JPWO2016121471A1 - Charged particle beam equipment that creates analytical images from secondary particle images - Google Patents

Abstract

An object of the present invention relates to greatly reducing the acquisition time of an analysis image. The present invention relates to the pseudo formation of an analysis image from a secondary particle image (111-114) of a desired processed surface based on the correlation between the secondary particle image of the processed surface and the analyzed image. Preferably, a three-dimensional image is reconstructed based on the analysis image (121-122) actually acquired and the analysis image (131-132) formed in a pseudo manner. According to the present invention, since a large number of analysis images necessary for three-dimensional reconstruction can be acquired in a short time without acquiring an analysis image for each processing surface, the analysis efficiency is improved. In addition, damage to the sample due to the electron beam can be reduced, and the reliability of the analysis is improved.

Description

  The present invention relates to a charged particle beam apparatus that repeatedly performs cross-section processing using an energy beam and observation and analysis of a cross-section. Preferably, the present invention relates to a charged particle beam apparatus that reconstructs an analysis image three-dimensionally.

  There is a technique called three-dimensional reconstruction, in which three-dimensional data is constructed by stacking two-dimensional image data. Three-dimensional reconstruction is an effective tool that can be used to intuitively understand the internal structure of an object. If a 3D printer is used, a three-dimensional model can be created from three-dimensional data.

  As one of the three-dimensional reconstructions, there is a method called FIB / SEM tomography that performs three-dimensional reconstruction by alternately removing the sample surface with a focused ion beam (FIB) and acquiring an image with a scanning electron microscope (SEM). is there.

  For example, in Japanese Patent Application Laid-Open No. 9-115861 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2013-19900 (Patent Document 2), in a processing observation apparatus provided with an FIB apparatus and an SEM, X is determined for each processing surface by FIB irradiation. Analysis images are acquired by line analysis (EDX) or the like, and three-dimensional reconstruction is performed from these analysis images.

Japanese Patent Laid-Open No. 9-115861 JP2013-19900A

  The inventor of the present application diligently studied to improve the efficiency of three-dimensional reconstruction from an analysis image, and as a result, the following knowledge was obtained.

  Acquisition of analysis images by EDX or the like may take at least 5 minutes per image, and it may take 20 minutes or more when the resolution is increased. For this reason, 3D reconstruction from analysis images that require acquisition of a large number of analysis images Took a lot of time.

  An object of the present invention relates to greatly reducing the acquisition time of an analysis image.

  The present invention relates to forming an analysis image in a pseudo manner from a secondary particle image on a desired processed surface based on the correlation between the secondary particle image on the processed surface and the analyzed image. Preferably, the three-dimensional reconstruction is performed based on the actually acquired analysis image and the pseudo-formed analysis image.

  According to the present invention, since a large number of analysis images necessary for three-dimensional reconstruction can be acquired in a short time without acquiring an analysis image for each processing surface, the analysis efficiency is improved. In addition, damage to the sample due to the electron beam can be reduced, and the reliability of the analysis is improved.

Illustration of the principle of three-dimensional reconstruction that artificially forms an analysis image Schematic configuration diagram of FIB-SEM according to Example 1 Explanatory drawing of the three-dimensional reconstruction algorithm concerning Example 1. FIG. Schematic configuration diagram of FIB-SEM according to Example 2 Explanatory drawing of the three-dimensional reconstruction algorithm concerning Example 3. Fig. 4 is a flowchart of a three-dimensional reconstruction algorithm according to the fourth embodiment. Flow diagram of three-dimensional reconstruction algorithm according to embodiment 5 Flow diagram of three-dimensional reconstruction algorithm according to embodiment 6 Flow diagram of three-dimensional reconstruction algorithm according to the seventh embodiment

  FIG. 1 is an explanatory diagram of the principle of three-dimensional reconstruction for forming an analysis image in a pseudo manner.

  This three-dimensional reconstruction is performed in a charged particle beam apparatus that repeatedly performs processing using an energy beam such as FIB and observation and analysis of a processed surface using an SEM on a stacked structure of a solid-state device. Based on the correlation between the particle image and the analysis image, this processing surface can be obtained by acquiring a secondary particle image for a certain processing surface by incorporating an algorithm for forming an analysis image from the secondary particle image of the desired processing surface. The analysis image is generated in a pseudo manner without actually acquiring the image, and a three-dimensional image is reconstructed using the pseudo analysis image.

