Batch wet etching apparatus for aluminum nitride substrates and method thereof

Abstract

The application provides a batch wet etching device for aluminum nitride substrates and a method for etching and cleaning substrates using the device. The device includes a substrate loading system, a heating system, and an etching and cleaning system, which respectively realize batch substrate loading, automatic heating, batch etching and cleaning, and solution recycling functions. The substrate loading system uses a multi-hole tray to load multiple substrates simultaneously, achieving batch etching. The heating system can heat the substrates to a certain temperature before etching, avoiding excessive stress on the substrates due to a large temperature difference between the molten alkali solution and the substrates at the beginning of etching, which can cause the substrates to crack. The etching and cleaning system is designed for recycling, ensuring waste liquid recycling and reuse. The application designs a batch and automated wet etching device for aluminum nitride substrates, improving etching efficiency and effectiveness, increasing quality inspection yield, and being suitable for industrial batch substrate defect etching and defect detection.

Description

Technical Field

[0001] This invention relates to the field of semiconductor material preparation technology, specifically to a batch wet etching apparatus and method for aluminum nitride substrates. Background Technology

[0002] Aluminum nitride, as an ultrawide bandgap semiconductor material, has advantages such as high bandgap (6.2 eV), high thermal conductivity (340% (m·K)), high breakdown field strength, good ultraviolet transmittance, and chemical and thermal stability. It is an ideal material for ultraviolet optoelectronic devices and can be widely used in deep ultraviolet LEDs, ultraviolet curing, ultraviolet detectors and other fields. It has broad application prospects and is currently a research focus in the field of semiconductor materials.

[0003] The primary defect type within aluminum nitride crystals is dislocation. The main method for assessing the defect level involves selective chemical etching (SCIE) to create regular pits from dislocations, and then determining the dislocation density by statistically analyzing the pit density. This method is simple and effective, and is commonly used to detect defect types and densities in substrates such as aluminum nitride, silicon carbide, and gallium nitride. However, SCIE is currently generally performed on single substrates, resulting in low efficiency. Furthermore, this etching method can be irreversible and destructive for large substrates; especially when the substrate size exceeds 2 inches, it is highly susceptible to breakage during etching. This is because molten KOH and NaOH reach temperatures of 400-600°C. Rapidly immersing a room-temperature substrate in the high-temperature etching solution or experiencing sudden temperature fluctuations during removal generates significant internal stress, leading to substrate breakage. Additionally, uneven heating during etching, especially on large substrates, increases the likelihood of cracking, resulting in etching failure or inaccurate defect analysis, ultimately causing the loss of expensive substrates. Currently, aluminum nitride substrate production yields are low, substrate value is high, and corrosion-induced fragmentation leads to a sharp increase in defect detection costs, severely hindering the research and commercialization of large-size, high-quality aluminum nitride substrates. Therefore, there is an urgent need to develop an etching device and method to solve these problems. Summary of the Invention

[0004] Based on the above-mentioned problems in the prior art, the present invention provides a batch wet etching apparatus for aluminum nitride substrates and its usage method, which realizes batch etching and uniform etching effect of aluminum nitride substrates, solves the problem of corrosion cracking of large-size substrates, and improves the safety, environmental protection and high efficiency of substrate etching.

[0005] To achieve the above-mentioned objectives, the present invention adopts the following technical solution.

[0006] First, the present invention provides a batch wet etching apparatus for aluminum nitride substrates. The apparatus includes a substrate loading system, a substrate heating system, and an etching and cleaning system, which respectively realize functions such as batch substrate loading, automated heating, batch etching of substrates, cleaning, and solution recovery.

[0007] The substrate loading system includes a multi-hole tray, a tray cover, and a handle. The multi-hole tray has several holes, and the tray cover is stacked on top of each other to hold the aluminum nitride substrate in each hole. The tray cover also has through holes at positions corresponding to the multi-hole tray.

[0008] Furthermore, the porous tray has several stepped through holes for supporting the aluminum nitride substrate; the tray cover is sized to match the porous tray and has through holes at positions corresponding to the stepped through holes of the tray; fixing holes are provided at the edges of the porous tray and at corresponding positions of the tray cover to secure them; positioning holes are provided at the center of the porous tray and at corresponding positions of the tray cover for the handle to pass through; the end of the handle has a protrusion for positioning the entire loading system on the heating system.

