Magnification adjustment circuit, method and scanning electron microscope for a scanning electron microscope

Abstract

The application relates to the technical field of electronic circuits, and discloses a magnification adjusting circuit, a method and a scanning electron microscope for the scanning electron microscope. The magnification adjusting circuit comprises a control circuit, an X scanning gear shifting circuit, an X scanning feedback circuit, a Y scanning gear shifting circuit and a Y scanning feedback circuit. The control circuit is connected with an upper computer, the X scanning feedback circuit, the Y scanning feedback circuit, the X scanning gear shifting circuit and the Y scanning gear shifting circuit respectively. The X scanning gear shifting circuit is further connected with the X scanning feedback circuit. The Y scanning gear shifting circuit is further connected with the Y scanning feedback circuit. The circuit can realize a total of 12 magnification gears, and the adjustment interval between two gears is 4 times, so that the magnification calibration accuracy of the scanning electron microscope is greatly improved. The circuit is feedback regulation in the whole adjustment range, the control accuracy is high, and the circuit is not affected by load changes.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electronic circuit, in particular to a magnification adjusting circuit, method and scanning electron microscope for scanning electron microscope. BACKGROUND

[0002] The scanning electron microscope is an electron-optical instrument for observing microstructure. The focused electron beam is used to scan the sample surface line by line, and the secondary electrons or backscattered electrons are generated on the sample surface by the electron beam bombardment. The efficiency of the generation is related to the sample surface topography or material. The secondary electrons or backscattered electrons generated on the sample surface are collected, and the position of the electron beam scanning on the sample surface and the number of the generated secondary electrons or backscattered electrons are represented in the form of two-dimensional image, that is, the secondary electron image or backscattered electron image of the scanning electron microscope is obtained. The resolution of the scanning electron microscope image can reach nanometer level or even better than 1.0 nanometer, and plays an irreplaceable role in the fields of new materials, new energy, national defense and scientific research.

[0003] During the operation of the scanning electron microscope, the magnification is changed according to different observation samples or different needs. The magnification of the scanning electron microscope is determined by the deflection range of the electron beam and the size of the image display. In the case of the determined size of the image display, the deflection range of the electron beam directly determines the magnification of the scanning electron microscope. The deflection range of the electron beam is determined by the size of the deflection magnetic field, and the deflection magnetic field is determined by the structure of the scanning coil, the number of turns and the supply current. In the actual operation process, the supply current of the deflection coil is changed to control the magnification of the scanning electron microscope. The magnification of the scanning electron microscope is generally several times to several hundred thousand times, with large span and high precision requirement.

[0004] Generally, 4-6 positions are set for the magnification of the commonly used scanning electron microscope, and the magnification of the scanning electron microscope is not high and the linearity is poor due to the influence of the thermal drift or linearity of the electronic components. SUMMARY

[0005] Therefore, the present application provides a magnification adjusting circuit, method and scanning electron microscope for scanning electron microscope to solve the problem of low magnification precision and poor linearity of the scanning electron microscope.

[0006] In a first aspect, the present application provides a magnification adjusting circuit for scanning electron microscope, which comprises a control circuit, an X scanning gear shifting circuit, an X scanning feedback circuit, a Y scanning gear shifting circuit and a Y scanning feedback circuit, wherein,

[0007] The control circuit is connected with the upper computer, the X scan feedback circuit, the Y scan feedback circuit, the X scan gear shifting circuit and the Y scan gear shifting circuit respectively, the X scan gear shifting circuit is further connected with the X scan feedback circuit, and the Y scan gear shifting circuit is further connected with the Y scan feedback circuit;

[0008] The control circuit switches the amplification mode and amplification gear of the X scan gear shifting circuit according to the X scan control signal sent by the upper computer, adjusts the gear current of the X scan gear shifting circuit according to the deviation between the voltage signal fed back by the X scan feedback circuit and the X scan control signal, and the amplification mode includes three kinds, each amplification mode includes four amplification gears.

[0009] The control circuit switches the amplification mode and amplification gear of the Y scan gear shifting circuit according to the Y scan control signal sent by the upper computer, adjusts the gear current of the Y scan gear shifting circuit according to the deviation between the voltage signal fed back by the Y scan feedback circuit and the Y scan control signal, and the amplification mode includes three kinds, each amplification mode includes four amplification gears.

[0010] The amplification multiple adjusting circuit for the scanning electron microscope provided by the application is divided into three amplification modes, each amplification mode is divided into four amplification gears, so that the circuit can realize a total of 12 amplification gears, the adjustment interval between two gears is 4 times, the calibration precision of the amplification multiple of the scanning electron microscope is greatly improved, and the circuit is feedback regulated in the whole adjustment range, the control precision is high, and is not affected by load changes.

[0011] In an optional embodiment, the X scan gear shifting circuit and the Y scan gear shifting circuit each include a mode switching circuit and a gear switching circuit, wherein,

[0012] The mode switching circuit is connected with the gear switching circuit, and the mode switching circuit and the gear switching circuit are connected with the output end of the control circuit;

[0013] The mode switching circuit is used for switching the amplification mode of the X scan gear shifting circuit and the Y scan gear shifting circuit, and the gear switching circuit is used for gear switching in each amplification mode.

