CN116137309A

CN116137309A - Chip transfer method

Info

Publication number: CN116137309A
Application number: CN202111358629.XA
Authority: CN
Inventors: 戴广超; 马非凡; 曹进; 张雪梅; 王子川
Original assignee: Chongqing Kangjia Photoelectric Technology Research Institute Co Ltd
Current assignee: Chongqing Kangjia Photoelectric Technology Research Institute Co Ltd
Priority date: 2021-11-16
Filing date: 2021-11-16
Publication date: 2023-05-19
Also published as: WO2023087921A1

Abstract

The application relates to a chip transfer method. The chip transfer method comprises the following steps: providing a growth substrate with a plurality of LED chips formed on the surface; transferring the LED chip to a transient substrate, wherein one side of the LED chip far away from the transient substrate is provided with a naked first surface; forming a supporting layer connected with the LED chip on the transient substrate, and forming a through channel in the transient substrate; a force is applied to the first surface to transfer each LED chip to the target substrate through the through-channel. By adopting the chip transfer method, the transfer to the target substrate is realized by utilizing the gravity of the LED chip, and the chip transfer yield can be greatly improved; moreover, by using the chip transfer process, the repair of the missing chip at the target position can be realized by applying the acting force to the LED chip by corresponding the position of the through channel to the target position of the pre-repair.

Description

Chip transfer method

Technical Field

The application relates to the technical field of chip mass transfer, in particular to a chip transfer method.

Background

The Micro light emitting diode (Micro Light Emitting Diode, micro-LED) is an emerging display technology, and compared with the conventional display technology, the display with the Micro-LED technology as a core has the characteristics of high response speed, self-luminescence, high contrast, long service life, high photoelectric efficiency and the like.

In the Micro-LED industry technology, a mass transfer technology is a core key technology, and a large number of Micro-LED crystal grains are transferred to a target substrate or a circuit through high-precision equipment. The huge transfer cost, yield and precision are key to the success of huge transfer.

Currently, micro-LED mass transfer technology is divided into multiple technical families according to principle, including electrostatic force, vanderwav force, magnetic force, laser selective transfer, fluid transfer, and direct transfer. After the chips are transferred onto the substrate, gaps are easy to appear at the target positions, so that the chip transfer yield is affected, and the missing chips at the target positions also need to be repaired.

Disclosure of Invention

In view of the above-mentioned shortcomings of the prior art, an object of the present application is to provide a chip transfer method, which aims to solve the problem that the chip transfer process in the prior art affects the chip transfer yield.

A chip transfer method comprising the steps of:

providing a growth substrate with a plurality of LED chips formed on the surface;

transferring the LED chip to a transient substrate, wherein one side of the LED chip far away from the transient substrate is provided with a naked first surface;

forming a supporting layer connected with the LED chip on the transient substrate, and forming a through channel in the transient substrate;

a force is applied to the first surface to transfer each LED chip to the target substrate through the through-channel.

According to the chip transferring method, the LED chips are transferred to the transient substrate, the side, far away from the transient substrate, of the LED chips is provided with the exposed first surface, the support layer connected with the LED chips is formed on the transient substrate, the through channels are formed in the transient substrate, and then acting force is applied to the first surface, so that the LED chips are transferred to the target substrate through the through channels, the transfer to the target substrate is realized by utilizing the gravity of the LED chips, and the chip transferring yield can be greatly improved; moreover, by using the chip transfer process, the repair of the missing chip at the target position can be realized by applying the acting force to the LED chip by corresponding the position of the through channel to the target position of the pre-repair.

Optionally, each LED chip includes an epitaxial structure, a first electrode and a second electrode, where the first electrode and the second electrode are located on a side of the epitaxial structure away from the growth substrate; after the step of transferring the LED chip to the transient substrate, the epitaxial structure is located on a side of the first electrode and the second electrode away from the transient substrate, and the epitaxial structure has a first surface. The light emitting device can be in a flip-chip structure, so that the electrode is not required to be connected with the display backboard by a lead, the distance between the light emitting devices is reduced, and the PPI of the display panel is improved.

Optionally, the step of transferring the LED chip to the transient substrate comprises: bonding the LED chip on the transient substrate through the adhesive layer so that the growth substrate is positioned on one side of the LED chip far away from the transient substrate; the growth substrate is peeled off to expose the first surface. The material for forming the adhesive layer can be conventional photo-curing adhesive or thermal-curing adhesive in the prior art, the adhesive layer covering the transient substrate is formed through a coating process, and the adhesive layer can be removed through heat treatment or illumination in the follow-up process, so that the process is simple and easy to implement.

