Color conversion LED chip and manufacturing method thereof

Abstract

The present invention provides a color conversion LED chip, comprising: a light-emitting epitaxial structure, on which a plurality of first through holes and steps are arranged, the first through holes and steps penetrate the P-type semiconductor layer and the light-emitting layer to a preset depth of the N-type semiconductor layer; a current expansion layer, located above the P-type semiconductor layer, on which a second through hole aligned one-to-one with the first through hole is formed; a passivation layer, arranged on the inner wall of the second through hole and the first through hole, and around the opening of the second through hole, the passivation layer and the bottom of the first through hole jointly define a cavity; a color conversion layer, located at the bottom of the cavity and in contact with the N-type semiconductor layer, the color conversion layer partially fills the cavity; a hole transport layer, filling the cavity and covering the passivation layer and the current expansion layer as a whole. The present invention can simultaneously realize the photoluminescence and electroluminescence of the color conversion layer by arranging the color conversion layer and the hole transport layer in the cavity defined in the through hole, thereby improving the color conversion efficiency and reducing the chip energy consumption.

Description

Technical Field

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

[0002] With the continuous improvement of indoor display application technology, the currently used display application products such as projection, DLP (Digital Light Processing), LCD (Liquid Crystal Display), PDP (Plasma Display Panel) can no longer fully meet the market application needs. There are still some defects in various aspects that prevent it from breaking through the development of technology. The LED (Light Emitting Diode) full-color display screen overcomes many defects of the above products and has become the first choice for indoor and outdoor large-screen displays, such as command centers, outdoor advertising screens, conference centers and other occasions.

[0003] LED chips have good energy-saving effects and high brightness, and are used in various industries of production and life. Usually, LED display screens are seamlessly spliced ​​into large-size display screens through a certain number of small-size display screen modules. Among them, one of the commonly used methods for making small-pitch display screen modules is chip on board (Chip On Board, referred to as COB). In the current process of making small-pitch LED display screens using the COB method, the chip used is a flip-chip Mini LED chip. In order to achieve full-color display, three types of Mini LED chips, red, green and blue, are required. However, in the prior art, LED chips are usually made of gallium nitride-based materials. The use of gallium nitride-based chips to make blue LEDs and green LEDs is a mature process, which is simple to make and use, but the red LED is a four-element LED, and its substrate is opaque GaAs. If you want to obtain a flip-chip red LED, you need to bond the red wafer to the sapphire substrate and then remove the GaAs substrate. The process is complicated, especially in small-pitch or micro-pitch LED display screens. The cost of flip-chip red chips accounts for a large proportion, and this process has a low production yield. In addition, compared with GaN (gallium nitride) materials, the AlInGaP epitaxial layer of red light is brittle and fragile, and device failure caused by peeling of the epitaxial film often occurs during use. The above process leads to low yield and high cost of flip-chip red light LEDs, and therefore cannot meet application needs.

[0004] Therefore, it is necessary to provide a color-convertible LED chip suitable for a small-pitch or micro-pitch LED display screen to replace the existing LED chip. Summary of the invention

[0005] In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide a color-converting LED chip and a method for manufacturing the same, so as to solve the problems of high manufacturing cost and low yield of red light chips for full-color LED display screens in the prior art, especially red light LED chips with flip-chip structures, as well as significantly reduced luminous efficiency and reliability as the chip size decreases.

[0006] To achieve the above-mentioned and other related purposes, the present invention provides a color conversion LED chip, the LED chip comprising:

[0007] A light-emitting epitaxial structure, the light-emitting epitaxial structure comprising:

[0008] N-type semiconductor layer;

[0009] A light emitting layer, located above the N-type semiconductor layer;

[0010] A P-type semiconductor layer, located above the light-emitting layer;

[0011] A plurality of first through holes are provided on the light-emitting epitaxial structure; a step is also provided on the light-emitting epitaxial structure; the first through holes and the step penetrate the P-type semiconductor layer and the light-emitting layer to a preset depth of the N-type semiconductor layer;

[0012] A current spreading layer, located above the P-type semiconductor layer, and having second through holes formed on the current spreading layer and aligned one-to-one with the first through holes;

[0013] A passivation layer is disposed on the inner walls of the second through hole and the first through hole, and around the opening of the second through hole, the passivation layer and the bottom of the first through hole jointly define a cavity, and the passivation layer as a whole is electrically insulating;

[0014] a color conversion layer, located at the bottom of the cavity and in contact with the N-type semiconductor layer, wherein the color conversion layer partially fills the cavity;

[0015] a hole transport layer, filling the cavity and entirely covering the passivation layer and the current spreading layer;

[0016] N electrode;

[0017] P electrode.

[0018] Optionally, the color conversion layer comprises a quantum dot material, and the passivation layer electrically isolates the color conversion layer from the P-type semiconductor layer and the light-emitting layer.

