Batch wet etching device and method for aluminum nitride substrate

Abstract

The invention provides a batch wet etching device for aluminum nitride substrates and a method for etching and cleaning the substrates in batches by using the device. The device comprises a substrate loading system, a heating system and a corrosion cleaning system which are respectively used for realizing the functions of batch substrate loading, automatic heating, batch corrosion cleaning and solution recovery. A multi-hole-site tray is adopted in the substrate loading system, so that a plurality of substrates can be loaded at the same time, and batch corrosion is realized. The heating system can heat the substrate, so that the substrate reaches a certain temperature before corrosion treatment is started, and cracking of the substrate due to overlarge stress caused by large temperature difference between a molten alkali solution and the substrate in the initial corrosion stage is avoided. The corrosion cleaning system is designed in a recycling mode, and waste liquid recycling treatment and recycling are guaranteed. According to the design and process method of the batch and automatic wet etching device for the aluminum nitride substrate, the etching efficiency and effect are improved, the quality inspection yield is improved, and the method is suitable for defect etching and defect detection of industrial batch substrates.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor material preparation, and in particular to a batch wet etching device for aluminum nitride substrates and a use method thereof. Background Art

[0002] As an ultra-wide bandgap semiconductor material, aluminum nitride has the advantages of high bandgap width (6.2ev), high thermal conductivity (340% (m·K)), high breakdown field strength, good ultraviolet transmittance, chemical and thermal stability, etc. It is an ideal ultraviolet optoelectronic device material and can be widely used in deep ultraviolet LEDs, ultraviolet curing, ultraviolet detectors and other fields. It has broad application prospects and is the current research focus in the field of semiconductor materials.

[0003] The main defect type inside aluminum nitride crystals is dislocation defects. The main method for evaluating its defect level is to use selective chemical etching to etch dislocations into regular corrosion pits and determine the dislocation density by counting the density of the corrosion pits. This evaluation method is simple and effective, and is a common method for detecting defect types and densities in substrates such as aluminum nitride, silicon carbide, and gallium nitride. However, the selective chemical etching method currently generally performs single-piece etching, which is inefficient. In addition, this etching method is very likely to be an irreversible destructive detection method for large-sized substrates; especially when the size is greater than 2 inches, the substrate is very likely to break during the etching process. This is because the temperature of molten KOH and NaOH is as high as 400-600℃, and the room temperature substrate quickly enters the high-temperature etching solution or the temperature rises and falls during the removal of the substrate, resulting in large internal stress, which causes the substrate to break, and the substrate is too large and unevenly heated during the etching process, resulting in an increased probability of cracking, which leads to corrosion failure or inability to accurately analyze defects, resulting in the loss of expensive substrates. At present, the production yield of aluminum nitride substrates is low, the substrate value is high, and corrosion and cracking will cause a sharp increase in defect detection costs, which seriously hinders the research and marketization of large-scale high-quality aluminum nitride substrates. Therefore, it is urgent to develop an etching device and method to solve the above problems. Summary of the invention

[0004] Based on the above problems in the prior art, the present invention provides a batch wet etching device for aluminum nitride substrates and a method of using the same, which can achieve batch etching of aluminum nitride substrates and uniform etching effects, while solving the corrosion cracking problem of large-size substrates and improving the safety, environmental protection and high efficiency of substrate etching.

[0005] To achieve the above-mentioned object of the invention, the present invention adopts the following technical scheme.

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

[0007] Among them, the substrate loading system includes a multi-porous tray, a tray cover, and a handle. The multi-porous tray is distributed with a plurality of holes, and the tray cover is stacked up and down to clamp the aluminum nitride substrate in each hole. The tray cover is also provided with through holes corresponding to the upper and lower positions of the multi-porous tray.

[0008] Furthermore, the several holes distributed on the porous tray are several stepped through holes for placing the aluminum nitride substrate; the tray cover has a size matching that of the porous tray and is provided with through holes at positions corresponding to the stepped through holes of the tray; fixing holes for fixing the two are provided at the edge of the porous tray and at positions corresponding to the tray cover; a positioning hole for the handle to pass through is provided at the center of the porous tray and at a position corresponding to the tray cover; a protrusion is provided at the end of the handle for positioning the entire loading system on the heating system.

