JP6343508B2 - Contrast / brightness adjustment method and charged particle beam apparatus - Google Patents

Description

  The present invention relates to a method and apparatus for determining contrast / brightness of an image, and more particularly, a method for determining contrast / brightness of a charged particle beam device capable of changing a scanning speed of a beam, and determination of the contrast / brightness. The present invention relates to an apparatus for performing a law.

  In the semiconductor market, semiconductor devices and the like have been highly integrated and miniaturized, and there is a constant demand for improved performance of charged particle beam apparatuses that perform observation, measurement, and inspection of these samples. For example, when a scanning electron microscope (hereinafter abbreviated as “SEM (Scanning Electron Microscope)”), which is an embodiment of a charged particle beam apparatus, is used for industrial purposes, mainly in an inspection process for measuring pattern dimensions. Often used. In the SEM used for such applications, it is required to reduce the difference in measurement characteristics between a plurality of apparatuses. Therefore, it is desirable to align the image quality of the display image when observing the same sample.

  One of the adjustments necessary to align the image quality is image contrast / brightness adjustment. In the sample, there is a portion with extremely high luminance or a portion with low luminance locally due to adhering dust or the like, and the contrast / brightness may not be an appropriate value. Therefore, a method using a histogram is generally used as a method for adjusting contrast and brightness. First, a histogram is generated from an image after beam irradiation (hereinafter abbreviated as “scan”), and the generated histogram is compared with a reference histogram. By determining the gain (contrast) and the offset (brightness) so as to match the form with the reference histogram, the contrast and the brightness are determined so as to be unified to a constant brightness.

  Patent Document 1 describes a method of adjusting the amplification factor of a detector so as to correct changes in contrast and brightness when a sample is tilted. Japanese Patent Application Laid-Open No. 2004-228561 describes a method of measuring the noise amount of an image and adjusting the contrast and brightness based on the noise amount.

JP 2008-103107 A JP 2009-181863 A

  On the other hand, when the beam irradiation conditions are changed, for example, by increasing the beam scanning speed, the contrast / brightness adjustment method that unifies the brightness to a certain level reduces the resolution of the display image. Although the same pattern is scanned, the scanning speed is different, so that the resolution is lowered and the image quality of the display image cannot be made uniform. The resolution here means the minimum interval between two points that can be distinguished on the image.

  In recent years, semiconductor devices are increasingly miniaturized and complicated, and it is expected that there will be an increased need to perform beam irradiation after appropriately selecting beam conditions according to the composition of the pattern formed on the sample. Is done. On the other hand, when the beam condition is changed as described above, the resolution may change. For example, in a CD-SEM (Critical Dimension-SEM) that measures the line width of a semiconductor device, the output length measurement value may change depending on the change in resolution. For example, even if a pattern having the same dimension is measured, the dimension value may change due to a change in resolution.

  As described above, the change in resolution becomes a factor that decreases the reproducibility of length measurement. However, the contrast and brightness adjustment methods disclosed in Patent Documents 1 and 2 are not designed to reduce the resolution.

  In the following, a contrast, a brightness adjustment method, and a charged particle beam apparatus for the purpose of enabling adjustment of contrast and brightness according to the scanning speed that causes resolution and resolution fluctuation are proposed.

  As one aspect for achieving the above object, a contrast / brightness adjustment method for adjusting contrast and brightness of an image obtained when a charged particle beam is scanned on a sample, comprising: The calculation of the resolution index value obtained from the image obtained based on the scanning of the above, or the scanning speed of the charged particle beam is set, the relationship between the resolution index value or the scanning speed and the information on the contrast and brightness Using the table or the calculation formula, the information on the contrast and brightness according to the scanning speed or the resolution index value of the image obtained based on the scanning of the charged particle beam is acquired, and the information is used. Contrast and brightness adjustment to adjust the contrast and brightness of the image Law proposes.

