CN114695602A - Double-layer graphical sapphire substrate, preparation method and LED epitaxial wafer - Google Patents
Double-layer graphical sapphire substrate, preparation method and LED epitaxial wafer Download PDFInfo
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- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/005—Processes
- H01L33/0062—Processes for devices with an active region comprising only III-V compounds
- H01L33/0066—Processes for devices with an active region comprising only III-V compounds with a substrate not being a III-V compound
- H01L33/007—Processes for devices with an active region comprising only III-V compounds with a substrate not being a III-V compound comprising nitride compounds
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- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/02104—Forming layers
- H01L21/02365—Forming inorganic semiconducting materials on a substrate
- H01L21/02367—Substrates
- H01L21/0237—Materials
- H01L21/02414—Oxide semiconducting materials not being Group 12/16 materials, e.g. ternary compounds
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/02104—Forming layers
- H01L21/02365—Forming inorganic semiconducting materials on a substrate
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Abstract
The embodiment of the invention discloses a double-layer graphical sapphire substrate, a preparation method and an LED epitaxial wafer. The preparation method comprises the steps of providing a first sapphire substrate and a second sapphire substrate; forming a convex microstructure on the first surface of the first sapphire substrate, and forming a concave microstructure on the first surface of the second sapphire substrate; o is performed on the second surfaces of the first sapphire substrate and the second sapphire substrate2Plasma surface activation treatment; cleaning the second surfaces of the first sapphire substrate and the second sapphire substrate by using ammonia water to form Al-OH chemical bonds; and attaching the second surfaces of the first sapphire substrate and the second sapphire substrate to each other and carrying out vacuum heat treatment so as to bond the second surfaces of the first sapphire substrate and the second sapphire substrate to each other. Through bonding the sapphire substrates subjected to different patterning, the reflectivity of light is effectively improved, and the maximization of the light extraction rate is ensuredAnd simultaneously, the heat dissipation problem caused by the thickness of the substrate is reduced.
Description
Technical Field
The embodiment of the invention relates to the technical field of semiconductors, in particular to a double-layer graphical sapphire substrate, a preparation method and an LED epitaxial wafer.
Background
Since the 20 th century, low-carbon economy or resource-saving development based on low energy consumption, low emission and low pollution has been taken as an important direction of future sustainable development in various countries, and Light Emitting diodes (Light Emitting diodes) play an important role in the field of illumination with huge electric power demand. The GaN-based LED chip has the advantages of high electro-optic conversion efficiency, energy conservation, environmental protection, long service life, small volume and the like, and is widely applied to industrial and general illumination.
Sapphire materials are used as the epitaxial materials of the current mainstream GaN-based LED chips due to the characteristics of moderate price, good chemical stability, high mechanical strength, good light transmittance and the like, but the LED luminous efficiency and the service life are greatly influenced due to the large lattice mismatch degree and the large thermal expansion coefficient of the sapphire materials and GaN. In order to solve the defects of Sapphire, a Patterned Sapphire Substrate (PSS) technology is proposed. The PSS technology is to process the surface of sapphire in a micro-processing mode to obtain a pattern microstructure with certain periodicity. The graphical interface can change the incident angle of light reaching the GaN-sapphire interface, so that the internal total reflection of the LED is inhibited, and the light extraction efficiency of the GaN-based LED device is improved. In addition, due to the existence of the pattern inclined plane, the growth mode of the epitaxial GaN film on the PSS substrate is changed, the dislocation density of the epitaxial layer is reduced, and the internal quantum efficiency of the active layer MQW is remarkably improved. However, most of the existing patterned substrates are modified in patterns, which are developed from the initial groove shape to various patterns, and only modifying the shape of the microstructure of the pattern has a limited effect on the light extraction and epitaxial quality of the whole LED device, resulting in low light extraction efficiency of the LED.
Disclosure of Invention
The invention provides a double-layer graphical sapphire substrate, a preparation method and an LED epitaxial wafer, which are used for increasing the reflectivity of light and obtaining higher light-emitting rate.
