Light emitting structure and method of manufacturing the same

Abstract

The embodiment of the present application discloses a light emitting structure and a preparation method thereof. The light emitting structure comprises a driving substrate, a shielding layer, an epitaxial layer, and a conductive layer. The driving substrate comprises a substrate and a driving signal line layer and a pad which are sequentially arranged on the substrate, and the driving signal line layer comprises a driving signal line. The shielding layer is arranged on one side of the driving substrate and is insulated from the driving signal line. The epitaxial layer is arranged on the side of the shielding layer away from the driving substrate and is connected with the pad through a driving electrode. The epitaxial layer is insulated from the shielding layer. The conductive layer is arranged on the side of the epitaxial layer away from the shielding layer, and the conductive layer is connected with the epitaxial layer. The conductive layer comprises a first part, and the orthographic projection of the first part on the substrate does not overlap with the orthographic projection of the driving signal line on the substrate. In addition, the conductive layer comprises a second part, and the orthographic projection of the second part on the substrate is located in the orthographic projection of the shielding layer on the substrate, and the orthographic projection of the driving signal line on the substrate is located in the orthographic projection of the shielding layer on the substrate. The modulation bandwidth of the light emitting structure is improved.

Description

Technical Field

[0001] This invention relates to the field of optical communication technology, and in particular to a light-emitting structure and its preparation method. Background Technology

[0002] High-speed micron-scale light-emitting diodes (Micro LEDs) require very high modulation bandwidth when used in optical communication. The modulation bandwidth of high-speed Micro LEDs is affected not only by the active region carrier lifetime but also by junction capacitance, extended layer capacitance, encapsulation parasitics, and driving resistance. Currently, the modulation bandwidth of high-speed Micro LEDs cannot meet the demands of optical communication. Summary of the Invention

[0003] This invention provides a light-emitting structure and its preparation method to reduce the parasitic capacitance of the light-emitting structure and improve the modulation bandwidth of the light-emitting structure.

[0004] According to one aspect of the present invention, a light-emitting structure is provided, comprising: A driving substrate includes a substrate and a driving signal line layer and pads sequentially disposed on the substrate, wherein the driving signal line layer includes driving signal lines; A shielding layer is disposed on one side of the driving substrate; the shielding layer is insulated from the driving signal line; An epitaxial layer is disposed on the side of the shielding layer away from the driving substrate; the epitaxial layer is connected to the pads via driving electrodes; the epitaxial layer is insulated from the shielding layer; A conductive layer is disposed on the side of the epitaxial layer away from the shielding layer, the conductive layer is connected to the epitaxial layer, the conductive layer includes a first portion, the orthographic projection of the first portion on the substrate does not overlap with the orthographic projection of the driving signal line on the substrate; and / or, the conductive layer includes a second portion, the orthographic projection of the second portion on the substrate is located within the orthographic projection of the shielding layer on the substrate, and the orthographic projection of the driving signal line on the substrate is located within the orthographic projection of the shielding layer on the substrate.

[0005] Optionally, the drive signal line layer includes at least two metal layers; the at least two metal layers include a top metal layer, which is located on the side of any of the metal layers away from the substrate; the orthographic projection of the first portion on the substrate does not overlap with the orthographic projection of the top metal layer on the substrate; and / or, the orthographic projection of the second portion on the substrate is located within the orthographic projection of the shielding layer on the substrate, and the orthographic projection of the top metal layer on the substrate is located within the orthographic projection of the shielding layer on the substrate.

[0006] Optionally, the conductive layer includes a current spreading layer and a network connection layer; the current spreading layer is disposed on the side of the epitaxial layer away from the shielding layer, and the current spreading layer is connected to the epitaxial layer; the network connection layer is connected to the current spreading layer and is used to provide a driving voltage for the current spreading layer; the epitaxial layer includes a plurality of mesa structures, each mesa structure being connected to a pad through a driving electrode; the surface of the driving substrate has a plurality of first regions; each first region has at least one orthographic projection of the mesa structure on the driving substrate, and the edge of each first region at least partially coincides with the edge of the orthographic projection of at least one mesa structure on the driving substrate; the current spreading layer includes a plurality of island structures, the orthographic projection of the island structures on the driving substrate being located within the first region.

[0007] Optionally, the orthographic projection of the current spreading layer on the substrate does not overlap with the orthographic projection of the drive signal line on the substrate; the network connection layer includes a first sub-part, the orthographic projection of the first sub-part on the substrate does not overlap with the orthographic projection of the drive signal line on the substrate; and / or, the network connection layer includes a second sub-part, the orthographic projection of the second sub-part on the substrate being located within the orthographic projection of the shielding layer on the substrate, and the orthographic projection of the drive signal line on the substrate being located within the orthographic projection of the shielding layer on the substrate.

[0008] Optionally, the network connection layer includes multiple bridging branches and a main line, each bridging branch being connected to one of the island structures, and the main line being connected to the bridging branch; at least a portion of the main line's orthographic projection on the substrate does not overlap with the orthographic projection of the driving signal line on the substrate; or, at least a portion of the main line's orthographic projection on the substrate overlaps with the orthographic projection of the driving signal line on the substrate, and the overlapping area of ​​the main line and the driving signal line's orthographic projection on the substrate is located within the orthographic projection of the shielding layer on the substrate.

[0009] Optionally, multiple island-shaped structures are arranged in an array; the network connection layer includes multiple main lines; the main lines are disposed between adjacent island-shaped structures, and / or the main lines are disposed at the array edge of the island-shaped structures.

[0010] Optionally, the bridging branch is located on the side of the main line away from the drive substrate, and the bridging branch is at least partially connected to the main line.

[0011] Optionally, the thickness of the bridging branch is less than the thickness of the main line.

