KR950004780B1 - Method for making an aluminum evaporating boat - Google Patents

Abstract

The method increases the life of aluminum evaporating boat by coating boron nitride on the evaporating spots in the boat made of amorphous carbon or graphite. The method comprises (A) making an evaporating boat (10) of amorphous carbon with density of 1.4 g/cm3 or graphite; and (B) spreading the liquid powder of boron nitride with thickness of 0.01 mm on the evaporating spots (11) and drying.

Description

Manufacturing method of aluminum evaporation boat

1 is a perspective view showing an example of an aluminum evaporating boat manufactured according to the present invention.

* Explanation of symbols for main parts of the drawings

10: evaporation boat 11: evaporation site

20: boron nitride coating layer

The present invention relates to a method for manufacturing an aluminum evaporation boat for evaporating aluminum, and more particularly, to a method for producing an aluminum evaporation boat coated with boron nitride on an evaporation boat of amorphous carbon or graphite material.

For evaporation of a material by resistance heating (direct current flow), refractory metals such as tungsten, molybdenum and tantalum, and materials such as amorphous carbon, graphite or TiB ₂ BN are used in the form of coils, boats or crucibles.

By using these, metals having a low melting point can be evaporated relatively easily and a film having high purity can be formed. Among them, aluminum coating is beautiful in color and color change due to corrosion in air is better than other metals, so it is very widely used for decorative coatings such as cosmetic cases and accessories, as well as conductive films of semiconductors, protective films of magnetic materials and steel sheets. It is used. Aluminum also has a wide variety of industrial applications due to its inherent properties (low density, good processability, corrosion resistance and thermal conductivity). Recently, as the space development and the aviation industry are greatly developed, researches to improve the corrosion resistance and mechanical properties by coating aluminum on various materials have been actively conducted. McDonnell Douglas, for example, uses aluminum as a coating for various parts used in airplanes as a corrosion and wear resistant material. On the other hand, in Germany, aluminum is vacuum-deposited on steel sheets and used in containers and home appliances. However, aluminum is one of the most difficult materials to evaporate because of its low melting point and high vaporization temperature and reaction with most refractory metals. Therefore, until now, TiB ₂ BN boats with little reaction with aluminum have been used (Japanese Patent Laid-Open No. 56-156761), or a temporary evaporation method using tungsten wire has been used. However, TiB2 BN boats are expensive (approximately 50-100 times that of tungsten or graphite boats) and basically evaporate while the front of the boat is wet, resulting in a loss of evaporation material and a significant evaporation rate depending on the amount of evaporation. There are disadvantages such as change. In the case of using tungsten wire, there are many problems such as short lifespan of up to 2-3 cycles, difficulty in controlling evaporation rate, and maximum deposition thickness of several thousand kPa.

When amorphous carbon or graphite bow is used as the evaporation source, when the temperature becomes about 800 ° C. or more, carbides of Al ₄ C ₃ are formed and the bottle is damaged and cannot be used. Japanese Patent Application Laid-Open No. 58-77572 proposes a method of separating evaporative crucibles and heating parts by using an electrical insulator to solve these problems, but this is basically limited to the evaporation rate due to the temperature difference between the heating part and the evaporation part. This has the disadvantage that the heating source is complicated.

The present invention has been proposed in order to solve the above problems, by using amorphous carbon or graphite as a boat material and coating boron nitride on the evaporation site so that the evaporation source and the evaporation material do not come into contact with each other so that the incorporation of impurities is small during evaporation of aluminum. To provide a method for economically manufacturing aluminum evaporating boats with a long life span, an object thereof is provided.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated.

The present invention is formed of amorphous carbon or graphite having a density of 1.4 g / cm ³ or more as a conventional evaporation boat, and then formed a boron nitride coating layer of 0.1 mm or more on the evaporation site of the evaporation boat to form aluminum. It relates to a method of manufacturing a boat for evaporation.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

First, amorphous carbon or graphite having a density of 1.4 g / cm ³ or more is used as a material, and is processed into a conventional evaporating boat 10 shape as shown in FIG.

