JP4209434B2 - Charged particle beam equipment - Google Patents

Description

  The present invention relates to a charged particle beam apparatus, and more particularly to a charged particle beam apparatus such as a scanning electron microscope of a type that adjusts contrast and / or brightness by operating a pointing device such as a mouse.

  In a scanning electron microscope, one of the charged particle beam devices, in order to improve the image quality of the sample image, focus adjustment to make the electron beam the finest on the sample, astigmatism correction to correct astigmatism Adjustment, adjustment of image contrast (brightness ratio), brightness (brightness), etc., setting of magnification, and various other adjustments are required. These adjustments were normally performed using an operation panel equipped with switches, rotary knobs, etc., but in recent years, a personal computer is a component, and as with general computer application software, a graphical user interface function is provided. It has come to do using. In this method, a pointing device such as a mouse is used to operate buttons, slide bars, and the like displayed on the screen, and the operations are converted into electrical signals to control the apparatus. An example of a scanning electron microscope using such a graphical user interface function is described in Patent Document 1.

JP-A-8-287860

  In the prior art, when a plurality of detectors are provided, it is not considered in terms of operability for adjusting contrast and brightness when observing while switching images generated from signals detected by a plurality of detectors. It was necessary to readjust the contrast and brightness each time the instrument was switched.

  As an example, a scanning electron microscope provided with a secondary electron detector and a backscattered electron detector will be described. The backscattered electron detector has a detection sensitivity lower than that of the secondary electron detector and is difficult to recognize as an image unless it is in focus, but has an advantage that the information on the sample surface can be detected in detail. On the other hand, the secondary electron detector has an advantage that it has a higher detection sensitivity than the backscattered electron detector and can be recognized as an image even when it is not in focus, and is used for visual field movement and focusing.

  FIG. 12 shows an operation flow of conventional sample observation utilizing such advantages. First, a secondary electron detector is selected (S121), and a secondary electron image of the sample is displayed on the image display. Next, sample movement (field movement), magnification adjustment (S122), and adjustment of brightness, contrast, focus, and the like (S123) are performed. It is determined whether or not the desired visual field has been selected (S124). If “No”, the process returns to the original and the same steps are repeated. In general, several adjustments occur to adjust from a low magnification to a high magnification before setting the observation field of view.

When the setting of the observation visual field is completed, that is, if the determination result of whether or not the desired visual field is selected is “Yes”, the reflected electron detector is selected so as to display the reflected electron image of the sample (S125). When the detector is switched, it is necessary to adjust the brightness and contrast again due to the difference in the sensitivity of the detector (S126). When appropriate brightness and contrast are obtained, observation and photography are performed (S127). When the operation in one observation field of view is completed, it is determined whether or not to move to the next observation field (S128). If the result is “Yes”, the same steps are repeated. Exit to become.

  In such operations, contrast and brightness change due to the difference in detector sensitivity when switching detectors, and it is necessary to adjust the contrast and brightness again. There is a problem that it is troublesome.

  An object of the present invention is to provide a charged particle beam apparatus that has excellent operability without readjustment of contrast and / or brightness at the time of switching of detection systems, and is easy to understand the relationship between images based on signals generated by a plurality of detection systems. It is to provide.

The present invention provides a charged particle beam source that emits a charged particle beam, a scanner that scans a sample with the charged particle beam, and a plurality of signals that characterize the sample by detecting information obtained from the sample by the scanning. a plurality of detection systems for generating separately Computing a pointing device - a motor, and a signal selector, the computer - and the image display device which is controlled by the motor, in response to an operation of the pointing device, the Selecting an arbitrary detection system from a plurality of detection systems and controlling the signal selector to display an image of the sample on the image display based on a signal generated by the selected detection system; the computer - and a control means controlled by the motor, the image indicator own for said selected detection system generated signal in addition to the image of the signal generated by the selected detection system Display and automatic adjustment button for adjusting button and the selected signals generated by the detection system other than the detection system of the plurality of detection systems, the control means, the automatic by operating the pointing device when you select one or more automatic adjustment button of the adjustment buttons, and contrast and / or brightness of the signal generated by the selection has been detected system is the selection of the plurality of detection systems characterized in that automatically adjusts the contrast and / or brightness of the signals generated by the detection system other than the detection system so as to coincide with the target value.

