JP3230260B2 - Surface coated metal material for vacuum equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is excellent in corrosion resistance and degassing properties in high vacuum conditions and corrosive gas environments, such as a vacuum chamber for semiconductor manufacturing equipment and its surrounding vacuum members or CVD equipment. The present invention relates to a surface-coated metal material.

[0002]

2. Description of the Related Art For example, in the production of semiconductors, S
BF ₃ , BCl ₃ , SiF ₄ ,
Corrosive gases such as SiH ₂ , FOCl ₃ , WF ₆ , and MoF _6, and extremely reactive gases such as F ₂ , Cl ₂ , and HCl are used. Further, when processing with these gases, it is necessary to completely remove the residual gas by setting the inside of the chamber to an ultra-high vacuum of about 10 ^-10 to 10 ^-12 torr in order to prevent contamination of the Si wafer. . Therefore, a vacuum chamber for semiconductor manufacturing equipment and its related equipment materials must have good corrosion resistance to various corrosive gases, have low gas adsorption, and be easily degassed even if adsorbed. Rather, these requirements are becoming more stringent as semiconductor manufacturing technology becomes more sophisticated.

[0003] By the way, the inner wall material for a vacuum chamber which is currently in practical use is a stainless steel material which is mirror-finished by electrolytic polishing or the like and is coated with a corrosion-resistant oxide film in order to suppress gas adsorption and enhance degassing. are known, the surface roughness of the surface-coated stainless steel is of the order of R _max of about 0.3 [mu] m, to obtain a tentative satisfaction for gas adsorbing and degassing properties. However, the coated stainless steel material has insufficient corrosion resistance, and often suffers from the problem of being corroded and deteriorated by the corrosive gas as described above. Moreover, when the surface is corroded by corrosive or reactive gases, those gases enter the inside of the substrate,
There is also a problem that subsequent degassing becomes extremely difficult.

[0004] Further, as a base material to replace stainless steel,
Al, Al which is lighter and higher in specific strength than the stainless steel material
Attempts have been made to use alloys, Ti, Ti alloys, etc., but these are more susceptible to corrosion than the above-mentioned coated stainless steel materials, and are suitable as materials for vacuum equipment exposed to the corrosive gas atmosphere as described above. Lacks.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and its object is to provide excellent corrosion resistance to corrosive gases and reactive gases as described above. An object of the present invention is to provide a surface-coated metal material for a vacuum apparatus which has a low gas adsorption (hereinafter, this property is referred to as gas adsorption resistance) and has excellent degassing properties.

[0006] The structure of the surface-coated metal material according to the present invention that can solve the above-mentioned problems is that the surface of the metal substrate for a vacuum device has an oxide (excluding Fe and Cr oxides; the same applies hereinafter), The coating is at least one surface layer selected from the group consisting of nitrides, carbides, borides and fluorides, and the surface roughness of the outermost layer of the coating is R
It has a gist where max ≦ 1.0 μm.

[0007]

As described above, according to the present invention, at least one compound selected from the group consisting of oxides, nitrides, carbides, borides, and fluorides is formed on the surface of a metal substrate for a vacuum device. A coating layer in which the surface roughness of the surface layer portion is _Rmax ≦ 1.0 μm is formed. The surface layer having the specified surface roughness of the outermost layer portion ensures excellent corrosion resistance while maintaining the surface roughness. Has significantly improved the gas adsorption resistance and degassing property.

That is, in the present invention, as a means for securing the above-mentioned corrosion resistance as a metal material for a vacuum device, the metal material is selected from the group consisting of oxides, nitrides, carbides, borides, and fluorides. It is covered with a corrosion-resistant protective film made of at least one selected compound. Although the corrosion resistance is improved by the protective film, the gas absorption resistance and the degassing property are not simultaneously improved by the protective film.

Therefore, as a result of further study to clarify the characteristics of the protective film that can sufficiently satisfy the requirements for the gas adsorption resistance and the degassing property as well as the corrosion resistance, as a result, the surface roughness of the protective film was reduced. R _max : 1.0 μm or less, more preferably 0.1 μm or less.
It has been found that, when the thickness is set to 3 μm or less, more preferably 0.1 μm or less, the amount of adsorbed gas is remarkably suppressed and the degassing property is also remarkably increased, so that the object of the present invention can be splendidly achieved.

