Laser-assisted hybrid bonding interconnection method

Abstract

The invention relates to the technical field of hybrid bonding, in particular to a laser-assisted hybrid bonding interconnection method, which comprises the following steps of: S1, processing the surface of a wafer to enable the to-be-bonded surface of the wafer to be flat; s2, cleaning a to-be-bonded surface of the wafer, and removing organic pollutants and an oxide layer; s3, aligning and fitting the surfaces to be bonded of the two wafers; s4, enabling the to-be-bonded surfaces to comprise dielectric layers and metal interconnection points, irradiating the dielectric layers with infrared laser, and carrying out the interconnection of the dielectric layers of the two to-be-bonded surfaces; and S5, the metal interconnection points are heated by blue laser, and the metal interconnection points of the two surfaces to be bonded are interconnected. In the hybrid bonding stage, the infrared laser and the blue laser are used for bonding the dielectric layer and the metal interconnection point respectively, partitioned irradiation and differentiated heating of the metal interconnection point and the dielectric layer are achieved, the problems of interface warping, microcracks and other thermal damage are effectively avoided, and the interconnection quality and the packaging reliability are improved.

Description

Technical Field

[0001] This invention relates to the field of hybrid bonding technology, and more particularly to a laser-assisted hybrid bonding interconnection method. Background Technology

[0002] With the rapid development of 3D integration and Chiplet heterogeneous integration technologies, hybrid bonding has attracted widespread attention as a key interconnection method for achieving high-density, high-performance packaging. Hybrid bonding technology achieves copper-copper interconnects and Si-O-Si covalent bonding of the dielectric layer in the same bonding process, exhibiting excellent electrical performance and structural stability.

[0003] In existing technologies, hybrid bonding often employs uniform temperature bonding conditions, typically performing simultaneous bonding of copper interconnects and dielectric layers at temperatures exceeding 250°C or even 300°C. For example, the hybrid bonding method and structure disclosed in CN118969730A align the bonding faces of the first and second semiconductor structures before annealing at 250°C-350°C for 60-120 minutes. This hybrid bonding method easily leads to interface warping, stress concentration, microcracks, and bonding defects due to the difference in thermal expansion coefficients (CTE) between copper and silicon dioxide, severely impacting packaging reliability and yield. Furthermore, high-temperature processes hinder the compatible integration of temperature-sensitive materials, limiting their application in heterogeneous packaging.

[0004] Currently, there are also laser-assisted local heating bonding technologies, such as the bonding tool of the flip-chip laser bonding equipment disclosed in CN117497432A, which uses a radiating laser beam to bond semiconductor chips and substrates. CN 117790388A discloses a laser-assisted bonding method, system, and semiconductor equipment for chips, which selects appropriate laser data according to the chip type to bond the chip to be bonded and the substrate. It is evident that although laser-assisted bonding technology can achieve localized heating and reduce the overall thermal budget, existing solutions mostly use single-wavelength irradiation and are for bonding between the chip and the substrate. This makes it difficult to consider the different absorption characteristics of the metal interconnects and the dielectric layer for different laser wavelengths, hindering precise regional and temperature control and preventing its application in hybrid bonding between wafers.

[0005] In view of this, there is an urgent need for a laser-assisted hybrid bonding method to solve the failure problem caused by thermal mismatch in existing processes and improve interconnect quality and packaging reliability. Summary of the Invention

[0006] The purpose of this invention is to propose a laser-assisted hybrid bonding interconnect method, in which infrared laser and blue laser are used to bond the dielectric layer and metal interconnect points respectively during the hybrid bonding stage, so as to achieve partitioned irradiation and differentiated heating of the metal interconnect points and dielectric layer, effectively avoiding interface warping, microcracks and other thermal damage problems, and improving interconnect quality and packaging reliability.

[0007] It can achieve copper-copper metallurgical bonding and covalent bonding of dielectric layers under low temperature conditions, so as to solve the failure problem caused by thermal mismatch in existing processes and improve interconnect quality and packaging reliability.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] A laser-assisted hybrid bonding interconnect method includes the following steps:

[0010] S1. Process the wafer surface to make the bonding surface of the wafer flat;

[0011] S2. Clean the bonding surfaces of the wafer to remove organic contaminants and oxide layers; then,

[0012] S3. Align and bond the two wafers to be bonded.