[0014] In an optional embodiment, the gear switching circuit includes a first switch, a second switch, a third switch, a fourth switch, a first resistor, a second resistor, a third resistor and a fourth resistor, wherein,

[0015] One end of the first switch is connected with one end of the second switch, one end of the third switch, one end of the fourth switch and the mode switching circuit respectively, the other end of the first switch is connected with one end of the first resistor and one end of the second resistor respectively, the other end of the first resistor is grounded;

[0016] The other end of the second switch is connected with the other end of the second resistor and one end of the third resistor respectively, the other end of the third switch is connected with the other end of the third resistor and one end of the fourth resistor respectively, the other end of the fourth switch is connected with the other end of the fourth resistor and the output end of the X / Y scan feedback circuit.

[0017] In an alternative embodiment, the gear switching circuit further comprises a fifth switch, a sixth switch, a seventh switch, an eighth switch, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor, a fourteenth resistor, a fifteenth resistor, a sixteenth resistor, a seventeenth resistor and an eighteenth resistor, wherein,

[0018] One end of the fifth switch is connected with one end of the sixth switch, one end of the seventh switch, one end of the eighth switch and the mode switching circuit respectively, the other end of the fifth switch is connected with one end of the fifth resistor, one end of the sixth resistor and one end of the scan coil resistor respectively, the other end of the fifth resistor is connected with one end of the seventh resistor and one end of the eighth resistor respectively;

[0019] The other end of the sixth switch is connected with the other end of the seventh resistor, one end of the ninth resistor and one end of the tenth resistor respectively, the other end of the ninth resistor is connected with one end of the eleventh resistor and one end of the twelfth resistor respectively;

[0020] The other end of the seventh switch is connected with the other end of the eleventh resistor, one end of the thirteenth resistor and one end of the fourteenth resistor respectively, the other end of the thirteenth resistor is connected with one end of the fifteenth resistor and one end of the sixteenth resistor respectively;

[0021] The other end of the eighth switch is connected with the other end of the fifteenth resistor, one end of the seventeenth resistor and one end of the eighteenth resistor respectively, the other end of the seventeenth resistor is connected with the other end of the eighteenth resistor, the other end of the sixteenth resistor, the other end of the fourteenth resistor, the other end of the twelfth resistor, the other end of the tenth resistor, the other end of the eighth resistor, the other end of the sixth resistor, the other end of the scan coil resistor and the mode switching circuit respectively.

[0022] In an alternative embodiment, the mode switching circuit comprises a ninth switch, a tenth switch, an eleventh switch, a twelfth switch, a thirteenth switch and a fourteenth switch, wherein,

[0023] One end of the ninth switch is connected to one end of the tenth switch and one end of the eleventh switch respectively, the other end of the ninth switch is connected to the other end of the fifth switch, one end of the fifth resistor, one end of the sixth resistor and one end of the scanning coil resistor respectively, the other end of the tenth switch is connected to one end of the fifth switch, one end of the sixth switch, one end of the seventh switch and one end of the eighth switch respectively, the other end of the eleventh switch is connected to the output end of the X / Y scanning feedback circuit;

[0024] One end of the twelfth switch is connected to one end of the thirteenth switch, one end of the fourteenth switch and the other end of the scanning coil resistor respectively, the other end of the twelfth switch is connected to one end of the first switch, one end of the second switch, one end of the third switch and one end of the fourth switch respectively, the other end of the thirteenth switch is connected to the other end of the fourth switch, the other end of the fourth resistor and the output end of the X / Y scanning feedback circuit respectively, the other end of the fourteenth switch is grounded.

[0025] In an alternative embodiment, the X scanning gear shifting circuit and the Y scanning gear shifting circuit further comprise a first compensation circuit and a second compensation circuit, wherein,

[0026] One end of the first compensation circuit is connected to the other end of the fifth switch, one end of the fifth resistor and one end of the sixth resistor respectively, the other end of the first compensation circuit is connected to the other end of the ninth switch and one end of the scanning coil resistor respectively;

[0027] One end of the second compensation circuit is connected to the other end of the sixth resistor and one end of the thirteenth switch respectively, the other end of the second compensation circuit is connected to the other end of the scanning coil resistor and one end of the twelfth switch respectively.

[0028] In an alternative embodiment, the control circuit comprises an MCU, an X control unit, an X power amplification unit, a Y control unit and a Y power amplification unit, wherein,

[0029] The input end of the MCU is connected to the upper computer, the output end of the MCU is connected to the input end of the X control unit, the input end of the Y control unit, the X scanning gear shifting circuit and the Y scanning gear shifting circuit respectively;

[0030] The input end of the X control unit is further connected with the X scan feedback circuit, the output end of the X control unit is connected with the input end of the X power amplification unit, the output end of the X power amplification unit is connected with the X scan gear shifting circuit, the input end of the Y control unit is further connected with the Y scan feedback circuit, the output end of the Y control unit is connected with the input end of the Y power amplification unit, and the output end of the Y power amplification unit is connected with the Y scan gear shifting circuit.

