Surface structure of an electrostatic chuck and method for manufacturing the same

Abstract

To provide the surface structure of an electrostatic chuck with a large hardness, a high density, and a high resistance to wearing, the surface structure being manufactured at a lower cost and used in the manufacturing step of a semiconductor, and to provide a method for manufacturing the surface structure of an electrostatic chuck.SOLUTION: The surface structure of an electrostatic chuck includes: a base material; a first protective coating layer on the base material; and a second protective coating layer on the first protective coating layer. The first protective coating layer is a material selected from the group of metal oxide, fluoride, and nitride, is deposited on the bae material, functions as a general protective barrier, and is resistant to wearing, corrosion, and heat. The second protective coating layer is deposited on the first protective coating layer, has a larger hardness than the first protective coating layer, and realizes a reinforced resistance to wearing. The base material is designed to have a specific geometric shape to optimize mechanical performances including the tensile strength or the fracture toughness.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention generally relates to the field of semiconductor manufacturing equipment, and more specifically, to the surface structure of an improved electrostatic chuck (ESC) used in a semiconductor process chamber.

Background Art

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

[0003] One common surface treatment method is thermal spraying. However, with the advancement of semiconductor manufacturing technology, the surface treatment requirements for electrostatic chucks have become increasingly stringent, and conventional thermal spraying technology often tends to have insufficient coating density and hardness. This is a significant drawback. Furthermore, frequent loading and unloading of wafers may cause wear of the protruding parts of the chuck, and this wear may in turn cause particulate matter to adhere to the back surface of the wafer, potentially affecting the yield of subsequent processes.

[0004] Another common surface treatment method is to use sintering technology. Sintered electrostatic chucks can provide higher hardness, but the manufacturing cost of the entire electrostatic chuck also increases significantly. Therefore, a method for designing an electrostatic chuck with high hardness, high density, wear resistance, and high cost-effectiveness is an issue to be considered by those skilled in the art.

Summary of the Invention

Problems to be Solved by the Invention

[0005] An object of the present invention is to provide a surface structure of an electrostatic chuck having high hardness, high density, wear resistance, and low manufacturing cost.

[0006] This invention solves the limitations and problems of conventional electrostatic chucks (ESCs) used in semiconductor manufacturing and introduces an innovative surface structure. The surface structure includes a substrate, a first protective coating layer provided on the substrate, and a second protective coating layer provided on the first protective coating layer. The hardness of the second protective coating layer is higher than that of the first protective coating layer, thereby providing enhanced wear resistance.

[0007] The present invention is further characterized in that the porosity of the second protective coating layer is smaller than that of the first protective coating layer. This property ensures a higher density and helps improve the overall durability and performance of the electrostatic chuck. The first protective coating layer is selected from the group consisting of metal oxides, fluorides, and nitrides, and its thickness ranges from 100 μm to 250 μm. This layer acts as a robust base, protecting the underlying substrate and improving the overall wear resistance and corrosion resistance of the ESC.

[0008] The second protective coating layer is also selected from the group consisting of metal oxides, fluorides, and nitrides, but its thickness is thinner, ranging from 0.5 μm to 20 μm. Despite its thinness, the layer provides ultra-high hardness in the range of 1000 HV to 1500 HV and a porosity of less than 1%. These properties make it highly effective in reducing particle contamination from the chuck to the wafer, thereby improving the yield of subsequent semiconductor processes. In addition to structural properties, another object of the present invention is to provide a method for forming the surface structure of the electrostatic chuck.

[0009] A method for forming the surface structure of an electrostatic chuck includes forming a first protective coating layer on a substrate, then forming a second protective coating layer on the first protective coating layer, and optimizing specific deposition conditions to achieve desired properties for each layer.

[0010] By providing a cost-effective combination of high hardness, low porosity, and wear resistance, this invention significantly advances the current state of electrostatic chuck technology in semiconductor manufacturing. Specifically, this invention has the following advantages: it provides high hardness, high density, and wear resistance, while also reducing the manufacturing cost of the surface structure of the electrostatic chuck.

