Flip LED chip and preparation method and equipment thereof

Abstract

The invention provides a flip LED chip and a preparation method and equipment thereof, and relates to the technical field of semiconductors. A stacked film layer is arranged on the side, away from the substrate, of the DBR layer, the stacked film layer comprises N first film layers which are sequentially stacked in the first direction, N is larger than or equal to 2, and N is a positive integer; wherein the refractive index of the ith first film layer is larger than that of the (i + 1) th first film layer, N > i > = 1, and i is a positive integer. In other words, the N first film layers with the refractive indexes gradually reduced are arranged on the DBR layer, so that light is reflected and transmitted for multiple times when passing through an internal interface, the reflection effect on internal light is further enhanced, the situation that reflection of the DBR layer is poor under the condition of large-angle glancing is improved, and the reflection performance of the DBR layer on large-angle incident light is improved.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a flip-chip LED chip and a preparation method and equipment thereof. Background Art

[0002] Gallium nitride-based light emitting diodes (LEDs) have become a new generation of lighting sources due to their high light efficiency and environmental friendliness, and are widely used in fields such as lighting, display, backlighting, and optical communications. Among them, flip-chip LED chips have advantages over the currently widely used upright LED chips, such as no need for wire bonding, good brightness and reliability under high current drive, and have become a new research hotspot in the LED field.

[0003] The commonly used flip-chip LED chips currently use a flip-chip process that combines an ITO layer with a DBR (Distributed Bragg Reflector) layer to emit light from a sapphire substrate. However, the DBR layer in the current flip-chip LED chip only has a high reflectivity for light incident in a vertical direction, and has poor reflectivity for light incident at a large angle. Summary of the invention

[0004] In view of the above problems, the present application provides a flip-chip LED chip and a method and device for preparing the same, which improves the reflective performance of the DBR layer for light incident at a large angle. The specific solution is as follows:

[0005] In a first aspect, the present application provides a flip-chip LED chip, the flip-chip LED chip comprising:

[0006] substrate;

[0007] an epitaxial structure located on one side of the substrate, the epitaxial structure comprising an N-type semiconductor layer, a multi-quantum well layer, and a P-type semiconductor layer stacked in sequence in a first direction; a first groove penetrating at least the P-type semiconductor layer and the multi-quantum well layer, the first groove exposing a portion of the surface of the N-type semiconductor layer; the first direction is perpendicular to the plane of the substrate and points from the substrate to the epitaxial structure;

[0008] a DBR layer located on a side of the epitaxial structure away from the substrate;

[0009] A stacked film layer located on the side of the DBR layer away from the substrate, the stacked film layer includes N first film layers stacked in sequence in the first direction, N≥2, and N is a positive integer; wherein the refractive index of the i-th first film layer is greater than the refractive index of the i+1-th first film layer, N>i≥1, and i is a positive integer.

[0010] Preferably, in the above flip-chip LED chip, the first film layer is a silicon nitride film layer.

[0011] Preferably, in the above flip-chip LED chip, N=3;

[0012] The first silicon nitride film layer has a SiH4 / NH3 flow ratio greater than 260, a refractive index greater than 2.4, and a thickness range of 10nm-20nm;

[0013] The second silicon nitride film layer has a SiH4 / NH3 flow ratio ranging from 160 to 200, a refractive index ranging from 2.1 to 2.2, and a thickness ranging from 40 nm to 60 nm;

[0014] The flow ratio of SiH4 / NH3 of the third silicon nitride film layer is less than 95, the refractive index is less than 2.0, and the thickness ranges from 80nm to 100nm.

[0015] Preferably, in the above flip-chip LED chip, the flip-chip LED chip further comprises:

[0016] an electrode structure located between the DBR layer and the epitaxial structure, the electrode structure comprising a P electrode connected to the P-type semiconductor layer, and an N electrode connected to the N-type semiconductor layer;

[0017] A second groove penetrating the N-layer first film layer and the DBR layer, wherein the second groove exposes a portion of the surface of the P electrode and a portion of the surface of the N electrode;

[0018] A pad structure is located on the side of the N-th first film layer away from the substrate, and the pad structure includes a P pad connected to the P electrode through the second groove, and an N pad connected to the N electrode through the second groove.

