Hybrid bonding structures and bonding methods

Abstract

This invention provides a hybrid bonding structure and bonding method. The hybrid bonding method includes: providing a first semiconductor structure and a second semiconductor structure to be bonded; the method for forming the first semiconductor structure and / or the second semiconductor structure includes: providing a semiconductor substrate to be bonded; forming a plurality of raised metal connectors on the semiconductor substrate; forming a polymer dielectric layer covering the surface of the semiconductor substrate and exposing the metal connectors; performing a first curing on the polymer dielectric layer, wherein the curing temperature of the first curing is lower than the glass transition temperature of the polymer dielectric layer, and the top surface of the first cured polymer dielectric layer is higher than or equal to the top surface of the metal connectors; performing hot-press bonding to connect the first semiconductor structure and the second semiconductor structure, wherein the hot-press bonding process temperature is higher than the glass transition temperature of the polymer dielectric layer to perform a second curing on the polymer dielectric layer. This invention can optimize the hybrid bonding process.

Description

Technical Field

[0001] This invention relates to the field of integrated circuit manufacturing technology, and in particular to a hybrid bonding structure and bonding method. Background Technology

[0002] As demands for electronic products shift towards miniaturization, multifunctionality, and environmental friendliness, numerous new technologies, materials, and designs have emerged. Improvements in process technology, circuit design, programming algorithms, and manufacturing processes have enabled the scaling down of planar semiconductor devices to smaller dimensions. However, as the feature sizes of semiconductor devices approach their physical limits, planar processes and manufacturing technologies have become challenging and costly. Three-dimensional stacked semiconductor device architectures can address some of the density limitations inherent in planar semiconductor devices.

[0003] Among the various technologies used for stacking semiconductor substrates, hybrid bonding (heterogeneous bonding) has become a key focus of current 3D integration technology research and development because it simultaneously connects circuit leads during the bonding process. For hybrid bonding processes, achieving electrical connections between wafers while completing wafer bonding places extremely high demands on the surface morphology of the wafers to be bonded (height difference and flatness, etc.).

[0004] Taking hybrid bonding with polyimide as the dielectric layer as an example, the preparation process generally includes: forming metal bumps in the bonding area, then forming polyimide in the bonding area and completely curing it above the metal bumps. Next, chemical mechanical polishing (CMP) is performed on the cured polyimide to adjust its surface morphology and the height difference between the polyimide and the metal bumps. In the above process of preparing the hybrid structure, CMP polishing is required. However, according to current industry requirements, the surface roughness of the polyimide after CMP polishing needs to be less than 0.5 nm to facilitate dielectric layer bonding, and there are also very high requirements for the height difference between the polyimide and the metal bumps. Therefore, the above bonding method not only requires CMP equipment but also places extremely high demands on it, which greatly increases the difficulty of the entire preparation process. If the conditions of the above CMP process are not met, it will seriously affect the bonding yield, the performance of the bonded product, and its reliability. Summary of the Invention

[0005] The purpose of this invention is to provide a hybrid bonding structure and bonding method for optimizing the hybrid bonding process.

[0006] To solve the above-mentioned technical problems, the present invention provides a hybrid bonding method, comprising:

[0007] A first semiconductor structure and a second semiconductor structure to be bonded are provided. Both the first semiconductor structure and the second semiconductor structure have a polymer dielectric layer and metal connectors embedded in the polymer dielectric layer on their surfaces. A method for forming the first semiconductor structure and / or the second semiconductor structure includes: providing a semiconductor substrate to be bonded; forming a plurality of protruding metal connectors on the semiconductor substrate; forming a polymer dielectric layer covering the surface of the semiconductor substrate and exposing the metal connectors; and performing a first curing on the polymer dielectric layer, wherein the curing temperature of the first curing is lower than the glass transition temperature of the polymer dielectric layer, and the top surface of the first cured polymer dielectric layer is higher than or equal to the top surface of the metal connectors.

