JP2020125515A - Thin film deposition method and film deposition base material - Google Patents

Abstract

To provide a thin film deposition method capable of preventing an out gas from a base material from reducing a performance of a functional film, and a film deposition base material.SOLUTION: A thin film deposition method capable of forming a functional film on a base material 2 by a vacuum film deposition method comprises: a first buffer layer formation step of forming a first buffer layer 81 on a surface of the base material 2; and a first functional layer formation step of forming a first functional layer 91 having a density higher than that of the first buffer layer 81 on the surface of the first buffer layer 81. In at least a part of the first buffer layer formation step, the first buffer layer 81 is formed at a deposition temperature equal to or more than that in the first functional layer formation step.SELECTED DRAWING: Figure 3

Description

The present invention relates to a thin film forming method for forming a functional film having a predetermined function on a strip-shaped substrate using a vacuum film forming method, and a film forming substrate having a functional film having a predetermined function formed thereon. It is about.

In recent years, a method of improving the function of a product by coating the surface of a product such as a plastic film with a thin functional film has been used in other fields. An example is a barrier film in which a barrier film is formed on a plastic film for the purpose of preventing oxidation, preventing intrusion of water, etc. Other transparent conductive films, antireflection films, etc. can also be formed on the substrate.

Such a film-forming substrate is formed, for example, by a thin film forming apparatus as shown in Patent Document 1 below. In this thin film forming apparatus, a functional film is formed on a base material by a plasma CVD method which is a kind of vacuum film forming method. Specifically, the raw material gas of the functional film supplied into the vacuum chamber is decomposed by plasma, and the decomposed raw material gas is deposited on the base material to form the functional film.

JP 2001-303249 A

However, in the thin film forming method using the above thin film forming apparatus, the performance of the functional film formed on the base material may be deteriorated. Specifically, since the base material is heated by the plasma in the step of forming the functional film, outgas may be generated from the base material, and this outgas is mixed into the functional film being formed on the base material. As a result, the performance of the functional film may be deteriorated.

The present invention has been made in view of the above problems, and an object thereof is to provide a thin film forming method and a film-forming substrate capable of preventing outgas from the substrate from reducing the performance of a functional film. I am trying.

In order to solve the above problems, a thin film forming method of the present invention is a thin film forming method of forming a functional film on a base material by a vacuum film forming method, and a first buffer layer forming method for forming a first buffer layer on the surface of the base material. A first functional layer forming step of forming a first functional layer having a density higher than that of the first buffer layer on a surface of the first buffer layer; In the buffer layer forming step, the first buffer layer is formed at least at a portion at a film forming temperature equal to or higher than the film forming temperature in the first functional layer forming step.

According to the above-mentioned thin film forming method, in the first buffer layer forming step, the first buffer layer is formed at least at a film forming temperature higher than the film forming temperature in the first functional layer forming step. Since the outgas is actively generated from the base material during the formation of the first buffer layer at the film formation temperature higher than the film formation temperature in the first functional layer formation step, the first functional layer formation step is started. At that time, a state in which the outgas is exhausted from the base material can be formed, and as a result, it is possible to prevent the outgas from the base material from reducing the performance of the first functional layer.

A second buffer layer forming step of forming a second buffer layer having a density lower than that of the first functional layer on the surface of the first functional layer using the same material as that of the first buffer layer. Further, it is preferable that the film forming temperature in the second buffer layer forming step is lower than the film forming temperature in the first functional layer forming step.

By doing so, it is possible to form the film-forming substrate in which the buffer layers and the functional layers are alternately laminated while minimizing the damage to the film-forming substrate by heat.

Further, in the first buffer layer step, the film forming temperature at least at the stage when the formation of the first buffer layer is completed may be lower than the film forming temperature in the first functional layer forming step.

By doing so, it is possible to further prevent the function of the first functional layer from being reduced.

The base material is preferably made of resin.

Since a large amount of outgas may be generated from such a substrate, the thin film forming method of the present invention can be preferably used.

Further, the first buffer layer and the second buffer layer may contain hydrogen and carbon.

In such a case, there is a large difference in composition between the first buffer layer and the second buffer layer.

