WO2023077504A1

WO2023077504A1 - Chip structure, chip structure manufacturing method, and chip transfer method

Info

Publication number: WO2023077504A1
Application number: PCT/CN2021/129253
Authority: WO
Inventors: 王斌; 萧俊龙; 汪楷伦; 范春林; 汪庆
Original assignee: 重庆康佳光电技术研究院有限公司
Priority date: 2021-11-08
Filing date: 2021-11-08
Publication date: 2023-05-11

Abstract

A chip structure (100), comprising a chip (10) and an anti-collision structure (20). The chip (10) comprises an epitaxial layer (11) and a pad (12) provided on one side of the epitaxial layer (11). The anti-collision structure (20) comprises a flexible layer (21) provided on one side of the epitaxial layer (11) facing away from the pad (12), and an air cavity (22) formed by the protrusion of the flexible layer (21) towards a direction away from the epitaxial layer (11). The chip structure (100) can protect the chip in a chip transfer process, thereby improving the yield of chip transfer.

Description

Chip structure, preparation method of chip structure and chip transfer method

technical field

The present application relates to the technical field of semiconductors, in particular to a chip structure, a method for preparing the chip structure, and a chip transfer method.

Background technique

The statements herein merely provide background information related to the present application and do not necessarily constitute exemplary techniques.

Light Emitting Diode (LED) display panel is a widely used display device, which has the advantages of high brightness, wide dynamic range, long service life, stability and reliability.

The LED display panel includes: a driving backplane, and LED chips arrayed on the driving backplane. In the process of manufacturing LED display panels, the mass transfer of LED chips is a key step. Mass transfer refers to the precise transfer of millions or even tens of millions of LED chips from the growth substrate to the driver backplane.

However, the quantity of LED chips transferred is large and the transfer is difficult. During the transfer process of the LED chips, some LED chips are likely to be damaged, thereby affecting the transfer yield of the LED chips.

Therefore, how to protect the LED chips during the mass transfer process to improve the transfer yield of the LED chips is an urgent problem to be solved.

Contents of the invention

According to various embodiments of the present application, a chip structure, a method for preparing the chip structure, and a chip transfer method are provided.

A chip structure includes: a chip and an anti-collision structure. The chip includes an epitaxial layer and pads arranged on one side of the epitaxial layer. The anti-collision structure includes: a flexible layer disposed on the side of the epitaxial layer away from the pad, and an air cavity formed by the flexible layer protruding away from the epitaxial layer.

In the above chip structure, an anti-collision structure is provided on one side of the chip, specifically on the side of the epitaxial layer away from the bonding pad. The anti-collision structure is composed of a flexible layer and an air cavity formed by the flexible layer protruding away from the epitaxial layer. In this way, the raised flexible layer and the air cavity can be used to effectively protect the chip, so as to prevent a large number of chips from colliding with each other during the transfer process, which is beneficial to improving the transfer yield of the chip.

A method for preparing a chip structure, comprising the following steps.

A chip is prepared on the growth base, and the chip includes an epitaxial layer and a pad disposed on a side of the epitaxial layer away from the growth base. The chip is transferred from the growth substrate to the temporary substrate, and the epitaxial layer is located on the side of the pad away from the temporary substrate. A sacrificial layer is formed covering a localized area of the epitaxial layer. A flexible layer is formed, and the flexible layer covers the sacrificial layer and the surface of the epitaxial layer located in the peripheral area of the sacrificial layer. Decompose the sacrificial layer and generate gas; the gas makes the flexible layer bulge away from the epitaxial layer, forming an air cavity.

A chip transfer method, comprising the following steps.

Transfer the chip structure to a liquid to form a chip mix solution. A driving backplane is provided, and an auxiliary board is provided on the side of the driving backplane where the driving electrodes are provided; the auxiliary board includes: a chip positioning channel corresponding to the driving electrodes. The chip mixed solution is injected or drained into the chip positioning channel, and the chip structure is aligned and suspended in the chip positioning channel. Remove the liquid in the positioning channel of the chip. The flexible layer is removed, and the chip is dropped along the chip positioning channel until the pad is aligned and in contact with the driving electrode.

The details of one or more embodiments of the application are set forth in the accompanying drawings and the description below. Other features, objects and advantages of the present application will be apparent from the description, drawings and claims.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments or exemplary technologies of the present application, the following will briefly introduce the accompanying drawings that need to be used in the descriptions of the embodiments or exemplary technologies. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present application. Those skilled in the art can also obtain the drawings of other embodiments according to these drawings without creative work.

Fig. 1 is a schematic diagram of a chip structure provided by an embodiment;

FIG. 2 is a schematic structural diagram of another chip provided by an embodiment;

Figure 3(a), Figure 3(b) and Figure 3(c) are schematic diagrams of a region A where a flexible layer is bonded to an epitaxial layer provided in some embodiments;

Fig. 4 is a flowchart of a method for preparing a chip structure provided by an embodiment;

Figure 5(a) is a schematic cross-sectional view of the structure obtained in step S110 provided by an embodiment;

Figure 5(b) is a schematic cross-sectional view of the structure obtained in step S120 provided by an embodiment;

Figure 5(c) is a schematic cross-sectional view of the structure obtained in step S130 provided by an embodiment;

Figure 5(d) is a schematic cross-sectional view of the structure obtained in step S140 provided by an embodiment;

Figure 5(e) is a schematic cross-sectional view of the structure obtained in step S150 provided by an embodiment;

Figure 6(a) is a schematic cross-sectional view of the structure obtained in steps S131 and S132 provided by an embodiment;

