Alignment mark, formation method thereof and mask layout

Abstract

The invention discloses an alignment mark, a forming method thereof and a mask layout, and the alignment mark comprises a substrate which comprises a measurement area; the dielectric layer is located at the top of the substrate, and a detection opening located in the measurement area is formed in the dielectric layer; the first measurement identifier is located in the dielectric layer, and the top surface of the first measurement identifier located in the measurement region is exposed by the detection opening; and the second measurement identifier is located in the dielectric layer and is staggered from the first measurement identifier, the extension direction of the second measurement identifier is the same as the extension direction of the first measurement identifier, and the top surface of the second measurement identifier is higher than the top surface of the first measurement identifier. The detection opening exposes the top surface of the first measurement identifier, and the boundary of the first measurement identifier can be clearly visible in the process of scanning and measuring the first measurement identifier, so that the measurement accuracy of the first measurement identifier is improved, and the measurement accuracy of the second measurement identifier is improved after the second measurement identifier is measured. Therefore, the accuracy of the overlay error value between the first measurement identifier and the second measurement identifier can be improved.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of semiconductor manufacturing, and in particular to an alignment mark and a method for forming the alignment mark and a mask pattern. Background Art

[0002] With the continuous advancement of technology nodes, the overlay error is getting smaller and smaller. The overlay error measurement (OVL) after photolithography development (ADI) uses a diffraction-based overlay mark (DBO mark). Affected by the etching process, the OVL value of the same measurement point from after development (ADI) to after etching (AEI) will have a fixed difference (AEI_ADI offset). In order to obtain a fixed difference to correct ADI, it is necessary to design a post-etching measurement mark to obtain OVL. Summary of the invention

[0003] The problem solved by the embodiments of the present invention is to provide an alignment mark and a method for forming the alignment mark and a mask pattern, so as to improve the accuracy of overlay error measurement.

[0004] To solve the above problems, an embodiment of the present invention provides an alignment mark, including: a substrate, including a measurement area; a dielectric layer, located on the top of the substrate, and having a detection opening located in the measurement area in the dielectric layer; a first measurement mark, located in the dielectric layer, and the top surface of the first measurement mark located in the measurement area is exposed by the detection opening; a second measurement mark, located in the dielectric layer and staggered with the first measurement mark, the extension direction of the second measurement mark is the same as the extension direction of the first measurement mark, and the top surface of the second measurement mark is higher than the top surface of the first measurement mark.

[0005] Optionally, the area where the first measurement mark is located is the first identification area, and the area where the second measurement mark is located is the second identification area, and along the extension direction of the first measurement mark, the second identification area is entirely located on the side of the first identification area.

[0006] Optionally, the area where the first measurement mark is located is the first identification area, and the area where the second measurement mark is located is the second identification area, the center point of the first identification area, the center point of the second identification area, and the center point of the detection opening are all located on the same vertical line, and the extension direction of the vertical line is the same as the extension direction of the first measurement mark.

[0007] Optionally, with the direction perpendicular to the extension direction of the first measurement mark as the lateral direction, the lateral dimension of the detection opening and the pitch of adjacent first measurement marks satisfy the relationship: D=2n*P; wherein D represents the lateral dimension of the detection opening; P represents the pitch of adjacent first measurement marks; and n represents a positive integer.

[0008] Optionally, the first measurement mark and the second measurement mark with the same extension direction constitute a measurement mark group, and the measurement mark group includes one or both of an X-direction mark group and a Y-direction mark group, and the X direction is perpendicular to the Y direction; wherein the first measurement mark and the second measurement mark in the X-direction mark group both extend along the Y direction, and the first measurement mark and the second measurement mark in the Y-direction mark group both extend along the X direction.

[0009] Optionally, the first measurement mark is an integrated structure, and the second measurement mark is an integrated structure; or, in the extension direction of the first measurement mark, the first measurement mark includes a plurality of first sub-measurement marks arranged at intervals; in the extension direction of the second measurement mark, the second measurement mark includes a plurality of second sub-measurement marks arranged at intervals.

[0010] Optionally, the integrated structure includes a bar structure; the first sub-measurement mark includes a hole-type structure, and the second sub-measurement mark includes a hole-type structure.

[0011] Optionally, in the extension direction of the first sub-measurement mark and the second sub-measurement mark, the distance between adjacent first sub-measurement marks is 1 nanometer to 200 nanometers, and the distance between adjacent second sub-measurement marks is 1 nanometer to 200 nanometers.

[0012] Optionally, the material of the dielectric layer includes one or more of silicon oxide, silicon nitride and silicon oxynitride.

[0013] Correspondingly, an embodiment of the present invention further provides a mask pattern suitable for forming the alignment mark provided by the embodiment of the present invention, the mask pattern comprising: a first pattern layer, comprising a detection opening pattern, wherein the detection opening pattern is used to form a detection opening in a dielectric layer; a second pattern layer, located below the first pattern layer, wherein the second pattern layer comprises a first measurement identification pattern, and after the second pattern layer overlaps with the first pattern layer, the detection opening pattern has an overlapping portion with the first measurement identification pattern; a third pattern layer, located between the second pattern layer and the first pattern layer, wherein the third pattern layer comprises a second measurement identification pattern, and after the third pattern layer overlaps with the second pattern layer, the second measurement identification pattern is staggered with the first measurement identification pattern, and an extension direction of the second measurement identification pattern is the same as an extension direction of the first measurement identification pattern.

[0014] Optionally, the area where the first measurement identification graphic is located is the first identification area, and the area where the second measurement identification graphic is located is the second identification area. After the second layer and the first layer overlap, along the extension direction of the first measurement identification graphic, the second identification area is located as a whole on the side of the first identification area.

[0015] Optionally, the area where the first measurement identification graphic is located is the first identification area, and the area where the second measurement identification graphic is located is the second identification area. After the first layer, the second layer and the third layer overlap, the center point of the first identification area, the center point of the second identification area, and the center point of the detection opening graphic are all located on the same vertical line, and the extension direction of the vertical line is the same as the extension direction of the first measurement identification graphic.

