Light emitting diode capable of improving light reflection effect and preparation method thereof

Abstract

The invention provides a light-emitting diode capable of improving a light reflection effect and a preparation method thereof, and belongs to the technical field of photoelectron manufacturing. The light-emitting diode comprises an epitaxial layer, a transparent conducting layer, a passivation layer, a first reflecting layer, a second reflecting layer and a protective layer, the transparent conducting layer is located on the surface of the epitaxial layer, and the transparent conducting layer is wrapped by the passivation layer; the first reflection layer is located on the surface of the passivation layer, the first reflection layer is connected with the transparent conductive layer through a through hole in the passivation layer, and the protection layer wraps the first reflection layer; the second reflection layer is located in the passivation layer and located between the surface, away from the epitaxial layer, of the passivation layer and the surface, close to the epitaxial layer, of the passivation layer, and at least part of the orthographic projection of the second reflection layer on the surface, away from the passivation layer, of the epitaxial layer is overlapped with the orthographic projection of the protection layer on the surface, away from the passivation layer, of the epitaxial layer. The light reflecting effect of the light emitting diode on the backlight side can be improved, and therefore the light emitting brightness of the light emitting side of the light emitting diode is improved.

Description

Technical Field

[0001] The present disclosure relates to the field of optoelectronic manufacturing technology, and in particular to a light emitting diode with improved reflective effect and a preparation method thereof. Background Art

[0002] Light Emitting Diode (LED) is a common product. LED is usually manufactured by manufacturing various film layers on a substrate, performing graphic processing, and then cutting to form individual LED core particles.

[0003] In the related art, a light-emitting diode generally includes an epitaxial layer, a transparent conductive layer, a passivation layer, a silver mirror reflective layer and a protective layer. The epitaxial layer, the transparent conductive layer and the passivation layer are stacked in sequence, and the silver mirror reflective layer is located on the surface of the passivation layer away from the epitaxial layer. Since the metal Ag in the silver mirror reflective layer is easy to migrate, a protective layer is formed on the surface of the passivation layer to cover the silver mirror reflective layer to prevent the metal Ag from migrating.

[0004] If you want to completely block the Ag migration of the silver mirror reflection layer, you often need to wrap the side wall of the silver mirror reflection layer with a protective layer. Therefore, it is difficult for the silver mirror reflection layer to completely cover the epitaxial layer. The protective layer is mostly made of metals such as Cr and Ti that have low reflectivity and can effectively block metal migration. Therefore, when the light emitted from the epitaxial layer is emitted to the protective layer, the reflectivity in the area where the protective layer is located is low, thereby affecting the light output brightness of the light-emitting diode. Summary of the invention

[0005] The embodiment of the present disclosure provides a light emitting diode with improved reflective effect and a method for manufacturing the same, which can improve the reflective effect of the light emitting diode on the backlight side, thereby increasing the light output brightness on the light output side of the light emitting diode. The technical solution is as follows:

[0006] On the one hand, an embodiment of the present disclosure provides a light-emitting diode, which includes: an epitaxial layer, a passivation layer, a first reflective layer, a second reflective layer and a protective layer, wherein the passivation layer is located on the surface of the epitaxial layer; the first reflective layer is located on the surface of the passivation layer away from the epitaxial layer, the first reflective layer is electrically connected to the epitaxial layer through a through hole on the passivation layer, the protective layer is located on the surface of the passivation layer away from the epitaxial layer, and wraps the first reflective layer; the second reflective layer is located in the passivation layer, and is located between the surface of the passivation layer away from the epitaxial layer and the surface close to the epitaxial layer, and at least part of the orthographic projection of the second reflective layer on the surface of the epitaxial layer away from the passivation layer overlaps with the orthographic projection of the protective layer on the surface of the epitaxial layer away from the passivation layer.

[0007] Optionally, at least part of an orthographic projection of a peripheral edge of the first reflective layer on a surface of the epitaxial layer away from the passivation layer overlaps with an orthographic projection of the second reflective layer on a surface of the epitaxial layer away from the passivation layer.

[0008] Optionally, the protection layer surrounds a portion of the side wall of the first reflective layer, and an orthographic projection of the second reflective layer on a surface of the epitaxial layer away from the passivation layer is located within an orthographic projection of the second reflective layer on a surface of the epitaxial layer away from the passivation layer.

[0009] Optionally, the epitaxial layer includes a first semiconductor layer, a multi-quantum well layer, and a second semiconductor layer stacked in sequence, the second semiconductor layer having a groove exposing the first semiconductor layer; the second reflective layer is located on the second semiconductor layer and outside the groove; or, the second reflective layer is located on the second semiconductor layer, the sidewall of the groove and the first semiconductor layer.

[0010] Optionally, the light emitting diode further includes an electrode, the electrode is at least in the groove, and the reflectivity of the electrode is greater than the reflectivity of the protective layer.

