Light emitting diode and light emitting device

Abstract

The present application 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 protruding structures and a reflecting structure. The first semiconductor layer has opposite upper and lower surfaces, 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 protruding structures are distributed on the lower surface of the first semiconductor layer, and the reflecting structure covers the plurality of protruding structures in a spaced manner. The reflecting structure has a plurality of light emitting holes, the protruding structures are exposed by the light emitting holes, and there is at least one protruding structure between two adjacent light emitting holes. By arranging the reflecting structure, light can be emitted from the light emitting holes, thereby forming small-angle vertical concentrated light emission, which meets the demand of the light emitting diode for small-angle vertical concentrated light emission.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor manufacturing, in particular to a light emitting diode and a light emitting device. BACKGROUND

[0002] A light emitting diode (LED) is a semiconductor light emitting element, which is usually made of semiconductors such as GaN, GaAs, GaP, GaAsP, etc., and the core is a PN junction with light emitting characteristics. The LED has the advantages of high light intensity, high efficiency, small size, long service life, etc., and is considered to be one of the most potential light sources at present. The LED has been widely used in lighting, monitoring command, high-definition performance, high-end cinema, office display, conference interaction, virtual reality, etc.

[0003] In recent years, Micro LED chips as ultimate display have gradually become commercialized. In vehicle display and watch display, the commercialization requirement for Micro LED chips is that the chips should achieve small-angle vertical light emission perpendicular to the chip plane. At present, due to the advantages of GaN material, the Micro LED chip usually adopts GaN material as epitaxy, so that the light emission surface is GaN surface light emission. However, the refractive index of GaN material and air is very different, which leads to a large total reflection angle, and most of the light will be limited in the GaN layer (epitaxy) 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 still cannot meet the commercialization requirement of small-angle vertical concentrated light emission. Therefore, how to ensure that the Micro LED chip can achieve the effect of small-angle vertical concentrated light emission has become one of the technical problems to be solved in the field.

[0004] It should be noted that the information disclosed in this BACKGROUND section is only intended to increase the understanding of the general background of the present application, and should not be considered as recognition or in any form as admitting that this information constitutes prior art well known by those skilled in the art SUMMARY

[0005] The present application 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 opposite upper and lower surfaces. The light-emitting layer is on the upper surface of the first semiconductor layer. The second semiconductor layer is on the light-emitting layer. A plurality of protruding structures are distributed on the lower surface of the first semiconductor layer. The reflective structure is spacedly covered on the plurality of protruding structures. The reflective structure has a plurality of light-emitting holes, and the light-emitting holes expose the protruding structures. There is at least one protruding structure between two adjacent light-emitting holes. By the arrangement of the spacedly covered reflective structure, light can be emitted from the light-emitting holes, thereby forming small-angle vertical concentrated light emission, meeting the requirement of the light-emitting diode for small-angle vertical concentrated light emission.

[0007] The application further provides a light-emitting device, which comprises a plurality of light-emitting diodes arranged in an array, and the distance between the light-emitting diodes ranges from 0.1 to 10 μm. Each light-emitting diode is the light-emitting diode provided by any one of the above embodiments.

[0008] The application provides a light-emitting diode and a light-emitting device. By the arrangement of the spacedly covered reflective structure, light can be emitted from the light-emitting holes, thereby forming small-angle vertical concentrated light emission, meeting the requirement of the light-emitting diode for small-angle vertical concentrated light emission.

[0009] Other features and advantages of the application will be described in the following description, and some of the features and advantages can be apparent from the description or can be learned by practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0010] In order to more clearly illustrate the technical solutions of the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, some of the drawings below are some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative effort on the basis of these drawings.

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

[0012] Figure 2 is a cross-sectional structure schematic diagram taken along the cutting line F-F shown in Figure 1

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

[0014] Reference signs:

[0015] ​10 - first semiconductor layer; 101 - upper surface; 102 - lower surface; 12 - light emitting layer; 14 - second semiconductor layer; 16 - protruding structure; 18 - reflecting structure; 181 - light exit 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 reflecting structure to first semiconductor layer; L2 - maximum vertical distance from protruding structure to first semiconductor layer; L3 - distance between two adjacent light exit holes. DETAILED DESCRIPTION

[0016] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application; as long as there is no conflict, the technical features in the different embodiments of the present application can be combined with each other; and all other embodiments obtained by a person of ordinary skill in the art based on the embodiments in the present application without creative effort fall into the protection scope of the present application.

[0017] In the description of the present application, it should be understood that the terms "center", "transverse", "upper", "lower", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or component referred to must have a particular orientation, or be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined as "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more. In addition, the term "comprising" and any variation thereof means "at least including".

