Photoetching mask, alignment mark and same-layer exposure error compensation method

Abstract

The embodiment of the invention relates to a photoetching mask, a photoetching alignment mark and a same-layer exposure error compensation method, and the photoetching mask comprises an exposure unit which is used for carrying out stepping exposure on a wafer and comprises at least one group of photoetching alignment patterns consisting of a first pattern and a second pattern, the first pattern and the second pattern are respectively positioned on two sides, far away from each other, of the exposure unit along the stepping direction, and the first pattern and the second pattern are open patterns; a first mark and a second mark are correspondingly formed when the first pattern and the second pattern are transferred to a wafer, and in two adjacent exposure patterns, the first mark in one exposure pattern and the second mark in the other exposure pattern can be combined in an overlapping region to form a photoetching alignment mark containing a closed pattern; the closed pattern comprises at least three closed areas, the centers of the at least three closed areas are not collinear, and the photoetching alignment mark is used for realizing alignment when the next photoetching process is performed on the wafer. Therefore, accurate alignment can be realized.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a photolithography mask, a photolithography alignment mark, and a method for compensating for same-layer exposure errors. Background Art

[0002] In the semiconductor lithography process, overlay accuracy (OVL) is one of the key parameters to measure the lithography process. It refers to the alignment accuracy of the back layer pattern relative to the front layer pattern in the multi-layer lithography process. If the deviation is too large, it will directly affect the product yield. The alignment step before exposure is the key link to ensure overlay accuracy.

[0003] At present, the field uses the recognition of alignment marks to achieve alignment before exposure. Specifically, by designing an alignment pattern on the mask, after the front layer is exposed, an alignment mark is formed at the corresponding position of the wafer, and before the rear layer is exposed, the alignment pattern on the mask is accurately aligned with the front layer alignment mark on the wafer, so that the pattern on the mask can be accurately transferred to the photoresist during the thick layer exposure process.

[0004] During the step-by-step exposure process, the lens of the wafer carrier or exposure machine steps to each exposure position one by one according to the design value. Each exposure uses the same exposure unit (shot) and forms a corresponding exposure pattern on the wafer. In the current alignment process, each shot will measure a set of alignment marks, and 4-16 shots will be selected for measurement. The final alignment result reflects the deviations of the wafer level (wafer level), such as shift, rotation (rot) and magnifier (mag), namely wafer shift-X / Y, wafer Rot-X / Y and wafer Mag-X / Y. The corresponding 6 compensation values ​​can be calculated and manually input into the machine to achieve wafer surface compensation, where X and Y represent the X and Y directions perpendicular to each other, respectively. After completing the lower layer lithography, measure the OVL between the two layers and summarize the data into the APC (Advanced Process Control) system, and make corresponding compensation through APC when the next batch is delivered. However, the current alignment process still leads to excessive OVL deviation, causing yield abnormalities. Summary of the invention

[0005] In view of this, an embodiment of the present application provides a photolithography mask, a photolithography alignment mark, and a method for compensating for same-layer exposure errors in order to solve at least one problem existing in the background technology.

[0006] In a first aspect, an embodiment of the present application provides a photolithography mask, comprising an exposure unit for performing step-by-step exposure on a wafer, wherein when the wafer is subjected to step-by-step exposure along a set stepping direction, a pattern of the exposure unit is transferred to the wafer during each exposure to form an exposure pattern, and in two adjacent exposure patterns, the exposure pattern formed first and the exposure pattern formed later are arranged along the stepping direction and have an overlapping area, The exposure unit comprises at least one set of photolithography alignment patterns consisting of a first pattern and a second pattern, wherein the first pattern and the second pattern are respectively located on two sides of the exposure unit away from each other along the stepping direction, and the first pattern and the second pattern are both open patterns; The first pattern and the second pattern will form a first mark and a second mark correspondingly when being transferred to the wafer. In the two adjacent exposure patterns, the first mark in one exposure pattern and the second mark in the other exposure pattern can be combined in the overlapping area to form a lithography alignment mark containing a closed pattern, and the closed pattern includes at least three closed areas and the centers of at least three of the closed areas are not collinear. The lithography alignment mark is used to achieve alignment when the next lithography process is performed on the wafer.

[0007] In combination with the first aspect of the present application, in an optional implementation, the closed figure is a square, the number of the closed areas is four, and the sides of the four closed areas are respectively parallel or perpendicular to the stepping direction.

[0008] In conjunction with the first aspect of the present application, in an optional implementation, the first graphic includes a first line segment pattern, a second line segment pattern, and a third line segment pattern, the first line segment pattern and the second line segment pattern are parallel to each other and aligned end to end, and the third line segment pattern connects the midpoint of the first line segment pattern and the midpoint of the second line segment pattern; The second graphic includes a fourth line segment pattern, a fifth line segment pattern and a sixth line segment pattern, the fourth line segment pattern and the fifth line segment pattern are parallel to each other and aligned end to end, and the sixth line segment pattern connects the midpoint of the fourth line segment pattern and the midpoint of the fifth line segment pattern; The first line segment pattern and the fourth line segment pattern are perpendicular to each other.

[0009] In conjunction with the first aspect of the present application, in an optional implementation, the ratio of the distance between the first line segment pattern and the second line segment pattern to the length of the fourth line segment pattern is 70% to 95%; and / or, A ratio of a line width to a length of at least one of the first line segment pattern, the second line segment pattern, the third line segment pattern, the fourth line segment pattern, the fifth line segment pattern, and the sixth line segment pattern is 5% to 15%.

[0010] In a second aspect, an embodiment of the present application provides a lithography alignment mark, including a first mark and a second mark; The first mark and the second mark are both open patterns, the first mark and the second mark are respectively formed by two adjacent exposures in step exposure, and the first mark and the second mark can be combined to form a lithography alignment mark including a closed pattern, the closed pattern includes at least three closed areas, and the centers of at least three of the closed areas are not collinear; The photolithography alignment mark is used to achieve alignment when the next photolithography process is performed on the wafer, and the number of pixels in at least three of the closed areas is used to determine the complementary value of the alignment.

[0011] In conjunction with the second aspect of the present application, in an optional implementation, the closed figure is a square, the number of the closed areas is four, and the sides of the four closed areas are respectively parallel or perpendicular to the stepping direction.

[0012] In conjunction with the second aspect of the present application, in an optional implementation, the first mark includes a first line segment portion, a second line segment portion, and a third line segment portion, the first line segment portion and the second line segment portion are parallel to each other and aligned end to end, and the third line segment portion connects the midpoint of the first line segment portion and the midpoint of the second line segment portion; The second mark includes a fourth line segment portion, a fifth line segment portion and a sixth line segment portion, the fourth line segment portion and the fifth line segment portion are parallel to each other and aligned end to end, and the sixth line segment portion connects the midpoint of the fourth line segment portion and the midpoint of the fifth line segment portion; The first line segment portion and the fourth line segment portion are perpendicular to each other.