[0013] S4. The bonding surfaces include a dielectric layer and metal interconnects. The dielectric layer is irradiated with an infrared laser to interconnect the dielectric layers of the two bonding surfaces.

[0014] S5. Use a blue laser to heat the metal interconnect points and interconnect the metal interconnect points on the two surfaces to be bonded.

[0015] Furthermore, in step S4, the material of the dielectric layer is silicon dioxide, and the dielectric layer is irradiated with an infrared laser with a wavelength of approximately 980 nm;

[0016] In step S5, the metal interconnect is a copper interconnect, which is heated by a blue laser with a wavelength of approximately 370 nm.

[0017] Furthermore, in step S4, during the process of irradiating the dielectric layer with infrared laser, the temperature of the dielectric layer is monitored and kept ≤100℃.

[0018] In step S5, during the process of heating the metal interconnects with a blue laser, the temperature of the metal interconnects is monitored to keep the temperature of the area where the metal interconnects are located ≤270℃.

[0019] Furthermore, in steps 4 and 5, the temperature of the dielectric layer and the metal interconnect is obtained using multiple temporarily attached miniature thermocouples.

[0020] The spacing between two adjacent micro thermocouples is 5-10 μm, and the temperature feedback response time of the micro thermocouple is ≤10 ms.

[0021] Furthermore, in step 4, the infrared laser spot size is 10-50 μm, the power is 2-10 W, and the pulse time is 100-500 ms;

[0022] In step 5, the size of the blue laser spot is 1-10μm, the power is 10-30W, and the pulse time is 10-100ms.

[0023] Furthermore, in step 4, the dwell time of the infrared laser irradiation medium layer is 100–300 ms;

[0024] In step 5, the dwell time of the blue laser irradiating the metal interconnect is 50-100ms.

[0025] Furthermore, in step 4, after the wafer is covered with the first mask, the dielectric layer is irradiated with an infrared laser to interconnect the dielectric layers of the two surfaces to be bonded, and then the first mask is removed.

[0026] In step 5, after the wafer is covered with the second mask, the metal interconnect points are heated by a blue laser, and the metal interconnect points of the two surfaces to be bonded are interconnected before the second mask is removed.

[0027] Furthermore, in steps S4 and S5, the same laser generator is used to perform laser interconnection on the dielectric layer and the metal interconnect points. The laser emits infrared laser and blue laser through an optical module with nonlinear frequency conversion.

[0028] Furthermore, in step S1, chemical mechanical polishing is used to process the bonding surface of the wafer so that the height difference between the dielectric layer and the metal interconnect is less than 5 nm.

[0029] Furthermore, in step S2, plasma activation is used to remove organic contaminants from the wafer bonding surface and enhance surface activity, followed by chemical cleaning of the wafer to remove the oxide layer from the bonding surface.

[0030] The technical solution provided by this invention may include the following beneficial effects:

[0031] In this invention, during hybrid bonding, infrared lasers penetrate the wafer to reach the dielectric layer, locally heating it and promoting bonding. Blue laser light is absorbed by the metal and locally heated, triggering atomic diffusion and forming metallurgical bonds. This localized heating method effectively avoids interface warping, microcracks, and other thermal damage. Furthermore, laser localized heating offers rapid response and concentrated energy; combined with mask design, the irradiation area can be precisely controlled, improving process stability and repeatability, and providing excellent thermal stress control and process compatibility. This method requires no additional auxiliary materials or complex processes and is suitable for advanced packaging fields with extremely high requirements for interconnect strength and thermal management, such as high-performance computing, optoelectronic integration, and heterogeneous system packaging. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of dielectric layer bonding in a laser-assisted hybrid bonding interconnect method according to an embodiment of the present invention;

[0033] Figure 2 This is a schematic diagram of metal interconnect point bonding in a laser-assisted hybrid bonding interconnect method according to an embodiment of the present invention;

[0034] Among them, optical module 1, lens 2, infrared laser 3, wafer 4, dielectric layer 5, metal interconnect 6, blue laser 7, and mask 8. Detailed Implementation

[0035] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the present invention.

[0036] A laser-assisted hybrid bonding interconnection method according to an embodiment of the present invention includes the following steps:

[0037] S1. Process the wafer surface to make the bonding surface of the wafer flat;

[0038] S2. Clean the bonding surfaces of the wafer to remove organic contaminants and oxide layers;

[0039] S3. Align and bond the two wafers to be bonded.

