Method for forming oleds using photolithography

Abstract

A method for making OLED displays, comprising a first step of providing a substrate with bottom electrode segments separated by a pixel definition layer; a second step of uniformly forming at least an OLED materials layer for emitting a first color, a top electrode, and a horizontal encapsulation layer; a third step of patterning a protective block over one set of bottom electrode segments; a fourth step of selectively removing the OLED materials layer, top electrode and horizontal encapsulation layer over the bottom electrode segments without the protective block; a fifth step of uniformly forming a vertical encapsulation layer over all surfaces; and a sixth step of selectively removing only the horizontal portions of the vertical encapsulation layer along with the protective block to create a fully encapsulated pixel over the set of bottom electrode segments that were protected by the protective block.

Description

[0001] Title

[0002] METHOD FOR FORMING OLEDs USING PHOTOLITHOGRAPHY Cross Reference to Related Applications

[0003] This application claims the benefit of U.S. Provisional Application No 63 / 749,562 filed January 25, 2025 under Attorney Docket OLWK-0032-USP.

[0004] Background

[0005] OLED (Organic Light-Emitting Diodes) technology has many advantages for all types of display applications. It is self-emissive, has excellent image quality, is very efficient, and has an ultra-high color rendition and wide color space. Self-emissive OLED devices have the important advantage over backlight devices (such as LCD) in that each pixel only produces the intensity required by the image, whereas backlighted pixels produce maximum intensity followed by absorption of the unwanted light.

[0006] The manufacture of OLED displays can be very complicated since it is necessary to pattern the device into pixels which emit different colors. One general approach that is typically simpler to manufacture is to coat common OLED layers over bottom electrode segments and use color filters to achieve the desired color for each pixel. However, there are problems with this approach including increased cross-talk between neighboring pixels due to the higher voltage required by more OLED stacks (which reduces color reproduction) and light absorption by the color filters (which reduces overall efficiency). Another general approach is to directly form individual pixels, where each pixel has different OLED materials to produce a desired color. This approach greatly reduces the cross-talk problem (because the OLED layers are not common across all pixels) and avoids the need for color filters (thereby increasing efficiency by reducing light absorbance). However, this approach requires that the OLED materials for each pixel are deposited only in the desired locations, which greatly complicates the manufacturing process.

[0007] In displays where each pixel is individually formed, the pixels are typically kept separate by the presence of dividing structures such as banks or dams which extend vertically from the substrate and contain the OLED materials within the pixel. These are often called pixel definition layers (PDLs). Such banks or dams are typically composed of non-conductive, non-emitting materials and are permanent features of the device. Such structures can be formed prior to the deposition of the OLED materials via vapor deposition using masks or via photolithography. However, for many applications, vapor deposition / maskscannot provide the necessary resolution since the pixels may be very small. Moreover, it is still necessary to deposit the desired OLED material within a specific pixel. Wet methods of depositing such as ink-jet can be used for this purpose but may not be suitable for all OLED materials and the deposition may not be uniform due to wetting effects along the side walls of the dividing structures.

[0008] It would be desirable from a manufacturing standpoint to use photolithography to directly form pixelated devices by depositing the OLED material uniformly, particularly via vapor deposition, without the need for any masks. Photolithography is a well-known process (see https: / / en.wikipedia.org / wiki / Photolithography). Such an approach would require the removal of photoresist and OLED materials from unwanted areas. This can be problematic for a number of reasons.

[0009] As a theoretical comparative example to highlight potential problems, Figs. 1 A-10 illustrate one possible way to use photolithography to create a pixelated OLED display using known methods. In Fig. 1 A, three bottom electrode segments 3, 3’and 3” are patterned over a substrate 1. Fig. IB shows the next step of uniformly overcoating the substrate with negative photoresist 5A and shows which areas will and will not be exposed to hv (radiation or light). Fig. 1C shows the result of exposure by hv of the photoresist (5A) everywhere except over electrode segment 3. This creates hardened photoresist 5B everywhere except in the unexposed area over electrode segment 3, which remains unhardened. The unhardened photoresist 5A over electrode segment 3 is then removed to expose the electrode’s upper surface as shown in Fig. ID. Next, Fig. IE shows the deposition of a 1stOLED material 7 uniformly over the entire surface. Fig. IF shows the next step where the hardened photoresist 5B is removed along with the overlying OLED material 7, leaving only the OLED material 7 over the bottom electrode segment 3. Figs. 1G-1 J repeat the process in a similar way in order to create a layer of a 2ndOLED material 9 over a different electrode segment 3’. Similar operations (Figs. 1K-1N) can then be used to create a layer of a third OLED material 11 over the third electrode segment 3”. Fig. 10 shows the final steps where the gaps between the OLED pixels are filled with non-conductive material 12, a common top electrode 13 is added and then covered by a common encapsulation layer 14.

[0010] In this way, it is possible to use photolithography to create a pixelated OLED.

[0011] However, there are a number of steps involved that are difficult, if not impossible, to be performed satisfactorily. For example, the steps shown in Figs. IF, 1 J and IN require conditions that would selectively remove hardened photoresist / OLED material without removing or affecting the performance of the OLED material over the electrode. Similarly,the steps shown in Figs. 1G and IK require that the photoresist be overcoated on the previous OLED materials without any adverse effects on its performance. The OLED materials are often adversely affected by the wet methods for removing photoresist so dry etching is typically used. Dry etching can be restricted to specific areas and so, can be used to create patterns. However, dry etching can leave residual ash and decomposition products that can affect later steps and it can expose the OLED to any subsequent processes that do not include a passivation of OLED sidewalls

[0012] There are ways that have been proposed in order to use photolithography to manufacture pixelated OLED displays. Such processes are often described as being ‘maskless’ since the deposition of the OLED materials do not require shadow masks for patterning the deposits of OLED materials on the surface of a substrate. For example, see the following references:

[0013] Shiomi, Naoki, et al. "17-1: Invited Paper: Development of the Novel eLEAP™ AMOLED Display with Breakthrough Panel Performance." SID Symposium Digest of Technical Papers. Vol. 54. No. 1. 2023.

[0014] Eguchi, Shingo, et al. "17-3: An 8.3-inch 1058-ppi OLED Display with Side-by-Side Pixel Structure Fully Fabricated by Photolithography." SID Symposium Digest of Technical Papers. Vol. 54. No. 1. 2023.

[0015] Xiao, Yiming, et al. "17-2: Development of Visionox intelligent Pixelization (ViPTM) Technology in AMOLED Applications." SID Symposium Digest of Technical Papers. Vol. 54. No. 1. 2023.

[0016] Xiao, Yiming, et al. "27-3: Progress in High-Performance AMOLED Display with ViP™ Technology." SID Symposium Digest of Technical Papers. Vol. 55, No SI, 2024.

[0017] Xiao, Yiming, et al. "69-1: Invited Paper: Recent Progress in High-Performance AMOLED Display with ViPTM Technology." SID Symposium Digest of Technical Papers. Vol. 55. No. 1. 2024.

[0018] Ke, Tung-Huei, et al. "11-2: Technology Developments in High-Resolution FMM-free OLED and BEOL IGZO TFTs for Power-Efficient Microdisplays." SID Symposium Digest of Technical Papers. Vol. 52. No. 1. 2021.

[0019] Ke, Tung-Huei, et al. "59-1: Invited Paper: Scaling Down of OLED Pixels Enabled by Photolithography." SID Symposium Digest of Technical Papers. Vol. 53. No. 1. 2022.

[0020] Ke, Tung-Huei, et al. "55.1: Invited Paper: FMM-free OLED Manufacturing Enabled by Photolithographic Patterning Processes." SID Symposium Digest of Technical Papers. Vol.

[0021] 52., No S2, 2021.WO2015 / 144930 describes a method for producing side-by side OLEDs using a maskless photolithography process. The method comprises: depositing a first interlayer on the substrate; patterning the first interlayer, thereby removing the first interlayer at the first location; depositing a first device layer; depositing a second interlayer; patterning the second interlayer and the underlying layers, thereby removing the second interlayer and the underlying layers at the second location; depositing a second device layer; and afterwards patterning the first device layer and the second device layer to form the first patterned device layer at the first location and the second patterned device layer at the second location.

[0022] USll,309,529B2 describes a process where a substrate with segmented bottom electrodes is overcoated with a uniform layer of OLED materials (presumably of a first color), then overcoated with a fluorinated “lift-off’ material as well as a fluorinated photoresist which is then patterned to form an opening to the OLED material over a first electrode segment. Then the OLED material over the electrode segment is removed, the surface of the electrode is cleaned and then, another OLED material (presumably of a second color) is deposited over the entire surface. Then the lift-off layer and photoresist are removed, leaving a surface with two sections of different OLED materials (one over the first electrode and the other over the rest of the device, including second and third electrode segments). This process is repeated once more to produce a 2nd region of OLED materials (presumably of a third color) over a second electrode segment. The initial OLED materials are left over the third electrode segment. This creates a 3-color device that requires only 2 lift-off steps in addition with the photoresist patterning / cleaning / deposition / removal steps.

[0023] Summary

[0024] A method for making a pixelated OLED displays using photolithography without the need for patterning or masking for the deposition of OLED materials has been developed. The method for making pixelated OLED displays comprises: a first step of providing a substrate with a pattern of bottom electrode segments, each of which are separated by a pixel definition layer; a second step of uniformly forming at least an OLED materials layer for emitting a first color, a top electrode, and a horizontal encapsulation layer over all of the bottom electrode segments and pixel definition layer; a third step of patterning a protective block over one set of bottom electrode segments but not over the other sets of bottom electrode segments; a fourth step of selectively removing the OLED materials layer, top electrode and horizontal encapsulation layer over the other sets of bottom electrode segments without the protective block; a fifth step of uniformly forming a vertical encapsulation layer over all surfaces; and a sixth step of selectively removing only the horizontal portions of thevertical encapsulation layer along with the protective block while retaining the vertical portions of the vertical encapsulation layers to create a fully encapsulated pixel that emits a first color over the set of bottom electrode segments that were protected by the protective block in the third step and where the other sets of bottom electrode segments that were not protected by the protective block in the third step are exposed.

