CN217114428U

CN217114428U - Flip LED chip and display panel

Info

Publication number: CN217114428U
Application number: CN202220490564.8U
Authority: CN
Inventors: 苟先华; 张彬彬; 肖峰; 王鹏鹏; 苏财钰
Original assignee: Chongqing Kangjia Photoelectric Technology Research Institute Co Ltd
Current assignee: Chongqing Kangjia Optoelectronic Technology Co ltd
Priority date: 2022-03-03
Filing date: 2022-03-03
Publication date: 2022-08-02
Anticipated expiration: 2032-03-03

Abstract

The utility model relates to a flip-chip LED chip and display panel in the flip-chip LED chip, is provided with ohmic contact layer between P electrode and P type semiconductor layer, utilizes ohmic contact layer can realize the ohmic contact between P electrode and the P type semiconductor layer, promotes the efficiency of flip-chip LED chip with electric energy conversion for the light energy. Meanwhile, the ohmic contact layer comprises two transparent conductive layers and a metal reflecting layer sandwiched between the transparent conductive layers, so that the transparent conductive layers can realize transverse current diffusion, and the light emitting uniformity of the epitaxial layer is improved; the metal reflection layer that the clamp was established between two-layer transparent conducting layer is not only resistivity low, can promote the ohmic contact effect, because its light that sends the epitaxial layer has the reflex action moreover, can prevent that the light of epitaxial layer from setting up face one side and emitting, has reduced the loss that light jetted out from one side at electrode setting face place and caused, has promoted flip-chip LED chip's light-emitting efficiency.

Description

Flip LED chip and display panel

Technical Field

The utility model relates to a LED (Light-Emitting Diode) technical field especially relates to a flip-chip LED chip and display panel.

Background

As a light-emitting device, the LED can efficiently convert electric energy into light energy, can remarkably reduce the loss in the energy conversion process, and is energy-saving and environment-friendly. Meanwhile, the LED has the advantages of fast response speed, long service life and the like, and due to the superior performances, the LED has been widely applied in the fields of illumination, display and the like at present, particularly, in the field of display, the LED is continuously updated and iterated, and now the Mini-LED (Mini LED) era is about to enter, and in the future, the Micro-LED (Micro LED) era, the OLED (Organic Light-Emitting Diode) era and the like are available.

However, the light emitting efficiency of the current LED chip is not high, which results in a poor display effect of the display panel prepared based on the LED chip. Therefore, how to improve the light emitting efficiency of the LED chip is an urgent problem to be solved.

Disclosure of Invention

In view of the above deficiencies of the related art, the present application provides a flip LED chip and a display panel, aiming to solve the problem of low light emitting efficiency of the LED chip.

The application provides a flip-chip LED chip, includes:

the epitaxial layer comprises an N-type semiconductor layer, an active layer and a P-type semiconductor layer which are arranged in sequence;

the ohmic contact layer is arranged on one side of the epitaxial layer, which is far away from the N-type semiconductor layer;

an N electrode electrically connected to the N-type semiconductor layer; and

a P electrode electrically connected to the P-type semiconductor layer through the ohmic contact layer;

the ohmic contact layer comprises two transparent conductive layers and a metal reflecting layer sandwiched between the two transparent conductive layers, and the metal reflecting layer is configured to prevent light emitted by the epitaxial layer from being emitted from the side where the P electrode is located.

Among the above-mentioned flip LED chip, be provided with ohmic contact layer between P electrode and P type semiconductor layer, utilize ohmic contact layer can realize the ohmic contact between P electrode and the P type semiconductor layer, promote flip LED chip with the efficiency of electric energy conversion for the light energy. Meanwhile, the ohmic contact layer comprises two transparent conductive layers and a metal reflecting layer sandwiched between the transparent conductive layers, so that the transparent conductive layers can realize transverse current diffusion, and the light emitting uniformity of the epitaxial layer is improved; the metal reflecting layer clamped between the two transparent conducting layers is low in resistivity, the ohmic contact effect can be improved, light emitted by the epitaxial layer can be prevented from being emitted from one side of the electrode arrangement surface due to the fact that the metal reflecting layer has a reflecting effect on the light emitted by the epitaxial layer, loss caused by emission of the light from one side of the electrode arrangement surface is reduced, and the light emitting efficiency of the flip LED chip is improved.

