Wafer bonding device and bonding method

Abstract

The invention provides a wafer bonding device and a wafer bonding method, and belongs to the technical field of photoelectron manufacturing. The bonding device comprises two pressing plates and buffer pads, wherein the buffer pads are arranged on two opposite plate surfaces of the two pressing plates. The problem of non-uniform pressure in the bonding process can be improved, and the yield of the subsequent process is improved.

Description

Technical Field

[0001] This disclosure relates to the field of optoelectronic manufacturing technology, and in particular to a wafer bonding apparatus and bonding method. Background Technology

[0002] In the fabrication process of Micro LED chips, the wafer to be bonded is often bonded and fixed onto a sapphire substrate, and then the temporary substrate on the wafer to be bonded is peeled off, so that the Micro LED chips on the wafer are transferred to the sapphire substrate.

[0003] In related technologies, the bonding apparatus includes two bonding plates, with the wafer to be bonded and the sapphire substrate placed on opposite surfaces of the two bonding plates. During the bonding process, a bonding adhesive layer is coated on the surface of the sapphire substrate. Then, the two bonding plates are brought closer together, and pressure and heat are applied to bond the sapphire substrate with the bonding adhesive layer to the wafer to be bonded.

[0004] Because the surfaces of the laminating plate, sapphire substrate, wafer to be bonded, and bonding adhesive layer are all uneven and rough, this can lead to uneven pressure distribution during the bonding process. This uneven pressure results in variations in the thickness of the bonding adhesive layer in different areas after bonding, which in turn adversely affects subsequent processes. Summary of the Invention

[0005] This disclosure provides a wafer bonding apparatus and bonding method that can improve the problem of uneven pressure during the bonding process and increase the yield of subsequent processes. The technical solution is as follows: This disclosure provides a wafer bonding apparatus, which includes two bonding plates and a buffer pad, wherein the buffer pad is provided on each of the two opposite surfaces of the two bonding plates.

[0006] In another implementation of the present disclosure, the cushioning pad includes at least one of aluminum foil, copper foil, Teflon layer, graphite layer and silicone layer.

[0007] In another implementation of the embodiments of this disclosure, the thickness of the buffer pad is 0.1 mm to 2 mm.

[0008] In another implementation of the embodiments of this disclosure, one of the two pressing plates is used to fix the wafer to be bonded, and the other of the two pressing plates is used to fix the substrate. The wafer to be bonded is located on the buffer pad of the corresponding pressing plate, and the substrate is located on the buffer pad of the corresponding pressing plate. The orthographic projection of the wafer to be bonded on the plate surface of the corresponding pressing plate is located within the orthographic projection of the corresponding buffer pad on the plate surface of the pressing plate. The orthographic projection of the substrate on the plate surface of the corresponding pressing plate is located within the orthographic projection of the corresponding buffer pad on the plate surface of the pressing plate.

[0009] This disclosure provides a wafer bonding method, the bonding method comprising: setting buffer pads on two opposite surfaces of two bonding plates; placing a wafer to be bonded and a substrate on the two buffer pads respectively; and controlling the two bonding plates to adhere together so that the wafer to be bonded is bonded to the substrate.

[0010] In another implementation of the present disclosure, the cushioning pad includes at least one of aluminum foil, copper foil, Teflon layer, graphite layer and silicone layer.

[0011] In another implementation of the present disclosure, providing buffer pads on two opposite surfaces of the two pressing plates includes: determining the thickness of the buffer pads based on the bonding pressure applied by the two pressing plates, wherein the thickness of the buffer pads is positively correlated with the bonding pressure.

[0012] In another implementation of this disclosure, the buffer pad is an aluminum foil; when the bonding pressure is less than or equal to 1000 kg, the thickness of the buffer pad is 0.1 mm to 2 mm; when the bonding pressure is 1000 kg to 2000 kg, the thickness of the buffer pad is 0.5 mm to 2 mm; and when the bonding pressure is 2000 kg to 3000 kg, the thickness of the buffer pad is 1 mm to 2 mm.

[0013] In another implementation of this disclosure, the buffer pad is a Teflon layer; when the bonding pressure is less than or equal to 1000 kg, the thickness of the buffer pad is 0.5 mm to 2 mm; when the bonding pressure is 1000 kg to 3000 kg, the thickness of the buffer pad is 2 mm.

[0014] In another implementation of the present disclosure, the provision of buffer pads on opposite surfaces of the two pressing plates further includes: determining the material of the buffer pads based on the bonding temperature; when the bonding temperature is greater than or equal to 150°C, using one of graphite layer, aluminum foil, and copper foil as the buffer pads; when the bonding temperature is less than 150°C, using one of silicone layer and Teflon layer as the buffer pads.

