Chip transfer method and display panel

Abstract

The present application relates to the display field, and specifically discloses a chip transfer method and a display panel. The chip transfer method includes the following steps: providing a first substrate and a second substrate; preparing an epitaxial layer on the first substrate, and cutting the epitaxial layer to form a plurality of chips; forming a photoresist layer between two adjacent chips, and opening an opening at a position of the photoresist layer in contact with the chip; preparing electrodes on the chip, and connecting the chip to the second substrate through the electrodes; performing a laser stripping operation on the side of the epitaxial layer close to the first substrate to strip the epitaxial layer from the first substrate; and removing the photoresist layer to separate the chip from the first substrate. The present application improves the problem of the chip being tilted or blown away by the nitrogen generated during stripping by the above method.

Description

Technical Field

[0001] The present application relates to the display field, and in particular to a chip transfer method and a display panel. Background Art

[0002] In the preparation of Micro-LEDs (micrometer light-emitting diodes), when using the laser lift-off method to separate the chip from the growth substrate, the laser acts on the interface between the chip and the substrate to decompose the epitaxial gallium nitride into gallium and nitrogen. At this time, due to the small size and light weight of the micro LED, the large amount of nitrogen generated instantly will blow the micro-LED tilted or even directly blow it, causing chip damage and transfer failure.

[0003] Therefore, how to improve the chip from being affected by nitrogen gas generated during peeling, causing it to tilt or be blown away, has become an urgent problem to be solved in this field. Summary of the Invention

[0004] The present application discloses a chip transfer method and a display panel, the purpose of which is to improve the problem that the chip is affected by nitrogen gas generated during peeling and is tilted or blown away.

[0005] The present application discloses a chip transfer method, comprising the steps of:

[0006] Providing a first substrate and a second substrate;

[0007] preparing an epitaxial layer on the first substrate, and cutting the epitaxial layer to form a plurality of chips;

[0008] forming a photoresist layer between two adjacent chips, and providing an opening at a position of the photoresist layer in contact with the chip;

[0009] preparing electrodes on the chip, and connecting the chip to the second substrate via the electrodes;

[0010] performing a laser lift-off operation on a side of the epitaxial layer close to the first substrate to lift the epitaxial layer off from the first substrate;

[0011] The photoresist layer is removed to separate the chip from the first substrate.

[0012] Optionally, the step of preparing an epitaxial layer on the first substrate and cutting the epitaxial layer to form a plurality of chips includes:

[0013] forming a U-type gallium nitride layer, an N-type gallium nitride layer, a multi-quantum well layer, and a P-type gallium nitride layer in sequence on the first substrate to form the epitaxial layer;

[0014] performing a laser etching operation on the back surface of the U-shaped gallium nitride layer to form a plurality of channels;

[0015] In the step of forming a photoresist layer between two adjacent chips and opening holes at positions of the photoresist layer in contact with the chips, a photoresist layer is formed in the plurality of channels and between two adjacent chips to fix the chips, and opening holes are opened at positions of the photoresist layer in contact with the chips;

[0016] In the step of performing a laser lift-off operation on a side of the epitaxial layer close to the first substrate to lift the epitaxial layer off the first substrate, lift-off laser irradiation is performed on the back surface of the U-shaped gallium nitride layer to lift the U-shaped gallium nitride layer off the first substrate, thereby lifting the epitaxial layer off the first substrate;

[0017] In the step of removing the photoresist layer to separate the chip from the first substrate, the photoresist layer under the chip is removed to separate the chip from the first substrate.

[0018] Optionally, the multiple channels are located below the chip, and the multiple channels are in a cross shape or a well shape, and each channel has openings at both ends.

[0019] Optionally, at least two channels arranged at intervals are formed below each chip.

[0020] Optionally, the width of each channel is greater than or equal to one third of the width of the epitaxial layer and less than one half of the width of the epitaxial layer.

[0021] Optionally, the step of forming a photoresist layer in the plurality of channels and between two adjacent chips to fix the chips, and opening holes at positions of the photoresist layer in contact with the chips includes:

[0022] Filling photoresist material in the plurality of channels and between two adjacent chips;

[0023] performing a first heating and curing on the photoresist material to form a photoresist layer;

[0024] By exposure and development, the opening is formed in the photoresist layer between two adjacent chips and in the portion contacting the chip;

[0025] performing a second heating and curing on the photoresist layer;

[0026] Wherein, the temperature of the second heating and curing is higher than the temperature of the first heating and curing.

[0027] Optionally, the step of preparing electrodes on the chip and connecting the chip to the second substrate via the electrodes includes:

[0028] removing a portion of the multi-quantum well layer and the P-type gallium nitride layer above the N-type gallium nitride layer to expose a portion of the N-type gallium nitride layer, thereby forming a stepped chip;

[0029] preparing a first electrode and a second electrode, wherein the first electrode is connected to the P-type gallium nitride layer; and the second electrode is connected to the N-type gallium nitride layer;

[0030] The length of the first electrode is smaller than the length of the second electrode.