[0011] Optionally, the electrode includes at least one of a Cr layer, an Al layer, a Pt layer and a Ti layer.

[0012] Optionally, the reflectivity of the second reflective layer is greater than that of the protective layer, and the reflectivity of the second reflective layer is greater than 60%.

[0013] Optionally, the second reflective layer includes an Ag layer; or, the second reflective layer includes an adhesion metal layer and an Ag layer, and the adhesion metal layer is located on at least one surface of the Ag layer.

[0014] Optionally, a ratio of a thickness of the second reflective layer to a thickness of the passivation layer is less than or equal to 0.8.

[0015] The embodiment of the present disclosure provides a method for preparing a light-emitting diode, the method comprising: preparing an epitaxial layer; forming a transparent conductive layer on the surface of the epitaxial layer; forming a passivation layer and a second reflective layer on the surface of the epitaxial layer, the second reflective layer being located in the passivation layer and between the surface of the passivation layer away from the epitaxial layer and the surface close to the epitaxial layer, and the passivation layer wraps the transparent conductive layer; forming a first reflective layer and a protective layer on the surface of the passivation layer away from the epitaxial layer, the first reflective layer being connected to the transparent conductive layer through a through hole on the passivation layer, the protective layer being located on the surface of the passivation layer away from the epitaxial layer and wraps the first reflective layer, at least part of the orthographic projection of the second reflective layer on the surface of the epitaxial layer away from the passivation layer overlaps with the orthographic projection of the protective layer on the surface of the epitaxial layer away from the passivation layer.

[0016] The beneficial effects brought by the technical solution provided by the embodiments of the present disclosure include at least:

[0017] The light-emitting diode provided by the embodiment of the present disclosure is also embedded with a second reflective layer in the passivation layer below the protective layer, and the second reflective layer is located between the surface of the passivation layer away from the epitaxial layer and the surface close to the epitaxial layer, so as to avoid the second reflective layer from contacting with other film layers, which may cause the light-emitting diode to have a short circuit problem. Among them, at least part of the orthographic projection of the second reflective layer on the surface of the epitaxial layer away from the passivation layer is located within the orthographic projection of the protective layer on the surface of the epitaxial layer away from the passivation layer. That is, at least part of the orthographic projection of the second reflective layer overlaps with the orthographic projection of the protective layer. In this way, when the light emitted from the epitaxial layer irradiates the overlapping area of ​​the protective layer and the second reflective layer, the light will be reflected at the second reflective layer located below the protective layer. That is, the second reflective layer is used to replace the protective layer to reflect the light, so as to improve the reflective effect of the light-emitting diode in the area other than the first reflective layer on the backlight side, so that more light can be emitted from the light-emitting surface of the light-emitting diode, thereby improving the light-emitting brightness of the light-emitting side of the light-emitting diode. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 It is a structural schematic diagram of a light emitting diode provided by the related technology;

[0020] Figure 2 is a structural schematic diagram of a light emitting diode provided by an embodiment of the present disclosure;

[0021] Figure 3 is a schematic structural diagram of another light emitting diode provided by an embodiment of the present disclosure;

[0022] Figure 4 is another schematic diagram of the structure of a light emitting diode provided by an embodiment of the present disclosure;

[0023] Figure 5 is a flow chart of manufacturing a light emitting diode provided by an embodiment of the present disclosure;

[0024] Figure 6 It is a preparation state diagram of a light emitting diode provided by the present disclosure;

[0025] Figure 7 It is a preparation state diagram of a light emitting diode provided by the present disclosure;

[0026] Figure 8 It is a preparation state diagram of a light emitting diode provided by the present disclosure;

[0027] Fig. 9 It is a preparation state diagram of a light emitting diode provided by the present disclosure;

[0028] Fig.10 It is a preparation state diagram of a light emitting diode provided by the present disclosure;

[0029] Fig.11 This is a comparison diagram of the brightness ratio of a light-emitting diode provided by an embodiment of the present disclosure.

[0030] The descriptions of the marks in the figure are as follows:

[0031] 10. Substrate;

[0032] 20. epitaxial layer; 21. first semiconductor layer; 22. multi-quantum well layer; 23. second semiconductor layer; 24. groove;

[0033] 30. Transparent conductive layer;

[0034] 40. passivation layer; 41. first insulating layer; 42. second insulating layer;

[0035] 50, silver mirror reflection layer; 51, first reflection layer; 52, second reflection layer; 53, protective layer;

[0036] 60. Electrode;

[0037] 70. Soldering pad. DETAILED DESCRIPTION

[0038] In order to make the objectives, technical solutions and advantages of the present disclosure more clear, the embodiments of the present disclosure will be further described in detail below with reference to the accompanying drawings.

