A patterned composite substrate based on sponge bumps and a method of fabrication

Abstract

This invention discloses a patterned composite substrate based on sponge protrusions and its fabrication method, comprising: a sapphire substrate; multiple sponge protrusion microstructures located on one side of the sapphire substrate in the thickness direction; the sponge protrusion microstructures include a sponge skeleton structure, which is fabricated using silicon nitride material and has a three-dimensional interpenetrating network of pores inside. This technical solution not only utilizes the conical shape to buffer the lateral stress of epitaxial growth, but also utilizes the three-dimensional interpenetrating network of pores to achieve loose and elastic properties, further providing a template for stress relaxation and defect annihilation during epitaxial growth. This results in a low-stress, low-defect epitaxial material layer, improving crystal quality. Simultaneously, it can increase the LED light reflection probability through refractive index transition, thereby improving light extraction efficiency.

Description

Technical Field

[0001] The embodiments of the present invention relate to LED patterned substrate technology, and more particularly to a patterned composite substrate based on sponge protrusions and its preparation method. Background Technology

[0002] Gallium nitride-based light-emitting diodes (LEDs) are commonly used light-emitting devices in the fields of solid-state lighting and semiconductor displays. Among them, heteroepitaxial technology is the mainstream technology to solve the problem of GaN thin film growth. In particular, the submicron-level protrusion array constructed on the surface of a periodic microstructure sapphire substrate formed by photolithography and dry etching can effectively suppress dislocation density and improve the brightness of the diode chip.

[0003] To overcome the physical limitations of traditional single-material substrates and improve the crystal quality of epitaxial materials, the industry has developed multi-material composite substrate technology. By optimizing the matching of thermal expansion coefficients through a multi-material system, residual stress in the epitaxial layer can be reduced, effectively controlling the photon propagation path and converting lateral guided modes into vertical radiation modes. Composite substrates are developing towards multifunctional integration; however, how to further reduce epitaxial stress to improve GaN crystal quality and increase the photon escape probability remains a key technological bottleneck that the industry urgently needs to overcome. Summary of the Invention

[0004] This invention provides a patterned composite substrate based on sponge protrusions and its preparation method, which enables more effective stress relaxation during the growth of silicon nitride epitaxial layers, reduces lattice defects, improves lattice quality, and increases the probability of LED light reflection, thereby improving light extraction efficiency.

[0005] In a first aspect, embodiments of the present invention provide a patterned composite substrate based on sponge bumps, comprising:

[0006] Sapphire substrate;

[0007] Multiple sponge-like protrusion microstructures are located on one side of the sapphire substrate in the thickness direction; the sponge-like protrusion microstructures include a sponge skeleton structure, which is made of silicon nitride material and has a three-dimensional interpenetrating network of pores inside.

[0008] Optionally, the sponge protrusion microstructure further includes a filling structure, which fills at least a portion of the pores inside the sponge skeleton structure, and the filling structure is made of silica material.

[0009] Optionally, the sponge-like protrusion microstructure includes a core structure and an outer shell structure, wherein the outer shell structure covers the core structure;

[0010] The sponge skeleton structure includes a first part and a second part, the core structure includes the first part and the filling structure filling the pores inside the first part, and the outer shell structure includes the second part.

[0011] Optionally, the height H3 of the sponge protrusion microstructure satisfies: 1.8μm≤H3≤3.5μm.

[0012] Optionally, the porosity of the sponge skeleton structure satisfy:

[0013] Optionally, the height of the core structure is H4, and the bottom diameter of the core structure is W3; the height of the sponge protrusion microstructure is H3, and the bottom diameter of the sponge protrusion microstructure is W2;

[0014] Wherein, 50% ≤ H4: H3 ≤ 80%; and / or, 50% ≤ W3: W2 ≤ 80%.

[0015] Optionally, the sponge protrusion microstructure further includes a bonding layer located between the sponge skeleton structure and the sapphire substrate; the bonding layer is made of the silicon nitride material.

[0016] Optionally, the thickness H2 of the bonding layer satisfies: 200nm ≤ H2 ≤ 500nm.

[0017] Secondly, embodiments of the present invention also provide a method for fabricating a patterned composite substrate based on sponge bumps, comprising:

[0018] Provides sapphire substrate;

[0019] Multiple sponge-like protrusion microstructures are fabricated on one side of the sapphire substrate in the thickness direction; wherein, the sponge-like protrusion microstructure includes a sponge skeleton structure, which is made of silicon nitride material and has a three-dimensional interpenetrating network of pores inside.

[0020] Optionally, the sponge protrusion microstructure further includes a filling structure, which is made of silicon dioxide material;

[0021] Multiple sponge-like microstructures are fabricated on one side of the sapphire substrate in the thickness direction, including:

[0022] On one side of the sapphire substrate in the thickness direction, the silicon nitride material and the silicon dioxide material are alternately grown in sequence to form a three-dimensional interpenetrating network structure layer;

[0023] The three-dimensional interpenetrating network structure layer is dry etched to form a plurality of sponge protrusion microstructures, and the sponge protrusion structure contains the sponge skeleton structure and a filling structure that fills at least part of the pores inside the sponge skeleton structure.

[0024] Optionally, on one side of the sapphire substrate in the thickness direction, the silicon nitride material and the silicon dioxide material are alternately grown sequentially to form a three-dimensional interpenetrating network structure layer, including an alternately executed first pulse phase and a second pulse phase;

[0025] The first pulse phase includes:

[0026] Using three reaction gases, NH3, SiH4 and N2, in a first preset volume ratio, within a first preset temperature range and a first preset reaction pressure range, a first pulse power is applied, and the reaction is carried out for a first preset duration to grow a columnar β-Si3N4 crystal phase structure.

[0027] The second pulse phase includes:

[0028] Using three reaction gases, N2O, SiH4, and N2, and according to a second preset volume ratio, within a second preset temperature range and a second preset reaction pressure range, a second pulse power is applied, and the reaction lasts for a second preset duration, to grow amorphous SiO2 within the gaps of the columnar β-Si3N4 crystal phase structure.

