DESCENDING ETCHING RESISTANCE IN ADVANCED SUBSTRATE PATTERNING

Sub-pixel circuits and methods of forming sub-pixel circuits that may be utilized in a display such as an organic light-emitting diode (OLED) display. In one example, a device includes a substrate, pixel-defining layer (PDL) structures disposed over the substrate and defining sub-pixels of the device, and a plurality of overhang structures. The first sub-pixel includes a first anode, OLED material, a first cathode, and a first encapsulation layer having a gap defined by a first portion of the first encapsulation layer disposed over the first cathode, a second portion of the first encapsulation layer disposed over a sidewall of the body structure, and a third portion of the first encapsulation layer under an underside surface of the top extension of the top structure, the first portion of the first encapsulation layer contacting the third portion of the first encapsulation layer.

BACKGROUND

Field

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 light-emitting diode (OLED) display.

Description of the Related Art

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 semi-transparent 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.

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, photolithography 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 that may be utilized in a display such as an organic OLED display.

SUMMARY

[In one embodiment, a device is provided. The device includes a substrate, pixel-defining layer (PDL) structures disposed over the substrate and defining sub-pixels of the device, and a plurality of overhang structures. Each overhang structure is defined by a top extension of a top structure extending laterally past a body structure, each body structure is disposed over an upper surface of each PDL structure, adjacent overhang structures of the plurality overhang structures define a plurality of sub-pixels including a first sub-pixel. The first sub-pixel includes a first anode, a first organic light-emitting diode (OLED) material disposed over the first anode and under the adjacent overhang structures, a first cathode disposed over the first OLED material and under the adjacent overhang structures, and a first encapsulation layer having a gap defined by a first portion of the first encapsulation layer disposed over the first cathode, a second portion of the first encapsulation layer disposed over a sidewall of the body structure, and a third portion of the first encapsulation layer under an underside surface of the top extension of the top structure, the first portion of the first encapsulation layer contacting the third portion of the first encapsulation layer.

In another embodiment, a device is provided. The device includes a substrate, pixel-defining layer (PDL) structures disposed over the substrate and defining sub-pixels of the device, and a plurality of overhang structures. Each overhang structure is defined by a top extension of a top structure extending laterally past a body structure to form an overhang, each body structure is disposed over an upper surface of each PDL structure, adjacent overhang structures of the plurality overhang structures define a plurality of sub-pixels including a first sub-pixel and a second sub-pixel. the first sub-pixel includes a first anode, a first organic light-emitting diode (OLED) material disposed over the first anode and under the adjacent overhang structures, a first cathode disposed over the first OLED material and under the adjacent overhang structures, and a first encapsulation layer having a gap defined by a first portion of the first encapsulation layer disposed over the first cathode, a second portion of the first encapsulation layer disposed over a sidewall of the body structure, and a third portion of the first encapsulation layer under an underside surface of the top extension of the top structure, the first portion of the first encapsulation layer contacting the third portion of the first encapsulation layer. The second sub-pixel includes a second anode, a second organic light-emitting diode (OLED) material disposed over the second anode and under the adjacent overhang structures, a second cathode disposed over the second OLED material and under the adjacent overhang structures, and a second encapsulation layer having the gap defined by the first portion of the second encapsulation layer disposed over the second cathode, the second portion of the second encapsulation layer disposed over the sidewall of the body structure, and the third portion of the second encapsulation layer under the underside surface of the top extension of the top structure, the first portion of the second encapsulation layer contacting the third portion of the second encapsulation layer.

In another embodiment, a device is provided. The device includes a substrate, pixel-defining layer (PDL) structures disposed over the substrate and defining sub-pixels of the device, and a plurality of overhang structures. Each overhang structure is defined by a top extension of a top structure extending laterally past a body structure, each body structure is disposed over an upper surface of each PDL structure, adjacent overhang structures of the plurality overhang structures define a plurality of sub-pixels including a first sub-pixel. The first sub-pixel includes a first anode, a first organic light-emitting diode (OLED) material disposed over and in contact with the first anode and under the adjacent overhang structures, a first cathode disposed over the first OLED material and under the adjacent overhang structures, and a first encapsulation layer having a gap defined by a first portion of the first encapsulation layer contacting the first cathode, a second portion of the first encapsulation layer contacting a sidewall of the body structure, and a third portion of the first encapsulation layer contacting an underside surface of the top extension of the top structure, the first portion of the first encapsulation layer contacting the third portion of the first encapsulation layer.

DETAILED DESCRIPTION

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 light-emitting diode (OLED) display.

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 three 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 three or more sub-pixels. Each sub-pixel has the OLED material configured to emit a white, red, green, blue or other color light when energized. E.g., the OLED material of a first sub-pixel emits a red light when energized, the OLED material of a second sub-pixel emits a green light when energized, and the OLED material of a third sub-pixel emits a blue light when energized.

The overhang structures are permanent to the sub-pixel circuit and include at least a top structure disposed over a body 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 one embodiment, the HIL layer has a greater conductivity than the HTL layer. In another embodiment, the HIL layer has a greater energy level than the HTL layer. 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 overhang structures and the evaporation angle set by the evaporation source define the deposition angles, i.e., the overhang structures provide for a shadowing effect during evaporation deposition with the evaporation angle set by the evaporation source. In order to deposit at a particular angle, the evaporation source is configured to emit the deposition material at a particular angle with regard to the overhang structure. The encapsulation layer of a respective sub-pixel is disposed over the cathode with the encapsulation layer extending under at least a portion of each of the adjacent overhang structures. The encapsulation layer of each sub-pixel contacts at least a portion of a sidewall of each of the adjacent overhang structures. The encapsulation layer can be varied by thickness, composition, and deposition method depending on the OLED materials deposited on the sub-pixels.