[0039] Unless otherwise defined, the technical terms or scientific terms used herein shall have the usual meanings understood by persons with ordinary skills in the field to which the present disclosure belongs. The words "first", "second", "third" and similar words used in the patent application specification and claims of the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one" or "one" do not indicate a quantity limitation, but indicate the existence of at least one. Words such as "include" or "comprise" and similar words mean that the elements or objects appearing before "include" or "comprise" include the elements or objects listed after "include" or "comprise" and their equivalents, and do not exclude other elements or objects. Words such as "connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right", "top", "bottom" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0040] Figure 1 It is a schematic diagram of the structure of a light emitting diode provided by the related technology. Figure 1 As shown, in the related art, the light emitting diode includes an epitaxial layer 20, a transparent conductive layer 30, a passivation layer 40, a silver mirror reflection layer 50 and a protective layer 53. The epitaxial layer 20, the transparent conductive layer 30 and the passivation layer 40 are stacked in sequence, and the silver mirror reflection layer 50 is located on the surface of the passivation layer 40 away from the epitaxial layer 20. Since the metal Ag of the silver mirror reflection layer 50 is easy to migrate, the protective layer 53 is formed on the surface of the passivation layer 40 to cover the silver mirror reflection layer to prevent the metal Ag from migrating.

[0041] like Figure 1 As shown by the middle arrow, part of the light emitted by the epitaxial layer 20 passes through the transparent conductive layer 30 and the passivation layer 40 to the silver mirror reflection layer 50 and is reflected back to the light emitting surface of the light emitting diode at the silver mirror reflection layer 50 . The other part passes through the transparent conductive layer 30 and the passivation layer 40 to the protective layer 53 .

[0042] However, the protective layer 53 is mostly made of metals such as Cr and Ti, which have low reflectivity and can effectively block metal migration. Therefore, when the light emitted from the epitaxial layer 20 reaches the protective layer 53, the reflectivity in the area where the protective layer 53 is located is low, thereby affecting the light brightness of the light-emitting diode.

[0043] To this end, an embodiment of the present disclosure provides a light emitting diode. Figure 2 Schematic diagram of the structure of a light emitting diode provided by an embodiment of the present disclosure. Figure 2As shown, the light emitting diode comprises: an epitaxial layer 20 , a passivation layer 40 , a first reflective layer 51 , a second reflective layer 52 and a protective layer 53 . The passivation layer 40 is located on the surface of the epitaxial layer 20 .

[0044] like Figure 2 As shown, the first reflective layer 51 is located on the surface of the passivation layer 40 away from the epitaxial layer 20, and the first reflective layer 51 is electrically connected to the epitaxial layer 20 through the through hole on the passivation layer 40. The protective layer 53 is located on the surface of the passivation layer 40 away from the epitaxial layer 20 and wraps the first reflective layer 51.

[0045] like Figure 2 As shown, the second reflective layer 52 is located in the passivation layer 40, and the second reflective layer 52 is located between the surface of the passivation layer 40 away from the epitaxial layer 20 and the surface close to the epitaxial layer 20, and at least a portion of the orthographic projection of the second reflective layer 52 on the surface of the epitaxial layer 20 away from the passivation layer 40 overlaps with the orthographic projection of the protective layer 53 on the surface of the epitaxial layer 20 away from the passivation layer 40.

[0046] The light-emitting diode provided in the embodiment of the present disclosure further has a second reflective layer 52 embedded in the passivation layer 40 below the protective layer 53, and the second reflective layer 52 is located between the surface of the passivation layer 40 away from the epitaxial layer 20 and the surface close to the epitaxial layer 20, so as to avoid the second reflective layer 52 from contacting other film layers, which may cause the light-emitting diode to have a short circuit. Among them, at least part of the orthographic projection of the second reflective layer 52 on the surface of the epitaxial layer 20 away from the passivation layer 40 is located within the orthographic projection of the protective layer 53 on the surface of the epitaxial layer 20 away from the passivation layer 40. That is, at least part of the orthographic projection of the second reflective layer 52 overlaps with the orthographic projection of the protective layer 53.

[0047] like Figure 2 As shown by the middle arrow, when the light emitted from the epitaxial layer 20 irradiates the overlapping area of ​​the protective layer 53 and the second reflective layer 52, the light will be reflected at the second reflective layer 52 located below the protective layer 53. That is, the second reflective layer 52 is used to reflect the light instead of the protective layer 53, so as to improve the reflective effect of the area other than the first reflective layer 51 on the backlight side of the light-emitting diode, so that more light can be emitted from the light-emitting surface of the light-emitting diode, thereby improving the light-emitting brightness of the light-emitting side of the light-emitting diode.

[0048] Alternatively, if Figure 2 As shown, the light emitting diode also includes a transparent conductive layer 30, which is located on the surface of the epitaxial layer 20, and the passivation layer 40 is located on the surface of the epitaxial layer 20, and the passivation layer 40 wraps the transparent conductive layer 30, and the first reflective layer 51 is connected to the transparent conductive layer 30 through a through hole on the passivation layer 40.

