OLED (Organic Light Emitting Diode) anode, preparation method thereof and micro OLED display

Abstract

The invention provides an OLED (Organic Light Emitting Diode) anode, a preparation method thereof and a micro OLED display. The OLED anode comprises a substrate and at least two OLED anode modules which are distributed on the surface of one side of the substrate at intervals; the OLED anode module comprises a bottom anode metal reflecting layer, a middle anode metal reflecting layer, a top anode metal reflecting layer and a transparent conducting layer which are stacked in the direction away from the substrate; the bottom anode metal reflecting layer is trapezoidal, and the taper angle is greater than or equal to 75 degrees; and the side wall of the middle anode metal reflecting layer is steep and flat. According to the OLED anode provided by the invention, the side wall of the middle anode metal reflecting layer is steep and flat and shows a form which is not corroded by etching gas, and the taper angle of the bottom anode metal reflecting layer with the trapezoidal shape is greater than or equal to 75 degrees, so that the taper of the bottom anode metal reflecting layer is further improved, the Pixel aperture opening ratio of an OLED is favorably improved, and excellent product efficiency is obtained.

Description

Technical Field

[0001] The invention belongs to the field of display technology, and in particular relates to an OLED anode and a preparation method thereof, and a micro OLED display. Background Art

[0002] Micro organic light-emitting diode (OLED) displays have the characteristics of self-luminescence, wide viewing angle, high brightness, high lumen efficiency, low operating voltage and fast response time. They are considered to be one of the display technologies with great potential, and can meet consumers' new demands for display technology and gradually become the mainstream direction.

[0003] If solution etching technology is used on large-sized substrates, the uniformity of stripping depends on the temperature and concentration of the solution, which will cause uneven pixel patterns on large-sized substrates, and even some metals cannot be stripped. Since the anode reflective layer mainly consists of metal layers such as Al and Ti, Al has a face-centered cubic crystal structure, and Ti has a close-packed hexagonal crystal structure with strong corrosion resistance. Therefore, ordinary dry etching of Ti requires extremely strong etching gas to achieve, which indirectly causes relatively severe corrosion to Al; in addition, the bottom taper (taper angle) of the anode reflective layer in solution etching / ordinary dry etching is small, and the critical dimension (CD) size in the bottom anode reflective layer is limited due to the safe coverage of the pixel definition layer, which indirectly affects the size of the pixel (pixel) aperture ratio.

[0004] The prior art has disclosed the use of chlorine, boron trichloride, etc. to etch the Ti / Al metal in the anode reflective layer at one time, allowing each pixel to work independently. However, the highly corrosive gas of the anode etching can easily cause strong indentation of the metal in the anode reflective layer, resulting in multiple dark spots and other undesirable phenomena. There are problems such as Al corrosion of the anode reflective layer metal and small taper of the bottom layer of the anode reflective layer, which also indirectly affects the taper of the transparent conductive layer, resulting in a lower overall aperture ratio of the OLED and reduced product efficiency.

[0005] Therefore, it is urgent to enhance the protection of the anode reflective layer metal and further improve the taper of the underlying anode metal reflective layer, thereby increasing the Pixel aperture ratio of the OLED, which is a technical problem that needs to be solved. Summary of the invention

[0006] In view of the shortcomings of the prior art, the object of the present invention is to provide an OLED anode and a preparation method thereof and a micro OLED display. In the OLED anode provided by the present invention, the side wall of the middle anode metal reflective layer is steep and flat, showing a morphology that is not corroded by etching gas, and the taper angle of the bottom anode metal reflective layer with a trapezoidal morphology is ≥75°, indicating that the taper of the bottom anode metal reflective layer is further improved, which is beneficial to improving the pixel aperture ratio of the OLED and obtaining excellent product efficiency.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides an OLED anode, which includes a substrate and at least two OLED anode modules arranged on a surface of one side of the substrate and spaced apart from each other.

[0009] The OLED anode module includes a bottom anode metal reflective layer, a middle anode metal reflective layer, a top anode metal reflective layer and a transparent conductive layer which are stacked in a direction away from the substrate.

[0010] The bottom anode metal reflective layer has a trapezoidal shape, and a taper angle of ≥75°; the side wall of the middle anode metal reflective layer is steep and flat.

