LED chip and preparation method thereof

Abstract

The present invention provides an LED chip and a method for manufacturing the same. The LED chip comprises an epitaxial light-emitting structure and an electrode structure, the electrode structure comprising a metal reflective layer disposed on the epitaxial light-emitting structure, the metal reflective layer comprising a first reflective layer comprising a first structural layer and a second structural layer stacked together, the grain orientations of the first structural layer and the second structural layer being symmetrically arranged such that the grain boundaries of the first structural layer and the second structural layer in the first reflective layer are perpendicular to the direction of the current flowing through the conductor. By configuring the metal reflective layer in the electrode structure to comprise the first structural layer and the second structural layer, and by controlling the symmetrical orientation of the grains of the first structural layer and the second structural layer, the grain boundaries of the first structural layer and the second structural layer in the first reflective layer are perpendicular to the direction of the current flowing through the conductor, thereby effectively reducing electromigration occurring at the grain boundaries and interfaces and effectively extending the service life of the LED.

Description

Technical Field

[0001] The present invention relates to the technical field of LED chips, and in particular to an LED chip and a preparation method thereof. Background Art

[0002] To reduce light absorption by the electrodes, most LED chips often have a reflective coating on the electrodes. Existing electrode emitting materials are typically aluminum, silver, and other materials. Electromigration is a phenomenon in which matter is transported under the influence of an electric field and temperature. From a microscopic perspective, electromigration is similar to the diffusion of atoms in a crystal, resulting in mass transfer.

[0003] In existing technologies, reflective electrodes containing aluminum or silver as the reflective layer improve chip brightness. However, since aluminum is a very active metal, it is prone to electromigration under the action of electric current, causing the aluminum metal wire to eventually fail and reducing the reliability of the chip. Silver will also undergo electromigration under specific environments such as high temperature and high humidity, resulting in degradation of chip performance. Summary of the Invention

[0004] The present invention aims to provide an LED chip and a method for manufacturing the same, aiming to solve the technical problem in the prior art that reflective electrode materials are prone to electromigration.

[0005] In order to achieve the above object, the present invention is implemented through the following technical solution: an LED chip, comprising:

[0006] Epitaxial light-emitting structure;

[0007] An electrode structure, wherein the electrode structure includes a metal reflective layer arranged on the epitaxial light-emitting structure, the metal reflective layer includes a first reflective layer, the first reflective layer includes a first structural layer and a second structural layer stacked together, and the grain orientations of the first structural layer and the second structural layer are symmetrically arranged so that the grain boundaries of the first structural layer and the second structural layer are perpendicular to the direction of the wire current.

[0008] Compared with the prior art, the beneficial effect of the present invention lies in: by setting the metal reflective layer in the electrode structure to a first reflective layer including a first structure layer and a second structure layer, and by controlling the symmetrical arrangement of the grain orientations of the first structure layer and the second structure layer, the grain boundaries of the first structure layer and the second structure layer in the first reflective layer are perpendicular to the direction of the wire current, thereby effectively improving the electromigration generated at the grain boundaries and interfaces, and effectively improving the service life of the LED.

[0009] According to one aspect of the above technical solution, the metal reflective layer further includes a second reflective layer, and the second reflective layer and the first reflective layer are sequentially stacked on the epitaxial light-emitting structure.

[0010] According to one aspect of the above technical solution, the metal reflective layer includes a plurality of first reflective layers and second reflective layers that are alternately stacked, wherein the layer of the metal reflective layer closest to the epitaxial light-emitting structure is the second reflective layer.

[0011] According to one aspect of the above technical solution, the electrode structure further includes a metal barrier layer, and the metal barrier layer and the metal reflective layer are sequentially stacked on the epitaxial light-emitting structure.

[0012] According to one aspect of the above technical solution, the electrode structure further includes a conductive layer provided on the metal reflective layer.

[0013] According to one aspect of the above technical solution, the conductive layer includes a first conductive sublayer, a second conductive sublayer, a third conductive sublayer, a fourth conductive sublayer, a fifth conductive sublayer and a sixth conductive sublayer sequentially stacked on the metal reflective layer.

