Secondary electron probe and secondary electron detector

Abstract

A secondary electron probe includes a porous carbon material layer, which is composed of a plurality of carbon material particles, and there are nano-scale or micro-scale gaps between the plurality of carbon material particles. The porous carbon material layer is an electron black body. The present invention also provides a secondary electron detector and a scanning electron microscope detector using the above secondary electron probe.

Description

Technical Field

[0001] The present invention relates to a secondary electron probe, a secondary electron detector using the secondary electron probe, and a scanning electron microscope detector. Background Art

[0002] Secondary electrons refer to electrons emitted from the surface layer of an object within a depth range of 5 - 10 nm when the surface of the object is bombarded with an electron beam or an ion beam. Secondary electrons are very sensitive to the surface morphology of the sample. Therefore, by detecting the secondary electrons emitted from the surface of the object, the surface morphology of the object can be effectively displayed. The principle of secondary electrons is applied to detection elements such as electron multiplier tubes, photomultiplier tubes, microchannel plates, Faraday cups, and Daly detectors, and also to electron imaging elements such as scanning electron microscopes. With the rapid development of electronic technology, the phenomenon of secondary electron emission and the detection elements of secondary electrons have attracted more and more extensive attention. The material of the existing secondary electron probe is generally a metal material. When secondary electrons hit the surface of the metal material, in addition to a part being absorbed, a large number of secondary electrons are reflected by the metal material or penetrate the metal material, resulting in a relatively low absorption rate of secondary electrons by the metal material, generally about forty percent. Since some of the secondary electrons escaping from the surface of the object cannot be collected by the secondary electron probe, the collection efficiency of the secondary electrons escaping from the surface of the object is reduced, and further the accuracy of the existing secondary electron detector is relatively low, and the clarity and authenticity of the surface morphology of the object detected by the scanning electron microscope are also affected.

[0003] Currently, no material with an electron absorption rate almost reaching 100% has been found. Such a material can also be called an electron black body. In the prior art, to achieve an electron absorption rate of 100%, a complex structure needs to be designed, the cost is relatively high, and the effect is not ideal. Therefore, it is of great significance to design a secondary electron probe and a secondary electron detector with a simple structure and an electron absorption rate almost reaching 100%. Summary of the Invention

[0004] In view of this, it is indeed necessary to provide a secondary electron probe with an absorption rate of secondary electrons almost reaching 100%, a secondary electron detector using the secondary electron probe, and a scanning electron microscope detector.

[0005] A secondary electron probe includes a porous carbon material layer, which is composed of a plurality of carbon material particles, and there are nano - scale or micro - scale gaps between the plurality of carbon material particles. The porous carbon material layer is an electron black body.

[0006] A secondary electron detector includes a secondary electron probe and a test unit. The secondary electron probe is connected to the test unit through a wire. The secondary electron probe includes a porous carbon material layer, which is composed of a plurality of carbon material particles. There are nano-scale or micro-scale gaps between the plurality of carbon material particles. The porous carbon material layer is an electron black body.

[0007] A scanning electron microscope detector includes a secondary electron probe and an ammeter. The ammeter includes a first terminal and a second terminal. The first terminal is electrically connected to the secondary electron probe, and the second terminal is grounded. The image display of the scanning electron microscope is electrically connected to the secondary electron probe and the ammeter, and images according to the current value in the ammeter. The secondary electron probe includes a porous carbon material layer, which is composed of a plurality of carbon material particles. There are nano-scale or micro-scale gaps between the plurality of carbon material particles. The porous carbon material layer is an electron black body.

[0008] Compared with the prior art, the secondary electron probe provided by the present invention only adopts a porous carbon material layer, with a simple structure. Moreover, the absorption rate of electrons by the porous carbon material layer can almost reach 100%, which can be regarded as an absolute black body for secondary electrons. When using this secondary electron probe to detect secondary electrons escaping from the surface of a sample, almost no secondary electrons will be missed, and the collection efficiency of secondary electrons is relatively high. Furthermore, the secondary electron detector using this secondary electron probe has a relatively high collection efficiency and detection accuracy for electrons. The surface morphology photos of the sample obtained by the scanning electron microscope detector are relatively clear and have a relatively high authenticity. Description of the Drawings

[0009] Figure 1 It is a schematic structural diagram of the secondary electron probe provided by the embodiment of the present invention.