Optionally, before the step of forming the support layer connecting the first surface of the portion on the transient substrate, the chip transfer method further includes the steps of: and removing the adhesive layer positioned between the adjacent LED chips on the transient substrate. Through getting rid of the glue film between the adjacent LED chip, in the step of follow-up formation supporting layer, the supporting layer can be connected with transient state base plate direct connection to make the supporting layer can be connected on transient state base plate more firmly.

Optionally, the LED chip has a first side surrounding the first surface, and in the step of forming a support layer on the transient substrate connecting the LED chip, the support layer connects part of the first surface and/or at least part of the first side. The supporting layer and the LED chip are flexible in connection mode, and the supporting layer can be connected with the first surface of the LED chip only, can be connected with the first side of the LED chip only and can be connected with the first surface and the first side of the LED chip simultaneously.

Optionally, the step of forming a support layer connecting the first surface of the portion on the transient substrate includes: forming a support preparation layer wrapping the LED chip on the transient substrate; patterning the support preparation layer on the first surface so that at least part of the first surface is exposed, and forming a support layer by the rest of the support preparation layer. The support preparation layer wrapping the LED chip is formed firstly, and then the LED chip is etched to have a naked stress surface, so that the formed support layer can be firmly connected to the transient substrate, and the process is simple and easy to implement.

Optionally, the step of patterning the support preparation layer on the first surface comprises: the support preparation layer on the first surface is etched so that the remaining support preparation layer surrounds the edge of the first surface. Through forming the supporting layer around and connect at the first surface edge of LED chip, not only can make the supporting layer connect on transient state base plate more firmly, can also make to have bigger naked region in the first surface to have bigger atress area, and then can realize the transfer of LED chip to the target base plate through exerting less effort in the follow-up.

Optionally, a support preparation layer is formed on the transient substrate using a PECVD process. Compared with other deposition processes in the prior art, the PECVD (plasma enhanced chemical vapor deposition) process can effectively avoid the influence on the device performance caused by the deposition material entering the epitaxial structure of the LED chip.

Optionally, the material forming the support preparation layer includes any one or more of silicon oxide, silicon nitride, and silicon oxynitride. The material is used as the material for forming the supporting layer subsequently, so that the supporting layer can be firmly connected to the transient substrate, and the process is mature and the cost is low.

Optionally, the step of forming the through-channel in the transient substrate includes: and patterning the transient substrate to form a plurality of through channels corresponding to the LED chips one by one in the transient substrate, wherein the minimum cross-sectional dimension of each through channel is larger than the maximum cross-sectional dimension of each LED chip in the direction parallel to the transient substrate. The LED chips are separated from the supporting layer under the action of external force, and are transferred to the target substrate by gravity, and through forming the penetrating channels corresponding to the LED chips one by one, the LED chips can be prevented from overturning in the falling process, and the transfer yield is greatly improved.

Alternatively, the transient substrate includes any one of a silicon substrate, a silicon carbide substrate, and a gallium arsenide substrate. Compared with the prior art, the transient substrate of the material type has smaller hardness than the substrate type such as sapphire and stripping, and the difficulty in forming the through channel by etching can be reduced by adopting the optional substrate type.

Optionally, the depth of the through channel is H ₁ In the depth direction of the through channel, the height of the LED chip is H ₂ ，H1＞H ₂ . In the process of transferring the chip at the preset position on the target substrate, the LED chips may be arranged at other positions corresponding to different through channels on the target substrate, so that the influence on the chips at other positions when the chip is repaired at the preset position can be avoided by enabling the depth of the through channels and the height of the LED chips to meet the relation.

Optionally, the step of applying a force to the first surface to transfer each LED chip to the target substrate through the through-channel includes: providing a target substrate, wherein one side surface of the target substrate is provided with a target area; the transient substrate is arranged on the target substrate, so that the LED chip is positioned on one side of the transient substrate far away from the target substrate and corresponds to the target area; a force is applied to the first surface to transfer the LED chip through the through-channel to the target area. The conventional chip transfer process in the prior art may cause a vacancy in a part of the target area on the target substrate, that is, the LED chip corresponding to the target position is not transferred, and at this time, the above steps may be used to repair the chip.