[0031] Optionally, the step of performing a lift-off laser irradiation on the back surface of the U-shaped gallium nitride layer to lift the U-shaped gallium nitride layer off the first substrate includes:

[0032] The back surface of the U-shaped gallium nitride layer is irradiated with laser for a first preset time to remove the U-shaped gallium nitride portion on the same layer as the photoresist under the chip.

[0033] Optionally, the step of performing a lift-off laser irradiation on the back surface of the U-shaped gallium nitride layer to lift the U-shaped gallium nitride layer off the first substrate includes:

[0034] The back surface of the U-shaped gallium nitride layer is irradiated with laser light for a second preset time to completely remove the U-shaped gallium nitride layer.

[0035] An embodiment of the present application further discloses a display panel, which includes a second substrate and a plurality of chips. The plurality of chips are connected to the second substrate through the above-mentioned chip transfer method.

[0036] The present application improves upon the conventional chip transfer method. First, an epitaxial layer is formed on a first substrate, and then the epitaxial layer is cut into a plurality of desired chips. A photoresist layer is formed between two adjacent chips, so that the photoresist layer fills the gap between the two adjacent chips and each chip is wrapped from the side by the photoresist layer. This allows the chip to be effectively fixed by the photoresist layer, thereby improving the stability of the chip. Then, an opening is formed in the photoresist layer at a position in contact with the chip, so that gas generated when decomposing the portion where the epitaxial layer is connected to the first substrate can flow out through the opening to the external environment without accumulating at the bottom of the chip, causing increased gas pressure to blow the chip or damage the chip. Thus, after the chip is connected to the second substrate via electrodes, a laser lift-off operation is performed on the portion where the epitaxial layer is connected to the first substrate. After the epitaxial layer is separated from the first substrate, the photoresist layer can still limit and fix the chip from the side to a certain extent. Finally, the photoresist layer is removed to completely separate the chip from the first substrate, ultimately completing the chip transfer. This effectively alleviates the problem of the chip being tilted or blown away by the gas generated during lift-off during the chip transfer process, thereby improving production reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The included drawings are used to provide a further understanding of the embodiments of the present application, which constitute a part of the specification, are used to illustrate the implementation methods of the present application, and together with the text description, explain the principles of the present application. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without inventive work. In the drawings:

[0038] Figure 1 This is a step diagram of the first embodiment of the chip transfer method of the present application;

[0039] Figure 2 This is a step diagram of a second embodiment of the chip transfer method of the present application;

[0040] Figure 3 This is a diagram of the steps of forming multiple channels on the back surface of the U-shaped gallium nitride layer in the second embodiment of the chip transfer method of the present application;

[0041] Figure 4 This is a diagram showing the steps of forming a photoresist layer and opening a hole in the photoresist layer at a position in contact with the chip in the second embodiment of the chip transfer method of the present application;

[0042] Figure 5 This is a diagram of the steps for preparing electrodes on a chip in the second embodiment of the chip transfer method of the present application;

[0043] Figure 6This is a diagram showing the steps of peeling off the U-shaped gallium nitride layer in the second embodiment of the chip transfer method of the present application;

[0044] Figure 7 This is a schematic diagram of fabricating an epitaxial layer in the second embodiment of the chip transfer method of the present application;

[0045] Figure 8 This is a schematic diagram of a channel fabrication method according to a second embodiment of the chip transfer method of the present application;

[0046] Figure 9 A partial top view of a channel fabricated in the second embodiment of the chip transfer method of the present application;

[0047] Figure 10 This is a schematic diagram of chip fabrication in the second embodiment of the chip transfer method of the present application;

[0048] Figure 11 This is a partial top view of a second embodiment of the chip transfer method of the present application, showing an opening formed in a photoresist layer;

[0049] Figure 12 This is a cross-sectional view of a second embodiment of the chip transfer method of the present application, showing an opening formed in the photoresist layer;

[0050] Figure 13 This is a schematic diagram of fabricating electrodes on a chip in the second embodiment of the chip transfer method of the present application;

[0051] Figure 14 This is a schematic diagram of removing the U-shaped gallium nitride layer in the second embodiment of the chip transfer method of the present application;

[0052] Figure 15 This is a schematic diagram of removing the photoresist layer in the second embodiment of the chip transfer method of the present application;

[0053] Figure 16 This is a diagram showing the steps of removing the U-shaped gallium nitride layer in the third embodiment of the chip transfer method of the present application;

[0054] Figure 17 FIG. 1 is a schematic diagram of an embodiment of a display panel of the present application.

