CN117826523A - Photomask and method for manufacturing the same - Google Patents

Photomask and method for manufacturing the same Download PDF

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Publication number
CN117826523A
CN117826523A CN202211185327.1A CN202211185327A CN117826523A CN 117826523 A CN117826523 A CN 117826523A CN 202211185327 A CN202211185327 A CN 202211185327A CN 117826523 A CN117826523 A CN 117826523A
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test pattern
target
design
design value
critical dimension
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周冠廷
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Changxin Memory Technologies Inc
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Changxin Memory Technologies Inc
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Abstract

Embodiments of the present disclosure provide a photomask and a method for manufacturing a photomask, wherein the method for manufacturing a photomask includes: acquiring a measurement value of a critical dimension and a design value of the critical dimension of each test pattern in a test pattern set positioned in a non-exposure area of a current photomask; the current photomask is prepared based on a first design data file; comparing the measured value of the critical dimension of each test pattern with the design value of the critical dimension to obtain a first comparison result; determining a target graph set corresponding to an exposure area in the first design data file and an adjustment value corresponding to a design value of a critical dimension of each target graph in the target graph set based on the first comparison result; updating the first design data file based on the adjustment value corresponding to the design value of the critical dimension of each target graph to obtain a second design data file; and preparing the target photomask based on the second design data file.

Description

Photomask and method for manufacturing the same
Technical Field
The present disclosure relates to the field of semiconductor fabrication, and relates to, but is not limited to, a photomask and a method of making a photomask.
Background
When the optical proximity correction (Optical Proximity Correction, OPC) is used for data processing, tiny patterns are added around sparse patterns in the integrated circuit design layout, so that the sparse patterns can look like dense patterns in an optical angle, and the tiny patterns must be smaller than the resolution of a photoetching machine. These patterns are only scattered by the light when exposed and are not transferred to the photoresist, and are therefore called Sub-resolution assist patterns (Sub-resolution Assistant Feature, SRAF) or Scattering bars (Scattering bars).
However, when the design value of the critical dimension (Critical Dimension, CD) of the SRAF is too small, the SRAF on the photomask will be broken or insufficient in resolution when the design value exceeds the process capability of the photomask, which directly affects the OPC effect and the difficulty of photomask inspection.
Disclosure of Invention
Embodiments of the present disclosure provide a photomask and a method of manufacturing a photomask.
In one aspect, embodiments of the present disclosure provide a method of preparing a photomask, the method comprising: acquiring a measurement value of a critical dimension and a design value of the critical dimension of each test pattern in a test pattern set positioned in a non-exposure area of a current photomask; the current photomask is prepared based on a first design data file; comparing the measured value of the critical dimension of each test pattern with the design value of the critical dimension to obtain a first comparison result; determining a target graph set corresponding to an exposure area in the first design data file and an adjustment value corresponding to a design value of a critical dimension of each target graph in the target graph set based on the first comparison result; updating the first design data file based on the adjustment value corresponding to the design value of the critical dimension of each target graph to obtain a second design data file; and preparing the target photomask based on the second design data file.
In some embodiments, the determining, based on the first comparison result, a target graphic set of the corresponding exposure area in the first design data file includes: determining a target design value based on the first comparison result; the target design value is a design value of a critical dimension of a target test pattern in the test pattern set, and the measurement value of the critical dimension of the target test pattern is smaller than the design value of the critical dimension; determining a union set of sub-resolution auxiliary graphs meeting a first preset condition in the first design data file as the target graph set; the first preset condition includes that a design value of a critical dimension of the first design data file corresponding to an exposure area is smaller than the target design value.
In some embodiments, the test pattern set includes a first test pattern set and a second test pattern set; the first test pattern set comprises a plurality of first test patterns extending along the vertical direction, and the design value of the critical dimension of each first test pattern in the horizontal direction is the same as one preset design value in a preset design value set; the second test pattern set comprises a plurality of second test patterns extending along the horizontal direction, and the design value of the critical dimension of each second test pattern in the vertical direction is the same as one preset design value in the preset design value set.
In some embodiments, the first test pattern set includes a plurality of first test pattern groups, each of the first test pattern groups corresponds to one of the preset design values in the preset design value set, and the design value of the critical dimension of each of the first test patterns in the same first test pattern group in the horizontal direction is the same as the preset design value corresponding to the first test pattern group; the second test pattern set comprises a plurality of second test pattern groups, each second test pattern group corresponds to one preset design value in the preset design value set, and the design value of the critical dimension of each second test pattern in the same second test pattern group in the vertical direction is the same as the preset design value corresponding to the second test pattern group.
In some embodiments, the target design value comprises a first target design value; determining a target design value based on the first comparison result, including: determining a first target design value based on the first comparison result; the first target design value is a preset design value corresponding to a target first test pattern group in the first test pattern set, and the measurement value of the critical dimension of the target first test pattern group is smaller than the preset design value corresponding to the target first test pattern group; determining the union of sub-resolution auxiliary graphs meeting a first preset condition in the first design data file as the target graph set, wherein the method comprises the following steps: determining a union set of sub-resolution auxiliary graphs meeting a first sub-preset condition in the first design data file as the target graph set; the first sub-preset condition includes that a design value of a critical dimension extending in a vertical direction in the first design data file corresponding to an exposure area is smaller than the first target design value.
In some embodiments, the target design value comprises a second target design value; determining a target design value based on the first comparison result, including: determining a second target design value based on the first comparison result; the second target design value is a preset design value corresponding to a target second test pattern group in the second test pattern set, and the measurement value of the critical dimension of the target second test pattern group is smaller than the preset design value corresponding to the target second test pattern group; determining the union of sub-resolution auxiliary graphs meeting a first preset condition in the first design data file as the target graph set, wherein the method comprises the following steps: determining a union set of sub-resolution auxiliary graphs meeting a second sub-preset condition in the first design data file as the target graph set; the second sub-preset condition includes that a design value of a critical dimension extending in a horizontal direction in the first design data file corresponding to the exposure area is smaller than the second target design value.
In some embodiments, each of the first test patterns has a dimension in the vertical direction ranging from 5 micrometers to 15 micrometers; each of the second test patterns has a dimension in the horizontal direction ranging from 5 micrometers to 15 micrometers.
In some embodiments, where the current mask is a bright field mask, the first test pattern and the second test pattern each comprise a line pattern; in the case where the current mask is a dark field mask, the first test pattern and the second test pattern each include a void pattern.
In some embodiments, the set of preset design values includes at least one of the following preset design values: 40 nm, 42 nm, 44 nm, 46 nm, 48 nm, 50 nm, 52 nm, 54 nm, 56 nm, 58 nm, 60 nm, 64 nm, 68 nm, 72 nm, 80 nm, 92 nm, 100 nm and 120 nm.
In some embodiments, each first test pattern group includes N first test pattern subsets, where an nth first test pattern subset includes one first test pattern, an ith first test pattern subset includes at least one first test pattern uniformly arranged along a horizontal direction, a space between the first test patterns in the ith first test pattern subset is smaller than a space between the first test patterns in the (i+1) th first test pattern subset, N is a positive integer greater than 1, and i is a positive integer smaller than N-1; each second test pattern group comprises M second test pattern subsets, wherein the M second test pattern subsets comprise one second test pattern, the j second test pattern subsets comprise at least one second test pattern uniformly distributed along the vertical direction, the interval between the second test patterns in the j second test pattern subsets is smaller than the interval between the second test patterns in the j+1th second test pattern subsets, M is a positive integer larger than 1, and j is a positive integer smaller than M-1.
In some embodiments, the spacing S between two adjacent first test patterns in the (i+1) -th first test pattern subset i+1 ＝((1+p) i -1)×CD k +(1+p) i ×S 1 The method comprises the steps of carrying out a first treatment on the surface of the The interval L between two adjacent second test patterns in the j+1th second test pattern subset j+1 ＝((1+q) j -1)×CD m ＇+(1+q) j ×L 1 The method comprises the steps of carrying out a first treatment on the surface of the Wherein, CD k A design value for the critical dimension of the first test pattern in the kth first test pattern group; CD (compact disc) m ' is the design value of the critical dimension of the second test pattern in the mth second test pattern group; p is a positive integer not exceeding (R-3)/2, R is the total number of first test patterns in the 1 st first test pattern subset; q is a positive integer not exceeding (T-3)/2, T is the total number of second test patterns in the 1 st second test pattern subset, and R and T are integers greater than or equal to 5; the S is 1 A spacing between two adjacent first test patterns in the 1 st first test pattern subset; the L is 1 Is the spacing between two adjacent second test patterns in the 1 st subset of second test patterns.