In order to solve the above-mentioned problems, a film-forming substrate of the present invention is formed on a substrate, a first buffer layer which is a thin film formed on the surface of the substrate, and a surface of the first buffer layer. A first functional layer which is a thin film having a higher density than that of the first buffer layer, and a thin film which is made of the same material as the first buffer layer and is formed on the surface of the first functional layer. And a second buffer layer, wherein the first buffer layer and the second buffer layer contain hydrogen and carbon, and the hydrogen concentration of the first buffer layer is the above-mentioned. The hydrogen concentration of the second buffer layer is lower than that of the second buffer layer, and the carbon concentration of the first buffer layer is higher than that of the second buffer layer.

According to the film-forming substrate, it is highly possible that outgas from the substrate is exhausted during the formation of the first buffer layer, and it is possible to prevent the function of the first functional layer from being reduced.

The hydrogen concentration of the first buffer layer is 30 at% or more and 45 at% or less, the hydrogen concentration of the second buffer layer is 45 at% or more and 60 at% or less, and the carbon of the first buffer layer is The concentration is preferably 25 at% or more and 40 at% or less, and the carbon concentration of the second buffer layer is preferably 15 at% or more and 25 at% or less.

In such a case, the function of the first functional layer can be prevented from being reduced, and at the same time, the buffer layer and the functional layer are alternately laminated while the damage to the film-forming substrate by heat is minimized. A film-forming substrate is formed.

According to the thin film forming method and the film-forming substrate of the present invention, it is possible to prevent the outgas from the substrate from reducing the performance of the functional film.

It is a schematic diagram showing the thin film forming device for performing the thin film forming method in one embodiment of the present invention. It is a schematic diagram showing the film formation substrate in one embodiment of the present invention. It is a flow chart showing Example 1 of the thin film forming method of the present invention. It is a flowchart showing Example 2 of the thin film forming method of this invention. It is a flowchart showing Example 3 of the thin film forming method of this invention. It is a graph which shows the composition of the 1st buffer layer and the 2nd buffer layer in the film-forming base material of this invention. It is the schematic showing the film-forming base material in other embodiment of this invention.

Embodiments according to the present invention will be described with reference to the drawings.

FIG. 1 is a schematic view and a front view of a thin film forming apparatus 1 according to an embodiment of the present invention.

The thin film forming apparatus 1 is for performing a surface treatment on a base material to form a thin film, and for example, forms a barrier film for the purpose of preventing oxidation and moisture invasion on a flexible plastic film. However, it is used as a protective film for foods, flexible solar cells, and the like. Specifically, in the case of a flexible solar cell, a solar cell formed by each electrode layer, a photoelectric conversion layer, and the like is formed on a strip-shaped substrate such as a plastic film, and then the solar cell is formed by the thin film forming apparatus 1. A plurality of thin films are formed on the cell to form a barrier film. As a result, infiltration of water into the solar battery cells is effectively prevented, and a flexible solar battery having excellent oxidation durability characteristics can be formed.

The thin film forming apparatus 1 is provided with an unwinding roll 3 that sends out the substrate 2, a winding roll 4 that winds up the supplied substrate 2, and a main roll arranged between the unwinding roll 3 and the winding roll 4. It has a roll 5, a main roll chamber 6 that accommodates the main roll 5, and a film forming chamber 7 that forms a thin film, and the substrate 2 sent from the unwinding roll 3 has an outer peripheral surface 51 of the main roll 5. A thin film is formed on the base material 2 by passing through each film forming chamber 7 while being conveyed along with the film, and is wound by the winding roll 4.

The unwinding roll 3 and the winding roll 4 have a substantially cylindrical core portion 31 and a core portion 41, respectively, and the base material 2 is wound around the core portion 31 and the core portion 41. By rotating the core portion 41, the base material 2 can be sent out or wound up. That is, so-called roll-to-roll conveyance is performed by the unwinding roll 3 and the winding roll 4, and the rotation of the core portion 31 and the core portion 41 is controlled by a controller (not shown), so that the feeding speed or the winding speed of the base material 2 is increased. The take-up speed can be increased and decreased. Specifically, the base material 2 is sent to the downstream side by rotating the core portion 31 on the upstream side in a state where the base material 2 receives a tensile force from the core portion 41 on the downstream side, and the core portion is appropriately fed. By applying a brake to 31, the base material 2 is sent out at a constant speed without bending. Further, by adjusting the rotation of the core portion 41, it is possible to prevent the fed base material 2 from being bent and, on the contrary, to wind the base material 2 without applying excessive tension. Has become.