[0055] Among them, 10, display panel; 100, first substrate; 200, second substrate; 110, epitaxial layer; 111, U-shaped gallium nitride layer; 112, channel; 113, opening; 114, first side; 115, second side; 120, N-type gallium nitride layer; 130, multi-quantum well layer; 140, P-type gallium nitride layer; 150, photoresist layer; 151, opening; 160, electrode; 161, first electrode; 162, second electrode; 170, chip. DETAILED DESCRIPTION

[0056] The present application is described in detail below with reference to the accompanying drawings and optional embodiments. It should be noted that, under the premise of no conflict, the embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0057] Figure 1 This is a step diagram of the first embodiment of the chip transfer method of this application, as shown in FIG. Figure 1 As shown,

[0058] This application discloses a chip 170 transfer method, comprising the steps of:

[0059] S1: providing a first substrate 100 and a second substrate 200;

[0060] S2: preparing an epitaxial layer 110 on the first substrate 100, and cutting the epitaxial layer 110 to form a plurality of chips 170;

[0061] S3: forming a photoresist layer 150 between two adjacent chips 170 and opening 151 at a position of the photoresist layer 150 in contact with the chip 170;

[0062] S4: preparing an electrode 160 on the chip 170, and connecting the chip 170 to the second substrate 200 through the electrode 160;

[0063] S5: performing a laser lift-off operation on a side of the epitaxial layer 110 close to the first substrate 100 to lift the epitaxial layer 110 off the first substrate 100;

[0064] S6: removing the photoresist layer 150 to separate the chip 170 from the first substrate 100.

[0065] The present application improves the traditional chip transfer method. First, an epitaxial layer 110 is formed on a first substrate 100, and then the epitaxial layer 110 is cut into a plurality of required chips 170. A photoresist layer 150 is formed between two adjacent chips 170, so that the photoresist layer 150 fills the gap between the two adjacent chips 170, and each chip 170 is wrapped from the side by the photoresist layer 150. In this way, the chip can be effectively fixed by the photoresist layer 150, thereby improving the stability of the chip 170. Then, an opening 151 is opened at the position of the photoresist layer 150 in contact with the chip 170, so that the gas generated when the connection portion between the epitaxial layer 110 and the first substrate 100 is decomposed can flow out to the external environment through the opening 151 without being trapped in the chip 170. The accumulation at the bottom of 70 causes the air pressure to increase and blow the chip 170 or damage the chip 170; in this way, after the chip 170 is connected to the second substrate 200 through the electrode 160, the portion where the epitaxial layer 110 is connected to the first substrate 100 can be laser stripped, so that after the epitaxial layer 110 is separated from the first substrate 100, the photoresist layer 150 can still limit and fix the chip 170 from the side to a certain extent; finally, the photoresist layer 150 is removed to completely separate the chip 170 from the first substrate 100, and the transfer of the chip 170 is finally completed. In this way, the problem that the chip 170 is affected by the gas generated during the stripping during the transfer process of the chip 170, causing it to tilt or be blown away, can be effectively improved, thereby improving production reliability.

[0066] It should be noted that the chip in this application refers to an LED chip, and the first substrate 100 can be a growth substrate, among which a sapphire substrate is one of the currently commonly used Micro LED epitaxial growth substrates. Micro LED chips are usually grown on a sapphire substrate using metal organic chemical vapor deposition (MOCVD) or metal organic vapor phase epitaxy (MOVPE) technology; of course, there are other types of growth substrates, and this application only uses a sapphire substrate as an example of the first substrate 100; the second substrate 200 can be the backplane of the display panel 10, that is, the chip 170 is directly transferred to the final product. The second substrate 200 can also be a temporary substrate used for a transfer process during the preparation of the display panel 10. Multiple chips 170 are first connected to the temporary substrate, and then the density of the multiple chips 170 on the temporary substrate is adjusted according to actual product requirements. After the adjustment is completed, the chips 170 on the temporary substrate are transferred to the backplane of the display panel 10.

[0067] Figure 2 This is a step diagram of a second embodiment of the chip transfer method of the present application; Figure 3 This is a diagram of the steps of forming multiple channels on the back surface of the U-shaped gallium nitride layer in the second embodiment of the chip transfer method of the present application; Figure 4This is a diagram showing the steps of forming a photoresist layer and opening a hole in the photoresist layer at a position in contact with the chip in the second embodiment of the chip transfer method of the present application; Figure 5 This is a diagram of the steps for preparing electrodes on a chip in the second embodiment of the chip transfer method of the present application; Figure 6 This is a diagram showing the steps of peeling off the U-shaped gallium nitride layer in the second embodiment of the chip transfer method of the present application;

[0068] Figure 7 This is a schematic diagram of fabricating an epitaxial layer in the second embodiment of the chip transfer method of the present application; Figure 8 This is a schematic diagram of a channel fabrication method according to a second embodiment of the chip transfer method of the present application; Figure 9 A partial top view of a channel fabricated in the second embodiment of the chip transfer method of the present application; Figure 10 This is a schematic diagram of chip fabrication in the second embodiment of the chip transfer method of the present application; Figure 11 This is a partial top view of a second embodiment of the chip transfer method of the present application, showing an opening formed in a photoresist layer; Figure 12 This is a cross-sectional view of a second embodiment of the chip transfer method of the present application, showing an opening formed in the photoresist layer; Figure 13 This is a schematic diagram of fabricating electrodes on a chip in the second embodiment of the chip transfer method of the present application; Figure 14 This is a schematic diagram of removing the U-shaped gallium nitride layer in the second embodiment of the chip transfer method of the present application; Figure 15 Schematic diagram of removing the photoresist layer in the second embodiment of the chip transfer method of the present application; Figures 2 to 15 As shown,

[0069] The embodiment of the present application discloses a chip 170 transfer method, comprising the steps of:

[0070] S2: The steps of preparing an epitaxial layer 110 on the first substrate 100 and cutting the epitaxial layer 110 to form a plurality of chips 170 include:

[0071] S21: forming a U-type gallium nitride layer 111, an N-type gallium nitride layer 120, a multi-quantum well layer 130, and a P-type gallium nitride layer 140 on the first substrate 100 in sequence to form an epitaxial layer 110;

[0072] S22: performing a laser etching operation on the back surface of the U-shaped gallium nitride layer 111 to form a plurality of channels 112;

[0073] S3: forming a photoresist layer 150 between two adjacent chips 170 and opening an opening 151 at a position of the photoresist layer 150 in contact with the chip 170, S31: forming a photoresist layer 150 in the plurality of channels 112 and between two adjacent chips 170 to fix the chip 170, and opening 151 at a position of the photoresist layer 150 in contact with the chip 170;

[0074] S5: performing a laser lift-off operation on a side of the epitaxial layer 110 close to the first substrate 100 to lift the epitaxial layer 110 off the first substrate 100, S51: irradiating a lift-off laser on the back side of the U-shaped gallium nitride layer 111 to lift the U-shaped gallium nitride layer 111 off the first substrate 100, thereby lifting the epitaxial layer 110 off the first substrate 100;

[0075] In the step of removing the photoresist layer 150 to separate the chip 170 from the first substrate 100 , S61 : removing the photoresist layer 150 under the chip 170 to separate the chip 170 from the first substrate 100 .

[0076] This embodiment differs from the previous embodiment in that, in this embodiment, in the formed epitaxial layer 110, a plurality of channels 112 are formed in the bottommost U-shaped gallium nitride layer 111 by laser etching, and the etched channels 112 and the gaps between two adjacent chips 170 are filled by the photoresist layer 150. Then, the U-shaped gallium nitride layer 111 is peeled off from the first substrate 100 by a laser lift-off operation. Finally, the photoresist layer 150 under the chip 170 is removed, so that the chip 170 is completely separated from the first substrate 100.

[0077] For ease of understanding, the specific steps of this embodiment are:

[0078] S1: providing a first substrate 100 and a second substrate 200;

[0079] S21: forming a U-type gallium nitride layer 111, an N-type gallium nitride layer 120, a multi-quantum well layer 130, and a P-type gallium nitride layer 140 on the first substrate 100 in sequence to form an epitaxial layer 110;

[0080] S22: performing a laser etching operation on the back surface of the U-shaped gallium nitride layer 111 to form a plurality of channels 112;

[0081] S23: cutting the epitaxial layer 110 to form a plurality of chips 170;

[0082] S31: forming a photoresist layer 150 in the plurality of channels 112 and between two adjacent chips 170, and openings 151 at positions of the photoresist layer 150 in contact with the chips 170;

[0083] S4: preparing an electrode 160 on the chip 170, and connecting the chip 170 to the second substrate 200 through the electrode 160;

[0084] S51: performing a laser lift-off operation on the back surface of the U-shaped gallium nitride layer 111 to lift the U-shaped gallium nitride layer 111 off the first substrate 100;

[0085] S61: removing the photoresist layer 150 under the chip 170 to separate the chip 170 from the first substrate 100.

[0086] In this embodiment, a U-shaped gallium nitride layer 111, an N-type gallium nitride layer 120, a multi-quantum well layer 130, and a P-type gallium nitride layer 140 are sequentially formed on a first substrate 100, thereby forming an epitaxial layer 110 on the first substrate 100; then, a laser etching operation is performed on the back side of the U-shaped gallium nitride layer 111. As the laser is irradiated, the laser-irradiated portion of the U-shaped gallium nitride layer 111 is decomposed into gallium and nitrogen. The laser irradiation forms a plurality of channels 112 on the back side of the U-shaped gallium nitride layer 111. These channels 112 form gaps between the first substrate 100, thereby decomposing the U-shaped gallium nitride layer 111. The gas generated by the U-shaped gallium nitride layer 111 can be released from the channel 112; while the remaining U-shaped gallium nitride layer 111 is still connected to the first substrate 100, and because the epitaxial layer 110 has not yet been divided into small parts and has a large mass, it will not be blown by the generated nitrogen; then the epitaxial layer 110 is divided into the required chip 170 size. At this time, there are gaps between two adjacent chips 170 and in the channel 112. A photoresist layer 150 is formed in the multiple channels 112 and in the gaps between two adjacent chips 170, so that the photoresist layer 150 is The channel 112 and the gap between two adjacent chips 170 are filled, so that the chip 170 can be effectively fixed by the photoresist layer 150, thereby improving the stability of the chip 170; then, an opening 151 is opened at the position of the photoresist layer 150 in contact with the chip 170, so that the nitrogen generated when the U-shaped gallium nitride layer 111 is decomposed can flow out to the external environment through the opening 151, without forming an accumulation at the bottom of the chip 170, causing the gas pressure to increase and blow the chip 170 or damage the chip 170; after the electrode 160 is prepared on the chip 170, the back of the U-shaped gallium nitride layer 111 is laser-treated. The U-shaped gallium nitride layer 111 is peeled off from the first substrate 100 by a peeling operation, so that only the photoresist layer 150 remains below the chip 170 connected to the first substrate 100. In this way, after the chip 170 is connected to the second substrate 200 via the electrode 160, the photoresist layer 150 below the chip 170 is removed to separate the chip 170 from the first substrate 100, and finally complete the transfer of the chip 170. This can effectively alleviate the problem of the chip 170 being affected by the nitrogen generated during the peeling process during the transfer process, causing the chip 170 to tilt or be blown away, thereby improving production reliability.