Figure 6(b) is a schematic cross-sectional view of the structure obtained in step S133 provided by an embodiment;

Figure 7(a) is a schematic cross-sectional view of the structure obtained in steps S141 and S142 provided by an embodiment;

Figure 7(b) is a schematic cross-sectional view of the structure obtained in step S143 provided by an embodiment;

FIG. 8 is a flow chart of a chip transfer method provided by an embodiment;

Figure 9(a) is a schematic cross-sectional view of the structure obtained in step S210 provided by an embodiment;

Figure 9(b) is a schematic cross-sectional view of the structure obtained in step S220 provided by an embodiment;

Figure 9(c) is a schematic cross-sectional view of the structure obtained in step S230 provided by an embodiment;

Figure 9(d) is a schematic cross-sectional view of the structure obtained in step S240 provided by an embodiment;

Figure 9(e) is a schematic cross-sectional view of the structure obtained in step S250 provided by an embodiment;

Fig. 10 is a schematic top view of an auxiliary plate provided in an embodiment;

Fig. 11 is a kind of auxiliary plate shown in Fig. 10 along the schematic sectional view of I-I ';

Figure 12(a), Figure 12(b) and Figure 12(c) are schematic top views of different auxiliary plates provided in other embodiments;

Fig. 13 is a schematic cross-sectional view of an LED substrate obtained after removing the auxiliary board and the flexible layer provided by an embodiment.

Detailed ways

In order to make the purpose, technical solution and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present application, and are not intended to limit the present application.

The LED display panel is a widely used display device, which has the advantages of high brightness, wide dynamic range, long service life, stability and reliability, and the like.

When performing mass transfer, the number of LED chips that need to be transferred is very large, and the difficulty of transfer is also very high. Taking a 4K screen as an example, the number of LED chips that need to be transferred is as high as 24 million. Even if 10,000 are transferred at a time, it needs to be repeated 2,400 times. In 2400 repetitions, it is difficult to ensure that each LED chip can be transferred to the driver backplane intact, that is, some LED chips may be damaged. For example, chips are broken due to collisions between chips. This will affect the transfer yield of the LED chip.

Based on this, the present application hopes to provide a solution capable of solving the above-mentioned technical problems, the details of which will be described in subsequent embodiments.

Please refer to FIG. 1 and FIG. 2 , the embodiment of the present application provides a chip structure 100, including: a chip 10 and an anti-collision structure 20. in,

The chip 10 includes an epitaxial layer 11 and a bonding pad 12 disposed on one side of the epitaxial layer 11 .

The anti-collision structure 20 includes: a flexible layer 21 disposed on a side of the epitaxial layer 11 away from the pad 12 , and an air cavity 22 formed by the flexible layer 21 protruding away from the epitaxial layer 11 .

In the embodiment of the present application, the chip 10 can be prepared on a growth substrate. In this way, the pad 12 is formed on the side of the epitaxial layer 11 away from the growth substrate. After the chip 10 is transferred from the growth substrate to the temporary substrate, the pad 12 will be located on the side of the epitaxial layer 11 close to the temporary substrate, that is, the transfer of the chip is realized by connecting the pad 12 to the temporary substrate. In this way, the surface of the epitaxial layer 11 away from the temporary substrate is exposed, and a sacrificial layer can be formed on a local area of the exposed surface. After the sacrificial layer is formed, the flexible layer 21 may be continuously formed, so that the flexible layer 21 covers the sacrificial layer and the surface of the epitaxial layer 11 located in the peripheral area of the sacrificial layer. Subsequently, after decomposing the sacrificial layer and generating gas, the gas can make the flexible layer 21 protrude in a direction away from the epitaxial layer to form an air cavity 22 .

In the above chip structure 100 , the anti-collision structure 20 is provided on one side of the chip 10 , specifically on the side of the epitaxial layer 11 away from the bonding pad 12 . The anti-collision structure 20 is composed of a flexible layer 21 and an air cavity formed by the flexible layer 21 protruding away from the epitaxial layer 11 . In this way, the chip 10 can be effectively protected by the raised flexible layer 21 and the air cavity 22 , so as to prevent a large number of chips 10 from colliding with each other during the transfer process, which is beneficial to improve the transfer yield of the chip 10 .

The chip structure 100 provided in the embodiment of the present application is suitable for chip transfer through fluid self-assembly. Specifically, the chip structure 100 is transferred into a liquid to form a chip mixed solution. A driving backplane is provided, and an auxiliary board is provided on the side of the driving backplane where the driving electrodes are provided; the auxiliary board includes: a chip positioning channel corresponding to the driving electrodes. The chip mixed solution is injected or drained into the chip positioning channel, and the chip structure 100 is aligned and suspended in the chip positioning channel. Remove the liquid in the positioning channel of the chip. The flexible layer 21 is removed, and the chip 10 is dropped along the chip positioning channel until the pads 12 are aligned and contacted with the driving electrodes. In this way, the chip 10 can be protected by the flexible layer 21 and the air cavity 22 , and the flexible layer 21 can be decomposed after the chip 10 is aligned with the driving electrodes on the driving backplane, so that the chip 10 can be in contact with the driving electrodes.

When the chip 10 is transferred by means of fluid self-assembly, the air cavity 22 in the above-mentioned anti-collision structure 20 can provide the chip 10 with its buoyancy in the fluid, so that the chip 10 can always keep the pad 12 facing the driving backplane direction, so as to facilitate the alignment and transfer of the control chip 10 and the driving backplane.

The air cavity 22 may be formed by the gas generated by decomposing the sacrificial layer, that is, the gas cavity 22 contains gas. Depending on the material used to form the sacrificial layer, the gas in the air cavity 22 may be different. In some embodiments, the gas includes at least one of carbon dioxide gas or ammonia gas.