[0019] Optionally, the current spreading layer, the hole transport layer, the color conversion layer and the N-type semiconductor layer constitute a current transmission path.

[0020] Optionally, the N-electrode is located above the step and electrically connected to the N-type semiconductor layer, and the P-electrode is located above the P-type semiconductor layer and electrically connected to the current spreading layer.

[0021] Optionally, the P-electrode includes a P-type bottom electrode and a P-type external electrode, the P-type bottom electrode contacts the exposed surface of the current spreading layer, and the N-electrode includes an N-type bottom electrode and an N-type external electrode, the top surface of the N-type bottom electrode is flush with the top surface of the P-type bottom electrode.

[0022] Optionally, the LED chip also includes one or more of an insulating layer or a distributed Bragg reflection layer or an anti-reflection layer or a light-absorbing layer or an ink layer, and the insulating layer or the distributed Bragg reflection layer or the anti-reflection layer or the light-absorbing layer or the ink layer covers the step and the front side of the light-emitting epitaxial structure, and covers the side of the light-emitting epitaxial structure through the peripheral step, wherein the insulating layer is used to reduce leakage current on the chip surface, the distributed Bragg reflection layer is used to enhance light reflection, the anti-reflection layer is used to reduce light reflection at the interface between media, and the light-absorbing layer or the ink layer absorbs light.

[0023] The present invention also provides a full-color LED display screen, which includes an LED pixel array made of the color-converted LED chips described above.

[0024] The present invention provides a method for manufacturing a color-converting LED chip, the method comprising the following steps:

[0025] 1) providing a substrate, and forming an N-type semiconductor layer, a light-emitting layer, and a P-type semiconductor layer from bottom to top on the substrate to form an epitaxial stack structure;

[0026] 2) etching the epitaxial stack structure to form a peripheral step and defining a plurality of LED chips on the substrate;

[0027] 3) forming a step in each LED chip to expose a portion of the N-type semiconductor layer to separate the light-emitting epitaxial structure; and simultaneously forming a plurality of first through holes penetrating the N-type semiconductor layer;

[0028] 4) forming a current spreading layer on the light-emitting epitaxial structure, and patterning the current spreading layer to form a second through hole aligned one-to-one with the first through hole;

[0029] 5) forming a passivation layer on the inner wall and the periphery of the opening of the second through hole and the inner wall of the first through hole to form a cavity defined by the passivation layer and the bottom of the first through hole;

[0030] 6) forming a color conversion layer in the cavity;

[0031] 7) forming a hole transport layer by filling the cavity with a hole transport material and entirely covering the passivation layer and the current spreading layer;

[0032] 8) Forming a P-type bottom electrode and an N-type bottom electrode on the P-type semiconductor layer and the N-type semiconductor layer, respectively.

[0033] Optionally, in step 6), the color conversion layer includes a quantum dot material, and the quantum dot material fills the bottom of the cavity and contacts the N-type semiconductor layer.

[0034] Optionally, in step 7), the current spreading layer, the hole transport layer, the color conversion layer and the N-type semiconductor layer constitute a current transmission path.

[0035] Optionally, the manufacturing method further comprises:

[0036] 9) forming one or more of an insulating layer, a distributed Bragg reflection layer, an anti-reflection layer, a light absorbing layer, or an ink layer on the step, the front surface of the light-emitting epitaxial structure, and the side surface of the light-emitting epitaxial structure;

[0037] 10) forming a P-type external electrode and an N-type external electrode through the insulating layer or the distributed Bragg reflection layer or the anti-reflection layer or the light absorption layer or the ink layer.

[0038] As described above, the color conversion LED chip and the manufacturing method thereof of the present invention have the following beneficial effects:

[0039] The present invention utilizes a plurality of through holes arranged on a light-emitting epitaxial structure, and arranges a color conversion layer and a hole transport layer in a cavity defined in the through holes. The color conversion layer is located at the bottom of the cavity and contacts the N-type semiconductor layer, and the hole transport layer is located above the color conversion layer and fills the cavity. The photoluminescence and electroluminescence of the color conversion layer can be realized simultaneously, thereby improving the color conversion efficiency and reducing the energy consumption of the chip.

[0040] The manufacturing method provided by the present invention has high repeatability, and can effectively reduce the manufacturing cost, especially the flip-chip structure red light LED chip, and improve the production yield, so as to be applied to small-pitch or micro-pitch LED display screens. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figures 1 to 8 The structure diagram of each step of manufacturing a color conversion LED chip of the present invention is shown; wherein, Figure 2B to Figure 2C Display as Figure 2A The schematic cross-sectional view of the structure obtained in step 3) of the present invention along the a-plane and the b-plane, Figure 3B to Figure 3C Display as Figure 3AThe schematic cross-sectional view of the structure obtained in step 4) of the present invention along the a-plane and the b-plane is shown, Figure 4B to Figure 4C Display as Figure 4A The schematic cross-sectional view of the structure obtained in step 5-1) of the present invention along the a-plane and the b-plane is shown, Figure 8 It is a schematic diagram of the cross-sectional structure of the LED chip of the present invention.