[0019] Preferably, in the above flip-chip LED chip, the pad structure includes a Cr metal layer, an Al metal layer or an Al alloy layer, a Ti metal layer, a Pt metal layer, a Ni metal layer or a Ni alloy layer, and an Au metal layer which are sequentially stacked in the first direction.

[0020] Preferably, in the above flip-chip LED chip, the thickness of the Cr metal layer ranges from 10 angstroms to 50 angstroms;

[0021] The thickness of the Al metal layer or the Al alloy layer is in the range of 12000 angstroms to 18000 angstroms;

[0022] The thickness of the Ti metal layer ranges from 500 angstroms to 2000 angstroms;

[0023] The thickness of the Pt metal layer ranges from 1500 angstroms to 3000 angstroms;

[0024] The thickness of the Ni metal layer or the Ni alloy layer ranges from 4000 angstroms to 7000 angstroms;

[0025] The thickness of the Au metal layer ranges from 1000 angstroms to 3000 angstroms.

[0026] Preferably, in the above flip-chip LED chip, the pad structure is an Al metal layer, and the thickness of the Al metal layer is in the range of 14000 angstroms to 24000 angstroms.

[0027] Preferably, in the above flip-chip LED chip, when the pad structure has the Al metal layer, the Al metal layer is divided into multiple sections by alternately depositing at two different plating rates, and the Al metal is subjected to one or more melt source treatments during the alternate deposition.

[0028] A second aspect of the present application provides a method for preparing a flip-chip LED chip, the method for preparing a flip-chip LED chip comprising:

[0029] providing a substrate;

[0030] An epitaxial structure is formed on one side of the substrate, wherein the epitaxial structure includes an N-type semiconductor layer, a multi-quantum well layer, and a P-type semiconductor layer stacked in sequence in a first direction; the first direction is perpendicular to the plane where the substrate is located and points from the substrate to the epitaxial structure;

[0031] forming a first groove at least penetrating the P-type semiconductor layer and the multi-quantum well layer, wherein the first groove exposes a portion of the surface of the N-type semiconductor layer;

[0032] forming a DBR layer on a side of the epitaxial structure facing away from the substrate;

[0033] A stacked film layer is formed on the side of the DBR layer facing away from the substrate, and the stacked film layer includes N first film layers stacked in sequence in the first direction, N≥2, and N is a positive integer; wherein the refractive index of the i-th first film layer is greater than the refractive index of the i+1-th first film layer, N>i≥1, and i is a positive integer.

[0034] A third aspect of the present application provides a device, which includes a lighting device or a display device; the device includes any of the flip-chip LED chips described above.

[0035] By means of the above technical scheme, the present application provides a flip-chip LED chip and a method and device for preparing the same, wherein a stacked film layer is arranged on the side of the DBR layer away from the substrate, wherein the stacked film layer includes N first film layers stacked in sequence in the first direction, N≥2, and N is a positive integer; wherein the refractive index of the i-th first film layer is greater than the refractive index of the i+1-th first film layer, N>i≥1, and i is a positive integer. In other words, N first film layers with gradually decreasing refractive index are arranged on the DBR layer, so that light is reflected and transmitted multiple times when passing through the internal interface, further enhancing the reflection effect on the internal light, thereby improving the poor reflection of the DBR layer under large-angle grazing conditions, and improving the reflection performance of the DBR layer for light incident at large angles. In addition, the N first film layers arranged also have a passivation protection effect on the flip-chip LED chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The above and other features, advantages and aspects of the embodiments of the present disclosure will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. Throughout the accompanying drawings, the same or similar reference numerals represent the same or similar elements. It should be understood that the drawings are schematic and the originals and elements are not necessarily drawn to scale.

[0037] Figure 1 A schematic diagram of the structure of a flip-chip LED chip provided by an embodiment of the present invention;

[0038] Figure 2 A schematic flow chart of a method for preparing a flip-chip LED chip provided by an embodiment of the present invention;

[0039] Figure 3-Figure 8 for Figure 2 Schematic diagram of the partial structure corresponding to the preparation method shown. DETAILED DESCRIPTION

[0040] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application. The terms used in the implementation mode of the present application are only used to explain the specific embodiments of the present application, and are not intended to limit the present application. It is known to those skilled in the art that with the development of technology and the emergence of new scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0041] It should be noted that the directional words appearing in the present invention are based on the relative position relationship shown in the drawings and cannot be used as an absolute limitation to the present application.

