High reflective LED flip chip and its manufacturing method and packaging structure

Abstract

The present invention provides a high-reflection LED flip chip and a manufacturing method and packaging structure thereof. The present invention reduces the distance between contact electrodes, adds a second transparent insulating layer, and opens welding holes on the second transparent insulating layer so that the welding spacing remains unchanged, which can not only greatly improve the chip's external quantum efficiency, but also reduce the light output from the side and electrode surface, thereby effectively improving the brightness without changing the packaging form. The problem of low light output efficiency caused by the large distance between contact electrodes in the prior art is solved.

Description

Technical Field

[0001] The invention relates to the technical field of light emitting diodes, and in particular to a high-reflective LED flip chip and a manufacturing method and a packaging structure thereof. Background Art

[0002] like Figure 1 As shown, the existing LED flip chip generally includes a transparent substrate 101, an N-type semiconductor 102, an MQW 103, a P-type semiconductor 104, an N-side ohmic contact layer 105 disposed on the N-type semiconductor 102, a P-side ohmic contact layer 106 disposed on the P-type semiconductor 104, an N-type contact electrode 108 electrically connected to the N-side ohmic contact layer 105, a P-type contact electrode 109 electrically connected to the P-side ohmic contact layer 106, and a transparent insulating layer 107 covering the surface of the chip. The manufacturing method includes the following steps: 1. growing an epitaxial layer composed of an N-type semiconductor 102, an MQW 103 and a P-type semiconductor 104 on a transparent substrate 101; 2. etching the epitaxial layer from the P-type semiconductor 104 to the N-type semiconductor 102 by a dry method or a wet method; 3. vapor-depositing N-Metal on the N-type semiconductor 102 as an N-side ohmic contact layer 105, and vapor-depositing P-Metal on the P-type semiconductor 104 as a P-side ohmic contact layer 106; 4. dry-etching the epitaxial layer to the transparent substrate 101 by a dry method or a wet method; 5. covering the entire surface of the chip with a transparent insulating layer 107; 6. dry-etching the transparent insulating layer 107 to the N-side ohmic contact layer 105 and the P-side ohmic contact layer 106 by a dry method or a wet method; 7. arranging an N-type contact electrode 108 and a P-type contact electrode 109 in the areas etched in step 6, respectively.

[0003] like Figure 2 The schematic diagram of the packaging of the above-mentioned LED flip chip is shown, the chip is die-bonded to a bracket 110 with Ag plated on the surface, 111 is Sn paste, and the arrow indicates the emission direction of light.

[0004] However, due to the current limitations of packaging technology, especially when used in the Mini LED or Micro LED fields, there are requirements for the gap between Sn paste and Sn paste, and the distance between the N contact electrode and the P contact electrode of the flip chip product has to be increased to ensure the normal use of the LED chip after the package is powered on. This will cause light leakage between the P and N contact electrodes. After the light emitted from the MQW passes through the N-type semiconductor and the transparent insulating layer, it is reflected back and forth between the surface of the bracket and the chip. The red light band is absorbed by the packaging substrate itself or the bracket, affecting the light output efficiency. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a high-reflection LED flip chip and a manufacturing method and packaging structure thereof, which can effectively improve the light extraction rate without changing the existing packaging form.

[0006] The technical solution adopted by the present invention is:

[0007] A high-reflection LED flip chip comprises: a substrate, a first semiconductor layer, an active layer and a second semiconductor layer stacked in sequence from bottom to top; a first ohmic contact layer arranged on the first semiconductor layer; a second ohmic contact layer arranged on the second semiconductor layer; and a first transparent insulating layer covering the surface of the chip, wherein the first transparent insulating layer has a first through hole penetrating the upper and lower surfaces of the first transparent insulating layer and exposing the first ohmic contact layer at a position corresponding to the first ohmic contact layer, and the first transparent insulating layer has a second through hole penetrating the upper and lower surfaces of the first transparent insulating layer and exposing the second ohmic contact layer at a position corresponding to the second ohmic contact layer; and further comprises a first contact electrode, a second contact electrode and a second transparent insulating layer, wherein the first contact electrode contacts the first ohmic contact layer through the first through hole, and the second contact electrode contacts the second ohmic contact layer through the second through hole, and the first contact electrode and the second contact electrode have a gap; the second transparent insulating layer covers the surfaces of the first contact electrode and the second contact electrode, and the second transparent insulating layer has welding holes penetrating the upper and lower surfaces of the second transparent insulating layer and exposing the first contact electrode and the second contact electrode at positions corresponding to the first contact electrode and the second contact electrode; and the gap between the first contact electrode and the second contact electrode is less than or equal to 30 μm.

[0008] Optionally, a gap between the first contact electrode and the second contact electrode is greater than or equal to 10 um.

[0009] Optionally, the thickness of the second transparent insulating layer is less than 1.5 um.

[0010] Optionally, the distance between the welding holes is greater than or equal to 30 um.

[0011] Optionally, the first contact electrode is disposed on the first transparent insulating layer and on the first ohmic contact layer through the first through hole, and the second contact electrode is disposed on the first transparent insulating layer and on the second ohmic contact layer through the second through hole.

[0012] Optionally, the second transparent insulating layer fills a gap between the first contact electrode and the second contact electrode.

[0013] Another technical solution adopted by the present invention is:

[0014] A method for manufacturing a high-reflective LED flip chip, comprising:

[0015] Growing an epitaxial layer on a substrate, wherein the epitaxial layer comprises a first semiconductor layer, an active layer, and a second semiconductor layer stacked sequentially from bottom to top;

[0016] Etching the upper surface of the epitaxial layer to the first semiconductor layer;

[0017] Disposing a first ohmic contact layer on the first semiconductor layer, and disposing a second ohmic contact layer on the second semiconductor layer;

[0018] Covering the surface of the epitaxial layer with a first transparent insulating layer;

[0019] A first through hole is etched through the upper and lower surfaces of the first transparent insulating layer and exposes the first ohmic contact layer at a position of the first transparent insulating layer corresponding to the first ohmic contact layer, and a second through hole is etched through the upper and lower surfaces of the first transparent insulating layer and exposes the second ohmic contact layer at a position of the first transparent insulating layer corresponding to the second ohmic contact layer;

[0020] A first contact electrode in contact with the first ohmic contact layer is disposed in the first through hole, and a second contact electrode in contact with the second ohmic contact layer is disposed in the second through hole, the first contact electrode and the second contact electrode are spaced apart, and the distance between the first contact electrode and the second contact electrode is less than or equal to 30 um;

[0021] A second transparent insulating layer is covered on the surfaces of the first contact electrode and the second contact electrode;

[0022] Welding holes penetrating the upper and lower surfaces of the second transparent insulating layer and exposing the first contact electrode and the second contact electrode are respectively etched at positions of the second transparent insulating layer corresponding to the first contact electrode and the second contact electrode.

[0023] Optionally, a gap between the first contact electrode and the second contact electrode is greater than or equal to 10 um.

[0024] Optionally, the thickness of the second transparent insulating layer is less than 1.5 um, and the distance between the welding holes is greater than or equal to 30 um.

[0025] Another technical solution adopted by the present invention is:

[0026] A packaging structure of a high-reflection LED flip chip comprises a bracket and the above-mentioned high-reflection LED flip chip, wherein the high-reflection LED flip chip is fixed on the bracket through the welding hole and is electrically connected to the bracket.

[0027] From the above, it can be seen that the present invention reduces the distance between the contact electrodes (the gap between the contact electrodes is less than or equal to 30um), adds a second transparent insulating layer, and opens welding holes on the second transparent insulating layer so that the welding spacing remains unchanged, which can not only greatly improve the chip's external quantum efficiency, but also reduce the light emission from the side and electrode surface, thereby effectively improving the brightness without changing the packaging form. The problem of low light extraction rate caused by the large distance between the contact electrodes in the prior art is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0029] Figure 1 It is a structural schematic diagram of an LED flip chip in the prior art;

[0030] Figure 2 A schematic diagram of LED flip chip packaging in the prior art;

[0031] Figure 3 This is a schematic structural diagram of a high-reflective LED flip chip according to an embodiment of the present invention;

[0032] Figure 4 This is a schematic diagram of the packaging structure of a high-reflective LED flip chip according to an embodiment of the present invention;

[0033] Figure 5 It is a brightness experiment comparison diagram of the existing LED flip chip and the high-reflection LED flip chip of the present invention. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Embodiment 1