In some embodiments, the N first test pattern subsets are arranged sequentially in a vertical direction; each first test pattern in the (i+1) th first test pattern subset is respectively connected with each first test pattern of p first test patterns in the (i) th first test pattern subset in sequence at intervals one by one; the M second test pattern subsets are sequentially arranged along the horizontal direction; each second test pattern in the j+1th second test pattern subset is respectively connected with each second test pattern of the q second test patterns in the j second test subset in sequence at intervals.
In some embodiments, determining the union of sub-resolution auxiliary graphics satisfying a first preset condition in the first design data file as the target graphics set includes: taking the extending direction of the test pattern corresponding to the target design value and the interval between two adjacent test patterns with the target design value as a target extending direction and a target interval respectively; determining a union of sub-resolution auxiliary graphs of which the first design data file meets a third sub-preset condition as the target graph set; the third sub-preset condition includes that a design value of a critical dimension corresponding to an exposure area in the first design data file is smaller than the target design value, an interval between two adjacent sub-resolution auxiliary patterns is the target interval, and an extending direction is the target extending direction.
In some embodiments, the updating the first design data file based on the adjustment value corresponding to the design value of the critical dimension of each target graphic to obtain a second design data file includes: adjusting the coordinate information of each target graph based on an adjustment value corresponding to a design value of the critical dimension of each target graph to obtain the adjusted coordinate information of each target graph; and updating the first design data file based on the coordinate information of each target graph after adjustment to obtain the second design data file.
In some embodiments, the updating the first design data file based on the adjusted coordinate information of each target graphic to obtain the second design data file includes: dividing the first design data file into a first design data subfile and a second design data subfile; wherein the first design data subfile includes the target set of graphics and the second design data subfile includes graphics other than the target set of graphics in the total set of graphics in the first design data file; updating the first design data subfile based on the coordinate information of each target graph after adjustment to obtain a third design data subfile; and obtaining the second design data file based on the third design data subfile and the second design data subfile.
In some embodiments, the adjusting the coordinate information of each target graph based on the adjustment value corresponding to the design value of the critical dimension of each target graph to obtain the adjusted coordinate information of each target graph includes: for the target graphics extending in the vertical direction in the target graphics set, adjusting the abscissa in the coordinate information of each target graphics based on the adjustment value corresponding to the design value of the key size of each target graphics to obtain the coordinate information of each target graphics after adjustment; and/or, for the target graphics extending along the horizontal direction in the target graphics set, adjusting the ordinate in the coordinate information of each target graphics based on the adjustment value corresponding to the design value of the critical dimension of each target graphics, so as to obtain the adjusted coordinate information of each target graphics.
In some embodiments, the method further comprises: comparing the measured value of the critical dimension of the sub-resolution auxiliary graph in the target photomask with the design value of the critical dimension to determine a second comparison result; obtaining a defect detection result of the target photomask; and determining that the target photomask is a qualified photomask under the condition that the second comparison result meets a preset threshold value and the defect detection result of the target photomask is that no defect exists.
In another aspect, an embodiment of the present disclosure provides a photomask, which is manufactured by using the method for manufacturing a photomask according to any of the embodiments above, where the photomask has an exposed area and a non-exposed area, the exposed area includes a target photomask pattern and at least one sub-resolution auxiliary pattern, and the non-exposed area includes a test pattern set.
In an embodiment of the disclosure, a first comparison result of a measured value of a critical dimension of a test pattern in a non-exposed area of a current photomask and a design value of the critical dimension is used to reflect a process capability range of a photomask plant; determining a target graph set in the first design data file and an adjustment value corresponding to a design value of a key size of each target graph in the target graph set based on the first comparison result; then, updating the first design data file based on the adjustment value corresponding to the design value of the critical dimension of each target graph to obtain a second design data file; finally, the target photomask is prepared based on the second design data file, so that the key size of the target pattern on the target photomask can be closer to the initial design value, the situation that the target pattern is broken or insufficient in analysis and other defects can be reduced, and the accuracy of the follow-up OPC based on the target photomask can be improved.
Drawings
In the drawings (which are not necessarily drawn to scale), like numerals may describe similar components in different views. Like reference numerals having different letter suffixes may represent different instances of similar components. The drawings illustrate generally, by way of example and not by way of limitation, various embodiments discussed herein.
Fig. 1 is a schematic implementation flow diagram of a method for manufacturing a photomask according to an embodiment of the disclosure;
FIG. 2 is a schematic diagram of a structure of a current photomask according to an embodiment of the present disclosure;
FIG. 3 is a schematic diagram of a test pattern set according to an embodiment of the present disclosure;
FIG. 4 is a schematic diagram of another test pattern set according to an embodiment of the present disclosure;
FIG. 5 is a schematic structural diagram of a first test pattern group according to an embodiment of the disclosure;
FIG. 6 is a schematic diagram of another first test pattern group according to an embodiment of the disclosure;
FIG. 7 is a schematic diagram of a second test pattern set according to an embodiment of the disclosure;
FIG. 8 is a schematic diagram of a first test pattern group according to an embodiment of the present disclosure;
FIG. 9 is a schematic diagram of a second test pattern set according to an embodiment of the disclosure;
FIG. 10 is a schematic diagram of a pattern in a current photomask according to an embodiment of the present disclosure;
FIG. 11 is a schematic diagram of adjusting design values of critical dimensions of sub-resolution assist features according to an embodiment of the present disclosure;
fig. 12 is a schematic diagram of defect conditions of a target mask and sub-resolution auxiliary patterns in the target mask according to the related art and the embodiments of the present disclosure.
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the specific embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present disclosure. However, it will be apparent to one skilled in the art that the present disclosure may be practiced without one or more of these details. In other instances, well-known features have not been described in order to avoid obscuring the present disclosure; that is, not all features of an actual implementation are described in detail herein, and well-known functions and constructions are not described in detail.
In the drawings, the size of layers, regions, elements and their relative sizes may be exaggerated for clarity. Like numbers refer to like elements throughout.
It will be understood that when an element or layer is referred to as being "on" … …, "" adjacent to "… …," "connected to" or "coupled to" another element or layer, it can be directly on, adjacent to, connected to or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on" … …, "" directly adjacent to "… …," "directly connected to" or "directly coupled to" another element or layer, there are no intervening elements or layers present. It will be understood that, although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present disclosure. When a second element, component, region, layer or section is discussed, it does not necessarily mean that the first element, component, region, layer or section is present in the present disclosure.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of the associated listed items.
Embodiments of the present disclosure provide a method for preparing a photomask, referring to fig. 1, the method including steps S101 to S105, wherein:
step S101, obtaining a measurement value of a critical dimension and a design value of the critical dimension of each test pattern in a test pattern set positioned in a non-exposure area of a current photomask; the current photomask is prepared based on the first design data file;
here, referring to fig. 2, the current mask 20 may include a non-exposure region 21 and an exposure region 22, the exposure region 22 including at least one sub-resolution assist pattern 201 and a target mask pattern 202 to be transferred onto a wafer; the non-exposed area 21 may include at least one test pattern set 10, the test pattern set 10 may be located in a space available in the non-exposed area, and the non-exposed area 21 may further include a marking pattern. Wherein the test pattern set 10 is a union set of at least one test pattern, and the test pattern set 10 may be formed by transferring pattern data in the test pattern set in the first design data file onto the current photomask; the test patterns are used to test the process capability range or process variation (Mask Shop Process Bias, MSPB) of the reticle factory. Different test patterns can correspond to design values of different critical dimensions; different test patterns may also correspond to the same design values of critical dimensions, and the comparison of the embodiments of the present disclosure is not limited.