[0029] Optionally, the first pulse phase and the second pulse phase can be repeated alternately 12 to 30 times.

[0030] Optionally, the sponge-like protrusion microstructure includes a core structure and an outer shell structure, wherein the outer shell structure covers the core structure;

[0031] Dry etching is performed on the three-dimensional interpenetrating network structure layer to form multiple sponge protrusion microstructures. Each sponge protrusion structure contains a sponge skeleton structure and a filling structure that fills at least a portion of the pores within the sponge skeleton structure, including:

[0032] The three-dimensional interpenetrating network structure layer is dry etched to form multiple intermediate protrusion microstructures;

[0033] The sapphire substrate having multiple central protrusion microstructures is immersed in a hydrofluoric acid etching solution, and ultrasonic waves are sent to the surface of the sapphire substrate having the central protrusion microstructures at a preset frequency band to chemically etch the filling structure on the surface of the central protrusion microstructures for a third preset time, so that the sponge skeleton structure forms a first part and a second part. The first part and the filling structure filling the pores inside the first part form the core structure, and the second part forms the outer shell structure.

[0034] Optionally, the sponge protrusion microstructure further includes a bonding layer located between the sponge skeleton structure and the sapphire substrate;

[0035] Before the silicon nitride material and the silicon dioxide material are alternately grown sequentially on one side of the sapphire substrate in the thickness direction to form a three-dimensional interpenetrating network structure layer, the process further includes:

[0036] A solid bonding layer is prepared on one side of the sapphire substrate in the thickness direction using silicon nitride material;

[0037] Dry etching is performed on the three-dimensional interpenetrating network structure layer to form multiple sponge protrusion microstructures. Each sponge protrusion structure contains a sponge skeleton structure and a filling structure that fills at least a portion of the pores within the sponge skeleton structure, including:

[0038] Dry etching is performed on the three-dimensional interpenetrating network structure layer and the whole-layer bonding layer to form a plurality of sponge protrusion microstructures. The sponge protrusion structure contains the bonding layer, the sponge skeleton structure, and a filling structure that fills at least part of the pores inside the sponge skeleton structure.

[0039] This invention proposes a patterned composite substrate structure based on sponge protrusions. A sapphire substrate serves as the support for the sponge protrusion microstructures, ensuring structural stability without obstructing light propagation. Multiple silicon nitride sponge framework structures with sponge protrusions are located on one side of the sapphire substrate surface, containing a three-dimensional interpenetrating network of pores. This structure not only buffers the lateral stress of epitaxial growth using its tapered shape but also achieves loose and elastic properties through the three-dimensional interpenetrating network of pores. Furthermore, it provides a template for stress relaxation and defect annihilation during epitaxial growth, thereby obtaining a low-stress, low-defect epitaxial material layer, improving crystal quality. Simultaneously, it can increase the LED light reflection probability through refractive index transition, thus improving light extraction efficiency. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of a patterned composite substrate structure based on sponge protrusions provided in an embodiment of the present invention;

[0041] Figure 2 This is a schematic diagram of another patterned composite substrate structure based on sponge protrusions provided in an embodiment of the present invention;

[0042] Figure 3 This is a schematic diagram of another patterned composite substrate structure based on sponge protrusions provided in an embodiment of the present invention;

[0043] Figure 4This is a schematic diagram of another patterned composite substrate structure based on sponge protrusions provided in an embodiment of the present invention;

[0044] Figure 5 This is a schematic diagram of another patterned composite substrate structure based on sponge protrusions provided in an embodiment of the present invention;

[0045] Figure 6 This is a flowchart of a method for preparing a patterned composite substrate based on sponge bumps according to an embodiment of the present invention;

[0046] Figure 7 yes Figure 6 The diagram shows the structural flow of a patterned composite substrate based on sponge protrusions.

[0047] Figure 8 This is a flowchart of another method for preparing a patterned composite substrate based on sponge protrusions provided in an embodiment of the present invention;

[0048] Figure 9 This is a flowchart of another method for preparing a patterned composite substrate based on sponge protrusions provided in an embodiment of the present invention;

[0049] Figure 10 This is a flowchart of another method for preparing a patterned composite substrate based on sponge protrusions provided in an embodiment of the present invention;

[0050] Figure 11 yes Figure 10 The diagram shows the structural flow of a patterned composite substrate based on sponge protrusions.

[0051] Figure 12 This is a flowchart of another method for preparing a patterned composite substrate based on sponge protrusions provided in an embodiment of the present invention. Detailed Implementation

[0052] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0053] The terminology used in the embodiments of this invention is for the purpose of describing specific embodiments only and is not intended to limit the invention. It should be noted that directional terms such as "upper," "lower," "left," and "right" described in the embodiments of this invention are used to describe the angles shown in the accompanying drawings and should not be construed as limiting the embodiments of this invention. Furthermore, in the context, it should be understood that when referring to an element being formed "on" or "below" another element, it can be formed not only directly on or below the other element, but also indirectly on or below it through intermediate elements. The terms "first," "second," etc., are used for descriptive purposes only and do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0054] The term "comprising" and its variations as used in this invention are open-ended, meaning "including but not limited to". The term "based on" means "at least partially based on". The term "one embodiment" means "at least one embodiment".

[0055] It should be noted that the concepts of "first" and "second" mentioned in this invention are only used to distinguish the corresponding contents and are not used to limit the order or interdependence.

[0056] It should be noted that the terms "a" and "a plurality of" used in this invention are illustrative rather than restrictive. Those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0057] Figure 1 This is a schematic diagram of a patterned composite substrate structure based on sponge bumps provided in an embodiment of the present invention. (Refer to...) Figure 1 A patterned composite substrate based on sponge bumps includes: a sapphire substrate 10; a plurality of sponge bump microstructures 20 located on one side of the sapphire substrate 10 in the thickness direction; the sponge bump microstructures 20 include a sponge skeleton structure 21, which is made of silicon nitride material and has a three-dimensional interpenetrating network pore inside.

