JP2000260381A - Processing device for scanning image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To display and print a detected signal as a color image with good gradation and in broad field of view, by scanning charged particles in plane by a focused beams on a sample and detecting a signal generating at that time. SOLUTION: An irradiation system 1 generates electron beams, focuses the electron beams with a focusing lens 2, and scans the electron beams on a sample 7 with a deflecting coil 3. Secondary electrons emitted at that time are detected by a secondary electron detector 19, and an analog image signal generated by amplifying the detected signal (image signal) with a signal amplifier 20 is converted to a digital image signal with an image taking device 21. An image converting means 36 converts a monochrome image signal to color image. When the sample 7 is scanned precisely, five points at the center and four corners are enlarged and displayed at a prescribed magnification, and are respectively focus-adjusted and non-point-adjusted, values at respective points are stored, gap between them is compensated, and therefore, a clear image high in resolution is always displayed even if whole or a part of the very precise image is extracted, enlarged, and displayed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning type image processing apparatus for color-printing and color-printing a high-definition image obtained by surface-scanning a sample by narrowing a beam such as a particle beam. is there.

[0002]

2. Description of the Related Art Conventionally, a surface is scanned while irradiating a sample with electrons or ions, which are finely squeezed fine particles, and secondary electrons and secondary ions generated at that time are detected, and the brightness is modulated on a CRT. An enlarged scanned image is displayed, an image on a cathode ray tube is photographed with a polaroid film, or an ordinary film is photographed and printed on photographic paper to observe the scanned image.

[0003]

However, in the conventional cathode ray tube, usually, only a rectangular image of at most about 500 to 1600 pixels cannot be displayed due to the lack of resolution of the cathode ray tube, and the size of the scanned image that can be displayed is as follows. It has a rectangular shape of at most 20 cm, and has a problem that the resolution is poor and it is difficult to observe clearly. Similarly, even if an image on a cathode ray tube is photographed with a film and then printed on photographic paper, there is a problem that a scanned image of very fine pixels cannot be recorded and observed because of the use of the cathode ray tube.

For this reason, instead of recording a scanned image with a scanning microscope via a display device such as a cathode ray tube, an image signal obtained from the scanning microscope or the like is directly converted into a color image for display and high definition. It is desired to print and observe in a wide field of view.

[0005] The present invention solves these problems,
The purpose is to detect a signal generated by scanning a sample with a beam, and display and print a signal of one thousand to several tens of thousands of pixels as a color image for observation.

[0006]

Means for solving the problem will be described with reference to FIG. Here, the charged particles will be described as an example.

In FIG. 1, an irradiation system 1 performs, for example, a plane scanning in a state in which charged particles (such as electron beams) are generated, focused, and irradiated on a sample 7 with a narrowed beam. , The objective lens 6, the secondary electron detector 19, and the like.

The deflecting coil 3 deflects the electron beam, which is irradiated onto the sample 7 while being narrowly focused, and scans the sample 7 in a plane. The sample 7 is a sample on which an electron beam is scanned in a plane to detect a signal generated at that time.

[0009] The secondary electron detector 19 detects secondary electrons emitted from the sample 7. The display device 28
A secondary electronic image or the like is displayed in color.

Next, the operation will be described. The sample 7 is irradiated with a particle beam generated from a particle beam source (not shown) constituting the irradiation system 1, such as an electron beam, which is narrowed down by an objective lens 6, and is deflected by a deflection coil 3. An electron beam is scanned in a plane on the sample 7, for example, secondary electrons generated from the sample 7 are detected by a secondary electron detector 19, converted into a color image, and displayed on a screen.

At this time, when the magnification or the number of scanning lines is changed and the sample 7 is scanned with an electron beam when it is found that there is a gap between the scanning lines, the electron beam is decomposed almost to the interval between the scanning lines. The focus is to make it fat.

Further, the magnification or the number of scanning lines is changed,
When scanning the sample 7 with an electron beam, when it is determined that the space between the scanning lines is empty, the electron beam is used to perform planar scanning on minute regions substantially at intervals between the scanning lines.

[0013] Further, a signal detected by performing planar scanning of a central portion and a plurality of peripheral portions of the predetermined region of the sample is displayed as an enlarged image on a screen, and the displayed central enlarged image is displayed. The focusing of the beam is performed for each of a plurality of enlarged images around the beam, and the focus of the beam is corrected based on the focused value.

Further, a plurality of sets of detectors for detecting signals generated when the electron beam is irradiated on the sample 7 are provided at positions 180 degrees symmetric with respect to the sample 7, and the detectors symmetric with 180 degrees are provided. A plurality of sets of difference signals of the detected signals are generated, and the difference signals are each integrated in the scanning direction to generate height information in each direction of the sample,
The focusing of the electron beam is performed based on the generated height information of the sample 7 in each direction.

A signal detected by performing planar scanning of a central portion and a plurality of peripheral portions of the predetermined region of the sample is displayed as an enlarged image on a screen, and the displayed central enlarged image is displayed. The astigmatism of the beam is performed for each of a plurality of peripheral enlarged images, and the astigmatism of the beam is corrected based on the astigmatized values.

[0016] Further, the gray scale of the detected signal corresponds to
A table in which color gradations are registered is provided, and a detected signal is converted into a color signal with reference to the table.

Further, when converting the detected signal into a color signal, a gradation of a color signal corresponding to the gradation of the detected signal is created based on the two specified colors. To convert.

