Electrochemically fluorinated film, and preparation method therefor and use thereof

Abstract

Provided in the present invention are an electrochemically fluorinated film, and a preparation method therefor and the use thereof. Specifically, the component of the electrochemically fluorinated film is aluminum fluoride, and the aluminum fluoride in the electrochemically fluorinated film is exclusively of a body-centered cubic structure. In the preparation process of the electrochemically fluorinated film of the present invention, the surface temperature of an aluminum alloy is close to 3400-3600 K, and the prepared electrochemically fluorinated film undergoes glazing at the high temperature, thereby making the prepared electrochemically fluorinated film more uniform. The electrochemically fluorinated film of the present invention is uniform and dense, and exhibits good appearance. When an aluminum alloy comprises the electrochemically fluorinated film of the present invention on the surface, the acceptance rate of color variation on the surface can be improved, and cleaning costs can be reduced. The halogen corrosion resistance of the aluminum alloy comprising the electrochemically fluorinated film of the present invention on the surface can be improved. The withstand voltage of the aluminum alloy comprising the electrochemically fluorinated film of the present invention on the surface can be increased.

Description

Electrochemical fluorinated film, preparation method and application thereof TECHNICAL FIELD

[0001] The present application belongs to the field of aluminum alloy surface treatment, and particularly relates to an electrochemical fluorinated film, a preparation method and application thereof. BACKGROUND

[0002] In the prior art, aluminum alloy parts in the cavity of PECVD, PEALD and other equipment will be eroded by F ions in the process. The existing scheme is to dissociate F ions by F-containing gas in PECVD, PEALD and other equipment, and the F ions react with the aluminum alloy parts in situ to grow a fluorinated layer in a high-temperature sealed environment, so as to use the fluorinated layer as a protective layer against F ion erosion. The reaction of this method takes about 48-72 hours to obtain a 5 μm thick film, and the fluorination process needs to be kept at high temperature and ionized F-containing gas for a long time, so the resource consumption is extremely large. This method has extremely high requirements for the pretreatment process of aluminum alloy, and the residual amount of some metal elements on the surface of the aluminum alloy needs to be less than 100*10 10 atoms / cm 2 In addition, the in-situ fluorinated film layer is not dense, has poor resistance to halogen element erosion, and low breakdown voltage. SUMMARY

[0003] The present application provides an electrochemical fluorinated film, a preparation method and application thereof.

[0004] In a first aspect, the present application provides an electrochemical fluorinated film, wherein the electrochemical fluorinated film is composed of aluminum fluoride, and the aluminum fluoride in the electrochemical fluorinated film is entirely in a body-centered cubic structure.

[0005] In one or more embodiments, the X-ray diffraction (XRD) pattern of the electrochemical fluorinated film has characteristic peaks at 2θ angles of 25.9°±0.2°, 37.5°±0.2° and 44.9°±0.2°.

[0006] In one or more embodiments, the X-ray diffraction (XRD) pattern of the electrochemical fluorinated film has characteristic peaks at one or more of 2θ angles of 38.1°±0.2°, 43.5°±0.2° and 52.7°±0.2°; preferably, the X-ray diffraction (XRD) pattern of the electrochemical fluorinated film has a characteristic peak at a 2θ angle of 57.4°±0.2°.

[0007] In one or more embodiments, the X-ray diffraction (XRD) pattern of the electrochemical fluorinated film has characteristic peaks at 2θ angles shown in Table 1.

[0008] In one or more embodiments, the electrochemical fluorinated film has an X-ray diffraction (XRD) pattern as shown in FIG. 1.

[0009] In one or more embodiments, the electrochemically fluorinated film has a thickness of ≤ 30 μm; preferably, the electrochemically fluorinated film has a thickness of 5-15 μm.

[0010] In a second aspect of the present application, there is provided a method for preparing an electrochemically fluorinated film, the method comprising the steps of: providing an electrolyte having a solute of a fluorine salt, the fluorine salt comprising ammonium fluoride and optionally other fluorine salts, connecting an aluminum alloy as an anode to a power source, and preparing the electrochemically fluorinated film on the surface of the aluminum alloy by electrochemical fluorination, the concentration of fluorine ions in the electrolyte being 30-170 g / L.

[0011] In one or more embodiments, the electrochemically fluorinated magnesium prepared by the method is the electrochemically fluorinated film as described in the first aspect of the present application.

[0012] In one or more embodiments, the method has one or more of the following features:

[0013] the electrochemical fluorination is performed for a time of 60-120 min;

[0014] the electrochemical fluorination is performed at a current density of 8-30 A;

[0015] the electrochemical fluorination is performed at a negative current density of 0-10 A;

[0016] the electrochemical fluorination is performed at a frequency of 50-1500 HZ;

[0017] the electrochemical fluorination is performed at a duty cycle of 5-70%.

[0018] In one or more embodiments, the other fluorine salt is selected from one or both of potassium fluoride and sodium fluoride.

[0019] In one or more embodiments, the solvent of the electrolyte is selected from one or both of ethanol and ethylene glycol.