[0058] The substrate refers to the bottom support material constituting the composite substrate, providing a hard and stable physical support for the surface protrusions. Sapphire is chosen as the substrate material because of its strong chemical inertness, high Mohs hardness, high broadband transmittance, and strong resistance to radiation damage, making it the preferred substrate material for heteroepitaxial processes. Multiple sponge-like protrusion microstructures 20 are disposed on one side of the sapphire substrate 10 in the thickness direction. Each sponge-like protrusion microstructure 20 is cone-shaped and includes a sponge skeleton structure 21. Its surface resembles a sponge, covered with interconnected pores. These pores form a three-dimensional interpenetrating network of pores similar to a honeycomb structure. These pores can be filled with air or other heterogeneous materials, and can be completely or partially filled. Therefore, when epitaxial materials are grown in the gaps between the sponge-like protrusion microstructures 20 in the composite substrate, the cone-shaped sponge-like protrusion microstructures 20... The pores in the sponge skeleton structure 21 can release the stress in the transverse direction of the epitaxial material. Furthermore, the incompletely filled sponge skeleton structure 21 not only forms pores on its surface, but the epitaxial material can also fill these pores to a certain extent during growth, releasing some of the growth stress. Simultaneously, the presence of the three-dimensional interpenetrating network pores gives the sponge protrusion microstructure 20 a porous nature, i.e., a certain degree of elasticity. This further buffers the stress during epitaxial material growth, providing an elastic template for stress relaxation and defect annihilation during the growth process, which is beneficial for obtaining a low-stress, low-defect epitaxial layer. In addition, the porous sponge skeleton structure 21 allows for easy adjustment of the refractive index of the sponge protrusion microstructure 20 through porosity, thereby matching the refractive index of the epitaxial layer grown on it, reducing total internal reflection of the light emitted from the LED, increasing the light extraction probability, and improving light extraction efficiency.

[0059] This invention proposes a patterned composite substrate structure based on sponge protrusions. A sapphire substrate serves as the support for the sponge protrusion microstructures, ensuring structural stability without obstructing light propagation. Multiple silicon nitride sponge framework structures with sponge protrusions are located on one side of the sapphire substrate surface, containing a three-dimensional interpenetrating network of pores. This structure not only buffers the lateral stress of epitaxial growth using its tapered shape but also achieves loose and elastic properties through the three-dimensional interpenetrating network of pores. Furthermore, it provides a template for stress relaxation and defect annihilation during epitaxial growth, thereby obtaining a low-stress, low-defect epitaxial material layer, improving crystal quality. Simultaneously, it can increase the LED light reflection probability through refractive index transition, thus improving light extraction efficiency.

[0060] Optional, Figure 2 This is a schematic diagram of another patterned composite substrate structure based on sponge bumps provided in an embodiment of the present invention, for reference. Figure 2 The sponge protrusion microstructure 20 also includes a filling structure 22, which fills at least part of the pores inside the sponge skeleton structure 21. The filling structure 22 is made of silicon dioxide material.

[0061] In this invention, silicon dioxide is used to fill the pores within the sponge skeleton structure 21. These pores can be completely or partially filled; this embodiment of the invention does not limit this. Silicon nitride and silicon dioxide form a composite patterned layer. The refractive index of silicon nitride is approximately 1.9, and that of silicon dioxide is approximately 1.47. The difference in refractive index, combined with air in the pores, creates an adjustable refractive index range. Through the total internal reflection effect at the interface, the light extraction efficiency is further improved. Furthermore, even after the silicon dioxide partially fills the pores, pores still exist on the surface of the sponge protrusion microstructure 20, which can further release the stress generated during the growth of the epitaxial material and effectively suppress dislocation density.

[0062] Optional, Figure 3 This is a schematic diagram of another patterned composite substrate structure based on sponge bumps provided in an embodiment of the present invention, for reference. Figure 3 The sponge protrusion microstructure 20 includes a core structure 23 and an outer shell structure 24, with the outer shell structure 24 covering the core structure 23; the sponge skeleton structure 21 includes a first portion 211 and a second portion 212, the core structure 23 includes the first portion 211 and a filling structure 22 filling the pores inside the first portion 211, and the outer shell structure 24 includes the second portion 212.

[0063] The sponge-like protrusion microstructure 20 is a protrusion unit on the surface of the composite substrate, including a core structure 23 and an outer shell structure 24. The outer shell structure 24 completely covers the core structure 23 from the outside, forming a nested layered structure. The sponge skeleton structure 21 includes two parts: a first part 211 and a second part 212. The first part 211 is the skeleton substrate of the core structure 23 and has a three-dimensional interpenetrating network of pores. The second part 212 constitutes the skeleton body of the outer shell structure 24 and also has a three-dimensional interpenetrating network of pores. The core structure 23 is composed of the silicon nitride skeleton structure of the first part 211 and the filling structure 22. Silicon dioxide can be used as the filling structure 22 to fill some of the pores of the first part 211. The outer shell structure 24 is composed of the silicon nitride porous skeleton of the second part 212. By covering the core structure 23, they together form the morphology of the sponge-like protrusion microstructure 20. In this embodiment, by forming a porous shell structure 24, the sponge protrusion microstructure 20 can be wrapped with a loose and elastic shell. This loose and elastic shell can be used to relax stress during the epitaxial growth process, reduce defects, and improve crystal quality.

[0064] Optionally, the height H3 of the sponge protrusion microstructure 20 satisfies: 1.8μm≤H3≤3.5μm.

