Method and apparatus for organic light emitting diode display structure

Abstract

Methods and apparatus for forming organic light emitting diode (OLED) structures disposed on a substrate are provided. In one embodiment, a method for forming an organic light emitting diode (OLED) substrate is provided, the method comprising: forming a first conductive layer on a substrate in a first direction; forming a dielectric layer on a portion of the first conductive layer, wherein the dielectric layer comprises a well that exposes a portion of the first conductive layer; depositing an organic material continuously in the well and on the dielectric layer in a second direction and between two bus bars; and forming a second conductive layer continuously on the organic material in a second direction that is orthogonal to the first direction and between two bus bars, wherein the second conductive layer is in direct contact with the bus bars on opposite sides of the second conductive layer; and depositing an encapsulation layer continuously on the second conductive layer in the second direction and completely covering the second conductive layer.

Description

Background Technology Technical Field

[0002] Embodiments of this disclosure generally relate to methods and apparatus for forming organic light-emitting diode (OLED) display structures, and more specifically, to forming OLED display structures using linear photolithography patterning.

[0003] Description of related technologies

[0004] Displays using organic light-emitting diodes (OLEDs) have recently gained significant attention in display applications compared to liquid crystal displays (LCDs) due to their faster response times, wider viewing angles, higher contrast ratios, lighter weight, lower power consumption, and ease of fabrication on flexible substrates. However, conventionally, the formation of red, green, and blue subpixels requires multiple fine metal masking processes, which limits pixel density and makes them difficult to use in large-size displays. Photolithographic patterning has been proposed to overcome the limitations imposed by fine metal masking processes. In conventional photolithographic patterning, “dot” patterning with full OLED stack deposition and pixelation encapsulation is used to form red, green, and blue subpixels, and requires additional cathode contact process steps to provide a common bus and a cathode for each subpixel. For example, in conventional “dot” patterning, portions of individual subpixels are masked, isolating the cathode of each subpixel from the cathodes of other subpixels, and requiring additional cathode contact processes to connect the cathodes to a common bus.

[0005] Therefore, there is a need for improved methods and equipment for forming OLED display structures. Summary of the Invention

[0006] Methods and apparatus for forming an organic light-emitting display structure disposed on a substrate are provided. In one embodiment, a method for forming an organic light-emitting diode (OLED) display structure is described, the method comprising depositing two busbars on a substrate in a first direction. The method includes: depositing a first conductive layer as a plurality of discrete islands on the substrate in a second direction relative to the first direction; depositing a dielectric layer on a portion of the first conductive layer, wherein the dielectric layer includes a well that exposes a portion of the first conductive layer. The method includes: continuously depositing an organic light-emitting material into the well and onto the dielectric layer in the second direction and between the two busbars; and continuously depositing a second conductive layer on the organic light-emitting material in the second direction and between the two busbars, wherein the second conductive layer is in direct contact with each of the busbars on opposite sides of the second conductive layer. The method includes depositing an encapsulation layer on the second conductive layer in the second direction and completely covering the boundary of the second conductive layer.

[0007] In another embodiment, an organic light-emitting diode (OLED) substrate is disclosed, comprising: a first conductive layer formed on a substrate in a first direction; and a dielectric layer disposed on a portion of the first conductive layer, wherein the dielectric layer includes a well. The OLED substrate further comprises: an organic material disposed in the well and on the dielectric layer in a second direction orthogonal to the first direction and between two busbars, and in contact with the first conductive layer; a second conductive layer continuously disposed on the organic material in the second direction and between the two busbars, wherein the second conductive layer directly contacts the busbars on opposite sides of the second conductive layer; and an encapsulation layer continuously disposed on the second conductive layer in the second direction to completely cover the second conductive layer.