[0013] In conjunction with the second aspect of the present application, in an optional implementation, the ratio of the distance between the first line segment portion and the second line segment portion to the length of the fourth line segment portion is 70% to 95%; and / or, A ratio of a line width to a length of at least one of the first line segment portion, the second line segment portion, the third line segment portion, the fourth line segment portion, the fifth line segment portion, and the sixth line segment portion is 5% to 15%.

[0014] In a third aspect, an embodiment of the present application provides a method for compensating for same-layer exposure errors, the method comprising: Provide wafers; forming a first photoresist layer on the wafer; Performing a photolithography process using the photolithography mask as described in any one of the first aspects to form a plurality of exposure patterns in the photoresist layer, and forming a photolithography alignment mark in an overlapping area between an exposure pattern formed earlier and an exposure pattern formed later; transferring the photolithography alignment mark to the wafer; forming a second photoresist layer on the wafer; The photolithography process is performed again, and alignment is achieved based on the photolithography alignment mark, a complementary value for alignment is determined according to the number of pixel points of at least three of the closed areas within the photolithography alignment mark, and the alignment position is corrected according to the complementary value.

[0015] In conjunction with the third aspect of the present application, in an optional implementation, if the number of the closed areas within the photolithography alignment mark is less than three, feedback information is generated.

[0016] The beneficial effects of the embodiments of the present application are as follows: The photolithography mask provided in the embodiment of the present application includes an exposure unit including at least one group of photolithography alignment figures composed of a first figure and a second figure, the first figure and the second figure are respectively located on two sides of the exposure unit away from each other along the stepping direction, and the first figure and the second figure are both open figures; the first figure and the second figure will form a first mark and a second mark correspondingly when they are transferred to the wafer, and in two adjacent exposure figures, the first mark in one exposure figure and the second mark in the other exposure figure can be combined in the overlapping area to form a photolithography alignment mark containing a closed figure, the closed figure includes at least three closed areas and the centers of at least three closed areas are not collinear, and the photolithography alignment mark is used to achieve alignment when the next photolithography process is performed on the wafer. Thus, by overlapping two open figures, when the deviation of the stepping process within the layer is small, they can be combined to form a lithography alignment mark including a closed figure, and the closed figure can be used to facilitate alignment during the next lithography process; on the contrary, if the closed figure is not aligned during the next lithography process, it indicates that the deviation of the stepping process within the layer in the previous lithography process is large, thereby forming feedback to avoid misalignment; in addition, the closed figure includes at least three closed areas whose centers are not collinear, and the centers of the three closed areas can correspond to at least two non-collinear directions, which is conducive to feedback of the offset in at least two directions, determining the complement value, realizing alignment compensation, thereby correcting the alignment position, and realizing precise alignment to ensure good inter-layer overlay accuracy.

[0017] The lithography alignment mark provided in the embodiment of the present application includes a first mark and a second mark; the first mark and the second mark are both open figures, the first mark and the second mark are respectively formed by two adjacent exposures in the step-by-step exposure, and the first mark and the second mark can be combined to form a lithography alignment mark containing a closed figure, the closed figure includes at least three closed areas and the centers of at least three closed areas are not collinear; the lithography alignment mark is used to achieve alignment when the next lithography process is performed on the wafer, and the number of pixels in the at least three closed areas is used to determine the complementary value of the alignment. Thus, by overlapping two open figures, when the deviation of the stepping process within the layer is small, they can be combined to form a lithography alignment mark including a closed figure, and the closed figure can be used to facilitate alignment when the next lithography process is performed; on the contrary, if the closed figure is not aligned when the next lithography process is performed, it indicates that the deviation of the stepping process within the layer in the previous lithography process is large, so that feedback can be formed to avoid misalignment; in addition, the closed figure includes at least three closed areas whose centers are not colinear, and the centers of the three closed areas can correspond to at least two non-colinear directions, which is conducive to feedback of the offset in at least two directions, and is conducive to determining the complement value, realizing alignment compensation, thereby correcting the alignment position, realizing precise alignment, and ensuring good inter-layer overlay accuracy; and the deviation can be directly and clearly reflected by counting the pixels in the closed area, so the processing process is simpler and the processing result is more accurate.

[0018] The compensation method for the same-layer exposure error provided in this embodiment includes: providing a wafer; forming a first photoresist layer on the wafer; performing a photolithography process using the photolithography mask described in any one of the first aspects to form a plurality of exposure patterns in the photoresist layer, and forming a photolithography alignment mark in the overlapping area of ​​the first-formed exposure pattern and the later-formed exposure pattern; transferring the photolithography alignment mark to the wafer; forming a second photoresist layer on the wafer; performing the photolithography process again, and realizing alignment based on the photolithography alignment mark, determining a complementary value for alignment according to the number of pixel points in at least three closed areas within the photolithography alignment mark, and correcting the alignment position according to the complementary value. Therefore, the deviation of a single exposure pattern is reflected by the photolithography alignment mark, and the compensation value for achieving alignment is determined; before the photolithography process is performed again, the exposure unit of the second photolithography process is compensated by the reflected deviation, so that the photolithography alignment pattern on the photolithography mask of the second photolithography process can be accurately aligned with the formed photolithography alignment mark; and the deviation can be directly and clearly reflected by counting the pixels in the closed area, so that the processing process is simpler and the processing result is more accurate.

[0019] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings: Figure 1 A schematic diagram of an exposure unit in a photolithography mask provided in an optional embodiment of the present application; Figure 2 To adopt Figure 1 A schematic diagram of adjacent areas of four adjacent exposure patterns obtained by an exposure unit; Figure 3 A schematic diagram of a photolithography alignment mark provided for another optional embodiment of the present application; Figure 4 A schematic diagram of a first figure provided for another optional embodiment of the present application; Figure 5 A schematic diagram of a second figure provided for another optional embodiment of the present application; Figure 6 A schematic diagram of a photolithography alignment mark provided for an optional embodiment of the present application; Figure 7 A schematic diagram of a first figure provided for an optional embodiment of the present application; Figure 8 A schematic diagram of a second graph provided for an optional embodiment of the present application; Fig. 9 A schematic diagram of a photolithography alignment mark provided for yet another optional embodiment of the present application; Fig.10 A schematic diagram of a first figure provided for yet another optional embodiment of the present application; Fig.11 A schematic diagram of a second figure provided for yet another optional embodiment of the present application; Fig.12 To use the Y direction rotation Figure 1 A schematic diagram of adjacent areas of two adjacent exposure patterns obtained by an exposure unit; Fig.13 To adopt the X-direction scaling Figure 1 A schematic diagram of adjacent areas of two adjacent exposure patterns obtained by an exposure unit; Fig.14 For Y-direction scaling Figure 1 A schematic diagram of adjacent areas of two adjacent exposure patterns obtained by an exposure unit; Fig.15 For X-direction rotation Figure 1 A schematic diagram of adjacent areas of two adjacent exposure patterns obtained by an exposure unit; Fig.16A schematic diagram of a first mark provided for an optional embodiment of the present application; Fig.17 A schematic diagram of a second mark provided for an optional embodiment of the present application; Fig.18 A schematic diagram of a first mark provided for another optional embodiment of the present application; Fig.19 A schematic diagram of a second mark provided for another optional embodiment of the present application; Fig. 20 A schematic diagram of a first mark provided for another optional embodiment of the present application; Fig.21 A schematic diagram of a second mark provided for another optional embodiment of the present application; Fig. 22 A schematic flow chart of a method for compensating for same-layer exposure errors provided in an embodiment of the present application.

