CN219937070U

CN219937070U - LED wafer, transfer substrate and display device

Info

Publication number: CN219937070U
Application number: CN202320647685.3U
Authority: CN
Inventors: 谈江乔; 吴双; 叶海生; 宣玮; 何剑
Original assignee: Xiamen Changelight Co Ltd
Current assignee: Xiamen Changelight Co Ltd
Priority date: 2023-03-29
Filing date: 2023-03-29
Publication date: 2023-10-31
Anticipated expiration: 2033-03-29

Abstract

The utility model provides an LED wafer, a transfer substrate and a display device. In the subsequent transfer process, when the LED wafer and the transfer substrate are bonded in an alignment mode, the pad layer is used for relieving warping caused by epitaxial growth of the wafer, so that LED core particles have good consistency and are flatly bonded with the sensing layer, a gas discharge space is formed between the sensing layer and the substrate, waste gas (such as nitrogen gas) generated in the subsequent substrate stripping process can be uniformly discharged from the gas discharge space, the influence on the wafer is avoided, and meanwhile, the consistency and the stripping yield of the LED core particles in the substrate stripping process are ensured, so that the repairability and the transfer yield of the wafer are improved.

Description

LED wafer, transfer substrate and display device

Technical Field

The utility model relates to the field of light emitting diodes, in particular to an LED wafer, a transfer substrate and a display device.

Background

Microcomponent technology refers to an array of tiny-sized components integrated at high density on a substrate. At present, micro-pitch light emitting diode (Micro LED) technology is becoming a popular research, and industry is expecting high quality Micro-component products to enter the market. High quality micro-pitch light emitting diode products can have a profound impact on conventional display products such as LCD/OLED that are already on the market. Micro-Led technology, i.e., led miniaturization and matrixing technology, refers to a technology of integrating a high-density, micro-sized Led array on one chip to reduce the distance of pixel points from millimeter level to micrometer level. As Micro-Led has superior performance, the advantages of high brightness, high yield, high reliability, small volume, long service life and the like of the inorganic LED are inherited, and the application in the display field is wider and wider.

The Micro-LED is peeled off from the epitaxial growth substrate by the following steps: firstly, bonding the Micro-LEDs with a transfer substrate by adopting a temporary bonding material, and then peeling the Micro-LEDs from an epitaxial growth substrate by adopting a laser peeling technology to transfer the Micro-LEDs to the transfer substrate. However, since the growth temperature of Micro-LEDs on an epitaxial growth substrate is up to about 1000 ℃, and the material of the LED crystal layer is usually gallium nitride, the lattice parameter and the thermal expansion coefficient of gallium nitride and the epitaxial growth substrate are greatly different, and when the temperature is reduced from high temperature to room temperature after epitaxial growth, the substrate warpage phenomenon occurs, as shown in fig. 1. The transfer substrate has good flatness, so that when the transfer substrate is bonded with Micro-LEDs on an epitaxial growth substrate, the flatness difference of the transfer substrate and the Micro-LEDs is obvious, so that the areas of the LED core particles coated by bonding materials are uneven, and particularly the areas of the LED core particles at high positions are extremely large (as shown in figure 2); therefore, in the subsequent stripping process of the growth substrate, the exhaust gas discharge is influenced, the stripping yield is low, the subsequent transfer yield is influenced, and huge workload and waste of production cost are caused for the production process.

In view of this, the present inventors have specifically devised an LED wafer, a transfer substrate, and a display device, which are produced thereby.

Disclosure of Invention

The utility model aims to provide an LED wafer, a transfer substrate and a display device, which are used for solving the problems of stripping and low transfer yield caused by wafer warpage.

In order to achieve the above purpose, the technical scheme adopted by the utility model is as follows:

an LED wafer comprises a substrate and a plurality of LED core grains formed by epitaxial growth on the surface of the substrate, wherein each LED core grain comprises a horizontal structure LED core grain or a vertical structure LED core grain; wherein, a pad layer is arranged on the surface of one side of the substrate, which is away from the LED core particle.

Preferably, the pad layer is disposed at an edge of the wafer.

Preferably, the width of the pad layer is L, the diameter of the wafer is D, D/50< L < D/10, and the height of the pad layer is not less than the warpage height of the wafer.