In the present invention , a charged particle beam source that emits a charged particle beam, a scanner that scans a sample with the charged particle beam, and a plurality of features that characterize the sample by detecting information obtained from the sample by the scanning. a plurality of detection systems for generating a signal separately computing a pointing device - a motor, and a signal selector, and a combiner for generating a composite signal of the plurality of the signals generated by the detection system, said plurality detection system with the generated signal and separate display before Symbol computer that displays a region of the image display device an image of the sample based on the combined signal - and the image display device which is controlled by the motor, which is the display more for signals prior SL pointing device number in response to the operation of the chair separately from the contrast and / or pre-SL computer you adjust the brightness - to include a control means which is controlled by the motor Can Ru.

In one aspect of the present invention, a charged particle beam source that emits a charged particle beam, a scanner that scans a sample with the charged particle beam, and information obtained from the sample by the scanning is detected to detect the sample. a plurality of detection systems for generating a plurality of signals are separately characterizing Computing a pointing device - a motor, and a signal selector, the computer - and the image display device which is controlled by the motor, the operation of the pointing device In response, the signal selection is performed such that an arbitrary detection system of the plurality of detection systems is selected and an image of the sample based on a signal generated by the selected detection system is displayed on the image display. And controlling the contrast and / or brightness of the signal generated by the selected detection system and the selected detection system other than the selected detection system. The contrast of the signal generated by the output system and / or brightness and the previous SL computer you adjusted in conjunction with each - can and a control means controlled by the motor.

Furthermore, in another aspect of the present invention, a charged particle beam source that emits a charged particle beam, a scanner that scans a sample with the charged particle beam, and information obtained from the sample by the scanning are detected and the a plurality of detection systems for generating a plurality of signals characterizing a sample separately Computing a pointing device - a motor, and a signal selector, the computer - and the image display device which is controlled by the motor, of the pointing device In response to the operation, at least two detection systems of the plurality of detection systems are selected, and images of the sample based on signals generated by the selected detection systems are displayed on the image display as separate display areas. the controls the signal selector to display, contrast and / or pre-Symbol Con tO aDJUST in conjunction with brightness of the signals generated by the plurality of detection systems Interview - can and a control means controlled by the motor.

  According to the present invention, there is provided a charged particle beam device that has excellent operability that does not readjust contrast and / or brightness when switching between detection systems, and that allows easy understanding of image relationships based on signals generated by a plurality of detection systems. Provided.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to specific examples.

  FIG. 1 schematically shows an overall configuration of a charged particle beam apparatus according to the present invention, and is an example in which a scanning electron microscope is used as a charged particle beam apparatus. A scanning electron microscope main body (mirror part) 1 includes an electron source 2, a first converging lens 5, an astigmatism correction coil 6, a deflection coil 7, a second converging lens 8, a secondary electron detector 9, and reflected electrons. A detector 10, a scanning electron microscope control device 12 and the like are included. Here, an example including two detectors in which a secondary electron detector is used as a first detector and a backscattered electron detector is used as a second detector is shown. An X-ray detector or a fluorescence detector is shown. Or a plurality of detectors of the same type may be provided. Furthermore, although two examples are shown, the number may be larger.

  The scanning electron microscope control device 12 includes an electron beam control unit 13, a first amplifier 15, a second amplifier 16, a switch 17, an image memory 18, and system control means 14 for controlling each component. Further, a computer 19 including a keyboard 20 as a character input device, a mouse 21 as a pointing device, and an image display 22 such as a cathode ray tube is provided.

  The electron beam 3 emitted from the electron gun 2 passes through the electron beam aperture 4 and is converged on the sample 11 by the first focusing lens 5 and the second focusing lens 8, and the sample 11 is converged by using the deflection coil 7. The electron beam 3 is scanned two-dimensionally. Further, the astigmatism of the electron beam 3 is corrected by using the astigmatism correction coil 6. Those control of the electron beam 3 is performed by the system control means 14 of the scanning electron microscope control device 12 controlling the electron beam control unit 13 constituted by a high voltage power source, a lens power source, a deflection amplifier and the like. When the sample 11 is irradiated with the electron beam 3, secondary electrons are generated from the sample 11. The secondary electron detector 9 detects the secondary electrons and converts them into electric signals. When the sample 11 is irradiated with the electron beam 3, reflected electrons are generated from the sample 11. The reflected electron detector 10 detects this reflected electron and converts it into an electrical signal.