  Further, as another aspect for achieving the above object, a detector for detecting a signal obtained based on scanning of a charged particle beam emitted from a charged particle source onto a sample, and An image signal processing apparatus that calculates a resolution evaluation value of a formed image based on a detected signal and / or a charged particle beam apparatus that includes a scanning speed setting unit that sets a scanning speed of the charged particle beam. Thus, a charged particle beam apparatus including a contrast / brightness adjusting unit that adjusts contrast and brightness of the image based on the calculated resolution evaluation value or the set scanning speed is proposed.

  According to the above configuration, it is possible to adjust the contrast and brightness according to the resolution and the scanning speed that causes the fluctuation of the resolution.

Diagram explaining the decrease in resolution due to higher scanning speed Diagram explaining improvement of resolution by contrast / brightness adjustment The block diagram of the image signal processing apparatus which adjusts contrast and brightness based on the index value which shows the resolution calculated | required from the image. The figure explaining the outline | summary of the resolution calculation part which calculates a resolution index value. The figure explaining the outline | summary of a contrast brightness adjustment part. FIG. 4 is a diagram illustrating an example of a contrast and brightness adjustment process using the image signal processing apparatus illustrated in FIG. 3. The schematic block diagram of a charged particle beam apparatus. The flowchart explaining the process of adjusting contrast and brightness based on a resolution index value and luminance information. The figure which shows an example of the GUI screen which sets the conditions for contrast and brightness adjustment. The figure which shows an example of the GUI screen which sets the conditions for performing contrast brightness adjustment automatically. The figure explaining an example of the target contrast determination table. The figure explaining an example of a target brightness determination table. The figure explaining an example of a gain value determination table. The figure explaining an example of a bias value determination table.

  In recent semiconductor devices, an ArF resist and a low-k material necessary for realizing miniaturization are used. These materials necessary for miniaturization tend to change device characteristics by scanning, and pattern erosion (hereinafter abbreviated as shrink) and deformation are likely to occur when observed with an SEM. For this reason, in observation, measurement, or inspection by SEM, it is an effective means to prevent pattern destruction by increasing the scan speed and not irradiating the sample with a beam as much as possible. As pattern miniaturization continues, the need for higher scan speeds will increase.

  FIG. 1 illustrates a mechanism for reducing the resolution, taking images acquired at different scan speeds (1 × speed and 2 × speed) as an example. The SEM first scans the pattern. Light is emitted when secondary electrons or reflected electrons generated by scanning strike the detector, and a waveform signal is generated from the relationship between the brightness information at the time of light emission and the elapsed time. For the waveform signal, the scan position is determined from the scan speed, and the brightness information of the waveform signal is stored in one corresponding pixel. Since an image is an aggregate of pixels and is composed of rows and columns, an image is formed by performing these processes on a matrix.

  The waveform signal in FIG. 1 is adjusted so that the brightness of the image becomes constant by adjusting the contrast and brightness, and is a waveform signal having a similar shape. Compared with the 1 × speed scan, the 2 × speed scan has a scan speed of 2 times, so that the interval for acquiring the brightness from the waveform signal is ½. In the image acquired by the 1 × speed scan, the brightness of the waveform signal at time 1 corresponds to the brightness of the pixel 1 and becomes bright, and the brightness at time 2 of the waveform signal corresponds to the brightness of the pixel 2 and becomes dark. On the other hand, in the image acquired by the double speed scan, the brightness of the waveform signal at time 3 corresponds to the brightness of the pixel 3 and the waveform signal at time 4 corresponds to the brightness of the pixel 4, and the brightness of the waveform signal at time 5 Since the brightness of pixel 5 and the waveform signal at time 6 corresponds to the brightness of pixel 6, it becomes dark.

  In this way, when the contrast / brightness adjustment method that adjusts the brightness to a certain level is applied to the waveform signal obtained by increasing the scan speed, the waveform signal sampling interval is short. Are distributed over several pixels. As a result, the image has no edges (having reduced resolution) as a whole.

