JP2015141913A - Image processing device and charged particle beam device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image processing device and a charged particle beam device capable of quantitatively evaluating a DSA pattern.SOLUTION: An image processing device comprises an arithmetic device that executes matching processing using a reference image on an acquired image. The arithmetic device generates a reference image on the basis of image extraction from a first region of the acquired image of a sample generated by a self-induction organization process stored in a storage medium, and compares an image in a region of the acquired image other than the first region with the reference image to calculate at least one of the coincidence thereof and position information on a matching position of the reference image.

Description

  The present invention relates to an image processing apparatus and a charged particle beam apparatus, and more particularly to an image processing apparatus and a charged particle beam apparatus suitable for measuring and evaluating a pattern formed by a patterning method using a self-organization phenomenon.

  Semiconductor devices are increasing in scale and integration. Supporting these advances is the microfabrication technology. Among them, the lithography technique has been advanced by shortening the wavelength of the projection exposure apparatus and increasing the NA of the projection lens. However, these are also reaching their limits. In order to overcome such a situation, a technique for multiplying the pattern formed by the projection exposure apparatus by n times has been studied. As such an n-folding method, there is a self-guided organization process, DSA (Directed Self Assembly). This method uses a material in which two types of polymers called polymer block copolymers are synthesized and block-bonded, and is self-organized using the difference in thermodynamic properties of the two types of polymers. It is the method. A plurality of patterns can be formed inside a pattern (guide pattern) formed by lithography, or fine holes can be formed in a self-aligned manner inside large-sized holes.

  On the other hand, with advances in semiconductor device miniaturization processing technology, there have been remarkable advances in evaluation methods and evaluation apparatuses for evaluating the quality of patterns. In Patent Document 1, in a measuring device for measuring the dimension of a pattern, an image of a pattern having a periodicity such as a repetitive pattern is acquired, and the dimension of the pattern is measured based on a signal obtained by integrating the images. A measuring device is described.

International Publication Number WO2013 / 12209

  The pattern formed by the DSA is finally in a state where a plurality of equivalent patterns are arranged, but the guide pattern used for the DSA and the pattern arranged by the self-organization phenomenon between the guide patterns are the manufacturing process. Is different. For example, the position of the pattern arranged by the self-organization phenomenon may change depending on the production of the polymer or guide pattern. In the future, it is expected that there will be a need to perform pattern evaluation according to the polymer and the guide pattern, but conventionally, there has been no discussion about the need for such pattern evaluation. Cited Document 1 describes a method for evaluating a pattern having a periodicity in the same manner as a pattern formed by DSA, but there is no mention or suggestion about evaluating a DSA pattern.

  Hereinafter, an image processing apparatus and a charged particle beam apparatus for the purpose of quantitatively evaluating a DSA pattern will be described.

  As one aspect for achieving the above object, a storage medium for storing an acquired image obtained by scanning with a charged particle beam and a matching process using a reference image on the acquired image stored in the storage medium will be described below. An image processing apparatus or a charged particle beam apparatus including an arithmetic device to be executed, wherein the arithmetic device is a first acquired image of a sample generated by a self-guided organization process stored in the storage medium. An image from a region, a second region corresponding to the first region of the design data of the pattern included in the acquired image, or a third region corresponding to the first region of the simulation image of the design data A reference image is generated based on the extraction, the image of the fourth region of the acquired image other than the first region is compared with the reference image, and the reference image and the fourth region Coincidence of the images, and an image processing apparatus for determining at least one of the position information about the matching position of the reference image, or propose a charged particle beam device.

  According to the said structure, it becomes possible to perform the quantitative evaluation of the pattern formed by a self-guided organization process.

The figure which shows the example which measures the periodic pattern produced | generated by the self-guided organization process. Schematic explanatory diagram of a measurement and inspection system in which a plurality of measurement or inspection devices are connected to a network. The schematic block diagram of a scanning electron microscope. The figure explaining an example of an image processor. The figure which shows the example of an identification display (distribution map) according to the characteristic of a pattern. The figure which shows the example of a display of the result which produced the reference template and compared with each measurement point (image). The figure which shows the example of a display of the measurement result of a hole pattern. The figure explaining the patterning method using a self-organization phenomenon. The figure which shows the example of a measurement of the line pattern formed by self-organization. The figure which shows the example of a measurement of the hole pattern formed by self-organization.

  In the examples described below, the polymer block copolymer obtained by a scanning electron microscope or the like is self-organized on the substrate surface and uses an image of a polymer thin film having a fine structure, and the shape and arrangement thereof are measured. The present invention relates to a method, an apparatus, and a computer program for evaluation. In particular, the present invention relates to a method, an apparatus, and a computer program capable of measuring and evaluating the long-range order and region with respect to periodicity characteristic of a pattern formed by a polymer block copolymer.

