JPS63223162A - Formation of crystalline transparent alumina film by ion plating - Google Patents

Abstract

PURPOSE:To easily form a crystalline transparent alumina film by high frequency excitation type reactive ion plating, by using Al as a metal to be evaporated and oxygen as a reactive gas and carrying out ion plating without heating a body to be ion plated. CONSTITUTION:A substrate is set in a high frequency ion plating device and the air in the device is replaced with a gaseous oxygen atmosphere. The internal pressure of the device is regulated to a prescribed degree of vacuum and high purity Al as an evaporating source is melted by heating. Prescribed voltage and high frequency are then impressed on the substrate without heating the substrate to form an alumina film on the substrate. Pref. conditions during the film formation include about 100-800W high frequency power, about -0.1--0.5kV bias voltage impressed on the substrate and about 5X10<-4>-9X10<-4>Torr degree of vacuum in the gaseous oxygen atmosphere.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is directed to the production of crystalline materials by ion plating that can easily form a crystalline transparent alumina film on a base material of an appropriate material by a high frequency excited ion plating method. The present invention relates to a method for forming a transparent alumina film.

[Prior Art] Alumina has excellent hardness, strength, abrasion resistance, oxidation resistance, heat resistance, corrosion resistance, and electrical insulation, and has advantages such as being cheaper than TiN, TiC, etc. It is something. Therefore, it has been proposed to use it as a coating for tools and as an insulating film and a protective film for electronic materials.

However, conventional methods for producing alumina coatings include anodic oxidation, CVD, and PVD, and alumina coating technology for tools using the CVD method has been put into practical use; There are restrictions on the material of the workpiece, and its uses are limited, such as when it is used as a carbide tool. Further, as a method of the PVD method, Japanese Patent Application Laid-Open No. 61-79760 discloses a method of forming an alumina film by arc discharge type ion plating, which is a type of reactive ion plating method. However, this method also involves heating the workpiece to 500°C to perform the ion plating treatment, so it cannot be applied unless the workpiece is made of a material that is heat resistant at or above the heating temperature. The film that forms is an amorphous black film (Aldopia; April issue,
pp. 48-52 (198G) and Shizuoka Technology Center Research Report, Nα29, pp. 115-120, (1985)
) There was a pause.

[Problems to be Solved by the Invention] In the method described in the above-mentioned patent publication, there are restrictions on the material of the object to be treated as described above, and the alumina produced is amorphous. However, amorphous alumina has various properties such as withstand voltage and ionic conductivity that are inferior to crystalline alumina, and if a crystalline alumina film can be obtained, it would be possible to provide a product with better properties and its uses. Can be expanded.

The object of the present invention is to provide a means for easily forming a crystalline alumina film by ion plating.

[Means for Solving the Problems] In order to solve the above problems and achieve the above objectives, the present inventors have conducted extensive research, replaced the ion plating method with another method, and heated the object to be processed. The present invention was completed based on the discovery that the object could be achieved by performing ion plating treatment without the use of ion plating. That is, the present invention provides a crystalline transparent alumina film formed by ion plating in which the ion plating process is performed without heating the object to be processed, using aluminum as the evaporated metal and oxygen as the reaction gas in the high frequency excitation type reactive ion plating method. This is the formation method.

The material to be treated that can be used in the present invention is not particularly limited as the material is treated without heating, and organic materials such as plastics can also be used, and metal materials such as aluminum and steel materials can be used. Alternatively, any material (including composite materials and laminated materials), such as inorganic materials such as glass, carbon, and ceramics, and any shape may be used.

The evaporated metal is aluminum, typically 99.99
High purity aluminum of %A1 or higher is placed in a crucible and melted and evaporated with an electron beam.

In this case, the electron beam power is 8-20 KV, 40
0 to 450 mA, and the aluminum evaporation rate is adjusted to be about 10 to 20 A'//sec as usual.

The reaction gas is oxygen, and it is preferable to use high-purity oxygen gas for semiconductors, but it is also possible to use this oxygen gas mixed with argon gas as appropriate to achieve a suitable sputtering effect.

The inside of the apparatus is evacuated during the process, and when oxygen gas is used alone, the vacuum degree is preferably 5X10-' to 9x1O-'Torr at the above-mentioned aluminum evaporation rate.
Below 5X10-'Torr, the amount of oxygen to achieve the stoichiometric ratio of A1□03 is insufficient, resulting in aluminum-rich Al2O3. 9 x 10-' Torr
On the contrary, if it exceeds 100%, it becomes rich in oxygen.

On the other hand, when the degree of vacuum deteriorates, the mean free path of ions and atoms becomes shorter, the film formation rate decreases, and C adversely affects the operation of the electron beam.

When using a mixed gas of oxygen gas and argon gas, set to 0.
2 Partial pressure 4.5xlO-' ~ 8.5xlO-' Tor
It is preferable that the partial pressure of r and r is approximately 0.5×10 −' Torr.

The high frequency power is 100 to 800W, preferably 200W.
-400W, because if it is less than 100W, it is difficult to maintain the discharge, and if it is more than 800W, the temperature inside the vacuum chamber will rise. In this case, 200~
In the range of 400 W, the ionization of the evaporated metal, especially by high-frequency discharge, is best expressed.

The bias voltage is in the range -0,i- to -0,5 KV, preferably -0,1 to 0,3 KV (7).
, IKV or less, the appropriate sputtering effect will not be expressed, and if it is -0.5KV or more, sparks will occur because Al2O3 produced by ion plating is an insulator.
It is preferable to suppress the voltage applied to the substrate as much as possible since it may cause damage to the film quality and pinholes.