[0016] Optionally, taking the direction perpendicular to the extension direction of the first measurement mark pattern as the lateral direction, the lateral size of the detection opening pattern and the pitch of the adjacent first measurement mark pattern need to satisfy the relationship: D=2n*P; wherein D represents the lateral size of the detection opening pattern; P represents the pitch of the adjacent first measurement mark patterns; and n represents a positive integer.

[0017] Optionally, after the third layer overlaps with the second layer, the first measurement identification graphic and the second measurement identification graphic having the same extension direction constitute a measurement identification group graphic, and the measurement identification group graphic includes one or both of an X-direction identification group graphic and a Y-direction identification group graphic, and the X direction is perpendicular to the Y direction; wherein the first measurement identification graphic and the second measurement identification graphic in the X-direction identification group graphic both extend along the Y direction, and the first measurement identification graphic and the second measurement identification graphic in the Y-direction identification group graphic both extend along the X direction.

[0018] Optionally, the first measurement identification graphic is an integrated structural graphic, and the second measurement identification graphic is an integrated structural graphic; or, in the extension direction of the first measurement identification graphic, the first measurement identification graphic includes a plurality of first sub-measurement identification graphics arranged at intervals; in the extension direction of the second measurement identification graphic, the second measurement identification graphic includes a plurality of second sub-measurement identification graphics arranged at intervals.

[0019] Optionally, the integrated structural pattern includes a bar-shaped structural pattern; the first sub-measurement identification pattern includes a hole-shaped structural pattern, and the second sub-measurement identification pattern includes a hole-shaped structural pattern.

[0020] Optionally, in the extension direction of the first sub-measurement identification pattern and the second sub-measurement identification pattern, the distance between adjacent first sub-measurement identification patterns is 1 nanometer to 200 nanometers, and the distance between adjacent second sub-measurement identification patterns is 1 nanometer to 200 nanometers.

[0021] Correspondingly, an embodiment of the present invention also provides a method for forming an alignment mark, comprising: providing a substrate, the substrate comprising a measurement area; forming a dielectric layer on the substrate, and a first measurement mark and a second measurement mark located in the dielectric layer, the second measurement mark being staggered with the first measurement mark, the extension direction of the second measurement mark being the same as the extension direction of the first measurement mark, and the top surface of the second measurement mark being higher than the top surface of the first measurement mark; and forming a detection opening in the dielectric layer in the measurement area, the detection opening exposing the top surface of the first measurement mark.

[0022] Optionally, the steps of forming a dielectric layer on the substrate, and a first measurement mark and a second measurement mark located in the dielectric layer include: forming a first measurement mark on the substrate; forming a dielectric layer covering the first measurement mark on the substrate; and performing graphing on the dielectric layer to form a second measurement mark in the dielectric layer.

[0023] Optionally, the step of forming a detection opening in the dielectric layer of the measurement area includes: forming a mask layer having a mask opening on the top of the dielectric layer of the measurement area, wherein the mask opening is located above the first measurement mark and exposes the dielectric layer above the first measurement mark; using the mask layer as a mask, performing a patterning process on the dielectric layer exposed by the mask opening, thereby forming a detection opening in the dielectric layer of the measurement area.

[0024] Compared with the prior art, the technical solution of the embodiment of the present invention has the following advantages:

[0025] In the alignment mark provided by the embodiment of the present invention, the dielectric layer is located on the top of the substrate, the dielectric layer has a detection opening located in the measurement area, the first measurement mark is located in the dielectric layer, and the top surface of the first measurement mark located in the measurement area is exposed by the detection opening, the second measurement mark is located in the dielectric layer and is staggered with the first measurement mark, the extension direction of the second measurement mark is the same as the extension direction of the first measurement mark, and the top surface of the second measurement mark is higher than the top surface of the first measurement mark. Since the detection opening exposes the top surface of the first measurement mark, the boundary of the first measurement mark can be clearly visible during the scanning and measurement of the first measurement mark, thereby improving the accuracy of measuring the first measurement mark, and after measuring the second measurement mark, the accuracy of the overlay error value between the first measurement mark and the second measurement mark can also be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 to Figure 2 is a schematic structural diagram of an embodiment of an alignment mark of the present invention;

[0027] Figures 3 to 10is a schematic structural diagram of an embodiment of an alignment mark of the present invention;

[0028] Figure 3 as well as Figures 6 to 10 The mask of the present invention Figure 1 A schematic diagram of an embodiment;

[0029] Figures 11 to 15 It is a schematic structural diagram corresponding to each step in an embodiment of a method for forming an alignment mark of the present invention. DETAILED DESCRIPTION

[0030] At present, the accuracy of overlay error measurement still needs to be improved. The reasons why its performance needs to be improved are analyzed in combination with an alignment mark.

[0031] Figure 1 to Figure 2 is a schematic diagram of the structure corresponding to the alignment mark, wherein: Figure 1 is a top view of the alignment mark, Figure 2 yes Figure 1 Cross-sectional view along the AA direction.

[0032] refer to Figure 1 to Figure 2 The alignment mark includes: a substrate 15 including a measurement area; a dielectric layer 10 located on the top of the substrate 15; a first measurement mark 11 located in the dielectric layer 10 in the measurement area, and the dielectric layer 10 covers the top surface of the first measurement mark 11; a second measurement mark 12 located in the dielectric layer 10 in the measurement area and staggered with the first measurement mark 11, the extension direction of the second measurement mark 12 is the same as the extension direction of the first measurement mark 11, the dielectric layer 10 exposes the top surface of the second measurement mark 12, and the top surface of the second measurement mark 12 is higher than the top surface of the first measurement mark 11.