[0040] S4. The surfaces to be bonded include a dielectric layer and metal interconnect points. An infrared laser is used to irradiate the dielectric layer, interconnecting the dielectric layers of the two surfaces to be bonded. Afterwards...

[0041] S5. Use a blue laser to heat the metal interconnect points and interconnect the metal interconnect points on the two surfaces to be bonded.

[0042] In this invention, during hybrid bonding, infrared lasers penetrate the wafer to reach the dielectric layer, locally heating it and promoting bonding. Blue laser light is absorbed by the metal and locally heated, triggering atomic diffusion and forming metallurgical bonds. This localized heating method effectively avoids interface warping, microcracks, and other thermal damage. Furthermore, laser localized heating offers rapid response and concentrated energy; combined with mask design, the irradiation area can be precisely controlled, improving process stability and repeatability, and providing excellent thermal stress control and process compatibility. This method requires no additional auxiliary materials or complex processes and is suitable for advanced packaging fields with extremely high requirements for interconnect strength and thermal management, such as high-performance computing, optoelectronic integration, and heterogeneous system packaging.

[0043] Specifically, in step S1, the bonding surface of the wafer is flattened, ensuring the surfaces of the dielectric layer and metal interconnects are smooth, thus reducing roughness. Step S2 further processes the bonding surface to improve the bonding quality at the interface. In step S3, a hybrid bonding alignment technique is employed, with bonding performed in a vacuum or inert atmosphere, ensuring appropriate bonding pressure and alignment accuracy to avoid contamination and bubble formation. In steps S4 and S5, the sequence of regional laser-assisted bonding is as follows: infrared laser first irradiates the dielectric layer, followed by blue laser irradiating the metal interconnects. Heating the metal interconnects first can cause micro-warping due to thermal expansion of the metal, negatively impacting the uniformity of subsequent dielectric layer bonding; furthermore, heating the metal interconnects first can easily cause the overall structure to enter a thermal cycle, leading to cracks in the dielectric region or increased residual stress.

[0044] Compared to the mismatch in thermal expansion coefficients caused by uniform heating of both materials in traditional hybrid bonding processes, this invention optimizes local temperature conditions separately. It maintains the metal interconnect region at a higher temperature suitable for metallurgical diffusion, while keeping the dielectric layer region at a lower temperature, effectively preventing interface warping, microcracks, and other thermal damage. This method lowers the overall bonding temperature while ensuring the compactness of the intermetallic bond and the formation of non-metallic covalent bonds, thus improving interfacial bonding strength and encapsulation reliability.

[0045] In one embodiment of the present invention, in step S4, the material of the dielectric layer is silicon dioxide, and the dielectric layer is irradiated with an infrared laser with a wavelength of approximately 980 nm.

[0046] In step S5, the metal interconnect is a copper interconnect, which is heated by a blue laser with a wavelength of approximately 370 nm.

[0047] The dielectric layer exhibits good absorption in the near-infrared band, and the SiO2 dielectric layer can achieve shallow absorption under 980nm infrared laser light. 980nm wavelength light can be absorbed by hydroxyl groups (–OH) near the dielectric surface, initiating a Si–OH condensation reaction, ultimately forming a strong covalent bond Si–O–Si, resulting in a strong bond between the two dielectric layers. Longer laser wavelengths result in greater penetration depth and gentler heating; 980nm infrared laser light does not significantly affect the metal interconnect points, enabling selective localized heating. Furthermore, 980nm industrial laser devices are mature, low-cost, and highly stable. Blue laser light (370nm) is absorbed by copper and locally heated, triggering copper atom diffusion and forming metallurgical bonds. The principle is to heat the material according to its absorption peaks, avoiding thermal stress mismatch caused by overall heating, while simultaneously promoting the simultaneous development of chemical and metallurgical bonds, thus improving the overall bonding strength.

[0048] Furthermore, in step S4, during the process of irradiating the dielectric layer with infrared laser, the temperature of the dielectric layer is monitored and kept ≤100℃.

[0049] In step S5, during the process of heating the metal interconnects with a blue laser, the temperature of the metal interconnects is monitored to keep the temperature of the area where the metal interconnects are located ≤270℃.