[0010] Figure 2 It is a schematic structural diagram of the carbon nanotube structure provided by the embodiment of the present invention arranged on an insulating substrate.

[0011] Figure 3 It is a schematic structural diagram of the super-aligned carbon nanotube array provided by the embodiment of the present invention arranged on an insulating substrate.

[0012] Figure 4 It is a schematic structural diagram of the secondary electron detector provided by the embodiment of the present invention.

[0013] Figure 5 It is a schematic structural diagram and a comparison diagram of the current intensity obtained when testing a sample with the secondary electron detector of the embodiment of the present invention and the existing secondary electron detector.

[0014] Figure 6Schematic diagram of the structure of the scanning electron microscope detector provided by the embodiment of the present invention.

[0015] Figure 7 Sample pictures obtained by scanning a sample with a scanning electron microscope using the scanning electron microscope detector provided by the embodiment of the present invention and a scanning electron microscope using a Ti metal as a secondary electron probe.

[0016] Description of main component symbols

[0017] Secondary electron probe 10

[0018] Carbon nanotube structures 102, 202, 302

[0019] Insulating substrate 104

[0020] Secondary electron detector 20

[0021] Testing unit 204

[0022] Wires 206, 306

[0023] Scanning electron microscope detector 30

[0024] Ammeter 304

[0025] The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings. Specific embodiments

[0026] The following will further elaborate on the secondary electron probe, secondary electron detector, and scanning electron microscope detector provided by the present invention in conjunction with the drawings.

[0027] Please refer to Figure 1 , the first embodiment of the present invention provides a secondary electron probe 10, which includes a porous carbon material layer 102. The porous carbon material layer 102 includes a plurality of carbon material particles, and there are minute gaps between the plurality of carbon material particles. The gaps between the plurality of carbon material particles are in the nanometer or micrometer scale. The porous carbon material layer 102 is a self-supporting structure. The so-called "self-supporting" means that the porous carbon material layer 102 can maintain its specific shape without being disposed on the surface of a substrate.

[0028] The micrometer scale refers to a size less than or equal to 1000 micrometers, and the nanometer scale refers to a size less than or equal to 1000 nanometers. Further, the micrometer scale refers to a size less than or equal to 100 micrometers, and the nanometer scale refers to a size less than or equal to 100 nanometers.

[0029] The porous carbon material layer 102 is preferably a pure carbon structure, which means that the porous carbon material layer 102 is composed only of a plurality of carbon material particles, without containing other impurities, and the carbon material particles are also pure carbon material particles.

[0030] There are nano-scale or micro-scale minute gaps between the plurality of carbon material particles in the porous carbon material layer 102. After secondary electrons enter the porous carbon material layer 102, they will be refracted and reflected multiple times among the minute gaps between the plurality of carbon material particles in the porous carbon material layer 102 and cannot be emitted from the porous carbon material layer 102. The absorption rate of the porous carbon material layer 102 for electrons can almost reach 100%. That is to say, the porous carbon material layer 102 can be regarded as an absolute black body for secondary electrons. Therefore, the porous carbon material layer 102 has a particularly good effect on collecting secondary electrons. When the secondary electron probe 10 using the porous carbon material layer 102 detects the secondary electrons escaping from the surface of the sample, basically no secondary electrons will be missed, and the secondary electron collection efficiency and detection accuracy are relatively high.

[0031] Please refer to Figure 2 , the porous carbon material layer 102 can be further disposed on the surface of an insulating substrate 104. The insulating substrate 104 is preferably a flat structure. The insulating substrate 104 can be a flexible or rigid substrate. For example, glass, plastic, silicon wafer, silicon dioxide wafer, quartz wafer, polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), silicon, silicon with an oxide layer, quartz, etc. The size of the substrate is set according to actual needs. In this embodiment, the porous carbon material layer 102 is disposed on the surface of a silicon substrate 104.

