WO2024226139A1

WO2024226139A1 - Multiple overhang to enhanced pixel encapsulation

Info

Publication number: WO2024226139A1
Application number: PCT/US2024/014707
Authority: WO
Inventors: Yu-Hsin Lin; Chung-Chia Chen; Jungmin Lee
Original assignee: Applied Materials, Inc.
Priority date: 2023-04-25
Filing date: 2024-02-07
Publication date: 2024-10-31

Abstract

Embodiments described herein relate to a device including a substrate, a plurality of overhang structures, and a plurality of sub-pixels. The plurality of overhang structures include a first structure, a second structure disposed over an upper surface of the first structure, adjacent first overhangs, a third structure disposed over the second structure, and adjacent second overhangs. Each first overhang is defined by a first overhang extension of the second structure extending laterally past an upper surface of the first structure. Each sub-pixel includes an anode, an organic light emitting diode (OLED) material disposed over the anode, and a cathode disposed over the OLED material.

Description

MULTIPLE OVERHANG TO ENHANCED PIXEL ENCAPSULATION

BACKGROUND

Field

[0001] Embodiments described herein generally relate to a display. More specifically, embodiments described herein relate to sub-pixel circuits and methods of forming sub-pixel circuits that may be utilized in a display such as an organic lightemitting diode (OLED) display.

Description of the Related Art

[0002] Input devices including display devices may be used in a variety of electronic systems. An organic light-emitting diode (OLED) is a light-emitting diode (LED) in which the emissive electroluminescent layer is a film of an organic compound that emits light in response to an electric current. OLED devices are classified as bottom emission devices if light emitted passes through the transparent or semitransparent bottom electrode and substrate on which the panel was manufactured. Top emission devices are classified based on whether or not the light emitted from the OLED device exits through the lid that is added following the fabrication of the device. OLEDs are used to create display devices in many electronics today. Today’s electronics manufacturers are pushing these display devices to shrink in size while providing higher resolution than just a few years ago.

[0003] OLED pixel patterning is currently based on a process that restricts panel size, pixel resolution, and substrate size. Rather than utilizing a fine metal mask, photo lithography should be used to pattern pixels. Currently, OLED pixel patterning requires lifting off organic material after the patterning process. When lifted off, the organic material leaves behind a particle issue that disrupts OLED performance. Accordingly, what is needed in the art are sub-pixel circuits and methods of forming sub-pixel circuits to increase pixel-per-inch and provide improved OLED performance.

SUMMARY

[0004] In one embodiment, a device is provided. The device includes a substrate, a plurality of overhang structures, and a plurality of sub-pixels. The plurality of overhang structures include a first structure, a second structure disposed over an upper surface of the first structure, adjacent first overhangs, a third structure disposed over the second structure, and adjacent second overhangs. Each first overhang is defined by a first overhang extension of the second structure extending laterally past an upper surface of the first structure. Each sub-pixel includes an anode, an organic light emitting diode (OLED) material disposed over the anode, and a cathode disposed over the OLED material.

[0005] In another embodiment, a device is provided. The device includes a substrate, a plurality of overhang structures disposed over the substrate, and a plurality of sub-pixels. Each overhang structure includes a first structure, a second structure disposed over an upper surface of the first structure, adjacent first overhangs, and adjacent second overhangs. The second structure includes an interior plane, an upper surface, an upper sidewall formed between the interior plane and the upper surface, a bottom surface, and a lower sidewall formed between the interior plane and the bottom surface. Each first overhang is defined by a first overhang extension of the second structure extending laterally past an upper surface of the first structure. Each second overhang is formed by the upper sidewall. Each sub-pixel includes an anode, an organic light emitting diode (OLED) material disposed over the anode, and a cathode disposed over the OLED material.

[0006] In another embodiment, a method is provided. The method includes depositing a first structure layer and a second structure layer over a substrate. Portions of the second structure layer exposed by a resist are removed to form a second structure and a third structure. Portions of the first structure layer exposed by the resist are removed to form a first structure. The resist is removed from the third structure. An organic light emitting diode (OLED) material, a cathode, and an encapsulation layer is deposited.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only exemplary embodiments and are therefore not to be considered limiting of its scope, and may admit to other equally effective embodiments. [0008] Figure 1A is a schematic, cross-sectional view of a sub-pixel circuit, according to embodiments.

[0009] Figure 1 B is a schematic, cross-sectional view of an overhang structure of a sub-pixel circuit, according to embodiments.

[0010] Figure 1 C is a schematic, cross-sectional view of a sub-pixel circuit, according to embodiments.

[0011] Figure 1 D is a schematic, cross-sectional view of an overhang structure of a sub-pixel circuit, according to embodiments.

[0012] Figure 2 is a schematic, cross-sectional view of an overhang structure of a sub-pixel circuit, according to embodiments.

[0013] Figure 3 is a schematic, cross-sectional view of an overhang structure of a sub-pixel circuit, according to embodiments.

[0014] Figures 4 is a schematic, cross-sectional view of an overhang structure of a sub-pixel circuit, according to embodiments.

[0015] Figure 5 is a schematic, cross-sectional view of an overhang structure of a sub-pixel circuit, according to embodiments.

[0016] Figure 6 is a schematic, cross-sectional view of an overhang structure of a sub-pixel circuit, according to embodiments.

[0017] Figure 7 is a flow diagram of a method 700 for forming a sub-pixel circuit

[0018] Figure 8A-8D are schematic, cross-sectional views of a substrate during the method for forming the sub-pixel circuit.