[0011] In the OLED anode provided by the present invention, the side wall of the middle anode metal reflective layer is steep and flat, showing a morphology that is not corroded by the etching gas, and the taper angle of the trapezoidal bottom anode metal reflective layer is ≥75°, indicating that the taper of the bottom anode metal reflective layer is further improved, which is beneficial to improving the Pixel aperture ratio of the OLED and obtaining excellent product efficiency.

[0012] It should be noted that the taper angle refers to the angle between the bottom surface of the bottom anode metal reflective layer and the inclined surface of the bottom anode metal reflective layer.

[0013] In the present invention, the taper angle is ≥75°, for example, it can be 75°, 80°, 85° or 88°.

[0014] It should be noted that “the side wall is steep and flat” means that the side wall of the middle anode metal reflective layer is smooth, uniform and complete, and is not corroded to form grooves.

[0015] Preferably, the taper angle is 75°-80°.

[0016] In the present invention, considering that a too large taper angle may cause fence-like defects, lines or uneven structures in the transparent conductive layer, and the side wall of the middle anode metal reflective layer may be corroded, the preferred taper angle is 75°-80°.

[0017] Preferably, the top surface width of the bottom anode metal reflective layer is smaller than the bottom surface width of the bottom anode metal reflective layer.

[0018] Preferably, the top surface of the bottom anode metal reflective layer coincides with the bottom surface of the middle anode metal reflective layer, and the shortest distance between adjacent OLED anode modules is denoted as K, K≥0.6μm, for example, it can be 0.6μm, 0.7μm, 0.8μm, 0.9μm, 1μm, 1.2μm or 1.5μm, etc.

[0019] In the present invention, K is limited to 0.6 μm, which can effectively reduce the etching load effect caused by etching the transparent conductive layer to achieve the interval arrangement, avoid etching residues, and the occurrence of bright spots. If the K value is too small, the subsequent etching gas dissociation plasma reaction is hindered, resulting in the presence of residual reflective metal of the bottom anode, and adjacent pixels are not completely independent, resulting in bright spots.

[0020] Preferably, the material of the bottom anode metal reflective layer and the top anode metal reflective layer independently includes TiN and / or Ti.

[0021] Preferably, the material of the middle anode metal reflective layer includes Al.

[0022] Preferably, the material of the transparent conductive layer includes any one of ITO (indium tin oxide), FTO (fluorine-doped tin oxide) or IZO (indium zinc oxide), or a combination of at least two of them.

[0023] Preferably, the transparent conductive layer has a trapezoidal morphology, and the bottom surface of the transparent conductive layer coincides with the top surface of the top anode metal reflective layer.

[0024] Preferably, the thickness of the bottom anode metal reflective layer is 80-100 nm, for example, 80 nm, 85 nm, 90 nm, 95 nm or 100 nm.

[0025] Preferably, the thickness of the middle anode metal reflective layer is 80-90 nm, for example, 80 nm, 82 nm, 84 nm, 86 nm, 88 nm or 90 nm.

[0026] In the present invention, a middle anode metal reflective layer with an appropriate thickness is conducive to ensuring a high light reflectivity while taking into account both cost and device performance; and it can ensure that the middle anode metal reflective layer has a low resistance, so that the current can be evenly distributed on the OLED anode, thereby ensuring the uniformity of OLED device light emission; in addition, at a reasonable thickness, the reflectivity of the middle anode metal reflective layer has reached a relatively saturated state, which can ensure the stability of the structure, so that the three-layer structure is not prone to delamination, falling off, etc. during the preparation process and subsequent use.

[0027] Preferably, the thickness of the top anode metal reflective layer is 3-8 nm, for example, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm or 8 nm.

[0028] In the present invention, the thinner top anode metal reflective layer is beneficial to reducing the absorption of light by the layer, so that more light can pass through the layer to the middle anode metal reflective layer; it is beneficial to modify the surface of the middle anode metal reflective layer to a certain extent, further improving the flatness of the entire anode surface; it can serve as a protective barrier to improve the chemical stability and oxidation resistance of the anode and extend the service life of the OLED device.

