Secondary electron detection method and system in scanning electron microscope barrel

Abstract

The present invention discloses a method and system for detecting secondary electrons in the lens barrel of a scanning electron microscope, wherein an accelerating electrode and a secondary electron detector are sequentially arranged in the lens barrel from bottom to top, and an electrode cover is arranged outside the secondary electron detector, and the method comprises: applying a first voltage to the accelerating electrode to form a first pressure difference that absorbs secondary electrons generated on the surface of a sample into the lens barrel; applying a second voltage to the electrode cover to slowly accelerate the secondary electrons entering the lens barrel to have an energy corresponding to the second voltage so as to enter the secondary electron detector for detection. The detection method of the present invention solves the problem that the secondary electron detector in the lens barrel cannot be used for imaging energies above 20 kV in current equipment by only introducing the first voltage and the second voltage for synergistic action without changing the structure of the overall system of the electron microscope, and at the same time enables the secondary electrons to have sufficient energy to enter the secondary electron detector for detection.

Description

Technical Field

[0001] The invention relates to the technical field of scanning electron microscope imaging, and in particular to a secondary electron detection method and system in a scanning electron microscope barrel. Background Art

[0002] Secondary electrons refer to electrons emitted from the surface of an object within a depth range of 5 to 10 nm when the surface of the object is bombarded by electron flow or ion flow. 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 displayed very effectively. 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 is also used in electronic imaging elements such as scanning electron microscopes.

[0003] When a scanning electron microscope collects secondary electrons for imaging, in order to improve the imaging resolution, it is usually possible to reasonably design to only collect secondary electrons emitted from the sample surface and filter out secondary electrons generated in the sample cavity and other areas. The secondary electrons generated by the sample are accelerated into the lens barrel in the reverse direction, and change their trajectories under the magnetic field of the objective lens, enter the lens barrel and are detected by the secondary electron detector.

[0004] In the existing secondary electron detection schemes in the telescope, such as Figure 1 As shown in the figure, the sample is grounded and the electrodes in the lens barrel are usually added with a positive high voltage of 8kV. Under this design, the secondary electrons generated on the sample surface are reversely accelerated to 8kV and enter the lens barrel under the joint action of the objective lens magnetic field to be detected by the secondary electron detector. The role of adding a positive high voltage of 8kV is to: 1. Generate a reverse accelerating electric field between the sample and the lens barrel, sucking the secondary electrons on the sample surface into the lens barrel for detection; 2. Make the secondary electrons obtain enough energy (8kV) to hit the detector to obtain a signal of sufficient intensity.

[0005] However, when the imaging energy exceeds 20kV, it is difficult to add an 8kV acceleration voltage in the lens barrel in engineering. Since the voltage difference between the accelerating anode and the accelerating electrode of the lens barrel exceeds 28kV, there is a risk of discharge and creepage, which increases the instability of the system. If the acceleration voltage is not added to the lens barrel, the secondary electrons cannot enter the lens barrel; if the acceleration voltage in the lens barrel is less than 8kV, the electrons do not have enough energy to be detected, and a signal of sufficient intensity cannot be obtained. Therefore, it is difficult for existing detection schemes to achieve secondary electron detection when the imaging energy exceeds 20kV. Summary of the invention

[0006] In order to overcome the deficiencies of the prior art, the object of the present invention is to provide a method and system for detecting secondary electrons in the barrel of a scanning electron microscope, which can realize efficient detection of secondary electrons in the barrel with imaging energy exceeding 20 kV.

[0007] The purpose of the present invention is achieved by the following technical solutions:

[0008] According to a first aspect of an embodiment of the present disclosure, a method for detecting secondary electrons in a scanning electron microscope barrel is provided, wherein an accelerating electrode and a secondary electron detector are sequentially arranged in the barrel from bottom to top, and an electrode cover is arranged outside the secondary electron detector, and the method comprises:

[0009] Applying a first voltage to the accelerating electrode to form a first pressure difference to draw secondary electrons generated on the sample surface into the lens barrel;

[0010] A second voltage is applied to the electrode cover to slowly accelerate the secondary electrons entering the lens barrel to have energy corresponding to the second voltage so as to enter the secondary electron detector for detection. A second pressure difference is formed between the sample and the electrode cover, and the first pressure difference is smaller than the second pressure difference.

