Metal laminated structure and preparation method thereof

Abstract

The invention discloses a metal laminated structure and a preparation method thereof. The metal laminated structure comprises at least two metal layers, wherein the bottom surfaces of the two metal layers are positioned on the same substrate; wherein one metal layer is provided with a groove structure, the other metal layer is provided with an extending structure, and the extending structure is embedded in the groove structure to form a planar metal laminated structure. Through the scheme of the embodiment of the invention, the metal laminated structure can be optimized, the traditional metal laminated structure is converted into the planar metal laminated structure, the critical dimension deviation caused by the step height is eliminated, and the reliability of the device is improved. And the risks that the second metal layer at the overlapped part of the metal laminated structure is broken due to the step height and the second metal layer is attached to the first metal layer and cracks are reduced.

Description

Technical Field

[0001] The present application generally relates to the field of semiconductor technology. More specifically, the present application relates to a metal stacked structure and a method for preparing the metal stacked structure. Background Art

[0002] Some existing semiconductor processes involve a special chip manufacturing technology - a double-layer metal stacking process, which is a process technology used to achieve interconnection between different metal layers. It aims to form an interconnection structure inside the chip through steps such as metal layer deposition, photolithography, and etching.

[0003] In the existing double-layer metal stacking process, when the first metal layer is completed and the second metal layer is etched, due to the step height caused by the thickness of the first metal layer, the second metal layer is prone to defocusing in the area where the metal stacking structure is formed, which will cause the critical dimension at the top of the metal stacking structure to be smaller.

[0004] Currently, this type of deviation cannot be compensated or corrected individually by optical proximity correction (OPC) technology. Due to the variation in metal layer thickness and step height, OPC technology can improve this problem but cannot completely solve this defect, which will reduce the yield rate. In addition, the height difference after the first metal layer is formed in the prior art will also introduce the problem of the second metal layer being disconnected or cracked on the side of the stacking of the metal stacking structure formed with the first metal layer, which will also reduce the product yield rate and make the product unable to be mass-produced.

[0005] In view of this, there is an urgent need to provide a metal stacking process solution to optimize the metal stacking structure and eliminate the uncontrollable problem of the key dimensions of the top surface of the metal stacking structure. At the same time, it can also solve the risk of the second metal layer at the overlapping part of the metal stacking structure being disconnected and cracked from the first metal layer due to the step height. Summary of the invention

[0006] In order to at least solve one or more of the technical problems mentioned above, the present application proposes a metal stacking process solution in multiple aspects.

[0007] In a first aspect, the present application provides a metal stack structure comprising: at least two metal layers, the bottom surfaces of the two metal layers are located on the same substrate; one of the metal layers has a groove structure, and the other metal layer has an extension structure, and the extension structure is embedded in the groove structure to form a planar metal stack structure.

[0008] In some embodiments, at least two metal layers include: a first metal layer and a second metal layer; the first metal layer includes: a linear conductive portion and at least two protruding conductive portions, the protruding conductive portions are connected to the linear conductive portion to form a groove structure, the protruding conductive portions are the groove walls of the groove structure, and the linear conductive portion is the groove bottom of the groove structure; the second metal layer includes: a strip-type conductive portion and an embedded conductive portion extending from one side of the strip-type conductive portion, wherein the embedded conductive portion is embedded in the groove structure and connected to the linear conductive portion.

[0009] In some embodiments, at least two metal layers include: a first metal layer and a second metal layer; the second metal layer includes: a linear conductive portion and at least two protruding conductive portions, wherein the protruding conductive portion is connected to the linear conductive portion to form a groove structure, the protruding conductive portion is the groove wall of the groove structure, and the linear conductive portion is the groove bottom of the groove structure; the first metal layer includes: a strip-type conductive portion, and part of the strip-type conductive portion is embedded in the groove structure.

[0010] In some embodiments, in the first metal layer, the protruding conductive portion is a conductive portion extending along the length direction of the linear conductive portion, and the protruding conductive portion is perpendicular to the linear conductive portion to form a caliper-shaped or U-shaped groove structure; in the second metal layer, the embedded conductive portion is perpendicular to the strip-shaped conductive portion.

[0011] In some embodiments, the outwardly protruding conductive portion is a conductive portion extending toward the same side of the linear conductive portion, and the outwardly protruding conductive portion is perpendicular to the linear conductive portion to form an F-shaped groove structure.

[0012] In some embodiments, the top surface of the second metal layer has an epitaxial surface compared to the bottom surface thereof, and the epitaxial surface is located at the bottom of the groove structure and covers a portion of the first metal layer.

[0013] In some embodiments, the metal stack structure further includes: a barrier layer; the barrier layer covers the surface of the first metal layer and the junction between the first metal layer and the second metal layer to function as an intermediate dielectric layer of the metal stack structure.