[0009] Furthermore, the stepped through hole is composed of a small hole at the bottom and a large hole at the top, and a step is formed at the connection point, which is used to place the aluminum nitride substrate. The aperture of the small hole is slightly smaller than the diameter of the aluminum nitride substrate, and the aperture of the large hole is slightly larger than the diameter of the aluminum nitride substrate. The aperture 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, and the tray cover is covered. The tray and the tray cover are fixed by the upper and lower corresponding fixing holes set on the edges to ensure that the wafer does not shake during the etching process. 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 corrosion cleaning system includes an upper opening container, a container cover matched with the container, and each corrosion liquid and cleaning liquid supply circulation device, and each corrosion liquid and cleaning liquid supply circulation device is connected to the container through pipelines. Each corrosion liquid and cleaning liquid supply circulation device is respectively composed of a solution tank, a valve for controlling the corrosion liquid and cleaning liquid to enter and exit the container, a recovery tank and a connecting pipeline; for the corrosion cleaning of the aluminum nitride substrate of the present invention, the corrosion liquid and cleaning liquid used are alkaline solution, concentrated hydrochloric acid, dilute hydrochloric acid and EDI water, so each corrosion liquid and cleaning liquid supply 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 pipelines. When etching and cleaning the aluminum nitride substrate, each etching liquid or cleaning liquid is added to its own solution tank, controlled to flow into the container by an inlet valve, and then controlled to flow out of the container to each recovery tank by an outlet valve. Each recovery tank is connected to each solution tank, respectively, to form a recycling system for etching liquid and cleaning liquid.

[0011] Furthermore, a heater is provided at the bottom of the molten alkali solution tank for heating the molten alkali in the solution tank, and the molten alkali solution can be heated to a temperature required for substrate corrosion.

[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 measuring end of the thermocouple extends into the container to measure the temperature of a point near the center of the tray. A groove is provided at the center of the upper surface of the heat conducting plate. When working, the substrate loading system with the aluminum nitride substrate assembled is inserted into the groove of the heat conducting plate through the protrusion at the end of its handle to ensure that the entire tray is completely centered and the bottom of the tray is in contact with the heat conducting plate. The heat of 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 may be 1-200 mm.

[0014] Preferably, the molten alkali solution may be NaOH, KOH or a mixture of the two.

[0015] Preferably, the material of the porous tray, tray cover, handle, container, heat conductive block and container cover is selected from one or more of tungsten, nickel, tantalum, rhenium and the like among alkali corrosion resistant materials.

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

[0017] S1: Place multiple aluminum nitride substrates into a porous tray, cover the tray cover, and fix the tray to the tray cover through the fixed holes on the edge; the handle passes through the positioning hole in the center of the tray and the tray cover, and the protrusion at the bottom of the handle is inserted into the groove of the heat conductive block to ensure that the entire tray is completely centered, and then cover the container cover; the container cover 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 the position above the center of the tray in the container, turn on the heating platform, and heat the aluminum nitride substrate to T1 temperature; at the same time, turn on the heater at the bottom of the molten alkali solution box to heat the molten alkali in the box to T2 temperature; then open the alkali solution inlet valve, and let the molten alkali solution heated to T2 flow into the container. When the alkali solution completely immerses the thermocouple, close the alkali solution inlet valve. At this time, the temperature of the thermocouple is maintained at T3 by the heating platform, and kept warm for t1 time. Then open the alkali solution outlet valve, discharge all the alkali solution in the container into the alkali solution recovery box, and close the alkali solution outlet valve.

