The present application relates to a deposition arrangement.
The present application further relates to a method for depositing
US2011/0065282 pertains to an apparatus for applying a patterned coating to an OLED substrate in a continuous roll-to-roll vapor based deposition process. The apparatus comprises a vapor deposition source, a processing drum, a drive roller, and a shadow mask wherein the shadow mask comprises a mask line feature that selectively prevents deposition of the coating onto the substrate. The mask line features are positioned parallel to the moving direction of the OLED substrate. The shadow mask also comprises one or more beam features, which are positioned perpendicular to the moving direction of the OLED substrate and provide mechanical support to the line features. These beam features serve to prevent the mask line features from deformation related to thermal or mechanical stress. The known apparatus is suitable to deposit mutually spaced coating bands that extend in a longitudinal direction of the substrate. It is a disadvantage that the apparatus is not suitable to deposit features that are bounded in the longitudinal direction.
It is an object of the present invention to provide a deposition arrangement and a deposition method that are improved in that they enable a more wide variety of patterns to be deposited while providing for an adequate support of the shadow mask.
According to a first aspect of the invention a deposition arrangement as claimed in claim 1.
According to a second aspect of the invention a deposition method is provided as claimed in claim 17.
Amongst others, the deposition mask in the deposition arrangement and as used in the deposition method is provided with a spatial pattern defined by at least one closed area and at least one perforated area defined by a plurality of through holes. Furthermore, a substrate carrier is provided to carry the substrate with its substrate surface at distance from the second mask surface.
In this deposition arrangement and deposition method it is rendered possible to deposit patterns that could previously not be achieved with a single metal plate as the deposition mask. For example the substrate area that is kept free from deposited substance within the character “e” requires a corresponding closed area in the deposition mask. The area of the substrate surface surrounding this substrate area that should be permeable to the substance to be deposited. This would require however that the closed area of the deposition mask is no longer connected to the remainder of the mask. In the deposition arrangement and deposition method according to the present invention the area permeable for the substance is provided as a perforated area. On the one hand this allows the deposition substance to pass forward to the substrate surface. At the same time it supports the closed areas contained inside. As the substrate carrier is provided to carry the substrate with its substrate surface at distance from the second mask surface, the deposition patterns resulting from the individual through holes in a perforated area overlap mutually, so that the pattern of the individual through holes is not visible (or to a limited extent) in the pattern formed by the substance deposited on the substrate surface.
As the substrate carrier carries the substrate with its substrate surface at distance from the second mask surface, it is achieved that the substance is deposited according to a spatial pattern that corresponds to the spatial pattern defined by the at least one closed area and at least one perforated area of the deposition mask. I.e. the at least one closed area corresponds to an at least a first area on the first substrate surface that is isomorphic with the at least one closed area of the deposition mask and the at least one perforated area corresponds to an at least a second area on the first substrate surface that is isomorphic with the at least one perforated area of the deposition mask.
Therein the at least a first area is substantially free from deposited substance and the at least a second area is provided with a layer of the substance. Due to the fact that substrate carrier carries the substrate with its first substrate surface at distance from the second mask surface, it is achieved that the deposited layer in the at least a second area is substantially homogeneous. A substantially homogeneous layer is understood to be a layer wherein the thickness variations are less substantially less that the average variation of the thickness of the deposited layer. More in particular the difference between the smallest and the largest thickness is less than 50% of the average thickness. Preferably the difference between the smallest and the largest thickness is less than 20% of the average thickness, or even less than 10% of the average thickness.
In an embodiment the deposition mask is provided with a curve shaped form and the substrate carrier carries the substrate with its substrate surface conformally to the second mask surface. Therewith the deposition mask can have an increased structural integrity.
In particular, the deposition mask may be provided as a cylindrical body and the deposition source may be arranged inside the cylindrical body. This allows for a very efficient implementation in a roll to roll arrangement. The roll to roll arrangement in this implementation may for example comprises an actuator for rotating the cylindrical body at an angular velocity, and the transport facility may be arranged to transport the substrate with its substrate surface along a cylindrical trajectory in an at least substantially coaxial manner with respect to the second mask surface wherein the substrate when being transported along said cylindrical trajectory moves with the same angular velocity along the deposition surface. In this embodiment a continuous deposition process is enabled.
In an embodiment the substrate carrier is formed by a pair of support rolls that are arranged at respective lateral sides of the deposition mask, which support rolls have an outer diameter greater than an outer diameter of the deposition mask. In most cases this suffices to properly align and position the substrate with the deposition mask. If desired, the support rolls may be combined with complementary support means, such as complementary support rolls or complementary support belts.
These and other aspects are described in more detail with reference to the drawing. Therein:
Like reference symbols in the various drawings indicate like elements unless otherwise indicated.