[0021] Description of reference numerals: 100, exposure unit; 110, marking area; 120, device area; 130, first graphic; 131, first line segment pattern; 132, second line segment pattern; 133, third line segment pattern; 140, second graphic; 141, fourth line segment pattern; 142, fifth line segment pattern; 143, sixth line segment pattern; 150, first mark; 151, first line segment portion; 152, second line segment portion; 153, third line segment portion; 160, second mark; 161, fourth line segment portion; 162, fifth line segment portion; 163, sixth line segment portion; 170, lithography alignment mark; 101, upper left exposure graphic; 102, upper right exposure graphic; 103, lower right exposure graphic; 104, lower left exposure graphic. DETAILED DESCRIPTION

[0022] The exemplary embodiments disclosed in the present application will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the specific embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present application and to fully convey the scope disclosed in the present application to those skilled in the art.

[0023] In the following description, a large number of specific details are given to provide a more thorough understanding of the present application. However, it is obvious to those skilled in the art that the present application can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present application, some technical features known in the art are not described; that is, all features of the actual embodiments are not described here, and well-known functions and structures are not described in detail.

[0024] In the drawings, the sizes of layers, regions, elements and their relative sizes may be exaggerated for clarity. Like reference numerals denote like elements throughout.

[0025] It should be understood that when an element or layer is referred to as "on ...", "adjacent to ...", "connected to" or "coupled to" other elements or layers, it can be directly on, adjacent to, connected to or coupled to other elements or layers, or there can be intervening elements or layers. On the contrary, when an element is referred to as "directly on ...", "directly adjacent to ...", "directly connected to" or "directly coupled to" other elements or layers, there is no intervening element or layer. It should be understood that although the terms first, second, third, etc. can be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present application, the first element, component, region, layer or part discussed below can be represented as the second element, component, region, layer or part. And when the second element, component, region, layer or part is discussed, it does not indicate that the present application necessarily has the first element, component, region, layer or part.

[0026] Spatial relationship terms such as "under", "below", "below", "under", "above", "above", etc., may be used here for convenience of description to describe the relationship between an element or feature shown in the figure and other elements or features. It should be understood that in addition to the orientation shown in the figure, the spatial relationship terms are intended to include different orientations of the device in use and operation. For example, if the device in the accompanying drawings is turned over, then the elements or features described as "under other elements" or "under it" or "under it" will be oriented as "on" other elements or features. Therefore, the exemplary terms "under" and "under" may include both upper and lower orientations. The device can be oriented otherwise (rotated 90 degrees or other orientations) and the spatial descriptors used herein are interpreted accordingly.

[0027] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present application. When used herein, the singular forms "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0028] In order to thoroughly understand the present application, detailed steps and detailed structures will be presented in the following description to illustrate the technical solution of the present application. The preferred embodiments of the present application are described in detail below, but in addition to these detailed descriptions, the present application may also have other implementation methods.

[0029] The embodiment of the present application provides a photolithography mask, and the photolithography alignment marks formed by the photolithography mask in the photolithography process can be used to achieve alignment when the next photolithography process (i.e., the back-layer photolithography) is performed on the wafer. In addition, the deviation of each exposure pattern formed in the front layer can be monitored, and in the alignment process before performing the back-layer photolithography, the exposure unit can be compensated for alignment to achieve precise alignment. The "alignment" here refers to the process of aligning the pattern on the photolithography mask of the subsequent photolithography process with the pattern already formed on the wafer before the subsequent photolithography is performed, so as to ensure that in the multi-layer photolithography process, the pattern formed in the subsequent layer can accurately cover the correct position of the previous layer pattern; the "photolithography alignment mark" is the pattern formed on the wafer after the photolithography process. Correspondingly, a photolithography alignment pattern for forming a photolithography alignment mark is provided on the photolithography mask. During the alignment process, two cameras located above the photolithography mask can be used to capture the photolithography alignment pattern on the photolithography mask and the photolithography alignment mark on the wafer respectively, and the wafer can be moved to align the two, thereby achieving alignment.

[0030] The photolithography mask includes an exposure unit for performing step-by-step exposure on the wafer. Step-by-step exposure is an exposure method that realizes exposure of the entire wafer through multiple local exposures, that is, after the exposure is completed at the current exposure position on the wafer, the preset step length is moved along the set step direction to reach the next exposure position and perform exposure. Therefore, when the wafer is step-by-step exposed along the set step direction, the pattern of the exposure unit is transferred to the wafer at each exposure to form an exposure pattern. Among the two adjacent exposure patterns, the exposure pattern formed first and the exposure pattern formed later are arranged along the step direction. By making the wafer and the lens of the exposure machine move relative to each other, the lens of the exposure machine is aligned with each exposure position on the wafer one by one for exposure.

[0031] Please refer to Figure 1, the exposure unit 100 may include a device area 120 and a marking area 110 located at the periphery of the device area 120. The device area 120 of the exposure unit 100 includes a pattern to be exposed and formed on the chip area of ​​the wafer, and the marking area 110 includes a lithography alignment pattern for forming a lithography alignment mark. It can be understood that the lithography alignment mark is usually set on the cutting road located at the periphery of the chip area of ​​the wafer to separate the lithography alignment mark from the pattern in the chip area, which is more conducive to the identification and positioning of the alignment mark by equipment such as a lithography machine, and it does not occupy the effective area of ​​the chip. Therefore, the device area 120 can correspond to the chip area of ​​the wafer, and the marking area 110 can correspond to the cutting road of the wafer. During the step-by-step exposure, the two adjacent exposure patterns formed have an overlapping area, and the overlapping area is formed by the overlapping of the marking areas on both sides of the two adjacent exposure patterns.

[0032] In the exposure unit 100 of the present embodiment, the device area 120 is, for example, a rectangle, and each step direction of the step exposure is, for example, parallel to the edge of the rectangle to save the wafer area. In addition, the marking area 110 is, for example, a rectangular ring (specifically, the inner circle boundary of the marking area 110 is the boundary of the device area 120, and the outer circle boundary of the marking area 110 and the inner circle boundary have the same symmetry center and the two are in the form of a rectangle nested inside and outside), then each step direction is also parallel to the corresponding edge of the marking area 110.