[0015] The beneficial effects of the technical solutions provided in this disclosure include at least the following: The wafer bonding apparatus provided in this disclosure adds buffer pads to the opposing surfaces of two bonding plates. The deformability of the buffer pads adaptively fills the microscopic unevenness of the surfaces of the bonding plates, the wafer to be bonded, and the substrate. Through flexible contact, the originally concentrated local high pressure is dispersed into a more uniform overall pressure. In high-pressure areas, the buffer pads reduce local stress peaks with greater compression, while in low-pressure areas, the buffer pads compensate for insufficient contact with smaller compression, ultimately achieving a globally uniform pressure distribution during the bonding process. Furthermore, the better surface flatness of the buffer pads reduces the interference of the original material surface roughness on pressure transmission, ensuring a more stable pressure transmission path from the bonding plates to the bonding adhesive layer.

[0016] This embodiment of the invention directly avoids the risk of die cracking and poor bonding caused by uneven pressure by setting a buffer pad, while ensuring the uniformity of the bonding adhesive layer thickness. This provides a stable structural foundation for subsequent thinning, laser cutting or chip packaging processes, and can effectively improve product yield and long-term reliability. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this disclosure, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of a wafer bonding device provided in an embodiment of this disclosure; Figure 2 This is a bonding state diagram of a bonding device provided in an embodiment of this disclosure; Figure 3 This is a flowchart of a wafer bonding method provided in an embodiment of this disclosure.

[0019] The markings in the diagram are explained as follows: 10. Pressed plate; 20. Cushioning pad; 30. Wafers to be bonded; 40. Substrate; 50. Bonding adhesive layer. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this disclosure clearer, the embodiments of this disclosure will be described in further detail below with reference to the accompanying drawings.

[0021] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” “third,” and similar terms used in this patent application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an” or “a” and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “comprising” or “including” and similar terms mean that the elements or objects preceding “comprising” or “including” encompass the elements or objects listed following “comprising” or “including” and their equivalents, and do not exclude other elements or objects. The terms “connected” or “linked” and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms “upper,” “lower,” “left,” “right,” “top,” and “bottom,” etc., are used only to indicate relative positional relationships, and these relative positional relationships may change accordingly when the absolute position of the described objects changes.

[0022] Figure 1 This is a schematic diagram of the structure of a wafer bonding apparatus provided in an embodiment of this disclosure. Figure 1 As shown, the bonding device includes two pressing plates 10 and a buffer pad 20, with the buffer pad 20 provided on each of the two opposite surfaces of the two pressing plates 10.

[0023] For example, the surface roughness Ra of the buffer pad 20 is ≤0.8μm. The surface smoothness of the buffer pad 20 is good at this roughness.

[0024] The wafer bonding apparatus provided in this embodiment adds buffer pads 20 to the opposing surfaces of the two bonding plates 10. The deformability of the buffer pads 20 adaptively fills the microscopic unevenness of the surfaces of the bonding plates 10, the wafer 30 to be bonded, and the substrate 40, dispersing the originally concentrated local high pressure into a more uniform overall pressure through flexible contact. In high-pressure areas, the buffer pads 20 reduce local stress peaks through greater compression, while in low-pressure areas, they compensate for insufficient contact with smaller compression, ultimately achieving a globally uniform pressure distribution during the bonding process. Furthermore, the good surface flatness of the buffer pads 20 reduces the interference of the original material surface roughness on pressure transmission, ensuring a more stable pressure transmission path from the bonding plates 10 to the bonding adhesive layer.

[0025] This embodiment of the disclosure directly avoids the risk of die cracking and poor bonding caused by uneven pressure by setting a buffer pad 20, while ensuring the uniformity of the bonding adhesive layer thickness. This provides a stable structural foundation for subsequent thinning processes, laser cutting processes, or chip packaging processes, and can effectively improve the product yield and long-term reliability.

[0026] Optionally, the cushioning pad 20 includes at least one of aluminum foil, copper foil, Teflon layer, graphite layer and silicone layer.

[0027] For example, the buffer pad is aluminum foil. Aluminum foil has good ductility and can deform appropriately with changes in pressure distribution during the bonding process, thereby alleviating the problem of uneven pressure to a certain extent and allowing the pressure to be transmitted more evenly to the bonding site.

[0028] Secondly, aluminum foil has excellent thermal conductivity, which can quickly conduct away the heat generated during the bonding process, helping to ensure the uniformity of the bonding temperature and avoid local overheating that could damage the wafer and sapphire substrate 40.