Further, the detected signal is made of 8 bits or more.
Alternatively, a color signal in a color data format used by a printing apparatus when a color signal is used for printing and the number of color bits are set.

Therefore, it is possible to detect a signal generated by scanning the sample with the beam, to convert a signal of one thousand to several tens of thousands of pixels into a color image, to display and print with good gradation and a wide field of view, and to observe. .

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments and operations of the present invention will now be described in detail with reference to FIGS. Here, the embodiment will be described in detail below using an electron beam as a charged particle as an example.

FIG. 1 shows a system configuration diagram of the present invention.
In FIG. 1, an irradiation system 1 generates an electron beam as a charged particle, focuses the electron beam, finely squeezes it onto a sample 7, and irradiates the sample 7 with a plane scan. The irradiation system 1 includes 2 to 6 and the like. .

The focusing lens 2 focuses an electron beam generated from an electron gun (not shown) and accelerated. The deflecting coil 3 deflects the electron beam irradiated onto the sample 7 by narrowing it down to scan the plane.

The astigmatism correction coil 4 corrects the astigmatism of the electron beam. The fine shift coil 5 moves the electron beam in the horizontal direction.

The dynamic focus coil 8 focuses the electron beam so as to be a fine electron beam even when the electron beam irradiates a position deviating from the central visual field position on the sample 7.

The objective lens 6 irradiates the electron beam on the sample 7 by narrowing it down. The sample 7 is a sample to be scanned and displayed on a plane with an electron beam to detect a signal generated at that time, and to be displayed and printed as a color image.

The arbitrary step scan generator 11 generates a scanning signal (horizontal and vertical scanning signals) of an arbitrary step. The scanning generator 12 generates a low-accuracy (for example, 500 pixels × 500 pixels) scanning signal used for a normal scanning electron microscope or the like.

The scanning signal switching device 13 is for arbitrarily switching between a scanning signal of an arbitrary step (for example, one thousand to several tens of thousands of pixels) and a low-precision scanning signal in accordance with an external switching mode.

The magnification control circuit 14 outputs a signal of a specified magnification based on a low-precision scanning signal supplied from the scanning generator 12. The magnification control circuit 15 outputs a signal of a designated magnification based on the scanning signal supplied from the scanning signal switching device 13.

The magnification control switch 16 is provided with a magnification control circuit 1
4, 15 or the signal of the scanning signal switching device 13 is switched and selected and supplied to the deflection coil 3, and a scanning current or the like having a predetermined magnification is supplied to the deflection coil 3.

The dynamic astigmatism control circuit 17 supplies current to the astigmatism correction coil 4 to perform astigmatism correction.
The fine shift control circuit 51 supplies a current to the fine shift coil 5 to control the movement of the visual field.

The dynamic focus control circuit 18
A current is supplied to the dynamic focus coil 8, and the dynamic focus (electron beam is deflected from the center of the field of view on the sample 7 and becomes out of focus. The correction is performed by supplying the current synchronously).

The secondary electron detector 19 detects and amplifies secondary electrons emitted when the surface of the sample 7 is scanned with an electron beam. The signal amplifier 20 amplifies a signal (image signal) detected by the secondary electron detector 19.

The image capturing device 21 converts an analog signal (image signal) such as secondary electrons emitted from the sample 7 amplified by the signal amplifier 20 into a digital image signal (for example, all the signals on the sample 7). 16,000 × 1 scanning range
The sampling is performed in synchronization with the horizontal scanning signal and the vertical scanning signal so as to have 6,000 pixels, and the data is quantized into 12-bit data and converted to obtain an image signal.

The I / Os 23 to 27 include a CPU 29, an arbitrary step scan generator 11, a magnification control circuit 15, a dynamic astigmatism control circuit 17, and a fine shift control circuit 5.
1. An input / output circuit for transmitting and receiving signals to and from the dynamic focus control circuit 18, for example, a D / A for converting a digital signal from the CPU 29 into an analog signal.
It is used for controlling signals such as conversion.

The printer 30 is a high-definition color printer (plotter). The display device 28 has a low resolution (5
(00 to 1800 dots), and may be a color CRT, a color liquid crystal, a television of a general home appliance, or the like.

The CPU 29 performs various processes in accordance with a program. Here, the CPU 29 includes an image editing unit 35, an image conversion unit 36, and the like, which are operated by the program.

The image editing means 35 edits an image and displays it on the screen 33. Image conversion means 36
For example, a monochrome image signal is converted into a color image signal (for example, a monochrome image signal is converted into a color image signal without lowering the gradation).

Next, the configuration and operation of FIG. 1 will be sequentially described in detail with reference to FIGS. FIG. 2 shows an explanatory diagram (thinning-out scanning) of the present invention. This is because the scanning signals (H,
5A and 5B are a configuration diagram and an explanatory diagram when a scanning signal (H, V) at an arbitrary step is generated by thinning V).

FIG. 2A shows a circuit configuration diagram. FIG.
2A, the clock generation circuit 32 generates a clock for generating a scanning signal.

The gate circuit 33 includes a clock generation circuit 32
The clock is switched so as to be supplied to the counters 36 and 37, either from the clock signal supplied from the controller or the clock after the clock is thinned out via the thinning circuit 35.

