Light-emitting chip and preparation method thereof

Abstract

The invention discloses a light-emitting chip and a preparation method thereof, and the light-emitting chip comprises the components of a driving substrate which comprises a first surface and a second surface which are oppositely arranged; the first surface comprises at least one electrode contact; the at least one light-emitting unit is located on the first surface of the driving substrate, and each light-emitting unit can be independently driven by the corresponding electrode contact; wherein the light-emitting unit comprises a light-emitting epitaxial structure, the light-emitting epitaxial structure is in a ball table shape, and the top surface area of the light-emitting epitaxial structure is smaller than the bottom surface area of the light-emitting epitaxial structure. According to the technical scheme provided by the invention, the luminous efficiency of the luminous chip is improved.

Description

Technical Field

[0001] This invention relates to the field of display technology, and more particularly to a light-emitting chip and its fabrication method. Background Technology

[0002] Display technology, as a key carrier of information exchange and intelligent interaction, is constantly evolving with the deepening development of an information-based and intelligent society. Among many emerging display technologies, Micro LED (micron-level light-emitting diode) display technology is regarded as a next-generation display solution with disruptive potential due to its superior performance in brightness, contrast, power consumption, and lifespan, and it shows broad application prospects in cutting-edge fields such as augmented reality (AR), near-eye display (NED), and wearable devices.

[0003] The core feature of Micro LED light-emitting chips is the integration of a high-density, micrometer-scale two-dimensional array of pixel light-emitting units onto a single chip. Currently, most mainstream Micro LED chips employ a columnar or inverted trapezoidal structure, and their manufacturing process primarily relies on traditional planar semiconductor processes and dry etching techniques. To improve light extraction efficiency, existing technologies typically design the chip sidewalls with a tilted shape. However, even when the sidewall tilt angle is reduced to around 85°, research shows that approximately 40% of photons are still absorbed by the material after multiple reflections within the chip, resulting in a significant reduction in optical efficiency. Therefore, improving the luminous efficiency of light-emitting chips has become a pressing technical problem to be solved in this field. Summary of the Invention

[0004] This invention provides a light-emitting chip and its fabrication method to improve the light extraction efficiency of the light-emitting chip.

[0005] According to one aspect of the present invention, a light-emitting chip is provided, comprising: A driving substrate includes a first surface and a second surface disposed opposite to each other; the first surface includes at least one electrode contact. At least one light-emitting unit is located on the first surface of the driving substrate, and each light-emitting unit can be individually driven by the corresponding electrode contact. The light-emitting unit includes a light-emitting epitaxial structure, which is shaped like a frustum, and the top surface area of ​​the light-emitting epitaxial structure is smaller than the bottom surface area of ​​the light-emitting epitaxial structure.

[0006] Optionally, the angle between the arcuate sidewall of the light-emitting epitaxial structure and the bottom surface of the light-emitting epitaxial structure is less than or equal to 80° and greater than or equal to 50°.

[0007] Optionally, the light-emitting chip further includes: At least one microlens is located on the side of the light-emitting unit away from the driving substrate and on the sidewall of the light-emitting unit; The microlens is formed in a frustum shape based on the light-emitting epitaxial structure using inorganic or organic dielectric materials.

[0008] Optionally, the light-emitting epitaxial structure includes: The first semiconductor layer is located on one side of the driving substrate; The light-emitting layer is located on the side of the first semiconductor layer away from the driving substrate; The second semiconductor layer is located on the side of the light-emitting layer away from the driving substrate; The first semiconductor layer and the second semiconductor layer have different conductivity types.

[0009] Optionally, the light-emitting unit further includes: A first electrode is located between the light-emitting epitaxial structure and the driving substrate; the first electrode is electrically connected to the electrode contact; and / or... The second electrode is located on the side of the light-emitting epitaxial structure away from the driving substrate; The first electrode is made of metal, and the second electrode is made of transparent conductive material.

[0010] Optionally, the overall structure formed by the second electrode and the light-emitting epitaxial structure is frustum-shaped.

[0011] Optionally, the light-emitting chip further includes: A passivation layer is located on the sidewall of the light-emitting unit and on the first surface of the driving substrate not covered by the light-emitting unit; An electrode connection layer is located on the surface of the passivation layer away from the light-emitting epitaxial structure, the surface of the passivation layer away from the driving substrate, and the surface of the second electrode away from the light-emitting epitaxial structure. An ohmic contact layer is located between the first electrode and the first semiconductor; the materials of the ohmic contact layer, the electrode connection layer, and the second electrode all include zinc tin oxide. The lower surface contour of the microlens in the light-emitting chip is adapted to the upper surface contour of the electrode connection layer.