[0019] S3: Slowly lower the temperature of the aluminum nitride substrate to room temperature at a cooling rate of V1 through the heating platform; open the concentrated hydrochloric acid inlet valve, and the concentrated hydrochloric acid flows from the concentrated hydrochloric acid solution tank into the container to completely immerse the aluminum nitride substrate, stand for t2 time, open the concentrated hydrochloric acid outlet valve, and the concentrated hydrochloric acid is recovered into the concentrated hydrochloric acid recovery tank. Open the dilute hydrochloric acid inlet valve, and the dilute hydrochloric acid flows from the dilute hydrochloric acid solution tank into the container to completely immerse the aluminum nitride substrate, stand for t3 time, open the dilute hydrochloric acid outlet valve, and the dilute hydrochloric acid solution is recovered into the dilute hydrochloric acid recovery tank. First open the EDI water inlet valve, and the EDI water flows into the container. When the EDI water height completely immerses the aluminum nitride substrate, open the EDI water outlet valve, and the EDI water flows back to the EDI water recovery tank to form a circulating EDI water flow, and maintain t4 time, then close the EDI water inlet valve first, and after the EDI water in the container 5 has completely flowed out, close the EDI water outlet valve.

[0020] S4: Open the container cover, take out the entire substrate loading system through the handle, and unload the etched and cleaned aluminum nitride substrate on the tray.

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

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

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

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

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

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

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

[0028] 1) The etching device of the present invention realizes batch loading of aluminum nitride substrates and realizes automated heating, etching,

[0029] Cleaning and recycling functions. It has a high degree of automation, good use efficiency and corrosion effect. At the same time, the device provides substrate corrosion safety and environmental protection, and is very suitable for industrial production.

[0030] 2) The corrosion device of the present invention is combined with the use method to 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The present invention is a schematic structural diagram of a batch wet etching device for aluminum nitride substrates.

[0032] Wherein: 1 is a porous tray, 2 is an aluminum nitride substrate, 3 is a tray cover, 4 is a handle, 5 is a container, 6 is a heat conductive 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 DESCRIPTION

[0033] The present invention will be described in detail below in conjunction with the specific embodiments shown in the accompanying drawings. However, these embodiments do not limit the present invention, and any structural, methodological, or functional changes made by a person skilled in the art based on these embodiments are all within the scope of protection of the present invention.

[0034] A schematic diagram of the structure of a batch wet etching device for aluminum nitride substrates used in various embodiments of the present invention is shown in FIG. 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 by a heat conductive block 6 and a heating platform 7 before etching. The container cover 8 blocks the interaction of substances inside and outside the container, providing a relatively stable environment for corrosion. The coordination of the alkaline solution inlet valve 10-a, the alkaline solution outlet valve 10-b, the concentrated hydrochloric acid inlet valve 11-a, the concentrated hydrochloric acid outlet valve 11-b, the dilute hydrochloric acid inlet valve 12-a, the dilute hydrochloric acid outlet valve 12-b, the EDI water inlet valve 12-a and the EDI water outlet valve 12-b valves can realize the directional flow of the solution.

[0035] Embodiment 1

[0036] In this embodiment, 20 stepped through holes matching the 2-inch aluminum nitride substrate are evenly distributed in the multi-hole tray. The stepped through hole is composed of a small hole with a lower aperture slightly smaller than 2 inches and a large hole with an upper aperture slightly larger than 2 inches. The aluminum nitride substrate is placed on the step formed at the connection. The through hole on the tray cover has the same aperture as the small hole in the stepped through hole on the tray.

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

[0038] Combination Figure 1 , the specific batch corrosion cleaning steps are as follows.

[0039] S1: Place 20 2-inch aluminum nitride substrates 2 into the nickel porous tray 1, cover it with the nickel tray cover 3, and fix the tray and tray cover through the corresponding upper and lower fixing holes set on the edges to ensure that the aluminum nitride substrate does not shake during the etching process. Then insert the assembled tray and tray cover into the nickel handle 4 through the central positioning hole to complete the assembly of the aluminum nitride substrate. Then insert the protrusion at the bottom of the nickel handle 4 into the groove of the nickel heat conductive block 6 to ensure that the entire tray is completely centered, and cover it 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. Open 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, and let the molten KOH and NaOH mixed solution 10-1, which has been heated to 305°C and has a pH of 14, flow into the container 5. When the KOH and NaOH mixed solution 10-1 completely immerses the rhenium thermocouple, close the inlet valve 10-a of the KOH and NaOH mixed solution, and maintain the temperature of the thermocouple 9 at 302°C through the heating platform 7, and keep it warm for 30 minutes. Then open the outlet valve 10-b of the KOH and NaOH mixed solution, discharge all the KOH and NaOH mixed solutions in the container into the alkaline solution recovery tank 10-2, and close the alkaline solution outlet valve 10-b.

