An alignment mark and a counter-alignment mark for bonding, a semiconductor structure

Abstract

The present disclosure provides a kind of for bonding alignment mark and matching alignment mark, semiconductor structure. Wherein, the alignment mark includes multiple sub-alignment marks;Multiple sub-alignment marks are arranged at intervals, wherein the pitch of two adjacent sub-alignment marks is less than the minimum resolution of identification lens;The alignment mark is located on the surface of substrate;Sub-alignment mark is composed of metal material, and is surrounded by dielectric material.

Description

Technical Field

[0001] This disclosure relates to semiconductor manufacturing technology, and more particularly to an alignment mark and mating alignment mark for bonding, and a semiconductor structure. Background Technology

[0002] Hybrid bonding is an important step in semiconductor manufacturing processes, combining dielectric-dielectric bonding and metal-metal bonding to achieve wafer-to-wafer, chip-to-wafer, or chip-to-chip interconnections without the use of solder or other adhesives.

[0003] Hybrid bonding involves chemical mechanical polishing (CMP) and annealing. During CMP, the polishing pad simultaneously abrades both the dielectric and metallic materials to planarize the bonding interface between the two substrates to be bonded. High-temperature annealing then allows covalent bonds to form between the dielectric materials, while the metallic material diffuses across the interface to achieve metallurgical bonding, thus forming a reliable hybrid bonding interface. In related technologies, during CMP, the polishing pad abrades the alignment marks on the substrate surface, causing indentations in these marks. Similarly, during annealing, thermal expansion of the alignment marks can also lead to indentations, resulting in bubble formation after bonding and ultimately reducing the yield of semiconductor products. Summary of the Invention

[0004] This disclosure provides an alignment mark and a mating alignment mark for bonding, and a semiconductor structure.

[0005] The technical solution disclosed herein is implemented as follows: In a first aspect, this disclosure provides an alignment mark for bonding, the alignment mark being enclosed; the alignment mark includes: a plurality of sub-alignment marks; the plurality of sub-alignment marks are spaced apart, wherein the distance between two adjacent sub-alignment marks is less than the minimum resolution of the recognition lens; the alignment mark is located on the surface of a substrate; the sub-alignment marks are made of a metallic material and are surrounded by a dielectric material.

[0006] In some embodiments of this disclosure, a sub-alignment mark is circular; multiple sub-alignment marks are arranged in a concentric nested arrangement.

[0007] In some embodiments of this disclosure, a sub-alignment mark is fan-shaped; multiple sub-alignment marks are arranged sequentially along the circumferential direction to form a ring.

[0008] In some embodiments of this disclosure, a sub-alignment mark is fan-shaped; multiple sub-alignment marks are arranged sequentially along the circumferential direction to form multiple rings; the multiple rings are arranged in a concentric nested arrangement.

[0009] In some embodiments of this disclosure, the ring width of the sub-alignment marks located on the outer ring is greater than the ring width of the sub-alignment marks located on the inner ring.

[0010] In some embodiments of this disclosure, the spacing between two adjacent sub-alignment marks increases or decreases sequentially from the outside to the inside of the alignment marks.

[0011] In some embodiments of this disclosure, at least some of the sub-alignment marks have blind holes formed; the aperture of the blind hole is smaller than the minimum resolution of the recognition lens.

[0012] In a second aspect, this disclosure provides a mating alignment mark for bonding, the mating alignment mark comprising two alignment marks as described in the first aspect.

[0013] Thirdly, this disclosure provides a semiconductor structure, the semiconductor structure comprising: a first substrate and a second substrate bonded together; on the surfaces of the first substrate and the second substrate bonded together, at least one alignment mark as described in the first aspect is respectively provided; wherein, the inner ring radius of the alignment mark on the surface of the first substrate is greater than the outer ring radius of the alignment mark on the surface of the second substrate, or, the outer ring radius of the alignment mark on the surface of the first substrate is smaller than the inner ring radius of the alignment mark on the surface of the second substrate.

[0014] In some embodiments of this disclosure, the surfaces on which the first substrate and the second substrate are bonded to each other are planarized by a chemical mechanical polishing process and then annealed before bonding.