[0012] According to another aspect of the present invention, a method for fabricating a light-emitting chip is provided, for fabricating the light-emitting chip described in any embodiment of the present invention, comprising: A substrate is provided, and an epitaxial layer is formed on the substrate; The driving substrate is bonded to the epitaxial layer on the side away from the substrate, and the substrate is removed; A composite mask is formed on the side of the epitaxial layer away from the driving substrate, and the composite mask is patterned. Based on the patterned composite mask, a frustum-shaped epitaxial light-emitting structure is formed, and the top surface area of ​​the light-emitting epitaxial structure is smaller than the bottom surface area of ​​the light-emitting epitaxial structure.

[0013] Optionally, bonding the driving substrate to the side of the epitaxial layer away from the substrate includes: A first bonding sublayer is formed on the side of the epitaxial layer away from the substrate; A second bonding layer is formed on the first surface of the driving substrate; The driving substrate is bonded to the epitaxial layer on the side away from the substrate through the first bonding sublayer and the second bonding sublayer; the first bonding sublayer and the second bonding sublayer form a bonding layer; After forming a frustum-shaped epitaxial light-emitting structure based on the patterned composite mask, the process also includes: The bonding layer is etched to form a first electrode; the first electrode is located between the light-emitting epitaxial structure and the driving substrate.

[0014] Optionally, before forming the composite mask on the side of the epitaxial layer away from the driving substrate, the method further includes: A second electrode material layer is formed on the surface of the epitaxial layer away from the driving substrate; a composite mask is formed on the surface of the second electrode material layer away from the epitaxial layer. Based on the patterned composite mask, while forming a frustum-shaped epitaxial light-emitting structure, it also includes: A second electrode is formed; the overall structure formed by the second electrode and the light-emitting epitaxial structure is frustum-shaped.

[0015] Optionally, the method for fabricating the light-emitting chip further includes: Based on the shape of the light-emitting epitaxial structure, microlenses are formed on the side of the light-emitting unit away from the driving substrate and on the sidewall of the light-emitting unit by a deposition process.

[0016] The technical solution provided by this invention sets the light-emitting epitaxial structure in the shape of a frustum, giving the sidewalls of the light-emitting epitaxial structure a continuously changing sidewall curve and a platform at the top. This frustum shape, occupying the same base area and top area, has a larger active area (light-emitting layer) volume than a frustum-shaped or prismatic structure, thereby improving the potential for light output power. Furthermore, its gently sloping, continuously inclined sidewall profile provides superior "climbing" capability for subsequent passivation and reflective film deposition, ensuring the continuity and uniformity of the coating and enhancing sidewall passivation and light reflection effects. More importantly, this invention fully utilizes the small platform at the top of the frustum-shaped MESA and its smoothly transitioning sidewalls, allowing for direct self-assembly of microlens structures. This method eliminates the complex steps of additionally fabricating and aligning bonding microlenses on a flat chip surface, as required by traditional processes, achieving integrated MESA structure and microlens. This self-assembled microlens can more effectively collect and export light emitted from the active area, especially large-angle light, thereby significantly optimizing the chip's light extraction efficiency. Therefore, setting the light-emitting epitaxial structure to a frustum shape can improve the light extraction efficiency of the light-emitting chip in many ways.

[0017] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention, 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 the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of a light-emitting chip provided in an embodiment of the present invention; Figure 2 This is a flowchart of a method for fabricating a light-emitting chip according to an embodiment of the present invention; Figures 3-4 This is a schematic cross-sectional view of step S210 in a method for fabricating a light-emitting chip according to an embodiment of the present invention. Figure 5 This is a schematic cross-sectional view of step S220 in a method for fabricating a light-emitting chip according to an embodiment of the present invention. Figure 6 This is a schematic cross-sectional view of step S230 in a method for fabricating a light-emitting chip according to an embodiment of the present invention. Figure 7This is a schematic cross-sectional view of step S320 in a method for fabricating a light-emitting chip according to an embodiment of the present invention. Figure 8 This is a schematic cross-sectional view of step S330 in a method for fabricating a light-emitting chip according to an embodiment of the present invention. Figure 9 This is a schematic cross-sectional view of step S40 in a method for fabricating a light-emitting chip according to an embodiment of the present invention. Figure 10 This is a schematic cross-sectional view of step S50 in a method for fabricating a light-emitting chip according to an embodiment of the present invention. Figure 11 This is a schematic cross-sectional view of step S60 in a method for fabricating a light-emitting chip according to an embodiment of the present invention. Figure 12 This is a cross-sectional structural diagram corresponding to step S70 in a method for fabricating a light-emitting chip according to an embodiment of the present invention. Detailed Implementation