[0041] S3: Slowly lower the temperature of the aluminum nitride substrate 2 to room temperature at a cooling rate of 2°C / min through the heating platform 7, and withdraw the thermocouple 9. Open the concentrated hydrochloric acid inlet valve 11-a, and the concentrated hydrochloric acid flows from the concentrated hydrochloric acid solution tank 11-1 into the container 5, completely immersing all the aluminum nitride substrates 2, let it stand for 1 minute, open the concentrated hydrochloric acid outlet valve 11-b, and the concentrated hydrochloric acid is recovered into the concentrated hydrochloric acid recovery tank 11-2. Open the dilute hydrochloric acid inlet valve 12-a, and the dilute hydrochloric acid flows from the dilute hydrochloric acid solution tank 12-1 into the container 5, completely immersing all the aluminum nitride substrates 2, let it stand for 10 minutes, open the dilute hydrochloric acid outlet valve 12-b, and the dilute hydrochloric acid solution is recovered into the dilute hydrochloric acid recovery tank 12-2. First open the EDI water inlet valve 13-a, and allow the EDI water to flow into the container 5. When the EDI water level completely submerges the entire aluminum nitride substrate 2, open the EDI water outlet valve 13-b to allow the water to flow back into the EDI water recovery tank 13-2, forming a circulating EDI water flow, which is maintained for 1 minute. Then close the EDI water inlet valve 13-a, and when the EDI water in the container 5 has completely flowed out, close the EDI water outlet valve 13-b.

[0042] S4: Open the container cover 8, take out the entire substrate loading system through the handle 4, and remove the aluminum nitride substrate 2 that has been etched and cleaned from the tray.

[0043] Embodiment 2

[0044] In this embodiment, 15 stepped through holes are arranged in the multi-hole tray, 5 of which match the 4-inch aluminum nitride substrate and the other 10 match the 2-inch aluminum nitride substrate. The through holes on the tray cover correspond to and match the stepped through holes on the multi-hole tray.

[0045] In addition, in this embodiment, the porous tray, tray cover, handle, container, heat conductive block, and container cover are made of tungsten which is resistant to alkali corrosion.

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

[0047] S2: Insert the tungsten thermocouple 9 to a distance of 2 mm from the center of the tray cover 3. Open 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, which has been heated to 592°C and has a pH of 12.5, flow into the container 5. When the KOH and solution 10-1 completely immerse the tungsten thermocouple, close the KOH solution inlet valve 10-a, and maintain the temperature of the thermocouple 9 at 596°C through the heating platform 7, and keep it warm for 3 minutes. Then open the KOH solution outlet valve 10-b, discharge all the KOH solution in the container into the alkaline solution recovery tank 10-2, and close the alkaline solution outlet valve 10-b.

[0048] S3: Slowly lower the temperature of the aluminum nitride substrate 2 to room temperature at a cooling rate of 0.1°C / min through the heating platform 7, and withdraw the thermocouple 9. Open the concentrated hydrochloric acid inlet valve 11-a, and the concentrated hydrochloric acid flows from the concentrated hydrochloric acid solution tank 11-1 into the container 5, completely immersing all the aluminum nitride substrates 2, let it stand for 0.5 minutes, open the concentrated hydrochloric acid outlet valve 11-b, and the concentrated hydrochloric acid is recovered into the concentrated hydrochloric acid recovery tank 11-2. Open the dilute hydrochloric acid inlet valve 12-a, and the dilute hydrochloric acid flows from the dilute hydrochloric acid solution tank 12-1 into the container 5, completely immersing all the aluminum nitride substrates 2, let it stand for 5 minutes, open the dilute hydrochloric acid outlet valve 12-b, and the dilute hydrochloric acid solution is recovered into the dilute hydrochloric acid recovery tank 12-2. First open the EDI water inlet valve 13-a, and allow the EDI water to flow into the container 5. When the EDI water level completely submerges the entire aluminum nitride substrate 2, open the EDI water outlet valve 13-b to allow the water to flow back into the EDI water recovery tank 13-2, forming a circulating EDI water flow, which is maintained for 5 minutes. Then close the EDI water inlet valve 13-a, and when the EDI water in the container 5 has completely flowed out, close the EDI water outlet valve 13-b.