[0011] To implement the above technical solution, a first voltage is applied to the accelerating electrode to form a first pressure difference. Since the first pressure difference is small, the secondary electrons generated on the sample surface can be sucked into the lens barrel while ensuring that the pressure difference in the lens barrel remains basically unchanged. A second voltage is applied to the electrode cover to form a second pressure difference, so that the secondary electrons will be slowly accelerated to the energy value corresponding to the second pressure difference after entering the lens barrel, that is, they can obtain sufficient energy to enter the detector for detection. The detection method of the present invention solves the problem that the secondary electron detector in the lens barrel cannot be used for imaging energies above 20 kV in current equipment by only introducing the first voltage and the second voltage for synergistic effect without changing the overall system structure of the electron microscope, and at the same time enables the secondary electrons to have sufficient energy to enter the secondary electron detector for detection. At the same time, this solution can also solve the problem of insufficient secondary electron energy when the scanning electron microscope works in the sample deceleration mode and there is no acceleration in the lens barrel.

[0012] In some exemplary embodiments, the first voltage difference is greater than 0.5 kV, and the second voltage difference is 7-10 kV.

[0013] In some exemplary embodiments, the lens barrel is further provided with an electron generator, an extraction electrode, a condenser, a scanning coil and an objective lens from top to bottom, the secondary electron detector is located between the condenser and the scanning coil, and the accelerating electrode extends from the objective lens to below the extraction electrode; the method further comprises:

[0014] The electron generator generates an incident electron beam and emits it toward the sample to be tested, and the incident electron beam is extracted by the extraction electrode and then converged by a condenser;

[0015] The scanning coil deflects the incident electron beam to scan the sample to be tested and generates the secondary electrons.

[0016] The above technical solution is implemented to realize the generation of an incident electron beam and the production of secondary electrons for scanning detection of the sample to be tested. Moreover, since the secondary electron detector is usually far away from the accelerating electrode, the lens effect formed by applying an accelerating voltage of 8 kV to the secondary electron detector is very weak. For the case where the imaging energy is above 20 kV, the impact on the incident electron beam for downward imaging is also smaller.

[0017] According to a second aspect of an embodiment of the present disclosure, a secondary electron detection system in a scanning electron microscope barrel is provided, comprising:

[0018] An accelerating electrode is arranged in the lens barrel near the side of the sample to be measured, and the accelerating electrode is connected to a first pressurizing device, and the first pressurizing device is used to apply a first voltage to the accelerating electrode to form a first pressure difference to absorb secondary electrons generated on the sample surface into the lens barrel; and

[0019] A secondary electron detector is arranged in the lens barrel, an electrode cover is arranged near the outside of the secondary electron detector, and the electrode cover is located below the secondary electron detector and has a channel for secondary electrons to enter, the electrode cover is connected to a second pressurizing device, the second pressurizing device is used to apply a second voltage to the electrode cover to slowly accelerate the secondary electrons entering the lens barrel to have energy corresponding to the second voltage so as to enter the secondary electron detector for detection, a second pressure difference is formed between the sample and the electrode cover, and the first pressure difference is less than the second pressure difference.

[0020] To implement the above technical solution, a first voltage is applied to the accelerating electrode through a first pressure-applying device to form a first pressure difference. Since the first pressure difference is relatively small, it can ensure that the pressure difference in the lens barrel remains basically unchanged while the secondary electrons generated on the sample surface are sucked into the lens barrel. A second voltage is applied to the electrode cover to form a second pressure difference. In this way, after the secondary electrons enter the lens barrel, they will be slowly accelerated to the energy value corresponding to the second pressure difference, that is, they can obtain sufficient energy to enter the detector for detection. The detection method of the present invention solves the problem that the secondary electron detector in the lens barrel cannot be used for imaging energies above 20 kV in current equipment by only introducing the first voltage and the second voltage for synergistic effect without changing the overall system structure of the electron microscope. At the same time, it enables the secondary electrons to have sufficient energy to enter the secondary electron detector for detection.

[0021] In some exemplary embodiments, the first voltage difference is greater than 0.5 kV, and the second voltage difference is 7-10 kV.

[0022] In some exemplary embodiments, the electrode cover is disposed on the secondary electron detector in a semi-enclosed shape.

