Substrate thinning process and LED chip manufacturing method

Abstract

The invention discloses a substrate thinning process which comprises the following steps: providing a growth substrate which is provided with a front surface and a back surface opposite to the front surface, and the front surface is provided with a plurality of LED chips; providing a temporary support plate, and temporarily bonding the front surface of the growth substrate with the temporary support plate; the target thickness of the thinned growth substrate is determined, a stripping surface located in the growth substrate is determined according to the target thickness, laser is adopted to move along a preset moving path and irradiate the growth substrate so as to form continuous point light spots on the stripping surface, and the preset moving path is arranged corresponding to the structure of the stripping surface so that the action range of the point light spots can cover the stripping surface; and applying a pulling force to the back surface of the growth substrate to separate the growth substrate on the stripping surface to form a target substrate with a target thickness. According to the invention, the laser is adopted to irradiate the stripping surface of the growth substrate along the preset moving path, and the action range of the spot light spot covers the whole stripping surface, so that the growth substrate is thinned, the problem of cracking of the growth substrate is avoided, and the operation is convenient.

Description

Technical Field

[0001] The present invention relates to the field of display modules, and particularly to a substrate thinning process and a method for manufacturing an LED chip. Background Art

[0002] In the existing LED chip manufacturing process, sapphire substrates are generally used for processes such as epitaxial growth and etching to form individual LED chips on the surface of the sapphire substrate. The prepared LED chips need to be separated from the sapphire substrate.

[0003] In the existing Mini / Micro LED chip manufacturing process, epitaxial growth and etching are generally performed on a growth substrate (commonly a sapphire substrate) to form a number of individual LED chips. There are generally two methods for dealing with the connection relationship between the LED chip and the growth substrate. One is laser lift-off (LLO), that is, a specific laser band is used to irradiate the buffer layer (generally AlN) between the LED chip and the growth substrate. The buffer layer absorbs the laser energy and decomposes, thereby separating the LED chip from the growth substrate. In this case, the light-emitting surface of the LED chip loses the protection of the growth substrate, and the defect rate of the LED chip will increase during the subsequent process of using the LED chip to manufacture LED display products. The other method is to grind and thin the growth substrate and perform dicing and stamping along the gaps between the individual LED chips to obtain a number of individual LED chips with a part of the growth substrate still on the light-emitting surface. The advantage of this kind of LED chip is that it retains the growth substrate for protection. The disadvantage is that the thickness reduction of the growth substrate by grinding and thinning is limited. When the growth substrate is ground and thinned to a certain thickness (the thickness of the growth substrate is reduced to about 200 um), the problem of cracking of the growth substrate will occur, so it is impossible to continue grinding and thinning. Therefore, in order to retain the protection of the growth substrate and further reduce the thickness of the growth substrate on the light-emitting surface of the LED chip, this solution is proposed. Summary of the Invention

[0004] The purpose of the present invention is to provide a substrate thinning process and a method for manufacturing an LED chip to solve the problem of cracking of the growth substrate caused by the existing grinding and thinning method.

[0005] To achieve the above object, a substrate thinning process provided by the present invention includes the following steps: providing a growth substrate having a front surface and a back surface opposite to the front surface, with a plurality of LED chips on the front surface; providing a temporary carrier, and temporarily bonding the front surface of the growth substrate to the temporary carrier; determining the target thickness after thinning of the growth substrate, determining a separation plane located in the growth substrate according to the target thickness, moving a laser along a preset moving path and irradiating the growth substrate to form continuous dot light spots on the separation plane, where the preset moving path is set corresponding to the structure of the separation plane so that the action range of the dot light spots covers the separation plane; applying a pulling force to the back surface of the growth substrate to separate the growth substrate at the separation plane to form a target substrate having the target thickness.

[0006] Preferably, the preset moving path includes multiple longitudinal paths and / or includes multiple transverse paths, or the preset moving path includes multiple annular paths in a ring structure.

[0007] Preferably, the preset moving path moves from a starting point on one side along multiple parallel longitudinal paths to an ending point on the other side, and the ends of adjacent two longitudinal paths are connected by a first transition line to form a continuous moving path.

[0008] Preferably, the annular path has the same contour structure as the separation plane and multiple annular paths are concentrically arranged. The preset moving path moves gradually from a starting point on one side along multiple annular paths towards the center, and adjacent annular paths are connected to each other by a second transition line to form a continuous moving path.