[0014] On the other hand, the present invention also provides a method for preparing an LED chip, comprising the following steps:

[0015] preparing an epitaxial light-emitting structure;

[0016] preparing an electrode structure including a metal reflective layer on the epitaxial light-emitting structure, wherein the metal reflective layer includes a first reflective layer, and the first reflective layer includes a first structural layer and a second structural layer stacked together;

[0017] The steps of preparing the first reflective layer specifically include:

[0018] forming the first structure layer on the epitaxial light-emitting structure using a first evaporation process, wherein the first evaporation process includes: controlling an angle between an evaporation contact surface of the epitaxial light-emitting structure and an evaporation direction of an evaporation source to be a first preset value, and performing evaporation for a first preset time using a first preset evaporation rate;

[0019] A second evaporation process is used to form the second structural layer on the first structural layer, wherein the second evaporation process includes: controlling the angle between the evaporation contact surface of the first structural layer and the evaporation direction of the evaporation source to be a second preset value, and using a second preset evaporation rate to perform evaporation for a second preset time, and the first preset value and the second preset value are reciprocal numbers of each other.

[0020] According to one aspect of the above technical solution, the metal reflective layer further includes a second reflective layer, and the second reflective layer and the first reflective layer are sequentially stacked on the epitaxial light-emitting structure;

[0021] Before preparing the first reflective layer, a second reflective layer is formed on the epitaxial light-emitting structure using a third evaporation process, wherein the third evaporation process includes: controlling the angle between the evaporation contact surface of the epitaxial light-emitting structure and the evaporation direction of the evaporation source to be a third preset value, and using a third preset evaporation rate to perform evaporation for a third preset time.

[0022] According to one aspect of the above technical solution, the metal reflective layer includes a plurality of first reflective layers and second reflective layers that are alternately stacked, wherein the layer of the metal reflective layer closest to the epitaxial light-emitting structure is the second reflective layer;

[0023] The second reflective layer is prepared by a third evaporation process, wherein the third evaporation process includes: controlling the angle between the evaporation contact surface of the epitaxial light-emitting structure and the evaporation direction of the evaporation source to be a third preset value, and using a third preset evaporation rate to perform evaporation for a third preset time.

[0024] According to one aspect of the above technical solution, the electrode structure further includes a metal barrier layer and a conductive layer, and the metal barrier layer, the metal reflective layer and the conductive layer are sequentially stacked on the extended light structure;

[0025] Before preparing the metal reflective layer, forming a metal barrier layer by evaporation on the epitaxial light-emitting structure;

[0026] After preparing the metal reflective layer, forming a conductive layer on the metal reflective layer by evaporation;

[0027] The conductive layer includes a first conductive sublayer, a second conductive sublayer, a third conductive sublayer, a fourth conductive sublayer, a fifth conductive sublayer and a sixth conductive sublayer sequentially stacked on the metal reflective layer.

[0028] According to one aspect of the above technical solution, the step of preparing the epitaxial light-emitting structure specifically includes:

[0029] providing a substrate;

[0030] Growing an epitaxial layer on the substrate, the epitaxial layer comprising an N-type semiconductor layer, a multi-quantum well active layer, and a P-type semiconductor layer sequentially arranged on the substrate from bottom to top;

[0031] Chip fabrication is performed on the epitaxial layer.

[0032] According to one aspect of the above technical solution, after the step of preparing an electrode structure including a metal reflective layer on the epitaxial light-emitting structure, the method further includes:

[0033] A passivation layer is formed on the chip surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic structural diagram of an LED chip in the first embodiment of the present invention;

[0035] Figure 2 Schematic diagram of the electrode structure in the first embodiment of the present invention;

[0036] Figure 3 A schematic diagram of a portion of the structure of the metal reflective layer in the first embodiment of the present invention;

[0037] Figure 4 A schematic diagram of partial structural operation of an electron beam evaporation machine according to a second embodiment of the present invention;

[0038] Description of main component symbols:

[0039] substrate 11 buffer layer 12 N-type semiconductor layer 13 Multi-quantum well active layer 14 P-type semiconductor layer 15 Current blocking layer 16 Transparent conductive film 17 Epitaxial light-emitting structure 10 Electrode structure 20 passivation layer 30 Metal barrier layer 21 Metal reflective layer 22 First reflective layer 22a Second reflective layer 22b First conductive layer 23 Second conductive layer 24 The third conductive layer 25 Fourth conductive layer 26 Fifth conductive layer 27 Sixth conductive layer 28

[0040] The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0041] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. The drawings illustrate several embodiments of the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present invention.