[0042] Component number description

[0043] 100 Substrate

[0044] 210 Buffer layer

[0045] 220 Intrinsic semiconductor layer

[0046] 230 N-type semiconductor layer

[0047] 231 First through hole

[0048] 232 Second through hole

[0049] 234 Cavity

[0050] 240 Luminous Layer

[0051] 250 Electron blocking layer

[0052] 260 P-type semiconductor layer

[0053] 270 Current Expansion Layer

[0054] 280 Passivation layer

[0055] 291 P-type bottom electrode

[0056] 292 N-type bottom electrode

[0057] 293 P-type external electrode

[0058] 294 N-type external electrode

[0059] 300 color conversion layers

[0060] 310 Hole transport layer

[0061] 320 Insulation layer or distributed Bragg reflection layer or anti-reflection layer or light absorption layer or ink layer

[0062] 235a, 235b stairs

[0063] 225c Outer steps DETAILED DESCRIPTION

[0064] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0065] For example, when describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional view showing the device structure will not be partially enlarged according to the general scale, and the schematic view is only an example, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional space dimensions of length, width and depth should be included.

[0066] For ease of description, spatially relative terms such as "under", "below", "below", "below", "above", "on", etc. may be used herein to describe the relationship of one element or feature shown in the drawings to other elements or features. It will be understood that these spatially relative terms are intended to encompass other orientations of the device in use or operation in addition to the orientation depicted in the drawings. In addition, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present.

[0067] In the context of the present application, a structure in which a first feature is described as being "above" a second feature may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features are formed between the first and second features, such that the first and second features may not be in direct contact.

[0068] It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and therefore the illustrations only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0069] Embodiment 1

[0070] This embodiment provides a color conversion LED chip, see Figure 8 , Figure 8The cross-sectional structure diagram of the color conversion LED chip is shown, and the LED chip includes a substrate 100 and a light-emitting epitaxial structure, and the light-emitting epitaxial structure is located on the front of the substrate 100 and includes: an N-type semiconductor layer 230, a light-emitting layer 240, a P-type semiconductor layer 260, and a current spreading layer 270, wherein the light-emitting layer 240 is located above the N-type semiconductor layer 230, and the P-type semiconductor layer 260 is located above the light-emitting layer 240. The light-emitting epitaxial structure is provided with a plurality of regularly arranged first through holes 231, and is also provided with steps, and the first through holes 231 and the steps penetrate the P-type semiconductor layer 260 and the light-emitting layer 240 to a predetermined depth of the N-type semiconductor layer 230, so that the surface of the N-type semiconductor layer is exposed at the bottom of the first through holes 231 and the steps.

[0071] Specifically, the material of the substrate 100 includes one of sapphire, silicon carbide and silicon. In the present embodiment, the material of the substrate 100 is sapphire. As an example, the steps 235a and 235b penetrate the P-type semiconductor layer 260 and the light-emitting layer 240, and expose part of the surface of the N-type semiconductor layer 230, and an N-boss electrode structure (N_mesa structure) is sandwiched between the steps 235a and 235b, and the N_mesa structure is consistent with the structure of the light-emitting epitaxial structure 301. Alternatively, as an alternative, the light-emitting epitaxial structure has an electrode step that penetrates the surface of the N-type semiconductor layer, which is used to set the N electrode.

[0072] The LED chip further includes a current spreading layer 270, which is located above the P-type semiconductor layer 260, and a second through hole 232 is formed on the current spreading layer 270, which is aligned one-to-one with the first through hole 231. The current spreading layer 270 can be a transparent conductive layer, and the material of the transparent conductive layer includes but is not limited to indium tin oxide (ITO), and its thickness ranges from 10 nanometers to 400 nanometers. The current spreading layer 270 can effectively improve the uniformity of the injected current and improve the utilization efficiency of the current. The LED chip further includes a passivation layer 280, which is arranged on the inner walls of the second through hole 232 and the first through hole 231, and around the opening of the second through hole 232, so that the passivation layer 280 and the bottom of the first through hole jointly define a cavity. A color conversion layer 300 and a hole transport layer 310 are disposed in the cavity. The color conversion layer 300 is located at the bottom of the cavity and contacts the N-type semiconductor layer 230 . The color conversion layer partially fills the cavity. The hole transport layer 310 fills the cavity and entirely covers the passivation layer 280 and the current spreading layer 270 .