[0009] Preferably, the preset moving path further includes at least one ventilation path extending from the outer edge to the inner side for forming a channel communicating with the outside on the separation plane.

[0010] Preferably, the annular path includes several first annular paths and at least one second annular path located outside the first annular paths. The preset moving path includes a first moving path and a second moving path. The first moving path includes the several first annular paths, and the second moving path includes the at least one second annular path. The ventilation path extends towards the first annular path and is connected to the first annular path for forming a channel communicating with the outside on the separation plane; the step of moving a laser along the preset moving path and irradiating the growth substrate to form continuous dot light spots on the separation plane includes: moving a laser along the ventilation path, the first moving path, and the second moving path in sequence and irradiating the growth substrate to form continuous dot light spots on the separation plane.

[0011] Preferably, the circular path includes a plurality of first semi-circular paths and a plurality of second semi-circular paths that are symmetrically arranged. The circular path further includes at least one third semi-circular path and at least one fourth semi-circular path that are symmetrically arranged. The third semi-circular path surrounds the first semi-circular path, and the fourth semi-circular path surrounds the second semi-circular path. The ventilation path includes a first ventilation path and a second ventilation path that are symmetrically arranged. The preset movement path includes a third movement path, a fourth movement path, a fifth movement path, and a sixth movement path. The third movement path includes the plurality of first semi-circular paths, the fourth movement path includes the plurality of second semi-circular paths, the fifth movement path includes the at least one third semi-circular path, and the sixth movement path includes the at least one fourth semi-circular path. The first ventilation path is at least one and extends towards the first semi-circular path, and the second ventilation path is at least one and extends towards the second semi-circular path. The step of using a laser to move along the preset movement path and irradiate the growth substrate to form continuous dot light spots on the peeling surface includes: using a first laser to move along the first ventilation path and irradiate the growth substrate, and at the same time using a second laser to move along the second ventilation path and irradiate the growth substrate, and making the first laser and the second laser move symmetrically with respect to the center of the circular path; then using the first laser to move along the third movement path and irradiate the growth substrate, and at the same time using the second laser to move along the fourth movement path and irradiate the growth substrate, and making the first laser and the second laser move symmetrically with respect to the center of the circular path; afterwards using the first laser to move along the fifth movement path and irradiate the growth substrate, and at the same time using the second laser to move along the sixth movement path and irradiate the growth substrate, and making the first laser and the second laser move symmetrically with respect to the center of the circular path.

[0012] Preferably, the step of using a laser to move along the preset movement path and irradiate the growth substrate to form continuous dot light spots on the peeling surface includes: using a third laser to move along the preset movement path and irradiate the growth substrate to form continuous dot light spots on the peeling surface, and simultaneously using a fourth laser to move along the preset movement path and irradiate the growth substrate to form another layer of continuous dot light spots at a preset distance above the peeling surface to form two cutting surfaces.

[0013] Preferably, the acting positions of adjacent dot light spots in the direction of the preset movement path partially overlap.

[0014] Preferably, applying a tensile force to the back surface of the growth substrate to separate the growth substrate at the peeling surface to form a target substrate with the target thickness includes: applying a tensile force to the back surface of the growth substrate to separate and form a first substrate at the peeling surface; chemically cleaning and baking the first substrate, and processing its back surface into a smooth mirror surface to form a target substrate.

[0015] An embodiment of the present invention also discloses a method for manufacturing an LED chip, including the following steps: thinning the growth substrate by using the above substrate thinning process; cutting the growth substrate along the gap between adjacent LED chips to form a plurality of single LED chips; providing a temporary carrier film, and attaching one side of the plurality of single LED chips facing away from the temporary carrier plate to the temporary carrier film; separating the temporary carrier plate to transfer the plurality of single LED chips to the temporary carrier film.

[0016] Compared with the prior art, the present invention thins the growth substrate by irradiating the peeling surface of the growth substrate with a laser along a preset moving path so that the action range of the point light spot covers the entire peeling surface, avoiding the problem of cracking of the growth substrate, with novel design and convenient operation. Description of the Drawings

[0017] Figure 1 It is a schematic structural diagram of a growth substrate provided with a plurality of LED chips in an embodiment of the present invention after being bonded to a temporary carrier plate.

[0018] Figure 2 It is a schematic structural diagram of a laser acting on the peeling surface from the back surface of the growth substrate in an embodiment of the present invention.

