A workpiece

Abstract

The application discloses a workpiece, and relates to the technical field of optics. In the application, the workpiece is a mask or a wafer, the workpiece has a functional area and an alignment area on a measurement plane, the alignment area is arranged around the functional area, the workpiece has a rotationally symmetric center, the alignment area has a plurality of alignment marks, one of any two alignment marks can be rotated around the rotationally symmetric center to a position coinciding with the other, and the alignment mark comprises two symmetrical sub-patterns and an asymmetrical sub-pattern arranged on the measurement plane. Each symmetrical sub-pattern has a first symmetry axis and a second symmetry axis perpendicular to each other. The asymmetrical sub-pattern is configured as a pattern asymmetric about the first symmetry axis and the second symmetry axis. The workpiece in the application has the alignment mark, so that a photolithography device can simultaneously realize direction identification and high-precision measurement, and the reliability of an alignment process is remarkably improved.

Description

Technical Field

[0001] This application relates to the field of optical technology, and in particular to a workpiece. Background Technology

[0002] In the semiconductor industry, etching is performed using photomasks. When aligning photomasks for measurement, symmetrical alignment marks can be used to compensate for common errors such as process variations through differential calculations, thereby achieving high-precision measurements at the nanometer level. However, the symmetrical design of the alignment marks also causes them to lose their orientation specificity. When a workpiece with alignment marks, such as a photomask or wafer, undergoes unexpected rotation or mirror flipping, such orientation errors cannot be identified from the symmetrical alignment marks during measurement, allowing the errors to hide in subsequent processes and ultimately leading to manufacturing failure. Summary of the Invention

[0003] To solve the above-mentioned technical problems, one technical solution adopted in this application is: providing a workpiece, which is a mask or wafer, having a functional area and an alignment area on a measurement plane. The alignment area is disposed around the functional area. The workpiece has a center of rotational symmetry, and the alignment area has multiple alignment marks. One of any two alignment marks can be rotated around the center of rotational symmetry to a position coinciding with the other. The alignment marks include two symmetrical sub-figures and one asymmetrical sub-figure arranged on the measurement plane. Each symmetrical sub-figure has a first axis of symmetry and a second axis of symmetry that are perpendicular to each other. The asymmetrical sub-figure is configured to be asymmetrical about the first axis of symmetry and the second axis of symmetry.

[0004] The beneficial effects of this application are as follows: Alignment marks are set within the alignment area of ​​the workpiece, and the photolithography equipment identifies the alignment mark signals to determine the position and orientation of the workpiece. The asymmetric sub-patterns in the alignment marks provide the photolithography equipment with an orientation reference that can be directly identified from the signal, thereby effectively detecting and preventing orientation errors caused by workpiece rotation or mirror flipping. Simultaneously, the two symmetric sub-patterns of the alignment marks allow the photolithography equipment to still operate based on the differential measurement principle, suppressing common noise and ensuring the position measurement accuracy of the workpiece. When multiple alignment marks are set on the workpiece in a specific layout, the photolithography equipment can simultaneously achieve workpiece orientation identification and high-precision position measurement, significantly improving the reliability of the alignment process. Attached Figure Description

[0005] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0006] Figure 1 This is a schematic diagram of the structure of a workpiece with alignment marks in some embodiments of this application; Figure 2 This is a schematic diagram of the structure of a workpiece with alignment marks in some embodiments of this application; Figure 3 This is a schematic diagram of the structure of a workpiece with alignment marks in some embodiments of this application; Figure 4 This is a schematic diagram of the structure of a workpiece with alignment marks in some embodiments of this application; Figure 5 This is a schematic diagram of the structure of another workpiece with alignment marks in some embodiments of this application; Figure 6 This is a schematic diagram of the structure of another workpiece with alignment marks in some embodiments of this application; Figure 7 This is a schematic diagram of the structure of a workpiece having another alignment mark in some embodiments of this application. Detailed Implementation

[0007] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0008] The terms "first" and "second" used in the embodiments of this application are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or devices.

[0009] This application describes a workpiece. The workpiece is a physical object used in photolithography processes and can be used to manufacture semiconductor devices such as integrated circuit chips, sensors, and power semiconductors. In some embodiments, the workpiece can be a photomask, which can be rectangular, such as a square or rectangle. In some embodiments, the workpiece can be a wafer, which can be circular. Of course, the workpiece can also be other shapes, which can be selected by those skilled in the art according to actual needs.

[0010] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0011] Please see Figure 1 , Figure 1 This is a schematic diagram of the structure of a workpiece 10 with alignment marks 13 in some embodiments of this application. The workpiece 10 may include a functional region 11 and an alignment region 12. The functional region 11 is typically located at the center of the workpiece 10 and is used to form or define a semiconductor structure with electrical functions. The alignment region 12 may be disposed around the functional region 11 and has graphics or structures for positioning, namely the alignment marks 13, to ensure the positional and directional accuracy of the workpiece 10 during processing.