[0008] In another embodiment, an organic light-emitting diode (OLED) substrate is disclosed, comprising: an anode layer formed on a substrate in a first direction; a dielectric layer disposed on a portion of the anode layer, wherein the dielectric layer includes a well, wherein a portion of the anode layer is exposed. The OLED substrate further comprises an organic material within the well and in contact with the anode layer, and continuously disposed on the dielectric layer in a second direction. The OLED substrate further comprises a cathode layer disposed on the organic material and disposed as a continuous layer in a second direction orthogonal to the first direction and between two busbars, wherein the cathode layer directly contacts the busbars on opposite sides of the cathode layer at a cathode / busbar interface; and an encapsulation layer continuously disposed on the cathode layer in the second direction to completely cover the second conductive layer. Attached Figure Description

[0009] To gain a more detailed understanding of the features described above, reference can be made to embodiments to obtain a more specific description of the present disclosure, some of which are illustrated in the accompanying drawings. However, it should be noted that the drawings only illustrate typical embodiments of the present disclosure and should therefore not be considered as limiting the scope of the disclosure, as other equivalent embodiments are permissible.

[0010] Figures 1A to 1C Various views are a portion of a display according to embodiments disclosed herein. Figure 1A It is a planar view of the pixel sub-regions of the display, and Figure 1B and Figure 1C They are along Figure 1A Line 1B-1B and Figure 1AA cross-sectional view of a portion of the display of line 1C-1C.

[0011] Figure 2A It is a plan view of the pixel sub-regions of a display according to another embodiment.

[0012] Figure 2B and Figure 2C Along the different stages of the formation process Figure 2A A cross-sectional view of a portion of the display line 2B-2B.

[0013] Figure 3A It is a plan view of the pixel sub-regions of a display according to another embodiment.

[0014] Figure 3B It is along Figure 3A A cross-sectional view of the display with line 3B-3B.

[0015] For ease of understanding, the same reference numerals have been used as much as possible to indicate common elements in the figures. It is contemplated that elements and features of one embodiment can be advantageously combined in other embodiments without further explanation. Detailed Implementation

[0016] This disclosure provides methods and apparatus for forming organic light-emitting display structures on a substrate.

[0017] Figures 1A to 1C These are various views of the display 100 according to the embodiments disclosed herein. Figure 1A It is a plan view of the active area 102 of the display 100, and Figure 1B and Figure 1C They are along Figure 1A Line 1B-1B and Figure 1A A cross-sectional view of a portion of the active region 102 of line 1C-1C.

[0018] like Figure 1AAs shown, the display 100 includes an active region 102 located between two busbars 104 in a peripheral region 105 (e.g., a non-active region) extending in a first direction and on opposite sides (or ends) of the display 100. The active region 102 of the display 100 includes a plurality of pixel columns 106A-106D extending along the first direction, each pixel column including a plurality of subpixels shown as subpixels 108A (e.g., red), subpixels 108B (e.g., green), and subpixels 108C (e.g., blue). Although not shown, a plurality of pixels (such as pixel columns 106A-106D having subpixels 108A-108C) are repeated on the display 100. For example, if the resolution of the display 100 is 1920×1080, then in each of the 1080 pixel columns there will be 1920 subpixels 108A, 1920 subpixels 108B, and 1920 subpixels 108C.

[0019] If rows 110A-C extend in a second direction that is generally orthogonal to the first direction, then the color of each of one or more sub-pixels in multiple pixel columns 106A-106D is extended. Typically, orthogonality can be defined as greater than 45 degrees up to and including 90 degrees. For example, here the sub-pixels in columns 106A-106D extend in the same row (rows 110A-110C), and organic material for all sub-pixels in the same row in at least a single active region is deposited into separate wells for the sub-pixels of said row using thermally evaporated OLED material.