The latch 34 holds the thinning value set by the CPU 29. The thinning circuit 35 supplies clocks after thinning the clock supplied from the gate circuit 33 to the counters 36 and 37 by the thinning value set in the latch 34. For example, a clock thinned out every eight pulses is supplied to the counters 36 and 37 to generate the scanning signals (H, V) shown in FIG. 2B.

The counters 36 and 37 generate digital scanning signals (H, V) based on the input clock. The D / A's 38 and 39 convert digital scanning signals (H, V) into analog scanning signals.

FIG. 2B schematically shows a scanning signal when no thinning is performed and a scanning signal when thinning is performed. FIG. 2B-1 shows an example of the scanning signals (H, V) when no thinning is performed. In this case, the horizontal direction (H)
16000 steps (pixels), 16 in the vertical direction (V)
It becomes a scanning signal (H, V) of 000 steps (pixels).

FIG. 2B-2 shows an example of the scanning signals (H, V) when thinning is performed (when thinning is performed every eight pulses). In this case, 2000 steps (pixels) in the horizontal direction (H) and 2000 steps (pixels) in the vertical direction (V)
(H, V).

As described above, under the configuration of FIG. 2A, the CPU 29 merely sets the thinning value in the latch 34 arbitrarily, and the scanning signals (H, H) having the number of steps corresponding to the thinning value are set. V) can be generated.

FIG. 3 is an explanatory diagram (arbitrary step variable scanning, part 1) of the present invention. This is because the CPU 29 arbitrarily outputs a scanning signal (H, V) of an arbitrary step, a shift signal for shifting (adding a DC component) the scanning signal (H, V), and an enlarged signal for enlarging the scanning signal (H, V). The scan signal (H, V) is set and an arbitrary step is generated.

In FIG. 3, the clock generation circuit 41
A clock is generated. The gate circuit 42 outputs the clock from the clock generation circuit 41 to the counters 43 and 4.
4 or to comparators 46 and 48.

The counters 43 and 44 count the clocks supplied from the clock generation circuit 41 via the gate circuit 42 and generate digital scanning signals (H, V).

The latches 45 and 47 are latches by which the CPU 29 sets an arbitrary number of steps of the scanning signal (H, V). The comparators 46 and 48 output the clock supplied from the clock generation circuit 41 via the gate circuit 42 to the latch 4.
The counting is performed until the number of steps becomes equal to the number of steps set in 6, 47, and when the number of steps becomes equal, re-counting is started from 0. As a result, digital scan signals (H, V) of the number of steps set in the latches 46, 47 are output from the outputs of the comparators 46, 48.

The latches 49 and 50 are used by the CPU 29 to set an arbitrary number of steps for shifting. Latch 5
Reference numerals 2 and 53 indicate that the CPU 29 sets an arbitrary number of steps for enlargement.

D / A 54 and 55 are counters 43 and 4
4, or converts digital scanning signals (H, V) from the comparators 46 and 48 into analog scanning signals (H, V) A.

The D / As 56 and 57 convert the digital shift values set in the latches 49 and 50 into analog shift values (H, V) B. D / A 58, 59
Converts the digital expansion value set in the latches 52 and 53 into an analog expansion value (H, V) C.

The shift circuits 60 and 61 include D / As 54 and 5
5 is added (A + B) to the scanning signal (H, V) A from D / A 56 and the shift value (H−V) B from D / A 56, 57.

The operation units 62 and 63 are provided with shift circuits 60 and 6
The scanning signal (A + B) and the enlarged value (H,
V) C and the following calculation shown in the figure is performed to generate, for example, enlarged small scanning signals (H, V) at a total of five points at the center and four corners.

Y = 10 (A + B) * C With the above circuit configuration, the CPU 29
By simply setting an arbitrary predetermined value to 7, 49, 50, 52, and 53, automatically generating, for example, an enlarged scanning signal (H, V) at the center of, for example, 16000 × 16000 pixels and four corners. Becomes possible.

FIG. 4 is an explanatory view (arbitrary step variable scanning, part 2) of the present invention. FIG. 4A shows an operation flowchart. In FIG. 4A, S1 transfers the number of steps (H, V) to the latch. That is, the CPU 29 sets the number of steps of the scanning signal (H, V) in the latches 45 and 47 of FIG.

At S2, the shift amount is calculated and transferred to the latch (shift, H, V). This is because the CPU 29
(B) The enlarged scanning signals at the four corners (2500 × 250
The shift amount (the number of steps to be shifted) for making the pixel 0) is calculated and set in the latches 49 and 50 in FIG.

At S3, the enlargement ratio is calculated and transferred to the latch (enlargement, H, V). This is because the CPU 29 determines that the four corners of FIG. 4B have enlarged scanning signals (2500 × 2500).
Pixel) to calculate the enlargement ratio, and the latch 5 in FIG.
Set to 2,53.

At S4, scanning starts, the counter H increases at each clock, and outputs D / A. This increases in the configuration of FIG. 3 until the comparator 46 becomes equal to the value set in the latch 45 every clock, and when it becomes equal, S
5 and reset, and scanning is started again.

At S5, the counter V is incremented by one when the increase of one horizontal scanning signal is completed at S4. This is S4
Each time the increase of one horizontal scanning signal (H) is completed in FIG.
Is repeated, and when the value becomes equal to the value of the latch 47, the comparator 48 is reset and scanning is started again.

FIG. 4B is an explanatory diagram when the scanning signals (H, V) are generated according to the flowchart of FIG. 4A. Here, as for the enlarged image of 2500 × 2500 pixels from 16000 × 16000 pixels, the enlarged image is shifted as shown in the figure just at the center and the corner.

