A method for fabricating a pixel electrode structure of a display device

Abstract

The application discloses a preparation method of a pixel electrode structure of a display device, and comprises the following steps: forming a reflective metal layer; forming a first transparent microcavity layer; forming a patterned first sacrificial layer, the first sacrificial layer blocks a first pixel area and a third pixel area; growing a second transparent microcavity layer, then removing the first sacrificial layer to form a patterned second transparent microcavity layer; and forming a patterned third transparent microcavity layer by the same method; forming a blocking layer in each pixel area, the size of the blocking layer is smaller than the second transparent microcavity layer and the third transparent microcavity layer; etching the transparent microcavity layer and the reflective metal layer to form a patterned first transparent microcavity layer and a reflective layer; and modifying the edges of the second transparent microcavity layer and the third transparent microcavity layer. The preparation method can make each pixel area have a microcavity structure with different cavity lengths, independently adjust the color of a sub-pixel through the microcavity, reduce the light loss caused by a color filter, and improve the brightness of a silicon-based OLED display screen.

Description

Technical Field

[0001] This invention relates to the field of display technology, and particularly to the pixel electrode structure and formation method of OLED display devices. Background Technology

[0002] Organic light-emitting diodes (OLEDs) are a display technology that emerged in the early 21st century. They have advantages such as being thin and light, having low power consumption, and having good display effects. They are currently widely used in mobile phones, tablets and other fields.

[0003] Silicon-based OLED devices differ from conventional glass-substrate OLED devices in that they use silicon wafers to fabricate driving circuits, resulting in manufacturing precision far exceeding that of glass-substrate products. Their PPI (Pixels per Inch) can typically reach over 1000, making them widely applicable in the VR / AR field.

[0004] Typically, silicon-based OLED subpixels are between 3 and 10 μm. At this size, the vapor deposition masks used in the conventional OLED industry are difficult to apply to silicon-based OLEDs. This results in silicon-based OLED products generally using single-layer or multi-layer devices to directly emit white light, and then using color filters to generate red, green, and blue pixels. The significant light loss generated by this method leads to low display brightness. Summary of the Invention

[0005] This invention provides a method for fabricating pixel electrode structures for display devices, which enables silicon-based OLED devices to have sub-pixels with different microcavity lengths. By adjusting the microcavities, the sub-pixels of the display screen can directly generate light of their corresponding colors, thereby reducing light loss caused by color filters and improving the brightness of silicon-based OLED displays.

[0006] To achieve the above effects, the present invention provides a method for fabricating a pixel electrode structure for a display device, comprising:

[0007] A substrate with an OLED driving circuit, the substrate including a first pixel region, a second pixel region, and a third pixel region corresponding to different color pixels;

[0008] A reflective metal layer and a first transparent microcavity layer are fabricated on a substrate;

[0009] A patterned first sacrificial layer is formed on the first transparent microcavity layer by photolithography. The first sacrificial layer blocks the first pixel area and the third pixel area, and its opening size is smaller than that of the second pixel area.

[0010] A second transparent microcavity layer is grown on the first sacrificial layer, and then the first sacrificial layer and the second transparent microcavity layer on it are removed by peeling to form a patterned second transparent microcavity layer.

[0011] The third transparent microcavity layer is formed using the same method as the second transparent microcavity layer.

[0012] A barrier layer is formed in each pixel area by photolithography. The size of the barrier layer is smaller than that of the second and third transparent microcavity layers. The transparent microcavity layers and the reflective metal layer are etched to form a patterned first transparent microcavity layer and a reflective layer. At the same time, the edges of the second and third transparent microcavity layers are modified.

[0013] Secondly, the present invention also provides a method for fabricating a pixel electrode structure for a display device, comprising:

[0014] A substrate with an OLED driving circuit, the substrate including a first pixel region, a second pixel region, and a third pixel region corresponding to different color pixels;

[0015] A patterned first sacrificial layer is formed on a substrate by photolithography. The first sacrificial layer blocks the second pixel area and the third pixel area. The opening size of the first sacrificial layer is smaller than that of the first pixel area.

