JPH0499862A - Formation of thin hard alumina film - Google Patents

Abstract

PURPOSE:To form a thin hard alumina film having smoothness on the surface of a substrate by fixing the substrate and specifying heating energy and the rate of film formation when a thin hard alumina film is formed on the surface of the substrate by adopting irradiation with ions and vapor deposition in combination. CONSTITUTION:When a thin hard alumina film is formed on the surface of a substrate in a vacuum vessel by adopting irradiation with ions and vapor deposition in combination, the substrate is fixed and irradiation with ions and vapor deposition are carried out with acceleration energy of >=20keV at >=200 deg.C. Compressive stress is increased and a thin hard alumina film having smoothness can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for forming a hard alumina thin film, and particularly relates to an improvement in the method for forming a hard alumina thin film by a dynamic mixing method that uses both ion irradiation and vapor deposition.

[Prior art and problems] Conventionally, a method has been used to form an alumina thin film on the surface of a substrate by a dynamic mixing method that uses both ion irradiation and vapor deposition while rotating the substrate in a vacuum container to homogenize the film quality. ing.

In order to put this alumina coating into practical use, if the strength of the alumina thin film itself is insufficient, attempts have been made to improve the mechanical properties by applying compressive stress.

The above-mentioned methods for applying compressive stress include the so-called bimetal effect, which takes advantage of the difference in thermal expansion between the substrate and the covering alumina thin film, and the use of phase transition in the alumina thin film to generate compressive stress inside the thin film. Methods of increasing strength are known.

However, with this method, it is difficult to form a sufficiently hard alumina thin film.

The present invention was made to solve the above-mentioned conventional problems, and aims to provide a method for forming a hard and smooth alumina thin film with improved compressive stress.

[Means for Solving the Problems] In the present invention, when forming a hard alumina thin film on the surface of a substrate in a vacuum container using both ion irradiation and vapor deposition, the substrate is kept stationary and the acceleration energy is set at 201 ceV or more. This is a method for forming a hard alumina thin film, characterized by performing ion irradiation and vapor deposition at a temperature of 200° C. or higher.

Examples of the substrate include Ni5Ni-based alloy, Ti, T
Various metals such as i-based alloys and SUS, glass, etc. can be used.

The reason why the acceleration energy of the ions is limited is that if the acceleration energy is less than 20 k e V, sufficient compressive stress cannot be applied to the inside, making it impossible to form a hard alumina thin film.

The reason for limiting the temperature during film formation is that the temperature is 20°C.
If the temperature is below 0°C, sufficient compressive stress cannot be applied internally,
This is because a hard alumina thin film cannot be formed.

[Function] According to the present invention, when forming a hard alumina thin film on the surface of a substrate in a vacuum container using both ion irradiation and vapor deposition,
While keeping the substrate stationary, the acceleration energy is increased to 20k.
By performing ion irradiation and vapor deposition at a temperature of 200° C. or higher and a temperature of 200° C. or higher, the compressive stress is improved and a hard and smooth alumina thin film can be formed. It is presumed that this hardening effect is due to the phenomenon described below.

In other words, the dynamic mixing method that uses both ion irradiation and vapor deposition is a non-equilibrium process, and by performing ion irradiation during film formation on the substrate surface, accelerated ions and neutral particles collide with the alumina thin film surface. So-called atomic pinning, which hits surface atoms.
mg) phenomenon, and are themselves captured as impurities in the thin film. As a result, many vacancies and interstitial atoms are generated inside the crystals of the thin film, causing volumetric expansion of the alumina thin film and generating compressive stress. In this case, rotating the substrate to homogenize the thin film as in the conventional method promotes the migration of surface atoms, reduces lattice defects, and ultimately acts in the direction of relieving compressive stress.

For this reason, we stopped the rotation of the substrate during film formation, and
Furthermore, by regulating the acceleration energy and film-forming temperature, compressive stress can be effectively applied to the inside of the thin film.

It is also presumed that the improvement in smoothness is related to the increase in density due to the increase in compressive stress.

[Embodiment] Hereinafter, an embodiment of the present invention will be described in detail with reference to FIG.

FIG. 1 is a schematic diagram showing a film forming apparatus used in this example. 1 in the figure is a vacuum container, and a vacuum pump 2 is connected to this container 1 for creating a predetermined degree of vacuum inside the container 1. An electron beam heating evaporator 3 for vapor deposition is provided within the vacuum vessel 1 . A target 5 on which a deposit is sputtered by an Ar ion beam from an ion source 4 provided in the container 1 is arranged in the container. A substrate holder 6 equipped with a heating mechanism is arranged inside the vacuum container 1 . In the vacuum container 1, an introduction pipe 7 is provided for supplying gas to the vicinity of the substrate held by the substrate holder 6. Further, an ion source 8 is provided in the vacuum vessel 1 for irradiating the vicinity of the substrate held by the substrate holder 6 with ions. Furthermore, numeral 9 in the figure is an ion source for irradiating ions at a high acceleration voltage. The ion source 9 is connected to the vacuum vessel 1 via a mass separation magnet 10, an acceleration tube 11, and an operating vacuum pump 12.

