Mini LED chip and preparation method thereof

Abstract

The invention relates to the technical field of photoelectricity, and discloses a Mini LED chip and a preparation method thereof, and the method comprises the steps: providing a Mini LED chip wafer, the Mini LED chip wafer comprises a substrate, the substrate is sequentially provided with a chip layer, the surface of the chip layer is provided with a bonding pad, and the bonding pad comprises a magnetic attraction layer; the Mini LED chip wafer is fixed on a grinding machine through a magnetic disc, and a substrate of the Mini LED chip wafer is thinned, so that a first wafer is obtained; attaching a temporary substrate to the substrate of the first wafer, and separating the magnetic disc from the first wafer to obtain a second wafer; and the second wafer is cut, so that a single Mini LED chip can be obtained. The preparation method of the Mini LED chip provided by the invention can realize low wafer thickness and high yield.

Description

Technical Field

[0001] The present invention relates to the field of optoelectronic technology, and in particular to a Mini LED chip and a method for preparing the same. Background Art

[0002] Flip-chip Mini LED chips can be used in COB direct display solutions. They can achieve high-definition and high-resolution display through the separate control of RGB three-primary color chips. They have the advantages of rich colors, energy saving, long life, and light weight, and are gradually becoming mainstream in the display market. The current mini chips are thinned by grinding and polishing. The thickness of the thinned wafer is generally 60μm to 85μm, and the size is generally around 3*6mil. The Mini LED wafer is cut into chips by laser hidden cutting, and then the chips are classified by photoelectric testing. According to the classification principle, the so-called bin table is used to sort out the chips with the specifications and parameters that customers want. The packaging application end fixes the Mini LED chip on the PCB substrate by bonding, and realizes electrical connection with the substrate through reflow soldering, and at the same time sticks the Mini LED chip to the PCB.

[0003] The current mini chip wafer thickness after thinning is about 80μm, which is very thin. It is easy to break during the thinning process. Even after the thinning is completed, it will break during the subsequent process. During the cutting process, the wafer will be severely warped because it is too thin, resulting in a low cutting yield. If you want to further thin it to less than 60μm, the probability of breaking will be very high, and it will not be possible to operate at all, which also makes it impossible for the chip to be less than 60μm thick. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for preparing a Mini LED chip, which has a low wafer thickness and a high yield rate.

[0005] The technical problem to be solved by the present invention is also to provide a Mini LED chip.

[0006] In order to solve the above technical problems, the present invention provides a method for preparing a Mini LED chip, comprising the following steps:

[0007] A Mini LED chip wafer is provided, wherein the Mini LED chip wafer comprises a substrate, on which chip layers are sequentially arranged, a solder pad is arranged on a surface of the chip layer, and the solder pad comprises a magnetic attraction layer;

[0008] Fixing the Mini LED chip wafer on a grinder via a magnetic disk, and thinning the substrate of the Mini LED chip wafer to obtain a first wafer;

[0009] Laminating the temporary substrate and the substrate of the first wafer together, and separating the magnetic disk from the first wafer to obtain a second wafer;

[0010] The second wafer is cut to obtain a single Mini LED chip.

[0011] In some embodiments, the pad includes a contact layer, a reflective layer, a cladding layer, a barrier layer, and a magnetic attraction layer connected sequentially from bottom to top;

[0012] The contact layer includes one or more of Cr, Ni, and Ti;

[0013] The reflective layer comprises Al;

[0014] The coating layer includes one or more of Ti, Ni, and Pt;

[0015] The barrier layer comprises Ti;

[0016] The magnetic attraction layer includes Ni.

[0017] In some embodiments, a protective layer is further provided on the magnetic attraction layer, and the protective layer includes Au.

[0018] In some embodiments, the thickness of the contact layer is 3 nm to 10 nm;

[0019] The thickness of the reflective layer is 100nm to 300nm;

[0020] The coating layer has a thickness of 100 nm to 300 nm;

[0021] The thickness of the barrier layer is 100nm to 500nm;

[0022] The thickness of the magnetic attraction layer is 300nm-5000nm.

[0023] The thickness of the protective layer is 10nm-50nm.

