CDU mark and method for carrying out CDU correction by using same

Abstract

The invention provides a CDU mark which is composed of a plurality of patterns with the size of 5 micrometers * 5 micrometers, the patterns are arranged into a 7 * 7 matrix, the patterns in each column of the matrix are the same patterns, and the patterns are selected from process hot spot patterns needing to be formed in a wafer. The morphology of the pattern in the CDU mark used by the CDU correction is closer to the process hot spot pattern in the pattern in the wafer, the degree that the critical dimension of the pattern in the wafer deviates from the target value can be truly reflected, and the uniformity of the critical dimension of the pattern in the wafer can be more effectively improved through the CDU correction.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a CDU marker and a method for performing CDU correction using the marker. Background Art

[0002] Photolithography and etching processes are the basic and core processes used to manufacture semiconductor devices. The photolithography process uses the geometric patterns on the mask to transfer the corresponding patterns to the photosensitive film layer (photoresist) covering the semiconductor wafer through photochemical reactions. However, the pattern on the photosensitive film layer is not the final part of the semiconductor device, but only the mold of the final circuit pattern. The etching process is used for pattern transfer (Pattern Transfer), thereby forming a semiconductor pattern structure on the device layer.

[0003] Even if the pattern on the photoresist layer is aligned with the pattern on the alignment layer (theoretically, the overlay error is zero), the semiconductor pattern etched on the device layer will still deviate from the expected position, resulting in poor critical dimension uniformity (CDU) of the semiconductor pattern. The device yield loss caused by the uneven distribution of critical dimension (CD) is corrected by CDU correction. The existing CDU correction process is usually as follows: after the wafer is exposed for the first time by the lithography machine, it passes through the subsequent etching machine, and CDU data is obtained through CDU measurement; these data are processed by the software configured by the lithography machine (such as ASML IMO software) to obtain a correction recipe, and the CDU is corrected when the subsequent wafer is exposed using the recipe with this correction information.

[0004] The existing CDU measurement method generally measures the CDU marks set on the wafer dicing lanes, and realizes CDU correction by placing more marks to cover the test points (shots) used to set specific energy and focal length in the lithography process applied to the entire product. The existing CDU marks are basically one-dimensional dense lines or trench patterns, which are inconsistent with the failed graphics, that is, the CDU mark data obtained through CDU measurement cannot truly reflect the degree to which the critical dimension of the graphics deviates from the target value. Summary of the invention

[0005] In view of the shortcomings of the prior art described above, the purpose of the present application is to provide a CDU mark and a method for CDU correction using the mark, so as to solve the problem in the prior art that the CDU mark is inconsistent with the failed pattern, resulting in the CDU mark data obtained through CDU measurement not being able to truly reflect the degree to which the critical dimension of the pattern deviates from the target value.

[0006] To achieve the above-mentioned purpose and other related purposes, the present application provides a CDU mark, which is composed of multiple graphics with a size of 5μm×5μm, and the graphics are arranged in a 7×7 matrix. The graphics in each column of the matrix are graphics with the same pattern, and the graphics are selected from the process hotspot graphics that need to be formed in the wafer.

[0007] Preferably, the size of the matrix frame does not exceed 42 μm×42 μm.

[0008] Preferably, the process hot spot pattern includes a pattern formed in the edge area of ​​the wafer, a pattern with a corner, or a pattern with a step height difference.

[0009] The present application also provides a method for performing CDU correction using the above-mentioned CDU mark, comprising:

[0010] Step 1, setting the CDU marks at equal intervals on the wafer dicing lanes;

[0011] Step 2, performing OPC correction on the pattern in the CDU mark in the same manner as the pattern in the wafer to determine a critical dimension target value of the pattern in the CDU mark;

[0012] Step 3, after photolithography and etching are performed on the wafer, the critical dimension measurement value of the pattern in the CDU mark is obtained through CDU measurement;

[0013] Step 4, taking the difference between the critical dimension measurement value of the failure pattern in the CDU mark and the corresponding critical dimension target value obtained in step 2 as CDU correction data;

[0014] Step 5: Perform CDU correction based on the CDU correction data obtained in step 4.