FIG.1Ais a schematic, cross-sectional view of a sub-pixel circuit100having an arrangement101A. The cross-sectional view ofFIG.1Ais taken along section line1′-1′ ofFIGS.1C and1D.FIG.1Bis a schematic, cross-sectional view of a sub-pixel circuit100having arrangement101B. The cross-sectional view ofFIG.1Bis taken along section line1′-1′ ofFIGS.1C and1D.

The sub-pixel circuit100includes a substrate102. Metal-containing layers104may be patterned on the substrate102and are defined by adjacent pixel-defining layer (PDL) structures126disposed on the substrate102. In one embodiment, the metal-containing layers104are pre-patterned on the substrate102. E.g., the substrate102is a pre-patterned indium tin oxide (ITO) glass substrate. The metal-containing layers104are configured to operate anodes of respective sub-pixels. The metal-containing layers104include, but are not limited to, chromium, titanium, gold, silver, copper, aluminum, ITO, a combination thereof, or other suitably conductive materials.

The PDL structures126are disposed on the substrate102. The PDL structures126include one of an organic material, an organic material with an inorganic coating disposed thereover, or an inorganic material. The organic material of the PDL structures126includes, but is not limited to, polyimides. The inorganic material of the PDL structures126includes, but is not limited to, silicon oxide (SiO2), silicon nitride (Si3N4), silicon oxynitride (Si2N2O), magnesium fluoride (MgF2), or combinations thereof. Adjacent PDL structures126define a respective sub-pixel and expose the anode (i.e., metal-containing layer104) of the respective sub-pixel of the sub-pixel circuit100.

The sub-pixel circuit100has a plurality of sub-pixels106including at least a first sub-pixel108a, a second sub-pixel108b, and a third sub-pixel108c. While the Figures depict the first sub-pixel108a, the second sub-pixel108b, and the third sub-pixel108c, the sub-pixel circuit100of the embodiments described herein may include three or more sub-pixels106, such as a fourth and a fifth sub-pixel. Each sub-pixel106has an organic light-emitting diode (OLED) material112configured to emit a white, red, green, blue or other color light when energized. E.g., the OLED material112of the first sub-pixel108aemits a red light when energized, the OLED material of the second sub-pixel108bemits a green light when energized, the OLED material of a third sub-pixel108cemits a blue light when energized, and the OLED material of a fourth sub-pixel and a fifth sub-pixel emits another color light when energized.

Overhang structures110are disposed on an upper surface103of each of the PDL structures126. The overhang structures110are permanent to the sub-pixel circuit. The overhang structures110further define each sub-pixel106of the sub-pixel circuit100. The overhang structures110include at least a top structure1106disposed over a body structure110A. In one embodiment, the top structure1106is disposed on the body structure110A. The body structure110A is disposed over the upper surface103of the PDL structure126. In one embodiment, the body structure110A is disposed on the upper surface103of the PDL structure126. Each overhang structure110includes adjacent overhangs109. The adjacent overhangs109are defined by a top extension109A of the top structure1106extending laterally past a sidewall111of the body structure110A.

The top structure1106includes one of a non-conductive material, inorganic material, or metal-containing material. The body structure110A includes an non-conductive material, inorganic material, or metal-containing material. The non-conductive material includes, but it not limited to, an inorganic silicon-containing material. E.g., the silicon-containing material includes oxides or nitrides of silicon, or combinations thereof. The metal-containing materials include at least one of a metal or metal alloy such as titanium (Ti), aluminum (Al), aluminum neodymium (AlNd), molybdenum (Mo), molybdenum tungsten (MoW), copper (Cu), or combinations thereof. The inorganic materials of the body structure110A and the top structure110B include silicon nitride (Si3N4), silicon oxide (SiO2), silicon oxynitride (Si2N2O), or combinations thereof. The overhang structures110are able to remain in place, i.e., are permanent. Thus, organic material from lifted off overhang structures that disrupt OLED performance would not be left behind. Eliminating the need for a lift-off procedure also increases throughput.

In one example, the top structure110B includes a non-conductive inorganic material and the body structure110A includes a conductive inorganic material or a metal-containing material. In another example, the top structure110B includes a conductive inorganic material or metal-containing material and the body structure110A includes a conductive inorganic material or metal-containing material.

Adjacent overhangs109are defined by the top extension109A of the top structure110B. At least a bottom surface107of the top structure110B is wider than a top surface105of the body structure110A to form the top extension109A (as shown inFIGS.1A and1B) of the overhang109. The top structure110B is disposed over a top surface105of the body structure110A. The top extension109A of the top structure110B forms the overhang109and allows for the top structure110B to shadow the body structure110A. The shadowing of the overhang109provides for evaporation deposition of each of the OLED material112and a cathode114. The OLED material112is disposed under the overhang109. The cathode114is disposed over the OLED material112and extends under the overhang109. In one embodiment, as shown inFIGS.2A and2B, the cathode114contacts a first portion220of the sidewall111of the body structure110A.

