JP6889022B2 - Display device manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing a display device and a display device, and can be suitably used for, for example, a method for manufacturing an organic EL display device and an organic EL display device.

As a light emitting device, an organic electroluminescence device using electroluminescence is being developed. The organic electroluminescence element is referred to as an organic EL element. Electroluminescence is a phenomenon that emits light when a voltage is applied to a substance. In particular, an element that produces this electroluminescence from an organic substance is called an organic EL element (organic electroluminescence element). The organic EL element is also called an organic light emitting diode (OLED) because it is a current injection type device and exhibits diode characteristics.

International Publication No. 2012/039310 (Patent Document 1) describes a technique relating to a method for manufacturing an organic EL element. Japanese Unexamined Patent Publication No. 2001-284042 (Patent Document 2) describes a technique relating to an organic EL device.

International Publication No. 2012/039310 Japanese Patent Application Laid-Open No. 2001-284402

Since the organic EL element is vulnerable to moisture, it is desirable to form a protective film so as to cover the organic EL element to prevent the transfer of moisture to the organic EL element. Therefore, a protective film is also used in a display device using an organic EL element, and it is desired to improve the reliability of the protective film.

Other challenges and novel features will become apparent from the description and accompanying drawings herein.

According to one embodiment, the method of manufacturing a display device having an organic EL element is as follows: (a) a step of forming the organic EL element on a flexible substrate, and (b) inorganic insulation so as to cover the organic EL element. It has a step of forming a protective film made of a material. The (b) step is (b1) a step of forming a first insulating film by using a plasma ALD method so as to cover the organic EL element, and (b2) a second insulating film is formed on the first insulating film. It has a step of forming by using a plasma CVD method, and (b3) a step of forming a third insulating film on the second insulating film by using a plasma ALD method. The protective film is formed by a laminated film composed of the first insulating film, the second insulating film, and the third insulating film.

According to one embodiment, the reliability of the protective film of the display device having the organic EL element can be improved.

It is a top view which shows the whole structure of the display device of one Embodiment. It is a main part plan view of the display device of one Embodiment. It is sectional drawing of the main part of the display device of one Embodiment. It is sectional drawing which shows typically the case where the flexible substrate is used as the substrate of the display device, and the flexible substrate (display device) is bent. It is a process flow diagram which shows the manufacturing process of the display device of one Embodiment. It is a process flow diagram which shows the protective film forming process in the manufacturing process of the display device of one Embodiment. It is sectional drawing of the main part in the manufacturing process of the display device of one Embodiment. It is sectional drawing of the main part in the manufacturing process of the display device following FIG. It is sectional drawing of the main part in the manufacturing process of the display device following FIG. It is sectional drawing of the main part in the manufacturing process of the display device following FIG. It is sectional drawing of the main part in the manufacturing process of the display device following FIG. It is sectional drawing of the main part in the manufacturing process of the display device following FIG. It is sectional drawing of the main part in the manufacturing process of the display device following FIG. It is sectional drawing of the main part in the manufacturing process of the display device following FIG. It is explanatory drawing which shows an example of the film forming apparatus for forming a protective film. It is sectional drawing which shows an example of the structure of the film formation chamber using the plasma CVD method. It is sectional drawing which shows an example of the structure of the film formation chamber using the plasma ALD method. It is sectional drawing which shows the cross-sectional structure of a protective film. It is sectional drawing which shows the cross-sectional structure of a protective film. It is sectional drawing which shows the cross-sectional structure of a protective film. It is sectional drawing which shows the cross-sectional structure of a protective film. It is a graph which shows the result of having investigated the correlation between the density and stress of the film formed by the plasma ALD method. It is a table which shows the result of having investigated the number of cracks of the protective film after a bending test. It is sectional drawing which shows the cross-sectional structure of the protective film of the modification.

Hereinafter, embodiments will be described in detail with reference to the drawings. In all the drawings for explaining the embodiment, the members having the same function are designated by the same reference numerals, and the repeated description thereof will be omitted. Further, in the following embodiments, the description of the same or similar parts is not repeated in principle except when it is particularly necessary.

(Embodiment)
<About the overall structure of the display device>
The display device of the present embodiment is an organic EL display device (organic electroluminescence display device) using an organic EL element. The display device of this embodiment will be described with reference to the drawings.

FIG. 1 is a plan view showing the overall configuration of the display device 1 of the present embodiment.

The display device 1 shown in FIG. 1 has a display unit 2 and a circuit unit 3. A plurality of pixels are arranged in an array on the display unit 2, and an image can be displayed. Various circuits are formed in the circuit unit 3 as needed, and for example, a drive circuit or a control circuit is formed. The circuit in the circuit unit 3 is connected to the pixels of the display unit 2 as needed. The circuit unit 3 can also be provided outside the display device 1. Various shapes can be adopted as the planar shape of the display device 1, and the display device 1 is, for example, rectangular.

FIG. 2 is a plan view of a main part of the display device 1, and FIG. 3 is a cross-sectional view of the main part of the display device 1. FIG. 2 shows an enlarged part of the display unit 2 of the display device 1 (region 4 shown in FIG. 1). FIG. 3 substantially corresponds to the cross-sectional view taken along the line A1-A1 of FIG.

The substrate 11 constituting the base of the display device 1 has an insulating property. Further, the substrate 11 is a flexible substrate (film substrate) and has flexibility. Therefore, the substrate 11 is a flexible substrate having an insulating property, that is, a flexible insulating substrate. The substrate 11 may have further translucency. As the substrate 11, for example, a film-shaped plastic substrate (plastic film) can be used. The substrate 11 exists on the entire plane of the display device 1 of FIG. 1 and constitutes the lowermost layer of the display device 1. Therefore, the planar shape of the substrate 11 is substantially the same as the planar shape of the display device 1, and various shapes can be adopted, but for example, it can be rectangular. Of the two main surfaces of the substrate 11 located on opposite sides of each other, the main surface on the side where the organic EL element is arranged, that is, the passivation film 12, the electrode layer 13, the organic layer 14, the electrode layer 15, and the protection described later. The main surface on the side where the film 16 is formed is referred to as the upper surface of the substrate 11. Further, the main surface of the substrate 11 opposite to the upper surface is referred to as the lower surface of the substrate 11.

A passivation film (passivation layer) 12 is formed on the upper surface of the substrate 11. The passivation film 12 is made of an insulating material (insulating film), for example, a silicon oxide film. The passivation film 12 may not be formed, but it is more preferable to form the passivation film 12. The passivation film 12 can be formed over substantially the entire upper surface of the substrate 11.

The passivation film 12 has a function of preventing (blocking) the transmission of water from the substrate 11 side to the organic EL element (particularly the organic layer 14). Therefore, the passivation film 12 can function as a protective film on the lower side of the organic EL element. On the other hand, the protective film 16 can function as a protective film on the upper side of the organic EL element, and has a function of preventing (blocking) the transmission of water from the upper side to the organic EL element (particularly the organic layer 14). ..

An organic EL element is formed on the upper surface of the substrate 11 via a passivation film 12. The organic EL element is composed of an electrode layer 13, an organic layer 14, and an electrode layer 15. That is, the electrode layer 13, the organic layer 14, and the electrode layer 15 are formed (laminated) in order from the bottom on the passivation film 12 on the substrate 11, and these electrode layer 13, the organic layer 14, and the electrode layer 15 are formed in this order. As a result, an organic EL element is formed.

The electrode layer 13 is a lower electrode layer, and the electrode layer 15 is an upper electrode layer. The electrode layer 13 constitutes one of the anode and the cathode, and the electrode layer 15 constitutes the other of the anode and the cathode. That is, when the electrode layer 13 is an anode (anode layer), the electrode layer 15 is a cathode (cathode layer), and when the electrode layer 13 is a cathode (cathode layer), the electrode layer 15 is an anode (anode layer). is there. The electrode layer 13 and the electrode layer 15 are each made of a conductive film.

One of the electrode layer 13 and the electrode layer 15 is preferably formed of a metal film such as an aluminum (Al) film so that it can function as a reflective electrode, and the other of the electrode layer 13 and the electrode layer 15 is formed. Is preferably formed of a transparent conductor film made of ITO (indium tin oxide) or the like so that it can function as a transparent electrode. When adopting the so-called bottom emission method of extracting light from the lower surface side of the substrate 11, the electrode layer 13 can be a transparent electrode, and when adopting the so-called top emission method of extracting light from the upper surface side of the substrate 11. Can make the electrode layer 15 a transparent electrode. When the bottom emission method is adopted, a transparent substrate (transparent flexible substrate) having translucency can be used as the substrate 11.

Since the electrode layer 13 is formed on the passivation film 12 on the substrate 11, the organic layer 14 is formed on the electrode layer 13, and the electrode layer 15 is formed on the organic layer 14, the electrode layer 13 and the electrode layer 15 are formed. An organic layer 14 is interposed between the two.

The organic layer 14 includes at least an organic light emitting layer. In addition to the organic light emitting layer, the organic layer 14 can further include any layer of a hole transport layer, a hole injection layer, an electron transport layer, and an electron injection layer, if necessary. Therefore, the organic layer 14 is, for example, a single layer structure of an organic light emitting layer, a laminated structure of a hole transport layer, an organic light emitting layer, and an electron transport layer, or a hole injection layer, a hole transport layer, an organic light emitting layer, and electron transport. It can have a laminated structure of a layer and an electron injection layer.

The electrode layer 13 has, for example, a striped pattern extending in the X direction. That is, the electrode layer 13 has a configuration in which a plurality of line-shaped electrodes (electrode patterns) 13a extending in the X direction are arranged at predetermined intervals in the Y direction. The electrode layer 15 has, for example, a striped pattern extending in the Y direction. That is, the electrode layer 15 has a configuration in which a plurality of line-shaped electrodes (electrode patterns) 15a extending in the Y direction are arranged at predetermined intervals in the X direction. That is, the electrode layer 13 is composed of a striped electrode group extending in the X direction, and the electrode layer 15 is composed of a striped electrode group extending in the Y direction. Here, the X direction and the Y direction are directions that intersect each other, and more specifically, directions that are orthogonal to each other. Further, the X direction and the Y direction are also directions substantially parallel to the upper surface of the substrate 11.

Since the extending direction of each electrode 15a constituting the electrode layer 15 is the Y direction and the extending direction of each electrode 13a constituting the electrode layer 13 is the X direction, the electrodes 15a and 13a are viewed in a plan view. They intersect each other. In addition, the plan view means the case where it is viewed in a plane substantially parallel to the upper surface of the substrate 11. At each intersection of the electrode 15a and the electrode 13a, the organic layer 14 is vertically sandwiched between the electrode 15a and the electrode 13a. Therefore, an organic EL element (organic EL element constituting a pixel) composed of the electrode 13a, the electrode 15a, and the organic layer 14 between the electrodes 13a and 15a is formed at each intersection of the electrode 15a and the electrode 13a. , The organic EL element forms a pixel. By applying a predetermined voltage between the electrodes 15a and 13a, the organic light emitting layer in the organic layer 14 sandwiched between the electrodes 15a and 13a can emit light. That is, the organic EL element constituting each pixel can emit light. The electrode 15a functions as the upper electrode (one of the anode and the cathode) of the organic EL element, and the electrode 13a functions as the lower electrode (the other of the anode and the cathode) of the organic EL element.

The organic layer 14 can be formed over the entire display unit 2, but can also be formed as the same pattern as the electrode layer 13 (that is, the same pattern as the plurality of electrodes 13a constituting the electrode layer 13), or can be formed. It can also be formed as the same pattern as the electrode layer 15 (that is, the same pattern as the plurality of electrodes 15a constituting the electrode layer 15). In any case, the organic layer 14 is present at each intersection of the plurality of electrodes 13a constituting the electrode layer 13 and the plurality of electrodes 15a constituting the electrode layer 15.

As described above, in the plan view, the display unit 2 of the display device 1 is in a state in which a plurality of organic EL elements (pixels) are arranged in an array on the substrate 11 in the plan view.

Here, the case where the electrode layers 13 and 15 have a striped pattern has been described. Therefore, in the plurality of organic EL elements (pixels) arranged in an array, the lower electrodes (electrodes 13a) are connected to each other among the organic ELs arranged in the X direction, and the organic ELs arranged in the Y direction are connected to each other. Then, the upper electrodes (electrodes 15a) are connected to each other. However, the structure of the organic EL elements arranged in an array is not limited to this, and can be variously changed.

For example, a plurality of organic EL elements arranged in an array may not be connected to each other in either the upper electrode or the lower electrode, and may be arranged independently. In this case, each organic EL element is formed by an isolated pattern having a laminated structure of a lower electrode, an organic layer, and an upper electrode, and a plurality of the isolated organic EL elements are arranged in an array. In this case, in addition to the organic EL element, an active element such as a TFT (thin film transistor) can be provided in each pixel, and the pixels can be connected to each other via wiring if necessary.

A protective film (protective layer) 16 is formed on the upper surface of the substrate 11 (passivation film 12) so as to cover the organic EL element, and thus to cover the electrode layer 13, the organic layer 14, and the electrode layer 15. There is. When the organic EL elements are arranged in an array on the display unit 2, the protective film 16 is formed so as to cover the organic EL elements arranged in the array. Therefore, the protective film 16 is preferably formed on the entire display portion 2, and is preferably formed on substantially the entire upper surface of the substrate 11. By covering the organic EL element (electrode layer 13, organic layer 14 and electrode layer 15) with the protective film 16, the organic EL element (electrode layer 13, organic layer 14 and electrode layer 15) is protected, and the organic EL element is also protected. The transfer of water to the organic layer 14, particularly the transfer of water to the organic layer 14, can be prevented (blocked) by the protective film 16. That is, by providing the protective film 16, it is possible to prevent moisture from entering the organic EL element side beyond the protective film 16. The protective film 16 is a protective film for an organic EL element.