[0042] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be an intermediate element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used in this specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0044] like Figures 1 to 3 As shown, the first embodiment of the present invention provides an LED chip, including an epitaxial light-emitting structure 10 and an electrode structure 20 disposed on the epitaxial light-emitting structure 10 .

[0045] In this embodiment, the above-mentioned electrode structure 20 includes a metal reflective layer 22 arranged on the epitaxial light-emitting structure 10, and the metal reflective layer 22 includes a first reflective layer 22a composed of a first structural layer and a second structural layer. The grain orientations of the first structural layer and the second structural layer are symmetrically arranged so that the grain boundaries of the first structural layer and the second structural layer in the first reflective layer 22a are perpendicular to the direction of the wire current.

[0046] Preferably, in this embodiment, the metal reflective layer 22 further includes a second reflective layer 22b disposed on one side of the first reflective layer 22a. Furthermore, the metal reflective layer 22 includes a plurality of first reflective layers 22a and second reflective layers 22b, which are alternately stacked. Specifically, in this embodiment, the second reflective layer 22b is a normally disposed single metal layer.

[0047] For ease of understanding, in this embodiment, the partial structure of the metal reflective layer 22 is as follows: Figure 3 As shown in the figure, both the upper and lower ends are the second reflective layer 22b, and the middle part is the above-mentioned first reflective layer 22a, that is, it includes two layers of first structural layer and second structural layer with symmetrical orientation.

[0048] Preferably, in this embodiment, the electrode structure 20 further includes a metal barrier layer 21 disposed between the metal reflective layer 22 and the epitaxial light-emitting structure 10. The metal barrier layer 21 and the metal reflective layer 22 are sequentially stacked on the epitaxial light-emitting structure 10. The metal barrier layer 21 is typically made of Cr and is used to prevent aluminum from migrating to the chip end (epitaxial light-emitting structure 10).

[0049] Preferably, in this embodiment, the electrode structure 20 further includes a conductive layer disposed on the metal reflective layer 22 .

[0050] For ease of understanding, the electrode structure 20 in this embodiment is as follows Figure 2As shown, the metal barrier layer 21 is made of Cr; the metal reflective layer 22 includes a second reflective layer 22b, a first reflective layer 22a, a second reflective layer 22b, a first reflective layer 22a, a second reflective layer 22b, a first reflective layer 22a and a second reflective layer 22b, which are sequentially arranged on the metal barrier layer 21 from bottom to top. The metal reflective layer 22, namely the first reflective layer 22a and the second reflective layer 22b, are both made of Al. In other embodiments of the present application, the first reflective layer 22a and the second reflective layer 22b are Layer 22b may also be made of Ag. The conductive layer includes a first conductive layer 23, a second conductive layer 24, a third conductive layer 25, a fourth conductive layer 26, a fifth conductive layer 27, and a sixth conductive layer 28, stacked sequentially on the metal reflective layer 22 from bottom to top. The first conductive layer 23 is made of Ti, the second conductive layer 24 is made of Ni, the third conductive layer 25 is made of Pt, the fourth conductive layer 26 is made of Ni, the fifth conductive layer 27 is made of Pt, and the sixth conductive layer 28 is made of Au. By way of example and not limitation, the first reflective layer 22a is used to slow down the migration rate of aluminum. The number of first reflective layers 22a provided may be set as needed based on the migration capacity. In other embodiments of the present application, the metal reflective layer 22 may include only a single first reflective layer 22a.

[0051] By way of example and not limitation, in this embodiment, the electrode structure 20 is a Cr / Al / Ti / Ni / Pt / Ni / Pt / Au structure. In other embodiments of the present application, the electrode structure 20 may also be a Cr / Al / Ti / Pt / Ti / Ni / Au structure, or a Cr / Al / Ti / Pt / Au / Pt / Pt / Ti structure, etc.