The CD measurements may be CD measurements measured by a scanning electron microscope (Critical Dimension Scanning Electron Microscope, CD-SEM) for CD measurements at a reticle factory. The design value of the critical dimension may be a target critical dimension, and the design value of the critical dimension may be determined according to coordinate information in graphic data of a corresponding test graphic in the first design data file, for example, if the test graphic is rectangular, coordinates of four points of the rectangle are (X1, Y1), (X2, Y2), and (X1, Y2) in order, the design value of the critical dimension of the test graphic in the horizontal direction may be X2-X1, and the design value of the critical dimension of the test graphic in the vertical direction may be Y2-Y1.
The first design data file may be obtained by adding a test pattern set to a non-exposure area corresponding to the initial design data file, where the initial design data file may include pattern data of an exposure area in the current photomask, and the pattern data may include coordinate information of a plurality of patterns defined in the exposure area. The first design data file may also be a combination of a design data file including graphic data of a test graphic set of non-exposed areas and a design data file including graphic data of exposed areas. The format of the first design data file may be a graphic data description language file format commonly used in integrated circuit layout designs, such as a GDS format file or an OASIS format file, etc.
Step S102, comparing the measured value of the critical dimension of each test pattern with the design value of the critical dimension to obtain a first comparison result;
here, the first comparison result may be used to reflect the process capability range of the MSPB or the reticle factory. The first comparison result may be a difference between the measured value of the critical dimension of each test pattern and the design value of the critical dimension of the test pattern; the larger the absolute value of the difference, the larger the process difference of the mask shop or the smaller the process capability range of the mask shop.
Because of the small process capability of some photomask factories, the measured value of the critical dimension of some test patterns on the prepared photomask is different from the design value of the critical dimension, for example, the design value of the critical dimension of a certain test pattern in the first design data file is 60 nanometers (nm), and the critical dimension of the corresponding test pattern on the photomask prepared based on the first design data file is 58nm. That is, the process variation of the mask factory is large, so that the critical dimension of the SRAF formed on the mask by the mask factory may be small, and even the defects such as fracture or insufficient resolution may occur, thereby affecting the subsequent OPC effect based on the target mask. Therefore, in order to make the measured value of the critical dimension of the SRAF closer to the design value of the critical dimension, thereby reducing the influence on the OPC effect, it is necessary to adjust the design value of the critical dimension of the SRAF.
Step S103, determining a target graph set corresponding to the exposure area in the first design data file and an adjustment value corresponding to a design value of a critical dimension of each target graph in the target graph set based on the first comparison result;
here, the target pattern set may be a union of target patterns, and the target patterns may be SRAFs located in the first design data file corresponding to the exposure areas. The adjustment value may be set based on the first comparison result and experience, for example, the difference between the measured value of the critical dimension of the test pattern and the design value of the critical dimension is-7, and the adjustment value may be set to +4 with reference to the difference and experience.
In some implementations, the adjustment value corresponding to the design value of the critical dimension of each target pattern may be the same, so that the adjustment process of the design value of the critical dimension of the target pattern may be simplified. In implementation, the absolute value of the average value of the difference between the critical dimension measurement values and the critical dimension design values of different test patterns can be used as the adjustment value corresponding to the critical dimension design value of the target pattern. For example, the critical dimension measurement values of different test patterns are respectively-2, -6, -5 and-7, and the absolute value of the average value is 5, and then the adjustment value corresponding to the design value of the critical dimension of the target pattern is 5.
In other embodiments, the adjustment value corresponding to the design value of the critical dimension of each target pattern may be different, for example, the design value of the critical dimension of the first target pattern and the measurement value of the critical dimension are respectively 60nm and 56nm, and the difference value between them is-4; the design value of the critical dimension of the second target pattern and the measurement value of the critical dimension are respectively 54nm and 50nm, and the difference value of the two is-4; the design value of the critical dimension of the third target pattern and the measurement value of the critical dimension are respectively 48nm and 46nm, and the difference value of the design value and the measurement value is-2; in determining the adjustment value, the adjustment value corresponding to the design value of the critical dimension of the first target pattern may be determined to be +3, the adjustment value corresponding to the design value of the critical dimension of the second target pattern may be determined to be +2, and the adjustment value corresponding to the design value of the critical dimension of the third target pattern may be determined to be +1, that is, the smaller the design value of the critical dimension of the target pattern is, the smaller the corresponding adjustment value is. In this way, the accuracy of the adjustment of the design value of the critical dimension of the target pattern can be improved, thereby further reducing the influence on the OPC effect by the subsequent target mask.
Step S104, updating the first design data file based on the adjustment value corresponding to the design value of the critical dimension of each target graph to obtain a second design data file;
here, updating the first design data file may be a process of increasing the design value of the critical dimension of the target pattern in the target pattern set corresponding to the exposure area in the first design data file, in other words, a process of compensating the design value of the critical dimension of the target pattern in the target pattern set. Therefore, even if the process capability range of some photomask factories is smaller, the defects of fracture, insufficient analysis and the like of the target pattern on the subsequent photomask can be avoided, and the effect of the subsequent OPC based on the target photomask can not be influenced.
Step S105, preparing the target photomask based on the second design data file.
In an embodiment of the disclosure, a first comparison result of a measured value of a critical dimension of a test pattern in a non-exposed area of a current photomask and a design value of the critical dimension is used to reflect a process capability range of a photomask plant; determining a target graph set in the first design data file and an adjustment value corresponding to a design value of a key size of each target graph in the target graph set based on the first comparison result; then, updating the first design data file based on the adjustment value corresponding to the design value of the critical dimension of each target graph to obtain a second design data file; finally, the target photomask is prepared based on the second design data file, so that the key size of the target pattern on the target photomask can be closer to the initial design value, the situation that the target pattern is broken or insufficient in analysis and other defects can be reduced, and the accuracy of the follow-up OPC based on the target photomask can be improved.
In some embodiments, referring to fig. 3, test pattern set 10 includes a first test pattern set 11 and a second test pattern set 12; the first test pattern set 11 includes a plurality of first test patterns 101 extending along a vertical direction, and design values of key dimensions of each first test pattern 101 in a horizontal direction are respectively the same as a preset design value in a preset design value set; the second test pattern set 12 includes a plurality of second test patterns 102 extending in a horizontal direction, and the design value of the critical dimension of each second test pattern 102 in the vertical direction is the same as a preset design value in the preset design value set.
Here, the first test pattern and the second test pattern may be line patterns or void patterns, which the embodiments of the present disclosure are not limited to. In some embodiments, referring to fig. 3, in the case where the current mask is a bright field mask, the first test pattern and the second test pattern each include a line pattern; referring to fig. 4, in case that the current mask is a dark field mask, the first test pattern and the second test pattern each include a void pattern. In fig. 3 and 4, the areas having the filled pattern each represent an opaque area, and the areas having no filled pattern each represent an opaque area.
In the embodiment of the disclosure, the measurement value of the critical dimension and the design value of the critical dimension of the void pattern in the bright field photomask line pattern and the dark field photomask can be obtained, and then the first comparison result is obtained, so that the process range of the photomask factory can be more comprehensively tested, the adjustment value corresponding to the design value of the critical dimension of each target pattern can be more accurately determined, and the accuracy of the subsequent OPC based on the target photomask is further improved.
The design value of the critical dimension of each first test pattern in the horizontal direction is the same as a preset design value in a preset design value set, the design value of the critical dimension of each second test pattern in the vertical direction is the same as a preset design value in a preset design value set, and the elements in the union of the design values of the critical dimension of each first test pattern in the horizontal direction and the elements in the union of the design values of the critical dimension of each second test pattern in the vertical direction are the same as the corresponding elements in the preset design value set.
In this embodiment of the present disclosure, the test pattern set includes a first test pattern set and a second test pattern set, where the first test pattern set includes a plurality of first test patterns extending along a vertical direction, and the second test pattern set includes a plurality of second test patterns extending along a horizontal direction, and then the measured value of the critical dimension and the design value of the critical dimension of the first test pattern and the measured value of the critical dimension and the design value of the critical dimension of the second test pattern can be compared simultaneously, so that the measured value of the critical dimension and the design value of the critical dimension of the test patterns in different directions can be compared, and the obtained first comparison result is more comprehensive. Meanwhile, the element in the union of the design values of the key sizes of the first test patterns in the horizontal direction and the element in the union of the design values of the key sizes of the second test patterns in the vertical direction are the same as the corresponding element in the preset design value set, so that whether the preparation capacity of a photomask factory in different directions is different for the design value of the same key size can be known, and the sub-resolution auxiliary patterns in different directions can be better adjusted.