[0032] The carbon material particles include one or both of linear particles and spherical particles. The maximum diameter of the cross-section of the linear particles is less than or equal to 1000 microns. The linear particles can be carbon fibers, carbon micro-wires, carbon nanotubes, etc. The maximum diameter of the spherical particles is less than or equal to 1000 microns. The spherical particles can be carbon nanospheres or carbon microspheres, etc. Preferably, the carbon material particles are carbon nanotubes, and the porous carbon material layer 102 is a carbon nanotube structure. The carbon nanotube structure is preferably a pure carbon nanotube structure, which means that the carbon nanotube structure only includes carbon nanotubes, without containing other impurities, and the carbon nanotubes are also pure carbon nanotubes. The carbon nanotube structure is a carbon nanotube array or a carbon nanotube network structure.

[0033] When the carbon nanotube structure is a carbon nanotube array, the carbon nanotube array is preferably disposed on the surface of the insulating substrate 104. And there is an intersection angle between the extending direction of the carbon nanotubes in the carbon nanotube array and the insulating substrate 104, and the intersection angle is greater than 0 degrees and less than or equal to 90 degrees. In this way, it is more beneficial for the tiny gaps between multiple carbon nanotubes in the carbon nanotube array to prevent secondary electrons from emitting from the carbon nanotube array, improve the absorption rate of the carbon nanotube array to secondary electrons, and thus improve the detection accuracy of secondary electrons.

[0034] Please refer to Figure 3 , in this embodiment, the carbon nanotube structure is a super-aligned carbon nanotube array, and the super-aligned carbon nanotube array is disposed on the surface of the insulating substrate 104. The super-aligned carbon nanotube array can be directly grown on the insulating substrate 104 or transferred from its growth substrate to the insulating substrate 104. The super-aligned carbon nanotube array includes a plurality of carbon nanotubes that are parallel to each other and perpendicular to the insulating substrate 104. Of course, there are a few randomly arranged carbon nanotubes in the super-aligned carbon nanotube array, and these carbon nanotubes will not significantly affect the overall orientation arrangement of most carbon nanotubes in the super-aligned carbon nanotube array. The super-aligned carbon nanotube array basically does not contain impurities, such as amorphous carbon or residual catalyst metal particles, etc. The carbon nanotubes in the super-aligned carbon nanotube array are in close contact with each other through van der Waals forces to form an array.

[0035] The size, thickness and surface area of the super-aligned carbon nanotube array are not limited and are defined according to actual needs. The preparation method of the super-aligned carbon nanotube array has been disclosed in many previous cases. For example, reference can be made to the Chinese patent application CN101239712A published by Feng Chen et al. on August 13, 2008. Of course, the carbon nanotube array is not limited to the super-aligned carbon nanotube array and can also be other carbon nanotube arrays.

[0036] The mesh holes formed between the carbon nanotubes in the carbon nanotube network structure are very small, being in the micron or nanometer scale. The carbon nanotube network structure can be a carbon nanotube sponge, a carbon nanotube film structure, a carbon nanotube paper, or a network structure formed by weaving or winding multiple carbon nanotube wires together, etc. Of course, the carbon nanotube network structure is not limited to the carbon nanotube sponge, the carbon nanotube film structure, the carbon nanotube paper, or the network structure formed by weaving or winding multiple carbon nanotube wires together, and can also be other carbon nanotube network structures.

[0037] The carbon nanotube sponge is a sponge-like carbon nanotube macrobody formed by multiple carbon nanotubes winding around each other, and the carbon nanotube sponge is a self-supporting porous structure.