[0019] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation. DETAILED DESCRIPTION

[0020] Embodiments described herein generally relate to a display. More specifically, embodiments described herein relate to sub-pixel circuits and methods of forming sub-pixel circuits that may be utilized in a display such as an organic lightemitting diode (OLED) display. In various embodiments, the sub-pixels employ advanced overhang structures to improve functionality of the display.

[0021] Each of the embodiments described herein of the sub-pixel circuit include a plurality of sub-pixels with each of the sub-pixels defined by adjacent overhang structures that are permanent to the sub-pixel circuit. While the Figures depict two sub-pixels with each sub-pixel defined by adjacent overhang structures, the sub-pixel circuit of the embodiments described herein include a plurality of sub-pixels, such as two or more sub-pixels. Each sub-pixel has OLED materials configured to emit a white, red, green, blue or other color light when energized. E.g., the OLED materials of a first sub-pixel emits a red light when energized, the OLED materials of a second sub-pixel emits a green light when energized, and the OLED materials of a third subpixel emits a blue light when energized.

[0022] The overhangs are permanent to the sub-pixel circuit and include at least a second structure disposed over a first structure. The adjacent overhang structures defining each sub-pixel of the sub-pixel circuit of the display provide for formation of the sub-pixel circuit using evaporation deposition and provide for the overhang structures to remain in place after the sub-pixel circuit is formed. Evaporation deposition is utilized for deposition of OLED materials (including a hole injection layer (HIL), a hole transport layer (HTL), an emissive layer (EML), and an electron transport layer (ETL)) and cathode. In some instances, an encapsulation layer may be disposed via evaporation deposition. In embodiments including one or more capping layers, the capping layers are disposed between the cathode and the encapsulation layer. The encapsulation layer of a respective sub-pixel is disposed over the cathode.

[0023] Figure 1A is a schematic, cross-sectional view of a first sub-pixel circuit 100A. Figure 1 B is a schematic, cross-sectional view of an overhang structure 110 of the first sub-pixel circuit 100A. The first sub-pixel circuit 100A includes a substrate 102. Metal-containing layers 104 may be patterned on the substrate 102 and are defined by adjacent pixel structures (PS) 126A disposed on the substrate 102. In one embodiment, the PS 126A are disposed on the substrate 102. In one embodiment, the metal-containing layers 104 are pre-patterned on the substrate 102. E.g., the substrate 102 is pre-patterned with metal-containing layers 104 of indium tin oxide (ITO). The metal-containing layers 104 are configured to operate as anodes of respective sub-pixels. In one embodiment, the metal-containing layer 104 is a layer stack of a first transparent conductive oxide (TCO) layer, a second metal-containing layer disposed on the first TCO layer, and a third TCO layer disposed on the second metal-containing layer. The metal-containing layers 104 include, but are not limited to, chromium, titanium, gold, silver, copper, aluminum, ITO, a combination thereof, or other suitably conductive materials.

[0024] The plurality of PS 126A are disposed over the substrate 102. The PS 126A include one of an organic material, an organic material with an inorganic coating disposed thereover, or an inorganic material. The organic material of the PS 126A includes, but is not limited to, polyimides. The inorganic material of the PS 126A includes, but is not limited to, silicon oxide (SiC>2), silicon nitride (SisN4), silicon oxynitride (Si₂N₂O), magnesium fluoride (MgF2), or combinations thereof. Adjacent PS 126A define a respective sub-pixel and expose the anode (i.e., metal-containing layer 104) of the respective sub-pixel circuit 100.

[0025] The first sub-pixel circuit 100A has a plurality of sub-pixels 106 including at least a first sub-pixel 108A and a second sub-pixel 108B. While the Figures depict the first sub-pixel 108A and the second sub-pixel 108B, the first sub-pixel circuit 100A of the embodiments described herein may include two or more sub-pixels 106, such as a third and a fourth sub-pixel. Each sub-pixel 106 has OLED materials configured to emit a white, red, green, blue or other color light when energized. E.g., the OLED materials of the first sub-pixel 108A emits a red light when energized, the OLED materials of the second sub-pixel 108B emits a green light when energized, the OLED materials of a third sub-pixel emits a blue light when energized, and the OLED materials of a fourth sub-pixel emits another color light when energized.

[0026] Each sub-pixel 106 includes an overhang structure 110. The overhang structures 110 are permanent to the first sub-pixel circuit 100A. The overhang structures 110 further define each sub-pixel 106 of the first sub-pixel circuit 100A. Each overhang structure 110 includes adjacent first overhangs 117 and adjacent second overhangs 109. The adjacent first overhangs are defined by a first overhang extension 117A (as shown in Figure. 1 B) of a second structure 11 OB extending laterally past an upper surface 105 of a first structure 110A. The first structure 110A is disposed over an upper surface 103 (as shown in Figure. 1 B) of the plurality of adjacent PS 126A. The adjacent second overhangs 109 are defined by a second overhang extension 109A (as shown in Figure 1 B) of a third structure 110C extending laterally past the upper surface 115 of the second structure 110B. The third structure 110C is disposed over the second structure 110B.

[0027] In one embodiment, the second structure 11 OB and third structure 110C include a non-conductive inorganic material and the first structure 110A includes a conductive inorganic material. The conductive materials of the first structure 110A include aluminum (Al), aluminum neodymium (AINd), molybdenum (Mo), molybdenum tungsten (MoW), copper (Cu), or combinations thereof. The inorganic materials of the second structure 11 OB and third structure 110C include titanium (Ti), silicon nitride (S isN4), silicon oxide (S iC>2) , silicon oxynitride (Si2N2O), or combinations thereof. The overhang structures 110 are able to remain in place, i.e., are permanent. In one embodiment, the first structure 110A includes a metal containing material. In one example, the metal-containing material is a transparent conductive oxide (TCO) material. The TCO material includes, but is not limited to, indium zinc oxide (IZO), indium tin oxide (ITO), indium gallium zinc oxide (IGZO), or combinations thereof. In another embodiment, the first structure 110A, the second structure 110B, and third structure 110C include a conductive material.