[0073] Specifically, the first through hole 231 is arranged to penetrate the P-type semiconductor layer 260, the light emitting layer 240 to a preset depth of the N-type semiconductor layer, and the second through hole 232 penetrates the current spreading layer 270 and is aligned one-to-one with the first through hole. In some examples, the second through hole 232 may have a diameter not less than that of the first through hole 231. In this embodiment, the diameter of the second through hole 232 may be equal to the diameter of the first through hole 231, so as to form a passivation layer with good step coverage.

[0074] like Figure 8 As shown, the passivation layer 280 is electrically insulating as a whole to electrically isolate the color conversion layer 300 from the P-type semiconductor layer 260 and the light-emitting layer 240, and the passivation layer 280 and the bottom of the first through hole jointly define the cavity. The color conversion layer 300 contacts the N-type semiconductor layer 230 at the bottom of the cavity and partially fills the cavity. The color conversion layer 300 partially fills the cavity, that is, the filling height of the color conversion layer 300 is lower than the depth of the cavity. By partially filling the color conversion layer in the cavity that penetrates the N-type semiconductor layer 230, the conductive path of the LED will not be blocked, so that it can emit blue light normally, and the closed space formed by the cavity is conducive to improving the reliability of the quantum dots. Preferably, the color conversion layer is a quantum dot material, or a mixture of quantum dots and conductive glue, such as a core-shell structure quantum dot material dispersed in a conductive glue. Since the light from the light-emitting layer can excite the quantum dots to inject energy into the quantum dots, the quantum dots are used as down-conversion materials, can effectively absorb the blue light spectrum of the GaN-based LED, and the III-V LED light-emitting device has excellent efficiency, and the color conversion of the blue light can be achieved through photoluminescence. Specifically, the color conversion layer 300 can be used to convert the blue light emitted by the light-emitting layer 240 into light of other colors. For example, when the color conversion layer 300 is a red color conversion layer, the color conversion layer 300 converts the blue light emitted by the epitaxial layer into red light. For example, when the color conversion layer 300 is a green color conversion layer, the color conversion layer 300 converts the blue light emitted by the epitaxial layer into green light.

[0075] As an example, the LED chip further includes a hole transport layer 310 located above the color conversion layer 300, the hole transport layer 310 fills the cavity and entirely covers the passivation layer 280 and the current expansion layer 270, and the current expansion layer 270, the hole transport layer 310, the color conversion layer 300 and the N-type semiconductor layer 220 form a current transmission path. By providing the hole transport layer 310, the potential barrier of hole injection is reduced, which is conducive to promoting the transmission of holes to the color conversion layer through the anode, thereby increasing the probability of positive and negative carrier balance of the device, and realizing the electroluminescence of the color conversion layer 300.

[0076] The LED chip further includes a P electrode and an N electrode, wherein the N electrode is located above the step and electrically connected to the N-type semiconductor layer 230, and the P electrode is located above the P-type semiconductor layer and electrically connected to the current spreading layer 270. The LED chip further includes one or more of an insulating layer, a distributed Bragg reflector layer, an anti-reflection layer, a light absorbing layer, or an ink layer 320, wherein the insulating layer, the distributed Bragg reflector layer, the anti-reflection layer, the light absorbing layer, or the ink layer 320 covers the step and the front of the light-emitting epitaxial structure, and the side of the light-emitting epitaxial structure, wherein the insulating layer is used to reduce the leakage current on the chip surface, the distributed Bragg reflector layer is used to increase the light reflection from the light-emitting layer, the anti-reflection layer is used to absorb the light emitted from the light-emitting layer 240 and finally emitted to the anti-reflection layer, thereby reducing the light reflection at the interface between the media, and the light absorbing layer or the ink layer plays a role in absorbing light, especially absorbing the blue light leaked from the light-emitting epitaxial structure. In some examples, the light absorbing layer or ink layer can be configured to cover the outside of the distributed Bragg reflector layer, so that the light absorbing layer or ink layer can resist the reflector layer, further preventing blue light leakage, and improving the display contrast.

[0077] For example, the distributed Bragg reflector is formed by stacking multiple layers of SiO2 / Ti3O5. In some examples, a thin layer of silicon dioxide is also provided on the lower surface of the distributed Bragg reflector to provide better insulation performance and enhance the adhesion of the distributed Bragg reflector. The emitted blue light is concentrated toward the light-emitting surface so that more blue light is converted through the color conversion layer 300, further improving the color conversion effect and effectively reducing blue light leakage. Therefore, the technical solution of this embodiment can realize the optical excitation and electrical excitation of quantum dots, while solving the problem of poor color conversion effect caused by leakage of blue light when blue light LEDs excite quantum dots.