[0015] It is understood that the alignment mark for bonding provided in this embodiment consists of multiple sub-alignment marks made of metal materials on the substrate surface. That is, dividing a single, large-area metal alignment mark into multiple, small-area metal alignment marks can suppress indentations caused by chemical mechanical polishing and alleviate further deformation caused by the mismatch of thermal expansion coefficients between the metal and dielectric materials. This significantly reduces bubbles generated during hybrid bonding, thereby improving product yield. Furthermore, since the spacing between two adjacent sub-alignment marks is less than the minimum resolution of the recognition lens, the recognition lens can still identify multiple sub-alignment marks as a single alignment mark, thus preserving the pattern of the alignment marks before division and ensuring full compatibility with alignment algorithms in related technologies. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the alignment marks provided in the embodiments of this disclosure. Figure 1 ; Figure 2 This is a schematic diagram of the alignment marks provided in the embodiments of this disclosure. Figure 2 ; Figure 3This is a schematic diagram of the alignment marks provided in the embodiments of this disclosure. Figure 3 ; Figure 4 This is a schematic diagram of the alignment marks provided in the embodiments of this disclosure. Figure 4 ; Figure 5 This is a schematic diagram of the alignment marks provided in the embodiments of this disclosure. Figure 5 ; Figure 6 This is a schematic diagram of the alignment marks provided in the embodiments of this disclosure. Figure 6 ; Figure 7 This is a schematic diagram of the alignment marks provided in the embodiments of this disclosure. Figure 7 ; Figure 8 This is a schematic diagram of the alignment marks provided in the embodiments of this disclosure. Figure 8 ; Figure 9 This is a schematic diagram of the pairing alignment marks provided in an embodiment of this disclosure. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this disclosure clearer, the technical solutions of this disclosure are further described in detail below with reference to the accompanying drawings and embodiments. The described embodiments should not be regarded as limitations on this disclosure. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0018] In the following description, references are made to “some embodiments,” which describe a subset of all possible embodiments. However, it is understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0019] If the application documents contain similar descriptions such as "first / second", the following explanation shall be added: In the following description, the terms "first / second / third" are used only to distinguish similar objects and do not represent a specific order of objects. It is understood that "first / second / third" may be interchanged in a specific order or sequence where permitted, so that the embodiments of this disclosure described herein can be implemented in an order other than that illustrated or described herein.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The terminology used herein is for the purpose of describing embodiments of this disclosure only and is not intended to be limiting of this disclosure.

[0021] This disclosure provides an alignment mark for bonding, which is made of a metallic material, located on the surface of a substrate, and surrounded by a dielectric material, for use in hybrid bonding processes to achieve wafer-to-wafer interconnection, chip-to-wafer interconnection, and chip-to-chip interconnection. Figure 1 This is a schematic diagram of an optional structure of the alignment mark provided in an embodiment of this disclosure. The following will be combined with... Figure 1 Please provide an explanation.

[0022] like Figure 1 As shown, the alignment mark 100 is enclosed; the alignment mark 100 includes multiple sub-alignment marks, such as sub-alignment mark 101 and sub-alignment mark 102, which are spaced apart. The distance between two adjacent sub-alignment marks is less than the minimum resolution of the recognition lens. The sub-alignment marks are made of metallic material and surrounded by a dielectric material.

[0023] In this disclosure embodiment, reference is made to Figure 1 Sub-alignment marks 101 and 102 are part of alignment mark 100, wherein each sub-alignment mark is relatively independent but constitutes a whole. The multiple sub-alignment marks in this disclosure are not connected (i.e., spaced apart), and the gap between two adjacent sub-alignment marks is filled with a dielectric material for isolation (i.e., surrounded by a dielectric material).

