A polishing system and method for gallium nitride materials

Abstract

This invention relates to the field of polishing technology, and more particularly to a polishing system and method for gallium nitride (GaN) materials. The polishing system for GaN materials includes an environment displacement device and a plasma generator. The environment displacement device includes an environment displacement chamber, a vacuum pump unit, a gas delivery unit, and a voltage stabilizing unit. The plasma generator includes an inductively coupled plasma generator unit and a gas supply unit disposed within the environment displacement chamber. The environment displacement chamber is evacuated by the vacuum pump unit, and then filled with an inert protective gas by the gas delivery unit to ensure an oxygen-free atmosphere. Then, within the inert protective gas atmosphere of the environment displacement chamber, plasma is generated by the inductively coupled plasma generator unit to polish the GaN surface. After polishing, the surface is cooled within the environment displacement chamber, thereby preventing the GaN from being oxidized during the high-temperature reaction process and during cooling, which would otherwise lead to surface roughness deterioration.

Description

Technical Field

[0001] This invention relates to the field of polishing technology, and more particularly to a polishing system and method for gallium nitride materials. Background Technology

[0002] Gallium nitride (GaN), as one of the representative materials of third-generation semiconductors, has excellent electrical properties such as high temperature resistance, high voltage resistance, and high frequency. It is widely used in high electron mobility transistors (HEMT), light-emitting diodes (LEDs), and power and radio frequency electronic devices. In order to obtain better performance of gallium nitride devices, the surface of gallium nitride needs to achieve nanoscale smoothness.

[0003] Currently, the main processes used for GaN polishing include chemical-mechanical polishing (CMP) and plasma-assisted polishing. Among them, chemical-mechanical polishing has a low material removal rate and is prone to forming etching pits on the surface, and the polishing slurry used is also prone to causing environmental pollution; while plasma-assisted polishing can reduce the surface roughness of gallium nitride to Sq0.08nm, but the material removal efficiency is only 200nm / h.

[0004] Plasma-based atom-selective etching (PASE) is an advanced semiconductor surface polishing technique. In existing technologies, using PASE to polish GaN surfaces under atmospheric conditions reduces the surface roughness from Sa 135.8 nm to Sa 2.68 nm, with a material removal rate reaching 93.01 μm / min. Although PASE polishing of GaN surfaces offers extremely high material removal efficiency, the GaN material is at a high temperature after PASE polishing, making it highly susceptible to oxidation by atmospheric oxygen, leading to deterioration of surface roughness. Furthermore, ordinary sealed cavities cannot withstand the continuous gas intake conditions of ICP (Inductively Coupled Plasma) processes.

[0005] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the purpose of this invention is to provide a polishing system and method for gallium nitride materials, which aims to solve the problem that gallium nitride materials processed by existing polishing systems are easily oxidized by oxygen in the atmospheric environment, resulting in deterioration of surface roughness.

[0007] The technical solution of the present invention is as follows: On one hand, the present invention provides a polishing system for gallium nitride materials, including an environmental displacement device and a plasma generator; The environmental replacement device includes an environmental replacement chamber, a vacuum pump unit for evacuating the environmental replacement chamber, a gas delivery unit for delivering inert gas to the environmental replacement chamber, and a pressure stabilizing unit for maintaining the pressure of the environmental replacement chamber. The plasma generating device includes an inductively coupled plasma generating unit disposed within the environmental displacement chamber and a gas supply unit for providing working gas to the inductively coupled plasma generating unit.

[0008] Preferably, in the polishing system for gallium nitride materials, the environmental displacement device further includes a vacuum gauge disposed outside the environmental displacement cavity for feedback on the vacuum level inside the environmental displacement cavity; the environmental displacement cavity is provided with a door; and the door is provided with an observation window.

[0009] Preferably, in the polishing system for gallium nitride materials, the vacuum pump unit includes a vacuum pump and a vacuum extraction pipe for connecting the vacuum pump to the environmental displacement chamber; the gas delivery unit includes an inert gas storage tank and an inert gas delivery pipe for connecting the inert gas storage tank to the environmental displacement chamber, and a control valve is provided at the connection between the inert gas storage tank and the inert gas delivery pipe.

[0010] Preferably, in the polishing system for gallium nitride materials, the inductively coupled plasma generating unit includes a radio frequency power supply, a matching device electrically connected to the radio frequency power supply, an induction coil electrically connected to the matching device, a torch tube disposed within the induction coil, and an electric spark generator for generating an electric spark within the torch tube.