  After a cross section is formed on the sample by irradiation with an energy beam, the processed surface is observed with an SEM to obtain a secondary particle image 111 such as a BSE (reflected electron) image. Further, an analysis image 121 such as an EDX mapping (energy dispersive X-ray analysis) image is also acquired for this processed surface. Thereafter, the next processed surface is formed by the energy beam irradiation again. Then, this processed surface is observed with an SEM to obtain a secondary particle image 112. On this processed surface, a pseudo analysis image 131 (interpolated image) is created from the secondary particle image 112 without acquiring an analysis image. Further, the next processed cross section is formed by energy beam irradiation. Even on this processed surface, the secondary particle image 113 is acquired, but the analysis image is not acquired, and a pseudo analysis image 132 (interpolated image) is created from the secondary particle image 113. Further, the next processed cross section is formed by energy beam irradiation. On this processed surface, the secondary particle image 114 is acquired, and then the analysis image 122 is also acquired. Hereinafter, similarly, the process of forming a processed surface, acquiring a secondary particle image, acquiring an analysis image, or creating a pseudo analysis image (interpolated image) is repeatedly performed. Then, a three-dimensional reconstructed image is acquired using the analysis image 121, the pseudo analysis image 131 (interpolation image), the pseudo analysis image 132 (interpolation image), the analysis image 122, and the like.

  One of the features of this three-dimensional reconstruction is that the analysis image is simulated based on the secondary particle image acquired on the desired processing surface based on the correlation between the secondary particle image acquired on a certain processing surface and the analysis image. Is to create. Further, it is one of the features that three-dimensional reconstruction is performed using these analysis images and pseudo analysis images (interpolated images).

  In addition, the presence or absence and the number of times of acquisition of the analysis image on each processed surface are not limited and can be arbitrarily selected. Further, the secondary particle image is not limited to the BSE image, and for example, an SE (secondary electron) image may be used. Also, the analysis image for three-dimensional reconstruction is not limited to the EDX mapping image. For example, a WDX (wavelength dispersive X-ray analysis) image or an EBSP (electron beam backscatter diffraction) image is used. Also good.

  In an embodiment, an energy beam optical system for irradiating an energy beam, an electron beam optical system for irradiating an electron beam, a sample stage for placing a sample, and a secondary particle detector for detecting secondary particles generated from the sample And an analyzer for detecting analysis information generated from the sample, the first cross section is formed in the sample by irradiation with the energy beam, and the second generated from the sample by irradiation of the electron beam to the first cross section. Secondary particles and analysis information are detected, a second cross section is formed by irradiation of an energy beam, secondary particles generated from the sample are detected by irradiation of an electron beam to the second cross section, and the first cross section is detected. Disclosed is a charged particle beam device that artificially creates an analysis image of the second cross section from the secondary particle image of the second cross section based on the correlation between the secondary particle image and the analysis image.

  In addition, the embodiment discloses a charged particle beam apparatus that performs three-dimensional reconstruction using at least an analysis image related to the first cross section and a pseudo analysis image related to the second cross section.

  In the embodiment, a charged particle beam device in which the secondary particle detector is a backscattered electron detector is disclosed.

  Moreover, in an Example, the charged particle beam apparatus whose secondary particle detector is a secondary electron detector is disclosed.

  Moreover, in an Example, the analyzer discloses the charged particle beam apparatus which is a detector for EDX.

  Moreover, in an Example, an analyzer discloses the charged particle beam apparatus which is a detector for WDX.

  Moreover, in an Example, an analyzer discloses the charged particle beam apparatus which is a detector for EBSP.

  In the embodiment, a charged particle beam device is disclosed in which the acceleration voltage when irradiating an electron beam onto the second cross section is lower than the acceleration voltage when irradiating the electron beam onto the first cross section.

  Further, in the embodiment, when irradiating the electron beam to the second cross section, a charged particle having an observation condition different from that when the electron beam is applied to the first cross section by applying a retarding voltage to the sample. A wire device is disclosed.