[0038] The carbon nanotube wire includes a plurality of carbon nanotubes, and the plurality of carbon nanotubes are connected end to end by van der Waals forces to form a macroscopic linear structure. The carbon nanotube wire can be a non-twisted carbon nanotube wire or a twisted carbon nanotube wire. The non-twisted carbon nanotube wire includes a plurality of carbon nanotubes arranged along the length direction of the non-twisted carbon nanotube wire. The twisted carbon nanotube wire is formed by arranging a plurality of carbon nanotubes substantially parallel and twisting along the axial direction of the twisted carbon nanotube wire. The twisted carbon nanotube wire can be formed by relatively rotating the two ends of the non-twisted carbon nanotube wire. During the process of relatively rotating the two ends of the non-twisted carbon nanotube wire, the carbon nanotubes in the non-twisted carbon nanotube wire will be arranged in a spiral shape along the axial direction of the carbon nanotube wire and are connected end to end by van der Waals forces in the extending direction, thereby forming the twisted carbon nanotube wire.

[0039] The carbon nanotube film structure is formed by laminating a plurality of carbon nanotube films together. The adjacent carbon nanotube films are combined by van der Waals forces, and there are minute gaps between the carbon nanotubes in the carbon nanotube film structure. The carbon nanotube film can be a carbon nanotube drawn film, a carbon nanotube flocculated film, or a carbon nanotube rolled film.

[0040] The carbon nanotube drawn film includes a plurality of carbon nanotubes that are substantially parallel to each other and substantially parallel to the surface of the carbon nanotube drawn film. Specifically, the carbon nanotube drawn film includes a plurality of the carbon nanotubes connected end to end by van der Waals forces and preferably arranged in the same direction. The carbon nanotube drawn film can be obtained by directly pulling from a carbon nanotube array and is a self-supporting structure. Since a large number of carbon nanotubes in the self-supporting carbon nanotube drawn film attract each other by van der Waals forces, the carbon nanotube drawn film has a specific shape and forms a self-supporting structure. The thickness of the carbon nanotube drawn film is 0.5 nanometers to 100 micrometers, the width is related to the size of the carbon nanotube array from which the carbon nanotube drawn film is pulled, and the length is not limited. For the structure and preparation method of the carbon nanotube drawn film, please refer to the Chinese patent application No. CN101239712A, filed on February 9, 2007 and published on August 13, 2008 by Fan Shoushan et al. For the sake of saving space, it is only cited here, but all the technical disclosures of the said application should also be regarded as part of the technical disclosures of the present invention application. Most of the carbon nanotubes in the carbon nanotube drawn film are connected end to end by van der Waals forces. In one embodiment, the carbon nanotube film structure is formed by laminating and crossing multiple carbon nanotube drawn films. There is an intersection angle α between the carbon nanotubes in the adjacent carbon nanotube drawn films, and the intersection angle α is greater than 0 degree and less than or equal to 90 degrees. The carbon nanotubes in the multiple carbon nanotube drawn films are intertwined to form a net-like film structure.

[0041] The carbon nanotube flocculation film includes a plurality of carbon nanotubes that are intertwined with each other and evenly distributed. The carbon nanotubes attract and wind around each other through van der Waals forces to form a network structure, so as to form a self-supporting carbon nanotube flocculation film. The carbon nanotube flocculation film is isotropic. The carbon nanotube flocculation film can be obtained by flocculating a carbon nanotube array. For the structure and preparation method of the carbon nanotube flocculation film, please refer to the Chinese patent application No. CN101284662A filed by Fan Shoushan et al. on April 13, 2007 and published on October 15, 2008. For the sake of brevity, it is only cited here, but all the technical disclosures in the said application should also be regarded as part of the technical disclosures of the present invention application.

