Mask substrate and coating temperature control method

Abstract

The invention discloses a mask substrate and a coating temperature control method, and belongs to the technical field of semiconductor manufacturing. The mask substrate comprises a substrate body and an anti-reflection layer, a shading layer and a protection layer which are sequentially formed on the surface of the substrate body, the anti-reflection layer is a gradient composite film, the shading layer is nanocrystalline Cr, the shading layer is deposited through HiPIMS sputtering, and the grain size is lt; the deposition temperature is 280 + / -3 DEG C, and a CrON transition layer is arranged between the anti-reflection layer and the shading layer. According to the mask substrate and the coating temperature control method, the plurality of temperature sensing modules are arranged in the non-coating area at the edge of the substrate body, and the Pt1000 thin film thermocouple is combined with the Al2O3 slide glass for packaging, so that the mask substrate has good thermal response speed and measurement accuracy, the real temperature change of the surface of the substrate can be directly reflected, and the defects of the traditional external temperature measurement means are overcome; based on temperature data collected by the modules, the software system may dynamically adjust heater power.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor manufacturing, and in particular to a mask substrate and a coating temperature control method. Background Art

[0002] In semiconductor wafer processing, the quality of the mask substrate coating directly impacts the performance of the final product. Mask substrates typically require the sequential deposition of multiple thin-film structures, including antireflection layers, light-shielding layers, and protective layers. However, temperature control is crucial during the multilayer thin-film deposition process. Excessively high temperatures can cause substrate deformation or stress concentration in the film, while uneven temperatures can lead to inconsistent film composition and refractive index distribution, impacting device consistency and reliability.

[0003] In traditional mask substrate coating systems, temperature monitoring often relies on thermocouples or infrared thermometers outside the chamber. These instruments cannot accurately reflect the actual temperature of a specific region of the substrate in real time. This is especially true during high-temperature processes, where significant temperature differences exist between the substrate edge and center, leading to reduced coating uniformity. Furthermore, the lack of a removable temperature sensing module in existing mask substrates limits the ability to flexibly monitor temperatures across different process stages. Summary of the Invention

[0004] The purpose of the present invention is to provide a mask substrate and a coating temperature control method. By arranging multiple temperature sensing modules in the non-coating area at the edge of the substrate body, and using Pt1000 thin film thermocouples combined with Al2O3 carrier packaging, the present invention has good thermal response speed and measurement accuracy, can directly reflect the actual temperature changes on the substrate surface, make up for the shortcomings of traditional external temperature measurement methods, and solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solutions: a mask substrate, comprising a substrate body and an anti-reflection layer, a light-shielding layer and a protective layer sequentially formed on the surface of the substrate body, wherein the anti-reflection layer is a gradient composite film, the light-shielding layer is nanocrystalline Cr, the light-shielding layer is deposited by HiPIMS sputtering, the grain size is <15nm, the deposition temperature is 280±3°C, a CrON transition layer is provided between the anti-reflection layer and the light-shielding layer, and a temperature sensing module is provided at the edge of the substrate body, which is temporarily fixed by high-temperature resistant glue.

[0006] Preferably, the gradient composite film includes a Cr-rich transition layer, a CrN dominant layer, a CrN-CrO layer, and a CrN-CrO layer. X Graded layer and CrO-rich X In the surface layer, the oxygen content of the gradient composite film increases from the substrate body to the surface, and the nitrogen content decreases. XThe refractive index of the surface layer at a wavelength of 193nm gradually changes from 2.5 to 1.8. The composition gradient of the Cr-rich transition layer transitions from 100% Cr to the CrN layer. Nitrogen gradually increases to reduce the interface stress. The nitrogen content in the CrN dominant layer is 50-55at.%, the refractive index n≈2.3-2.5 (@193nm), the extinction coefficient k≈0.8-1.0, and the CrN-CrO X In the gradient layer, CrN gradually changes to CrO X Transition, oxygen content 60-65at.%, n≈1.8-2.0, k≈0.3-0.5.

[0007] Preferably, the thickness of the Cr-rich transition layer is in the range of 2-5 nm, which is used to enhance the adhesion with the substrate body (1); the thickness of the CrN dominant layer is in the range of 5-10 nm, which provides high hardness and thermal stability. X The thickness of the gradient layer is 3-8nm, which adjusts the refractive index gradient to achieve wide-band anti-reflection. X The main thickness of the surface layer is 2-5nm, which reduces the surface reflectivity, and the reflectivity at a wavelength of 193nm is <1%.