Example 1.2 and Comparative Examples 1 to 7 First, after holding the titanium substrate 13 in the substrate holder 6 placed in the vacuum container 1 of the film forming apparatus described above, the vacuum pump 2 is activated to pump the inside of the vacuum container 1. For example LX 1O-6to
It was exhausted to about rr. Subsequently, aluminum (Aρ) is evaporated from the electron beam heating evaporator 3 at a rate of 2 people/see, and at the same time oxygen ions are accelerated from the oxygen ion source 8 at an energy of 15 to 401<eV and a current density of 340
An) substrate 13 during deposition under the conditions of μA/cm2
Alumina (A!1203) with a thickness of 2 μm by irradiating the surface
A thin film was formed. Note that when rotating the substrate, the rotation speed was 2 rpm, and the substrate temperature was 140°C and 220°C.

The hardness of the alumina thin films formed in Example 1.2 and Comparative Examples 1 to 7 was measured, and the surface properties were observed using a transmission electron microscope using a replica method. The results are shown in Table 1 below.

Examples 3 to 5 and Comparative Examples 8 to 18 First, after holding a substrate 13 made of glass (trade name: Corning 7059, manufactured by Corning Glass Co., Ltd.) in the substrate holder 6 placed in the vacuum container 1 of the film forming apparatus described above. , operate the vacuum pump 2 to move the inside of the vacuum container 1 to, for example, LX 10.
The exhaust was pumped to about "" torr. Next, the target 5 was set to AΩ, and an Ar ion beam was irradiated from the ion source 4 to sputter 8ρ under the condition of 2 people/see.

At the same time, oxygen gas is supplied from the gas introduction pipe 7 at a rate of 1.4X.
The ion source 9 is supplied with a partial pressure of 10-'torr.
Accelerate monovalent or quadrivalent ions of Ar with energy 120 to 800 keV and current density 3 to 10 μA/cm2.
The surface of the substrate 13 was irradiated under these conditions to form a 2 μm thick alumina (Aρ20.) thin film. When rotating the substrate, the rotation speed is 2 rpm, and the substrate temperature is
The temperatures were 160°C, 230°C, and 300°C.

The hardness of the alumina thin films formed in Examples 3 to 5 and Comparative Examples 8 to 13 was measured, and
The surface texture was observed using a transmission electron microscope using a replica method. The results are shown in Table 2 below.

As is clear from Tables 1 and 2 above, Examples 1 to 5
Stop the board as shown, and increase the acceleration energy to 20k.
It can be seen that by setting the film-forming temperature to 200° C. or higher, an alumina thin film having a hardness of 2HOHv or higher and excellent surface smoothness can be formed.

[Effects of the Invention] As detailed above, according to the present invention, the internal compressive stress is improved, a hard and smooth alumina thin film can be formed, and it can be effectively used for coating various structural parts, etc., and has other remarkable effects. play.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a film forming apparatus used in an example of the present invention. 1... Vacuum container, 3... Electron beam evaporator, 4, 9
．． 8... Ion source, 5... Target, 6... Substrate holder, 7... Gas introduction tube, 13... Substrate. Applicant's representative Patent attorney Takehiko Suzue Procedural Amendment Heisei Home, 10. J21 Japan Patent Office Commissioner Wataru Fukasawa 1, Indication of the case Patent Application No. 2-215801 2, Title of the invention Method for forming a hard alumina thin film 3, Person making the amendment Relationship with the case Patent applicant Limes Co., Ltd. 4, Agent: Suzuei Naikoku Patent Office, 3-7-2 Kasumigaseki, Chiyoda-ku, Tokyo Address: 100 Telephone: 03 (3502) 3181 (Main representative) Description 7, Contents of amendment (1) Contents of amendment, page 3, line 4, middle box of the description In the second section, the phrase ``It concerns the formation method.'' is corrected to ``It concerns the formation method.'' (2) In box 4, line 16 of the specification, "surface atoms" is corrected to "atom."

Claims (1)

[Claims] When forming a hard alumina thin film on the surface of a substrate in a vacuum container using both ion irradiation and vapor deposition, the substrate is held still, and the ion irradiation and vapor deposition are performed at an acceleration energy of 20 keV or higher and a film formation temperature of 200° C. or higher. A method for forming a hard alumina thin film, the method comprising: