JP2000297374A - Substrate and pet film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To negate the internal stress possessed by a thin film and to prevent the deformation of the substrate induced by thin film formation, i.e., the warpage generated in a flexible film-like material by forming the thin film on the substrate curved in a direction of negating the internal stress remaining in the thin film. SOLUTION: When the thin film 13 having the compressive residual internal stress is deposited on the surface of the flexible film-like substrate 3, the substrate 3 tends to warp to a crown shape with the deposited surface faced upward on account of the compressive stress. The substrate 3 is warped in an opposite direction at deposition, by which the stress by the warpage of the substrate 3 and the compressive internal stress possessed by the thin film are negated and a flat state is obtained. The residual internal stress of the thin film 13 is previously measured or the degree of curling is previously quantitatively recognized and the curvature meeting the deformation quantity by the residual internal stress of the thin film 13 is imparted to the substrate 3, by which the substrate 3 formed with the thin-film 13 is obtained. The radius of curvature at which the induction of wrinkles, flaws, etc. on the film does not occur is important.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for producing a thin film having low residual stress and excellent adhesion to a substrate.

[0002]

2. Description of the Related Art Conventionally, as a method of forming a thin film, PV has been used.
In the field D, a sputtering method, an ionization vapor deposition method and the like are known, and in the CVD field, a plasma CVD method is known as a typical example.

FIG. 1 shows a CVD apparatus using a capacitively-coupled high-frequency glow discharge, and a high-frequency power supply system (5).
, High-frequency power supply electrode (1), counter ground electrode (2), substrate (3) having a surface to be formed, flat electrodes arranged in parallel
The plasma region (4) generated between (1) and (2) is shown. This method is an apparatus for forming a film by using a self-bias acting on the substrate (3) disposed on the high-frequency power supply electrode (1) side.

FIG. 2 shows an inductively coupled CVD.
A plasma region (4) formed by applying induction energy from a high-frequency excitation coil (6),
A film-like substrate is formed by applying an electric field from an auxiliary electrode for applying an external bias to ions of the raw material activated in the plasma region.
This method leads to (3) and forms a thin film on a flexible substrate (3). In this method, a film-shaped substrate is continuously moved by a cylindrical roller and a guide roller.
(3) A thin film is continuously formed thereon.

[0005]

When a thin film having a large compressive residual stress typified by a diamond-like carbon thin film is formed using the CVD apparatus shown in FIG. 1, the diamond-like carbon thin film becomes 10 ¹⁰ dyne / cm ^2. Since the film has a large compressive stress, the film becomes a thin film in which a force acting such that the film warps in a convex manner on the film-forming surface acts.

This state will be described with reference to FIG. FIG.
(A) is a thin film with compressive residual internal stress on the substrate (3).
The state where (13) is formed is shown. When compressive residual internal stress is acting on the thin film (13), the thin film (13) tends to warp as shown in the figure. In this case, a stress is naturally generated between the substrate (3) and problems such as a decrease in adhesion between the thin film (13) and the substrate (3), and the occurrence of peeling and cracks.

In particular, when a flexible film-shaped substrate is used as the substrate, the thin film curls so that the thin film is on the outside and the substrate is on the inside.

When the CVD apparatus shown in FIG. 2 is used, the compressive residual stress in the longitudinal direction in which the substrate (3) moves is canceled out by winding the substrate, which does not cause a serious problem. The substrate also curls after film formation due to the compressive residual internal stress in the width direction of the substrate (3).

The compressive residual stress in the width direction of the substrate (3) does not easily return to its original state even if a correction process is performed later. Even if the residual stress is restored, the stress remains at the interface between the thin film and the substrate. This causes cracks, peeling, etc., and lacks reliability from a long-term viewpoint.

The above problem is a problem that thin films formed by the CVD method (gas phase reaction method) exist to some extent.

An object of the present invention is to solve the problem of residual stress of a thin film formed by a gas phase method as described above.

[0012]

Means for Solving the Problems [First invention] A first invention is a film forming apparatus for forming a thin film on a substrate by a vapor phase method, and cancels internal stress remaining in the thin film after film formation. A film forming apparatus having a function of bending a substrate in a direction is summarized.

In the first aspect of the present invention, the vapor phase method means a sputtering method, a vapor deposition method, and a CVD method. The types of thin films include diamond-like carbon thin films, semiconductor thin films,
Generally known general thin films such as an insulator thin film and a conductor thin film can be exemplified. Curving the substrate in a direction to cancel the internal stress means that the substrate is warped in a direction opposite to the direction in which the substrate itself warps due to the stress remaining inside the thin film. By doing so, when the substrate is warped due to the residual internal stress of the thin film, the warpage applied in advance and the warp of the thin film cancel each other out, and as a result, an integrated product of the thin film and the substrate without warpage can be obtained. .