[0029] For example, the buffer pad is copper foil. Copper has good flexibility and can adapt to the slight unevenness of the surfaces of the laminating plate 10 and the bonded parts. It disperses the pressure through its own deformation, so that the pressure is evenly distributed and reduces problems such as grain cracking and poor bonding caused by pressure concentration.

[0030] Furthermore, copper has strong corrosion resistance and can maintain its own performance stability in the bonding environment. It is not easy for its performance to change due to external factors, thus ensuring the durability of the buffering effect.

[0031] For example, the cushioning pad is a Teflon layer. Teflon has extremely low surface energy and a very smooth surface, which can effectively reduce friction between adjacent components, avoid additional stress caused by uneven friction during bonding, and further ensure the uniformity of pressure distribution.

[0032] Furthermore, Teflon possesses excellent chemical stability, resisting various chemicals that may come into contact with during the bonding process, preventing corrosion or chemical reactions, thus ensuring the stable performance of the cushioning pad. In addition, Teflon also exhibits good high-temperature resistance, operating normally in the high-temperature environments required for bonding without softening or deforming due to temperature increases, ensuring continuous cushioning throughout the bonding process and improving the reliability of the bonding quality.

[0033] For example, the buffer pad is a graphite layer. Graphite has good lubrication properties, which can reduce the coefficient of friction between the pressing plate 10 and the bonded parts, reduce the influence of friction on the pressure distribution, make the pressure act more evenly on the bonding interface, and reduce the risk of grain damage and poor bonding.

[0034] Furthermore, graphite has high thermal conductivity, which allows it to quickly dissipate the heat generated during bonding, helping to maintain the uniformity of the bonding temperature and preventing damage to the material from excessively high local temperatures. At the same time, graphite has a certain degree of elasticity and flexibility, allowing it to adapt to surface unevenness and buffer pressure through its own deformation, thus improving the stability and reliability of the bonding.

[0035] For example, the buffer pad is a silicone layer. Silicone has excellent elasticity and can adaptively deform according to the magnitude and distribution of pressure during the bonding process, effectively dispersing the pressure and ensuring that the pressure is evenly transmitted to the bonding site, greatly reducing the negative impact of uneven pressure.

[0036] Furthermore, silicone has good temperature resistance and can maintain stable physical properties over a wide temperature range. It can adapt to the high-temperature environment during the bonding process and will not age or deform rapidly due to temperature changes, thus ensuring the durability of the cushioning effect.

[0037] Optionally, the specific material used to make the buffer pad 20 can be determined based on the bonding temperature.

[0038] For example, when the bonding temperature is greater than or equal to 150°C, one of the following is used as the buffer pad 20: graphite layer, aluminum foil, and copper foil.

[0039] In high-temperature environments where the bonding temperature exceeds 150°C, graphite layers, aluminum foil, and copper foil can be used as buffer pads 20.

[0040] Among them, the graphite layer can withstand temperatures up to several thousand degrees Celsius, has a stable structure at high temperatures, conducts heat quickly, and can evenly distribute pressure; the aluminum foil and copper foil have high melting points and do not deform or soften at 150°C, maintaining buffering performance. At the same time, the thermal conductivity of aluminum / copper can help balance the bonding temperature field, avoid local overheating, and ensure a stable and reliable high-temperature bonding process.

[0041] For example, when the bonding temperature is less than 150°C, one of the silicone layer and the Teflon layer is used as the buffer pad 20.

[0042] In low-temperature conditions where the bonding temperature is below 150°C, a silicone layer and a Teflon layer can be used as a buffer pad 20.

[0043] The silicone layer maintains high elasticity and flexibility below 150℃, can uniformly disperse pressure through deformation, and has stable chemical properties, low cost, and is easy to process; the Teflon layer has a smooth surface and low coefficient of friction, and does not soften or chemically degrade below 150℃, which can reduce frictional interference and uniformly transmit pressure. Both can meet the requirements of low-temperature bonding for buffer protection and process stability.

[0044] Optionally, the cushioning pad 20 may include multiple layers of laminated membranes.

[0045] For example, the material film layer (such as a Teflon layer) with a smooth surface and certain lubricity is used closest to the pressing plate 10, which can reduce the friction between the buffer pad 20 and the pressing plate 10 during the bonding process and avoid abnormal pressure distribution due to uneven friction.

[0046] For example, the intermediate layer is a material film layer with a moderate elastic modulus (such as a silicone layer), which mainly plays the role of uniformly dispersing pressure and can adapt to the surface undulations of the bonded parts.