In a first aspect, an embodiment of the present invention provides a method for preparing a double-layer patterned sapphire substrate, including:
providing a first sapphire substrate and a second sapphire substrate, wherein the first sapphire substrate and the second sapphire substrate respectively comprise a first surface and a second surface which are mutually deviated;
forming a convex microstructure on the first surface of the first sapphire substrate, and forming a concave microstructure on the first surface of the second sapphire substrate;
o is performed to the second surfaces of the first and second sapphire substrates2Plasma surface activation treatment;
cleaning the second surfaces of the first sapphire substrate and the second sapphire substrate by using ammonia water to form Al-OH chemical bonds;
and mutually attaching the second surfaces of the first sapphire substrate and the second sapphire substrate, and carrying out vacuum heat treatment to mutually bond the second surfaces of the first sapphire substrate and the second sapphire substrate.
Optionally, before forming the protruding microstructures on the first surface of the first sapphire substrate and forming the recessed microstructures on the first surface of the second sapphire substrate, the method further includes:
cleaning and drying the first surfaces of the first and second sapphire substrates;
and/or performing O on the second surfaces of the first and second sapphire substrates2Before the plasma surface activation treatment, the method also comprises the following steps:
and cleaning and drying the second surfaces of the first sapphire substrate and the second sapphire substrate.
Optionally, the cleaning and drying process performed on the first surfaces of the first and second sapphire substrates includes:
placing the first and second sapphire substrates in H2SiO4And H2O2Pickling in the mixed solution for 20-30 min;
and taking out the first sapphire substrate and the second sapphire substrate and carrying out spin-drying or drying treatment.
Optionally, the cleaning and drying process performed on the second surfaces of the first and second sapphire substrates includes:
using ammonia and H2O2Cleaning the first sapphire substrate and the second sapphire substrate for 10-20min by using a mixed RCA solution;
rinsing the first and second sapphire substrates with a 0.025-0.05% HF solution;
and placing the first sapphire substrate and the second sapphire substrate in an air environment of 200-300 ℃ for drying treatment.
Optionally, after forming the protruding microstructures on the first surface of the first sapphire substrate and forming the recessed microstructures on the first surface of the second sapphire substrate, the method further includes:
and thinning the second surfaces of the first sapphire substrate and the second sapphire substrate.
Optionally, the concentration of the ammonia water is 20-30%.
Optionally, forming a protruding microstructure on the first surface of the first sapphire substrate and forming a recessed microstructure on the first surface of the second sapphire substrate comprises:
forming a first dielectric layer on the first surface of the first sapphire substrate, and patterning the first dielectric layer or the first dielectric layer and the first sapphire substrate to form the raised microstructure;
patterning the first surface of the second sapphire substrate to form the dimple microstructure;
and forming a second dielectric layer on the first surface of the second sapphire substrate, wherein the second dielectric layer fills the pit microstructures.
In a second aspect, an embodiment of the present invention provides a double-layer patterned sapphire substrate, which is manufactured by using the method for manufacturing a double-layer patterned sapphire substrate according to any one of the first aspect;
the patterned sapphire substrate comprises a first sapphire substrate and a second sapphire substrate, and the first sapphire substrate and the second sapphire substrate respectively comprise a first surface and a second surface which are mutually deviated;
the first surface of the first sapphire substrate is provided with a raised microstructure; a pit microstructure is formed on the first surface of the second sapphire substrate; the second surfaces of the first and second sapphire substrates are bonded to each other.
Optionally, the raised microstructure comprises a dielectric structure layer and a sapphire layer, wherein the dielectric structure layer is positioned on the side of the sapphire layer facing away from the second sapphire substrate;
and one side of the second sapphire substrate, which is far away from the first sapphire substrate, further comprises a second dielectric layer, and the second dielectric layer covers the second surface of the second sapphire substrate and fills the pit microstructures.
Optionally, the shape of the protruding microstructure comprises at least one of a cone, a frustum, a spherical segment and a cube, or the shape of the protruding microstructure comprises a cone-like body and a frustum-like body with side wall radian;
the shape of the pit microstructure comprises at least one of a cone, a table body, a spherical segment and a cube, or the shape of the pit microstructure comprises a cone-like body and a table-like body with side wall radians.