The shape and size of the air cavity 22 are generally determined by the material and size of the sacrificial layer and the material of the flexible layer 21 . Sacrificial layers of different materials and sizes produce different amounts of gas when decomposed, and the sizes of the formed air cavities 22 are also different. Moreover, the shapes of the corresponding air cavities 22 formed after the sacrificial layers of different shapes are decomposed are also different. For example, air cavity 22 may be irregularly shaped or regularly shaped. Optionally, the air cavity 22 is hemispherical or semi-ellipsoidal. In this way, air cavities 22 of different shapes and sizes can be formed on different types of chips 10 when necessary, so as to differentiate the types of chips 10 according to the shapes and sizes of the air cavities 22 .

In addition, when the chip 10 is transferred by fluid self-assembly, the chip 10 needs to be suspended in the liquid. Therefore, the size of the air cavity 22 used to suspend the chip structure 100 in the liquid can be calculated in advance, and then the sacrificial layer can be reasonably selected. material and size.

Optionally, the flexible layer 21 is bonded to the surface of the epitaxial layer 11 away from the pad 12 , and the region A where the flexible layer 21 is bonded to the epitaxial layer 11 is arranged around the edge of the surface.

In the embodiment of the present application, the area A where the flexible layer 21 is bonded to the epitaxial layer 11 may be a closed area with a certain width.

In different embodiments, the shape of area A may vary.

In some embodiments, the shape of the orthographic projection of the epitaxial layer 21 on the temporary substrate is circular, the shape of the orthographic projection of the sacrificial layer on the temporary substrate is circular, and the area A where the flexible layer 21 is bonded to the epitaxial layer 11 is as shown in the figure The circular area shown in 3(a).

In some other embodiments, the shape of the orthographic projection of the epitaxial layer 21 on the temporary substrate is a rectangle, the shape of the orthographic projection of the sacrificial layer on the temporary substrate is a rectangle, and the area A where the flexible layer 21 is bonded to the epitaxial layer 11 is as shown in Figure 3 (b) The square ring region shown.

In some other embodiments, the shape of the orthographic projection of the epitaxial layer 21 on the temporary substrate is a rectangle, the shape of the orthographic projection of the sacrificial layer on the temporary substrate is a circle, and the area A where the flexible layer 21 is bonded to the epitaxial layer 11 is as shown in the figure The irregular region shown in 3(c).

In the above-mentioned chip structure 100, connecting the flexible layer 21 and the surface of the epitaxial layer 11 away from the pad 12 in an adhesive manner can make the flexible layer 21 and the epitaxial layer 11 have a better connection effect, so as to avoid the process of chip transfer. , the flexible layer 21 is separated from the epitaxial layer 11 . In addition, the bonding area A is set on the edge of the surface of the flexible layer 21 and the epitaxial layer 11 away from the pad 12, which is beneficial to make the formed air cavity 22 have a larger volume, and the flexible layer 21 can be used to protect the chip 10 easily. bumped corners to further improve the yield rate of chip transfer.

The flexible layer 21 in the embodiment of the present application has high ductility and the flexible layer 21 can be decomposed. The decomposition method of the flexible layer 21 can be selected according to actual needs, for example, thermal decomposition or photolysis can be used.

In some embodiments, the flexible layer 21 decomposes in the form of photolysis, and the flexible layer 21 includes a photodecomposition layer. The photodecomposition layer can be a polymer film with a photoinitiator added, for example: a polyimide resin film with a photoinitiator added or an unsaturated acrylic film with a photoinitiator added.

Photoinitiators, also known as photosensitizers or photocuring agents, are compounds that can absorb energy of a certain wavelength in the ultraviolet or visible light region, thereby decomposing certain chemical substances. Exemplary photoinitiators include: benzoin dimethyl ether, 2-hydroxy-2-methyl-1-phenyl-1-propanone or bis-2,6-difluoro-3-pyrrolephenyl titanocene. Among them, the value range of the absorption wavelength of benzoin dimethyl ether to light includes: 205nm～253nm, the absorption wavelength of 2-hydroxy-2-methyl-1-phenyl-1-propanone to light is 244nm, and the absorption wavelength of bis-2,6- The value range of the light absorption wavelength of difluoro-3-pyrrolephenyl titanocene includes: 333nm-470nm. It can be understood that different photoinitiators have different absorption wavelengths of light. Therefore, the photoinitiators in the embodiments of the present application can be selected in many ways to meet different requirements and applications.

In the above-mentioned chip structure 100, the flexible layer 21 can be a photodecomposition layer, and the photodecomposition layer can be a polyimide resin film added with a photoinitiator or an unsaturated acrylic film added with a photoinitiator. In this way, the properties of the photoinitiator can be used to decompose the photodecomposition layer, that is, to decompose the flexible layer 21 , and then the flexible layer 21 can be separated from the chip 10 , which facilitates the transfer of the chip 10 .

Based on the same inventive concept, the embodiment of the present application also provides a method for manufacturing a chip structure, which can simultaneously prepare multiple chip structures 100 . Please refer to Figure 4, the preparation method includes the following steps.

S110, preparing a chip on the growth substrate.

S120, transferring the chip from the growth substrate to the temporary substrate, and the epitaxial layer is located on a side of the pad away from the temporary substrate.

S130, forming a sacrificial layer covering a local area of the epitaxial layer.

S140, forming a flexible layer, the flexible layer covers the surface of the sacrificial layer and the epitaxial layer located in the peripheral area of the sacrificial layer.

