WO2020121739A1 - 画像マッチング方法、および画像マッチング処理を実行するための演算システム - Google Patents
画像マッチング方法、および画像マッチング処理を実行するための演算システム Download PDFInfo
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T7/00—Image analysis
- G06T7/30—Determination of transform parameters for the alignment of images, i.e. image registration
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/30—Circuit design
- G06F30/39—Circuit design at the physical level
- G06F30/398—Design verification or optimisation, e.g. using design rule check [DRC], layout versus schematics [LVS] or finite element methods [FEM]
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
- G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
- G06F3/048—Interaction techniques based on graphical user interfaces [GUI]
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
- G01N23/02—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material
- G01N23/06—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and measuring the absorption
- G01N23/18—Investigating the presence of flaws defects or foreign matter
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F18/00—Pattern recognition
- G06F18/20—Analysing
- G06F18/22—Matching criteria, e.g. proximity measures
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/20—Design optimisation, verification or simulation
- G06F30/27—Design optimisation, verification or simulation using machine learning, e.g. artificial intelligence, neural networks, support vector machines [SVM] or training a model
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06N—COMPUTING ARRANGEMENTS BASED ON SPECIFIC COMPUTATIONAL MODELS
- G06N20/00—Machine learning
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T7/00—Image analysis
- G06T7/0002—Inspection of images, e.g. flaw detection
- G06T7/0004—Industrial image inspection
- G06T7/001—Industrial image inspection using an image reference approach
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B15/00—Measuring arrangements characterised by the use of electromagnetic waves or particle radiation, e.g. by the use of microwaves, X-rays, gamma rays or electrons
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
- G01N23/22—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material
- G01N23/225—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material using electron or ion
- G01N23/2251—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material using electron or ion using incident electron beams, e.g. scanning electron microscopy [SEM]
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T2207/00—Indexing scheme for image analysis or image enhancement
- G06T2207/20—Special algorithmic details
- G06T2207/20081—Training; Learning
Definitions
- the present invention relates to an image matching process for aligning a pattern on design data with a pattern on an image, and particularly to an image matching process using a model constructed by machine learning.
- a pattern inspection method for semiconductor devices using die-to-database technology is known (for example, Patent Document 1).
- a typical pattern inspection method is to generate an image of a pattern on a wafer with a scanning electron microscope, compare a CAD pattern on design data (also referred to as CAD data) with a pattern on the image, and check the pattern on the wafer. Detecting defects.
- a pre-process of such a pattern inspection method a matching process for aligning the CAD pattern on the design data with the pattern on the image is performed.
- FIG. 13 is a schematic diagram showing an example of matching processing.
- the CAD pattern 501 on the design data is compared with each of a number of patterns 505-1 to 505-N in a certain area on the image, and the pattern 505-which is the closest to the shape of the CAD pattern 501.
- the algorithm of determining n is executed.
- the above-described matching processing requires a long processing time because it is necessary to compare the CAD pattern 501 with many patterns 505-1 to 505-N on the image. Further, the pattern 505-n on the image corresponding to the CAD pattern 501 is deformed in the step of forming the pattern on the wafer and/or the step of imaging the pattern on the wafer. Therefore, as shown in FIG. 14, there is a large difference in shape between the CAD pattern 501 and the pattern 505-n. As a result, the matching process sometimes failed.
- the present invention provides a method and apparatus capable of correctly performing a matching process between a CAD pattern on design data and a corresponding pattern on an image.
- a specified CAD pattern on design data is converted into a CAD image
- the CAD image is input to a model constructed by machine learning, and calculation is performed according to an algorithm defined by the model.
- a method of outputting a pseudo image from the model, and determining a pattern having a shape closest to the shape of the CAD pattern on the pseudo image from a plurality of patterns on the image generated by an image generation device is provided. It
- the model includes training data including at least a plurality of CAD images converted from a plurality of CAD patterns on design data and a plurality of images generated by an image generation device corresponding to the plurality of CAD images. Is a model constructed by machine learning using.
- the training data further includes training additional information data, and the training additional information data is converted from position information of the plurality of CAD patterns and a plurality of CAD patterns around the plurality of CAD patterns. At least one of the plurality of peripheral images and the plurality of layer images converted from the plurality of CAD patterns existing above or below the plurality of CAD patterns.
- additional information data is input to the model, and the additional information data is obtained from position information of the designated CAD pattern and CAD patterns around the designated CAD pattern. At least one of the transformed peripheral image and the layer image transformed from the CAD pattern existing above or below the specified CAD pattern is included.
