JPS59113176A - Vacuum deposition method - Google Patents

Abstract

PURPOSE:To remove surely dust on a substrate by setting the substrate in a bell jar, evacuating the jar, and cleaning the surface of the substrate. CONSTITUTION:An Al drum (substrate) 3 is supported pivotally in a bell jar, and the rotation of the drum 3 is started. The jar is shut and evacuated. Cleaning brushes 6 in the jar stay at positions A away from the drum 3 until the inside of the jar attains to a prescribed degree of vacuum. When the inside of the jar attains to about 10<-6> Torr degree of vacuum, the brushes 6 are moved to positions B where they contact with the drum 3, and the brushes 6 are rotated to clean the drum 3. After finishing the cleaning, the rotation of the brushes 6 is stopped, and the brushes 6 are returned to the positions A. The drum 3 is then heated with electron beam guns 5, and an evaporating source 7 is heated to carry out vacuum deposition on the drum 3. It is required to exchange the brushes 6 each time a vacuum deposition stage is finished.

Description

TECHNICAL FIELD This invention relates to a vacuum evaporation method in which a substrate is set in a vacuum pelger, the pressure inside the vacuum pelger is reduced, and a thin film is formed on the surface of the substrate by vacuum evaporation.

Prior Art For example, the photoreceptor drum of an electrophotographic copying machine is manufactured by forming a thin film of the photoreceptor on an aluminum drum in a vacuum pelger using a vacuum deposition method. One of the technical challenges in this field is to remove contamination of the substrate due to dust.

If the substrate on which vacuum deposition is performed is contaminated by adhesion of dust, localized abnormal growth such as pinhole-like defects and protrusions will occur in the deposited film, resulting in defective products.

To prevent this, conventional methods have been adopted.

(b) Clean the substrate before setting it in the vacuum pelger.

(b) Cleaning near the vacuum pelger.

(c) Prevention of bumping of the vapor deposited material from the evaporation source.

However, in a series of vacuum deposition steps, the most likely to contaminate the substrate is the evacuation (depressurization) process in the vacuum pelger.

Dust of 1 μm or less is always floating in gas near atmospheric pressure, and no matter how clean the air around the vacuum equipment is, the dust generated during the vacuum process remains inside the vacuum Pelger. It is raining down on
This dust becomes turbulent inside the Pel jar when the Pel jar is evacuated, and therefore, even if the substrate is cleaned before being set in the Pel jar, it is not possible to prevent the substrate from becoming contaminated.

OBJECTS The present invention aims to eliminate the above-mentioned drawbacks regarding dust removal of conventional vacuum evaporation methods, and to provide a vacuum evaporation method that can reliably remove dust stains from the surface of a substrate.

Configuration The present invention will be described in detail below along with embodiments shown in the drawings.

Now, when the degree of vacuum of the gas exceeds a certain level (i.e.,
(When the absolute national power becomes lower than a certain value), the drag of objects such as dust in the gas decreases in proportion to the density of the gas, making them easier to fall due to the action of gravity, and the mean free path (range) decreases. It can be expected that the density of suspended dust will decrease significantly.

This has also been confirmed by experiments.

This invention focuses on this fact, and by evacuating the inside of the vacuum pelger and cleaning the substrate surface to remove dust when the degree of vacuum reaches a certain level and the density of floating dust has decreased. Second, it is further characterized by preventing dust from falling and preventing removed dust from climbing up, thereby keeping the surface of the substrate clean during vacuum evaporation.

As mentioned above, since cleaning of the substrate surface according to the present invention is carried out in a vacuum pelger at a vacuum level above a certain level, it is difficult to introduce general liquid cleaning as a cleaning means. Further, blowing air is impossible because the m-force inside the Pel jar increases, and cleaning by air suction is also impossible in a vacuum. Furthermore, removing dust by electrostatic force also causes great damage to the device, making it impractical, and since it depends on the electrostatic characteristics of the dust, no reliable effect can be expected.

Therefore, in the vacuum deposition method of the present invention, the dust on the surface of the substrate is mechanically swept off with a cleaning member. As the above-mentioned cleaning member, for example, a flexible fur brush made of chemical fiber or animal hair such as rabbit hair is suitable.

Examples will be described below.

Example vapor deposition material: Amorphous 5e-As alloy (A835.5
Weight %) Substrate Nialuminum drum (diameter 80 mm x length 340 mm) Substrate temperature: 200°C Substrate heating method: Electron beam heating (during vapor deposition) Vacuum degree: ~10 TOrr.

Drum rotation speed: 20 rpm Cleaning member: Cylindrical fur brush O Operation procedure (1) As shown in FIG. to set it and start rotating.

(2) The cleaning brush 6 is provided so that it can come into contact with and separate from the aluminum drum 6 as soon as the Pel Jar is closed and exhaustion (depressurization) is started. The prisoner is stopped at a position separated from the aluminum drum 3.

(3) When the vacuum level inside the Pelger reaches 10 Torr, the cleaning brush 6 moves to the position (B) where it contacts the aluminum drum.

(4) Rotate the cleaning brush 6 to clean the rotating aluminum drum 3.

(5) When cleaning is completed, stop the rotation of cleaning brush B and return it to the original position (A).

(6) The rotating aluminum drum 6 is heated by the electron beam gun (EBG) 5.

(7) The evaporation source 7 is heated to evaporate the evaporation material and the evaporation material is evaporated onto the aluminum drum drum 3 to form a thin film of the evaporation material.

Note that the cleaning brush 6 needs to be replaced every (twice) every vapor deposition.

O Cleaning Effect FIG. 6 shows the relationship between the density of protrusions (local abnormal growth) on the vapor deposited film formed on the aluminum drum 3 by the above method and the cleaning time. Note that the protrusion density was measured using pressure-sensitive paper (Fuji Photo Film Prescale).

The cause of the protrusion generation is the substrate (
In addition to dust contamination (aluminum), outgassing from the aluminum substrate, bumping from the evaporation source 7, etc., cleaning did not completely eliminate protrusions, but a significant reduction effect was observed.

Effects As described above, according to the vacuum evaporation method of the present invention, local abnormal growth (pinholes, protrusions) caused by substrate contamination during the thin film formation process by vacuum evaporation can be significantly reduced.

7- The present invention can also be applied to the vacuum deposition method of various products in which a thin film is formed on the surface of the electrophotographic copying machine photoreceptor drum shown in the example by vacuum deposition, and similar methods can be applied. Effects can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a side view showing a state in which a substrate is set inside a Pel jar of an embodiment of a device for carrying out the method of the present invention, and Fig. 2 is a cross section showing the arrangement of equipment inside the Pel jar of the device of the embodiment. 3 are curve diagrams showing the effects of the present invention, which were produced based on the measured values by the above-mentioned apparatus. 3... Aluminum drum (substrate) 6... Cleaning brush (cleaning member) 8
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Claims (2)

[Claims] (1) In a vacuum evaporation method in which a substrate is set in a vacuum pelger, the pressure inside the vacuum pelger is reduced, and a thin film is formed on the surface of the substrate by vacuum evaporation, the substrate is set in the vacuum pelger, and the vacuum pelger is A vacuum evaporation method characterized in that after reducing the pressure inside the vacuum pelger, dust on the surface of the substrate is swept off using two cleaning members provided in the vacuum pelger, and then vacuum evaporation is performed. (2) The vacuum deposition method according to claim 1, wherein the cleaning member is a cleaning brush with flexible bristles.