern. For this reason, the number of shots is accelerated at an accelerating rate, and it takes 200 hours (eight days) or more per mask.

  Therefore, maskless lithography technology that achieves direct drawing on a wafer by an electron beam drawing apparatus without using an expensive mask for the purpose of suppressing the increase in mask price through shortening of mask drawing processing time is attracting attention As a result, a multi-beam type apparatus has been proposed which performs drawing processing in parallel using a plurality of electron beams, and it is expected to increase the processing capacity to several tens of times or more.

In the maskless lithography technology, an industrially useful throughput is required to process at least 10 wafers of 300 mm diameter per hour. For this purpose, it is required to realize a multi-electron beam drawing apparatus using about 100 electron beams, from the processing capacity per electron beam. Therefore, in order to generate 100 (10 × 10) electron beams on a 300 mm wafer, a technique for generating a plurality of electron beams simultaneously at a pitch of 30 mm or less is required. Simultaneously generating an electron beam at 30mm pitch below, the electric field adjacent the electron gun cathode influence each other between the electron gun cathode, the size of the electron gun cathode is desirably 20mm or less.

  The throughput of the electron beam writing apparatus is proportional to the electron beam intensity and inversely proportional to the sensitivity of the resist as the photosensitive material. In the electron beam drawing apparatus, since the beam is blurred by a large current due to the interaction between electrons, 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 the intended drawing accuracy can not be obtained unless using an extremely fine (15 nm to 10 nm line width) LSI pattern with a low sensitivity resist (about 100 μC / cm ² ). Due to these limitations, a 300 mm wafer of approximately 600 cm ² is calculated to require a drawing time of 60,000 seconds or more. With approximately 100 multi-columns, this can be reduced to 600 seconds or less.

As the electron gun cathode of such an electron beam drawing apparatus, what has been conventionally used is a thermionic emission electron gun cathode of LaB ₆ or CeB _{6 in} the shape of a truncated cone. The diameter of the truncated cone portion of the tip was 50 μmφ, and the inclination angle of the truncated cone was about 60 degrees. The electron gun cathode was used after heating at about 1600 ° C. under a vacuum of 1 × 10 ⁻⁶ pascal or higher. The luminance at this time was 1 × 10 ⁷ A / cm ² steradian at 50 kV, and the luminance was quite large, but at 1600 ° C., 70 μm / 700 hours (one month) was consumed by sublimation of LaB ₆ or CeB ₆ There has occurred. Therefore, although the diameter of the truncated conical portion at the tip is initially 50 μm is sharpened from 10 μm to 20 μm, the luminance is further increased but the irradiation uniformity is degraded. That is, since only a narrow range is irradiated uniformly, the pattern accuracy is degraded. For this reason, the life of the electron gun cathode using LaB ₆ or CeB ₆ is only about one month, and it is basically insufficient in an electron beam writing apparatus which usually needs a half to one year life. For this purpose, there has also been a system using a turret electron gun cathode unit or the like capable of rotating and exchanging 10 LaB ₆ or CeB ₆ electron gun cathodes .

However, even with the turret electron gun cathode unit capable of rotating and exchanging the 10 LaB ₆ or CeB ₆ electron gun cathodes described in the preceding paragraph, the major problem is that the shape of the tip changes more and more according to the use time of the electron gun cathode. Met.

Under such circumstances, there has been a need in the industry for an electron gun simultaneously having a luminance several tens times higher than that of conventional LaB ₆ or CeB ₆ and a long life of six months or more.

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

Electronics and Ion Beam Handbook 3rd Edition Editor's Chairperson, 132nd Committee of Japan Society for the Promotion of Science Katsumi Ura The Nikkan Kogyo Shimbun, October 28, 1998 P119 Figure 4.

  At the same time, high brightness and long life of the electron gun are established.

The electron gun according to the present invention uses a thermionic emission material based on LaB ₆ or CeB ₆ to heat methane gas or ethane gas into the inside of the electron gun chamber in a vacuum state in the state of heating and emitting thermions. The electron gun is characterized in that a flow rate at a gas partial pressure of 1 × 10 ^-4 pascal or less is used. By this, a large emission current can be obtained continuously. Although the principle of why such a large emission current can be obtained will be described later and will not be described in detail here, an electron gun with high brightness can be obtained.