[0042] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] refer to Figure 1 , Figure 1The schematic diagram of the structure of a flip-chip LED chip provided by an embodiment of the present invention is as follows: The flip-chip LED chip provided by an embodiment of the present invention comprises: a substrate 11 .

[0044] An epitaxial structure located on one side of the substrate 11, the epitaxial structure comprising an N-type semiconductor layer 12, a multi-quantum well layer 13 and a P-type semiconductor layer 14 stacked in sequence in a first direction X; a first groove that at least penetrates the P-type semiconductor layer 14 and the multi-quantum well layer 13, the first groove exposing a portion of the surface of the N-type semiconductor layer 12; the first direction X is perpendicular to the plane of the substrate 11 and points from the substrate 11 to the epitaxial structure.

[0045] The DBR layer 15 is located on the side of the epitaxial structure away from the substrate 11 .

[0046] The stacked film layer 16 is located on the side of the DBR layer 15 away from the substrate 11, and the stacked film layer 16 includes N first film layers stacked in sequence in the first direction X, N≥2, and N is a positive integer; wherein the refractive index of the i-th first film layer is greater than the refractive index of the i+1-th first film layer, N>i≥1, and i is a positive integer.

[0047] Specifically, in the embodiment of the present invention, the substrate 11 includes but is not limited to a sapphire substrate, the N-type semiconductor layer 12 is an N-type doped semiconductor layer, and the P-type semiconductor layer 14 is a P-type doped semiconductor layer. For example, the N-type semiconductor layer 12 can be an N-type doped GaN layer, and the P-type semiconductor layer 14 can be a P-type doped GaN layer. It should be noted that in the embodiment of the present invention, only the GaN layer is used as an example of the semiconductor layer for explanation. Obviously, the semiconductor layer can also be a semiconductor layer of other semiconductor materials. When the GaN layer is used as the semiconductor layer, the flip-chip LED chip is a GaN-based flip-chip LED chip.

[0048] Among them, the core structure of the LED chip is a PN junction. When a forward bias is applied to the PN junction, electrons flow from the N-type region to the P-type region, and holes flow from the P-type region to the N-type region. These carriers recombine near the PN junction, release energy and generate photons to emit light. The multi-quantum well layer 13 is a key structure in the LED chip, and its function is to improve the recombination efficiency and luminescence efficiency of carriers. The multi-quantum well layer 13 is composed of multiple quantum wells (Quantum Well, referred to as QW) and quantum barriers (Quantum Barrier, referred to as QB) alternating. Usually, the band gap width of the quantum well is smaller than the band gap width of the quantum barrier, which will cause electrons and holes to be confined in the quantum well under the action of an external electric field, thereby increasing the recombination probability of electrons and holes, and thus improving the luminescence efficiency.

[0049] It should be noted that the epitaxial structure provided in the embodiment of the present invention may further include other functional film layers, for example, a buffer layer located between the substrate 11 and the N-type semiconductor layer 12 .

[0050] The flip-chip LED chip provided in the embodiment of the present invention is provided with N first film layers with gradually decreasing refractive index on the DBR layer 15, so that the light is reflected and transmitted multiple times when passing through the internal interface, further enhancing the reflection effect on the internal light, thereby improving the poor reflection of the DBR layer 15 under large-angle grazing conditions, and improving the reflection performance of the DBR layer 15 for light incident at large angles.

[0051] In an optional embodiment of the present invention, the first film layer is a silicon nitride film layer.

[0052] Specifically, in the embodiment of the present invention, compared with the silicon oxide film layer, the silicon nitride film layer as a passivation layer has better stability in a high temperature and high humidity environment, has good barrier properties, can effectively prevent the diffusion of harmful substances such as metal ions, better play a passivation role, and extend the service life of the flip-chip LED chip. In addition, since the N-layer silicon nitride film layer deposited on the DBR layer 15 further enhances the reflection of the internal light, the poor reflection of the DBR layer 15 under large-angle grazing conditions is improved, and the reflection performance of the DBR layer 15 for light incident at large angles is improved.