[0024] In some embodiments, fixing the Mini LED chip wafer on a grinding machine via a magnetic plate includes:

[0025] The grinding machine is provided with a magnetic disk, which becomes magnetic when powered on, so that the magnetic disk is magnetically fixed to the Mini LED chip wafer.

[0026] In some embodiments, the thickness of the substrate of the first wafer is ≤80 μm.

[0027] In some embodiments, the temporary substrate is a transparent substrate with a thickness of 20 μm to 100 μm.

[0028] In some embodiments, the temporary substrate is bonded to the substrate of the first wafer via a UV adhesive layer.

[0029] In some implementations, the separating the magnetic disk and the first wafer is achieved by powering off the magnetic disk.

[0030] In order to solve the above technical problems, the present invention also provides a Mini LED chip, and the Mini LED chip is manufactured by the Mini LED chip manufacturing method as described above.

[0031] The implementation of the present invention has the following beneficial effects:

[0032] The preparation method of the Mini LED chip provided by the present invention, wherein the Mini LED chip wafer includes a substrate, a chip layer is sequentially arranged on the substrate, a soldering pad is arranged on the surface of the chip layer, and the soldering pad includes a magnetic attraction layer. A subsequent grinder uses a magnetic disk to absorb the magnetic attraction layer of the Mini LED chip wafer to fix the wafer, and the wafer is fixed and released by powering on. At the same time, a temporary substrate is used to fix the Mini LED chip wafer to avoid cracking and warping of the Mini LED chip wafer, reduce wafer fragments, and also avoid the problem of low cutting yield caused by wafer warping during cutting. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the structure of a Mini LED chip wafer in a method for preparing a Mini LED chip provided in an embodiment of the present invention;

[0034] Figure 2 This is a schematic diagram of the structure of a solder pad in a method for preparing a Mini LED chip provided in an embodiment of the present invention;

[0035] Figure 3 This is a structural schematic diagram of a Mini LED chip wafer being fixedly connected to a magnetic disk in a method for preparing a Mini LED chip provided in an embodiment of the present invention;

[0036] Figure 4 A schematic structural diagram of laminating a temporary substrate and a substrate of the first wafer together in a method for preparing a Mini LED chip provided in an embodiment of the present invention;

[0037] Figure 5 This is a structural schematic diagram of the Mini LED chip wafer after the front side is bonded to the blue film and cut in the method for preparing the Mini LED chip provided in one embodiment of the present invention. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. In addition, it should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0039] In the description of the present invention, it is necessary to understand that the terms "length", "width", "up", "down", "left", "right", "horizontal", "top", "bottom", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0040] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0041] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0042] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0043] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the examples of various specific processes and materials provided by the present invention, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0044] In the present invention, "preferred" and "better" are only used to describe implementation methods or embodiments with better effects, and it should be understood that they do not constitute a limitation on the scope of protection of the present invention. In the present invention, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features. In the present invention, when involving numerical ranges, unless otherwise specified, the two endpoints of the numerical range are included.

[0045] To solve the above problems, the present invention provides a method for preparing a Mini LED chip, comprising the following steps:

[0046] (1) Figure 1 As shown, a Mini LED chip wafer is provided, the Mini LED chip wafer includes a substrate 100, a chip layer 200 is sequentially arranged on the substrate 100, a pad 300 is arranged on the surface of the chip layer 200, and the pad 300 includes a magnetic attraction layer 350;

[0047] like Figure 2 As shown, in some implementations, the pad 300 includes an N pad 300 and a P pad 300 , and the materials, structures, and heights of the two pads 300 are consistent.

[0048] In some embodiments, the pad 300 includes a contact layer 310, a reflective layer 320, a cladding layer 330, a barrier layer 340, and a magnetic attraction layer 350 connected sequentially from bottom to top;

[0049] The contact layer 310 includes one or more of Cr, Ni, and Ti; the thickness of the contact layer 310 is 3nm to 10nm, and exemplary thicknesses are 4nm, 5nm, 6nm, 7nm, 8nm, and 9nm, but are not limited to the above; the contact layer 310 needs to have good conductivity to ensure smooth transmission of current or signals.

[0050] The reflective layer 320 includes Al; the thickness of the reflective layer 320 is 100nm to 300nm, and exemplary thicknesses are 120nm, 150nm, 180nm, 200nm, 220nm, 250nm, 270nm, and 290nm, but are not limited to the above list; in the Mini LED chip, the reflective layer 320 can improve the light extraction efficiency, thereby increasing the luminous intensity of the chip.

