Patent Publication Number: US-2023139773-A1

Title: Semiconductor structure and fabrication method thereof

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application claims the priority of Chinese patent application No. 202111264284.1, filed on Oct. 28, 2021, the entirety of which is incorporated herein by reference. 
     FIELD OF THE DISCLOSURE 
     The present disclosure generally relates to the field of semiconductor manufacturing technology and, more particularly, relates to a semiconductor structure and a fabrication method thereof. 
     BACKGROUND 
     For semiconductor integrated circuits, various circuit element structures can be fabricated on a silicon wafer to form integrated circuit (IC) devices with specific electrical functions. The wafer then needs to be diced into a plurality of chips. The dicing process is performed on the scribe line region. 
     With the development of integrated circuits, to maximize the production capacity of various machines, to form circuit element structures with substantially high integration degree and complexity degree, and to perform wafer-level testing on the circuit element structures, alignment marks required for various machines and corresponding pads with various functions, etc., are designed in the scribe line region. Therefore, the metal patterns in the scribe line region are varied and in high density. 
     Meanwhile, to protect various circuit element structures on the silicon wafer, a seal ring is formed on the boundary of the scribe line region, and a passivation layer is formed on the scribe line region. 
     Often, a long and thick metal alignment mark needs to be formed in the front-end-of-line (FEOL), while the metal alignment mark has uneven stress distribution and too large local stress. Therefore, during the dicing process, when dicing the metal alignment mark, a peeling phenomenon of materials tends to occur in the region where the metal alignment mark is located. For example, the metal alignment mark has a long metal brushed problem (long burr), and the passivation layer also tends to have a peeling phenomenon. Because the long brushed metal tends to be in contact with surrounding seal ring and the circuit on the silicon wafer, the risk of electrical failure such as short circuit is easy to occur in the circuit, the circuit tends to have a risk of electrical failure such as short circuit, which leads to poor reliability of the semiconductor structure. The disclosed methods and device structures are directed to solve one or more problems set forth above and other problems. 
     BRIEF SUMMARY OF THE DISCLOSURE 
     One aspect of the present disclosure includes a semiconductor structure. The semiconductor structure includes a substrate, and the substrate includes a scribe line region. The semiconductor structure also includes a device layer over the substrate. The device layer includes multiple devices, an interconnection structure electrically connected to the devices, and a dielectric layer surrounding the devices and the interconnection structure. Further, the device layer includes a passivation layer over the device layer, and an alignment mark in the passivation layer over the scribe line region. The alignment mark includes two or more sub-alignment marks, the two or more sub-alignment marks are arranged along an extension direction of the scribe line region, and adjacent sub-alignment marks of the two or more sub-alignment marks are spaced apart from each other. 
     Optionally, a sub-alignment mark of the two or more sub-alignment marks includes a metal strip. 
     Optionally, a projection of the sub-alignment mark on a surface of the substrate has a rectangle shape. A length direction of the rectangle is parallel to the extension direction of the scribe line region, and a length-to-width ratio of the rectangle is in a range approximately between 1 and 2.4. 
     Optionally, a length of the sub-alignment mark in the extension direction of the scribe line region is in a range approximately between 70 µm and 120 µm, and a minimum distance between the adjacent sub-alignment marks in the extension direction of the scribe line region is approximately 50 µm. 
     Optionally, a width direction of the rectangle is perpendicular to the extension direction of the scribe line region, and a width of the sub-alignment mark is in a range approximately between 50 µm and 70 µm. 
     Optionally, the substrate further includes a plurality of first regions adjacent to the scribe line region, and the scribe line region is located between adjacent first regions of the plurality of first regions. 
     Optionally, the semiconductor structure further includes a seal ring over a border between the scribe line region and the adjacent first regions. 
     Optionally, in a direction perpendicular to a sidewall surface of the seal ring, a distance between the sub-alignment mark and the seal ring is greater than 5 µm. 
     Optionally, in a direction perpendicular to a surface of the substrate, a thickness of the sub-alignment mark is in a range approximately between 3.3 µm and 4 µm. 
     Optionally, the semiconductor structure further includes test keys and metal pads in the passivation layer over the scribe line region. 
