Light emitting diode chip with improved adhesion and method of making the same

Abstract

The embodiment of the present disclosure provides a light emitting diode chip with improved adhesion and a manufacturing method thereof, and belongs to the technical field of semiconductors. The light emitting diode comprises a substrate, a light emitting structure, a first DBR layer and a second DBR layer. The substrate has opposite front and back surfaces. The light emitting structure is located on the front surface of the substrate. The first DBR layer is located on the back surface of the substrate. The first DBR layer comprises a plurality of first high refractive index layers and a plurality of first low refractive index layers which are alternately stacked. The first DBR layer has an array of recesses. The depth of the recesses is equal to the thickness of the first DBR layer. The second DBR layer is located in the recesses and is flush with the first DBR layer. The second DBR layer comprises a plurality of second high refractive index layers and a plurality of second low refractive index layers which are alternately stacked. The embodiment of the present disclosure can weaken the stress in the DBR layer, improve the adhesion of the DBR layer and improve the quality of the LED chip.

Description

Technical Field

[0001] This disclosure relates to the field of semiconductor technology, and in particular to a light-emitting diode chip with improved adhesion and a method for manufacturing the same. Background Technology

[0002] Light-emitting diodes (LEDs) are widely used in various light source fields such as backlighting, lighting, and landscaping due to their small size, long lifespan, rich and colorful colors, and low energy consumption.

[0003] In related technologies, an LED chip includes a substrate, a distributed Bragg reflection (DBR) layer, and a light-emitting structure. The light-emitting structure is located on the front side of the substrate, and the DBR layer is located on the back side of the substrate.

[0004] However, in the above structure, the DBR layer has poor adhesion due to the high stress of the material, making it prone to breakage and detachment, which affects the quality of the LED chip. Summary of the Invention

[0005] This disclosure provides a light-emitting diode chip with improved adhesion and a method for fabricating the same, which can reduce stress in the DBR layer, improve the adhesion of the DBR layer, and improve the quality of the LED chip. The technical solution is as follows:

[0006] On one hand, a light-emitting diode (LED) chip is provided, including a substrate, a light-emitting structure, a first distributed Bragg reflector layer, and a second distributed Bragg reflector layer. The substrate has a front side and a back side facing each other. The light-emitting structure is located on the front side of the substrate, and the first distributed Bragg reflector layer is located on the back side of the substrate. The first distributed Bragg reflector layer includes a plurality of alternatingly stacked first high-refractive-index layers and a plurality of alternating first low-refractive-index layers. The first distributed Bragg reflector layer has an array of grooves, the depth of which is equal to the thickness of the first distributed Bragg reflector layer. The second distributed Bragg reflector layer is located in the grooves and is flush with the first distributed Bragg reflector layer. The second distributed Bragg reflector layer includes a plurality of alternatingly stacked second high-refractive-index layers and a plurality of second low-refractive-index layers.

[0007] Optionally, the adhesion between the first distributed Bragg reflector layer and the substrate is greater than the adhesion between the second distributed Bragg reflector layer and the substrate.

[0008] Optionally, the total area of ​​the second distributed Bragg reflector is 20% to 80% of the sum of the areas of the first distributed Bragg reflector and the second distributed Bragg reflector.

[0009] Optionally, the refractive index difference between the second high refractive index layer and the second low refractive index layer is greater than the refractive index difference between the first high refractive index layer and the first low refractive index layer.

[0010] Optionally, the refractive index difference between the first high refractive index layer and the first low refractive index layer at a wavelength of 500 nm is 0.49 to 1.25, and the refractive index difference between the second high refractive index layer and the second low refractive index layer at a wavelength of 500 nm is 0.49 to 1.25.

[0011] Optionally, the material of the first high refractive index layer includes at least one of TiO2, ZnS, ZnSe, Ta2O5, HfO2, and ZrO2, and the material of the second high refractive index layer includes at least one of TiO2, ZnS, ZnSe, Ta2O5, HfO2, and ZrO2.

[0012] Optionally, the material of the first low refractive index layer includes at least one of SiO2, MgF2, AlF3, Na3AlF6, and BaF2, and the material of the second low refractive index layer includes at least one of SiO2, MgF2, AlF3, Na3AlF6, and BaF2.

[0013] Optionally, the side of the first distributed Bragg reflector layer closest to the substrate is the first low-refractive-index layer, and the side of the first distributed Bragg reflector layer furthest from the substrate is the first high-refractive-index layer; the side of the second distributed Bragg reflector layer closest to the substrate is the second low-refractive-index layer, and the side of the second distributed Bragg reflector layer furthest from the substrate is the second high-refractive-index layer.

[0014] Optionally, the groove is a cylindrical groove, a square prism groove, or a hexagonal prism groove.

[0015] On the other hand, a method for fabricating a light-emitting diode chip is provided, comprising: forming a light-emitting structure on the front side of a substrate; forming a first distributed Bragg reflector layer and a second distributed Bragg reflector layer on the back side of the substrate, wherein the first distributed Bragg reflector layer comprises a plurality of alternatingly stacked first high refractive index layers and a plurality of first low refractive index layers, the first distributed Bragg reflector layer having an array of grooves, the depth of the grooves being equal to the thickness of the first distributed Bragg reflector layer, the second distributed Bragg reflector layer being located in the grooves and flush with the first distributed Bragg reflector layer, the second distributed Bragg reflector layer comprising a plurality of alternatingly stacked second high refractive index layers and a plurality of second low refractive index layers.