[0042] The carbon nanotube rolling film includes a plurality of carbon nanotubes arranged disorderly, preferentially oriented in one direction or preferentially oriented in multiple directions, and adjacent carbon nanotubes are combined through van der Waals forces. The carbon nanotube rolling film can be obtained by extruding the carbon nanotube array with a planar indenter along the direction perpendicular to the substrate on which the carbon nanotube array grows. At this time, the carbon nanotubes in the carbon nanotube rolling film are arranged disorderly, and the carbon nanotube rolling film is isotropic; the carbon nanotube rolling film can also be obtained by rolling the carbon nanotube array with a roller-shaped indenter along a certain fixed direction. At this time, the carbon nanotubes in the carbon nanotube rolling film are preferentially oriented in the fixed direction; the carbon nanotube rolling film can also be obtained by rolling the carbon nanotube array with a roller-shaped indenter along different directions. At this time, the carbon nanotubes in the carbon nanotube rolling film are preferentially oriented in different directions. For the structure and preparation method of the carbon nanotube rolling film, please refer to the Chinese patent application No. CN101314464A filed by Fan Shoushan et al. on June 1, 2007 and published on December 3, 2008. For the sake of brevity, it is only cited here, but all the technical disclosures in the said application should also be regarded as part of the technical disclosures of the present invention application.

[0043] The carbon nanotube paper includes a plurality of carbon nanotubes that are basically arranged in the same direction, and the plurality of carbon nanotubes are connected end to end through van der Waals forces in their extending direction, and the plurality of carbon nanotubes are basically parallel to the surface of the carbon nanotube paper. For the structure and preparation method of the carbon nanotube paper, please refer to the Chinese patent No. CN103172044B filed by Fan Shoushan et al. on December 21, 2011 and announced on July 1, 2015. For the sake of brevity, it is only cited here, but all the technical disclosures in the said application should also be regarded as part of the technical disclosures of the present invention application.

[0044] Since the carbon nanotube structure is relatively pure and the specific surface area of the carbon nanotubes in the carbon nanotube structure is relatively large, and the carbon nanotube structure itself has a large viscosity. Therefore, when the carbon nanotube structure is disposed on the insulating substrate 104, the carbon nanotube structure can be fixed on the surface of the insulating substrate 104 by its own adhesion force. It can be understood that in order to better fix the carbon nanotube structure on the surface of the insulating substrate 104, the carbon nanotube structure can also be fixed on the surface of the insulating substrate 104 by an adhesive. In this embodiment, the carbon nanotube structure is fixed on the surface of the insulating substrate 104 by its own adhesion force.

[0045] Since the higher the energy of the electron beam, the deeper its penetration depth in the porous carbon material layer 102. Conversely, the penetration depth is shallower. For an electron beam with an energy less than or equal to 20 keV, preferably, the thickness range of the porous carbon material layer 102 is 200 microns to 600 microns. Within this thickness range, the electron beam is neither easily penetrated through the porous carbon material layer 102 nor easily reflected from the porous carbon material layer 102, and the absorption rate of electrons by the porous carbon material layer 102 is relatively high within this range. More preferably, the thickness of the porous carbon material layer 102 is 300 - 500 microns. More preferably, the thickness range of the porous carbon material layer 102 is 250 - 400 microns.

[0046] When the porous carbon material layer 102 is a super-aligned carbon nanotube array, the height of the super-aligned carbon nanotube array is preferably 350 - 600 microns. Within this height range, the electrons are neither easily penetrated through the super-aligned carbon nanotube array nor easily reflected from the super-aligned carbon nanotube array, and the absorption rate of electrons by the super-aligned carbon nanotube array is relatively high within this height range. More preferably, the height of the super-aligned carbon nanotube array is 400 - 550 microns. In this embodiment, the porous carbon material layer 104 is a super-aligned carbon nanotube array, and the thickness of the super-aligned carbon nanotube array is 550 microns.

[0047] When the secondary electron probe 10 is in use, when the electron beam hits the surface of the sample, the sample emits secondary electrons, and the secondary electrons are collected by the porous carbon material layer 102, and then the secondary electrons are detected.

[0048] The secondary electron probe 10 of the present invention only adopts a porous carbon material layer, with a simple structure; moreover, the microporous structure 102 can be regarded as an absolute black body for secondary electrons. Therefore, the porous carbon material layer has a particularly good effect on collecting secondary electrons. When using this secondary electron probe to detect the secondary electrons escaping from the surface of a sample, basically no secondary electrons will be missed. The absorption rate of this secondary electron probe 10 for secondary electrons can reach over 99.99%, and the collection effect and detection accuracy are relatively high. The porous carbon material layer can be a carbon nanotube structure. Since the carbon nanotube structure has good electrical conductivity, flexibility, and strength, it can also be applied in extremely harsh environments such as high temperature and low temperature. Therefore, the application range of this secondary electron probe 10 is relatively wide. Moreover, the mass of the carbon nanotube structure is relatively light, which is beneficial for actual operation, and this secondary electron probe 10 can be applied to micro-devices with strict requirements for mass and volume.

