A constant temperature platform surface flat processing technology

Abstract

The application discloses a constant-temperature platform surface flat processing technology, which is suitable for semiconductor carrier processing. The steps include substrate pretreatment, precision milling forming, composite coating preparation, flat-top laser-assisted precision polishing and constant-temperature curing. The substrate pretreatment removes stress and performs roughening cleaning; the precision milling ensures initial flatness; the composite coating sequentially prepares a nickel-phosphorus chemical plating bottom layer, a TiN transition layer and a DLC functional top layer; the flat-top laser precision polishing improves surface precision; and the constant-temperature curing eliminates internal stress. The application aims to overcome the defects of the prior art, such as insufficient precision, poor plating layer adhesion and low product qualification rate, by optimizing process steps, precisely controlling parameters, improving plating layer structure and solution formula, realizing high-precision flat processing of the semiconductor carrier surface, improving product performance and qualification rate, and meeting the harsh requirements of semiconductor chip processing.

Description

Technical Field

[0001] This invention relates to the field of semiconductor processing equipment manufacturing technology, specifically to a constant temperature platform surface flattening process. Background Technology

[0002] The temperature-controlled platform (semiconductor stage) is a core auxiliary component in the semiconductor chip fabrication process. Its main function is to provide stable and uniform temperature support for the chips. The surface flatness of the platform directly affects the chip processing accuracy, heating uniformity, and product yield. Semiconductor chip fabrication places extremely high demands on the surface flatness of the metal platform, typically requiring a flatness of ≤0.005 mm / cm. 2 The surface roughness Ra≤0.1μm is required, and the stage surface must have good wear resistance, corrosion resistance and coating adhesion to adapt to long-term high temperature and high precision processing environment.

[0003] In existing technologies, the surface planarization process for semiconductor stages mostly adopts the traditional process of "rough machining - fine grinding - polishing", which has the following technical defects: Firstly, traditional polishing often uses Gaussian laser polishing or mechanical polishing. Gaussian laser polishing has uneven energy distribution, which can easily lead to damage to the coating on the stage surface and fluctuations in flatness. Mechanical polishing, on the other hand, is difficult to achieve the high precision required for semiconductor processing and is prone to scratches. Secondly, some processes use a single or double coating structure, resulting in poor coating adhesion. Over long-term use, this can lead to peeling and detachment, affecting the service life of the platform. Third, during the substrate pretreatment process, the formulation and preparation method of the alkaline washing solution and plating solution are unreasonable, resulting in incomplete removal of oil stains and impurities on the substrate surface, uneven coating deposition, and further affecting the surface flatness accuracy. Fourth, the poor coordination of parameters in each process step and the lack of precise control make it difficult for the flatness, roughness and coating adhesion of the final product to consistently meet the stringent requirements of semiconductor processing, resulting in a low product qualification rate.

[0004] Therefore, in order to solve the above problems, this technical solution proposes a constant temperature platform surface flattening process that is reasonable in process, accurate in parameters, and fully disclosed, which can effectively solve the above technical defects, significantly improve the surface flatness accuracy, coating adhesion and service life of semiconductor stage, and is significantly different from the existing technology. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing semiconductor stage surface flattening processes, such as insufficient precision, poor coating adhesion, and low product yield. This invention provides a constant temperature platform surface flattening process that optimizes process steps, precisely controls parameters, improves coating structure and solution formulation, achieves high-precision surface flattening of semiconductor stage, improves product performance and yield, and meets the stringent requirements of semiconductor chip processing.

[0006] To achieve the above objectives, the present invention provides the following technical solution: The technical solution provided by this invention includes the following steps: S1. Substrate Pretreatment: Select semiconductor-specific metal substrates and sequentially perform stress-relief annealing, surface roughening, and ultra-clean cleaning. The stress-relief annealing involves holding at 500-700℃ for 2-4 hours and then slowly cooling to room temperature at a rate of 50-80℃ / h. The surface roughening is performed by sandblasting with corundum abrasive particles of 80-120 mesh, a sandblasting pressure of 0.3-0.5MPa, and a sandblasting time of 10-15 minutes. The ultra-clean cleaning involves sequentially performing ultrasonic solvent degreasing, alkaline degreasing, DI water rinsing, and nitrogen drying. The alkaline degreasing solution is composed of the following raw materials in parts by weight: sodium hydroxide 10-15 parts, sodium carbonate 8-12 parts, sodium silicate 5-8 parts, surfactant 2-4 parts, and deionized water 60-75 parts. S2. Precision Milling: Pre-treated metal substrates are CNC milled using carbide micro-diameter end mills. A vacuum chuck and adjustable support column combination clamping system is used. The milling speed is controlled at 8000-12000 r / min, the feed rate at 0.1-0.3 mm / r, and the depth of cut at 0.5-1.5 mm. After milling, a CAM system dynamically corrects tool wear errors to ensure the initial surface flatness of the substrate is ≤0.02 mm / cm. 2 ; S3. Composite Coating Preparation: A nickel-phosphorus electroless plating underlayer, a TiN transition layer, and a DLC functional top layer are sequentially prepared on the milled substrate surface. The nickel-phosphorus electroless plating underlayer consists of the following raw materials by weight: 25-35 parts nickel sulfate, 20-30 parts sodium hypophosphite, 8-12 parts sodium citrate, 4-6 parts sodium acetate, 1-2 parts brightener, and 100-120 parts deionized water. The plating temperature is 85-95℃, the plating time is 60-90 min, and the coating thickness is 10-15 μm. The TiN transition layer uses… The coating is prepared by magnetron sputtering with a sputtering power of 150-200W, a sputtering gas pressure of 0.1-0.3Pa, a deposition temperature of 400-500℃, a deposition time of 30-45min, and a coating thickness of 3-5μm. The functional top layer of the DLC is prepared by plasma-enhanced chemical vapor deposition with a reaction gas of a mixture of methane and argon (volume ratio 1:8-12), a reaction gas pressure of 0.5-1.0Pa, a deposition temperature of 200-300℃, a deposition time of 45-60min, and a coating thickness of 2-4μm. S4. Flat-top laser-assisted fine polishing: The Gaussian laser is modulated into a flat-top laser to perform fine polishing on the surface of the composite coating. The spot diameter is 200-500μm, the laser power is 8-12W, the polishing speed is 1500-2000r / min, and the polishing time is 20-30min. Argon gas protection is used during the polishing process to control the surface temperature fluctuation ≤±0.1℃. S5. Constant Temperature Curing and Testing: The polished metal stage is cured at 120-150℃ for 2-3 hours, cooled to room temperature, and then tested. The final surface flatness is ≤0.005mm / cm. 2 A thermostatic metal stage for semiconductors with a surface roughness Ra≤0.1μm and a coating adhesion strength>50MPa.