[0016] A reflective metal layer and a first transparent microcavity layer are grown on the first sacrificial layer. Then, the first sacrificial layer and the first transparent microcavity layer and the reflective metal layer on it are removed by a peeling method to form a patterned reflective metal layer and a first transparent microcavity layer.

[0017] The same method is used to form the patterned reflective metal layer and the first transparent microcavity layer to form the patterned reflective metal layer and the second transparent microcavity layer, as well as to form the patterned reflective metal layer and the third transparent microcavity layer.

[0018] Thirdly, the present invention also provides a method for fabricating a pixel electrode structure for a display device, comprising:

[0019] A substrate with an OLED driving circuit, the substrate including a first pixel region, a second pixel region, and a third pixel region corresponding to different color pixels;

[0020] A reflective metal layer and an intermediate layer are grown on a substrate. A patterned barrier layer is formed on the intermediate layer using photolithography. The reflective metal layer and the intermediate layer are etched. Finally, the barrier layer is removed to obtain the patterned reflective metal layer and the intermediate layer.

[0021] A protective layer is grown on a patterned reflective metal layer and an intermediate layer. A patterned first sacrificial layer is formed on the protective layer by photolithography. The first sacrificial layer blocks the second pixel area and the third pixel area. The opening size of the first sacrificial layer is smaller than that of the first pixel area.

[0022] A first transparent microcavity layer is grown, and then the first sacrificial layer and the first transparent microcavity layer on it are removed by peeling to form a patterned first transparent microcavity layer.

[0023] And using the same method as forming the first patterned transparent microcavity layer, a second patterned transparent microcavity layer and a third patterned transparent microcavity layer are formed;

[0024] A patterned barrier layer is formed in each pixel area using photolithography. Each barrier layer is located within each pixel area, and the size of the barrier layer is smaller than the size of the corresponding transparent microcavity layer.

[0025] The edges of the transparent microcavity layer are modified by etching; finally, the barrier layer is removed.

[0026] Preferably, the present invention utilizes a sacrificial layer and forms a patterned transparent microcavity layer using a peeling method.

[0027] Preferably, the present invention uses an etching method to remove burrs caused by the stripping method.

[0028] Preferably, the etching method of the present invention is dry etching, and the etching gas used is one or more of Ar, Cl, and O2.

[0029] Preferably, the etch barrier layer pattern size of the present invention is smaller than that of the patterned transparent microcavity layer, and the linewidth difference is between 300 and 800 nm.

[0030] The method for forming patterned transparent microcavity layers provided by this invention avoids etching processes, solves the problem of difficult etching of metal compound materials, avoids the problem of metal layers being easily corroded by alkaline developing solutions, has low process difficulty, and improves the feasibility of large-scale production. Attached Figure Description

[0031] Figures 1 to 10 This is a schematic diagram of the structure corresponding to each step in the first embodiment of the pixel electrode structure formation method of the present invention.

[0032] Figures 11 to 20 This is a schematic diagram of the structure corresponding to each step in the second embodiment of the pixel electrode structure formation method of the present invention.

[0033] Figures 21 to 40 This is a schematic diagram of the structure corresponding to each step in the third embodiment of the pixel electrode structure formation method of the present invention. Detailed Implementation

[0034] The following description, in conjunction with the accompanying drawings and embodiments, provides a further explanation and illustration of a pixel electrode structure fabrication method according to the present invention.

[0035] This invention provides a method for fabricating a pixel electrode structure, comprising:

[0036] A reflective metal layer and a first transparent microcavity layer are formed on the driving circuit substrate, wherein the transparent microcavity is made of a metal compound material.