Drawings

Fig. 1 is a schematic structural diagram of a substrate after an epitaxial structure is formed on a growth substrate in a chip transfer method according to an embodiment of the present application;

FIG. 2 is a schematic diagram of a substrate after forming an ITO conductive layer on the surface of the N-type semiconductor layer in the epitaxial structure shown in FIG. 1;

FIG. 3 is a schematic structural diagram of a substrate after forming a reflective layer covering the epitaxial structure on the growth substrate shown in FIG. 2 and forming extraction holes in the reflective layer penetrating to the ITO conductive layer and the P-type semiconductor layer, respectively;

FIG. 4 is a schematic diagram of a structure of a substrate after forming a first lead portion connected to the ITO conductive layer and a second lead portion connected to the P-type semiconductor layer in the lead hole shown in FIG. 3, respectively;

FIG. 5 is a schematic diagram of a structure of the temporary substrate shown in FIG. 4 after covering the temporary substrate with a glue layer;

fig. 6 is a schematic structural diagram of a substrate after bonding an LED chip on a transient substrate by the adhesive layer shown in fig. 5;

FIG. 7 is a schematic view of the substrate after the growth substrate shown in FIG. 6 is peeled off to expose the first surface;

FIG. 8 is a schematic diagram of a structure of the transient substrate of FIG. 7 after removing the adhesive layer between adjacent LED chips;

FIG. 9 is a schematic diagram of a structure of a substrate after forming a support preparation layer for encapsulating an LED chip on the transient substrate shown in FIG. 8;

FIG. 10 is a schematic view of the structure of the substrate after patterning the support preparation layer on the first surface shown in FIG. 9 to form a support layer;

FIG. 11 is a schematic diagram of the structure of the transient substrate of FIG. 10 after patterning to form a through-channel;

FIG. 12 is a schematic view of the substrate after removing the adhesive layer shown in FIG. 11;

fig. 13 is a schematic structural view of the LED chip shown in fig. 12 disposed on one side of the target substrate through the supporting layer;

FIG. 14 is a schematic view of a structure of a substrate after applying a force to the first surface shown in FIG. 13 to transfer each LED chip to a target substrate through a through-channel;

fig. 15 is a schematic structural diagram of a rear substrate in which the LED chip shown in fig. 13 is located on a side of the transient substrate away from the target substrate and corresponds to the target region;

fig. 16 is a schematic structural view of the substrate after applying a force to the first surface shown in fig. 15 to transfer the LED chip to the target area through the through-channel.

Reference numerals illustrate:

10-LED chips; 101-a first surface; 110-an epitaxial structure; a 111-N type semiconductor layer; 112-an active layer; 113-P type semiconductor layer; 120-a first electrode; 121-an ITO conductive layer; 122-a first lead-out; 130-a second electrode; 140-a reflective layer; 20-growing a substrate; 30-a transient substrate; 310-through channels; 40-glue layer; 50-a support layer; 510-supporting a preparation layer; 60-target substrate; 610-target area.

Detailed Description

In order to facilitate an understanding of the present application, a more complete description of the present application will now be provided with reference to the relevant figures. Preferred embodiments of the present application are shown in the accompanying drawings. This application may, however, be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

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

As described in the background section, at present, after a chip is transferred onto a substrate by using a macro transfer technology of Micro-LEDs, a vacancy is easily generated at a target position, so that the chip transfer yield is affected, and a missing chip at the target position needs to be repaired.

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

The inventor of the present application studied on the above problems and proposed a chip transfer method comprising the steps of:

Exemplary embodiments of a chip transfer method according to the present application will be described in more detail below with reference to the accompanying drawings. These exemplary embodiments may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. It should be appreciated that these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of these exemplary embodiments to those skilled in the art.

First, a growth substrate 20 having a plurality of LED chips 10 formed on the surface thereof is provided, as shown in fig. 1 to 4.

In some embodiments, the growth substrate 20 includes, but is not limited to, a glass sheet, a quartz sheet, a gallium arsenide substrate, a sapphire substrate, and the like.

Illustratively, each LED chip 10 includes an epitaxial structure 110, a first electrode 120, and a second electrode 130, the first electrode 120 and the second electrode 130 being located on a side of the epitaxial structure 110 remote from the growth substrate 20; after the step of transferring the LED chip 10 to the transient substrate 30, the epitaxial structure 110 is located at a side of the first electrode 120 and the second electrode 130 remote from the transient substrate 30, and the epitaxial structure 110 has a first surface 101.