[0023] In some exemplary embodiments, the electrode cover is located below the secondary electron detector and is provided with an electrode mesh.

[0024] In some exemplary embodiments, the lens barrel is further provided with an electron generator, an extraction electrode, a condenser, a scanning coil and an objective lens from top to bottom, the secondary electron detector is located between the condenser and the scanning coil, and the acceleration electrode extends from the objective lens to below the extraction electrode;

[0025] The electron generator is used to generate an incident electron beam and emit it toward the sample to be tested;

[0026] The extraction electrode is used to extract the incident electron beam into the lens barrel;

[0027] The condenser is used to converge the incident electron beam;

[0028] The scanning coil is used to deflect the incident electron beam to scan the sample to be tested and generate the secondary electrons;

[0029] The objective lens is used to receive and focus the secondary electrons.

[0030] To implement the above technical solution, the incident electron beam is generated by an electron generator, and the scanning coil deflects the incident electron beam to generate secondary electrons for scanning detection of the sample to be tested. Since the secondary electron detector is usually far away from the accelerating electrode, the lens effect formed by adding an accelerating voltage of 8kV to the secondary electron detector is very weak. For the case where the imaging energy is above 20kV, the image of the incident electron beam for downward imaging is also smaller.

[0031] In some exemplary embodiments, a deceleration pole is further provided between the objective lens and the sample, and the deceleration pole is at the same pressure as the sample.

[0032] By implementing the above technical solution and setting a deceleration pole, it is possible to shield the messy electrons and improve the imaging effect.

[0033] In some exemplary embodiments, the secondary electron detector is further connected to an imaging system, and the secondary electron detector receives the secondary electrons to detect the sample to be tested, and forms a detection signal to be sent to the imaging system for imaging.

[0034] By implementing the above technical solution, the sample can be imaged by receiving the detection signal formed by the secondary electron detector through the imaging system.

[0035] In summary, compared with the prior art, the present invention has the following beneficial effects:

[0036] An embodiment of the present invention provides a method and system for detecting secondary electrons in a scanning electron microscope barrel, wherein an accelerating electrode and a secondary electron detector are sequentially arranged in the barrel from bottom to top, and an electrode cover is arranged outside the secondary electron detector. The method comprises: applying a first voltage to the accelerating electrode to form a first pressure difference that absorbs secondary electrons generated on a sample surface into the barrel; applying a second voltage to the electrode cover to slowly accelerate the secondary electrons entering the barrel to have energy corresponding to the second voltage so as to enter the secondary electron detector for detection, and a second pressure difference is formed between the sample and the electrode cover, and the first pressure difference is smaller than the second pressure difference. A first voltage is applied to the accelerating electrode to form a first pressure difference. Since the first pressure difference is small, the secondary electrons generated on the sample surface can be sucked into the lens barrel while ensuring that the pressure difference in the lens barrel remains basically unchanged. A second voltage is applied to the electrode cover to form a second pressure difference, so that the secondary electrons will be slowly accelerated to the energy value corresponding to the second pressure difference after entering the lens barrel, that is, they can obtain sufficient energy to enter the detector for detection. The detection method of the present invention solves the problem that the secondary electron detector in the lens barrel cannot be used for imaging energies above 20 kV in current equipment by only introducing the first voltage and the second voltage for synergistic effect without changing the overall system structure of the electron microscope, and at the same time enables the secondary electrons to have sufficient energy to enter the secondary electron detector for detection. At the same time, this solution can also solve the problem that the secondary electron energy is insufficient when the scanning electron microscope works in the sample deceleration mode and there is no acceleration in the lens barrel. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a structural schematic diagram of an existing secondary electron detection solution in a telescope barrel in the background technology of the present invention.

[0038] Figure 2 Schematic diagram of the structure of the lens barrel in the first embodiment of the present invention.

[0039] Figure 3 This is a flow chart of the detection method in Embodiment 1 of the present invention.

[0040] Figure 4 Schematic diagram of the structure of the lens barrel in the second embodiment of the present invention.

[0041] Figure 5 This is a flow chart of the detection method in Embodiment 2 of the present invention.

[0042] Figure 6 This is a schematic diagram of the structure of the third embodiment of the present invention.

[0043] Figure 7 This is a structural diagram of embodiment 4 of the present invention.