[0014] In a second aspect, the present application provides a method for preparing a metal stacked structure, including: preparing a first metal layer having a first structure; depositing a second metal layer on the first metal layer; coating a photoresist on the second metal layer; developing and curing the photoresist in a target area; and etching to form a second metal layer having a second structure using a photolithography process, so that the first metal layer and the second metal layer form a planar metal stacked structure; wherein, when the first structure is a groove structure, the target area includes an area embedded in the groove structure and an area extending along an opening direction of the groove structure, and the second structure includes an extension structure embedded in the groove structure; when the first structure is an extension structure, the target area includes a groove-shaped area semi-surrounding the extension structure, and the second structure includes a groove structure embedded in the extension structure.

[0015] In some embodiments, preparing a first metal layer having a first structure includes: depositing the first metal layer on a substrate; coating a photoresist on the first metal layer; developing and curing the photoresist in a preset area; and etching using a photolithography process to form a first metal layer having a first structure; wherein, when the first structure is a groove structure, the preset area includes a linear area and at least two protruding areas, the linear area and the protruding area are connected to form a groove shape, the linear area is the groove bottom, the protruding area is the groove wall, the first metal layer includes a linear conductive portion located in the linear area and a protruding conductive portion located in the protruding area, and the target area includes a stripe type area and an interlocking area extending from the strip-type area, the interlocking area is interlocked in the preset area, and the second metal layer includes a strip-type conductive portion located in the strip-type area and an interlocking conductive portion located in the interlocking area; when the first structure is an extended structure, the preset area includes the strip-type area, the first metal layer includes a strip-type conductive portion located in the strip-type area, the target area includes a linear area and at least two protruding areas, the linear area and the protruding area are connected and are in the shape of a groove that semi-surrounds the preset area, the linear area is the groove bottom, the protruding area is the groove wall, and the second metal layer includes a linear conductive portion located in the linear area and a protruding conductive portion located in the protruding area.

[0016] In some embodiments, the target area also includes: an area located at the bottom of the groove structure and covering a portion of the top surface of the first metal layer.

[0017] Through the metal stacked structure provided as above, the embodiment of the present application designs one metal layer in the double metal layer to have a groove structure, and designs the other metal layer to have an extended structure, and the extended structure extends into the groove structure and is interconnected with the adjacent metal layer in an interlocking manner, thereby converting the three-dimensional metal stacked structure of the traditional stacking method into a planar metal stacked structure, eliminating the final product defects caused by the step height of the first metal layer in the existing double-layer metal stacking process. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] By reading the detailed description below with reference to the accompanying drawings, the above and other purposes, features and advantages of the exemplary embodiments of the present application will become easy to understand. In the accompanying drawings, several embodiments of the present application are shown in an exemplary and non-limiting manner, and the same or corresponding reference numerals represent the same or corresponding parts, wherein: Figure 1 A schematic cross-sectional view of a metal stack structure prepared by an existing metal stack process is shown; Figure 2 An electron microscope image of a metal stack structure prepared by an existing metal stack process is shown; Figure 3 An exemplary top view of a metal stack structure according to some embodiments of the present application is shown; Figure 4 Shows Figure 3 AA of the metal stack structure shown Sectional drawing; Figure 5 Showing cross-sectional views of metal stacked structures of other embodiments of the present application; Figure 6 illustrative top views of metal stacked structures according to other embodiments of the present application are shown; Figure 7 Shows Figure 6 BB of the metal stack structure shown Sectional drawing; Figure 8 Showing cross-sectional views of metal stacked structures of other embodiments of the present application; Fig. 9 An exemplary flow chart showing a method for preparing a metal laminate structure according to some embodiments of the present application; Fig.10 An exemplary flow chart showing a method for preparing a first metal layer according to some embodiments of the present application; Fig.11 A schematic diagram showing a preparation process of a metal laminate structure according to some embodiments of the present application; Fig.12 Schematic diagram showing the preparation process of the metal stacked structure of other embodiments of the present application; Description of reference numerals: 11 - first metal layer; 12 - second metal layer; 101 - linear conductive portion; 102 - protruding conductive portion; 103 - strip-shaped conductive portion; 104 - embedded conductive portion; 13 - substrate; 14 - barrier layer. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0020] It should be understood that the terms "include" and "comprising" used in the specification and claims of the present application indicate the presence of described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or collections thereof.

[0021] It should also be understood that the terms used in this application specification are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in this application specification and claims, unless the context clearly indicates otherwise, the singular forms of "a", "an" and "the" are intended to include plural forms. It should also be further understood that the term "and / or" used in this application specification and claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes these combinations.

[0022] As used in this specification and claims, the term "if" can be interpreted as "when" or "upon" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrases "if it is determined" or "if [described condition or event] is detected" can be interpreted as meaning "upon determination" or "in response to determining" or "upon detection of [described condition or event]" or "in response to detecting [described condition or event]," depending on the context.

[0023] The specific implementation of the present application is described in detail below with reference to the accompanying drawings.

[0024] Exemplary application scenarios The metal stacking structure is composed of a very thin insulating layer or normal conductor sandwiched between two superconductors. This thin layer is the barrier layer in the semiconductor structure. The metal stacking process plays a key role in the preparation of the metal stacking structure, which involves the precise control and stacking of superconducting materials and barrier layers.

