Coil driving system and scanning electron microscope

Abstract

The embodiment of the utility model discloses a coil driving system and a scanning electron microscope, and the coil driving system suitable for the scanning electron microscope comprises a power module, a voltage regulation module, a constant current driving module and a coil module. Wherein the input end and the output end of the constant-current driving module are connected with the voltage adjusting module and the coil module respectively, the voltage adjusting module can adjust the voltage of the input end of the constant-current driving module according to the working current of the coil module, and therefore the dissipation power of the constant-current driving module is adjusted. When the working current of the coil module is small, the voltage adjusting module can adjust the dissipation power of the constant-current driving module to be low, and the size of the scanning electron microscope can be reduced.

Description

Technical Field

[0001] This utility model relates to the field of scanning electron microscopy, and more particularly to a coil drive system for a scanning electron microscope. Background Technology

[0002] Electron microscopes, represented by transmission electron microscopes and scanning electron microscopes, are important tools for humankind to explore the microscopic world. They are widely used in many fields such as materials science, life sciences, semiconductor industry, geology, energy, medicine, and pharmaceuticals, playing a significant role in human scientific research and industrial production.

[0003] Miniaturization has become a trend in scanning electron microscopes (SEMs). However, this miniaturization process presents higher energy consumption requirements for the coil drive system. Currently, most SEM coil drive systems on the market use transistor push-pull drive circuits powered by a constant voltage power supply. When the coil operates at a lower current, the constant current drive module of the coil drive system will withstand a higher voltage, generating greater power dissipation. Larger heat dissipation devices must be used for cooling, making it difficult to reduce the size of the SEM.

[0004] Therefore, those skilled in the art are dedicated to developing a low-energy-consumption coil drive system to overcome the shortcomings of the prior art. Utility Model Content

[0005] Based on the above analysis, the present invention aims to provide a coil drive system for a scanning electron microscope. By setting a voltage regulation module, the power dissipation of the coil drive system is reduced, the heat sink volume is reduced, and thus the size of the scanning electron microscope is reduced.

[0006] To achieve the above objectives, this disclosure provides the following technical solution:

[0007] In a first aspect, a coil driving system suitable for scanning electron microscopes is provided, comprising: a power supply module, a coil module, a constant current driving module, and a voltage regulation module. The input and output terminals of the constant current driving module are respectively connected to the voltage regulation module and the coil module. The voltage regulation module can adjust the input voltage of the constant current driving module according to the operating information of the coil module, thereby adjusting the power dissipation of the constant current driving module.

[0008] In a second aspect, a scanning electron microscope is provided, which includes the aforementioned coil drive system.

[0009] The technical solutions of this disclosure will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0010] The accompanying drawings, which form part of this specification, illustrate embodiments of this disclosure and, together with the description, serve to explain the principles of this disclosure.

[0011] This disclosure will become clearer with reference to the accompanying drawings and the following detailed description, wherein:

[0012] Figure 1 This utility model provides a schematic diagram of the structure of a coil drive system.

[0013] In the diagram, 1 is the power supply module; 2 is the voltage regulation module; 3 is the constant current drive module; 4 is the coil module; 21 is the control unit; 22 is the execution unit; 221 is the MOSFET; 222 is the filter component; 23 is the information processing unit; and 24 is the sampling component.

[0014] It should be noted that these accompanying drawings and textual descriptions are not intended to limit the scope of the present invention in any way, but rather to illustrate the concept of the present invention to those skilled in the art by referring to specific embodiments. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate this utility model, but are not intended to limit the scope of this utility model.

[0016] Scanning electron microscopy (SEM) is a microscopy technique that uses a finely focused electron beam to scan the surface of a sample, modulating the resulting physical signals to create an image. Driven by a coil drive system, the electron beam performs a grid-like scan of the sample surface in a specific temporal and spatial sequence. When the focused electron beam interacts with the sample, secondary electron emission occurs. The detector collects these secondary electron signals and converts them into electrical signals, which are then amplified and input to the display tube to form a secondary electron image.

[0017] Some embodiments of this disclosure provide a coil driving system. For example... Figure 1 As shown, the coil drive system includes a power supply module 1, a voltage regulation module 2, a constant current drive module 3, and a coil module 4. The power supply module 1 provides power to the coil drive system; the coil module 4 generates a magnetic field; the input and output terminals of the constant current drive module 3 are connected to the voltage regulation module 2 and the coil module 4, respectively. The voltage regulation module 2 is configured to adjust the input voltage of the constant current drive module 3 based on the operating information of the coil module 4, thus regulating the input voltage of the constant current drive module 3.

[0018] In some alternative implementations, the operating information of the coil module 4 may include operating current or operating voltage, which reflects the magnitude of the operating current of the coil module 4.

