Etching method of transparent conductive material layer, LED chip and manufacturing method of LED chip

Abstract

The invention provides an etching method of a transparent conductive material layer, an LED chip and a manufacturing method of the LED chip. The etching method of the transparent conductive material layer comprises the following steps: sequentially coating photoresist, exposing, developing and hardening for the first time on the surface of the transparent conductive material layer to obtain a first photoresist layer with a first preset pattern; etching the transparent conductive material layer for n times by taking the first photoresist layer as a mask to form a transparent conductive layer, n being greater than or equal to 2, and n being a positive integer; the first solution is added in the etching solution, so that the surface tension of the etching solution is gradually reduced, the wettability of the etching solution is improved, etching is more uniform, the etching angle is gentle, and burrs are prevented from being generated on the edge after etching. The manufacturing method of the LED chip adopts the etching method, and the manufacturing method of the LED chip is adopted on the LED chip.

Description

Technical Field

[0001] The present invention relates to the technical field of light emitting diodes, and more particularly to an etching method for a transparent conductive material layer, an LED chip and a manufacturing method thereof. Background Art

[0002] A light-emitting diode (LED) is a semiconductor device that converts electrical energy into light. Due to its many advantages, LED chips are widely used in nightscape decoration, traffic signal indicators, interior lighting, automotive lighting, large-screen full-color displays, mobile phone backlighting, and other fields. LED chips are mainly categorized into top-mounted, flip-chip, horizontal, and vertical structures. Regardless of the chip structure, a transparent conductive layer is typically required to improve the LED chip's performance, such as current expansion and light extraction efficiency.

[0003] During the LED chip manufacturing process, after evaporating or sputtering a transparent conductive material layer on the epitaxial wafer surface, etching is typically required to form a pre-defined transparent conductive layer. Etching methods primarily include dry etching and wet etching. Dry etching can easily damage the underlying film layer, affecting the chip's optoelectronic performance. Furthermore, the high equipment cost makes it unsuitable for large-scale LED chip production. Wet etching, on the other hand, offers advantages such as ease of operation and high production efficiency, and has gradually become the mainstream etching process for transparent conductive layers.

[0004] However, the current wet etching process still has some defects. Wet etching is isotropic etching and usually requires the use of a highly corrosive etching solution. During the etching process, the transparent conductive material layer reacts violently with the etching solution, making it difficult to control the etching angle. For example, the etching angle of the formed transparent conductive layer is too large, affecting the optoelectronic performance of the LED chip. In addition, the transparent conductive material layer is usually wet-etched with an acidic solution. Strong acidic etching solutions have high surface tension (such as pure HCl), which makes it difficult to infiltrate the hydrophobic transparent conductive layer surface, resulting in uneven etching and burrs on the etching edges, which can easily lead to leakage risks in the LED chip. Summary of the Invention

[0005] In view of this, the present invention provides an etching method for a transparent conductive material layer, an LED chip and a manufacturing method thereof, so as to improve etching uniformity.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A method for etching a transparent conductive material layer, comprising:

[0008] Providing a transparent conductive material layer to be etched;

[0009] Applying photoresist, exposing, developing and hardening the surface of the transparent conductive material layer in sequence to obtain a first photoresist layer having a first preset pattern;

[0010] Using the first photoresist layer as a mask, etching the transparent conductive material layer n times to form a transparent conductive layer, where n is greater than or equal to 2 and n is a positive integer;

[0011] The etching solution for etching the transparent conductive material layer includes HCl, FeCl3, H2O, and a first solution;

[0012] From the first etching to the nth etching, the weight percentage of the first solution in the etching solution increases successively, so that the surface tension of the etching solution decreases successively.

[0013] Optionally, from the first etching to the nth etching, the temperature of the etching solution increases successively.

[0014] Optionally, the etching time is gradually reduced from the first etching to the nth etching.

[0015] Optionally, the first solution includes one or more of isopropyl alcohol, methanol, ethylene glycol, propylene glycol methyl ether and acetone.

[0016] Optionally, in the n etchings, a cleaning step is provided after each etching is completed;

[0017] The cleaning step includes sequentially rinsing the etched semi-finished product with deionized water, replacing it with an ethanol solution, replacing it with an isopropanol solution, and drying it with a supercritical inert gas;

[0018] The cleaning time of each cleaning step is 1 min to 10 min, including the endpoint value.

[0019] Optionally, the drying using a supercritical inert gas includes using one or more of supercritical CO2, N2, Ar and He.

[0020] Optionally, in n etchings, the weight percentage of the first solution in the i-th etching to the etching solution is W(i), 1<i≤n; wherein 1.1*W(i-1)≤W(i)≤2.5*W(i-1);

[0021] During the first etching, the weight percentage of the first solution in the etching solution is greater than or equal to 20%.