[0011] Preferably, in the polishing system for gallium nitride materials, the torch tube includes a torch tube mounting head disposed on the inner wall of the environmental displacement chamber, an inner torch tube and an outer torch tube coaxially mounted on the torch tube mounting head; the induction coil is disposed around the outer side of the outer torch tube.

[0012] Preferably, the polishing system for gallium nitride materials further includes a three-axis motion platform disposed below the torch tube; the voltage stabilizing unit is located on the side of the three-axis motion platform near the torch tube; the voltage stabilizing unit includes a voltage stabilizing and suction base, a pressure feedback control system, and a voltage stabilizing and suction guide shroud that matches the voltage stabilizing and suction base and is coaxially disposed on the end of the torch tube near the three-axis motion platform.

[0013] Preferably, the polishing system for gallium nitride materials further includes a cooling device; the cooling device includes a chiller and a cooling water pipe connected to the chiller; the cooling water pipe is arranged along the radio frequency power supply, the matching unit, the environmental displacement cavity, the induction coil, and the torch tube.

[0014] Preferably, in the polishing system for gallium nitride materials, the gas supply unit includes a cooling gas storage tank, a reaction gas storage tank, and a carrier gas storage tank; the cooling gas storage tank, the reaction gas storage tank, and the carrier gas storage tank are respectively connected to the inductively coupled plasma generating unit via pipelines.

[0015] On the other hand, the present invention also provides a polishing method for gallium nitride materials, comprising the steps of: Gallium nitride material is placed in an environmental replacement chamber, the environmental replacement chamber is evacuated, and then an inert gas is injected into the environmental replacement chamber. Provide cooling gas for the inductively coupled plasma generation unit; After providing the reactive gas and carrier gas to the inductively coupled plasma generating unit, and turning on the radio frequency power supply, matching unit and electric spark generator, the inductively coupled plasma generating unit excites plasma to polish the gallium nitride material.

[0016] Preferably, in the gallium nitride material polishing method, the cooling gas is argon; the reaction gas is carbon tetrafluoride; the carrier gas is argon; and the inert gas is nitrogen.

[0017] Beneficial Effects: This invention provides a polishing system and method for gallium nitride (GaN) materials. The polishing system includes an environmental displacement device and a plasma generator. The environmental displacement device includes an environmental displacement chamber, a vacuum pump unit for evacuating the environmental displacement chamber, a gas delivery unit for supplying inert gas to the environmental displacement chamber, and a pressure stabilizing unit for maintaining the pressure of the environmental displacement chamber. The plasma generator includes an inductively coupled plasma (ICP) generator disposed within the environmental displacement chamber and a gas supply unit for supplying working gas to the ICP generator. This invention uses the vacuum pump unit to evacuate the air in the environmental displacement chamber, and then uses the gas delivery unit to fill the environmental displacement chamber with inert protective gas, ensuring an oxygen-free environment. Then, within the inert protective gas atmosphere of the environmental displacement chamber, the ICP generator generates plasma to polish the GaN surface. After polishing, the surface is cooled within the environmental displacement chamber, thereby preventing the GaN from being oxidized during the high-temperature reaction process and during cooling, which would otherwise lead to surface roughness deterioration. Meanwhile, the pressure stabilizing unit can maintain a stable pressure within the environmental displacement chamber during the polishing process, and the pressure can be adjusted in real time. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of a polishing system for gallium nitride materials according to the present invention; Figure 2 This is a schematic diagram of the internal structure of the environmental displacement cavity in the polishing system for gallium nitride materials described in this invention; Figure 3 This is a schematic diagram of a polishing method for gallium nitride materials; Figure 4 The image shows the AFM characterization results of polishing GaN sample 1 and GaN sample 2 using the polishing system of the present invention in Example 1. Explanation of reference numerals in the attached drawings: 11. Environment replacement chamber; 111. Door; 112. Observation window; 12. Vacuum pump unit; 121. Vacuum pump; 122. Vacuum pump pipe; 13. Gas delivery unit; 131. Inert gas storage tank; 132. Inert gas delivery pipe; 14. Pressure stabilizing unit; 141. Pressure stabilizing pump base; 142. Pressure stabilizing pump guide hood; 143. Pressure stabilizing pump; 144. Vacuum gauge; 15. Vacuum breaking valve; 16. Inductively coupled plasma generator. Components 21, RF power supply 211, matching unit 212, induction coil 213, torch tube 214, torch tube mounting head 2141, external torch tube 2142, electric spark generator 215, gas supply unit 22, cooling gas storage tank 221, reaction gas storage tank 222, carrier gas storage tank 223, flow meter 224, collection box 30, three-axis motion platform 40, three-axis control touch screen 41, cooling device 50, chiller 51, cooling water pipe 52. Detailed Implementation

[0019] This invention provides a polishing system and method for gallium nitride materials. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0020] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," and "rear," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application 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, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of the stated features.