[0008] Hot-press bonding is performed to connect the polymer dielectric layer and metal connector on the surfaces of the first semiconductor structure and the second semiconductor structure, respectively. The hot-press bonding process temperature is higher than the glass transition temperature of the polymer dielectric layer, so that the polymer dielectric layer undergoes a second curing.

[0009] Optionally, prior to bonding, at least one of the polymer dielectric layers on the surfaces of the first semiconductor structure and the second semiconductor structure is cured using the first curing process, and the metal connectors on the surfaces of the first semiconductor structure or the second semiconductor structure that are not cured using the first curing process protrude from the corresponding polymer dielectric layers.

[0010] Optionally, the step of forming a plurality of protruding metal connectors on the semiconductor substrate includes:

[0011] A patterned mask layer is formed on a semiconductor substrate, wherein the patterned mask layer has a plurality of first openings that expose portions of the semiconductor substrate;

[0012] A metal adhesion layer, a metal body layer, and a metal passivation layer are sequentially formed to cover the surface of the patterned mask layer and fill the first opening;

[0013] Remove the patterned mask layer and its metal adhesion layer, metal body layer and metal passivation layer to expose the surface of the semiconductor substrate, and use the remaining metal adhesion layer, metal body layer and metal passivation layer in the first opening as the metal connector.

[0014] Optionally, the step of forming the polymer dielectric layer and performing the first curing includes:

[0015] A polymer dielectric layer is formed to cover the semiconductor substrate and the surface of the metal connector, and to fill the space above the metal connector;

[0016] A patterning process is performed on the polymer dielectric layer to form a second opening that exposes the top of the metal connector;

[0017] The polymer dielectric layer is subjected to a first curing process, wherein the curing temperature of the first curing process is lower than the glass transition temperature of the polymer dielectric layer, and the top surface of the first cured polymer dielectric layer is higher than or equal to the top surface of the metal connector.

[0018] Optionally, the polymer dielectric layer is a photosensitive polymer dielectric layer material, the polymer dielectric layer is formed by spin coating, and the patterning process is performed using the polymer dielectric layer as a photoresist.

[0019] Optionally, the polymer dielectric layer is made of PI material or BCB material.

[0020] Optionally, the height of the polymer medium layer formed beyond the metal connector is less than the sum of the heights of the polymer medium layer that shrink during the first curing and the second curing.

[0021] Optionally, before performing the hot-press bonding process, any of the following items may be included:

[0022] The surfaces of the first semiconductor structure and the second semiconductor structure were subjected to plasma treatment sequentially using argon, nitrogen and hydrogen.

[0023] Plasma treatment is performed on the surfaces of the first semiconductor structure and the second semiconductor structure using a mixture of argon, nitrogen and hydrogen gas;

[0024] The surfaces of the first semiconductor structure and the second semiconductor structure are treated with a weak acid immersion treatment.

[0025] Optionally, after performing the hot-press bonding, the bonded first semiconductor structure and the second semiconductor structure are further subjected to an annealing process, wherein the annealing temperature is greater than the glass transition temperature of the polymer dielectric layer.

[0026] According to another aspect of the present invention, a hybrid bonding structure is also provided, which is prepared by the hybrid bonding method described above.