S150, decomposing the sacrificial layer and generating gas; the gas makes the flexible layer protrude away from the epitaxial layer to form an air cavity.

In the above preparation method, after the chip is transferred from the growth substrate to the temporary substrate, a sacrificial layer covering a local area of the epitaxial layer may be formed on the epitaxial layer. After the sacrificial layer is formed, the flexible layer may be continuously formed so that the flexible layer covers the surface of the sacrificial layer and the epitaxial layer located in the peripheral area of the sacrificial layer. When the sacrificial layer decomposes, gas will be generated, and the gas will make the flexible layer covering the sacrificial layer bulge away from the epitaxial layer, forming an air cavity. This preparation method is relatively simple, and can improve the preparation efficiency of the chip structure, thereby improving the transfer efficiency of the chip. In addition, the embodiment of the present application uses this preparation method to prepare the chip structure in some of the aforementioned embodiments. Therefore, the technical effects that can be achieved by the chip structure in some of the aforementioned embodiments can also be achieved by this preparation method, and will not be detailed here. stated.

In S110 , as shown in FIG. 5( a ), the chip 10 is prepared on the growth substrate 30 .

The growth substrate 30 is, for example, a silicon substrate or a sapphire substrate.

The chip 10 is, for example, an LED chip. For the structure of the chip 10, reference may be made to the foregoing descriptions in some embodiments.

In S120, as shown in FIG. 5(b), the chip 10 is transferred from the growth substrate 30 to the temporary substrate 40, and the epitaxial layer 11 is located on the side of the pad 12 away from the temporary substrate 40.

The temporary substrate 40 can be selected according to actual needs, for example, a silicon substrate, a sapphire substrate or a glass substrate.

Optionally, the chip 10 and the growth substrate 30 are separated by a laser lift-off technique. The temporary substrate 40 is bonded to the pads 12 of the chip 10 .

In S130, as shown in FIG. 5(c), a sacrificial layer 50 covering a partial region of the epitaxial layer 11 is formed.

Here, the shape and size of the local area can be selected and set according to actual needs. There is a space between the boundary of the local region and the boundary of the surface of the epitaxial layer 11 facing away from the pad 12 . The local area is, for example, a circular area or a rectangular area constructed with the geometric center of the surface of the epitaxial layer 11 away from the pad 12 as the origin.

In some embodiments, step S130 includes the following steps.

S131 , as shown in FIG. 6( a ), provide a first mask M1 having a first opening H1 .

S132, as shown in FIG. 6(a), contact the first mask plate M1 with the surface of the epitaxial layer 11 away from the pad 12, and make the orthographic projection of the first opening H1 on the temporary substrate 40 be located on the epitaxial layer 11 In the orthographic projection on the temporary substrate 40 , there is a gap between the orthographic projection boundary of the first opening H1 on the temporary substrate 40 and the orthographic projection boundary of the epitaxial layer 11 on the temporary substrate 40 .

S133 , as shown in FIG. 6( b ), based on the first opening H1 , a sacrificial layer 50 is formed in a local area of the epitaxial layer 11 .

Here, the orthographic projection of the first opening H1 on the temporary base 40 coincides with the orthographic projection of the local area on the temporary base 40 .

In the above preparation method, the orthographic projection of the first opening H1 on the temporary substrate 40 is located within the orthographic projection of the epitaxial layer 11 on the temporary substrate 40, and the boundary of the orthographic projection of the first opening H1 on the temporary substrate 40 is in the same position as the epitaxial layer 11. There are spaces between the orthographic boundaries on the temporary base 40 . In this way, the shape, size and area of the sacrificial layer 50 can be limited by the shape and size of the first opening H1 in the first mask M1 and the relative position of the first opening H1 and the epitaxial layer 11 .

In S140 , as shown in FIG. 5( d ), a flexible layer 21 is formed, and the flexible layer 21 covers the sacrificial layer 50 and the surface of the epitaxial layer 11 located in the area around the sacrificial layer 50 .

Here, the surface of the epitaxial layer 11 located in the area around the sacrificial layer 50 refers to a part or all of the epitaxial layer 11 on the surface away from the pad 12 not covered by the sacrificial layer 50 . After the flexible layer 21 is formed, it can cover the sacrificial layer 50 together with the epitaxial layer 11 .

In some embodiments, step S140 includes the following steps.

S141 , as shown in FIG. 7( a ), provide a second mask M2 having a second opening H2 .

S142, as shown in FIG. 7(a), set the second mask M2 on the peripheral side of the epitaxial layer 11, so that at least the part of the epitaxial layer 11 along the thickness direction and the sacrificial layer 50 are located in the second opening H2 , and the orthographic projection of the second opening H2 on the temporary substrate 40 coincides with the orthographic projection of the epitaxial layer 11 on the temporary substrate 40 .

S143 , as shown in FIG. 7( b ), based on the second opening H2 , a flexible layer 21 is formed on the exposed surfaces of the sacrificial layer 50 and the epitaxial layer 11 .

Here, the exposed surface of the epitaxial layer 11 refers to all areas on the surface of the epitaxial layer 11 away from the pad 12 not covered by the sacrificial layer 50 .

In the embodiment of the present application, the surface of the flexible layer 21 away from the pad 12 and the surface of the second mask M2 away from the pad 12 are located in the same plane.