As described above, the CPU 29 sets the latch 45,
At 47, 49, 50, 52, and 53, the number of steps (the number of pixels), the amount of shift (the number of shift steps), and the enlargement ratio of the enlarged image are set arbitrarily and automatically, for example, 16000.
It is possible to generate an enlarged scanning signal (2500 × 2500 pixels, H, V) at the center and 4 corners of 16000 pixels.

FIG. 5 shows an explanatory diagram (scanning) of the present invention.
FIG. 5A-1 shows an example of an image of 16000 × 16000 pixels. (B-1) of FIG. 5 shows the scanning signals (H, V) when the image of (a-1) of FIG. 5 is obtained.

FIG. 5A-2 shows 5000 × 5000.
An example in which a pixel image is obtained at the upper left corner is shown. (B) of FIG.
-2) shows the scanning signals (H, V) when the image of (a-2) in FIG. 5 is obtained. Here, in order to obtain an enlarged image (5000 × 5000 pixels) at the upper left corner of (a-2) in FIG. 5, the scanning is shifted upward by a predetermined amount (predetermined number of steps) from the center, and scanning for 5000 pixels is performed. The signals (H, V) are generated.

FIG. 5A-3 shows 5000 × 5000.
An example in which a pixel image is obtained at the center will be described. (B-
3) shows the scanning signals (H, V) when the image of (a-3) in FIG. 5 is obtained. Here, in order to obtain an enlarged image (5000 × 5000 pixels) in the center of (a-3) in FIG.
The shift amount is 0 (zero), and the scanning signals (H, V) for 5000 pixels are generated.

FIG. 5A-4 shows an enlarged view of the image of FIG. 5A-3. (B-4) of FIG.
(A-4) shows a scanning signal (H, V) when the image is obtained. Here, the enlarged image (5000 × 5000 pixels) in the center of (a-4) in FIG. 5 is enlarged as a whole, and the scanning signals (H,
V).

As described above, high definition (for example, 16000 ×
When scanning over the sample 7 with 16000 pixels), the center,
Images enlarged at a predetermined magnification of, for example, 5 points (5000 × 5000 pixels in FIG. 5) such as upper left, lower left, lower right, and upper right are sequentially displayed, and focus adjustment and astigmatism adjustment are performed for each position, and Memorize each value,
By complementing and adjusting focus and astigmatism between them, focus and astigmatism are always corrected even if high-definition whole or part is extracted and enlarged and displayed,
It is possible to display an image with beautiful high resolution. Also, instead of performing the focus adjustment and the astigmatism adjustment by displaying the enlarged image by sequentially switching over the sample 7 in the order of the center, the upper left, the lower left, the lower right, and the upper right, the enlarged image of these five points is displayed on one screen. The operability is further improved by displaying the images sequentially in chronological order above, and performing focus adjustment and astigmatism adjustment on each of the screens (the five screens in the above example).

FIG. 6 is an explanatory diagram (focus adjustment) of the present invention. In FIG. 6, a latch 71 sets a value for focus adjustment by the CPU.

The D / A 72 converts a digital value set in the latch 72 into an analog value (signal). The objective circuit 73 adds the signal output from the D / A 72 and the signal whose focus has been manually adjusted by a circuit including the illustrated amplifier 73 and supplies the added signal to the objective lens 6. As a result, the current of the objective lens 6 is adjusted, the electron beam for irradiating the sample 7 is narrowed down, and it is possible to obtain a well-focused secondary electron image.

FIG. 7 is an explanatory diagram (embedded fine shift circuit) of the present invention. This is because, for example, when scanning is performed by thinning out the scanning signals (H, V), for example, 16000 × 16000
When the spot diameter of the electron beam in the pixel is exactly equal to the distance between the scanning lines, one (pixel) is extracted (thinned out) every ten lines while maintaining the spot diameter of the electron beam. When the scanning signal (H, B) is generated and the sample 7 is scanned to generate an image, a portion which is not scanned by the electron beam because of a gap of 9 lines (9 pixels) is formed here.
Since it is 0%, a small rectangle (here, a rectangle of 10 × 10 pixels) equal to the interval between scanning lines is subjected to surface scanning (H-direction scanning and V-direction scanning) to prevent the occurrence of moire or the like. At the same time, the S / N ratio is improved.

FIG. 7A shows a circuit configuration diagram. FIG.
In (a), the H-scan generation circuit 81 generates a horizontal scanning signal.

The V scan generating circuit 82 generates a vertical scanning signal. The latch 83 sets the magnitude of a scanning signal for scanning the electron beam from the CPU.

The D / A 84 converts a digital value set in the latch 83 into an analog signal. The arithmetic circuits 85 and 86 multiply the scan signal A from the H scan generation circuit 81 and the V scan generation circuit 82 by the value from the D / A 84 (A × B) to generate Hscan (scan signal (H)) and Vscan (scanning signal (V)) is output.

FIG. 7B shows Hsca of FIG. 7A.
A state in which n and Vscan are input from the left side, and the fine shift coil 5 scans (scans in the horizontal and vertical directions) a small rectangular range equal to the scanning line interval from the right side.

As described above, when there is a gap that cannot be scanned by an electron beam between scanning lines, by performing horizontal scanning and vertical scanning within a small rectangle equal to the interval between scanning lines, moire is generated. Can be eliminated and the S / N ratio can be improved.