- the method comprises machine learning so that the CAD pattern on the pseudo image output from the model matches a corresponding pattern on the image generated by the image generation device within a predetermined tolerance. And adjusting the parameters of the model.
- a computing system for executing an image matching process comprising a storage device that stores a model constructed by machine learning and a program, and a processing device that performs a computation according to the program,
- the system converts a specified CAD pattern on the design data into a CAD image, inputs the CAD image into the model, and executes a calculation according to an algorithm defined by the model to generate a pseudo image from the model.
- An arithmetic system is provided that operates so as to determine a pattern having a shape that is closest to the shape of a CAD pattern on the pseudo image from among a plurality of patterns on an image generated by an image generation device. ..
- the model includes training data including at least a plurality of CAD images converted from a plurality of CAD patterns on design data and a plurality of images generated by an image generation device corresponding to the plurality of CAD images. Is a model constructed by machine learning using.
- the training data further includes training additional information data, and the training additional information data is converted from position information of the plurality of CAD patterns and a plurality of CAD patterns around the plurality of CAD patterns. At least one of the plurality of peripheral images and the plurality of layer images converted from the plurality of CAD patterns existing above or below the plurality of CAD patterns.
- additional information data is input to the model, and the additional information data includes positional information of the designated CAD pattern and CAD patterns around the designated CAD pattern. At least one of the transformed peripheral image and the layer image transformed from the CAD pattern existing above or below the specified CAD pattern is included.
- the computing system is configured to match the CAD pattern on the pseudo image output from the model with a corresponding tolerance pattern on the image generated by the image generation device within a predetermined tolerance. It operates to perform learning and adjust the parameters of the model.
- a computing system for executing an image matching process comprising a storage device that stores a model constructed by machine learning and a program, and a processing device that performs a computation according to the program, Is a method of converting a specified CAD pattern on design data into a CAD image, inputting the CAD image into the model, and executing calculation according to an algorithm defined by the model, The step of outputting a pseudo image, and the step of determining a pattern having a shape closest to the shape of the CAD pattern on the pseudo image from the plurality of patterns on the image generated by the image generating apparatus are provided to the arithmetic system.
- a computing system is provided that includes instructions for execution.
- the model constructed by machine learning such as deep learning can accurately predict the actual pattern from the CAD pattern on the design data. That is, the CAD pattern that appears on the pseudo image output from the model is expected to have a shape close to the actual pattern. Therefore, the arithmetic system can correctly align the CAD pattern on the pseudo image with the pattern on the image generated by the image generation device (that is, image matching processing).
- FIG. 9 is a flowchart illustrating an embodiment of building a model by machine learning. It is a schematic diagram which shows an example of the CAD image converted from the CAD pattern. It is a schematic diagram which shows an example of the SEM image produced
- FIG. 1 is a schematic diagram showing an embodiment of an imaging device.
- the image pickup apparatus includes a scanning electron microscope 50 and a calculation system 150.
- the scanning electron microscope 50 is an example of an image generation device.
- the scanning electron microscope 50 is connected to the arithmetic system 150, and the operation of the scanning electron microscope 50 is controlled by the arithmetic system 150.
- the computing system 150 includes a storage device 162 in which a database 161 and a program are stored, and a processing device 163 that executes a computation according to the program.
- the processing device 163 includes a CPU (central processing unit) or GPU (graphic processing unit) that performs an operation according to a program stored in the storage device 162.
- the storage device 162 includes a main storage device (eg, random access memory) accessible by the processing device 163 and an auxiliary storage device (eg, hard disk drive or solid state drive) for storing data and programs.
- the computing system 150 includes at least one computer.
- the computing system 150 may be an edge server connected to the scanning electron microscope 50 by a communication line, or a cloud server connected to the scanning electron microscope 50 by a network such as the Internet, or It may be a fog computing device (gateway, fog server, router, etc.) installed in a network connected to the scanning electron microscope 50.
- the computing system 150 may be a combination of multiple servers.
- the computing system 150 may be a combination of an edge server and a cloud server connected to each other by a network such as the Internet.
- the scanning electron microscope 50 includes an electron gun 111 that emits an electron beam composed of primary electrons (charged particles), a focusing lens 112 that focuses the electron beam emitted from the electron gun 111, and an X deflector that deflects the electron beam in the X direction. 113, a Y deflector 114 for deflecting the electron beam in the Y direction, and an objective lens 115 for focusing the electron beam on a wafer 124 as a sample.
- an electron gun 111 that emits an electron beam composed of primary electrons (charged particles)
- a focusing lens 112 that focuses the electron beam emitted from the electron gun 111
- an X deflector that deflects the electron beam in the X direction.