[0022] Optionally, in n etchings, the temperature of the etching solution in the i-th etching is T(i), 1<i≤n;

[0023] Among them, 1.1*T(i-1)≤T(i)≤1.5*T(i-1).

[0024] Optionally, in n etchings, the etching time of the i-th etching is t(i), 1<i≤n; 0.5*t(i-1)≤t(i)≤0.8*t(i-1).

[0025] Optionally, in n etchings, the difference in surface tension of the etching solution between two adjacent etchings is not greater than 10 mN / m;

[0026] In the n etchings, the etching rate of each etching is less than or equal to 90 nm / min.

[0027] The present invention also provides a method for manufacturing an LED chip, comprising:

[0028] providing a substrate;

[0029] Growing an epitaxial stack on one side surface of the substrate; the epitaxial stack includes a first-type semiconductor layer, an active layer, and a second-type semiconductor layer stacked in sequence in a direction away from the substrate;

[0030] forming a transparent conductive material layer on a surface of the epitaxial stack facing away from the substrate;

[0031] Using any one of the above-mentioned methods for etching a transparent conductive material layer, etching the transparent conductive material layer to form a transparent conductive layer;

[0032] manufacturing a first electrode, wherein the first electrode is electrically connected to the first-type semiconductor layer;

[0033] A second electrode is manufactured, wherein the second electrode is electrically connected to the second-type semiconductor layer.

[0034] Optionally, after the transparent conductive layer is formed, a suspended structure is formed around the first photoresist layer;

[0035] The transparent conductive layer includes a contact layer and a conductive layer stacked in sequence in a direction away from the substrate;

[0036] The distance between the edge line on each side of the contact layer and the edge line on the same side of the first photoresist layer is L1, and L1 is ≥ 3.5 μm;

[0037] The distance between the edge line on each side of the conductive layer and the edge line on the same side of the first photoresist layer is L2, and L2 is ≥ 4 μm;

[0038] After forming the transparent conductive layer and before forming the first electrode and the second electrode, the following steps are also included:

[0039] Performing a second hardening process on the first photoresist layer to form a second photoresist layer having a second predetermined pattern; wherein the temperature of the second hardening process is 1.1 to 1.5 times, inclusive, of the temperature of the first hardening process;

[0040] etching the epitaxial stack using the second photoresist layer as a mask to expose a portion of the surface of the first-type semiconductor layer;

[0041] The first electrode is disposed on the exposed surface of the first-type semiconductor layer.

[0042] The present invention further provides an LED chip, which is manufactured using any of the above-mentioned methods for manufacturing an LED chip.

[0043] Compared with the existing technology, the technical solution provided by the present invention has at least the following advantages:

[0044] 1. This method for etching a transparent conductive material layer involves performing the etching step of the transparent conductive material layer multiple times to avoid difficulty controlling the etching angle due to the intense reaction between the transparent conductive material layer and the etching solution. This allows for better adjustment and control of the etching angle of the transparent conductive layer. The etching solution comprises HCl, FeCl3, H2O, and a first solution, wherein the first solution is capable of reducing the surface tension of the etching solution, allowing the etching solution to better infiltrate the surface of the transparent conductive material layer, resulting in more uniform etching and avoiding burrs at the edges after etching. Furthermore, from the first etching step to the nth etching step, the weight percentage of the first solution in the etching solution increases successively, thereby gradually reducing the surface tension of the etching solution, improving the wettability of the etching solution, further achieving more uniform etching, and a gentler etching angle.

[0045] 2. From the first etching to the nth etching, the temperature of the etching solution is gradually increased, further reducing the surface tension of the etching solution, while also being able to control the etching rate of the transparent conductive material layer.

[0046] 3. From the first etching to the nth etching, the etching time is gradually reduced. Combined with the temperature change of the etching solution, the etching amount in each etching process can be controlled, which also helps to better control the etching angle and etching uniformity of the transparent conductive layer.

[0047] 4. A cleaning step is set after each etching is completed, and the cleaning step includes deionized water rinsing, ethanol solution replacement, isopropanol solution replacement and drying steps using supercritical inert gas in sequence, wherein the surface tension of the ethanol solution and the isopropanol solution is smaller than that of the etching solution, the surface tension of isopropanol is smaller than that of ethanol, and a liquid with low surface tension is used for solution replacement, and a solution with a step-by-step decrease in surface tension is used to sequentially replace the solution to avoid different surface tensions in different areas, resulting in local over-etching and affecting the uniformity of etching.