[0028] Adjacent first overhangs 117 are defined by a first overhang extension 117A. At least a bottom surface 107 of the second structure 110B is wider than the upper surface 105 of a first structure 110A to form the first overhang extension 117A. The first overhang extension 117A of the second structure 110B forms the first overhang 117 and allows for the second structure 110B to shadow the first structure 110A. The shadowing of the first overhang 117 provides for evaporation deposition of OLED materials 112 and a cathode 114. The OLED materials 112 may include one or more of a HIL, a HTL, an EML, and an ETL. The OLED material is disposed over and in contact with the metal-containing layer 104. The OLED material 112 is disposed under adjacent first overhang 117. The cathode 114 includes a conductive material, such as a metal. E.g., the cathode 114 includes, but is not limited to, silver, magnesium, chromium, titanium, aluminum, ITO, or a combination thereof. The cathode 114 is disposed over the OLED material 112 and a sidewall of the second structure 110B of the overhang structures 110.

[0029] Adjacent second overhangs 109 are defined by a second overhang extension 109A of the third structure 110C. At least a bottom surface 121 of the third structure 110C is wider than an upper surface 115 of the second structure 110B to form the second overhang extension 109A of the second overhang 109. The third structure 110C is disposed over the upper surface 115 of the second structure 110B. The second overhang extension 109A of the third structure 110C forms the second overhang 109 and allows for the third structure 110C to shadow the second structure 110B. The shadowing of the second overhang 109 provides for evaporation deposition of each of the OLED material 112 and the cathode 114. Each of the OLED material 112 and the cathode 114 are disposed under the second overhang 109.

[0030] The cathode 114 includes a conductive material, such as a metal. E.g., the cathode 114 includes, but is not limited to, silver, magnesium, chromium, titanium, aluminum, ITO, or a combination thereof. In one embodiment, material of the cathode 114 is different from the material of the first structure 110A, the second structure 110B, and the third structure 110C. In some embodiments, the OLED material 112 and the cathode 114 are disposed on the sidewall 111 of the first structure 110A. The OLED material 112 and the cathode 114 are not disposed over the sidewall 123 of the second structure 110B or the sidewall 124 of the third structure 110C.

[0031] Each sub-pixel 106 includes an encapsulation layer 116. The encapsulation layer 116 may be or may correspond to a local passivation layer. The encapsulation layer 116 of a respective sub-pixel is disposed over the cathode 114 (and OLED material 112) with the encapsulation layer 116 extending under at least a portion of each of the first overhangs 117 and the second overhangs 109. The encapsulation layer 116 includes the non-conductive inorganic material, such as the silicon-containing material. The silicon-containing material may include SisN4 containing materials.

[0032] In embodiments including one or more capping layers, the capping layers are disposed between the cathode 114 and the encapsulation layer 116. E.g., a first capping layer and a second capping layer are disposed between the cathode 114 and the encapsulation layer 116. Each of the embodiments described herein may include one or more capping layers disposed between the cathode 114 and the encapsulation layer 116. The first capping layer may include an organic material. The second capping layer may include an inorganic material, such as lithium fluoride. The first capping layer and the second capping layer may be deposited by evaporation deposition. In another embodiment, the first sub-pixel circuit 100A further includes at least a global passivation layer 120 disposed over the overhang structure 110 and the encapsulation layer 116. In yet another embodiment, the sub-pixel includes an intermediate passivation layer disposed over the overhang structures 110 of each of the sub-pixels 106, and disposed between the encapsulation layer 116 and the global passivation layer 120.

[0033] The encapsulation layer 116 is disposed within the adjacent second overhangs 109. The adjacent second overhangs 109 thus provide for decreased moisture invasion of the overhang structures 110. The adjacent second overhangs 109 create a more complex invasion path for moisture due to the contact between the encapsulation layer 116 and the second structure 110B. As moistures invades the overhang structures 110, the encapsulation layer 116 within the adjacent second overhangs 109 creates a barrier between the moisture and the second structure 110B, preventing the moisture from invading the adjacent first overhangs 117.

[0034] Figure 1 C is a schematic, cross-sectional view of a second sub-pixel circuit 100B according to embodiments. Figure 1 D is a schematic, cross-sectional view of the second sub-pixel circuit 100B according to embodiments. The second sub-pixel circuit 100B includes a substrate 102. A base layer 125 may be patterned over the substrate 102. The base layer 125 includes, but is not limited to, a CMOS layer. Metal-containing layers 104 (e.g., anodes) may be patterned on the base layer 125 and are defined by adjacent pixel structures (PS) 126B disposed on the substrate 102. In one embodiment, the metal-containing layer 104 are pre-patterned on the base layer 125. E.g., the base layer 125 is pre-patterned with metal-containing layer 104 of indium tin oxide (ITO). The metal-containing layer 104 may be disposed on the substrate 102. The metal-containing layer 104 is configured to operate as an anode of respective sub-pixels. In one embodiment, the metal-containing layer 104 is a layer stack of a first transparent conductive oxide (TCO) layer, a second metal-containing layer disposed on the first TCO layer, and a third TCO layer disposed on the second metal-containing layer. The metal-containing layer 104 include, but are not limited to, chromium, titanium, gold, silver, copper, aluminum, ITO, a combination thereof, or other suitably conductive materials.