[0019] Figure 3 It is a schematic structural diagram of a laser light spot acting on the peeling surface in an embodiment of the present invention.

[0020] Figure 4 It is a structural diagram of using a third laser and a fourth laser to act on the peeling surface and above the peeling surface respectively in an embodiment of the present invention.

[0021] Figure 5 It is a schematic structural diagram of the growth substrate thinned in an embodiment of the present invention.

[0022] Figure 6 It is a schematic structural diagram of a preset moving path in an embodiment of the present invention in one implementation manner.

[0023] Figure 7 It is a schematic structural diagram of a preset moving path in another implementation manner of an embodiment of the present invention.

[0024] Figure 8 It is a schematic structural diagram of a preset moving path in yet another implementation manner of an embodiment of the present invention.

[0025] Figure 9 Schematic diagram of a preset moving path under another implementation manner of the embodiment of the present invention.

[0026] Figure 10 Schematic diagram of the structure for cutting the thinned growth substrate by laser in the embodiment of the present invention to obtain single LED chips.

[0027] Figure 11 Schematic diagram of the structure of a single LED chip disposed on a temporary carrier after cutting the thinned growth substrate by laser in the embodiment of the present invention.

[0028] Figure 12 Schematic diagram of the structure after disposing a single LED chip on a temporary carrier film in the embodiment of the present invention.

[0029] Figure 13 Schematic diagram of the structure of the LED chip after separating the temporary carrier in the embodiment of the present invention. Specific embodiments

[0030] To describe in detail the technical content, structural features, and achieved effects of the present invention, the following is a detailed description in conjunction with the embodiments and with reference to the accompanying drawings.

[0031] As Figures 1 to 13 shown, the embodiment of the present invention discloses a substrate thinning process, which includes the following steps:

[0032] S1. Provide a growth substrate 1, the growth substrate 1 has a front surface 11 and a back surface 12 opposite to the front surface 11, and a plurality of LED chips 2 are disposed on the front surface 11; specifically, as Figure 1 shown, the growth substrate 1 is a wafer structure, and can be a transparent substrate such as sapphire or silicon nitride. An epitaxial structure layer is fabricated on the surface of the growth substrate 1 through an epitaxial growth process. The epitaxial structure layer includes a buffer layer, an N-type gallium nitride layer, a light-emitting layer, and a P-type gallium nitride layer. Through processes such as photolithography, etching, thin film deposition, evaporation plating, and electroplating, the epitaxial structure layer is patterned and electrodes 3 are formed, thereby fabricating a plurality of LED chips 2 on the surface of the growth substrate 1. The LED chips 2 are arranged in an array on the growth substrate 1. The LED chips 2 are flip-chip structures, and the two electrodes 3 of the LED chips 2 both face away from the growth substrate 1, and the two electrodes 3 of the LED chips 2 are an N-type electrode and a P-type electrode respectively.

[0033] S2. Provide a temporary carrier 4, and temporarily bond the front surface 11 of the growth substrate 1 to the temporary carrier 4; specifically, as Figure 1As shown, a temporary bonding layer 5 is formed on the surface of the temporary carrier 4 by spin coating or attaching. The side of the growth substrate 1 with the LED chips 2 is bonded to the side of the temporary carrier 4 with the temporary bonding layer 5. The electrodes 3 of the LED chips 2 are fixed to the temporary bonding layer 5 on the temporary carrier 4. The temporary carrier 4 is preferably made of a transparent material, such as a glass carrier. The temporary bonding layer 5 can be a double-sided UV adhesive attached to the temporary carrier 4 or a UV film spin-coated on the temporary carrier 4. When it is necessary to separate the LED chips 2 from the temporary carrier 4, only the double-sided UV adhesive or the UV film needs to be irradiated with ultraviolet light. Of course, the temporary bonding layer 5 can also be other adhesive materials, such as a high-temperature adhesive that can be debonded under high-temperature conditions or a thermal-debonding adhesive that can be debonded under heated conditions, etc.

