JP3995546B2 - Metal material with metal oxyfluoride coating - Google Patents

Description

[0001]
[Industrial application fields]
The present invention provides a coating comprising at least one surface of a mixture of a metal oxide and a metal fluoride, a metal oxyfluoride, or the metal oxyfluoride and the mixture (hereinafter collectively referred to as metal oxyfluoride). With regard to a metal material on which a film is formed, the object is to provide a metal material having high corrosion resistance and high insulation used for semiconductor materials and capacitor materials.
[0002]
[Prior art]
Examples of means for forming an oxide film on the metal surface include means for heating in an atmosphere containing oxygen or water vapor, chemical vapor deposition (CVD), and anodizing.
[0003]
Examples of means for forming a fluoride film on the metal surface include a means for heating in a fluorine-based gas atmosphere and a means for performing sputtering in a fluorine gas atmosphere described in JP-A-2-263972.
[0004]
Each of the oxide film and the fluoride film has its characteristics and is properly used according to its application. The oxide film is used on the gas contact surface of a gas supply line used for semiconductor manufacture, thereby reducing corrosion and contributing to improvement in the yield of semiconductor manufacture. It is also used as an insulating film for other capacitors.
On the other hand, the fluoride film is used on the surface of a member using a fluorine-based gas to reduce corrosion.
[0005]
Thus, in the case of forming a film having the characteristics of both the oxide film and the fluoride film, an oxyfluoride film can be considered. A simple method of forming an oxyfluoride film is a heat treatment in the presence of gas, but even if it coexists, fluorine has excellent reactivity with the metal, so the oxidized metal is immediately fluorinated, and finally Only a fluorinated film is formed.
[0006]
[Problems to be solved by the present invention]
The present invention has been made to solve the above-described problems of the prior art. Since no metal material with a mixed layer of fluoride and oxide formed on the surface has been obtained at present, it is necessary to form a metal oxyfluoride film on at least a part of the metal surface, which leads to high corrosion resistance. It is to form a metal oxyfluoride film having both high insulation properties.
[0007]
[Means for Solving the Problems]
The present invention uses a metal material in which the melting point of a metal fluoride produced by fluorination is 500 ° C. or less, a film made of a mixture of a metal oxide and a metal fluoride, a film made of a metal oxyfluoride, or film made from the mixture with a metal oxyfluoride material is a metal material formed on at least one surface thereof.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The metal material according to the present invention has, on at least one surface thereof, (a) a layer comprising a mixture of an oxide and a fluoride of the metal material,
(B) a layer made of the acid fluoride;
(C) a layer composed of both (a) and (b) above,
And at least one layer is formed.
In the present invention, these (a) to (c) are sometimes collectively referred to simply as a metal oxyfluoride layer.
[0009]
These oxyfluoride layers have extremely excellent corrosion resistance and insulation resistance (because metal oxide and metal fluoride coexist), and are extremely suitable as materials for semiconductors and capacitors. .
[0010]
First, in the present invention, the oxyfluoride layer may be formed not only on the entire surface of the metal material but also on a part thereof. That is, not only when it is formed on the entire surface, the surface of the metal material itself may remain as it is. In short, this oxyfluoride layer may be formed at the site to be used. The oxyfluoride layer may be formed concentrated on one place of the metal material, or may be formed by being scattered as appropriate.
[0011]
For example, in the case where the metal material is a plate-like material, it is most often formed on the entire surface, but it is not limited to this, and the back surface and the front surface, only the back surface or these surfaces or It may be formed on a part of the back surface.
[0012]
The metal oxyfluoride coating of the present invention will be described in some detail below.
[0013]
In the case of the mixture of the oxide (a) and fluoride, the ratio of oxygen atoms and fluorine atoms in the film is 1: 0.3 to 1: 0.7.
[0014]
The (b) oxyfluoride is obtained by oxyfluoriding a metal, which can be regarded as a single compound (not a mixture), and its typical structural formula is NbO. ₂ Represented by F.
[0015]
Said (c) is a case where said (a) and (b) coexist.
