FILM FORMING METHOD AND FILM FORMING DEVICE

Abstract

A film forming method, including providing a substrate in a lower section of a chamber, providing a mask on the substrate via an insulating body, spraying charged fine particles of a film forming material into a space inside the chamber, applying a potential of an opposite polarity to that of the charged fine particles to the substrate and applying a potential of the same polarity as that of the charged fine particles to the mask so as to deposit the fine particles on the substrate and form a film.

Claims

1. A film forming method, comprising: providing a substrate in a lower section of a chamber; providing a mask on the substrate via an insulating body; spraying charged fine particles of a film forming material into a space inside the chamber by a spraying device; applying a potential of an opposite polarity to that of the charged fine particles to the substrate and applying a potential of the same polarity as that of the charged fine particles to the mask so as to deposit the fine particles on the substrate and form a film, wherein a fine particulization device that comprises a piezoelectric device to vibrate the fine particles, and mesh nozzles, is used as the spraying device.

2. The film forming method of claim 1, wherein the substrate is formed from a transparent body.

3. The film forming method of claim 1, wherein the insulating body is either an insulating layer covering the mask or an insulating spacer interposed between the mask and the substrate.

4. The film forming method of claim 1, wherein: the insulating body comprises an insulating layer covering the mask; and projecting edges that project downward with acute angle tips are formed at the insulating layer at a periphery of a bottom face of the mask, such that the projecting edges make close contact with the substrate.

5. The film forming method of claim 1, wherein the insulating body is an insulating layer covering the mask and an insulating spacer interposed between the mask and the substrate.

6. The film forming method of claim 1, wherein the film forming material is an organic EL material.

7. A film forming device employed in the film forming method of claim 1, the film forming device comprising: an atomizer that forms the fine particles of the film forming material at a predetermined particle diameter and sprays the fine particles into the chamber; a charging device that charges the fine particles entering the chamber; a substrate potential application device that applies a potential of an opposite polarity to that of the charged fine particles to the substrate; and a mask potential application device that applies a potential of the same polarity as that of the charged fine particles to the mask, wherein the atomizer is a fine particulization device that comprises a piezoelectric device to vibrate the fine particles, and mesh nozzles.

8. (canceled)

Description

BRIEF DESCRIPTION OF DRAWINGS

[0026] FIG. 1 is a schematic view illustrating a film forming device of an exemplary embodiment.

[0027] FIG. 2 is an enlarged cross-section of part of the film forming device illustrated in FIG. 1.

[0028] FIG. 3 is an enlarged cross-section of part of a modified example of a film forming device of an exemplary embodiment.

[0029] FIG. 4 is an enlarged cross-section of part of a modified example of a film forming device of an exemplary embodiment.

[0030] FIG. 5 is an enlarged cross-section of part of a modified example of a film forming device of an exemplary embodiment.

[0031] FIG. 6 is an enlarged cross-section of part of a modified example of a film forming device of an exemplary embodiment.

[0032] FIG. 7 is a circuit diagram illustrating an electrical circuit of a substrate potential application device and a mask potential application device.

DESCRIPTION OF EMBODIMENTS

[0033] Detailed explanation follows regarding an exemplary embodiment of a film forming method and a film forming device of the present invention, with reference to the drawings.

[0034] FIG. 1 illustrates a chamber 1 and an atomizer 5 including plural nozzles 4 that spray fine particles 3 of a film forming material into the chamber 1 from a side wall 2. The fine particles 3 have a uniform particle diameter of from 2 m to 6 m, and preferably of 3.3 m0.2 m. The fine particles 3 are ejected into the chamber 1 by a piezoelectric device (not illustrated in the drawings) used to generate a spray from the atomizer 5 through the mesh-shaped nozzles 4 (having diameters of from 1 m to 5 m, and preferably produced to a precision of 2.5 m0.2 m, for example). Charging devices 6 are provided to charge the fine particles 3 at a negative potential, for example.