[0015] Preferably, the equipment for performing CDU measurement in step 3 comprises a critical dimension scanning electron microscope.

[0016] Preferably, the critical dimension of the pattern includes the line width or hole diameter of the pattern.

[0017] Preferably, the R value in the correction value used when performing CDU correction in step 5 is the average value of the R values ​​of all graphics in the CDU mark obtained by CDU measurement.

[0018] Preferably, the upper and lower limits of the correction value are set to the EL value of PWQ of the same type of product.

[0019] As described above, the CDU mark provided in the present application and the method for CDU correction using the mark have the following beneficial effects: the morphology of the graphics in the CDU mark used for CDU correction is closer to the process hotspot graphics in the graphics within the wafer, and can truly reflect the degree to which the critical dimension of the graphics within the wafer deviates from the target value. Through CDU correction, the critical dimension uniformity of the graphics within the wafer can be more effectively improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 A schematic diagram showing a CDU marking provided in an embodiment of the present application;

[0022] Figure 2 Display is provided for the use of the embodiment of the present application Figure 1 The CDU mark shown is a flowchart of a method for performing CDU correction. DETAILED DESCRIPTION

[0023] The following describes the implementation of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. The present application can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0024] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in this application. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0025] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating directions or positional relationships, are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0026] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can also be the internal connection of two components, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0027] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0028] The existing CDU mark is basically a one-dimensional dense line or groove pattern, which is inconsistent with the failed pattern. That is, the CDU mark data obtained by CDU measurement cannot truly reflect the degree to which the critical dimension of the pattern deviates from the target value.

[0029] In order to solve this problem, the present application provides a CDU marker.

[0030] See also Figure 1 , which shows a schematic diagram of the CDU marking provided in an embodiment of the present application.

[0031] like Figure 1 As shown, the CDU mark is composed of multiple graphics with a size of 5μm×5μm (micrometers), which are arranged in a 7×7 matrix, and the graphics in each column of the matrix are graphics with the same pattern. The graphics are selected from the process hotspot graphics that need to be formed in the wafer, that is, graphics with critical dimensions that deviate greatly from the target value based on previous process experience, such as graphics formed in the edge area of ​​the wafer, graphics with corners, graphics with step height differences, etc. The process hotspot graphics formed in the wafer are cut into 5μm×5μm, and then the CDU mark is formed according to the above arrangement rules. The size of the matrix frame does not exceed 42μm×42μm. If it exceeds this size, the CDU mark cannot be set on the wafer cutting path.

[0032] This application also provides a method for using the CDU mark to perform CDU correction, see Figure 2 , which shows a flow chart of a method for performing CDU correction using the CDU marker provided in an embodiment of the present application.

[0033] like Figure 2 As shown, the method comprises the following steps:

[0034] Step 1, setting the CDU marks at equal intervals on the wafer dicing lanes;

[0035] Step 2, performing OPC correction on the pattern in the CDU mark in the same manner as the pattern in the wafer to determine a critical dimension target value of the pattern in the CDU mark;

[0036] Step 3, after photolithography and etching are performed on the wafer, the critical dimension measurement value of the pattern in the CDU mark is obtained through CDU measurement;

[0037] Step 4, taking the difference between the critical dimension measurement value of the failure pattern in the CDU mark and the corresponding critical dimension target value obtained in step 2 as CDU correction data;

[0038] Step 5: Perform CDU correction based on the CDU correction data obtained in step 4.

[0039] In step one, the CDU marks are arranged at equal intervals on the wafer dicing paths, which can subsequently fully reflect the critical dimension deviation of the graphics with the same pattern located in the wafer edge area and the wafer center area.