[0033] Please refer to Figure 1 and Figure 2 In the photolithography mask provided in the embodiment of the present application, the exposure unit 100 used to implement step-by-step exposure of the wafer includes at least one group of photolithography alignment figures composed of a first figure 130 and a second figure 140, the first figure 130 and the second figure 140 are respectively located on two sides of the exposure unit 100 away from each other along the stepping direction, and the first figure 130 and the second figure 140 are both open figures; the first figure 130 and the second figure 140 will form a first mark 150 and a second mark 160 correspondingly when they are transferred to the wafer, and in two adjacent exposure figures, the first mark 150 in one exposure figure and the second mark 160 in the other exposure figure can be combined in the overlapping area to form a photolithography alignment mark 170 containing a closed figure, the closed figure includes at least three closed areas and the centers of at least the three closed areas are not collinear, and the photolithography alignment mark 170 is used to achieve alignment when the next photolithography process is performed on the wafer.

[0034] It can be understood that the present embodiment utilizes two overlapping open graphics, so that when the deviation of the intra-layer stepping process is small, they can be combined to form a lithography alignment mark 170 including a closed graphic, and the closed graphic can be used to facilitate alignment when the next lithography process is performed; on the contrary, if the closed graphic is not aligned when the next lithography process is performed, it indicates that the deviation of the intra-layer stepping process in the previous lithography process is large, so that feedback can be formed to avoid misalignment; in addition, the closed graphic includes at least three closed areas whose centers are not colinear, and the centers of the three closed areas can correspond to at least two non-colinear directions, which is conducive to feedback of the offset in at least two directions, and is conducive to determining the complement value, realizing alignment compensation, thereby correcting the alignment position, and realizing precise alignment to ensure good inter-layer overlay accuracy.

[0035] There are usually 12 deviation values ​​obtained by alignment measurement before the next photolithography, including wafershift-X, wafer shift-Y, wafer Rot-X, wafer Rot-Y, wafer Mag-X, wafer Mag-Y, shotshift-X, shot shift-Y, shot Rot-X, shot Rot-Y, shot Mag-X, shot Mag-Y. Among them, the offset (shot shift) of the exposure unit 100 can be reflected by the offset (wafer shift) of the wafer surface, so the deviation value can also be regarded as a total of 10 items. In conventional alignment processes, 4-16 shots are usually selected to measure the alignment accuracy of a group of lithography alignment marks in each shot. However, this can only reflect the deviation at the wafer level, while the deviation at the exposure unit level (shot level) needs to be calculated based on the interlayer OVL data measured after the layer is formed, and then compensated in subsequent processes. That is, the subsequent 4 deviation values ​​cannot be obtained, and the exposure unit cannot be compensated immediately after alignment. In this process, the OVL deviation may have exceeded the machine threshold, and the wafer needs to be reworked, affecting production efficiency and cost. Therefore, the photolithography mask provided in this embodiment can be used to form a photolithography alignment mark 170 in the previous photolithography process. In the next photolithography process, the machine can use at least three closed areas whose centers are not colinear in the photolithography alignment mark 170 to calculate the rotation degree and zoom ratio of the later-formed exposure pattern in the X-direction and the Y-direction relative to the earlier-formed exposure pattern in two adjacent exposure patterns, thereby reflecting the rotation degree (shot Rot) of the exposure unit 100 and the zoom ratio (shot Mag) of the exposure unit 100.

[0036] The machine can calculate the alignment compensation value through the measured deviation values ​​of shot Rot-X, shot Rot-Y, shot Mag-X and shot Mag-Y, among which, the alignment compensation value in the X direction = the deviation value in the X direction * the radius of the exposure unit in the X direction, and the alignment compensation value in the Y direction = the deviation value in the Y direction * the radius of the exposure unit in the Y direction. Of course, when the exposure unit is rectangular, the radius of the exposure unit is 1 / 2 of the side length of the exposure unit.

[0037] The first graphic 130 and the second graphic 140 are both open graphics, so the corresponding first mark 150 and the second mark 160 are also open graphics. The two open graphics are combined to form a photolithography alignment mark 170 including a closed graphic, which can effectively avoid the machine from misidentifying as no deviation when the deviation is large. If at least one of the first mark 150 and the second mark 160 is a closed graphic, or even both of them are closed graphics, then when the deviation is large, the first mark 150 and the second mark 160 may not be nested, but due to the existence of the closed graphic, they may be misidentified as no deviation during machine measurement, which greatly affects OVL.

[0038] It can be understood that there are usually multiple rows and columns of exposure positions for forming exposure patterns distributed on the wafer. Step exposure performs exposure at each exposure position according to a set step direction. In order to traverse all exposure positions on the wafer, step exposure can be performed from top to bottom row by row in a non-continuous manner. For each row, exposure is performed from left to right, that is, including a step direction from left to right and a step direction from top to bottom. Step exposure can also be performed from top to bottom row by row in a continuous manner. After completing a row of exposure from left to right, move to the right end of the next row and expose from right to left, that is, including two opposite step directions from left to right and from right to left and a step direction from top to bottom. Step exposure can also be performed from bottom to top row by row non-continuously or continuously. Step exposure can include four step directions, and the four step directions can be divided into two pairs, the two step directions in each pair are in opposite directions, and one pair of step directions is perpendicular to the other pair of step directions. Thus, if Figure 1 As shown, in order to better reflect the deviation between two adjacent exposure patterns, the exposure unit 100 may include two groups of lithography alignment patterns consisting of a first pattern 130 and a second pattern 140. In each group of lithography alignment patterns, the first pattern 130 and the second pattern 140 are respectively located on two sides of the exposure unit 100 away from each other along the stepping direction, and the stepping direction corresponding to one group of lithography alignment patterns is perpendicular to the stepping direction corresponding to the other group of lithography alignment patterns.

[0039] In this embodiment, the X direction points to the same direction as the stepping direction from left to right, and the Y direction points to the same direction as the stepping direction from bottom to top.

[0040] As another alternative embodiment, please refer to Figure 3 , the closed figure is "L-shaped", the number of closed areas is three, and the sides of the three closed areas are parallel or perpendicular to the stepping direction. Furthermore, the extension direction of the center line connecting two adjacent closed areas is parallel or perpendicular to the stepping direction. Therefore, the deviation of the exposure unit 100 in the Y direction can be reflected by the two closed figures located on the vertical sides of the "L" shape, and the deviation of the exposure unit 100 in the X direction can be reflected by the two closed figures located on the horizontal sides of the "L" shape.

[0041] Optionally, refer to Figure 4 and Figure 5 The first graphic 130 includes a first line segment pattern 131, a second line segment pattern 132 and a third line segment pattern 133. The first line segment pattern 131 and the second line segment pattern 132 are parallel to each other and their head ends are aligned. The length of the second line segment pattern 132 is 1 / 2 of the length of the first line segment pattern 131. The third line segment pattern 133 connects the midpoint of the first line segment pattern 131 and the tail end of the second line segment pattern 132. The second graphic 140 includes a fourth line segment pattern 141, a fifth line segment pattern 142 and a sixth line segment pattern 143. The fourth line segment pattern 141 and the fifth line segment pattern 142 are parallel to each other and their head ends are aligned. The length of the fifth line segment pattern 142 is 1 / 2 of the length of the fourth line segment pattern 141. The sixth line segment pattern 143 connects the midpoint of the fourth line segment pattern 141 and the tail end of the fifth line segment pattern 142. The first line segment pattern 131 and the fourth line segment pattern 141 are perpendicular to each other. Figure 3 , the first mark 150 formed by the first figure 130 and the second mark 160 formed by the second figure 140 can be combined to form an "L-shaped" closed figure, the number of closed areas is three, the sides of the three closed areas are parallel or perpendicular to the stepping direction, and the extension direction of the center line connecting two adjacent closed areas is parallel or perpendicular to the stepping direction. Under ideal conditions (no deviation), the formed closed figure includes three square closed areas of equal area, the closed areas on the left and right sides can reflect the deviation in the X direction, and the closed areas on the upper and lower sides can reflect the deviation in the Y direction.