[0020] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0021] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0022] This invention provides a light-emitting chip. Figure 1 This is a schematic diagram of the structure of a light-emitting chip provided in an embodiment of the present invention, for reference. Figure 1 The light-emitting chip includes: The driving substrate 10 includes a first surface and a second surface disposed opposite to each other; the first surface includes at least one electrode contact. At least one light-emitting unit 20 is located on the first surface of the driving substrate 10, and each light-emitting unit 20 can be driven individually by a corresponding electrode contact. The light-emitting unit 20 includes a light-emitting epitaxial structure 23, which is shaped like a frustum and has a top surface area smaller than its bottom surface area.

[0023] Specifically, the driving substrate 10 can be a CMOS (Complementary Metal Oxide Semiconductor) driving backplane or a TFT (Thin Film Transistor) driving backplane. The driving substrate 10 can include a substrate and a driving structure layer disposed on the substrate. The driving structure layer includes PMOS and / or NMOS, and also includes driving electrodes 11 connected to corresponding transistors. The driving electrodes 11 are used to drive the light-emitting unit 20 to emit light. The driving electrodes 11 can be columnar structures. For example, openings can be formed at corresponding positions in the driving structure layer, and the openings can be filled with a metal material such as tungsten or copper to form the driving electrodes 11. The electrode contacts are the portion of the driving electrodes 11 in the driving substrate 10 exposed on the first surface.

[0024] The light-emitting unit 20 is located on the first surface of the driving substrate 10, and the orthographic projection of the light-emitting unit 20 on the driving substrate 10 overlaps with the electrode contacts, thereby electrically connecting the light-emitting unit 20 to the electrode contacts. The light-emitting unit 20 can be a sub-millimeter light-emitting diode (Mini LED) or a micro light-emitting diode (Micro LED). The light-emitting unit 20 includes a light-emitting epitaxial structure 23, which can be understood as a multilayer stacked structure capable of achieving efficient electroluminescence, formed by orderly growing various semiconductor single-crystal thin film layers with different functions on a single-crystal substrate 101 using epitaxial growth technology. The light-emitting epitaxial structure 23 is frustum-shaped, and the top surface area of ​​the light-emitting epitaxial structure 23 is smaller than the bottom surface area; the top surface of the light-emitting epitaxial structure 23 refers to the surface of the light-emitting epitaxial structure 23 away from the driving substrate 10, and the bottom surface of the light-emitting epitaxial structure 23 refers to the surface of the light-emitting epitaxial structure 23 close to the driving substrate 10.

[0025] The light-emitting epitaxial structure 23 includes a first semiconductor layer, a light-emitting layer, and a second semiconductor layer. The first semiconductor layer is located on one side of the driving substrate 10, and the light-emitting layer is located on the side of the first semiconductor layer away from the driving substrate 10. The second semiconductor layer is located on the side of the light-emitting layer away from the driving substrate 10. The first semiconductor layer and the second semiconductor layer have different conductivity types. Specifically, the first semiconductor layer, the light-emitting layer, and the second semiconductor layer can be an N-type semiconductor layer, a quantum well layer, and a P-type semiconductor layer, or a P-type semiconductor layer, a quantum well layer, and an N-type semiconductor layer, respectively. The N-type semiconductor layer can be an N-type GaN layer, an N-type AlGaN layer, or an N-type GaAs layer, but is not limited to these. The quantum well (MQW) layer can be an InGaN / GaN layer, an InGaN / AlGaN layer, or an AlGaN / AlGaN layer, but is not limited to these. The P-type semiconductor layer can be a P-type GaN layer, a P-type AlGaN layer, or a P-type GaAs layer, but is not limited to these.

[0026] By configuring the light-emitting epitaxial structure 23 as a frustum, the sidewalls of the light-emitting epitaxial structure 23 can be arranged in an outwardly convex arc shape in a cross-section perpendicular to the driving substrate 10. In contrast, for a frustum-shaped or truncated cone structure, its sidewalls are straight in a cross-section perpendicular to the driving substrate 10. With the same base area and the same top area, an outwardly convex arc shape on the sidewalls, compared to a straight sidewall, increases the width between opposing sidewalls. Therefore, with the same base area and the same top area, compared to a frustum-shaped or truncated cone structure, configuring the light-emitting epitaxial structure 23 as a frustum-shaped structure in this embodiment of the invention can increase the width of the active region (light-emitting layer), thereby increasing the volume of the active region, improving the potential light output power, and enhancing the light extraction efficiency of the light-emitting chip. Furthermore, compared to other spherical solutions (where the light-emitting epitaxial structure 23 is hemispherical), the top surface of the frustum-shaped light-emitting epitaxial structure 23 is a non-etchable area, protecting the top platform from etching damage. This results in the etching area (side surface area) of the frustum-shaped light-emitting epitaxial structure 23 being significantly smaller than the etching area (surface area of ​​the entire hemisphere) of the hemispherical light-emitting epitaxial structure 23 with the same bottom area. This means that when the light-emitting epitaxial structure 23 is formed by dry etching, the lattice damage area caused by plasma is smaller, which is beneficial to reduce the density of nonradiative recombination centers, improve the internal quantum efficiency, and thus improve the light extraction efficiency of the light-emitting chip.