  From the above, in the embodiments described below, a contrast / brightness adjustment method and a charged particle beam apparatus capable of maintaining high resolution even when the scanning speed is increased will be described.

  As one aspect for achieving the above object, there is provided a method and apparatus for obtaining an index value indicating resolution from an image obtained by a charged particle beam apparatus or the like and adjusting contrast and / or brightness based on the index value. suggest.

  FIG. 2 illustrates the principle of maintaining a high resolution, taking as an example images acquired at different scan speeds (1 × speed and 2 × speed). Compared with the 1 × speed scan, the 2 × speed scan has a scan speed of 2 times, so that the interval for acquiring the brightness from the waveform signal is ½. Therefore, when the resolution of the image is low, the contrast and brightness are changed, and the waveform signal is adjusted so that the brightness of the waveform signal is the same at time 7 of the 1 × speed scan and time 9 of the 2 × speed scan. To do. The brightness of the waveform signal at the elapsed time 8 of the 1 × speed scan and the elapsed time 10 of the 2 × speed scan is the same. Thereby, the brightness of the pixels 7 and 8 by the 1 × speed scan and the brightness of the pixels 9 and 10 by the 2 × speed scan can be made the same, and the resolution of the image formed from the waveform signal can be made uniform. Become.

  In this way, it is possible to set the contrast and brightness according to the scanning speed and resolution, so that the resolution can be made uniform, and measurement and inspection at an arbitrary scanning speed can be performed without reducing the length measurement reproducibility. Is possible. It should be noted that a slower scanning speed can obtain a larger amount of signal and forms a high-resolution image, so that the resolution of an image obtained at a slower scanning speed (in the above case, 1 × speed scanning) is faster. It is desirable to match the resolution of the image obtained by scanning at the scanning speed. However, from the viewpoint of length measurement reproducibility, it is not necessary to do so. The reference resolution is determined, and the contrast and brightness conditions are set so that the reference resolution can be obtained even when the scanning speed is changed. You may make it do.

  According to the above configuration, since the resolution can be made uniform in a state where the scanning speed is increased, it is possible to form a high resolution image without destroying the miniaturized pattern.

Hereinafter, based on a resolution index value obtained from an image, a method and an apparatus for performing contrast / brightness adjustment, and a computer program for calculating conditions for performing the adjustment in a computer will be described using specific examples. explain.
The image signal processing apparatus described in the present embodiment includes a resolution index value calculating unit that calculates a resolution index value, a contrast and brightness to be adjusted based on the resolution index value, and a gain value and a bias of the signal amplifier. Contrast / brightness adjusting means for determining the value is provided.

  In the method, apparatus, and computer program described in this embodiment, the brightness of the required image is assumed (estimated or the relationship is defined in advance) by comparing the target resolution with the current resolution, and the contrast. And adjust the brightness. According to such a configuration, it is possible to use a high-speed scan to reduce the beam irradiation onto the sample without considering the reduction in resolution, and it is possible to suppress device characteristic deterioration.

  In the following description, an SEM has been described as an example of an image forming apparatus or a signal acquisition apparatus. However, the present invention is not limited to this. For example, a secondary obtained by irradiating a sample with an ion beam made of helium ions or liquid metal ions. An image forming apparatus or a signal acquisition apparatus is applied to other charged particle beam apparatuses such as a focused ion beam apparatus that acquires images and signals by detecting electrons and secondary ions. Anyway.

  Hereinafter, specific embodiments will be described in detail with reference to FIGS. 3 to 6. FIG. 3 is a diagram illustrating an aspect of the image signal processing apparatus. The image signal processing apparatus 10 includes a resolution index value calculation unit 13, a luminance information extraction unit 14, and a contrast / brightness adjustment unit 15 whose adjustment target is a signal amplifier. In the present embodiment, it is assumed that the image signal processing apparatus 10 is generally configured by a computer including a CPU (Central Processing Unit) and a memory, and executes signal processing therein by digital processing. However, you may comprise by hard wired.