[0035] The PS 126B are disposed over the substrate 102. The PS 126B may be disposed on the base layer 125. The PS 126B include one of an organic material, an organic material with an inorganic coating disposed thereover, or an inorganic material. The organic material of the PS 126B includes, but is not limited to, polyimides. The inorganic material of the PS 126B includes, but is not limited to, silicon oxide (SiC>2), silicon nitride (SisN4), silicon oxynitride (Si₂N₂O), magnesium fluoride (MgF2), or combinations thereof. Adjacent PS 126B define a respective subpixel and expose the metal-containing layer 104 of the respective second sub-pixel circuit 100B.

[0036] The second sub-pixel circuit 100B has a plurality of sub-pixel lines (e.g., first sub-pixel line 106A and second sub-pixel line 106B). The sub-pixel lines are adjacent to each other along the pixel plane. Each sub-pixel line includes at least two sub-pixels. E.g., the first sub-pixel line 106A includes a first sub-pixel 108A and a second sub-pixel (not shown) and the second sub-pixel line 106B includes a third subpixel 108C and a fourth sub-pixel (not shown). While Figure 1A depicts the first subpixel line 106A and the second sub-pixel line 106B, the second sub-pixel circuit 100B of the embodiments described herein may include two or more sub-pixel lines, such as a third sub-pixel line and a fourth sub-pixel. Each sub-pixel line has OLED materials configured to emit a white, red, green, blue or other color light when energized. E.g., the OLED materials of the first sub-pixel line 106A emits a red light when energized, the OLED materials of the second sub-pixel line 106B emits a green light when energized, the OLED materials of a third sub-pixel line emits a blue light when energized, and the OLED materials of a fourth sub-pixel emits another color light when energized. The OLED materials within a pixel line may be configured to emit the same color light when energized. E.g., the OLED materials of the first subpixel 108A and the second sub-pixel of the first sub-pixel line 106A emit a red light when energized and the OLED materials of the third sub-pixel 108C and the fourth sub-pixel of the second sub-pixel line 106B emit a green light when energized. [0037] Each sub-pixel line includes adjacent overhang structures 110, with adjacent sub-pixel lines sharing the adjacent overhang structures 110. The overhang structures 110 are permanent to the second sub-pixel circuit 100B. The overhang structures 110 further define each sub-pixel line of the second sub-pixel circuit 100B. Each overhang structure 110 includes adjacent overhangs 117 and 109. The adjacent overhangs 117 and 109 are defined by a first overhang extension 117A of a second structure 110B extending laterally past an upper surface 105 of a first structure 110A and a second overhang extension 109A of a third structure 110C extending laterally past an upper surface 115 of the second structure 110B. The first structure 110A is disposed over an upper surface 103 of the PS 126B. A first endpoint 120A of a bottom surface 118 of the first structure 110A may extend to or past a first edge 127A of the PS 126B. A second endpoint 120B of the bottom surface of the first structure 110A may extend to or past a second edge 127B of the PS 126B.

[0038] The second structure 110B is disposed over the first structure 110A. The second structure 110B may be disposed on the upper surface 105 of the first structure 110A. The second structure 110B may also be disposed over an intermediate structure. The intermediate structure may be disposed over the upper surface 105 of the first structure 110A. The intermediate structure may be a seed layer or an adhesion layer. The seed layer functions as a current path for the second sub-pixel circuit 100B. The seed layer may include a titanium (Ti) material. The adhesion promotion layer improves adhesion between the first structure 110A and the second structure 110B. The adhesion layer may include a chromium (Cr) material. The third structure 110C is disposed over the second structure 110B. The third structure 110C is disposed over the upper surface 115 of the second structure 110B.

[0039] In one embodiment, the second structure 110B and third structure 110C includes a conductive inorganic material and the first structure 110A of a non- conductive inorganic material. The conductive materials of the second structure 110B and third structure 110C include a copper (Cu), chromium (Cr), aluminum (Al), aluminum neodymium (AINd), molybdenum (Mo), molybdenum tungsten (MoW), or combinations thereof. The non-conductive materials of the first structure 110A include amorphous silicon (a-Si), titanium (Ti), silicon nitride (SisN4), silicon oxide (SiC>2), silicon oxynitride (Si2N2O), or combinations thereof. The overhang structures 110 are able to remain in place, i.e. , are permanent. [0040] Adjacent first overhangs 117 are defined by a first overhang extension 117A. At least a bottom surface 107 of the second structure 110B is wider than the upper surface 105 of a first structure 110A to form the first overhang extension 117A. The first overhang extension 117A of the second structure 11 OB forms the first overhang 117 and allows for the second structure 110B to shadow the first structure

I IOA. The shadowing of the first overhang 117 provides for evaporation deposition of OLED materials 112 and a cathode 114. The OLED materials 112 may include one or more of a HIL, a HTL, an EML, and an ETL. The OLED material is disposed over and in contact with the metal-containing layer 104. The OLED material 112 is disposed under adjacent first overhang 117. The cathode 114 includes a conductive material, such as a metal. E.g., the cathode 114 includes, but is not limited to, silver, magnesium, chromium, titanium, aluminum, ITO, or a combination thereof. The cathode 114 is disposed over the OLED material 112 and a sidewall 123 of the second structure 110B and a sidewall 124 of the third structure 110C of the overhang structures 110.