[0020] In one or more embodiments, the ethanol and ethylene glycol have a purity of ≥ 99%.

[0021] In one or more embodiments, the temperature of the electrolyte is 0-15 °C; and / or, the conductivity of the electrolyte is 4-8 mS / cm.

[0022] In one or more embodiments, the method has one or more of the following features:

[0023] the power source is a micro-arc power source;

[0024] the aluminum alloy is selected from a 1-series aluminum alloy, a 3-series aluminum alloy, a 5-series aluminum alloy, and a 6-series aluminum alloy;

[0025] The cathode is stainless steel, titanium alloy or graphite.

[0026] In a third aspect of the present application, there is provided a method for improving the breakdown voltage and / or halogen resistance of an aluminum alloy part, the method comprising the step of preparing the electrochemical fluorination film according to the first aspect of the present application on the surface of the aluminum alloy part; or, the method comprising the step of preparing an electrochemical fluorination film on the surface of the aluminum alloy part using the method according to the second aspect of the present application.

[0027] In one or more embodiments, the aluminum alloy part is a semiconductor equipment in-cavity component.

[0028] In one or more embodiments, the semiconductor equipment is PECVD or PEALD.

[0029] In a fourth aspect of the present application, there is provided an aluminum alloy part having a surface comprising the electrochemical fluorination film according to the first aspect of the present application, or an aluminum alloy part having a surface comprising an electrochemical fluorination film prepared using the method according to the second aspect of the present application.

[0030] In one or more embodiments, the aluminum alloy part is a semiconductor equipment in-cavity component.

[0031] In one or more embodiments, the semiconductor equipment is PECVD or PEALD.

[0032] In a fifth aspect of the present application, there is provided the use of the electrochemical fluorination film according to the first aspect of the present application or the electrochemical fluorination film prepared using the method according to the second aspect of the present application for improving the halogen resistance of an aluminum alloy part; and / or, the use of the electrochemical fluorination film according to the first aspect of the present application or the electrochemical fluorination film prepared using the method according to the second aspect of the present application for improving the breakdown voltage of an aluminum alloy part. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 is an XRD pattern of the electrochemical fluorination film prepared in Example 1.

[0034] Figure 2 is an XRD pattern of the in-situ fluorination film prepared in Comparative Example 1.

[0035] Figure 3 is an SEM image of the surface morphology of the electrochemical fluorination film prepared in Example 1.

[0036] Figure 4 is an SEM image of the cross-sectional morphology of the electrochemical fluorination film prepared in Example 1, wherein a-resin, b-electrochemical fluorination film, c-aluminum alloy.

[0037] Figure 5 is an SEM image of the surface morphology of the in-situ fluorination film prepared in Comparative Example 1.

[0038] Figure 6 is a SEM image of the cross-sectional morphology of the in-situ fluorinated film prepared in Comparative Example 1, wherein d - resin, e - in-situ fluorinated film, f - aluminum alloy.

[0039] Figure 7 is a schematic diagram of the apparatus for preparing the electrochemical fluorinated film on the surface of the aluminum alloy in one or more embodiments of the present application; wherein A - aluminum alloy, B - electrolyte, C - micro-arc power supply, D - water chiller, E - anode, F - cathode.

[0040] Figure 8 is a voltage change curve during the preparation of the electrochemical fluorinated film on the surface of the aluminum alloy, wherein the abscissa is time (h) and the ordinate is voltage (V).

[0041] Figure 9 is a photograph of the appearance of the electrochemical fluorinated film prepared in Example 1.

[0042] Figure 10 is a photograph of the appearance of the in-situ fluorinated film prepared in Comparative Example 1.

[0043] Figure 11 is a schematic diagram of the method for testing the resistance to hydrochloric acid corrosion in Test Example 1; wherein 1 - hydrochloric acid, 2 - test tube, 3 - adhesive, 4 - aluminum alloy test block.

[0044] Figure 12 is a schematic diagram of the apparatus for testing the breakdown voltage resistance in Test Example 2. DETAILED DESCRIPTION

[0045] In order for those skilled in the art to understand the features and effects of the present application, the following is a general description and definition of the terms and phrases mentioned in the specification and claims. Unless otherwise specified, all technical and scientific words used herein have their usual meanings to those skilled in the art of the present application, and in the event of conflict, the definitions in the present specification shall prevail.

[0046] Theories or mechanisms described and disclosed herein, whether correct or not, should not be considered limiting on the scope of the present application, i.e., the present application can be implemented without regard to any particular theory or mechanism.

[0047] In this document, "comprise", "include", "contain", and similar words are intended to cover the meanings of "consist essentially of" and "consist of", e.g., when this document discloses that "A comprises B and C", "A consists essentially of B and C" and "A consists of B and C" should be considered to have been disclosed herein.

[0048] In this document, all features defined by numerical ranges or percentage ranges, such as values, amounts, contents and concentrations, are intended to be merely for the sake of brevity and convenience. Accordingly, the description of the numerical range or percentage range should be considered to have encompassed and specifically disclosed all possible sub-ranges and individual values within the range (including integers and fractions).

