Surface structure of 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 have been surface-treated 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 wafer loading and unloading may cause wear on the protruding parts of the chuck, and this wear may conversely cause particulate matter to adhere to the back 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 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] The present invention solves the limitations and problems of the electrostatic chucks (ESCs) used in conventional 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 functions as a robust base, protects the underlying substrate, and improves 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 is thinner with a thickness ranging from 0.5 μm to 20 μm. Despite being thin, this layer provides an ultra-high hardness in the range of 1000 HV to 1500 HV, and the porosity is less than 1%. These properties are very effective in reducing particle contamination from the chuck to the wafer, resulting in an improvement in the yield of subsequent semiconductor processes. In addition to the structural properties, another object of the present invention is to provide a method for forming the surface structure of the electrostatic chuck.

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

[0010] By providing a combination of high hardness, low porosity, and wear resistance in a cost-effective manner, the present invention has significantly advanced the state of the art in electrostatic chuck technology for semiconductor manufacturing. That is, the present invention has the following advantages: it has high hardness, high density, wear resistance, and can reduce the manufacturing cost of the surface structure of the electrostatic chuck.

[0011] To more clearly understand the above features and advantages of the present invention, the following preferred embodiments will be given and described in detail with reference to the accompanying drawings.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0013] This will be described with reference to FIG. 1. FIG. 1 shows a schematic diagram of the surface structure 10 of the electrostatic chuck of the present embodiment. The present invention provides a surface structure of an advanced electrostatic chuck (ESC) having a unique surface structure designed to meet the stringent requirements of modern semiconductor manufacturing processes. The surface structure 10 of the electrostatic chuck of the present 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 usually manufactured from a conductive or semiconductor material and can generate an electrostatic field. This electrostatic field serves to fix the semiconductor wafer in various manufacturing processes. In the present embodiment, the substrate 12 can be manufactured from aluminum, silicon, or other metals and ceramic materials commonly used in the industry.

[0015] The substrate 12 is a base element of the electrostatic chuck and plays an important role in the performance and function of the entire electrostatic chuck. Usually, a protective layer is deposited on the substrate 12, and the substrate 12 is responsible for generating an electrostatic field that fixes the semiconductor wafer during the manufacturing process.

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

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

[0018] In addition, before depositing the protective layer, the substrate 12 generally undergoes a series of surface preparation processes. This may include cleaning, etching, and priming to remove surface contaminants and promote the 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 permittivity, are also adjusted to optimize the electrostatic holding force. These properties are particularly important when handling extremely thin or irregularly shaped wafers, ensuring that the wafer is securely fixed throughout the manufacturing process.

[0020] Referring back to FIG. 1 for explanation. The first protective coating layer 13 is provided directly on the surface of the substrate 12 and serves to extend 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 of 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 adopting physical vapor deposition in vacuum, a protective coating with higher hardness and lower porosity can be generated. 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, is ideal for long-term contact with the semiconductor wafer, and is very effective in reducing particle contamination from the chuck to the wafer.

[0031] As described above, the second protective coating layer 14 directly contacts the semiconductor wafer as the outermost layer, provides ultra-high hardness, low porosity, and excellent wear resistance, and improves 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 drawbacks of conventional electrostatic chucks, not only strengthens the wear resistance, but also significantly reduces the risk of particle contamination, reduces the overall manufacturing cost, and improves the yield and reliability of the semiconductor manufacturing process.

[0032] This will be described with reference to FIG. 2. FIG. 2 shows a flowchart of a method for forming the electrostatic chuck surface structure 10. Hereinafter, the manufacturing method of the electrostatic chuck surface structure 10 of this embodiment will be described in detail.

[0033] First, refer to step S1. The first protective coating layer 13 is deposited on the substrate 12 under specific conditions using a thermal spraying technique. For example, atmospheric plasma spraying (APS), suspension plasma spraying (SPS), vacuum plasma spraying (VPS), etc. The details of these three thermal spraying techniques are as follows.

[0034] 1. Atmospheric plasma spraying (APS) Atmospheric plasma spraying is one of the most common techniques for depositing the first protective coating layer 13. In this method, the coating material is sent into a high-temperature plasma jet, and the molten particles are sprayed towards the substrate 12. APS is usually carried out under atmospheric pressure and is suitable for a wide range of materials such as metal oxides, fluorides, nitrides, etc. 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.

[0035] 2. Suspension Plasma Spraying (SPS) Suspension plasma spraying is a variant of conventional plasma spraying that uses a suspension of fine powder particles in a liquid medium. This method enables the deposition of layers with unique microstructures and enhanced properties. SPS is particularly suitable for the deposition of 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.

[0036] 3. Vacuum Plasma Spraying (VPS) Vacuum plasma spraying is carried out in a controlled vacuum environment, minimizing oxidation and contamination during the spraying process. This method is very suitable for materials sensitive to atmospheric conditions. VPS enables more precise 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.

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

[0038] Also, the deposition process of plasma spraying is controlled by several parameters to achieve the desired coating properties. These include an arc current of 200A to 600A, a substrate rotation speed of 5RPM to 30RPM, and the type of carrier gas such as argon, nitrogen, helium, etc. Also, the gas flow rate is adjusted between 30L / min and 200L / min, and the process pressure can vary from 1 atmosphere to 1.0E-2 Torr. These ion spraying technologies are very suitable for depositing thick coatings in the range of 100μm to 250μm and provide strong protection for the metal parts of the electrostatic chuck.