Optionally, the material of the first dielectric layer includes SiO2、AlN、Si3N4At least one of; the material of the second dielectric layer comprises at least one of SiC and AlN.
In a third aspect, an embodiment of the present invention provides an LED epitaxial wafer, including the double-layer patterned sapphire substrate of any one of the second aspects, and further including an epitaxial layer on the double-layer patterned sapphire substrate.
The embodiment of the invention provides a preparation method of a double-layer graphical sapphire substrate, which comprises the following steps: providing a first sapphire substrate and a second sapphire substrate, wherein the first sapphire substrate and the second sapphire substrate respectively comprise a first surface and a second surface which are mutually deviated; forming protrusions on a first surface of a first sapphire substrateForming a pit microstructure on the first surface of the second sapphire substrate; o is performed on the second surfaces of the first sapphire substrate and the second sapphire substrate2Plasma surface activation treatment; cleaning the second surfaces of the first sapphire substrate and the second sapphire substrate by using ammonia water to form Al-OH chemical bonds; and attaching the second surfaces of the first sapphire substrate and the second sapphire substrate to each other and carrying out vacuum heat treatment so as to bond the second surfaces of the first sapphire substrate and the second sapphire substrate to each other. The embodiment of the invention solves the problem that the existing graphical substrate is limited in improving the light-emitting efficiency of the LED, not only can a double-layer sapphire graphical substrate be realized, but also the reflection of light is increased, the reflection efficiency is improved, the light regulation effect is improved and the light-emitting efficiency of an LED chip is further improved by utilizing the difference of structural characteristics such as the side slope of a two-layer graphic microstructure.
Drawings
Fig. 1 is a schematic flow chart of a method for manufacturing a double-layer patterned sapphire substrate according to an embodiment of the present invention;
fig. 2 is a structural flow chart of a method for preparing a double-layer patterned sapphire substrate according to an embodiment of the present invention;
fig. 3 is a schematic flowchart of another method for manufacturing a double-layer patterned sapphire substrate according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of a double-layer patterned sapphire substrate according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of an LED epitaxial wafer according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
Fig. 1 is a schematic flow chart of a method for manufacturing a double-layer patterned sapphire substrate according to an embodiment of the present invention, and as shown in fig. 1, the method for manufacturing a double-layer patterned sapphire substrate includes:
s101, providing a first sapphire substrate and a second sapphire substrate, wherein the first sapphire substrate and the second sapphire substrate respectively comprise a first surface and a second surface which are mutually deviated.
S102, forming a protruding microstructure on the first surface of the first sapphire substrate, and forming a pit microstructure on the first surface of the second sapphire substrate.
Fig. 2 is a flow chart of a structure of a double-layer patterned sapphire substrate according to an embodiment of the present invention, which exemplarily illustrates a protrusion microstructure formed on a first surface of a first sapphire substrate and a pit microstructure formed on a first surface of a second sapphire substrate, and referring to fig. 1 and fig. 2, a first dielectric layer 111 is formed on the first surface of the first sapphire substrate 11 by MOCVD or PVD deposition coating, and a photoresist developing process of glue coating, exposure, and development is performed to obtain a first photoresist mask layer 112. And etching the first sapphire substrate 11 with the first photoresist mask layer 112 by adopting dry etching or wet etching to obtain the protruding microstructure 113 with the size of 2.5-3.5um of bottom diameter and 1.0-2.0um of height. Optionally, in this embodiment, an over-etching process exists in the etching process of the first dielectric layer 111, that is, after the first dielectric layer 111 is completely etched, the exposed first sapphire substrate 11 also has a certain degree of etching, where the etching depth of sapphire may be 100-. The raised microstructure 113 includes a dielectric layer and a sapphire layer, and the dielectric layer is located on a side of the sapphire layer facing away from the first sapphire substrate. The first dielectric layer 111 is used to form the protruding microstructures 113, and the reflective interface can be formed by using the refractive index difference between the first dielectric layer 111 and the sapphire substrate. Meanwhile, the raised microstructures 113 made of the dielectric material can also form a reflective interface with the epitaxial layer, and the raised microstructures 113 can be made of the dielectric material with a lower refractive index, so that when light enters the raised microstructures 113 from the epitaxial layer, the light is substantially a propagation path from dense light to sparse light, the dielectric material with the lower refractive index can increase the total reflection angle of the interface, namely the total reflection probability of the interface can be increased, and more light can be reflected at the interface. In addition, due to the existence of the structural features such as the side wall of the protruding microstructure 113, the slope of the interface is also changed, and the probability of light reflection is further increased.