[0041] Adjacent second overhangs 109 are defined by a second overhang extension 109A of the third structure 110C. At least a bottom surface 121 of the third structure 110C is wider than an upper surface 115 of the second structure 110B to form the second overhang extension 109A of the second overhang 109. The third structure 110C is disposed over the upper surface 115 of the second structure 110B. The second overhang extension 109A of the third structure 110C forms the second overhang 109 and allows for the third structure 110C to shadow the second structure

I I OB. The shadowing of the second overhang 109 provides for evaporation deposition of each of the OLED material 112 and the cathode 114. Each of the OLED material 112 and the cathode 114 are disposed under the second overhang 109. The cathode 114 includes a conductive material, such as a metal. E.g., the cathode 114 includes, but is not limited to, silver, magnesium, chromium, titanium, aluminum, ITO, or a combination thereof. In one embodiment, material of the cathode 114 is different from the material of the first structure 110A, the second structure 110B, and intermediate structure. In some embodiments, e.g., as shown in Figures 1 C as applied to the second sub-pixel circuit 100B, the OLED material 112 and the cathode 114 are disposed over a sidewall 123 of the second structure 110B of the overhang structures 110 in the pixel plane. In other embodiments, the OLED material 112 and the cathode 114 are disposed over an upper surface 115 of the second structure 110B of the overhang structures 110 in the pixel plane. In still other embodiments, the OLED material 112 and the cathode 114 end on the sidewall 111 of the first structure 110A, i.e. , are not disposed over the sidewall 123 of the second structure 110B, the sidewall 124 of the third structure 110C, or the upper surface 122 of the third structure 110C in the pixel plane.

[0042] Each sub-pixel 106 includes an encapsulation layer 116. The encapsulation layer 116 may be or may correspond to a local passivation layer. The encapsulation layer 116 of a respective sub-pixel is disposed over the cathode 114 (and OLED material 112) with the encapsulation layer 116 extending under at least a portion of each of the overhangs 109 and along a sidewall 111 of each of the first structure 110A and the second structure 110B. The encapsulation layer 116 is disposed over the cathode 114 and extends at least to contact the cathode 114 over the sidewall 111 of the first structure 110A in the pixel plane. In some embodiments, the encapsulation layer 116 extends to contact the sidewall 111 of the first structure

I I OA. In the illustrated embodiments as shown in Figures 1 C and 1 D, the encapsulation layer 116 extends to contact the second structure 110B at an underside surface of the first overhang extension 117A and the sidewall 123, contacts the third structure 110C at an underside surface of the second overhang extension 109A, the sidewall 124, and the upper surface 122 of the third structure 110C. In some embodiments, the encapsulation layer 116 extends to contact the third structure 110C at an underside surface of the second overhang extension 109A, the sidewall 124, and the upper surface 122 and is disposed over the OLED material 112 and the cathode 114 when the OLED material 112 and the cathode 114. In some embodiments, the encapsulation layer 116 ends at the sidewall 111 of the first structure 110A, i.e., is not disposed over the sidewall 123 of the second structure

I I OB, the sidewall 124 of the third structure 110C, the upper surface 122 of the third structure 110C, the underside surface of the first overhang extension 117A, or the underside surface of second overhang extension 109A. The encapsulation layer 116 includes the non-conductive inorganic material, such as the silicon-containing material. The silicon-containing material may include SisN4 containing materials.

[0043] Each sub-pixel line may adjacent separation structures, with adjacent subpixels sharing the adjacent separation structures in the line plane. The separation structures are permanent to the second sub-pixel circuit 100B. The separation structures further define each sub-pixel of the sub-pixel line of the second sub-pixel circuit 100B. The separation structures are disposed over an upper surface 103 of the PS 126B.

[0044] The OLED material 112 is disposed over and in contact with the metalcontaining layer 104 and the separation structure in the line plane. The cathode 114 is disposed over the OLED material 112 in the line plane. The encapsulation layer 116 is disposed over the cathode 114 in the line plane. As shown in Figure 1 D, the OLED material 112, the cathode 114, and the encapsulation layer 116 maintain continuity along the length of the line plane in order to apply current across each subpixel 106.

[0045] In embodiments including one or more capping layers, the capping layers are disposed between the cathode 114 and the encapsulation layer 116. E.g., a first capping layer and a second capping layer are disposed between the cathode 114 and the encapsulation layer 116. Each of the embodiments described herein may include one or more capping layers disposed between the cathode 114 and the encapsulation layer 116. The first capping layer may include an organic material. The second capping layer may include an inorganic material, such as lithium fluoride. The first capping layer and the second capping layer may be deposited by evaporation deposition. In another embodiment, the second sub-pixel circuit 100B further includes at least a global passivation layer disposed over the overhang structure 110 and the encapsulation layer 116. In yet another embodiment, the sub-pixel includes an intermediate passivation layer disposed over the overhang structures 110 of each of the sub-pixels 106, and disposed between the encapsulation layer 116 and the global passivation layer.

[0046] Figure 2 is a schematic, cross-sectional view of an overhang structures 210 according to embodiments. The overhang structure 210 is shown without the accompanying substrate 102, metal-containing layer 104, PS 126A/126B, OLED material 112, cathode 114 or encapsulation layer 116. The overhang structure 210 may be disposed over the PS 126A or PS 126B in place of overhang structures 110. [0047] Each overhang structure 210 includes adjacent first overhangs 217, adjacent second overhangs 209, and adjacent third overhangs 222. The adjacent first overhangs 217 are defined by a first overhang extension 217A of a second structure 21 OB extending laterally past an upper surface of the first structure 21 OA. The first structure 21 OA is disposed over an upper surface 103 of the plurality of adjacent PS 126A or PS 126B. The adjacent second overhangs 209 are defined by a second overhang extension 209A of a third structure 21 OC extending laterally past an upper surface of the second structure 21 OB. The third structure 21 OC is disposed over the second structure 21 OB.