[0025] The above method wherein steps seven to eleven are added after the sixth step by repeating steps two to six except for using an OLED materials layer for emitting a second color and forming a protective block over a second set of exposed electrode segments to create fully encapsulated pixels that emit a second color over the bottom electrode segments protected by the protective block during the repeated steps.

[0026] The above method wherein steps twelve to sixteen are added after step eleven by again repeating steps two to six except for using an OLED materials layer for emitting a third color and forming a protective block over the remaining set of exposed electrode segments to create fully encapsulated pixels that emit a third color over the bottom electrode segments protected by the protective block during the repeated steps.

[0027] Any of the above methods wherein in the fifth step, the vertical encapsulation layer is formed using an RIE-ICP process. The vertical encapsulation layer can be a fluorocarbon. The fluorocarbon can be derived from a fluorocarbon precursor with 4 or less carbon atoms. The fluorocarbon precursor can include CF4, C2F4, C2F6, C3F6, C3F8, C4F8 or C4F10.

[0028] Any of the above methods wherein the removal of the horizontal portions of vertical encapsulation layer and the protective block uses an anisotropic RIE-ICP process using O2.

[0029] Any of the above methods where the step of selectively removing the OLED materials layer, top electrode and horizontal encapsulation layer further comprises a two-stage process where a first stage is removing the horizontal encapsulation layer and top electrode and a second stage is removing the OLED materials layer.

[0030] The above method wherein first stage to remove the horizontal encapsulation layer and top electrode can use an RIE-ICP process. The RIE-ICP process of the first stage can use CCI4+BCI3 with or without argon. The RIE-ICP process of the first stage can also be divided into two phases, wherein the first phase uses CF4+CHF3+O2 with or without argon and the second phase uses CCI4+BCI3 with or without argon. The above method wherein the second stage of removing the OLED materials layer can use a RIE-ICP process using SF6 with or without 02, CF4, or argon in any combination.

[0031] Any of the above methods wherein the step of uniformly forming an OLED materials layer(s) is by vapor deposition.Any of the above methods wherein the protective block is formed of a hardened photoresist.

[0032] It would be desirable to develop a manufacturing process for OLED displays that uses photolithography to pattern OLED materials into individual pixels and does not require the use of masks. In particular, it is important that the removal of materials in undesired locations can be accomplished without damaging already deposited OLED materials.

[0033] Brief Description of the Drawings

[0034] Figs. 1 A-1O illustrate a theoretical comparative example of a way to use photolithography to create a pixelated OLED display.

[0035] Fig. 2 is a box flow-chart of the individual steps for a method of making a full-color pixelated OLED using photolithography.

[0036] Figs. 3A-3S show cross-sections of the device at each individual step as listed in Fig-2.

[0037] Figs. 4A1 (cross-section view) and 4A2 (overview view) show an embodiment of an OLED device at a step corresponding to step 3 A.

[0038] Figs. 4B1 (cross-section view) and 4B2 (overview view) show an embodiment of an OLED device at a step corresponding to Fig. 3G.

[0039] Figs. 4C1 (cross-section view) and 4C2 (overview view) show an embodiment of an OLED device at a step corresponding to Fig. 3M.

[0040] Figs. 4D1 (cross-section view) and 4D2 (overview view) show an embodiment of an OLED device at a step corresponding to Fig. 3S.

[0041] Fig. 5 shows an embodiment where the external contact pads for the top electrode are electrically connected together outside of the encapsulation after completion of the device shown in Figs. 4D1 and 4D2.

[0042] Fig. 6A-6F shows an embodiment of the method to create a pixelated OLED layer with common top electrode and encapsulation layers.

[0043] The Figures are not necessarily shown in the correct relative scale.

[0044] Description

[0045] For the purposes of this disclosure, the terms “over” or “above” mean that the structure involved is located over and above another structure, that is, on the side further or opposite from the substrate. Likewise, the terms “below” or “under” mean that the structure involved is located beneath another structure, that is, on the side closer to the substrate.

[0046] “Uppermost”, “upper” or “top” refers to a side or surface furthest from the substrate while “bottommost”, “lower” or “bottom” refers to the side or surface closest to the substrate.Unless otherwise noted, “over” or “under” should be interpreted as either that the two structures may be in direct contact or there may be intermediate layers between them. By “layer”, it should be understood that a layer has two sides or surfaces (an uppermost and bottommost) and that multiple layers could be present and is not limited to a single layer. The terms ‘horizontal’ or “width” refer to a direction or plane that is parallel to the plane of the substrate whereas “vertical” or “thickness” refer to a direction or plane that is orthogonal or perpendicular to the plane of the substrate. It should be noted that “horizontal” and “vertical” surfaces may only be substantially oriented in those directions and may have small portions that have a different orientation than the bulk of the surface. An “edge” of a layer is along the vertical or thickness dimension. R refers to red light, G refers to green light, B refers to blue light and W refers to white light. By ‘maskless’, it is meant that that the process does not require masking or patterning of the organic materials in the active emissive areas, and not that every step of the entire process does not require masking. For example, a mask with a large opening equal to the size of the entire active area of the display may be used to protect peripheral areas of the display from deposition. It may be that some steps, other than the vapor deposition of the organic materials, use masking to pattern a layer. Patterning refers to forming or organizing an arrangement of something into a predetermined pattern in certain locations. mTorr (millitorr) is a unit of pressure that is equal to 0.001 Torr, which is used for measuring very low pressures, particularly in high vacuum applications. One millitorr is approximately equal to 0.133322 pascals.

[0047] Reactive-ion etching (RIE) is an etching technology used in microfabrication (see https: / / en.wikipedia.org / wiki / Reactive-ion_etching). RIE is a type of dry etching which has different characteristics than wet etching. RIE uses chemically reactive plasma to remove material deposited on wafers. The plasma is generated under low pressure (vacuum) by an electromagnetic field. High-energy ions from the plasma attack the wafer surface and react with it. A variant is a RIE-ICP process where the plasma can be generated by an inductively coupled plasma (ICP) process (see https: / / en.wikipedia.org / wiki / Inductively_coupled_plasma). This is a type of plasma source in which the energy is supplied by electric currents which are produced by electromagnetic induction, that is, by time-varying magnetic fields. In general, RIE offers several significant benefits that make it indispensable in microfabrication: it allows for exact control over etching depth and profile, essential for creating features at the nanoscale; it allows for anisotropic etching and can achieve highly directional etching which is crucial for applications requiring sharp, vertical sidewalls; it is compatible with a wide range ofmaterials, including silicon, silicon dioxide, silicon nitride, and various metals and polymers; and the highly controlled environmental conditions allows for consistent results. Another advantage of RIE-ICP process is the ability to etch in a low-pressure environment (~ 15 to 50 mTorr) while maintaining plasma. The low pressure increases the anisotropy of the etch. These low pressures cannot be achieved by a standard RIE process (> 50 mTorr).

[0048] There is a general need for a manufacturing process for OLED displays that uses photolithography to pattern OLED materials into individual pixels and does not require the use of masks during the deposition of the OLED materials. This is a particular need when using vacuum or vapor deposition of the OLED materials since these processes typically require masks. The steps of an example of such a ‘maskless’ process are listed in the box diagram of Fig. 2. In particular, the formation of a pixelated three-color OLED display generally involves the steps (in order) of:

[0049] 1) Providing a display substrate with patterned bottom electrode segments separated by a PDL (Pixel Definition Layer).

[0050] 2) Uniformly depositing (without masking) over the entire substrate in order: an OLED materials layer that will emit a first color, optionally followed by a top electrode, followed by a horizontal encapsulation layer.

[0051] 3) Patterning a protective block (layer) over some electrode segments, but not all electrode segments. The set of protected electrode segments (which are covered by the OLED material layers of a first color, top electrode (if present) and horizontal encapsulation layer) will eventually become the pixels of a first color in the final display.

[0052] 4) Removing the horizontal encapsulation layer, top electrode (if present) and OLED layers in any area not protected by the patterned protective block.

[0053] 5) Uniformly depositing a vertical encapsulation layer over the entire substrate formed in the previous steps including all horizontal and vertical surfaces.

[0054] 6) Selectively removing only the horizontal portions of the vertical encapsulation layer along with the entire protective block while retaining the vertical portions of the vertical encapsulation layer to create a fully encapsulated pixel of a first color. Those electrode segments not protected by the protective block in step 4 are fully exposed.

[0055] 7) Repeating Steps 2 through 6, first with OLED materials that will emit a second color over a second set of electrode segments, and then repeating Steps 2 through 6 again with OLED materials that will emit a third color over the remaining electrode segments, in order to create a fully encapsulated 3-color pixelated OLED display.Some important features of the process generally described in Fig. 2 include the following:

[0056] 1) The process by which the OLED layers, top electrode (if present) and encapsulation are removed from areas not protected by protective block must not affect in any substantial way the protective block that lies over the fully encapsulated pixel below it.

[0057] 2) The removal of the OLED layers, top electrode (if present) and horizontal encapsulation layer in unwanted areas (i.e. those that lie outside the protective block) exposes the edges of the (previously) fully encapsulated pixel under the protective block. These exposed edges are along a substantially vertical edge directly below the edge of the protective block. The exposure of the edges of the OLED layers under the protective block provides an undesirable pathway for oxygen and moisture to enter the pixel.

[0058] 3) In order to re-establish full encapsulation of the pixel, a vertical encapsulation layer is deposited over the vertical edges of the OLED materials layer below the side of the protective block, thus re-encapsulating the pixel under the protective block. Thus, the devices prepared using this method have two different encapsulation structures; a first (the horizontal encapsulation layer) that covers the horizontal surfaces of the OLED pixels and a second, (the vertical encapsulation layer) that covers the exposed vertical edges of the OLED that are formed when the undesired portions are removed.

[0059] 4) The protective block can be formed of hardened photoresist and patterned using photolithography over only selected OLED pixels that are fully encapsulated.

[0060] Figs. 3A-3S are cross-sections that further show some of the details and requirements of the method generally described in Fig. 2 to create an OLED display with fully encapsulated pixels without the need for masking or patterning of the OLED materials.