[0031] In a second aspect, the present application provides a magnification adjustment method for a scanning electron microscope, based on the magnification adjustment circuit for a scanning electron microscope in the first aspect or any of the corresponding embodiments thereof, the method comprising:

[0032] The amplification mode and amplification gear of the X scan gear shifting circuit are switched according to the X scan control signal sent by the upper computer, and the amplification mode and amplification gear of the Y scan gear shifting circuit are switched according to the Y scan control signal sent by the upper computer, wherein the amplification mode includes three kinds, and each amplification mode includes four amplification gears;

[0033] The gear current of the X scan gear shifting circuit is adjusted according to the deviation between the voltage signal fed back by the X scan feedback circuit and the X scan control signal, and the gear current of the Y scan gear shifting circuit is adjusted according to the deviation between the voltage signal fed back by the Y scan feedback circuit and the Y scan control signal.

[0034] The magnification adjustment method for a scanning electron microscope provided by the present application divides the magnification adjustment circuit into three amplification modes, each amplification mode is divided into four amplification gears, a total of 12 amplification gears can be realized, the adjustment interval between two gears is 4 times, the calibration accuracy of the magnification of the scanning electron microscope is greatly improved, and the circuit is feedback regulated in the whole adjustment range, has high control accuracy, and is not affected by load changes.

[0035] In a third aspect, the present application provides a scanning electron microscope comprising the magnification adjustment circuit for a scanning electron microscope in the first aspect or any of the corresponding embodiments thereof.

[0036] The scanning electron microscope provided by the present application has greatly improved calibration accuracy of the magnification of the scanning electron microscope by using the magnification adjustment circuit for a scanning electron microscope. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the drawings needed in the specific embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0038] Figure 1 is a principle block diagram of a magnification adjustment circuit for a scanning electron microscope according to an embodiment of the present application;

[0039] Figure 2 is a schematic diagram of a magnification adjustment circuit for a scanning electron microscope according to an embodiment of the present application;

[0040] Figure 3 is an equivalent circuit diagram of a magnification adjustment circuit for a scanning electron microscope according to an embodiment of the present application;

[0041] Figure 4 is a further equivalent circuit diagram of a magnification adjustment circuit for a scanning electron microscope according to an embodiment of the present application;

[0042] Figure 5 is a further equivalent circuit diagram of a magnification adjustment circuit for a scanning electron microscope according to an embodiment of the present application;

[0043] Figure 6 is a principle block diagram of a control circuit according to an embodiment of the present application;

[0044] Figure 7 is a partial circuit diagram of a control circuit according to an embodiment of the present application;

[0045] Figure 8 is a flowchart of a magnification adjustment method for a scanning electron microscope according to an embodiment of the present application. DETAILED DESCRIPTION

[0046] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts should fall into the scope of the present application.

[0047] In the description of the present application, it should be noted that the terms “center”, “upper”, “lower”, “left”, “right”, “vertical”, “horizontal”, “inner”, “outer” and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms “first”, “second”, “third” are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0048] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "linking" should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integral connection, it can be mechanical connection, or electrical connection, it can be direct connection, or indirect connection through intermediate medium, or internal connection of two elements, it can be wireless connection, or wired connection. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0049] In addition, the technical features involved in the different embodiments of the application described below can be combined with each other as long as there is no conflict between them.

[0050] The present application provides a magnification adjusting circuit for scanning electron microscope, as shown in the figure, comprising: a control circuit, an X scanning gear circuit, an X scanning feedback circuit, a Y scanning gear circuit and a Y scanning feedback circuit. Wherein, the control circuit is connected with the upper computer, the X scanning feedback circuit, the Y scanning feedback circuit, the X scanning gear circuit and the Y scanning gear circuit respectively, the X scanning gear circuit is further connected with the X scanning feedback circuit, and the Y scanning gear circuit is further connected with the Y scanning feedback circuit. Figure 1

[0051] Specifically, the control circuit switches the amplification mode and amplification gear of the X scanning gear circuit according to the X scanning control signal sent by the upper computer, and adjusts the gear current of the X scanning gear circuit according to the deviation between the voltage signal fed back by the X scanning feedback circuit and the X scanning control signal, the amplification mode includes three kinds, and each amplification mode includes four amplification gears. The control circuit switches the amplification mode and amplification gear of the Y scanning gear circuit according to the Y scanning control signal sent by the upper computer, and adjusts the gear current of the Y scanning gear circuit according to the deviation between the voltage signal fed back by the Y scanning feedback circuit and the Y scanning control signal, the amplification mode includes three kinds, and each amplification mode includes four amplification gears.

[0052] In the embodiment of the present application, the actual parameter of scanning electron microscope magnification control is scanning coil current, which is generally within ±3A. In order to control the heat quantity of scanning coil, the resistance of scanning coil is generally small, only several tenths to several ohms. The smaller the scanning current is, the higher the magnification is. In order to improve the control precision of magnification, several gears such as ampere level, milliampere level and microampere level are generally set. Too few gears will reduce the control precision by relying on data fitting, and too many gears will greatly increase the circuit structure and the workload of magnification calibration. Therefore, the embodiment designs a magnification adjusting circuit with a total of 12 gears, and the interval between two gears is 4 times.

[0053] ​The application provides a magnification adjusting circuit for a scanning electron microscope, which is divided into three magnification modes, and each magnification mode is divided into four magnification gears, so that the circuit can realize a total of 12 magnification gears, the adjustment interval between two gears is 4 times, and the calibration accuracy of the scanning electron microscope magnification is greatly improved.