In the above preparation method, after the second mask M2 is sleeved on the peripheral side of the epitaxial layer 11, the part along the thickness direction of the epitaxial layer 11 and the sacrificial layer 50 are located in the second opening H2, and the second opening H2 is in the The orthographic projection on the temporary substrate 40 coincides with the orthographic projection of the epitaxial layer 11 on the temporary substrate 40 . In this way, the second opening H2 can be used to directly deposit the flexible layer 21 on the exposed surface of the sacrificial layer 50 and the epitaxial layer 11, so as to simplify the preparation process of the flexible layer 21, and it is easy to make the flexible layer 21 when the size of the sacrificial layer 50 is determined. The contact area with the epitaxial layer 11 is larger, and the flexible layer 21 can be used to protect the surface of the epitaxial layer 11 away from the pad 12 in a larger range.

In S150, as shown in FIG. 5(e), the sacrificial layer 50 is decomposed, and gas is generated; the gas makes the flexible layer 21 protrude away from the epitaxial layer 11, forming an air cavity 22.

Here, the sacrificial layer 50 is formed using a material that can decompose and generate gas.

Optionally, the gas generated after the sacrificial layer 50 is decomposed includes at least one of carbon dioxide gas or ammonia gas.

The shape and size of the air cavity 22 are generally determined by the material and size of the sacrificial layer 50 and the material of the flexible layer 21 . Sacrificial layers 50 of different materials and sizes produce different amounts of gas when decomposed, and the sizes of the formed air cavities 22 are also different. Moreover, the shapes of the corresponding air cavities 22 formed by the sacrificial layers 50 with different shapes are also different after decomposing. For example, air cavity 22 may be irregularly shaped or regularly shaped. Optionally, the air cavity 22 is hemispherical or semi-ellipsoidal. In this way, air cavities 22 of different shapes and sizes can be formed on different types of chips 10 when necessary, so as to differentiate the types of chips 10 according to the shapes and sizes of the air cavities 22 .

Optionally, both the sacrificial layer 50 and the flexible layer 21 may be formed of different materials. In this way, corresponding materials can be selected according to the decomposition methods of the sacrificial layer 50 and the flexible layer 21 .

In some embodiments, both the sacrificial layer 50 and the flexible layer 21 are decomposed by photolysis. The sacrificial layer 50 is formed by curing the first photolytic glue, and the flexible layer 21 is formed by curing the second photolytic glue. Wherein, the laser wavelengths required for the decomposition of the sacrificial layer 50 and the flexible layer 21 are different.

In the above preparation method, the sacrificial layer 50 and the flexible layer 21 are formed by curing the first photolytic glue and the second photolytic glue respectively, and the laser wavelengths required for decomposition of the sacrificial layer 50 and the flexible layer 21 are different. In this way, in the process of preparing the chip structure 100, the sacrificial layer 30 can be decomposed to generate gas by photolysis, while the flexible layer 21 is not decomposed, so that the flexible layer 21 protrudes under the action of the gas to form an air cavity 22, thereby The formation process of the air cavity 22 is simplified.

Exemplarily, the first photolytic glue is formed by polyimide resin added with photoinitiator or unsaturated acrylic acid added with photoinitiator. The second photolytic glue is formed by polyimide resin added with photoinitiator or unsaturated acrylic acid added with photoinitiator.

Wherein, when both the first photolytic glue and the second photolytic glue are formed by adding a polyimide resin with a photoinitiator, or adding an unsaturated acrylic acid with a photoinitiator, the photoinitiator in the first photolytic glue and The photoinitiators in the second photolytic glue have different absorption wavelengths of light.

In one example, the laser wavelength required for the decomposition of the first photolytic glue is greater than the laser wavelength required for the decomposition of the second photolytic glue. The first photolytic glue is, for example, polyimide resin glue with added bis-2,6-difluoro-3-pyrrole phenyl titanocene; the second photolytic glue is, for example, polyimide resin with added benzoin dimethyl ether. Amine resin glue.

In other embodiments, the sacrificial layer 50 may be formed using ammonium bicarbonate, sodium bicarbonate or dry ice.

For example, when the sacrificial layer 50 is decomposed by thermal decomposition, the sacrificial layer 50 may be formed by ammonium bicarbonate or sodium bicarbonate which is easily decomposed by thermal decomposition. In addition, the sacrificial layer 50 can be formed with dry ice at low temperature. After forming the sacrificial layer 50 with dry ice at low temperature, continue to form the flexible layer 21, and transfer the prepared structure to room temperature to turn the dry ice into carbon dioxide gas.

Based on the same inventive concept, the embodiment of the present application also provides a chip transfer method, which can transfer multiple chips 10 at the same time, please refer to FIG. 8 , the transfer method includes the following steps.

S210, transferring the chip structure into a liquid to form a chip mixed solution.

S220, providing a driving backplane, and setting an auxiliary board on a side of the driving backplane where the driving electrodes are provided; the auxiliary board includes: a chip positioning channel corresponding to the driving electrodes.

S230, injecting or draining the mixed chip solution into the chip positioning channel, and aligning and suspending the chip structure in the chip positioning channel.

S240, removing the liquid in the chip positioning channel.

S250, removing the flexible layer, making the chip drop along the chip positioning channel until the pad is aligned and in contact with the driving electrode.

In the above transfer method, the auxiliary board is located on the side of the driving backplane where the driving electrodes are provided, and the auxiliary board includes chip positioning channels corresponding to the driving electrodes. After the chip structure is transferred to the liquid forming chip mixing solution, the chip mixing solution can be injected or drained into the chip positioning channel, and the chip structure is aligned and suspended in the positioning channel. In this way, after removing the liquid and the flexible layer in the chip positioning channel, the chip can be dropped along the chip positioning channel until the pad and the driving electrode are aligned and contacted. The transfer method in the embodiment of the present application can use the auxiliary board and the chip positioning channel to accurately drop the chip to the corresponding position on the drive backplane, so as to improve the accuracy of chip transfer. In addition, before removing the flexible layer, the flexible layer and the air cavity can be used to protect the chip, so as to improve the transfer yield of the chip.