[0018] Please refer to Figure 1 and Figure 2 , Figure 1 is a schematic diagram of the bottom surface structure of a light emitting diode provided by an embodiment of the present application, Figure 2 is a schematic diagram of the bottom surface structure of a light emitting diode provided by an embodiment of the present application, Figure 1FIG. 4 is a cross-sectional view of the light emitting diode taken along the line F-F of FIG. 3. To achieve at least one or more of the above aspects and / or advantages, an embodiment of the present application provides a light emitting diode. As shown in the drawing, the light emitting diode can include a first semiconductor layer 10, a light emitting layer 12, a second semiconductor layer 14, a plurality of protrusion structures 16, and a reflective structure 18.

[0019] The first semiconductor layer 10 has opposite upper and lower surfaces 101 and 102. The first semiconductor layer 10 can be an N-type semiconductor layer that provides 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 can include an N-type impurity. The N-type impurity can include one or a combination of Si, Ge, and Sn. The first semiconductor layer 10 can be a single layer structure or a multi-layer structure having different compositions. In some embodiments, the material of the first semiconductor layer 10 can 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 can be a quantum well structure (QW). In some embodiments, the light emitting layer 12 can also be a multiple quantum well structure (MQW) including a plurality of quantum well layers (Well) and a plurality of quantum barrier layers (Barrier) alternately arranged in a repeated manner, such as a multiple quantum well structure of GaN / AlGaN, InAlGaN / InAlGaN, or InGaN / AlGaN. In addition, the composition and thickness of the well layers in the light emitting layer 12 determine the wavelength of the generated light. To improve the light emitting efficiency of the light emitting layer 12, the depth of the quantum well, the number of pairs of quantum well and quantum barrier, the thickness, and / or other characteristics in the light emitting layer 12 can be changed.

[0021] The second semiconductor layer 14 is located on the light emitting layer 12. The second semiconductor layer 14 can be a P-type semiconductor layer that provides 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 can include one or more P-type impurities. The P-type impurity can include one or a combination of Mg, Zn, and Be. The second semiconductor layer 14 can be a single layer structure or a multi-layer structure having different compositions. In addition, the epitaxial structure is not limited to this and other types of epitaxial structures can be selected according to actual needs.

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

[0023] The reflective structure 18 covers the plurality of protruding structures 16 in a spaced manner, and the reflective structure 18 is used for reflecting light. The spaced manner means that the reflective structure 18 does not cover all the protruding structures 16, and the reflective structure 18 has a plurality of light extraction holes 181 exposing the protruding structures 16. There are at least one protruding structure 16 between two adjacent light extraction holes 181, and the number of the light extraction holes 181 is less than the number of the protruding structures 16. Alternatively, the reflective structure 18 covers the plurality of protruding structures 16 at a distance of at least one protruding structure 16. The present application can concentrate light at the light extraction holes 181 by the arrangement of the reflective structure 18 covering in a spaced manner, and the light is extracted vertically through the light extraction holes 181, thereby forming small-angle vertical concentrated light extraction, which meets the demand of the light-emitting diode for small-angle vertical concentrated light extraction. Taking one protruding structure 16 located at the light extraction hole 181 as an example, the periphery of the protruding structure 16 is covered by the 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 extraction hole 181 is small (i.e. the light extraction angle is small), and thus the light emitted from the light extraction hole 181 of the protruding structure 16 is extracted vertically as much 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 better light reflection effect. The DBR structure is formed by alternately stacking high-refractive-index sublayers and low-refractive-index sublayers. 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. Alternatively, the refractive index of the low-refractive-index sublayer ranges from 1.3 to 1.7, and the refractive index of the high-refractive-index sublayer ranges from 1.7 to 2.7.

[0025] In some embodiments, the plurality of protruding structures 16 are distributed in an array on the lower surface 102 of the first semiconductor layer 10, which has better roughened light extraction effect. Alternatively, the shape of a single protruding structure 16 is conical or frustoconical, for example, the longitudinal section of a single protruding structure 16 can be trapezoidal, triangular or square, etc.

[0026] In order to make the light emitted from the light emitting diode exit the light emitting hole 181 as vertically as possible, the maximum vertical distance L1 of the reflection structure 18 to the upper surface 101 of the first semiconductor layer 10 is greater than the maximum vertical distance L2 of the protruding structure 16 to the upper surface 101 of the first semiconductor layer 10. That is, the height of the reflection structure 18 after covering the protruding structure 16 (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 not covered by the reflection structure 18, so that the light emitted from the light emitting diode exits the light emitting hole 181 more vertically.

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

[0028] The light emitting diode further comprises 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 can 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 position involved, for example, when the insulating layer 24 covers the sidewall 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 the leakage of conductive material, reducing the short-circuit abnormality 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 can include silica gel. The dielectric material includes electrically insulating materials such as aluminum oxide, silicon nitride, silicon oxide, titanium oxide, or magnesium fluoride. For example, the insulating layer 24 can be silicon dioxide, silicon nitride, titanium oxide, tantalum oxide, niobium oxide, barium titanate, or a combination thereof, which can be a Bragg reflector (DBR) formed by repeatedly stacking two materials with different refractive indices, for example.

