JPH07207459A - Metal material coated with multilayered film - Google Patents

Abstract

PURPOSE:To obtain a multilayer coated metal material excellent in corrosion resistance even in an environment exposed to corrosive gas such as in a chamber for production of semiconductors by utilizing a Ti alloy amorphous layer. CONSTITUTION:The metal material has a protective film which protects the metal base 1 from corrosive gas 8. The film consists of one or more Ti-X layers 6 containing Ti and X and one or more Ti-Y-N layers 7 containing Ti and N. X is same or different for layers and selected from Al, Si, Cr, Fe, Co, Ni, Nb, Mo, W, Re, Hf, Ta which includes inevitable impurities. Y may be an inevitable impurity, or may be intensively added as an additive, and is selected from the same groups as for X. By this method, the Ti-X layers in the multilayered film for metal material are formed in an amorphous or granular state but not in a columnar structure. Thus, continuity of film defects can be cut off, and the corrosion resistance of the film is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-layer coating metal material used in an environment exposed to corrosive gas or corrosive liquid such as a semiconductor manufacturing chamber.

[0002]

2. Description of the Related Art In a semiconductor manufacturing process, a semiconductor manufacturing chamber or the like is exposed to a corrosive gas or liquid because oxidation or ion implantation is performed in a hot and humid atmosphere. . Therefore, it is necessary to take measures to improve the anticorrosion property in order to protect the metal material used for the semiconductor manufacturing chamber and the like from such a severe environment.

As a conventional technique with improved anticorrosion properties,
A material in which TiN is directly coated on the surface of the metal material (base material) (Yamaguchi et al., Journal of Japan Institute of Metals, 56, 3, (1992), 294), and between the metal material (base material) and the TiN film, an intermediate Metallic Ti or TiC coating as a layer ([2] Y. Massiani et
al., Thin Solid Film, 217, (1992), 31).

However, in the above, there is a problem that unless the thickness of the TiN film is set to 6 μm or more, the TiN film cannot be sufficiently shielded from the external environment and cannot function as a corrosion resistant film. In addition, the adhesion between the TiN coating and the base material is poor, and in a corrosive environment, defects such as pinholes in the coating make it easy for the corrosive solvent to enter and corrode the base material, or even peel the coating. was there. Furthermore, a TiN film having a thickness of 6 μm or more is too thick and is more likely to be peeled off. Moreover, it is economically disadvantageous that the film thickness is too thick. As described above, the above-mentioned metallic materials have various problems in practical use when they are used as materials having good corrosion resistance.

On the other hand, the above-mentioned
i or TiC), which allows the base metal and T
The adhesion with the iN film is improved. However, even in the case of the above, the pinholes (defects) generated in the film are not completely eliminated, and since the area of this pinhole is large, the corrosive solvent penetrates from the pinhole and the TiN layer peels off. , And further Ti (or TiC)
There is a problem that the corrosive solvent penetrates through the pinholes in the layer to corrode the base material, and in the case of, the corrosion resistance could be improved by only about half of that.

[0006]

Therefore, the inventors of the present invention have previously proposed Japanese Patent Application No. 5-288484 as an invention that solves these problems.
No. has been filed. The multilayer coating metal material according to the invention of the application has a structure in which a laminated group of a Ti layer and a TiN layer is set as one unit, and two or more units are vapor-phase coated on the surface of a metal base material to be laminated. Among them, the first layer is a Ti layer, the outermost layer is a TiN layer as viewed from the base material side, and the thickness of the entire coating is set to 5 μm or less. In this prior invention, since the coating is multi-layered, defects such as penetrating the surface of the coating to the surface of the base material are considerably reduced, and a large number of thin films are laminated, so that the thickness of the entire coating is reduced (5
Even if it is less than or equal to μm), the effect of corrosion resistance can be sufficiently exhibited, and the ease of peeling of the coating film due to the thick film pressure can be reduced.

As described above, according to the invention of the above-mentioned prior application, the substantial defect area ratio generated in the coating was greatly reduced, and the corrosion resistance could be considerably improved. However, in the application to the actual member, the defect area ratio is improved. It was considered desirable to further reduce Then, when the invention according to the above-mentioned prior application was further examined, the following problems were found.

That is, the vapor-phase coating film, particularly the TiN film, has a strong tendency to grow in a very thin columnar structure depending on the film forming conditions.
The Ti layer is also formed into a columnar shape by affecting the growth shape of the Ti layer thereon. When a Ti / TiN multilayer film was actually formed,
It was observed that the structure of the Ti layer was influenced by the stable columnar structure of the TiN layer and had a columnar shape with the same cross section. Therefore, there is a problem that defects generated in the vapor-phase coating film propagate through the gaps between the columns of the columnar structure and penetrate from the substrate interface to the outermost surface of the film.