However, it may be necessary to expose a part of the electrode or wiring from the protective film 16. In such a case, instead of forming the protective film 16 in the entire area on the upper surface side of the substrate 11, a region in which the protective film 16 is not formed is provided in a part of the upper surface side of the substrate 11 and there (protective film). A part such as an electrode or a wiring can be exposed from the region where 16 is not formed). However, even in such a case, it is preferable that the organic layer 14 is not exposed from the region where the protective film 16 is not formed.

The protective film 16 is made of an inorganic insulating material so as to obtain a barrier property against moisture. That is, the protective film 16 is an inorganic insulating film. However, the protective film 16 is not a single-layer insulating film, but a laminated insulating film in which a plurality of insulating films (inorganic insulating films) are laminated.

In the present embodiment, the protective film 16 includes an insulating film (inorganic insulating film, insulating layer) 16a, an insulating film (inorganic insulating film, insulating layer) 16b on the insulating film 16a, and an insulating film (inorganic insulating film, insulating layer) 16b. It is composed of a laminated film with an inorganic insulating film and an insulating layer) 16c. That is, the protective film 16 has three layers of an insulating film 16a, an insulating film 16b, and an insulating film 16c.

Of the insulating films 16a, 16b, and 16c constituting the protective film 16, the insulating film 16a and the insulating film 16c are insulating films formed by the plasma ALD (Atomic Layer Deposition) method, respectively, and are insulated. The film 16b is an insulating film formed by a plasma CVD (Chemical Vapor Deposition) method. The ALD method is a film forming method for forming a film on an atomic layer unit on an object to be treated by alternately supplying a raw material gas and a reaction gas. Further, as a plasma CVD method for forming the insulating film 16b, an ICP (Inductively Coupled Plasma) -CVD method (inductively coupled plasma CVD method) can be preferably used.

As the insulating film 16b, a silicon nitride film, a silicon oxide film or a silicon oxynitride film can be preferably used, but a silicon nitride film is most preferable. As the insulating film 16a, an insulating film containing aluminum (Al) can be used. For example, an aluminum oxide film, an aluminum nitride film, or an aluminum nitride film can be preferably used. Among them, an aluminum oxide film. Is particularly preferable. Similarly, as the insulating film 16c, an insulating film containing aluminum (Al) can be used, and for example, an aluminum oxide film, an aluminum nitride film, or an aluminum nitride film can be preferably used. An aluminum oxide film is particularly preferable.

A resin film (resin layer, resin insulating film, organic insulating film) 17 is formed on the protective film 16. That is, the resin film 17 is formed on the insulating film 16c. The resin film 17 can also be regarded as an organic insulating film. As the material of the resin film 17, for example, PET (polyethylene terephthalate) or the like can be preferably used.

The formation of the resin film 17 may be omitted. However, the case where the resin film 17 is formed is more preferable than the case where the resin film 17 is not formed. Since the resin film 17 is soft, the display device 1 can be easily handled by providing the resin film 17.

The protective film 16 is an inorganic insulating film. The inorganic insulating film is a film that does not allow moisture to pass through, but is also a hard film. Therefore, the resin film 17 can be formed on the protective film 16, and the resin film 17 can be used as the uppermost film of the display device 1. Since the resin film (17) allows moisture to pass through more easily than the inorganic insulating film (protective film 16), the function as a film for preventing the invasion of moisture is small. However, the resin film (17) is softer than the inorganic insulating film (protective film 16). Therefore, by forming the soft resin film 17 on the protective film 16, the display device 1 can be easily handled. Further, the resin film 17 can function as a protective film (mechanical protective film) from a physical impact.

Further, when the resin film 17 is formed on the protective film 16, the combination of the protective film 16 and the resin film 17 can be regarded as the protective film. However, when the resin film 17 is formed, it is the protective film 16 that functions as a film (moisture prevention film) that prevents the intrusion of moisture, and the resin film 17 mainly functions as a mechanical protective film. It is preferable that the moisture protective film (here, the protective film 16) is made of an inorganic insulator, and the mechanical protective film (here, the resin film 17) is made of a resin material (organic insulator).

In this embodiment, a flexible substrate is used as the substrate 11 of the display device 1. FIG. 4 is a cross-sectional view schematically showing a case where the substrate 11 (flexible substrate) constituting the display device 1 is bent, that is, a case where the display device 1 is bent. FIG. 4 is a cross-sectional view, but hatching is omitted in order to make the drawing easier to see. By using a flexible substrate as the substrate 11 of the display device 1, the display device 1 can be bent. Further, although the substrate 11 is a flexible substrate, it can be repeatedly folded and can be regarded as a bendable substrate, can also be folded, and can be regarded as a foldable substrate. it can. Therefore, the substrate 11 is a flexible substrate, and the flexible substrate also includes a bendable substrate and a foldable substrate.

<Manufacturing method of display device>
The manufacturing method of the display device 1 of the present embodiment will be described with reference to the drawings. FIG. 5 is a process flow chart showing a manufacturing process of the display device 1 of the present embodiment. FIG. 6 is a process flow chart showing details of the protective film 16 forming step in the manufacturing process of the display device 1 of the present embodiment. 7 to 14 are cross-sectional views of a main part of the display device 1 of the present embodiment during the manufacturing process, and a cross-sectional view of a region corresponding to FIG. 3 is shown. Here, the manufacturing process of the display unit 2 of the display device 1 will be mainly described.

First, as shown in FIG. 7, a substrate 10 in which a glass substrate 9 and a flexible substrate 11 are bonded to each other is prepared (prepared) (step S1 in FIG. 5). Although the substrate 11 has flexibility, the substrate 11 is fixed to the glass substrate 9 because the substrate 11 is attached to the glass substrate 9. This facilitates the formation of various films on the substrate 11 and the processing of the films. The lower surface of the substrate 11 is attached to the glass substrate 9.

Next, as shown in FIG. 8, a passivation film 12 is formed on the upper surface of the substrate 10 (step S2 in FIG. 5). The upper surface of the substrate 10 has the same meaning as the upper surface of the substrate 11.

The passivation film 12 can be formed by using a sputtering method, a CVD method, an ALD method, or the like. The passivation film 12 is made of an insulating material, for example, a silicon oxide film. For example, the silicon oxide film formed by the CVD method can be suitably used as the passivation film 12.

Next, as shown in FIG. 9, the organic composition of the electrode layer 13, the organic layer 14 on the electrode layer 13, and the electrode layer 15 on the organic layer 14 on the upper surface of the substrate 10, that is, on the passivation film 12. Form an EL element. That is, the electrode layer 13, the organic layer 14, and the electrode layer 15 are sequentially formed on the passivation film 12 (steps S3, S4, and S5 in FIG. 5). This step can be performed, for example, as follows.

That is, the electrode layer 13 is formed on the upper surface of the substrate 10, that is, on the passivation film 12 (step S3 in FIG. 5). The electrode layer 13 can be formed, for example, by forming a conductive film on the passivation film 12 and then patterning the conductive film using a photolithography technique, an etching technique, or the like. Then, the organic layer 14 is formed on the electrode layer 13 (step S4 in FIG. 5). The organic layer 14 can be formed by, for example, a vapor deposition method using a mask (vacuum vapor deposition method). It is also possible to form the organic layer 14 by forming a film for the organic layer 14 and then patterning the film using a photolithography technique, an etching technique, or the like. Then, the electrode layer 15 is formed on the organic layer 14 (step S5 in FIG. 5). The electrode layer 15 can be formed by, for example, a vapor deposition method using a mask. It is also possible to form the electrode layer 15 by forming a film for the electrode layer 15 and then patterning the film using a photolithography technique, an etching technique, or the like.

After forming the organic EL element composed of the electrode layer 13, the organic layer 14, and the electrode layer 15, the protective film 16 is formed on the upper surface of the substrate 10, that is, on the electrode layer 15 (step S6 in FIG. 5). The protective film 16 is formed so as to cover the organic EL element.

Since the protective film 16 is composed of a laminated film of the insulating film 16a, the insulating film 16b on the insulating film 16a, and the insulating film 16c on the insulating film 16b, the step of forming the protective film 16 in step S6 is as shown in FIG. It also has an insulating film 16a forming step of step S6a, an insulating film 16b forming step of step S6b, and an insulating film 16c forming step of step S6c. Step S6b is performed after step S6a, and then step S6c is performed.

Therefore, the step of forming the protective film 16 in step S6 can be specifically performed as follows. That is, first, as shown in FIG. 10, an insulating film 16a is formed on the substrate 10, that is, on the electrode layer 15 by using the plasma ALD method (step S6a in FIG. 6). The insulating film 16a is formed so as to cover the organic EL element. Then, as shown in FIG. 11, the insulating film 16b is formed on the insulating film 16a by using the plasma CVD method (step S6b in FIG. 6). Then, as shown in FIG. 12, the insulating film 16c is formed on the insulating film 16b by using the plasma ALD method (step S6c in FIG. 6). As a result, the protective film 16 composed of a laminated film of the insulating film 16a, the insulating film 16b, and the insulating film 16c is formed.

In addition, it may be necessary to expose a part of the electrode or wiring from the protective film 16. In such a case, instead of forming the protective film 16 on the entire upper surface of the substrate 10, a region where the protective film 16 is not formed is provided on a part of the upper surface of the substrate 10 and there (the protective film 16 is formed). A part such as an electrode or a wiring can be exposed from the non-existing area). In this case, the protective film 16 forming step of step S6 can be performed, for example, as follows.

That is, first, a mask (metal mask) is placed on the substrate 10, that is, on the electrode layer 15, and then the insulating film 16a is formed as step S6a by using the plasma ALD method. Then, after removing the mask, the next mask (metal mask) is placed on the substrate 10, that is, on the electrode layer 15, and then the insulating film 16b is placed on the insulating film 16a as step S6b by the plasma CVD method. To form. Then, after removing the mask, the next mask (metal mask) is placed on the substrate 10, that is, on the electrode layer 15, and then the insulating film 16c is placed on the insulating film 16b as step S6c by the plasma ALD method. And then remove the mask. As a result, the protective film 16 composed of a laminated film of the insulating film 16a, the insulating film 16b, and the insulating film 16c is formed. Insulating films 16a, 16b, 16c are formed in the exposed region without being covered with the mask, and thus the protective film 16 is formed, but the insulating films 16a, 16b are formed in the region covered with the mask. , 16c are not formed, and therefore the protective film 16 is not formed. As a result, the protective film 16 can be formed so as to cover the organic EL element, and the electrodes, wirings, and the like can be exposed as necessary from the region where the protective film 16 is not formed.

In any case, in steps S6a and S6c, the insulating films 16a and 16c are formed by using the plasma ALD method, and in steps S6b, the insulating films 16b are formed by using the plasma CVD method. It is more preferable to use the ICP-CVD method as the plasma CVD method in step S6b.

Although the details will be described later, the insulating film 16a and the insulating film 16c are formed to relax (cancel) the stress of the insulating film 16b, and the protective film 16 sandwiches the insulating film 16b between the insulating film 16a and the insulating film 16c. It has a structure. Therefore, in step S6b, the insulating film 16b is formed on the insulating film 16a so as to be in contact with the insulating film 16a, and in step S6c, the insulating film 16c is in contact with the insulating film 16b on the insulating film 16b. Is formed as follows. Therefore, when steps S6a, S6b, and S6c are completed, a protective film 16 composed of a laminated film of the insulating film 16a, the insulating film 16b, and the insulating film 16c is formed, and the insulating film 16b is formed on the insulating film 16a. It is in contact with the insulating film 16a, and the insulating film 16c is formed on the insulating film 16b and is in contact with the insulating film 16b. In step S6a, the insulating film 16c is formed so as to cover the organic EL element, and therefore the protective film 16 is formed so as to cover the organic EL element.

Since the organic EL element (particularly the organic layer 14) is vulnerable to high temperatures, the film formation temperatures of steps S6a, S6b, and S6c, that is, the film formation temperatures of the insulating films 16a, 16b, and 16c are set to the organic EL element (particularly the organic layer 14). ), It is preferable that the temperature is relatively low, and specifically, the temperature is preferably 100 ° C. or lower, for example, about 80 ° C.

In order to enable the formation of a dense film even at such a low film formation temperature, it is preferable to use a silicon nitride film, a silicon oxide film or a silicon oxynitride film as the insulating film 16b using the plasma CVD method. Of these, a silicon nitride film is particularly preferable. Further, as the insulating films 16a and 16c using the plasma ALD method, it is preferable to use an insulating film containing aluminum (Al), and an aluminum oxide film, an aluminum nitride film or an aluminum nitride film can be preferably used. Among them, the aluminum oxide film is particularly preferable.

When the protective film 16 is formed, the organic EL element composed of the electrode layer 13, the organic layer 14, and the electrode layer 15 is covered with the protective film 16. When a plurality of organic EL elements are arranged in an array, the plurality of organic EL elements are covered with the protective film 16.

After forming the protective film 16 in step S6, the resin film 17 is formed on the upper surface of the substrate 10, that is, on the protective film 16 as shown in FIG. 13 (step S7 in FIG. 5).

Since the uppermost layer of the protective film 16 is the insulating film 16c, the resin film 17 is formed on the insulating film 16c. The resin film 17 is made of, for example, PET or the like, and can be formed by using a spin coating method (coating method) or the like.