  In addition, the embodiment discloses a charged particle beam apparatus that changes the processing conditions of the energy beam applied to the second cross section based on the analysis image related to the first cross section.

  In the embodiment, the processing conditions of the energy beam are changed based on the secondary particle image relating to the first cross section and the secondary particle image relating to the second cross section, and the third cross section is formed by irradiation of the energy beam. Disclosed is a charged particle beam device to be formed.

  In the embodiment, the secondary particle image and the second cross section relating to the first cross section are determined whether or not the analyzer acquires the analysis information relating to the third cross section formed by the irradiation of the energy beam. Disclosed is a charged particle beam device that makes a determination based on a secondary particle image.

  In addition, the embodiment discloses a charged particle beam device that changes the acquisition condition of the analysis image related to the first cross section based on the secondary particle image related to the first cross section.

  The above and other novel features and effects of the present invention will be described below with reference to the drawings. The drawings are used for understanding the invention and do not limit the scope of rights.

  FIG. 2 is a schematic configuration diagram of the FIB-SEM according to the present embodiment.

  In the FIB-SEM according to the present embodiment, the FIB column 1 that irradiates the focused ion beam is perpendicular to the chamber 6 in which the sample stage 5 is disposed, and the SEM column 2 that irradiates the electron beam is oblique. Has been placed. The arrangement of the FIB column 1 and the SEM column 2 may be reversed. The chamber 6 is also provided with a BSE detector 3 and an EDX detector 4. The inside of the chamber 6 is kept in a vacuum state by an exhaust device (not shown).

  By irradiating the focused ion beam from the FIB column 1, the sample placed on the sample stage 5 is processed to form a cross section for observation. Further, SEM observation is performed by irradiating the cross section with an electron beam from the SEM column 2 and detecting BSE by the BSE detector 3. A secondary electron detector that detects SE may be used instead of the BSE detector. Further, EDX analysis is performed by the EDX analyzer 4 by irradiating the cross section with an electron beam. Instead of an EDX analyzer, an analyzer that measures the composition, properties, structure, or state of a substance, such as a WDX detector or an EBSP detector, may be used.

  FIB column 1, SEM column 2, BSE detector 3, and EDX detector 4 are connected to FIB column controller 11, SEM column controller 21, detector controller 31, and EDX detector controller 41, respectively. It is controlled by each control unit. Each of these control units is connected to the overall apparatus control unit 7 and controls processing observation conditions and timing.

  The overall apparatus control unit 7 executes an input unit for receiving an instruction from the user, an output unit for displaying secondary particle images, analysis images, 3D reconstruction images, and the like, analysis image creation, 3D reconstruction, etc. And a storage unit for storing various algorithms and calculation results. The overall apparatus control unit 7 performs switching control between BSE observation and EDX analysis. The overall apparatus control unit 7 creates a pseudo EDX mapping image based on the BSE image acquired on another processing surface from the correlation between the BSE image acquired on the processing surface with the sample and the EDX mapping image. A three-dimensional reconstruction image can be created from the EDX mapping image and the pseudo EDX mapping image.

  FIG. 2 is an explanatory diagram of the three-dimensional reconstruction algorithm according to the present embodiment.

  The processed surfaces of the sample are the first to fourth four surfaces, the BSE image and the EDX mapping image are acquired on the first processed surface and the fourth processed surface, and the BSE image is acquired on the second processed surface and the third processed surface. Only the case of acquiring will be described.

  In the three-dimensional reconstruction algorithm of the present embodiment, pixel coordinates having a signal of the element of interest are extracted from the EDX mapping image (first Map image) on the first processed surface. You may extract by sampling instead of all the coordinates of a 1st Map image (object). And the brightness | luminance of the 1st BSE image corresponding to this coordinate, for example, average brightness | luminance, is calculated. Next, only luminance coordinates corresponding to the calculated luminance are extracted from the second BSE image. In this case, the calculated luminance may have a certain range. If the overall luminance varies, the luminance profile standard may be used. An EDX mapping image created based on the coordinate information (image) extracted from the second BSE image is stored as a second pseudo EDX mapping image (second interpolation image).

