A protection structure for inhibiting abnormal discharge of a helium hole of an electrostatic chuck and a preparation method thereof
By constructing a multi-layer protective structure consisting of an atomic layer deposition film, a yttrium oxide ceramic bushing, and a fluororubber sealing ring on an electrostatic chuck, the problem of abnormal discharge through helium gas holes was solved, thereby achieving substrate protection and improved process stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JIHUA LAB
- Filing Date
- 2026-05-29
- Publication Date
- 2026-07-07
AI Technical Summary
The helium gas holes of existing electrostatic chucks are prone to abnormal discharge in high-power, high-frequency plasma process environments, which can damage the devices on the substrate surface. Existing protection technologies are insufficient to effectively block plasma penetration and ensure long-term stability.
A first protective film with a surface roughness of less than 3 nm was prepared using atomic layer deposition technology. Combined with a yttrium oxide ceramic bushing and a fluororubber sealing ring, a multi-layer synergistic protection system was constructed to achieve tight fit and high-temperature sealing, thereby blocking the discharge path.
It significantly reduces the electric field intensity in the helium hole region, avoids damage to the circuitry on the back of the substrate, improves process stability and wafer yield, and is suitable for high-end process equipment such as etching, PVD, and CVD.
Smart Images
Figure CN122349342A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor technology, and mainly to a protective structure and preparation method for suppressing abnormal discharge of helium gas holes in an electrostatic chuck. Background Technology
[0002] Electrostatic chucks (ESCs), as core components for wafer transport and fixation in semiconductor manufacturing equipment, play an irreplaceable role in key processes such as etching, physical vapor deposition (PVD), and chemical vapor deposition (CVD) due to their advantages such as uniform clamping force, no mechanical damage, and strong adaptability to vacuum environments. They firmly fix the substrate (wafer) to the chuck surface through electrostatic adsorption, ensuring heat conduction and positional stability during the process. Helium (He), as the back-side cooling gas, permeates through helium gas holes on the chuck surface into the tiny gap between the substrate and the chuck, achieving efficient heat conduction and being a crucial factor in ensuring precise control of process temperature.
[0003] However, in high-power, high-frequency plasma processing environments, the helium gas port structure of electrostatic chucks becomes a potential source of reliability risk. In existing technologies, the helium gas port typically penetrates directly through the chuck body (mostly a metal or conductive ceramic substrate). When the plasma density or RF bias voltage within the process chamber is high, active gas ions can easily cause abnormal discharges through the helium gas port. The high-energy particles generated by these abnormal discharges directly bombard the back of the substrate, causing irreversible electrical damage to precision devices or circuits on the substrate surface, such as gate oxide breakdown and transistor threshold voltage drift. This severely reduces chip yield, especially in advanced processes of 7nm and below, where such problems have become a key bottleneck restricting process stability.
[0004] In existing technologies, the following technical approaches have been attempted to solve the problem of abnormal discharge in helium gas pores, but all of them have significant defects and shortcomings: (1) Simple ceramic coating protection technology: Some solutions attempt to coat the surface of the electrostatic chuck with a corrosion-resistant ceramic layer (such as yttrium oxide coating) to block plasma. However, due to the limitations of traditional thermal spraying processes (such as plasma spraying), the coating surface roughness is high (Ra is usually > 1 μm), and there are micropores and gaps between the coating and the substrate. At the edge of the helium gas hole, this rough coating is difficult to form a dense sealing structure, and plasma can still penetrate through the micropores at the coating defects and trigger discharge. In addition, the adhesion between the coating and the substrate is insufficient, and it is prone to peeling under long-term thermal cycling, resulting in protection failure.
[0005] (2) Mechanical seal structure optimization scheme: Another technology attempts to optimize the mechanical structure around the helium gas port, such as adding a labyrinth seal or using a high-temperature adhesive seal. However, the increased complexity of the mechanical structure not only increases the processing cost and assembly difficulty, but also makes it easy for the high-temperature adhesive to age and decompose in high-temperature (>150℃) and highly corrosive plasma environments, resulting in a rapid decline in sealing performance, which cannot meet the stringent requirements of semiconductor processes for long-term stability.