A positive photoresist negative developing and a negative photoresist positive developing process of gluing, exposing and developing or a mask prepared by adopting a protruding microstructure different from the first sapphire substrate 11 are carried out on the first surface of the second sapphire substrate 12 to obtain a second photoresist mask layer 121 complementary to the first photoresist mask layer 112. The second sapphire substrate 12 having the second photoresist mask layer 121 is etched by dry or wet etching, so that the pit microstructure 123 having a bottom diameter of 2.5-3.5um and a depth of 1.0-2.0um can be obtained. Also, optionally, in this embodiment, the second dielectric layer 122 may be formed on the pit microstructure 123 by MOCVD or PVD deposition, that is, the second dielectric layer 122 covers the second surface of the second sapphire substrate 12 and fills the pit microstructure 123. At this time, the pit microstructures 123 may form a reflective interface using a refractive index difference between the second dielectric layer 122 and the sapphire substrate. Moreover, the second dielectric layer 122 can not only form a reflective interface with the second sapphire substrate 12, but also form an interface with the outside air, when the refractive index of the second dielectric layer 122 is higher than that of the sapphire substrate, the difference between the refractive indexes of the second dielectric layer and the air layer at two sides of the interface is increased, and the light transmitted by the epitaxial layer is transmitted from dense light to sparse light at the interface, so that the angle of total reflection can be increased, the total reflection can be more easily generated, and the reflection probability is increased.
In addition, the protruding microstructures 113 formed on the first surface of the first sapphire substrate 11 and the recessed microstructures 123 formed on the first surface of the second sapphire substrate 12 are arranged in a staggered manner, so that a light reflection interface can be provided to the maximum extent, and the light reflection capability of the patterned substrate is improved.
S103, carrying out O on the second surfaces of the first sapphire substrate and the second sapphire substrate2And (5) carrying out plasma surface activation treatment.
Wherein the step is essentially a first step of pretreatment of the first sapphire substrate and the second sapphire substrate before bonding. O is2Plasma surface activation treatmentAnd multiple chemical or physical changes can be generated on the second surfaces of the first sapphire substrate and the second sapphire substrate, so that the surface energy is improved. O-treating the second surfaces of the first and second sapphire substrates for 30-300s2And performing plasma surface activation treatment to enable the surface state to meet the process requirement of subsequent bonding.
And S104, cleaning the second surfaces of the first sapphire substrate and the second sapphire substrate by using ammonia water to form Al-OH chemical bonds.
The step is a process of performing a second step of pretreatment on the first sapphire substrate and the second sapphire substrate before bonding. The active chemical bond for bonding can be formed on the surface of the sapphire by treating the sapphire with ammonia water, so that the close bonding of two sapphire substrates is facilitated. Alternatively, the concentration of ammonia in this step may be selected to be 20-30%.
And S105, mutually attaching the second surfaces of the first sapphire substrate and the second sapphire substrate, and carrying out vacuum heat treatment to mutually bond the second surfaces of the first sapphire substrate and the second sapphire substrate.
Continuing to refer to fig. 2, the second surfaces of the first sapphire substrate 11 and the second sapphire substrate 12 after being processed are mutually bonded, and are placed in a vacuum chamber for vacuum heat treatment under the conditions of 400-2And O, further realizing the mutual bonding of the second surfaces of the first sapphire substrate and the second sapphire substrate to form the double-layer patterned sapphire substrate.
