Cleaning system and cold field emission equipment

Abstract

The invention provides a cleaning system which is applied to cold field emission equipment, the cold field emission equipment comprises a vacuum cavity and a cold field emission electron source, a lamp filament of the cold field emission electron source is located in the vacuum cavity, and the cleaning system comprises a baking unit which is arranged in the vacuum cavity and used for heating the lamp filament, removing impurities on the surface of the lamp filament; and the cooling unit is arranged outside the vacuum cavity and is used for cooling the vacuum cavity and the lamp filament after the impurities on the surface of the lamp filament are removed. The cleaning system provided by the invention can be used for efficiently cleaning the filament of the cold field emission electron source.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor technology, and in particular to a cleaning system and a cold field emission device. BACKGROUND

[0002] The electron beam detection device is mainly used for detecting the performance and defects of a wafer or a photomask in a semiconductor manufacturing process. The detection method of the electron beam detection device is to use an electron beam to scan a wafer or a photomask to be detected to obtain an image of secondary electron imaging of the wafer or the photomask, and to find abnormal points in the image through computer vision technology.

[0003] The electron beam detection device can include various types of electron sources, such as a thermionic cathode electron source, a Schottky electron source, or a cold field emission (CFE) electron source. The disadvantage of the cold field emission technology is the lack of stability and reliability, because the electron source filament is at room temperature in the working state, compared with the traditional hot field emission electron source using high temperature (> 1500 degrees Celsius) to protect the filament. The filament of the electron source is easily contaminated by gas atoms adhering to the filament tip, thereby blocking electron emission, causing the overall performance of the electron source to rapidly decline, and eventually leading to failure. Therefore, it is necessary to build a cleaning system to ensure that the CFE electron source can work normally. SUMMARY

[0004] The present application provides a cleaning system and a cold field emission device, which can efficiently clean the filament of the CFE electron source and improve the overall reliability and stability of the CFE electron source.

[0005] In a first aspect, a cleaning system is provided, which is applied to a cold field emission device, the cold field emission device comprising a vacuum cavity and a cold field emission electron source, a filament of the cold field emission electron source being located in the vacuum cavity, the cleaning system comprising: a baking unit arranged in the vacuum cavity and used for heating the filament to remove impurities on the surface of the filament; and a cooling unit arranged outside the vacuum cavity and used for cooling the vacuum cavity and the filament after the impurities on the surface of the filament are removed.

[0006] The present application provides a cleaning system, which can clean the filament of the electron source in situ in a vacuum environment, without disassembling the electron source, and can immediately cool the vacuum cavity and the filament through the cooling unit after removing the impurities on the surface of the filament to return to the working state. The cleaning system provided by the present application can clean the filament of the electron source in situ while shortening the cleaning time as much as possible, and improve the overall reliability and stability of the electron source.

[0007] The filament of the cold field emission electron source is used for emitting an electron beam to detect the performance and defects of a wafer or a photomask.

[0008] The impurities on the filament surface can be some gas atoms and / or volatile organic compounds. The baking unit can heat the filament to remove the impurities on the filament surface.

[0009] Since the cold field emission electron source works at room temperature, the vacuum chamber and the filament can be cooled by the cooling unit after the impurities on the filament surface are removed.

[0010] In combination with the first aspect, in some implementations of the first aspect, the baking unit includes an infrared lamp, a resistance wire, an electron beam bombardment device, or an electron gun.

[0011] The infrared radiation generated by the infrared lamp can directly act on the filament without the need for air as a heat transfer medium. When the light of the infrared lamp is not blocked from shining on the filament, the infrared radiation can be absorbed by the filament, increasing the molecular vibration of the filament and thereby generating heat to remove the impurities attached to the filament. The resistance wire can release heat radiation for heat transfer, and heat is transferred to the filament by heat radiation, thereby achieving the effect of heating and cleaning. The resistance wire can also be embedded in the lamp holder of the cold field emission electron source and physically contact the filament to transfer heat to the filament, thereby achieving the effect of heating and cleaning. The electron beam bombardment device mainly cleans by electron beam bombardment, including installing a magnetic field module in the CFE electron source or making the electron beam emit 180 degrees after being turned by an electromagnetic field, and then bombarding the position where the filament is located to cause local high temperature of the filament, thereby achieving the effect of cleaning the filament. The electron gun can release high-intensity current to the filament in the form of arcing, thereby causing local high temperature of the filament in a very short time, thereby achieving the effect of cleaning the filament.

[0012] The present application provides a cleaning system that can clean the filament of the electron source in situ in a vacuum environment and provides a variety of baking units for heating the filament, thereby improving the selectability of the cleaning system.

[0013] In combination with the first aspect, in some implementations of the first aspect, the cleaning system includes a plurality of the baking units, and the plurality of the baking units are uniformly distributed around the filament with the filament as the center.

[0014] For example, the plurality of baking units can be arranged on the inner wall of the vacuum chamber and uniformly distributed around the filament with the filament as the center. In other possible implementations, the plurality of baking units can be arranged on the first part of the lamp holder of the cold field emission device, the first part protruding into the vacuum chamber and the filament being fixed on the first part.

[0015] The application provides a cleaning system, which adopts a design of multiple baking units arranged in an array, so that all areas in the vacuum cavity are covered by radiation, baking blind spots are eliminated, and heat energy can be focused on the filament to uniformly heat the filament and improve cleaning efficiency.

[0016] In some implementations of the first aspect, the number of the baking units in the cleaning system is 2-10.

[0017] In some implementations of the first aspect, the power of the baking unit is 100 W-1000 W.

[0018] In some implementations of the first aspect, the distance between the baking unit and the filament is 10 mm-100 mm.

[0019] In some implementations of the first aspect, the cooling unit comprises a forced air cooling device or a liquid cooling device.

[0020] In some implementations of the first aspect, the cold field emission electron source comprises a lamp holder and the filament, the lamp holder comprises a first part protruding into the vacuum cavity and a second part connected with the first part, the second part is arranged on the outer wall of the vacuum cavity and encloses the vacuum cavity together with the outer wall of the vacuum cavity, and the filament is fixed on the first part.

