JP3978050B2 - Surface treatment layer for turbo molecular pump - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a surface treatment layer for a turbo molecular pump used in an exhaust line of a semiconductor manufacturing facility.
[0002]
[Prior art]
A schematic structure of this type of turbomolecular pump is shown in FIG. The turbo molecular pump is provided with an intake port 2 in the upper part of the casing 1 and an exhaust port 3 in the lower part of the casing 1, and the rotor blade 5 provided in the rotor 4 is rotated at high speed in the space between the stationary blades 6 provided in the casing 1. As a result, the exhaust action is exerted to make the intake port 2 side into a high vacuum. Reference numeral 7 denotes a driving motor.
[0003]
In this turbo molecular pump, an aluminum alloy is usually used as a blade material from the viewpoints of light weight, low cost, strength, and the like. However, since aluminum alloys corrode significantly in a corrosive gas environment such as chlorine gas discharged in the semiconductor manufacturing process, it is necessary to perform excellent corrosion resistance treatment on the surface. In addition, another requirement indispensable for the wing material is high thermal radiation (emissivity). The reason is that a large amount of heat generated by high-speed rotation of the rotor needs to be released by radiation under a high vacuum where heat dissipation due to normal convection cannot be expected.
[0004]
Conventionally, various types of surface treatment techniques for internal parts of turbomolecular pumps made of an aluminum alloy are known as shown below.
[0005]
(1) An oxide film is formed on the surface of a base material by anodization.
(2) An electroless Ni plating layer is formed on the substrate surface.
(3) An electroless Ni plating layer is formed on the substrate surface, and an epoxy layer is formed thereon.
(4) Forming an electroless Ni-dispersed plating layer in which fine particles such as ceramic are dispersed on the surface of a substrate.
(5) An electroless black Ni plating layer is formed on the substrate surface.
[0006]
[Problems to be solved by the invention]
However, among the above-described techniques (1) to (5), although (1) is inexpensive and has high emissivity, there are a number of voids, and therefore there is a drawback in that degassing is large and corrosion resistance is weak.
Although (2) has high corrosion resistance, it has a drawback of low emissivity.
Although (3) can increase emissivity and corrosion resistance by adding an epoxy layer, it has a disadvantage that it is weak in the plasma environment.
Although (4) has high emissivity and corrosion resistance, it has a drawback of cost.
Although (5) has a high emissivity, it has a drawback of poor corrosion resistance.
[0007]
As described above, the above-described conventional technique has advantages and disadvantages, and has not yet fully satisfied the optimum conditions as a material for internal parts for a turbo molecular pump.
[0008]
In view of the above circumstances, an object of the present invention is to provide a surface treatment layer for a turbo molecular pump that has high corrosion resistance and thermal radiation, high plasma resistance, and can be realized at low cost.
[0009]
[Means for Solving the Problems]
The surface treatment layer for a turbo molecular pump according to the invention of claim 1 is a surface treatment layer formed on a moving blade or a stationary blade that is an internal component of the turbo molecular pump, and is a treatment liquid containing a fluorine compound and ammonium silicofluoride. , by immersing the aluminum or made of an aluminum alloy substrate, by treatment in a temperature range of 70 to 100 ° C., Ri Na to form a film of the fluorine compound to the substrate surface, the emissivity epsilon 0.7 It is set to about 0.8 .
[0010]
The surface treatment layer formed on the internal part of the turbo molecular pump needs to have high corrosion resistance and high heat radiation. By forming this film, it is possible to obtain a surface treatment layer for a turbo molecular pump that has both improved corrosion resistance and emissivity. Incidentally, the emissivity ε can be set to about 0.7 to 0.8. Further, the above-mentioned film can be made very thin (about 3 μm), and the dimensional change of the parts can be reduced. Therefore, it is not necessary to design the dimensions of the substrate in consideration of the film thickness in advance. Further, since the above film is not porous, there is no fear of degassing even when it comes into contact with the reactive gas. Moreover, since the durability against oxygen plasma is high, and a film can be formed only by immersing in the above-mentioned treatment solution, it can be realized extremely easily and inexpensively.
