CN213366616U - Micro light emitting diode array - Google Patents

Abstract

The utility model provides a miniature LED array. The array includes: a support substrate; the light emitting structure of the light emitting diode is arranged on the surface of the supporting substrate; the insulating layer surrounds the light-emitting structure, a light reflecting layer is arranged between the insulating layer and the side wall of the light-emitting structure, and the light reflecting layer is obliquely arranged so as to have the function of gathering emergent light of the light-emitting diode.

Description

Micro light emitting diode array

Technical Field

The utility model relates to a semiconductor shows and the illumination field especially relates to a miniature emitting diode array.

Background

With the development and progress of science and technology, higher requirements are put forward on the next generation of lighting and display technology. Because the Micro light-emitting diode (Micro-LED) has the characteristics of micron-sized size, self-luminescence, high corresponding speed, low power consumption and the like, the technical route of realizing self-luminescence full-color display by integrating the red, green and blue Micro-LEDs on the TFT or CMOS substrate as display pixel points is known as the core technology of the next generation of novel full-color display, and the Micro light-emitting diode has wide market application prospect. However, the current Micro-LED full color display still has many challenges: 1) with the miniaturization of chip size, the influence of surface non-radiative recombination is increasing, so that the luminous efficiency of the chip is reduced with the reduction of chip size. It becomes important how to avoid or reduce the damage to the sidewalls caused by etching during the chip manufacturing process. 2) The tiny chip spacing in high-resolution display causes optical crosstalk between chips to be solved urgently. 3) The problems that a driving circuit is complex due to the fact that driving voltages of the red light Micro-LED and the blue and green light Micro-LEDs are different, cost is high due to the fact that three times of huge transfer is needed for full-color display, and the like are solved.

Disclosure of Invention

The utility model aims to solve the technical problem that a miniature light emitting diode array is provided.

In order to solve the above problem, the utility model provides a miniature light emitting diode array, include: a support substrate; the light emitting structure of the light emitting diode is arranged on the surface of the supporting substrate; the insulating layer surrounds the light-emitting structure, a light reflecting layer is arranged between the insulating layer and the side wall of the light-emitting structure, and the light reflecting layer is obliquely arranged so as to have the function of gathering emergent light of the light-emitting diode.

The technical scheme is as follows: 1) the etching step required in the conventional chip manufacturing process is avoided, so that the damage of the side wall of the chip generated in the etching process is avoided, and the non-radiative recombination center of the side wall of the chip is reduced, so that the non-radiative recombination of the side wall of the chip is avoided, and the luminous efficiency of the chip is improved. 2) The mask layer/high light reflection layer between the array chips simultaneously plays a role in preventing the light crosstalk problem caused by the light emission of the side walls of the adjacent chips, and the light reflection layer can also play a role in light condensation, so that the light emitting efficiency is further improved. 3) The single-color display can be directly bonded with substrates such as TFT, CMOS, glass and the like to realize single-color display, avoid the huge transfer required by the conventional chip and reduce the cost. 4) The blue light array chip can be combined with red and green quantum dots to realize full-color display, so that the problems of multiple times of mass transfer and complex driving circuits caused by inconsistent driving voltages of the red light Micro-LED and the blue and green light Micro-LEDs are avoided, and the cost is reduced.

Drawings

Fig. 1 is a schematic diagram illustrating the steps for fabricating the structure according to an embodiment of the present invention.

Fig. 2A to 2L are schematic views of the process according to the above embodiment.

Fig. 3A to 3C are schematic views of the process of step S12 in the step of fig. 1.

Detailed Description

The following describes in detail a specific embodiment of a micro led array according to the present invention with reference to the accompanying drawings.