Optionally, the transparent conductive layer comprises an ITO layer.

The ITO layer is arranged in the flip LED chip and serves as the transparent conducting layer, the ITO layer has the advantages of high hardness, high electronic conductivity, low optical absorption coefficient and the like, and the internal quantum efficiency and the external quantum efficiency of the flip LED chip can be improved.

Optionally, the metal reflective layer comprises at least one of an Au layer, an Ag layer, an Al layer, and a Ti layer.

The metal reflecting layer in the flip LED chip comprises at least one of the Au layer, the Ag layer, the Al layer and the Ti layer, the layers are low in structural resistivity and excellent in reflecting performance, the ohmic contact effect between the P electrode and the P type semiconductor layer can be improved, the quantum efficiency in the epitaxial layer is improved, the unnecessary loss of light is reduced, and the external quantum efficiency of the flip LED chip is improved.

Optionally, the flip LED chip further includes a passivation layer, the passivation layer covers a side surface of the epitaxial layer and covers a region of the electrode mounting surface of the epitaxial layer except the electrode mounting region, and the electrode mounting surface is a surface of a side of the epitaxial layer where the electrode is located.

Be provided with the passivation layer among the above-mentioned flip LED chip, the side and the electrode that the epitaxial layer had been wrapped to the passivation layer set up the subregion on the face, and the passivation layer can completely cut off the erosion of outside water oxygen to the epitaxial layer, promotes the reliability of epitaxial layer, and simultaneously, the passivation layer can also carry out electrical isolation, reinforcing flip LED chip's quality to epitaxial layer and outside.

Optionally, the passivation layer comprises a silicon oxide layer.

Optionally, the passivation layer further includes an aluminum oxide layer, and the aluminum oxide layer is coated outside the silicon oxide layer.

Besides the silicon oxide layer, the passivation layer of the flip LED chip also comprises an aluminum oxide layer covering the silicon oxide layer, double passivation is achieved by the aluminum oxide layer and the silicon oxide layer, and passivation effect is improved.

Optionally, the outer surface of the portion of the passivation layer located on the side surface of the epitaxial layer has a plurality of rugged roughened structures.

Among the above-mentioned flip LED chip, the surface that is located the passivation layer of epitaxial layer side is provided with a plurality of unsmooth alligatoring structures, utilizes alligatoring structure can reduce the probability that the total reflection takes place for light in the epitaxial layer, promotes the outer quantum efficiency of epitaxial layer and flip LED chip's luminous efficacy.

Optionally, the flip LED chip further includes a substrate layer disposed on a side of the epitaxial layer away from the ohmic contact layer.

Optionally, the interface of the substrate layer and the epitaxial layer has a relief pattern.

Concave-convex patterns are arranged on the interface of the substrate of the flip LED chip and the epitaxial layer, so that the dislocation density in the epitaxial layer can be reduced, the crystal quality of the epitaxial layer is improved, meanwhile, the concave-convex patterns can also reduce the total reflection probability of light in the epitaxial layer, and further the electrical characteristics and the optical characteristics of the flip LED chip are improved.

Based on the same inventive concept, the present application also provides a display panel, including:

the LED light source comprises a driving backboard with a driving circuit and a plurality of light emitting chips which are arranged on the driving backboard and electrically connected with the driving circuit, wherein at least part of the plurality of light emitting chips is the flip LED chip of any one of the above.

The flip LED chip contained in the display panel is provided with the ohmic contact layer between the P electrode and the P type semiconductor layer, and the ohmic contact layer can realize ohmic contact between the P electrode and the P type semiconductor layer, so that the efficiency of converting electric energy into light energy by the flip LED chip is improved. Meanwhile, the ohmic contact layer comprises two transparent conductive layers and a metal reflecting layer sandwiched between the transparent conductive layers, so that the transparent conductive layers can realize transverse current diffusion, and the light emitting uniformity of the epitaxial layer is improved; the metal reflecting layer that presss from both sides between two-layer transparent conducting layer not only the resistivity is low, can promote ohmic contact effect, and because it has the reflex action to the light that the epitaxial layer sent moreover, can prevent that the light of epitaxial layer from setting up face one side and jeting out, reduced the loss that light jetted out from one side that the face place was set up to the electrode and caused, promoted flip-chip LED chip's light-emitting efficiency, strengthened display panel's display effect.

