JP2014093211A - Deflection device for charged particle beam and charged particle beam apparatus with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a deflection device for a charged particle beam which is stably operated even when an in-rush current or the like which flows in accordance with a noise component is generated, and a charged particle beam apparatus with the same.SOLUTION: The deflection device comprises: a deflection coil 3; an amplifier 26 in which a scan signal is inputted to an input terminal (+), for supplying a drive current corresponding to the scan signal to one end side 3a of the deflection coil 3; an error amplifier 23 in which the other end side 3b of the deflection coil 3 is connected to an input terminal 23a, and which feeds an output signal back to an input terminal (-) of the amplifier 26; a resistance element group 100 interposed between the input terminal 23a of the error amplifier 23 and a reference potential wire and formed from resistance elements R10-R40 which are connected in series; a relay 28 capable of selectively connecting any one of wires among the resistance elements R10-R40 and the reference potential wire to the other input terminal 23b of the error amplifier 23; and a relay 29 capable of connecting any one of the wires among the resistance elements R10-R40 in the resistance element group to the reference potential wire.

Description

  The present invention relates to a charged particle beam deflecting device used in a charged particle beam device such as a scanning transmission electron microscope (STEM) or a scanning electron microscope (SEM), and a charged particle beam device including the same.

  In a scanning transmission electron microscope using an electron beam as a charged particle beam, a focused electron beam is scanned on a sample, and at this time, transmitted electrons transmitted through the sample are detected by an electron detector. A STEM image is formed based on the transmission electron detection signal and the electron beam scanning signal.

  In a scanning electron microscope, a focused electron beam is scanned on a sample, and at this time, detected electrons such as secondary electrons or reflected electrons generated from the sample are detected by an electron detector. Based on the detection signal of the detected electrons and the scanning signal of the electron beam, an SEM image is formed.

  An electron microscope using such an electron beam includes a deflecting device for deflecting the electron beam and thereby scanning the electron beam on the sample.

  FIG. 1 shows an example (principal part) of a deflecting device in the prior art. As shown in the figure, the deflection apparatus includes a deflection coil 53 for deflecting an electron beam and an operational amplifier 56 for supplying a SCAN current (drive current) to one end side of the deflection coil 53. . The operational amplifier 56 includes a front-stage operational amplifier 51 and a rear-stage power amplifier 52.

  A non-inverting input terminal (+) of the operational amplifier 51 constituting the operational amplifier 56 is supplied with a SCAN signal composed of a sawtooth wave having a positive / negative maximum amplitude of ± 5 V from a scan generator (not shown). The output signal from the operational amplifier 51 is supplied to the power amplifier 52.

  The power amplifier 52 amplifies the output signal and supplies the amplified signal (SCAN current) to the one end side of the deflection coil 53. As a result, a drive current is supplied from the operational amplifier 56 to the deflection coil 53.

  The other end of the deflection coil 53 is connected to the inverting input terminal (−) of the operational amplifier 51. The operational amplifier 51 outputs an output signal so that there is no difference between the SCAN signal input to the non-inverting input terminal (+) and the signal (feedback signal) from the deflection coil 53 input to the inverting input terminal (−). To control.

  Further, a coarse magnification switching circuit 57 is provided between the other end of the deflection coil 53 and a ground wiring (GND wiring) serving as a reference potential. The coarse magnification switching circuit 57 includes a plurality of resistance elements R1 to R4 having different resistance values, and a switch 55 that can select any one of the resistance elements R1 to R4. The switch 55 has an open / close switch RY1 connected to the resistor element R1, an open / close switch RY2 connected to the resistor element R2, and an open / close switch RY3 connected to the resistor element R3.

  The switch 55 is supplied with a coarse magnification switching signal from a control means (not shown). Thereby, the switch 55 controls the open / close state of the open / close switches RY1 to RY3 based on the supplied coarse magnification switching signal. As a result, a current detection resistor corresponding to the coarse magnification is set between the other end of the deflection coil 53 and the ground wiring.