[0049] S4: Open the container cover 8, take out the tray through the handle 4, and remove the etched and cleaned aluminum nitride substrate 2 on the tray.

[0050] Embodiment 3

[0051] The multi-hole tray used in this embodiment is provided with 30 stepped through holes, 20 of which match the 1-inch aluminum nitride substrate and the other 10 match the 2-inch aluminum nitride substrate. The through holes on the tray cover correspond to and match the stepped through holes on the multi-hole tray one by one.

[0052] In addition, in this embodiment, the porous tray, tray cover, handle, container, heat conductive 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 it with the nickel tray cover 3, place the entire tantalum tray 1 into the nickel handle 4, insert the protrusion at the bottom of the nickel handle 4 into the groove of the nickel heat conductive block 6 to ensure that the entire tray is completely centered, and cover it with the nickel container cover 8.

[0054] S2: Insert the rhenium thermocouple 9 to a distance of 1 mm from the center of the tray cover 3. Open 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, which has been heated to 406°C and has a PH of 12, flow into the container 5. When the NaOH solution 10-1 completely immerses the rhenium thermocouple, close the inlet valve 10-a of the NaOH solution, maintain the temperature of the thermocouple 9 at 406°C through the heating platform 7, and keep it warm for 12 minutes. Then open the outlet valve 10-b of the NaOH mixed solution, discharge all the NaOH mixed solution in the container into the alkaline solution recovery tank 10-2, and close the alkaline solution outlet valve 10-b.

[0055] S3: Slowly lower the temperature of the aluminum nitride substrate 2 to room temperature at a cooling rate of 1.5°C / min through the heating platform 7, and withdraw the thermocouple 9. Open the concentrated hydrochloric acid inlet valve 11-a, and the concentrated hydrochloric acid flows from the concentrated hydrochloric acid solution tank 11-1 into the container 5, completely immersing all the aluminum nitride substrates 2, let it stand for 1.5 minutes, open the concentrated hydrochloric acid outlet valve 11-b, and the concentrated hydrochloric acid is recovered into the concentrated hydrochloric acid recovery tank 11-2. Open the dilute hydrochloric acid inlet valve 12-a, and the dilute hydrochloric acid flows from the dilute hydrochloric acid solution tank 12-1 into the container 5, completely immersing all the aluminum nitride substrates 2, let it stand for 25 minutes, open the dilute hydrochloric acid outlet valve 12-b, and the dilute hydrochloric acid solution is recovered into the dilute hydrochloric acid recovery tank 12-2. First open the EDI water inlet valve 13-a, and allow the EDI water to flow into the container 5. When the EDI water level completely submerges the entire aluminum nitride substrate 2, open the EDI water outlet valve 13-b to allow the water to flow back into the EDI water recovery tank 13-2, forming a circulating EDI water flow, which is maintained for 5 minutes. Then close the EDI water inlet valve 13-a, and when the EDI water in the container 5 has completely flowed out, close the EDI water outlet valve 13-b.

[0056] S4: Open the container cover 8, take out the tray through the handle 4, and remove the etched and cleaned aluminum nitride substrate 2 on the tray.

[0057] Embodiment 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 cover are made of tantalum which is resistant to alkali corrosion.

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

[0060] S2: Insert the rhenium thermocouple 9 to 1mm from the center of the tray cover 3. Turn on the heating platform 7 and heat the substrate 6 to 510℃. Open the inlet valve 10-a of the KOH and NaOH mixed solution, and let the KOH and NaOH mixed solution 10-1, which has been heated to 512℃ and has a PH of 13, flow into the container 5. When the NaOH solution 10-1 completely immerses the rhenium thermocouple, close the inlet valve 10-a of the KOH and NaOH mixed solution, maintain the temperature of the thermocouple 9 at 512℃ through the heating platform 7, and keep it warm for 8 minutes. Then open the outlet valve 10-b of the KOH and NaOH mixed solution, discharge all the KOH and NaOH mixed solutions in the container into the alkaline solution recovery box 10-2, and close the alkaline solution outlet valve 10-b.

