JP2015007871A - Template creation device and method, and charged particle beam device using template creation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically create a template which correctly matches an SADP pattern.SOLUTION: The present invention determines whether design data includes a closed figure, and when the design data includes a closed figure, cuts out a pattern of a feature position from the design data, and simulates the cut-out pattern to generate a template.

Description

  The present invention relates to a template creation apparatus and method for automatically generating a template using only circuit pattern design data, and a charged particle beam apparatus having the function.

  A technique for searching a given specific shape (template) from a target image (FOV: Field Of View) is called template matching. Template matching has been widely used conventionally. For example, in semiconductor wafer pattern measurement using a scanning electron microscope (SEM), template matching is performed when obtaining a measurement position. Rough alignment of measurement positions is performed by moving a stage on which a semiconductor wafer is placed. However, only by positioning by moving the stage, it is inevitable that a large shift occurs on an image taken at a high magnification as in an electron microscope. Template matching is performed to correct this deviation and perform measurement at an accurate position.

  Further, with the recent miniaturization of patterns, SADP method (Self-Aligned Double Patterning) is used in the lithography process. When the state of a pattern formed by the SADP method (hereinafter referred to as “SADP pattern”) is observed with a scanning electron microscope, an addressing point (hereinafter referred to as “AP”) is designated as a template. In some cases, only circuit patterns can be selected.

Japanese Patent No. 4215454

  Conventionally, there is a method disclosed in Patent Document 1 as a matching technique for an uneven pattern. The method of Patent Document 1 performs pattern matching without particularly distinguishing between a U-shape and other shapes. However, in this method, since a straight line portion is more easily extracted as a feature amount than a U-shaped curved portion, the U-shape may not be correctly retrieved from the target image. For example, when a plurality of U-shapes are arranged in parallel, they may be matched with two linear patterns of two adjacent U-shapes. For this reason, manual position adjustment is still required for the SADP method pattern.

  In order to solve the above problems, for example, the configuration described in the claims is adopted. Although the present specification includes a plurality of means for solving the above-described problem, the template creation apparatus as an example thereof performs a first calculation for determining whether or not a closed figure (for example, a U-shape) is included in the design data. And a second calculation unit that generates a template by simulating the extracted pattern after cutting out the pattern of the feature position from the design data when the design data includes a closed figure.

  According to the present invention, it is possible to automatically create a template that includes a U-shaped portion and accurately matches the SADP pattern. Problems, configurations, and effects other than those described above will become apparent from the following description of embodiments.

Schematic of the scanning electron microscope which concerns on an Example. 6 is a flowchart showing an overview of template creation processing. Image of U-shaped recognition when Design template is Clear. Image of U-shaped recognition when Design template is Dark. The figure which shows the cutout image of a feature position. The figure which shows a simulation image. The figure which shows the adjustment image of a template width.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiment of the present invention is not limited to the embodiments described later, and various modifications can be made within the scope of the technical idea.

  FIG. 1 shows a schematic configuration of a scanning electron microscope which is an embodiment of the present invention. The scanning electron microscope according to the embodiment includes a mirror unit 101, an electron gun 102, a deflector 104, an electron detector 106, an amplifier 107, an image processor 109, a control computer 110, a display device 111, and an input device 112. . An electron beam 103 emitted from the electron gun 102 is converged by an electron lens (not shown) and irradiated onto the sample 105. The intensity of a signal (for example, secondary electrons or reflected electrons) generated from the surface of the sample 105 by the irradiation of the electron beam 103 is detected by the electron detector 106 and amplified by the amplifier 107. The deflector 104 raster scans an electron beam on the sample surface by a control signal 108 of a control computer 110 (hereinafter also referred to as “control processor” or “control system”). The image processor 109 performs AD (Analog to Digital) conversion on the signal output from the amplifier 107 to generate digital image data. Further, the image processor 109 creates a profile from the digital image data by projection processing. Hereinafter, the digital signal waveform is also called a profile. The display device 111 displays image data (image data) captured using the electron beam 103. An image processor 109 is an image memory that stores digital image data and a device that executes various types of image processing, and includes a display control circuit that performs display control. Input means 112 such as a keyboard and a mouse is connected to the control computer 110.

  In this embodiment, the scanning electron microscope is described as an example, but the present invention can also be applied to other charged particle beam apparatuses such as a focused ion beam apparatus. The control computer 110 is also used as a template creation device described later. In the description of FIG. 1, the control computer 110 is integrated with the scanning electron microscope, but a template creation process as described below may be performed by a control processor provided separately from the scanning electron microscope. Alternatively, a program for performing template creation processing described below may be registered in a storage medium, and the program may be executed by the control computer 110. The design data necessary for creating the template is stored in a storage medium (not shown).

  FIG. 2 shows a flow of template creation processing by the control computer 110. In step S201, the control computer 110 determines whether the template is Clear (convex pattern) or Dark (concave pattern) based on the design data. In the next step S202, the control computer 110 checks whether or not a U-shape exists in the design data. The presence or absence of the U-shape is checked by the following method.

  When the design data is Clear: 1 If the angle of six 90 ° angles and two two 270 ° angles appear continuously in a closed figure, it is determined to be U-shaped. FIG. 3 shows an image of U-shaped recognition when the Design template is Clear.

  When the design data is Dark: 1 If the angle in the closed figure is 6 270 ° angles and 2 90 ° angles appear in succession, it is determined to be U-shaped. FIG. 4 shows an image of U-shaped recognition when the Design template is Dark.

  When the U-shape exists, the control computer 110 cuts out the feature position (step S203). FIG. 5 shows a cutout image of the feature position. In FIG. 5, the feature position to be cut out is shown surrounded by a dotted line. In extracting the feature position, an ROI (region of interest) is set with a specified size so that the bottom of the first U-shape is the center in the Y direction.

  In the next step S204, the control computer 110 performs a simulation in order to make the shape of the extracted feature position close to a U-shape. In other words, a simulation is executed as a Design template in order to approximate the shape of the feature position in the target image (FOV). FIG. 6 shows an image of the simulation result. As shown in FIG. 6, the rectangular pattern is transformed into a rounded pattern by executing the simulation.

  In the next step 205, it is checked whether a pattern other than the U-shape exists in the vicinity of the ROI. When a pattern other than the U-shape exists in the vicinity of the ROI, the control computer 110 adjusts the template width to be expanded in the Y direction (step S206). FIG. 7 shows an extended image of the template width. FIG. 7 is an example in which the template width of FIG. 6 is expanded in the Y direction when a linear pattern exists in the vicinity of the U-shape. In this way, the matching accuracy can be further improved by extending the template width in the direction of the U-shaped tip and executing matching in combination with other patterns. If there is no pattern other than the U-shape in the vicinity of the ROI, the control computer 110 creates a template using only the U-shape extracted first (step S208).

  Incidentally, when a negative result is obtained in step S202 (when the U-shape does not exist in the FOV), in step S207, the control computer 110 creates a template for the entire FOV.

  As described above, when the scanning electron microscope according to the present embodiment is used, a template including a U-shaped portion and accurately matching the SADP pattern can be automatically created. That is, a template including a U-shape close to an actual pattern can be generated by cutting out a pattern including a U-shaped portion from design data and then simulating the pattern. Therefore, even when the matching target is an SADP pattern, high matching accuracy can be realized. In addition, when other characteristic patterns exist in the vicinity of the U-shaped portion as the ROI, a template that combines the above-mentioned U-shaped and other characteristic patterns can be used for matching. Accuracy can be achieved.

  In addition, this invention is not limited to the Example mentioned above, Various modifications are included. For example, in the above-described embodiments, in order to explain the present invention in an easy-to-understand manner, some embodiments are described in detail, and it is not always necessary to include all the configurations described. Further, a part of a certain embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of a certain embodiment. Moreover, it is also possible to add, delete, or replace another configuration for a part of the configuration of each embodiment.

  Moreover, you may implement | achieve some or all of each structure, a function, a process part, a process means, etc. which were mentioned above as an integrated circuit or other hardware, for example. Each of the above-described configurations, functions, and the like may be realized by the processor interpreting and executing a program that realizes each function. That is, it may be realized as software. Information such as programs, tables, and files for realizing each function can be stored in a memory, a hard disk, a storage device such as an SSD (Solid State Drive), or a storage medium such as an IC card, an SD card, or a DVD.

  Control lines and information lines indicate what is considered necessary for the description, and do not represent all control lines and information lines necessary for the product. In practice, it can be considered that almost all components are connected to each other.

  DESCRIPTION OF SYMBOLS 101 ... Mirror part, 102 ... Electron gun, 103 ... Electron beam, 104 ... Deflector, 105 ... Sample, 106 ... Electron detector, 107 ... Amplifier, 108 ... Control signal, 109 ... Image processor, 110 ... For control Computer, 111 ... display device, 112 ... input device.

Claims (6)

A first calculation unit for determining whether or not the design data includes a closed graphic;
And a second calculation unit that generates a template by simulating the extracted pattern after cutting out the pattern of the feature position from the design data when the design data includes a closed figure. The template creation device according to claim 1,
The second calculation unit determines whether another pattern other than a closed figure exists near the tip of the pattern after the simulation. If another pattern exists, the second calculation unit includes the another pattern. As described above, the template creation apparatus is characterized in that the size of the template is expanded in the direction of the end of the closed figure. A first process in which the computer determines whether the design data includes a closed graphic;
And a second process of generating a template by simulating the extracted pattern after cutting out the pattern of the feature position from the design data when the design data includes a closed figure. The template creation method according to claim 3,
The computer determines whether there is another pattern other than a closed figure near the tip of the simulated pattern. If another pattern exists, the computer includes A template creation method characterized by expanding the size in the direction of the tip of a closed figure. A charged particle beam source for emitting charged particles;
A detector for detecting a signal generated from an irradiation position of the charged particles;
A first calculation unit for determining whether or not the design data includes a closed graphic;
When the design data includes a closed figure, after cutting out the pattern of the feature position from the design data, a second calculation unit that simulates the cut pattern and generates a template;
A charged particle beam apparatus comprising: a third calculation unit that detects a pattern that matches the generated template from an image detected by the detector. In the charged particle beam device according to claim 5,
The second calculation unit determines whether another pattern other than a closed figure exists near the tip of the pattern after the simulation. If another pattern exists, the second calculation unit includes the another pattern. Thus, the size of the template is expanded in the direction of the tip of the closed figure.

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