FIG. 8 shows an explanatory diagram (filter) of the present invention. This is because when a secondary electron signal generated at that time is detected by performing a surface scan in a rectangular area corresponding to the interval between scanning lines in FIG. 7, the signal in the rectangular area is converted into a signal of one pixel. For this purpose, the light is passed through a high-speed scanning filter.

FIG. 8A shows a circuit configuration. Here, a signal (image signal) from the secondary electron detector 19 is input from the left side, and when the circuit of FIG. 7 operates, a switch is connected to the lower side by a switching signal, and the image signal is passed through a high-speed scanning filter. The image data is input to the A / D image capturing device 21, converted into a digital image signal, and passed to the CPU.

FIG. 8B shows an example of a signal at the time of spotting. When the electron beam is spotted (when the circuit of FIG. 7 is not operated), the S / N ratio is slightly poor and noise is slightly superimposed as shown.

FIG. 8C shows a high-speed scan (when the circuit of FIG. 7 is operated), in which a rectangular area having a scanning line interval is surface-scanned at a high speed. Show the situation. FIG. 8D shows the state of the signal after passing through the filter. This is because the signal obtained when the signal shown in FIG. 8C is passed through the high-speed scanning filter shown in FIG. 2 shows the state of a signal obtained by averaging the signals of FIG. Thus, when the circuit of FIG. 7 is operated, it is possible to display an image that faithfully reflects the surface shape of the sample 7 by averaging the signals obtained when the rectangles of the scanning lines are scanned in a plane, and By averaging, it is possible to improve the S / N ratio and display a high-quality image.

FIG. 9 shows an explanatory diagram (scanning) of the present invention.
This is to explain the circuit configuration and operation when displaying an image in which an arbitrary position (place) is enlarged at an arbitrary magnification within the scanning range of the sample 7.

FIG. 9A shows a circuit configuration diagram. FIG.
(A), the scan generator 12 outputs the scan signal (H,
V).

The change-over switch 91 supplies the scanning signal (H, V) from the scanning generator 12 directly to the deflection coil 3 via the magnification control circuit 15 to display an entire image of the sample scanning range. Alternatively, after adjusting the magnification and the position of the scanning signal (H, V) from the scanning generator 12, the scanning signal (H, V) is supplied to the deflecting coil 3 via the magnification control circuit 15, and an arbitrary enlarged image at an arbitrary position in the sample scanning range. Is displayed.

The magnification adjustment is for adjusting the magnification and for adjusting the magnitude of the scanning signal (H, V). The position adjustment is for adjusting the scanning position, and is for adding a DC component to the scanning signal (H, V).

FIG. 9 (b) shows the relationship between the sample scanning range and the screen which are changed by the magnification adjustment and the position adjustment. Here, the upper part shows the sample scanning range of the electron beam on the sample 7 (the changeover switch 91 in FIG. 9A is the lower part), and the lower part shows the image on the screen.

FIG. 9 (b-1) shows a state in which the inside of a small rectangle substantially at the center of the upper sample scanning range is scanned by the electron beam. In this state, the signal emitted from within the small rectangle at the center of the upper stage is fully displayed on the screen of the lower stage.

FIG. 9B-2 shows a state in which the inside of a small rectangle substantially at the center of the upper sample scanning range is scanned by the electron beam. In this state, a signal (for example, “A” shown) emitted from within the small rectangle at the center of the upper stage is fully displayed on the screen of the lower stage.

FIG. 9B-3 shows a state in which the inside of a small rectangle on the right in the approximate center of the upper sample scanning range is scanned with the electron beam. In this state, the signal emitted from inside the small rectangle at the upper right of the center (for example, "b" shown)
Is fully displayed on the lower screen.

FIG. 9 (b-4) shows a state in which the inside of a small rectangle at the upper right of the upper sample scanning range is scanned by the electron beam. In this state, the signal (for example, “C” shown in the figure) emitted from the upper right corner of the upper rectangle is fully displayed on the lower screen.

As described above, by operating the changeover switch 91, the magnification adjustment, and the position adjustment in FIG. 9A,
As shown in (b-1) to (b-4) of FIG.
It is possible to enlarge and display an image on the screen at an arbitrary magnification at an arbitrary position on the screen.

FIG. 10 is an explanatory diagram (defocus) of the present invention. In this configuration, when the spot diameter of the electron beam is smaller than the interval between the scanning lines, the objective lens 6 is defocused so as to be almost the same as the interval between the electron beams.

In FIG. 10, a latch 92 latches a value to be defocused by the CPU. D / A9
Numeral 3 converts a digital value held in the latch 92 into an analog value.

The focus adjustment was performed by using an electron beam for the sample 7.
When scanning the top, when the diameter of the electron beam is smaller than the interval between the scanning lines, defocus and make it almost the same,
This is to eliminate the occurrence of moiré and to improve the S / N ratio.

FIG. 11 is an explanatory diagram (dynamic focus, part 1) of the present invention. Here, the upper part is the scanning signal (H) and the lower part is the vertical signal (V) dynamic focus.

In FIG. 11, a left / right separation circuit 94 separates a scanning signal (H) into right and left. The vertical separation circuit 95 separates the scanning signal (V) into upper and lower parts.

The correction circuit 96 is a circuit for adjusting dynamic focus correction. The signal synthesizing circuit 98 synthesizes a signal and supplies the signal to the dynamic focus coil 7.