The LED chip 10 may be a Micro-LED chip, a Min-LED (mini light emitting diode) chip, or a larger-sized LED chip. The LED chip 10 is an Organic Light-Emitting Diode (OLED) chip, for example. In addition, the structure type and the color type of the LED chip 10 are not limited, the LED chip can be a trichromatic (red, green and blue) chip or an LED chip with a color other than trichromatic, the light-emitting device can be of a normal structure, a flip-chip structure, a vertical structure or a transverse structure, and the LED chip 10 with the flip-chip structure is connected with the display backboard without a lead wire, so that the distance between the light-emitting devices is reduced, and the PPI of the display panel is improved.

In some embodiments of the present application, providing a growth substrate 20 having a plurality of LED chips 10 formed on a surface thereof includes the steps of: forming an epitaxial structure 110 on the growth substrate 20, the epitaxial structure 110 including an N-type semiconductor layer 111, an active layer 112, and a P-type semiconductor layer 113, as shown in fig. 1; a first electrode 120 and a second electrode 130 are formed to be connected to the epitaxial structure 110, respectively, as shown in fig. 2 to 4.

In the above-described embodiment, the LED chip 10 may be a GaN-based LED. Illustratively, the N-type semiconductor layer 111 is an N-type GaN layer, the active layer 112 is a quantum well layer, and the P-type semiconductor layer 113 is a P-type GaN layer.

In some embodiments of the present application, the step of forming the first electrode 120 and the second electrode 130 respectively connected to the epitaxial structure 110 may include: an ITO (indium tin oxide) conductive layer is formed on the surface of the N-type semiconductor layer 111 as shown in fig. 2; forming a reflective layer 140 covering the epitaxial structure 110 on the growth substrate 20, and forming extraction holes penetrating to the ITO conductive layer 121 and the N-type semiconductor layer 111, respectively, in the reflective layer 140, as shown in fig. 3; a first lead portion 122 connected to the ITO conductive layer 121 and a second lead portion connected to the N-type semiconductor layer 111 are formed in the lead holes, respectively, as shown in fig. 4.

In the above embodiment, the ITO conductive layer 121 has high conductivity and visible light transmittance, and the use of the ITO conductive layer 121 as a part of the first electrode 120 can improve the light emission luminance of the LED chip 10. Illustratively, the ITO conductive layer 121 has a thickness of

In the above embodiment, the reflective layer 140 is used to increase the light emitting brightness of the LED chip 10, and the reflective layer 140 may have a DBR (distributed bragg reflection) structure, which is generally composed of two materials with different refractive indexes alternately arranged, and the optical thickness of each material is 1/4 of the central reflection wavelength. The reflective layer 140 includes silicon oxide layers and silicon nitride layers alternately stacked to have a thickness of 1 to 4 μm, for example.

In the above-described embodiment, the first and second lead-out

portions

122 and 140 may be formed in the reflective layer 140 using a dry etching process. Illustratively, the reflective layer 140 is an alternating stack of silicon oxide and silicon nitride layers, and the dry etching process has an etching gas of CF ₄ O ₂ Ar。

In the above embodiment, the first lead-out portion 122 may be a part of the first electrode 120, and together with the ITO conductive layer 121, form the first electrode 120 of the LED chip 10, the second lead-out portion may be directly used as the second electrode 130 of the LED chip 10, and the first lead-out portion 122 and the second lead-out portion may be conventional conductive materials in the prior art. Illustratively, the first and second lead-out

portions

122 and 122 are formed on the reflective layer 140 using a negative photoresist lithography process and an etching process, and then the lead-out electrodes are evaporated using an evaporation process to a thickness of 1-4 μm, and the first and second lead-out

portions

122 and 122 are formed after photoresist is removed.

After the step of providing the growth substrate 20 with the LED chip 10 formed on the surface, the LED chip 10 is transferred to the transient substrate 30, the side of the LED chip 10 remote from the transient substrate 30 having the exposed first surface 101, as shown in fig. 5 to 7.

In some embodiments of the present application, the step of transferring the LED chip 10 to the transient substrate 30 includes: bonding the LED chip 10 on the transient substrate 30 through the adhesive layer 40 so that the growth substrate 20 is located at a side of the LED chip 10 away from the transient substrate 30, as shown in fig. 5 and 6; the growth substrate 20 is peeled off to expose the first surface 101 as shown in fig. 7. The material for forming the glue layer 40 may be conventional photo-glue or thermal glue in the prior art, the glue layer 40 covering the transient substrate 30 is formed by a coating process, and the glue layer 40 can be removed by heat treatment or illumination in the following process, so that the process is simple and easy to implement.