When a hydrocarbon-based gas is flowed through LaB ₆ or CeB ₆ and heated to 1000 ° C. to 1500 ° C., an emission current of 30 to 100 times the amount of emitted electrons without flowing the gas can be obtained. Hydrocarbon-based gases include methane, ethane, propane and butane. It is experimentally found that the effect of increasing the emission current value of LaB ₆ when flowing into the electron gun chamber is a property common to the four types of gases.

However, with propane gas, a gas partial pressure of 4 × 10 ⁻⁴ pascal or more is required. Butane requires a gas partial pressure of at least 1 × 10 ⁻³ pascal. Although the cause is unknown, since there is a rough proportionality between the gas partial pressure and the evaporation amount of LaB ₆ or CeB ₆ , these gases increase the evaporation amount of LaB ₆ or CeB ₆ and the life of the electron gun Propane gas or butane gas having 3 or 4 carbon atoms is inappropriate because Therefore, although methane gas which can lower the partial pressure is optimum as the hydrocarbon gas, ethane gas can be sufficiently used.

  According to the present invention, it is possible to simultaneously achieve high brightness and long life of the electron gun.

It is a figure shown about 1 of embodiment of this invention. It is a figure which shows the state which put gas in the electron gun of this invention. It is a figure shown about 2 of embodiment of this invention. It is operation | movement explanatory drawing of Embodiment 1 of a micro gas flow rate control mechanism. It is operation | movement explanatory drawing of Embodiment 2 of a micro gas flow rate control mechanism. It is principle explanatory drawing of the emission current increase in this embodiment. It is 2 of principle explanatory drawing of the emission current increase in this embodiment. It is explanatory drawing of a rhenium cover electron gun.

  A mode (embodiment) for carrying out the present invention will be described with reference to the drawings.

"Features of the embodiment"
In electron beam lithography technology used in the lithography field for drawing circuit patterns in semiconductor (LSI) manufacturing processes, high-intensity, long-life, high-intensity, high-temperature thermionic emission current of thermionic gun to dramatically increase processing capacity Enables the realization of electron guns. At present, the electron beam lithography system needs a multi-column electron beam lithography system equipped with a large number of electron guns in order to speed up the processing speed. It is desirable to maximize the product of brightness and life.

In order for the electron gun cathode to have high brightness, it is necessary for the so-called work function to be small or the Richardson-Dashman coefficient to be large. The work function is a value representing the energy for emitting electrons from inside the substance into a vacuum in eV. The smaller this value is, the easier it is to emit electrons.
The Richardson-Dashman coefficient indicates the electron generation efficiency of the electron emission surface, and the larger this value, the larger the electron emission. The balance between the two maximizes the emission current. In the present embodiment, it is mainly intended that the work function is not reduced but the Richardson-Dashman coefficient is increased dramatically.

Since the LaB ₆ or CeB ₆ electron gun cathode used conventionally has a small Richardson-Dashman coefficient of about 100, when used at high brightness, it is necessary to raise the temperature to around 1600 ° C. for use. The amount of evaporation was large and the life was only about 700 hours. For use near 1600 ° C., there is an evaporation of about 0.1 μm in one hour, and in 700 hours corresponding to about one month, the evaporation is 70 μm. For this reason, in the conventional electron gun cathode with the tip of LaB ₆ in a truncated cone with an angle of 60 degrees and the tip plane being a circular flat surface with a diameter of 50 μm for applying high voltage electric field, the tip when used at 1600 ° C for 700 hours The tip surface is reduced in diameter, and the tip portion is lowered in height due to the loss, and it becomes difficult to apply a high voltage electric field for emitting electrons. In this embodiment, since the Richardson-Dashman coefficient is 30 to 100 times that of the conventional one, the temperature can be set to 1000 ° C. to 1500 ° C. and can be used 100 ° C. to 500 ° C. lower than 1600 ° C. It is as small as one-tenth to one-hundredth, and the life is stable as long as about six months even with high luminance. The temperature is particularly preferably in the range of 1300 ° C. to 1400 ° C. In that case, the temperature can be lowered by 200 to 300 ° C. as compared with the conventional case.

"Configuration of embodiment"
In the following description, the description of methane gas and ethane gas is almost the same, so only methane gas will be described, but methane gas and ethane gas are almost similar in the embodiment and the effect. Although LaB ₆ and CeB ₆ description will be given only in LaB ₆ in order to be substantially similar, LaB ₆ and CeB ₆ in the embodiment and the effect is substantially the same.