[0006] (3) Limitations of Single-Layer Protective Technology: Although existing technologies mention the use of atomic layer deposition (ALD) to prepare protective films, they are mostly limited to single-material systems (such as using only ALD alumina) and do not consider the synergistic effect of multi-layer composite structures. Although a single ALD layer can reduce surface roughness, its thickness is usually only tens of nanometers. Faced with the continuous bombardment of high-energy plasma, its protective ability is limited, and it is difficult to meet the dual requirements of corrosion resistance and mechanical strength. More importantly, existing technologies have not realized the key role of the low-roughness interface of ALD in promoting the tight bonding of multi-layer protective structures, resulting in insufficient interlayer bonding and the formation of new discharge channels.
[0007] To address the aforementioned technical bottlenecks, existing electrostatic chuck protection technologies still face core issues such as poor adhesion due to surface roughness, limited performance of a single protective layer, and high-temperature sealing failure, making it difficult to fundamentally solve the substrate damage caused by abnormal discharge of helium gas holes.
[0008] Therefore, existing technologies still need to be improved and developed. Summary of the Invention
[0009] In view of the shortcomings of the prior art, the purpose of this application is to provide a protective structure and preparation method for suppressing abnormal discharge of helium gas holes in an electrostatic chuck, aiming to obtain an electrostatic chuck with an atomically flat interface, multi-layer synergistic protection, and reliable high-temperature sealing.
[0010] The technical solution of this application is as follows: A method for preparing a protective structure to suppress abnormal discharge of helium gas orifice in an electrostatic chuck includes the following steps: A first protective film is deposited on the surface of an electrostatic chuck substrate; the surface roughness of the first protective film Ra < 3 nm; A yttrium oxide ceramic bushing is placed in the helium pore area on the surface of the electrostatic chuck substrate, and vacuum-assisted pressing technology is used to make the yttrium oxide ceramic bushing tightly bonded to the first protective film, with an interface contact gap of <1μm. A fluororubber sealing ring is used to seal the joint area between the edge of the yttrium oxide ceramic bushing and the electrostatic chuck substrate.
[0011] Furthermore, the first protective film comprises one or more of the following: aluminum oxide film, titanium nitride film, and titanium oxide film. The thickness of the first protective film is 1-100nm.
[0012] Furthermore, the vacuum-assisted pressing technology includes: The electrostatic chuck substrate and the yttrium oxide ceramic bushing on which the first protective film is deposited are subjected to vacuum degassing; In a vacuum environment, the yttrium oxide ceramic bushing is placed on the surface of the electrostatic chuck substrate in the area corresponding to the helium gas hole, but the yttrium oxide ceramic bushing does not cover the helium gas hole; Inert gas is introduced for protection, and a uniform pressure of 0.1-1 MPa is applied to make the yttrium oxide ceramic bushing in surface contact with the first protective film. Maintain pressure for 5-20 minutes, then release the pressure.
[0013] Furthermore, the sealing treatment of the joint area between the edge of the yttrium oxide ceramic bushing and the electrostatic chuck substrate using a fluororubber sealing ring includes: The yttrium oxide ceramic bushing has an annular groove around its periphery, into which the fluororubber sealing ring is embedded, so that the fluororubber sealing ring is in a compressed state with a deformation of 15%-30%.
[0014] Furthermore, when the first protective film is an alumina film, the process includes the following steps: controlling the chamber temperature to 150℃-200℃, the flow rate to 50sccm-500sccm, and the chamber pressure to 0.1Torr-10Torr; the precursor pulse time to 0.1 seconds-2 seconds; introducing aluminum source precursor and oxidant, and cyclically depositing to form the alumina film.
[0015] Furthermore, the aluminum source precursor includes trimethylaluminum, and the oxidant includes one or a mixture of two of H2O and O3.