[0034] S3. Determine the target thickness of the thinned growth substrate 1, determine the peeling plane 13 in the growth substrate 1 according to the target thickness, and move and irradiate the growth substrate 1 with a laser along a preset moving path to form continuous dot light spots 61 on the peeling plane 13. The preset moving path is set corresponding to the structure of the peeling plane 13 so that the action range of the dot light spots 61 covers the peeling plane 13. Specifically, the dot light spots 61 are specifically formed by focusing the discontinuous laser emitted by the laser on the growth substrate 1. There is an interval between the action times of adjacent dot light spots 61 on the peeling plane. The energy of the dot light spots 61 causes crack points to be generated inside the growth substrate 1. The dot light spots 61 continuously and continuously create crack points along the preset moving path, thereby constituting the substantial peeling plane 13 of the pre-determined peeling plane 13, as Figures 2 to 3 shown. Determine the position of the peeling plane 13 where the laser 6 is to act in the growth substrate 1 according to the target thickness of the growth substrate 1 to be retained. The bonded growth substrate 1 and the temporary carrier 4 can be fixed on the operating table. The operating table and the laser for emitting the laser 6 can be moved relative to each other. The laser 6 emitted by the laser is focused to form dot light spots 61 on the growth substrate 1 and moves and irradiates the growth substrate 1 along the preset moving path. Preferably, the laser can irradiate the growth substrate 1 from the back surface 12 of the growth substrate 1. In order to better separate the growth substrate 1, the action positions of adjacent dot light spots 61 on the preset moving path partially overlap, and the action range of the dot light spots 61 covers the entire peeling plane 13. The action range of the dot light spots 61 can also partially exceed the peeling plane 13.

[0035] S4. Apply a pulling force to the back surface 12 of the growth substrate 1 to separate the growth substrate 1 at the peeling plane 13 to form a target substrate 14 with the target thickness. Specifically, as Figures 1 to 3 and Figure 5 shown. Since the laser 6 has caused crack points to be generated inside the growth substrate 1, by applying a pulling force to the back surface 12 of the growth substrate 1, the growth substrate 1 can be separated at the peeling plane 13, thereby realizing the thinning of the growth substrate 1.

[0036] In an embodiment of the present invention, the growth substrate 1 is thinned by irradiating the peeling surface 13 of the growth substrate 1 with a laser 6 along a preset moving path, and the action range of the point light spot 61 covers the entire peeling surface 13, thereby avoiding the problem of cracking of the growth substrate 1. The design is novel and the operation is convenient.

[0037] In an embodiment of the present invention, the preset moving path includes multiple longitudinal paths and / or multiple transverse paths, or the preset moving path includes multiple circular paths in a circular structure. Specifically, the preset moving path in the embodiment of the present invention may include multiple longitudinal paths, may also include multiple transverse paths, or may also include paths where multiple longitudinal paths and multiple transverse paths intersect. Of course, the preset moving path may also include multiple circular paths in a circular structure, as long as the moving path can cover the entire peeling surface 13 with the action range of the point light spot 61.

[0038] In a specific embodiment of the present invention, the preset moving path 7a moves from a starting point on one side along multiple parallel longitudinal paths 71 to an ending point on the other side, and the ends of adjacent two longitudinal paths 71 are connected by a first transition line 72 to form a continuous moving path. Specifically, as Figure 6 shown, for the growth substrate 1 with a wafer structure, the starting point of the preset moving path 7a is shown by an arrow e. The starting points and ending points of all longitudinal paths 71 are points on a circle, each longitudinal path 71 is a chord of the circle, and the first transition line 72 is an arc segment of the circle. The radius of the circle is equal to, slightly less than, or slightly greater than the radius of the growth substrate 1, as long as the growth substrate 1 can be separated from the peeling surface 13. In some other embodiments, the structure of the growth substrate 1 may not be limited to the wafer structure, for example, it may be a square wafer structure, etc.

[0039] In another specific embodiment of the present invention, the circular path has the same contour structure as the peeling surface 13, and multiple circular paths 73 are concentrically arranged. The preset moving path moves gradually from a starting point on one side along multiple circular paths 73 towards the center, and adjacent circular paths 73 are connected to each other through a second transition line 74 to form a continuous moving path. Specifically, as Figure 7As shown, in two adjacent circular paths 73, the outer circular path 73 and the inner circular path 73 are connected to each other by a second transition line 74 to form a continuous movement path. For the growth substrate 1 with a wafer structure, the contour of the peeling surface 13 is circular, the circular path 73 is circular, the radius of the inner circular path 73 is smaller than that of the outer circular path 73, and the starting point and the ending point of the circular path 73 can be the same point or two points with a small spacing. The starting point of the preset movement path 7b is shown by an arrow h. By performing laser 6 treatment step by step from the edge of the growth substrate 1 towards the center of the growth substrate 1, the edge of the growth substrate 1 is first separated and gradually separated towards the center. The overall energy impact on the growth substrate 1 is relatively balanced, reducing the possibility of the growth substrate 1 cracking. In some other embodiments, the structure of the growth substrate 1 is not limited to the wafer structure. For example, it can be a square wafer structure, etc. At this time, the circular path 73 is also a square structure. In some other specific embodiments, multiple circular paths 73 in a circular structure can also be a continuous spiral structure.