[0048] Specifically, after each etching is completed, the etching solution has poor wettability due to its large surface tension, forming droplets or local residues in the transparent conductive material layer, causing continuous reaction in certain areas and initiating over-etching. Ethanol and isopropanol solutions have low surface tension and stronger liquid fluidity, and can quickly and evenly cover the entire surface of the transparent conductive material layer, as well as microstructures (such as grooves or pores at the micron or nanometer scale), quickly replacing the residual etching solution, reducing local reaction time, and avoiding local over-etching caused by etching solution retention. Moreover, in the microstructure, low surface tension liquids can more easily penetrate into narrow areas through capillary action, remove etching solution residues, and prevent over-etching of hidden areas; therefore, after using ethanol solution for solution replacement, using isopropanol with even lower surface tension for solution replacement can further remove etching solution residues in hidden areas that the ethanol solution failed to remove.

[0049] 5. In n etchings, the weight percentage of the first solution in the etching solution of the latter etching is 1.1 to 2.5 times that of the previous etching. If the multiple is less than 1.1 times, the surface tension change is too small and the change before and after is not obvious. If the multiple is greater than 2.5 times, the etching rate will be too low. Therefore, this application sets the coefficient of change before and after to 1.1 to 2.5 times, so that the change in surface tension and the etching rate are within a reasonable range, and the etching is more uniform.

[0050] During the first etching, if the weight percentage of the first solution in the etching solution is less than 20%, the surface tension of the etching solution does not change significantly, and the surface of the transparent conductive material layer cannot be better wetted. Therefore, during the first etching, the weight percentage of the first solution in the etching solution is set to be greater than or equal to 20%, thereby improving etching uniformity.

[0051] 6. During n etching cycles, the temperature of the etching solution in the subsequent etching cycle is 1.1 to 1.5 times that of the previous etching cycle. If the temperature is less than 1.1 times, the surface tension change is too small, and the change is not obvious. If the temperature is greater than 1.5 times, the etching rate is too high. Therefore, this application sets the temperature change coefficient to 1.1 to 1.5 times, so that the surface tension change and etching rate are within a reasonable range, and the etching is more uniform.

[0052] 7. In n etchings, the subsequent etching time is 0.5 to 0.8 times that of the previous one. If it is less than 0.5 times, the etching amount is too small. If it is more than 0.8 times, the etching amount is too large, affecting etching uniformity. Therefore, this application sets the time variation coefficient between 0.5 and 0.8 times, so that the etching amount of each time is within a reasonable range and the etching is more uniform.

[0053] 8. If the difference in surface tension between the etching solution between two adjacent etchings is greater than 10 mN / m, etching uniformity will deteriorate. If the etching rate for each etching is greater than 90 nm / min during n etchings, the etching rate is too fast, etching uniformity is poor, and over-etching is likely to occur. Therefore, the present application sets the difference in surface tension between the etching solution between two adjacent etchings to be no greater than 10 mN / m, and the etching rate for each etching is less than or equal to 90 nm / min, thereby improving etching uniformity.

[0054] 9. The method for manufacturing an LED chip adopts any of the above-mentioned etching methods for a transparent conductive material layer, thus having any of the above-mentioned beneficial effects.

[0055] 10. The first photoresist layer is hardened a second time to form a second photoresist layer having a second preset pattern, so that MESA etching can be performed using the second photoresist layer as a mask to expose a portion of the surface of the first-type semiconductor layer. The transparent conductive material layer etching and MESA etching are placed in the same process step, saving photolithography process steps and simplifying the manufacturing process. After the transparent conductive layer is formed, a suspended structure is formed around the first photoresist layer, and the distance from the edge line on each side of the contact layer to the edge line on the same side of the first photoresist layer is set to L1, L1 ≥ 3.5 μm; the distance from the edge line on each side of the conductive layer to the edge line on the same side of the first photoresist layer is set to L2, L2 ≥ 4 μm, to prevent the edge of the transparent conductive layer from contacting the MESA table, which may cause leakage of the LED chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0057] Figure 1-4 This is a schematic diagram of the etching process of the transparent conductive material layer in an embodiment of the present application;

[0058] Figure 5-12 Schematic diagram of the process of manufacturing the LED chip in the embodiment of the present application.

[0059] Reference numerals:

[0060] Transparent conductive material layer 1; first photoresist layer 2; transparent conductive layer 3; contact layer 31; conductive layer 32; substrate 4; first type semiconductor layer 5; active layer 6; second type semiconductor layer 7; first electrode 8; second electrode 9; second photoresist layer 10; passivation layer 11. DETAILED DESCRIPTION

[0061] To make the content of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0062] In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0063] Secondly, this application is described in detail with reference to schematic diagrams. When describing the embodiments of this application, for ease of explanation, cross-sectional views of device structures may be partially enlarged and not to scale. Furthermore, these schematic diagrams are merely illustrative and should not limit the scope of protection of this application. Furthermore, in actual production, three-dimensional dimensions, including length, width, and depth, should be included.