[0025] Some existing semiconductor processes involve a special chip manufacturing technology - a double-layer metal stacking process, which is a process technology used to achieve interconnection between different metal layers. It aims to form an interconnection structure inside the chip through steps such as metal layer deposition, photolithography, and etching.

[0026] Figure 1 shows a schematic cross-sectional view of a metal stack structure prepared by an existing metal stack process, Figure 2 An electron microscope image of a metal stack structure prepared by an existing metal stack process is shown. Figure 1As shown, after the first metal layer is completed and the second metal layer is etched in the existing metal stacking process, a step height difference will be generated at the position where the metal layers overlap, which will cause the focusing depth of the light source used in the photolithography process to produce an error at the overlap, resulting in the problem of defocusing. The defocusing phenomenon will further cause the critical dimension (CD, Critical Dimension) of the top line width of the formed metal stacking structure to be too small. Although the OPC technology can improve this problem, it cannot completely solve this defect. This defect will reduce the yield rate. In addition, the height difference after the first metal layer is formed in the prior art will also introduce the problem of the second metal layer being disconnected or cracked on the side of the stacking of the metal stacking structure formed with the first metal layer, which will also reduce the product yield and cause the product to be unable to be mass-produced.

[0027] Exemplary Application Scenarios In view of this, an embodiment of the present application provides a metal stacking process solution, which, through the mutual cooperation of a groove structure and an extended structure, embeds and interconnects two metal layers on the same plane, thereby converting a traditional metal stacking structure into a planar metal stacking structure and eliminating the CD deviation caused by the step height.

[0028] Figure 3 An exemplary top view of a metal stacked structure according to some embodiments of the present application is shown. Figure 4 Shows Figure 3 AA of the metal stack structure shown Sectional drawing, Figure 6 illustrative top views of metal stacked structures of other embodiments of the present application are shown, Figure 7 Shows Figure 6 BB of the metal stack structure shown Sectional view.

[0029] See also Figure 3 or Figure 6 The metal stacked structure in the embodiment of the present application includes at least two metal layers, the bottom surfaces of the two metal layers are located on the same substrate, one metal layer has a groove structure, and the other metal layer has an extension structure, and the extension structure is embedded in the groove structure to form a planar metal stacked structure.

[0030] As an example, the material of the metal layer may be aluminum or other metal materials, and the substrate may be a silicon substrate.

[0031] For the convenience of description, we refer to the metal layer prepared first on the substrate 13 as the first metal layer 11 and the metal layer prepared later as the second metal layer 12 according to the preparation order. That is to say, the at least two metal layers include: the first metal layer 11 and the second metal layer 12.

[0032] like Figure 3and Figure 4 As shown, the first metal layer 11 has a groove structure, and the first metal layer 11 is caliper-shaped as a whole. A part of the second metal layer 12 extends from one side of the other part and is embedded in the groove structure of the first metal layer 11, so that the first metal layer 11 and the second metal layer 12 are transformed from overlapping in the vertical direction to connecting in the horizontal direction, and the formed metal laminated structure is transformed into a planar junction due to the traditional stacking junction. It should be noted that the vertical direction refers to the direction perpendicular to the substrate, and the horizontal direction refers to the direction parallel to the substrate.

[0033] The following further combines Figure 3 and Figure 4 The structure of the planar metal stacked structure is described below. Figure 3 As shown, the first metal layer is a metal layer with a groove structure, and the groove structure can be formed by the linear conductive part 101 and the protruding conductive part 102 in the first metal layer 11. In other words, the first metal layer 11 includes: a linear conductive part 101 and at least two protruding conductive parts 102, the linear conductive part 101 refers to Figure 3 The conductive areas of the first metal layer 11 located at the leftmost and rightmost sides of the substrate 13, the two protruding conductive portions 102 refer to Figure 3 The conductive areas are respectively connected to the linear conductive part 101 and isolated from each other. In this embodiment, the protruding conductive part 102 is connected to the linear conductive part 101 to form a groove structure. The protruding conductive part 102 is the groove wall of the groove structure, and the linear conductive part 101 is the groove bottom of the groove structure.

[0034] It should be noted that due to Figure 3 and Figure 4 The schematic diagram of the partial structure of the semiconductor product is shown. Therefore, in the actual product, the linear conductive portion 101 may not be located at the leftmost or rightmost side of the substrate 13. The description of the position and direction of the linear conductive portion 101 here is only for the convenience of indication. Figure 3 The linear conductive portion 101 is provided so that those skilled in the art can understand the solution of the embodiment of the present application.

[0035] It needs to be further explained that Figure 3 and Figure 4 What is shown is a schematic diagram of a partial structure of a semiconductor product. In an actual product, the number of the protruding conductive parts 102 may not be limited to two, and the first metal layer 11 may have multiple protruding conductive parts 102 to form multiple groove structures.

[0036] Matching the structure of the first metal layer 11, the second metal layer 12 includes: a strip-shaped conductive portion 103 and an embedded conductive portion 104 extending from one side of the strip-shaped conductive portion 103, wherein the embedded conductive portion 104 is embedded in the groove structure of the first metal layer 11 and connected to the linear conductive portion 101 in the first metal layer 11. Figure 3 As shown, the side walls of the embedded conductive portion 104 in the second metal layer 12 are respectively connected to the groove bottom and the groove wall of the groove structure.

