Ultrafast and efficient electron detectors based on nano-polycrystalline boron nitride

Abstract

The present invention relates to the field of electron detectors and discloses an ultrafast, high-efficiency electron detector based on nano-polycrystalline boron nitride. The detector comprises a nano-polycrystalline boron nitride scintillator, a light guide, and a photomultiplier tube. The nano-polycrystalline boron nitride scintillator and the photomultiplier tube are connected to the front and rear ends of the light guide, respectively. The nano-polycrystalline boron nitride material of the nano-polycrystalline boron nitride scintillator is produced by epitaxial growth in a chemical vapor deposition furnace using a sapphire single crystal wafer as a substrate and NH3 and BCl3, or NH3 and BF3, as raw material gases. In the present invention, the nano-polycrystalline boron nitride scintillator has a short electron decay time and a high scintillation light yield. When used in an electron detector, it can achieve ultrafast and high-efficiency electron radiation detection. The electron detector of the present invention can be used for secondary electron and backscattered electron detection in electron beam detection systems, providing a new option for electron beam detection technology.

Description

Technical Field

[0001] The present invention relates to the field of electronic detectors, and in particular to an ultrafast and efficient electronic detector based on nano-polycrystalline boron nitride. Background Art

[0002] Semiconductor wafer inspection technology is a crucial step in ensuring the quality and performance of semiconductor devices. It not only detects physical defects on the wafer surface but also involves the precise measurement of critical dimensions. Electron beam inspection technology, with its high precision and high resolution, plays an irreplaceable role in this field. For example, electron beam defect inspection (EBI) equipment can detect defects in semiconductor wafers in real time, particularly electrical defects in internal circuits. Critical dimension scanning electron microscopy (CD-SEM) monitors key process parameters by measuring critical dimensions using electron beam microscopic images.

[0003] In these electron beam detection systems, electron detectors convert secondary electrons or backscattered electron signals into visible light signals for detection. Electron scintillators are key components for efficient electron detection. They need to have the following characteristics: high light yield to ensure sufficient signal intensity, short decay time to achieve fast signal response, low afterglow to avoid image tailing, and excellent radiation resistance to maintain long-term stability. Currently, the commonly used electron scintillating materials are YAG:Ce (Ce-doped Y3Al5O 12 ) and YAP:Ce (Ce-doped YAlO3) single crystals. These materials are widely used due to their relatively simple preparation process and low cost. However, most YAG:Ce scintillators used to date suffer from long decay times and high afterglow, which limits their performance in certain fast, high-precision applications. YAP:Ce scintillators have a fast decay capability of approximately 30ns, which can improve electron detection efficiency. Nevertheless, in order to further promote the advancement of electron beam detection technology and expand its applications, the continuous exploration and development of new electron scintillators remains of great significance. Summary of the Invention

[0004] In view of the above background technology, the present invention provides an ultrafast and efficient electron detector based on nano-polycrystalline boron nitride and a preparation method of nano-polycrystalline boron nitride, which has a shorter decay time and higher luminous efficiency than the existing YAP:Ce scintillator.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0006] In a first aspect, the present invention provides an ultrafast and efficient electron detector based on nano-polycrystalline boron nitride, comprising a nano-polycrystalline boron nitride scintillator, a light guide, and a photomultiplier tube, wherein the nano-polycrystalline boron nitride scintillator and the photomultiplier tube are connected to the front end and the rear end of the light guide, respectively;

[0007] The nano-polycrystalline boron nitride scintillator is used to receive electron irradiation and, under electron excitation, utilizes the carrier confinement effect of its nano-polycrystalline structure to produce nanosecond-level ultrafast and high-brightness scintillation light.

[0008] The nano-polycrystalline boron nitride scintillator is made of a sapphire single crystal wafer as a substrate, NH3 and BCl3, or NH3 and BF3 as raw material gases, and is epitaxially grown in a vertical chemical vapor deposition furnace.

[0009] The light guide is used to transmit the scintillation light to the photomultiplier tube;

[0010] The photomultiplier tube is used to receive the scintillation light transmitted by the light guide and record photon information.

[0011] Furthermore, the surface of the nano-polycrystalline boron nitride scintillator is plated with a layer of metal aluminum with a thickness of 50 to 60 nm using magnetron sputtering technology.

[0012] Furthermore, the electron detector also includes a Faraday cage device installed at the front end of the nano-polycrystalline boron nitride scintillator, which is used for secondary electron detection in the electron beam detection system.