[0078] As an example, the P-electrode includes a P-type bottom electrode 291 and a P-type external electrode 293, wherein the P-type bottom electrode 291 contacts the exposed surface of the current spreading layer, and the P-type external electrode 293 passes through an insulating layer or a distributed Bragg reflector layer or an anti-reflection layer or a light absorbing layer or an ink layer 320 to connect with the P-type bottom electrode 291; the N-electrode includes an N-type bottom electrode 292 and an N-type external electrode 294, wherein the N-type bottom electrode 292 is located above the surface of the N-type semiconductor layer 230 exposed by the step and surrounds the N_mesa structure and its top, and is electrically connected to the N-type semiconductor layer 230; the N-type external electrode 294 passes through the insulating layer or the distributed Bragg reflector layer or the anti-reflection layer or the light absorbing layer or the ink layer 320 to connect with the N-type bottom electrode 293. Preferably, the top surface of the N-type external electrode is flush with the top surface of the P-type external electrode, which can facilitate the packaging connection of the LED chip with other circuits, and can also reduce the chip fracturing and the extrusion of the insulating material layer during the packaging process.

[0079] As an example, the light-emitting epitaxial structure includes a buffer layer 210, an intrinsic semiconductor layer 220, an N-type semiconductor layer 230, a light-emitting layer 240, an electron blocking layer 250 and a P-type semiconductor layer 260. The buffer layer 210 includes one of an aluminum nitride buffer layer and a gallium nitride buffer layer, and its thickness ranges from 10 to 30 nanometers, such as 15 nanometers, 20 nanometers, etc. The intrinsic semiconductor layer 220 includes an undoped gallium nitride layer, the N-type semiconductor layer 230 includes an N-type gallium nitride layer, the P-type semiconductor layer 260 includes a P-type gallium nitride layer, and the light-emitting layer 240 includes a quantum well superlattice layer. By providing the electron blocking layer 250, electrons can be confined to the quantum well region, reducing electron leakage, increasing recombination efficiency, and thus improving device performance.

[0080] The LED chip further includes a peripheral step 225c, which is annular and penetrates the P-type semiconductor layer 260, the light-emitting layer 240 and the N-type semiconductor layer 230, and exposes a portion of the surface of the substrate 100. By providing the peripheral step 225c, potential leakage channels can be effectively reduced and the antistatic performance of the chip can be improved.

[0081] Optionally, the passivation layer 280 is also disposed on the exposed surfaces of the steps 235a, 235b and the side of the light-emitting epitaxial structure, and is covered on the side of the light-emitting epitaxial structure by the peripheral step 225c. The passivation layer disposed around the chip and the inner wall of the cavity can be used to repair chip damage caused by the formation process of the steps and through holes.

[0082] By implementing the technical solution of this embodiment, the light-emitting epitaxial structure emits blue light, which causes the color conversion layer arranged around it to be excited to perform color conversion, thereby realizing LEDs of other colors, effectively reducing the cost of red light LED chips, and synchronously realizing the electroluminescence of quantum dots, providing a color conversion solution that can improve luminous efficiency and production yield.

[0083] This embodiment also provides a full-color LED display screen, which includes an LED pixel array made of the color-converted LED chips as described above.

[0084] Embodiment 2

[0085] like Figures 1 to 8 As shown, this embodiment provides a method for manufacturing a color conversion LED chip, the manufacturing method comprising the steps of:

[0086] like Figure 1 As shown, firstly, step 1) is performed to provide a substrate 100 , and an epitaxial stack structure is formed on the substrate 100 , wherein the epitaxial stack structure includes a buffer layer 210 , an intrinsic semiconductor layer 220 , an N-type semiconductor layer 230 , a light emitting layer 240 , an electron blocking layer 250 and a P-type semiconductor layer 260 .

[0087] Specifically, a sapphire substrate or a silicon carbide substrate can be sent to a magnetron sputtering machine to deposit an aluminum nitride buffer layer on the sapphire substrate or the silicon carbide substrate, and the thickness thereof can be 10-20 nanometers, such as 15 nanometers, etc. A sapphire substrate or a silicon carbide substrate can also be sent to a metal oxide chemical vapor deposition (MOCVD) reaction chamber to deposit a low-temperature gallium nitride buffer layer on the sapphire substrate or the silicon carbide substrate, and the thickness thereof can be 10-30 nanometers, such as 20 nanometers, etc.

[0088] Then, the substrate 100 formed with the buffer layer 210 may be sent into a MOCVD reaction chamber, and the intrinsic semiconductor layer 220 , the N-type semiconductor layer 230 , the light emitting layer 240 , the electron blocking layer 250 and the P-type semiconductor layer 260 may be continuously grown thereon to form a wafer.

[0089] like Figure 2A to Figure 2C As shown, step 2) is then performed to etch the epitaxial stack structure to form a peripheral step 225 c and define a plurality of LED chips on the substrate 100 .

[0090] In this embodiment, if Figure 2B to Figure 2CAs shown, in step 2), an inductively coupled plasma etching (ICP) process is used to etch a peripheral step 225c in the light-emitting epitaxial structure. The peripheral step 225c is ring-shaped and passes through the P-type semiconductor layer 260, the light-emitting layer 240 and the N-type semiconductor layer 230, and exposes a portion of the surface of the substrate 100.