Here, the base material 2 is a thin plate-shaped elongated body extending in one direction, and an elongated body having a flat plate shape with a thickness of 0.01 mm to 0.2 mm and a width of 5 mm to 1600 mm is applied. The material is not particularly limited, but a resin film such as PET (polyethylene terephthalate) is preferably used.

In this way, the unwinding roll 3 and the winding up roll 4 are paired, one of them sends out the base material 2, and the other takes up the base material 2 at the same winding speed as the above-mentioned sending speed. It is possible to convey the base material 2 while maintaining the tension applied to 2 at a predetermined value.

Moreover, the conveyance direction of the base material 2 is reversed by reversing the rotation directions of the core part 31 and the core part 41. When the transport direction is reversed from the transport direction indicated by the arrow in FIG. 1 (the direction in which the main roll 5 rotates counterclockwise to transport the substrate 2), the core portion 41 becomes the unwinding side, which is the opposite of the above. The part 31 is the winding side. Then, the film formation is performed while the transport direction of the substrate 2 is reversed every predetermined time, so that the film formation is performed while the substrate 2 reciprocates in the thin film forming apparatus 1.

The main roll 5 is arranged between the unwinding roll 3 and the winding roll 4, and is formed in a substantially cylindrical shape having a larger diameter than the core portion 31 and the core portion 41. The outer peripheral surface 51 of the main roll 5 is formed by a curved surface having a constant curvature in the circumferential direction, and is driven and controlled by a control device (not shown) to rotate. The unwinding roll 3 and the winding roll 4 are controlled in rotation in accordance with the rotation operation of the main roll 5, whereby the base material 2 fed from the unwinding roll 3 is in a state in which a predetermined tension is applied. Then, it is conveyed along the outer peripheral surface 51 of the main roll 5. That is, when the unwinding roll 3 and the winding roll 4 rotate in a state where the base material 2 is along the outer peripheral surface 51 of the main roll 5 in accordance with the rotation of the main roll 5 so as to interlock with the conveyance of the base material 2. The substrate 2 is conveyed from the unwinding roll 3 to the winding roll 4 in a posture in which the entire surface of the substrate 2 faces the film forming units 7 in a stretched state.

In this way, the base material 2 is conveyed in a stretched state, and by forming the film by the film forming unit 7 while the base material 2 is being conveyed, it is possible to prevent the base material 2 from fluttering during film formation. It is possible to improve the film thickness accuracy of the thin film laminated on the substrate 2 and prevent the generation of particles due to the flapping of the substrate 2. Further, by increasing the radius of curvature of the main roll 5, film formation is performed while the base material 2 is supported in a more flat state, so that the base material 2 after film formation can be prevented from warping. At the same time, the distance between the base material 2 and the plasma electrode 72 in the film forming section 7 becomes substantially uniform, which facilitates formation of a thin film having a uniform film thickness. The transport speed of the substrate 2 during film formation reaches 40 to 50 m/min.

Further, by making the tension from the main roll 5 to the take-up roll a little higher than the tension from the unwind roll to the main roll 5, the base material 2 can be stuck even more closely on the main roll 5.

The main roll chamber 6 is a space surrounded by a cover for accommodating the main roll 5 and keeping the pressure in the chamber constant. The main roll chamber 6 has a partition part 61 in addition to a cover that forms an exterior of the thin film forming apparatus 1, and the partition part 61 allows the main roll chamber 6 and a film forming chamber 7 described later to be installed in the thin film forming apparatus 1. It is partitioned. With this partition section 61, only a part of the substrate 2 transported along the outer peripheral section 51 of the main roll 5 is exposed to the film forming chamber 7.