- a Y deflector 114 for deflecting the electron beam in the Y direction
- an objective lens 115 for focusing the electron beam on a wafer 124 as a sample.
- the focusing lens 112 and the objective lens 115 are connected to the lens controller 116, and the operations of the focusing lens 112 and the objective lens 115 are controlled by the lens controller 116.
- the lens controller 116 is connected to the arithmetic system 150.
- the X deflector 113 and the Y deflector 114 are connected to the deflection control device 117, and the deflection operations of the X deflector 113 and the Y deflector 114 are controlled by the deflection control device 117.
- This deflection control device 117 is also connected to the arithmetic system 150.
- the secondary electron detector 130 and the backscattered electron detector 131 are connected to the image acquisition device 118.
- the image acquisition device 118 is configured to convert the output signals of the secondary electron detector 130 and the backscattered electron detector 131 into an image.
- the image acquisition device 118 is similarly connected to the arithmetic system 150.
- the sample stage 121 arranged in the sample chamber 120 is connected to the stage controller 122, and the position of the sample stage 121 is controlled by the stage controller 122.
- the stage controller 122 is connected to the arithmetic system 150.
- a wafer transfer device 140 for mounting the wafer 124 on the sample stage 121 in the sample chamber 120 is also connected to the arithmetic system 150.
- the electron beam emitted from the electron gun 111 is focused by a focusing lens 112, then is focused by an objective lens 115 while being deflected by an X deflector 113 and a Y deflector 114, and is irradiated on the surface of a wafer 124.
- a focusing lens 112 When the wafer 124 is irradiated with primary electrons of the electron beam, secondary electrons and reflected electrons are emitted from the wafer 124. Secondary electrons are detected by the secondary electron detector 130, and reflected electrons are detected by the reflected electron detector 131.
- the detected secondary electron signal and the reflected electron signal are input to the image acquisition device 118 and converted into an image. The image is transmitted to the computing system 150.
- the design data of the wafer 124 is stored in the storage device 162 in advance.
- the design data of the wafer 124 includes pattern design information such as the coordinates of the vertices of the pattern formed on the wafer 124, the position, shape, and size of the pattern, and the layer number to which the pattern belongs.
- a database 161 is built in the storage device 162.
- the design data of the wafer 124 is stored in the database 161 in advance.
- the arithmetic system 150 can read the design data of the wafer 124 from the database 161 stored in the storage device 162.
- the matching process is divided into a step of constructing a model by machine learning and a step of performing alignment (that is, image matching processing) between a CAD pattern on a pseudo image generated using the model and a pattern on an SEM image. Be done.
- the model construction and the image matching process are executed by the arithmetic system 150.
- the computing system 150 includes at least one dedicated computer or general-purpose computer.
- the first computer executes the step of building the model, and the second computer uses the model to perform CAD on the pseudo image. Alignment of the pattern with the pattern on the SEM image may be performed.
- the model created by the first computer may be temporarily stored in a semiconductor memory such as a USB flash drive (also referred to as a USB memory) and then read from the semiconductor memory into the second computer.
- the model created on the first computer may be sent to the second computer over a communication network such as the Internet or a local area network.
- FIG. 2 is a flowchart illustrating an embodiment of building a model by machine learning.
- the arithmetic system 150 specifies the CAD pattern on the design data.
- the design data is data including design information of the pattern formed on the wafer, and specifically, the coordinates of the vertex of the pattern, the position, shape, and size of the pattern, the number of the layer to which the pattern belongs, and the like of the pattern. Contains design information.
- the CAD pattern on the design data is a virtual pattern defined by the design information of the pattern included in the design data.
- This step 1-1 is a step of identifying a CAD pattern from a plurality of CAD patterns included in the design data. In this step 1-1, a plurality of CAD patterns may be designated.
- the arithmetic system 150 converts the designated CAD pattern into a CAD image. More specifically, the arithmetic system 150 draws the CAD pattern 100 as shown in FIG. 3 based on the CAD pattern design information (for example, the coordinates of the vertices of the CAD pattern) included in the design data, and draws a certain area. A CAD image 101 having the is generated. The arithmetic system 150 stores the generated CAD image 101 in the storage device 162 of the arithmetic system 150.
- step 1-3 the scanning electron microscope 50 as an image generation device generates an SEM image of the pattern on the wafer actually formed based on the CAD pattern specified in step 1-1.
- FIG. 4 is a schematic diagram showing an example of an SEM image generated by the scanning electron microscope 50.
- reference numeral 104 represents an SEM image
- reference numeral 105 represents a pattern appearing on the SEM image 104.