[0087] Specifically, S22: performing a laser etching operation on the back surface of the U-shaped gallium nitride layer 111 to form a plurality of channels 112 includes:

[0088] S221 : The laser moves along the first side 114 of the U-shaped GaN layer 111 to the second side 115 of the U-shaped GaN layer 111 ; or the laser moves along the first side 114 and the second side 115 of the U-shaped GaN layer 111 toward the middle of the epitaxial layer 110 .

[0089] After the epitaxial layer 110 is prepared by MOCVD or other methods, a laser is first used to irradiate the U-shaped gallium nitride layer 111 on the side close to the growth substrate to remove a portion of the U-shaped gallium nitride layer 111. The laser is then moved from one edge of the U-shaped gallium nitride layer 111 to the other edge of the U-shaped gallium nitride layer 111, or from both edges of the U-shaped gallium nitride layer 111 toward the center. As the laser moves, the U-shaped gallium nitride layer 111 decomposes, forming a channel 112 on the side of the U-shaped gallium nitride layer 111 close to the first substrate 100. As the laser continues to move, the gas generated by the decomposition of the U-shaped gallium nitride layer 111 can be released through the channel 112. In this way, the nitrogen gas generated as the laser moves will not accumulate at the bottom of the chip 170, causing damage to the chip 170.

[0090] At the same time, since the laser only decomposes part of the U-shaped gallium nitride layer 111 at this time, most of the remaining U-shaped gallium nitride layer 111 is still connected to the growth substrate, and the entire epitaxial layer 110 has not yet been divided into very small parts and has a large mass. Under the dual influence of the large contact area between the U-shaped gallium nitride and the growth substrate and the gravity of the epitaxial layer 110 itself, the entire epitaxial layer 110 will not be blown by the nitrogen, thereby ensuring the stability of the epitaxial layer 110.

[0091] Furthermore, to ensure that the nitrogen generated during laser irradiation of the U-shaped gallium nitride layer 111 can be quickly released from the channel 112 and to provide a structural foundation for forming a stable connection between the photoresist and the chip 170 in subsequent steps, the present application also improves the structure of the channel 112. The specific improvements are as follows:

[0092] The multiple channels 112 are formed below the chip 170 and are arranged in a cross or a cross shape. Each channel 112 has an opening 113 at both ends. Because the cross or cross-shaped channels 112 can connect to each side of the U-shaped gallium nitride layer 111, when gas is generated, it will be released from the openings 113 of the channels 112 along the direction of the channels 112 toward each side of the U-shaped gallium nitride layer 111. This helps disperse the gas release, accelerates the gas release rate, and alleviates the gas sweep pressure on the chip 170, thereby improving the chip 170 from skewing or damage caused by the gas during the transfer process.

[0093] In addition, the cross-shaped or well-shaped channel 112 provides a structural basis for filling photoresist in subsequent processes. When the photoresist in the subsequent process is filled into the channel 112, a cross-shaped or well-shaped shape will also be formed. This can ensure that the photoresist in the channel 112 has sufficient area to connect with the chip 170, thereby preventing the chip 170 from positionally shifting during the transfer process, thereby enhancing the stability of the connection between the photoresist and the chip 170; and the formed cross-shaped or well-shaped photoresist can provide better support for the chip 170, so that the chip 170 remains level during the entire transfer process, which is beneficial to improving the accuracy and efficiency of the transfer of the chip 170.

[0094] Similarly, considering that a photoresist needs to be filled in the channel 112 in subsequent processes, the photoresist can fix the chip 170 while supporting the chip 170 in a horizontal state, thereby facilitating rapid and accurate installation on the second substrate 200; the present application further improves the channel 112 as follows:

[0095] At least two spaced-apart channels 112 are formed below each chip 170. On the one hand, the two spaced-apart channels 112 form dual channels 112 in the same direction below the chip 170, accelerating the gas flow rate and allowing the generated gas to be quickly released through the channels 112, thereby reducing gas damage to the chip 170. On the other hand, the side-by-side channels 112 provide a structural foundation for the subsequent filling of photoresist to stably support the chip 170. After the photoresist is filled in the subsequent process, the photoresist forms a side-by-side photoresist layer 150 within the channels 112, providing support on both sides below the chip 170. This helps keep the chip 170 level, thereby facilitating quick and accurate installation on the second substrate 200 and improving transfer efficiency and stability.

[0096] In addition, the width of each channel 112 is greater than or equal to one-third of the width of the epitaxial layer 110 and less than one-half of the width of the epitaxial layer 110. This prevents the width of each channel 112 from being too narrow. When nitrogen flows through the channel 112, a large amount of nitrogen can be released from the channel 112 while maintaining its flow rate, thereby preventing nitrogen from accumulating at the bottom of the chip 170 and damaging the chip 170.