[0008] Preferably, the processing method of the CrON transition layer is as follows: X After surface deposition, maintain the N2 flow rate at 10 sccm and gradually introduce O2 from 5 sccm to 0 sccm for 30-60 s. Simultaneously reduce the N2 flow rate to 5 sccm to gradually change the film composition from CrON to CrN. The DC power is 200 W, the substrate body temperature is 180-220 ° C, and the pressure is 0.3-0.5 Pa to ensure plasma stability.

[0009] Preferably, the temperature sensing module is temporarily fixed to the non-coated area at the edge of the substrate body. The temperature sensing module includes a Pt1000 thin film thermocouple and an Al2O3 carrier. The Pt1000 thin film thermocouple is made of a platinum film doped with 4% Rh and the surface is covered with a 50nm Si3N4 protective layer.

[0010] Preferably, a micro-groove is laser-processed on the back edge of the substrate body, and the groove depth of the micro-groove is 0.2-0.5 mm. A 200 nm gold layer is deposited in the micro-groove by magnetron sputtering, the electrode pattern is defined by photolithography, and then the excess gold layer is etched away. ALD deposits a 50 nm Al2O3 layer to cover the sidewalls of the groove, leaving only the bottom electrode exposed.

[0011] Preferably, the installation method of the temperature sensing module is as follows: apply Al2O3-based adhesive in the micro-groove, use a vacuum suction pen to absorb the temperature sensing module, align it with the micro-groove under a microscope, apply pressure for 30 seconds to make the adhesive layer evenly fill the interface, cure it under ultraviolet irradiation for 60 seconds, lead the gold nanowire from the temperature sensing module pad to the external terminal of the substrate body, and fix it with UV glue.

[0012] The preparation method of the temperature sensing module is as follows: a platinum film is photolithographically prepared on an Al2O3 carrier, annealed at 250°C in a nitrogen environment for 1 hour to stabilize the resistance value, and a gold wire ball with a diameter of 25 μm is used to connect the platinum film to the edge pad of the Al2O3 carrier to make a temperature sensing module.

[0013] Preferably, the temperature sensing module is disassembled as follows: locally heat the micro-groove to 200°C and keep it for 2 minutes to soften the Al2O3-based adhesive. Use ceramic tweezers to clamp the edge of the temperature sensing module, apply vertical upward force, slowly pull it out, and use oxygen plasma cleaning to remove the glue stains.

[0014] Another technical problem to be solved by the present invention is to provide a method for controlling the coating temperature of a mask substrate, comprising the following steps: Step 1: Install the temperature sensing module on the substrate body and calibrate the temperature sensing module reading to an error of ±0.2°C; Step 2: Control the temperature at 180±5℃, use Ar sputtering Cr target on the upper surface of the substrate body, DC power 200W, pressure 0.4Pa, dynamically adjust the N2 and O2 flow rates to achieve refractive index gradient deposition of anti-reflection layer, the temperature rises to 200±5℃, N2 and O2 flow rates gradually control the composition, and deposit CrON transition layer; Step 3: Stop the introduction of N2 and O2 reaction gases, evacuate to 0.1 Pa to ensure that there is no residual oxygen and nitrogen, use HiPIMS to sputter the Cr target, with a pulse energy of 50 mJ, a frequency of 500 Hz, and pure Ar 50 sccm. The temperature is controlled at 280±3°C to deposit the light shielding layer 3. Cool the temperature sensing module area with helium to ≤250°C. Step 4: Transfer to the ALD chamber, and switch the gases in sequence at 120±2℃ and 5-50 Pa: use SiH4 and NH3 for 100 cycles of deposition with a growth rate of 0.1nm per cycle to form a Si3N4 film; use Ru(C5H5)2 and O2 for 20 cycles of deposition with a growth rate of 0.05nm per cycle to form a metal Ru film. This plasma-enhanced ALD process grows at low temperature and eventually forms a composite protective layer.