[0091] Continue to see Figure 2B to Figure 2C , proceed to step 3), forming a step in each LED chip to expose a portion of the N-type semiconductor layer to separate the light-emitting epitaxial structure; and simultaneously forming a plurality of first through holes 231 penetrating into the N-type semiconductor layer 230.

[0092] Specifically, the steps 235a and 235b can be etched by inductively coupled plasma etching (ICP) process to expose a portion of the N-type semiconductor layer 260, and the N_mesa structure is sandwiched between the steps 235a and 235b, and the N_mesa structure is consistent with the light-emitting epitaxial structure.

[0093] Specifically, step 3) also includes: using a photolithography process to define a graphic area corresponding to the first through hole on the light-emitting epitaxial structure; while etching the steps 235a and 235b through an etching process, etching the light-emitting epitaxial structure to form a plurality of regularly arranged first through holes 231, wherein the first through holes 231 penetrate the P-type semiconductor layer 260, the light-emitting layer 240 and reach the N-type semiconductor layer 230.

[0094] In some embodiments, step 3) may be performed after step 2); in other embodiments, step 3) may be performed before step 2).

[0095] See also Figure 3A to Figure 3C , then proceed to step 4), a current spreading layer 270 may be formed on the P-type semiconductor layer 260, and the current spreading layer 270 may be patterned to form a second through hole 232 that is aligned one-to-one with the first through hole 231.

[0096] For example, a current spreading layer 270 may be formed on the P-type semiconductor layer 260 by sputtering, and the current spreading layer 108 may be a transparent conductive layer, the material of the transparent conductive layer includes but is not limited to indium tin oxide (ITO), and the thickness ranges from 10 nanometers to 400 nanometers. The current spreading layer 270 may effectively improve the uniformity of the injected current and improve the utilization efficiency of the current.

[0097] See also Figure 4A to Figure 4CAs shown, step 5) is then performed to form a passivation layer 280 on the inner wall and the periphery of the opening of the second through hole 232 and the inner wall of the first through hole 231 to form a cavity 234 defined by the passivation layer 280 and the bottom of the first through hole.

[0098] Specifically, the passivation layer 280 is plated on the opening periphery and inner wall of the second through hole and the inner wall of the first through hole by using an atomic layer deposition (ALD) process, so that no conductive path or leakage path is formed on the inner walls of the second through hole and the first through hole.

[0099] In this embodiment, in step 5), when the passivation layer 280 is formed on the inner wall and the periphery of the opening of the plurality of second through holes 232 and the inner wall of the first through hole 231, the passivation layer is simultaneously formed on the exposed surface of the N-platform electrode structure and the side surface of the light-emitting epitaxial structure, and the passivation layer covers the side surface of the light-emitting epitaxial structure through the peripheral step 225c. Figure 4B to Figure 4C As shown, by simultaneously coating the passivation layer around the chip, chip damage caused by the etching process of forming the step and the first through hole can be repaired.

[0100] See also Figure 5 , proceed to step 6), forming a color conversion layer 300 in the cavity 234, wherein the color conversion layer 300 partially fills the cavity 234, that is, the filling height of the color conversion layer 300 is lower than the depth of the cavity 234; preferably, the color conversion layer is a quantum dot material, or a mixture of quantum dots and conductive glue, for example, the quantum dot film can be formed by spin coating the core-shell structure quantum dot material uniformly dispersed in the conductive glue in the first through hole 232, and then curing. The light from the light-emitting layer can excite the quantum dots to inject energy into the quantum dots. The quantum dots are used as down-conversion materials and can effectively absorb the blue light spectrum of GaN. Since the III-V LED light-emitting device has excellent efficiency, the color conversion of blue light can be achieved through photoluminescence.

[0101] like Figure 6 As shown, proceed to step 7), a hole transport layer 310 is formed by filling the cavity 234 with a hole transport material and entirely covering the passivation layer 280 and the current spreading layer 270 .

[0102] Specifically, the current spreading layer 270, the hole transport layer 310, the color conversion layer 300 and the N-type semiconductor layer 230 form a current transmission path. As an example, the hole transport layer can be made of a conductive polymer such as poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) by vacuum thermal evaporation coating to reduce the potential barrier of hole injection, which is conducive to promoting the transmission of holes to the color conversion layer through the anode, thereby increasing the probability of positive and negative carrier balance of the device, and realizing the electroluminescence of the color conversion layer 300.

[0103] like Figure 7 As shown, step 8) is performed to form a P-type bottom electrode 291 and an N-type bottom electrode 292 above the P-type semiconductor layer 260 and the N-type semiconductor layer 240, respectively, the P-type bottom electrode 291 is in contact with the current spreading layer 270, and the N-type bottom electrode 292 is formed on the N-type boss electrode structure.