[0024] In this embodiment of the present disclosure, during the bonding process, the recognition lens in the bonding device can acquire the alignment mark 100, wherein the recognition lens refers to the optical imaging lens mounted on the bonding device. Since the distance between the sub-alignment marks 101 and 102 is less than the minimum resolution of the recognition lens, the recognition lens cannot distinguish the boundary between the sub-alignment marks 101 and 102. In this way, the sub-alignment marks 101 and 102 can be recognized by the recognition lens as a whole to realize the function of the alignment mark, thereby being compatible with existing alignment algorithms and alignment devices. At the same time, the recognition lens recognizes multiple sub-alignment marks as a whole rather than multiple independent alignment marks, thus avoiding phenomena such as positioning coordinate disorder, alignment failure, and bonding offset during alignment.

[0025] In some embodiments of this disclosure, multiple sub-alignment marks are arranged around the same center so that the alignment marks are enclosed in shape. For example, see reference... Figure 1 The enclosing sub-alignment marks 101 and 102 surround the same center, and the interval between the sub-alignment marks 101 and 102 is less than the minimum resolution of the recognition lens. This allows the recognition lens to perceive the shape of the alignment mark 100 as enclosing; or, refer to... Figure 2Multiple sub-alignment marks 201 are arranged sequentially around the same center, so that the shape of alignment mark 100 can be recognized by the recognition lens as an enclosed shape.

[0026] It should be noted that this disclosure does not limit the number of sub-alignment marks, nor does it limit the shape of the sub-alignment marks, as long as the distance between two adjacent sub-alignment marks is less than the minimum resolution of the recognition lens. For example, the shape of the sub-alignment marks can be a circular ring, a fan ring, a sawtooth shape, etc.

[0027] Understandably, since the alignment mark is made of a metallic material with a different hardness than the surrounding medium, during chemical mechanical polishing (CMP), the polishing pad polishes both the alignment mark and the surrounding medium simultaneously. The different stresses experienced by the alignment mark and the medium result in different grinding rates, thus posing a risk of indentation. In this embodiment, the area enclosed by the alignment mark and its surrounding area are filled with a medium. Because the medium is harder than the metallic material, it provides support to the polishing pad during CMP, resulting in a more uniform stress distribution and reducing the risk of indentation. Furthermore, by using multiple smaller sub-alignment marks to divide the alignment mark area, the distribution of both the metallic and medium materials becomes more uniform, further enhancing the uniform stress distribution during CMP and further reducing the risk of indentation.

[0028] Furthermore, since the coefficient of thermal expansion of the alignment mark's metallic material is higher than that of the surrounding dielectric material, during annealing, the expanding metallic material is constrained by the surrounding dielectric material, preventing it from extending horizontally and limiting its extension to a direction perpendicular to the substrate surface. This also poses a risk of forming a depression. However, in this embodiment, because the sub-alignment mark has a smaller area, its expansion during annealing is less. This reduces the amount of metal extending perpendicular to the substrate surface, thereby suppressing the risk of depressions during annealing.

[0029] In summary, in this embodiment, the spaced sub-alignment marks have a smaller area ratio, which can suppress the risk of depressions in the bonding process and avoid the formation of bubble defects after bonding, thereby improving product yield. Furthermore, in this embodiment, the spacing between two adjacent sub-alignment marks is less than the minimum resolution of the recognition lens. This allows multiple spaced sub-alignment marks to be recognized as a single unit, enabling the shape of the alignment marks to be constructed according to the needs of the bonding equipment and ensuring compatibility with existing bonding devices.

[0030] In some embodiments of this disclosure, reference is made to Figure 1 A sub-alignment mark (e.g., sub-alignment mark 101) is circular, and multiple sub-alignment marks (e.g., sub-alignment mark 101 and sub-alignment mark 102) are arranged in a concentric nested arrangement.

[0031] In this disclosure embodiment, reference is made to Figure 1 The sub-alignment marks 101 and 102 are circular in shape, nested together with their geometric centers coinciding at the same point, forming concentric rings. Sub-alignment mark 101 is located on the outer ring, and sub-alignment mark 102 is located on the inner ring. The difference between the inner radius of sub-alignment mark 101 and the outer radius of sub-alignment mark 102 is less than the minimum resolution of the recognition lens (i.e., the distance between two adjacent rings is less than the minimum resolution of the recognition lens).

[0032] It should be noted that this disclosure does not limit the number of annular sub-alignment marks, which can be adjusted as needed.

