Dry etching method and dry etching apparatus suitable for silicon carbide substrate

Abstract

The application discloses a dry etching method suitable for silicon carbide substrates, comprising the following steps: S1, placing a silicon carbide wafer on an electrostatic chuck in a reaction cavity; S2, turning on a high-voltage power supply to provide charges to the electrostatic chuck until the electrostatic chuck holds the silicon carbide wafer; S3, starting a plasma dry etching process until the plasma dry etching process is completed; and S4, turning off the high-voltage power supply of the electrostatic chuck, and separating the silicon carbide wafer from the electrostatic chuck. The dry etching method suitable for silicon carbide substrates actively reduces the contact thermal resistance by increasing the adsorption voltage, so that the electrostatic chuck can directly effectively dissipate heat of the silicon carbide wafer without using a traditional back helium cooling mode.

Description

Technical Field

[0001] This invention relates to the field of dry etching of silicon carbide substrates, and more specifically, to a dry etching method and apparatus suitable for silicon carbide substrates. Background Technology

[0002] Silicon carbide (SiC), as a typical representative of third-generation semiconductor materials, possesses excellent physical properties such as a wide bandgap, high breakdown electric field, and high thermal conductivity, and has broad application prospects in the field of high-temperature, high-frequency, and high-power power electronic devices. Dry etching is a key process in the manufacturing of silicon carbide devices. Currently, most mainstream technologies follow the equipment architecture and process parameter system of dry etching for silicon-based devices. That is, during the etching process, the wafer is held in place by an electrostatic chuck (ESC), while helium gas is introduced on the back of the wafer as a heat transfer medium. This effectively conducts the high temperature generated by the plasma reaction during etching to the lower electrode, which has a cooling function, so as to achieve precise control of the wafer temperature and ensure the uniformity of the etching rate and the stability of the process.

[0003] However, silicon carbide has a Mohs hardness of 9.5, far exceeding that of single-crystal silicon. This intrinsic hardness gives the wafer strong resistance to deformation during processing. On the other hand, during the epitaxial layer growth process on the silicon carbide substrate, significant internal stress is introduced due to lattice mismatch and differences in thermal expansion coefficients between the epitaxial layer and the substrate. This internal stress accumulates and is released within the material, further exacerbating the warping deformation of the silicon carbide wafer. Compared to silicon wafers, the edge warping of silicon carbide wafers is significantly greater. The warped wafer backside cannot adhere tightly to the electrostatic chuck surface in the edge region, forming irregular gaps. These gaps directly lead to the failure of the helium seal on the backside of the edge region, resulting in a significant increase in helium leakage.

[0004] During the etching process, the distribution of leaked helium gas in the edge region within the process chamber exhibits non-uniform and unstable dynamic characteristics. This causes the local pressure field at the wafer edge to fluctuate continuously, resulting in distortion of the electric field distribution in the edge region and significantly increasing the probability of abnormal discharges. More seriously, the small electric arcs generated by these abnormal discharges have localized high energy density, forming a strong electrostatic field and plasma aggregation effect within the discharge region. This strongly electrostatically adsorbs byproduct particles generated during dry etching, causing the particles to be firmly adsorbed onto the device area surface at the wafer edge. Furthermore, the high temperature of the micro-arc can cause localized sintering or melting of the particles, forming a strong bonding layer with the wafer surface. Subsequent standard cleaning processes, such as RCA cleaning and SC-1 / SC-2 cleaning, are unable to completely remove these particles. The remaining particles directly lead to device reliability issues such as poor metallization contact and passivation layer coverage defects, severely affecting the final yield and long-term reliability of the chip. Summary of the Invention

[0005] The purpose of this invention is to provide a dry etching method and apparatus suitable for silicon carbide substrates. This dry etching method for silicon carbide substrates actively reduces contact thermal resistance by increasing the adsorption voltage, enabling the electrostatic chuck to directly and effectively dissipate heat from the silicon carbide wafer without the need for traditional back-side helium cooling.