[0042] As an alternative embodiment, please refer to Figure 6, the closed figure is a square, the number of closed areas is four, and the sides of the four closed areas are parallel or perpendicular to the stepping direction. Furthermore, the extension direction of the center line connecting two adjacent closed areas is parallel or perpendicular to the stepping direction. Therefore, it is more conducive to calculating the deviation value of the exposure unit 100 in the X direction and the Y direction. Specifically, four closed areas of equal area and all of which are square are formed in the closed figure. The machine can measure the four closed areas. The closed areas on the left and right sides can reflect the deviation in the X direction, and the closed areas on the upper and lower sides can reflect the deviation in the Y direction.

[0043] Optionally, refer to Figure 7 and Figure 8 The first graphic 130 includes a first line segment pattern 131, a second line segment pattern 132 and a third line segment pattern 133. The first line segment pattern 131 and the second line segment pattern 132 are parallel to each other and aligned end to end. The third line segment pattern 133 connects the midpoint of the first line segment pattern 131 and the midpoint of the second line segment pattern 132. The second graphic 140 includes a fourth line segment pattern 141, a fifth line segment pattern 142 and a sixth line segment pattern 143. The fourth line segment pattern 141 and the fifth line segment pattern 142 are parallel to each other and aligned end to end. The sixth line segment pattern 143 connects the midpoint of the fourth line segment pattern 141 and the midpoint of the fifth line segment pattern 142. The first line segment pattern 131 and the fourth line segment pattern 141 are perpendicular to each other. Figure 6 , the first mark 150 formed by the first figure 130 and the second mark 160 formed by the second figure 140 can form a square closed figure, and the number of closed areas is four, and the sides of the four closed areas are respectively parallel or perpendicular to the stepping direction, and the extension direction of the center line connecting two adjacent closed areas is parallel or perpendicular to the stepping direction. Under ideal conditions (no deviation), the formed closed figure includes four square closed areas of equal area, the closed areas on the left and right sides can reflect the deviation in the X direction, and the closed areas on the upper and lower sides can reflect the deviation in the Y direction.

[0044] Furthermore, the shape of the second pattern 140 is the same as that of the first pattern 130, and the direction of the second pattern 140 is rotated 90 degrees relative to the first pattern 130 around the center point between the midpoint of the first line segment pattern 131 and the midpoint of the second line segment pattern 132. Thus, the difficulty of designing the photolithography mask is reduced.

[0045] Optionally, the ratio of the distance between the first line segment pattern 131 and the second line segment pattern 132 to the length of the fourth line segment pattern 141 is 70% to 95%. It can be understood that if the ratio of the distance between the first line segment pattern 131 and the second line segment pattern 132 to the length of the fourth line segment pattern 141 is too large, in the case of a large deviation, after the first mark 150 formed by the first graphic 130 and the second mark 160 formed by the second graphic 140 are combined, the first and last ends of the part of the second mark 160 corresponding to the fourth line segment pattern 141 may not be connected to the first mark 150, that is, it is very likely that a closed figure with three closed areas cannot be formed; if the ratio of the distance between the first line segment pattern 131 and the second line segment pattern 132 to the length of the fourth line segment pattern 141 is too small, even in the case of a large deviation, after the first mark 150 formed by the first graphic 130 and the second mark 160 formed by the second graphic 140 are combined, a closed figure that meets the requirements can still be formed, and the machine may mistakenly recognize that the deviation is small or there is no deviation. Therefore, controlling the ratio within this range is more conducive to the machine's measurement of deviation values.

[0046] Optionally, a ratio of line width to length of at least one of the first line segment pattern 131 , the second line segment pattern 132 , the third line segment pattern 133 , the fourth line segment pattern 141 , the fifth line segment pattern 142 and the sixth line segment pattern 143 is 5% to 15%. It can be understood that if the ratio of line width to length is too large, in the closed figure formed by combining the first mark 150 formed by the first figure 130 and the second mark 160 formed by the second figure 140, the size of each closed area is small. Even in the case of a small deviation, the part of the second mark 160 corresponding to the sixth line segment pattern 143 may still overlap with the part of the first mark 150 corresponding to the first line segment pattern 131, making it difficult to form a closed figure that meets the requirements, and the machine may mistakenly identify it as a case of large deviation. If the ratio of line width to length is too small, the process of forming a line segment pattern on the photolithography mask is more difficult, and it is more difficult to form a clear mark in the photolithography process, which affects the measurement of the machine and the alignment of the subsequent layer photolithography. In addition, in the case of a large deviation, after the first mark 150 formed by the first figure 130 and the second mark 160 formed by the second figure 140 are combined, the first and last ends of the part of the second mark 160 corresponding to the fourth line segment pattern 141 may not be connected to the first mark 150, that is, it is very likely that a closed figure with three closed areas cannot be formed. Therefore, controlling the ratio within this range is more conducive to the machine's measurement of deviation values.

[0047] Of course, in this embodiment, the number of closed areas is not limited to four, and may be five, six, or seven, etc. As another optional embodiment, Fig. 9 As shown, eight closed areas can be included in the closed figure.

[0048] Optionally, refer to Fig.10 and Fig.11 The first graphic 130 includes a first line segment pattern 131, a second line segment pattern 132 and a third line segment pattern 133. The first line segment pattern 131 and the second line segment pattern 132 are parallel to each other and aligned end to end. The third line segment pattern 133 connects the first line segment pattern 131 and the second line segment pattern 132. The second graphic 140 includes a fourth line segment pattern 141, a fifth line segment pattern 142 and a sixth line segment pattern 143. The fourth line segment pattern 141 and the fifth line segment pattern 142 are parallel to each other and aligned end to end. The sixth line segment pattern 143 connects the fourth line segment pattern 141 and the fifth line segment pattern 142. The first line segment pattern 131 and the fourth line segment pattern 141 are perpendicular to each other. Fig. 9 The photolithography alignment mark 170 composed of the first mark 150 formed by the first pattern 130 and the second mark 160 formed by the second pattern 140 includes a closed pattern, and the number of closed areas is multiple.

[0049] Furthermore, the shape of the second pattern 140 is the same as that of the first pattern 130, and the direction of the second pattern 140 is rotated 90 degrees relative to the first pattern 130 around the center point between the midpoint of the first line segment pattern 131 and the midpoint of the second line segment pattern 132. Thus, the difficulty of designing the photolithography mask is reduced.