The thermionic current is 10-20 A and is required to maintain aluminum ionization.

Prior to the ion plating process, the conventional ion bombardment process is performed, and the surface of the object to be processed is cleaned by hot trichloride cleaning or acetone ultrasonic cleaning, and then placed in a vacuum chamber. , 2X10 ~
A voltage of 0.1 to 0.5 KV is applied as a cathode in an argon atmosphere under a vacuum of 7x1O” Torr.
Discharge cleaning is performed for N-10 to 20 minutes while applying a high frequency wave of 00 to 400 W.

The processed product thus produced according to the present invention is
In addition to the conventional uses of opaque alumina coatings, it can be used for various new uses depending on the object to be treated. For example, it can be applied to insulating films for semiconductor devices and functional devices, corrosion-resistant transparent protective films, abrasion-resistant transparent protective films, heat-resistant protective films, glabella protective films, barrier films, multilayer antireflection films, and reductive absorption films. Furthermore, it can exhibit properties at a higher level than amorphous materials, and can be applied to plastics and the like that are not heat resistant, so it is expected to have a wide range of applications.

[Effects of the Invention] The present invention uses a high-frequency excitation type reactive ion plating apparatus to perform reactive ion plating processing without heating the object to be processed. A transparent alumina film can be formed very easily, especially in ion plating treatment, with high frequency power of 200 to 400 W, bias voltage of object to be treated -0.1 to 0.5 Kv, degree of vacuum 5 x 10-'
When processing under the conditions of ~9 x 10-' Torr, a film with uniform and stable quality can be obtained, and in addition to its conventional use as an alumina film, new uses for the alumina film can be expanded as a crystalline transparent film. Excellent effects are recognized.

[Example] Next, examples of the present invention will be described.

Example 1 Aluminum plate with purity 99.0% AI (plate thickness 0.1nv)
n) was used as an object to be treated, and pretreatments such as degreasing with trichlorethylene and ultrasonic cleaning with acetone were performed.

This was placed in a high-frequency ion plating apparatus, and after being subjected to ion bombardment in an argon gas atmosphere at a vacuum degree of 5 x IF' Torr, it was subjected to ion plating.

While replacing the inside of the device with an oxygen gas atmosphere, the degree of vacuum is increased to 6X10.
Torr, 99.99% pure aluminum was heated and melted with an electron beam of 10 KV and 400 mA, and then -0, 2
By applying a bias voltage of KV and a high frequency of 400 W, the alumina film formation was controlled by a film formation monitor, and the film thickness was 1.
Samples were prepared in which films of μm (sample B) and 3 μm (sample C) were formed.

Regarding the obtained sample b, the crystal structure of the formed film was analyzed by X-ray diffraction. As a result, as shown in FIG. 1, a peak of γ-AI203 was detected within the peak of A1 of the substrate, and it was confirmed that the film was crystalline.

Also, the resistivity measured for sample C is 2×1012Ω
・l, Vickers strength was 2000. Furthermore, an abrasion resistance test was conducted using a Suga abrasion tester at a load of 400 g using SiC abrasive paper #1000, including an untreated aluminum material (sample C).

The results are shown in FIG. 2, and it was found that a good wear-resistant film was obtained.

Example 2 Ion plating treatment was carried out under the same conditions as in Example 1, except that the object to be treated was a glass plate, to form an alumina film with a thickness of 1 μm. The transparency of the obtained film was determined by transmittance measurement using a spectrophotometer. The results are shown in Figure 3. In the figure, the dotted line (A) is the transmittance of the glass plate to the air, and the solid line (8) is the transmittance of the glass plate with the alumina film to the air.
In the wavelength range of 800 nm, it showed almost the same transmittance as glass, and it was recognized that an optically transparent film was formed.

Comparative Example 1 A film was formed under the same conditions as in Example 1 except that the substrate voltage was -1 and OKV. As a result of X-ray diffraction of the obtained film, γ-A 1203 was not detected and it was recognized that the film was amorphous.

Comparative Example 2 A film was formed under the same conditions as in Example 1, except that the object to be treated was heated to 400°C. As a result of X-ray diffraction of the obtained film, γ-^f203 was not detected and it was recognized that the film was amorphous.

[Brief explanation of drawings]

FIG. 1 is an X-ray diffraction diagram showing the X-ray diffraction results of the alumina film obtained by the method of the present invention, with 2θ (degree) on the horizontal axis and intensity on the vertical axis. Figure 3 shows the abrasion resistance test results of alumina coatings, with the number of wears (times) on the horizontal axis and the wear J2L (■) on the vertical axis.
The figure shows the results of measuring the transmittance of an alumina film obtained by the method of the present invention, with wavelength (nm) plotted on the horizontal axis and transmittance (%) plotted on the vertical axis.

Claims (1)

[Claims] 1) In the radio frequency excitation type reactive ion plating method, aluminum is used as the evaporated metal, oxygen is used as the reaction gas,
A method for forming a crystalline transparent alumina film by ion plating, characterized in that the ion plating treatment is performed without heating the object to be treated. 2) Ion plating processing conditions: high frequency power of 100 to 800 W, object bias voltage of -0.1 to -
0.5KV, degree of vacuum 5x10^-^4~9x10^-^
A method for forming a crystalline transparent alumina film by ion plating according to claim 1, which is carried out under a 4 Torr oxygen gas atmosphere.