In an embodiment the deposition mask 30 has a thickness ΔD in a range of about 2 micron to about 500 micron. It is expected that a thickness ΔD that is substantially smaller than 2 micron, e.g. 1 micron, or 0.5 micron, will result in an insufficient rigidity of the deposition mask. In case the thickness ΔD is substantially larger than 500 micron, e.g. 1 mm or 2 mm, would have the effect that a relatively large amount of the evaporated substance is deposited on the walls of the through holes 37.
Preferably the thickness ΔD of the deposition mask 30 is in the same order of magnitude as the diameter of the through holes. For example the thickness may be in a range of 0.2 to 5 times a diameter of the through holes.
In an embodiment the through holes 37 have a diameter in the range between 10 and 100 micron. Accordingly, a deposition mask having through holes with a diameter in the lower range preferably have a thickness in the range of 2 to 100 micron, whereas a deposition mask having its through holes with a diameter in the higher range preferably have a thickness in the range of 20 to 500 micron.
In some applications the through holes 37 may be tapered. For example, the through holes may taper outwards with a direction a towards the deposition source as illustrated in
The permeability is defined as the fraction occupied by through holes in the perforated area. A permeability in the range of 10% to about 50% has been found most suitable. In case the permeability is substantially less than 10%, e.g. 5% in practice an insufficiently homogeneous deposition is achieved. If the permeability is substantially greater than 50%, e.g. more than 70% the structural integrity of the deposition mask 30 is at stake. In most practical implementations the permeability may be in a range of 15 to 30%, e.g. in the range of 20 to 25%, e.g. 21%. In case the through holes are tapered, the fraction occupied by the through holes is larger on the side of the deposition mask where the through holes are tapered outward. In that case the permeability on the side where the through holes are tapered outward should preferably meet an upper boundary as indicated here for the permeability, e.g. 50%, 30%, or 25%. The permeability on the opposite side of the deposition mask should preferably meet the lower boundary, e.g. 10, 20 or 30%.
In most circumstances the substrate carrier 10 may carry the substrate ST with its surface ST1 at a distance D from the second mask surface 39 such that the distance is in a range of 0.5 to 5 times an average distance dh between subsequent through holes. In some circumstances, the distance D may be larger. For example if a sharp transition between features in the deposition pattern on the substrate surface ST1 is not required, or if a smooth transition is desired, the distance D may be even 10 or 20 times the average distance dn. This may also be the case if the thickness ΔD of the deposition mask is relatively large as compared to the diameter of the through holes, e.g. if the thickness ΔD of the deposition mask is more than 5× a diameter of the through holes. In other cases the distance D may be smaller than the minimum indicated above. For example if the deposition source 20 has a relatively large area, the distance D may be somewhat smaller, e.g. 0.2 times an average distance dh between subsequent through holes.
As used herein, the term “substrate” has its usual meaning in materials science as an object comprising a surface on which processing is conducted, in this case layer deposition. In this context, for example the production of flexible electronics, the substrate typically comprises a foil. The term “foil” refers to a sheet comprising one or more layers of material. There can be structures on the foil on which the mask might be aligned too. The foil is flexible such that it can be used in a roll-to-roll (R2R) manufacturing process. For such purpose, a foil may be considered flexible if it can be rolled or bent over a radius of curvature of 50 cm or less, e.g. 12 cm. Alternatively, or in conjunction a foil may be considered flexible if it has a flexural rigidity smaller than 500 Pa·m{circumflex over ( )}3. Materials suitable for as the foil, or as a layer for the foil are for example polymers, such as PET, PEN or PI. Also thin glass can be a suitable substrate material. Alternatively, metals may be used for this purpose, such as aluminum, steel or copper. The foil may for example have a thickness in the range of 1 micron to 1 mm depending on the required strength and flexibility. For other purpose also more rigid substrates may be considered, e.g. glass plates. Experiments were conducted with a deposition mask with a spatial pattern having closed areas 34 and perforated areas 36. The perforated areas are defined by a plurality of through holes 37. The perforated areas 36 define the areas of the substrate surface ST1 to be provided with a substantially continuous layer of the deposited substance and the closed areas define the areas of the substrate surface ST1 to remain free from the substance. A portion of a perforated area 36 of the deposition mask 30 is illustrated in
However, alternatively, as illustrated in
The deposition mask having the perforated area 36 as shown in
By way of example a first spatial pattern was applied in the form of a set of lines having a stepwise diminishing with. The first line of this pattern has a width of 1000 micron, the second one a width of 500 micron, the third one of 200 micron and so on. According the perforated area 36 in the first line has about 10 neighboring holes in the direction of the width of the line, the second one about 5 and so on.
