CN216054568U - Scanning electron microscope electronic detector with high collection efficiency - Google Patents
Scanning electron microscope electronic detector with high collection efficiency Download PDFInfo
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- CN216054568U CN216054568U CN202121659108.3U CN202121659108U CN216054568U CN 216054568 U CN216054568 U CN 216054568U CN 202121659108 U CN202121659108 U CN 202121659108U CN 216054568 U CN216054568 U CN 216054568U
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Abstract
The utility model provides a scanning electron microscope electronic detector with high collection efficiency, which improves the collection efficiency of secondary electrons or backscattered electrons and can further improve the signal-to-noise ratio and the resolution of images. It includes: a grid; a Faraday cup; a scintillator; a light guide post; a photomultiplier tube; a high voltage power supply; a current amplification circuit board; a stainless steel housing; the electron signal input end of the Faraday cup is provided with an outward-protruding screen, the electron signal output end of the Faraday cup is arranged towards the scintillator, the photon signal output end of the scintillator is arranged towards the input end of the light guide pillar, the output end of the light guide pillar is connected to the signal input end of the photomultiplier, the signal output end of the photomultiplier is connected with the signal input end of the current amplification circuit board, and the photomultiplier is connected with a high-voltage power supply; the stainless steel shell is internally wrapped with a high-voltage power supply, a photomultiplier, a light guide post and a scintillator, and the front input end of the stainless steel shell is fixedly provided with a Faraday cup.
Description
Technical Field
The utility model relates to the technical field of material transportation, in particular to a scanning electron microscope electronic detector with high collection efficiency.
Background
The Scanning Electron Microscope (SEM) is a microscopic morphology observation means between a transmission electron microscope and an optical microscope, and can directly utilize the material performance of the surface material of a sample to carry out microscopic imaging. After the high-energy electron beam enters the sample, various information such as secondary electrons, backscattered electrons, X-rays and the like can be excited on the surface of the sample. The information is detected by corresponding detectors, processed and amplified, and then transmitted to a display screen to modulate the brightness of the display screen. The scanning electron microscope adopts the progressive scanning and point-by-point scanning method to sequentially and proportionally convert different information characteristics on the surface of a sample into video signals, so that an amplified microscopic morphology image corresponding to the surface of the sample can be observed.
The secondary electrons refer to extra-nuclear electrons bombarded by a high-energy incident electron beam of the sample, mainly come from a subsurface with the depth of 1-10 nm from the surface of the sample, the energy of the secondary electrons is 0-50 eV, and the average energy is about 30eV, so that the secondary electrons can well display the micro-morphology of the surface of the sample. The emissivity of the secondary electrons changes less significantly with atomic number, depending mainly on the morphology of the sample. And back-scattered electrons refer to the interaction of incident electrons with the sample, in which a part of the electrons escape back to the surface and have an energy greater than 50eV and less than the incident energy. At a certain acceleration voltage, the yield of backscattered electrons increases with the increase of the atomic number of the sample. Therefore, the backscattered electrons are used as imaging signals to analyze the morphological characteristics of the sample, and can also be used for displaying the composition characteristics of chemical components to roughly qualitatively analyze the component distribution of the sample. In the current mainstream scanning electron microscope, the azimuth is limited, the receiving efficiency of electronic signals is limited, and the problems of signal escape and the like exist, so that the imaging efficiency and the resolution of the electronic detector are reduced. In addition, the efficiency of receiving backscattered electrons with conventional E-T secondary electron detectors is only 2% to 4% and the signal-to-noise ratio is poor. Therefore, separate secondary and backscattered electron detectors are often used for achieving the morphological and compositional imaging, respectively. Therefore, it is urgently needed to improve the structure of the detector, improve the collection efficiency of secondary electrons or backscattered electrons, further improve the signal-to-noise ratio and resolution of an image, and reduce the cost of the detector by using the modified electron detector to simultaneously detect the secondary electrons and the backscattered electrons.
Disclosure of Invention
In view of the above problems, the present invention provides a scanning electron microscope electron detector with high collection efficiency, which improves the collection efficiency of secondary electrons or backscattered electrons, can further improve the signal-to-noise ratio and resolution of images, and has the function of detecting secondary electrons and backscattered electrons, thereby reducing the cost of the detector, and realizes in-situ observation of the sample morphology and chemical components by switching the grid voltage.