  A third interpolation image is created from the third BSE image by a similar procedure. Note that the third interpolation image may be created afterwards from the correlation information between the fourth BSE image and the fourth Map image instead of the correlation information between the first BSE image and the first Map image. The procedure for creating the third interpolation image from the third BSE image based on the correlation information between the fourth BSE image and the fourth Map image is the step of creating the second interpolation image from the second BSE image based on the correlation between the first BSE image and the first Map image. It is the same as the created procedure.

  A three-dimensional image is reconstructed from the EDX mapping image or pseudo EDX mapping image (first map image, second interpolation image, third interpolation image, and fourth map image) acquired or created in this way.

  According to the present embodiment, it is not necessary to acquire an EDX mapping image (analysis image) that requires a long time for acquisition for each processing surface, and a three-dimensional reconstructed image of the analysis image can be acquired in a shorter time than in the past. Thus, the analysis efficiency can be improved. In addition, damage due to electron beam irradiation can be reduced, and analysis reliability can be improved.

  The present embodiment is an example in the FIB-SEM in which the FIB column and the SEM column are vertically arranged. Hereinafter, the difference from the first embodiment will be mainly described.

  FIG. 4 is a schematic configuration diagram of the FIB-SEM according to the present embodiment.

  In the FIB-SEM according to this example, the FIB column 1 is arranged vertically with respect to the chamber 6 and the SEM column 2 is arranged horizontally. That is, the SEM column 2 is arranged in a direction perpendicular to the FIB column 1. The arrangement of the FIB column 1 and the SEM column 2 may be reversed. According to this arrangement configuration, the electron beam can be vertically incident from the SEM column 2 without moving the sample stage 5 with respect to the processing surface processed by the focused ion beam irradiated from the FIB column 1.

  According to the present embodiment, observation and analysis can be performed with higher accuracy than when the electron beam is incident on the processing surface from an oblique direction. Since drift associated with the driving of the sample stage 5 can be avoided, a highly accurate three-dimensional reconstructed image can be acquired.

  In this embodiment, an analysis image is created from shape information. Hereinafter, the difference from the first and second embodiments will be mainly described.

  FIG. 5 is an explanatory diagram of the three-dimensional reconstruction algorithm according to the present embodiment.

  Similar to Example 1, the processed surfaces of the sample are the first to fourth four surfaces, and the BSE image and the EDX mapping image are obtained on the first processed surface and the fourth processed surface, and the second processed surface and the second processed surface are obtained. A case where only the BSE image is acquired on the three processed surfaces will be described.

  In the three-dimensional reconstruction algorithm of the present embodiment, the shape information of the element of interest and the corresponding pixel coordinates are extracted from the first Map image. Representative pixel coordinates may be extracted. Next, it is determined from the extracted pixel coordinates and shape information whether there is a shape similar to the extracted shape information in the vicinity of the extracted pixel coordinates on the first BSE image. If there is a similar shape, this is estimated as a BSE image of the element of interest. Next, a shape similar to the estimated shape information is extracted from the vicinity of the extracted pixel coordinates on the second BSE image. An EDX mapping image created based on the shape information (image) extracted from the second BSE image is stored as a second interpolation image.

  A third interpolation image is created from the third BSE image by a similar procedure. The third interpolation image may be created afterwards from the correlation information between the fourth BSE image and the fourth Map image instead of the correlation information between the first BSE image and the first Map image, as in the first embodiment. .

  A three-dimensional image is reconstructed from the EDX mapping image or pseudo EDX mapping image (first map image, second interpolation image, third interpolation image, and fourth map image) acquired or created in this way.

  According to the present embodiment, similarly to the first embodiment, there is no need to acquire an analysis image that requires a long time for each processing surface, and a three-dimensional reconstructed image of the analysis image can be acquired in a shorter time than in the past. As a result, the analysis efficiency can be improved. In addition, damage due to electron beam irradiation can be reduced, and analysis reliability can be improved.

  In the present embodiment, the correlation between the secondary particle image on one processing surface and the analysis image is used, and in the three-dimensional reconstruction in which an analysis image is created in a pseudo manner from the secondary particle image on the next processing surface, the tertiary image with higher accuracy The observation conditions are optimized to reconstruct the original image. Hereinafter, it demonstrates centering on difference with Examples 1-3.

  FIG. 6 is a flowchart of the three-dimensional reconstruction algorithm according to the present embodiment.