[0033] Through research, it is found that in order to obtain the overlay error value between the first measurement mark 11 and the second measurement mark 12, the measurement equipment needs to identify and measure the boundary of the first measurement mark 11 and the boundary of the second measurement mark 12 respectively. Since the dielectric layer 10 covers the top surface of the first measurement mark 11, the measurement machine needs to use high voltage and large beam current signals to pass through the dielectric layer 10 on the top of the first measurement mark 11. The signal is easily scattered in the dielectric layer 10, which causes the boundary of the first measurement mark 11 identified by the measurement machine to be blurred, which means that the accuracy of the boundary coordinates of the first measurement mark 11 obtained is reduced, which in turn causes the accuracy of the obtained overlay error value to be reduced.

[0034] In order to solve the technical problem, an embodiment of the present invention provides an alignment mark, including: a substrate, including a measurement area; a dielectric layer, located on the top of the substrate, and having a detection opening located in the measurement area in the dielectric layer; a first measurement mark, located in the dielectric layer, and the top surface of the first measurement mark located in the measurement area is exposed by the detection opening; a second measurement mark, located in the dielectric layer and staggered with the first measurement mark, the extension direction of the second measurement mark is the same as the extension direction of the first measurement mark, and the top surface of the second measurement mark is higher than the top surface of the first measurement mark.

[0035] The alignment mark provided in the embodiment of the present invention has a detection opening that exposes the top surface of the first measurement mark. During the process of scanning and measuring the first measurement mark, the boundary of the first measurement mark can be clearly visible, thereby improving the accuracy of measuring the first measurement mark. After measuring the second measurement mark, the accuracy of the overlay error value between the first measurement mark and the second measurement mark can also be improved.

[0036] In order to make the above-mentioned purposes, features and advantages of the embodiments of the present invention more obvious and understandable, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0037] Figures 3 to 10 It is a structural schematic diagram corresponding to an embodiment of an alignment mark of the present invention. Figure 4 yes Figure 3 Cross-sectional view along BB direction, Figure 5 yes Figure 3 Cross-sectional view along the AA direction.

[0038] The alignment mark includes: a substrate 120, including a measurement area 100A; a dielectric layer 102, located on the top of the substrate 120, and having a detection opening 108 located in the measurement area 100A; a first measurement mark 105, located in the dielectric layer 102, and the top surface of the first measurement mark 105 located in the measurement area 100A is exposed by the detection opening 108; a second measurement mark 101, located in the dielectric layer 102 and staggered with the first measurement mark 105, the extension direction of the second measurement mark 101 is the same as the extension direction of the first measurement mark 105, and the top surface of the second measurement mark 101 is higher than the top surface of the first measurement mark 105.

[0039] It should be noted that since the detection opening 108 exposes the top surface of the first measurement mark 105, during the process of scanning and measuring the first measurement mark 105, the boundary of the first measurement mark 105 can be clearly visible, thereby improving the accuracy of measuring the first measurement mark 105. After measuring the second measurement mark 101, the accuracy of the overlay error value between the first measurement mark 105 and the second measurement mark 101 can also be improved.

[0040] The substrate 120 provides a process platform for setting alignment marks.

[0041] It should be noted that with the continuous advancement of technology nodes, the overlay error is getting smaller and smaller. The overlay error measurement (OVL) after lithography development (ADI) uses a diffraction-based overlay mark (DBO mark). Affected by the etching process, the OVL value of the same measurement point from after development (ADI) to after etching (AEI) will have a fixed difference (AEI_ADI offset). In order to obtain a fixed difference to correct ADI, it is necessary to design a post-etching measurement mark to obtain OVL.

[0042] The measurement area 100A is used to set a measurement mark, and the overlay error value is calculated by measuring the measurement mark.

[0043] The dielectric layer 102 provides a process basis for setting the first measurement mark 105 and the second measurement mark 101 .

[0044] It should be noted that, by providing a detection opening 108 located in the measurement area 100A in the dielectric layer 102, the detection opening 108 can expose the top surface of the first measurement mark 105. During the process of scanning and measuring the first measurement mark 105, the boundary of the first measurement mark 105 can be clearly visible, thereby improving the accuracy of measuring the first measurement mark 105. At the same time, during the process of scanning and measuring the first measurement mark 105, it is only necessary to provide a low voltage to the measuring machine to achieve a clear visibility of the boundary of the first measurement mark 105, thereby extending the service life of the measuring machine.

[0045] In this embodiment, the material of the dielectric layer 102 includes one or more of silicon oxide, silicon nitride and silicon oxynitride.

[0046] As an example, the first measurement mark 105 is located in the dielectric layer 102 and is covered by the dielectric layer 102 . Specifically, the first measurement mark 105 is a front layer mark.

[0047] The top surface of the first measurement mark 105 of the measurement area 100A is exposed by the detection opening 108, so that the measurement machine can accurately identify the boundary of the first measurement mark 105 and perform measurement without passing through the dielectric layer 102 to identify the boundary of the first measurement mark 105, thereby improving the accuracy of obtaining the overlay error value.

[0048] As an example, taking the direction perpendicular to the extension direction of the first measurement mark 105 as the lateral direction, the lateral dimension of the detection opening 108 and the pitch of adjacent first measurement marks 105 satisfy the relationship: D=2n*P; wherein D represents the lateral dimension of the detection opening 108; P represents the pitch of adjacent first measurement marks 105; and n represents a positive integer.

[0049] By making the lateral dimension of the detection opening 108 an integer multiple of the pitch of the adjacent first measurement marks 105, it is possible to ensure that the boundary of the detection opening 108 is exactly in the middle of the dielectric layer 102. Accordingly, during the measurement of the first measurement mark 105, the boundary of the first measurement mark 105 can be completely identified, and the first measurement mark 105 covered by the dielectric layer 102 will not be exposed, thereby maximizing the window size of the detection opening 108.

[0050] As an example, the second measurement mark 101 is located in the dielectric layer 102 and is staggered with the first measurement mark 105. Specifically, the second measurement mark 101 and the first measurement mark 105 are staggered, and an overlay error between the second measurement mark 101 and the first measurement mark 105 can be obtained.

