Chemical vapor deposition apparatus for forming polyvinylidene fluoride and copolymer thereof

Abstract

An embodiment of the present invention relates to a chemical vapor deposition apparatus for forming a polyvinylidene fluoride and a copolymer thereof by using a chemical vapor deposition method. An embodiment of the present invention provides a chemical vapor deposition (CVD) apparatus for performing chemical vapor deposition to form a polyvinylidene fluoride and a copolymer thereof on a substrate, the chemical vapor deposition apparatus comprising: a chamber having a light-transmitting portion; a gas source supply unit for supplying the chamber with a vinylidene fluoride monomer gas and an initiator gas; a light source for supplying ultraviolet rays into the chamber through the light-transmitting portion; and a susceptor which is positioned within the chamber and has a refrigerant circulation unit formed therein, wherein the substrate is placed on the susceptor.

Description

Chemical vapor deposition apparatus for forming polyvinylidene fluoride and its copolymers

[0001] An embodiment of the present invention relates to a chemical vapor deposition apparatus for forming polyvinylidene fluoride and its copolymer using a chemical vapor deposition method.

[0002]

[0003] PVDF is a polymer material with strong CF bonds that exhibit chemical resistance, weather resistance, oxidation stability, heat resistance, low gas and liquid permeability, and low surface energy. Because PVDF has polymorphic characteristics, it can provide customized properties for various industries, making its application possibilities endless. PVDF undergoes crystal phase transitions to α, β, and γ through bonding methods such as TGTG and TTTT, and through mechanical deformation, high electric fields, high temperature and high pressure stretching, and heat treatment, and each crystal phase has its own unique properties. PVDF has relatively stable chemical resistance except for basic solutions, esters, and ketones, and is mechanically stronger than perfluoropolymers such as PTFE, and has high wear resistance, creep resistance under long-term stress, and fatigue resistance during repeated loading.

[0004]

[0005] A popular process for synthesizing PVDF involves dissolving the VDF monomer in a fluorinated solvent, such as hexafluoroisopropanol (HFIP), and spin-coating the solution onto the desired substrate. The temperature is then raised to 70°C, inducing a polymer synthesis reaction via free radicals within the solution, simultaneously forming a thin film and evaporating the solvent. Furthermore, the Langmuir-Blodgett (LB) method is a useful method for forming monolayer thin films. It utilizes surface tension to induce the desired substance onto the surface of a specific solution. The substrate is then exposed to the solution, similar to dip-coating, to form a monolayer thin film.

[0006]

[0007] However, when synthesizing PVDF films using a solution process, it is difficult to form films with thicknesses on the order of nanometers. Furthermore, post-processing is required to remove solvents from the process, and there are issues with residual solvents remaining in the synthesized PVDF.

[0008]

[0009] Furthermore, conventional solution processes use N-methylpyrrolidone (NMP) to dissolve significant amounts of PVDF at room temperature. However, NMP is highly toxic, causing central nervous system, liver, and kidney toxicity and carcinogenicity, and is also environmentally hazardous. Solvents such as N,N-dimethyl formamide (DMF) and N,N-dimethyl acetamide (DMAc) have been used as replacements, but they still pose toxicity and human health risks.

[0010]

[0011] CVD is a process that synthesizes thin films through chemical reactions involving the absorption of a vaporized source without solvent. By controlling the reaction environment, such as temperature, PVDF thin films ranging from a few nanometers to tens of micrometers thick can be formed using only a very small amount of source. This reduces the burden on workers performing the process from being exposed to hazardous environments and eliminates solvents altogether, thereby alleviating environmental pollution.

[0012] Therefore, attempts have been made to synthesize PVDF-based polymers using CVD. However, VDF monomers exhibit a significant electron cloud bias due to their inherent polarity, making it difficult to initiate polymerization via radicals. Furthermore, their small molecular weights result in vapor pressures exceeding atmospheric pressure at room temperature, making it difficult to adsorb VDF monomers onto substrates.

[0013]

[0014] Embodiments of the present invention provide a chemical vapor deposition apparatus for forming polyvinylidene fluoride and its copolymers, which can form a polyvinylidene fluoride thin film using a chemical vapor deposition method.

[0015] And, embodiments of the present invention are intended to provide a chemical vapor deposition apparatus for forming polyvinylidene fluoride and its copolymer, which is environmentally friendly and safe for the human body during the process of forming polyvinylidene fluoride.