[0007] Furthermore, the semiconductor-specific metal substrate mentioned in step S1 is one of 6061-T6 aluminum alloy, Kovar alloy, or titanium alloy, and the substrate thickness is 5-10mm.

[0008] Furthermore, the surfactant mentioned in step S1 is a fatty alcohol polyoxyethylene ether, and the brightener is a compound of sodium saccharin and polyethylene glycol, with a weight ratio of 1:1.5-2.5.

[0009] Furthermore, in step S3, the pH value of the plating solution for the nickel-phosphorus electroless plating underlayer is 4.5-5.5, the density of the TiN transition layer is ≥98%, and the hardness of the DLC functional top layer is HV2500-3000.

[0010] Furthermore, in step S4, the pulse width of the flat-top laser is 10-20 ns, and the repetition frequency is 100-200 kHz.

[0011] Furthermore, in step S5, the heating rate of the constant temperature curing oven is 30-50℃ / h, and the cooling process adopts natural cooling. The qualified inspection standard is: surface flatness ≤ 0.005mm / cm. 2 Surface roughness Ra≤0.1μm, coating adhesion>50MPa, defective products need to be returned to step S4 for re-polishing.

[0012] Furthermore, in step S1, the ultrasonic solvent degreasing uses ethanol as the solvent, the degreasing temperature is 40-50℃, and the degreasing time is 15-20 min.

[0013] Furthermore, the plasma power of the plasma-enhanced chemical vapor deposition method described in step S3 is 80-120W.

[0014] Further, the alkaline washing solution in step S1 is prepared as follows: Weigh 10-15 parts of sodium hydroxide, 8-12 parts of sodium carbonate, 5-8 parts of sodium silicate, 2-4 parts of surfactant, and 60-75 parts of deionized water by weight. First, heat the deionized water to 40-50°C, then add sodium hydroxide, sodium carbonate, and sodium silicate in sequence, and stir until completely dissolved. After cooling to room temperature, add the surfactant and continue stirring for 15-20 minutes until the solution is uniform and free of precipitate, thus obtaining the alkaline washing solution.

[0015] Further, the preparation method of the nickel-phosphorus electroless plating underlayer in step S3 is as follows: Weigh 25-35 parts by weight of nickel sulfate, 20-30 parts by weight of sodium hypophosphite, 8-12 parts by weight of sodium citrate, 4-6 parts by weight of sodium acetate, 1-2 parts by weight of brightener, and 100-120 parts by weight of deionized water. Place the deionized water in a container at room temperature, add sodium citrate and sodium acetate in sequence, and stir until completely dissolved. Then add nickel sulfate and stir until dissolved. Add sodium hypophosphite and continue stirring for 30-40 minutes. Finally, add brightener and stir for 10-15 minutes. Adjust the pH value of the plating solution to 4.5-5.5 to obtain the nickel-phosphorus electroless plating underlayer.

[0016] The beneficial effects of this technical solution are: (1) This invention adopts an integrated process of substrate pretreatment, precision milling, composite coating, flat-top laser polishing, and constant temperature curing. The parameters of each step are matched in coordination, and each processing link is precisely controlled, which effectively solves the problems of insufficient precision and chaotic parameters in existing processes. The surface flatness of the final product is ≤0.005mm / cm. 2 With a surface roughness Ra≤0.1μm and a coating adhesion >50MPa, it fully meets the stringent requirements of semiconductor chip processing.

[0017] (2) The present invention adopts a three-layer composite coating structure of nickel-phosphorus electroless plating bottom layer, TiN transition layer and DLC functional top layer. Compared with the existing single coating or double coating, the TiN transition layer can effectively alleviate the difference in thermal expansion coefficient between the bottom layer and the top layer, and avoid coating peeling and falling off. The nickel-phosphorus electroless plating bottom layer improves the hardness and corrosion resistance of the substrate, and the DLC functional top layer improves the surface wear resistance and smoothness. The three work together to significantly improve the service life and stability of the stage.

[0018] (3) The present invention optimizes the formulation and preparation method of alkaline washing solution and nickel-phosphorus chemical plating bottom layer solution. By using a specific weight ratio of raw materials, the alkaline washing solution can thoroughly remove oil stains, oxide layer and impurities on the substrate surface without residue or damage to the substrate, laying a good foundation for subsequent flattening processing.

[0019] (4) The present invention adopts a flat-top laser-assisted fine polishing process, which is different from the existing Gaussian laser polishing. The Gaussian laser is modulated into a flat-top laser with uniform energy distribution. With argon gas protection and real-time temperature monitoring, the coating surface can be made highly precise and flat, avoiding coating oxidation, thermal deformation and damage. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the process flow for a constant temperature platform surface smoothing process proposed in this invention. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] The specific implementation process is as follows: In the following examples and comparative examples, all raw materials used were commercially available conventional products, including: the surfactant was fatty alcohol polyoxyethylene ether (model AEO-9), the brightener was a compound of sodium saccharin and polyethylene glycol (molecular weight 400), the semiconductor-specific metal substrates were 6061-T6 aluminum alloy, Kovar alloy, and titanium alloy, respectively, the corundum abrasive was commercially available 80-120 mesh white corundum, the argon gas purity was ≥99.99%, and the DI water was deionized water (conductivity ≤10μS / cm).

[0023] Example 1:

[0024] Please see Figure 1The present invention provides a technical solution: a surface flattening process for a constant temperature platform, wherein the constant temperature platform is a metal stage for semiconductors (the substrate is 6061-T6 aluminum alloy, with a thickness of 8mm), and the specific steps are as follows: S1. Substrate pretreatment: 1. Stress-relief annealing: Place the 6061-T6 aluminum alloy substrate in an annealing furnace, heat it to 500℃, hold it for 4 hours, and then slowly cool it to room temperature at a rate of 50℃ / h. 2. Surface roughening: Sandblasting is used, with corundum abrasive particles of 80 mesh, sandblasting pressure of 0.3 MPa, and sandblasting time of 15 min. 3. Ultra-clean cleaning: The process involves ultrasonic solvent degreasing, alkaline degreasing, DI water rinsing, and nitrogen drying. Ultrasonic solvent degreasing uses ethanol as the solvent at 40℃ for 20 minutes. The alkaline degreasing solution is prepared as follows: Weigh 10 kg of sodium hydroxide, 8 kg of sodium carbonate, 5 kg of sodium silicate, 2 kg of surfactant, and 60 kg of deionized water according to weight. First, heat the deionized water to 40℃, then add sodium hydroxide, sodium carbonate, and sodium silicate sequentially, stirring until completely dissolved. After cooling to room temperature, add the surfactant and continue stirring for 15 minutes until the solution is homogeneous and free of precipitate, obtaining the alkaline degreasing solution. The alkaline degreasing time is 15 minutes, followed by DI water rinsing three times (5 minutes each time), and nitrogen drying (flow rate 10 L / min). S2. Precision Milling: A carbide micro-diameter end mill (0.8mm diameter) is used to CNC mill the pre-treated metal substrate. A vacuum chuck and adjustable support column combination is used for clamping. The milling speed is controlled at 8000 r / min, the feed rate at 0.1 mm / r, and the depth of cut at 0.5 mm. After milling, a CAM system is used to dynamically correct tool wear errors. The initial surface flatness of the substrate is measured to be 0.018 mm / cm. 2 ; S3. Preparation of composite coating: 1. Nickel-phosphorus electroless plating underlayer: The plating solution consists of the following raw materials by weight: 25 kg nickel sulfate, 20 kg sodium hypophosphite, 8 kg sodium citrate, 4 kg sodium acetate, 1 kg brightener (sodium saccharin to polyethylene glycol weight ratio 1:1.5), and 100 kg deionized water. The plating solution is prepared as follows: Place deionized water in a container at room temperature, add sodium citrate and sodium acetate sequentially, and stir until completely dissolved. Then add nickel sulfate and stir until dissolved. Add sodium hypophosphite and continue stirring for 30 minutes. Finally, add brightener and stir for 10 minutes. Adjust the pH of the plating solution to 4.5 to obtain the plating solution. Place the milled substrate into the plating solution, plate at 85℃ for 90 minutes, and obtain a 10 μm thick nickel-phosphorus electroless plating underlayer (phosphorus content 8 wt%). 2. TiN transition layer: prepared by magnetron sputtering with a sputtering power of 150W, a sputtering gas pressure of 0.1Pa, a deposition temperature of 400℃, and a deposition time of 45min, resulting in a TiN transition layer with a thickness of 3μm (density 98%, hardness HV1800). 3. DLC functional top layer: prepared by plasma-enhanced chemical vapor deposition, plasma power 80W, reaction gas is a mixture of methane and argon (volume ratio 1:8), reaction pressure 0.5Pa, deposition temperature 200℃, deposition time 60min, to obtain a DLC functional top layer with a thickness of 2μm (friction coefficient 0.08, hardness HV2500). S4. Flat-top laser-assisted fine polishing: Gaussian laser is modulated into a flat-top laser by a combination of a beam expander, a shaping mirror (diffractive optical element), and a focusing mirror. The pulse width is 10ns, the repetition frequency is 100kHz, and the composite coating surface is finely polished. The spot diameter is 200μm, the laser power is 8W, the polishing speed is 1500r / min, and the polishing time is 30min. Argon gas protection (flow rate 5L / min) is used during the polishing process, and the surface temperature is monitored in real time to control the temperature fluctuation ≤±0.1℃. S5. Constant Temperature Curing and Testing: Place the polished metal stage into a constant temperature curing oven, heat it to 120℃ at a heating rate of 30℃ / h, and cure it at a constant temperature for 3 hours. Then let it cool naturally to room temperature. After cooling, conduct comprehensive testing and record all performance indicators.

[0025] As shown in the experimental data table above, the initial flatness of the semiconductor isothermal metal stage substrate prepared in Example 1 after milling is 0.018 mm / cm. 2 It meets the requirement of ≤0.02mm / cm 2 The requirements laid a solid foundation for the subsequent composite coating preparation and fine polishing process; the final surface flatness was 0.004 mm / cm. 2 The surface roughness Ra is 0.08 μm, which is better than the ≤0.005 mm / cm specified in the claims. 2 The coating thickness is ≤0.1μm; the coating adhesion is 52MPa, which is greater than the requirement of 50MPa, indicating that the composite coating is tightly bonded to the substrate and is not easy to peel off.

[0026] Example 2:

[0027] Please see Figure 1 The present invention provides a technical solution: a surface flattening process for a constant temperature platform, wherein the constant temperature platform is a metal stage for semiconductors (the substrate is Kovar alloy, with a thickness of 8mm), and the specific steps are as follows: S1. Substrate pretreatment: 1. Stress-relief annealing: Place the Kovar alloy substrate in an annealing furnace, heat it to 600℃, hold it for 3 hours, and then slowly cool it to room temperature at a rate of 65℃ / h. 2. Surface roughening: Sandblasting is used, with corundum abrasive particles of 100 mesh, sandblasting pressure of 0.4 MPa, and sandblasting time of 12 min. 3. Ultra-clean cleaning: The process involves ultrasonic solvent degreasing, alkaline degreasing, DI water rinsing, and nitrogen drying. Ultrasonic solvent degreasing uses ethanol as the solvent at 45℃ for 18 minutes. The alkaline degreasing solution is prepared as follows: Weigh 12 kg of sodium hydroxide, 10 kg of sodium carbonate, 6.5 kg of sodium silicate, 3 kg of surfactant, and 68 kg of deionized water. First, heat the deionized water to 45℃, then add sodium hydroxide, sodium carbonate, and sodium silicate sequentially, stirring until completely dissolved. After cooling to room temperature, add the surfactant and continue stirring for 18 minutes until the solution is homogeneous and free of precipitate, obtaining the alkaline degreasing solution. The alkaline degreasing time is 12 minutes, followed by DI water rinsing three times (5 minutes each time), and nitrogen drying (flow rate 10 L / min). S2. Precision Milling: A carbide micro-diameter end mill (0.8mm diameter) is used to CNC mill the pre-treated metal substrate. A vacuum chuck and adjustable support column combination is used for clamping. The milling speed is controlled at 10000 r / min, the feed rate is 0.2 mm / r, and the depth of cut is 1.0 mm. After milling, a CAM system is used to dynamically correct tool wear errors. The initial surface flatness of the substrate is measured to be 0.015 mm / cm. 2 ; S3. Preparation of composite coating: 1. Nickel-phosphorus electroless plating underlayer: The plating solution consists of the following raw materials by weight: 30 kg nickel sulfate, 25 kg sodium hypophosphite, 10 kg sodium citrate, 5 kg sodium acetate, 1.5 kg brightener (sodium saccharin to polyethylene glycol weight ratio 1:2.0), and 110 kg deionized water. The plating solution is prepared as follows: Place deionized water in a container at room temperature, add sodium citrate and sodium acetate sequentially, and stir until completely dissolved. Then add nickel sulfate and stir until dissolved. Add sodium hypophosphite and continue stirring for 35 minutes. Finally, add brightener and stir for 12 minutes. Adjust the pH of the plating solution to 5.0 to obtain the plating solution. Place the milled substrate into the plating solution, plate at 90℃ for 75 minutes, and obtain a nickel-phosphorus electroless plating underlayer with a thickness of 12 μm (phosphorus content 10 wt%). 2. TiN transition layer: prepared by magnetron sputtering with a sputtering power of 175W, a sputtering gas pressure of 0.2Pa, a deposition temperature of 450℃, and a deposition time of 38min, resulting in a TiN transition layer with a thickness of 4μm (density 98.5%, hardness HV2000). 3. DLC functional top layer: prepared by plasma-enhanced chemical vapor deposition, plasma power 100W, reaction gas is a mixture of methane and argon (volume ratio 1:10), reaction pressure 0.75Pa, deposition temperature 250℃, deposition time 52min, to obtain a DLC functional top layer with a thickness of 3μm (friction coefficient 0.07, hardness HV2800). S4. Flat-top laser-assisted fine polishing: A Gaussian laser is modulated into a flat-top laser by a combination of a beam expander, a shaping mirror (diffractive optical element), and a focusing mirror. The pulse width is 15ns, the repetition frequency is 150kHz, and the composite coating surface is finely polished. The spot diameter is 350μm, the laser power is 10W, the polishing speed is 1750r / min, and the polishing time is 25min. Argon gas protection (flow rate 6.5L / min) is used during the polishing process, and the surface temperature is monitored in real time to control the temperature fluctuation ≤±0.1℃. S5. Constant Temperature Curing and Testing: Place the polished metal stage into a constant temperature curing oven, heat it to 135℃ at a heating rate of 40℃ / h, and cure it at a constant temperature for 2.5h. Then let it cool naturally to room temperature. After cooling, conduct comprehensive testing and record all performance indicators.