In this embodiment, the protruding microstructures are formed on the first surface of the first sapphire substrate, the pit microstructures are formed on the first surface of the second sapphire substrate, and plasma surface activation is performed on the second surfaces of the first sapphire substrate and the second sapphire substrate, so that mutual plasma activation bonding of the second surfaces of the first sapphire substrate and the second sapphire substrate is realized, a double-layer patterned sapphire substrate is obtained, and the double-layer sapphire substrate is integrated. On the basis of double-layer imaging, by means of the two layers of graphic microstructures, the difference of structural characteristics such as the side slope of the two layers of graphic microstructures can be utilized, reflection of light is increased, reflection efficiency is improved, the regulation and control effect of the light is improved, and the light emitting efficiency of the LED chip is further improved.
Specifically, fig. 3 is a schematic flow chart of a method for manufacturing a double-layer patterned sapphire substrate according to an embodiment of the present invention, as shown in fig. 3. The preparation method of the double-layer graphical sapphire substrate comprises the following steps:
s301, providing a first sapphire substrate and a second sapphire substrate, wherein the first sapphire substrate and the second sapphire substrate respectively comprise a first surface and a second surface which are mutually deviated.
S302, cleaning and drying the first surfaces of the first sapphire substrate and the second sapphire substrate.
And S303, forming a convex microstructure on the first surface of the first sapphire substrate, and forming a concave microstructure on the first surface of the second sapphire substrate.
Optionally, the shape of the protruding microstructure comprises at least one of a cone, a table, a segment, and a cube, or the shape of the protruding microstructure comprises a cone-like body and a table-like body with a sidewall arc; the shape of the pit microstructure comprises at least one of a cone, a platform, a spherical segment and a cube, or the shape of the pit microstructure comprises a cone-like body and a platform-like body with side wall radian.
As shown in fig. 2, the shape of the protruding microstructure 113 is a cone structure, and the shape of the pit microstructure 123 is a segment-like structure. In other embodiments of the present invention, the actual etching rate can be changed by adjusting the dry or wet etching process parameters and environment, so that the formed cone-like structure or mesa-like structure has a certain sidewall radian, i.e., a cone-like or mesa-like structure is formed.
And S304, cleaning and drying the second surfaces of the first sapphire substrate and the second sapphire substrate.
S305, aligning the first sapphire substrate and the second sapphire substrateThe second surface of the substrate is all O2And (5) performing plasma surface activation treatment.
S306, cleaning the second surfaces of the first sapphire substrate and the second sapphire substrate by using ammonia water to form Al-OH chemical bonds.
And S307, thinning the second surfaces of the first sapphire substrate and the second sapphire substrate.
It can be understood that the thinning step of S307 is added, and the main purpose of the thinning step is to relatively increase the thicknesses of the first sapphire substrate and the second sapphire substrate when the first sapphire substrate and the second sapphire substrate are provided in step S301, at this time, the first sapphire substrate and the second sapphire substrate have stronger rigidity, and when a microstructure is formed thereon, the problem of cracking due to the excessively thin substrates can be avoided, and the quality of the patterned two substrates can be ensured. Specifically, the thickness of the first sapphire substrate and the second sapphire substrate after thinning treatment is 100-200um, and plasma activation bonding is utilized to realize integration of the double-layer patterned substrates, so that the whole substrate can have a thinner thickness, the problem of difficulty increase of processing and heat dissipation caused by over-thick substrate is avoided, and the processing and heat dissipation of the LED chip are facilitated.
And S308, mutually attaching the second surfaces of the first sapphire substrate and the second sapphire substrate, and carrying out vacuum heat treatment to mutually bond the second surfaces of the first sapphire substrate and the second sapphire substrate.
The first surfaces and the second surfaces of the first sapphire substrate and the second sapphire substrate are cleaned and dried, so that the cleanness of the first surfaces and the second surfaces of the first sapphire substrate and the second sapphire substrate can be guaranteed.
Optionally, the cleaning and drying process is performed on the second surfaces of the first sapphire substrate and the second sapphire substrate, and includes:
using ammonia and H2O2Cleaning the first sapphire substrate and the second sapphire substrate for 10-20min by using the mixed RCA solution;
rinsing the first sapphire substrate and the second sapphire substrate with 0.025-0.05% HF solution;
and placing the first sapphire substrate and the second sapphire substrate in an air environment of 200-300 ℃ for drying treatment.
