A device and method for dynamically chemically assisted femtosecond laser etching of silicon carbide wafers

Abstract

The application relates to a device and a method for dynamically-chemically-liquid-assisted femtosecond laser etching of a silicon carbide wafer, which comprises a laser, a working tank, a moving assembly and a liquid storage tank with a water pump installed therein, the focal point of the laser is perpendicular to and directly opposite to the working tank used for placing the silicon carbide wafer, the working tank is a hollow opening structure, the silicon carbide wafer is used to be placed in the working tank and has an optical lens above the silicon carbide wafer; the liquid storage tank has a liquid outlet pipe on one side and a liquid return pipe on the other side, the liquid outlet pipe and the liquid return pipe are both in communication with the working tank above the liquid storage tank, the liquid outlet pipe, the liquid return pipe and the water pump in the liquid storage tank enable the chemical liquid to realize external dynamic circulation and form a water film between the optical lens and the silicon carbide wafer at the same time; the laser is connected with an optical fiber, a laser beam passes through the optical lens and is coupled with the chemical liquid to act on the surface of the silicon carbide wafer to realize laser etching, and the processing rate is ensured while the yield of the silicon carbide wafer is ensured.

Description

Technical Field

[0001] This invention relates to the field of silicon carbide wafer etching technology, and in particular to surface etching and microstructure processing of silicon carbide wafers, specifically a device and method for dynamic chemical liquid-assisted femtosecond laser etching of silicon carbide wafers. Background Technology

[0002] Silicon carbide (SiC) belongs to the third generation of wide-bandgap semiconductors. Compared with first- and second-generation semiconductors, it features a wide bandgap, making it suitable for high-voltage electric field environments and effectively avoiding breakdown problems. It also possesses the following advantages: 1. High hardness, resulting in high wear resistance; 2. High temperature resistance, enabling it to operate normally in harsh high-temperature environments; 3. High stability, as it reacts with oxygen in the air at room temperature to form a silicon oxide film, resisting corrosion under non-harsh conditions. These characteristics allow silicon carbide wafers to significantly reduce the depletion region under the same operating conditions, thereby lowering the resistivity of the drift region, achieving lower on-resistivity and higher power performance. Furthermore, the faster saturated electron drift speed can accelerate transistor switching speed, thus improving the frequency response and overall performance of the circuit, enabling devices to handle higher power and current densities. Semiconductor devices based on single-crystal silicon carbide, such as LED substrates, Schottky diodes (SBD / JBS), and insulated-gate bipolar transistors (IGBTs), can be applied to next-generation PLCs, power supplies, and other fields, accelerating the upgrading and iteration of electronic equipment and promoting the development of industries such as electric vehicles and communications.

[0003] Currently, the main methods for processing silicon carbide wafers include wire sawing, cold separation, electrical discharge machining, and laser drilling. Wire sawing is the mainstream processing technology for silicon carbide. It is a mature technology with a high wafer yield and fast speed, but it can cause mechanical damage. Laser drilling has high processing precision and is a non-contact process that can process complex shapes and fine holes. However, continuous laser or high-pulse-width pulsed laser processing can introduce a heat-affected zone, causing material damage.

[0004] To address the technical problems encountered in the processing of the aforementioned methods, femtosecond lasers have gradually emerged in the market. Femtosecond lasers, with their extremely low processing pulse duration and high peak power, can reduce the thermal impact to some extent. Furthermore, the photochemical interaction of femtosecond lasers with materials avoids thermal impact issues. Their extremely fine processing precision is very suitable for silicon carbide processing, but they produce a large amount of residue buildup at the cut edges.