[0009] Furthermore, the stepped through-hole consists of a small hole at the bottom and a large hole at the top, forming a step at the connection point for placing the aluminum nitride substrate. The diameter of the small hole is slightly smaller than the diameter of the aluminum nitride substrate, and the diameter of the large hole is slightly larger than the diameter of the aluminum nitride substrate. The diameter of the through-hole on the tray cover is slightly smaller than the diameter of the aluminum nitride substrate. When loading the substrate, the aluminum nitride substrate is placed on the step of the stepped through-hole, the tray cover is placed on top, and the two are secured using the corresponding fixing holes on the edges of the tray and tray cover to ensure that the wafer does not wobble during etching. Then, the assembled tray and tray cover are inserted into the handle through the central positioning hole to complete the assembly of the aluminum nitride substrate.

[0010] The etching and cleaning system includes an open container, a container lid, and various etching and cleaning solution supply and circulation devices, each connected to the container via pipes. Each etching and cleaning solution supply and circulation device consists of a solution tank, valves controlling the entry and exit of the etching and cleaning solutions, a recovery tank, and connecting pipes. For the etching and cleaning of the aluminum nitride substrate of this invention, the etching and cleaning solutions used include alkaline solutions, concentrated hydrochloric acid, dilute hydrochloric acid, and EDI water. Therefore, each etching and cleaning solution supply and circulation device includes: a molten alkaline solution tank, an alkaline solution recovery tank, an alkaline solution inlet valve, an alkaline solution outlet valve, a concentrated hydrochloric acid solution tank, a concentrated hydrochloric acid recovery tank, a concentrated hydrochloric acid inlet valve, a concentrated hydrochloric acid outlet valve, a dilute hydrochloric acid solution tank, a dilute hydrochloric acid recovery tank, a dilute hydrochloric acid inlet valve, a dilute hydrochloric acid outlet valve, an EDI water tank, an EDI water recovery tank, an EDI water inlet valve, an EDI water outlet valve, and corresponding connecting pipes. During the etching and cleaning of aluminum nitride substrates, each etching solution or cleaning solution is added to its respective solution tank, and its flow into the container is controlled by the inlet valve. Then, its flow out of the container to each recovery tank is controlled by the outlet valve. Each recovery tank is connected to its respective solution tank, forming a cycle of etching and cleaning solutions.

[0011] Furthermore, a heater is provided at the bottom of the molten alkali solution tank to heat the molten alkali inside the tank, which can heat the molten alkali solution to the temperature required for substrate etching.

[0012] The substrate heating system includes a heating platform, a heat-conducting plate, and a thermocouple. The heating platform is placed under the bottom wall of the container, the heat-conducting plate is placed at the bottom of the container, and the temperature-sensing end of the thermocouple extends into the container to measure the temperature near the center of the tray. A groove is centrally located on the upper surface of the heat-conducting plate. During operation, the substrate loading system, with the assembled aluminum nitride substrate, is inserted into the groove of the heat-conducting plate via a protrusion at the end of its handle, ensuring the entire tray is perfectly centered and the bottom of the tray is in contact with the heat-conducting plate. Heat from the heating platform is transferred to the substrate on the tray through the heat-conducting plate.

[0013] More specifically, the diameter of the aluminum nitride substrate can be 1-200 mm.

[0014] Preferably, the molten alkaline solution can be one or a mixture of NaOH and KOH.

[0015] Preferably, the materials of the multi-hole tray, tray cover, handle, container, heat-conducting block, and container cover are selected from one or more of alkali-resistant corrosion-resistant materials such as tungsten, nickel, tantalum, and rhenium.

[0016] The present invention also provides a batch wet etching method for aluminum nitride substrates. When using the above-mentioned batch wet etching apparatus for aluminum nitride of the present invention, the method includes the following specific steps.

[0017] S1: Place multiple aluminum nitride substrates into the porous tray, cover the tray with the lid, and secure the tray and lid by fixing the edges with the fixing holes; the handle passes through the positioning hole in the center of the tray and the lid, and the protrusion at the bottom of the handle engages in the groove of the heat-conducting block to ensure that the entire tray is completely centered, and then cover the container with the lid; the container lid blocks the exchange of substances between the container and the outside, providing a relatively stable environment for the corrosion process.

[0018] S2: Insert the thermocouple to a position above the center of the tray inside the container, turn on the heating platform, and heat the aluminum nitride substrate to temperature T1; simultaneously, turn on the heater at the bottom of the molten alkali solution tank to heat the molten alkali inside to temperature T2; then open the alkali solution inlet valve to allow the molten alkali solution heated to T2 to flow into the container. When the alkali solution completely submerges the thermocouple, close the alkali solution inlet valve. At this point, maintain the thermocouple temperature at T3 using the heating platform and hold it at that temperature for time t1. Subsequently, open the alkali solution outlet valve to drain all the alkali solution in the container into the alkali solution recovery tank, and then close the alkali solution outlet valve.