The overhang structures110and an evaporation angle set by an evaporation source define deposition angles, i.e., the overhang structures110provide for a shadowing effect during evaporation deposition with the evaporation angle set by the evaporation source. The overhang109and the evaporation source define an OLED angle θOLEDof the OLED material112and a cathode angle θcathodeof the cathode114(shown inFIG.2A). The OLED angle θOLEDof the OLED material112and the cathode angle θcathodeof the cathode114result from the overhang structures110and the evaporation angle set by the evaporation source, i.e., the overhang structures110provide for a shadowing effect during evaporation deposition of the OLED material112and the cathode114with the evaporation angle set by the evaporation source. In one embodiment, the OLED material112and the cathode114contact the sidewall111of the body structure110A of the overhang structures110. In another embodiment, as shown inFIG.1A, the cathode114contacts the sidewall111of the body structure110A of the overhang structures110. In one embodiment, as shown inFIG.1A, the encapsulation layer116is disposed over the sidewall111of the body structure110A and a bottom surface107of the top structure110B. In another embodiment, the cathode114contacts busbars (not shown) outside of an active area of the sub-pixel circuit100. The cathode114includes a conductive material, such as a metal or metal alloy. E.g., the cathode114includes, but are not limited to, chromium, titanium, aluminum, ITO, or a combination thereof. In some embodiments, the material of the cathode114is different from the material of the body structure110A and the top structure110B.

Each sub-pixel106includes an encapsulation layer116, e.g., the first sub-pixel108ahas a first encapsulation layer116A, the second sub-pixel108bhas a second encapsulation layer116B, and the third sub-pixel108chas a third encapsulation layer116C. The encapsulation layer116may be or may correspond to a local passivation layer. The encapsulation layer116of a respective sub-pixel is disposed over the cathode114(and OLED material112) with the encapsulation layer116extending under at least a portion of the overhang structures110and over at least a portion of a sidewall of each of the adjacent overhang structures110. In one embodiment, as shown in sub-pixels108band108cofFIG.1A, the second encapsulation layer116B and third encapsulation layer116C are disposed over the cathode114and extends under the adjacent overhangs109to contact a second portion (not shown) the sidewall111of the body structure110A. In another embodiment, as shown in sub-pixel108aofFIG.1A, the first encapsulation layer116A is disposed over the sidewall111of the body structure110A and a bottom surface107of the top structure110B.

In another embodiment, as shown in sub-pixel108aofFIG.1B, the first encapsulation layer116A is disposed over the sidewall111of the body structure110A, the bottom surface107of the top structure110B, a sidewall113of the top structure110B, and a portion of a top surface115of the top structure110B of the overhang structures110. The first encapsulation layer116A has gaps150. Each of the gaps150is defined by a first portion151, a second portion152, a third portion153, and the first portion151contacting the third portion153of the first encapsulation layer116A. The first portion151of the first encapsulation layer116A is disposed over the cathode114. In some embodiments, the first portion151contacts the cathode114. The second portion152of the first encapsulation layer116A is disposed over the sidewall111of the body structure110A. In some embodiments, the second portion152contacts the sidewall111of the body structure110A. The third portion153of the first encapsulation layer116A is disposed under an underside surface117of the top extension109A of the top structure110B. In some embodiments, the third portion153contacts the underside surface117of the top extension109A of the top structure110B. The first portion151of the first encapsulation layer116A contacts the third portion153of the first encapsulation layer116A. The gaps150are sealed by the contact of the first portion151and the third portion153. The first encapsulation layer116A has an inner surface155and an outer surface156. The inner surface155contacts the cathode114, the sidewall111of the body structure110A, and the underside surface117of the top extension109A of the top surface110B. The outer surface156encloses void spaces outside the first encapsulation layer116A. The void spaces correspond to the gaps150. In one or more embodiments, the gaps150and the voids have a size less than the height of the overhang109. In one or more embodiments, the gaps150and the voids have a size less than 1.5 μm, such as less than 0.5 μm.

In some embodiments, as shown in second sub-pixel108bofFIG.1B, the second encapsulation layer116B is disposed over the sidewall111of the body structure110A, the bottom surface107of the top structure110B, the sidewall113of the top structure110B, and the portion of the top surface115of the top structure110B of the overhang structures110. The second encapsulation layer116B has the gaps150. Each of the gaps150is defined by the first portion151, the second portion152, the third portion153, and the first portion151contacting the third portion153of the second encapsulation layer116B. The first portion151of the second encapsulation layer116B is disposed over the cathode114. In some embodiments, the first portion151contacts the cathode114. The second portion152of the second encapsulation layer116B is disposed over the sidewall111of the body structure110A. In some embodiments, the second portion152contacts the sidewall111of the body structure110A. The third portion153of the second encapsulation layer116B is disposed under the underside surface117of the top extension109A of the top structure110B. In some embodiments, the third portion153contacts the underside surface117of the top extension109A of the top structure110B. The first portion151of the second encapsulation layer116B contacts the third portion153of the second encapsulation layer116B. The gaps150are sealed by the contact of the first portion151and the third portion153. The second encapsulation layer116B has the inner surface155and the outer surface156. The inner surface155contacts the cathode114, the sidewall111of the body structure110A, and the underside surface117of the top extension109A of the top surface110B. The outer surface156encloses the void spaces outside the second encapsulation layer116B. The void spaces correspond to the gaps150.

In some embodiments, the portion of the top surface115of the top structure110B that the first encapsulation layer116A is disposed over is separated from the portion of the top surface115of the top structure110B that the second encapsulation layer116B is disposed over. A space160therefore exists between the first encapsulation layer116A and the second encapsulation layer116B, as shown inFIG.1B. In some embodiments, the first encapsulation layer116A overlaps with the second encapsulation layer116B.