  In the manufacturing / inspection process of functional element products such as semiconductor elements and thin film magnetic heads that are manufactured by microfabrication of the surface, scanning pattern width measurement (hereinafter referred to as “measurement”) and visual inspection are used. An electron microscope (Scanning Electron Microscope: SEM) is widely used. A scanning electron microscope emits an electron beam emitted from an electron source and narrowed down by a converging lens and an objective lens using a magnetic field or an interaction between an electric field and an electron beam on a sample using a deflector. The secondary signal (secondary electrons, reflected electrons, and electromagnetic waves) generated from the sample by electron beam irradiation is detected by a detector using the photoelectric effect, and the detection signal is synchronized with the scanning of the electron beam. This is an apparatus for forming a sample image by converting and processing the signal into a visible signal such as a luminance signal.

As a method for finely processing the surface of a semiconductor element, a thin film magnetic head, or the like, a method of forming a pattern with a fine structure such as photolithography or nanoimprint using light, an electron beam, an original plate or the like is generally used. However, as the pattern becomes finer, the process becomes complicated and there are many problems. In particular, when the processing dimension of the fine pattern is reduced to 20 nanometers or less, a huge investment is required for the apparatus.
In recent years, as a method of forming a pattern for microfabrication, a polymer layer containing a polymer block copolymer composition is disposed on a substrate surface, and the polymer layer forms a structure spontaneously by microphase separation. A technique that applies the phenomenon, so-called self-organization phenomenon, is attracting attention. In this method, by optimizing materials and processes, a fine regular structure having various shapes of several nanometers to several hundred nanometers can be formed by a simple coating process.

  As an example of forming a fine regular structure using the self-organization phenomenon, pores and lines regularly arranged using a polymer block copolymer thin film made of polystyrene (PS) and polymethyl methacrylate (PMMA) are used. A known technique in which an andspace pattern is formed on a substrate is known. At this time, the shape of the periodic pattern to be formed (holes or lines and spaces, etc.), the pitch of the periodic arrangement of the shape, the molecular weight, the mixing ratio, etc. of the polymer layer containing the polymer block copolymer composition, etc. Determined by.

  A problem in forming this self-organization on a flat and uniform base is that the range of the regular arrangement is a narrow range of several tens of cycles or less. Moreover, the range of the arrangement | sequence of the different direction has distribution, and a defect exists in the meantime. This range varies depending on the properties of the polymer layer containing the polymer block copolymer composition and the formation process, and a pattern with fewer defects is required over a wider range.

Two methods have been devised in order to make the pattern arrangement formed by self-organization a desired range and to align the arrangement in that range.
The first method is a method of forming a regular array pattern by processing grooves / holes on the surface of the base substrate and forming a polymer layer containing the polymer block copolymer composition therein as a guide. is there. The guide is sized to be about 2 to 10 times the self-organization pattern period so that the arrangement is stable. The microstructure is arranged in a range limited by the guide, and the long-range order of self-organization is improved.

  The second method is a method of chemically patterning the base substrate surface. On the surface of the substrate, regions having different affinities for each block chain constituting the polymer block copolymer are formed as a pattern. For example, in a polymer block copolymer composed of polystyrene and polymethyl methacrylate, a region having a good chemical affinity with polystyrene is about half the self-organization cycle and is twice to ten times the self-assembly cycle. Arrange at a period of about twice. Other regions are chemically formed to have the same affinity as polystyrene and polymethylmethacrylate. The pattern by self-organization of the polymer block copolymer on the surface of this substrate is formed on the guide by using a region having good chemical affinity with polystyrene as a guide. Periodic arrangement from the pattern improves the long-range order of self-organization.

  In the pattern formation by self-organization using the polymer block copolymer thin film as described above, materials and processes have been developed in which regular arrays are arranged in a wide range and defects are reduced. On the other hand, the pattern array formed through the above-described process is formed on a flat and uniform base, and the pattern array is arranged only about a few pitches, and is arranged using a guide for aligning the pattern. May be evenly arranged near the guide.

  The embodiment described below relates to an image processing method and apparatus for measuring and evaluating the range of the same arrangement and the degree of uniformity mainly for the above two types of patterns. The measurement result brought about by such image processing is used for evaluation of the material of the polymer block copolymer thin film, evaluation of a film forming process for each material, and evaluation of a guide forming technique for aligning the alignment.

  As described above, the misregistration between the arrangement pattern formed of the material of the polymer block copolymer thin film and the lower layer pattern is the misregistration (overlay) of the pattern between different layers, which is a problem in the microfabrication process. The influence on the overlay in the pattern formation by self-organization using the polymer block copolymer thin film is not only the overlay of the guide pattern and the lower layer pattern, but also the distribution of the displacement of the relative position of the periodic pattern relative to the guide pattern is important. Become.