Fig. 1 is a schematic view showing steps for manufacturing the structure according to an embodiment of the present invention, including: step S10, providing a first supporting substrate; step S11, manufacturing a graphical insulating layer on the surface of the first supporting substrate, wherein the hollow part of the graphical insulating layer is provided with an open-shaped side wall; step S12, growing a light reflecting layer on the side wall of the hollow part of the graphical insulating layer; step S13, growing a light-emitting structure of the light-emitting diode at the hollow part of the graphical insulating layer; step S14, providing a second supporting substrate; a step S15 of bonding the light emitting structure to the second support substrate; step S16, removing the first supporting substrate until the light emitting structure of the light emitting diode is exposed; step S17, forming a first electrode on an exposed surface of the light emitting structure of the light emitting diode; step S18, bonding the second supporting substrate already provided with the light-emitting structure with a driving circuit board, wherein the first electrode of the light-emitting structure of the light-emitting diode is aligned with the corresponding electrode on the surface of the driving circuit board; and step S19, removing the second supporting substrate, and forming a second electrode on the exposed surface of the light emitting structure of the light emitting diode.

Fig. 2A to 2L are schematic process diagrams of the present embodiment.

Referring to step S10, shown in fig. 2A, a first support substrate 20 is provided, the first support substrate 20 including a support layer 201 and a surface epitaxial layer 202. Wherein the support layer 201 is selected from any one of sapphire, silicon carbide, silicon, gallium nitride and aluminum nitride, and the epitaxial layer 202 on the surface is selected from any one of GaN/InGaN and AlN/GaN/InGaN; the support layer 201 may be selected from one of GaAs, GaP, and InP, and the epitaxial layer 202 may be selected from GaAs, AlGaAs, AlInP, or any combination thereof; the support layer 201 may be selected from any one of sapphire, silicon carbide, silicon, gallium nitride, and aluminum nitride, and the epitaxial layer 202 may be selected from GaN, AlN, AlGaN, or any combination thereof. Wherein epitaxial layer 202 may be formed by Metal Organic Chemical Vapor Deposition (MOCVD), Molecular Beam Epitaxy (MBE), sputtering (Sputter), or combinations thereof.

Referring to step S11, as shown in fig. 2B and 2C, a patterned insulating layer 21 is formed on the surface of the first supporting substrate 20, wherein the hollowed-out portion of the patterned insulating layer has an open sidewall. The patterned insulating layer 21 may be formed by a deposition process to form a continuous mask layer 211 of a material selected from the group consisting of SiO_x、SiN_xAnd TiO_xAnd any one of the insulating substances is processed, and then a hollow-out pattern is formed on the continuous mask layer 211 through photoetching and etching processes, so that the patterned insulating layer 21 is manufactured. The deposition mode adopts atomic layer deposition, Plasma Enhanced Chemical Vapor Deposition (PECVD), magnetron sputtering or combination mode. The hollow pattern can be selected from any one of a circle, a square, a rectangle or a polygon. The lateral etching speed can be controlled to be gradually reduced by adjusting the etching process parameters in the etching process so as to form an opening shape with a large upper part and a small lower part, or the blocking effect of the photoresist on the side wall is gradually weakened in the etching process by adjusting the thickness of the photoresist so as to form the opening shape.

Referring to step S12, as shown in fig. 2D and 2E, a light reflecting layer 22 is grown on the sidewall of the hollow portion of the patterned insulating layer 21. In an embodiment of the present invention, the step of forming the light reflecting layer 22 on the side wall may specifically adopt the following steps, and fig. 3A to 3C are process diagrams of the following steps. Step S121, growing a continuous light reflecting layer 221 on the surface of the patterned insulating layer; step S122, referring to fig. 3A, a continuous photoresist layer 222 is coated on the surface of the continuous light reflecting layer 221; step S123, referring to fig. 3B, exposing, developing and removing the photoresist layer at the bottom of the hollow portion, and leaving the photoresist layer covered by the side surface of the sidewall; step S124, referring to fig. 3C, the light reflective layer exposed at the bottom is removed by etching, and the light reflective layer 22 grown on the sidewall of the hollow portion of the patterned insulating layer is remained. In step S123, the photoresist layer on the surface of the patterned insulating layer 21 can be selectively removed or remained by development. If the development removal is selected, in step S124, the portion of the corresponding light reflective layer is also etched and removed; if retention is selected, then in step S124, the portion of the corresponding light reflecting layer is also retained. In step S124, the etching process may be slightly extended to generate an over-etching effect, which may remove the light reflective layer at the bottom of the sidewall photoresist.