[0051] The coating layer 330 includes one or more of Ti, Ni, and Pt; the thickness of the coating layer 330 is 100nm to 300nm, and exemplary thicknesses are 120nm, 150nm, 180nm, 200nm, 220nm, 250nm, 270nm, and 290nm, but are not limited to the above examples; the coating layer 330 can prevent the reflective layer 320 from being corroded by the external environment. At the same time, the coating layer 330 can also provide a certain mechanical strength to increase the durability of the pad 300.

[0052] The barrier layer 340 includes Ti; the thickness of the barrier layer 340 is 100nm to 500nm, and exemplary thicknesses are 120nm, 150nm, 180nm, 200nm, 220nm, 250nm, 270nm, 290nm, 300nm, 320nm, 350nm, 380nm, 400nm, 420nm, 450nm, 470nm, and 490nm, but are not limited to the above examples; the barrier layer 340 is a metal with a high melting point and a crystal structure different from that of metal Sn, and its purpose is to prevent Sn from further passing through the structure of the pad 300 when the pad 300 and the metal Sn are eutectic, thereby preventing the structure of the pad 300 from being destroyed and the electrode from falling off.

[0053] The magnetic attraction layer 350 includes Ni. The thickness of the magnetic attraction layer 350 is 300 nm to 5000 nm, and exemplary thicknesses are 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, 1300 nm, 1500 nm, 1800 nm, 2000 nm, 2500 nm, 3000 nm, 3500 nm, 4000 nm, and 4500 nm, but are not limited to the above examples.

[0054] It should be noted that the traditional thinning technology uses wax to fix the wafer, while the grinder in the present invention uses a magnetic disk 400, and generates a magnetic adsorption effect with the special magnetic absorption layer 350 in the wafer to fix the wafer. The magnetic absorption layer 350 is used to fix the wafer. The subsequent grinder uses the magnetic disk 400 to absorb the magnetic absorption layer 350 of the Mini LED chip wafer to fix the wafer, and the wafer is fixed and unfixed by powering on. In other words, the magnetic disk 400 can be controlled by electricity to determine whether it is magnetic, and then the wafer is fixed by generating a magnetic effect with the magnetic absorption layer 350 in the wafer pad 300. After fixation, the wafer can be thinned to any desired thickness through thinning and polishing, and can be thinned to a thickness of less than 80μm, which is not achievable with traditional thinning technology.

[0055] A protective layer is also provided on the magnetic attraction layer 350, and the protective layer includes Au; the thickness of the protective layer is 10nm to 50nm, and exemplary thicknesses are 15nm, 20nm, 25nm, 30nm, 35nm, and 40nm, but are not limited to the above enumeration; the protective layer is used to protect the magnetic attraction layer 350, and its thickness cannot be too thick, otherwise it will affect the magnetic effect of the magnetic attraction layer 350.

[0056] In some embodiments, the Mini LED chip wafer has an isolation groove design, which is formed by dry etching to remove the epitaxial layer to expose the substrate 100, and is used for cutting, thereby dividing the wafer into individual Mini LED chips.

[0057] (2) Figure 3 As shown, the Mini LED chip wafer is fixed on a grinder via a magnetic disk 400, and the substrate 100 of the Mini LED chip wafer is thinned to obtain a first wafer;

[0058] In some embodiments, fixing the Mini LED chip wafer on the grinder via a magnetic disk 400 includes: a magnetic disk 400 is provided on the grinder, and the magnetic disk 400 has magnetism after being powered on, so that the magnetic disk 400 and the Mini LED chip wafer are magnetically fixed.

[0059] In some embodiments, the thickness of the substrate 100 of the first wafer is ≤80 μm. Preferably, the thickness of the substrate 100 of the first wafer is ≤60 μm.

[0060] The grinder in the present invention uses a magnetic disk 400, and generates a magnetic adsorption effect with a special magnetic layer 350 in the wafer to fix the wafer. The magnetic layer 350 is used to fix the wafer. The subsequent grinder uses the magnetic disk 400 to adsorb the magnetic layer 350 of the Mini LED chip wafer to fix the wafer, and the wafer is fixed and unfixed by powering on. After fixing, the wafer is thinned to any desired thickness through thinning and polishing, and can be thinned to a thickness of less than 80μm, which is unattainable by traditional thinning technology.