The reason can be considered as follows.
That is, when the surface roughness of the coating is reduced, the surface becomes dense, the effective area for adsorbing corrosive gas is reduced, the absolute amount of gas adsorption is reduced, and the adsorbed gas is easily removed by degassing. Can be. In addition, when the coating surface becomes denser, the effective area in contact with the corrosive gas is also reduced, and the adverse effect of the corrosive gas on the coating is also suppressed in conjunction with the decrease in the amount of adsorbed gas, and as a result, the corrosion resistance was originally excellent. It is considered that the corrosion resistance deterioration of the coating is further suppressed, and excellent corrosion resistance is exhibited.

[0011] Such an effect is achieved by reducing the surface roughness to 1.0 μm.
When the surface roughness is made 0.3 μm or less, more preferably 0.1 μm or less, the effect becomes more remarkable.

In the present invention, examples of the compound constituting the surface coating include various oxides, nitrides, carbides, borides, and fluorides which are chemically stable and exhibit excellent corrosion resistance. Are Ti, Zr,
Oxides of one or more elements selected from the group consisting of Ta, Si, Al, Y, Cr and B, Ti, Zr, Ta,
A nitride of one or more elements selected from the group consisting of B, Si and Al; a carbide of one or more elements selected from the group consisting of Ti, V, Ta, B and Si; and Ti, Zr and Ta Boride of one or more elements selected from the group, Ti, Zr, Ni, Fe, Ta, Re, Cu, A
It is a fluoride of one or more elements selected from the group consisting of 1, Mn and Al.

All of the compounds shown in (1) to (4) have excellent corrosion resistance, and can be used as a single substance. In addition, depending on the type of corrosive gas, two or more compounds can be combined to further increase the corrosion resistance. Of course it is possible. The surface layer may of course have a single-layer structure, but if necessary, it is also effective to further increase the corrosion resistance to a plurality of corrosive gases by forming a multilayer structure of two or more layers.

The surface roughness of the above surface coating is R _max ≦ 1 μm
As a specific means for achieving the above, for example, a method of controlling the film forming conditions and the like according to the film forming material to ensure the surface roughness R _max ≦ 1 μm in a state where the film is formed,
Alternatively, a method of polishing the film with an ultrafine abrasive such as a diamond paste after forming the film so that the surface roughness is _Rmax ≦ 1 μm, or the like can be adopted. Also if the coating constituent material is electrically conductive, a very effective composite electrolytic polishing method, thereby R _max ≦ 0.3 μm or less, further R _max
Very small surface roughnesses of ≦ 0.1 μm or less can be easily achieved. The surface coating may be formed by any method, but the most common are thermal spraying, PVD
And a vapor phase plating method such as a CVD method.

In the present invention, the type of the metal substrate for the vacuum apparatus is not particularly limited, but the most common ones are stainless steel, Al, Al alloy, Ti and Ti alloy. It is desired that these metal base materials are mirror-finished by electrolytic polishing or the like in order to smooth the surface as much as possible to suppress gas adsorption and enhance degassing properties.

In the case where the above-mentioned surface coating is formed on the surface of the metal substrate, depending on the type, the coating may have insufficient adhesion due to a lack of affinity between the metal substrate and the constituent material or a difference in thermal expansion coefficient. Is also conceivable. Therefore, in such a case, it is preferable to form the base layer for improving the adhesion on the surface of the metal base material before forming the surface coating.

The kind of such an underlayer should be selected according to the kind of the metal base material or the surface coating constituent material, and cannot be uniformly determined. Has affinity for both coating components,
In addition, it shows a coefficient of thermal expansion intermediate between the two, and preferably has a higher corrosion resistance than at least the metal base material in consideration of the corrosion resistance of the underlayer. Specific examples thereof include Zr, Ta, Nb, and W. , Mo, and the like, or their alloys are exemplified as preferred.

Next, the present invention will be described in detail with reference to examples. However, the present invention is not limited to the following examples, and it is possible to carry out the present invention appropriately modified in accordance with the above and subsequent points. Both are included in the technical scope of the present invention.

[0019]

EXAMPLE An aluminum alloy plate (JIS) was used as a metal substrate for vacuum equipment.
A 5052), Ti plate [JIS class 3] and stainless steel plate (SU
S 304), which is mirror-finished by electrolytic polishing, then a surface coating is formed by a DC / RF magnetron sputtering method, and then polished using a diamond paste to form a surface coating having the structure shown in Table 1. Then, a surface-coated metal plate (test plate) was obtained. A gas corrosion test and a degassing test were performed on the obtained test plates by the following methods, and the results shown in Table 1 were obtained.

