JP2007103645A - Pattern inspection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize automated generation of a recipe to be executed subsequently by obtaining and storing deviation between CAD (Computer Aided Design) data and a pattern inspection apparatus at the time of executing the recipe. <P>SOLUTION: A plurality of patterns having priorities are registered to the recipe as the matching patterns of a global alignment point at the time of generating the recipe from the CAD data. When the generated recipe is executed first with the pattern inspection apparatus, pattern matching is conducted using the matching patterns in the priority sequence after movement to the global alignment point (801 to 803). When the pattern matching is completed successfully; the global alignment is conducted in order to obtain amount of deviation and amount of rotation, by utilizing coordinates of the position at which the pattern is found and the coordinates designated from the CAD data. If pattern matching has failed in all the matching patterns prepared; the global alignment is conducted by temporarily suspending the recipe, designating by an operator the pattern which should be located at the coordinates stored in the recipe on the image picked up (804 to 806), and utilizing the coordinate of the designated location and the coordinate designated from the CAD data. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pattern inspection apparatus that inspects a pattern in a semiconductor chip formed on a semiconductor wafer according to a recipe created based on CAD data, and relates to a method for automating global alignment at the time of executing a recipe.

Conventionally, in order to correct the coordinate deviation between the CAD data and the pattern inspection device, the semiconductor wafer to be measured must be observed with the pattern inspection device before or at the time of recipe creation, and the amount of deviation must be measured in advance. I had to.
Japanese Patent Laid-Open No. 5-47901

  FIG. 1 shows the relationship between the coordinates on the CAD data and the coordinates on the pattern inspection apparatus. In CAD data, ideal coordinates 101 are formed, whereas in a pattern inspection apparatus, a wafer, which is a sample to be measured, is not accurately placed on a sample table. The observed pattern on the wafer is usually accompanied by an offset 103 in the XY direction and a rotation 104. In the pattern inspection apparatus, this offset and rotation can be corrected by performing global alignment. Global alignment refers to the ideal coordinates from the ideal coordinates to the actual coordinates and the actual coordinates using the ideal coordinates of an arbitrary pattern (global alignment point) on the sample and the actual coordinates where the pattern exists on the pattern inspection apparatus. This is a technique for obtaining coefficients such as offset and rotation for obtaining ideal coordinates from coordinates.

  In the pattern inspection apparatus, data called a recipe is created in order to automatically perform an inspection job. As shown in FIG. 2, the recipe includes job execution conditions and sequences as parameters, and a pattern used for global alignment and its ideal coordinates are a part thereof. When a recipe is created from CAD data, ideal coordinates calculated from the CAD data are registered in the recipe as global alignment points and coordinates of the inspection target pattern. When this recipe is executed, there is no look-ahead information for offset and rotation, so even if it moves to the coordinates of the global alignment point, the expected pattern cannot be found in the field of view of the move destination. As a result, even if the detection of the pattern of the global alignment point is automated by pattern matching in order to automate the recipe, the pattern matching fails, making it difficult to automate the recipe.

  An object of the present invention is to automate subsequent recipes by obtaining a deviation amount between CAD data and a pattern inspection apparatus when a recipe is executed and storing it.

  In order to achieve the above object, in the present invention, when creating a recipe from CAD data, a plurality of prioritized patterns are registered in the recipe as matching patterns for global alignment points. When the created recipe is first executed by the pattern inspection apparatus, after moving to the global alignment point, pattern matching is performed using the matching patterns in order of priority. At this time, if the pattern matching is successful, global alignment is performed using the coordinates of the position where the pattern is found and the coordinates specified from the CAD data, and the shift amount and the rotation amount are obtained.

  If pattern matching fails for all of the prepared matching patterns, the recipe is temporarily stopped, and the operator should specify the pattern that should be in the coordinates stored in the recipe on the image captured by the pattern inspection device, By performing global alignment using the coordinates of the specified position and the coordinates specified from the CAD data, the shift amount and the rotation amount can be calculated.

  Also, memorize the amount of deviation and rotation obtained, and automate the recipe by using the amount of deviation and rotation when the recipe is executed next time or when a new recipe is created from CAD data. To do.

  According to the present invention, global alignment by recipe execution can be automated.

  Embodiments of the present invention will be described below with reference to the drawings. In the present invention, in the process of executing the recipe created from the CAD data, the shift amount and the rotation amount of the coordinates of the CAD data and the pattern inspection apparatus are obtained and stored, so that the subsequent recipe is automated and newly created. Realized recipe automation.

  FIG. 3 shows an example of a plurality of patterns selected for pattern matching of global alignment points.

  When creating a recipe from CAD data, a plurality of patterns are selected as patterns for global alignment points, and each of them is selected as a matching pattern candidate 1 (301), a matching pattern candidate 2 (302), and a matching pattern candidate. 3 (303) is assigned a priority, and pattern matching information and the coordinates of the pattern obtained from the CAD data are registered in the recipe. Here, three patterns are selected in the example, but the number of matching pattern candidates to be selected may be three or more and less than three.

  At this time, image data is created from CAD data of each matching pattern candidate, and this is also registered in the recipe. FIG. 4 is an example of the created image data. A mark 404 indicating the position indicated by the coordinates of the registered pattern is added to each of the images 401, 402, and 403 together with information for pattern matching.

  FIG. 5 is an example of a processing flow when performing inspection using a recipe in the pattern inspection apparatus. First, in step 501, the wafer to be measured is brought into an observable position, and then in step 502, the global alignment is performed to correct the coordinates, and then in step 503, the coordinates are registered in the recipe. Perform pattern inspection. When inspection of all patterns is completed, the process proceeds to step 504, where the inspection result is stored, and in step 505, the wafer is carried out to the original position and the recipe is terminated.

  FIG. 6 is a processing flow at the time of global alignment. First, in step 601, the coordinates of the global alignment point registered in the recipe are moved. Thereafter, after the field of view of the movement destination is imaged in step 602, pattern matching is performed using the image captured in step 603 and pattern matching information created from CAD data. If the pattern matching is successful, the coordinates of the position detected in step 604 are acquired. After repeating this for the number of global alignment points through the determination in step 605, the combination of the global alignment point pattern coordinates obtained from the CAD data in step 606 and the coordinates at which the pattern was actually detected is used. Thus, the shift amount (offset) and the rotation amount are obtained.

  When performing global alignment with a recipe created from CAD data, a deviation 704 as shown in FIG. 1 occurs between the coordinates of the CAD data and the pattern coordinates of the wafer held on the stage of the pattern inspection apparatus. . Therefore, as shown in FIG. 7, even if the image is moved to the coordinates 701 designated as the global alignment point in the recipe and imaged, the target pattern 703 may not exist in the imaging range 702 of the pattern inspection apparatus.

  Therefore, in the present invention, global alignment is performed using the global alignment processing flow using a plurality of candidates in FIG.

  First, in step 801, the stage of the pattern inspection apparatus is moved to the coordinates of the first candidate pattern for matching at the global alignment point, imaging is performed there (802), and the matching information created from the CAD data in step 803 is used. Pattern matching. If the pattern matching is successful, the coordinates of the matching position are acquired from the pattern inspection apparatus.

  If the pattern matching fails, in step 801, it moves to the coordinates of the next pattern candidate for matching, and performs imaging (802) and pattern matching (803) there. The processing from step 801 to step 803 is repeated for the number of maximum matching pattern candidates, or pattern matching is successful.

  If pattern matching fails for all the matching pattern candidates at a certain global alignment point, the recipe is temporarily stopped in step 804 and the pattern designation of the operator is waited. At this time, as shown in FIG. 10, the matching pattern image 1001 created from the CAD data and the captured image 1002 are displayed side by side. Here, the image of the matching pattern to be displayed may be an image of any number of candidate patterns.

  The operator visually searches for a pattern on the captured image while referring to the displayed image of the matching pattern. If the target pattern does not exist on the captured image, the imaging position is moved using the input device of the pattern inspection apparatus. When the target pattern is found in the captured image, the operator uses the cursor 1003 linked to the pointing device of the pattern inspection device to specify the position corresponding to the mark 1004 on the matching pattern image on the captured image. To do. After the designation, in step 807, the pattern inspection apparatus acquires the coordinates of the designated position on the captured image.

  If pattern matching is successful with any of the matching pattern candidates, the coordinates of the matching position are acquired. The processing from step 801 to step 807 is repeated for the number of global alignment points.

  If pattern matching with the pattern candidate for matching is successful at the first global alignment point, the process from step 801 to step 803 is not repeated at the second and subsequent global alignment points. By performing matching only with matching pattern candidates that have been successfully matched at the global alignment point, the global alignment processing can be shortened.

  When the matching at all global alignment points or the operator's pattern specification is completed, the process proceeds to step 809, where there is a pattern that has been successfully matched or the coordinates obtained from the CAD data of the pattern specified by the operator and the pattern actually exists. Using the coordinates of the position pattern inspection device, the shift amount and the rotation amount are obtained.

  At this time, it is possible to obtain only the shift amount by using only the coordinates of the first global alignment point without using the coordinates of all the global alignment points. If the amount of rotation is very small, it is sufficient to correct only the amount of deviation.

  The obtained deviation amount, rotation amount, and pattern candidate for matching that has succeeded in pattern matching are stored in the recipe or in the pattern inspection apparatus.

  In the processing flow of FIG. 8, the matching pattern candidates are matched in order of priority for each global alignment point. First, as shown in the processing flow of FIG. Is used to perform matching at all global alignment points.If successful, the displacement and rotation are corrected.If unsuccessful, the next matching pattern candidate is used to match at all global alignment points. The same effect can be obtained even in the sequence of executing the above. 9, the processing from step 901 to step 903 corresponds to the processing from step 801 to step 803 in FIG. 8, and the processing from step 904 to step 909 corresponds to the processing from step 904 to step 909 in FIG. .

  Next, when this recipe is executed, the shift amount is used to move to the global alignment point. As a result, since the global alignment point falls within the imaging range of the movement destination, pattern matching is likely to succeed, and the recipe can be automated. In pattern matching, pattern matching may be executed using only the matching pattern that has been successfully matched in the flow of FIGS. For example, if there is a pattern matching pattern as shown in FIG. 11, the pattern matching succeeds in pattern 1101 and the pattern matching fails in pattern 1102 according to the flow of FIGS. 8 and 9, then this recipe is executed. In doing so, it is only necessary to perform pattern matching only on the pattern 1101. As a result, the processing time of the global alignment process can be shortened. This process can be performed by changing the global alignment execution condition registered in the recipe. That is, information on a plurality of alignment patterns registered with priority for one global alignment point may be replaced with information (pattern image and coordinates) of one pattern that has been successfully matched with a pattern. . This replacement may be performed automatically, or may be performed semi-automatically through a process for obtaining operator confirmation.

  Further, as shown in FIG. 12, the deviation amount and rotation amount obtained at the time of executing the recipe are stored in a device having a function of creating a recipe from CAD data, such as a pattern inspection device, and then the device uses the CAD data to create a recipe. 6 is used as a coefficient when calculating the coordinates of the global alignment point and the inspection target pattern from the CAD data, it is possible to automate a simple global alignment according to the flow of FIG.

The figure which shows the shift | offset | difference of the coordinate on CAD data, and the coordinate of a pattern inspection apparatus. Explanatory drawing of a recipe and the parameter contained in it. The figure which shows the example of the pattern for pattern matching of a global alignment point. The figure which shows the example of the pattern image for matching. The processing flow figure of the recipe in a pattern inspection apparatus. The figure which shows the processing flow of global alignment. The figure which shows an example of the relationship between the coordinate of the global alignment point designated by the recipe, and the position where a pattern actually exists. The processing flow figure of global alignment using a plurality of candidates. The processing flow figure of global alignment using a plurality of candidates. The figure which shows the example which displayed the image of the pattern for matching, and the captured image side by side. Explanatory drawing of the pattern for pattern matching on the test object sample. The data flow figure of deviation | shift amount and rotation amount.