[0064] The present application provides a method for etching a transparent conductive material layer 1, which comprises:

[0065] S01: providing a transparent conductive material layer 1 to be etched, Figure 1 A schematic diagram of the structure of a transparent conductive material layer is shown. Optionally, the transparent conductive material layer 1 may include one or more of ITO, AZO, GZO, FTO, ATO, IZO, IGO, IGZO, IWO, IMO, etc. In the embodiments of this application, ITO is used as an example. Optionally, the transparent conductive material layer 1 provided may be produced by sputtering.

[0066] S02: Figure 2 -3, Figure 2 Schematic diagram of the structure of applying photoresist on the transparent conductive material layer 1. Figure 3 The schematic diagram shows a structure for forming a first photoresist layer 2 on a transparent conductive material layer 1. The surface of the transparent conductive material layer 1 is sequentially subjected to photoresist coating, exposure, development, and a first hardening process to obtain a first photoresist layer 2 having a first predetermined pattern. Optionally, the first hardening process is performed at a temperature of 0°C to 105°C, inclusive.

[0067] S03: Using the first photoresist layer 2 as a mask, the transparent conductive material layer 1 is etched n times to form a transparent conductive layer 3, where n ≥ 2 and n is a positive integer. The etching solution for etching the transparent conductive material layer 1 includes HCl, FeCl3, H2O, and the first solution. From the first etching to the n-th etching, the weight percentage of the first solution in the etching solution is gradually increased to gradually reduce the surface tension of the etching solution. Prior to etching the transparent conductive material layer 1 n times, the area to be etched may be subjected to a plasma cleaning treatment. Figure 4 Schematic diagram of the structure of the transparent conductive layer 3 formed after n etchings.

[0068] In order to avoid the difficulty in controlling the etching angle due to the violent reaction between the transparent conductive material layer 1 and the etching solution, the etching step of the transparent conductive material layer 1 is carried out in multiple steps, which can better adjust and control the etching angle of the transparent conductive layer 3. The etching angle is Figure 4 The θ angle in the etching solution is 0.044°. The etching solution includes HCl, FeCl3, H2O, and a first solution, wherein the first solution can reduce the surface tension of the etching solution, so that the etching solution can better infiltrate the surface of the transparent conductive material layer 1, the etching is more uniform, and burrs are avoided at the edge after etching; from the first etching to the nth etching, the weight percentage of the first solution in the etching solution increases successively, so that the surface tension of the etching solution is gradually reduced, the wettability of the etching solution is improved, and the etching is further more uniform and the etching angle is relatively gentle.

[0069] Preferably, the first solution includes one or more of isopropyl alcohol, methanol, ethylene glycol, propylene glycol methyl ether and acetone. In the embodiments of the present application, isopropyl alcohol is used as an example. Wherein, isopropyl alcohol, through its amphiphilic molecular structure, interferes with the hydrogen bond network between water molecules in the etching solution and forms a monolayer of hydrophobic groups arranged on the surface of the solution, thereby significantly reducing surface tension. This characteristic enables it to effectively improve wettability in the etching solution and ensure etching uniformity and process stability. The hydroxyl group of isopropyl alcohol forms hydrogen bonds with water, destroys the strong hydrogen bond structure between the original water molecules and reduces the intermolecular force, thereby reducing surface tension. The non-polar isopropyl group of isopropyl alcohol tends to migrate to the surface of the solution (hydrophobic end towards the air), occupies surface position, reduces the density of surface water molecules, and further weakens the surface tension of the etching solution.

[0070] Further preferably, in n etchings, the weight percentage of the first solution in the i-th etching to the etching solution is W(i), 1<i≤n; wherein 1.1*W(i-1)≤W(i)≤2.5*W(i-1). During the first etching, the weight percentage of the first solution to the etching solution is greater than or equal to 20%.

[0071] That is, in two adjacent etchings of n times, the weight percentage of the first solution in the latter etching in the etching solution is 1.1 times to 2.5 times (including the end points) the weight percentage of the first solution in the previous etching in the etching solution. For example, the weight percentage of the first solution in the first etching in the etching solution is W(1), and W(1) is greater than or equal to 20%. W(2) = (1.1 to 2.5) * W1, W(3) = (1.1 to 2.5) * W(2), W(4) = (1.1 to 2.5) * W(3), ..., W(n) = (1.1 to 2.5) * W(n-1).

