A method for roughening gallium nitride layers

Abstract

This invention discloses a method for roughening a gallium nitride (GaN) layer, relating to the field of semiconductor technology. The method includes providing a wafer to be roughened, the wafer including a substrate and a GaN layer disposed on the substrate; etching the GaN layer at predetermined intervals and angles until the substrate is exposed to form a plurality of GaN sublayers; oxidizing the etched wafer in an oxidation solution for a first predetermined time; and oxidizing the oxidized wafer in a roughening solution, ultrasonicating the wafer at a predetermined frequency and temperature for a second predetermined time to roughen the sidewalls and surface of the GaN sublayers. This invention solves the technical problems of poor surface roughening quality and damage in existing GaN layers.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and more specifically to a method for roughening gallium nitride layers. Background Technology

[0002] LED (Light Emitting Diode) is a semiconductor device that emits light by releasing energy when charge carriers recombine. LED chips have many advantages, including low power consumption, pure color, long lifespan, small size, fast response time, and energy efficiency, and have gradually replaced incandescent and fluorescent lamps, becoming the primary light source for ordinary household lighting. However, III-V group semiconductors generally have a high refractive index, meaning that most of the light emitted from the LED's emitting region is lost due to total internal reflection at the interface, with only a very small portion escaping to the outside. This interface total internal reflection phenomenon leads to low external quantum efficiency in LEDs, which is the main reason limiting the replacement of existing lighting devices with LEDs.

[0003] To improve light extraction efficiency, surface roughening technology is widely used in the industry as a simple and effective method. However, since the LED surface is composed of gallium nitride (GaN) crystals grown at high temperatures, it has high hardness and excellent corrosion resistance. Traditional industrial physical roughening techniques are not suitable for processing this type of material. Industry research has found that plasma and chemical etching methods can effectively etch gallium nitride (GaN) crystals. Plasma etching of GaN crystals is fast and has strong etching capabilities, but it can cause irreversible damage to the crystal surface. Improper processes can easily lead to electrical performance defects in the crystal, ultimately causing the chip to burn out and become unusable. Chemical etching does not damage the crystal surface, but its disadvantages are slow etching speed and difficulty in controlling the surface morphology due to the long process time. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide a method for roughening gallium nitride layers, which aims to solve the technical problems of poor surface roughening quality and damage in gallium nitride layers in the prior art.

[0005] One aspect of the present invention is to provide a method for roughening a gallium nitride layer, the method comprising:

[0006] A wafer to be roughened is provided, the wafer including a substrate and a gallium nitride layer disposed on the substrate;

[0007] The gallium nitride layer is etched at a preset angle at a preset distance until the substrate is exposed, so as to form a plurality of gallium nitride sublayers;

[0008] The etched wafer is placed in an oxidation solution for oxidation for a first preset time;

[0009] The oxidized wafer is placed in a roughening solution and ultrasonicated at a preset frequency and temperature for a second preset time to roughen the sidewalls and surface of the gallium nitride sublayer.

[0010] Compared with the prior art, the beneficial effects of the present invention are as follows: The gallium nitride (GaN) layer roughening method provided by the present invention involves etching the GaN layer at preset distances and angles until the substrate is exposed, forming several GaN sublayers. The increased sidewalls improve LED light extraction efficiency. The etched wafer is then placed in an oxidation solution for a first preset time to oxidize and soften the surface and sidewalls of the GaN sublayers. The oxidized wafer is then placed in a roughening solution and ultrasonicated at a preset frequency and temperature for a second preset time to further soften the GaN sublayers. The sidewalls and surface of the gallium sublayer are roughened by forming cavitation bubbles in an ultrasonic environment using a roughening liquid. These bubbles carry particles in the roughening liquid to impact the sidewalls and surface of the gallium nitride sublayer, thus roughening the sidewalls and surface of the gallium nitride sublayer. This roughening method is simple and effective, combining chemical catalysis and physical impact technology to form a uniformly roughened gallium nitride sublayer with good roughness. The surface and sidewalls of the gallium nitride sublayer are undamaged, further improving the light output efficiency of LEDs. This solves the common technical problem of poor surface roughening quality and damage in gallium nitride layers.