[0019] In some alternative implementations, when the operating current of the coil module 4 is small, the voltage regulation module 2 is configured to reduce the input voltage of the constant current drive module 3, thereby reducing the power dissipation of the constant current drive module 3, which is beneficial to the reduction of the size of the electron scanning microscope; when the operating current of the coil module 4 is large, the voltage regulation module 2 is configured to increase the input voltage of the constant current drive module 3 to ensure the stability of the current in the coil drive system.

[0020] In some alternative implementations, the power supply module 1 may be a constant voltage power supply, which may be set to 48V, 24V, or 12V, and may be powered by an AC / DC converter.

[0021] In some optional embodiments, the constant current drive module 3 may include a current control module with closed-loop feedback regulation to improve the stability of the drive current and enhance the clarity of the electron scanning image. In some optional embodiments, the coil module 4 may include a magnetic lens coil, under the drive of the magnetic lens coil, the electron beam performs a grid scan on the sample surface in a specific time and spatial sequence.

[0022] In some alternative embodiments, the voltage regulation module 2 may include an output regulation component and a sampling component 24. The output regulation component is connected to the output terminal of the power supply module 1 and the input terminal of the constant current drive module 3, respectively; the sampling component 24 is used to acquire the operating information of the coil module 4; the output regulation component is also connected to the sampling component 24, such that the output regulation component is configured to adjust the voltage at the input terminal of the constant current drive module 3 according to the operating information of the coil module 4.

[0023] In some alternative implementations, the sampling component 24 may include a sampling resistor, one end of which may be connected to the coil module 4 and the other end grounded. The output adjustment component can obtain the current flowing through the sampling resistor by detecting the voltage across the sampling resistor, and thus obtain the operating information of the coil module 4.

[0024] In some alternative embodiments, the output adjustment component may include an information processing unit 23, a control unit 21, and an execution unit 22. The information processing unit 23 processes the working information and feeds the result back to the control unit 21. The control unit 21 controls the execution unit 22 to adjust the voltage at the input terminal of the constant current drive module 3 according to the result.

[0025] In some optional embodiments, the information processing unit 23 includes a comparison amplification module, which is used to compare the reference working information and the working information under the working state of the sampling component 24, and feed the result back to the control unit 21 to realize the in-phase amplification and comparison function of the feedback signal of the sampling component 24.

[0026] In some alternative examples, the comparison amplification module includes a voltage amplifier and a voltage error amplifier, with one end of the voltage error amplifier connected to the control unit 21 and the other end connected to the voltage amplifier, the other end of which is used to connect to the sampling component 24.

[0027] In some alternative examples, the voltage amplifier may include a first amplification module and a second amplification module connected in parallel. When the operating current of the coil module 4 is at its maximum value, the first amplification module provides an amplified voltage signal, making the voltage at the input terminal of the constant current drive module 3 sufficiently high. When the operating current of the coil module 4 is at its minimum value, the second amplification module provides an amplified voltage signal, making the voltage at the input terminal of the constant current drive module 3 sufficiently low. This satisfies the voltage regulation requirements of the coil drive system across the entire operating current range, such as a variable voltage drive within the operating current range of +5 to +32V.

[0028] In some optional examples, the voltage error amplifier performs proportional integration adjustment based on the differential-mode voltage of the coil drive circuit and the feedback signal from the voltage regulator of the first or second amplification module, and inputs the result to the control unit 21. In some optional examples, the control unit 21 may include a UC3849 chip, which includes a PWM generation pin and a PWM adjustment pin. The PWM generation pin is used to output a PWM wave to the execution unit 22 to adjust the output voltage value. The PWM adjustment pin is connected to the voltage error amplifier to control the output voltage value.

[0029] In some optional examples, the execution unit 22 includes a MOSFET 221 metal-oxide-semiconductor field-effect transistor, which includes a gate, a drain, and a drain. The control unit 21 outputs a PWM wave based on the result, and controls the MOSFET 221 to turn on and off according to the magnitude of the PWM wave, so as to adjust the voltage at the input terminal of the constant current drive module 3.

[0030] In some optional examples, the execution unit 22 further includes a filter component 222, which is connected to the output of the MOSFET 221 and is used to modulate the voltage waveform at the input of the constant current drive module 3, thereby reducing the noise of the drive input voltage and reducing the output ripple during the operation of the DC-DC converter. The filter component 222 may include components such as inductors, resistors, and capacitors.

[0031] In some alternative embodiments, the coil drive system further includes a drive board, wherein at least one of the voltage regulation module 2 and the constant current drive module 3 is disposed on the drive board, which is beneficial to the integration of the coil drive circuit, facilitates the installation of the coil drive system, and also facilitates the overall heat dissipation of the coil drive system and reduces the thermal noise of the drive board.

[0032] In some optional examples, the driver board can integrate a combination of one or more voltage regulation modules 2 and constant current drive modules 3 to drive multiple coil modules 4, precisely adjusting the power supply for each coil module 4 to further reduce energy consumption. Alternatively, the coil driver board can also be equipped with only one voltage regulation module 2 and multiple constant current drive modules 3, using one voltage regulation module 2 to simultaneously adjust the voltage input values ​​of multiple coil modules 4, thereby further improving integration.