     Another aspect of the present disclosure includes a fabrication method of a semiconductor structure. The method includes providing a substrate, where the substrate includes a scribe line region. The method also includes forming a device layer over the substrate. The device layer includes multiple devices, an interconnection structure electrically connected to the devices, and a dielectric layer surrounding the devices and the interconnection structure. Further, the method includes forming a passivation layer over the device layer, and forming an alignment mark in the passivation layer over the scribe line region. The alignment mark includes two or more sub-alignment marks, the two or more sub-alignment marks are arranged along an extension direction of the scribe line region, and adjacent sub-alignment marks of the two or more sub-alignment marks are spaced apart from each other. 
     Optionally, forming the passivation layer and the alignment mark includes: forming a lower passivation layer over the device layer; etching the lower passivation layer over the scribe line region, to from two or more grooves in the lower passivation layer over the scribe line region; forming the two or more sub-alignment marks in the two or more grooves; and forming an upper passivation layer on the lower passivation layer and on surfaces of the two or more sub-alignment marks, where the upper passivation layer and the lower passivation layer form the passivation layer. 
     Optionally, the alignment mark is configured to form a metal interconnection layer in back-end-of-line. 
     Optionally, the substrate further includes a plurality of first regions adjacent to the scribe line region, and the scribe line region is located between adjacent first regions of the plurality of first regions. 
     Optionally, the method further includes performing a dicing process on the scribe line region to form a plurality of mutually independent chips, where each chip includes a first region of the plurality of first regions. 
     Optionally, a sub-alignment mark of the two or more sub-alignment marks includes a metal strip. 
     Optionally, a projection of the sub-alignment mark on a surface of the substrate has a rectangle shape. A length direction of the rectangle is parallel to the extension direction of the scribe line region, a width direction of the rectangle is perpendicular to the extension direction of the scribe line region, and a length-to-width ratio of the rectangle is in a range approximately between 1 and 2.4. 
     Optionally, a length of the sub-alignment mark is in a range approximately between 70 µm and 120 µm. A width of the sub-alignment mark is in a range approximately between 50 µm and 70 µm. A minimum distance between the adjacent sub-alignment marks in the extension direction of the scribe line region is approximately 50 µm. 
     Optionally, in a direction perpendicular to a surface of the substrate, a thickness of the sub-alignment mark is in a range approximately between 3.3 µm and 4 µm. 
     Optionally, the method further includes forming test keys and metal pads in the passivation layer over the scribe line region. 
     The disclosed embodiments may have following beneficial effects. In the disclosed semiconductor structure, the alignment mark in the passivation layer over the scribe line region may include two or more sub-alignment marks, and the two or more sub-alignment marks may be arranged along the extension direction of the scribe line region. In addition, the adjacent sub-alignment marks may be spaced apart from each other. Therefore, the substantially long alignment mark composed of the two or more sub-alignment marks may still satisfy the requirements for long alignment mark in the back-end-of-line (BEOL). In view of this, the short and spaced sub-alignment marks may still have desired uniform stress distribution and small local stress. When subsequently dicing the scribe line region, the peeling phenomenon may be less likely to occur, thereby reducing the risk that the long brushed conductive material is in contact with the devices and interconnection structure over the first region, and improving the reliability of the semiconductor structure. 
     Other aspects of the present disclosure can be understood by those skilled in the art in light of the description, the claims, and the drawings of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS.  1 - 5    illustrate semiconductor structures corresponding to certain stages for forming an exemplary semiconductor structure consistent with various disclosed embodiments of the present disclosure; and 
         FIG.  6    illustrates a flowchart of an exemplary method for forming a semiconductor structure consistent with various disclosed embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to exemplary embodiments of the disclosure, which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or the alike parts. 
     The present disclosure provides a semiconductor structure and a fabrication method of a semiconductor structure. In the disclosed semiconductor structure, an alignment mark in a passivation layer over a scribe line region may include two or more sub-alignment marks, and the two or more sub-alignment marks may be arranged along an extension direction of the scribe line region. Further, adjacent sub-alignment marks may be spaced apart from each other. Therefore, the semiconductor structure may have desired reliability. 
       FIG.  6    illustrates a flowchart of a method for forming a semiconductor structure consistent with various disclosed embodiments of the present disclosure, and  FIGS.  1 - 5    illustrate semiconductor structures corresponding to certain stages of the fabrication method. 