[0072] In n etchings, the weight percentage of the first solution in the etching solution of the latter etching is 1.1 to 2.5 times that of the previous etching. If the multiple is less than 1.1 times, the surface tension change is too small, and the change before and after is not obvious. If the multiple is greater than 2.5 times, the etching rate will be too low. Therefore, the present application sets the coefficient of change before and after to 1.1 to 2.5 times, so that the change in surface tension and the etching rate are within a reasonable range, and the etching is more uniform. During the first etching, if the weight percentage of the first solution in the etching solution is less than 20%, the change in the surface tension of the etching solution is not obvious, and the effect of better wetting the surface of the transparent conductive material layer 1 cannot be achieved; therefore, during the first etching, the weight percentage of the first solution in the etching solution is greater than or equal to 20%, thereby improving the etching uniformity.

[0073] Optionally, in a specific embodiment, from the first etching to the nth etching, the surface tension of the etching solution gradually decreases from 38 mN / m to 22 mN / m.

[0074] Based on the previous embodiment, in a preferred embodiment, in step S03, the temperature of the etching solution is gradually increased from the first etching to the nth etching. This configuration further reduces the surface tension of the etching solution while also controlling the etching rate of the transparent conductive material layer 1. Optionally, in a specific embodiment, the difference in etching rate between the n etchings is controlled by gradually increasing the temperature to be less than 20%.

[0075] Preferably, in n etchings, the temperature of the etching solution for the i-th etching is T(i), 1<i≤n. Among them, 1.1*T(i-1)≤T(i)≤1.5*T(i-1). That is, in two adjacent etchings of n etchings, the temperature of the etching solution for the latter etching is 1.1 times to 1.5 times (including the endpoint values) the temperature of the etching solution for the previous etching. For example, the temperature of the etching solution for the first etching is T(1), T(2)=(1.1~1.5)*T1, T(3)(1.1~1.5)*T(2), T(4)=(1.1~1.5)*T(3), ..., T(n)=(1.1~1.5)*T(n-1).

[0076] In n etching cycles, the temperature of the etching solution in the subsequent etching is 1.1 to 1.5 times that of the previous etching. If the multiple is less than 1.1, the surface tension change is too small, and the change before and after is not obvious; if the multiple is greater than 1.5, the etching rate is too high. Therefore, this application sets the temperature change coefficient between 1.1 and 1.5 times, so that the change in surface tension and the etching rate are within a reasonable range, and the etching is more uniform.

[0077] Preferably, the etching solution temperature T(i) for the n-th etching is in the range of 25°C ≤ T(i) ≤ 80°C. Further preferably, the etching solution temperature for the first etching is not higher than 50°C, and the etching solution temperature for the n-th etching is not higher than 80°C. That is, the etching solution temperature for each etching is within the range of 25°C ≤ T(i) ≤ 80°C, and the etching solution temperature for the first etching is not higher than 50°C, and the etching solution temperature for the n-th etching is not higher than 80°C.

[0078] Based on the previous embodiment, in a preferred embodiment, in step S03, the etching time is gradually reduced from the first etching to the nth etching. This setting, combined with the temperature change of the etching solution, can control the etching amount during each etching process, which helps to better control the etching angle and etching uniformity of the transparent conductive layer 3.

[0079] Preferably, in n etchings, the etching time of the i-th etching is t(i), 1<i≤n;0.5t(i-1)≤t(i)≤0.8*t(i-1). That is, in two adjacent etchings of n etchings, the etching time of the latter etching is 0.5 times to 0.8 times (including the endpoint values) the etching time of the previous etching. For example, the time of the first etching is t(1). t(2)=(0.5~0.8)*t1, t(3)=(0.5~0.8)*t(2), t(4)=(0.5~0.8)*t(3), ..., t(n)=(0.5~0.8)*t(n-1).

[0080] In n etching cycles, the subsequent etching time is 0.5 to 0.8 times that of the previous one. If it is less than 0.5 times, the etching amount is too small; if it is more than 0.8 times, the etching amount is too large, affecting etching uniformity. Therefore, this application sets the time variation coefficient between 0.5 and 0.8 times to keep the surface tension change and etching rate within a reasonable range, resulting in more uniform etching.

[0081] Based on any of the above embodiments, in a preferred embodiment, in step S03, in the n etchings, a cleaning step is set after each etching is completed; the cleaning step includes sequentially rinsing the etched semi-finished product with deionized water, replacing it with an ethanol solution, replacing it with an isopropanol solution, and drying it with a supercritical inert gas; the cleaning time of each cleaning step is 1 min-10 min, including the endpoint values.

[0082] Wherein, a cleaning step is provided after each etching is completed, and the cleaning step includes sequentially performing deionized water rinsing, ethanol solution replacement, isopropanol solution replacement and drying steps using supercritical inert gas, wherein the surface tension of the ethanol solution and the isopropanol solution is smaller than that of the etching solution, the surface tension of isopropanol is smaller than that of ethanol, a liquid with low surface tension is used for solution replacement to adjust the surface tension, and solutions with stepwise reduced surface tension are used for solution replacement in sequence to avoid different surface tensions in different areas, resulting in local over-etching and affecting the uniformity of etching.

