JP2008091270A - Contamination removal method for throttle device in charged particle beam device and contamination removal device for aperture device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To remove contaminations such as carbon in a throttle device without requiring replacement or cleaning of the aperture device. <P>SOLUTION: In order to remove contaminations, such as, carbon deposited inside the aperture device provided inside a charged particle beam device, fluorine compound gas is poured into the aperture device. As a result, it is possible to remove contaminations deposited inside the aperture device. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a contour of carbon or the like that contaminates a diaphragm device by irradiation of a charged particle beam such as an electron beam in a charged particle beam device such as a scanning or transmission electron microscope, a semiconductor inspection device, an electron beam drawing device, or a semiconductor manufacturing device. The present invention relates to a method and an apparatus for removing a nation.

  In charged particle beam equipment such as scanning or transmission electron microscopes, semiconductor inspection equipment, electron beam lithography equipment, and semiconductor manufacturing equipment, hydrocarbon substances are decomposed by electron beams inside the sample chamber (vacuum chamber), which is a vacuum equipment. Then, it is deposited on a sample, a sample stage, a diaphragm device, etc. in the apparatus. This is generally called contamination.

  In a charged particle beam apparatus using a charged particle beam, contamination on a sample due to irradiation of a charged particle beam such as an electron beam has been a problem. For example, contamination adheres to the periphery of the opening of a diaphragm device such as a movable diaphragm device. In particular, when contamination is unevenly adhered to the periphery of the opening, charge-up (charging) may occur, and the shape of a charged particle beam such as an electron beam may change.

  Therefore, the throttling device is periodically replaced, cleaned as described in Patent Document 1 and Patent Document 2, for example, or cooled by liquid nitrogen as shown in paragraphs 0019 to 0020 of Patent Document 3. The cooling plate was arranged around the expansion device and functioned as a trap part, and residual gas around the opening of the expansion device was removed to trap contamination.

Further, for example, as shown in Patent Document 4, oxygen in the atmosphere is converted into active oxygen by plasma and introduced into the sample chamber, and is attached to the inner wall of the sample chamber, the stage member, and the sample surface itself. There is also a technique in which contamination can be removed by causing a chemical action between oxygen and active oxygen, generating CO, CO ₂ , and H ₂ 0 and evacuating them.

  In addition, for example, as shown in Patent Document 5, a sample exchange chamber that can be selected for connection to and isolation from the air atmosphere, and a connection and isolation for sample exchange chamber can be selected to perform length measurement, processing, analysis, observation, etc. There are known electron microscopes and the like that are provided with sample exchange chambers that can be connected / isolated to each of the sample chambers, and that have means for evacuating the interior of each sample exchange chamber. A gas is introduced into the sample exchange chamber by a gas introduction means, and as shown in paragraph 0079 of Patent Document 5, as a specific example of the gas, a gas containing a hydrocarbon that causes contamination and having a relatively large mass (Patent Document) If the gas for reducing contamination is H, He, B, etc. having a mass smaller than that of C, the gas for reducing contamination is CmHn (m and n are natural numbers). More types of gases are conceivable, such as H, B, C, N, O, F, etc. It is described that this gas is ideally an inert gas (He, Ne, Ar, Kr, Xe, Rn) that hardly reacts with other substances.

  Further, as shown in the latter part of paragraph 0018 of Patent Document 6 and paragraph 0010 of Patent Document 7, there is a technique for reducing contamination using an inert gas such as nitrogen gas or helium gas.

  For example, as shown in paragraphs 0008 and 0019 of Patent Document 8, in a semiconductor manufacturing apparatus, for example, nitrogen gas for diluting a processing residue is diluted in the reaction chamber in order to prevent contamination when the reaction chamber is opened to the atmosphere. Techniques for supplying indoors are well known.

  Further, for example, as shown in the claims of Patent Document 9 and the description of the examples (especially, the second page, upper right column, line 6 to the lower left column, line 11 of Patent Document 9, see FIG. 2). A technique for forming a noble metal thin film of platinum, platinum-palladium, gold, gold-palladium or the like on the diaphragm plate by ion sputtering coating or the like for the purpose of imparting conductivity to the diaphragm plate surface of the diaphragm device is also known.