[0019] S3: The temperature of the aluminum nitride substrate is slowly reduced to room temperature via a heating platform at a cooling rate V1. The concentrated hydrochloric acid inlet valve is opened, allowing concentrated hydrochloric acid to flow from the concentrated hydrochloric acid solution tank into the container, completely immersing the aluminum nitride substrate. After standing for time t2, the concentrated hydrochloric acid outlet valve is opened, and the concentrated hydrochloric acid is recycled to the concentrated hydrochloric acid recovery tank. The dilute hydrochloric acid inlet valve is opened, allowing dilute hydrochloric acid to flow from the dilute hydrochloric acid solution tank into the container, completely immersing the aluminum nitride substrate. After standing for time t3, the dilute hydrochloric acid outlet valve is opened, and the dilute hydrochloric acid solution is recycled to the dilute hydrochloric acid recovery tank. First, the EDI water inlet valve is opened, allowing EDI water to flow into the container. Once the EDI water completely immerses the aluminum nitride substrate, the EDI water outlet valve is opened, and the EDI water flows back to the EDI water recovery tank, forming a flowing EDI water stream. This is maintained for time t4. Then, the EDI water inlet valve is closed first, and after all the EDI water in container 5 has flowed out, the EDI water outlet valve is closed.

[0020] S4: Open the container lid, remove the entire substrate loading system using the handle, and unload the etched and cleaned aluminum nitride substrate from the tray.

[0021] Preferably, in step S2, the thermocouple is inserted within 5 mm of the center of the tray cover;

[0022] Preferably, the pH value of the molten alkaline solution in step S2 is greater than 12;

[0023] Preferably, in step S2, T1 is 300-600℃, T2 is 300-600℃, and the temperature difference between T1 and T2 is within ±10℃.

[0024] Preferably, the heat preservation time t1 in step S2 is 0.5-30 min;

[0025] Preferably, the cooling rate V1 in step S3 is 0.1-2℃ / min;

[0026] Preferably, in step S3, time t2 is 0.5-2 min, time t3 is 0.5-30 min, and time t4 is 0.5-10 min.

[0027] The present invention achieves the following beneficial effects:

[0028] 1) The etching apparatus of this invention enables batch loading of aluminum nitride substrates, achieving automated heating, etching, and...

[0029] It features cleaning and recycling functions. With a high degree of automation, excellent efficiency and corrosion effect, this device also provides safe and environmentally friendly substrate corrosion, making it highly suitable for industrial production.

[0030] 2) The corrosion device and method of the present invention provide a stable thermal environment for the aluminum nitride substrate and its surroundings, solve the problem of corrosion cracking of large-size substrates, reduce the economic losses caused by corrosion cracking, thereby improving the corrosion effect and enhancing the quality inspection level of defects. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of a batch wet etching apparatus for aluminum nitride substrates according to the present invention.

[0032] Wherein: 1 is a multi-hole tray, 2 is an aluminum nitride substrate, 3 is a tray cover, 4 is a handle, 5 is a container, 6 is a heat-conducting block, 7 is a heating platform, 8 is a container cover, 9 is a thermocouple, 10-1 is a molten alkali solution tank, 10-2 is an alkali solution recovery tank, 10-a is an alkali solution inlet valve, 10-b is an alkali solution outlet valve, 11-1 is a concentrated hydrochloric acid solution tank, 11-2 is a concentrated hydrochloric acid recovery tank, 11-a is a concentrated hydrochloric acid inlet valve, 11-b is a concentrated hydrochloric acid outlet valve, 12-1 is a dilute hydrochloric acid solution tank, 12-2 is a dilute hydrochloric acid recovery tank, 12-a is a dilute hydrochloric acid inlet valve, 12-b is a dilute hydrochloric acid outlet valve, 13-1 is an EDI water tank, 13-2 is an EDI water recovery tank, 13-a is an EDI water inlet valve, and 13-b is an EDI water outlet valve. Detailed Implementation

[0033] The present invention will now be described in detail with reference to the specific embodiments shown in the accompanying drawings. However, these embodiments do not limit the present invention, and any structural, methodological, or functional modifications made by those skilled in the art based on these embodiments are included within the scope of protection of the present invention.