[0012] Optionally, each of the first regions coincides with the orthographic projection of one of the mesa structures onto the driving substrate; Alternatively, the first region includes at least two orthographic projections of the mesa structures onto the driving substrate, wherein the edge of each orthographic projection of the mesa structure onto the driving substrate coincides with the edge portion of the first region, and the first region is a single connected region.

[0013] According to another aspect of the present invention, a method for fabricating a light-emitting structure is provided, comprising: A conductive layer is formed on one side of the epitaxial layer; the conductive layer is connected to the epitaxial layer; A shielding layer is formed on the side of the epitaxial layer away from the conductive layer, and the epitaxial layer is insulated from the shielding layer; A driving electrode is formed on the side of the epitaxial layer away from the conductive layer. The driving electrode is insulated from the shielding layer and connected to the epitaxial layer. The driving electrode is connected to the driving substrate; the driving substrate includes a substrate and a driving signal line layer and pads sequentially disposed on the substrate, the driving signal line layer includes driving signal lines; the pads are connected to the driving electrode; the conductive layer includes a first portion, the orthographic projection of the first portion on the substrate does not overlap with the orthographic projection of the driving signal line on the substrate; and / or, the conductive layer includes a second portion, the orthographic projection of the second portion on the substrate is located within the orthographic projection of the shielding layer on the substrate, and the orthographic projection of the driving signal line on the substrate is located within the orthographic projection of the shielding layer on the substrate.

[0014] Optionally, before forming a conductive layer on one side of the epitaxial layer, the method further includes: The epitaxial layer is patterned to form multiple mesa structures; each mesa structure is connected to a pad via a driving electrode.

[0015] Optionally, a conductive layer is formed on one side of the epitaxial layer, comprising: A current spreading layer is formed on one side of the epitaxial layer; the current spreading layer is connected to the epitaxial layer. The current spreading layer is patterned to form at least one island structure; the surface of the driving substrate has a plurality of first regions; each first region has at least one orthographic projection of the mesa structure on the driving substrate, and the edge of each first region at least partially coincides with the edge of the orthographic projection of the at least one mesa structure on the driving substrate; the orthographic projection of the island structure on the driving substrate is located within the first region. A network connection layer is formed on one side of the current spreading layer, and the network connection layer is connected to the current spreading layer; the orthographic projection of the current spreading layer on the substrate does not overlap with the orthographic projection of the drive signal line on the substrate; the network connection layer includes a first sub-part, the orthographic projection of the first sub-part on the substrate does not overlap with the orthographic projection of the drive signal line on the substrate; and / or, the network connection layer includes a second sub-part, the orthographic projection of the second sub-part on the substrate is located within the orthographic projection of the shielding layer on the substrate, and the orthographic projection of the drive signal line on the substrate is located within the orthographic projection of the shielding layer on the substrate.

[0016] Optionally, the network connection layer includes multiple bridging branches and main lines; a network connection layer is formed on one side of the current extension layer, including: The main circuit is formed on one side of the island structure; at least a portion of the main circuit has an orthographic projection on the substrate that does not overlap with the orthographic projection of the drive signal line on the substrate; or, at least a portion of the main circuit has an orthographic projection on the substrate that is located within the orthographic projection of the shielding layer on the substrate, and the orthographic projection of at least a portion of the main circuit on the substrate is located within the orthographic projection of the shielding layer on the substrate. A bridging branch is formed between the island structure and the main line, and the bridging branch connects the island structure and the main line.

[0017] The technical solution of this invention reduces the parasitic capacitance between the conductive layer and the driving signal line by ensuring that the first portion of the conductive layer does not overlap with the driving signal line in the vertical direction. The overlap area between the second portion and the driving signal line in the vertical direction is shielded by a shielding layer. This reduces the parasitic capacitance of the light-emitting structure and / or reduces the impact of parasitic capacitance on the modulation bandwidth, thereby improving the modulation bandwidth of the light-emitting structure.

[0018] 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

[0019] 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.

[0020] Figure 1 This is a cross-sectional structural diagram of a light-emitting structure provided in an embodiment of the present invention; Figure 2 This is a cross-sectional structural diagram of another light-emitting structure provided in an embodiment of the present invention; Figure 3 This is a cross-sectional structural diagram of another light-emitting structure provided in an embodiment of the present invention; Figure 4 This is a partial planar structural diagram of a light-emitting structure provided in an embodiment of the present invention; Figure 5 This is a partial planar structural schematic diagram of another light-emitting structure provided in an embodiment of the present invention; Figure 6 This is a flowchart illustrating a method for fabricating a light-emitting structure according to an embodiment of the present invention. Detailed Implementation

[0021] 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.

[0022] 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.

[0023] This invention provides a light-emitting structure, which can be a co-packaged optoelectronic (CPO) structure. The light-emitting structure includes an array of MicroLEDs. When applied to optical communication, multiple arrayed MicroLEDs achieve high bandwidth in parallel. A driving signal line layer is provided on the driving substrate to provide driving signals to the MicroLEDs. The MicroLED includes an epitaxial layer and a conductive layer, with the conductive layer providing current spreading capability and driving signals to the epitaxial layer. In this application, the conductive layer and the driving signal line layer on the driving substrate can be configured to have as little overlap as possible in the vertical direction, reducing parasitic capacitance between the conductive layer and the driving signal line layer. A shielding layer is also provided between the MicroLED and the driving substrate. When the conductive layer in the MicroLED and the driving signal line layer on the driving substrate inevitably overlap in the vertical direction, a shielding layer can be provided between the overlaps. This shielding layer reduces the impact of parasitic capacitance between the MicroLED and the driving substrate on the modulation bandwidth, thereby improving the modulation bandwidth of the light-emitting structure. Specifically, Figure 1 This is a cross-sectional structural diagram of a light-emitting structure provided in an embodiment of the present invention. For example... Figure 1 As shown, the light-emitting structure includes: The driving substrate 10 includes a substrate 11 and a driving signal line layer 12 and a pad 13 sequentially disposed on the substrate 11. The driving signal line layer 12 includes driving signal lines.