[0033] It is understood that in this embodiment of the present disclosure, multiple annular sub-alignment marks are arranged concentrically, and the distance between two adjacent annular marks is less than the minimum resolution of the recognition lens, so that the overall shape of the alignment mark 100 recognized by the recognition lens is an annular shape. Since the annular shape is centrally symmetrical, the recognition lens is not affected by the rotation angle of the alignment mark, thereby enabling the accurate detection of any offset of the alignment mark in any direction, thus improving alignment accuracy.

[0034] In some embodiments of this disclosure, reference is made to Figure 2 One sub-alignment mark 201 is marked in a fan-shaped ring. Multiple sub-alignment marks 201 are arranged sequentially along the circumference to form a ring.

[0035] In this disclosure embodiment, reference is made to Figure 2 Each sub-alignment mark 201 has a fan-shaped geometry, and these fan-shaped sub-alignment marks 201 are arranged sequentially around the same center to form a ring. The spacing between two adjacent fan rings is less than the minimum resolution of the recognition lens.

[0036] It should be noted that this disclosure does not limit the size of the central angle of the sub-alignment mark of the fan ring shape, and it can be adjusted as needed.

[0037] It is understood that in this embodiment of the present disclosure, multiple fan-shaped sub-alignment marks 201 are arranged sequentially along the circumferential direction, and the spacing between two adjacent fan rings is less than the minimum resolution of the recognition lens. This allows the recognition lens to recognize a circular pattern, making the overall shape of the alignment mark 100 recognized by the recognition lens a circular ring. Since the circular ring has a centrally symmetrical structure, the recognition lens is not affected by the rotation angle of the alignment mark, thereby enabling accurate detection of any offset of the alignment mark in any direction, thus improving alignment accuracy.

[0038] In some embodiments of this disclosure, reference is made to Figure 3 A sub-alignment mark (e.g., sub-alignment mark 201) is arranged in a fan-shaped ring. Multiple sub-alignment marks (e.g., sub-alignment mark 201 and sub-alignment mark 202) are arranged sequentially along the circumferential direction to form multiple rings; the multiple rings are arranged in a concentric nested arrangement.

[0039] In this disclosure embodiment, reference is made to Figure 3 Both sub-alignment marks 201 and 202 are geometrically fan-shaped rings. Multiple fan-shaped sub-alignment marks 201 are arranged sequentially along the circumference to form one ring; multiple fan-shaped sub-alignment marks 202 are arranged sequentially along the circumference to form another ring. These two rings are nested and their geometric centers coincide at the same point, forming concentric rings. In other words, multiple fan-shaped sub-alignment marks form multiple rings, which together constitute a concentric nested structure.

[0040] It should be noted that this disclosure does not limit the number of rings formed by the sub-alignment marks of the sector ring, and can be adjusted according to requirements.

[0041] It is understood that in this embodiment, the multiple concentric rings are composed of multiple fan-ring shaped sub-alignment marks. Since the spacing between adjacent fan rings within the same ring and the spacing between adjacent rings are both less than the minimum resolution of the recognition lens, the recognition lens can identify these discrete fan rings as a continuous and complete ring, thus retaining the advantages of the ring-shaped alignment marks. Simultaneously, since each ring is composed of spaced-apart fan rings, the metal area of ​​each fan ring is much smaller than that of a complete continuous ring. This further reduces the stress experienced by the sub-alignment marks during chemical mechanical polishing and further reduces the expansion of the sub-alignment marks during annealing, thereby further suppressing the formation of depressions.

[0042] In some embodiments of this disclosure, reference is made to Figure 4 and Figure 5 The ring width of the sub-alignment mark located on the outer ring is greater than the ring width of the sub-alignment mark located on the inner ring.

[0043] In this disclosure embodiment, reference is made to Figure 4 In the concentric rings formed by multiple annular sub-alignment marks, the ring width of the outer sub-alignment mark 101 is greater than the ring width of the inner sub-alignment mark 103. (Reference) Figure 5 In the concentric rings formed by multiple fan-shaped sub-alignment marks, the ring width of the outer sub-alignment mark 201 is greater than the ring width of the inner sub-alignment mark 203. The ring width refers to the difference between the outer radius and the inner radius of the ring formed by the sub-alignment marks. For example, the ring width refers to the difference between the outer radius and the inner radius of the sub-alignment mark 101.

