JPS60174863A - Surface treatment of aluminum substrate for forming thin film - Google Patents

Abstract

PURPOSE:To form a favorable thin film free from surface defects by dry-etching the surface of an Al substrate to remove an oxide hydrate film and to make the surface clean and dry and by heating the Al substrate in an atmosphere contg. oxygen while preventing contact with the air contg. moisture. CONSTITUTION:The surface of an Al substrate is dry-etched by discharge cleaning, reactive gas etching, plasma etching, reactive ion beam etching or other method to remove an oxide hydrate film and to make the surface clean and dry. The Al substrate is then heated in an atmosphere contg. oxygen while preventing contact with the air contg. moisture. An oxide film is formed on the surface of the Al substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for surface treatment of an aluminum base material for forming a thin film.

Products manufactured by forming a thin film on the surface of an aluminum base material using the PVD method or CVD method include solar cells (deposition material: amorphous Si), electrophotographic photoreceptors (deposition material: Se or its alloy, amorphous 3i, etc.),
There are polygon mirrors (deposited material: A/, 3i 02 ), etc.

Such a thin film must have uniform texture and excellent adhesion to the substrate. However, in the manufacturing process of these products, various surface defects such as swelling, cracks, and pinholes may occur on the surface of the WIJ film during the formation of the vapor-deposited thin film, which poses a major problem in terms of product quality. Ta. This point will be explained in more detail below regarding the electrophotographic photoreceptor. In copying machines using electrophotographic technology, laser beam printers, etc., Se, Se-Te, Se-T is applied to the surface of the aluminum base material.
Se alloys such as e-As and 5e-As, semiconductors such as amorphous 81, amorphous metals, Zn 01C
dS, organic semiconductors, and other vapor-deposited substances are deposited using the PVD method or CV
Electrophotographic photoreceptors are manufactured by forming a photosensitive layer consisting of a thin film by vapor deposition using the D method, etc., but during the manufacturing process of this photoreceptor, swelling, cracks, and pins may occur on the surface of the photosensitive layer during formation of the photosensitive layer. There is a problem in that surface defects such as holes occur, which adversely affect electrophotographic images. The cause of such 1illI defects is that the aluminum base material is exposed to 200 to
Contaminants such as gas released from the surface of the base material when heated to 300℃ and processing oil that adheres to the surface of the base material when extruding, rolling, pressing, and cutting aluminum base materials are It is thought that this has a large influence. In order to prevent the above-mentioned defects from occurring in Will, first, reduce the gas released from the surface of the aluminum base material and remove contaminants on the surface of the aluminum base material before forming the thin film. This is very important.

As a result of extensive research on this point, the present inventors have come to believe that the state of the film on the surface of the aluminum base material before forming the thin film has a large effect.

As is well known, aluminum is a metal that is very easily oxidized, and when it comes into contact with oxygen, an oxide film is formed on the surface. Furthermore, when aluminum is placed in an environment containing moisture such as water or moisture, a hydrated oxide film is formed on its surface. The higher the temperature of the hydrated oxide production reaction, the more remarkable the growth of the hydrated oxide film, and in high-temperature environments, a hydrated oxide film of boehmite (pseudo-boehmite) or vialite is formed on the aluminum surface. The film quality of such a hydrated oxide film is extremely phased and porous compared to an aluminum oxide film formed in an environment without moisture, and its pore morphology is also complicated. In addition, the film thickness is also thick. -By the way, a hydrated oxide film is generated on the surface of aluminum material formed by ordinary extrusion processing due to contact with the moisture-containing atmosphere (oxygen) during molding, and this hydrated oxide film is Exposure to high temperatures accelerates the formation reaction of a hydrated oxide film, resulting in a thick film. The film quality of this hydrated oxide film is porous as described above, and since it is a thick film, a large amount of water is adsorbed to the film. Furthermore, because the film lacks firmness, gases such as moisture, hydrocarbons, carbon dioxide, and carbon monoxide present in the atmosphere are adsorbed to the film even after molding. In addition, contaminants such as processing oil are also adsorbed to the film as described above. Moreover, since these hydrated oxide films are as described above, they are occluded in the film. As a result, it becomes difficult to remove these particles, and even if vacuuming is performed, they cannot be easily removed. Therefore, this seems to be the cause of defects in the thin film formed on the surface of the aluminum base material.

In addition, in order to increase the mechanical strength of the aluminum material after forming, quenching treatment such as water cooling and air cooling after high temperature heating, and heat treatment are performed. As the film grows further, substances that have already been adsorbed and which cause defects on the surface of the thin film become incorporated into the film.

Moreover, rolling oil, which is a contaminant, is attached to the surface of an aluminum base material formed by rolling, and a porous hydrated oxide film is formed during rolling and annealing. Furthermore, processing oil, which is a contaminant, is also attached to the aluminum base material formed by press working, and a hydrated oxide film is formed.

The present invention has been made in view of the above-mentioned circumstances, and it is an object of the present invention to provide a method for surface treatment of an aluminum base material for forming a thin film, which can form a suitable thin film free of the above-mentioned surface defects.

The method of surface treatment of an aluminum base material for forming a thin film according to the present invention involves dry etching the surface of the aluminum base material to make it a clean, dry surface from which a hydrated oxide film has been removed, and then removing water from the aluminum base material. It is characterized by forming an oxide film on the surface of the aluminum base material by heating in an oxygen-containing gas atmosphere that does not come into contact with the atmosphere.

In the above, typical examples of aluminum base materials include base materials that support the photosensitive layer of electrophotographic photoreceptors, but there are also base materials that support vapor-deposited thin films such as solar cells, polygon mirrors, and semiconductor devices. . They are formed by extrusion molding, rolling, press molding, cutting, etc.