[0027] In summary, this invention provides a hybrid bonding structure and bonding method. The hybrid bonding method includes: providing a first semiconductor structure and a second semiconductor structure to be bonded, wherein both the first semiconductor structure and the second semiconductor structure have a polymer dielectric layer and metal connectors embedded in the polymer dielectric layer on their surfaces; the method for forming the first semiconductor structure and / or the second semiconductor structure includes: providing a semiconductor substrate to be bonded; forming a plurality of protruding metal connectors on the semiconductor substrate; forming a polymer dielectric layer covering the surface of the semiconductor substrate and exposing the metal connectors; performing a first curing on the polymer dielectric layer, wherein the curing temperature of the first curing is lower than the glass transition temperature of the polymer dielectric layer, and the top surface of the polymer dielectric layer after the first curing is higher than or equal to the top surface of the metal connectors; performing hot-press bonding to connect the polymer dielectric layer and the metal connectors on the surfaces of the first semiconductor structure and the second semiconductor structure respectively, wherein the hot-press bonding process temperature is higher than the glass transition temperature of the polymer dielectric layer to perform a second curing on the polymer dielectric layer. In this invention, because the curing temperature of the first curing step is lower than the glass transition temperature of the polymer dielectric layer, the polymer dielectric layer is not completely cured after the first curing step. However, the polymer dielectric layer undergoes a certain degree of shrinkage during the first curing step, and the state of the polymer dielectric layer after the first curing step is relatively stable and can be directly used for subsequent bonding processes. On the other hand, the aforementioned incompletely cured polymer dielectric layer completes the remaining shrinkage during the second curing step in subsequent bonding, that is, the aforementioned polymer dielectric layer still has a certain degree of deformation during subsequent bonding, which can reduce the requirements for the surface morphology of the polymer dielectric layer before bonding (e.g., flatness requirements). Moreover, while ensuring that the curing temperature is lower than the glass transition temperature of the polymer dielectric layer, the curing temperature of the first curing step can be adjusted according to actual needs, thereby adjusting the height difference between the polymer dielectric layer and the metal connector. Therefore, compared with the chemical mechanical polishing process used in related technologies to control the height of the polymer medium layer, this application can control the height difference between the polymer medium layer and the metal connector before bonding by controlling the thickness of the polymer medium layer before the first curing and the curing temperature of the first curing. This avoids the need to use chemical mechanical polishing to control the height difference between the polymer medium layer and the metal connector, which not only simplifies the process and greatly reduces the difficulty of the process, but also makes it more conducive to realizing a high-density, narrow-pitch hybrid bonding structure (achieving high-density bonding). At the same time, it also helps to improve the overall reliability and production efficiency of the process. Attached Figure Description

[0028] Those skilled in the art will understand that the accompanying drawings are provided to better understand the invention and do not constitute any limitation on the scope of the invention.

[0029] Figure 1 This is a flowchart of a hybrid bonding method provided in an embodiment of the present invention.

[0030] Figures 2a to 2g This is a schematic diagram of the structure corresponding to the steps of the hybrid bonding method provided in an embodiment of the present invention.

[0031] In the attached figures: 10-semiconductor substrate; 11-patterned mask layer; 12-first opening; 13-metal adhesion layer; 14-metal host layer; 15-metal passivation layer; 16-metal connector; 21-polymer dielectric layer; 22-second opening. Detailed Implementation

[0032] To make the objectives, advantages, and features of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale, and are only used to facilitate and clarify the explanation of the embodiments of this invention. Furthermore, the structures shown in the drawings are often part of the actual structures. In particular, different figures may emphasize different aspects and may sometimes use different scales.

[0033] As used in this invention, the singular forms “a,” “an,” and “the” include plural objects; the term “or” is generally used to mean “and / or”; the term “a number” is generally used to mean “at least one”; and the term “at least two” is generally used to mean “two or more”. Furthermore, the terms “first,” “second,” and “third” are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as “first,” “second,” or “third” may explicitly or implicitly include one or at least two of that feature, unless otherwise expressly indicated.

[0034] This application provides a hybrid bonding method.

[0035] Figure 1 This is a flowchart of the hybrid bonding method provided in this embodiment.

[0036] like Figure 1 As shown, the hybrid bonding method provided in this embodiment includes:

[0037] S01: A first semiconductor structure and a second semiconductor structure to be bonded are provided. Both the first semiconductor structure and the second semiconductor structure have a polymer dielectric layer and metal connectors embedded in the polymer dielectric layer on their surfaces. A method for forming the first semiconductor structure and / or the second semiconductor structure includes: providing a semiconductor substrate to be bonded; forming a plurality of protruding metal connectors on the semiconductor substrate; forming a polymer dielectric layer covering the surface of the semiconductor substrate and exposing the metal connectors; performing a first curing on the polymer dielectric layer; wherein the curing temperature of the first curing is lower than the glass transition temperature of the polymer dielectric layer, and the top surface of the first cured polymer dielectric layer is higher than or equal to the top surface of the metal connectors.