[0024] A shielding layer 20 is disposed on one side of the driving substrate 10; the shielding layer 20 is insulated from the driving signal line.

[0025] The epitaxial layer 30 is disposed on the side of the shielding layer 20 away from the driving substrate 10; the epitaxial layer 30 is connected to the pad 13 through the driving electrode 40; the epitaxial layer 30 is insulated from the shielding layer 20.

[0026] A conductive layer 50 is disposed on the side of the epitaxial layer 30 away from the shielding layer 20. The conductive layer 50 is connected to the epitaxial layer 30. The conductive layer 50 includes a first portion, the orthographic projection of the first portion on the substrate 11 of which does not overlap with the orthographic projection of the driving signal line on the substrate 11; and / or, the conductive layer 50 includes a second portion, the orthographic projection of the second portion on the substrate 11 of which is located within the orthographic projection of the shielding layer 20 on the substrate 11, and the orthographic projection of the driving signal line on the substrate 11 of which is located within the orthographic projection of the shielding layer 20 on the substrate 11.

[0027] Specifically, the driving signal line layer 12 can form a driving circuit and driving signal lines. The driving signal lines are connected to the driving circuit and connected to the epitaxial layer 30 through pads 13, providing driving signals to the epitaxial layer 30. The epitaxial layer 30 may include a first semiconductor layer 301, a light-emitting layer 302, and a second semiconductor layer 303 stacked sequentially. The first semiconductor layer 301 and the second semiconductor layer 303 are semiconductor layers of different types. For example, the first semiconductor layer 301 is a P-type semiconductor layer and the second semiconductor layer 303 is an N-type semiconductor layer. Alternatively, the first semiconductor layer 301 is an N-type semiconductor layer and the second semiconductor layer 303 is a P-type semiconductor layer. When the epitaxial layer 30 is patterned to form multiple mesa structures 31, each mesa structure 31 can form a MicroLED and is connected to a corresponding pad 13 through a driving electrode 40, enabling the emission and addressing of the MicroLED in the light-emitting structure. In some embodiments, the first semiconductor layer 301 has a transparent conductive layer on the side away from the light-emitting layer 302, serving as a current spreading layer on one side of the first semiconductor layer 301 to improve the current spreading capability of the MicroLED. In this case, the mesa structure can be connected to the pad 13 via the transparent conductive layer and the driving electrode 40. Exemplarily, the driving electrode 40 can be electrically connected to the pad 13 through hybrid bonding. The material of the pad 13 can be copper. The dimensions of the driving electrode 40 and the pad 13 can be unequal; when the driving electrode 40 and the pad 13 are hybrid bonded, alignment tolerance and edge parasitic capacitance can be reduced simultaneously. For example, as... Figure 1 As shown, the size of the driving electrode 40 can be smaller than the size of the pad 13. In other embodiments, the size of the driving electrode 40 can also be larger than the size of the pad 13, which is not limited here.

[0028] A shielding layer 20 is disposed between the epitaxial layer 30 and the driving substrate 10, and is insulated from the epitaxial layer 30 through a first insulating layer and from the driving substrate 10 through a second insulating layer. The shielding layer 20 can be an entire film layer, providing maximum shielding for the conductive layers on both sides. The shielding layer 20 is insulated from the driving electrode 40, preventing short-circuit connections between the shielding layer 20 and the epitaxial layer 30 or the driving substrate 10 through the driving electrode 40. For example, as... Figure 1 As shown, the shielding layer 20 has a via on the underside of the epitaxial layer 30 near the driving substrate 10. The size of the via is larger than the size of the driving electrode 40, so that the driving electrode 40 and the shielding layer 20 are insulated from each other by an insulating layer. The material of the shielding layer 20 can be metal. A portion of the surface of the shielding layer 20 near the driving substrate 10 is exposed for grounding, so that the shielding layer 20 can shield the electric field between the conductive layer on the epitaxial layer 30 side and the driving substrate 10, reducing the impact of parasitic capacitance on the modulation bandwidth. For example, a via is provided on the second insulating layer between the shielding layer 20 and the driving substrate 10, through which the shielding layer 20 is grounded.

[0029] The conductive layer 50 is connected to the epitaxial layer 30 and provides current spreading capability and driving signal to the epitaxial layer 30. At least a portion of the conductive layer 50 is a transparent conductive layer, used to provide current spreading capability to the epitaxial layer 30. For example, the material of the transparent conductive layer can be ITO. The conductive layer 50 may also include a metal layer for providing driving signal to the epitaxial layer 30 through the transparent conductive layer. The conductive layer 50 may include a first portion that does not overlap with the driving signal line on the driving substrate 10 in the vertical direction, avoiding the formation of parasitic capacitance between the first portion and the driving signal line. The conductive layer 50 may also include a second portion that overlaps with the driving signal line in the vertical direction, and this overlapping portion is shielded by the shielding layer 20. This reduces the impact of parasitic capacitance between the second portion and the driving signal line on the modulation bandwidth. Therefore, in the light-emitting structure, the overlap area between the conductive layer 50 and the driving signal line in the vertical direction can be minimized as much as possible according to the principle of minimizing the overlap area of ​​the conductive layer 50 and the driving signal line in the vertical direction. When the conductive layer 50 and the driving signal line inevitably overlap in the vertical direction, this overlap area is shielded by the shielding layer 20. This reduces the parasitic capacitance of the light-emitting structure and / or reduces the impact of parasitic capacitance on the modulation bandwidth, thereby improving the modulation bandwidth of the light-emitting structure.