[0097] When the photoresist is filled in the subsequent process, since the photoresist will be filled into the channel 112, the width of the channel 112 determines the width of the photoresist in the channel 112. This ensures that the photoresist in the channel 112 has enough area to connect with the chip 170, thereby preventing the chip 170 from being positionally shifted during the transfer process, thereby enhancing the stability of the connection between the photoresist and the chip 170.

[0098] Furthermore, S31: forming a photoresist layer 150 in the plurality of channels 112 and between two adjacent chips 170, and opening holes 151 at positions of the photoresist layer 150 in contact with the chips 170 includes:

[0099] S311: Filling photoresist material in the plurality of channels 112 and between two adjacent chips 170;

[0100] S312: performing a first heating and curing on the photoresist material to form a photoresist layer 150;

[0101] S313: forming an opening 151 in the photoresist layer 150 between two adjacent chips 170 and in the portion contacting the chip 170 by exposure and development;

[0102] S314: performing a second heating and curing on the photoresist layer 150; wherein the temperature of the second heating and curing is higher than the temperature of the first heating and curing.

[0103] In the process of making the photoresist layer 150 of the present application, the photoresist material is first filled into the multiple channels 112 and between two adjacent chips 170. Since the initial state of the photoresist material is liquid and has fluidity, the photoresist material will be filled into the channels 112 and the gap between two adjacent chips 170.

[0104] After filling, the photoresist material is heated and cured for the first time. The heating temperature is generally between 80 degrees Celsius and 100 degrees Celsius, so that the photoresist material is pre-cured to form a photoresist layer 150. At this time, the photoresist layer 150 forms a relatively solid shape.

[0105] Then, through exposure and development, an opening 151 is formed in the photoresist layer 150 between two adjacent chips 170 and the portion contacting the chip 170, so that the gas generated by the decomposition of the U-shaped gallium nitride layer 111 after being irradiated by laser in subsequent processes can be released into the external environment through the opening 151.

[0106] After the opening 151 is completed, the photoresist layer 150 is heated and cured for a second time. The temperature range of the second heating and curing can be between 180 degrees Celsius and 200 degrees Celsius. The second heating and curing completely cures the photoresist layer 150, so that the photoresist layer 150 can be used to fix the chip 170. Therefore, the chip 170 is not solely connected to the growth substrate by relying on the U-shaped gallium nitride layer 111. This improves the stability of the chip 170 connection and makes it less likely that the chip 170 will be distorted or damaged by the nitrogen generated during the transfer process, thereby improving the production yield.

[0107] After the photoresist is cured, an electrode 160 may be formed on the chip 170 to connect the chip 170 to the second substrate 200. In this application, S4: forming the electrode 160 on the chip 170 and connecting the chip 170 to the second substrate 200 via the electrode 160 includes:

[0108] S41: Excluding the portion of the multi-quantum well layer 130 and the P-type GaN layer 140 above the N-type GaN layer 120 to expose a portion of the N-type GaN layer 120 , thereby forming a stepped chip 170 ;

[0109] S42: Prepare a first electrode 161 and a second electrode 162, wherein the first electrode 161 is connected to the P-type gallium nitride layer 140; the second electrode 162 is connected to the N-type gallium nitride layer 120; wherein the length of the first electrode 161 is smaller than the length of the second electrode 162.

[0110] During the process of preparing the electrode 160 on the chip 170 , it is first necessary to remove a portion of the multi-quantum well layer 130 and the P-type gallium nitride layer 140 above the N-type gallium nitride layer 120 , thereby exposing a portion of the N-type gallium nitride layer 120 for connection to the second electrode 162 .

[0111] Since there is a step-like gap between the portion of the N-type gallium nitride layer 120 connected to the second electrode 162 and the other portions of the chip 170, the length of the prepared second electrode 162 is greater than that of the first electrode 161, so that the second electrode 162 can be stably connected to the N-type gallium nitride layer 120. The first electrode 161 is connected to the P-type gallium nitride layer 140, and the second electrode 162 is connected to the N-type gallium nitride layer 120, so that the first electrode 161 and the second electrode 162 are respectively connected to the positive and negative poles of the chip 170; then, the chip 170 is connected to the second substrate 200 through the electrode 160.

[0112] Furthermore, S51: performing a laser lift-off operation on the back surface of the U-shaped gallium nitride layer 111 to lift the U-shaped gallium nitride layer 111 off the first substrate 100 includes:

[0113] S511 : performing laser irradiation on the back surface of the U-shaped GaN layer 111 for a first predetermined time to remove the U-shaped GaN portion on the same layer as the photoresist layer below the chip 170 .

[0114] After the first substrate 100 (growth substrate) and the second substrate 200 (temporary substrate or backplane) are aligned, the chip 170 needs to be peeled off from the growth substrate so that the chip 170 remains on the second substrate 200, thereby completing the transfer of the chip 170.

