Light-emitting diode and light-emitting diode preparation method

Abstract

The invention provides a light emitting diode and a light emitting diode preparation method. The light-emitting diode comprises an epitaxial structure, an insulating structure, a first electrode bonding pad and a second electrode bonding pad, the insulating structure covers the epitaxial structure, and a first through hole and a second through hole are formed in the insulating structure; the first electrode bonding pad comprises a first electrode bonding pad filling layer and a first electrode bonding pad welding layer, the second electrode bonding pad comprises a second electrode bonding pad filling layer and a second electrode bonding pad welding layer, the first electrode bonding pad filling layer is located in the first through hole, the second electrode bonding pad filling layer is located in the second through hole, and the second electrode bonding pad welding layer is located in the second through hole. The first electrode bonding pad welding layer covers the first electrode bonding pad filling layer and the surface of the insulation structure around the first through hole, and the second electrode bonding pad welding layer covers the second electrode bonding pad filling layer and the surface of the insulation structure around the second through hole.

Description

Technical Field

[0001] The present disclosure relates to the field of light-emitting devices, and in particular to a light-emitting diode and a method for preparing the light-emitting diode. Background Art

[0002] Light Emitting Diode (LED) is a semiconductor device that can emit light. It has the advantages of energy saving, high brightness, high durability, long life and light weight. It has been widely used in two major fields: backlight display and direct display.

[0003] The related technology provides a light emitting diode, which includes an epitaxial structure, an insulating structure, an electrode structure, etc.

[0004] In the above-mentioned light-emitting diode, since the welding contact area of ​​the electrode structure is small and the heat dissipation capacity is relatively poor, the stability of the light-emitting diode is reduced. Summary of the invention

[0005] The embodiments of the present disclosure provide a light emitting diode and a method for manufacturing the light emitting diode, which can significantly improve the heat dissipation performance of the chip and improve the reliability. The technical solution is as follows:

[0006] In one aspect, a light emitting diode is provided, the light emitting diode comprising:

[0007] An epitaxial structure, an insulating structure, a first electrode pad and a second electrode pad;

[0008] The insulating structure covers the epitaxial structure, and a first through hole and a second through hole are formed in the insulating structure;

[0009] The first electrode pad includes a first electrode pad filling layer and a first electrode pad welding layer, the second electrode pad includes a second electrode pad filling layer and a second electrode pad welding layer, the first electrode pad filling layer is located in the first through hole, the second electrode pad filling layer is located in the second through hole, the first electrode pad welding layer covers the first electrode pad filling layer and the insulating structure surface around the first through hole, and the second electrode pad welding layer covers the second electrode pad filling layer and the insulating structure surface around the second through hole.

[0010] Optionally, the first electrode pad filling layer and the second electrode pad filling layer are stacked layers composed of multiple metals selected from Cr, Ti, Al, Ni, Pt, and Au.

[0011] Optionally, the first electrode pad filling layer and the second electrode pad filling layer are Ti, Al, Ti, Al, Ti, Al, Ti, Al, Ti stacked structures, or the first electrode pad filling layer and the second electrode pad filling layer are Cr, Al, Ti, Al, Ti, Al, Ti, Pt, Ti stacked structures. Optionally, the first electrode pad welding layer and the second electrode pad welding layer are stacked layers composed of multiple metals selected from Cr, Al, AlCu, Ti, Ni, Pt, Au, and AuSn.

[0012] Optionally, the first electrode pad welding layer and the second electrode pad welding layer are a stacked structure of Ti, Ni, Ti, Ni, Ti, Ni, and AuSn.

[0013] Optionally, the insulating structure comprises a first insulating layer and a second insulating layer stacked together, and the first through hole and the second through hole are opened in the second insulating layer;

[0014] The thickness of the first electrode pad filling layer and the second electrode pad filling layer is equal to the thickness of the second insulating layer.

[0015] Optionally, the cross-sections of the first through hole and the second through hole are inverted trapezoids, the cross-sections of the first electrode pad filling layer and the second electrode pad filling layer are regular trapezoids, the first electrode pad welding layer covers the side wall gap between the first through hole and the first electrode pad filling layer, and the second electrode pad welding layer covers the side wall gap between the second through hole and the second electrode pad filling layer.

[0016] In another aspect, a method for preparing a light emitting diode comprises:

[0017] Fabricating epitaxial structures;

[0018] Manufacturing an insulating structure, wherein the insulating structure covers the epitaxial structure, and a first through hole and a second through hole are formed in the insulating structure;

[0019] A first electrode pad and a second electrode pad are manufactured, wherein the first electrode pad includes a first electrode pad filling layer and a first electrode pad welding layer, and the second electrode pad includes a second electrode pad filling layer and a second electrode pad welding layer, the first electrode pad filling layer is located in the first through hole, the second electrode pad filling layer is located in the second through hole, the first electrode pad welding layer covers the first electrode pad filling layer and the insulating structure surface around the first through hole, and the second electrode pad welding layer covers the second electrode pad filling layer and the insulating structure surface around the second through hole.

[0020] Optionally, the manufacturing of the first electrode pad and the second electrode pad includes:

[0021] Making a first mask pattern on the insulating structure, wherein the first mask pattern exposes the first through hole and the second through hole;

[0022] Under the cover of the first mask pattern, the first electrode pad filling layer and the second electrode pad filling layer are respectively formed in the first through hole and the second through hole by a metal evaporation process;

[0023] Making a second mask pattern, wherein the second mask pattern exposes the first through hole and the surrounding set area, and the second through hole and the surrounding set area;

[0024] Under the shielding of the second mask pattern, the first electrode pad welding layer and the second electrode pad welding layer are respectively manufactured on the first electrode pad filling layer and the second electrode pad filling layer by a metal evaporation process.

[0025] Optionally, the first electrode pad filling layer and the second electrode pad filling layer are stacked layers composed of multiple metals selected from Cr, Ti, Al, Ni, Pt, and Au.

[0026] The technical solution provided by the embodiments of the present disclosure has the following beneficial effects:

[0027] In the embodiment of the present disclosure, an electrode pad filling layer is firstly arranged in the through hole of the insulating structure to fill the through hole, and then an electrode pad welding layer is arranged. The electrode pad welding layer covers the electrode pad filling layer and the insulating layer within a certain range around the through hole, so that the electrode pad has a larger flat surface area for welding, thereby improving the heat dissipation capacity of the chip, reducing thermal resistance, and at the same time strengthening the firmness of the welding between the chip and the substrate, thereby improving the stability of the light-emitting diode. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] 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.

[0029] Figure 1 A schematic diagram of the structure of a light emitting diode provided in an embodiment of the present disclosure;

[0030] Figure 2 A top view of the structure of a light emitting diode provided by an embodiment of the present disclosure;

[0031] Figure 3 A flow chart of a method for preparing a light emitting diode provided in an embodiment of the present disclosure;

[0032] Figure 4 A flow chart of another method for preparing a light emitting diode provided in an embodiment of the present disclosure.

[0033] The reference numerals are as follows:

[0034] 10: epitaxial structure; 20: insulating structure;

[0035] 101: substrate; 102: first semiconductor layer; 103: active layer; 104: second semiconductor layer; 105: transparent conductive layer; 106: dielectric film reflective layer; 107: silver mirror layer; 108: first insulating layer; 109: second insulating layer; 110: first electrode; 111: second electrode; 112: first electrode pad filling layer; 113: first electrode pad welding layer; 114: second electrode pad filling layer; 115: second electrode pad welding layer; 116: isolation groove; 117: step structure; 118: first through hole; 119: second through hole; 120: third through hole; 121: fourth through hole;

[0036] 201: a first electrode pad; 202: a second electrode pad. DETAILED DESCRIPTION

[0037] 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.

[0038] The automotive lighting application market usually uses high-power flip-chip LED chips. Since they need to be used for a long time under high current, they have high requirements for the heat dissipation capacity of LED chips. When used for a long time under high current, the thermal effect will become more and more obvious. The accumulation of heat will lead to: first, the junction temperature of the chip will increase, and the excessively high junction temperature will damage the chip; second, it will accelerate aging; third, the luminous efficiency of the LED will decrease and the service life will be shortened. The heat dissipation capacity of the LED chip will be directly related to the high temperature resistance and lifespan. Therefore, improving the heat dissipation capacity of the chip itself and reducing the thermal resistance can effectively reduce the junction temperature of the chip when it is working, avoid excessive heat accumulation, and extend the service life of the LED chip.

[0039] The usual way to improve the heat dissipation capacity of the chip is to increase the effective welding area between the chip electrode and the substrate. The chip electrode area needs to be relatively flat to be effectively welded to the substrate after reflow soldering, but due to the three-dimensional structure of the chip surface, the flat area of ​​the chip surface is relatively small, resulting in a small area for effective welding between the chip electrode and the substrate, which ultimately leads to relatively poor heat dissipation capacity.

[0040] Figure 1 A schematic diagram of the structure of a light emitting diode provided by an embodiment of the present disclosure. Figure 1The light emitting diode includes: an epitaxial structure 10 , an insulating structure 20 , a first electrode pad 201 and a second electrode pad 202 .