[0061] Fig. 3 A is the first step where a suitable substrate 10 with a pattern of three sets or groupings of individual bottom electrode segments 30, 30’, 30” that are separated by a permanent pixel definition layer (PDL) 50 is provided.

[0062] Fig. 3B is a second step where the patterned substrate as in Fig. 3 A is overcoated uniformly via vapor deposition (no masks or patterning) with a layer or layers of suitable OLED materials to form an OLED materials layer 70. This layer will be in direct contact with all electrode segments (30, 30’ and 30”). Included at this stage can be a subsequent optional step where the OLED materials layer 70 is then further overcoated uniformly via vapor deposition (no masks or patterning) with a top electrode 80. Although optional, it is preferred that the top electrode 80 is included. This is followed by the uniform vapor deposition (no masks or patterning) of a horizontal encapsulation layer 90. After completion of this step, theOLED is fully encapsulated and would be operational (assuming the top electrode is present) in the areas over the bottom electrode segments and not over the PDL. However, since all of these layers that emit a first color of light are coated uniformly (no masking or patterning) over the entire surface of the substrate, they are also located over the other bottom electrode segments 30’ and 30” as well as 30. Since bottom electrode segments 30’ and 30” will eventually correspond to pixels that emit colors that are different from the first color (according to the pixel defined by bottom electrode 30), the completed OLED must be removed from these areas.

[0063] Fig. 3C shows a third step where a photoresist has been deposited uniformly over the surface of the entire substrate as shown in Fig. 3B, and hardened by selective irradiation only in the area over one set of the bottom electrode segments (in this example, 30) and processed to create a protective block 100 of residual hardened photoresist over the electrode segments 30 with the remainder of the photoresist removed over 30’ or 30” (the other two sets of electrode segments). At this stage, all of the electrode segments have been overcoated with layers 70, 80 (if present) and 90 but only a selected number will have the protective photoresist block and the others will not. The organic layers in OLED pixel 30 will be unaffected by the formation of the overlying photoresist block 100 since it is fully encapsulated by horizontal encapsulation layer 90.

[0064] Fig. 3D shows a first stage of the fourth step where the horizontal encapsulation layer 90 and the top electrode 80 are removed via dry etching in the locations not protected by the photoresist 100. In this embodiment, the OLED materials layer 70 is not removed during this step. It should be noted that the etching could slightly reduce the size (or change the shape) of the exposed PDL surface, but that the PDL would still function as intended.

[0065] Fig. 3E shows a second stage of the fourth step where the OLED materials layer 70 is removed in the areas not protected by the photoresist 100 using a second dry etch.

[0066] After the steps shown in Figs. 3D and 3E are completed, the region according to the first set of pixels defined by bottom segment 30 is covered (and protected) by hardened photoresist 100 while the remaining surface (the other sets of bottom electrode segments 30’ and 30” and the separating PDL segments 50) are uncovered by any materials. The steps shown in Figs. 3D and 3E may be combined into a single dry etch process so long as the photoresist layer 100 prevents etching of the OLED materials located over electrode segment 30.

[0067] In steps 3D and 3E, the materials, which are composed of many layers, can be removed from some portions of the horizontal surfaces using an anisotropic dry-etch processso that some portions of the surface remain. Since the dry-etching process anisotropically removes the horizontal surfaces from above, the number of the layers remaining on the substrate changes over time, thus exposing the sides (and even the top or bottoms, depending on the relative etch rates) of the remaining portion of the layers not removed.

[0068] It is very important to note that, as shown in Fig.3E, the removal of the OLED materials layer 70 not protected by photoresist 100 exposes the (substantially) vertical edges of 70 under photoresist 100 and so, is no longer fully protected by horizontal encapsulation layer 90. These exposed edges are indicated by the arrows in Figs. 3D and 3E. The newly exposed vertical edges of the OLED materials layer 70 located over bottom electrode 30 are potential areas of infiltration of air, water, vapors, or processing solutions and it is necessary to re-establish the encapsulation along the vertical edges of OLED materials layer 70. The horizontal surface of OLED materials layer 70 remains protected by horizontal encapsulation layer 90 (which lies over the top electrode 80 and under photoresist block 100).

[0069] Fig. 3F (fifth step) shows where a protective vertical encapsulation layer 110 has been deposited uniformly (no masking or patterning) over the entire surface. It should be noted that the protective encapsulation layer 110 is formed along any vertical surfaces as well as the horizontal. In this way, the newly added vertical encapsulation layer 110 can provide encapsulation along the edge (vertical side) of the organic layers 70. Although the Figure shows that the thickness of the vertical encapsulation layer is unform in both horizontal (parallel to the substrate surface) and vertical (perpendicular to the substrate) directions, there may be sagging or slumping on the vertical surfaces. It is desirable that the overall thickness of layer 110 in the vertical direction provides a suitable level of encapsulation.

[0070] Fig. 3G (sixth step) shows where the vertical encapsulation layer 110 is selectively removed from only the horizontal surfaces along with the hardened photoresist block 100 that is located over electrode segment 30. Because the removal process can be directional, the vertical portions of the vertical encapsulation layer 110 located along vertical surfaces (i.e. along the sides of the PDL 50 and the edges of the OLED materials layer 70, top electrode 80 and encapsulation 90) can remain. This step uncovers the bottom electrode segments 30’ and 30” as well as cleans the exposed surfaces of any residue created during the previous steps. The OLED pixels defined by the first set of electrode segments 30 remains protected by the horizontal encapsulation layer 90 on its upper (horizontal) surface as well as the residual vertical encapsulation layer 110 along the side (vertical) edges. At this step, fully encapsulated OLED pixels corresponding to the first set of bottom electrode segments 30 thatemit a first color of light are formed (assuming the top electrode is present) and will be unaffected by the following steps that create the other pixels necessary for a full color device.

[0071] It should be noted that since only the horizontal portions of the vertical encapsulation layer 110 are removed, all remaining portions of the vertical encapsulation layer 110 are retained, including those not connected with the pixel defined by bottom electrode segment 30. For example, Fig. 3G shows the presence of residual vertical encapsulation layer 110 along both sides of the vertical sidewalls of the PDL 50 that separates bottom electrode segments 30’ and 30”. There will also be a portion of 110 that is retained along the sides of the PDL block 50 between 30 and 30’. These will be retained through the remainder of the process.

[0072] Figs. 3H-3M illustrate the next series of steps which form an OLED pixel of a second color (different from the first) over a second set of electrode segments 30’ without affecting the first color pixels formed on electrode segments 30.

[0073] Fig. 3H (7thStep) shows where OLED materials that will emit a second color of light are uniformly deposited (no masking or patterning) over the entire surface to form OLED materials layer 120 as in Fig. 3B. OLED materials layer 120 will make direct contact with the electrode surfaces of both 30’ and 30” but not 30. This is followed, in sequence, optionally forming a top electrode 130 and then a horizontal encapsulation layer 140, both of which are deposited uniformly over the OLED materials layer 120.

[0074] Fig. 31 (8thStep) shows where a photoresist has been deposited uniformly over the surface of the substrate as in Fig. 3C, and hardened only in the area over bottom electrode segment 30’ and the remainder of the photoresist has been removed. This leaves a protective photoresist block 102 over a fully encapsulated second pixel defined by its bottom electrode 30’.

[0075] Fig. 3 J (first stage of Step 9) removes the horizontal encapsulation layer 140 and top electrode 130 (if present) over the areas not protected by the photoresist block 102 located over bottom electrode 30’ as in Fig. 3D. The organic OLED materials layer 120 is still present over 30 (corresponding to the completed pixel of the first color) and 30”.

[0076] Fig. 3K (second stage of Step 9) then removes the OLED materials layer 120 over the areas not protected by the photoresist block 102 located over bottom electrode 30’ as in Fig.

[0077] 3E. This exposes the electrode surface 30” as well as the fully encapsulated layers over 30.

[0078] The OLED pixel of the first color located over bottom electrode 30 remains unaffected because it is protected by the horizontal encapsulation layer 90 and the residual verticalportion of the vertical encapsulation layer 110. This step exposes the edges of the OLED materials layer 120 located over bottom electrode 30’.

[0079] The steps shown in Fig. 3 J and 3K may be combined.

[0080] Fig. 3L (Step 10) shows where a vertical encapsulation layer 150 has been deposited over the entire surface as in Fig. 3F. It should be noted that the vertical encapsulation layer 150 is formed along any vertical surfaces as well as the horizontal. In this way, the vertical encapsulation layer 150 can provide encapsulation along the exposed vertical edges of the organic materials layer 120.

[0081] Fig. 3M (step 11) shows where the photoresist 102 and horizontal portions of the vertical encapsulation layer 150 are removed as in Fig. 3G. The vertical encapsulation layer 150 in the vertical direction is retained and provides encapsulation to the edge of OLED materials layer 120. This forms fully encapsulated pixels corresponding to the second set of bottom electrode segments 30’ that emit a second color of light (assuming the top electrode is present). This step also exposes the surface of the third set of bottom electrode segments 30” while the first and second color pixels defined by sets of bottom electrode segments 30 and 30’ are fully encapsulated and operational.

[0082] It should be noted that since only the horizontal portions of the vertical encapsulation layer 150 are removed; all remaining portions of the vertical encapsulation layer 150 are retained, including those not connected with the pixel defined by bottom electrode segment 30’. For example, Fig. 3M shows the presence of residual vertical encapsulation layer 150 along the vertical portion of the horizontal encapsulation layer 90 that lies along the PDL between 30 and 30’ (i.e., over the pixel of the first color), as well as along the outside vertical edge of vertical encapsulation layer 110 (formed during step 6 as shown in Fig. 3G) that lies along the PDL separating 30’ and 30”. These will be retained through the remainder of the process.

[0083] Figs. 3N-3S illustrate the next series of steps which form an OLED pixel of a third color (different from the first or second) over the remaining set of electrode segments 30” without affecting the first pixel according to the first set of electrode segments 30 or the second pixel according to the second set of electrode segments 30’.

[0084] Fig. 3N (Step 12) shows where OLED materials that will emit a third color of light are uniformly deposited over the entire surface to form OLED materials layer 160 as in Figs.