The light reflecting layer material is selected from any one or more of hafnium dioxide/silicon dioxide alternating lamination, silicon dioxide/tantalum oxide alternating lamination, niobium pentoxide (Nb2O5) and silicon dioxide alternating lamination, zirconium dioxide and silicon dioxide alternating lamination, and silicon dioxide/titanium dioxide alternating lamination. Or a metal layer (e.g., Al, Ag, etc.) having a light reflecting property, which covers an insulating material (e.g., SiO2, etc.), and is formed by any one or a combination of atomic layer deposition, Plasma Enhanced Chemical Vapor Deposition (PECVD), electron beam evaporation, and magnetron sputtering.

Then, the light reflecting layer on the surface of the patterned insulating layer is removed by photolithography and etching processes, and the side wall light reflecting layer is remained, thereby forming the light reflecting layer 22 only on the side wall. The light reflecting layer 22 serves to prevent light crosstalk caused by light emission from the side walls of adjacent chips. Meanwhile, light emitted to the side wall by the chip is reflected, and the luminous efficiency and the brightness of the chip are improved. The light reflection layer arranged obliquely can also play a role in light condensation, and the light emitting efficiency is further improved.

Referring to step S13, as shown in fig. 2F, a light emitting structure 23 of the led is grown at the hollow of the patterned insulating layer 21. A typical light emitting structure 23 should include an N-type layer, a multiple quantum well light emitting layer, and a P-type layer, preferably the P-type layer may include a P-type electron blocking layer therein, and the filling method preferably uses a Metal Organic Chemical Vapor Deposition (MOCVD), Molecular Beam Epitaxy (MBE), or the like process. The light-emitting layer is blue light: in with different In composition and thickness_xGa_1-xN and GaN are alternately laminated to form the multi-quantum well. The light-emitting layer is ultraviolet light or deep ultraviolet light: from Al of different Al composition and thickness_xGa_1-xN and Al_yGa_1-yN is formed by alternately laminating multiple quantum wells. The light emitting layer is red: of different composition and thickness (AlGa)_xIn_1-xPand (AlGa)_yIn_1-yP is formed by alternately stacking multiple quantum wells. Because the patterned insulating layer 21 is made of SiO_x、SiN_xAnd TiO_xAnd the like, so that the phenomenon of epitaxial growth cannot occur on the surface of the substrate through process control, the epitaxy only occurs on the surface of the support substrate 20 exposed through the hollow part, the hollow part is further filled to form the light-emitting structure 23, and the light-emitting structure array of the light-emitting diode which is isolated from each other is formed in situ, so that the damage of the side wall of the chip caused by the fact that the table top of the chip can be formed only by photoetching and etching in the conventional chip manufacturing process is avoided. Meanwhile, the subsequent cutting process can be performed along the insulating portion of the patterned insulating layer 21, thereby further avoiding the damage of the cutting process to the side wall of the chip. Therefore, the damage to the side wall of the chip generated in the etching and cutting processes can be avoided in the whole chip preparation process, and the non-radiative recombination center of the side wall of the chip is reduced, so that the non-radiative recombination probability of the side wall of the chip is reduced, and the luminous efficiency of the chip is improved.

Referring to step S14, as shown in fig. 2G, a second support substrate 29 is provided. The second support substrate 29 is a temporary support, and may be made of any one of a wide range of materials, such as sapphire, silicon carbide, silicon, gallium nitride, aluminum nitride, GaAs, GaP, and InP, or any other conventional material that can serve as a mechanical support.

