JP5331073B2 - Electron beam equipment - Google Patents

Description

  The present invention relates to an electron beam apparatus, and more particularly to an electron beam apparatus capable of suppressing contamination of a differential exhaust diaphragm regardless of a probe current value.

  In an electron beam apparatus typified by a scanning electron microscope, various observation condition parameters are set in accordance with a sample, an observation condition, and the like, and an enlarged image of the sample is observed. Observation condition parameters include, for example, acceleration voltage, electron gun emission current, convergence lens condition, working distance (distance between objective lens and sample), sample observation image signal detection system condition, objective aperture diameter Etc.

  In addition, the electron beam apparatus is used for analyzing a minute region on a sample by combining with various analysis apparatuses. Examples of analytical methods include energy-dispersive X-ray spectroscopy (EDX), wavelength-dispersive X-ray spectroscopy (WDX), and backscattered electron diffraction. There is an electron backscatter diffraction pattern (EBSP) method.

  The EDX method is a method in which characteristic X-rays generated from a sample are directly detected by a semiconductor detector and converted into an electric signal for spectroscopic analysis. A pulse current proportional to the energy of the detected characteristic X-rays is generated, and this is generated. Select and measure with a multichannel wave height analyzer.

  The WDX method is a method of performing spectroscopic analysis of characteristic X-rays generated from a sample by separating and detecting X-rays having a specific wavelength using Bragg reflection in the spectroscopic crystal. The X-ray wavelength is measured from the diffraction angle, and the type of element is identified.

  In the EBSP method, since the Kikuchi pattern created by inelastic backscattered electrons from the sample changes depending on the orientation of the sample, the pattern is analyzed by scanning the sample with an incident electron probe, This is a method for obtaining a crystal orientation distribution image of a polycrystalline sample.

  When carrying out these analysis methods, it is necessary to make the current (probe current Ip) value of the electron beam irradiated to the sample larger than when simply obtaining an enlarged image of the sample. For example, the probe current Ip for high-resolution observation may be several [pA] to several tens [pA], but several hundred [pA] in the EDX method, several [nA] in the EBSP method, and several tens [in the WDX method] nA] or so.

  In general, the higher the charge of the irradiated electron beam, and the lower the degree of vacuum at the portion irradiated with the electron beam (the higher the remaining internal pressure), the more the contamination inside the electron beam apparatus such as each aperture. Is likely to increase. That is, it is easier to contaminate the inside of the apparatus by analyzing the sample than by observing an enlarged image of the sample.

  Generally, in an electron beam apparatus, the inside of a body part on which a sample is placed is kept in a high vacuum, and the inside of an electron gun part including a cathode that emits electrons is lower in pressure than the inside of the body part. Keep in state. In order to pass the electron beam, the inside of the electron gun portion and the inside of the mirror body portion communicate with each other through a small opening called a differential exhaust diaphragm.

  Therefore, the opening diameter of the differential exhaust diaphragm is preferably set to a minimum size from the viewpoint of not affecting the optical system and suppressing the inflow and outflow of substances such as gas. In other words, contamination of the differential exhaust diaphragm can cause immediate deterioration of the optical performance of the electron beam apparatus.

  Therefore, conventionally, when a long diaphragm plate is wound around one shaft and the other shaft is rotated to wind up this diaphragm plate, the throttle hole drilled in the surface of the diaphragm plate crosses the hole made in the case. Thus, there has been proposed a movable diaphragm device for an electron microscope or the like that can be replaced with the next diaphragm hole even if one diaphragm hole is contaminated (see, for example, Patent Document 1).

  Also, when the total charge amount of the primary electron beam hitting the aperture plate exceeds a predetermined reference value, it is determined that the contamination of the aperture hole (contamination) has exceeded an allowable limit value that does not affect the image quality, A charged particle beam apparatus that switches an aperture hole with an actuator has been proposed (see, for example, Patent Document 2).

  In addition, a diaphragm plate having a diaphragm hole and a thick plate having a hole portion and laminated on the diaphragm plate are subjected to flushing by applying a high voltage to the diaphragm plate by a voltage applying means to remove contaminants attached to the diaphragm plate. A scanning electron microscope to be removed has been proposed (see, for example, Patent Document 3).