[0005] Femtosecond laser processing of silicon carbide is generally divided into single-pulse processing and multi-pulse processing. The removal mechanisms mainly include Coulomb explosion and thermal melting. These physical mechanisms enable the material to be removed through non-thermal melting, phase explosion, and vaporization at high energy densities. Simultaneously, femtosecond laser processing typically employs direct-write methods, directly ablating the surface in air. This method generally introduces oxygen and leaves residues and debris at the ablation site. To reduce heat accumulation and defects such as cracks, fragments, and remelted layers caused by the femtosecond laser, a liquid environment and chemical solvent can be introduced into the femtosecond laser processing. Bubbles are induced in the liquid environment, increasing the removal rate through cavitation. The localized high temperature created by the femtosecond laser promotes the reaction between the chemical solvent and the material, accelerating etching. The disadvantages are that the liquid environment dilutes and refracts the laser energy, and the disturbance and aggregation of small bubbles cause energy loss, severely impacting processing efficiency. Current research focuses more on processing in static liquid environments, which cannot avoid the problem of laser refraction caused by air bubbles, leading to irregular ablation of the silicon carbide wafer wall. This affects the yield and utilization rate of silicon carbide wafers, hindering the promotion and application of the above methods in the field of silicon carbide wafer etching technology. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, the first objective of this invention is to provide a device for dynamic chemical liquid-assisted femtosecond laser etching of silicon carbide wafers. This device, by using dynamic chemical liquid, can effectively reduce the surface tension of the liquid, shorten the residence time of bubbles, accelerate bubble explosion, and reduce the obstruction of the laser beam path during the upward movement of bubbles. This avoids the dispersion and loss of laser energy, ensuring the processing rate while maintaining the yield and utilization rate of silicon carbide wafers. This is conducive to the promotion and application of the aforementioned device for dynamic chemical liquid-assisted femtosecond laser etching of silicon carbide wafers in the field of silicon carbide wafer etching technology. The second objective of this invention is to provide a method for etching silicon carbide wafers using a dynamic chemical liquid-assisted femtosecond laser. This method utilizes the aforementioned apparatus for etching silicon carbide wafers using a dynamic chemical liquid. Through the circulating flow of the dynamic chemical liquid, it achieves in-situ, real-time removal of debris and modified layers generated by laser ablation, while significantly reducing the cost of chemical liquid consumables, minimizing ineffective processing time caused by bubble blockage, improving the etching efficiency of silicon carbide wafers, and ensuring the quality of the etched silicon carbide wafers. This facilitates the promotion and application of the aforementioned method for etching silicon carbide wafers using a dynamic chemical liquid-assisted femtosecond laser in the field of silicon carbide wafer etching technology.

[0007] The aforementioned apparatus for dynamic chemical liquid-assisted femtosecond laser etching of silicon carbide wafers and the aforementioned method for dynamic chemical liquid-assisted femtosecond laser etching of silicon carbide wafers are technically related and belong to the same inventive concept.

[0008] To achieve the first objective mentioned above, the present invention employs the following technical solution: a device for dynamic chemical liquid-assisted femtosecond laser etching of silicon carbide wafers, comprising a laser, a working tank, a moving component for driving and adjusting the position of the working tank, and a storage tank with a water pump installed inside. The focal point of the laser is perpendicular to and directly opposite the working tank used to place the silicon carbide wafer. The working tank has a hollow open structure. The silicon carbide wafer is placed in the working tank and has an optical lens located above it. The storage tank has an outlet pipe on one side and a return pipe on the other side. Both the outlet pipe and the return pipe are connected to the working tank located above it. The outlet pipe, the return pipe, and the water pump located in the storage tank enable the chemical liquid to achieve external dynamic circulation while forming a water film between the optical lens and the silicon carbide wafer. The laser is connected to an optical fiber, and the laser beam passes through the optical lens and couples with the chemical liquid to achieve laser etching on the surface of the silicon carbide wafer.

[0009] As a preferred embodiment of the present invention, the liquid storage tank has an inlet flow valve, an outlet flow valve, and a circulation pipeline. The inlet flow valve and the outlet flow valve are respectively connected to the liquid storage tank through the circulation pipeline. The chemical liquid inside the liquid storage tank can be dynamically circulated through the inlet flow valve, the outlet flow valve, the circulation pipeline, and the water pump located in the liquid storage tank.

[0010] As a preferred embodiment of the present invention, a mounting cover for mounting optical lenses is installed at the opening of the working slot, and the mounting cover is sealed to the opening of the working slot.

[0011] As a preferred embodiment of the present invention, a mounting hole is formed at the center of the mounting cover, and the mounting cover is stretched downward from the mounting hole to form a mounting part for mounting an optical lens. A stepped mounting groove is formed in the mounting part, and the optical lens is used to be mounted in the mounting groove.