[0016] The beneficial effects of the technical solutions provided in this disclosure are:

[0017] In this embodiment, the back side of the substrate has a first distributed Bragg reflector layer, which includes a plurality of alternating layers of first high refractive index and first low refractive index. The first distributed Bragg reflector layer has an array of grooves, the depth of which is equal to the thickness of the first distributed Bragg reflector layer. A second distributed Bragg reflector layer fills the grooves and is flush with the first distributed Bragg reflector layer. The second distributed Bragg reflector layer includes a plurality of alternating layers of second high refractive index and a plurality of second low refractive index. Since the DBR layer is divided into two parts, the areas of the two parts of the DBR layer are small, which can reduce the stress in the DBR layer, improve the adhesion of the DBR layer, reduce the probability of the DBR layer breaking and falling off, thereby improving the quality of the LED chip. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this disclosure, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of an LED chip in related technologies;

[0020] Figure 2 This is a schematic diagram of the structure of an LED chip provided in an embodiment of this disclosure;

[0021] Figure 3 This is a partial structural schematic diagram of an LED chip provided in an embodiment of this disclosure;

[0022] Figure 4 This is a bottom view of an LED chip provided in an embodiment of this disclosure;

[0023] Figure 5 This is a flowchart of a method for manufacturing an LED chip according to an embodiment of this disclosure;

[0024] Figure 6 This is a flowchart of another method for manufacturing an LED chip provided in this embodiment of the disclosure;

[0025] Figure 7 This is a flowchart of another LED chip manufacturing method provided in this disclosure embodiment. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this disclosure clearer, the embodiments of this disclosure will be described in further detail below with reference to the accompanying drawings.

[0027] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” “third,” and similar terms used in this patent application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an” or “a” and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “comprising” or “including” and similar terms mean that the elements or objects preceding “comprising” or “including” encompass the elements or objects listed following “comprising” or “including” and their equivalents, and do not exclude other elements or objects. The terms “connected” or “linked” and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms “upper,” “lower,” “left,” “right,” “top,” and “bottom,” etc., are used only to indicate relative positional relationships, and these relative positional relationships may change accordingly when the absolute position of the described objects changes.

[0028] Figure 1 This is a structural diagram of an LED chip in related technologies. For example... Figure 1 As shown, the LED chip includes a substrate 1, a light-emitting structure 2, and a distributed Bragg reflector layer 3. The light-emitting structure 2 is located on the front side of the substrate 1, and the distributed Bragg reflector layer 3 is located on the back side of the substrate 1. The distributed Bragg reflector layer 3 includes multiple alternating layers of high refractive index and low refractive index, wherein the high refractive index layers are generally TiO2 layers and the low refractive index layers are generally SiO2 layers.

[0029] The principle of DBR layer is that when light passes through film layers with different refractive indices, it will be reflected at the interface. The magnitude of reflectivity is related to the magnitude of the refractive index of the film layer. Therefore, by periodically stacking film layers with different refractive indices, when light passes through these film layers with different refractive indices, the light reflected back from each layer will undergo constructive interference due to the change in phase angle, and then combine with each other to obtain strongly reflected light.

[0030] like Figure 1 As shown, when the light emitted by the light-emitting structure 2 passes through the substrate 1 and is incident on the distributed Bragg reflector layer 3, the incident light with a large incident angle will be directly reflected back to the substrate 1. The incident light with a small incident angle will be refracted into the distributed Bragg reflector layer 3, and after multiple superposition interferences in the distributed Bragg reflector layer 3, it will be reflected back to the substrate 1. During this process, the distributed Bragg reflector layer 3 will absorb some of the incident light with a small incident angle, resulting in a loss of reflectivity and affecting the luminous efficiency of the LED chip.

[0031] To improve the luminous efficiency of LED chips, related technologies may modify the material of the distributed Bragg reflector layer 3 (DBR). However, the high stress in the material of the full-area DBR layer can lead to poor adhesion, making it prone to breakage and detachment, thus affecting the quality of the LED chip. For example, replacing the low-refractive-index layer of the DBR layer 3 with MgF2 may result in a higher reflectivity for the DBR layer formed by alternating layers of TiO2 and MgF2. However, when the full-area DBR layer uses alternating layers of TiO2 and MgF2, the high stress in the MgF2 material within the DBR layer leads to poor adhesion of the DBR layer 3, making it prone to breakage and detachment, thus affecting the quality of the LED chip.

[0032] Figure 2 This is a schematic diagram of the structure of an LED chip provided in an embodiment of this disclosure. Figure 2 As shown, the LED chip includes a substrate 10, a light-emitting structure 20, a first distributed Bragg reflector layer 30, and a second distributed Bragg reflector layer 40. The substrate 10 has a front side and a back side, with the light-emitting structure 20 located on the front side of the substrate 10 and the first distributed Bragg reflector layer 30 located on the back side of the substrate 10.

[0033] The first distributed Bragg reflector layer 30 includes a plurality of alternating layers of first high refractive index layers 31 and a plurality of alternating layers of first low refractive index layers 32. The first distributed Bragg reflector layer 30 has arrayed grooves 33, the depth of which is equal to the thickness of the first distributed Bragg reflector layer 30, i.e., the grooves 33 penetrate the first distributed Bragg reflector layer 30 to the back surface of the substrate 10. The second distributed Bragg reflector layer 40 is located within the grooves 33 and is flush with the first distributed Bragg reflector layer 30. The second distributed Bragg reflector layer 40 includes a plurality of alternating layers of second high refractive index layers 41 and a plurality of alternating layers of second low refractive index layers 42.

[0034] In this embodiment, since the DBR layer is divided into two parts, and the area of ​​each part of the DBR layer is small, the stress in the DBR layer can be reduced, the adhesion of the DBR layer can be improved, and the probability of the DBR layer breaking and falling off can be reduced, thereby improving the quality of the LED chip.