[0049] Optionally, the transparent conductive layer 30 may be an indium tin oxide (ITO) layer, which has good transmittance and low resistivity.

[0050] For example, the transparent conductive layer 30 may be an indium zinc oxide (IZO) layer, which has good transmittance and low resistivity.

[0051] Among them, using an ITO layer or an IZO layer as the transparent conductive layer 30 can allow more light to be transmitted from the transparent conductive layer 30, thereby ensuring the light output effect; at the same time, due to the low resistivity, the electrode 60 is stacked on the transparent conductive layer 30, so that the carriers can be more efficiently conducted from the electrode 60 to the epitaxial layer 20, thereby improving the injection efficiency.

[0052] Exemplarily, the thickness of the transparent conductive layer 30 may be 600 angstroms to 2000 angstroms. For example, the thickness of the transparent conductive layer 30 is 1500 angstroms.

[0053] Optionally, the passivation layer 40 may be at least one of a silicon oxide layer, a titanium oxide layer, and an aluminum oxide layer.

[0054] Exemplarily, the passivation layer 40 may be a silicon oxide layer.

[0055] Alternatively, if Figure 2 As shown, at least part of the orthographic projection of the peripheral edge of the first reflective layer 51 on the surface of the epitaxial layer 20 away from the passivation layer 40 overlaps with the orthographic projection of the second reflective layer 52 on the surface of the epitaxial layer 20 away from the passivation layer 40 .

[0056] In this way, the orthographic projection of the peripheral edge of the first reflective layer 51 overlaps with the orthographic projection of the second reflective layer 52, so that the second reflective layer 52 is disposed around the peripheral edge of the first reflective layer 51. Each interface where the peripheral edge of the first reflective layer 51 contacts the protective layer 53 can be shielded by the second reflective layer 52, thereby preventing light from being emitted to the protective layer 53 and affecting the reflective effect.

[0057] Alternatively, if Figure 2 As shown, the protection layer 53 surrounds a portion of the sidewall of the first reflective layer 51 , and its orthographic projection on the surface of the epitaxial layer 20 away from the passivation layer 40 is located within the orthographic projection of the second reflective layer 52 on the surface of the epitaxial layer 20 away from the passivation layer 40 .

[0058] In the above implementation, the orthographic projection of the portion of the side wall of the first reflective layer 51 covered by the protective layer 53 is completely within the orthographic projection of the second reflective layer 52, that is, the second reflective layer 52 completely blocks the portion of the side wall of the first reflective layer 51 covered by the protective layer 53. In this way, the portion of the protective layer 53 located on the side of the first reflective layer 51 can be blocked by the second reflective layer 52, thereby preventing light from being emitted to the protective layer 53 and affecting the reflective effect.

[0059] Alternatively, if Figure 2 As shown, the epitaxial layer 20 includes a first semiconductor layer 21, a multi-quantum well layer 22, and a second semiconductor layer 23 stacked in sequence, and the second semiconductor layer 23 has a groove 24 exposing the first semiconductor layer 21. The passivation layer 40 is also located in the groove 24, and the passivation layer 40 located in the groove 24 has a via hole exposing the first semiconductor layer 21.

[0060] Optionally, one of the first semiconductor layer 21 and the second semiconductor layer 23 is an n-type layer, and the other of the first semiconductor layer 21 and the second semiconductor layer 23 is a p-type layer.

[0061] Exemplarily, the first semiconductor layer 21 is an n-type layer, and the second semiconductor layer 23 is a p-type layer.

[0062] Optionally, the n-type layer is a silicon-doped n-type GaN layer. The thickness of the n-type GaN layer may be 0.5 μm to 3 μm.

[0063] Optionally, the multi-quantum well layer 22 includes alternately grown InGaN quantum well layers and GaN quantum barrier layers. The multi-quantum well layer 22 may include 3 to 8 periods of alternately stacked InGaN quantum well layers and GaN quantum barrier layers.

[0064] As an example, in the embodiment of the present disclosure, the multi-quantum well layer 22 includes five periods of alternately stacked InGaN quantum well layers and GaN quantum barrier layers.

[0065] Optionally, the thickness of the multi-quantum well layer 22 may be 150 nm to 200 nm.

[0066] Optionally, the p-type layer is a magnesium-doped p-type GaN layer. The thickness of the p-type GaN layer may be 0.5 μm to 3 μm.

[0067] In one implementation of the present disclosure, Figure 2 As shown, the second reflective layer 52 is located on the second semiconductor layer 23 , and the second reflective layer 52 is located outside the groove 24 .