[0061] (3) Figure 4 As shown, the temporary substrate 500 is bonded to the substrate 100 of the first wafer, and the magnetic disk 400 is separated from the first wafer to obtain a second wafer;

[0062] In some embodiments, the separation of the magnetic disk 400 and the first wafer is achieved by powering off the magnetic disk 400. After the thickness of the substrate 100 is reduced, the temporary base plate 500 is attached to the thinned wafer substrate 100. After the attachment, the magnetic disk 400 is powered off to make it lose its magnetism and not adsorb the wafer. Because of the temporary base plate 500, the wafer will not be warped.

[0063] In some embodiments, the temporary substrate 500 is a transparent substrate that can transmit UV light and infrared light; the thickness of the temporary substrate 500 is 20 μm to 100 μm, and exemplary thicknesses are 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, and 95 μm, but are not limited to the above. Due to the fixing effect of the temporary substrate 500, the thinned wafer will not warp.

[0064] In some embodiments, the temporary substrate 500 is bonded to the substrate 100 of the first wafer through a UV adhesive layer. The UV adhesive layer loses its adhesiveness under UV irradiation, which facilitates the subsequent peeling of the temporary substrate 500 and the Mini LED chip.

[0065] (4) cutting the second wafer to obtain a single Mini LED chip;

[0066] After thinning is completed, the next step is to cut the wafer. Figure 5As shown, the front side of the wafer is bonded to the blue film 600, and the sapphire substrate 100 of the wafer is cut using the laser hidden cutting technology, and the corresponding position is the isolation groove position. The wavelength used by the laser is an infrared wavelength, ranging from 900nm to 1600nm. The laser can pass through the temporary substrate 500 to produce a laser explosion point at the center thickness position of the substrate 100. After the hidden cutting is completed, the blue film side corresponding to the isolation groove position is then split to disconnect the substrate 100 at the laser explosion point. After the whole process is completed, the wafer cutting is completed.

[0067] During the entire cutting process, the temporary substrate 500 has a fixing function to prevent the wafer from being too warped and affecting the cutting yield. After the cutting is completed, the temporary substrate 100 is irradiated with UV light to complete the debonding of the temporary substrate 100, so that the UV adhesive layer loses its stickiness, thereby separating the substrate 100 and the temporary substrate 500. After the dissociation is completed, the wafer is turned over with a blue film to expose the front side of the wafer. After the film is turned over, the front side of the wafer, that is, the side with the pad 300, is exposed, and the spot measurement can be completed.

[0068] Correspondingly, the present invention also provides a Mini LED chip, which is manufactured by the Mini LED chip manufacturing method as described above.

[0069] To summarize, the preparation method of the Mini LED chip provided by the present invention, wherein the Mini LED chip wafer includes a substrate, a chip layer is sequentially arranged on the substrate, a soldering pad is arranged on the surface of the chip layer, and the soldering pad includes a magnetic attraction layer. The subsequent grinder uses a magnetic disk to absorb the magnetic attraction layer of the Mini LED chip wafer to fix the wafer, and the wafer is fixed and released by powering on. At the same time, a temporary substrate is used to fix the Mini LED chip wafer to avoid cracking and warping of the Mini LED chip wafer, reduce wafer fragments, and also avoid the problem of low cutting yield caused by wafer warping during cutting.

[0070] The present invention will be further described below with reference to embodiments.

[0071] Example 1

[0072] This embodiment provides a method for preparing a Mini LED chip, comprising the following steps:

[0073] A Mini LED chip wafer is provided, wherein the Mini LED chip wafer comprises a substrate, on which chip layers are sequentially arranged, a solder pad is arranged on a surface of the chip layer, and the solder pad comprises a magnetic attraction layer;

[0074] Fixing the Mini LED chip wafer on a grinder via a magnetic disk, and thinning the substrate of the Mini LED chip wafer to obtain a first wafer;

[0075] Laminating the temporary substrate and the substrate of the first wafer together, and separating the magnetic disk from the first wafer to obtain a second wafer;

[0076] The second wafer is cut to obtain a single Mini LED chip.