[0050] It is understandable that the first graphic 130 and the second graphic 140 are not limited to Figure 4 and Figure 5 , Figure 7 and Figure 8 , Fig.10 and Fig.11 In practical applications, any two appropriate open graphs can be selected as needed for the structure shown.

[0051] Figure 2 To adopt Figure 1Schematic diagram of adjacent areas of four adjacent exposure patterns obtained by the exposure unit. Taking the stepping order from left to right, from top to bottom (row break), and from right to left as an example, that is, for four exposure patterns in adjacent rows and adjacent columns, the order of forming the exposure patterns is upper left exposure pattern 101, upper right exposure pattern 102, lower right exposure pattern 103, and lower left exposure pattern 104, and it can be seen that, in an ideal case (no deviation occurs), a first mark 150 in upper right exposure pattern 102 is combined with a second mark 160 in upper left exposure pattern 101 to form a photolithography alignment mark 170, a first mark 150 in lower right exposure pattern 103 is combined with a second mark 160 in upper right exposure pattern 102 to form a photolithography alignment mark 170, a second mark 160 in lower left exposure pattern 104 is combined with a first mark 150 in lower right exposure pattern 103 to form a photolithography alignment mark 170, and a first mark 150 in lower left exposure pattern 104 is combined with a second mark 160 in upper left exposure pattern 101 to form a photolithography alignment mark 170. By detecting the deviation between at least three closed areas in the lithography alignment mark 170, it can be used to determine whether a software or mechanical failure occurs in the exposure machine or the wafer carrier, so as to deal with it in time to avoid a large amount of waste and avoid losses.

[0052] Specifically, please refer to Figure 2 , Fig.12 and Fig.13 , Figure 2 The photolithography alignment mark 170 between the upper left exposure pattern 101 and the upper right exposure pattern 102 is in an ideal state (no deviation occurs). Fig.12 As shown in FIG. 1 , the closed areas on the left and right sides have no deviation, but the closed areas on the upper and lower sides have deviation. Since the upper left exposure pattern 101 and the upper right exposure pattern 102 are exposure patterns formed successively in the X direction, combined with the deviation of the closed areas, it can be determined that the exposure unit 100 has rotated in the Y direction at this time, and shot Rot-Y can be measured; Fig.13 As shown, the closed areas on the left and right sides have deviations, while the closed areas on the upper and lower sides have no deviations. Since the upper left exposure pattern 101 and the upper right exposure pattern 102 are exposure patterns formed successively in the X direction, combined with the deviation of the closed areas, it can be determined that the exposure unit 100 has been scaled in the X direction at this time, and the shot Mag-X can be measured.

[0053] Specifically, please refer to Figure 2 , Fig.14 and Fig.15 , Figure 2The photolithography alignment mark 170 between the upper right exposure pattern 102 and the lower right exposure pattern 103 is in an ideal state (no deviation occurs). Fig.14 As shown in FIG. 1 , the closed areas on the left and right sides have no deviation, but the closed areas on the upper and lower sides have deviation. Since the upper right exposure pattern 102 and the lower right exposure pattern 103 are exposure patterns formed successively in the Y direction, combined with the deviation of the closed areas, it can be determined that the exposure unit 100 is scaled in the Y direction at this time, and shot Mag-Y can be measured; Fig.15 As shown, the closed areas on the left and right sides have deviations, while the closed areas on the upper and lower sides have no deviations. Since the upper right exposure pattern 102 and the lower right exposure pattern 103 are exposure patterns formed successively in the Y direction, combined with the deviation of the closed areas, it can be determined that the exposure unit 100 has rotated in the X direction at this time, and shot Rot-X can be measured.

[0054] When executing the next photolithography process, the offset value can be determined by calculating the number of pixels in at least three closed areas. The machine can obtain the image of the photolithography alignment mark 170 formed and feed it back to the computer system. In the computer system, the image is mostly presented in pixels of different grayscales. If the deviation value is reflected by measuring the distance between the first mark 150 and the second mark 160, it is usually necessary to clarify the boundaries of each mark graphic, but there may be pixel interference at the boundary, resulting in unclear boundary definition, which in turn affects the distance measurement; while counting the number of pixels in the closed area is simpler and more direct for the computer system, and the measurement result obtained is more accurate.

[0055] The present application embodiment also provides a photolithography alignment mark 170, please refer to Figure 2The photolithography alignment mark 170 includes a first mark 150 and a second mark 160; the first mark 150 and the second mark 160 are both open figures, the first mark 150 and the second mark 160 are respectively formed by two adjacent exposures in the step-by-step exposure, and the first mark 150 and the second mark 160 can be combined to form a photolithography alignment mark 170 containing a closed figure, the closed figure includes at least three closed areas and the centers of at least three closed areas are not collinear; the photolithography alignment mark 170 is used to achieve alignment when the next photolithography process is performed on the wafer, and the number of pixels in at least three closed areas is used to determine the complementary value of the alignment. Thus, by overlapping two open figures, when the deviation of the stepping process within the layer is small, they can be combined to form a lithography alignment mark 170 including a closed figure, and the closed figure can be used to facilitate alignment when the next lithography process is performed; on the contrary, if the closed figure is not aligned when the next lithography process is performed, it indicates that the deviation of the stepping process within the layer in the previous lithography process is large, so that feedback can be formed to avoid misalignment; in addition, the closed figure includes at least three closed areas whose centers are not colinear, and the centers of the three closed areas can correspond to at least two non-colinear directions, which is conducive to feedback of the offset in at least two directions, and is conducive to determining the complement value, realizing alignment compensation, thereby correcting the alignment position, and realizing precise alignment to ensure good inter-layer overlay accuracy; and the deviation can be directly and clearly reflected by counting the pixels in the closed area, so that the processing process is simpler and the processing result is more accurate.

[0056] Optionally, the closed figure is a square, the number of closed areas is four, and the sides of the four closed areas are respectively parallel or perpendicular to the stepping direction.

[0057] As an alternative embodiment, please refer to Fig.16 and Fig.17 The first mark 150 includes a first line segment portion 151, a second line segment portion 152 and a third line segment portion 153. The first line segment portion 151 and the second line segment portion 152 are parallel to each other and aligned end to end. The third line segment portion 153 connects the midpoint of the first line segment portion 151 and the midpoint of the second line segment portion 152. The second mark 160 includes a fourth line segment portion 161, a fifth line segment portion 162 and a sixth line segment portion 163. The fourth line segment portion 161 and the fifth line segment portion 162 are parallel to each other and aligned end to end. The sixth line segment portion 163 connects the midpoint of the fourth line segment portion 161 and the midpoint of the fifth line segment portion 162. The first line segment portion 151 and the fourth line segment portion 161 are perpendicular to each other.