[0013] Furthermore, a circular hole is opened in the center of the nano-polycrystalline boron nitride scintillator to form a circular ring structure, which is used for backscattered electron detection in an electron beam detection system.

[0014] Furthermore, the light guide is any one of quartz optical fiber, glass optical fiber or plastic optical fiber.

[0015] Furthermore, the nano-polycrystalline boron nitride scintillator is prepared by the following preparation method, which includes the following steps:

[0016] S1. Select a sapphire single crystal with a low lattice match to boron nitride as the substrate, and select an aluminum polar surface that is easy to nucleate as the growth surface;

[0017] S2. Fix the substrate with a graphite fixture and place the graphite fixture and substrate into a vertical chemical vapor deposition furnace. After evacuation, use lateral heating to reach the reaction temperature.

[0018] S3, NH3 and BCl3, or NH3 and BF3 raw material gases are introduced into the furnace, using N2 as the carrier gas;

[0019] S4. After ventilation, the gas flow rate is kept constant and the temperature is kept constant; finally, the power is turned off and the furnace is cooled, and the boron nitride / sapphire is taken out of the furnace at room temperature, and the boron nitride automatically falls off to obtain a nano-polycrystalline boron nitride material;

[0020] S5. Cut the nano-polycrystalline boron nitride material into a preset size according to the detector requirements to obtain a nano-polycrystalline boron nitride scintillator.

[0021] Furthermore, step S5 of the method for preparing the nano-polycrystalline boron nitride scintillator further includes depositing metal aluminum with a thickness of 50 to 60 nm on the surface of the nano-polycrystalline boron nitride material by magnetron sputtering, and then cutting it into a preset size.

[0022] Furthermore, in step S2 of the method for preparing the nano-polycrystalline boron nitride scintillator, lateral heating is used to a reaction temperature of 1300-1600° C. after vacuuming.

[0023] Furthermore, in step S3 of the method for preparing the nano-polycrystalline boron nitride scintillator, the gas volume ratio of the raw material gases NH3 and BCl3, or NH3 and BF3, is controlled to be 1.2-1.5:1.

[0024] Furthermore, in step S4 of the method for preparing the nano-polycrystalline boron nitride scintillator (1), the temperature is maintained at 1300-1600° C. after ventilation, and the temperature is maintained for 240-360 minutes.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. Compared with YAP:Ce single crystals, the nano-polycrystalline boron nitride of the present invention has a shorter luminescence decay time and a faster response speed. This fast response characteristic helps reduce image blur during electron beam imaging, thereby further improving image quality.

[0027] 2. Compared with YAP:Ce single crystal, the nano-polycrystalline boron nitride film of the present invention exhibits higher luminescence efficiency, and its maximum luminescence quantum yield can be as high as 39.8%. Therefore, it can be seen that the nano-polycrystalline boron nitride film of the present invention has excellent luminescence properties.

[0028] 3. In this invention, boron nitride scintillators, produced by vertical chemical vapor deposition epitaxial growth, are used in electron detectors. Because nano-polycrystalline boron nitride scintillators have short electron decay times and high scintillation light yields, the electron detectors constructed using nano-polycrystalline boron nitride can achieve ultrafast and efficient electron detection. The electron detectors of this invention can be used to detect secondary electrons and backscattered electrons in electron beam detection systems, providing a new option for electron beam detection technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic structural diagram of a nano-polycrystalline boron nitride electron scintillator electron detector according to Example 1 of the present invention;

[0030] Figure 2 This is a structural schematic diagram and imaging comparison diagram of an electron detector based on nano-polycrystalline boron nitride that can be used for secondary electron detection according to Example 2 of the present invention;

[0031] Figure 3 This is a structural schematic diagram and imaging comparison diagram of an electron detector based on nano-polycrystalline boron nitride that can be used for backscattered electron detection according to Example 3 of the present invention;

[0032] Figure 4 A physical image, growth diagram, and installation diagram of nano-polycrystalline boron nitride according to Example 4 of the present invention;

[0033] Figure 5 This is a result image of the cross-sectional structure of nano-polycrystalline boron nitride photographed using a transmission electron microscope in Example 5 of the present invention;

[0034] Figure 6 This is a graph showing the results of a comparative analysis of a nano-polycrystalline boron nitride scintillator and a commercial YAP:Ce scintillator under the same excitation conditions in Example 6 of the present invention.