[0021] In some implementations of the first aspect, the cooling unit is arranged on the outer wall of the vacuum cavity, or the cooling unit is arranged in the lamp holder, or the cooling unit is arranged on the outer wall of the vacuum cavity and in the lamp holder at the same time.

[0022] For example, the cooling unit can be arranged on the inner wall of the lamp holder, and since the lamp holder is connected with the filament, the cooling unit can rapidly cool the filament after the impurities are removed, and the temperature in the vacuum cavity is lowered at the same time.

[0023] For example, the cooling unit can be arranged on the outer wall of the vacuum cavity, and the cooling unit can rapidly cool the temperature in the vacuum cavity after the impurities are removed, and the temperature of the filament is lowered at the same time.

[0024] For example, the baking unit is arranged on the inner wall of the first position of the vacuum cavity, and the cooling unit is arranged on the outer wall of the first position of the vacuum cavity, that is, the baking unit and the cooling unit are arranged in a "back-to-back" manner through the cavity wall of the vacuum cavity. In this way, after the impurities of the filament are removed and the baking unit stops working, the cooling unit can directly cool the baking unit, and then cool the vacuum cavity and the filament, so that the cooling efficiency is improved and the overall cleaning time is shortened.

[0025] When the cooling unit is arranged on the outer wall of the vacuum chamber and in the lamp holder at the same time, the cooling efficiency can be maximized, and the overall cooling time, i.e., the overall cleaning time, can be shortened, and the overall reliability and stability of the electron source can be improved.

[0026] The present application provides a cleaning system, and the cooling unit can be arranged on the outer wall of the vacuum chamber and / or in the lamp holder, the cooling efficiency is improved, the overall cooling time, i.e., the overall cleaning time, is shortened, and the overall reliability and stability of the electron source are improved.

[0027] In combination with the first aspect, in some implementations of the first aspect, the cleaning system includes a plurality of the cooling units, the plurality of the cooling units are uniformly distributed on the outer wall of the vacuum chamber, or the plurality of the cooling units are uniformly distributed in the lamp holder, or the plurality of the cooling units are uniformly distributed on the outer wall of the vacuum chamber and in the lamp holder at the same time.

[0028] The present application provides a cleaning system, and the cooling unit can be uniformly arranged on the outer wall of the vacuum chamber and / or in the lamp holder, the cooling efficiency is improved, the overall cooling time, i.e., the overall cleaning time, is shortened, and the overall reliability and stability of the electron source are improved.

[0029] In combination with the first aspect, in some implementations of the first aspect, the cold field emission device further includes a mechanical pump exhaust port, a molecular pump exhaust port, and an ion pump exhaust port, the mechanical pump exhaust port is used to reduce the air pressure in the vacuum chamber to 10E-1 Pa, the molecular pump exhaust port is used to maintain the vacuum degree in the vacuum chamber between 10E-8 Pa and 10E-1 Pa, and the ion pump exhaust port is used to maintain the vacuum degree in the vacuum chamber between 10E-10 Pa and 10E-8 Pa.

[0030] The process of heating and cleaning the filament using the baking unit releases gas, and therefore, after the cooling is completed, the vacuum degree in the vacuum chamber can be restored to a state meeting the working requirements of the electron source by using the ion pump.

[0031] The second aspect provides a cold field emission device, including a vacuum chamber, a cold field emission electron source, and the cleaning system in the first aspect and any one of the possible implementations of the first aspect, the filament of the cold field emission electron source is located in the vacuum chamber, and the cleaning system is used to remove impurities on the surface of the filament of the cold field emission electron source and to cool the vacuum chamber and the filament. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a comparison diagram of a traditional hot field emission technology and a cold field emission technology provided by the embodiments of the present application.

[0033] Figure 2is a structural schematic diagram of a cold field emission device provided by an embodiment of the present application.

[0034] Figure 3 is a connection structure schematic diagram of a lamp holder and a vacuum cavity provided by an embodiment of the present application.

[0035] Figure 4 is a schematic diagram of a cleaning system provided by an embodiment of the present application.

[0036] Figure 5 is a schematic diagram of another cleaning system provided by an embodiment of the present application.

[0037] Figure 6 is a schematic diagram of an arrangement of a baking unit in an electron beam detection device provided by an embodiment of the present application.

[0038] Figure 7 is a schematic diagram of an arrangement of a cooling unit in an electron beam detection device provided by an embodiment of the present application.

[0039] Figure 8 is an exemplary flowchart of a cleaning method provided by an embodiment of the present application.

[0040] Figure 9 is a schematic diagram of an application scenario of a cleaning system provided by an embodiment of the present application.

[0041] Figure 10 is a schematic diagram of an infrared lamp provided by an embodiment of the present application.

[0042] Figure 11 is a schematic diagram of a change of a filament temperature in a cleaning process provided by an embodiment of the present application.

[0043] Figure 12 is an exemplary flowchart of another cleaning method provided by an embodiment of the present application.

[0044] Figure 13 is an exemplary flowchart of another cleaning method provided by an embodiment of the present application.

[0045] Figure 14 is an exemplary flowchart of another cleaning method provided by an embodiment of the present application.

[0046] Figure 15 is an exemplary flowchart of another cleaning method provided by an embodiment of the present application. DETAILED DESCRIPTION

[0047] With reference to the drawings, a description will now be given of the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort should fall within the scope of the present application.

[0048] In the present application, the words "example" and "for example" are used to illustrate, exemplify, and / or clarify a point. Any embodiment or design scheme described in the present application as "example" should not be interpreted as being more preferred or having more advantages than other embodiments or design schemes. Rather, the word "example" is used to present the concept in a specific manner.

[0049] The business scenarios described in the embodiments of the present application are used to more clearly illustrate the technical solutions of the embodiments of the present application, and do not constitute a limitation on the technical solutions provided by the embodiments of the present application. A person of ordinary skill in the art can know that, as new business scenarios appear, the technical solutions provided by the embodiments of the present application are also applicable to similar technical problems.