Further, the cover in the depth direction (Y-axis direction in FIG. 1) forming the main roll chamber 6 in the present embodiment is arranged so as to be close to the end portion in the width direction (Y-axis direction) of the base material 2, although not shown. It is provided.

Further, in the present embodiment, the vacuum pump 71 is provided only on the film forming chamber 7 side, and the main roll chamber 6 is decompressed together with the film forming chamber 7 by operating the vacuum pump 71. A vacuum pump may also be provided on the chamber 6 side.

When the main roll chamber 6 is also provided with a vacuum pump, the pressure in the main roll chamber 6 is set to prevent the particles generated in the film formation chamber 7 from rolling up outside the film formation chamber 7. It is preferable that the pressure is set to be higher than the pressure inside the chamber 7.

In the present embodiment, the unwinding roll 3 and the winding roll 4 are housed in the main roll chamber 6, but they may be provided outside the main roll chamber 6. However, by providing these in the main roll chamber 6 as in the present embodiment, it is possible to protect the base material 2 and the base material 2 (film formation base material) after film formation from being exposed to the atmosphere.

The film forming chamber 7 is a means for forming a thin film on the substrate 2 by a plasma CVD (Chemical Vapor Deposition) method which is a type of vacuum film forming method. The film forming chamber 7 includes a vacuum pump 71 for reducing the pressure inside the chamber, a plasma electrode 72 for applying a high voltage for generating plasma, and a source gas as a source of a thin film to be formed on the substrate 2 in the chamber. It has the raw material gas supply part 73 to supply. Further, in the present embodiment, the plasma forming gas that is the raw material of the plasma is also supplied from the raw material gas supply unit 73.

In the film forming chamber 7, a voltage is applied to the plasma electrode 72 in a state where the inside of the film forming chamber 7 is decompressed by the vacuum pump 71 and the plasma forming gas is supplied from the source gas supply unit 73, so that the plasma electrode 72 Plasma is generated in the vicinity of, and the film formation chamber 7 becomes a plasma atmosphere. In such a plasma atmosphere, the source gas is supplied from the source gas supply unit 73, so that the source gas is decomposed (activated) by the plasma, and the base material 2 facing the film forming chamber 7 is formed. A thin film is formed on the film formation surface of.

Further, in the present embodiment, a pressure control mechanism (not shown) for controlling the pressure in the film forming chamber 7 by depressurization is further provided, and the vacuum pump 71 is used until a predetermined pressure is reached before the source gas is supplied. The pressure inside the film forming chamber 7 is reduced. In the present embodiment, the material gas is supplied after the pressure inside the film forming unit 7 is reduced to 10 ⁻² Pa or less. Then, the film formation is performed under the condition that the inside of the film formation unit 7 is about 0.5 Pa to 3.0 Pa by supplying the source gas.

Further, in the present embodiment, four film forming chambers 7 (film forming chambers 7a to 7d) are provided so as to be opposed to the main roll 5, and the unwinding roll 3, the winding roll 4, and the main roll 5 are provided. The film forming chamber 7a, the film forming chamber 7b, the film forming chamber 7c, the film forming chamber 7c The formation of the thin film by 7d is carried out in sequence. When the role of the unwinding roll and the role of the winding roll are changed, and the transport direction of the substrate is reversed, the substrate 2 has the film forming chamber 7d, the film forming chamber 7c, the film forming chamber 7b, and the film forming chamber 7a. The formation of the thin film is sequentially performed. Although the four film forming chambers 7 each have the vacuum pump 71, the plasma electrode 72, and the raw material gas supply unit 73, the vacuum pump 71 and the plasma included in the film forming chamber 7b in FIG. Only the electrodes 72 and the raw material gas supply unit 73 are denoted by reference numerals.

The plasma electrode 72 has a substantially U-shape that extends in the width direction (Y-axis direction) of the main roll 5, and in FIG. 1, only the cross section of the substantially U-shaped plasma electrode 72 that is substantially linear is shown. It is shown. A high frequency power source (not shown) is connected to the end of the plasma electrode 72.

Further, the folded portion of the plasma electrode 72 is formed so as to be located outside the film forming chamber 7, and only the substantially linear portion of the plasma electrode 72 faces the base material 2 on the main roll 5. ing.