In some embodiments, as shown in third sub-pixel108cofFIG.1B, the third encapsulation layer116C is disposed over the sidewall111of the body structure110A, the bottom surface107of the top structure110B, the sidewall113of the top structure110B, and the portion of the top surface115of the top structure110B of the overhang structures110. The third encapsulation layer116C has the gaps150. Each of the gaps150is defined by the first portion151, the second portion152, the third portion153, and the first portion151contacting the third portion153of the third encapsulation layer116C. The first portion151of the third encapsulation layer116C is disposed over the cathode114. In some embodiments, the first portion151contacts the cathode114. The second portion152of the third encapsulation layer116C is disposed over the sidewall111of the body structure110A. In some embodiments, the second portion152contacts the sidewall111of the body structure110A. The third portion153of the third encapsulation layer116C is disposed under the underside surface117of the top extension109A of the top structure110B. In some embodiments, the third portion153contacts the underside surface117of the top extension109A of the top structure110B. The first portion151of the third encapsulation layer116C contacts the third portion153of the third encapsulation layer116C. The gaps150are sealed by the contact of the first portion151and the third portion153. The third encapsulation layer116C has the inner surface155and the outer surface156. The inner surface155contacts the cathode114, the sidewall111of the body structure110A, and the underside surface117of the top extension109A of the top surface110B. The outer surface156encloses the void spaces outside the third encapsulation layer116C. The void spaces correspond to the gaps150.

In some embodiments, the portion of the top surface115of the top structure110B that the second encapsulation layer116B is disposed over is separated from the portion of the top surface115of the top structure110B that the third encapsulation layer116C is disposed over. The space160therefore exists between the second encapsulation layer116B and the third encapsulation layer116C. In some embodiments, the second encapsulation layer116B overlaps with the third encapsulation layer116C, as shown inFIG.1B.

In embodiments including one or more capping layers, the capping layers are disposed between the cathode114and the encapsulation layer116. E.g., a first capping layer and a second capping layer are disposed between the cathode114and the encapsulation layer116. Each of the embodiments described herein may include one or more capping layers disposed between the cathode114and the encapsulation layer116. 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 sub-pixel circuit100further includes at least a global passivation layer120disposed over the overhang structure110and the encapsulation layer116. In yet another embodiment, the sub-pixel includes an intermediate passivation layer disposed over the overhang structures110of each of the sub-pixels106, and disposed between the encapsulation layer116and the global passivation layer120.

The arrangement101A and the arrangement101B of the sub-pixel circuit100further include at least a global passivation layer120disposed over the overhang structures110and the encapsulation layers116. In one embodiment, an intermediate layer118may be disposed between the global passivation layer120and the overhang structures110and the encapsulation layers116. The intermediate layer118may include an inkjet material, such as an acrylic material.

FIG.1Cis a schematic, top sectional view of a sub-pixel circuit100having a dot-type architecture101C.FIG.1Dis a schematic, cross-sectional view of a sub-pixel circuit100having a line-type architecture101D. Each of the top sectional views ofFIGS.1C and1Dare taken along section line1′-1′ ofFIGS.1A and1B. The dot-type architecture101C includes a plurality of pixel openings124A from adjacent PDL structures126. Each of pixel opening124A is surrounded by overhang structures110, as shown inFIG.1A, that defines each of the sub-pixels106of the dot-type architecture101C. The line-type architecture101D includes a plurality of pixel openings124B from adjacent PDL structures126. Each of pixel opening124B is abutted by overhang structures110, as shown inFIG.1A, that define each of the sub-pixels106of the line-type architecture101D.

FIG.2Ais a schematic, cross-sectional view of an overhang structure110of a sub-pixel circuit100.FIG.2Bis a schematic, cross-sectional view of an overhang structure110of a sub-pixel circuit100. In one embodiment, the overhang structures110include a top structure110B of a non-conductive inorganic material and a body structure110A of a conductive inorganic material. In another embodiment, the overhang structures110including the top structure110B of a conductive inorganic material and the body structure110A of a conductive inorganic material. In one embodiment, the cathode114contacts the body structure110A of the overhang structures110. In another embodiment, as shown inFIG.2B, the encapsulation layer116has the gaps150. Each of the gaps150is defined by the first portion151, the second portion152, the third portion153, and the first portion151contacting the third portion153of the encapsulation layer116. The first portion151of the encapsulation layer116is disposed over the cathode114. In some embodiments, the first portion151contacts the cathode114. The second portion152of the encapsulation layer116is disposed over the sidewall111of the body structure110A. In some embodiments, the second portion152contacts the sidewall111of the body structure110A. The third portion153of the encapsulation layer116disposed under the underside surface117of the top extension109A of the top structure1106. In some embodiments, the third portion153contacts the underside surface117of the top extension109A of the top structure1106. The first portion151of the encapsulation layer116contacts the third portion153of the encapsulation layer116. The gaps150are sealed by the contact of the first portion151and the third portion153.

The top structure1106includes an underside edge206and an overhang vector208. The underside edge206extends past the sidewall111of the body structure110A. The overhang vector208is defined by the underside edge206and the PDL structure126. The OLED material112is disposed over the metal-containing layer104, over the sidewall127of the PDL structure126, and over a first portion210of the upper surface103of the PDL structure126, extending under the overhang109to an OLED endpoint218. The OLED material112forms an OLED angle θOLEDbetween an OLED vector212and the overhang vector208. The OLED vector212is defined by an OLED endpoint218extending under the top structure1106and the underside edge206of the top structure1106. In one embodiment, the OLED material112may include one or more of a HIL, a HTL, an EML, and an ETL.

The cathode114is disposed over the OLED material112, over the first portion210of the PDL structure126, and over a second portion211of the upper surface103of the PDL structures126in each sub-pixel106. In some embodiments, which can be combined with other embodiments described herein, the cathode114is disposed on a first portion220of the sidewall111of the body structure110A. In other embodiments, as shown inFIG.2A, the cathode114forms a cathode angle θcathodebetween a cathode vector224and the overhang vector208. The cathode vector224is defined by a cathode endpoint226extending under the top structure1106and the underside edge206of the top structure1106.