[0085] 3B and 3H. OLED materials layer 160 will make direct contact with the electrode surfaces of 30”. This is followed, in sequence, with (optionally) a top electrode 170 and then horizontalencapsulation layer 180, both of which are deposited uniformly over the OLED materials layer 160.

[0086] Fig. 30 (Step 13) shows where a photoresist has been deposited uniformly over the surface of the substrate as in Figs. 3C and 31, and hardened only in the area over bottom electrode segment 30” and the remainder of the photoresist has been removed. This leaves a protective photoresist block 104 over a fully encapsulated third pixel defined by its bottom electrode 30”.

[0087] Fig. 3P (First stage of Step 14) removes the horizontal encapsulation layer 180 and top electrode 170 (if present) over the areas not protected by the photoresist 104 located over bottom electrode 30” as in Figs. 3D and 3 J. The organic OLED materials layer 160 is still present.

[0088] Fig. 3Q (Second stage of Step 14) then removes the OLED materials layer 160 over the areas not protected by the photoresist 104 located over bottom electrode 30” as in Figs.

[0089] 3E and 3K. The first and second OLED pixels remain unaffected because they are protected by the horizontal encapsulation layers 90 and 140 and the vertical encapsulation layers 110 and 150. This step exposes the edges of the OLED materials layer 160.

[0090] The steps shown in Figs. 3P and 3Q may be combined.

[0091] Fig. 3R (Step 15) shows where a vertical encapsulation layer 190 has been deposited over the entire surface as in Figs. 3F and 3L. It should be noted that the vertical encapsulation layer 190 is formed along any vertical surfaces as well as the horizontal. In this way, the vertical portion of the protective encapsulation layer 190 can provide encapsulation along the exposed edges of the OLED materials layer 160.

[0092] Fig. 3S (step 16) shows where the photoresist 104 and horizontal portions of the protective encapsulation layer 190 are removed as in Figs. 3G and 3M. The vertical portions of the vertical encapsulation layer 190 are retained and provides encapsulation to the edge of OLED materials layer 160. This forms fully encapsulated third pixels corresponding to a third set of bottom electrode segments 30” that emits a third color of light (assuming the top electrode is present).

[0093] It should be noted that since only the horizontal portions of the vertical encapsulation layer 190 are removed, all remaining portions of the vertical encapsulation layer 190 are retained, including those not connected with the pixel defined by bottom electrode segment 30”. For example, Fig. 3S shows the presence of residual vertical encapsulation layer 190 along the previously retained vertical encapsulation layer 150 over the first pixel (accordingto 30) as well as along the vertical portions of the horizontal encapsulation layer 140 over the second pixel (according to 30’). These are present in the finished display.

[0094] Some optional features of the above method are:

[0095] 1) The same materials, formulations and deposition processes can be used for the bottom electrode segments 30, 30’, 30”.

[0096] 2) The same materials, formulations and deposition processes can be used for the top electrodes 80, 130, 170.

[0097] 3) The same materials, formulations and deposition processes can be used for the horizontal encapsulation layers 90, 140, 180.

[0098] 4) The same materials, formulations and deposition processes can be used for the vertical encapsulation layers 110, 150, 190.

[0099] 5) In the first stages of step 4 (Fig. 3D), step 9 (Fig. 3J), step 14 (Fig. 3P), the same processes for the removal of the horizontal encapsulation layer and top electrode outside the protective photoresist layer can be used.

[0100] 6) In the second stages of step 4 (Fig. 3E), step 9 (Fig. 3K), step 14 (Fig. 3Q), the same processes for the removal of the organic layers outside the protective photoresist block can be used.

[0101] 7) The same processes for the removal of the protective photoresist layer and the horizontal portion of the vertical encapsulation layer as in steps 6 (Fig. 3G), 11 (Fig. 3M), 16 (Fig. 3S) can be used.

[0102] The method described above creates a pixelated OLED display that does not require the use of masks to deposit any of the OLED material(s), top electrode or encapsulation layers. Each pixel is independently operated and requires (as is defined by) at least one segmented electrode. The active (light-emitting) areas of each pixel may be the same or different sizes as desired. A display has pixels and / or subpixels arranged in a pattern as desired. Each pixel or subpixel emits light at some level and period of time (frame) to create an emission pattern that represents a pixelated image.

[0103] While the above method has been described in terms of making pixelated OLED displays using vapor deposition of the OLED materials, it can equally be used for OLED devices where the OLED materials are deposited using other methods such as wet coating, slot-die, ink-jet or similar methods. Such methods are particularly suitable when the OLED materials are either polymeric, dissolved in a solvent, or as a dispersion in a liquid. Quantum Dots (QD) may be used as the OLED material. Vapor deposition of the OLED materials layer without masking is preferred.The method is also not limited to 3-color OLED displays; the pixelated OLED display may be monochromatic (particularly, where all pixels emit G light), bicolor (i.e., all pixels may emit either B or orange light), or 4-color (i.e., R, G, B and W light) or more. A monochromatic display will only need 1 set of electrode segments; a bicolor display will need 2 sets of electrode segments while a 4-color display will need 4 sets of electrode segments.

[0104] Moreover, the general methodology can be applied to making displays that emit light using technologies other than OLED. The basic requirement is that the display has multiple layers that are formed one over another and require full encapsulation. OLED or QD displays are preferred.

[0105] An individual pixel can emit a single color of light (i.e., R, G or B) or may be fullcolor; that is, each pixel is composed of sub-pixels that each emit a single color of light. The single color of light may be generated within the display by a single layer with one or more emitters of the same color or multiple layers, each with the same or different emitters whose primary emission fall within the same color. A single pixel can also provide a combination of two colors (i.e., R+G, R+B, G+B) within a single OLED unit by having: one layer with a single emitter that emits two colors of light, one layer with two different emitters, or combinations of multiple separate layers, each emitting a single, but different, color. A single pixel may also provide white light (a combination of R, G and B) by having one layer that emits all three colors of light or combinations of multiple separate layers, each emitting a single (but different) color, the sum of which is white. The light-emitting layers within a single pixel may be either directly above or below each other or separated from each other by interlayers.

[0106] The pixels may also be according to a stacked OLED structure containing at least two or more individual OLED light-emitting units which are always separated from each other by a non-light emitting charge generation layer (CGL). A light emitting unit is considered to be a grouping of a light-emitting layer(s) along with any auxiliary layers (i.e. a hole-transport layer, an electron-transport layer, etc.). If there is no CGL present, it has a “one stack” structure, even though it may have more than one light-emitting layer that makes up the single OLED unit. A “two-stack” OLED structure would have a CGL that separates two lightemitting units. In other words, to be considered an OLED light-emitting unit, it must be separated from another light-generating unit by a CGL; however, it is not necessary for a light-generating unit to have an adjacent CGL on both sides. The OLED light-generating units on the top and bottom of the stack will generally have only one adjacent CGL. There is typically no need to use a CGL between a light-emitting unit and one of the top or bottomelectrodes, although a CGL could be used if desired. Within the stacked OLED structure, the individual OLED light-emitting units can be placed in any order between the top and bottom electrodes.

[0107] The OLED structure may be arranged to be a microcavity. This requires that one electrode be reflective and the other to be semi-transparent. The thicknesses of the internal layers are adjusted according to the desired color of emitted light.

[0108] The substrate can be rigid and made of glass, silicon, metal or rigid plastic or polymer. Alternatively, the substrate is flexible and can be made of flexible glass, metal or polymeric materials. Generally speaking, it will be flat with a uniform thickness. For bottom emitting displays, the substrate should be transparent. For top emitting displays, the substrate may be opaque or transparent (allowing for two-sided emission) as desired. Since the substrate will be part of the overall encapsulation for the OLED, it should be sufficiently impervious to air and water so that the OLED will have the desired lifetime. The OLED substrate may have various types of subbing layers which may be patterned or un-patterned and can be either on the top or bottom surfaces.

[0109] The display may have either a passive-matrix or active-matrix design. The activematrix design is preferred. In such designs, the control circuitry for each pixel is contained between the bottom electrode of the pixel and the substrate. The combination of the substrate along with the layer(s) that contains the control circuitry is referred to as a backplane. If the substrate of the backplane is silicon, the display will be top-emitting. If the substate of the backplane is glass or polymeric, the display may be top-emitting or bottom-emitting as desired. However, the control circuitry is often light sensitive. If the display is bottomemitting, then the control circuitry must be shielded from the light, either through the use of light-blocking or reflective layers or by locating the control circuity off to the side of the emission path. A silicon backplane with embedded control circuitry as the substrate is desirable.

[0110] The initial step of the process is preparing a display substrate with patterned bottom electrode segments separated by a PDL (Pixel Definition Layer). Thus, each pixel (or subpixel) will have its own individual bottom electrode segment that is electrically insulated from its neighbors. Each electrode segment is electrically connected to the control circuitry in the backplane, which supplies the appropriate amount of power for the appropriate amount of time to order to generate the desired image.

[0111] The bottom electrode segment is made of any electrically conductive material.

[0112] Preferably, it is made of a conductive metal salt (i.e. ITO or AZO) or a metal (i.e. Al or Ag) ormetal alloy (Mg / Al or Mg / Ag). The bottom electrode can be opaque for a top-emitting display, and transparent for a bottom-emitting display. For top-emitting displays including those that include a microcavity effect, the bottom electrode segments may be bilayer where the bottommost layer is a reflective metal such as Ag and the upper layer is a metal salt such as ITO.

[0113] The bottom electrode segments can be patterned directly over the substrate or backplane using standard sputtering (with masking) or photolithography (wet or dry) methods. There may be one or more layers (for example, a light-scattering layer) between the electrode segments and the substrate orbackplane.

[0114] There is an electrically insulating pixel definition layer (PDL) in the gaps separating the bottom electrode segments so there is no electrical contact between them. Thus, each individual pixel (or subpixel) will be defined by having an individual bottom electrode segment. There is no emission from the area with the PDL, resulting in a non-emitting gap between pixel emission areas.

