Plasma-resistant coating film and method for preparing the same

Abstract

According to the present invention, the method for preparing a plasma-resistant coating film includes: step a, coating the powder of a first rare earth metal compound on a coating object by a physical vapor deposition process to form a lower coating; step b, transferring the powder of a second rare earth metal compound; and step c, spraying the transferred powder of the second rare earth metal compound onto the lower coating formed in step a to form an upper coating, thereby obtaining a plasma-resistant coating film with fewer structural defects and enhanced physical properties.

Description

Technical Field

[0001] The present invention relates to a method for preparing a plasma-resistant coating film, and more particularly, to a method for preparing a plasma-resistant coating film used in a semiconductor manufacturing process including a semiconductor etching device and the plasma-resistant coating film. Background Art

[0002] The next generation of semiconductors is developing in the direction of being lighter, thinner, shorter and smaller. As we enter the mobile era, semiconductor ultra-fine processes are absolutely necessary in order to be used in smaller and more complex electronic devices.

[0003] In particular, the difficulty of the etching process required for preparing semiconductor devices below 10nm, 3D NAND flash memory, FinField-Effect Transistor (FinFET), Magnetic Random Access Memory (MRAM), etc. is gradually increasing, so the development of technologies such as fine pattern etching for them is being actively carried out.

[0004] Therefore, the importance of etching technology development for new materials and etching technology for selectively etching only desired substances is expected to increase, and for this purpose, semiconductor components with durability that enable etching equipment to withstand extreme environments are absolutely required.

[0005] That is, in order to cope with ultra-fine line width processes, semiconductor components need to be coated at a high density in order to suppress the occurrence of contamination in high-power plasma (>10Kw) processes.

[0006] Generally speaking, a chamber of an equipment used in a semiconductor manufacturing process is made of a ceramic bulk such as aluminum alloy or alumina that has been anodized for insulation.

[0007] Recently, as the need for corrosion resistance to highly corrosive gases or plasmas has increased, in order to have such high corrosion resistance, a ceramic coating such as aluminum oxide is prepared on the aluminum alloy by methods such as plasma spraying or thermal spraying in a chamber used in a semiconductor manufacturing process using an evaporation equipment such as chemical vapor deposition (CVD) or an etching equipment such as plasma etching.

[0008] In addition, in the semiconductor manufacturing process carried out in the chamber, high-temperature processes such as heat treatment process, chemical vapor deposition, etc. account for the majority, so the chamber also needs to have heat resistance. In addition, the components of the semiconductor manufacturing equipment such as the chamber need to have insulation, heat resistance, corrosion resistance, plasma resistance, and the coating needs to maintain a strong bond with the substrate to prevent the coating from peeling off, thereby minimizing the occurrence of particles and the wafer contamination caused by them in the manufacturing process.

[0009] To this end, the conventional technology has applied the commonly used chemical vapor deposition method or physical vapor deposition (PVD) method or sputtering, but in this case, since it is a thin film preparation process, there are problems such as a long process time for forming a thick film that can meet the above-mentioned corrosion resistance and other conditions, which reduces the economic efficiency, and there is also a problem that it is difficult to obtain a strong bonding force between the substrate and the coating.

[0010] On the other hand, aerosol deposition is a method of spraying an aerosol containing ceramic particles from a nozzle toward a base material so that the particles collide with the base material and use the impact force to form a ceramic coating film on the base material. Since the powder to be coated is directly sprayed, high-speed coating can be performed, and high-speed coating of about 30 μm per minute can be achieved. Moreover, since the thickness is proportional to the number of times, the thickness can be controlled.

[0011] However, the aerosol deposition method has low adhesion due to the simple mechanical engagement between the coating film and the surface of the base material, which may cause problems such as peeling when used for a long time. In addition, the coating film is etched by CF4 plasma ions and free radicals used in the dry etching process, generating particles that may contaminate the wafer.

[0012] Next, the prior art existing in the technical field to which the present invention belongs is briefly described, and then the technical matters to be realized by the present invention are described.

[0013] Korean Patent Publication No. 10-2013-0123821 (publication date: November 13, 2013) relates to a plasma-resistant coating film, and describes a plasma-resistant coating film preparation technology, which forms an amorphous first coating film by applying a thermal spraying powder mixed with 30 wt% to 50 wt% of aluminum oxide and 50 wt% to 70 wt% of yttrium oxide on a coating object that needs to have plasma resistance by plasma thermal spraying, and forms a second coating film with higher density and plasma resistance on the first coating film by an aerosol deposition method to impart plasma resistance, high withstand voltage characteristics and high electrical resistance.