FIG. 1 is a view for explaining 1 of the embodiment of the electron gun of the present embodiment.
Methane gas is supplied from a methane gas cylinder 101 either instantaneously or continuously. Methane gas passes through the gas pressure regulator 102 to the vacuum chamber 108 (a downstream vacuum chamber having a higher gas partial pressure than the electron gun cathode chamber side) connected to the electron gun cathode chamber using the micro gas flow rate control mechanism 103. It is made to flow. When an electron strikes methane gas in a state where an emission electron current is emitted from the electron gun cathode , the methane gas is ionized to be ionized to become an ion called CH ₄ ⁺ or CH ₃ ⁺ . This ion is a cathode. react with LaB ₆ hit the cathode. The amount of gas supplied may be increased as the amount of electron emission from the electron gun cathode increases.

LaB ₆ has crystals of boron and lanthanum. The hydrogen atom in the hydrocarbon CH ₄ ⁺ or CH ₃ ⁺ reacts with the boron atom and evaporates in vacuum in the form of monoborane BH ₃ or diborane B ₂ H ₆ . Consequently LaB ₆ boron lattice of the crystalline near-surface is deposited on the LaB ₆ crystal surface lanthanum atoms to break becomes a droplet, the deposited state.

  The remaining carbon atoms in the above reaction are taken into the lanthanum atom droplet layer, and the carbon atoms strongly bond the lanthanum atoms together. The lanthanum atom has a melting point of 920 ° C. and has a finite vapor pressure at 1200 ° C. or higher, so it tries to evaporate into a vacuum, but the carbon atoms combine the lanthanum atoms, so the evaporation rate is remarkable It's getting lower.

Referring back to FIG. 1, the vacuum chamber is separated into an electron gun cathode chamber 106 by a partition 104b and a vacuum chamber 108 adjacent to the electron gun cathode chamber, and a vacuum comprising an electron lens and a deflector of an electron beam drawing apparatus by a partition 104a. The vacuum chamber of the chamber 109 is separated. The partition 104b is formed with a central microhole at a position facing the tip of the electron gun cathode material 105, and a central microhole is also formed in a portion corresponding to the partition 104a, whereby the tip of the electron gun cathode material 105 is formed. An emission electron stream (electron beam 111) from the part is emitted downward. Methane gas enters the vacuum chamber 108, passes through the central fine hole of about 1 mm in the partition wall 104b, and enters the electron gun cathode chamber 106.

Electron gun cathode material 105 consisting of LaB ₆ crystal is disposed on the center axis in the electron gun cathode chamber 106. The electron gun cathode chamber 106 is evacuated by a turbo molecular pump 107a. The vacuum chamber 108 adjacent to the electron gun cathode chamber 106 is evacuated by the turbo molecular pump 107 b. The electron beam 111 sequentially passes through three vacuum chambers: an electron gun cathode chamber 106, a vacuum chamber 108, and a vacuum chamber 109. The electron beam 111 is converged and deflected in a vacuum chamber 109 containing an electrostatic deflector 112 and an electromagnetic lens or magnetic field deflector 113 and used for drawing. The vacuum chamber 109 is evacuated by the turbo molecular pump 107 c. The three turbo molecular pumps 107 a, 107 b and 107 c are evacuated by the roughing pump 110.

  With a predetermined negative voltage applied to the electron gun cathode material 105, the temperature of the electron gun cathode material 105 is maintained at 1000 ° C. to 1500 ° C. As a result, an electron (thermoelectron) beam is emitted from the electron gun cathode material 105.

FIG. 2 is a view showing a state in which gas is introduced into the electron gun of the present embodiment. The methane gas 202 introduced into the vacuum chamber 108 is ionized by the electron beam 201 to be CH ₄ ⁺ and CH ₃ ⁺ . The ions 203 are attracted toward the electron gun cathode because the electron gun cathode material 105 has a negative potential.

FIG. 3 is a view showing 2 of the embodiment. In this figure, one oxygen gas cylinder system is added as compared to the first embodiment. That is, the flow rate and partial pressure of the oxygen that has come out of the oxygen gas cylinder 301 are finely adjusted through the gas pressure regulator 302 and the fine gas flow rate control mechanism 303. The reason for using methane gas and oxygen gas together is to strengthen the bonding force of the lanthanum atom droplet layer. In addition, it is preferable to flow the oxygen gas together with methane gas or ethane gas realistically or continuously at a flow rate such that the internal gas partial pressure is 2 × 10 ⁻⁵ pascal or less. Further, these gas flow rates are preferably changed in accordance with the amount of electrons emitted from the electron gun cathode material 105. That is, it is preferable to increase the amount of gas as the amount of emitted electrons is larger.