[0047] For example, the bottom layer uses a material with a certain degree of hardness and support (such as aluminum foil) to provide stable support for the entire buffer pad 20, preventing the buffer pad 20 from sinking or deforming excessively under pressure, and ensuring the stability of the overall structure of the buffer pad 20.

[0048] Optionally, the buffer pad 20 may include multiple layers of laminated film, and the elastic modulus of each film layer gradually increases from the side in contact with the bonded part to the side in contact with the pressing plate 10.

[0049] In this way, during the bonding process, the film layer in contact with the bonded part can first provide fine buffering and pressure dispersion for the minor unevenness of the surface, while the film layer in contact with the pressing plate 10 provides more stable overall support, so that the pressure can be transmitted more evenly and stably to the entire bonding interface.

[0050] Optionally, the thickness of the cushioning pad 20 is 0.1 mm to 2 mm.

[0051] The thinner buffer pad 20 can more precisely conform to the surface of the bonding plate 10 and the component being bonded, effectively sensing and buffering even minute surface undulations. Furthermore, it can quickly disperse pressure in localized high-pressure areas, allowing pressure to be transmitted more evenly to the bonding interface, preventing damage to the wafer or other components due to pressure concentration, while ensuring balanced stress across the bonding adhesive layer and improving bonding quality.

[0052] If the buffer pad 20 is too thick, it may cause delays and instability in pressure transmission, affecting the accuracy and efficiency of bonding. A thickness of 0.1mm to 2mm provides sufficient buffering performance without excessively increasing cost and operational complexity, and can also adapt to the needs of different bonding processes.

[0053] In this embodiment of the disclosure, the thickness of the buffer pad is positively correlated with the bonding pressure.

[0054] For example, when the buffer pad 20 is aluminum foil, the thickness of the buffer pad 20 is 0.1 mm to 2 mm when the bonding pressure is less than or equal to 1000 kg.

[0055] When the bonding pressure is less than or equal to 1000 kg, the bonding pressure is relatively low. At this time, the aluminum foil can be designed to be as thin as 0.1 mm. This thickness of aluminum foil can accurately fit the slight undulations of the surface, quickly respond to local high pressure, and disperse stress through high elastic deformation to avoid grain cracking. The upper limit of the thickness is 2 mm, which ensures uniform pressure transmission without excessively increasing the assembly complexity, adapts to the requirements of light-load bonding, and steadily improves the bonding quality.

[0056] For example, when the buffer pad 20 is aluminum foil, the thickness of the buffer pad 20 is 0.5 mm to 2 mm when the bonding pressure is 1000 kg to 2000 kg.

[0057] When the bonding pressure is between 1000 kg and 2000 kg, the bonding pressure is moderate. At this point, the aluminum foil can be designed to be as thin as 0.5 mm to ensure that the aluminum foil still has sufficient elastic deformation capacity, effectively buffering the medium load pressure and avoiding local stress concentration caused by excessive thinness. The upper limit of 2 mm maintains buffering stability, taking into account both pressure distribution and structural durability. This range balances the adhesion and deformation resistance requirements under medium to high pressure, ensuring uniform bonding adhesive layer thickness and improving bonding reliability.

[0058] For example, when the buffer pad 20 is aluminum foil, the thickness of the buffer pad 20 is 1 mm to 2 mm when the bonding pressure is 2000 kg to 3000 kg.

[0059] When the bonding pressure is between 2000 kg and 3000 kg, the bonding pressure is relatively high, and a thicker aluminum foil is required in the high-pressure range. Therefore, the aluminum foil is designed to be as thin as 1 mm to ensure that the aluminum foil has sufficient rigid support and deformation space, to avoid crushing failure due to excessive thinness, and to ensure that stress can still be effectively distributed under high pressure; the upper limit of 2 mm provides redundant buffering capacity to cope with pressure fluctuations and maintain the stability of interface contact.

[0060] For example, when the buffer pad 20 is a Teflon layer, the thickness of the buffer pad 20 is 0.5 mm to 2 mm when the bonding pressure is less than or equal to 1000 kg.

[0061] When the bonding pressure is less than or equal to 1000 kg, the bonding pressure is relatively low, and the thickness of the Teflon layer can be designed to be as thin as 0.5 mm. The low friction properties of Teflon can precisely adapt to the slight undulations of the surface, reduce frictional interference during the bonding process, and evenly distribute low-pressure stress. The maximum thickness of 2 mm enhances the deformation redundancy of the buffer pad, adapts to slight surface unevenness, and at the same time utilizes its chemical stability to prevent the corrosive effects of the bonding environment, ensuring stable interface adhesion during low-pressure bonding.

[0062] For example, when the buffer pad 20 is a Teflon layer, the thickness of the buffer pad 20 is 2 mm when the bonding pressure is 1000 kg to 3000 kg.