     As shown in  FIG.  6   , at the beginning of the fabrication method, a substrate including a scribe line region may be provided (S 101 ).  FIGS.  1 - 2    illustrate a corresponding semiconductor structure. 
       FIG.  1    illustrates a schematic top view of the structure shown in  FIG.  2   , and  FIG.  2    illustrates a schematic X1-X2 cross-sectional view of the structure shown in  FIG.  1   . Referring to  FIG.  1    and  FIG.  2   , a substrate  100  may be provided. 
     In one embodiment, the substrate  100  may be made of a semiconductor material. In one embodiment, the substrate  100  may be made of a material including silicon. In certain embodiments, the substrate may be made of a material including silicon carbide, silicon germanium, a multi-component semiconductor material composed of Group III-V elements, silicon-on-insulator (SOI), or germanium-on-insulator (GOI), etc. The multi-component semiconductor material composed of Group III-V elements may include InP, GaAs, GaP, InAs, InSb, InGaAs, or InGaAsP, etc. 
     The substrate  100  may include a scribe line region A. The substrate  100  may further include a plurality of first regions B adjacent to the scribe line region A. In one embodiment, the scribe line region A may be located between adjacent first regions B. 
     The scribe line region A may reserve space for the dicing process after forming the semiconductor wafer, to divide the semiconductor wafer into a plurality of chips. After performing the dicing process, each chip may include a device layer subsequently formed on the first region B. 
     For illustrative purposes,  FIG.  1    merely illustrates a portion of the two first regions B, and the scribe line region A between the two first regions B, although more or less portions, and/or more or less regions may be included in  FIG.  1   . 
     Returning to  FIG.  6   , after providing the substrate, a device layer including multiple devices, an interconnection structure electrically connected to the devices, and a dielectric layer surrounding the devices and the interconnection structure may be formed over the substrate (S 102 ).  FIG.  3    illustrates a corresponding semiconductor structure. 
     Referring to  FIG.  3   , a device layer  110  may be formed on the substrate  100 . In one embodiment, the device layer  110  may include multiple devices (not shown in the Figure), an interconnection structure electrically connected to the devices (not shown in the Figure), and a dielectric layer surrounding the devices and the interconnection structure (not shown in the Figure). 
     In one embodiment, the multiple devices may include electronic devices such as transistors, resistors, and capacitors, etc. The multiple devices and the interconnection structure may form an integrated circuit. 
     The dielectric layer may be made of a material including a dielectric material. The dielectric material may include one or more of titanium oxide, zirconium oxide, hafnium oxide, silicon oxide, silicon nitride, silicon carbide, silicon oxy-carbide, silicon oxy-nitride, aluminum oxide, aluminum nitride, silicon nitride carbide, and silicon oxy-carbo-nitride. 
     Returning to  FIG.  6   , after forming the device layer, a passivation layer over the device layer may be formed over the device layer, and an alignment mark may be formed in the passivation layer over the scribe line region (S 103 ).  FIGS.  4 - 5    illustrate a corresponding semiconductor structure. 
       FIG.  4    illustrates a schematic top view of the structure shown in  FIG.  5   , and  FIG.  5    illustrates a schematic X1-X2 cross-sectional view of the structure shown in  FIG.  4   . Referring to  FIG.  4    and  FIG.  5   , a passivation layer  120  may be formed on the device layer  110 , and an alignment mark  130  may be formed in the passivation layer  120  over the scribe line region A. The alignment mark  130  may include two or more sub-alignment marks  131 , and the two or more sub-alignment marks  131  may be arranged along an extension direction of the scribe line region A. Further, the adjacent sub-alignment marks  131  may be spaced apart from each other. 
     Projections of the two or more sub-alignment marks  131  of the alignment mark  130  on the surface of the substrate  100  may be located within a range of the scribe line region A. It should be understood that the extension direction of the scribe line region A may refer to an extension direction of the portion of the scribe line region A where the projections are located. In addition, the alignment mark  130  may be used for alignment with a last layer in the back-end-of-line (BEOL). Therefore, a thickness H of the sub-alignment mark  131  in a direction perpendicular to the surface of the substrate  100  may often be substantially thick. 
