JPH05239644A - Method for continuously forming thin film on metallic thin sheet - Google Patents

Abstract

PURPOSE:To provide the method for continuously forming a thin film on a metallic thin sheet by which a good thin film in which the variation of the film quality is small. CONSTITUTION:A metallic thin sheet 12 coiled from a metallic thin sheet coil 11 is subjected to preliminary heating, and this preliminarily heated metallic thin sheet 12 is subjected to pretreatment by plasma. Next, a thin film is formed on the metallic thin sheet 12, and this metallic thin sheet 12 is coiled. These stages are continuously executed in a vacuum state, and thin films are continuously formed on the metallic thin sheet 12. In this case, the preliminary heating treatment is executed under the conditions in which the pressure of a preliminary heating chamber 2 is regulated to <=5X10<-3>Torr, and the heating temp. T( deg.C) and heating holding time (t) (min) satisfy the relationship of T+150t> 325.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for continuously forming a thin film on a metal thin plate unwound from a metal thin plate coil, and more particularly to a continuous thin film forming on a metal thin plate whose pretreatment process conditions are defined. Regarding the method.

[0002]

2. Description of the Related Art A method for continuously forming a thin film on a metal thin plate unwound from a metal thin plate coil by vacuum evaporation or ion plating in a vacuum is not yet performed on an industrial level. Not not.
However, it is considered that the thin film can be continuously formed by analogy with the experience of thin film formation by the batch system so far.

That is, in the conventional batch system, a thin metal plate is preheated, then pretreated with plasma to activate the surface, and then a thin film is formed by vapor deposition or ion plating. Therefore, it is considered that the thin film can be continuously formed by configuring the apparatus so that these steps are continuously performed.

However, according to the experiments conducted by the inventors of the present invention, it was confirmed that when the conditions of the batch system are directly applied to the continuous process, a great variation occurs in the film quality.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a continuous thin film forming method for a thin metal plate which has a small variation in film quality and can form a good thin film.

[0006]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a step of preheating a metal thin plate unwound from a metal thin plate coil, and a plasma for the preheated metal thin plate. A thin film forming method comprising a step of performing a pretreatment and a step of forming a thin film on a thin metal plate, wherein the preliminary heating step comprises:
The pressure in the preheating chamber is 5 × 10 ⁻³ Torr or less, and the heating temperature T (° C.) and the heating holding time t (minutes) are performed under the condition that the relationship of T + 150t> 325 is satisfied. A method for forming a continuous thin film on a thin metal plate is provided.

The inventors of the present application have examined the cause of the variation in film quality when continuously forming thin films on a thin metal plate, and have found that the preheating conditions have a great influence on the variation in film quality. ..

As described above, the pretreatment step is a treatment for activating the surface of the metal thin plate with plasma. By stabilizing the plasma at this time, a good quality thin film can be stably obtained. From this point of view, this step is also performed in the conventional batch system. But,
When DC glow discharge or the like is performed as a pretreatment, the formed plasma is often unstable immediately after the start.

It is considered that the cause of this phenomenon is that a large amount of gas is generated from moisture or dirt physically or chemically adsorbed on the surface of the thin metal plate. However, in the batch system, degassing from the surface of the thin metal plate is promoted by the cleaning action of the plasma and the temperature rise, so that the surface is cleaned over time and the plasma becomes stable. Therefore, a high quality thin film can be stably obtained relatively easily.

On the other hand, when the thin film is continuously formed, the thin metal plate is continuously supplied during the pretreatment, so that the thin metal plate is cleaned before the pretreatment. Otherwise, the plasma will not be stable.

Therefore, in the case of a continuous system, it is necessary to clean the metal sheet as much as possible before the pretreatment. Then, such cleaning of the thin metal plate is achieved by a preheating step performed prior to the pretreatment. It is considered that the following mechanism is capable of cleaning the surface of the thin metal plate by preheating and eventually leading to plasma stabilization in the pretreatment.

When a thin metal plate is heated in a high vacuum, water and dirt adhering to the surface can be gasified and desorbed by a so-called thermal desorption phenomenon. Therefore, by this, the surface can be cleaned.

When pretreatment is performed in plasma without performing such preheating treatment, heat is first received at that time, abrupt degassing occurs, and the impedance of plasma changes. Moreover, such a phenomenon becomes extremely unstable depending on the state of the substrate. Therefore, such a phenomenon can be prevented by preliminarily cleaning the surface of the thin metal plate by the preheating treatment, and the plasma of the pretreatment is stabilized.

In this case, the amount of degassing generally increases as the heating temperature increases or the heating time increases. Then, these conditions, that is, the processing pressure (vacuum degree), the heating temperature and the heating time must be defined in a range such that the surface of the thin metal plate has a sufficient cleanliness for stabilizing the plasma of the pretreatment.

According to the results of the study by the present inventors, the pressure in the preheating chamber is 5 × 10 ⁻³ Torr or less, and the heating temperature T
By performing the preheating treatment under the condition that (° C.) and the heating holding time t (minute) satisfy the relationship of T + 150t> 325, the degassing amount in the pretreatment is higher than that in the case where the heating treatment is not performed. It can be reduced by one digit or more, and gas emission in plasma is also reduced, which leads to stabilization of plasma.