[0052] Preferably, in this embodiment, the epitaxial light-emitting structure 10 includes a substrate 11, and a buffer layer 12, an N-type semiconductor layer 13, a multi-quantum well active layer 14, and a P-type semiconductor layer 15, which are sequentially arranged on one side of the substrate 11 from bottom to top. Furthermore, in this embodiment, the epitaxial light-emitting structure 10 also includes a current blocking layer 16 arranged on one side of the P-type semiconductor layer 15, and a transparent conductive film 17 arranged on one side of the current blocking layer 16, with the electrode structure 20 being provided on one side of the transparent conductive film 17. The current blocking layer 16 is made of SiO2, and the Cr layer (metal barrier layer 21) is arranged on one side of the epitaxial light-emitting structure 10. Due to the low activity of the transparent conductive film 17, the use of the transparent conductive film 17 made of ITO as an ohmic contact layer can prevent Cr migration.

[0053] In summary, the LED chip in the above-mentioned embodiment of the present invention, by setting the metal reflective layer 22 in the electrode structure 20 to a first reflective layer 22a including a first structure layer and a second structure layer, and at the same time controlling the symmetrical arrangement of the grain orientations of the first structure layer and the second structure layer, makes the grain boundaries of the first structure layer and the second structure layer in the first reflective layer 22a perpendicular to the direction of the wire current, thereby effectively improving the electromigration generated at the grain boundaries and interfaces, and effectively improving the service life of the LED.

[0054] A second embodiment of the present invention provides a method for preparing an LED chip, comprising the following steps:

[0055] Step S100: preparing the epitaxial light emitting structure 10. Specifically, in this embodiment, the above step S100 specifically includes:

[0056] In step S110, a substrate 11 is provided. Substrate 11 can be selected from the group consisting of a sapphire substrate 11, a SiO2 sapphire composite substrate, a silicon substrate, a silicon carbide substrate, a gallium nitride substrate, and a zinc oxide substrate. In this embodiment, sapphire is used as substrate 11. Sapphire is currently the most commonly used substrate material for GaN-based LEDs, and most GaN-based LEDs on the market use sapphire as their substrate material. The greatest advantages of sapphire substrates are mature technology, good stability, and low production costs.

[0057] Step S120: growing an epitaxial layer on the substrate 11. The epitaxial layer includes a buffer layer 12, an N-type semiconductor layer 13, a multi-quantum well active layer 14, and a P-type semiconductor layer 15, which are sequentially arranged on one side of the substrate 11 from bottom to top. Specifically, the epitaxial layer can be grown on the substrate 11 using metal chemical vapor deposition (MOCVD), using high-purity hydrogen as a carrier gas, high-purity ammonia as a nitrogen source, trimethyl gallium and triethyl gallium as gallium sources, trimethyl indium as an indium source, silane as an N-type dopant, trimethyl aluminum as an aluminum source, and dicyclopentadienyl magnesium as a P-type dopant. The N-type semiconductor layer 13 is an n-GaN layer, the P-type semiconductor layer 15 is a p-GaN layer, and the multi-quantum well active layer 14 is a multi-quantum well active layer. The thickness of the n-GaN layer is 1-3 μm, and the Si doping concentration is 5×1018-1×1019 cm -3 The thickness of the p-GaN layer is 200-300 nm, and the Mg doping concentration is 5×1017-1×1020 cm- 3 The molar ratio of In component in the multi-quantum well active layer 14 is 10%-35%.

[0058] Step S130: Chip fabrication is performed on the epitaxial layer. Specifically, the n-GaN morphology is first exposed using ICP etching technology, and then a 300nm thick SiO2 current blocking layer is deposited on the surface using PECVD. Subsequently, an ITO transparent conductive film 17 is deposited using electron beam evaporation technology to ensure uniform current diffusion.

[0059] In step S200 , an electrode structure 20 including a metal reflective layer 22 is prepared on the epitaxial light-emitting structure 10 .

[0060] Preferably, in this embodiment, the steps of preparing the electrode structure 20 including the metal reflective layer 22 on the epitaxial light-emitting structure 10 specifically include:

[0061] In step S210 , a metal barrier layer 21 is formed by evaporation on one side of the epitaxial light emitting structure 10 . In this step, the metal barrier layer 21 is made of Cr to prevent Al particles in the metal reflective layer 22 from migrating to the epitaxial light emitting structure 10 .

[0062] In step S220 , the metal reflective layer 22 is formed on one side of the metal barrier layer 21 by vapor deposition.

[0063] Specifically, in this embodiment, the step of preparing the electrode structure 20 including the metal reflective layer 22 on the epitaxial light-emitting structure 10 specifically includes:

[0064] In step S221, a first structural layer is formed on the epitaxial light-emitting structure 10 using a first evaporation process, wherein the first evaporation process includes: controlling the angle between the evaporation contact surface of the epitaxial light-emitting structure 10 and the evaporation direction of the evaporation source to be a first preset value, and using a first preset evaporation rate to perform evaporation for a first preset time.