[0016]
The thickness of the oxyfluoride film formed in the present invention is about 0.01 to 100 μm, preferably about 0.2 to 100 μm. In this case, if the thickness does not reach 0.01 μm, the corrosion resistance and the insulation are insufficient, and conversely, if it exceeds 100 μm, the film may be brittle.
[0018]
Among these, those having a melting point of the metal material fluoride of 500 ° C. or less are preferable, 200 ° C. or less is more preferable, and 150 ° C. or less is particularly preferable. For this reason, niobium, tantalum, molybdenum, bismuth and the like are preferably exemplified.
[0019]
In the present invention, these various metals are used, and these alloys can also be used, and alloys having the melting point range are particularly preferable.
[0020]
In the present invention, this oxyfluoride layer has extremely excellent corrosion resistance and insulation resistance, and is therefore used very effectively in fields where these characteristics are required. For example, fields related to semiconductors and capacitors can be exemplified.
[0021]
[Action]
The means for forming the oxyfluoride layer of the present invention on the surface of the metal material is not limited in any way. For example, a typical method is as follows.
In the present invention, the oxyfluoride film is produced by reacting at least one surface of a metal material with an oxidizing gas and a fluorinated gas. The reaction is performed under a flow of oxidizing gas and fluorinated gas. It may be performed in an atmosphere enclosed in a chamber. When considering the cost of raw materials and environmental impact, it is preferable to perform the reaction in an atmosphere in which an oxidizing gas and a fluorinated gas are sealed in a chamber, but a higher purity metal oxyfluoride film is produced. When it is desired to carry out the reaction, it is particularly preferable to carry out the reaction under a stream of oxidizing gas and fluorinated gas.
[0022]
The purity of the oxidizing gas used in the present invention is not particularly limited, and is preferably 99% or more, more preferably 99.9% or more, and 99.99% or more. It is more preferable that it is 99.999% or more. If the impurity content exceeds 1%, it tends to be difficult to control the metal oxidation or fluorination treatment, which may cause spots on the metal surface. For example, it is difficult to say that the present invention is suitable for applications such as semiconductor materials and capacitor materials that require high reliability.
[0023]
Among impurities, since water tends to cause the above-mentioned problems, its concentration is preferably 1000 ppm or less, more preferably 100 ppm or less, further preferably 50 ppm or less, and 10 ppm or less. It is particularly preferred.
[0024]
The purity of the fluorinated gas used in the present invention is not particularly limited and is preferably 99% or more, more preferably 99.9% or more, and 99.99%. More preferably, it is more preferably 99.999% or more. If the impurity content exceeds 1%, it is difficult to control the metal oxidation or fluorination treatment, and the metal surface may be spotted. For example, high reliability such as semiconductor materials and capacitor materials is required. It becomes difficult to say that it is suitable for application to the intended use.
[0025]
Among impurities, since hydrogen fluoride is likely to cause the above-mentioned problems, the concentration thereof is preferably 1000 ppm or less, more preferably 100 ppm or less, further preferably 50 ppm or less, and more preferably 10 ppm or less. It is particularly preferred that
[0026]
In the present invention, the oxidizing gas and the fluorinated gas can be diluted with an inert gas. Specific examples include gases such as nitrogen, helium, neon, argon, krypton, and xenon. The purity of the inert gas may be based on the purity of the oxidizing gas and the fluorinated gas, and is not particularly limited, but is preferably 99% or more, more preferably 99.9% or more. 99.99% or more, more preferably 99.999% or more. If the impurity content exceeds 1%, it may be difficult to control the metal and control the fluoride film, and the surface may be spotted. For example, the purity of the obtained mixed film of oxide and fluoride is low. Therefore, it is difficult to apply to applications that require high reliability.
[0027]
Among impurities, water is likely to cause the above-mentioned problems. Therefore, its concentration is preferably 1000 ppm or less, more preferably 100 ppm or less, further preferably 10 ppm or less, and 1 ppm or less. It is particularly preferred.