In S210 , as shown in FIG. 9( a ), the chip structure 100 is transferred into the liquid 60 to form a chip mixed solution.

The chips 10 in the embodiment of the present application include multiple types, and different types of chips 10 can be distinguished according to the light emitting colors of the chips 10 . Wherein, the luminescent color is, for example, red, green or blue. During the transfer process, chips 10 of the same color need to be placed in the same liquid 60 for transfer.

In addition, since the chip structure 100 is fixed on the temporary substrate 40 through the adhesive layer of the temporary substrate 40, when the chip structure 100 is transferred to the liquid 60, the liquid 60 needs to be used to dissolve the adhesive layer to separate the chip structure 100 and the temporary substrate. 40. Alternatively, microwave vibration may be used to separate the chip 10 from the temporary substrate 40 . After the chip structure 100 and the temporary substrate 40 are separated, the temporary substrate 40 needs to be taken out from the liquid 60 to form a chip mixing solution.

In the embodiment of the present application, the liquid 60 may be an organic solution with a lower boiling point, such as acetone, alcohol, ether, tetrahydrofuran or dichloromethane. When selecting an organic solution, attention should be paid: the selected organic solution can only dissolve the adhesive layer of the temporary base 40 , but cannot dissolve the flexible layer 21 .

In S220, as shown in Figure 9 (b), a driving backplane 70 is provided, and an auxiliary board 72 is provided on the side of the driving backplane 70 where the driving electrodes 71 are provided; the auxiliary board 72 includes: corresponding to the driving electrodes 71 The chip positioning channel 721.

There are various connection modes between the auxiliary board 72 and the driving back board 70 , for example, the auxiliary board 72 and the driving back board 70 are engaged with each other, so that the auxiliary board 72 can be removed after the transfer is completed. There are multiple chip positioning channels 721 , each chip positioning channel 721 corresponds to two driving electrodes 71 , and the two driving electrodes 71 are used to correspond to the two pads 12 of the driving chip 10 .

In the embodiment of the present application, the shape and size of the chip positioning channel 721 can be set according to different types of chips 10 . Exemplarily, the shape of the orthographic projection of the chip positioning channel 721 on the driving backplane 70 is a rectangle, but it is not limited thereto. Exemplarily, the chip positioning channel 721 extends along the thickness direction of the auxiliary board 72, and the width W (for example, the smallest dimension in the horizontal direction) of the chip positioning channel 721 at different heights may be the same, or may vary according to certain rules.

In some embodiments, the width W of the chip positioning channel 721 decreases gradually along the direction approaching the driving backplane 70 , and stops decreasing at a predetermined height away from the driving backplane 70 to form a slope S. In this way, the inclined surface S can be used to guide the chip structure 100 to quickly enter the chip positioning channel 721 . In addition, the width W of the chip positioning channel 721 is greater than the maximum dimension of one chip 10 in the horizontal direction, and smaller than the sum of the maximum dimensions of the two chips 10 in the horizontal direction. In this way, it can be ensured that only one chip 10 can pass through each chip positioning channel 721 . In the embodiment of the present application, the preset height can be determined according to the height of the chip 10 and the height of the driving electrodes 71 , for example, the preset height is the sum of the height of the chip 10 and the height of the driving electrodes 71 .

In S230 , as shown in FIG. 9( c ), the chip mixed solution is injected or drained into the chip positioning channel 721 , and the chip structure 100 is aligned and suspended in the chip positioning channel 721 .

In some embodiments, the chip mixing solution can be poured into the chip positioning channel 721 by pouring.

In S240, as shown in FIG. 9(d), the liquid 60 in the chip positioning channel 721 is removed.

Optionally, removing the liquid 60 in the chip positioning channel 721 includes: removing the liquid 60 in the chip positioning channel 721 by evaporation.

Here, the liquid 60 in the chip positioning channel 721 can be removed by heating and evaporating.

Optionally, removing the liquid 60 in the chip positioning channel 721 includes: raising the position of the driving backplane 70 along the direction close to the chip structure 100 until the driving backplane 70 is higher than the liquid level of the chip mixed solution, so that the chip is positioned The liquid 60 in the channel 721 is discharged from the side of the chip positioning channel 721 .

For example, a plurality of chip positioning channels 721 on the auxiliary board 72 are distributed in an array. And, along the row direction or the column direction where the chip positioning channels 721 are arranged, the auxiliary plate 72 is located at the bottom of the part between any two adjacent chip positioning channels 721, and the auxiliary plate 72 is located at the part between the outermost chip positioning channel 721 and the outside. The bottom of each is provided with a plurality of drain holes for communicating with the two chip positioning channels 721 . In this way, when the position of the driving backplane 70 is raised, the liquid 60 in the chip positioning channel 721 can be discharged through the liquid discharge hole.

In S250 , as shown in FIG. 9( e ), the flexible layer 21 is removed, and the chip 10 is dropped along the chip positioning channel 721 until the pad 12 is in alignment with the driving electrode 71 .

For example, different methods can be selected to remove the flexible layer 21 according to the properties of the flexible layer 21 . For example, when the flexible layer 21 is a photodecomposition layer, the flexible layer 21 can be irradiated with laser light to decompose the flexible layer 21 into gas. In this way, the chip 10 can be separated from the flexible layer 21 by laser, which is convenient for chip transfer.