[0054] In an optional embodiment, the X scanning gear switching circuit and the Y scanning gear switching circuit each include a mode switching circuit and a gear switching circuit.

[0055] Specifically, the X scanning gear switching circuit includes an X scanning mode switching circuit and an X scanning gear switching circuit. The X scanning mode switching circuit is used to switch the magnification mode of the X scanning gear switching circuit, and the Y scanning mode switching circuit is used to switch the magnification mode of the Y scanning gear switching circuit. The X scanning gear switching circuit is used to switch the gear in each magnification mode of the X scanning gear switching circuit, and the Y scanning gear switching circuit is used to switch the gear in each magnification mode of the Y scanning gear switching circuit.

[0056] Further, the magnification mode of the X scanning gear switching circuit is divided into Mode1, Mode2 and Mode3, and the scanning magnification from low to high uses Mode1, Mode2 and Mode3. Each magnification mode corresponds to Stage1, Stage2, Stage3 and Stage4. Similarly, the magnification mode of the Y scanning gear switching circuit is divided into Mode1, Mode2 and Mode3, and the scanning magnification from low to high uses Mode1, Mode2 and Mode3. Each magnification mode corresponds to Stage1, Stage2, Stage3 and Stage4, and the scanning magnification from low to high uses Stage1, Stage2, Stage3 and Stage4.

[0057] In an optional embodiment, the X scanning gear switching circuit is taken as an example for description. Figure 2As shown, the X-scan mode switching circuit includes: a first switch K14, a second switch K12, a third switch K11, a fourth switch K13, a first resistor R50, a second resistor R49, a third resistor R48, and a fourth resistor R47. One end of the first switch K14 is connected to one end of the second switch K12, one end of the third switch K11, one end of the fourth switch K13, and the X-scan mode switching circuit. The other end of the first switch K14 is connected to one end of the first resistor R50 and one end of the second resistor R49, and the other end of the first resistor R50 is grounded. The other end of the second switch K12 is connected to the other end of the second resistor R49 and one end of the third resistor R48. The other end of the third switch K11 is connected to the other end of the third resistor R48 and one end of the fourth resistor R47. The other end of the fourth switch K13 is connected to the other end of the fourth resistor R47 and the output terminal of the X-scan feedback circuit.

[0058] Specifically, switches K14, K12, K11, and K13 are the amplification level switching switches in Mode 1. When switch K14 is closed, the current for Stage 1 is I_1; when switch K12 is closed, the current for Stage 2 is I_2; when switch K11 is closed, the current for Stage 3 is I_3; and when switch K13 is closed, the current for Stage 4 is I_4. In this circuit mode, the resistance of R47 is 1 / 150 ohm, the resistance of R48 is 1 / 50 ohm, the resistance of R49 is 2 / 25 ohm, and the resistance of R48 is 8 / 25 ohm.

[0059] In one alternative implementation, such as Figure 2 As shown, the X-scan range switching circuit also includes: fifth switch K4, sixth switch K3, seventh switch K5, eighth switch K6, fifth resistor R24, sixth resistor R32, seventh resistor R23, eighth resistor R31, ninth resistor R22, tenth resistor R35, eleventh resistor R21, twelfth resistor R30, thirteenth resistor R20, fourteenth resistor R34, fifteenth resistor R19, sixteenth resistor R33, seventeenth resistor R28, and eighteenth resistor R29.

[0060] Specifically, one end of the fifth switch K4 is connected to one end of the sixth switch K3, one end of the seventh switch K5, one end of the eighth switch K6, and the mode switching circuit. The other end of the fifth switch K4 is connected to one end of the fifth resistor R24, one end of the sixth resistor R32, and one end of the scanning coil resistor CoilX. The other end of the fifth resistor R24 ​​is connected to one end of the seventh resistor R23 and one end of the eighth resistor R31. The other end of the sixth switch K3 is connected to one end of the seventh resistor R23, one end of the ninth resistor R22, and one end of the tenth resistor R35. The other end of the ninth resistor R22 is connected to one end of the eleventh resistor R21 and one end of the twelfth resistor R30. The other end of the seventh switch K5 is connected to one end of the eleventh resistor R21, one end of the thirteenth resistor R20, and one end of the fourteenth resistor R34. The other end of the thirteenth resistor R20 is connected to one end of the fifteenth resistor R19 and one end of the sixteenth resistor R33. The other end of the eighth switch K6 is connected to the other end of the fifteenth resistor R19, one end of the seventeenth resistor R28, and one end of the eighteenth resistor R29. The other end of the seventeenth resistor R28 is connected to the other end of the eighteenth resistor R29, the other end of the sixteenth resistor R33, the other end of the fourteenth resistor R34, the other end of the twelfth resistor R30, the other end of the tenth resistor R35, the other end of the eighth resistor R31, the other end of the sixth resistor R32, the other end of the scanning coil resistor CoilX, and the mode switching circuit.

[0061] Specifically, switches K4 (5th), K3 (6th), K5 (7th), and K6 (8th) are the amplification level switching switches for Mode 2 and Mode 3. In Mode 2, when switch K4 is closed, the current at Stage 1 is I_5; when switch K3 is closed, the current at Stage 2 is I_6; when switch K5 is closed, the current at Stage 3 is I_7; and when switch K6 is closed, the current at Stage 4 is I_4. In Mode 3, when switch K4 is closed, the current at Stage 1 is I_9; when switch K3 is closed, the current at Stage 2 is I_10; when switch K5 is closed, the current at Stage 3 is I_11; and when switch K6 is closed, the current at Stage 4 is I_12.