[0044] Understandably, during chemical mechanical polishing, the linear velocity of the polishing pad gradually increases from the inner to the outer ring of the concentric rings. This results in a greater amount of metal removal on the outer ring compared to the inner ring, leading to deeper depressions on the outer ring and thus an uneven surface. In this embodiment, the differentiated design, where the ring width of the sub-alignment marks on the outer ring is greater than that on the inner ring, increases the proportion of metal material per unit area of ​​the sub-alignment marks on the outer ring. This compensates for the higher metal removal rate on the outer ring, thereby creating a flatter surface.

[0045] In some embodiments of this disclosure, reference is made to Figure 6 and Figure 7 The spacing between two adjacent sub-alignment marks increases or decreases sequentially from the outside to the inside of the alignment mark.

[0046] In this disclosure embodiment, reference is made to Figure 6 When the degree of indentation caused by chemical mechanical polishing is greater than that caused by annealing (i.e., chemical mechanical polishing is the main cause of bubbles), the interval between sub-alignment marks 101 and 102 is smaller than the interval between sub-alignment marks 102 and 104. In other words, from the outer ring to the inner ring of alignment marks 100, the spacing between two adjacent sub-alignment marks gradually increases. (Reference) Figure 7 When the degree of indentation caused by chemical mechanical polishing is less than that caused by annealing (i.e., annealing is the main cause of bubbles), the spacing between sub-alignment marks 101 and 102 is greater than the spacing between sub-alignment marks 102 and 104. In other words, the spacing between two adjacent sub-alignment marks gradually decreases from the outer ring to the inner ring of alignment marks 100. Here, the spacing refers to the difference between the inner radius of the sub-alignment mark located on the outer ring and the outer radius of the sub-alignment mark located on the inner ring. For example, the spacing is equal to the difference between the inner radius of sub-alignment mark 101 and the outer radius of sub-alignment mark 102.

[0047] Understandably, during chemical mechanical polishing (CMP), the linear velocity of the polishing pad gradually increases from the inner to the outer rings, resulting in greater metal removal on the outer rings compared to the inner rings. This leads to deeper depressions on the outer rings, causing air bubbles to form. When the primary goal is to mitigate the depressions caused by CMP, a smaller spacing between the outer rings increases the proportion of metal material per unit area of ​​the sub-alignment marks. This compensates for the higher metal removal rate on the outer rings, thus suppressing their depressions.

[0048] In addition, when annealing-induced depressions are the main cause of bubble formation, by setting a larger spacing between the outer rings, more dielectric material can absorb the thermal stress generated by the thermal expansion of the metal material, thereby reducing the depressions caused by annealing and suppressing bubble formation.

[0049] In some embodiments of this disclosure, reference is made to Figure 8 At least some of the alignment marks contain blind holes. The diameter of the blind hole is smaller than the minimum resolution of the recognition lens.

[0050] In this disclosure embodiment, reference is made to Figure 8 At least one blind hole (e.g., blind hole 301 and blind hole 302) is provided inside at least one sub-alignment mark (e.g., sub-alignment mark 101 and / or sub-alignment mark 102). Since the aperture of each blind hole is smaller than the minimum resolution of the recognition lens, the recognition lens can prevent the sub-alignment mark with the blind hole from being identified as multiple patterns. Here, a blind hole refers to a recessed hole structure opened inside the sub-alignment mark, which may penetrate the entire sub-alignment mark (but not through the substrate), or it may not penetrate the entire sub-alignment mark (i.e., there is still metal material at the bottom).

[0051] It should be noted that this disclosure does not limit the shape or number of blind holes, and adjustments can be made as needed. For example, the shape of a blind hole can be annular, square, star-shaped, etc.