[0049] Please refer to Figure 4 , the second embodiment of the present invention provides a secondary electron detector 20, which includes a secondary electron probe 202 and a test unit 204. The test unit 204 includes a first terminal and a second terminal. Among them, the first terminal is electrically connected to the secondary electron probe 202 through a wire 206, and the second terminal is grounded.

[0050] The secondary electron probe 202 adopts the secondary electron probe 10 in the first embodiment, and this secondary electron probe 202 includes all the technical features of the secondary electron probe 10 in the first embodiment, which will not be elaborated here.

[0051] The test unit 204 is used to test the secondary electrons collected by the secondary electron probe 202 and perform numerical conversion. The test unit 204 can be an ammeter, a voltmeter, a temperature display, etc. In this embodiment, the test unit 204 is an ammeter. When the secondary electrons collected by the secondary electron probe 202 are transmitted to the ammeter through a wire, the current value generated by the secondary electrons can be read through the ammeter, and then the amount of secondary electrons escaping from the surface of the sample can be obtained.

[0052] The signal measured by the test unit 204 can be further output through an output unit (not shown in the figure). The output unit can be an image display, an alarm, etc. In this embodiment, the output unit is an LCD display, and this LCD display forms an image output according to the current signal measured by the test unit 204.

[0053] When the secondary electron detector 20 is in use, when the electron beam hits the surface of the sample, secondary electrons are emitted from the sample surface. These secondary electrons are collected by the secondary electron probe 202, and the secondary electrons collected by the secondary electron probe 202 are transmitted to the test unit 204 through a wire. The test unit 204 tests these secondary electrons. For example, the test unit 204 can test the current, voltage, temperature, etc. generated by the secondary electrons collected by the secondary electron probe 202. The amount of secondary electrons emitted from the sample surface can be obtained from the values measured by the test unit 204. The signals measured by the test unit 204 can be further output through an output unit, such as forming an image, etc.

[0054] Please refer to Figure 5 , using the secondary electron detector 20 of the present invention that uses a super-aligned carbon nanotube array as the secondary electron probe and the existing secondary electron detector with Ti metal as the secondary electron probe, Al, Si / SiO2, Ti, Cu, Ag, and Au are respectively tested. The only difference between the two secondary electron detectors is the material of the secondary electron probe, and other components are the same. As can be seen from Figure 5 the inset in Fig. a, under the same conditions, when testing the Au sample, the collection efficiency of the secondary electrons by the secondary electron detector 20 of the present invention is increased by 46.21%; when testing the Si / SiO2 sample (where the thickness of SiO2 is 300 nm), the collection efficiency is increased by 67.5%. Figure 5 The slope in Fig. b represents the ratio of the current intensities collected when the secondary electron detector 20 of the present invention and the existing secondary electron detector with Ti metal as the secondary electron probe detect the same sample under the same sample. As can be seen from Figure 5 Fig. b, when testing the Al, Si / SiO2, Ti, Cu, Ag, and Au samples, the collection efficiency of the secondary electron detector 20 of the present invention is increased by about 50% compared with the existing secondary electron detector with Ti metal as the secondary electron probe. It shows that compared with the existing secondary electron detector with Ti metal as the secondary electron probe, more secondary electrons emitted from the sample surface are collected by the secondary electron detector 20 of the present invention, the collection effect of the secondary electrons is better, and the accuracy of detecting the secondary electrons by the secondary electron detector 20 is higher.

