JP2895554B2 - Vacuum container and component for vacuum equipment having multilayer coating - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a vacuum vessel and a component for vacuum equipment having a multilayer coating.

[Conventional technology]

Factors that determine the evacuation time when evacuating the inside of the vacuum vessel include the pumping speed of the pump, the conductance of the piping, the internal volume of the vacuum vessel, and the gas released from the inner wall of the vacuum vessel and the surface of the component. The released gas has a great influence on the ultimate pressure.

The sources of this released gas can be broadly classified as follows: gas adsorbed on the inner wall of the vacuum vessel and the surface of components in the vacuum, gas dissolved inside the material of the vacuum vessel and components, There are two types of gases that have been dissolved in and diffused to the inner surface of the vacuum.

Conventional vacuum vessels and components for vacuum equipment include those made of materials such as stainless steel or aluminum alloy.However, when these are used for vacuum, gas is released from the surface and the degree of vacuum does not rise easily, In order to reduce the released gas, the following measures have been taken.

(A) The surface in contact with the vacuum is mirror-finished by electrolytic polishing or the like to reduce the area where gas is adsorbed.

(B) The surface in contact with the vacuum is coated with a metal nitride that does not easily adsorb gas by reactive vapor deposition, and at the same time, the surface smoothness is increased.

(C) A boron nitride film is formed on the surface in contact with vacuum by heat treatment to reduce the amount of adsorbed gas.

As described above, all of the techniques (a), (b), and (c) reduce the amount of adsorbed gas by reducing the substantial surface area of the inner wall of the vacuum vessel and the surface of the component where gas can be adsorbed, Attempts have been made to reduce gas adsorption by forming a surface layer in contact with vacuum with a material that does not easily cause gas adsorption, that is, a dense oxide film (a), a nitride film (b), and a boron nitride film (c).

[Problems to be solved by the invention]

As described above, the prior art attempts to suppress the gas by focusing only on the gas adsorbed on the surface, and measures to suppress the gas that diffuses from the inside of the material or through the material. Was not taken at all. In particular, the prior art has no suppression effect on hydrogen that easily diffuses inside the solid, and the ultimate pressure is limited.

In view of the above problems, the present invention not only reduces the amount of gas adsorbed on the surface in contact with vacuum, but also diffuses gas from the inside, a vacuum vessel having a multilayer coating that can also suppress release. The purpose is to provide parts for vacuum equipment.

[Means for solving the problem]

The object is to provide a vacuum vessel and a vacuum equipment part having a coating on a surface in contact with a vacuum, wherein the coating is a metal or a compound having a smaller gas adsorption than a base material of the vacuum vessel and the vacuum equipment part. And a vacuum vessel and a vacuum appliance part having a multilayer coating, comprising: a single layer of a metal compound having a gas permeability coefficient significantly lower than that of the base material or an intermediate layer which is a multilayer thereof. You.

[Action]

When using a vacuum container having a multilayer coating and a component for vacuum equipment configured as described above, when exhausting gas from the vacuum container, diffusion and release of gas from inside the material can be suppressed, and gas from the surface can be suppressed. Since the discharge is small, the evacuation time until the target pressure is reached can be shortened, and the ultimate pressure can also be lowered.

〔Example〕

 Hereinafter, embodiments will be described with reference to the drawings.

A stainless steel (SUS304) having a thickness of 2.5 mm is prepared as a base material, and a titanium nitride film is formed on the surface thereof by a reactive vapor deposition method. First, as shown in FIG.
The SUS304 base material (6) is held so that it can be rotated as indicated by the arrow. This base material (6) is rotated, and the upper surface of titanium (3), which is an evaporation material disposed in the vacuum chamber (1), is irradiated with an electron beam (5) from a hollow cathode electron beam gun (2) to produce titanium. When a nitrogen gas (N ₂ ) as a reaction gas is introduced from a nitrogen gas introduction pipe (4) while evaporating the (Ti) vapor, a titanium nitride film (7) as an intermediate layer is formed on the surface of the base material (6). Been formed. It continued until the film thickness became 1.5-2 micrometers. Then, in a different vacuum chamber, a platinum film (8) having a thickness of 0.1 to 0.2 μm, which is the outermost surface layer, was formed on the titanium nitride film (7) by a vacuum evaporation method (see FIG. 2 (d)). ).

The following comparative experiment was performed to confirm the effect of the component formed with the multilayer coating according to the present embodiment.

First, a titanium nitride film (7) similar to the intermediate layer of this embodiment is formed on the surface of a base material (6) SUS304 having the same size as that of this embodiment.
Comparative sample (b) with only (thickness 1.5 to 2 μm) formed
And a platinum film (8) (thickness:
A comparative sample (c) in which only (1 to 0.2 μm) was formed was prepared. Comparative sample (a) was obtained only from the base material, and sample (d) was obtained according to this example. FIG. 2 schematically shows a cross section of each sample.

These four types of samples were heated in an ultra-high vacuum apparatus under the conditions shown in FIG. 3 until time t, and then maintained at 500 ° C., for each of the samples, the adsorbed gas and the base material released from the surface. The gas emitted from the inside was measured. FIG. 4A to FIG. 4D show time-dependent changes in the amount of each detected gas type for each of the samples (a) to (d). Here, m / e represents the ratio between the mass number (m) of the gas species and the charge number (e) when it becomes charged particles in the detector.