[0012] In some embodiments, when the workpiece 10 is a photomask, its functional area 11 contains a main circuit pattern for defining an integrated circuit, which is projected onto the wafer surface by photolithography. The alignment area 12 of the photomask has alignment marks 13, which provide high-precision positioning and absolute orientation reference for the photomask itself in the photolithography equipment. In some embodiments, the alignment marks 13 may be a pattern or structure composed of scribing grooves.

[0013] In some embodiments, a photomask is a master template that carries a design pattern for a specific layer of an integrated circuit. The photomask is used for the permanent storage and transfer of graphic information. It has an opaque design pattern for a specific layer of circuitry. The photolithography equipment emits light through the transparent areas of the photomask, projecting the pattern onto the surface of a wafer coated with photoresist, thus completing the transfer of graphic information. In some embodiments, alignment marks 13 can be fabricated within the alignment area 12 of the photomask. When the photomask is loaded into the photolithography equipment, the equipment scans and identifies the alignment marks 13 on the photomask to determine its position and orientation. This alignment process ensures that the position and orientation of the photomask within the projection system of the photolithography equipment are accurate.

[0014] In some embodiments, the lithography equipment may employ a high-resolution imaging camera, a laser scanning interferometer, etc., to identify the alignment mark 13 and generate a corresponding data signal based on the alignment mark 13. The data signal is then compared with a preset data signal to confirm alignment.

[0015] In some embodiments, when the workpiece 10 is a wafer, its functional region 11 is composed of a plurality of repeating chip cells for building integrated circuits layer by layer. The alignment region 12 of the wafer may have a physical structure of alignment marks 13 copied from the mask for use by photolithography equipment to perform global wafer alignment and overlay alignment.

[0016] In some embodiments, alignment marks 13 may be fabricated within the alignment region 12 of the wafer. The photolithography equipment adjusts the mask position by scanning the existing alignment marks 13 formed by the previous process layer and measuring the deviation between the actual position of the alignment marks 13 and the theoretical position of the current layer pattern, ensuring accurate overlay of interlayer patterns. Alignment marks 13 can also be used to determine the position and orientation of the wafer and correct wafer loading deviations.

[0017] Workpiece 10 has a rotational symmetry center 111. The rotational symmetry center 111 is the geometric center point of workpiece 10. In some embodiments, the alignment region 12 may have multiple alignment marks 13, such as a first alignment mark 131 and a second alignment mark 132. The first alignment mark 131 can be rotated about the rotational symmetry center 111 of workpiece 10 to a position coinciding with the second alignment mark 132. Of course, the number of alignment marks 13 can also be three, four, or even more, and those skilled in the art can choose according to actual needs.

[0018] In some embodiments, among the plurality of alignment marks 13, one of any two alignment marks 13 can be rotated about the rotational symmetry center 111 to coincide with the other. When the plurality of alignment marks 13 have rotational symmetry about the rotational symmetry center 111 of the workpiece 10, a clear physical relationship is established between the plurality of alignment marks 13, which can improve the overall accuracy and reliability of alignment.

[0019] See again Figure 1In some applications, the workpiece 10 has two alignment marks 13, such as a first alignment mark 131 and a second alignment mark 132. The two alignment marks 13 are respectively located at the lower left and lower right corners of the alignment area 12 of the workpiece 10. For example, the first alignment mark 131 is located at the lower left corner of the alignment area 12, and the second alignment mark 132 is located at the lower right corner of the alignment area 12. The first alignment mark 131 rotates counterclockwise around the rotational symmetry center 111 of the workpiece 10 to the position of the second alignment mark 132, coinciding with the second alignment mark 132. In some embodiments, the first alignment mark 131 can be rotated 90 degrees counterclockwise around the rotational symmetry center 111 of the workpiece 10 to the position of the second alignment mark 132. Of course, other rotation angles can be adjusted according to requirements, which will not be elaborated further.

[0020] In some application scenarios, workpiece 10 is loaded into a photolithography machine. The machine can scan and identify alignment mark signals at the lower left and lower right corners of workpiece 10, allowing it to determine that workpiece 10 is correctly loaded. If workpiece 10 rotates 90 degrees counterclockwise around the rotational symmetry center 111 during loading, the machine can identify that the original second alignment mark 132 still has an alignment mark signal, but the original first alignment mark 131 does not. Instead, an alignment mark signal appears at the upper right corner of the alignment area 12. The machine can determine that workpiece 10 has undergone a counterclockwise rotation (e.g., a 90-degree rotation) loading error and can warn or correct this error to prevent further failures in subsequent processes. Of course, by setting the two alignment marks 13 at the lower left and lower right corners of the alignment area 12 of the workpiece 10, the photolithography equipment can also scan and identify that the workpiece 10 has rotated counterclockwise or clockwise around the rotation symmetry center 111, for example, by 180 degrees, 270 degrees or other angles, and this will not be elaborated here.