[0044] Figure 8This is a structural diagram of Embodiment 5 of the present invention.

[0045] Fig. 9 This is a structural diagram of embodiment 6 of the present invention.

[0046] The numbers and letters in the figure represent the corresponding component names:

[0047] 10. Mirror tube; 11. Accelerating electrode; 12. Secondary electron detector; 121. Electrode cover; 122. Electrode net; 13. Electron generator; 14. Extracting electrode; 15. Condenser; 16. Scanning coil; 17. Objective lens; 18. Decelerating electrode; 20. First pressurizing device; 30. Second pressurizing device; 40. Imaging system. DETAILED DESCRIPTION

[0048] The following will be combined with the 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 described embodiments 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 creative work are within the scope of protection of the present invention.

[0049] Embodiment 1

[0050] like Figure 2 and Figure 3 As shown, an embodiment of the present invention provides a method for detecting secondary electrons in a scanning electron microscope barrel, wherein an accelerating electrode 11 and a secondary electron detector 12 are sequentially arranged in the barrel 10 from bottom to top, and an electrode cover 121 is arranged outside the secondary electron detector 12. The method comprises:

[0051] S100, applying a first voltage to the accelerating electrode 11 to form a first pressure difference for sucking secondary electrons generated on the sample surface into the lens barrel 10, wherein the first pressure difference is greater than 0.5 kV, and in this embodiment, the first pressure difference is preferably 1 kV.

[0052] S200. A second voltage is applied to the electrode cover 121 so that the secondary electrons entering the lens barrel 10 are slowly accelerated to have energy corresponding to the second voltage so as to enter the secondary electron detector 12 for detection. A second pressure difference is formed between the sample and the electrode cover 121. The second pressure difference is 7-10 kV. In this embodiment, it is preferably set to 8 kV. In other embodiments, it can also be set to 10 kV to obtain a larger energy for the secondary electrons when entering the secondary electron detector 12.

[0053] The embodiment of the present invention forms a first pressure difference by applying a first voltage to the accelerating electrode 11. Since the first pressure difference is small, it can ensure that the pressure difference in the lens barrel 10 remains basically unchanged while realizing the absorption of the secondary electrons generated on the sample surface into the lens barrel 10. A second voltage is applied to the electrode cover 121 to form a second pressure difference. In this way, after the secondary electrons enter the lens barrel 10, they will be slowly accelerated to the energy value corresponding to the second pressure difference, that is, they can obtain sufficient energy to enter the detector for detection. The detection method of the present invention solves the problem that the current equipment cannot use the secondary electron detector 12 in the lens barrel 10 with an imaging energy of more than 20 kV by only introducing the first voltage and the second voltage for synergistic effect without changing the overall system structure of the electron microscope. At the same time, it can enable the secondary electrons to have sufficient energy to enter the secondary electron detector 12 for detection.

[0054] Embodiment 2

[0055] The embodiment of the present invention provides a method for detecting secondary electrons in a scanning electron microscope barrel, such as Figure 4 and Figure 5 As shown, the difference between this embodiment and the first embodiment is that: in this embodiment, the lens barrel 10 is further provided with an electron generator 13, an extraction electrode 14, a condenser lens 15, a scanning coil 16 and an objective lens 17 from top to bottom, the secondary electron detector 12 is located between the condenser lens 15 and the scanning coil 16, and the acceleration electrode 11 extends from the objective lens 17 to below the extraction electrode 14; the method comprises:

[0056] S100 , the electron generator 13 generates an incident electron beam and emits it toward the sample to be tested. The incident electron beam is extracted by the extraction electrode 14 and then converged by the condenser 15 .

[0057] S200, the scanning coil 16 deflects the incident electron beam to scan the sample to be tested and generates secondary electrons.

[0058] S300, applying a first voltage to the accelerating electrode 11 to form a first pressure difference for sucking secondary electrons generated on the sample surface into the lens barrel 10, wherein the first pressure difference is greater than 0.5 kV, and in this embodiment, the first pressure difference is preferably 1 kV.

[0059] S400, a second voltage is applied to the electrode cover 121 so that the secondary electrons entering the lens barrel 10 are slowly accelerated to have energy corresponding to the second voltage so as to enter the secondary electron detector 12 for detection. A second pressure difference is formed between the sample and the electrode cover 121. The second pressure difference is 7-10kV. In this embodiment, it is preferably set to 8kV. In other embodiments, it can also be set to 10kV to obtain a larger energy for the secondary electrons when entering the secondary electron detector 12.