[0035] In the picture:

[0036] 1-Nano-polycrystalline boron nitride scintillator; 2-Light guide; 3-Photomultiplier tube; 4-Faraday cage; 5-Circular aperture. DETAILED DESCRIPTION

[0037] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Example 1: Ultrafast and efficient electron detector based on nano-polycrystalline boron nitride

[0038] This embodiment is used to provide an ultrafast and efficient electron detector based on nano-polycrystalline boron nitride of the present invention. Figure 1 As shown, an ultrafast and efficient electron detector based on nano-polycrystalline boron nitride includes a nano-polycrystalline boron nitride scintillator 1, a light guide 2, and a photomultiplier tube 3. The nano-polycrystalline boron nitride scintillator 1 and the photomultiplier tube 3 are connected to the front end and the rear end of the light guide 2 respectively; wherein,

[0039] Nano-polycrystalline boron nitride scintillator 1, made by rapid film growth using high-temperature chemical vapor deposition, is used to receive electron irradiation and, under electron excitation, utilizes the carrier confinement effect of its nano-polycrystalline structure to produce nanosecond-level ultrafast, high-brightness scintillation light;

[0040] A light guide 2, for transmitting the scintillation light to the photomultiplier tube 3, wherein the light guide 2 is specifically one of quartz optical fiber, glass optical fiber or plastic optical fiber;

[0041] The photomultiplier tube 3 is used to receive the scintillation light transmitted by the light guide 2 and record photon information.

[0042] During operation, the nano-polycrystalline boron nitride scintillator 1 generates scintillation light after receiving electron irradiation, and the light guide 2 transmits the scintillation light to the photomultiplier tube 3. After receiving the scintillation light signal, the photomultiplier tube 3 records the photon information and reads it out.

[0043] To prevent charge accumulation on the surface of the nano-polycrystalline boron nitride scintillator 1 due to electron impact, this embodiment also uses magnetron sputtering technology to coat the surface of the nano-polycrystalline boron nitride scintillator 1 with a 50-60nm thick layer of aluminum. This aluminum layer not only effectively prevents charge accumulation but also serves as a reflective layer, reflecting the reverse-propagating scintillation light, thereby improving the scintillator's light output. Furthermore, in this embodiment, the nano-polycrystalline boron nitride scintillator 1 can be cut to a preset size based on the requirements of the electron detector.

[0044] Since the nano-polycrystalline boron nitride scintillator 1 has a short decay time and a high light yield, combined with the back-end design of the light guide 2 and the photomultiplier tube 3 matched therewith, the electronic detector of the present invention can achieve faster time resolution and higher detection efficiency.

[0045] Example 2: Electron detector based on nano-polycrystalline boron nitride for secondary electron detection

[0046] Based on Example 1, this example is used to provide a modified electron detector that can be used for secondary electron detection in an electron beam detection system.

[0047] Figure 2 a and Figure 2 b are the structural schematic diagram and imaging comparison diagram of the secondary electron detector based on nano-polycrystalline boron nitride in this embodiment. Figure 2As shown in a, based on Example 1, the electron detector that can be used for secondary electron detection in this embodiment also includes a Faraday cage device installed at the front end of the nano-polycrystalline boron nitride scintillator 1. Since the energy of secondary electrons is relatively weak, they are easily affected by the electric field and deflected. During the operation of the secondary electron detector, the Faraday cage with applied voltage can attract and accelerate scattered secondary electrons from all directions. Once these accelerated electrons hit the nano-polycrystalline boron nitride scintillator 1, they will cause it to emit light, and the generated scintillation light is then transmitted through the light guide 2 and finally collected and recorded by the photomultiplier tube 3. Since the nano-polycrystalline boron nitride of the present invention has faster and more efficient electron scintillation performance, compared with existing secondary electron detectors, the use of a secondary electron detector based on nano-polycrystalline boron nitride can significantly shorten the time for scanning electronic signals to obtain images, thereby achieving faster and more efficient detection of samples (see Figure 2 b).

[0048] Example 3: Electron detector based on nano-polycrystalline boron nitride for backscattered electron detection

[0049] Based on Example 1, this example is used to provide a modified electron detector that can be used for backscattered electron detection in an electron beam detection system.