[0037] In the conventional metal stacking process, the strip-shaped conductive portion 103 of the second metal layer 12 needs to overlap above the linear conductive portion 101 of the first metal layer 11, resulting in a step height at the overlap, and thus the focusing depth of the light during etching of the second metal layer 12. In this embodiment, a groove structure is formed by the protruding conductive portion 102 connected to the linear conductive portion 101, and an extended structure is formed by the embedded conductive portion 104 extending from one side of the strip-shaped conductive portion 103, so that the metal stacking structure originally formed in a stacking manner is converted into a planar metal stacking structure formed in an embedded manner, thereby eliminating the defocusing phenomenon caused by the step height.

[0038] In a metal stack structure, the metal lines in two adjacent metal layers are designed to be perpendicular to each other for reasons such as reducing crosstalk, electromagnetic interference, and signal transmission loss. In order to optimize signal integrity, reduce crosstalk and electromagnetic interference, and control line impedance, in some embodiments, such as Figure 3 As shown, the protruding conductive portion 102 in the first metal layer 11 is a conductive portion extending along the length direction of the linear conductive portion 101, and the protruding conductive portion 102 is perpendicular to the linear conductive portion 101 to form a caliper-shaped or U-shaped groove structure. In other words, in the groove structure, the groove wall is perpendicular to the groove bottom. Correspondingly, in the second metal layer 12, the embedded conductive portion 104 is perpendicular to the strip-shaped conductive portion 103.

[0039] It should be noted that the above-mentioned vertical design between the conductive parts is to optimize the signal transmission quality in the metal stacked structure. In other embodiments, the protruding conductive part 102 may also form a certain angle with the linear conductive part 101. For example, the protruding conductive part 102 may form a Y-shaped or Y-shaped groove structure with the linear conductive part 101. Correspondingly, the end of the embedded conductive part 104 that is not connected to the strip-type conductive part 103 is triangular in shape to be embedded in the fork of the Y.

[0040] exist Figure 3 and Figure 4 In the illustrated embodiment, the first metal layer is a metal layer with a groove structure, and the second metal layer is a metal layer with an extension structure. In other embodiments, the second metal layer may have a groove structure, and the first metal layer may have an extension structure, and this case is described below.

[0041] like Figure 6 and Figure 7 As shown, the second metal layer 12 includes: a linear conductive part 101 and at least two protruding conductive parts 102, wherein the protruding conductive part 102 is connected to the linear conductive part 101 to form a groove structure, the protruding conductive part 102 is the groove wall of the groove structure, and the linear conductive part 101 is the groove bottom of the groove structure. At this time, the first metal layer 11 includes: a strip-shaped conductive part 103, and part of the strip-shaped conductive part 103 is embedded in the groove structure to complete the interconnection.

[0042] It should be noted that due to Figure 6 and Figure 7 What is shown is a schematic diagram of the partial structure of a semiconductor product, which only shows two planar metal stacked structures located on the left and right sides of the substrate respectively. In fact, the second metal layer 12 may include multiple protruding conductive parts 102 to form multiple groove structures, and the first metal layer 11 may also include multiple strip-type conductive parts 103 and be respectively embedded in the multiple groove structures.

[0043] In some embodiments, the line width of the portion of the strip-shaped conductive portion 103 embedded in the groove structure is the same as the line width of other portions. In this case, the two portions can be directly regarded as a whole, both of which are the strip-shaped conductive portion 103. In other embodiments, the line width of the portion of the strip-shaped conductive portion 103 embedded in the groove structure may be different from the line width of other portions. In this case, reference can also be made to Figure 3 , the interlocking portion is considered to be an interlocking conductive portion extending from the main body portion, and the main body portion is regarded as a strip-type conductive portion.

[0044] Similar to the previous embodiment, for the sake of signal transmission quality in the metal stack structure, in the second metal layer 12, the protruding conductive portion 102 is a conductive portion extending toward the same side of the linear conductive portion 101, and the protruding conductive portion 102 is perpendicular to the linear conductive portion 101 to form an F-shaped groove structure, and the strip-type conductive portion 103 in the first metal layer 11 is embedded in the opening of the F-shaped groove structure.

[0045] It should be noted that, similar to the embodiment in which the first metal layer has a groove structure, in other embodiments, the protruding conductive portion 102 may also form a certain angle with the linear conductive portion 101 .

[0046] The above embodiments introduce an optimized metal stack structure, which can eliminate the defocusing problem existing in the development process when etching the second metal layer by converting the stacked metal stack structure into a planar metal stack structure.

[0047] In some embodiments of the present application, further designs are made for the above-mentioned development process, so as to reserve a buffer space for etching the second metal layer. Specifically, no matter the second metal layer 12 has a groove structure or an extended structure, the top surface of the second metal layer 12 has an epitaxial surface compared to its bottom surface, and the epitaxial surface is located at the bottom of the groove structure and covers part of the first metal layer.