The encapsulation layer116is disposed over the cathode114(and OLED material112) with the encapsulation layer116extending at least under the top structure110B of the overhang structure110and over at least a portion of a sidewall of the overhang structure110. In one embodiment, as shown in sub-pixels108a,108b, and108cofFIG.1A, the second encapsulation layer116B and the third encapsulation layer116C are disposed over the cathode114and extends under the adjacent overhangs109to contact a second portion (not shown) of the sidewall111of the body structure110A. In another embodiment, as shown inFIG.2A, the first encapsulation layer116A is disposed over the sidewall111of the body structure110A and a bottom surface107of the top structure110B. In another embodiment, as shown inFIG.2B, the first encapsulation layer116A contacts the sidewall111of the body structure110A, the bottom surface107of the top structure110B, a sidewall113of the top structure110B, and a portion of a top surface115of the top structure110B of the overhang structures110. The encapsulation layer116further includes a top surface119that defines the uppermost edge of the encapsulation layer116between the sidewalls111of the body structure110A.

In one embodiment, as shown inFIG.1A, the encapsulation layer116may be varied using deposition thicknesses. Each encapsulation layer116has a thickness. The thickness is the distance from the bottom surface of the encapsulation layer to the top surface of the encapsulation layer116. The first encapsulation layer116A has a first thickness t1, the second encapsulation layer116B has a second thickness t2, and the third encapsulation layer116C has a third thickness t3. In another embodiment, the second thickness t2is different from the first thickness t1, and the third thickness t3that is different from the first thickness t1and the second thickness t2. In one embodiment, as shown inFIG.1A, the thickness t1is greater than the thicknesses t2and t3, and thickness t2is greater than thickness t3.

In another embodiment, the thickness of the encapsulation layer116is increased as the wavelength of the light emitted increases, e.g., the first encapsulation layer116A thickness t1is thickest at sub-pixel108ahaving a red OLED material112(˜580 nm), the second encapsulation layer116B thickness t2is thinner at second sub-pixel108bhaving a green OLED material112(˜540 nm), and the third encapsulation layer116C thickness t3is thinnest at sub-pixel108chaving a blue OLED material112(˜440 nm). In another embodiment, the thickness of the encapsulation layer116is decreased as the wavelength of light emitted increases, e.g. the first encapsulation layer116A thickness t1is thinnest at sub-pixel108ahaving a red OLED material112(˜580 nm), the second encapsulation layer116B thickness t2is thicker at second sub-pixel108bhaving a green OLED material112(˜540 nm), and the third encapsulation layer116C thickness t3is thickest at sub-pixel108chaving a blue OLED material112(˜440 nm). In another embodiment, the thickness of the encapsulation layer116may vary independent from the type of OLED light used at the sub-pixels108a,108b, and108c. The encapsulation layer in each sub-pixel are varied in thickness in order to protect deposited layers during etching of subsequent encapsulation layers.

The encapsulation layer116includes the non-conductive inorganic material, such as the silicon-containing material. The silicon-containing material may include silicon nitride (e.g., Si3N4) materials, silicon oxynitride materials (e.g., Si2N2O), silicon oxide materials (e.g., SiO2), or a combination thereof. In one embodiment, the first encapsulation layer116A includes silicon nitride materials, the second encapsulation layer116B includes a silicon oxynitride material, and the third encapsulation layer116C includes silicon oxide. The thicknesses of the encapsulation layer116may depend on the etch selectivity of the material of the encapsulation layer116. The silicon-containing materials can further be varied to change the optical properties of the encapsulation layer116. For example, the silicon-containing materials can be tuned to increase or decrease the refractive index. The difference in refractive index can also effect the etching rate of the encapsulation layer116. This allows for additional etch selectivity control of the encapsulation layer116. In one embodiment, the first encapsulation layer116A has a first refractive index, the second encapsulation layer1166has a second refractive index, and the third encapsulation layer116C has a third refractive index. In this embodiment, the first refractive index, the second refractive index, and the third refractive index are different from each other.

In one embodiment, at least one of the first encapsulation layer116A, the second encapsulation layer116B, and the third encapsulation layer116C may include at least two layers of the silicon-containing material. At least one of the first encapsulation layer116A, the second encapsulation layer116B, and the third encapsulation layer116C includes a composition for at least one of the layers of the silicon-containing material that is different from the compositions of the other encapsulation layers116. In a first example, the first encapsulation layer116A includes a silicon oxynitride material over a silicon nitride material. The second encapsulation layer116B includes a silicon oxide layer over a silicon nitride layer. The third encapsulation layer116C includes a silicon nitride layer over a silicon oxide layer. In a second example, the first encapsulation layer116A includes a silicon oxide layer over a silicon oxynitride layer. The second encapsulation layer116B includes a silicon nitride layer over a silicon oxynitride layer. The third encapsulation layer116C has a silicon oxynitride layer over a silicon oxide layer.

The encapsulation layer116may further be varied using different modes of deposition, e.g., atomic layer deposition (ALD), chemical vapor deposition (CVD), and physical vapor deposition (PVD). In one example, the first sub-pixel108aincludes silicon nitride deposited using CVD and silicon oxide deposited using ALD. The second sub-pixel108bincludes silicon nitride deposited using CVD and silicon oxynitride deposited using CVD. The third sub-pixel108cincludes silicon nitride deposited using CVD. The encapsulation layer116may further be varied between using an inductively coupled plasma (IDP) or a conductively coupled plasma (CCP) for the deposition processes.