Drawings

FIG. 1 is a schematic diagram of a flip-chip Micro-LED chip provided in a related example;

fig. 2 is a schematic structural diagram of a first flip-chip LED chip according to an alternative embodiment of the present invention;

FIG. 3 is a schematic diagram of a structure of the ohmic contact layer of FIG. 2;

fig. 4 is a schematic structural diagram of a second flip-chip LED chip provided in an alternative embodiment of the present invention;

fig. 5 is a schematic structural diagram of a third flip LED chip provided in an alternative embodiment of the present invention;

fig. 6 is a schematic structural diagram of a fourth flip LED chip according to an alternative embodiment of the present invention;

fig. 7 is a schematic structural diagram of a fifth flip-chip LED chip according to an alternative embodiment of the present invention;

fig. 8 is a schematic structural diagram of a sixth flip-chip LED chip according to an alternative embodiment of the present invention;

fig. 9 is a schematic structural diagram of a display panel according to an alternative embodiment of the present invention;

fig. 10 is a schematic view of a process for manufacturing a flip-chip LED chip according to another alternative embodiment of the present invention;

fig. 11 is a schematic view illustrating a process of flip-chip LED chip according to another alternative embodiment of the present invention.

Description of reference numerals:

10-flip chip Micro-LED chip; 11-epitaxial layer; 12-an ITO layer; 13-a passivation film; 14-chip electrodes; 15-a substrate; 20-flip-chip LED chip; a 21-N type semiconductor layer; 210-N type mesa; 22-an active layer; a 23-P type semiconductor layer; 230-P type mesa; a 24-N electrode; a 25-P electrode; 26-ohmic contact layer; 261-a transparent conductive layer; 262-a metal reflective layer; 27-a passivation layer; 271-SiO ₂ A (silicon oxide) layer 271; 272-Al ₂ O ₃ (alumina) layer 272; 28-a substrate layer; 280-a relief pattern; 40-flip-chip LED chips; 50-flip-chip LED chip; 60-flip-chip LED chips; 70-flip-chip LED chip; 80-flip LED chip; 9-a display panel; 91-driving the back plate; 92-a light emitting chip; 110-flip LED chip; 111-sapphire substrate; 112-epitaxial layer; 1121-N type GaN layer; 1122-active layer; 1123-P-type GaN layer; 113-ohmic contact layer; 1131 — first ITO layer; 1132 — a metal reflective layer; 1133 — a second ITO layer; 114-SiO ₂ A passivation layer; 115-P electrode; 116-N electrode.

Detailed Description

To facilitate an understanding of the present application, the present application will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present application are given in the accompanying drawings. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

The Micro-LED display technology is a display technology which takes self-luminous micrometer-scale LEDs as light-emitting pixel units and assembles the light-emitting pixel units on a driving backboard to form a high-density LED array. Due to the characteristics of small size, high integration level, self-luminescence and the like of the Micro-LED chip, compared with an LCD (Liquid Crystal Display) and an OLED (organic light emitting diode), the Micro-LED chip has the advantages of brightness, resolution, contrast, energy consumption, service life, response speed, thermal stability and the like in the aspect of Display. The Micro-LED comprises a chip with a positive structure, a chip with a reverse structure, a chip with a vertical structure and other structures according to the structural classification, and the chip with the reverse structure has the advantages of high reliability, low cost, small thermal resistance, high light efficiency, easiness in small size, high power and the like. Please refer to fig. 1 for a schematic structural diagram of a flip-chip Micro-LED chip:

the flip-chip Micro-LED chip 10 comprises an epitaxial layer 11, an ITO layer 12, a passivation film 13, a chip electrode 14 and a substrate 15. Wherein the ITO layer 12 is an ohmic contact layer of the flip-chip Micro-LED chip 10, and the driving current is introduced into the core particles from the chip electrode 14 and is diffused and distributed to the surface of the core particles through the ITO layer 12. The main light emitting surface of the flip Micro-LED chip 10 is the surface opposite to the surface where the chip electrodes 14 are located, in which case light absorption by the chip electrodes 14 may result in light emitting loss of the flip Micro-LED chip 10. At the same time, such as SiO ₂ (silicon oxide) and Al ₂ O ₃ The passivation film 13 such as (aluminum oxide) is a high-transmittance material, and light emitted from the epitaxial layer 11 passes through the passivation film 13 and then overflows from the side where the chip electrode 14 is located, so that a large amount of light loss is caused, and the problem of low light extraction efficiency of the flip-chip Micro-LED chip 10 is caused.

Based on this, the present application intends to provide a solution to the above technical problem, the details of which will be explained in the following embodiments.

An alternative embodiment of the present application:

the present embodiment first provides a flip LED chip, please refer to a schematic structural diagram of the flip LED chip 20 shown in fig. 2:

the flip LED chip 20 includes an epitaxial layer and an electrode, wherein the epitaxial layer includes an N-type semiconductor layer 21, an active layer 22 and a P-type semiconductor layer 23 sequentially disposed, the N-type semiconductor layer 21 is configured to be electrically connected to the N-electrode 24, the P-type semiconductor layer 23 is configured to be electrically connected to the P-electrode 25, the N-type semiconductor layer 21 provides electrons into the active layer 22 under excitation of current, the P-type semiconductor layer 23 provides holes into the active layer 22 under excitation of current, the electrons and the holes are recombined in the active layer 22, and photons are radiated at the same time, so that light emission from the epitaxial layer is realized. It is understood that the layer structure included in the epitaxial layer is not limited to the three layers, for example, in some other examples of the present embodiment, the epitaxial layer may further include a buffer layer disposed on a side of the N-type semiconductor layer 21 away from the active layer 22, where the buffer layer is configured to reduce a lattice difference between the N-type semiconductor layer 21 and the growth substrate, reduce stress, and improve the crystal quality of the epitaxial layer. In other examples, the epitaxial layer may include an electron blocking layer disposed between the active layer 22 and the P-type semiconductor layer 23, which is used to prevent electrons from overflowing from the active layer 22 to the P-type semiconductor layer 23, so that the recombination probability of electrons and holes in the active layer 22 is improved, and the internal quantum efficiency of the epitaxial layer is increased. In some examples, the epitaxial layer may further include an intrinsic layer, a bragg reflector layer, and the like.

In the present embodiment, the N-electrode 24 is disposed on a side of the N-type semiconductor layer 21 facing the active layer 22, and the P-electrode 25 is disposed on a side of the P-type semiconductor layer 23 away from the active layer 22. In the present embodiment, the epitaxial layer is etched to form an N-type mesa 210 and a P-type mesa 230, and the N-electrode 24 and the P-electrode 25 are respectively disposed on the N-type mesa 210 and the P-type mesa 230. The N electrode 24 and the P electrode 25 are oriented in the same direction, and both are disposed on the same side of the epitaxial layer, and a surface on which the electrodes are disposed on the epitaxial layer is referred to as an "electrode mounting surface", and since the flip LED chip 20 is in a flip structure, a main light emitting surface of the epitaxial layer is a surface opposite to the electrode mounting surface.

The flip LED chip 20 provided in the present embodiment further includes an ohmic contact layer 26, wherein the ohmic contact layer 26 is disposed on the P-type mesa 230, interposed between the P-electrode 25 and the P-type semiconductor layer 23, and configured to realize ohmic contact between the P-electrode 25 and the P-type semiconductor layer 23. The ohmic contact layer 26 includes two transparent conductive layers 261 and a metal reflective layer 262 sandwiched between the two transparent conductive layers 261. referring to the schematic structural diagram of the ohmic contact layer 26 shown in fig. 3, as can be seen from fig. 3, the metal reflective layer 262 and the two transparent conductive layers 261 form a "sandwich" structure, and the transparent conductive layer 261 sandwiches the metal reflective layer 262. For convenience of description, one of the two transparent conductive layers 261 closer to the epitaxial layer is referred to as a "first transparent conductive layer", and the other is referred to as a "second transparent conductive layer".