Next, a boron nitride coating (coating) having a thickness of 0.01 mm or more is evenly dispersed by uniformly dispersing boron nitride in a powdered state to a thickness of 0.01 mm or more on the evaporation portion 11 of the processed evaporation boat 10. A layer is formed on the evaporation site. At this time, the coating treatment of boron nitride is preferably carried out by directly injecting powdered boron nitride onto the boat.

It is preferable to limit the density of the amorphous carbon or graphite to 1.4 g / cm ³ or more. The reason is that when the density is low, a large amount of impurities are included and pores are present in the boat so that the evaporation is not constant. This is because it exhibits inferior characteristics.

In addition, the coating thickness of the boron nitride is preferably limited to 0.01mm or more, because when the coating thickness of boron nitride is 0.01mm or less, the lifetime of the evaporation source is shortened due to insufficient protection of amorphous carbon or graphite. .

At the time of evaporation of aluminum, the evaporation boat prepared as described above is placed in an evaporator, the aluminum is put therein, and the aluminum is evaporated to below 10 ^-4 Torr. In the early stage of evaporation, many gases are produced due to impurities released from boron nitride, aluminum, and boats, and thus, it is necessary to sufficiently degas the gas. After the degassing, the power is increased to melt aluminum. First, it is necessary to evaporate once or twice to form a stable film in which aluminum and boron nitride react.

After this step, there is a step in which aluminum can be deposited in earnest. At this time, aluminum no longer reacts with amorphous carbon or graphite, and evaporates smoothly in the molten state.

Hereinafter, the present invention will be described in more detail with reference to Examples.

EXAMPLE

The evaporation boat was manufactured using the material shown in Table 1 below, and the boron nitride was coated with the coating thickness as shown in Table 1 on the evaporation site of the evaporation boat and dried to produce an evaporation boat.

Each of the evaporation boats prepared as follows was placed in a vapor deposition machine, and then aluminum was charged into the evaporation boat to evaporate aluminum, thereby depositing aluminum on the steel sheet with a thickness as shown in Table 1 below. The appearance and the degree of impurity incorporation were observed, and the results are shown in Table 1 below.

In the following Table 1, the evaporation state is determined by observing the inside of the evaporation source through a sight glass. The evaporation state is divided into a wet state in which aluminum is evaporated in a molten state and aluminum is evaporated by spreading on the front of the evaporation source. It was observed visually afterwards, and the degree of impurity incorporation was expressed in comparison with the aluminum film deposited by evaporation with TiB ₂ BN boat using Auger electron spectroscopic analysis.

TABLE 1

As shown in Table 1, in the case of Inventive Example (1-4) according to the present invention, it can be seen that aluminum evaporates in a molten state and exhibits pure metallic color without coating or impurities.

On the other hand, when amorphous carbon or graphite is used as the evaporation source, and the evaporation is performed by coating boron nitride with 0.005 mm on each, [Comparative Example (1-2)], the boron nitride is coated too thinly, and aluminum is evaporated in a wet state. In the case of a non-evaporation source [Comparative Example (3)] it can be seen that the boat is damaged and not suitable for use as an evaporation source.

As described above, the present invention has the effect that the inexpensive amorphous carbon or graphite can be easily used for long-term evaporation of various aluminum coatings containing no impurities in industrial applications.

Claims (2)

Forming an amorphous carbon or graphite having a density of 1.4 g / cm ³ or more as a conventional evaporation boat, and then forming a boron nitride coating layer of 0.01 mm or more on the evaporation portion of the evaporation boat. Method for producing a boat for evaporating aluminum. The method for producing an aluminum evaporating boat according to claim 1, wherein the boron nitride coating layer is formed by directly injecting boron nitride in a powdered liquid state onto the evaporation portion of the evaporating boat.