[0034] A schematic diagram of a batch wet etching apparatus for aluminum nitride substrates used in various embodiments of the present invention is shown below. Figure 1 As shown. The aluminum nitride substrate to be etched and cleaned is fixed by a porous tray 1 and a tray cover 3, and the substrate is heated before etching by a heat-conducting block 6 and a heating platform 7. The container cover 8 blocks the interaction of substances inside and outside the container, providing a relatively stable environment for etching. The coordinated operation of the valves 10-a (alkaline solution inlet valve), 10-b (alkaline solution outlet valve), 11-a (concentrated hydrochloric acid inlet valve), 11-b (concentrated hydrochloric acid outlet valve), 12-a (dilute hydrochloric acid inlet valve), 12-b (dilute hydrochloric acid outlet valve), 12-a (EDI water inlet valve), and 12-b (EDI water outlet valve) enables directional flow of the solution.

[0035] Example 1

[0036] In this embodiment, 20 stepped through-holes, matching a 2-inch aluminum nitride substrate, are evenly distributed in the multi-hole tray. Each stepped through-hole consists of a lower hole with a diameter slightly less than 2 inches and an upper hole with a diameter slightly greater than 2 inches, connected together. The aluminum nitride substrate rests on the step formed at the connection point. The through-hole diameter on the tray cover is the same as the small hole in the stepped through-hole on the tray.

[0037] In addition, in this embodiment, the materials of the multi-hole tray, tray cover, handle, container, heat-conducting block, and container cover are made of alkali-resistant nickel.

[0038] Combination Figure 1 The specific steps for batch corrosion cleaning are as follows.

[0039] S1: Place 20 2-inch aluminum nitride substrates 2 into the nickel porous tray 1, cover with the nickel tray cover 3, and secure them using the corresponding fixing holes on the edges of the tray and tray cover to ensure that the aluminum nitride substrates do not move during the etching process. Then, insert the assembled tray and tray cover through the central positioning hole into the nickel handle 4 to complete the assembly of the aluminum nitride substrates. Then, insert the lower protrusion of the nickel handle 4 into the groove of the nickel heat-conducting block 6 to ensure that the entire tray is completely centered, and cover with the nickel container cover 8.

[0040] S2: Insert the rhenium thermocouple 9 to a position 3 mm from the center of the tray cover 3. Turn on the heating platform 7 and heat the substrate 6 to 300°C. Open the inlet valve 10-a of the KOH and NaOH mixed solution, allowing the molten KOH and NaOH mixed solution 10-1 (heated to 305°C, pH=14) to flow into the container 5. When the KOH and NaOH mixed solution 10-1 completely submerges the rhenium thermocouple, close the inlet valve 10-a and maintain the temperature of the thermocouple 9 at 302°C using the heating platform 7 for 30 minutes. Then, open the outlet valve 10-b of the KOH and NaOH mixed solution to drain all the KOH and NaOH mixed solution in the container into the alkali solution recovery tank 10-2, and close the outlet valve 10-b.

[0041] S3: Slowly lower the temperature of the aluminum nitride substrate 2 to room temperature using the heating platform 7 at a cooling rate of 2℃ / min, then remove the thermocouple 9. Open the concentrated hydrochloric acid inlet valve 11-a, allowing concentrated hydrochloric acid to flow from the concentrated hydrochloric acid solution tank 11-1 into the container 5, completely immersing the entire aluminum nitride substrate 2. Let it stand for 1 minute, then open the concentrated hydrochloric acid outlet valve 11-b, recovering the concentrated hydrochloric acid into the concentrated hydrochloric acid recovery tank 11-2. Open the dilute hydrochloric acid inlet valve 12-a, allowing dilute hydrochloric acid to flow from the dilute hydrochloric acid solution tank 12-1 into the container 5, completely immersing the entire aluminum nitride substrate 2. Let it stand for 10 minutes, then open the dilute hydrochloric acid outlet valve 12-b, recovering the dilute hydrochloric acid solution into the dilute hydrochloric acid recovery tank 12-2. First, open the EDI water inlet valve 13-a, allowing EDI water to flow into container 5. Once the EDI water completely submerges the entire aluminum nitride substrate 2, open the EDI water outlet valve 13-b to return the water to the EDI water recovery tank 13-2, creating a flowing EDI water stream. Maintain this flow for 1 minute. Then, close the EDI water inlet valve 13-a first, and after all the EDI water in container 5 has flowed out, close the EDI water outlet valve 13-b.

[0042] S4: Open the container lid 8, remove the entire substrate loading system using the handle 4, and remove the etched and cleaned aluminum nitride substrate 2 from the tray.