[0050] Preferably, in steps 4 and 5, the temperature of the dielectric layer and the metal interconnect is obtained using multiple temporarily attached miniature thermocouples;

[0051] The spacing between two adjacent micro thermocouples is 5-10 μm, and the temperature feedback response time of the micro thermocouple is ≤10 ms.

[0052] During laser-assisted hybrid bonding, real-time temperature monitoring utilizes multiple temporarily mounted miniature thermocouples, which are removed after bonding is complete. Laser power is dynamically adjusted based on temperature to ensure the temperature at the metal interconnect points is ≤270℃ and the dielectric layer temperature is ≤100℃, preventing interface warping and cracking due to thermal mismatch. The spacing between adjacent miniature thermocouples is set to 5-10μm based on the blue laser spot size between 1–10μm, allowing the thermocouples to accurately cover multiple interconnect and dielectric regions, closely mimicking actual thermal field changes.

[0053] Specifically, miniature thermocouples are mounted on the wafer surface. Due to the small wafer thickness, the thermocouples can provide a localized approximate temperature of the bonding area. Compared to laser temperature measurement, thermocouple temperature measurement offers higher accuracy. Miniature thermocouples monitor the thermal field distribution caused by laser irradiation in real time, accurately distinguishing local temperature changes between metal interconnects and dielectric layers. This provides support for laser power feedback adjustment, controlling the temperature during metal interconnect bonding to ≤270℃ and the temperature during dielectric layer bonding to ≤100℃. This effectively avoids interface warping, cracking, and bubble problems caused by thermal mismatch, improving interconnect interface stability and packaging yield.

[0054] In one embodiment of the present invention, in step 4, the infrared laser spot size is 10-50 μm, the power is 2-10 W, and the pulse time is 100-500 ms;

[0055] In step 5, the size of the blue laser spot is 1-10μm, the power is 10-30W, and the pulse time is 10-100ms.

[0056] Infrared lasers with a spot size of 10-50 μm, covering the entire dielectric layer region, with a power of 2-10 W and a pulse duration of 100-500 ms, can heat the dielectric layer to assist in the formation of Si-O-Si covalent bonds. Blue lasers with a spot size of 1-10 μm, acting locally on the metal interconnect points, with a power of 10-30 W and a pulse duration of 10-100 ms, avoid thermal diffusion that could affect the stability of the dielectric layer.

[0057] Furthermore, in step 4, the dwell time of the infrared laser irradiation medium layer is 100–300 ms;

[0058] In step 5, the dwell time of the blue laser irradiating the metal interconnect is 50-100ms.

[0059] When irradiating the dielectric layer with a 980nm infrared laser at a bonding temperature ≤270℃, the dwell time is limited to 100–300ms. Too short a time prevents complete removal of Si–OH groups, while too long a time may cause heat diffusion to adjacent areas, leading to localized thermal stress or warping. For irradiating the metal interconnect region with a 370nm blue laser at a temperature ≤270℃, the dwell time is limited to 50–100ms. Too short a time prevents complete metallurgical bonding, while too long a time damages the surrounding dielectric layer.

[0060] Preferably, in step 4, after the wafer is covered with the first mask, the dielectric layer is irradiated with an infrared laser to interconnect the dielectric layers of the two surfaces to be bonded, and then the first mask is removed.

[0061] In step 5, after the wafer is covered with the second mask, the metal interconnect points are heated by a blue laser, and the metal interconnect points of the two surfaces to be bonded are interconnected before the second mask is removed.

[0062] This invention, combined with mask design, can precisely control the irradiation area, improve process stability and repeatability, and has excellent thermal stress control and process compatibility.

[0063] Preferably, in steps S4 and S5, the same laser generator is used to perform laser interconnection on the dielectric layer and the metal interconnect points. The laser emits infrared and blue lasers through an optical module with nonlinear frequency conversion. This invention uses a single light source with beam splitting to obtain lasers of different wavelengths, achieving zoned irradiation and differentiated heating of the metal interconnect points and the dielectric layer, simplifying the hybrid bonding process. It should be noted that this invention can achieve the emission of infrared and blue lasers using existing lasers and optical modules.

[0064] Preferably, in step S1, chemical mechanical polishing is used to treat the bonding surface of the wafer so that the height difference between the dielectric layer and the metal interconnect is less than 5nm, so as to ensure reliable bonding after the metal interconnect is thermally expanded during bonding.