[0006] To achieve the above objectives, the present invention provides a dry etching method suitable for silicon carbide substrates, comprising: S1. Place the silicon carbide wafer on the electrostatic chuck in the reaction chamber; S2. Turn on the high-voltage power supply to provide charge to the electrostatic chuck until the electrostatic chuck picks up the silicon carbide wafer. S3. Begin the plasma dry etching process until the plasma dry etching process is completed; S4. Turn off the high-voltage power supply to the electrostatic chuck, and the silicon carbide wafer will separate from the electrostatic chuck.

[0007] Preferably, in step 2, the adsorption voltage of the electrostatic chuck is increased by a high-voltage power supply to reduce the contact thermal resistance between the wafer and the electrostatic chuck, and the silicon carbide wafer is directly cooled by the electrostatic chuck.

[0008] Preferably, the adsorption voltage of the electrostatic chuck is set to 1500-2500V.

[0009] Preferably, in step S3, the adsorption voltage of the electrostatic chuck remains constant.

[0010] Preferably, in step S3, before starting the plasma dry etching process, the cooler is turned on to cool the electrostatic chuck.

[0011] Preferably, the cooling machine uniformly cools the surface of the electrostatic chuck.

[0012] The present invention also provides a dry etching apparatus suitable for silicon carbide substrates, including an electrostatic chuck and a high-voltage power supply electrically connected to the electrostatic chuck. The silicon carbide wafer is bonded to the upper surface of the electrostatic chuck, and the electrostatic chuck cools the electrostatic chuck.

[0013] Preferably, the dielectric layer material of the electrostatic chuck is aluminum nitride and / or alumina ceramic.

[0014] Preferably, it also includes a cooling machine capable of exchanging heat with the electrostatic chuck, the cooling machine cooling the side of the electrostatic chuck facing away from the silicon carbide wafer.

[0015] Preferably, the surface of the electrostatic chuck is provided with multiple raised support structures, and the silicon carbide wafer is supported by the support structures.

[0016] According to the above technical solution, this invention actively reduces contact thermal resistance by increasing the adsorption voltage, enabling the electrostatic chuck to directly and effectively dissipate heat from the silicon carbide wafer without relying on traditional back-side helium cooling. This fully utilizes the excellent thermal conductivity of silicon carbide itself, establishing a direct heat conduction channel between the electrostatic chuck and the silicon carbide wafer through high-intensity electrostatic adsorption. Heat can then be rapidly conducted to the electrostatic chuck and ultimately carried away by the cooling system. Simultaneously, by eliminating the helium cooling module, the problem of edge helium leakage caused by silicon carbide wafer warping is completely eliminated.

[0017] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0018] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a flowchart of a dry etching method suitable for silicon carbide substrates; Figure 2 This is a schematic diagram of a dry etching apparatus suitable for silicon carbide substrates.

[0019] Explanation of reference numerals in the attached figures 10. Silicon carbide wafers; 2. High-voltage power supply; 3. Electrostatic chuck; 4. Cooling machine; 5. Nitrogen supply system Detailed Implementation The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0020] In this invention, unless otherwise stated, directional terms included in the terminology represent only the orientation of the term in its normal use or as commonly understood by those skilled in the art, and should not be regarded as a limitation on the term.

[0021] See Figure 1 The aforementioned dry etching method for silicon carbide substrates includes: S1. Place the silicon carbide wafer 10 on the electrostatic chuck 3 in the reaction chamber; The silicon carbide wafer 10 is placed on the electrostatic chuck 3 in the reaction chamber.

[0022] Preferably, the surface of the electrostatic chuck 3 is provided with multiple raised support structures, the back side of the silicon carbide wafer 10 contacts the top of these support structures, and grooves are formed between the support structures.

[0023] The silicon carbide wafer 10 itself has warpage due to epitaxial growth and is not perfectly flat. When the wafer is subjected to high-pressure adsorption, the raised support structure provides elastic support points for the wafer. Under the action of strong electrostatic force, the wafer is forced flattened and tightly adhered to the tops of these raised points. Moreover, by setting up the support structure, a controllable micro-gap is formed between the back side of the wafer and the surface of the chuck. During high-pressure adsorption, these gaps are compressed, but this prevents the wafer from being directly adsorbed onto a solid plane, thus preventing the wafer from breaking during adsorption due to the inability to release warpage stress. Furthermore, these raised support structures are in direct contact with the wafer, directly exchanging heat with the wafer surface.