[0020] In a specific example, all sub-pixels 108A in row 110A are formed by depositing organic material through a grooved lithographic pattern having linear slots extending in a second direction in row 110A, while the same lithographic pattern covers the sub-pixel regions of rows 110B and 110C to prevent the deposited organic material from reaching the locations of the sub-pixel regions. This lithographic pattern also extends to the overlapping busbars. A mask with an opening larger than the entire active region 102 is used to prevent the organic light-emitting layer deposition from directly contacting the busbars, but the mask is not used for the second conductive layer, or a different mask is used for the second conductive layer, which allows the second conductive layer to directly contact the busbars. This type of mask is sometimes referred to as an "open mask" because the mask does not individually assign the delivery of organic material to individual sub-pixel locations, but rather allows it to occur in the region between individual sub-pixel locations. Similarly, all sub-pixels 108B in row 110B are deposited using another slotted lithographic mask pattern having slots extending in a second direction along row 110B, while the same lithographic pattern covers rows 110A and 110C. In the same manner, all sub-pixels 108C in row 110C are deposited using another slotted lithographic mask pattern having slots along the direction of row 110C, while the same lithographic pattern covers rows 110A and 110B. The scan direction 111 of the OLED source material (a first direction (relative to the Y direction of display 100)) is generally parallel to the first direction extending from rows 110A-110C. Subpixels located in other active regions of display 100 are... Figure 1A The active region 102 shown and described is similarly deposited. During deposition (scanning), the open mask is stationary relative to the substrate 112, and the OLED material source scans over the substrate 112.

[0021] This manufacturing method differs from conventional photolithographic OLED patterning methods that use "dot-shaped" photolithographic patterns with fine openings for each sub-pixel. Using a grooved photolithographic pattern for each deposition step as disclosed herein eliminates the need for additional cathode contact processes because the cathodes of each sub-pixel are "connected" together and directly contact the busbar. Other properties of the active region 102 as described herein by the grooved photolithographic pattern will be described below.

[0022] like Figure 1B and Figure 1CAs shown, sub-pixel 108B is shown in cross-section. Sub-pixel 108B is formed on substrate 112. A plurality of anodes 114 (first conductive layer) are formed on substrate 112. Each anode 114 is associated with a discrete sub-pixel (such as each of sub-pixels 108A-108C). The anodes 114 are formed as discrete conductive islands, each conductive island overlapping or within its associated sub-pixel. Each anode 114 is also electrically connected to a thin-film transistor (not shown) on substrate 112, which provides current to each OLED device. The anodes 114 can be transparent or reflective, depending on whether the display 100 will be used as a bottom-emitting display or a top-emitting display.

[0023] A pixel defining layer 116 (dielectric layer) is formed on the anode 114 and includes a plurality of wells 120 formed to extend through the pixel defining layer 116, the pixel defining layer 116 providing the boundaries of the wells 120. Figure 1B In the cross-sectional view, a portion of the pixel defining layer 116 is defined at the boundary or opposite side of the wells 120 spaced apart from each other in a first direction and is occupied by the OLED material 118. The pixel defining layer 116 is a dielectric material, such as silicon nitride (SiNx), silicon oxide (SiOx), or other electrically insulating materials.

[0024] The individual wells 120 of the pixel defining layer 116 and the openings for the cathode / bus interface 136 are formed by an etching process, for example by etching through a patterned mask or patterned photoresist layer, which is then removed and the substrate is cleaned. A sacrificial layer 124 is then deposited as a capping film over at least the active region 102, typically over the entire substrate, to cover the pixel defining layer, and a photoresist layer 126 is formed over the sacrificial layer 124. Openings 122 are formed through the photoresist layer 126, and the opening area of ​​each opening in the second direction (X direction) is typically larger than the opening area of ​​each individual well 120 formed in the pixel defining layer 116 and the second direction (X direction) to extend over the location of the bus 104. A wet etchant is introduced to isotopically etch away a portion of the sacrificial layer 124 covering each region forming the well 120, such that a portion of the sacrificial layer 124 covering each region forming the well 120 is removed to expose the surface of the pixel defining layer 116 and the anode 114 exposed at the bottom of the well 120. An opening in the sacrificial layer 124 extends beneath a portion of the photoresist layer 126 at each well 120 location, thereby leaving an overhang of the photoresist layer 126 at each well 120 location. The opening 122 extends over multiple wells 120 in a row of active regions 102. For example, Figure 1A The boundary of each row 110A-110C is the boundary of opening 122.