[0049] Herein, unless otherwise specifically indicated, percentages are in mass percent and ratios are mass ratios.

[0050] Herein, when describing embodiments or examples, it is to be understood that the invention is not limited to these embodiments or examples. Rather, all alternatives, modifications and equivalents of the methods and materials described herein, which would be apparent to one skilled in the art, are included within the scope of the invention.

[0051] Herein, in order to make the description simple, all possible combinations of the technical features in each embodiment or example are not described. Therefore, as long as the combinations of the technical features do not contradict each other, the technical features in each embodiment or example can be combined arbitrarily, and all possible combinations should be considered as the scope described in the specification.

[0052] In the present invention, an electrochemical fluorination film is prepared on the surface of an aluminum alloy by a method of electrolysis of the aluminum alloy as an anode in an electrolyte containing fluoride ions.

[0053] In the present invention, the aluminum alloy placed as an anode undergoes an oxidation reaction under the action of a power source, and the surface of the aluminum alloy is etched, i.e., Al atoms on the surface of the aluminum alloy are oxidized to Al 3+ into the electrolyte, and AlF3is produced at the moment of contact with fluoride ions in the electrolyte, and deposited on the surface of the aluminum alloy to form an electrochemical fluorination film.

[0054] Electrochemical fluorination film

[0055] The present invention provides an electrochemical fluorination film, the composition of which is aluminum fluoride, and all of the aluminum fluoride in the electrochemical fluorination film is of a body-centered cubic structure. In the preparation process of the electrochemical fluorination film, the prepared electrochemical fluorination film is vitrified at high temperature (3400-3600 K), so that the prepared electrochemical fluorination film is uniform and dense.

[0056] The present invention provides an electrochemical fluorination film, the X-ray diffraction (XRD) pattern of which has characteristic peaks at at least 3, at least 4, at least 5, at least 6 or all 7 of the following 2θ angles: 25.9°±0.2°, 37.5°±0.2°, 38.1°±0.2°, 43.5°±0.2°, 44.9°±0.2°, 52.7°±0.2° and 57.4°±0.2°.

[0057] In some embodiments, the electrochemically fluorinated film of the present application has characteristic peaks at least at the following 2-theta angles: 25.9° ± 0.2°, 37.5° ± 0.2° and 44.9° ± 0.2°, and optionally at least one, at least two, at least three or all four of the following 2-theta angles: 38.1° ± 0.2°, 43.5° ± 0.2°, 52.7° ± 0.2° and 57.4° ± 0.2°.

[0058] In some embodiments, the electrochemically fluorinated film of the present application has characteristic peaks at least at the following 2-theta angles: 25.9° ± 0.2°, 37.5° ± 0.2° and 44.9° ± 0.2°, and at least one, at least two or all three of the following 2-theta angles: 38.1° ± 0.2°, 43.5° ± 0.2° and 52.7° ± 0.2°, and optionally at 57.4° ± 0.2°.

[0059] The XRD pattern of the electrochemically fluorinated film of the present application is shown in Figure 1.

[0060] The XRD pattern analysis data of the electrochemically fluorinated film of the present application is shown in Table 1.

[0061] Table 1

[0062] In some embodiments, the electrochemically fluorinated film of the present application has a thickness of ≤ 30 μm, such as 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm. In some embodiments, the electrochemically fluorinated film of the present application has a thickness of 5-15 μm. The electrochemically fluorinated film of the present application can have a thickness of 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, or between any two of these values. In some embodiments, the thickness of the electrochemically fluorinated film is adjusted by adjusting the time of electrolysis. The longer the time of electrolysis, the greater the thickness of the electrochemically fluorinated film.

[0063] Method for preparing an electrochemically fluorinated film

[0064] The present application provides a method for preparing an electrochemically fluorinated film, the method comprising the steps of: providing an electrolyte with a solute of a fluorine salt, the fluorine salt comprising ammonium fluoride and optionally other fluorine salts, connecting an aluminum alloy as an anode to a power source, and preparing an electrochemically fluorinated film on the surface of the aluminum alloy by electrochemical fluorination, the concentration of fluoride ions in the electrolyte being 30-170 g / L.

[0065] In some embodiments, the other fluoride salt is selected from one or both of potassium fluoride and sodium fluoride. Preferably, the other fluoride salt is potassium fluoride and sodium fluoride. In some embodiments, the fluoride salt is ammonium fluoride, potassium fluoride and sodium fluoride.

[0066] In some embodiments, the solvent of the electrolyte is selected from one or both of ethanol and ethylene glycol. Preferably, the solvent is a mixed solvent of ethanol and ethylene glycol. Ethanol and ethylene glycol are analytical alcohols. The purity of ethanol and ethylene glycol is ≥99%. Herein, the "purity" refers to the mass fraction of a specific component, for example, the purity of ethanol refers to the mass fraction of ethanol in the purchased ethanol reagent. Since ethylene glycol itself is a coolant, using a mixed solution of ethylene glycol and ethanol as the solvent of the electrolyte is more conducive to temperature control of the electrolyte.