Further, the plasma electrode 72 is surrounded by an electrode cover 74 having an opening in a direction facing the main roll 5. Although the film forming chamber 7 is in a depressurized state during film formation, the electrode cover 74 suppresses the diffusion of the plasma forming gas supplied in the vicinity of the plasma electrode 72, and facilitates the formation and maintenance of plasma. There is.

The raw material gas supply unit 73 is a pipe-shaped member provided in the vicinity of the main roll 5 in the film forming chamber 7 and extending in the width direction (Y-axis direction) of the main roll 5, and outside the thin film forming apparatus 1. It is connected to a source gas supply means (not shown) via a pipe. Further, the source gas supply unit 73 is provided with a plurality of openings in the Y-axis direction, and the width direction of the base material 2 (Y-axis direction) is close to the vicinity of the film forming surface of the base material 2 on the main roll 5. ), the raw material gas is supplied substantially uniformly.

Further, in the present embodiment, the source gas supply unit 73 is also connected to a plasma forming gas supply unit (not shown) outside the thin film forming apparatus 1 via a pipe, and the plasma forming gas also supplies the source gas supply unit 73 as described above. Is supplied to the vicinity of the plasma electrode 72 in the film forming chamber 7.

Here, in this embodiment, the source gas is, for example, HMDS (hexamethyldisilazane) gas. The HMDS gas contains silicon and carbon, and by supplying argon gas, nitrogen gas or the like as a plasma forming gas, a silicon carbide (SiC)-based thin film having high adhesion is formed, and as a plasma forming gas. By supplying the oxygen gas, a dense SiO 2 film having a high barrier property is formed.

Next, the thin film forming method of the present invention performed using the thin film forming apparatus 1 having the above configuration will be described.

First, FIG. 2 shows an image of a film-forming substrate in one embodiment of the present invention.

In this embodiment, a functional film called a barrier film is formed on the base material 2 by alternately stacking a silicon carbide-based thin film and a SiO 2 film on the base material 2 to form a film-forming base material.

In this embodiment, the SiO 2 film has a high barrier property as described above, and is a film that greatly contributes to the barrier property of the barrier film.

On the other hand, the silicon carbide-based thin film has a lower density than the SiO2 film and thus has a lower barrier property than the SiO2 film and does not substantially contribute to the barrier property of the barrier film. There is no limit. Instead, the adhesiveness is high as described above, and by forming this silicon carbide thin film between the base material 2 and the SiO2 film and between the SiO2 film and the SiO2 film, not only the barrier property is high but also the flexibility is high. A barrier film having high property is formed.

Here, in the present description, a layer that is involved in the function of the functional film, such as a SiO 2 film, is a functional layer, and a layer that has a lower density than the functional layer and that enhances the adhesion force of the entire functional film, such as a silicon carbide thin film. It is called a buffer layer.

First, a buffer layer is formed on the base material 2, and a functional layer, a buffer layer, and a functional layer are laminated in this order on the buffer layer. In this description, as shown in FIG. 2, the buffer layer directly formed on the base material 2 is the first buffer layer 81, and the functional layer formed on the first buffer layer 81 is the first functional layer 91. , A buffer layer formed on the first functional layer 91 is a second buffer layer 82, a functional layer formed on the second buffer layer 82 is a second functional layer 92, a second functional layer The buffer layer formed on 92 is referred to as a third buffer layer 83, and the functional layer formed on the third buffer layer 83 is referred to as a third functional layer 93. Although FIG. 2 shows an example in which the buffer layer and the functional layer are laminated by three layers, the number of layers is not limited to three layers, and may be one layer or four or more layers. Absent.

Here, the SiO2 film, which is the functional layer, can be formed into a high-purity SiO2 film by decomposing it by giving as high energy as possible to the raw material gas, so that the film formation temperature is relatively high (specifically, 60%). The film is formed at a temperature of from 120 to 120°C. The film forming temperature in the present invention is defined as the temperature of the base material 2 heated during vacuum film forming. The film forming temperature can be adjusted by, for example, the power applied to the plasma electrode, the transfer speed of the substrate 2, the temperature of the main roll 5, and the like.