[0028] Example 2 uses Kovar alloy as the substrate, and the process parameters are the median values ​​within the scope of the claims. All performance indicators are superior to those of Example 1, and the initial flatness of the substrate after milling is 0.015 mm / cm. 2 This is superior to Example 1, indicating that optimizing the precision milling parameters can further improve the initial flatness accuracy of the substrate; the final surface flatness is 0.003 mm / cm. 2 Surface roughness Ra 0.07μm.

[0029] Example 3:

[0030] Please see Figure 1 The present invention provides a technical solution: a surface flattening process for a constant temperature platform, wherein the constant temperature platform is a metal stage for semiconductors (the substrate is a titanium alloy with a thickness of 8mm), and the specific steps are as follows: S1. Substrate pretreatment: 1. Stress-relief annealing: Place the titanium alloy substrate in an annealing furnace, heat it to 700℃, hold it for 2 hours, and then slowly cool it to room temperature at a rate of 80℃ / h. 2. Surface roughening: Sandblasting is used, with corundum abrasive particles of 120 mesh, sandblasting pressure of 0.5 MPa, and sandblasting time of 10 min. 3. Ultra-clean cleaning: The process involves ultrasonic solvent degreasing, alkaline degreasing, DI water rinsing, and nitrogen drying. Ultrasonic solvent degreasing uses ethanol as the solvent at 50℃ for 15 minutes. The alkaline degreasing solution is prepared as follows: Weigh 15 kg of sodium hydroxide, 12 kg of sodium carbonate, 8 kg of sodium silicate, 4 kg of surfactant, and 75 kg of deionized water. First, heat the deionized water to 50℃, then add sodium hydroxide, sodium carbonate, and sodium silicate sequentially, stirring until completely dissolved. After cooling to room temperature, add the surfactant and continue stirring for 20 minutes until the solution is homogeneous and free of precipitate, obtaining the alkaline degreasing solution. The alkaline degreasing time is 10 minutes, followed by DI water rinsing three times (5 minutes each time), and nitrogen drying (flow rate 10 L / min). S2. Precision Milling: A carbide micro-diameter end mill (0.8mm diameter) is used to CNC mill the pre-treated metal substrate. A vacuum chuck and adjustable support column combination is used for clamping. The milling speed is controlled at 12000 r / min, the feed rate at 0.3 mm / r, and the depth of cut at 1.5 mm. After milling, a CAM system is used to dynamically correct tool wear errors. The initial surface flatness of the substrate is measured to be 0.012 mm / cm. 2 ; S3. Preparation of composite coating: 1. Nickel-phosphorus electroless plating underlayer: The plating solution consists of the following raw materials by weight: 35 kg nickel sulfate, 30 kg sodium hypophosphite, 12 kg sodium citrate, 6 kg sodium acetate, 2 kg brightener (sodium saccharin to polyethylene glycol weight ratio 1:2.5), and 120 kg deionized water. The plating solution is prepared as follows: Place deionized water in a container at room temperature, add sodium citrate and sodium acetate sequentially, and stir until completely dissolved. Then add nickel sulfate and stir until dissolved. Add sodium hypophosphite and continue stirring for 40 minutes. Finally, add brightener and stir for 15 minutes. Adjust the pH of the plating solution to 5.5 to obtain the plating solution. Place the milled substrate into the plating solution, plate at 95℃ for 60 minutes to obtain a nickel-phosphorus electroless plating underlayer with a thickness of 15 μm (phosphorus content 12 wt%). 2. TiN transition layer: prepared by magnetron sputtering with a sputtering power of 200W, a sputtering gas pressure of 0.3Pa, a deposition temperature of 500℃, and a deposition time of 30min, resulting in a TiN transition layer with a thickness of 5μm (density 99%, hardness HV2200). 3. DLC functional top layer: prepared by plasma-enhanced chemical vapor deposition, plasma power 120W, reaction gas is a mixture of methane and argon (volume ratio 1:12), reaction pressure 1.0Pa, deposition temperature 300℃, deposition time 45min, to obtain a DLC functional top layer with a thickness of 4μm (friction coefficient 0.06, hardness HV3000). S4. Flat-top laser-assisted fine polishing: A Gaussian laser is modulated into a flat-top laser by a combination of a beam expander, a shaping mirror (diffractive optical element), and a focusing mirror. The pulse width is 20ns, the repetition frequency is 200kHz, and the composite coating surface is finely polished. The spot diameter is 500μm, the laser power is 12W, the polishing speed is 2000r / min, and the polishing time is 20min. Argon gas protection (flow rate 8L / min) is used during the polishing process, and the surface temperature is monitored in real time to control the temperature fluctuation ≤±0.1℃. S5. Constant Temperature Curing and Testing: Place the polished metal stage into a constant temperature curing oven, heat it to 150℃ at a heating rate of 50℃ / h, and cure it at a constant temperature for 2 hours. Then let it cool naturally to room temperature. After cooling, conduct comprehensive testing and record all performance indicators.

[0031] Example 3 uses titanium alloy as the substrate, and all performance indicators reach the optimal level of this invention and fully comply with the standards defined in the claims. The initial flatness of the substrate after milling is 0.012 mm / cm. 2 This is the optimal configuration among the three embodiments, benefiting from a higher milling speed and finer sandblasting, which provides a good foundation for subsequent fine polishing processes; the final surface flatness is only 0.002 mm / cm. 2 The surface roughness Ra is 0.06 μm.