[0067] In some embodiments, the concentration of fluoride ions in the electrolyte is 30-170 g / L, for example, 40 g / L, 50 g / L, 60 g / L, 70 g / L, 80 g / L, 90 g / L, 100 g / L, 110 g / L, 120 g / L, 130 g / L, 140 g / L, 150 g / L, 160 g / L, 170 g / L, or between any two numerical values. The electrolyte contains sufficient fluoride ions, and the electrolyte can achieve continuous fluorination, effectively improve the efficiency of preparing electrochemical fluorination film, increase the yield of the prepared electrochemical fluorination film, and reduce resource consumption. After a period of electrolysis, the concentration of fluoride ions in the electrolyte decreases. In order to ensure that the concentration of fluoride ions in the electrolyte meets the conditions of electrolysis, the concentration of fluoride ions in the electrolyte can be monitored in real time.

[0068] In order to ensure the efficient progress of electrolysis, it is necessary to control the conductivity of the electrolyte. The conductivity of the electrolyte can be 4-8 mS / cm, for example, 4 mS / cm, 5 mS / cm, 6 mS / cm, 7 mS / cm, 8 mS / cm, or between any two numerical values. The conductivity of ethylene glycol at 25°C is only 0.2 mS / cm, and the conductivity of ethanol at 25°C is only 1.35*10 -6 mS / cm, therefore, the conductivity of the electrolyte can be controlled by controlling the concentration of fluoride salt in the electrolyte to be within a suitable range.

[0069] In some embodiments, the electrolyte comprises 1 L of solvent and fluoride salts, the fluoride salts comprising 40-100 g of ammonium fluoride, 20-150 g of potassium fluoride, and 10-150 g of sodium fluoride. Preferably, the mass of ammonium fluoride added in 1 L of electrolyte can be 50 g, 60 g, 70 g, 80 g, 90 g, 100 g, or between any two of the numerical values. Preferably, the mass of potassium fluoride added in 1 L of electrolyte can be 30 g, 40 g, 50 g, 60 g, 70 g, 80 g, 90 g, 100 g, 110 g, 120 g, 130 g, 140 g, 150 g, or between any two of the numerical values. Preferably, the mass of sodium fluoride added in 1 L of electrolyte can be 20 g, 30 g, 40 g, 50 g, 60 g, 70 g, 80 g, 90 g, 100 g, 110 g, 120 g, 130 g, 140 g, 150 g, or between any two of the numerical values. In some embodiments, the electrolyte comprises 1 L of solvent and fluoride salts, the fluoride salts comprising 40-50 g of ammonium fluoride, 15-30 g of potassium fluoride, and 10-30 g of sodium fluoride. In some embodiments, the electrolyte comprises 1 L of solvent and fluoride salts, the fluoride salts comprising 80-100 g of ammonium fluoride, 30-80 g of potassium fluoride, and 40-90 g of sodium fluoride.

[0070] In some embodiments, the power source is a micro-arc power source.

[0071] In some embodiments, the aluminum alloy is selected from the group consisting of 1 series aluminum alloy (e.g., 1050 aluminum alloy), 3 series aluminum alloy (e.g., 3003 aluminum alloy), 5 series aluminum alloy (e.g., 5083 aluminum alloy), and 6 series aluminum alloy (e.g., 6061 aluminum alloy). Preferably, the aluminum alloy is 1050 aluminum alloy among the 1 series aluminum alloy.

[0072] In some embodiments, the cathode is stainless steel, titanium alloy, or graphite. Preferably, the cathode is stainless steel.

[0073] In some embodiments, the temperature of the electrolyte is 0-15℃, such as 1℃, 3℃, 5℃, 10℃, 12℃, 15℃, or between any two of the numerical values. In some embodiments, the temperature of the electrolyte is 5-15℃. The temperature of the electrolyte affects the film layer growth rate and film layer appearance of the electrochemical fluorinated film. When the temperature of the electrolyte is lower than 0℃, the electrolysis efficiency is low, and the electrolysis reaction is slow to the extent that the film cannot be normally grown. When the temperature of the electrolyte is higher than 15℃, the film layer appearance of the electrochemical fluorinated film becomes rough, and the number of micropores of the electrochemical fluorinated film increases.

[0074] In some embodiments, the electrochemical fluorination is performed for a time period of 60-120 min, such as 70 min, 80 min, 90 min, 100 min, 110 min, 120 min, or a range between any two of these values. Preferably, the electrochemical fluorination is performed for a time period of 90-120 min.

[0075] In some embodiments, the electrochemical fluorination is performed at a current density of 8-30 A, such as 10 A, 15 A, 20 A, 25 A, 30 A, or a range between any two of these values. Preferably, the electrochemical fluorination is performed at a current density of 8-15 A.

[0076] In some embodiments, the electrochemical fluorination is performed at a negative current density of 0-10 A, such as 0.01 A, 0.05 A, 0.1 A, 0.15 A, 0.2 A, 0.5 A, 1 A, 2 A, 3 A, 5 A, 8 A, 10 A, or a range between any two of these values. In some embodiments, the electrochemical fluorination is performed at a negative current density of 0.01-0.2 A or 0.05-0.1 A.