[0036] like Figure 3As shown, this embodiment provides a high-reflection LED flip chip 2, including: a substrate 201, a first semiconductor layer 202, an active layer 203 and a second semiconductor layer 204 stacked in sequence from bottom to top; a first ohmic contact layer 205 provided on the first semiconductor layer 202; a second ohmic contact layer 206 provided on the second semiconductor layer 204; and a first transparent insulating layer 207 covering the surface of the chip, wherein the first transparent insulating layer 207 has a first through hole penetrating the upper and lower surfaces of the first transparent insulating layer 207 and exposing the first ohmic contact layer 205 at a position corresponding to the first ohmic contact layer 205, and the first transparent insulating layer 207 has a second through hole penetrating the upper and lower surfaces of the first transparent insulating layer 207 and exposing the second ohmic contact layer 206 at a position corresponding to the second ohmic contact layer 206; and also includes a first contact electrode 208, a second contact electrode 209 and a second transparent insulating layer 210, wherein the first transparent insulating layer 207 has a first through hole penetrating the upper and lower surfaces of the first transparent insulating layer 207 and exposing the second ohmic contact layer 206. A contact electrode 208 contacts the first ohmic contact layer 205 through the first through hole, and the second contact electrode 209 contacts the second ohmic contact layer 206 through the second through hole, and the first contact electrode 208 and the second contact electrode 209 have a gap d; the second transparent insulating layer 210 covers the surface of the first contact electrode 208 and the second contact electrode 209 and fills the gap d between the first contact electrode 208 and the second contact electrode 209, and the second transparent insulating layer 210 has welding holes 211 that penetrate the upper and lower surfaces of the second transparent insulating layer 210 and expose the first contact electrode 208 and the second contact electrode 209 at positions corresponding to the first contact electrode 208 and the second contact electrode 209; the gap d between the first contact electrode 208 and the second contact electrode 209 is less than or equal to 30um; the distance between each of the welding holes 111 is greater than or equal to 30um.

[0037] The above-mentioned substrate 201 is a transparent substrate, the above-mentioned first semiconductor layer 202, the first ohmic contact layer 205 and the first contact electrode 208 refer to an N-type semiconductor layer, an N-type ohmic contact layer and an N-type contact electrode respectively, and the above-mentioned second semiconductor layer 204, the second ohmic contact layer 206 and the second contact electrode 209 refer to a P-type semiconductor layer, a P-type ohmic contact layer and a P-type electrode respectively.

[0038] The materials of the first transparent insulating layer 207 and the second transparent insulating layer 210 may be the same or different, and may be oxides or fluorides such as SiOx, SiNx, MgF2, Al2O3, Ti3O5, etc. The materials of the first contact electrode 208 and the second contact electrode 209 may be metals such as Ti, Ni, Au, Al, Cr, Ag, etc.

[0039] It should be noted that the second transparent insulating layer fills the gap between the first contact electrode and the second contact electrode to better achieve N and P isolation.

[0040] In a preferred configuration, the gap d between the first contact electrode 208 and the second contact electrode 209 is greater than or equal to 10 um.

[0041] In another preferred configuration, the first contact electrode 208 is disposed on the first transparent insulating layer 207 and on the first ohmic contact layer 205 through the first through hole, and the second contact electrode 209 is disposed on the first transparent insulating layer 207 and on the second ohmic contact layer 206 through the second through hole. In this configuration, the contact electrode is made as large as possible, and the gap between the contact electrodes is made as small as possible to maximize the light extraction efficiency.

[0042] In another preferred configuration, the thickness of the second transparent insulating layer 210 is less than 1.5 um.

[0043] Embodiment 2

[0044] like Figure 4 As shown, this embodiment provides a packaging structure of a high-reflection LED flip chip, including a bracket 3 and the high-reflection LED flip chip 2 described in the first embodiment, wherein the high-reflection LED flip chip 2 is fixed to the bracket 3 through the welding hole and is electrically connected to the bracket 3. Specifically, the bracket 3 may be made of a material such as Ag plated on the surface, and the welding hole of the high-reflection LED flip chip 2 is fixed to the bracket 3 through a connector 4, such as being welded to the bracket by solder paste.