[0115] Suitable PDL materials may be polymeric or inorganic. Some examples of a suitable polymeric PDL include acrylic and polyimide polymers. Some examples of a suitable inorganic PDL include AI2O3, SiCh, SiN and SiON. Desirably, the PDL is a hardened photoresist that is patterned via photolithography. It is important that the PDL be relatively unaffected by the processes that are used for material removal in some steps. The PDL must be robust enough so that it is not significantly affected by any of the etching processes that removes overlying layers. For example, O2 plasma may be used to remove the OLED materials layer over the PDL in steps 6 (Fig. 3G), 11 (Fig. 3M) and 16 (Fig. 3S) but the PDL should remain. Inorganic PDL materials, such as silicon nitride or silicon dioxide, generally are not etched in low-power O2 plasma processes. For an organic PDL such as a hardened photoresist, it is possible to enhance its resistance to O2 by a substantial hardbake. In this case, some of the PDL may be removed during this step, however it will be a negligible amount. (<10 nm). It is also possible to passivate the PDL with suitable treatments or coatings before processing.

[0116] The PDL may be patterned using standard sputtering (with masking) or photolithography (wet or dry) methods over the previously formed bottom electrode segments. Alternatively, it may be formed directly on the substrate or backplane with gaps so that the segmented bottom segments can be subsequentially formed so they lie directly on the substrate or backplane within those gaps.The PDL may be thicker than the bottom electrode segments so that it extends above the surface of the electrode (as illustrated in Fig. 3 A) or have the same thickness as the bottom electrode segments. The PDL may also overlap or extend partially over the upper surface of the bottom electrode segment in some embodiments.

[0117] The shape of the side walls of the PDL structure that rises above the electrode segments may be important in some embodiments. In Fig. 3 A, the PDL is shown as having vertical side walls with a flat top. However, this can lead to coating defects when overcoated with the OLED materials and horizontal encapsulation layer since it is difficult to uniformly vacuum coat vertical surfaces. Thus, the PDL may have sloping side walls (i.e., a trapezoid shaped cross-section) and / or a rounded top.

[0118] It is desirable that the width of the PDL should be as small as practical so the emitting area is large, reducing the required current density to achieve a desired brightness. Narrower widths between exposed electrode segments will allow the device to have a longer lifetime. It is desirable to have an aperture ratio (area of emission divided by total area of the display) in the range of 60-80%, and more preferably in the range of 80-95%. Ideally, the PDL layer should be no more than 5 microns thick (above the substrate) and desirably in the range of 0.2-3.0 microns. Desirably, the width of the non-emitting PDL between the emissive area between two pixels is 20% or less, or more desirably, 10% or less of the total width of both pixels plus the PDL.

[0119] The second step of the process (see Fig. 3B) is where the substrate with the patterned bottom electrode segments and PDL is overcoated uniformly via vapor deposition (no masks or patterning) with a layer or layers of suitable OLED materials. Such materials may include all the necessary OLED layers required to create a pixel that emits a first color of light.

[0120] OLEDs (Organic Light-Emitting Diodes) are composed of many thin layers of materials deposited over a substrate, one over another. At a minimum, an OLED will have a bottom electrode, at least one light-emitting layer, and a top electrode. There may be other layers present between the two electrodes such as hole-injection layers, hole-transport layers, hole-blocking layers, electron-blocking layers, electron-injection layers, spacing or intermediate layers, light-modifying layers, light-scattering layers, light-conversion layers and the like as necessary for the OLED layers to efficiently produce light. A light-emitting layer will typically have one or more light-emitting materials (which may be fluorescent or phosphorescent or both) in one or more non-light emitting host materials. Such OLED materials are well-known in the art and may be selected as desired. It should be noted that the method does not allow for common organic layers across multiple pixels; each pixel willhave separate organic layers even though some layers (i.e. the top electrode) may be common across some or all pixels. OLED materials layer refers to all layers between the bottom and top electrodes.

[0121] Included at this stage are subsequent steps include where the OLED materials layer is further overcoated uniformly via vapor deposition (no masks or patterning) with a top electrode (optional step) followed by a horizontal encapsulation layer. In some embodiments, the top electrode may be patterned using masks. There may be additional layers between the top electrode (if present) and the horizontal encapsulation layer. There may be additional layers over the horizontal encapsulation layer as well. The top electrode may be a metal oxide such as ITO or a metal such as Al or Ag, which may be opaque, reflective or transparent, and may be composed of multiple layers. The horizontal encapsulation layer may be inorganic (i.e. a mixture of metal oxides such as AI2O3 and ZrO?) and may be composed of multiple layers. Alternatively, the horizontal encapsulation layer may be composed of alternating organic and inorganic layers. The horizontal encapsulation layer may be transparent or opaque. The horizontal encapsulation layer provides protection against air and water penetration for the upper (horizontal) surface of the OLED materials. After completion of this step, the OLED pixel of the first color over the bottom electrode segment 30 is fully encapsulated and is operational (light-emitting when supplied with power, assuming the top electrode is present) in the areas over the bottom electrode segments but not over the PDL.

[0122] Since the OLED materials layer, the top electrode and the horizontal encapsulation layer can all be deposited uniformly over the substrate surface during the second step, they will be continuous and unbroken over all of the bottom electrodes as well as the PDL structures. In embodiments where the PDL extends above the surface of the bottom electrode segments, these layers will only be horizontal over the bottom electrode surface and then rise up and over the PDL surface. In particular, it should be understood that the horizontal encapsulation layer will have sections along either side of the PDL that are not horizontal but, in fact, could be near-vertical or vertical. However, these non-horizontal sections will be small compared to the overall size of the pixel (10% or less). Although Fig. 3B shows that the thicknesses of the deposited OLED material layer, top electrode and horizontal encapsulation layer are the same in both horizontal and vertical directions over the raised PD structure, in practice, this may not occur and sagging or thinning may occur along the side walls of the PDL.

[0123] Although the bottom electrode is shown as being segmented in Fig. 3, the bottom electrode may also be continuous so that the PDL lies on top of the electrode. As an example,a uniform layer of transparent metal oxide such as ITO or a metal such as Al or Ag is uniformly deposited over a suitable substrate (i.e., glass) surface. Then, the individual PDL segments are patterned over the bottom electrode using standard sputtering techniques (with masking) or via photolithography using dry etching or wet processes to remove the photoresist in undesired locations). In such embodiments, the top electrode will be segmented in order that the pixels can be independently controlled.

[0124] However, since the second step of the process forms an OLED that emits a first color uniformly over the substrate including areas where it is unwanted (i.e., over electrode segments 30’ and 30”), it is necessary to remove the OLED from those areas. In order to accomplish this, it is necessary to protect the OLED that was formed in the desired area (i.e., over electrode segment 30) from being damaged or removed during removal of the OLED in the undesired areas.

[0125] A protective block (layer) is necessary to protect the surface of the completed OLED pixels in the desired area from subsequent operations. In some embodiments, the protective block can be formed by uniform deposition of photoresist over the surface of the entire substrate and hardened only in the area over one of the bottom electrode segments (30) and processed to create a region or block of residual protective block over the electrode segments 30 (with the remainder of the block removed). The protective block can be made of any material that can be formed and removed without damaging the underlying encapsulated OLED. The protective block may extend past the boundaries of the bottom electrode and partially overlap the PDL. The thickness of the protective block can be as desired and necessary to provide adequate protection during the next steps.

[0126] Desirably, the protective block is formed by a hardened photoresist formed using photolithography (as shown in Fig. 3). Such photolithographic processes are well-known. Both positive and negative photoresists can be used to form the residual block of photoresist. Because at this step, the OLED materials layer is fully encapsulated by horizontal encapsulation layer, the OLED is unaffected during the photolithographic process. This leaves a block of protective photoresist layer over a pixel or group of pixels (of a first color) as defined by its bottom electrode 30.

[0127] Dry etch processes are used to remove the OLED (of the first color) from the unwanted areas (over electrode segments 30’ and 30”) without affecting the OLED pixel of the first color over electrode segment 30, which is protected by the protective block. Dry etching refers to the removal of material by exposing the material to a bombardment of ions (usually a plasma of reactive gases sometimes with addition of nitrogen, argon,helium and other gases) that dislodge portions of the material from the exposed surface. Such dry etching process are well-known and the equipment and hardware for performing such processes are commercially available. Since the dry etching process typically etches directionally or anisotropically, the removal process can be confined to certain locations and not the entire surface. In particular, the anisotropic removal of material should be substantially in the vertical direction from above so that removal of the bulk materials in the horizontal direction will leave a vertical edge in the unremoved material. In this case, the anisotropic removal of the horizontal layers not protected by the protective block creates an exposed vertical edge of the protected OLED layers under the block. This exposed vertical edge should be located over the PDL layer.

[0128] The dry etching process to remove the OLED materials layer (along with top electrode (if present) and horizontal encapsulating layer (the fourth step) can be performed entirely in one step or more preferably, is divided into two separate stages. Each stage can be further divided into two or more phases. It should be noted that the removal process should not affect the OLED over bottom electrode segment 30 which is protected by photoresist block, and leave exposed the bottom electrode segments 30’ and 30” as well as the PDL layers 50 that separate them.

[0129] As the first stage of a two-part removal process, only the horizontal encapsulation layer and the top electrode (if present) are removed via dry etching in the locations not protected by the photoresist block. In this embodiment, the OLED materials layer is not removed during this step. This may be because a protective ash layer is formed at the upper surface of the OLED layers which prevents or slows the dry etching.

[0130] The removal of the horizontal encapsulation layer and top electrode in the first stage of a two-part process of step 4 (Fig. 3D) as well as in later step 9 (Fig. 3 J) and step 15 (Fig.

[0131] 3P) can be any suitable dry-etch method. Desirably, the dry-etch process to remove only materials on a horizontal surface should use lower pressures since the lower the pressure of the dry-etch process, the more anisotropic the etch becomes. Suitable low pressures should be no more than 50 mTorr desirably no more than 30 mTorr, and preferably in the range of 10-15 mTorr.

[0132] In one embodiment, both the horizontal encapsulation layer and top electrode are removed in a single phase in the first stage of step 4. This can be accomplished using CCI4+BCI3 (with or without argon). The selected process may be performed over the entire surface (assuming the protective photoresist layer is not significantly affected) or anisotropically where the etching is limited to certain locations (in this case, in areas notprotected by the photoresist). For example, suitable conditions for a CCI4+BCI3 etch using a RIE-ICP process are in the range of 1 seem (standard cubic centimeters per minute) to 100 seem at 10-300 mTorr for 30-900 sec. A specific example of a suitable process condition is 15 seem CCI4, 30 seem BCI3, 20 seem Ar, 250W at 15 mTorr for 90 seconds.