[0050] In the present application, the words "example" and "for example" are used to illustrate, exemplify, and / or clarify a point. Any embodiment or design scheme described in the present application as "example" should not be interpreted as being more preferred or having more advantages than other embodiments or design schemes. Rather, the word "example" is used to present the concept in a specific manner.

[0051] In the present application, "at least one" means one or more, and "multiple" means two or more. The "and / or" describes the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the following three cases: A exists alone, A and B exist together, and B exists alone, where A and B can be singular or plural. The character " / " generally represents an "or" relationship between the associated objects. "At least one of the following" or similar expressions means any combination of these items, including any combination of single or multiple items. For example, at least one of a, b, or c can represent a, b, c, a-b, a-c, b-c, or a-b-c, where a, b, and c can be single or multiple.

[0052] The semiconductor inspection equipment is mainly used for detecting the performance and defects of wafers or masks in the semiconductor manufacturing process, and is throughout the entire semiconductor production process. In a broad sense, the semiconductor inspection equipment can be divided into front-end testing equipment and back-end testing equipment according to the testing link. The semiconductor inspection equipment for front-end detection can include a scanning electron microscope, a transmission electron microscope and an electron beam inspection (EBI) device, etc. Among them, the electron beam inspection device can detect physical defects of wafers or masks by emitting an electron beam. The physical defects can include particles, impurities, cracks and the like on the wafers or masks. The detection method of the electron beam inspection device is to scan the wafer or mask to be detected by using an electron beam to obtain the image of the secondary electron imaging of the wafer or mask, and to find out the abnormal points in the image by using computer vision technology.

[0053] Various types of electron sources can be included in the electron beam inspection device, such as thermionic cathode electron sources, Schottky electron sources or cold field emission (CFE) electron sources, etc. The CFE electron source is an electron source based on cold field emission technology, which can also be called a cold source.

[0054] Figure 1 It is a comparison diagram of a conventional hot field emission technology and a cold field emission technology provided by an embodiment of the present application.

[0055] The cold field emission electron source has a very high beam current density and a very small beam spot. The high beam current density means high imaging brightness and fast scanning speed. The small beam spot means high imaging resolution.

[0056] The cold field emission technology is one of the most advanced technologies in the field of electron beams. Compared with similar technologies, it has stronger focusing ability and higher beam current density. Its performance advantages come from the following principles: 1. The low energy divergence of the cold field emission electron source can improve the resolution of the electron beam device; 2. Due to the small virtual source size, the brightness of the cold field emission electron source is much higher than that of other electron sources; 3. The brightness of the cold field emission electron source is three orders of magnitude higher than that of the thermionic emitter, and one order of magnitude higher than that of the Schottky emitter.

[0057] The electron beam detection equipment based on cold field emission technology can provide high imaging resolution and high scanning rate, which is its core competitiveness. The disadvantage of cold field emission technology is the lack of stability and reliability, because the electron source filament is at room temperature in working state, compared with the traditional hot field emission electron source which uses high temperature (> 1500 degrees Celsius) to protect the filament, the filament of the electron source is easily contaminated by gas, such as gas atoms adhering to the filament tip, thereby blocking electron emission, causing the overall performance of the electron source to decline rapidly, and eventually leading to failure. The filament material of the mainstream electron source, such as tungsten single crystal needle tip, will go through the following three stages during use: 1. First, the clean electron source enters the stable period with the adsorption of gas; 2. Then, with the further adsorption of gas, current noise gradually appears, enters the unstable period, and the stability of the electron source becomes poor; 3. With the increase of working time, the surface will gradually accumulate a layer of pollutants, and the emission current will start to fluctuate sharply, eventually leading to damage.

[0058] The embodiment of the present application provides a cleaning system which can be applied to the cold field emission electron source technology of semiconductor equipment, and can clean the electron source filament in situ without affecting the working state of the electron source. The in-situ cleaning in the embodiment of the present application includes two meanings: first, the electron source does not need to be taken out of the equipment and can be directly cleaned in the equipment; second, the ultra-high vacuum environment of the electron source and the temperature in the vacuum chamber are not affected by the in-situ cleaning, and the electron source can return to the normal working state immediately after cleaning.

[0059] Figure 2 is a structural schematic diagram of a cold field emission equipment provided by the embodiment of the present application.

[0060] The CFE equipment includes a vacuum chamber 110, a CFE electron source 120, a mechanical pumping pump 130, a molecular pumping pump 140 and an ion pumping pump 150. The filament 121 of the CFE electron source 120 is arranged inside the vacuum chamber 110, and the CFE electron source 120 includes the filament 121 and a lamp holder 122. The lamp holder 122 is used to fix the filament 121 inside the vacuum chamber 110. Figure 3 is a connection structure schematic diagram of a lamp holder and a vacuum chamber provided by the embodiment of the present application. The lamp holder 122 includes a first part 123 protruding into the vacuum chamber 110 and a second part 124 connected with the first part 123, the second part 124 is arranged on the outer wall of the vacuum chamber 110 and forms the vacuum chamber 110 together with the outer wall of the vacuum chamber 110. The filament 121 is fixed on the first part 123.

[0061] The filament 121 is used to emit an electron beam to detect physical defects of a wafer or a photomask to be detected. A mechanical pump 130, a molecular pump 140 and an ion pump 150 are arranged on the outer wall of the vacuum chamber 110 and communicate with the interior of the vacuum chamber 110, wherein the mechanical pump 130 is driven by a mechanical pump to reduce the air pressure in the vacuum chamber 110 from normal atmospheric pressure (10E 5 Pa) to 10E -1 Pa, the molecular pump 140 is driven by a molecular pump to maintain the vacuum degree in the vacuum chamber 110 between 10E -8 Pa and 10E -1 Pa, and the ion pump 150 is driven by an ion pump to maintain the vacuum degree in the vacuum chamber 110 between 10E -10 Pa and 10E -8 Pa.