Referring to fig. 3 or 4, the design values of the critical dimensions in the predetermined set of design values may be critical dimensions of a common pattern in the integrated circuit. In some embodiments, the set of preset design values includes at least one of the following preset design values: 40nm, 42nm, 44nm, 46nm, 48nm, 50nm, 52nm, 54nm, 56nm, 58nm, 60nm, 64nm, 68nm, 72nm, 80nm, 92nm, 100nm and 120nm.
In the embodiment of the disclosure, the preset design value includes a plurality of values, so that the process capability range of the photomask factory can be more comprehensively tested, and the target pattern can be accurately compensated.
In some embodiments, referring to fig. 3 or fig. 4, the first test pattern set 11 includes a plurality of first test pattern groups 13, where each first test pattern group 13 corresponds to one of the preset design values in the preset design value set, for example, the preset design value corresponding to the first test pattern group 13 from the left in the first row is 40nm, the preset design value corresponding to the second first test pattern group 13 from the left in the first row is 42nm, and the preset design value corresponding to the third first test pattern group 13 from the left in the first row is 44nm. The design value of the critical dimension of each first test pattern 101 in the same first test pattern group 13 in the horizontal direction is the same as the preset design value corresponding to the first test pattern group 13. For example, the preset design value corresponding to the first test pattern group 13 from the left in the first row is 40nm, and then the design value of the critical dimension of all the first test patterns 101 in the first test pattern group 13 in the horizontal direction is 40nm.
With continued reference to fig. 3 or fig. 4, the second test pattern set 12 includes a plurality of second test pattern groups 14, each second test pattern group 14 corresponds to one preset design value in the preset design value set, and the design value of the critical dimension of each second test pattern 102 in the same second test pattern group 14 in the vertical direction is the same as the preset design value corresponding to the second test pattern group 14.
It should be noted that, for convenience, the preset design values corresponding to the plurality of first test pattern groups shown in fig. 3 and 4 are the same, and the preset design values corresponding to the plurality of second test pattern groups are the same, but in implementation, the preset design values corresponding to the plurality of first test pattern groups should be different, and the preset design values corresponding to the plurality of second test pattern groups should be different.
In implementation, the number of the first test pattern groups in the first test pattern set may be determined according to the number of preset design values in the preset design value set. For example, the number of preset design values is 18, and the number of the first test pattern groups may be 18; in other embodiments, the first test pattern group may be another number.
The 18 first test pattern groups may be arranged in a matrix manner as shown in fig. 3 or fig. 4, and each of the first, second, …, and sixth rows includes 3 first test pattern groups 13. In some embodiments, the 18 first test pattern groups may be arranged in three rows of 6 first test pattern groups each. In other embodiments, the plurality of first test pattern groups may not be arranged in a matrix manner.
In some embodiments, the implementation of "determining the target graphic set of the corresponding exposure area in the first design data file based on the first comparison result" may include step S1031 and step S1032, wherein:
step S1031, determining a target design value based on the first comparison result;
the target design value is a design value of a critical dimension of a target test pattern in the test pattern set, and the measurement value of the critical dimension of the target test pattern is smaller than the design value of the critical dimension;
here, the test pattern set is located in a non-exposed area in the current photomask; the target design values may be one, two or even more, and in implementation, the design values of the critical dimension of the test pattern may be randomly sampled in the union of the design values of the critical dimension of the test pattern to obtain the design value of the critical dimension of the test pattern to check whether the photomask factory can prepare the pattern of the critical dimension, for example, the design values of the critical dimension of the test pattern which is randomly extracted are 52nm and 48nm, if the design value of the critical dimension is 52nm, the measurement value of the critical dimension of the test pattern which is 52nm is measured, the first comparison result is 0, which indicates that the photomask factory can accurately prepare the pattern of the critical dimension; if the critical dimension measurement value of the test pattern with the critical dimension design value of 48nm is 46nm, and the first comparison result is-2, the mask factory can not accurately prepare the critical dimension pattern, and then the 46nm is determined as the target design value.
Step S1032, determining the union of sub-resolution auxiliary graphics meeting the first preset condition in the first design data file as a target graphics set;
the first preset condition includes that the design value of the key size is smaller than the target design value and is located in the first design data file corresponding to the exposure area.
Here, step S1032 is a process of screening out sub-resolution auxiliary patterns which are located in the corresponding exposure area and have a design value of the critical dimension smaller than the target design value in the first design data file.
In the embodiment of the disclosure, the target design value is determined based on the first comparison result, and then the union of the sub-resolution auxiliary graphs which are located in the first design data file and correspond to the exposure area and have the critical dimension smaller than the target design value is determined as the target graph set, so that the adjustment of the critical dimension design value of all the sub-resolution auxiliary graphs in the target graph set can be conveniently performed at one time later, and the time can be saved.
In some embodiments, the target design value includes a first target design value, and step S1031 may be implemented by step S131a, wherein:
step S131a, determining a first target design value based on the first comparison result;
The first target design value is a preset design value corresponding to a target first test pattern group in the first test pattern set, and the measured value of the critical dimension of the target first test pattern group is smaller than the preset design value corresponding to the target first test pattern group;
correspondingly, step S1032 may be implemented by step S132a, wherein:
step S132a, determining a union set of sub-resolution auxiliary graphs meeting a first sub-preset condition in a first design data file as a target graph set;
the first sub-preset condition includes that a design value of a critical dimension, which is located in the first design data file and corresponds to the exposure area, extends in the vertical direction and is smaller than a first target design value.
Here, the first target design value may be a design value of one critical dimension in the preset design value set, for example, may be 52nm.
In the embodiment of the disclosure, based on the first comparison result, a first target design value is determined, and a union set of sub-resolution auxiliary patterns meeting a first sub-preset condition in the first design data file is determined as a target pattern set, so that all sub-resolution auxiliary patterns which are located in an exposure area and extend in a vertical direction in the first design data file and have a critical dimension design value smaller than the first target design value can be screened out.
In some embodiments, the target design value comprises a second target design value; step S1031 may be implemented by step S131b, wherein:
step S131b, determining a second target design value based on the first comparison result;
the second target design value is a preset design value corresponding to a target second test pattern group in the second test pattern set, and the measured value of the critical dimension of the target second test pattern group is smaller than the preset design value corresponding to the target second test pattern group;
correspondingly, step S1032 may be implemented by step S132b, wherein:
step S132b, determining the union of sub-resolution auxiliary graphs meeting the second sub-preset condition in the first design data file as a target graph set; the second sub-preset condition includes that the design value of the key size, which is located in the first design data file and corresponds to the exposure area, extends along the horizontal direction and is smaller than the second target design value.
Here, the second target design value may be the same as the first target design value, and the second target design value may also be different from the first target design value. The second target design value may be a design value of one critical dimension in the set of preset design values.
In the embodiment of the disclosure, based on the first comparison result, the second target design value is determined, and the union set of the sub-resolution auxiliary patterns satisfying the second sub-preset condition in the first design data file is determined as the target pattern set, so that all the sub-resolution auxiliary patterns which are located in the exposure area and extend in the horizontal direction and have the critical dimension design value smaller than the second target design value in the first design data file can be screened out.
In some embodiments, step S131a and step S131b may be performed simultaneously, and then step S132a and step S132b may be performed simultaneously, so that sub-resolution auxiliary graphs satisfying the first sub-preset condition and satisfying the second sub-preset condition in the first design data file may be screened out simultaneously.