[0062] In one alternative implementation, such as Figure 2 As shown, the X-scan mode switching circuit includes: the ninth switch K1, the tenth switch K2, the eleventh switch K7, the twelfth switch K8, the thirteenth switch K9, and the fourteenth switch K10.

[0063] The other end of the ninth switch K1 is connected with the other end of the fifth switch K4, one end of the fifth resistor R24, one end of the sixth resistor R32 and one end of the scanning coil resistor CoilX respectively, the other end of the tenth switch K2 is connected with one end of the fifth switch K4, one end of the sixth switch K3, one end of the seventh switch K5 and one end of the eighth switch K6 respectively, the other end of the eleventh switch K7 is connected with the output end of the X scanning feedback circuit. One end of the twelfth switch K8 is connected with one end of the thirteenth switch K9, one end of the fourteenth switch K10 and the other end of the scanning coil resistor CoilX respectively, the other end of the twelfth switch K8 is connected with one end of the first switch K14, one end of the second switch K12, one end of the third switch K11 and one end of the fourth switch K13 respectively, the other end of the thirteenth switch K9 is connected with the other end of the fourth switch K13, the other end of the fourth resistor R47 and the output end of the X scanning feedback circuit respectively, the other end of the fourteenth switch K10 is grounded.

[0064] Specifically, the ninth switch K1 and the twelfth switch K8 are switches for controlling the Mode1 mode; the tenth switch K2 and the thirteenth switch K9 are switches for controlling the Mode2 mode; the eleventh switch K7 and the fourteenth switch K10 are switches for controlling the Mode3 mode.

[0065] When the ninth switch K1 and the twelfth switch K8 are closed, the X scanning gear circuit enters the Mode1 mode, and the equivalent circuit diagram of the X scanning gear circuit at this time is as shown in Figure 3 According to the equivalent circuit diagram as shown in Figure 3 It can be known that I_1 is the maximum current, I_2 is 1 / 4 of I_1, I_3 is 1 / 4 of I_2, and I_4 is 1 / 4 of I_3. Since the smaller the scanning current is, the higher the amplification is, therefore, when the fourth switch K13 corresponding to I_4 is closed, the scanning amplification of the Stage4 gear is the highest, and when the first switch K14 corresponding to I_1 is closed, the scanning amplification of the Stage1 gear is the lowest. The maximum voltage used by the circuit is I_1*(R100+ CoilX), therefore, the power supply is selected according to this standard, and the maximum feedback voltage is I_1*R50.

[0066] As shown in Figure 2As shown, when the tenth switch K2 and the thirteenth switch K9 are closed, the X scanning gear switching circuit enters Mode 2 mode, and by switching the gear switches K4, K3, K5 and K6 and cooperating with the T-shaped resistance network, the maximum current flowing through the scanning coil resistance CoilX decreases by 1 / 4. In this mode, I_5 is the maximum current, I_6 is 1 / 4 of I_5, I_7 is 1 / 4 of I_6, and I_8 is 1 / 4 of I_7. Since the smaller the scanning current is, the higher the amplification is. Therefore, when the eighth switch K6 corresponding to I_8 is closed, the scanning amplification of the Stage4 gear is the highest, and when the fifth switch K4 corresponding to I_5 is closed, the scanning amplification of the Stage1 gear is the lowest. At this time, the equivalent circuit diagram of the X scanning gear switching circuit is as shown in Figure 4 As shown in the equivalent circuit diagram as shown in Figure 4 As can be known from the equivalent circuit diagram as shown in Figure 4 In the equivalent circuit diagram, R* is the equivalent resistance of R45-R50.

[0067] As shown in the equivalent circuit diagram as shown in Figure 2 As shown, when the eleventh switch K7 and the fourteenth switch K10 are closed, the X scanning gear switching circuit enters Mode 3 mode, and by switching the gear switches K4, K3, K5 and K6 and cooperating with the T-shaped resistance network, the maximum current flowing through the scanning coil resistance CoilX decreases by 1 / 4. In this mode, I_9 is the maximum current, I_10 is 1 / 4 of I_9, I_11 is 1 / 4 of I_10, and I_12 is 1 / 4 of I_11. Since the smaller the scanning current is, the higher the amplification is. Therefore, when the eighth switch K6 corresponding to I_12 is closed, the scanning amplification of the Stage4 gear is the highest, and when the fifth switch K4 corresponding to I_9 is closed, the scanning amplification of the Stage1 gear is the lowest. At this time, the equivalent circuit diagram of the X scanning gear switching circuit is as shown in Figure 5 As shown in the equivalent circuit diagram as shown in Figure 5 As can be known from the equivalent circuit diagram as shown in

[0068] By adding the T-shaped resistance network in the Mode 2 mode and the Mode 3 mode, the control precision of the amplification adjustment circuit for the scanning electron microscope is improved.