[0041] Among them, the insulating structure 20 covers the epitaxial structure 10, and a first through hole 118 and a second through hole 119 are opened on the insulating structure 20; the first electrode pad 201 includes a first electrode pad filling layer 112 and a first electrode pad welding layer 113, and the second electrode pad 202 includes a second electrode pad filling layer 114 and a second electrode pad welding layer 115, the first electrode pad filling layer 112 is located in the first through hole 118, and the second electrode pad filling layer 114 is located in the second through hole 119, the first electrode pad welding layer 113 covers the surface of the insulating structure 20 around the first electrode pad filling layer 112 and the first through hole 118, and the second electrode pad welding layer 115 covers the surface of the insulating structure 20 around the second electrode pad filling layer 114 and the second through hole 119.

[0042] In the embodiment of the present disclosure, an electrode pad filling layer is firstly arranged in the through hole of the insulating structure to fill the through hole, and then an electrode pad welding layer is arranged. The electrode pad welding layer covers the electrode pad filling layer and the insulating layer within a certain range around the through hole, so that the electrode pad has a larger flat surface area for welding, thereby improving the heat dissipation capacity of the chip, reducing thermal resistance, and at the same time strengthening the firmness of the welding between the chip and the substrate, thereby improving the stability of the light-emitting diode.

[0043] In the embodiment of the present disclosure, the first electrode pad filling layer 112 and the second electrode pad filling layer 114 may be a stack of multiple metals including Cr, Ti, Al, Ni, Pt, and Au.

[0044] Among them, Cr has good electrical conductivity and can be used for ohmic contact between electrodes and epitaxial structures. Ti has good viscosity and can enhance adhesion. Al has good reflectivity and can improve the reflectivity of light. Ni has a high melting point and is inactive, so it can be used as a protective layer. Pt is a very corrosion-resistant metal that can protect the underlying material from the effects of a corrosive environment. Au has good electrical conductivity.

[0045] In a possible implementation of the present disclosure, the first electrode pad filling layer 112 and the second electrode pad filling layer 114 may be a metal stacked structure of Ti, Al, Ti, Al, Ti, Al, Ti, Al, Ti.

[0046] In this implementation, Ti is used as an adhesion layer and Al is used as a reflective layer, thereby ensuring the reflective and conductive effects of the electrode pad filling layer.

[0047] In another possible implementation of the present disclosure, the first electrode pad filling layer 112 and the second electrode pad filling layer 114 may be a metal stacked structure of Cr, Al, Ti, Al, Ti, Al, Ti, Pt, and Ti.

[0048] In this implementation, Cr serves as an ohmic contact, Al serves as a reflective layer, Ti serves as an adhesion layer, and Pt serves as a protective layer, thereby ensuring the reflective and conductive effects of the electrode pad filling layer.

[0049] In the embodiment of the present disclosure, the first electrode pad welding layer 113 and the second electrode pad welding layer 115 may be a stack of multiple metals selected from Cr, Al, AlCu, Ti, Ni, Pt, Au, and AuSn.

[0050] Among them, the roles of Cr, Al, Ti, Ni, Pt, and Au are referred to above and will not be described again. AlCu can be an AlCu alloy with an Al content of 10%, which makes the evaporation process more stable, does not generate metal particles, and avoids the rupture of the upper film layer. AuSn can be used as a welding layer and has good stability at high temperatures.

[0051] In the embodiment of the present disclosure, the first electrode pad welding layer 113 and the second electrode pad welding layer 115 may be a stacked structure of Ti, Ni, Ti, Ni, Ti, Ni, and AuSn.

[0052] In this implementation, Ti is used as an adhesion layer, Ni is used as a protective layer, and AuSn is used as a welding layer, which ensures the stability of the electrode pad welding layer and the welding effect.

[0053] In the embodiment of the present disclosure, the insulating structure 20 includes a first insulating layer 108 and a second insulating layer 109 ; a first through hole 118 and a second through hole 119 are opened in the second insulating layer 109 .

[0054] In the embodiment of the present disclosure, the thickness of the first electrode pad filling layer 112 and the second electrode pad filling layer 114 is equal to the thickness of the second insulating layer 109 .

[0055] In this implementation, the thickness of the first electrode pad filling layer 112 and the second electrode pad filling layer 114 is equal to the thickness of the second insulating layer 109. The first electrode pad filling layer 112 and the second electrode pad filling layer 114 can fill the through holes of the insulating layer, and can make the first electrode pad welding layer 113 and the second electrode pad welding layer 115 formed with a thickness smoother, and can cover the through holes and the insulating layer at the same time to form a larger welding surface.

[0056] In the embodiment of the present disclosure, the cross-section of the first through hole 118 and the second through hole 119 is an inverted trapezoid, the cross-section of the first electrode pad filling layer 112 and the second electrode pad filling layer 114 is a trapezoid, the first electrode pad welding layer 113 covers the side wall gap between the first through hole 118 and the first electrode pad filling layer 112, and the second electrode pad welding layer 115 covers the side wall gap between the second through hole 119 and the second electrode pad filling layer 114.

[0057] In this implementation, the through hole is designed to be an inverted trapezoid and the filling layer is set to be a trapezoid, which can be easily manufactured. At this time, the welding layer is used to cover the gap between the through hole and the filling layer, which will only form a very small depression and will not affect the overall flatness of the surface of the welding layer.

[0058] Exemplarily, the epitaxial structure 10 includes a first semiconductor layer 102 , an active layer 103 and a second semiconductor layer 104 .

[0059] like Figure 1 As shown, in the embodiment of the present disclosure, the light emitting diode may further include a substrate 101 , a transparent conductive layer 105 , a dielectric film reflective layer 106 , a silver mirror layer 107 , a first electrode 110 and a second electrode 111 .

[0060] The first semiconductor layer 102, the active layer 103, and the second semiconductor layer 104 are sequentially stacked on the substrate 101. The first semiconductor layer 102, the active layer 103, and the second semiconductor layer 104 are provided with a step structure 117 extending to the first semiconductor layer 102, that is, the step bottom surface of the step structure 117 is located in the first semiconductor layer 102. The first semiconductor layer 102, the active layer 103, and the second semiconductor layer 104 are also provided with an isolation groove 116 extending to the substrate 101, that is, the bottom of the isolation groove 116 is located in the substrate 101.

[0061] The transparent conductive layer 105 , the dielectric film reflective layer 106 , and the silver mirror layer 107 are sequentially stacked on the second semiconductor layer 104 . The dielectric film reflective layer 106 wraps the transparent conductive layer 105 , and the dielectric film reflective layer has a plurality of through holes. The silver mirror layer 107 is connected to the transparent conductive layer 105 through the through holes. The first insulating layer 108 covers the silver mirror layer 107, the isolation groove 116 and the step structure 117. The first insulating layer 108 respectively opens a third through hole 120 and a fourth through hole 121 at the silver mirror layer 107 and the top surface of the step structure 117. The first electrode 110 is connected to the silver mirror layer 107 through the third through hole 120 at the silver mirror layer 107, the second electrode 111 is connected to the first semiconductor layer 102 through the fourth through hole 121 at the bottom surface of the step structure 117, the first electrode pad 201 is connected to the first electrode 110 through the first through hole 118, and the second electrode pad 202 is connected to the second electrode 111 through the second through hole 119.

[0062] In the embodiment of the present disclosure, the substrate 101 may be any one of substrates such as a sapphire substrate, a Si substrate, and a SiC substrate. The embodiment of the present disclosure does not limit the material of the substrate 101.

[0063] Exemplarily, the substrate 101 is a sapphire substrate.

[0064] In the embodiment of the present disclosure, the first semiconductor layer 102 may be an N-type semiconductor layer, and the second semiconductor layer 104 may be a P-type semiconductor layer.

[0065] For example, the first semiconductor layer 102 may be made of N-type GaN material, and the second semiconductor layer 104 may be made of P-type GaN material.

[0066] In other embodiments, the first semiconductor layer 102 may be a P-type semiconductor layer, and the second semiconductor layer 104 may be an N-type semiconductor layer.

[0067] In the embodiment of the present disclosure, the active layer 103 may be a multi-quantum well layer, such as an InGaN / GaN multi-quantum well layer.

[0068] In the embodiment of the present disclosure, the transparent conductive layer 105 may be an indium tin oxide (ITO) layer. ITO has good transparency and conductivity. It allows light to pass through while conducting current to form an electrical connection.

[0069] In the disclosed embodiment, the thickness of the transparent conductive layer 105 may be 170 to 250 angstroms. If the transparent conductive layer is too thick, it will absorb light and reduce the light extraction rate. If the transparent conductive layer is too thin, the current expansion performance will be poor.

[0070] In the embodiment of the present disclosure, the dielectric film reflective layer 106 may be a SiO 2 layer or a stacked layer formed by SiO 2 and Ti 3 O 5 or other combinations thereof.