[0012] As a preferred embodiment of the present invention, a flat worktable is also installed inside the working tank, the silicon carbide wafer is used to place on the worktable, and an adjustment component capable of adjusting the height of the worktable is also installed outside the working tank.

[0013] As a preferred embodiment of the present invention, the optical lens is installed in the mounting groove and the distance between it and the surface of the silicon carbide wafer is 3mm, and the vertical adjustment range of the worktable is 0-3mm.

[0014] In a preferred embodiment of the present invention, the moving component is a three-dimensional motion slide, including an X-axis moving component, a Y-axis moving component and a Z-axis moving component. The X-axis moving component is installed at the bottom of the working groove, the Y-axis moving component is installed on the X-axis moving component, and the Z-axis moving component is connected to the Y-axis moving component.

[0015] As a preferred embodiment of the present invention, the laser is a femtosecond pulse laser with a pulse width of 800 fs, a power adjustment range of 0 to 30 W, and a spot diameter in the micrometer range.

[0016] In a preferred embodiment of the present invention, the inlet and outlet of the working tank are symmetrically arranged along the central axis of the working tank.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: The device for dynamic chemical liquid-assisted femtosecond laser etching of silicon carbide wafers in the present invention has an ingenious structure. It is composed of a laser, a working tank, a moving component for driving and adjusting the position of the working tank, and a storage tank with a water pump installed inside. The storage tank has an outlet pipe on one side and a return pipe on the other side, and both the outlet pipe and the return pipe are connected to the working tank. The outlet pipe, the return pipe, and the water pump located in the storage tank enable the chemical liquid to achieve external dynamic circulation while forming a water film between the optical lens and the silicon carbide wafer. The formation of this water film can effectively reduce the surface tension of the liquid, and the chemical liquid in the working tank is also in a dynamic circulation state, thereby shortening the residence time of bubbles, accelerating bubble explosion, reducing the obstruction of the laser beam path during the upward movement of bubbles, avoiding the dispersion and loss of laser energy, ensuring the processing speed while ensuring the yield and utilization rate of silicon carbide wafers, which is conducive to the promotion and application of the above-mentioned device for dynamic chemical liquid-assisted femtosecond laser etching of silicon carbide wafers in the field of silicon carbide wafer etching technology.

[0018] Furthermore, by sealing the opening of the above-mentioned working tank with an installation cover, the present invention can effectively prevent the chemical liquid in the working tank from splashing outward, thus avoiding chemical liquid loss while ensuring the cleanliness of the etching environment.

[0019] To achieve the second objective mentioned above, the present invention adopts the following technical solution: a method for dynamic chemical liquid-assisted femtosecond laser etching of silicon carbide wafers, comprising the following steps:

[0020] S1. Prepare silicon carbide wafers. Clean the silicon carbide wafers in an ultrasonic environment for about 30 minutes using anhydrous ethanol and acetone solution. Then remove the residual cleaning solution with deionized water and dry the surface of the silicon carbide wafers with nitrogen.

[0021] S2. Prepare a chemical solution by dissolving an appropriate amount of KOH powder in deionized water to obtain a chemical solution with a mass fraction of approximately 3.5 wt%.

[0022] S3. Turn on the water pump to circulate the chemical solution in the storage tank. Then, by adjusting the inlet and outlet flow valves on both sides of the storage tank, the chemical solution inside the storage tank can be dynamically circulated.

[0023] S4. Start the laser, adjust the three-dimensional motion slide so that the laser focus is vertical and directly facing the worktable used to place the silicon carbide wafer, set the processing path and laser parameters, and start processing; the laser parameters include: average power 0.5W~5W, pulse width 800fs, pulse frequency 10KHz~100KHz, and scanning speed 1mm / s~50mm / s.