  Similarly, in Patent Document 10, there is also known a technique capable of ion-coating a conductive material and gold on a diaphragm plate and cleaning a dirty diaphragm plate to a complete state.

  Further, for example, as shown in the claims of Patent Document 11 and paragraphs 0012 to 0016, it is described that the diaphragm plate is coated with an amorphous thin film such as osmium tetroxide having good conductivity. Describes that problems such as charging, contamination, and coating peeling are reduced.

Further, as a method for removing contamination, for example, a conductive thin film diaphragm plate is disposed in the claims of Patent Document 2, a diaphragm receiver is connected to an insulating material, a heating body is incorporated in the insulator, and a thin film diaphragm is incorporated. For example, in Patent Document 5, paragraph 0044, a sample holder and a sample fixing arm placed on a sample holder fixing position are heated at all times or regularly by a heater, For example, in Patent Document 1, the second page, upper right column, line 19 to the same document, the same page, lower left column, line 13 is described to remove hydrocarbons that cause contamination.
It is described that an electron beam is irradiated to the objective lens stop, and excess electrons are absorbed by the objective lens stop and the like, the temperature of the objective lens stop is increased, and contamination (contamination) of the objective lens stop is removed. Moreover, in Patent Document 12, paragraph 0016, the objective aperture, the electron detector, and the walls in the objective lens are made of a substance having a photocatalytic action, and a light source 14F and a light source 14G are installed to irradiate light to cause a photocatalytic reaction. It is described that contamination can be removed.
JP 63-76250 A Japanese Patent Laid-Open No. 3-105834 JP-A-8-31359 JP-A-1-105451 Japanese Patent Laid-Open No. 9-63527 Japanese Patent No. 3723846 JP-A-8-335449 JP-A-9-330859 JP-A-4-206244 JP-A-62-184749 Japanese Patent No. 3117687 Japanese Patent No. 3047293

  However, in the aperture devices of Patent Documents 1 to 3, it takes time and labor for replacement and cleaning, and a cooling device for the trap part must be provided, which hinders the original specimen observation and inspection work. The manufacturing cost is high, and there is a possibility that the apparatus becomes large.

  Further, in Patent Document 4, when active oxygen is introduced, a high temperature or a large amount of oxygen must be introduced, and damage is caused to a member disposed in the sample chamber.

  In addition, in the case of H, He, B, C, N, O, F, and other inert gases (Ne, Ar, Kr, Xe, Rn) as shown in Patent Document 5, the efficiency of the chemical reaction with the hydrocarbon system And the removal efficiency of hydrocarbons is low.

  Further, when the non-volatile lubricant remains in the vacuum chamber of the sample chamber, it cannot be removed efficiently with active oxygen. Furthermore, active oxygen causes a large damage to members inside the vacuum apparatus.

  Furthermore, even if the platinum, platinum palladium, etc. in Patent Documents 9 and 10 are coated, there is a problem that they are easily heated by irradiation with a charged particle beam such as an electron beam and are easily peeled off.

  In addition, when coating an amorphous thin film such as osmium tetroxide of Patent Document 11, osmium tetroxide as a coating material is expensive, and platinum, platinum palladium, etc. disclosed in Patent Documents 9 and 10 are the same as the coating technology. The aperture device must be taken out from the charged particle beam device, washed with carbon, etc., and coated with a film forming device such as a vacuum vapor deposition device, and the process work is complicated.

  Further, as a method for removing contamination, the method of irradiating the objective lens diaphragm with an electron beam of Patent Document 1 and heating it to remove it, or the method of Patent Document 12 irradiating and removing the object diaphragm made of a substance having a photocatalytic action. In the method, the substance constituting the aperture device is limited to a substance having a high electrical resistivity or a substance having a photocatalytic action, and, as described above, fluorine molecules do not spread into a complicated multi-layer structure with contamination. For this reason, it is necessary to spend time until the contamination is completely removed, resulting in a reduction in work efficiency.