[0065] Understandably, a suitable height for the sponge-like protrusion microstructure 20 provides sufficient space for material growth. If the height is less than 1.8 μm, the three-dimensional interpenetrating network pores of the sponge skeleton structure 21 cannot effectively absorb the lattice stress during epitaxial growth, leading to an increase in dislocation density in the GaN epitaxial layer, causing crystal defects and resulting in decreased luminous efficiency. If the height is greater than 3.5 μm, the stability of the sponge-like protrusion microstructure 20 itself decreases, leading to the accumulation of residual stress, causing cracks and bending in the epitaxial layer, and damaging crystal integrity. A suitable height allows the sponge-like protrusion microstructure 20 to play a stress-absorbing role, ensuring high luminous efficiency and high reliability of the LED chip.

[0066] Optionally, the porosity of the sponge skeleton structure 21 satisfy:

[0067] Understandably, the porosity of the sponge skeletal structure 21 determines the refractive index of the sponge protrusion microstructure 20. A suitable porosity... A specific refractive index can be provided for the sponge protrusion microstructure 20, which can be adapted to the refractive index requirements of different products.

[0068] Optionally, the height of the core structure 23 is H4, and the bottom diameter of the core structure 23 is W3; the height of the sponge protrusion microstructure is H3, and the bottom diameter of the sponge protrusion microstructure is W2; wherein, 50% ≤ H4: H3 ≤ 80%; and / or, 50% ≤ W3: W2 ≤ 80%.

[0069] First, the height and bottom diameter of the sponge protrusion microstructure 20 are actually the same as the height and bottom diameter of the outer shell structure 24. In this embodiment, limiting the height ratio of the core structure 23 and the sponge protrusion microstructure 20 to meet the aforementioned numerical range essentially means limiting the height ratio of the core structure 23 and the outer shell structure 24 to meet the aforementioned numerical range. Similarly, limiting the bottom diameter ratio of the core structure 23 and the sponge protrusion microstructure 20 to meet the aforementioned numerical range essentially means limiting the bottom diameter ratio of the core structure 23 and the outer shell structure 24 to meet the aforementioned numerical range. In this embodiment, limiting the height ratio and bottom diameter ratio of the core structure 23 and the outer shell structure 24 to meet the aforementioned numerical range serves two purposes: firstly, it limits the thickness of the outer shell structure 24, ensuring that the surface of the sponge protrusion microstructure 20 has sufficient pores to form a sufficiently loose and elastic shell, thereby effectively releasing the lateral stress during epitaxial growth to the sides of the sponge protrusion microstructure 20; secondly, it allows adjustment of the refractive index of the sponge protrusion microstructure 20 to adapt to the refractive index requirements of different products, improving the light emission effect.

[0070] Optional, Figure 4 This is a schematic diagram of another patterned composite substrate structure based on sponge bumps provided in an embodiment of the present invention, for reference. Figure 4The sponge protrusion microstructure 20 also includes a bonding layer 25, which is located between the sponge skeleton structure 21 and the sapphire substrate 10; the bonding layer 25 is made of silicon nitride material.

[0071] The bonding layer 25 is located between the sponge framework structure 21 and the sapphire substrate 10, and is made of silicon nitride. Silicon nitride has a refractive index of approximately 1.9, creating a refractive index difference between the different materials, which increases the probability of photon escape. Simultaneously, because silicon nitride is not corroded by hydrofluoric acid, it provides a solid foundation for the bonding between the protruding structure and the sapphire surface, preventing the bonding force from being destroyed by hydrofluoric acid. Furthermore, both the central core structure 23 and the outer core structure 24 use silicon nitride as the framework material, making the connection between each part more stable and enhancing the overall connection reliability of the sponge protruding microstructure 20.

[0072] Optionally, the thickness H2 of the bonding layer 25 satisfies: 200nm ≤ H2 ≤ 500nm.

[0073] Understandably, the thickness of the bonding layer 25 should be within a suitable range. If the bonding layer 25 is too thin, the interfacial bonding will be weak, and the sponge skeleton structure 21 will easily peel off from the sapphire surface during subsequent hydrofluoric acid cleaning, resulting in poor stability. It will also easily cause photons to be reflected back into the chip from the interface, reducing the escape probability. If the bonding layer 25 is too thick, stress accumulation will increase internal defects, reducing the light extraction efficiency of the LED chip. A suitable thickness of the bonding layer 25 allows for a stable bond between the sapphire substrate 10 and the sponge protrusion microstructure 20, improving the stability of the composite substrate.

[0074] Optional, Figure 5 This is a schematic diagram of another patterned composite substrate structure based on sponge bumps provided in an embodiment of the present invention, for reference. Figure 5 The sponge protrusion microstructure 20 also includes a sapphire layer 26, which is integrally connected to the sapphire substrate 10, and the sponge skeleton structure 21 is located on the side of the sapphire layer 26 away from the sapphire substrate 10.

[0075] In the process of preparing the sponge protrusion microstructure 20 by dry etching, it is necessary to over-etch and destroy part of the sapphire substrate 10 area to expose the covered sapphire substrate, thereby ensuring that the epitaxial material grows on the exposed sapphire substrate surface.

[0076] Optionally, the thickness H1 of the sapphire layer 26 satisfies: H1≥150nm.

[0077] Understandably, a sufficiently thick sapphire layer 26 can ensure that the heterostructure at each site on the substrate surface is etched through to the sapphire layer 26 and exposes the C-face of the sapphire, thus avoiding epitaxial failure and fogging.

[0078] Optionally, the multiple sponge protrusion microstructures 20 are arranged periodically, and the arrangement period T of the sponge protrusion microstructures 20 satisfies: 2.0μm≤T≤5.0μm; and / or, the gap D between adjacent sponge protrusion microstructures 20 satisfies: D≥0.2μm.

[0079] The multiple sponge-like protrusion microstructures 20 are arranged periodically, forming an ordered light-scattering array on the chip surface. If the arrangement period is too small, the light will be excessively scattered and absorbed by the material due to the overly dense structure; if the arrangement period is too large, the light extraction efficiency will be reduced. At the same time, the gaps of more than 0.2 μm can prevent the sponge-like protrusion microstructures 20 from sticking together, so that the light will form a total internal reflection effect at the interface, improving the light extraction efficiency of the LED chip and providing a complete C-plane space for the subsequent GaN epitaxial crystallization.