<Gas Corrosion Test> Each test plate was 100% Cl ₂
(168 kg / cm ² ) in a gas atmosphere at room temperature (25 ° C.) for 168 hours, and the corrosion rate is determined from the weight change before and after the corrosion test.
Then, from the relative corrosion amount when the gas corrosion rate of the SUS 304 untreated plate was set to 1, the corrosion resistance was evaluated according to the following criteria. ◎: less than 0.2 ○: 0.2 to 0.5 △: 0.5 to 0.8 ×: more than 0.8

<Degassing test> In order to make initial conditions uniform,
After baking each test plate at 450 ° C. for 1 hour in a vacuum, the plate is exposed to an atmosphere having a relative humidity of 70% for 10 minutes. It is then heated to 800 ° C. in a vacuum chamber and the type and amount of gas released is measured by a quadrupole mass spectrometer. Then, based on the relative gas release amount when the gas release amount of the SUS 304 untreated plate was set to 1, the degassing property was evaluated according to the following criteria. ◎: less than 0.01 ○: 0.01 to 0.02 △: 0.02 to 0.1 ×: more than 0.1

[0022]

[Table 1]

As is clear from Table 1, the non-treated materials (Nos. 23 to 28) are inferior in both degassing property and corrosion resistance. Those having a roughness (R _max ) exceeding 1 μm (No. 1)
9 to 22), both the degassing property and the corrosion resistance are insufficient. On the other hand, those having a surface coating satisfying the requirements of the present invention (Nos. 1 to 13) have the degassing property and the corrosion resistance. Good results were obtained in each case. Also N
o. 14 to 18 are examples in which a corrosion-resistant metal layer was provided as an intermediate layer between the base material and the coating, and in particular, gas corrosion was further enhanced.

Table 2 shows that a Ti substrate [JI
SH 4600 (1988)], using BN, ZrO _2, or TiN as a surface coating component, and examining the effect on degassing properties when the surface roughness of the surface coating is variously changed. is there. However, the evaluation criteria for degassing were as follows. ×: comparable to untreated SUS (surface roughness R _max = 1μm) △: 10 untreated SUS (surface roughness R _max = 1 [mu] m)
１: 50 or less of untreated SUS (surface roughness R _max = 1 μm)
1/10 or less: 10 of untreated SUS (surface roughness R _max = 1 μm)
Less than 1/0

[0025]

[Table 2]

As is evident from Table 2, the degassing properties vary significantly depending on the surface roughness of the surface coating, and R _{max is set} to 1.
By setting the thickness to 0 μm or less, a remarkably excellent degassing property of 1/50 or less of the untreated stainless steel sheet can be obtained.

[0027]

The present invention is constituted as described above. The metal substrate for vacuum equipment is selected from oxides, nitrides, carbides, borides and fluorides and has a surface By being protected by a surface coating layer having a roughness R _max of 1 μm or less, even when used in a device / equipment which is repeatedly exposed to a corrosive gas environment and a high vacuum environment, such as a semiconductor manufacturing device, it is excellent. In addition to exhibiting durability, the influence of the adsorbed gas can be suppressed as much as possible.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-247778 (JP, A) JP-A-63-199861 (JP, A) JP-A-2-57667 (JP, A) JP-A-2- 233133 (JP, A) JP-A-58-151469 (JP, A) JP-A-59-197566 (JP, A) JP-A-2-268824 (JP, A) JP-A-62-57640 (JP, A) JP-A-10-204526 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B01J 3/00 C23C 16/00-16/56 C23C 14/00-14/58 H01L 21 / 205 H01L 21/306 H01L 21/31

Claims (6)

(57) [Claims] The surface of a metal substrate for a vacuum device is made of an oxide.
(Excluding oxides of Fe and Cr) , nitride, carbide, boride and fluoride, and the surface roughness of the outermost layer of the coating is Rmax ≦ A surface-coated metal material for a vacuum device, which is 1.0 μm. 2. The method according to claim 1, wherein the oxide is Ti, Zr, Ta, S.
The surface-coated metal material according to claim 1, which is an oxide of at least one element selected from the group consisting of i, Al, Y, Cr, and B. 3. The method according to claim 1, wherein the nitride is Ti, Zr, Ta, B,
The surface-coated metal material according to claim 1, which is a nitride of at least one element selected from the group consisting of Si and Al. 4. The surface-coated metal material according to claim 1, wherein said carbide is a carbide of at least one element selected from the group consisting of Ti, V, Ta, Si and B. 5. The surface-coated metal material according to claim 1, wherein said boride is a boride of at least one element selected from the group consisting of Ti, Zr and Ta. 6. The method according to claim 1, wherein said fluoride is Ti, Zr, Ni, F.
2. A fluoride of at least one element selected from the group consisting of e, Ta, Re, Cu, Al and Mn.
The surface-coated metal material as described in the above.