When the electron microscope is a scanning transmission electron microscope, the magnification of the acquired STEM image is about 10K times to 150M times and the setting range is wide. is there. Just by lowering the voltage in the SCAN signal supplied to the operational amplifier 51, it is impossible to perform the corresponding control.
Therefore, the current detection resistance is 5Ω (Mag 1: corresponding to 10K to 150K times), 50Ω (Mag 2: corresponding to 200K to 1.5M times), 500Ω (Mag 3: corresponding to 2M to 15M times), 5 kΩ (Mag 4: 20M). The switch 55 is controlled so that any one of the resistance values (corresponding to ~ 150M times) is set.

  Here, in the case of Mag1 in the low magnification range, only the open / close switch RY1 is closed (ON), and the current detection resistance is set to “5Ω // 5 kΩ≈5Ω”. In this case, since the maximum positive / negative amplitude of the SCAN signal is about ± 5 V, a current of about ± 1 A flows through the deflection coil 53 as the maximum current in the positive / negative direction. Here, “XΩ // YΩ” represents a combined resistance value when an XΩ resistor and a YΩ resistor are connected in parallel.

  In the case of Mag2 which is the next magnification range, only the open / close switch RY2 is closed and the current detection resistance is set to “50.5Ω // 5 kΩ≈50Ω”. In this case, a current of about ± 0.1 A flows through the deflection coil 53 as the maximum current in the positive and negative directions.

  Further, at Mag3 that is the next magnification range, only the open / close switch RY3 is closed and the current detection resistance is set to “555Ω // 5 kΩ≈500Ω”. In this case, a current of about ± 0.01 A flows through the deflection coil 53 as the maximum current in the positive and negative directions.

  When Mag4 is the next magnification range, all open / close switches RY1 to RY3 are opened (OFF), and the current detection resistance is set to “5 kΩ”. In this case, a current of about ± 1 mA flows through the deflection coil 53 as the maximum current in the positive and negative directions.

  When finer magnification setting (fine control) is performed in each magnification range set as the coarse magnification in this way, the absolute value of the maximum amplitude of the SCAN signal supplied to the operational amplifier 51 is adjusted appropriately. .

  In the above description, the larger the absolute value of the maximum current flowing through the deflection coil 53, the wider the scanning range by the electron beam on the sample. As a result, an image with a low magnification is acquired. On the other hand, the smaller the absolute value of the maximum current flowing through the deflection coil 53 is, the smaller the scanning range by the electron beam on the sample becomes. As a result, an image with a high magnification is acquired.

  In the above example, the deflecting device in the scanning transmission electron microscope has been described as an example. However, some deflecting devices in the scanning electron microscope have the same configuration (see Patent Document 1).

JP 2000-82438 A

  When the deflection device having the above configuration is used in a scanning transmission electron microscope or a scanning electron microscope, a relay is used as a switch 55 for switching the current detection resistance in the coarse magnification switching circuit 57 in accordance with the coarse magnification of the image. It has been. As this relay, a normal signal relay is often used.

  Recently, in order to reduce the noise of the SCAN current signal supplied to the deflection coil 53, a noise filter capacitor 54 connected in parallel with the deflection coil 53 is disposed as shown in FIG.

  In such a case, when the open / close state of the relay is switched based on the change in the coarse magnification, in a normal signal relay, an inrush current or the like flowing through the capacitor 54 according to the noise component is When flowing to the contact, the contact may be welded.

  As a result, the switching by the relay is hindered, and the coarse magnification switching circuit 57 does not operate normally.

  As a countermeasure, it is conceivable to use a relay with a large contact capacity such as a power relay as the switch 55.

  However, a commercially available power relay having a large contact capacity may be unstable because stability of contact resistance of the contact is neglected.

  In such a case, the voltage fed back from the deflection coil 53 to the operational amplifier 51 based on the operation of the coarse magnification switching circuit 57 becomes a voltage value detected by “(relay contact resistance) + (current detection resistance)”. As a result, fluctuations in the contact resistance of the relay contacts cause fluctuations in the SCAN current, making it impossible to acquire a stable image.