[0021] In some embodiments, the two alignment marks 13 may also be positioned in other locations, for example, the first alignment mark 131 may be positioned at the upper left corner of the alignment area 12, and the second alignment mark 132 may be positioned at the lower left corner of the alignment area 12 (e.g., ...). Figure 2 (As shown). The photolithography equipment can also identify whether the workpiece 10 has experienced a rotational loading error around the rotational symmetry center 111. Of course, those skilled in the art can choose according to actual needs.

[0022] In some embodiments, the first alignment mark 131 is located at the lower left corner of the alignment area 12, and the second alignment mark 132 is located at the upper right corner of the alignment area 12. In this case, the first alignment mark 131 can rotate 180 degrees counterclockwise around the rotational symmetry center 111 to reach the position of the second alignment mark 132, while the second alignment mark 132 rotates to the position of the first alignment mark 131. The lithography equipment cannot recognize this loading error. Therefore, alignment marks 13 can be added at other positions in the alignment area 12 to prevent this from happening. In some embodiments, three, four, or even more alignment marks 13 can also be provided to ensure alignment accuracy. Of course, those skilled in the art can choose according to actual needs.

[0023] See again Figure 1 The alignment mark 13 includes two symmetrical sub-patterns 102 and one asymmetrical sub-pattern 103 arranged on the measurement plane 101. The two symmetrical sub-patterns 102 and the one asymmetrical sub-pattern 103 work together for alignment in the semiconductor device fabrication process.

[0024] The first alignment mark 13 includes a first symmetrical sub-figure 1311, a second symmetrical sub-figure 1312, and an asymmetrical sub-figure 1313 arranged on the measurement plane 101. The first symmetrical sub-figure 1311 has a first axis of symmetry and a second axis of symmetry that are perpendicular to each other. The first axis of symmetry can refer to an axis in the measurement plane 101 that is parallel to the Y-axis of the rectangular coordinate system, and the second axis of symmetry can refer to an axis in the measurement plane 101 that is parallel to the X-axis of the rectangular coordinate system. The second symmetrical sub-figure 1312 also has a first axis of symmetry and a second axis of symmetry that are perpendicular to each other. The first axis of symmetry is parallel to the Y-axis of the rectangular coordinate system, and the second axis of symmetry is parallel to the X-axis of the rectangular coordinate system.

[0025] The symmetrical sub-figure 102 includes a side extending along the direction of the first axis of symmetry and a side extending along the direction of the second axis of symmetry. Within the measurement plane 101, since the first axis of symmetry and the second axis of symmetry are perpendicular to each other, the side extending along the direction of the first axis of symmetry and the side extending along the direction of the second axis of symmetry are also perpendicular to each other.

[0026] In some embodiments, the symmetrical sub-figure 102 is a square figure. The symmetrical sub-figure 102 has two sides extending along a first axis of symmetry and two sides extending along a second axis of symmetry, with the length and width of the sides extending along the first and second axes of symmetry being equal. These four sides form a square symmetrical sub-figure 102. In some embodiments, the symmetrical sub-figure 102 not only possesses symmetry about the first and second axes of symmetry but also rotational symmetry about its geometric center. That is, the symmetrical sub-figure 102 can still coincide with itself after rotating clockwise or counterclockwise around its geometric center, for example, by 90 degrees, 180 degrees, or 270 degrees.

[0027] In some embodiments, the widths of the two sides extending along the first axis of symmetry and the two sides extending along the second axis of symmetry of the symmetrical sub-figure 102 may not be equal, but their lengths are equal. In this case, the symmetrical sub-figure 102 is still axially symmetric about the first axis of symmetry and the second axis of symmetry.

[0028] In some embodiments, the symmetrical sub-figure 102 can also be designed as a cross-shaped structure, with two sides intersecting at their respective midpoints, one side extending along the direction of the first axis of symmetry and the other side extending along the direction of the second axis of symmetry. In some embodiments, the two sides of the cross-shaped symmetrical sub-figure 102 are perpendicular to each other, and the two sides have equal lengths and equal widths. In some embodiments, the two sides of the cross-shaped symmetrical sub-figure 102 are perpendicular to each other, and the two sides have unequal lengths but equal widths. In some embodiments, the two sides of the cross-shaped symmetrical sub-figure 102 are perpendicular to each other, and the two sides have equal lengths but unequal widths. In some embodiments, the symmetrical sub-figure 102 can be designed as a grid, circle, rounded rectangle, rhombus, or other shape that is symmetrical about the first and second axes of symmetry. In some embodiments, the symmetrical sub-figure 102 can be designed as a shape that combines any two, three, or more of the cross, grid, circle, rounded rectangle, rhombus, or other shapes, resulting in a shape that has symmetry including the first and second axes of symmetry. Of course, the symmetrical sub-figure 102 can also be designed as other figures that are symmetrical about both the first and second axes of symmetry. Those skilled in the art can choose according to actual needs.