[0040] In the embodiment of the present invention, the preset movement path further includes at least one ventilation path extending from the outer edge to the inner side for forming a channel communicating with the outside on the peeling surface 13. Specifically, the ventilation path is connected to the longitudinal path and / or the transverse path, or the ventilation path is connected to the circular path.

[0041] In another specific embodiment of the embodiment of the present invention, the circular path includes a plurality of first circular paths 76 and at least one second circular path 78 located outside the first circular paths 76. The preset movement path includes a first movement path and a second movement path. The first movement path includes a plurality of first circular paths 76, and the second movement path includes at least one second circular path 78. The ventilation path 75 extends towards the first circular paths 76 and is connected to the first circular paths 76 for forming a channel communicating with the outside on the peeling surface 13. In step S3, the step of moving the laser 6 along the preset movement path and irradiating the growth substrate to form continuous dot light spots 61 on the peeling surface 13 includes:

[0042] S31. Move the laser 6 along the ventilation path 75, the first movement path, and the second movement path in sequence and irradiate the growth substrate 1 to form continuous dot light spots 61 on the peeling surface 13. Specifically, as Figure 8As shown, the preset moving path 7c includes a ventilation path 75, a first moving path, and a second moving path. There is at least one ventilation path 75 and each ventilation path 75 is connected to a first annular path 76, one end of one ventilation path is a starting point, and the first moving path is a first annular path 76 with the same structure as the contour of the peeling surface 13, which gradually moves toward the center. Each first annular path 76 has a starting point and an end point. Among two adjacent first annular paths 76, the end point of the first annular path 76 located on the outer side and the starting point of the first annular path 76 located on the inner side are connected to each other through a third transition line 77 to form a continuous The first moving path is a first moving path, and the second moving path is to move from the starting point along the second annular path 78 with the same structure as the peeling surface 13 to the starting point or a position close to the starting point. The second annular path 78 surrounds the first annular path 76. For the growth substrate 1 with a wafer structure, the contour of the peeling surface 13 is circular, and the first annular path 76 and the second annular path 78 are both circular. The starting point is shown by the arrow g. The radius of the first annular path 76 located on the inner side is smaller than the radius of the first annular path 76 located on the outer side. The starting point and the end point of the first annular path 76 can be the same point or two points with a small spacing. The second moving path includes at least one second annular path 78. The laser 6 starts from the starting point of the edge, as shown by the arrow g, and first executes the ventilation path 75 to form at least one exhaust channel to keep the peeling surface 13 acted by the laser 6 connected to the outside world. At the same time, the ventilation path 75 has a certain length to reserve the edge position, and then the laser 6 is gradually processed toward the center of the growth substrate 1 through the first moving path. Finally, the edge position of the growth substrate 1 is processed by the laser 6 through the second moving path. During the separation process, the material of the growth substrate 1 itself is decomposed and vaporized, and the peeling surface 13 remains connected to the outside world, which can avoid the situation where the internal air pressure increases and causes cracks. The reserved edge position can play a fixing role to avoid the two sides of the peeling surface 13 of the growth substrate 1 from separating too early.

[0043] In another specific embodiment of the embodiment of the present invention, the annular path includes a plurality of first semi-annular paths 702 and a plurality of second semi-annular paths 705 that are symmetrically arranged. The annular path further includes at least one third semi-annular path 707 and at least one fourth semi-annular path 708 that are symmetrically arranged. The third semi-annular path 707 is arranged to surround the first semi-annular path 702, and the fourth semi-annular path 708 is arranged to surround the second semi-annular path 705. The ventilation path includes a first ventilation path 701 and a second ventilation path 704 that are symmetrically arranged. The preset movement path includes a third movement path, a fourth movement path, a fifth movement path, and a sixth movement path. The third movement path includes a plurality of first semi-annular paths 702, the fourth movement path includes a plurality of second semi-annular paths 705, the fifth movement path includes at least one third semi-annular path 707, and the sixth movement path includes at least one fourth semi-annular path 708. The first ventilation path 701 is at least one and the first ventilation path 701 extends towards the first semi-annular path 702, and the second ventilation path 704 is at least one and the second ventilation path 704 extends towards the second semi-annular path 705; in step S3, the step of moving a laser along the preset movement path and irradiating the growth substrate 1 to form continuous dot light spots on the peeling surface 13 includes:

[0044] S301. Move and irradiate the growth substrate 1 with a first laser along the first ventilation path 701 and at the same time move and irradiate the growth substrate 1 with a second laser along the second ventilation path 704, and make the first laser and the second laser move symmetrically with respect to the center of the annular path. Specifically, as Figure 9As shown, the preset moving path 7d includes a first starting point, as shown by arrow m, and a second starting point, as shown by arrow n, which are relatively arranged. The line connecting the first starting point and the second starting point passes through the center of the preset moving path 7d. The first semi-annular path 702 and the second semi-annular path 705 are symmetrically arranged on both sides of the connecting line. The third semi-annular path 707 and the fourth semi-annular path 708 are symmetrically arranged on both sides of the connecting line. Each first semi-annular path 702 has a starting point and an end point. In two adjacent first semi-annular paths 702, the end point of the first semi-annular path 702 located on the outer side and the starting point of the first semi-annular path 702 located on the inner side are connected to each other through the fourth transition line 703 to form a connecting line. The third moving path that continuously advances toward the center of the preset moving path, each second semi-annular path 705 has a starting point and an end point, and in two adjacent second semi-annular paths 705, the end point of the second semi-annular path 705 located on the outer side and the starting point of the second semi-annular path 705 located on the inner side are connected to each other through a fifth transition line 706 to form a fourth moving path that continuously advances toward the center of the preset moving path; the fifth moving path is to move from the first starting point along the third semi-annular path 707 to the second starting point or close to the second starting point, and the third semi-annular path 707 surrounds the first semi-annular path 702; the sixth moving path is to move from the second starting point along the fourth semi-annular path 708 to the first The fourth semi-annular path 708 surrounds the second semi-annular path 705, one end of the first ventilation path 701 is connected to the first starting point, and the other end of the first ventilation path 701 is connected to the first semi-annular path 702, one end of the second ventilation path 704 is connected to the second starting point, and the other end of the second ventilation path 704 is connected to the second semi-annular path 705. For the growth substrate 1 of the wafer structure, the contour of the peeling surface 13 is circular, and the first semi-annular path 702 and the second semi-annular path 705 are both semi-circular. The radius of the first semi-annular path 702 located on the inner side is smaller than the radius of the first semi-annular path 702 located on the outer side. Similarly, the inner semi-annular path 702 is connected to the second starting point. The radius of the second semi-annular path 705 on the side is smaller than the radius of the second semi-annular path 705 on the outside, the first laser is used to irradiate the growth substrate 1 along the first ventilation path 701 from the first starting point and the second laser is used to irradiate the growth substrate 1 along the second ventilation path 704 from the second starting point, the first ventilation path 701 and the second ventilation path 701 are symmetrically arranged and the first laser and the second laser are moved symmetrically, and at least one exhaust channel can be formed respectively to keep the peeling surface 13 acted by the laser 6 connected to the outside, and at the same time, the first ventilation path 701 and the second ventilation path 704 have a certain length to reserve edge position, which can avoid the situation where the internal air pressure increases and causes cracks.

[0045] S302. Then, move and irradiate the growth substrate 1 with the first laser along the third moving path, and at the same time, move and irradiate the growth substrate 1 with the second laser along the fourth moving path, and make the first laser and the second laser move symmetrically with respect to the center of the circular path.

[0046] S303. Then, move and irradiate the growth substrate 1 with the first laser along the fifth moving path, and at the same time, move and irradiate the growth substrate 1 with the second laser along the sixth moving path, and make the first laser and the second laser move symmetrically with respect to the center of the circular path. Specifically, both the third semi-circular path 707 and the fourth semi-circular path 708 are semi-circular. The fifth moving path and the sixth moving path are symmetric with respect to the center of the circular path, which can also keep the energy impact received by the entire growth substrate 11 relatively balanced, and can improve the separation efficiency of the growth substrate 1. In addition, the reserved edge position in this embodiment can play a fixing role to prevent the two sides of the peeling surface 13 of the growth substrate 1 from separating prematurely.