  The first amplifier 15 and the second amplifier 16 amplify and add a bias to the signals generated by the connected secondary electron detector 9 and the reflected electron detector 10. In this case, the amplification degree (gain) and the bias value are proportional to the contrast and brightness when the image is generated. The switch 17 selects one of the two detectors and outputs it to the image memory 18. The image memory 18 includes an A / D converter that converts an analog signal into digital data, a memory that stores image data, and the like, and generates image data from an output signal of a detector that is input in synchronization with a scanning signal. The computer 19 displays the image data transferred from the image memory 18 on the image display 22. Further, the computer 19 displays an operation screen on the image display 22 and gives operation signals of the keyboard 20 and the mouse 21 to the system control means 14. The system control means 14 controls each component according to the operation signal.

  In the scanning electron microscope having such a configuration, after the visual field movement and focusing adjustment of the sample 11 are performed using the signal of the secondary electron detector 9, the surface of the sample 11 is detected using the signal of the reflected electron detector 10. The operation at the time of observation will be described below. First, the operation screen displayed on the image display 22 is operated according to a predetermined procedure using the keyboard 20 and the mouse 21, and the sample 11 is irradiated with the electron beam 3 and scanned. Next, an image is displayed on the image display 22 and the contrast and brightness are adjusted.

  FIG. 2 shows a first example of the operation screen in the first embodiment. The image display area 30 is displayed on the image display 22, the switch 31 selects a signal to be displayed there, the slide bar 32 for adjusting the contrast, and the brightness. A slide bar 33 and a mouse cursor 35 to be adjusted are displayed. Although omitted in this figure, a slide bar for adjusting the focus and astigmatism correction is also displayed.

  When secondary electrons are selected from the pop-up menu of the signal selection switch 31, the computer 19 gives an operation signal to the system control means 14. The system control means 14 switches the switch 17 so as to give the signal of the secondary electron detector 9 to the image memory 18, and the image memory 18 generates image data of the secondary electron image. Further, the image data is transferred to the computer 19, and the computer 19 displays the secondary electron image in the image display area 30 of the image display 22. The contrast of the secondary electron image to be displayed is adjusted with the slide bar 32 displayed on the image display 22. That is, by operating the mouse 21, the mouse cursor 35 is moved onto the knob of the slide bar 32, and the knob of the slide bar 32 is moved by performing an operation of dragging the mouse while keeping the mouse button pressed. The computer 19 gives an operation signal according to the operation operation to the system control means 14. The system control means 14 links the amplification degree of the amplifier 15 that amplifies the signal of the secondary electron detector 9 that is selected for display and the amplification degree of the amplifier 16 that amplifies the signal of the reflected electron detector 10 that is not selected and displayed. Change. When the degree of amplification changes and the amplitude of the signal changes, the contrast changes. Similarly, in adjusting brightness, the bias value of the amplifier 15 of the secondary electron detector 9 selected and displayed by operating the slide bar 33 and the bias value of the amplifier 16 that amplifies the signal of the reflected electron detector 10 not selected and displayed are displayed. Change in conjunction with. When the bias value changes and the signal bias changes, the brightness changes. After adjusting the contrast and brightness of the image in this way, the alignment and focus adjustment to be observed with the secondary electron image are adjusted.

  Next, the signal selection switch 31 on the operation screen is switched from secondary electrons to reflected electrons. Since the amplification degree and bias value of the amplifier 16 are adjusted in conjunction with those of the amplifier 15, the computer 19 switches the secondary electrons to the reflected electrons and simultaneously displays the secondary electron image. The reflected electron image of the sample 11 is displayed on the image display 22 with the same contrast and brightness.

  In this way, since it is not necessary to readjust the contrast and brightness every time the detector is switched, the troublesomeness of the operation is eliminated, and it is not necessary to have a slide bar for each individual detector. Simplification is achieved and effective use of the display area of the image display 22 is achieved.