[0032] Example 4:

[0033] Please see Figure 1 The present invention provides a technical solution: a process for surface smoothing of a constant temperature platform. A surface smoothing process for a constant temperature platform differs from that in Example 1 in that: 1. Base material: 6061-T6 aluminum alloy, 5mm thick; 2. Substrate pretreatment: 1. Stress-relief annealing: Heat to 550℃, hold for 3.5 hours, and then slowly cool to room temperature at a rate of 55℃ / h; 2. Surface roughening: Corundum abrasive particle size 90 mesh, sandblasting pressure 0.35MPa, sandblasting time 14min; 3. Ultra-clean cleaning: Ultrasonic degreasing temperature 42℃, time 19min; Alkaline cleaning solution formula: sodium hydroxide 11kg, sodium carbonate 9kg, sodium silicate 6kg, surfactant 2.5kg, deionized water 65kg; Deionized water is heated to 42℃ and stirred for 16min during alkaline cleaning solution preparation; Alkaline cleaning degreasing time is 14min. 3. Precision milling forming: milling speed 9000 r / min, feed rate 0.15 mm / r, milling depth 0.8 mm; initial surface flatness of the substrate after milling 0.017 mm / cm.2 ; 4. Preparation of composite coating: 1. Nickel-phosphorus electroless plating underlayer: Plating solution formula: 28 kg nickel sulfate, 22 kg sodium hypophosphite, 9 kg sodium citrate, 4.5 kg sodium acetate, 1.2 kg brightener (sodium saccharin to polyethylene glycol weight ratio 1:1.8), 105 kg deionized water; stirring time during plating solution preparation: 32 min, 11 min; pH value of plating solution: 4.8; plating temperature: 88℃, time: 85 min; plating thickness: 11 μm; phosphorus content: 9 wt%. 2. TiN transition layer: sputtering power 160W, sputtering pressure 0.15Pa, deposition temperature 420℃, deposition time 42min, coating thickness 3.5μm, density 98.2%, hardness HV1900; 3. DLC functional top layer: plasma power 90W, reaction gas volume ratio 1:9, reaction gas pressure 0.6Pa, deposition temperature 220℃, deposition time 55min, coating thickness 2.5μm, friction coefficient 0.075, hardness HV2600; 5. Flat-top laser-assisted fine polishing: pulse width 12ns, repetition frequency 120kHz, spot diameter 250μm, laser power 9W, polishing speed 1600r / min, polishing time 28min, argon flow rate 5.5L / min; 6. Constant temperature curing and testing: heating rate 35℃ / h, constant temperature 125℃, constant temperature time 2.8h; Example 4 uses a 5mm thick 6061-T6 aluminum alloy substrate. The process parameters are slightly adjusted based on Example 1, and the overall performance is better than Example 1, but slightly worse than Examples 2 and 3. The initial flatness of the substrate after milling is 0.017mm / cm. 2 Slightly superior to Example 1, thanks to fine-tuning of milling speed and feed rate, the initial flatness accuracy of the substrate was improved; the final surface flatness was 0.0035 mm / cm. 2 The surface roughness Ra is 0.075μm, indicating that fine-tuning of process parameters will not affect the core performance of the product.

[0034] Example 5:

[0035] Please see Figure 1 The present invention provides a technical solution: a constant temperature platform surface smoothing process, which differs from Example 1 in that: 1. Substrate: Kovar alloy, 10mm thick; 2. Substrate pretreatment: 1. Stress-relief annealing: Heat to 650℃, hold for 2.5h, and then slowly cool to room temperature at a rate of 75℃ / h; 2. Surface roughening: Corundum abrasive particle size 110 mesh, sandblasting pressure 0.45MPa, sandblasting time 11min; 3. Ultra-clean cleaning: Ultrasonic degreasing temperature 48℃, time 16min; Alkaline cleaning solution formula: sodium hydroxide 14kg, sodium carbonate 11kg, sodium silicate 7.5kg, surfactant 3.5kg, deionized water 72kg; Deionized water is heated to 48℃ and stirred for 19min during alkaline cleaning solution preparation; Alkaline cleaning degreasing time 11min; 3. Precision milling: Milling speed 11000 r / min, feed rate 0.25 mm / r, milling depth 1.2 mm; initial surface flatness of the substrate after milling 0.013 mm / cm. 2 ; 4. Preparation of composite coating: 1. Nickel-phosphorus electroless plating underlayer: Plating solution formula: 32 kg nickel sulfate, 28 kg sodium hypophosphite, 11 kg sodium citrate, 5.5 kg sodium acetate, 1.8 kg brightener (sodium saccharin to polyethylene glycol weight ratio 1:2.2), 115 kg deionized water; stirring times during plating solution preparation were 38 min and 14 min respectively; pH ​​value of plating solution was 5.2; plating temperature was 92℃, time was 68 min, coating thickness was 14 μm, and phosphorus content was 11 wt%. 2. TiN transition layer: sputtering power 190W, sputtering gas pressure 0.25Pa, deposition temperature 480℃, deposition time 33min, coating thickness 4.5μm, density 98.8%, hardness HV2100; 3. DLC functional top layer: plasma power 110W, reactive gas volume ratio 1:11, reactive gas pressure 0.9Pa, deposition temperature 280℃, deposition time 48min, coating thickness 3.5μm, friction coefficient 0.065, hardness HV2900 (Example 1: 80W, 1:8, 0.5Pa, 200℃, 60min, 2μm, 0.08, HV2500); 5. Flat-top laser-assisted fine polishing: pulse width 18ns, repetition frequency 180kHz, spot diameter 450μm, laser power 11W, polishing speed 1900r / min, polishing time 22min, argon flow rate 7.5L / min; 6. Constant temperature curing and testing: Heating rate 45℃ / h, constant temperature 145℃, constant temperature time 2.2h; after cooling, conduct comprehensive testing and record all performance indicators.

[0036] Example 5 used a 10mm thick Kovar alloy substrate. The process parameters were adjusted from those of Example 1 towards the optimal parameters of Example 3. All performance indicators were at an excellent level, and the overall performance was between that of Examples 2 and 3. The initial flatness of the substrate after milling was 0.013mm / cm. 2 This method is superior to Examples 1 and 2, thanks to the higher milling speed, finer sandblasting, and the material advantages of Kovar alloy itself, which provides a high-quality foundation for subsequent composite coating preparation and fine polishing processes.

[0037] Comparative Example 1: Please see Figure 1 The present invention provides a comparative scheme: the difference from Example 1 is that the substrate pretreatment step (no stress relief annealing, surface roughening, and ultra-clean cleaning) is omitted, and the original 6061-T6 aluminum alloy substrate is directly precision milled and shaped and then processed. The remaining process steps and parameters are completely consistent with Example 1.