  FIG. 4 shows one of the embodiments of the micro gas flow rate control mechanism 103. The gas 401 flowing into the minute gas flow rate control mechanism passes through only the minute gas flow path 402 having a length of L with a minute opening having the minimum cross-sectional area S0 and becomes the gas 406 flowing out of the minute gas flow rate control mechanism . Here, the minimum cross-sectional area S0 of the micro gas flow channel 402 is 30 square μm, and the length L is 20 mm. 403 in the figure is shut off by a drive valve 408 which shuts off or passes the flow rate of the fine opening 403 driven by an electrical signal. Similarly, 404 in the figure is shut off by a drive valve 409 which shuts off or passes the flow rate of the fine opening 404 driven by the electrical signal. Similarly, 405 in the figure is shut off by a drive valve 410 which shuts off or passes the flow rate of the fine opening 405 driven by an electrical signal.

  The cross-sectional area of the micro-aperture of 403 in the figure is 60 square μm, the cross-sectional area of the micro-aperture of 404 is 120 square μm, and the cross-sectional area of the micro-aperture of 405 is 240 square μm. By this, the four micro aperture cross-sections from 0 to 450 square μm can be 1x, 2x, 3x, 4x, 5x, 6x, 7x, 8x, 9x, 10x every 30 square μm Since it is possible to select 16 kinds of flow rates from 11 times, 12 times, 13 times, 14 times and 15 times, the minute flow rate can be electrically controlled. Here, the length of all the micro flow channels is common L = 20 mm. In the upper part of 4 in the figure, the total cross-sectional area of the fine channels through which methane gas can flow is 30 square μm. In the lower part of FIG. 4, the total area of fine channels through which methane gas can flow is 210 square μm. Thus, in FIG. 4, it is possible to select a flow rate which is an integral multiple of 30 square μm, that is, an integral multiple expressed in binary number.

  FIG. 5 is an operation explanatory view of Embodiment 2 of the minute gas flow rate control mechanism. Points different from the first embodiment will be described. The fine channels 501 to 510 all have the same cross-sectional area S0, the length of the channels is L = 20 mm, and the flow rates of all the gas channels are equal. In the figure, reference numeral 511 denotes an electrically active translational drive valve, which is completely shut off when all the flow paths are shut off. Assuming that the minimum flow rate is 1, 10 flow rates can be controlled from 1 to 1 unit. It is the state of the valve 512 by the translational drive that can pass a flow rate seven times the unit flow rate. Microflow channels 501 to 507 are made to pass gas (gas), and 512 are translational drive valves that shut off all the microflow channels 508 to 510.

FIG. 6 is a diagram for explaining the principle of increasing the emission current in the present embodiment. Normal LaB ₆ crystal 601 to form a lattice crystal octahedron of six boron atoms electronegativity 2.04 constituted the single spatial cube 8. One lanthanum atom exists at the center of this lattice crystal. The electronegativity of the lanthanum atom is 1.1. Since the larger the electronegativity, the more electrons are attracted, and the lanthanum atom passes the electrons to the surrounding boron to easily have a positive charge and to emit thermionic electrons. However, because of the presence of a crystal lattice of boron, the Richardson-Dashman coefficient, which is the ease of emission of electrons viewed in plan from the end face, remains at about 80 to 100. If only droplets of lanthanum atoms are used, it is predicted that the Richardson-Dashman coefficient will be several dozen times to about 100 times larger. We boron crystal lattice of the LaB ₆ crystal by the action of methane gas was completely destroyed LaB ₆ crystal, lanthanum droplet is experimentally confirmed to become exposed. We also experimentally confirm that this improves the Richardson-Dashman coefficient by about 100 times.

What the methane molecule 606 is ionized is attracted to the LaB ₆ crystal 601, and the boron atom reacts with the hydrogen atom in the methane gas and disperses in the vacuum as monoborane 607 and diborane 608. This in LaB ₆ boron crystal lattice near the surface of the crystal is destroyed, lanthanum droplet is exposed. This is the 602, lanthanum droplets 602 deposited from LaB ₆ crystal is the same as the 609 adhering to the surface of the LaB _6. Next, excess carbon atoms stay in the lanthanum atom droplets to strengthen the bonding between the lanthanum atoms and to strengthen the bonding to the LaB ₆ crystal surface. This is 610 in the figure and is identical to 603 in the figure.