  The resolution index value calculation unit 13 receives the image 11 formed by electrons emitted from the sample, calculates the resolution of the image, and outputs a resolution index value 16. The resolution index value is a degree of deviation between the target resolution and the resolution of the image 11. The luminance information extraction unit 14 receives the image 11 and outputs luminance information 17 of the image. The luminance information 17 becomes the current contrast and brightness of the image 11.

  The contrast / brightness adjusting unit 15 receives the resolution index value 16 calculated by the resolution index value calculating unit 13 and the luminance information 17 extracted by the luminance information extracting unit 14 as input, and uses the contrast and brightness to achieve the target resolution. The control signal 18 of the signal amplifier for changing is output. The control signal of the signal amplifier indicates a gain value and a bias value for setting to the signal amplifier.

Details of the resolution index value calculation unit will be described with reference to FIG. The resolution index value calculation unit 13 includes a resolution extraction unit 21, a target resolution output unit 22, and a resolution divergence calculation unit 25, and has a function of calculating the resolution index value 16 from the image 11.
The resolution extraction unit 21 extracts a resolution parameter 23 from the image 11. The resolution parameter can be composed of information such as a numerical value obtained by calculating a luminance gradient of the pattern edge portion and converting it to a beam diameter to be irradiated.

  The target resolution output unit 22 outputs a target resolution parameter 24. The target resolution parameter is configured by inputting from the GUI by an operator or outputting a predetermined value. The resolution divergence calculating unit 25 outputs a resolution index value 16 by obtaining the divergence (difference) between the resolution parameter 23 and the target resolution parameter 24.

  Next, details of the contrast / brightness adjustment unit will be described with reference to FIG. The contrast / brightness adjustment unit 15 includes a target contrast determination unit 31, a target brightness determination unit 32, a gain value determination unit 35, and a bias value determination unit 36. Based on the resolution index value 16, contrast and brightness as adjustment targets. And having the function of determining the gain value and bias value of the signal amplifier from the target contrast 33, the target brightness 34, and the luminance information 17.

  The target contrast determination unit 31 receives the resolution index value 16 and outputs a target contrast 33. This target contrast is a target value for adjusting the contrast of the image 11. The target contrast to be output is prepared as a table by measuring the relationship between the resolution index value and the contrast in advance. The relationship may be given as a calculation formula. In addition, for example, the relationship between the resolution index value 16 and the target contrast or contrast adjustment amount is tabulated in advance, the contrast adjustment amount is read based on the input index value, and gain control is performed according to the adjustment amount. The relationship between the input index value and the gain value may be tabulated in advance, and the gain value may be read based on the input index value.

  The same applies to the target brightness determination unit described later. Such tables and arithmetic expressions are stored in advance in a predetermined storage medium, and can be read out as necessary. The storage medium may be provided in the image signal processing apparatus, or may be stored in an external storage medium so that it can be read out as necessary. The expression indicating the relationship between the resolution index value and the contrast can be expressed by a first-order or multi-order arithmetic expression, and the contrast is obtained by substituting the resolution index value into the arithmetic expression. Good.

  FIG. 11 is a diagram illustrating an example of the target contrast determination table. In this table, the relationship between a plurality of target contrasts and a plurality of resolution index values is tabulated. A gain value determination unit 35, which will be described later, determines a gain value based on, for example, the difference between the current contrast and the target contrast, and controls the signal amplifier. When the contrast adjustment amount is stored in the table, a gain value determination unit 35 described later determines a gain value corresponding to the adjustment amount and controls the signal amplifier.

  The target brightness determining unit 32 receives the resolution index value 16 and outputs a target brightness 34. This target brightness is a target value for adjusting the brightness of the image 11. The output target brightness is prepared as a table by measuring the relationship between the resolution index value and the brightness in advance. The relationship may be given as a calculation formula. FIG. 12 is a diagram illustrating an example of the target brightness determination table. The concept is the same as the target contrast determination table.