[0065] Step S222: Forming a second structural layer on the first structural layer using a second evaporation process. The second structural layer and the second structural layer constitute the first reflective layer 22a. The second evaporation process includes controlling the angle between the evaporation contact surface of the first structural layer and the evaporation direction of the evaporation source to a second preset value, and performing evaporation at a second preset evaporation rate for a second preset time, wherein the first preset value and the second preset value are reciprocal. In this embodiment, the first preset evaporation rate and the second preset evaporation rate are the same, the first preset time and the second preset time are the same, and the first preset value and the second preset value are reciprocal.

[0066] Preferably, in this embodiment, the step of preparing the electrode structure 20 including the metal reflective layer 22 on the epitaxial light-emitting structure 10 further includes:

[0067] In step S223, a third evaporation process is used to form a second reflective layer 22b on one side of the epitaxial light-emitting structure 10, and the second reflective layer 22b and the first reflective layer 22a are sequentially stacked on the epitaxial light-emitting structure, wherein the third evaporation process includes: controlling the angle between the evaporation contact surface of the epitaxial light-emitting structure 10 and the evaporation direction of the evaporation source to be a third preset value, and using a third preset evaporation rate to perform evaporation for a third preset time.

[0068] Preferably, in this embodiment, the metal reflective layer 22 includes a plurality of first reflective layers 22a and second reflective layers 22b that are alternately stacked, wherein the layer of the metal reflective layer 22 closest to the epitaxial light-emitting structure 10 is the second reflective layer 22b. The steps of preparing the plurality of alternately stacked first reflective layers and second reflective layers specifically include:

[0069] Forming a first second reflective layer 22b on the epitaxial light-emitting structure by the third evaporation process;

[0070] The first evaporation process and the second evaporation process are sequentially used to form a first first reflective layer 22a including a first structural layer and a second structural layer on the first second reflective layer 22b;

[0071] Forming a second second reflective layer 22b on the first first reflective layer 22a by using the third evaporation process;

[0072] Sequentially using the first evaporation process and the second evaporation process to form a second first reflective layer 22a on the second second reflective layer 22b;

[0073] Forming a third second reflective layer 22b on the second first reflective layer 22a by the third evaporation process;

[0074] The first evaporation process and the second evaporation process are sequentially used to form a third first reflective layer 22a on the third second reflective layer 22b;

[0075] The fourth second reflective layer 22 b is formed on the third first reflective layer 22 a by using the third evaporation process.

[0076] In this embodiment, the first evaporation process, the second evaporation process and the third evaporation process all adopt electron beam evaporation method, for ease of understanding, Figure 4 The figure shows part of the structure of the electron beam evaporation machine, including a motor, a wafer carrier and an evaporation source emitter. The motor is connected to the wafer carrier to drive the wafer carrier to rotate. The evaporation source emitter is located below the wafer carrier. In conventional evaporation processes, the evaporation surface of the wafer carrier is usually perpendicular to the emission direction of the evaporation source emitter.

[0077] In step S230, a conductive layer is formed by evaporation on one side of the metal reflective layer 22. In this embodiment, the conductive layer includes, from bottom to top, a first conductive layer 23, a second conductive layer 24, a third conductive layer 25, a fourth conductive layer 26, a fifth conductive layer 27, and a sixth conductive layer 28, which are sequentially provided on one side of the metal reflective layer 22. The first conductive layer 23 is made of Ti, the second conductive layer 24 is made of Ni, the third conductive layer 25 is made of Pt, the fourth conductive layer 26 is made of Ni, the fifth conductive layer 27 is made of Pt, and the sixth conductive layer 28 is made of Au.

[0078] Step S300: forming a passivation layer 30 on the surface of the chip. In this step, the passivation layer 30 is a silicon oxide passivation layer 30 with a thickness of 80 nm, which is formed by a PECVD process.

[0079] For ease of understanding, the evaporation process of the metal electrode structure 20 is as follows:

[0080] 1) Preparation of the metal barrier layer 21: The preset evaporation rate of the evaporation source is 0.1 A / s, and Cr is vertically evaporated for 500 seconds;

[0081] 2) Preparation of the metal reflective layer 22: The preset evaporation rate of the evaporation source is 3 A / s.