  The contrast may be adjusted by moving the mouse cursor 35 in the image display area 30 and moving the mouse 21 left and right while pressing the left button of the mouse 21, and the brightness may be adjusted by moving the mouse cursor left and right while pressing the right button. In this way, it is not necessary to display a slide bar for adjusting contrast and brightness, and the display area of the display 22 can be used more effectively.

  FIG. 3 shows a second example of the operation screen according to the first embodiment. Two image display areas 30a and 30b are displayed as image display areas for displaying signals from two detectors. It has. In addition, in order to select a signal to be displayed in each image display area, a first signal selection switch 31a and a second signal selection switch 31b are provided. Here, the signal of the secondary electron detector and the signal of the backscattered electron detector are selected.

Further, the contrast can be adjusted by moving the mouse cursor 35 into the image display area as described in the first embodiment and moving it to the left and right while pressing the left button of the mouse 21. You can also adjust the brightness by moving left and right while pressing the right button. When this operation is performed in the image display area 31a, the amplification degree and the bias value of the amplifier 15 that amplifies the signal of the secondary electron detector 9 selected for display in the image display area 31a are controlled, when operated in the image display region 3 in 0b may control the amplification degree and the bias value of the amplifier 16 which amplifies the signal of the reflected detector 10 that displays the selection of the image display area 30b.

  In this example, it is possible to adjust the amplification degree and the bias value while dragging the button of the mouse 21 in any of the image display areas 31a and 31b. In this case, the amplifiers connected to the respective detectors. The amplification degree and the bias value are adjusted in conjunction with each other. Therefore, also in this example, the same effect as described in relation to the first example of the operation screen can be expected.

  FIG. 4 is a block diagram showing the configuration of the main part of the charged particle beam apparatus according to the present invention. The difference between the present embodiment and that shown in FIG. 1 is automatic adjustment means for automatically adjusting contrast and / or brightness. 23. This embodiment is also an example in which a scanning electron microscope is used as a charged particle beam apparatus. The mirror part not shown is the same as the embodiment shown in FIG.

In the present embodiment provided with this automatic adjustment means 23 , as in the operation example shown in FIG. 5, the contrast is automatically adjusted while an image of one frame of the amplifier that amplifies the signal from the detector is obtained. , The amplification degree of the amplifier is adjusted so that the maximum value thereof matches the target value set in the control means 14, and the signal from the detector is used as the automatic brightness adjustment. The output signal of the amplifier to be amplified is measured while an image of one frame is obtained, and the bias value of the amplifier is adjusted so that the average value becomes the target value set in the control means 14. When both the amplification degree and the bias value match the target value, the automatic adjustment ends.

  FIG. 6 shows a configuration example of the automatic adjustment means 23 of FIG. This comprises maximum value detection circuits 41 and 43, average value detection circuits 42 and 44, a switch 45 for selecting a detection signal, and an A / D converter 46. The control means 14 converts the values detected by the maximum value detection circuits 41 and 43 and the average value detection circuits 42 and 44 into digital values by the A / D converter 46 while switching the switch 45 so as to match the read target value. The amplification degree and bias value of 15 and 16 are set.

  FIG. 7 is a diagram showing an example of an operation screen provided with the automatic adjustment means 23. In addition to the slide bars 32 and 33 described in FIG. 1, the display selection signal automatic adjustment for automatically adjusting the display selected signal is performed. A button 36 and a display unselected signal automatic adjustment button 37 for automatically adjusting a signal that is not selected for display are provided. However, the slide bars 32 and 33 are not shown. When the mouse cursor 35 is moved on the display selection signal automatic adjustment button 36 and the button of the mouse 21 is clicked, one automatic adjustment is executed. Therefore, each time the viewing field is changed, a button click is necessary. When the mouse button is double-clicked, automatic adjustment is continuously performed even when the observation field of view is changed. The display non-selected signal automatic adjustment button 37 for a signal that is not selected for display also performs the same processing.

  In such a configuration, after the observation field is selected or focused using the signal of the secondary electron detector 9, the surface of the sample 11 is observed using the signal of the reflected electron detector 10. By setting both the display selection signal automatic adjustment button 36 and the display unselected signal automatic adjustment button 37 that are selected for display on the operation screen to be set to continuous automatic adjustment, there is no need for manual contrast and brightness adjustment. Is simplified. Even when the display selection is switched, the signals of the detectors not selected for display are automatically adjusted, so that the image becomes easy to see from the moment of switching.