[0035] Optionally, substrate 10 is a sapphire substrate. Sapphire substrates are transparent substrates with good light transmittance, and they also have high mechanical strength and are easy to handle and clean. In some examples, substrate 10 may also be a SiC substrate, and this disclosure does not limit this.

[0036] Optionally, the light-emitting structure 20 includes an N-type layer 21, a multiple quantum well layer 22, and a P-type layer 23. The N-type layer 21 may be an N-type GaN layer, the multiple quantum well layer 22 may include multiple periodically alternating InGaN well layers and GaN barrier layers, and the P-type layer 23 may be a P-type GaN layer. The light emitted by the light-emitting structure 20 may originate from the multiple quantum well layer 22.

[0037] Optionally, the first distributed Bragg reflector 30 includes 20 to 30 pairs of alternating layers of a first high refractive index layer 31 and a first low refractive index layer 32, and the second distributed Bragg reflector 40 includes 20 to 30 pairs of alternating layers of a second high refractive index layer 41 and a second low refractive index layer 42.

[0038] In a DBR layer, if the number of alternating high- and low-refractive-index layers is too small, the reflectivity of the DBR layer will be low, affecting the luminous efficiency of the LED chip. When the number of alternating layers of the first high-refractive-index layer 31 and the first low-refractive-index layer 32, as well as the number of alternating layers of the second high-refractive-index layer 41 and the second low-refractive-index layer 42, is within the above range, the reflectivity of the first distributed Bragg reflector layer 30 and the second reflective layer 40 can be increased, thereby improving the luminous efficiency of the LED chip.

[0039] For example, the first high refractive index layer 31 and the first low refractive index layer 32 can be stacked alternately in 20 pairs. The second high refractive index layer 41 and the second low refractive index layer 42 can be stacked alternately in 20 pairs.

[0040] Optionally, the optical thicknesses of the first high-refractive-index layer 31, the first low-refractive-index layer 32, the second high-refractive-index layer 41, and the second low-refractive-index layer 42 are all one-quarter of the central reflection wavelength. Here, the optical thickness is the product of the material's geometric thickness and its refractive index.

[0041] When the optical thickness of the first high refractive index layer 31, the first low refractive index layer 32, the second high refractive index layer 41, and the second low refractive index layer 42 is one-quarter of the central reflection wavelength, the resulting DBR layer, namely the first distributed Bragg reflector layer 30 and the second distributed Bragg reflector layer 40, has a higher reflectivity to light.

[0042] Figure 3 This is a partial structural schematic diagram of an LED chip provided in an embodiment of this disclosure. For example... Figure 3 As shown, the LED chip has a light-emitting structure 20 on the front side of the substrate 10, and a first distributed Bragg reflector layer 30 located on the back side of the substrate 10. The first distributed Bragg reflector layer 30 has an array of grooves 33 arranged in the array. The depth of the grooves 33 is equal to the thickness of the first distributed Bragg reflector layer 30, that is, the grooves 33 penetrate through the first distributed Bragg reflector layer 30 to the back side of the substrate 10.

[0043] Figure 4 This is a bottom view of an LED chip provided in an embodiment of this disclosure. Figure 4 As shown, the second distributed Bragg reflector layer 40 is located in the arrayed groove 33 and is flush with the first distributed Bragg reflector layer 30. The groove 33 can be an arrayed cylindrical groove. Figure 4 The array consists of 5 rows and 6 columns of grooves 33, with the center distance between adjacent grooves 33 being equal. Of course, other array arrangements can also be used, and this disclosure does not limit this.

[0044] Optionally, the groove 33 can be a cylindrical groove, a square prism groove, or a hexagonal prism groove. The groove 33 being configured in the above shapes is beneficial for LED chip manufacturing, and also helps to reduce stress in the DBR layer, improve the adhesion of the DBR layer, reduce the probability of DBR layer breakage and detachment, and improve the quality of the LED chip.

[0045] As an example, in this embodiment, the groove 33 is a cylindrical groove. It should be noted that the shape of the groove 33 includes, but is not limited to, the above-mentioned types, and can also be any other columnar or polygonal groove, etc., which is not limited in this disclosure.

[0046] Optionally, the adhesion between the first distributed Bragg reflector layer 30 and the substrate 10 is greater than the adhesion between the second distributed Bragg reflector layer 40 and the substrate 10. This results in better adhesion between the DBR layer and the substrate 10, reducing the likelihood of the DBR layer breaking and detaching, and improving the quality of the LED chip.

[0047] In some examples, the first distributed Bragg reflector 30 and the second distributed Bragg reflector 40 are made of the same material. In other examples, the first distributed Bragg reflector 30 and the second distributed Bragg reflector 40 are made of different materials.

[0048] Optionally, the total area of ​​the second distributed Bragg reflector 40 is 20% to 80% of the sum of the areas of the first distributed Bragg reflector 30 and the second distributed Bragg reflector 40.

[0049] The sum of the areas of the first distributed Bragg reflector layer 30 and the second distributed Bragg reflector layer 40 is the total area of ​​the DBR layer. When the area of ​​the second distributed Bragg reflector layer 40 is too small or too large relative to the total area of ​​the DBR layer, the division of the two parts of the DBR layer is not uniform enough. This may result in significant stress remaining in either the first or second distributed Bragg reflector layer 30, failing to improve the adhesion of the DBR layer. Within this range, the total area of ​​the second distributed Bragg reflector layer 40 can better reduce stress in the DBR layer, improve its adhesion, and ultimately enhance the quality of the LED chip.

[0050] In some examples, the total area of ​​the second distributed Bragg reflector 40 is 40% to 60% of the sum of the areas of the first distributed Bragg reflector 30 and the second distributed Bragg reflector 40.

