Hybrid bonding structure and method of making the same

Abstract

A hybrid junction structure and a method of fabricating the same are disclosed. The hybrid junction structure includes a first conductive structure and a second conductive structure. The first conductive structure includes a first conductive layer, a first buffer layer surrounding and contacting the first conductive layer, a first air gap surrounding and contacting the first buffer layer, and a first dielectric layer surrounding and contacting the first air gap. The second conductive structure includes a second conductive layer, a second buffer layer contacting the second conductive layer, and a second dielectric layer surrounding the second buffer layer. The second conductive layer is joined with the first conductive layer, and the first dielectric layer is joined with the second dielectric layer.

Description

Technical Field

[0001] This invention relates to a hybrid bonding structure and its fabrication method, and more particularly to a hybrid bonding structure and its fabrication method that prevents metal atoms from diffusing into the interlayer dielectric layer when wafer alignment is misaligned. Background Technology

[0002] In recent years, the integration density of various electronic components has been continuously increasing. On the one hand, this increase in integration density comes from the continuous reduction of the minimum feature size, allowing more smaller components to be integrated into a given area. In addition, stacking and bonding multilayer wafers to form three-dimensional integrated circuits is another method to increase component integration. Wafer bonding can be achieved by adhering two wafers together through the bonding of two dielectric materials, or through the bonding of two metal materials, or by combining the aforementioned two bonding mechanisms.

[0003] However, there are still many challenges to be addressed for 3D integrated circuit technology. For example, when bonding two wafers, misalignment can cause metal materials to come into contact with the interlayer dielectric layer and metal atoms to diffuse into the interlayer dielectric layer, causing contamination. Summary of the Invention

[0004] In view of this, the present invention provides a hybrid bonding structure and its fabrication method to solve the problem of metal atoms diffusing into the interlayer dielectric layer when wafer alignment is off.

[0005] According to a preferred embodiment of the present invention, a hybrid bonding structure includes a first conductive structure and a second conductive structure. The first conductive structure includes a first conductive layer, a first buffer layer surrounding and contacting the first conductive layer, a first air gap surrounding and contacting the first buffer layer, and a first dielectric layer surrounding and contacting the first air gap. The second conductive structure includes a second conductive layer, a second buffer layer contacting the second conductive layer, and a second dielectric layer surrounding the second buffer layer. The second conductive layer and the first conductive layer are bonded, and the first dielectric layer and the second dielectric layer are bonded.

[0006] According to another preferred embodiment of the present invention, a method for fabricating a hybrid bonding structure includes performing an air gap fabrication process, comprising providing a first dielectric layer, then forming an etch stop layer covering the first dielectric layer, forming a second dielectric layer covering the etch stop layer, forming a trench located in the second dielectric layer and the etch stop layer, then sequentially forming a first buffer layer and a first conductive layer to fill the trench, then forming a patterned mask covering the second dielectric layer, wherein the first buffer layer, the first conductive layer and the second dielectric layer located around the first buffer layer are exposed by the patterned mask, followed by an etching process to remove the second dielectric layer exposed by the patterned mask to form an air gap around the first buffer layer, and finally removing the patterned mask to complete an Nth conductive structure, wherein N is a positive integer from 1 to 2.

[0007] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. However, the following preferred embodiments and drawings are for reference and illustration only and are not intended to limit the present invention. Attached Figure Description

[0008] Figures 1 to 5A This is a schematic diagram illustrating an air gap manufacturing process according to a first preferred embodiment of the present invention;

[0009] Figure 5B This is a schematic diagram of a variation of an air gap manufacturing process according to a first preferred embodiment of the present invention;

[0010] Figure 5C This is a schematic diagram of another variation of an air gap manufacturing process according to the first preferred embodiment of the present invention;

[0011] Figure 6 for Figure 5A , Figure 5B and Figure 5C Top view;

[0012] Figures 7 to 10 A schematic diagram illustrating an air gap manufacturing process according to a second preferred embodiment of the present invention;

[0013] Figure 11A , Figure 11B , Figure 11C , Figure 11D , Figure 11E , Figure 11F and Figure 11G This is a schematic diagram illustrating a hybrid joint structure according to several preferred embodiments of the present invention.