[0025] After cleaning the substrate, to remove byproducts of the etching process, OLED material is deposited as a continuous layer through opening 122, and thus deposited on the portion of pixel defining layer 116 extending between wells 120, and on top of individual wells 120 and 126. Then, cathode 128 (e.g., a second conductive layer) is deposited as a continuous layer through opening 122 on top of OLED material 118 in each well 120 and on the portion of pixel defining layer 116 between cathode 128 and OLED material 118, and is electrically separated (insulated) from anode 114 by pixel defining layer 116. As used herein, the term “continuous” or “continuously” can be defined as a conformal uninterrupted layer deposited through a slot lithographic pattern having linear slots extending in a second direction as described herein.

[0026] By using a directional deposition method, such as thermal evaporation or sputtering (physical vapor deposition) or a combination of both, to deposit one or more conductive materials through openings 122, the overhanging portion of the photoresist layer 126 is allowed to limit the lateral extent of the conductive material in the first and second directions. However, by appropriately setting the opening size with respect to the directional dispersion relative to the deposition method, the conductive material of the cathode 128 extends over the entire OLED material 118 in each well, and in some cases beyond the sides of the OLED material 118, depositing the periphery of the OLED material 118 immediately adjacent to each well 120 directly onto the pixel defining layer to help isolate the OLED material 118. In one embodiment, both the OLED material and the cathode 128 are deposited using the directional deposition method described above. However, the cathode 128 does not need to extend over the OLED material 118.

[0027] An encapsulation layer 130 is continuously formed over the pixel defining layer 116, the OLED material 118, and the cathode 128. The encapsulation layer 130 prevents moisture from entering the opening 122. In some embodiments, the encapsulation layer 130 is SiNx or plasma-polymerized hexamethyldisiloxane (pp-HMDSO). The sacrificial layer 124 (and other layers above the photoresist layer 126) is then removed. For rows having sub-pixels 108A, 108B, and 108C respectively, the above process is typically repeated three times to form a full-color display.

[0028] exist Figure 1CIn the cross-sectional view, the extended length of the cathode 128 provides electrical communication with at least one of the busbars 104. For example, the busbars 104 are directly connected to the cathode 128 at the cathode / busbar interface 136. This direct electrical connection differs from conventional dot-matrix patterned OLED devices because it eliminates the need for separate electrical contact pads used in conventional devices. In conventional devices, a separate step is required to form the electrical contact pads (e.g., metal plates, foils, or films) to complete the electrical connection between the cathode and the busbar. However, the device described herein eliminates this additional electrical contact step.

[0029] In some implementations, the OLED material may overlap and directly contact the surface of the busbar. If the OLED material contacts the busbar, a laser drilling process is applied prior to cathode deposition to remove the OLED material from the busbar for cathode deposition. Therefore, the cathode will be in direct contact with the busbar.

[0030] refer to Figure 1B and Figure 1C The photolithographic patterns and processes used to form the display 100 as described herein provide a more robust display and reduce the number of process steps. In addition to eliminating the additional electrical contact pad steps described above, the OLED material overlay (deposited as red, green, and blue stripes in each active region 102, respectively) naturally conforms to the shape of the well 120 and is discontinuous outside the tapered region 140 surrounding the well 120.

[0031] Figure 2A-2C These are various different views of a part of a display 200 according to another embodiment. Figure 2A This is a plan view of the active area 202 of the display 200, and Figure 2A and Figure 2C It is along Figure 2A A cross-sectional view of a portion of the active region 202 of line 2B-2B. Figure 2B A portion of the display 200 during its formation process is shown, while Figure 2C A portion of the display 200 is shown as a finished product with a transparent conductive layer 212. The transparent conductive layer 212 can be deposited as a capping layer over the entire active region 202 and the two busbars 104.

[0032] Similar to Figures 1A to 1C In the illustrated embodiment, the active region 202 is located between two busbars 104 on opposite sides of the active region 202. For simplicity, further explanation will not be provided. Figures 1A to 1C The description in Figures 2A to 2C Common reference numerals appearing in the figures.