Wherein ammonia and H are utilized2O2Cleaning the first sapphire substrate and the second sapphire substrate by using the mixed RCA solution, and removing surface metal impurities on the second surfaces of the first sapphire substrate and the second sapphire substrate; and the first sapphire substrate and the second sapphire substrate are washed by using 0.025-0.05% HF solution, so that the cleanness of the first sapphire substrate and the second sapphire substrate is further ensured.
Optionally, forming a protruding microstructure on the first surface of the first sapphire substrate and forming a recessed microstructure on the first surface of the second sapphire substrate comprises:
forming a first dielectric layer on the first surface of the first sapphire substrate, and patterning the first dielectric layer or the first dielectric layer and the first sapphire substrate to form a convex microstructure;
patterning the first surface of the second sapphire substrate to form a pit microstructure;
and forming a second medium layer on the first surface of the second sapphire substrate, wherein the second medium layer is filled with the pit microstructures.
The first dielectric layer is used for preparing and forming the protruding microstructure, so that the problem of stress concentration when an epitaxial layer is formed on the sapphire substrate can be reduced, and the lattice defect of an epitaxial material (such as gallium nitride) is reduced, so that the epitaxial growth quality is improved. And depositing a coating film on the first surface of the second sapphire substrate by MOCVD or PVD to form a second dielectric layer, and filling the pit microstructure with the second dielectric layer.
Specifically, the material of the first dielectric layer comprises SiO2、AlN、Si3N4At least one of; the material of the second dielectric layer comprises at least one of SiC and AlN. The thickness of the first dielectric layer can be set to be 2-5um, and SiO in the material of the first dielectric layer2、AlN、Si3N4Have refractive indices of 1.46, 2.16 and 2.04 respectively, which are lower than the refractive index of GaN (n is 2.56), so that the difference between the refractive indices of the protruding microstructure and the epitaxial layer can be ensured, and the light can be ensuredThe line is close to the light beam at the interface of the epitaxial layer and the protruding microstructure, the total reflection angle is increased in response to the increase of the refractive index difference, namely the probability of total reflection of the light beam at the interface is increased, so that the reflectivity of the light beam is improved; the thickness of the second dielectric layer is 1-2um, and in the material of the second dielectric layer, the refractive index of SiC is 2.64, the thermal conductivity is 490W/(m K), the refractive index of AlN is 2.16, and the thermal conductivity is 270W/(m K); the refractive index is higher than that of the sapphire substrate (n is 1.78), compared with the interface formed by the second sapphire substrate and the air layer, the difference of the refractive indexes of the interface formed by the second dielectric layer and the air layer is larger, when light passes through the interface of the second dielectric layer and the air layer, the total reflection angle of the light is increased due to the larger difference of the refractive indexes, the light is easier to be totally reflected at the interface, namely, the reflection probability can be increased to avoid the light from being emitted, so that the reflection efficiency is improved, and the light emitting efficiency of the front surface of the LED is improved. In addition, the second dielectric layer is made of a material with better heat conductivity, and the heat dissipation problem caused by the thickness of the composite structure substrate is reduced.
In the embodiment, the second surfaces of the first sapphire substrate and the second sapphire substrate are bonded with each other by forming the protruding microstructures on the first surface of the first sapphire substrate and forming the pit microstructures on the first surface of the second sapphire substrate and processing the second surfaces of the first sapphire substrate and the second sapphire substrate, so that the double-layer patterned sapphire substrate is obtained. The embodiment of the invention solves the problem that the existing patterned substrate is limited for improving the light-emitting efficiency of the LED, not only can realize the double-layer sapphire patterned substrate, but also can increase the total reflection angle of the interface, increase the reflection of light, improve the reflection efficiency, improve the regulation and control effect of the light and further improve the light-emitting efficiency of the LED chip by utilizing the difference of the structural characteristics such as the side slope of the two layers of patterned microstructures and the like and the refractive index difference of the interface. In addition, in the embodiment of the invention, the protruding microstructures are formed by utilizing the first medium layer and the pit microstructures are formed by utilizing the second medium layer, so that the heat dissipation capability of the substrate can be improved to a certain extent by utilizing the good heat conduction performance of the medium material; meanwhile, the thickness of the whole substrate can be effectively reduced through the thinning treatment step in the preparation process, and the heat dissipation problem caused by the thicker thickness is prevented.