[0080] Figure 6 This invention provides a flowchart of a method for fabricating a patterned composite substrate based on sponge bumps. Figure 7 yes Figure 6 The diagram shown is a flow chart of a patterned composite substrate based on sponge bumps. (Refer to...) Figure 6 and Figure 7 The fabrication method of patterned composite substrates based on sponge bumps includes:

[0081] S110 provides a sapphire substrate.

[0082] refer to Figure 7 Figure (a) shows that this step utilizes the characteristics of sapphire, such as strong chemical inertness, high Mohs hardness, high broadband light transmittance, and strong resistance to radiation damage, to select sapphire as the preferred substrate material for preparing composite substrates.

[0083] S120: Multiple sponge-like microstructures are prepared on one side of the sapphire substrate in the thickness direction.

[0084] The surface of the multiple sponge-like protrusion microstructures 20 resembles a sponge, covered with interconnected pores. These pores form a three-dimensional interpenetrating network of pores, similar to a honeycomb structure. This porous structure allows the cone-shaped sponge-like protrusion microstructures 20 to effectively buffer the stress generated during lateral growth of the underlying material, which is beneficial for obtaining epitaxial materials with low stress and low defects. The sponge skeleton structure 21 is made of silicon nitride material, forming a composite patterned layer of air and silicon nitride. The difference in refractive index between air and silicon nitride can improve light extraction efficiency.

[0085] As in the above embodiment, the sponge protrusion microstructure 20 also includes a filling structure 22, which is made of silicon dioxide material. Figure 8 This is a flowchart of another method for fabricating a patterned composite substrate based on sponge bumps provided in an embodiment of the present invention. Optional, refer to... Figure 8 This embodiment is an optimization based on the above embodiment. Specifically, multiple sponge-like microstructures are fabricated on one side of the sapphire substrate in the thickness direction. This can be further refined as follows:

[0086] On one side of the sapphire substrate along its thickness direction, silicon nitride and silicon dioxide materials are alternately grown to form a three-dimensional interpenetrating network structure layer.

[0087] Dry etching is performed on the three-dimensional interpenetrating network structure layer to form multiple sponge protrusion microstructures, and the sponge protrusion structure contains a sponge skeleton structure and a filling structure that fills at least part of the pores inside the sponge skeleton structure.

[0088] like Figure 8 As shown, the method may include the following steps:

[0089] S210 provides a sapphire substrate.

[0090] S220: Multiple sponge-like microstructures are fabricated on one side of the sapphire substrate in the thickness direction.

[0091] S230: On one side of the sapphire substrate in the thickness direction, silicon nitride and silicon dioxide materials are alternately grown to form a three-dimensional interpenetrating network structure layer.

[0092] refer to Figure 7 Figure (b) shows that on one side of the sapphire substrate 10 along its thickness direction, silicon nitride material is generated through a gas ratio reaction. The silicon nitride material is deposited onto the surface of the substrate. This process is not a simple physical deposition; the surface of the sapphire substrate 10 has a rough and undulating structure. During the reaction, many crystal nuclei are generated. Through continuous reaction, diffusion, and fusion, the crystal nuclei form an irregular silicon nitride network structure. After a period of time, the gas ratio is changed, and the deposited material is replaced with silicon dioxide, causing silicon dioxide material to be deposited into the gaps of the silicon nitride network structure. By continuously repeating the above process, a three-dimensional interpenetrating network structure layer 30 with silicon nitride as the framework structure and silicon dioxide as the interstitial filler is finally formed.

[0093] S240. The three-dimensional interpenetrating network structure layer is dry-etched to form multiple sponge protrusion microstructures, and the sponge protrusion structure contains a sponge skeleton structure and a filling structure that fills at least part of the pores inside the sponge skeleton structure.

[0094] refer to Figure 7Figure (c) shows that photoresist is coated on a portion of the upper side of the three-dimensional interpenetrating network structure layer 30 to form a first photoresist layer 40. The second photoresist layer 40 in this step can also use positive or negative photoresist, and the coating process can be spin coating, spray coating, or formed using magnetron sputtering or plasma-enhanced chemical vapor deposition. This embodiment of the invention does not limit the type of photoresist; this embodiment uses negative photoresist as an example for specific explanation.

[0095] refer to Figure 7 As shown in Figure (d), on the upper side of the three-dimensional interpenetrating network structure layer 30, after the negative photoresist is coated on the substrate surface and exposed, the illuminated areas undergo a curing reaction to form a solid structure insoluble in the developer. Meanwhile, the unexposed areas are selectively dissolved and removed by the developer during the development process, thus partially preserving the pattern. The cured structure forms the photoresist pillar mask layer 50. During subsequent etching, the photoresist pillar mask layer 50 protects the internally cured structure and reduces the etching rate of the underlying structure.

[0096] refer to Figure 7 Figure (e) shows that the three-dimensional interpenetrating network structure layer 30 is dry etched. Due to the presence of the adhesive pillar mask layer 50, the gaps are etched first, and the protrusions are etched later, ultimately forming the sponge protrusion microstructure 20.

[0097] Optionally, silicon nitride and silicon dioxide materials are alternately grown sequentially on one side of the sapphire substrate 10 in the thickness direction to form a three-dimensional interpenetrating network structure layer 30, including an alternately executed first pulse stage and a second pulse stage.

[0098] The first pulse phase includes:

[0099] Using three reaction gases, NH3, SiH4 and N2, in a first preset volume ratio, within a first preset temperature range and a first preset reaction pressure range, a first pulse power is applied, and the reaction is carried out for a first preset duration to grow a columnar β-Si3N4 crystal phase structure.

[0100] The second pulse phase includes:

[0101] Using three reaction gases, N2O, SiH4 and N2, and according to a second preset volume ratio, within a second preset temperature range and a second preset reaction pressure range, a second pulse power is applied for a second preset reaction time to grow amorphous SiO2 in the gaps of the columnar β-Si3N4 crystal phase structure.