[0011] According to one aspect of the above technical solution, the oxidation solution includes an oxidant, a catalyst, and water, wherein the oxidant is hydrogen peroxide, and the catalyst is Fe3O4 or FeSO4.

[0012] According to one aspect of the above technical solution, the concentration of hydrogen peroxide is 2.5%-12.5%.

[0013] According to one aspect of the above technical solution, the concentration of the FeSO4 solution is 0.2-0.5 mol / L.

[0014] According to one aspect of the above technical solution, the roughening solution includes silicon oxide and aluminum oxide, wherein the concentration of silicon oxide is 2%-4% and the concentration of aluminum oxide is 3%-5%.

[0015] According to one aspect of the above technical solution, the particle size of both the silicon oxide and the aluminum oxide is 0.01-0.1 μm.

[0016] According to one aspect of the above technical solution, the preset angle is 5-15°.

[0017] According to one aspect of the above technical solution, the first preset time is 10-15 minutes, and the second preset time is 15-25 minutes.

[0018] According to one aspect of the above technical solution, the preset frequency is 20-60 kHz, and the preset temperature is 25-35°C. Attached Figure Description

[0019] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0020] Figure 1 This is a flowchart of the gallium nitride layer roughening method in the first embodiment of the present invention;

[0021] Figure 2 This is a schematic diagram illustrating the method for roughening the gallium nitride layer in the first embodiment of the present invention.

[0022] Figure 1 is a schematic diagram of the high-speed microjets, Figure 2 is a structural diagram of the wafer to be roughened, and Figure 3 is a schematic diagram of the gallium nitride sublayer roughening.

[0023] Component symbol explanation in the attached diagram:

[0024] Substrate 100, gallium nitride layer 200, gallium nitride sublayer 201. Detailed Implementation

[0025] To make the objectives, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Several embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of the present invention will be more thorough and complete.

[0026] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," "upper," "lower," and similar expressions used herein are for illustrative purposes only and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the invention.

[0027] In this invention, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances. The term "and / or" as used herein includes any and all combinations of one or more of the related listed items.

[0028] Example 1

[0029] Please see Figure 1 The image shows a method for roughening a gallium nitride layer according to a first embodiment of the present invention. The method for roughening the gallium nitride layer includes steps S10-S11:

[0030] Step S10: Provide a wafer to be roughened, the wafer including a substrate and a gallium nitride layer disposed on the substrate;

[0031] The substrate 100 is the substrate for epitaxial layer growth and support. Different substrate 100 materials determine different epitaxial growth techniques and chip processing techniques. A gallium nitride layer 200 is provided on the substrate 100. Gallium nitride material has excellent physical properties, such as high melting point, corrosion resistance, wide band gap, and low dielectric constant, making it a new type of semiconductor material for the development of microelectronic devices and optoelectronic devices.

[0032] Step S11: The gallium nitride layer is etched at a preset angle at a preset distance until the substrate is exposed, so as to form a plurality of gallium nitride sublayers;

[0033] In order to improve the light output efficiency of LED, the gallium nitride layer 200 on the LED surface needs to be roughened. Currently, the light output efficiency of LED is improved by roughening the surface structure or shape structure of the gallium nitride layer 200. However, this surface roughening of the gallium nitride layer 200 has limited effect on improving the light output efficiency of LED. If the sidewalls of the gallium nitride layer 200 are roughened, the light output efficiency of LED will be further improved.

[0034] Therefore, the sidewalls of the gallium nitride layer 200 need to be roughened. In order to further improve the light extraction efficiency of the LED, the gallium nitride layer needs to be etched at a preset angle at a preset distance until the substrate is exposed to form several gallium nitride sublayers 201. Roughening the sidewalls of several gallium nitride sublayers 201 will further improve the light extraction efficiency of the LED.

[0035] Specifically, the preset angle is 5-15°. Gallium nitride is etched to improve the light extraction efficiency of the LED without affecting the performance of the LED device. However, if the preset angle is too large, the spacing between the gallium nitride sublayers 201 will be too large, which will affect the performance of the LED device. If the preset angle is too small, it will limit the light extraction efficiency of the LED, and there will still be some loss of light source.

[0036] Preferably, the preset angle is 10°.

[0037] The specific steps are as follows: a first photoresist is coated on the gallium nitride layer 200, and exposure, development and hardening are performed using a first photomask.