  The gain value determination unit 35 receives the target contrast 33 and the luminance information 17 and outputs the gain value of the control signal 18 of the signal amplifier. The output gain value is determined in advance by measuring the relationship between contrast and luminance information and the gain value of the signal amplifier, and inputting the target contrast and luminance information (current contrast). FIG. 13 is a diagram illustrating an example of the gain value determination table. In this table, for each combination of the current luminance (current contrast) and the target contrast, the gain value of the signal amplifier (in this example, the DAC value or the control amount of another amplifier may be registered) is registered. ing.

  The bias value determination unit 36 receives the target brightness 34 and the luminance information 17 and outputs the bias value of the control signal 18 of the signal amplifier. The output bias value is determined in advance by measuring the relationship between brightness, luminance information, and the bias value of the signal amplifier, and inputting the target brightness and luminance information (current brightness). FIG. 14 is a diagram illustrating an example of the bias value determination table. The concept is the same as that of the gain value determination table.

  The control signal 18 (gain value / bias value) of the signal amplifier determined by the contrast / brightness adjustment unit 15 is output to the signal amplifier, and the signal amplifier controls the waveform signal using the control signal of the signal amplifier. The image contrast and brightness are set as target values.

  When the resolution index value is calculated in the state in which the target contrast and the target brightness are set, it matches the target resolution.

  Next, the influence of contrast and brightness adjustment on the waveform signal will be described with reference to FIG. In the contrast adjustment of the waveform signal, the maximum value of the waveform signal is changed. The waveform signal (FIG. 6A) is multiplied by a gain value (amplification degree) which is a control signal of the signal amplifier output from the contrast / brightness adjustment unit 15 (FIG. 6B), and the maximum value of the waveform signal is obtained. By changing, the ratio of the white part and the black part on the image is adjusted.

  In the brightness adjustment of the waveform signal, the average value of the waveform signal is changed. By adding the bias value, which is the control signal of the signal amplifier output from the contrast / brightness adjustment unit 15 to the waveform signal (FIG. 6C), and changing the average value of the waveform signal, the brightness of the entire image is adjusted. Adjust the degree. The waveform signal obtained by these becomes the adjusted waveform signal 53 (FIG. 6D) set to the target contrast and the target brightness.

  According to the present embodiment, since the scan speed is increased and the contrast and brightness can be adjusted to achieve a high target resolution in a state in which the resolution of the display image is lowered, It is possible to prevent changes in device characteristics due to suppression of the beam irradiation amount.

  Hereinafter, an example in which the above-described image signal device is applied to a charged particle beam device will be described with reference to FIGS. As shown in FIG. 7, an image signal processing apparatus 10 that processes an image signal obtained by the charged particle beam apparatus is connected to the output side of the charged particle beam apparatus.

  The charged particle beam device 60 includes a signal amplifier 70 that amplifies a detection signal output from the detector in a mirror body 61 that houses a beam source 64, a focusing lens 62, an objective lens 65, a detector 69, an XY stage 68, and the like. A display image generation unit 71 that forms the waveform signal 12 output from the signal amplifier in a display image, the image signal processing device 10, and an image display 72 are connected.

  In the mirror 61, when the charged particle beam 63 emitted from the beam source 64 is irradiated onto the sample 66, secondary electrons, reflected electrons, and the like are emitted from the sample portion irradiated with the charged particle beam 63, and the detector. 69 detects them. The detected signal is amplified by the signal amplifier 70 and output to the display image generation unit 71 as the waveform signal 12. At this time, the deflection of the charged particle beam 63 is controlled so as to scan the observation region of the sample 66. The sample 66 is fixed to a sample holder 67 installed on the XY stage 68, and the center position of the observation region of the sample 66 is determined by horizontal movement control of the XY stage 68.