Further, the introduction of oxygen atoms strengthens the bonding ability in the lanthanum atom droplet. Therefore, oxygen molecules 611 are introduced into the electron gun cathode chamber 106, absorbed in the lanthanum atom droplet layer, and the bonding force between the lanthanum atoms is enhanced, and the oxygen atom and the carbon atom cooperate to form the lanthanum atom droplet layer on the LaB ₆ crystal surface. It is fixed. This is illustrated at 612 and 604 in the figure.

FIG. 7 is a second explanatory view of the principle of increasing the emission current according to this embodiment. Focusing on the tip of the electron gun cathode material 105, methane gas ions 704 destroy the crystal lattice due to boron atoms on the surface of the LaB ₆ crystal 701, and the lanthanum atom droplets are exposed. In this lanthanum atom 702 droplet layer, the bond strength between the lanthanum atoms is enhanced by the carbon atom 703. In addition, the adhesion to the LaB ₆ crystal also becomes strong. This emission current will have a 100 times stronger than normal LaB _6.

FIG. 8 is an explanatory view of a rhenium-covered electron gun. Since LaB ₆ evaporates from the entire normal LaB ₆ crystal, it is deposited on PG (pyrolytic graphite) heaters 803a, 803b and the heater resistance decreases with time, and the temperature gradually increases with time if constant current is kept flowing. It gets lower. Therefore, as LaB ₆ crystal is not deposited directly heater, rhenium cover 802 configured with rhenium which is a refractory metal which does not react directly with LaB ₆ covers the LaB ₆ crystal. That is, the rhenium cover 802 covers a portion other than the substantial tip portion (the portion from which electrons are emitted ) of the electron gun cathode material. Further, side surfaces and the bottom surface of the LaB ₆ crystal such thermal electrons are emitted only from the tip of the LaB ₆ crystal is covered by back cover 805 made from rhenium cover 802 and rhenium. Reference numerals 804 a and 804 b denote holding tools, which are provided on the ceramic disk 806. This embodiment can also be used as shown in FIG. 8, in which case the main object is achieved only with the tip of the LaB ₆ crystal 801. That is, a significant increase in emission current occurs only at the tip side of the LaB ₆ crystal 801 and on the tip side wall slightly visible. This reaction does not occur on most of the cylindrical side surface of the LaB ₆ crystal 801 coated on the rhenium cover 802 Nor.

The electron gun cathode can be generally used in an electron beam drawing apparatus to stably emit electrons with high brightness and long life. In addition, since it is possible to achieve a life of 6 months or more without exchanging the electron gun cathode , it is possible to realize an electron gun suitable for a multi electron beam drawing apparatus. In addition, since a life of 6 months or more can be secured even when used at a low degree of vacuum, it can also be used for an X-ray source electron gun operated at a low degree of vacuum. In addition, if the diameter of the axis is 10 μm or less, it can be used as an electron gun for a high brightness long life scanning electron microscope or a transmission electron microscope. In addition, since a low degree of vacuum can be used, a three-dimensional electron beam welding machine using an electron beam can also be used as an electron gun.
In addition, the tip of the electron gun cathode may be sharpened, and it is also preferable to use it in a drawing apparatus for an ultrafine pattern or an observation electron microscope.

  As described above, since the high intensity and long life are achieved as the electron gun, the electron gun according to the present embodiment includes an electron beam drawing device, an electron beam microscope, an electron beam inspection device, an X-ray generator, etc. We will make a great contribution to the electron beam applied equipment industry in general.

In the electron beam drawing apparatus, it is necessary to increase the luminance 10 times or more than that of the conventional LaB ₆ or CeB ₆ electron gun cathode from one electron gun. A luminance of 10 ⁷ A / cm ² steradian at 50 kV is required. For this purpose, it is necessary to use the conventional LaB ₆ or CeB ₆ electron gun cathode that has been used at a normal operating temperature of 1500 ° C. by raising the temperature to 1600 ° C. In this case, the life of the electron gun cathode is shortened, and it is sublimed to about 70 μm in one month and consumed. For this purpose, the vacuum chamber was leaked to the atmosphere about once a month, and it was necessary to replace the electron gun cathode . However, in 1 of the present embodiment, methane gas was flowed at 1 × 10 ⁻⁵ pascal and the use temperature was set to 1200 ° C., and a high luminance equivalent to 1600 ° C. of the LaB ₆ crystal was usually obtained. From this, it was found that high brightness and a life of 6 months can be achieved.