[0051] Optionally, the material of the first high refractive index layer 31 includes at least one of TiO2, ZnS, ZnSe, Ta2O5, HfO2, and ZrO2, and the material of the second high refractive index layer 41 includes at least one of TiO2, ZnS, ZnSe, Ta2O5, HfO2, and ZrO2. These materials have relatively high refractive indices, good stability, and low absorption coefficients, making them suitable as high refractive index layers in a DBR (Digital Backdrop Injection) layer for reflection.

[0052] Optionally, the material of the first low-refractive-index layer 32 includes at least one of SiO2, MgF2, AlF3, Na3AlF6, and BaF2, and the material of the second low-refractive-index layer 42 includes at least one of SiO2, MgF2, AlF3, Na3AlF6, and BaF2. These materials have low refractive indices, good stability, and low absorption coefficients, making them suitable as low-refractive-index layers in a DBR (Digital-Reflective Base) layer for reflection.

[0053] In some examples, substrate 10 is a sapphire substrate. The first distributed Bragg layer 30 and the second distributed Bragg layer 40 are made of different materials. The first high-refractive-index layer 31 is made of TiO2, the first low-refractive-index layer 32 is made of SiO2, the second high-refractive-index layer 41 is made of TiO2, and the second low-refractive-index layer 42 is made of MgF2. The number of alternating stacked pairs of the first high-refractive-index layer 31 and the first low-refractive-index layer 32 is 24, and the number of alternating stacked pairs of the second high-refractive-index layer 41 and the second low-refractive-index layer 42 is 20 to 28. The thickness of the first distributed Bragg layer is approximately 4.5 μm. The total area of ​​the DBR layer is approximately 5.8 × 10⁻⁶. 5 μm 2 That is, the sum of the areas of the first distributed Bragg reflector 30 and the second distributed Bragg reflector 40 is approximately 5.8 * 10. 5 μm 2The first distributed Bragg reflector layer 30 has 5 rows and 9 columns of grooves 33 arranged in an array. The center distance between adjacent grooves 33 is equal. The grooves 33 are cylindrical, and each groove 33 has a diameter of 90 μm. The second distributed Bragg reflector layer 40 is located in the grooves 33 and is flush with the first distributed Bragg reflector layer. The total area of ​​the second distributed Bragg reflector layer 40 is approximately 49% of the sum of the areas of the first distributed Bragg reflector layer 30 and the second distributed Bragg reflector layer 40. Compared with LED chips that use the same logarithmic alternating stacked TiO2 and MgF2 layers in the DBR layer with the same total area, the LED chip breakage and detachment rate in this embodiment is reduced by approximately 90%.

[0054] In some examples, substrate 10 is a sapphire substrate. The first distributed Bragg layer 30 and the second distributed Bragg layer 40 are made of the same material. The first high-refractive-index layer 31 and the second high-refractive-index layer 41 are both made of TiO2, and the first low-refractive-index layer 32 and the second low-refractive-index layer 42 are both made of MgF2. The number of alternating stacked pairs of the first high-refractive-index layer 31 and the first low-refractive-index layer 32 is the same, ranging from 20 to 28 pairs. The thickness of the first distributed Bragg layer is approximately 4.5 μm. The total area of ​​the DBR layer is approximately 5.8 × 10⁻⁶. 5 μm 2 That is, the sum of the areas of the first distributed Bragg reflector 30 and the second distributed Bragg reflector 40 is approximately 5.8 * 10. 5 μm 2 The first distributed Bragg reflector layer 30 has 5 rows and 9 columns of grooves 33 arranged in an array. The center distance between adjacent grooves 33 is equal. The grooves 33 are cylindrical, and each groove 33 has a diameter of 90 μm. The second distributed Bragg reflector layer 40 is located in the grooves 33. The total area of ​​the second distributed Bragg reflector layer 40 is approximately 49% of the sum of the areas of the first distributed Bragg reflector layer 30 and the second distributed Bragg reflector layer 40. Compared with LED chips with the same total area of ​​DBR layer and using the same logarithmic alternating stacked TiO2 and MgF2 layers, the LED chip breakage and detachment rate in this embodiment is reduced by approximately 90%.

[0055] Optionally, the refractive index difference between the second high-refractive-index layer 41 and the second low-refractive-index layer 42 is greater than the refractive index difference between the first high-refractive-index layer 31 and the first low-refractive-index layer 32. Since the greater the refractive index difference between the high and low refractive-index layers in the DBR layer, the higher the reflectivity of the DBR layer, the second distributed Bragg reflector layer 40 can increase the reflectivity of light, thereby reducing the absorption of light by the DBR layer and improving the luminous efficiency of the LED chip.

[0056] Optionally, the refractive index of the first high-refractive-index layer 31 is less than or equal to the refractive index of the second high-refractive-index layer 41, and the refractive index of the first low-refractive-index layer 32 is greater than the refractive index of the second low-refractive-index layer 42. This ensures that the refractive index difference between the second high-refractive-index layer 41 and the second low-refractive-index layer 42 is greater than the refractive index difference between the first high-refractive-index layer 31 and the first low-refractive-index layer 32, allowing the second distributed Bragg reflector layer 40 to increase the reflectivity of light, thereby reducing the absorption of light by the DBR layer and improving the luminous efficiency of the LED chip.

[0057] Optionally, the refractive index difference between the first high-refractive-index layer 31 and the first low-refractive-index layer 32 at a wavelength of 500 nm is 0.49 to 1.25, and the refractive index difference between the second high-refractive-index layer 41 and the second low-refractive-index layer 42 at a wavelength of 500 nm is also 0.49 to 1.25. This allows for higher reflectivity of the two distributed Bragg reflector layers, ensuring the luminous efficiency of the LED chip.