[0024] S5. After etching is completed, repeat S1 to clean the silicon carbide wafer.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows: The method of dynamic chemical liquid-assisted femtosecond laser etching of silicon carbide wafers in the present invention, by applying the above-mentioned device of dynamic chemical liquid-assisted femtosecond laser etching of silicon carbide wafers, wherein the circulation of chemical liquid in the working tank realizes dynamic chemical liquid, thereby achieving in-situ real-time removal of debris and modified layer generated by laser ablation, while significantly reducing the cost of chemical liquid consumables, reducing the ineffective processing time caused by bubble blockage, improving the etching efficiency of silicon carbide wafers while ensuring the quality of silicon carbide wafer etching products, which is conducive to the promotion and application of the above-mentioned dynamic chemical liquid-assisted femtosecond laser etching of silicon carbide wafers in the field of silicon carbide wafer etching technology. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of a device for dynamic chemical liquid-assisted femtosecond laser etching of silicon carbide wafers in an embodiment of the present invention;

[0027] Figure 2 This is a partial structural schematic diagram of a device for dynamic chemical liquid-assisted femtosecond laser etching of silicon carbide wafers in an embodiment of the present invention;

[0028] Figure 3 This is a schematic diagram of the structure of the mounting cover in an embodiment of the present invention;

[0029] Figure 4 This is a schematic diagram of the bottom structure of the mounting cover in an embodiment of the present invention;

[0030] Figure 5 This is a simulation diagram of the fluid at different times in this invention;

[0031] Figure 6 These are SEM and EDS state diagrams of etching in air;

[0032] Figure 7These are SEM and EDS state diagrams obtained from etching in a chemical solution.

[0033] Reference numerals: 1. Laser; 2. Working tank; 3. Moving assembly; 3-1. X-axis moving assembly; 3-2. Y-axis moving assembly; 3-3. Z-axis moving assembly; 4. Storage tank; 5. Inlet flow valve; 6. Outlet flow valve; 7. Circulation pipeline; 8. Outlet pipe; 9. Return pipe; 10. Silicon carbide wafer; 11. Mounting cover; 11-1. Mounting hole; 11-2. Mounting part; 11-3. Mounting slot; 12. Worktable; 13. Adjustment assembly. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is described below with reference to specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0035] In the description of this invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0036] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0037] Current research focuses more on processing in static liquid environments, which cannot avoid the problem of laser refraction caused by air bubbles, leading to irregular ablation of the silicon carbide wafer wall. This affects the yield and utilization rate of silicon carbide wafers, hindering the promotion and application of the above methods in the field of silicon carbide wafer etching technology.

[0038] like Figures 1 to 7As shown, to solve the above-mentioned technical problems, the present invention provides a device for dynamic chemical liquid-assisted femtosecond laser etching of silicon carbide wafers, mainly composed of a laser 1, a working tank 2, a moving component 3 for driving and adjusting the position of the working tank 2, and a storage tank 4 with a water pump installed inside. The focal point of the laser 1 is perpendicular to and directly opposite the working tank 2 used to place the silicon carbide wafer 10. The working tank 2 has a hollow open structure. The silicon carbide wafer 10 is placed in the working tank 2 and has an optical lens located above it. Specifically, the laser 1 is a femtosecond pulse laser with a pulse width of 800 fs, a power adjustment range of 0-30 W, a spot diameter in the micrometer range, a repetition frequency adjustable from 1 kHz to 1 MHz, a center wavelength of 1030 nm or 1064 nm, and a beam quality factor M² < 1.3 to ensure a high concentration of laser energy in space and time, achieving non-thermal melting removal of silicon carbide material. The aforementioned working trough 2 is a transparent container with an open top, made of quartz glass or acrylic. Inside the trough is a worktable 12 for fixing silicon carbide wafers 10. The height of the worktable 12 is adjustable to accommodate silicon carbide wafers 10 of different thicknesses. Specifically, the worktable 12 is flat, and the silicon carbide wafers 10 are placed on it. An adjustment assembly 13 is also installed outside the working trough 2 to adjust the height of the worktable 12. The adjustment assembly 13 can be a lifting platform structure, specifically including a lifting slider, a lifting rail, a locking element, and a connecting platform connected to the lifting slider. The connecting platform is located at the bottom of the worktable 12, and the height of the worktable 12 is adjusted by moving the lifting slider to drive the connecting platform. The aforementioned working tank 2 has an inlet on one side and an outlet on the other side. The aforementioned storage tank 4 has an outlet pipe 8 on one side, which communicates with the inlet. The aforementioned storage tank 4 has a return pipe 9 on the other side, which communicates with the outlet. Both the outlet pipe 8 and the return pipe 9 are connected to the working tank 2 located above the storage tank 4. The outlet pipe 8, the return pipe 9, and the water pump located inside the storage tank 4 enable the chemical liquid to achieve external dynamic circulation while simultaneously forming a water film between the optical lens and the silicon carbide wafer 10. The aforementioned laser 1 is connected to an optical fiber. The laser beam, through an optical lens, couples with a chemical liquid to the surface of the silicon carbide wafer 10 to achieve laser etching. By using a dynamic chemical liquid, the device can effectively reduce the surface tension of the liquid, shorten the residence time of bubbles in the liquid, accelerate the bubble explosion, and reduce the obstruction of the laser beam path during the upward movement of bubbles. This avoids the dispersion and loss of laser energy, ensuring the processing speed while maintaining the yield and utilization rate of silicon carbide wafers. This is conducive to the promotion and application of the device for dynamic chemical liquid-assisted femtosecond laser etching of silicon carbide wafers in the field of silicon carbide wafer etching technology.