The transparent conductive layer 261 may be an oxide, nitride, fluoride film layer having transparent conductivity, for example, In ₂ O ₃ (indium oxide) layer, SnO ₂ The (TiN dioxide) layer, ZnO (zinc oxide) layer, CdO (cadmium oxide) layer, TiN (titanium nitride) layer, IZO (indium zinc oxide) layer, GZO (zinc gallium oxide) layer, AZO (aluminum-doped zinc oxide) layer, and SnO (TiN oxide) layer may be used in addition to these layers ₂ F (fluorine-doped tin dioxide) layer, TiO ₂ Ta (tantalum doped titanium dioxide) layer. Alternatively, the transparent conductive layer 261 may be a mixed oxide layer, for example, In ₂ O ₃ -ZnO (indium oxide-zinc oxide) layer, CdIn ₂ O ₄ (cadmium indium oxide) layer, CdSnO ₄ (cadmium tin oxide) layer, Zn ₂ SnO ₄ At least one of (zinc tin oxide) layers.

In some examples of the present embodiment, the first transparent conductive layer and the second transparent conductive layer may be made of the same material or different materials, for example, in one example, both of the first transparent conductive layer and the second transparent conductive layer are ITO layers. In some other examples, the first transparent conductive layer may be an ITO layer, and the second transparent conductive layer may be an IZO layer.

The metal reflective layer 262 may include at least one of an Au layer, an Ag layer, an Al layer, and a Ti layer, in some examples, the metal reflective layer 262 is a single metal layer structure, and in other examples, the metal reflective layer 262 may be a composite layer structure formed by stacking two or more layers of an Au layer, an Ag layer, an Al layer, and a Ti layer. It can be understood that these metal layer structures not only have good reflection performance, but also have low resistivity, so as to reduce the resistance between the P-electrode 25 and the P-type semiconductor layer 23 and improve the ohmic contact performance therebetween.

It should be understood that the metal reflective layer 262 is disposed on the P-type mesa 230, which can prevent the light of the epitaxial layer from being emitted from the P-type mesa 230, which greatly reduces the proportion of the light emitted from one side of the electrode mounting surface, and improves the light emitting efficiency of the main light emitting surface and the side surface of the epitaxial layer, and according to the experiment, after the ohmic contact layer 26 of the composite layer structure is disposed, the light emitting efficiency of the top surface and the side surface of the flip-chip LED chip is increased by at least 10%.

In some examples of the present embodiment, the flip LED chip further includes a passivation layer, please refer to a schematic structural diagram of another flip LED chip 40 shown in fig. 4: the flip-chip LED chip 40 also includes an N-type semiconductor layer 21, an active layer 22, a P-type semiconductor layer 23, and an ohmic contact layer 26, which are sequentially stacked, wherein the N-type semiconductor layer 21, the active layer 22, and the P-type semiconductor layer 23 belong to an epitaxial layer, an N-type mesa 210 and a P-type mesa 230 are formed on the epitaxial layer, the ohmic contact layer 26 is disposed on the P-type mesa 230, and a P-electrode 25 is also disposed on the P-type mesa 230 and electrically connected to the P-type semiconductor layer 23 through the ohmic contact layer 26. The N electrode 24 is provided on the N-type mesa 210 and electrically connected to the N-type semiconductor layer 21. In addition to the epitaxial layer and the ohmic contact layer 26, a passivation layer 27 is provided, and the passivation layer 27 covers the side surfaces of the epitaxial layer and the electrode mounting surface and the ohmic contact layer 26 is also covered with the passivation layer 27. However, the N-electrode 24 and the P-electrode 25 are exposed from the passivation layer 27, i.e., although the passivation layer 27 covers the electrode mounting surface, the passivation layer does not cover the electrode mounting region on the electrode mounting surface.

The passivation layer 27 has good insulation, which can electrically isolate the epitaxial layer and the ohmic contact layer 26 from the outside, and at the same time, because the passivation layer 27 also has waterproof property, it can block external moisture to maintain the reliability of the epitaxial layer.