  The present invention has been made in view of the above points, and a charged particle beam deflecting device that stably operates even when an inrush current or the like flowing according to a noise component is generated, and a charging device including the same. An object is to provide a particle beam device.

  In one charged particle beam deflection apparatus according to the present invention, a scanning coil is input to a deflection coil for deflecting a charged particle beam and an input terminal, and a driving current corresponding thereto is supplied to one end side of the deflection coil. The other end of the deflection coil is connected to one input terminal, an error amplifier that feeds back an output signal to the input terminal of the amplifier, and an input between the input terminal of the error amplifier and the reference potential wiring, A resistance element group composed of a plurality of resistance elements connected in series and any one of the wiring between the resistance elements of the resistance element group and the reference potential wiring can be selectively connected to the other input terminal of the error amplifier. It is characterized by comprising first switching means and second switching means capable of selectively connecting any one of the wirings between the resistive elements of the resistive element group to the reference potential wiring.

  In another charged particle beam deflection apparatus according to the present invention, a scanning coil is input to a deflection coil for deflecting a charged particle beam and an input terminal, and a driving current corresponding to the scanning signal is supplied to one end side of the deflection coil. The other end of the deflection coil is connected to one input terminal via the first and second switching means, and the reference potential wiring is connected to the other input terminal. A plurality of error amplifiers that are connected to each other and that feed back an output signal to the input terminal of the amplifier, and are connected in parallel via the switching contacts of the second switching means between the other end of the deflection coil and the reference potential wiring. And a second switching means selects any one of the resistance elements in the resistance element group by closing any one of the switching contacts, and the selected resistance element Through the deflection carp And the first switching means connects the wiring between the open / close contact closed by the second switching means and the selected resistance element. It operates so as to be connected to one input terminal of the error amplifier.

  A charged particle beam apparatus according to the present invention includes any one of the above deflection apparatuses.

  In one charged particle beam deflection apparatus according to the present invention, feedback from a deflection coil is performed via an error amplifier, and a resistive element interposed between one input terminal of the error amplifier and a reference potential wiring First switching means capable of selectively connecting any one of the wirings between the resistive elements of the group and the reference potential wiring to the other input terminal of the error amplifier, and each of the resistive element groups Second switching means is provided that can selectively connect any one of the wirings between the resistive elements to the reference potential wiring.

  With this configuration, the first switching means is disposed at a position that affects the stability of the drive current supplied to the deflection coil, and the second switching means is disposed at a position that should correspond to the inflow of a large current. Therefore, the first switching means can be a switching means having a stable contact resistance, and the second switching means can be a switching means having a large contact capacity, and an inrush current or the like flowing according to the noise component is generated. However, a charged particle beam deflecting device that operates stably can be provided.

  Also in another charged particle beam deflecting device according to the present invention, feedback from the deflection coil is performed via an error amplifier, and there is a first place where the stability of the drive current supplied to the deflection coil is affected. Since the second switching means is arranged at a location that should correspond to the inflow of a large current, the same effect as described above can be obtained.

It is a figure which shows an example (principal part) of the deflection apparatus of the charged particle beam in a prior art. It is a figure which shows schematic structure of the scanning transmission electron microscope as an example of a charged particle beam apparatus. It is a figure which shows the principal part of the deflection | deviation apparatus of the charged particle beam in 1st Example of this invention. It is a figure which shows the principal part of the deflection | deviation apparatus of the charged particle beam in 2nd Example of this invention.

  Hereinafter, a charged particle beam deflection apparatus and a charged particle beam apparatus including the same according to the present invention will be described with reference to the drawings.

  FIG. 2 is a schematic configuration diagram showing the configuration of the charged particle beam apparatus according to the present invention. The charged particle beam apparatus has a configuration of a scanning transmission electron microscope (STEM) in this embodiment.

  An electron beam (charged particle beam) 11 accelerated and emitted from the electron gun 1 is focused by the focusing lens 2 and further focused on the sample 7 by the pre-stage magnetic field of the objective lens 4. As a result, a focused electron beam is formed on the surface of the sample 7.