[0047] In some other embodiments of the present invention, in step S3, moving and irradiating the growth substrate with a laser along a preset moving path to form continuous dot light spots on the peeling surface includes:

[0048] S30. Move and irradiate the growth substrate 1 with the third laser along the preset moving path to form continuous dot light spots on the peeling surface 13, and at the same time, move and irradiate the growth substrate 1 with the fourth laser along the preset moving path to form another layer of continuous dot light spots at a preset distance above the peeling surface 13 to form two cutting surfaces. Specifically, as Figure 4 shown, move and irradiate the growth substrate 1 with the third laser 62 along the preset moving path to form continuous dot light spots 64 on the peeling surface 13, and at the same time, move and irradiate the growth substrate 1 with the fourth laser 63 along the preset moving path to form another layer of continuous dot light spots 65 at a preset distance above the peeling surface 13 to form two cutting surfaces. The preset distance is very small, and the distance between the two cutting surfaces is very close to facilitate substrate separation more conveniently. Of course, in some other embodiments, more than two cutting surfaces can also be formed, and the specific number of layers is determined according to the actual separation effect.

[0049] In the embodiment of the present invention, the target thickness is less than or equal to 100 microns. The target thickness is very thin, and it is very easy to crack using the conventional grinding and thinning scheme. However, in the embodiment of the present invention, on the basis of thinning the growth substrate 1, the integrity of the thinned growth substrate 1 is effectively guaranteed.

[0050] In the embodiment of the present invention, step S4, applying a pulling force to the back surface 12 of the growth substrate 1 to separate the growth substrate 1 on the peeling surface 13 to form a target substrate 14 with a target thickness includes:

[0051] S41. Apply a tensile force to the back surface 12 of the growth substrate 1 to separate it at the peeling surface 13 and form the first substrate. Specifically, for the growth substrate 1 after laser 6 treatment, only by applying a tensile force to the back surface 12 of the growth substrate 1 can the growth substrate 1 be separated at the peeling surface 13.

[0052] S42. Chemically clean and bake the first substrate, and process its back surface 12 into a smooth mirror surface to form the target substrate 14.

[0053] The embodiment of the present invention also discloses a method for manufacturing an LED chip, including the following steps:

[0054] S10. Thin the growth substrate 1 using the above substrate thinning process.

[0055] S20. Cut the growth substrate 1 along the gaps between adjacent LED chips 2 to form a plurality of single LED chips 9. Specifically, as Figures 10 to 11 shown, the fifth laser 8 can be used to cut the LED chips 2 and form single LED chips 9 including a growth substrate 1 with a certain thickness.

[0056] S30. Provide a temporary carrier film 10, and attach the side of a plurality of single LED chips 9 facing away from the temporary carrier plate 4 to the temporary carrier film 10. Specifically, as Figure 12 shown, the temporary carrier film 10 can be a blue film.

[0057] S40. Separate the temporary carrier plate 4 to transfer a plurality of single LED chips 9 to the temporary carrier film 10. By transferring the single LED chips 9 to the temporary carrier film 10, the electrodes 3 of the LED chips 2 are exposed for subsequent welding and other processes, as specifically Figure 13 shown.

[0058] The above-disclosed are only the preferred examples of the present invention. Of course, the scope of the rights of the present invention cannot be limited by this. Therefore, equivalent changes made according to the scope of the patent application of the present invention still fall within the scope covered by the present invention.

Claims

1. A substrate thinning process, characterized in that, The method includes the following steps: Provide a growth substrate having a front side and a back side opposite to the front side, with a plurality of LED chips on the front side; Provide a temporary carrier plate and temporarily bond the front side of the growth substrate to the temporary carrier plate; Determine the target thickness after thinning the growth substrate, determine the separation plane located in the growth substrate according to the target thickness, and use a laser to move along a preset movement path and irradiate the growth substrate to form continuous dot-shaped light spots on the separation plane. The preset movement path is set corresponding to the structure of the separation plane so that the action range of the dot-shaped light spots covers the separation plane; Apply a pulling force to the back side of the growth substrate to separate the growth substrate at the separation plane to form a target substrate having the target thickness.

2. The substrate thinning process according to claim 1, wherein The preset movement path includes multiple longitudinal paths and / or multiple transverse paths, or the preset movement path includes multiple circular paths in a circular structure.

3. The substrate thinning process according to claim 2, wherein, The preset movement path moves from a starting point on one side along multiple parallel longitudinal paths to an ending point on the other side, and the ends of adjacent two longitudinal paths are connected by a first transition line to form a continuous movement path.