In the above embodiment, the glue layer 40 may be formed on the surface of the transient substrate 30 through a coating process. Illustratively, the glue layer 40 is a BCB (benzocyclobutene) glue layer.

The step of bonding the LED chip 10 to the temporary substrate 30 through the adhesive layer 40 may have different embodiments, so that the support layer 50 formed later and the LED chip 10 have different connection manners.

In an alternative embodiment, the LED chip 10 has a second surface opposite to the first surface 101 and a first side surrounding the first surface 101, and the step of bonding the LED chip 10 to the temporary substrate 30 by the glue layer 40 comprises: the glue layer 40 is made to completely cover the second surface and the first side of the LED chip 10, and the LED chip 10 is fixed on the transient substrate 30 by the glue layer 40 on the second surface and the first side.

In the above-described embodiment, after the growth substrate 20 is peeled off, since only the first surface 101 of the LED chip 10 is exposed, the support layer 50 formed later may be connected only to the above-described first surface 101.

In the above embodiment, the adhesive layer 40 can completely cover the second surface and the first side of the LED chip 10 by coating the adhesive material on the surface of the transient substrate 30 and inserting the side of the LED chip 10 having the second surface into the adhesive material, so that the first side of the LED chip 10 is completely wrapped by the adhesive material, and then curing the adhesive material to form the adhesive layer 40 connecting the transient substrate 30 and the LED chip 10.

In another alternative embodiment, the LED chip 10 has a second surface opposite to the first surface 101 and a first side surrounding the first surface 101, and the step of bonding the LED chip 10 to the temporary substrate 30 by the glue layer 40 comprises: the adhesive layer 40 is made to entirely cover the second surface of the LED chip 10 and partially cover the first side of the LED chip 10, and the LED chip 10 is fixed on the temporary substrate 30 through the adhesive layer 40 on the second surface and the first side.

In the above embodiment, after the growth substrate 20 is peeled off, since the first surface 101 and a portion of the first side of the LED chip 10 are exposed, the subsequently formed support layer 50 may be simultaneously connected to the first surface 101 and the first side.

In the above embodiment, the glue layer 40 may be formed by coating the glue material on the surface of the transient substrate 30, inserting the side of the LED chip 10 having the second surface into the glue material, so that the first side of the LED chip 10 is partially wrapped by the glue material, and then curing the glue material to form the glue layer 40 connecting the transient substrate 30 and the LED chip 10, so that the glue layer 40 completely covers the second surface of the LED chip 10 and partially covers the first side of the LED chip 10.

In another alternative embodiment, the LED chip 10 has a second surface opposite to the first surface 101 and a first side surrounding the first surface 101, and the step of bonding the LED chip 10 to the temporary substrate 30 by the glue layer 40 comprises: the glue layer 40 is made to completely cover the second surface of the LED chip 10, and the LED chip 10 is fixed on the transient substrate 30 by the glue layer 40 on the second surface.

In the above embodiment, after the growth substrate 20 is peeled off, since the first surface 101 and the first side of the LED chip 10 are completely exposed, the subsequently formed support layer 50 may be connected to the first surface 101 and the first side, and the support layer 50 may completely cover the first side of the LED chip 10, thereby achieving a more stable connection with the LED chip 10.

In the above embodiment, the adhesive layer 40 can be formed by coating the adhesive material on the surface of the transient substrate 30 and bonding the adhesive material with the second surface of the LED chip 10, and then curing the adhesive material to form the adhesive layer 40 connecting the transient substrate 30 and the LED chip 10, so that the adhesive layer 40 completely covers the second surface of the LED chip 10.

It should be noted that in some other embodiments of the present application, the LED chip 10 may also be transferred to the transient substrate 30 by other bonding methods, such as eutectic bonding, van der waals bonding, etc.

In some embodiments of the present application, the transient substrate 30 described above includes any one of a silicon substrate, a silicon carbide substrate, and a gallium arsenide substrate. Compared with the prior art, the transient substrate of the material type has smaller hardness than the substrate type such as sapphire and stripping, and the difficulty in forming the through channel by etching can be reduced by adopting the optional substrate type.

In some embodiments of the present application, the growth substrate 20 is peeled by a laser peeling process, so that the first surface 101 is exposed, and the process conditions of the laser peeling process may be reasonably set according to the type of the growth substrate 20, which is not described in detail in the present application.