[0027] Furthermore, by configuring the light-emitting epitaxial structure 23 as a frustum shape, its gently sloping, continuously inclined sidewall profile provides excellent "climbing" capability for subsequent thin film deposition such as the passivation layer 30 and reflective layer, ensuring the continuity and uniformity of the coating and enhancing the sidewall passivation and light reflection effects. More importantly, this invention fully utilizes the small platform at the top of the frustum-shaped MESA and its smoothly transitioning sidewalls, allowing for direct self-assembly of the microlens structure on it. This method eliminates the complex steps of additionally fabricating and aligning the bonding microlens 60 on a flat chip surface in traditional processes, achieving integrated integration of the MESA structure and the microlens 60. This self-assembled microlens 60 can more effectively collect and export light emitted from the active region, especially large-angle light, thereby significantly optimizing the chip's light extraction efficiency.

[0028] This invention provides a frustum-shaped MESA (Mesh Atomizing and Light Emitting) chip with continuously varying sidewall curves and a platform at the top. The light-emitting epitaxial structure 23 is configured as a frustum, resulting in continuously varying sidewall curves and a platform at the top. This frustum shape, occupying the same base and top area, provides a larger active area (light-emitting layer) than a frustum-shaped or prismatic structure, thereby enhancing the potential for light output power. Furthermore, its gently sloping sidewall profile provides superior "climbing" capability for subsequent thin film deposition such as the passivation layer 30 and reflective layer, ensuring the continuity and uniformity of the coating and enhancing sidewall passivation and light reflection effects. More importantly, this invention fully utilizes the small platform at the top of the frustum-shaped MESA and its smoothly transitioning sidewalls, allowing for direct self-assembly of the microlens 60 structure. This method eliminates the complex steps of fabricating and aligning the microlens 60 on a flat chip surface, as required by traditional processes, achieving integrated MESA structure and microlens 60. The self-assembled microlens 60 can more effectively collect and extract light emitted from the active region, especially large-angle light, thereby significantly optimizing the light extraction efficiency of the chip. Therefore, setting the light-emitting epitaxial structure 23 to a frustum shape can achieve better light field control and optimize the subsequent microlens 60 process, which can improve the light extraction efficiency of the light-emitting chip from multiple aspects.

[0029] Based on the above embodiments, refer to Figure 1 Optionally, the angle α between the arcuate sidewall of the light-emitting epitaxial structure 23 and the bottom surface of the light-emitting epitaxial structure 23 is less than or equal to 80° and greater than or equal to 50°.

[0030] In related technologies, the sharp transition at the connection between the sidewall and bottom of the trapezoidal structure leads to disordered light field distribution in this area, increasing absorption loss. The technical solution provided by this invention sets the light-emitting epitaxial structure 23 in a frustum shape. By adjusting the process, the connection angle between the sidewall and bottom surface of the frustum-shaped epitaxial light-emitting structure can be adjusted, and the bottom angle can be adjusted within the range of 50° to 80° as needed. Simultaneously, the continuous and gentle transition at the bottom suppresses light absorption loss, thereby further improving the light extraction efficiency of the light-emitting chip.

[0031] Based on the above embodiments, refer to Figure 1 Optionally, the light-emitting chip also includes at least one microlens 60, which is located on the side of the light-emitting unit 20 away from the driving substrate 10 and on the sidewall of the light-emitting unit 20; the microlens 60 is formed in a frustum shape based on the light-emitting epitaxial structure 23 by inorganic or organic dielectric material.

[0032] Specifically, by fully utilizing the small platform at the top of the frustum-shaped light-emitting epitaxial structure 23 and its smoothly transitioned sidewalls, the microlens 60 structure can be directly self-assembled on it, achieving integrated formation of the MESA structure and the microlens 60. This self-assembled microlens 60 can more effectively collect and extract light emitted from the active region, especially large-angle light, thereby significantly optimizing the chip's light extraction efficiency.