[0015] Preferably, the temperature sensing module collects the temperature of the substrate body, and the software displays the temperature curve. When the temperature exceeds the set range, the coating is automatically paused. At least three temperature sensing modules are arranged at the edge of the substrate body, and the average value is taken to compensate for the thermal field unevenness. The edge is usually 3-5°C lower than the center. The edge and center heater power are independently adjusted according to the module data. After the coating is completed, the constant temperature is maintained for 10 minutes to confirm that the temperature deviation of the temperature sensing module and the cavity thermocouple reading is <±0.5°C.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The mask substrate and coating temperature control method of the present invention provide multiple temperature sensing modules in the non-coating area at the edge of the substrate body, and adopt Pt1000 thin film thermocouples combined with Al2O3 carrier packaging, which have good thermal response speed and measurement accuracy, can directly reflect the actual temperature change of the substrate surface, and make up for the shortcomings of traditional external temperature measurement methods; based on the temperature data collected by the modules, the software system can dynamically adjust the heater power to compensate for the temperature difference between the edge and the center area, thereby achieving temperature consistency control over the entire substrate surface, significantly improving the uniformity of the film composition and refractive index distribution; the temperature sensing module is temporarily fixed in the laser-processed micro-groove by Al2O3-based adhesive, which is convenient to install and easy to disassemble and replace later; local heating can soften the adhesive layer to achieve non-destructive peeling, and oxygen plasma cleaning is used to remove residues to ensure the integrity of the substrate body; the anti-reflection layer adopts a gradient from Cr-rich to CrO X The gradual gradient composite film structure, combined with the composition-gradient deposition process of the CrON transition layer, effectively reduces interfacial stress, optimizes the reflectivity in the 193nm band, and improves the adhesion and thermal stability of the film. The light-shielding layer uses HiPIMS sputtered nanocrystalline Cr, and the deposition temperature is controlled at 280±3°C to ensure high density and good light-shielding performance. The protective layer uses Si3N4 and Ru layers deposited through a low-temperature ALD process, taking into account anti-oxidation, anti-corrosion and conductive properties, and adapting to complex coating environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a diagram showing the overall structure of the mask substrate of the present invention; Figure 2 This is a cross-sectional view of the mask substrate of the present invention.

[0018] In the figure: 1. Substrate body; 2. Anti-reflection layer; 3. Light-shielding layer; 4. Protective layer; 5. Temperature sensing module. DETAILED DESCRIPTION

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0020] Example 1: To solve the problem that in the existing traditional mask substrate coating system, temperature monitoring mostly relies on thermocouples or infrared thermometers outside the chamber, which cannot accurately reflect the actual temperature of the local area of the substrate body in real time, especially in the high temperature process stage, there is a significant temperature difference between the edge and the center of the substrate, which leads to a decrease in coating uniformity. Figure 1-Figure 2 , this embodiment provides the following technical solutions: A mask substrate includes a substrate body 1 made of synthetic quartz glass. A micro-groove is laser-machined on the back edge of the substrate body 1. The groove depth of the micro-groove is 0.2-0.5 mm. A 200 nm gold layer is deposited in the micro-groove by magnetron sputtering. An electrode pattern is defined by photolithography, and then the excess gold layer is etched away. A 50 nm Al2O3 layer is deposited by ALD to cover the groove sidewalls, leaving only the bottom electrode exposed.

[0021] A platinum film was photolithographically prepared on an Al2O3 wafer. A Pt1000 thin-film thermocouple was fabricated using a 4% Rh-doped platinum film covered with a 50nm Si3N4 protective layer. The film was then annealed at 250°C in a nitrogen atmosphere for 1 hour to stabilize the resistance. A 25μm-diameter gold wire ball was then used to connect the platinum film to the edge pads of the Al2O3 wafer to form a temperature sensing module 5. An Al2O3-based adhesive was applied to the micro-grooves. The temperature sensing module 5 was then aspirated using a vacuum pen and aligned with the micro-grooves under a microscope. Pressure was applied and maintained for 30 seconds to ensure that the adhesive layer evenly filled the interface. The module was then cured by UV irradiation for 60 seconds. Gold nanowires were then guided from the pads of the temperature sensing module 5 to the external terminals of the substrate body 1 and fixed with UV adhesive. Three temperature sensing modules 5 were then installed, and the readings of the temperature sensing modules 5 were calibrated.

[0022] Select a certified standard thermometer with an accuracy of ±0.1°C. Prepare a thermostat and set a series of predetermined temperatures: 50°C, 100°C, 150°C, 200°C, 250°C, and 300°C. Place the Pt1000 thin-film thermocouple module and the standard thermometer in the bath simultaneously, ensuring they are in full contact with the heat transfer medium and as close together as possible to maintain the same temperature environment. At each set temperature, wait 15 minutes for the system to reach thermal equilibrium. Record the temperature displayed by the standard thermometer and the reading of the Pt1000 thin-film thermocouple module. Compare the difference between the Pt1000 thin-film thermocouple module reading and the standard thermometer reading at each temperature point. If the deviation exceeds ±0.2°C, adjust the calibration parameters of the Pt1000 thin-film thermocouple module based on the actual error. After completing the initial calibration, rerun the entire test process to recheck that the Pt1000 thin-film thermocouple module meets the error requirement of ±0.2°C at all selected temperature points.

[0023] The substrate body 1 is heated to 280°C, and the Pt1000 thin film thermocouple monitors the temperature of each point in real time. The target temperature curve is set: the ideal operating temperature curve is set according to the process requirements, and 280±3°C is maintained during the coating deposition cycle. Data is acquired from all sensors every second, and the average temperature and the maximum temperature difference between the edge and the center are calculated. The proportional-integral-differential (PID) controller is used to automatically adjust the output power of the edge and center heaters according to the difference between the actual measured value and the target value. If the edge temperature is lower than the center, the power of the edge heater is increased; otherwise, it is reduced. The system status is re-evaluated every 10 seconds, and the PID parameters are adjusted according to the latest temperature distribution to optimize the response speed and smoothness. As a result, the maximum temperature difference between the edge and the center is controlled within ±1°C.

[0024] Example 2: Control the temperature at 180±5℃, use Ar sputtering Cr target on the upper surface of substrate body 1, DC power 200W, pressure 0.4Pa, dynamically adjust the flow of N2 and O2 to achieve refractive index gradient deposition anti-reflection layer 2, N2 / O2 flow ratio gradually changes from 20 / 0 to 5 / 25, and the Cr-rich transition layer, CrN dominant layer, CrN-CrO layer, etc. are formed on the surface of substrate body (1) in sequence. X Graded layer and CrO-rich X The composition gradient of the Cr-rich transition layer transitions from 100% Cr to the CrN layer, and the nitrogen gradually increases from 20 sccm to 30 sccm. At 200W DC and 0.4Pa, the Cr-rich transition layer reduces the interface stress. The nitrogen content in the CrN dominant layer is 50-55at.%, maintaining N230sccm. The temperature is stabilized at 180℃ and the deposition rate is 0.2nm / s. X In the gradient layer, CrN gradually changes to CrOX Transition, N2 linearly decreased from 30sccm to 5sccm, O2 increased from 0 to 25sccm, completed within 60s, CrO-rich X Surface O2 25sccm, temperature 180℃, reflectivity real-time monitoring.

[0025] The temperature rises to 200±5℃, the N2 flow rate is maintained at 10sccm, and O2 is gradually introduced from 5sccm to 0sccm for 30-60s to deposit the CrON transition layer. The N2 flow rate is simultaneously reduced to 5sccm to gradually change the film composition from CrON to CrN. The DC power is 200W, the pressure is 0.4Pa, and the thickness is 3nm.

[0026] Stop the introduction of reaction gases N2 and O2, evacuate to 0.1 Pa, ensure that there is no residual oxygen and nitrogen, use HiPIMS to sputter the Cr target, with a pulse energy of 50 mJ, a frequency of 500 Hz, pure Ar 50 sccm, and a temperature control of 280±3°C to deposit the light shielding layer 3, and cool the temperature sensing module (5) area with helium to ≤250°C.

[0027] The film was transferred to the ALD chamber and switched in sequence at 120±2°C and a pressure of 5-50 Pa. SiH4 and NH3 were used for 100 cycles of deposition at a growth rate of 0.1 nm per cycle to form a Si3N4 film. Ru(C5H5)2 and O2 were used for 20 cycles of deposition at a growth rate of 0.05 nm per cycle to form a metal Ru film. This plasma-enhanced ALD process grew at low temperature and eventually formed a composite protective layer.

[0028] After the coating is completed, the constant temperature is maintained for 10 minutes to confirm that the deviation between the temperature of the temperature sensing module 5 and the reading of the cavity thermocouple is less than ±0.5°C.

[0029] The micro-grooves were locally heated to 200°C for 2 minutes to soften the Al2O3-based adhesive. The edge of the temperature sensing module 5 was clamped with ceramic tweezers, and vertical force was applied upward. The module was slowly pulled out and the adhesive stains were removed using oxygen plasma cleaning.

[0030] The prepared mask substrate was subjected to performance testing and the following data table was obtained: index result Reflectivity (193nm) 0.6% Film adhesion ＞30N Graphic CD uniformity ±1.0% Module temperature measurement error ±0.2℃ Substrate warpage 0.08μm / cm Comparative Example 1: The Pt1000 sensor is directly embedded in the substrate without using the micro-groove + Al2O3 adhesive installation method. The Pt1000 sensor cannot be replaced, and the anti-reflection layer 2, the light shielding layer 3 and the protective layer 4 are processed using the method of Example 2.

[0031] The prepared mask substrate was subjected to performance testing and the following data table was obtained: index result Reflectivity (193nm) 1.5% Film adhesion 20N Graphic CD uniformity ±1.2% Module temperature measurement error ±1℃ Substrate warpage 0.10μm / cm In this comparative example, the non-detachable design of the Pt1000 sensor makes maintenance difficult and reduces temperature measurement accuracy, affecting long-term process stability.

[0032] Comparative Example 2: The substrate body 1 and the temperature sensing module 5 were processed using the method of Example 1, and the anti-reflection layer 2, the light-shielding layer 3, and the protective layer 4 were processed using the method of Example 2. The anti-reflection layer 2 was in direct contact with the light-shielding layer 3, and there was no CrON transition layer. The light-shielding layer 3 was deposited at a temperature of 300°C. The prepared mask substrate was subjected to performance testing, and the following data table was obtained: index result Reflectivity (193nm) 2.8% Film adhesion 12N Graphic CD uniformity ±2.5% Module temperature measurement error ±0.2℃ Substrate warpage 0.5μm / cm The lack of gradient film design in this comparative example leads to decreased optical performance and unstable film quality.

[0033] In summary, the present invention proposes a mask substrate and coating temperature control method, which introduces a detachable Pt1000 thin-film thermocouple module and uses a micro-groove + Al2O3 adhesive installation method to achieve high-precision, reusable local temperature monitoring. The gradient composite anti-reflection layer and CrON transition layer design effectively improve the film adhesion, optical performance and thermal stability. The intelligent temperature control system can dynamically adjust the heating power according to module feedback, significantly improving the coating uniformity and consistency. In comparison, traditional solutions have problems such as inaccurate temperature measurement, many film defects, and inconvenient maintenance, making it difficult to meet the needs of high-precision photolithography mask manufacturing.

[0034] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0035] While the embodiments of the present invention have been shown and described, it will be apparent to those skilled in the art that various changes, modifications, substitutions, and alterations can be made to the embodiments without departing from the principles and spirit of the invention.

Claims

1. A mask substrate, comprising a substrate body (1) and an anti-reflection layer (2), a light shielding layer (3) and a protective layer (4) sequentially formed on the surface of the substrate body (1), wherein: The anti-reflection layer (2) is a gradient composite film, the light-shielding layer (3) is nanocrystalline Cr, the light-shielding layer (3) is deposited by HiPIMS sputtering, the grain size is less than 15nm, and the deposition temperature is 280±3°C. A CrON transition layer is provided between the anti-reflection layer (2) and the light-shielding layer (3), and a detachable temperature sensing module (5) is provided at the edge of the substrate body (1), and the temperature sensing module (5) is temporarily fixed by a high-temperature resistant glue.

2. The mask substrate according to claim 1, wherein: The gradient composite film comprises a Cr-rich transition layer, a CrN dominant layer, a CrN-CrO layer, and a CrN-CrO layer, which are sequentially formed on the surface of the substrate body (1). X Graded layer and CrO-rich X In the surface layer, the oxygen content of the gradient composite film increases from the substrate body (1) to the surface, and the nitrogen content decreases, and the Cr-rich transition layer to the CrO-rich transition layer X The refractive index of the surface layer changes gradually from 2.5 to 1.8 at a wavelength of 193nm.

3. The mask substrate according to claim 2, wherein: The thickness of the Cr-rich transition layer is in the range of 2-5 nm, the thickness of the CrN dominant layer is in the range of 5-10 nm, and the CrN-CrO X The thickness of the graded layer is 3-8nm, CrO X The main thickness of the surface layer is 2-5nm.