In some embodiments of the present application, the glue layer 40 on the transient substrate 30 between adjacent LED chips 10 is removed, as shown in fig. 8. By removing the glue layer 40 between adjacent LED chips 10, the support layer 50 can be directly connected to the temporary substrate 30 in the subsequent step of forming the support layer 50, so that the support layer 50 can be more firmly connected to the temporary substrate 30.

After the step of transferring the LED chip 10 to the temporary substrate 30, a support layer 50 connecting the LED chip 10 is formed on the temporary substrate 30, as shown in fig. 9 and 10. The support layer 50 is connected to the LED chip 10, and at least a portion of the first surface 101 of the LED chip 10 is exposed, and the exposed first surface 101 serves as a stress surface for subsequently applying a force to the LED chip 10 to separate the LED chip 10 from the support layer 50.

In general, the support layer 50 does not have deformability or is poor in deformability, so that the support layer 50 is prevented from being opened when the LED chip 10 tends to be far away from the support layer 50 due to the pressure of the operating bodyThe excessive deformation continues to follow the LED chip 10, but the LED chip 10 can be more cleanly dropped off from the supporting layer 50. In this embodiment, the support layer 50 may be a brittle material with a failure stress below or well below the yield limit of the material. Exemplary materials for the support layer 50 include, but are not limited to, siO ₂ (silica), graphite, metals (including metals with a higher carbon content, such as pig iron, etc.).

The support layer 50 and the LED chip 10 may have different connection modes, which are not specifically limited in this application. For example, the LED chip 10 has a first side surface surrounding the first surface 101, and in the step of forming the support layer for connecting the LED chip 10 on the transient substrate 30, the support layer 50 may be connected to only a portion of the first surface 101 of the LED chip 10, may be connected to only a portion of the first side surface of the LED chip 10, and may be connected to both a portion of the first surface 101 and at least a portion of the first side surface of the LED chip 10.

In some embodiments of the present application, the step of forming the support layer 50 connecting the LED chips 10 on the transient substrate 30 includes: forming a support preparation layer 510 wrapping the LED chip 10 on the transient substrate 30, as shown in fig. 9; the support preparation layer 510 on the first surface 101 is patterned so that at least a portion of the first surface 101 is exposed, and the remaining support preparation layer 510 constitutes the support layer 50, as shown in fig. 10. The support preparation layer 510 wrapping the LED chip 10 is formed first, and then the LED chip 10 is etched to have a bare stress surface, so that the formed support layer 50 can be firmly connected to the transient substrate 30, and the process is simple and easy to implement.

In the above embodiment, the step of patterning the support preparation layer 510 on the first surface 101 may include: the support preparation layer 510 on the first surface 101 is etched such that the remaining support preparation layer 510 surrounds the edge of the first surface 101. By forming the support layer 50 around and attached to the edge of the first surface 101 of the LED chip 10, not only can the support layer 50 be more firmly attached to the transient substrate 30, but also a larger exposed area in the first surface 101 can be provided, thereby having a larger stressed area, and further the transfer of the LED chip 10 to the target substrate 60 can be subsequently achieved by applying a smaller force.

The remaining support preparation layer 510 surrounds the edge of the first surface 101, and the exposed area of the first surface 101 not covered by the support preparation layer 510 serves as a force-bearing surface for subsequently applying a force to the LED chip 10 to separate the LED chip 10 from the support layer 50. The shape of the exposed area in the first surface 101 includes, but is not limited to, circular, oval, diamond, triangular, rectangular, etc., but may be trapezoidal, pentagram, and other regular or irregular shapes.

In the step of forming the support preparation layer 510 on the transient substrate 30, deposition processes such as PVD (Physical Vapor Deposition ), CVD (Chemical Vapor Deposition, chemical vapor deposition), PECVD (Plasma Enhanced Chemical Vapor Deposition ), EV (vacuum evaporating, evaporation) and the like may be employed.

Illustratively, a PECVD process is used to form a support preparation layer 510 on the transient substrate 30. Compared with other deposition processes in the prior art, the PECVD (plasma enhanced chemical vapor deposition) process can effectively avoid the influence on the device performance caused by the deposition material entering the epitaxial structure 110 of the LED chip 10.