[0068] In the above implementation, the second reflective layer 52 is only disposed above the second semiconductor layer 23 and does not extend into the groove 24. Since the light emitting area of ​​the epitaxial layer 20 is located in the multi-quantum well layer 22, the area with the largest light output on the epitaxial layer 20 is concentrated in the area where the second semiconductor layer 23 on the multi-quantum well layer 22 is located. Therefore, only disposing the second reflective layer 52 above the second semiconductor layer 23 can achieve the purpose of reflecting most of the light, and reduce the preparation area of ​​the second reflective layer 52, thereby reducing the difficulty of preparation.

[0069] In another implementation of the present disclosure, Figure 3 FIG. 1 is a schematic diagram of the structure of another light emitting diode provided by an embodiment of the present disclosure. Figure 3 As shown, the second reflective layer 52 is located on the second semiconductor layer 23 , the sidewall of the groove 24 and the first semiconductor layer 21 .

[0070] In the above implementation, the second reflective layer 52 is not only disposed on the second semiconductor layer 23 , but also extends into the groove 24 to cover the sidewall of the groove 24 and at least a portion of the first semiconductor layer 21 .

[0071] In this way, the second reflective layer 52 can cover the epitaxial layer 20 to the greatest extent, and reflect light more comprehensively, so that the light emitted from the side wall of the groove 24 can also be reflected back to the light emitting surface of the light emitting diode, thereby improving the reflective effect.

[0072] Alternatively, if Figure 2 , 3 As shown, the light emitting diode further includes an electrode 60 and a first insulating layer 41. The first insulating layer 41 is located on the passivation layer 40, extends into the groove 24, and covers the first semiconductor layer 21. The first insulating layer 41 is also provided with a via hole exposing the first semiconductor layer 21.

[0073] like Figure 2 , 3 As shown, the electrode 60 is at least in the groove 24, and the electrode 60 is located on the first insulating layer 41 and connected to the first semiconductor layer through a via hole.

[0074] The reflectivity of the electrode 60 is greater than the reflectivity of the protective layer 53 .

[0075] Exemplarily, the electrode 60 may include at least one of a Cr layer, an Al layer, a Pt layer, and a Ti layer. The reflectivity of these metals is between 60% and 90%.

[0076] Exemplarily, the protective layer 53 may be made of metals such as Ti and TiW, and the reflectivity of these metals is less than 60%.

[0077] By using an electrode 60 with a reflectivity greater than that of the protective layer 53 , the electrode 60 reflects light in the area not covered by the second reflective layer 52 and the first reflective layer 51 , thereby achieving maximum light reflection and improving the light reflection effect of the light emitting diode.

[0078] Optionally, the first insulating layer 41 may be at least one of a silicon oxide layer, a titanium oxide layer, and an aluminum oxide layer.

[0079] Exemplarily, the first insulating layer 41 may be a silicon oxide layer.

[0080] Optionally, the first reflective layer 51 includes an Ag layer, a Ni layer, and a TiW layer stacked in sequence.

[0081] Since Ag has a good reflective effect, providing an Ag layer in the reflective layer can enhance the reflection of light by the reflective layer and improve the light emitting brightness of the light emitting surface of the light emitting diode.

[0082] The Ni layer has good corrosion resistance and wear resistance, and the TiW layer can be successfully deposited on other films as an adhesion layer without peeling or cracking. The alternating stacked Ni and TiW layers can act as a barrier layer to protect the silver mirror.

[0083] Exemplarily, the thickness of the Ag layer is 1400 angstroms to 1700 angstroms. For example, the thickness of the Ag layer is 1500 angstroms.

[0084] Exemplarily, the thickness of the Ni layer is 100 angstroms to 300 angstroms. For example, the thickness of the Ni layer is 200 angstroms.

[0085] Exemplarily, the thickness of the TiW layer is 700 angstroms to 1000 angstroms. For example, the thickness of the TiW layer is 800 angstroms.

[0086] Optionally, the reflectivity of the second reflective layer 52 is greater than the reflectivity of the protective layer 53 , and the reflectivity of the second reflective layer 52 is greater than 60%.

[0087] The second reflective layer 52 with a higher reflectivity is used to shield the protective layer 53, so as to ensure that the reflective effect of the second reflective layer 52 is higher than that of the protective layer 53, thereby improving the reflective effect of the light emitting diode.

[0088] Optionally, the second reflective layer 52 includes an Ag layer. Since Ag has a good reflective effect, providing an Ag layer in the reflective layer can enhance the reflection of light by the reflective layer and improve the light emitting brightness of the light emitting surface of the light emitting diode.

[0089] Exemplarily, the thickness of the Ag layer is 2000 angstroms to 3000 angstroms. For example, the thickness of the Ag layer is 2500 angstroms.

[0090] Optionally, the second reflective layer 52 includes an adhesion metal layer and an Ag layer, and the adhesion metal layer is located on at least one surface of the Ag layer.

[0091] Exemplarily, the second reflective layer 52 includes two adhesion metal layers, and the two adhesion metal layers are respectively located on two opposite surfaces of the Ag layer.