[0021] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0022] like Figure 1 As shown, the present invention provides a polishing system for gallium nitride materials, including an environmental displacement device and a plasma generator; The environmental replacement device includes an environmental replacement chamber 11, a vacuum pump unit 12 for evacuating the environmental replacement chamber 11, a gas delivery unit 13 for delivering inert gas to the environmental replacement chamber 11, and a pressure stabilizing unit 14 for maintaining the pressure of the environmental replacement chamber 11. The plasma generating device includes an inductively coupled plasma generating unit 21 disposed in the environmental displacement chamber 11 and a gas supply unit 22 for providing working gas to the inductively coupled plasma generating unit 21.

[0023] In this embodiment, the vacuum pump unit 12 evacuates the air in the environmental replacement chamber 11 to a vacuum, and then the gas delivery unit 13 fills the environmental replacement chamber 11 with an inert protective gas to ensure that the ambient atmosphere is oxygen-free. Then, within the inert protective gas atmosphere of the environmental replacement chamber, the inductively coupled plasma generator 21 generates plasma to polish the gallium nitride surface. After polishing, the surface is cooled within the environmental replacement chamber, thus preventing the gallium nitride from being oxidized during the high-temperature reaction and cooling processes, which would otherwise lead to surface roughness deterioration. Simultaneously, the voltage stabilizing unit 14 maintains a stable pressure within the environmental replacement chamber during the polishing process and allows for real-time pressure adjustment.

[0024] Specifically, based on the polishing system, the GaN material is first placed in an appropriate position within the environmental displacement chamber 11. The air in the environmental displacement chamber 11 is then evacuated to below 1 kPa using the vacuum pump unit 12. An inert protective gas is then introduced into the environmental displacement chamber 11 using the gas delivery unit 13. The gas supply unit 22 provides the inductively coupled plasma generating unit 21 with a working gas comprising cooling gas, reactive gas, and carrier gas. The inductively coupled plasma generating unit 21 is then activated to excite plasma, which is used to polish the GaN material. Furthermore, from the start of plasma excitation until the entire surface polishing process of the GaN material, the working gas comprising cooling gas, reactive gas, and carrier gas is continuously supplied through the gas supply unit 22. This means that the gas content in the environmental displacement chamber 11 continuously increases, causing the gas pressure within the environmental displacement chamber 11 to continuously rise. The present invention utilizes the pressure stabilizing unit 14 to appropriately extract some gas based on the pressure within the environmental displacement chamber 11, maintaining the pressure within the environmental displacement chamber 11.

[0025] Furthermore, the polishing system for gallium nitride (GaN) materials utilizes an environmental displacement plasma etching method to process the surface of GaN and modify its roughness, achieving a polishing effect. Using this system not only solves the high-temperature oxidation problem in GaN polishing but also, through a unique voltage stabilizing unit, addresses the issues of unstable etching rates caused by reaction product accumulation in a sealed cavity and potential surface contamination. This lays the hardware foundation for the stable fabrication of atomically smooth surfaces.

[0026] In some embodiments, the environmental replacement device further includes a vacuum gauge 15 disposed outside the environmental replacement chamber 11 for feedback on the vacuum level inside the environmental replacement chamber 11. During the vacuuming phase, the vacuum gauge 15 can be used to visually confirm whether the vacuum pump unit 11 is working properly and whether the environmental replacement chamber 11 is leaking. When the pointer or value reaches the set value, the vacuuming phase is completed. Then, the gas delivery unit 13 is used to deliver inert gas into the environmental replacement chamber 11, so that the pointer or value of the vacuum gauge reaches the preset value.

[0027] In some embodiments, the environment replacement chamber 11 is provided with a hatch 111; the hatch 111 is provided with an observation window 112. The observation window 112 allows for easy observation of the polishing process within the environment replacement chamber 11 at any time.