[0063] When the bonding pressure is between 1000 kg and 3000 kg, the bonding pressure is relatively high, and the thickness of the fixed buffer pad 20 is 2 mm. The 2 mm Teflon layer provides stable deformation buffering capacity, and its high lubricity can reduce frictional stress concentration under high pressure and avoid local wear; at the same time, Teflon's excellent temperature resistance and chemical stability maintain stable performance in high-pressure and high-temperature environments, preventing material deformation or chemical reactions from affecting the bonding quality.

[0064] Figure 2 This is a bonding state diagram of a bonding device provided in an embodiment of this disclosure. Figure 2 As shown, one of the two pressing plates 10 is used to fix the wafer 30 to be bonded, and the other of the two pressing plates 10 is used to fix the substrate 40. The wafer 30 to be bonded is located on the buffer pad 20 of the corresponding pressing plate 10, and the substrate 40 is located on the buffer pad 20 of the corresponding pressing plate 10.

[0065] like Figure 2 As shown, the orthographic projection of the wafer 30 to be bonded onto the surface of the corresponding laminating plate 10 lies within the orthographic projection of the corresponding buffer pad 20 onto the surface of the laminating plate 10.

[0066] like Figure 2 As shown, the orthographic projection of the substrate 40 on the surface of the corresponding pressing plate 10 lies within the orthographic projection of the corresponding buffer pad 20 on the surface of the pressing plate 10.

[0067] In the above implementation, the orthographic projections of the wafer 30 and the substrate 40 to be bonded are both located within the orthographic projection of the corresponding buffer pad 20, ensuring that the pressure is precisely applied to the target area during the bonding process. The buffer pad 20 completely covers the wafer and the substrate 40, allowing the pressure to be uniformly transmitted to the entire bonding interface through the buffer pad 20, avoiding the problems of edge stress concentration or insufficient local pressure, thereby ensuring a uniform bonding adhesive layer thickness.

[0068] Meanwhile, since the wafer 30 to be bonded and the substrate 40 are completely placed on the buffer pad 20, the buffer pad 20 can fully utilize its deformation characteristics to adaptively compensate for the microscopic unevenness of the wafer, substrate 40 and laminating plate 10 surfaces, further optimizing the uniformity of pressure distribution. Especially for fragile materials such as wafers, the complete coverage of the buffer pad 20 provides all-round protection, reducing the risk of dark cracks or breakage of the grains during the bonding process.

[0069] Optionally, an annular groove can be provided on the surface of the buffer pad 20 that contacts the wafer 30 to be bonded and the substrate 40, and the annular groove corresponds to the peripheral edge of the wafer 30 to be bonded or the peripheral edge of the substrate 40.

[0070] When pressure is applied during the bonding process, stress concentration is more likely to occur at the edges of the wafer 30 and substrate 40 to be bonded. The annular groove can disperse the edge pressure and avoid excessive stress concentration that could cause damage to the edges of the wafer or substrate 40, such as dark cracks or edge chipping.

[0071] For example, the pressing plate 10 can be a silicon carbide plate. Silicon carbide has high hardness and rigidity, which can maintain the shape stability of the pressing plate 10, ensure accurate pressure transmission during the bonding process, and avoid uneven pressure distribution due to plate surface deformation. Its high thermal conductivity can quickly and evenly conduct the heat generated by bonding, ensuring the uniformity of bonding temperature.

[0072] Figure 3 This is a flowchart of a wafer bonding method provided in an embodiment of this disclosure. Figure 3 As shown, the bonding method includes: Step S11: Set buffer pads 20 on the two opposite surfaces of the two pressing plates 10 respectively.

[0073] For example, the surface roughness Ra of the buffer pad 20 is ≤0.8μm.

[0074] For example, the laminating plate 10 may be a silicon carbide plate.

[0075] Step S12: Place the wafer 30 to be bonded and the substrate 40 on the two buffer pads 20 respectively.

[0076] For example, the wafer to be bonded 30 may include a substrate and a plurality of light-emitting units located on the substrate.

[0077] For example, the substrate 40 may be a sapphire substrate 40.

[0078] Step S13: Control the two pressing plates 10 to bond together so that the wafer 30 to be bonded is bonded to the substrate 40.