  FIG. 8 shows the operation flow of the sample observation described above in the example provided with the automatic adjustment means 23. First, the secondary electron detector 9 is selected (S81), and a secondary electron image is displayed on the image display 22. Next, sample movement (field selection) and magnification adjustment are performed (S82), and brightness and contrast are further adjusted (S83). Focus adjustment should also be performed at this stage. Thereafter, it is determined whether or not the desired viewing field is obtained. If the result is “No”, the process returns to step S82. In practice, several adjustments are usually required to adjust from a low magnification to a high magnification before setting the observation field of view. That is, steps S82 to S84 are repeated several times. When the setting of the observation visual field is completed, that is, if the result of step S84 is “Yes”, the reflected electron detector 10 is selected to display the reflected electron image (S85). Even if the detector is switched, it is not necessary to adjust the brightness and contrast again, and observation and photography can be performed as they are.

  However, the automatic adjustment algorithm described above may not be able to adjust to the optimum contrast and brightness depending on the sample and composition to be observed. In such a case, it is possible to cancel the automatic adjustment with the automatic adjustment button 36 and the automatic adjustment button 37 and perform manual adjustment.

For signals that are selected for display, set the automatic adjustment to be canceled and manually adjusted, and for signals that are not selected for display, the automatic adjustment target value is displayed. Control is performed so that the set value after adjustment of the selected signal is obtained. That is, when the secondary electron detector 9 is selected for display and the reflected electron detector 10 is not selected for display, the automatic adjustment means 23 is an image of one frame of the amplifier 15 that amplifies the signal of the secondary electron detector 9. The output signal is measured while obtaining the maximum amplitude value and the minimum amplitude value. Further, the output signal of the amplifier 16 that amplifies the signal of the backscattered electron detector 10 is measured while an image of one frame is obtained, and the maximum and minimum amplitude values are obtained from the signal of the secondary electron detector 9. The amplifier 16 operates to adjust the amplification degree so as to match the obtained value. Thereby, even if the display signal is switched from the secondary electrons to the reflected electrons, the contrast of the reflected electron image becomes the same as the contrast of the manually adjusted secondary electron image, and there is no need to readjust. Brightness can be adjusted in exactly the same way.
(Reference example )

FIG. 9 is a block diagram showing the configuration of the main part of a charged particle beam apparatus having a signal synthesizer for synthesizing signals from a plurality of detectors. This reference example is also used as a charged particle beam apparatus by a scanning electron microscope. This is an example. The mirror part not shown is the same as the embodiment shown in FIG.

  FIG. 10 is a circuit diagram of the signal synthesis unit of FIG. As shown in FIG. 10, the signal synthesis unit 24 includes a controllable volume 51 and an amplifier 52. The controllable volume 51 is generally constituted by an A / D converter or the like. A signal obtained by synthesizing the signal of the secondary electron detector 9 amplified by the amplifier 15 and the signal of the reflected electron detector amplified by the amplifier 16 is supplied to the image memory 18 through the switch 17. The composite ratio X is the ratio of the overall resistance R0 of the volume 51 and the resistance R1 connected to the output of the amplifier 15, and is given from the system control means 14. From the configuration of the volume 51 and the amplifier 52, the output V0 is obtained by V0 = X (V2−V1) + V1. Of course, the output of each of the amplifiers 15 and 16 is the sum of the product of the input value and the amplification factor and the bias value.

FIG. 11 is an example of an operation screen in this reference example. As image display areas for displaying signals from a plurality of detectors, a first image display area 30a, a second image display area 30b, and a third image display area 30c. It has three. Although three image display areas are shown here, it may be larger. Further, in order to select a signal to be displayed in each image display area, a first signal selection switch 31a, a second signal selection switch 31b, and a third signal selection switch 31c are provided. Here, a signal from the secondary electron detector 9, a signal from the backscattered electron detector 10, and a signal obtained by combining the two signals are selected. When the signal selection switches 31a and 31b are operated, the contrast is obtained by moving the mouse cursor 35 into the image display area and moving the mouse 21 left and right while pressing the left button of the mouse 21 as described in the description of the first embodiment. Can be adjusted. You can also adjust the brightness by moving left and right while pressing the right button. When the signal selection switch is operated, the synthesis ratio can be adjusted by this operation. This makes it easy to understand the relationship between a plurality of signals.