Fig. 4 is a schematic structural diagram of a double-layer patterned sapphire substrate according to an embodiment of the present invention, and as shown in fig. 4, the double-layer patterned sapphire substrate is manufactured by using the method for manufacturing a double-layer patterned sapphire substrate according to any one of the embodiments;
the patterned sapphire substrate comprises a first sapphire substrate 11 and a second sapphire substrate 12, the first sapphire substrate 11 and the second sapphire substrate 12 both comprise a first surface and a second surface which are away from each other, as shown, the first sapphire substrate 11 comprises a first surface 101 and a second surface 103, and the second sapphire substrate 12 comprises a first surface 102 and a second surface 104; the first surface 101 of the first sapphire substrate 11 is formed with a raised microstructure 113; the first surface 102 of the second sapphire substrate 12 is formed with a pit microstructure 123; the second surface 103 of the first sapphire substrate 11 and the second surface 104 of the second sapphire substrate 12 are bonded to each other.
In this embodiment, the integrated double-layer patterned sapphire substrate is obtained by forming the protruding microstructure on the first surface of the first sapphire substrate, forming the pit microstructure on the first surface of the second sapphire substrate, and performing plasma surface activation on the second surfaces of the first sapphire substrate and the second sapphire substrate to realize mutual plasma activation bonding of the second surfaces of the first sapphire substrate and the second sapphire substrate. On the basis of double-layer imaging, by means of the two layers of graphic microstructures, the difference of structural characteristics such as the side slope of the two layers of graphic microstructures can be utilized, reflection of light is increased, reflection efficiency is improved, the regulation and control effect of the light is improved, and the light emitting efficiency of the LED chip is further improved. In addition, the whole substrate can be ensured to have thinner thickness, the problems of processing and heat dissipation difficulty improvement caused by over-thick substrate are avoided, and the processing and heat dissipation of the LED chip are facilitated.
Fig. 5 is a schematic structural diagram of an LED epitaxial wafer according to an embodiment of the present invention, and as shown in fig. 5, the LED epitaxial wafer includes any one of the double-layer patterned sapphire substrates 301 provided in the above embodiments, and further includes an epitaxial layer 302 on the double-layer patterned sapphire substrate.
Since the LED epitaxial wafer provided in this embodiment includes the double-layer patterned sapphire substrate provided in the above embodiment, the LED epitaxial wafer has the same or corresponding beneficial effects as the double-layer patterned sapphire substrate, and details are not repeated here.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious modifications, rearrangements, combinations and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.
Claims (12)
1. A preparation method of a double-layer patterned sapphire substrate is characterized by comprising the following steps:
providing a first sapphire substrate and a second sapphire substrate, wherein the first sapphire substrate and the second sapphire substrate respectively comprise a first surface and a second surface which are opposite to each other;
forming a convex microstructure on the first surface of the first sapphire substrate, and forming a concave microstructure on the first surface of the second sapphire substrate;
o is performed to the second surfaces of the first and second sapphire substrates2Plasma surface activation treatment;
cleaning the second surfaces of the first sapphire substrate and the second sapphire substrate by using ammonia water to form Al-OH chemical bonds;
and mutually attaching the second surfaces of the first sapphire substrate and the second sapphire substrate, and carrying out vacuum heat treatment to mutually bond the second surfaces of the first sapphire substrate and the second sapphire substrate.
2. The method for preparing a double-layer patterned sapphire substrate according to claim 1, wherein before forming the protruding microstructures on the first surface of the first sapphire substrate and forming the recessed microstructures on the first surface of the second sapphire substrate, the method further comprises:
cleaning and drying the first surfaces of the first and second sapphire substrates;
and/or O is performed on the second surfaces of the first and second sapphire substrates2Before the plasma surface activation treatment, the method also comprises the following steps:
and cleaning and drying the second surfaces of the first sapphire substrate and the second sapphire substrate.