[0029] In a second aspect, the present invention provides a method for preparing an OLED anode as described in the first aspect, the preparation method comprising the following steps:

[0030] A substrate is provided, on the surface of which a first anode metal reflective layer, a second anode metal reflective layer, a third anode metal reflective layer and a transparent conductive layer are stacked, and the transparent conductive layers are distributed on the top surface of the third anode metal reflective layer at intervals.

[0031] The third anode metal reflective layer and the second anode metal reflective layer between adjacent transparent conductive layers are first etched to form a partition area and expose the first anode metal reflective layer.

[0032] Oxygen-containing gas and inert gas are introduced to passivate the sidewalls of the second anode metal reflective layer after the first etching to form a protective layer, and then the first anode metal reflective layer at the bottom of the partition area is second etched to obtain the OLED anode.

[0033] In the preparation method provided by the present invention, before etching the third anode metal reflective layer, the side wall of the second anode metal reflective layer is first passivated and protected to prevent the second anode metal reflective layer from being corroded or broken, which is beneficial for the obtained middle anode metal reflective layer to maintain good optical mirror properties, improve the light reflection efficiency, ensure the stability of the luminous brightness and uniformity of the OLED device, and avoid the local brightness reduction or uneven luminescence caused by sidewall corrosion; and, it can maintain stable electrical performance, ensure uniform current distribution, make the OLED light emission more stable and uniform, reduce device failures caused by changes in electrical performance, improve structural stability, and extend service life. In addition, the present invention adopts a step-by-step etching method (grabbing the end point of the etching signal), which can accurately control the etching of the first anode metal reflective layer, so that the obtained bottom anode metal reflective layer has a high taper angle, and improves the anti-reflection ability of the bottom anode metal reflective layer.

[0034] It should be noted that after the first etching, the third anode metal reflective layer is the top anode metal reflective layer described in the first aspect. After the second etching, the second anode metal reflective layer is the middle anode metal reflective layer described in the first aspect, and the third anode metal reflective layer is the bottom anode metal reflective layer described in the first aspect.

[0035] It should be noted that during the second etching process, the protective layer formed on the side wall of the second anode metal reflective layer will gradually react with the etching gas in the second etching process, so that after the entire anode structure is etched, the protective layer on the side wall has completely reacted, resulting in the absence of a protective layer on the side wall of the middle anode metal reflective layer in the final product structure.

[0036] Preferably, the substrate is a silicon-based substrate, for example, a silicon wafer.

[0037] Preferably, the first etching method comprises plasma enhanced chemical vapor deposition.

[0038] Preferably, during the first etching process, the first etching gas used includes chlorine and / or boron trichloride.

[0039] For example, if the first etching gas is only chlorine gas, the chemical reaction occurring during the first etching process is as follows:

[0040] (1)TiN+Cl2→TiCl4(g)+N2; (2)Al+Cl2→Al2Cl6(g).

[0041] Exemplarily, if the first etching gas includes chlorine and boron trichloride, the following reaction may occur for the third anode metal reflective layer: TiN+Cl2→TiCl4(g)+N2; and the following reaction may occur for the second anode metal reflective layer: Al+Cl / Cl2→Al Cl3(Al2Cl6)(g), and this process also forms boron trichloride cations (BCl3+), which can capture Cl, thereby reducing isotropic and lateral corrosion effects.

[0042] Preferably, the gas flow rate of the first etching gas is 100-200 sccm, for example, 100 sccm, 120 sccm, 140 sccm, 160 sccm, 180 sccm or 200 sccm.

[0043] Preferably, the etching temperature of the first etching is 60-80°C, for example, 60°C, 65°C, 70°C, 75°C or 80°C.

[0044] Preferably, the oxygen-containing gas comprises oxygen.

[0045] Preferably, the inert gas comprises nitrogen.

[0046] In the present invention, nitrogen and oxygen are introduced to cooperate with each other. The nitrogen acts as a protective gas, so that only a thin layer of the side wall of the second anode metal reflective layer is oxidized; secondly, it can prevent external water vapor, corrosive gases, etc. from directly contacting the surface of the second anode metal reflective layer, further reducing the risk of metal corrosion; finally, oxygen and the second anode metal reflective layer undergo a slight oxidation reaction to form a dense oxide film, and the presence of nitrogen can regulate the rate of this oxidation reaction so that it is not too intense.