[0069] In an alternative embodiment, asFigure 2 As shown, the X scan gear circuit further comprises a first compensation circuit and a second compensation circuit. One end of the first compensation circuit is connected with the other end of the fifth switch K4, one end of the fifth resistor R24 and one end of the sixth resistor R32 respectively, and the other end of the first compensation circuit is connected with the other end of the ninth switch K1 and one end of the scan coil resistor CoilX respectively. One end of the second compensation circuit is connected with the other end of the sixth resistor R32 and one end of the thirteenth switch K9 respectively, and the other end of the second compensation circuit is connected with the other end of the scan coil resistor CoilX and one end of the twelfth switch K8 respectively.

[0070] Specifically, in the actual use process, because of the existence of processing error, the scan coil resistor CoilX will have a certain error, which can be adjusted by R17, R25, R38 and R41 to make the sum of the four resistors and the scan coil resistance equal to R.

[0071] In an alternative embodiment, as shown in Figure 6 As shown, the control circuit comprises an MCU, an X control unit, an X power amplification unit, a Y control unit and a Y power amplification unit. The input end of the MCU is connected with the upper computer, the output end of the MCU is connected with the input end of the X control unit, the input end of the Y control unit, the X scan gear circuit and the Y scan gear circuit respectively, the input end of the X control unit is further connected with the X scan feedback circuit, the input end of the Y control unit is further connected with the Y scan feedback circuit, the output end of the X control unit is connected with the input end of the X power amplification unit, the output end of the X power amplification unit is connected with the X scan gear circuit, the output end of the Y control unit is connected with the input end of the Y power amplification unit, and the output end of the Y power amplification unit is connected with the Y scan gear circuit.

[0072] Specifically, the MCU receives the control command sent by the upper computer, and switches the amplification mode and amplification gear of the X / Y scan gear circuit according to the control signal, and sends the control signal to the X / Y control unit. The X scan feedback circuit also sends the collected feedback voltage to the X control unit, and in the X control unit, the gear current of the X scan gear circuit is adjusted according to the deviation of the feedback voltage signal and the control signal. The X power amplification unit delivers the adjusted gear current to the X scan gear circuit. The Y scan feedback circuit also sends the collected feedback voltage to the Y control unit, and in the Y control unit, the gear current of the Y scan gear circuit is adjusted according to the deviation of the feedback voltage signal and the control signal. The Y power amplification unit delivers the adjusted gear current to the Y scan gear circuit. Wherein, part of the circuit structure in the control circuit is shown in Figure 7 Wherein, U2A is the X control unit, and U1 is the X power amplification unit. The Y control unit and the Y power amplification unit are the same as Figure 7 Not shown again.

[0073] This invention provides a method for adjusting the magnification of a scanning electron microscope, based on the magnification adjustment circuit for a scanning electron microscope described in the above embodiments, such as... Figure 8 As shown, the method for adjusting the magnification of a scanning electron microscope includes the following steps:

[0074] Step S11: Switch the amplification mode and amplification level of the X-scan cutting circuit according to the X-scan control signal sent by the host computer, and switch the amplification mode and amplification level of the Y-scan cutting circuit according to the Y-scan control signal sent by the host computer. There are 3 amplification modes, and each amplification mode includes 4 amplification levels.

[0075] Specifically, the ninth switch K1 and the twelfth switch K8 are switches that control Mode 1; the tenth switch K2 and the thirteenth switch K9 are switches that control Mode 2; and the eleventh switch K7 and the fourteenth switch K10 are switches that control Mode 3.

[0076] When the ninth switch K1 and the twelfth switch K8 are closed according to the control signal, the X-scan switching circuit enters Mode 1 mode. The equivalent circuit diagram of the X-scan switching circuit at this time is as follows. Figure 3 As shown. According to... Figure 3 As shown in the equivalent circuit diagram, I_1 is the maximum current, I_2 is 1 / 4 of I_1, I_3 is 1 / 4 of I_2, and I_4 is 1 / 4 of I_3. Since a smaller scanning current results in a higher amplification factor, when the fourth switch K13 (corresponding to I_4) is closed, the Stage 4 scanning factor is the highest, and when the first switch K14 (corresponding to I_1) is closed, the Stage 1 scanning factor is the lowest. The maximum voltage used in this circuit is I_1 * (R100 + CoilX), therefore the power supply is selected based on this standard, and the maximum feedback voltage is I_1 * R50.

[0077] like Figure 2 As shown, when the tenth switch K2 and the thirteenth switch K9 are closed according to the control signal, the X-scan switching circuit enters Mode 2. By switching the switches K4, K3, K5, and K6, and in conjunction with the T-shaped resistor network, the maximum current flowing through the scanning coil resistor CoilX decreases by a factor of 1 / 4. In this mode, I_5 is the maximum current, I_6 is 1 / 4 of I_5, I_7 is 1 / 4 of I_6, and I_8 is 1 / 4 of I_7. Since a smaller scanning current results in a higher amplification factor, when the eighth switch K6 (corresponding to I_8) is closed, the Stage 4 scanning factor is the highest, and when the fifth switch K4 (corresponding to I_5) is closed, the Stage 1 scanning factor is the lowest. The equivalent circuit diagram of the X-scan switching circuit at this time is shown below. Figure 4 As shown. According to... Figure 4The equivalent circuit diagram shows that the current flowing through the feedback resistor is 3*I_5, which can be adjusted by adjusting the parallel value of R45 and R46 so that I_5 is 1 / 4 of I_4. Because the maximum feedback voltage is constant (I_1*R50), the parallel resistance value of R45 and R46 can be calculated accordingly, and the actual value of R45 and R46 can be adjusted accordingly. Figure 4 R* is the equivalent resistance of R45-R50.