[0071] Exemplarily, when the dielectric film reflective layer 106 is a single SiO 2 layer, a plasma enhanced chemical vapor deposition (PECVD) device is used to deposit the dielectric film reflective layer.

[0072] Exemplarily, when the dielectric film reflective layer 106 is a stack or other combination of SiO 2 and Ti 3 O 5 , it is prepared by an optical coating machine.

[0073] In the embodiment of the present disclosure, the silver mirror layer 107 can be a combination of one or more metal or alloy layers such as Ag, Ni, Ti, TiW, Al, AlCu, Ti, Ni, Pt, Au, etc., wherein metal Ag is the main structure and plays the role of light reflection and current expansion, and Ni and TiW can prevent the migration and diffusion of metal silver.

[0074] Exemplarily, the silver mirror layer 107 is a stack of Ag, Ni, Ti, TiW, Al, AlCu, Ti, Ni, Pt, and Au.

[0075] In the embodiment of the present disclosure, the first insulating layer 108 may be a distributed Bragg reflector (DBR) layer or a SiO 2 layer, and the DBR layer is a stacked layer formed by SiO 2 and Ti 3 O 5 .

[0076] In the embodiment of the present disclosure, the second insulating layer 109 may be a DBR layer or a SiO 2 layer, and the DBR layer is a stacked layer formed by SiO 2 and Ti 3 O 5 .

[0077] In the embodiment of the present disclosure, the first electrode 110 and the second electrode 111 may be a combination of one or more metal or alloy layers such as Cr, Al, AlCu, Ti, Ni, Pt and Au.

[0078] Exemplarily, the first electrode 110 and the second electrode 111 are stacked layers of Cr, Al, AlCu, Ti, Ni, Pt, and Au.

[0079] It is worth noting that in the embodiments of the present disclosure, structures may be selectively increased or decreased based on the structure of the above-mentioned light emitting diode, and the present disclosure does not impose any limitation on this.

[0080] Figure 2 A top view of the structure of a light emitting diode provided by an embodiment of the present disclosure. Figure 2 The first electrode pad filling layer 112 is located in the first through hole 118, the second electrode pad filling layer 114 is located in the second through hole 119, the first electrode pad welding layer 113 covers the first electrode pad filling layer 112 and its surroundings, and the second electrode pad welding layer 115 covers the second electrode pad filling layer 114 and its surroundings, which effectively increases the welding area and can significantly improve the high temperature resistance of the chip and improve reliability.

[0081] Figure 3 A flow chart of a method for preparing a light emitting diode provided in an embodiment of the present disclosure. Figure 3 The method steps include:

[0082] S11. Fabricating an epitaxial structure.

[0083] S12, manufacturing an insulating structure, wherein the insulating structure covers the epitaxial structure, and a first through hole and a second through hole are formed in the insulating structure.

[0084] S13. Make a first electrode pad and a second electrode pad, the first electrode pad includes a first electrode pad filling layer and a first electrode pad welding layer, the second electrode pad includes a second electrode pad filling layer and a second electrode pad welding layer, the first electrode pad filling layer is located in the first through hole, the second electrode pad filling layer is located in the second through hole, the first electrode pad welding layer covers the first electrode pad filling layer and the insulating structure surface around the first through hole, and the second electrode pad welding layer covers the second electrode pad filling layer and the insulating structure surface around the second through hole.

[0085] In the embodiment of the present disclosure, an electrode pad filling layer is firstly arranged in the through hole of the insulating structure to fill the through hole, and then an electrode pad welding layer is arranged. The electrode pad welding layer covers the electrode pad filling layer and the insulating layer within a certain range around the through hole, so that the electrode pad has a larger flat surface area for welding, thereby improving the heat dissipation capacity of the chip, reducing thermal resistance, and at the same time strengthening the firmness of the welding between the chip and the substrate, thereby improving the stability of the light-emitting diode.

[0086] Figure 4 Another light emitting diode manufacturing method provided by the present disclosure is a flow chart. Figure 4 The method steps include:

[0087] S21. Forming a first semiconductor layer, an active layer, and a second semiconductor layer in sequence on a substrate, wherein the second semiconductor layer, the active layer, and the first semiconductor layer constitute an epitaxial structure.

[0088] The substrate may be any one of a sapphire substrate, a Si substrate, a SiC substrate and the like.

[0089] In one example, step S21 includes:

[0090] The first step is to make the first semiconductor layer.

[0091] In the embodiment of the present disclosure, the first semiconductor layer is N-type GaN.

[0092] The second step is to make the active layer.