[0047] Preferably, the flow rate of the oxygen-containing gas is 500-700 sccm, for example, 500 sccm, 550 sccm, 600 sccm, 650 sccm or 700 sccm, etc., preferably 500-600 sccm.

[0048] In the present invention, a proper amount of oxygen-containing gas undergoes a slight oxidation reaction with the side wall of the second anode metal reflective layer, which helps to form a dense oxide film, and this oxide film can play a protective role.

[0049] Preferably, the inert gas has an inlet flow rate of 300-400 sccm, for example, 300 sccm, 320 sccm, 340 sccm, 360 sccm, 380 sccm or 400 sccm.

[0050] Preferably, the ratio of the inlet flow rate of the oxygen-containing gas to the inlet flow rate of the inert gas is (500-700):(300-400).

[0051] In the present invention, the introduction of an appropriate amount of inert gas and an appropriate amount of oxygen-containing gas can accurately control the formation process and thickness of the oxide film, i.e., the protective layer, thereby obtaining an oxide film with optimal protective performance, thereby better protecting the second anode metal reflective layer.

[0052] Preferably, the passivation treatment method includes plasma enhanced chemical vapor deposition.

[0053] Preferably, during the passivation treatment, the radio frequency power of the oxygen-containing gas is 10-70 W, for example, 10 W, 20 W, 30 W, 40 W, 50 W, 60 W or 70 W, etc., preferably 30-40 W.

[0054] In the present invention, appropriate RF power of the oxygen-containing gas is beneficial to controlling the growth rate of the protective layer, ensuring the uniformity of the protective layer, and preventing the phenomenon of insufficient oxidation or excessive oxidation in some areas.

[0055] Preferably, during the passivation treatment, the RF power of the upper electrode of the inert gas is 1-2KW, for example, 1KW, 1.2KW, 1.4KW, 1.6KW, 1.8KW or 2KW, and the RF power of the lower electrode is 200-400W, for example, 200W, 250W, 300W, 350W or 400W.

[0056] In the present invention, the RF power of the upper electrode of the inert gas is adjusted to 1-2KW, so that the inert gas can be fully dissociated into plasma. At the same time, the RF power of the lower electrode of the inert gas is adjusted to 200-400W, which is beneficial to control the vertical movement of the inert gas for dissociation reaction and avoid anisotropy.

[0057] Preferably, the temperature of the passivation treatment is 100-250°C, for example, 100°C, 150°C, 200°C or 250°C, etc., preferably 150-200°C.

[0058] In the present invention, the passivation treatment is carried out at a suitable temperature, which is beneficial to controlling the oxidation reaction rate and allowing the oxidation reaction to proceed at a reasonable speed; secondly, the appropriate temperature helps the oxidation reaction to occur uniformly on the side wall of the second anode metal reflective layer, thereby improving the protection and use effects of the protective layer.

[0059] Preferably, the passivation treatment time is 0.5-3 h, for example, it can be 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h or 3 h, and is preferably 0.5-1.5 h.

[0060] Preferably, the material of the protective layer includes aluminum oxide.

[0061] Preferably, the width of the protective layer is greater than 5 nm, for example, it may be 6 nm, 7 nm, 8 nm, 9 nm, 10 nm or 15 nm, etc., preferably 8-10 nm.

[0062] It should be noted that the width direction of the protection layer is perpendicular to the thickness direction of the second anode metal reflective layer.

[0063] In the present invention, a protective layer that is too narrow may not be able to effectively block the subsequent second etching, and may be easily corroded to form grooves.

[0064] Preferably, the second etching method comprises plasma enhanced chemical vapor deposition.

[0065] Preferably, during the second etching process, the second etching gas used includes chlorine and / or boron trichloride.

[0066] Preferably, the gas flow rate of the second etching gas is 400-800 sccm, for example, 400 sccm, 500 sccm, 600 sccm, 700 sccm or 800 sccm.

[0067] In the present invention, the second etching gas is introduced at the above-mentioned gas flow rate to perform the second etching, which can effectively remove the first anode metal reflective layer at the bottom of the isolation area, and the taper angle formed is ≥75°, so that the anti-reflection ability of the final bottom anode metal reflective layer is enhanced.