[0024] If particles generated during dry etching fall onto a flat surface, they can easily be adsorbed and pressed into the back of the wafer.

[0025] Since the actual contact surface between the wafer and the electrostatic chuck is limited to the top of the support structure, most of the particles generated during the dry etching process will fall into the groove and will not come into contact with the back of the wafer, thus reducing the problem of particles adhering tightly to the wafer surface.

[0026] S2. Turn on the high voltage power supply 2 to provide charge to the electrostatic chuck 3 until the electrostatic chuck 3 picks up the silicon carbide wafer 10. The high-voltage power supply 2 is turned on, providing charge to the internal electrodes of the electrostatic chuck 3. After applying a DC voltage to the internal electrodes of the electrostatic chuck 3, an induced electrostatic charge is generated on the surface of the electrostatic chuck 3, and an induced charge of opposite polarity is generated on the back side of the silicon carbide wafer 10, thereby generating an electrostatic attraction force between the electrostatic chuck 3 and the silicon carbide wafer 10. As the high-voltage power supply 2 continues to supply power, the electrostatic attraction force gradually increases until the electrostatic chuck 3 firmly adheres the silicon carbide wafer 10 to its surface. Compared with traditional mechanical clamping methods, the electrostatic attraction method allows the entire back side of the silicon carbide wafer 10 to be tightly bonded to the surface of the electrostatic chuck 3.

[0027] After the silicon carbide wafer 10 and the electrostatic chuck 3 come into contact, their contact surfaces cannot perfectly fit together on a microscopic scale; they are filled with tiny air gaps. Heat passing through this interface generates significant thermal resistance.

[0028] The high voltage applied to the electrostatic chuck 3 by the high-voltage power supply 2 generates a strong electrostatic force, which presses the contact surfaces of the silicon carbide wafer 10 and the electrostatic chuck 3 together. This reduces microscopic roughness peaks, allowing for more effective contact in more areas and opening up more direct channels for heat transfer. Silicon carbide (SiC) itself is a material with high thermal conductivity. This means that once heat is effectively conducted to the electrostatic chuck 3, it can be quickly carried away. Therefore, increasing the voltage of electrostatic adsorption ensures that this efficient heat conduction path is unobstructed, effectively improving the reliability of heat dissipation from the silicon carbide wafer 10 via the electrostatic chuck 3.

[0029] S3. Begin the plasma dry etching process until the plasma dry etching process is completed; The plasma generator is activated to produce etching plasma within the reaction chamber, initiating the plasma dry etching process. During etching, the plasma anisotropically etches the surface of the silicon carbide wafer 10. The high temperature generated during etching is conducted through the silicon carbide wafer 10 to the electrostatic chuck 3, where the heat is then dissipated through its own thermal conductivity structure and cooling system. Once the predetermined plasma dry etching process is completed, i.e., the target etching depth or target etching time is reached, the plasma generator is stopped, thus halting the plasma dry etching process.

[0030] S4. Turn off the high voltage power supply 2 of the electrostatic chuck 3, and the silicon carbide wafer 10 separates from the electrostatic chuck 3.

[0031] Turn off the high-voltage power supply 2 and stop supplying power to the electrostatic chuck 3. The charge inside the electrostatic chuck 3 gradually dissipates, and the electrostatic attraction weakens and eventually disappears, causing the silicon carbide wafer 10 to separate naturally from the electrostatic chuck 3. Subsequently, the silicon carbide wafer 10 can be removed from the reaction chamber.

[0032] Therefore, the dry etching method for silicon carbide substrates of the present invention eliminates the step of introducing helium gas onto the back of the wafer in the traditional process, fundamentally avoiding the edge helium leakage problem caused by silicon carbide wafer warping. Since there is no longer any instability in edge helium pressure, the electric field distribution in the edge region will not be distorted, and the probability of abnormal discharge (micro-arc discharge) is significantly reduced. Simultaneously, because the electrostatic adsorption of etching byproduct particles by the micro-arc is eliminated, the particles will not be firmly adsorbed to the wafer edge, and the subsequent cleaning process can effectively remove residual particles, significantly improving the final chip yield.