[0048] like Figure 4 As shown, at the position where the first metal layer 11 and the second metal layer 12 are connected, there is an epitaxial surface on the top of the embedded conductive part 104 in the second metal layer 12, which covers at least part of the top surface of the linear conductive part 101 of the first metal layer 11, and can also cover part of the top surface of the protruding conductive part 102 of the first metal layer 11. Figure 7 As shown, at the position where the first metal layer 11 and the second metal layer 12 are connected, there is an epitaxial surface on the top of the linear conductive part 101 and / or the protruding conductive part 102 in the second metal layer 12, which covers part of the top surface of the strip conductive part 103 of the first metal layer 11. This epitaxial surface design can make the area and electrical performance of the planar metal stacked structure better and better meet the use requirements.

[0049] Furthermore, a barrier layer 14 needs to be provided between the first metal layer 11 and the second metal layer 12. The barrier layer 14 acts as an intermediate dielectric layer of the metal stack structure to prevent leakage. In order to facilitate those skilled in the art to understand the structure of the barrier layer 14, Figure 5 shows a cross-sectional view of a metal stack structure according to some other embodiments of the present application, Figure 8 The cross-sectional views of the metal stacked structures of other embodiments of the present application are shown as follows: Figure 5 and Figure 8 As shown, the metal stack structure further includes: a barrier layer 14, the barrier layer 14 covers the surface of the first metal layer 11 and the junction between the first metal layer 11 and the second metal layer 12. As an example, the material of the barrier layer 14 can be aluminum oxide Al 2 O 3 .

[0050] It should be noted that Figure 5 The cutting direction in Figure 4 The cutting direction is consistent with that in Figure 8 The cutting direction in Figure 7 The cutting direction is the same as in the above examples. The difference is that Figure 5 and Figure 8 The metal stack structure shown includes a barrier layer 14, Figure 4 and Figure 7 The metal stack structure shown does not include the barrier layer 14. In other words, Figure 5 The metal stack structure shown in Figure 4A barrier layer 14 is added to the metal stack structure shown. Figure 8 The metal stack structure shown in Figure 7 A barrier layer 14 is additionally provided on the basis of the metal stack structure shown.

[0051] The above embodiments introduce a planar metal stacked structure. The preparation method of the metal stacked structure is described below.

[0052] Fig. 9 An exemplary flow chart of a method 900 for preparing a metal stacked structure according to some embodiments of the present application is shown. Fig. 9 As shown, the method includes: In step S901, a first metal layer having a first structure is prepared; In step S902, a second metal layer is deposited on the first metal layer; In step S903, a photoresist is coated on the second metal layer; In step S904, developing and curing the photoresist in the target area; In step S905 , a second metal layer having a second structure is formed by etching using a photolithography process, so that the first metal layer and the second metal layer form a planar metal stacked structure.

[0053] According to the previous Figure 3-Figure 8 It can be seen from the contents of the described embodiments that the first metal layer can be a metal layer with a groove structure or a metal layer with an extended structure.

[0054] When the first structure is a groove structure, the target area in step S904 includes an area embedded in the groove structure and an area extending along the opening direction of the groove structure, and the second structure in step S905 includes an extended structure embedded in the groove structure. As an example, the structure of the first metal layer having the first structure and the second metal layer having the second structure can be referred to in conjunction with the above Figure 3 and Figure 4 Described embodiments.

[0055] When the first structure is an extended structure, the target area in step S904 includes a groove-shaped area that semi-surrounds the extended structure, and the second structure in step S905 includes a groove structure embedded in the extended structure. As an example, the structure of the first metal layer having the first structure and the second metal layer having the second structure can be referred to in conjunction with the above. Figure 6 and Figure 7 Described embodiments.

[0056] Furthermore, in some embodiments, Figure 5 or Figure 8As shown, a barrier layer needs to be set between the first metal layer and the second metal layer to prevent leakage. Therefore, between step S901 and step S902, a step of depositing a barrier layer on the first metal layer can also be performed to cover the exposed surface of the first metal layer with the barrier layer. At this time, step S902 needs to deposit a second metal layer on the barrier layer and the exposed substrate.

[0057] In the above embodiment, the second metal layer with the second structure is prepared by photolithography, and the metal surface is precisely processed by steps such as illumination, development and etching. The first metal layer with the first structure can also be prepared by photolithography.

[0058] Fig.10 FIG. 1 shows an exemplary flow chart of a method 1000 for preparing a first metal layer in some embodiments of the present application. It can be understood that the method for preparing the first metal layer is a specific implementation of the aforementioned step S901. Fig. 9 The features described can be applied here analogously. Fig.10 As shown, the method includes: In step S1001, a first metal layer is deposited on a substrate; In step S1002, a photoresist is coated on the first metal layer; In step S1003, developing and curing the photoresist in the preset area; In step S1004, a first metal layer having a first structure is formed by etching using a photolithography process.

[0059] According to the previous Figure 3-Figure 8 It can be seen from the contents of the described embodiments that the first metal layer can be a metal layer with a groove structure or a metal layer with an extended structure.