[0068] Preferably, the etching temperature of the second etching is 60-80° C., for example, 60° C., 70° C. or 80° C., etc.

[0069] In a third aspect, the present invention provides a micro OLED display, wherein the micro OLED display comprises the OLED anode as described in the first aspect.

[0070] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0071] Compared with the prior art, the present invention has the following beneficial effects:

[0072] In the OLED anode provided by the present invention, the side wall of the middle anode metal reflective layer is steep and flat, showing a morphology that is not corroded by the etching gas, and the taper angle of the trapezoidal bottom anode metal reflective layer is ≥75°, indicating that the taper of the bottom anode metal reflective layer is further improved, which is beneficial to improving the Pixel aperture ratio of the OLED and obtaining excellent product efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] Figure 1 This is a schematic structural diagram of an OLED anode provided in Example 1 of the present invention.

[0074] Figure 2 This is a schematic diagram of the structure obtained by performing step (1) in the preparation method provided in Example 1 of the present invention.

[0075] Figure 3 This is a schematic diagram of the structure obtained by performing step (2) in the preparation method provided in Example 1 of the present invention.

[0076] Figure 4 This is a schematic diagram of the structure obtained by performing step (3) in the preparation method provided in Example 1 of the present invention.

[0077] Among them, 1-silicon-based substrate; 2-bottom anode metal reflective layer; 3-middle anode metal reflective layer; 4-top anode metal reflective layer; 5-transparent conductive layer; 2'-first anode metal reflective layer; 3'-second anode metal reflective layer; 4'-third anode metal reflective layer; 6-protective layer. DETAILED DESCRIPTION

[0078] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only used to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0079] Example 1

[0080] This embodiment provides an OLED anode, and its structural schematic diagram is as follows: Figure 1 As shown, the OLED anode includes a silicon-based substrate 1 and at least two OLED anode modules arranged on a surface of one side of the silicon-based substrate 1 and spaced apart from each other.

[0081] The OLED anode module includes a stacked bottom anode metal reflective layer 2, a middle anode metal reflective layer 3, a top anode metal reflective layer 4 and a transparent conductive layer 5 along a direction away from the silicon-based substrate; wherein the bottom anode metal reflective layer 2 and the top anode metal reflective layer 4 are both made of TiN, the middle anode metal reflective layer 3 is made of Al, and the transparent conductive layer 5 is made of ITO; the thickness of the bottom anode metal reflective layer 2 is 90nm, the thickness of the middle anode metal reflective layer 3 is 85nm, and the thickness of the top anode metal reflective layer 4 is 5nm.

[0082] The bottom anode metal reflective layer 2 has a trapezoidal shape with a taper angle of 80°; the side wall of the middle anode metal reflective layer 3 is steep and flat.

[0083] The top width of the bottom anode metal reflective layer 2 is smaller than the bottom width of the bottom anode metal reflective layer 2. The top surface of the bottom anode metal reflective layer 2 coincides with the bottom surface of the middle anode metal reflective layer 3, and the shortest distance between adjacent OLED anode modules is recorded as K, which is 0.8 μm.

[0084] The transparent conductive layer 5 has a trapezoidal shape, and the bottom surface of the transparent conductive layer 5 coincides with the top surface of the top anode metal reflective layer 4 .

[0085] This embodiment also provides a method for preparing the above-mentioned OLED anode, comprising the following steps:

[0086] (1) A silicon-based substrate is provided, on the surface of which a first anode metal reflective layer, a second anode metal reflective layer, a third anode metal reflective layer and a transparent conductive layer are stacked; wherein the transparent conductive layer is distributed on the top surface of the third anode metal reflective layer at intervals. The schematic diagram of the structure obtained in this step can be referred to Figure 2 .

[0087] (2) A plasma enhanced chemical vapor deposition method is used to perform a first etching on the third anode metal reflective layer and the second anode metal reflective layer between adjacent transparent conductive layers to form a partition area and expose the first anode metal reflective layer; wherein the first etching gas used in the first etching process is chlorine gas, the gas flow rate is 150 sccm, and the etching temperature is 70°C. The schematic diagram of the structure obtained in this step can be referred to Figure 3 .