- the pattern 105 corresponds to the specified CAD pattern, that is, the CAD pattern 100 on the CAD image 101.
- the computing system 150 acquires the SEM image 104 from the scanning electron microscope 50 and stores the SEM image 104 in the storage device 162.
- step 1-4 the arithmetic system 150 creates training data including the CAD image generated in step 1-2 and the SEM image generated in step 1-3.
- step 1-5 the arithmetic system 150 determines model parameters (weighting factors and the like) by machine learning using the training data including the CAD image and the SEM image.
- the CAD image included in the training data is used as an explanatory variable
- the SEM image included in the training data is used as an objective variable.
- the computing system 150 and the scanning electron microscope 50 repeat the above-mentioned steps 1-1 to 1-5 a preset number of times to build a model by machine learning. That is, the model is constructed by machine learning using a plurality of CAD images converted from a plurality of CAD patterns on the design data and training data including a plurality of SEM images corresponding to these CAD images. The model thus constructed by machine learning is also referred to as a trained model.
- the computing system 150 stores the model in the storage device 162. The same design data may be used, or a plurality of design data may be used, while steps 1-1 to 1-5 are repeated.
- FIG. 5 is a schematic diagram showing an example of a model used for machine learning.
- the model is a neural network having an input layer 201, a plurality of intermediate layers (also referred to as hidden layers) 202, and an output layer 203.
- a CAD image is input to the input layer 201 of the model. More specifically, the numerical value of each pixel forming the CAD image is input to the input layer 201. In one example, when the CAD image is a grayscale image, the numerical value indicating the gray level of each pixel is input to each node (neuron) of the input layer 201 of the model.
- the output layer 203 outputs the numerical value of the pixel corresponding to the pixel which comprises the CAD image input into the input layer 201, respectively.
- Deep learning is suitable as the machine learning algorithm. Deep learning is a learning method based on a neural network having intermediate layers. In this specification, machine learning using a neural network including an input layer, a plurality of intermediate layers (hidden layers), and an output layer is called deep learning. Models built using deep learning can accurately predict the shape of patterns that can deform due to various factors.
- FIG. 6 shows an embodiment of a method of aligning a CAD pattern and a pattern on an SEM image (that is, image matching processing) using the model composed of a neural network constructed by machine learning. This will be described with reference to the flowchart.
- step 2-1 the arithmetic system 150 specifies the CAD pattern on the design data.
- step 2-2 the scanning electron microscope 50 generates an SEM image (actual image) of the pattern actually formed on the wafer based on the design data used in step 2-1.
- the computing system 150 acquires the SEM image from the scanning electron microscope 50 and stores the SEM image in the storage device 162.
- step 2-3 the arithmetic system 150 converts the CAD pattern specified in step 2-1 into a CAD image.
- the computing system 150 stores the CAD image in the storage device 162.
- step 2-4 the arithmetic system 150 inputs the CAD image obtained in step 2-3 into the model.
- step 2-5 the arithmetic system 150 outputs a pseudo image from the model by executing calculation according to the algorithm defined by the model.
- step 2-6 the arithmetic system 150 determines a pattern having a shape closest to the shape of the CAD pattern on the pseudo image from the plurality of patterns on the SEM image generated in step 2-2.
- a known technique such as a phase-only correlation method can be used to determine the similarity between the pattern on the SEM image and the CAD pattern on the pseudo image.
- FIG. 7 is a schematic diagram showing an example of a CAD image, an SEM image, and a pseudo image. Since the CAD pattern 302 on the CAD image 301 is created based on the coordinates of each vertex of the CAD pattern included in the design data, the CAD pattern 302 is composed of straight line segments. On the other hand, the actual pattern 312 on the SEM image 311 is deformed compared to the CAD pattern 302 due to the manufacturing process and/or the imaging process. The CAD pattern 322 on the pseudo image 321 output from the model has a shape close to the actual pattern 312 on the SEM image 311.
- the model constructed by machine learning such as deep learning can accurately predict the actual pattern from the CAD pattern on the design data. That is, the CAD pattern that appears on the pseudo image output from the model is expected to have a shape close to the actual pattern. Therefore, the arithmetic system 150 can correctly align the CAD pattern on the pseudo image with the pattern on the image generated by the image generation device (that is, image matching processing).
- the arithmetic system 150 and the scanning electron microscope 50 execute the above steps 2-1 to 2-6 in accordance with the instruction contained in the program stored in the storage device 162.
- the program is first recorded on a computer-readable recording medium that is a non-transitory tangible material, and then provided to the computing system 150 via the recording medium.
- the program may be provided to computing system 150 via a communication network such as the Internet or a local area network.