Japanese Patent Laid-Open No. 11-233053 (paragraphs 0012 to 0014, FIG. 2) Japanese Patent Laying-Open No. 2004-94559 (paragraph 0021, FIG. 2) Japanese Unexamined Patent Publication No. 2000-200574 (paragraph 0019, FIG. 1)

  However, in the conventional movable diaphragm device for an electron microscope or the like (described in Patent Document 1), the case and the diaphragm plate slide, so that leakage of gas or the like is likely to occur at the sliding portion, and the differential exhaust diaphragm There is a problem that it is not appropriate to use as.

  Further, the conventional charged particle beam device (described in Patent Document 2) includes a mechanism for switching the aperture hole with an actuator. This mechanism also has a risk that gas or the like may leak at the switching portion, and the structure of the differential exhaust throttle portion is complicated, so that it is difficult to use for this portion.

  In the conventional scanning electron microscope (described in Patent Document 3), in order to effectively prevent the contamination of the diaphragm plate, the thickness of the thick plate must be increased, and a high voltage for flushing is required. Therefore, the periphery of the diaphragm plate must have a high insulation structure. Therefore, there is a problem that it is difficult to adopt such a configuration for the differential exhaust diaphragm which is a place where the high vacuum atmosphere and the ultra-high vacuum atmosphere are in contact with each other and also needs to maintain an optically precise positional relationship. .

  In addition, any of the above-described conventional techniques basically takes a countermeasure after the throttle hole is contaminated. In particular, when the probe current is large, there is a problem that the contamination of the differential exhaust throttle also increases. For these reasons, there is a difference from the viewpoint of obtaining a reduction in the degree of vacuum and fluctuations in optical performance by giving an excessive margin to the aperture diameter of the aperture, simplifying the structure, ease of operation, maintenance, and management. There has been a demand for a technique that suppresses the attachment of contaminants to the throttle instead of replacing or decontaminating the dynamic exhaust throttle each time it is contaminated.

  Accordingly, an object of the present invention is to provide an electron beam apparatus that can suppress contamination of a differential exhaust diaphragm regardless of the magnitude of the probe current, in view of such problems of the prior art.

In order to solve the above problems, an electron beam apparatus of the present invention includes an electron gun that has an electron source and generates a primary electron beam, an electron gun part that contains the electron gun, and a mirror part that contains a sample. A differential exhaust diaphragm that communicates with each other, and a converging lens that is provided in the electron gun section and converges the primary electron beam to form a crossover point on or near the opening surface of the differential exhaust diaphragm. An aperture mechanism that is arranged in an optical path from the electron gun to the convergent lens and that can switch an aperture diameter; a switching mechanism that switches the aperture diameter of the aperture mechanism; and at least the convergent lens connected to an input device and a display device And a computer for controlling the position of the crossover point within a predetermined range in accordance with the mode of operation selected via the input device. The aperture diameter of the aperture mechanism capable of narrowing the extent of the primary electron beam to a size that does not irradiate the peripheral edge of the aperture of the differential exhaust aperture is selected. The display device is characterized in that a display for prompting is displayed.

According to the electron beam equipment of the present invention, to place the switchable diaphragm mechanism opening diameter between the electron source and the converging lens, since to switch the opening diameter corresponding to the position of the cross-over point, Regardless of the probe current value, contamination of the differential exhaust throttle can be suppressed.

It is explanatory drawing explaining the problem which generate | occur | produces when changing a probe electric current in the electron beam apparatus of a comparative example. 1 is a configuration block diagram showing an electron beam apparatus according to a first embodiment of the present invention. FIG. 3 is a partial optical path explanatory diagram showing the relationship between the crossover position b1 and the probe current Ip. 6 is a graph showing a change in probe current Ip with respect to the crossover position b1 of the first converging lens 6 and a graph showing a change in beam spread on the aperture surface of the differential exhaust diaphragm 33 with respect to the crossover position b1. It is a screen figure which shows an example of the warning display displayed on a display apparatus. It is a block diagram which shows the electron beam apparatus of 2nd Embodiment by this invention. It is a block diagram which shows the electron beam apparatus of 3rd Embodiment by this invention.

Next, an embodiment of the present invention will be described in detail with reference to the drawings.
First, a problem that occurs when the probe current Ip is changed in the electron beam apparatus 105 of the comparative example will be described with reference to FIG.