[0082] (1) First, vertically evaporate Al for 1000 seconds (forming the first second reflective layer 22b), then control the carrier plate to rotate at an angle of 75° to the evaporation source, evaporate for 150 seconds (forming the first structural layer in the first first reflective layer 22a), then control the carrier plate to rotate 90° clockwise to again be at an angle of 75° to the evaporation source, evaporate for 150 seconds (forming the second structural layer in the first first reflective layer 22a), then control the carrier plate to rotate 15° counterclockwise to be perpendicular to the evaporation source, evaporate for 1000 seconds (forming the second second reflective layer 22b);

[0083] (2) the carrier plate is controlled to rotate counterclockwise by 15°, so as to be at 75° with the evaporation source, and the evaporation is carried out for 150 seconds (forming the first structural layer of the second first reflective layer 22a), and then the carrier plate is controlled to rotate clockwise by 90°, so as to be at 75° with the evaporation source again, and the evaporation is carried out for 150 seconds (forming the second structural layer of the second first reflective layer 22a), and then the carrier plate is controlled to rotate counterclockwise by 15°, so as to be perpendicular to the evaporation source, and the evaporation is carried out for 1000 seconds (forming the third second reflective layer 22b);

[0084] (3) the carrier plate is controlled to rotate counterclockwise by 15°, so as to be at 75° with the evaporation source, and the evaporation is carried out for 150 seconds (forming the first structural layer of the third first reflective layer 22a), the carrier plate is controlled to rotate clockwise by 90° again, so as to be at 75° with the evaporation source, and the evaporation is carried out for 150 seconds (forming the second structural layer of the third first reflective layer 22a), and the carrier plate is controlled to rotate counterclockwise by 15° again, so as to be perpendicular to the evaporation source, and the evaporation is carried out for 1000 seconds (forming the fourth second reflective layer 22b);

[0085] 3) Preparation of the first conductive layer 23: The preset evaporation rate of the evaporation source is 2 A / s, and Ti is vertically evaporated for 150 s;

[0086] 4) Preparation of the second conductive layer 24: The preset evaporation rate of the evaporation source is 2 A / s, and Ni is vertically evaporated for 500 s;

[0087] 5) Preparation of the third conductive layer 25: The preset evaporation rate of the evaporation source is 1 A / s, and Pt is vertically evaporated for 850 s;

[0088] 6) Preparation of the fourth conductive layer 26: The preset evaporation rate of the evaporation source is 2 A / s, and Ni is vertically evaporated for 500 s;

[0089] 7) Preparation of the fifth conductive layer 27: The preset evaporation rate of the evaporation source is 1 A / s, and Pt is vertically evaporated for 850 s;

[0090] 8) Preparation of the sixth conductive layer 28: The preset evaporation rate of the evaporation source is 8 A / s, and Au is vertically evaporated for 2500 s.

[0091] In summary, the method for preparing the LED chip in this embodiment forms an inclined oriented film by controlling the metal to be evaporated in a direction at a certain angle to the normal direction of the substrate when preparing the metal reflective layer 22 of the metal electrode, thereby obtaining a symmetrically oriented film layer. This structure is similar to a bamboo joint structure, and the interface is perpendicular to the current direction. This film layer can effectively slow down the migration of aluminum, silver, and other ions, thereby effectively improving the life of the LED chip. In addition, in the prior art, in order to slow down the electromigration phenomenon of reflective materials such as silver and aluminum, various measures can be taken, such as using a composite material electrode structure 20, using copper, chromium, and other additives to alloy it, or using an isolation layer structure to prevent its migration. Whether alloying the reflective material or adding an isolation layer structure, the elemental composition of the electrode structure 20 is changed. In this application, the evaporation source of the first structural layer, the second structural layer, and the second reflective layer 22b can simultaneously use one of the materials such as aluminum and silver. That is, without changing the electrode structure 20, by optimizing the evaporation process, the diffusion of electrodes such as aluminum and silver is effectively prevented.