[0077] The pad includes a contact layer, a reflective layer, a coating layer, a barrier layer and a magnetic attraction layer connected in sequence from bottom to top; the contact layer includes Cr and Ni; the reflective layer includes Al; the coating layer includes Ti and Ni; the barrier layer includes Ti; and the magnetic attraction layer includes Ni.

[0078] The thickness of the substrate of the first wafer is 70 μm.

[0079] Example 2

[0080] This embodiment provides a method for preparing a Mini LED chip, comprising the following steps:

[0081] A Mini LED chip wafer is provided, wherein the Mini LED chip wafer comprises a substrate, on which chip layers are sequentially arranged, a solder pad is arranged on a surface of the chip layer, and the solder pad comprises a magnetic attraction layer;

[0082] Fixing the Mini LED chip wafer on a grinder via a magnetic disk, and thinning the substrate of the Mini LED chip wafer to obtain a first wafer;

[0083] Laminating the temporary substrate and the substrate of the first wafer together, and separating the magnetic disk from the first wafer to obtain a second wafer;

[0084] The second wafer is cut to obtain a single Mini LED chip.

[0085] The pad includes a contact layer, a reflective layer, a coating layer, a barrier layer and a magnetic attraction layer connected in sequence from bottom to top; the contact layer includes Cr and Ni; the reflective layer includes Al; the coating layer includes Ti and Ni; the barrier layer includes Ti; and the magnetic attraction layer includes Ni.

[0086] The thickness of the substrate of the first wafer is 60 μm.

[0087] Example 3

[0088] This embodiment provides a method for preparing a Mini LED chip, comprising the following steps:

[0089] A Mini LED chip wafer is provided, wherein the Mini LED chip wafer comprises a substrate, on which chip layers are sequentially arranged, a solder pad is arranged on a surface of the chip layer, and the solder pad comprises a magnetic attraction layer;

[0090] Fixing the Mini LED chip wafer on a grinder via a magnetic disk, and thinning the substrate of the Mini LED chip wafer to obtain a first wafer;

[0091] Laminating the temporary substrate and the substrate of the first wafer together, and separating the magnetic disk from the first wafer to obtain a second wafer;

[0092] The second wafer is cut to obtain a single Mini LED chip.

[0093] The pad includes a contact layer, a reflective layer, a coating layer, a barrier layer and a magnetic attraction layer connected in sequence from bottom to top; the contact layer includes Cr and Ni; the reflective layer includes Al; the coating layer includes Ti and Ni; the barrier layer includes Ti; and the magnetic attraction layer includes Ni.

[0094] The thickness of the substrate of the first wafer is 50 μm.

[0095] Comparative Example 1

[0096] This comparative example provides a method for preparing a Mini LED chip, comprising the following steps:

[0097] A Mini LED chip wafer is provided, wherein the Mini LED chip wafer comprises a substrate, chip layers are sequentially arranged on the substrate, and pads are arranged on surfaces of the chip layers;

[0098] Fixing the Mini LED chip wafer on a grinder by wax, and thinning the substrate of the Mini LED chip wafer to obtain a first wafer;

[0099] The first wafer is cut to obtain a single Mini LED chip.

[0100] The thickness of the substrate of the first wafer is 70 μm.

[0101] Comparative Example 2

[0102] This comparative example provides a method for preparing a Mini LED chip, comprising the following steps:

[0103] A Mini LED chip wafer is provided, wherein the Mini LED chip wafer comprises a substrate, chip layers are sequentially arranged on the substrate, and pads are arranged on surfaces of the chip layers;

[0104] Fixing the Mini LED chip wafer on a grinder by wax, and thinning the substrate of the Mini LED chip wafer to obtain a first wafer;

[0105] The first wafer is cut to obtain a single Mini LED chip.

[0106] The thickness of the substrate of the first wafer is 60 μm.

[0107] Comparative Example 3

[0108] This comparative example provides a method for preparing a Mini LED chip, comprising the following steps:

[0109] A Mini LED chip wafer is provided, wherein the Mini LED chip wafer comprises a substrate, chip layers are sequentially arranged on the substrate, and pads are arranged on surfaces of the chip layers;

[0110] Fixing the Mini LED chip wafer on a grinder by wax, and thinning the substrate of the Mini LED chip wafer to obtain a first wafer;

[0111] The first wafer is cut to obtain a single Mini LED chip.