[0077] In some embodiments, the electrochemical fluorination is performed at a frequency of 50-1500 HZ, such as 60 HZ, 80 HZ, 100 HZ, 150 HZ, 200 HZ, 300 HZ, 500 HZ, 800 HZ, 1000 HZ, 1200 HZ, 1500 HZ, or a range between any two of these values. In some embodiments, the electrochemical fluorination is performed at a frequency of 50-200 HZ or 90-110 HZ.

[0078] In some embodiments, the electrochemical fluorination is performed at a duty cycle of 5-70%, such as 8%, 10%, 12%, 15%, 16%, 18%, 20%, 30%, 40%, 50%, 60%, 70%, or a range between any two of these values. In some embodiments, the electrochemical fluorination is performed at a duty cycle of 10-30% or 15-20%.

[0079] In some embodiments, the method further comprises a step of pre-treating the aluminum alloy before placing it on the anode of the power source. In some embodiments, the pre-treatment comprises one or more of polishing, removing grease and floating dust, ultrasonic removal of chemical residue, and oven drying to remove water vapor residue. In some embodiments, the pre-treatment comprises polishing, removing grease and floating dust, ultrasonic removal of chemical residue, and oven drying to remove water vapor residue, in that order.

[0080] In some embodiments, the aluminum alloy with the electrochemically fluorinated film is cleaned and dried. The cleaning can be ultrasonic cleaning. The drying can be by CDA purging and / or oven drying.

[0081] In some embodiments, the electrochemical fluorinated film of the present application is prepared using the method of the present application.

[0082] Apparatus

[0083] The method of the present application for preparing the electrochemical fluorinated film is carried out by electrolysis. Therefore, the present application provides an electrolysis apparatus for use in the method of the present application. The apparatus comprises a power source, an electrolytic cell, an electrolyte in the electrolytic cell, an anode and a cathode disposed in the electrolytic cell in sufficient contact with the electrolyte, a chiller connected to the electrolytic cell for cooling the electrolyte, and a circuit connecting the anode and the power source, and the cathode and the power source. In some embodiments, the power source, the anode, the cathode, and the electrolyte are as described in any of the embodiments herein. The chiller is used to cool the electrolyte to ensure that the temperature of the electrolyte is in the range of 0-15°C.

[0084] As shown in Figure 7, after the apparatus is installed, the power source, preferably a micro-arc power source, is turned on to carry out the electrolysis reaction. When the anode is an aluminum alloy piece and the electrolyte is rich in fluoride ions (for example, the concentration of fluoride ions in the electrolyte is 30-170 g / L), the electrochemical fluorinated film can be prepared on the surface of the aluminum alloy piece after the electrolysis reaction is completed.

[0085] Method for improving the breakdown voltage and / or halogen resistance of an aluminum alloy piece

[0086] The method of the present application for preparing the electrochemical fluorinated film produces the electrochemical fluorinated film of the present application on the surface of an aluminum alloy. The electrochemical fluorinated film is dense in structure and has the effect of improving the halogen resistance of the aluminum alloy. Therefore, the present application provides a method for improving the halogen resistance of an aluminum alloy piece. The method comprises the step of preparing the electrochemical fluorinated film of the present application on the surface of the aluminum alloy piece.

[0087] The electrochemical fluorinated film produced by the method of the present application for preparing the electrochemical fluorinated film is dense in structure and can effectively improve the breakdown voltage of the aluminum alloy. Therefore, the present application provides a method for improving the breakdown voltage of an aluminum alloy piece. The method comprises the step of preparing the electrochemical fluorinated film of the present application on the surface of the aluminum alloy piece.

[0088] In some embodiments, the aluminum alloy piece is a component inside a cavity of a semiconductor device. Preferably, the semiconductor device is a PECVD or PEALD.

[0089] Aluminum alloy having a surface comprising an electrochemical fluorinated film

[0090] The present application provides an aluminum alloy piece having a surface comprising the electrochemical fluorinated film of the present application. In some embodiments, the aluminum alloy piece is a component inside a cavity of a semiconductor device. Preferably, the semiconductor device is a PECVD or PEALD.

[0091] Applications

[0092] The present application provides the use of the electrochemical fluorination film of the present application in improving the resistance of aluminum alloy parts to halogen element corrosion. In some embodiments, the halogen element is selected from one or more of fluoride ions, chloride ions, bromide ions, and iodide ions. Preferably, the halogen element is selected from one or both of fluoride ions and chloride ions.

[0093] The present application provides the use of the electrochemical fluorination film of the present application in improving the breakdown voltage resistance of aluminum alloy parts. The breakdown voltage resistance of aluminum alloy parts with the electrochemical fluorination film of the present application on the surface is between 450-550V, for example between 450-500V.

[0094] In some embodiments, the aluminum alloy part is as described in any of the embodiments herein.