  In the conventional electron gun, a maintenance time of 1 day per month is required for maintenance of the electron beam drawing apparatus, but with the electron gun of the present invention, the maintenance time can be 1 day per 6 months. It can be done cheaply.

  By multi-columning and multi-beaming this, it is possible to miniaturize semiconductor production of 10 nm to 5 nm. Furthermore, the brain-type computer industry and automatic driving vehicles based on artificial intelligence and neuron imitation having fine patterns by increasing the degree of integration, various robots, robots for working at dangerous places, robots for nursing care, interactive coexistence robots, large-scale buildings And robots that work large-scale work quickly, upload human consciousness, copy human's memory awareness at that time, thinking process, and from that point on consciously infinite living on that human thinking method and memory It can be used to build a semiconductor industry that will be a huge industry of artificial intelligence in the future, such as an immortal artificial brain with life.

  In addition, the electron gun of the present embodiment can also be used for an X-ray radiation apparatus, and exerts great power as an electron gun for all X-rays as an electron gun with high brightness and large current and long life. The X-ray radiation device has a very large market for a device for detecting dangerous goods in transportation and a medical diagnostic application for diagnosing cancer, cerebral hemorrhage, cerebral infarction and the like. As described above, the electron gun of the present embodiment contributes as a core of a large industry of 5 trillion yen or more.

101 Methane gas cylinder 102 Gas pressure regulator 103 Micro gas flow rate control mechanism 104a, 104b Vacuum chamber partition plate 105 Electron gun cathode material 106 Electron gun cathode chamber 107a, 107b, 107c, Turbo molecular pump 108 Vacuum chamber adjacent to electron gun cathode chamber 109 Vacuum chamber 110 equipped with electron lens and deflector of electron beam writing apparatus Roughing pump 111 Electron beam 112 Electrostatic deflector 113 Electron lens or electromagnetic deflector 201 Emitted electron beam 202 Methane gas or ethane gas 203 Methane gas or ethane gas CH ₄ ⁺ or CH ₃ ^{+ with} ions formed by decomposition
301 Oxygen gas cylinder 302 Gas pressure regulator 303 Micro gas flow rate adjustment mechanism 401 Flow of gas flowing into micro gas flow rate control mechanism 402 Micro opening having a minimum cross sectional area S0 and a micro flow passage 403 having a length L A minimum cross sectional area S0 The fine channel 404 with a length L having a fine opening twice as large as the fine channel with a length L of 4 having a minimum cross-sectional area S0 The fine channel 405 with a length L with a micro-opening 8 times a minimum cross-sectional area S0 The minute flow path 406 having a length of L. The gas flow 407 discharged from the minute gas flow rate control mechanism. The electric valve 407 which shuts off or passes the flow of the minute opening 402 driven by the electric signal. Drive valve 409 for blocking or passing the flow rate of the fine opening 403 Drive valve for shutting off or passing the flow rate of the fine opening 404 driven by the electrical signal 10 Drive valve 411 which shuts off or passes the flow rate of the fine opening 405 driven by electrical signal Flow rate of the fine opening 403 driven by the electrical signal. Drive valve 413 which shuts off or passes through the flow of the fine opening 404 driven by the electric signal. Drive valve 414 shuts down or passes through the flow of the fine opening 405 driven by the electric signal. A fine channel having a length of L and a fine channel having a length L A fine channel having a minimum cross-sectional area S0 and a length L having a micro channel 503 A fine opening having a minimum cross-sectional area S0 and a length of L Channel 504 A fine channel having a minimum cross-sectional area S0 and a length L of a micro-channel 505 a minimum cross-sectional area S A fine channel having a length of L with a fine opening 506 A fine channel having a minimum cross sectional area S0 with a length of L 507 A fine opening with a minimum cross sectional area S0 with a length of L Flow channel 508 A fine opening having a minimum cross-sectional area S0 and a fine flow channel 509 having a length L A fine opening having a minimum cross-sectional area S0 a fine flow channel 510 having a length L A fine opening having a minimum cross-sectional area S0 The micro-flow passage 511 is a valve by translational drive with a length of L, and the micro-flow passage 501 is a valve by translational drive valve 512 that allows gas to pass and shuts off all the microflow passages 502 to 510 from the passage 501 to 507 passed through the gas, translational drive valve 601 to shut off all 510 micro channel from 508 LaB ₆ crystal 602 LaB lanthanum droplet layer 603 on ₆ crystal LaB ₆ Koh on crystal How carbon atoms atoms droplet layer is a carbon atom and an oxygen atom in state 604 LaB ₆ lanthanum droplets layer on the crystal bonded to each other lanthanum each other are bonded to each other lanthanum atoms with each other 605 LaB ₆ crystal 606 methane molecule 607 monoborane 608 diborane 609 LaB ₆ crystal's boron lattice reacts with hydrogen atoms to form monoborane / diborane and evaporates to destroy the boron lattice, so lanthanum atoms deposited on the surface of LaB ₆ crystal Droplet layer 610 A state in which carbon atoms mutually connect lanthanum atoms in the lanthanum atomic droplet layer on the LaB ₆ crystal 611 oxygen molecules 612 oxygen molecules collide with the lanthanum atomic droplet layer and are decomposed into oxygen atoms A carbon atom and an oxygen atom mutually connecting a lanthanum atom 701 LaB ₆ crystal 702 a lanthanum atom 70 3 carbon atoms 704 CH ₄ ⁺ ions 801 LaB ₆ crystals consisting of circular cylinders with different radiuses Rhenium cover 802 rhenium cover 803a, 803b PG (pyrolytic graphite) heater 804a, 804b holding tool 805 LaB ₆ crystal fixed to rhenium cover Female screw 806 ceramic disk with back cover made of rhenium