[0051] In this embodiment, the top surface of the second measurement mark 101 is higher than the top surface of the first measurement mark 105, which means that there is a height difference between the first measurement mark 105 and the second measurement mark 101. The ADI is corrected by obtaining the overlay error of the measurement mark with the height difference.

[0052] As an example, the second measurement identifier 101 is a current layer identifier.

[0053] It should be noted that the second measurement mark 101 is located in the dielectric layer 102 and the top surface of the second measurement mark 101 is exposed by the dielectric layer 102. Since the top surface of the second measurement mark 101 is exposed by the dielectric layer 102, the measuring machine can accurately identify the boundary of the second measurement mark 101 and perform measurement, thereby improving the accuracy of obtaining the overlay error value.

[0054] In this embodiment, the area where the first measurement mark 105 is located is the first identification area (not marked), and the area where the second measurement mark 101 is located is the second identification area (not marked). Along the extension direction of the first measurement mark 105, the second identification area is located as a whole on the side of the first identification area.

[0055] Specifically, the second identification area is located as a whole on the side of the first identification area. In the process of setting the first measurement mark 105 and the second measurement mark 101, the first measurement mark 105 and the second measurement mark 101 can be made not to interfere with each other, which means that the size and pitch of the first measurement mark 105 and the size and pitch of the second measurement mark 101 can be freely and flexibly selected, and the probability of overlap between the first measurement mark 105 and the second measurement mark 101 is reduced, so that the overlay error value can be further accurately obtained.

[0056] In this embodiment, the area where the first measurement mark 105 is located is the first identification area, and the area where the second measurement mark 101 is located is the second identification area. The center point of the first identification area, the center point of the second identification area, and the center point of the detection opening 108 are all located on the same vertical line, and the extension direction of the vertical line is the same as the extension direction of the first measurement mark 105, which is conducive to obtaining the overlay error value of the measurement mark with a height difference.

[0057] refer to Figures 6 to 8 , the first measurement mark 105 and the second measurement mark 101 extending in the same direction constitute a measurement mark group (not marked), and the measurement mark group includes one or both of an X-direction mark group and a Y-direction mark group, and the X direction is perpendicular to the Y direction, wherein the first measurement mark 105 and the second measurement mark 101 in the X-direction mark group both extend along the Y direction, and the first measurement mark 105 and the second measurement mark 101 in the Y-direction mark group both extend along the X direction.

[0058] It should be noted that the X-direction mark group is used to measure the overlay error value in the X direction, and the Y-direction mark group is used to measure the overlay error value in the Y direction.

[0059] It should also be noted that, when the measurement mark group includes an X-direction mark group and a Y-direction mark group, the top surfaces of the first measurement marks 105 of the X-direction mark group and the Y-direction mark group are respectively exposed by corresponding detection openings 108, so that the measurement machine can measure the boundary of the first measurement mark 105 in the X-direction mark group and the boundary of the first measurement mark 105 in the Y-direction mark group through the corresponding detection openings 108, respectively.

[0060] like Fig. 9 As shown, in this embodiment, the first measurement mark 105 is an integrated structure 170 , and the second measurement mark 101 is an integrated structure 170 .

[0061] Specifically, by setting the first measurement mark 105 as an integrated structure 170 and the second measurement mark 101 as an integrated structure 170, the boundary of the first measurement mark 105 and the boundary of the second measurement mark 101 are both uninterrupted boundaries. Therefore, in the process of measuring the first measurement mark 105 and the second measurement mark 101, the measurement machine can easily identify the uninterrupted boundaries, and the boundaries identified by the measurement machine are clearer, thereby improving the accuracy of obtaining the overlay error value. At the same time, when the boundaries of the first measurement mark 105 and the second measurement mark 101 are both uninterrupted boundaries, the scanning rate of the measurement machine can also be improved.

[0062] As an example, Fig. 9 As shown, the integrated structure 170 includes a strip-shaped structure.

[0063] In other embodiments, Fig.10 As shown, in the extension direction of the first measurement mark, the first measurement mark includes a plurality of first sub-measurement marks arranged at intervals; in the extension direction of the second measurement mark, the second measurement mark includes a plurality of second sub-measurement marks arranged at intervals.

[0064] Specifically, in the extension direction of the first measurement mark, a plurality of first sub-measurement marks arranged at intervals constitute the first measurement mark, so that the boundary of the overall contour of the first measurement mark composed of the plurality of first sub-measurement marks arranged at intervals is approximately an uninterrupted solid line. Accordingly, in the process of measuring the first measurement mark, the boundary of the overall contour of the first measurement mark composed of the plurality of first sub-measurement marks arranged at intervals is relatively clear, and the measuring machine can accurately scan and measure.

[0065] In the extension direction of the second measurement mark, a plurality of second sub-measurement marks arranged at intervals constitute the second measurement mark, so that the boundary of the overall contour of the second measurement mark composed of the plurality of second sub-measurement marks arranged at intervals is approximately an uninterrupted solid line. Accordingly, in the process of measuring the second measurement mark, the boundary of the overall contour of the second measurement mark composed of the plurality of second sub-measurement marks arranged at intervals is relatively clear, and the measuring machine can accurately scan and measure.

[0066] As an example, Fig.10 As shown, the first sub-measurement mark includes a hole-type structure, and the second sub-measurement mark includes a hole-type structure.

[0067] It should be noted that, in the extension direction of the first sub-measurement mark, the distance between adjacent first sub-measurement marks should not be too large or too small. If the distance between adjacent first sub-measurement marks is too large, it is easy to cause the boundary of the first measurement mark composed of multiple first sub-measurement marks to be unclear, so that the measurement machine cannot accurately identify the boundary of the first measurement mark during the measurement of the boundary of the first measurement mark, thereby affecting the accuracy of the overlay error value; if the distance between adjacent first sub-measurement marks is too small, the process difficulty of forming the first sub-measurement mark is increased in the formation process of the first sub-measurement mark, and the probability of pattern overlap between the first sub-measurement marks is increased, thereby affecting the accuracy of the overlay error value. For this reason, in the present embodiment, in the extension direction of the first sub-measurement mark, the distance between adjacent first sub-measurement marks is 1 nanometer to 200 nanometers.