  In the embodiment described below, an image processing method for evaluating a method for measuring the displacement of the relative position is proposed.

  As described above, in order to properly evaluate the displacement of the relative position, using the polymer block copolymer thin film, an image of regularly arranged holes and line-and-space is obtained, and a specific region is obtained from the image. At least two locations are selected, images cut out from the two locations are compared, and the coincidence rate is measured. Two images are compared by shifting the relative position within a range equal to or smaller than the pattern cycle size, a relative position shift in which the matching rate between the two images in image processing is maximized is detected, and the matching rate is measured and evaluated.

  When the pattern arrangements of the two specific areas are the same, the degree of coincidence increases. On the other hand, when the pattern arrangements of the two specific regions are different, or when the pattern arrangement is broken in either one, the degree of coincidence is low. Multiple comparisons of specific areas are performed in the image, and the coincidence distribution and array uniformity are measured and evaluated. Further, the size of the specific area to be compared and the distance between the specific areas to be compared are determined using the design data.

  In addition, the reference pattern to be compared and the comparison target image include a guide pattern (first pattern) used for self-guided organization and a pattern (second pattern) formed by the self-guided organization process. By evaluating the degree of coincidence, the degree of deviation between the guide pattern and the pattern formed by self-organization can be expressed by a quantitative evaluation value called the degree of coincidence.

  According to the above configuration, the uniformity and distribution of the pattern arrangement can be measured in the pattern formation by self-assembly using the polymer block copolymer thin film. In the pattern in which the long-range order is improved using the guide, the arrangement of the pattern in the vicinity of the guide and the other patterns can be compared to analyze the distribution of the positional deviation amount between the patterns. Further, optimization of the material and film forming process of the polymer block copolymer thin film used for pattern formation by self-organization, and optimization of the guide forming method and shape can be performed.

  In this example, a technique for measuring mainly the uniformity of the arrangement and the distribution of a pattern produced by pattern formation by self-assembly using a polymer block copolymer thin film will be described.

  The pattern to be measured uses the self-organization phenomenon caused by the polymer layer containing the molecular block copolymer composition, and the pattern arrangement direction and pitch robustness differ depending on the material and formation process. Measurement is important.

  In the following description, a charged particle beam apparatus is exemplified as an apparatus for forming an image, and an example using an SEM is described as one aspect thereof. However, the present invention is not limited to this. For example, an ion beam is formed on a sample. Alternatively, a focused ion beam (FIB) apparatus that forms an image by scanning may be employed as the charged particle beam apparatus. In addition, the type of the imaging device is not limited as long as the distribution of patterns formed by self-organization within the field of view of the captured image can be evaluated based on image processing.

  The principle of the measurement method in this embodiment will be described with reference to FIG. First, an image 101 having a pattern arranged by self-organization using a polymer block copolymer thin film is acquired and stored in a predetermined storage medium. Two specific areas (a first area and two areas including a fourth area) are selected from images stored in the storage medium, and are registered as templates 102 and 103 as two templates. Two templates are compared, and the relative position is shifted by less than the arrangement pitch, and the relative position at which the matching rate between the two images is maximized and the matching rate are measured.

  When the pattern arrangement directions of the two specific areas are the same and uniform in the areas as in the templates 102 and 103, the patterns of the two specific areas have a high pattern matching degree with a relative positional shift equal to or less than the arrangement pitch. When 102 and 104 are selected as templates to be compared, since the arrangement is different in a part of 104, the degree of pattern matching is low. When the templates 102 and 105 are selected, when the relative position shift is only parallel movement, the pattern arrangement of the pattern 105 is different and the pattern matching degree is low. However, when the rotation component is allowed as the relative value deviation, the matching degree is high. When templates 105 and 106 are selected, the arrangement is different from that of 102, but the degree of coincidence between templates 105 and 106 is high. This evaluation is performed between a plurality of specific regions, and the region and uniformity of the same sequence are measured and evaluated from the matching rate.

  By performing the evaluation as described above, it is possible not only to distinguish the region where the polymer is properly arranged from the other regions, but also to quantitatively determine whether the polymer is properly formed (degree of coincidence) And position information such as positional deviation). In addition, by performing a search with rotation while limiting the movement range of the template, all patterns are formed to be inclined, such as an area where some patterns are inclined (for example, the area 104). The region can be identified with high accuracy.

  When the position information is obtained by obtaining a difference between an ideal matching position and an actual matching position, the position where the matching score is maximized or the position where the matching score satisfies a predetermined condition (for example, the matching score) Is a matching position).