[0011] To better understand the above-mentioned features and advantages of the present invention, preferred embodiments are given below and described in detail with reference to the accompanying drawings. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic diagram of the surface structure 10 of the electrostatic chuck according to this embodiment of the present invention. [Figure 2] This is a flowchart of the method for forming the surface structure 10 of the electrostatic chuck. [Modes for carrying out the invention]

[0013] The explanation will be given with reference to Figure 1. Figure 1 shows a schematic diagram of the electrostatic chuck surface structure 10 of this embodiment. The present invention provides an advanced electrostatic chuck (ESC) surface structure having a unique surface structure designed to meet the stringent requirements of modern semiconductor manufacturing processes. The electrostatic chuck surface structure 10 of this embodiment mainly consists of three components: a substrate 12, a first protective coating layer 13, and a second protective coating layer 14.

[0014] The substrate 12 is typically manufactured from a conductive or semiconductor material and can generate an electrostatic field. This electrostatic field plays a role in fixing the semiconductor wafer in various manufacturing processes. In this embodiment, the substrate 12 can be manufactured from aluminum, silicon, or other metal and ceramic materials commonly used in the industry.

[0015] The substrate 12 is the base element of the electrostatic chuck and plays a crucial role in the overall performance and function of the electrostatic chuck. Typically, 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.

[0016] In this embodiment, the following factors are considered in selecting the material for the substrate 12. First, the material must be conductive or semiconducting in order to generate a sufficient electrostatic field. Common materials include aluminum, silicon, and other metals or ceramics compatible with semiconductor manufacturing environments. Furthermore, the material must have high thermal conductivity to ensure process consistency by uniformly heating the wafer.

[0017] Furthermore, the structural integrity of the substrate 12 is also an important consideration. The substrate 12 must have sufficient strength to withstand the mechanical stresses that occur during wafer loading and unloading, as well as the thermal stresses that occur during wafer heating. In addition, the substrate 12 is usually designed with a specific geometric shape to optimize mechanical properties such as tensile strength and fracture toughness.

[0018] In addition, the substrate 12 typically undergoes a series of surface preparation steps before the protective layer is deposited. These may include cleaning, etching, and priming to remove surface contaminants and promote adhesion of subsequent layers. The surface roughness of the substrate 12 is also controlled within a specific range to optimize the adhesion strength between the substrate 12 and the first protective coating layer 13.

[0019] The electrical properties of the substrate 12, such as resistivity and dielectric constant, are also adjusted to optimize the electrostatic coercivity. These properties are particularly important when dealing with extremely thin or irregularly shaped wafers, ensuring that the wafer is securely fixed throughout the manufacturing process.

[0020] Let's explain again with reference to Figure 1. The first protective coating layer 13 is directly applied to the surface of the substrate 12 and plays a role in extending the service life of the electrostatic chuck (ESC) by protecting the substrate 12 from wear and corrosion.

[0021] In this embodiment, the first protective coating layer 13 is formed using a thermal spraying technique. For example, atmospheric plasma spraying (APS), suspension plasma spraying (SPS), or vacuum plasma spraying (VPS) is used. Each method has its own advantages and limitations, and the method selected usually depends on factors such as the required coating thickness, porosity, and hardness. The thickness range of the first protective coating layer 13 is from 100 μm to 250 μm. This range is set to provide sufficient protection to the substrate 12 while enabling effective heat conduction.

[0022] The material of the first protective coating layer 13 is selected from the group consisting of metal oxides, fluorides, and nitrides, and examples include TiO2, Al2O3, YF3, Er2O3, Gd2O3, Y2O3, etc. These materials are known for their excellent thermal stability, corrosion resistance, and mechanical properties, and are the optimal choice for this application.

[0023] The hardness of the first protective coating layer 13 is designed to be in the range of 400 HV to 700 HV, providing a balance between mechanical strength and flexibility.

[0024] Since the first protective coating layer 13 requires a relatively thick thickness, a thermal spraying technique is adopted to increase its deposition rate. With different process designs, its porosity is in the range of 1% to 5%.