  In the three-dimensional reconstruction algorithm of the present embodiment, the first cross-section processing is performed by ion beam irradiation. Next, a secondary particle image (BSE image) and an analysis image (EDX mapping image) are acquired by electron beam irradiation on the first processed cross section. The electron beam irradiation during the first cross-sectional observation is performed with the electron beam extraction voltage set to a high acceleration voltage in order to obtain an EDX mapping image. Next, the second cross-section processing and the second cross-section observation are performed. In the second cross-sectional observation, only secondary particle images (BSE images) are acquired. Since it is not necessary to acquire an EDX mapping image during the second cross-sectional observation, the acceleration voltage of the electron beam is lowered. By the low-acceleration electron beam irradiation, the resolution is improved in both the depth direction and the in-plane direction in the second cross-sectional observation. For this reason, a high-resolution image can be formed in the pseudo EDX mapping image created in a pseudo manner from the BSE image of the second processed cross section.

  Note that the same effect can be obtained by applying a retarding voltage by a voltage application mechanism connected to the holder side instead of lowering the acceleration voltage of the electron beam as an observation condition in the second cross-sectional observation.

  According to the present embodiment, a high-resolution pseudo EDX mapping image (analysis image) can be created, and a highly accurate three-dimensional image can be reconstructed from these high-resolution analysis images.

  In this embodiment, the processing conditions for the cross-section processing in the three-dimensional reconstruction in which a pseudo-analysis image is created from the secondary particle image on the next processing surface based on the correlation between the secondary particle image on one processing surface and the analysis image. Is to optimize. Hereinafter, it demonstrates centering around difference with Examples 1-4.

  FIG. 7 is a flowchart of the three-dimensional reconstruction algorithm according to the present embodiment.

  In the three-dimensional reconstruction algorithm of the present embodiment, the first cross-section processing is performed by ion beam irradiation. Next, a secondary particle image (BSE image) and an analysis image (EDX mapping image) are acquired by electron beam irradiation on the first processed cross section. The particle diameter in the EDX mapping image is measured from the acquired EDX mapping image, and the minimum particle diameter (a) is determined. Next, in the second cross-section processing, the processing conditions are changed so that the processing amount by ion beam irradiation is a or less. Thereby, the omission of information from the secondary particle image and the analysis image can be suppressed due to the processing amount being too large.

  According to the present embodiment, since the particle information is reliably captured in the secondary particle image and the analysis image, a three-dimensional image with high information certainty can be reconstructed.

  In this embodiment, the processing conditions for cross-section processing are optimized based on the composition change. Hereinafter, it demonstrates centering around difference with Examples 1-5.

  FIG. 8 is a flowchart of the three-dimensional reconstruction algorithm according to the present embodiment.

  In the three-dimensional reconstruction algorithm of the present embodiment, the first cross-section processing is performed by ion beam irradiation. Next, a secondary particle image (BSE image) and an analysis image (EDX mapping image) are acquired by electron beam irradiation on the first processed cross section. The BSE image at this time is referred to as a BSE image (1). Next, second section processing and second section observation are performed to obtain a BSE image. The BSE image at this time is referred to as a BSE image (2). Then, the brightness of the BSE image (1) and the brightness of the BSE image (2) are compared before performing the third cross-section processing. When the ratio of the luminance of the BSE image (2) to the luminance of the BSE image (1) exceeds a predetermined value α, the composition change in the direction of the processed surface of the material is estimated to be steep, so the third cross-section processing Change the processing conditions so that the amount of processing at that time becomes smaller. In the third cross-sectional observation, the initial schedule is changed and an EDX mapping image is acquired. Thereby, in the observation of the third processed cross section, it is possible to improve the certainty that the information related to the steep composition change is captured.

  According to the present embodiment, composition information is easily captured in the secondary particle image and the analysis image, so that a three-dimensional image with high reliability of information can be reconstructed.

  In this embodiment, the correlation between the secondary particle image and the analysis image on one processing surface is used to obtain the analysis image acquisition conditions in the three-dimensional reconstruction in which the analysis image is pseudo-formed from the secondary particle image on the next processing surface. Is to optimize. Hereinafter, it demonstrates centering around difference with Examples 1-6.

  FIG. 9 is a flowchart of the three-dimensional reconstruction algorithm according to the present embodiment.

