A manufacturing method of a light-emitting diode

Abstract

The present invention discloses a manufacturing method of a light-emitting diode, which relates to the field of semiconductor technology. The manufacturing method includes: providing a sapphire substrate; fabricating a plurality of cylindrical pits on the surface of the sapphire substrate; filling the interior of the cylindrical pits with graphene powder for heat dissipation and light reflection; fabricating a raised silicon oxide cone doped with diamond particles directly above the cylindrical pits; growing a gallium nitride epitaxial layer to obtain an epitaxial wafer with a complete structure. The above manufacturing method can improve the heat dissipation capacity of the LED chip, effectively improve the light-emitting efficiency of the LED device, reduce the warpage of the LED epitaxial wafer, and improve the uniformity of the LED emission wavelength and brightness distribution.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and more particularly, to a method for manufacturing a light-emitting diode. Background Art

[0002] An LED (Light Emitting Diode) is a semiconductor light-emitting device mainly composed of two parts: a P-type semiconductor and an N-type semiconductor. Among them, the N-type region has many electrons with high mobility, and the P-type region has many holes with low mobility. The transition layer between the P-type semiconductor and the N-type semiconductor is called a PN junction. When a forward voltage is applied to the LED, electrons can recombine with holes and emit photons. At present, the scale of domestic LED production is gradually expanding, but there are still problems such as poor heat dissipation and low light extraction efficiency in LED chips, especially high-power LED chips, which affect the lifespan and energy-saving effect of LED devices.

[0003] Therefore, how to develop new preparation technologies on the basis of existing technologies to improve the heat dissipation ability and light-emitting efficiency of LEDs has become an urgent problem to be solved. Summary of the Invention

[0004] The present invention provides a method for manufacturing a light-emitting diode, which can improve the heat dissipation ability of an LED chip, effectively improve the light-emitting efficiency of an LED device, and can also reduce the warpage of an LED epitaxial wafer and improve the uniformity of the light-emitting wavelength and brightness distribution of the LED.

[0005] The present application provides a method for manufacturing a light-emitting diode, and the method includes:

[0006] Providing a sapphire substrate;

[0007] After performing a conventional cleaning process on the sapphire substrate, a photoresist film layer is coated on the upper surface of the sapphire substrate, and then a photolithography technique is used to form a plurality of circular patterns on the surface of the sapphire substrate with the photoresist film layer.

[0008] The sapphire substrate with a plurality of circular patterns formed on its surface is placed into an ICP reaction chamber for dry etching, and then the photoresist film layer on the surface of the sapphire substrate is removed, and a plurality of cylindrical pits are formed on the surface of the sapphire substrate; the cylindrical pits are recessed toward the sapphire substrate in a direction perpendicular to the plane where the sapphire substrate is located, and in a direction perpendicular to the plane where the sapphire substrate is located, the height of the cylindrical pits is less than the thickness of the sapphire substrate.

[0009] Filling the inside of the cylindrical pits with graphene powder for heat dissipation and light reflection;

[0010] On one side of the sapphire substrate surface where there are cylindrical pits, deposit a silicon oxide film doped with diamond particles, and then use photolithography and dry etching methods to remove the excess silicon oxide film doped with diamond particles, forming a raised silicon oxide cone doped with diamond particles directly above the cylindrical pits. Among them, the center line of the raised silicon oxide cone doped with diamond particles coincides with that of the cylindrical pits, and the bottom diameter of the raised silicon oxide cone doped with diamond particles is 1.5 times the bottom diameter of the cylindrical pits;

[0011] Finally, use metal organic chemical vapor deposition method to grow a gallium nitride buffer layer, an n-type gallium nitride layer, a multi-quantum well light-emitting layer, an electron blocking layer and a p-type gallium nitride layer in sequence on one side of the sapphire substrate surface where there is a raised silicon oxide cone doped with diamond particles, and obtain an epitaxial wafer with a complete structure.

[0012] Optionally, the diameter of the circular pattern is 500 - 600 nm, and the center distance between adjacent two circular patterns is 850 - 950 nm.

[0013] Optionally, the bottom diameter of the cylindrical pit is 500 - 600 nm, the depth of the cylindrical pit is 100 - 180 nm, and the closest distance between adjacent two cylindrical pits is 350 - 450 nm.

[0014] Optionally, the thickness of the silicon oxide film doped with diamond particles is 1100 - 1200 nm.

[0015] Optionally, the doping concentration of diamond particles in the silicon oxide film is 1*10 7 ~2*10 9 cm -3 。

[0016] Optionally, the bottom diameter of the raised silicon oxide cone doped with diamond particles is 750 - 900 nm, the height is 1100 - 1200 nm, and the closest distance between adjacent two cones is 50 - 200 nm.