The processed substrate STa, so obtained is shown in
The deposition arrangement with this deposition mask makes it possible to deposit patterns that could previously not be achieved with a single metal plate as the deposition mask. For example the substrate area that is kept free from deposited substance within the character “e” requires a corresponding closed area in the deposition mask. The area of the substrate surface surrounding this substrate area that should be permeable to the substance to be deposited. This would require however that the closed area of the deposition mask is no longer connected to the remainder of the mask. In the deposition arrangement according to the present invention the area permeable for the substance is provided as a perforated area, that on the one hand allows the deposition substance pass forward to the substrate surface, and that on the other hand supports the closed areas contained inside.
In embodiments the deposition mask may comprise fully open areas in addition to closed areas and perforated areas. For example for deposition of the pattern illustrated in
A schematic overview of the arrangement is presented in
The deposition arrangement shown in
In the embodiment of
To keep the substrate surface ST1 conformal to the second mask surface 39 at a distance D to the second mask surface the support rolls 70, 72 have an outer diameter that is 2D larger than the outer diameter of the deposition mask. One or both of the support rolls may have a central opening, e.g. be formed as a hollow cylinder and have an outer bearing, so that interior parts of the arrangement, such as the deposition source are easily accessible for service purposes for example. The arrangement of the deposition mask 30 as a curved shape further increases mechanical stability in addition to the mechanical stability that is provided by the presence of perforated areas as a replacement for fully open areas in the deposition mask. In particular a very stable mechanic structures is obtained in that the deposition mask 30 is provided as a cylindrical body. The deposition source 20 is arranged inside the cylindrical body.
The embodiment of the deposition arrangement of
For a relatively thin substrate the support by only the support rolls 70, 72 may be insufficient to maintain the substrate properly aligned with the deposition mask 30.
In an embodiment, alternatively or additionally tenter frame technology may be used. Therein two closely spaced endless chains with substrate holding clips are provided to keep the substrate on a controlled distance from the deposition mask. The substrate holding clips may cooperate with perforations in the substrate. Examples thereof are described in U.S. Pat. Nos. 650,385, 2,584,553 and 4,403,379.
A still further embodiment is shown in
In the embodiment of
In the version of
In particular it can be seen in the top view of
The complementary support rolls 70a, . . . , 70n are preferably aligned with their associated support roll 70. Likewise the complementary support rolls 72a, . . . , 72n are preferably aligned with their associated support roll 72. In the arrangement of
It is noted that the same principle is applicable to the embodiment shown in
In this arrangement the deposition source 20 is arranged inside the loop formed by the endless belt 370. The endless belt 370 is guided on mutually opposite lateral sides by a respective belt guide roll 372 and complementary belt guide rolls 374a, 374b, 374c, . . . , 374n. The substrate ST is carried by a substrate carrier roll 49 at a predetermined distance D from the second surface 39 of the deposition mask. The guide roll 372 and complementary belt guide rolls 374a, 374b, 374c, . . . , 374n, leave free the deposition mask 30 in the central zone of the endless belt 370, so that substance SB can reach the first surface ST1 of the substrate via the deposition mask. The deposition mask 30 in the deposition arrangement is provided with a spatial pattern defined by at least one closed area and at least one perforated area defined by a plurality of through holes. As the substrate carrier roll 49 carries the substrate with its substrate surface at distance from the second mask surface 39, it is achieved that the substance SB is deposited according to a spatial pattern that corresponds to the spatial pattern defined by the at least one closed area and at least one perforated area of the deposition mask. I.e. the at least one closed area corresponds to an at least a first area on the first substrate surface that is isomorphic with the at least one closed area of the deposition mask. The at least one perforated area corresponds to an at least a second area on the first substrate surface that is isomorphic with the at least one perforated area of the deposition mask.
Therein the at least a first area is substantially free from deposited substance and the at least a second area is provided with a layer of the substance. Due to the fact that substrate carrier roll 49 carries the substrate ST with its first substrate surface ST1 at distance D from the second mask surface 39, it is achieved that the deposited layer in the at least a second area is substantially homogeneous. A substantially homogeneous layer is understood to be a layer wherein the thickness variations are less substantially less that the average variation of the thickness of the deposited layer. More in particular the difference between the smallest and the largest thickness is less than 50% of the average thickness. Preferably the difference between the smallest and the largest thickness is less than 20% of the average thickness, or even less than 10% of the average thickness.
It is an advantage of this embodiment that the mechanical load of the substrate ST during processing is minimal. This is of particular advantage for very thin substrates, e.g. having a thickness in the range of 1 to 10 micron.
Number | Date | Country | Kind |
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16179871.5 | Jul 2016 | EP | regional |
Filing Document | Filing Date | Country | Kind |
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PCT/NL2017/050480 | 7/17/2017 | WO | 00 |