[0037] A patterned second transparent microcavity layer and a third transparent microcavity layer are sequentially formed on the driving circuit substrate. The transparent microcavities are made of a metal compound material. The second and third transparent microcavity layers are located within an independent light-emitting sub-pixel, and the second and third transparent microcavity layers have different thicknesses. The patterning method includes: forming a patterned sacrificial layer on the substrate, and growing the transparent microcavity layers on the sacrificial layer. The openings of the patterned sacrificial layer are located within the independent light-emitting sub-pixel.

[0038] The sacrificial layer and the transparent microcavity layer on the sacrificial layer are removed to form a patterned transparent microcavity layer.

[0039] An etch stop layer is formed on the driving circuit substrate, the reflective metal layer, and the first, second, and third transparent microcavity layers. The etch stop layer is located within each individual light-emitting sub-pixel and its size is smaller than the second and third transparent microcavity layers. The etch selectivity ratio of the etch stop layer to the reflective metal layer and the first transparent microcavity layer is less than 1:10.

[0040] The reflective metal layer and the first transparent microcavity layer are etched, and the etching barrier layer is removed.

[0041] The present invention also provides a method for fabricating a pixel electrode structure, comprising:

[0042] A patterned first reflective layer and transparent microcavity layer, a second reflective layer and transparent microcavity layer, and a third reflective layer and transparent microcavity layer are sequentially formed on a driving circuit substrate. The reflective layers and transparent microcavity layers are located within independent light-emitting sub-pixels. The patterning method includes:

[0043] A patterned sacrificial layer is formed on a substrate, and the reflective layer and transparent microcavity layer are grown on the sacrificial layer. The openings of the patterned sacrificial layer are located within individual light-emitting sub-pixels.

[0044] The sacrificial layer, the reflective layer on the sacrificial layer, and the transparent microcavity layer are removed to form a patterned reflective layer and a transparent microcavity layer.

[0045] The present invention also provides a method for fabricating a pixel electrode structure, comprising:

[0046] A pixel-patterned reflective metal layer and an intermediate layer are formed on the driving circuit substrate. The barrier layer can be a metal compound material or a compound material.

[0047] A protective layer is fabricated on the driving circuit substrate and on the pixel-patterned reflective metal layer and intermediate layer. The protective layer is made of a compound material.

[0048] A patterned first transparent microcavity layer, a second transparent microcavity layer, and a third transparent microcavity layer are sequentially formed on the driving circuit substrate. The transparent microcavities are made of a metal compound material. The first, second, and third transparent microcavity layers are located within an independent light-emitting sub-pixel, and the first, second, and third transparent microcavity layers have different thicknesses. The patterning method includes: forming a patterned sacrificial layer on the substrate. The opening of the patterned sacrificial layer is located within the independent light-emitting sub-pixel, and its size is larger than the patterned reflective metal layer and intermediate layer of the pixel. The etching selectivity ratio of the sacrificial layer to the protective layer is less than 1:10.

[0049] The protective layer is etched, and the etching barrier layer is removed.

[0050] A transparent microcavity layer is grown on the substrate and a patterned sacrificial layer, and the sacrificial layer and the transparent microcavity layer on the sacrificial layer are removed to form a patterned transparent microcavity layer.

[0051] An etch stop layer is formed on the driving circuit substrate, the reflective metal layer, and the first, second, and third transparent microcavity layers. The etch stop layer is located within each individual light-emitting sub-pixel and its size is smaller than the second and third transparent microcavity layers. The etch selectivity ratio of the etch stop layer to the reflective metal layer and the first transparent microcavity layer is less than 1:10.

[0052] The reflective metal layer and the first transparent microcavity layer are etched, and the etching barrier layer is removed.

[0053] Example 1, Figures 1 to 10 This is a schematic diagram of the structure corresponding to each step in the preparation method of the first pixel electrode structure of the present invention.

[0054] refer to Figure 1 A substrate 100 with a silicon-based OLED driving circuit is provided. 110 is a driving circuit lead structure responsible for conducting the driving voltage to the anode of the silicon-based OLED device. The substrate of the silicon-based OLED driving circuit may have multiple pixel regions. In this embodiment, referring to the red, green, and blue pixels of a conventional display device, the substrate has a first pixel region, a second pixel region, and a third pixel region.

