Light emitting diode and light emitting device

Abstract

The invention relates to the technical field of semiconductor manufacturing, in particular to a light-emitting diode which comprises a first semiconductor layer, a light-emitting layer, a second semiconductor layer, a plurality of protrusion structures and a reflection structure. The first semiconductor layer is provided with an upper surface and a lower surface which are opposite to each other, the light-emitting layer is located on the upper surface of the first semiconductor layer, the second semiconductor layer is located on the light-emitting layer, the plurality of convex structures are distributed on the lower surface of the first semiconductor layer, the reflection structure covers the plurality of convex structures at intervals, and the reflection structure is provided with a plurality of light-emitting holes. The light outlet holes are exposed out of the protruding structures, and at least one protruding structure exists between every two adjacent light outlet holes. By means of the arrangement of the reflection structure, light can be emitted from the light outlet hole, small-angle vertical concentrated light emitting is further formed, and the requirement of the light emitting diode for small-angle vertical concentrated light emitting is met.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing technology, and in particular to a light emitting diode and a light emitting device. Background Art

[0002] Light Emitting Diode (LED) is a semiconductor light-emitting element, usually made of semiconductors such as GaN, GaAs, GaP, GaAsP, etc., and its core is a PN junction with light-emitting characteristics. LED has the advantages of high luminous intensity, high efficiency, small size, and long service life, and is considered to be one of the most promising light sources at present. LED has been widely used in lighting, monitoring and command, high-definition broadcasting, high-end cinemas, office displays, conference interaction, virtual reality and other fields.

[0003] In recent years, Micro LED chips, as the ultimate display, have gradually become commercialized. In car displays and watch displays, the commercialization requirements for Micro LED chips are: the chip must emit light at a small angle perpendicular to the chip plane. At present, due to the advantages of GaN materials, Micro LED chips mostly use GaN materials as epitaxy, so their light-emitting surface is the GaN surface, but the refractive index of GaN material and air is very different, resulting in a large total reflection angle, and most of the light will be confined to the GaN layer (epitaxial) and cannot be emitted. In order to overcome this problem, the surface of the GaN layer is usually patterned. However, the light emission direction of the patterned GaN layer is random, and it still cannot meet the commercial requirements of small-angle vertical concentrated light emission. Therefore, how to ensure that Micro LED chips can achieve the effect of small-angle vertical concentrated light emission has become one of the technical problems that need to be solved urgently in this field.

[0004] It should be noted that the information disclosed in this background technology section is only intended to increase the understanding of the overall background of the present invention, and should not be regarded as admitting or suggesting in any form that the information constitutes the prior art known to those skilled in the art. Summary of the invention

[0005] The present invention provides a light emitting diode, which comprises a first semiconductor layer, a light emitting layer, a second semiconductor layer, a plurality of protruding structures and a reflective structure.

[0006] The first semiconductor layer has an upper surface and a lower surface relative to each other. The light-emitting layer is located on the upper surface of the first semiconductor layer. The second semiconductor layer is located above the light-emitting layer. A plurality of protrusion structures are distributed on the lower surface of the first semiconductor layer. The reflective structure covers the plurality of protrusion structures at intervals. The reflective structure has a plurality of light-emitting holes, and the protrusion structures are exposed in the light-emitting holes. There is at least one protrusion structure between two adjacent light-emitting holes. By setting the reflective structure with interval coverage, light can be emitted from the light-emitting holes, thereby forming a small-angle vertical concentrated light emission, which meets the requirements of the light-emitting diode for a small-angle vertical concentrated light emission.

[0007] The present invention also provides a light-emitting device, which includes a plurality of light-emitting diodes arranged in an array, with a spacing between the plurality of light-emitting diodes ranging from 0.1 to 10 μm, and each light-emitting diode adopts the light-emitting diode provided by any of the above embodiments.

[0008] An embodiment of the present invention provides a light emitting diode and a light emitting device, which can allow light to be emitted from a light emitting hole through the setting of a reflective structure with interval coverage, thereby forming small-angle vertical concentrated light emission, thereby meeting the light emitting diode's demand for small-angle vertical concentrated light emission.