     The alignment mark  130  in the passivation layer  120  over the scribe line region A may include two or more sub-alignment marks  131 , and the two or more sub-alignment marks  131  may be arranged along the extension direction of the scribe line region A. In addition, the adjacent sub-alignment marks  131  may be spaced apart from each other. Therefore, the substantially long alignment mark  130  composed of the two or more sub-alignment marks  131   may still satisfy the requirements for long alignment mark in the back-end-of-line (BEOL). In view of this, even if the thickness H is substantially thick, the short and spaced sub-alignment marks  131  may still have desired uniform stress distribution and small local stress. When subsequently dicing the scribe line region A, the peeling phenomenon may be less likely to occur, thereby reducing the risk that the long brushed conductive material is in contact with the devices and interconnection structure over the first region B, and improving the reliability of the semiconductor structure. 
     It should be noted that for illustrative purposes,  FIG.  4    may merely schematically illustrate two sub-alignment marks  131  with the same projected shape. In practical applications, the two or more sub-alignment marks  131  may include two sub-alignment marks  131  or a plurality of sub-alignment marks  131 . Further, the projected shape of each sub-alignment mark  131  on the surface of the substrate  100  may be the same or different. 
     In one embodiment, the quantity of sub-alignment marks  131  may be two, to better reduce the difficulty and complexity of the process. In one embodiment, the projected shape of each sub-alignment mark  131  may be the same, to better reduce the difficulty and complexity of the process. 
     In one embodiment, in the direction perpendicular to the surface of the substrate, the thickness H of the sub-alignment mark  131  may be in a range approximately between 3.3 µm and 4 µm. 
     In one embodiment, the alignment mark  130  may be configured to form a metal interconnection layer in the back-end-of-line. 
     In one embodiment, the sub-alignment mark  131  may include a metal strip. The sub-alignment mark  131  may be made of a material including a conductive material such as copper, aluminum, gold, and silver. 
     In one embodiment, the projection of the sub-alignment mark  131  on the surface of the substrate  100  may have a rectangle shape. A length direction of the rectangle may be parallel to the extension direction of the scribe line region A, and a width direction of the rectangle may be perpendicular to the extension direction of the scribe line region A. At the same time, a length-to-width ratio of the rectangle may be in a range approximately between 1 and 2.4, in other words, 1≤(W1/W2)≤2.4, where W1 (as shown in  FIG.  4   ) may be the length of the rectangle, and W2 (as shown in  FIG.  4   ) may be the width of the rectangle. 
     To form the alignment mark  130  with a substantially long total length W (as shown in  FIG.  4   ) using two or more sub-alignment marks  131 , if the length-to-width ratio of the sub-alignment mark is too small, a substantially large amount of sub-alignment marks  131  may need to be formed, which may lead to a substantially large process difficulty and complexity; if the length-to-width ratio of the sub-alignment mark is too large, when subsequently dicing the scribe line region A, the ability to improve the peeling phenomenon may be limited. Therefore, by choosing a suitable length-to-width ratio of the rectangle, in other words, the length-to-width ratio of the rectangle may be in a range approximately between 1 and 2.4, such that the peeling phenomenon may be effectively improved while reducing the process difficulty and complexity. 
     In one embodiment, the length (equivalent to the length W1) of the sub-alignment mark  131  in the extension direction of the scribe line region A may be in a range approximately between 70 µm and 120 µm. A minimum distance G1 (as shown in  FIG.  4   ) between the adjacent sub-alignment marks  131  in the extension direction of the scribe line region A may be approximately 50 µm, to effectively reduce the risk of peeling phenomenon. 
     In one embodiment, the width of the sub-alignment mark  131  (equivalent to the width W2) may be in a range approximately between 50 µm and 70 µm, to effectively reduce the risk of peeling phenomenon. 
     In one embodiment, forming the passivation layer  120  and the alignment mark  130  may include: forming a lower passivation layer  121  on the device layer  110 ; etching the lower passivation layer  121  over the scribe line region A, to from two or more grooves (not shown in the Figure) in the lower passivation layer  121  over the scribe line region A; forming the two or more sub-alignment marks  131  in the two or more grooves; and forming an upper passivation layer  122  on the lower passivation layer  121  and the surfaces of the two or more sub-alignment marks  131 . The upper passivation layer  122  and the lower passivation layer  121  may form the passivation layer  120 . 