  Therefore, in order to solve the above-described problems, the present invention does not require replacement or cleaning of the aperture device, or a new device / equipment, and can eliminate contamination such as carbon in the aperture device. It is an object of the present invention to provide a method for removing contamination from a diaphragm device and a device therefor.

  Another object of the present invention is to provide a method for removing contamination from a diaphragm in a charged particle beam apparatus and an apparatus therefor that can prevent the diaphragm from being contaminated by contamination such as carbon. .

  In order to solve the above-described problems, the present invention is characterized by matters described in the claims.

  According to the present invention, it is not necessary to replace or clean the throttling device. Furthermore, contamination such as carbon adhering to the expansion device can be removed without requiring a new device or equipment that causes high costs.

Further, for example, a single molecule of a fluorine compound such as WF ₆ is laminated on the surface of the aperture device to form a monomolecular film (coat), and the aperture device can be coated with the fluorine compound at the same time. Thus, maintenance is not required, the period of use is extended, and cost reduction associated with replacement can be achieved.

In general, the reaction with a fluorine compound-based gas is gentle, and the generated fluorine radical (F ⁻ ) (free radical) reacts reliably, so that the removal efficiency of the hydrocarbon-based gas is high. Further, even when the non-volatile lubricant remains in the apparatus, it can be removed more efficiently than active oxygen. Further, damage to members inside the apparatus is relatively small as compared with active oxygen. Furthermore, since the purge is performed a plurality of times with a very dilute fluorine compound-based gas, contamination can be removed efficiently and without damage even in a complicated and complicated structure.

Therefore, there is little damage to the surface of the throttle device and the inside of the device, and contamination can be efficiently removed by conventional hydrocarbon gases.

  Embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 schematically shows a diaphragm device and its related parts provided inside a charged particle beam device according to one embodiment of the present invention.

For example, a lens barrel 1 of a scanning electron microscope, a movable diaphragm device 2, a tank 3, a valve 4 and a nozzle 9 for injecting a fluorine compound gas (eg, ClF ₃ ) into the lens barrel 1 are shown.

  As shown in FIG. 2, the aperture device 2 is a movable aperture that moves in and out of the lens barrel 1. The diaphragm device 2 is not limited to this and may be a fixed diaphragm device.

The fluorine compound-based gas is not limited to ClF ₃ , for example, and other gases such as HF and XeF ₂ may be used.

  When a charged particle beam such as an electron beam is irradiated from an electron gun (not shown) or the like and passes through the opening 2a of the diaphragm device 2, carbon is nonuniformly formed in the opening 2a of the diaphragm device 2 as shown in FIG. Contamination 5 which is a contaminant such as adheres. In that case, charging (charging) may occur, and the shape of the beam may change, or the beam position on the sample surface (not shown) may change.

  Moreover, as shown in FIG. 4, the contamination 5 may adhere to the inside of the opening 2a of the diaphragm device in a raised manner.

Normally, an inert gas such as N ₂ is filled in the lens barrel 1 through the valve 4 from the direction of the arrow. Fluorine radicals generated by operating the valve 4 in place of an inert gas such as N ₂ and injecting a fluorine compound-based gas (for example, ClF ₃ ) from the tank 3 through the valve 4 into the lens barrel 1. Since (F ⁻ ) (free radical) reliably reacts with hydrocarbons, the removal efficiency of hydrocarbons is high. The expansion device 2 efficiently removes the contamination 5 when heated.

In particular, in the case of ClF ₃ , fluorine radicals (F ⁻ ) are generated by heat, and it becomes possible to selectively remove the contamination 5 only around the heated opening 2a.

Further, when a fluorine compound gas (for example, HF, NF ₃ , SiF ₄ , XeF _2, etc.) is injected into the lens barrel 1, fluorine radicals (F ⁻ ) are generated without heating the expansion device 2. In this case, it is not necessary to heat the expansion device 2, and the contamination 5 can be removed.

  Further, when introducing the fluorine compound-based gas, purging is performed a plurality of times. For example, purging is performed with a fluorine compound-based gas 2-3 times.