Preferably, the pad layers are distributed on the edge of the wafer in a lattice manner in a triangle shape, a round shape or a square block shape;

or, the pad layers are uniformly distributed on the edge of the wafer in an arc-shaped mode.

Preferably, the elevated layer comprises a layer of material having a hardness greater than 0.3Gpa and being resistant to high temperatures above 100 ℃.

Preferably, the pad layer comprises a polyimide-based material layer, and/or an epoxy-based material layer, and/or a metal oxide layer, and/or a silicon nitride layer, and/or a silicon oxide layer.

Preferably, the LED die comprises a gallium nitride based LED die.

The utility model also provides a transfer substrate for transferring the LED wafer, which comprises a temporary substrate and an induction layer arranged on the surface of the temporary substrate.

Preferably, the sensing layer includes any one of a thermal sensing material, an ultraviolet light sensing material, a laser sensing material, a radiation sensing material, a plasma sensing material, and a microwave sensing material.

Preferably, the sensing layer is formed on the surface of the temporary substrate by spin coating or knife coating or spraying.

A display device comprising a plurality of pixels arranged on a support substrate, the pixels being obtained by bonding the LED wafer of any one of the above and the transfer substrate of any one of the above in alignment and then transferring to a target substrate;

in the bonding process, the pad layer is used for relieving warpage caused by epitaxial growth of the wafer, so that the LED core particles have consistency and are flatly bonded with the sensing layer, and a gas exhaust space is formed between the sensing layer and the substrate.

According to the technical scheme, the LED wafer provided by the utility model is characterized in that the surface of one side of the substrate, which is far away from the LED core particle, is provided with the raised layer, and further, the raised layer is arranged around the edge of the wafer. Meanwhile, the utility model also provides a transfer substrate for transferring the LED wafer, which comprises a temporary substrate and an induction layer arranged on the surface of the temporary substrate. In the subsequent transfer process, when the LED wafer and the transfer substrate are bonded in an alignment mode, the pad layer is used for relieving warping caused by epitaxial growth of the wafer, so that LED core particles have good consistency and are flatly bonded with the sensing layer, a gas discharge space is formed between the sensing layer and the substrate, waste gas (such as nitrogen gas) generated in the subsequent substrate stripping process can be uniformly discharged from the gas discharge space, the influence on the wafer is avoided, and meanwhile, the consistency and the stripping yield of the LED core particles in the substrate stripping process are ensured, so that the repairability and the transfer yield of the wafer are improved.

Secondly, by setting up: d/50< L < D/10 (wherein the width of the pad layer is L and the diameter of the wafer is D). The leveling area inside the wafer is not affected while the pad layer is ensured to fully support the wafer; and the height of the pad layer is not less than the warping height of the wafer, so that the warping of the sheet source can be flattened.

The utility model also provides an LED display device, wherein the pixels are obtained by bonding the LED wafer described in any one of the above and the transfer substrate described in any one of the above in an alignment manner and transferring the bonded LED wafer to the target substrate, and the LED display device has a simple structure and is convenient to operate and realize.

Drawings

In order to more clearly illustrate the embodiments of the present utility model or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only embodiments of the present utility model, and that other drawings can be obtained according to the provided drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic view of warpage caused by epitaxial growth of a wafer in the prior art;

FIG. 2 is a schematic diagram of a prior art structure of a warp wafer bonded to a transfer substrate in alignment;

FIG. 3 is a schematic view of a back side structure of a wafer according to an embodiment of the present utility model;

fig. 4 is a schematic structural diagram of a wafer with LED dies with vertical structures according to embodiment 1;

fig. 5 is a schematic structural diagram of a transfer substrate according to embodiment 1;

fig. 6 to 11 are schematic structural diagrams corresponding to the transfer method provided in embodiment 1.

Fig. 12 is a schematic structural diagram of a wafer with a horizontal LED die according to embodiment 2;

fig. 13 is a schematic structural diagram of a transfer substrate according to embodiment 2;

fig. 14 to 19 are schematic structural diagrams corresponding to the transfer method provided in embodiment 2.

The symbols in the drawings illustrate:

1. a substrate; 2. the LED chip comprises an LED core particle, 3 parts of a pad layer, 4 parts of a temporary substrate, 5 parts of a sensing layer, 6 parts of a gas discharge space, 7 parts of a first mask, 71 parts of a non-sensitive area, 72 parts of a sensitive area, 8 parts of a sensitive source.