Claims (7)

Heat pressing the electron gun cathode material containing LaB ₆ or CeB _6, in the electron gun which emits thermal electrons from an electron gun cathode material,
In the vacuum chamber connected to the electron gun cathode chamber where the temperature of the electron gun cathode material is maintained at 1000 ° C. to 1500 ° C. and the electron gun cathode material in a vacuum, methane gas or ethane gas is used. the following flow 1 × 10 -4 ^pascal to prn or continuously, and the flow, in a state where methane gas or ethane gas is introduced into the electron gun chamber,
Electron gun An electron gun characterized by emitting thermoelectrons from a cathode material . The electron gun according to claim 1, wherein
The methane gas or ethane gas is allowed to flow in from the downstream vacuum chamber side connected to the electron gun chamber by the fine opening facing the electron gun cathode material and the gas partial pressure is higher than the electron gun chamber side, An electron gun characterized by applying a potential and making methane gas or ethane gas an ion having a positive charge by the emission current from the tip of the electron gun cathode material to make it easy to combine with the electron gun cathode material. The electron gun according to claim 1, wherein
Flowing the electron gun cathode material at a temperature in the range of 1000 ° C. to 1500 ° C. together with methane gas or ethane gas either realistically or continuously, at a flow rate such that the gas partial pressure inside the vacuum is 2 × 10 ⁻⁵ pascal or less Electron gun characterized by The electron gun according to claim 1, wherein
The tip portion emitting electrons is made of a metal that covers most of the surface other than the substantial tip portion viewed from the electron emission surface side, and the cover does not directly react with the electron gun cathode material LaB ₆ or CeB ₆ An electron gun characterized by comprising a high melting point metal. The electron gun according to claim 4,
An electron gun characterized in that the refractory metal constituting the cover is rhenium. The electron gun according to claim 1, wherein
An electron gun characterized by changing a partial pressure of gas flowing inside an electron gun chamber according to an electron emission amount of the electron gun. 7. The electron gun according to any one of claims 1 to 6 , wherein the boron atomic lattice near the surface of the original LaB ₆ or CeB ₆ crystal is destroyed with methane gas or ethane gas, and the lanthanum atom droplet Alternatively, a cerium atom droplet is deposited on the surface of the LaB ₆ or CeB ₆ crystal, and the temperature is raised above the melting point of the lanthanum atom or the cerium atom using carbon atom or oxygen atom or both carbon atom and oxygen atom. Electrons characterized by strongly bonding lanthanum atoms or cerium atoms to each other and strongly attaching them to the surface of LaB ₆ or CeB ₆ crystals and emitting emission current while suppressing evaporation. gun.