[0016] Furthermore, before depositing the first protective film on the surface of the electrostatic chuck substrate, the surface of the electrostatic chuck substrate is subjected to plasma cleaning and activation treatment.
[0017] Furthermore, the thickness of the yttrium oxide ceramic bushing is 0.5-2 mm.
[0018] This application also provides a protective structure for suppressing abnormal discharge of helium gas holes in an electrostatic chuck, which is disposed on the surface of the electrostatic chuck substrate. The protective structure includes a first protective film, a yttrium oxide ceramic bushing, and a fluororubber sealing ring. The first protective film is deposited on the surface of the electrostatic chuck substrate; The yttrium oxide ceramic bushing is embedded in the surface of the electrostatic chuck substrate on which the first protective film is deposited, and the yttrium oxide ceramic bushing is placed in the area of the electrostatic chuck substrate surface corresponding to the helium gas hole. The yttrium oxide ceramic bushing has an annular groove on its outer periphery, and the fluororubber sealing ring is fixedly connected to the yttrium oxide ceramic bushing at the corresponding annular groove.
[0019] Furthermore, the depth of the annular groove is 70%-90% of the cross-sectional diameter of the fluororubber sealing ring.
[0020] Compared with the prior art, this application has the following beneficial effects: (1) Tight interface bonding and excellent adhesion: The first protective film is prepared by atomic layer deposition (ALD) technology to obtain a nanoscale smooth interface with a surface roughness (Ra<3nm), which effectively eliminates the micropores and step effect in the traditional process. By selecting materials with high lattice matching with yttrium oxide ceramics, such as alumina, titanium oxide, or titanium nitride, the physical adsorption and chemical bonding forces between the ALD layer and the second yttrium oxide ceramic bushing are significantly enhanced, achieving a tight molecular-level bond and eliminating the risk of partial discharge caused by interface delamination.
[0021] (2) Multi-layer synergistic protection with strong insulation reliability: A three-level protection system is constructed, consisting of "ALD dense insulation layer - yttrium oxide ceramic anti-corrosion bushing - fluororubber edge seal". The first protective film effectively blocks the electric field leakage of the inner wall of the helium gas hole. The yttrium oxide ceramic further shields abnormal discharge with its high resistivity and excellent plasma resistance. The fluororubber sealing ring precisely seals the edge gap of the bushing to prevent process gas from penetrating and conducting. The synergistic effect of the three fundamentally cuts off the discharge path and greatly reduces electrical damage to the substrate devices.
[0022] (3) Strong process adaptability and high structural stability: The ALD process temperature is low (150-200℃), which does not affect the performance of the electrostatic chuck substrate and can uniformly cover the inner wall of complex channels; the yttrium oxide ceramic bushing is assembled by vacuum-assisted pressing, and the coefficient of thermal expansion matches well with the first protective film, maintaining structural integrity in frequent temperature rise and fall cycles; the fluororubber sealing ring has excellent compression resilience and high temperature and radiation resistance, ensuring sealing reliability under long-term service.
[0023] (4) Solving industry pain points and improving product yield: This application specifically solves the micro-discharge problem caused by the helium hole structure defect of the existing electrostatic chuck in the high-power plasma environment, avoids the back circuit of the wafer being bombarded or broken down by ions, significantly improves the process stability and wafer yield in the semiconductor manufacturing process, and is applicable to high-end process equipment such as etching, PVD, and CVD, and has important industrial application value. Attached Figure Description
[0024] Figure 1 This is an SEM image of the surface of the electrostatic chuck substrate on which the first protective film is deposited in Embodiment 1 of this application.
[0025] Figure 2 This is an AFM three-dimensional topographic image of the surface of the electrostatic chuck substrate on which the first protective film is deposited in Example 1 of this application. The image clearly shows that the surface undulations are minimal within the test area.
[0026] Figure 3 , Figure 4 The remaining AFM test images are of the surface of the electrostatic chuck substrate on which the first protective film is deposited in Example 1 of this application.