In some embodiments, referring to fig. 5, each first test pattern group 13 includes N first test pattern subsets (fig. 5 shows 4 first test pattern subsets, namely, a 1 st first test pattern subset 131, a 2 nd first test pattern subset 132, a 3 rd first test pattern subset 133, and a 4 th first test pattern subset 134), where the nth first test pattern subset includes one first test pattern, the ith first test pattern subset includes at least one first test pattern uniformly arranged along a horizontal direction, a space between the first test patterns in the ith first test pattern subset is smaller than a space between the first test patterns in the (i+1) th first test pattern subset, N is a positive integer greater than 1, and i is a positive integer less than N-1. As can be seen from fig. 5: the 1 st first test pattern subset 131 includes 19 first test patterns 101 uniformly arranged in the horizontal direction, i.e., sequentially arranged at equal intervals; the 2 nd first test pattern subset 132 includes 9 first test patterns 101 uniformly arranged in the horizontal direction; the 3 rd first test pattern subset 133 includes 3 first test patterns 101 uniformly arranged in the horizontal direction; the 4 th first test pattern subset 134 includes 1 first test pattern 101.
In some embodiments, each first test pattern has a dimension in the vertical direction ranging from 5 micrometers (μm) to 15 μm. For example, with continued reference to fig. 5, each first test pattern 101 may have a dimension in the vertical direction of 10 μm; if the dimensions in the vertical direction of each first test pattern 101 in the 1 st to 4 th first test pattern subsets are denoted as A1, B1, C1, and D1, respectively, a1=b1=c1=d1=10μm.
The dimension of each second test pattern 102 in the horizontal direction ranges from 5 μm to 15 μm. For example, referring to fig. 7, the size of each of the second test patterns 102 in the horizontal direction may be 10 μm, and if the sizes of the second test patterns 102 in the 1 st to 4 th second test pattern subsets in the horizontal direction are denoted as A2, B2, C2, and D2, respectively, a2=b2=c2=d2=10μm.
It should be noted that the number of the first test pattern subsets in the different first test pattern groups may be the same or different. In addition, N first test pattern subsets in the first test pattern group may be arranged along a vertical direction, and under the condition that N first test pattern subsets are arranged along the vertical direction, the first test patterns in the adjacent two first test pattern subsets may be arranged in a staggered manner and not connected, and the first test patterns in the adjacent two first test pattern subsets may also be connected. The N first test pattern subsets in the first test pattern group may also be sequentially arranged in the horizontal direction, which is not limited by the embodiment of the present disclosure.
As can be seen from fig. 5, the 1 st, 2 nd, 3 rd, and 4 th first test pattern subsets 131, 132, 133, and 134 are arranged in a vertical direction, and in other embodiments, referring to fig. 6, the 1 st, 2 nd, 3 rd, 133, and 4 th first test pattern subsets 134 may also be arranged in a horizontal direction.
The interval between two adjacent first test patterns in each first test pattern subset can be any value, and in implementation, only the interval between the first test patterns in the ith first test pattern subset is required to be smaller than the interval between the first test patterns in the (i+1) th first test pattern subset, so that the densities of the first test patterns in the first test pattern subset are sequentially reduced. Thus, the first subset of test patterns in the first test pattern group may include 4 types of isolated patterns, isolation-like patterns, semi-isolated patterns, and dense patterns; the density of the isolated pattern is minimum, the density of the dense pattern is maximum, and the densities of the similar isolated pattern and the semi-isolated pattern are between those of the isolated pattern and the dense pattern.
In the embodiment of the disclosure, the densities of the first test pattern subsets in the first test pattern group and the densities of the second test pattern subsets in the second test pattern group are different, so that when the test patterns with the design values of the same critical dimension are found to have differences between the measured values of the critical dimension and the design values of the critical dimension only in a certain density area, only the design values of the critical dimension at the corresponding density position need to be adjusted when the design values of the critical dimension of the target pattern are adjusted, thereby reducing the adjustment workload and enabling the adjustment to be more accurate.
Referring to fig. 7, each of the second test pattern groups 14 includes M second test pattern subsets (fig. 7 shows 4 second test pattern subsets, namely, a 1 st second test pattern subset 141, a 2 nd second test pattern subset 142, a 3 rd second test pattern subset 143, and a 4 th second test pattern subset 144), wherein the M second test pattern subset includes one second test pattern, the j second test pattern subset includes at least one second test pattern uniformly arranged along a vertical direction, a space between the second test patterns in the j second test pattern subset is smaller than a space between the second test patterns in the j+1th second test pattern subset, M is a positive integer, and j is a positive integer smaller than M-1.
It should be noted that the number of the second test pattern subsets in the different second test pattern groups may be the same or different. In addition, M second test pattern subsets in the second test pattern group may be arranged in a horizontal direction, and in the case that the M second test pattern subsets are arranged in the horizontal direction, the second test patterns in the adjacent two second test pattern subsets may be arranged in a staggered manner and not connected; the second test patterns of the adjacent two second test pattern subsets may also be connected. The M second test pattern subsets in the second test pattern group may also be sequentially arranged in the vertical direction, which is not limited by the embodiment of the present disclosure.
In some embodiments, the spacing S between adjacent ones of the (i+1) th first test patterns in the subset of first test patterns i+1 ＝((1+p) i -1)×CD k +(1+p) i ×S 1 The method comprises the steps of carrying out a first treatment on the surface of the Spacing L between adjacent two second test patterns in the j+1th second test pattern subset j+1 ＝((1+q) j -1)×CD m ＇+(1+q) j ×L 1 。
Wherein, CD k A design value for the critical dimension of the first test pattern in the kth first test pattern group; CD (compact disc) m ' is the design value of the critical dimension of the second test pattern in the mth second test pattern group; p is a positive integer not exceeding (R-3)/2, R is the total number of first test patterns in the 1 st first test pattern subset; q is a positive integer not exceeding (T-3)/2, T is the total number of second test patterns in the 1 st second test pattern subset, and R and T are integers greater than or equal to 5; s is S 1 A spacing between two adjacent first test patterns in the 1 st first test pattern subset; l (L) 1 Is the spacing between two adjacent second test patterns in the 1 st subset of second test patterns.
Referring to fig. 8, the first test pattern group 13 includes a 1 st first test pattern subset 131, a 2 nd first test pattern subset 132, a 3 rd first test pattern subset 133, a 4 th first test pattern subset 134, and a 5 th first test pattern subset 135. For the first test pattern group 13, in the case of i=1, p=1, the interval between two adjacent first test patterns 101 in the 2 nd first test pattern subset 132S 2 ＝((1+1) 1 -1)×CD 1 +(1+1) 1 ×S 1 ＝CD 1 +2S 1 The method comprises the steps of carrying out a first treatment on the surface of the In the case of i=2, the interval S between two adjacent first test patterns 101 in the 3 rd first test pattern subset 133 3 ＝((1+1) 2 -1)×CD 1 +(1+1) 2 ×S 1 ＝3CD 1 +4S 1 The method comprises the steps of carrying out a first treatment on the surface of the Spacing S between adjacent two first test patterns 101 in the 4 th first test pattern subset 134 4 ＝((1+1) 3 -1)×CD 1 +(1+1) 3 ×S 1 ＝7CD 1 +8S 1 。
Referring to fig. 5, for the first test pattern group 13, the interval S between adjacent two first test patterns 101 in the 2 nd first test pattern subset 132 2 ＝CD 1 +2S 1 The method comprises the steps of carrying out a first treatment on the surface of the Spacing S between adjacent two first test patterns 101 in the 3 rd first test pattern subset 133 3 ＝5CD 1 +6S 1 。
Referring to fig. 9, the second test pattern group 14 includes a 1 st second test pattern subset 141, a 2 nd second test pattern subset 142, a 3 rd second test pattern subset 143, a 4 th second test pattern subset 144, and a 5 th second test pattern subset 145. For the first second test pattern group 14, in the case of j=1, q=1, the interval L between two adjacent second test patterns 102 in the 2 nd second test pattern subset 142 2 ＝((1+1) 1 -1)×CD 1 ＇+(1+1) 1 ×L 1 ＝CD 1 ＇+2L 1 The method comprises the steps of carrying out a first treatment on the surface of the In the case where j=2, the interval L between two adjacent second test patterns 102 in the 3 rd second test pattern subset 143 3 ＝((1+1) 2 -1)×CD 1 ＇+(1+1) 2 ×L 1 ＝3CD 1 ＇+4L 1 The method comprises the steps of carrying out a first treatment on the surface of the The spacing L between two adjacent second test patterns 102 in the 4 th second test pattern subset 144 4 ＝((1+1) 3 -1)×CD 1 ＇+(1+1) 3 ×L 1 ＝7CD 1 ＇+8L 1 。
Referring to fig. 7, for a first second test pattern group 14, two adjacent test pattern subsets 142 in a second test pattern subset 2Spacing L between second test patterns 102 2 ＝CD 1 ＇+2L 1 The method comprises the steps of carrying out a first treatment on the surface of the Spacing L between adjacent second test patterns 102 in 3 rd second test pattern subset 142 3 ＝5CD 1 ＇+6L 1 。
In some embodiments, the N first test pattern subsets are arranged sequentially in a vertical direction; each first test pattern in the (i+1) th first test pattern subset is respectively connected with each first test pattern of p first test patterns in the (i) th first test pattern subset in sequence at intervals.