[0065] Preferably, in step S2, plasma activation is used to remove organic contaminants from the wafer's bonding surfaces and enhance surface activity, followed by chemical cleaning to remove the oxide layer from the bonding surfaces. Through plasma activation and chemical cleaning, hydroxyl (–OH) groups can be introduced into the bonding surfaces, improving hydrophilicity. Removing organic impurities and the oxide layer from the bonding surfaces avoids the formation of microscopic foreign object protrusions, resulting in a smooth, nanoscale rough surface. Specifically, plasma treatment can enhance the consistency of molecular-level contacts, reduce surface energy barriers, and improve the quality of the bonding initiation interface.

[0066] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments that do not specify specific conditions are generally performed according to conventional methods and conditions or according to the product instructions. Unless otherwise specified, the reagents are commercially available; and the performance of products from different sources does not have a significant impact.

[0067] Example 1

[0068] This embodiment of a laser-assisted hybrid bonding interconnect method includes the following steps:

[0069] S1. Chemical mechanical polishing is used to treat the bonding surface of the wafer so that the height difference between the dielectric layer and the metal interconnect is less than 5nm.

[0070] S2. The organic contaminants on the bonding surface of the wafer are removed and the surface activity is enhanced by plasma activation. Then, the wafer is chemically cleaned to remove the oxide layer on the bonding surface.

[0071] S3. Align and bond the bonding surfaces of the two wafers: Use hybrid bonding alignment technology, bond them in a vacuum or inert atmosphere, and ensure appropriate bonding pressure and alignment accuracy to avoid contamination and bubble generation.

[0072] S4. Cover the wafer with a first mask and irradiate the silicon dioxide dielectric layer with an infrared laser with a wavelength of approximately 980nm. The spot size is 10μm, the power is 2W, the pulse time is 100ms, and the dwell time is 300ms. The temperature of the dielectric layer is monitored by a miniature thermocouple and is ≤100℃.

[0073] S5. A second mask is applied to the wafer. The laser emits infrared and blue lasers through an optical module with nonlinear frequency conversion. The blue laser with a wavelength of approximately 370nm heats the copper interconnects. The spot size is 1μm, the power is 10W, the pulse time is 1ms, and the dwell time is 100ms. The temperature of the area where the metal interconnects are located is monitored by a miniature thermocouple and is ≤270℃.

[0074] The wafer assembly obtained by the laser-assisted hybrid bonding interconnect method in this embodiment has a smooth appearance without cracks and good electrical connection.

[0075] Example 2

[0076] This embodiment of a laser-assisted hybrid bonding interconnect method includes the following steps:

[0077] S1. Chemical mechanical polishing is used to treat the bonding surface of the wafer so that the height difference between the dielectric layer and the metal interconnect is less than 5nm.

[0078] S2. The organic contaminants on the bonding surface of the wafer are removed and the surface activity is enhanced by plasma activation. Then, the wafer is chemically cleaned to remove the oxide layer on the bonding surface.

[0079] S3. Align and bond the bonding surfaces of the two wafers: Use hybrid bonding alignment technology, bond them in a vacuum or inert atmosphere, and ensure appropriate bonding pressure and alignment accuracy to avoid contamination and bubble generation.

[0080] S4. Cover the wafer with a first mask and irradiate the silicon dioxide dielectric layer with an infrared laser with a wavelength of approximately 980nm. The spot size is 50μm, the power is 10W, the pulse time is 500ms, and the dwell time is 100ms. The temperature of the dielectric layer is monitored by a miniature thermocouple and is ≤100℃.

[0081] S5. A second mask is applied to the wafer. The laser emits infrared and blue lasers through an optical module with nonlinear frequency conversion. The blue laser with a wavelength of approximately 370nm heats the copper interconnects. The spot size is 10μm, the power is 30W, the pulse time is 100ms, and the dwell time is 50ms. The temperature of the area where the metal interconnects are located is monitored by a miniature thermocouple and is ≤270℃.

[0082] The wafer assembly obtained by the laser-assisted hybrid bonding interconnect method in this embodiment has a smooth appearance without cracks and good electrical connection.