[0083] Specifically, after each etching is completed, the etching solution has poor wettability due to its large surface tension, forming droplets or local residues in the transparent conductive material layer, causing continuous reaction in certain areas and initiating over-etching. Ethanol and isopropanol solutions have low surface tension and stronger liquid fluidity, and can quickly and evenly cover the entire surface of the transparent conductive material layer, as well as microstructures (such as grooves or pores at the micron or nanometer scale), quickly replacing the residual etching solution, reducing local reaction time, and avoiding local over-etching caused by etching solution retention. Moreover, in the microstructure, low surface tension liquids can more easily penetrate into narrow areas through capillary action, remove etching solution residues, and prevent over-etching of hidden areas; therefore, after using ethanol solution for solution replacement, using isopropanol with even lower surface tension for solution replacement can further remove etching solution residues in hidden areas that the ethanol solution failed to remove.

[0084] Preferably, supercritical inert gas is used for drying, including one or more of supercritical CO2, N2, Ar and He.

[0085] Based on any of the above embodiments, in a preferred embodiment, in n etchings, the difference in surface tension of the etching solution between two adjacent etchings is no more than 10 mN / m; in n etchings, the etching rate of each etching is less than or equal to 90 nm / min.

[0086] Based on any of the above embodiments, in a preferred embodiment, the etching angle of the transparent conductive layer 3 is less than or equal to 60°.

[0087] In summary, the etching method for the transparent conductive layer 3 material layer provided in the embodiment of the present application is for sputtering the unalloyed transparent conductive material layer 1. The etching solution surface tension is reduced by stepwise increasing the first solution ratio, thereby controlling the shrinkage of the etching solution. The etching solution temperature is then increased in steps to further reduce the surface tension of the etching solution and control the etching rate. The amount of overetching is controlled by gradually controlling the etching time of each step. The first solution ratio is adjusted, the etching temperature is adjusted, and the etching time is controlled to avoid edge burrs after etching and control the etching angle. Among them, the shrinkage of the etching solution refers to the situation where the solution shrinks into a water droplet shape when the surface tension is high, and the wettability of the transparent conductive material layer is reduced.

[0088] The present application also provides a method for manufacturing an LED chip, which comprises:

[0089] A01: Provide a substrate. The substrate can be a substrate or a conductive substrate. The substrate can be a sapphire substrate, a silicon substrate, a silicon carbide substrate, etc.

[0090] A02: If Figure 5 As shown, Figure 5 The figure is a schematic diagram of the structure for growing an epitaxial stack on a substrate. The epitaxial stack is grown on one surface of the substrate; the epitaxial stack includes a first-type semiconductor layer 5, an active layer 6, and a second-type semiconductor layer 7, stacked sequentially in a direction away from the substrate. One of the first-type semiconductor layer 5 and the second-type semiconductor layer 7 is an N-type semiconductor layer, and the other is a P-type semiconductor layer. In this embodiment, the first-type semiconductor layer 5 is an N-type semiconductor layer, and the material includes, but is not limited to, N-GaN; the second-type semiconductor layer 7 is a P-type semiconductor layer, and the material includes, but is not limited to, P-GaN. The active layer 6 can be a multi-quantum well layer.

[0091] A03: If Figure 6 As shown, Figure 6 This is a schematic diagram of a structure for forming a transparent conductive material layer on an epitaxial stack. Transparent conductive material layer 1 is formed on the surface of the epitaxial stack facing away from the substrate. Transparent conductive material layer 1 can include one or more of ITO, AZO, GZO, FTO, ATO, IZO, IGO, IGZO, IWO, IMO, etc. In the embodiments of this application, ITO is used as an example. Optionally, transparent conductive material layer 1 has a thickness of 900 Å to 5000 Å, inclusive. Transparent conductive material layer 1 can be formed by sputtering.

[0092] A04: If Figure 7 As shown in FIG8 , the transparent conductive material layer 1 is etched using the etching method of any of the above embodiments to form a transparent conductive layer 3. The specific steps are similar to the etching method of the transparent conductive material layer 1 in the above embodiments and will not be repeated here. Figure 7Schematic diagram of the structure of coating photoresist on the transparent conductive material layer. Figure 8 FIG. 3 is a schematic diagram of the structure of the transparent conductive layer 3 formed after etching.

[0093] A05: Fabricate a first electrode 8, which is electrically connected to the first-type semiconductor layer 5. Fabricate a second electrode 9, which is electrically connected to the second-type semiconductor layer 7.