[0030] It should be noted that when the shielding layer 20 is a whole film layer, the first part of the conductive layer 50 can also overlap with the shielding layer 20 in the vertical direction, so that the shielding layer 20 shields the first part of the conductive layer 50, further reducing the impact of the parasitic capacitance between the conductive layer 50 and the driving signal line on the modulation bandwidth.

[0031] The technical solution of this embodiment reduces the parasitic capacitance between the conductive layer and the driving signal line by ensuring that the first portion of the conductive layer does not overlap with the driving signal line in the vertical direction. The overlap area between the second portion and the driving signal line in the vertical direction is shielded by a shielding layer. This reduces the parasitic capacitance of the light-emitting structure and / or reduces the impact of parasitic capacitance on the modulation bandwidth, thereby improving the modulation bandwidth of the light-emitting structure.

[0032] Figure 2 This is a cross-sectional schematic diagram of another light-emitting structure provided in an embodiment of the present invention. For example... Figure 2 As shown, the drive signal line layer 12 includes at least two metal layers; the at least two metal layers include a top metal layer 121, which is located on the side of any metal layer away from the substrate 11; the orthographic projection of the first portion 510 on the substrate 11 does not overlap with the orthographic projection of the top metal layer 121 on the substrate 11; and / or, the orthographic projection of the second portion 520 on the substrate 11 is located within the orthographic projection of the shielding layer 20 on the substrate 11, and the orthographic projection of the top metal layer 121 on the substrate 11 is located within the orthographic projection of the shielding layer 20 on the substrate 11.

[0033] Specifically, the driving signal line layer 12 may include multiple metal layers disposed on the substrate 11, with an insulating layer between adjacent metal layers to form a driving circuit. The driving signal line may be disposed on the metal layer closest to the epitaxial layer, that is, the driving signal line is disposed on the top metal layer 121 of the driving electrode. For example, the driving signal line may be a high-speed clock signal line, an analog sensitive line, and a high-speed driving output line, etc. The top metal layer 121 is the metal layer closest to the epitaxial layer 30, that is, the metal layer closest to the conductive layer 50. When a parasitic capacitance is formed between the driving signal line layer 12 and the conductive layer 50, the parasitic capacitance between the top metal layer 121 and the conductive layer 50 is the largest. At this time, the first part 510 and the top metal layer 121 are not overlapped in the vertical direction. According to the principle of minimizing the overlap area between the conductive layer 50 and the top metal layer 121 in the vertical direction, the parasitic capacitance between the conductive layer and the top metal layer 121 can be minimized as much as possible, thereby improving the modulation bandwidth of the light-emitting structure. Simultaneously, when the second part 520 overlaps with the top metal layer 121 in the vertical direction, the overlapping area can be shielded by the shielding layer 20, reducing the impact of parasitic capacitance on the modulation bandwidth and further improving the modulation bandwidth of the light-emitting structure.

[0034] It should be noted that when the conductive layer 50 is used to provide current spreading capability for the epitaxial layer 30, the conductive layer 50 overlaps with the driving electrode 40 in the vertical direction. The shielding layer 20 is insulated from the driving electrode 40, that is, there is a gap between the shielding layer 20 and the driving electrode 40. Therefore, the shielding layer 20 does not overlap with the conductive layer 50 in the vertical direction around the driving electrode 40. The top metal layer 121 has no conductive structure around the driving electrode 40, avoiding direct overlap between the top metal layer 121 and the conductive layer 50 in the vertical direction.

[0035] Figure 3 This is a cross-sectional schematic diagram of another light-emitting structure provided in an embodiment of the present invention. Figure 4 This is a partial planar structural diagram of a light-emitting structure provided in an embodiment of the present invention. (See diagram below.) Figure 3 and Figure 4As shown, the conductive layer 50 includes a current spreading layer 51 and a network connection layer 52; the current spreading layer 51 is disposed on the side of the epitaxial layer 30 away from the shielding layer 20, and the current spreading layer 51 is connected to the epitaxial layer 30; the network connection layer 52 is connected to the current spreading layer 51 and is used to provide a driving voltage for the current spreading layer 51; the epitaxial layer 30 includes a plurality of mesa structures 31, each mesa structure 31 being connected to a pad 13 through a driving electrode 40; the surface of the driving substrate 10 has a plurality of first regions 32; each first region 32 has at least one orthographic projection of a mesa structure 31 on the driving substrate 10, and the edge of each first region 32 at least partially coincides with the edge of the orthographic projection of at least one mesa structure 31 on the driving substrate 10; the current spreading layer 51 includes a plurality of island structures 511, and the orthographic projection of the island structures 511 on the driving substrate 10 is located within the first region 32.

[0036] Specifically, the driving substrate 10 may include a clearance region and a functional signal region. A first region 32 may be disposed in the clearance region, and the driving signal line may be disposed in the functional signal region. The driving substrate 10 has multiple first regions 32, which can be configured according to the mesa structure 31. For example, such as... Figure 4 As shown, the first region 32 can be the region of the orthographic projection of a platform structure 31 onto the driving substrate 10. Figure 5 This is a partial planar structural schematic diagram of another light-emitting structure provided in an embodiment of the present invention. (See attached diagram.) Figure 5 As shown, in other embodiments, the first region 32 can be the region formed by the orthographic projection of multiple mesa structures 31 onto the driving substrate 10. When the epitaxial layer 30 includes multiple mesa structures 31, each mesa structure 31 can form a MicroLED. The number of driving electrodes 40, the number of pads 13, and the number of driving circuits can all be equal to the number of mesa structures 31, so that each mesa structure 31 can be connected to a driving circuit through a driving electrode 40, a pad 13, and a driving circuit, thereby enabling the addressing of the MicroLED in the light-emitting structure.