[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: Ti / Al, Ti / Al / Ti / Au, Ti / Al / Ni / Au, V / Al / Pt / Au and the like.

[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: Ti / Al, Ti / Al / Ti / Au, Ti / Al / Ni / Au, V / Al / Pt / Au and the like.

[0033] Referring to Figures 3 to 11 , Figures 3 to 11 is Figure 2 the structure of the light emitting diode at each stage of the manufacturing process. A method for manufacturing the light emitting diode shown in Figure 2 is disclosed below.

[0034] First, as shown in Figure 3 , the first semiconductor layer 10, the light emitting layer 12 and the second semiconductor layer 14 are sequentially deposited on the 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] Second, as shown in Figure 4 , the transparent conductive layer 20 is formed on the second semiconductor layer 14.

[0036] Then, as shown in Figure 5As shown, an insulating layer 24 is deposited on the first semiconductor layer 10 and the second semiconductor layer 14, covering 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] Next, as shown, Figure 6 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, as shown, Figure 7 a sacrificial layer 30, a bonding layer 32 and a transfer substrate 34 are sequentially arranged above the insulating layer 24, the first electrode 21 and the second electrode 22.

[0039] Then, as shown, Figure 8 the growth substrate 26 located at the lower surface 102 of the first semiconductor layer 10 is removed, and the lower surface 102 of the first semiconductor layer 10 is subjected to a surface roughening treatment to form a plurality of protruding structures 16.

[0040] Then, as shown, Figure 9 a full-area reflective structure 18 is plated on the surface of the protruding structure 16.

[0041] Then, as shown, Figure 10 a photoresist or nanoimprint is used to set a resist in the area where the reflective structure 18 needs to be reserved, and no resist is set in the area where the reflective structure 18 does not need to be reserved (i.e. at the light-emitting hole 181). Subsequently, ICP etching is performed, and the reflective structure 18 not covered by the resist is removed, thereby forming the reflective structure 18 spacedly covering the protruding structure 16. The resist is then removed.

[0042] Finally, as shown, Figure 11 the sacrificial layer 30, the bonding layer 32 and the transfer substrate 34 are removed.

[0043] The above only discloses one method for manufacturing the light-emitting diode shown, Figure 2 and the present case is not limited thereto, but is only used to illustrate one implementation manner of the light-emitting diode.

[0044] In some embodiments, the size of the light-emitting diode is less than or equal to 50 μm, i.e. the light-emitting diode is suitable for small sizes such as Micro LED. For applications in the field of Micro LED watches, it is particularly necessary for the light to be concentrated and vertically emitted, thereby improving the performance of the product. The size of the light-emitting diode refers to the length or width of the light-emitting diode.

[0045] The application further provides a light emitting device, which comprises a plurality of light emitting diodes arranged in an array, the interval between the light emitting diodes ranges from 0.1 to 10 microns, and each light emitting diode is the light emitting diode provided by any one of the above embodiments.

[0046] The light emitting diode and the light emitting device provided by the embodiment of the application can make light emit from the light emitting hole 181 through the arrangement of the interval covered reflection structure 18, and further form small-angle vertical concentrated light emission, thereby meeting the demand of the light emitting diode 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 application can only be improved in one or several aspects, and it is not necessary to solve all the technical problems listed in the prior art or the background art at the same time. Those skilled in the art should understand that the content not mentioned in a claim should not be regarded as a limitation of the claim.

[0048] Finally, it should be pointed out that: the above embodiments are only used to illustrate the technical solutions of the application, and not to limit them; although the application has been described in detail with reference to the above embodiments, those skilled in the art should understand that: they can still modify the technical solutions recorded in the above embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solutions of the embodiments of the application.

Claims

1. A light-emitting diode, characterized in that: The light-emitting diode includes: The first semiconductor layer has opposing upper and lower surfaces; A light-emitting layer is located on the upper surface of the first semiconductor layer; A second semiconductor layer is located above the light-emitting layer; Multiple protrusion structures are distributed on the lower surface of the first semiconductor layer; A reflective structure is provided, which covers the plurality of protruding structures at intervals. The reflective structure has a plurality of light-emitting holes, which expose the protruding structures. The protruding structures are covered by the reflective structure on all sides, and there is at least one protruding structure 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 alternating stacks of high-refractive-index sublayers and low-refractive-index sublayers.

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

4. The light-emitting diode according to claim 1, characterized in that: The plurality of protrusion structures are arranged 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 protrusion is conical or frustum.

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

7. The light-emitting diode according to claim 1, characterized in that: The spacing between two adjacent light-emitting holes is the same.

8. The light-emitting diode according to claim 1, characterized in that: The spacing 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 further 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 materials.

12. A light-emitting device, characterized in that: The light-emitting device includes a plurality of light-emitting diodes, which are arranged in an array and the spacing between the plurality of light-emitting diodes ranges from 0.1 to 10 μm. Each of the light-emitting diodes is a light-emitting diode as described in any one of claims 1 to 11.

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