  The display image generation unit 71 receives the waveform signal 12 output from the signal amplifier 70 as an input, generates a bitmap image 11, and stores it in an image memory configured by a RAM (Random Access Memory) or the like. The image signal processing apparatus 10 receives the image 11 stored in the image memory, calculates a resolution index value, and determines a control signal 18 of the signal amplifier based on the index value.

  The operation of the image signal processing apparatus 10 when applied to a charged particle beam apparatus will be described using the flowchart of FIG. First, the image 11 generated from the display image generation unit 71 is acquired (step S10). Next, the luminance information extraction unit 14 extracts luminance information of the image (step S11). Next, the resolution index value calculation unit 13 calculates the resolution index value of the image (step S12). A target value (target contrast and target brightness) is determined from the extracted luminance information and the calculated resolution index value (step S13).

  Next, the luminance information extracted from the image is compared with the target value (step S14). If the luminance information does not reach the target value in the determination of step 14, it is determined that contrast / brightness adjustment is necessary, and the contrast / brightness adjustment unit 15 determines the target value (target contrast and target brightness) from A gain value and a bias value are determined (step S15). The determined gain value and bias value are set in the signal amplifier 70, and the contrast and brightness of the image are adjusted (step S16).

  On the other hand, if the luminance information has reached the target value in the determination in step 14 in which the image is acquired and the luminance information extracted from the image is compared with the target value, the contrast / brightness adjustment is terminated, and the image display In 72, an image after contrast / brightness adjustment is displayed. The image display 72 may display an image being adjusted for the purpose of confirming a change in contrast and brightness.

  As described above, in a charged particle beam device having an image processing signal device that performs contrast / brightness adjustment based on the resolution index value obtained from the image, the contrast and brightness of the image are targeted by repeatedly performing the contrast / brightness adjustment. The target resolution can be achieved as close as possible to the value.

  FIG. 9 is a diagram illustrating an example of a GUI (Graphical User Interface) screen for performing contrast / brightness adjustment. This screen is displayed on the image display 72, and the operator uses this screen to set execution conditions and adjust contrast and brightness.

  First, the operator activates the execution screen 400 on the image display 72 and determines whether or not to perform contrast / brightness adjustment from the sample image displayed on the image display screen 407. Next, as an adjustment method, adjustment 402 only for luminance information or adjustment 403 based on resolution is selected, and an automatic adjustment button 401 is pressed. In response to pressing of the automatic adjustment button 401, contrast / brightness adjustment is started by the previously selected adjustment method.

  The adjustment 402 only for luminance information is a mode in which contrast and brightness are adjusted so that the luminance becomes a preset target value without considering the resolution. The resolution-based adjustment 403 is a mode for adjusting the contrast and brightness by calculating a resolution index value according to the processing flow of FIG. In the adjustment 403 based on the resolution, the resolution index value at the time of adjustment can be set like the conditions A404, B405, and C406, and the operator selects the adjustment condition according to the pattern shape, for example. can do. The image display screen 407 displays a sample image after contrast / brightness adjustment, which is used for visual confirmation of whether or not the adjustment is properly performed. For example, when contrast / brightness adjustment clearly fails, the operator can determine whether readjustment is necessary by looking at the state of the image display screen 407. After finishing the contrast / brightness adjustment, the operator presses a close button 408 to close the execution screen 400 and finish the adjustment.

  As described above, by preparing means to select and execute adjustments based only on luminance information and adjustments based on resolution from the execution screen, the optimum adjustment means can be selected based on the usage conditions of the charged particle beam device. It becomes possible to do. In this embodiment, the button is used as the function selection unit, but the expression of the adjustment type selection method is not limited to this.

  FIG. 10 is a diagram for explaining an example of a condition setting screen (GUI screen) for setting conditions for performing automatic operation in the charged particle beam apparatus. The condition setting screen 500 is displayed on the image display 72 as one of recipe files for performing automatic operation.