[0092] The adhesion metal layer is disposed in the second reflection layer 52 , and the second reflection layer 52 can be stably connected to the passivation layer 40 by utilizing the good adhesion between the adhesion metal layer and the passivation layer 40 .

[0093] Exemplarily, the adhesion metal layer includes a Ti layer. Metal Ti has good adhesion and can firmly connect the second reflective layer 52 and the passivation layer 40 together.

[0094] Exemplarily, the thickness of the Ag layer is 800 angstroms to 2000 angstroms. For example, the thickness of the Ag layer is 1000 angstroms.

[0095] Exemplarily, the thickness of the adhesion metal layer is 100 angstroms to 500 angstroms. Providing a thinner adhesion metal layer can save costs.

[0096] Optionally, a ratio of the thickness of the second reflective layer 52 to the thickness of the passivation layer 40 is less than or equal to 0.8.

[0097] By setting the ratio of the thickness of the second reflective layer 52 to the thickness of the passivation layer 40 within the above range, it is possible to avoid the second reflective layer 52 being too thick, which would cause the passivation layer 40 on both sides of the second reflective layer 52 to be too thin, thereby preventing the passivation layer 40 from being easily worn away and exposing the second reflective layer 52, thereby causing the problem of short circuit of the light-emitting diode.

[0098] Exemplarily, the ratio of the thickness of the second reflective layer 52 to the thickness of the passivation layer 40 is 0.5.

[0099] Figure 4 FIG. 1 is another schematic diagram of a light emitting diode structure provided by an embodiment of the present disclosure. Figure 4 As shown, the light emitting diode may further include a second insulating layer 42 and a pad 70 . The second insulating layer 42 is located on the surface of the first insulating layer 41 . The second insulating layer 42 has a via hole exposing the electrode 60 . The pad 70 is located on the second insulating layer 42 and connected to the electrode 60 through the via hole.

[0100] Alternatively, the second insulating layer 42 may be at least one of a silicon oxide layer, a titanium oxide layer, and an aluminum oxide layer.

[0101] Exemplarily, the second insulating layer 42 may be a silicon oxide layer.

[0102] Optionally, the pad 70 includes a first Al layer, a first Ti layer, a second Al layer, a second Ti layer, and an Au layer stacked in sequence.

[0103] The thickness of the first Al layer is 8000 angstroms to 12000 angstroms, the thickness of the first Ti layer is 100 angstroms to 500 angstroms, the thickness of the second Al layer is 8000 angstroms to 12000 angstroms, the thickness of the second Ti layer is 500 angstroms to 1500 angstroms, and the thickness of the Au layer is 2000 angstroms to 5000 angstroms.

[0104] For example, the thickness of the first Al layer is 10000 angstroms, the thickness of the first Ti layer is 200 angstroms, the thickness of the second Al layer is 10000 angstroms, the thickness of the second Ti layer is 1000 angstroms, and the thickness of the Au layer is 3000 angstroms.

[0105] Alternatively, if Figure 2 , 3 As shown, the light emitting diode further includes a substrate 10 , and an epitaxial layer 20 is stacked on the substrate 10 .

[0106] For example, the substrate may be a sapphire substrate. The sapphire substrate has a relatively high light transmittance, that is, the substrate is a transparent substrate. In addition, the sapphire material is relatively hard and has relatively stable chemical properties, so that the LED has good luminous effect and stability.

[0107] Figure 5 FIG. 1 is a flow chart of manufacturing a light emitting diode according to an embodiment of the present disclosure. Figure 5 As shown, the preparation method comprises:

[0108] Step S11: preparing the epitaxial layer 20 .

[0109] The process of preparing the epitaxial layer 20 may include the following steps:

[0110] The first step, such as Figure 6 As shown, the epitaxial layer 20 grown on the sapphire substrate includes a first semiconductor layer 21, a multi-quantum well layer 22 and a second semiconductor layer 23 stacked in sequence.

[0111] The sapphire substrate may be pre-treated, placed in a MOCVD (Metal-organic Chemical Vapor Deposition) reaction chamber, and baked for 12 to 18 minutes. As an example, in the embodiment of the present disclosure, the sapphire substrate is baked for 15 minutes.

[0112] Specifically, the baking temperature may be 1000° C. to 1200° C., and the pressure in the MOCVD reaction chamber during baking may be 100 mbar to 200 mbar.

[0113] For example, the first semiconductor layer 21 may be an n-type layer, and the second semiconductor layer 23 may be a p-type layer.

[0114] Optionally, the n-type layer is a silicon-doped n-type GaN layer. The thickness of the n-type GaN layer may be 0.5 μm to 3 μm.

[0115] The growth temperature of the n-type GaN layer may be 1000° C. to 1100° C., and the growth pressure of the n-type GaN layer may be 100 torr to 300 torr.