On the other hand, some of the buffer layer compositions have a negative effect on the transparency of the film, such as yellowing when the film is formed at a high temperature. Therefore, basically, the film formation temperature is relatively low (specifically, , 0°C to 50°C). Therefore, basically, the film forming temperature when forming the buffer layer is lower than the film forming temperature when forming the functional layer.

FIG. 3 is a flow chart showing Example 1 of the thin film forming method of the present invention. Here, it is assumed that the buffer layer and the functional layer are formed by three layers as shown in FIG.

First, the first buffer layer 81 is formed on the base material 2 (step S1). The process of forming the first buffer layer 81 is referred to as a first buffer layer forming process in this description.

Next, the first functional layer 91 is formed on the first buffer layer 81 (step S2). The film forming temperature for forming the functional layer is referred to as a film forming temperature T0. Further, the step of forming the first functional layer 91 is referred to as a first functional layer forming step in this description.

Next, the second buffer layer 82 is formed on the first functional layer 91 (step S3). The step of forming the second buffer layer 82 is referred to as a second buffer layer forming step in this description.

Next, the second functional layer 92 is formed on the second buffer layer 82 (step S4).

Next, the third buffer layer 83 is formed on the second functional layer 92 (step S5).

Finally, the third functional layer 93 is formed on the third buffer layer 83 (step S6), and the formation of the barrier film on the base material 2 is completed.

Here, in the present invention, the film formation temperature at the time of forming the buffer layer formed after forming the first functional layer 91, that is, the second buffer layer 82 and the third buffer layer 83 is the functional layer formation temperature. Although the film forming temperature (film forming temperature T1) is lower than the film temperature (film forming temperature T0), the buffer layer formed before forming the first functional layer 91, that is, the first buffer layer. The film forming temperature of 81 is at least partially set to a film forming temperature T2 which is equal to or higher than the film forming temperature T0. In the first embodiment, the entire first buffer layer 81 is formed under the condition of the film forming temperature T2.

The reason why the first buffer layer 81 is formed at least at a part of the first buffer layer forming step at a film forming temperature which is equal to or higher than the film forming temperature in the first functional layer forming step will be described below.

The base material 2 may generate outgas when heated. For example, when the base material 2 contains water and the like, when the base material 2 is heated during film formation, the water content evaporates and is generated as outgas on the surface of the base material 2.

When this outgas is mixed into the functional film, the purity of the functional film is reduced, and the function required of the functional film may be reduced.

Here, when the first buffer layer forming step is performed from the beginning to the end at a film forming temperature lower than the film forming temperature in the first functional layer forming step, the base material 2 is formed in the first functional layer forming step. When heated further than the film formation temperature reached in the first buffer layer forming step, outgas may be newly generated from the base material 2 and the purity of the first functional layer 91 may decrease.

On the other hand, in this embodiment, the film formation temperature T2 in the first buffer layer forming step is set to be equal to or higher than the film forming temperature T0 in the first functional layer forming step, so that in the first buffer layer forming step. Outgas can be exhausted from the base material 2, and outgas can be prevented from being generated from the base material 2 in the first functional layer forming step. That is, it is possible to prevent the function of the first functional film 91 from being reduced.

In this case, outgas may be mixed into the first buffer layer 81, but since the buffer layer is a layer that hardly participates in the function of the functional film, the function of the functional film is not hindered.

Next, a flow chart showing a second embodiment of the thin film forming method of the present invention is shown in FIG.

In this embodiment, in the first buffer layer forming step, first, film formation is performed at a film forming temperature (film forming temperature T2) which is equal to or higher than the film forming temperature (film forming temperature T0) in the first functional layer forming step ( After step S1A), the film formation is performed at a film formation temperature (film formation temperature T1) lower than the film formation temperature T0 (step S1B) to form one first buffer layer 81.

As described above, in some buffer layer compositions, the transparency of the film may be adversely affected by forming the film at a high temperature. Further, the stress of the buffer layer formed at a high film forming temperature increases, and the warp of the base material 2 due to the stress of the buffer layer may increase. In such a case, unlike the present embodiment, the entire first buffer layer 81 is not formed at a high temperature, and only the minimum time necessary for exhausting outgas from the base material 2 is achieved. It is preferable to increase the film temperature, that is, to form a part of the first buffer layer 81 at a high temperature.