After that, as shown in FIG. 14, the substrate 11 and the structure on the upper surface thereof are separated from the glass substrate 9 by peeling the substrate 11 from the glass substrate 9. In this way, the display device 1 can be manufactured.

<About film deposition equipment>
FIG. 15 is an explanatory diagram showing an example of a film forming apparatus for forming the protective film 16.

The film forming apparatus 21 of FIG. 15 is a multi-chamber type film forming apparatus having a plurality of chambers. Specifically, the film forming apparatus 21 has a load lock chamber 22, a transfer chamber 23, and a plurality of chambers (processing chamber, film forming chamber, film forming container) 24, 25, 26. Of these, chambers 24 and 26 are chambers in which film formation is performed using the plasma ALD method, and chamber 25 is a chamber in which film formation is performed using the plasma CVD method. The chamber 24 is used to form the insulating film 16a, the chamber 25 is used to form the insulating film 16b, and the chamber 26 is used to form the insulating film 16c. The process flow for forming the protective film 16 using the film forming apparatus 21 will be described below.

First, after completing the steps prior to the protective film 16 forming step, the object to be processed is carried into the load lock chamber 22 of the film forming apparatus 21 in order to perform the protective film 16 forming step. Here, the object to be processed to be carried into the load lock chamber 22 is the substrate 10 on which the passivation film 12, the electrode layer 13, the organic layer 14, the electrode layer 15, and the like are formed, and the structure of FIG. 9 is formed on the substrate 10. It is formed, and in FIGS. 16 and 17, which will be described later, the object 27 is designated by reference numeral 27.

Then, the object to be processed carried into the load lock chamber 22 is conveyed (vacuum transfer) into the chamber 24 via the transfer chamber 23. Then, an insulating film 16a is formed on the object to be processed arranged in the chamber 24 by using the plasma ALD method. In this case, step S6a is performed in the chamber 24. Then, the object to be processed in the chamber 24 is transferred (vacuum transfer) into the chamber 25 via the transfer chamber 23. Then, the insulating film 16b is formed on the object to be processed arranged in the chamber 25 by using the plasma CVD method. In this case, step S6b is performed in the chamber 25. Then, the object to be processed in the chamber 25 is transferred (vacuum transfer) into the chamber 26 via the transfer chamber 23. Then, an insulating film 16c is formed on the object to be processed arranged in the chamber 26 by using the plasma ALD method. In this case, the step S6c is performed in the chamber 26. Then, the object to be processed in the chamber 26 is transferred (vacuum transfer) to the load lock chamber 22 via the transfer chamber 23. After that, the object to be processed is carried out of the film forming apparatus 21 from the load lock chamber 22 and conveyed to the manufacturing apparatus for performing the next step (for example, the resin film 17 forming step).

Further, the film forming apparatus 21 may be provided with two load lock chambers, a load lock chamber for carrying in and a load lock chamber for carrying out. In that case, the object to be processed is carried into the load lock chamber for carrying in, processed in steps S6a, S6b, S6c in chambers 24, 25, and 26 via the transfer chamber 23, and then for carrying out. It is carried out of the film forming apparatus 21 from the load lock chamber and sent to the next process.

Further, in each of the film forming steps of the insulating films 16a, 16b, 16c, when the film is formed with the mask placed on the object to be processed, the transfer chamber 23 is connected to the mask attachment / detachment chamber (mask chamber). The mask can be attached and detached in the mask chamber.

Using the film forming apparatus 21 of FIG. 15, the step S6a (insulating film 16a forming step), the step S6b (insulating film 16b forming step), and the step S6c (insulating film 16c forming step) can be processed. It can be done continuously without exposing the object to the atmosphere. As a result, after the insulating film 16a is formed in step S6a, the insulating film 16b can be formed on the insulating film 16a in step S6b without forming an unnecessary film on the surface of the insulating film 16a. After the insulating film 16b is formed in step S6b, the insulating film 16c can be formed on the insulating film 16b in step S6c without forming an unnecessary film on the surface of the insulating film 16b. As a result, the protective film 16 composed of the insulating film 16a, the insulating film 16b, and the insulating film 16c can be formed more accurately, and the effect of preventing the intrusion of moisture can be obtained more accurately by the protective film 16. it can.

FIG. 16 is a cross-sectional view showing an example of the configuration of the chamber 25 for forming a film by the plasma CVD method. Although the chamber 25 is a chamber in which film formation is performed using the plasma CVD method, it can also be regarded as a film forming apparatus for forming a film using the plasma CVD method, and therefore, a plasma CVD device or a plasma CVD film forming apparatus. Can also be regarded as.

As shown in FIG. 16, in the chamber 25, a stage 31 for arranging the object to be processed 27, a shower head (gas supply unit) 32 arranged above the stage 31, and a shower head 32 below the shower head 32. The antenna 33 and the antenna 33 arranged in the above are arranged. The antenna 33 is arranged near the shower head 32 between the stage 31 and the shower head 32. In FIG. 16, in the chamber 25, the antenna 33 extends in a direction substantially perpendicular to the paper surface. The exhaust portion (exhaust port) 34 of the chamber 25 is connected to a vacuum pump (not shown) or the like so that the inside of the chamber 25 can be controlled to a predetermined pressure.

At the time of film formation using the chamber 25, the film-forming gas is discharged from the shower head 32 into the chamber 25, and high-frequency power is applied to the antenna 33. When forming a silicon nitride film, for example, _{a mixed gas of SiH 4} gas (silane gas) and NH ₃ gas (ammonia gas) can be used as the film forming gas. The gas is turned into plasma and chemically reacted, and the generated SiN (silicon nitride) particles are deposited on the object to be processed 27 arranged on the stage 31 to form a silicon nitride film. The film (for example, silicon nitride film) formed on the object 27 to be processed in the chamber 25 corresponds to the insulating film 16b.

FIG. 17 is a cross-sectional view showing an example of the configuration of the chamber 24 for forming a film by the plasma ALD method. Since the configuration of the chamber 26 is the same as that of the chamber 24 of FIG. 17, here, the configuration of the chamber 24 will be described with reference to FIG. 17 on behalf of the chambers 24 and 26. Each of the chambers 24 and 26 is a chamber in which film formation is performed using the plasma ALD method, but can also be regarded as a film forming device that performs film formation using the plasma ALD method, and therefore, a plasma ALD device or plasma. It can also be regarded as an ALD film forming apparatus.

Further, in the present embodiment, it is preferable to use the plasma ALD method as the ALD method for forming the insulating films 16a and 16c. Therefore, in the chambers 24 and 26, a film formation using the plasma ALD method is performed. Is preferable. In the plasma ALD apparatus (chambers 24 and 26), in order to enhance the reaction activity, plasma discharge is performed to turn the reaction gas into plasma. Therefore, in the plasma ALD apparatus (chambers 24 and 26), a parallel plate electrode or the like is used to perform plasma discharge.

As shown in FIG. 17, a stage 41 for arranging the object to be processed 27 and an upper electrode (plate electrode) 42 arranged above the stage 41 are arranged in the chamber 24. A high-frequency power supply 46 is connected to the upper electrode 42, and the high-frequency power supply 46 enables high-frequency power to be applied to the upper electrode 42, and thus between the upper electrode 42 and the stage 41. The stage 41 also has a function as a lower electrode. A parallel plate electrode is formed by the upper electrode 42 and the lower electrode (here, the stage 41). The high frequency power supply 46 can be arranged outside the chamber 24. The stage 41 is provided with a heater (not shown) or the like, and can heat the processing object 27 arranged on the stage 41 and adjust the temperature of the processing object 27 to a desired temperature. There is. The exhaust portion (exhaust port) 43 of the chamber 24 is connected to a vacuum pump (not shown) or the like so that the inside of the chamber 24 can be controlled to a predetermined pressure. Further, the chamber 24 has a gas introduction unit 44 for introducing gas into the chamber 24 and a gas discharge unit (gas exhaust unit) 45 for discharging gas from the chamber 24. In FIG. 17, for the sake of simplicity, the flow of gas introduced into the chamber 24 from the gas introduction unit 44 and the flow of gas discharged from the gas discharge unit 45 to the outside of the chamber 24 are indicated by arrows. It is shown schematically.

Although FIG. 17 shows a film forming apparatus using a parallel plate type electrode for plasma generation, as another form, a method other than the parallel plate type (for example, ICP (Inductively Coupled Plasma)) is used for plasma generation. Mold) can also be used.

The film formation using the chamber 24 (the film formation by the plasma ALD method) can be performed, for example, as follows.

With the processing object 27 arranged on the stage 41 in the chamber 24, the processing object 27 is repeated by repeating the first step, the second step, the third step, and the fourth step described below for a plurality of cycles. A desired film (eg, an aluminum oxide film) can be formed on the surface of the surface to a desired thickness. Hereinafter, a specific description will be given.

First, as the first step (raw material gas supply step), the raw material gas is introduced (supplied) into the chamber 24 from the gas introduction unit 44. When forming an aluminum oxide film, for example, TMA (Trimethylaluminium) gas can be used as the raw material gas. When the first step is performed, the molecules of the raw material gas are adsorbed on the surface of the object to be processed 27 arranged on the stage 41. That is, an adsorption layer of the raw material gas is formed on the surface of the object to be treated 27.

Next, as the second step (purge step), the introduction of the raw material gas into the chamber 24 is stopped, and the purge gas is introduced (supplied) into the chamber 24 from the gas introduction unit 44. As the purge gas, an inert gas can be preferably used, but nitrogen gas (N ₂ gas) may also be used. By introducing the purge gas, the raw material gas molecules (adsorption layer of the raw material gas) adsorbed on the surface of the object to be treated 27 remain, but the other raw material gas is removed from the gas discharge unit 45 together with the purge gas in the chamber. 24 It is discharged (purged) to the outside.

Next, as a third step (reaction gas supply step), the reaction gas is introduced (supplied) into the chamber 24 from the gas introduction unit 44. When forming an aluminum oxide film, for example, O ₂ gas (oxygen gas) can be used as the reaction gas. Then, high frequency power is applied to the upper electrode 42, and thus between the upper electrode 42 and the stage 41. Thus, plasma discharge is generated between the upper electrode 42 and the stage 41, the reaction gas (O ₂ gas in this case) is converted into plasma, radicals (active species) are generated in the reaction gas, the processing target 27 The raw material gas molecules (adsorbed layer of the raw material gas) adsorbed on the surface react with the reaction gas. As a result, an atomic layer (layer) of aluminum oxide, which is a reaction layer of the adsorption layer of the raw material gas and the reaction gas (plasma of the reaction gas), is formed on the surface of the object 27 to be treated.

Next, as a fourth step (purge step), the introduction of the reaction gas into the chamber 24 and the application of high-frequency power to the upper electrode 42 are stopped, and the purge gas is introduced (supplied) into the chamber 24 from the gas introduction unit 44. To do. As the purge gas, an inert gas can be preferably used, but nitrogen gas (N ₂ gas) may also be used. By introducing the purge gas, the reaction gas is discharged (purged) from the gas discharge unit 45 to the outside of the chamber 24 together with the purge gas.

By repeating such a first step, a second step, a third step, and a fourth step for a plurality of cycles, a desired film (for example, an aluminum oxide film) is formed on the surface of the object to be treated 27 to a desired thickness. Can be formed. For example, if the first step, the second step, the third step, and the fourth step are repeated for 30 cycles, a film consisting of 30 atomic layers is formed, and the first step, the second step, the third step, and the like. If the fourth step is repeated for 60 cycles, a film composed of 60 atomic layers will be formed.

Since the film formation using the chamber 26 (deposition by the plasma ALD method) is basically the same as the film formation using the chamber 24 (deposition by the plasma ALD method), the description thereof will be omitted here. The film formed on the surface of the object to be treated 27 in the chamber 24 (for example, an aluminum oxide film) corresponds to the insulating film 16a, and the film formed on the surface of the object to be treated 27 in the chamber 26 (for example,). The aluminum oxide film) corresponds to the insulating film 16c.

When the insulating film 16a formed in the chamber 24 is an aluminum oxide film, the following conditions can be exemplified as the film forming conditions of the aluminum oxide film. That is, the substrate temperature (deposition temperature) is 80 ° C., the flow rate of TMA gas is 50 _{sccm, the flow rate of O 2} gas is 300 sccm, the RF power (high frequency power) is 750 W, and the film formation rate is 4 nm / min. ..

When the insulating film 16b formed in the chamber 25 is a silicon nitride film, the following conditions can be exemplified as the film forming conditions of the silicon nitride film. That is, the substrate temperature (deposition temperature) is 80 ° C., _{the flow rate of SiH 4} gas is 100 sccm, the flow rate of NH ₃ gas is 150 sccm, the RF power (high frequency power) is 1000 W, and the film formation rate is 100 nm / min. is there.

When the insulating film 16c formed in the chamber 26 is an aluminum oxide film, the following conditions can be exemplified as the film forming conditions of the aluminum oxide film. That is, the substrate temperature (deposition temperature) is 80 ° C., the flow rate of TMA gas is 50 _{sccm, the flow rate of O 2} gas is 300 sccm, the RF power (high frequency power) is 750 W, and the film formation rate is 4 nm / min. ..

<Background of examination>
Since the organic EL element is sensitive to moisture, it is desirable to form a protective film (moisture protective film) so as to cover the organic EL element to prevent the transfer of moisture to the organic EL element. For this protective film, it is desirable to use an inorganic insulating film having a high effect of preventing the invasion of moisture. Further, since the organic EL element is vulnerable to high temperatures, the film formation temperature of the protective film is preferably relatively low so as not to adversely affect the organic EL element. Therefore, the protective film has a relatively low temperature. It is preferable to use a material film capable of forming a film.