4. The substrate thinning process according to claim 2, wherein The circular path has the same contour structure as the separation plane, and multiple circular paths are concentrically arranged. The preset movement path moves gradually from a starting point on one side along the multiple circular paths towards the center, and adjacent circular paths are connected to each other by a second transition line to form a continuous movement path.

5. The substrate thinning process according to claim 2, wherein The preset movement path further includes at least one ventilation path extending from the outer edge to the inner side for forming a channel communicating with the outside on the separation plane.

6. The substrate thinning process according to claim 5, wherein, The circular path includes a plurality of first circular paths and at least one second circular path located outside the first circular paths. The preset movement path includes a first movement path and a second movement path. The first movement path includes the plurality of first circular paths, and the second movement path includes the at least one second circular path. The ventilation path extends towards the first circular paths and is connected to the first circular paths for forming a channel communicating with the outside on the separation plane; The step of using a laser to move along a preset movement path and irradiate the growth substrate to form continuous dot-shaped light spots on the separation plane includes: Use a laser to move along the ventilation path, the first movement path, and the second movement path in sequence and irradiate the growth substrate to form continuous dot-shaped light spots on the separation plane.

7. The substrate thinning process according to claim 5, wherein The annular path includes a plurality of first semi-annular paths and a plurality of second semi-annular paths that are symmetrically arranged. The annular path further includes at least one third semi-annular path and at least one fourth semi-annular path that are symmetrically arranged. The third semi-annular path surrounds the first semi-annular path, and the fourth semi-annular path surrounds the second semi-annular path. The ventilation path includes a first ventilation path and a second ventilation path that are symmetrically arranged. The preset movement path includes a third movement path, a fourth movement path, a fifth movement path, and a sixth movement path. The third movement path includes the plurality of first semi-annular paths, the fourth movement path includes the plurality of second semi-annular paths, the fifth movement path includes the at least one third semi-annular path, and the sixth movement path includes the at least one fourth semi-annular path. The first ventilation path is at least one and extends towards the first semi-annular path, and the second ventilation path is at least one and extends towards the second semi-annular path. The step of using a laser to move along the preset movement path and irradiate the growth substrate to form continuous dot light spots on the peeling surface includes: Using a first laser to move along the first ventilation path and irradiate the growth substrate, and simultaneously using a second laser to move along the second ventilation path and irradiate the growth substrate, and making the first laser and the second laser move symmetrically with respect to the center of the annular path; Then using the first laser to move along the third movement path and irradiate the growth substrate, and simultaneously using the second laser to move along the fourth movement path and irradiate the growth substrate, and making the first laser and the second laser move symmetrically with respect to the center of the annular path; Subsequently using the first laser to move along the fifth movement path and irradiate the growth substrate, and simultaneously using the second laser to move along the sixth movement path and irradiate the growth substrate, and making the first laser and the second laser move symmetrically with respect to the center of the annular path.

8. The substrate thinning process according to claim 1, wherein, The step of using a laser to move along the preset movement path and irradiate the growth substrate to form continuous dot light spots on the peeling surface includes: Using a third laser to move along the preset movement path and irradiate the growth substrate to form continuous dot light spots on the peeling surface, and simultaneously using a fourth laser to move along the preset movement path and irradiate the growth substrate to form another layer of continuous dot light spots at a preset distance above the peeling surface to form two cutting surfaces.

9. The substrate thinning process according to claim 1, wherein The acting positions of adjacent dot light spots in the direction of the preset movement path partially overlap.

10. The substrate thinning process according to claim 1, characterized in that, Applying a pulling force to the back surface of the growth substrate to separate the growth substrate at the peeling surface to form a target substrate with the target thickness includes: Applying a pulling force to the back surface of the growth substrate to separate and form a first substrate at the peeling surface; Performing chemical cleaning and baking treatments on the first substrate, and processing its back surface into a smooth mirror surface to form a target substrate.

11. A method for manufacturing an LED chip, characterized in that, Including the following steps: Thinning the growth substrate using the substrate thinning process according to any one of claims 1 to 10; The growth substrate is cut along the gaps between adjacent LED chips to form a plurality of single LED chips; A temporary carrier film is provided, and one side of the plurality of single LED chips facing away from the temporary carrier plate is attached to the temporary carrier film; The temporary carrier plate is separated to transfer the plurality of single LED chips onto the temporary carrier film.

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