[0112] The thickness of the substrate of the first wafer is 50 μm.

[0113] Examples 1 to 3 use the preparation method provided by the present invention to thin and cut the wafer, and Comparative Examples 1 to 3 use traditional thinning technology and cutting technology to thin and cut the wafer. The yield of each example and comparative example is calculated, and the specific results are shown in Table 1.

[0114] Table 1 Production yield results of Examples 1 to 3 and Comparative Examples 1 to 3

[0115]

[0116] It can be seen from the data in Table 1 that the preparation method of the Mini LED chip provided by the present invention, wherein the Mini LED chip wafer includes a substrate, a chip layer is sequentially arranged on the substrate, a soldering pad is arranged on the surface of the chip layer, and the soldering pad includes a magnetic attraction layer. The subsequent grinder uses a magnetic disk to absorb the magnetic attraction layer of the Mini LED chip wafer to fix the wafer, and the wafer is fixed and released by powering on. At the same time, the Mini LED chip wafer is fixed by a temporary substrate to avoid cracking and warping of the Mini LED chip wafer, reduce wafer fragments, and also avoid the problem of low cutting yield caused by wafer warping during cutting.

[0117] In the description of this specification, the description with reference to the terms "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiments or examples are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0118] The above is a preferred embodiment of the invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the invention. These improvements and modifications are also considered to be within the scope of protection of the invention.

Claims

1. A method for preparing a Mini LED chip, characterized in that: The following steps are involved: A Mini LED chip wafer is provided, wherein the Mini LED chip wafer comprises a substrate, on which chip layers are sequentially arranged, a solder pad is arranged on a surface of the chip layer, and the solder pad comprises a magnetic attraction layer; Fixing the Mini LED chip wafer on a grinder via a magnetic disk, and thinning the substrate of the Mini LED chip wafer to obtain a first wafer; Laminating the temporary substrate and the substrate of the first wafer together, and separating the magnetic disk from the first wafer to obtain a second wafer; The second wafer is cut to obtain a single Mini LED chip.

2. The method for preparing a Mini LED chip according to claim 1, wherein: The pad includes a contact layer, a reflective layer, a cladding layer, a barrier layer and a magnetic attraction layer connected in sequence from bottom to top; The contact layer includes one or more of Cr, Ni, and Ti; The reflective layer comprises Al; The coating layer includes one or more of Ti, Ni, and Pt; The barrier layer comprises Ti; The magnetic attraction layer includes Ni.

3. The method for preparing a Mini LED chip according to claim 2, wherein: A protective layer is also provided on the magnetic attraction layer, and the protective layer includes Au.

4. The method for preparing a Mini LED chip according to claim 3, wherein: The thickness of the contact layer is 3nm to 10nm; The thickness of the reflective layer is 100nm to 300nm; The coating layer has a thickness of 100 nm to 300 nm; The thickness of the barrier layer is 100nm to 500nm; The thickness of the magnetic attraction layer is 300nm-5000nm. The thickness of the protective layer is 10nm-50nm.

5. The method for preparing a Mini LED chip according to claim 1, wherein: Fixing the Mini LED chip wafer on the grinding machine through the magnetic plate includes: The grinding machine is provided with a magnetic disk, which becomes magnetic when powered on, so that the magnetic disk and the MiniLED chip wafer are magnetically fixed.

6. The method for preparing a Mini LED chip according to claim 1, wherein: The thickness of the substrate of the first wafer is ≤80 μm.

7. The method for preparing a Mini LED chip according to claim 1, wherein: The temporary substrate is a transparent substrate with a thickness of 20 μm to 100 μm.

8. The method for preparing a Mini LED chip according to claim 1, wherein: The temporary substrate is bonded to the substrate of the first wafer via a UV adhesive layer.

9. The method for preparing a Mini LED chip according to claim 1, wherein: The separation of the magnetic disk and the first wafer is achieved by powering off the magnetic disk.

10. A Mini LED chip, characterized in that: The Mini LED chip is manufactured by the method for manufacturing a Mini LED chip according to any one of claims 1 to 9.

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