[0095] The present application has the following advantages:

[0096] (1) In the process of preparing the electrochemical fluorination film of the present application, the surface temperature of the aluminum alloy is close to 3400-3600K, and the prepared electrochemical fluorination film is glaze at this high temperature, making the prepared electrochemical fluorination film more uniform.

[0097] (2) The electrochemical fluorination film is uniform and dense, and has a good appearance. The aluminum alloy with the electrochemical fluorination film on the surface can improve the appearance color difference yield and reduce the cleaning cost.

[0098] (3) The aluminum alloy with the electrochemical fluorination film of the present application on the surface can improve the resistance to halogen element corrosion.

[0099] (4) The aluminum alloy with the electrochemical fluorination film of the present application on the surface can improve the breakdown voltage resistance.

[0100] (5) In the preparation method of the electrochemical fluorination film of the present application, the film forming process is accompanied by high temperature ceramicization of the film layer on the surface of the aluminum alloy, so the present application method has very low requirements for the cleanliness of the aluminum alloy before preparing the electrochemical fluorination film.

[0101] (6) The in-situ fluorination time is close to 100 hours, which consumes a lot of resources; while the time for preparing the electrochemical fluorination film of the present application method only needs 1-2 hours, greatly reducing the energy consumption.

[0102] (7) Compared with the in-situ fluorination method, the present application method can realize large-scale production of the electrochemical fluorination film on the surface of the aluminum alloy part.

[0103] The present application will be further described in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present application and not to limit the scope of the present application. The experimental methods in the following examples are not specified, which are usually carried out under conventional conditions, or under the conditions recommended by the manufacturer. Unless otherwise specified, percentages and parts are calculated by weight.

[0104] The thickness of the fluorinated film on the surface of the aluminum alloy was measured using an eddy current film thickness gauge. The test principle of the eddy current film thickness gauge is as follows: a high-frequency alternating current signal generates an electromagnetic field in the probe coil, and when the probe is close to the conductor, an eddy current is formed therein. The closer the probe is to the conductive base, the greater the eddy current and the greater the reflected impedance. This feedback effect represents the distance between the probe and the conductive base, that is, the thickness of the non-conductive coating (i.e., the fluorinated film) on the conductive base (i.e., the aluminum alloy).

[0105] The concentration of fluoride ions in the electrolyte was tested using ion selective method by a fluoride ion sensor (manufacturer: Anhui Maideshi Environmental Protection Technology Co., Ltd.; model: MDS-F0032). In the measurement process of ion selective method, the sensor is placed in the solution, and the ions in the solution will undergo selective adsorption or ion exchange reaction with the chemical complex in the membrane through the ion sensitive layer. These reactions cause changes in the charge distribution at the interface, which in turn causes changes in the electric potential. The change in the electric potential can be used to calculate the concentration of the target ion in the solution. At this time, the difference between the potential of the measuring electrode and the potential of the reference electrode is positively correlated with the ion concentration.

[0106] The conductivity of the electrolyte was tested using four-wire graphite electrode method by a conductivity sensor (manufacturer: Anhui Maideshi Environmental Protection Technology Co., Ltd.; model: MDS-WRY-EC). In the measurement process of four-wire graphite electrode method, the conductivity sensor is placed in the solution, and the ions in the solution will move under the action of the electric field and collide with other ions. In this way, an electric current is formed between the ions in the solution. The current intensity is related to the number and flow velocity of the ions in the solution, and the flow velocity is related to the size of the potential difference and the movement rate of the ions in the solution. Therefore, by measuring the current intensity and the size of the potential difference, the conductivity of the solution can be obtained. Specifically, there are two pairs of electrodes in the instrument, namely the measuring electrode and the reference electrode. The measuring electrode passes through the solution to flow a current, while the reference electrode is separated from the solution by a certain distance and does not directly contact the solution, and is used to measure the potential difference. The conductivity meter will compensate for the capacitance between the electrodes by changing the frequency of the alternating current. This is because the capacitance will affect the potential difference, especially for high conductivity solutions. Through the calculation of the Schmacher equation, the conductivity values at different frequencies can be obtained, and then the variation law of the conductivity with temperature and concentration can be obtained.

[0107] Example 1, Preparation of Electrochemical Fluorinated Film

[0108] Step 1, aluminum alloy test block pretreatment: 1050 aluminum alloy test block with a size of 50mm*50mm*5mm, polished with 320# sandpaper + red melon cloth (scouring pad), cleaned with chemical degreaser (Isoprep49L, MDM Technology (Suzhou) Co., Ltd.) to remove grease and dust, then cleaned with pure water to remove chemical residues, then dried with compressed air, and then heated and dried to remove water vapor residues for standby.

[0109] Step 2, preparation of electrolyte: 500ml ethanol (purity 99.7%) and 1500ml ethylene glycol (purity 99.7%) as solvent, 100g ammonium fluoride, 50g potassium fluoride and 60g sodium fluoride as fluorine source, the conductivity of the electrolyte is 5.32mS / cm.