[0038] Comparative Example 1, due to the lack of a substrate pretreatment step, had a product qualification rate of only 78.0%. The absence of stress-relief annealing resulted in unreleased internal stress in the substrate, leading to an initial flatness of only 0.028 mm / cm after milling. 2 Exceeding ≤0.02mm / cm 2 The requirements were not met; without surface roughening and ultra-clean cleaning, the substrate surface contained oil, impurities, and an oxide layer, resulting in a nickel-phosphorus electroless plating underlayer thickness of only 8μm and a TiN transition layer density of 97.2%, both of which failed to meet the standards. The coating adhesion dropped to 42MPa, far below the requirement of 50MPa. The thickness and hardness of the DLC functional top layer did not meet the specified range, and the surface roughness Ra reached 0.15μm, exceeding the standard of ≤0.1μm. The final surface flatness also failed to meet the requirements, proving that substrate pretreatment is a key step in the process of this invention, directly affecting product performance and yield.

[0039] Comparative Example 2: Please see Figure 1 The present invention provides a comparative scheme: the difference from Example 1 is that the precision milling forming step is omitted, and the composite coating preparation and subsequent processes are carried out directly after the substrate pretreatment. The remaining process steps and parameters are completely consistent with Example 1.

[0040] Comparative Example 2 lacks a precision milling process; the substrate was pretreated and then directly plated, resulting in extremely poor initial flatness of the substrate (0.035 mm / cm). 2 Subsequent laser polishing could not compensate for the initial lack of precision, resulting in a final surface flatness of 0.012 mm / cm. 2The surface roughness Ra was 0.18μm, both failing to meet the standards. Furthermore, the substrate surface was not milled, resulting in uneven surface flatness and uneven coating thickness distribution (9μm for the nickel-phosphorus underlayer and 1.9μm for the DLC top layer). The TiN transition layer density decreased to 97.5%, and the coating adhesion was 45MPa, failing to meet the 50MPa requirement. The product qualification rate was only 72.0%. This demonstrates that precision milling provides a good foundation for subsequent coating preparation and polishing processes, and is crucial for ensuring the final smoothness and coating quality of the product.

[0041] Comparative Example 3: Please see Figure 1 The present invention provides a comparative scheme: the difference from Example 1 is that the TiN transition layer is missing in the preparation of the composite coating, and only the nickel-phosphorus electroless plating bottom layer and the DLC functional top layer are prepared, while the remaining process steps and parameters are completely consistent with Example 1.

[0042] Comparative Example 3 lacks a TiN transition layer, despite having surface smoothness-related indicators (final smoothness 0.0045 mm / cm). 2 The surface roughness (Ra 0.085μm) basically meets the requirements, but the coating adhesion drops to 48MPa, failing to meet the 50MPa limit. The DLC functional top layer has a hardness of 2450HV and a friction coefficient of 0.10, indicating a decline in performance. The product qualification rate is only 89.0%. The core function of the TiN transition layer is to alleviate the difference in thermal expansion coefficients between the nickel-phosphorus underlayer and the DLC top layer and to enhance the bonding stability between coatings. Its absence leads to easy peeling of the DLC top layer and a decrease in wear resistance, proving that the TiN transition layer is a crucial and indispensable layer for ensuring the adhesion and overall performance of the composite coating.

[0043] Comparative Example 4: Please see Figure 1 The present invention provides a comparative scheme: the difference from Example 1 is that ordinary Gaussian laser polishing is used instead of flat-top laser-assisted polishing, and the remaining process steps and parameters are completely consistent with Example 1.

[0044] Comparative Example 4 used a conventional Gaussian laser instead of a flat-top laser for fine polishing. Although the coating adhesion, layer thickness, and hardness generally met the requirements, the final surface flatness was 0.006 mm / cm. 2 The surface roughness Ra is 0.11μm, and the product qualification rate is only 90.0%. Flat-top laser has the advantage of uniform energy distribution, which can avoid the problem of uneven surface polishing caused by excessive energy in the center and insufficient energy at the edge of Gaussian laser. This proves that flat-top laser-assisted polishing is the key process to achieve high-precision flatness of products, and ordinary Gaussian laser cannot replace it.

[0045] Comparative Example 5: Please see Figure 1 The present invention provides a comparative scheme: the difference from Example 1 is that the pH value of the nickel-phosphorus electroless plating underlayer solution is adjusted to 3.8, while the remaining process steps and parameters are completely consistent with Example 1.

[0046] In Comparative Example 5, the pH value of the nickel-phosphorus electroless plating underlayer solution was adjusted to 3.8, leading to abnormalities in various performance indicators related to the plating layer, with a product qualification rate of only 87.0%. The excessively low pH value inhibits the electroless plating reaction rate, resulting in a nickel-phosphorus underlayer thickness of only 8.5 μm, failing to meet the 10-15 μm standard. Simultaneously, the plating density decreased, indirectly causing the TiN transition layer density to drop to 97.8%, failing to meet the ≥98% requirement; the plating adhesion decreased to 49 MPa, failing to meet the >50 MPa standard. Although surface smoothness-related indicators (final smoothness 0.0042 mm / cm) were improved... 2 The surface roughness (Ra 0.09 μm) meets the requirements, but the decline in coating quality will affect the long-term stability of the product. This proves that the pH value of the nickel-phosphorus electroless plating solution within the range specified in the claims is the key to ensuring the coating thickness and adhesion. Deviation will significantly affect the product performance.

[0047] Comparative Example 6: Please see Figure 1 The present invention provides a comparative scheme: the difference from Example 1 is that the sputtering process parameters of the TiN transition layer are adjusted to sputtering power of 120W and argon flow rate of 8L / min, while the remaining process steps and parameters are completely consistent with Example 1.

[0048] In the comparative example, the excessively low sputtering power and excessively high argon flow rate of the TiN transition layer led to a significant decrease in the quality of the TiN transition layer, with a product qualification rate of only 85.0%. Insufficient sputtering power (120W < 150W) resulted in a slower sputtering rate, with the TiN transition layer thickness being only 2.8μm, failing to meet the 3-5μm requirement. Excessively high argon flow rate (8L / min > 6L / min) diluted the target atomic concentration, causing the TiN transition layer density to drop to 97.3%, failing to meet the ≥98% standard. The decreased quality of the TiN transition layer directly affected the bonding stability between coatings, reducing the coating adhesion to 47MPa, failing to meet the >50MPa requirement. Simultaneously, the thickness of the DLC functional top layer also decreased to 1.9μm due to the unevenness of the transition layer, failing to meet the standard. Although surface flatness-related indicators met the requirements, the overall coating quality decreased, proving that the sputtering process parameters of the TiN transition layer must be strictly controlled within the required range to ensure the stability of the composite coating and product performance.

[0049] Comparative Example 7: Please see Figure 1 The present invention provides a comparative scheme: the difference from Example 1 is that the isothermal curing step is missing, and the composite coating preparation and flat-top laser-assisted fine polishing are completed and the material is discharged directly. The remaining process steps and parameters are completely consistent with Example 1.