  At this time, due to the deflection action by the deflection coil 3, the focused electron beam 11 sequentially moves through the scanning points in the scanning area set on the surface of the sample 7 and scans the sample 7. Thereby, the deflection coil 3 serves as a scanning coil (SCAN coil).

  A scanning driving current (SCAN current) is supplied to the deflection coil 3 from the scanning driving means 8. The scan driver 8 is supplied with a SCAN signal from the scan generator 9. Further, the scan generator 9 sends the SCAN signal to the image forming unit 19.

  At each scanning point of the sample 7 scanned with the focused electron beam 11, electrons (transmission electrons) 12 transmitted through the sample 7 are applied to the light receiving surface of the electron detector 6 by the subsequent magnetic field of the objective lens 4 and the magnetic field of the projection lens 5. Focused.

  A detection signal of transmitted electrons 12 detected by the electron detector 6 is sent to the image forming means 10. The image forming unit 10 forms a scanning image (STEM image) by synchronizing the detection signal and the SCAN signal. The scan image formed in this way is displayed by display means (not shown).

  The scanning drive unit 8, the scan generator 9, the image forming unit 10, and the like are controlled by a control unit (not shown).

  Next, the configuration of the charged particle beam deflecting device in the first embodiment of the present invention will be described with reference to FIG. The deflection apparatus of the present invention includes the above-described deflection coil 3 and an operational amplifier 26 for supplying a SCAN current to one end side 3 a of the deflection coil 3. The operational amplifier 26 includes a front-stage operational amplifier 21 and a rear-stage power amplifier 22.

  The non-inverting input terminal (+) of the operational amplifier 21 constituting the operational amplifier 26 is supplied with a SCAN signal composed of a sawtooth wave having a maximum positive / negative amplitude of ± 5 V from the scan generator 9 (see FIG. 2). The output signal from the operational amplifier 21 is supplied to the power amplifier 22.

  The power amplifier 22 amplifies the output signal and supplies the amplified signal (SCAN current) to the one end side 3 a of the deflection coil 3. As a result, a driving current is supplied from the operational amplifier 26 to the deflection coil 3.

  The other end 3 b of the deflection coil 3 is connected to the inverting input terminal (−) of the operational amplifier 21 through the error amplifier 23. The operational amplifier 21 controls the output signal so that there is no difference between the SCAN signal input to the non-inverting input terminal (+) and the signal (feedback signal) input to the inverting input terminal (−).

  The other input side 23b of the deflection coil 3 is connected to one input terminal 23a of the error amplifier 23. Between the other end side 3b and a ground wiring (GND wiring) serving as a reference potential, a coarse magnification is provided. A switching circuit 27 is provided.

  The coarse magnification switching circuit 27 includes a plurality of resistance elements (resistances) R10 to R40 having different resistance values connected in series, a first switching means 28 made of a signal relay, and a second switching means 29 made of a power relay. With. The resistance values of the resistors R10, R20, R30, and R40 are 5Ω, 45Ω, 450Ω, and 4.5 kΩ, respectively.

  The first switching unit 28 has a function of selectively connecting any one of the wiring between the resistors R <b> 10 to R <b> 40 and the ground wiring to the other input terminal 23 b in the error amplifier 23.

  Here, the first switching means 28 has open / close switches RY1.1 to RY4.1. The open / close switch RY1.1 is disposed between the wiring between the resistors R10 and R20 and the input terminal 23b. The open / close switch RY2.1 is disposed between the wiring between the resistors R20 and R30 and the input terminal 23b. The open / close switch RY3.1 is disposed between the wiring between the resistors R30 and R40 and the input terminal 23b. The open / close switch RY4.1 is disposed between the ground wiring and the input terminal 23b.

  The first switching unit 28 operates to close any one of the open / close switches RY1.1 to RY4.1 provided therein based on the coarse magnification signal supplied from the control unit.

  The second switching unit 29 has a function of selectively connecting any one of the wires between the resistors R10 to R40 to the ground wire.

