KR100671422B1 - Forming method of Aluminum coatings by sputtering - Google Patents

Abstract

The present invention relates to a method for forming an aluminum film by sputtering,

Forming an aluminum film on the substrate by sputtering, but evaporating aluminum from the aluminum target attached to the sputtering evaporation source under an inert gas atmosphere to form an aluminum layer on the substrate; Forming an aluminum oxide layer on the aluminum layer by reactive sputtering by sputtering aluminum and simultaneously injecting oxygen gas; Repeating the above steps to form a film in the form of a multilayer film in which the aluminum layer and the aluminum oxide layer alternately form a layer.

Sputtering, Aluminum Film

Description

Forming method of Aluminum coatings by sputtering

1 is a schematic configuration diagram of a film forming apparatus for forming an aluminum film according to an embodiment of the present invention,

2 is a schematic view illustrating a coating layer showing an aluminum film formed by an embodiment of the present invention;

Figure 3 is a photograph showing a coating layer formed by an embodiment of the present invention.

<Description of Symbols for Main Parts of Drawings>

1: vacuum chamber 2: sputtering evaporation source

3: aluminum target 4: substrate

5: Substrate holder 6: Substrate heating device

7a, 7b: Shutter 8: Substrate Rotator

9: Substrate Bias Supply 10: Thickness Meter

11: gas inlet 12: vacuum gauge

21: base material 22: aluminum layer

23: aluminum oxide layer M: a film in the form of a multilayer film

The present invention relates to a method for forming an aluminum film by sputtering, and more particularly, to a method of forming an aluminum film used to improve corrosion resistance of various materials, provide a beautiful appearance, and improve durability by increasing the hardness of a coating layer. The present invention relates to a method for forming an aluminum film by coating aluminum and aluminum oxide in a multi-layer by controlling the structure of the film and at the same time increasing the hardness to improve scratch resistance.

Aluminum is beautiful in color and has excellent corrosion resistance and heat resistance, so it is widely used for decorative films such as cosmetic cases and accessories, as well as conductive films for semiconductors, protective films for magnetic materials and steel sheets, home appliances in thermal systems, and automotive mufflers. have.

In addition, aluminum has a low density, excellent workability, reflectivity, and thermal conductivity due to metal properties, and thus has a wide variety of industrial applications.

Recently, as the aerospace industry is greatly developed, researches to improve the corrosion resistance and mechanical properties by coating aluminum on various materials have been actively conducted.

For example, various materials used in airplanes are coated with aluminum to produce materials having improved corrosion resistance and wear resistance, or aluminum is vacuum deposited on steel sheets to be used as materials for various containers and home appliances. Is diverse.

On the other hand, aluminum is most commonly used physical vapor deposition because the efficiency is low when the coating is electroplated due to low efficiency. Physical vapor deposition includes vacuum deposition, sputtering and ion plating. In order to improve corrosion resistance, ion plating is generally used.

However, aluminum coatings generally contain many pores in the coating layer and also have disadvantages of poor adhesion to the substrate. In order to solve this problem, in order to solve the vacuum deposition, the substrate must be heated to a high temperature and ion plated. In order to increase the voltage applied to the substrate or to increase the ionization rate it is necessary to introduce a larger amount of discharge gas.

However, when the substrate is heated to a high temperature, not only may the damage be caused to the substrate, but also the adhesion amount decreases as the substrate becomes a high temperature, thereby reducing economic efficiency, and a method of applying a high voltage to the substrate may also damage the substrate. .

In addition, when the amount of discharge gas is increased to increase the ionization rate, the discharge gas is mixed into the film to damage the film, and scattering occurs between the discharge gas and the evaporated aluminum, which also causes a decrease in adhesion amount.

In order to solve these problems, various methods of vacuum deposition, sputtering, ion plating apparatus or method have been proposed, and these techniques mainly include uniformity of film and adhesion between film and substrate, stability of generated plasma, and evaporation source. Material and structure, high ionization rate, etc. are proposed.

On the other hand, sputtering is a process of applying a high voltage to a target in an inert gas atmosphere to generate plasma discharge, and then inert gas ions present in the discharge collide with the target to remove the target material and form a film on the substrate.

In such a sputtering process, when various reaction gases are injected during sputtering, compounds such as oxides can be easily formed.

In this regard, a method of improving coating properties such as corrosion resistance using metals and oxides has been proposed through Japanese Patent Application Laid-Open No. 5-15043. However, when coating oxides alone, poor adhesion or damage to the coating itself may occur. There was a limit that problems such as can be caused.

The present invention has been made in view of the above problems, and is designed to control the growth structure of the aluminum film having the characteristic of growing into columnar tissue and at the same time to realize high corrosion resistance, and initially to form an aluminum film of a predetermined thickness. The purpose of the present invention is to provide a method for forming an aluminum film by sputtering, in which aluminum and aluminum oxide are formed in multiple layers thereon, thereby greatly improving hardness and corrosion resistance.