[0038] A second photoresist is coated on the first photoresist, and exposure is performed using a second photomask, followed by development and baking.

[0039] Chlorine and bromine gases are introduced for inductively coupled plasma (ICP) etching, which continues until the substrate reaches 100.

[0040] Remove the photoresist to complete the etching process.

[0041] Step S12: Immerse the etched wafer in an oxidation solution for a first preset time.

[0042] The oxidation solution includes an oxidant, a catalyst, and water. The oxidant is hydrogen peroxide, and the catalyst is Fe3O4 or FeSO4.

[0043] Because gallium nitride has a very high Mohs hardness, the sidewall material of gallium nitride sublayer 201 is first chemically catalyzed to generate gallium oxide with a lower Mohs hardness. Then, the softened sidewall is subjected to cavitation impact by ultrasonication of the roughening solution to form roughening. Therefore, it is necessary to use the Fenton reaction process to generate strong oxidizing functional groups (·OH) that can oxidize the surface of gallium nitride material to generate gallium oxide with a lower Mohs hardness.

[0044] The Fenton reaction process is as follows:

[0045] (1)Fe 2+ +H + +H2O2 - →Fe 3+ +H₂O+·OH

[0046] (2) GaN + 6·OH - →Ga₂O₃ + 3H₂O + N₂↑

[0047] (3)Fe 3+ +H2O2 - →Fe 2+ +H + +·OOH

[0048] Specifically, the concentration of hydrogen peroxide is 2.5%-12.5%. When the concentration of hydrogen peroxide is too high, the reaction is violent and the reaction rate is difficult to control. Gallium oxide will quickly cover the surface of gallium nitride sublayer 201, which is not conducive to the subsequent roughening formation. When the concentration of hydrogen peroxide is too low, the reaction rate is too slow, which affects the process efficiency and reduces the production capacity.

[0049] Preferably, the concentration of hydrogen peroxide is 7.5%.

[0050] Furthermore, the catalyst is FeSO4, with a concentration of 0.2-0.5 mol / L. It should be noted that a lower FeSO4 concentration will directly affect the reaction rate, resulting in an excessively low reaction rate, which in turn reduces process efficiency and thus impacts production capacity.

[0051] Preferably, the concentration of FeSO4 is 0.5 mol / L.

[0052] In addition, the first preset time is 10-15 minutes. If the oxidation time is too long, gallium oxide will quickly cover the surface of the gallium nitride sublayer 201, which is not conducive to the formation of subsequent roughening. If the oxidation time is too short, there will be insufficient gallium oxide formed on the surface, which is not conducive to the uniformity of subsequent roughening.

[0053] Step S13: Place the oxidized wafer into a roughening solution, and sonicate the wafer at a preset frequency and temperature for a second preset time to roughen the sidewalls and surface of the gallium nitride sublayer.

[0054] The process involves utilizing the cavitation bubbles formed in the liquid environment of the roughened solution under ultrasonic action. The high-speed microjets generated by the collapse of these bubbles drive fine particles to impact the sidewalls and surface of the gallium nitride sublayer 201, thus roughening the sidewalls and surface of the gallium nitride sublayer 201. Cavitation bubbles refer to the generation, growth, and collapse of water vapor or other gas bubbles near the interface between the liquid and solid phases when the pressure in a localized area of ​​the liquid phase decreases. As the liquid flows, when the confining pressure suddenly increases, the volume of the cavitation bubble rapidly shrinks until it collapses. Because the collapse process of the cavitation bubble is extremely short (on the microsecond scale), it generates extremely high instantaneous pressure and high-speed microjets in a localized area. Fine particles on or near the cavitation bubble move with the indentation of the upper bubble wall. The high-speed microjets generated by the collapse of the cavitation bubble drive the fine particles to impact the wall surface, thus roughening the sidewalls and surface of the gallium nitride sublayer 201.

[0055] Specifically, the roughening solution includes silicon oxide and aluminum oxide, with silicon oxide concentration of 2%-4% and aluminum oxide concentration of 3%-5%. It should be noted that the ratio of silicon oxide to aluminum oxide is used to roughen the gallium nitride sublayer 201, thereby achieving uniform roughening of the surface and sidewalls of the gallium nitride sublayer 201.