The function of bending the substrate is a substrate holding means or a substrate transfer means for forcibly bending the substrate, and a means for bending the substrate by causing the substrate to follow a curved member. The present invention can be applied to all thin films having compressive residual internal stress or tensile residual internal stress.

An example of a procedure for practicing the present invention will be described below. Measure the residual internal stress of the thin film in advance, or quantitatively grasp the degree of curling by forming the thin film. -The film is formed by giving the substrate a curvature commensurate with the amount of deformation of the thin film due to residual internal stress. By performing the above steps, a substrate on which a flat thin film is formed can be obtained.

FIG. 5B schematically shows the state of a thin film obtained by utilizing the present invention. Flexible thin film substrate (3) with compressible residual internal stress (13)
When a film is formed on the surface, the substrate (3) tends to warp as shown in FIG. 5 (A) due to compressive stress. Therefore, as shown in the present invention, by warping the substrate in the direction opposite to the state shown in FIG. 5A during film formation, the stress due to the warping of the substrate and the compressive residual internal stress of the thin film are reduced. Can be canceled to realize a state as shown in FIG. 5 (B). It is important that the curvature given to the substrate in advance during film formation has a radius of curvature that does not induce wrinkles, scratches, or the like in the film.

[0017]

In the film formation, by applying in advance a substrate having a surface on which a film is to be formed to cancel the internal stress of the thin film to be formed, the internal stress of the thin film can be canceled. It is possible to prevent or reduce the deformation of the substrate caused by the action, that is, the curl phenomenon that occurs in a flexible film.

[0018]

EXAMPLES In the following examples, an example is shown in which a diamond-like carbon thin film is formed on a film-like substrate. However, the material of the substrate is not particularly limited as long as it can impart a curvature. Of course, the present invention can be applied to a thin film formed on a substrate as long as the internal stress remaining after the film formation becomes a problem. Further, in the following embodiments, an example of a thin film having a compressive residual internal stress will be described. However, when a thin film having a tensile residual internal stress is formed, the way of giving the curvature may be reversed.

[Embodiment 1] An embodiment of the present invention will be described with reference to FIGS. 3 and 4 show a roll-to-roll type capacitively coupled high-frequency plasma CVD apparatus having a parallel plate configuration. FIG. 4 is a perspective view of the apparatus as viewed three-dimensionally from an oblique direction, and FIG. 3 is a cross-sectional view of the apparatus as viewed from a direction perpendicular to the direction in which the film serving as a substrate is fed (the direction indicated by arrow (12)).

In FIGS. 3 and 4, the high-frequency power supply system (13.
56MHz) (5), flexible substrate film (3),
High frequency power supply electrode (1), counter ground electrode (2), plasma area
(4), the direction (12) in which the substrate is sent out is shown.

This device determines the film quality by controlling the self-bias acting on the high-frequency power supply electrode (1) side, and constitutes a simple system that does not require any special external bias or the like. . Of course, a configuration in which a DC bias is applied from the outside may be employed.

In this embodiment, a film serving as a substrate
As (12), thickness 10 μm, width 130 mm, length 90 m
PET (polyethylene terephthalate) was used. The high-frequency power supply electrode (1) has a width of 180 mm, a length of 250 mm, and a thickness of 20 mm. As shown in FIG. 3, the electrode (1) is given a radius of curvature of 360 mm in the width direction (the horizontal direction in FIG. 3) and is curved. The opposite ground electrode (2) also has the same dimensions as the high-frequency power supply electrode (1), and has the same 360-mm radius of curvature as the high-frequency power supply electrode in the same direction.

The thin film is formed while running the film (3) as a substrate at a speed of 50 m / min in the direction shown by the arrow (12) in FIG. During the formation of this thin film, the film (3) runs along the high-frequency power supply electrode (1), and thus curves as shown in FIG. 3 (3) according to the curvature of the high-frequency power supply electrode (1).

By doing so, the substrate is curved in the direction opposite to the direction shown in FIG. 5A in advance with respect to the thin film 13 to be formed as shown in FIG. Thin film (13)
Can be canceled out.