The utility model provides a scanning electron microscope electron detector of high collection efficiency which characterized in that, it includes:
a grid mesh that selectively attracts and repels low-energy secondary electrons and high-energy backscattered electrons by applying positive and negative voltages;
a Faraday cup for collecting and converging the electronic signals collected by the grid;
a scintillator that converts an electronic signal incident on a scintillator phosphor layer into a photon signal;
the light guide post transmits photon signals generated by the fluorescent layer of the scintillator to the photomultiplier tube, so that the loss of the photon signals is avoided;
the photomultiplier is used for multiplying and amplifying the transmitted photon signals and converting the multiplied signals into electric signals;
the high-voltage power supply is used for supplying voltage to the photomultiplier;
the current amplification circuit board receives the multiplied and amplified electric signals, processes the signals and amplifies the current, and transmits the processed signals to an external display screen for display;
the stainless steel shell forms an electromagnetic shielding shell and prevents electronic signals from being interfered by an external electromagnetic field;
an electronic signal input end of the Faraday cup is provided with an outward-protruding screen, an electronic signal output end of the Faraday cup faces the scintillator, a photon signal output end of the scintillator faces an input end of a light guide pillar, an output end of the light guide pillar is connected to a signal input end of the photomultiplier, a signal output end of the photomultiplier is connected to a signal input end of the current amplification circuit board, and the photomultiplier is connected with a high-voltage power supply;
the high-voltage power supply, the photomultiplier, the light guide post and the scintillator are wrapped in the stainless steel shell, and the Faraday cup is fixedly mounted at the front input end of the stainless steel shell.
It is further characterized in that:
the gem pad is arranged between the scintillator and the input end of the light guide column and is used for preventing the light guide column from directly contacting the scintillator and damaging the scintillator;
a graphite ring is arranged on the ring wall of the output channel of the Faraday cup and is used for fully collecting electronic signals to a scintillator fluorescent layer at the rear part;
the scintillator is specifically a P47 scintillator, a YAG scintillator or a YAP scintillator;
the axial front end of the photomultiplier is a signal input end, the axial rear end of the photomultiplier is provided with the high-voltage power supply, and the side of the axial area of the photomultiplier is provided with a current amplification circuit board, so that the structural arrangement of the whole product is reasonable and convenient;
the stainless steel shell comprises a rear end shell, a middle connecting piece and a front end shell, wherein a high-voltage power supply, a current amplification circuit board and a photomultiplier are wrapped in the rear end shell, the middle connecting piece is used for connecting the rear end shell and the front end shell, an axial inner cavity formed by the front end shell and the middle connecting piece is wrapped with a light guide pillar, a scintillator and a gem gasket, the axial front part of the front end shell is provided with the Faraday cup, and an electronic signal input end of the Faraday cup is exposed out of the front end shell and fixedly provided with a screen;
preferably, the mesh surface of the screen is convexly arranged.
After the technical scheme is adopted, the screen is externally connected with a power supply, positive voltage is applied to the screen, the attracted secondary electrons are collected and converged through a Faraday cup, and are accelerated through high voltage in front of the scintillator and then enter a fluorescent layer of the scintillator, the fluorescent layer of the scintillator can emit light to generate photon signals after being excited by the secondary electrons, the photon signals are transmitted to a photomultiplier along a glass light guide column, the photon signals are converted into electric signals and multiplied and amplified, then the electric signals are subjected to signal processing through a current amplification circuit board, and finally the signals are output to a display screen after being subjected to power amplification, and the display screen displays video images; when negative voltage is applied to the grid mesh, the negative voltage can repel low-energy secondary electrons and only allows high-energy back-scattered electrons to pass through, the back-scattered electrons are collected and converged by the Faraday cup and enter a fluorescent layer on the scintillator, and a photoelectric signal generated by the excitation of the fluorescent layer is converted, multiplied and amplified to finally become a video image in the display screen; the novel scanning electron microscope electronic detector with high collection efficiency can realize the simultaneous detection of low-energy secondary electrons and high-energy back-scattered electrons by switching different grid voltages, and the total number of electronic signals incident on a fluorescent layer of a scintillator is increased by utilizing the Faraday cup, so that the collection efficiency of the electronic signals is improved, the signal-to-noise ratio of images is improved, and the images with high imaging precision are finally realized; the device improves the collection efficiency of secondary electrons or backscattered electrons, can further improve the signal-to-noise ratio and the resolution of images, and has the function of detecting the secondary electrons and the backscattered electrons, so that the cost of the detector is reduced, and the in-situ observation of the appearance and the chemical components of a sample is realized by switching the grid voltage.