By the way, the present inventor is considering using a flexible substrate as a substrate for forming an organic EL element. Since the flexible substrate has flexibility, it can be bent. If a flexible substrate is used as the substrate of the organic EL display device, the display device can be bent.

When a flexible substrate is used, the protective film is also bent together with the flexible substrate, so that bending resistance is also important for the protective film. However, although the inorganic insulating film is excellent as a protective film (moisture protective film), it is a harder material than a resin film or the like. Therefore, when a flexible substrate is used as a substrate, the inorganic insulating film is bent. There is a risk of cracking in the protective film made of. That is, when the flexible substrate is bent with a small bending radius, the protective film is also bent with a small bending radius, and there is a risk that the protective film will be cracked due to the bending. If a crack is generated in the protective film, water may invade the organic EL element side through the crack, and the water may be transmitted to the organic EL element, causing deterioration of the organic EL element. This leads to a decrease in the reliability of the organic EL element and a decrease in the reliability of the display device (organic EL display device) using the organic EL element.

Therefore, when a flexible substrate is used, it is important that the protective film (moisture protective film) not only enhances the barrier property against moisture but also enhances the bending resistance.

<Main features and effects>
One of the main features of this embodiment is that a flexible substrate is used as the substrate 11. Another of the main features of the present embodiment is that the protective film 16 made of an inorganic insulating material is an insulating film 16a formed by the plasma ALD method and an insulation formed on the insulating film 16a by the plasma CVD method. It is composed of a laminated film having a film 16b and an insulating film 16c formed on the insulating film 16b by the plasma ALD method.

In the present embodiment, since the flexible substrate is used as the substrate 11, it is desired to improve the bending resistance of the protective film 16 so that the protective film 16 does not crack due to bending. In order to realize this, in the present embodiment, the insulating film 16b formed by the plasma CVD method is sandwiched between the insulating film 16a formed by the plasma ALD method and the insulating film 16c formed by the plasma ALD method (lamination). A protective film 16 having a structure) is adopted. Thereby, the bending resistance of the protective film 16 can be improved, which will be described in detail below with reference to FIGS. 18 to 21. The bending resistance of the protective film corresponds to the durability against the bending test. Further, the bending test corresponds to a test in which the bending operation is repeated many times. It can be determined that the bending resistance of the protective film is improved if no problems such as cracks occur in the protective film even if the bending operation is repeated many times.

18 to 21 are cross-sectional views (explanatory views) showing a cross-sectional structure of the protective film, and are shown by extracting a part of the display device 1 (a part of FIG. 3 above). However, while FIG. 18 corresponds to the present embodiment, FIGS. 19, 20, and 21 correspond to the study examples examined by the present inventor. 18 to 21 show the cross-sectional structure of the protective film (16,116,216,316), but in FIGS. 18 to 21, the cross-sectional structures of the protective film are different from each other.

In FIGS. 18 to 21, the layers constituting the base layer of the protective film (16,116,216,316) are indicated by reference numerals 18 as the base layer 18, and the protective film (16,116,216) is shown. , 316) are formed on the base layer 18. The base layer 18 is composed of the electrode layer 15, the organic layer 14, the electrode layer 13, the passivation film 12 or the substrate 11, and the base layer 18 is the electrode layer 15, the organic layer 14, the electrode layer 13, and the passivation film. Whether it is composed of 12 or the substrate 11 may differ depending on the plane position of the protective film. For example, one protective film 16 includes a region in which the base layer 18 under the protective film 16 is composed of an electrode layer 15 and a region in which the base layer 18 under the protective film 16 is composed of an organic layer 14. In some cases, the base layer 18 under the protective film 16 has a region formed of the electrode layer 13 and the base layer 18 under the protective film 16 has a region formed of the passivation film 12. possible.

The structure (cross-sectional structure) of the protective film in each of FIGS. 18 to 21 is as follows.

FIG. 18 shows a cross-sectional view of the protective film 16 of the present embodiment. As shown in FIG. 18, the protective film 16 made of an inorganic insulating material includes an insulating film 16a formed by the plasma ALD method, an insulating film 16b formed on the insulating film 16a by the plasma CVD method, and an insulating film 16b. It has a laminated structure with an insulating film 16c formed on the plasma ALD method. In the laminated structure constituting the protective film 16, the insulating film 16c formed by the plasma ALD method is the uppermost layer, the insulating film 16a formed by the plasma ALD method is the lowest layer, and the insulation formed by the plasma CVD method. The film 16b is an intermediate layer.

FIG. 19 shows a cross-sectional view of the protective film 116 of the first study example. As shown in FIG. 19, the protective film 116 made of an inorganic insulating material is a film formed by a plasma CVD method and has a single-layer structure. In the case of FIG. 19 (first study example), the protective film 116 is entirely composed of the film corresponding to the insulating film 16b, and has the films corresponding to the insulating films 16a and 16c in the present embodiment. Absent.

FIG. 20 shows a cross-sectional view of the protective film 216 of the second study example. As shown in FIG. 20, the protective film 216 made of an inorganic insulating material has a laminated structure of an insulating film 216b formed by a plasma CVD method and an insulating film 216c formed on the insulating film 216b by a plasma ALD method. Have. In the laminated structure constituting the protective film 216, the insulating film 216c formed by the plasma ALD method is the uppermost layer, and the insulating film 216b formed by the plasma CVD method is the lowest layer. In the case of FIG. 20 (second study example), the protective film 216 is composed of an insulating film 216b corresponding to the insulating film 16b and an insulating film 216c corresponding to the insulating film 16c, and the film corresponding to the insulating film 16a is I don't have it.

FIG. 21 shows a cross-sectional view of the protective film 316 of the third study example. As shown in FIG. 21, the protective film 316 made of an inorganic insulating material has a laminated structure of an insulating film 316a formed by the plasma ALD method and an insulating film 316b formed on the insulating film 316a by the plasma CVD method. Have. In the laminated structure constituting the protective film 316, the insulating film 316b formed by the plasma CVD method is the uppermost layer, and the insulating film 316a formed by the plasma ALD method is the lowest layer. In the case of FIG. 21 (3rd study example), the protective film 316 is composed of an insulating film 316a corresponding to the insulating film 16a and an insulating film 316b corresponding to the insulating film 16b, and the film corresponding to the insulating film 16c is I don't have it.

By the way, as the protective film (moisture protective film) having a barrier property against moisture, a Si-containing inorganic insulating film formed by the plasma CVD method is suitable. Since the Si-containing inorganic insulating film formed by the plasma CVD method can be formed at a low temperature and the density of the film can be increased, the water transmittance per unit thickness is low, and the water content to the organic EL element is high. This is because it is suitable as a protective film that prevents transmission. Here, the Si-containing inorganic insulating film is an inorganic insulating film containing Si (silicon, silicon) as a constituent element, and examples thereof include a silicon nitride film, a silicon oxide film, and a silicon oxynitride film. In particular, the silicon nitride film is preferable as a moisture protective film because it has a very low moisture transmittance per unit thickness and has a high barrier property against moisture. This is because when the silicon nitride film is formed by the plasma CVD method, a more dense film can be formed at a low temperature.

However, it is not easy to control the stress of the film formed by the plasma CVD method. Therefore, the films (16b, 116, 216b, 316b) formed by the plasma CVD method at a temperature (preferably 100 ° C. or lower) that does not adversely affect the organic EL element are stressed films (tensile stress films). Or it is easily formed as a compressive stress film). In particular, the silicon nitride film formed by the plasma CVD method at a temperature (preferably 100 ° C. or lower) that does not adversely affect the organic EL device has a high barrier property against moisture, but has a considerably large compressive stress. Will be.

Therefore, the protective film 116 of FIG. 19 tends to have a large stress, reflecting that it is formed by the plasma CVD method. In particular, the protective film 116 is a silicon nitride film formed by the plasma CVD method. When it has a single-layer structure, the protective film 116 becomes a film having a large compressive stress.

If the protective film 116 has a compressive stress or a compressive stress, there is an increased risk that the protective film 116 will crack when the protective film 116 is bent against the stress. For example, when the protective film 116 has a compressive stress, when the display device is bent in the same direction as in the case of FIG. 4, the protective film 116 is bent against the compressive stress of the protective film 116. Therefore, the risk of cracks in the protective film 116 increases. Further, when the protective film 116 has a tensile stress, if the display device is bent in the direction opposite to that in the case of FIG. 4, the protective film 116 is bent against the tensile stress of the protective film 116. Therefore, the risk of cracks in the protective film 116 increases.

Since the stress of the protective film (moisture protective film) affects the bending resistance of the protective film, if only the film formed by the plasma CVD method is used as the protective film 116 as shown in FIG. 19, the protective film is used. Due to the stress of 116, the bending resistance of the protective film 116 becomes low, and there is a concern that the protective film 116 may crack due to bending.

That is, when a material suitable for the protective film 116 (for example, silicon nitride) is selected and the protective film 116 is formed at a temperature (preferably 100 ° C. or lower) that does not adversely affect the organic EL element, a large stress is applied to the protective film 116. (Large compressive stress when the protective film 116 is a silicon nitride film) is generated, and the bending resistance of the protective film 116 may decrease due to the stress. That is, since the protective film 116 of the first study example shown in FIG. 19 is entirely composed of a film formed by using the plasma CVD method, the stress of the film formed by using the plasma CVD method is increased. The bending resistance of the protective film 116 is greatly affected, and the bending resistance of the protective film 116 is lowered.

On the other hand, in the plasma ALD method, it is relatively easy to control the stress of the film to be formed, and the stress of the film to be formed can be controlled in a desired size and direction by adjusting the film forming conditions. For example, as described with reference to FIG. 22 described later, by controlling the high frequency power for generating plasma (high frequency power applied to the upper electrode 42), the stress of the film formed by the plasma ALD method can be increased. Can be controlled.

Therefore, in the present embodiment, as shown in FIG. 18, the protective film 16 includes an insulating film 16a formed by the plasma ALD method and an insulating film 16b formed on the insulating film 16a by the plasma CVD method. , It has a laminated structure with an insulating film 16c formed on the insulating film 16b by the plasma ALD method. That is, the protective film 16 has a structure in which the insulating film 16b formed by the plasma CVD method is sandwiched between the insulating film 16c formed by the plasma ALD method and the insulating film 16a formed by the plasma ALD method. .. As a result, the stress of the insulating film 16b formed by the plasma CVD method can be relaxed (offset) by the insulating film 16c formed by the plasma ALD method and the insulating film 16a formed by the plasma ALD method. It is possible to suppress or prevent a decrease in the bending resistance of the protective film 16 due to the stress of the protective film 16, and it is possible to suppress or prevent cracks in the protective film 16 due to bending.

That is, also in the protective film 16 of the present embodiment, the stress tends to increase, reflecting that the insulating film 16b is formed by using the plasma CVD method. In particular, the insulating film 16b is formed by the plasma CVD method. In the case of the silicon nitride film formed in the above, the insulating film 16b becomes a film having a large compressive stress. However, the insulating films 16a and 16c are formed by using the plasma ALD method in which the stress of the formed film is relatively easy to control, and the insulating films 16b are sandwiched between the insulating films 16a and 16c. The stress of the formed insulating film 16b can be relaxed (offset) by the insulating film 16c formed by the plasma ALD method and the insulating film 16a formed by the plasma ALD method.

That is, by adopting the plasma ALD method in which the film stress can be easily controlled as the film forming method of the insulating films 16a and 16c, the stress of the insulating film 16b formed by the plasma CVD method is relaxed by the stress of the insulating films 16a and 16c ( The stress of the insulating film 16a can be controlled when the insulating film 16a is formed, and the stress of the insulating film 16c can be controlled when the insulating film 16c is formed.

Specifically, when the stress of the insulating film 16b formed in step S6b is compressive stress, the insulating film 16a having tensile stress is formed by the plasma ALD method in step S6a, and the tensile stress is formed in step S6c. The insulating film 16c having the above is formed by the plasma ALD method. As a result, in the formed protective film 16, the direction of stress of the insulating film 16b (here, compressive stress) and the direction of stress of the insulating films 16a and 16c sandwiching the insulating film 16b (here, tensile stress) are mutually different. Since the directions are opposite, the stress of the insulating film 16b (here, compressive stress) can be relaxed (offset) by the stress of the insulating film 16c and the insulating film 16a (here, tensile stress).

On the other hand, when the stress of the insulating film 16b formed in step S6b is tensile stress, the insulating film 16a having compressive stress is formed by the plasma ALD method in step S6a, and the insulating film 16a having compressive stress is formed in step S6c. The film 16c is formed by the plasma ALD method. As a result, in the formed protective film 16, the direction of stress of the insulating film 16b (here, tensile stress) and the direction of stress of the insulating films 16a and 16c sandwiching the insulating film 16b (here, compressive stress) are mutually different. Since the directions are opposite, the stress of the insulating film 16b (here, tensile stress) can be relaxed (offset) by the stress of the insulating film 16c and the insulating film 16a (here, compressive stress).

As described above, the silicon nitride film formed by the plasma CVD method at a temperature (preferably 100 ° C. or lower) that does not adversely affect the organic EL element becomes a film having a considerably large compressive stress. Therefore, when a silicon nitride film is used as the insulating film 16b formed by the plasma CVD method, the insulating film 16b is a film having a considerably large compressive stress. In this case, the insulating films 16a and 16c formed by the plasma ALD method may be films having tensile stress. As a result, the stress of the insulating film 16b (here, compressive stress) can be relaxed (offset) by the stress between the insulating film 16c and the insulating film 16a (here, tensile stress).