[0048] Adjacent third overhangs 222 are defined by a third extension 222A of the fourth structure 21 OD. In one embodiment, the fourth structure 21 OD includes a non- conductive inorganic material. In another embodiment, the fourth structure 21 OD includes a conductive material. At least a bottom surface of the fourth structure 21 OD is wider than an upper surface of the third structure 21 OC to form the third extension 222A of the third overhang 222. The fourth structure 21 OD is disposed over an upper surface of the third structure 21 OC. The third extension 222A of the fourth structure 21 OD forms the third overhang 222 and allows for the fourth structure 21 OD to shadow the third structure 21 OC. The shadowing of the third overhang 222 provides for evaporation deposition of each of the OLED material 112 and the cathode 114. Each of the OLED material 112 and the cathode 114 may be disposed under the third overhang 222.

[0049] Figure 3 is a schematic, cross-sectional view of an overhang structure 310 according to embodiments. The overhang structure 310 is shown without the accompanying substrate 102, metal-containing layer 104, PS 126A/126B, OLED material 112, cathode 114 or encapsulation layer 116. The overhang structure 310 may be disposed over the PS 126A or the PS 126B in place of overhang structures 110.

[0050] Each overhang structure 310 includes adjacent first overhangs 317 and adjacent second overhangs 309. The adjacent first overhangs 317 are defined by a first overhang extension 317A of a second structure 31 OB extending laterally past an upper surface of a first structure 31 OA. The first structure 31 OA is disposed over an upper surface 103 of the plurality of adjacent PS 126A/126B. An intermediate structure 323 is disposed over an upper surface of the second structure 31 OB. In one embodiment, the intermediate structure 323 includes a non-conductive inorganic material. In another embodiment, the intermediate structure 323 includes a conductive material. The adjacent second overhangs 309 are defined by a second overhang extension 309A of a third structure 310C extending laterally past an upper surface of the second structure 31 OB.

[0051] Adjacent second overhangs 309 are defined by a second overhang extension 309A of the third structure 31 OC. At least a bottom surface of the third structure 31 OC is wider than an upper surface of the second structure 31 OB, an upper surface of the intermediate structure 323, and a bottom surface of the intermediate structure 323 to form the second overhang extension 309A of the second overhang 309. The third structure 31 OC is disposed over an upper surface of the intermediate structure 323. The second overhang extension 309A of the third structure 31 OC forms the second overhang 309 and allows for the third structure 31 OC to shadow the second structure 31 OB and the intermediate structure 323.

[0052] Figure 4 is a schematic, cross-sectional view of an overhang structure 410 according to embodiments. The overhang structure 410 is shown without the accompanying substrate 102, metal-containing layer 104, PS 126A/126B, OLED material 112, cathode 114 or encapsulation layer 116. The overhang structure 410 may be disposed over the PS 126A or the PS 126B in place of overhang structures 110.

[0053] Each overhang structure 410 includes adjacent first overhangs 417 and adjacent second overhangs 409. The adjacent first overhangs 417 are defined by a first overhang extension 417A of a second structure 410B extending laterally past an upper surface of a first structure 410A. The first structure 41 OA is disposed over an upper surface 103 of the plurality of adjacent PS 126A/126B.

[0054] Adjacent second overhangs 409 are defined by a sidewall 413 of the third structure 41 OC. At least an upper surface of the third structure 41 OC is wider than a bottom surface of the third structure 41 OC to form the sidewall 413 of the second overhang 409. The sidewall 413 of the third structure 41 OC forms the second overhang 409. [0055] Figure 5 is a schematic, cross-sectional view of an overhang structure 510 according to embodiments. The overhang structure 510 is shown without the accompanying substrate 102, metal-containing layer 104, PS 126A/126B, OLED material 112, cathode 114 or encapsulation layer 116. The overhang structure 510 may be disposed over the PS 126A or the PS 126B in place of overhang structures 110.

[0056] Each overhang structure 510 includes adjacent first overhangs 517, adjacent second overhangs 509, and adjacent third overhangs 522. The adjacent first overhangs 517 are defined by a first overhang extension 517A of a second structure 510B extending laterally past an upper surface of a first structure 510A. The first structure 510A is disposed over an upper surface 103 of the plurality of adjacent PS 126A/126B.

[0057] Adjacent second overhangs 509 are defined by a sidewall 513 of the third structure 510C. At least an upper surface of the third structure 510C is wider than a bottom surface of the third structure 510C to form sidewall 513 of the second overhang 509. The sidewall 513 of the third structure 510C forms the second overhang 509.

[0058] Adjacent third overhangs 522 are defined by a sidewall 515 of the fourth structure 510D. At least a bottom surface of the fourth structure 510D is wider than a bottom surface of the fourth structure 510D to form the sidewall 515 of the third overhang 522. The fourth structure 510D is disposed over an upper surface of the third structure 510C. The sidewall 515 of the fourth structure 510D forms the third overhang 522.

[0059] Figure 6 is a schematic, cross-sectional view of an overhang structure 610 according to embodiments. The overhang structure 610 is shown without the accompanying substrate 102, metal-containing layer 104, PS 126A/126B, OLED material 112, cathode 114 or encapsulation layer 116. The overhang structure 610 may be disposed over the PS 126A or PS 126B in place of overhang structures 110.