Detailed Description

In order to make the contents of the present utility model more clear, the contents of the present utility model will be further described with reference to the accompanying drawings. The present utility model is not limited to this specific embodiment. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

Example 1

As shown in fig. 3, an LED wafer includes a substrate 1 and a plurality of LED dies 2 formed on the surface of the substrate 1 by epitaxial growth, where each LED die 2 includes a vertical structure LED die 2; wherein, a side surface of the substrate 1 facing away from the LED core particle 2 is provided with a lifting layer 3.

It is to be noted that the type of the substrate 1 is not limited in the present embodiment, and for example, the substrate 1 includes any one of sapphire, silicon carbide, silicon, gallium nitride, aluminum nitride, gallium arsenide; meanwhile, the specific structure and material constitution of the LED core 2110 are not limited in this embodiment.

On the basis of the above-described embodiments, in one embodiment of the present utility model, the LED die 2 includes at least a first type semiconductor layer, an active region, and a second type semiconductor layer stacked in this order on the surface of the substrate 1, a first electrode forming ohmic contact with the first type semiconductor layer, and a second electrode forming ohmic contact with the second type semiconductor layer; note that the specific material types of the first type semiconductor layer, the active region, and the second type semiconductor layer may also be not limited in this embodiment, for example, the first type semiconductor layer may be, but not limited to, an N-GaN layer, and correspondingly, the second type semiconductor layer may be, but not limited to, a P-GaN layer; meanwhile, the specific arrangement positions of the first electrode and the second electrode are not limited, and the first electrode and the first type semiconductor layer can form ohmic contact, and the second electrode and the second type semiconductor layer can form ohmic contact;

based on the above embodiment, in one embodiment of the present utility model, the LED die 2 is a horizontal LED die 2, and at this time, the first electrode is deposited in the recess to form ohmic contact with the first semiconductor layer by forming the recess and the mesa through the opening, and the second electrode is deposited on the mesa to form a horizontal distribution state of the first electrode and the second electrode.

Based on the above embodiments, in one embodiment of the present utility model, the LED die 2 is a vertical LED die 2, and at this time, the first electrode and the second electrode are respectively located on the upper surface and the lower surface of the LED die 2 and form ohmic contact with the first semiconductor layer and the second semiconductor layer, so as to form a vertical distribution state of the first electrode and the second electrode.

On the basis of the above embodiments, in one embodiment of the present utility model, the pad layer 3 is disposed at the edge of the wafer.

Based on the above embodiments, in one embodiment of the present utility model, the width of the pad layer 3 is L, the diameter of the wafer is D, D/50< L < D/10, and the height of the pad layer 3 is not less than the warpage height of the wafer.

Based on the above embodiments, in one embodiment of the present utility model, the pad layers 3 are distributed on the edge of the wafer in a triangular, round or square lattice manner;

or, as shown in fig. 4, the pad layers 3 are uniformly distributed on the edge of the wafer in an arc-shaped manner.

On the basis of the above-described embodiments, in one embodiment of the present utility model, the elevated layer 3 includes a material layer having high hardness and high temperature resistance. Specifically, the elevated layer comprises a material layer with hardness greater than 0.3Gpa and high temperature resistance above 100 ℃.

On the basis of the above-described embodiments, in one embodiment of the present utility model, the pad layer 3 includes a polyimide-based material layer, and/or an epoxy-based material layer, and/or a metal oxide layer, and/or a silicon nitride layer, and/or a silicon oxide layer.

On the basis of the above embodiments, in one embodiment of the present utility model, the LED die 2 includes a gallium nitride-based LED die 2.

As shown in fig. 5, the embodiment of the present utility model further provides a transfer substrate for transferring the LED wafer described in any one of the above, which includes a temporary substrate 4 and a sensing layer 5 disposed on a surface of the temporary substrate 4.

On the basis of the above embodiment, in one embodiment of the present utility model, the sensing layer 5 includes any one of a thermal sensing material, an ultraviolet light sensing material, a laser sensing material, a radiation sensing material, a plasma sensing material, and a microwave sensing material.

On the basis of the above embodiments, in one embodiment of the present utility model, the sensing layer 5 is formed on the surface of the temporary substrate 4 by spin coating or knife coating or spray coating.