[0037] A current spreading layer 51 is disposed on the surface of the epitaxial layer 30 and is in contact with the second semiconductor layer 302 to provide current spreading capability for the epitaxial layer 30. The current spreading layer 51 is a transparent conductive layer, such as ITO. A network connection layer 52 overlaps with the current spreading layer 51 and provides a driving signal to the epitaxial layer 30 through the current spreading layer 51, while reducing the influence of the network connection layer 52 on light. For example, the network connection layer 52 can be a metal network. If the orthogonal projection of the island-shaped structures 511 on the current spreading layer 51 onto the driving substrate 10 is located within the first region 32, then the current spreading layer 51 can be connected to each mesa structure 31 to provide better current spreading capability for the mesa structure 31 and ensure the brightness uniformity of the light-emitting structure. The current spreading layer 51 includes multiple island-shaped structures 511, with gaps between adjacent island-shaped structures 511. When an electrical signal is present on the current spreading layer 51, multiple independent island structures 511 can segment the high-frequency equipotential surface of the current spreading layer 51 into local segments, thereby shortening the continuous path of the high-frequency equipotential surface. Simultaneously, compared to a single layer of current spreading layer 51, the area of ​​the current spreading layer 51 is reduced. By insulating the current spreading layer 51 from the driving signal line, the overlap area between the island structures 511 and the driving signal line in the vertical direction is reduced, thereby lowering the parasitic capacitance formed by the island structures 511 and the driving signal line. While ensuring the current spreading capability of the mesa structure 31, the modulation bandwidth of the light-emitting structure is improved. For example, as... Figure 4 As shown, when the first region 32 has a mesa structure 31 projected onto the driving substrate 10, the island structure 511 can cover the mesa structure 31. In this case, the island structure 511 can provide current spreading capability for one mesa structure 31. Simultaneously, the current spreading layer 51 is not covered between adjacent mesa structures 31, reducing the parasitic capacitance between the current spreading layer 51 and the conductive structures on the driving substrate 10, thus improving the modulation bandwidth of the light-emitting structure. Alternatively, as... Figure 5 As shown, when the first region 32 has 2×2 mesa structures 31, the 2×2 mesa structures 31 form a superpixel. Each island structure 511 can cover one superpixel. At this time, the island structure 511 can provide current spreading capability for the four mesa structures 31. At the same time, the current spreading layer 51 does not cover between superpixels, reducing the parasitic capacitance between the current spreading layer 51 and the driving signal line, and improving the modulation bandwidth of the light-emitting structure. In other embodiments, the superpixel can also be composed of 4×4 mesa structures 31, which is not limited here. Compared with the technical solution where the current spreading layer is a whole layer structure, the overlap area between the current spreading layer 51 and the driving signal line in the vertical direction provided by the embodiment of the present invention is reduced by at least 30%.

[0038] In some embodiments, each first region 32 coincides with the orthographic projection of a mesa structure 31 onto the driving substrate 10; or, the first region 32 includes the orthographic projections of at least two mesa structures 31 onto the driving substrate 10, the edges of the orthographic projections of each mesa structure 31 onto the driving substrate 10 coincide with the edge portion of the first region 32, and the first region 32 is a single connected region.

[0039] For details, please refer to Figure 4 Each first region 32 coincides with the orthographic projection of a mesa structure 31 onto the driving substrate 10. In this case, each first region 32 corresponds to the orthographic projection region of a mesa structure 31 onto the driving substrate 10. When the orthographic projection of the island structure 511 onto the driving substrate 10 is located within the first region 32, each island structure 511 can be located within the mesa structure 31. While ensuring current spreading capability and brightness uniformity for the mesa structure 31, the overlap area between the current spreading layer 51 and the driving signal lines on the driving substrate 10 in the vertical direction is minimized as much as possible, thereby minimizing the parasitic capacitance between them and improving the modulation bandwidth of the light-emitting structure. For example, if the pitch between the mesa structures 31 is 50 μm to 100 μm, then the distance between adjacent island structures 511 is greater than or equal to 50 μm to 100 μm.

[0040] refer to Figure 5 The first region 32 includes the orthographic projections of at least two mesa structures 31 onto the driving substrate 10. The edge of the orthographic projection of each mesa structure 31 onto the driving substrate 10 coincides with the edge of the first region 32, and the first region 32 is a single-connected region. In this case, the first region 32 is the area enclosed by the orthographic projections of multiple mesa structures 31 onto the driving substrate 10. This also ensures that the current spreading layer 51 provides current spreading capability and brightness uniformity to the mesa structures 31 while reducing the parasitic capacitance between the current spreading layer 51 and the conductive structures on the driving substrate 10.

[0041] Continue to refer to Figure 3 and Figure 4 The orthographic projection of the current spreading layer 51 on the substrate 11 does not overlap with the orthographic projection of the drive signal line on the substrate 11; the network connection layer 52 includes a first sub-part, the orthographic projection of the first sub-part on the substrate 11 does not overlap with the orthographic projection of the drive signal line on the substrate 11; and / or, the network connection layer 52 includes a second sub-part, the orthographic projection of the second sub-part on the substrate 11 is located within the orthographic projection of the shielding layer 20 on the substrate 11, and the orthographic projection of the drive signal line on the substrate 11 is located within the orthographic projection of the shielding layer 20 on the substrate 11.

[0042] Specifically, the island-shaped structures 511 can be arranged in an array. Based on the principle of minimizing the overlap area between the conductive layer 50 and the driving signal line in the vertical direction, the island-shaped structures 511 and the driving signal line can be arranged without overlap in the vertical direction, reducing the parasitic capacitance between the conductive layer 50 and the driving signal line. Simultaneously, when the network extension of the network connection layer 52 inevitably overlaps with the driving signal line in the vertical direction, a shielding layer 20 can be used to shield the overlap area, reducing the impact of the parasitic capacitance between the network connection layer 52 and the driving signal line on the modulation bandwidth and improving the modulation bandwidth of the light-emitting structure.