[0088] (3) Passing oxygen gas with a flow rate of 600 sccm and nitrogen gas with a flow rate of 350 sccm, using plasma enhanced chemical vapor deposition to passivate the side wall of the second anode metal reflective layer after the first etching to form a protective layer, the material is aluminum oxide, the width is 8nm; wherein, the RF power of oxygen is 40W, the RF power of the upper electrode of nitrogen is 1.5KW, the RF power of the lower electrode is 300W, the temperature of the passivation treatment is 200°C, and the time of the passivation treatment is 2h. The schematic diagram of the structure obtained in this step can be found in Figure 4 .

[0089] (4) A plasma enhanced chemical vapor deposition method is used to perform a second etching on the first anode metal reflective layer at the bottom of the partition area to obtain an OLED anode; wherein the second etching gas used in the second etching process is chlorine gas, the gas flow rate is 600 sccm, and the etching temperature is 70°C.

[0090] Example 2

[0091] This embodiment provides an OLED anode, which includes a silicon-based substrate and at least two OLED anode modules arranged on a surface of one side of the silicon-based substrate and spaced apart from each other.

[0092] The OLED anode module includes a stacked bottom anode metal reflective layer, a middle anode metal reflective layer, a top anode metal reflective layer and a transparent conductive layer along a direction away from the silicon-based substrate; wherein the bottom anode metal reflective layer and the top anode metal reflective layer are both made of TiN, the middle anode metal reflective layer is made of Al, and the transparent conductive layer is made of ITO; the thickness of the bottom anode metal reflective layer is 80nm, the thickness of the middle anode metal reflective layer is 80nm, and the thickness of the top anode metal reflective layer is 3nm.

[0093] The bottom anode metal reflective layer has a trapezoidal morphology, and a taper angle of 75°; the side wall of the middle anode metal reflective layer is steep and flat.

[0094] The top width of the bottom anode metal reflective layer is smaller than the bottom width of the bottom anode metal reflective layer. The top surface of the bottom anode metal reflective layer coincides with the bottom surface of the middle anode metal reflective layer, and the shortest distance between adjacent OLED anode modules is recorded as K, which is 0.8 μm.

[0095] The transparent conductive layer has a trapezoidal morphology, and the bottom surface of the transparent conductive layer coincides with the top surface of the top anode metal reflective layer.

[0096] This embodiment also provides a method for preparing the above-mentioned OLED anode, comprising the following steps:

[0097] (1) A silicon-based substrate is provided, on the surface of which a first anode metal reflective layer, a second anode metal reflective layer, a third anode metal reflective layer and a transparent conductive layer are stacked; wherein the transparent conductive layer is distributed on the top surface of the third anode metal reflective layer at intervals.

[0098] (2) A plasma enhanced chemical vapor deposition method is used to perform a first etching on the third anode metal reflective layer and the second anode metal reflective layer between adjacent transparent conductive layers to form a partition area and expose the first anode metal reflective layer; wherein the first etching gas used in the first etching process is a combination of chlorine and boron trichloride, the gas flow rate is 200 sccm, and the etching temperature is 80°C.

[0099] (3) Oxygen gas with a flow rate of 500 sccm and nitrogen gas with a flow rate of 300 sccm are introduced, and the side wall of the second anode metal reflective layer after the first etching is passivated by plasma enhanced chemical vapor deposition to form a protective layer. The material is aluminum oxide with a width of 9 nm. Among them, the RF power of oxygen is 10 W, the RF power of the upper electrode of nitrogen is 1 KW, the RF power of the lower electrode is 200 W, the temperature of the passivation treatment is 100 ° C, and the time of the passivation treatment is 3 hours.

[0100] (4) A plasma enhanced chemical vapor deposition method is used to perform a second etching on the first anode metal reflective layer at the bottom of the partition area to obtain an OLED anode; wherein the second etching gas used in the second etching process is a combination of chlorine and boron trichloride, the gas flow rate is 800 sccm, and the etching temperature is 60°C.

[0101] Example 3

[0102] This embodiment provides an OLED anode, which includes a silicon-based substrate and at least two OLED anode modules arranged on a surface of one side of the silicon-based substrate and spaced apart from each other.