- the arithmetic system 150 uses the pattern matching result of the CAD pattern on the pseudo image and the pattern on the SEM image. May be used to adjust model parameters (weighting factors, etc.).
- model parameters weighting factors, etc.
- the arithmetic system 150 inputs the CAD image 301 converted from the CAD pattern on the design data into the model. Next, the arithmetic system 150 performs pattern matching between the CAD pattern 322 on the pseudo image 321 output from the model and the pattern 312 on the SEM image (actual image) 311 included in the training data used to construct the model. To execute.
- the SEM image 311 used for this pattern matching corresponds to the CAD image 301 input to the model.
- the pattern matching is executed according to a known algorithm for determining whether or not the CAD pattern 322 on the pseudo image 321 matches the pattern 312 on the SEM image 311.
- the arithmetic system 150 outputs the result of pattern matching. That is, if the CAD pattern 322 on the pseudo image 321 output from the model matches the pattern 312 on the SEM image 311 within a predetermined allowable range, the arithmetic system 150 indicates that the pattern matching has succeeded. A numerical value (for example, 1) is output. On the other hand, if the CAD pattern 322 on the pseudo image 321 output from the model does not match the pattern 312 on the SEM image 311 within a predetermined allowable range, the arithmetic system 150 indicates that the pattern matching has failed. Is output (for example, 0).
- the arithmetic system 150 executes machine learning, adjusts the parameters of the model, and executes the pattern matching so that the first numerical value is output as the result of the pattern matching. That is, the arithmetic system 150 executes machine learning and executes model learning so that the CAD pattern 322 on the pseudo image 321 output from the model matches the pattern 312 on the SEM image 311 within a predetermined allowable range. Adjust. By such an operation, the model can output the pseudo image 321 having a tendency more suitable for matching.
- FIG. 9 is a flowchart illustrating another embodiment for constructing a model composed of a neural network by machine learning. Steps 3-1 to 3-3 of this embodiment are the same as steps 1-1 to 1-3 shown in FIG. 2, and thus their duplicate description will be omitted.
- the training data used for constructing the model further includes training additional information data in order to bring the shape of the CAD pattern on the pseudo image closer to the shape of the actual pattern on the wafer.
- step 3-4 the arithmetic system 150 causes the position information of the CAD pattern specified in step 3-1, the peripheral image converted from the CAD pattern around the CAD pattern specified in step 3-1, Training additional information data including at least one of the layer images converted from the CAD pattern existing above or below the CAD pattern designated in step 3-1 is created.
- the layer image may be a layer image converted from the CAD pattern existing above and below the specified CAD pattern.
- the CAD pattern position information is included in the design data. Therefore, the arithmetic system 150 can obtain the position information of the designated CAD pattern from the design data.
- the peripheral image is generated by the arithmetic system 150. More specifically, the arithmetic system 150 draws these CAD patterns based on the design information of the CAD patterns existing around the specified CAD pattern, and generates a peripheral image having a certain area.
- FIG. 10 is a schematic diagram showing an example of a peripheral image.
- reference numeral 401 represents the CAD pattern specified in step 3-1
- reference numeral 403 represents the CAD image generated in step 3-2
- reference numeral 405 exists around the CAD image 403. It represents a CAD pattern
- reference numeral 406 represents a peripheral image converted from the CAD pattern 405.
- Layer images are also generated by the computing system 150. More specifically, the arithmetic system 150 draws these CAD patterns based on the design information of the CAD patterns existing above and/or below the specified CAD pattern to generate a layer image having a certain area. To do.
- FIG. 11 is a schematic diagram showing an example of a layer image converted from a CAD pattern existing above and below a designated CAD pattern.
- reference numeral 501 represents the CAD pattern designated in step 3-1
- reference numeral 503 represents the CAD image generated in step 3-2
- reference numerals 505 and 506 represent the designated CAD pattern.
- the CAD patterns existing in the upper and lower layers that overlap each other are represented, and reference numerals 508 and 509 represent layer images converted from the CAD patterns 505 and 506 of the upper and lower layers.
- step 3-5 the computing system 150 is created in the CAD image generated in step 3-2, the SEM image generated in step 3-3, and the step 3-4.
- Training data including the additional information data for training is created.
- step 3-6 the arithmetic system 150 uses the above training data to determine the parameters (weighting coefficient etc.) of the model composed of the neural network by machine learning.
- the structure of the model used in this embodiment is basically the same as the model shown in FIG. 5, but the input layer of the model further includes a node (neuron) to which the additional information data for training is input. They differ in points.
