WO2015010036A1

WO2015010036A1 - Method for manufacturing barrier films

Info

Publication number: WO2015010036A1
Application number: PCT/US2014/047220
Authority: WO
Inventors: Walter SEAMAN; John E. Madocks
Original assignee: General Plasma Inc
Current assignee: General Plasma Inc
Priority date: 2013-07-18
Filing date: 2014-07-18
Publication date: 2015-01-22
Anticipated expiration: 2016-01-18

Abstract

A method for manufacturing vacuum deposited barrier films that prevent water vapor and/or oxygen gas permeation, while minimizing the amount of particles and contaminants on the surface to which the barrier film is to be applied is provided. The method includes protecting a to-be-coated surface with an adhesive tacky film through vacuum pump down and from roller contact, etc. Surfaces treated with the method include flexible web substrates and rigid substrates such as glass or metal. A glass substrate with a pre-coated film stack, for example, a glass sheet with coatings for making an organic light-emitting diode (OLED) display can be protected with a tacky film per the inventive method. Small substrates such as glass lenses can also benefit from the inventive method. As can other substrates such as rolls of metal strip and substrates with curved or pre-cut shapes.

Description

METHOD FOR MANUFACTURING BARRIER FILMS

RELATED APPLICATIONS

[0001] This application claims priority benefit of US Provisional Application Serial Number 61/847,956 filed July 18, 2013; the contents of which are hereby incorporated by reference.

FIELD OF THE INVENTION

[0002] The present invention in general relates to barrier films and in particular, to vacuum deposited barrier films to prevent water vapor and/or oxygen gas permeation and to the manufacturing of such films.

BACKGROUND OF THE INVENTION

[0003] A significant challenge in making a vacuum deposited barrier film is particles on the substrate before the barrier film is deposited. Particles, such as dust, compounds used to ease web winding operations (anti-blocking compounds) and machine generated debris, land on the substrate and cause pin-holes and poor barrier performance. Particles can be added to the substrate surface during the substrate manufacturing process, (for example, when anti-blocking compounds are applied to flexible webs), and/or during the vacuum coating operation prior to the barrier film deposition.

[0004] An existing approach to reduce or eliminate particles from the to-be-coated surface is to contact the surface with a tacky roll. Typically, a tacky roller is in contact with the substrate surface where particles adhere to this roller and are removed from the substrate. A second roller cleans the particles building up on the first roller to extend the effective life of the first tacky roll. However, this method is not fully effective for several reasons: 1) This method does nothing to prevent particles from landing on and becoming embedded into the substrate surface in the first place. 2) Surface damage due to roller contact is not considered in this approach. 3) The effectiveness of the tacky roll degrades over time as particles build up and begin to be added back onto the substrate.

[0005] Thus there exists a need for a device and process for making a vacuum deposited barrier film that is free of particles on the substrate before the barrier film is deposited. SUMMARY OF THE INVENTION

[0006] A method for depositing barrier films, while minimizing the amount of particles and contaminants on a deposition surface to which the barrier film is applied is provided. A substrate with a tacky film already applied to a deposition surface of the substrate is supplied into a vacuum chamber. The tacky film is then removed from the substrate leaving the deposition surface clear of particles and contaminants that otherwise accumulate on the surface outside the vacuum chamber. The substrate is coated with the barrier film. The tacky film has a backing for removal and storage in a roll. The removing of the tacky film is done after all physical contact with the to-be-coated deposition surface occurs and after the vacuum chamber has reached process vacuum conditions. In other embodiments, the tacky film is removed in a reduced pressure ante-chamber to the vacuum chamber in which deposition occurs. The method further includes treating the deposition surface with an ion beam to improve adhesion of the barrier film. The substrate is flexible and supplied in a roll; or may be sheets for example of, glass, or metal. The substrate to be treated may be curved or a pre-cut shape. Coating is by plasma-enhanced chemical vapor deposition (PECVD), or by physical vapor deposition (PVD). The method may further include applying a secondary tacky film to the barrier film. The barrier film is a silicon nitride containing material, a silicon oxide, or an aluminum oxide film.

[0007] A system for carrying out the method for depositing barrier films, while minimizing the amount of particles and contaminants on a deposition surface to which the barrier film is applied is provided. The system includes a supply of a substrate with a tacky film already applied to a deposition surface of the substrate. The film supply is in communication with a vacuum chamber directly or via an optional ante-chamber. A take up roll is provided in the system for removing the tacky film in the vacuum chamber, or ante-chamber. One or more plasma sources are provided in the vacuum chamber for coating the substrate with the barrier film. The system in some embodiments has an ion source that emits an ion beam and treats the surface of the substrate to improve adhesion of the barrier film, and a cooled rotating drum for supporting and moving the substrate within the vacuum chamber. In specific embodiments a secondary roll of tacky film within the vacuum chamber is provided for application over the barrier film. The system plasma source is configured for plasma-enhanced chemical vapor deposition (PECVD) or physical vapor deposition (PVD).

BRIEF DESCRIPTION OF THE DRAWINGS [0008] The present invention is further detailed with respect to the following drawings that are intended to show certain aspects of the present invention, but should not be construed as a limit on the practice of the present invention.

[0009] FIG. 1 shows a vacuum web coater implementing the inventive method; and

[0010] FIG. 2 diagrams the steps of an embodiment of the inventive method of barrier coating manufacture.

DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention has utility for manufacturing vacuum deposited barrier films that prevent water vapor and/or oxygen gas permeation, while minimizing the amount of particles and contaminants on the surface to which the barrier film is to be applied.

[0012] It is to be understood that in instances where a range of values are provided that the range is intended to encompass not only the end point values of the range but also intermediate values of the range as explicitly being included within the range and varying by the last significant figure of the range. By way of example, a recited range of from 1 to 4 is intended to include 1-2, 1-3, 2-4, 3-4, and 1-4.

[0013] Referring now to the figures, FIG. 1 illustrates a simplified drawing of a vacuum thin film coating system 100 for depositing plasma-enhanced chemical vapor deposition (PECVD), but can also be done by PVD (physical vapor deposition) methods such as sputtering or evaporation, films on a flexible substrate 23. Coating system 100 includes vacuum pumps (not shown) to remove atmosphere from the chamber 8 prior to the coating operation. A chilled drum 14 supports the flexible substrate 23 and helps to maintain the substrate 23 at an acceptable temperature during the PECVD process. System 100 has an unwind roll having a core 3 supporting a roll 1 of uncoated flexible substrate. As per an embodiment of the inventive method, described further in FIG. 2, uncoated flexible substrate 23, termed 'web', has a tacky adhesive and a thin adhesive support film 12 adhered to web 23 and wound into roll 1. Preferably, the protective tacky film 12 is applied to the web 23 during the web manufacturing process when the web is free of particles of any kind. A roll 1 of web 23' with tacky film with backing 12 is installed on core 3 and threaded through the web path of the coater. As shown in the drawing of coater 100, roller 6 of the web path contacts the side of web 23' that will be coated with a barrier film. In this case however, the coated surface of web 23 ' is protected from contacting roller 6 by tacky film 12. Nip roll 13 on chill drum 14 also touches the to-be-coated surface of tacky film 12. Nip roll 13 presses web 23' against drum 14 to keep the web 23' and 23 from slipping as drum 14 turns. At nip roll 13, tacky film 12 is peeled away and rolled up on core 11. After film 12 has been peeled off web 23 (lacking tacky film and backing 12), the web to-be-coated surface is clean and free of particles. Importantly, after film 12 is removed, no further contact to the to-be-coated side of web 23 is made until after the barrier coating is deposited.

[0014] In some inventive embodiments, the vacuum chamber 8 is partitioned to form an antechamber 8' and a plasma deposition chamber 8". The ante-chamber 8' in still other embodiments having a separate pumping system that affords a user with the option of having a different level of reduced pressure for film removal relative to deposition. It is appreciated that any solvent de- gassing or possible contaminants associated with the film 12 occurs in the ante-chamber thereby reducing wear on the deposition chamber pumping system and retaining controlled plasma deposition conditions. Possible contaminants associated with the film 12 include gaseous organic molecules and polymeric cure catalysts.

[0015] The tack of the film 12 is readily quantified using conventional techniques such as ASTM 3121. The tack, or related adjective "tacky" referring to a film herein denotes a required to separate the adhesive from the adherend deposition substrate at the interface therebetween shortly after the film and substrate surface have been brought into contact under a load equal only to the weight of the film on a 6.45 cm² contact area. Tacky film 12 typically has a qualitative "finger tack" that generally corresponds to values of between 5 and 60 Newtons per centimeter (N/cm).

[0016] Continuing with FIG. 1, prior to PECVD of the barrier film, an ion source 24 emits ion beam 25 and treats the to-be-coated surface to improve adhesion. Pretreatment of a web to improve adhesion is well known in the industry. After pretreatment, one or more PECVD sources, 18 deposit a barrier film 18B on web 23. The plasma 19 of source 18 breaks down a precursor gas as is well known in PECVD technology. Source 18 is an AC ion source that has previously been the subject of patent application publications PCT/US2009/067149 and US2005/0247885 to the same assignee of the instant application. After a barrier film 18B is deposited, the web 23 can be conveyed to a rewind core 4 and rolled up into roll 2. Alternately, another adhesive tacky film 21 can be applied to the coated surface of web 23 from core 16 and roll 10. Nip roll 15 presses the tacky film onto web 23. In the case of applying a new tacky film, the combined web 23 and tacky film 21, indicated as 22, is wound up as roll 2. Note that roll 7, in particular inventive embodiments on the rewind section of the web path, contacts the coated side of web 23. In some cases, because the barrier film has already been deposited on web 23, the barrier properties are not affected by roller contact. The addition of a new tacky film will be dependent on the sensitivity of the barrier film and the requirements for follow-on coatings or converting operations.

[0017] FIG. 2 with reference to FIG. 1 diagrams an embodiment of an improved method for depositing a vacuum coated barrier film. As shown, the steps are as follows:

a) Start with a base substrate 23 that has an adhesive tacky film with adhesive backing 12 already adhered to the clean, to-be-coated substrate surface 23 to form web 23 '. This is typically done by the substrate manufacturer in a clean environment, such as a clean room, so that particles are not incorporated into the interface between the substrate 23 and tacky film 12. One benefit of the tacky film is that even if particles are left at the interface, the particles are retained with the adhesive when the tacky film 12 is removed in the vacuum chamber.

b) Put the substrate (flexible web 23' on roll 1) with adhered tacky film into the vacuum chamber 8 and thread the web path with the assembled film. Remove the tacky film 12 and wind on core 11 and wind web 23 (substrate and barrier) on rewind core 4.

c) Seal and pump down vacuum chamber 8 to process pressure. During the vacuum pumping process it is common for particles to be stirred up and distribute on rollers and other vacuum chamber and web path components.

d) Once the chamber is pumped down, start to move the web 23 and deposit the barrier film 18b on web 23. As described in FIG 1, the tacky film 12 is removed just prior to web 23 treatment and barrier film 18B deposition. Importantly, the tacky film 12 is only removed after all physical contact with the to-be-coated surface occurs and after the vacuum chamber has reached process vacuum conditions. By leaving the tacky film 12 covering web 23 until after these conditions are past, many fewer particles reside on the to-be-coated web surface 23 than if no tacky film 12 were used or if the film were removed earlier.

e) Deposit the barrier film 18B on the substrate 23. This is done preferably by PECVD process but can also be done by PVD (physical vapor deposition) methods such as sputtering or evaporation. The barrier film 18B preferably is a silicon nitride containing material but can also be a silicon oxide or an aluminum oxide film. These films can incorporate carbon depending upon the precursor used in the PECVD process. [0018] At this point the method is complete and an improved barrier film 18B is created. Often, particles added onto the coated web 23 do not affect the barrier performance, and the web 23 can simply be wound up and sent to other converting operations.

[0019] Optionally, as shown in FIG 1, a second tacky film 21 can be applied to the barrier deposited web 23 to form assembly 22. This second tacky film 21 helps to keep the surface of barrier film on web 23 protected from damage due to sharp points on rollers and prevents particles from reaching the barrier film 18B coated surface of web 23.

[0020] The inventive method has been diagramed and described for a flexible web substrate. Protecting a to-be-coated surface with an adhesive tacky film through vacuum pump down and from roller contact, etc., is a useful method for treating other substrates as well. For instance, the method can be applied to rigid substrates such as glass or metal. A glass substrate with a pre- coated film stack, for example, a glass sheet with coatings for making an organic light-emitting diode (OLED) display can be protected with a tacky film per the inventive method. Small substrates such as glass lenses can also benefit from the inventive method. As can other substrates such as rolls of metal strip and substrates with curved or pre-cut shapes.

[0021] The foregoing description is illustrative of particular embodiments of the invention, but is not meant to be a limitation upon the practice thereof. The following claims, including all equivalents thereof, are intended to define the scope of the invention.

Claims

1. A method for depositing barrier films, while minimizing the amount of particles and contaminants on a deposition surface to which the barrier film is applied, the method comprising:

supplying a substrate with a tacky film applied to a deposition surface of said substrate to a vacuum chamber or an ante-chamber of said vacuum chamber;

removing said tacky film from said substrate leaving said deposition surface clear of particles and contaminants; and

coating said substrate with said barrier film.

2. The method of claim 1 further comprising treating said deposition surface with an ion beam to improve adhesion of said barrier film.

3. The method of any of claims 1 to 2 wherein said substrate is flexible and supplied in a roll.

4. The method of any of claims 1 to 2 wherein said substrate is rigid.

5. The method of any of claims 1 to 2 wherein said substrate is glass or metal.

6. The method of claim 1 wherein said coating is by plasma-enhanced chemical vapor deposition (PECVD).

7. The method of claim 1 wherein said coating is by physical vapor deposition (PVD).

8. The method of claim 1 further comprising applying a secondary tacky film to said barrier film.

9. The method of claim 1 wherein said barrier film is a silicon nitride containing material.

10. The method of claim 1 wherein said barrier film is a silicon oxide or an aluminum oxide film.

11. The method of claim 1 wherein said substrate is curved or a pre-cut shape.

12. The method of claim 1 wherein said removing is done after all physical contact with the to-be-coated deposition surface occurs and after the vacuum chamber has reached process vacuum conditions.

13. The method of claim 12 wherein said removing is done in said ante-chamber.

14. The method of claim 12 wherein said removing is done in said vacuum chamber.

15. The method of claim 1 wherein said tacky film has a backing for removal and storage in a roll.

16. A system for carrying out the method of claim 1, said system comprising:

a supply of a substrate with a tacky film already applied to a deposition surface of said substrate;

a vacuum chamber optionally having an ante-chamber;

a take up roll for removing said tacky film in said vacuum chamber or an antechamber to said vacuum chamber; and

one or more plasma sources for coating said substrate within said vacuum chamber with said barrier film.

17. The system of claim 16 further comprising an ion source that emits an ion beam and treats the surface of said substrate to improve adhesion of said barrier film.

18. The system of claim 17 further comprising a rotating drum for supporting and moving said substrate within said vacuum chamber.

19. The system of claim 17 wherein said drum is cooled.

20. The system of claim 6 further comprising a secondary roll of tacky film within said vacuum chamber for application over said barrier film.

21. The system of claim 16 wherein said plasma source is configured for plasma- enhanced chemical vapor deposition (PECVD).

22. The system of claim 14 wherein said plasma source is configured for physical vapor deposition (PVD).