[0016]

[0017] According to one embodiment of the present invention, a chemical vapor deposition (CVD) apparatus for performing chemical vapor deposition for forming polyvinylidene fluoride and a copolymer thereof on a substrate is provided, the apparatus comprising: a chamber in which a light source transmitting portion is formed; a gas source supply portion for supplying vinylidene fluoride monomer gas and an initiator gas to the chamber; a light source for supplying ultraviolet rays and ultraviolet light into the chamber through the light source transmitting portion; and a susceptor positioned within the chamber, the susceptor having the substrate mounted thereon and a coolant circulation portion formed therein.

[0018]

[0019] At least one flow controller for controlling the flow rate of each of the vinylidene fluoride monomer gas and the initiator gas may be arranged in the gas source supply unit.

[0020] The above initiator is CF m X n (X can be one of Cl, Br, or I).

[0021] To prevent corrosion by the above byproducts, the chamber and the outlet may be formed with an anti-corrosion coating.

[0022]

[0023] According to an embodiment of the present invention, CF is formed through photolysis m Xn A chemical vapor deposition device for forming polyvinylidene fluoride and its copolymers, which can form a polyvinylidene fluoride thin film by enabling polymerization of a polymer through chemical vapor deposition by decomposing an initiator into radicals, is provided.

[0024] And, according to an embodiment of the present invention, a chemical vapor deposition apparatus for forming polyvinylidene fluoride and its copolymer is provided, which is environmentally friendly and safe for the human body, since no toxic solvent is required for use in a solution process.

[0025]

[0026] Figure 1 is a schematic diagram of a chemical vapor deposition apparatus according to one embodiment of the present invention.

[0027] Figure 2 is a drawing showing a process in which an initiator according to one embodiment of the present invention is photodecomposed to form radicals.

[0028] Figure 3 is a drawing showing the water-repellent surface state on a substrate in various cases.

[0029] FIG. 4 is a graph showing the results of X-ray photoelectron spectroscopy (XPS) for polyvinylidene fluoride formed according to one embodiment of the present invention.

[0030]

[0031] Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. The following detailed description is provided to facilitate a comprehensive understanding of the methods, devices, and / or systems described herein. However, this is merely an example, and the disclosed embodiments are not limited thereto.

[0032] In describing the embodiments, if it is determined that a specific description of related known technology may unnecessarily obscure the gist of the disclosed embodiments, the detailed description will be omitted. In addition, the terms described below are terms defined in consideration of their functions in the disclosed embodiments, and this may vary depending on the intention or custom of the user or operator. Therefore, the definitions should be made based on the contents throughout this specification. The terminology used in the detailed description is only for the purpose of describing the embodiments and should not be limited in any way. Unless clearly used otherwise, the singular form includes the plural form. In this description, expressions such as "comprises" or "having" are intended to indicate certain features, numbers, steps, operations, elements, parts or combinations thereof, and should not be construed to exclude the presence or possibility of one or more other features, numbers, steps, operations, elements, parts or combinations thereof other than those described.

[0033]

[0034] FIG. 1 is a schematic diagram of a chemical vapor deposition apparatus (100) according to one embodiment of the present invention.

[0035]

[0036] Referring to FIG. 1, a chemical vapor deposition apparatus (100) for forming polyvinylidene fluoride (PVDF) and its copolymer according to an embodiment of the present invention may include a chamber (110), a light source (130) for supplying ultraviolet (UV) and infrared rays into the chamber (110), a gas source supply unit (171, 172) for supplying a gas for chemical vapor deposition, such as vinylidene fluoride monomer gas, into the chamber (110), and a susceptor (120) positioned within the chamber (110) on which a substrate (S) is mounted. Ultraviolet rays must be irradiated into the chamber (110), and for this purpose, a light source transmitting unit (115) may be formed in the chamber (110).

[0037]

[0038] A gas source supply unit can supply vinylidene fluoride (VDF) monomer gas (171) and an initiator gas (172) to the chamber (110), and optionally, can supply an additional monomer gas that forms a copolymer with vinylidene fluoride. The additional monomer gas can include a monomer gas selected from trifluoroethylene (TrFE), chlorotrifluoroethylene (CTFE), hexafluoropropylene (HFP), and the like. The additional monomer gas can be polymerized with the vinylidene fluoride monomer gas (171) through chemical vapor deposition to form a copolymer on the substrate (S).

[0039] In addition, a flow controller (174) may be arranged in the gas source supply unit to control the flow rate of each of the vinylidene fluoride monomer gas (171), the initiator gas (172), and the additional monomer gas. The flow controller (174) may be formed on each gas supply path to control the flow rate of each gas and may be arranged according to the number of gas supply paths. Since the vinylidene fluoride monomer gas (171) and the initiator gas (172) supplied from the gas source supply unit have very small molecular weights, they are supplied in the form of gas, and the flow controller (174) is necessary to accurately control the amount of gas injected.

[0040]

[0041] Here, the initiator gas (172) is CF m X n (X can be one of Cl, Br, I). In the case of vinylidene fluoride monomer, since the vapor pressure is low, it is difficult to decompose the initiator into radicals through heat because the substrate (S) must be kept at an extremely low temperature in order to be adsorbed on the substrate (S). Therefore, CF as an initiator m X n (X is one of Cl, Br, and I) and a method of forming radicals through photodecomposition by irradiating the initiator with ultraviolet rays can be used.

[0042]

[0043] The gas supplied from the gas source supply unit flows into the chamber (110) through the inlet (175) and can be chemically vapor deposited on the substrate (S) on the susceptor (120) to form polyvinylidene fluoride (PVDF). As described above, the temperature at which radicals formed by the vinylidene fluoride monomer and the initiator on the substrate (S) are adsorbed is an ultra-low temperature environment of around 150 K. In order to implement such an ultra-low temperature environment, the susceptor (120) must be maintained at an ultra-low temperature, and for this purpose, a coolant circulation unit (160) is formed in the susceptor (120) to lower the temperature of the susceptor (120) through the coolant. LN2, L-He, etc. can be used as the coolant.

[0044] An extremely low temperature environment must be maintained at least around the susceptor (120) of the chamber (110), and in such an environment, moisture, oxygen, and other substances may be permanently adsorbed on the chamber (110). To prevent this, the chamber (110) may be placed inside a glove box (not shown) and the inside of the glove box may be filled with a gas atmosphere (e.g., argon (Ar) atmosphere) having a freezing point lower than that of nitrogen molecules.

[0045]

[0046] In order to convert the initiator gas (172) into radicals within the chamber (110), ultraviolet rays irradiated from a light source (130) located outside the chamber (110) can reach the chamber (110). For this purpose, a light source transmitting portion (115) may be formed in the chamber (110). The light source transmitting portion (115) may be formed of high-purity quartz, and the light source (130) may be positioned at the upper side of the chamber (110) and the light source transmitting portion (115) may be formed at the upper part of the chamber (110). In addition, an analysis device (not shown) may be placed outside the chamber (110) to analyze polyvinylidene fluoride formed on a substrate (S) through chemical vapor deposition in real time. The analysis device may use FTIR (Fourier Transform Infrared) / Raman spectroscopy. To utilize the analysis device, a light source transmitting portion (115) may be used in the chamber (110), or a separate window (not shown) may be installed. Furthermore, the light source (130) may irradiate not only ultraviolet rays but also infrared rays to induce a polymer chain reaction (propagation) by an initiator converted into radicals. Accordingly, the light source (130) may irradiate ultraviolet rays and infrared rays.

[0047]

[0048] The halogen element that will be generated as a byproduct after chemical vapor deposition can be discharged to the outside through a pump (P) connected to an exhaust port (180) formed in the chamber (110). In addition, an internal corrosion coating can be applied to the chamber (110) to prevent the halogen element, which is a byproduct, from causing corrosion within the chamber (110).

[0049]

[0050] FIG. 2 is a drawing showing a process in which an initiator according to one embodiment of the present invention is photodecomposed to form radicals.

[0051]

[0052] Referring to Figure 2, CF using ultraviolet raysm X n (X is one of Cl, Br, and I) can form radicals from the initiator. Vinylidene fluoride (VDF) has a very large bias in its electron cloud due to the polarity of the molecule itself. To overcome this bias in its electron cloud, CF m X n The initiator of the structure can be used. CF m X n When the initiator is photolyzed, it can be decomposed into CF2 radicals and halogen element X radicals. Vinylidene fluoride (VDF) can be polymerized to form polyvinylidene fluoride (PVDF) through the polymerization mechanism mediated by CF2 radicals and the polymerization mechanism mediated by halogen radicals. In addition, if an additional monomer (TrFE / CTFE / HFP) is supplied, a copolymer between vinylidene fluoride and the additional monomer can be formed.

[0053]

[0054] According to one embodiment of the present invention, it is easy to form a thin film (nm thick) compared to conventional solution processes. Furthermore, it is environmentally friendly and safe because it does not use toxic solvents used in solution processes.

[0055]

[0056] And, the difficulty in initiating radical polymerization due to the electron cloud bias of vinylidene fluoride monomer is CF. m X n (X is one of Cl, Br, and I) It is solved through an initiator, and the difficulty of chemical vapor deposition due to small molecular weight is solved through a device that can form radicals while forming an ultra-low temperature for adsorption.

[0057]

[0058]

[0059] Vinylidene fluoride and CF m X nTo confirm the formation of polyvinylidene fluoride (PVDF) thin films from the initiator, multiple experiments were conducted and the results were confirmed. Table 1 shows the results of the formation of polyvinylidene fluoride according to the number of experimental runs.

[0060]

[0061] Experimental cycle Substrate temperature (℃) VDF flow rate (sccm) CF2Br2 flow rate (sccm) Chamber pressure (Torr) Time (hr) UV wavelength (nm) UV power (W) WCA (º) Thickness (nm) Other 1-5220.212544--Substrate Low 2-5220.512544--Substrate Low 3-522112544--Substrate Low 4-522312544754~5Substrate Low 5-40 ~ -1022522544705~6Substrate Low 6-40 ~ -1022522544705~6Substrate High 7-40 ~ -10220.222544886-7Substrate Low 8-40 ~ -10220.222544705~6Substrate High 9-40 ~ -1022522544905 board high

[0062] As shown in Table 1 above, the lower the substrate temperature, the more advantageous it was for the formation of polyvinylidene fluoride, and the formation of polyvinylidene fluoride and CF was better than that of vinylidene fluoride alone. m X n It can be confirmed that polyvinylidene fluoride is formed when the initiator is supplied together.

[0063]

[0064] Figure 3 is a drawing showing the water-repellent surface state on a substrate in various cases.

[0065]

[0066] Referring to Figure 3, (a) is for a simple silicon substrate, and (b) is for vinylidene fluoride and CF irradiated with UV at 5°C with a power of 4 W and a pressure of 5 torr. m X nWhen a polyvinylidene fluoride thin film was formed by supplying an initiator, (c) was irradiated with UV at a power of 4 W at -30°C and a pressure of 0.2 torr to form vinylidene fluoride and CF m X n When a polyvinylidene fluoride thin film is formed by supplying an initiator, (d) shows the water-repellent surface state on the substrate when only vinylidene fluoride is supplied by irradiating UV with a power of 24 W at -30°C and a pressure of 0.2 torr.

[0067]

[0068] As shown in Fig. 3, cases (b) and (c) can be confirmed to be water-repellent surface states generated when polyvinylidene fluoride is formed. In particular, in case (c), it can be confirmed that the water-repellent property is superior to that of (b). In contrast, in case (d) where only vinylidene fluoride is supplied, it can be seen that polyvinylidene fluoride is hardly formed because the water-repellent surface state on the substrate is weak.

[0069]

[0070] FIG. 4 is a graph showing the results of X-ray photoelectron spectroscopy (XPS) for polyvinylidene fluoride formed according to one embodiment of the present invention.

[0071]

[0072] Referring to Fig. 4, it can be confirmed that polyvinylidene fluoride is formed on the substrate by X-ray photoelectron spectroscopy.

[0073]

[0074] While representative embodiments of the present invention have been described in detail above, those skilled in the art will appreciate that various modifications to the above-described embodiments are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the claims set forth below but also by equivalents thereof.

[0075]

[0076] [Explanation of symbols]

[0077] 100: Chemical vapor deposition device

[0078] 110: Chamber

[0079] 115: Light source transmission section

[0080] 120: Susceptor

[0081] 130: UV light source

[0082] 160: Refrigerant circulation section

[0083] 171: Vinylidene fluoride (VDF) monomer gas

[0084] 172: Initiator gas

[0085] 174: Flow controller

[0086] 175: Inlet

[0087] 180: exhaust port

[0088] 190: Byproduct Treatment Department

Claims

1. In a chemical vapor deposition (CVD) device for performing chemical vapor deposition to form polyvinylidene fluoride and its copolymer on a substrate, A chamber in which a light transmitting portion is formed; A gas source supply unit for supplying vinylidene fluoride monomer gas and initiator gas to the chamber; A light source that supplies ultraviolet rays and ultraviolet light into the chamber through the light source transmitting portion; and A chemical vapor deposition apparatus for forming polyvinylidene fluoride and a copolymer thereof, comprising a susceptor positioned within the chamber, on which the substrate is mounted and in which a coolant circulation section is formed.

2. In claim 1, A chemical vapor deposition apparatus for forming polyvinylidene fluoride and a copolymer thereof, wherein at least one flow controller for controlling the flow rate of each of the vinylidene fluoride monomer gas and the initiator gas is disposed in the gas source supply unit.

3. In claim 1, The above initiator is CF m X n A chemical vapor deposition apparatus for forming polyvinylidene fluoride and its copolymer, wherein X is one of Cl, Br, and I.

4. In claim 3, A chemical vapor deposition device for forming polyvinylidene fluoride and its copolymer, wherein the chamber and the outlet are provided with a corrosion-preventing coating to prevent corrosion by the above byproduct.

5. In claim 1, A chemical vapor deposition device for forming polyvinylidene fluoride and its copolymer, wherein the above ultraviolet rays are used to form radicals in the initiator.

Images