[0043] Example 2

[0044] In this embodiment, the porous tray has 15 stepped through-holes, 5 of which are matched with a 4-inch aluminum nitride substrate and the other 10 are matched with a 2-inch aluminum nitride substrate. The through-holes on the tray cover correspond one-to-one with the stepped through-holes on the porous tray.

[0045] In addition, in this embodiment, the materials of the multi-hole tray, tray cover, handle, container, heat-conducting block, and container cover are tungsten, which is resistant to alkali corrosion.

[0046] S1: Place 5 φ100mm and 10 2inch aluminum nitride substrates 2 into the tungsten porous tray 1, cover with the tungsten tray cover 3, place the entire tungsten tray 1 into the tungsten handle 4, and let the protrusion at the bottom of the tungsten handle 4 fit into the groove of the tungsten heat-conducting block 6 to ensure that the entire tray is completely centered, and cover with the tungsten container cover 8.

[0047] S2: Insert the tungsten thermocouple 9 to a position 2 mm from the center of the tray cover 3. Turn on the heating platform 7 and heat the substrate 6 to 600°C. Open the KOH solution inlet valve 10-a and let the molten KOH solution 10-1, heated to 592°C and with a pH of 12.5, flow into the container 5. When the KOH and solution 10-1 completely submerge the tungsten thermocouple, close the KOH solution inlet valve 10-a and maintain the temperature of the thermocouple 9 at 596°C using the heating platform 7 for 3 minutes. Then open the KOH solution outlet valve 10-b to drain all the KOH solution in the container into the alkali solution recovery tank 10-2, and close the alkali solution outlet valve 10-b.

[0048] S3: Slowly lower the temperature of the aluminum nitride substrate 2 to room temperature using the heating platform 7 at a cooling rate of 0.1℃ / min, then remove the thermocouple 9. Open the concentrated hydrochloric acid inlet valve 11-a, allowing concentrated hydrochloric acid to flow from the concentrated hydrochloric acid solution tank 11-1 into the container 5, completely immersing the entire aluminum nitride substrate 2. Let it stand for 0.5 minutes, then open the concentrated hydrochloric acid outlet valve 11-b, recovering the concentrated hydrochloric acid into the concentrated hydrochloric acid recovery tank 11-2. Open the dilute hydrochloric acid inlet valve 12-a, allowing dilute hydrochloric acid to flow from the dilute hydrochloric acid solution tank 12-1 into the container 5, completely immersing the entire aluminum nitride substrate 2. Let it stand for 5 minutes, then open the dilute hydrochloric acid outlet valve 12-b, recovering the dilute hydrochloric acid solution into the dilute hydrochloric acid recovery tank 12-2. First, open the EDI water inlet valve 13-a, allowing EDI water to flow into container 5. Once the EDI water completely submerges the entire aluminum nitride substrate 2, open the EDI water outlet valve 13-b to return the water to the EDI water recovery tank 13-2, creating a flowing EDI water stream. Maintain this flow for 5 minutes. Then, first close the EDI water inlet valve 13-a, and after all the EDI water in container 5 has flowed out, close the EDI water outlet valve 13-b.

[0049] S4: Open the container lid 8, remove the tray using the handle 4, and remove the etched and cleaned aluminum nitride substrate 2 from the tray.

[0050] Example 3

[0051] In this embodiment, the multi-position tray has 30 stepped through-holes, 20 of which are matched with a 1-inch aluminum nitride substrate and the other 10 are matched with a 2-inch aluminum nitride substrate. The through-holes on the tray cover correspond one-to-one with the stepped through-holes on the multi-position tray.

[0052] In addition, in this embodiment, the materials of the multi-hole tray, tray cover, handle, container, heat-conducting block, and container cover are made of alkali-resistant nickel.

[0053] S1: Place 20 1-inch and 10 2-inch aluminum nitride substrates 2 into the nickel porous tray 1, cover with the nickel tray cover 3, place the entire tantalum tray 1 into the nickel handle 4, and insert the protrusion at the bottom of the nickel handle 4 into the groove of the nickel heat-conducting block 6 to ensure that the entire tray is completely centered, and cover with the nickel container cover 8.

[0054] S2: Insert the rhenium thermocouple 9 to a position 1 mm from the center of the tray cover 3. Turn on the heating platform 7 and heat the substrate 6 to 400°C. Open the inlet valve 10-a of the KOH and NaOH mixed solution, and let the NaOH solution 10-1, heated to 406°C and with a pH of 12, flow into the container 5. When the NaOH solution 10-1 completely submerges the rhenium thermocouple, close the NaOH solution inlet valve 10-a. Maintain the temperature of the thermocouple 9 at 406°C through the heating platform 7 and keep it at this temperature for 12 minutes. Then open the NaOH mixed solution outlet valve 10-b to drain all the NaOH mixed solution in the container into the alkali solution recovery tank 10-2, and close the alkali solution outlet valve 10-b.