[0058] When the high-refractive-index layer is made of HfO2, with a refractive index of 1.95 at 500 nm, and the low-refractive-index layer is made of SiO2, with a refractive index of 1.46 at 500 nm, the refractive index difference between the high-refractive-index and low-refractive-index layers is 0.49. When the high-refractive-index layer is made of ZnSe, with a refractive index of 2.58 at 500 nm, and the low-refractive-index layer is made of Na3AlF6, with a refractive index of 1.33 at 500 nm, the refractive index difference between the high-refractive-index and low-refractive-index layers is 1.25.

[0059] For example, the materials of the first high refractive index layer 31 and the second high refractive index layer 41 can both be TiO2, which has a refractive index of 2.5 at a wavelength of 500 nm; the material of the first low refractive index layer 32 can be SiO2, which has a refractive index of 1.46 at a wavelength of 500 nm; and the material of the second low refractive index layer 42 can be MgF2, which has a refractive index of 1.38 at a wavelength of 500 nm. Thus, the refractive index of the first high refractive index layer 31 is equal to the refractive index of the second high refractive index layer 41, and the refractive index of the first low refractive index layer 32 is greater than the refractive index of the second low refractive index layer 42. The refractive index difference between the first high refractive index layer 31 and the first low refractive index layer 32 at a wavelength of 500 nm is 1.04, and the refractive index difference between the second high refractive index layer 41 and the second low refractive index layer 42 at a wavelength of 500 nm is 1.12. The refractive index difference between the second high refractive index layer 41 and the second low refractive index layer 42 is greater than that between the first high refractive index layer 31 and the first low refractive index layer 32. Therefore, the second distributed Bragg reflector layer 30 has a higher reflectivity, which can increase the reflectivity of light and improve the luminous efficiency of the LED chip.

[0060] Optionally, the side of the first distributed Bragg reflector layer 30 closest to the substrate 10 is a first low refractive index layer 32, and the side of the first distributed Bragg reflector layer 30 furthest from the substrate 10 is a first high refractive index layer 31.

[0061] The side of the first distributed Bragg reflector layer 30 closest to the substrate 10 is designated as the first low-refractive-index layer 32. In other words, the interface between the first distributed Bragg reflector layer 30 and the substrate 10 is also the interface between the first low-refractive-index layer 32 and the substrate 10. The refractive index of the first low-refractive-index layer 32 is significantly different from that of the substrate 10, and the refractive index of the first low-refractive-index layer 32 is less than that of the substrate 10. This facilitates total internal reflection when light travels from the substrate 10 to the first low-refractive-index layer 32, thus improving the reflectivity. Total internal reflection occurs when light travels from a higher refractive-index layer to a lower refractive-index layer, and all incident light is reflected without refracting into the lower refractive-index layer. When total internal reflection occurs, the reflectivity is equal to 1.

[0062] Optionally, the side of the second distributed Bragg reflector layer 40 closest to the substrate 10 is a second low-refractive-index layer 42, and the side of the second distributed Bragg reflector layer 40 furthest from the substrate 10 is a second high-refractive-index layer 41.

[0063] The side of the second distributed Bragg reflector layer 40 closest to the substrate 10 is designated as the second low-refractive-index layer 42. In other words, the interface between the second distributed Bragg reflector layer 40 and the substrate 10 is also the interface between the second low-refractive-index layer 42 and the substrate 10. The refractive index of the second low-refractive-index layer 42 is significantly lower than that of the substrate 10, resulting in total internal reflection when light travels from the substrate 10 to the second low-refractive-index layer 42, thus improving the reflectivity of light.

[0064] In some examples, substrate 10 is a sapphire substrate with a refractive index of 1.76 at a wavelength of 500 nm, the first low-refractive-index layer 32 is SiO2 with a refractive index of 1.46 at a wavelength of 500 nm, and the second low-refractive-index layer is MgF2 with a refractive index of 1.38 at a wavelength of 500 nm. When light is incident from substrate 10 to the first low-refractive-index layer 32, the critical angle is approximately 56°, while when light is incident from substrate 10 to the second low-refractive-index layer 42, the critical angle is approximately 51.6°. The critical angle is the minimum angle of incidence required for total internal reflection to occur; total internal reflection occurs when the angle of incidence is greater than the critical angle. Therefore, the critical angle when light is incident from the substrate 10 to the second low refractive index layer 42 is smaller than the critical angle when light is incident from the substrate 10 to the first low refractive index layer 32. In other words, the second distributed Bragg reflector layer 40 can cause more incident light with small incident angles to undergo total internal reflection, increasing the reflectivity of incident light with small incident angles, thereby reducing the absorption of light by the DBR layer and improving the luminous efficiency of the LED chip.

[0065] Figure 5 This is a flowchart illustrating a method for manufacturing an LED chip according to an embodiment of this disclosure. Figure 5 As shown, the manufacturing method includes:

[0066] Step S101: Form a light-emitting structure on the front side of the substrate.

[0067] Step S102: Form a first distributed Bragg reflection layer and a second distributed Bragg reflection layer on the back side of the substrate.

[0068] The first distributed Bragg reflector layer includes multiple alternating layers of first high refractive index and multiple layers of first low refractive index. The first distributed Bragg reflector layer has an array of grooves, the depth of which is equal to the thickness of the first distributed Bragg reflector layer. The second distributed Bragg reflector layer is located in the grooves and is flush with the first distributed Bragg reflector layer. The second distributed Bragg reflector layer includes multiple alternating layers of second high refractive index and multiple layers of second low refractive index.

