BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic view of a fabrication and selective coating system constructed in accordance with an embodiment of the invention.
FIG. 2 is a schematic view of a deposition machine for use in the system of FIG. 1.
FIG. 3 is a schematic view of the deposition chamber of the deposition machine of FIG. 2.
FIG. 4 is a schematic view illustrating a graded deposition process within the deposition chamber of the deposition machine of FIG. 2.
FIG. 5 is a schematic view of a selective deposition machine for use in the system of FIG. 1 and constructed in accordance with an embodiment of the invention.
FIG. 6 is a schematic view of an object being selectively coated in the selective deposition machine of FIG. 5.
FIG. 7 is a schematic view of a selective deposition machine for use in the system of FIG. 1 and constructed in accordance with an embodiment of the invention.
FIG. 8 is a schematic view of an object being selectively coated in the selective deposition machine of FIG. 7.
FIG. 9 is a schematic view of a shadow mask or web for use in the selective deposition machines of FIG. 5 or 7 and constructed in accordance with an embodiment of the invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Referring to FIG. 1, there is shown a fabrication and selective coating system 5 that includes a substrate deposition machine 10, a fabrication assembly 110, and a selective coating assembly 210. Arrows are provided to indicate the likely pathway for the coating and fabrication of objects, such as, for example, electronic devices. Examples of electronic devices include liquid crystal displays (LCDs); thin-film transistors (TFTs) and TFT arrays using organic, solution-processible inorganic materials; photovoltaic cells; integrated circuits; electrochromic devices; electrophoretic devices; sensors; energy storage devices, including batteries; electric luminescence devices, including OLEDs; components of medical diagnostic systems; and, any opto-electronic devices that need barrier protection. Specifically, a flexible or inflexible substrate is coated in the substrate deposition machine 10. The coated substrate is transferred to the fabrication assembly 110, in which an electronic device is assembled onto the coated substrate. Finally, in the selective coating assembly 210, the electronic device is selectively coated. The substrate deposition machine 10 may utilize a roll-to-roll mechanism or an in-process mechanism to transfer substrates through the machine.
With specific reference to FIGS. 1-4, the deposition machine 10 is illustrated including a first spool chamber 12, a deposition chamber 18, and a second spool chamber 30. The deposition machine 10 may be configured to produce a graded-composition coating, for example a graded-composition diffusion-barrier coating, on a substrate. The first spool chamber 12 includes a first spool 14 about which a web 40 is wound. The web 40 extends through the deposition chamber 18 and into the second spool chamber 30 to a second spool 32. In one exemplary embodiment, the first spool 14 is an unwinding spool and the second spool 32 is a winding spool. The web 40 may serve as a transportation device transporting a substrate through the deposition chamber 18; alternatively, the web 40 may serve as the substrate. Examples of substrates upon which deposition may occur include flexible substrates, such as, for example, films or sheets formed of plastic or metal, and inflexible substrates, such as, for example, blocks or plates formed of glass, metal or plastic.
Substrate materials that may benefit from having a graded-composition diffusion-barrier coating include organic polymeric materials, such as: polyethylene-terephthalate (“PET”); polyacrylates; polycarbonate; silicone; epoxy resins; silicone-functionalized epoxy resins; polyester, such as Mylar® (made by E.I. du Pont de Nemours & Co.); polyimide, such as Kapton® H or Kapton® E (made by du Pont), Apical® AV (made by Kanegafugi Chemical Industry Company), Upilex® (made by UBE Industries, Ltd.); polyethersulfones (“PES,” made by Sumitomo); polyetherimide such as Ultem® (made by General Electric Company); and polyethylene naphthalene (“PEN”).