  Here, the second switching means 29 has open / close switches RY1.2 to RY3.2. The open / close switch RY1.2 is disposed between the wiring between the resistors R10 and R20 and the ground wiring. The open / close switch RY2.2 is disposed between the wiring between the resistors R20 and R30 and the ground wiring. The open / close switch RY3.2 is disposed between the wiring between the resistors R30 and R40 and the ground wiring.

  Based on the coarse magnification signal supplied from the control means, the second switching means 29 closes any one of the on-off switches RY1.2 to 3.2 provided therein or opens all the switches. To work.

  In the scanning drive means 8 having the above configuration, a noise filter capacitor 24 is disposed between one input terminal 23 a of the error amplifier 23 and the output terminal of the power amplifier 22. Further, a high resistance element 25 of about 1 MΩ is disposed between the other input terminal 23 b of the error amplifier 23 and the ground wiring.

  The above is the configuration of the charged particle beam deflecting device of the present invention. Next, the operation will be described.

  The control means controls the operation of the first and second switching means 28 and 29 in the scanning drive means 8 based on the coarse magnification selected by the operator of the apparatus.

  In this example, as in the prior art example, the current detection resistance is 5Ω (Mag 1: corresponding to 10K to 150K times), 50Ω (Mag 2: corresponding to 200K to 1.5M times), 500Ω (Mag 3: 2M to Each resistance value of 5 kΩ (corresponding to Mag4: 20M to 150M times) is set.

  The SCAN signal is supplied from the scan generator 9 to the non-inverting input terminal (+) of the operational amplifier 21 constituting the operational amplifier 26. The SCAN signal is a sawtooth wave signal having a maximum positive / negative amplitude of about ± 5 V, as in the prior art.

  First, when acquiring an image in Mag1, which is a low-magnification range, the control unit closes only the switch RY1.1 in the first switching unit 28 and switches the switch RY1.2 in the second switching unit 29. Control to close only.

  In this state, the SCAN current supplied from the power amplifier 22 of the operational amplifier 26 to the deflection coil 3 flows to the ground wiring via the resistor R10 that becomes the current detection resistor 5Ω. At this time, since the SCAN signal has a maximum positive / negative amplitude of about ± 5 V as described above, a current of about ± 1 A flows through the deflection coil 3 as the maximum current in the positive / negative direction.

  A magnetic field corresponding to the current width is generated in the deflection coil 3, and the electron beam 11 is deflected (scanned) in accordance with this. Since the deflection width of the electron beam 11 at this time increases corresponding to the current width, a low-magnification scanning image is acquired.

  At this time, since the switch RY1.1 is closed, the error amplifier 23 detects the voltage across the 5Ω current detection resistor (R10) and feeds back the voltage to the operational amplifier 21.

  On the other hand, when acquiring an image in Mag2 which is the next magnification range, the control means closes only the switch RY2.1 in the first switching means 28 and only the switch RY2.2 in the second switching means 29. Control to close.

  In this state, the SCAN current supplied from the power amplifier 22 of the operational amplifier 26 to the deflection coil 3 flows to the ground wiring via the series combined resistance of the resistors R10 and R20 that become the current detection resistance 50Ω. At this time, since the SCAN signal has a maximum positive / negative amplitude of about ± 5 V as described above, a current of about ± 0.1 A flows through the deflection coil 3 as the maximum current in the positive / negative direction.

  A magnetic field corresponding to the current width is generated in the deflection coil 3, and the electron beam 11 is deflected (scanned) in accordance with this. The deflection width of the electron beam 11 at this time is a width corresponding to the current width, and a scanning image with a magnification corresponding to the current width is acquired.

  At this time, since the switch RY2.1 is closed, the error amplifier 23 detects the voltage across the 50Ω current detection resistor (R10 + R20) and feeds back the voltage to the operational amplifier 21.

  Further, when acquiring an image in Mag3 which is the next magnification range, the control means closes only the switch RY3.1 in the first switching means 28 and only the switch RY3.2 in the second switching means 29. Control to close.