[0055] S3: Slowly lower the temperature of the aluminum nitride substrate 2 to room temperature using the heating platform 7 at a cooling rate of 1.5℃ / min, then remove the thermocouple 9. Open the concentrated hydrochloric acid inlet valve 11-a, allowing concentrated hydrochloric acid to flow from the concentrated hydrochloric acid solution tank 11-1 into the container 5, completely immersing the entire aluminum nitride substrate 2. Let it stand for 1.5 minutes, then open the concentrated hydrochloric acid outlet valve 11-b, recovering the concentrated hydrochloric acid into the concentrated hydrochloric acid recovery tank 11-2. Open the dilute hydrochloric acid inlet valve 12-a, allowing dilute hydrochloric acid to flow from the dilute hydrochloric acid solution tank 12-1 into the container 5, completely immersing the entire aluminum nitride substrate 2. Let it stand for 25 minutes, then open the dilute hydrochloric acid outlet valve 12-b, recovering the dilute hydrochloric acid solution into the dilute hydrochloric acid recovery tank 12-2. First, open the EDI water inlet valve 13-a, allowing EDI water to flow into container 5. Once the EDI water completely submerges the entire aluminum nitride substrate 2, open the EDI water outlet valve 13-b to return the water to the EDI water recovery tank 13-2, creating a flowing EDI water stream. Maintain this flow for 5 minutes. Then, first close the EDI water inlet valve 13-a, and after all the EDI water in container 5 has flowed out, close the EDI water outlet valve 13-b.

[0056] S4: Open the container lid 8, remove the tray using the handle 4, and remove the etched and cleaned aluminum nitride substrate 2 from the tray.

[0057] Example 4

[0058] The aluminum nitride substrate loading system used in this embodiment is the same as that in Embodiment 3. The porous tray, tray cover, handle, container, heat-conducting block, and container lid are made of alkali-resistant tantalum.

[0059] S1: Place 20 1-inch and 10 2-inch aluminum nitride substrates 2 into the tantalum porous tray 1, cover with the tantalum tray cover 3, place the entire tantalum tray 1 into the nickel handle 4, the lower part of the tantalum handle 4 has a protrusion that can be inserted into the groove of the tantalum heat-conducting block 6 to ensure that the entire tray is completely centered, and cover with the tantalum container cover 8.

[0060] S2: Insert the rhenium thermocouple 9 to a position 1 mm from the center of the tray cover 3. Turn on the heating platform 7 and heat the substrate 6 to 510°C. Open the inlet valve 10-a of the KOH and NaOH mixed solution, allowing the KOH and NaOH mixed solution 10-1 (heated to 512°C, pH=13) to flow into the container 5. When the NaOH solution 10-1 completely submerges the rhenium thermocouple, close the KOH and NaOH mixed solution inlet valve 10-a. Maintain the temperature of the thermocouple 9 at 512°C using the heating platform 7 and hold for 8 minutes. Then, open the KOH and NaOH mixed solution outlet valve 10-b to drain all the KOH and NaOH mixed solution in the container into the alkali solution recovery tank 10-2, and close the alkali solution outlet valve 10-b.

[0061] S3: Slowly lower the temperature of the aluminum nitride substrate 2 to room temperature using the heating platform 7 at a cooling rate of 1℃ / min, then remove the thermocouple 9. Open the concentrated hydrochloric acid inlet valve 11-a, allowing concentrated hydrochloric acid to flow from the concentrated hydrochloric acid solution tank 11-1 into the container 5, completely immersing the entire aluminum nitride substrate 2. Let it stand for 0.5 min, then open the concentrated hydrochloric acid outlet valve 11-b, recovering the concentrated hydrochloric acid into the concentrated hydrochloric acid recovery tank 11-2. Open the dilute hydrochloric acid inlet valve 12-a, allowing dilute hydrochloric acid to flow from the dilute hydrochloric acid solution tank 12-1 into the container 5, completely immersing the entire aluminum nitride substrate 2. Let it stand for 20 min, then open the dilute hydrochloric acid outlet valve 12-b, recovering the dilute hydrochloric acid solution into the dilute hydrochloric acid recovery tank 12-2. First, open the EDI water inlet valve 13-a, allowing EDI water to flow into container 5. Once the EDI water has completely submerged the aluminum nitride substrate 2, open the EDI water outlet valve 13-b to return the water to the EDI water recovery tank 13-2, creating a flowing EDI water stream. Maintain this flow for 8 minutes. Then, first close the EDI water inlet valve 13-a, and after all the EDI water in container 5 has flowed out, close the EDI water outlet valve 13-b.

