JP2975120B2 - Method of forming ceramic film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a two-layer ceramic film capable of imparting excellent electrical characteristics with high volume resistivity and dielectric breakdown voltage to metal parts of general machinery, high vacuum equipment and electronic equipment. It is.

[0002]

Heretofore, the like to the metal substrate and various vapor phase plating has been applied roughly in the vapor phase plating, PVD, primarily physical reaction (Physical Vap o
CVD for forming a r Deposition) and the film by a chemical reaction (Chemical Vap o r De
position). However, these methods, both the film itself is compositionally, have excellent characteristics for a structurally intact, is thin and the volume resistivity of the vapor phase plating and breakdown voltage, etc. is low, electricity There was a problem in imparting proper characteristics.

[0003] Further, in vapor phase plating, although the characteristics of the film itself are excellent, it is generally desired from the viewpoint of work efficiency that the film formation speed is slow, the film is thinner, and a desired function can be achieved. On the other hand, as a method of forming a ceramic film on a metal substrate or the like, an anodic spark discharge method is known (Japanese Patent Publication Nos. 58-17278, 59-45722, and 60-12438). When a ceramic film is formed, the corrosion resistance is improved, but there is a problem that the volume resistivity, the dielectric breakdown voltage and the like are not sufficient.

[0004]

SUMMARY OF THE INVENTION The present invention provides a method for efficiently forming a ceramic film having excellent electrical properties such as volume resistivity and dielectric breakdown voltage on a substrate surface by utilizing a vapor phase plating method. The purpose is to do.

[0005]

SUMMARY OF THE INVENTION The present invention provides a method for forming a first ceramic film, in which ceramic particles are chemically bonded to a substrate, on a substrate by an anodic spark discharge method, and then forming a vapor phase on the first ceramic film. It has been made based on the knowledge that when the second ceramic film is formed by the plating method, the formed multilayer film exhibits excellent electric characteristics, and the above problem can be solved efficiently.

That is, the present invention provides a method for forming a ceramic film, comprising forming a ceramic film by vapor phase plating on a substrate on which a ceramic film has been formed by an anodic spark discharge method.

In the present invention, as the anodic spark discharge method for forming a ceramic film on a substrate, an aqueous solution containing a water-soluble or colloidal silicate and / or an oxyacid salt or ceramic fine particles suspended in the aqueous solution. A method in which a substrate is immersed in an electrolytic bath to perform anodic spark discharge is preferred.
Here, as the silicate, the general formula M ₂ O · nSiO ₂ (M
Represents an alkali metal, and n represents an integer of 0.5 to 100), such as sodium silicate, potassium silicate, and lithium silicate; Colloidal silica and the like can be mentioned. Examples of the oxyacid salt include one or a mixture of two or more of tungstic acid, stannate, molybdic acid, borate, aluminate, phosphate and the like. In the present invention, the above silicate or oxyacid salt alone or 2
It can be used as a mixture of more than one species or as a mixture of both.

[0008] Further, various insoluble and dispersible ceramic fine particles may be suspended in the electrolytic bath. For example, Al
₂ O ₃ , Al (OH) ₃ , SiO ₂ , 3Al ₂ O ₃ · ₂ SiO ₂ , TiO ₂ , Zr
O ₂ , partially stabilized zirconia, stabilized zirconia, Cr
Oxide ceramics such as ₂ O ₃ and SiC, TiC, TiN, Ti
Non-oxide ceramics such as B, ZrB, BN, WC, WSi ₂ , and MoSi ₂ can be mentioned. These can be used alone or as a mixture of two or more of them (Japanese Patent Application Nos. 1-228639 and 2-54827).

The concentration of the water-soluble or colloidal silicate and / or oxyacid in the aqueous solution used for the electrolytic bath is 5 g /
l or more is preferable, and 25 to 200 g / l is suitable.
In particular, in the case of the oxyacid salt, when the concentration is close to the saturation, the film formation speed increases most. However, the phenomenon that the formed film becomes non-uniform with the increase in the concentration is apt to occur, so the above concentration is preferably used. The pH of the aqueous solution is arbitrary, but is 3 to 13.
It is better to set it to 5.