FIG. 3 is a cross-sectional view schematically showing the film portion in order to explain this problem. In the figure, 1 is a metal base material,
2 is a Ti layer, 3 is a TiN layer, and 8 is a corrosive gas to which this metal material is exposed. As shown in the figure, since the Ti layer 2 and the TiN layer 3 have a columnar structure having the same width, the gap between the adjacent columnar structures penetrates in the up-down direction, so that a plurality of layers are formed as a whole. However, the result is the same as if the pinhole penetrated vertically.
In the actual structure, not all the pinholes penetrate, but there are some columnar structures that are slightly displaced.
It has been found that there are many risks of the above problems occurring in an actual use environment.

The present invention has been made to solve the above problems, and causes corrosion even in an environment exposed to a corrosive gas or liquid such as a semiconductor manufacturing chamber. It is an object of the present invention to provide a further improved multi-layer coating metal material which is free from the above.

[0011]

The multi-layer coating metal material according to the present invention has a layer in which the coating contains one or more layers of Ti and X (which may further contain inevitable impurities; hereinafter referred to as Ti-X layer). And at least one Ti and N layer (which may further contain an element Y which is the same as or different from the element X and other unavoidable impurities; hereinafter referred to as a Ti-Y-N layer),
When viewed from the base metal side of the coating, the first layer is the Ti-X layer,
The outermost layer is the Ti-Y-N layer, and the X in each layer is the same or different and is Al, Si, Cr, F.
The gist is that it is at least one selected from the group consisting of e, Co, Ni, Nb, Mo, W, Re, Hf, and Ta.

[0012]

[Function] As described above, the corrosion of the coated metal material in a corrosive environment causes the corrosive solution or gas to invade the base material from the defective portion such as the pinhole existing in the coating to corrode the base metal, and the corrosion causes the coating to be damaged. It is considered that this is because the area of the defective portion is peeled off and the progress of corrosion is further accelerated. Therefore, in order to suppress corrosion, it is considered important to reduce defects propagating through the coating and improve the adhesion of the coating.
1 and 2 are schematic diagrams showing the vicinity of a coating of a metal material coated with a multilayer coating according to the present invention, and the present invention will be described below using this drawing as an example.

In the figure, 1 is a metal base material and 8 is a corrosive gas. Reference numerals 4 and 6 are Ti-X layers, and these X are the same or different and are Al, Si, Cr, Fe, Co, N.
It is one or more selected from the group consisting of i, Nb, Mo, W, Re, Hf, and Ta. Needless to say, the Ti-X layer may contain inevitable impurities.

Reference numerals 5 and 7 are Ti-Y-N layers. This Y mainly refers to the additional element X when the additional element X of the Ti-X layer inevitably enters the Ti-N layer during film formation. Although Y may inevitably enter in this way, it may be positively added as an additional element, and the additive element may be Al, Si, Cr, F as in the case of X above.
e, Co, Ni, Nb, Mo, W, Re, Hf, Ta
(Hereinafter, these are collectively referred to as additional elements).
The Ti-Y-N layer may be a Ti-N layer without the additive element X of the Ti-X layer. Ti-Y-N
It goes without saying that the layer may further contain other unavoidable impurities.

As shown in the figure, the Ti-X layer in the present invention is in a non-crystalline state (FIG. 1) or isotropically grown grains (FIG. 2), and these are columnar. By blocking the upper and lower communication of the structure, the outside air and the surface of the base material are blocked and the anticorrosion effect is exerted.

Of the above additive elements corresponding to X, Al, N
In the case of i, Fe and Si (hereinafter, these are collectively referred to as the first group additive element), an amorphous film is formed when alloyed with Ti. Since such an amorphous vapor-phase coating film has no crystal grain boundary, the continuity with the columnar structure can be cut off.

FIG. 1 shows the structural model,
As shown in the figure, since the Ti-X layer 4 is made amorphous, even if the Ti-Y-N layer 5 has a columnar structure, such a Ti-X layer 4 is inserted. Therefore, the film defect due to the columnar structure does not penetrate to the surface of the base material 1. Furthermore, even if there are defects in both the Ti-X layer 4 and the Ti-Y-N layer 5, there is almost no chance that these defects will be formed at the same position, and the positions will be displaced between the layers. Since it is considered that it exists, even if the corrosive solution or the like enters from the pinhole of the uppermost layer, it does not reach the base material straightly and is not corroded.

On the other hand, of the additive elements corresponding to X, other than the above, that is, Cr, Co, Nb, Mo, W, Re, Hf, T
In the case of a (hereinafter collectively referred to as the second group additive element), when forming an alloy film with Ti, a structure other than the columnar structure is preferentially grown. FIG. 2 shows the structural model. In the case of Ti-X which is a second group additive element, the above first
Although it does not become amorphous like Ti-X of the group addition element, the Ti-X layer 6 does not have a columnar structure as shown in FIG. Even if the columnar structure is adopted, the Ti-X layer 6 prevents the defective portion due to the columnar structure from communicating with the surface of the base material 1.

Nitrogen (N) introduced into the Ti-Y-N layers 5 and 7 in the present invention increases the hardness of the layers, which increases the strength of the entire coating. Further, the introduction of nitrogen improves the corrosion resistance of the Ti-Y-N layer. Therefore, by using the Ti-Y-N layer as the outermost layer, excellent corrosion resistance is exhibited as a whole.