[0115] The back side of the U-shaped gallium nitride layer 111 below the chip 170 is laser irradiated for a first preset time. By controlling the laser irradiation time, the laser only removes the U-shaped gallium nitride portion on the same layer as the photoresist below the chip 170, so that only the photoresist below the chip 170 is connected to the growth substrate. This can shorten the laser irradiation time, thereby controlling production costs.

[0116] Finally, the photoresist under the chip 170 is washed away by a photoresist stripping liquid, thereby completing the stripping of the chip 170 from the growth substrate and transferring the chip 170 to a temporary substrate or backplane. This completes the transfer of the chip 170 and can improve the problem that the chip 170 is affected by the nitrogen generated during the stripping process during the transfer of the chip 170, causing it to tilt or be blown away, thereby improving production reliability.

[0117] Figure 16 FIG. 1 is a diagram showing the steps of removing the U-shaped gallium nitride layer in the third embodiment of the chip transfer method of the present application; Figure 15 As shown,

[0118] S51: performing a laser lift-off operation on the back surface of the U-shaped gallium nitride layer 111 to lift the U-shaped gallium nitride layer 111 off the first substrate 100 includes:

[0119] S521 : performing laser irradiation on the back surface of the U-shaped GaN layer 111 for a second predetermined time to completely remove the U-shaped GaN layer 111 .

[0120] This embodiment differs from the previous embodiment in that, after the electrode 160 on the chip 170 is prepared, the back of the U-shaped gallium nitride layer 111 is irradiated with a laser. By controlling the laser irradiation time, wherein the second preset time is longer than the first preset time, the U-shaped gallium nitride layer 111 is completely removed by extending the laser irradiation time. This helps to reduce the overall thickness of the chip 170, thereby achieving a thinner chip 170, and further helps to achieve a thinner display panel 10.

[0121] Figure 17 This is a schematic diagram of an embodiment of the display panel of the present application. Figure 16 As shown, the embodiment of the present application further discloses a display panel 10, which includes a second substrate 200 and a plurality of chips 170. The plurality of chips 170 are connected to the second substrate 200 using the aforementioned chip 170 transfer method. Mounting the plurality of chips 170 on the second substrate 200 using the chip 170 transfer method can, on the one hand, increase the speed of chip 170 installation and accelerate the production efficiency of the display panel 10, and on the other hand, can be used for normal light emission of the display panel 10; wherein, the second substrate 200 can be the backplane of the display panel 10.

[0122] The display panel 10 in this application is mainly for a Micro LED (micro light emitting diode) display panel 10, which has a high-density integrated LED array. The distance between the LED chips 170 in the array is generally in the micron level, and each LED chip 170 can emit light by itself.

[0123] When a conventional Micro LED display panel 10 uses a chip 170 transfer method to transfer multiple chips 170 to a backplane of the display panel 10 , the chips 170 are easily damaged or skewed, thereby affecting the yield of the display panel 10 .

[0124] Based on the above problems, the present application improves the method for transferring the chip 170 of the display panel 10. First, a U-shaped gallium nitride layer 111, an N-type gallium nitride layer 120, a multi-quantum well layer 130, and a P-type gallium nitride layer 140 are sequentially formed on the first substrate 100, thereby forming an epitaxial layer 110 on the first substrate 100; then, a laser etching operation is performed on the back side of the U-shaped gallium nitride layer 111. As the laser is irradiated, the portion of the U-shaped gallium nitride layer 111 irradiated by the laser decomposes into gallium and nitrogen. The laser irradiation is used to form a plurality of channels 112 on the back side of the U-shaped gallium nitride layer 111. These channels 112 are formed on the first substrate 1 00, so that the gas generated by decomposing the U-shaped gallium nitride layer 111 can be released from the channel 112; while the remaining U-shaped gallium nitride layer 111 is still connected to the first substrate 100, and because the epitaxial layer 110 has not yet been divided into small parts at this time, the mass is large and therefore will not be blown by the generated nitrogen; then the epitaxial layer 110 is divided into the required chip 170 size. At this time, there are gaps between adjacent chips 170 and in the channel 112, and a photoresist layer 150 is formed in the multiple channels 112 and between adjacent chips 170, so that the photoresist layer 150 is not conducive to the passage. The gaps between the channel 112 and the adjacent chips 170 are filled, so that the chip 170 can be effectively fixed by the photoresist layer 150, thereby improving the stability of the chip 170; then, an opening 151 is opened at the position of the photoresist layer 150 in contact with the chip 170, so that the nitrogen generated when the U-shaped gallium nitride layer 111 is decomposed can flow out to the external environment through the opening 151, without forming an accumulation at the bottom of the chip 170, causing the gas pressure to increase and blow the chip 170 or damage the chip 170; after the electrode 160 is prepared on the chip 170, the back of the U-shaped gallium nitride layer 111 is subjected to a laser lift-off operation to remove the U-shaped gallium nitride layer. 111 is peeled off from the first substrate 100, so that only the photoresist layer 150 is left under the chip 170 connected to the first substrate 100; in this way, after the chip 170 is connected to the second substrate 200 through the electrode 160, the photoresist layer 150 under the chip 170 is removed to separate the chip 170 from the first substrate 100, and finally the transfer of the chip 170 is completed. In this way, the problem of the chip 170 being affected by the nitrogen generated during the peeling during the transfer process of the chip 170, causing the chip 170 to be tilted or blown away, can be effectively improved, thereby improving production reliability; and thereby improving the yield rate of the display panel 10 and the quality of the display panel 10.

