Electrostatic chuck surface structure and forming method thereof

Abstract

The invention relates to a surface structure of an electrostatic chuck used in a semiconductor manufacturing process. The surface structure includes a substrate, a first protective coating disposed on the substrate, and a second protective coating disposed on the first protective coating. The first protective coating is deposited on the substrate and is made of a material selected from the group consisting of metal oxides, fluorides and nitrides. As a universal protective screen, the protective screen is resistant to abrasion, corrosion and heat effect. The second protective coating is deposited on the first protective coating having a hardness higher than that of the first protective coating, providing enhanced wear resistance. In addition, the invention also provides a multifunctional and effective solution, which is used for improving the performance and prolonging the service life of the electrostatic chuck in semiconductor manufacturing.

Description

Technical Field

[0001] The present invention generally relates to the field of semiconductor manufacturing equipment, and more particularly, to a surface structure of an improved electrostatic chuck (ESC) for a semiconductor process chamber and a method for forming the same. Background Art

[0002] In the manufacturing process of semiconductor wafers, electrostatic chucks are widely used in various process chambers to hold the wafers during operations such as heating, adsorption, and rotation. These chucks usually employ surface treatments to improve their performance and durability.

[0003] A common surface treatment method is thermal spraying. However, with the advancement of semiconductor manufacturing technology, the requirements for the surface treatment of electrostatic chucks have become increasingly stringent, and traditional thermal spraying techniques often result in insufficient density and hardness of the coating. This is a significant drawback. In addition, since the frequent loading and unloading of wafers may cause the bumps of the chuck to wear, this wear may in turn cause particulate matter to adhere to the back of the wafer, thereby affecting the yield of subsequent processes.

[0004] Another common surface treatment method is preparation using sintering technology. Although sintered electrostatic chucks can provide higher hardness, the overall manufacturing cost of the electrostatic chucks also increases significantly.

[0005] Therefore, how to design an electrostatic chuck whose surface structure has high hardness, high density, and wear resistance, and at the same time is cost-effective, is a problem worthy of consideration for those with ordinary knowledge in the art. Summary of the Invention

[0006] The object of the present invention is to provide a surface structure of an electrostatic chuck, which has high hardness, high density, and wear resistance, and at the same time has a relatively low manufacturing cost.

[0007] The present invention solves the limitations and challenges of electrostatic chucks (ESC) used in traditional semiconductor manufacturing, and introduces an innovative surface structure. This surface structure includes a substrate, a first protective coating disposed on the substrate, and a second protective coating disposed on the first protective coating. The hardness of the second protective coating is higher than that of the first protective coating, thereby providing enhanced wear resistance.

[0008] The present invention is further distinguished in that the porosity of the second protective coating is less than the porosity of the first protective coating. This characteristic ensures higher density and helps to improve the overall durability and performance of the electrostatic chuck. The first protective coating is selected from the group consisting of metal oxides, fluorides, and nitrides, and its thickness is between 100 μm and 250 μm. This layer serves as a solid base, protecting the underlying substrate and improving the overall wear resistance and corrosion resistance of the ESC.

[0009] The second protective coating is also selected from the group consisting of metal oxides, fluorides, and nitrides, but it has a smaller thickness, ranging from 0.5 μm to 20 μm. Despite its thinness, this layer provides extremely high hardness, ranging from 1000 HV to 1500 HV, and a porosity of less than 1%. These properties make it very effective in reducing particle contamination from the chuck to the wafer, thereby improving the yield of subsequent semiconductor manufacturing processes.

[0010] In addition to the structural characteristics, another object of the present invention is to provide a method for forming the surface structure of the electrostatic chuck.

[0011] The method for forming the surface structure of the electrostatic chuck includes forming a first protective coating on a substrate, then forming a second protective coating on the first protective coating, and optimizing specific deposition conditions for each layer to achieve the desired properties.

[0012] By providing a combination of high hardness, low porosity, and wear resistance, and in a cost-effective manner, the present invention significantly advances the state of the art of electrostatic chuck technology in semiconductor manufacturing.

[0013] The present invention has the following advantages: it has high hardness, high density, and wear resistance, and at the same time can reduce the cost of manufacturing the surface structure of the electrostatic chuck.

[0014] To make the above features and advantages of the present invention more obvious and understandable, the following preferred embodiments are specifically described below in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram of the surface structure 10 of the electrostatic chuck of this embodiment is shown.