[0045] Embodiment 3

[0046] This embodiment provides a method for manufacturing a high-reflection LED flip chip, which is used to manufacture the high-reflection LED flip chip described in the first embodiment, and includes the following steps:

[0047] S1, growing an epitaxial layer on a substrate, wherein the epitaxial layer comprises a first semiconductor layer, an active layer, and a second semiconductor layer stacked sequentially from bottom to top;

[0048] S2, etching the upper surface of the epitaxial layer to the first semiconductor layer;

[0049] S3, vapor-depositing N-Metal on the first semiconductor layer as a first ohmic contact layer, and vapor-depositing P-Metal on the second semiconductor layer as a second ohmic contact layer;

[0050] S4, covering the surface of the epitaxial layer with a first transparent insulating layer, the material of which may be a transparent insulating oxide or fluoride such as SiOx, SiNx, MgF2, Al2O3, Ti3O5, etc.;

[0051] S5, etching a first through hole penetrating the upper and lower surfaces of the first transparent insulating layer and exposing the first ohmic contact layer at a position of the first transparent insulating layer corresponding to the first ohmic contact layer, and etching a second through hole penetrating the upper and lower surfaces of the first transparent insulating layer and exposing the second ohmic contact layer at a position of the first transparent insulating layer corresponding to the second ohmic contact layer;

[0052] S6. A first contact electrode in contact with the first ohmic contact layer is provided in the first through hole, and a second contact electrode in contact with the second ohmic contact layer is provided in the second through hole, wherein the first contact electrode and the second contact electrode are provided at a distance, and the distance between the first contact electrode and the second contact electrode is greater than or equal to 10 um and less than or equal to 30 um; the material of the first contact electrode and the second contact electrode may be a metal such as Ti, Ni, Au, Al, Cr, Ag, etc.;

[0053] S7, covering the surfaces of the first contact electrode and the second contact electrode with a second transparent insulating layer, the material of which may be a transparent insulating oxide or fluoride such as SiOx, SiNx, MgF2, Al2O3, Ti3O5, etc.; the thickness of the second transparent insulating layer 210 is less than 1.5um; the first contact electrode and the second contact electrode are isolated by the first transparent insulating layer and the second transparent insulating layer to prevent leakage of the contact electrodes;

[0054] S8. Etch welding holes that penetrate the upper and lower surfaces of the second transparent insulating layer and expose the first contact electrode and the second contact electrode at positions of the second transparent insulating layer corresponding to the first contact electrode and the second contact electrode, respectively, and the distance between each welding hole is greater than or equal to 30 um.

[0055] The etching may be performed by dry etching or wet etching, and the first transparent insulating layer or the second transparent insulating layer may be formed by electron beam evaporation or PECVD deposition.

[0056] After S8, the high-reflection LED flip chip is die-bonded onto the bracket to obtain the packaging structure of the second embodiment.

[0057] In order to ensure the working performance of existing Mini LED or Micro LED flip-chip products after power-on, the gap between the contact electrodes is usually about 80um. However, the present invention reduces the gap between the contact electrodes to 10um-30um, enlarges the contact electrodes, and adds a second transparent insulating layer. A welding hole is opened on the second transparent insulating layer to improve the internal quantum efficiency, reduce the light leakage on the side and electrode side, maximize the light extraction rate, and thus improve the brightness without changing the packaging form. Figure 2 and Figure 4, where the arrow indicates the emitting direction of the light. Obviously, by using the high-reflection LED flip chip of the present invention, the reflection of light between the chip and the bracket in the packaging structure can be basically eliminated. Figure 5 The figure shows the brightness comparison of the existing LED flip chip and the high-reflection LED flip chip of the present invention (several chips are randomly selected), where the horizontal axis represents the chip number and the vertical axis represents the brightness. Figure 5 It can be seen that the brightness of the existing LED flip chip is basically 50-60mcd, while the brightness of the LED flip chip of the present invention can reach 70-80mcd, an average increase of 30%, and the improvement effect is significant.

[0058] In summary, the present invention effectively solves the problem of the existing structure in which the PN contact electrode is far away and affects the light extraction efficiency, and effectively improves the external quantum efficiency and the luminous brightness without changing the existing packaging form.

[0059] It can be understood that the orientation or position relationship indicated by "upper" and "lower" etc. described in the present invention is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the above terms cannot be understood as limiting the present invention.