[0116] Optionally, the multi-quantum well layer 22 includes alternately grown InGaN quantum well layers and GaN quantum barrier layers. The multi-quantum well layer 22 may include 3 to 8 periods of alternately stacked InGaN quantum well layers and GaN quantum barrier layers.

[0117] When growing the multi-quantum well layer 22, the pressure of the MOCVD reaction chamber is controlled at 200 torr. When growing the InGaN quantum well layer, the temperature of the reaction chamber is 760° C. to 780° C. When growing the GaN quantum barrier layer, the temperature of the reaction chamber is 860° C. to 890° C.

[0118] As an example, in the embodiment of the present disclosure, the multi-quantum well layer 22 includes five periods of alternately stacked InGaN quantum well layers and GaN quantum barrier layers.

[0119] Optionally, the thickness of the multi-quantum well layer 22 may be 150 nm to 200 nm.

[0120] Optionally, the p-type layer is a magnesium-doped p-type GaN layer. The thickness of the p-type GaN layer may be 0.5 μm to 3 μm.

[0121] When growing the p-type GaN layer, the growth pressure of the p-type GaN layer may be 200 Torr to 600 Torr, and the growth temperature of the p-type GaN layer may be 800° C. to 1000° C.

[0122] Step 2: etching the epitaxial layer 20 to form a groove 24 on the surface of the second semiconductor layer 23 to expose the first semiconductor layer 21 .

[0123] Step S12 : forming a transparent conductive layer 30 on the surface of the epitaxial layer 20 .

[0124] like Figure 6 As shown, it may specifically include: forming a transparent conductive layer 30 on the surface of the second semiconductor layer 23 .

[0125] The transparent conductive layer 30 is located outside the groove 24 .

[0126] Exemplarily, the transparent conductive layer 30 is an indium tin oxide layer or an indium zinc oxide layer.

[0127] Exemplarily, the thickness of the transparent conductive layer 30 is 100 angstroms to 300 angstroms. For example, the thickness of the transparent conductive layer 30 is 200 angstroms.

[0128] Step S13 : forming a passivation layer 40 and a second reflective layer 52 on the surface of the epitaxial layer 20 .

[0129] The second reflective layer 52 is located in the passivation layer 40 and between the surface of the passivation layer 40 away from the epitaxial layer 20 and the surface of the passivation layer 40 close to the epitaxial layer 20 , and the passivation layer 40 wraps the transparent conductive layer 30 .

[0130] like Figures 7 to 9 As shown, it may specifically include: first, preparing a passivation layer 40 on the surface of the epitaxial layer 20; then, forming a second reflective layer 52 on the passivation layer 40, and further forming the passivation layer 40 covering the second reflective layer 52 on the second reflective layer 52; then, etching on the surface of the passivation layer 40 to form a through hole exposing the transparent conductive layer 30, and making the through hole avoid the area where the second reflective layer 52 is located.

[0131] Step S14 : forming a first reflective layer 51 and a protective layer 53 on the surface of the passivation layer 40 away from the epitaxial layer 20 .

[0132] Among them, the first reflective layer 51 is connected to the transparent conductive layer 30 through the through hole on the passivation layer 40, the protective layer 53 is located on the surface of the passivation layer 40 away from the epitaxial layer 20, and wraps the first reflective layer 51, and at least part of the orthographic projection of the second reflective layer 52 on the surface of the epitaxial layer 20 away from the passivation layer 40 overlaps with the orthographic projection of the protective layer 53 on the surface of the epitaxial layer 20 away from the passivation layer 40.

[0133] like Fig.10 As shown, it may specifically include: firstly forming a first reflective layer 51 on the surface of the passivation layer 40, so that the first reflective layer 51 is connected to the transparent conductive layer 30 through the through hole on the passivation layer 40. Then, forming a protective layer 53 on the surface of the passivation layer 40 to cover the first reflective layer 51.

[0134] After step S14, the following steps may also be included:

[0135] First, a first insulating layer 41 covering the protective layer 53 is formed on the surface of the passivation layer 40, and the first insulating layer 41 is etched to form a via hole exposing the protective layer 53 and the bottom of the groove 24; then, at least two electrodes 60 are formed on the surface of the first insulating layer 41, a part of the electrode 60 is connected to the first semiconductor layer 21 in the groove 24 through the via hole, and another part of the electrode 60 is connected to the protective layer 53 through the via hole; then, a second insulating layer 42 covering the electrode 60 is formed on the surface of the first insulating layer 41, and the second insulating layer 42 is etched to form a via hole exposing the electrode 60; finally, at least two pads 70 are formed on the surface of the second insulating layer 42, and the at least two pads 70 are respectively connected to different electrodes 60 through the via holes.