[0043] Continue to refer to Figure 3 and Figure 4 The network connection layer 52 includes multiple bridging branches 521 and main lines 522. Each bridging branch 521 is connected to an island structure 511, and the main lines 522 are connected to the bridging branches 521. At least a portion of the orthographic projection of the main line 522 on the substrate 11 does not overlap with the orthographic projection of the drive signal line on the substrate 11; or, at least a portion of the orthographic projection of the main line 522 on the substrate 11 overlaps with the orthographic projection of the drive signal line on the substrate 11, and the overlapping area of ​​the orthographic projection of the main line 522 and the drive signal line on the substrate 11 is located within the orthographic projection of the shielding layer 20 on the substrate 11.

[0044] Specifically, the bridging branch 521 can be a short bridge with a narrow neck, facilitating the electrical extension of the island structure 511. The main line 522 can be a bus line, used to combine currents from multiple island structures 511. When the island structure 511 is connected to the main line 522 through the bridging branch 521, the main line 522 can simultaneously provide driving signals to multiple island structures 511, which is beneficial for achieving consistency in the current injection path, thereby improving the current uniformity of different island structures 511 and enhancing the brightness uniformity of the light-emitting structure. When the network connection layer 52 and the driving signal line inevitably overlap in the vertical direction, the bridging branch 521 can be configured to overlap with the driving signal line in the vertical direction, while the main line 522 and the driving signal line can be configured not to overlap in the vertical direction. Alternatively, when the main line 522 and the driving signal line overlap in the vertical direction, the overlapping area can be shielded by the shielding layer 20. When the extension distance of the bridging branch 521 is relatively short, it can avoid long-distance parallel overlap between the drive signal line and the network connection layer 52 in the vertical direction, and minimize the parasitic capacitance between the drive signal line and the network connection layer 52.

[0045] Continue to refer to Figure 4 Multiple island-shaped structures 511 are arranged in an array; the network connection layer 52 includes multiple main lines 522; the main lines 522 are located between adjacent island-shaped structures 511, and / or the main lines 522 are located at the array edge of the island-shaped structures 511.

[0046] Specifically, when the island structures 511 are arranged in an array, the main lines 522 can include multiple lines. Each main line 522 can be positioned between two adjacent rows of island structures 511 along the row direction, so that each main line 522 carries the driving signal of at least one row of island structures 511. Alternatively, each main line 522 can be positioned between two adjacent columns of island structures 511 along the column direction, so that each main line 522 carries the driving signal of at least one column of island structures 511. This realizes the network structure of the network connection layer 52 and improves the current uniformity of different island structures 511.

[0047] Continue to refer to Figure 3 The bridging branch 521 is located on the side of the main line 522 away from the drive substrate 10, and the bridging branch 521 is at least partially connected to the main line 522.

[0048] Specifically, the bridging branch 521 and the main line 522 can be layered, in which case the network connection layer 52 is a layered network. When forming the network connection layer 52, the main line 522 can first be formed by depositing metal and patterning it. In some embodiments, the thickness of the main line 522 is greater than the thickness of the bridging branch 521, which can reduce the equivalent resistance on the main line 522, thereby reducing the voltage difference on different island structures 511. Then, the bridging branch 521 is formed by depositing and patterning, so that the bridging branch 521 simultaneously connects to the main line 522 when connected to the island structure 511. For example, the bridging branch 521 can be formed using a liftoff process, allowing the bridging branch 521 to simultaneously connect to both the island structure 511 and the main line 522.

[0049] For example, in the prior art, when the current spreading layer of the light-emitting structure is a monolithic structure and the network connection layer is a continuous co-layer network structure, the parasitic capacitance between the current spreading layer and the network connection layer and the driving substrate averages 18 fF to 47 fF per mesa structure. In this application, by setting the current spreading layer as an island structure and the network connection layer including bridging branches and main lines, and minimizing the overlap area between the top metal layer on the driving substrate and the island structure and network connection layer in the vertical direction, the parasitic capacitance between the current spreading layer and the network connection layer and the driving substrate averages 8 fF to 22 fF per mesa structure. If the intrinsic junction capacitance of the epitaxial layer is in the range of 35 fF to 60 fF, the light-emitting structure can bring a bandwidth gain of approximately 15% to 30% in the driving RC dominant frequency band.

[0050] This invention also provides a method for fabricating a light-emitting structure, used to fabricate the light-emitting structure provided in any embodiment of this invention. Figure 6 This is a schematic flowchart illustrating a method for fabricating a light-emitting structure according to an embodiment of the present invention. Figure 6As shown, the light emission method includes: S110. A conductive layer is formed on one side of the epitaxial layer; the conductive layer is connected to the epitaxial layer.

[0051] S120. A shielding layer is formed on the side of the epitaxial layer away from the conductive layer, and the epitaxial layer is insulated from the shielding layer.

[0052] Specifically, a first insulating layer exists between the epitaxial layer and the shielding layer. Before forming the shielding layer on the side of the epitaxial layer away from the conductive layer, the first insulating layer can be formed on that side. Then, the shielding layer is formed on the first insulating layer. The shielding layer has a via at the driving electrode to prevent short circuits between the shielding layer and the driving electrode during subsequent electrode formation. After forming the shielding layer, a second insulating layer can be formed on the side of the shielding layer away from the epitaxial layer to achieve insulation between the shielding layer and the driving substrate. Additionally, a via can be provided on the second insulating layer to expose the surface of the shielding layer. The shielding layer can be grounded through this via.

[0053] S130. A driving electrode is formed on the side of the epitaxial layer away from the conductive layer. The driving electrode is insulated from the shielding layer and connected to the epitaxial layer.