[0014] Explanation of main component symbols

[0015] 10: First dielectric layer

[0016] 12: Metal layer

[0017] 14: Etching Stop Layer

[0018] 16: Second dielectric layer

[0019] 18: Trench

[0020] 20: First Buffer Layer

[0021] 22: First conductive layer

[0022] 24: Patterned Mask

[0023] 26: Air gap

[0024] 28a: First conductive structure

[0025] 28b: Second conductive structure

[0026] 28c: Third conductive structure

[0027] 30: Sacrifice Layer

[0028] 32: Spacer wall

[0029] 34: Groove

[0030] 100: Hybrid Joint Structure

[0031] 110: Fourth dielectric layer

[0032] 112: Metal layer

[0033] 114: Etching Stop Layer

[0034] 116: Third dielectric layer

[0035] 120: Second Buffer Layer

[0036] 122: Second conductive layer

[0037] 200: Hybrid Joint Structure

[0038] 300: Hybrid Joint Structure

[0039] 400: Hybrid Joint Structure

[0040] 500: Hybrid Joint Structure

[0041] 600: Hybrid Joint Structure

[0042] 700: Hybrid Joint Structure

[0043] W: Width Detailed Implementation

[0044] Figures 1 to 5A This is a process for manufacturing an air gap according to a first preferred embodiment of the present invention. Figure 5B This is a variation of the air gap manufacturing process of the first preferred embodiment of the present invention. Figure 5C This is another variation of the air gap manufacturing process according to the first preferred embodiment of the present invention. For example... Figure 1 As shown, a first dielectric layer 10 is provided. The first dielectric layer 10 can be disposed on a substrate (not shown). The substrate can contain several interlayer dielectric layers, and metal interconnects have been formed in the interlayer dielectric layers. The substrate can be a silicon substrate, germanium substrate, gallium arsenide substrate, silicon-germanium substrate, indium phosphide substrate, gallium nitride substrate, silicon carbide substrate, or silicon-coated insulating substrate. In addition, the substrate can be an uncut wafer, a circuit board, an interposer, or a die that has been cut and is to be packaged. Furthermore, a metal layer 12, such as a metal plug, is disposed in the first dielectric layer 10. Then, an etch stop layer 14 is formed to cover the first dielectric layer 10. The etch stop layer 14 contains SiC or SiCN, and the thickness of the etch stop layer 14 is preferably between 1 nm and 500 nm. A second dielectric layer 16 is then formed to cover the etch stop layer 14. The second dielectric layer 16 and the etch stop layer 14 are then etched to form a trench 18 located in the second dielectric layer 16 and the etch stop layer 14. At this time, the metal layer 12 is exposed by the trench 18.

[0045] like Figure 2 As shown, a first buffer layer 20 and a first conductive layer 22 are sequentially formed to fill the trench 18. The first buffer layer 20 compliantly covers the second dielectric layer 16 and the trench 18, and the first conductive layer 22 covers the first buffer layer 20. The first buffer layer 20 contains TiN, TaN, or Ti / TiN, but is not limited to these. Other conductive layers that can block metal diffusion can also be used. In this embodiment, the thickness of the first buffer layer 20 is preferably between 1 nm and 100 nm, and the first buffer layer 20 is preferably formed by deposition. The first conductive layer 22 contains Cu, Al, W, Ti, TiN, Ta, Cu / Al, TaN, or a combination of the above materials. In this embodiment, the thickness of the first conductive layer 22 is preferably between 1 nm and 5000 nm. In this embodiment, the first conductive layer 22 is preferably Cu and is formed by electroplating.

