JP2002146543A - Method and device for vacuum film-formation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device suppressing effect of abnormal discharge on the thickness of a formed film, in a vacuum film-forming method, in which plasma discharge is generated by a high voltage energy source of the processing device on the surface of a belt-like object to be formed with a film, and a thin film is vapor-deposited by flowing, on the surface of this object, a gaseous starting material for the thin film formation. SOLUTION: Depending on the presence or absence of abnormal discharge detected by an abnormal discharge detector 11, the processing conditions to be inputted in their controller 12 are switched to those under abnormal or normal time by a switching device 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for vacuum-forming a thin film such as a protective film coated on a magnetic layer of a video tape.

[0002]

2. Description of the Related Art Generally, a magnetic layer of a digital video tape is very thin and may be damaged by contact during use. Therefore, a protective film is coated on the magnetic layer.

Conventionally, a vacuum film forming method and apparatus for forming such a thin film are shown in a block diagram of a vacuum film forming apparatus shown in FIG. 2 is wound on a take-up reel 5 via a rotating drum 4, such as a base film of a digital video tape wound around 2. Magnetic layer on the surface of the
A plasma discharge is generated between a high voltage energy source of the process device 6 and the magnetic layer on the surface of the strip-shaped film-forming object 3 where the plasma discharge is generated. In the meantime, a gas composed of a carbon compound such as toluene or a catalyst, which is a material of the protective layer 7 formed on the magnetic layer on the surface of the strip-shaped film-formed object 3, is flowed, and the CVD (Chemic) is performed.
The protective layer 7 is deposited on the magnetic layer by an Al Vapor Deposition method, and the thickness of the protective layer 7 is adjusted so that the protective layer 7 deposited on the magnetic layer has an appropriate thickness. It is always measured by the measuring machine 8 and the measurement result is inputted to the computer 9, and the computer 9 determines the state of the plasma discharge so as to obtain an appropriate film thickness, the feeding speed of the band-shaped film-forming material 3, and the material of the protective layer 7 The process conditions such as the supply amount of gas to be processed are calculated, and the process device 6, the supply reel 2, the rotating drum 4, the take-up reel 5, the gas supply source, and the like are controlled by the process condition control device 10 based on the process conditions. Is what you do.

[0004]

However, according to the above-described conventional vacuum film forming method and the apparatus therefor, since a high voltage energy source is used for the process apparatus, the plasma discharge causes the magnetic layer on the surface of the band-shaped film to be formed. In addition to the normal discharge that occurs during the abnormal discharge, irregular plasma discharge occurs between the other parts and the irregular plasma discharge. The energy of a normal discharge generated between the magnetic layer on the surface of the object to be film-formed and the magnetic layer is deprived, and the energy required for film-forming is insufficient, and a sharp change appears in the generated film thickness.

[0005] Since it is not distinguished whether the change in the film thickness is due to process condition control or abnormal discharge, it is corrected based on process condition control in the same manner as in normal film formation. . However, correction based on process condition control is ineffective for abnormal discharge,
For example, if the control to increase the voltage of the high-voltage energy source of the process equipment and perform the control to strengthen the plasma discharge is performed by the correction based on the process condition control to compensate for the decrease in the film thickness due to the abnormal discharge, the plasma discharge leak may occur. This increases the abnormal discharge and promotes the abnormal discharge. The leakage of the plasma discharge is not eliminated, and the energy of the normal discharge generated between the magnetic layer on the surface of the band-shaped film-forming material, which is originally required, is deprived. The lack of energy required for the membrane will still continue.

An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a vacuum film forming method and an apparatus therefor which suppress the influence of abnormal discharge on a generated film thickness.

[0007]

In order to solve the above-mentioned problems, the present invention provides a method in which a belt-like film-forming object is caused to travel by a feed mechanism inside a vacuum chamber, and the surface of the belt-like film-forming material is A plasma discharge is generated by a high-voltage energy source of a process apparatus, and a gas as a material of a thin film to be formed on the surface of the band-shaped film on which the plasma discharge is generated is caused to flow. In the vacuum deposition method of depositing a thin film on the surface, the presence or absence of abnormal discharge by the high voltage energy source of the process equipment is detected, and when the abnormal discharge is not detected, the thickness of the thin film deposited on the surface of the belt-shaped film-forming object is determined. It is a vacuum film forming method that measures and controls the film thickness by a normal process condition based on the measured value, and when an abnormal discharge is detected, controls the film thickness by an abnormal process condition to stop the abnormal discharge. Abnormal It is capable to minimize the impact on the product thickness by electrodeposition.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, a belt-shaped film-forming object is caused to travel by a feed mechanism inside a vacuum chamber, and a surface of the band-shaped film-forming object is placed on a surface of a process apparatus. A plasma discharge is generated by a high-voltage energy source, and a gas, which is a material of a thin film to be formed on the surface of the band-shaped object on which the plasma discharge is generated, flows, and the thin film is formed on the surface of the band-shaped object. In the vacuum deposition method of vapor deposition, the presence or absence of abnormal discharge due to the high voltage energy source of the process equipment is detected, and when no abnormal discharge is detected, the thickness of the thin film deposited on the surface of the band-shaped film-forming object is measured. A vacuum film forming method that controls the film thickness by normal process conditions based on the measured values, and controls the film thickness by abnormal process conditions to stop abnormal discharge when abnormal discharge is detected,
By changing the control method between when an abnormal discharge occurs and when it does not occur, it is possible to take an appropriate action according to the state.