[0102] The first preset volume ratio of the three reacting gases NH3, SiH4, and N2 can be NH3:SiH4:N2 = 1:2:8, the first preset temperature range can be 380±20℃, the first preset reaction pressure range can be 1500±200mTorr, the first pulse power can be 1200W, and the first preset duration can be 10–25s / cycle. The second preset volume ratio of the three reacting gases N2O, SiH4, and N2 can be N2O:SiH4:N2 = 5:1:3, the second preset reaction pressure range can be 800±100mTorr, the second pulse power can be 800W, and the second preset duration can be 10–45s / cycle.

[0103] Gradient composite formation of silicon nitride framework and silicon dioxide filler was achieved through pulsed gas switching. High-frequency power modulation was used to induce preferential growth of columnar crystals, improving mechanical support. By adjusting the ratio of the first preset duration to the second preset duration, the refractive index could be changed, thereby improving light extraction efficiency.

[0104] Optionally, the first pulse phase and the second pulse phase can be repeated alternately 12 to 30 times.

[0105] It is understandable that a single pulse stage can only form a single layer of columnar silicon nitride or silicon dioxide interface. Repeated alternation can make silicon nitride and silicon dioxide closely arranged, improve bending strength, and thus improve light extraction efficiency. Pulses exceeding 30 times will lead to excessively long deposition time, excessively close arrangement of silicon nitride and silicon dioxide, reduced porosity, and consequently reduced stress buffering capacity and decreased light extraction efficiency.

[0106] As in the above embodiment, the sponge protrusion microstructure 20 includes a core structure 23 and an outer shell structure 24, with the outer shell structure 24 covering the core structure 23. Figure 9 This is a flowchart illustrating another method for fabricating a patterned composite substrate based on sponge bumps, provided in an embodiment of the present invention. Optionally, refer to... Figure 9 This embodiment is an optimization based on the above embodiment. Specifically, the three-dimensional interpenetrating network structure layer is dry-etched to form multiple sponge protrusion microstructures. Each sponge protrusion structure contains a sponge skeleton structure and filling structures that fill at least some of the pores within the sponge skeleton structure. More specifically, it can be refined as follows:

[0107] Dry etching was performed on the three-dimensional interpenetrating network structure layer to form multiple intermediate protrusion microstructures.

[0108] A sapphire substrate with multiple central protrusion microstructures is immersed in a hydrofluoric acid etching solution. Ultrasonic waves are sent to the surface of the sapphire substrate with the central protrusion microstructures at a preset frequency band to chemically etch the filling structure on the surface of the central protrusion microstructures for a third preset time, so that the sponge skeleton structure forms a first part and a second part. The first part and the filling structure filling the pores inside the first part form a core structure, and the second part forms an outer shell structure.

[0109] like Figure 9 As shown, the method may include the following steps:

[0110] S310 provides a sapphire substrate.

[0111] S320: Multiple sponge-like microstructures are fabricated on one side of the sapphire substrate in the thickness direction.

[0112] S330: On one side of the sapphire substrate in the thickness direction, silicon nitride and silicon dioxide materials are alternately grown to form a three-dimensional interpenetrating network structure layer.

[0113] S340. The three-dimensional interpenetrating network structure layer is dry-etched to form multiple sponge protrusion microstructures, and the sponge protrusion structure contains a sponge skeleton structure and a filling structure that fills at least part of the pores inside the sponge skeleton structure.

[0114] S350: Dry etching is performed on the three-dimensional interpenetrating network structure layer to form multiple intermediate protrusion microstructures.

[0115] In this step, the three-dimensional interpenetrating network structure layer 30 is processed into multiple intermediate protrusion microstructures by dry etching. On the one hand, the geometric morphology of the intermediate protrusion microstructures can be controlled, and the light extraction efficiency can be improved by utilizing the difference in refractive index between silicon nitride and silicon dioxide. On the other hand, by forming a porous skeleton structure, a supporting framework is provided for the subsequent filling process, thereby achieving epitaxial stress buffering and structural stability enhancement.

[0116] S360. Immerse a sapphire substrate with multiple central protrusion microstructures in a hydrofluoric acid etching solution, and send ultrasonic waves to the surface of the sapphire substrate with central protrusion microstructures facing the substrate at a preset frequency band to chemically etch the filling structure on the surface of the central protrusion microstructures for a third preset time, so that the sponge skeleton structure forms a first part and a second part. The first part and the filling structure filling the pores inside the first part form a core structure, and the second part forms a shell structure.

[0117] refer to Figure 7Figure (f) shows a sapphire substrate 10 with multiple central protrusion microstructures immersed in a hydrofluoric acid etching solution. The hydrofluoric acid reacts with silicon dioxide but not with silicon nitride, causing the sponge skeleton structure 21 to form a first part 211 and a second part 212. The first part 211 and the filling structure 22 filling the pores inside the first part 211 form a core structure 23, including a composite patterned layer of silicon nitride and silicon dioxide. The second part 212 forms an outer shell structure 24. The silicon dioxide on the surface of the second part 212 reacts with hydrofluoric acid to form a porous outer ring layer of silicon nitride sponge.

[0118] The third preset duration can be 30 to 45 minutes. By adjusting the third preset duration, the height ratio and bottom aperture ratio of the core structure 23 and the outer core structure 24 can be adjusted, thereby adjusting the light extraction efficiency.

[0119] Optionally, the preset frequency band f satisfies: 0.8MHz≤f≤1.2MHz.

[0120] Understandably, ultrasound at appropriate frequencies is beneficial for the chemical reaction of the filling material within the gap.