[0055] A reflective metal layer 200 and a first transparent microcavity layer 210 are fabricated on a substrate 100. The reflective metal layer 200 also serves as the anode of the silicon-based OLED device.

[0056] The reflective metal layer exhibits good reflectivity and conductivity. The transparent microcavity layer possesses characteristics such as good conductivity, high transparency, and a work function that matches OLED devices. The reflective metal layer can be made of metals such as Al, Ag, or Cu, and the transparent microcavity layer can be made of one or more of ITO, IZO, and ZnO.

[0057] The thickness of the first transparent microcavity layer is between 5 and 20 nm.

[0058] refer to Figure 2 A patterned first sacrificial layer 300 is fabricated on the first transparent microcavity layer 210 using photolithography, with its opening located in the second pixel region. The first sacrificial layer is made of photoresist, which can be positive photoresist, negative photoresist, or multilayer photoresist, and its thickness is between 0.5 and 2 μm.

[0059] refer to Figure 3 A second transparent microcavity layer 211 is grown on the first sacrificial layer 300. The material of the second transparent microcavity layer can be one or more of ITO, IZO, and ZnO, and the thickness of the transparent microcavity layer is between 5 and 200 nm.

[0060] refer to Figure 4 The first sacrificial layer 300 is removed by peeling, and the second transparent microcavity layer attached thereto is also removed. The remaining part is the patterned second transparent microcavity layer 211, which is located in the second pixel area.

[0061] refer to Figures 5 to 7 The method for forming a patterned third transparent microcavity layer 212 is similar to... Figures 2 to 4 The method for forming a patterned second transparent microcavity layer is consistent with that used in the method described above, wherein the third transparent microcavity layer is located in the third pixel region.

[0062] The thickness of the second and third transparent microcavity layers is between 5 and 300 nm. The thickness and material of the first, second, and third transparent microcavity layers may or may not be the same.

[0063] refer to Figure 8 A patterned barrier layer 302 is prepared by photolithography, and the size of the barrier layer is smaller than that of the second and third transparent microcavity layers.

[0064] refer to Figures 9 to 10 The first transparent microcavity layer 210 and the reflective metal layer 200 are patterned by etching. Since the transparent microcavity layer is made of metal oxides such as ITO, IZO, and ZnO, it is usually difficult to etch. In this embodiment, Ar gas is used to etch it by physical bombardment.

[0065] It should be noted that in this embodiment, the patterned second and third transparent microcavity layers are formed using a peeling method. Due to the good film adhesion, residual burrs usually form at the edges of the pattern after peeling. Figures 9 to 10 The etching process can also be used to etch and modify the edge burrs of the second and third transparent microcavity layers, thereby preventing edge burrs from piercing the OLED film layer and causing short circuits or other abnormalities.

[0066] Through the above process, transparent microcavity layers with independent thickness or material are formed in the first pixel area, the second pixel area, and the third pixel area, thereby adjusting the microcavity of the OLED device.

[0067] Example 2, Figures 11 to 20 This is a schematic diagram of the structure corresponding to each step in the preparation method of the second pixel electrode structure of the present invention.

[0068] The substrate and peeling method used in this embodiment are the same as those in the first embodiment.

[0069] The difference from the first embodiment is that: in the first embodiment, a full-surface reflective metal layer 200 and a first transparent microcavity layer 210 are first formed, and then patterned by etching; in this embodiment, an independent reflective metal layer and a transparent microcavity layer are directly formed in the first pixel area, the second pixel area, and the third pixel area by peeling.