[0079] The wafer bonding method provided in this disclosure adds buffer pads 20 to the opposing surfaces of two bonding plates 10. The deformability of the buffer pads 20 adaptively fills the microscopic unevenness of the surfaces of the bonding plates 10, the wafer 30 to be bonded, and the substrate 40, dispersing the originally concentrated local high pressure into a more uniform overall pressure through flexible contact. In high-pressure areas, the buffer pads 20 reduce local stress peaks through greater compression, while in low-pressure areas, they compensate for insufficient contact with smaller compression, ultimately achieving a globally uniform pressure distribution during bonding. Furthermore, the good surface flatness of the buffer pads 20 reduces the interference of the original material surface roughness on pressure transmission, ensuring a more stable pressure transmission path from the bonding plates 10 to the bonding adhesive layer.

[0080] This embodiment of the disclosure directly avoids the risk of die cracking and poor bonding caused by uneven pressure by setting a buffer pad 20, while ensuring the uniformity of the bonding adhesive layer thickness. This provides a stable structural foundation for subsequent thinning processes, laser cutting processes, or chip packaging processes, and can effectively improve the product yield and long-term reliability.

[0081] Optionally, each light-emitting unit in the wafer 30 to be bonded may include a first semiconductor layer, a multi-quantum well layer, and a second semiconductor layer stacked sequentially.

[0082] In this embodiment of the present disclosure, one of the first semiconductor layer and the second semiconductor layer is an n-type layer, and the other of the first semiconductor layer and the second semiconductor layer is a p-type layer.

[0083] For example, the first semiconductor layer is an n-type layer and the second semiconductor layer is a p-type layer.

[0084] Taking a red-light epitaxial structure as an example, the structure of each layer is illustrated. In the red-light epitaxial structure, the p-type layer includes a p-type AlInP layer. The thickness of the p-type AlInP layer can be from 0.5 μm to 3 μm.

[0085] The multiple quantum well layer can include alternating AlGaInP quantum well layers and AlGaInP quantum barrier layers. Specifically, the multiple quantum well layer can include 3 to 8 alternating stacked AlGaInP quantum well layers and AlGaInP quantum barrier layers, with different Al contents in the AlGaInP quantum well layers and AlGaInP quantum barrier layers.

[0086] The n-type layer includes an n-type AlGaInP layer. The thickness of the n-type AlGaInP layer can be from 0.5 μm to 3 μm.

[0087] Optionally, the thickness of the light-emitting unit is 2 μm to 10 μm.

[0088] Optionally, the cushioning pad 20 includes at least one of aluminum foil, copper foil, Teflon layer, graphite layer and silicone layer.

[0089] For example, the buffer pad is aluminum foil. Aluminum foil has good ductility and can deform appropriately with changes in pressure distribution during the bonding process, thereby alleviating the problem of uneven pressure to a certain extent and allowing the pressure to be transmitted more evenly to the bonding site.

[0090] For example, the buffer pad is copper foil. Copper has good flexibility and can adapt to the slight unevenness of the surfaces of the laminating plate 10 and the bonded parts. It disperses the pressure through its own deformation, so that the pressure is evenly distributed and reduces problems such as grain cracking and poor bonding caused by pressure concentration.

[0091] For example, the cushioning pad is a Teflon layer. Teflon has extremely low surface energy and a very smooth surface, which can effectively reduce friction between adjacent components, avoid additional stress caused by uneven friction during bonding, and further ensure the uniformity of pressure distribution.

[0092] For example, the buffer pad is a graphite layer. Graphite has good lubrication properties, which can reduce the coefficient of friction between the pressing plate 10 and the bonded parts, reduce the influence of friction on the pressure distribution, make the pressure act more evenly on the bonding interface, and reduce the risk of grain damage and poor bonding.

[0093] For example, the buffer pad is a silicone layer. Silicone has excellent elasticity and can adaptively deform according to the magnitude and distribution of pressure during the bonding process, effectively dispersing the pressure and ensuring that the pressure is evenly transmitted to the bonding site, greatly reducing the negative impact of uneven pressure.

[0094] When setting the buffer pad 20 in step S11, the thickness of the buffer pad can be determined based on the bonding pressure applied by the two pressing plates 10.

[0095] The thickness of the buffer pad is positively correlated with the bonding pressure.

[0096] Optionally, the thickness of the cushioning pad 20 is 0.1 mm to 2 mm.

[0097] For example, when the buffer pad 20 is aluminum foil, the thickness of the buffer pad 20 is 0.1 mm to 2 mm when the bonding pressure is less than or equal to 1000 kg.

[0098] When the bonding pressure is less than or equal to 1000 kg, the bonding pressure is relatively low. At this time, the aluminum foil can be designed to be as thin as 0.1 mm. This thickness of aluminum foil can accurately fit the slight undulations of the surface, quickly respond to local high pressure, and disperse stress through high elastic deformation to avoid grain cracking. The upper limit of the thickness is 2 mm, which ensures uniform pressure transmission without excessively increasing the assembly complexity, adapts to the requirements of light-load bonding, and steadily improves the bonding quality.