[0055] The secondary electron detector 20 provided by the present invention uses a porous carbon material layer as the secondary electron probe. The porous carbon material layer can be regarded as an absolute black body for secondary electrons. Therefore, the porous carbon material layer has an excellent effect on collecting secondary electrons. When detecting secondary electrons escaping from the surface of a sample using the secondary electron detector 20, basically no secondary electrons will be missed, and the secondary electron collection efficiency and detection accuracy are relatively high. The secondary electron probe in the secondary electron detector 20 can achieve an absorption rate of almost 100% for secondary electrons only by using the porous carbon material layer. Therefore, the structure of the secondary electron detector 20 is simple. When the porous carbon material layer is a carbon nanotube structure, due to the good electrical conductivity, flexibility and strength of the carbon nanotube structure, it can also be applied in extremely harsh environments such as high temperature and low temperature. Therefore, the application range of the secondary electron detector 20 is relatively wide; moreover, the mass of the carbon nanotube structure is relatively light, which is beneficial to actual operation, and the secondary electron detector 20 can be applied to micro-devices with strict requirements on mass and volume.

[0056] Please refer to Figure 6 , the third embodiment of the present invention provides a scanning electron microscope detector 30, which includes a secondary electron probe 302 and an ammeter 304. The ammeter 304 includes a first terminal and a second terminal. Among them, the first terminal is electrically connected to the secondary electron probe 302 through a wire, and the second terminal is grounded. The image display of the scanning electron microscope is electrically connected to the secondary electron probe 302 and the ammeter 304, and forms an image according to the current value in the ammeter 304.

[0057] The secondary electron probe 302 is the secondary electron probe 10 in the first embodiment, which includes all the technical features of the secondary electron probe 10 in the first embodiment and will not be elaborated here. That is to say, the secondary electron probe 302 includes the porous carbon material layer 102 in the first embodiment.

[0058] The secondary electron probe 302 can be arranged at any position in the chamber of the scanning electron microscope as long as it is ensured to be spaced apart from the sample. Preferably, the secondary electron probe 302 is arranged on the side wall of the chamber of the scanning electron microscope. Since the sample is generally placed at the bottom of the chamber of the scanning electron microscope, when the secondary electron probe 302 is arranged on the side wall of the chamber of the scanning electron microscope, the secondary electron probe 302 is located obliquely above the sample, which is more conducive to collecting secondary electrons escaping from the surface of the sample. Compared with the existing scanning electron microscope detector, the distance between the secondary electron probe 302 of the present invention and the sample is relatively close, thereby making the collection rate of secondary electrons higher. It can be understood that the secondary electron probe 302 can also be not fixed on the side wall of the chamber of the scanning microscope, but arranged in the chamber of the scanning microscope through a fixing bracket.

[0059] When the porous carbon material layer 102 in the secondary electron probe 302 is a carbon nanotube array, there is preferably an intersection angle between the extending direction of the carbon nanotubes in the carbon nanotube array and the side wall of the chamber, and the intersection angle is greater than 0 degrees and less than or equal to 90 degrees. In this way, it is more beneficial for the small gaps between multiple carbon nanotubes in the carbon nanotube array to prevent secondary electrons from escaping from the carbon nanotube array, and improve the collection rate of secondary electrons by the carbon nanotube array. In this embodiment, the porous carbon material layer 102 is a super-aligned carbon nanotube array, and the extending direction of the carbon nanotubes in the super-aligned carbon nanotube array is perpendicular to the side wall of the chamber of the scanning microscope.

[0060] When the scanning electron microscope detector 30 is in use, when the high-energy electron beam emitted by the electron emission end of the scanning electron microscope hits the sample, secondary electrons escape from the sample surface. The secondary electrons are collected by the secondary electron probe 302, and the current generated by the secondary electrons collected by the secondary electron probe 302 is read through the ammeter 304. The image display device of the scanning electron microscope forms an image according to the current value, and then obtains a photo of the surface topography of the sample.