[0014] In addition, Korean Patent Publication No. 10-2017-0080123 (publication date: July 10, 2017) relates to a plasma-resistant coating film. Specifically, it describes a preparation technology of a plasma-resistant coating film, wherein after thermal spraying of a first rare earth metal compound, the plasma-resistant coating film is double-sealed by aerosol deposition and hydration treatment to minimize the open channels and open pores of the coating, thereby ensuring both chemical resistance and plasma corrosion resistance based on a dense rare earth metal compound coating film.

[0015] However, in the plasma-resistant coating film containing the multilayer coating prepared based on the above-mentioned existing documents, there are still problems such as peeling and generation of particles due to reduced bonding strength between the coating layers, and a preparation technology for a plasma-resistant coating film with durability and long life characteristics is needed.

[0016] Therefore, the present inventors realized that there are limitations in the method for preparing such a plasma-resistant coating film, optimized the bonding strength between the coating layers, and repeatedly studied a method for preparing a thin film having excellent plasma resistance, ultimately achieving the present invention.

[0017] Prior art literature

[0018] Patent Literature

[0019] Patent Document 1: Korean Patent Publication No. 10-2013-0123821

[0020] Patent Document 2: Korean Patent Publication No. 10-2017-0080123 Summary of the invention

[0021] Problem that the invention aims to solve

[0022] The main object of the present invention is to provide a method for preparing a plasma-resistant coating film, which has excellent bonding strength and suppresses the formation of structural defects in the coating film, thereby minimizing the peeling of the coating film or the generation of particles occurring in the semiconductor manufacturing process.

[0023] Another object of the present invention is to provide a plasma-resistant component having a plasma-resistant coating film formed thereon using the method for producing the plasma-resistant coating film.

[0024] Means used to solve problems

[0025] In order to achieve the above-mentioned purpose, one embodiment of the present invention provides a method for preparing a plasma-resistant coating film, which is characterized in that it includes: step a, applying the powder of a first rare earth metal compound on a coating object through a physical vapor deposition process to form a lower coating; step b, transferring the powder of a second rare earth metal compound; and step c, spraying the transferred powder of the second rare earth metal compound onto the lower coating formed in step a to form an upper coating.

[0026] In a preferred embodiment of the present invention, the first rare earth metal compound and the second rare earth metal compound may have the same composition.

[0027] In a preferred embodiment of the present invention, the rare earth metal compound can be selected from the group consisting of yttrium oxide (Y2O3), yttrium fluoride (YF), yttrium oxyfluoride (YOF), and yttrium aluminum garnet (YAG).

[0028] In a preferred embodiment of the present invention, the physical vapor deposition can be any one selected from thermal deposition, electron beam evaporation and sputtering.

[0029] In a preferred embodiment of the present invention, the thickness of the lower coating layer may be 0.1 μm to 10 μm.

[0030] In a preferred embodiment of the present invention, the average diameter (D50) of the powder of the second rare earth metal compound may be 0.1 μm to 10 μm.

[0031] In a preferred embodiment of the present invention, the thickness of the upper coating layer may be 1 μm to 30 μm.

[0032] According to another preferred embodiment of the present invention, the present invention provides a plasma-resistant coating film prepared by the method for preparing a plasma-resistant coating film.

[0033] Effects of the Invention

[0034] According to the method for preparing a plasma-resistant coating film of the present invention, a lower coating layer formed by spraying a first rare earth metal compound by physical vapor deposition is applied, and in the step of preparing an upper coating layer by spraying a powder of a second rare earth metal compound, the lower coating layer receives the impact force applied to the coating object by the powder of the second rare earth metal compound, so as to minimize the occurrence of structural defects that may occur in the upper coating layer containing the second rare earth metal compound.

[0035] The plasma-resistant coating film prepared according to the present invention reduces porosity that may be generated in structural defects by minimizing structural defects within the coating film, and exhibits a characteristic of improving the physical strength of the coating film. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a schematic diagram showing energy conversion that occurs when rare earth compound powder is sprayed onto a coating object to form a rare earth metal compound coating.

[0037] Figure 2 This is a scanning electron microscope (SEM) image of the side surface of the coating film prepared according to Comparative Example 1.

[0038] Figure 3 is a SEM picture of the side of the coating film prepared according to Example 1. DETAILED DESCRIPTION

[0039] Unless otherwise defined, all technical terms and scientific terms used in this specification have the same meanings as those commonly understood by those skilled in the art to which the invention belongs. The nomenclature generally used in this specification is a method widely known and commonly used in the art.