[0011]
A surface treatment layer for a turbo molecular pump according to a reference example is a surface treatment layer formed on an internal part of a turbo molecular pump, and an electroless Ni plating layer and an electroless layer are formed on the surface of a substrate made of aluminum or an aluminum alloy. It is characterized by forming a two-layered film of black Ni plating layers.
[0012]
The surface treatment layer formed on the internal parts of the turbo molecular pump needs to have high corrosion resistance and high heat radiation, but the electroless Ni plating layer is formed on the surface of the substrate made of aluminum or aluminum alloy. By forming a two-layered film of the electroless black Ni plating layer, a surface treatment layer for a turbo molecular pump with improved corrosion resistance and emissivity can be obtained. In this case, corrosion resistance is mainly handled by the electroless Ni plating layer, and thermal radiation is handled by the electroless black Ni plating layer. That is, the electroless Ni plating layer compensates for the low thermal emissivity of the electroless Ni plating layer, and the electroless Ni plating layer compensates for the low corrosion resistance of the electroless black Ni plating layer. Can be used. In addition, since both layers are metal plating layers, unlike the conventional case of coating with an epoxy resin, it is resistant to a plasma environment such as oxygen plasma and inexpensive coating is possible.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. The surface treatment layer shown as an embodiment constitutes a moving blade or a stationary blade of a turbo molecular pump used in a semiconductor manufacturing system.
[0014]
The surface treatment layer shown as an embodiment of the present invention is a treatment in a temperature range of 70 to 100 ° C. by immersing a base material made of aluminum or an aluminum alloy in a treatment liquid (heating aqueous solution) containing a fluorine compound and ammonium silicofluoride. By doing so, as shown in FIG. 1, the film | membrane 12 of a fluorine compound is formed in the surface of the base material 11 which consists of aluminum or an aluminum alloy.
[0015]
As the treatment liquid (heating aqueous solution) used here, 0.1 to 20 parts by weight (preferably 0.2 to 15 parts by weight) of a fluorine compound and 0.05 to 0.05 part of ammonium silicofluoride with respect to 100 parts by weight of water. It is good to use what contains 15 weight part (preferably 0.1-10 weight part). Further, as the fluorine compound, a fluorine compound other than ammonium silicofluoride ((NH ₄ ) ₂ SiF ₆ ) is used, and it is preferable to use a silicofluoride salt, particularly magnesium fluorosilicate MgSiF ₆ · 6H ₂ O. Other examples include silicon fluoride such as zinc silicofluoride (ZnSiF ₆ .6H ₂ O), potassium silicofluoride (K ₂ SiF ₆ ), sodium silicofluoride (Na ₂ SiF ₆ ), manganese silicofluoride (MnSiF ₆ · 6H ₂ O), and the like. Salt, borofluoride, zirconium fluoride, titanium fluoride, and the like. Among these fluorine compounds, silicofluoride salts are preferably used, and magnesium silicofluoride, manganese silicofluoride, and the like are particularly preferably used.
[0016]
By using such a treatment liquid, a uniform thin film having excellent corrosion resistance and thermal radiation can be formed on the surface of aluminum or an aluminum alloy. Incidentally, the emissivity ε can be set to about 0.7 to 0.8. Further, the above-mentioned film can be made very thin (about 3 μm), and the dimensional change of the parts can be reduced. Therefore, it is not necessary to design the dimensions of the substrate in consideration of the film thickness in advance. Further, since the above film is not porous (has no pores), there is no fear of degassing even when it comes into contact with the reactive gas. Moreover, since the durability against oxygen plasma is high, and a film can be formed just by immersing in the above-mentioned treatment solution, an excellent surface treatment layer for a turbo molecular pump can be provided very easily and inexpensively.
[0017]
In the treatment liquid, when the fluorine compound is less than 0.1 parts by weight, or when the ammonium silicofluoride is less than 0.05 parts by weight, the reaction becomes slow and the treatment time becomes long. . On the other hand, when the fluorine compound exceeds 20 parts by weight, or when the ammonium silicofluoride exceeds 15 parts by weight, dissolution becomes difficult, which is not preferable.