[0099] For example, when the buffer pad 20 is aluminum foil, the thickness of the buffer pad 20 is 0.5 mm to 2 mm when the bonding pressure is 1000 kg to 2000 kg.

[0100] When the bonding pressure is between 1000 kg and 2000 kg, the bonding pressure is moderate. At this point, the aluminum foil can be designed to be as thin as 0.5 mm to ensure that the aluminum foil still has sufficient elastic deformation capacity, effectively buffering the medium load pressure and avoiding local stress concentration caused by excessive thinness. The upper limit of 2 mm maintains buffering stability, taking into account both pressure distribution and structural durability. This range balances the adhesion and deformation resistance requirements under medium to high pressure, ensuring uniform bonding adhesive layer thickness and improving bonding reliability.

[0101] For example, when the buffer pad 20 is aluminum foil, the thickness of the buffer pad 20 is 1 mm to 2 mm when the bonding pressure is 2000 kg to 3000 kg.

[0102] When the bonding pressure is between 2000 kg and 3000 kg, the bonding pressure is relatively high, and a thicker aluminum foil is required in the high-pressure range. Therefore, the aluminum foil is designed to be as thin as 1 mm to ensure that the aluminum foil has sufficient rigid support and deformation space, to avoid crushing failure due to excessive thinness, and to ensure that stress can still be effectively distributed under high pressure; the upper limit of 2 mm provides redundant buffering capacity to cope with pressure fluctuations and maintain the stability of interface contact.

[0103] For example, when the buffer pad 20 is a Teflon layer, the thickness of the buffer pad 20 is 0.5 mm to 2 mm when the bonding pressure is less than or equal to 1000 kg.

[0104] When the bonding pressure is less than or equal to 1000 kg, the bonding pressure is relatively low, and the thickness of the Teflon layer can be designed to be as thin as 0.5 mm. The low friction properties of Teflon can precisely adapt to the slight undulations of the surface, reduce frictional interference during the bonding process, and evenly distribute low-pressure stress. The maximum thickness of 2 mm enhances the deformation redundancy of the buffer pad, adapts to slight surface unevenness, and at the same time utilizes its chemical stability to prevent the corrosive effects of the bonding environment, ensuring stable interface adhesion during low-pressure bonding.

[0105] For example, when the buffer pad 20 is a Teflon layer, the thickness of the buffer pad 20 is 2 mm when the bonding pressure is 1000 kg to 3000 kg.

[0106] When the bonding pressure is between 1000 kg and 3000 kg, the bonding pressure is relatively high, and the thickness of the fixed buffer pad 20 is 2 mm. The 2 mm Teflon layer provides stable deformation buffering capacity, and its high lubricity can reduce frictional stress concentration under high pressure and avoid local wear; at the same time, Teflon's excellent temperature resistance and chemical stability maintain stable performance in high-pressure and high-temperature environments, preventing material deformation or chemical reactions from affecting the bonding quality.

[0107] When setting the buffer pad 20 in step S11, the material of the buffer pad 20 can be determined according to the bonding temperature.

[0108] For example, when the bonding temperature is greater than or equal to 150°C, one of the following is used as the buffer pad 20: graphite layer, aluminum foil, and copper foil.

[0109] In high-temperature environments where the bonding temperature exceeds 150°C, graphite layers, aluminum foil, and copper foil can be used as buffer pads 20.

[0110] Among them, the graphite layer can withstand temperatures up to several thousand degrees Celsius, has a stable structure at high temperatures, conducts heat quickly, and can evenly distribute pressure; the aluminum foil and copper foil have high melting points and do not deform or soften at 150°C, maintaining buffering performance. At the same time, the thermal conductivity of aluminum / copper can help balance the bonding temperature field, avoid local overheating, and ensure a stable and reliable high-temperature bonding process.

[0111] For example, when the bonding temperature is less than 150°C, one of the silicone layer and the Teflon layer is used as the buffer pad 20.

[0112] In low-temperature conditions where the bonding temperature is below 150°C, a silicone layer and a Teflon layer can be used as a buffer pad 20.

[0113] The silicone layer maintains high elasticity and flexibility below 150℃, can uniformly disperse pressure through deformation, and has stable chemical properties, low cost, and is easy to process; the Teflon layer has a smooth surface and low coefficient of friction, and does not soften or chemically degrade below 150℃, which can reduce frictional interference and uniformly transmit pressure. Both can meet the requirements of low-temperature bonding for buffer protection and process stability.