[0040] Throughout the specification of the present application, when it is mentioned that a certain part “includes” a certain constituent element, unless there is any special description to the contrary, it means that other constituent elements may also be included, rather than excluding other constituent elements.

[0041] The following Figure 1 This is a schematic diagram showing energy conversion that occurs when rare earth compound powder is sprayed onto a coating object to form a rare earth metal compound coating.

[0042] like Figure 1 As shown, when rare earth compound powder is sprayed onto a coating object to form a rare earth metal compound coating, the kinetic energy of the rare earth compound powder is converted into thermal energy and fracture energy, thereby generating structural defects such as cracks in the coating object and the coating.

[0043] To overcome such problems, the present invention provides a method for preparing a plasma-resistant coating film, which reduces the porosity of the coating film by minimizing structural defects generated in a rare earth metal compound coating layer and can exhibit the property of improving the physical strength of the coating film.

[0044] According to one aspect of the present invention, a method for preparing a plasma-resistant coating film is characterized in that it includes: step a, applying a powder of a first rare earth metal compound to a coating object through a physical vapor deposition process to form a lower coating; step b, transferring a powder of the second rare earth metal compound; and step c, spraying the transferred powder of the second rare earth metal compound onto the lower coating formed in step a to form an upper coating, wherein the first rare earth metal compound and the second rare earth metal compound have the same composition.

[0045] First, in the method for forming a plasma-resistant coating film according to the present invention, a powder of a first rare earth metal compound is applied to a coating object by a physical vapor deposition process to form a lower coating layer (step a).

[0046] The coating object formed with the lower coating layer containing the first rare earth metal compound can be a plasma device component such as an electrostatic chuck, a heater, a chamber liner, a shower head, a CVD boat, a focus ring, a wall liner, etc. used in the interior of a plasma device. The material of the coating object can be metals such as iron, magnesium, aluminum and their alloys; ceramics such as SiO2, MgO, CaCO3, alumina, etc.; polymers such as polyethylene terephthalate, polyethylene naphthalate, polypropylene adipate, polyisocyanate, etc., but is not limited to these.

[0047] The first rare earth metal compound may include yttrium oxide (Y2O3), yttrium fluoride (YF), yttrium oxyfluoride (YOF), yttrium aluminum garnet (YAG) or a mixture thereof, and specifically, yttrium oxide (Y2O3) is preferred.

[0048] The first rare earth metal compound forming the upper coating has strong resistance to plasma exposure in semiconductor processes. Therefore, when applied to semiconductor equipment parts requiring corrosion resistance such as semiconductor etching equipment, it can ensure corrosion resistance and voltage resistance characteristics to plasma in semiconductor processes.

[0049] When forming an upper coating on the coating object, any physical vapor deposition method can be used without restriction as long as it is used to form a coating that can meet the conditions such as strong bonding force and corrosion resistance between the coating object and the coating. Specifically, the physical vapor deposition can be any one selected from thermal deposition, electron beam evaporation and sputtering. Preferably, it can be electron beam evaporation.

[0050] In step a, the lower coating layer containing the first rare earth metal compound is formed by coating the first rare earth metal compound on the coating object by physical vapor deposition. The lower coating layer is etched during the preparation process of the upper coating layer. Therefore, when the hardness of the powder of the rare earth metal compound forming the upper coating layer is high or the heat treatment temperature of the powder of the rare earth metal compound is higher, it is preferred to increase the thickness of the lower coating layer. Alternatively, in the process of forming the upper coating layer, the smaller the nozzle angle, the greater the etching amount of the lower coating layer. Therefore, it is preferred to increase the thickness of the lower coating layer.

[0051] In one embodiment, preferably, the thickness of the lower coating is 0.1 μm to 10 μm. If the thickness of the lower coating is less than 0.1 μm, a portion of the lower coating may not be formed. If the thickness exceeds 10 μm, the process cost is increased, thereby reducing the economic efficiency.

[0052] Thereafter, a transfer gas is supplied to transfer the powder of the second rare earth metal compound, thereby transferring the powder of the second rare earth metal compound (step b).

[0053] At this time, the transfer gas may be provided at a flow rate of 15 slm to 200 slm (standard liter per minute). The transfer gas may include, for example, an inert gas (such as argon).

[0054] Subsequently, the second rare earth metal compound powder is sprayed onto the lower coating layer formed on the coating object to form an upper coating layer including the second rare earth metal compound, thereby forming a plasma-resistant component including the coating object and the rare earth metal compound coating film (step c).