By varying the encapsulation layer116compositions, deposition methods, and thicknesses, the encapsulation layer in each sub-pixel protects deposited layers during later processing and improves process yield and efficiency. The variation in encapsulation layer116thicknesses further controls the distance between the underside edge206and the top surface of the encapsulation layer116, as shown in sub-pixels108band108cinFIG.1AandFIG.2A. The distances control the amount of etching and deposition that occurs under the overhang structures110, leading to increased OLED material112protection during subsequent deposition and etching.

During evaporation deposition of the OLED material112, the underside edge206of the top structure110B defines the position of the OLED endpoint218. E.g., the OLED material112is evaporated at an OLED maximum angle that corresponds to the OLED vector212and the underside edge206ensures that the OLED material112is not deposited past the OLED endpoint218. During evaporation deposition of the cathode114, the underside edge206of the top structure110B defines the position of the cathode endpoint226. E.g., the cathode114is evaporated at a cathode maximum angle that corresponds to the cathode vector224and the underside edge206ensures that the cathode114is not deposited past the cathode endpoint226. The OLED angle θOLEDis less than the cathode angle θcathode.

FIG.3is a flow diagram of a method300for forming a sub-pixel circuit100, according to embodiments.FIGS.4A-4Kare schematic, cross-sectional views of a substrate102during the method300for forming the sub-pixel circuit100, according to embodiments described herein. The method300described herein provides for the ability to fabricate both the sub-pixel circuit100with the dot-type architecture101C and the sub-pixel circuit100with the line-type architecture101D.

At operation301, as shown inFIG.4A, a body structure layer402A and top structure layer402B are deposited over the substrate102. The body structure layer402A is disposed over the PDL structures126and the metal-containing layers104. The top structure layer402B is disposed over the body structure layer402A. The body structure layer402A corresponds to the body structure110A and the top structure layer402B corresponds to the top structure110B of the overhang structures110.

At operation302, as shown inFIG.4B, a resist406is disposed and patterned. The resist406is disposed over the top structure layer402B. The resist406is 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 resist406determines whether the resist is a positive resist or a negative resist. The resist406is patterned to form one of a pixel opening124A of the dot-type architecture101C or a pixel opening124B of the line-type architecture101D of a first sub-pixel108a. The patterning is one of a photolithography, digital lithography process, or laser ablation process.

At operation303, as shown inFIG.4C, portions of the top structure layer402B and the body structure layer402A exposed by the pixel opening124A,124B are removed. The top structure layer402B exposed by the pixel opening124A,124B may be removed a dry etch process or a wet etch process. The body structure layer402A exposed by the pixel opening124A,124B may be removed by a dry etch process of a wet etch process. Operation303forms the overhang structures110of the first sub-pixel108a. The etch selectivity between the materials of the top structure layer402B corresponding to the top structure110B and the body structure layer402A corresponding to the body structure110A and the etch processes to remove the exposed portions of the top structure layer402B and the body structure layer402A provide for the bottom surface107of the top structure110B being wider than the top surface105of the body structure110A to form the top extension109A that defines the overhang109(as shown inFIGS.1A,1B,2A, and2B). The shadowing of the overhang109provides for evaporation deposition the OLED material112and the cathode114.

At operation304, as shown inFIG.4D, the OLED material112of the first sub-pixel108a, the cathode114, and the encapsulation layer116are deposited. The shadowing of the overhang109provides for evaporation deposition each of the OLED material112and a cathode114. As further discussed in the corresponding description ofFIG.2, the shadowing effect of the overhang structures110define the OLED angle θOLED(shown inFIG.2A) of the OLED material112and the cathode angle θcathode(shown inFIG.2A) of the cathode114. The OLED angle θOLEDof the OLED material112and the cathode angle θcathodeof the cathode114result from evaporation deposition of the OLED material112and the cathode114. In one embodiment, the cathode114contacts the body structure110A of the overhang structures110. The encapsulation layer116is deposited over the cathode114with a thickness t1. In embodiments including capping layers, the capping layers are deposited between the cathode114and the encapsulation layer116. The capping layers may be deposited by evaporation deposition.

At operation305, as shown inFIG.4E, a resist408is formed in a well410of the first sub-pixel108a. In one embodiment, a thickness of the resist408is different from a thickness of the resist406. At operation306, as shown inFIGS.4F, the encapsulation layer116, the cathode114, and the OLED material112exposed by the resist408are removed. The encapsulation layer116, the cathode114, and the OLED material112exposed by resist408may be removed by wet etch or dry etch processes. The resist408is removed from the well, leaving behind the overhang structures110. At operation307, as shown inFIGS.4G, a resist412is disposed and patterned. In one embodiment, a thickness of the resist412is different from the thickness of the resist406and the resist408. The resist412is disposed over the top structure layer402B and the top structure1106of the first sub-pixel108a. The resist412is patterned to form one of the pixel opening124A of the dot-type architecture101C or the pixel opening124B of the line-type architecture101D of a second sub-pixel108b.

At operation308, as shown inFIG.4H, portions of the top structure layer402B and the body structure layer402A exposed by the pixel opening124A,1246of the second sub-pixel108bare removed. The top structure layer402B exposed by the pixel opening124A,124B may be removed a dry etch process or wet etch process. The body structure layer402A exposed by the pixel opening124A,124B may be removed by a dry etch process or a wet etch process. Operation308forms the overhang structures110of the second sub-pixel108b. The etch selectivity of the materials of the top structure layer402B corresponding to the top structure1106and the body structure layer402A corresponding to the body structure110A and the etch processes to remove the exposed portions of the top structure layer402B and the body structure layer402A provide for the bottom surface107of the top structure1106being wider than the top surface105of the body structure110A to form the top extension109A that defines the overhang109(as shown inFIG.1A). The shadowing of the overhang109provides for evaporation deposition the OLED material112and the cathode114.