[0039] The aforementioned moving component 3 in this invention is a three-dimensional motion slide, specifically including an X-axis moving component 3-1, a Y-axis moving component 3-2, and a Z-axis moving component 3-3. The X-axis moving component 3-1 is installed at the bottom of the working slot 2, the Y-axis moving component 3-2 is installed on the X-axis moving component 3-1, and the Z-axis moving component 3-3 connects to the Y-axis moving component 3-2. Each of the X-axis moving component 3-1, the Y-axis moving component 3-2, and the Z-axis moving component 3-3 has a slider, a slide rail, and a drive motor. The slider is driven by the drive motor to move on the slide rail to adjust the position of the working slot 2, thereby achieving precise scanning and positioning of the laser focus of the laser 1 relative to the silicon carbide wafer 10.

[0040] The above-mentioned liquid storage tank 4 in this invention has a built-in circulating water pump and a filter device. The liquid storage tank 4 and the working tank 2 are connected by pipelines to form a closed circulation system. The flow rate of the chemical liquid is adjustable within the range of 0.1-5m / s. The bottom of the liquid storage tank 4 is equipped with a constant temperature heating or cooling device to keep the temperature of the chemical liquid in a constant range of 20-60℃.

[0041] In this invention, a mounting cover 11 is installed at the opening of the working tank 2. The mounting cover 11 seals the opening of the working tank 2, and a light-transmitting hole is provided in the center of the mounting cover 11. The optical lens is installed in the light-transmitting hole to ensure the stability of the optical lens, so that the laser beam is focused by the optical lens and perpendicularly incident on the surface of the silicon carbide wafer 10 in the working tank 2. At the same time, it prevents chemical liquid from splashing out, ensuring the cleanliness and stability of the laser beam path. The mounting cover 11 in this invention can form a detachable sealing structure with the opening of the working tank 2 through sealing rings or other sealing components, preventing splashing or overflow of dynamic chemical liquid during circulation, and maintaining a constant liquid level in the working tank 2, ensuring that the laser focus is always at a predetermined depth below the liquid surface, avoiding a decrease in processing quality caused by focus position drift. The sealing structure of the mounting cover 11 can also isolate highly corrosive chemical liquids (such as hydrofluoric acid and potassium hydroxide solution) from the external environment, preventing operators from directly contacting the chemical liquid or inhaling corrosive vapors, improving the safety and environmental friendliness of the device. The aforementioned mounting cover 11 can be made of transparent material (such as quartz glass or acrylic) or an observation window can be opened on the side wall of the mounting cover 11 to facilitate real-time monitoring of the processing area status and achieve quality control of the processing process.