Referring to step S15, the light emitting structure 23 is bonded to the second supporting substrate 29 as shown in fig. 2H.

Referring to step S16, as shown in fig. 2I, the first supporting substrate 20 is removed to expose the light emitting structure 23 of the light emitting diode.

Referring to step S17, as shown in fig. 2J, the first electrode 24 is formed on the exposed surface of the light emitting structure 23 of the light emitting diode. The first electrode 24 is made of a metal material, and may be a multilayer metal stack, such as an alloy of one or any combination of Ag, Cr, Al, Ni, Ti, Pt, Ge, AuGe, Pd, and Au, and is implemented by a process method such as electron beam evaporation (e-beam evaporation). Since the opposite surface of the light emitting layer is a light emitting surface, the light emitting layer is preferably made of a metal material having a characteristic of totally reflecting light emitted from the light emitting layer. And has ohmic characteristics and current spreading characteristics (such as ITO). Further, the upper surface of the light emitting structure 23 not covered by the first electrode 24 may be provided with a light reflecting layer structure, such as a distributed bragg reflector DBR, an omni-directional reflector ODR (not shown).

Referring to step S18, as shown in fig. 2K, the second supporting substrate 29 already provided with the light emitting structure is bonded to a driving circuit board 25, and the first electrode 24 of the light emitting structure 23 of the light emitting diode corresponds to an electrode on the surface of the driving circuit board (not shown). After the steps are completed, the inclined direction of the obliquely arranged light reflection layer is ensured to face the light emitting surface, so that the light condensation effect can be achieved, and the light emitting efficiency is improved. After bonding, insulating protective substances such as reflective white glue and the like can be optionally filled. The driving circuit substrate 25 may be a silicon, glass or PCB substrate using a TFT process or a CMOS process. Since the light emitting structure 23 of the led is already fabricated on the supporting substrate 20, the light emitting structure can be transferred to the driving circuit board 25 in batch by using a substrate-to-substrate bonding method, which reduces the cost compared with transferring one by one after cutting. And if the quantum dot light conversion material is continuously coated on the surface after the second supporting substrate 29 is removed, the light-emitting structure 23 can be combined with quantum dot light conversion materials with different colors to realize full-color display, and the whole transfer can be completed in the step. For example, when the light emitting structure of the light emitting diode emits blue light, the light emitting structure can be integrated by spraying, printing or printing red and green quantum dots and the like on the array light emitting structure, so that full-color display is realized; when the light-emitting structure of the light-emitting diode emits purple light or ultraviolet light, the light-emitting structure can be integrated on the array chip by spraying, printing or printing red, green and blue quantum dots and the like, so that full-color display is realized.

Referring to step S16, as shown in fig. 2L, the second supporting substrate 29 is removed, and a second electrode 26 is formed on the surface of the light emitting structure 23 of the exposed led. The second support substrate 29 may be removed by wet or dry etching. The second electrode 26 is made of metal material, the utility model discloses do not do specifically and restrict metal material, because this face is the play plain noodles, therefore preferred metal material has the characteristics of carrying out the total transmission to the light that the luminescent layer sent.

The micro light-emitting diode array obtained after the implementation of the steps comprises the following steps: the patterned insulating layer is provided with a hollow part, and the side wall of the hollow part is covered with the light reflecting layer; the light-emitting structure of the light-emitting diode is arranged in the hollow part, and a first electrode and a second electrode are respectively arranged on two opposite surfaces of the light-emitting structure; and the driving circuit substrate is bonded on the surface of the first electrode of the light-emitting structure of the light-emitting diode, and the first electrode of the light-emitting structure of the light-emitting diode is aligned and bonded with the corresponding electrode on the surface of the driving circuit substrate.

After the steps are completed, selective cutting can be carried out according to the requirements, and the cutting can be carried out along the insulating part of the patterned insulating layer 21, so that the damage to the side wall of the chip caused by cutting in the chip splitting process of a conventional chip is avoided, the non-radiative recombination center and the non-radiative recombination probability of the side wall of the chip are reduced, and the internal quantum efficiency and the luminous efficiency of the chip are improved.