[0052] Understandably, by creating blind holes inside the sub-alignment marks, the proportion of metal material per unit area of ​​the sub-alignment marks can be further reduced, thereby further suppressing the depressions caused by chemical mechanical polishing and annealing. Furthermore, by setting the aperture of each blind hole to be smaller than the minimum resolution of the recognition lens, the recognition lens can identify the sub-alignment marks with blind holes as a complete, continuous pattern. Combined with the fact that the spacing between two adjacent sub-alignment marks is smaller than the minimum resolution of the recognition lens, multiple sub-alignment marks can still be identified as a whole, retaining the function of alignment marks.

[0053] Based on the above embodiments, this disclosure also provides a mating alignment mark 200 for bonding, see reference. Figure 9 The pairing alignment mark 200 includes alignment mark 110 and alignment mark 120. Alignment mark 110 and alignment mark 120 are designed with reference to alignment mark 100 provided in the above embodiment. That is, alignment mark 110 and alignment mark 120 each include multiple sub-alignment marks, and the interval between each sub-alignment mark is set, and the interval between two adjacent sub-alignment marks is less than the minimum resolution of the recognition lens.

[0054] In this disclosure embodiment, reference is made to Figure 9 Alignment marks 110 and 120 are located on two substrates to be bonded, respectively, and are structurally matched. Alignment marks 110 and 120 have identical shapes and include the same number of sub-alignment marks. For example, alignment mark 110 includes sub-alignment marks 111, 112, and 113, and alignment mark 120 includes sub-alignment marks 121, 122, and 123. During bonding, alignment marks 110 and 120 are positioned relative to each other; for example, alignment mark 110 is located on the lower surface of the upper substrate, and alignment mark 120 is located on the upper surface of the lower substrate. The alignment process using the mating alignment marks 200 provided in this embodiment includes: extracting the coordinates of the geometric centers of alignment marks 110 and 120 respectively using a bonding device, calculating the relative deviation of the coordinates of the geometric centers, and then performing alignment based on the relative deviation.

[0055] Understandably, since each alignment mark in the pairing alignment marks includes multiple sub-alignment marks, and these sub-alignment marks occupy a smaller proportion of the metal material per unit area, this can suppress the depressions caused by chemical mechanical polishing and annealing, thereby significantly reducing the formation of bubbles after bonding.

[0056] Based on the above embodiments, this disclosure also provides a semiconductor structure, the semiconductor structure including: a first substrate and a second substrate bonded to each other; on the surfaces of the first substrate and the second substrate bonded to each other, at least one alignment mark for bonding provided in the above embodiments is respectively provided; wherein, the inner ring radius of the alignment mark on the surface of the first substrate is greater than the outer ring radius of the alignment mark on the surface of the second substrate, or the outer ring radius of the alignment mark on the surface of the first substrate is smaller than the inner ring radius of the alignment mark on the surface of the second substrate.

[0057] In this disclosure embodiment, reference is made to Figure 9At least one pairing alignment mark 100 is disposed on the bonding interface of the first substrate and the second substrate. Specifically, at least one alignment mark 110 or alignment mark 120 is disposed on the bonding surface of the first substrate, and at least one alignment mark 110 and another alignment mark 120 are disposed on the bonding surface of the second substrate. Each alignment mark includes multiple sub-alignment marks, and the multiple sub-alignment marks within each alignment mark are spaced apart. The distance between two adjacent sub-alignment marks belonging to the same alignment mark is less than the minimum resolution of the recognition lens, so that the alignment marks on each substrate are recognized as a whole. The sizes of the alignment marks on the first substrate and the second substrate are different; that is, the inner radius of the alignment mark on the surface of the first substrate is larger than the outer radius of the alignment mark on the surface of the second substrate, or the outer radius of the alignment mark on the surface of the first substrate is smaller than the inner radius of the alignment mark on the surface of the second substrate.

[0058] It is understood that the semiconductor structure provided in this disclosure can suppress indentations caused by bonding by using sub-alignment marks with a smaller proportion of metal material per unit area for bonding. By setting alignment marks of different sizes, when misalignment occurs, the recognition lens can intuitively capture the direction of the smaller alignment mark deviating from the larger alignment mark, thereby achieving rapid alignment.