[0133] In another embodiment, the first stage of step 4 is divided into two separate phases. In a first phase, the horizontal encapsulation layer is substantially, but not entirely removed using a fluorine based dry etch process. This first phase can be accomplished using CF4+CHF3+O2 (with or without argon). For example, suitable conditions for a CF4+CHF3+O2 etch using a RIE-ICP process are in the range of 1 seem to 100 seem at 15-300 mTorr for 30-900 sec. A specific example of a suitable process condition is 60 seem CF4, 60 seem CHF3, 100 seem Ar and 5 seem O2 at 100 mTorr for 600 sec. Note that these specific conditions for removing the encapsulation layer before removing the top electrode and OLED materials layer does not require low pressure. In this example, a higher pressure is desirable to ensure that the encapsulation film is removed at a reasonable etch rate. A pressure higher than lOOmTorr slows the etch rate considerably, while a pressure lower than lOOmTorr risks damaging surrounding films.

[0134] In this embodiment, the second phase of the first stage of step 4 removes the remaining portion of the horizontal encapsulation layer and the entire top electrode (if present) using a chlorine based dry etch process. This second phase can be accomplished using CCI4+BCI3. For example, suitable conditions for a CCI4+BCI3 etch using a RIE-ICP process are in the range of 1 seem (standard cubic centimeters per minute) to 100 seem at 10-300 mTorr for 30-900 sec. A specific example of a suitable process condition for this second phase is 15 seem CCI4, 30 seem BCI3, and 20 seem Ar at 15 mTorr for 90 sec.

[0135] As the second stage of a two-part process, the OLED material layer is removed in the areas not protected by the photoresist block using a second dry etch. It may be that the surface of the photoresist layer is protected partially by formation of ash or decomposition products formed by this step or during the first step.

[0136] The removal of the organic OLED material layer in the second stage of Step 4 (Fig.

[0137] 3E) as well as in later step 9 (Fig. 3K) and step 14 (Fig. 3Q) can be any suitable dry-etch method but is desirably by SFe (with or without O2, CF4, or argon in any combination). The selected process may be performed over the entire surface (assuming the protective photoresist layer is not significantly affected) or anisotropically where the etching is limited to certain locations (in this case, in areas not protected by the photoresist). For example, suitable conditions for a SFe etch using a RIE process (Trion Phantom®) are in the range of: 5seem to 100 seem at 10-300 mTorr for 30-900 sec. A specific example of a suitable process condition is 50 seem SFe, 10 seem O2, 10 seem CF4200W at 30 mTorr for 180 seconds.

[0138] Since after the selective removal of the OLED materials layer, top electrode (if present) and horizontal encapsulation layer in undesired areas, the edges of the remaining OLED materials layer under the protective block become exposed and are no longer encapsulated. This is indicated by the arrows in Figs. 3E and 3D. Wet etching methods cannot be used to remove the undesired OLED materials layer since the edges of the remaining OLED material will be exposed during the process. In order to have a fully encapsulated OLED pixel, it is necessary to re-establish the encapsulation along the exposed vertical edges of the OLED materials layer.

[0139] The next step (i.e., as shown in Fig. 3F) re-establishes the encapsulation of the OLED over bottom electrode segment 30 by uniformly depositing (no masking or patterning) a vertical encapsulation layer over the entire surface of the substrate, including all horizontal and vertical surfaces. This effectively covers the previously exposed edges of the OLED materials layer over the PDL that separates the bottom electrode segments 30 and 30’.

[0140] Because the vertical encapsulation layer provides encapsulation to the (vertical) edges of the OLED materials layer, it should be composed of a material (or materials) that will provide sufficient protection against air and water penetration to the exposed edges. Although it provides the same function as the horizontal encapsulation layer, the vertical encapsulation layer is formed during a different step as well as having a different final orientation. While both encapsulation layers may be formed of the same materials, this is not necessary and, because of the orientation differences, it may be necessary to use different materials. It should be understood that the vertical encapsulation layer as initially formed will have sections that are horizontal as well as having sections along either side of the PDL that will be nonhorizontal; in fact, will be near-vertical or vertical. The horizontal portions of the vertical encapsulation layer will be subsequentially removed so that only the near-vertical or vertical portions remain. These non-horizontal sections will be small compared to the overall size of the pixel (10% or less).

[0141] It is necessary to deposit the vertical encapsulation layer at a sufficient thickness on an approximately vertical surface whereas the horizontal encapsulation layer can be deposited on a flat horizontal surface (except where the PDL is higher than the electrode segments). Suitable methods include LPCVD (low-pressure chemical vapor deposition), thermal evaporation, E-Beam evaporation, flash evaporation, and / or sputtering. Desirably, the vertical encapsulation layer can be deposited by a RIE-ICP process or plasma-enhancedchemical vapor deposition (PECVD) process. PECVD is a chemical vapor deposition process used to deposit thin films from a gas state (vapor) to a solid state on a substrate. Chemical reactions are involved in the process, which occur after creation of a plasma of the reacting gases. The plasma is generally created by radio frequency (RF), alternating current (AC) frequency or direct current (DC) discharge between two electrodes, the space between which is filled with the reacting gases. Both of these processes have the advantage that all surfaces can be uniformly coated no matter the orientation. Moreover, it may not be necessary to expose the substrate to the atmosphere after step 4, as well as steps 9 and 14, where the OLED edges are not encapsulated since either process can be used in the same high vacuum equipment.

[0142] The vertical encapsulation layer in step 5 (Fig. 3F) as well as in step 10 (Fig. 3L) and step 15 (Fig. 3R) can be any suitable material that can deposited uniformly so that both the horizontal and vertical surfaces of the substrate are coated without using masks. A RIE-ICP or PECVD process is preferred. Desirably, the vertical encapsulation layer is derived from a fluorocarbon precursor. Any fluorocarbon precursor with less than 8, preferably 4 or less, carbon atoms that can be uniformly deposited can be used. The fluorocarbon precursor can be linear, cyclic, saturated or unsaturated. Preferred precursor examples include CF4, C2F4, C2F6, C3F6, C3F8, C4F8 or C4F10. For example, suitable conditions for depositing a fluorocarbon layer using a CF4 plasma are in the range of 1 seem to 100 seem at 15-300 mTorr for 30-900 sec. A specific example for the fluorocarbon layer formation is via a Trion Phantom® RIE-ICP process where the conditions are 30 seem CF4 at 100W, 120 mTorr for 200 seconds.

[0143] After the uniform deposition of the vertical encapsulation over the entire substrate surface, it must be removed from all horizontal surfaces. Moreover, the residual photoresist block over the OLED as defined by the bottom electrodes needs to be removed. This is as shown in step 6. The simultaneous removal of the protective block along with the vertical encapsulation layer on any horizontal surfaces (but not along the vertical surfaces) in Steps 6 (Fig. 3G), 11 (Fig. 3M) and 16 (Fig. 3S) can be any suitable dry-etch method but is desirably by O2 plasma. The removal process may be performed over the entire surface or anisotropically where the etching is limited to certain locations. In these steps, an anisotropic ICP (Inductively Coupled Plasma) process is highly preferred since it only removes the horizontal portions of the vertical encapsulation layer. In particular, ICP allows low pressure RIE (10-50 mTorr) which results in very anisotropic etch profiles. The protective (photoresist) block is removed at the same time. However, all the portions of the vertical encapsulation layer that are orientated in the vertical direction are retained as well as theportion that provides encapsulation to the edge of the OLED defined by bottom electrode 30.

[0144] This is illustrated in Fig. 3G where the vertical portions of the vertical encapsulation layer 110 along either side of the PDL 50 between bottom electrode segments 30’ and 30” are still present after all horizontal portions are removed.

[0145] For example, suitable conditions for removing the protective (photoresist) block and the horizontal portions of vertical encapsulation layer using a O2 plasma are in the range of: 5 seem to 50 seem. A specific example for the O2 plasma process is via a Plasma- Therm® ICP process where the conditions are 10 seem O2 at 50W, 15 mTorr for 60 seconds.

[0146] Similar materials and processes as used to create the OLED pixel of the first color (as discussed above) also be used for the next series of steps which form an OLED pixel of a second color (Figs. 3H-3M) over electrode segment 30’ as well as those subsequent steps which form an OLED pixel of a third color (Figs. 3N-3S) over electrode segment 30”.

[0147] The display prepared by the method shown in Figs 3A-3S have top electrode segments that overlap the bottom electrode segments and partially along top of the PD. The described method lends itself to having a stripe pattern of pixels where each column of pixels emits the same color. While the top electrode of each pixel can be independently controlled in a stripe pattern, it would be desirable to have a common top electrode that extends over all the pixels in the stripe.

[0148] Figs 4A1-4D1 (cross-sectional) and 4A2-4D2 (overhead or plan) views of a row of three pixels within a display prepared in a similar method shown in 3A-3S. The pixels represent the first pixel in a columnar stripe pattern that all emit the same color. In this embodiment, the PDL 50 is expanded so that pixels are further apart. In this case, the horizontal and vertical encapsulation layers of each pixel, which in Figures 3A-3S are shown as butting up to each other over the PDL, stop over the top of the PDL 50 and are spaced apart so that a section of the PDL remains exposed.

[0149] Fig. 4A1 is a cross-section that shows the substrate 10 with a row of electrode segments (30, 30’ and 30”) separated by the PDL 50. It is similar to the view shown in Fig.

[0150] 3 A. The first electrode segment on the left will become a pixel of a first color. The middle electrode segment will become a pixel of a second color. The remaining electrode segment on the right will become a pixel of a third color. As shown, the PDL layer 50 is thicker than the electrode segments and so, has side walls that border the edges of the electrode segment.