[0027] Figure 3 The table shows that the measured root mean square surface roughness Ra value is 0.988 nm; Figure 4 The test range of the 5μm×5μm region is shown, which intuitively proves that the atomically flat interface was successfully prepared in step one, providing strong support for the reliability of subsequent process steps. Detailed Implementation
[0028] This application provides a protective structure and preparation method for suppressing abnormal discharge of helium gas orifices in electrostatic chucks. To make the objectives, technical solutions, and effects of this application clearer and more explicit, the following provides a more detailed description. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.
[0029] This application provides a method for preparing a protective structure to suppress abnormal discharge of helium gas orifice in an electrostatic chuck, comprising the following steps: Step 1: Pretreatment of the electrostatic chuck substrate surface and deposition of the first protective film of ALD: The surface of the electrostatic chuck substrate is activated by plasma cleaning. Then, atomic layer deposition (ALD) technology is used to deposit the first protective film on the chuck surface and the inner wall of the helium orifice. This ensures that the film has atomic-level flatness and high density, so as to achieve initial insulation protection for the helium orifice and provide an excellent interface bonding basis for subsequent layers.
[0030] Specifically: Select a precision-machined electrostatic chuck substrate and first place it in an O2 plasma environment for 3-5 minutes to remove surface organic contaminants and increase surface energy.
[0031] The electrostatic chuck substrate is then loaded into the ALD deposition chamber, and the chamber conditions are controlled as follows: temperature 150℃-200℃; flow rate 50sccm-500sccm; high-purity nitrogen or argon gas; chamber pressure 0.1Torr-10Torr; precursor pulse time 0.1 seconds-2 seconds. An aluminum source precursor (such as trimethylaluminum TMA) and an oxidant (H2O or O3) are introduced, and alumina (Al2O3) films with a thickness of 1-100 nm (preferably 20-50 nm) are formed through cyclic deposition; or, a titanium source precursor is used, and nitrogen or oxidant is introduced alternately to prepare titanium nitride (TiN) or titanium oxide (TiO2) films with a thickness of 1-100 nm (preferably 20-50 nm).
[0032] The titanium source precursor is titanium tetrachloride or tetradimethylaminotitanium; it has high reactivity, good volatility and is not prone to producing impurity residues.
[0033] The nitrogen source is ammonia.
[0034] The oxidant is H2O or O3. Specifically, in the preparation of titanium nitride, titanium source and nitrogen source (such as ammonia) are introduced alternately; in the preparation of titanium oxide, titanium source and oxidant (such as water or ozone) are introduced alternately.
[0035] The ALD coating (first protective film) has a surface roughness Ra < 3nm, exhibiting excellent uniformity and conformality. It can completely cover the inner wall of the helium pores and form a dense insulating layer without pinhole defects. This low-roughness surface can effectively improve the interfacial adhesion with the second layer of yttrium oxide ceramic bushing, reduce the local electric field concentration caused by micropores, and enhance the interlayer bonding strength to prevent delamination.
[0036] Step 2: Assembly of the second functional structure of the yttrium oxide ceramic bushing: A dense yttrium oxide (Y2O3) ceramic bushing is prepared and embedded into a designated area on the surface of an electrostatic chuck substrate on which the first protective film has been deposited, ensuring that the bushing and the first protective film achieve surface contact and bonding, forming a second plasma anti-corrosion and electric field shielding structure.
[0037] High-purity yttrium oxide ceramic material was used to prepare sheet-like bushings with a thickness of 0.5-2 mm through isostatic pressing sintering. These bushings were precisely cut according to the chuck's working area layout (cutting to ensure the helium gas orifice remained unobstructed while covering all other areas), and then fitted onto the surface of an electrostatic chuck substrate with a first protective film deposited on it. During assembly, vacuum-assisted pressing technology was used to ensure a tight fit between the yttrium oxide ceramic bushing and the first protective film, with an interface contact gap of <1 μm.
[0038] Vacuum-assisted pressing technology specifically includes the following steps: 1. Vacuum degassing: Place the electrostatic chuck substrate with the first protective film deposited and the yttrium oxide ceramic bushing to be assembled in the vacuum chamber, and evacuate to (0.9-1.1)×10⁻⁶. -1 Pa and maintain for 10-20 minutes to remove gas molecules adsorbed at the interface.