[0017] Compared with the prior art, the manufacturing method of the light-emitting diode provided by the present invention has at least achieved the following beneficial effects:

[0018] In the present invention, by fabricating cylindrical pits on a sapphire substrate, on the one hand, GaN materials with high crystal quality can be obtained. This is because when growing the subsequent GaN epitaxial layer, the dislocations passing through the cylindrical pit region will bend along the crystal plane direction, thereby increasing the chance of dislocation annihilation, reducing the dislocation density of the GaN material, and thus improving the crystal quality of the epitaxial material growth. On the other hand, by filling the inside of the cylindrical pit with graphene powder, since graphene has very good thermal conductivity, the heat generated by the light-emitting diode can be quickly released; graphene has very good optical properties, and its light absorption rate is only 2.3% in a relatively wide wavelength range. Therefore, the light emitted from the multi-quantum well layer light-emitting layer can be effectively reflected rather than absorbed, and the reflected light can exit from the side wall of the light-emitting diode, which can effectively improve the light-emitting efficiency of the LED.

[0019] By fabricating a raised silicon oxide cone doped with diamond particles directly above the cylindrical pit, on the one hand, the refractive index difference between the SiO 2 material and the GaN material is relatively large to improve the light reflection efficiency. At the same time, it is more difficult for GaN to nucleate on the SiO 2 material to reduce the unintentional growth on the side walls of the pattern and improve the epitaxial crystallization quality and the light-emitting efficiency of the LED chip. On the other hand, the diamond particles have relatively high thermal conductivity, which can quickly release the heat generated by the light-emitting diode, and the refractive index of the silicon oxide doped with diamond particles is closer to that of the sapphire, which is beneficial to improving the light extraction efficiency of the LED chip. Aligning the center line of the silicon oxide cone with the cylindrical pit and making the bottom diameter of the silicon oxide cone 1.5 times the bottom diameter of the cylindrical pit, by designing such a highly symmetric structure, the GaN tends to grow laterally in a two-dimensional manner, which can reduce the warpage of the LED epitaxial wafer and improve the uniformity of the light-emitting wavelength and brightness distribution of the LED.

[0020] Of course, it is not necessary for any product implementing the present invention to achieve all the above-mentioned technical effects simultaneously.

[0021] Through the following detailed description of the exemplary embodiments of the present invention with reference to the accompanying drawings, other features and advantages of the present invention will become clear. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings incorporated in the specification and constituting a part of the specification illustrate embodiments of the present invention and, together with the description, are used to explain the principles of the present invention.

[0023] Figure 1 Shown is a schematic cross-sectional view of the complete structure of the light-emitting diode provided by the embodiment of the present application;

[0024] Figure 2The figure shows a schematic cross-section of a silicon oxide cone doped with diamond particles with cylindrical pits and protrusions provided by an embodiment of the present application;

[0025] Among them, 1 is a sapphire substrate, 2 is a cylindrical pit, 3 is a protruded silicon oxide cone doped with diamond particles, 4 is a gallium nitride buffer layer, 5 is an n-type gallium nitride layer, 6 is a multi-quantum well light-emitting layer, 7 is an electron blocking layer, and 8 is a p-type gallium nitride layer. Detailed implementation manners

[0026] Now, various exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that: unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present invention.

[0027] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended as a limitation on the present invention, its application, or its use.

[0028] Techniques, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the techniques, methods, and devices should be regarded as part of the specification.

[0029] In all the examples shown and discussed herein, any specific values should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values.

[0030] It should be noted that: like reference numerals and letters denote like items in the following drawings, and thus, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0031] The present invention provides a method for manufacturing a light-emitting diode, which can improve the heat dissipation ability of an LED chip, effectively improve the light-emitting efficiency of an LED device, reduce the warpage of an LED epitaxial wafer, and improve the uniformity of the light-emitting wavelength and brightness of an LED.

[0032] The following will be described in detail with reference to the accompanying drawings and specific embodiments.

[0033] Figure 1 The figure shows a schematic cross-section of the complete structure of a light-emitting diode provided by an embodiment of the present application; Figure 2 It is a schematic cross-section of a silicon oxide cone doped with diamond particles with cylindrical pits and protrusions provided by an embodiment of the present application. Please refer to Figure 1 - Figure 2 , the method for manufacturing a light-emitting diode includes:

[0034] Step 1: Provide a sapphire substrate 1.

[0035] Step 2: After the sapphire substrate 1 is subjected to a conventional cleaning process, a photoresist film layer is coated on the upper surface of the sapphire substrate 1, and then a photolithography technique is used to form a plurality of circular patterns on the surface of the sapphire substrate 1. The diameter of the circular patterns is 500 - 600 nm, and the center distance between adjacent two circular patterns is 850 - 950 nm.