[0136] Fig.11 ΔLOP is a luminance ratio comparison diagram of a light emitting diode provided by an embodiment of the present disclosure, wherein ΔLOP is a luminance ratio, which refers to the difference in luminance between different regions or different light sources.

[0137] like Fig.11 As shown, the brightness ratio of the light emitting diode in the related art (see the left side of the figure) is 0, and the brightness ratio of the light emitting diode provided by the embodiment of the present disclosure (see the right side of the figure) is 1.5%. It can be seen that the light emitting diode provided by the embodiment of the present disclosure can effectively improve the brightness of the light emitting diode.

[0138] The above description is only an optional embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A light emitting diode, characterized in that: The light-emitting diode comprises: an epitaxial layer (20), a passivation layer (40), a first reflective layer (51), a second reflective layer (52) and a protective layer (53), wherein the passivation layer (40) is located on the surface of the epitaxial layer (20); The first reflective layer (51) is located on a surface of the passivation layer (40) away from the epitaxial layer (20), the first reflective layer (51) is electrically connected to the epitaxial layer (20) through a through hole on the passivation layer (40), and the protective layer (53) is located on a surface of the passivation layer (40) away from the epitaxial layer (20) and wraps the first reflective layer (51); The second reflective layer (52) is located within the passivation layer (40) and between a surface of the passivation layer (40) that is away from the epitaxial layer (20) and a surface that is close to the epitaxial layer (20); at least a portion of an orthographic projection of the second reflective layer (52) on the surface of the epitaxial layer (20) that is away from the passivation layer (40) overlaps with an orthographic projection of the protective layer (53) on the surface of the epitaxial layer (20) that is away from the passivation layer (40).

2. The light emitting diode according to claim 1, characterized in that: At least part of the orthographic projection of the peripheral edge of the first reflective layer (51) on the surface of the epitaxial layer (20) away from the passivation layer (40) overlaps with the orthographic projection of the second reflective layer (52) on the surface of the epitaxial layer (20) away from the passivation layer (40).

3. The light emitting diode according to claim 1, characterized in that: The protective layer (53) surrounds a portion of the side wall of the first reflective layer (51), and its orthographic projection on the surface of the epitaxial layer (20) away from the passivation layer (40) is located within the orthographic projection of the second reflective layer (52) on the surface of the epitaxial layer (20) away from the passivation layer (40).

4. The light emitting diode according to any one of claims 1 to 3, characterized in that: The epitaxial layer (20) comprises a first semiconductor layer (21), a multi-quantum well layer (22) and a second semiconductor layer (23) which are stacked in sequence, and the second semiconductor layer (23) has a groove (24) exposing the first semiconductor layer (21); The second reflective layer (52) is located on the second semiconductor layer (23) and outside the groove (24); or, The second reflective layer (52) is located on the second semiconductor layer (23), the side wall of the groove (24) and the first semiconductor layer (21).

5. The light emitting diode according to claim 4, characterized in that: The light-emitting diode further comprises an electrode (60), wherein the electrode (60) is at least within the groove (24), and the reflectivity of the electrode (60) is greater than the reflectivity of the protective layer (53).

6. The light emitting diode according to claim 5, characterized in that: The electrode (60) includes at least one of a Cr layer, an Al layer, a Pt layer and a Ti layer.

7. The light emitting diode according to any one of claims 1 to 3, characterized in that: The reflectivity of the second reflective layer (52) is greater than the reflectivity of the protective layer (53), and the reflectivity of the second reflective layer (52) is greater than 60%.

8. The light emitting diode according to any one of claims 1 to 3, characterized in that: The second reflective layer (52) comprises an Ag layer; or, The second reflective layer (52) comprises an adhesion metal layer and an Ag layer, wherein the adhesion metal layer is located on at least one surface of the Ag layer.

9. The light emitting diode according to any one of claims 1 to 3, characterized in that: The ratio of the thickness of the second reflective layer (52) to the thickness of the passivation layer (40) is less than or equal to 0.

8.

10. A method for preparing a light emitting diode, characterized in that: The preparation method comprises: preparing an epitaxial layer; forming a transparent conductive layer on a surface of the epitaxial layer; forming a passivation layer and a second reflective layer on the surface of the epitaxial layer, wherein the second reflective layer is located in the passivation layer and between a surface of the passivation layer away from the epitaxial layer and a surface of the passivation layer close to the epitaxial layer, and the passivation layer wraps the transparent conductive layer; A first reflective layer and a protective layer are formed on a surface of the passivation layer away from the epitaxial layer, the first reflective layer is connected to the transparent conductive layer through a through hole on the passivation layer, the protective layer is located on a surface of the passivation layer away from the epitaxial layer and wraps the first reflective layer, and at least a portion of an orthographic projection of the second reflective layer on the surface of the epitaxial layer away from the passivation layer overlaps with an orthographic projection of the protective layer on the surface of the epitaxial layer away from the passivation layer.

Images