- the computing system 150 and the scanning electron microscope 50 repeat the above steps 3-1 to 3-6 a preset number of times to build a model by machine learning. That is, the model is machine-learned using a plurality of CAD images converted from a plurality of CAD patterns on the design data, a plurality of SEM images corresponding to these CAD images, and training data including training additional information data. Be built.
- the training additional information data includes position information of a plurality of CAD patterns obtained by repeating step 3-1; a plurality of peripheral images converted from a plurality of CAD patterns around the plurality of CAD patterns; At least one of the plurality of layer images converted from the plurality of CAD patterns existing above or below the plurality of CAD patterns is included.
- the plurality of layer images may be a plurality of layer images converted from CAD patterns existing above and below the plurality of CAD patterns.
- FIG. 12 is a flow chart showing an embodiment of a method of aligning the CAD pattern with the pattern on the SEM image (that is, image matching processing) using the model created according to the flow chart shown in FIG.
- step 4-1 the arithmetic system 150 specifies the CAD pattern on the design data.
- the scanning electron microscope 50 generates an SEM image (actual image) of the pattern actually formed on the wafer based on the design data used in step 4-1.
- the computing system 150 acquires the SEM image from the scanning electron microscope 50 and stores the SEM image in the storage device 162.
- the arithmetic system 150 converts the CAD pattern specified in step 4-1 into a CAD image.
- the computing system 150 stores the CAD image in the storage device 162.
- step 4-4 the arithmetic system 150 creates additional information data related to the CAD pattern specified in step 4-1.
- This additional information data includes the position information of the CAD pattern designated in step 4-1, the peripheral image converted from the CAD pattern around the designated CAD pattern, and the top or bottom of the designated CAD pattern.
- the layer image may be a layer image converted from the CAD pattern existing above and below the specified CAD pattern.
- the CAD pattern position information is included in the design data. Therefore, the arithmetic system 150 can obtain the position information of the designated CAD pattern from the design data.
- the peripheral image is generated by the arithmetic system 150. More specifically, the arithmetic system 150 draws these CAD patterns based on the design information of the CAD patterns existing around the specified CAD pattern (for example, the coordinates of the vertices of the CAD pattern), and draws a certain area. Generate the surrounding image you have.
- the layer image is also generated by the arithmetic system 150.
- the arithmetic system 150 draws these CAD patterns based on the design information of the CAD patterns existing above and/or below the specified CAD patterns (for example, the coordinates of the vertices of the CAD patterns). , Generate a layer image with a certain area.
- FIGS. 10 and 11 are also applicable to the peripheral image and the layer image included in the additional information data, and thus the illustration thereof is omitted.
- step 4-5 the arithmetic system 150 inputs the CAD image obtained in step 4-3 and the additional information data created in step 4-4 into the model.
- step 4-6 the arithmetic system 150 outputs a pseudo image from the model by executing calculation according to the algorithm defined by the model.
- step 4-7 the arithmetic system 150 determines a pattern having a shape closest to the shape of the CAD pattern on the pseudo image from the plurality of patterns on the SEM image generated in step 4-2.
- the pattern deformation tendency appearing on the SEM image may change depending on factors such as the position of the pattern, other patterns existing around the pattern, and other patterns existing above and/or below the pattern. That is, these factors can influence the shape of the pattern on the SEM image.
- the model since the model is constructed using the training additional information data and the additional information data is input to the model, the model can predict a pattern having a shape closer to the CAD pattern. Therefore, the arithmetic system 150 can more correctly align the CAD pattern on the pseudo image with the pattern on the image generated by the scanning electron microscope 50 (that is, the image matching process).
- the present invention relates to an image matching process for aligning a pattern on design data with a pattern on an image, and is particularly applicable to an image matching process using a model constructed by machine learning.