[0092] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0093] The above-described embodiments merely illustrate several embodiments of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for preparing an LED chip, characterized in that: The method for preparing the LED chip comprises the following steps: preparing an epitaxial light-emitting structure; preparing an electrode structure including a metal reflective layer on the epitaxial light-emitting structure, wherein the metal reflective layer includes a first reflective layer, and the first reflective layer includes a first structural layer and a second structural layer stacked together; The steps of preparing the first reflective layer specifically include: forming the first structure layer on the epitaxial light-emitting structure using a first evaporation process, wherein the first evaporation process includes: controlling an angle between an evaporation contact surface of the epitaxial light-emitting structure and an evaporation direction of an evaporation source to be a first preset value, and performing evaporation for a first preset time using a first preset evaporation rate; A second evaporation process is used to form the second structural layer on the first structural layer, wherein the second evaporation process includes: controlling the angle between the evaporation contact surface of the first structural layer and the evaporation direction of the evaporation source to be a second preset value, and using a second preset evaporation rate to perform evaporation for a second preset time, and the first preset value and the second preset value are reciprocal numbers of each other.

2. The method for preparing an LED chip according to claim 1, wherein: The metal reflective layer further includes a second reflective layer, and the second reflective layer and the first reflective layer are sequentially stacked on the epitaxial light-emitting structure; Before preparing the first reflective layer, a second reflective layer is formed on the epitaxial light-emitting structure using a third evaporation process, wherein the third evaporation process includes: controlling the angle between the evaporation contact surface of the epitaxial light-emitting structure and the evaporation direction of the evaporation source to be a third preset value, and using a third preset evaporation rate to perform evaporation for a third preset time.

3. The method for preparing an LED chip according to claim 1, wherein: The metal reflective layer includes a plurality of first reflective layers and second reflective layers that are alternately stacked, wherein the layer of the metal reflective layer closest to the epitaxial light-emitting structure is the second reflective layer; The second reflective layer is prepared by a third evaporation process, wherein the third evaporation process includes: controlling the angle between the evaporation contact surface of the epitaxial light-emitting structure and the evaporation direction of the evaporation source to be a third preset value, and using a third preset evaporation rate to perform evaporation for a third preset time.

4. The method for preparing an LED chip according to any one of claims 1 to 3, wherein: The electrode structure further includes a metal barrier layer and a conductive layer, wherein the metal barrier layer, the metal reflective layer and the conductive layer are sequentially stacked on the extended light structure; Before preparing the metal reflective layer, forming a metal barrier layer by evaporation on the epitaxial light-emitting structure; After preparing the metal reflective layer, forming a conductive layer on the metal reflective layer by evaporation; The conductive layer includes a first conductive sublayer, a second conductive sublayer, a third conductive sublayer, a fourth conductive sublayer, a fifth conductive sublayer and a sixth conductive sublayer sequentially stacked on the metal reflective layer.

5. An LED chip, characterized in that: The LED chip is prepared by the preparation method according to any one of claims 1 to 4, and the LED chip comprises: Epitaxial light-emitting structure; An electrode structure, wherein the electrode structure includes a metal reflective layer arranged on the epitaxial light-emitting structure, the metal reflective layer includes a first reflective layer, the first reflective layer includes a first structural layer and a second structural layer stacked together, and the grain orientations of the first structural layer and the second structural layer are symmetrically arranged so that the grain boundaries of the first structural layer and the second structural layer are perpendicular to the direction of the wire current.

6. The LED chip according to claim 5, characterized in that The metal reflective layer further includes a second reflective layer, and the second reflective layer and the first reflective layer are sequentially stacked on the epitaxial light-emitting structure.

7. The LED chip according to claim 5, characterized in that The metal reflective layer includes a plurality of first reflective layers and second reflective layers that are alternately stacked, wherein the layer of the metal reflective layer closest to the epitaxial light-emitting structure is the second reflective layer.

8. The LED chip according to any one of claims 5 to 7, characterized in that: The electrode structure further includes a metal barrier layer, and the metal barrier layer and the metal reflective layer are sequentially stacked on the epitaxial light-emitting structure.

9. The LED chip according to any one of claims 5 to 7, characterized in that: The electrode structure further includes a conductive layer disposed on the metal reflective layer.

10. The LED chip according to claim 9, characterized in that: The conductive layer includes a first conductive sublayer, a second conductive sublayer, a third conductive sublayer, a fourth conductive sublayer, a fifth conductive sublayer, and a sixth conductive sublayer sequentially stacked on the metal reflective layer.

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