[0069] In this embodiment, the back side of the substrate has a first distributed Bragg reflector layer, which includes a plurality of alternating layers of first high refractive index and first low refractive index. The first distributed Bragg reflector layer has an array of grooves, the depth of which is equal to the thickness of the first distributed Bragg reflector layer. A second distributed Bragg reflector layer fills the grooves and is flush with the first distributed Bragg reflector layer. The second distributed Bragg reflector layer includes a plurality of alternating layers of second high refractive index and a plurality of second low refractive index. Since the DBR layer is divided into two parts, the areas of the two parts of the DBR layer are small, which can reduce the stress in the DBR layer, improve the adhesion of the DBR layer, reduce the probability of the DBR layer breaking and falling off, thereby improving the quality of the LED chip.

[0070] Figure 6 This is a flowchart illustrating another method for manufacturing an LED chip according to an embodiment of this disclosure. Figure 6 As shown, the manufacturing method includes:

[0071] Step S201: Provide a substrate.

[0072] Alternatively, the substrate can be a sapphire substrate.

[0073] In step S201, the sapphire substrate can be pretreated by placing it in a metal-organic chemical vapor deposition (MOCVD) reaction chamber and baking it for 12 to 18 minutes.

[0074] Step S202: Form a light-emitting structure on the front side of the substrate.

[0075] Optionally, the light-emitting structure includes an N-type layer, a multiple quantum well layer, and a P-type layer.

[0076] Optionally, step S202 may include the following steps:

[0077] The first step is to form an N-type layer on the front side of the substrate.

[0078] For example, the N-type layer can be an N-type GaN layer. The growth temperature of the N-type layer can be from 1000°C to 1200°C, and the growth pressure can be from 50 Torr to 200 Torr.

[0079] In some examples, a u-type GaN layer may be formed on the substrate before forming the N-type layer. Alternatively, a buffer layer, such as an AlN buffer layer, may be formed on the substrate 10 before forming the u-type GaN layer.

[0080] The second step is to form a multi-quantum-well layer on the N-type layer.

[0081] Exemplarily, a multi-quantum-well layer may include multiple alternating InGaN well layers and GaN barrier layers. The number of alternating stacked quantum well layers and quantum barrier layers can be 3 to 8. As an example, in an embodiment of this disclosure, the number of alternating stacked quantum well layers and quantum barrier layers is 5. The growth temperature of the quantum well layer can be 760°C to 780°C, and the growth pressure can be 200 Torr; the growth temperature of the quantum barrier layer can be 860°C to 890°C, and the growth pressure can be 200 Torr.

[0082] The third step is to form a P-type layer on the multi-quantum-well layer.

[0083] For example, the P-type layer can be a P-type GaN layer. The growth temperature of the P-type layer can be from 850°C to 1050°C, and the growth pressure can be from 100 Torr to 600 Torr.

[0084] Step S203: Deposit a first distributed Bragg reflector layer on the back side of the substrate.

[0085] The first distributed Bragg reflector layer comprises multiple alternating layers of first high refractive index and multiple layers of first low refractive index.

[0086] Alternatively, the substrate can be placed in an electron beam evaporation furnace to deposit a first distributed Bragg reflector layer.

[0087] Optionally, the materials of the first high-refractive-index layer and the first low-refractive-index layer, the thicknesses of the first high-refractive-index layer and the first low-refractive-index layer, and the logarithm of the alternating stacking of the first high-refractive-index layer and the first low-refractive-index layer are described in [reference]. Figure 2 Related embodiments are omitted in detail here.

[0088] Optionally, in step S203, a first low-refractive-index layer needs to be deposited first, so that the side of the first distributed Bragg reflector layer closest to the substrate is the first low-refractive-index layer, and it is also necessary to ensure that the last deposited layer is the first high-refractive-index layer, so that the side of the first distributed Bragg reflector layer furthest from the substrate is the first high-refractive-index layer.

[0089] Step S204: Apply a protective agent to the front side of the chip.

[0090] Alternatively, the protective agent can be a thick, easily removable curing protective agent. The protective agent is used to protect the front side of the chip from photolithography damage during patterning. For example, the protective agent can be photoresist.

[0091] Step S205: Create a photolithographic pattern on the first distributed Bragg reflector layer.

[0092] Optionally, photoresist can be coated on the first distributed Bragg reflector layer, and the photoresist can be exposed and developed to form a patterned photoresist mask layer. The pattern of the photoresist removal area can be a circular array, a quadrilateral array, or a hexagonal array.

[0093] Step S206: Etch the first distributed Bragg reflector layer to form an array of grooves.

[0094] The first distributed Bragg reflector layer is etched using methods such as inductively coupled plasma (ICP) etching to form an array of grooves in the first distributed Bragg reflector layer. The depth of the grooves is equal to the thickness of the first distributed Bragg reflector layer.

[0095] Optionally, the groove can be a cylindrical groove, a square prism groove, or a hexagonal prism groove.

[0096] For example, the grooves can be cylindrical grooves arranged in an array, with the center of adjacent grooves being equidistant.

[0097] Step S207: Evaporate the second distributed Bragg reflector layer.

[0098] The second distributed Bragg reflector is located in the groove and is flush with the first distributed Bragg reflector. The second distributed Bragg reflector comprises multiple alternating layers of second high refractive index layers and multiple layers of second low refractive index layers.

[0099] Alternatively, the substrate can be placed in an electron beam evaporation furnace to deposit a second distributed Bragg reflector layer, and then the photoresist can be removed to complete the fabrication of the LED chip.

[0100] Optionally, the total area of ​​the second distributed Bragg reflector is 20% to 80% of the sum of the areas of the first and second distributed Bragg reflectors.