Drawings
FIG. 1 is a schematic cross-sectional view of the present invention;
FIG. 2 is an image of a detection performed by the prior art;
FIG. 3 is an image of a high collection efficiency SEM electron detector;
the names corresponding to the sequence numbers in the figure are as follows:
the device comprises a grid mesh 1, a Faraday cup 2, a graphite ring 3, a scintillator 4, a gem pad 5, a light guide column 6, a light guide column guide sleeve component 61, a first cover plate 62, a photomultiplier 7, a second sleeve 71, a first flange cover 72, a rear convex connecting head 73, a high-voltage power supply 8, a battery installation shell 81, a second flange cover 82, an inner groove 83, a current amplification circuit board 9, a stainless steel shell 10, a rear end shell 11, a connecting ring surface 111, a middle connecting piece 12, a front end shell 13, an encapsulation cover plate 14 and a circuit board installation cover plate 15.
Detailed Description
A scanning electron microscope electronic detector with high collection efficiency is shown in figure 1 and comprises a grid 1, a Faraday cup 2, a scintillator 4, a light guide column 6, a photomultiplier tube 7, a high-voltage power supply 8, a current amplification circuit board 9 and a stainless steel shell 10;
the grid mesh 1 selectively attracts and repels low-energy secondary electrons and high-energy back-scattered electrons by applying positive and negative voltages; the Faraday cup 2 collects and converges the electronic signals collected by the grid 1; the scintillator 4 converts an electronic signal incident on the scintillator fluorescent layer into a photon signal; the light guide post 6 transmits photon signals generated by the fluorescent layer of the scintillator to the photomultiplier tube 7, so that the loss of the photon signals is avoided; the photomultiplier 7 multiplies and amplifies the transmitted photon signals and converts the multiplied signals into electric signals; the high-voltage power supply 8 supplies voltage to the photomultiplier tube 7; the current amplification circuit board 9 is used for receiving the multiplied and amplified electric signal, processing the signal and amplifying the current, and transmitting the processed signal to an external display screen for display;
a stainless steel case 10 forming an electromagnetic shield case for preventing an electronic signal from being interfered by an external electromagnetic field;
an electronic signal input end of a Faraday cup 2 is provided with a convex screen mesh 1, an electronic signal output end of the Faraday cup 2 is arranged towards a scintillator 4, a photon signal output end of the scintillator 4 is arranged towards an input end of a light guide pillar 6, an output end of the light guide pillar 6 is connected to a signal input end of a photomultiplier tube 7, a signal output end of the photomultiplier tube 7 is connected with a signal input end of a current amplification circuit board 9, and the photomultiplier tube 7 is connected with a high-voltage power supply 8;
the stainless steel shell 10 is internally wrapped with a high-voltage power supply 8, a photomultiplier tube 7, a light guide column 6 and a scintillator 4, and the front input end of the stainless steel shell 10 is fixedly provided with the Faraday cup 2.
In specific implementation, as shown in fig. 1:
the light guide column is characterized by further comprising a gem pad 5, wherein the gem pad 5 is arranged between the scintillator 4 and the input end of the light guide column 6 and is used for preventing the light guide column 6 from directly contacting the scintillator 4 and damaging the scintillator 4;
a graphite ring 3 is arranged on the ring wall of an output channel of the Faraday cup 2, and the graphite ring 3 is used for fully collecting electronic signals to a fluorescent layer of a scintillator 4 at the rear part;
the scintillator 4 is specifically a P47 scintillator, a YAG scintillator, or a YAP scintillator;
the axial front end of the photomultiplier 7 is a signal input end, the axial rear end of the photomultiplier 7 is provided with a high-voltage power supply 8, and the side of the axial region of the photomultiplier 7 is provided with a current amplification circuit board 9, so that the structural arrangement of the whole product is reasonable and convenient.