In some examples of the present embodiment, the passivation layer 27 includes SiO ₂ The layer may be provided by any of evaporation, sputtering, ALD (atomic layer deposition), and the like. In some examples of the present embodiment, the passivation layer 27 may also be Al ₂ O ₃ Layer, AlN layer, AlON layer, AlF ₃ Any one of the (aluminum trifluoride) layers. In some examples of the present embodiment, the passivation layer 27 may have a single-layer structure, and in other examples, the passivation layer 27 may have a multi-layer structure, for example, which may include SiO simultaneously ₂ Layer and Al ₂ O ₃ Layer, as shown in FIG. 5, due to Al ₂ O ₃ The water-proof property of the layer is superior to that of SiO ₂ Water-proof property of the layer, so in the flip LED chip 50 shown in fig. 5, SiO ₂ Layer 271 of Al ₂ O ₃ Layer 272 is closer to the epitaxial layer, i.e., Al ₂ O ₃ Layer 272 is the outer layer and SiO ₂ Layer 271 being an inner layer, made of SiO ₂ Layer 271 of Al ₂ O ₃ The cooperation of layer 272 may enable dual protection of the epitaxial layers, facilitating improved electrical performance and longevity of flip-chip LED chip 50. Of course, it will be understood by those skilled in the art that in other examples, the passivation layer 27 of the composite layer structure may be formed of a layer of other material, or may include Al in combination with the passivation layer ₂ O ₃ Layer and SiO ₂ When layer is formed, SiO ₂ The layer is arranged on the outer layer, and Al is added ₂ O ₃ The layer is disposed on the inner layer.

In some examples of the present embodiment, in order to improve the light extraction efficiency of the flip-chip LED chip, a plurality of concave-convex roughened structures may be disposed on the outer surface of the passivation layer 27, please refer to fig. 6, in the flip-chip LED chip 60, a plurality of concave-convex roughened structures 270 are disposed on the outer surface of the passivation layer 27 covering the side surface of the epitaxial layer, and the roughened structures 270 may be formed by roughening the surface of the passivation layer 27, for example, by performing dry etching or wet etching on the surface of the passivation layer 27. It is understood that in the longitudinal section of the flip-chip LED chip 60, the rough structure 270 may have a saw-tooth shape as shown in fig. 6, a square wave shape, or a wave shape formed by a plurality of curved lines. The coarsening structure 270 changes the shape of the critical surface between the passivation layer 27 and the air, so that the light emitted from the epitaxial layer can be emitted to the critical surface at different incident angles, the probability of total reflection of the light is reduced, and the light extraction efficiency of the flip-chip LED chip 60 is further improved. In the present embodiment, since it is necessary to reduce light emitted from the electrode mounting surface side as much as possible, it is not necessary to provide roughened structures 270 on the outer surfaces of the corresponding regions in the regions where the passivation layer 27 covers the electrode mounting surface.

In some examples of the embodiment, the flip-chip LED chip further includes a substrate layer 28, as shown in fig. 7, in the flip-chip LED chip 70, the substrate layer 28 is located on a side of the N-type semiconductor layer 21 away from the active layer 22, and in some examples, it may be a growth substrate of an epitaxial layer, for example, when the N-type semiconductor layer 21 is an N-type GaN (gallium nitride) layer, the substrate layer 28 may be any one of a sapphire substrate, a silicon substrate, and a GaN substrate. Alternatively, the substrate layer 28 and the N-type semiconductor layer 21 may not be in direct contact, and a layer structure such as a buffer layer may be further provided between the substrate layer 28 and the N-type semiconductor layer 21. In some examples of the present embodiment, a surface of the substrate layer 28 facing the epitaxial layer is flat, as shown in fig. 7, and in still other examples, a surface of the substrate layer 28 facing the epitaxial layer is subjected to a patterning process, and a concave-convex pattern 280 is formed on the surface, as shown in the schematic structural diagram of the flip-chip LED chip 80 in fig. 8, and these concave-convex patterns 280 can reduce dislocations in the epitaxial layer during the growth of the epitaxial layer, and improve the crystal quality of the epitaxial layer. It is to be understood that the substrate layer 28 may not be a growth substrate for the epitaxial layer in other examples, for example, the epitaxial layer may be transferred to the substrate layer 28 after growth on the growth substrate is completed.