[0033] In this embodiment, additional conductive paths are added to the display 200 and are shown as a plurality of conductive layers 204 (e.g., a third conductive layer or multiple layers). Each of the plurality of conductive layers 204A-204C is located between busbars 104. Each of the plurality of conductive layers 204A-204C is spaced apart from each other and spaced apart from the busbars 104. Each of the plurality of conductive layers 204A-204C is configured to provide current and / or voltage to individual sub-pixels 108A, 108B, and 108C.

[0034] An example of current flowing through one of the multiple conductive layers 204A-204C is indicated by dashed arrow 206. As shown, an input current is supplied to one of the conductive layers 204C. The input current signal flows to the electrical contact 208 on the conductive layer 204C, and then through the transparent conductive layer 212 to the contact 210 on the busbar 104. The signal is then distributed along the busbar 104, providing current to each sub-pixel 108A, sub-pixel 108B, and sub-pixel 108C on the pixel column 106D, and to all sub-pixels on columns 106A-106C.

[0035] Display 200 includes located Figure 2C The transparent conductive layer 212 is shown above the electrical contact 208 and the contact 210 on the busbar. The transparent conductive layer 212 provides electrical connection between the electrical contact 208 and the contact 210 on the busbar. After removing the sacrificial layer 124 and the photoresist layer 126 (both on... Figure 1B and 1C (As shown in the diagram) a transparent conductive layer 212 is then deposited. The transparent conductive layer 212 may be indium tin oxide (ITO), indium zinc oxide (IZO), or other transparent conductive materials. The transparent conductive layer 212 can be advantageously used in top-emitting displays. The transparent conductive layer 212 is used to reduce the dynamic voltage (IR) drop in the display 200.

[0036] Figure 3A and 3B These are various different views of a part of a display 300 according to another embodiment. Figure 3A It is a plan view of the active area 302 of the display 300, and Figure 3B It is along Figure 3A A cross-sectional view of a portion of the active region 302 along line 3B-3B. For simplicity, further explanation will not be provided. Figures 1A to 2B The description in Figure 3A and Figure 3B Common reference numerals appearing in the figures.

[0037] In this embodiment, additional electrical contact features are formed on the active region 302, and are shown as a plurality of cathode electrical contacts 304. Each of the plurality of cathode electrical contacts 304 is formed by an additional photolithography process that forms a via through the encapsulation layer 130, thereby exposing the cathode 128. The cathode 128 may consist of more than one layer, such that the upper layer will protect the lower layer during the via formation process. A transparent conductive layer 212 is then formed on the display 300. The plurality of cathode electrical contacts 304 further improve the cathode voltage (IR) drop in the display 300.

[0038] While the foregoing describes embodiments of this disclosure, other and further embodiments of this disclosure may be conceived without departing from the basic scope of this disclosure, and the scope of this disclosure is defined by the scope of the appended claims.

Claims

1. A method for forming an organic light-emitting diode (OLED) display structure, comprising: Two busbars are deposited on the substrate in the first direction; A first conductive layer is deposited on the substrate as a plurality of discrete islands in a second direction relative to the first direction; A dielectric layer is deposited on a portion of the first conductive layer, wherein the dielectric layer includes a well that exposes a portion of the first conductive layer; In the second direction and between the two busbars, organic light-emitting material is deposited into the well and onto the dielectric layer; A second conductive layer is deposited on the organic light-emitting material in the second direction and between the two busbars, wherein the second conductive layer is in direct contact with each of the busbars on the opposite side of the second conductive layer; as well as An encapsulation layer is deposited on the second conductive layer in the second direction to cover the boundary of the second conductive layer.

2. The method of claim 1, wherein an open mask is used during the deposition of the organic light-emitting material to electrically isolate the organic light-emitting material from the busbar.

3. The method of claim 1, wherein each of the first conductive layers is associated with a corresponding sub-pixel.

4. The method of claim 1, wherein each of the first conductive layers surrounds a corresponding well.

5. The method of claim 1, wherein the organic light-emitting material is continuously deposited in the well in the second direction, and the encapsulation layer is continuously deposited on the second conductive layer in the second direction to completely cover the boundary of the second conductive layer.