[0068] It should also be noted that in the extension direction of the second sub-measurement mark, the distance between adjacent second sub-measurement marks should not be too large or too small. If the distance between adjacent second sub-measurement marks is too large, it is easy to cause the boundary of the second measurement mark composed of multiple second sub-measurement marks to be unclear, so that the measurement machine cannot accurately identify the boundary of the second measurement mark during the measurement of the boundary of the second measurement mark, thereby affecting the accuracy of the overlay error value; if the distance between adjacent second sub-measurement marks is too small, the process difficulty of forming the second sub-measurement mark is increased in the formation process of the second sub-measurement mark, and the probability of pattern overlap between the second sub-measurement marks is increased, thereby affecting the accuracy of the overlay error value. For this reason, in the present embodiment, in the extension direction of the second sub-measurement mark, the distance between adjacent second sub-measurement marks is 1 nanometer to 200 nanometers.

[0069] Accordingly, an embodiment of the present invention further provides a mask layout, which is suitable for forming the alignment mark provided by the embodiment of the present invention. Figure 3 as well as Figures 6 to 10 The mask of the present invention Figure 1 Schematic diagram corresponding to the embodiment.

[0070] The mask pattern includes: a first layer (not marked), including a detection opening pattern 108, wherein the opening pattern is used to form a detection opening in a dielectric layer; a second layer (not marked), located below the first layer, wherein the second layer includes a first measurement identification pattern 105, and after the second layer overlaps with the first layer, the detection opening pattern 108 has an overlapping portion with the first measurement identification pattern 105; a third layer (not marked), located between the second layer and the first layer, wherein the third layer includes a second measurement identification pattern 101, and after the third layer overlaps with the second layer, the second measurement identification pattern 101 is staggered with the first measurement identification pattern 105, and an extension direction of the second measurement identification pattern 101 is the same as an extension direction of the first measurement identification pattern 105.

[0071] It should be noted that the detection opening graphic 108 is used to form a detection opening in the dielectric layer. After the second plate layer and the first plate layer overlap, the detection opening graphic 108 has an overlapping portion with the first measurement mark graphic 105, which means that the detection opening exposes the top surface of the first measurement mark. In the process of scanning and measuring the first measurement mark, the boundary of the first measurement mark can be clearly visible, thereby improving the accuracy of measuring the first measurement mark. After measuring the second measurement mark, the accuracy of the overlay error value between the first measurement mark and the second measurement mark can also be improved.

[0072] The detection opening pattern 108 is used to form a detection opening in the dielectric layer. After the second layout layer and the first layout layer overlap, the detection opening pattern 108 has an overlapping portion with the first measurement mark pattern 105, which means that the detection opening exposes the top surface of the first measurement mark.

[0073] The first measurement mark pattern 105 is used to form a first measurement mark.

[0074] In this embodiment, the area where the first measurement identification graphic 105 is located is the first identification area (not marked), and the area where the second measurement identification graphic 101 is located is the second identification area (not marked). After the second layout layer overlaps with the first layout layer, along the extension direction of the first measurement identification graphic 105, the second identification area is located as a whole on the side of the first identification area.

[0075] Specifically, the second identification area is located as a whole on the side of the first identification area. In the process of setting the first measurement identification graphic 105 and the second measurement identification graphic 101, the first measurement identification graphic 105 and the second measurement identification graphic 101 can be made not to interfere with each other, which means that the size and pitch of the first measurement identification graphic 105 and the size and pitch of the second measurement identification graphic 101 can be freely and flexibly selected, and the probability of overlap between the first measurement identification graphic 105 and the second measurement identification graphic 101 is reduced, so that the overlay error value can be further accurately obtained.

[0076] In this embodiment, the area where the first measurement mark graphic 105 is located is the first mark area, and the area where the second measurement mark graphic 101 is located is the second mark area. The center point of the first mark area, the center point of the second mark area, and the center point of the detection opening graphic 108 are all located on the same vertical line, and the extension direction of the vertical line is the same as the extension direction of the first measurement mark, which is conducive to obtaining the overlay error value of the measurement mark with a height difference.

[0077] As an example, taking the direction perpendicular to the extension direction of the first measurement mark pattern 105 as the lateral direction, the lateral dimension of the detection opening pattern 108 and the pitch of the adjacent first measurement mark pattern 105 satisfy the relationship: D=2n*P; wherein D represents the lateral dimension of the detection opening pattern 108; P represents the pitch of the adjacent first measurement mark patterns 105; and n represents a positive integer.

[0078] By making the lateral dimension of the detection opening pattern 108 an integer multiple of the pitch of the adjacent first measurement mark pattern 105, it is possible to ensure that the boundary of the detection opening pattern 108 is exactly in the middle of the dielectric layer. Accordingly, in the process of measuring the first measurement mark pattern, the boundary of the first measurement mark can be fully identified, and the boundary of the first measurement mark covered by the dielectric layer will not be exposed, thereby maximizing the size of the detection opening pattern 108.

[0079] The second measurement mark pattern 101 is used to form a second measurement mark.

[0080] As an example, after the third layer and the second layer overlap, the second measurement identification graphic 101 is located in the medium layer and is staggered with the first measurement identification graphic 105. Specifically, the second measurement identification graphic 101 is staggered with the first measurement identification graphic 105, and the overlay error between the second measurement identification graphic 101 and the first measurement identification graphic 105 can be obtained.

[0081] refer to Figures 6 to 8The first measurement identification graphic 105 and the second measurement identification graphic 101 extending in the same direction constitute a measurement identification group graphic, and the measurement identification group graphic includes one or both of an X-direction identification group graphic and a Y-direction identification group graphic, and the X direction is perpendicular to the Y direction, wherein the first measurement identification graphic 105 and the second measurement identification graphic 101 in the X-direction identification group graphic both extend along the Y direction, and the first measurement identification graphic 105 and the second measurement identification graphic 101 in the Y-direction identification group both extend along the X direction.