[0039] 2. Alignment and Placement: In a vacuum environment, place the yttrium oxide ceramic bushing on the surface of the electrostatic chuck substrate in the area corresponding to the helium gas hole.
[0040] 3. Pressure molding: Inert gas is filled for protection, and a uniform pressure of 0.1-1MPa is applied. The pressure is transmitted to the surface of the yttrium oxide ceramic bushing through a fluid medium, so that the yttrium oxide ceramic bushing and the first protective film can make surface contact.
[0041] 4. Pressure holding and curing: Maintain pressure for 5-20 minutes and then slowly release the pressure.
[0042] Yttrium oxide ceramics have high resistivity, excellent resistance to plasma etching, and low secondary electron emission coefficient, which can effectively block the electric field from escaping from the edge of the helium gas hole and suppress wafer damage caused by micro-discharge. At the same time, its thermal expansion coefficient matches well with the ALD layer, ensuring structural stability under temperature cycling conditions.
[0043] Step 3: Bushing edge sealing and integrated encapsulation: Fluororubber sealing rings are used to seal the joint area between the edge of the yttrium oxide ceramic bushing and the electrostatic chuck substrate to prevent process gases from seeping into the internal structure and avoid the formation of partial discharge paths, thereby constructing a complete multi-layer synergistic protection system.
[0044] An annular groove is set around the yttrium oxide ceramic bushing, into which a high-temperature and radiation-resistant fluororubber sealing ring (such as FKM or FFKM material) is embedded, and the fluororubber sealing ring is compressed. Dynamic sealing is achieved by the pre-tightening force applied by the compression deformation of the fluororubber sealing ring.
[0045] Fluororubber seals are designed to maintain a deformation of 15%-30% under compression, ensuring good resilience and sealing reliability even in vacuum and high-temperature environments (up to 200°C).
[0046] Regarding dynamic sealing: 1. Interference fit design: The depth of the annular groove is designed to be 70%-90% of the diameter of the fluororubber sealing ring (i.e., reserving 10%-30% for compression). For example, when using a fluororubber sealing ring with a wire diameter of 2.62mm, the groove depth is set to 2.1mm-2.3mm, utilizing the elastic deformation of the fluororubber sealing ring under pressure to generate the initial sealing pressure.
[0047] 2. Flange locking: The electrostatic chuck flange is locked to the reaction chamber base flange by bolt assembly, and axial clamping force is applied to compress the fluororubber sealing ring, so that the fluororubber sealing ring always maintains tight contact with the mating surface in vacuum and high temperature environments.
[0048] 3. Dynamic compensation: Utilizing the low compression set of fluororubber material at high temperatures (up to 250℃), the rebound force of the sealing ring (i.e. the pre-tightening force mentioned above) can compensate for the interface gap in real time during the thermal cycle of frequent temperature rise and fall of the equipment, preventing process gas leakage.
[0049] This edge-sealing structure blocks process gases (such as He, O2, CF4) from penetrating into the internal helium channel and electrode area, preventing abnormal discharge caused by the formation of conductive paths due to gas ionization. Ultimately, a three-in-one composite protection system of "ALD nano-protective layer - yttrium oxide ceramic functional bushing - fluororubber edge seal" is formed, which significantly reduces the electric field intensity in the helium hole area, eliminates the generation of micro-plasma, and ensures the safety of devices and circuits on the substrate surface.
[0050] This application also provides a protective structure for suppressing abnormal discharge of helium gas holes in an electrostatic chuck, which is disposed on the surface of the electrostatic chuck substrate and includes a first protective film, a yttrium oxide ceramic bushing, and a fluororubber sealing ring.
[0051] The first protective film is deposited on the surface of the electrostatic chuck substrate.