[0029] In some embodiments, when a photolithography apparatus scans a symmetrical sub-pattern 102, such as a square, the reflected or diffracted light signals generated by the symmetrical sub-pattern 102 exhibit highly symmetrical and sharp characteristics due to the regularity of its edges. For example, this generates a pair of pulse signals with a spacing precisely equal to the width of the symmetrical sub-pattern 102, the spacing of which is determined by the physical dimensions of the symmetrical sub-pattern 102. This signal reflects the positional information of the symmetrical sub-pattern 102 in the measurement coordinate system, but it is also mixed with common process and system noise, such as signal disturbances caused by uneven photoresist thickness, illumination fluctuations, or wafer warping. When two identical symmetrical sub-patterns 102 are used, two pairs of signals can be obtained. Since these two patterns are spatially adjacent and structurally identical, the common noise they experience is highly similar. By performing differential operations on these two pairs of signals, the photolithography apparatus can effectively suppress the common noise, thereby significantly improving the quality and stability of the alignment signal. This allows the photolithography apparatus to clearly and reliably identify the positions of the two symmetrical sub-patterns 102, thus achieving high-precision alignment.

[0030] In some embodiments, the first symmetrical sub-figure 1311 and the second symmetrical sub-figure 1312 have the same shape and size. For example, the first symmetrical sub-figure 1311 and the second symmetrical sub-figure 1312 can be square figures. In some embodiments, the first symmetrical sub-figure 1311 and the second symmetrical sub-figure 1312 may also have different shapes and sizes, but both the first symmetrical sub-figure 1311 and the second symmetrical sub-figure 1312 have mutually perpendicular first and second axes of symmetry. For example, the first symmetrical sub-figure 1311 can be a square figure, and the second symmetrical sub-figure 1312 can be a rectangle figure. Of course, other figures with mutually perpendicular first and second axes of symmetry can also be used.

[0031] See again Figure 1 The asymmetric sub-figure 103 is asymmetric about the first axis of symmetry and the second axis of symmetry. In some embodiments, the asymmetric sub-figure 1313 is an L-shaped figure. The asymmetric sub-figure 1313 includes a side extending along the direction of the first axis of symmetry and a side extending along the direction of the second axis of symmetry. Since the first axis of symmetry and the second axis of symmetry are perpendicular to each other, the two sides of the asymmetric sub-figure 1313 are also perpendicular to each other. In some embodiments, the asymmetric sub-figure 1313 can be designed as an L-shaped figure with a side length ratio of 1:1. In some embodiments, the two sides of the asymmetric sub-figure 1313 can be eccentric trapezoids to enhance the sensitivity of the lithography equipment to identify the direction. In some embodiments, the asymmetric sub-figure 103 can also be an asymmetric figure about the first axis of symmetry and the second axis of symmetry formed by adding decorative graphic changes to an L-shaped figure, such as an arrow figure, a staircase figure, or an L-shaped figure with a thick square added to the vertex. In some embodiments, the asymmetric sub-figure 103 can also be an asymmetric figure about the first axis of symmetry and the second axis of symmetry generated by any two, three, or more combinations of figures such as an arrow figure, a staircase figure, or an L-shaped figure with a thick square added to the vertex. Of course, the asymmetric sub-graphic 103 can also be designed as other asymmetric graphics about the first axis of symmetry and the second axis of symmetry, and those skilled in the art can choose according to actual needs.

[0032] In some embodiments, the opening of the asymmetric sub-pattern 1313 is oriented toward the rotational symmetry center 111 of the workpiece 10, extending along the geometric center of the asymmetric sub-pattern 1313. After the asymmetric sub-pattern 1313 rotates about the rotational symmetry center 111 of the workpiece 10, the orientation of its opening changes. For example, after the asymmetric sub-pattern 1313 rotates 90 degrees counterclockwise about the rotational symmetry center 111 of the workpiece 10, the orientation of its opening also rotates 90 degrees counterclockwise.

[0033] In some application scenarios, when the asymmetric sub-pattern 1313 undergoes a rotational loading error around the rotational symmetry center 111 of the workpiece 10, the lithography equipment can detect significant changes in signal characteristics, thereby identifying the rotational loading error of the workpiece 10. In some application scenarios, if the workpiece 10 undergoes a flip loading error, the opening orientation of the asymmetric sub-pattern 1313 will also change after flipping, and the lithography equipment can also detect significant changes in signal characteristics, thereby identifying the flip loading error of the workpiece 10.