[0061] S3: Slowly lower the temperature of the aluminum nitride substrate 2 to room temperature at a cooling rate of 1°C / min through the heating platform 7, and withdraw the thermocouple 9. Open the concentrated hydrochloric acid inlet valve 11-a, and the concentrated hydrochloric acid flows from the concentrated hydrochloric acid solution tank 11-1 into the container 5, completely immersing all the aluminum nitride substrates 2, let it stand for 0.5 minutes, open the concentrated hydrochloric acid outlet valve 11-b, and the concentrated hydrochloric acid is recovered into the concentrated hydrochloric acid recovery tank 11-2. Open the dilute hydrochloric acid inlet valve 12-a, and the dilute hydrochloric acid flows from the dilute hydrochloric acid solution tank 12-1 into the container 5, completely immersing all the aluminum nitride substrates 2, let it stand for 20 minutes, open the dilute hydrochloric acid outlet valve 12-b, and the dilute hydrochloric acid solution is recovered into the dilute hydrochloric acid recovery tank 12-2. First open the EDI water inlet valve 13-a, and allow the EDI water to flow into the container 5. When the EDI water is completely submerged in the aluminum nitride substrate 2, open the EDI water outlet valve 13-b to allow the water to flow back into the EDI water recovery tank 13-2, forming a circulating EDI water flow, which is maintained for 8 minutes. Then close the EDI water inlet valve 13-a, and when the EDI water in the container 5 is completely out, close the EDI water outlet valve 13-b.

[0062] S4: Open the container cover 8, take out the tray through the handle 4, and remove the etched and cleaned aluminum nitride substrate 2 on the tray.

[0063] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A batch wet etching device 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, automatic heating, batch substrate etching, cleaning and solution recovery; The substrate loading system includes a multi-hole tray, a tray cover, and a handle. The multi-hole tray is provided with a plurality of holes, and the tray cover is stacked up and down to clamp the aluminum nitride substrate in each hole. The tray cover is also provided with through holes corresponding to the upper and lower positions of the multi-hole tray. A positioning hole for the handle to pass through is provided at the center of the multi-hole tray and at the corresponding position of the tray cover. A protrusion is provided at the end of the handle for positioning the entire loading system on the heating system. The etching and cleaning system comprises an upper opening container, a container cover matched with the container, and each etching liquid and cleaning liquid supply circulation device, and each etching liquid and cleaning liquid supply circulation device is connected to the container through pipelines; each etching liquid and cleaning liquid supply circulation device is respectively composed of a solution tank, a valve for controlling the etching liquid and cleaning liquid to enter and exit the container, a recovery tank and a connecting pipeline; the etching liquid and cleaning liquid are respectively stored in each solution tank, flow into the container through valve control, and after the substrate is etched or cleaned in the container, they enter each recovery tank through valves, and then flow back to each solution tank again to complete the recycling; The substrate heating system comprises 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 measuring end of the thermocouple extends into the container to measure the temperature of a specific point in the container; Among them, a groove is provided in the center of the upper surface of the heat conducting plate; when working, the substrate loading system equipped with the aluminum nitride substrate is inserted into the groove of the heat conducting plate through the protrusion at the end of its handle to ensure that the entire tray is completely centered and the bottom of the tray is in contact with the heat conducting plate. The heat of the heating platform is transferred to the substrate on the tray through the heat conducting plate.

2. The batch wet etching device for aluminum nitride substrate according to claim 1, characterized in that: The plurality of holes distributed on the porous tray are a plurality of stepped through holes, which are composed of a small hole at the bottom and a large hole at the top, and a step is formed at the connection point, and are used to place the aluminum nitride substrate; the aperture of the small hole is slightly smaller than the diameter of the aluminum nitride substrate, and the aperture of the large hole is slightly larger than the diameter of the aluminum nitride substrate; the aperture of the through hole on the tray cover is slightly smaller than the diameter of the aluminum nitride substrate.