[0028] In some embodiments, the observation window 112 is made of high-temperature resistant glass; preferably, the observation window 112 is made of quartz or sapphire.

[0029] In some embodiments, the environmental replacement chamber 11 is formed by a sealed assembly of an open shell and a hatch 111. The hatch 111 is movably connected to the side of the shell on one side, facilitating the placement and removal of gallium nitride material. A sealing strip is provided between the hatch 111 and the shell, giving the environmental replacement chamber 111 a high degree of airtightness.

[0030] In some embodiments, the vacuum pump unit 12 includes a vacuum pump 121 and a vacuum extraction pipe 122 for connecting the vacuum pump 121 to the environment replacement chamber 11; by using the cooperation of the vacuum pump 121 and the vacuum extraction pipe 122, the environment replacement chamber 11 can be evacuated so that the environment replacement chamber 11 is free of air.

[0031] In some embodiments, the gas delivery unit 13 includes an inert gas storage tank 131 and an inert gas delivery pipe 132 for connecting the inert gas storage tank 131 to the environment replacement chamber 11. A control valve (not shown) is provided at the connection between the inert gas storage tank 131 and the inert gas delivery pipe 132. By using the inert gas storage tank 131 to deliver inert gas into the environment replacement chamber 11 through the inert gas delivery pipe 132, the environment replacement chamber 11 can be kept oxygen-free, avoiding the deterioration of gallium nitride surface roughness caused by thermal oxidation at high temperatures after polishing. The control valve at the connection between the inert gas storage tank 131 and the inert gas delivery pipe 132 allows for reasonable control of the gas pressure within the environment replacement chamber 11, preventing the danger of chamber rupture due to excessive pressure.

[0032] In some embodiments, a vacuum breaking valve 16 is provided on the side wall of the environmental replacement chamber 11 for injecting atmospheric pressure air after polishing and cooling. The vacuum breaking valve 16 is spring-loaded and has the advantages of flexible setting, leak-proof micro-vacuum, vibration resistance to prevent accidental opening, and remote strong breaking.

[0033] In some embodiments, the inductively coupled plasma generating unit 21 includes a radio frequency (RF) power supply 211, a matching device 212 electrically connected to the RF power supply 211, an induction coil 213 electrically connected to the matching device 212, a torch tube 214 disposed within the induction coil 213, and an electric spark generator 215 for generating an electric spark within the torch tube 214. The RF power supply 211 generates RF power at a fixed frequency; the matching device 212 performs a bidirectional impedance transformation function, providing a fixed pure resistance port facing the RF power supply 211 to ensure the power supply is always at its maximum output power plane. The induction coil 213, acting as a nonlinear load, obtains maximum high-frequency current under the drive of the matching device, ultimately achieving low-reflection, high-efficiency, and stable transmission of RF energy to the plasma. The electric spark generator 215 can be used to excite plasma in an argon gas flow, allowing the subsequent high-frequency induction field to be coupled with a conductive medium, thereby smoothly drawing kilowatt-level RF power into the reactant gas to form a stable torch flame.

[0034] In some embodiments, the polishing system for gallium nitride materials further includes a collection box 30 located below the environmental displacement device for integrating functional devices; the collection box 30 is provided with several mounting slots for mounting the functional devices; preferably, the radio frequency power supply 211 and the electric spark generator are both disposed within the mounting slots. Integrating functional devices using the collection box 30 can improve the integration level of the polishing system and reduce its space occupancy.

[0035] In some embodiments, a plurality of evenly distributed pads are provided between the environmental replacement device and the collection box, so that there is a gap between the environmental replacement device and the collection box, which is conducive to heat dissipation of the environmental replacement device and avoids thermal damage to the functional components set on the collection box, thereby extending the service life of the polishing system.

[0036] In some embodiments, the torch tube 214 includes a torch tube mounting head 2141 disposed on the inner wall of the environmental displacement chamber 11, an inner torch tube and an outer torch tube 2142 coaxially mounted on the torch tube mounting head 2141; the induction coil 213 is disposed around the outer side of the outer torch tube 2142.