[0060] In the embodiment of the present invention, the electron generator 13 realizes the generation of the incident electron beam and the generation of secondary electrons for scanning detection of the sample to be tested. Since the secondary electron detector 12 is usually far away from the accelerating electrode 11, the lens effect formed by adding an acceleration voltage of 8kV to the secondary electron detector 12 is very weak. When the imaging energy is above 20kV, the image of the incident electron beam for downward imaging is also smaller.

[0061] The following is a specific example:

[0062] When imaging, the electron generator 13 emits an incident electron beam with a voltage of -30kV. A voltage of -27kV is applied to the extraction electrode 14, and the incident electron beam is extracted by the extraction electrode 14 and emitted to the sample. After convergence by the condenser 15, the sample is scanned after deflection by the scanning coil 16 to form secondary electrons that are reflected back to the objective lens 17. The sample is grounded. At this time, the voltage of the sample is 0kV. 1kV is applied to the acceleration electrode 11, and a first voltage difference of 1kV is formed between the sample and the acceleration electrode 11, and the secondary electrons are sucked into the lens barrel 10, while the voltage difference between the extraction electrode 14 and the acceleration electrode 11 remains basically unchanged. A voltage of 8kV is applied to the electrode cover 121, and a second voltage difference of 7kV is formed between the electrode cover 121 and the sample. At this pressure difference, the secondary electrons will gradually accelerate to an energy of 8kV and then be emitted into the secondary electron detector 12 and detected.

[0063] And in another example:

[0064] In the solution of the sample deceleration mode, the electron generator 13 also emits an incident electron beam with a voltage of -30kV. A voltage of -27kV is applied to the extraction electrode 14, and the incident electron beam is extracted by the extraction electrode 14 and emitted to the sample. After the condenser 15 converges, it is deflected by the scanning coil 16 to scan the sample to form secondary electrons that are reflected back to the objective lens 17. At this time, the sample is connected to a voltage of -5kV, and no voltage is applied to the accelerating electrode 11, that is, a voltage of 0kV. A first pressure difference of 5kV is formed between the sample and the accelerating electrode 11, and the secondary electrons are sucked into the lens barrel 10. A voltage of 3kV is applied to the electrode cover 121. At this time, a second pressure difference of 8kV is formed between the electrode cover 121 and the sample. At this pressure difference, the secondary electrons will gradually accelerate to an energy of 8kV and then be emitted into the secondary electron detector 12 and detected. That is, the present invention can also solve the problem of insufficient secondary electron energy when the scanning electron microscope works in the sample deceleration mode and there is no acceleration in the lens barrel.

[0065] Embodiment 3

[0066] like Figure 6As shown, an embodiment of the present invention provides a secondary electron detection system in a scanning electron microscope barrel, comprising: an accelerating electrode 11 arranged in the barrel 10 near a side of a sample to be measured, the accelerating electrode 11 being connected to a first pressurizing device 20, the first pressurizing device 20 being used to apply a first voltage to the accelerating electrode 11 to form a first pressure difference that absorbs secondary electrons generated on the sample surface into the barrel 10, wherein the first pressure difference is greater than 0.5 kV, and in this embodiment, the first pressure difference is preferably 1 kV; and a secondary electron detector 12 arranged in the barrel 10, wherein an electrode cover 121 is provided near the secondary electron detector 12, and the electrode cover 121 A channel for secondary electrons to enter is provided below the secondary electron detector 12. The electrode cover 121 is connected to a second pressurizing device 30. The second pressurizing device 30 is used to apply a second voltage to the electrode cover 121 so that the secondary electrons entering the lens barrel 10 are slowly accelerated to have energy corresponding to the second voltage so as to enter the secondary electron detector 12 for detection. A second pressure difference is formed between the sample and the electrode cover 121. The second pressure difference is 7-10 kV. In this embodiment, it is preferably set to 8 kV. In other embodiments, it can also be set to 10 kV to obtain a larger energy for the secondary electrons when entering the secondary electron detector 12.