[0062] S4: Open the container lid 8, remove the tray using the handle 4, and remove the etched and cleaned aluminum nitride substrate 2 from the tray.

[0063] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A batch wet etching apparatus for aluminum nitride substrates, characterized in that: The device includes a substrate loading system, a substrate heating system, and an etching and cleaning system, which respectively realize the functions of batch substrate loading, automated heating, batch substrate etching, cleaning, and solution recovery. The substrate loading system includes a porous tray, a tray cover, and a handle. The porous tray has several holes, and the tray cover and the tray cover are stacked one on top of each other to hold the aluminum nitride substrate in the holes. The tray cover also has through holes at positions corresponding to the positions on the porous tray. Positioning holes for the handle to pass through are provided at the center of the porous tray and at corresponding positions on the tray cover. The end of the handle has a protrusion for positioning the entire loading system on the heating system. The etching and cleaning system includes an open container, a container lid, and various etching and cleaning solution supply and circulation devices. Each etching and cleaning solution supply and circulation device is connected to the container via pipelines. Each etching and cleaning solution supply and circulation device consists of a solution tank, valves for controlling the entry and exit of the etching and cleaning solutions, a recovery tank, and connecting pipelines. The etching and cleaning solutions are stored in their respective solution tanks, flow into the container through valves, and after completing substrate etching or cleaning in the container, they enter the respective recovery tanks through valves and then flow back to the respective solution tanks, completing the recycling process. The substrate heating system includes a heating platform, a heat-conducting plate, and a thermocouple. The heating platform is placed under the bottom wall of the container, the heat-conducting plate is placed at the bottom of the container, and the temperature-sensing end of the thermocouple extends into the container to measure the temperature at a specific point inside the container. The heat-conducting plate has a groove at the center of its upper surface. During operation, the substrate loading system with the assembled aluminum nitride substrate is inserted into the groove of the heat-conducting plate through the protrusion at the end of its handle, ensuring that the entire tray is completely centered and that the bottom of the tray is in contact with the heat-conducting plate. The heat from the heating platform is transferred to the substrate on the tray through the heat-conducting plate.

2. The batch wet etching apparatus for aluminum nitride substrates according to claim 1, characterized in that: The multi-hole tray has several holes that are stepped through holes. Each stepped through hole consists of a small hole at the bottom and a large hole at the top connected together, forming a step at the connection point, for placing an aluminum nitride substrate. The diameter of the small hole is slightly smaller than the diameter of the aluminum nitride substrate, and the diameter of the large hole is slightly larger than the diameter of the aluminum nitride substrate. The diameter of the through hole on the tray cover is slightly smaller than the diameter of the aluminum nitride substrate.

3. The batch wet etching apparatus for aluminum nitride substrates according to claim 1, characterized in that: The multi-perforated tray and the corresponding position of the tray cover are provided with fixing holes to fix the multi-perforated tray and the tray cover. When loading the substrate, the upper and lower corresponding fixing holes on the edges of the tray and the tray cover are used to fix the two to ensure that the substrate does not shake during the etching process. Then, the assembled tray and the tray cover are inserted into the handle through the central positioning hole to complete the assembly of the aluminum nitride substrate.

4. The batch wet etching apparatus for aluminum nitride substrates according to claim 1, characterized in that: The etching and cleaning solutions used in the wet etching process include alkaline solutions, concentrated hydrochloric acid, dilute hydrochloric acid, and EDI water. The supply and circulation devices for each etching and cleaning solution include: a molten alkaline solution tank, an alkaline solution recovery tank, an alkaline solution inlet valve, an alkaline solution outlet valve, a concentrated hydrochloric acid solution tank, a concentrated hydrochloric acid recovery tank, a concentrated hydrochloric acid inlet valve, a concentrated hydrochloric acid outlet valve, a dilute hydrochloric acid solution tank, a dilute hydrochloric acid recovery tank, a dilute hydrochloric acid inlet valve, a dilute hydrochloric acid outlet valve, an EDI water tank, an EDI water recovery tank, an EDI water inlet valve, an EDI water outlet valve, and corresponding connecting pipes. During the etching and cleaning of the aluminum nitride substrate, each etching or cleaning solution is added to its respective solution tank, its inlet valve controls its flow into the container, and its outlet valve controls its flow out of the container to the respective recovery tank. Each recovery tank is connected to its respective solution tank, forming a cycle of etching and cleaning solutions.