3. The batch wet etching device for aluminum nitride substrate according to claim 1, characterized in that: The edges of the porous tray and the corresponding positions of the tray cover are provided with fixing holes for fixing the porous tray and the tray cover; when loading the substrate, the tray and the tray cover are fixed by the upper and lower corresponding fixing holes provided on the edges to ensure that the substrate does not shake during the etching process; 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.

4. The batch wet etching device for aluminum nitride substrate according to claim 1, characterized in that: The etching liquid and cleaning liquid used in the wet etching include alkaline solution, concentrated hydrochloric acid, dilute hydrochloric acid and EDI water; the etching liquid and cleaning liquid supply circulation device 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; when etching and cleaning the aluminum nitride substrate, each etching liquid or cleaning liquid is added to its own solution tank, controlled to flow into the container through its own inlet valve, and then controlled to flow out of the container to each recovery tank through its own outlet valve, and each recovery tank is respectively connected to each solution tank to form a recycling use of the etching liquid and the cleaning liquid.

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

6. The batch wet etching device for aluminum nitride substrate according to claim 4, characterized in that: The molten alkali solution is NaOH, KOH or a mixture of the two.

7. The batch wet etching device for aluminum nitride substrate according to claim 1, characterized in that: The diameter of the aluminum nitride substrate is 1-200 mm.

8. The batch wet etching device for aluminum nitride substrate according to claim 1, characterized in that: The material of the porous tray, tray cover, handle, container, heat conductive block and container cover is selected from one or more of tungsten, nickel, tantalum, rhenium and the like among the alkali corrosion resistant materials.

9. A batch wet etching method for aluminum nitride substrates, characterized in that: The batch wet etching adopts the aluminum nitride substrate batch wet etching device according to any one of claims 1 to 8, comprising the following steps: S1, placing the aluminum nitride substrate into a porous tray, covering the tray cover, and fixing the tray to the tray cover through the fixing holes on the edge; the handle passes through the positioning holes in the center of the tray and the tray cover, and the protrusion at the bottom of the handle is inserted into the groove of the heat conductive block to ensure that the entire tray is completely centered, and then the container cover is covered; S2, insert the thermocouple into the container close to the center of the tray cover, turn on the heating platform, and heat the aluminum nitride substrate to T1 temperature; at the same time, turn on the heater at the bottom of the molten alkali solution box to heat the molten alkali in the box to T2 temperature; then open the alkali solution inlet valve, and let the molten alkali solution heated to T2 flow into the container. When the alkali solution completely immerses the thermocouple, close the alkali solution inlet valve, and at this time, maintain the temperature of the thermocouple at T3 unchanged through the heating platform, and keep it warm for t1 time; then open the alkali solution outlet valve, discharge all the alkali solution in the container into the alkali solution recovery box, and close the alkali solution outlet valve; S3, slowly lower the temperature of the aluminum nitride substrate to room temperature at a cooling rate of V1 through the heating platform; open the concentrated hydrochloric acid inlet valve, and the concentrated hydrochloric acid flows from the concentrated hydrochloric acid solution tank into the container to completely immerse the aluminum nitride substrate, let it stand for t2 time, open the concentrated hydrochloric acid outlet valve, and the concentrated hydrochloric acid is recovered into the concentrated hydrochloric acid recovery tank. Open the dilute hydrochloric acid inlet valve, and the dilute hydrochloric acid flows from the dilute hydrochloric acid solution tank into the container to completely immerse the aluminum nitride substrate, let it stand for t3 time, open the dilute hydrochloric acid outlet valve, and the dilute hydrochloric acid solution is recovered into the dilute hydrochloric acid recovery tank; first open the EDI water inlet valve, and the EDI water flows into the container, and when the EDI water height completely immerses the aluminum nitride substrate, open the EDI water outlet valve, and the EDI water flows back to the EDI water recovery tank to form a circulating EDI water flow, and maintain for t4 time, then close the EDI water inlet valve first, and after the EDI water in the container 5 has completely flowed out, close the EDI water outlet valve; S4, open the container cover, take out the entire substrate loading system through the handle, and unload the aluminum nitride substrate that has been etched and cleaned on the tray.

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

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

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

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

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

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