[0062] Figure 4 is a schematic diagram of a cleaning system provided by an embodiment of the present application.

[0063] The cleaning system provided by the embodiment of the present application comprises at least one baking unit 210 and at least one cooling unit 220. The baking unit 210 is arranged in the vacuum chamber 110 and used to heat the filament 121 to remove impurities on the surface of the filament 121. The impurities can be some gas atoms and / or volatile organic compounds. The cooling unit 220 is arranged outside the vacuum chamber 110 and used to cool the vacuum chamber 110 and the filament 121 after the impurities on the surface of the filament 121 are removed.

[0064] As shown in Figure 4 , the baking unit 210 can be arranged on the inner wall of the vacuum chamber 110, or can be connected with the lamp holder 122 as shown in Figure 5 . Alternatively, the baking unit 210 can also be arranged inside the vacuum chamber 110 in other ways, as long as the baking range of the baking unit 210 can cover the filament 121. The specific arrangement of the baking unit 210 is not limited in the present application, for example, the baking unit 210 can be symmetrically distributed around the filament 121 inside the vacuum chamber 110. It should be understood that the more uniform the distribution of the baking unit 210 around the filament 121, the more uniform the heating of the filament 121, the higher the heating efficiency, and the faster the impurities are removed.

[0065] The baking unit 210 can be various types of heating devices, such as an infrared lamp, a resistance wire, an electron beam bombardment device, an electron gun, etc. The infrared lamp generates infrared radiation that can directly act on the filament 121 without the need for air as a heat transfer medium. When the light of the infrared lamp is not blocked from shining on the filament 121, the infrared radiation can be absorbed by the filament 121, causing the molecular vibration of the filament 121 to increase, thereby generating heat and removing impurities attached to the filament 121. The resistance wire can release heat radiation for heat transfer to the filament 121, thereby achieving the effect of heating and cleaning. The resistance wire can also be embedded in the lamp holder to physically contact the filament 121 and transfer heat to the filament 121, thereby achieving the effect of heating and cleaning. The electron beam bombardment device mainly cleans by means of electron beam bombardment, including installing a magnetic field module on the CFE electron source 120 or making the electron beam emit 180 degrees after being deflected by an electromagnetic field, and then bombarding the position where the filament 121 is located, causing local high temperature of the filament 121, thereby achieving the effect of cleaning the filament. The electron gun can release high-intensity current to the filament 121 in the form of arcing, thereby causing local high temperature of the filament 121 in a very short time, thereby achieving the effect of cleaning the filament.

[0066] The power of the baking unit 210 determines the upper limit of the baking temperature and the heating efficiency. In the embodiments of the present application, the power of the baking unit 210 can be set to be between 100 watts (W) and 1000 W, including 100 W and 1000 W. The distance between the baking unit 210 and the filament 121 determines the upper limit of the baking temperature. In the embodiments of the present application, the distance between the baking unit 210 and the filament can be set to be between 10 millimeters (mm) and 100 mm, including 10 mm and 100 mm. The array distribution design of the plurality of baking units 210 determines the uniformity of heating of the filament 121. In the embodiments of the present application, the number of baking units 210 can be set to be between 2 and 10. It should be understood that the above examples are only preferred cases, and the present application is not limited thereto, for example, only one baking unit 210 can also be provided.

[0067] After the filament 121 is heated and cleaned using the baking unit 210, the filament 121 and the vacuum chamber 110 need to be cooled to room temperature before they can work normally. At the same time, the process of heating and cleaning the filament 121 using the baking unit 210 releases gas, thereby causing the vacuum degree to decrease. Therefore, after cleaning is completed, the filament 121 needs to be cooled and then restored to a vacuum state that meets the working requirements. In order to shorten the time of the entire cleaning process, the embodiments of the present application cool the filament 121 and the vacuum chamber 110 by means of a cooling unit 220 in the cleaning system. The cooling unit 220 is arranged outside the vacuum chamber 110 and is used to reduce the temperature of the vacuum chamber 110 and the filament 121. The cooling unit 220 can be an air cooling device or a liquid cooling device.

[0068] Figure 6 is a schematic diagram of the arrangement of the baking units in the electron beam detection device provided by the embodiments of the present application, and the view angle of the schematic diagram is a bottom view, i.e. along a direction opposite to the electron beam emitting path.

[0069] The embodiments of the present application do not limit the number and specific positions of the baking units 210. The baking units 210 applied in the cleaning system of the electron beam detection device can be one or multiple. The baking units 210 are arranged inside the vacuum chamber 110, as long as the baking range of the baking units 210 can cover the filament 121. For example, Figure 6 As shown in (a) of FIG. 10, multiple baking units 210 are arranged at the bottom of the first part 123 of the lamp holder 122 close to the outer edge, and are uniformly distributed around the filament 121. For example, Figure 6 As shown in (b) of FIG. 10, multiple baking units 210 are arranged on the inner wall of the vacuum chamber 110, and are uniformly distributed around the filament 121. For example, Figure 6 As shown in (c) of FIG. 10, only one baking unit 210 is arranged on the inner wall of the vacuum chamber 110, and is used to heat the filament 121. For example, Figure 6 As shown in (d) of FIG. 10, only one baking unit 210 is arranged at the bottom of the first part 123 of the lamp holder 122 close to the outer edge, and is used to heat the filament 121. For example, Figure 6 As shown in (e) of FIG. 10, multiple baking units 210 are arranged at the bottom of the first part 123 of the lamp holder 122 close to the outer edge, and are unevenly distributed around the filament 121. For example, Figure 6 As shown in (f) of FIG. 10, multiple baking units 210 are arranged on the inner wall of the vacuum chamber 110, and are unevenly distributed around the filament 121. For example, Figure 6 As shown in (g) of FIG. 10, multiple baking units 210 are arranged at the bottom of the first part 123 of the lamp holder 122 close to the outer edge, and are uniformly distributed around the filament 121, and multiple baking units 210 are arranged on the inner wall of the vacuum chamber 110, and are uniformly distributed around the filament 121. For example, Figure 6 As shown in (h) of FIG. 10, multiple baking units 210 are arranged at the bottom of the first part 123 of the lamp holder 122 close to the outer edge, and are unevenly distributed around the filament 121, and multiple baking units 210 are arranged on the inner wall of the vacuum chamber 110, and are unevenly distributed around the filament 121. For example, Figure 6 As shown in (i) of FIG. 10, multiple baking units 210 are arranged between the lamp holder 122 and the inner wall of the vacuum chamber 110, for example, the multiple baking units 210 can be fixed between the lamp holder 122 and the inner wall of the vacuum chamber 110 through a support connected with the inner wall of the vacuum chamber 110.

