Hybrid bonding structure and bonding method

Abstract

The invention provides a hybrid bonding structure and a bonding method, and the method comprises the steps: providing a first semiconductor structure and a second semiconductor structure to be bonded, and a method for forming the first semiconductor structure and / or the second semiconductor structure comprises the steps: providing a semiconductor substrate to be bonded, a plurality of protruding metal connecting pieces are formed on a semiconductor substrate, a polymer dielectric layer is formed to cover the surface of the semiconductor substrate and expose the metal connecting pieces, first curing is carried out on the polymer dielectric layer, and the curing temperature of the first curing is smaller than the glass-transition temperature of the polymer dielectric layer; the top surface of the first cured polymer dielectric layer is higher than or equal to the top surface of the metal connecting piece; and performing thermocompression bonding to connect the first semiconductor structure and the second semiconductor structure, wherein 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 is subjected to second curing. According to the invention, the hybrid bonding process can be optimized.

Description

Technical Field

[0001] The present invention relates to the technical field of integrated circuit manufacturing, and in particular to a hybrid bonding structure and a bonding method. Background Art

[0002] As people's requirements for electronic products develop towards miniaturization, multi-function, and environmental protection, many new technologies, new materials, and new designs have emerged. Planar semiconductor devices are scaled to smaller sizes by improving process technology, circuit design, programming algorithms, and manufacturing processes. However, as the feature size of semiconductor devices approaches the physical limit, planar processes and manufacturing technologies become challenging and expensive. Three-dimensional stacked semiconductor device architectures can solve the density limitations in some planar semiconductor devices.

[0003] Among the various technologies used to stack semiconductor substrates, hybrid bonding (heterogeneous bonding) has become the focus of current three-dimensional integration technology research and development because it simultaneously connects circuit leads during the bonding process. For the hybrid bonding process, since the electrical connection between wafers must be achieved while completing wafer bonding, the surface morphology of the bonded wafers has extremely high requirements (height difference and flatness, etc.).

[0004] Taking the hybrid bonding with polyimide as the dielectric layer as an example, its preparation process generally includes: forming a metal bump in the area to be bonded, then forming polyimide in the area to be bonded and completely solidifying it to the top of the metal bump, and then performing a chemical mechanical polishing (CMP) process on the solidified polyimide to adjust the surface morphology of the polyimide and the height difference between the polyimide and the metal bump. In the process of preparing the hybrid structure, it is necessary to use a CMP process to polish the surface, but according to the current industry requirements, the surface roughness of the polyimide after polishing by the CMP process is required to be less than 0.5nm to facilitate the bonding of the dielectric layer, and there are also high requirements for the height difference between the polyimide and the metal bump. Therefore, the above bonding method not only requires CMP equipment, but also has extremely high requirements for CMP equipment, which will greatly increase the difficulty of the entire preparation process. If the conditions of the above CMP process are not met, it will seriously affect the yield of bonding, the performance and reliability of the bonded product. Summary of the invention

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

[0006] In order to solve the above 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, wherein surfaces of the first semiconductor structure and the second semiconductor structure are both provided with a polymer dielectric layer and a metal connector embedded in the polymer dielectric layer. The method for forming the first semiconductor structure and / or the second semiconductor structure comprises: providing a semiconductor substrate to be bonded, forming a plurality of raised metal connectors on the semiconductor substrate, forming a polymer dielectric layer to cover the surface of the semiconductor substrate and expose the metal connectors, performing a first curing on the polymer dielectric layer, wherein the curing temperature of the first curing is less 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 connector;

[0008] Thermocompression bonding is performed to connect the polymer dielectric layers and metal connectors on the surfaces of the first semiconductor structure and the second semiconductor structure, respectively. The process temperature of the thermocompression bonding is greater than the glass transition temperature of the polymer dielectric layer to perform a second curing of the polymer dielectric layer.

[0009] Optionally, before bonding, at least one of the polymer dielectric layers on the surface of the first semiconductor structure and the second semiconductor structure is cured using the first curing method, and the metal connector on the surface of the first semiconductor structure or the second semiconductor structure that is not cured using the first curing method protrudes from the corresponding polymer dielectric layer.

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

[0011] Forming a patterned mask layer on a semiconductor substrate, wherein the patterned mask layer is provided with a plurality of first openings exposing a portion of the semiconductor substrate;

[0012] forming a metal adhesion layer, a metal main layer and a metal passivation layer in sequence to cover the surface of the patterned mask layer and fill the first opening;

[0013] The patterned mask layer and the metal adhesion layer, metal main layer and metal passivation layer thereon are removed to expose the surface of the semiconductor substrate, and the metal adhesion layer, the metal main layer and the metal passivation layer remaining in the first opening serve as the metal connector.