  First, the operator activates the condition setting screen 500 and then selects the sample pattern flag 501 or the adjustment-specific pattern flag 502 used for contrast / brightness adjustment.

By selecting the flag 501 or 502, it is determined whether to use the sample on the stage or the adjustment pattern. When the sample pattern flag 501 is selected, the stage coordinates of the pattern, the sample image acquisition magnification, and the number of frames for acquiring the sample image are also input from the numerical value input windows 503, 504, and 505, respectively. When the adjustment dedicated pattern flag 502 is selected, the stage coordinates, the magnification, and the number of frames stored in advance are set in the respective numerical value input windows. Note that the number of frames set here is the number of scan image integrations for forming a pattern image.
Next, ON / OFF of contrast / brightness adjustment is selected. If the contrast / brightness adjustment flag 506 is ON, adjustment is performed. Since the adjustment is not performed if the flag 506 is OFF, it is desirable to select under the condition that the contrast / brightness adjustment is not necessary.

  When the contrast / brightness adjustment flag 506 is ON, either an adjustment 507 based only on luminance information or an adjustment 508 based on resolution can be selected as an adjustment method. The brightness information only adjustment 507 is a mode in which the contrast and brightness are adjusted so that the brightness becomes a preset target value without considering the resolution.

  The resolution-based adjustment 508 is a mode for adjusting the contrast and brightness by calculating an index value indicating the resolution in accordance with the processing flow of FIG.

  In the adjustment 508 based on the resolution, the resolution index value at the time of adjustment can be set as in the conditions A509, B510, and C511, and the operator selects the adjustment condition according to the pattern shape, for example. can do.

  As described above, if the contrast / brightness adjustment based on the resolution can be selected on the condition setting screen as one of the recipe files, it can also be applied during automatic operation.

  In the present embodiment, the flag is used to explain the condition setting screen of the automatic driving function, but the notation of the flag and the expression of the adjustment type selection method are not limited thereto.

  As is clear from the above description, according to the above-described embodiment, it is possible to select an adjustment based only on luminance information or an adjustment based on a resolution index value suitable for the user's preference.

  For example, if it is acceptable to irradiate the sample with an electron beam, it may be desirable to adjust contrast or the like based on the luminance of the image. Therefore, as in the GUI screens illustrated in FIGS. 9 and 10, the mode for adjusting the contrast / brightness based on the luminance information and the mode for adjusting the contrast / brightness based on the resolution index value are arbitrarily switched. With this configuration, the apparatus conditions can be set in consideration of the type of sample and the accuracy of contrast / brightness adjustment.

  In all the above embodiments, the target contrast and the target brightness may be obtained by using the scan speed as an index value instead of the resolution. In this case, the scanning speed information set by a setting device (not shown), etc., and the tables illustrated in FIGS. 11 to 14, the scanning speed, contrast, brightness, gain value, or It is preferable to set contrast or the like using a table in which bias values are associated and stored. The set scanning speed is set as a scanning condition of a scanning deflector (not shown).

DESCRIPTION OF SYMBOLS 10 Image signal processor 11 Image 12 Waveform signal 13 Resolution index value calculation part 14 Luminance information extraction part 15 Contrast / brightness adjustment part 16 Resolution index value 17 Luminance information 18 Control signal (gain value / bias value) of signal amplifier
21 Resolution Extractor 22 Target Resolution Output Unit 23 Resolution Parameter 24 Target Resolution Parameter 25 Resolution Deviation Calculation Unit 31 Target Contrast Determination Unit 32 Target Brightness Determination Unit 33 Target Contrast 34 Target Brightness 35 Gain Value Determination Unit 36 Bias Value Determination Unit 50 Before Adjustment Waveform signal 51 Maximum value adjustment by multiplying gain value (target contrast)
52 Average value adjustment by adding bias values (target brightness)
53 Waveform signal after adjustment (target contrast and target brightness)
60 charged particle beam device 61 mirror body 62 focusing lens 63 charged particle beam 64 beam source 65 objective lens 66 sample 67 sample holder 68 XY stage 69 detector 70 signal amplifier 71 display image generation unit 72 image display