[0070] Figure 7FIG. 1 is a schematic diagram of an electron beam inspection apparatus according to an embodiment of the present application. The schematic diagram is a perspective view of the electron beam inspection apparatus.

[0071] The number and specific locations of the cooling units 220 are not limited in the embodiments of the present application. The cooling units 220 applied in the cleaning system of the electron beam inspection apparatus can be one or more. The cooling units 220 are arranged outside the vacuum chamber 110 to cool the vacuum chamber 110 and the filament 121. For example, the cooling units 220 can be arranged only in the lamp holder 122, or the cooling units 220 can be arranged only on the outer wall of the vacuum chamber 110, or the cooling units 220 can be arranged both on the outer wall of the vacuum chamber 110 and in the lamp holder 122. As shown in (a) of FIG. 2, a plurality of cooling units 220 are uniformly arranged on the outer wall of the vacuum chamber 110, and a plurality of cooling units 220 are uniformly arranged on the inner wall of the lamp holder 122. As shown in (b) of FIG. 2, one cooling unit 220 is arranged on the outer wall of the vacuum chamber 110, and one cooling unit 220 is arranged on the inner wall of the lamp holder 122. As shown in (c) of FIG. 2, only one cooling unit 220 is arranged on the outer wall of the vacuum chamber 110. As shown in (d) of FIG. 2, only one cooling unit 220 is arranged on the inner wall of the lamp holder 122. As shown in (e) of FIG. 2, a plurality of cooling units 220 are unevenly arranged on the outer wall of the vacuum chamber 110, and a plurality of cooling units 220 are unevenly arranged on the inner wall of the lamp holder 122. As shown in (f) of FIG. 2, some cooling units 220 are arranged in the lamp holder 122, some cooling units 220 are arranged on the outer wall of the vacuum chamber 110, and some cooling units 220 are arranged close to the outer wall of the vacuum chamber 110. Figure 7 Figure 7 Figure 7 Figure 7 Figure 7 Figure 7

[0072] Figure 8 FIG. 5 is an exemplary flowchart of a cleaning method according to an embodiment of the present application.

[0073] 510, cleaning preparation.

[0074] For example, in the cleaning preparation stage, it is ensured that the baking unit 210 and the cooling unit 220 are well connected. The chamber door of the vacuum chamber 110 is closed, the vacuum chamber 110 enters a sealed state, the mechanical pump starts to operate, and the internal pressure of the vacuum chamber 110 is reduced from the normal atmospheric pressure (10E 5 Pa) to 10E -1 Pa. Figure 4 520, start in-situ cleaning.

[0075]

[0076] ​​​​​​​During startup, the molecular pump and ion pump are activated, and the vacuum level inside vacuum chamber 110 is approximately 10E-. 10 Pa. Filament 121 stops working, baking unit 210 and cooling unit 220 are turned off, and the temperature of filament 121 is at room temperature, for example, 22 degrees Celsius (295K).

[0077] 530, heating up for cleaning.

[0078] During the heating and cleaning phase, the molecular pump and ion pump are activated, and filament 121 stops working. Baking unit 210 is activated, and cooling unit 220 is deactivated. The temperature of filament 121 rises rapidly, releasing gas, and the vacuum level increases from 10E. -10 Pa changes to 10E -9 Pa.

[0079] In one application scenario, the baking unit 210 is an infrared lamp, and its distribution is as follows: Figure 6 As shown in (b), the temperature of filament 121 rises to no less than 200 degrees Celsius in less than 5 minutes and is maintained at that temperature for 15 minutes. Because the process of heating and cleaning filament 121 using baking unit 210 releases gas, the vacuum level decreases from 10E. -10 Pa changes to 10E -9 Pa.

[0080] In one application scenario, if the cooling unit 220 is simultaneously located on the outer wall of the vacuum chamber 110 and inside the lamp holder 122, such as Figure 7 As shown in (a), (b), (e), or (f), during the heating and cleaning phase, the cooling unit 220 located inside the lamp holder 122 can be turned off, while the cooling unit 220 located on the outer wall of the vacuum chamber 110 can be turned on. In this way, the filament 121 can be heated up rapidly while ensuring the cooling efficiency within the vacuum chamber 110.

[0081] 540, temperature drop.

[0082] During the cooling phase, the molecular pump and ion pump are activated, filament 121 stops working, baking unit 210 is shut down, and cooling unit 220 is activated. The temperature of filament 121 returns to room temperature, and the vacuum level in vacuum chamber 110 decreases from 10E. -9 Pa changes to 10E -10 Pa.

[0083] In one application scenario, the baking unit 210 is an infrared lamp, and its distribution is as follows: Figure 6 As shown in (b), the temperature of filament 121 returned to room temperature (22 degrees Celsius, 295 K) in less than 5 minutes, and the vacuum level in vacuum chamber 110 decreased from 10E. -9 Pa changes to 10E -10 Pa.

[0084] 550, cleaning in place completed.

[0085] During the completion phase, the molecular pump and ion pump are activated, and the vacuum level in vacuum chamber 110 is 10E. -10 Pa. Filament 121 starts working, baking unit 210 is turned off, cooling unit 220 is turned off, and filament temperature is room temperature, for example, 22 degrees Celsius (295K).

[0086] Figure 9 This is a schematic diagram of an application scenario for a cleaning system provided in an embodiment of this application.