     In one embodiment, forming the lower passivation layer  121  may include a chemical vapor deposition process, a physical vapor deposition process, a fluid chemical vapor deposition process, or a spin coating process, etc. Forming the upper passivation layer  122  may include a chemical vapor deposition process, a physical vapor deposition process, a fluid chemical vapor deposition process, or a spin coating process, etc. 
     In one embodiment, etching the lower passivation layer  121  over the scribe line region A may include at least one of a dry etching process and a wet etching process. 
     In one embodiment, the passivation layer  120  may be made of a material including a dielectric material, and the dielectric material may include one or more of titanium oxide, zirconium oxide, hafnium oxide, silicon oxide, silicon nitride, silicon carbide, silicon oxy-carbide, silicon oxy-nitride, aluminum oxide, aluminum nitride, silicon nitride carbide, and silicon oxy-carbo-nitride. 
     In one embodiment, forming the sub-alignment mark  131  in the groove may include: forming a sub-alignment mark material layer (not shown in the Figure) in the groove and on the surface of the lower passivation layer  121 ; and planarizing the sub-alignment mark material layer until the surface of the lower passivation layer  121  is exposed, to form the sub-alignment mark  131 . 
     In one embodiment, forming the sub-alignment mark material layer may include a chemical vapor deposition process, or a metal electroplating process, etc. Planarizing the sub-alignment mark material layer may include a chemical mechanical polishing process. 
     It should be noted that for illustrative purposes, the upper passivation layer  122  may not be shown in  FIG.  4   . 
     In one embodiment, in the process of forming the device layer  110 , the passivation layer  120  and the alignment mark  130 , a seal ring  140  may be formed in the device layer  110  and the passivation layer  120  over the border between the scribe line region A and the first region B. 
     The seal ring  140  may be configured to protect the integrated circuits over the first region B, to better reduce the risk of damage to the integrated circuits over the first region B. 
     In one embodiment, in a direction perpendicular to a sidewall surface of the seal ring  140 , a distance G2 (as shown in  FIG.  4   ) between the sub-alignment mark  131  and the seal ring  140  may be greater than 5 µm. The substantially large distance G2 between the sub-alignment mark  131  and the seal ring  140  may reduce the risk that burrs formed after dicing the sub-alignment marks  131  contacts the seal ring  140 , and may further reduce the risk of electrical failure such as short circuit occurred in the circuit, to further improve the reliability of the semiconductor structure. 
     In one embodiment, in the process of forming the passivation layer  120  and the alignment mark  130 , test keys (not shown) and metal pads (not shown) may also be formed in the passivation layer  120  over the scribe line region A. The test keys and metal pads are at least used for wafer level testing. 
     In various embodiments, to inspect electrical characteristics of the semiconductor device, a test probe may be used to connect to the semiconductor device after the semiconductor device is formed. The test probe may include test pins, and the semiconductor device may include a test key. The test key may include metal pads corresponding to the test pins of the test probe. After the test probe is moved to contact with the test key, the test pins may be aligned with the metal pads formed on the semiconductor device to make electrical connections. To effectively inspect the electrical characteristics of the semiconductor device and avoid damaging the semiconductor, each test pin of the test probe may provide desirable electrical contact with a corresponding metal pad of the test key on the semiconductor device. 
     In one embodiment, after forming the passivation layer  120  and the alignment mark  130 , a dicing process may be performed on the scribe line region A to form a plurality of mutually independent chips (not shown), and each chip may include the first region B. 
     Correspondingly, the present disclosure also provides a semiconductor structure. Referring to  FIGS.  4 - 5   , the semiconductor structure may include a substrate  100  including a scribe line region A; a device layer  110  on the substrate  100 ; a passivation layer  120  on the device layer  110 ; and an alignment mark  130  in the passivation layer  120  over the scribe line region A. The alignment mark  130  may include two or more sub-alignment marks  131 , and the two or more sub-alignment marks  131  may be arranged along an extension direction of the scribe line region A. Further, adjacent sub-alignment marks  131  may be spaced apart from each other. 
     In one embodiment, the substrate  100  may further include a plurality of first regions B adjacent to the scribe line region A. In one embodiment, the scribe line region A may be located between adjacent first regions B. 