[0093] In the embodiment of the present disclosure, the active layer is a multi-quantum well layer, such as an InGaN / GaN multi-quantum well layer.

[0094] The third step is to make the second semiconductor layer.

[0095] In the embodiment of the present disclosure, the second semiconductor layer is P-type GaN.

[0096] In the embodiment of the present disclosure, the first semiconductor layer, the active layer, and the second semiconductor layer are sequentially stacked on the substrate.

[0097] S22, performing graphic processing on the epitaxial structure to form a step structure and an isolation groove, wherein the step structure includes a step bottom surface and a step top surface.

[0098] In the embodiment of the present disclosure, the top surface of the step structure is located in the second semiconductor layer, and the bottom surface of the step structure is located in the first semiconductor layer. The bottom of the isolation trench is located on the substrate surface.

[0099] In the disclosed embodiment, the step structure is etched by ICP.

[0100] S23. Fabricate a transparent conductive layer on the surface of the epitaxial structure.

[0101] In the embodiment of the present disclosure, the transparent conductive layer may be an ITO layer. ITO has excellent transparency and conductivity. It allows light to pass through while also conducting current to form an electrical connection.

[0102] In the disclosed embodiment, the thickness of the transparent conductive layer may be 170 to 250 angstroms. If the transparent conductive layer is too thick, it will absorb light and reduce the light extraction rate. If the transparent conductive layer is too thin, the current expansion performance will be poor.

[0103] S24, manufacturing a dielectric film reflective layer on the surface of the epitaxial structure, wherein the dielectric film reflective layer wraps the transparent conductive layer, and a plurality of through holes are opened on the dielectric film reflective layer.

[0104] In the embodiment of the present disclosure, the dielectric film reflective layer may be a SiO2 layer or a stack or other combination formed by SiO2 and Ti3O5.

[0105] Exemplarily, when the dielectric film reflective layer is a single SiO 2 layer, a plasma enhanced chemical vapor deposition (PECVD) device is used to deposit the dielectric film reflective layer.

[0106] Exemplarily, when the dielectric film reflective layer is a stack or other combination formed by SiO2 and Ti3O5, it is prepared by an optical coating machine.

[0107] In the disclosed embodiments, through holes in the dielectric film reflective layer are fabricated by means of buffered oxide etchant (BOE) etching, inductively coupled plasma etching (ICP) etching, or a combination of ICP etching and BOE etching.

[0108] S25. A silver mirror layer is made on the surface of the dielectric film reflective layer, and the silver mirror layer is connected to the transparent conductive layer through a through hole.

[0109] In the embodiments of the present disclosure, the silver mirror layer can be a combination of one or more metal or alloy layers such as Ag, Ni, Ti, TiW, Al, AlCu, Ti, Ni, Pt, Au, etc., wherein metal Ag is the main structure and plays the role of light reflection and current expansion, and Ni and TiW can prevent the migration and diffusion of metal silver.

[0110] Exemplarily, the silver mirror layer is a stack of Ag, Ni, Ti, TiW, Al, AlCu, Ti, Ni, Pt, and Au.

[0111] S26, making a first insulating layer and opening a third through hole and a fourth through hole, the first insulating layer covering the silver mirror layer, the isolation groove and the step top surface and the step bottom surface of the step structure.

[0112] In the embodiment of the present disclosure, the first insulating layer may be a distributed Bragg reflector DBR layer or a SiO2 layer, and the DBR layer is a stacked layer formed by SiO2 and Ti3O5.

[0113] In the embodiment of the present disclosure, the first insulating layer respectively opens third through holes at the silver mirror layer and at the top surface of the step structure.

[0114] In the embodiment of the present disclosure, the third through hole and the fourth through hole are manufactured by etching or corroding.

[0115] S27, manufacturing a first electrode and a second electrode.

[0116] In the embodiment of the present disclosure, the first electrode and the second electrode may be a combination of one or more metal or alloy layers such as Cr, Al, AlCu, Ti, Ni, Pt and Au.

[0117] Exemplarily, the first electrode and the second electrode are stacked layers of Cr, Al, AlCu, Ti, Ni, Pt and Au.

[0118] S28, making a second insulating layer and opening a first through hole and a second through hole, wherein the second insulating layer covers the first electrode, the second electrode and the first insulating layer.

[0119] In the embodiment of the present disclosure, the second insulating layer may be a distributed Bragg reflector, DBR layer or a SiO2 layer, and the DBR layer is a stacked layer formed by SiO2 and Ti3O5.

[0120] In the embodiment of the present disclosure, the second insulating layer respectively opens a first through hole and a second through hole at the first electrode and the second electrode, the first electrode pad is connected to the first electrode through the first through hole at the first electrode, and the second electrode pad is connected to the second electrode through the second through hole at the second electrode.