[0038] S02: Perform thermocompression bonding to connect the polymer dielectric layer and metal connector on the surfaces of the first semiconductor structure and the second semiconductor structure respectively. The process temperature of the thermocompression bonding is higher than the glass transition temperature of the polymer dielectric layer, so that the polymer dielectric layer undergoes a second curing.

[0039] Figures 2a to 2g This is a schematic diagram of the structure corresponding to the steps of the hybrid bonding method provided in this embodiment. Next, we will combine... Figures 2a to 2g The hybrid bonding method is described in detail below.

[0040] First, step S01 is performed, providing a first semiconductor structure and a second semiconductor structure to be bonded. Both the first semiconductor structure and the second semiconductor structure have a polymer dielectric layer 21 and a metal connector 16 embedded in the polymer dielectric layer 21 on their surfaces.

[0041] The first semiconductor structure and the second semiconductor structure can be any suitable semiconductor substrate 10 for bonding, such as a wafer to be bonded, an interposer with through-silicon vias, a semi-finished chip to be bonded, or a finished chip to be bonded. The first semiconductor structure and the second semiconductor structure can be a matched pair, that is, a pair to be bonded together. Both the first semiconductor structure and the second semiconductor structure have a region to be bonded (the region used for bonding), and the region to be bonded has multiple interconnect structures (e.g., plugs or interconnects, not shown in the figure) for bonding.

[0042] In this design, multiple exposed metal connectors 16 are provided on the surfaces of the first and second semiconductor structures (the areas to be bonded), each electrically leading to a corresponding interconnect structure. A polymer dielectric layer 21 is filled between adjacent metal connectors 16 for electrical isolation. Each metal connector 16 may include a metal body layer 14 connected to the interconnect structure and a metal passivation layer 15 covering the metal body layer 14. The metal body layer 14 can be any suitable metal material with good conductivity, such as copper or aluminum. The metal passivation layer 15 is used to prevent oxidation of the top of the metal body layer 14, and is for example, a metal material with good conductivity and resistance to oxidation. Furthermore, a metal that can improve the diffusion activity of the metal on the top wall (bonding interface) of the metal body layer 14 can be selected as the metal passivation layer 15 to reduce the bonding process temperature; for example, gold, titanium, chromium, tin, or niobium. In addition to the metal body layer 14 and the metal passivation layer 15, the metal connector 16 also includes a metal adhesion layer 13 disposed between the interconnect structure and the metal body layer 14. In one example, the metal host layer 14 is made of aluminum, and the metal adhesion layer 13 may be made of titanium. In another example, the metal host layer 14 is made of copper, and a copper seed layer is provided between the metal host layer 14 and the interconnect structure. It is understood that the film structure and material of the metal connectors 16 on the first semiconductor structure and the second semiconductor structure may be the same or different.

[0043] In this application, the polymer dielectric layer 21 on at least one surface of the first semiconductor structure and the second semiconductor structure is not fully cured (partially cured), and the top surface of the not fully cured polymer dielectric layer 21 is higher than or equal to the top surface of the metal connector 16. The polymer dielectric layer 21 on the remaining (or possibly nonexistent) surface of the first and second semiconductor structures is fully cured, and the fully cured polymer dielectric layer 21 is lower than the top surface of the metal connector 16. In other words, in one example, both the first and second semiconductor structures have the aforementioned not fully cured polymer dielectric layer 21 on their surfaces; in another example, only one surface of the first and second semiconductor structures has the aforementioned not fully cured polymer dielectric layer 21, while the remaining surface has the aforementioned fully cured polymer dielectric layer 21.