     The scribe line region A may reserve space for the dicing process after forming the semiconductor wafer, to divide the semiconductor wafer into a plurality of chips. After performing the dicing process, each chip may include the device layer  110  formed on the first region B. 
     The device layer  110  may include multiple devices (not shown in the Figure), an interconnection structure electrically connected to the devices (not shown in the Figure), and a dielectric layer surrounding the devices and the interconnection structure (not shown in the Figure). 
     In one embodiment, the multiple devices may include electronic devices such as transistors, resistors, and capacitors, etc. The multiple devices and the interconnection structure may form an integrated circuit. 
     Projections of the two or more sub-alignment marks  131  of the alignment mark  130  on the surface of the substrate  100  may be located within a range of the scribe line region A. It should be understood that the extension direction of the scribe line region A may refer to an extension direction of the portion of the scribe line region A where the projections are located. In addition, the alignment mark  130  may be used for alignment with a last layer in the back-end-of-line (BEOL). Therefore, a thickness H of the sub-alignment mark  131  in the direction perpendicular to the surface of the substrate  100  may often be substantially thick. 
     The alignment mark  130  in the passivation layer  120  over the scribe line region A may include two or more sub-alignment marks  131 , and the two or more sub-alignment marks  131  may be arranged along the extension direction of the scribe line region A. In addition, the adjacent sub-alignment marks  131  may be spaced apart from each other. Therefore, the substantially long alignment mark  130  composed of the two or more sub-alignment marks  131  may still satisfy the requirements for long alignment mark in the back-end-of-line (BEOL). In view of this, even if the thickness H is substantially thick, the short and spaced sub-alignment marks  131  may still have desired uniform stress distribution and small local stress. When subsequently dicing the scribe line region A, the peeling phenomenon may be less likely to occur, thereby reducing the risk that the long brushed conductive material is in contact with the devices and interconnection structure over the first region B, and improving the reliability of the semiconductor structure. 
     It should be noted that the two or more sub-alignment marks  131  may include two sub-alignment marks  131  or a plurality of sub-alignment marks  131 . Further, the projected shape of each sub-alignment mark  131  on the surface of the substrate  100  may be the same or different. 
     In one embodiment, the quantity of sub-alignment marks  131  may be two, to better reduce the difficulty and complexity of the process. In one embodiment, the projected shape of each sub-alignment mark  131  may be the same, to better reduce the difficulty and complexity of the process. 
     In one embodiment, in the direction perpendicular to the surface of the substrate, the thickness H of the sub-alignment mark  131  may be in a range approximately between 3.3 µm and 4 µm. 
     In one embodiment, the alignment mark  130  may be configured to form a metal interconnection layer in the back-end-of-line (BEOL). 
     In one embodiment, the sub-alignment mark  131  may include a metal strip. The sub-alignment mark  131  may be made of a material including a conductive material such as copper, aluminum, gold, and silver. 
     In one embodiment, the projection of the sub-alignment mark  131  on the surface of the substrate  100  may have a rectangle shape. A length direction of the rectangle may be parallel to the extension direction of the scribe line region A, and a width direction of the rectangle may be perpendicular to the extension direction of the scribe line region A. At the same time, a length-to-width ratio of the rectangle may be in a range approximately between 1 and 2.4, in other words, 1≤(W1/W2)≤2.4, where W1 (as shown in  FIG.  4   ) may be the length of the rectangle, and W2 (as shown in  FIG.  4   ) may be the width of the rectangle. 
     To form the substantially long alignment mark  130  using two or more sub-alignment marks  131 , if the length-to-width ratio of the sub-alignment mark  131  is too small, a substantially large amount of sub-alignment marks  131  may need to be formed, which may lead to a substantially large process difficulty and complexity; if the length-to-width ratio of the sub-alignment mark  131  is too large, when subsequently dicing the scribe line region A, the ability to improve the peeling phenomenon may be limited. Therefore, by choosing a suitable length-to-width ratio of the rectangle, in other words, the length-to-width ratio of the rectangle may be in a range approximately between 1 and 2.4, such that the peeling phenomenon may be effectively improved while reducing the process difficulty and complexity. 