An embodiment of the invention is given below in conjunction with specific materials:

providing a GaAs-based AlGaAs first support substrate;

SiO adopting PECVD evaporation on substrate surface₂Manufacturing an insulating layer in a square grid shape;

growing Al/SiO on the sidewall of the hollow part of the patterned insulating layer by adopting an electron beam evaporation method₂A light reflecting layer formed by the omnidirectional reflector ODR;

growing a light-emitting structure of the light-emitting diode at the hollow part of the graphical insulating layer by adopting an MOCVD selective area growth method: the N-type layer is silicon-doped AlInP, the light-emitting layer is composed of GaInP/AlGaInP multi-quantum well MQW, and the P-type layer is composed of magnesium-doped AlInP/GaP;

and silicon bonding the structure with a second support substrate.

By means of H₃PO₄:H₂O₂:H₂Removing the first supporting substrate by an O wet method;

manufacturing a first electrode consisting of AuGe/Au on the surface of the exposed light-emitting structure of the light-emitting diode by adopting an electron beam evaporation method;

bonding the second supporting substrate which is provided with the light-emitting structure and the first electrode with a CMOS driving circuit substrate;

after the driving substrate is protected by insulating substances, removing the second supporting substrate silicon;

and manufacturing a second electrode consisting of ITO/Au on the exposed surface of the light-emitting structure of the light-emitting diode by adopting a sputtering method.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, a plurality of improvements and decorations can be made without departing from the principle of the present invention, and these improvements and decorations should also be regarded as the protection scope of the present invention.

Claims (5)

1. A micro light emitting diode array, comprising:

a support substrate;

the light emitting structure of the light emitting diode is arranged on the surface of the supporting substrate;

the insulating layer surrounds the light-emitting structure, a light reflecting layer is arranged between the insulating layer and the side wall of the light-emitting structure, and the light reflecting layer is obliquely arranged so as to have the function of gathering emergent light of the light-emitting diode.

2. The micro light emitting diode array of claim 1, wherein the support substrate comprises a support layer and a surface epitaxial layer, the support layer is selected from any one of sapphire, silicon carbide, silicon, gallium nitride and aluminum nitride, the surface epitaxial layer is selected from any one of GaN/InGaN and AlN/GaN/InGaN; or the supporting layer is selected from one of GaAs, GaP and InP, and the epitaxial layer is selected from AlGaAs, AlInP or any combination thereof; or the supporting layer is selected from any one of sapphire, silicon carbide, silicon, gallium nitride and aluminum nitride, and the epitaxial layer is selected from GaN, AlN, AlGaN or any combination thereof; wherein the epitaxial layer is formed by metal organic chemical vapor deposition, molecular beam epitaxy, or a combination thereof.

3. The micro light-emitting diode array of claim 1, wherein the insulating layer is made of a material selected from the group consisting of SiO_x、SiN_xAnd TiO_xAnd is formed by atomic layer deposition, Plasma Enhanced Chemical Vapor Deposition (PECVD), magnetron sputtering, or a combination thereof.

4. The micro light-emitting diode array as claimed in claim 1, wherein the light reflective layer is composed of two alternating layers of insulating materials with different refractive indexes, selected from hafnium oxide/silicon dioxide, silicon dioxide/tantalum oxide, and niobium pentoxide (Nb)₂O₅) And any one or more of silicon dioxide alternate lamination, zirconium dioxide and silicon dioxide alternate lamination and silicon dioxide/titanium dioxide alternate lamination, and adopting any one of atomic layer deposition, plasma enhanced chemical vapor deposition, electron beam evaporation and magnetron sputteringOne or more of the above-mentioned materials.

5. The micro light-emitting diode array as claimed in claim 1, wherein the light reflecting layer is composed of a metal layer having light reflecting properties covering the insulating material.

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