[0110] Step 3, electrochemical fluorination: the aluminum alloy pretreated in step 1 is placed in the anode of the micro-arc power supply, and the cathode plate material is stainless steel. The parameters of the electrochemical fluorination process are: current density is 10A, negative current density is 0.1A, frequency is 100HZ, duty cycle is 18%, electrolyte temperature is 10℃, and growth time is 120min. Electrolysis is carried out under constant current conditions. As the electrolysis proceeds, the electrochemical fluorination film gradually grows on the surface of the aluminum alloy, causing the resistance of the aluminum alloy surface to rise, and the electrolysis voltage to rise accordingly. The voltage change curve during the preparation of the electrochemical fluorination film is shown in Figure 8. The aluminum alloy after the electrochemical fluorination film is prepared is cleaned with pure water ultrasonic cleaning, CDA purging, and oven drying. The appearance of the electrochemical fluorination film of the aluminum alloy prepared by the method of this embodiment is shown in Figure 9. The thickness of the electrochemical fluorination film prepared in this embodiment is 5μm. Due to the small area of the aluminum alloy test block, the conductivity and fluoride ion concentration of the electrolyte measured by the instrument do not change after electrolysis.

[0111] Comparative Example 1, preparation of in-situ fluorination film

[0112] The aluminum alloy test block pretreated in step 1 of Example 1 is placed in the vacuum chamber of the PECVD equipment, the chamber is heated to 400℃, after the temperature is stable, 4000sccm of NF3 and 8000sccm of Ar are introduced, and the aluminum alloy test block is in-situ fluorinated for 48h under the action of plasma, and the chamber pressure is controlled at 6torr.

[0113] The appearance of the prepared in-situ fluorination film is shown in Figure 10, and the thickness of the in-situ fluorination film prepared in this comparative example is 5μm. The circle is a non-uniform defect, and when testing the fluorination film thickness at the circle, the eddy current film thickness meter cannot measure the value at the defect.

[0114] Characterization of electrochemical fluorination film and in-situ fluorination film

[0115] 1. XRD characterization

[0116] The XRD pattern of the electrochemically fluorinated film prepared in Example 1 is shown in Figure 1. The XRD pattern of the in-situ fluorinated film prepared in Comparative Example 1 is shown in Figure 2. The XRD data of the electrochemically fluorinated film prepared in Example 1 is shown in Table 1. The XRD data of the in-situ fluorinated film prepared in Comparative Example 1 is shown in Table 2.

[0117] Table 2

[0118] 2. SEM characterization of the surface and cross-section of the electrochemically fluorinated film and the in-situ fluorinated film

[0119] The aluminum alloy containing the electrochemically fluorinated film on the surface and the aluminum alloy containing the in-situ fluorinated film on the surface were subjected to sample cutting, resin embedding, mechanical polishing, and rinsing, and the prepared samples were subjected to SEM characterization. The SEM image of the surface morphology of the electrochemically fluorinated film prepared in Example 1 is shown in Figure 3. The SEM image of the cross-section morphology of the aluminum alloy containing the electrochemically fluorinated film on the surface is shown in Figure 4. The SEM image of the surface morphology of the in-situ fluorinated film prepared in Comparative Example 1 is shown in Figure 5. The SEM image of the cross-section morphology of the aluminum alloy containing the in-situ fluorinated film on the surface is shown in Figure 6. The a layer (the part in the rectangular frame) in Figure 4 and the d layer (the part in the rectangular frame) in Figure 6 are both the resin introduced on the surface of the electrochemically fluorinated film and the in-situ fluorinated film when the SEM sample was prepared. The b layer (the part in the rectangular frame) in Figure 4 is the electrochemically fluorinated film; the c layer (the part below the rectangular frame) is the aluminum alloy. The e layer (the part in the rectangular frame) in Figure 6 is the in-situ fluorinated film. The f layer (the part below the rectangular frame) is the aluminum alloy.

[0120] As can be seen from the comparison of Figure 3 and Figure 5, and the comparison of the b layer and the e layer, compared with the electrochemically fluorinated film, the in-situ fluorinated film has many defects and pores on the surface and cross-section, and the film layer is not dense and uniform.

[0121] Test Example 1, halogen element corrosion resistance test

[0122] Step 1. Take the aluminum alloy containing the electrochemically fluorinated film prepared in Example 1 and the aluminum alloy containing the in-situ fluorinated film prepared in Comparative Example 1, and select a test area in the area 10 mm away from the edge. Seal one end of the test tube to the test area of the electrochemically fluorinated film and the in-situ fluorinated film, and use adhesive to seal the tube, which should be waterproof, acid-resistant, and leak-proof. The test tube described above is a glass tube with a diameter of 15 mm and a length of at least 25 mm, and the end face is cut flat, as shown in Figure 11.

[0123] Step 2. Use 5% by weight of hydrochloric acid, which is prepared on site.

[0124] Step 3. Pour the prepared hydrochloric acid into the test tube bonded to the aluminum alloy test block, and the height of the hydrochloric acid should be at least 15 mm, and at the same time, start the timer.