In the present embodiment, the flip LED chip may not be limited to any one of Mini-LED, Micro-LED or OLED. In some examples, the light emitted by the flip LED chip may be at least one of three primary colors.

As shown in fig. 9, the display panel 9 includes a driving backplane 91 and a plurality of light emitting chips 92, a driving circuit is disposed on the driving backplane 91, and chip electrodes of the plurality of light emitting chips 92 are electrically connected to the driving circuit, and can emit light under the driving of the driving circuit. In the present embodiment, at least a portion of the light emitting chips 92 may be the flip LED chips provided in any of the foregoing examples.

The flip-chip LED chip and display panel that this embodiment provided, because set up the metal reflection stratum in the ohmic contact layer of epitaxial layer in the flip-chip LED chip, utilize the metal reflection stratum to the reflective power of light, reduced the light leak of electrode setting face one side, promoted the light-emitting efficiency of flip-chip LED chip top surface and side, strengthened display panel's display effect.

Another alternative embodiment of the present application:

in this embodiment, the structure of the flip LED chip will be further described in conjunction with the process of manufacturing the flip LED chip, please refer to fig. 10 and 11, where fig. 10 shows a schematic diagram of a process of manufacturing the flip LED chip 110, and fig. 11 shows a schematic diagram of a process of manufacturing the flip LED chip 110:

s1002: an epitaxial layer with a growth substrate is provided.

Referring to fig. 11 (a), an epitaxial layer 112 is grown on a sapphire substrate 111, and the epitaxial layer 112 sequentially includes an N-type GaN layer 1121, an active layer 1122, and a P-type GaN layer 1123 from bottom to top. Other layer structures that the epitaxial layer 112 may comprise are not shown in fig. 11.

S1004: and forming an ohmic contact layer in a partial region of one surface of the epitaxial layer far away from the growth substrate.

Referring to (b) of fig. 11, an ohmic contact layer 113 may be formed on a surface of the epitaxial layer 112 away from the growth substrate 111, and the ohmic contact layer 113 covers only a partial region of the surface of the epitaxial layer 112 away from the growth substrate 111. In this embodiment, the ohmic contact layer 113 includes a first ITO layer 1131, a metal reflective layer 1132, and a second ITO layer 1133 in sequence from bottom to top. It is understood that each layer structure of the ohmic contact layer 113 may be formed by any one of evaporation, sputtering, PVD (Physical Vapor Deposition), CVD (Chemical Vapor Deposition), ALD, and the like. In some examples, when the ohmic contact layer 113 is formed, the ohmic contact layer 113 may cover the entire electrode installation surface of the epitaxial layer 112, and then the excess portion may be removed by etching or the like; or a mask is formed in a region where the electrode mounting surface of the epitaxial layer 112 is not required to be covered by the ohmic contact layer 113, then the ohmic contact layer 113 is formed under the shielding of the mask, and finally the mask and the ohmic contact layer 113 covered on the mask are removed.

In this embodiment, the metal reflective layer 1132 may be a single metal layer formed by a single metal material, and in other examples, the metal reflective layer 1132 may also be formed by two or more metal layers with different material materials.

S1006: and carrying out mesa etching and channel etching on the epitaxial layer.

After forming the ohmic contact layer 113, the epitaxial layer 112 may be etched, and the etching of the epitaxial layer 112 includes two aspects: on one hand, the epitaxial layer 112 not covered by the ohmic contact layer 113 is etched from the electrode mounting surface side until the N-type GaN layer 1121 is exposed, thereby forming an N-type mesa and a P-type mesa on the epitaxial layer 112, as shown in fig. 11 (c), in which the ohmic contact layer 113 is located on the P-type mesa. On the other hand, the epitaxial layer 112 not covered with the ohmic contact layer 113 is etched from the electrode mounting surface side until the sapphire substrate 111 is exposed, as shown in fig. 11 (d).

S1008: and forming a passivation layer for coating the epitaxial layer and the ohmic contact layer.