[0009] Other features and beneficial effects of the present invention will be described in the following description, and some of the technical features and beneficial effects can be obviously derived from the description or understood by implementing the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, some of the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0011] Figure 1 is a schematic diagram of the bottom structure of a light emitting diode provided by an embodiment of the present invention;

[0012] Figure 2 is along Figure 1 A schematic diagram of a cross-sectional structure taken along the interception line FF;

[0013] Figures 3 to 11 yes Figure 2 The schematic diagram of the structure of the light-emitting diode at each stage in the manufacturing process is shown.

[0014] Reference numerals:

[0015] 10-first semiconductor layer; 101-upper surface; 102-lower surface; 12-light-emitting layer; 14-second semiconductor layer; 16-raised structure; 18-reflective structure; 181-light-emitting hole; 20-transparent conductive layer; 21-first electrode; 22-second electrode; 24-insulating layer; 26-growth substrate; 30-sacrificial layer; 32-bonding layer; 34-transfer substrate; L1-maximum vertical distance from the reflective structure to the first semiconductor layer; L2-maximum vertical distance from the raised structure to the first semiconductor layer; L3-spacing between two adjacent light-emitting holes. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments; the technical features designed in different implementation modes of the present invention described below can be combined with each other as long as they do not conflict with each other; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0017] In the description of the present invention, it should be understood that the terms "center", "lateral", "up", "down", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more. In addition, the term "including" and any variation thereof all mean "at least including".

[0018] See also Figure 1 and Figure 2 , Figure 1 is a bottom structural diagram of a light emitting diode provided by an embodiment of the present invention, Figure 2 is along Figure 1FF is a cross-sectional structural diagram of the embodiment of the present invention. In order to achieve at least one of the above advantages or other advantages, an embodiment of the present invention provides a light emitting diode. As shown in the figure, the light emitting diode may include a first semiconductor layer 10, a light emitting layer 12, a second semiconductor layer 14, a plurality of protruding structures 16 and a reflective structure 18.

[0019] The first semiconductor layer 10 has an upper surface 101 and a lower surface 102 relative to each other. The first semiconductor layer 10 can be an N-type semiconductor layer, which can provide electrons to the light-emitting layer 12 under the action of a power source. In some embodiments, the first semiconductor layer 10 includes an N-type doped nitride layer. The N-type doped nitride layer may include N-type impurities. The N-type impurities may include one of Si, Ge, Sn or a combination thereof. The first semiconductor layer 10 may be a single-layer structure or a multi-layer structure, and the multi-layer structure has different compositions. In some embodiments, the material of the first semiconductor layer 10 may include a GaN-based semiconductor material.

[0020] The light emitting layer 12 is located on the upper surface 101 of the first semiconductor layer 10. The light emitting layer 12 may be a quantum well structure (Quantum Well, referred to as QW). In some embodiments, the light emitting layer 12 may also be a multiple quantum well structure (Multiple Quantum Well, referred to as MQW), wherein the multiple quantum well structure includes multiple quantum well layers (Well) and multiple quantum barrier layers (Barrier) alternately arranged in a repeated manner, for example, it may be a multiple quantum well structure of GaN / AlGaN, InAlGaN / InAlGaN or InGaN / AlGaN. In addition, the composition and thickness of the well layer in the light emitting layer 12 determine the wavelength of the generated light. In order to improve the luminous efficiency of the light emitting layer 12, it can be achieved by changing the depth of the quantum well, the number of layers, thickness and / or other characteristics of the paired quantum wells and quantum barriers in the light emitting layer 12.

[0021] The second semiconductor layer 14 is located above the light emitting layer 12. The second semiconductor layer 14 may be a P-type semiconductor layer, which may provide holes to the light emitting layer 12 under the action of a power source. In some embodiments, the second semiconductor layer 14 includes a P-type doped nitride layer. The P-type doped nitride layer may include one or more P-type impurities. The P-type impurities may include one or a combination of Mg, Zn, and Be. The second semiconductor layer 14 may be a single-layer structure or a multi-layer structure, and the multi-layer structure has different compositions. In addition, the setting of the epitaxial structure is not limited thereto, and other types of epitaxial structures may be selected according to actual needs.