[0042] To further ensure the stability of the optical lens during installation and use, and to enable vertical adjustment of the optical lens, a mounting hole 11-1, i.e., the light-transmitting hole, is formed at the center of the mounting cover 11. The mounting cover 11 is stretched downwards from the mounting hole 11-1 to form a mounting portion 11-2 for mounting the optical lens. The mounting portion 11-2 is cylindrical in shape, and the mounting hole 11-1 in the center is adapted to the shape of the optical lens, and can be circular or square. To further improve the installation speed, a stepped mounting groove 11-3 is formed near the bottom of the mounting portion 11-2, and the optical lens is installed in the mounting groove 11-3. To further ensure the secure installation of the optical lens, a retaining ring can be provided below the optical lens. The retaining ring presses against the edge of the optical lens and is fixedly connected to the bottom of the mounting portion 11-2 by screws or other connectors. After the optical lens is installed, a stable water film can be formed between it and the upper surface of the silicon carbide wafer 10. The aforementioned optical lens can be adjusted vertically within the mounting groove 11-3 to adjust the thickness of the water film and meet different processing conditions. The mounting cover 11 is made of transparent materials such as acrylic, preferably with a wall thickness of 5-15mm. The depth of the mounting hole 11-1 can be designed according to actual operation. The material of the working groove 2 can be the same as that of the mounting cover 11, and the wall thickness can also be the same to ensure that both have the same coefficient of thermal expansion and thermal response rate under laser processing temperature rise or chemical liquid temperature fluctuation environment. This avoids stress concentration or sealing failure at the joint surface of the mounting cover 11 and the working groove 2 due to thermal deformation differences, while ensuring the relative positional accuracy of the optical lens and the bottom surface of the working groove 2 is stable, preventing focus shift caused by thermal drift.

[0043] To prevent chemical liquid from settling inside the storage tank 4, the storage tank 4 in this invention has an inlet flow valve 5, an outlet flow valve 6, and a circulation pipeline 7. The inlet flow valve 5 and the outlet flow valve 6 are connected to the storage tank 4 through the circulation pipeline 7. The chemical liquid inside the storage tank 4 can be dynamically circulated through the inlet flow valve 5, the outlet flow valve 6, the circulation pipeline 7, and the water pump located inside the storage tank 4.

[0044] After the optical lens of this invention is installed in the mounting groove 11-3, the distance between it and the surface of the silicon carbide wafer 10 is 3mm. The 3mm distance ensures that after the laser beam is focused by the optical lens, the focal point is located precisely on the surface of the silicon carbide wafer 10 or at a predetermined depth, achieving a micron-level spot diameter and high energy density. This ensures the non-thermal melting removal effect of the femtosecond laser, and the distance provides sufficient flow channel height for the dynamic chemical liquid circulation, allowing bubbles generated in the processing area to be smoothly discharged laterally with the liquid flow, avoiding the accumulation of bubbles on the lower surface of the optical lens and causing laser scattering. In this embodiment, the vertical adjustment range of the worktable 12 is 0-3mm, which is adapted to the distance between the optical lens and the surface of the silicon carbide wafer 10. When there is a deviation in the thickness of the silicon carbide wafer 10 (usually ±0.1mm) or the laser thermal drift causes the focal point to shift, the worktable 12 can be adjusted up and down within the 0-3mm fine adjustment range to ensure that the laser focal point is always aligned with the surface of the silicon carbide wafer 10. When variable depth etching (such as bevel or stepped structures) is required, the position of the silicon carbide wafer 10 can be adjusted in real time within a 3mm range to achieve dynamic control of the focal depth. In this embodiment, the thickness of the worktable 12 is 20-23mm. A thickness of 20mm or more ensures that the worktable 12 will not bend or deform due to the impact of chemical liquid flow or the reaction force of laser processing when carrying the silicon carbide wafer 10 and the fixture, thereby maintaining the levelness of the surface of the silicon carbide wafer 10 (flatness better than ±0.01mm) and preventing uneven processing depth caused by the tilt of the silicon carbide wafer 10.

[0045] In this embodiment, the inlet and outlet of the working tank 2 are symmetrically arranged along the central axis of the working tank 2. This allows the chemical liquid to enter through the inlet and diffuse evenly to both sides along the central axis, forming a symmetrical laminar flow field. The symmetrical layout can prevent the chemical liquid from forming eddies or stagnant areas in the corners of the tank, ensuring that the chemical liquid in the entire processing area is updated in real time, preventing debris from accumulating locally. In addition, the uniform pressure distribution of the flow field generated by the symmetrical inlet and outlet can effectively reduce the disturbance of turbulent pulsation to the laser beam path, prevent bubbles from accumulating in the turbulent areas of the flow field, and effectively prevent local concentration drops caused by uneven liquid supply (especially in areas where reaction products accumulate), maintaining a stable chemical etching rate and ensuring etching quality.