  In this state, the SCAN current supplied from the power amplifier 22 of the operational amplifier 26 to the deflection coil 3 flows to the ground wiring via the series combined resistance of the resistors R10, R20, and R30 that become the current detection resistance 500Ω. At this time, since the SCAN signal has a maximum positive / negative amplitude of about ± 5 V as described above, a current of about ± 0.01 A flows through the deflection coil 3 as the maximum current in the positive / negative direction.

  A magnetic field corresponding to the current width is generated in the deflection coil 3, and the electron beam 11 is deflected (scanned) in accordance with this. The deflection width of the electron beam 11 at this time is a width corresponding to the current width, and a scanning image with a magnification corresponding to the current width is acquired.

  At this time, since the switch RY3.1 is closed, the error amplifier 23 detects the voltage across the 500Ω current detection resistor (R10 + R20 + R30) and feeds back the voltage to the operational amplifier 21.

  When acquiring an image at Mag4 which is the next magnification range, the control means closes only the switch RY4.1 in the first switching means 28 and all the switches RY1. Control is performed to open 2 to RY3.2.

  In this state, the SCAN current supplied from the power amplifier 22 of the operational amplifier 26 to the deflection coil 3 flows to the ground wiring via the series combined resistance of the resistors R10, R20, R30, and R40 that become the current detection resistance 5 kΩ. . At this time, since the SCAN signal has a maximum positive / negative amplitude of about ± 5 V as described above, a current of about ± 1 mA flows through the deflection coil 3 as the maximum current in the positive / negative direction.

  A magnetic field corresponding to the current width is generated in the deflection coil 3, and the electron beam 11 is deflected (scanned) in accordance with this. The deflection width of the electron beam 11 at this time is a width corresponding to the current width, and a scanning image with a magnification corresponding to the current width is acquired.

  At this time, since the switch RY4.1 is closed, the error amplifier 23 detects the voltage across the 5 kΩ current detection resistor (R10 + R20 + R30 + R40) and feeds back the voltage to the operational amplifier 21.

  The above is the switching control based on the coarse magnification. When finer magnification is set, the coarse magnification is set as described above, and the absolute value of the maximum amplitude in the SCAN signal supplied from the scan generator 9 to the operational amplifier 21 is appropriately reduced based on the control of the control means. Adjusted.

  In the above configuration, since the input impedance of the error amplifier 23 is so large as to be infinite, any one of the switches RY1.1, RY2.1, RY3.1, RY4.1 of the first switching means 28 is set. Even when it is turned on (closed), almost no current flows to the ground wiring side through the switch that is turned on, and there is no need to worry about the occurrence of welding of the relay contact due to inrush current or the like.

  Therefore, as the first switching means 28, a signal relay in which the contact resistance of the contact is stable can be used.

  Further, when the switches RY1.2, RY2.2, and RY3.2 of the second switching unit 29 are turned on, a large current such as an inrush current flows.

  Therefore, as the second switching means 29, a power relay is used because a relay having a sufficiently large contact capacity needs to be used so that contact welding does not occur even when an inrush current or the like flows.

  Here, when a power relay is used as the second switching means 29, the contact resistance of the contact may be increased.

  As described above, in the conventional example of FIG. 1, the voltage fed back to the operational amplifier 51 is a voltage value detected by “(relay contact resistance + current detection resistance)”. Minutes cause fluctuations in the SCAN current.

  In this respect, in the present embodiment, the error amplifier 23 detects only the voltage generated at both ends of the current detection resistor, so that the voltage fed back to the operational amplifier is not affected by the fluctuation of the contact resistance of the contact of the power relay.

  Therefore, even if the contact resistance at the contact of the second switching means 29 (power relay: RY1.2, RY2.2, RY3.2) increases or varies, the feedback control is affected by the increase or variation of the contact resistance. It is done stably without.

  As a result, the voltage between the input terminals 23a and 23b is not affected, and feedback to the operational amplifier 21 is favorably performed.

  In the above embodiment, the deflecting device is applied to a scanning transmission electron microscope. However, the present invention is not limited to this. In addition, for example, the deflection device can be applied to a scanning electron microscope.