  Furthermore, the region in which some patterns are formed in an inclined manner includes a region in which all patterns are properly formed (for example, the region 103) and a region in which patterns are not properly formed (for example, the region 105). Since it is considered that it is located at the boundary, it is possible to accurately identify the area where the pattern is properly formed and the area where the pattern is not formed, and to evaluate the area of the appropriate area, by determining the coincidence with the inclination. It can be said that such a polymer in which a region where a pattern is appropriately formed is formed over a wide range is a polymer suitable for patterning using the DSA method. That is, it is possible to improve the quality of the polymer itself or to maintain the quality by evaluating whether or not the pattern is properly formed in a wide range at the time of polymer preparation or in the quality control of the polymer. Further, the semiconductor device manufacturer can improve or maintain the yield of the semiconductor device by performing the above evaluation.

  Since the merit of this method is compared in the acquired image, it is not necessary to acquire a reference image in advance. This is because the pattern has a pattern arrangement and period determined by the mixing ratio of the material to be evaluated. The size of the specific area is 2 to several tens of pitches of the arrangement period, and the distance between the specific areas to be compared is equal to or greater than the arrangement pitch. If there is, it is possible to evaluate. If the pitch is less than the arrangement pitch, the degree of coincidence becomes maximum at the position where the two comparison images overlap, and the arrangement distribution cannot be evaluated.

  In addition, when a guide pattern is prepared and patterning based on self-guided organization is performed, the guide pattern (first pattern) and the pattern formed by the self-guided organization process (second pattern) are included. By preparing a reference image and evaluating the degree of coincidence and the like, it is possible to relatively evaluate the performance of the DSA pattern according to the performance of the guide pattern. By preparing a reference image including both the first pattern and the second pattern, the degree of deviation can be expressed by a quantitative index value such as the degree of coincidence or positional deviation. It is possible to accurately perform the relative evaluation.

  FIG. 2 is a schematic explanatory diagram of a measurement / inspection system in which a plurality of measurement or inspection devices are connected to a network. The system has a configuration in which SEMs 201, 202, and 203 that mainly measure or inspect pattern dimensions of semiconductor wafers, photomasks, and the like are connected to a network. The network also functions as an image processing apparatus that sets measurement positions, measurement conditions, etc. on semiconductor device design data, and performs measurements and inspections based on the obtained SEM images. A condition setting device 204, a semiconductor device design data, a simulator 205 for simulating the performance of the pattern based on the manufacturing conditions of the semiconductor manufacturing device, and the layout data of the semiconductor device A storage medium 206 for storing design data in which manufacturing conditions are registered is connected.

  The design data is expressed in, for example, the GDS format or OASIS format, and is stored in a predetermined format. The design data may be of any type as long as the software that displays the design data can display the format format and can handle it as graphic data. Further, the storage medium 206 may be built in the measuring device, the control device of the inspection device, the condition setting device 204, or the simulator 205. The simulator 205 has a function of simulating the defect occurrence position based on the design data.

The SEMs 201, 202, and 203 are provided with respective control devices, and control necessary for each device is performed. These control devices are provided with setting functions such as the function of the simulator and measurement conditions. You may make it mount.
In SEM, an electron beam emitted from an electron source is focused by a plurality of stages of lenses, and the focused electron beam is one-dimensionally or two-dimensionally formed on a sample by a scanning deflector. Scanned.

  Secondary electrons (SE) or back scattered electrons (BSE) emitted from the sample by scanning the electron beam are detected by the detector and synchronized with the scanning deflector scanning. And stored in a storage medium such as a frame memory. The image signals stored in the frame memory are integrated by an arithmetic device mounted in the control device. Further, scanning by the scanning deflector is possible for any size, position, and direction.

  The above control and the like are performed by the control devices of each SEM, and images and signals obtained as a result of scanning the electronic beam are sent to the condition setting device 204 via the communication line network. . In this example, the control device for controlling the SEM and the condition setting device 204 are described as separate units. However, the present invention is not limited to this, and the control and measurement of the device are performed by the condition setting device 204. Processing may be performed in a lump, or SEM control and measurement processing may be performed together in each control device.

  The condition setting device 204 or the control device stores a program for executing a measurement process, and performs measurement or calculation according to the program.

  The condition setting device 204 has a function of creating a program (recipe) for controlling the operation of the SEM based on semiconductor design data, and functions as a recipe setting unit. Specifically, desired measurement points, autofocus, autostigma, addressing points, etc. on design data, pattern outline data, or design data that has been simulated A position for performing processing necessary for the SEM is set, and a program for automatically controlling the sample stage, deflector, etc. of the SEM is created based on the setting.