In the specific embodiment, see fig. 1: the stainless steel shell 10 comprises a rear end shell 11, a middle connecting piece 12 and a front end shell 13, wherein a high-voltage power supply 8 and a photomultiplier 7 are wrapped in the rear end shell 11, a circuit board mounting cover plate 15 is arranged beside the rear end shell, a current amplification circuit board 9 is placed in a cavity formed by combining the circuit board mounting cover plate 15 and the rear end shell 11, a signal output end of the photomultiplier 7 is connected to an input end of the current amplification circuit board 9 through wire connection or metal contact, the middle connecting piece 12 is used for connecting the rear end shell 11 and the front end shell 13, a light guide column 6, a scintillator 4 and a gem gasket 5 are wrapped in an axial inner cavity formed by the front end shell 13 and the middle connecting piece 12, a Faraday cup 2 is mounted at the axial front part of the front end shell 13, and an electronic signal input end of the Faraday cup 2 is exposed out of the front end shell 13 and fixedly provided with a screen mesh 1;
the screen surface of the screen mesh 1 is arranged in a forward convex mode to form a hemispherical structure; a light guide column guide sleeve component 61 is arranged on the periphery of the outer ring of the light guide column 6, a first cover plate 62 is covered on the front part of the light guide column guide sleeve component 61, the scintillator 4 and the gem pad 5 are arranged at the front end position of the light guide column 6 through the first cover plate 62, the rear end of the light guide column guide sleeve component 61 is connected with the middle connecting piece 12 through the middle connecting sleeve 63, a second sleeve 71 is arranged on the periphery of the outer ring of the photomultiplier 7, a first flange cover 72 is arranged at the rear end of the second sleeve 71, the high-voltage power supply 8 is arranged in the battery mounting shell 81, a second flange cover 82 is arranged at the front end of the battery mounting shell 81, a rear male connector 73 is arranged at the rear end of the axis of the photomultiplier 7, the rear male connector 73 is positioned and inserted in an inner groove 83 of the high-voltage power supply 8, and the first flange cover 72, the second flange cover 82 is fixed to the corresponding connecting ring surface 111 of the rear housing 11 by bolts, and the end of the rear housing 11 is covered with the cover plate 14.
In a specific embodiment, the faraday cup 2 is specifically a brass faraday cup, the screen 1 is specifically a red copper screen, the scintillator 4 is specifically a P47 scintillator, the light guide column 6 is specifically a K9 glass light guide column, and the sapphire shim 5 is specifically a sapphire shim.
When the method is implemented specifically, a power supply is externally connected with the screen, the +300V voltage is applied to the screen, the attracted secondary electrons are collected and converged through a Faraday cup, and are accelerated by high voltage in front of a scintillator and enter a fluorescent layer of the scintillator, the fluorescent layer of the scintillator can emit light to generate photon signals after being excited by the secondary electrons, the photon signals are transmitted to a photomultiplier along a glass light guide column, the optical signals are converted into electric signals and multiplied and amplified, then the electric signals are subjected to signal processing through a current amplification circuit board, and finally the signals are output to a display screen after being subjected to power amplification, and the display screen displays video images; when-150V voltage is applied to the grid mesh, the negative voltage can repel low-energy secondary electrons and only allows high-energy back-scattered electrons to pass through, the back-scattered electrons are collected and converged by the Faraday cup, the back-scattered electrons are incident to a fluorescent layer on the scintillator, and photoelectric signals generated by the excitation of the fluorescent layer are converted, multiplied and amplified to finally become video images in the display screen.
The device can realize the simultaneous detection of low-energy secondary electrons and high-energy back-scattered electrons by switching different grid voltages, and increases the total number of electronic signals incident on a fluorescent layer of the scintillator by using the Faraday cup, thereby improving the collection efficiency of the electronic signals, improving the signal-to-noise ratio of images and finally realizing the images with high imaging precision; the device improves the collection efficiency of secondary electrons or backscattered electrons, can further improve the signal-to-noise ratio and the resolution of images, and has the function of detecting the secondary electrons and the backscattered electrons, so that the cost of the detector is reduced, and the in-situ observation of the appearance and the chemical components of a sample is realized by switching the grid voltage.