[0037] Specifically, the outer torch 2142, also known as the plasma torch, is made of high-purity quartz with a wall thickness of ≥2mm. It can withstand a plasma radiation heat load of 6000-10000K and a pressure difference of 1atm, preventing thermal gradient breakage. The outer torch 2142 serves as a gas flow dynamic boundary, where high-speed tangential cooling gas forms a stable gas sheath on its inner wall, suppressing plasma arc root adhesion and reducing arc root thermal erosion. At the same time, the outer torch 2142 also serves as an electromagnetic boundary, maintaining the plasma annular volume within the induction coil region and preventing arc column expansion that could lead to inter-turn arcing in the coil.

[0038] In some embodiments, the outer torch 2142 is sleeved on the outer wall of the inner torch, and a gap is provided between the outer torch 2142 and the inner torch for introducing cooling gas.

[0039] Specifically, the gas supply unit 22 is used to tangentially introduce cooling gas into the gap between the inner torch tube and the outer torch tube 2142, and the reaction gas and carrier gas are introduced into the inner torch tube. Then, the radio frequency power supply, matching unit and electric spark generator are turned on to excite plasma by the inductively coupled plasma generation unit 21. The plasma is ejected from the end of the torch tube, thereby processing gallium nitride material and finally realizing the processing of gallium nitride material.

[0040] In some embodiments, the torch mounting head 2141 is detachably connected to the inner wall of the environmental replacement chamber 11, which facilitates subsequent maintenance and repair.

[0041] In some embodiments, the polishing system for gallium nitride materials further includes a three-axis motion platform 40 disposed below the torch tube 214; the voltage stabilizing unit 14 is located on the side of the three-axis motion platform 40 near the torch tube 214; the voltage stabilizing unit 14 includes a voltage stabilizing vacuum base 141, a pressure feedback control system (not shown), and a voltage stabilizing vacuum guide shroud 142 that matches the voltage stabilizing vacuum base 141 and is coaxially disposed on the end of the torch tube 214 near the three-axis motion platform 40. The three-axis motion platform allows the gallium nitride material to be polished, placed on the platform, to move back, forth, left, right, up, and down, improving the polishing effect; and the cooperation of the voltage stabilizing vacuum base 141 and the voltage stabilizing vacuum guide shroud 142 allows reaction products to be removed at any time.

[0042] Specifically, the reaction gas reacts with gallium nitride material to generate reaction products, which affect the polishing effect of gallium nitride material. The pressure-stabilized air extraction guide hood 142 is placed around gallium nitride material, and the negative pressure guides the airflow to carry away the products, preventing the reaction products from being deposited on the surface of gallium nitride material for the second time.

[0043] In some embodiments, the pressure-stabilizing and gas-extraction guide shroud 142 is coaxially disposed outside the torch tube, and the torch tube portion passes through the top of the pressure-stabilizing and gas-extraction guide shroud 142; the pressure-stabilizing and gas-extraction port of the pressure-stabilizing unit 14 is located at the top of the environmental displacement chamber 11, that is, above the torch tube. Since the product generated by the reaction of the reaction gas and GaN material has a high temperature, it tends to flow upward. Therefore, placing the gas-extraction port above the GaN material and the torch tube can improve the gas extraction efficiency of the reaction product.

[0044] In some embodiments, the pressure stabilizing unit further includes a pressure-stabilizing vacuum pump 143 and a pressure-stabilizing vacuum pipe 144. During the plasma reaction process, the pressure inside the environmental displacement chamber changes due to the continuous input of cooling gas, reactant gas, and carrier gas. The pressure stabilizing unit can maintain the pressure inside the chamber stable.

[0045] Specifically, since the environmental replacement chamber 11 is in a sealed state, the pressure is determined by the injected gas. A pressure stabilizing unit is provided to compensate for the gas injected during plasma polishing and regulate the internal pressure. Furthermore, the vacuum gauge 15 monitors the pressure within the environmental replacement chamber 11 in real time and feeds it back to the pressure feedback control system. This system controls the pumping rate of the pressure-stabilizing pump 143, ensuring stable pressure within the environmental replacement chamber 11. The pressure feedback control system is configured to receive the real-time pressure signal within the environmental replacement chamber and control the pumping rate of the pressure-stabilizing pump 143 based on this signal to offset the pressure increment caused by the continuous input of cooling gas, reactive gas, and carrier gas from the gas supply unit, thus maintaining a dynamic pressure balance within the environmental replacement chamber.

[0046] In some embodiments, the three-axis motion platform 40 includes a sample stage located on the pressure-stabilized vacuum base 141 and inside the pressure-stabilized vacuum guide shroud 142, a drive motor for driving the sample stage to move in the XYZ axis directions, a connector for fixing the sample stage to the drive motor, and a three-axis control touch screen 41 for controlling the drive motor.