The utility model also provides a transfer method, which comprises the following steps:

step S01, as shown in fig. 3 and 4, providing an LED wafer as described in any one of the above;

step S02, as shown in FIG. 5, providing a transfer substrate according to any one of the above;

step S03, as shown in fig. 6 and fig. 7, bonding the LED wafer in step S01 and the transfer substrate formed in step S02 in an aligned manner, in the bonding process, the raised layer 3 is used to alleviate warpage caused by epitaxial growth of the wafer, so that the bonded LED core 2 has consistency and forms a flat bond with the sensing layer 5, and a gas exhaust space 6 is formed between the sensing layer 5 and the substrate 1;

in this embodiment, since the pad layer 3 may alleviate the warpage of the wafer caused by epitaxial growth, so that the wafer has good consistency of the LED core 2, after the LED wafer in step S01 is aligned and bonded with the transfer substrate formed in step S02, the LED core 2 and the sensing layer 5 are bonded flatly.

Note that the bonding process is not limited in this embodiment, for example, electrostatic bonding, thermal bonding, or the like.

Step S04, as shown in FIG. 8, removing the pad layer 3;

note that, the present embodiment is not limited to the removal method of the raised layer 3, and specifically, the raised layer 3 may be removed by wet etching or dry etching.

Step S05, as shown in fig. 9, removing the substrate 1;

on the basis of the above-described embodiments, in one embodiment of the present utility model, removing the substrate 1 includes: the substrate 1 is removed by a laser lift-off process, but the present utility model is not limited thereto.

When the substrate 1 is removed (e.g., laser lift-off), it is necessary to perform dicing lift-off by means of an assist gas (e.g., oxygen or nitrogen or air or argon, etc.), and in the embodiment of the present utility model, the assist gas may be exhausted through the gas exhaust space 6 to avoid affecting the wafer.

Step S06, selectively damaging the sensing layer 5 through a mask and combining with a corresponding sensing source, so that the corresponding LED die 2 naturally drops to the target substrate.

In one embodiment of the present utility model, step S06 is specifically performed by the following process:

step one, as shown in fig. 10, a photoresist layer is smeared on one side of the temporary substrate 4, which is far away from the LED core particle 2, so as to form a first photoresist layer; exposing and developing the first photoresist layer to form a first photoresist pattern on the side, away from the LED core particles 2, of the temporary substrate 4 as a first mask 7, wherein the first mask 7 comprises a sensitive area 72 and a non-sensitive area 71;

specifically, in one embodiment of the present utility model, when the sensing layer 5 is made of a photo-sensing material, the sensitive area 72 of the first mask 7 is a light-transmitting area, and the non-sensitive area 71 is a light-impermeable area.

Step two, as shown in fig. 11, selectively destroying the induction layer 5 by the induction source through the sensitive area 72 of the first mask 7, so that the induction layer 5 is decomposed corresponding to the sensitive area 72 of the first mask 7, and the corresponding LED core particles 2 naturally drop to the target substrate;

based on the first mask 7 in the first step, the light source is selectively destroyed to the sensing layer 5 through the light-transmitting area of the first mask 7, so that the sensing layer 5 is decomposed corresponding to the light-transmitting area of the first mask 7, and the corresponding LED core 2 naturally falls to the target substrate.

On the basis of the above embodiment, in one embodiment of the present utility model, step S06 further includes removing the defective LED die 2 and the substrate 1 simultaneously by a masking process, wherein after masking the array of vertical structure LED die 2 to mark the defective LED die 2, removing the defective LED die 2 and the substrate 1 simultaneously; it should be noted that, in other embodiments of the present utility model, the array of the LED dies 2 with the horizontal structure may be masked to remove the defective LED dies 2 and the substrate 1 at the same time, which is not limited. Meanwhile, the specific process of masking the defective LED die 2110 is not limited, and reference is made specifically to the masking process shown in this step.

It should be emphasized that the type of the induction source is not limited in the embodiment of the present utility model, as long as the induction source is satisfied to correspond to the material sensitivity of the induction layer 5, and damage to the induction layer 5 can be achieved by the induction source.

On the basis of the above-described embodiments, in one embodiment of the present utility model, the specific material type of the target substrate is not limited in this embodiment as long as the self-adhesive material layer is satisfied, for example, the target substrate includes any one of a blue film, a thin film, a UV film, a pyrolytic film, and a silicone gel.