[0034] In some embodiments, the two symmetrical sub-patterns 102 of the alignment mark 13 are allowed to rotate to coincide around the rotational symmetry center 111 of the workpiece 10, but the asymmetrical sub-pattern 103 cannot coincide with itself after rotation, so that the lithography equipment can identify the rotation or mirror flip state of the workpiece 10 under various working conditions.

[0035] The lithography equipment measures the signals of the first symmetrical sub-pattern 1311 and the second symmetrical sub-pattern 1312 of the alignment mark 13, and uses differential operations to effectively suppress common process noise, achieving high-precision position measurement. The asymmetrical sub-pattern 1313 of the alignment mark 13 provides an absolute orientation reference for the lithography equipment, enabling it to directly identify and prevent rotational or mirror loading errors of the workpiece 10. The first symmetrical sub-pattern 1311, the second symmetrical sub-pattern 1312, and the asymmetrical sub-pattern 1313 work together, giving the alignment mark 13 the dual functions of orientation verification and precision measurement, effectively improving the reliability of lithography alignment.

[0036] In some embodiments, one of the two symmetrical sub-figures 102, such as the first symmetrical sub-figure 1311 and the asymmetrical sub-figure 1313, is arranged along a first axis of symmetry, while the other, such as the second symmetrical sub-figure 1312, is arranged along a second axis of symmetry. In some embodiments, the positions of the first symmetrical sub-figure 1311 and the asymmetrical sub-figure 1313 can be interchanged. In some embodiments, the positions of the second symmetrical sub-figure 1312 and the asymmetrical sub-figure 1313 can be interchanged. Of course, those skilled in the art can select the specific positions of the symmetrical sub-figures 102 and the asymmetrical sub-figures 103 according to actual needs.

[0037] In some embodiments, an additional symmetrical sub-figure 102, such as a first symmetrical sub-figure 1311, or an additional asymmetrical sub-figure 103 may be added to the alignment mark to enhance the orientation verification and precision measurement functions of the alignment mark 13. Of course, those skilled in the art can select the specific number of symmetrical sub-figures 102 and asymmetrical sub-figures 103 according to actual needs.

[0038] See again Figure 1The second alignment mark 132 includes a first symmetrical sub-figure 1321, a second symmetrical sub-figure 1322, and an asymmetrical sub-figure 1323 arranged on the measuring plane 101. In some embodiments, the second alignment mark 132 may be obtained by rotating the first alignment mark 131 counterclockwise by 90 degrees around the rotational symmetry center 111 of the workpiece 10, and the specific structure is the same as that of the first alignment mark 131, which will not be described in detail here.

[0039] In some embodiments, the plurality of alignment marks 13 include a first alignment mark 131 and a second alignment mark 132. The first alignment mark 131 is located at the lower left corner of the alignment area 12, and the second alignment mark 132 is located at the lower right corner of the alignment area 12. The two symmetrical sub-figures in the first alignment mark 131 and the two symmetrical sub-figures in the second alignment mark 132 are symmetrically arranged about a third axis of symmetry. In some embodiments, the third axis of symmetry refers to an axis in the measuring plane 101 that passes through the rotational symmetry center 111 of the workpiece 10 and is parallel to the Y-axis of the Cartesian coordinate system. Since the first axis of symmetry is parallel to the Y-axis of the Cartesian coordinate system of the measuring plane 101, the third axis of symmetry is also parallel to the first axis of symmetry.

[0040] Please see Figure 2 , Figure 2 This is a schematic diagram of the structure of a workpiece 20 with alignment marks 23 in some embodiments of this application. The workpiece 20 may include a functional region 21 and an alignment region 22. In some embodiments, the functional region 21 of the workpiece 20 has the same or similar structure as the functional region 11 of the workpiece 10, which will not be described in detail here. The alignment region 22 of the workpiece 20 has multiple alignment marks 23, such as a first alignment mark 231 and a second alignment mark 232. In some embodiments, the two alignment marks 23 in the workpiece 20 may be... Figure 1 The two alignment marks 13 of the workpiece 10 are obtained by rotating the two alignment marks 13 of the workpiece 10 clockwise by 90 degrees around the rotational symmetry center 111 of the workpiece 10.