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Abstract
Description
一態様では、前記訓練データは、訓練用付加情報データをさらに含み、前記訓練用付加情報データは、前記複数のCADパターンの位置情報、前記複数のCADパターンの周辺にある複数のCADパターンから変換された複数の周辺画像、および前記複数のCADパターンの上または下に存在する複数のCADパターンから変換された複数のレイヤー画像のうちの少なくとも1つを含む。
一態様では、前記CAD画像に加えて、付加情報データを前記モデルに入力し、前記付加情報データは、前記指定されたCADパターンの位置情報、前記指定されたCADパターンの周辺にあるCADパターンから変換された周辺画像、および前記指定されたCADパターンの上または下に存在するCADパターンから変換されたレイヤー画像のうちの少なくとも1つを含む。
一態様では、前記方法は、前記モデルから出力された疑似画像上のCADパターンが、前記画像生成装置によって生成された画像上の対応するパターンに所定の許容範囲内で合致するように、機械学習を実行して前記モデルのパラメータを調整する工程をさらに含む。
一態様では、前記訓練データは、訓練用付加情報データをさらに含み、前記訓練用付加情報データは、前記複数のCADパターンの位置情報、前記複数のCADパターンの周辺にある複数のCADパターンから変換された複数の周辺画像、および前記複数のCADパターンの上または下に存在する複数のCADパターンから変換された複数のレイヤー画像のうちの少なくとも1つを含む。
一態様では、前記CAD画像に加えて、付加情報データを前記モデルに入力し、前記付加情報データは、前記指定されたCADパターンの位置情報、前記指定されたCADパターンの周辺にあるCADパターンから変換された周辺画像、および前記指定されたCADパターンの上または下に存在するCADパターンから変換されたレイヤー画像のうちの少なくとも1つを含む。
一態様では、前記演算システムは、前記モデルから出力された疑似画像上のCADパターンが、前記画像生成装置によって生成された画像上の対応するパターンに所定の許容範囲内で合致するように、機械学習を実行して前記モデルのパラメータを調整するように動作する。
図1は、撮像装置の一実施形態を示す模式図である。図1に示すように、撮像装置は、走査電子顕微鏡50および演算システム150を備えている。走査電子顕微鏡50は、画像生成装置の一例である。走査電子顕微鏡50は、演算システム150に接続されており、走査電子顕微鏡50の動作は演算システム150によって制御される。
ステップ1-1では、演算システム150は、設計データ上のCADパターンを指定する。設計データは、ウェーハに形成されたパターンの設計情報を含むデータであり、具体的には、パターンの頂点の座標、パターンの位置、形状、および大きさ、パターンが属する層の番号などのパターンの設計情報を含む。設計データ上のCADパターンは、設計データに含まれるパターンの設計情報によって定義される仮想パターンである。このステップ1-1は、設計データに含まれる複数のCADパターンから、あるCADパターンを特定する工程である。このステップ1-1では、複数のCADパターンが指定されてもよい。
ステップ1-5では、演算システム150は、CAD画像とSEM画像とを含む訓練データを用いて、モデルのパラメータ(重み係数など)を機械学習により決定する。機械学習では、訓練データに含まれるCAD画像は説明変数として用いられ、訓練データに含まれるSEM画像は目的変数として用いられる。
ステップ2-2では、走査電子顕微鏡50は、ステップ2-1で使用された設計データに基づいて実際に形成されたウェーハ上のパターンのSEM画像(実画像)を生成する。演算システム150は、SEM画像を走査電子顕微鏡50から取得し、SEM画像を記憶装置162内に記憶する。
ステップ2-3では、演算システム150は、ステップ2-1で指定されたCADパターンをCAD画像に変換する。演算システム150は、CAD画像を記憶装置162内に記憶する。
ステップ2-4では、演算システム150は、ステップ2-3で得られたCAD画像を上記モデルに入力する。
ステップ2-5では、演算システム150は、モデルによって定義されたアルゴリズムに従って計算を実行することで、モデルから疑似画像を出力させる。
ステップ2-6では、演算システム150は、ステップ2-2で生成されたSEM画像上の複数のパターンの中から、疑似画像上のCADパターンの形状に最も近い形状を有するパターンを決定する。SEM画像上のパターンと、疑似画像上のCADパターンとの間の類似性の判断には、位相限定相関法などの公知の技術を使用することができる。
本実施形態では、疑似画像上のCADパターンの形状を、ウェーハ上の実際のパターンの形状により近づけるために、モデルの構築に使用される訓練データは、訓練用付加情報データをさらに含んでいる。
ステップ3-6では、演算システム150は、上記訓練データを用いて、ニューラルネットワークからなるモデルのパラメータ(重み係数など)を機械学習により決定する。本実施形態に使用されるモデルの構造は、図5に示すモデルと基本的に同じであるが、モデルの入力層は、訓練用付加情報データが入力されるノード(ニューロン)をさらに備えている点で異なっている。