[0082] It should be noted that the X-direction mark group pattern is used to measure the overlay error value in the X direction, and the Y-direction mark group pattern is used to measure the overlay error value in the Y direction.

[0083] It should also be noted that, when the measurement mark group pattern includes the X-direction mark group pattern and the Y-direction mark group pattern, the top surfaces of the first measurement mark pattern 105 of the X-direction mark group pattern and the Y-direction mark group pattern are respectively exposed by the corresponding detection opening patterns 108, so that the measurement machine can measure the boundary of the first measurement mark pattern 105 in the X-direction mark pattern and the boundary of the first measurement mark pattern 105 in the Y-direction mark group pattern through the corresponding detection opening patterns 108, respectively.

[0084] like Fig. 9 As shown, in this embodiment, the first measurement identification graphic 105 is an integrated structural graphic 170 , and the second measurement identification graphic 101 is an integrated structural graphic 170 .

[0085] Specifically, by setting the first measurement mark graphic 105 as an integrated structure and the second measurement mark graphic 101 as an integrated structure, the boundary of the first measurement mark graphic 105 and the boundary of the second measurement mark graphic 101 are both uninterrupted boundaries. Therefore, in the process of measuring the first measurement mark and the second measurement mark, the measurement machine can easily identify the uninterrupted boundaries, and the boundaries identified by the measurement machine are clearer, thereby improving the accuracy of obtaining the overlay error value. At the same time, when the boundaries of the first measurement mark and the second measurement mark are both uninterrupted boundaries, the scanning rate of the measurement machine can also be improved.

[0086] As an example, Fig. 9 As shown, the integrated structural pattern 170 includes a strip structure.

[0087] In other embodiments, Fig.10 As shown, in the extension direction of the first measurement identification pattern, the first measurement identification pattern includes a plurality of first sub-measurement identification patterns arranged at intervals; in the extension direction of the second measurement identification pattern, the second measurement identification pattern includes a plurality of second sub-measurement identification patterns arranged at intervals.

[0088] Specifically, in the extension direction of the first measurement identification pattern, a plurality of first sub-measurement identification patterns arranged at intervals constitute the first measurement identification pattern, so that the boundary of the overall contour of the first measurement identification pattern composed of the plurality of first sub-measurement identification patterns arranged at intervals is approximately an uninterrupted solid line. Accordingly, in the process of measuring the first measurement mark, the boundary of the overall contour of the first measurement mark composed of the plurality of first sub-measurement identification patterns arranged at intervals is relatively clear, and the measuring machine can accurately scan and perform measurements.

[0089] In the extension direction of the second measurement identification pattern, a plurality of second sub-measurement identification patterns arranged at intervals constitute the second measurement identification pattern, so that the boundary of the overall contour of the second measurement identification pattern composed of the plurality of second sub-measurement identification patterns arranged at intervals is approximately an uninterrupted solid line. Accordingly, in the process of measuring the second measurement mark, the boundary of the overall contour of the second measurement mark composed of the plurality of second sub-measurement identification patterns arranged at intervals is relatively clear, and the measuring machine can accurately scan and measure.

[0090] As an example, Fig.10 As shown, the first sub-measurement identification pattern includes a hole-type structure, and the second sub-measurement identification pattern includes a hole-type structure.

[0091] It should be noted that, in the extension direction of the first sub-measurement identification pattern, the distance between adjacent first sub-measurement identification patterns should not be too large or too small. If the distance between adjacent first sub-measurement identification patterns is too large, it is easy to cause the boundary of the first measurement identification pattern 105 composed of multiple first sub-measurement identification patterns to be unclear, so that the measurement machine cannot accurately identify the boundary of the first measurement identification during the measurement of the boundary of the first measurement identification, thereby affecting the accuracy of the overlay error value; if the distance between adjacent first sub-measurement identification patterns is too small, in the formation process of the first sub-measurement identification pattern, the difficulty of designing the first sub-measurement identification pattern is increased, and the probability of pattern overlap between the first sub-measurement identification patterns is increased, thereby affecting the accuracy of the overlay error value. For this reason, in the present embodiment, in the extension direction of the first sub-measurement identification pattern, the distance between adjacent first sub-measurement identification patterns is 1 nanometer to 200 nanometers.

[0092] It should also be noted that in the extension direction of the second sub-measurement identification pattern, the distance between adjacent second sub-measurement identification patterns should not be too large or too small. If the distance between adjacent second sub-measurement identification patterns is too large, it is easy to cause the boundary of the second measurement identification pattern composed of multiple second sub-measurement identification patterns to be unclear, so that the measurement machine cannot accurately identify the boundary of the second measurement identification during the measurement of the boundary of the second measurement identification, thereby affecting the accuracy of the overlay error value; if the distance between adjacent second sub-measurement identification patterns is too small, the difficulty of designing the second sub-measurement identification in the formation process of the second sub-measurement identification pattern is increased, and the probability of pattern overlap between the second sub-measurement identification patterns is increased, thereby affecting the accuracy of the overlay error value. For this reason, in the present embodiment, in the extension direction of the second sub-measurement identification pattern, the distance between adjacent second sub-measurement identification patterns is 1 nanometer to 200 nanometers.

[0093] Accordingly, an embodiment of the present invention further provides a method for forming an alignment mark. Figures 11 to 15 It is a structural schematic diagram corresponding to an embodiment of a method for forming an alignment mark of the present invention.

[0094] refer to Fig.12 , providing a substrate 120, wherein the substrate 120 includes a measurement area 100A.

[0095] The substrate 120 provides a process platform for forming the alignment mark.

[0096] It should be noted that with the continuous advancement of technology nodes, the overlay error is getting smaller and smaller. The overlay error measurement (OVL) after lithography development (ADI) uses a diffraction-based overlay mark (DBO mark). Affected by the etching process, the OVL value of the same measurement point from after development (ADI) to after etching (AEI) will have a fixed difference (AEI_ADI offset). In order to obtain a fixed difference to correct ADI, it is necessary to design a post-etching measurement mark to obtain OVL.