4. The mask substrate according to claim 3, wherein: The processing method of the CrON transition layer is as follows: X After surface deposition, the N2 flow rate was maintained at 10 sccm, and O2 was gradually introduced from 5 sccm to 0 sccm for 30-60 s. The N2 flow rate was simultaneously reduced to 5 sccm, so that the film composition gradually changed from CrON to CrN. The DC power was 200 W, the substrate body (1) temperature was 180-220 °C, and the pressure was 0.3-0.5 Pa.

5. The mask substrate according to claim 4, wherein: The temperature sensing module (5) is temporarily fixed to the non-coated area at the edge of the substrate body (1). The temperature sensing module (5) includes a Pt1000 thin film thermocouple and an Al2O3 carrier. The Pt1000 thin film thermocouple is made of a platinum film doped with 4% Rh and the surface is covered with a 50nm Si3N4 protective layer.

6. The mask substrate according to claim 5, wherein: The back edge of the substrate body (1) is laser-machined with a micro-groove, the groove depth of the micro-groove being 0.2-0.5 mm. A 200 nm gold layer is deposited in the micro-groove by magnetron sputtering, the electrode pattern is defined by photolithography, and then the excess gold layer is etched away. A 50 nm Al2O3 layer is deposited by ALD to cover the sidewalls of the groove, leaving the bottom electrode exposed.

7. The mask substrate according to claim 6, wherein: The temperature sensing module (5) is installed as follows: Al2O3-based adhesive is applied in the micro-groove, the temperature sensing module (5) is sucked up with a vacuum pen, aligned with the micro-groove under a microscope, pressure is applied and maintained for 30 seconds so that the adhesive layer evenly fills the interface, and cured by ultraviolet irradiation for 60 seconds. The gold nanowire is led from the pad of the temperature sensing module (5) to the external terminal of the substrate body (1) and fixed with UV glue.

8. The mask substrate according to claim 7, wherein: The disassembly method of the temperature sensing module (5) is as follows: locally heat the micro groove to 200°C and keep it for 2 minutes to soften the Al2O3-based adhesive, clamp the edge of the temperature sensing module (5) with ceramic tweezers, apply force vertically upward to pull it out, and use oxygen plasma cleaning to remove the glue stains.

9. A method for controlling the coating temperature of a mask substrate according to claim 8, characterized in that: The following steps are involved: Step 1: Install the temperature sensing module (5) on the substrate body (1), and calibrate the temperature sensing module (5) reading to an error of ±0.2°C; Step 2: Control the temperature at 180±5°C, use Ar sputtering Cr target on the upper surface of the substrate body (1), DC power 200W, pressure 0.4Pa, dynamically adjust the flow of N2 and O2 to achieve refractive index gradient deposition of anti-reflection layer (2), the temperature rises to 200±5°C, the flow of N2 and O2 gradually controls the composition, and deposits CrON transition layer; Step 3: Stop the introduction of reaction gases N2 and O2, evacuate to 0.1 Pa, ensure that there is no residual oxygen and nitrogen, use HiPIMS to sputter the Cr target, with a pulse energy of 50mJ, a frequency of 500Hz, pure Ar 50sccm, and a temperature control of 280±3℃, deposit the light shielding layer (3), and cool the temperature sensing module (5) area with helium to ≤250℃; Step 4: Transfer to the ALD chamber, and switch the gases in sequence at 120±2℃ and 5-50 Pa: use SiH4 and NH3 for 100 cycles of deposition with a growth rate of 0.1nm per cycle to form a Si3N4 film; use Ru(C5H5)2 and O2 for 20 cycles of deposition with a growth rate of 0.05nm per cycle to form a metal Ru film. The plasma-enhanced ALD process grows at low temperature to eventually form a composite protective layer.

10. The method for controlling the coating temperature of a mask substrate according to claim 9, wherein: The temperature sensing module (5) collects the temperature of the substrate body (1), and the software displays the temperature curve. When the temperature exceeds the set range, the coating is automatically suspended. At least three temperature sensing modules (5) are arranged at the edge of the substrate body (1), and the average value is taken to compensate for the thermal field unevenness. The edge and center heater powers are independently adjusted according to the module data. After the coating is completed, the constant temperature is maintained for 10 minutes to confirm that the deviation between the temperature of the temperature sensing module (5) and the cavity thermocouple reading is <±0.5°C.

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