Comparison of the prior art test and the test of the specific examples is as follows
The prior art detects: a conventional secondary electron detector is used in a tungsten filament thermal emission scanning electron microscope, a standard solder ball sample is placed in a sample cabin, then the sample cabin is vacuumized, after the vacuum is finished, an electron gun is turned on, the accelerating voltage is set to be 20kV, the working distance is 15mm, and the solder ball sample is observed under the 10000x magnification after the focusing and the astigmatism elimination are finished. After the image is collected (see fig. 2), the image is blurred, the edge is rough, and the contrast is poor. Therefore, in this case, the detection efficiency of the conventional electron detector is low.
The specific embodiment comprises the following steps: a scanning electron microscope electron detector with high collection efficiency is used in a tungsten filament thermal emission scanning electron microscope, a standard solder ball sample is placed in a sample cabin, then the sample cabin is vacuumized, after the vacuum is finished, an electron gun is turned on, the accelerating voltage is set to be 30kV, the working distance is 5mm, and the solder ball sample is observed under the magnification of 12000x after the focusing and the astigmatism elimination are finished. After the image is collected (see figure 3), the clear image, sharp edge, obvious contrast and greatly improved imaging effect can be found. Therefore, in this case, the detection efficiency of the scanning electron microscope electron detector is greatly improved.
It will be evident to those skilled in the art that the utility model is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the utility model being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.
Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.
Claims (7)
1. The utility model provides a scanning electron microscope electron detector of high collection efficiency which characterized in that, it includes:
it includes:
a grid;
a Faraday cup;
a scintillator;
a light guide post;
a photomultiplier tube;
a high voltage power supply;
a current amplification circuit board;
a stainless steel housing;
an electronic signal input end of the Faraday cup is provided with an outward-protruding screen, an electronic signal output end of the Faraday cup faces the scintillator, a photon signal output end of the scintillator faces an input end of a light guide pillar, an output end of the light guide pillar is connected to a signal input end of the photomultiplier, a signal output end of the photomultiplier is connected to a signal input end of the current amplification circuit board, and the photomultiplier is connected with a high-voltage power supply;
the high-voltage power supply, the photomultiplier, the light guide post and the scintillator are wrapped in the stainless steel shell, and the Faraday cup is fixedly mounted at the front input end of the stainless steel shell.
2. A scanning electron microscope electron detector with high collection efficiency as claimed in claim 1, wherein: it also includes a gemstone pad disposed between the scintillator and the input end of the light guide column.
3. A scanning electron microscope electron detector with high collection efficiency as claimed in claim 2, wherein: and a graphite ring is arranged on the ring wall of the output channel of the Faraday cup.
4. A scanning electron microscope electron detector with high collection efficiency as claimed in claim 1, wherein: the scintillator is specifically a P47 scintillator, a YAG scintillator or a YAP scintillator.
5. A scanning electron microscope electron detector with high collection efficiency as claimed in claim 1, wherein: the axial front end of the photomultiplier is a signal input end, the axial rear end of the photomultiplier is provided with the high-voltage power supply, and the side of the axial region of the photomultiplier is provided with a current amplification circuit board.
6. A scanning electron microscope electron detector with high collection efficiency as claimed in claim 3, wherein: the stainless steel shell comprises a rear end shell, a middle connecting piece and a front end shell, wherein a high-voltage power supply, a current amplification circuit board and a photomultiplier are wrapped in the rear end shell, the middle connecting piece is used for connecting the rear end shell and the front end shell, an axial inner cavity formed by the front end shell and the middle connecting piece is wrapped with a light guide pillar, a scintillator and a gem gasket, the axial front part of the front end shell is provided with the Faraday cup, and an electronic signal input end of the Faraday cup is exposed out of the front end shell and fixedly provided with a screen.
7. A scanning electron microscope electron detector with high collection efficiency as claimed in claim 1, wherein: the screen surface of the screen is arranged in a forward convex mode.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202121659108.3U CN216054568U (en) | 2021-07-21 | 2021-07-21 | Scanning electron microscope electronic detector with high collection efficiency |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202121659108.3U CN216054568U (en) | 2021-07-21 | 2021-07-21 | Scanning electron microscope electronic detector with high collection efficiency |
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| Publication Number | Publication Date |
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| CN216054568U true CN216054568U (en) | 2022-03-15 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
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| CN202121659108.3U Active CN216054568U (en) | 2021-07-21 | 2021-07-21 | Scanning electron microscope electronic detector with high collection efficiency |
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- 2021-07-21 CN CN202121659108.3U patent/CN216054568U/en active Active
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