[0014] Optionally, the steps of forming the polymer medium layer and performing the first curing include:

[0015] Forming a polymer dielectric layer to cover the semiconductor substrate and the surface of the metal connector and fill the top of the metal connector;

[0016] Performing a patterning process on the polymer dielectric layer to form a second opening to expose the top of the metal connector;

[0017] A first curing is performed on the polymer dielectric layer, wherein a curing temperature of the first curing is lower than a glass transition temperature of the polymer dielectric layer, and a top surface of the polymer dielectric layer after the first curing is higher than or equal to a 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 a spin coating process, and the patterning process is performed using the polymer dielectric layer as a photoresist.

[0019] Optionally, the polymer medium layer is PI material or BCB material.

[0020] Optionally, the height of the polymer medium layer formed by filling and exceeding the metal connector is less than the sum of the heights of the polymer medium layer contracted during the first curing and the second curing.

[0021] Optionally, before performing the thermal compression bonding process, any of the following items is also included:

[0022] sequentially performing plasma treatment on the surfaces of the first semiconductor structure and the second semiconductor structure using argon, nitrogen and hydrogen;

[0023] Performing plasma treatment on the surfaces of the first semiconductor structure and the second semiconductor structure using a mixed gas of argon, nitrogen and hydrogen;

[0024] The surfaces of the first semiconductor structure and the second semiconductor structure are treated by soaking with weak acid.

[0025] Optionally, after performing the thermocompression bonding, an annealing treatment is further performed on the bonded first semiconductor structure and the second semiconductor structure, and the temperature of the annealing treatment is greater than the glass transition temperature of the polymer dielectric layer.

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

[0027] In summary, the present invention provides a hybrid bonding structure and a bonding method, the hybrid bonding method comprising: providing a first semiconductor structure and a second semiconductor structure to be bonded, the surfaces of the first semiconductor structure and the second semiconductor structure are both provided with a polymer dielectric layer and a metal connector embedded in the polymer dielectric layer, the method for forming the first semiconductor structure and / or the second semiconductor structure comprises: 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, the curing temperature of the first curing is less 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 connector; performing hot pressing bonding to connect the polymer dielectric layers and the metal connectors on the surfaces of the first semiconductor structure and the second semiconductor structure respectively, the process temperature of the hot pressing bonding is greater than the glass transition temperature of the polymer dielectric layer to perform a second curing on the polymer dielectric layer. In the present invention, since the curing temperature of the first curing is lower than the glass transition temperature of the polymer dielectric layer, the polymer dielectric layer is not completely cured after the first curing, but the polymer dielectric layer shrinks to a certain extent during the first curing. The polymer dielectric layer after the first curing is relatively stable and can be directly used in the subsequent bonding process. On the other hand, the polymer dielectric layer that is not completely cured completes the remaining shrinkage in the second curing during the subsequent bonding, that is, the polymer dielectric layer still has a certain amount of deformation during the subsequent bonding, which can reduce the requirements for the surface morphology of the polymer dielectric layer before bonding (such as the flatness requirement). Moreover, under the premise of ensuring that the curing temperature is lower than the glass transition temperature of the polymer dielectric layer, the curing temperature of the first curing can also be adjusted according to actual needs, thereby adjusting the height difference between the polymer dielectric layer and the metal connector. Therefore, compared with the related art that uses a chemical mechanical polishing process to control the height of the polymer dielectric layer, the present application can control the height difference between the polymer dielectric layer and the metal connector before bonding by controlling the thickness of the polymer dielectric layer before the first curing and the curing temperature of the first curing, thereby avoiding the use of a chemical mechanical polishing process to control the height difference between the polymer dielectric layer and the metal connector. This not only simplifies the process flow and greatly reduces the process difficulty, but is also more conducive to achieving a high-density, narrow-pitch hybrid bonding structure (to achieve high-density bonding), and is also beneficial to improving the reliability and production efficiency of the overall process. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Those skilled in the art should understand that the drawings are provided for a better understanding of the present invention, but do not constitute any limitation on the scope of the present invention.

[0029] Figure 1 It is a flow chart of a hybrid bonding method provided by one embodiment of the present invention.

[0030] Figure 2a to Figure 2g A schematic structural diagram corresponding to corresponding steps of a hybrid bonding method provided in one embodiment of the present invention.