[0036] Step 3: The sapphire substrate 1 with a plurality of circular patterns formed on its surface is placed into an ICP reaction chamber for dry etching, and then the photoresist film layer on the surface of the sapphire substrate 1 is removed. A plurality of cylindrical pits 2 with a bottom diameter R of 500 - 700 nm and a depth H of 100 - 180 nm are formed on the surface of the sapphire substrate. The closest distance D between adjacent two cylindrical pits is 350 - 450 nm; the cylindrical pits 2 are recessed towards the sapphire substrate 1 in a direction perpendicular to the plane where the sapphire substrate is located, and along the direction perpendicular to the plane where the sapphire substrate 1 is located, the height of the cylindrical pits 2 is less than the thickness of the sapphire substrate 1;

[0037] Step 4: The interior of the cylindrical pits 2 is filled with graphene powder for heat dissipation and light reflection.

[0038] Step 5: On one side of the sapphire substrate surface where the cylindrical pits 2 are formed, a silicon oxide film doped with diamond particles with a thickness of 1100 - 1200 nm is deposited. Among them, the doping concentration of the diamond particles is 1×10 7 ~2×10 9 cm -3 . Then, the redundant silicon oxide film doped with diamond particles is removed by using photolithography and dry etching methods. A raised silicon oxide cone 3 doped with diamond particles with a bottom diameter r of 750 - 900 nm and a height h of 1100 - 1200 nm is formed directly above the cylindrical pits 2. Among them, the raised silicon oxide cone 3 doped with diamond particles coincides with the center line of the cylindrical pits 2, and the bottom diameter r of the raised silicon oxide cone 3 doped with diamond particles is 1.5 times the bottom diameter R of the cylindrical pits 2, and the closest distance d between adjacent two cones is 50 - 200 nm.

[0039] Step 6: By using metalorganic chemical vapor deposition method, a gallium nitride buffer layer 4, an n-type gallium nitride layer 5, a multi-quantum well light-emitting layer 6, an electron blocking layer 7, and a p-type gallium nitride layer 8 are sequentially grown on one side of the sapphire substrate 1 where the raised silicon oxide cone 3 doped with diamond particles is formed, to obtain a fully structured epitaxial wafer.

[0040] Although some specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and not for limiting the scope of the present invention. Those skilled in the art should understand that the above embodiments can be modified without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the appended claims.

Claims

1. A manufacturing method of a light-emitting diode, characterized in that, the manufacturing method includes: providing a sapphire substrate; after performing a conventional cleaning treatment on the sapphire substrate, coating a photoresist film layer on the upper surface of the sapphire substrate, and then using photolithography technology to form a plurality of circular patterns on the surface of the sapphire substrate; placing the sapphire substrate with a plurality of circular patterns formed on its surface into an ICP reaction chamber for dry etching, and then removing the photoresist film layer on the surface of the sapphire substrate to form a plurality of cylindrical pits on the surface of the sapphire substrate; the cylindrical pits are recessed towards the sapphire substrate in a direction perpendicular to the plane where the sapphire substrate is located, and in the direction perpendicular to the plane where the sapphire substrate is located, the height of the cylindrical pits is less than the thickness of the sapphire substrate; filling the inside of the cylindrical pits with graphene powder for heat dissipation and light reflection; depositing a silicon oxide film doped with diamond particles on one side of the sapphire substrate surface where the cylindrical pits are formed, and then using photolithography and dry etching methods to remove the excess silicon oxide film doped with diamond particles to form a raised silicon oxide cone doped with diamond particles directly above the cylindrical pits, wherein the raised silicon oxide cone doped with diamond particles coincides with the center line of the cylindrical pits, and the bottom diameter of the raised silicon oxide cone doped with diamond particles is 1.5 times the bottom diameter of the cylindrical pits; finally, using metal organic chemical vapor deposition method to sequentially grow a gallium nitride buffer layer, an n-type gallium nitride layer, a multi-quantum well light-emitting layer, an electron blocking layer, and a P-type gallium nitride layer on one side of the sapphire substrate surface where the raised silicon oxide cone doped with diamond particles is formed to obtain a fully structured epitaxial wafer.

2. The manufacturing method of the light-emitting diode according to claim 1, characterized in that, the diameter of the circular pattern is 500 - 600 nm, and the center distance between adjacent two circular patterns is 850 - 950 nm.

3. The manufacturing method of the light-emitting diode according to claim 1, characterized in that, the bottom diameter of the cylindrical pit is 500 - 600 nm, the depth of the cylindrical pit is 100 - 180 nm, and the closest distance between adjacent two cylindrical pits is 350 - 450 nm.

4. The manufacturing method of the light-emitting diode according to claim 1, characterized in that, the thickness of the silicon oxide film doped with diamond particles is 1100 - 1200 nm.

5. The manufacturing method of the light-emitting diode according to claim 1, characterized in that, The doping concentration of diamond particles in the silicon oxide film is 1*10 7 ~2*10 9 cm -3 .

6. The manufacturing method of the light-emitting diode according to claim 1, characterized in that, the bottom diameter of the raised silicon oxide cone doped with diamond particles is 750 - 900 nm, the height is 1100 - 1200 nm, and the closest distance between adjacent two cones is 50 - 200 nm.

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