In the above-described embodiment, the shape of the LED chip 10 may be defined such that the support preparation layer 510 deposited on the transient substrate 30 covers only the first surface 101 of the LED chip 10. For example, the shape of the LED chip 10 is inverted trapezoid, and the material supporting the preliminary layer 510 falls only on the first surface 101 of the LED chip 10 during deposition, and does not contact the first side surface of the LED chip 10.

Illustratively, the material forming the support preparation layer 510 includes any one or more of silicon oxide, silicon nitride, and silicon oxynitride. The adoption of the material as the material for forming the supporting layer 50 later not only can firmly connect the supporting layer 50 on the transient substrate 30, but also has mature process and lower cost.

After the step of forming the support layer 50 connecting the LED chips 10 on the transient substrate 30, a through via 310 is formed in the transient substrate 30, as shown in fig. 11 and 12.

The transient substrate 30 has a through channel 310 formed therein, and it is needless to say that the through channel 310 is a channel penetrating both side surfaces of the transient substrate 30. The number of the through channels 310 may be one or more, and the plurality of through channels 310 may be arranged in an array in the transient substrate 30 according to the number of the LED chips 10 to be transferred, but those skilled in the art will understand that in other examples, other embodiments may be used for the arrangement of the transient substrate 30. Since the through-channels 310 are used to transfer the LED chips 10 passing therethrough to the target substrate, the arrangement of the through-channels 310 in the transient substrate 30 is related to the arrangement of the LED chips 10. In the case that the entire LED chip 10 needs to be transferred to the target back plate (driving substrate) in a huge amount, the arrangement of the through channels 310 in the transient substrate 30 can refer to the arrangement mode of the receiving areas of the chips on the target back plate; in addition, since the LED chip 10 is directly transferred from the growth substrate to the transient substrate, the arrangement of the through channels 310 in the transient substrate 30 can also refer to the arrangement of the LED chip 10 on the growth substrate.

It should be noted that the form of the through-channel 310 is not limited in this application, and for example, the cross-section of the through-channel 310 may be circular, elliptical, parallelogram, etc., as long as the through-channel 310 is capable of passing through the LED chip 10 and transferring to the target substrate.

In some embodiments of the present application, the step of forming the through-channel 310 in the transient substrate 30 includes: the transient substrate 30 is patterned to form a plurality of through channels 310 in the transient substrate 30 in one-to-one correspondence with the LED chips 10, and a minimum cross-sectional size of each through channel 310 is larger than a maximum cross-sectional size of each LED chip 10 in a direction parallel to the transient substrate 30, as shown in fig. 11. The LED chip 10 is separated from the supporting layer 50 under the action of external force, and is transferred to the target substrate 60 due to gravity, and the through channels 310 corresponding to the LED chips 10 one by one are formed, so that the LED chips 10 can be prevented from being turned over in the falling process, and the transfer yield is greatly improved.

To further prevent the LED chip 10 from being greatly displaced or even flipped during the passage through the through-channel 310, the cross-sectional dimension of the through-channel 310 may be made relatively small, e.g., in some examples of this embodiment, the cross-sectional dimension of the through-channel 310 is only slightly larger than the cross-sectional dimension of the LED chip 10.

In some embodiments of the present application, the depth of the through channel is H ₁ In the depth direction of the through channel, the height of the LED chip is H ₂ ，H ₁ ＞H ₂ . In the process of transferring the chip at the preset position on the target substrate, the LED chips may be arranged at other positions corresponding to different through channels on the target substrate, so that the influence on the chips at other positions when the chip is repaired at the preset position can be avoided by enabling the depth of the through channels and the height of the LED chips to meet the relation.

When the glue layer 40 is used to transfer the LED chip 10 to the transient substrate 30, after the step of forming the through-channel 310, the glue layer 40 needs to be removed to connect the LED chip 10 with the through-channel 310, as shown in fig. 12.

After the step of forming the support layer 50 having the through-channels 310 and connecting the LED chips 10, the LED chips 10 are disposed on the target substrate 60 side through the support layer 50, and a force is applied to the first surface 101 to transfer each LED chip 10 to the target substrate 60 through the through-channels 310, as shown in fig. 13 and 14. Illustratively, a force may be applied to the first surface 101 of the LED chip 10 by a thimble.

It will be appreciated that the first surfaces 101 of different LED chips 10 may be simultaneously applied with a force to transfer a plurality of LED chips 10 onto the target substrate 60, for example, a plurality of pins simultaneously push down different LED chips 10, thereby improving the transfer efficiency of the LED chips 10.