Using the plasma CVD apparatus having the above configuration, a diamond-like carbon thin film is
It was formed to a thickness of 0 °. The conditions for forming the diamond-like carbon thin film were 1.7 × 10 ¹⁰ when the apparatus shown in FIG. 1 was used.
The film was formed under the conditions for forming a diamond-like carbon thin film having a compressive residual internal stress of dyne / cm ² . Specific film forming conditions are shown below. Input power 1.5 Kw Deposition pressure 80 Pa Substrate spacing 15 mm Substrate temperature Unheated Deposition gas C ₂ H ₆ + H ₂ (200 sccm / 50 sccm)

When the film recovered by the winding roll was visually inspected, a flat state before the thin film was formed could be maintained, and the physical properties of the diamond-like carbon thin film were not recognized at all, and were uniform over the entire surface. Was formed. Regarding the hardness, Vickers hardness could not be measured due to the problems of the substrate and the film thickness. However, the durability when the steel ball was pressed and moved as a substitute property was satisfactory without any problem.

This is because when a diamond-like carbon thin film having a compressive stress is formed on the surface of the substrate (3) running along the curvature of the electrode (1) at the time of film formation, the diamond-like carbon thin film remains inside. It is considered that the substrate tends to warp in the direction opposite to the warpage of the substrate due to the stress, and as a result, the warps cancel each other, and a state in which almost no residual internal stress is realized.

Comparative Example 1 As Comparative Example 1, a diamond-like carbon thin film (500 mm thick) was formed using the conventionally known high-frequency plasma CVD apparatus shown in FIG. 1 under the same film forming conditions as in Example 1. An example is shown below. P as substrate
The use of an ET film and the size and shape of the electrodes are the same as in the first embodiment. That is, the difference from the first embodiment is the same as that of the first embodiment except that a curvature is given to the electrode and that the film as the substrate is curved with the same curvature according to the electrode having the curvature.

Although the diamond-like carbon thin film obtained in this comparative example did not show any peeling from the film, the film itself had a large curl state, and was made to be very flat without any correction treatment. It had a difficult shape. In addition, in the durability when the steel ball was pressed and moved, a phenomenon in which the steel ball locally peeled from the interface with the film occurred. This means that a large stress is generated between the diamond-like carbon thin film and the substrate.

[Comparative Example 2] This comparative example is an example in which the radius of curvature of the high-frequency power supply electrode (1) is 180 mm, which is the same dimension as the electrode width, under the conditions of Example 1, and the other conditions are the same. It is an example. In this comparative example, when the diamond-like carbon thin film was formed to a thickness of 500 °, the force for restoring the film having the forced curvature was too strong at the time of film formation, and the micro- Occurred, and the film was locally peeled off, and no effect of compensating for, ie, neutralizing, the stress of the thin film was obtained.

According to the results of this comparative example, in order to cancel the compressive residual internal stress existing in the diamond-like carbon thin film, if the stress given by bending the substrate in advance during the film formation is too large, the stress given to the substrate becomes It is concluded that they remain and cause problems.

[Optimal value of radius of curvature] Table 1 below
Shows a pair of substrates (1), under the conditions of Example 1.
By changing the curvature given to (2), the film (3)
It summarizes the results when a diamond-like carbon thin film is formed thereon.

[0033]

[Table 1]

From Table 1, under the film forming conditions shown in Example 1, when forming a diamond-like carbon thin film having a compressive residual internal stress of about 1.7 × 10 ¹⁰ dyne / cm ² on a PET film, PET film (thickness 10)
μm, width 130mm, length 90m) 320 ~ 400m
It is concluded that the stress remaining in the diamond-like carbon thin film can be canceled by giving a radius of curvature of about m in the state shown in FIG.

[0035]

[Embodiment 2] In this embodiment, an expander roll is added under the same conditions as in Embodiment 1 before and after the film travels between parallel plate type electrodes, which are thin film forming regions, and simultaneously, a diamond-like carbon thin film is formed at 500 °. This is an example.
The expander roll is a device that removes bending and wrinkles of the film by applying tension in the width direction of the film. As a result of the film formation in this example, by stretching the film before forming the thin film through an expander roll, minute wrinkles are completely removed, and after forming the thin film, the flatness of the thin film is further improved. It turned out that it could be done. Further, the physical properties of the diamond-like carbon thin film were almost the same as those in Example 1 described above. The use of this expander roll is an extremely effective measure when the film running system is long.

[0036]

Embodiment 3 In this embodiment, in the conventional plasma CVD apparatus shown in FIG. 1, only the film (3) as the substrate is provided with the same curvature of 360 mm as shown in FIG. In addition, the film (3) was formed by running while passing from one side of the plasma region (4) to the other in the same manner as shown in FIG.