[0052] The yttrium oxide ceramic bushing is embedded on the surface of the electrostatic chuck substrate on which the first protective film has been deposited. The yttrium oxide ceramic bushing is placed in the area of the electrostatic chuck substrate with helium gas holes on the corresponding surface, but the yttrium oxide ceramic bushing does not cover the helium gas holes, so that the helium gas holes are unobstructed and can work normally.
[0053] The yttrium oxide ceramic bushing has an annular groove on its outer periphery, and a fluororubber sealing ring is fixedly connected to the corresponding annular groove on the yttrium oxide ceramic bushing. The depth of the annular groove is designed to be 70%-90% of the cross-sectional diameter of the fluororubber sealing ring, so that the fluororubber sealing ring is in a compressed state to apply preload and form an interference fit.
[0054] The present application will be further described below through specific embodiments.
[0055] Example 1 To address the problem of wafer circuit damage caused by abnormal discharge of helium gas holes in electrostatic chucks during semiconductor etching processes, a composite protection system consisting of "ALD dense layer - yttrium oxide ceramic bushing - fluororubber edge seal" was constructed using the method provided in this application. The effectiveness of this system in blocking discharge paths and its process stability were verified.
[0056] The specific steps are as follows: Step 1: Pretreatment of the electrostatic chuck substrate surface and deposition of the first protective film of ALD: A precision-ground aluminum-based electrostatic chuck substrate is selected and first placed in an O2 plasma environment for 5 minutes to remove surface organic contaminants and increase surface energy.
[0057] The aluminum-based electrostatic chuck substrate was then loaded into the ALD deposition chamber, the chamber temperature was controlled at 180°C, and the aluminum source precursor (trimethylaluminum TMA) and oxidant (H2O) were introduced to form an aluminum oxide (Al2O3) film with a thickness of 30 nm through cyclic deposition.
[0058] After deposition, the surface roughness Ra of the first protective film was found to be less than 3 nm, exhibiting excellent uniformity and conformity. It completely covered the inner wall of the helium pores and formed a dense insulating layer without pinhole defects, providing an atomically smooth interface foundation for subsequent layers.
[0059] Step Two: Assembly of the Second Layer Functional Structure of the Yttrium Oxide Ceramic Bushing A sheet bushing with a thickness of 1 mm was prepared by using high-purity yttrium oxide (Y2O3) ceramic material and isostatic pressing sintering process.
[0060] Based on the layout of the helium gas holes in the working area of the chuck, the yttrium oxide ceramic bushing is precisely cut (the cutting ensures that the helium gas holes remain unobstructed while covering other areas except for the helium gas holes), and then embedded into the designated area on the surface of the electrostatic chuck (the area on the surface of the electrostatic chuck corresponding to the helium gas holes) after the first protective film has been deposited.
[0061] During the assembly process, a pressure of 0.5 MPa is applied using a vacuum-assisted pressing device to achieve surface contact bonding between the yttrium oxide ceramic bushing and the first protective film.
[0062] Vacuum-assisted pressing technology specifically refers to: 1. Vacuum Degassing: Place the electrostatic chuck with the first protective film to be deposited and the yttrium oxide ceramic bushing in the vacuum chamber, and evacuate to 1×10⁻⁶. -1 Pa and maintain for 15 minutes to remove gas molecules adsorbed at the interface.
[0063] 2. Alignment and Placement: In a vacuum environment, place the yttrium oxide ceramic bushing on the surface of the electrostatic chuck in the area corresponding to the helium gas hole.
[0064] 3. Pressure molding: Inert gas is filled for protection, and a uniform pressure of 0.5 MPa is applied. The pressure is transmitted to the surface of the yttrium oxide ceramic bushing through a fluid medium, so that the yttrium oxide ceramic bushing and the first protective film can make surface contact.
[0065] 4. Pressure holding and curing: Maintain pressure for 10 minutes and then slowly release the pressure.
[0066] The interface contact gap was tested to be <1μm.
[0067] Yttrium oxide ceramics effectively block the electric field from escaping from the edge of helium gas pores due to their high resistivity and low secondary electron emission coefficient.