In this experiment, the adsorbed gas was mainly released from the surface at the time of temperature rise, and as the temperature rose and the sample was heated (the latter half of the constant temperature region), gas mainly from the inside of the base material was diffused and released. Come.

In the case of sample (a) in FIG. 4A, water (m / e = 1
8) and a large amount of carbon monoxide (m / e = 28) detached from the surface,
After that, it gradually decreases, but the amount is still large. As the temperature rises, a large amount of hydrogen (m / e = 2) is detected, which is released from inside the base material (6).

In the case of the sample (b) in FIG. 4B, the amount of released hydrogen is significantly lower than that of the sample (a), although the amounts and tendency of water and carbon monoxide are almost the same. That is, it can be assumed that the titanium nitride film (7) serves as a diffusion barrier for hydrogen diffusing from inside the base material (6).

In the case of the sample (c) in FIG. 4C, the amount of water and carbon monoxide released at the time of temperature rise is significantly reduced as compared with the sample (a).
On the other hand, the release of hydrogen after the heating has proceeded is almost the same as that of the sample (a), although the timing at which the release reaches a peak is slightly delayed. That is, water that is adsorbed on the surface due to the coating of the platinum film (8),
It is assumed that the total amount of carbon monoxide was reduced.

In the case of the present embodiment shown in FIG. 4D, the amount of water and carbon monoxide desorbed at the time of temperature increase and thereafter is significantly reduced as in the case of FIG. 4C, as compared with the case of the sample (a). In addition, the amount of hydrogen released after heating is significantly reduced, and the time when the release is started is slightly delayed.

From the above experimental results, it can be understood that since the gas such as water and carbon monoxide is hardly adsorbed on the surface of the platinum film which is the outermost surface layer of this embodiment, the total amount of the adsorbed gas can be suppressed. or,
It can be seen that the titanium nitride film, which is the intermediate layer, acts as a barrier for the diffusion of gas, especially hydrogen, in the base material and can significantly reduce the amount of gas released from inside the base material. Furthermore, in FIG. 4C and FIG. 4D, the release time of hydrogen from inside the base material is delayed,
It is considered that the outermost layer also contributes to the function as a barrier against gas diffusion from inside the base material. Therefore, by using a film in which the outermost surface layer and the intermediate layer are combined as in the present embodiment, the respective functions are more effectively exhibited, and the total amount of released gas can be reduced.

Although the embodiments of the present invention have been described above, the present invention is, of course, not limited thereto, and various modifications can be made based on the technical concept of the present invention.

For example, instead of platinum in this embodiment, gold as the outermost surface layer,
Similar effects were obtained when palladium, tungsten, molybdenum, aluminum, silicon or metal sulfide, or boron nitride was used.

Further, instead of the titanium nitride of this embodiment, titanium carbide, aluminum oxide, silicon nitride, titanium boride,
A similar effect was obtained when a single layer film of one or more of chromium nitride, a titanium nitride / titanium carbide laminated film, or the like was used.

Further, in the embodiment, the reactive evaporation and the vacuum evaporation are used as the film forming method, but instead, a chemical vapor deposition, a sputtering or a wet plating method may be used.

Further, a film containing about 20% or more of the metal or the compound may be formed as the outermost surface layer, and only the components may be deposited on the film surface by heat treatment.

〔The invention's effect〕

Since the vacuum vessel and the vacuum equipment component having the multilayer coating of the present invention have the above-described configurations, the total amount of gas released from the surface of the base material that comes into contact with the vacuum in the vacuum atmosphere is reduced, and thus the evacuation time is reduced. The pressure can be shortened and the ultimate pressure can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of an apparatus for forming a film on the surface of a base material in an embodiment of the present invention, and FIG. 2 is a cross-sectional view showing the samples obtained by the present embodiment and the configuration of each sample for comparison with the samples. FIG. 3 is a schematic diagram, FIG. 3 is a graph showing the temperature conditions of the comparative experiment, and FIGS. 4A to 4D show the results of gas analysis of each sample. In the figure, (6) ... base material (7) ... titanium nitride film (8) ... platinum film

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Sonoko Tsukahara 5-9-9 Tokodai, Tsukuba, Ibaraki Pref. Tsukuba Super Materials Laboratory, Japan Vacuum Engineering Co., Ltd. 5-9-9 Kodaidai Tsukuba Super Materials Research Laboratory, Japan Vacuum Engineering Co., Ltd. (58) Field surveyed (Int. Cl. ⁶ , DB name) C23C 24/00-30/00 B01J 3/00-3/08

Claims (2)

(57) [Claims] 1. A vacuum vessel and a component for vacuum equipment having a coating on a surface in contact with vacuum, wherein the coating is a metal or compound having a smaller gas adsorption than a base material of the vacuum vessel and component for vacuum equipment. A vacuum vessel and a vacuum appliance part having a multilayer coating, comprising: a layer; and a single layer of a metal compound having a gas permeability coefficient significantly lower than that of the base material or an intermediate layer which is a multilayer thereof. 2. The method according to claim 1, wherein the outermost layer is any one of platinum, gold, palladium, tungsten, molybdenum, aluminum, silicon, metal sulfide, and boron nitride, and the intermediate layer is titanium nitride, titanium carbide, aluminum oxide. A vacuum container and a component for vacuum equipment having a multilayer coating according to claim 1, wherein the component is a single-layer film containing at least one of silicon nitride, titanium boride, and chromium nitride, or a titanium nitride / titanium carbide laminated film. .