[0031] In the accompanying drawings: 10 - semiconductor substrate; 11 - patterned mask layer; 12 - first opening; 13 - metal adhesion layer; 14 - metal main layer; 15 - metal passivation layer; 16 - metal connector; 21 - polymer dielectric layer; 22 - second opening. DETAILED DESCRIPTION

[0032] In order to make the purpose, advantages and features of the present invention clearer, the present invention is further described in detail below in conjunction with 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 conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In addition, the structure shown in the drawings is often a part of the actual structure. In particular, the emphasis of each drawing is different, and sometimes different scales are used.

[0033] As used in the present invention, the singular forms "one", "an", and "the" include plural objects, the term "or" is usually used to include the meaning of "and / or", the term "several" is usually used to include the meaning of "at least one", and the term "at least two" is usually used to include the meaning of "two or more". In addition, the terms "first", "second", and "third" are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Therefore, the features defined as "first", "second", and "third" may explicitly or implicitly include one or at least two of the features, unless the content clearly indicates otherwise.

[0034] An embodiment of the present application provides a hybrid bonding method.

[0035] Figure 1 It is a flow chart 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: providing a first semiconductor structure and a second semiconductor structure to be bonded, wherein surfaces of the first semiconductor structure and the second semiconductor structure are both provided with a polymer dielectric layer and a metal connector embedded in the polymer dielectric layer, and the method for forming the first semiconductor structure and / or the second semiconductor structure comprises: providing a semiconductor substrate to be bonded, forming a plurality of raised metal connectors on the semiconductor substrate, forming a polymer dielectric layer to cover the surface of the semiconductor substrate and expose 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 connector;

[0038] S02: Performing thermocompression bonding to connect the polymer dielectric layers and metal connectors on the surfaces of the first semiconductor structure and the second semiconductor structure, respectively. The process temperature of the thermocompression bonding is greater than the glass transition temperature of the polymer dielectric layer to perform a second curing of the polymer dielectric layer.

[0039] Figure 2a to Figure 2g The structural diagram corresponding to the corresponding steps of the hybrid bonding method provided in this embodiment is shown below. Figure 2a to Figure 2g The hybrid bonding method is described in detail.

[0040] First, step S01 is performed to provide a first semiconductor structure and a second semiconductor structure to be bonded. The surfaces of the first semiconductor structure and the second semiconductor structure are both provided with a polymer dielectric layer 21 and a metal connector 16 embedded in the polymer dielectric layer 21 .

[0041] The first semiconductor structure and the second semiconductor structure may 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, etc. The first semiconductor structure and the second semiconductor structure may be a matching pair, that is, the two are a pair to be bonded as one, and the first semiconductor structure and the second semiconductor structure both have a region to be bonded (a region for bonding), and the region to be bonded has a plurality of interconnect structures for bonding (such as plugs or interconnect lines, not shown in the figure).

[0042] Among them, a plurality of exposed metal connectors 16 are provided on the surface of the first semiconductor structure and the second semiconductor structure (area to be bonded), each electrically leading out the corresponding interconnection structure, and a polymer dielectric layer 21 is filled between adjacent metal connectors 16 for electrical isolation. The metal connector 16 may include a metal main layer 14 connected to the interconnection structure and a metal passivation layer 15 covering the metal main layer 14. The metal main layer 14 may be any suitable metal material with good conductivity, such as copper, aluminum, etc. The metal passivation layer 15 is used to prevent the top of the metal main layer 14 from being oxidized, for example, a metal material with good conductivity and not easy to oxidize. Further, a metal that can improve the diffusion activity of the metal on the top wall (bonding interface) of the metal main layer 14 can also be selected as the metal passivation layer 15 to reduce the bonding process temperature, such as gold, titanium, chromium, tin or niobium. In addition, in addition to the metal main layer 14 and the metal passivation layer 15, the metal connector 16 also has a metal adhesion layer 13 disposed between the interconnection structure and the metal main layer 14. In one example, the material of the metal main layer 14 is aluminum, and the metal adhesion layer 13 can be titanium. In another example, the material of the metal main layer 14 is copper, and a copper seed layer is provided between the metal main layer 14 and the interconnect structure. It can be understood that the film layer structure and material of the metal connector 16 on the first semiconductor structure and the second semiconductor structure can be the same or different.