[0067] Among them, the electrode cover 121 is semi-enclosed and arranged on the secondary electron detector 12, and the position below the secondary electron detector 12 is an opening. After the secondary electrons are accelerated by the electrode cover 121, they can enter the secondary electron detector 12 from the opening and be detected; in other embodiments, an electrode mesh 122 can be further arranged at the bottom of the electrode cover 121, and the duty cycle of the electrode mesh 122 is greater than 80%. The secondary electrons can be accelerated more thoroughly by the electrode mesh 122, and at the same time, the larger gaps on the electrode mesh 122 will not affect the secondary electrons entering the secondary electron detector 12 and being detected.

[0068] In the embodiment of the present invention, a first voltage is applied to the accelerating electrode 11 by a first pressurizing device 20 to form a first pressure difference. Since the first pressure difference is relatively small, the secondary electrons generated on the sample surface can be sucked into the lens barrel 10 while ensuring that the pressure difference in the lens barrel 10 remains basically unchanged. A second voltage is applied to the electrode cover 121 to form a second pressure difference. In this way, after the secondary electrons enter the lens barrel 10, they will be slowly accelerated to the energy value corresponding to the second pressure difference, that is, they can obtain sufficient energy to enter the detector for detection. The detection method of the present invention solves the problem that the secondary electron detector 12 in the lens barrel 10 cannot be used for imaging energies above 20 kV in current equipment by only introducing the first voltage and the second voltage for synergistic effect without changing the overall system structure of the electron microscope. At the same time, it can enable the secondary electrons to have sufficient energy to enter the secondary electron detector 12 for detection.

[0069] Embodiment 4

[0070] The embodiment of the present invention provides a secondary electron detection system in a scanning electron microscope barrel, such as Figure 7 As shown, the difference between this embodiment and the third embodiment is that: in this embodiment, the lens barrel 10 is further provided with an electron generator 13, an extraction electrode 14, a condenser 15, a scanning coil 16 and an objective lens 17 from top to bottom, the secondary electron detector 12 is located between the condenser 15 and the scanning coil 16, and the accelerating electrode 11 extends from the objective lens 17 to below the extraction electrode 14; the electron generator 13 is used to generate an incident electron beam and emit it to the sample to be tested; the extraction electrode 14 is used to extract the incident electron beam into the lens barrel 10; the condenser 15 is used to converge the incident electron beam; the scanning coil 16 is used to deflect the incident electron beam to scan the sample to be tested and generate secondary electrons; the objective lens 17 is used to receive and converge the secondary electrons.

[0071] The electrode cover 121 is semi-enclosed on the secondary electron detector 12 , and its position below the secondary electron detector 12 is an opening. After being accelerated by the electrode cover 121 , the secondary electrons can enter the secondary electron detector 12 through the opening to be detected.

[0072] Furthermore, a deceleration pole 18 is provided between the objective lens 17 and the sample. The deceleration pole 18 is at the same voltage as the sample. For example, when the sample is grounded, its voltage is 0 kV. At this time, the voltage set on the deceleration pole 18 is also 0 kV. By setting the deceleration pole 18, chaotic electrons can be shielded and the imaging effect can be improved.

[0073] The embodiment of the present invention realizes the generation of an incident electron beam through the electron generator 13, and the scanning coil 16 deflects the incident electron beam to generate secondary electrons for scanning detection of the sample to be tested. Since the secondary electron detector 12 is usually far away from the accelerating electrode 11, the lens effect formed by adding an acceleration voltage of 8kV to the secondary electron detector 12 is very weak. When the imaging energy is above 20kV, the image of the incident electron beam for downward imaging is also smaller.

[0074] Embodiment 5

[0075] The embodiment of the present invention provides a secondary electron detection system in a scanning electron microscope barrel, such as Figure 8 As shown, the difference between this embodiment and the third embodiment is that in this embodiment, an electrode mesh 122 is arranged at the bottom of the electrode cover 121, and the duty cycle of the electrode mesh 122 is greater than 80%. The secondary electrons can be accelerated more thoroughly by the electrode mesh 122. At the same time, the larger gaps on the electrode mesh 122 will not affect the secondary electrons entering the secondary electron detector 12 for detection.