[0046] like Figure 3 As shown, a chemical mechanical polishing process is performed to remove the first conductive layer 22 and the first buffer layer 20 outside the trench 18. Figure 4As shown, a patterned mask 24 is formed to cover the second dielectric layer 16 to define the location of the subsequent air gap, wherein the first buffer layer 20, the first conductive layer 22 and the second dielectric layer 16 located around the first buffer layer 20 are exposed by the patterned mask 24, which is preferably a photoresist.

[0047] Please see Figure 5A , Figure 5B , Figure 5C and Figure 6 ,in Figure 6 for Figure 5A , Figure 5B and Figure 5C The top view shows the process. First, an etching process is performed using a patterned mask 24 as a mask to remove the second dielectric layer 16 exposed by the patterned mask 24, forming an air gap 26 surrounding the first buffer layer 20. After the air gap 26 is completed, the patterned mask 24 is removed. The aforementioned etching process includes dry etching, partial dry etching, or wet etching, which can be selected arbitrarily depending on product requirements. Figure 5A The illustration shows an etching process using a dry etching method, specifically a dry etching process that removes the second dielectric layer 16 until the etch stop layer 14 is exposed. Figure 5B The illustration depicts an etching process using a partial dry etching method, such as... Figure 5B As shown, only a portion of the thickness of the second dielectric layer 16 was removed and the etch stop layer 14 was not exposed. Figure 5C The illustration depicts an etching process using a wet etching method, such as... Figure 5C As shown, after wet etching removes the second dielectric layer 16, an arc-shaped profile is formed on the surface of the second dielectric layer 16. Figure 5C The wet etching stops before reaching the etch stop layer 14; however, depending on the requirements, it can be continued until the etch stop layer 14 is exposed. The etchant in dry etching, partial dry etching, or wet etching only removes the second dielectric layer 16. After completing the air gap 26 and removing the patterned mask 24, the air gap fabrication process of the present invention is complete, and a first conductive structure 28a is finished. Another substrate can then be provided, and the air gap fabrication process of the first preferred embodiment can be repeated to form a second conductive structure. The second conductive structure can be fabricated using dry etching, partial dry etching, or a wet etching, so the second conductive structure can be... Figure 5A , Figure 5B or Figure 5C One of them. Similarly, the second conductive structure can be on an uncut wafer, a circuit board, an interposer, or a die that has been cut and is ready for packaging.

[0048] Figures 7 to 10 The present invention provides a second preferred embodiment of an air gap manufacturing process, wherein components having the same function and position will use the component designations in the first preferred embodiment. For related descriptions, please refer to the first preferred embodiment, which will not be repeated here.

[0049] like Figure 7 As shown, a first dielectric layer 10 is provided, in which a metal layer 12 is disposed. Then an etch stop layer 14 is formed to cover the first dielectric layer 10, and then a sacrificial layer 30 is formed to cover part of the etch stop layer 14. The sacrificial layer 30 and the metal layer 12 at least partially overlap. The sacrificial layer 30 is preferably a silicon-containing material, such as polysilicon.

[0050] like Figure 8 As shown, a spacer wall 32 is formed around the sacrificial layer 30, followed by the formation of a second dielectric layer 16 covering the etch stop layer 14. The upper surface of the second dielectric layer 16 is flush with the upper surface of the sacrificial layer 30. The spacer wall 32 will later become an air gap, so the size of the air gap can be controlled by the thickness of the spacer wall 32. Figure 9 As shown, the sacrificial layer 30 and the etch stop layer 14 directly below the sacrificial layer 30 are removed to form a trench 18. Then, a first buffer layer 20 and a first conductive layer 22 are sequentially formed to fill the trench 18, and the first buffer layer 20 and the first conductive layer 22 outside the trench 18 are removed. Figure 10 as well as Figure 6 As shown, the gap wall 32 is removed to form an air gap 26 surrounding the first buffer layer 20. This completes the air gap fabrication process of the present invention and a first conductive structure 28a is now complete. The air gap fabrication process of the second preferred embodiment can then be repeated on another substrate to form a second conductive structure.

