JP2517727B2 - Method for manufacturing stainless steel member for semiconductor manufacturing equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a stainless steel member used as a constituent member of a semiconductor manufacturing apparatus, and more specifically, to smoothness and cleanliness necessary for obtaining a high quality product. The present invention relates to a method for manufacturing a stainless steel member having excellent properties. In the present specification, a pipe member will be particularly taken up as the stainless steel member to explain the manufacturing method thereof, but the present invention can also be applied to the manufacture of other stainless steel members constituting the semiconductor manufacturing apparatus. Is.

[Prior Art] The development of technology in the semiconductor industry has been particularly remarkable in recent years, and high-performance products have been manufactured. For example, wiring intervals of semiconductor memory devices are required to have an accuracy of several microns, and even submicron accuracy. Therefore, the circuit may be short-circuited even if the fine particles or bacteria adhere to the wiring. Therefore, the gases and pure water used in the semiconductor manufacturing stage also need to be of ultra-high purity, and strict regulations are also imposed on the quality of the piping members that transfer these (hereinafter sometimes simply referred to as pipe materials). It is desired to supply a product provided with high cleanliness and smoothness on the inner surface of the pipe material. For this reason, in ultrapure water pipes, etc., there is no inconvenience in increasing the number of butt welding opportunities associated with the increase in capacity of semiconductor memory elements, and stainless steel materials that have better corrosion resistance than other materials are attracting attention. Bright annealing, cold working, for the purpose of smoothing and cleaning the surface,
Surface treatment methods such as chemical polishing and electrolytic polishing are adopted, and it is said that the one that has been subjected to electrolytic polishing is most effective.

[Problems to be Solved by the Invention] However, even in the case of stainless steel surface-treated by electrolytic polishing, heavy metal ions such as Fe, Cr, and Ni, which are the constituent elements, may elute, and semiconductor manufacturing equipment At present, no member has been obtained that sufficiently satisfies the above-mentioned highly required characteristics of the member for use.

The present invention has been made in view of such a situation, and an object thereof is to manufacture a semiconductor which is excellent in smoothness and cleanability of an inner surface of a pipe material and in which stainless steel constituent elements such as heavy metal ions are not eluted from the inner surface of the pipe. A point is to provide a method for manufacturing a stainless member for a device.

[Means for Solving Problems] The present invention heats a stainless steel member having a surface roughness Rmax of 1 μm or less by electrolytic polishing at 280 to 580 ° C. in an atmosphere having an oxygen content of 25% by volume or more. The gist is to form an oxide film on the surface of the member by performing an oxidation treatment.

[Operation] Although the present invention is configured as described above, in short, an oxide film is formed on the inner surface of the pipe material by adopting a treatment method that also has a function of removing impurities adhering to the inner surface of the pipe material.

In the present invention, first, the surface roughness of the stainless steel pipe material is set to Rmax: 1 μm or less by electrolytic polishing. Surface roughness Rmax: 1μm
If it exceeds, the oxide film to be formed lacks in denseness, so that the constituent elements of the pipe material are easily eluted and good corrosion resistance cannot be obtained.

Next, formation of an oxide film is carried out by heat treatment at a temperature of 280 to 580 ° C in an atmosphere containing 25% by volume or more of oxygen. As will be apparent from the examples described below, when the oxygen content is less than 25% by volume, the amount of oxygen is insufficient, and it becomes difficult to form a good oxide film, and when the heating temperature is less than 280 ° C, the temperature is low. It is too difficult to form a good oxide film. On the other hand, when the heating temperature exceeds 580 ° C, the oxide film grows too much, resulting in extremely fine cracks in the oxide film, resulting in insufficient corrosion resistance.

In the present invention, the heat treatment time is not particularly limited, but it is desirable to heat for 5 minutes or more to form the oxide film completely and satisfactorily.

Examples will be described below, but the present invention is not limited to the following examples, and it is within the technical scope of the present invention to appropriately change the design in view of the gist of the preceding and the following.

It hurts facilities electrolytic polishing to SUS316L stainless steel tube inner surface of the outer diameter of 12.7mm with _{Example] H 2 SO 4 -H 3 PO} 4 solution. Then, heat oxidation treatment was performed under various conditions shown in the left column of Table 1.
In the heating and oxidizing treatment, atmospheric gases having various oxygen contents were respectively introduced into the furnace, air was completely expelled, and then the tube material was put in and subjected to the heating treatment. The following tests were conducted on these materials.

(A) Elution metal amount measurement test After filling the inside of the sample pipe material with ultrapure water of> 18 MΩ · cm and keeping the whole pipe material at 80 ℃ for 30 days, elute in the ultrapure water in the pipe material. The total amount of metal deposited was determined by ion chromatography and induction plasma mass spectrometry. The test results are shown in the right column of Table 1. In Table 1, the total metal elution amount is
Sample No. 19 which was not subjected to thermal oxidation treatment after electrolytic polishing
The relative elution amount is shown when the elution amount of 1 is 1.