[0125] It should be noted that the inventive concept of this application can form a large number of embodiments, but the length of the application document is limited and it is impossible to list them one by one. Therefore, under the premise of no conflict, the various embodiments or technical features described above can be arbitrarily combined to form new embodiments. After the various embodiments or technical features are combined, the original technical effects will be enhanced.

[0126] The above content is a further detailed description of the present application in conjunction with specific optional implementation methods, and the specific implementation of the present application cannot be considered to be limited to these descriptions. For ordinary technicians in the technical field to which the present application belongs, they can make several simple deductions or substitutions without departing from the concept of the present application, which should be considered to fall within the scope of protection of the present application.

Claims

1. A chip transfer method, characterized in that: Including steps: Providing a first substrate and a second substrate; preparing an epitaxial layer on the first substrate, and cutting the epitaxial layer to form a plurality of chips; forming a photoresist layer between two adjacent chips, and opening a hole at a position of the photoresist layer in contact with the chip, wherein the opening exposes the surface of the first substrate; preparing electrodes on the chip, and connecting the chip to the second substrate via the electrodes; performing a laser lift-off operation on a side of the epitaxial layer close to the first substrate to lift the epitaxial layer off from the first substrate; The photoresist layer is removed to separate the chip from the first substrate.

2. The chip transfer method according to claim 1, wherein: The steps of preparing an epitaxial layer on the first substrate and cutting the epitaxial layer to form a plurality of chips include: forming a U-type gallium nitride layer, an N-type gallium nitride layer, a multi-quantum well layer, and a P-type gallium nitride layer in sequence on the first substrate to form the epitaxial layer; performing a laser etching operation on the back surface of the U-shaped gallium nitride layer to form a plurality of channels; In the step of forming a photoresist layer between two adjacent chips and opening holes at positions of the photoresist layer in contact with the chips, a photoresist layer is formed in the plurality of channels and between two adjacent chips to fix the chips, and opening holes are opened at positions of the photoresist layer in contact with the chips; In the step of performing a laser lift-off operation on a side of the epitaxial layer close to the first substrate to lift the epitaxial layer off the first substrate, a lift-off laser is irradiated on the back surface of the U-shaped gallium nitride layer to lift the U-shaped gallium nitride layer off the first substrate, thereby lifting the epitaxial layer off the first substrate; In the step of removing the photoresist layer to separate the chip from the first substrate, the photoresist layer under the chip is removed to separate the chip from the first substrate.

3. The chip transfer method according to claim 2, wherein: The formed multiple channels are located below the chip, and the multiple channels are in a cross shape or a well shape, and both ends of each channel have openings.

4. The chip transfer method according to claim 3, characterized in that: At least two channels arranged at intervals are formed below each chip.

5. The chip transfer method according to claim 4, characterized in that: The width of each channel is greater than or equal to one third of the width of the epitaxial layer and less than one half of the width of the epitaxial layer.

6. The chip transfer method according to claim 5, characterized in that: The steps of forming a photoresist layer in the plurality of channels and between two adjacent chips to fix the chips, and opening holes at positions of the photoresist layer in contact with the chips include: Filling photoresist material in the plurality of channels and between two adjacent chips; performing a first heating and curing on the photoresist material to form a photoresist layer; By exposure and development, the opening is formed in the photoresist layer between two adjacent chips and in the portion contacting the chip; performing a second heating and curing on the photoresist layer; Wherein, the temperature of the second heating and curing is higher than the temperature of the first heating and curing.

7. The chip transfer method according to claim 6, characterized in that: The step of preparing electrodes on the chip and connecting the chip to the second substrate via the electrodes comprises: removing a portion of the multi-quantum well layer and the P-type gallium nitride layer above the N-type gallium nitride layer to expose a portion of the N-type gallium nitride layer, thereby forming a stepped chip; preparing a first electrode and a second electrode, wherein the first electrode is connected to the P-type gallium nitride layer; and the second electrode is connected to the N-type gallium nitride layer; The length of the first electrode is smaller than the length of the second electrode.

8. The chip transfer method according to claim 7, characterized in that: The step of performing lift-off laser irradiation on the back surface of the U-shaped gallium nitride layer to lift off the U-shaped gallium nitride layer from the first substrate comprises: The back surface of the U-shaped gallium nitride layer is irradiated with laser for a first preset time to remove the U-shaped gallium nitride portion on the same layer as the photoresist under the chip.

9. The chip transfer method according to claim 7, wherein: The step of performing lift-off laser irradiation on the back surface of the U-shaped gallium nitride layer to lift off the U-shaped gallium nitride layer from the first substrate comprises: The back surface of the U-shaped gallium nitride layer is irradiated with laser light for a second preset time to completely remove the U-shaped gallium nitride layer.

10. A display panel comprising a second substrate and a plurality of chips, characterized in that: The plurality of chips are connected to the second substrate by the chip transfer method according to any one of claims 1 to 9.

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