According to a second aspect of the present invention, in the detection of abnormal discharge, the voltage of a high-voltage energy source of a process apparatus, the change rate of the thickness of a thin film deposited on the surface of a band-shaped film-forming object, are detected. The abnormal discharge detection device detects the abnormal process condition, which is calculated based on the measurement value of the film thickness measuring machine that measures the film thickness of the thin film, based on the presence or absence of abnormal discharge detection by the abnormal discharge detection device. 2. The apparatus of the vacuum film forming method according to claim 1, further comprising a switching device for switching between an abnormal process condition to be stopped and inputting the process condition to the process condition control device, wherein the normal process condition and the abnormal process condition are changed by the switching device. By switching and inputting to the process condition control device, the thin film can be deposited under appropriate process conditions according to the state.

According to a third aspect of the present invention, there is provided the vacuum film forming method according to the first aspect, wherein the abnormal process condition is a process condition immediately before the occurrence of abnormal discharge. Due to the immediately preceding process conditions, when abnormal discharge stops and is restored, it has an effect that a stable film thickness can be generated early.

An embodiment of the present invention will be described below with reference to the drawings.

(Embodiment) FIG. 1 is a configuration diagram of a vacuum film forming apparatus during normal discharge according to an embodiment of the present invention, and FIG. 2 is a configuration of a vacuum film forming apparatus during abnormal discharge according to an embodiment of the present invention. FIG. 3 is a diagram showing a configuration diagram of a conventional vacuum film forming apparatus.
The same parts as those described above are denoted by the same reference numerals and description thereof will be omitted.

FIG. 1 differs from FIG. 3 only in that a normal plasma discharge is generated between the high-voltage energy source of the process device 6 and the magnetic layer on the surface of the band-shaped film-formed object 3. Without, whether the irregular plasma discharge leaks between other parts and abnormal discharge occurs,
Abnormal discharge detection device 11 based on data such as the voltage of the high-voltage energy source of process device 6 and the rate of change in the thickness of protective layer 7 deposited on the magnetic layer on the surface of band-shaped film formation material 3.
When the abnormal discharge detection device 11 detects that abnormal discharge has occurred, the process condition input terminal to the process condition control device 12 is switched to the abnormal process condition, and the abnormal discharge detection device 11 In the case where no abnormal discharge is detected due to the above, a switching device 13 for switching the process condition input terminal to the process condition control device 12 to the normal process condition is provided. An abnormal time computer 14 for calculating and inputting the normal process conditions and a normal time computer 15 for calculating and inputting the normal process conditions based on the measurement result of the film thickness measuring device 8 for measuring the thickness of the protective layer 7 are provided. It is a point.

In the above case, the normal process condition is determined based on the measurement result of the film thickness measuring device 8 as described above.
The normal state computer 15 calculates process conditions such as the state of plasma discharge such that the film thickness becomes an appropriate film thickness, the feed speed of the strip-shaped film-forming object 3, and the supply amount of gas used as the material of the protective layer 7. The abnormal process conditions are as follows. The high-voltage energy source of the process device 6 leaks not only between the magnetic layer on the surface of the strip-shaped film-forming object 3 but other parts. It is obtained by calculating the voltage value of the high-voltage energy source of the process device 6 by the abnormal time computer 14 so that the regular plasma discharge is eliminated.

By setting the process conditions immediately before the occurrence of abnormal discharge as the abnormal process conditions, a stable film thickness can be generated at an early stage.

The strip-shaped film-forming object 3 in the present embodiment is a magnetic tape in which a 300 nm-thick iron oxide magnetic material layer is formed on a 10 μm-thick polyethylene terephthalate-based base film. A gas consisting of a carbon compound such as toluene or a catalyst is flowed over the strip-shaped film-forming object 3 by a process device 6 by a CVD method to a thickness of 1
This is to form a protective layer 7 of crystalline carbon of about 0 nm.