[0076] Embodiment 6

[0077] The embodiment of the present invention provides a secondary electron detection system in a scanning electron microscope barrel, such as Fig. 9 As shown, the difference between this embodiment and embodiment four is that: in this embodiment, the secondary electron detector 12 is also connected to an imaging system 40, the secondary electron detector 12 receives secondary electrons to detect the sample to be tested, and forms a detection signal to send to the imaging system 40 for imaging, wherein, in this embodiment, the imaging system 40 is used to receive the detection signal and process the image, and the sample can be imaged by receiving the detection signal formed by the secondary electron detector 12 through the imaging system 40.

[0078] The above embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which are equivalent modifications and improvements made to the above embodiments based on the essential technology of the present invention, and all of them belong to the protection scope of the present invention.

Claims

1. A method for detecting secondary electrons in a scanning electron microscope barrel, characterized in that: An accelerating electrode and a secondary electron detector are sequentially arranged in the lens barrel from bottom to top, and an electrode cover is arranged outside the secondary electron detector. The method comprises: Applying a first voltage to the accelerating electrode to form a first pressure difference to draw secondary electrons generated on the sample surface into the lens barrel; A second voltage is applied to the electrode cover to slowly accelerate the secondary electrons entering the lens barrel to have an energy corresponding to the second voltage so as to enter the secondary electron detector for detection, and a second pressure difference is formed between the sample and the electrode cover, and the first pressure difference is smaller than the second pressure difference; The first voltage difference is 0.5-1 kV, and the second voltage difference is 7-10 kV; The lens barrel is also provided with an electron generator, an extraction electrode, a condenser, a scanning coil and an objective lens from top to bottom, the secondary electron detector is located between the condenser and the scanning coil, and the acceleration electrode extends from the objective lens to below the extraction electrode; the method further comprises: The electron generator generates an incident electron beam and emits it toward the sample to be tested, and the incident electron beam is extracted by the extraction electrode and then converged by a condenser; The scanning coil deflects the incident electron beam to scan the sample to be tested and generates the secondary electrons.

2. A secondary electron detection system in a scanning electron microscope barrel, characterized in that: include: An accelerating electrode disposed in the lens barrel near a side of the sample to be measured, the accelerating electrode being connected to a first pressurizing device, the first pressurizing device being used to apply a first voltage to the accelerating electrode to form a first pressure difference to absorb secondary electrons generated on the sample surface into the lens barrel; as well as, A secondary electron detector is arranged in the lens barrel, an electrode cover is arranged outside the secondary electron detector, and the electrode cover is located below the secondary electron detector and has a passage for secondary electrons to enter, the electrode cover is connected to a second pressurizing device, the second pressurizing device is used to apply a second voltage to the electrode cover so that the secondary electrons entering the lens barrel are slowly accelerated to have an energy corresponding to the second voltage so as to enter the secondary electron detector for detection, a second pressure difference is formed between the sample and the electrode cover, and the first pressure difference is less than the second pressure difference; The first voltage difference is 0.5-1 kV, and the second voltage difference is 7-10 kV; The lens barrel is also provided with an electron generator, an extraction electrode, a condenser, a scanning coil and an objective lens from top to bottom, the secondary electron detector is located between the condenser and the scanning coil, and the acceleration electrode extends from the objective lens to below the extraction electrode; The electron generator is used to generate an incident electron beam and emit it toward the sample to be tested; The extraction electrode is used to extract the incident electron beam into the lens barrel; The condenser is used to converge the incident electron beam; The scanning coil is used to deflect the incident electron beam to scan the sample to be tested and generate the secondary electrons; The objective lens is used to receive and focus the secondary electrons.

3. The secondary electron detection system in the scanning electron microscope barrel according to claim 2, characterized in that: The electrode cover is semi-enclosed and is disposed on the secondary electron detector.

4. The secondary electron detection system in the scanning electron microscope barrel according to claim 3, characterized in that: The electrode cover is located below the secondary electron detector and is provided with an electrode mesh.

5. The secondary electron detection system in the scanning electron microscope barrel according to claim 2, characterized in that: A deceleration pole is also provided between the objective lens and the sample, and the deceleration pole is at the same pressure as the sample.

6. The secondary electron detection system in the scanning electron microscope barrel according to claim 2 or 5, characterized in that: The secondary electron detector is also connected to an imaging system. The secondary electron detector receives the secondary electrons to detect the sample to be tested, and forms a detection signal to be sent to the imaging system for imaging.

Images