[0097] In this embodiment, the substrate 120 is a silicon substrate. In other embodiments, the substrate material may also be other materials such as germanium, silicon germanium, silicon carbide, gallium arsenide or indium gallium, and the substrate may also be other types of substrates such as a silicon on insulator substrate or a germanium on insulator substrate.

[0098] The measurement area 100A is used to set a measurement mark, and the overlay error value is calculated by measuring the measurement mark.

[0099] refer to Figures 11 to 14 ,in, Fig.11 It is a top view. Fig.13 yes Fig.11 Cross-sectional view along BB direction, Fig.14 yes Fig.11 In the cross-sectional view along the AA direction, a dielectric layer 102, and a first measurement mark 105 and a second measurement mark 101 located in the dielectric layer 102 are formed on the substrate 120, the second measurement mark 101 and the first measurement mark 105 are staggered, the extension direction of the second measurement mark 101 is the same as the extension direction of the first measurement mark 105, and the top surface of the second measurement mark 101 is higher than the top surface of the first measurement mark 105.

[0100] The dielectric layer 102 provides a process basis for setting the first measurement mark 105 and the second measurement mark 101 .

[0101] In this embodiment, the material of the dielectric layer 102 includes one or more of silicon oxide, silicon nitride and silicon oxynitride.

[0102] As an example, the first measurement mark 105 is located in the dielectric layer 102 and is covered by the dielectric layer 102 . Specifically, the first measurement mark 105 is a front layer mark.

[0103] As an example, the second measurement mark 101 is located in the dielectric layer 102 and is staggered with the first measurement mark 105. Specifically, the second measurement mark 101 and the first measurement mark 105 are staggered, and an overlay error between the second measurement mark 101 and the first measurement mark 105 can be obtained.

[0104] In this embodiment, the top surface of the second measurement mark 101 is higher than the top surface of the first measurement mark 105, which means that there is a height difference between the first measurement mark 105 and the second measurement mark 101. The ADI is corrected by obtaining the overlay error of the measurement mark with the height difference.

[0105] As an example, the second measurement identifier 101 is a current layer identifier.

[0106] It should be noted that the second measurement mark 101 is located in the dielectric layer 102 and the top surface of the second measurement mark 101 is exposed by the dielectric layer 102. Since the top surface of the second measurement mark 101 is exposed by the dielectric layer 102, the measuring machine can accurately identify the boundary of the second measurement mark 101 and perform measurement, thereby improving the accuracy of obtaining the overlay error value.

[0107] In this embodiment, the steps of forming a dielectric layer 102 on the substrate 120 and a first measurement mark 105 and a second measurement mark 101 located in the dielectric layer 102 include: forming the first measurement mark 105 on the substrate 120; forming a dielectric layer 102 covering the first measurement mark 105 on the substrate 120; and performing a graphing process on the dielectric layer 102 to form a second measurement mark 101 in the dielectric layer 102.

[0108] refer to Fig.15 A detection opening 108 is formed in the dielectric layer 102 of the measurement area 100A, and the detection opening 108 exposes the top surface of the first measurement mark 105 .

[0109] It should be noted that, by forming a detection opening 108 in the dielectric layer 102 of the measurement area 100A, the detection opening 108 exposes the top surface of the first measurement mark 105. During the process of scanning and measuring the first measurement mark 105, the boundary of the first measurement mark 105 can be clearly visible, thereby improving the accuracy of measuring the first measurement mark 105. After measuring the second measurement mark 101, the accuracy of the overlay error value between the first measurement mark 105 and the second measurement mark 101 can also be improved.

[0110] In this embodiment, the step of forming a detection opening 108 in the dielectric layer 102 of the measurement area 100A includes: forming a mask layer (not shown) having a mask opening on the top of the dielectric layer 102 of the measurement area 100A, wherein the mask opening is located above the first measurement mark 105 and exposes the dielectric layer 102 above the first measurement mark 105; using the mask layer as a mask, performing a patterning process on the dielectric layer 102 exposed by the mask opening, thereby forming the detection opening 108 in the dielectric layer 102 of the measurement area 100A.

[0111] In this embodiment, the process of patterning the dielectric layer 102 exposed by the mask opening using the mask layer as a mask includes a dry etching process.

[0112] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. An alignment mark, characterized in that: include: a substrate, including a measurement area; A dielectric layer, located on the top of the substrate, wherein the dielectric layer has a detection opening located in the measurement area; A first measurement mark is located in the dielectric layer, and a top surface of the first measurement mark located in the measurement area is exposed by the detection opening; The second measurement mark is located in the dielectric layer and is staggered with the first measurement mark. The extension direction of the second measurement mark is the same as the extension direction of the first measurement mark, and the top surface of the second measurement mark is higher than the top surface of the first measurement mark.

2. The alignment mark according to claim 1, wherein: The area where the first measurement mark is located is the first identification area, and the area where the second measurement mark is located is the second identification area. Along the extension direction of the first measurement mark, the second identification area is entirely located on the side of the first identification area.

3. The alignment mark according to claim 1, wherein: The area where the first measurement mark is located is the first identification area, and the area where the second measurement mark is located is the second identification area. The center point of the first identification area, the center point of the second identification area, and the center point of the detection opening are all located on the same vertical line, and the extension direction of the vertical line is the same as the extension direction of the first measurement mark.

4. The alignment mark according to claim 1 or 3, characterized in that: Taking the direction perpendicular to the extension direction of the first measurement mark as the lateral direction, the lateral dimension of the detection opening and the pitch of adjacent first measurement marks satisfy the relationship: D=2n*P; wherein D represents the lateral dimension of the detection opening; P represents the pitch of adjacent first measurement marks; and n represents a positive integer.

5. The alignment mark according to claim 1, wherein: The first measurement mark and the second measurement mark extending in the same direction constitute a measurement mark group, wherein the measurement mark group includes one or both of an X-direction mark group and a Y-direction mark group, and the X-direction is perpendicular to the Y-direction; The first measurement mark and the second measurement mark in the X-direction mark group both extend along the Y-direction, and the first measurement mark and the second measurement mark in the Y-direction mark group both extend along the X-direction.