[0070] refer to Figures 11 to 20 The specific steps of Example 2 are as follows:

[0071] S11: A first sacrificial layer 310 is formed on the substrate 100, with its opening located in the first pixel region;

[0072] S12: Growing a reflective metal layer 201 and a first transparent microcavity layer 220;

[0073] S13: Peel off the first sacrificial layer and the first transparent microcavity layer attached thereto to form a patterned reflective metal layer 201 and a first transparent microcavity layer 220;

[0074] S14~S19: Referring to S11~S13, a patterned reflective metal layer 201, a second transparent microcavity layer 221, and a third transparent microcavity layer 222 are formed in the second pixel region and the third pixel region. The thickness and material of the first transparent microcavity layer, the second transparent microcavity layer, and the third transparent microcavity layer may be the same or different.

[0075] The advantage of this embodiment is that, in Embodiment 1, due to the high difficulty of the etching process of the transparent microcavity layer, the thickness of the first transparent microcavity layer can only be limited to between 5 and 20 nm; however, in this embodiment, the first transparent microcavity layer does not use an etching method, and the thickness can be selected between 5 and 300 nm.

[0076] Example 3, Figures 21 to 40 This is a schematic diagram of the structure corresponding to each step in the preparation method of the third pixel electrode structure of the present invention.

[0077] The substrate and peeling method used in this embodiment are the same as those in the first and second embodiments.

[0078] The difference from the first and second embodiments is that: in this embodiment, the reflective metal layer is first patterned, then a transparent microcavity layer is formed by a peeling process, and finally the edges of the patterned transparent microcavity layer are modified.

[0079] refer to Figures 21 to 24 The process of patterning the reflective metal layer involves forming independent reflective metal layers and intermediate layers in the first pixel area, the second pixel area, and the third pixel area, respectively. The steps are as follows:

[0080] A reflective metal layer 204 and an intermediate layer 24 are grown on a substrate 100. A patterned barrier layer 320 is formed on the intermediate layer 240 using photolithography. The reflective metal layer 204 and the intermediate layer 240 are etched. Finally, the barrier layer is removed. It should be noted that the intermediate layer can be made of a metal compound, such as TiN; it can also be made of common dielectric compounds, such as SiO2 or SiN. The main function of the intermediate layer is to protect the reflective metal layer from being eroded by the developer during photolithography. In this embodiment, TiN is used.

[0081] refer to Figure 25 A protective layer 250 is grown on the patterned reflective metal layer and the intermediate layer. The protective layer is made of a compound material, such as SiO2 or SiN. The function of the protective layer is to protect the sidewalls of the patterned reflective metal layer from being eroded by the developer during the subsequent patterning process. The etching selectivity ratio of the protective layer to the reflective metal layer is greater than 10:1.

[0082] Figures 26 to 29 The process of patterning the first transparent microcavity layer 230 involves the following steps:

[0083] S21: Reference Figure 26 A patterned sacrificial layer 321 is formed on the protective layer 250 by photolithography, and the opening of the sacrificial layer is located in the first pixel area.

[0084] S22: Reference Figure 27 The protective layer 250 is etched to expose the patterned reflective metal layer and intermediate layer in the first pixel area.

[0085] S23: Reference Figures 28 to 29First, the first transparent microcavity layer is grown, and then the sacrificial layer 321 and the transparent microcavity layer attached thereto are removed by peeling method to form a patterned first transparent microcavity layer 230.

[0086] Figures 30 to 37 The formation process of the second and third transparent microcavity layers is illustrated in the diagram. The specific steps are shown in S21 to S22.

[0087] Figures 38 to 40 The steps for edge modification of the transparent microcavity layer are as follows:

[0088] First, a patterned barrier layer 325 is formed in each pixel area using photolithography. Each barrier layer is located within each pixel area and its size is smaller than the corresponding transparent microcavity layer size. Then, the edges of the transparent microcavity layer are modified using etching. Finally, the barrier layer is removed.

[0089] The advantages of this embodiment are: ① Compared with embodiment 1, the first transparent microcavity layer in this embodiment does not use an etching method, and the thickness can be selected between 5 and 300 nm; ② Compared with embodiment 2, the reflective metal layer in this embodiment is covered by the transparent microcavity layer, which can resist corrosion by the developing solution, so the edge modification process of the transparent microcavity layer can be performed.