[0025] The deposition process is carefully controlled to achieve the desired properties of the first protective coating layer 13. For example, an arc current of 200 A to 600 A and a turntable speed of 5 RPM to 30 RPM can be used. The selection of the carrier gas (argon, nitrogen, helium) and its flow rate are also optimized to ensure high-quality deposition.

[0026] By carefully designing and implementing the first protective coating layer 13, the present invention has significantly improved the performance and lifespan of the electrostatic chuck. The first protective coating layer 13 has sufficient thickness and strength, enhancing the wear resistance and corrosion resistance of the substrate.

[0027] Referring back to FIG. 1 for explanation. The second protective coating layer 14 is provided on top of the first protective coating layer 13. The second protective coating layer 14 is much thinner than the first layer, with a thickness ranging from 0.5 μm to 20 μm. Despite its thin thickness, the second protective coating layer 14 provides an ultra-high hardness of 1000 HV to 1500 HV, thereby resulting in excellent wear resistance and reducing the risk of particle contamination.

[0028] The second protective coating layer 14 is formed using physical vapor deposition (PVD) technology to achieve 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 layer 14. For example, parameters such as chamber temperature, deposition rate, ion source plasma power, and gas flow rate are precisely adjusted. The chamber temperature ranges from 25 °C to 200 °C, and the deposition rate is, for example, from 0.1 nm / s to 1.5 nm / s.

[0029] Furthermore, as methods of physical vapor deposition (PVD), there are electron beam physical vapor deposition (E-Gun PVD) and ion-assisted electron beam physical vapor deposition, each providing specific advantages in coating quality and process control.

[0030] The material for the second protective coating layer 14 is also selected from the group consisting of metal oxides, fluorides, and nitrides, similar to the first protective coating layer 13. However, by employing vacuum physical deposition technology, a protective coating with higher hardness and lower porosity can be produced. The porosity of the second protective coating layer 14 is designed to be less than 1%, which is significantly lower than that of the first protective coating layer 13. This low porosity improves the hardness and wear resistance of the second protective coating layer 14, making it ideal for long-term contact with semiconductor wafers and highly effective in reducing particle contamination from the chuck to the wafer.

[0031] As described above, the second protective coating layer 14, as the uppermost layer, directly contacts the semiconductor wafer, providing ultra-high hardness, low porosity, and excellent wear resistance, improving the corrosion resistance and wear resistance of the first protective coating layer 13. Therefore, the electrostatic chuck surface structure 10 of this embodiment solves the shortcomings of conventional electrostatic chucks, not only enhancing wear resistance but also significantly reducing the risk of particle contamination, lowering overall manufacturing costs, and improving the yield and reliability of the semiconductor manufacturing process.

[0032] The explanation will be given with reference to Figure 2. Figure 2 shows a flowchart of the method for forming the electrostatic chuck surface structure 10. The manufacturing method of the electrostatic chuck surface structure 10 in this embodiment will be described in detail below.

[0033] First, please refer to step S1. The first protective coating layer 13 is deposited on the substrate 12 under specific conditions using thermal spraying technology. Examples include atmospheric plasma spraying (APS), suspension plasma spraying (SPS), and vacuum plasma spraying (VPS). Details of these three thermal spraying technologies are as follows.

[0034] 1. Atmospheric Plasma Spraying (APS) Atmospheric plasma spraying (APS) is one of the most common techniques for depositing the first protective coating layer 13. In this method, the coating material is delivered to a high-temperature plasma jet, and the molten particles are ejected onto the substrate 12. APS is typically performed under atmospheric pressure and is suitable for a wide range of materials, including metal oxides, fluorides, and nitrides. By adjusting process parameters such as arc current (200A~600A), carrier gas flow rate (30L / min~200L / min), and turntable speed (5RPM~30RPM), the desired coating properties can be achieved.

[0035] 2. Suspension Plasma Spraying (SPS) Suspension plasma spraying (SPS) is a variation of conventional plasma spraying that 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. Process conditions are similar to APS, but additional control may be required to manage the suspension supply rate and plasma parameters.

[0036] 3. Vacuum Plasma Spraying (VPS) Vacuum plasma spraying is performed in a controlled vacuum environment, minimizing oxidation and contamination during the spraying process. This method is highly suitable for materials sensitive to atmospheric conditions. VPS allows for more precise control over 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 coating adhesion.