[0061] Figure 7 In Figure a and Figure b are images collected when testing the same sample to be measured by the scanning electron microscope of the present invention using a super-aligned carbon nanotube array as the secondary electron probe and the scanning electron microscope using Ti metal as the secondary electron probe. The sample to be measured is a gold electrode placed on a Si / SiO2 substrate. Figure 7 In the scanning electron microscopes used in Figure a and Figure b, only the secondary electron probes are different, and other components are the same, and the scanned samples are also exactly the same. Comparing Figure 7 Figure a and Figure b, it can be seen that compared with the images collected by the existing scanning electron microscope using Ti metal as the secondary electron probe, the image collected by the scanning electron microscope using the scanning electron microscope detector 30 of the present invention is darker in color, indicating that the current collected by the scanning electron microscope detector 30 of the present invention is stronger and more secondary electrons are collected.

[0062] In the scanning electron microscope detector 30 provided by the present invention, the secondary electron probe adopts a porous carbon material layer. There are minute gaps between multiple carbon material particles in the porous carbon material layer. After secondary electrons enter the porous carbon material layer, they will undergo multiple refractions and reflections among the minute gaps between multiple carbon material particles in the porous carbon material layer and cannot exit from the porous carbon material layer. The porous carbon material layer can be regarded as an absolute black body for secondary electrons. Therefore, the scanning electron microscope detector 30 has a particularly good collection effect on secondary electrons. When using this scanning electron microscope detector to detect secondary electrons escaping from the surface of a sample, basically no secondary electrons will be missed. Furthermore, the surface morphology photo of the sample obtained by the scanning electron microscope using this scanning electron microscope detector 30 is relatively clear and has a relatively high degree of authenticity. And because the absorption rate of the porous carbon material layer for secondary electrons is above 99.99%, almost reaching 100%, the electrical signal obtained by the ammeter is relatively strong. Therefore, there is no need for the electro-optical-electrical conversion as in existing scanning electron microscopes. The secondary electron probe in the scanning electron microscope detector 30 collects secondary electrons and directly measures the current value through an ammeter. The image display of the scanning electron microscope forms an image based on this current signal, and then obtains the surface morphology photo of the sample. The testing process is simple and the testing time is short. Moreover, the scanning electron microscope detector of the present invention can simplify the structure of the scanning electron microscope and reduce the cost.

[0063] In addition, those skilled in the art can also make other changes within the spirit of the present invention. Of course, these changes made in accordance with the spirit of the present invention should all be included within the scope claimed by the present invention.

Claims

1. A scanning electron microscope detector includes a secondary electron probe and an ammeter. The ammeter includes a first terminal and a second terminal. The first terminal is electrically connected to the secondary electron probe, and the second terminal is grounded. The image display of the scanning electron microscope is electrically connected to the secondary electron probe and the ammeter, and forms an image according to the current value in the ammeter. The secondary electron probe includes a porous carbon material layer, which is composed of a plurality of carbon material particles, and there are nano-scale or micro-scale gaps between the plurality of carbon material particles. The porous carbon material layer is an electron black body.

2. The scanning electron microscope detector according to claim 1, characterized in that, The carbon material particles are one or more of carbon nanotubes, carbon fibers, carbon nanowires, carbon microspheres or carbon nanospheres.

3. The scanning electron microscope detector as described in claim 2, characterized in that, The carbon nanotube structure is a carbon nanotube array or a carbon nanotube network structure.

4. The scanning electron microscope detector according to claim 3, wherein, The carbon nanotube network structure is a carbon nanotube sponge, a carbon nanotube film structure, a carbon nanotube paper, or a network structure formed by weaving or winding a plurality of carbon nanotubes together.

5. The scanning electron microscope detector according to claim 1, characterized in that, The thickness range of the porous carbon material layer is 200 microns to 600 microns.

6. The scanning electron microscope detector according to claim 1, wherein The porous carbon material layer is a super-aligned carbon nanotube array, and the height of the super-aligned carbon nanotube array is 400 - 550 microns.

7. The scanning electron microscope detector according to claim 1, wherein The porous carbon material layer is disposed on an insulating substrate.

8. The scanning electron microscope detector according to claim 1, characterized in that, The secondary electron probe is disposed on the side wall of the chamber of the scanning electron microscope.

Images