[0087] Figure 9 (a) and Figure 9 (b) shows different angles of the cleaning system in application scenarios. The baking unit 210 is as follows... Figure 10 The infrared lamps shown are evenly distributed around the filament 121. The infrared lamps are connected to a power source via sockets and wiring, and receive power through these connections. The entire vacuum chamber is covered by infrared lamps, eliminating any blind spots during baking. The infrared lamp array design provided in this embodiment ensures that the surface temperature of the core components of the vacuum chamber is baked to over 200 degrees Celsius within 5 minutes, ensuring that the temperature of the core area is 30-150 degrees Celsius higher than that of the non-core areas during the baking process. With multiple infrared lamps evenly distributed around the filament 121, the filament 121 is located in the core area, and the area away from the filament 121 is the non-core area. The exhaust speed in the core area is faster than in the non-core area. Gas exhausted from the core area is adsorbed in the non-core area before being discharged from the vacuum chamber, ensuring efficient exhaust in the core area. The transfer sequence of impurities adhering to the filament surface is: core area -> non-core area -> vacuum chamber exhaust port -> vacuum pump.

[0088] This technical solution can create a temperature gradient, ensuring that the temperature in the core area is 30-150 degrees Celsius higher than that in the non-core areas, thereby ensuring highly efficient cleaning of the core area. Furthermore, by using a baking unit to bake the interior of the vacuum equipment, including the vacuum chamber and key components, the efficiency of water vapor removal within the vacuum chamber is improved, increasing the speed of vacuum baking and thus enhancing the overall vacuuming speed of the vacuum equipment.

[0089] Figure 11 This is a schematic diagram of filament temperature changes during the cleaning process provided in an embodiment of this application.

[0090] Figure 11 The temperature change diagram shown uses the following method: Figure 9The cleaning system shown can effectively clean the filament by heating it to 220 degrees Celsius in less than five minutes using infrared heating. Simultaneously, a cooling unit can reduce the filament temperature from 220 degrees Celsius to room temperature in less than seven minutes, allowing the electronic source to return to normal operation. The cleaning system provided in this application has high cleaning efficiency, with a complete self-cleaning cycle taking no more than 30 minutes, and excellent cleaning results. The filament temperature is stabilized at 220 degrees Celsius for approximately 15 minutes, effectively removing impurities adsorbed at the filament tip.

[0091] Figure 12 This is an exemplary flowchart of another cleaning method provided in the embodiments of this application.

[0092] 610, Cleaning preparation.

[0093] by Figure 4 For example, during the cleaning preparation stage, ensure that the baking unit 210 and the cooling unit 220 are properly connected. Close the door of the vacuum chamber 110, and the vacuum chamber 110 enters a sealed state. The mechanical pump starts operating, and the internal pressure of the vacuum chamber 110 increases from normal atmospheric pressure (10E). 5 Pa) decreased to 10E -1 Pa.

[0094] 620, Initiate in-situ cleaning.

[0095] During the startup phase, the mechanical pump remains running, and the molecular pump is started, causing the vacuum level inside vacuum chamber 110 to change to 10E. - 8 Pa.

[0096] The mechanical pump and the molecular pump remain running. The ion pump is started, and the vacuum level inside vacuum chamber 110 changes to 10E. -10 Pa. At this time, the filament 121 stops working, the baking unit 210 and the cooling unit 220 are turned off, and the temperature of the filament 121 is at room temperature, for example, 22 degrees Celsius (295K).

[0097] 630, heating up for cleaning.

[0098] During the heating and cleaning phase, the molecular pump and ion pump are activated, and filament 121 stops working. The baking unit 210 is activated, and its power is set to 300W. The cooling unit 220 is simultaneously located on the outer wall of the vacuum chamber 110 and inside the lamp holder 122, such as... Figure 7 As shown in (a), (b), (e) or (f), during the heating and cleaning phase, the cooling unit 220 located in the lamp holder 122 is turned off, and the cooling unit 220 located on the outer wall of the vacuum chamber 110 is turned on. The flow rate of the cooling unit 220 located on the outer wall of the vacuum chamber 110 is set to 120 ml / min.

[0099] The temperature of filament 121 rises rapidly, reaching 220 degrees Celsius after 5 minutes and maintaining that temperature for 15 minutes. Simultaneously, the vacuum level inside vacuum chamber 110 decreases from 10E. -10 Pa changes to 10E -9 Pa.

[0100] 640, temperature drop.

[0101] During the cooling phase, the molecular pump and ion pump are activated, filament 121 stops working, the baking unit 210 is shut down, and the cooling units 220, located on the outer wall of the vacuum chamber 110 and inside the lamp holder 122, are both activated, with the flow rate set to 120 ml / min. The temperature of filament 121 returns to room temperature, for example, 22 degrees Celsius (295 K), after 5 minutes. The vacuum level inside the vacuum chamber 110 decreases from 10E. -9 Pa changes to 10E - 10 Pa.

[0102] 650, complete in-situ cleaning.

[0103] During the completion phase, the molecular pump and ion pump are activated, and the vacuum level in vacuum chamber 110 is 10E. -10 Pa. Filament 121 starts working, baking unit 210 is turned off, cooling unit 220 is turned off, and filament temperature is room temperature, for example, 22 degrees Celsius (295K).

[0104] Figure 13 This is an exemplary flowchart of another cleaning method provided in the embodiments of this application.

[0105] 710, Cleaning preparation.

[0106] by Figure 4 For example, during the cleaning preparation stage, ensure that the baking unit 210 and the cooling unit 220 are properly connected. Close the door of the vacuum chamber 110, and the vacuum chamber 110 enters a sealed state. The mechanical pump starts operating, and the internal pressure of the vacuum chamber 110 increases from normal atmospheric pressure (10E). 5 Pa) decreased to 10E -1 Pa.

[0107] 720, Initiate in-situ cleaning.

[0108] During the startup phase, the mechanical pump remains running, and the molecular pump is started, causing the vacuum level inside vacuum chamber 110 to change to 10E. - 8 Pa.