[0044] For example, the steps of forming the metal connector 16 and the incompletely cured polymer dielectric layer 21 may include:

[0045] Please refer to Figure 2aA semiconductor substrate 10 is provided, and a patterned mask layer 11 is formed on the semiconductor substrate 10. The patterned mask layer 11 has a plurality of first openings 12 that expose portions of the surface of the semiconductor substrate 10. The patterned mask layer 11 may be a patterned photoresist layer, and the thickness of the patterned mask layer 11 may be matched with the height of the metal interconnect 16 to be formed, for example, 1.5 micrometers to 2 micrometers. The first openings 12 expose the interconnect structure to be electrically led out.

[0046] Please refer to Figure 2b A metal adhesion layer 13, a metal substrate layer 14, and a metal passivation layer 15 are sequentially formed to cover the surface of the patterned mask layer 11 and fill the first opening 12. The materials of each layer can refer to the previous description, and the metal adhesion layer 13, metal substrate layer 14, and metal passivation layer 15 can be formed sequentially, for example, using a physical vapor deposition process. Taking aluminum as an example, the metal substrate layer 14 can be formed sequentially using a physical vapor deposition process.

[0047] Please refer to Figure 2c Remove the patterned mask layer 11 and its metal adhesion layer 13, metal body layer 14 and metal passivation layer 15 to expose the surface of the semiconductor substrate 10, and use the remaining metal adhesion layer 13, metal body layer 14 and metal passivation layer 15 in the first opening 12 as metal connectors 16.

[0048] It should be noted that this application does not limit the structure and formation method of the protruding metal connector 16. In other examples of this application, the material of the metal body layer 14 may include, for example, copper. The steps of forming the metal connector 16 with copper as the metal body layer 14 may include: forming a copper seed layer covering the surface of the semiconductor substrate 10 using a physical vapor deposition process; then forming a patterned mask layer 11 as described above; then forming a copper layer filling the first opening 12 in the patterned mask layer 11 using a chemical electroplating process; then forming a metal passivation layer 15 using a physical vapor deposition process; then removing the patterned mask layer 11 and the films above and below it to expose the surface of the semiconductor substrate 10; and using the remaining copper seed layer, copper layer and metal passivation layer 15 in the first opening 12 as the metal connector 16.

[0049] Please refer to Figure 2dA polymer dielectric layer 21 is formed to cover the semiconductor substrate 10 and the metal connector 16, and to fill the area above the metal connector 16. The polymer dielectric layer 21 can be formed (filled) using a spin-coating process. The thickness of the filled polymer dielectric layer 21 is greater than the height of the metal connector 16. The thickness of the polymer dielectric layer 21 is controlled by the spin-coating process so that the height of the filled polymer dielectric layer 21 exceeding the metal connector 16 is less than the sum of the shrinkage heights of the polymer dielectric layer 21 during the first and second curing processes. Furthermore, the height of the filled polymer dielectric layer 21 exceeding the metal connector 16 is greater than or equal to the shrinkage height of the polymer dielectric layer 21 during the first curing process. In other words, it is ensured that the height of the polymer dielectric layer 21 after the first curing before bonding is greater than or equal to the height of the metal connector 16, and simultaneously, the height of the filled polymer dielectric layer 21 after the first curing before bonding and the second curing during bonding (the height after thermal shrinkage) is lower than the height of the metal connector 16. In one example of this application, the height of the metal connector 16 is 1.7 micrometers, the thickness of the uncured polymer medium layer 21 can be 2.3 micrometers to 2.6 micrometers, the thickness of the polymer medium layer 21 after the first curing is 1.7 micrometers to 1.9 micrometers, and the thickness of the polymer medium layer 21 after the first curing and the second curing is 1.5 micrometers to 1.6 micrometers.