ステップ4-2では、走査電子顕微鏡50は、ステップ4-1で使用された設計データに基づいて実際に形成されたウェーハ上のパターンのSEM画像(実画像)を生成する。演算システム150は、SEM画像を走査電子顕微鏡50から取得し、SEM画像を記憶装置162内に記憶する。
ステップ4-3では、演算システム150は、ステップ4-1で指定されたCADパターンをCAD画像に変換する。演算システム150は、CAD画像を記憶装置162内に記憶する。
ステップ4-6では、演算システム150は、モデルによって定義されたアルゴリズムに従って計算を実行することで、モデルから疑似画像を出力させる。
ステップ4-7では、演算システム150は、ステップ4-2で生成されたSEM画像上の複数のパターンの中から、疑似画像上のCADパターンの形状に最も近い形状を有するパターンを決定する。
111 電子銃
112 集束レンズ
113 X偏向器
114 Y偏向器
115 対物レンズ
116 レンズ制御装置
117 偏向制御装置
118 画像取得装置
120 試料チャンバー
121 試料ステージ
122 ステージ制御装置
124 ウェーハ
130 二次電子検出器
131 反射電子検出器
140 ウェーハ搬送装置
150 演算システム
161 データベース
162 記憶装置
163 処理装置
Claims (10)
- 設計データ上の指定されたCADパターンをCAD画像に変換し、
前記CAD画像を、機械学習により構築されたモデルに入力し、
前記モデルによって定義されたアルゴリズムに従って計算を実行することで、前記モデルから疑似画像を出力し、
画像生成装置によって生成された画像上の複数のパターンの中から、前記疑似画像上のCADパターンの形状に最も近い形状を有するパターンを決定する方法。 - 前記モデルは、設計データ上の複数のCADパターンから変換された複数のCAD画像と、前記複数のCAD画像に対応する、画像生成装置によって生成された複数の画像を少なくとも含む訓練データを用いて機械学習により構築されたモデルである、請求項1に記載の方法。
- 前記訓練データは、訓練用付加情報データをさらに含み、
前記訓練用付加情報データは、前記複数のCADパターンの位置情報、前記複数のCADパターンの周辺にある複数のCADパターンから変換された複数の周辺画像、および前記複数のCADパターンの上または下に存在する複数のCADパターンから変換された複数のレイヤー画像のうちの少なくとも1つを含む、請求項2に記載の方法。 - 前記CAD画像に加えて、付加情報データを前記モデルに入力し、
前記付加情報データは、前記指定されたCADパターンの位置情報、前記指定されたCADパターンの周辺にあるCADパターンから変換された周辺画像、および前記指定されたCADパターンの上または下に存在するCADパターンから変換されたレイヤー画像のうちの少なくとも1つを含む、請求項3に記載の方法。 - 前記モデルから出力された疑似画像上のCADパターンが、前記画像生成装置によって生成された画像上の対応するパターンに所定の許容範囲内で合致するように、機械学習を実行して前記モデルのパラメータを調整する工程をさらに含む、請求項1乃至4のいずれか一項に記載の方法。
- 画像マッチング処理を実行するための演算システムであって、
機械学習により構築されたモデル、およびプログラムが格納された記憶装置と、
前記プログラムに従って演算を実行する処理装置を備え、
前記演算システムは、
設計データ上の指定されたCADパターンをCAD画像に変換し、
前記CAD画像を前記モデルに入力し、
前記モデルによって定義されたアルゴリズムに従って計算を実行することで、前記モデルから疑似画像を出力させ、
画像生成装置によって生成された画像上の複数のパターンの中から、前記疑似画像上のCADパターンの形状に最も近い形状を有するパターンを決定するように動作する、演算システム。 - 前記モデルは、設計データ上の複数のCADパターンから変換された複数のCAD画像と、前記複数のCAD画像に対応する、画像生成装置によって生成された複数の画像を少なくとも含む訓練データを用いて機械学習により構築されたモデルである、請求項6に記載の演算システム。
- 前記訓練データは、訓練用付加情報データをさらに含み、
前記訓練用付加情報データは、前記複数のCADパターンの位置情報、前記複数のCADパターンの周辺にある複数のCADパターンから変換された複数の周辺画像、および前記複数のCADパターンの上または下に存在する複数のCADパターンから変換された複数のレイヤー画像のうちの少なくとも1つを含む、請求項7に記載の演算システム。 - 前記演算システムは、前記CAD画像に加えて、付加情報データを前記モデルに入力するように動作し、
前記付加情報データは、前記指定されたCADパターンの位置情報、前記指定されたCADパターンの周辺にあるCADパターンから変換された周辺画像、および前記指定されたCADパターンの上または下に存在するCADパターンから変換されたレイヤー画像のうちの少なくとも1つを含む、請求項8に記載の演算システム。 - 前記演算システムは、前記モデルから出力された疑似画像上のCADパターンが、前記画像生成装置によって生成された画像上の対応するパターンに所定の許容範囲内で合致するように、機械学習を実行して前記モデルのパラメータを調整するように動作する、請求項6乃至9のいずれか一項に記載の演算システム。
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