[0068] Step 3: Bushing edge sealing and integrated encapsulation A 0.5mm deep annular groove is machined on the chuck substrate around the yttrium oxide ceramic bushing, and a high-temperature resistant and radiation-resistant perfluoroether rubber (FFKM) sealing ring is embedded to keep the perfluoroether rubber sealing ring in a compressed state with the deformation controlled at 20%.
[0069] Regarding the dimensions of the perfluoroelastomer (PF) rubber seal: The PF rubber seal forms an interference fit with a 0.5mm deep annular groove. The cross-sectional diameter (wire diameter) of the PF rubber seal is designed to be 0.625mm, making it larger than the groove depth, thus generating compression deformation during assembly and tightening. This dimensional fit is crucial for generating sufficient springback preload, ensuring reliable sealing and preventing gas leakage under dynamic conditions such as high temperature and vacuum.
[0070] The electrostatic chuck flange is locked to the reaction chamber base flange by bolt assembly, and axial clamping force is applied to cause the perfluoroether rubber seal ring to undergo 20% compression deformation, ensuring good resilience and sealing reliability even in vacuum and high temperature (up to 200°C) environments.
[0071] This edge sealing structure completely blocks the path of process gas to penetrate into the internal helium channel and electrode area, preventing the formation of conductive pathways due to gas ionization.
[0072] An electrostatic chuck assembly with a protective structure was obtained.
[0073] Performance testing and verification: (1) Surface morphology analysis of the first protective film: The surface of the electrostatic chuck substrate on which the first protective film was deposited was observed by scanning electron microscopy (SEM). The SEM images are referenced from [reference]. Figure 1 .
[0074] The results showed that the coating surface was dense and free of pinhole defects, and the microstructure exhibited excellent uniformity and smoothness.
[0075] Further, atomic force microscopy (AFM) was used to test the nanoscale roughness of the coating surface, and the test results were referenced. Figure 2-4 .
[0076] Within a 5μm × 5μm scanning area, the root mean square roughness (RMS) of the surface was measured to be 0.988nm. This test result directly demonstrates that the ALD process successfully constructed an atomically smooth interface, effectively eliminating microscopic protrusions and depressions on the substrate surface, and creating ideal physical conditions for the subsequent tight bonding of the yttrium oxide ceramic bushing.
[0077] (2) Interface bonding state: Based on the extremely low surface roughness (Ra is only 0.988 nm), when the yttrium oxide ceramic liner is fitted onto the smooth interface of the first protective film, the two can achieve a large-area tight bond. This nanoscale surface contact will significantly increase the interface bonding energy, effectively avoiding the risk of interlayer delamination or peeling caused by local gaps, thereby ensuring the mechanical stability of the multilayer protective structure under complex working conditions.
[0078] (3) Discharge suppression mechanism: Since the first protective film is not only smooth but also completely covers the inner wall of the helium hole, it acts as the first line of defense and can effectively block the concentrated emission of the electric field at the edge of the hole wall. Combined with the yttrium oxide ceramic bushing (high resistivity material) and fluororubber edge sealing structure assembled later, this composite design physically isolates the plasma penetration path into the helium hole.
[0079] The protective structure provided in this application can effectively suppress abnormal discharge of the helium gas hole in the electrostatic chuck, thereby preventing damage to the back of the substrate due to ion bombardment.
[0080] It should be understood that the application of this application is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of this application.
Claims
1. A method for preparing a protective structure to suppress abnormal discharge of helium gas orifice in an electrostatic chuck, characterized in that, Includes the following steps: A first protective film is deposited on the surface of an electrostatic chuck substrate; the surface roughness of the first protective film Ra < 3 nm; A yttrium oxide ceramic bushing is placed in the helium pore area on the surface of the electrostatic chuck substrate, and vacuum-assisted pressing technology is used to make the yttrium oxide ceramic bushing tightly bonded to the first protective film, with an interface contact gap of <1μm. A fluororubber sealing ring is used to seal the joint area between the edge of the yttrium oxide ceramic bushing and the electrostatic chuck substrate.