In some embodiments, referring to fig. 8, each first test pattern 101 in the 2 nd first test pattern subset 132 is connected to each first test pattern of the 1 st first test pattern subset 131 sequentially spaced 1 first test pattern 101 one by one. Each first test pattern 101 in the 3 rd first test pattern subset 133 is connected to each first test pattern of the 2 nd first test pattern subset 132, which is sequentially separated by 1 first test pattern 101. Each first test pattern 101 in the 4 th first test pattern subset 134 is connected to each first test pattern of the 3 rd first test pattern subset 133, which is sequentially separated by 1 first test pattern 101.
In other embodiments, p may take other values, e.g., 2, 3, etc. Each first test pattern in the (i+1) th first test pattern subset is respectively connected with each first test pattern of the (i) th first test pattern subset at intervals of 1 first test pattern in sequence one by one; each first test pattern in the (i+2) th first test pattern subset is respectively connected with each first test pattern in the (i+1) th first test pattern subset, which is sequentially separated by 2 first test patterns, each first test pattern in the (i+3) th first test pattern subset is respectively connected with each first test pattern in the (i+2) th first test pattern subset, which is sequentially separated by 3 first test patterns, and so on.
The M second test pattern subsets are sequentially arranged along the horizontal direction; each second test pattern in the j+1th second test pattern subset is respectively connected with each second test pattern of the q second test patterns in the j second test pattern subset at intervals in sequence.
Referring to fig. 9, each second test pattern 102 in the 2 nd second test pattern subset 142 is connected to each second test pattern of the 1 st second test pattern subset 141, respectively, with a 1 st second test pattern 102 in sequence.
It should be noted that, the second test pattern set may be understood by referring to the first test pattern set, and the difference between the two test pattern sets is at least: the extending directions of the first test patterns in the first test pattern set and the extending directions of the second test patterns in the second test pattern set are different.
In some embodiments, comparing the measured value of the critical dimension of each test pattern with the design value of the critical dimension to obtain the first comparison result may include:
comparing the measured value of the key size of each first test pattern in each first test pattern group with the corresponding preset design value of the first test pattern group to obtain a first sub-comparison result;
comparing the measured value of the key size of each second test pattern in each second test pattern group with the corresponding preset design value of the second test pattern group to obtain a second sub-comparison result;
the first comparison result is determined based on the first sub-comparison result and the second sub-comparison result.
In some embodiments, the implementation of step S1032 "determine the union of sub-resolution auxiliary graphics satisfying the first preset condition in the first design data file as the target graphic set" may include:
step S1321, the extending direction of the test pattern corresponding to the target design value and the interval between two adjacent test patterns with the target design value are respectively used as the target extending direction and the target interval;
Here, the target extending direction may be a horizontal direction or a vertical direction, and the sub-resolution auxiliary pattern identical to the extending direction of the first test pattern or the second test pattern may be selected by using the target extending direction as one of the third sub-preset conditions. When the target extending direction is the horizontal direction, the target interval may beIs the spacing L between two adjacent second test patterns in the j-th second test pattern subset j The interval between adjacent sub-resolution auxiliary patterns can be screened out to be L by adopting the target interval as one condition in the third sub-preset condition j Sub-resolution auxiliary pattern of (c).
Step S1322, determining the union of the sub-resolution auxiliary graphs of which the first design data file meets the third sub-preset condition as a target graph set; the third sub-preset condition includes that a design value of a critical dimension corresponding to an exposure area in the first design data file is smaller than a target design value, an interval between two adjacent first test patterns or second test patterns is a target interval, and an extending direction is a target extending direction.
In the embodiment of the disclosure, the extending direction of the test pattern corresponding to the target design value and the interval between two adjacent test patterns with the target design value are respectively used as the target extending direction and the target interval, and the union of the sub-resolution auxiliary patterns of the first design data file meeting the third sub-preset condition is determined as the target pattern set, so that all the sub-resolution auxiliary patterns which are positioned in the first design data file and correspond to the exposure area and have the target interval (i.e. have the target density) and the target extending direction and have the critical dimension design value smaller than the target design value can be screened out, the sub-resolution auxiliary patterns to be regulated can be accurately screened out by setting the screening condition, and the subsequent regulation of the design values of the critical dimension of all the screened sub-resolution auxiliary patterns is facilitated.
In some embodiments, step S104 "update the first design data file based on the adjustment value corresponding to the design value of the critical dimension of each target graphic to obtain the second design data file" may be implemented in steps S1041 and S1042, where:
step S1041, adjusting the coordinate information of each target graph based on the adjustment value corresponding to the design value of the critical dimension of each target graph to obtain the adjusted coordinate information of each target graph;
here, if the target pattern is rectangular, the coordinates of four points of the rectangle before adjustment are (X3, Y3), (X4, Y4) and (X3, Y4) in order, and if the adjustment value corresponding to the design value of the critical dimension of the target pattern in the horizontal direction is 2X, both the abscissa X3 and X4 can be adjusted, and the coordinates after adjustment of the target pattern can be (X3-X, Y3), (x4+x, Y4) and (X3-X, Y4) in order, so that the center of the pattern can be kept unchanged; it is also possible to adjust only one abscissa, for example X3, and the coordinates of the target pattern after adjustment may be (X3-2X, Y3), (X4, Y4), and (X3-2X, Y4) in this order.
In step S1042, the first design data file is updated based on the coordinate information of each target graphic after adjustment to obtain a second design data file.
In some embodiments, the implementation of step S1041 may include: for the target graphics extending in the vertical direction in the target graphics set, adjusting the abscissa in the coordinate information of each target graphics based on the adjustment value corresponding to the design value of the key size of each target graphics to obtain the adjusted coordinate information of each target graphics; and/or, for the target graphics extending along the horizontal direction in the target graphics set, adjusting the ordinate in the coordinate information of each target graphics based on the adjustment value corresponding to the design value of the critical dimension of each target graphics, so as to obtain the adjusted coordinate information of each target graphics. In other embodiments, an abscissa or an ordinate of each target graphic may also be adjusted.
In some embodiments, the implementation of step S1042 may include steps S141 to S143, wherein:
step S141, dividing the first design data file into a first design data subfile and a second design data subfile; wherein the first design data subfile includes a target graphic set and the second design data subfile includes graphics other than the target graphic set in the graphic aggregate set in the first design data file;
Step S142, updating the first design data subfile based on the coordinate information of each target graph after adjustment to obtain a third design data subfile;
step S143, obtaining the second design data file based on the third design data subfile and the second design data subfile.
In the embodiment of the disclosure, in the process of compensating the design values of the critical dimensions of the target graphics in the target graphics set, the first design data file is divided into the first design data subfile and the second design data subfile, and only the design values of the critical dimensions of the target graphics in the first design data subfile are adjusted, but not all the graphics in the first design data file are compensated, so that the influence on the graphics data in the second design data subfile can be reduced.
In some embodiments, the method of preparing a photomask further comprises steps S106 to S108, wherein:
step S106, comparing the measurement value of the critical dimension of the sub-resolution auxiliary graph in the target photomask with the design value of the critical dimension to determine a second comparison result;
step S107, obtaining the defect detection result of the target photomask;
step S108, when the second comparison result meets the preset threshold value and the defect detection result of the target photomask is that the defect does not exist, determining that the target photomask is a qualified photomask.