5. The batch wet etching apparatus for aluminum nitride substrates according to claim 4, characterized in that: A heater is installed at the bottom of the molten alkali solution tank to heat the molten alkali in the tank to the substrate etching temperature.

6. The batch wet etching apparatus for aluminum nitride substrates according to claim 4, characterized in that: The molten alkaline solution is one or a mixture of two of NaOH and KOH.

7. The batch wet etching apparatus for aluminum nitride substrates according to claim 1, characterized in that: The aluminum nitride substrate has a diameter of 1-200 mm.

8. The batch wet etching apparatus for aluminum nitride substrates according to claim 1, characterized in that: The materials of the multi-hole tray, tray cover, handle, container, heat-conducting block, and container cover are selected from one or more of the alkali-resistant corrosion-resistant materials such as tungsten, nickel, tantalum, and rhenium.

9. A batch wet etching method for aluminum nitride substrates, characterized in that, The batch wet etching process employs the aluminum nitride substrate batch wet etching apparatus according to any one of claims 1-8, and includes the following steps: S1, Place the aluminum nitride substrate into the porous tray, cover the tray with the lid, and fix the tray and the lid with the fixing holes on the edge; The handle passes through the positioning hole in the center of the tray and the lid, and the protrusion at the bottom of the handle is inserted into the groove of the heat-conducting block to ensure that the entire tray is completely centered, and then cover the container with the lid. S2, insert the thermocouple into the container near the center of the tray cover, turn on the heating platform, and heat the aluminum nitride substrate to temperature T1; simultaneously, turn on the heater at the bottom of the molten alkali solution tank to heat the molten alkali in the tank to temperature T2; then open the alkali solution inlet valve to let the molten alkali solution heated to T2 flow into the container. When the alkali solution completely submerges the thermocouple, close the alkali solution inlet valve. At this time, maintain the temperature of the thermocouple at T3 using the heating platform and hold it at that temperature for time t1; then open the alkali solution outlet valve to discharge all the alkali solution in the container into the alkali solution recovery tank, and close the alkali solution outlet valve. S3, the temperature of the aluminum nitride substrate is slowly reduced to room temperature by a heating platform at a cooling rate V1; the concentrated hydrochloric acid inlet valve is opened, and concentrated hydrochloric acid flows from the concentrated hydrochloric acid solution tank into the container, completely immersing the aluminum nitride substrate. After standing for time t2, the concentrated hydrochloric acid outlet valve is opened, and the concentrated hydrochloric acid is recycled to the concentrated hydrochloric acid recovery tank; the dilute hydrochloric acid inlet valve is opened, and dilute hydrochloric acid flows from the dilute hydrochloric acid solution tank into the container, completely immersing the aluminum nitride substrate. After standing for time t3, the dilute hydrochloric acid outlet valve is opened, and the dilute hydrochloric acid solution is recycled to the dilute hydrochloric acid recovery tank; first, the EDI water inlet valve is opened, and EDI water flows into the container. After the EDI water completely immerses the aluminum nitride substrate, the EDI water outlet valve is opened, and the EDI water flows back to the EDI water recovery tank, forming a flowing EDI water flow. This is maintained for time t4. Then, the EDI water inlet valve is closed first, and after the EDI water in the container has completely flowed out, the EDI water outlet valve is closed; S4. Open the container lid, remove the entire substrate loading system using the handle, and unload the etched and cleaned aluminum nitride substrate from the tray.

10. A batch wet etching method for aluminum nitride substrates according to claim 9, characterized in that: In step S2, the thermocouple is inserted within 5 mm of the center of the tray cover.

11. The batch wet etching method for aluminum nitride substrates according to claim 9, characterized in that: In step S2, the pH value of the molten alkaline solution is greater than 12.

12. The method for batch wet etching of aluminum nitride substrates according to claim 9, characterized in that: In step S2, T1 is 300-600℃, T2 is 300-600℃, and the temperature difference between T1 and T2 is within ±10℃.

13. The batch wet etching method for aluminum nitride substrates according to claim 9, characterized in that... The heat preservation time t1 in step S2 is 0.5-30 min.

14. The batch wet etching method for aluminum nitride substrates according to claim 9, characterized in that: In step S3, the cooling rate V1 is 0.1-2℃ / min.

15. A batch wet etching method for aluminum nitride substrates according to claim 9, characterized in that: In step S3, time t2 is 0.5-2 min, time t3 is 0.5-30 min, and time t4 is 0.5-10 min.

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