[0040] In step 2, since the pattern in the CDU mark is selected from the process hot spot pattern to be formed in the wafer, it is necessary to perform OPC correction on the pattern in the CDU mark in the same manner as the pattern in the wafer to determine a more reasonable critical dimension target value.

[0041] OPC correction can be rule-based OPC or model-based OPC, and the specific process will not be described here.

[0042] In step 3, the equipment for performing CDU measurement includes a critical dimension scanning electron microscope (CD-SEM), and the critical dimension of the pattern includes the line width, aperture, etc. of the pattern.

[0043] In step 4, the failure pattern in the CDU mark refers to a pattern in which the difference between the critical dimension measurement value and the corresponding critical dimension target value exceeds a preset threshold. According to the location of the failure pattern on the wafer, a distribution map of the CDU correction data can be obtained.

[0044] In step 5, the R value in the correction value used when implementing CDU correction is the average value of the R values ​​of all graphics in the CDU mark obtained through CDU measurement, and the upper and lower limits of the correction value are set to the EL value of PWQ (process window verification) of the same type of product.

[0045] After CDU correction is implemented through the software configured in the lithography machine (such as ASMLIMO software), a correction recipe is obtained, and the CDU is corrected when the subsequent wafer is exposed using this recipe.

[0046] It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present application in a schematic manner. Therefore, the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0047] In summary, the CDU mark provided by the present application and the method for CDU correction using the mark, the morphology of the pattern in the CDU mark used for CDU correction is closer to the process hot spot pattern in the wafer pattern, and can truly reflect the degree to which the critical dimension of the wafer pattern deviates from the target value. Through CDU correction, the critical dimension uniformity of the wafer pattern can be more effectively improved. Therefore, the present application effectively overcomes various shortcomings in the prior art and has a high industrial utilization value.

[0048] The above embodiments are merely illustrative of the principles and effects of the present application and are not intended to limit the present application. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed by the present invention shall still be covered by the claims of the present application.

Claims

1. A CDU marker, characterized in that: The CDU mark is composed of a plurality of graphics with a size of 5 μm×5 μm, and the graphics are arranged in a 7×7 matrix. The graphics in each column of the matrix are graphics with the same pattern, and the graphics are selected from process hot spot graphics that need to be formed in the wafer.

2. The CDU marker according to claim 1, characterized in that: The size of the matrix frame does not exceed 42 μm×42 μm.

3. The CDU marker according to claim 1, characterized in that: The process hot spot pattern includes a pattern formed in the edge area of ​​a wafer, a pattern with a corner, or a pattern with a step height difference.

4. A method for CDU correction using the CDU marker according to any one of claims 1 to 3, characterized in that: The method comprises: Step 1, setting the CDU marks at equal intervals on the wafer dicing lanes; Step 2, performing OPC correction on the pattern in the CDU mark in the same manner as the pattern in the wafer to determine the critical dimension target value of the pattern in the CDU mark; Step 3, after performing photolithography and etching on the wafer, obtaining the critical dimension measurement value of the pattern in the CDU mark through CDU measurement; Step 4, taking the difference between the critical dimension measurement value of the failure pattern in the CDU mark and the corresponding critical dimension target value obtained in step 2 as CDU correction data; Step 5: Perform CDU correction based on the CDU correction data obtained in step 4.

5. The method according to claim 4, characterized in that The equipment for performing CDU measurement in step 3 includes a critical dimension scanning electron microscope.

6. The method according to claim 4, characterized in that The critical dimension of the pattern includes the line width or hole diameter of the pattern.

7. The method according to claim 4, characterized in that The R value in the correction value used when performing CDU correction in step 5 is the average value of the R values ​​of all graphics in the CDU mark obtained through the CDU measurement.

8. The method according to claim 7, characterized in that The upper and lower limits of the correction value are set to the EL value of PWQ of the same type of product.

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