Claims

1. A method for fabricating a pixel electrode structure for a display device, characterized in that, include: A substrate with an OLED driving circuit, the substrate including a first pixel region, a second pixel region, and a third pixel region corresponding to different color pixels; A reflective metal layer and a first transparent microcavity layer are fabricated on a substrate; A patterned first sacrificial layer is formed on the first transparent microcavity layer by photolithography. The first sacrificial layer blocks the first pixel area and the third pixel area, and its opening size is smaller than that of the second pixel area. A second transparent microcavity layer is grown on the first sacrificial layer, and then the first sacrificial layer and the second transparent microcavity layer on it are removed by peeling to form a patterned second transparent microcavity layer. The third transparent microcavity layer is formed using the same method as the second transparent microcavity layer. A barrier layer is formed in each pixel area by photolithography. The size of the barrier layer is smaller than that of the second and third transparent microcavity layers. The transparent microcavity layers and the reflective metal layer are etched to form a patterned first transparent microcavity layer and a reflective layer. At the same time, the edges of the second and third transparent microcavity layers are modified.

2. A method for fabricating a pixel electrode structure for a display device, characterized in that, include: A substrate with an OLED driving circuit, the substrate including a first pixel region, a second pixel region, and a third pixel region corresponding to different color pixels; A patterned first sacrificial layer is formed on a substrate by photolithography. The first sacrificial layer blocks the second pixel area and the third pixel area. The opening size of the first sacrificial layer is smaller than that of the first pixel area. A reflective metal layer and a first transparent microcavity layer are grown on the first sacrificial layer. Then, the first sacrificial layer and the first transparent microcavity layer and the reflective metal layer on it are removed by a peeling method to form a patterned reflective metal layer and a first transparent microcavity layer. The same method is used to form the patterned reflective metal layer and the first transparent microcavity layer to form the patterned reflective metal layer and the second transparent microcavity layer, as well as to form the patterned reflective metal layer and the third transparent microcavity layer.

3. A method for fabricating a pixel electrode structure for a display device, characterized in that, include: A substrate with an OLED driving circuit, the substrate including a first pixel region, a second pixel region, and a third pixel region corresponding to different color pixels; A reflective metal layer and an intermediate layer are grown on a substrate. A patterned barrier layer is formed on the intermediate layer using photolithography. The reflective metal layer and the intermediate layer are etched. Finally, the barrier layer is removed to obtain the patterned reflective metal layer and the intermediate layer. A protective layer is grown on a patterned reflective metal layer and an intermediate layer. A patterned first sacrificial layer is formed on the protective layer by photolithography. The first sacrificial layer blocks the second pixel area and the third pixel area. The opening size of the first sacrificial layer is smaller than that of the first pixel area. A first transparent microcavity layer is grown, and then the first sacrificial layer and the first transparent microcavity layer on it are removed by peeling to form a patterned first transparent microcavity layer. And using the same method as forming the first patterned transparent microcavity layer, a second patterned transparent microcavity layer and a third patterned transparent microcavity layer are formed; A patterned barrier layer is formed in each pixel area using photolithography. Each barrier layer is located within each pixel area, and the size of the barrier layer is smaller than the size of the corresponding transparent microcavity layer. The edges of the transparent microcavity layer are modified by etching; finally, the barrier layer is removed.

4. The preparation method according to claim 1, 2, or 3, characterized in that, Using a sacrificial layer, a patterned transparent microcavity layer is formed by peeling.

5. The preparation method according to claim 1 or 3, wherein an etching method is used to remove the burrs caused by the stripping method.

6. The preparation method according to claim 5, characterized in that, The etching method is dry etching, and the etching gas used is one or more of Ar, Cl, and O2.

7. The preparation method according to claim 5, characterized in that, The etch barrier layer pattern size is smaller than the patterned transparent microcavity layer, with a linewidth difference between 300 and 800 nm.

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