[0046] This embodiment of a method for dynamic chemical liquid-assisted femtosecond laser etching of silicon carbide wafers includes the following steps:

[0047] S1. Prepare silicon carbide wafer 10. Clean the silicon carbide wafer 10 in an ultrasonic environment with anhydrous ethanol and acetone solution for about 30 minutes. Then remove the residual cleaning solution with deionized water and dry the surface of silicon carbide wafer 10 with nitrogen.

[0048] S2. Prepare a chemical solution by dissolving an appropriate amount of KOH powder in deionized water to obtain a chemical solution with a mass fraction of approximately 3.5 wt%.

[0049] S3. Turn on the water pump to make the chemical solution circulate in the storage tank 4. Then, by adjusting the inlet flow valve 5 and outlet flow valve 6 on both sides of the storage tank 4, the chemical solution inside the storage tank 4 can be dynamically circulated.

[0050] S4. Start laser 1, adjust the three-dimensional motion slide so that the focus of laser 1 is perpendicular and directly facing the worktable 12 used to place silicon carbide wafer 10, set the processing path and laser parameters, and start processing; wherein, the parameters of laser 1 include: average power 0.5W~5W, pulse width 800fs, pulse frequency 10KHz~100KHz, scanning speed 1mm / s~50mm / s;

[0051] S5. After etching is completed, repeat S1 to clean the silicon carbide wafer 10.

[0052] This invention discloses a method for dynamic chemical liquid-assisted femtosecond laser etching of silicon carbide wafers. By employing the aforementioned apparatus for dynamic chemical liquid-assisted femtosecond laser etching of silicon carbide wafers, the circulating flow of the chemical liquid within the working tank achieves dynamic chemical liquid action. This enables in-situ, real-time removal of debris and modified layers generated by laser ablation, while significantly reducing the cost of chemical liquid consumables, minimizing ineffective processing time due to bubble blockage, improving silicon carbide wafer etching efficiency, and ensuring the quality of the etched silicon carbide wafer. This method is beneficial for the promotion and application of the aforementioned dynamic chemical liquid-assisted femtosecond laser etching of silicon carbide wafers in the field of silicon carbide wafer etching technology.

[0053] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those 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 invention; therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0054] Although this document frequently uses the following reference numerals from the figures: 1. Laser; 2. Working tank; 3. Moving assembly; 3-1. X-axis moving assembly; 3-2. Y-axis moving assembly; 3-3. Z-axis moving assembly; 4. Storage tank; 5. Inlet flow valve; 6. Outlet flow valve; 7. Circulation pipeline; 8. Outlet pipe; 9. Return pipe; 10. Silicon carbide wafer; 11. Mounting cover; 11-1. Mounting hole; 11-2. Mounting part; 11-3. Mounting slot; 12. Worktable; 13. Adjustment assembly, etc., the possibility of using other terms is not excluded. These terms are used merely for the convenience of describing and explaining the essence of the invention; interpreting them as any additional limitation would contradict the spirit of the invention.

Claims

1. A device for dynamic chemical liquid-assisted femtosecond laser etching of silicon carbide wafers, characterized in that: The system includes a laser (1), a working tank (2), a moving component (3) for driving and adjusting the position of the working tank (2), and a storage tank (4) with a water pump installed inside. The focal point of the laser (1) is perpendicular to and directly opposite the working tank (2) for placing a silicon carbide wafer (10). The working tank (2) has a hollow open structure. The silicon carbide wafer (10) is placed in the working tank (2) and has an optical lens located above it. The storage tank (4) has a liquid outlet pipe (8) on one side. The other side of the liquid tank (4) has a return pipe (9). The outlet pipe (8) and the return pipe (9) are both connected to the working tank (2) located above the storage tank (4). The outlet pipe (8), the return pipe (9) and the water pump located in the storage tank (4) enable the chemical liquid to achieve external dynamic circulation while forming a water film between the optical lens and the silicon carbide wafer (10). The laser (1) is connected to the optical fiber. The laser beam passes through the optical lens and couples with the chemical liquid to the surface of the silicon carbide wafer (10) to achieve laser etching.