[0033] In this embodiment, preferably, in step 2, the adsorption voltage of the electrostatic chuck 3 is increased by the high-voltage power supply 2 to reduce the contact thermal resistance between the wafer and the electrostatic chuck 3, and the wafer is directly cooled by the electrostatic chuck 3.

[0034] The adsorption voltage applied by the high-voltage power supply 2 to the electrostatic chuck 3 is set to be higher than the adsorption voltage used in conventional silicon-based dry etching processes. The adsorption force is proportional to the square of the voltage; therefore, by increasing the adsorption voltage, the electrostatic adsorption force of the electrostatic chuck 3 on the silicon carbide wafer 10 is significantly enhanced.

[0035] After the silicon carbide wafer 10 is more tightly pressed onto the upper surface of the electrostatic chuck 3, the microscopic gap between the two is effectively compressed. At the microscopic level, the support structures of the tiny protrusions on the back side of the silicon carbide wafer 10 and the surface of the electrostatic chuck 3 are flattened and compacted, greatly increasing the actual contact area for heat conduction. Moreover, the remaining microscopic air gap between the silicon carbide wafer 10 and the electrostatic chuck 3 is further reduced, resulting in a significant reduction in the contact thermal resistance between the silicon carbide wafer 10 and the electrostatic chuck 3. The reduction in contact thermal resistance means that during plasma dry etching, the heat accumulated on the silicon carbide wafer 10 can be more efficiently conducted to the electrostatic chuck 3 through the interface, and then carried away from the system by the heat-conducting structure and cooling system of the electrostatic chuck 3 itself.

[0036] Therefore, by actively reducing the contact thermal resistance by increasing the adsorption voltage, the electrostatic chuck 3 can directly and effectively dissipate heat from the silicon carbide wafer 10 without relying on the traditional back-side helium cooling method. This fully utilizes the excellent thermal conductivity of silicon carbide itself. Through high-intensity electrostatic adsorption, the electrostatic chuck 3 and the silicon carbide wafer 10 are directly connected to form a heat conduction channel, allowing heat to be rapidly conducted to the electrostatic chuck 3 and ultimately carried away by the cooling system. Simultaneously, by eliminating the helium cooling module, the problem of edge helium leakage caused by the warping of the silicon carbide wafer 10 is completely eliminated.

[0037] In this embodiment, preferably, the adsorption voltage of the electrostatic chuck 3 is set to 1500-2500V.

[0038] In traditional silicon-based dry etching processes, the commonly used adsorption voltage is typically 800V to 1600V, which can generate sufficiently strong electrostatic adsorption force. According to relevant research, for every 500V increase in the electrostatic adsorption voltage, the contact thermal resistance of the silicon carbide interface can be reduced by approximately 40%. Moreover, when the adsorption voltage exceeds 1800V, the interface thermal resistance still maintains a significant reduction, which has a significant compensating effect on heat conduction efficiency. Therefore, by setting the adsorption voltage of the electrostatic chuck 3 to 1500-2500V, the electrostatic chuck 3 can not only provide reliable electrostatic adsorption force but also effectively reduce contact thermal resistance, enabling the electrostatic chuck 3 to reliably cool the silicon carbide wafer 10 through heat transfer during the etching process.

[0039] The upper limit of the voltage range, 2500V, fully considers the voltage resistance of the electrostatic chuck 3's own material and the safety of the equipment. Controlling the adsorption voltage below 2500V can effectively avoid problems such as insulation layer breakdown and aggravated abnormal discharge caused by excessive voltage in the electrostatic chuck 3.

[0040] Therefore, setting the adsorption voltage within the preferred range of 1500V to 2500V ensures that there is a sufficiently large electrostatic adsorption force between the silicon carbide wafer 10 and the electrostatic chuck 3 to reduce the contact thermal resistance, while avoiding the risks of insulation breakdown and aggravated abnormal discharge caused by excessive voltage.

[0041] In this embodiment, preferably, the adsorption voltage of the electrostatic chuck 3 is kept constant in step S3.