[0058] As another alternative embodiment, please refer to Fig.18 and Fig.19The first mark 150 includes a first line segment portion 151, a second line segment portion 152 and a third line segment portion 153. The first line segment portion 151 and the second line segment portion 152 are parallel to each other and their head ends are aligned. The length of the second line segment portion 152 is 1 / 2 of the length of the first line segment portion 151. The third line segment portion 153 connects the midpoint of the first line segment portion 151 and the tail end of the second line segment portion 152. The second mark 160 includes a fourth line segment portion 161, a fifth line segment portion 162 and a sixth line segment portion 163. The fourth line segment portion 161 and the fifth line segment portion 162 are parallel to each other and their head ends are aligned. The length of the fifth line segment portion 162 is 1 / 2 of the length of the fourth line segment portion 161. The sixth line segment portion 163 connects the midpoint of the fourth line segment portion 161 and the tail end of the fifth line segment portion 162. The first line segment portion 151 and the fourth line segment portion 161 are perpendicular to each other.

[0059] As another optional embodiment, please refer to Fig. 20 and Fig.21 The first mark 150 includes a first line segment portion 151, a second line segment portion 152 and a third line segment portion 153. The first line segment portion 151 and the second line segment portion 152 are parallel to each other and aligned end to end. The third line segment portion 153 connects the beginning of the first line segment portion 151 and the end of the second line segment portion 152. The second mark 160 includes a fourth line segment portion 161, a fifth line segment portion 162 and a sixth line segment portion 163. The fourth line segment portion 161 and the fifth line segment portion 162 are parallel to each other and aligned end to end. The sixth line segment portion 163 connects the end of the fourth line segment portion 161 and the beginning of the fifth line segment portion 162. The first line segment portion 151 and the fourth line segment portion 161 are perpendicular to each other.

[0060] It is understandable that the first mark 150 and the second mark 160 are not limited to Fig.16 and Fig.17 , Fig.18 and Fig.19 , Fig. 20 and Fig.21 In practical applications, any two appropriate open graphs can be selected as needed for the structure shown.

[0061] Optionally, the ratio of the distance between the first line segment portion 151 and the second line segment portion 152 to the length of the fourth line segment portion 161 is 70% to 95%. It can be understood that if the ratio of the distance between the first line segment portion 151 and the second line segment portion 152 to the length of the fourth line segment portion 161 is too large, in the case of a large deviation, after the first mark 150 and the second mark 160 are combined, the two ends of the fourth line segment portion 161 may not be connected to the first line segment portion 151 and the second line segment portion 152 to form a closed area, and it is very likely that a closed figure that meets the requirements cannot be formed; if the ratio is too small, even in the case of a large deviation, the first mark 150 and the second mark 160 can still form a closed figure that meets the requirements after the combination, and the machine may mistakenly identify it as a small deviation or no deviation. Therefore, controlling the ratio within this range is more conducive to the machine measuring the deviation value.

[0062] Optionally, a ratio of line width to length of at least one of the first line segment portion 151 , the second line segment portion 152 , the third line segment portion 153 , the fourth line segment portion 161 , the fifth line segment portion 162 and the sixth line segment portion 163 is 5% to 15%. It can be understood that if the ratio of line width to length is too large, in the closed figure formed by the combination of the first mark 150 and the second mark 160, the size of each closed area is small. Even in the case of small deviation, the sixth line segment portion 163 may overlap with the first line segment portion 151 or the second line segment portion 152, and the third line segment portion 153 may overlap with the fourth line segment portion 161 or the fifth line segment portion 162, resulting in that part of the closed figure may not be formed, and the machine may mistakenly identify it as a large deviation. If the ratio of line width to length is too small, the process of forming a line segment pattern on the photolithography mask is more difficult, and it is more difficult to form a clear mark in the photolithography process, which affects the measurement of the machine and the alignment of the subsequent layer photolithography. In addition, in the case of large deviation, after the combination of the first mark 150 and the second mark 160, the first and last ends of the fourth line segment portion 161 may not be connected to the first mark 150, that is, it is very likely that a closed figure with three closed areas cannot be formed. Therefore, controlling the ratio within this range is more conducive to the machine to measure the deviation value.

[0063] The present application also provides a method for compensating for the same-layer exposure error. Fig. 22 , the method comprising: Step S1: providing a wafer; Step S2: forming a first photoresist layer on the wafer; Step S3: performing a photolithography process using the photolithography mask provided in the above embodiment to form a plurality of exposure patterns in the photoresist layer, and forming a photolithography alignment mark in an overlapping area between the exposure pattern formed earlier and the exposure pattern formed later; Step S4: transferring the photolithography alignment mark to the wafer; Step S5: forming a second photoresist layer on the wafer; Step S6: performing the photolithography process again, and realizing alignment based on the photolithography alignment mark, determining the complementary value of the alignment according to the number of pixel points in at least three closed areas within the photolithography alignment mark, and correcting the alignment position according to the complementary value.

[0064] Therefore, on the basis of the aforementioned embodiment, in the process of executing the photolithography process, a corresponding photolithography alignment mark is formed on the wafer using a photolithography mask, and the formed photolithography alignment mark is used to reflect the deviation of a single exposure pattern, and the compensation value for achieving alignment is determined. Before executing the photolithography process again, the exposure unit of the second photolithography process is compensated by the reflected deviation, so that the photolithography alignment pattern on the photolithography mask of the second photolithography process can be accurately aligned with the formed photolithography alignment mark; and, by counting the pixel points in the closed area, the deviation can be directly and clearly reflected, the processing process is simpler, and the processing result is more accurate.

[0065] It can be understood that the “same-layer exposure error” refers to the error between exposure units during the step-by-step exposure process using the same exposure unit in the same photolithography process.

[0066] In this embodiment, the wafer is, for example, a silicon wafer, and the wafer may undergo one or more semiconductor processes such as deposition, photolithography, and etching.

[0067] In step S3: a photolithography process is performed using the photolithography mask provided in the above-mentioned embodiment to form a plurality of exposure patterns in the photoresist layer, and a photolithography alignment mark is formed in the overlapping area of ​​the exposure pattern formed earlier and the exposure pattern formed later. During the exposure process, the incident light is incident on the photoresist layer through the photolithography mask. In this embodiment, the photoresist layer is, for example, a positive photoresist, and the first pattern and the second pattern on the exposure unit correspond to the area in the photolithography mask through which the incident light can pass. After exposure and development, the photoresist corresponding to the area is removed, and a first mark is formed at the position corresponding to the first pattern, and a second mark is formed at the position corresponding to the second pattern. After the first mark and the second mark are combined, a photolithography alignment mark containing a closed pattern is formed, and the closed area in the closed pattern is composed of photoresist.

[0068] In step S4, the photolithography alignment mark is transferred to the wafer, and an etching process is performed, using the photoresist layer exposed in step 3 as a mask for etching to form a preset pattern on the wafer and transfer the photolithography alignment mark to the wafer.

[0069] Next, step S5 is performed: forming a second photoresist layer on the wafer. It can be understood that since a photolithography alignment mark is formed on the wafer in step S4, the second photoresist layer is conformally formed on the photolithography alignment mark, and the photolithography alignment mark can be detected when the photolithography process is performed again later.