  This is because, when slight contamination occurs on the sample, excessive purge gas is not introduced into the device by repeating contamination removal with a very dilute fluorine compound gas multiple times. It is possible to eliminate damage as much as possible and reduce contamination more effectively.

  It is desirable to pay attention to handling etc. according to the molecular weight, boiling point, melting point, and other characteristics of each fluorine compound gas.

As another embodiment of the present invention, when fluorine compound-based gas (for example, SiF ₄ or WF ₆ ) is injected into the inside of the lens barrel 1, contamination 5 such as carbon adhering to the expansion device 2 is removed. .

Further, as shown in FIG. 5A, when fluorine compound-based gas WF ₆ is injected into the inside of the lens barrel 1, tungsten is deposited on the contamination 5, and the tungsten conductive coating (film formation). 6 is formed on the surface of the contamination 5 such as carbon, and charging (charging) can be prevented.

  As shown in FIG. 5B, tungsten is laminated as a single molecule on the surface of the contamination 5 such as carbon to form a single molecule coat (film formation) 7. Therefore, tungsten adheres to the surface of the contamination 5 densely, and charging (charging) can be reliably prevented.

  As another modification, as shown in FIG. 6A, the nozzle 8 from the fluorine compound gas tank 3 is steadily reached so that the fluorine compound gas reaches the opening 2a of the expansion device 2 steadily. May be extended to the vicinity of the opening 2a of the expansion device 2 and sprayed from the fluorine compound gas tank 3 through the valve 4 only to the vicinity of the opening 2a. The configuration of the entire apparatus is represented as shown in FIG.

  Further, as shown in FIG. 6B, for example, a plurality of nozzles 8 are provided at positions orthogonal to the moving direction of the expansion device 2, and a fluorine compound is provided only in the vicinity of the opening 2a of the expansion device 2 from the plurality of directions. System gas may be sprayed.

  Further, as shown in FIG. 8, an optical fiber 10 is provided in the vicinity of the opening 2a of the diaphragm device 2, light from the light source 11 is irradiated to the vicinity of the opening 2a of the diaphragm device 2, the diaphragm device 2 is heated, and contamination is caused. Nation can be chemically decomposed and removed. As the light from the light source, it is desirable to use far infrared rays of, for example, about 650 nm to 800 nm.

  Note that when the optical fiber 10 is passed through the inside of the lens barrel 1, vacuum sealing is performed.

  Further, as shown in FIG. 9, a condenser lens 12 is disposed inside the lens barrel 1, and a condenser lens 13 is disposed outside the lens barrel 1, and light from the light source 11 passes through a window member 14 to open the aperture of the diaphragm device 2. The diaphragm device 2 may be heated by irradiating near 2a.

  Note that the periphery of the window member 14 and the boundary between the lens barrel 1 are vacuum-sealed.

  As described above, it is possible to reliably avoid contamination of carbon or the like on the opening 2a of the expansion device 2. As a result, it is not necessary to replace the diaphragm device. The life of the throttle device is extended. Therefore, the maintenance and replacement time is extended, and the cost can be reduced.

1 shows a part of a charged particle beam device according to one embodiment of the present invention, in particular, a lens barrel, a diaphragm device, and a fluorine compound-based gas tank. A movable diaphragm device is shown. The figure which expanded the opening part of the aperture_diaphragm | restriction apparatus shown in FIGS. Sectional drawing which expanded the opening part of the aperture_diaphragm | restriction apparatus shown in FIG. A state in which a tungsten coating (film) is coated on the surface of contamination such as carbon is shown. (A) (B) shows the modification of this invention which sprays a fluorine compound type gas directly on the opening part of an aperture_diaphragm | restriction apparatus. 6 shows a modification of the present invention in which FIG. 6A is shown in more detail as the configuration of the entire apparatus. An example of the heating method of the opening part of a diaphragm | throttle device is shown. Another example of the heating method of the opening of the expansion device will be shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lens tube 2 Diaphragm apparatus 2a Opening part of diaphragm apparatus 3 Tank 4 Valve 5 Contamination 6 Conductive coat 7 Monomolecular coat 8 Nozzle 9 Nozzle