[0041] The first alignment mark 231 is located at the upper left corner of the alignment area 12, and the second alignment mark 232 is located at the lower left corner of the alignment area 12. In some embodiments, the first alignment mark 231 can be rotated 90 degrees counterclockwise around the rotational symmetry center 211 of the workpiece 20 to a position coinciding with the second alignment mark 232. The two symmetrical sub-figures 102 in the first alignment mark 231 and the two symmetrical sub-figures 102 in the second alignment mark 232 are symmetrically arranged about a fourth axis of symmetry. In some embodiments, the fourth axis of symmetry refers to the axis in the measuring plane 101 that passes through the rotational symmetry center 211 of the workpiece 20 and is parallel to the X-axis of the Cartesian coordinate system. Since the second axis of symmetry is parallel to the X-axis of the Cartesian coordinate system of the measuring plane 101, the fourth axis of symmetry is also parallel to the second axis of symmetry.

[0042] Please see Figure 3 , Figure 3 This is a schematic diagram of the structure of a workpiece 30 with alignment marks 33 in some embodiments of this application. The workpiece 30 includes a functional region 31 and an alignment region 32. In some embodiments, the functional region 31 of the workpiece 30 has the same or similar structure as the functional region 11 of the workpiece 10, which will not be described in detail here. The alignment region 32 of the workpiece 30 has multiple alignment marks 33, such as a first alignment mark 331 and a second alignment mark 332. In some embodiments, the two alignment marks 33 in the workpiece 30 may be... Figure 1 The two alignment marks 13 of the workpiece 10 are obtained by rotating the two alignment marks 13 counterclockwise by 90 degrees around the rotational symmetry center 111 of the workpiece 10.

[0043] The first alignment mark 331 is located at the lower right corner of the alignment area 32, and the second alignment mark 332 is located at the upper right corner of the alignment area 32. In some embodiments, the first alignment mark 331 can be rotated 90 degrees counterclockwise around the rotational symmetry center 311 of the workpiece 30 until it coincides with the second alignment mark 332. The two symmetrical sub-figures 102 in the first alignment mark 331 and the two symmetrical sub-figures 102 in the second alignment mark 332 are symmetrical about a fourth axis of symmetry.

[0044] Please see Figure 4 , Figure 4 This is a schematic diagram of the structure of a workpiece 40 with alignment marks 43 in some embodiments of this application. The workpiece 40 includes a functional region 41 and an alignment region 42. In some embodiments, the functional region 41 of the workpiece 40 has the same or similar structure as the functional region 11 of the workpiece 10, which will not be described in detail here. The alignment region 42 of the workpiece 40 has multiple alignment marks 43, such as a first alignment mark 431 and a second alignment mark 432. In some embodiments, the two alignment marks 43 in the workpiece 40 may be derived from... Figure 1 The two alignment marks 13 of the workpiece 10 are obtained by rotating the two alignment marks 13 of the workpiece 10 by 180 degrees clockwise or counterclockwise around the rotational symmetry center 111 of the workpiece 10.

[0045] The first alignment mark 431 is located at the upper right corner of the alignment area 43, and the second alignment mark 432 is located at the upper left corner of the alignment area 43. In some embodiments, the first alignment mark 431 can be rotated 90 degrees counterclockwise around the rotational symmetry center 411 of the workpiece 40 to a position coinciding with the second alignment mark 432. The two symmetrical sub-figures 102 in the first alignment mark 431 and the two symmetrical sub-figures 102 in the second alignment mark 432 are symmetrically arranged about a third axis of symmetry. In some embodiments, the third axis of symmetry refers to the axis in the measuring plane 101 that passes through the rotational symmetry center 411 of the workpiece 40 and is parallel to the Y-axis of the Cartesian coordinate system. Since the first axis of symmetry is parallel to the Y-axis of the Cartesian coordinate system of the measuring plane 101, the third axis of symmetry is also parallel to the first axis of symmetry.

[0046] Please see Figure 5 , Figure 5 This is a schematic diagram of the structure of another workpiece 50 with alignment marks 53 in some embodiments of this application. The workpiece 50 includes a functional region 51 and an alignment region 52. The alignment region 52 has multiple alignment marks 53, such as a first alignment mark 531, a second alignment mark 532, and a third alignment mark 533.

[0047] In some embodiments, the functional region 51 of the workpiece 50 has the same or similar structure as the functional region 11 of the workpiece 10, and will not be described in detail here. The alignment mark 53 provided on the workpiece 50 has the same or similar structure as the alignment mark 13 provided on the workpiece 10, and will not be described in detail here.

[0048] In some embodiments, a first alignment mark 531 is located at the lower left corner of the alignment region 52, a second alignment mark 532 is located at the lower right corner of the alignment region 52, and a third alignment mark 533 is located at the upper left corner of the alignment region 52. The two symmetrical sub-figures 102 in the first alignment mark 531 and the two symmetrical sub-figures 102 in the second alignment mark 532 are symmetrical about a third axis of symmetry, and the two symmetrical sub-figures 102 in the first alignment mark 531 and the two symmetrical sub-figures 102 in the third alignment mark 533 are symmetrical about a fourth axis of symmetry.