[0043] In the present application, the polymer dielectric layer 21 on at least one surface of the first semiconductor structure and the second semiconductor structure is not completely cured (partially cured), and the top surface of the incompletely cured polymer dielectric layer 21 is higher than or equal to the top surface of the metal connector 16, while the polymer dielectric layer 21 on the remaining one (or possibly non-existent) surface of the first semiconductor structure and the second semiconductor structure is completely cured, and the top surface of the completely cured polymer dielectric layer 21 is lower than the top surface of the metal connector 16. In other words, in one example, the surfaces of the first semiconductor structure and the second semiconductor structure are both the incompletely cured polymer dielectric layer 21; in another example, only one surface of the first semiconductor structure and the second semiconductor structure is the incompletely cured polymer dielectric layer 21, and the remaining one surface of the two is the completely 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 2a, a semiconductor substrate 10 is provided, and a patterned mask layer 11 is formed on the semiconductor substrate 10, wherein a plurality of first openings 12 are provided in the patterned mask layer 11 to expose a portion 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 match the height of the metal connector 16 to be formed, for example, 1.5 microns to 2 microns, and the first openings 12 expose the interconnection structure to be electrically led out.

[0046] Please refer to Figure 2b , a metal adhesion layer 13, a metal main layer 14 and a metal passivation layer 15 are formed in sequence to cover the surface of the patterned mask layer 11 and fill the first opening 12. The materials of the above-mentioned layers can refer to the above, and the metal adhesion layer 13, the metal main layer 14 and the metal passivation layer 15 can be formed in sequence by, for example, a physical vapor deposition process. Taking the material of the metal main layer 14 as aluminum as an example, the above-mentioned film layers can be formed in sequence by a physical vapor deposition process.

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

[0048] It should be noted that the present application does not limit the structure and formation method of the raised metal connector 16. In other examples of the present application, the material of the metal main layer 14 may include copper, for example, and the steps of forming the metal connector 16 with copper as the metal main layer 14 may include: using a physical vapor deposition process to form a copper seed layer to cover the surface of the semiconductor substrate 10, then forming a patterned mask layer 11 as described above, and then using a chemical electroplating process to form a copper layer to fill the first opening 12 in the patterned mask layer 11, then using a physical vapor deposition process to form a metal passivation layer 15, and then removing the patterned mask layer 11 and the film layers 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 2d, forming a polymer dielectric layer 21 to cover the semiconductor substrate 10 and the metal connector 16, and filling it above the metal connector 16. The polymer dielectric layer 21 can be formed (filled) by a spin coating process, and the thickness of the filled polymer dielectric layer 21 is higher than the height of the metal connector 16, and 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 heights of the polymer dielectric layer 21 contracted during the first curing and the second curing, and the height of the filled polymer dielectric layer 21 exceeding the metal connector 16 is greater than or equal to the height of the polymer dielectric layer 21 contracted during the first curing, in other words, it is ensured that the height of the above-mentioned polymer dielectric layer 21 after the first curing before bonding is greater than or equal to the height of the metal connector 16, and at the same time, the height of the filled polymer dielectric layer 21 after the first curing before bonding and the second curing during bonding (the height after heat shrinkage) is lower than the height of the metal connector 16. In one example of the present application, the height of the metal connector 16 is 1.7 microns, the thickness of the uncured polymer medium layer 21 can be 2.3 microns to 2.6 microns, the thickness of the polymer medium layer 21 after the first curing is 1.7 microns to 1.9 microns, and the thickness of the polymer medium layer 21 after the first and second curing is 1.5 microns to 1.6 microns.

[0050] Please refer to Figure 2e , a patterning process is performed on the polymer dielectric layer 21 to form a second opening 22 to expose the top of the metal connector 16. As shown above, the polymer dielectric layer 21 can be a photosensitive polymer dielectric layer, and the polymer dielectric layer 21 above the metal connector 16 is removed by a photolithography process, and a second opening 22 is formed 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. Among them, the photosensitive polymer dielectric layer can be a PI (polyimide) material or a BCB (benzocyclobutene resin) material.

[0051] Please refer to Figure 2f, the polymer dielectric layer 21 is first cured, 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. Since 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, but the polymer dielectric layer 21 shrinks to a certain extent 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 polymer dielectric layer 21 after the first curing is relatively stable and can be directly used in the subsequent bonding process. On the other hand, the polymer dielectric layer 21 that is not completely cured completes the remaining shrinkage in the second curing during the subsequent bonding, that is, the polymer dielectric layer 21 still has a certain deformation amount during the subsequent bonding, which can reduce the requirements for the surface morphology of the polymer dielectric layer 21 before bonding (such as the flatness requirement). In addition, under the premise of ensuring that the curing temperature is lower than the glass transition temperature of the polymer medium layer 21 , that is, ensuring that the polymer medium layer 21 is not completely cured, the curing temperature of the first curing can be adjusted according to actual needs to adjust the height difference between the polymer medium layer 21 and the metal connector 16 .