Here, steps S106 to S108 may be acceptance of the target mask. The critical dimension measurement values of the sub-resolution assist feature in the target mask may be measured by scanning electron microscopy for critical dimension measurement. The second comparison result may be used to reflect the effect of the design value adjustment on the sub-resolution auxiliary pattern critical dimension in the first design data file. If the second comparison result meets the preset threshold value, the effect of adjusting the design value of the sub-resolution auxiliary graph key size in the first design data file is better; wherein the predetermined threshold may be an acceptable error value.
The defect detection device of the photomask, such as an intelligent photomask detection machine (Intelligent Reticle Inspection Station, IRIS), may be used to detect the defects of the photomask, and a contrast mode of die to die (a defect scanning method using a unit chip as a contrast unit) or a contrast mode of shot to shot (a defect scanning method using a region defined by the photomask as a contrast unit) may be used to determine whether the defects exist on the photomask.
In some embodiments, it may also be detected whether the process window of the mask satisfies a preset condition.
In some embodiments, if the target mask is a defective mask, steps S101 to S105 may be continued to be performed to adjust or compensate the design value of the critical dimension of the sub-resolution pattern in the target mask until a qualified mask is obtained.
The method of preparing a photomask provided by the present disclosure will be further described by way of an example.
Firstly, transferring the patterns in the test pattern set to available space in a non-exposure area of a current photomask; then, the desired measurement points (which may include the target mask pattern, sub-resolution assist pattern and test pattern in the mask) are selected to form a CD measurement file, and the CD measurement file is submitted to the mask factory for measurement, so as to obtain the data in Table 1.
TABLE 1 design values of critical dimensions and measurement values of critical dimensions for each measurement point
Measuring point Design value of critical dimension Measurement of critical dimensions ΔCD
Cell CD1 270 269 1
Cell CD2 264 264 0
SRAF_C CD1 52 46 -6
M_SRAF_C CD-60 60 58 -2
M_SRAF_C-A CD-52 52 46 -6
M_SRAF_C-B CD-48 48 41 -7
M_SRAF_D-A CD-52 52 54 2
M_SRAF_D-B CD-48 48 51 3
Here, cell CD1 represents the target mask pattern 103 in fig. 10, and Cell CD2 represents another target mask pattern. Sraf_ccd1 represents the sub-resolution assist feature 104 in the bright field mask of fig. 10; M_SRAF_CCD-60 represents a test pattern with a design value of 60nm for critical dimensions in a bright field mask; M_SRAF_C-A CD-52 can represent the 1 st second subset of test patterns (or the first subset of test patterns) with se:Sub>A design value of 52nm for critical dimensions in the bright field mask; M_SRAF_C-A CD-48 may represent the 2 nd second subset of test patterns with se:Sub>A design value of 48nm for critical dimensions in the bright field mask; M_SRAF_D-A CD-52 can represent the 1 st second subset of test patterns with a design value of 52nm for critical dimensions in a dark field mask; M_SRAF_D-A CD-48 may represent the 2 nd second subset of test patterns with a design value of 48nm for critical dimensions in the dark field mask; ΔCD is the difference between the design value of the critical dimension of the pattern and the measured value of the critical dimension.
As can be seen from table 1: the absolute value of the delta CD of the test pattern with the design value of the critical dimension less than or equal to 52nm is larger, so that the sub-resolution auxiliary pattern with the design value of the critical dimension less than or equal to 52nm can be determined to be influenced by the process difference of the photomask plant. The adjustment value of the sub-resolution auxiliary pattern may be determined to be +4 based on Δcd and experience.
Thereafter, with continued reference to fig. 10, mask Rule Check (MRC) rules or OPC may be used to assign the sub-resolution auxiliary pattern 105 with a critical dimension having a design value less than 52nm to a separate design data file (corresponding to the first design data subfile in the foregoing embodiment), and +2 may be added to the upper and lower sides of the sub-resolution auxiliary pattern 105 with a critical dimension having a design value less than 52nm (as shown in fig. 11) or +2 may be added to the upper and lower sides, respectively. Thus, an updated design data file (corresponding to the third design data subfile in the foregoing embodiment) may be formed, so that a second design data file may be obtained, and then, the target photomask may be prepared based on the second design data file. Finally, the target photomask is inspected. Fig. 12 is a) and c) are schematic diagrams of defect cases in the target mask in the related art and the embodiments of the present disclosure, respectively, and b) and d) are schematic diagrams of sub-resolution assist patterns in the target mask in the related art and the embodiments of the present disclosure, respectively. Comparing the a) and b) of fig. 12, it can be seen that: the defects in the target mask in the related art are more (white points represent defective places), while the defects in the target mask in the embodiments of the present disclosure are less; comparing fig. 12, c) with d) shows that: c) A broken defect occurs in the dashed box 301 in the figure, and d) a broken defect does not occur in the dashed box 302 in the figure.
Embodiments of the present disclosure also provide a photomask manufactured by the method for manufacturing a photomask according to any of the embodiments described above, and referring to fig. 2, the photomask (which may be the current photomask 20 or the target photomask) has an exposed area 22 and a non-exposed area 21, wherein the exposed area 22 includes a target photomask pattern 202 and at least one sub-resolution auxiliary pattern 201, and the non-exposed area 21 includes a test pattern set 10.
In several embodiments provided by the present disclosure, it should be understood that the disclosed apparatus and methods may be implemented in a non-targeted manner. The above described device embodiments are only illustrative, e.g. the division of the units is only one logical function division, and there may be other divisions in practice, such as: multiple units or components may be combined or may be integrated into another system, or some features may be omitted, or not performed. In addition, the components shown or discussed are coupled to each other or directly.
The units described as separate units may or may not be physically separate, and units displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units; some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
The features disclosed in the several method or apparatus embodiments provided in the present disclosure may be arbitrarily combined without any conflict to obtain new method embodiments or apparatus embodiments.
While the foregoing is directed to embodiments of the present disclosure, the scope of the embodiments of the present disclosure is not limited to the foregoing, and any changes and substitutions that are within the scope of the embodiments of the present disclosure will be readily apparent to those skilled in the art. Therefore, the protection scope of the embodiments of the present disclosure shall be subject to the protection scope of the claims.

Claims (18)

1. A method of making a photomask, the method comprising:
acquiring a measurement value of a critical dimension and a design value of the critical dimension of each test pattern in a test pattern set positioned in a non-exposure area of a current photomask; the current photomask is prepared based on a first design data file;
comparing the measured value of the critical dimension of each test pattern with the design value of the critical dimension to obtain a first comparison result;
determining a target graph set corresponding to an exposure area in the first design data file and an adjustment value corresponding to a design value of a critical dimension of each target graph in the target graph set based on the first comparison result;
Updating the first design data file based on the adjustment value corresponding to the design value of the critical dimension of each target graph to obtain a second design data file;
and preparing the target photomask based on the second design data file.
2. The method of claim 1, wherein the determining the target graphic set for the corresponding exposure area in the first design data file based on the first comparison result comprises:
determining a target design value based on the first comparison result; the target design value is a design value of a critical dimension of a target test pattern in the test pattern set, and the measurement value of the critical dimension of the target test pattern is smaller than the design value of the critical dimension;
determining a union set of sub-resolution auxiliary graphs meeting a first preset condition in the first design data file as the target graph set; the first preset condition includes that a design value of a critical dimension of the first design data file corresponding to an exposure area is smaller than the target design value.
3. The method of claim 2, wherein the set of test patterns comprises a first set of test patterns and a second set of test patterns; the first test pattern set comprises a plurality of first test patterns extending along the vertical direction, and the design value of the critical dimension of each first test pattern in the horizontal direction is the same as one preset design value in a preset design value set; the second test pattern set comprises a plurality of second test patterns extending along the horizontal direction, and the design value of the critical dimension of each second test pattern in the vertical direction is the same as one preset design value in the preset design value set.