The present invention for achieving the above object, forming an aluminum film on the substrate by sputtering, evaporating aluminum from the aluminum target attached to the sputtering evaporation source in an inert gas atmosphere to form an aluminum layer on the substrate; Forming an aluminum oxide layer on the aluminum layer by reactive sputtering by sputtering aluminum and simultaneously injecting oxygen gas; Repeating the above steps to form a film in the form of a multilayer film in which the aluminum layer and the aluminum oxide layer alternately form a layer.

More preferably, the thickness of the aluminum layer which forms the said film is 0.5-2 micrometers, and the thickness of an aluminum oxide layer is 0.1-0.5 micrometer.

More preferably, the film in the form of a multilayer film is characterized in that the number of layers is formed of five or more layers.

More preferably, the present invention is characterized by using a non-balanced magnetron as the sputtering evaporation source.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

1 is a schematic configuration diagram of a film forming apparatus for forming an aluminum film according to an embodiment of the present invention.

The sputtering of this embodiment takes place in a conventional sputtering apparatus equipped with a sputtering evaporation source, an example of such apparatus is shown in FIG.

In the vacuum chamber 1, a sputtering evaporation source 2, an aluminum target 3 and a substrate 4 are installed, and the substrate holder 5, the substrate heating apparatus 6, the shutters 7a and 7b, the thickness monitor ( 10), a gas inlet 11 for injecting gas and a vacuum gauge 12 for measuring the degree of vacuum are provided.

As the sputtering evaporation source 2, it is preferable that a non-equilibrium magnetron system is used. The non-equilibrium magnetron method increases the ionization rate of the substrate by applying a separate magnetic field to the outside of the magnetron sputtering evaporation source, and improves the characteristics of the film. An electromagnet (not shown) is used as a means for maintaining the non-equilibrium. .

When the non-equilibrium magnetron method is used as the sputtering evaporation source 2, since the reactivity of aluminum and oxygen is excellent in forming the aluminum oxide layer as described below, there is an advantage in that aluminum oxide having a well-defined stoichiometry can be manufactured. .

The substrate 4 should be pretreated before and after being loaded into the container. For example, ultrasonic cleaning is used as a pretreatment method before loading into the container.

Contaminants typically present in components such as fixtures, tools, and bearings include lubricating oils, cutting oils, oxides and fingerprints, which are removed by pretreatment.

Such a pretreatment method of the substrate 4 may be appropriately applied depending on the characteristics of the substrate 4 to be processed, the contaminants to be removed, and the like. For example, in the laboratory, ultrasonic cleaning using a cleaning agent or a solvent after light polishing is appropriate, and industrially, sandblasting or chemical cleaning is used.

Mount the pretreated substrate 4 to the substrate holder 5, fix the aluminum target 3 to the sputtering evaporation source 2, close the container and evacuate to the required degree of vacuum using a vacuum pump (not shown). .

When the vacuum degree is 10 ⁻⁶ Torr or less, an inert gas (argon gas in this embodiment) is injected to clean the substrate 4, and a negative voltage is applied to the substrate 4 to clean the substrate 4.

The cleaning of the substrate 4 includes a process of removing not only impurities such as organic matter present in the substrate 4, but also naturally occurring oxide films. If these impurities are not removed sufficiently, it will affect the adhesion and should be sufficiently cleaned.

The substrate 4 is cleaned by inducing a glow discharge by applying a negative voltage of 400 to 1000 V to the substrate 4 in an argon gas atmosphere of about 10 ⁻² Torr. In this way, argon ions present in the discharge region collide with the substrate 4 to remove impurities present in the substrate 4. In this case, it is preferable to use a pulse power source as a power source applied to the substrate in order to prevent damage to the substrate by the arc.

After the substrate 4 is cleaned, the target 3 is cleaned in the next step.

The cleaning of the target 3 is to remove impurities present on the surface of the target 3 and is performed immediately before the sputtering process. To this end, the target 3 is cleaned by sputtering for about 3 minutes after generating a plasma by applying power to the sputtering evaporation source 2.

When the target 3 is cleaned, the shutter 7a attached to the substrate side and the shutter 7b attached to the evaporation source side are simultaneously opened to form aluminum and aluminum oxide in multiple layers.

First, aluminum is deposited on the substrate 4 to a predetermined thickness, and then aluminum oxide is deposited, and the process of depositing aluminum again thereon is repeated.

In the deposition of aluminum oxide, a so-called reactive sputtering method formed by sputtering aluminum while simultaneously injecting argon gas and oxygen gas through the gas inlet 11 is used.

When the aluminum oxide film is formed to a predetermined thickness, the injection of oxygen gas is stopped again, and only the argon gas is injected to deposit aluminum to a predetermined thickness, and this process is repeated several times to form a multilayer coating layer. 2 is a schematic view showing a coating layer showing an aluminum film formed through this process.

The thickness of the aluminum oxide layer is appropriately about 0.1 ~ 0.5㎛, when the thickness of the aluminum oxide layer is too thin does not show the effect of tissue control and increase the strength of the coating, if too thick, the coating easily breaks the cause of poor adhesion Because it becomes.