[0052] Therefore, compared with the related art that uses a chemical mechanical polishing process to control the height of the polymer dielectric layer 21, the present application can control the height difference between the polymer dielectric layer 21 and the metal connector 16 before bonding by controlling the thickness of the polymer dielectric layer 21 before the first curing and the curing temperature of the first curing, thereby avoiding the use of a chemical mechanical polishing process to control the height difference between the polymer dielectric layer 21 and the metal connector 16. This not only simplifies the process flow and greatly reduces the process difficulty, but is also more conducive to achieving a high-density, narrow-pitch hybrid bonding structure (to achieve high-density bonding), and is also beneficial to improving the reliability and production efficiency of the overall process.

[0053] In one example, the material of the polymer medium layer may be PI material, the glass transition temperature of the PI material is about 200° C., and the first curing temperature may be 100° C. to 200° C. In another example, the material of the polymer medium layer may be BCB material, the glass transition temperature of the BCB material is about 350° C., and the first curing temperature may be 150° C. to 300° C.

[0054] Next, please refer to Figure 2g , execute step S02, perform hot compression bonding to connect the polymer dielectric layer 21 and the metal connector 16 on the surface of the first semiconductor structure and the second semiconductor structure respectively, and the process temperature of the hot compression bonding is greater than the glass transition temperature of the polymer dielectric layer to perform a second curing of the polymer dielectric layer.

[0055] Before bonding, the first semiconductor structure and the second semiconductor structure to be bonded may be subjected to surface treatment to remove the surface oxide layer and other impurities, so as to improve the surface activity of the exposed metal connector 16 and the polymer dielectric layer 21 (top wall). The surface treatment may include any one or more of the following processes: sequentially performing plasma treatment on the surfaces of the first semiconductor structure and the second semiconductor structure using argon, nitrogen and hydrogen; performing plasma treatment on the surfaces of the first semiconductor structure and the second semiconductor structure using a mixed gas of argon, nitrogen and hydrogen; and performing weak acid immersion treatment on the surfaces of the first semiconductor structure and the second semiconductor structure.

[0056] When performing bonding, the first semiconductor structure and the second semiconductor structure can be placed on a hot plate and a hot pressing head of a hot pressing bonding device, and then the first semiconductor structure and the second semiconductor structure are aligned, and the hot plate and the hot pressing head are used to heat, pressurize and maintain for a period of time so that the polymer dielectric layer 21 and the metal connector 16 on the surface of the first semiconductor structure and the second semiconductor structure are respectively connected to achieve hybrid bonding. In one example, the material of the polymer dielectric layer can be PI material, the process temperature during hot pressing bonding can be, for example, 200°C to 350°C, the bonding pressure can be 1MPa to 50MPa, and the holding time of hot pressing can be 10 minutes to 120 minutes. In another example, after the above-mentioned hot pressing bonding, the bonded first semiconductor structure and the second semiconductor structure are also annealed, the temperature of the annealing treatment is greater than the glass transition temperature of the polymer dielectric layer 21, and the annealing time can be 20 minutes to 120 minutes.

[0057] The embodiment of the present application also provides a hybrid bonding structure, which is prepared by the above-mentioned hybrid bonding method.