[0037] By applying the above-described thermal spraying technology, the first protective coating layer 13 can achieve the desired thickness, porosity, and hardness, thereby improving the wear resistance and corrosion resistance of the substrate 12.

[0038] Furthermore, the plasma spray deposition process is controlled by several parameters to achieve the desired coating properties. These include arc currents ranging from 200A to 600A, substrate rotation speeds from 5RPM to 30RPM, and the type of carrier gas, such as argon, nitrogen, or helium. The gas flow rate is also adjusted between 30L / min and 200L / min, and the process pressure can vary from 1 atmosphere to 1.0E-2 Torr. These ion spraying techniques are well-suited for depositing thick coatings ranging from 100μm to 250μm, providing robust protection for the metal components of electrostatic chucks.

[0039] Furthermore, a generally beneficial, though optional, step during the process is preheating the substrate 12. The preheating temperature of the substrate 12 is in the range of 100°C to 300°C, which helps to improve the adhesion and density of the deposited layer. Also, if the thermal properties of the substrate 12 material and the coating material are different, the preheating step of the substrate 12 significantly improves the adhesion between the substrate 12 and the first protective coating layer 13.

[0040] Next, refer to step S2 in Figure 2. A second protective coating layer 14 is deposited on the first protective coating layer 13 under optimized conditions using physical vapor deposition (PVD) technology. Physical vapor deposition (PVD) technologies include, for example, electron beam PVD (E-Gun PVD) and ion-assisted electron beam PVD, and the details of these two PVD technologies are as follows.

[0041] 1. Electron beam physical deposition (E-Gun PVD) Electron beam physical deposition (TEMD) is a highly specialized thin-film deposition method. In this technique, an electron beam is used to evaporate a source material, which is then condensed onto a substrate 12 to form a coating. This process is carried out in a high-vacuum chamber, allowing for precise control of the film's microstructure and properties. Deposition conditions, such as 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), can be finely adjusted. This method is particularly suitable for depositing coatings with high hardness (1000-1500 HV) and low porosity (<1%).

[0042] 2. Ion-assisted electron beam physical deposition This is an advanced variation of E-Gun PVD, which uses an ion source to assist the deposition process. Ion assistance helps improve the film density, adhesion, and other mechanical properties. Desired coating characteristics can be achieved by adjusting the parameters of the ion source, such as plasma power, electron beam current (0-1500 mA), and voltage (100V-1500V). The gas flow rates of argon and oxygen are adjustable in the ranges of 5 sccm to 50 sccm and 10 sccm to 200 sccm, respectively.

[0043] Both electron beam physical deposition (E-Gun PVD) and ion-assisted electron beam physical deposition are highly suitable for depositing a second protective coating layer 14 consisting of metal oxides, fluorides, and nitrides, with a thickness ranging from 0.5 μm to 20 μm.

[0044] Furthermore, the optimization conditions mentioned above include chamber temperature, deposition rate, and process pressure. Examples include chamber temperature (25°C to 200°C), deposition rate (0.1 nm / s to 1.5 nm / s), and plasma power of the ion source. The electron beam current can be adjusted from 0 to 1500 mA, and the voltage from 100V to 1500V.

[0045] Furthermore, argon and oxygen are used as carrier gases in physical vapor deposition (PVD) technology, with flow rates ranging from 5 sccm to 50 sccm and 10 sccm to 200 sccm, respectively. The process pressure is 1.0 × 10⁻⁶. -2 The above 1.0 × 10 -6 The Torr level is maintained below this level. These optimized deposition methods, materials, and process parameters result in the formation of a second protective coating layer 14 with superior properties that exceed the stringent requirements of semiconductor manufacturing, thereby significantly improving performance and extending the lifespan of the electrostatic chuck.

[0046] Therefore, compared to conventional methods of forming the surface structure of an electrostatic chuck using sintering, this method uses thermal spraying technology and physical vapor deposition technology to produce the first protective coating layer 13 and the second protective coating layer 14, thereby more effectively reducing the manufacturing cost of the electrostatic chuck surface structure 10.

[0047] Based on the above, the present invention provides a surface structure for electrostatic chucks and a method for forming the same, which not only meets but also exceeds the performance and durability requirements of modern semiconductor manufacturing processes. Therefore, the present invention represents a significant advance in this field, providing a combination of high hardness, low porosity, and excellent wear resistance in a cost-effective manner.

Claims

1. Substrate and A first protective coating layer provided on one surface of the substrate, The first protective coating layer includes a second protective coating layer provided on the first protective coating layer, The first protective coating layer is selected from the group consisting of metal oxides, fluorides, and nitrides, and has a thickness of 100 μm or more and 250 μm or less. The second protective coating layer is selected from the group consisting of metal oxides, fluorides, and nitrides, and has a thickness of 0.5 μm or more and 20 μm or less. The hardness of the first protective coating layer is 400 HV or more and 700 HV or less. The hardness of the second protective coating layer is 1000 HV or more and 1500 HV or less. The porosity of the first protective coating layer is 1% or more and 5% or less. The surface structure of the electrostatic chuck, wherein the porosity of the second protective coating layer is less than 1%.

2. The surface structure of the electrostatic chuck according to claim 1, wherein the second protective coating layer is formed by physical vapor deposition (PVD).

3. The surface structure of the electrostatic chuck according to claim 2, wherein the physical vapor deposition (PVD) is electron beam physical vapor deposition (E-Gun PVD) or ion-assisted electron beam physical vapor deposition.

4. The surface structure of the electrostatic chuck according to claim 1, wherein the first protective coating layer is a layer deposited by atmospheric plasma spraying (APS), suspension plasma spraying (SPS), or vacuum plasma spraying (VPS).

5. The electrostatic chuck surface structure according to claim 1, wherein the material of the first protective coating layer is selected from the group consisting of TiO2, Al2O3, YF3, Er2O3, Gd2O3, and Y2O3.

6. A step of forming a first protective coating layer on one surface of the substrate, The step includes forming a second protective coating layer on the first protective coating layer, The first protective coating layer is made of a material selected from the group consisting of metal oxides, fluorides, and nitrides, has a thickness of 100 μm to 250 μm, a Vickers hardness of 400 HV to 700 HV, and a porosity of 1% to 5%. A method for producing a surface structure for an electrostatic chuck, wherein the second protective coating layer is made of a material selected from the group consisting of metal oxides, fluorides, and nitrides, has a thickness of 0.5 μm or more and 20 μm or less, has a Vickers hardness of 1000 HV or more and 1500 HV or less, and has a porosity of less than 1%.

7. A method for producing a surface structure of an electrostatic chuck according to claim 6, further comprising the step of preheating the substrate to a temperature of 100°C to 300°C before forming the first protective coating layer.

8. The method for producing the surface structure of an electrostatic chuck according to claim 6, wherein the first protective coating layer is deposited by atmospheric plasma spraying, suspension plasma spraying, or vacuum plasma spraying.

9. The deposition conditions for the first protective coating layer are: The arc current is between 200A and 600A. The turntable's rotation speed is between 5 RPM and 30 RPM. The method for producing a surface structure of an electrostatic chuck according to claim 8, characterized in that the carrier gas is selected from the group consisting of argon, nitrogen, and helium, and the gas flow rate is 30 L / min or more and 200 L / min or less.

10. The method for producing the surface structure of an electrostatic chuck according to claim 6, characterized in that the second protective coating layer is deposited by electron beam physical deposition or ion-assisted electron beam physical deposition.

11. The deposition conditions for the second protective coating layer are: The chamber temperature is between 25°C and 200°C. The deposition rate is between 0.1 nm / s and 1.5 nm / s. The ion source plasma power-assisted electron beam current is 0 mA or more and 1500 mA or less. The voltage is between 100V and 1500V. The flow rate of argon gas is between 5 sccm and 50 sccm. The oxygen gas flow rate is between 10 sccm and 200 sccm. Process pressure is 1.0 × 10 -2 Torr or higher 1.0 × 10 -6 A method for producing a surface structure of an electrostatic chuck according to claim 10, wherein Torr is less than or equal to Torr.

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