[0060] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0061] 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 high reflective LED flip chip, comprising: A substrate, a first semiconductor layer, an active layer and a second semiconductor layer stacked sequentially from bottom to top; a first ohmic contact layer disposed on the first semiconductor layer; a second ohmic contact layer disposed on the second semiconductor layer; and a first transparent insulating layer covering the surface of the chip, wherein the first transparent insulating layer has a first through hole penetrating the upper and lower surfaces of the first transparent insulating layer and exposing the first ohmic contact layer at a position corresponding to the first ohmic contact layer, and the first transparent insulating layer has a second through hole penetrating the upper and lower surfaces of the first transparent insulating layer and exposing the second ohmic contact layer at a position corresponding to the second ohmic contact layer; characterized in that it also includes a first contact electrode, a second contact electrode and a second transparent insulating layer, the first contact electrode contacts the first ohmic contact layer through the first through hole, the second contact electrode contacts the second ohmic contact layer through the second through hole, and there is a gap between the first contact electrode and the second contact electrode; the second transparent insulating layer covers the surfaces of the first contact electrode and the second contact electrode, and the second transparent insulating layer has welding holes penetrating the upper and lower surfaces of the second transparent insulating layer and exposing the first contact electrode and the second contact electrode at positions corresponding to the first contact electrode and the second contact electrode; the gap between the first contact electrode and the second contact electrode is less than or equal to 30um; Wherein, the thickness of the second transparent insulating layer is less than 1.5um; The second transparent insulating layer fills a gap between the first contact electrode and the second contact electrode.

2. The high reflective LED flip chip according to claim 1, characterized in that: A gap between the first contact electrode and the second contact electrode is greater than or equal to 10 um.

3. The high reflective LED flip chip according to claim 1, characterized in that: The distance between the welding holes is greater than or equal to 30um.

4. The high reflective LED flip chip according to claim 1, characterized in that: The first contact electrode is disposed on the first transparent insulating layer and on the first ohmic contact layer through the first through hole, and the second contact electrode is disposed on the first transparent insulating layer and on the second ohmic contact layer through the second through hole.

5. A method for manufacturing a high-reflection LED flip chip, characterized in that: include: Growing an epitaxial layer on a substrate, wherein the epitaxial layer comprises a first semiconductor layer, an active layer, and a second semiconductor layer stacked sequentially from bottom to top; Etching the upper surface of the epitaxial layer to the first semiconductor layer; Disposing a first ohmic contact layer on the first semiconductor layer, and disposing a second ohmic contact layer on the second semiconductor layer; Covering the surface of the epitaxial layer with a first transparent insulating layer; A first through hole is etched through the upper and lower surfaces of the first transparent insulating layer and exposes the first ohmic contact layer at a position of the first transparent insulating layer corresponding to the first ohmic contact layer, and a second through hole is etched through the upper and lower surfaces of the first transparent insulating layer and exposes the second ohmic contact layer at a position of the first transparent insulating layer corresponding to the second ohmic contact layer; A first contact electrode in contact with the first ohmic contact layer is disposed in the first through hole, and a second contact electrode in contact with the second ohmic contact layer is disposed in the second through hole, and the first contact electrode and the second contact electrode are spaced apart from each other, and the distance between the first contact electrode and the second contact electrode is less than or equal to 30 um; A second transparent insulating layer is covered on the surfaces of the first contact electrode and the second contact electrode; Welding holes penetrating the upper and lower surfaces of the second transparent insulating layer and exposing the first contact electrode and the second contact electrode are respectively etched at positions of the second transparent insulating layer corresponding to the first contact electrode and the second contact electrode.

6. The method for manufacturing a high-reflection LED flip chip according to claim 5, characterized in that: A gap between the first contact electrode and the second contact electrode is greater than or equal to 10 um.

7. The method for manufacturing a high-reflection LED flip chip according to claim 5, characterized in that: The thickness of the second transparent insulating layer is less than 1.5 um, and the distance between the welding holes is greater than or equal to 30 um.

8. A highly reflective LED flip chip packaging structure, characterized in that: It comprises a bracket and the high-reflection LED flip chip according to any one of claims 1 to 4, wherein the high-reflection LED flip chip is fixed on the bracket through the welding hole and is electrically connected to the bracket.

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