[0055] The second rare earth metal compound may include yttrium oxide (Y2O3), yttrium fluoride (YF), yttrium oxyfluoride (YOF), yttrium aluminum garnet (YAG) or a mixture thereof, and specifically, yttrium oxide (Y2O3) is preferred.

[0056] At this time, preferably, the first rare earth metal compound as a constituent component of the lower coating and the second rare earth metal compound as a constituent component of the upper coating are the same composition, and the internal stress of the coating film can be minimized by setting the lower coating and the upper coating to the same composition, thereby forming a stable coating film.

[0057] Through the heat treatment process according to the present invention, the powder of the second rare earth metal compound has an average diameter (D50) of 0.1 μm to 10 μm, thereby improving the density, strength and adhesion of the coating film when the upper coating layer is prepared from the powder of the second rare earth metal compound.

[0058] The upper coating layer including the second rare earth metal compound has a thickness of 1.0 μm to 30 μm, and is preferably a high-density rare earth metal compound having a porosity of less than 1.0 vol%.

[0059] As the porosity of the upper coating increases, the mechanical strength of the plasma-resistant coating film finally formed decreases. Therefore, preferably, the upper coating including the second rare earth metal compound is low in porosity and dense to ensure the mechanical strength of the plasma-resistant coating film.

[0060] However, in general, when the powder of a rare earth metal compound is transferred using a transfer gas and then formed into a coating film using a deposition method in which deposition is performed through a nozzle in a vacuum chamber, the coating film has a nanoscale crystalline structure including many grain boundaries inside, and structural defects such as cracks are generated due to the fracture energy generated during deposition, and therefore generally have lower mechanical properties.

[0061] Therefore, the present invention applies a first rare earth metal compound to a lower coating by physical vapor deposition, so that in the step of preparing an upper coating, the lower coating receives the thermal energy and fracture energy applied to the coating object by the powder of the second rare earth metal compound, thereby minimizing the occurrence of structural defects in the coating film.

[0062] In addition, when the thickness of the upper coating is less than 1 μm, it is too thin to ensure plasma resistance in a plasma environment, and when the thickness of the upper coating is greater than 30 μm, peeling of the upper coating may occur during processing, and economic losses may be caused due to excessive use of rare earth metal compounds.

[0063] As one embodiment, in the deposition process of forming the upper coating layer using a transfer gas of a second rare earth metal compound powder, the second rare earth metal compound powder is loaded into a vacuum chamber, and the coating object formed with the lower coating layer is placed in the deposition chamber. At this time, the second rare earth metal compound powder is supplied from the vacuum chamber and injected into the deposition chamber by the transfer gas, thereby being sprayed.

[0064] As the transfer gas, in addition to argon (Ar), compressed air, or inert gases such as hydrogen (H2), helium (He) or nitrogen (N2) can also be used. Due to the pressure difference between the supply device of the second rare earth metal compound powder and the deposition chamber, the second rare earth metal compound powder is sucked into the deposition chamber together with the transfer gas, and is sprayed at high speed through the nozzle to the coating object (parent material) formed with the lower coating.

[0065] Thus, the second rare earth metal compound is deposited by the spraying, thereby forming an upper coating layer including a high density of the second rare earth metal compound. The deposition area of ​​the second rare earth metal compound coating layer can be controlled to a desired size by moving the nozzle left and right, and its thickness is also determined by being proportional to the deposition time (i.e., the spraying time).

[0066] The upper coating layer may be formed by repeatedly stacking the powder of the second rare earth metal compound two or more times using the deposition method.

[0067] Furthermore, the present invention provides a plasma-resistant coating film produced by the method for producing a plasma-resistant coating film, and the plasma-resistant coating film has a low porosity and exhibits improved physical strength.

[0068] Hereinafter, the present invention will be described in more detail by way of examples. However, the following examples are merely examples of the present invention, and the present invention is not limited to the following examples.

[0069] Comparative Example 1

[0070] Deposition is performed in a vacuum chamber in a low vacuum state, and the highest vacuum degree that can be achieved is 10mTorr. The process vacuum degree formed when supplying transfer gas is 0.5Torr to 5Torr.

[0071] The yttrium oxide (Y2O3) powder is uniformly supplied in a prescribed amount by a supply device. The supplied yttrium oxide (Y2O3) powder is several μm to several tens of μm, and at this time, the powder supply amount is controlled at a level of 5g to 50g per minute.