[0049] In some embodiments, the first alignment mark 531 may be rotated 90 degrees counterclockwise about the rotational symmetry center 511 of the workpiece 50 to a position coinciding with the second alignment mark 532. In some embodiments, the first alignment mark 531 may be rotated 90 degrees clockwise about the rotational symmetry center 511 of the workpiece 50 to a position coinciding with the third alignment mark 533.

[0050] In some applications, the lithography equipment can scan and identify the positions of each alignment mark 53 to detect whether the workpiece 50 is correctly positioned and oriented. When the workpiece 50 rotates around the rotational symmetry center 211, for example, 90 degrees counterclockwise, the alignment mark signal that should not have been detected at the upper right corner of the workpiece 50 may still be detected by the lithography equipment. Conversely, if the alignment mark signal that should have been detected at the upper left corner of the workpiece 50 is not detected, the lithography equipment can determine that a rotational loading error has occurred. When the workpiece 50 is mirror-flipped, the opening orientation of the asymmetric sub-pattern 103 in the alignment mark 53 changes, and the lithography equipment can determine that a flip loading error has occurred. Because the alignment area 52 increases the number of alignment marks 53, the lithography equipment can scan and identify more alignment mark signals, thereby enhancing its ability to identify flip or rotation loading errors and improving alignment accuracy and reliability.

[0051] Please see Figure 6 , Figure 6 This is a schematic diagram of the structure of another workpiece 60 with alignment marks 63 in some embodiments of this application. The workpiece 60 includes a functional region 61 and an alignment region 62. The alignment region 62 has multiple alignment marks 63, such as a first alignment mark 631, a second alignment mark 632, a third alignment mark 633, and a fourth alignment mark 634.

[0052] In some embodiments, the functional region 61 of the workpiece 60 has the same or similar structure as the functional region 11 of the workpiece 10, and will not be described in detail here. The alignment mark 63 provided on the workpiece 60 has the same or similar structure as the alignment mark 11 provided on the workpiece 10, and will not be described in detail here.

[0053] The first alignment mark 631 is located at the lower left corner of the alignment area 62, the second alignment mark 632 is located at the lower right corner of the alignment area 62, the third alignment mark 633 is located at the upper right corner of the alignment area 62, and the fourth alignment mark 634 is located at the upper left corner of the alignment area 62. The two symmetrical sub-figures 102 in the fourth alignment mark 634 and the two symmetrical sub-figures 102 in the third alignment mark 633 are symmetrical about the third axis of symmetry. The two symmetrical sub-figures 102 in the fourth alignment mark 634 and the two symmetrical sub-figures 102 in the first alignment mark 631 are symmetrical about the fourth axis of symmetry. The two symmetrical sub-figures 102 in the first alignment mark 631 and the two symmetrical sub-figures 102 in the second alignment mark 632 are symmetrical about the third axis of symmetry. The two symmetrical sub-figures 102 in the third alignment mark 633 and the two symmetrical sub-figures 102 in the second alignment mark 632 are symmetrical about the fourth axis of symmetry.

[0054] In some use cases, such as Figure 6The alignment marks 63 arranged at the indicated positions will coincide with themselves after being rotated 90 degrees, 180 degrees, or 270 degrees counterclockwise or clockwise around the rotational symmetry center 611 of the workpiece 60, allowing for single-plate overlay. Using a workpiece 60, such as a mask, with four alignment marks 63, exposure is performed on a wafer to form a first set of patterns. Then, the wafer is rotated by a predetermined angle, such as 180 degrees, and the same workpiece 60, such as a mask, is used again at the same position to form a second set of patterns. Due to the rotational symmetry of the workpiece 60 with four alignment marks 63, the two sets of patterns should ideally coincide perfectly. By measuring the actual offset between the two sets of patterns with high precision, the systematic error of the lithography equipment between the two exposures can be calculated, thereby achieving overlay calibration.

[0055] Please see Figure 7 , Figure 6 This is a schematic diagram of the structure of a workpiece 70 having another alignment mark 73 in some embodiments of this application. The workpiece 70 includes a functional region 71 and an alignment region 72. The alignment region 72 has multiple alignment marks 73, such as a first alignment mark 731 and a second alignment mark 732.

[0056] In some embodiments, the functional region 71 of the workpiece 70 has the same or similar structure as the functional region 11 of the workpiece 10, which will not be described in detail here.

[0057] In some embodiments, the symmetrical sub-figures 102 in the alignment mark 73 may have a rectangular structure. The first alignment mark 731 may consist of two rectangular symmetrical sub-figures 102, such as a first symmetrical sub-figure 7311 and a second symmetrical sub-figure 7312 and an asymmetrical sub-figure 7313.