The utility model also provides a display device which comprises a plurality of pixels arranged on the supporting substrate, wherein the pixels are obtained by bonding the LED wafer and the transfer substrate in an alignment manner by the transfer method and then transferring the bonded LED wafer and the transfer substrate to a target substrate.

As can be seen from the above technical solution, in the LED wafer provided by the present utility model, the raised layer 3 is disposed on the surface of the side of the substrate 1 facing away from the LED core 2, and further, the raised layer 3 is disposed around the edge of the wafer. Meanwhile, the utility model also provides a transfer substrate for transferring the LED wafer, which comprises a temporary substrate 4 and a sensing layer 5 arranged on the surface of the temporary substrate 4. In the subsequent transfer process, when the LED wafer and the transfer substrate are aligned and bonded, the raised layer 3 is used for relieving warpage caused by epitaxial growth of the wafer, so that the LED core particles 2 have good consistency and are flatly bonded with the sensing layer 5, and a gas discharge space 6 is formed between the sensing layer 5 and the substrate 1, so that waste gas (such as nitrogen gas) generated in the subsequent substrate 1 stripping process can be uniformly discharged from the gas discharge space 6, the influence on the wafer is avoided, and meanwhile, the consistency and the stripping yield of the LED core particles 2 in the substrate 1 stripping process are ensured, thereby improving the repairability and the transfer yield of the wafer.

The utility model also provides a transfer method, which has the advantages of low production cost, simple operation, easy realization and convenient production while realizing the technical effects.

Example 2

The present embodiment differs from embodiment 1 only in that in this embodiment, the LED core 2 is a horizontally structured LED core 2.

Fig. 12 is a schematic structural diagram of a wafer with a horizontal LED die according to the present embodiment;

fig. 13 is a schematic structural diagram of a transfer substrate according to the present embodiment;

fig. 14 to 19 are schematic structural diagrams corresponding to the transfer method according to the present embodiment.

In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other.

It is further noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that an article or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such article or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in an article or apparatus that comprises such element.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present utility model. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the utility model. Thus, the present utility model is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

The LED wafer is characterized by comprising a substrate and a plurality of LED core grains formed by epitaxial growth on the surface of the substrate, wherein each LED core grain comprises a horizontal structure LED core grain or a vertical structure LED core grain; and a heightening layer is arranged on the surface of one side of the substrate, which is away from the LED core particle, and the heightening layer is arranged at the edge of the wafer.
2. The LED wafer of claim 1, wherein the height of the raised layer is L, the diameter of the wafer is D, D/50< L < D/10, and the height of the raised layer is not less than the warp height of the wafer.
3. The LED wafer of claim 1, wherein said raised layers are distributed in a triangular or round or square pattern on the edge of said wafer;

or, the pad layers are uniformly distributed on the edge of the wafer in an arc-shaped mode.
4. The LED wafer of claim 1, wherein said elevated layer comprises a layer of material having a hardness greater than 0.3Gpa that is resistant to temperatures above 100 ℃.
5. The LED wafer of claim 1, wherein said lift-off layer comprises a polyimide-based material layer, and/or an epoxy-based material layer, and/or a metal oxide layer, and/or a silicon nitride layer, and/or a silicon oxide layer.
6. A transfer substrate for transferring the LED wafer according to any one of claims 1 to 5, comprising a temporary substrate and a sensing layer disposed on a surface of the temporary substrate.
7. The transfer substrate of claim 6, wherein the sensing layer is formed on the surface of the temporary substrate by spin coating or doctor blading or spray coating.
8. A display device comprising a plurality of pixels arranged on a support substrate, wherein the pixels are obtained by bonding the LED wafer according to any one of claims 1 to 5 and the transfer substrate according to any one of claims 6 to 7 in alignment and transferring to a target substrate;

in the bonding process, the pad layer is used for relieving warpage caused by epitaxial growth of the wafer, so that the LED core particles have consistency and are flatly bonded with the sensing layer, and a gas exhaust space is formed between the sensing layer and the substrate.
9. The display device of claim 8, wherein the target substrate is a self-adhesive material layer comprising any one of a blue film, a thin film, a UV film, and a pyrolytic film.