In this embodiment, a method of forming a film by giving a predetermined curvature only to the substrate while the pair of electrodes is of a conventionally known parallel plate type configuration. In this embodiment,
It is assumed that a tape-shaped flexible substrate is used as the substrate. Then, it is configured to continuously pass between the electrode (1) and the electrode (2). At this time, the same effect as in the first embodiment can be obtained by curving the substrate so that stress acts on the substrate in the width direction (direction perpendicular to the direction in which the substrate is conveyed) by the substrate conveyance system and performing film formation. it can.

In order to carry out this embodiment, a transport mechanism for giving a curvature to the film (3) is required, but it is characterized in that a conventional parallel plate type electrode can be used. The state of the diamond-like carbon thin film obtained in this example is the same as that obtained in Example 1, and no peeling, cracking, warping, etc. of the film as the substrate were observed. Was preferred.

[0039]

Embodiment 4 This embodiment is different from the conventional inductively coupled plasma CVD apparatus shown in FIG. 2 in that the surface of the cylindrical can roller (8) is made concave while the surface of the guide roller is made convex. The film is formed by giving a constant radius of curvature in the width direction of the film (3) at the portion where the diamond-like carbon thin film is formed. By adopting the configuration of the present embodiment, the compressive residual internal stress of the diamond-like carbon thin film can be canceled, and a thin film having no flattening or cracking can be obtained. If tensile residual stress exists in the thin film,
Contrary to the above construction, the internal stress of the thin film can be canceled by making the surface of the cylindrical can roller (8) convex while the surface of the guide roller is concave.

[0040]

According to the present invention, a thin film is formed by giving a curvature to a flexible substrate in advance in a direction in which a residual stress of the film to be formed is generated to cancel the residual stress of the film to be formed. Stress applied by the formation can be alleviated and further neutralized, that is, the interface stress can be controlled so as to be infinitely zero, and the film can be made flat after the thin film is formed. As a result, it is possible to secure the adhesion at the interface while maintaining the physical properties of the thin film.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an internal structure of a conventionally used parallel plate type capacitively coupled high frequency plasma CVD apparatus.

FIG. 2 is a schematic diagram of a conventionally used inductively coupled high frequency plasma CVD apparatus.

FIG. 3 is a sectional view showing an internal structure near an electrode of the diamond-like carbon thin film forming apparatus used in the embodiment of the present invention.

FIG. 4 is a sectional view showing an internal structure near an electrode of the diamond-like carbon thin film forming apparatus used in the embodiment of the present invention.

FIG. 5 is a simple sectional view comparing a conventional state (A) of a film after a thin film is formed with a state (B) obtained by using the present invention.

[Description of Signs] 1 High-frequency power supply electrode 2 Counter ground electrode 3 Substrate 4 Plasma region 5 High-frequency power supply system 6 High-frequency excitation coil 7 External bias application auxiliary electrode 8 Cylindrical can roller 9 DC power supply 10 Guide roller 11 Plasma quartz tube 12 Roll Of thin film 13 Thin film

Claims (10)

[Claims] 1. A substrate on which a thin film is formed by a vapor phase method, wherein the thin film is formed on the substrate curved in a direction to cancel internal stress remaining in the thin film. . 2. A substrate on which a diamond-like carbon thin film is formed by a gas phase method, wherein the diamond-like carbon thin film is formed on the substrate curved in a direction to cancel internal stress remaining in the diamond-like carbon thin film. A substrate characterized by being formed. 3. A substrate on which a thin film is formed by a CVD method, wherein the thin film is formed on the substrate curved in a direction to cancel internal stress remaining in the thin film. 4. A substrate on which a diamond-like carbon thin film is formed by a CVD method, wherein the diamond-like carbon thin film is formed on the substrate curved in a direction to cancel internal stress remaining in the diamond-like carbon thin film. A substrate characterized in that: 5. A PET film on which a thin film is formed by a vapor phase method, wherein the thin film is formed on the PET film curved in a direction to cancel internal stress remaining in the thin film. PET film. 6. A PET film on which a diamond-like carbon thin film is formed by a vapor phase method, wherein the diamond-like carbon thin film is curved in a direction to cancel internal stress remaining in the diamond-like carbon thin film. P formed above
ET film. 7. PET on which a thin film is formed by a CVD method
A PET film, wherein the thin film is formed on the PET film curved in a direction to cancel internal stress remaining in the thin film. 8. A PET film on which a diamond-like carbon thin film is formed by a CVD method, wherein the diamond-like carbon thin film is formed on the PET film curved in a direction to cancel internal stress remaining in the diamond-like carbon thin film. Formed in the shape of P
ET film. 9. The substrate according to claim 1, wherein the gas phase method is a sputtering method or a vapor deposition method. 10. The PET film according to claim 5, wherein the vapor phase method is a sputtering method or a vapor deposition method.