[0109] The mechanical pump and the molecular pump remain running. The ion pump is started, and the vacuum level inside vacuum chamber 110 changes to 10E. -10Pa. At this time, the filament 121 stops working, the baking unit 210 and the cooling unit 220 are closed, and the temperature of the filament 121 is at normal temperature, for example, 22 degrees Celsius (295K).

[0110] 730, warming up for cleaning.

[0111] In the warming up for cleaning stage, the molecular pump is opened, the ion pump is opened, and the filament 121 stops working. The baking unit 210 is opened, and the power of the baking unit 210 is set to 250W. The cooling unit 220 is set to be located outside the outer wall of the vacuum chamber 110 and inside the lamp holder 122 at the same time, as shown in (a), (b), (e) or (f) of FIG. 2. Figure 7 In the warming up for cleaning stage, the cooling unit 220 located inside the lamp holder 122 is closed, and the cooling unit 220 located outside the outer wall of the vacuum chamber 110 is opened, and the flow rate of the cooling unit 220 located outside the outer wall of the vacuum chamber 110 is set to 120ml / min.

[0112] The temperature of the filament 121 rises rapidly, and rises to 170 degrees Celsius after 5 minutes, and is maintained at this temperature for 15 minutes. At the same time, the vacuum degree in the vacuum chamber 110 changes from 10E -10 Pa to 10E -9 Pa.

[0113] 740, cooling down.

[0114] In the cooling down stage, the molecular pump is opened, the ion pump is opened, the filament 121 stops working, the baking unit 210 is closed, and the cooling units 220 located outside the outer wall of the vacuum chamber 110 and inside the lamp holder 122 are both opened, and the flow rate is set to 120ml / min. The temperature of the filament 121 returns to normal temperature, for example, 22 degrees Celsius (295K) after 4 minutes. The vacuum degree in the vacuum chamber 110 changes from 10E -9 Pa to 10E - 10 Pa.

[0115] 750, completing in-situ cleaning.

[0116] In the completion stage, the molecular pump is opened, the ion pump is opened, and the vacuum degree in the vacuum chamber 110 is 10E -10 Pa. The filament 121 starts working, the baking unit 210 is closed, the cooling unit 220 is closed, and the temperature of the filament is at normal temperature, for example, 22 degrees Celsius (295K).

[0117] Figure 14 is an exemplary flowchart of another cleaning method provided by the embodiments of the present application.

[0118] 810, cleaning preparation.

[0119] In the preparation stage, the filament 121 stops working, the baking unit 210 is opened, the cooling unit 220 is opened, and the temperature of the filament 121 is at normal temperature, for example, 22 degrees Celsius (295K). Figure 4For example, during the cleaning preparation stage, ensure that the baking unit 210 and the cooling unit 220 are properly connected. Close the door of the vacuum chamber 110, and the vacuum chamber 110 enters a sealed state. The mechanical pump starts operating, and the internal pressure of the vacuum chamber 110 increases from normal atmospheric pressure (10E). 5 Pa) decreased to 10E -1 Pa.

[0120] 820, Initiate in-situ cleaning.

[0121] During the startup phase, the mechanical pump remains running, and the molecular pump is started, causing the vacuum level inside vacuum chamber 110 to change to 10E. - 8 Pa.

[0122] The mechanical pump and the molecular pump remain running. The ion pump is started, and the vacuum level inside vacuum chamber 110 changes to 10E. -10 Pa. At this time, the filament 121 stops working, the baking unit 210 and the cooling unit 220 are turned off, and the temperature of the filament 121 is at room temperature, for example, 22 degrees Celsius (295K).

[0123] 830, heating up for cleaning.

[0124] During the heating and cleaning phase, the molecular pump and ion pump are activated, and filament 121 stops working. The baking unit 210 is activated, and its power is set to 200W. The cooling unit 220 is simultaneously located on the outer wall of the vacuum chamber 110 and inside the lamp holder 122, such as... Figure 7 As shown in (a), (b), (e) or (f), during the heating and cleaning phase, the cooling unit 220 located in the lamp holder 122 is turned off, and the cooling unit 220 located on the outer wall of the vacuum chamber 110 is turned on. The flow rate of the cooling unit 220 located on the outer wall of the vacuum chamber 110 is set to 120 ml / min.

[0125] The temperature of filament 121 rises rapidly, reaching 150 degrees Celsius after 5 minutes and maintaining that temperature for 15 minutes. Simultaneously, the vacuum level inside vacuum chamber 110 decreases from 10E. -10 Pa changes to 10E -9 Pa.

[0126] 840, temperature drop.

[0127] During the cooling phase, the molecular pump and ion pump are activated, filament 121 stops working, the baking unit 210 is shut down, and the cooling units 220, located on the outer wall of the vacuum chamber 110 and inside the lamp holder 122, are both activated, with the flow rate set to 120 ml / min. The temperature of filament 121 returns to room temperature, for example, 22 degrees Celsius (295 K), after 3 minutes. The vacuum level inside the vacuum chamber 110 decreases from 10E. -9 Pa changes to 10E -10 Pa.

[0128] 850, cleaning in place completed.

[0129] During the completion phase, the molecular pump and ion pump are activated, and the vacuum level in vacuum chamber 110 is 10E. -10 Pa. Filament 121 starts working, baking unit 210 is turned off, cooling unit 220 is turned off, and filament temperature is room temperature, for example, 22 degrees Celsius (295K).

[0130] Figure 15 This is an exemplary flowchart of another cleaning method provided in the embodiments of this application.

[0131] 910, Cleaning preparation.

[0132] by Figure 4 For example, during the cleaning preparation stage, ensure that the baking unit 210 and the cooling unit 220 are properly connected. Close the door of the vacuum chamber 110, and the vacuum chamber 110 enters a sealed state. The mechanical pump starts operating, and the internal pressure of the vacuum chamber 110 increases from normal atmospheric pressure (10E). 5 Pa) decreased to 10E -1 Pa.

[0133] 920, Initiate in-situ cleaning.