[0070] In step S6, the photolithography process is performed again, and alignment is achieved based on the photolithography alignment mark. The alignment compensation value is determined according to the number of pixels in at least three closed areas within the photolithography alignment mark, and the alignment position is corrected according to the compensation value. When the photolithography process is performed again, the photolithography mask is moved to the corresponding exposure area. The photolithography mask is provided with a photolithography alignment pattern for alignment. Under ideal conditions, the photolithography alignment pattern on the photolithography mask of the photolithography process again can be accurately aligned with the photolithography alignment mark formed on the wafer. However, during the step-by-step exposure process, the machine may produce mechanical deviations, causing the exposure unit to shift, rotate and scale. If the exposure unit is not compensated when the photolithography process is performed again, it is difficult to achieve accurate alignment, which in turn affects the product yield. Compared with the traditional method of manually calculating the deviation value and then manually inputting it into the machine to perform corresponding alignment compensation, in this embodiment, the machine can automatically determine the alignment compensation value according to the number of pixels in the closed area at each alignment, correct the alignment position, and improve production efficiency.

[0071] Optionally, if the number of enclosed areas within the lithography alignment mark is less than three, feedback information is generated. If the number of enclosed areas within the lithography alignment mark is less than three, the machine has a large deviation, and the operator can be reminded to terminate the program by generating feedback information, or the machine can automatically terminate the program according to the feedback information to avoid continuing to execute subsequent processes and causing waste. Feedback information is used to indicate that the deviation is too large and it is difficult to find the lithography alignment mark used to achieve alignment.

[0072] It should be noted that the photolithography mask embodiments, photolithography alignment marks, and same-layer exposure error compensation method embodiments provided in the present application belong to the same concept; the technical features in the technical solutions recorded in the embodiments can be arbitrarily combined without conflict.

[0073] It should be understood that the above embodiments are exemplary and are not intended to include all possible implementations. Various modifications and changes may also be made on the basis of the above embodiments without departing from the scope of the present disclosure. Similarly, the various technical features of the above embodiments may also be combined arbitrarily to form other embodiments of the present application that may not be clearly described. Therefore, the above embodiments only express several implementations of the present application and do not limit the scope of protection of the patent of this application.

Claims

1. A photolithography mask, comprising an exposure unit for performing step-by-step exposure on a wafer, wherein when the wafer is subjected to step-by-step exposure along a set stepping direction, a pattern of the exposure unit is transferred to the wafer at each exposure to form an exposure pattern, and in two adjacent exposure patterns, the exposure pattern formed first and the exposure pattern formed later are arranged along the stepping direction and have an overlapping area, characterized in that: The exposure unit comprises at least one set of photolithography alignment patterns consisting of a first pattern and a second pattern, wherein the first pattern and the second pattern are respectively located on two sides of the exposure unit away from each other along the stepping direction, and the first pattern and the second pattern are both open patterns; The first pattern and the second pattern will form a first mark and a second mark correspondingly when being transferred to the wafer. In the two adjacent exposure patterns, the first mark in one exposure pattern and the second mark in the other exposure pattern can be combined in the overlapping area to form a lithography alignment mark containing a closed pattern, and the closed pattern includes at least three closed areas and the centers of at least three of the closed areas are not collinear. The lithography alignment mark is used to achieve alignment when the next lithography process is performed on the wafer.

2. The photolithography mask according to claim 1, characterized in that: The closed figure is a square, the number of the closed areas is four, and the sides of the four closed areas are respectively parallel or perpendicular to the stepping direction.

3. The photolithography mask according to claim 1, characterized in that: The first graphic includes a first line segment pattern, a second line segment pattern and a third line segment pattern, the first line segment pattern and the second line segment pattern are parallel to each other and aligned end to end, and the third line segment pattern connects the midpoint of the first line segment pattern and the midpoint of the second line segment pattern; The second graphic includes a fourth line segment pattern, a fifth line segment pattern and a sixth line segment pattern, the fourth line segment pattern and the fifth line segment pattern are parallel to each other and aligned end to end, and the sixth line segment pattern connects the midpoint of the fourth line segment pattern and the midpoint of the fifth line segment pattern; The first line segment pattern and the fourth line segment pattern are perpendicular to each other.

4. The photolithography mask according to claim 3, characterized in that: A ratio of a distance between the first line segment pattern and the second line segment pattern to a length of the fourth line segment pattern is 70% to 95%; and / or, A ratio of a line width to a length of at least one of the first line segment pattern, the second line segment pattern, the third line segment pattern, the fourth line segment pattern, the fifth line segment pattern, and the sixth line segment pattern is 5% to 15%.

5. A photolithography alignment mark, characterized in that: including a first mark and a second mark; The first mark and the second mark are both open patterns, the first mark and the second mark are respectively formed by two adjacent exposures in step exposure, and the first mark and the second mark can be combined to form a lithography alignment mark including a closed pattern, the closed pattern includes at least three closed areas, and the centers of at least three of the closed areas are not collinear; The photolithography alignment mark is used to achieve alignment when the next photolithography process is performed on the wafer, and the number of pixels in at least three of the closed areas is used to determine the complementary value of the alignment.

6. The photolithography alignment mark according to claim 5, characterized in that: The closed figure is a square, the number of the closed areas is four, and the sides of the four closed areas are respectively parallel or perpendicular to the stepping direction.

7. The photolithography alignment mark according to claim 5, characterized in that: The first mark includes a first line segment portion, a second line segment portion and a third line segment portion, the first line segment portion and the second line segment portion are parallel to each other and aligned end to end, and the third line segment portion connects the midpoint of the first line segment portion and the midpoint of the second line segment portion; The second mark includes a fourth line segment portion, a fifth line segment portion and a sixth line segment portion, the fourth line segment portion and the fifth line segment portion are parallel to each other and aligned end to end, and the sixth line segment portion connects the midpoint of the fourth line segment portion and the midpoint of the fifth line segment portion; The first line segment portion and the fourth line segment portion are perpendicular to each other.

8. The photolithography alignment mark according to claim 7, characterized in that: A ratio of a distance between the first line segment portion and the second line segment portion to a length of the fourth line segment portion is 70% to 95%; and / or, A ratio of a line width to a length of at least one of the first line segment portion, the second line segment portion, the third line segment portion, the fourth line segment portion, the fifth line segment portion, and the sixth line segment portion is 5% to 15%.

9. A method for compensating exposure error in the same layer, characterized in that: The method comprises: Provide wafers; forming a first photoresist layer on the wafer; Performing a photolithography process using the photolithography mask as claimed in any one of claims 1 to 4 to form a plurality of exposure patterns in the photoresist layer, and forming a photolithography alignment mark in an overlapping area between an exposure pattern formed earlier and an exposure pattern formed later; transferring the photolithography alignment mark to the wafer; forming a second photoresist layer on the wafer; The photolithography process is performed again, and alignment is achieved based on the photolithography alignment mark, a complementary value for alignment is determined according to the number of pixel points of at least three of the closed areas within the photolithography alignment mark, and the alignment position is corrected according to the complementary value.

10. The method for compensating exposure error of the same layer according to claim 9, characterized in that: If the number of the enclosed regions within the photolithography alignment mark is less than three, feedback information is generated.

Images