[0047] Specifically, the sample stage is located inside the environmental replacement chamber and is used to support gallium nitride material; the position of gallium nitride can still be adjusted even when the door 111 is closed, thanks to the three-axis control touch screen 41 and the drive motor.

[0048] In some embodiments, the pressure-stabilizing air extraction guide shroud 142 has a hemispherical structure; the pressure-stabilizing air extraction guide shroud 142 is made of glass and has high temperature resistance.

[0049] In some embodiments, the polishing system for gallium nitride materials further includes a cooling device 50; the cooling device 50 includes a chiller 51 and cooling water pipes 52 connected to the chiller 51; the cooling water pipes 52 are arranged along the RF power supply 211, the matching unit 212, and the environmental displacement chamber 11. The cooling device, consisting of the chiller 51 and the cooling water pipes 52 arranged along the RF power supply 211, the matching unit 212, and the environmental displacement chamber 11, can simultaneously cool the RF power supply 211, the matching unit 212, and the environmental displacement chamber 11, achieving overall heat dissipation. Preferably, the cooling water pipes 52 are densely arranged around the environmental displacement chamber 11 and connected to the chiller 51 to achieve rapid heat dissipation.

[0050] In some embodiments, the gas supply unit 22 includes a cooling gas storage tank 221, a reaction gas storage tank 222, and a carrier gas storage tank 223; the cooling gas storage tank 221, the reaction gas storage tank 222, and the carrier gas storage tank 223 are respectively connected to the inductively coupled plasma generating unit 21 via pipelines. Argon (Ar), carbon tetrafluoride (CF4), and argon (Ar) are stored in the cooling gas storage tank 221, the reaction gas storage tank 222, and the carrier gas storage tank 223, respectively, and then the working gas is supplied to the inductively coupled plasma generating unit 21.

[0051] In some embodiments, flow meters 224 are respectively provided on the pipes connecting the cooling gas storage tank 221, the reaction gas storage tank 222, and the carrier gas storage tank 223 to the inductively coupled plasma generating unit 21, and the flow meters 224 are installed in the mounting slot of the collection box 30, thereby improving the integration of the polishing system.

[0052] Specifically, cooling gas is tangentially introduced into the gap between the inner torch tube and the outer torch tube 2142 via the cooling gas storage tank 221 through the corresponding flow meter. Then, the reaction gas and the carrier gas are introduced into the inner torch tube via the reaction gas storage tank 222 and the carrier gas storage tank 223 through the corresponding flow meter. The radio frequency power supply 211, the matching unit 212 and the electric spark generator 215 are turned on to excite plasma in the inductively coupled plasma generating unit 21. The plasma is ejected from the end of the torch tube to process gallium nitride material and polish the surface of gallium nitride material.

[0053] In addition, the present invention also provides a polishing method for gallium nitride materials, comprising the following steps: Step S10: Place the gallium nitride material in the environment replacement chamber, evacuate the environment replacement chamber, and then inject inert gas into the environment replacement chamber; Step S20: Provide cooling gas to the inductively coupled plasma generation unit; Step S30: Provide the reactive gas and carrier gas to the inductively coupled plasma generating unit, and after turning on the radio frequency power supply, matching unit and electric spark generator, the inductively coupled plasma generating unit excites plasma to polish the gallium nitride material.

[0054] In this embodiment, gallium nitride material is placed in a sealed environmental replacement chamber, and the air in the environmental replacement chamber is evacuated to below 1 kPa. Then, high-purity protective inert gas is injected into the environmental replacement chamber. Then, working gas is provided to the inductively coupled plasma generating unit through the gas supply unit. After the radio frequency power supply, matching unit and electric spark generator are turned on, the inductively coupled plasma generating unit excites plasma to polish the gallium nitride material. After polishing, cooling gas is continuously introduced into the environmental replacement chamber to cool the gallium nitride, resulting in gallium nitride material with a smooth surface.