Suitable coating compositions for the substrates organic, inorganic, or combinations thereof. These materials are typically reaction or recombination products of reacting plasma species and are deposited onto the substrate surface. Organic coating materials typically comprise carbon, hydrogen, oxygen, and optionally other minor elements, such as sulfur, nitrogen, silicon, etc., depending on the types of reactants. Suitable reactants that result in organic compositions in the coating are straight or branched alkanes, alkenes, alkynes, alcohols, aldehydes, ethers, alkylene oxides, aromatics, etc., having up to 15 carbon atoms. Inorganic and ceramic coating materials typically comprise oxide; nitride; carbide; boride; or combinations thereof of elements of Groups IIA, IIIA, IVA, VA, VIA, VIIA, IB, and IIB; metals of Groups IIIB, IVB, and VB; and rare-earth metals. For example, silicon carbide can be deposited onto a substrate by recombination of plasmas generated from silane (SiH4) and an organic material, such as methane or xylene. Silicon oxycarbide can be deposited from plasmas generated from silane, methane, and oxygen or silane and propylene oxide. Silicon oxycarbide also can be deposited from plasmas generated from organosilicone precursors, such as tetraethoxysilane (TEOS), hexamethyldisiloxane (HMDSO), hexamethyldisilazane (HMDSN), or octamethylcyclotetrasiloxane (D4). Silicon nitride can be deposited from plasmas generated from silane and ammonia. Aluminum oxycarbonitride can be deposited from a plasma generated from a mixture of aluminum tartrate and ammonia. Other combinations of reactants may be chosen to obtain a desired coating composition. The choice of the particular reactants is within the skills of the artisans. A graded composition of the coating is obtained by changing the compositions of the reactants fed into the reactor chamber during the deposition of reaction products to form the coating.
Coating thickness is typically in the range from about 10 nm to about 10000 nm, preferably from about 10 nm to about 1000 nm, and more preferably from about 10 nm to about 200 nm. It may be desired to choose a coating thickness that does not impede the transmission of light through the substrate, such as a reduction in light transmission being less than about 20 percent, preferably less than about 10 percent, and more preferably less than about 5 percent. The coating may be formed by one of many deposition techniques, such as plasma-enhanced chemical-vapor deposition (“PECVD”), radio-frequency plasma-enhanced chemical-vapor deposition (“RFPECVD”), expanding thermal-plasma chemical-vapor deposition (“ETPCVD”), sputtering including reactive sputtering, electron-cyclotron-resonance plasma-enhanced chemical-vapor deposition (“ECRPECVD”), inductively coupled plasma-enhanced chemical-vapor deposition (“ICPECVD”), or combinations thereof. Alternately, the coating may be formed through an evaporative process, a sputtering process, and an atomic layer deposition process.
Further discussion of suitable substrate materials, suitable coating compositions and suitable coating thicknesses is found in co-pending U.S. patent application Ser. No. 10/065,018, filed Sep. 11, 2002 and currently owned by the assignee of the present patent application, the entirety of which is incorporated herein by reference.
An outlet 16 extends from the first chamber 12 to the deposition chamber 18 (FIG. 2). An outlet 28 extends from the deposition chamber 18 to the second chamber 32. The deposition chamber 18 includes at least a first chamber area or subchamber 20a and a second chamber area or subchamber 20b. The two chamber areas 20a, 20b are separated by a baffle 24. The baffle 24 has an opening 26. The opening 26 may be adjustable to control the rate of migration of deposition material through the opening 26. The deposition chamber 18 may be under vacuum. Further, for mechanical efficiency, the first and second chambers 12, 30 also may be under vacuum.
Each chamber area includes a deposition assembly, a deposition material outlet and a gas inlet. Specifically, and with reference to FIG. 3, the first chamber area 20a includes a gas inlet 50 extending to a deposition assembly 52. The gas inlet 50 receives a gaseous material which is transported to the deposition assembly 52 to create a deposition mist for the substrate being transported by the web 40. Any excess deposition material may be removed from the first chamber area 20a through the deposition material outlet 54. The second chamber area 20b includes a gas inlet 60 extending to a deposition assembly 62. The gas inlet 60 receives a gaseous material which is transported to the deposition assembly 62 to create a deposition mist for the substrate being transported by the web 40. Any excess deposition material may be removed from the second chamber area 20b through the deposition material outlet 64. The outlets 54, 64 each may be a single port in the respective deposition chamber area 20a, 20b. Alternatively, the outlets 54, 64 each may be multiple ports in the respective deposition chamber areas 20a, 20b. The location of each outlet 54, 64 within the deposition chamber areas 20a, 20b may be engineered to achieve desired gas flow and reactive species distribution.