[0056] Preferably, the concentration of silicon oxide is 2% and the concentration of aluminum oxide is 4%. When the ratio of silicon oxide to aluminum oxide concentration is not within the current range, the different depths and positions of the gallium nitride sublayer 201 on the sidewalls and surface will cause differences in the roughness of the sidewalls and surface of the gallium nitride sublayer 201, thereby affecting the light output efficiency of the LED.

[0057] Meanwhile, the particle size of silicon oxide and aluminum oxide is 0.01-0.1μm to form a coarsened and uniform gallium nitride sublayer 201. When the particle size is too small, the coarsening degree of gallium nitride sublayer 201 is insufficient, and large total internal reflection will still occur at the interface, reducing the light output efficiency of the LED. When the particle size is too large, the silicon oxide and aluminum oxide particles will severely damage the gallium nitride sublayer 201, resulting in uneven coarsening, excessive roughness, and even wear down the entire wafer.

[0058] Preferably, the particle size of both silicon oxide and aluminum oxide is 0.05 μm.

[0059] In addition, the preset frequency is 20-60kHz to form a coarsened and uniform gallium nitride sublayer 201. When the preset frequency is too low, the coarsening degree of gallium nitride sublayer 201 is insufficient, and large total internal reflection will still occur at the interface, reducing the light output efficiency of the LED. When the preset frequency is too high, it will severely damage the gallium nitride sublayer 201, resulting in uneven coarsening, excessive roughness, and may even wear down the entire wafer.

[0060] Preferably, the preset frequency is 30kHz.

[0061] In addition, the gallium nitride sublayer 201 is roughened by ultrasonic treatment at a preset temperature for a second preset time. The preset temperature is 25-35℃. Temperature affects the progress of the roughening reaction. When the preset temperature is too low, the roughening reaction rate is too slow, which affects the process efficiency and reduces the production capacity. When the preset temperature is too high, the roughening reaction rate is too fast, the roughening is more uneven, and the surface and sidewall roughness of the gallium nitride sublayer 201 are too large, which affects the light output efficiency of the LED.

[0062] Preferably, the preset temperature is 29℃.

[0063] The second preset time is 15-25 min. The second preset time will affect the degree of roughening reaction. The shorter the second preset time, the lower the roughening degree of gallium nitride sublayer 201.

[0064] Preferably, the second preset time is 20 minutes.

[0065] It should be noted that this roughening method combines chemical catalysis and physical impact technology to roughen the sidewalls and surface of the gallium nitride sublayer 201, thereby forming a gallium nitride sublayer 201 with uniform roughness and good surface roughness, which improves the light extraction efficiency and yield of LEDs.

[0066] In addition, after roughening the wafer, it needs to be removed and cleaned.

[0067] Compared to existing technologies, the gallium nitride (GaN) layer roughening method provided in this embodiment has the following advantages: The GaN layer is etched at a preset angle with a preset distance until the substrate is exposed, forming several GaN sublayers. The increased sidewalls improve LED light extraction efficiency. The etched wafer is then placed in an oxidation solution for a first preset time to oxidize and soften the surface and sidewalls of the GaN sublayers. The oxidized wafer is then placed in a roughening solution and ultrasonically subjected to a preset frequency and temperature while maintaining a second preset temperature. A time-dependent method is used to roughen the sidewalls and surface of the gallium nitride (GaN) sublayer. This is achieved by forming cavitation bubbles in a roughening liquid within an ultrasonic environment. These bubbles carry particles in the roughening liquid that impact the sidewalls and surface of the GaN sublayer, thus roughening the surface. This roughening method is simple and effective, combining chemical catalysis with physical impact technology to form a uniformly roughened GaN sublayer with good surface roughness. The surface and sidewalls of the GaN sublayer remain undamaged, further improving LED light extraction efficiency. This solves the common technical problem of poor surface roughening quality and damage in GaN layers.

[0068] Example 2

[0069] The second embodiment of the present invention provides a method for roughening a gallium nitride layer. The difference between the gallium nitride layer roughening method in this embodiment and the gallium nitride layer roughening method in the first embodiment is as follows:

[0070] Steps S12 and S13 are combined into one step, in which the etched wafer is placed in an oxide roughening solution and reacted at a preset frequency and temperature for a third preset time to roughen the sidewalls and surface of the gallium nitride sublayer.