[0151] Fig. 4A2 is an overhead view of the electrode segments / PDL of Fig. 4A2. It should be noted that not all of the electrode segments are the same size. Because there are portions of the vertical encapsulation layer that remain throughout the process over the sides of theemitting areas of the pixel, they may (if sufficiently thick) decrease the active emitting area of the OLED pixel. Increasing the size of the electrode segments where the portions of the vertical encapsulation layer remain will allow for the same pixel size in the completed device. For example, referring to Fig. 3S, vertical encapsulation layers (110 and 150) deposited for electrode segments 30 and 30’ may encroach on the area of electrode segment 30”, reducing its effective area. In contrast, vertical encapsulation layers deposited over electrode segments 30’ and 30” may cover a portion of electrode segment 30, and if partially opaque may reduce the area of light emitted. However, if the vertical encapsulation layer(s) are thin, this may not be necessary.

[0152] Fig. 4B1 is a cross-section showing the OLED device after Step 7 (Fig. 3G) of the process is completed. At this stage, all of the pixels of the first color (according to electrode segments 30) are fully formed and encapsulated. Note that in the left column, top electrode layer 80 has been extended towards the boundary of the substrate 10 and outside the areas bounded by the encapsulation 90 which is bordered by vertical encapsulation layer 110. The extension of top electrode layer 80 can be patterned to be longer or the extended potion can be formed. The extended electrode may be patterned using an anisotropic dry-etch process or by a sputtering or vapor deposition process using masks. This will eventually create an electrode contact pad for external electrical connection to the top electrode 80. 202 is a step change in height in the horizontal encapsulation layer 90 between the top of the PDL 50 and the horizontal encapsulation layer 90. Fig. 4B1 also shows that the vertical encapsulation layer 110 remains on the vertical walls of the PDL 50 that border the middle column of electrode segments 30’ and the right column of electrode segments 30”. Because of the residual presence of the vertical encapsulation layer 110 over the electrode segments 30’ and 30”, the effective emitting areas will be reduced.

[0153] Fig. 4C1 is a cross-section showing the OLED device after Step 11 (Fig. 3M) of the process is completed. At this stage, all of the pixels of the second color (according to electrode segments 30’) are fully formed and encapsulated. Note that in the middle column, top electrode layer 130 has been extended outside the areas bounded by the encapsulation 140 in order to create another contact pad. The vertical encapsulation layer 110 along the vertical walls of the PDL (as per Fig. 4A2) surrounding the middle column is no longer visible (being overcoated by layers 120 / 130 / 140); however, the horizontal encapsulation layer 140 is now bordered by vertical encapsulation layer 150. As shown in the overhead view of Fig. 4C2, it should be noted that the vertical walls of the PDL 50 bordering the first column, previously coated with vertical encapsulation layer 110 (Fig. 4B) are now bordered with a residualsecond layer of vertical encapsulation layer 150. 202 shows the step change in height in 140.

[0154] In the right column, a layer of vertical encapsulation layer 150 overcoats the previously formed layer of vertical encapsulation layer 110 along the inside vertical edges of the bordering PDL. Likewise, residual vertical encapsulation layer 150 also remains along the sidewall of PDL bordering electrode segment 30”. This will decrease the effective emission area in the corresponding pixel when fully formed.

[0155] Fig. 4D1 is a cross-section showing the OLED device after Step 16 (Fig. 3S) of the process is completed. At this stage, all of the pixels of the third color (according to electrode segments 30”) are fully formed and encapsulated. Note that in the right column, top electrode layer 170 has been extended outside the areas bounded by the encapsulation 180. In the right column, previously visible (Fig. 4C2) vertical encapsulation layers 110 and 150 are no longer visible (being overcoated by layers 160 / 170 / 180). In Fig. 4D2, the horizontal encapsulation layer 180 (with 202 shows the step change in height in 180) is now bordered by residual vertical encapsulation layer 190. It should be noted that the vertical walls of the PDL bordering the first column, previously coated with layers of vertical encapsulation layers 110 and 150 (Fig. 4C2) are now bordered with a third layer of vertical encapsulation layer 190.

[0156] The vertical encapsulation layer 150 along the vertical walls of the PDL surrounding the middle column is bordered with another layer of vertical encapsulation layer 190. Because the starting sizes (areas) of the bottom electrodes in each column are different in this embodiment in order to account of the presence of residual portions of the vertical encapsulation layers over the edges of each pixel, the emitting areas of the pixels in each column can be made the same.

[0157] Since the PDL itself may not provide sufficient protection against oxygen and water, a secondary encapsulation and / or planarization layer over the surface of the display if any section of the PDL is not covered by the horizontal or vertical encapsulation layers. This also may be necessary for the outside boundary (near the edges of the substrate) formed by the display pixels.

[0158] It would be desirable to have other pixel arrangements other than a stripe pattern. This requires that the top electrode to be common across all color of pixels within the active emissive area.

[0159] Fig. 5 shows an embodiment where the external contact pads are electrically connected together outside of the border of the pixels (near the edge of the substrate) after completion of the device according to the described method. Fig. 5 shows the same device as shown in Fig. 4D2 where an electrically conductive layer 200 (preferably the samecomposition as the top electrode) is then formed across and in electrical contact with the contact pads of 80, 130 and 170 to form a “mesh” top electrode which is now common across all pixels. A second similarly electrically conductive layer may be located near the opposite edge of the device as well. It is also possible to deposit a uniform conductive layer over the top of the completed encapsulated device and make contact to the top electrodes of the pixel through the encapsulation using vias.

[0160] The method as described in Figs 3A-3S and Figs. 4A-4D is most suitable for a pixel arrangement where all pixels that emit the same color are arranged as a linear stripe. In this way, the top electrodes of all pixels of the same color (which all lie along the same column) can be made common and electrical connections to the common top electrode can be made at the end of the substrate and outside the emission area of the substrate. This is illustrated in Fig. 4D which shows the separate external contact pads for top electrodes 80, 130 and 170.

[0161] However, it would be desirable to have other pixel arrangements other than a stripe pattern. This requires that the top electrode to be common across all color of pixels within the active emissive area.

[0162] Fig. 5 shows an embodiment where the external contact pads are electrically connected together outside of the encapsulation after completion of the device according to the described method. Fig. 5 shows the same device as shown in Fig. 4D where an electrically conductive layer 200 (preferably the same composition as the top electrode) is then formed across and in electrical contact with the contact pads of 80, 130 and 170 to form a “mesh” top electrode which is now common across all pixels. It is also possible to deposit a uniform conductive layer over the top of the completed encapsulated device and make contact to the top electrodes of the pixel through the encapsulation using vias.

[0163] In other embodiments, the process can be modified so that only part of each column is formed in one series of steps so that the encapsulation only covers a portion of each column. This allows for additional conductive layers to be formed (after the process is complete) between the encapsulated sections and connected to the top electrodes in other encapsulated sections in a different column. This allows for an increased density of the “mesh” by allowing interconnections within the active emission area as opposed to just the ends as shown in Fig.

[0164] 5.

[0165] An alternative method for making an OLED display with a common top electrode is illustrated in Fig. 6. It is similar to the method shown in Fig. 3 except that the top electrode layers 80, 130 and 170 are not included in Steps 2, 7 and 12 so that the horizontalencapsulation layers 90, 140 and 180 are located over the OLED materials layer 70, 120 and 160

[0166] In this embodiment, Fig. 6A shows that after step 6, the top electrode 80 is not present over bottom electrode segments 30 (compare to Fig. 6G). Fig. 6B shows that after step 11, the top electrode 130 is not present over bottom electrode segments 30’ (compare to Fig. 3M). Fig. 6C shows that after step 16, the top electrode 170 is not present over bottom electrode segments 30” (compare to Fig. 3S).

[0167] Fig. 6D shows the next step where in Fig. 6C, sections of the horizontal encapsulation layers 90, 140 and 180 over the bottom electrode segments 30, 30’ and 30” are removed, exposing the OLED material layers 70, 120 and 160. Preferably, this removal of the OLED materials can be accomplished using a RIE-ICP dry etch process using CF4+CHF3+O2 as previously described. Although Fig. 6D illustrates an anisotropic process where sections of the horizontal encapsulation layer are removed only over or near the bottom electrode segments, it is also possible that the horizontal encapsulation layer is uniformly removed over the entire surface, including over the PDL between the electrode segments.

[0168] Fig. 6E shows where a common top electrode 205 is deposited over the entire surface as shown in Fig. 6D. This forms complete OLED pixels of a first color over bottom electrode segments 30, of a second color over bottom electrode segments 30’ and of a third color over bottom electrode segments 30”. However, these pixels are not encapsulated on their horizontal surface. Fig. 6F shows the formation of a common encapsulation layer 210 over the entire surface. This forms a fully encapsulated OLED display.

[0169] The photolithography materials and processes used in this method of making pixelated displays are all well-known. They may be positive or negative-working. In the various steps that require photolithography to pattern protecting photoresist layers, the same or different materials can be used. It is preferred not to use any wet removal methods in the presence of unencapsulated OLED materials; the described method avoids these types of processes.

[0170] Each pixel of OLED light-emitting unit should be fully encapsulated. By “fully encapsulated”, it is meant that all surfaces of the sensitive OLED materials are protected by materials that are impervious to water and oxygen. The top horizontal surface is protected by the horizontal encapsulation layer. The bottom horizontal surface is protected by the substrate. The outside edges of the emitting area of the device (i.e., edges not bordered by another pixel) can be protected by extending the horizontal encapsulation layer over that edge or providing other kinds of encapsulation. The edge created by the removal of the undesiredOLED materials, which is located over the PDL, is protected by the vertical encapsulation layer. Desirably, the encapsulation material has a water vapor transmission rate (WVTR) of 10'6g / m2 / day or less. Desirably, the encapsulation is also a barrier to oxygen and has an oxygen transmission rate of 10'4g / m2 / day or less.

[0171] The OLED pixels desirably have the bottom electrode as an anode and the top electrode is a cathode. The OLED pixels are desirably top-emitting.

[0172] Experimental Example

[0173] An example according to the described method was prepared as follows. It should be noted that this example is not a pixelated display since the bottom electrode is common so that pixels are not independently controlled. All pixels, no matter the emitted color, emit the same according to the supplied power.