Subsequently, a passivation layer, which is SiO, as shown in fig. 11 (e), may be formed on the wafer source, which is an intermediate product as shown in fig. 11 (d) ₂ Passivation layer 114, SiO ₂ The passivation layer 114 is located on the side of the sapphire substrate 111 where the epitaxial layer 112 is located, and forms a full package with the sapphire substrate 111 for the epitaxial layer 112 and the ohmic contact layer 113. SiO 2 ₂ The passivation layer 114 may be formed by any one of evaporation, sputtering, PVD, CVD, ALD, and the like.

S1010: and etching the passivation layer to expose the electrode setting area.

In FIG. 11 (e), SiO ₂ The passivation layer 114 covers the side surface of the epitaxial layer 112 and the electrode mounting surface, and for facilitating the subsequent arrangement of a chip electrode electrically connected to the semiconductor layer in the epitaxial layer 112, it is necessary to apply SiO to the passivation layer 114 ₂ The passivation layer 114 is patterned, for example, by etching, so that the P electrode formation region on the ohmic contact layer 113 and the N electrode formation region on the N-type mesaSiO ₂ The passivation layer 114 is exposed thereunder as shown in (f) of fig. 11.

S1012: and forming a chip electrode in the electrode arrangement area to obtain the flip LED chip.

After the electrode arrangement regions are exposed, chip electrodes may be arranged in the two electrode arrangement regions by evaporation, deposition, or the like, as shown in (g) of fig. 11, a P electrode 115 in contact with the ohmic contact layer 113 is arranged on the P-type mesa, and an N electrode 116 electrically connected to the N-type GaN layer 1121 is arranged on the N-type mesa.

To this end, the flip-chip LED chip 110 is basically manufactured, in some examples, the sapphire substrate 111 may be peeled off after the flip-chip LED chip 110 is formed, and in other examples, the sapphire substrate 111 may be left in the flip-chip LED chip 110, so that the sapphire substrate 111 may also protect the epitaxial layer 112.

The flip-chip LED chip that this embodiment provided has set up the ohmic contact layer that the resistivity is low, the reflectance can be excellent between P type GaN layer and P electrode, utilizes this ohmic contact layer in the intraformational quantum efficiency of increase epitaxy, reduces the light-emitting of flip-chip LED chip bottom surface, increases the light-emitting of LED chip top surface and side, has promoted flip-chip LED chip's luminous luminance, and luminous luminance can promote 10%.

It is to be understood that the invention is not limited to the above-described embodiments, and that modifications and variations may be made by those skilled in the art in light of the above teachings, and all such modifications and variations are intended to be included within the scope of the invention as defined in the appended claims.

Claims

1. A flip LED chip, comprising:

the ohmic contact layer is arranged on one side, far away from the N-type semiconductor layer, of the epitaxial layer;

an N electrode electrically connected to the N-type semiconductor layer; and

a P-electrode electrically connected to the P-type semiconductor layer through the ohmic contact layer;

2. The flip LED chip of claim 1, wherein the transparent conductive layer comprises an ITO layer.

3. The flip LED chip of claim 1, wherein the metallic reflective layer comprises at least one of an Au layer, an Ag layer, an Al layer, and a Ti layer.

4. The flip LED chip of any one of claims 1 to 3, further comprising a passivation layer covering the side surface of the epitaxial layer and covering a region other than the electrode-disposing region on the electrode-disposing surface of the epitaxial layer, the electrode-disposing surface being a surface on a side of the epitaxial layer where the electrode is located.

5. The flip LED chip of claim 4, wherein the passivation layer comprises a silicon oxide layer.

6. The flip LED chip of claim 5, wherein the passivation layer further comprises an aluminum oxide layer, the aluminum oxide layer being clad outside the silicon oxide layer.

7. The flip LED chip of claim 4, wherein an outer surface of the portion of the passivation layer on the side of the epitaxial layer has a plurality of rugged roughened structures.

8. The flip LED chip of any one of claims 1-3, further comprising a substrate layer disposed on a side of the epitaxial layer away from the ohmic contact layer.

9. The flip LED chip of claim 8, wherein a side of the substrate layer facing the epitaxial layer is provided with a relief pattern.

10. A display panel, comprising:

a driving back plate having a driving circuit; and

a plurality of light emitting chips disposed on the driving backplane and electrically connected to the driving circuit, at least some of the plurality of light emitting chips being flip-chip LED chips according to any one of claims 1 to 9.