[0094] Based on the above embodiment, in a preferred embodiment, in step A04, as Figure 8 -9, where Figure 9 for Figure 8 A partial enlarged view of A in the middle. After the transparent conductive layer 3 is formed, a suspended structure is formed around the first photoresist layer 2. The transparent conductive layer 3 includes a contact layer 31 and a conductive layer 32 stacked in sequence in a direction away from the substrate; the distance from the edge line on each side of the contact layer 31 to the edge line on the same side of the first photoresist layer 2 is L1, and L1 ≥ 3.5um. The edge lines on each side of the contact layer 31 are the edge lines on each side of the contact layer 31 away from the surface of the substrate. The distance from the edge line on each side of the conductive layer 32 to the edge line on the same side of the first photoresist layer 2 is L2, and L2 ≥ 4um. The edge lines on each side of the conductive layer 32 are the edge lines on each side of the conductive layer 32 close to the surface of the substrate. Among them, in the embodiment of the present application, the contact layer 31 is an ITO contact layer, and the conductive layer 32 is an ITO conductive layer. In this embodiment, the etching angle of the transparent conductive layer is Figure 9 The angle θ is shown.

[0095] Preferably, the conductive layer 32 may be rapidly annealed to form an ohmic contact, wherein the annealing temperature is preferably 400-600° C., inclusive.

[0096] After forming the transparent conductive layer 3 and before forming the first electrode 8 and the second electrode 9, that is, between steps A04 and A05, the following steps are further included:

[0097] A041: If Figure 10 As shown, Figure 10 The first photoresist layer 2 is hardened for the second time to form a second photoresist layer 10 having a second preset pattern; the temperature of the second hardening is 1.1 to 1.5 times the temperature of the first hardening, inclusive.

[0098] A042: Etch the epitaxial stack using the second photoresist layer 10 as a mask to expose part of the surface of the first-type semiconductor layer 5. This step is also known as MESA etching in the art. After MESA etching, a groove exposing the first-type semiconductor layer 5 is formed. After the MESA etching is completed, a debonding step is performed. Optionally, dry etching is used to expose part of the surface of the N-GaN. Preferably, Cl2, Ar, and O2 are used for dry etching, wherein the ratio of Cl2:Ar:O2 is 5:1:2. Preferably, the etching depth is 1-1.4um (including the endpoint value), the sidewall of the groove is a bevel, and the length L3 of the bevel is preferably 1.5-2.0um (including the endpoint value). As Figure 11 As shown, Figure 11 For Figure 10 Schematic diagram of the structure after MESA etching is completed based on the .

[0099] like Figure 11 As shown in FIG12 , in step A05 , the first electrode 8 is disposed on the exposed surface of the first-type semiconductor layer 5 . The second electrode 9 is disposed on the surface of the transparent conductive layer 3 facing away from the substrate.

[0100] Based on any of the above embodiments, in a preferred embodiment, the etching angle of the transparent conductive layer 3 is less than or equal to 60°.

[0101] Based on any of the above embodiments, in a preferred embodiment, after step A05, step A06 is further included: Figure 12 As shown, a passivation material layer is deposited on the side of the LED chip facing away from the substrate. After coating, exposure, development, and hardening, the passivation material layer is etched to expose part of the surface of the first electrode 8 and the second electrode 9 to form a passivation layer 11. Figure 12 For Figure 11 Schematic diagram of the structure after the first electrode, the second electrode and the passivation layer are manufactured on the basis of FIG.

[0102] The method for manufacturing an LED chip provided in the present application adopts any of the above-mentioned etching methods for a transparent conductive material layer 1, and thus has all the beneficial effects of any of the above-mentioned etching methods for a transparent conductive material layer 1. In addition, in the method for manufacturing an LED chip provided in the present application, the first photoresist layer 2 is hardened for a second time to form a second photoresist layer 10 having a second preset pattern, so that MESA etching can be performed using the second photoresist layer 10 as a mask to expose part of the surface of the first-type semiconductor layer 5, and the etching of the transparent conductive material layer and the MESA etching are placed in the same process step, saving the photolithography process steps and simplifying the manufacturing process. After the transparent conductive layer 3 is formed, a suspended structure is formed around the first photoresist layer 2, and the distance from the edge line on each side of the ITO contact layer 31 to the edge line on the same side of the first photoresist layer 2 is set to L1, L1 ≥ 3.5um; the distance from the edge line on each side of the ITO conductive layer 32 to the edge line on the same side of the first photoresist layer 2 is L2, L2 ≥ 4um, to avoid contact between the edge of the transparent conductive layer 3 and the MESA table, resulting in leakage of the LED chip.

[0103] The present application also provides an LED chip, which is manufactured using the method for manufacturing an LED chip described in any of the above embodiments. Therefore, the LED chip has all the beneficial effects of the method for manufacturing an LED chip described in any of the above embodiments.