  The electron beam apparatus 105 includes a mirror part 32 in which the internal space is maintained at a high vacuum, an electron gun part 31 in which the internal space is maintained at an ultrahigh vacuum whose atmospheric pressure is lower than that of the mirror part 32, and a mirror part. 32 and a differential exhaust throttle 33 that communicates the internal space of the electron gun unit 31 with the internal space of the electron gun unit 31.

  The electron gun unit 31 includes an electron source 51, a diaphragm 53 placed immediately below the electron source 51, and a converging lens (condenser lens) 55 for converging the primary electron beam 3 emitted from the electron source 51. Yes. In addition, the mirror part 32 includes an objective aperture 7 for limiting the amount of probe current.

  In the electron beam apparatus 105, the three bundles of primary electron beams emitted from the electron source 51 pass through a diaphragm 53 immediately below the electron source 51, and are once converged by a converging lens (condenser lens) 55 and spread again. The spread bundle of primary electron beams 3 is limited by the objective aperture 7 and a part thereof is blocked, whereby the current value (≈probe current Ip) of the primary electron beam 3 after passing through the objective aperture 7 is defined.

  The point where the bundle of primary electron beams 3 is once converged by the converging lens 55, that is, the crossover point 56 is adjusted by adjusting the amount of current passed through the magnetic field coil (not shown) of the converging lens 55. It can be moved back and forth along the optical axis direction.

  Therefore, as shown in FIG. 1A, the probe current Ip decreases as the crossover point 56 is moved away from the objective aperture 7 (the opening surface thereof, hereinafter the same in this paragraph). Then, as shown in FIG. 1B, the probe current Ip increases as the crossover point 56 is brought closer to the objective aperture 7, and when the crossover point 56 and the objective aperture 7 are in the same plane, the probe current is increased. Ip is substantially equal to the current value of the primary electron beam 3 that has passed through the diaphragm 53. Thus, the probe current Ip can be adjusted by controlling the converging lens 55 and moving the crossover point 56 back and forth.

  Some scanning electron microscopes, which are a kind of electron beam apparatus 105, have a configuration in which a dedicated mode called “observation mode” or “analysis mode” can be selected. In this scanning electron microscope, an appropriate value of the probe current Ip is set by controlling the converging lens 55 in accordance with the selected mode. For example, when the “observation mode” is set, the drive current of the converging lens 55 is increased, so that the crossover point 56 is moved away from the objective aperture 7 and a small probe current Ip for sample observation is obtained. When the “analysis mode” is set, since the current of the converging lens 55 is reduced, the crossover point 56 approaches the objective aperture 7 and a large probe current Ip for sample analysis is obtained.

  As shown in FIG. 1C, when the crossover point 56 is further away from the objective aperture 7, the primary electron beam 3 bundle is larger than the aperture diameter of the differential exhaust aperture 33 on the opening surface of the differential exhaust aperture 33. In some cases, a part of the bundle of three primary electron beams reaches the differential exhaust diaphragm 33 itself. When the primary electron beam 3 is irradiated, the differential exhaust diaphragm 33 is contaminated. If the opening of the differential exhaust diaphragm 33 is contaminated, the aperture diameter of the diaphragm becomes small, the probe current Ip decreases, the opening shape is distorted, and abnormal astigmatism occurs. A failure occurs, and the performance of the electron beam apparatus 105 decreases.

  The diaphragm 53 just below the electron source 51 is in an ultra-high vacuum atmosphere even when the primary electron beam 3 is irradiated, so that contamination is hardly generated. The objective aperture 7 is contaminated when irradiated with the primary electron beam 3, but is relatively easy to replace due to its structure, and can be decontaminated with a heating mechanism.

  However, since the differential exhaust diaphragm 33 is in contact with the internal space of the mirror part 32 having a lower degree of vacuum (higher residual pressure) than the electron gun part 31, contamination is likely to occur due to the irradiation of the primary electron beam 3. In addition, the exchange of the differential exhaust diaphragm 33 is performed after the entire electron gun section 31 is once removed from the mirror body section 32, which is troublesome and difficult to perform. Furthermore, since it is interposed at the boundary between the electron gun section 31 and the mirror body section 32, it is difficult to provide a heating mechanism for decontamination. For this reason, there is a problem that it is difficult to keep the differential exhaust throttle 33 clean.