[0035] A substrate 7 formed from a transparent body is provided at the bottom of the chamber 1. A mask 8 manufactured by electroforming is provided on the substrate 7. A mask with a controllable coefficient of thermal expansion is employed as the mask 8 (a vapor deposition mask disclosed in Japanese Patent No. 4401040, obtained by the present applicant). In order to prevent electrical conductivity, the mask 8 is covered by an insulating layer 9 of a resin or the like formed using electrocoating, as illustrated in FIG. 2. Note that a cationic electrocoating resin (an epoxy-based resin or an epoxy-polyamide-based resin) is preferably employed in this electrocoating. Alternatively, instead of electrocoating, a coating of Parylene (para-xylene-based polymer) may be applied. The insulating layer 9 is an example of an insulator. This may employ a resin, for example 9T-Nylon, this being a type of semi-aromatic Nylon (Nylon is a registered trademark).

[0036] A substrate potential application device 10 applies the substrate 7 with a positive potential, this being the opposite polarity to that of the fine particles 3 charged with a negative potential. A mask potential application device 11 applies the mask 8 with a negative potential, this being the same polarity as that of the fine particles 3 charged with a negative potential. These devices will be described in detail later.

[0037] Explanation follows regarding the film forming method.

[0038] The fine particles 3 are ejected into the chamber 1 by the atomizer 5 with a uniform size particle diameter of, for example, 3.3 m0.2 m.

[0039] The ejected fine particles 3 are, for example, charged to a negative potential by the charging devices 6. The substrate 7 is applied with a positive potential, this being the opposite polarity to that of the charged fine particles 3, by the substrate potential application device 10. The mask 8 is applied with a negative potential, this being the same polarity as that of the charged fine particles 3, by the mask potential application device 11. The mask 8 is covered by the insulating layer 9, and so the mask 8 and the substrate 7 are insulated from each other.

[0040] Accordingly, the fine particles 3 charged to a negative potential are repelled by the mask 8 applied with a negative potential of the same polarity thereto, and are attracted to the substrate 7 applied with positive potential of the opposite polarity thereto. The fine particles 3 thus pass through holes 12 in the mask 8 and are deposited on the substrate 7, thereby forming films 13 with good precision.

[0041] The mask 8 is then removed from the substrate 7 to obtain organic EL elements configured by the films 13.

[0042] The fine particles 3 with uniformly sized particle diameters of for example 3.3 m0.2 m are ejected into the chamber 1. This has been confirmed to enable fine 10 m squares to be obtained for the pattern coating dimensions with these particle diameters, far surpassing those using a vapor deposition mask.

[0043] Although the fine particles 3 are liquid when sprayed, since the fine particles 3 are sufficiently fine, with uniform particle diameters of, for example, 3.3 m0.2 m, the fine particles 3 solidify at the same time as they are being deposited on the substrate 7, and uneven color resulting from surface tension or the like has been confirmed not to occur.

[0044] Moreover, since the substrate 7 is disposed at the lowest part of the chamber 1, and the mask 8 is disposed directly above the substrate 7, deformation and distortion of the substrate 7 due to gravity, such as arises in general vapor deposition methods, can be avoided even when employing large substrates.

[0045] The film forming device of the present disclosure is a device that operates in a humidity free nitrogen atmosphere in a dry atmospheric pressure environment, enabling manufacturing costs of the device to be kept low.

[0046] Forming the substrate 7 from a transparent body is effective for the production of color filters for liquid crystal displays when dyes, pigment inks, or the like are employed.

[0047] As illustrated in FIG. 3, ideally projecting edges 14 that project downward with acute angle tips are formed to the insulating layer 9 at the periphery of the bottom face of the mask 8, so as to place the projecting edges 14 in close contact with the substrate 7. The reason for adopting such a configuration is so that, during film forming, the fine particles 3 do not burrow under the mask 8 due to the close contact achieved at the acute angles of the projecting edges 14 with the substrate 7 at the periphery of the bottom face of the mask 8. This enables the fine particles 3 to be deposited on the substrate 7 only at predetermined locations, enabling the films 13 to be obtained with very high precision.