At operation309, as shown inFIG.4I, the OLED material112of the second sub-pixel108b, the cathode114, and the encapsulation layer116are deposited. A resist414is formed in a well of the first sub-pixel108aand the OLED material112, the cathode114and the encapsulation layer116are deposited over the resist414. In one embodiment, the resist414has a thickness that is different from the thickness of the resist408and the resist412. In embodiments including capping layers, the capping layers are deposited between the cathode114and the encapsulation layer116. The capping layers may be deposited by evaporation deposition. The shadowing of the overhang109provides for evaporation deposition of the OLED material112and a cathode114. The shadowing effect of the overhang structures110define the OLED angle θOLEDof the OLED material112and the cathode angle θcathodeof the cathode114. The OLED angle θOLEDof the OLED material112and the cathode angle θcathodeof the cathode114result from evaporation deposition of the OLED material112and the cathode114. In one embodiment, the cathode114contacts the body structure110A of the overhang structures110. The encapsulation layer116is deposited over the cathode114with a thickness t2. In one embodiment, the thickness t2is lesser than the thickness t1. In another embodiment, the thickness t2is greater than the thickness t1.

At operation310, as shown inFIG.4J, a resist416is formed in a well of the second sub-pixel108b. In one embodiment, a thickness of the resist416is different from a thickness of the resist406, the resist408, and the resist412. At operation311, as shown inFIG.4K, the encapsulation layer116, the cathode114, and the OLED material112exposed by the resist416are removed. The encapsulation layer116, the cathode114, and the OLED material112exposed by resist416may be removed by wet etch or dry etch processes. The resist416is removed from the well, leaving behind the overhang structures110. Operations301-311described herein form the sub-pixel circuit100including two sub-pixels106. Operations306-310may be repeated for each addition sub-pixel, e.g. for a third and/or a fourth sub-pixel. The encapsulation layer116for a third sub-pixel108c, as shown inFIGS.1A and1B, has a thickness t3. Any additional pixels108nhave an encapsulation layer116with a thickness tn. In one embodiment, the thickness t3of the encapsulation layer116in sub-pixel108cis lesser than the thicknesses t1and t2. In another embodiment, the thickness t3of the encapsulation layer116in sub-pixel108cis greater than the thicknesses t1and t2. In another embodiment, the thickness t3of the encapsulation layer116in sub-pixel108cis lesser than the thickness t1and greater than the thickness t2. In another embodiment, the thickness t3of the encapsulation layer116in sub-pixel108cis greater than the thickness t1and lesser than the thickness t2. In another embodiment, the thickness of the encapsulation layer116is increased as the wavelength of light emitted increases. In another embodiment, the thickness of the encapsulation layer116is decreased as the wavelength of light emitted increases.

Thicknesses, compositions, and deposition methods of the encapsulation layer116may be varied, as described above. By varying the encapsulation layer116compositions and deposition methods to create variations in thicknesses, the encapsulation layer116protects the deposited OLED material112from damage during layering and improves process yield and efficiency. The variation in encapsulation layer116thicknesses further controls the distance between the underside edge206and the top surface of the encapsulation layer116, as shown in sub-pixels108band108cinFIG.1andFIG.2. The distances control the amount of etching and deposition that occurs under the overhang structures110, leading to increased OLED material112protection during subsequent deposition and etching.

FIG.5is a flow diagram of a method500for forming a sub-pixel circuit100.FIGS.6A-6Hare schematic, cross-sectional views of a substrate102during the method500for forming the sub-pixel circuit100according to embodiments described herein.

At operation501, as shown inFIG.6A, a body structure layer402A and a top structure layer402B are deposited over the substrate102. The body structure layer402A is disposed over the PDL structures126and the metal-containing layers104. The top structure layer402B is disposed over the body structure layer402A. The body structure layer402A corresponds to the body structure110A and the top structure layer402B corresponds to top structure110B of the overhang structures110. A resist406is disposed and patterning over the top structure layer402B to expose pixel openings124A,124B. At operation502, as shown inFIG.6B, the overhang structure portions of the top structure layer402B and the body structure layer402A exposed by the pixel opening124A,124B are removed. The top structure layer402B exposed by the pixel opening124A,124B may be removed a dry etch process or a wet etch process. The body structure layer402A exposed by the pixel opening124A,124B may be removed by a dry etch process or a wet etch process.

At operation503, as shown inFIG.6C, the OLED material112of the first sub-pixel108a, the cathode114, and the encapsulation layer116are deposited. In embodiments including capping layers, the capping layers are deposited between the cathode114and the encapsulation layer116. The capping layers may be deposited by evaporation deposition. As further discussed in the corresponding description ofFIG.2B, the shadowing effect of the overhang structures110define the OLED angle θOLED(shown inFIG.2A) of the OLED material112and the cathode angle θcathode(shown inFIG.2A) of the cathode114. The OLED angle θOLEDof the OLED material112and the cathode angle θcathodeof the cathode114result from evaporation deposition of the OLED material112and the cathode114. In one embodiment, the cathode114contacts the body structure110A of the overhang structures110. The encapsulation layer116is deposited over the cathode114. The encapsulation layer116of sub-pixel108ahas the gaps150partially underneath the top structure110B. Each of the gaps150is defined by the first portion151, the second portion152, the third portion153, and the first portion151contacting the third portion153of the encapsulation layer116. The first portion151of the encapsulation layer116is disposed over the cathode114. In some embodiments, the first portion151contacts the cathode114. The second portion152of the encapsulation layer116is disposed over the sidewall111of the body structure110A. In some embodiments, the second portion152contacts the sidewall111of the body structure110A. The third portion153of the encapsulation layer116is disposed under the underside surface117of the top extension109A of the top structure110B. In some embodiments, the third portion153contacts the underside surface117of the top extension109A of the top structure110B. The first portion151of the encapsulation layer116contacts the third portion153of the encapsulation layer116. The gaps150are sealed by the contact of the first portion151and the third portion153.