Claims (13)

  In order to remove contamination such as carbon adhering to the diaphragm provided inside the charged particle beam device, the fluorine compound-based gas is poured into the diaphragm and the contamination adhering to the diaphragm is removed. A method for removing contamination from a diaphragm of a charged particle beam device.   In order to remove contamination such as carbon adhering to the diaphragm provided inside the charged particle beam apparatus, the fluorine compound gas is poured into the diaphragm and the diaphragm is heated to remove the contamination. A method for removing contamination from a diaphragm of a charged particle beam device.   In order to prevent contamination such as carbon from adhering to the diaphragm provided inside the charged particle beam apparatus, a fluorine compound-based gas is poured into the diaphragm to form a fluorine compound coating on the diaphragm, A contamination removal method for a diaphragm of a charged particle beam device, wherein the contamination is removed so that the contamination does not directly adhere to the diaphragm. In the contamination removal method of the diaphragm | throttle device in the charged particle beam apparatus of any one of Claim 1, 2, 3,
The method for removing contamination of a diaphragm of a charged particle beam device, wherein the fluorine compound gas is HF, ClF ₃ , NF ₃ , SiF ₄ , WF ₆ , or XeF ₂ . In the contamination removal method of the diaphragm | throttle device of the charged particle beam apparatus of Claim 2,
The method for heating a diaphragm device is a method for removing contamination from a diaphragm device of a charged particle beam device, wherein the diaphragm device is irradiated with light and absorbed to generate heat.
_{4. The} method for removing contamination of a diaphragm of a charged particle beam device according to claim 3, wherein the fluorine compound coated on the diaphragm is HF, ClF ₃ , NF ₃ , SiF ₄ , WF ₆ , or XeF _2. A method for removing contamination from a diaphragm of a charged particle beam device.   7. The method for removing contamination in a diaphragm of a charged particle beam device according to claim 1, wherein the contamination is removed by purging the interior of the charged particle beam device with a fluorine compound gas a plurality of times. A method for removing contamination from a diaphragm of a charged particle beam device.   In order to remove carbon and other contaminants adhering to the aperture device provided inside the charged particle beam device, gas supply means for supplying a fluorine compound-based gas is provided inside the charged particle beam device, and the aperture device includes fluorine gas. A contamination removing device for a charged particle beam device squeezing device, characterized by pouring a compound-based gas to remove the squeezing device contamination.   9. A contamination removal apparatus for an aperture device of a charged particle beam device according to claim 8, wherein the aperture device is provided with light irradiation means for irradiating light, and the aperture device is heated to remove the contamination of the aperture device. A contamination removal device for a diaphragm of a charged particle beam device.   In order to prevent the contamination of carbon or the like from adhering to the diaphragm provided inside the charged particle beam apparatus, a gas supply means for supplying a fluorine compound-based gas is provided inside the charged particle beam apparatus. A decontamination device for an aperture device of a charged particle beam device, wherein a fluorine compound-based gas is poured into the aperture device to form a fluorine compound coating on the aperture device to remove the contamination on the aperture device. In the contamination removal apparatus of the diaphragm | throttle device of the charged particle beam apparatus of Claim 8 or 9,
The contamination removing device for a diaphragm of a charged particle beam device, wherein the fluorine compound gas is HF, ClF ₃ , NF ₃ , SiF ₄ , WF ₆ , or XeF ₂ . In the contamination removal apparatus of the diaphragm | throttle device of a charged particle beam apparatus of Claim 10,
A contamination removing device for a diaphragm of a charged particle beam device, wherein the fluorine compound to be coated on the diaphragm is SiF ₄ or WF ₆ . The contamination removal apparatus of the iris of the charged particle beam apparatus according to any one of claims 8 to 12, further comprising a gas introduction apparatus for introducing a fluorine compound gas, wherein the inside of the charged particle beam apparatus is a fluorine compound. A contamination removal device for an aperture device of a charged particle beam device, characterized by purging a plurality of times with a system gas.

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