[0050] Please refer to Figure 2e A patterning process is performed on the polymer dielectric layer 21 to form a second opening 22 exposing the top of the metal connector 16. As previously described, the polymer dielectric layer 21 can be a photosensitive polymer dielectric layer. A photolithography process is used to remove the polymer dielectric layer 21 above the metal connector 16, forming a second opening 22 in the polymer dielectric layer 21 to expose the surface of the metal connector 16. The cross-sectional shape of the second opening 22 can be the same as or similar to the cross-sectional shape of the metal connector 16, and the size of the second opening 22 can be slightly larger than the size of the metal connector 16. The photosensitive polymer dielectric layer can be made of PI (polyimide) or BCB (benzocyclobutene resin).

[0051] Please refer to Figure 2fThe polymer dielectric layer 21 undergoes a first curing process. The curing temperature of the first curing is lower than the glass transition temperature of the polymer dielectric layer 21, and the top surface of the polymer dielectric layer 21 after the first curing is higher than or equal to the top surface of the metal connector 16. Because the curing temperature of the first curing is lower than the glass transition temperature of the polymer dielectric layer 21, the polymer dielectric layer 21 is not completely cured after the first curing. However, the polymer dielectric layer 21 undergoes a certain degree of shrinkage during the first curing, and the top surface of the polymer dielectric layer 21 after the first curing is still higher than or equal to the top surface of the metal connector 16. The state of the polymer dielectric layer 21 after the first curing is relatively stable and can be directly used for subsequent bonding processes. On the other hand, the incompletely cured polymer dielectric layer 21 completes the remaining shrinkage during the second curing process during subsequent bonding. That is, the polymer dielectric layer 21 still possesses a certain degree of deformation during subsequent bonding, which can reduce the requirements for the surface morphology of the polymer dielectric layer 21 before bonding (e.g., flatness requirements). In addition, provided that the curing temperature is lower than the glass transition temperature of the polymer medium layer 21, that is, provided that the polymer medium layer 21 is not completely cured, the curing temperature of the first curing can be adjusted according to actual needs, thereby adjusting the height difference between the polymer medium layer 21 and the metal connector 16.

[0052] Therefore, compared with the chemical mechanical polishing process used in related technologies to control the height of the polymer medium layer 21, this application can control the height difference between the polymer medium layer 21 and the metal connector 16 before bonding by controlling the thickness of the polymer medium layer 21 before the first curing and the curing temperature of the first curing. This avoids the need to use the chemical mechanical polishing process to control the height difference between the polymer medium layer 21 and the metal connector 16, which not only simplifies the process flow and greatly reduces the process difficulty, but also makes it more conducive to realizing a high-density, narrow-pitch hybrid bonding structure (achieving high-density bonding). At the same time, it also helps to improve the overall process reliability and production efficiency.

[0053] In one example, the polymer dielectric layer can be made of PI material, which has a glass transition temperature of approximately 200°C, and the first curing temperature can be between 100°C and 200°C. In another example, the polymer dielectric layer can be made of BCB material, which has a glass transition temperature of approximately 350°C, and the first curing temperature can be between 150°C and 300°C.

[0054] Next, please refer to Figure 2g In step S02, hot-press bonding is performed to connect the polymer dielectric layer 21 and the metal connector 16 on the surfaces of the first semiconductor structure and the second semiconductor structure respectively. The hot-press bonding process temperature is higher than the glass transition temperature of the polymer dielectric layer, so that the polymer dielectric layer undergoes a second curing.

[0055] Before bonding, the first and second semiconductor structures to be bonded may undergo surface treatment to remove surface oxide layers and other impurities, thereby improving the surface activity of the exposed metal connector 16 and polymer dielectric layer 21 (top wall). The surface treatment may include any one or more of the following processes: sequentially applying plasma treatment to the surfaces of the first and second semiconductor structures using argon, nitrogen, and hydrogen; applying plasma treatment to the surfaces of the first and second semiconductor structures using a mixed gas of argon, nitrogen, and hydrogen; or immersing the surfaces of the first and second semiconductor structures in a weak acid solution.

[0056] During bonding, the first and second semiconductor structures are placed on the hot plate and hot press head of a thermocompression bonding apparatus, respectively. The first and second semiconductor structures are then aligned, and heating and pressurization are applied through the hot plate and hot press head for a period of time to connect the polymer dielectric layer 21 and metal connector 16 on the surfaces of the first and second semiconductor structures, thus achieving hybrid bonding. In one example, the polymer dielectric layer can be made of PI material, the process temperature during thermocompression bonding can be, for example, 200℃~350℃, the bonding pressure can be 1MPa~50MPa, and the holding time during thermocompression can be 10 minutes~120 minutes. In another example, after the above thermocompression bonding, the bonded first and second semiconductor structures are further annealed. The annealing temperature is higher than the glass transition temperature of the polymer dielectric layer 21, and the annealing time can be 20 minutes~120 minutes.

[0057] This application also provides a hybrid bonding structure, which is prepared using the hybrid bonding method described above.

[0058] In summary, this invention provides a hybrid bonding structure and bonding method. The hybrid bonding method includes: providing a first semiconductor structure and a second semiconductor structure to be bonded, wherein both the first semiconductor structure and the second semiconductor structure have a polymer dielectric layer and metal connectors embedded in the polymer dielectric layer on their surfaces; the method for forming the first semiconductor structure and / or the second semiconductor structure includes: providing a semiconductor substrate to be bonded; forming a plurality of protruding metal connectors on the semiconductor substrate; forming a polymer dielectric layer covering the surface of the semiconductor substrate and exposing the metal connectors; performing a first curing on the polymer dielectric layer, wherein the curing temperature of the first curing is lower than the glass transition temperature of the polymer dielectric layer, and the top surface of the polymer dielectric layer after the first curing is higher than or equal to the top surface of the metal connectors; performing hot-press bonding to connect the polymer dielectric layer and the metal connectors on the surfaces of the first semiconductor structure and the second semiconductor structure respectively, wherein the hot-press bonding process temperature is higher than the glass transition temperature of the polymer dielectric layer to perform a second curing on the polymer dielectric layer. In this invention, because the curing temperature of the first curing step is lower than the glass transition temperature of the polymer dielectric layer, the polymer dielectric layer is not completely cured after the first curing step. However, the polymer dielectric layer undergoes a certain degree of shrinkage during the first curing step, and the state of the polymer dielectric layer after the first curing step is relatively stable and can be directly used for subsequent bonding processes. On the other hand, the aforementioned incompletely cured polymer dielectric layer completes the remaining shrinkage during the second curing step in subsequent bonding, that is, the aforementioned polymer dielectric layer still has a certain degree of deformation during subsequent bonding, which can reduce the requirements for the surface morphology of the polymer dielectric layer before bonding (e.g., flatness requirements). Moreover, while ensuring that the curing temperature is lower than the glass transition temperature of the polymer dielectric layer, the curing temperature of the first curing step can be adjusted according to actual needs, thereby adjusting the height difference between the polymer dielectric layer and the metal connector. Therefore, compared with the chemical mechanical polishing process used in related technologies to control the height of the polymer medium layer, this application can control the height difference between the polymer medium layer and the metal connector before bonding by controlling the thickness of the polymer medium layer before the first curing and the curing temperature of the first curing. This avoids the need to use chemical mechanical polishing to control the height difference between the polymer medium layer and the metal connector, which not only simplifies the process and greatly reduces the difficulty of the process, but also makes it more conducive to realizing a high-density, narrow-pitch hybrid bonding structure (achieving high-density bonding). At the same time, it also helps to improve the overall reliability and production efficiency of the process.

[0059] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.