[0083] Example 3

[0084] This embodiment of a laser-assisted hybrid bonding interconnect method includes the following steps:

[0085] S1. Chemical mechanical polishing is used to treat the bonding surface of the wafer so that the height difference between the dielectric layer and the metal interconnect is less than 5nm.

[0086] S2. The organic contaminants on the bonding surface of the wafer are removed and the surface activity is enhanced by plasma activation. Then, the wafer is chemically cleaned to remove the oxide layer on the bonding surface.

[0087] S3. Align and bond the bonding surfaces of the two wafers: Use hybrid bonding alignment technology, bond them in a vacuum or inert atmosphere, and ensure appropriate bonding pressure and alignment accuracy to avoid contamination and bubble generation.

[0088] S4. Cover the wafer with a first mask and irradiate the silicon dioxide dielectric layer with an infrared laser with a wavelength of approximately 980nm. The spot size is 50μm, the power is 2W, the pulse time is 100ms, and the dwell time is 100ms. The temperature of the dielectric layer is monitored by a miniature thermocouple and is ≤100℃.

[0089] S5. A second mask is applied to the wafer. The laser emits infrared and blue lasers through an optical module with nonlinear frequency conversion. The blue laser with a wavelength of approximately 370nm heats the copper interconnects. The spot size is 10μm, the power is 30W, the pulse time is 10ms, and the dwell time is 50ms. The temperature of the area where the metal interconnects are located is monitored by a miniature thermocouple and is ≤270℃.

[0090] The wafer assembly obtained by the laser-assisted hybrid bonding interconnect method in this embodiment has a smooth appearance without cracks and good electrical connection.

[0091] Example 4

[0092] This embodiment of a laser-assisted hybrid bonding interconnect method includes the following steps:

[0093] S1. Chemical mechanical polishing is used to treat the bonding surface of the wafer so that the height difference between the dielectric layer and the metal interconnect is less than 5nm.

[0094] S2. The organic contaminants on the bonding surface of the wafer are removed and the surface activity is enhanced by plasma activation. Then, the wafer is chemically cleaned to remove the oxide layer on the bonding surface.

[0095] S3. Align and bond the bonding surfaces of the two wafers: Use hybrid bonding alignment technology, bond them in a vacuum or inert atmosphere, and ensure appropriate bonding pressure and alignment accuracy to avoid contamination and bubble generation.

[0096] S4. Cover the wafer with a first mask and irradiate the silicon dioxide dielectric layer with an infrared laser with a wavelength of approximately 980nm. The spot size is 30μm, the power is 8W, the pulse time is 300ms, and the dwell time is 200ms. The temperature of the dielectric layer is monitored by a miniature thermocouple and is ≤100℃.

[0097] S5. A second mask is applied to the wafer. The laser emits infrared and blue lasers through an optical module with nonlinear frequency conversion. The blue laser with a wavelength of approximately 370nm heats the copper interconnects. The spot size is 5μm, the power is 20W, the pulse time is 60ms, and the dwell time is 50ms. The temperature of the area where the metal interconnects are located is monitored by a miniature thermocouple and is ≤270℃.

[0098] The wafer assembly obtained by the laser-assisted hybrid bonding interconnect method in this embodiment has a smooth appearance without cracks and good electrical connection.

[0099] Example 5

[0100] This embodiment of a laser-assisted hybrid bonding interconnect method includes the following steps:

[0101] S1. Chemical mechanical polishing is used to treat the bonding surface of the wafer so that the height difference between the dielectric layer and the metal interconnect is less than 5nm.

[0102] S2. The organic contaminants on the bonding surface of the wafer are removed and the surface activity is enhanced by plasma activation. Then, the wafer is chemically cleaned to remove the oxide layer on the bonding surface.

[0103] S3. Align and bond the bonding surfaces of the two wafers: Use hybrid bonding alignment technology, bond them in a vacuum or inert atmosphere, and ensure appropriate bonding pressure and alignment accuracy to avoid contamination and bubble generation.

[0104] S4. Cover the wafer with a first mask and irradiate the silicon dioxide dielectric layer with an infrared laser with a wavelength of approximately 980nm. The spot size is 40μm, the power is 7W, the pulse time is 200ms, and the dwell time is 200ms. The temperature of the dielectric layer is monitored by a miniature thermocouple and is ≤100℃.