[0121] In the embodiment of the present disclosure, the first through hole and the second through hole are manufactured by etching or corroding.

[0122] S29, manufacturing a first electrode pad and a second electrode pad.

[0123] In the embodiment of the present disclosure, step S29 includes:

[0124] In the first step, a first mask pattern is formed on the insulating structure, wherein the first mask pattern exposes the first through hole and the second through hole.

[0125] In the second step, under the cover of the first mask pattern, a first electrode pad filling layer and a second electrode pad filling layer are respectively formed in the first through hole and the second through hole by a metal evaporation process.

[0126] In the embodiment of the present disclosure, the first electrode pad filling layer is located in the first through hole, and the second electrode pad filling layer is located in the second through hole.

[0127] In the embodiment of the present disclosure, the first electrode pad filling layer and the second electrode pad filling layer may be a stack of multiple metals including Cr, Ti, Al, Ni, Pt, and Au.

[0128] Among them, Cr has good electrical conductivity and can be used for ohmic contact between electrodes and epitaxial structures. Ti has good viscosity and can enhance adhesion. Al has good reflectivity and can improve the reflectivity of light. Ni has a high melting point and is inactive, so it can be used as a protective layer. Pt is a very corrosion-resistant metal that can protect the underlying material from the effects of a corrosive environment. Au has good electrical conductivity.

[0129] In a possible implementation of the present disclosure, the first electrode pad filling layer and the second electrode pad filling layer may be a metal stacked structure of Ti, Al, Ti, Al, Ti, Al, Ti, Al, Ti.

[0130] In this implementation, Ti is used as an adhesion layer and Al is used as a reflective layer, thereby ensuring the reflective and conductive effects of the electrode pad filling layer.

[0131] In another possible implementation of the present disclosure, the first electrode pad filling layer and the second electrode pad filling layer may be a metal stacked structure of Cr, Al, Ti, Al, Ti, Al, Ti, Pt, Ti.

[0132] In this implementation, Cr serves as an ohmic contact, Al serves as a reflective layer, Ti serves as an adhesion layer, and Pt serves as a protective layer, thereby ensuring the reflective and conductive effects of the electrode pad filling layer.

[0133] After the metal evaporation process is completed, the first mask pattern and the metal layer on the first mask pattern are removed through a stripping process, and the remaining metal layer in the through hole is used as a pad filling layer.

[0134] The third step is to make a second mask pattern, wherein the second mask pattern exposes the first through hole and the surrounding set area, the second through hole and the surrounding set area.

[0135] In the embodiment of the present disclosure, the thickness of the first electrode pad filling layer and the second electrode pad filling layer is equal to the thickness of the second insulating layer.

[0136] In this implementation, the thickness of the first electrode pad filling layer and the second electrode pad filling layer is equal to the thickness of the second insulating layer. The first electrode pad filling layer and the second electrode pad filling layer can fill the through hole of the insulating layer, and can make the first electrode pad welding layer and the second electrode pad welding layer formed by the thickness smoother, and can cover the through hole and the insulating layer at the same time to form a larger welding surface.

[0137] In the fourth step, under the cover of the second mask pattern, a first electrode pad welding layer and a second electrode pad welding layer are respectively formed on the first electrode pad filling layer and the second electrode pad filling layer by a metal evaporation process.

[0138] In the embodiment of the present disclosure, the first electrode pad welding layer and the second electrode pad welding layer may be a stack of multiple metals selected from Cr, Al, AlCu, Ti, Ni, Pt, Au, and AuSn.

[0139] Among them, the roles of Cr, Al, Ti, Ni, Pt, and Au are referred to above and will not be described again. AlCu can be an AlCu alloy with an Al content of 10%, which makes the evaporation process more stable, does not generate metal particles, and avoids the rupture of the upper film layer. AuSn can be used as a welding layer and has good stability at high temperatures.

[0140] In the embodiment of the present disclosure, the first electrode pad welding layer and the second electrode pad welding layer may be a stacked structure of Ti, Ni, Ti, Ni, Ti, Ni, and AuSn.

[0141] In this implementation, Ti is used as an adhesion layer, Ni is used as a protective layer, and AuSn is used as a welding layer, which ensures the stability of the electrode pad welding layer and the welding effect.

[0142] After the metal evaporation process is completed, the second mask pattern and the metal layer on the second mask pattern are removed through a stripping process, and the remaining metal layer is used as a pad welding layer.