[0054] Specifically, the epitaxial layer includes a first semiconductor layer, a light-emitting layer, and a second semiconductor layer stacked sequentially. When the first semiconductor layer has a transparent conductive layer as a current spreading layer on the side away from the light-emitting layer, the transparent conductive layer can be formed first on the surface of the first semiconductor layer. Then, an insulating layer and a shielding layer are formed sequentially. After the driving electrode is formed, the driving electrode can be connected to the transparent semiconductor layer.

[0055] S140. Connect the driving electrode to the driving substrate; the driving substrate includes a substrate and a driving signal line layer and a pad sequentially disposed on the substrate, the driving signal line layer includes driving signal lines; the pads are connected to the driving electrode; the conductive layer includes a first portion, the orthographic projection of the first portion on the substrate does not overlap with the orthographic projection of the driving signal line on the substrate; and / or, the conductive layer includes a second portion, the orthographic projection of the second portion on the substrate is located within the orthographic projection of the shielding layer on the substrate, and the orthographic projection of the driving signal line on the substrate is located within the orthographic projection of the shielding layer on the substrate.

[0056] The technical solution of this embodiment reduces the parasitic capacitance between the conductive layer and the driving signal line by ensuring that the first portion of the conductive layer does not overlap with the driving signal line in the vertical direction. The overlap area between the second portion and the driving signal line in the vertical direction is shielded by a shielding layer. This reduces the parasitic capacitance of the light-emitting structure and / or reduces the impact of parasitic capacitance on the modulation bandwidth, thereby improving the modulation bandwidth of the light-emitting structure.

[0057] In some embodiments, before forming a conductive layer on one side of the epitaxial layer, the method further includes: The epitaxial layer is patterned to form multiple mesa structures; each mesa structure is connected to a pad through a driving electrode.

[0058] In some embodiments, a conductive layer is formed on one side of the epitaxial layer, including: A current spreading layer is formed on one side of the epitaxial layer; the current spreading layer is connected to the epitaxial layer.

[0059] The current spreading layer is patterned to form at least one island structure; the surface of the driving substrate has a plurality of first regions; each first region has at least one orthographic projection of a mesa structure on the driving substrate, and the edge of each first region at least partially coincides with the edge of the orthographic projection of the at least one mesa structure on the driving substrate; the orthographic projection of the island structure on the driving substrate is located within the first region.

[0060] A network connection layer is formed on one side of the current spreading layer, and the network connection layer is connected to the current spreading layer; the orthographic projection of the current spreading layer on the substrate does not overlap with the orthographic projection of the drive signal line on the substrate; the network connection layer includes a first sub-part, the orthographic projection of the first sub-part on the substrate does not overlap with the orthographic projection of the drive signal line on the substrate; and / or, the network connection layer includes a second sub-part, the orthographic projection of the second sub-part on the substrate is located within the orthographic projection of the shielding layer on the substrate, and the orthographic projection of the drive signal line on the substrate is located within the orthographic projection of the shielding layer on the substrate.

[0061] Specifically, after forming the island structure, an insulating layer can be formed on one side of the island structure. Then, a network connection layer is formed on the insulating layer and patterned. This connects the network connection layer to the current spreading layer while avoiding connection to the epitaxial layer.

[0062] In some embodiments, the network connectivity layer includes multiple bridging branches and a main line; a network connectivity layer is formed on one side of the current spreading layer, including: A main circuit is formed on one side of the island structure; the orthographic projection of at least a portion of the main circuit on the substrate does not overlap with the orthographic projection of the drive signal line on the substrate; or, the orthographic projection of at least a portion of the main circuit on the substrate is within the orthographic projection of the shielding layer on the substrate, and the orthographic projection of at least a portion of the main circuit on the substrate is within the orthographic projection of the shielding layer on the substrate.

[0063] A bridging branch road is formed between the island structure and the main line, and the bridging branch road connects the island structure and the main line.

[0064] In some embodiments, after forming the network connection layer, the light-emitting structure can be encapsulated so that the encapsulation layer covers the current spreading layer and the network connection layer, thereby improving the lifetime of the light-emitting structure.

[0065] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0066] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A light-emitting structure, characterized in that, include: A driving substrate includes a substrate and a driving signal line layer and pads sequentially disposed on the substrate, wherein the driving signal line layer includes driving signal lines; A shielding layer is disposed on one side of the driving substrate; the shielding layer is insulated from the driving signal line; An epitaxial layer is disposed on the side of the shielding layer away from the driving substrate; the epitaxial layer is connected to the pads via driving electrodes; the epitaxial layer is insulated from the shielding layer; A conductive layer is disposed on the side of the epitaxial layer away from the shielding layer. The conductive layer is connected to the epitaxial layer. The conductive layer includes a first portion, and the orthographic projection of the first portion on the substrate does not overlap with the orthographic projection of the driving signal line on the substrate. And / or, the conductive layer includes a second portion, the orthographic projection of the second portion on the substrate being located within the orthographic projection of the shielding layer on the substrate, and the orthographic projection of the drive signal line on the substrate being located within the orthographic projection of the shielding layer on the substrate.

2. The light-emitting structure according to claim 1, characterized in that, The drive signal line layer includes at least two metal layers; the at least two metal layers include a top metal layer, which is located on the side of any of the metal layers away from the substrate; the orthographic projection of the first portion on the substrate does not overlap with the orthographic projection of the top metal layer on the substrate; And / or, the orthographic projection of the second portion on the substrate lies within the orthographic projection of the shielding layer on the substrate, and the orthographic projection of the top metal layer on the substrate lies within the orthographic projection of the shielding layer on the substrate.