[0101] Optionally, the materials of the second high-refractive-index layer and the second low-refractive-index layer, the thicknesses of the second high-refractive-index layer and the second low-refractive-index layer, the logarithm of the alternating stacking of the second high-refractive-index layer and the second low-refractive-index layer, and the proportion of the total area of ​​the second distributed Bragg reflector layer to the total area of ​​the DBR layer are specified in [reference needed]. Figure 2 Related embodiments are omitted in detail here. For the relationship between the refractive indices of each refractive index layer, the range of refractive index differences, and the magnitude of the refractive index differences, please refer to [reference needed]. Figure 2 Related embodiments are omitted in detail here.

[0102] Optionally, in step S207, a second low-refractive-index layer needs to be deposited first, so that the side of the second distributed Bragg reflector layer closest to the substrate is the second low-refractive-index layer, and it is also necessary to ensure that the last deposited layer is the second high-refractive-index layer, so that the side of the second distributed Bragg reflector layer furthest from the substrate is the second high-refractive-index layer.

[0103] In other embodiments, the order of deposition of the first and second distributed Bragg reflector layers can be changed. Steps S203 to S207 can also involve first depositing the second distributed Bragg reflector layer on the back side of the substrate; applying a protective agent to the front side of the chip; creating a photolithographic pattern on the second distributed Bragg reflector layer, where the pattern of the photoresist retention area can be a circular array, a quadrilateral array, or a hexagonal array; etching the second distributed Bragg reflector layer to form an array of columnar protrusions; and then depositing the first distributed Bragg reflector layer. The second distributed Bragg reflector layer is flush with the first distributed Bragg reflector layer. The second distributed Bragg reflector layer consists of an array of columnar protrusions, and the shape of these columnar protrusions is the same as the grooves in steps S205 to S206, meaning it is equivalent to the first distributed Bragg reflector layer having an array of grooves. The depth of the grooves is equal to the thickness of the first distributed Bragg reflector layer, and the second distributed Bragg reflector layer is located within the grooves and flush with the first distributed Bragg reflector layer.

[0104] Figure 7 This is a flowchart illustrating another method for manufacturing an LED chip according to an embodiment of this disclosure. Figure 7 As shown, the manufacturing method includes:

[0105] Step S301: Provide a substrate.

[0106] Step S302: Form a light-emitting structure on the front side of the substrate.

[0107] Steps S301 to S302 can be combined with Figure 6 Steps S201 to S202 in the relevant embodiments are the same, and detailed descriptions are omitted here.

[0108] Step S303: Apply a protective agent to the front side of the chip.

[0109] Alternatively, the protective agent can be a thick, easily removable curing protective agent. The protective agent is used to protect the front side of the chip from photolithography damage during patterning. For example, the protective agent can be photoresist.

[0110] Step S304: Create a photolithographic pattern on the back side of the substrate.

[0111] Optionally, photoresist can be coated on the back side of the substrate, and the photoresist can be exposed and developed to form a patterned photoresist mask layer. The pattern of the photoresist retention area can be a circular array, a quadrilateral array, or a hexagonal array.

[0112] Step S305: Deposit a first distributed Bragg reflector layer on the back side of the substrate.

[0113] The first distributed Bragg reflector layer comprises alternating layers of first high refractive index layers and multiple layers of first low refractive index layers. The first distributed Bragg reflector layer has arrayed grooves, the depth of which is equal to the thickness of the first distributed Bragg reflector layer.

[0114] Alternatively, the substrate can be placed in an electron beam evaporation furnace to deposit a first distributed Bragg reflector layer.

[0115] Optionally, the materials of the first high-refractive-index layer and the first low-refractive-index layer, the thicknesses of the first high-refractive-index layer and the first low-refractive-index layer, and the logarithm of the alternating stacking of the first high-refractive-index layer and the first low-refractive-index layer are described in [reference]. Figure 2 Related embodiments are omitted in detail here.

[0116] Optionally, in step S305, a first low-refractive-index layer needs to be deposited first, so that the side of the first distributed Bragg reflector layer closest to the substrate is the first low-refractive-index layer, and it is also necessary to ensure that the last deposited layer is the first high-refractive-index layer, so that the side of the first distributed Bragg reflector layer furthest from the substrate is the first high-refractive-index layer.

[0117] After completing step S305, the photoresist needs to be removed.

[0118] Step S306: Create a photolithographic pattern on the first distributed Bragg reflector layer.

[0119] Optionally, photoresist can be coated on the first distributed Bragg reflector layer, and the photoresist can be exposed and developed to form a patterned photoresist mask layer, where the photoresist removal area coincides with the groove pattern arranged in an array in the first distributed Bragg reflector layer.

[0120] Step S307: Evaporate the second distributed Bragg reflector layer.

[0121] The second distributed Bragg reflector is located in the groove and is flush with the first distributed Bragg reflector. The second distributed Bragg reflector comprises multiple alternating layers of second high refractive index layers and multiple layers of second low refractive index layers.

[0122] Alternatively, the substrate can be placed in an electron beam evaporation furnace to deposit a second distributed Bragg reflector layer, and then the photoresist can be removed to complete the fabrication of the LED chip.

[0123] Optionally, the materials of the second high-refractive-index layer and the second low-refractive-index layer, the thicknesses of the second high-refractive-index layer and the second low-refractive-index layer, the logarithm of the alternating stacking of the second high-refractive-index layer and the second low-refractive-index layer, and the proportion of the total area of ​​the second distributed Bragg reflector layer to the total area of ​​the DBR layer are specified in [reference needed]. Figure 2 Related embodiments are omitted in detail here. For the relationship between the refractive indices of each refractive index layer, the range of refractive index differences, and the magnitude of the refractive index differences, please refer to [reference needed]. Figure 2 Related embodiments are omitted in detail here.