[0143] 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 structure (10), an insulating structure (20), a first electrode pad (201) and a second electrode pad (202); The insulating structure (20) covers the epitaxial structure (10), and a first through hole (118) and a second through hole (119) are provided on the insulating structure (20); The first electrode pad (201) includes a first electrode pad filling layer (112) and a first electrode pad welding layer (113); the second electrode pad (202) includes a second electrode pad filling layer (114) and a second electrode pad welding layer (115); the first electrode pad filling layer (112) is located in the first through hole (118); the second electrode pad filling layer (114) is located in the second through hole (119); the first electrode pad welding layer (113) covers the surface of the insulating structure (20) around the first electrode pad filling layer (112) and the first through hole (118); and the second electrode pad welding layer (115) covers the surface of the insulating structure (20) around the second electrode pad filling layer (114) and the second through hole (119).

2. The light emitting diode according to claim 1, characterized in that: The first electrode pad filling layer (112) and the second electrode pad filling layer (114) are stacked layers composed of multiple metals among Cr, Ti, Al, Ni, Pt and Au.

3. The light emitting diode according to claim 2, characterized in that: The first electrode pad filling layer (112) and the second electrode pad filling layer (114) are a stacked structure of Ti, Al, Ti, Al, Ti, Al, Ti, Al, Ti, or the first electrode pad filling layer (112) and the second electrode pad filling layer (114) are a stacked structure of Cr, Al, Ti, Al, Ti, Al, Ti, Pt, Ti.

4. The light emitting diode according to any one of claims 1 to 3, characterized in that: The first electrode pad welding layer (113) and the second electrode pad welding layer (115) are stacked layers composed of multiple metals selected from Cr, Al, AlCu, Ti, Ni, Pt, Au, and AuSn.

5. The light emitting diode according to claim 4, characterized in that: The first electrode pad welding layer (113) and the second electrode pad welding layer (115) are Ti, Ni, Ti, Ni, Ti, Ni, AuSn stacked layer structures.

6. The light emitting diode according to any one of claims 1 to 3, characterized in that: The insulating structure (20) comprises a first insulating layer (108) and a second insulating layer (109) which are stacked, and the first through hole (118) and the second through hole (119) are opened in the second insulating layer (109); The thickness of the first electrode pad filling layer (112) and the second electrode pad filling layer (114) is equal to the thickness of the second insulating layer (109).

7. The light emitting diode according to any one of claims 1 to 3, characterized in that: The cross-sections of the first through hole (118) and the second through hole (119) are inverted trapezoids, the cross-sections of the first electrode pad filling layer (112) and the second electrode pad filling layer (114) are regular trapezoids, the first electrode pad welding layer (113) covers the side wall gap between the first through hole (118) and the first electrode pad filling layer (112), and the second electrode pad welding layer (115) covers the side wall gap between the second through hole (119) and the second electrode pad filling layer (114).

8. A method for preparing a light emitting diode, characterized in that: The method comprises: fabricating epitaxial structures; Manufacturing an insulating structure, wherein the insulating structure covers the epitaxial structure, and a first through hole and a second through hole are formed in the insulating structure; A first electrode pad and a second electrode pad are manufactured, wherein the first electrode pad includes a first electrode pad filling layer and a first electrode pad welding layer, and the second electrode pad includes a second electrode pad filling layer and a second electrode pad welding layer, the first electrode pad filling layer is located in the first through hole, the second electrode pad filling layer is located in the second through hole, the first electrode pad welding layer covers the first electrode pad filling layer and the insulating structure surface around the first through hole, and the second electrode pad welding layer covers the second electrode pad filling layer and the insulating structure surface around the second through hole.

9. The method for preparing a light emitting diode according to claim 8, characterized in that: The method of manufacturing the first electrode pad and the second electrode pad comprises: Making a first mask pattern on the insulating structure, wherein the first mask pattern exposes the first through hole and the second through hole; Under the cover of the first mask pattern, the first electrode pad filling layer and the second electrode pad filling layer are respectively formed in the first through hole and the second through hole by a metal evaporation process; Making a second mask pattern, wherein the second mask pattern exposes the first through hole and the surrounding set area, and the second through hole and the surrounding set area; Under the shielding of the second mask pattern, the first electrode pad welding layer and the second electrode pad welding layer are respectively manufactured on the first electrode pad filling layer and the second electrode pad filling layer by a metal evaporation process.

10. The method for preparing a light emitting diode according to claim 9, characterized in that: The first electrode pad filling layer and the second electrode pad filling layer are stacked layers composed of multiple metals among Cr, Ti, Al, Ni, Pt, and Au.

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