[0071] The oxidative roughening solution includes an oxidant, a catalyst, water, silicon dioxide, and aluminum oxide. The oxidant is hydrogen peroxide, the catalyst is FeSO4, the concentration of hydrogen peroxide is 2%-10%, the concentration of FeSO4 is 0.2-0.5 mol / L, the concentration of silicon dioxide is 2%-4%, and the concentration of aluminum oxide is 3%-5%. The preset frequency is 20-60 kHz, and the preset temperature is 25-35℃.

[0072] It should be noted that by employing both chemical catalysis and physical roughening techniques simultaneously, the two processes complement each other and will improve the efficiency of gallium nitride sublayer roughening.

[0073] Preferably, the concentration of hydrogen peroxide is 5%. Since the roughening solution is carried out simultaneously, it will catalyze the oxidation reaction and improve the reaction activity. The concentration of hydrogen peroxide does not need to reach 7.5% in Example 1 to complete the oxidation of the sidewalls and surface of the gallium nitride sublayer.

[0074] In addition, the concentration of FeSO4 is 0.5 mol / L, the concentration of silicon oxide is 2%, the concentration of aluminum oxide is 4%, the particle size of silicon oxide and aluminum oxide is 0.05 μm, the preset frequency is 30 kHz, and the preset temperature is 29 °C, in order to achieve the optimal roughening conditions and form a gallium nitride sublayer with uniform roughness.

[0075] In addition, the third preset temperature is 10-20 min. In this process, chemical catalysis and physical roughening complement each other, which will improve the efficiency of gallium nitride sublayer roughening and reduce the roughening time.

[0076] Preferably, the third preset temperature is 15 min.

[0077] Compared to existing technologies, the gallium nitride (GaN) layer roughening method provided in this embodiment has the following advantages: By integrating the oxidation and roughening steps and simultaneously employing chemical catalysis and physical roughening techniques, the chemical catalysis and physical roughening complement each other, thereby improving the efficiency of GaN sublayer roughening, reducing roughening time, and increasing production efficiency. This roughening method is simple and effective, combining chemical catalysis and physical impact techniques to form a uniformly roughened GaN sublayer with good roughness. The surface and sidewalls of the GaN sublayer are undamaged, further improving LED light extraction efficiency, thus solving the common technical problem of poor surface roughening quality and damage in GaN layers.

[0078] Example 3

[0079] The third embodiment of the present invention provides a method for roughening a gallium nitride layer. The difference between the gallium nitride layer roughening method in this embodiment and the gallium nitride layer roughening method in the first embodiment is as follows:

[0080] The concentration of hydrogen peroxide is 5%.

[0081] Example 4

[0082] The fourth embodiment of the present invention provides a method for roughening a gallium nitride layer. The method for roughening a gallium nitride layer in this embodiment differs from the method for roughening a gallium nitride layer in the first embodiment in that:

[0083] The concentration of hydrogen peroxide is 2.5%.

[0084] Example 5

[0085] The fifth embodiment of the present invention provides a method for roughening a gallium nitride layer. The method for roughening a gallium nitride layer in this embodiment differs from the method for roughening a gallium nitride layer in the first embodiment in that:

[0086] The concentration of hydrogen peroxide is 10%.

[0087] Example 6

[0088] The sixth embodiment of the present invention provides a method for roughening a gallium nitride layer. The method for roughening a gallium nitride layer in this embodiment differs from the method for roughening a gallium nitride layer in the first embodiment in that:

[0089] The concentration of hydrogen peroxide is 12.5%.

[0090] Example 7

[0091] The seventh embodiment of the present invention provides a method for roughening a gallium nitride layer. The method for roughening a gallium nitride layer in this embodiment differs from the method for roughening a gallium nitride layer in the first embodiment in that:

[0092] The concentration of FeSO4 is 0.35 mol / L.

[0093] Example 8

[0094] The eighth embodiment of the present invention provides a method for roughening a gallium nitride layer. The method for roughening a gallium nitride layer in this embodiment differs from the method for roughening a gallium nitride layer in the first embodiment in that:

[0095] The concentration of FeSO4 is 0.2 mol / L.