In general, after the LED chip 10 is transferred to the target substrate 60 in a huge amount, there may be a case where a vacancy occurs in a portion of the target positions on the target substrate 60, that is, the LED chip 10 corresponding to the target positions is not transferred, and there may also be a case where a portion of the LED chips are poorly bonded after the LED chip 10 is bonded, at which time the defective LED chip on the target substrate 60 may be identified by detecting after the LED chip 10 is bonded to the target substrate 60, and then removed from the target substrate 60, and chip repair may be performed at the vacancy or the position where the defective LED chip is removed.

To effect repair of the chips at the target locations, in some embodiments of the present application, the step of applying a force to the first surface 101 to transfer each LED chip 10 to the target substrate 60 through the through-channel 310 further comprises: providing a target substrate 60, wherein one side surface of the target substrate 60 is provided with a target area 610; disposing the transient substrate 30 on the target substrate 60 such that the LED chip 10 is located on a side of the transient substrate 30 away from the target substrate 60 and corresponds to the target region 610, as shown in fig. 15; a force is applied to the first surface 101 to transfer the LED chip 10 to the target area 610 through the through-channel 310, as shown in fig. 16. When the target area 610 is empty or a location where a defective LED chip is removed, repair of the chip at the target area 610 can be achieved using the above steps.

It is to be understood that the application of the present application is not limited to the examples described above, but that modifications and variations can be made by a person skilled in the art from the above description, all of which modifications and variations are intended to fall within the scope of the claims appended hereto.

Claims

1. A chip transfer method, comprising the steps of:

transferring the LED chip to a transient substrate, wherein one side of the LED chip far away from the transient substrate is provided with a bare first surface;

and applying a force to the first surface to transfer each LED chip to a target substrate through the through channel.

2. The chip transfer method of claim 1, wherein each of the LED chips includes an epitaxial structure, a first electrode, and a second electrode, the first electrode and the second electrode being located on a side of the epitaxial structure remote from the growth substrate;

after the step of transferring the LED chip to the transient substrate, the epitaxial structure is located on a side of the first electrode and the second electrode away from the transient substrate, and the epitaxial structure has the first surface.

3. The chip transfer method of claim 1, wherein transferring the LED chip to the transient substrate comprises:

bonding the LED chip on the transient substrate through an adhesive layer so that the growth substrate is positioned on one side of the LED chip far away from the transient substrate;

and stripping the growth substrate to expose the first surface.

4. The chip transfer method of claim 3, wherein prior to the step of forming the support layer on the transient substrate that connects portions of the first surface, the chip transfer method further comprises the steps of:

and removing the adhesive layer positioned between the adjacent LED chips on the transient substrate.

5. The chip transfer method of any one of claims 1 to 4, wherein the LED chip has a first side surrounding the first surface, and wherein in the step of forming the support layer on the transient substrate connecting the LED chip, the support layer connects a portion of the first surface and/or at least a portion of the first side.

6. The chip transfer method of claim 5, wherein the step of forming the support layer connecting the LED chips on the transient substrate comprises:

forming a support preparation layer wrapping the LED chip on the transient substrate;

patterning the support preparation layer on the first surface so that at least part of the first surface is exposed, and the rest of the support preparation layer constitutes the support layer.

7. The chip transfer method of any one of claims 1 to 4, wherein the step of forming the through-channel in the transient substrate comprises:

and patterning the transient substrate to form a plurality of through channels corresponding to the LED chips one by one in the transient substrate, wherein the minimum cross-sectional dimension of each through channel is larger than the maximum cross-sectional dimension of each LED chip in the direction parallel to the transient substrate.

8. The chip transfer method of any one of claims 1 to 4, wherein the transient substrate comprises any one of a silicon substrate, a silicon carbide substrate, and a gallium arsenide substrate.

9. The chip transfer method according to any one of claims 1 to 4, wherein the depth of the through channel is H ₁ In the depth direction of the through channel, the height of the LED chip is H ₂ ，H ₁ ＞H ₂ 。

10. The chip transfer method according to any one of claims 1 to 4, wherein the step of applying a force to the first surface to transfer each of the LED chips to a target substrate through the through-passage includes:

providing a target substrate, wherein one side surface of the target substrate is provided with a target area;

the transient substrate is arranged on the target substrate, so that the LED chip is positioned on one side of the transient substrate far away from the target substrate and corresponds to the target area;

a force is applied to the first surface to transfer the LED chip through the through-channel to the target area.