[0050] Figure 3 a and Figure 3 b are the structural schematic diagram and imaging comparison diagram of the backscattered electron detector based on nano-polycrystalline boron nitride in this embodiment. Figure 3 As shown in a, based on Example 1, the electron detector of this embodiment can be used for backscattered electron detection, and a circular hole is opened in the center of the nano-polycrystalline boron nitride scintillator 1 to form a circular ring structure. The purpose of this geometric setting is to allow the incident electron beam to directly reach the sample surface, thereby exciting backscattered electrons. Although the incident electron beam can simultaneously excite secondary electrons and backscattered electrons, due to the low energy of secondary electrons, they will not produce significant scintillation light after reaching the backscattered electron detector, while high-energy backscattered electrons can effectively excite the scintillator to emit light. The light emitted by the scintillator is conducted through the light guide 2 and is also collected and recorded by the photomultiplier tube 3. Since nano-polycrystalline boron nitride has faster and more efficient electron scintillation performance, compared with existing backscattered electron detectors, the backscattered electron detector based on nano-polycrystalline boron nitride of this embodiment can significantly shorten the time for electronic signal scanning to obtain images, thereby achieving faster and more efficient detection of samples (see Figure 3 b).

[0051] Example 4: Preparation Method of Nano-Polycrystalline Boron Nitride Scintillator in Electronic Detector

[0052] This embodiment provides a method for preparing the nano-polycrystalline boron nitride scintillator used in the electron detectors described in Examples 1 to 3. In this embodiment, the nano-polycrystalline boron nitride is epitaxially grown using a 6-inch sapphire single crystal wafer as a substrate, using NH3 and BCl3 (or NH3 and BF3) as raw material gases, in a vertical chemical vapor deposition furnace. The preparation method of the nano-polycrystalline boron nitride material includes the following steps:

[0053] S1. Select a 6-inch sapphire single crystal with a low lattice match to boron nitride as the substrate, and select the aluminum polar surface that is easy to nucleate as the growth surface;

[0054] In this embodiment, since the aluminum polar surface of sapphire has a higher surface energy, which is conducive to adsorption and nucleation, the aluminum surface of the substrate is selected for the growth of nano-polycrystalline boron nitride.

[0055] S2. Use a graphite clamp to fix the substrate, and place the graphite clamp and the substrate into a vertical chemical vapor deposition furnace. After vacuuming, use lateral heating to the reaction temperature of 1500°C.

[0056] S3, feeding raw gas NH3 and BCl3 (or NH3 and BF3) into the furnace, using N2 as a carrier gas, so that the gas mixing reaction quickly generates boron nitride on the substrate and promotes its continuous growth; S4, maintaining the gas flow rate unchanged, and controlling the gas volume ratio of the raw gas NH3 and BCl3 (or NH3 and BF3) to 1.2:1 to promote the formation of boron nitride; after ventilation, the temperature is maintained at 1500°C and kept warm for 300 minutes, during which time, boron nitride grains nucleate on the sapphire substrate and gradually grow to form a nano-polycrystalline structure; finally, turning off the power and cooling, and the boron nitride / sapphire is taken out of the furnace at room temperature with the furnace cooling, and the boron nitride automatically falls off, thereby obtaining the nano-polycrystalline boron nitride material of the present invention;

[0057] S5. Depositing metallic aluminum with a thickness of 50 to 60 nm on the surface of the nano-polycrystalline boron nitride material by magnetron sputtering technology, and cutting the nano-polycrystalline boron nitride material into a preset size according to the requirements of the detector to obtain the nano-polycrystalline boron nitride scintillator of the present invention;

[0058] In this embodiment, the metallic aluminum can not only effectively prevent charge accumulation, but also serve as a reflective layer to reflect the scintillation light propagating in the opposite direction, thereby improving the light output capability of the scintillator.

[0059] S6. Install the trimmed nano-polycrystalline boron nitride scintillator at the front end of the light guide to obtain the nano-polycrystalline boron nitride-based electron detector of the present invention.

[0060] The growth diagram, physical diagram and installation diagram of the nano-polycrystalline boron nitride prepared in this embodiment are as follows: Figure 4 As shown, Figure 4a is a physical picture of nano-polycrystalline boron nitride. Figure 4 b is a schematic diagram of the growth of nano-polycrystalline boron nitride. Figure 4 Figure c is a schematic diagram of the installation of nano-polycrystalline boron nitride scintillator.

[0061] Example 5: Transmission Electron Microscope Analysis of the Cross-Sectional Structure of Nano-Polycrystalline Boron Nitride

[0062] The lattice matching between sapphire and boron nitride is low, and the boron nitride film reaches the micron level, which usually causes the grown boron nitride film to automatically fall off the sapphire substrate. The cross-sectional structure was photographed using a transmission electron microscope (TEM), and the results are as follows: Figure 5 As shown, Figure 5 a is a low magnification TEM image, Figure 5 b is the diffraction pattern of selected area electrons, Figure 5 c is a high-resolution TEM image.