[0016] Figure 2 A flowchart of the method for forming the surface structure 10 of the electrostatic chuck is shown. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Please refer to Figure 1 , Figure 1 A schematic diagram of the surface structure 10 of the electrostatic chuck of this embodiment is shown. The present invention provides a surface structure of an advanced electrostatic chuck (ESC), and its unique surface structure design is used to meet the strict requirements of modern semiconductor manufacturing processes. The surface structure 10 of the electrostatic chuck of this embodiment consists of three main components: a substrate 12, a first protective coating 13, and a second protective coating 14.

[0018] The substrate 12 is usually made of a conductive or semiconductor material that can generate an electrostatic field, which fixes the semiconductor wafer in place during various manufacturing processes. In this embodiment, the substrate 12 can be made of aluminum, silicon, or other metals and ceramic materials commonly used in the industry.

[0019] The substrate 12 is a fundamental element of the electrostatic chuck and plays a crucial role in the overall performance and functionality of the electrostatic chuck. Usually, a protective layer is deposited on the substrate 12, and the substrate 12 is responsible for generating the electrostatic field that holds the semiconductor wafer in place during the manufacturing process.

[0020] In this embodiment, several factors need to be considered when selecting the material of the substrate 12. First of all, the material must be conductive or semiconductive to generate a sufficient electrostatic field. Common materials include aluminum, silicon, and other metals or ceramics compatible with the semiconductor manufacturing environment. The material should also have high thermal conductivity to uniformly heat the wafer, thereby ensuring the consistency of the manufacturing process.

[0021] In addition, the structural integrity of the substrate 12 is another important consideration. It must be strong enough to withstand the mechanical stress generated during wafer loading and unloading, as well as the thermal stress generated during wafer heating. And, the substrate 12 is usually designed with a specific geometry to optimize its mechanical properties, such as tensile strength and fracture toughness.

[0022] In addition, usually before depositing the protective layer, the substrate 12 will go through a series of surface preparation steps. These may include cleaning, etching, and priming to ensure the surface is free of contaminants and conducive to the adhesion of subsequent layers. The surface roughness of the substrate 12 may also be controlled within a specific range to optimize the bonding strength between the substrate 12 and the first protective coating 13.

[0023] The electrical properties of the substrate 12, such as resistivity and dielectric constant, are also adjusted to optimize the electrostatic holding force. These properties are particularly important when dealing with extremely thin or irregularly shaped wafers, as they ensure that the wafer is firmly held in place throughout the manufacturing process.

[0024] Please refer to again Figure 1 , the first protective coating 13 is directly disposed on the surface of the substrate 12, and the first protective coating 13 is used to protect the substrate 12 from wear and corrosion, thereby extending the service life of the electrostatic chuck (ESC).

[0025] In this embodiment, the first protective coating 13 is formed using thermal spraying techniques, such as atmospheric plasma spraying (APS), suspension plasma spraying (SPS), or vacuum plasma spraying (VPS). Each method has its own advantages and limitations, and the choice of which method usually depends on factors such as the required coating thickness, porosity, and hardness. The thickness range of the first protective coating 13 is from 100 μm to 250 μm. This range is to provide sufficient protection to the substrate 12 while also allowing effective heat conduction.

[0026] The material of the first protective coating 13 is selected from the group consisting of metal oxides, fluorides, and nitrides, such as TiO2 , Al 2 O 3 , YF 3 , Er 2 O 3 , Gd 2 O 3 , Y 2 O 3 etc. These materials are well-known for their excellent thermal stability, corrosion resistance, and mechanical properties, making them an ideal choice for this application.

[0027] The hardness of the first protective coating 13 is designed to be in the range of 400 HV to 700 HV, providing a balance between mechanical strength and flexibility.

[0028] Since the first protective coating 13 requires a relatively thick thickness, a thermal spraying technique is adopted to increase its deposition rate. Along with different process designs, its porosity ranges from 1% to 5%.

[0029] The deposition process is carefully controlled to achieve the desired properties of the first protective coating 13. For example, an arc current from 200 A to 600 A and a turntable speed from 5 RPM to 30 RPM can be used. The choice of carrier gas, such as argon, nitrogen, or helium, and its flow rate are also optimized to ensure high-quality deposition.

[0030] By carefully designing and implementing the first protective coating 13, the present invention significantly improves the performance and lifespan of the electrostatic chuck. The first protective coating 13 has sufficient thickness and strength to increase the wear and corrosion resistance of the substrate.