[0060] When the first structure is a groove structure, the preset area includes a linear area and at least two protruding areas, the linear area and the protruding area are connected to form a groove shape, the linear area is the groove bottom, the protruding area is the groove wall, and the first metal layer includes a linear conductive portion located in the linear area and a protruding conductive portion located in the protruding area. At this time, when the second metal layer is subjected to a photolithography process, the target area includes a strip area and an interlocking area extending from the strip area, the interlocking area is interlocked in the preset area, and the second metal layer includes a strip conductive portion located in the strip area and an interlocking conductive portion located in the interlocking area. As an example, the structure of the first metal layer having the first structure and the second metal layer having the second structure can be referred to in conjunction with the foregoing text. Figure 3 and Figure 4 Described embodiments.

[0061] When the first structure is an extended structure, the preset area includes a strip area, and the first metal layer includes a strip conductive portion located in the strip area. At this time, when the second metal layer is subjected to a photolithography process, the target area includes a linear area and at least two protruding areas, the linear area and the protruding area are connected and are in the shape of a groove that semi-surrounds the preset area, the linear area is the groove bottom, the protruding area is the groove wall, and the second metal layer includes a linear conductive portion located in the linear area and a protruding conductive portion located in the protruding area. As an example, the structure of the first metal layer having the first structure and the second metal layer having the second structure can be referred to in conjunction with the foregoing text. Figure 6 and Figure 7 Described embodiments.

[0062] In order to facilitate the understanding of those skilled in the art, Fig.11 and Fig.12 The preparation processes of the two metal stacked structures shown in the above embodiments are described in detail. Fig.11 A schematic diagram showing a preparation process of a metal stacked structure according to some embodiments of the present application is shown. Fig.12 Schematic diagrams showing the preparation process of the metal stacked structure according to other embodiments of the present application.

[0063] See first Fig.11 In step a, an oxide layer is deposited and grown on the silicon substrate to complete the preparation of the zero mark layer. In practical applications, the material of the oxide layer can be SiO 2 .

[0064] In step b, a first metal layer, a dielectric anti-reflective coating (DARC) and a photoresist layer of a certain thickness are deposited and grown on the oxide layer, wherein the dielectric anti-reflective coating is a material layer used to reduce light reflection during photolithography in semiconductor manufacturing. The material may be silicon oxynitride or other nitrogen-containing compounds. The main function is to reduce light reflection during photolithography, thereby reducing a series of process problems caused by light reflection, such as standing wave effect, reduced exposure latitude, impaired uniformity of key dimensions, and blurred pattern edges. The dielectric anti-reflective coating can also prevent the acid catalyst in the photoresist from neutralizing with the nitrogen-containing amino group in the dielectric anti-reflective coating, thereby avoiding photoresist poisoning, thereby reducing the deformation of the photoresist pattern or the residue of the photoresist. In step b, the photoresist layer in the preset area needs to be developed and cured, wherein the preset area includes a linear area and at least two protruding areas, the linear area and the protruding area are connected to form a groove shape, the linear area is the groove bottom, and the protruding area is the groove wall. The developed photoresist layer is caliper-shaped or U-shaped from a top-down perspective.

[0065] In step c, etching of the first metal layer is performed and the etching stops on the oxide layer, the solidified photoresist is cleaned off and wet cleaning is performed, and the obtained first metal layer is caliper-shaped or U-shaped when viewed from a top view. Specifically, the first metal layer includes: a linear conductive portion and at least two protruding conductive portions, the protruding conductive portion is connected to the linear conductive portion to form a groove structure, the protruding conductive portion is the groove wall of the groove structure, and the linear conductive portion is the groove bottom of the groove structure. Furthermore, the protruding conductive portion is a conductive portion extending along the length direction of the linear conductive portion, and the protruding conductive portion is perpendicular to the linear conductive portion.

[0066] In step d, a barrier layer is formed on the first metal layer having the first structure, and the material of the barrier layer may be aluminum oxide. From a top view, the barrier layer is also caliper-shaped or U-shaped.

[0067] In step e, a second metal layer is deposited. At this time, the second metal layer covers the exposed oxide layer and the barrier layer.

[0068] In step f, a photoresist is applied to form a photoresist layer, and the photoresist in the target area is cured by development. Fig.11 As shown in the pink area of ​​step f, from a top view, the target area includes a strip area and an embedded area extending from the strip area, and the embedded area is embedded in the preset area, that is, the embedded area is embedded in the groove structure of the first metal layer.

[0069] In step g, the second metal layer is etched and the etching stops on the oxide layer, the solidified photoresist is washed off and wet cleaning is performed, and a planar metal stacked structure can be obtained. In the metal stacked structure, the second metal layer has a second structure, and the second structure is an extended structure. Specifically, the second metal layer with the second structure includes: a strip-shaped conductive part and an embedded conductive part extending from one side of the strip-shaped conductive part, wherein the embedded conductive part is embedded in the groove structure of the first metal layer and connected to the linear conductive part in the first metal layer.