[0048] As illustrated in FIG. 4, in cases in which the mask 8 is not covered with an insulating layer, the mask 8 is provided with insulating spacers 15, serving as an example of insulating bodies, interposed above the substrate 7. The insulating spacers 15 are disposed at both ends of the bottom face of each element of the mask 8 so as to be disposed between the mask 8 and the substrate 7. The material employed for the insulating spacers 15 is preferably 9T Nylon (Nylon is a registered trademark), polyether ether ketone (PEEK), or a silicone resin which have excellent heat resistance, insulating properties, and ease of processing. The insulating spacers 15 enable the mask 8 and the substrate 7 to be completely insulated from each other even without covering the mask 8 with an insulating layer.

[0049] The insulating body may be configured by the insulating spacers 16 that cover the entire bottom face of the mask 8, as illustrated in FIG. 5.

[0050] Insulating spacers 15 may be interposed between the substrate 7 and a mask 8 that has been covered by an insulating layer 9, as illustrated in FIG. 6.

[0051] When the substrate 7 employed is small, any configuration from out of a configuration in which the mask 8 is covered by the insulating layer 9 (FIG. 2, FIG. 3), a configuration in which the insulating spacers 15 are interposed between the mask 8 and the substrate 7 (FIG. 4), or a configuration in which the insulating spacers 16 are interposed between the mask 8 and the substrate 7 (FIG. 5). A configuration in which the mask 8 is covered by the insulating layer 9 (FIG. 2, FIG. 3) is preferable from the perspective of mass production.

[0052] When the substrate 7 employed is large, cracks might develop in the insulating layer 9 due to the mask 8 sagging under its own weight. Accordingly, a configuration in which the mask 8 is covered by the insulating layer 9 and the insulating spacers 15 are interposed between the mask 8 and the substrate 7 (FIG. 6) is preferable, and this enables films 13 to be obtained with very high precision.

[0053] The thickness of the insulating layer 9 or the insulating spacers 15 is set in consideration of the temperature inside the chamber 1 and the production line speed. Productivity suffers if the thickness thereof is 25 m or less. The thickness is preferably from 40 m to 60 m in consideration of ease of production, productivity, and mechanical strength.

[0054] FIG. 7 illustrates an electrical circuit 17 used to apply voltages to the substrate potential application device 10 and the mask potential application device 11. The electrical circuit 17 is a rectifier circuit that converts alternating current to direct current. AC at 100V supplied from an alternating current power source 18 is converted to AC at from 2V to 10V by a transformer 20 when an interlock switch 19 is switched ON. The alternating current is converted into direct current by a bridge circuit 21 employing four diodes, and is then converted into a ripple-free direct current by a smoothing capacitor 22 and charged into an electrical double layer capacitor 23. The electrostatic capacitance of the capacitor 22 is from 200 F to 300 F. The anode side of the direct current charged in the electrical double layer capacitor 23 is connected to the substrate potential application device 10, and the cathode side thereof is connected to the mask potential application device 11.

[0055] The electrical double layer capacitor 23 (EDLC) referred to here is a large high capacitance capacitor with an electrostatic capacitance of from 50 F to 100 F. The electrical double layer capacitor 23 has a capacitance of 10.sup.6 to 10.sup.8 times that of a conventional aluminum electrolytic capacitor.

[0056] The production of large displays, such as 2 m1.5 m displays, has recently been increasing. A certain amount of time is required to apply an electrostatic charge to large substrates and masks corresponding to such large displays. A large high capacitance electrical double layer capacitor (EDLC) is accordingly preferably employed in order to improve production line speeds. In the present exemplary embodiment, employing the electrical double layer capacitor 23 such as that described above enables electrostatic charge to be charged into and discharged from large substrates and masks in an instant.

[0057] The entire disclosure of Japanese Patent Application No. 2017-102068, filed on May 23, 2017, is incorporated by reference in the present specification.

[0058] All cited documents, patent applications, and technical standards mentioned in the present specification are incorporated by reference in the present specification to the same extent as if each individual cited document, patent application, or technical standard was specifically and individually indicated to be incorporated by reference.