[0104] Specifically, the N-type bottom electrode 292 can be formed on the N-type semiconductor layer 230 exposed by the steps 235a and 235b by thermal evaporation or electron beam evaporation, and its composition can be a Cr / Al / Pt / Cr / Pt / Cr / Pt / Au / Ti stack; then the P-type bottom electrode 291 can be formed on the current spreading layer 270 by thermal evaporation or electron beam evaporation, and its composition can be a Cr / Al / Ti / Pt / Au / Ti stack. Finally, by adjusting the thickness, the top surfaces of the N-type bottom electrode 292 and the P-type bottom electrode 291 are flush, so that the subsequent etching process of forming the electrode contact holes corresponding to the P-type external electrode and the N-type external electrode can stop at the same plane at the same time, which greatly reduces the difficulty of etching the electrode contact holes and saves process costs.

[0105] like Figure 8 As shown, the color conversion LED chip manufacturing method also includes: 9) forming one or more of an insulating layer or a distributed Bragg reflection layer or an anti-reflection layer or a light absorbing layer or an ink layer 320 on the step and the front side of the light-emitting epitaxial structure, and the side of the light-emitting epitaxial structure; 10) forming a P-type external electrode 293 and an N-type external electrode 294 through the insulating layer or the distributed Bragg reflection layer or the anti-reflection layer or the light absorbing layer or the ink layer 320.

[0106] Specifically, a distributed Bragg reflector 320 may be formed on the steps 235a, 235b and the front and side surfaces of the light-emitting epitaxial structure by using a process such as electron beam evaporation, and the distributed Bragg reflector is formed by stacking multiple layers of SiO2 / Ti3O5. Alternatively, step 9) may include: forming a light absorbing layer or an ink layer on the steps and the front surface of the light-emitting epitaxial structure, and the side surfaces of the light-emitting epitaxial structure, wherein the light absorbing layer or the ink layer absorbs the blue light leaked from the light-emitting epitaxial structure. In some examples, the light absorbing layer or the ink layer may be arranged to cover the outside of the distributed Bragg reflector, so that the light absorbing layer or the ink layer can resist the reflector layer, further preventing the leakage of blue light, and improving the contrast of the display.

[0107] In this embodiment, the insulating layer or distributed Bragg reflector layer or anti-reflection layer or light absorbing layer or ink layer 320 covers the side surface of the light-emitting epitaxial structure via the peripheral step 225c.

[0108] Specifically, an inductively coupled plasma etching (ICP) process can be used to form the P-type external electrode 293 and the N-type external electrode 294 through the insulating layer or the distributed Bragg reflector layer or the anti-reflection layer or the light absorbing layer or the ink layer 320. Since the top surface of the P-type bottom electrode and the top surface of the N-type bottom electrode are flush, the inductively coupled plasma etching (ICP) process can stop at the top surfaces of the P-type bottom electrode and the N-type bottom electrode at the same time, which greatly reduces the process difficulty.

[0109] As an example, the P-type external electrode 293 and the N-type external electrode 294 may each include two parts, including a transition part and an outer part. The P-type external electrode 293 and the N-type external electrode 294 may be manufactured by thermal evaporation or electron beam evaporation. The material and thickness of the P-type external electrode and the N-type external electrode may be appropriately determined as needed.

[0110] In this embodiment, the top surfaces of the N-type external electrode 294 and the P-type external electrode 293 are flush with each other, which can facilitate the packaging connection between the LED chip and other circuits.

[0111] As described above, the color conversion LED chip and the manufacturing method thereof of the present invention have the following beneficial effects:

[0112] The present invention utilizes a plurality of through holes that are arranged on a light-emitting epitaxial structure and penetrate into an N-type semiconductor layer, and by arranging a color conversion layer and a hole transport layer in a cavity defined in the through holes, the color conversion layer is located at the bottom of the cavity and contacts the N-type semiconductor layer, and the hole transport layer is located above the color conversion layer and fills the cavity, so that the photoluminescence and electroluminescence of the color conversion layer can be realized simultaneously, thereby improving the color conversion efficiency and reducing the energy consumption of the chip.

[0113] The manufacturing method provided by the present invention has high repeatability, and can effectively reduce the manufacturing cost, especially the flip-chip structure red light LED chip, and improve the production yield, so as to be applied to small-pitch or micro-pitch LED display screens.

[0114] Therefore, the present invention effectively overcomes various shortcomings in the prior art and has high industrial utilization value.