To form a graded-composition coating on the substrate, it is envisioned that the material received by the first deposition assembly 52 has a different composition than the material received by the second deposition assembly 62. For example, one material may be an organic material, while a second material is an inorganic material or combinations of inorganic and organic.
With specific reference to FIG. 4, a function of the baffle 24 and the opening 26 is further described. The baffle 24 is adjusted to create an opening 26 of sufficient size and configuration to allow a certain amount of migration of deposition material to occur from one chamber area to another chamber area. As schematically illustrated in FIG. 4, a gaseous material deposited by the first deposition assembly 52 results in a coating portion 51 having a relatively high composition of the first gaseous material. Also, a gaseous material deposited by the second deposition assembly 62 results in a coating portion 61 having a relatively high composition of the second gaseous material.
Excess deposition material is evacuated from each of the chamber areas 20a, 20b by pumping the material out through the respective outlets 54, 64. The pumping causes a localized pressure differential in each chamber area causing a migration of excess material from most of each the chamber areas 20a, 20b toward the outlets 54, 64. When the pressures in deposition chamber areas 20a and 20b are maintained at the same level, a mix area 66 is formed immediately adjacent to the baffle 24. There is no localized pressure differential in the mix area 66. In this mix area 66, deposition material from the second chamber area 20b is equally likely to migrate into the first chamber area 20a as remain in the second chamber area 20b and deposition material from the first chamber area 20a is equally likely to migrate into the second chamber area 20b as remain in the first chamber area 20a. In this mix area 66, the relative compositions of the deposition materials begin to change. For example, the composition of the coating portion 51 begins to drop in the mix area 66, while the composition of the coating portion 61 begins to increase as an object moves from the first chamber area 20a through the mix area 66 and into the second chamber area 20b. The pressures in deposition chamber areas 20a and 20b also may be deliberately set to different levels to shift the mix area 66 to various locations within the deposition chamber 18. For example, pressure in deposition chamber area 20a may be set lower than that of deposition chamber area 20b. Thus, deposition material from both deposition chamber area 20a and deposition chamber area 20b is more likely to migrate to outlet 54 and therefore mix area 66 will move into deposition chamber 20a. By engineering opening 26, pressures in deposition chamber areas 20a and 20b, gaseous mixture material flows to deposition assemblies 52 and 62, geometry and location of deposition assemblies 52 and 62, geometry and location of outlets 54 and 64, and other process parameters, desired material distribution profiles can be achieved in the deposition chamber areas 20a, 20b.
According to an exemplary embodiment, the substrate to be coated is unwound from the first spool 14. As the web 40 travels through the deposition chamber 18, the first and second deposition assemblies 52, 62 begin depositing, respectively, the first and second materials. Through such a coating process, the substrate is coated by a plurality of materials and in varying compositions along the thickness of the coating.
Further discussion of the coating of substrates is found in co-pending U.S. patent application Ser. No. 11/315,248, filed Dec. 23, 2005 and currently owned by the assignee of the present patent application, the entirety of which is incorporated herein by reference.
It should be appreciated that the web 40 can be wound through the deposition chamber 18 toward the second spool 32 and then wound back through the deposition chamber 18 toward the first spool 14 to obtain a coating having more than three graded zones. Alternatively, and with specific reference to FIG. 4, it should be appreciated that numerous chamber areas or subchambers may be positioned side by side through which the web 40 may be transported. It should be further appreciated that such a substrate deposition machine 10 may be modularly assembled. For example, subchambers may be added to the deposition machine or removed from the deposition machine depending upon the particular application. By being able to add and remove subchambers to the entire substrate coating process, flexibility in applicability for the substrate deposition machine 10 is enhanced. Additionally, it should be appreciated that instead of a roll-to-roll design as illustrated in FIG. 2, the substrate deposition machine 10 may be designed as an “inline” coating machine where the web 40 is not unwound from one spool and wound onto another spool, but instead continually loops between a pair of spools.
After coating, the substrate is then fed into the fabrication assembly 110, where electronic devices are fabricated on the coated substrates. In the fabrication assembly 110, an electronic device 70 (FIG. 5) is fabricated. Some of the fabrication steps may be performed under vacuum or inert atmosphere, while other fabrication steps may be performed under atmospheric conditions. It should be appreciated that certain mechanical and chemical properties are desirable for substrates to be used for mounting electronic devices such as organic light-emitting devices (OLEDs), organic photovoltaic devices, thin-film transistors (TFTs) and TFT arrays using organic and solution-processible inorganic materials, and other more complicated circuits. Mechanical flexibility of the substrate is of importance for roll-to-roll processing, as described herein. Similar flexibility is also required for various end-use applications, such as, for example, “roll-up” displays. For “inline” fabrication, flexibility of the substrate is not as important. Chemical resistance is also important for substrate compatibility with the various solvents and chemicals used in the organic electronic device fabrication steps. Further discussion of important mechanical and chemical properties for suitable substrates is found in M. Yan, et al., “A Transparent, High Barrier, and High Heat Substrate for Organic Electronics,” IEEE, V. 93, N. 8, Aug. 2005, p. 1468-1477, the entirety of which is incorporated herein by reference.
The compositionally graded ultra-high barrier (UHB) coating described above can effectively stop defects from propagating through the coating thickness. In such a barrier structure, organic materials effectively decouple defects growing in the thickness direction but, instead of having a sharp interface between inorganic and organic materials, there are “transitional” zones where the coating composition varies continuously from inorganic to organic and vice versa. These “transitional” zones bridge inorganic and organic materials, which should result in a single layer structure with improved mechanical stability and stress relaxation relative to that of multilayer barrier structures.
Such a graded diffusion barrier coating also may be used to protect objects that are sensitive to environmental reactive species such as oxygen and water vapor. Such objects include, but are not limited to, organic light emitting diodes (OLEDs), liquid crystal devices (LCDs), photovoltaic cells, electrochromic devices, electrophoretic devices, and the like.
Referring now to FIG. 5, the selective coating assembly 210 is shown. Fabricated electronic devices 70 may be moved from the fabrication assembly to the selective coating assembly through the use of a web or through the use of a mechanism for moving individual electronic devices 70. Examples of such a mechanism include a vacuum chuck, a claw, or adhesive tape.
The selective coating assembly 210 includes a deposition chamber 18, a first transition chamber 212, a second transition chamber 214 and a web 140. The web 140 continually loops between a first spool 14 and a second spool 32. The first transition chamber 212 provides a transition between atmospheric conditions and vacuum or inert gas conditions. The second transition chamber 214 provides a transition between vacuum or inert gas conditions of the deposition chamber 18 and atmospheric conditions. The web 140 as used in the selective coating assembly 210 of FIG. 5 differs from the web 40 as used in the substrate deposition machine 10 of FIG. 2 in that the web 140 includes open spaces 142 (FIG. 9).
FIG. 6 illustrates an electronic device mounted on a substrate. The coating of the electronic device is a similar process to the coating of the substrate described with reference to FIG. 2. The electronic device 70 illustrated in FIG. 6 has been mounted on a substrate 72 that has been coated with a graded barrier coating in the substrate deposition machine 10. The substrate 72 may be flexible, as in a film or thin sheet of plastic or metal, or inflexible, as in a block of glass, plastic or metal. The illustrated electronic device 70, fabricated in the fabrication assembly 110, includes an OLED 74, an anode 76, and a cathode 78. A positive electric contact 77 extends from the anode 76 and a negative electric contact 79 extends from the cathode 78. It is generally desirable to coat all the portions of the electronic device 70, with the exception of the electric contacts 77, 79, to protect the electronic device 70 from reactive gaseous species such as moisture and oxygen, and/or from physical or chemical attack.
Specifically, with reference to FIGS. 6 and 9, a coating 82 is deposited on the electronic device 70 except over the electric contacts 77, 79. The coating 82 is delivered in the direction of the arrows A. The electronic device 70 is placed on the web 140 in such a way as to allow the openings 142 to be positioned to allow coating of the portions of the electronic device 70 that are to be coated and to inhibit coating of the portions of the electronic device 70 that are not to be coated, namely the electric contacts 77, 79. The positioning of the electronic device 70 on the web 140 may be accomplished through the use of reference pins 80 on the electronic device 70 and reference markers, such as reference slots 244a, 244b, on the web 140. Only one reference pin 80 is shown in FIG. 6 for ease of illustration, although it should be appreciated that more than one reference pin 80 may be used to properly register the electronic device 70 with the web 140. Further, although the reference slots 244a, 244b are shown generally along a midline of the web 140, it should be appreciated that the reference slots 244a, 244b and the reference pins 80 may be located in any locations suitable for properly registering the electronic device 70 with the web 140.
Alternatively, the electronic device 70 may be registered with the web 140 through the use reference markers utilizing autocalibration techniques. For example, the web 140 may include autocalibration markers 144a-d that are used in conjunction with complementary markers 81a-d on the electronic device 70. The concept is to site the electronic device 70 on the web 140 so that each complementary marker 81a-d on the electronic device 70 is sited within a respective autocalibration marker 144a-d on the web 140.
FIG. 7 illustrates an alternative selective deposition assembly 310. The selective deposition assembly 310 includes a web 40 for transporting the electronic devices 70 and web 240 that includes openings in a similar fashion as the web 140. The electronic devices 70 can be built on web 40 beforehand, such that the web 40 acts as a substrate for the electronic devices 70, or can be affixed to the web 40 with an adhesive 90. The web 240 serves as a shadow mask to inhibit coating certain portions of the electronic devices 70, namely the electric contacts 77, 79. The web 240 can be appropriately registered relative to the electronic devices 70 by altering the velocity of the web 240 relative to the velocity of the web 40.
It should be appreciated that the coating on the electronic devices 70 may be similar to the graded barrier coating used on the substrates 72 as described with reference to FIG. 2. Alternatively, the coating on the electronic devices 70 may be a hard coating designed to protect the electronic devices 70 from ultraviolet radiation or from physical or chemical attack, such as scratches and abrasion. Such suitable hard coatings may include, for example, coating compositions that include at least one resin. The resin can be an epoxy-based resin. For example, the resin can be a cycloaliphatic resin. The resin can also be an acrylic-based resin. Some epoxies may impart increased surface durability. A siloxane portion of certain diepoxies may be easily adjusted in length and branching to optimize desired properties. The hard coating composition may further include at least one flexibilizing agent, adhesive agent, surfactant or catalyst and combinations thereof. In still another aspect, the hard coating composition may be cured. The curing may be radiation curing, such as ultraviolet curing, or thermal curing and combinations thereof. Other curing mechanisms can also be employed in place of UV curing, including anhydride or amine curing. Additives can be incorporated into the leveling layer to tailor its properties. For example, a UV catalyst may be added to the layer composition. In another example, UV absorbers can be added to protect underlying UV sensitive layers. Siloxane additives can be included to make the leveling layer more scratch resistant. Antioxidant chemicals such as Irganox®, manufactured by the Geigy Chemical Corporation, hinder amine complexes and can also be added to prevent yellowing of the coating and underlying substrate. Further discussion of suitable hard coating materials, suitable coating compositions and suitable coating thickness may be found in US patent publication number US 2006/0001040.
The selectively coated electronic devices 70 may be removed from the selective coating assembly through the use of the web 40, 140 or through the use of a mechanism for moving individual electronic devices 70. Examples of such a mechanism include a vacuum chuck, a claw, or adhesive tape.
While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. For example, although the electronic device 70 has been described with reference to an OLED device, it should be appreciated that any suitable electronic device may be used that requires encapsulation or coating on some but not all portions. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
Patent Application
20080092814