     In one embodiment, the length (equivalent to the length W1) of the sub-alignment mark  131  in the extension direction of the scribe line region A may be in a range approximately between 70 µm and 120 µm. A minimum distance G1 (as shown in  FIG.  4   ) between the adjacent sub-alignment marks  131  in the extension direction of the scribe line region A may be approximately 50 µm, to effectively reduce the risk of peeling phenomenon. 
     In one embodiment, the width of the sub-alignment mark  131  (equivalent to the width W2) may be in a range approximately between 50 µm and 70 µm, to effectively reduce the risk of peeling phenomenon. 
     In one embodiment, the passivation layer  120  may include a lower passivation layer  121 , and an upper passivation layer  122  on the lower passivation layer  121  and the surfaces of the two or more sub-alignment marks  131 . 
     In one embodiment, the passivation layer  120  may be made of a material including a dielectric material, and the dielectric material may include one or more of titanium oxide, zirconium oxide, hafnium oxide, silicon oxide, silicon nitride, silicon carbide, silicon oxy-carbide, silicon oxy-nitride, aluminum oxide, aluminum nitride, silicon nitride carbide, and silicon oxy-carbo-nitride. 
     The dielectric layer of the device layer  110  may be made of a material including a dielectric material. The dielectric material may include one or more of titanium oxide, zirconium oxide, hafnium oxide, silicon oxide, silicon nitride, silicon carbide, silicon oxy-carbide, silicon oxy-nitride, aluminum oxide, aluminum nitride, silicon nitride carbide, and silicon oxy-carbo-nitride. 
     In one embodiment, the semiconductor structure may also include a seal ring  140  over the border between the scribe line region A and the first region B. The seal ring  140  may be configured to protect the integrated circuits over the first region B, to better reduce the risk of damage to the integrated circuits over the first region B. 
     In one embodiment, in a direction perpendicular to a sidewall surface of the seal ring  140 , a distance G2 (as shown in  FIG.  4   ) between the sub-alignment mark  131  and the seal ring  140  may be greater than 5 µm. The substantially large distance G2 between the sub-alignment mark  131  and the seal ring  140  may reduce the risk that burrs formed after dicing the sub-alignment marks  131  contacts the seal ring  140 , and may further reduce the risk of electrical failure such as short circuit occurred in the circuit, to further improve the reliability of the semiconductor structure. 
     In one embodiment, the semiconductor structure may further include test keys (not shown) and metal pads (not shown) in the passivation layer  120  over the scribe line region A. 
     In various embodiments, to inspect electrical characteristics of the semiconductor device, a test probe may be used to connect to the semiconductor device after the semiconductor device is formed. The test probe may include test pins, and the semiconductor device may include a test key. The test key may include metal pads corresponding to the test pins of the test probe. After the test probe is moved to contact with the test key, the test pins may be aligned with the metal pads formed on the semiconductor device to make electrical connections. To effectively inspect the electrical characteristics of the semiconductor device and avoid damaging the semiconductor, each test pin of the test probe may provide desirable electrical contact with a corresponding metal pad of the test key on the semiconductor device. 
     The disclosed embodiments may have following beneficial effects. In the disclosed semiconductor structure, the alignment mark in the passivation layer over the scribe line region may include two or more sub-alignment marks, and the two or more sub-alignment marks may be arranged along the extension direction of the scribe line region. In addition, the adjacent sub-alignment marks may be spaced apart from each other. Therefore, the substantially long alignment mark composed of the two or more sub-alignment marks may still satisfy the requirements for long alignment mark in the back-end-of-line (BEOL). In view of this, the short and spaced sub-alignment marks may still have desired uniform stress distribution and small local stress. When subsequently dicing the scribe line region, the peeling phenomenon may be less likely to occur, thereby reducing the risk that the long brushed conductive material is in contact with the devices and interconnection structure over the first region, and improving the reliability of the semiconductor structure. 
     The above detailed descriptions only illustrate certain exemplary embodiments of the present disclosure, and are not intended to limit the scope of the present disclosure. Those skilled in the art can understand the specification as whole and technical features in the various embodiments can be combined into other embodiments understandable to those persons of ordinary skill in the art. Any equivalent or modification thereof, without departing from the spirit and principle of the present disclosure, falls within the true scope of the present disclosure.