[0121] As in the above embodiment, the sponge protrusion microstructure 20 also includes a bonding layer 25, which is located between the sponge skeleton structure 21 and the sapphire substrate 10. Figure 10 This is a flowchart illustrating another method for fabricating a patterned composite substrate based on sponge bumps, provided in an embodiment of the present invention. Figure 11 yes Figure 10 The diagram shown is a flow chart of a patterned composite substrate based on sponge bumps. Optional, refer to [reference needed]. Figure 10 and Figure 11 This embodiment is an optimization based on the above embodiment. Specifically, before alternatingly growing silicon nitride and silicon dioxide materials on one side of the sapphire substrate in the thickness direction to form a three-dimensional interpenetrating network structure layer, the following steps can be added:

[0122] A solid bonding layer is prepared on one side of the sapphire substrate in the thickness direction using silicon nitride material.

[0123] Specifically, the three-dimensional interpenetrating network structure layer is dry-etched to form multiple sponge-like protrusion microstructures. These protrusions contain a sponge skeleton structure and filling structures that fill at least some of the pores within the sponge skeleton structure. More specifically, this can be further refined as follows:

[0124] Dry etching is performed on the three-dimensional interpenetrating network structure layer and the integral bonding layer to form multiple sponge protrusion microstructures. The sponge protrusion structure contains a bonding layer, a sponge skeleton structure, and a filling structure that fills at least part of the pores inside the sponge skeleton structure.

[0125] like Figure 10 As shown, the method may include the following steps:

[0126] S410 provides a sapphire substrate.

[0127] S420: Multiple sponge-like microstructures are fabricated on one side of the sapphire substrate in the thickness direction.

[0128] S430: A solid bonding layer is prepared on one side of the sapphire substrate in the thickness direction using silicon nitride material.

[0129] refer to Figure 11 As shown in Figure (b), the integral bonding layer 25 prepared in this step is located between the sponge skeleton structure 21 and the sapphire substrate 10. It can create a refractive index difference between different materials, which can increase the probability of photon escape. At the same time, since silicon nitride is not corroded by hydrofluoric acid, it can lay a solid foundation for the bonding between the protruding structure and the upper surface of the sapphire, so that the bonding force between the two is not destroyed by hydrofluoric acid, thus strengthening the stability of the composite substrate.

[0130] S440: On one side of the sapphire substrate in the thickness direction, silicon nitride and silicon dioxide materials are alternately grown to form a three-dimensional interpenetrating network structure layer.

[0131] S450. Dry etching is performed on the three-dimensional interpenetrating network structure layer and the whole-layer bonding layer to form multiple sponge protrusion microstructures. The sponge protrusion structure contains a bonding layer, a sponge skeleton structure, and a filling structure that fills at least part of the pores inside the sponge skeleton structure.

[0132] refer to Figure 11 Figure (f) shows that the three-dimensional interpenetrating network structure layer 30 and the integral bonding layer 25 are dry etched, which makes the connection between each part more stable and enhances the overall connection reliability of the sponge protrusion microstructure 20.

[0133] S460: Dry etching is performed on the three-dimensional interpenetrating network structure layer and the whole-layer bonding layer to form multiple intermediate protrusion microstructures.

[0134] S470. Immerse a sapphire substrate with multiple central protrusion microstructures in a hydrofluoric acid etching solution, and send ultrasonic waves to the surface of the sapphire substrate with central protrusion microstructures facing the substrate at a preset frequency band to chemically etch the filling structure on the surface of the central protrusion microstructures for a third preset time, so that the sponge skeleton structure forms a first part and a second part. The first part and the filling structure filling the pores inside the first part form a core structure, and the second part forms a shell structure.

[0135] As in the above embodiment, the sponge protrusion microstructure 20 also includes a sapphire layer 26, which is integrally connected to the sapphire substrate 10, and the sponge skeleton structure 21 is located on the side of the sapphire layer 26 away from the sapphire substrate 10. Figure 12 This is a flowchart illustrating another method for fabricating a patterned composite substrate based on sponge bumps, provided in an embodiment of the present invention. Optionally, refer to... Figure 12 This embodiment is an optimization based on the above embodiment. Specifically, the three-dimensional interpenetrating network structure layer is dry-etched to form multiple sponge protrusion microstructures. Each sponge protrusion structure contains a sponge skeleton structure and filling structures that fill at least some of the pores within the sponge skeleton structure. More specifically, it can be refined as follows:

[0136] The three-dimensional interpenetrating network structure layer is over-etched to form multiple sponge protrusion microstructures, and the sponge protrusion structure contains a sapphire layer, a sponge skeleton structure, and a filling structure that fills at least part of the pores inside the sponge skeleton structure.

[0137] like Figure 12 As shown, the method may include the following steps:

[0138] S510, provides a sapphire substrate.

[0139] S520: Multiple sponge-like microstructures are fabricated on one side of the sapphire substrate in the thickness direction.

[0140] S530: On one side of the sapphire substrate in the thickness direction, silicon nitride and silicon dioxide materials are alternately grown to form a three-dimensional interpenetrating network structure layer.

[0141] S540. The three-dimensional interpenetrating network structure layer is over-etched to form multiple sponge protrusion microstructures, and the sponge protrusion structure contains a sapphire layer, a sponge skeleton structure, and a filling structure that fills at least part of the pores inside the sponge skeleton structure.

[0142] During dry etching of the three-dimensional interpenetrating network structure layer 30, some areas of the sapphire substrate 10 are also over-etched, causing the un-etched sapphire areas to protrude and form the sapphire layer 26. The sapphire layer 26 can serve as a transition structure between the sapphire substrate 10 and the sponge-like protruding microstructure 20. By utilizing the chemical inertness and structural stability of sapphire, it strengthens the bond between the sponge-like skeleton structure 21 and the sapphire substrate 10, buffers stress, and improves the stability of the structure.

[0143] S550, dry etching is performed on the three-dimensional interpenetrating network structure layer to form multiple intermediate protrusion microstructures.