[0096] Example 9

[0097] The ninth embodiment of the present invention provides a method for roughening a gallium nitride layer. The method for roughening a gallium nitride layer in this embodiment differs from the method for roughening a gallium nitride layer in the first embodiment in that:

[0098] The concentration of silicon dioxide is 2%, and the concentration of aluminum oxide is 3%.

[0099] Example 10

[0100] The tenth embodiment of the present invention provides a method for roughening a gallium nitride layer. The method for roughening a gallium nitride layer in this embodiment differs from the method for roughening a gallium nitride layer in the first embodiment in that:

[0101] The concentration of silicon dioxide is 3%, and the concentration of aluminum oxide is 4%.

[0102] Example 11

[0103] The eleventh embodiment of the present invention provides a method for roughening a gallium nitride layer. The method for roughening a gallium nitride layer in this embodiment differs from the method for roughening a gallium nitride layer in the first embodiment in that:

[0104] The concentration of silicon dioxide is 4%, and the concentration of aluminum oxide is 5%.

[0105] Example 12

[0106] The twelfth embodiment of the present invention provides a method for roughening a gallium nitride layer. The method for roughening a gallium nitride layer in this embodiment differs from the method for roughening a gallium nitride layer in the first embodiment in that:

[0107] The concentration of silicon dioxide is 4%, and the concentration of aluminum oxide is 3%.

[0108] Example 13

[0109] The thirteenth embodiment of the present invention provides a method for roughening a gallium nitride layer. The method for roughening a gallium nitride layer in this embodiment differs from the method for roughening a gallium nitride layer in the first embodiment in that:

[0110] The particle size of both the silicon oxide and the aluminum oxide is 0.01 μm.

[0111] Example 14

[0112] The fourteenth embodiment of the present invention provides a method for roughening a gallium nitride layer. The method for roughening a gallium nitride layer in this embodiment differs from the method for roughening a gallium nitride layer in the first embodiment in that:

[0113] The particle size of both the silicon oxide and the aluminum oxide is 0.1 μm.

[0114] Example 15

[0115] The fifteenth embodiment of the present invention provides a method for roughening a gallium nitride layer. The method for roughening a gallium nitride layer in this embodiment differs from the method for roughening a gallium nitride layer in the first embodiment in that:

[0116] The preset frequency is 20kHz.

[0117] Example 16

[0118] The sixteenth embodiment of the present invention provides a method for roughening a gallium nitride layer. The method for roughening a gallium nitride layer in this embodiment differs from the method for roughening a gallium nitride layer in the first embodiment in that:

[0119] The preset frequency is 40kHz.

[0120] Example 17

[0121] The seventeenth embodiment of the present invention provides a method for roughening a gallium nitride layer. The method for roughening a gallium nitride layer in this embodiment differs from the method for roughening a gallium nitride layer in the first embodiment in that:

[0122] The preset angle is 5°.

[0123] Example 18

[0124] The eighteenth embodiment of the present invention provides a method for roughening a gallium nitride layer. The method for roughening a gallium nitride layer in this embodiment differs from the method for roughening a gallium nitride layer in the first embodiment in that:

[0125] The preset angle is 15°.

[0126] Comparative Example 1

[0127] The first comparative example of this invention provides a method for roughening a gallium nitride layer. The difference between the gallium nitride layer roughening method in this comparative example and the gallium nitride layer roughening method in the first embodiment is as follows:

[0128] Instead of etching at a preset angle, the gallium nitride layer is directly oxidized and roughened.

[0129] Comparative Example 2

[0130] The blank control group did not undergo the preset angle etching and oxidation roughening steps.

[0131] Please refer to Table 1 below, which shows the parameters corresponding to Embodiment 1, Embodiment 3 to Embodiment 22 of the present invention.

[0132] Table 1

[0133]

[0134]

[0135] It should be noted that the epitaxial wafers of Embodiments 1, 3 to 18 of the present invention were manufactured using the same process conditions.

[0136] As can be seen from the data of Examples 1, 3 to 18 compared to Comparative Example 2, surface roughening can effectively improve the light extraction efficiency of LEDs.