[0105] S5. A second mask is applied to the wafer. The laser emits infrared and blue lasers through an optical module with nonlinear frequency conversion. The blue laser with a wavelength of approximately 370nm heats the copper interconnects. The spot size is 8μm, the power is 20W, the pulse time is 40ms, and the dwell time is 60ms. The temperature of the area where the metal interconnects are located is monitored by a miniature thermocouple and is ≤270℃.

[0106] The wafer assembly obtained by the laser-assisted hybrid bonding interconnect method in this embodiment has a smooth appearance without cracks and good electrical connection.

[0107] Other configurations and operations of the laser-assisted hybrid bonding interconnect method according to embodiments of the present invention are known to those skilled in the art and will not be described in detail here. When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. The described performance can be achieved within the range of proportions specified in the present invention. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by those skilled in the art to which this invention pertains.

[0108] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A laser-assisted hybrid bonding interconnection method, characterized in that, Includes the following steps: S1. Process the wafer surface to make the bonding surface of the wafer flat; S2. Clean the bonding surfaces of the wafer to remove organic contaminants and oxide layers; S3. Align and bond the bonding surfaces of the two wafers; then, S4. The bonding surfaces include a dielectric layer and metal interconnects. The dielectric layer is irradiated with an infrared laser to interconnect the dielectric layers of the two bonding surfaces. S5. Use a blue laser to heat the metal interconnect points and interconnect the metal interconnect points on the two surfaces to be bonded.

2. The laser-assisted hybrid bonding interconnection method according to claim 1, characterized in that, In step S4, the dielectric layer is made of silicon dioxide and is irradiated with an infrared laser with a wavelength of approximately 980 nm. In step S5, the metal interconnect is a copper interconnect, which is heated by a blue laser with a wavelength of approximately 370 nm.

3. The laser-assisted hybrid bonding interconnection method according to claim 1, characterized in that, In step S4, during the process of irradiating the dielectric layer with infrared laser, the temperature of the dielectric layer is monitored and kept ≤100℃. In step S5, during the process of heating the metal interconnects with a blue laser, the temperature of the metal interconnects is monitored to keep the temperature of the area where the metal interconnects are located ≤270℃.

4. The laser-assisted hybrid bonding interconnection method according to claim 3, characterized in that, In steps 4 and 5, the temperature of the dielectric layer and the metal interconnect points is obtained using multiple temporarily attached miniature thermocouples. The spacing between two adjacent micro thermocouples is 5-10 μm, and the temperature feedback response time of the micro thermocouple is ≤10 ms.

5. The laser-assisted hybrid bonding interconnection method according to claim 2, characterized in that, In step 4, the infrared laser spot size is 10-50μm, the power is 2-10W, and the pulse time is 100-500ms; In step 5, the size of the blue laser spot is 1-10μm, the power is 10-30W, and the pulse time is 10-100ms.

6. The laser-assisted hybrid bonding interconnection method according to claim 5, characterized in that, In step 4, the dwell time of the infrared laser irradiation medium layer is 100–300 ms; In step 5, the dwell time of the blue laser irradiating the metal interconnect is 50-100ms.

7. The laser-assisted hybrid bonding interconnection method according to claim 1, characterized in that, In step 4, after the wafer is covered with the first mask, the dielectric layer is irradiated with an infrared laser to interconnect the dielectric layers of the two surfaces to be bonded, and then the first mask is removed. In step 5, after the wafer is covered with the second mask, the metal interconnect points are heated by a blue laser, and the metal interconnect points of the two surfaces to be bonded are interconnected before the second mask is removed.

8. The laser-assisted hybrid bonding interconnection method according to claim 1, characterized in that, In steps S4 and S5, the same laser generator is used to perform laser interconnection on the dielectric layer and the metal interconnect points. The laser emits infrared laser and blue laser through an optical module with nonlinear frequency conversion.

9. The laser-assisted hybrid bonding interconnection method according to claim 1, characterized in that, In step S1, chemical mechanical polishing is used to process the bonding surface of the wafer so that the height difference between the dielectric layer and the metal interconnect is less than 5nm.

10. The laser-assisted hybrid bonding interconnection method according to claim 1, characterized in that, In step S2, plasma activation is used to remove organic contaminants from the bonding surfaces of the wafer and enhance surface activity. Then, the wafer is chemically cleaned to remove the oxide layer from the bonding surfaces.

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