4. The method of claim 3, wherein the first set of test patterns includes a plurality of first test pattern groups, each of the first test pattern groups corresponds to one of the predetermined design values in the set of predetermined design values, and the design value of the critical dimension of each of the first test patterns in the same first test pattern group in the horizontal direction is the same as the predetermined design value corresponding to the first test pattern group;
the second test pattern set comprises a plurality of second test pattern groups, each second test pattern group corresponds to one preset design value in the preset design value set, and the design value of the critical dimension of each second test pattern in the same second test pattern group in the vertical direction is the same as the preset design value corresponding to the second test pattern group.
5. The method of claim 4, wherein the target design value comprises a first target design value;
determining a target design value based on the first comparison result, including:
determining a first target design value based on the first comparison result; the first target design value is a preset design value corresponding to a target first test pattern group in the first test pattern set, and the measurement value of the critical dimension of the target first test pattern group is smaller than the preset design value corresponding to the target first test pattern group;
Determining the union of sub-resolution auxiliary graphs meeting a first preset condition in the first design data file as the target graph set, wherein the method comprises the following steps:
determining a union set of sub-resolution auxiliary graphs meeting a first sub-preset condition in the first design data file as the target graph set; the first sub-preset condition includes that a design value of a critical dimension extending in a vertical direction in the first design data file corresponding to an exposure area is smaller than the first target design value.
6. The method of claim 4, wherein the target design value comprises a second target design value;
determining a target design value based on the first comparison result, including:
determining a second target design value based on the first comparison result; the second target design value is a preset design value corresponding to a target second test pattern group in the second test pattern set, and the measurement value of the critical dimension of the target second test pattern group is smaller than the preset design value corresponding to the target second test pattern group;
determining the union of sub-resolution auxiliary graphs meeting a first preset condition in the first design data file as the target graph set, wherein the method comprises the following steps:
Determining a union set of sub-resolution auxiliary graphs meeting a second sub-preset condition in the first design data file as the target graph set; the second sub-preset condition includes that a design value of a critical dimension extending in a horizontal direction in the first design data file corresponding to the exposure area is smaller than the second target design value.
7. The method of any one of claims 3 to 6, wherein each of the first test patterns has a dimension in the vertical direction in the range of 5 micrometers to 15 micrometers; each of the second test patterns has a dimension in the horizontal direction ranging from 5 micrometers to 15 micrometers.
8. The method according to any one of claims 3 to 6, wherein in the case where the current mask is a bright field mask, the first test pattern and the second test pattern each comprise a line pattern;
in the case where the current mask is a dark field mask, the first test pattern and the second test pattern each include a void pattern.
9. The method according to any one of claims 3 to 6, wherein the set of preset design values comprises at least one of the following preset design values: 40 nm, 42 nm, 44 nm, 46 nm, 48 nm, 50 nm, 52 nm, 54 nm, 56 nm, 58 nm, 60 nm, 64 nm, 68 nm, 72 nm, 80 nm, 92 nm, 100 nm and 120 nm.
10. The method according to any one of claims 4 to 6, wherein each of the first test pattern groups includes N first test pattern subsets, wherein an nth first test pattern subset includes one first test pattern, an ith first test pattern subset includes at least one first test pattern uniformly arranged in a horizontal direction, a spacing between the first test patterns in the ith first test pattern subset is smaller than a spacing between the first test patterns in the (i+1) th first test pattern subset, N is a positive integer greater than 1, and i is a positive integer less than N-1;
each second test pattern group comprises M second test pattern subsets, wherein the M second test pattern subsets comprise one second test pattern, the j second test pattern subsets comprise at least one second test pattern uniformly distributed along the vertical direction, the interval between the second test patterns in the j second test pattern subsets is smaller than the interval between the second test patterns in the j+1th second test pattern subsets, M is a positive integer larger than 1, and j is a positive integer smaller than M-1.
11. The method of claim 10, wherein a spacing S between two adjacent first test patterns in the i+1th subset of first test patterns i+1 ＝((1+p) i -1)×CD k +(1+p) i ×S 1 The method comprises the steps of carrying out a first treatment on the surface of the The interval L between two adjacent second test patterns in the j+1th second test pattern subset j+1 ＝((1+q) j -1)×CD m ＇+(1+q) j ×L 1 ；
Wherein, CD k A design value for the critical dimension of the first test pattern in the kth first test pattern group; CD (compact disc) m ' is the design value of the critical dimension of the second test pattern in the mth second test pattern group; p is a positive integer not exceeding (R-3)/2, R is the total number of first test patterns in the 1 st first test pattern subset; q is a positive integer not exceeding (T-3)/2, T is the total number of second test patterns in the 1 st second test pattern subset, and R and T are integers greater than or equal to 5; the S is 1 A spacing between two adjacent first test patterns in the 1 st first test pattern subset; the L is 1 Is the spacing between two adjacent second test patterns in the 1 st subset of second test patterns.
12. The method of claim 11, wherein the N first test pattern subsets are arranged sequentially in a vertical direction; each first test pattern in the (i+1) th first test pattern subset is respectively connected with each first test pattern of p first test patterns in the (i) th first test pattern subset in sequence at intervals one by one;
the M second test pattern subsets are sequentially arranged along the horizontal direction; each second test pattern in the j+1th second test pattern subset is respectively connected with each second test pattern of the q second test patterns in the j second test subset in sequence at intervals.
13. The method of claim 10, wherein determining the union of sub-resolution auxiliary graphics in the first design data file that satisfy a first preset condition as the target graphics set comprises:
taking the extending direction of the test pattern corresponding to the target design value and the interval between two adjacent test patterns with the target design value as a target extending direction and a target interval respectively;
determining a union of sub-resolution auxiliary graphs of which the first design data file meets a third sub-preset condition as the target graph set; the third sub-preset condition includes that a design value of a critical dimension corresponding to an exposure area in the first design data file is smaller than the target design value, an interval between two adjacent sub-resolution auxiliary patterns is the target interval, and an extending direction is the target extending direction.
14. The method according to any one of claims 1 to 6, wherein updating the first design data file based on the adjustment value corresponding to the design value of the critical dimension of each target graphic to obtain a second design data file includes:
Adjusting the coordinate information of each target graph based on an adjustment value corresponding to a design value of the critical dimension of each target graph to obtain the adjusted coordinate information of each target graph;
and updating the first design data file based on the coordinate information of each target graph after adjustment to obtain the second design data file.
15. The method of claim 14, wherein updating the first design data file based on the adjusted coordinate information for each of the target graphics to obtain the second design data file comprises:
dividing the first design data file into a first design data subfile and a second design data subfile; wherein the first design data subfile includes the target set of graphics and the second design data subfile includes graphics other than the target set of graphics in the total set of graphics in the first design data file;
updating the first design data subfile based on the coordinate information of each target graph after adjustment to obtain a third design data subfile;
and obtaining the second design data file based on the third design data subfile and the second design data subfile.
16. The method of claim 15, wherein adjusting the coordinate information of each target pattern based on the adjustment value corresponding to the design value of the critical dimension of each target pattern to obtain the adjusted coordinate information of each target pattern comprises: for the target graphics extending in the vertical direction in the target graphics set, adjusting the abscissa in the coordinate information of each target graphics based on the adjustment value corresponding to the design value of the key size of each target graphics to obtain the coordinate information of each target graphics after adjustment;
and/or, for the target graphics extending along the horizontal direction in the target graphics set, adjusting the ordinate in the coordinate information of each target graphics based on the adjustment value corresponding to the design value of the critical dimension of each target graphics, so as to obtain the adjusted coordinate information of each target graphics.
17. The method according to any one of claims 1 to 6, further comprising:
comparing the measured value of the critical dimension of the sub-resolution auxiliary graph in the target photomask with the design value of the critical dimension to determine a second comparison result;
Obtaining a defect detection result of the target photomask;
and determining that the target photomask is a qualified photomask under the condition that the second comparison result meets a preset threshold value and the defect detection result of the target photomask is that no defect exists.
18. A photomask produced by the method of producing a photomask according to claims 1 to 17, said photomask having an exposed area and a non-exposed area, said exposed area comprising a target photomask pattern and at least one sub-resolution assist pattern, said non-exposed area comprising a test pattern set.
CN202211185327.1A 2022-09-27 2022-09-27 Photomask and method for manufacturing the same Pending CN117826523A (en)

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