  The electron beam apparatus 105 needs to appropriately set the probe current Ip of the electron probe that scans the sample depending on the purpose of use such as observation and analysis. Further, regardless of the magnitude of the probe current Ip, it is necessary to prevent the differential exhaust diaphragm 33 from being contaminated and to prevent the performance of the electron beam apparatus 105 from being deteriorated.

  Therefore, the inventor of the present application paid attention to prevent the primary exhaust beam 33 from being irradiated to the differential exhaust diaphragm 33 in order to keep the differential exhaust diaphragm 33 clean. In order to change the probe current Ip while preventing the primary electron beam 3 from being applied to the differential exhaust diaphragm 33, for example, the following may be considered.

(1) The control range of the position of the crossover point 56 is limited to a range in which the three primary electron beam bundles do not reach the plate of the differential exhaust diaphragm 33.
(2) A diaphragm 53 having a small opening diameter is used as the diaphragm 53 directly below the electron source 51 to reduce the spread of the primary electron beam 3 bundle at the position of the differential exhaust diaphragm 33.
(3) The opening diameter of the differential exhaust diaphragm 33 is increased so that the bundle of primary electron beams 3 does not hit the differential exhaust diaphragm 33.

  For example, in the above (1), the dynamic range of the probe current Ip is extremely limited, so that there is a problem that a desired observation and analysis method cannot be taken. Further, in (2), there is a problem that the maximum value of the probe current Ip is limited to be small. Further, in the above (3), there is a problem that leakage of substances such as gas from the mirror part 32 to the electron gun part 31 becomes large.

FIG. 2 is a block diagram showing the configuration of the electron beam apparatus 101 according to the first embodiment of the present invention.
Although the case where the electron beam apparatus 101 is a scanning electron microscope equipped with a Schottky emission electron gun will be described, the electron beam apparatus and the electron gun may be of other types. For example, the electron beam apparatus includes a transmission electron microscope (TEM), a scanning electron microscope (SEM), and a scanning transmission electron microscope (STEM). You can also

  For example, in addition to Schottky-type electron guns, field-emission electron guns (FEG), hot cathode field-emission electron guns (thermally thermally assisted) ) A field-emission electron gun), a thermionic-emission electron gun, a cold cathode field emission electron gun (cold (cathode) field-emission electron gun), or the like may be used.

  The electron beam apparatus 101 includes an electron gun unit 31 that generates a primary electron beam 3 in which the internal space is maintained in an ultrahigh vacuum, and is generated in the electron gun unit 31 in which the internal space is maintained at a lower degree of vacuum than the electron gun unit 31. The mirror part 32 that scans the sample 12 with an electron probe that focuses the primary electron beam 3 on the sample 12 communicates with the internal space of the electron gun part 31 and the mirror part 32, and the primary electron beam 3 And a control unit 40 for controlling each part in the electron beam apparatus 101.

  In the electron beam apparatus 101, the primary electron beam 3 is emitted by the extraction voltage V1 applied between the cathode 1 and the first anode 2, and further accelerated to the acceleration voltage Vacc applied to the second anode 4, Proceed to the latter electromagnetic lens system. The suppressor electrode 5 is an electrode for suppressing unnecessary thermoelectrons emitted by flowing a heating current If through the filament holding the cathode 1, and a negative suppressor voltage Vs is applied thereto. The high voltage control circuit 21 has a function of generating an acceleration voltage Vacc, an extraction voltage V1, and a suppressor voltage Vs under the control of the computer 28.

  The first converging lens 6 once converges the primary electron beam 3 based on the control of the first converging lens control circuit 22. The primary electron beam 3 diverges again after convergence. The objective aperture 7 limits the irradiation angle of the primary electron beam 3. The second converging lens 8 converges the diverged primary electron beam 3 again based on the control of the second converging lens control circuit 23. Based on the control of the objective lens control circuit 25, the objective lens 11 narrows the primary electron beam 3 to be an electron probe. Further, the upper deflection coil 9 and the lower deflection coil 10 constituting the two-stage deflection coil deflect the electron probe and scan the sample 12 based on the control of the magnification control circuit 24.