[0134] During the startup phase, the mechanical pump remains running, and the molecular pump is started, causing the vacuum level inside vacuum chamber 110 to change to 10E. - 8 Pa.

[0135] The mechanical pump and the molecular pump remain running. The ion pump is started, and the vacuum level inside vacuum chamber 110 changes to 10E. -10 Pa. At this time, the filament 121 stops working, the baking unit 210 and the cooling unit 220 are turned off, and the temperature of the filament 121 is at room temperature, for example, 22 degrees Celsius (295K).

[0136] 930, heating up for cleaning.

[0137] During the heating and cleaning phase, the molecular pump and ion pump are activated, and filament 121 stops working. The baking unit 210 is activated, and its power is set to 300W. The cooling unit 220 is simultaneously located on the outer wall of the vacuum chamber 110 and inside the lamp holder 122, such as... Figure 7 As shown in (a), (b), (e) or (f), during the heating and cleaning phase, the cooling unit 220 located in the lamp holder 122 is turned off, and the cooling unit 220 located on the outer wall of the vacuum chamber 110 is turned on. The flow rate of the cooling unit 220 located on the outer wall of the vacuum chamber 110 is set to 120 ml / min.

[0138] The temperature of the filament 121 rises rapidly, and after 5 minutes, it rises to 220 degrees Celsius and is maintained at this temperature for 15 minutes. At the same time, the vacuum degree in the vacuum chamber 110 changes from 10E -10 Pa to 10E -9 Pa.

[0139] 940, and the temperature is lowered.

[0140] In the temperature lowering phase, the molecular pump is turned on, the ion pump is turned on, the filament 121 is stopped, the baking unit 210 is turned off, and the cooling unit 220 arranged on the outer wall of the vacuum chamber 110 and in the lamp holder 122 is turned on, with a flow rate of 240 ml / min. The temperature of the filament 121 returns to room temperature, for example, 22 degrees Celsius (295 K), after 3 minutes. The vacuum degree in the vacuum chamber 110 changes from 10E -9 Pa to 10E - 10 Pa.

[0141] 950, and the in-situ cleaning is completed.

[0142] In the completion phase, the molecular pump is turned on, the ion pump is turned on, the vacuum degree in the vacuum chamber 110 is 10E -10 Pa. The filament 121 is started, the baking unit 210 is turned off, the cooling unit 220 is turned off, and the temperature of the filament is room temperature, for example, 22 degrees Celsius (295 K).

[0143] The embodiments of the present application provide a cleaning system, which combines a hardware design and an optimized in-situ cleaning process, to ensure an ultra-high vacuum and a low pollution environment necessary for the operation of a cold field emission electron source, and to ensure an efficient and stable working state of a cold field emission electron beam detection device, i.e., high imaging resolution, high scanning rate, low maintenance, and long-term reliability.

[0144] The above merely provides specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or replacements within the technical scope disclosed in the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A cleaning system, characterized in that, An application in a cold field emission device, the cold field emission device including a vacuum chamber and a cold field emission electron source, wherein the filament of the cold field emission electron source is located within the vacuum chamber, and the cleaning system includes: A baking unit, disposed inside the vacuum chamber, is used to heat the filament to remove impurities from the surface of the filament; A cooling unit, disposed outside the vacuum chamber, is used to cool the vacuum chamber and the filament after the impurities on the filament surface have been removed.

2. The cleaning system according to claim 1, characterized in that, The baking unit includes an infrared lamp, a resistance wire, an electron beam bombardment device, or an electron gun.

3. The cleaning system according to claim 1 or 2, characterized in that, The cleaning system includes a plurality of baking units, which are evenly distributed around the filament as the center.

4. The cleaning system according to any one of claims 1 to 3, characterized in that, The number of baking units in the cleaning system is 2 to 10.

5. The cleaning system according to any one of claims 1 to 4, characterized in that, The power of the baking unit is 100W to 1000W.

6. The cleaning system according to any one of claims 1 to 5, characterized in that, The distance between the baking unit and the filament is 10mm to 100mm.

7. The cleaning system according to any one of claims 1 to 6, characterized in that, The cooling unit includes an air-cooled device or a liquid-cooled device.

8. The cleaning system according to any one of claims 1 to 7, characterized in that, The cold field emission electron source includes a lamp holder and a filament. The lamp holder includes a first part protruding into the vacuum cavity and a second part connected to the first part. The second part is disposed on the outer wall of the vacuum cavity and surrounds the outer wall of the vacuum cavity to form the vacuum cavity. The filament is fixed on the first part.

9. The cleaning system according to claim 8, characterized in that, The cooling unit is disposed on the outer wall of the vacuum chamber, or the cooling unit is disposed inside the lamp holder, or the cooling unit is disposed on both the outer wall of the vacuum chamber and inside the lamp holder.

10. The cleaning system according to claim 8 or 9, characterized in that, The cleaning system includes multiple cooling units, which are uniformly distributed on the outer wall of the vacuum chamber, or uniformly distributed inside the lamp holder, or uniformly distributed simultaneously on the outer wall of the vacuum chamber and inside the lamp holder.

11. The cleaning system according to any one of claims 1 to 10, characterized in that, The cold field emission device also includes a mechanical pump exhaust port, a molecular pump exhaust port, and an ion pump exhaust port. The mechanical pump exhaust port is used to reduce the gas pressure in the vacuum chamber to 10E. -1 Pa, the molecular pump evacuation port is used to maintain the vacuum level in the vacuum chamber at 10E. -8 Pa to 10E -1 Between Pa, the ion pump extraction port is used to maintain the vacuum level in the vacuum chamber at 10E. -10 Pa to 10E -8 Between Pa.

12. A cold field emission device, characterized in that, The device includes a vacuum chamber, a cold field emission electron source, and a cleaning system as described in any one of claims 1 to 11, wherein the filament of the cold field emission electron source is located within the vacuum chamber, and the cleaning system is used to remove impurities from the surface of the filament of the cold field emission electron source and to cool the vacuum chamber and the filament.

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