The elements used as X and Y may be appropriately selected from the group of additive elements, and one or two or more elements may be selected to form a multi-element alloy. The concentration of X in the Ti-X layer is 10 to 60.
at% is recommended, and Y in the Ti-Y-N layer is recommended.
Is recommended to be 5 to 50 at%.

Since the Ti-X layer is formed as the first layer of the coating that is in direct contact with the metal base material, the Ti-X has good adhesion to the metal base material, and therefore the coating is peeled off. Can be suppressed. Ti-X and Ti-Y-N are both Ti
Is used as the base material, and therefore the metal coating material of the present invention has good adhesion from the base material to the outermost surface layer of the coating.

In the above description, the Ti-X layer and the Ti-Y-
The case of laminating two N layers each (four layers in total) is shown.
The effect of blocking defects by forming the -X layer is essentially sufficient. Therefore, in the present invention, the number of layers may be reduced to one. On the contrary, it is not excluded that the number of layers is three or more, and a large number of layers may be formed.

When two or more Ti-X layers and Ti-Y-N layers are formed, X and Y of each layer are not limited to the same kind in each layer, and different elements in each layer may be used. You may use. Further, X and Y may be the same kind of element or different kinds of elements may be used. Needless to say, as described above, the additional element as Y may not be added.

1 and 2, the Ti-X layer and the Ti-Y-
Although the structure in which the N layers are alternately laminated is shown, by adopting different elements as described above, for example, as the Ti-X layer, the first Ti-X layer (for example, Ti-Ta layer) and the second Ti-X layer are formed. A Ti-X layer (for example, a Ti-Ni layer) may be formed adjacent to each other. The same applies to the Ti-Y-N layer.

The material of the above-mentioned metal base material is not particularly limited. For example, when a material which does not passivate in an acidic aqueous solution and has poor corrosion resistance, such as an iron-based material or an aluminum alloy, is used as the base material. Especially effective for.

[0026]

EXAMPLES Examples and comparative examples of the present invention will be shown below. Using a mirror-finished plain steel as the metal base material, Ti-
The X layers and the Ti-Y-N layers were alternately vapor-grown and laminated to form a film. The total number of layers was 8, and the total thickness of the film was about 3 μm. In Table 1 below, additional elements corresponding to the above X and Y, and their content concentrations (a
t%).

With respect to these Examples 1 to 6 and Reference Example, the mechanically broken cross sections were structurally analyzed using a scanning electron microscope. Further, as an evaluation of the anticorrosion property, the defect area ratio was calculated from the anodic polarization curve in 1% sulfuric acid. The results are also shown in Table 1.

[0028]

[Table 1]

As a result of observation with an electron microscope, Examples 1 to 1
6 and the reference example had a total film thickness of about 3 μm and were covered with 8 layers. Further, the Ti-Y-N layer had a columnar structure, but the Ti-X layers of Examples 1 and 2 in which the second group additive element was selected were granular,
The Ti-X layers of Examples 3 to 6 in which the first group additive element was selected were amorphous. That is, the Ti-X layer had a granular or amorphous structure without being affected by the columnar Ti-Y-N layer.

As shown in Table 1, in Examples 3 to 6 in which the first group additive element was selected, the film defect area ratio was extremely low. The defect area ratio is reduced to about 1/10 of that of the reference example in which no additional element is added, and the corrosion resistance is remarkably improved.

Example 1, in which the second group additive element was selected,
The defect area ratio of No. 2 is reduced to 1/2 to 1/3 as compared with the reference example. Also in Examples 1 and 2, the corrosion resistance is improved as compared with the reference example adopting the above-mentioned prior application method. It is considered that such improvement in corrosion resistance is due to the fact that the Ti-X layer is amorphous or granular, and therefore continuous growth of film defects is prevented.

[0032]

The multi-layer coating metal material according to the present invention is
Since it is configured as described above, Ti-
Since the X layer becomes amorphous or granular and does not have a columnar structure, the communication of film defects is blocked and the corrosion resistance is improved. Therefore, it is possible to provide a metal material having excellent corrosion resistance even in an environment exposed to a corrosive gas or the like such as a semiconductor manufacturing chamber.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a structural model in the vicinity of a film of a multilayer film-coated metal material according to the present invention.

FIG. 2 is a diagram showing another example of a structural model in the vicinity of a film of a multilayer film-coated metal material according to the present invention.

FIG. 3 is a diagram showing a structural model in the vicinity of a film of a conventional multilayer film-coated metal material.

[Explanation of symbols]

 1 Metal Base Material 4,6 Ti-X Layer 5,7 Ti-Y-N Layer 8 Corrosive Gas

Claims (1)

[Claims] 1. A metal material having a coating on the surface of a metal base material, wherein the coating is composed of one or more layers containing Ti and X and one or more layers containing Ti and N. A multilayer coating metal material, wherein the first layer is a layer containing Ti and X, and the outermost layer is a layer containing Ti and N, as viewed from the base material side. [X in each layer
Are the same or different from Al, Si, Cr, Fe,
At least one selected from the group consisting of Co, Ni, Nb, Mo, W, Re, Hf, and Ta]