[0059] In some embodiments of this disclosure, the surfaces on which the first substrate and the second substrate are bonded to each other are planarized by a chemical mechanical polishing process and then annealed before bonding.

[0060] In this embodiment of the disclosure, chemical mechanical polishing refers to planarizing the surfaces bonded to the first and second substrates through chemical etching and mechanical grinding. Annealing refers to heating the chemically mechanically polished substrate to a certain temperature (e.g., 300°C), holding it for a period of time, and then slowly cooling it to remove adsorbed moisture and organic matter from the surface, thereby improving the conductivity and bonding strength of the metallic materials.

[0061] It is understood that, prior to bonding, the alignment marks of the first and second substrates provided in this disclosure can be chemically mechanically polished to eliminate localized protrusions caused by electroplating and film deposition, thereby homogenizing the height of the bonding surface. Annealing the chemically mechanically polished surface can improve the conductivity of the metal material and the bonding strength after bonding. Furthermore, bonding using alignment marks composed of multiple sub-alignment marks with smaller metal material proportions per unit area and spaced apart, as provided in this disclosure, can simultaneously suppress depressions caused by chemically mechanical polishing and annealing, thereby significantly reducing the formation of bubbles after bonding and improving product yield.

[0062] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0063] The sequence numbers of the embodiments disclosed above are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments. The methods disclosed in the several method embodiments provided in this disclosure can be arbitrarily combined to obtain new method embodiments without conflict. The features disclosed in the several product embodiments provided in this disclosure can be arbitrarily combined to obtain new product embodiments without conflict. The features disclosed in the several method or device embodiments provided in this disclosure can be arbitrarily combined to obtain new method embodiments or device embodiments without conflict.

[0064] The above are merely specific embodiments of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. An alignment mark for bonding, characterized in that, The alignment mark is enclosed; the alignment mark includes: multiple sub-alignment marks; The plurality of sub-alignment marks are spaced apart, wherein the distance between two adjacent sub-alignment marks is less than the minimum resolution of the recognition lens; The alignment mark is located on the surface of the substrate; the sub-alignment mark is made of a metallic material and is surrounded by a dielectric material.

2. The alignment mark according to claim 1, characterized in that, One of the sub-alignment marks is in the shape of a ring; The multiple sub-alignment marks are arranged in a concentric nested pattern.

3. The alignment mark according to claim 1, characterized in that, One of the sub-alignment marks is in the shape of a fan ring; Multiple sub-alignment marks are arranged sequentially along the circumferential direction to form a ring.

4. The alignment mark according to claim 1, characterized in that, One of the sub-alignment marks is in the shape of a fan ring; Multiple sub-alignment marks are arranged sequentially along the circumferential direction to form multiple rings; the multiple rings are arranged in a concentric nested arrangement.

5. The alignment mark according to claim 2 or 4, characterized in that, The ring width of the sub-alignment mark located on the outer ring is greater than the ring width of the sub-alignment mark located on the inner ring.

6. The alignment mark according to claim 2, characterized in that, The spacing between two adjacent sub-alignment marks increases or decreases sequentially from the outside to the inside of the alignment marks.

7. The alignment mark according to claim 1, characterized in that, At least a portion of the sub-alignment marks have blind holes formed in them; the diameter of the blind holes is smaller than the minimum resolution of the recognition lens.

8. A pairing alignment mark for bonding, characterized in that, The pairing alignment marks include two alignment marks as described in any one of claims 1 to 7.

9. A semiconductor structure, characterized in that, The semiconductor structure includes: a first substrate and a second substrate bonded together; On the surfaces where the first substrate and the second substrate are bonded to each other, at least one alignment mark as described in any one of claims 1-7 is respectively provided; wherein, the inner ring radius of the alignment mark on the surface of the first substrate is greater than the outer ring radius of the alignment mark on the surface of the second substrate, or, the outer ring radius of the alignment mark on the surface of the first substrate is smaller than the inner ring radius of the alignment mark on the surface of the second substrate.

10. The semiconductor structure according to claim 9, characterized in that, The surfaces on which the first substrate and the second substrate are bonded to each other are planarized by chemical mechanical polishing and then annealed before bonding.

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