As described above, in the present embodiment, the insulating film 16b formed by the plasma CVD method is sandwiched between the insulating films 16a and 16c formed by the plasma ALD method, whereby the insulating film formed by the plasma CVD method is adopted. The stress of 16b can be relaxed (offset) by the stress of the insulating films 16a and 16c formed by the plasma ALD method. Specifically, the insulating films 16a and 16c are formed in steps S6a and S6c so that each of the insulating film 16a and the insulating film 16c has a stress in the direction opposite to the stress direction of the insulating film 16b. As a result, in the formed protective film 16, the stress of the insulating films 16a and 16c sandwiching the insulating film 16b is in the opposite direction to the stress of the insulating film 16b, so that the stress of the insulating film 16b is changed to the insulating film 16c and the insulating film. It can be relaxed (offset) by the stress of 16a.

The protective film 216 of the second study example of FIG. 20 has a laminated structure composed of an insulating film 216b formed by the plasma CVD method and an insulating film 216c formed on the insulating film 216b by the plasma ALD method. Under the insulating film 216b formed by the plasma CVD method, the insulating film formed by the plasma ALD method (the film corresponding to the insulating film 16a of the present embodiment) is not formed. Further, the protective film 316 of the third study example of FIG. 21 has a laminated structure composed of an insulating film 316a formed by the plasma ALD method and an insulating film 316b formed on the insulating film 316a by the plasma CVD method. However, the insulating film formed by the plasma ALD method (the film corresponding to the insulating film 16c of the present embodiment) is not formed on the insulating film 316b formed by the plasma CVD method. Therefore, in the protective film 216 of the second study example of FIG. 20 and the protective film 316 of the third study example of FIG. 21, the protective film (216, 316) is a plasma ALD of an insulating film formed by the plasma CVD method. The structure is not sandwiched between insulating films formed by the method. Therefore, in the protective film 216 of the second study example of FIG. 20 and the protective film 316 of the third study example of FIG. 21, the stress of the insulating films (216b, 316b) formed by the plasma CVD method is formed by the plasma ALD method. It is difficult to sufficiently relax (cancel) the stress of the insulating film (216c, 316a).

That is, in the protective film 216 of the second study example of FIG. 20, the insulating film 216b formed by the plasma CVD method is a film having compressive stress, and the insulating film 216c formed on the insulating film 216b by the plasma ALD method is formed. It is assumed that the film has tensile stress. In this case, the stress (compressive stress) of the upper layer portion of the insulating film 216b can be relaxed (cancelled) by the stress (tensile stress) of the insulating film 216c on the insulating film 216b, but the stress (compressive stress) of the lower layer portion of the insulating film 216b. ) Is difficult to relax (cancel) by the stress (tensile stress) of the insulating film 216c on the insulating film 216b. Therefore, in the protective film 216 of the second study example of FIG. 20, even if the insulating film 216c formed by the plasma ALD method is arranged on the insulating film 216b formed by the plasma CVD method, the stress of the protective film 216 is applied. As a result, the effect of suppressing the bending resistance of the protective film 216 from being lowered is limited, and there is a concern that the protective film 216 may crack due to bending.

Further, in the protective film 316 of the third study example of FIG. 21, the insulating film 316b formed by the plasma CVD method is a film having compressive stress, and the insulating film 316a formed by the plasma ALD method under the insulating film 316b. Is a film with tensile stress. In this case, the stress (compressive stress) of the lower layer portion of the insulating film 316b can be relaxed (cancelled) by the stress (tensile stress) of the insulating film 316a under the insulating film 316b, but the stress (compression) of the upper layer portion of the insulating film 316b. It is difficult to relax (cancel) the stress) by the stress (tensile stress) of the insulating film 316a under the insulating film 316b. Therefore, in the protective film 316 of the third study example of FIG. 21, even if the insulating film 316a formed by the plasma ALD method is arranged under the insulating film 316b formed by the plasma CVD method, the stress of the protective film 316 is reached. The effect of suppressing the bending resistance of the protective film 316 from being lowered due to the above is limited, and there is a concern that the protective film 316 may be cracked due to bending.

On the other hand, in the present embodiment, the protective film 16 has a structure in which the insulating film 16b formed by the plasma CVD method is sandwiched between the insulating films 16a and 16b formed by the plasma ALD method. Here, it is assumed that the insulating film 16b formed by the plasma CVD method is a film having compressive stress, and the insulating films 16a and 16c formed by the plasma ALD method are films having tensile stress. In this case, the stress (compressive stress) of the lower layer portion of the insulating film 16b can be relaxed (cancelled) by the stress (tensile stress) of the insulating film 16a under the insulating film 16b, and the stress of the upper layer portion of the insulating film 16b (compressive stress). ) Can be relaxed (offset) by the stress (tensile stress) of the insulating film 16c on the insulating film 16b. Therefore, the stress (compressive stress) in the entire insulating film 16b can be relaxed (offset) by the stresses of the insulating film 16a and the insulating film 16b. Therefore, in the present embodiment, by sandwiching the insulating film 16b formed by the plasma CVD method between the insulating films 16a and 16b formed by the plasma ALD method, the bending resistance of the protective film 116 is increased due to the stress of the protective film 16. It is possible to accurately suppress or prevent the lowering, and it is possible to accurately suppress or prevent cracks in the protective film 16 due to bending.

Further, in the case of the protective film 216 of the second study example of FIG. 20 and the case of the protective film 316 of the third study example of FIG. 21, one side of the upper surface side and the lower surface side of the plasma CVD film (216b, 316b). Since the plasma ALD film is formed only on the plasma ALD film, it is necessary to increase the thickness of the plasma ALD film (216c, 316a) in order to enhance the action of relaxing the stress of the plasma CVD film (216b, 316b). However, increasing the thickness of the plasma ALD film leads to increasing the thickness of the entire protective film including the plasma ALD film and the plasma CVD film, but increasing the thickness of the protective film protects the film. The bending resistance of the film is lowered, which leads to easy cracking of the protective film due to bending. The film (insulating film) formed by using the plasma ALD method is referred to as a plasma ALD film, and the film (insulating film) formed by using the plasma CVD method is referred to as a plasma CVD film. The insulating film 16a, the insulating film 16c, the insulating film 216c and the insulating film 316a can all be regarded as a plasma ALD film, and the insulating film 16b, the protective film 116, the insulating film 216b and the insulating film 316b are all plasma CVD films. Can be regarded as.

Increasing the thickness of the protective film regardless of the presence or absence of stress in the protective film leads to the tendency for cracks in the protective film to occur due to bending. In order to improve the bending resistance of the protective film, it is effective to reduce the thickness of the protective film, and if the thickness of the protective film is reduced, cracks in the protective film due to bending are less likely to occur. Therefore, in the case of the protective film 216 of the second study example of FIG. 20 and the case of the protective film 316 of the third study example of FIG. 21, the action of relaxing the stress of the insulating films (216b, 316b) formed by the plasma CVD method. It is not a good idea to increase the thickness of the plasma ALD film (216c, 316a) in order to improve the bending resistance of the protective film.

On the other hand, in the case of the protective film 16 of the present embodiment, the plasma ALD film (16a, 16c) is formed on both the upper surface side and the lower surface side of the insulating film 16b formed by the plasma CVD method. Even if the thickness of the ALD film (16a, 16c) is not increased, the effect of relaxing the stress of the insulating film 16b formed by the plasma CVD method can be enhanced. Therefore, the action of relaxing the stress of the insulating films 16b formed by the plasma CVD method can be efficiently obtained without increasing the thickness of the insulating films 16a and 16c formed by the plasma ALD method. That is, the stress of the entire protective film 16 can be relaxed while suppressing the thickness of the entire protective film 16. Therefore, in the case of the protective film 16 of the present embodiment, the stress of the insulating film 16b formed by the plasma CVD method is relaxed by the stress of the plasma ALD films (16a, 16c) sandwiching the insulating film 16b. The bending resistance of the protective film 16 can be improved in that the relaxing action can be efficiently obtained without increasing the thickness of the plasma ALD film (16a, 16c). In the present embodiment, by adopting a structure in which the insulating film 16b formed by the plasma CVD method is sandwiched between the insulating films 16a and 16c formed by the plasma ALD method, the stress of the entire protective film 16 is controlled to control the protective film. The bending resistance of the protective film 16 can be improved, and the bending resistance of the protective film 16 can be improved by suppressing the thickness of the entire protective film 16. Therefore, it is possible to suppress or prevent cracks in the protective film 16 during bending. Therefore, the reliability of the protective film 16 can be improved, and by extension, the reliability of the display device can be improved.

Further, the insulating film 16a and the insulating film 16c are provided to relax (cancel) the stress of the insulating film 16b. Therefore, the magnitude of the stress (total stress) in the entire protective film 16 is smaller than the magnitude of the stress in the insulating film 16b. That is, the protective film is formed by the laminated film of the insulating films 16a, 16b, 16c rather than the protective film formed by the independent insulating film 16b without forming the insulating films 16a, 16c. The stress (absolute value) of is small. Therefore, each of the insulating films 16a and 16c needs to have a stress in the direction opposite to the stress direction of the insulating film 16b. By sandwiching the stressed insulating film 16b between the insulating films 16a and 16c having a stress in the direction opposite to the stress of the insulating film 16b, the stress of the insulating film 16b is relaxed (cancelled) and the insulating films 16a and 16c are formed. The magnitude of the stress of the protective film 16 can be reduced as compared with the case where the protective film 16 is not used, and the bending resistance of the protective film 16 can be improved. Therefore, it is possible to suppress or prevent cracks in the protective film 16 during bending. Therefore, the reliability of the protective film 16 can be improved, and by extension, the reliability of the display device can be improved.

For example, when the protective film is formed by a single insulating film 16b without forming the insulating films 16a and 16c, the stress magnitude (absolute value) of the entire protective film is about 300 to 400 MPa, but the insulating film is insulated. In the protective film having a structure in which the films 16b are sandwiched between the insulating films 16a and 16b, the overall stress magnitude (absolute value) can be about 100 MPa or less (that is, -100 MPa to 100 MPa).

Further, in the protective film 16 of the present embodiment, the insulating film 16c is formed on the insulating film 16b formed by the plasma CVD method by the plasma ALD method so as to be in contact with the insulating film 16b. As a result, even if a pinhole is generated in the insulating film 16b due to the formation of the insulating film 16b by the plasma CVD method, the pinhole can be filled by forming the insulating film 16c by the plasma ALD method. The effect is also obtained. This will be specifically described.

The film formed by the plasma CVD method may have defects such as pinholes (micropores) formed during film formation. Therefore, reflecting that the insulating film 16b is formed by the plasma CVD method, there is a possibility that pinholes may occur in the insulating film 16b when the insulating film 16b is formed. If a pinhole is formed in the insulating film 16b, there is a concern that moisture may invade the organic EL element side via the pinhole.

On the other hand, in the present embodiment, the insulating film 16c is formed by the plasma ALD method on the insulating film 16b formed by the plasma CVD method. Since the plasma ALD method is a film forming method having high coverage for steps and holes, even if a pinhole is formed in the insulating film 16b when the insulating film 16b is formed by the plasma CVD method, the insulating film is formed. If the insulating film 16c is formed on the 16b by the plasma ALD method, the pinhole of the insulating film 16b can be filled with the insulating film 16c. This makes it possible to prevent water from being transmitted to the organic EL element via the pinhole of the insulating film 16b. Therefore, the function of preventing (shielding) the transmission of water from the protective film 16 can be enhanced, and the effect of preventing the transmission of water to the organic EL element by the protective film 16 can be enhanced. Therefore, the reliability of the protective film 16 can be improved. Therefore, the reliability of the organic EL element can be improved, and the reliability of the display device (organic EL display device) using the organic EL element can be improved.

Further, each of the insulating film 16a and the insulating film 16c has a stress in the direction opposite to the stress direction of the insulating film 16b, but the magnitude (absolute value) of the respective stresses of the insulating film 16a and the insulating film 16c. ) Is preferably smaller than the magnitude (absolute value) of the stress of the insulating film 16b. This is because the insulating film 16a and the insulating film 16c are provided to relax (cancel) the stress of the insulating film 16b, but if the stress of the insulating film 16a and the insulating film 16c becomes too large, the insulating film 16a and the insulating film 16c are provided. This is because there is a concern that a large stress of 16c will lead to cracks in the protective film. Therefore, the magnitude of the stress of the insulating films 16a and 16c is preferably smaller than the magnitude of the stress of the insulating films 16b, whereby the stress of the insulating films 16a and 16c is relaxed (offset) by the insulating films 16a and 16c. The bending resistance of the protective film 16 can be improved, and the risk that the stress of the insulating films 16a and 16c reduces the bending resistance of the protective film 16 can be suppressed or avoided. Therefore, the stress of the entire protective film 16 can be accurately controlled, and the bending resistance of the entire protective film 16 can be accurately improved.

Further, the insulating film 16a and the insulating film 16c have the same stress direction, but the stress magnitude (absolute value) of the insulating film 16a and the stress magnitude (absolute value) of the insulating film 16c are about the same. If so, it is more preferable. By doing so, the action of relaxing (canceling) the stress of the insulating film 16b by the insulating film 16a and the action of relaxing (canceling) the stress of the insulating film 16b by the insulating film 16c can be made comparable. The stress balance in the protective film 16 is improved, and the effect of improving the bending resistance of the protective film 16 can be further enhanced.