[0078] As shown in Figure 2 When the eleventh switch K7 and the fourteenth switch K10 are closed according to the control signal, the X scan gear shifting circuit enters Mode 3 mode, and the maximum current flowing through the scan coil resistor CoilX decreases by 1 / 4 by switching the gear switches K4, K3, K5, and K6 and cooperating with the T-shaped resistor network. In this mode, I_9 is the maximum current, I_10 is 1 / 4 of I_9, I_11 is 1 / 4 of I_10, and I_12 is 1 / 4 of I_11. Since the smaller the scan current is, the higher the amplification factor is. Therefore, when the eighth switch K6 corresponding to I_12 is closed, the scan amplification factor of Stage4 gear is the highest, and when the fifth switch K4 corresponding to I_9 is closed, the scan amplification factor of Stage1 gear is the lowest. The equivalent circuit diagram of the X scan gear shifting circuit at this time is shown in Figure 5 According to the equivalent circuit diagram shown in Figure 5 According to the equivalent circuit diagram shown in

[0079] Step S12, adjusting the gear current of the X scan gear shifting circuit according to the deviation between the voltage signal fed back by the X scan feedback circuit and the X scan control signal, and adjusting the gear current of the Y scan gear shifting circuit according to the deviation between the voltage signal fed back by the Y scan feedback circuit and the Y scan control signal.

[0080] Specifically, the X / Y control unit receives the voltage signal fed back by the X / Y scan feedback circuit and the control signal of the MCU. In the X / Y control unit, the gear current of the X / Y scan gear shifting circuit is adjusted according to the deviation between the fed back voltage signal and the control signal. The X / Y power amplification unit delivers the adjusted gear current to the X / Y scan gear shifting circuit for feedback adjustment within the full range.

[0081] The further function description of the above method is the same as the corresponding embodiment described above, which will not be repeated here.

[0082] The application provides a magnification adjusting method for a scanning electron microscope, which divides a magnification adjusting circuit into three magnification modes, each of which is divided into four magnification gears, so that a total of 12 magnification gears are realized, the interval between two gears is 4 times, and the calibration precision of the scanning electron microscope is greatly improved. The circuit is feedback adjusted in the whole adjusting range, has high control precision, and is not affected by load change.

[0083] The application provides a scanning electron microscope comprising the magnification adjusting circuit for a scanning electron microscope according to the first aspect or any of the corresponding embodiments.

[0084] The scanning electron microscope provided by the application has high calibration precision of the magnification of the scanning electron microscope.

[0085] Although the embodiments of the application are described in conjunction with the drawings, various modifications and changes can be made by those skilled in the art without departing from the spirit and scope of the application, and such modifications and changes fall within the scope defined by the appended claims.

Claims

1. A magnification adjustment circuit for a scanning electron microscope, characterized by, The amplification multiple adjusting circuit comprises a control circuit, an X scanning gear shifting circuit, an X scanning feedback circuit, a Y scanning gear shifting circuit and a Y scanning feedback circuit, wherein The control circuit is connected with an upper computer, the X scanning feedback circuit, the Y scanning feedback circuit, the X scanning gear shifting circuit and the Y scanning gear shifting circuit respectively, the X scanning gear shifting circuit is further connected with the X scanning feedback circuit, and the Y scanning gear shifting circuit is further connected with the Y scanning feedback circuit; The control circuit switches the amplification mode and amplification gear of the X scanning gear shifting circuit according to an X scanning control signal sent by the upper computer, and adjusts the gear current of the X scanning gear shifting circuit according to the deviation between the voltage signal fed back by the X scanning feedback circuit and the X scanning control signal, the amplification mode comprises three kinds, and each amplification mode comprises four amplification gears; The control circuit switches the amplification mode and amplification gear of the Y scanning gear shifting circuit according to a Y scanning control signal sent by the upper computer, and adjusts the gear current of the Y scanning gear shifting circuit according to the deviation between the voltage signal fed back by the Y scanning feedback circuit and the Y scanning control signal, the amplification mode comprises three kinds, and each amplification mode comprises four amplification gears; The X scanning gear shifting circuit and the Y scanning gear shifting circuit both comprise a mode switching circuit and a gear switching circuit, wherein The mode switching circuit is connected with the gear switching circuit, and the mode switching circuit and the gear switching circuit are both connected with the output end of the control circuit; The mode switching circuit is used for switching the amplification mode of the X scanning gear shifting circuit and the Y scanning gear shifting circuit, and the gear switching circuit is used for gear switching under each amplification mode; The gear switching circuit comprises a first switch, a second switch, a third switch, a fourth switch, a first resistor, a second resistor, a third resistor and a fourth resistor, wherein One end of the first switch is connected with one end of the second switch, one end of the third switch, one end of the fourth switch and the mode switching circuit respectively, and the other end of the first switch is connected with one end of the first resistor and one end of the second resistor respectively, and the other end of the first resistor is grounded; The other end of the second switch is connected with the other end of the second resistor and one end of the third resistor respectively, the other end of the third switch is connected with the other end of the third resistor and one end of the fourth resistor respectively, and the other end of the fourth switch is connected with the other end of the fourth resistor and the output end of the X / Y scanning feedback circuit.