The feeding mechanism for the belt-shaped film-forming object 3 uses a plurality of rollers such as a supply reel 2, a rotating drum 4, and a take-up reel 5, and a film thickness measuring device 8 for the protective layer 7 The film thickness is determined by measuring the transmittance of the tape.

As described above, according to the vacuum film forming method and the apparatus according to the present embodiment, when the abnormal discharge detecting device 11 does not detect abnormal discharge, the protective layer 7 measured by the film thickness measuring device 8 is used. Is input to the normal time computer 15 and the process conditions calculated by the normal time computer 15 are changed. For example, if the generated film thickness is larger than a predetermined value, the high voltage energy source of the process device 6 Reduce the voltage,
The normal discharge control is performed to reduce the generated film thickness by, for example, reducing the supply amount of a gas serving as a material of the protective layer 7, and the abnormal discharge detection device 11 uses the voltage of the high voltage energy source of the process device 6. If it is determined that abnormal discharge has occurred based on a phenomenon such as that the protection layer 7 is too high or the film thickness of the deposited protective layer 7 suddenly changes, the process condition control device 12 in the switching device 13 The abnormal discharge can be shortened by switching the process condition input terminal to the abnormal process condition, reducing the voltage of the high-voltage energy source of the process device 6 and stopping the leaked plasma discharge. It stops in time and returns to a normal state to obtain a predetermined generated film thickness. It corresponds to when the abnormal discharge detection device 11 detects abnormal discharge and when it does not detect abnormal discharge. By performing different types of process condition control, it is possible to determine whether the variation in the generated film thickness is based on the process condition control or abnormal discharge. As in the case where the control is performed, it is not appropriate to cope with the variation in the thickness of the formed film, and it takes time to notice the change.

In this embodiment, the band-shaped film-forming object 3 is described as a magnetic tape having a magnetic layer formed on a base film. However, it is necessary to form a thin film by vacuum film formation. If there is a certain thing, it can be applied to any belt-like film-formed object 3 and the same effect can be obtained.

[0020]

As described above, according to the vacuum film forming method and the apparatus therefor according to the present invention, the occurrence of abnormal discharge caused by the use of high-voltage energy which cannot be avoided in the film forming process can be recovered in a short time, An effect is obtained that defects in the formed film thickness due to generation can be minimized.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a vacuum film forming apparatus during normal discharge according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a vacuum film forming apparatus during abnormal discharge according to the embodiment of the present invention.

FIG. 3 is a configuration diagram of a conventional vacuum film forming apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum tank 2 Supply reel 3 Strip-shaped film-forming object 4 Rotary drum 5 Take-up reel 6 Process device 7 Protective layer 8 Film thickness measuring machine 9 Calculator 10, 12 Process condition control device 11 Abnormal discharge detection device 13 Switching device 14 When abnormal Calculator 15 Normal Calculator

Claims (3)

[Claims] 1. A belt-shaped film-forming object is run inside a vacuum chamber by a feed mechanism, and the surface of the band-shaped film-forming object is
A plasma discharge is generated by a high-voltage energy source of the process apparatus, and a gas that is a material of a thin film to be formed on the surface of the band-shaped film-forming object where the plasma discharge is generated is flown.
In a vacuum deposition method that deposits a thin film on the surface of a strip-shaped workpiece, the presence or absence of abnormal discharge due to the high voltage energy source of the process equipment is detected, and when no abnormal discharge is detected, deposition is performed on the surface of the strip-shaped workpiece. Measure the thickness of the thin film
A vacuum film forming method in which the film thickness is controlled by normal process conditions based on the measured values, and when abnormal discharge is detected, the film thickness is controlled by abnormal process conditions to stop abnormal discharge. 2. An abnormal discharge detection device, which detects an abnormal discharge based on a voltage of a high-voltage energy source of a process apparatus and a change speed of a film thickness of a thin film deposited on a surface of a band-shaped film-forming object, Depending on the presence or absence of abnormal discharge detection by the abnormal discharge detection device, the process is switched between normal process conditions calculated based on the measured values of the film thickness measuring machine that measures the thin film thickness and abnormal process conditions that stop abnormal discharge. The apparatus of the vacuum film forming method according to claim 1, further comprising a switching device for inputting to the condition control device. 3. The vacuum film forming method according to claim 1, wherein the abnormal process condition is a process condition immediately before the occurrence of abnormal discharge.