[0115] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A color conversion LED chip, characterized in that: The LED chip comprises: A light-emitting epitaxial structure, the light-emitting epitaxial structure comprising: N-type semiconductor layer; A light emitting layer, located above the N-type semiconductor layer; A P-type semiconductor layer, located above the light-emitting layer; A plurality of first through holes are provided on the light-emitting epitaxial structure; a step is also provided on the light-emitting epitaxial structure; the first through holes and the step penetrate the P-type semiconductor layer and the light-emitting layer to a preset depth of the N-type semiconductor layer; A current spreading layer, located above the P-type semiconductor layer, and having second through holes formed on the current spreading layer and aligned one-to-one with the first through holes; A passivation layer is disposed on the inner walls of the second through hole and the first through hole, and around the opening of the second through hole, the passivation layer and the bottom of the first through hole jointly define a cavity, and the passivation layer as a whole is electrically insulating; a color conversion layer, located at the bottom of the cavity and in contact with the N-type semiconductor layer, the color conversion layer partially filling the cavity, the color conversion layer comprising a quantum dot material, the quantum dot material filling the bottom of the cavity and in contact with the N-type semiconductor layer; a hole transport layer filling the cavity and entirely covering the passivation layer and the current spreading layer, wherein the current spreading layer, the hole transport layer, the color conversion layer and the N-type semiconductor layer constitute a current transmission path, thereby simultaneously realizing photoluminescence and electroluminescence of the color conversion layer; N electrode; P electrode.

2. The LED chip according to claim 1, characterized in that: The passivation layer electrically isolates the color conversion layer from the P-type semiconductor layer and the light emitting layer.

3. The LED chip according to claim 1, characterized in that: The N-electrode is located above the step and is electrically connected to the N-type semiconductor layer, and the P-electrode is located above the P-type semiconductor layer and is electrically connected to the current spreading layer.

4. The LED chip according to claim 1, characterized in that: The P-electrode includes a P-type bottom electrode and a P-type external electrode, the P-type bottom electrode contacts the exposed surface of the current spreading layer, and the N-electrode includes an N-type bottom electrode and an N-type external electrode, the top surface of the N-type bottom electrode is flush with the top surface of the P-type bottom electrode.

5. The LED chip according to claim 1, characterized in that: The LED chip also includes one or more of an insulating layer or a distributed Bragg reflection layer or a reflection layer or a light absorbing layer or an ink layer, wherein the insulating layer or the distributed Bragg reflection layer or the anti-reflection layer or the light absorbing layer or the ink layer covers the step and the front side of the light-emitting epitaxial structure, and covers the side of the light-emitting epitaxial structure through the peripheral step, wherein the insulating layer is used to reduce leakage current on the chip surface, the distributed Bragg reflection layer is used to enhance light reflection, the anti-reflection layer is used to reduce light reflection at the interface between media, and the light absorbing layer or the ink layer plays a role in absorbing light.

6. A full-color LED display, characterized in that: The full-color LED display screen comprises: an LED pixel array made of the color-converted LED chip according to any one of claims 1 to 5.

7. A method for manufacturing a color conversion LED chip, characterized in that: The production method comprises the following steps: 1) providing a substrate, and forming an N-type semiconductor layer, a light-emitting layer, and a P-type semiconductor layer from bottom to top on the substrate to form an epitaxial stack structure; 2) etching the epitaxial stack structure to form a peripheral step and defining a plurality of LED chips on the substrate; 3) forming a step in each LED chip to expose a portion of the N-type semiconductor layer to separate the light-emitting epitaxial structure; and simultaneously forming a plurality of first through holes penetrating the N-type semiconductor layer; 4) forming a current spreading layer on the light-emitting epitaxial structure, and patterning the current spreading layer to form a second through hole aligned one-to-one with the first through hole; 5) forming a passivation layer on the inner wall and the periphery of the opening of the second through hole and the inner wall of the first through hole to form a cavity defined by the passivation layer and the bottom of the first through hole; 6) forming a color conversion layer in the cavity, wherein the color conversion layer comprises a quantum dot material, the quantum dot material fills the bottom of the cavity and contacts the N-type semiconductor layer; 7) forming a hole transport layer by filling the cavity with a hole transport material and entirely covering the passivation layer and the current spreading layer, wherein the current spreading layer, the hole transport layer, the color conversion layer and the N-type semiconductor layer constitute a current transmission path, thereby simultaneously achieving photoluminescence and electroluminescence of the color conversion layer; 8) Forming a P-type bottom electrode and an N-type bottom electrode on the P-type semiconductor layer and the N-type semiconductor layer, respectively.

8. The method according to claim 7, characterized in that: The production method also includes: 9) forming one or more of an insulating layer, a distributed Bragg reflection layer, an anti-reflection layer, a light absorbing layer, or an ink layer on the step, the front surface of the light-emitting epitaxial structure, and the side surface of the light-emitting epitaxial structure; 10) Forming a P-type external electrode and an N-type external electrode through the insulating layer or the distributed Bragg reflector layer or the anti-reflection layer or the light absorbing layer or the ink layer.

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