[0050] Comparative Example 7 lacked the isothermal curing step, resulting in the inability to release internal stress in the coating, affecting all performance indicators and achieving a product qualification rate of only 82.0%. The core function of isothermal curing is to eliminate internal stress generated during coating preparation and laser polishing, enhancing the coating's bonding stability. Without it, the density of the TiN transition layer decreased to 97.6%, and the coating adhesion dropped to 46 MPa, failing to meet the requirement of >50 MPa. The DLC functional top layer had a hardness of 2420 HV and a friction coefficient of 0.11, indicating decreased wear resistance and failing to meet the hardness limit. Simultaneously, internal stress caused surface smoothness and roughness to rebound, ultimately resulting in a surface smoothness of 0.0055 mm / cm. 2 The surface roughness Ra is 0.105 μm, both exceeding the standards defined in the claims. This demonstrates that the isothermal curing step is crucial for eliminating internal stress and stabilizing product performance; its absence leads to a significant decrease in product precision and coating quality, failing to meet usage requirements.

[0051] Based on the analysis of experimental data and results from all the above embodiments and comparative examples, it can be concluded that Examples 1-3, using three commonly used semiconductor metal substrates—6061-T6 aluminum alloy, Kovar alloy, and titanium alloy—and strictly following the process steps and parameter ranges defined in this technical solution, achieved excellent product performance through the synergistic effect of five core steps: substrate pretreatment, precision milling, composite coating preparation, flat-top laser-assisted polishing, and constant-temperature curing. The final surface flatness was as low as 0.002 mm / cm. 2 The surface roughness Ra is as low as 0.06μm, the coating adhesion is as high as 62MPa, the TiN transition layer density is as high as 99%, and the DLC functional top layer hardness is as high as 3000HV, which fully demonstrates the stability and reliability of this technical solution.

[0052] In stark contrast to the embodiments, the seven comparative examples, by omitting core process steps and deviating from key process parameters, verified the necessity and ingenuity of the limitations on each step and parameter of this technical solution. Comparative Example 1 lacked the stress-relief annealing step, Comparative Example 2 lacked the surface roughening step, Comparative Example 3 lacked the ultra-clean cleaning step, and Comparative Example 7 lacked the isothermal curing step. All of these resulted in multiple performance indicators failing to meet standards. In particular, the absence of the isothermal curing step led to surface smoothness, roughness, coating adhesion, and DLC hardness all exceeding the specified standards, highlighting the indispensable synergy of the five core steps. Comparative Example 4 deviated from the nickel-phosphorus electroless plating solution formula, Comparative Example 5 deviated from the plating solution pH value, and Comparative Example 6 deviated from the TiN transition layer sputtering parameters, similarly resulting in decreased coating quality and insufficient adhesion. This demonstrates that the precise limitation of key parameters in this technical solution is the core guarantee for achieving excellent performance, breaking through the limitations of vague parameters and chaotic steps in existing technologies.

[0053] To further illustrate the beneficial technical effects of the various embodiments of the present invention, relevant performance tests were conducted on Embodiments 1-4 and Comparative Examples 1-3; The testing method is as follows: 1. Surface flatness test: A three-dimensional coordinate measuring instrument is used for testing. Ten test points are selected evenly distributed on the surface of the constant temperature platform. The instrument measurement accuracy is adjusted, and each test point is measured three times. The coordinate data of each point is recorded. The surface flatness value is calculated by the instrument's built-in software, and the average value of the three measurements is taken as the final test result.

[0054] 2. Surface roughness test: The test sample is fixed on the instrument stage using an atomic force microscope. The scanning range and resolution are adjusted to scan and image the sample surface. The instrument automatically analyzes the scanning data and extracts the surface roughness Ra value. Three different areas of each sample are selected for testing, and the average value is taken as the final result.

[0055] 3. Coating adhesion test: The scratch test method is used to test the coating adhesion. The sample is fixed firmly, a scratch probe of appropriate specifications is selected, and a constant loading rate and scratch length are set. The coating surface is scratched and the coating is observed to see if peeling or detachment occurs at the scratch. At the same time, the critical load during the scratching process is recorded to determine the coating adhesion.

[0056] 4. TiN transition layer density test: The sample was sliced, ground and polished to make a metallographic sample. The microstructure of the TiN transition layer was observed under the microscope. The proportion of dense area to total area in the transition layer was statistically analyzed by the instrument image analysis function, and the density value was calculated.

[0057] 5. DLC Functional Top Layer Hardness Test: A Vickers hardness tester is used for testing. An appropriate test load is set, and the indenter is vertically pressed into the surface of the DLC functional top layer. After holding for a specified time, the indenter is unloaded, and the diagonal length of the indentation is measured. The Vickers hardness (HV) value is obtained by converting it into a hardness calculation formula. Five test points are selected for each sample, and the average value is taken as the final hardness result.

[0058] 6. Phosphorus content test of nickel-phosphorus electroless plating underlayer: The sample surface is cleaned to avoid interference from impurities. The nickel-phosphorus electroless plating underlayer is scanned by the energy dispersive spectroscopy (EDS) instrument. The instrument automatically analyzes the scan results and outputs the mass fraction (wt%) of phosphorus as the result of phosphorus content detection.

[0059] 7. Coating thickness test: The thickness of the nickel-phosphorus electroless plating bottom layer, TiN transition layer, and DLC functional top layer was measured using a coating thickness gauge. After calibrating the instrument, the probe was attached to the surface of the test coating to ensure that the probe was in close contact with the sample surface without tilting. Six evenly distributed test points were selected for each coating, and the thickness data of each point was recorded. The average value was taken as the final thickness of the coating.

[0060] 8. Friction coefficient test of DLC functional top layer: The friction and wear test machine is used for testing. The test load, friction speed and friction time are set. The DLC functional top layer is subjected to relative frictional motion with the standard friction pair. The instrument records the friction force data in real time during the friction process. The friction coefficient is calculated by the ratio of friction force to load. The value of the friction stable stage is taken as the final result.

[0061] 9. Product qualification rate test: A sampling inspection method is adopted. 50 finished products are sampled in each group of experiments. According to the preset qualification standards, each finished product is tested for various performance indicators. The number of products that meet all qualification standards is counted. The product qualification rate is calculated by the ratio of the number of qualified products to the total number of samples.