[0031] Please refer to Figure 1 again. The second protective coating 14 is disposed on top of the first protective coating 13. The second protective coating 14 is much thinner than the first layer, with a thickness ranging from 0.5 μm to 20 μm. Although the second protective coating 14 is thin, this layer provides extremely high hardness, ranging from 1000 HV to 1500 HV, thereby providing better wear resistance and reducing the risk of particle contamination.

[0032] The second protective coating 14 is formed using physical vapor deposition (PVD) technology to make the second protective coating 14 form a high-density and high-hardness coating. Specifically, the physical vapor deposition process is highly controlled to achieve the desired properties of the second protective coating 14. For example, parameters such as chamber temperature, deposition rate, ion source plasma power, and gas flow rate are finely adjusted. For example, the chamber temperature may range from 25 °C to 200 °C, the deposition rate from 0.1 nm / s to 1.5 nm / s, and other parameters.

[0033] In addition, the method of physical vapor deposition (PVD) is, for example, electron beam physical vapor deposition (E-Gun PVD) or ion-assisted electron beam physical vapor deposition, and each method provides specific advantages in terms of coating quality and process control.

[0034] Although the material of the second protective coating 14 is also selected from the group consisting of metal oxides, fluorides, and nitrides, similar to the first protective coating 13. However, due to the use of vacuum physical vapor deposition technology, a protective coating with higher hardness and lower porosity can be produced. The porosity of the second protective coating 14 is designed to be less than 1%, which is significantly lower than that of the first protective coating 13. This low porosity helps to improve the hardness and wear resistance of the second protective coating 14, making it an ideal choice for long-term contact with semiconductor wafers and being very effective in reducing particle contamination from the chuck to the wafer.

[0035] In summary, the second protective coating 14, as the topmost layer, directly contacts the semiconductor wafer, providing extremely high hardness, low porosity, and excellent wear resistance, thereby enhancing the corrosion resistance and wear resistance of the first protective coating 13. Therefore, the electrostatic chuck surface structure 10 of this embodiment solves the disadvantages of existing electrostatic chucks. It not only enhances wear resistance but also significantly reduces the risk of particle contamination, reduces the overall manufacturing cost, and thus improves the yield and reliability of the semiconductor manufacturing process.

[0036] Please refer to Figure 2 , Figure 2 which shows a flowchart of the method for forming the electrostatic chuck surface structure 10. Hereinafter, a detailed description will be given of how to manufacture the electrostatic chuck surface structure 10 of this embodiment.

[0037] First, please refer to step S1. The first protective coating 13 is deposited on the substrate 12 using thermal spraying technology under specific conditions, such as atmospheric plasma spraying (APS), suspension plasma spraying (SPS), and vacuum plasma spraying (VPS). The details of the three thermal spraying technologies are as follows:

[0038] 1. Atmospheric plasma spraying (APS) is one of the most commonly used technologies for depositing the first protective coating 13. In this method, the coating material is fed into a high-temperature plasma jet, which pushes the molten particles towards the substrate 12. APS is usually carried out at atmospheric pressure and is applicable to a wide range of materials, including metal oxides, fluorides, and nitrides. Process parameters such as arc current (200A - 600A), carrier gas flow rate (30L / min - 200L / min), and turntable speed (5RPM - 30RPM) can be adjusted to achieve the desired coating properties.

[0039] II. Suspension Plasma Spraying (SPS) is a variant of conventional plasma spraying but uses a suspension of fine powder particles in a liquid medium. This method allows for the deposition of layers with unique microstructures and enhanced properties. SPS is particularly suitable for depositing coatings with complex compositions, such as mixed oxides. The process conditions are similar to APS, but additional control may be required to manage the supply rate of the suspension and plasma parameters.

[0040] III. Vacuum Plasma Spraying (VPS) is carried out in a controlled vacuum environment, which minimizes oxidation and contamination during the spraying process. This method is very suitable for materials sensitive to atmospheric conditions. VPS allows for more stringent control of the microstructure and properties of the coating. The vacuum pressure during the process ranges from 5.0E1 to 1.0E-2 Torr, and the preheating temperature can be set between 100°C and 300°C to improve the adhesion of the coating.