[0053] Optionally, when N=3; the flow ratio of SiH4 / NH3 of the first silicon nitride film layer is greater than 260, the refractive index is greater than 2.4, and the thickness range is 10nm-20nm; the flow ratio of SiH4 / NH3 of the second silicon nitride film layer is in the range of 160-200, the refractive index range is 2.1-2.2, and the thickness range is 40nm-60nm; the flow ratio of SiH4 / NH3 of the third silicon nitride film layer is less than 95, the refractive index is less than 2.0, and the thickness range is 80nm-100nm; by optimizing and matching these parameters, a better passivation effect can be achieved, and the reflection performance of the DBR layer for light incident at a large angle can be maximized.

[0054] In an optional embodiment of the present invention, the flip-chip LED chip provided by the embodiment of the present invention further includes:

[0055] An electrode structure is located between the DBR layer 15 and the epitaxial structure, wherein the electrode structure includes a P electrode 17 connected to the P-type semiconductor layer 14 and an N electrode 18 connected to the N-type semiconductor layer 12 .

[0056] The second groove penetrates the N-layer first film layer and the DBR layer 15 , and the second groove exposes a portion of the surface of the P electrode 17 and a portion of the surface of the N electrode 18 .

[0057] The pad structure is located on the side of the N-th first film layer away from the substrate 11, and the pad structure includes a P pad 19 connected to the P electrode 17 through the second groove, and an N pad 20 connected to the N electrode 18 through the second groove.

[0058] The transparent conductive layer 21 is located on the side of the P-type semiconductor layer 14 facing the P-electrode 17 . The material of the transparent conductive layer 21 includes but is not limited to ITO material.

[0059] Specifically, compared with the structure without N layers of the first film layer in the embodiment of the present invention, the pad structure is connected to the electrode structure through the groove that penetrates the DBR layer 15. In the embodiment of the present application, N layers of the first film layer are further provided on the DBR layer 15, and the pad structure is connected to the electrode structure through the second groove that penetrates the DBR layer 15 and the N layers of the first film layer; under such a structure, the thickness of the pad structure in the second groove increases with the increase of the depth of the second groove, further enhancing the adhesion of the pad structure, thereby reducing the risk of failure caused by the pad falling off, and improving the stability of the flip-chip LED chip.

[0060] That is to say, the flip-chip LED chips currently used can be applied to general lighting, display and other COB (Chips on Board), SMD (Surface Mounted Devices) and other packaging forms, but for special application products such as flexible filaments, the pad structure of the commonly used flip-chip LED chips will have the phenomenon of pad falling off, causing the flip-chip LED chip to fail and affecting the use of the product. The design of the flip-chip LED chip in the technical solution of this application further enhances the adhesion of the pad structure, thereby reducing the risk of failure caused by pad falling off, improving the stability of the flip-chip LED chip, and can be applied to special application products such as flexible filaments.

[0061] Furthermore, in an optional embodiment of the present invention, the electrode structure and the pad structure may be made of materials with high thermal conductivity to effectively dissipate heat, so as to improve the light efficiency and reliability of the flip-chip LED chip.

[0062] In an optional embodiment of the present invention, the pad structure includes a Cr metal layer, an Al metal layer or an Al alloy layer, a Ti metal layer, a Pt metal layer, a Ni metal layer or a Ni alloy layer, and an Au metal layer stacked in sequence in the first direction X.

[0063] Specifically, in the embodiment of the present invention, the thickness of the Cr metal layer is in the range of 10 angstroms to 50 angstroms. The Cr metal layer can also be replaced by a Ni metal layer, which mainly plays the role of ohmic contact and adhesion.

[0064] The thickness of the Al metal layer or the Al alloy layer ranges from 12000 angstroms to 18000 angstroms. The Al metal layer or the Al alloy layer can also be replaced by an Ag metal layer or an Ag alloy layer, which mainly plays the role of reflecting the light emitted by the flip-chip LED chip.