Further, it is more preferable that the insulating film 16a and the insulating film 16c are made of the same material. The type of the raw material gas used in the first step is common (same) in step S6a and step S6c, and the type of reaction gas used in the third step is common (same) in step S6a and step S6c (step S6a and step S6c). If it is the same), the insulating film 16a and the insulating film 16c are formed of the same material because the constituent elements are the same as each other.

If the insulating film 16a and the insulating film 16c are made of the same material, the magnitude of the stress of the insulating film 16a and the magnitude of the stress of the insulating film 16c can be easily made to be the same. Therefore, the action of relaxing (canceling) the stress of the insulating film 16b by the insulating film 16a and the action of relaxing (canceling) the stress of the insulating film 16b by the insulating film 16c can be easily made to the same extent, so that the protective film 16 The balance of stress is improved, and the effect of improving the bending resistance of the protective film 16 can be further enhanced.

Further, it is more preferable that the insulating film 16a and the insulating film 16c are formed under the same film forming conditions. The film forming conditions include, for example, the type and flow rate of the raw material gas used in the first step, the type and flow rate of the reaction gas used in the third step, the magnitude and frequency of the high frequency power in the third step, and the substrate temperature ( Film formation temperature) and so on. If the insulating film 16a and the insulating film 16c are formed under the same film forming conditions, the stress directions of the insulating film 16a and the insulating film 16c are the same, and the magnitude (absolute value) of the stress is about the same. be able to. As a result, the action of relaxing (canceling) the stress of the insulating film 16b by the insulating film 16a and the action of relaxing (canceling) the stress of the insulating film 16b by the insulating film 16c can be made to the same extent, thus protecting the insulating film 16b. The balance of stress in the film 16 is improved, and the effect of improving the bending resistance of the protective film 16 can be further enhanced.

Other features of this embodiment will be further described.

In the present embodiment, the protective film 16 is a laminated film of the insulating film 16a, the insulating film 16b, and the insulating film 16c, and the thicknesses of the insulating films 16a, 16b, and 16c are also devised. Hereinafter, a specific description will be given.

Increasing the thickness of the protective film regardless of the presence or absence of stress in the protective film leads to the tendency for cracks in the protective film to occur due to bending. In order to improve the bending resistance of the protective film, it is effective to reduce the thickness of the protective film, and if the thickness of the protective film is reduced, cracks in the protective film due to bending are less likely to occur.

Therefore, it is desirable to suppress the thickness of the protective film 16 also in the present embodiment, but even if the thickness of the protective film 16 is suppressed, the effect of preventing the invasion of water by the protective film 16 can be ensured. Must be done.

Therefore, in the present embodiment, the protective film 16 is formed of a laminated film of the insulating films 16a, 16b, 16c, and the thickness (film thickness) T2 of the insulating film 16b is changed to the thickness (film thickness) of the insulating film 16a. ) It is preferable to make it larger than the total of T1 and the thickness (thickness) T3 of the insulating film 16c (that is, T2> T1 + T3). The thickness T1 of the insulating film 16a is shown in FIGS. 3, 10 and 18, and the thickness T2 of the insulating film 16b is shown in FIGS. 3, 11 and 18 of the insulating film 16c. The thickness T3 is shown in FIGS. 3, 12 and 18, and the thickness (thickness) T4 of the protective film 16 is shown in FIGS. 3, 12 and 18. As a result, even if the thickness of the protective film 16 is suppressed, the effect of preventing the intrusion of water by the protective film 16 can be efficiently ensured. The reason will be explained below.

That is, the insulating film 16b formed by the plasma CVD method has a higher barrier property to moisture than the insulating films 16a and 16c formed by the plasma ALD method, and the transmittance of moisture per unit thickness is lower. Conversely, the insulating films 16a and 16c formed by the plasma ALD method have a lower barrier property to moisture and a higher transmittance of moisture per unit thickness than the insulating films 16b formed by the plasma CVD method. .. Therefore, of the thickness T4 of the protective film 16, increasing the thickness distributed to the insulating films 16b rather than increasing the thickness distributed to the insulating films 16a and 16c is a barrier against moisture in the protective film 16. It is advantageous in enhancing the sex.

Therefore, in the present embodiment, the thickness (T2) of the insulating film 16b having a high barrier property against moisture is made larger than the total thickness (T1 + T3) of the insulating films 16a and 16c having a low barrier property against moisture. (That is, T2> T1 + T3). As a result, of the thickness T4 of the protective film 16, the thickness allocated to the insulating film 16b having a high barrier property to moisture is relatively larger than the thickness allocated to the insulating films 16a and 16c having a low barrier property to moisture. Therefore, the barrier property of the protective film 16 against moisture can be efficiently enhanced.

That is, among the insulating films 16a, 16b, and 16c, by thickening the insulating film 16b having a low water transmittance per unit thickness, the effect of preventing the intrusion of water by the protective film 16 can be enhanced, and the insulating film 16a, 16b, and 16c can be insulated. With respect to the insulating films 16a and 16c having a higher water transmittance per unit thickness than the film 16b, the thickness of the entire protective film 16 can be suppressed by reducing the thickness. Thereby, the effect of preventing the invasion of water by the protective film 16 can be efficiently obtained while suppressing the thickness of the protective film 16. Therefore, while obtaining the effect of improving the bending resistance of the protective film 16 by suppressing the thickness of the protective film 16, the effect of preventing the intrusion of moisture by the protective film 16 even if the thickness of the protective film 16 is suppressed. Can be secured efficiently.

It should be noted that making the thickness T2 of the insulating film 16b larger than the sum of the thickness T1 of the insulating film 16a and the thickness T3 of the insulating film 16c (that is, T2> T1 + T3) is the thickness of the protective film 16. It corresponds to allocating more than half (50%) of T4 to the thickness T2 of the insulating film 16b (that is, T2> T4 × 1/2). That is, to make the thickness T2 of the insulating film 16b larger than the sum of the thickness T1 of the insulating film 16a and the thickness T3 of the insulating film 16c, the thickness T2 of the insulating film 16b is changed to the thickness of the protective film 16. It corresponds to making it larger than half (50%) of T4. This is because the protective film 16 is composed of a laminated film of the insulating films 16a, 16b, 16c, so that the thickness T4 of the protective film 16 is the thickness T1 of the insulating film 16a, the thickness T2 of the insulating film 16b, and the insulating film 16c. This is because it is substantially the same as the sum of the thickness T3 (that is, T4 = T1 + T2 + T3), and therefore the relationship of T2> T1 + T3 and the relationship of T2> T4 × 1/2 are substantially equivalent.

In the present embodiment, more than half (50%) of the thickness T4 of the protective film 16 is allocated to the thickness T2 of the insulating film 16b, and the protective film 16 is mainly used as the insulating film 16b having a high barrier property against moisture. The effect of preventing the invasion of water by the protective film 16 can be efficiently obtained by the configuration of the above.

Further, among the insulating films 16a, 16b, 16c constituting the protective film 16, the insulating film 16b is mainly responsible for preventing the intrusion of water, so that the effect of preventing the invasion of water by the protective film 16 is enhanced. Therefore, it is effective to increase the thickness T2 of the insulating film 16b to some extent. From this viewpoint, the thickness T2 of the insulating film 16b formed in step S16b is preferably larger than 20 nm (that is, T2> 20 nm). As a result, the thickness T2 of the insulating film 16b having a high barrier property against moisture can be secured, and the effect of preventing the invasion of moisture by the protective film 16 can be accurately obtained.

In the present embodiment, the thickness of the insulating films 16a and 16c is thinner than that of the insulating film 16b, but the plasma ALD film is not arranged only on one of the upper surface side and the lower surface side of the insulating film 16b. , The plasma ALD film is arranged on both the upper surface side and the lower surface side of the insulating film 16b, and the insulating film 16b is sandwiched between the insulating film 16a formed by the plasma ALD method and the insulating film 16c formed by the plasma ALD method. The structure is adopted. Therefore, the action of relaxing the stress of the insulating films 16b can be efficiently obtained without increasing the thickness of the insulating films 16a and 16c. Therefore, in the present embodiment, even if the total thickness of the insulating films 16a and 16c is smaller than the thickness T2 of the insulating film 16b (that is, T2> T1 + T3), the insulating films 16a and 16c make the insulating film 16b. The action of relieving stress can be efficiently obtained. Therefore, in the present embodiment, the effect of improving the bending resistance of the protective film 16 by controlling the stress of the protective film 16 and the bending resistance of the protective film 16 by suppressing the thickness of the protective film 16 are improved. While obtaining the effect, even if the thickness of the protective film 16 is suppressed, the effect of preventing the invasion of water by the protective film 16 can be efficiently ensured.

Further, as described above, the insulating film 16c also has an action of filling the pinholes formed in the insulating film 16b. However, if the thickness T3 of the insulating film 16c is too thin, the pinholes formed in the insulating film 16b may not be sufficiently filled with the insulating film 16c. Therefore, the thickness T3 of the insulating film 16c formed in step S6c is preferably 10 nm or more (T3 ≧ 10 nm), and more preferably 15 nm or more (T3 ≧ 15 nm). By doing so, even if a pinhole is generated in the insulating film 16b when the insulating film 16b is formed by the plasma CVD method in step S6b, when the insulating film 16c is formed by the plasma ALD method in step S6c, the insulating film is formed. The pinhole of 16b can be accurately embedded with the insulating film 16c. Thereby, the effect of preventing the invasion of water by the protective film 16 can be obtained more accurately.

Further, the thickness T1 of the insulating film 16a is preferably the same as the thickness T3 of the insulating film 16c (that is, T1 = T3). The reason is as follows.

That is, in the present embodiment, a structure in which the insulating film 16b is sandwiched between the insulating film 16a formed by the plasma ALD method and the insulating film 16c formed by the plasma ALD method is adopted, and the insulating film 16a and the insulating film 16c are adopted. All of them have an action of relaxing (cancelling) the stress of the insulating film 16b. If the thickness T1 of the insulating film 16a and the thickness T3 of the insulating film 16c are the same, the action of relaxing (canceling) the stress of the insulating film 16b by the insulating film 16a and the stress of the insulating film 16b are reduced by the insulating film 16c. Since the action of relaxing (offset) is substantially the same, the stress balance in the protective film 16 is improved, and the effect of improving the bending resistance of the protective film 16 can be further enhanced. Therefore, it is more preferable if the thickness T1 of the insulating film 16a and the thickness T3 of the insulating film 16c are the same (that is, T1 = T3). Therefore, the thickness T1 of the insulating film 16a is also preferably 10 nm or more (T3 ≧ 10 nm), reflecting that the thickness T3 of the insulating film 16c is preferably 10 nm or more (T3 ≧ 10 nm).

Further, in the present embodiment, the protective film is improved in bending resistance by adopting a structure in which the insulating film 16b is sandwiched between the insulating film 16a and the insulating film 16c formed by the plasma ALD method. Even if 16 is made thicker, cracks are less likely to occur in the protective film 16 at the time of bending. However, increasing the thickness of the protective film acts to increase the risk of cracks in the protective film during bending. Therefore, the thickness T4 of the protective film 16 is more preferably 200 nm or less (that is, T4 ≦ 200 nm). As a result, even when the flexible substrate (display device) is bent with a small bending radius, it is possible to more accurately prevent cracks from occurring in the protective film 16. The fact that the thickness T4 of the protective film 16 is 200 nm or less means that the total of the thickness T1 of the insulating film 16a, the thickness T2 of the insulating film 16b, and the thickness T3 of the insulating film 16c is 200 nm or less (that is, T1 + T2 + T3 ≦ 200 nm). ) Corresponds to.

Further, among the insulating films 16a, 16b, 16c constituting the protective film 16, the insulating film 16b is mainly responsible for preventing the intrusion of water, so that the effect of preventing the invasion of water by the protective film 16 is enhanced. Therefore, it is effective to increase the density of the insulating film 16b. If the density of the insulating film 16b is increased, the barrier property of the insulating film 16b against moisture can be further enhanced. Therefore, when the insulating film 16b is formed by the plasma CVD method in step S6b, it is more preferable to use the ICP-CVD method. Compared with the CCP (Conductively Coupled Plasma) -CVD method (capacitive coupled plasma CVD method), the ICP-CVD method tends to increase the plasma density (plasma electron density), and the film formed while suppressing the film formation temperature. Easy to increase density. By using the ICP-CVD method in the process of forming the insulating film 16b, the density of the insulating film 16b can be increased while suppressing the film formation temperature, and the effect of preventing the intrusion of moisture by the protective film 16 can be further enhanced. it can. Therefore, the effect of preventing the invasion of water by the protective film 16 can be further enhanced while suppressing the thickness of the protective film 16.

<About the forming process of the insulating film 16a and the insulating film 16c>
As described above, in the protective film 16 composed of the laminated film of the insulating films 16a, 16b, 16c, the insulating film 16a and the insulating film 16c are films having a stress in the direction opposite to the stress of the insulating film 16b. Both the insulating film 16a and the insulating film 16c are formed by using the plasma ALD method, and a method of controlling the stress of the insulating film 16a and the insulating film 16c by the plasma ALD method will be described below.

The ALD method (plasma ALD method) includes a first step (raw material gas supply step), a second step (purge step), and a third step (reaction gas supply step) as described in the above section "About the film forming apparatus". ) And the fourth step (purge step) are set as one cycle, and this is repeated for a plurality of cycles to form a desired film on the surface of the object to be treated 27. When the plasma ALD method is used as the ALD method, the reaction gas is turned into plasma in the third step. Both the insulating film 16a and the insulating film 16c are formed by repeating the first step, the second step, the third step, and the fourth step for a plurality of cycles. However, an insulating film 16b forming step (plasma CVD step) of step S6b is performed between the insulating film 16a forming step (plasma ALD step) of step S6a and the insulating film 16c forming step (plasma ALD step) of step S6c. It is said. As described above, the first step is the step of supplying the raw material gas into the chamber (deposition container), the second step is the step of supplying the purge gas into the chamber, and the third step is the step of supplying the purge gas into the chamber. The fourth step is a step of supplying purge gas into the chamber. This chamber corresponds to the chamber 24 in step S6a and corresponds to the chamber 26 in step S6c.

In the present embodiment, the insulating film 16a and the insulating film 16c are formed by using a plasma ALD apparatus (plasma ALD method), and in each of step S6a and step S6c, in the third step (reaction gas supply step), the insulating film 16a and the insulating film 16c are formed. , The reaction gas is turned into plasma by high frequency power. The method of controlling the stress of each of the insulating films 16a and 16c is a method of controlling the stress of the insulating film to be formed by controlling the magnitude of the high-frequency power in the third step. To explain.

In the film forming step using the plasma ALD device, the density of the formed film is the high frequency power (here, the high frequency applied to the upper electrode 42) for converting the reaction gas into plasma in the third step (reaction gas supply step). It can be controlled by the magnitude of power). Specifically, when the high frequency power of the third step is increased, the density of the formed film tends to be high, and when the high frequency power of the third step is decreased, the density of the formed film tends to be low. When the high-frequency power of the third step is increased to a certain extent or more, the formed film has few defects (pores) and becomes close to the film (layer) having an ideal crystal structure, so that the density of the formed film becomes high. , Becomes almost constant. The high-frequency power for converting the reaction gas into plasma in the third step (here, the high-frequency power applied to the upper electrode 42) is referred to as "high-frequency power in the third step" or "high-frequency power in the third step". It will be referred to.

That is, in the third step, the reaction gas introduced into the chambers (24, 26) is reacted with the raw material gas molecules adsorbed on the surface of the object to be treated 27, but the reactivity (reaction activity) of the reaction gas is increased. In order to enhance the reaction gas, the reaction gas is converted into plasma and reacted with the raw material gas molecules adsorbed on the surface of the object to be treated 27, thereby forming an atomic layer as a reaction layer on the surface of the object to be treated 27. When the high-frequency power in the third step is increased, the reactivity between the generated plasma (active species) and the raw material gas molecules adsorbed on the surface of the object to be treated 27 becomes high. Therefore, when the first step, the second step, the third step, and the fourth step are repeated for a plurality of cycles under the condition that the high frequency power of the third step is increased, the produced film has few defects (pores). It becomes a high-density film close to a film (layer) with an ideal crystal structure. On the other hand, when the high-frequency power in the third step is reduced, the reactivity between the generated plasma (active species) and the raw material gas molecules adsorbed on the surface of the object to be treated 27 becomes low. Therefore, when the first step, the second step, the third step, and the fourth step are repeated for a plurality of cycles under the condition that the high frequency power of the third step is reduced, the produced film has many defects (pores). The density of the film is lower than that of the film (layer) having an ideal crystal structure.

Therefore, in the plasma ALD method, a high-density film can be formed by increasing the high-frequency power in the third step, and a low-density film can be formed by decreasing the high-frequency power in the third step. Therefore, the density of the formed film can be controlled by controlling the high frequency power of the third step.

A film formed by the plasma ALD method is related to the density (denseness) of the film and the stress of the film. FIG. 22 is a graph showing the results of examining the correlation between the density and stress of the film (here, the aluminum oxide film) formed by the plasma ALD method. The horizontal axis of the graph of FIG. 22 corresponds to the density (film density) of the aluminum oxide film formed by the plasma ALD method, and the vertical axis of the graph of FIG. 22 corresponds to the stress of the aluminum oxide film formed by the plasma ALD method. Corresponds to (membrane stress). In addition, on the vertical axis of FIG. 22, tensile stress is shown as plus and compressive stress is shown as minus. Therefore, for example, 300 MPa and −300 MPa have the same stress magnitude, but the stress directions are opposite to each other, 300 MPa is tensile stress, and −300 MPa is compressive stress.

In the graph of FIG. 22, the correlation between the density and the stress is examined and plotted for the four aluminum oxide films formed by the plasma ALD method by changing the high frequency power in the third step. That is, the aluminum oxide film having a density of 2.85 g / cm ^3, and an aluminum oxide film having a density of 2.94 g / cm ^3, and an aluminum oxide film having a density of 3.02 g / cm ^3, density of 3.17 g / the aluminum oxide film of cm ^3, respectively formed by a plasma ALD method, is plotted the correlation between the density and stress which the aluminum oxide film in the graph of FIG. 22.

As described above, in the plasma ALD method, the density of the formed film can be controlled by controlling the high frequency power of the third step. Therefore, the density of the four aluminum oxide films plotted in the graph of FIG. 22 is also controlled by controlling the high-frequency power in the third step, and the high-density aluminum oxide film is the third. The low-density aluminum oxide film is formed under the condition that the high-frequency power of the step is increased, and is formed under the condition that the high-density power of the third step is decreased. Therefore, when comparing the high-frequency power of the third step with respect to the four aluminum oxide films plotted in the graph of FIG. 22, the aluminum oxide film having a density of 3.17 g / cm ³ and the density of 3.02 g / cm ³ aluminum oxide film, an aluminum oxide film having a density of 2.94 g / cm ^3, a density in the order of the aluminum oxide film of 2.85 g / cm ^3, a high frequency power of the third step is smaller.

In the plasma ALD method, the density of the formed film can be controlled by controlling the high frequency power of the third step, and the stress of the formed film can be controlled accordingly.

For example, when the aluminum oxide film is formed by the plasma ALD method, as shown in the graph of FIG. 22, a high-density aluminum oxide film can be formed by increasing the high-frequency power of the third step. Along with this, the formed aluminum oxide film becomes a film having compressive stress. Then, if the high-frequency power of the third step is reduced, a low-density aluminum oxide film can be formed, and accordingly, the formed aluminum oxide film becomes a film having tensile stress.

That is, when the high-frequency power of the third step is sufficiently increased, the aluminum oxide film formed becomes a dense and high-density film, and accordingly becomes a film having compressive stress. Then, as the high-frequency power of the third step is reduced, the density of the formed aluminum oxide film gradually decreases, and the stress of the formed aluminum oxide film gradually increases in the magnitude of the compressive stress. It becomes smaller, and after the transition from compressive stress to tensile stress, the magnitude of tensile stress gradually increases.

Therefore, in step S6a, the insulating film 16a is formed by using the plasma ALD method, and the high-frequency power of the third step is controlled so that the direction and magnitude of the stress of the formed insulating film 16a can be set in a desired direction and. The size can be easily and accurately controlled. Similarly, in step S6c, the insulating film 16c is formed by using the plasma ALD method, and the high-frequency power of the third step is controlled so that the direction and magnitude of the stress of the formed insulating film 16c can be set in the desired direction and. The size can be easily and accurately controlled. Therefore, the insulating films 16a and 16c having a direction and a size capable of relaxing the stress of the insulating film 16b formed by the plasma CVD method can be easily and accurately formed by using the plasma ALD method.

In the present embodiment, by using the plasma ALD method as the film forming method of the insulating films 16a and 16c, it is possible to form a thin but strong stress film as the insulating films 16a and 16c. Therefore, even if the stress of the insulating film 16b becomes large, the stress of the insulating film 16b can be sufficiently relaxed by the stress of the insulating films 16a and 16b to improve the bending resistance of the protective film 16. For example, the insulating films 16b having a compressive stress of about −300 to −400 MPa can be sandwiched between the insulating films 16a and 16b having a tensile stress of about 100 to 250 MPa, respectively.

Further, by forming the insulating film 16a and the insulating film 16c with the same material and making the magnitude of the high frequency power of the third step the same in the steps S6a and S6c, the insulating film 16a and the insulating film 16c are formed. The direction of stress can be the same and the magnitude (absolute value) of stress can be made the same. As a result, the balance of stress in the protective film 16 is improved, and the effect of improving the bending resistance of the protective film 16 can be further enhanced.

FIG. 23 is a table showing the results of examining the number of cracks in the protective film after the bending test. In FIG. 23, a protective film formed on a flexible substrate is prepared, and then the flexible substrate is repeatedly bent many times with a small bending radius, and then the protective film is observed and per unit area of the protective film ( The result of checking the number of cracks (per 1 cm ^{2) is posted.}

The "single-layer structure protective film" shown in FIG. 23 is a protective film formed by a single layer of a silicon nitride film formed by a plasma CVD method, and is the structure of the protective film 116 of the first study example of FIG. 19 above. Corresponds to. The "three-layer structure protective film" shown in FIG. 23 is a protective film having a structure in which a silicon nitride film formed by a plasma CVD method is sandwiched between two aluminum oxide films formed by a plasma ALD method. It corresponds to the structure of the protective film 16 of the present embodiment of FIG. 18 above.

In the case of the "single-layer structure protective film" in FIG. 23, a compressive stress of about −250 MPa was generated in the protective film. On the other hand, in the case of the "three-layer structure protective film" in FIG. 23, a silicon nitride film (plasma CVD film) having a compressive stress of about -250 MPa is sandwiched between aluminum oxide films (plasma ALD film) having a tensile stress, and nitrided. By relaxing (cancelling) the compressive stress of the silicon film with the tensile stress of the aluminum oxide film sandwiching the silicon nitride film, a compressive stress of about -50 MPa was generated in the entire protective film. Then, when the protective film after the bending test was observed, in the case of the "single-layer structure protective film", about 1 × 10 ^{5 cracks per 1 cm 2} were observed in the protective film, but “three-layer structure protection” was observed. In the case of "membrane", about 2 × 10 ^{3 cracks per 1 cm 2} were observed in the protective film. It can be seen that the case of the "three-layer structure protective film" is less likely to cause cracks due to bending than the case of the "single-layer structure protective film", and the bending resistance of the protective film is higher.

In FIG. 23, the thickness of the protective film is intentionally increased to 500 nm in order to make it easier to compare the number of cracks generated due to bending between the “single-layer structure protective film” and the “three-layer structure protective film”. , The protective film is prone to cracks in the bending test. Therefore, in the case of the "three-layer structure protective film", 2 × 10 ^{3 cracks per 1 cm 2} were observed in the protective film having a thickness of 500 nm after the bending test, but the thickness of the protective film was 100 nm. Then, in the case of the "three-layer structure protective film", almost no cracks were observed after the bending test.

Therefore, it can be seen that the bending resistance of the protective film is improved by adopting the "three-layer structure protective film", and the bending resistance of the protective film is further improved by reducing the thickness of the protective film.

In the present embodiment, the protective film 16 has a structure in which the insulating film 16b formed by the plasma CVD method is sandwiched between the insulating films 16a and 16c formed by the plasma ALD method, as in the "three-layer structure protective film". However, since each of the insulating films 16a and 16c has a stress in the direction opposite to the stress direction of the insulating film 16b, the bending resistance of the protective film can be improved. If the thickness of the protective film 16 is reduced, the bending resistance of the protective film 16 can be further improved. However, as described above, the thicknesses of the insulating films 16a, 16b, and 16c constituting the protective film 16 are respectively. By devising the above, even if the thickness of the protective film 16 is reduced, the effect of preventing the invasion of moisture by the protective film 16 can be efficiently ensured. As a result, the overall reliability of the protective film 16 can be improved, and by extension, the reliability of the display device can be improved.

<Modification example>
FIG. 24 is a cross-sectional view (explanatory view) showing the cross-sectional structure of the protective film 16 of the modified example, and shows a cross section corresponding to FIG.

In the case of FIG. 24, the protective film 16 is formed on the insulating film 16a formed by the plasma ALD method, the insulating film 16b1 formed on the insulating film 16a by the plasma CVD method, and the insulating film 16b1 by the plasma ALD method. It has a laminated structure composed of the insulating film 16d formed, the insulating film 16b2 formed on the insulating film 16d by the plasma CVD method, and the insulating film 16c formed on the insulating film 16b2 by the plasma ALD method. .. In the protective film 16, the insulating film 16a is the lowest layer, the insulating film 16c is the uppermost layer, the insulating film 16b1 is in contact with the insulating film 16a, the insulating film 16d is in contact with the insulating film 16b1, and the insulating film 16b2 is in contact with the insulating film 16d. The insulating film 16c is in contact with the insulating film 16b2. The insulating films 16a, 16c and 16d can be regarded as plasma ALD films, respectively, and the insulating films 16b1 and 16b2 can be regarded as plasma CVD films, respectively.

The protective film 16 of FIG. 24 corresponds to the case where the plasma ALD film (16d) is inserted in the middle of the thickness of the plasma CVD film (16b) in the protective film 16 of FIG. That is, the protective film 16 of FIG. 24 replaces the insulating film 16b with the laminated film of the insulating film 16b1 and the insulating film 16d on the insulating film 16b1 and the insulating film 16b2 on the insulating film 16d in the protective film 16 of FIG. It corresponds to the case.

The protective film 16 of FIG. 24 has a step of forming the insulating film 16a by the plasma ALD method, a step of forming the insulating film 16b1 on the insulating film 16a by the plasma CVD method, and a plasma ALD of the insulating film 16d on the insulating film 16b1. It is formed by a step of forming by the method, a step of forming the insulating film 16b2 on the insulating film 16d by the plasma CVD method, and a step of forming the insulating film 16c on the insulating film 16b2 by the plasma ALD method.