[0055] Specifically, based on the polishing system, the GaN material is first placed in an appropriate position within the environmental displacement chamber 11. The air in the environmental displacement chamber 11 is then evacuated to below 1 kPa using the vacuum pump unit 12. An inert protective gas is then introduced into the environmental displacement chamber 11 using the gas delivery unit 13. The gas supply unit 22 provides the inductively coupled plasma generating unit 21 with a working gas comprising cooling gas, reactive gas, and carrier gas. The inductively coupled plasma generating unit 21 is then activated to excite plasma, which is used to polish the GaN material. Furthermore, from the start of plasma excitation until the entire surface polishing process of the GaN material, the working gas comprising cooling gas, reactive gas, and carrier gas is continuously supplied through the gas supply unit 22. This means that the gas content in the environmental displacement chamber 11 continuously increases, causing the gas pressure within the environmental displacement chamber 11 to continuously rise. The present invention utilizes the pressure stabilizing unit 14 to appropriately extract some gas based on the pressure within the environmental displacement chamber 11, maintaining the pressure within the environmental displacement chamber 11.

[0056] In some embodiments, the cooling gas is argon; the reactant gas is carbon tetrafluoride; the carrier gas is argon; and the inert gas is nitrogen.

[0057] In some embodiments, in step S30, after the inductively coupled plasma generating unit excites plasma to polish the gallium nitride material, cooling gas is continuously introduced into the environmental replacement chamber to cool the gallium nitride, resulting in a gallium nitride material with a smooth surface. After the gallium nitride material has been cooled, the remaining gas in the environmental replacement chamber is first extracted, the vacuum breaking valve 16 is opened to introduce air into the environmental replacement chamber 11, and finally the gallium nitride material is removed.

[0058] In some embodiments, during step S30, i.e., the polishing process, the voltage stabilizing unit is activated to ensure stable gas pressure in the environmental displacement chamber during gallium nitride polishing. Furthermore, the voltage stabilizing unit is equipped with a pressure feedback control system that measures the pressure within the environmental displacement chamber using a vacuum gauge and adjusts the pumping rate of the pressure-stabilizing pump in real time to ensure stable pressure within the chamber.

[0059] In some embodiments, when performing step S30, the gallium nitride material is located on a voltage-stabilized vacuum base and covered by a voltage-stabilized vacuum guide hood. The synergistic effect of negative pressure suction and hot airflow can be used to directionally guide and quickly extract the high-temperature reaction products, preventing them from being deposited secondary on the gallium nitride surface.

[0060] The following examples further illustrate the present invention in detail. It should also be understood that the following examples are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention.

[0061] Example 1 This embodiment demonstrates the surface roughness improvement effect of the polishing method (also known as the environmental displacement plasma etching method) proposed in this invention on gallium nitride (GaN) surface. It not only solves the high-temperature oxidation problem in GaN polishing, but also solves the problem of unstable etching rate and surface microparticle contamination caused by the accumulation of reaction products in the sealed cavity through the unique "voltage stabilization + local venting" design, laying the hardware foundation for the stable preparation of atomically smooth surfaces.

[0062] This embodiment utilizes the polishing system for gallium nitride (GaN) materials to polish the polar surface of gallium nitride (GaN). The specific process and effects are as follows: In this embodiment, under a nitrogen protective atmosphere, a radio frequency power of 900 W was used, with Ar as the cooling gas and carrier gas, and CF4 as the reactant gas (specific flow rates of 18 slm, 1.5 slm and 60 sccm, respectively). The sample was etched for 3 minutes at a working distance of 15 mm and then cooled with argon for 5 minutes.

[0063] The surfaces of gallium nitride materials before and after polishing were characterized using atomic force microscopy (AFM). The AFM characterization results are as follows: Figure 4 As shown; by Figure 4 It can be seen that the surface roughness Sa value of GaN sample 1 decreased from 98.5 nm to 1.43 nm, and the surface roughness Sa value of GaN sample 2 decreased from 15.1 nm to 0.736 nm, indicating a significant improvement in surface quality.

[0064] In summary, this invention provides a polishing system and method for gallium nitride (GaN) materials. The polishing system includes an environmental displacement device and a plasma generator. The environmental displacement device includes an environmental displacement chamber, a vacuum pump unit for evacuating the environmental displacement chamber, a gas delivery unit for supplying inert gas to the environmental displacement chamber, and a pressure stabilizing unit for maintaining the pressure of the environmental displacement chamber. The plasma generator includes an inductively coupled plasma (ICP) generator disposed within the environmental displacement chamber and a gas supply unit for supplying working gas to the ICP generator. This invention uses the vacuum pump unit to evacuate the air in the environmental displacement chamber, and then uses the gas delivery unit to fill the environmental displacement chamber with inert protective gas, ensuring an oxygen-free environment. Then, within the inert protective gas atmosphere of the environmental displacement chamber, the ICP generator generates plasma to polish the GaN surface. After polishing, the surface is cooled within the environmental displacement chamber, thereby preventing the GaN from being oxidized during the high-temperature reaction process and during cooling, which would otherwise lead to surface roughness deterioration. Meanwhile, the pressure stabilizing unit can maintain a stable pressure within the environmental displacement chamber during the polishing process, and the pressure can be adjusted in real time.