[0042] By maintaining a constant adsorption voltage during the main etching stage, the electrostatic adsorption force on the silicon carbide wafer 10 remains stable throughout the etching process. Stable adsorption force means that the interfacial contact state between the silicon carbide wafer 10 and the electrostatic chuck 3 remains constant, and the contact thermal resistance does not change throughout the etching process, thus ensuring the stability of the heat conduction path. This helps maintain the uniformity of the temperature distribution on the silicon carbide wafer 10, thereby ensuring the uniformity of the etching rate and the repeatability of the etching results.

[0043] In this embodiment, preferably, in step S3, before starting the plasma dry etching process, the cooler 4 is turned on to cool the electrostatic chuck 3.

[0044] Before starting the plasma generation device for the plasma dry etching process, the cooler 4 is turned on. The cooler 4 is connected to the electrostatic chuck 3 via a coolant circulation pipeline. After the cooler 4 is turned on, the low-temperature coolant enters the cooling channel inside the electrostatic chuck 3 through the inlet pipe of the coolant circulation pipeline. As the coolant flows through the cooling channel, it exchanges heat with the substrate of the electrostatic chuck 3, absorbing heat and lowering its temperature. The coolant, having absorbed heat, returns to the cooler 4 through the outlet pipe, where it is cooled again and reused.

[0045] In this embodiment, preferably, the cooling machine 4 uniformly cools the surface of the electrostatic chuck 3.

[0046] By uniformly cooling the electrostatic chuck 3, the temperature of each area on the adsorption surface of the electrostatic chuck 3 is ensured to remain highly consistent. This uniform cooling effect is transferred to the silicon carbide wafer 10, resulting in a more uniform temperature distribution across different areas of the silicon carbide wafer 10. In dry etching processes, temperature is one of the key parameters determining the chemical reaction rate. The temperature uniformity of the silicon carbide wafer 10 directly determines the uniformity of the etching rate. If there is temperature unevenness on the surface of the electrostatic chuck 3, it will lead to differences in etching depth and sidewall profile in different areas of the silicon carbide wafer 10, ultimately affecting device performance and product yield. To achieve uniform cooling, this embodiment employs one or more of the following techniques.

[0047] In one embodiment, the design of the cooling channels ensures uniform cooling of the surface of the electrostatic chuck 3. The distance between the cooling channels and the adsorption surface of the electrostatic chuck 3 changes with position along the path from the coolant inlet to the outlet. Specifically, considering that the coolant gradually heats up during flow, resulting in the lowest temperature at the inlet and the highest temperature at the outlet, the distance between the cooling channels and the adsorption surface is designed to gradually decrease in the later stages of the coolant flow. This shortened heat transfer distance compensates for the decrease in cooling effect caused by the increased coolant temperature, thereby making the temperature distribution across the entire adsorption surface of the electrostatic chuck 3 more uniform.

[0048] In one embodiment, heat exchange components are disposed on the channel wall of the cooling channel. These heat exchange components are arranged sequentially at intervals along the extension direction of the cooling channel. These heat exchange components can increase the contact area between the coolant and the channel wall, while simultaneously enhancing the flow disturbance of the coolant, breaking the laminar flow state to form turbulent flow, and significantly improving heat exchange efficiency. More importantly, the heat exchange components can be selectively arranged on the surface of the electrostatic chuck 3 in areas requiring increased cooling effect, thereby enhancing cooling of these areas and balancing the overall temperature difference.

[0049] In one embodiment, multiple independent cooling fluid channels are provided. The electrostatic chuck 3 has at least two cooling fluid channels internally, each channel being independent of the others and connected to different cooling fluid sources. By independently controlling the coolant flow rate and temperature of each channel, differentiated temperature control for different regions can be achieved. For example, for the edge region of the silicon carbide wafer 10, which has more severe warping and potentially poorer thermal conductivity, corresponding to the edge region of the electrostatic chuck 3, the coolant flow rate or coolant temperature in the edge region of the electrostatic chuck 3 can be increased to enhance edge cooling.

[0050] The present invention also provides a dry etching apparatus suitable for silicon carbide substrates, including an electrostatic chuck 3 and a high-voltage power supply 2 electrically connected to the electrostatic chuck 3. The silicon carbide wafer 10 is attached to the upper surface of the electrostatic chuck 3, and the electrostatic chuck 3 cools the electrostatic chuck 3.