[0033] In some optional examples, the driver board also integrates a temperature detection unit and an alarm unit. When the temperature detection unit detects that the temperature of a component in the coil drive system or the driver board exceeds a certain temperature, it sends an alarm signal to the alarm unit. The alarm unit then issues a reminder to the user based on the alarm signal, which may include light, sound, or on-screen display.

[0034] In some alternative embodiments, the coil drive system may further include a voltage protection circuit, which is connected to the output terminal of the power module 1 or the coil module 4, and outputs a protection signal as an output feedback signal to the power module 1.

[0035] In some alternative examples, the coil drive system may also include a heat dissipation component, which may be mounted on the coil module 4 or the constant current drive module 3, or on the drive board. The heat dissipation component may include heat sinks and heat plates.

[0036] In some alternative implementations, the coil drive system includes a constant voltage power supply with a relatively high safety supply voltage, such as 48V, to power the coil drive board. This voltage should meet the power supply requirements of multiple coils under maximum current demand. This constant voltage power supply can be powered by an AC / DC converter, which typically has a high conversion efficiency, usually above 90%, and a converter power of 400W or more, meeting the power supply requirements of the coil drive system while generating relatively little heat.

[0037] The driver board is equipped with a voltage regulation module 2 that can adjust the output according to the change of current and a constant current drive module 3. The input voltage of the constant current drive module 3 is set by the voltage regulation module 2 on the driver board based on the operating current feedback of the coil module 4. The operating current of the coil module 4 is collected by the sampling component 24 of the voltage output module 2.

[0038] When the coil module 4 operates at a lower current, the voltage regulation module 2 adjusts to provide a lower input voltage to the constant current drive module 3, significantly reducing the power dissipation of the drive board. When the coil module 4 operates at a higher current, the voltage regulation module 2 adjusts to provide a higher supply voltage, providing sufficient voltage to the constant current drive module 3 and ensuring its operating current.

[0039] Some embodiments of this disclosure provide a scanning electron microscope, which may include the aforementioned coil drive system, electromagnetic lens system, electron gun and sample chamber, etc. By setting the aforementioned coil drive system, the heat sink volume can be reduced, thereby reducing the overall volume of the scanning electron microscope, reducing power consumption and improving image quality.

[0040] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this disclosure to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, adjustments, additions, and sub-combinations thereof.

Claims

1. A coil driving system, characterized in that, include: A power supply module (1) is used to provide power to the coil drive system; Coil module (4) is used to generate a magnetic field; A constant current drive module (3) is provided, the output of which is connected to the coil module (4) and is used to adjust the drive current of the coil module (4). The voltage regulation module (2) includes an output regulation component and a sampling component (24); the sampling component (24) is connected to one end of the coil module (4) and is used to collect the working information of the coil module (4); the output regulation component is connected to the output end of the power supply module (1) and the input end of the constant current drive module (3) respectively, and the output regulation component is configured to adjust the voltage of the input end of the constant current drive module (3) according to the working information.

2. The coil drive system according to claim 1, wherein, The sampling component (24) includes a sampling resistor, one end of which is connected to the coil module (4) and the other end is grounded.

3. The coil drive system according to claim 2, wherein, The operating information is the voltage or current across the sampling resistor.

4. The coil drive system according to claim 1, wherein, The output adjustment component includes an information processing unit (23), a control unit (21), and an execution unit (22). The information processing unit (23) processes the working information and feeds the result back to the control unit (21). The control unit (21) controls the execution unit (22) to adjust the voltage at the input terminal of the constant current drive module (3) according to the result.

5. The coil drive system according to claim 4, wherein, The information processing unit (23) includes a comparison amplification module, which is used to compare the reference working information and the working information under the working state of the sampling component (24) and feed the result back to the control unit (21).

6. The coil drive system according to claim 5, wherein, The comparison amplification module includes a voltage amplifier and a voltage error amplifier. One end of the voltage error amplifier is connected to the control unit (21), and the other end is connected to the voltage amplifier. The other end of the voltage amplifier is used to connect to the sampling component (24).

7. The coil drive system according to claim 4, wherein, The execution unit (22) includes a MOSFET (221). The control unit (21) outputs a PWM wave according to the result and uses the PWM wave to control the MOSFET (221) to adjust the voltage at the input terminal of the constant current drive module (3).

8. The coil drive system according to claim 7, wherein, The execution unit (22) further includes a filter component (222), which is connected to the output terminal of the MOSFET (221) and is used to modulate the voltage waveform at the input terminal of the constant current drive module (3).

9. The coil drive system according to any one of claims 1-8 further includes a heat dissipation component, the heat dissipation component being installed on the coil module (4) or the constant current drive module (3).

10. A scanning electron microscope comprising the coil drive system according to any one of claims 1-9.

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