[0028]
In the present invention, it is necessary to oxidize and fluorinate the metal substrate in an atmosphere having a temperature equal to or higher than the melting point of the metal fluoride produced by the reaction between the metal material and the fluoride gas. When the treatment is performed at a temperature lower than the melting point, the oxidation reaction is inhibited, so that only metal fluoride is formed on the metal surface.
[0029]
In the present invention, all kinds of metal materials can be used as described above. Particularly, when the melting point of the fluoride of the metal material is low, for example, arsenic (arsenic pentafluoride; melting point = −80 ° C.) And antimony (antimony pentafluoride; melting point = 8 ° C.), molybdenum (molybdenum hexafluoride; melting point = 17.5 ° C.), tungsten (tungsten hexafluoride; melting point = 2.3 ° C.), etc. At this time, it is preferable to take care that the reaction temperature does not exceed the melting point of the corresponding fluoride.
[0030]
In the present invention, the reaction temperature is equal to or higher than the melting point of the fluoride, but is preferably 20 to 350 ° C. higher than the melting point. Particularly preferred is a temperature 20 to 150 ° C. higher. The reaction time is usually 0.5 to 5 hours, preferably 0.5 to 3 hours.
[0031]
The thickness of the metal oxyfluoride film of the present invention thus obtained is generally in the range of 0.01 to 100 μm. When it is necessary to adjust the thickness of the film, a film having a desired thickness can be obtained by controlling the reaction temperature, the concentration of the fluorinated gas and the oxidizing gas, and the reaction time.
[0032]
Is the reaction vessel used in the present invention coated with a material that does not discharge impurities in the presence of fluorine gas, such as a fluororesin film such as PFA or PTFE, or a metal fluoride film that has been subjected to a fluorination passivation treatment? In addition, it is desirable that the entire structure is manufactured from the viewpoint of preventing impurities from being mixed into the obtained film and preventing the occurrence of surface spots.
[0033]
【Example】
The present invention is specifically illustrated below. The present invention is not limited to these.
[0034]
The evaluations in Examples and Comparative Examples were performed by the following methods (A) to (C).
[0035]
(A) Film composition: Metal, fluorine and oxygen contents were evaluated by X-ray photoelectron spectroscopy.
[0036]
(B) Film thickness: The thickness of the film was evaluated by X-ray photoelectron spectroscopy (in terms of thermal oxide film of silicon).
[0037]
(C) Corrosion resistance; after immersion in a 5% aqueous hydrochloric acid solution at room temperature for 24 hours, the presence or absence of changes in the surface state was evaluated by a microscope and visual observation. When the surface did not change, it was judged that the corrosion resistance was good, and when the change was observed, the corrosion resistance was insufficient.
[0038]
[Example 1]
A niobium plate (5 cm × 1 cm) having a thickness of 1 mm was placed in a chamber having an inner surface of 100 μm coated with PTFE, and the chamber was sufficiently depressurized, and then purged with nitrogen having a purity of 99.99% or more. Once the inside of the chamber is sufficiently reduced in pressure once more, a mixed gas of 9% purity fluorine 1%, purity 99.99% purity oxygen 10%, purity 99.99% purity nitrogen 89% is put into the chamber. When the mixture returned to normal pressure, the supply of the mixed gas was stopped and left at 200 ° C. for 1 hour. Thereafter, the temperature was returned to room temperature while purging with nitrogen to obtain a niobium oxyfluoride film having a thickness of 10 μm. The composition of the obtained film was Nb = 32%, F = 16%, O = 52%, and the corrosion resistance was good.