[0114] Step S12, which involves placing the substrate 40 on the buffer pad 20, may include: first coating the substrate 40 with a bonding adhesive layer 50, and then placing the substrate 40 on the buffer pad 20 such that the bonding adhesive layer 50 faces away from the buffer pad 20.

[0115] Step S12, placing the wafer 30 to be bonded on the buffer pad 20, may include: placing the wafer 30 to be bonded on the buffer pad 20 such that the electrodes of the wafer 30 to be bonded face away from the buffer pad 20.

[0116] like Figure 2 As shown, step S13 may include: starting the pressing device and pushing the two pressing plates 10 to move towards each other at a set rate. During the bonding process, a stable and appropriate pressure is applied simultaneously, and the temperature is precisely controlled so that the bonding adhesive layer 50 softens and flows under the combined action of pressure and heat, filling the tiny gap between the wafer 30 to be bonded and the substrate 40, thereby achieving a firm bond between the two.

[0117] The above is not intended to limit this disclosure in any way. Although this disclosure has been disclosed above through embodiments, it is not intended to limit this disclosure. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the technical solution of this disclosure. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of this disclosure without departing from the content of the technical solution of this disclosure shall still fall within the scope of the technical solution of this disclosure.

Claims

1. A wafer bonding apparatus, characterized in that, The bonding device includes two pressing plates (10) and a buffer pad (20), with the buffer pad (20) provided on each of the two opposite surfaces of the two pressing plates (10).

2. The bonding apparatus according to claim 1, characterized in that, The cushioning pad (20) includes at least one of aluminum foil, copper foil, Teflon layer, graphite layer and silicone layer.

3. The bonding apparatus according to claim 1, characterized in that, The thickness of the cushioning pad (20) is 0.1 mm to 2 mm.

4. The bonding apparatus according to any one of claims 1 to 3, characterized in that, One of the two pressing plates (10) is used to fix the wafer (30) to be bonded, and the other of the two pressing plates (10) is used to fix the substrate (40). The wafer (30) to be bonded is located on the buffer pad (20) of the corresponding pressing plate (10), and the substrate (40) is located on the buffer pad (20) of the corresponding pressing plate (10). The orthographic projection of the wafer to be bonded (30) on the corresponding bonding plate (10) is located within the orthographic projection of the corresponding buffer pad (20) on the bonding plate (10); The orthographic projection of the substrate (40) on the corresponding plate surface of the pressing plate (10) lies within the orthographic projection of the corresponding buffer pad (20) on the plate surface of the pressing plate (10).

5. A wafer bonding method, characterized in that, The bonding method includes: Buffer pads (20) are respectively provided on the two opposite surfaces of the two pressing plates (10); The wafer (30) to be bonded and the substrate (40) are placed on the two buffer pads (20), respectively. Control the two pressing plates (10) to bond together so that the wafer to be bonded (30) is bonded to the substrate (40).

6. The bonding method according to claim 5, characterized in that, The cushioning pad (20) includes at least one of aluminum foil, copper foil, Teflon layer, graphite layer and silicone layer.

7. The bonding method according to claim 6, characterized in that, The buffer pads (20) are respectively provided on the two opposite surfaces of the two pressing plates (10), including: The thickness of the buffer pad (20) is determined based on the bonding pressure applied by the two bonding plates (10), and the thickness of the buffer pad (20) is positively correlated with the bonding pressure.

8. The bonding method according to claim 7, characterized in that, The cushioning pad (20) is aluminum foil; When the bonding pressure is less than or equal to 1000 kg, the thickness of the buffer pad (20) is 0.1 mm to 2 mm; When the bonding pressure is 1000 kg to 2000 kg, the thickness of the buffer pad (20) is 0.5 mm to 2 mm; When the bonding pressure is 2000 kg to 3000 kg, the thickness of the buffer pad (20) is 1 mm to 2 mm.

9. The bonding method according to claim 7, characterized in that, The buffer pad (20) is a Teflon layer; When the bonding pressure is less than or equal to 1000 kg, the thickness of the buffer pad (20) is 0.5 mm to 2 mm; When the bonding pressure is 1000kg to 3000kg, the thickness of the buffer pad (20) is 2mm.

10. The bonding method according to claim 6, characterized in that, Providing buffer pads (20) on the two opposite surfaces of the two pressing plates (10) also includes: The material of the buffer pad (20) is determined based on the bonding temperature; When the bonding temperature is greater than or equal to 150°C, one of the following is used as the buffer pad (20): graphite layer, aluminum foil and copper foil. When the bonding temperature is less than 150°C, one of the silicone layer and the Teflon layer is used as a buffer pad (20).

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