[0051] Figure 11A The method for manufacturing a hybrid joint structure illustrated in the preferred embodiment of the present invention uses the component designations in the first preferred embodiment for reference illustrative purposes. For related descriptions, please refer to the first preferred embodiment, which will not be repeated here.

[0052] like Figure 11AAs shown, after fabricating a first conductive structure 28a and a second conductive structure 28b using the air gap fabrication process of the first preferred embodiment, the first conductive layer 22 in the first conductive structure 28a and the first conductive layer 22 in the second conductive structure 28b are aligned and bonded. Similarly, the second dielectric layer 16 in the first conductive structure 22 and the second dielectric layer 16 in the second conductive structure 28b are aligned and bonded. For example, if the first conductive structure 28a is on an uncut wafer and the second conductive structure 28b is on another uncut wafer, the alignment and bonding is a wafer-to-wafer bonding. However, this is not limited to this; the bonding of the first conductive structure 28a and the second conductive structure 28b can also be a die-to-die bonding, a wafer-to-intermediate bonding, etc. Thus, the hybrid bonding structure 100 of the present invention is completed. In this embodiment, the air gap 26 in the first conductive structure 28a and the second conductive structure 28b is formed using dry etching.

[0053] In the hybrid bonding structure of the present invention, two conductive structures can be fabricated and bonded using the manufacturing method of the first preferred embodiment or the manufacturing method of the second preferred embodiment, or it can be bonded to another conductive structure that has a conductive layer but no air gap. It is sufficient that at least one of the two bonded conductive structures in the hybrid bonding structure has an air gap. Therefore, besides... Figure 11A The method for manufacturing the hybrid joint structure 100 shown in the example includes various other hybrid joint structures, which will be discussed below. Figure 11B , Figure 11C , Figure 11D , Figure 11E , Figure 11F , Figure 11G The invention will disclose several variations, but apart from the variations described below, any structure that conforms to having an air gap surrounding a buffer layer in one of the two joined conductive structures falls within the scope of this invention. Similarly, Figure 11B , Figure 11C , Figure 11D , Figure 11E , Figure 11F , Figure 11G Alignment bonding can be wafer-to-wafer, die-to-die, wafer-to-intermediate, etc.

[0054] like Figure 11B As shown, after partially dry etching to fabricate the first conductive structure 28a and the second conductive structure 28b using the air gap fabrication process of the first preferred embodiment, the first conductive layer 22 in the first conductive structure 28a and the first conductive layer 22 in the second conductive structure 28b are aligned and bonded, and the second dielectric layer 16 in the first conductive structure 28a and the second dielectric layer 16 in the second conductive structure 28b are aligned and bonded to complete the hybrid bonding structure 200.

[0055] like Figure 11C As shown, after the first conductive structure 28a and the second conductive structure 28b are fabricated by wet etching using the air gap fabrication process of the first preferred embodiment, the first conductive layer 22 in the first conductive structure 22a and the first conductive layer 22 in the second conductive structure 28b are aligned and bonded, and the second dielectric layer 16 in the first conductive structure 28a and the second dielectric layer 16 in the second conductive structure 28b are aligned and bonded to complete the hybrid bonding structure 300.

[0056] like Figure 11D As shown, a first conductive structure 28a is fabricated using the air gap fabrication process of the first preferred embodiment, and a third conductive structure 28c is also provided. The third conductive structure 28c includes a second conductive layer 122, a second buffer layer 120 contacting the second conductive layer 122, and a third dielectric layer 116 contacting the second buffer layer 120. In other words, there is no air gap in the third conductive structure 28c. Furthermore, a fourth dielectric layer 110 is disposed below the third dielectric layer 116. A metal layer 112 is disposed in the fourth dielectric layer, overlapping the second conductive layer 122. An etch stop layer 114 is disposed between the fourth dielectric layer 110 and the third dielectric layer 116. Then, the first conductive layer 22 in the first conductive structure 28a and the second conductive layer 122 in the third conductive structure 28c are bonded, and the second dielectric layer 16 in the first conductive structure 28a and the third dielectric layer 116 in the third conductive structure 28c are bonded to complete the hybrid bonding structure 400. Although this variation uses a dry-etched first conductive structure 28a as an example, partial dry etching is employed. Figure 5B ) or wet etching ( Figure 5C The first conductive structure 28a produced by the method is also applicable to this variant.