At operation504, as shown inFIG.6D, a resist602is formed in a well of the first sub-pixel108a. Due to the contact of the first portion151of the encapsulation layer116and the third portion153of the encapsulation layer116the resist602cannot enter the gaps150. The resist602cannot get underneath the top structure110B due to the gaps150and the encapsulation layer116. At operation505, as shown inFIG.6E, the encapsulation layer116, the cathode114, and the OLED material112exposed by the resist602are removed. The encapsulation layer116, the cathode114, and the OLED material112exposed by resist602may be removed by wet etch processes. The resist602is removed. Since the resist602is stopped from being trapped under the top structure1106, the resist602is removed without leaving any resist602behind.

At operation506, as shown inFIG.6F, the OLED material112of the second sub-pixel108b, the cathode114, and the encapsulation layer116are deposited. In embodiments including capping layers, the capping layers are deposited between the cathode114and the encapsulation layer116. The capping layers may be deposited by evaporation deposition. The shadowing of the overhang109provides for evaporation deposition each of the OLED material112and a cathode114. The shadowing effect of the overhang structures110define the OLED angle θOLEDof the OLED material112and the cathode angle θcathodeof the cathode114. The OLED angle θOLEDof the OLED material112and the cathode angle θcathodeof the cathode114result from evaporation deposition of the OLED material112and the cathode114. In one embodiment, the cathode114contacts the body structure110A of the overhang structures110. The encapsulation layer116is deposited over the cathode114. The encapsulation layer116of sub-pixel108bhas the gaps150partially underneath the top structure1106. Each of the gaps150is defined by the first portion151, the second portion152, the third portion153, and the first portion151contacting the third portion153of the encapsulation layer116. The first portion151of the encapsulation layer116is disposed over the cathode114. In some embodiments, the first portion151contacts the cathode114. The second portion152of the encapsulation layer116is disposed over the sidewall111of the body structure110A. In some embodiments, the second portion152contacts the sidewall111of the body structure110A. The third portion153of the encapsulation layer116is disposed under the underside surface117of the top extension109A of the top structure1106. In some embodiments, the third portion153contacts the underside surface117of the top extension109A of the top structure1106. The first portion151of the encapsulation layer116contacts the third portion153of the encapsulation layer116. The gaps150are sealed by the contact of first portion151and the third portion153.

At operation507, as shown inFIG.6G, a resist606is formed in a well of the second sub-pixel108b. Due to the contact of the first portion151of the encapsulation layer116and the third portion153of the encapsulation layer116the resist606cannot enter the gaps150. The resist606cannot get underneath the top structure110B due to the gaps150and the encapsulation layer116. At operation508, as shown inFIG.6H, the encapsulation layer116, the cathode114, and the OLED material112exposed by the resist606are removed. The encapsulation layer116, the cathode114, and the OLED material112exposed by resist606may be removed by wet etch processes. The resist606is removed. Since the resist606is stopped from being trapped under the top structure110B, the resist606is removed without leaving any resist602behind.

Operations501-508described herein form the sub-pixel circuit100including two or more sub-pixels106. Operations505-508may be repeated for each addition sub-pixel, e.g. for a third and/or a fourth sub-pixel. The encapsulation layer116for a third sub-pixel108c, as shown inFIG.1B, has the gaps150partially underneath the top structure110B. Each of the gaps150is defined by the first portion151, the second portion152, the third portion153, and the first portion151contacting the third portion153of the encapsulation layer116. The first portion151of the encapsulation layer116is disposed over the cathode114. In some embodiments, the first portion151contacts the cathode114. The second portion152of the encapsulation layer116is disposed over the sidewall111of the body structure110A. In some embodiments, the second portion152contacts the sidewall111of the body structure110A. The third portion153of the encapsulation layer116under the underside surface117of the top extension109A of the top structure110B. In some embodiments, the third portion153contacts the underside surface117of the top extension109A of the top structure110B. The first portion151of the encapsulation layer116contacts the third portion153of the encapsulation layer116. The gaps150are sealed by the contact of first portion151and the third portion153. Any additional pixels108nhave an encapsulation layer116with the gaps150sealed by the contact of the first portion151and the third portion153.

In summation, described herein are device relate to sub-pixel circuits and methods of forming sub-pixel circuits that may be utilized in a display such as an organic light-emitting diode (OLED) display. 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 may be utilized for deposition of an OLED material and cathode. The overhang structures define deposition angles, i.e., provide for a shadowing effect during evaporation deposition, for each of the OLED material and the cathode such the OLED material does not contact the body structure and the cathode contacts the body structure according to some embodiments. The encapsulation layer of a respective sub-pixel is disposed over the cathode with the encapsulation layer extending under at least a portion of each of the adjacent overhang structures and over a sidewall of each of the adjacent overhang structures. The encapsulation layers in each sub-pixel are varied in thickness in order to protect deposited layers during etching of encapsulation subsequent layers. The variation in thickness can be descending, ascending, or dependent on the OLED material deposited (e.g., the color of the OLED). The gaps150in the encapsulation layer116are present and sealed to prevent resist from entering under the top structure1106. The resists602,606are prevented from becoming trapped and can be properly removed along with the encapsulation layer116, cathode114, and OLED material112.