  In the three-dimensional reconstruction algorithm of the present embodiment, the first cross-section processing is performed by ion beam irradiation. Next, a secondary particle image (BSE image) is obtained by electron beam irradiation on the first processed cross section. And the particle diameter in a BSE image is measured from the acquired BSE image. If the minimum particle size at this time is smaller than the specified value β, the acquisition conditions for acquiring the EDX mapping image of the same processed cross section are reviewed. For example, the high-resolution acquisition mode is acquired. Thereby, higher information about the correlation between the BSE image and the EDX image can be obtained.

According to the present embodiment, since the correlation between the secondary particle image and the analysis image is increased, a highly accurate three-dimensional image can be reconstructed.

DESCRIPTION OF SYMBOLS 1 ... FIB column 2 ... SEM column 3 ... BSE detector 4 ... EDX analyzer 5 ... Sample stage 6 ... Chamber 7 ... Entire apparatus control part 11 ... FIB column control part 21 ... SEM column control part 31 ... Detector control part 41 ... EDX analyzer control unit 111, 112, 113, 114 ... secondary particle image 121, 122 ... analysis image 131, 132 ... pseudo analysis image

Claims (13)

An energy beam optical system for irradiating the energy beam;
An electron beam optical system for irradiating an electron beam;
A sample stage on which the sample is placed;
A secondary particle detector for detecting secondary particles generated from the sample;
In a charged particle beam apparatus comprising an analyzer for detecting analysis information generated from a sample,
A first cross section is formed on the sample by irradiation with an energy beam, secondary particles generated from the sample and analysis information are detected by irradiation of the electron beam on the first cross section, and a second cross section is detected by irradiation of the energy beam. And detecting the secondary particles generated from the sample by irradiation of the electron beam to the second cross section, and based on the correlation between the secondary particle image and the analysis image of the first cross section, A charged particle beam apparatus characterized in that an analysis image of the second cross section is created in a pseudo manner from a secondary particle image on a cross section.
The charged particle beam apparatus according to claim 1,
A charged particle beam apparatus characterized in that three-dimensional reconstruction is performed using at least an analysis image related to the first cross section and a pseudo analysis image related to the second cross section.
The charged particle beam apparatus according to claim 1,
The charged particle beam apparatus, wherein the secondary particle detector is a backscattered electron detector.
The charged particle beam apparatus according to claim 1,
The charged particle beam apparatus, wherein the secondary particle detector is a secondary electron detector.
The charged particle beam apparatus according to claim 1,
The charged particle beam apparatus, wherein the analyzer is an EDX detector.
The charged particle beam apparatus according to claim 1,
The charged particle beam apparatus, wherein the analyzer is a detector for WDX.
The charged particle beam apparatus according to claim 1,
The charged particle beam apparatus, wherein the analyzer is a detector for EBSP.
The charged particle beam apparatus according to claim 1,
The charged particle beam apparatus characterized by lowering the acceleration voltage when irradiating an electron beam to the said 2nd cross section from the acceleration voltage when irradiating an electron beam to the said 1st cross section.
The charged particle beam apparatus according to claim 1,
When the electron beam is radiated to the second cross section, a charging voltage is applied to the specimen, whereby the observation condition is different from that when the electron beam is radiated to the first cross section. Particle beam device.
The charged particle beam apparatus according to claim 1,
A charged particle beam apparatus, wherein processing conditions of an energy beam applied to the second cross section are changed based on an analysis image related to the first cross section.
The charged particle beam apparatus according to claim 1,
Based on the secondary particle image relating to the first cross section and the secondary particle image relating to the second cross section, the processing conditions of the energy beam are changed, and the third cross section is formed by irradiation of the energy beam. Characterized charged particle beam device.
The charged particle beam apparatus according to claim 1,
The secondary particle image relating to the first cross section and the secondary particle relating to the second cross section are used to determine whether or not the analyzer acquires analysis information relating to the third cross section formed by energy beam irradiation. A charged particle beam apparatus characterized by making a determination based on an image.
The charged particle beam apparatus according to claim 1,
A charged particle beam apparatus characterized by changing an acquisition condition of an analysis image concerning the first section based on a secondary particle image concerning the first section.

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