[0033] The microlens 60 is made of materials including, but not limited to, silicon dioxide (SiO2) or resin. Silicon dioxide has high transmittance and a suitable refractive index in the visible light band, and the microlens 60 formed from it can effectively change the propagation path of light emitted from the active layer of the chip. This structure refracts light that would otherwise be confined inside the chip due to total internal reflection into the effective light emission angle domain, thereby significantly reducing the loss of photons absorbed by electrodes or materials and directly improving the overall light extraction efficiency of the device. At the same time, by designing the curvature of the microlens 60, the emitted beam can be shaped and scattered to obtain a more uniform light field output with a wider viewing angle.

[0034] Furthermore, silicon dioxide is a fundamental dielectric material in standard planar semiconductor processes. Its thin-film deposition (such as plasma-enhanced chemical vapor deposition, PECVD), patterning (photolithography), and dry / wet etching technologies are all highly mature and cost-effective. Integrating SiO2 microlenses 60 into the light-emitting chip manufacturing process eliminates the need for unconventional materials or special equipment, enabling seamless integration with the back-end of existing chip manufacturing processes. This high degree of process compatibility not only simplifies process steps but also facilitates high-consistency, large-scale production at the wafer level, significantly reducing mass production complexity and manufacturing costs. In addition, silicon dioxide itself possesses extremely high chemical inertness, thermal stability, and density. During device operation, its physicochemical properties remain stable, making it resistant to aging, yellowing, or performance degradation, ensuring the long-term stability of optical functions. More importantly, this SiO2 microlens layer can simultaneously serve as a high-performance surface passivation layer 30, isolating it from external moisture and ion erosion, thereby enhancing the overall device's anti-aging capabilities.

[0035] Based on the above embodiments, refer to Figure 1 Optionally, the light-emitting unit 20 also includes: The first electrode 21 is located between the light-emitting epitaxial structure 23 and the driving substrate 10; the first electrode 21 is electrically connected to the electrode contacts; wherein, the material of the first electrode 21 may include metal.

[0036] Specifically, the first electrode 21 is located between the light-emitting epitaxial structure 23 and the driving substrate 10. By setting the material of the first electrode 21 to a metallic material, the first electrode 21 can be made reflective, thereby improving the light emission efficiency of the light-emitting unit 20.

[0037] In the light-emitting epitaxial structure 23, the P-type semiconductor layer is electrically connected to the positive terminal of the power supply, and the N-type semiconductor layer is electrically connected to the negative terminal of the power supply. Driven by a forward voltage, the N-type semiconductor layer continuously injects electrons into the light-emitting layer, and the P-type semiconductor layer continuously injects holes into the light-emitting layer, thereby causing the holes and electrons to recombine and emit light in the light-emitting layer. In this embodiment of the invention, the first electrode 21 can be either an anode or a cathode. The anode is connected to the positive terminal of the power supply, and the cathode is connected to the negative terminal of the power supply.

[0038] Based on the above embodiments, refer to Figure 1 Optionally, the light-emitting unit 20 also includes: The second electrode 22 is located on the side of the light-emitting epitaxial structure 23 away from the driving substrate 10; the material of the second electrode 22 may include a transparent conductive material.

[0039] The second electrode 22 has light transmittance or semi-light transmittance, which also helps to improve the light extraction efficiency of the light-emitting unit 20. The overall structure formed by the second electrode 22 and the light-emitting epitaxial structure 23 is frustum-shaped. During the fabrication of the light-emitting chip, a second electrode material layer can be formed on the side of the epitaxial layer 230 away from the driving substrate 10. Then, a patterned composite mask is formed on the side of the second electrode material layer away from the driving substrate 10. Based on the composite mask, the second electrode 22 material layer and the epitaxial layer 230 are etched to form the epitaxial light-emitting structure and the second electrode 22, thereby ensuring that the overall structure formed by the second electrode 22 and the light-emitting epitaxial structure 23 is frustum-shaped. Since the formation step of the microlens 60 is after the formation step of the second electrode 22, setting the overall structure formed by the second electrode 22 and the light-emitting epitaxial structure 23 to be frustum-shaped facilitates the self-assembly of the microlens 60 based on the deposition process. The second electrode 22 can be an anode or a cathode. Figure 1 In the structure shown, the light-emitting unit 20 includes a first electrode 21 and a second electrode 22. The first electrode 21 can be an anode and the second electrode 22 can be a cathode; alternatively, the first electrode 21 can be a cathode and the second electrode 22 can be a positive electrode. In other embodiments of the present invention, the light-emitting unit 20 may not include the second electrode 22.