  In this way, in the charged particle beam deflecting device of the present invention, the scanning signal is input to the deflection coil 3 for deflecting the charged particle beam 11 and the input terminal (+), and the drive current corresponding to this is supplied. An amplifier (operational amplifier) 26 for supplying to one end side 3a of the deflection coil 3, and the other end side 3b of the deflection coil 3 is connected to one input terminal 23a, and an output signal is supplied to the input terminal (−) of the amplifier 26. An error amplifier 23 to be fed back, a resistor element group 100 including a plurality of resistor elements R10 to R40 connected in series between an input terminal 23a of the error amplifier 23 and a reference potential wiring (ground wiring); First switching means 28 capable of selectively connecting any one of the wiring between the resistance elements R10 to R40 of the group 100 and the reference potential wiring to the other input terminal 23b of the error amplifier 23; And a second switching means 29 selectively connectable to a reference potential wiring any one of the wiring in the wiring between the resistor elements R10~R40 resistive element group.

  Here, a noise filter 24 is connected in parallel to the deflection coil 3. Further, a high resistance element 25 is disposed between the other input terminal 23 b of the error amplifier 23 and the reference potential wiring.

  Next, referring to FIG. 4, the configuration of the charged particle beam deflecting device in the second embodiment of the present invention will be described.

  As shown in the figure, the deflection apparatus has a deflection coil 3 for deflecting a charged particle beam, and a scanning signal is inputted to an input terminal, and a driving current corresponding to the scanning signal is supplied to one end side 3 a of the deflection coil 3. The other end side 3b of the deflection coil 3 is connected to one input terminal 33a via the first and second switching means 38, 39, and the first and second switching means 38, 39. The reference potential wiring is connected to the other input terminal 33b, the error amplifier 33 that feeds back the output signal to the input terminal of the amplifier 26, and the other end side 3b of the deflection coil 3 and the reference potential wiring. Resistor elements comprising a plurality of resistor elements R11 to R41 (R11: 5Ω, R21: 50Ω, R31: 500Ω, R41: 5kΩ) connected in parallel via the switching contacts RY1.2 to RY4.2 of the two switching means Group 101 and The second switching means 39 selects any one resistance element in the resistance element group 101 by closing any one of the switching contacts, and the deflection coil 3 is selected via the selected resistance element. The first switching means 38 operates between the other end side 3b and the reference potential wiring, and the first switching means 38 is connected between the switching contact closed by the second switching means 39 and the selected resistance element. It operates so as to connect the wiring to one input terminal 33 a of the error amplifier 33.

  This embodiment differs from the first embodiment described above in that in the first embodiment, four current detection resistors are connected in series and each current detection resistor is short-circuited one by one by the second switching means. In this embodiment, the resistance value is changed in four stages. In this embodiment, four current detection resistors having different resistance values are individually switched by the second switching means and connected to the deflection coil. It is.

  In other words, in the configuration of FIG. 4, by closing any of the switching contacts RY1.2 to RY4.2 of the second switching means, the deflection coil 3 is selectively connected to a resistor connected to the closed contact. At the same time, the switching contacts RY1.1 to RY4.1 of the first switching means are also closed at the contacts connected to the resistance connected to the deflection coil 3.

  For example, when the current detection resistor R11 is selected, since the switching contact RY1.2 of the second switching unit and the switching contact RY1.1 of the first switching unit are closed, the current detection resistor R11 is generated at both ends of the current detection resistor R11. The voltage is transmitted to the error amplifier 33 via the switching contact RY1.1, and the operational amplifier 26 performs feedback control based on the output of the error amplifier 33 and the input SCAN signal.

  Also in this embodiment, since the input impedance of the error amplifier is so large that it can be said that it is infinite, almost no current flows through the switching contacts RY1.1 to RY4.1 of the first switching means, and attention should be paid to the welding of the relay contacts. It is possible to use a signal relay which does not need to be paid and whose contact resistance of the contact is stable.