2. The method for preparing the protective structure for suppressing abnormal discharge of the helium gas orifice in an electrostatic chuck according to claim 1, characterized in that, The first protective film includes one or more of the following: aluminum oxide film, titanium nitride film, and titanium oxide film; The thickness of the first protective film is 1-100 nm.
3. The method for preparing the protective structure for suppressing abnormal discharge of the helium gas orifice in an electrostatic chuck according to claim 1, characterized in that, The vacuum-assisted pressing technology includes: The electrostatic chuck substrate and the yttrium oxide ceramic bushing on which the first protective film is deposited are subjected to vacuum degassing; In a vacuum environment, the yttrium oxide ceramic bushing is placed on the surface of the electrostatic chuck substrate in the area corresponding to the helium gas hole, but the yttrium oxide ceramic bushing does not cover the helium gas hole; Inert gas is introduced for protection, and a uniform pressure of 0.1-1 MPa is applied to make the yttrium oxide ceramic bushing in surface contact with the first protective film. Maintain pressure for 5-20 minutes, then release the pressure.
4. The method for preparing the protective structure for suppressing abnormal discharge of the helium gas orifice in an electrostatic chuck according to claim 1, characterized in that, The sealing treatment of the joint area between the edge of the yttrium oxide ceramic bushing and the electrostatic chuck substrate using a fluororubber sealing ring includes: The yttrium oxide ceramic bushing has an annular groove around its periphery, into which the fluororubber sealing ring is embedded, so that the fluororubber sealing ring is in a compressed state with a deformation of 15%-30%.
5. The method for preparing the protective structure for suppressing abnormal discharge of the helium gas orifice in an electrostatic chuck according to claim 1, characterized in that, When the first protective film is an alumina film, the process includes the following steps: controlling the chamber temperature to 150℃-200℃, the flow rate to 50sccm-500sccm, and the chamber pressure to 0.1Torr-10Torr; the precursor pulse time to 0.1 seconds-2 seconds; introducing aluminum source precursor and oxidant, and cyclically depositing to form the alumina film.
6. The method for preparing the protective structure for suppressing abnormal discharge of the helium gas orifice in an electrostatic chuck according to claim 5, characterized in that, The aluminum source precursor includes trimethylaluminum, and the oxidant includes one or a mixture of two of H2O and O3.
7. The method for preparing the protective structure for suppressing abnormal discharge of the helium gas orifice in an electrostatic chuck according to claim 1, characterized in that, Before depositing the first protective film on the surface of the electrostatic chuck substrate, the surface of the electrostatic chuck substrate is subjected to plasma cleaning and activation treatment.
8. The method for preparing the protective structure for suppressing abnormal discharge of the helium gas orifice in an electrostatic chuck according to claim 1, characterized in that, The thickness of the yttrium oxide ceramic bushing is 0.5-2 mm.
9. A protective structure for suppressing abnormal discharge of helium gas holes in an electrostatic chuck, prepared by the method for preparing a protective structure for suppressing abnormal discharge of helium gas holes in an electrostatic chuck according to any one of claims 1-8, is disposed on the surface of an electrostatic chuck substrate, characterized in that, The protective structure includes a first protective film, a yttrium oxide ceramic bushing, and a fluororubber sealing ring; The first protective film is deposited on the surface of the electrostatic chuck substrate; The yttrium oxide ceramic bushing is embedded in the surface of the electrostatic chuck substrate on which the first protective film is deposited, and the yttrium oxide ceramic bushing is placed in the area of the electrostatic chuck substrate surface corresponding to the helium gas hole. The yttrium oxide ceramic bushing has an annular groove on its outer periphery, and the fluororubber sealing ring is fixedly connected to the yttrium oxide ceramic bushing at the corresponding annular groove.
10. The protective structure for suppressing abnormal discharge of the helium gas port of an electrostatic chuck according to claim 9, characterized in that, The depth of the annular groove is 70%-90% of the cross-sectional diameter of the fluororubber sealing ring.