The thickness of the aluminum layer is suitably about 0.5 to 2㎛, because when the thickness of the aluminum layer is too thin, the effect of improving the corrosion resistance by aluminum is insignificant, and when too thick, the hardness of the film is reduced.

The number of layers of the multilayer film is preferably composed of at least five layers, because when the thickness is smaller than five layers, the effect of increasing the hardness and corrosion resistance by the coating layer is insignificant.

When the aluminum and aluminum oxide are formed in multiple layers under the above conditions, it is possible to control the growth structure of the aluminum film, which is characterized by the growth of columnar tissue, so that pores are generated in the coating layer. It can be prevented to improve the coating effect of the coating layer.

<Example>

The invention is an example of manufacturing an aluminum film on a cold rolled steel sheet having a width of 10 cm and a thickness of 1 mmT, and initially depositing 2 μm of aluminum and then alternately depositing aluminum and aluminum oxide thereon.

The substrate 4 was ultrasonically cleaned for 10 minutes using acetone and alcohol before charging to the vacuum container 1. Next, the aluminum target 3 was installed, the board | substrate 4 was mounted, the vacuum chamber 1 was closed, and it exhausted using the vacuum pump.

When the degree of vacuum reaches 10 ⁻⁶ Torr or less, 1.2 × 10 ⁻² Torr of argon gas is injected through the gas inlet 11 to clean the substrate 4, thereby performing secondary cleaning of the substrate 4 by glow discharge. Was carried out. At this time, the voltage applied to the board | substrate 4 was 700V, and the electric current was 200-400 mA, and it cleaned for 30 minutes.

When cleaning of the substrate 4 is completed and the vacuum degree is again 10 ⁻⁶ Torr or lower, inject argon gas to be 3 × 10 ⁻³ Torr and apply a 300 V power source to the sputtering evaporation source 2 to generate plasma for 3 minutes. The target 3 was cleaned.

Next, shutters 7a and 7b were opened and aluminum was deposited on the substrate 4 to a thickness of 2 占 퐉.

Next, aluminum oxide and aluminum were formed in multiple layers, and aluminum oxide was first deposited and aluminum was deposited thereon.

As the aluminum oxide, a so-called reactive sputtering method formed by sputtering aluminum while simultaneously injecting argon and oxygen gas through the gas inlet 11 was used. In this way, aluminum oxide was first deposited for 30 minutes to form aluminum oxide having a thickness of about 0.3 m.

After the aluminum oxide film production was completed, oxygen gas injection was stopped again, and only argon gas was injected to deposit aluminum to a thickness of 1 μm. This process was repeated 10 times to form a multilayer coating layer.

3 is a photograph taken by enlarging a magnification of 3000 times using a scanning electron microscope, and it can be seen that a multilayer film is well formed.

On the substrate 4 coated by the method of this example, a salt spray test and a pressure resistance test were performed, and hardness thereof was measured.

The salt spray test was performed up to 24 cycles with 1 cycle of spraying for 5 hours in 5% NaCl solution and 16 hours rest. Pressurized moisture test was conducted continuously at the time of peeling of the film with one cycle to control the humidity to 100% at 125 ℃, 2 atm for 13 hours.

In the salt spray test, the aluminum film of the same thickness generated red blue in about 300 hours, while the invention according to the present invention maintained about 500 hours. In the pressure and humidity test, the blue film of the same thickness produced red blue in two to three cycles, while the invention according to the present invention had a slight rust in five cycles.

The hardness of the coating layer was measured by using a micro Vickers hardness tester. The load was 50 g and the hardness of the uncoated magnet was also measured for comparison.

In the case of the general aluminum film, the average was about 60, while in the case of the invention according to the present invention, the hardness was about 100.

The present invention described above can be embodied in many different forms without departing from the spirit or main features thereof. Therefore, the above embodiments are merely examples in all respects and should not be construed as limiting.

According to the method of the present invention, it is possible to manufacture a high-density coating by controlling the structure of the coating, and to improve the corrosion resistance and the hardness of the various materials, as well as to significantly increase the hardness of the product characteristics and lifetime You will get the effect.

Claims (4)

Sputtering to form an aluminum film on the substrate, Evaporating aluminum from an aluminum target attached to the sputtering evaporation source under an inert gas atmosphere to form an aluminum layer on the substrate; Forming an aluminum oxide layer on the aluminum layer by reactive sputtering by sputtering aluminum and simultaneously injecting oxygen gas; Repeating the above steps to form a film in the form of a multi-layer film consisting of alternating layers of aluminum and aluminum oxide layer; sputtering aluminum film forming method comprising a. The method of claim 1, The thickness of the aluminum layer which forms the said film is 0.5-2 micrometers, The thickness of an aluminum oxide layer is 0.1-0.5 micrometer, The aluminum film formation method by sputtering characterized by the above-mentioned. The method of claim 2, The multi-layered film is formed by sputtering the aluminum film, characterized in that the number of layers is formed in five or more layers. The method according to any one of claims 1 to 3, A non-equilibrium magnetron is used as said sputtering evaporation source, The aluminum film formation method by sputtering.

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