[0022] A plurality of protrusion structures 16 are distributed on the lower surface 102 of the first semiconductor layer 10. The plurality of protrusion structures 16 can be formed by roughening the lower surface 102 of the first semiconductor layer 10. The protrusion structures 16 can increase light extraction, but cannot achieve concentrated light extraction.

[0023] The reflective structure 18 covers a plurality of protruding structures 16 at intervals, and the reflective structure 18 is used to reflect light. Covering at intervals means that the reflective structure 18 does not cover all the protruding structures 16, and the reflective structure 18 has a plurality of light exit holes 181, and the light exit holes 181 expose the protruding structures 16. There is at least one protruding structure 16 between two adjacent light exit holes 181, and the number of light exit holes 181 is less than the number of protruding structures 16. Optionally, the reflective structure 18 covers a plurality of protruding structures 16 at a distance of at least one protruding structure 16. The present invention gathers light at the light exit holes 181 through the provision of the reflective structure 18 that covers at intervals, and emits light vertically through the light exit holes 181, thereby forming small-angle vertical concentrated light output, thereby meeting the requirements of light-emitting diodes for small-angle vertical concentrated light output. Taking a protruding structure 16 located at a light exit hole 181 as an example, the protruding structure 16 is surrounded by a reflective structure 18, and the reflective structure 18 can reflect the light emitted by the light emitting layer 12, so that the light is reflected inside, and the angle of the light emitted from the light exit hole 181 is relatively small (i.e., the light exit angle is small), so the light emitted from the light exit hole 181 of the protruding structure 16 will be emitted as vertically as possible. The vertical direction refers to the direction perpendicular to the upper surface 101 of the first semiconductor layer 10.

[0024] In some embodiments, the reflective structure 18 is a DBR structure, which has a better reflective effect. The DBR structure is composed of a high refractive index sublayer and a low refractive index sublayer alternately stacked. The material of the high refractive index sublayer can be silicon nitride, silicon oxynitride, aluminum oxide or titanium oxide, and the material of the low refractive index sublayer can be silicon oxide. Optionally, the refractive index range of the low refractive index sublayer is 1.3 to 1.7, and the refractive index range of the high refractive index sublayer is 1.7 to 2.7.

[0025] In some embodiments, a plurality of protrusion structures 16 are distributed in an array on the lower surface 102 of the first semiconductor layer 10, and the roughening light extraction effect is better. Optionally, the shape of a single protrusion structure 16 is a cone or a frustum, for example, the longitudinal cross section of a single protrusion structure 16 can be a trapezoid, a triangle or a square.

[0026] Considering the need to allow light to be emitted vertically from the light exit hole 181 as much as possible, the maximum vertical distance L1 from the reflective structure 18 to the upper surface 101 of the first semiconductor layer 10 is set to be greater than the maximum vertical distance L2 from the protruding structure 16 to the upper surface 101 of the first semiconductor layer 10. In other words, the height of the protruding structure 16 after the reflective structure 18 covers it (with the upper surface 101 of the first semiconductor layer 10 as the height reference line) is higher than the height of the protruding structure 16 itself that is not covered by the reflective structure 18, thereby allowing light to be emitted vertically more from the light exit hole 181.

[0027] In some embodiments, the spacing L3 between two adjacent light emitting holes 181 is the same, and the light emission is more uniform. Optionally, the spacing L3 between two adjacent light emitting holes 181 ranges from 0.2 to 4 μm to ensure the light emission performance of the light emitting diode.

[0028] The light emitting diode further includes a transparent conductive layer 20 , an insulating layer 24 , a first electrode 21 and a second electrode 22 .

[0029] The transparent conductive layer 20 is located on the second semiconductor layer 14. The transparent conductive layer 20 is made of a transparent conductive material, which may include indium tin oxide (ITO), indium zinc oxide (IZO), indium oxide (InO), tin oxide (SnO), cadmium tin oxide (CTO), antimony tin oxide (ATO), aluminum zinc oxide (AZO), zinc tin oxide (ZTO), gallium doped zinc oxide (GZO), tungsten doped indium oxide (IWO) or zinc oxide (ZnO), but the embodiments of the present disclosure are not limited thereto.

[0030] The insulating layer 24 covers the first semiconductor layer 10, the light emitting layer 12, the second semiconductor layer 14 and the transparent conductive layer 20. The insulating layer 24 has a first opening and a second opening, the first opening exposes the first semiconductor layer 10, and the second opening exposes the transparent conductive layer 20. The insulating layer 24 has different functions according to the positions involved. For example, when the insulating layer 24 covers the sidewalls of the first semiconductor layer 10 and the second semiconductor layer 14, it can be used to prevent the first semiconductor layer 10 and the second semiconductor layer 14 from being electrically connected due to leakage of conductive materials, thereby reducing the short circuit anomaly of the light emitting diode, but the embodiments of the present disclosure are not limited thereto. The material of the insulating layer 24 includes a non-conductive material. The non-conductive material is preferably an inorganic material or a dielectric material. The inorganic material may include silica gel. The dielectric material includes an electrically insulating material such as aluminum oxide, silicon nitride, silicon oxide, titanium oxide, or magnesium fluoride. For example, the insulating layer 24 may be silicon dioxide, silicon nitride, titanium oxide, tantalum oxide, niobium oxide, barium titanate, or a combination thereof, and the combination thereof may be, for example, a Bragg reflector (DBR) formed by repeatedly stacking two materials with different refractive indices.

[0031] The first electrode 21 is connected to the first semiconductor layer 10 through the first opening. The first electrode 21 can be a single-layer, double-layer or multi-layer structure, for example, a stacked structure of Ti / Al, Ti / Al / Ti / Au, Ti / Al / Ni / Au, V / Al / Pt / Au, etc.

[0032] The second electrode 22 is connected to the transparent conductive layer 20 through the second opening. The second electrode 22 can be a single-layer, double-layer or multi-layer structure, for example, a stacked structure of Ti / Al, Ti / Al / Ti / Au, Ti / Al / Ni / Au, V / Al / Pt / Au, etc.

[0033] See also Figures 3 to 11 , Figures 3 to 11 yes Figure 2 The structure diagram of the light emitting diode at each stage of the manufacturing process is shown below. Figure 2 The light emitting diode method is shown.

[0034] First, if Figure 3 As shown, a first semiconductor layer 10, a light emitting layer 12 and a second semiconductor layer 14 are sequentially deposited on a growth substrate 26. The first semiconductor layer 10, the light emitting layer 12 and the second semiconductor layer 14 are partially etched to expose the mesa of the first semiconductor layer 10.

[0035] Secondly, if Figure 4 As shown, a transparent conductive layer 20 is formed on the second semiconductor layer 14 .

[0036] Then, if Figure 5As shown, an insulating layer 24 is deposited on the first semiconductor layer 10 and the second semiconductor layer 14, and the insulating layer 24 covers the first semiconductor layer 10, the light emitting layer 12, the second semiconductor layer 14 and the transparent conductive layer 20. The insulating layer 24 has a first opening and a second opening. The first opening exposes the first semiconductor layer 10, and the second opening exposes the transparent conductive layer 20.

[0037] Continue, such as Figure 6 As shown, a first electrode 21 and a second electrode 22 are formed on the insulating layer 24. The first electrode 21 is connected to the first semiconductor layer 10 through the first opening. The second electrode 22 is connected to the transparent conductive layer 20 through the second opening.

[0038] Then, if Figure 7 As shown, a sacrificial layer 30 , a bonding layer 32 and a transfer substrate 34 are sequentially disposed above the insulating layer 24 , the first electrode 21 and the second electrode 22 .

[0039] Then, if Figure 8 As shown, the growth substrate 26 located on the lower surface 102 of the first semiconductor layer 10 is removed, and the lower surface 102 of the first semiconductor layer 10 is roughened to form a plurality of protrusion structures 16 .

[0040] Then, if Fig. 9 As shown, a reflective structure 18 is plated on the surface of the protruding structure 16 to cover the entire surface.

[0041] Then, if Fig.10 As shown, photolithography or nanoimprinting is used to set glue in the area where the reflective structure 18 needs to be retained, and no glue is set in the area where the reflective structure 18 does not need to be retained (i.e., the light exit hole 181). Subsequently, ICP etching is used to remove the reflective structure 18 not covered by the glue, thus forming a reflective structure 18 that covers the protruding structure 16 in an intermittent manner. The glue is then removed.

[0042] Finally, if Fig.11 As shown, sacrificial layer 30, bonding layer 32, and transfer substrate 34 are removed.

[0043] The above is only a public one for making Figure 2 The method of manufacturing a light emitting diode shown in the figure is not limited to the present invention, and is only used to illustrate a method of manufacturing a light emitting diode.

[0044] In some embodiments, the size of the light emitting diode is less than or equal to 50 μm, that is, the light emitting diode is suitable for small sizes, such as Micro LED. For applications such as MicroLED watches, it is particularly necessary to be able to concentrate and emit light vertically to improve product performance. The size of the light emitting diode refers to the length or width of the light emitting diode.

[0045] The present invention also provides a light-emitting device, which includes a plurality of light-emitting diodes arranged in an array, with a spacing between the plurality of light-emitting diodes ranging from 0.1 to 10 μm, and each light-emitting diode adopts the light-emitting diode provided by any of the above embodiments.

[0046] An embodiment of the present invention provides a light-emitting diode and a light-emitting device, which can allow light to be emitted from a light-emitting hole 181 by setting a reflective structure 18 with interval coverage, thereby forming small-angle vertical concentrated light emission, thereby meeting the light-emitting diode's demand for small-angle vertical concentrated light emission.

[0047] In addition, those skilled in the art should understand that, although there are many problems in the prior art, each embodiment or technical solution of the present invention can be improved in only one or several aspects, without having to solve all the technical problems listed in the prior art or background technology at the same time. Those skilled in the art should understand that the content not mentioned in a claim should not be used as a limitation on the claim.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A light emitting diode, characterized in that: The light emitting diode comprises: a first semiconductor layer having an upper surface and a lower surface opposite to each other; A light emitting layer, located on the upper surface of the first semiconductor layer; A second semiconductor layer, located on the light-emitting layer; A plurality of protrusion structures, wherein the plurality of protrusion structures are distributed on the lower surface of the first semiconductor layer; The reflective structure covers the plurality of protruding structures in an interval manner. The reflective structure has a plurality of light-emitting holes, the protruding structures are exposed through the light-emitting holes, and at least one protruding structure exists between two adjacent light-emitting holes.

2. The light emitting diode according to claim 1, characterized in that: The reflective structure is a DBR structure, which is composed of alternately stacking high-refractive-index sublayers and low-refractive-index sublayers.

3. The light emitting diode according to claim 1, characterized in that: The number of the light exit holes is less than the number of the protrusion structures.

4. The light emitting diode according to claim 1, characterized in that: The plurality of protrusion structures are distributed in an array on the lower surface of the first semiconductor layer.

5. The light emitting diode according to claim 1, characterized in that: The shape of a single protruding structure is a cone or a frustum.

6. The light emitting diode according to claim 1, characterized in that: A maximum vertical distance from the reflective structure to an upper surface of the first semiconductor layer is greater than a maximum vertical distance from the protruding structure to an upper surface of the first semiconductor layer.

7. The light emitting diode according to claim 1, characterized in that: The distances between two adjacent light exit holes are the same.

8. The light emitting diode according to claim 1, characterized in that: The distance between two adjacent light-emitting holes ranges from 0.2 to 4 μm.

9. The light emitting diode according to claim 1, characterized in that: The light-emitting diode also includes a transparent conductive layer, an insulating layer, a first electrode and a second electrode. The transparent conductive layer is located on the second semiconductor layer. The insulating layer covers the first semiconductor layer, the light-emitting layer, the second semiconductor layer and the transparent conductive layer. The insulating layer has a first opening and a second opening. The first electrode is connected to the first semiconductor layer through the first opening, and the second electrode is connected to the transparent conductive layer through the second opening.

10. The light emitting diode according to claim 1, characterized in that: The size of the light emitting diode is less than or equal to 50 μm.

11. The light emitting diode according to claim 1, characterized in that: The material of the first semiconductor layer includes GaN-based semiconductor material.

12. A light emitting device, characterized in that: The light emitting device comprises a plurality of light emitting diodes arranged in an array, the spacing between the plurality of light emitting diodes is in the range of 0.1 to 10 μm, and each of the light emitting diodes is a light emitting diode as claimed in any one of claims 1 to 11.

Images