  Here, the sample 12 is placed on the sample fine movement device 13 controlled by the sample fine movement control circuit 27. Of the signals generated from the irradiation point of the primary electron beam 3 of the sample 12, the reflected electron signal 14 having a high energy emitted at a relatively shallow angle is detected by the detector 17 and amplified by the amplifier 18. Further, the secondary electron signal 15 having a low energy is wound up by the magnetic field of the objective lens 11 and detected by the orthogonal electromagnetic field (EXB) device 16 disposed on the upper side of the objective lens 11 without causing an axis shift in the primary electron beam 3. The signal is detected by the amplifier 19 and amplified by the amplifier 20. Output signals (detection signals) from the amplifiers 18 and 20 are input to the signal control circuit 26.

  The computer 28 controls the high voltage control circuit 21, the first convergent lens control circuit 22, the second convergent lens control circuit 23, the magnification control circuit 24, the objective lens control circuit 25, the signal control circuit 26, and the sample fine movement control circuit 27. At the same time, the amplified secondary electron and reflected electron signals are processed and displayed on the screen of the display device 29 as an enlarged image of the sample 12.

  Mode settings such as “observation mode” and “analysis mode” described above can be selected or set in the computer 28 via the input device 30. Then, based on the control of the computer 28, the current of the first convergent lens 6 for the selected mode is set by the first convergent lens control circuit 22, the crossover point is controlled, and the target probe current Ip is set. .

  As described above, the differential exhaust diaphragm 33 is disposed between the electron gun unit 31 and the mirror unit 32. Further, a diaphragm mechanism 34 having a plurality of different aperture diameters (for example, a diameter of 0.5 [mm] and a diameter of 0.1 [mm]) is provided between the second anode 4 and the first converging lens 6. The maximum value of the probe current Ip of the primary electron beam 3 traveling in the direction of the first convergent lens is determined by this diaphragm.

FIG. 3 is a partial optical path explanatory diagram showing the relationship between the crossover position b1 and the probe current Ip.
Here, it is assumed that the distance from the principal point of the first focusing lens 6 to the crossover point is the crossover position b1, the probe current is Ip, and the beam spread on the differential exhaust diaphragm 33 is ds.

  From the opening half angle αg of the primary electron beam 3 given when the aperture of the objective aperture 7 is projected onto the aperture surface of the aperture mechanism 34 by the first converging lens 6, the probe current Ip passing through the projection diameter is given by Given. Here, αgmax is a beam opening angle at which the maximum probe current Ipmax is obtained, and depends on the aperture diameter of the aperture mechanism 34. The case where the maximum probe current Ipmax is based on 100 [nA] is exemplified, but the value of the maximum probe current Ipmax may be increased or decreased.

  Further, the aperture diameter dca of the aperture mechanism 34, the distance Lca between the principal point of the first focusing lens 6 and the aperture surface of the aperture mechanism 34, and the distance a1 between the cathode 1 and the first focusing lens 6, the beam opening angle αgmax is Is given by:

  Here, when the aperture diameter dca, distance Lca, and distance a1 of the diaphragm mechanism 34 are changed, the maximum probe current Ipmax is changed. Therefore, when it is assumed that 100 [nA] is obtained as the reference maximum probe current Ipmax, it is necessary to recalculate the maximum probe current Ipmax by comparing the aperture diameter dca, the distance Lca, and the distance a1 after the dimension change. . A beam opening angle αg1 obtained by limiting the beam opening angle αg with the objective aperture 7 is given by the following equation. M1 is a reduction ratio of the first converging lens 6, ra is an aperture radius of the objective aperture 7, and L1 is a distance between the first converging lens 6 and the objective aperture 7.

  αg is the condition of each crossover position b1 and the beam opening angle αgmax not limited by the objective aperture 7 is compared with the beam opening angle αg1 limited by the objective aperture 7, and the smaller condition is selected. That is, when min (X, Y) is an operator that selects the smaller of X and Y, an effective beam opening angle αg is given by the following equation.

  Using this beam opening angle αg, the relationship between the crossover position b1 and the probe current Ip is obtained from the equation (1).

  Here, the beam diameter ds on the differential exhaust diaphragm 33 is given by the following expression from the distance Ls between the first converging lens 6 and the differential exhaust diaphragm 33.

4A is a graph showing a change in the probe current Ip with respect to the crossover position b1 of the first converging lens 6. FIG. 4B is a graph on the opening surface of the differential exhaust diaphragm 33 with respect to the crossover position b1. It is a graph which shows the change of the breadth of the beam in.
The aperture mechanism 34 has apertures with aperture diameters of 0.5 [mm] and 0.1 [mm], and other conditions were as follows.