Next, the operation will be described. The scanning signal (H) input from the left side is separated by the left / right separation circuit 94 and input to the correction circuit 96 for correction (H correction, H
2 correction (H square correction)).

Similarly, the scanning signal (V) input from the left side is separated by the upper / lower separation circuit 95 and the correction circuit 96
Are respectively input and corrected (V correction, V2 correction (V
Square correction))).

With the above adjustment, it becomes possible to perform dynamic focusing in conjunction with the scanning signals (H, V). FIG. 12 shows an explanatory diagram (dynamic focus, part 2) of the present invention.

FIG. 12A shows an example of a correction signal. Here, the scanning signals (H, V) are input from the left, and the H2 (H square) generation circuit and the -H2 (H square) generation circuit generate the H2 signal and the -H2 signal, respectively, to be variable. The voltage is input to both ends of the setting resistor, the adjustable resistor is adjusted, and a dynamic correction signal is supplied from the right to the dynamic focus coil 7 in FIG. Then, the variable setting resistance is adjusted so that a high-quality image is obtained when the center and the periphery of the sample 7 are scanned with the electron beam.

FIG. 12B shows an example of four-direction adjustment. On the scanning screen, the variable setting resistors of FIG. 12 are adjusted at each of the left, right, upper, and lower positions as shown (H and H2
(Square of H), V and V2 (square of V), respectively, and perform dynamic focus.

As described above, above the sample scanning range,
Adjustment of the dynamic focus correction is performed on the bottom, left, and right, respectively, and by complementing it, even if the range of scanning the sample 7 with the electron beam is widened, the focus is automatically adjusted and a beautiful image is formed. It can be displayed.

FIG. 13 is an explanatory diagram (dynamic focus, No. 3) of the present invention. This shows a configuration in which the height of the sample 7 is detected and dynamic focus is performed in accordance with the detected height.

FIG. 13A shows a state in which backscattered electron detectors A and B are provided on the left and right sides of the sample 7, respectively. When the electron beam irradiates the sample 7 from above and scans the surface, the reflected electrons are respectively detected by the left detector and the right detector as shown in the figure.

FIG. 13B shows an example in which the sample 7 is convex here. FIG. 13C shows an example of a signal detected by the left detector A. FIG. 13D shows an example of a signal detected by the right detector B.

FIG. 13E shows the difference (AB).
FIG. 13F shows an example of the height 高 (AB). This shows an example of a value obtained by integrating the difference (AB) in FIG. 13E from left to right. Thus, the height information of the surface of the sample 7 is obtained.

FIG. 13G shows a state in which a plurality of sets of FIG. 13F are obtained, three-dimensional height information is obtained and displayed. In this case, a plurality of sets of the detectors shown in FIG. 13A are provided, and the height information shown in FIG. 13F is obtained in a plurality of directions and displayed three-dimensionally.

FIG. 13H shows a state in which the unevenness of the sample 7 is displayed obliquely. (I) of FIG. 13 shows how dynamic focus correction is performed based on height information of the sample 7. This is because the height information of the sample 7 was obtained.
A dynamic focus current corresponding to the height information is supplied to the dynamic focus coil 7 in FIG. 1 to perform dynamic focus.

FIG. 14 is an explanatory diagram (dynamic focus, No. 4) of the present invention. FIG. 14A shows a divided state. This is obtained by dividing the scanning range into meshes for the height information shown in FIG.

FIG. 14B shows a binarized display. This is obtained by dividing height information into a mesh shown in FIG. 14A and binarizing the height information. (C) of FIG.
Shows a state in which the binarized value in FIG. 14B is represented by a rectangular prism of a mesh for easy understanding.

FIG. 14D shows a state where the state of FIG. 14C is smoothed. FIG. 14E shows a state in which dynamic focus correction is performed based on the height information shown in FIG.

As described above, after obtaining the height information of the sample 7 and dividing it into meshes, obtaining the height information of each mesh and smoothing it, it becomes possible to perform dynamic focus correction corresponding to the height.

FIG. 15 is an explanatory diagram (dynamic focus, No. 5) of the present invention. FIG. 15A shows a state in which the sample scanning range is divided into meshes. FIG. 15B shows a state in which the height information obtained in FIG. 13G described above is mapped.

FIG. 15C shows a state where the height is set at the center of each mesh of FIG. 15B by the length of the arrow as shown. (D) of FIG. 15 shows a state where the surface is bent to a curved surface based on the height information of (c) of FIG.

FIG. 15E shows a state in which dynamic focus correction at a height corresponding to the curved surface of FIG. 15D is performed. As described above, after the height information of the sample 7 is obtained and the mesh is divided, the height information of each mesh is obtained and the curved surface is obtained, and then the dynamic focus correction corresponding to the height of the curved surface can be performed.

FIG. 16 is an explanatory diagram (dynamic astigmatism correction, part 1) of the present invention. In FIG. 16, a left / right separation circuit 101 separates a scanning signal (H) into right and left.

The astigmatism correction circuits 102 and 103 are circuits for performing astigmatism correction in the horizontal direction (H).
Is for vertically separating the vertical signal (V). The astigmatism correction circuits 105 and 106 are circuits for correcting astigmatism in the vertical direction (V). The center astigmatism correction circuits 107 and 9 correct astigmatism at the center of the visual field.