[0058] The symmetrical subfigure 102 has two sides extending along a first axis of symmetry and two sides extending along a second axis of symmetry. The two sides extending along the first axis of symmetry are of equal length, and the two sides extending along the second axis of symmetry are of equal length, but the lengths of the two sets of sides are not equal. These four sides thus form a rectangular symmetrical subfigure 102. In some embodiments, the symmetrical subfigure 102, for example, the first symmetrical subfigure 7311 and the second symmetrical subfigure 7312, has symmetry about the first axis of symmetry and the second axis of symmetry.

[0059] In some embodiments, the width of the side extending along the first axis of symmetry of the symmetrical sub-figure 102 may be equal to or unequal to the width of the side extending along the second axis of symmetry, as long as the symmetrical sub-figure 102 is axially symmetric about the mutually perpendicular first and second axes of symmetry. Those skilled in the art can make the selection according to actual needs.

[0060] In some embodiments, asymmetric subgraph 7313 and Figure 1 The asymmetric subgraphs 1313 in the text have similar or identical structures, which will not be elaborated here.

[0061] In some embodiments, the first alignment mark 731 may be rotated 90 degrees counterclockwise around the rotational symmetry center 711 of the workpiece 70 to coincide with the second alignment mark 732.

[0062] This application sets alignment marks within the alignment area of ​​the workpiece. The photolithography equipment identifies the alignment mark signals to determine the workpiece's position and orientation. The asymmetric sub-patterns in the alignment marks provide the photolithography equipment with an orientation reference that can be directly identified from the signals, thereby effectively detecting and preventing orientation errors caused by workpiece rotation or mirror flipping. Simultaneously, the two symmetric sub-patterns of the alignment marks allow the photolithography equipment to still operate based on the differential measurement principle, suppressing common noise and ensuring the workpiece's position measurement accuracy. When multiple alignment marks are arranged in a specific layout on the workpiece, the photolithography equipment can simultaneously achieve workpiece orientation identification and high-precision position measurement, significantly improving the reliability of the alignment process.

[0063] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A workpiece, characterized in that, The workpiece is a mask or a wafer. The workpiece has a functional area and an alignment area on the measurement plane. The alignment area is arranged around the functional area. The workpiece has a rotational symmetry center. The alignment area has multiple alignment marks. Any two alignment marks can be rotated around the rotational symmetry center to coincide with the other. The alignment marks include two symmetrical sub-figures and one asymmetrical sub-figure arranged on the measurement plane. Each of the symmetrical sub-figures has a first axis of symmetry and a second axis of symmetry that are perpendicular to each other; The asymmetric subgraph is configured as a graph that is asymmetric about the first axis of symmetry and the second axis of symmetry.

2. The workpiece according to claim 1, characterized in that, The symmetrical sub-figure includes an edge extending along the first axis of symmetry and an edge extending along the second axis of symmetry.

3. The workpiece according to claim 2, characterized in that, The symmetrical sub-figure is a square figure.

4. The workpiece according to claim 1, characterized in that, The asymmetric sub-graph includes an edge extending along the first axis of symmetry and an edge extending along the second axis of symmetry.

5. The workpiece according to claim 4, characterized in that, The asymmetric sub-figure is an "L" shaped figure.

6. The workpiece according to claim 1, characterized in that, The plurality of alignment marks include a first alignment mark and a second alignment mark. The two symmetrical sub-figures in the first alignment mark and the two symmetrical sub-figures in the second alignment mark are symmetrically arranged about a third axis of symmetry or a fourth axis of symmetry. The third axis of symmetry is parallel to the first axis of symmetry, and the fourth axis of symmetry is parallel to the second axis of symmetry.

7. The workpiece according to claim 6, characterized in that, The plurality of alignment marks includes a third alignment mark, wherein the two symmetrical sub-figures in the first alignment mark and the two symmetrical sub-figures in the second alignment mark are symmetrically arranged about the third axis of symmetry, and the two symmetrical sub-figures in the first alignment mark and the two symmetrical sub-figures in the third alignment mark are symmetrically arranged about the fourth axis of symmetry.

8. The workpiece according to claim 7, characterized in that, The plurality of alignment marks includes a fourth alignment mark, wherein the two symmetrical sub-figures in the fourth alignment mark and the two symmetrical sub-figures in the third alignment mark are symmetrically arranged about the third axis of symmetry, and the two symmetrical sub-figures in the fourth alignment mark and the two symmetrical sub-figures in the first alignment mark are symmetrically arranged about the fourth axis of symmetry.

9. The workpiece according to claim 1, characterized in that, One of the two symmetrical sub-figures and the asymmetrical sub-figure are arranged along the first axis of symmetry, and the other is arranged along the second axis of symmetry with the asymmetrical sub-figure.

10. The workpiece according to claim 1, characterized in that, The workpiece is square.

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