[0137] Based on the data from Examples 1, 3 to 6, it can be seen that when the concentration of hydrogen peroxide is too high, the roughness and uniformity are poor. Due to the high concentration, the reaction is violent and the reaction rate is difficult to control. Gallium oxide will quickly cover the surface of the gallium nitride sublayer, which is not conducive to the subsequent roughening formation. When the concentration of hydrogen peroxide is too low, it will not affect the roughness and uniformity, but the reaction time will be too long, which will affect the process efficiency and reduce the production capacity.

[0138] Based on the data from Examples 1, 7, and 8, it can be seen that the catalyst has little effect on roughness and uniformity. However, the lower the concentration of FeSO4, the more directly it will affect the reaction rate, resulting in an excessively low reaction rate, which will affect the efficiency of the process and thus the production capacity.

[0139] Based on the data from Examples 1, 9 to 12, it can be seen that when the ratio and concentration of silicon oxide and aluminum oxide are not within the current range, the different depths and positions of the gallium nitride sublayers on the sidewalls and surfaces will cause differences in the roughness of the gallium nitride sublayer sidewalls and surfaces, resulting in poorer uniformity of roughness and affecting the light extraction efficiency of the LED.

[0140] Based on the data from Examples 1, 13, and 14, it can be seen that when the particle size is too small, the coarsening degree of the gallium nitride sublayer is insufficient, and the roughness is low, which affects the light output efficiency of the LED. When the particle size is too large, the silicon oxide and aluminum oxide particles cause serious damage to the gallium nitride sublayer, resulting in uneven coarsening and no significant improvement in light output efficiency.

[0141] Based on the data from Examples 1, 15, and 16, it can be seen that when the preset frequency is too low, the coarsening degree of the gallium nitride sublayer is insufficient, affecting the light output efficiency of the LED. When the preset frequency is too high, it causes severe damage to the gallium nitride sublayer and uneven coarsening.

[0142] Based on the data from Examples 1, 17, and 18, and Comparative Example 1, it can be seen that when the preset angle is too large, the spacing between gallium nitride sublayers is too large, which will affect the performance of the LED device. When the preset angle is too small, it limits the light output efficiency of the LED.

[0143] In summary, by etching the gallium nitride layer to form several gallium nitride sublayers, and then combining chemical catalysis and physical impact techniques to roughen the sidewalls and surface of the gallium nitride sublayers, a uniformly roughened gallium nitride sublayer with good surface roughness is formed, which greatly improves the light extraction efficiency and yield of LEDs.

[0144] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0145] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A method for roughening a gallium nitride layer, characterized in that, The method for roughening the gallium nitride layer includes: A wafer to be roughened is provided, the wafer including a substrate and a gallium nitride layer disposed on the substrate; The gallium nitride layer is etched at a preset angle at a preset distance until the substrate is exposed, so as to form a plurality of gallium nitride sublayers; The etched wafer is placed in an oxidation solution for oxidation for a first preset time; The oxidized wafer is placed in a roughening solution and ultrasonicated at a preset frequency and temperature for a second preset time to roughen the sidewalls and surface of the gallium nitride sublayer.

2. The method for roughening a gallium nitride layer according to claim 1, characterized in that, The oxidation solution includes an oxidant, a catalyst, and water. The oxidant is hydrogen peroxide, and the catalyst is Fe3O4 or FeSO4.

3. The method for roughening a gallium nitride layer according to claim 2, characterized in that, The concentration of hydrogen peroxide is 2.5%-12.5%.

4. The method for roughening a gallium nitride layer according to claim 2, characterized in that, The concentration of FeSO4 is 0.2-0.5 mol / L.

5. The method for roughening a gallium nitride layer according to claim 1, characterized in that, The roughening solution comprises silicon oxide and aluminum oxide, wherein the concentration of silicon oxide is 2%-4% and the concentration of aluminum oxide is 3%-5%.

6. The method for roughening a gallium nitride layer according to claim 5, characterized in that, The particle size of both the silicon oxide and the aluminum oxide is 0.01-0.1 μm.

7. The method for roughening a gallium nitride layer according to claim 1, characterized in that, The preset angle is 5-15°.

8. The method for roughening a gallium nitride layer according to claim 1, characterized in that, The first preset time is 10-15 minutes, and the second preset time is 15-25 minutes.

9. The method for roughening a gallium nitride layer according to claim 1, characterized in that, The preset frequency is 20-60 kHz, and the preset temperature is 25-35℃.

Images