[0125] Step 4, the process of hydrochloric acid etching film layer will not produce bubbles, when the hydrochloric acid contacts with bare aluminum, it will produce obvious hydrogen bubbles, the failure feature is that more than 3 bubbles appear continuously within 1 second in the fluorinated film test area. After the above features appear, the timer is closed, and the time length is recorded. The failure time of in-situ fluorinated film is 2h, and the failure time of electrochemical fluorinated film is 3h.

[0126] Test Example 2, breakdown voltage test

[0127] Step 1, take the aluminum alloy with electrochemical fluorinated film prepared in Example 1 and the aluminum alloy with in-situ fluorinated film prepared in Comparative Example 1. Connect the above two fluorinated film containing aluminum alloy test blocks with the breakdown voltage tester (Huayi Electronics SE 7440) through the cable to form a circuit, see Figure 12.

[0128] Step 2, start the tester, after the test is completed, the equipment is automatically closed and the corresponding data results are displayed, the breakdown voltage of the in-situ fluorinated layer is 194V, and the breakdown voltage of the electrochemical fluorinated layer with the same film thickness is 480V.

Claims

1. An electrochemical fluorination membrane characterized by, The electrochemical fluorination film is composed of aluminum fluoride, and all the aluminum fluoride in the electrochemical fluorination film is in a body-centered cubic structure.

2. The electrochemical fluorination membrane of claim 1 wherein, The X-ray diffraction (XRD) pattern of the electrochemical fluorination film has characteristic peaks at 2θ angles of 25.9°±0.2°, 37.5°±0.2°, and 44.9°±0.2°.

3. The electrochemical fluorination membrane of claim 2 wherein, The X-ray diffraction (XRD) pattern of the electrochemical fluorination film has one or more characteristic peaks at 2θ angles of 38.1°±0.2°, 43.5°±0.2°, and 52.7°±0.2°; preferably, the X-ray diffraction (XRD) pattern of the electrochemical fluorination film has a characteristic peak at a 2θ angle of 57.4°±0.2°.

4. The electrochemical fluorination membrane of claim 1 wherein, The X-ray diffraction (XRD) pattern of the electrochemical fluorination film has characteristic peaks at 2θ angles shown in Table 1.

5. The electrochemical fluorination membrane of claim 1 wherein, The electrochemical fluorination film has an X-ray diffraction (XRD) pattern as shown in FIG.

1.

6. The electrochemical fluorination membrane as set forth in any one of claims 1 to 5 wherein, The electrochemical fluorination film has a thickness of ≤30 μm; preferably, the electrochemical fluorination film has a thickness of 5-15 μm.

7. A method of preparing an electrochemical fluorination membrane characterized by, The method comprises the steps of: providing an electrolyte with a solute of a fluorine salt, the fluorine salt comprising ammonium fluoride and optionally other fluorine salts, connecting an aluminum alloy as an anode to a power source, and preparing the electrochemical fluorination film on the surface of the aluminum alloy by electrochemical fluorination, the concentration of fluorine ions in the electrolyte being 30-170 g / L.

8. The method of claim 7, wherein, The method has one or more of the following characteristics: The electrochemical fluorination time is 60-120 min; The electrochemical fluorination current density is 8-30 A; The electrochemical fluorination negative current density is 0-10 A; The electrochemical fluorination frequency is 50-1500 HZ; The electrochemical fluorination duty cycle is 5-70%.

9. The method of claim 7, wherein, The other fluorine salt is selected from one or both of potassium fluoride and sodium fluoride; and / or, the solvent of the electrolyte is selected from one or both of ethanol and ethylene glycol, preferably, the purity of ethanol and ethylene glycol is ≥99%.

10. The method of claim 7, wherein, The temperature of the electrolyte is 0-15 °C; and / or, the conductivity of the electrolyte is 4-8 mS / cm.

11. The method of claim 7, wherein, The method has one or more of the following characteristics: The power source is a micro-arc power source; The aluminum alloy is selected from 1-series aluminum alloys, 3-series aluminum alloys, 5-series aluminum alloys, and 6-series aluminum alloys; The cathode is stainless steel, titanium alloy, or graphite.

12. The method of claim 7, wherein, The electrochemical fluorination film is the electrochemical fluorination film according to any one of claims 1-6.

13. A method for improving the withstand voltage and / or the resistance to halogen elements of an aluminium alloy piece, characterized in that, The method comprises the step of: preparing the electrochemical fluorination film according to any one of claims 1-6 on the surface of the aluminum alloy piece; Preferably, the aluminum alloy piece is a semiconductor equipment in-cavity component; preferably, the semiconductor equipment is PECVD or PEALD.

14. An aluminum alloy piece having a surface comprising the electrochemical fluorination film according to any one of claims 1-6; preferably, the aluminum alloy piece is a semiconductor equipment in-cavity component; preferably, the semiconductor equipment is PECVD or PEALD.

15. Use of the electrochemical fluorination film of any one of claims 1-6 to improve the resistance of an aluminum alloy piece to halogen element attack; and / or, use of the electrochemical fluorination film of any one of claims 1-6 to improve the breakdown voltage resistance of an aluminum alloy piece.

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