[0063] Ideally, boron nitride should exhibit a layered structure. However, Figure 5 As shown in a, in the low-magnification TEM image, the structure of the grown boron nitride film appears to be relatively disordered. Figure 5 In b, the selected area electron diffraction pattern reveals that it mainly grows along the c-axis direction, with the main crystal plane being (002), showing polycrystalline characteristics. Through in-depth analysis of high-resolution TEM images, it can be seen that the atomic arrangement of the grown boron nitride film is not uniform, the lattice is distorted, and a nanocluster structure is formed (see Figure 5 c). Within localized nanoscale regions, boron nitride maintains an ordered layered structure, but overall exhibits polycrystalline properties, defined as a nano-polycrystalline (NP) structure. This structure is attributed, on the one hand, to the poor lattice matching between the boron nitride layer and the sapphire substrate, which leads to island-like growth; on the other hand, the use of a large reaction gas flow rate during the growth process accelerates the growth rate, resulting in uneven lattice alignment and localized distortion. Therefore, in this example, nano-polycrystalline boron nitride (NPBN) was successfully grown via chemical vapor deposition.

[0064] Example 6: Comparative Analysis of Nano-Polycrystalline Boron Nitride Scintillator and Commercial YAP:Ce Scintillator

[0065] Comparative analysis of electron beam imaging of nano-polycrystalline boron nitride (NPBN) film scintillator and commercial YAP:Ce single crystal scintillator under the same excitation conditions is shown in the following figure. Figure 6 As shown, Figure 6 a is the luminescence time response of NPBN and YAP:Ce under the same excitation conditions, Figure 6 b is the result of the comparison of luminescence quantum yield. Figure 6 c and Figure 6d are the results of grayscale photos of the scintillation luminescence of NPBN and YAP:Ce under 2MeV electron beam excitation. Figure 6 e and Figure 6 f are the simulations of electron penetration depth distribution of NPBN and YAP:Ce under 2MeV electron beam excitation.

[0066] As shown in the figure, the luminescence decay time of NPBN (9.4ns) is significantly shorter than that of YAP:Ce (40.6ns), showing a faster time response. This fast response characteristic helps reduce image blur during electron beam imaging and further improve image quality (see Figure 6 In addition, the peak wavelength of NPBN is around 385nm, which is similar to the peak wavelength of YAP:Ce, and similarly does not require the use of a photomultiplier tube with increased sensitivity in the long-wave region. Further luminescence quantum yield (PLQY) test results also confirmed that NPBN exhibits higher luminescence efficiency than YAP:Ce, with a maximum luminescence quantum yield of up to 39.8% (see Figure 6 b) The strong luminescence originates from the carrier confinement effect caused by the nano-polycrystalline structure of boron nitride. Because excited carriers are confined by the structure, they are more likely to radiatively recombine, thereby enhancing the luminescence ability. These results demonstrate the excellent luminescence properties of NPBN.

[0067] To further visualize the light yield from NPBN electron scintillation, this example captured luminescence images of NPBN and YAP:Ce scintillators under electron beam excitation. When an electron beam (with an energy of 2 MeV) strikes the scintillator perpendicularly, the generated light is first deflected 90° by a mirror and then captured by a camera. Luminescence images of the scintillators were captured while maintaining the same electron beam pulse frequency and camera integration time. Figure 6 c and Figure 6 Figures d and d show grayscale images of the blinking luminescence of 100 μm-thick NPBN and 500 μm-thick YAP:Ce, respectively. As shown, under the same excitation conditions, the 100 μm-thick NPBN exhibits higher contrast, that is, higher blinking light yield, compared to the 500 μm-thick commercial YAP:Ce.

[0068] Furthermore, this embodiment also uses Casino software to simulate the penetration depth of electron beam into NPBN and YAP:Ce scintillators under these conditions. The simulation results show that under these conditions, the electron beam can easily penetrate 100μm thick NPBN and 500μm thick YAP:Ce (see Figure 6 e and Figure 6 f). NPBN can maintain a high scintillation light yield even at thin thickness, which further confirms the great potential of NPBN as an electron scintillator.

[0069] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the application should be included in the scope of protection of the present application.