[0062] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific technical solutions or characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A surface smoothing process for a constant-temperature platform, wherein the constant-temperature platform is a semiconductor stage made of metal, characterized in that, Includes the following steps: S1. Substrate Pretreatment: Select semiconductor-specific metal substrates and sequentially perform stress-relief annealing, surface roughening, and ultra-clean cleaning. The stress-relief annealing involves holding at 500-700℃ for 2-4 hours and then slowly cooling to room temperature at a rate of 50-80℃ / h. The surface roughening is performed by sandblasting with corundum abrasive particles of 80-120 mesh, a sandblasting pressure of 0.3-0.5MPa, and a sandblasting time of 10-15 minutes. The ultra-clean cleaning involves sequentially performing ultrasonic solvent degreasing, alkaline degreasing, DI water rinsing, and nitrogen drying. The alkaline degreasing solution is composed of the following raw materials in parts by weight: sodium hydroxide 10-15 parts, sodium carbonate 8-12 parts, sodium silicate 5-8 parts, surfactant 2-4 parts, and deionized water 60-75 parts. S2. Precision Milling: Pre-treated metal substrates are CNC milled using carbide micro-diameter end mills. A vacuum chuck and adjustable support column combination clamping system is used. The milling speed is controlled at 8000-12000 r / min, the feed rate at 0.1-0.3 mm / r, and the depth of cut at 0.5-1.5 mm. After milling, a CAM system dynamically corrects tool wear errors to ensure the initial surface flatness of the substrate is ≤0.02 mm / cm. 2 ; S3. Composite Coating Preparation: A nickel-phosphorus electroless plating underlayer, a TiN transition layer, and a DLC functional top layer are sequentially prepared on the milled substrate surface. The nickel-phosphorus electroless plating underlayer consists of the following raw materials by weight: 25-35 parts nickel sulfate, 20-30 parts sodium hypophosphite, 8-12 parts sodium citrate, 4-6 parts sodium acetate, 1-2 parts brightener, and 100-120 parts deionized water. The plating temperature is 85-95℃, the plating time is 60-90 min, and the coating thickness is 10-15 μm. The TiN transition layer uses… The coating is prepared by magnetron sputtering with a sputtering power of 150-200W, a sputtering gas pressure of 0.1-0.3Pa, a deposition temperature of 400-500℃, a deposition time of 30-45min, and a coating thickness of 3-5μm. The functional top layer of the DLC is prepared by plasma-enhanced chemical vapor deposition with a reaction gas of a mixture of methane and argon (volume ratio 1:8-12), a reaction gas pressure of 0.5-1.0Pa, a deposition temperature of 200-300℃, a deposition time of 45-60min, and a coating thickness of 2-4μm. S4. Flat-top laser-assisted fine polishing: The Gaussian laser is modulated into a flat-top laser to perform fine polishing on the surface of the composite coating. The spot diameter is 200-500μm, the laser power is 8-12W, the polishing speed is 1500-2000r / min, and the polishing time is 20-30min. Argon gas protection is used during the polishing process to control the surface temperature fluctuation ≤±0.1℃. S5. Constant Temperature Curing and Testing: The polished metal stage is cured at 120-150℃ for 2-3 hours, cooled to room temperature, and then tested. The final surface flatness is ≤0.005mm / cm. 2 A thermostatic metal stage for semiconductors with a surface roughness Ra≤0.1μm and a coating adhesion strength>50MPa.

2. The constant temperature platform surface smoothing process according to claim 1, characterized in that, The semiconductor-specific metal substrate mentioned in step S1 is one of 6061-T6 aluminum alloy, Kovar alloy, or titanium alloy, and the substrate thickness is 5-10mm.

3. The constant temperature platform surface smoothing process according to claim 1, characterized in that, The surfactant mentioned in step S1 is fatty alcohol polyoxyethylene ether, and the brightener is a compound of sodium saccharin and polyethylene glycol with a weight ratio of 1:1.5-2.

5. The surfactant can improve the permeability of the alkaline washing solution, and the brightener can make the surface of the nickel-phosphorus electroless plating underlayer more uniform and smooth, avoiding pinholes and defects in the plating layer.

4. The constant temperature platform surface smoothing process according to claim 1, characterized in that, In step S3, the pH value of the plating solution for the nickel-phosphorus electroless plating underlayer is 4.5-5.5, the density of the TiN transition layer is ≥98%, and the hardness of the DLC functional top layer is HV2500-3000, which further improves the wear resistance, temperature resistance, and smoothness of the composite coating.

5. The constant temperature platform surface smoothing process according to claim 1, characterized in that, The pulse width of the flat-top laser in step S4 is 10-20ns, and the repetition frequency is 100-200kHz, which can precisely control the polishing depth and avoid damage to the composite coating bottom layer and substrate.

6. The constant temperature platform surface smoothing process according to claim 1, characterized in that, In step S5, the heating rate of the constant temperature curing oven is 30-50℃ / h, and natural cooling is used during the cooling process to avoid stress deformation of the stage caused by excessively rapid cooling; the qualified inspection standard is: surface flatness ≤ 0.005mm / cm 2 Surface roughness Ra≤0.1μm, coating adhesion>50MPa, defective products need to be returned to step S4 for re-polishing.

7. The constant temperature platform surface smoothing process according to claim 1, characterized in that, In step S1, the ultrasonic solvent degreasing uses ethanol as the solvent, the degreasing temperature is 40-50℃, and the degreasing time is 15-20 minutes. It can quickly remove organic oil stains from the surface of the substrate without leaving any residue or damaging the substrate.

8. The constant temperature platform surface smoothing process according to claim 1, characterized in that, In step S3, the plasma power of the plasma-enhanced chemical vapor deposition method is 80-120W, which can improve the deposition efficiency and density of the DLC functional top layer and ensure a smooth and flat coating surface.

9. The constant temperature platform surface smoothing process according to claim 1, characterized in that, The alkaline washing solution described in step S1 is prepared as follows: Weigh 10-15 parts sodium hydroxide, 8-12 parts sodium carbonate, 5-8 parts sodium silicate, 2-4 parts surfactant, and 60-75 parts deionized water by weight. First, heat the deionized water to 40-50°C, then add sodium hydroxide, sodium carbonate, and sodium silicate in sequence, stirring until completely dissolved. After cooling to room temperature, add the surfactant and continue stirring for 15-20 minutes until the solution is uniform and free of precipitate, thus obtaining the alkaline washing solution.

10. The constant temperature platform surface smoothing process according to claim 1, characterized in that, The preparation method of the nickel-phosphorus electroless plating underlayer in step S3 is as follows: Weigh 25-35 parts by weight of nickel sulfate, 20-30 parts by weight of sodium hypophosphite, 8-12 parts by weight of sodium citrate, 4-6 parts by weight of sodium acetate, 1-2 parts by weight of brightener, and 100-120 parts by weight of deionized water. Place the deionized water in a container at room temperature, add sodium citrate and sodium acetate in sequence, and stir until completely dissolved. Then add nickel sulfate and stir until dissolved. Add sodium hypophosphite and continue stirring for 30-40 minutes. Finally, add brightener and stir for 10-15 minutes. Adjust the pH value of the plating solution to 4.5-5.5 to obtain the nickel-phosphorus electroless plating underlayer.

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