Explanation of symbols

101 Coordinate system of CAD data 102 Coordinate system 103 of pattern inspection apparatus 103 Deviation amount of coordinate system shown by 101 and coordinate system shown by 102 104 Amount of rotation 301 between coordinate system shown by 101 and coordinate system shown by 102 Candidate pattern for matching 1
302 Matching pattern candidate 2
303 Matching pattern candidate 3
401 display image for matching pattern candidate 1 402 display image for matching pattern candidate 2 403 display image for matching pattern candidate 3 mark 701 indicating the position indicated by the coordinates 701 Designated by the coordinates of the global alignment point in the recipe Position 702 Imaging range 703 Position 704 where the pattern actually exists. Deviation amount 1001 between the coordinates specified in the recipe and the coordinates where the pattern actually exists 1001 Example of matching pattern image created from CAD data 1002 On the pattern inspection apparatus 1003 Example of image captured in 1003 Cursor 1004 linked to pointing device Mark 1101 on matching pattern image 1101 Pattern that succeeded in pattern matching 1102 Pattern that failed in pattern matching

Claims (8)

In a pattern inspection method for inspecting a pattern formed on a semiconductor wafer with a pattern inspection apparatus,
The pattern inspection apparatus comprises:
A step of reading a plurality of matching patterns created from CAD data of a pattern in a semiconductor chip as a pattern for matching a global alignment point of a semiconductor wafer to be tested and a recipe in which coordinates thereof are registered with priority,
Moving the field of view to a plurality of global alignment points registered in the recipe, and using the plurality of registered matching patterns in order of priority to perform pattern matching with a pattern on the semiconductor wafer to be tested;
Performing global alignment using the coordinates of the pattern detected by the pattern matching and the coordinates on the CAD data, obtaining a shift amount and a rotation amount between the coordinates of the CAD data and the coordinates of the pattern device,
The pattern inspection method characterized by performing. In the pattern inspection method according to claim 1, when pattern matching fails in all matching patterns registered for one global alignment point,
A step of displaying a pattern for matching created from the CAD data and an image captured by the pattern inspection apparatus;
Receiving an instruction to instruct a pattern corresponding to a matching pattern on the captured image;
Performing the step of obtaining the coordinates of the indicated pattern;
A pattern inspection method using the acquired coordinates as coordinates of a pattern detected by the pattern matching. The pattern inspection method according to claim 1,
Executing the step of registering the obtained deviation amount and rotation amount in the recipe;
The pattern inspection method, wherein the next time the recipe is read and the field of view is moved to the global alignment point registered in the recipe, the pattern is moved to a point reflecting the registered shift amount and rotation amount.   The pattern inspection method according to claim 1, wherein the obtained deviation amount and rotation amount are stored, and when the next recipe is created, the stored deviation amount and rotation amount are reflected in the coordinates of the global alignment point. Characteristic pattern inspection method.   The pattern inspection method according to claim 1, wherein information on a plurality of matching patterns registered in the recipe with priority given to one global alignment point corresponds to the pattern detected by the pattern matching. A pattern inspection method comprising a step of replacing with information on one matching pattern. Selecting a plurality of patterns as matching patterns for global alignment points from the CAD data of the patterns in the semiconductor chip formed on the semiconductor wafer, registering them in the recipe with priorities, and
Executing the recipe by a pattern inspection apparatus, moving the field of view of the pattern inspection apparatus to a global alignment point registered in the recipe, and performing pattern matching using the registered matching patterns in order of priority;
Performing global alignment using the coordinates of the pattern and CAD data detected by the pattern matching;
A pattern inspection method comprising: In the pattern inspection method according to claim 6, when pattern matching fails in all matching patterns registered for one global alignment point,
A step of displaying a pattern for matching created from the CAD data and an image captured by the pattern inspection apparatus;
Receiving an instruction to instruct a pattern corresponding to a matching pattern on the captured image;
Obtaining the coordinates of the instructed pattern,
A pattern inspection method using the acquired coordinates as coordinates of a pattern detected by the pattern matching.   The pattern inspection method according to claim 6, wherein information on a plurality of matching patterns registered in the recipe with a priority for one global alignment point corresponds to the pattern detected by the pattern matching. A pattern inspection method comprising a step of replacing with information on one matching pattern.

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