[0051] An electrostatic chuck 3 is disposed inside the reaction chamber to support and adsorb the silicon carbide wafer 10. The upper surface of the electrostatic chuck 3 is the adsorption surface, on which the silicon carbide wafer 10 is placed and adheres to the adsorption surface. A high-voltage power supply 2 provides a DC high-voltage charge to the internal electrodes of the electrostatic chuck 3. When the high-voltage power supply 2 is turned on, a high voltage is applied to the internal electrodes of the electrostatic chuck 3, generating an electrostatic charge on the surface of the electrostatic chuck 3. The back side of the silicon carbide wafer 10 is induced with a charge of opposite polarity, thereby generating an electrostatic adsorption force to adsorb and fix the silicon carbide wafer 10. The silicon carbide wafer 10 is in close contact with the upper surface of the electrostatic chuck 3. The heat of the silicon carbide wafer 10 is conducted to the electrostatic chuck 3 through the interface and then carried away by the cooling structure, thereby achieving indirect cooling of the silicon carbide wafer 10.

[0052] Alternatively, a dry etching apparatus suitable for silicon carbide substrates can be obtained by modifying a traditional dry etching apparatus. When modifying a traditional dry etching apparatus, it is only necessary to add a high-voltage power supply 2 and connect the high-voltage power supply 2 to the electrostatic chuck 3. The existing nitrogen supply system 5 can be retained, but the nitrogen supply valve can be closed.

[0053] In this embodiment, preferably, the dielectric layer material of the electrostatic chuck 3 is aluminum nitride or aluminum oxide ceramic.

[0054] The dielectric layer of the electrostatic chuck 3 is made of aluminum nitride ceramic or alumina ceramic. Both of these materials are highly insulating ceramic materials with good dielectric properties, mechanical strength, and chemical stability.

[0055] Alumina ceramic is a classic dielectric layer material in the field of electrostatic chucks. Alumina ceramic possesses excellent insulation properties, effectively achieving high-voltage isolation to ensure stable operation of electrostatic adsorption. Simultaneously, alumina ceramic exhibits excellent mechanical strength and hardness, providing a robust and durable substrate for the electrostatic chuck. Furthermore, alumina ceramic demonstrates excellent chemical stability, reliably withstanding various harsh process environments. The moderate dielectric constant and low dielectric loss of alumina ceramic effectively enhance charge density.

[0056] Compared to alumina ceramics, aluminum nitride ceramics exhibit higher thermal conductivity and better thermal stability. For the processing of silicon carbide wafer 10, due to the high hardness and good thermal conductivity of silicon carbide material, and the relatively high heat flux density during etching, using aluminum nitride ceramics as the dielectric layer material for the electrostatic chuck 3 can achieve better temperature control uniformity and faster thermal response. Aluminum nitride ceramics also possess high dielectric strength (>15kV / mm), sufficient to withstand the 1500V to 2500V adsorption voltage described in this application without breakdown failure.

[0057] In one specific implementation, for silicon carbide etching processes with ordinary power density, alumina ceramic can be used as the dielectric layer material of the electrostatic chuck 3 to meet the requirements; for silicon carbide etching processes with high power density and high heat flux density, aluminum nitride ceramic is preferably used as the dielectric layer material of the electrostatic chuck 3.

[0058] Using aluminum nitride or alumina ceramic as the dielectric layer material of the electrostatic chuck 3 ensures the insulation reliability and long-term operational stability of the electrostatic chuck 3 under high voltage conditions (1500V to 2500V). The high thermal conductivity of aluminum nitride ceramic further enhances the heat dissipation capacity of the electrostatic chuck 3, enabling heat to be conducted more quickly to the cooling structure and carried away within the electrostatic chuck 3.

[0059] In this embodiment, preferably, a cooling machine 4 is also included, which is capable of exchanging heat with the electrostatic chuck 3, and the cooling machine 4 cools the side of the electrostatic chuck 3 facing away from the silicon carbide wafer 10.