6. The method of claim 1, further comprising a plurality of third conductive layers formed in the first direction between the two busbars, wherein the organic light-emitting material in the trap comprises a sub-pixel of a plurality of sub-pixels defining a pixel column, and each of the plurality of third conductive layers comprises one or more first electrical contacts coupled to the second conductive layer and positioned between the two pixel columns.

7. The method of claim 6, wherein each of the one or more first electrical contacts is electrically connected to the two busbars via a transparent conductive layer.

8. The method of claim 6, wherein the second conductive layer includes one or more second electrical contacts electrically coupled to the third conductive layer and positioned between two sub-pixels of the pixel column.

9. The method of claim 8, wherein a transparent conductive layer is formed over the one or more first electrical contacts and second electrical contacts.

10. An organic light-emitting diode substrate, comprising: Two busbars are formed on the substrate in a first direction; A first conductive layer is formed on the substrate in the first direction; A dielectric layer disposed on the two busbars and a portion of the first conductive layer, wherein the dielectric layer includes a well; A hanging portion, the hanging portion being formed on a portion of the dielectric layer; An organic material, which is located in the well and on the dielectric layer in a second direction relative to the first direction and between the two busbars, and is in contact with the first conductive layer; A second conductive layer is disposed on the organic material in the second direction and between the two busbars, wherein the second conductive layer is in direct contact with each of the busbars on opposite sides of the second conductive layer; as well as An encapsulation layer is on the second conductive layer in the second direction to cover the second conductive layer.

11. The organic light-emitting diode substrate of claim 10, wherein the second direction is substantially orthogonal to the first direction.

12. The organic light-emitting diode substrate of claim 10, wherein the first conductive layer comprises a plurality of discrete conductive islands, each discrete conductive island being associated with a corresponding well.

13. The organic light-emitting diode substrate as claimed in claim 10, wherein: The organic light-emitting material is continuously disposed in the well in the second direction. The second conductive layer is continuously disposed on the organic material in the second direction, and The encapsulation layer is continuously disposed on the second conductive layer in the second direction to completely cover the second conductive layer.

14. The organic light-emitting diode substrate of claim 10, further comprising a plurality of third conductive layers formed in the first direction between the two busbars, wherein the organic material in the well comprises a sub-pixel of a plurality of sub-pixels defining a pixel column, and each of the plurality of third conductive layers comprises one or more first electrical contacts coupled to the second conductive layer and positioned between the two pixel columns.

15. The organic light-emitting diode substrate of claim 14, wherein the second conductive layer includes one or more second electrical contacts, the second electrical contacts being coupled to the third conductive layer and positioned between two sub-pixels of the pixel column.

16. The organic light-emitting diode substrate of claim 15, wherein a transparent conductive layer is formed over the one or more first electrical contacts and second electrical contacts.

17. An organic light-emitting diode substrate, comprising: Two busbars are formed on a substrate in a first direction; An anode layer, the anode layer being formed on the substrate in the first direction; A dielectric layer disposed on the two busbars and a portion of the anode layer, wherein the dielectric layer includes a well, and wherein a portion of the anode layer is exposed; A hanging portion, the hanging portion being formed on a portion of the dielectric layer; An organic material, wherein the organic material is in the well and in contact with the anode layer in a second direction orthogonal to the first direction and is on the dielectric layer; A cathode layer is disposed on the organic material in the second direction and between the two busbars, wherein the cathode layer is in direct contact with the busbars on its opposite side at the cathode / busbar interface; as well as An encapsulation layer is disposed on the cathode layer in the second direction to cover the cathode layer.

18. The organic light-emitting diode substrate of claim 17, wherein the width of the cathode in the first direction is substantially equal to the width of the organic material in the first direction.

19. The organic light-emitting diode substrate of claim 17, wherein the width of the cathode in the second direction is significantly greater than the width of the organic material in the second direction.

20. The organic light-emitting diode substrate of claim 17, wherein the organic light-emitting diode substrate further comprises a plurality of conductive layers formed in the first direction between the two busbars.

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