6. The alignment mark according to claim 1, wherein: The first measurement mark is an integrated structure, and the second measurement mark is an integrated structure; or, In the extending direction of the first measurement mark, the first measurement mark includes a plurality of first sub-measurement marks arranged at intervals; in the extending direction of the second measurement mark, the second measurement mark includes a plurality of second sub-measurement marks arranged at intervals.

7. The alignment mark according to claim 6, wherein: The integrated structure includes a strip-shaped structure; The first sub-measurement mark includes a hole-type structure, and the second sub-measurement mark includes a hole-type structure.

8. The alignment mark according to claim 6, wherein: In the extension direction of the first sub-measurement mark and the second sub-measurement mark, the distance between adjacent first sub-measurement marks is 1 nanometer to 200 nanometers, and the distance between adjacent second sub-measurement marks is 1 nanometer to 200 nanometers.

9. The alignment mark according to claim 1, wherein: The material of the dielectric layer includes one or more of silicon oxide, silicon nitride and silicon oxynitride.

10. A mask layout, characterized in that: Suitable for forming the alignment mark according to any one of claims 1 to 9, the mask pattern comprising: A first layer, comprising a detection opening pattern, wherein the detection opening pattern is used to form a detection opening in the dielectric layer; A second layer is located below the first layer, the second layer includes a first measurement mark pattern, and after the second layer overlaps with the first layer, the detection opening pattern has an overlapping portion with the first measurement mark pattern; The third layer is located between the second layer and the first layer, and the third layer includes a second measurement identification graphic. After the third layer overlaps with the second layer, the second measurement identification graphic and the first measurement identification graphic are staggered, and an extension direction of the second measurement identification graphic is the same as an extension direction of the first measurement identification graphic.

11. The mask layout according to claim 10, characterized in that: The area where the first measurement identification graphic is located is the first identification area, and the area where the second measurement identification graphic is located is the second identification area. After the second layer and the first layer overlap, along the extension direction of the first measurement identification graphic, the second identification area is located as a whole on the side of the first identification area.

12. The mask layout according to claim 10, characterized in that: The area where the first measurement identification graphic is located is the first identification area, and the area where the second measurement identification graphic is located is the second identification area. After the first layer, the second layer and the third layer overlap, the center point of the first identification area, the center point of the second identification area, and the center point of the detection opening graphic are all located on the same vertical line, and the extension direction of the vertical line is the same as the extension direction of the first measurement identification graphic.

13. The mask layout according to claim 10 or 12, characterized in that: Taking the direction perpendicular to the extension direction of the first measurement mark pattern as the lateral direction, the lateral dimension of the detection opening pattern and the pitch of the adjacent first measurement mark pattern need to satisfy the relationship: D=2n*P; wherein D represents the lateral dimension of the detection opening pattern; P represents the pitch of the adjacent first measurement mark pattern; n represents a positive integer.

14. The mask layout according to claim 10, characterized in that: After the third layer overlaps with the second layer, the first measurement mark pattern and the second measurement mark pattern extending in the same direction constitute a measurement mark group pattern, wherein the measurement mark group pattern includes one or both of an X-direction mark group pattern and a Y-direction mark group pattern, and the X direction is perpendicular to the Y direction; The first measurement identification graphic and the second measurement identification graphic in the X-direction identification group graphic both extend along the Y-direction, and the first measurement identification graphic and the second measurement identification graphic in the Y-direction identification group graphic both extend along the X-direction.

15. The mask layout according to claim 10, characterized in that: The first measurement identification graphic is an integrated structural graphic, and the second measurement identification graphic is an integrated structural graphic; Alternatively, in the extension direction of the first measurement identification pattern, the first measurement identification pattern includes a plurality of first sub-measurement identification patterns arranged at intervals; in the extension direction of the second measurement identification pattern, the second measurement identification pattern includes a plurality of second sub-measurement identification patterns arranged at intervals.

16. The mask layout according to claim 15, characterized in that: The integrated structural pattern includes a strip-shaped structural pattern; The first sub-measurement identification pattern includes a hole-type structure pattern, and the second sub-measurement identification pattern includes a hole-type structure pattern.

17. The mask layout according to claim 15, characterized in that: In the extending direction of the first sub-measurement identification pattern and the second sub-measurement identification pattern, the distance between adjacent first sub-measurement identification patterns is 1 nanometer to 200 nanometers, and the distance between adjacent second sub-measurement identification patterns is 1 nanometer to 200 nanometers.

18. A method for forming an alignment mark, characterized in that: include: providing a substrate, the substrate comprising a measurement area; A dielectric layer, and a first measurement mark and a second measurement mark located in the dielectric layer are formed on the substrate, wherein the second measurement mark and the first measurement mark are staggered, an extension direction of the second measurement mark is the same as an extension direction of the first measurement mark, and a top surface of the second measurement mark is higher than a top surface of the first measurement mark; A detection opening is formed in the dielectric layer of the measurement area, and the detection opening exposes the top surface of the first measurement mark.

19. The method for forming an alignment mark according to claim 18, wherein: The steps of forming a dielectric layer on the substrate, and a first measurement mark and a second measurement mark in the dielectric layer include: forming a first measurement mark on the substrate; forming a dielectric layer covering the first measurement mark on the substrate; and performing graphic processing on the dielectric layer to form a second measurement mark in the dielectric layer.

20. The method for forming an alignment mark according to claim 18, wherein: The step of forming a detection opening in the dielectric layer of the measurement area includes: forming a mask layer having a mask opening on the top of the dielectric layer of the measurement area, wherein the mask opening is located above the first measurement mark and exposes the dielectric layer above the first measurement mark; using the mask layer as a mask, performing a graphic processing on the dielectric layer exposed by the mask opening, and forming a detection opening in the dielectric layer of the measurement area.

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