Claims (12)

In a contrast / brightness adjustment method for adjusting contrast and brightness of an image obtained when a charged particle beam is scanned on a sample,
And computation resolution index value obtained from the obtained image based on the scanning of the charged particle beam to the sample, using a table or an arithmetic expression indicating the relationship between the resolution index value and the information on the contrast and brightness Te, the acquired information about the contrast and brightness according to the resolution index value of an image obtained on the basis of the scanning of the previous SL charged particle beam, the contrast brightness adjust the contrast and brightness of the image using the information Adjustment method. In claim 1,
A table in which the relationship between the resolution index value and target contrast, contrast adjustment amount, or gain value of the amplifier of the detector is registered, or the resolution index value and target contrast, contrast adjustment amount, or the amplifier of the detector A contrast / brightness adjustment method, characterized in that a signal for adjusting the contrast is generated based on an arithmetic expression indicating a relationship with a gain value. In claim 1,
A table in which the relationship between the resolution index value and target brightness, brightness adjustment amount, or bias value of the amplifier of the detector is registered, or the resolution index value and target brightness, brightness adjustment amount, or the amplifier of the detector A contrast / brightness adjustment method, wherein a signal for adjusting the contrast is generated based on an arithmetic expression indicating a relationship with a bias value. In claim 1,
A contrast / brightness adjustment method, wherein the resolution index value is obtained for the image after the contrast / brightness adjustment. In claim 1,
A contrast / brightness adjustment method, comprising: generating a control signal of an amplifier of the detector based on luminance information of the image and the resolution index value . A detector for detecting a signal obtained based on scanning of a charged particle beam emitted from a charged particle source onto a sample, and a resolution evaluation value of a formed image based on the signal detected by the detector. a charged particle beam apparatus provided with an image signal processing equipment to calculate,
A charged particle beam apparatus comprising a contrast / brightness adjusting unit that adjusts contrast and brightness of the image based on the calculated resolution evaluation value . In claim 6,
The contrast / brightness adjustment unit is a table in which a relationship between the resolution index value and a target contrast, a contrast adjustment amount, or a gain value of an amplifier of the detector is registered, or the resolution index value, a target contrast, and a contrast adjustment. A charged particle beam device, wherein the contrast is adjusted based on an arithmetic expression indicating a relationship with an amount or a gain value of an amplifier of the detector. In claim 6,
The contrast / brightness adjustment unit is a table in which a relationship between the resolution index value and target brightness, brightness adjustment amount, or bias value of the amplifier of the detector is registered, or the resolution index value, target brightness and brightness adjustment. A charged particle beam apparatus, wherein the contrast is adjusted based on an arithmetic expression indicating an amount or a relationship with a bias value of an amplifier of the detector. In claim 6,
The charged particle beam apparatus, wherein the image signal processing apparatus obtains the resolution index value for the image after the contrast / brightness adjustment. In claim 6,
The charged particle beam device, wherein the contrast / brightness adjusting unit is controlled by an amplifier of the detector based on luminance information of the image and the resolution index value. A charged particle source that emits a charged particle beam, a detector that detects a signal obtained based on irradiation of the sample with the charged particle beam, and a contrast of the image based on the signal detected by the detector In charged particle beam equipment equipped with contrast / brightness adjustment unit that adjusts brightness
The contrast / brightness adjustment unit has a first adjustment mode for adjusting contrast and brightness based on the resolution index value of the image, and a second adjustment mode for adjusting contrast and brightness based on the luminance information of the image. A charged particle beam apparatus comprising: In claim 11,
The contrast / brightness adjustment unit obtains a resolution index value of the image in the first adjustment mode, and adjusts the contrast and brightness of the image based on the resolution index value. Particle beam device.