Here, in this embodiment, film formation is performed at a low temperature at least at the end of the first buffer layer forming step. In the case where the first buffer layer 81 having a lower film formation temperature has better adhesion to the first functional layer 91, the film formation may be performed at a low temperature at the end of the first buffer layer formation process as described above. preferable.

Next, a flow chart showing a third embodiment of the thin film forming method of the present invention is shown in FIG.

In this embodiment, in the first buffer layer forming step, film formation is first performed at a film forming temperature (film forming temperature T1) lower than the film forming temperature T0 in the first functional film forming step (step S1a). Next, film formation is performed at a film formation temperature T0 or higher (film formation temperature T2) (step S1b), and then film formation at a film formation temperature (film formation temperature T1) lower than the film formation temperature T0. By carrying out (step S1c), one first buffer layer 81 is formed.

In the case where the first buffer layer 81 having a lower film formation temperature improves the adhesion to the base material 2 and the first functional layer 91, the base material 2 may be damaged by etching or oxidation due to high temperature plasma. When there is a possibility of receiving such a film, it is preferable to form the film at a low temperature at the beginning and the end of the first buffer layer forming step.

Next, the barrier properties of the film-forming substrates obtained in Examples 1 to 3 are shown in Table 1 below. Here, as a comparative example, the barrier property of the film-forming substrate obtained by performing the first buffer layer forming step at a film forming temperature (film forming temperature T1) lower than the film forming temperature T0 in the first functional film forming step is shown. Also listed.

In each of the examples, the barrier property is greatly improved as compared with the comparative example. It is considered that this is because the outgas of the base material 2 was exhausted in the first buffer layer forming step and the purity of the first functional film 91 was improved as described above.

Next, FIG. 6 shows the composition of the first buffer layer 81 and the second buffer layer 82 in the film-forming substrate obtained by the thin film forming method of Example 1 described above. In the graph of FIG. 6, the one without hatching is a graph showing the composition of the first buffer layer 81, and the one without hatching is a graph showing the composition of the second buffer layer 82.

As shown in FIG. 6, the first buffer layer 81 and the second buffer layer 82, which have different film forming temperatures, have a large difference in the hydrogen and carbon contents, and the hydrogen concentration of the first buffer layer 81 is The hydrogen concentration is lower than that of the second buffer layer 82, and the carbon concentration of the first buffer layer 81 is higher than that of the second buffer layer 82.

As described above, the cause of the difference in the hydrogen concentration and the carbon concentration between the first buffer layer 81 and the second buffer layer 82 is that the dehydration condensation reaction is accelerated when the film is formed at a relatively high film forming temperature. It is conceivable that hydrogen is less likely to remain in the film, while carbon is more likely to remain in the film because carbonization proceeds. That is, in the first buffer layer 81 and the second buffer layer 82, the hydrogen concentration of the first buffer layer 81 is lower than the hydrogen concentration of the second buffer layer 82, and the carbon concentration of the first buffer layer 81 is When the second buffer layer 82 has a characteristic that the carbon concentration is higher than that of the second buffer layer 82, it is estimated that the film forming temperature of the first buffer layer 81 is higher than the film forming temperature of the second buffer layer 82. The outgas can be sufficiently released from the base material 2 when the buffer layer 81 is formed.

Further, the hydrogen concentration of the first buffer layer 81 is 30 at% or more and 45 at% or less, the hydrogen concentration of the second buffer layer 82 is 45 at% or more and 60 at% or less, and the carbon of the first buffer layer 81 is The concentration is preferably 25 at% or more and 40 at% or less, and the carbon concentration of the second buffer layer 82 is preferably 15 at% or more and 25 at% or less.

In such a case, the function of the first functional layer 91 can be prevented from being reduced, and at the same time, the buffer layer and the functional layer are alternately laminated while the damage to the film-forming substrate by heat is minimized. The film-forming substrate thus formed is formed.

The thin film forming method and the film-forming substrate described above can prevent outgas from the substrate from reducing the performance of the functional film.