[0058] In summary, the present invention provides a hybrid bonding structure and a bonding method, the hybrid bonding method comprising: providing a first semiconductor structure and a second semiconductor structure to be bonded, the surfaces of the first semiconductor structure and the second semiconductor structure are both provided with a polymer dielectric layer and a metal connector embedded in the polymer dielectric layer, the method for forming the first semiconductor structure and / or the second semiconductor structure comprises: 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, the curing temperature of the first curing is less 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 connector; performing hot pressing bonding to connect the polymer dielectric layers and the metal connectors on the surfaces of the first semiconductor structure and the second semiconductor structure respectively, the process temperature of the hot pressing bonding is greater than the glass transition temperature of the polymer dielectric layer to perform a second curing on the polymer dielectric layer. In the present invention, since the curing temperature of the first curing is lower than the glass transition temperature of the polymer dielectric layer, the polymer dielectric layer is not completely cured after the first curing, but the polymer dielectric layer shrinks to a certain extent during the first curing. The polymer dielectric layer after the first curing is relatively stable and can be directly used in the subsequent bonding process. On the other hand, the polymer dielectric layer that is not completely cured completes the remaining shrinkage in the second curing during the subsequent bonding, that is, the polymer dielectric layer still has a certain amount of deformation during the subsequent bonding, which can reduce the requirements for the surface morphology of the polymer dielectric layer before bonding (such as the flatness requirement). Moreover, under the premise of ensuring that the curing temperature is lower than the glass transition temperature of the polymer dielectric layer, the curing temperature of the first curing can also be adjusted according to actual needs, thereby adjusting the height difference between the polymer dielectric layer and the metal connector. Therefore, compared with the related art that uses a chemical mechanical polishing process to control the height of the polymer dielectric layer, the present application can control the height difference between the polymer dielectric layer and the metal connector before bonding by controlling the thickness of the polymer dielectric layer before the first curing and the curing temperature of the first curing, thereby avoiding the use of a chemical mechanical polishing process to control the height difference between the polymer dielectric layer and the metal connector. This not only simplifies the process flow and greatly reduces the process difficulty, but is also more conducive to achieving a high-density, narrow-pitch hybrid bonding structure (to achieve high-density bonding), and is also beneficial to improving the reliability and production efficiency of the overall process.

[0059] The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of protection 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, wherein surfaces of the first semiconductor structure and the second semiconductor structure are both provided with a polymer dielectric layer and a metal connector embedded in the polymer dielectric layer. The method for forming the first semiconductor structure and / or the second semiconductor structure comprises: providing a semiconductor substrate to be bonded, forming a plurality of raised metal connectors on the semiconductor substrate, forming a polymer dielectric layer to cover the surface of the semiconductor substrate and expose the metal connectors, performing a first curing on the polymer dielectric layer, wherein the curing temperature of the first curing is less 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 connector; Thermocompression bonding is performed to connect the polymer dielectric layers and metal connectors on the surfaces of the first semiconductor structure and the second semiconductor structure, respectively. The process temperature of the thermocompression bonding is greater than the glass transition temperature of the polymer dielectric layer to perform a second curing of the polymer dielectric layer.

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 method, 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 method protrude from the corresponding polymer dielectric layer.

3. The hybrid bonding method according to claim 1, characterized in that: The step of forming a plurality of raised metal connectors on the semiconductor substrate comprises: Forming a patterned mask layer on a semiconductor substrate, wherein the patterned mask layer is provided with a plurality of first openings exposing a portion of the semiconductor substrate; forming a metal adhesion layer, a metal main layer and a metal passivation layer in sequence to cover the surface of the patterned mask layer and fill the first opening; The patterned mask layer and the metal adhesion layer, metal main layer and metal passivation layer thereon are removed to expose the surface of the semiconductor substrate, and the metal adhesion layer, the metal main layer and the metal passivation layer remaining in the first opening serve 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: Forming a polymer dielectric layer to cover the semiconductor substrate and the surface of the metal connector and fill the top of the metal connector; Performing a patterning process on the polymer dielectric layer to form a second opening to expose the top of the metal connector; A first curing is performed on the polymer dielectric layer, wherein a curing temperature of the first curing is lower than a glass transition temperature of the polymer dielectric layer, and a top surface of the polymer dielectric layer after the first curing is higher than or equal to a top surface of the metal connector.

5. The hybrid bonding method according to claim 1, characterized in that: The polymer dielectric layer is a photosensitive polymer dielectric layer material, is formed by a spin coating process, and is used as a photoresist to perform the patterning process.

6. The hybrid bonding method according to claim 5, characterized in that: The polymer medium layer is PI material 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 and exceeding the metal connecting piece is less than the sum of the heights of the polymer medium layer contracted during the first curing and the second curing.

8. The hybrid bonding method according to claim 1, characterized in that: Before performing the thermal compression bonding process, any of the following items may also be included: sequentially performing plasma treatment on the surfaces of the first semiconductor structure and the second semiconductor structure using argon, nitrogen and hydrogen; Performing plasma treatment on the surfaces of the first semiconductor structure and the second semiconductor structure using a mixed gas of argon, nitrogen and hydrogen; The surfaces of the first semiconductor structure and the second semiconductor structure are treated by soaking with weak acid.

9. The hybrid bonding method according to claim 1, characterized in that: After performing the thermocompression bonding, an annealing process is further performed on the bonded first semiconductor structure and the second semiconductor structure, and the temperature of the annealing process is greater than the glass transition temperature of the polymer dielectric layer.

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

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