[0040] Based on the above embodiments, refer to Figure 1 Optionally, the light-emitting chip may also include: The passivation layer 30 is located on the sidewall of the light-emitting unit 20 and the first surface of the driving substrate 10 not covered by the light-emitting unit 20; The electrode connection layer 40 is located on the surface of the passivation layer 30 away from the light-emitting epitaxial structure 23, the surface of the passivation layer 30 away from the driving substrate 10, and the surface of the second electrode 22 away from the light-emitting epitaxial structure 23; wherein the lower surface contour of the microlens 60 in the light-emitting chip is adapted to the upper surface contour of the electrode connection layer 40.

[0041] Specifically, the material of the passivation layer 30 includes, but is not limited to, SiO2. Covering the sidewall surface with etch damage with the passivation layer 30 can avoid leakage risks, optimize electrical performance, and significantly improve the photoelectric performance of the product. The electrode connection layer 40 is located on the surface of the passivation layer 30 away from the light-emitting epitaxial structure 23, the surface of the passivation layer 30 away from the driving substrate 10, and the surface of the second electrode 22 away from the light-emitting epitaxial structure 23. The electrode connection layer 40 is used to electrically connect the second electrode 22 to the conductive pillars 50 located on opposite sides of the light-emitting epitaxial structure 23. When the light-emitting unit 20 does not include the second electrode 22, the electrode connection layer 40 can directly contact the surface of the light-emitting epitaxial structure 23 away from the driving substrate 10. The lower surface contour of the microlens 60 in the light-emitting chip is adapted to the upper surface contour of the electrode connection layer 40, that is, the microlens 60 is formed on the upper surface of the electrode connection layer 40.

[0042] Based on the above embodiments, optionally, the light-emitting unit 20 further includes an ohmic contact layer 24 located between the first electrode 21 and the first semiconductor. The materials of the ohmic contact layer 24, the electrode connection layer 40, and the second electrode 22 all include zinc tin oxide.

[0043] This invention also provides a method for fabricating a light-emitting chip, used to prepare the light-emitting chip described in any embodiment of this invention. Figure 2 This is a flowchart of a method for fabricating a light-emitting chip according to an embodiment of the present invention, see reference. Figure 2 The methods for fabricating light-emitting chips include: S10. Provide a substrate and form an epitaxial layer on the substrate.

[0044] S20. Bond the driving substrate to the side of the epitaxial layer away from the substrate, and remove the substrate.

[0045] S30. A composite mask is formed on the side of the epitaxial layer away from the driving substrate, and the composite mask is patterned.

[0046] S40. Based on the patterned composite mask, a frustum-shaped epitaxial light-emitting structure is formed, and the top surface area of ​​the light-emitting epitaxial structure is smaller than the bottom surface area of ​​the light-emitting epitaxial structure.

[0047] The technical solution provided by this invention, based on a composite mask, forms the light-emitting epitaxial structure 23 into a frustum shape, giving the sidewalls of the light-emitting epitaxial structure 23 a continuously varying sidewall curve and a platform at the top. This frustum shape, occupying the same base area and top area, has a larger active area (light-emitting layer) volume than a frustum-shaped or prismatic structure, thereby enhancing the potential for light output power. Furthermore, its gently sloping, continuously inclined sidewall contour provides superior "climbing" capability for subsequent thin film deposition such as the passivation layer 30 and reflective layer, ensuring the continuity and uniformity of the coating and enhancing the sidewall passivation and light reflection effects. More importantly, this invention fully utilizes the small platform at the top of the frustum-shaped MESA and its smoothly transitioning sidewalls, allowing for direct self-assembly of the microlens 60 structure. This method eliminates the complex steps of additionally fabricating and aligning the microlens 60 on a flat chip surface, as required by traditional processes, achieving integrated construction of the MESA structure and the microlens 60. The self-assembled microlens 60 can more effectively collect and extract light emitted from the active region, especially large-angle light, thereby significantly optimizing the light extraction efficiency of the chip. Therefore, setting the light-emitting epitaxial structure 23 to a frustum shape can improve the light extraction efficiency of the light-emitting chip in many ways.

[0048] Optionally, step S20 involves bonding the driving substrate to the side of the epitaxial layer away from the substrate and removing the substrate, including: S210, a first bonding sublayer 211 is formed on the side of the epitaxial layer 230 away from the substrate 101, and a second bonding sublayer 212 is formed on the first surface of the driving substrate 10.