[0144] S560. Immerse a sapphire substrate with multiple central protrusion microstructures in a hydrofluoric acid etching solution, and send ultrasonic waves to the surface of the sapphire substrate with central protrusion microstructures facing the substrate at a preset frequency band to chemically etch the filling structure on the surface of the central protrusion microstructures for a third preset time, so that the sponge skeleton structure forms a first part and a second part. The first part and the filling structure filling the pores inside the first part form a core structure, and the second part forms a shell structure.

[0145] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, combinations, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A patterned composite substrate based on sponge protrusions, characterized in that, include: Sapphire substrate; Multiple sponge-like protrusion microstructures are located on one side of the sapphire substrate in the thickness direction; the sponge-like protrusion microstructures include a sponge skeleton structure, which is made of silicon nitride material and has a three-dimensional interpenetrating network of pores inside. The sponge protrusion microstructure also includes a filling structure, which fills at least a portion of the pores inside the sponge skeleton structure, and the filling structure is made of silicon dioxide material. The sponge-like protrusion microstructure includes a core structure and an outer shell structure, wherein the outer shell structure covers the core structure. The sponge skeleton structure includes a first part and a second part, the core structure includes the first part and the filling structure filling the pores inside the first part, and the outer shell structure includes the second part.

2. The patterned composite substrate according to claim 1, characterized in that, The height H of the sponge protrusion microstructure satisfies: 1.8μm≤H3≤3.5μm.

3. The patterned composite substrate according to claim 1, characterized in that, The porosity φ of the sponge skeleton structure satisfies: 20%≤φ≤25%.

4. The patterned composite substrate according to claim 1, characterized in that, The height of the core structure is H4, and the bottom diameter of the core structure is W3; the height of the sponge protrusion microstructure is H3, and the bottom diameter of the sponge protrusion microstructure is W2. Wherein, 50%≤H4:H3≤80%; and / or, 50%≤W3:W2≤80%.

5. The patterned composite substrate according to claim 1, characterized in that, The sponge protrusion microstructure also includes a bonding layer, which is located between the sponge skeleton structure and the sapphire substrate; the bonding layer is made of the silicon nitride material.

6. The patterned composite substrate according to claim 5, characterized in that, The thickness H2 of the bonding layer satisfies: 200nm≤H2≤500nm.

7. A method for fabricating a patterned composite substrate based on sponge bumps, characterized in that, include: Provides sapphire substrate; Multiple sponge-like protrusion microstructures are fabricated on one side of the sapphire substrate in the thickness direction; wherein, the sponge-like protrusion microstructure includes a sponge skeleton structure, which is made of silicon nitride material and has a three-dimensional interpenetrating network of pores inside. The sponge protrusion microstructure also includes a filling structure, which is made of silicon dioxide material; Multiple sponge-like microstructures are fabricated on one side of the sapphire substrate in the thickness direction, including: On one side of the sapphire substrate in the thickness direction, the silicon nitride material and the silicon dioxide material are alternately grown in sequence to form a three-dimensional interpenetrating network structure layer; The three-dimensional interpenetrating network structure layer is dry etched to form a plurality of sponge protrusion microstructures, and the sponge protrusion structure contains the sponge skeleton structure and a filling structure that fills at least part of the pores inside the sponge skeleton structure. The sponge-like protrusion microstructure includes a core structure and an outer shell structure, wherein the outer shell structure covers the core structure. Dry etching is performed on the three-dimensional interpenetrating network structure layer to form multiple sponge protrusion microstructures. Each sponge protrusion structure contains a sponge skeleton structure and a filling structure that fills at least a portion of the pores within the sponge skeleton structure, including: The three-dimensional interpenetrating network structure layer is dry etched to form multiple intermediate protrusion microstructures; The sapphire substrate having multiple central protrusion microstructures is immersed in a hydrofluoric acid etching solution, and ultrasonic waves are sent to the surface of the sapphire substrate having the central protrusion microstructures at a preset frequency band to chemically etch the filling structure on the surface of the central protrusion microstructures for a third preset time, so that the sponge skeleton structure forms a first part and a second part. The first part and the filling structure filling the pores inside the first part form the core structure, and the second part forms the outer shell structure.

8. The preparation method according to claim 7, characterized in that, On one side of the sapphire substrate in the thickness direction, the silicon nitride material and the silicon dioxide material are alternately grown sequentially to form a three-dimensional interpenetrating network structure layer, including an alternately executed first pulse phase and a second pulse phase; The first pulse phase includes: Using three reaction gases, NH3, SiH4 and N2, in a first preset volume ratio, within a first preset temperature range and a first preset reaction pressure range, a first pulse power is applied, and the reaction is carried out for a first preset duration to grow a columnar β-Si3N4 crystal phase structure. The second pulse phase includes: Using three reaction gases, N2O, SiH4, and N2, and according to a second preset volume ratio, within a second preset temperature range and a second preset reaction pressure range, a second pulse power is applied, and the reaction lasts for a second preset duration, to grow amorphous SiO2 within the gaps of the columnar β-Si3N4 crystal phase structure.

9. The preparation method according to claim 8, characterized in that, Repeat the first pulse phase and the second pulse phase alternately 12 to 30 times.

10. The preparation method according to claim 7, characterized in that, The sponge protrusion microstructure also includes a bonding layer, which is located between the sponge skeleton structure and the sapphire substrate; Before the silicon nitride material and the silicon dioxide material are alternately grown sequentially on one side of the sapphire substrate in the thickness direction to form a three-dimensional interpenetrating network structure layer, the process further includes: A solid bonding layer is prepared on one side of the sapphire substrate in the thickness direction using silicon nitride material; Dry etching is performed on the three-dimensional interpenetrating network structure layer to form multiple sponge protrusion microstructures. Each sponge protrusion structure contains a sponge skeleton structure and a filling structure that fills at least a portion of the pores within the sponge skeleton structure, including: Dry etching is performed on the three-dimensional interpenetrating network structure layer and the whole-layer bonding layer to form a plurality of sponge protrusion microstructures. The sponge protrusion structure contains the bonding layer, the sponge skeleton structure, and a filling structure that fills at least part of the pores inside the sponge skeleton structure.

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