It is worth mentioning that, in the embodiment of the present application, the chips 10 with different luminescent colors may share the same auxiliary board 72 during the transfer process, or use different auxiliary boards 72 for auxiliary transfer.

In some examples, chips 10 with different luminescent colors share the same auxiliary board 72 during the transfer process. Please refer to FIG. 10 , the dimensions of the plurality of chip positioning channels 721 in the auxiliary board 72 are respectively set according to the luminescent colors of the corresponding chips 10 to be transferred. For example, the plurality of chip positioning channels 721 corresponding to chips 10 of the same luminous color adopt the same size. That is, the plurality of chip positioning channels 721 in the auxiliary board 72 can be divided into chip positioning channels 721 of three different sizes for guiding red chips (R), green chips (G) and blue chips (B) respectively. ).

Correspondingly, chips 10 of the same luminous color correspond to air cavities 22 of the same size. In this way, the chip positioning channel 721 of the same size can only allow the chip structure 100 corresponding to the air cavity 22 of one size to enter. In this way, according to the size of the air cavity 22 , the chips 10 with different luminescent colors can be sequentially transferred from large to small. The transfer method can refer to the following process.

Firstly, the chip structures 100 corresponding to the chips 10 of the same luminous color are placed in the same solution 60 . Then, the chip structure 100 with the largest air cavity 22 is suspended in the chip positioning channel 721 with the largest air cavity 22, and the solution 60 and the flexible layer 21 corresponding to the chip structure 100 with the largest air cavity 22 are removed, so that the largest air cavity 22 is The pads 12 of the chip 10 are aligned and in contact with the driving electrodes 71 . Since the chip positioning channel 721 with the largest size is already occupied at this time, in the subsequent transfer process, the chip structures 100 corresponding to chips 10 of other luminescent colors will not enter the occupied chip positioning channel 721 again. Next, referring to the transfer method of the chip 10 corresponding to the air cavity 22 with the largest size, the chips 10 of other light-emitting colors can be sequentially transferred in descending order of the size of the air cavity 22 .

It should be noted that, in this embodiment, the height of the chip positioning channel 721 should not be too high, for example, the height of the chip positioning channel 721 is less than the sum of the heights of the two chips 10, which can prevent the larger chip positioning channel 721 from When already occupied, the chip structure 100 with a smaller air cavity 22 still enters by mistake.

In addition, in the example where the liquid 60 is removed by raising the position of the driving backplane 70, the cross-sectional structure of the above-mentioned auxiliary board 72 in the II' direction is shown in FIG. 11, and the auxiliary board 72 is located at any adjacent chip positioning The bottom of the part between the channels 721 and the bottom of the auxiliary plate 72 between the outermost chip positioning channel 721 and the outside are provided with a plurality of drain holes 722 . In this way, when the position of the driving backplane 70 is raised, the liquid 60 in the chip positioning channel 721 can be discharged through the connected drain hole 722 .

In some other examples, chips 10 with different luminescent colors use different auxiliary plates 72 for auxiliary transfer. In this way, the setting positions of the chip positioning channel 721 in each kind of auxiliary board 72 are different, and are specifically determined according to the position where the chip is to be transferred.

The chip 10 that needs to transfer three luminous colors is taken as an example below.

The chip 10 of the first light emitting color, such as a red chip (R), corresponds to an auxiliary board 72 as shown in FIG. 12( a ). The plurality of chip positioning channels 721 in the auxiliary board 72 are distributed according to the positions where the red light chips (R) are to be transferred.

The chip 10 of the second light emitting color, such as the green chip (G), corresponds to the auxiliary board 72 as shown in FIG. 12( b ). The multiple chip positioning channels 721 in the auxiliary board 72 are distributed according to the positions where the green chips (G) are to be transferred.

For the chip 10 of the third luminous color, for example, the blue chip (B), the corresponding auxiliary board 72 is shown in FIG. 12( c ). The plurality of chip positioning channels 721 in the auxiliary board 72 are distributed according to the positions where the Blu-ray chips (B) are to be transferred.

In this way, according to the transfer requirements of chips 10 of different luminous colors, the corresponding auxiliary board 72 can be selected and used to transfer chips 10 of any luminous color. In this way, chips 10 of different luminescent colors can be transferred independently without interfering with each other. In addition, in this embodiment, the dimensions of the chip positioning channels 721 in different auxiliary boards 72 may be the same or different, which is not limited here.

Optionally, referring to FIG. 13 , the chip transfer method further includes the following steps.

S260, removing the auxiliary board 72.

Here, the method of removing the auxiliary board 72 can be determined according to the connection mode between the auxiliary board 72 and the driving backplane 70 , for example, when the auxiliary board 72 and the driving backplane 70 are engaged with each other, the auxiliary board 72 can be removed directly.

S270 , welding the pads 12 to the corresponding driving electrodes 71 .

In the above transfer method, the auxiliary board 72 is removed and the pad 12 is soldered to the corresponding driving electrode 71 , so that the chip 10 can be connected to the driving backplane 70 to complete the chip transfer process.

The technical features of the above-mentioned embodiments can be combined arbitrarily. To make the description concise, all possible combinations of the technical features in the above-mentioned embodiments are not described. However, as long as there is no contradiction in the combination of these technical features, should be considered as within the scope of this specification.

The above-mentioned embodiments only express several implementation modes of the present application, and the description thereof is relatively specific and detailed, but should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the scope of protection of the patent application should be based on the appended claims.

Claims

A chip structure comprising:

a chip comprising an epitaxial layer and pads disposed on one side of the epitaxial layer; and

Anti-collision structure; the anti-collision structure includes: a flexible layer disposed on the side of the epitaxial layer away from the pad, and an air cavity formed by the flexible layer protruding away from the epitaxial layer.
The chip structure according to claim 1, wherein the flexible layer is bonded to the surface of the epitaxial layer away from the pad, and the bonding area of the flexible layer and the epitaxial layer is arranged around the the edge of the surface.
The chip structure as claimed in claim 2, wherein,

The shape of the air cavity includes a hemispherical shape or a semi-ellipsoidal shape.
The chip structure as claimed in claim 1, wherein,

The flexible layer includes a photodecomposition layer; the photodecomposition layer includes: a polyimide resin film added with a photoinitiator or an unsaturated acrylic film added with a photoinitiator.
The chip structure according to claim 4, wherein the photoinitiator comprises: benzoin dimethyl ether, 2-hydroxyl-2-methyl-1-phenyl-1-acetone or two 2,6-difluoro-3 - pyrrole phenyl titanocene.
The chip structure according to claim 1, wherein the gas cavity contains gas, and the gas includes at least one of carbon dioxide gas or ammonia gas.
A method for preparing a chip structure, comprising:

preparing a chip on a growth substrate, the chip comprising an epitaxial layer and a pad disposed on a side of the epitaxial layer away from the growth substrate;

transferring the chip from the growth substrate to a temporary substrate, the epitaxial layer being located on a side of the pad facing away from the temporary substrate;

forming a sacrificial layer covering a localized area of the epitaxial layer;

forming a flexible layer covering the sacrificial layer and the surface of the epitaxial layer located in the peripheral region of the sacrificial layer;

Decomposing the sacrificial layer and generating gas; the gas makes the flexible layer protrude away from the epitaxial layer to form an air cavity.
The method for preparing a chip structure according to claim 7, wherein said forming a sacrificial layer covering a local area of said epitaxial layer comprises:

providing a first reticle having a first opening;

contacting the first mask with the surface of the epitaxial layer away from the pad, and making the orthographic projection of the first opening on the temporary substrate be located on the temporary substrate of the epitaxial layer In the orthographic projection of the first opening, there is an interval between the orthographic projection boundary of the first opening on the temporary substrate and the orthographic projection boundary of the epitaxial layer on the temporary substrate;

The sacrificial layer is formed in a local area of the epitaxial layer based on the first opening.
The method for manufacturing a chip structure according to claim 8, wherein said forming a flexible layer, said flexible layer covering said sacrificial layer and the surface of said epitaxial layer located in the peripheral area of said sacrificial layer, comprises:

providing a second reticle having a second opening;

The second mask plate is sleeved on the peripheral side of the epitaxial layer, so that at least the part of the epitaxial layer along the thickness direction and the sacrificial layer are located in the second opening, and the second an orthographic projection of the opening on the temporary substrate coincides with an orthographic projection of the epitaxial layer on the temporary substrate;

Based on the second opening, the flexible layer is formed on the exposed surfaces of the sacrificial layer and the epitaxial layer.
The preparation method of chip structure as claimed in claim 7, wherein,

The sacrificial layer is formed by curing the first photolytic glue;

The flexible layer is formed by curing the second photolytic glue;

Wherein, the laser wavelengths required for the decomposition of the sacrificial layer and the flexible layer are different.
The preparation method of chip structure as claimed in claim 10, wherein,

The first photolytic glue is formed by adding a polyimide resin with a photoinitiator or an unsaturated acrylic acid with a photoinitiator;

The second photolytic glue is formed by polyimide resin added with photoinitiator or unsaturated acrylic acid added with photoinitiator;

Wherein, when both the first photolytic glue and the second photolytic glue are formed by polyimide resin with added photoinitiator, or unsaturated acrylic acid with added photoinitiator, the first photolytic glue The photoinitiator in and the photoinitiator in the second photolytic glue have different absorption wavelengths of light.
The preparation method of chip structure as claimed in claim 7, wherein,

The sacrificial layer is formed by using ammonium bicarbonate, sodium bicarbonate or dry ice.
A chip transfer method, comprising:

The chip structure is transferred into the liquid to form a chip mixed solution; wherein, the chip structure includes a chip and an anti-collision structure; the chip includes an epitaxial layer and a pad arranged on one side of the epitaxial layer; the anti-collision structure It includes: a flexible layer disposed on the side of the epitaxial layer away from the pad, and an air cavity formed by the flexible layer protruding away from the epitaxial layer;

A driving backplane is provided, and an auxiliary board is provided on the side where the driving electrodes are provided on the driving backplane; the auxiliary board includes: a chip positioning channel corresponding to the driving electrodes;

injecting or draining the chip mixed solution into the chip positioning channel, and aligning and suspending the chip structure in the chip positioning channel;

removing the liquid in the chip positioning channel;

The flexible layer is removed, and the chip is dropped along the chip positioning channel until the bonding pad is aligned and in contact with the driving electrode.
The chip transfer method according to claim 13, wherein said removing the liquid in said chip positioning channel comprises:

Evaporating and removing the liquid in the positioning channel of the chip;

Or, raise the position of the driving backplane along the direction close to the chip structure, until the driving backplane is higher than the liquid level of the chip mixed solution, so that the liquid in the chip positioning channel flows from the The side discharge of the chip positioning channel.
The chip transfer method according to claim 13, wherein said flexible layer comprises a photodecomposition layer; said removing said flexible layer comprises:

Laser light irradiates the flexible layer to decompose the flexible layer into gas.
The chip transfer method according to any one of claims 13-15, wherein the chip transfer method further comprises:

removing the auxiliary plate;

Welding the pads to the corresponding driving electrodes.