[0070] See below Fig.12 ,right Figure 6 and Figure 7 The preparation process of the metal stack structure described is described. Fig.12 As shown, in step a, an oxide layer is deposited and grown on the silicon substrate to complete the preparation of the zero mark layer. In practical applications, the material of the oxide layer can be SiO 2 .

[0071] In step b, a first metal layer, a dielectric anti-reflective coating (DARC) and a photoresist layer of a certain thickness are deposited and grown on the oxide layer, wherein the dielectric anti-reflective coating is a material layer used to reduce light reflection during photolithography in semiconductor manufacturing, and its material can be silicon oxynitride or other nitrogen-containing compounds. Its main function is to reduce light reflection during photolithography, thereby reducing a series of process problems caused by light reflection, such as standing wave effect, reduced exposure latitude, impaired uniformity of key dimensions, and blurred pattern edges. The dielectric anti-reflective coating can also prevent the acid catalyst in the photoresist from neutralizing with the nitrogen-containing amino group in the dielectric anti-reflective coating, thereby avoiding photoresist poisoning, and further reducing the deformation of the photoresist pattern or the residue of the photoresist. In step b, the photoresist layer in the preset area needs to be developed and cured, wherein the preset area includes a strip-shaped area, and the developed photoresist layer is in a straight line from a top view.

[0072] In step c, the first metal layer is etched and the etching stops on the oxide layer, the solidified photoresist is cleaned and wet cleaning is performed, and the obtained first metal layer is in a straight line shape from a top view. Specifically, the first metal layer includes: a strip-shaped conductive portion.

[0073] In step d, a barrier layer is formed on the first metal layer having the first structure, and the material of the barrier layer may be aluminum oxide. From a top view, the barrier layer is also in a straight line shape.

[0074] In step f, a photoresist is applied to form a photoresist layer, and the photoresist in the target area is cured by development. Fig.12 As shown in the pink area of ​​step f, from a top-down perspective, the target area includes a linear area and at least two protruding areas, the linear area and the protruding area are connected and form a groove shape that semi-surrounds the preset area, the linear area is the groove bottom, and the protruding area is the groove wall. From a top-down perspective, the target area is F-shaped.

[0075] In step g, the second metal layer is etched and the etching stops on the oxide layer, the solidified photoresist is cleaned and wet cleaning is performed to obtain a planar metal stacked structure. In the metal stacked structure, the second metal layer has a second structure, and the second structure is a groove structure. Specifically, the second metal layer with the second structure includes: a linear conductive part and at least two protruding conductive parts, wherein the protruding conductive part is connected to the linear conductive part to form a groove structure, the protruding conductive part is the groove wall of the groove structure, and the linear conductive part is the groove bottom of the groove structure.

[0076] Furthermore, in combination with the above Fig.11 or Fig.12In the described embodiments, the first metal layer and the second metal layer can be cut flush at the intersection of the two layers, thereby forming a planar metal stacked structure with uniform overall height. Alternatively, in step f, the target area to be developed and cured can be expanded outward to a certain extent so that it covers a portion of the first metal layer, thereby reserving a certain buffer space for etching the second metal layer. Specifically, in some embodiments, the target area can also include: an area located at the bottom of the groove structure and covering a portion of the top surface of the first metal layer.

[0077] By adjusting the target area, the top surface of the second metal layer can have an epitaxial surface compared to its bottom surface, and the epitaxial surface is located at the bottom of the groove structure and covers part of the first metal layer. Fig.11 When the metal stacked structure is prepared by the process shown, at the position where the first metal layer and the second metal layer meet, there will be an epitaxial surface on the top of the embedded conductive part in the second metal layer, which at least covers part of the top surface of the linear conductive part of the first metal layer, and can also cover part of the top surface of the protruding conductive part of the first metal layer. Fig.12 When the metal stack structure is prepared in the process shown, at the position where the first metal layer and the second metal layer are connected, an epitaxial surface will exist on the top of the linear conductive part and / or the protruding conductive part in the second metal layer, which covers part of the top surface of the strip conductive part of the first metal layer. This epitaxial surface design can make the area and electrical performance of the planar metal stack structure better, and better meet the use requirements.

[0078] Through the previous combination Figure 9-12 The various methods described can improve the process difficulty of the existing metal stack structure, make the process capability more stable, and shorten the time to mass production.

[0079] In addition, the thickness of the second metal layer prepared by the existing process needs to be at least 1.5 times thicker than the thickness of the first metal layer in order to improve the step height effect brought by the first metal layer. By preparing a planar metal stack structure using the above method, this requirement can be reduced. The second metal layer only needs to be 1.2 times thicker than the first metal layer, thereby further optimizing the metal stack structure.

[0080] Although multiple embodiments of the present application have been shown and described herein, it is obvious to those skilled in the art that such embodiments are provided only by way of example. Those skilled in the art can think of many changes, modifications and alternatives without departing from the thought and spirit of the present application. It should be understood that in the process of practicing the present application, various alternatives to the embodiments of the present application described herein can be adopted. The attached claims are intended to limit the scope of protection of the present application, and therefore cover equivalents or alternatives within the scope of these claims.