[0018]
In addition, the temperature of the treatment liquid when dipping a substrate made of aluminum or an aluminum alloy is usually within a range of 70 ° C to 100 ° C, preferably within a range of 75 ° C to 99 ° C, more preferably 80 ° C to It is desirable to set within the range of 98 ° C. When the temperature of the treatment liquid is low such that it is less than 70 ° C., the reaction becomes slow and the treatment time becomes long. On the other hand, when the temperature of the processing liquid is high such that it exceeds 100 ° C., evaporation of the processing liquid increases, which is not preferable. Regarding the processing time, since the film formation reaction is completed in about 1 minute, soaking for about 2 minutes is sufficient for the surface treatment. However, since this film has a protective action, no problem arises even if it is immersed for 30 minutes or more after it is once formed.
[0019]
As shown in FIG. 2, the surface treatment layer shown as a reference example is a two-layer coating 24 of an electroless Ni plating layer 22 and an electroless black Ni plating layer 23 on the surface of a base 21 made of aluminum or an aluminum alloy. Is formed. In this surface treatment layer, an electroless Ni plating layer 22 is formed on the base, and an electroless black Ni plating layer 23 is formed thereon.
[0020]
Thus, by forming the two-layered film 24 of the electroless Ni plating layer 22 and the electroless black Ni plating layer 23 on the surface of the aluminum base material 21, the surface treatment layer that improves both the corrosion resistance and the emissivity. Can be provided. In this case, the electroless Ni plating layer 22 may compensate for the low thermal emissivity of the electroless Ni plating layer 22, and the electroless Ni plating layer 22 may compensate for the low corrosion resistance of the electroless black Ni plating layer 23. Therefore, it is possible to obtain a material for a turbo molecular pump that takes advantage of both and has high corrosion resistance and high emissivity. In addition, since both layers are metal plating layers, unlike the conventional case of coating with an epoxy resin, it is resistant to a plasma environment such as oxygen plasma and inexpensive coating is possible.
[0021]
【The invention's effect】
As described above, the surface treatment layer for the turbo molecular pump according to the first aspect of the present invention is obtained by immersing a base material made of aluminum or an aluminum alloy in a treatment liquid containing a fluorine compound and ammonium silicofluoride, and having a temperature of 70 to 100 ° C. By treating in the above temperature range, a film of a fluorine compound is formed on the surface of the substrate, so that both corrosion resistance and emissivity can be improved. In addition, since the film can be thinned, the dimensional change of the parts can be reduced, and it is not necessary to design the dimensions of the base material in advance by considering the film thickness. Moreover, since the said film | membrane is not porous, there is no worry of degassing even if it contacts with reactive gas. Moreover, since the durability against oxygen plasma is high and a film can be formed only by immersing in the above-described processing solution, there are advantages that can be realized extremely easily and inexpensively.
[0022]
The surface treatment layer for the turbo molecular pump of the reference example is formed by forming a two-layered film of an electroless Ni plating layer and an electroless black Ni plating layer on the surface of a substrate made of aluminum or an aluminum alloy. Therefore, both corrosion resistance and emissivity can be improved. In addition, since both layers are metal plating layers, they are resistant to a plasma environment such as oxygen plasma and can be coated inexpensively.
[Brief description of the drawings]
1 is an enlarged cross-sectional view of the surface treatment layer of the implementation of the invention.
FIG. 2 is an enlarged cross-sectional view of a surface treatment layer of a reference example .
FIG. 3 is a schematic configuration diagram of a turbo molecular pump.
[Explanation of symbols]
11, 21 Base material made of aluminum or aluminum alloy 12 Fluorine compound coating 22 Electroless Ni plating layer 23 Electroless black Ni plating layer 24 Double layer coating

Claims (1)

  A surface treatment layer formed on a moving blade or stationary blade that is an internal part of a turbo molecular pump, wherein a substrate made of aluminum or an aluminum alloy is immersed in a treatment liquid containing a fluorine compound and ammonium silicofluoride. A turbo molecular pump characterized in that a fluorine compound film is formed on the surface of the base material by treatment in a temperature range of ~ 100 ° C, and the emissivity ε is set to about 0.7 to 0.8. Surface treatment layer.

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