[0049] For details, please refer to Figure 3 A second bonding sublayer 212 is formed on the first surface of the driving substrate 10, as shown in the reference. Figure 4 A first bonding layer 211 is formed on the side of the epitaxial layer 230 away from the substrate 101. The materials of the first bonding layer 211 and the second bonding layer 212 can be either dielectric or metallic. In this embodiment of the invention, the materials of the first bonding layer 211 and the second bonding layer 212 are metallic, and can be used to fabricate the first electrode 21 of the light-emitting unit 20.

[0050] Further reference Figure 1 The light-emitting unit 20 also includes an ohmic contact layer 24 located between the first electrode 21 and the first semiconductor layer of the light-emitting epitaxial structure 23; Reference Figure 4 Before forming the first bonding sublayer 211 on the side of the epitaxial layer 230 away from the substrate 101, the method further includes forming an ohmic contact material layer 240 on the surface of the epitaxial layer 230 away from the substrate 101, the ohmic contact material layer 240 being used to form an ohmic contact layer 24 in a subsequent etching process.

[0051] S220, the driving substrate 10 is bonded to the epitaxial layer 230 on the side away from the substrate 101 via the first bonding sublayer 211 and the second bonding sublayer 212; the first bonding sublayer 211 and the second bonding sublayer 212 form the bonding layer 210. (Reference) Figure 5 ) S230, Remove substrate 101. (Reference) Figure 6 ) Optional, see reference Figure 7 Before forming the composite mask 70 on the side of the epitaxial layer 230 away from the driving substrate 10, the method further includes: A second electrode material layer 220 is formed on the surface of the epitaxial layer 230 away from the driving substrate 10. The second electrode material layer 220 is used to form the second electrode 22 of the light-emitting unit 20. The material of the second electrode material layer 220 includes, but is not limited to, indium tin oxide.

[0052] refer to Figure 7 and Figure 8 Step S30 involves forming a composite mask on the side of the epitaxial layer away from the driving substrate and patterning the composite mask, including: S310, a first mask layer 71 is formed on the side of the second electrode material layer 220 away from the driving substrate 10; the material of the first mask layer 71 may include SiO2.

[0053] S320, a second mask layer 72 is formed on the side of the first mask layer 71 away from the driving substrate 10. The material of the second mask layer 72 may include photoresist. The composite mask 70 includes the first mask layer 71 and the second mask layer 72. The composite mask 70 is formed on the surface of the material layer of the second electrode 22.

[0054] S330, The second mask layer 72 and the first mask layer 71 are patterned sequentially to pattern the composite mask 70.

[0055] Specifically, the second mask layer 72 can be patterned using IBE lithography, and the patterned second mask layer 72 is then thermally melted into a spherical structure.

[0056] refer to Figure 9 Step S40, based on the patterned composite mask 70, forms a frustum-shaped epitaxial light-emitting structure, and also includes: Based on the patterned composite mask 70, the second electrode material layer 220 is etched to form the second electrode 22; the overall structure formed by the second electrode 22 and the light-emitting epitaxial structure 23 is frustum-shaped.

[0057] Optional, please continue to refer to Figure 9 After step S40 forms a frustum-shaped epitaxial light-emitting structure based on the patterned composite mask, it also includes: The bonding layer 210 is etched to form the first electrode 21; the first electrode 21 is located between the light-emitting epitaxial structure 23 and the driving substrate 10.

[0058] Optionally, after etching the bonding layer 210 to form the first electrode 21, the process further includes... S50, a passivation layer 30 is formed on the sidewall of the light-emitting unit 20 and on the first surface of the driving substrate 10 not covered by the light-emitting unit 20. (Reference) Figure 10 ) S60, an electrode connection layer 40 is formed on the surface of the passivation layer 30 away from the light-emitting epitaxial structure 23, the surface of the passivation layer 30 away from the driving substrate 10, and the surface of the second electrode 22 away from the light-emitting epitaxial structure 23. (Reference) Figure 11 ) S70, conductive pillars 50 are formed on opposite sides of the light-emitting epitaxial structure 23; the electrode connection layer 40 is used to electrically connect the second electrode 22 to the conductive pillars 50 located on opposite sides of the light-emitting epitaxial structure 23. (Reference) Figure 12 ) S80. Based on the shape of the light-emitting epitaxial structure 23, a microlens 60 is formed on the side of the light-emitting unit 20 away from the driving substrate 10 and on the sidewall of the light-emitting unit 20 through a deposition process. (Reference) Figure 1 ) 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, 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 light-emitting chip, characterized in that, include: A driving substrate includes a first surface and a second surface disposed opposite to each other; the first surface includes at least one electrode contact. At least one light-emitting unit is located on the first surface of the driving substrate, and each light-emitting unit can be individually driven by the corresponding electrode contact. The light-emitting unit includes a light-emitting epitaxial structure, which is shaped like a frustum, and the top surface area of ​​the light-emitting epitaxial structure is smaller than the bottom surface area of ​​the light-emitting epitaxial structure.