  In the description of the first embodiment, an example is described in which a template is extracted from acquired images acquired by the SEMs 201, 202, 203, and the like, and the same image as the image from which the template is extracted is used as a search target image for template matching. However, the template is contour data (contour image: second region) formed based on the design data stored in the storage medium 206, or a simulation image (third region) output by the simulator 205. There may be.

  FIG. 3 is a schematic configuration diagram of a scanning electron microscope. An electron beam 303 extracted from the electron source 301 by the extraction electrode 302 and accelerated by an accelerating electrode (not shown) is squeezed by a condenser lens 304 which is a form of a focusing lens, and then is scanned by a scanning deflector 305. 309 is scanned one-dimensionally or two-dimensionally. The electron beam 303 is decelerated by a negative voltage applied to an electrode built in the sample stage 308 and is focused by the lens action of the objective lens 306 and irradiated onto the sample 309.

  When the electron beam 303 is irradiated onto the sample 309, electrons 310 such as secondary electrons and backscattered electrons are emitted from the irradiated portion. The emitted electrons 310 are accelerated in the direction of the electron source by the acceleration action based on the negative voltage applied to the sample, and collide with the conversion electrode 312 to generate secondary electrons 311. The secondary electrons 311 emitted from the conversion electrode 312 are captured by the detector 313, and the output of the detector 313 changes depending on the amount of captured secondary electrons.

  In accordance with this output, the brightness of a display device (not shown) changes. For example, when a two-dimensional image is formed, an image of the scanning region is formed by synchronizing the deflection signal to the scanning deflector 305 and the output of the detector 313. Further, the scanning electron microscope illustrated in FIG. 8 includes a deflector (not shown) that moves the scanning region of the electron beam. This deflector is used to form images of patterns having the same shape existing at different positions. This deflector is also called an image shift deflector, and enables movement of the field of view (Field of View: FOV) position of the electron microscope without moving the sample by the sample stage. The image shift deflector and the scanning deflector may be a common deflector, and the image shift signal and the scanning signal may be superimposed and supplied to the deflector.

  In the example of FIG. 3, an example is described in which electrons emitted from the sample are converted by the conversion electrode and detected. However, the present invention is not limited to such a configuration. It is possible to adopt a configuration in which the detection surface of the electron multiplier tube or the detector is arranged on the orbit.

  The control device 314 controls each component of the scanning electron microscope, and forms a pattern based on the detected electrons and a pattern formed on the sample based on the detected electron intensity distribution called a line profile. -It has a function to measure the size.

  An image processor 401 (arithmetic unit) illustrated in FIG. 4 includes a comparison calculation area setting unit 402, a template setting unit 403, a pattern matching setting unit 404, a pattern matching rate calculation unit 405, a pattern arrangement and defect distribution storage unit 406, a template. A storage unit 407 and a measurement result storage unit 408 are provided.

  The comparison calculation area setting unit 402 sets a combination to be compared with a plurality of specific areas to be compared in an image based on an input or a preset condition. The template setting unit 403 creates a template by cutting out a part of an image obtained by a scanning electron microscope, design data, and a part of a pattern image obtained from an exposure simulator. The template created by the template setting unit 403 is stored in the template storage unit 408 or the recipe storage unit.

  The pattern matching execution unit 404 executes pattern matching based on the plurality of templates created by the template setting unit 403. Template matching specifies a relative position where the shapes of two templates to be compared match, and specifies a relative position where the degree of matching is maximized by using a normalized correlation, a phase-only correlation, or the like. It is a technique. The relative position may include only parallel movement or may include rotational components. When there is a defect in one of the templates to be compared or when the arrangement is different, the matching degree is low even at the relative position where the matching degree is maximum. The pattern matching degree calculation unit 405 calculates the matching degree of the compared templates.

  The pattern arrangement and defect distribution calculation unit 406 calculates the pattern arrangement and defect distribution from the relative positional deviation amount specifically inserted by pattern matching and the degree of coincidence distribution.

  Note that the image processor 401 may be integrated with the SEM control device, or may be a separate image processing device from the SEM connected to the SEM via a network.

  As described above, FIG. 5 shows a distribution display example of the quality evaluation results of patterns of a plurality of regions on an image using a template. Based on the periodic pattern 501 by self-organization, a display such as a pattern arrangement display 502 is performed. In the pattern arrangement display 502, identification display according to the pattern state for each region is performed. For example, a measurement point 503 in which the pattern arrangement around each evaluation point is aligned with the adjacent pattern is indicated by ◯, and a measurement point 504 that is not aligned or has a defect is indicated by ×. The quality of the pattern arrangement can be determined by the ratio of the number of circles to the evaluated measurement points.