[0060] Each overhang structure 610 includes adjacent first overhangs 617 and adjacent second overhangs 609. The adjacent first overhangs 617 are defined by a first overhang extension 617A of a second structure 610B extending laterally past an upper surface 103 of a first structure 610A. The first structure 61 OA is disposed over the upper surface 103 of the plurality of adjacent PS 126A/126B.

[0061] The second structure 61 OB includes a lower sidewall 623 and an upper sidewall 624. Adjacent second overhangs 609 are defined by the upper sidewall 624 of the second structure 61 OB. An upper surface 615 of the second structure 61 OB may be wider than, equal to (as shown in the illustrated embodiment), or narrower than the bottom surface 607 of the second structure 61 OB. The second structure 61 OB further comprises an interior plane 625. The upper surface 615 and the bottom surface 607 of the second structure 61 OB are wider than the second structure 61 OB at the interior plane 625. The lower sidewall 623 is formed between the bottom surface 607 and the interior plane 625 of the second structure 61 OB. The upper sidewall 624 is formed between the upper surface 615 and the interior plane 625 of the second structure 610B. The upper sidewall 613 of the second structure 610B forms the second overhang 609 and allows for the upper sidewall 613 to shadow the sidewall 623.

[0062] The encapsulation layer 116 is disposed under the adjacent overhangs of overhang structures 110, 210, 310, 410, 510, and 610. The adjacent overhangs thus provide protection against moisture invasion of the overhang structures 110, 210, 310, 410, 510, and 610. The adjacent overhangs create a more complex invasion path for moisture due to the contact between the encapsulation layer 116 and the overhang structures 110, 210, 310, 410, 510, and 610. As moistures invades the overhang structures 110, 210, 310, 410, 510, and 610, the encapsulation layer 116 creates a barrier between the moisture and the overhang structures 110, 210, 310, 410, 510, and 610.

[0063] Figure 7 is a flow diagram of a method 700 for forming a first sub-pixel circuit 100A or a second sub-pixel circuit 100B. Figures 8A-8D are schematic, cross- sectional views of a substrate 102 during the method 700 for forming the first subpixel circuit 100A or second sub-pixel circuit 100B.

[0064] At operation 701 , as shown in Figure 8A, a first structure layer 802A and a second structure layer 802B are deposited over the substrate 102. The first structure layer 802A is disposed over the PS 126A or PS 126B. The second structure layer 802B is disposed over the first structure layer 802A. The first structure layer 802A corresponds to the first structure 1 10A, 21 OA, 31 OA, 41 OA, 51 OA, and 61 OA of the overhang structures 1 10, 210, 310, 410, 510, and 610, respectively. The second structure layer 802B corresponds to the second structure 1 1 OB, 21 OB, 31 OB, 41 OB, 51 OB, and 61 OB of the overhang structures 1 10, 210, 310, 410, 510, and 610. The second structure layer 802B may also correspond to the third structure 1 10C, 21 OC, 31 OC, 41 OC, and 51 OC, the intermediate structure 323, and the fourth structure 21 OD and 51 OD. A resist 806 is disposed and patterned. The resist 806 is disposed over the second structure layer 802B. The resist 806 is a positive resist or a negative resist. A positive resist includes portions of the resist, which, when exposed to electromagnetic radiation, are respectively soluble to a resist developer applied to the resist after the pattern is written into the resist using the electromagnetic radiation. A negative resist includes portions of the resist, which, when exposed to radiation, will be respectively insoluble to the resist developer applied to the resist after the pattern is written into the resist using the electromagnetic radiation. The chemical composition of the resist 306 determines whether the resist is a positive resist or a negative resist.

[0065] At operation 702, as shown in Figure 8B, portions of the second structure layer 802B exposed by the resist 806 are removed. The second structure layer 802B exposed by the resist 806 may be removed by a dry etch process. In the illustrated embodiment, the operation 702 forms the second structure 1 1 OB and the third structure 1 10C. In other embodiments, the operation 702 may form the second structure 21 OB, 31 OB, 41 OB, 51 OB, and 61 OB, the third structure 21 OC, 31 OC, 41 OC, and 51 OC, the intermediate structure 323, and the fourth structure 21 OD and 51 OD.

[0066] At operation 703, as shown in Figure 8C, portions of the first structure layer 802A exposed by the resist 806 are removed. The first structure layer 802A exposed by the resist 806 may be removed by a wet etch process. In the illustrated embodiment, the operation 703 forms the first structure 1 10A of the overhang structures 110. In other embodiments, the operation 703 forms the first structure 21 OA, 31 OA, 41 OA, 51 OA, and 61 OA of the overhang structures 110, 210, 310, 410, 510, and 610, respectively. The etch selectivity between the materials of the second structure layer 802B corresponding to the second structure 1 1 OB and third structure 1 10C, the first structure layer 802A corresponding to the first structure 1 10A, and the etch processes to remove the exposed portions of the second structure layer 802B and the first structure layer 802A provide for the bottom surface 107 of the second structure 110B being wider than the upper surface 105 of the first structure 110A to form a first overhang extension 117A of the first overhang 117.

[0067] At operation 704, as shown in Figure 8D, the resist 806 is removed from the third structure 110C, leaving behind the overhang structures 110.

[0068] At operation 705, the OLED material 112 of the first sub-pixel 108A, the cathode 114, and the encapsulation layer 116 are deposited. The shadowing of the first overhang 117 and the second overhang 109 provides for evaporation deposition of each of the OLED material 112 and a cathode 114.