[0065] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A polishing system for gallium nitride materials, characterized in that, Includes an environmental replacement device and a plasma generator; The environmental replacement device includes an environmental replacement chamber, a vacuum pump unit for evacuating the environmental replacement chamber, a gas delivery unit for delivering inert gas to the environmental replacement chamber, and a pressure stabilizing unit for maintaining the pressure of the environmental replacement chamber. The plasma generating device includes an inductively coupled plasma generating unit disposed within the environmental displacement chamber and a gas supply unit for providing working gas to the inductively coupled plasma generating unit.

2. The polishing system for gallium nitride materials according to claim 1, characterized in that, The environmental replacement device also includes a vacuum gauge located outside the environmental replacement chamber for feedback on the vacuum level inside the environmental replacement chamber; the environmental replacement chamber is equipped with a door, and the door is equipped with an observation window.

3. The polishing system for gallium nitride materials according to claim 1, characterized in that, The vacuum pump unit includes a vacuum pump and a vacuum extraction pipe for connecting the vacuum pump to the environmental replacement chamber; the gas delivery unit includes an inert gas storage tank and an inert gas delivery pipe for connecting the inert gas storage tank to the environmental replacement chamber, and a control valve is provided at the connection between the inert gas storage tank and the inert gas delivery pipe.

4. The polishing system for gallium nitride materials according to claim 1, characterized in that, The inductively coupled plasma generating unit includes a radio frequency power supply, a matching device electrically connected to the radio frequency power supply, an induction coil electrically connected to the matching device, a torch tube disposed within the induction coil, and an electric spark generator for generating an electric spark within the torch tube.

5. The polishing system for gallium nitride materials according to claim 4, characterized in that, The torch tube includes a torch tube mounting head disposed on the inner wall of the environmental replacement chamber, an inner torch tube and an outer torch tube coaxially mounted on the torch tube mounting head; the induction coil is disposed around the outer side of the outer torch tube.

6. The polishing system for gallium nitride materials according to claim 4, characterized in that, The polishing system for gallium nitride materials also includes a three-axis motion platform disposed below the torch tube; The pressure stabilizing unit is located on the side of the three-axis motion platform near the torch tube; the pressure stabilizing unit includes a pressure stabilizing and suction base, a pressure feedback control system, and a pressure stabilizing and suction guide hood that matches the pressure stabilizing and suction base and is coaxially arranged on the end of the torch tube near the three-axis motion platform.

7. The polishing system for gallium nitride materials according to claim 4, characterized in that, The polishing system for gallium nitride materials further includes a cooling device; the cooling device includes a chiller and a cooling water pipe connected to the chiller; the cooling water pipe is arranged along the radio frequency power supply, the matching unit, the environmental displacement cavity, the induction coil and the torch tube.

8. The polishing system for gallium nitride materials according to claim 1, characterized in that, The gas supply unit includes a cooling gas storage tank, a reaction gas storage tank, and a carrier gas storage tank; the cooling gas storage tank, the reaction gas storage tank, and the carrier gas storage tank are respectively connected to the inductively coupled plasma generating unit through pipelines.

9. A polishing method for gallium nitride material, characterized in that, Including the following steps: Gallium nitride material is placed in an environmental replacement chamber, the environmental replacement chamber is evacuated, and then an inert gas is injected into the environmental replacement chamber. Provide cooling gas for the inductively coupled plasma generation unit; After providing the reactive gas and carrier gas to the inductively coupled plasma generating unit, and turning on the radio frequency power supply, matching unit and electric spark generator, the inductively coupled plasma generating unit excites plasma to polish the gallium nitride material.

10. The polishing method for gallium nitride material according to claim 9, characterized in that, The cooling gas is argon; the reaction gas is carbon tetrafluoride; the carrier gas is argon; and the inert gas is nitrogen.

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