[0072] The supplied powder is transferred along with the flow of the transfer gas and finally ejected through the nozzle in the chamber. The flow rate of the supplied transfer gas is 15SLM to 200SLM, and the type of gas is an inert gas such as argon (Ar), nitrogen (N2), helium (He), etc.

[0073] When the transfer gas is supplied, the transfer gas is sucked into the vacuum chamber due to the pressure difference generated between the powder supply device and the vacuum chamber. The flow of gas generated at this time causes the powder and the transfer gas to mix and transfer.

[0074] The transferred powder particles are further accelerated by the pressure difference and reach the speed of sound when ejected through the nozzle. The accelerated powder particles collide with the base material, and based on the collision energy generated at this time, a yttrium oxide coating film with a thickness of 10 μm is formed.

[0075] Embodiments 1 to 4

[0076] The coating material or process conditions of the AD coating may vary depending on the thickness of the PVD coating. If the thickness of the PVD coating is thin, a coating material or process condition with a low etching rate (Etching rate) is required. In the case of a material or process condition with a high etching rate (Etching rate), the PVD coating will be completely etched, so the thickness of the PVD coating needs to be increased. Therefore, according to the material and process conditions of the AD coating, the thickness of the PVD coating varies to 0.5μm, 1.0μm, 1.5μm, and 3.0μm, respectively.

[0077] An example of the lower layer applied by electron beam deposition among the physicochemical deposition methods is as follows.

[0078] First, the alumina matrix is ​​mirror-polished and then placed in a coating chamber together with yttrium oxide (Y2O3) as a raw material, thereby maintaining a high vacuum atmosphere. At this time, the chamber temperature is kept below 300°C.

[0079] When the chamber reaches a high vacuum, an electron beam is irradiated to yttrium oxide (Y2O3) to melt the yttrium oxide and deposit it on the base material. At this time, ion assist is applied to improve the physical properties of the coating.

[0080] The coating was performed by adjusting the coating time so that the final coating thickness would be 0.5 μm, 1.0 μm, 1.5 μm, or 3.0 μm.

[0081] On the PVD coatings of various thicknesses prepared as above, AD coatings were deposited in the same manner as in the comparative example.

[0082] Table 1

[0083] PVD coating thickness (μm) Hardness(Hv) Porosity (%) Are there cracks in the coating? Comparative Example 1 - 10.271 1.12 ○ Example 1 0.5 10.621 0.21 × Example 2 1.0 10.412 0.24 × Example 3 1.5 10.324 0.23 × Example 4 3.0 10.512 0.22 ×

[0084] As shown in Table 1 above, the plasma-resistant coating films (Examples 1 to 4) according to the present invention have reduced porosity of the AD coating that can be generated in structural defects, compared with the coating film not including the PVD lower coating film (Comparative Example 1), and exhibit the characteristic of improving the physical strength of the coating film.

[0085] Above, specific parts of the present invention are described in detail. It should be clear that for those skilled in the art, these specific descriptions are only preferred embodiments, and the protection scope of the present invention is not limited thereto. Therefore, the essential scope of the present invention will be defined by the attached claims and their equivalents.

Claims

1. A method for preparing a plasma-resistant coating film, characterized in that: The method for preparing the plasma-resistant coating film comprises: Step a, coating a first rare earth metal compound powder on a coating object by a physical vapor deposition process to form a lower coating layer with a thickness of 0.1 μm to 10 μm; Step b, transferring a powder of a second rare earth metal compound; and Step c, spraying the transferred second rare earth metal compound powder onto the lower coating layer formed in step a to form an upper coating layer, The first rare earth metal compound and the second rare earth metal compound are selected from the group consisting of yttrium oxide (Y2O3), yttrium oxyfluoride (YOF), and yttrium aluminum garnet, The first rare earth metal compound and the second rare earth metal compound have the same composition.

2. The method for preparing a plasma-resistant coating film according to claim 1, characterized in that: The physical vapor deposition process is selected from any one of thermal deposition, electron beam evaporation and sputtering.

3. The method for preparing a plasma-resistant coating film according to claim 1, characterized in that: The average diameter D50 of the second rare earth metal compound powder is 0.1 μm to 10 μm.

4. The method for preparing a plasma-resistant coating film according to claim 1, wherein: The upper coating layer has a thickness of 1 μm to 30 μm.

5. A plasma-resistant coating film, characterized in that: The plasma-resistant coating film is produced by the method for producing a plasma-resistant coating film according to any one of claims 1 to 4.

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