[0041] Also, the plasma spraying deposition process is controlled by several parameters to achieve the desired coating properties. These include an arc current ranging from 200 A to 600 A, a substrate rotation speed ranging from 5 RPM to 30 RPM, and the type of carrier gas such as argon, nitrogen, or helium. Also, the gas flow rate is adjusted between 30 L / min and 200 L / min, and the process pressure may vary from 1 atmosphere to 1.0E-2 Torr. The ion spraying technique is very suitable for depositing thick coatings in the range of 100 μm to 250 μm, thus providing strong protection for the metal components of the electrostatic chuck.

[0042] In addition, an optional but usually beneficial step in the process is the preheating of the substrate 12. Among them, the preheating temperature of the substrate 12 can range from 100°C to 3000°C, which helps to improve the adhesion and density of the deposited layer. Also, when the thermal properties of the material of the substrate 12 are different from those of the coating material, the step of preheating the substrate 12 is extremely helpful for the adhesion between the substrate 12 and the first protective coating 13.

[0043] After that, referring to step S2, a second protective coating 14 is deposited on the first protective coating 13 using Physical Vapor Deposition (PVD) technology under optimized conditions. Among them, the Physical Vapor Deposition (PVD) technology is, for example, Electron Beam Physical Vapor Deposition (E-Gun PVD) or Ion-Assisted Electron Beam Physical Vapor Deposition, and the details of these two Physical Vapor Depositions are described as follows:

[0044] I. Electron Beam Physical Vapor Deposition (E-Gun PVD) is a highly specialized thin film deposition method. In this technique, an electron beam is used to evaporate source materials, which then condense on the substrate 12 to form a coating. The process is carried out in a high vacuum chamber, allowing precise control over the microstructure and properties of the film. The deposition conditions can be finely adjusted, including the chamber temperature (25°C to 200°C), deposition rate (0.1 nm / s to 1.5 nm / s), and process pressure (1.0E-2 to 1.0E-6 Torr). This method is particularly suitable for depositing coatings with high hardness (1000 - 1500 HV) and low porosity (<1%).

[0045] II. Ion-Assisted Electron Beam Physical Vapor Deposition, which is an advanced variant of E-Gun PVD, where an ion source is used to assist the deposition process. Ion assistance helps improve the density, adhesion, and other mechanical properties of the film. Ion source parameters such as plasma power, electron beam current (0 - 1500 mA), and voltage (100 V - 1500 V) can be adjusted to achieve the desired coating characteristics. The gas flow rates of argon and oxygen can be adjusted in the range of 5 sccm to 50 sccm and 10 sccm to 200 sccm.

[0046] Among them, both Electron Beam Physical Vapor Deposition (E-Gun PVD) and Ion-Assisted Electron Beam Physical Vapor Deposition are very suitable for depositing a second protective coating 14 composed of metal oxides, fluorides, or nitrides, with a thickness range from 0.5 microns to 20 microns.

[0047] In addition, the above optimization conditions include chamber temperature, deposition rate, and process pressure. For example, chamber temperature (25°C to 200°C), deposition rate (0.1 nm / s to 1.5 nm / s), and ion source plasma power. Also, the electron beam current can range from 0 to 1500 mA, and the voltage from 100 V to 1500 V.

[0048] Furthermore, carrier gases such as argon and oxygen used in Physical Vapor Deposition (PVD) technology have a flow rate range from 5 sccm to 50 sccm and 10 sccm to 200 sccm, and the process pressure is maintained between 1.0E-2 and 1.0E-6 Torr. Through the deposition method, materials, and process parameters under optimized conditions, a second protective coating 14 with superior properties that exceed the strict requirements of semiconductor manufacturing is formed, which can greatly improve performance and extend the life of the electrostatic chuck.

[0049] Therefore, compared with the traditional method of forming the surface structure of the electrostatic chuck using the sintering method, this method chooses to use thermal spraying technology and physical vapor deposition methods to generate the first protective coating 13 and the second protective coating 14, which can more effectively reduce the cost of manufacturing the surface structure 10 of the electrostatic chuck.

[0050] In summary, the present invention provides a surface structure of an electrostatic chuck and a method for forming the same, which not only meets the performance and durability requirements of contemporary semiconductor manufacturing processes, but also exceeds these requirements. Therefore, the present invention represents a significant advancement in this field, providing a combination of high hardness, low porosity, and excellent wear resistance in a cost-effective manner.

[0051] Although the present invention has been disclosed above in preferred embodiments, it is not intended to limit the present invention. Any person with ordinary knowledge in the relevant technical field may make some modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the scope of the appended patent application.

Claims

1. An electrostatic chuck surface structure, characterized in that: include: a substrate; a first protective coating disposed on a surface of the substrate; and a second protective coating disposed on the first protective coating; Wherein, the hardness of the second protective coating layer is greater than that of the first protective coating layer, and the porosity of the second protective coating layer is less than 1%.

2. The electrostatic chuck surface structure according to claim 1, characterized in that: The porosity of the second protective coating layer is less than the porosity of the first protective coating layer.

3. The electrostatic chuck surface structure according to claim 1, characterized in that: The first protective coating layer is selected from the group consisting of metal oxides, fluorides and nitrides, and the thickness of the first protective coating layer is between 100 μm and 250 μm.

4. The electrostatic chuck surface structure according to claim 1, characterized in that: The hardness of the first protective coating is between 400 HV and 700 HV.

5. The electrostatic chuck surface structure according to claim 1, wherein: The porosity of the first protective coating is between 1% and 5%.

6. The electrostatic chuck surface structure according to claim 1, wherein: The second protective coating layer is selected from the group consisting of metal oxides, fluorides and nitrides, and the thickness of the second protective coating layer is between 0.5 μm and 20 μm.

7. The electrostatic chuck surface structure according to claim 1, characterized in that: The hardness of the second protective coating is between 1000 HV and 1500 HV.

8. A method for forming a surface structure of an electrostatic chuck, characterized in that: include: Forming a first protective coating on a surface of a substrate; and forming a second protective coating on the first protective coating; Wherein, the hardness of the second protective coating layer is greater than the hardness of the first protective coating layer, and the porosity of the second protective coating layer is less than 1%.

9. The method for forming a surface structure of an electrostatic chuck according to claim 8, wherein: Further including: Prior to forming the first protective coating, the substrate is preheated to a temperature between 100°C and 300°C.

10. The method for forming a surface structure of an electrostatic chuck according to claim 8, wherein: The first protective coating is deposited by using the following methods: atmospheric plasma spraying, suspension plasma spraying or vacuum plasma spraying.

11. The method for forming a surface structure of an electrostatic chuck according to claim 10, wherein: The deposition conditions of the first protective coating are selected from the group consisting of: The arc current is between 200A and 600A, the turntable speed is between 5RPM and 30RPM, the carrier gas type is selected from argon, nitrogen and helium, and the gas flow rate is between 30L / min and 200L / min.

12. The method for forming a surface structure of an electrostatic chuck according to claim 8, wherein: The second protective coating is deposited using the following methods: electron beam physical vapor deposition (E-Gun PVD) or ion-assisted electron beam physical vapor deposition.

13. The method for forming a surface structure of an electrostatic chuck according to claim 12, wherein: The deposition conditions of the second protective coating are selected from the group consisting of: The chamber temperature is between 25°C and 200°C, the deposition rate is between 0.1nm / s and 1.5nm / s, the ion source plasma power assist electron beam current is between 0mA and 1500mA, the voltage is between 100V and 1500V, the gas flow rate of argon is between 5sccm and 50sccm, the gas flow rate of oxygen is between 10sccm and 200sccm, and the process pressure is between 1.0E-2 and 1.0E-6Torr.

14. The method for forming a surface structure of an electrostatic chuck according to claim 8, wherein: The porosity of the second protective coating layer is less than the porosity of the first protective coating layer.

15. The method for forming a surface structure of an electrostatic chuck according to claim 8, wherein: The first protective coating layer is selected from the group consisting of metal oxides, fluorides and nitrides, and the thickness of the first protective coating layer is between 100 μm and 250 μm.

16. The method for forming a surface structure of an electrostatic chuck according to claim 8 or claim 15, characterized in that: The hardness of the first protective coating is between 400 HV and 700 HV.

17. The method for forming a surface structure of an electrostatic chuck according to claim 8 or claim 15, characterized in that: The porosity of the first protective coating is between 1% and 5%.

18. The method for forming a surface structure of an electrostatic chuck according to claim 8, wherein: The second protective coating layer is selected from the group consisting of metal oxides, fluorides and nitrides, and the thickness of the second protective coating layer is between 0.5 μm and 20 μm.

19. The method for forming a surface structure of an electrostatic chuck according to claim 8 or claim 18, characterized in that: The hardness of the second protective coating is between 1000 HV and 1500 HV.

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