[0065] The thickness of the Ti metal layer ranges from 500 angstroms to 2000 angstroms, and the thickness of the Pt metal layer ranges from 1500 angstroms to 3000 angstroms. The thermal expansion coefficients of the Ti metal layer and the Pt metal layer are relatively small, and they are mainly used to limit the migration of Al and play a protective role.

[0066] The Ni metal layer or the Ni alloy layer has a thickness ranging from 4000 angstroms to 7000 angstroms, and mainly plays a barrier role to prevent Al and Au from forming an alloy.

[0067] The Au metal layer has a thickness ranging from 1000 angstroms to 3000 angstroms, and mainly plays the role of anti-oxidation and adhesion.

[0068] In other words, in the embodiment of the present application, a Ti metal layer and a Pt metal layer with smaller thermal expansion coefficients are selected and deposited between the Al metal layer and the Ni metal layer in the pad structure. On the one hand, this can slow down the interface peeling and crack formation caused by the accumulation of interface stress due to different degrees of thermal expansion caused by the difference in thermal expansion coefficients between the Al metal layer and the semiconductor material. On the other hand, it can further limit the migration of Al, play a protective role, and improve the poor corrosion resistance of the Al metal layer.

[0069] Furthermore, when the pad structure has the Al metal layer, in order to alleviate the point-like protrusions at the boundary of the film layer that may be generated due to the accumulation of stress when forming a thicker Al metal layer, two different plating rates can be used in the process of evaporating the Al metal layer. The deposition can be divided into multiple stages, and the Al metal can be subjected to one or more molten source treatments during the alternating deposition. For example, a fast and slow plating rate alternating deposition method can be used to divide the deposition into multiple stages, and the Al metal can be subjected to one or more molten source treatments during the alternating deposition, so as to further reduce the occurrence of point-like protrusions in the aluminum layer and mitigate the interface peeling caused by the accumulation of interface stress, thereby stratifying and falling off.

[0070] In an optional embodiment of the present invention, the pad structure is an Al metal layer, and the thickness of the Al metal layer ranges from 14000 angstroms to 24000 angstroms.

[0071] Specifically, in the embodiment of the present invention, a single layer of thick aluminum is used to replace the thin aluminum layer and the periodically staggered titanium aluminum alloy layer as the reflective layer. When the Al metal layer is thicker, there are more sufficient metal bonds between the internal Al atoms, and the Al atoms are bound and are not easy to undergo metal migration.

[0072] Secondly, in order to alleviate the formation of single-layer thick aluminum, which may cause point-like protrusions at the boundary of the film layer due to the accumulation of stress, two different plating rates can be used in the thick aluminum evaporation process, which can be divided into multiple stages, and the Al metal can be subjected to one or more molten source treatments during the alternating deposition. For example, a fast and slow plating rate alternating deposition method can be used, which can be divided into multiple stages, and the Al metal can be subjected to one or more molten source treatments during the alternating deposition, so as to further reduce the occurrence of point-like protrusions in the aluminum layer and slow down the interface peeling caused by the accumulation of interface stress, thereby slowing down the stratification and falling off.

[0073] In general, the technical solution of the present application optimizes the thickness and structure of the pad structure, which can improve the welding strength of the pad structure without changing the type of solder paste and the reflow temperature, so that the pad will not fall off in applications such as flexible filaments, thereby improving the reliability of the flip-chip LED chip.

[0074] Based on the above embodiment of the present invention, another embodiment of the present invention further provides a method for preparing a flip-chip LED chip, referring to Figure 2 , Figure 2 A schematic flow chart of a method for preparing a flip-chip LED chip provided in an embodiment of the present invention. The method for preparing a flip-chip LED chip provided in an embodiment of the present invention comprises:

[0075] S101: Figure 3 As shown, a substrate 11 is provided.

[0076] S102: Figure 4 As shown, an epitaxial structure is formed on one side of the substrate 11, and the epitaxial structure includes an N-type semiconductor layer 12, a multi-quantum well layer 13 and a P-type semiconductor layer 14 stacked in sequence in a first direction X; the first direction X is perpendicular to the plane where the substrate 11 is located, and points from the substrate 11 to the epitaxial structure.