Ipmax 100 [nA]
a1 40 [mm]
b1 10-150 [mm]
ra 0.025 [mm]
L1 150 [mm]
dca 0.5 [mm]
Lca 20 [mm]
Ls 100 [mm]

  As shown in FIG. 4A, when the probe current Ip is changed from 0.001 [nA] (1 [pA]) to 100 [nA], the opening diameter of the differential exhaust throttle 33 is 0.5 [ In the case of [mm], it was realized by changing the crossover position b1 from 10 [mm] to 145 [mm]. However, when the opening diameter of the differential exhaust throttle 33 is 0.1 [mm] Was 4 [nA] when the crossover position b1 was 120 [mm], and a probe current Ip of more than that could not be obtained.

  On the other hand, when the opening diameter of the differential exhaust diaphragm 33 is 0.5 [mm], in order to prevent the differential exhaust diaphragm 33 itself from being irradiated with the beam, the beam spread ds is set to 0.5 [mm]. Must be: At this time, as shown in FIG. 4B, when the aperture diameter of the aperture mechanism 34 is 0.5 [mm], it is necessary to set the crossover position b1 to 70 [mm] or more. Is 0.1 [mm], it is necessary to set the crossover position b1 to 30 [mm] or more.

  Therefore, when obtaining a small probe current Ip for the “observation mode” described above, the crossover position b1 is set in the range of 30 [mm] to 120 [mm], and the aperture diameter of the diaphragm mechanism 34 is set to 0.1. Select [mm]. When obtaining a large probe current Ip for the “analysis mode”, the crossover position b1 is set in the range of 70 [mm] to 145 [mm], and the aperture diameter of the diaphragm mechanism 34 is 0.5 [mm]. In this case, a probe current Ip having a wide dynamic range from 20 [pA] to 100 [nA] can be obtained without irradiating the differential exhaust diaphragm 33 with a beam and contaminating it. Although the case where there are two probe current setting modes has been described, the probe current setting mode may be three or more.

FIG. 5 is a screen diagram illustrating an example of a warning display displayed on the display device 29.
When the operator operates the input device 30 and selects a mode such as “observation mode” or “analysis mode”, the electron beam apparatus 101 controls the operator as shown in FIG. A warning window (dialog box) 61 that prompts the diaphragm mechanism 34 to select an aperture with an appropriate aperture diameter may be displayed on the display device 29.

  In this case, the operator operates the input device 30 (including a pointing device) after confirming that the aperture diameter of the aperture mechanism 34 is appropriately selected, and displays it on the screen of the display device 29. The pointer 62 is moved and the confirmation button 63 is pressed. Then, the computer 28 waits for the confirmation button 63 to be pressed and executes the next process. For this reason, the operator does not forget to change the setting of the aperture mechanism 34, and the aperture mechanism 34 selects an aperture with an appropriate aperture diameter according to the mode selected with certainty.

  FIG. 6 is a configuration block diagram showing an electron beam apparatus 102 according to the second embodiment of the present invention. The electron beam apparatus 102 according to the second embodiment may have the same configuration as the electron beam apparatus 101 according to the first embodiment, except that the aperture diameter reading mechanism 35 attached to the aperture mechanism 34 is provided. The aperture diameter reading mechanism 35 has a function of reading aperture information indicating an aperture diameter of the aperture selected by the aperture mechanism 34 or a setting number for identifying the selected aperture. The aperture diameter reading mechanism 35 transfers the read aperture information to the computer 28 connected thereto. Then, the computer 28 selects an appropriate probe current setting mode according to the aperture diameter or setting number of the aperture set in the aperture mechanism 34. Thus, the current of the first converging lens 6 is set by the first converging lens control circuit 22 within a range in which the differential exhaust diaphragm 33 is not contaminated.

  According to this electron beam apparatus 102, even if an operator inadvertently switches the aperture of the aperture mechanism 34 to one with a different aperture diameter, the aperture diameter reading mechanism 35 reads the aperture diameter of the selected aperture and the like. By selecting the probe current mode corresponding to the read aperture diameter, the probe current mode setting that contaminates the differential exhaust diaphragm 33 can be automatically avoided.