Here, the thin film forming method and the film-forming substrate of the present invention are not limited to the illustrated form, and may have other forms within the scope of the present invention. For example, in the present description, the embodiment in which the barrier film corresponds to the functional film has been shown, but the present invention is not limited to this, and the thin film forming method of the present invention is used to form other functional films such as a transparent conductive film and an antireflection film. It may be used.

Further, although the plasma CVD method is used for forming the thin film in the present description, the present invention is not limited to this, and any vacuum film forming method in which the base material may expand due to heat may be, for example, a catalytic chemical vapor deposition method ( The thin film forming method of the present invention is preferably used even in the case of other CVD method such as Cat CVD) or other vacuum film forming method such as sputtering method and vapor deposition method.

Further, although the base material is the PET film in the above description, the base material is not limited to this and may be another resin film such as a PEN film. Further, not limited to the resin film, a metal film or the like may be used as long as it may cause outgas.

Further, in the embodiment shown in FIG. 2, the base material 2 to be film-formed is a single-layer film, but the present invention is not limited to this, and as shown in FIG. 7, the base material 2 has the coating layer 22 on the film body 21. It may be formed. The coating layer 22 is, for example, a flattening layer or an undercoat layer, which is formed by applying and drying a liquid material, and may generate more outgas than the film body 21 in a vacuum/heating environment. is there. Even in such a case, the present invention can be preferably used.

DESCRIPTION OF SYMBOLS 1 thin film forming apparatus 2 base material 3 unwinding roll 4 winding roll 5 main roll 6 main roll chamber 7 film forming chamber 7a film forming chamber 7b film forming chamber 7c film forming chamber 7d film forming chamber 21 film body 22 coating layer 31 core Part 41 Core part 51 Outer peripheral face 61 Partition part 71 Vacuum pump 72 Plasma electrode 73 Raw material gas supply part 74 Electrode cover 81 First buffer layer 82 Second buffer layer 83 Third buffer layer 91 First functional layer 92 Second 2nd functional layer 93 3rd functional layer

Claims (7)

A thin film forming method for forming a functional film on a substrate by a vacuum film forming method,
A first buffer layer forming step of forming a first buffer layer on the surface of the base material;
A first functional layer forming step of forming a first functional layer having a density higher than that of the first buffer layer on the surface of the first buffer layer;
Have
In the first buffer layer forming step, at least part of the first buffer layer is formed at a film forming temperature equal to or higher than the film forming temperature in the first functional layer forming step. .. The method further includes a second buffer layer forming step of forming a second buffer layer having a lower density than that of the first functional layer on the surface of the first functional layer using the same material as that of the first buffer layer. The thin film forming method according to claim 1, wherein the film forming temperature in the second buffer layer forming step is lower than the film forming temperature in the first functional layer forming step. In the first buffer layer step, the film forming temperature at least at the stage when the formation of the first buffer layer is completed is lower than the film forming temperature in the first functional layer forming step. 3. The thin film forming method as described in 1 or 2. The thin film forming method according to claim 1, wherein the base material is formed of resin. The thin film forming method according to claim 1, wherein the first buffer layer and the second buffer layer contain hydrogen and carbon. Base material,
A first buffer layer, which is a thin film formed on the surface of the substrate,
A first functional layer formed on the surface of the first buffer layer, which is a thin film having a density higher than that of the first buffer layer;
A second buffer layer, which is the same material as the first buffer layer and is a thin film formed on the surface of the first functional layer;
A film-forming substrate having
The first buffer layer and the second buffer layer contain hydrogen and carbon, the hydrogen concentration of the first buffer layer is lower than the hydrogen concentration of the second buffer layer, the first buffer layer The carbon concentration of is higher than that of the second buffer layer. The hydrogen concentration of the first buffer layer is 30 at% or more and 45 at% or less,
The hydrogen concentration of the second buffer layer is 45 at% or more and 60 at% or less,
The carbon concentration of the first buffer layer is 25 at% or more and 40 at% or less,
The film-forming substrate according to claim 6, wherein the carbon concentration of the second buffer layer is 15 at% or more and 25 at% or less.

Images