Claims

1. A hybrid bonding method, characterized in that, include: A first semiconductor structure and a second semiconductor structure to be bonded are provided. Both the first semiconductor structure and the second semiconductor structure have a polymer dielectric layer and metal connectors embedded in the polymer dielectric layer on their surfaces. A method for forming the first semiconductor structure and / or the second semiconductor structure includes: providing a semiconductor substrate to be bonded; forming a plurality of protruding metal connectors on the semiconductor substrate; forming a polymer dielectric layer covering the surface of the semiconductor substrate and exposing the metal connectors; and performing a first curing on the polymer dielectric layer, wherein the curing temperature of the first curing is lower than the glass transition temperature of the polymer dielectric layer, and the top surface of the first cured polymer dielectric layer is higher than or equal to the top surface of the metal connectors. Hot-press bonding is performed to connect the polymer dielectric layer and metal connector on the surfaces of the first semiconductor structure and the second semiconductor structure, respectively. The hot-press bonding process temperature is higher than the glass transition temperature of the polymer dielectric layer, so that the polymer dielectric layer undergoes a second curing.

2. The hybrid bonding method according to claim 1, characterized in that, Before bonding, at least one of the polymer dielectric layers on the surfaces of the first semiconductor structure and the second semiconductor structure is cured using the first curing process, and the metal connectors on the surfaces of the first semiconductor structure or the second semiconductor structure that are not cured using the first curing process protrude from the corresponding polymer dielectric layers.

3. The hybrid bonding method according to claim 1, characterized in that, The step of forming a plurality of protruding metal connectors on the semiconductor substrate includes: A patterned mask layer is formed on a semiconductor substrate, wherein the patterned mask layer has a plurality of first openings that expose portions of the semiconductor substrate; A metal adhesion layer, a metal body layer, and a metal passivation layer are sequentially formed to cover the surface of the patterned mask layer and fill the first opening; Remove the patterned mask layer and its metal adhesion layer, metal body layer and metal passivation layer to expose the surface of the semiconductor substrate, and use the remaining metal adhesion layer, metal body layer and metal passivation layer in the first opening as the metal connector.

4. The hybrid bonding method according to claim 1, characterized in that, The steps of forming a polymer dielectric layer and performing the first curing include: A polymer dielectric layer is formed to cover the semiconductor substrate and the surface of the metal connector, and to fill the space above the metal connector; A patterning process is performed on the polymer dielectric layer to form a second opening that exposes the top of the metal connector; The polymer dielectric layer is subjected to a first curing process, wherein the curing temperature of the first curing process is lower than the glass transition temperature of the polymer dielectric layer, and the top surface of the first cured polymer dielectric layer is higher than or equal to the top surface of the metal connector.

5. The hybrid bonding method according to claim 4, characterized in that, The polymer dielectric layer is a photosensitive polymer dielectric layer material, which is formed by spin coating and the patterning process is performed using the polymer dielectric layer as photoresist.

6. The hybrid bonding method according to claim 5, characterized in that, The polymer medium layer is made of PI or BCB material.

7. The hybrid bonding method according to claim 1, characterized in that, The height of the polymer medium layer formed by filling beyond the metal connector is less than the sum of the heights of the polymer medium layer that shrink during the first curing and the second curing.

8. The hybrid bonding method according to claim 1, characterized in that, Before performing the hot-press bonding process, any of the following items are also included: The surfaces of the first semiconductor structure and the second semiconductor structure were subjected to plasma treatment sequentially using argon, nitrogen and hydrogen. Plasma treatment is performed on the surfaces of the first semiconductor structure and the second semiconductor structure using a mixture of argon, nitrogen and hydrogen gas; The surfaces of the first semiconductor structure and the second semiconductor structure are treated with a weak acid immersion treatment.

9. The hybrid bonding method according to claim 1, characterized in that, After performing the hot-press bonding, the bonded first semiconductor structure and the second semiconductor structure are further subjected to an annealing process at a temperature greater than the glass transition temperature of the polymer dielectric layer.

10. A hybrid bonding structure, characterized in that, It is prepared by the hybrid bonding method as described in any one of claims 1 to 9.

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