  Even if a power relay such as a power relay that has a sufficiently large contact capacity and allows a large current to flow is used as the second switching means, the error amplifier detects the voltage across the current detection resistor and feeds it back. Even if the contact resistance of the contact of the power relay is large or unstable, the detection voltage is not affected by it. Therefore, feedback control based on the output of the error amplifier 33 and the input SCAN signal is favorably performed by the operational amplifier 26.

  In the present invention, since the power relay having a sufficiently large contact capacity is used for the switching means (second switching means) that may cause a large current to flow, the occurrence of an operation failure due to contact welding is reliably prevented. be able to.

  Further, since the switching means (first switching means) that affects the stability of the drive current (SCAN current) uses a signal relay in which the contact resistance of the contact is stable, it depends on the contact resistance of the relay contact. The deterioration of the stability of the circuit can be prevented.

  Furthermore, it is not necessary to use a special relay that has a large contact capacity and stable contact resistance, and the present invention can be implemented by using an inexpensive commercially available relay (power relay, signal relay). is there.

  At this time, since the power relay only needs to consider the contact capacity, and the signal relay only needs to consider the contact resistance of the contact, the range of selection is widened when selecting these relays.

DESCRIPTION OF SYMBOLS 1 ... Electron gun, 2 ... Focusing lens, 3 ... Deflection coil, 4 ... Objective lens, 5 ... Projection lens, 6 ... Electron detector, 7 ... Sample, 8 ... Scanning drive means, 9 ... Scan generator, 10 ... Image formation Circuit 21... Operational amplifier 22... Power amplifier 23. Error amplifier 24. Noise filter 25 25 High resistance element 26 Operational amplifier 27 27 Coarse magnification switching circuit 28 28 1st switching means 29 29 2 switching means, 33 ... error amplifier, 38 ... first switching circuit, 39 ... second switching circuit, 100 ... resistance element group, 101 ... resistance element group, R10-R40 ... resistance element, R11-R41 ... resistance Element, GND: Ground wiring (reference potential wiring)

Claims (7)

  A deflection coil for deflecting the charged particle beam, an amplifier for inputting a scanning signal to the input terminal and supplying a drive current corresponding to the scanning signal to one end side of the deflection coil, and another deflection coil at one input terminal An error amplifier that is connected to the input side and feeds back an output signal to the input terminal of the amplifier, and a resistor element group that is interposed between the input terminal of the error amplifier and the reference potential wiring and includes a plurality of resistance elements connected in series; First switching means capable of selectively connecting any one of the wiring between the resistance elements of the resistance element group and the reference potential wiring to the other input terminal of the error amplifier, and each resistance element of the resistance element group A charged particle beam deflecting device comprising: a second switching unit capable of selectively connecting any one of the wirings in between to the reference potential wiring.   2. The charged particle beam deflecting device according to claim 1, wherein a high resistance element is disposed between the other input terminal of the error amplifier and the reference potential wiring.   A deflection coil for deflecting a charged particle beam, an amplifier for inputting a scanning signal to an input terminal and supplying a drive current corresponding to the scanning signal to one end of the deflection coil, and first and second switching means, The error in which the other end side of the deflection coil is connected to one input terminal via the first and second switching means, the reference potential wiring is connected to the other input terminal, and the output signal is fed back to the input terminal of the amplifier. An amplifier, and a resistance element group composed of a plurality of resistance elements connected in parallel via the switching contacts of the second switching means between the other end side of the deflection coil and the reference potential wiring, The switching means selects any one resistance element in the resistance element group by closing any one of the switching contacts, and the other end side of the deflection coil and the reference potential wiring are selected via the selected resistance element. Move to connect At the same time, the first switching means operates to connect the wiring between the open / close contact closed by the second switching means and the selected resistance element to one input terminal of the error amplifier. Particle beam deflecting device.   4. The charged particle beam deflecting device according to claim 1, wherein a noise filter is connected in parallel to the deflection coil.   5. The charged particle beam deflecting device according to claim 1, wherein the first switching means is a signal relay, and the second switching means is a power relay.   6. The charged particle beam deflection apparatus according to claim 1, wherein the charged particle beam is an electron beam.   A charged particle beam apparatus comprising the charged particle beam deflecting device according to claim 1.

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