[0104] It should be understood by those skilled in the art that, in the disclosure of the present invention, the terms "horizontal", "vertical", "upper", "lower", etc. indicating orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the above terms cannot be understood as limiting the present invention.

[0105] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the various embodiments can be referenced to each other.

[0106] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for etching a transparent conductive material layer, characterized in that: include: Providing a transparent conductive material layer to be etched; Applying photoresist, exposing, developing and hardening the surface of the transparent conductive material layer in sequence to obtain a first photoresist layer having a first preset pattern; Using the first photoresist layer as a mask, etching the transparent conductive material layer n times to form a transparent conductive layer, where n is greater than or equal to 2 and n is a positive integer; The etching solution for etching the transparent conductive material layer includes HCl, FeCl3, H2O, and a first solution; From the first etching to the nth etching, the weight percentage of the first solution in the etching solution increases successively, so that the surface tension of the etching solution decreases successively.

2. The method for etching a transparent conductive material layer according to claim 1, wherein: From the first etching to the nth etching, the temperature of the etching solution increases successively.

3. The method for etching a transparent conductive material layer according to claim 2, wherein: From the first etching to the nth etching, the etching time decreases gradually.

4. The method for etching a transparent conductive material layer according to claim 1, wherein: The first solution includes one or more of isopropyl alcohol, methanol, ethylene glycol, propylene glycol methyl ether and acetone.

5. The method for etching a transparent conductive material layer according to claim 1, wherein: In n etchings, a cleaning step is set after each etching is completed; The cleaning step includes sequentially rinsing the etched semi-finished product with deionized water, replacing it with an ethanol solution, replacing it with an isopropanol solution, and drying it with a supercritical inert gas; The cleaning time of each cleaning step is 1 min to 10 min, including the endpoint value.

6. The method for etching a transparent conductive material layer according to claim 5, wherein: The drying using supercritical inert gas includes using one or more of supercritical CO2, N2, Ar and He.

7. The method for etching a transparent conductive material layer according to claim 1, wherein: In n etchings, the weight percentage of the first solution in the i-th etching to the etching solution is W(i), 1<i≤n; wherein 1.1*W(i-1)≤W(i)≤2.5*W(i-1); During the first etching, the weight percentage of the first solution in the etching solution is greater than or equal to 20%.

8. The method for etching a transparent conductive material layer according to claim 2, wherein: In n etchings, the temperature of the etching solution in the i-th etching is T(i), 1<i≤n; Among them, 1.1*T(i-1)≤T(i)≤1.5*T(i-1).

9. The method for etching a transparent conductive material layer according to claim 3, wherein: In n etchings, the etching time of the i-th etching is t(i), 1<i≤n; 0.5*t(i-1)≤t(i)≤0.8*t(i-1).

10. The method for etching a transparent conductive material layer according to claim 1, wherein: In n etchings, the difference in surface tension of the etching solution between two adjacent etchings is no more than 10 mN / m; In the n etchings, the etching rate of each etching is less than or equal to 90 nm / min.

11. A method for manufacturing an LED chip, characterized in that: include: providing a substrate; Growing an epitaxial stack on one side surface of the substrate; the epitaxial stack includes a first-type semiconductor layer, an active layer, and a second-type semiconductor layer stacked in sequence in a direction away from the substrate; forming a transparent conductive material layer on a surface of the epitaxial stack facing away from the substrate; Using the method for etching a transparent conductive material layer according to any one of claims 1 to 10, etching the transparent conductive material layer to form a transparent conductive layer; manufacturing a first electrode, wherein the first electrode is electrically connected to the first-type semiconductor layer; A second electrode is manufactured, wherein the second electrode is electrically connected to the second-type semiconductor layer.

12. The method for manufacturing an LED chip according to claim 11, wherein: After the transparent conductive layer is formed, a suspended structure is formed around the first photoresist layer; The transparent conductive layer includes a contact layer and a conductive layer stacked in sequence in a direction away from the substrate; The distance between the edge line on each side of the contact layer and the edge line on the same side of the first photoresist layer is L1, and L1 is ≥ 3.5 μm; The distance between the edge line on each side of the conductive layer and the edge line on the same side of the first photoresist layer is L2, and L2 is ≥ 4 μm; After forming the transparent conductive layer and before forming the first electrode and the second electrode, the following steps are also included: hardening the first photoresist layer for a second time to form a second photoresist layer having a second preset pattern; The temperature of the second hardening film is 1.1 times to 1.5 times the temperature of the first hardening film, including the endpoint values; etching the epitaxial stack using the second photoresist layer as a mask to expose a portion of the surface of the first-type semiconductor layer; The first electrode is disposed on the exposed surface of the first-type semiconductor layer.

13. An LED chip, characterized in that: The LED chip is manufactured by the method for manufacturing an LED chip according to any one of claims 11 to 12.

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