2. The light-emitting chip according to claim 1, characterized in that, The angle between the arc-shaped sidewall of the light-emitting epitaxial structure and the bottom surface of the light-emitting epitaxial structure is less than or equal to 80° and greater than or equal to 50°.

3. The light-emitting chip according to claim 1, characterized in that, Also includes: At least one microlens is located on the side of the light-emitting unit away from the driving substrate and on the sidewall of the light-emitting unit; The microlens is formed in a frustum shape based on the light-emitting epitaxial structure using inorganic or organic dielectric materials.

4. The light-emitting chip according to any one of claims 1 to 3, characterized in that, The light-emitting epitaxial structure includes: The first semiconductor layer is located on one side of the driving substrate; The light-emitting layer is located on the side of the first semiconductor layer away from the driving substrate; The second semiconductor layer is located on the side of the light-emitting layer away from the driving substrate; The first semiconductor layer and the second semiconductor layer have different conductivity types.

5. The light-emitting chip according to claim 4, characterized in that, The light-emitting unit further includes: A first electrode is located between the light-emitting epitaxial structure and the driving substrate; the first electrode is electrically connected to the electrode contact; and / or... The second electrode is located on the side of the light-emitting epitaxial structure away from the driving substrate; The first electrode is made of metal, and the second electrode is made of transparent conductive material.

6. The light-emitting chip according to claim 5, characterized in that, The overall structure formed by the second electrode and the light-emitting epitaxial structure is frustum-shaped.

7. The light-emitting chip according to claim 5, characterized in that, Also includes: A passivation layer is located on the sidewall of the light-emitting unit and on the first surface of the driving substrate not covered by the light-emitting unit; An electrode connection layer is located on the surface of the passivation layer away from the light-emitting epitaxial structure, the surface of the passivation layer away from the driving substrate, and the surface of the second electrode away from the light-emitting epitaxial structure. An ohmic contact layer is located between the first electrode and the first semiconductor; the materials of the ohmic contact layer, the electrode connection layer, and the second electrode all include zinc tin oxide. The lower surface contour of the microlens in the light-emitting chip is adapted to the upper surface contour of the electrode connection layer.

8. A method for fabricating a light-emitting chip, characterized in that, For preparing the light-emitting chip according to any one of claims 1 to 7, comprising: A substrate is provided, and an epitaxial layer is formed on the substrate; The driving substrate is bonded to the epitaxial layer on the side away from the substrate, and the substrate is removed; A composite mask is formed on the side of the epitaxial layer away from the driving substrate, and the composite mask is patterned. Based on the patterned composite mask, a frustum-shaped epitaxial light-emitting structure is formed, and the top surface area of ​​the light-emitting epitaxial structure is smaller than the bottom surface area of ​​the light-emitting epitaxial structure.

9. The method for preparing a light-emitting chip according to claim 8, characterized in that, Bonding the driving substrate to the side of the epitaxial layer away from the substrate includes: A first bonding sublayer is formed on the side of the epitaxial layer away from the substrate; A second bonding layer is formed on the first surface of the driving substrate; The driving substrate is bonded to the epitaxial layer on the side away from the substrate through the first bonding sublayer and the second bonding sublayer; the first bonding sublayer and the second bonding sublayer form a bonding layer; After forming a frustum-shaped epitaxial light-emitting structure based on the patterned composite mask, the process also includes: The bonding layer is etched to form a first electrode; the first electrode is located between the light-emitting epitaxial structure and the driving substrate.

10. The method for preparing a light-emitting chip according to claim 8, characterized in that, Before forming the composite mask on the side of the epitaxial layer away from the driving substrate, the method further includes: A second electrode material layer is formed on the surface of the epitaxial layer away from the driving substrate; a composite mask is formed on the surface of the second electrode material layer away from the epitaxial layer. Based on the patterned composite mask, while forming a frustum-shaped epitaxial light-emitting structure, it also includes: A second electrode is formed; the overall structure formed by the second electrode and the light-emitting epitaxial structure is frustum-shaped.

11. The method for preparing a light-emitting chip according to claim 8, characterized in that, Also includes: Based on the shape of the light-emitting epitaxial structure, microlenses are formed on the side of the light-emitting unit away from the driving substrate and on the sidewall of the light-emitting unit by a deposition process.

Images