Claims

1. An ultrafast and efficient electron detector based on nano-polycrystalline boron nitride, characterized in that: The invention comprises a nano-polycrystalline boron nitride scintillator (1), a light guide (2), and a photomultiplier tube (3), wherein the nano-polycrystalline boron nitride scintillator (1) and the photomultiplier tube (3) are respectively connected to the front end and the rear end of the light guide (2); wherein: The nano-polycrystalline boron nitride scintillator (1) is used to receive electron irradiation and, under electron excitation, utilizes the carrier confinement effect of its nano-polycrystalline structure to generate nanosecond-level ultrafast high-brightness scintillating luminescence; The nano-polycrystalline boron nitride scintillator (1) is made of a sapphire single crystal wafer as a substrate, NH3 and BCl3, or NH3 and BF3 as raw material gases, and is produced by epitaxial growth in a vertical chemical vapor deposition furnace. The light guide (2) is used to transmit the scintillation light to the photomultiplier tube (3); The photomultiplier tube (3) is used to receive the scintillation light transmitted by the light guide (2) and record photon information; The nano-polycrystalline boron nitride scintillator (1) is prepared by the following preparation method, which comprises the following steps: S1. Select a sapphire single crystal with a low lattice match to boron nitride as the substrate, and select an aluminum polar surface that is easy to nucleate as the growth surface; S2. Fix the substrate with a graphite fixture and place the graphite fixture and substrate into a vertical chemical vapor deposition furnace. After evacuation, use lateral heating to reach the reaction temperature. S3, NH3 and BCl3, or NH3 and BF3 raw material gases are introduced into the furnace, using N2 as the carrier gas; S4. After ventilation, the gas flow rate is kept constant and the temperature is kept constant; finally, the power is turned off and the furnace is cooled, and the boron nitride / sapphire is taken out of the furnace at room temperature, and the boron nitride automatically falls off to obtain a nano-polycrystalline boron nitride material; S5. Cut the nano-polycrystalline boron nitride material into a preset size according to the detector requirements to obtain a nano-polycrystalline boron nitride scintillator.

2. The ultrafast and efficient electron detector based on nano-polycrystalline boron nitride according to claim 1, characterized in that: The surface of the nano-polycrystalline boron nitride scintillator (1) is plated with a layer of metal aluminum with a thickness of 50 to 60 nm using magnetron sputtering technology.

3. The ultrafast and efficient electron detector based on nano-polycrystalline boron nitride according to claim 1, characterized in that: The electron detector further comprises a Faraday cage device (4) installed at the front end of the nano-polycrystalline boron nitride scintillator (1) and used for secondary electron detection in an electron beam detection system.

4. The ultrafast and efficient electron detector based on nano-polycrystalline boron nitride according to claim 1, characterized in that: A circular hole (5) is provided at the center of the nano-polycrystalline boron nitride scintillator (1), forming a circular ring structure, which is used for backscattered electron detection in an electron beam detection system.

5. The ultrafast and efficient electron detector based on nano-polycrystalline boron nitride according to claim 1, characterized in that: The light guide (2) is any one of a quartz optical fiber, a glass optical fiber or a plastic optical fiber.

6. The ultrafast and efficient electron detector based on nano-polycrystalline boron nitride according to claim 1, characterized in that: Step S5 of the method for preparing the nano-polycrystalline boron nitride scintillator (1) further comprises depositing metal aluminum with a thickness of 50 to 60 nm on the surface of the nano-polycrystalline boron nitride material by magnetron sputtering, and then cutting the metal aluminum into a preset size.

7. The ultrafast and efficient electron detector based on nano-polycrystalline boron nitride according to claim 1, characterized in that: In step S2 of the method for preparing the nano-polycrystalline boron nitride scintillator (1), lateral heating is performed to a reaction temperature of 1300-1600° C. after vacuuming.

8. The ultrafast and efficient electron detector based on nano-polycrystalline boron nitride according to claim 1, characterized in that: In step S3 of the method for preparing the nano-polycrystalline boron nitride scintillator (1), the gas volume ratio of the raw material gases NH3 and BCl3, or NH3 and BF3, is controlled to be 1.2-1.5:

1.

9. The ultrafast and efficient electron detector based on nano-polycrystalline boron nitride according to claim 1, characterized in that: In step S4 of the method for preparing the nano-polycrystalline boron nitride scintillator (1), the temperature is maintained at 1300-1600° C. after ventilation, and the temperature is maintained for 240-360 minutes.

Images