As is clear from Table 1, all of the invention examples No. 1 to No. 11 have a tube inner surface roughness of Rmax: 1 by electrolytic polishing in advance.
The metal elution amount is as electrolytically polished because a dense and highly protective oxide film is formed by the oxidation treatment under appropriate conditions in an atmosphere with an oxidation content of 30% or more. The corrosion resistance was 1/3 or less, which was excellent in corrosion resistance.

On the other hand, in Comparative Example No. 12, the heat oxidation treatment temperature was low, so that an oxide film was not formed sufficiently to obtain corrosion resistance in ultrapure water.

In No. 13, the heat oxidation treatment temperature was too high, and as a result, the oxide film grew too much and microscopic defects were introduced into the film, resulting in insufficient corrosion resistance.

In No.14, the surface roughness exceeded Rmax.1μm due to insufficient electrolytic polishing as a pretreatment, resulting in poor smoothness. Therefore, the surface area was relatively large and the work-affected layer was removed before electrolytic polishing. Therefore, the oxide film formed on the surface thereof had defects, and the corrosion resistance was insufficient.

In No. 15, the oxygen content in the heated oxidizing atmosphere is about 20%
Since it was (atmosphere), the formation of the oxide film was insufficient and the corrosion resistance was inferior to that of the examples of the present invention.

In No. 16, since the pretreatment was bright pickling annealing, the surface roughness was extremely rough and the corrosion resistance was insufficient.

No.17 and No.18 were mechanical polishing,
A work-affected layer is formed on the surface during polishing. The oxide film formed on the work-affected layer had many defects and could not have sufficient corrosion resistance.

In Nos. 19 to 21, since the heat oxidation treatment was not applied, the oxide film was not sufficiently formed and good corrosion resistance could not be obtained.

(B) Impurity element analysis test on the inner surface of the pipe by IMMA: The analysis results are shown in FIG.

In the figure, A and B are A: a tube material that has been subjected to a heat oxidation treatment at 450 ° C. for 10 minutes in an atmosphere having an oxygen content of 99.9% after the tube inner surface roughness Rmax: 0.6 μm by electrolytic polishing (the present invention example). ) B: After the inner surface roughness of the tube is set to Rmax: 0.5 μm by electrolytic polishing,
This is a pipe material (comparative example) that has been subjected to a heat oxidation treatment at 450 ° C for 10 minutes in an atmosphere with an oxygen content of about 20% (atmosphere).

As is clear from FIG. 1, in comparison with Comparative Example B, Inventive Example A had significantly less Na and Cl adhering to the surface and was excellent in surface cleanability.

(C) Investigation of the ratio of Cr element to the total amount of metal on the inner surface of the pipe by AES analysis: The investigation results are shown in FIG.

In the figure, A and B are A: After the inner surface roughness of the tube is set to Rmax: 0.4 μm by electrolytic polishing,
A pipe material that has been subjected to a heat oxidation treatment at 425 ° C. for 60 minutes in an atmosphere having an oxygen content of 99.9% (Example of the present invention) B: After the inner surface roughness of the pipe is set to Rmax: 0.3 μm by electrolytic polishing,
A pipe material that has been subjected to a heat oxidation treatment at 425 ° C. for 60 minutes in an atmosphere with an oxygen content of 20% (in air) (comparative example). As is clear from FIG. The ratio of Cr to the total amount of metals in the oxide film was high, which revealed that the corrosion resistance to corrosive gases was improved in addition to ultrapure water.

EFFECTS OF THE INVENTION Since the present invention is configured as described above, according to the method of the present invention, a stainless steel member for a semiconductor manufacturing apparatus, which is excellent in smoothness, cleanability, impurity elution resistance and corrosion resistance, is manufactured. be able to.

[Brief description of drawings]

FIG. 1 is a diagram showing the result of IMMA analysis in the example of the present invention, and FIG. 2 is a diagram showing the ratio of Cr to the total amount of metal on the inner surface of the tube by AES analysis.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Haruo Tomari, 355-27 Kamizume, Yoneda-cho, Takasago, Hyogo Prefecture (72) Fumihiro Sato 9-7-16 Suzurandaito-cho, Kita-ku, Kobe, Hyogo Prefecture

Claims (1)

(57) [Claims] 1. A stainless steel member having a surface roughness Rmax of 1 μm or less obtained by electrolytic polishing is subjected to a heat oxidation treatment at 280 to 580 ° C. in an atmosphere having an oxygen content of 25% by volume or more to oxidize the surface of the member. A method of manufacturing a stainless steel member for a semiconductor manufacturing apparatus, which comprises forming a film.