[0077] S103: Figure 5 and Figure 6 As shown, a first groove 22 is formed at least penetrating the P-type semiconductor layer 14 and the multi-quantum well layer 13 , and the first groove 22 exposes a portion of the surface of the N-type semiconductor layer 12 .

[0078] This step includes but is not limited to Figure 4The structure shown in the figure is cleaned, and after the cleaning is completed, a photoresist is evenly coated on the surface of the structure, and the pattern is exposed after exposure and development, and then the position not covered by the photoresist is etched by inductively coupled plasma etching (Inductively Coupled Plasma, referred to as ICP) to form a first groove 22, that is, a step is formed to expose a portion of the surface of the N-type semiconductor layer 12, and the etching depth ranges from 1.2μm to 1.4μm. After the etching is completed, the remaining photoresist is removed; further, an isolation groove 23 is prepared by a deep etching process (Deep Etching, referred to as DE) process, and the depth ranges from 4μm to 5.4μm, as shown in FIG. Figure 5 shown.

[0079] Afterwards, if Figure 6 As shown, a transparent conductive layer 21 is deposited on the surface of the P-type semiconductor layer 14 including but not limited to by magnetron sputtering, and then an electrode structure is formed including but not limited to by evaporation, that is, a P electrode 17 and an N electrode 18 are formed, and the bridging core particles are electrically interconnected.

[0080] S104: Figure 7 As shown, a DBR layer 15 is formed on the side of the epitaxial structure facing away from the substrate 11 .

[0081] In this step, the DBR layer 15 acts as a reflective current blocking layer, and the light incident on the DBR layer 15 is reflected to the substrate 11 surface for emission.

[0082] S105: Figure 8 and Figure 1 As shown, a stacked film layer 16 is formed on the side of the DBR layer 15 away from the substrate 11, and the stacked film layer 16 includes N first film layers stacked in sequence in the first direction X, N≥2, and N is a positive integer; wherein the refractive index of the i-th first film layer is greater than the refractive index of the i+1-th first film layer, N>i≥1, and i is a positive integer.

[0083] In this step, including but not limited to forming a stacked film layer 16 on the side of the DBR layer 15 away from the substrate 11 by PECVD (Plasma Enhanced Chemical Vapor Deposition), and then including but not limited to preparing a second groove 24 penetrating the N-layer first film layer and the DBR layer 15 by ICP etching process, wherein the second groove 24 exposes a part of the surface of the P electrode 17 and a part of the surface of the N electrode 18; then including but not limited to using photoresist to photoetch the shapes of the P pad 19 and the N pad 20 on the surface of the structure, and then including but not limited to using metal evaporation to deposit, so that the pad structure and the electrode structure are connected through the etched second groove 24, and then including but not limited to using a blue film to remove excess metal on the surface of the structure, and then removing the photoresist to complete the preparation of the pad structure.

[0084] Based on the above embodiment of the present invention, a device is provided in another embodiment of the present invention. The device includes a lighting device or a display device; the device includes the flip-chip LED chip described in the above embodiment.

[0085] The above is a detailed introduction to a flip-chip LED chip and its preparation method and equipment provided by the present invention. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for general technicians in this field, according to the idea of ​​the present invention, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

[0086] It should be noted that each embodiment in this specification is described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description.

[0087] It should also be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device that includes a series of elements is inherent to the elements, or also includes elements inherent to these processes, methods, articles or devices. In the absence of further restrictions, the elements defined by the sentence "including a..." do not exclude the presence of other identical elements in the process, method, article or device that includes the elements.

[0088] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A flip-chip LED chip, characterized in that: The flip-chip LED chip comprises: substrate; an epitaxial structure located on one side of the substrate, the epitaxial structure comprising an N-type semiconductor layer, a multi-quantum well layer, and a P-type semiconductor layer stacked in sequence in a first direction; a first groove penetrating at least the P-type semiconductor layer and the multi-quantum well layer, the first groove exposing a portion of the surface of the N-type semiconductor layer; the first direction is perpendicular to the plane of the substrate and points from the substrate to the epitaxial structure; a DBR layer located on a side of the epitaxial structure away from the substrate; A stacked film layer located on the side of the DBR layer away from the substrate, the stacked film layer includes N first film layers stacked in sequence in the first direction, N≥2, and N is a positive integer; wherein the refractive index of the i-th first film layer is greater than the refractive index of the i+1-th first film layer, N>i≥1, and i is a positive integer.