[0057] like Figure 11E As shown, after fabricating the first conductive structure 28a and the second conductive structure 28b using the air gap fabrication process of the second preferred embodiment, the first conductive layer 22 in the first conductive structure 28a and the first conductive layer 22 in the second conductive structure 28b are aligned and bonded, and the second dielectric layer 16 in the first conductive structure 28a and the second dielectric layer 16 in the second conductive structure 28b are aligned and bonded to complete the hybrid bonding structure 500.

[0058] like Figure 11FAs shown, after fabricating the first conductive structure 28a using the air gap fabrication process of the second preferred embodiment, a third conductive structure 28c without an air gap as described above is further provided. Then, the first conductive layer 22 in the first conductive structure 28a and the second conductive layer 122 in the third conductive structure 28c are aligned and bonded, and the second dielectric layer 16 in the first conductive structure 22a and the third dielectric layer 116 in the third conductive structure 28c are aligned and bonded to complete the hybrid bonding structure 600.

[0059] like Figure 11G As shown, after the first conductive structure 28a is fabricated by dry etching and the second conductive structure 28b is fabricated by wet etching using the air gap fabrication process of the first preferred embodiment, the first conductive layer 22 in the first conductive structure 28a and the first conductive layer 22 in the second conductive structure 28b are joined together, and the second dielectric layer 16 in the first conductive structure 28a and the second dielectric layer 16 in the second conductive structure 28b are joined together to complete the hybrid bonding structure 700. It is worth noting that during the bonding process, an alignment error occurs, so part of the first conductive layer 22 in the first conductive structure 28a is not attached to the first conductive layer 22 in the second conductive structure 28b, but is in contact with the air gap 26. However, the metal atoms of the first conductive layer 22 cannot diffuse through the air gap 26, thus avoiding the problem of contamination caused by the diffusion of metal atoms.

[0060] Figure 11A , Figure 11B , Figure 11C , Figure 11D , Figure 11E , Figure 11F and Figure 11G This is a hybrid joining structure illustrated according to several preferred embodiments of the present invention, wherein elements having the same function and position will use the element reference numerals in the first preferred embodiment, and the relevant descriptions can be found in the first preferred embodiment, which will not be repeated here.

[0061] like Figure 11A As shown, a hybrid bonding structure 100 includes a first conductive structure 28a and a second conductive structure 28b. The first conductive structure 28a and the second conductive structure 28b have the same structural position in the top view, both being... Figure 6 As an example, please also refer to Figure 6 and Figure 11AThe first conductive structure 28a and the second conductive structure 28b are identical, both comprising a first conductive layer 22, a first buffer layer 20 surrounding and contacting the first conductive layer 22, an air gap 26 surrounding and contacting the first buffer layer 20, and a second dielectric layer 16 surrounding and contacting the air gap 26. The upper surface of the second dielectric layer 16 is flush with the upper surface of the first conductive layer 22. The first conductive layer 22 in the first conductive structure 28a contacts and adheres to the first conductive layer 22 in the second conductive structure 28b, and the second dielectric layer 16 in the first conductive structure 28a contacts and adheres to the second dielectric layer 16 in the second conductive structure 28b. The depth of the air gap 26 is equal to the depth of the second dielectric layer 16, and an etch stop layer 14 is exposed through the air gap 26. Furthermore, the width W of the air gap 26 is between 0.01 μm and 10 μm. Furthermore, the air gap 26 forms a groove 34 in the second dielectric layer 16. The bottom of the groove 34 is a horizontal surface, the sidewalls of the groove 34 are vertical sidewalls, and the bottom width of the groove 34 is the same as the opening width of the groove.

[0062] A first dielectric layer 10 is disposed beneath the second dielectric layer 16 in the first conductive structure 28a and the second conductive structure 28b. A metal layer 12, such as a metal plug, is disposed in the first dielectric layer 10. An etch stop layer 14 is disposed between the first dielectric layer 10 and the second dielectric layer 16. The etch stop layer 14 comprises SiC or SiCN, and the thickness of the etch stop layer 14 is preferably between 1 nm and 500 nm.

[0063] The materials of the first dielectric layer 10 and the second dielectric layer 16 each comprise silicon oxide, silicon oxynitride, phosphosilicate glass, borophosphosilicate glass, fluorinated silicate glass, organosilicate glasses, silicon oxycarbide (SiOC), spin-on glass, spin-on polymer, silicon carbide, or a combination of the above materials. The thickness of the second dielectric layer 16 is preferably between 1 nm and 5000 nm. The first buffer layer 20 comprises TiN, TaN, or Ti / TiN. The thickness of the first buffer layer 20 is preferably between 1 nm and 100 nm. The first conductive layer 22 comprises Cu, Al, W, Ti, TiN, Ta, Cu / Al, TaN, or a combination of the above materials. In this embodiment, the thickness of the first conductive layer 22 is preferably between 1 nm and 5000 nm. Furthermore, the air gap 26 may contain air, oxygen, nitrogen, or an inert gas.

[0064] like Figure 11BAs shown, the hybrid bonding structure 200 is joined using a first conductive structure 28a and a second conductive structure 28b. The first conductive structure 28a and the second conductive structure 28b have the same structure, and... Figure 11A The difference between the hybrid bonding structure 100 and the hybrid bonding structure 200 is that the depth of the air gap 26 in the hybrid bonding structure 200 is less than the depth of the second dielectric layer 16. The rest is the same as the hybrid bonding structure 100, and will not be described in detail here.

[0065] like Figure 11C As shown, the hybrid bonding structure 300 is joined using a first conductive structure 28a and a second conductive structure 28b. The first conductive structure 28a and the second conductive structure 28b are identical. The hybrid bonding structure 300 and Figure 11A The difference between the hybrid bonding structure 100 and the hybrid bonding structure 300 is that the air gap 26 in the hybrid bonding structure 300 forms a groove 34 in the second dielectric layer 16, and the bottom of the groove 34 is arc-shaped. The rest is the same as the hybrid bonding structure 100, and will not be described again here.

[0066] like Figure 11D As shown, the hybrid bonding structure 400 is formed by bonding a first conductive structure 28a and a third conductive structure 28c, and Figure 11A The difference between the hybrid bonding structure 100 and the hybrid bonding structure 400 is that there is no air gap in the third conductive structure 28c. Specifically, the third conductive structure 28c includes a second conductive layer 122, a second buffer layer 120 contacting the second conductive layer 122, and a third dielectric layer 116 contacting the second buffer layer 120. In the hybrid bonding structure 400, the second conductive layer 122 is bonded to the first conductive layer 22, and the second dielectric layer 16 is bonded to the third dielectric layer 116. The second conductive layer 122 comprises Cu, Al, W, Ti, TiN, Ta, Cu / Al, TaN, or a combination of the above materials, and the thickness of the second conductive layer 122 is preferably between 1 nm and 5000 nm. The second buffer layer 120 comprises TiN, TaN, or Ti / TiN. The thickness of the second buffer layer 120 is preferably between 1 nm and 100 nm. The third dielectric layer 116 and the second dielectric layer 16 can be selected from the same material category. The rest of the parts are the same as the hybrid joint structure 100, and will not be described in detail here.

[0067] like Figure 11E As shown, the hybrid bonding structure 500 is joined using a first conductive structure 28a and a second conductive structure 28b. The first conductive structure 28a and the second conductive structure 28b have the same structure. The hybrid bonding structure 500 and Figure 11AThe difference between the hybrid bonding structure 100 and the hybrid bonding structure 500 is that the air gap 26 in the hybrid bonding structure 500 forms a groove 34 in the second dielectric layer 16. The sidewalls of the groove 34 are arc-shaped, and the bottom width of the groove 34 is larger than the opening width of the groove 34. The rest is the same as the hybrid bonding structure 100, and will not be described again here.

[0068] like Figure 11F As shown, the hybrid bonding structure 600 is formed by bonding a first conductive structure 28a and a third conductive structure 28c, and Figure 11E The difference between the hybrid bonding structure 500 and the hybrid bonding structure 600 is that there is no air gap in the third conductive structure 28c. The structure of the third conductive structure 28c is similar to... Figure 11D Similar to the above, please refer to the previous text. In the hybrid bonding structure 600, the second conductive layer 122 of the third conductive structure 28c is bonded to the first conductive layer 22 of the first conductive structure 28a, and the second dielectric layer 16 of the first conductive structure 28a is bonded to the third dielectric layer 116 of the third conductive structure 28c. The rest is the same as the hybrid bonding structure 500, and will not be described again here.

[0069] like Figure 11G As shown, the hybrid bonding structure 700 is formed by bonding the first conductive structure 28a and the second conductive structure 28b. The difference between the hybrid bonding structure 700 and the hybrid bonding structure 100 is that the air gap 26 between the first conductive structure 28a and the second conductive structure 28b in the hybrid bonding structure 700 has a different shape and there is an alignment error between the first conductive structure 28a and the second conductive structure 28b. Therefore, the first conductive layer 22 of the first conductive structure 28a will overlap and contact the air gap 26 of the second conductive structure 28b.

[0070] This invention utilizes an air gap around the buffer layer away from the conductive layer. This avoids diffusion contamination caused by alignment errors when the conductive layer contacts the interlayer dielectric layer during hybrid bonding. Furthermore, since the dielectric constant of the air gap is approximately 1, replacing part of the dielectric layer with the air gap reduces parasitic capacitance between components. Moreover, compared to structures where the air gap is placed between the conductive layer and the buffer layer, this invention places the air gap on the side of the buffer layer away from the conductive layer. This avoids occupying space in the conductive layer and allows the hybrid bonding structure to maintain a lower resistance.

[0071] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made in accordance with the claims of the present invention should be included within the scope of the present invention.

Claims

1. A method for manufacturing a hybrid joint structure, comprising: An air gap fabrication process is performed to complete the Nth conductive structure, where N is a positive integer from 1 to 2. This air gap fabrication process includes: Provide the first dielectric layer; An etch stop layer is formed to cover the first dielectric layer; A sacrificial layer is formed to cover a portion of the etch stop layer, wherein the sacrificial layer is polysilicon; Forming spacer walls around the sacrificial layer; A second dielectric layer is formed to cover the etch stop layer, wherein the upper surface of the second dielectric layer is flush with the upper surface of the sacrificial layer; Remove the sacrificial layer and the etch stop layer directly beneath it to form a trench; A first buffer layer and a first conductive layer are sequentially formed and filled into the trench, with the first buffer layer contacting the gap wall; as well as Remove the gap wall to create an air gap around the buffer layer.

2. The method for manufacturing the hybrid joint structure as described in claim 1, further comprising: Repeat the air gap fabrication process to complete the first conductive structure and the second conductive structure; and The first conductive layer in the first conductive structure and the first conductive layer in the second conductive structure are joined together, and the second dielectric layer in the first conductive structure and the second dielectric layer in the second conductive structure are joined together.

3. The method for manufacturing the hybrid joint structure as described in claim 1, further comprising: A third conductive structure is provided, comprising: Second conductive layer; The second buffer layer surrounds and contacts the second conductive layer; and The third dielectric layer surrounds and contacts the second buffer layer; The first conductive layer in the first conductive structure and the second conductive layer in the third conductive structure are joined together, and the second dielectric layer in the first conductive structure is joined together with the third dielectric layer in the third conductive structure.

4. The method for manufacturing the hybrid joint structure as described in claim 1, wherein the width of the air gap is between 0.01 μm and 10 μm.

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