3. The light-emitting structure according to claim 1 or 2, characterized in that, The conductive layer includes a current spreading layer and a network connection layer; the current spreading layer is disposed on the side of the epitaxial layer away from the shielding layer, and the current spreading layer is connected to the epitaxial layer; The network connection layer is connected to the current spreading layer and is used to provide a driving voltage for the current spreading layer; the epitaxial layer includes a plurality of mesa structures, each mesa structure being connected to a pad through a driving electrode; the surface of the driving substrate has a plurality of first regions; each first region has at least one orthogonal projection of the mesa structure on the driving substrate, and the edge of each first region at least partially coincides with the edge of the orthogonal projection of at least one mesa structure on the driving substrate; The current spreading layer includes multiple island-shaped structures, and the orthographic projection of the island-shaped structures on the driving substrate is located within the first region.

4. The light-emitting structure according to claim 3, characterized in that, The orthographic projection of the current spreading layer on the substrate does not overlap with the orthographic projection of the driving signal line on the substrate; The network connection layer includes a first sub-part, wherein the orthographic projection of the first sub-part on the substrate does not overlap with the orthographic projection of the drive signal line on the substrate; And / or, the network connection layer includes a second sub-part, the orthographic projection of the second sub-part on the substrate being located within the orthographic projection of the shielding layer on the substrate, and the orthographic projection of the drive signal line on the substrate being located within the orthographic projection of the shielding layer on the substrate.

5. The light-emitting structure according to claim 3, characterized in that, The network connection layer includes multiple bridging branches and main lines. Each bridging branch is connected to one of the island structures, and the main lines are connected to the bridging branches. At least a portion of the main lines have no overlap between their orthographic projection on the substrate and the orthographic projection of the drive signal lines on the substrate. Alternatively, at least a portion of the main circuit's orthographic projection on the substrate overlaps with the orthographic projection of the drive signal line on the substrate, and the overlapping area of ​​the orthographic projections of the main circuit and the drive signal line on the substrate is located within the orthographic projection of the shielding layer on the substrate.

6. The light-emitting structure according to claim 5, characterized in that, Multiple island-shaped structures are arranged in an array; the network connection layer includes multiple main lines; the main lines are disposed between adjacent island-shaped structures, and / or the main lines are disposed at the array edges of the island-shaped structures.

7. The light-emitting structure according to claim 5, characterized in that, The bridging branch is located on the side of the main line away from the drive substrate, and the bridging branch is at least partially connected to the main line.

8. The light-emitting structure according to claim 7, characterized in that, The thickness of the bridging branch is less than the thickness of the main line.

9. The light-emitting structure according to claim 4, characterized in that, Each of the first regions coincides with the orthographic projection of one of the mezzanine structures onto the driving substrate; Alternatively, the first region includes at least two orthographic projections of the mesa structures onto the driving substrate, wherein the edge of each orthographic projection of the mesa structure onto the driving substrate coincides with the edge portion of the first region, and the first region is a single connected region.

10. A method for fabricating a light-emitting structure, characterized in that, include: A conductive layer is formed on one side of the epitaxial layer; The conductive layer is connected to the epitaxial layer; A shielding layer is formed on the side of the epitaxial layer away from the conductive layer, and the epitaxial layer is insulated from the shielding layer; A driving electrode is formed on the side of the epitaxial layer away from the conductive layer. The driving electrode is insulated from the shielding layer and connected to the epitaxial layer. The driving electrode is connected to the driving substrate; the driving substrate includes a substrate and a driving signal line layer and a pad sequentially disposed on the substrate, the driving signal line layer includes driving signal lines; the pads are connected to the driving electrode; the conductive layer includes a first portion, the orthographic projection of the first portion on the substrate does not overlap with the orthographic projection of the driving signal line on the substrate; And / or, the conductive layer includes a second portion, the orthographic projection of the second portion on the substrate being located within the orthographic projection of the shielding layer on the substrate, and the orthographic projection of the drive signal line on the substrate being located within the orthographic projection of the shielding layer on the substrate.

11. The method for fabricating the light-emitting structure according to claim 10, characterized in that, Before forming a conductive layer on one side of the epitaxial layer, the following is also included: The epitaxial layer is patterned to form multiple mesa structures; each mesa structure is connected to a pad via a driving electrode.

12. The method for fabricating the light-emitting structure according to claim 11, characterized in that, A conductive layer is formed on one side of the epitaxial layer, including: A current spreading layer is formed on one side of the epitaxial layer; the current spreading layer is connected to the epitaxial layer. The current spreading layer is patterned to form at least one island structure; the surface of the driving substrate has a plurality of first regions; each first region has at least one orthographic projection of the mesa structure on the driving substrate, and the edge of each first region at least partially coincides with the edge of the orthographic projection of the at least one mesa structure on the driving substrate; the orthographic projection of the island structure on the driving substrate is located within the first region. A network connection layer is formed on one side of the current spreading layer, and the network connection layer is connected to the current spreading layer; the orthographic projection of the current spreading layer on the substrate does not overlap with the orthographic projection of the drive signal line on the substrate; the network connection layer includes a first sub-part, the orthographic projection of the first sub-part on the substrate does not overlap with the orthographic projection of the drive signal line on the substrate; and / or, the network connection layer includes a second sub-part, the orthographic projection of the second sub-part on the substrate is located within the orthographic projection of the shielding layer on the substrate, and the orthographic projection of the drive signal line on the substrate is located within the orthographic projection of the shielding layer on the substrate.

13. The method for fabricating the light-emitting structure according to claim 12, characterized in that, The network connection layer includes multiple bridging branches and main lines; A network connection layer is formed on one side of the current spreading layer, including: The main circuit is formed on one side of the island structure; at least a portion of the main circuit has an orthographic projection on the substrate that does not overlap with the orthographic projection of the drive signal line on the substrate; or, at least a portion of the main circuit has an orthographic projection on the substrate that is located within the orthographic projection of the shielding layer on the substrate, and the orthographic projection of at least a portion of the main circuit on the substrate is located within the orthographic projection of the shielding layer on the substrate. A bridging branch is formed between the island structure and the main line, and the bridging branch connects the island structure and the main line.

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