The X astigmatism correction addition circuit 108 generates an X astigmatism correction signal. Y astigmatism correction addition circuit 110
Generates an X astigmatism correction signal. With the above circuit configuration, the center of FIG. 17B (to be described later) by the astigmatism correction circuit based on the scanning signals (H, V) input from the left side.
By performing astigmatism correction at the five points of up, down, left, and right, and complementing during that period, it becomes possible to display a beautiful image with the astigmatism corrected over the entire field of view.

FIG. 17 is an explanatory diagram (dynamic astigmatism correction, part 2) of the present invention. FIG. 17A shows an example of a circuit for generating an astigmatism correction signal from a scanning signal. this is,
As shown in the figure, the scanning signal (H, left) is amplified by a + amplifier and a −amplifier and supplied to both ends of a variable resistor, and an astigmatism correction signal (left, H, X, , Left H, Y) and supply them to the astigmatism correction coil 4, respectively.

FIG. 17B shows how the astigmatism correction is performed for each of the center, upper, lower, left, and right points on the sample scanning range. At this time, in the circuit of FIG.
Astigmatism correction is performed at each of the lower, left, and right positions.

As described above, the center of the scanning range of the sample 7
Dynamic astigmatism correction is performed at each of the five points of upper, lower, left, and right, and complementing between them makes it possible to obtain a high-quality image over a high range.

FIG. 18 is an explanatory diagram (digital scanning) of the present invention. FIG. 18A shows a configuration diagram of digital scanning. In FIG. 18A, the controller 112
Reads data from a memory 111 such as in a personal computer, stores the data in a FIFO memory 113, and reads H data and V data read from the FIFO memory in synchronization with a reference clock.
Data is set in each latch, and the data set in the latch is converted into an analog scanning signal (H, V) by a D / A converter and output.

As described above, the data read from the memory 111 is stored in the FIFO memory 113, the H data and the V data are read and set in the latch, and the data set in the latch is converted into an analog scanning signal (H, V), and scanning can be performed with an arbitrary number of steps.

FIG. 18B shows an example of the data structure in V and H. Here, the H data and the V data are represented by 2 bytes, the 15th bit is used as a chip select of the latch, and the remaining 15 bits represent coordinate data.

With the above-described configuration, each bit 15 of the coordinate data is chip-selected, that is, directly switched to convert the coordinate data for the horizontal scanning signal (bits 0 to 14 in the above example) into the D for the horizontal scanning signal. / A to obtain an analog horizontal scanning signal to drive the deflection coil 3 for horizontal scanning, or to convert coordinate data (bits 0 to 14 in the above example) for vertical scanning signal into D / D for vertical scanning signal. A, and obtains an analog vertical scanning signal to obtain a vertical scanning deflection coil 3.
Can be driven. As a result, the coordinate data on the memory is directly switched by the bit 15 0 or 1 and the D / A for the horizontal scanning signal or the D / A for the vertical scanning signal is switched.
/ A can be generated at very high speed to generate each scanning signal independently. Similarly, the astigmatism correction coil 4, the fine shift coil 5, the dynamic focus coil 8 and the like generate high-speed horizontal (X) and vertical (Y) signals from the coordinate data in the memory at high speed. , Can be controlled independently at high speed. As described above, the horizontal and vertical signals supplied to each coil can be independently controlled by the coordinate data on the memory. Therefore, by specifying arbitrary coordinate data on the memory from a display application or the like, any arbitrary Can be generated.

Although one set (horizontal scanning signal and vertical scanning signal) is obtained in the configuration shown in FIG. 18, the enlarged image of the center, upper left, lower left, lower right, and lower right points described above in the coordinate data is obtained. Or an arithmetic circuit is provided on the output side of the D / A in FIG. 18 to instruct from the coordinate data (the center, upper left, lower left, lower right, and upper right five-point enlarged images Based on a generation instruction of a signal to be generated), an enlargement ratio and a shift amount are input, and an enlarged image (for example, 1000) at the center, upper left, lower left, lower right, and lower right of high definition (for example, 16000 × 16000 pixels). (× 1000 pixels) scanning signals are sequentially obtained, the images at that time are displayed on the screen of one display device (5 enlarged images are displayed, respectively), focus adjustment and astigmatism correction are performed, and stored. By scanning the space between each other, A beautiful image can be displayed on any screen (16000 × 16000 pixels).

FIG. 19 shows an explanatory diagram (12-bit RGB conversion table) of the present invention. This RGB conversion table is an example of a table for converting a 12-bit pixel value (gradation) into one-pixel RGB 8-bit gradation. Regarding the values from 0 to 4095 (the numerical range represented by 12 bits) on the left side, when the data is converted into each RGB of 8 bits (the numerical range represented by 0 to 255),
The value obtained by experiment is set. Therefore, a monochrome 12-bit image (16,000 × 16,000)
Is converted to an 8-bit RGB image (16,000 × 16.0
00), the data can be converted with the same number of pixels.

[0127]

As described above, according to the present invention,
A signal generated by scanning the sample with the beam is detected, and a signal of one thousand to several tens of thousands of pixels can be converted into a color image to be displayed, printed, and observed with good gradation and a wide field of view.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of the present invention.

FIG. 2 is an explanatory diagram (thinning-out scanning) of the present invention.

FIG. 3 is an explanatory view (arbitrary step variable scanning, part 1) of the present invention.

FIG. 4 is an explanatory diagram (arbitrary step variable scanning, part 2) of the present invention.

FIG. 5 is an explanatory diagram (scanning) of the present invention.