  In this embodiment, an electron beam is used as the charged particle beam, but the present invention can also be applied to the case where an ion beam is used as the charged particle beam.

1 is an overall schematic configuration diagram of a charged particle beam apparatus of the present invention. The figure which shows the 1st example of the operation screen of the charged particle beam apparatus of this invention. The figure which shows the 2nd example of the operation screen of the charged particle beam apparatus of this invention. The figure which shows the structure of the principal part of the charged particle beam apparatus provided with the automatic adjustment means which adjusts contrast and / or brightness automatically of this invention in a block format. The operation principle explanatory drawing of the charged particle beam apparatus provided with the automatic adjustment means which adjusts the contrast and / or brightness of this invention automatically. The figure which shows the structural example of the automatic adjustment means of FIG. The figure which shows the example of the operation screen of the charged particle beam apparatus provided with the automatic adjustment means of this invention. The figure which shows the operation flow of the sample observation of the charged particle beam apparatus provided with the automatic adjustment means of this invention. The figure which shows the structure of the principal part of the charged particle beam apparatus provided with the signal synthetic | combination part which synthesize | combines the signal of the several detector of a reference example in a block format. FIG. 10 is a circuit diagram of a signal synthesis unit in FIG. 9. The figure which shows the operation screen of the charged particle beam apparatus provided with the signal synthetic | combination part which synthesize | combines the signal of the several detector of a reference example . The figure which shows the operation flow of the conventional sample observation.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Scanning electron microscope main body, 2 ... Electron source, 3 ... Electron beam, 4 ... Electron beam aperture, 5 ... 1st converging lens, 6 ... Astigmatism correction coil, 7 ... Deflection coil, 8 ... 2nd convergence Lens, 9 ... Secondary electron detector, 10 ... Backscattered electron detector, 11 ... Sample, 12 ... Scanning electron microscope control device, 13 ... Electron beam control unit, 14 ... System control means, 15 ... Amplifier, 16 ... Amplifier, DESCRIPTION OF SYMBOLS 17 ... Switch, 18 ... Image memory, 19 ... Computer, 20 ... Keyboard, 21 ... Mouse, 22 ... Image display, 23 ... Automatic adjustment means, 24 ... Signal composition means, 30 ... Image display area, 31 ... Signal selection switch 32 ... Contrast adjustment slide bar, 33 ... Brightness adjustment slide bar, 35 ... Mouse cursor, 36 ... Display selection signal automatic adjustment button, 37 ... Display unselected signal automatic adjustment button, 41, 43 ... Maximum value detection circuit, 42, 44 ... average value detection circuit, 45 ... switch, 46 ... A / D converter, 51 ... volume, 52 ... amplifier.

Claims (2)

A charged particle beam source that emits a charged particle beam, a scanner that scans the sample with the charged particle beam, and a plurality of signals that characterize the sample are generated separately by detecting information obtained from the sample by the scanning. a plurality of detection systems, computer a pointing device - a motor, and a signal selector, the computer - and the image display device which is controlled by the motor, in response to an operation of the pointing device, the plurality of detection systems any select detection system controls the signal selector to display an image of the sample based on the signal generated by the selected detection system on the image display unit, the computer of the - Control means controlled by a controller,
The image display device is a selected one of said plurality of detection systems with automatic adjustment button for the selected signals generated by the selected detection system in addition to the image of the signals generated by the detection system An automatic adjustment button for signals generated by detection systems other than the detection system
Wherein, when by operating the pointing device to select one or more automatic adjustment button of the automatic adjustment button, and contrast and / or brightness of the signal generated by the selected detection system characterized in that the automatically adjusted to match the target value and the contrast and / or brightness of the selected signals generated by the detection system other than the detection system of the plurality of detection systems Charged particle beam device. The automatic adjustment button not selected by the pointing device according to claim 1 is an automatic adjustment button corresponding to a signal that gives an image displayed on the image display, and the control means is selected by the pointing device. automatically the contrast and / or brightness of the signal corresponding to the automatic adjustment button on the image contrast obtained by manually adjust the signal giving an image displayed on the display and / or brightness and match so the A charged particle beam apparatus characterized by adjusting to

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