The substrate on which a ceramic film can be formed by spark discharge according to the present invention includes metal substrates such as aluminum and its alloys, zirconium, titanium, niobium, magnesium and its alloys. In addition, the shape of the base may be any shape such as a flat plate, a line, a rectangular parallelepiped, and a sphere.

Usually, when a spark discharge film is formed on such a metal substrate, it is not particularly necessary to perform a pretreatment, but it is desirable that the metal substrate be sufficiently cleaned by degreasing, etching, pickling or the like. As the cathode, an insoluble electrode such as iron, stainless steel, and nickel is used. The bath temperature for spark discharge is 5-9.
The temperature is preferably 0 ° C, more preferably 15 to 60 ° C. This is because at low temperatures, the film formation speed due to spark discharge is slow, while at high temperatures, the formed film tends to be non-uniform. Current density may be carried out in 0.2~20A / dm ^2, preferably 1-5A / dm ^2.

The film thickness of ceramics formed by spark discharge as a base for vapor phase plating can be arbitrarily determined.
The above is good, to fully demonstrate the characteristics of vapor phase plating
It is preferably from 0.01 to 3 μm, more preferably from 0.1 to 1 μm.
μm.

As a vapor phase plating method to be performed next, any method can be used as long as a high quality ceramic film can be formed on the first film. For example,
PVD includes reactive ion plating and reactive sputtering, and CVD includes thermal CV.
D, plasma CVD. Of these, it is preferable to use the method described in JP-A-2-205684.

The film thickness may be any thickness that can exhibit the performance of the vapor phase plating film, and is 0.01 μm or more, preferably 0.0 μm or more.
The thickness is 1 to 5 μm, more preferably 0.1 to 3 μm. or,
The ratio of the thickness of the first film formed by the anodic spark discharge method to the thickness of the second film formed by the vapor phase plating method can be arbitrarily determined, but is preferably 1/1 to 1/30.

As the type of the ceramic film formed by the vapor phase plating method, any ceramic film such as an oxide type or a non-oxide type may be used. For example, oxides include Al ₂ O ₃ , SiO ₂ , TiO ₂ , ZrO ₂ , Cr ₂ O _{3 and the} like, and non-oxides include SiC, TiC, TiN, B
N, Si ₃ N ₄ and CrN can be mentioned. Among these, an oxide-based material that can easily form a high-quality film on the anode spark discharge film serving as a base is more preferable.

The composition of the first ceramic film formed by the anodic spark discharge method and the composition of the second ceramic film formed by the vapor phase plating method may be the same, similar, or different. When the two compositions are the same or similar, a ceramic film having more excellent adhesion can be obtained.

[0017]

According to the present invention, a ceramic film having excellent electrical properties such as volume resistivity and dielectric breakdown voltage can be efficiently formed on the surface of a substrate by utilizing a vapor phase plating method. Further, according to the method of the present invention, there is obtained an advantage that salt water resistance, which is a problem for a film formed by vapor phase plating, can be improved.

Accordingly, the ceramic film formed on the substrate by the method of the present invention can be used not only as an electrical material such as an insulated wire, an electric part, a semiconductor , a printed circuit board or a flexible printed circuit board, but also as a salt water resistant material. It is expected to improve corrosion resistance because of its superiority, so that it can be applied to a protective film of a semiconductor manufacturing apparatus chamber using an active gas or a component used inside. Other than that, although a ceramic film is formed on a substrate, it can be widely used for general purposes.

Next, the present invention will be described with reference to examples.

[0020]