[0039]
[Examples 2 to 5]
Respectively, the same as Example 1 except that the fluorine concentration was changed from 1% to 5% [Example 2], and the same as Example 1 except that tantalum was used instead of niobium [Example 3]. [Example 4], except that the mixed gas was flowed while maintaining the normal pressure [Example 4], except that argon having a purity of 99.99% or more was used instead of nitrogen having a purity of 99.99% or more. Were treated in the same manner as in Example 1 [Example 5] to produce metal oxyfluoride films. As a result, in Example 2, a metal oxyfluoride film having a film thickness of 15 μm and a composition of Nb = 32%, F = 16%, O = 52%, and in Example 3, a film thickness of 1 μm and a composition of Ta = 32%. , F = 16%, O = 52% metal oxyfluoride film, in Example 4, the film thickness is 10 μm and the composition is Nb = 32%, F = 16%, O = 52% However, in Example 5, metal oxyfluoride films having a film thickness of 10 μm and compositions of Nb = 32%, F = 16%, and O = 52% were obtained. Moreover, all the metal oxyfluoride films obtained in Examples 2 to 5 had good corrosion resistance.
[0040]
[Comparative Example 1]
When stainless steel (SUS316L) was treated in the same manner as in Example 1, a film having a thickness of 0.1 μm was obtained. However, when this film was evaluated, oxygen was not detected, and it was found that the film was a metal fluoride.
[0041]
[Comparative Example 2]
Stainless steel (SUS316L) that was not oxidized and fluorinated was insufficient in corrosion resistance.
[0042]
[Example 6]
A metal oxyfluoride film was produced in the same manner as in Example 1 except that nitrogen having a purity of 99% and a water content of 5000 ppm was used instead of nitrogen having a purity of 99.99% or more. The obtained metal oxyfluoride film had a film thickness of 10 μm and a composition of Nb = 32%, F = 16%, O = 52%, and some color spots were generated on the surface. However, the corrosion resistance was good.
[0043]
[Example 7]
A metal oxyfluoride film was produced in the same manner as in Example 1 except that the temperature was changed to 400 ° C. instead of 200 ° C. After the reaction, it was confirmed that PTFE and the like covering the chamber used for the reaction were deformed due to high temperature. The obtained metal oxyfluoride film had a film thickness of 100 μm and a composition of Nb = 32%, F = 16%, and O = 52%. However, the corrosion resistance was good.
[0044]
From the above result, it was confirmed that Examples 1-7 according to the present invention have a metal oxyfluoride film formed on the metal surface. Moreover, it was confirmed that Examples 1-5 which satisfy | fill the suitable conditions of this invention among these can manufacture a metal oxyfluoride film | membrane especially favorably.
[0045]
[Effect of the present invention]
In the present invention, a metal oxyfluoride film, more specifically, a mixed film of oxide and fluoride layers, a film made of oxyfluoride, or a mixed film of these is formed on the surface of a metal material for the first time. Corrosion resistance and insulation resistance are extremely excellent, and the industrial effect is extremely large.

Claims (10)

Using a metal material whose melting point of metal fluoride generated by fluorination is 500 ° C. or less, a film made of a mixture of metal oxide and metal fluoride, a film made of metal oxyfluoride, or metal oxyfluoride A metal material in which a film composed of a mixture and the mixture is formed on at least one surface thereof. The metal material according to claim 1, wherein the melting point is 200 ° C. or less. The metal material according to claim 1 or 2, wherein the metal material is niobium, tantalum, molybdenum, or bismuth. The metal material according to any one of claims 1 to 3, wherein the film is a film formed by heating in a gas atmosphere. The metal material according to any one of claims 1 to 4, wherein the ratio of oxygen atoms and fluorine atoms to the total number of atoms in the film is 20 to 60% and 10 to 30%, respectively. The metal material according to any one of claims 1 to 5, wherein a ratio of oxygen atoms and fluorine atoms in the film is 1: 0.3 to 1: 0.7. The metal material according to claim 1, wherein the formed film has a thickness of 0.01 to 100 μm. The metal material according to any one of claims 1 to 7, wherein the metal material is formed by heating the metal material at a temperature equal to or higher than a melting point of the metal fluoride in a coexisting gas atmosphere of fluorine and an oxidizing gas. The metal material according to claim 8, wherein the temperature is 20 to 350 ° C. higher than the melting point . The metal material according to claim 8 or 9, wherein the purity of the oxidizing gas and the fluorine gas is 99.99% or more.