[0174] Step 1 : A glass substrate overcoated with a uniform layer of ITO as a bottom electrode had a pattern of 1.0 pm thick photoresist (Merck AZ® MiR™ 701 Series Positive Tone Photoresist) as a PDL formed using standard photolithography processes. This creates a PDL pattern, similar to that of Fig. 4A-4D, where the underlying exposed ITO electrode surface forms columns and rows between the PDL. The individual exposed electrode surfaces were 50 pm square. It should be noted that, even though the bottom electrode is continuous in this experiment, the pixels will still be divided into segments due to the pattern of electrically insulating pixel definition layer.

[0175] Step 2: A two-stack tandem green OLED structure including all necessary organic layers, a 15 nm thick aluminum top electrode and a 100 nm thick horizontal encapsulation layer of a nanolaminate (mixture of AI2O3 and ZrO?) was then uniformly (no masking or patterning) formed over the top surface of the above substrate via a vacuum deposition process. This creates a surface where the encapsulated OLED overlies both the PDL blocks and the ITO electrode surface.

[0176] Step 3 : A pattern of 0.2 pm thick photoresist blocks (KemLab™ KL 5302 High Resolution Positive Thin Photoresist) were formed only over every third column where OLED is directly over the ITO surface, that is, over columns 1, 4, 7, etc. The block also partially overlaps the PDL on either side.

[0177] Step 4: In a first stage of the removal of the OLED in areas not protected by the photoresist blocks, the horizontal encapsulation layer and top electrode are removed in two phases. The first phase is a fluorine etch using a RIE-ICP process (Trion Phantom;

[0178] ICP@500W, RIE@150W) where there is a 600 sec exposure to 60 seem CF4, 60 seem CHF3, 100 seem Ar and 5 seem O2 at 100 mTorr. This step etches the horizontal encapsulation layerto about 10 nm but doesn’t remove it completely. The second phase is where the removal conditions are changed to a chlorine etch (Plasmatherm; ICP@600W; RIE@250W) of 90 sec exposure to 15 seem CCU, 30 seem BCh, and 20 ccm Ar at 15 mTorr. This completely removes the horizontal encapsulation layer and top electrode, leaving the OLED materials layer as well as the photoresist blocks.

[0179] In a second stage of Step 4, the remaining OLED materials layer is removed using a sulfur hexafluoride etch using a RIE-ICP process (Trion Phantom; ICP@500W, RIE@125W) where there is a 180 sec exposure to 50 seem SFe, 30 seem O2, lOsccm CF4, 25 seem Ar at 30 mTorr.

[0180] After Step 4 is completed, the ITO surface and the PDL that are not protected by the photoresist blocks are exposed.

[0181] Step 5: An -180 nm thick vertical encapsulation layer is uniformly (no masking or patterning) deposited using a fluorocarbon based RIE-ICP process. The process was 60 sec of exposure to 50 seem C4F8 (octafluorocyclobutane) at 250 mTorr (ICP@500W; RIE@75W).

[0182] Step 6: The horizontal portions of the vertical encapsulation layer are removed using an oxygen based RIE-ICP process. At the same time, the photoresist blocks over the columns of green OLED pixels are removed. The process was 98 seem O2 at 30 mTorr for 30 sec. The vertical portions remain since this removal process is anisotropic and does not affect the vertical sidewalls. This step also cleans the exposed electrode segments in preparation for the next step

[0183] After Step 6 is completed, the surface of the device has every third column of fully encapsulated green-emitting pixels, with the remaining columns of exposed bottom electrode segments separated by the PDL.

[0184] Steps 7-11: Steps 2-6 were repeated except that a two-stack tandem red OLED materials layer was used instead of green and the protective photoresist block was patterned over a second set of every third column of bottom electrodes, i.e. columns 2, 5, 8, etc. After Step 11 was completed, a second set of columns of fully encapsulated red-emitting pixels was created and a final set of columns, i.e. columns 3, 6, 9, etc., of bottom electrode exposed.

[0185] At the end of the process, a two-color pixelated OLED is formed. It is not a display since the pixels share common electrodes and are not independently controlled. The OLED was unaffected after soaking in acetone for 20 min, CD-26 photoresist developer for 20 min, and P2000 solvent for 20 min. This demonstrates that the individual pixels of the OLED are fully encapsulated. The fact that the green pixels are unaffected after undergoing the red pixeldeposition process, showed that additional colors of pixels (e.g. a column of blue pixels) could be added to this process.

[0186] In the above description, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration, specific embodiments which may be practiced. These embodiments are described in detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that structural, logical and electrical changes may be made without departing from the scope of the present invention. The description of any example embodiments is, therefore, not to be taken in a limiting sense. Although the present invention has been described for the purpose of illustration, it is understood that such detail is solely for that purpose and variations can be made by those skilled in the art without departing from the spirit and scope of the invention.Parts List

[0187] , 10 Substrate

[0188] , 3’, 3” Bottom Electrode Segments

[0189] A Photoresist

[0190] B Hardened Photoresist

[0191] 1stOLED material

[0192] 2ndOLED material

[0193] 1 3rdOLED material

[0194] 2 Non-conductive Material

[0195] 3, 205 Common Top Electrode

[0196] 4, 210 Common Encapsulation Layer

[0197] 0, 30’, 30” Bottom Electrode Segments

[0198] 0 Pixel Definition Layer (PDL)

[0199] 0 OLED Materials Layer of a 1stColor above Bottom Electrode 30 0 Top Electrode above Bottom Electrode 30

[0200] 0 Horizontal Encapsulation Layer above Bottom Electrode 30 00, 102, 104 Patterned Protective Photoresist Block

[0201] 10 First Vertical Encapsulation Layer

[0202] 20 OLED Materials Layer of a 2ndColor above Bottom Electrode 30’ 30 Top Electrode above Bottom Electrode 30’

[0203] 40 Horizontal Encapsulation Layer above Bottom Electrode 30’ 50 Second Vertical Encapsulation Layer

[0204] 60 OLED Materials Layer of a 3rdColor above Bottom Electrode 30” 70 Top Electrode above Bottom Electrode 30”

[0205] 80 Horizontal Encapsulation Layer above Bottom Electrode 30” 90 Third Vertical Encapsulation Layer

[0206] 00 Electrically Conductive Layer

[0207] 02 Step Change in Height of the Horizontal Encapsulation Layer 05 Common Top Electrode

[0208] 10 Common Encapsulation Layer

Claims

Claims1. A method for making pixelated OLED displays comprising:- a first step of providing a substrate (10) with a pattern of bottom electrode segments (30, 30’, 30”), each of which are separated by a pixel definition layer (50);- a second step of uniformly forming at least an OLED materials layer (70) for emitting a first color, a top electrode (80), and a horizontal encapsulation layer (90) over all of the bottom electrode segments (30, 30’, 30”) and pixel definition layer (50);- a third step of patterning a protective block (100) over one set of bottom electrode segments (30) but not over the other sets of bottom electrode segments (30’, 30”);- a fourth step of selectively removing the OLED materials layer (70), top electrode (80) and horizontal encapsulation layer (90) over the other sets of bottom electrode segments (30’, 30”) without the protective block (100);- a fifth step of uniformly forming a vertical encapsulation layer (110) over all surfaces; and - a sixth step of selectively removing only the horizontal portions of the vertical encapsulation layer (110) along with the protective block (100) while retaining the vertical portions of the vertical encapsulation layers to create a fully encapsulated pixel that emits a first color over the set of bottom electrode segments (30) that were protected by the protective block (100) in the third step and where the other sets of bottom electrode segments (30’, 30”) that were not protected by the protective block in the third step are exposed.

2. The method of claim 1 wherein steps seven to eleven are added after the sixth step by repeating steps two to six except for using an OLED materials layer (120) for emitting a second color and forming a protective block (102) over a second set of exposed electrode segments (30’) to create fully encapsulated pixels that emit a second color over the bottom electrode segments (30’) protected by the protective block (102) during the repeated steps.

3. The method of claim 2 wherein steps twelve to sixteen are added after step eleven by again repeating steps two to six except for using an OLED materials layer (160) for emitting a third color and forming a protective block (104) over the remaining set of exposed electrode segments (30”) to create fully encapsulated pixels that emit a third color over the bottom electrode segments (30”) protected by the protective block (104) during the repeated steps.

4. The method of any of claims 1-3 wherein the vertical encapsulation layer (110, 150, 190) is formed using an RIE-ICP process.

5. The method of claim 4 wherein the vertical encapsulation layer (110, 150, 190) is a fluorocarbon.

6. The method of claim 5 where the fluorocarbon vertical encapsulation layer (110, 150, 190) is derived from a fluorocarbon precursor with 4 or less carbon atoms.

7. The method of claim 6 where the fluorocarbon precursor includes CF4, C2F4, C2F6, C3F6, C3F8, C4F8 or C4F10.

8. The method of any of claims 1-3 wherein the removal of the horizontal portions of vertical encapsulation layer (110, 150, 190) and the protective block (100, 102, 104) uses an anisotropic RIE-ICP process using O2.

9. The method of any of claims 1-3 where the step of selectively removing the OLED materials layer (70), top electrode (80) and horizontal encapsulation layer (90) further comprises a two-stage process where a first stage is removing the horizontal encapsulation layer (90, 140, 180) and top electrode (80, 130, 170) and a second stage is removing the OLED materials layer (70, 120, 160).

10. The method of claim 9 wherein the first stage to remove the horizontal encapsulation layer (90, 140, 180) and top electrode (80, 130, 170) uses an RIE-ICP process.

11. The method of claim 10 where the RIE-ICP process of the first stage uses CCI4+BCI3 with or without argon.

12. The method of claim 10 where the RIE-ICP process of the first stage is further divided into two phases, wherein the first phase uses CF4+CHF3+O2 with or without argon and the second phase uses CCI4+BCI3 with or without argon.

13. The method of claim 9 where the second stage of removing the OLED materials layer (70, 120, 160) is by a RIE-ICP process using SFe with or without O2, CF4, or argon in any combination.

14. The method of any of claims 1-3 wherein the step of uniformly forming an OLED materials layer(s) (70, 120, 170) is by vapor deposition.

15. The method of any of claims 1-3 wherein the protective block is formed of a hardened photoresist.

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