2. The flip-chip LED chip according to claim 1, characterized in that: The first film layer is a silicon nitride film layer.

3. The flip-chip LED chip according to claim 2, characterized in that: N=3； The first silicon nitride film layer has a SiH4 / NH3 flow ratio greater than 260, a refractive index greater than 2.4, and a thickness range of 10nm-20nm; The second silicon nitride film layer has a SiH4 / NH3 flow ratio ranging from 160 to 200, a refractive index ranging from 2.1 to 2.2, and a thickness ranging from 40 nm to 60 nm; The flow ratio of SiH4 / NH3 of the third silicon nitride film layer is less than 95, the refractive index is less than 2.0, and the thickness ranges from 80nm to 100nm.

4. The flip-chip LED chip according to any one of claims 1 to 3, characterized in that: The flip-chip LED chip further comprises: an electrode structure located between the DBR layer and the epitaxial structure, the electrode structure comprising a P electrode connected to the P-type semiconductor layer, and an N electrode connected to the N-type semiconductor layer; A second groove penetrating the N-layer first film layer and the DBR layer, wherein the second groove exposes a portion of the surface of the P electrode and a portion of the surface of the N electrode; A pad structure is located on the side of the N-th first film layer away from the substrate, and the pad structure includes a P pad connected to the P electrode through the second groove, and an N pad connected to the N electrode through the second groove.

5. The flip-chip LED chip according to claim 4, characterized in that: The pad structure includes a Cr metal layer, an Al metal layer or an Al alloy layer, a Ti metal layer, a Pt metal layer, a Ni metal layer or a Ni alloy layer, and an Au metal layer which are sequentially stacked in the first direction.

6. The flip-chip LED chip according to claim 5, characterized in that: The thickness of the Cr metal layer ranges from 10 angstroms to 50 angstroms; The thickness of the Al metal layer or the Al alloy layer is in the range of 12000 angstroms to 18000 angstroms; The thickness of the Ti metal layer ranges from 500 angstroms to 2000 angstroms; The thickness of the Pt metal layer ranges from 1500 angstroms to 3000 angstroms; The thickness of the Ni metal layer or the Ni alloy layer ranges from 4000 angstroms to 7000 angstroms; The thickness of the Au metal layer ranges from 1000 angstroms to 3000 angstroms.

7. The flip-chip LED chip according to claim 4, characterized in that: The pad structure is an Al metal layer, and the thickness of the Al metal layer ranges from 14000 angstroms to 24000 angstroms.

8. The flip-chip LED chip according to claim 5 or 7, characterized in that: When the pad structure has the Al metal layer, the Al metal layer is deposited in multiple sections by alternating deposition with two different plating rates, and the Al metal is subjected to one or more melting source treatments during the alternating deposition.

9. A method for preparing a flip-chip LED chip, characterized in that: The method for preparing the flip-chip LED chip comprises: providing a substrate; An epitaxial structure is formed on one side of the substrate, wherein the epitaxial structure includes an N-type semiconductor layer, a multi-quantum well layer, and a P-type semiconductor layer stacked in sequence in a first direction; the first direction is perpendicular to the plane where the substrate is located and points from the substrate to the epitaxial structure; forming a first groove at least penetrating the P-type semiconductor layer and the multi-quantum well layer, wherein the first groove exposes a portion of the surface of the N-type semiconductor layer; forming a DBR layer on a side of the epitaxial structure facing away from the substrate; A stacked film layer is formed on the side of the DBR layer facing away from the substrate, and the stacked film layer includes N first film layers stacked in sequence in the first direction, N≥2, and N is a positive integer; wherein the refractive index of the i-th first film layer is greater than the refractive index of the i+1-th first film layer, N>i≥1, and i is a positive integer.

10. A device, characterized in that: The device comprises a lighting device or a display device; the device comprises the flip-chip LED chip according to any one of claims 1 to 8.

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