[0124] Optionally, in step S307, a second low-refractive-index layer needs to be deposited first, so that the side of the second distributed Bragg reflector layer closest to the substrate is the second low-refractive-index layer, and it is also necessary to ensure that the last deposited layer is the second high-refractive-index layer, so that the side of the second distributed Bragg reflector layer furthest from the substrate is the second high-refractive-index layer.

[0125] This embodiment and Figure 6 The difference between the related embodiments is that in this embodiment, the photolithographic pattern is made first and then the first distributed Bragg reflection layer is deposited by vapor deposition. There is no need to etch the excess part of the first distributed Bragg reflection layer, so that the patterned first distributed Bragg reflection layer with arrayed grooves can be directly formed.

[0126] In other embodiments, the order of deposition of the first and second distributed Bragg reflector layers can be changed. Steps S304 to S307 can also involve first creating a photolithographic pattern on the back side of the substrate, where the pattern of the photoresist removal area can be a circular array, a quadrilateral array, or a hexagonal array; then depositing the second distributed Bragg reflector layer on the back side of the substrate to form an array of columnar protrusions; creating a photolithographic pattern on the second distributed Bragg reflector layer, where the photoresist retention area overlaps with the pattern of the second distributed Bragg reflector layer; and finally depositing the first distributed Bragg reflector layer. The second distributed Bragg reflector layer is flush with the first distributed Bragg reflector layer and consists of an array of columnar protrusions. The shape of these columnar protrusions is the same as the grooves in steps S304 to S305, meaning it is equivalent to the first distributed Bragg reflector layer having an array of grooves. The depth of the grooves is equal to the thickness of the first distributed Bragg reflector layer, and the second distributed Bragg reflector layer is located within the grooves and flush with the first distributed Bragg reflector layer.

[0127] The above description is not intended to limit this disclosure in any way. Although this disclosure has been disclosed above through embodiments, it is not intended to limit this disclosure. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the technical solution of this disclosure. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of this disclosure without departing from the content of the technical solution of this disclosure shall still fall within the scope of the technical solution of this disclosure.

Claims

1. A light-emitting diode chip, characterized in that, It includes a substrate, a light-emitting structure, a first distributed Bragg reflector layer, and a second distributed Bragg reflector layer. The substrate has a front side and a back side, and the light-emitting structure is located on the front side of the substrate. The first distributed Bragg reflector layer is located on the back side of the substrate. The first distributed Bragg reflector layer includes a plurality of alternating layers of first high refractive index and a plurality of layers of first low refractive index. The first distributed Bragg reflector layer has an array of grooves, the depth of which is equal to the thickness of the first distributed Bragg reflector layer. The second distributed Bragg reflector is located in the groove and is flush with the first distributed Bragg reflector. The second distributed Bragg reflector includes a plurality of alternately stacked second high refractive index layers and a plurality of second low refractive index layers.

2. The light-emitting diode chip according to claim 1, characterized in that, The adhesion between the first distributed Bragg reflector layer and the substrate is greater than the adhesion between the second distributed Bragg reflector layer and the substrate.

3. The light-emitting diode chip according to claim 2, characterized in that, The total area of ​​the second distributed Bragg reflector is 20% to 80% of the sum of the areas of the first distributed Bragg reflector and the second distributed Bragg reflector.

4. The light-emitting diode chip according to claim 2, characterized in that, The refractive index difference between the second high refractive index layer and the second low refractive index layer is greater than the refractive index difference between the first high refractive index layer and the first low refractive index layer.

5. The light-emitting diode chip according to claim 4, characterized in that, The refractive index difference between the first high refractive index layer and the first low refractive index layer at a wavelength of 500 nm is 0.49 to 1.25, and the refractive index difference between the second high refractive index layer and the second low refractive index layer at a wavelength of 500 nm is 0.49 to 1.

25.

6. The light-emitting diode chip according to any one of claims 1 to 5, characterized in that, The material of the first high refractive index layer includes at least one of TiO2, ZnS, ZnSe, Ta2O5, HfO2, and ZrO2, and the material of the second high refractive index layer includes at least one of TiO2, ZnS, ZnSe, Ta2O5, HfO2, and ZrO2.

7. The light-emitting diode chip according to any one of claims 1 to 5, characterized in that, The material of the first low refractive index layer includes at least one of SiO2, MgF2, AlF3, Na3AlF6, and BaF2, and the material of the second low refractive index layer includes at least one of SiO2, MgF2, AlF3, Na3AlF6, and BaF2.

8. The light-emitting diode chip according to any one of claims 1 to 5, characterized in that, The side of the first distributed Bragg reflector layer closest to the substrate is the first low-refractive-index layer, and the side of the first distributed Bragg reflector layer furthest from the substrate is the first high-refractive-index layer; the side of the second distributed Bragg reflector layer closest to the substrate is the second low-refractive-index layer, and the side of the second distributed Bragg reflector layer furthest from the substrate is the second high-refractive-index layer.

9. The light-emitting diode chip according to any one of claims 1 to 5, characterized in that, The groove can be a cylindrical groove, a square prism groove, or a hexagonal prism groove.

10. A method for manufacturing a light-emitting diode chip, characterized in that, include: A light-emitting structure is formed on the front side of the substrate; A first distributed Bragg reflector layer and a second distributed Bragg reflector layer are formed on the back side of the substrate. The first distributed Bragg reflector layer includes a plurality of alternating layers of first high refractive index layers and a plurality of alternating layers of first low refractive index layers. The first distributed Bragg reflector layer has an array of grooves, the depth of which is equal to the thickness of the first distributed Bragg reflector layer. The second distributed Bragg reflector layer is located in the grooves and is flush with the first distributed Bragg reflector layer. The second distributed Bragg reflector layer includes a plurality of alternating layers of second high refractive index layers and a plurality of alternating layers of second low refractive index layers.

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