JP2001234324A - Method for passivation treatment of metal surface - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for passivation treatment of a metal surface, having no effect on a corrosion-resistant and non-heat-resistant packing and excellent in workability. SOLUTION: Gaseous ozone of 10-50 vol.% gaseous ozone concentration is allowed to act on a metal surface at 60-150 deg.C to apply passivation treatment to the metal surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating a metal surface used in a facility requiring a clean fluid, such as a semiconductor production facility or a bio-pharmaceutical raw material production facility.

[0002]

2. Description of the Related Art In recent years, in the semiconductor manufacturing and manufacturing industry, the integration and performance of electronic components have advanced, and ultra LSIs with a minimum processing dimension of the order of submicrons have been manufactured. Under these circumstances, the raw materials used in the production of electronic components such as semiconductors are not only highly purified, but also fine particles mixed in from the equipment and piping that constitute the gas supply system as raw materials.
(Impurities) and gaseous impurities released from the member surface also pose problems. Therefore, there has been proposed an apparatus in which an oxidation passivation film is formed on a metal surface constituting a piping or equipment in such a facility so as to suppress the release of impurities from the metal surface.

Conventionally, techniques for forming an oxide passivation film on a metal surface include, for example, Japanese Patent Application Laid-Open No. 5-287496,
There is one disclosed in Japanese Patent Application Laid-Open No. 9-195031. In the former, an oxidation passivation film is formed on the surface of stainless steel under a temperature condition of 150 to 300 ° C. in a dry oxygen atmosphere having an ozone content of 0.5 to 10 vol%,
The latter one has an ozone gas concentration of 50% or more (remaining oxygen)
High-concentration ozone gas is enclosed in equipment and piping to form an oxide passivation film on the metal surface.

[0004]

In the prior art in which a passivation film is formed using ozone gas of 10 vol% or less, the processing temperature is set to a temperature of 150 to 300 ° C., but this temperature range is There is a problem that it cannot be applied to a device including a non-heat resistant material having corrosion resistance such as silicon packing. In addition, since heating must be performed to a relatively high temperature of 150 to 300 ° C., there is a problem that a heating device such as a heating furnace for heating equipment, piping, and the like becomes large.

On the other hand, the latter using high concentration ozone of 50 vol% or more (remaining oxygen) cannot be processed at a high temperature due to the characteristics of ozone. There was a little inferior.

In view of the above, the present invention focuses on such points as pipes and equipment using ozone gas, which have excellent workability without affecting the corrosion-resistant but non-heat-resistant packing, and the metal of equipment. It is an object of the present invention to provide a method for passivating a surface.

[0007]

According to the present invention, an ozone gas having an ozone gas concentration of 10 to 50 vol% (remaining oxygen) is allowed to act on a metal surface in a temperature range of 60 to 150 ° C. The present invention is characterized in that a passivation treatment is performed on a metal surface.

[0008]

According to the present invention, the ozone gas concentration is 10 to 50% by volume in a heating state at a relatively low temperature of 60 to 150 ° C.
Since the (remaining oxygen) ozone gas is applied, the packing does not have a thermal effect, and the heating device may be a simple device such as an electric heater. In addition, if the ozone gas concentration is 10 to 50 vol% (remaining oxygen), the ozone gas can be used in a relatively low temperature heating state of 150 ° C. or less, the reactivity with the metal surface is increased, and the workability is improved.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Using a SUS316L electropolishing tube as a sample, the ozone gas concentration is changed on the inner surface thereof, and the ozone gas is circulated for 60 minutes while the heating temperature is changed to form an oxidation passivation film on the inner surface. The sample on which the oxidation passivation film was formed was exposed to 0.3 MPa, 100% hydrogen chloride gas for 6 days, and then immersed in pure water to detect the amount of eluted metal. The result is shown in FIG.

As can be seen from FIG. 1, the lower the heating temperature, the larger the amount of eluted metal, and at the same temperature, the lower the ozone concentration, the higher the amount of eluted metal.
When the heating temperature is 100 ° C. and 150 ° C., the elution amount is substantially constant when the ozone concentration is higher than 10 vol%. Then, in a so-called normal temperature region where the heating temperature is lower than 50 ° C., ozone does not sufficiently react, and it is determined that a stable metal oxide film is not formed with a sufficient thickness. Here, the ozone concentration is the ozone concentration in oxygen.

FIG. 2 is a diagram showing the ozone concentration under atmospheric pressure and the danger of explosion. When an ozone gas having a changed ozone concentration (the rest is oxygen) is irradiated to a heating stage at 300 SCCM, a decomposition explosion occurs. It is checked whether or not.

As can be seen from FIG. 2, in a temperature range of 150 ° C. or less, an ozone gas concentration of 50 vol.
When the ozone gas concentration is lower than 10 vol%, no decomposition explosion occurs in a temperature range of 400 ° C. or lower.

As a result, the ozone concentration (remaining oxygen) is 10 to
It can be seen that a stable oxidation passivation film can be formed by applying 50 vol%, desirably 20 to 30 vol% of ozone gas to the metal surface in a temperature range of 60 to 150 ° C.

In the above embodiment, the untreated material is S
Although a US316L electropolishing tube was used, the present invention can be applied to all metals without choosing the surface roughness or material. In the present invention, the piping system is used in a concept that includes not only piping, but also equipment between the ozone gas storage facility and the ozone gas use facility.

The present invention can also be used for processing flanges, chamber parts and the like as a single unit.

[0016]

According to the present invention, an ozone gas having an ozone gas concentration of 10 to 50 vol% (remaining oxygen) is applied in a heating state at a relatively low temperature of 60 to 150 ° C. Even a device using packing does not affect the packing material thermally, and the heating device may be a simple device such as an electric heater. As a result, a reliable oxidation passivation film can be formed using a small and inexpensive apparatus.

Further, the ozone gas concentration is 10 to 50 vol%
If the ozone gas is (remaining oxygen), it can be used in a relatively low temperature heating state of 150 ° C. or less, the reactivity with the metal surface is increased, and the workability can be improved.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between an ozone concentration and an amount of eluted metal when an ozone treatment temperature is changed.

FIG. 2 is a diagram showing the ozone concentration under atmospheric pressure and the danger of explosion.

Claims (2)

[Claims] 1. A passivation of a metal surface configured so that an ozone gas having an ozone gas concentration of 10 to 50 vol% acts on a metal in a temperature range of 60 to 150 ° C. to passivate a gas contact surface of the metal surface. Processing method. 2. The method for passivating a metal surface according to claim 1, wherein the concentration of the ozone gas is 20 to 30 vol%.