As the insulating film 16d, an insulating film containing aluminum (Al) can be used as in the insulating films 16a and 16c. For example, an aluminum oxide film, an aluminum nitride film or an aluminum nitride film can be preferably used. However, among them, the aluminum oxide film is particularly preferable. As the insulating films 16b1 and 16b2, a silicon nitride film, a silicon oxide film or a silicon oxynitride film can be preferably used as in the case of the insulating film 16b, but a silicon nitride film is most preferable. The insulating film 16b1 and the insulating film 16b2 are preferably formed of the same material, and the insulating film 16a, the insulating film 16c, and the insulating film 16d are preferably formed of the same material.

In the protective film 16 of FIG. 24, both the insulating film 16b1 and the insulating film 16b2 are formed by the plasma CVD method, and the stress directions are the same. That is, when the insulating film 16b1 is a compressive stress film, the insulating film 16b2 is also a compressive stress film, and when the insulating film 16b1 is a tensile stress film, the insulating film 16b2 is also a tensile stress film. On the other hand, the insulating film 16a, the insulating film 16c, and the insulating film 16d are all formed by the plasma ALD method, and the stress direction is opposite to the stress direction of the insulating films 16b1 and 16b2. That is, when the insulating films 16b1, 16b2 are compressive stress films, each of the insulating films 16a, 16c, 16d is a tensile stress film, and when the insulating films 16b1, 16b2 are tensile stress films, the insulating films 16a, 16c, Each of 16d is a compressive stress film. Since the insulating films 16a, 16c, 16d are formed by the plasma ALD method, the stress can be easily controlled, and the insulating films 16a, 16c, 16d can be formed as a film having a stress in the direction opposite to the stress of the insulating films 16b1, 16b2. ..

In the case of the protective film 16 of FIG. 24, as the protective film 16, the insulating film 16b1 formed by the plasma CVD method is sandwiched between the insulating films 16a and 16d formed by the plasma ALD method, and the insulating film is formed by the plasma CVD method. The film 16b2 has a structure sandwiched between the insulating films 16d and 16c formed by the plasma ALD method. The insulating film 16a, the insulating film 16c, and the insulating film 16d each have a stress in the direction opposite to the stress direction of the insulating films 16b1 and 16b2. Therefore, the stress of the insulating film 16b1 formed by the plasma CVD method is relaxed (cancelled) by the stress of the insulating films 16a and 16d formed by the plasma ALD method, and the stress of the insulating film 16b2 formed by the plasma CVD method is relaxed. , It can be relaxed (offset) by the stress of the insulating films 16d and 16c formed by the plasma ALD method. As a result, it is possible to suppress or prevent the protective film 16 from being lowered in bending resistance due to the stress of the protective film 16, and it is possible to suppress or prevent cracks in the protective film 16 due to bending. ..

Here, the protective film 16 of FIG. 24 and the protective film 16 of FIG. 18 are compared. The protective film 16 of FIG. 18 has the following advantages as compared with the protective film 16 of FIG. 24.

That is, since the protective film 16 of FIG. 18 has a smaller number (number of layers) of insulating films constituting the protective film than the protective film 16 of FIG. 24, the number of steps required to form the protective film 16 is reduced. It can be reduced, the time required for forming the protective film 16 can be shortened, and the throughput can be improved.

Further, comparing the case of FIG. 18 and the case of FIG. 24, if the thickness of the protective film 16 is the same, the thickness of the plasma CVD film (16b) in the protective film 16 of FIG. 18 is larger than that of FIG. 24. It is larger than the total thickness of the plasma CVD film (16b1, 16b2) in the protective film 16 of the above. That is, the ratio of the thickness of the plasma CVD film to the thickness of the protective film 16 is likely to be larger in the case of FIG. 18 than in the case of FIG. 24. Therefore, from the viewpoint of increasing the moisture barrier property of the protective film 16 as much as possible, that is, reducing the moisture transmittance of the protective film 16 as much as possible, the thickness of the plasma CVD film having excellent moisture barrier property can be further increased. The case of FIG. 18 is more advantageous than the case of FIG. 24.

On the other hand, the protective film 16 of FIG. 24 has the following advantages as compared with the protective film 16 of FIG.

That is, since the protective film 16 of FIG. 24 can make the thickness of each plasma CVD film thinner than the protective film 16 of FIG. 18, the stress of the plasma CVD film is applied to the plasma sandwiching the plasma CVD film. The stress of the ALD film makes it easier to relax.

In the case of the protective film 16 of FIG. 24, the total of the thickness (thickness) T2a of the insulating film 16b1 and the thickness (film thickness) T2b of the insulating film 16b2 is the thickness (film thickness) T1 of the insulating film 16a. It is preferable that the thickness (thickness) T3 of the insulating film 16c and the thickness (thickness) T5 of the insulating film 16d are larger than the total (that is, T2a + T2b> T1 + T3 + T5). That is, also in the case of the protective film 16 of FIG. 24, it is preferable to allocate more than half (50%) of the thickness of the protective film 16 to the total thickness of the insulating films 16b1 and 16b2. The reason for doing so is that the insulating films 16b1, 16b2 have higher barrier properties against moisture than the insulating films 16a, 16c, 16d. Also in the case of FIG. 24, more than half (50%) of the thickness of the protective film 16 is distributed to the total thickness (T2a + T2b) of the insulating films 16b1 and 16b2, and the protective film 16 mainly has a barrier property against moisture. By forming the insulating films 16b1 and 16b2 having a high thickness, the effect of preventing the intrusion of moisture by the protective film 16 can be efficiently obtained.

Further, in the case of the protective film 16 of FIG. 24, the thickness T5 of the insulating film 16d is preferably 10 nm or more (T5 ≧ 10 nm), and more preferably 15 nm or more (T5 ≧ 15 nm). By doing so, even if a pinhole is generated in the insulating film 16b1 when the insulating film 16b1 is formed by the plasma CVD method, the pinhole of the insulating film 16b1 is insulated when the insulating film 16d is formed by the plasma ALD method. The film 16d can be accurately embedded. Similarly, the thickness T3 of the insulating film 16c is preferably 10 nm or more (T3 ≧ 10 nm), and more preferably 15 nm or more (T3 ≧ 15 nm). By doing so, even if a pinhole is generated in the insulating film 16b2 when the insulating film 16b2 is formed by the plasma CVD method, the pinhole of the insulating film 16b2 is insulated when the insulating film 16c is formed by the plasma ALD method. The film 16c can be accurately embedded. Thereby, the effect of preventing the invasion of water by the protective film 16 can be obtained more accurately.

Further, in the case of the protective film 16 of FIG. 24, the thickness T1 of the insulating film 16a, the thickness T3 of the insulating film 16c, and the thickness T5 of the insulating film 16d are the same as each other (that is, T1 = T3 = T5). Is preferable. Further, it is preferable that the thickness T2a of the insulating film 16b1 and the thickness T2b of the insulating film 16b2 are the same as each other (that is, T2a = T2b). As a result, the balance of stress in the protective film 16 is improved, and the effect of improving the bending resistance of the protective film 16 can be further enhanced.

Further, in the case of the protective film 16 of FIG. 24, it is more preferable that the insulating film 16a, the insulating film 16c, and the insulating film 16d are formed under the same film forming conditions. The film forming conditions include, for example, the type and flow rate of the raw material gas used in the first step, the type and flow rate of the reaction gas used in the third step, the magnitude and frequency of the high frequency power in the third step, and the substrate temperature ( Film formation temperature) and so on. Further, it is more preferable that the insulating film 16b1 and the insulating film 16b2 are formed under the same conditions. The film forming conditions include, for example, the type and flow rate of the gas used in the plasma CVD method, the substrate temperature (deposition temperature), and the like. If the insulating film 16a, the insulating film 16c, and the insulating film 16d are formed under the same film forming conditions, the direction of the stress is the same and the magnitude of the stress is the same for the insulating film 16a, the insulating film 16c, and the insulating film 16d. Absolute value) can be about the same. Further, if the insulating film 16b1 and the insulating film 16b2 are formed under the same film forming conditions, the direction of stress is the same for the insulating film 16b1 and the insulating film 16b2, and the magnitude (absolute value) of the stress is about the same. Can be. As a result, the balance of stress in the protective film 16 is improved, and the effect of improving the bending resistance of the protective film 16 can be further enhanced.

Although the invention made by the present inventor has been specifically described above based on the embodiment thereof, the present invention is not limited to the embodiment and can be variously modified without departing from the gist thereof. Needless to say.

1 Display device 2 Display unit 3 Circuit unit 9 Glass substrate 10 Substrate 11 Substrate 12 Passion film 13 Electrode layer 13, 15 Electrode layer 13a, 15a Electrode 14 Organic layer 16, 116, 216, 316 Protective film 16a, 16b, 16c, 216b , 216c, 316a, 316b Insulation film 17 Resin film 18 Underlayer 21 Formation device 22 Load lock chamber 23 Transfer chamber 24, 25, 26 Chamber 27 Processing object 31 Stage 32 Shower head 33 Antenna 34 Exhaust part 41 Stage 42 Upper electrode 43 Exhaust part 44 Gas introduction part 45 Gas discharge part 46 High-frequency power supply T1, T2, T2a, T2b, T3, T4, T5 Thickness

Claims (15)

A method for manufacturing a display device having an organic EL element, which comprises the following steps:
(A) A step of forming the organic EL element on a flexible substrate;
(B) A step of forming a protective film made of an inorganic insulating material so as to cover the organic EL element;
Here, the step (b) is
(B1) A step of forming a first insulating film by using a plasma ALD method so as to cover the organic EL element.
(B2) A step of forming a second insulating film on the first insulating film by using a plasma CVD method.
(B3) A step of forming a third insulating film on the second insulating film by using the plasma ALD method.
Have,
The protective film is formed by the laminated film composed of the first insulating film, the second insulating film, and the third insulating film.
Each of the first insulating film and the third insulating film has a stress in the direction opposite to the stress direction of the second insulating film.
The second thickness of the second insulating film is larger than the sum of the first thickness of the first insulating film and the third thickness of the third insulating film. In the method for manufacturing a display device according to claim 1,
The second insulating film is a method for manufacturing a display device, which comprises a silicon nitride film, a silicon oxide film, or a silicon oxynitride film. In the method for manufacturing a display device according to claim 1,
A method for manufacturing a display device, wherein the second insulating film is made of a silicon nitride film. In the method for manufacturing a display device according to claim 2.
A method for manufacturing a display device, wherein the first insulating film and the third insulating film are each made of an insulating film containing Al. In the method for manufacturing a display device according to claim 2.
The first insulating film is made of an aluminum oxide film, an aluminum nitride film or an aluminum nitride film.
A method for manufacturing a display device, wherein the third insulating film is made of an aluminum oxide film, an aluminum nitride film, or an aluminum nitride film. In the method for manufacturing a display device according to claim 2.
The first insulating film is made of an aluminum oxide film.
A method for manufacturing a display device, wherein the third insulating film is made of an aluminum oxide film. In the method for manufacturing a display device according to claim 3,
A method for manufacturing a display device, wherein the second insulating film has compressive stress, and each of the first insulating film and the third insulating film has tensile stress. In the method for manufacturing a display device according to claim 1,
A method for manufacturing a display device, wherein the second thickness of the second insulating film is larger than 20 nm. In the method for manufacturing a display device according to claim 8,
A method for manufacturing a display device, wherein the third thickness of the third insulating film is 10 nm or more. In the method for manufacturing a display device according to claim 9.
A method for manufacturing a display device, wherein the first thickness of the first insulating film is the same as the third thickness of the third insulating film. In the method for manufacturing a display device according to claim 1,
A method for manufacturing a display device, wherein the thickness of the protective film is 200 nm or less. In the method for manufacturing a display device according to claim 1,
The second insulating film is in contact with the first insulating film, and is in contact with the first insulating film.
A method for manufacturing a display device, wherein the third insulating film is in contact with the second insulating film. In the method for manufacturing a display device according to claim 1,
In the step (b2), a method for manufacturing a display device, wherein the second insulating film is formed by using an ICP-CVD method. In the method for manufacturing a display device according to claim 1,
After the step (b),
(C) A step of forming a resin film on the protective film,
A method of manufacturing a display device, further comprising. A method for manufacturing a display device having an organic EL element, which comprises the following steps:
(A) A step of forming the organic EL element on a flexible substrate;
(B) A step of forming a protective film made of an inorganic insulating material so as to cover the organic EL element;
Here, the step (b) is
(B1) A step of forming a first insulating film by using a plasma ALD method so as to cover the organic EL element.
(B2) A step of forming a second insulating film on the first insulating film by using a plasma CVD method.
(B3) A step of forming a third insulating film on the second insulating film by using the plasma ALD method.
(B4) A step of forming a fourth insulating film on the third insulating film by using a plasma CVD method.
(B5) A step of forming a fifth insulating film on the fourth insulating film by using the plasma ALD method.
Have,
The second insulating film and the fourth insulating film have stresses in the same direction, and the second insulating film and the fourth insulating film have stresses in the same direction.
The first insulating film, the third insulating film, and the fifth insulating film have stresses in directions opposite to the stress directions of the second insulating film and the fourth insulating film, respectively.
The protective film is formed by a laminated film composed of the first insulating film, the second insulating film, the third insulating film, the fourth insulating film, and the fifth insulating film.
The total thickness of the second insulating film and the fourth insulating film is larger than the total thickness of the first insulating film, the third insulating film, and the fifth insulating film.

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