  FIG. 7 is a block diagram showing the configuration of the electron beam apparatus 103 according to the third embodiment of the present invention. The electron beam apparatus 103 according to the third embodiment includes a drive mechanism 36 mechanically or electrically connected to the aperture mechanism 34 and a drive mechanism control circuit 37 connected to the drive mechanism 36 and controlled by a computer 28. Except for this, the configuration may be the same as that of the electron beam apparatus 101 of the first embodiment.

  When the operator changes the probe current setting mode, the fact that the setting has been changed is transferred to the computer 28. Then, the drive mechanism 36 is operated by the drive mechanism control circuit 37 so that the aperture diameter of the aperture mechanism 34 is set appropriately for the changed probe current mode, and the aperture diameter of the aperture is automatically set. Can be switched.

  According to the electron beam apparatus 103, even when the probe current mode is changed, the use of the aperture diameter of the diaphragm mechanism 34 that contaminates the differential exhaust diaphragm 33 is avoided, and the diaphragm mechanism 34 always corresponding to the probe current mode. The opening diameter can be set.

  Thus, according to the electron beam apparatuses 101 to 103 of the present embodiment, the first converging lens includes the diaphragm mechanism 34 having a plurality of diaphragms having different aperture diameters between the cathode 1 and the first converging lens 6. Corresponding to the convergence position (crossover point) of the primary electron beam by No. 6, the aperture diameter of the aperture of the aperture mechanism 34 can be selected and used. For this reason, the spread of the primary electron beam 3 on the differential exhaust diaphragm 33 is suppressed, and it is used for various observations and analyzes while preventing the diaphragm aperture from being contaminated, which causes the functional degradation of the electron beam apparatuses 101 to 103. A probe current Ip having a wide dynamic range can be obtained.

DESCRIPTION OF SYMBOLS 1 Cathode 2 1st anode 3 Primary electron beam 4 2nd anode 5 Suppressor electrode 6 1st converging lens 7 Objective diaphragm 8 2nd converging lens 9 Upper stage deflection coil 10 Lower stage deflection coil 11 Objective lens 12 Sample 13 Sample fine movement apparatus 14 Reflected electron Signal 15 Secondary Electron Signal 16 Orthogonal Electromagnetic Field (EXB) Device 17, 19 Detector 18, 20 Amplifier 21 High Voltage Control Circuit 22 First Convergence Lens Control Circuit 23 Second Convergence Lens Control Circuit 24 Magnification Control Circuit 25 Objective Lens Control Circuit 26 Signal control circuit 27 Sample fine movement control circuit 28 Computer 29 Display device 30 Input device 31 Electron gun section 32 Mirror body 33 Differential exhaust diaphragm 34 Diaphragm mechanism 35 Aperture diameter reading mechanism 36 Drive mechanism 37 Drive mechanism control circuit 40 Control section 51 Electron source 55 Converging lens 56 Crossover point 62 Pointer 3 confirmation button 101,102,103,105 electron beam apparatus

Claims (4)

An electron gun section containing an electron gun that generates a primary electron beam;
A mirror body portion containing an objective lens for focusing the primary electron beam to form an electron probe;
A differential exhaust throttle for communicating the electron gun part and the mirror part;
A converging lens provided in the electron gun unit and forming the crossover point on or near the opening surface of the differential exhaust diaphragm by converging the primary electron beam;
An aperture mechanism that is arranged in the optical path from the electron gun to the converging lens and that can switch an aperture diameter;
A switching mechanism for switching the opening diameter of the aperture mechanism;
A computer connected to the input device and the display device for controlling at least the convergent lens;
With
The computer sets the position of the crossover point within a predetermined range according to the mode of operation selected via the input device, and the primary electron beam opens the opening of the differential exhaust throttle. The display device has a display that prompts the user to select an aperture diameter of the aperture mechanism that can limit the spread of the primary electron beam to a size that does not irradiate the peripheral portion of the aperture. An electron beam device. The electron beam apparatus according to claim 1,
An electron beam apparatus comprising an aperture diameter reading mechanism for reading an aperture diameter of the aperture mechanism. The electron beam apparatus according to claim 2,
The beam current value of the primary electron beam at the crossover point or the control current value of the converging lens is set within a range in which the differential exhaust diaphragm is not contaminated according to the aperture diameter read by the aperture diameter reading mechanism. An electron beam apparatus comprising a computer for setting. The electron beam apparatus according to claim 3,
An electron beam apparatus comprising: a converging lens control circuit that controls the converging lens according to a value set by the computer.

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