2. The apparatus for dynamic chemical liquid-assisted femtosecond laser etching of silicon carbide wafers according to claim 1, characterized in that: The liquid storage tank (4) has an inlet flow valve (5), an outlet flow valve (6) and a circulation pipeline (7). The inlet flow valve (5) and the outlet flow valve (6) are connected to the liquid storage tank (4) through the circulation pipeline (7). The chemical liquid inside the liquid storage tank (4) can be dynamically circulated through the inlet flow valve (5), the outlet flow valve (6), the circulation pipeline (7) and the water pump located in the liquid storage tank (4).

3. The apparatus for dynamic chemical liquid-assisted femtosecond laser etching of silicon carbide wafers according to claim 1, characterized in that: An mounting cover (11) for mounting optical lenses is installed at the opening of the working slot (2), and the mounting cover (11) is sealed to the opening of the working slot (2).

4. The apparatus for dynamic chemical liquid-assisted femtosecond laser etching of silicon carbide wafers according to claim 3, characterized in that: A mounting hole (11-1) is formed at the center of the mounting cover (11). The mounting cover (11) is stretched downward from the mounting hole (11-1) to form a mounting part (11-2) for mounting optical lenses. A stepped mounting groove (11-3) is formed in the mounting part (11-2) for mounting optical lenses.

5. The apparatus for dynamic chemical liquid-assisted femtosecond laser etching of silicon carbide wafers according to claim 4, characterized in that: The working slot (2) is also equipped with a flat worktable (12), and the silicon carbide wafer (10) is placed on the worktable (12). An adjustment component (13) capable of adjusting the height of the worktable (12) is also installed outside the working slot (2).

6. The apparatus for dynamic chemical liquid-assisted femtosecond laser etching of silicon carbide wafers according to claim 5, characterized in that: After the optical lens is installed in the mounting slot (11-3), the distance between it and the surface of the silicon carbide wafer (10) is 3mm, and the vertical adjustment range of the worktable (12) is 0-3mm.

7. The apparatus for dynamic chemical liquid-assisted femtosecond laser etching of silicon carbide wafers according to claim 1, characterized in that: The moving component (3) is a three-dimensional motion slide, including an X-axis moving component (3-1), a Y-axis moving component (3-2) and a Z-axis moving component (3-3). The X-axis moving component (3-1) is installed at the bottom of the working groove (2), the Y-axis moving component (3-2) is installed on the X-axis moving component (3-1), and the Z-axis moving component (3-3) is connected to the Y-axis moving component (3-2).

8. The apparatus for dynamic chemical liquid-assisted femtosecond laser etching of silicon carbide wafers according to claim 1, characterized in that: The laser (1) is a femtosecond pulse laser with a pulse width of 800fs, a power adjustment range of 0 to 30W, and a spot diameter of micrometers.

9. The apparatus for dynamic chemical liquid-assisted femtosecond laser etching of silicon carbide wafers according to claim 1, characterized in that: The inlet and outlet of the working tank (2) are symmetrically arranged along the central axis of the working tank (2).

10. A method for dynamic chemical liquid-assisted femtosecond laser etching of silicon carbide wafers, comprising an apparatus for dynamic chemical liquid-assisted femtosecond laser etching of silicon carbide wafers as described in any one of claims 1 to 9; characterized in that: Includes the following steps: S1. Prepare silicon carbide wafer (10). Clean the silicon carbide wafer (10) in an ultrasonic environment using anhydrous ethanol and acetone solution for about 30 minutes. Then remove the residual cleaning solution with deionized water and dry the surface of the silicon carbide wafer (10) with nitrogen gas. S2. Prepare a chemical solution by dissolving an appropriate amount of KOH powder in deionized water to obtain a chemical solution with a mass fraction of about 3.5 wt%. S3. Turn on the water pump to circulate the chemical solution in the storage tank (4). Then, adjust the inlet flow valve (5) and outlet flow valve (6) on both sides of the storage tank (4) to make the storage solution flow. The chemical liquid inside the liquid tank (4) is dynamically circulated; S4, start the laser (1), adjust the three-dimensional motion slide so that the focus of the laser (1) is vertical and directly facing the worktable (12) used to place the silicon carbide wafer (10), set the processing path and laser parameters, and start processing; among them, the parameters of the laser (1) include: average power 0.5W~5W, pulse width 800fs, pulse frequency 10KHz~100KHz, scanning speed 1mm / s~50mm / s; S5, after etching is completed, repeat S1 to clean the silicon carbide wafer (10).

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