[0069] In summation, described herein relate to sub-pixel circuits and methods of forming sub-pixel circuits that may be utilized in a display such as an organic lightemitting diode (OLED) display. A plurality of adjacent pixel (PS) disposed over the substrate. Each sub-pixel includes adjacent first overhangs, each first overhang defined by a first overhang extension of a second structure extending laterally past an upper surface of a first structure. The first structure is disposed over the PS while the second structure is disposed over the first structure. Adjacent second overhangs are defined by a second overhang extension of a third structure extending laterally past an upper surface of the second structure. The third structure is disposed over the second structure. An encapsulation layer is disposed in the adjacent second overhang, providing protection against the invasion of moisture into the adjacent first overhangs to improve the functionality of the sub-pixel circuit.

[0070] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

What is claimed is:

1. A device, comprising: a substrate; a plurality of overhang structures disposed over the substrate, each overhang structure having: a first structure; a second structure disposed over an upper surface of the first structure; adjacent first overhangs, each first overhang defined by a first overhang extension of the second structure extending laterally past an upper surface of the first structure; a third structure, wherein the third structure disposed over the second structure; and adjacent second overhangs; and a plurality of sub-pixels, each sub-pixel comprising: an anode; an organic light emitting diode (OLED) material disposed over the anode; and a cathode disposed over the OLED material.

2. The device of claim 1 , wherein the adjacent second overhangs are defined by a second overhang extension of the third structure extending laterally past an upper surface of the second structure, and wherein the third structure is disposed over the upper surface of the second structure.

3. The device of claim 1 , wherein the third structure further comprises: a bottom surface; and an upper surface, wherein the upper surface is wider than the bottom surface; and a sidewall formed between the bottom surface and the upper surface, wherein the adjacent second overhangs are defined by the sidewall.

4. The device of claim 3, further comprising: a fourth structure disposed over the upper surface of the third structure, comprising: a bottom surface; and an upper surface, wherein the upper surface is wider than the bottom surface; and a sidewall formed between the bottom surface and the upper surface; and an adjacent third overhang, wherein the adjacent third overhang is defined by the sidewall.

5. The device of claim 1 , further comprising: adjacent third overhangs, each third overhang defined by a third extension of a fourth structure extending laterally past an upper surface of the third structure, wherein the fourth structure disposed over the upper surface of the third structure.

6. The device of claim 1 , further comprising an intermediate structure disposed over the second structure, wherein the third structure is disposed over the intermediate structure.

7. The device of claim 1 , further comprising: a fourth structure disposed over the upper surface of the third structure, comprising: a bottom surface; and an upper surface, wherein the upper surface is wider than the bottom surface; and a sidewall formed between the bottom surface and the upper surface; and an adjacent third overhang, wherein the adjacent third overhang is defined by the sidewall.

8. The device of claim 1 , further comprising pixel structures (PS) disposed over the substrate, and wherein the overhang structures are disposed over the PS.

9. The device of claim 7, wherein the PS comprise polyimides, silicon oxide

(SiC>2), silicon nitride (SisN4), silicon oxynitride (Si₂N₂O), magnesium fluoride (MgF2), or combinations thereof.

10. The device of claim 1 , further comprising a pixel structure (PS) disposed over the substrate, and wherein the overhang structures are disposed over the PS.

11. The device of claim 9, wherein the PS comprises polyimides, silicon oxide (SiC>2), silicon nitride (SisN4), silicon oxynitride (Si₂N₂O), magnesium fluoride (MgF2), or combinations thereof.

12. A device, comprising: a substrate; a plurality of overhang structures disposed over the substrate, each overhang structure having: a first structure; a second structure disposed over an upper surface of the first structure, the second structure comprising: an interior plane; an upper surface; an upper sidewall formed between the interior plane and the upper surface; a bottom surface; and a lower sidewall formed between the interior plane and the bottom surface; adjacent first overhangs, each first overhang defined by a first overhang extension of the second structure extending laterally past an upper surface of the first structure; and adjacent second overhangs formed by the upper sidewall; and a plurality of sub-pixels, each sub-pixel comprising: an anode; an organic light emitting diode (OLED) material disposed over the anode; and a cathode disposed over the OLED material.

13. The device of claim 12, wherein the upper sidewall is wider than the second structure at the interior plane.

14. The device of claim 12, further comprising pixel structures (PS) disposed over the substrate, and wherein the overhang structures are disposed over the PS.

15. The device of claim 14, wherein the pixel structures (PS) comprise polyimides, silicon oxide (SiC>2), silicon nitride (SisN4), silicon oxynitride (Si₂N₂O), magnesium fluoride (MgF2), or combinations thereof.

16. The device of claim 12, further comprising a pixel structure (PS) disposed over the substrate, and wherein the overhang structures are disposed over the PS.

17. The device of claim 15, wherein the PS comprises polyimides, silicon oxide (SiC>2), silicon nitride (SisN4), silicon oxynitride (Si₂N₂O), magnesium fluoride (MgF2), or combinations thereof.

18. A method, comprising: depositing a first structure layer and a second structure layer over a substrate; removing portions of the second structure layer exposed by a resist to form a second structure and a third structure; removing portions of the first structure layer exposed by the resist to form a first structure; removing the resist from the third structure; and depositing an organic light emitting diode (OLED) material, a cathode, and an encapsulation layer.

19. The method of claim 18, wherein the portions of the second structure layer are removed by a dry etch process.

20. The method of claim 18, wherein the portions of the first structure layer are removed by a wet etch process.