[0060] The electrostatic chuck 3 has an internal cooling channel located within its substrate, near the back side. Low-temperature coolant supplied by the cooling unit 4 enters the cooling channel through an inlet pipe. As the coolant flows through the cooling channel, it exchanges heat with the substrate material of the electrostatic chuck 3—absorbing heat from the chuck and lowering its temperature. The cooled coolant, now at a higher temperature, returns to the cooling unit 4 through an outlet pipe. Inside the cooling unit 4, the high-temperature coolant is further cooled by the refrigeration system and then re-enters the electrostatic chuck 3 through the inlet pipe, creating a circulating cooling system.

[0061] The cooling device 4 cools the electrostatic chuck 3 itself, rather than directly cooling the silicon carbide wafer 10. In the heat transfer path, the contact thermal resistance between the silicon carbide wafer 10 and the electrostatic chuck 3 is one of the key factors determining the heat dissipation efficiency, and this application effectively reduces the thermal resistance of this step by increasing the adsorption voltage.

[0062] The high-temperature heat generated during the etching process of the silicon carbide wafer 10 is sequentially conducted through the interface to the electrostatic chuck 3, then conducted inside the electrostatic chuck 3 to the cooling channels, carried away by the circulating coolant, and finally dissipated in the cooling machine 4. This heat dissipation path does not rely on helium heat transfer on the back side of the wafer, thus completely avoiding the helium leakage problem caused by the warping of the silicon carbide wafer 10. The continuous cooling of the back side of the electrostatic chuck 3 by the cooling machine 4 ensures that the electrostatic chuck 3 remains at a low temperature throughout the etching process, providing stable and reliable heat dissipation conditions for the silicon carbide wafer 10.

[0063] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0064] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0065] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A dry etching method suitable for silicon carbide substrates, characterized in that, include: S1. Place the silicon carbide wafer (10) on the electrostatic chuck (3) in the reaction chamber; S2. Turn on the high voltage power supply (2) to provide charge to the electrostatic chuck (3) until the electrostatic chuck (3) attracts the silicon carbide wafer (10). S3. Begin the plasma dry etching process until the plasma dry etching process is completed; S4. Turn off the high voltage power supply (2) of the electrostatic chuck (3) and the silicon carbide wafer (10) is separated from the electrostatic chuck (3).

2. The dry etching method for silicon carbide substrates according to claim 1, characterized in that, In step 2, the adsorption voltage of the electrostatic chuck (3) is increased by the high voltage power supply (2), the contact thermal resistance between the wafer and the electrostatic chuck (3) is reduced, and the silicon carbide wafer is directly cooled by the electrostatic chuck (3).

3. The dry etching method for silicon carbide substrates according to claim 2, characterized in that, The adsorption voltage of the electrostatic chuck (3) is set to 1500-2500V.

4. The dry etching method for silicon carbide substrates according to claim 2, characterized in that, In step S3, the adsorption voltage of the electrostatic chuck (3) remains constant.

5. The dry etching method for silicon carbide substrates according to claim 1, characterized in that, In step S3, before starting the plasma dry etching process, the cooler (4) is turned on to cool the electrostatic chuck (3).

6. The dry etching method for silicon carbide substrates according to claim 5, characterized in that, The cooling machine (4) uniformly cools the surface of the electrostatic chuck (3).

7. A dry etching apparatus suitable for silicon carbide substrates, characterized in that, Includes the electrostatic chuck (3) and a high-voltage power supply (2) electrically connected to the electrostatic chuck (3), with the silicon carbide wafer (10) attached to the upper surface of the electrostatic chuck (3).

8. The dry etching apparatus for silicon carbide substrates according to claim 7, characterized in that, The dielectric layer material of the electrostatic chuck (3) is aluminum nitride and / or alumina ceramic.

9. The dry etching apparatus for silicon carbide substrates according to claim 7, characterized in that, It also includes a cooling machine (4) capable of exchanging heat with the electrostatic chuck (3), the cooling machine (4) cooling the side of the electrostatic chuck (3) facing away from the silicon carbide wafer (10).

10. The dry etching apparatus for silicon carbide substrates according to claim 7, characterized in that, The surface of the electrostatic chuck (3) is provided with a plurality of raised support structures, and the silicon carbide wafer is supported by the support structures.

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