【Example】

Example 1 An aluminum plate (100 mm x 100 mm x 0.5 mm) was cleaned by degreasing, alkali etching, and acid activation treatment, and then used as an anode, a stainless steel plate as a cathode, and K
It was spark discharge in a solution of _{2 O · nSiO 2 200g / l} . In electrolysis at a liquid temperature of 30 ° C., 1 A / dm ² , and 2 minutes and 30 seconds, the electrolysis was performed at 0.
A spark discharge film composed mainly of 1 μm of SiO ₂ was formed. After the substrate on which the film has been formed is sufficiently washed with running water and purified water, it is sufficiently dried.
The vapor phase plating was performed using the vapor phase plating apparatus described in FIGS. 1 and 2 of JP-A-84. In this apparatus, a plasma flow extracted from an accelerated plasma electron beam source was formed into a sheet shape by a magnet, and a ceramic film was formed on a substrate facing the sheet-like plasma flow. That is, after evacuating the vacuum chamber to a pressure of 3 × 10 ^-5 Torr, Ar was introduced into the accelerated plasma electron beam source as a carrier gas for plasma, and electricity was supplied to the composite cathode in the beam source to heat the main cathode. Then, a large current of 50 A / cm ² was taken out, and plasma was generated between the anode and the anode. Next, SiH ₄ gas was introduced as a raw material gas from an introduction pipe, and oxygen gas was introduced as a reaction gas from another introduction pipe at a flow rate ratio of 1:10. At this time, the pressure in the vacuum chamber was 7 × 10 ⁻³ Torr. After the source gas and the reaction gas were continuously introduced for 10 minutes to form a silicon oxide film on the substrate, the introduction of the gas was stopped and the discharge was terminated.

When the thickness of the silicon oxide film formed by vapor phase plating was measured by a surface roughness meter, it was 0.8 μm.

Example 2 A silicon oxide film was formed under the same conditions as in Example 1 except that the source gas and the reaction gas were introduced for 20 minutes. The thickness of the silicon oxide film formed by vapor phase plating was measured with a surface roughness meter and found to be 1.5 μm.

Example 3 An aluminum plate cleaned and formed in the same manner as in Example 1 was used.
Na_FourP_TwoO₇・ 10H_TwoO 60g / l aqueous solution_TwoO_ThreeFine grain
Child (manufactured by Nippon Denko KK, trade name, ND-802, average grain
In a solution in which 50 g / l was suspended, the cathode diameter was 0.7 μm.
Using a stainless steel plate, liquid temperature 30 ° C, 1A / dm^TwoCurrent
The current was passed for 60 minutes at the density. Al_TwoO_ThreeAnd Cr_TwoO _ThreeComposed of
A spark discharge film of 11 μm was formed. The above first coating
Under the same operating conditions as in Example 1 on the substrate on which
To form a silicon oxide film by vapor phase plating.
Was.

Comparative Example 1 The procedure of Example 1 was repeated except that the first film was not formed by the anodic spark discharge method and the film thickness was formed to the thickness shown in Table 1 by the vapor phase plating method. Then, a ceramic film was directly formed on the cleaned aluminum plate by a vapor phase plating method.

Comparative Example 2 The procedure of Example 1 was repeated, except that the second film was not formed by the vapor phase plating method and the film thickness was formed to the thickness shown in Table 1 by the anodic spark discharge method. A ceramic film was formed directly on the cleaned aluminum plate by the anodic spark discharge method.

Comparative Example 3 The same procedure as in Example 3 was carried out except that the second film was not formed by the vapor phase plating method and the film thickness was formed to the thickness shown in Table 1 by the anodic spark discharge method. A ceramic film was formed directly on the cleaned aluminum plate by the anodic spark discharge method.

Table 1 shows the thickness and properties of the film formed by the above method. The characteristics in the table were measured by the following methods. Volume resistivity Measured at a test voltage of 50 V by using a super insulation resistance meter TR8601 (Takeda Riken Kogyo Co., Ltd.) according to a method according to JIS C2103 varnish test method for electrical insulation. Dielectric breakdown voltage Measured with a breakdown voltage meter B-5110AF (manufactured by Faith Co.) according to JIS C2110, a method in accordance with the varnish coating test method of the dielectric strength test method of solid electrical insulating materials.

Flex resistance A test was conducted using a mandrel having a diameter of 2 mm according to a method according to JIS K5400 paint general test method, and the evaluation was made by the following evaluation. ：: almost no peeling due to bending, △: あ り present, ×: complete peeling from 〃, salt water resistance 5% salt spray test (JIS-Z-2371) was performed for 500 hours, and the white rust generation rate (%) was visually determined. did.

[0029]

[Table 1]

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C23C 28/04

Claims (1)

(57) [Claims] 1. A method for forming a ceramic film, comprising forming a ceramic film by vapor phase plating on a substrate on which a ceramic film has been formed by an anodic spark discharge method.