2. The magnification adjustment circuit for a scanning electron microscope according to claim 1, wherein The gear switching circuit further comprises a fifth switch, a sixth switch, a seventh switch, an eighth switch, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, a thirteenth resistor, a fourteenth resistor, a fifteenth resistor, a sixteenth resistor and a seventeenth resistor, wherein One end of the fifth switch is connected with one end of the sixth switch, one end of the seventh switch, one end of the eighth switch and the mode switching circuit respectively, and the other end of the fifth switch is connected with one end of the fifth resistor, one end of the sixth resistor and one end of the scanning coil resistor respectively, and the other end of the fifth resistor is connected with one end of the seventh resistor and one end of the eighth resistor respectively; The other end of the sixth switch is connected with the other end of the seventh resistor, one end of the ninth resistor and one end of the tenth resistor respectively, and the other end of the ninth resistor is connected with one end of the eleventh resistor and one end of the twelfth resistor respectively; The other end of the seventh switch is connected with the other end of the eleventh resistor, one end of the thirteenth resistor and one end of the fourteenth resistor respectively, and the other end of the thirteenth resistor is connected with one end of the fifteenth resistor and one end of the sixteenth resistor respectively; The other end of the eighth switch is connected with the other end of the fifteenth resistor, one end of the seventeenth resistor and one end of the eighteenth resistor respectively, and the other end of the seventeenth resistor is connected with the other end of the eighteenth resistor, the other end of the sixteenth resistor, the other end of the fourteenth resistor, the other end of the twelfth resistor, the other end of the tenth resistor, the other end of the eighth resistor, the other end of the sixth resistor, the other end of the scanning coil resistor and the mode switching circuit respectively.

3. The magnification adjustment circuit for a scanning electron microscope according to claim 2, wherein The mode switching circuit comprises a ninth switch, a tenth switch, an eleventh switch, a twelfth switch, a thirteenth switch and a fourteenth switch, wherein, One end of the ninth switch is connected with one end of the tenth switch and one end of the eleventh switch respectively, and the other end of the ninth switch is connected with the other end of the fifth switch, one end of the fifth resistor, one end of the sixth resistor and one end of the scanning coil resistor respectively, and the other end of the tenth switch is connected with one end of the fifth switch, one end of the sixth switch, one end of the seventh switch and one end of the eighth switch respectively, and the other end of the eleventh switch is connected with the output end of the X / Y scan feedback circuit; One end of the twelfth switch is connected with one end of the thirteenth switch, one end of the fourteenth switch and the other end of the scanning coil resistor respectively, and the other end of the twelfth switch is connected with one end of the first switch, one end of the second switch, one end of the third switch and one end of the fourth switch respectively, and the other end of the thirteenth switch is connected with the other end of the fourth switch, the other end of the fourth resistor and the output end of the X / Y scan feedback circuit respectively, and the other end of the fourteenth switch is grounded.

4. The magnification adjustment circuit for a scanning electron microscope according to claim 3, wherein The X scan gear shifting circuit and the Y scan gear shifting circuit further comprise a first compensation circuit and a second compensation circuit, wherein, One end of the first compensation circuit is connected with the other end of the fifth switch, one end of the fifth resistor and one end of the sixth resistor respectively, and the other end of the first compensation circuit is connected with the other end of the ninth switch and one end of the scanning coil resistor respectively; One end of the second compensation circuit is connected with the other end of the sixth resistor and one end of the thirteenth switch respectively, and the other end of the second compensation circuit is connected with the other end of the scanning coil resistor and one end of the twelfth switch respectively.

5. The magnification adjustment circuit for a scanning electron microscope of claim 1, wherein, The control circuit comprises an MCU, an X control unit, an X power amplification unit, a Y control unit and a Y power amplification unit, wherein, The input end of the MCU is connected with the upper computer, and the output end of the MCU is connected with the input end of the X control unit, the input end of the Y control unit, the X scanning gear circuit and the Y scanning gear circuit respectively. The input end of the X control unit is also connected with the X scanning feedback circuit, the output end of the X control unit is connected with the input end of the X power amplification unit, the output end of the X power amplification unit is connected with the X scanning gear circuit, the input end of the Y control unit is also connected with the Y scanning feedback circuit, the output end of the Y control unit is connected with the input end of the Y power amplification unit, and the output end of the Y power amplification unit is connected with the Y scanning gear circuit.

6. A magnification adjustment method for a scanning electron microscope, characterized by, The magnification adjustment circuit for a scanning electron microscope according to any one of claims 1-5, the method comprising: The X scanning gear circuit is switched according to the X scanning control signal sent by the upper computer, and the Y scanning gear circuit is switched according to the Y scanning control signal sent by the upper computer, the amplification mode includes three kinds, and each amplification mode includes four amplification gears; The gear current of the X scanning gear circuit is adjusted according to the deviation between the voltage signal fed back by the X scanning feedback circuit and the X scanning control signal, and the gear current of the Y scanning gear circuit is adjusted according to the deviation between the voltage signal fed back by the Y scanning feedback circuit and the Y scanning control signal.

7. A scanning electron microscope characterized by comprising: The magnification adjustment circuit for a scanning electron microscope according to any one of claims 1-5.

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