Claims

1. A metal laminate structure, characterized in that: include: at least two metal layers, the bottom surfaces of the two metal layers being located on the same substrate; One of the metal layers has a groove structure, and the other metal layer has an extension structure, wherein the extension structure is embedded in the groove structure to form a planar metal stacked structure.

2. The metal laminate structure according to claim 1, characterized in that: The at least two metal layers include: a first metal layer (11) and a second metal layer (12); The first metal layer (11) comprises: a linear conductive portion (101) and at least two externally protruding conductive portions (102), the externally protruding conductive portions (102) being connected to the linear conductive portion (101) to form a groove structure, the externally protruding conductive portions (102) being groove walls of the groove structure, and the linear conductive portions (101) being groove bottoms of the groove structure; The second metal layer (12) comprises: a strip-shaped conductive portion (103) and an embedded conductive portion (104) extending from one side of the strip-shaped conductive portion (103), wherein the embedded conductive portion (104) is embedded in the groove structure and connected to the linear conductive portion (101).

3. The metal laminate structure according to claim 1, characterized in that: The at least two metal layers include: a first metal layer (11) and a second metal layer (12); The second metal layer (12) comprises: a linear conductive portion (101) and at least two externally protruding conductive portions (102), wherein the externally protruding conductive portions (102) are connected to the linear conductive portion (101) to form a groove structure, the externally protruding conductive portions (102) are groove walls of the groove structure, and the linear conductive portions (101) are groove bottoms of the groove structure; The first metal layer (11) comprises: a strip-shaped conductive portion (103), and a portion of the strip-shaped conductive portion (103) is embedded in the groove structure.

4. The metal laminate structure according to claim 2, characterized in that: In the first metal layer (11), the protruding conductive portion (102) is a conductive portion extending along the length direction of the linear conductive portion (101), and the protruding conductive portion (102) is perpendicular to the linear conductive portion (101) to form a caliper-shaped or U-shaped groove structure; In the second metal layer (12), the embedded conductive portion (104) is perpendicular to the strip-shaped conductive portion (103).

5. The metal laminate structure according to claim 3, characterized in that: The outwardly protruding conductive portion (102) is a conductive portion extending toward the same side of the linear conductive portion (101), and the outwardly protruding conductive portion (102) is perpendicular to the linear conductive portion (101) to form an F-shaped groove structure.

6. The metal laminate structure according to any one of claims 2 to 5, characterized in that: The top surface of the second metal layer (12) has an epitaxial surface compared to its bottom surface, the epitaxial surface is located at the bottom of the groove structure and covers part of the first metal layer (11).

7. The metal laminate structure according to any one of claims 2 to 5, characterized in that: Also includes: Barrier layer (14); The barrier layer (14) covers the surface of the first metal layer (11) and the junction between the first metal layer (11) and the second metal layer (12), so as to function as an intermediate dielectric layer of the metal stacked structure.

8. A method for preparing a metal laminate structure, characterized in that: include: preparing a first metal layer having a first structure; depositing a second metal layer on the first metal layer; coating a photoresist on the second metal layer; Developing and curing the photoresist in the target area; as well as Etching to form a second metal layer having a second structure by using a photolithography process, so that the first metal layer and the second metal layer form a planar metal stacked structure; Wherein, when the first structure is a groove structure, the target area includes an area embedded in the groove structure and extending along the opening direction of the groove structure, and the second structure includes an extended structure embedded in the groove structure; When the first structure is an extension structure, the target area includes a groove-shaped area semi-surrounding the extension structure, and the second structure includes a groove structure embedded in the extension structure.

9. The method for preparing a metal laminate structure according to claim 8, characterized in that: The preparation of the first metal layer having the first structure comprises: depositing a first metal layer on a substrate; coating a photoresist over the first metal layer; Developing and curing the photoresist in a predetermined area; and Etching to form a first metal layer having a first structure by using a photolithography process; Wherein, when the first structure is a groove structure, the preset area includes a linear area and at least two protruding areas, the linear area and the protruding areas are connected to form a groove shape, the linear area is the groove bottom, the protruding area is the groove wall, the first metal layer includes a linear conductive part located in the linear area and a protruding conductive part located in the protruding area, the target area includes a strip area and an embedded area extending from the strip area, the embedded area is embedded in the preset area, and the second metal layer includes a strip conductive part located in the strip area and an embedded conductive part located in the embedded area; When the first structure is an extended structure, the preset area includes a strip-shaped area, the first metal layer includes a strip-shaped conductive portion located in the strip-shaped area, the target area includes a linear area and at least two protruding areas, the linear area and the protruding area are connected and are in the shape of a groove that semi-surrounds the preset area, the linear area is the groove bottom, the protruding area is the groove wall, and the second metal layer includes a linear conductive portion located in the linear area and a protruding conductive portion located in the protruding area.

10. The method for preparing a metal laminate structure according to claim 8, characterized in that: The target area also includes: an area located at the bottom of the groove structure and covering a portion of the top surface of the first metal layer.

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