FIG. 6 is an explanatory diagram (focus adjustment) of the present invention.

FIG. 7 is an explanatory diagram (embedded fine shift circuit) of the present invention.

FIG. 8 is an explanatory diagram (filter) of the present invention.

FIG. 9 is an explanatory diagram (scanning) of the present invention.

FIG. 10 is an explanatory diagram (defocus) of the present invention.

FIG. 11 is an explanatory diagram (dynamic focus, part 1) of the present invention.

FIG. 12 is an explanatory diagram (dynamic focus, part 2) of the present invention.

FIG. 13 is an explanatory diagram (dynamic focus, No. 3) of the present invention.

FIG. 14 is an explanatory diagram (dynamic focus, No. 4) of the present invention.

FIG. 15 is an explanatory diagram (dynamic focus, No. 5) of the present invention.

FIG. 16 is an explanatory diagram (dynamic astigmatism correction, No. 1) of the present invention.

FIG. 17 is an explanatory diagram (dynamic astigmatism correction, part 2) of the present invention.

FIG. 18 is an explanatory diagram (digital scanning) of the present invention.

FIG. 19 is an explanatory diagram (12-bit RGB conversion table) of the present invention.

[Explanation of symbols]

 1: Irradiation system 2: Focusing lens 3: Deflection coil 4: Astigmatism correction coil 5: Fine shift coil 6: Objective lens 7: Sample 8: Dynamic focus coil 11: Arbitrary step scan generator 12: Scan generator 13: Scan Signal switching device 14: Magnification control circuit 15: Magnification control circuit 16: Magnification control switching device 17: Dynamic astigmatism correction control circuit 18: Dynamic focus control circuit 19: Secondary electron detector 20: Signal amplifier 21: Image capture device 23 to 27: I / O 28: Display device 29: CPU 30: Printer 35: Image editing means 36: Image conversion means 51: Fine shift control circuit

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yutaka Hirano 2- 24-12 Hyakunincho, Shinjuku-ku, Tokyo Inside Sanyu Electronics Co., Ltd. (72) Inventor Hiroyuki Teshima 2- 24-12 Hyakunincho, Shinjuku-ku, Tokyo Sanyu F-term (reference) in Electronics Co., Ltd. (G)

Claims (10)

[Claims] 1. A means for irradiating a sample with a narrowly focused beam, a scanning means for oscillating the sample while irradiating the sample with the beam, and a signal generated by scanning the beam on the sample surface. Detecting means for detecting the absorbed signal; means for converting into a digital color signal corresponding to the signal detected by the detecting means; and means for outputting the converted color signal. Scanning image processing apparatus. 2. An objective lens for squeezing charged particles into a charged particle beam and irradiating the sample with a charged particle beam; Scanning means for performing correction, astigmatism correction means for correcting astigmatism generated in a finely focused charged particle beam scanned on the sample surface, a signal generated by scanning the charged particle beam on the sample surface or Detecting means for detecting the absorbed signal; means for converting into a digital color signal corresponding to the signal detected by the detecting means; and means for outputting the converted color signal. Scanning image processing apparatus. 3. When the magnification or the number of scanning lines is changed and the sample is scanned by the scanning means with the beam, it is determined that the space between the scanning lines is empty. 3. The scanning image processing apparatus according to claim 1, wherein the focus is made thicker. 4. When the magnification or the number of scanning lines is changed, and when the scanning means scans the sample with the beam, it is determined that there is a gap between the scanning lines. 3. A scanning image processing apparatus according to claim 1, wherein each of the regions is scanned in a plane. 5. A means for plane-scanning a central part of a predetermined area of a sample and a plurality of peripheral parts to display a signal detected as an enlarged image on a screen, and enlarging the displayed central area. Means for focusing the beam for each of the selected image and a plurality of peripheral enlarged images, and means for performing focus correction of the beam based on the focused value. The scanning image processing apparatus according to claim 1. 6. A position 180 degrees symmetric about the sample,
A plurality of sets of detectors for detecting a signal generated when the beam irradiates the sample; and a means for generating a plurality of sets of differential signals of signals detected by the 180-degree symmetrical detectors. Means for integrating the difference signal in the scanning direction to generate height information in each direction of the sample; and focusing the beam on the basis of the generated height information in each direction of the sample. The scanning image processing apparatus according to claim 1, further comprising a unit that performs alignment. 7. A means for plane-scanning a central part of a predetermined area of a sample and a plurality of peripheral parts to display a signal detected as a magnified image on a screen, and enlarging the displayed central magnified image. Means for performing astigmatism of the beam for each of the adjusted image and a plurality of peripheral enlarged images, and means for performing astigmatism correction of the beam based on the value obtained by performing the astigmatism. 7. The scanning image processing apparatus according to claim 2, wherein 8. A table in which color gradations corresponding to the detected signal gradations are registered, and the detected signals are converted into color signals with reference to the table. The scanning image processing apparatus according to claim 1 or 2, wherein: 9. When converting the detected signal into a color signal, a tone of a color signal corresponding to the tone of the detected signal is created based on two designated colors. The scanning image processing apparatus according to claim 1, wherein the conversion is performed after conversion. 10. The color signal of a color data format used by a printing apparatus when the detected signal is 8 bits or more, and when the color signal is RGB, 8 bits each, or when the color signal is for printing. The scanning image processing apparatus according to claim 1 or 2, wherein the number of bits of the color is set as the following.