[0016]

Embodiments of the present invention will be described below.
FIG. 1 is a schematic configuration diagram showing a continuous thin film forming apparatus for carrying out the present invention. A thin metal plate coil 11 is housed in the unwinding coil chamber 1, and a thin metal plate 12 is unwound from the coil 11. The unwound thin metal plate 12 reaches the preheating chamber 2 and is preheated under the conditions described later. Heating at this time is performed by, for example, a lamp heater, an electron gun,
A plasma gun can be used. The preheated metal thin plate 12 reaches the pretreatment chamber 3, where it is pretreated with plasma, and the surface of the metal thin plate 12 is activated by this treatment. The plasma at this time is obtained by, for example, DC glow discharge, RF self-discharge, ECR discharge, or the like. After such pretreatment, the thin metal plate 12 is removed from the deposition chamber 4
Then, a thin film is formed on the thin metal plate 12. The thin film can be formed by a general thin film forming technique such as vacuum deposition and ion plating. Then, the thin metal plate 12 is cooled in the cooling chamber 5 and wound in the winding coil chamber 6. These series of steps are continuously performed, and each processing chamber is maintained in vacuum. Further, the processing chambers are connected by a passage kept in a vacuum, and the process from unwinding to winding of the thin metal plate is performed without breaking the vacuum. The heating in the preheating chamber 2 is performed under conditions such that the pressure in the preheating chamber 2, the heating temperature T (° C.), and the heating holding time t (minutes) stabilize the pretreatment plasma.

Next, an experiment conducted to understand such a condition will be described. Here, the pressure in the preheating chamber is set to 5 × 10 ⁻³ Torr to 1 × 10 ⁻⁴ Torr, the heating temperature and the heating time are variously changed to perform the preheating, and the plasma is stabilized in the subsequent pretreatment. I understood the sex. The result is shown in FIG. FIG. 2 is a graph showing the stability of the pretreatment plasma under each preheating condition, in which the horizontal axis represents the heating holding time and the vertical axis represents the heating temperature. In the figure
Indicates that the pretreatment plasma is in a stable state, ×
Indicates that the plasma is unstable.

In FIG. 2, the region where the plasma is stable ○
The boundary line between the unstable region x and the unstable region X is the straight line A, and if it is on the upper right side of the straight line A, the plasma of the pretreatment becomes stable. When this straight line A is expressed by the relationship between the heating temperature T (° C.) and the heating holding time t (minutes), it becomes as shown in the following formula (1). T + 150 · t = 325 (1) Therefore, if the inequality shown in the following equation (2) is satisfied, the plasma will be stabilized. T + 150 · t> 325 (2) Here, the formula (2) is the following formula (3) when the heating holding time t is constant, and the following formula (3) when the heating temperature T is constant. It can be expressed by equation (4). T> -150t + 325 (3) t> (325-T) / 150 (4)

The pressure in the preheating chamber is set to 5 × 10 ^-3 Torr.
Instead of ^{~1 × 10 -4 Torr, 1 ×} 10 -4 Torr~5 × 10
Similar results were obtained with ^-6 Torr. On the contrary,
When the pressure in the preheating chamber exceeds 5 × 10 ^-3 Torr, that is, when the degree of vacuum is low, regardless of heating conditions,
The pretreatment plasma tended to be unstable. From this, it was confirmed that the pressure in the preheating chamber should be 5 × 10 ⁻³ Torr or less. From the above experiment, the pressure in the preheating chamber was 5 × 10 ⁻³ Torr or less, and the heating temperature T
If the preheating is performed under the condition that (° C.) and the heating holding time t (minutes) satisfy the relationship of T + 150t> 325, the plasma of the pretreatment can be stabilized, and eventually the quality of the formed film can be improved. It was confirmed that it would lead to stabilization.

Next, the experimental results for confirming the degassing effect in the preheating treatment will be described. Here, a mild steel material is used as the thin metal plate, and the pressure (vacuum degree) in the preheating chamber is used.
Is set to 1 × 10 ⁻⁴ Torr and heating temperature is 100 ° C. and 2
The gas release rate at 50 ° C. was determined. The result is shown in Figure 3.
Shown in. FIG. 3 is a graph showing the degassing effect in the preheating treatment, with the horizontal axis representing the heating and holding temperature and the vertical axis representing the gas release rate. From FIG. 3, it was confirmed that the degassing effect in the preheating treatment was large, and that the higher the heating temperature, the larger the effect.

[0021]

According to the present invention, there is provided a continuous thin film forming method for a thin metal plate which is capable of forming a good thin film with less variation in film quality. In particular, by defining the preheating conditions in a specific range, it is possible to stabilize the plasma in the pretreatment and thus to stabilize the film quality.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a continuous thin film forming apparatus for carrying out the present invention.

FIG. 2 is a graph showing the stability of pretreatment plasma under preheating conditions.

FIG. 3 is a graph showing the effect of degassing in preheating treatment.

[Explanation of symbols]

1; unwinding coil chamber, 2; preheating chamber, 3; pretreatment chamber,
4; vapor deposition chamber, 5; cooling chamber, 6; winding coil chamber, 11;
Coil, 12; thin metal plate.

Claims (1)

[Claims] 1. A method of preheating a thin metal plate unwound from a thin metal coil, a step of pretreating the preheated thin metal plate with plasma, and a step of forming a thin film on the thin metal plate. In the preheating step, the pressure in the preheating chamber is 5 × 10 ⁻³ Torr or less, and the heating temperature is T (° C.).
And the heating and holding time t (minutes) are carried out under the condition that the relationship of T + 150t> 325 is satisfied, a continuous thin film forming method for a metal thin plate.