  According to the display such as the orientation pattern display 505, the measurement points 506 in which the pattern arrangement around each evaluation point is aligned with the adjacent pattern can be displayed as a vector including the arrangement direction. In the pattern arrangement display 507, only the aligned area can be determined, and the area of the region 508 where the pattern arrangement is constant can be analyzed.

  As described above, since the direction of the pattern is appropriate and the area of the aligned region is larger, the polymer is a polymer that is more suitable for patterning using the DSA method. Thus, by determining the area of the identified region, it is possible to evaluate the polymer used for patterning using the DSA method. In addition, even if it is other than an area, if it is an index value which shows the magnitude | size of an area | region, the kind will not ask | require. For example, other index values related to the area such as the number of ○ (or ×) in the pattern array display 502 and the ratio of the area of the appropriate (or inappropriate) area to the entire area may be used. By calculating an index value related to the area using the image processor 401, it is possible to quantitatively evaluate the result of the polymer.

  FIG. 6 shows an example in which one of the two templates to be compared is a reference template and the result of comparison with a template cut out from the vicinity of each measurement point is the measurement value of the measurement point.

  With respect to the periodic pattern 601 by self-organization, templates 606, 607, and 608 that are cut out to be larger than the period of the periodic pattern, including the periphery when cutting out from the specific regions 603, 604, and 605, are synthesized. Generate. The reason why the templates 606, 607, and 608 are cut out larger is that the relative positions of the templates may be shifted in the range of the pitch of each periodic pattern. In addition, a reference template (reference image) is generated.

  As a method for generating a reference template, there is also a method in which a specific region is cut out from the design data 610 of the periodic pattern 601 by self-organization to form a template 311. Compared to the generated reference template and a template cut out from the specific regions 603, 604, and 605 centered on the measurement point 602, the coincidence rate, relative positional deviation, and array direction are measured, and the distribution is calculated.

  According to the processing as described above, it is possible to grasp the distribution of evaluation results for each measurement point 602. Note that the partial area 611 may be cut out from the design data 601 and used as a template.

  In Example 1, although the example which performs the measurement for the material used when creating the line pattern by arranging the polymers in a straight line has been described, in this example, the measurement for the hole pattern is performed. An example of performing is described. An example of an SEM image of a sample in which a plurality of hole patterns are arranged is shown in FIG.

  First, a hole pattern image 701 including a plurality of hole patterns 702 arranged by self-assembly using a polymer block copolymer thin film is acquired. Next, a specific area of the image, an image formed based on the pitch determined by the material, or design data is imaged (converted from vector data to layout data), and the area corresponding to the specific area from the image Is registered as a template 703. The shape of the template is arbitrary, but a hexagon like the template 703 is a unit of the pattern period. A measurement point is set in the image, a relative positional deviation including a rotation component having a high coincidence rate with this reference template is obtained, areas having the same rotation angle are determined as the same periodic pattern, and each area and defect area 704 are determined. Define

  Further, in the case of the hole pattern arranged as shown in FIG. 7, instead of a hexagon, a triangle may be selectively cut out as a template. In the case of a triangular template, it is preferable to evaluate the pattern arrangement condition of the image 701 by moving the template with rotation. In addition, since the arrangement pattern by self-organization includes a rectangle such as a rectangle, a square, a diamond, and a parallelogram, a template may be extracted in units of such basic figures.

  As described above, it is possible to evaluate the process conditions for self-organization and the polymer by extracting the template in units of patterns constituting the polygon and extracting the degree of coincidence and position information. .

  A pattern arrangement formed by self-organization is set as a desired range, an alignment guide for aligning the arrangement of the range is formed, and a polymer block copolymer made of polystyrene (PS) and polymethyl methacrylate (PMMA) is used 2 An example of one process flow is shown in FIG.

  The first example is an example in which a groove is used as a guide. A neutral layer 802 having the same affinity for the PS phase and the PMMA phase is formed on the surface of the base substrate 801, and an HSQ resist pattern 803 is formed thereon by a lithography technique. Next, using this HSQ resist pattern 803 as an alignment guide for polymer block copolymerization, a lamellar structure comprising an alternating laminated structure of PS phase 804 and PMMA phase 805 of polymer block copolymerization is formed. At this time, since the surface of the HSQ resist 803 has affinity for the PMMA phase, the PMMA phase 805 is formed on the surface of the guide sidewall. Finally, the PMMA phase 805 is selectively etched to form line patterns of the HSQ resist pattern 803 and the PS phase 804.

The space of the HSQ resist pattern 803 is set to be the period of the alternately laminated structure of the PS phase 804 and the PMMA phase 805 + one-half of the periphery thereof. In the example shown in the figure, the cycle is 2 and 1/2, and two line patterns of the PS phase 804 are formed in the space of the HSQ resist pattern 803. The second example guides a chemically patterned substrate. It is a method. An antireflection film 806 and a layer 807 having an affinity for the PS phase are formed on the base substrate 806, a resist pattern 809 is formed by lithography, and the layer having an affinity for the PS phase by using the resist pattern 809 as a mask 807 is etched to form a line having affinity for the PS phase to form an alignment guide 810 for polymer block copolymerization. Next, a neutral layer 811 having the same affinity for the PS phase and the PMMA phase is formed between the lines 810 having an affinity for the PS phase, and the PS phase 812 and PMMA of the polymer block copolymer are formed thereon. A lamellar structure composed of alternately laminated structures of phases 813 is formed. At this time, the PS phase 812 having a lamellar structure can be segregated on the alignment guide 810.

  Finally, the PMMA phase 812 is selectively etched to form a PS phase 812 line pattern. The pitch of the line 810 having affinity for the PS phase is an integral multiple of the period of the alternately laminated structure of the PS phase 804 and the PMMA phase 805, and is three times the period in the illustrated example. Lines formed from the PS phase 812 include a PS phase line 816 on the alignment guide 814 and a PS phase line 817 on the neutral layer 815. There are concerns that the roughness and cross-sectional structure of the two types of lines are different.

  FIG. 9 shows an example of measurement of the line pattern formed by the process illustrated in FIG. In the design data 901, guide patterns are arranged at a pitch three times that of a line pattern formed by self-organization. That is, the design data 901 includes line data 902 on the guide and line data 903 not on the guide. Here, an example in which the degree of pattern arrangement is quantified using a specific area 904 having a size approximately equal to the pattern pitch will be described.

  When the pattern 905 formed by self-organization of the design data 901 is measured, when the line pattern 906 on the guide is compared with the line pattern 907 that is not on the guide, the shift amount of the pattern edge from the position of the design data is different.

  For example, when the specific areas 908 and 909 including the on-guide line pattern are compared with the specific areas 910 and 911 including the line pattern not on the guide, respectively, the template matching rate extracted from the specific areas 908 and 909 including the on-guide line pattern Is expensive.

  In addition, if the average pitch of the pattern is obtained from the spatial frequency of the entire pattern or the average of the line pitch, and the interval between the specific areas matches the period of the line arrangement, the deviation between the templates from each specific area is determined. In the case of comparison between line patterns on the guide, the relative positional deviation amount is minimized. By obtaining the distribution of the positional deviation accuracy of the line pattern, the degree of positional deviation from the design data of the line pattern can be quantified. There is also a method of improving accuracy by performing a smoothing process on an image pattern in order to remove the influence of image noise.

  Next, a measurement example of a hole pattern formed by the DSA method will be described. The design data 1001 is an example in which the arrangement is aligned using a guide pattern three times the hole pitch. It consists of hole data 1002 on the guide and hole data 1003 not on the guide. Here, an example in which the degree of pattern arrangement is quantified using a specific region 1004 having the same size as the pattern pitch will be described.

  When measuring the pattern 1005 formed by the self-organization of the design data 1001, the average pitch of the pattern is obtained from the spatial frequency of the entire pattern or the average of the pole pitch for the arrangement of the specific area, and the interval between the specific areas is determined as the period of the line arrangement , The relative displacement between the templates from each specific region is minimized when comparing the hole patterns on the guide. For example, when comparing the specific regions 1006 and 1007 including the hole pattern on the guide with the specific regions 1008 including the hole pattern not on the guide, the template cut out from the specific regions 1006 and 1007 including the hole pattern on the guide has a matching rate. high. Further, by obtaining the distribution of the positional deviation accuracy of the hole pattern, the degree of positional deviation from the design data of the hole pattern can be quantified.

101 Images 102, 103, 104, 105, 106 of patterns arranged by self-organization Templates 201, 202, 203 SEM cut out from specific areas
204 Condition setting device 205 Simulator 206 Storage medium 301 Electron source 302 Extraction electrode 303 Electron beam 304 Condenser lens 305 Scanning deflector 306 Objective lens 307 Sample chamber 309 Sample stage 309 Sample 310 Electron 311 Secondary electron 312 Conversion electrode 313 Detector 314 Control Device 401 Image processor 402 Comparison calculation area setting unit 403 Template setting unit 404 Pattern matching setting unit 405 Pattern matching rate calculation unit 406 Pattern arrangement and defect distribution storage unit 407 Template storage unit 408 Measurement result storage unit 501 Periodic pattern by self-organization 502 Pattern arrangement display 503 Display of measurement points aligned with adjacent pattern 504 Display of measurement points not aligned with adjacent pattern or defective 505 Orientation pattern display 506 Vector display 507 of measurement points aligned with adjacent patterns 507 Pattern array display 507
508 Area where pattern arrangement is constant 601 Periodic pattern 602 by self-organization Measurement points 603, 604, 605 Specific areas 606, 607, 608 Template +
609 Reference template 610 Design data 611 Reference template 701 cut out from specific area of design data Image 702 of hole pattern arranged by self-organization Measurement point 703 Reference template 704 Same periodic pattern area and defect area 801 Base substrate 802 PS phase and Neutral layer 803 having the same affinity for PMMA phase HSQ resist pattern 804 PS phase 805 of polymer block copolymer PMMA phase 806 of polymer block copolymer Under substrate 807 Antireflection film 808 Layer having affinity for PS phase 809 Resist pattern 810 Line 811 having affinity for PS phase Neutral layer 812 having the same affinity for PS phase and PMMA phase PS phase 813 of polymer block copolymer PMMA phase 814 of polymer block copolymer Alignment guide 8 5 Neutral layer 816 PS phase line 817 on the alignment guide PS phase line 901 on the neutral layer Design data 902 Line data on the guide 903 Line data not on the guide 904 Specific region 905 having the same size as the pattern pitch 905 Self Pattern 906 formed by organization Line pattern 907 on guide Line pattern 908 not on guide 908, 909 Specific area 910 including line pattern on guide, 911 Specific area including line pattern not on guide 1001 Design data 1002 On guide Hole data 1003 of the hole data 1004 not on the guide The specific area 1005 having the same size as the pattern pitch 1005, patterns 1006 and 1007 formed by self-organization The specific area 1008 including the hole pattern on the guide Specific region including the hole pattern

Claims (13)

In an image processing apparatus comprising: a storage medium that stores an acquired image obtained by scanning a charged particle beam; and an arithmetic unit that executes a matching process using a reference image on the acquired image stored in the storage medium.
The arithmetic device corresponds to a first region of the acquired image of the sample generated by a self-guided organization process stored in the storage medium, and the first region of design data of a pattern included in the acquired image A reference image is generated on the basis of extraction of an image from a second region or a third region corresponding to the first region of the simulation image of the design data, and the acquired image other than the first region The image of the fourth area is compared with the reference image, and at least one of the degree of coincidence between the reference image and the image of the fourth area and the position information regarding the matching position of the reference image is obtained. An image processing apparatus. In claim 1,
The arithmetic device determines at least one of a degree of coincidence with the reference image and position information regarding a matching position of the reference image in a plurality of regions having different positions of the acquired image. In claim 2,
The image processing device is characterized in that the arithmetic device obtains at least one of the degree of coincidence and position information within a predetermined range of a plurality of regions having different positions of the acquired image. In claim 3,
The said arithmetic unit is an image processing apparatus characterized by performing a matching process, rotating the said reference image within the predetermined range of several area | regions from which the position of the said acquired image differs. In claim 4,
The image processing apparatus is characterized in that the arithmetic device identifies a plurality of regions in the acquired image according to a degree of rotation of the reference image. In claim 5,
An image processing apparatus comprising: a display device that identifies and displays a plurality of regions in the acquired image. In claim 1,
The arithmetic device identifies a plurality of regions in the acquired image according to at least one of a degree of coincidence between the reference image and the image of the fourth region and position information of a matching position. Image processing device. In claim 7,
An image processing apparatus comprising: a display device that identifies and displays a plurality of regions in the acquired image. In claim 1,
The image processing device is characterized in that the arithmetic device combines the images extracted from a plurality of regions of the acquired image to generate the reference image. In claim 1,
The arithmetic processing device calculates a relative position between a guide pattern included in the sample and a pattern generated by self-organization. In claim 1,
The image processing apparatus is characterized in that the arithmetic device calculates a relative displacement distribution from design data of a pattern in a periodic array of images from an average position of pattern edge points and a pattern average period. In claim 1,
The image processing apparatus is characterized in that the arithmetic device obtains information on an area of an area where at least one of the degree of coincidence and position information satisfies a predetermined condition. A deflector that scans a beam emitted from a charged particle source, a detector that detects charged particles obtained by beam scanning of the deflector, and an acquired image formed on the basis of a signal obtained by the detector In the charged particle beam apparatus equipped with an arithmetic unit that executes a matching process using a reference image in
The arithmetic device corresponds to a first region of the acquired image of the sample generated by a self-guided organization process stored in the storage medium, and the first region of design data of a pattern included in the acquired image A reference image is generated on the basis of extraction of an image from a second region or a third region corresponding to the first region of the simulation image of the design data, and the acquired image other than the first region The image of the fourth area is compared with the reference image, and at least one of the degree of coincidence between the reference image and the image of the fourth area and the position information regarding the matching position of the reference image is obtained. A charged particle beam device.