3. The method for producing a double-layered patterned sapphire substrate according to claim 2, wherein the cleaning and drying process is performed on the first surfaces of the first and second sapphire substrates, and includes:
placing the first and second sapphire substrates in H2SiO4And H2O2Acid washing in the mixed solution for 20-30 min;
and taking out the first sapphire substrate and the second sapphire substrate and carrying out spin-drying or drying treatment.
4. The method for producing a double-layered patterned sapphire substrate according to claim 2, wherein the cleaning and drying process is performed on the second surfaces of the first and second sapphire substrates, and includes:
using ammonia and H2O2Cleaning the first sapphire substrate and the second sapphire substrate for 10-20min by using a mixed RCA solution;
rinsing the first and second sapphire substrates with a 0.025-0.05% HF solution;
and placing the first sapphire substrate and the second sapphire substrate in an air environment at 200-300 ℃ for drying treatment.
5. The method for preparing a double-layer patterned sapphire substrate according to claim 1, wherein after forming the protruding microstructures on the first surface of the first sapphire substrate and forming the recessed microstructures on the first surface of the second sapphire substrate, the method further comprises:
and thinning the second surfaces of the first sapphire substrate and the second sapphire substrate.
6. The method for producing a double-layered patterned sapphire substrate according to claim 1, wherein the concentration of the aqueous ammonia is 20 to 30%.
7. The method for preparing a double-layer patterned sapphire substrate according to claim 1, wherein the forming of the protruding microstructures on the first surface of the first sapphire substrate and the forming of the recessed microstructures on the first surface of the second sapphire substrate comprises:
forming a first dielectric layer on the first surface of the first sapphire substrate, and patterning the first dielectric layer or the first dielectric layer and the first sapphire substrate to form the raised microstructure;
patterning the first surface of the second sapphire substrate to form the dimple microstructure;
and forming a second dielectric layer on the first surface of the second sapphire substrate, wherein the second dielectric layer fills the pit microstructures.
8. A double-layer patterned sapphire substrate, which is produced by the method for producing a double-layer patterned sapphire substrate according to any one of claims 1 to 7;
the patterned sapphire substrate comprises a first sapphire substrate and a second sapphire substrate, and the first sapphire substrate and the second sapphire substrate respectively comprise a first surface and a second surface which are mutually deviated;
the first surface of the first sapphire substrate is provided with a raised microstructure; a pit microstructure is formed on the first surface of the second sapphire substrate; the second surfaces of the first and second sapphire substrates are bonded to each other.
9. The double-layer patterned sapphire substrate of claim 8, wherein the raised microstructures comprise a dielectric structure layer and a sapphire layer, the dielectric structure layer being located on a side of the sapphire layer facing away from the second sapphire substrate;
and one side of the second sapphire substrate, which is far away from the first sapphire substrate, further comprises a second dielectric layer, and the second dielectric layer covers the second surface of the second sapphire substrate and fills the pit microstructures.
10. The double-layer patterned sapphire substrate of claim 8, wherein the shape of the raised microstructures comprises at least one of a pyramid, a mesa, a segment, and a cube, or the shape of the raised microstructures comprises a pyramid-like, a mesa-like body with sidewall curvature;
the shape of the pit microstructure comprises at least one of a cone, a table body, a spherical segment and a cube, or the shape of the pit microstructure comprises a cone-like body and a table-like body with side wall radians.
11. The double-layered patterned sapphire substrate of claim 8, wherein the material of the first dielectric layer comprises SiO2、AlN、Si3N4At least one of; the material of the second dielectric layer comprises at least one of SiC and AlN.
12. An LED epitaxial wafer comprising the double-layer patterned sapphire substrate of any one of claims 8-11, further comprising an epitaxial layer on the double-layer patterned sapphire substrate.
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| CN117096238A (en) * | 2023-10-18 | 2023-11-21 | 江西兆驰半导体有限公司 | Composite substrate, preparation method thereof and LED chip |
| CN117096238B (en) * | 2023-10-18 | 2024-04-09 | 江西兆驰半导体有限公司 | Composite substrate, preparation method thereof and LED chip |
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