In the above, specific examples of dry etching include discharge cleaning, reactive gas etching, plasma etching,
Examples include reactive ion etching, reactive ion beam etching, ion beam etching, and reactive laser beam etching. When using dry etching to make the surface of an aluminum base material clean and dry with the hydrated oxide film removed, it is necessary to wash away processing oil and remove the hydrated oxide film using acid or alkaline cleaning. ,・Does not require a drying process after washing.

In the above, after the surface of the aluminum base material is made into a clean and dry surface from which the hydrated oxide film has been removed, the aluminum base material is heated in an oxygen-containing gas atmosphere that does not come into contact with the moisture-containing atmosphere. The following three methods can be used to form an oxide film on the surface.

Part 1 is oxygen 0.5-30vol 1%, especially 1-10v
This is a method of heating in a mixed gas atmosphere containing 0/% and the remainder consisting of an inert gas or a gas inert to aluminum. Argon and helium are common inert gases. Nitrogen gas is generally used as a gas inert to aluminum.

The second method is heating in an inert gas atmosphere or a nitrogen gas atmosphere. Commercially available inert gas and nitrogen gas or industrially obtained inert gas and nitrogen gas contain trace amounts of oxygen.

The third method is heating in a vacuum atmosphere. Even a vacuum atmosphere contains trace amounts of oxygen.

In these three methods, the heating temperature is 120 to 500℃.
In particular, the heating time should be 200-300℃ and 0.1-24℃.
The time is preferably 0.5 to 6 hours. 200 above
The heat treatment at ~300° C. can also serve as aging treatment in the case of an aluminum alloy for heat treatment, and can also serve as stabilization treatment in the case of an aluminum alloy for non-heat treatment. Incidentally, if the heating temperature is less than 120°C, the formation of the oxide film will not be successful, and if it exceeds 500°C, a part of the amorphous film will crystallize and become mixed, which may prevent the formation of a honeyed film.

In any of the three methods described above, the surface of the aluminum base material is prevented from coming into contact with the atmosphere containing moisture, so that no hydrated oxide film is formed on the surface. In these methods, a thin oxide film is formed on the active aluminum surface. In the first method, the thickness of the oxide film is 2
A film with a thickness of about 0 to 60 can be obtained, and in the second method, the film thickness is thinner than this. Note that in the third method, it is difficult to control the dew point, so the first and second methods are preferable.

In this way, a thin film is formed on the surface of the aluminum base material which has been surface-treated by the method of the present invention by a conventional method such as a PVD method or a CVD method.

The vapor deposited substance, that is, the substance constituting the thin film, is 3e or 5e-T, elSe -Te - for electrophotographic photoreceptors.
Se alloys such as As, 3e-As, amorphous 81
Semiconductors such as amorphous metals, ZnO, CdS
, organic semiconductors, etc., and for solar cells, A/, 5iCh, etc. for amorphous Si1 polygon mirrors.

The method of surface treatment of an aluminum base material for forming a thin film according to the present invention is to perform dry etching on the surface of the aluminum base material to make it a clean and dry surface from which a hydrated oxide film has been removed, and then remove moisture from the aluminum base material. Since it is heated in an oxygen-containing gas atmosphere that does not come into contact with the atmosphere containing oxygen and forms an oxide film on the surface of the aluminum base material, problematic hydration oxidation does not occur on the surface of the aluminum base material. Instead, a honey oxide film is formed, so gases and pollutants are absorbed and occluded significantly less than a hydrated oxide film, and even if they are adsorbed or occluded, they can be easily removed by degassing. Can be removed. Therefore, the amount of contaminants is reduced, and the amount of gas released to the surface during vacuum deposition is also very small, which prevents defects in the formed thin film and prevents the formation of defects compared to conventional methods. Thus, the troublesome work to prevent surface defects from occurring can be omitted or reduced. In addition, since a honey oxide film is formed on the surface of the aluminum base material, even if it comes into contact with the atmosphere in subsequent processes, it prevents the adsorption of substances that would cause defects on the surface of the thin film, and the hydrated oxide film The generation of can be suppressed.

Next, embodiments of the invention will be described.

After casting the molten metal of A3003 alloy, the outer diameter of the molten metal is 90I.
It was extruded into a pipe shape with a wall thickness of 8IIllIl.

The obtained extruded product was subjected to drawing processing and surface cutting to obtain an outer diameter of 8Qmm, a wall thickness of 5IllI111, and a length of 300I.
A drum-shaped aluminum]J of III11 was obtained. This drum-shaped base material was subjected to discharge cleaning (glow discharge) using argon gas to make the surface of the base material a clean and dry surface from which the hydrated oxide film was removed.

Thereafter, it was heated at 270° C. for 4 hours in a mixed gas atmosphere consisting of 20 vO 1% oxygen and the balance argon.

A honey oxide film with a thickness of approximately 40 mm was formed on the surface of this drum-shaped base material.

Next, a Se alloy was vacuum deposited on the surface of the drum-shaped aluminum base material to form a thin film, that is, a photosensitive layer. When the surface of the photosensitive layer of the obtained photoreceptor for electrophotography was observed using an optical microscope and SEM, no surface defects such as swelling, cracks, or pinholes were observed, and a flat and extremely good photosensitive layer was formed. It was confirmed that M1

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Claims (1)

[Claims] After performing dry etching on the surface of the aluminum base material to make it a clean and dry surface from which the hydrated oxide film has been removed, the aluminum base material is heated in an oxygen-containing gas atmosphere that does not come into contact with the moisture-containing atmosphere. A method for surface treatment of an aluminum base material for forming a thin film, the method comprising: forming an oxide film on the surface of the aluminum base material.