[0039] Furthermore, as an optional but usually beneficial step during the process, there is preheating of the substrate 12. The preheating temperature of the substrate 12 is in the range of 100°C to 300°C and helps to improve the adhesion and density of the deposited layer. Also, when the thermal properties of the material of the substrate 12 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. On top of the first protective coating layer 13, a second protective coating layer 14 is deposited under optimized conditions using physical vapor deposition (PVD) technology. Physical vapor deposition (PVD) technologies include, for example, electron beam physical vapor deposition (E-Gun PVD) and ion-assisted electron beam physical vapor deposition, and the details of these two physical vapor deposition technologies are as follows.

[0041] 1. Electron beam physical vapor deposition (E-Gun PVD) Electron beam physical vapor deposition is a highly specialized thin film deposition method. In this technique, an electron beam is used to evaporate the source material, which then condenses onto the substrate 12 to form a coating. This process is carried out in a high vacuum chamber, and it is possible to precisely control the microstructure and properties of the film. The deposition conditions can be finely adjusted, such as the chamber temperature (from 25°C to 200°C), deposition rate (from 0.1 nm / s to 1.5 nm / s), process pressure (from 1.0E-2 to 1.0E-6 Torr), etc. 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 Vapor Deposition This is an advanced variation of E-Gun PVD that uses an ion source to assist in the deposition process. Ion assistance helps improve the density, adhesion, and other mechanical properties of the film. The parameters of the ion source, such as plasma power, electron beam current (0 - 1500 mA), voltage (100V - 1500V), can be adjusted to achieve the desired coating properties. The gas flow rates of argon and oxygen can be adjusted in the ranges of 5 sccm to 50 sccm and 10 sccm to 200 sccm, respectively.

[0043] Both of these 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 layer 14 composed of metal oxides, fluorides, and nitrides, and its thickness ranges from 0.5μm to 20μm.

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

[0045] Furthermore, as carrier gases used in physical vapor deposition (PVD) technology, there are argon and oxygen, and their flow rate ranges are from 5 sccm to 50 sccm and from 10 sccm to 200 sccm, respectively. The process pressure is maintained at 1.0×10 -2 or more and 1.0×10 -6 Torr or less. With these optimized deposition methods, materials, and process parameters, a second protective coating layer 14 with excellent properties exceeding the strict requirements of semiconductor manufacturing is formed. As a result, the performance is significantly improved and the life of the electrostatic chuck is extended.

[0046] Therefore, compared with the method of forming the surface structure of the electrostatic chuck using the conventional sintering method, in this method, the thermal spraying technology and the physical vapor deposition technology are selected to fabricate the first protective coating layer 13 and the second protective coating layer 14, so that the manufacturing cost of the electrostatic chuck surface structure 10 can be more effectively reduced.

[0047] From the above, the present invention provides a surface structure of an electrostatic chuck and a method for forming the same, which not only meet but also exceed the performance and durability requirements of modern semiconductor manufacturing processes. Therefore, the present invention represents an important advancement in this field and provides a combination of high hardness, low porosity, and excellent wear resistance in a cost-effective manner.

Claims

1. A substrate; a first protective coating layer disposed on one surface of the substrate; a second protective coating layer disposed on the first protective coating layer; The surface structure of an electrostatic chuck, 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%.

2. 2. The surface structure of an electrostatic chuck according to claim 1, wherein the porosity of the second protective coating layer is less than the porosity of the first protective coating layer.

3. 2. The surface structure of an electrostatic chuck according to claim 1, wherein the first protective coating layer is selected from the group consisting of metal oxides, fluorides and nitrides, and has a thickness of 100 μm to 250 μm.

4. 2. The surface structure of an electrostatic chuck according to claim 1, wherein the hardness of the first protective coating layer is 400 HV or more and 700 HV or less.

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

6. 2. The surface structure of an electrostatic chuck according to claim 1, wherein 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 to 20 μm.

7. 2. The surface structure of an electrostatic chuck according to claim 1, wherein the hardness of the second protective coating layer is 1000 HV or more and 1500 HV or less.

8. forming a first protective coating layer on one surface of a substrate; forming a second protective coating layer on the first protective coating layer; 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. 10. The method of claim 8, further comprising preheating the substrate to a temperature of 100° C. to 300° C. prior to forming the first protective coating layer.

10. 10. The method of claim 8, wherein the first protective coating layer is deposited by air plasma spraying, suspension plasma spraying, or vacuum plasma spraying.

11. The deposition conditions of the first protective coating layer are: The arc current is 200 A or more and 600 A or less, The rotation speed of the turntable is 5 RPM or more and 30 RPM or less, 11. The method for fabricating a surface structure of an electrostatic chuck according to claim 10, wherein 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.

12. 10. The method of claim 8, wherein the second protective coating layer is deposited by electron beam physical vapor deposition or ion-assisted electron beam physical vapor deposition.

13. The deposition conditions of the second protective coating layer are: The chamber temperature is 25° C. or higher and 200° C. or lower, The deposition rate is 0.1 nm / s or more and 1.5 nm / s or less, The ion source plasma power assist electron beam current is 0 mA or more and 1500 mA or less, The voltage is 100V or more and 1500V or less, The flow rate of the argon gas is 5 sccm or more and 50 sccm or less, The flow rate of the oxygen gas is 10 sccm or more and 200 sccm or less, The process pressure is 1.0×10 -2 Torr or higher 1.0 x 10 -6 13. The method for fabricating a surface structure for an electrostatic chuck according to claim 12, wherein the surface roughness is equal to or less than Torr.

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