[0103] The OLED anode module includes a stacked bottom anode metal reflective layer, a middle anode metal reflective layer, a top anode metal reflective layer and a transparent conductive layer along a direction away from the silicon-based substrate; wherein the bottom anode metal reflective layer and the top anode metal reflective layer are both made of TiN, the middle anode metal reflective layer is made of Al, and the transparent conductive layer is made of ITO; the thickness of the bottom anode metal reflective layer is 100nm, the thickness of the middle anode metal reflective layer is 90nm, and the thickness of the top anode metal reflective layer is 8nm.

[0104] The bottom anode metal reflective layer has a trapezoidal morphology, and the taper angle is 85 degrees; the side wall of the middle anode metal reflective layer is steep and flat.

[0105] The top width of the bottom anode metal reflective layer is smaller than the bottom width of the bottom anode metal reflective layer. The top surface of the bottom anode metal reflective layer coincides with the bottom surface of the middle anode metal reflective layer, and the shortest distance between adjacent OLED anode modules is recorded as K, which is 0.8 μm.

[0106] The transparent conductive layer has a trapezoidal morphology, and the bottom surface of the transparent conductive layer coincides with the top surface of the top anode metal reflective layer.

[0107] This embodiment also provides a method for preparing the above-mentioned OLED anode, comprising the following steps:

[0108] (1) A silicon-based substrate is provided, on the surface of which a first anode metal reflective layer, a second anode metal reflective layer, a third anode metal reflective layer and a transparent conductive layer are stacked; wherein the transparent conductive layer is distributed on the top surface of the third anode metal reflective layer at intervals.

[0109] (2) A plasma enhanced chemical vapor deposition method is used to perform a first etching on the third anode metal reflective layer and the second anode metal reflective layer between adjacent transparent conductive layers to form a partition area and expose the first anode metal reflective layer; wherein the first etching gas used in the first etching process is chlorine gas, the gas flow rate is 100 sccm, and the etching temperature is 60°C.

[0110] (3) Oxygen gas with a flow rate of 700 sccm and nitrogen gas with a flow rate of 400 sccm are introduced, and the side wall of the second anode metal reflective layer after the first etching is passivated by plasma enhanced chemical vapor deposition to form a protective layer. The material is aluminum oxide with a width of 10 nm. Among them, the RF power of oxygen is 70 W, the RF power of the upper electrode of nitrogen is 2 KW, the RF power of the lower electrode is 400 W, the temperature of the passivation treatment is 250 ° C, and the time of the passivation treatment is 0.5 h.

[0111] (4) A plasma enhanced chemical vapor deposition method is used to perform a second etching on the first anode metal reflective layer at the bottom of the partition area to obtain an OLED anode; wherein the second etching gas used in the second etching process is chlorine gas, the gas flow rate is 400 sccm, and the etching temperature is 80°C.

[0112] Example 4

[0113] The difference between this embodiment and the first embodiment is that the shortest distance K between adjacent OLED anode modules is 0.5 μm.

[0114] The rest of the preparation methods and parameters were the same as those in Example 1.

[0115] Example 5

[0116] The difference between this embodiment and embodiment 1 is that the oxygen gas flow rate in step (3) is 400 sccm.

[0117] The rest of the preparation methods and parameters were the same as those in Example 1.

[0118] Example 6

[0119] The difference between this embodiment and embodiment 1 is that the oxygen gas flow rate in step (3) is 800 sccm.

[0120] The rest of the preparation methods and parameters were the same as those in Example 1.

[0121] Example 7

[0122] The difference between this embodiment and embodiment 1 is that the nitrogen flow rate in step (3) is 200 sccm.

[0123] The rest of the preparation methods and parameters were the same as those in Example 1.

[0124] Example 8

[0125] The difference between this embodiment and embodiment 1 is that the nitrogen gas flow rate in step (3) is 500 sccm.

[0126] The rest of the preparation methods and parameters were the same as those in Example 1.

[0127] Example 9

[0128] The difference between this embodiment and embodiment 1 is that the radio frequency power of oxygen in step (3) is 5W.

[0129] The rest of the preparation methods and parameters were the same as those in Example 1.

[0130] Example 10

[0131] The difference between this embodiment and embodiment 1 is that the radio frequency power of oxygen in step (3) is 75W.

[0132] The rest of the preparation methods and parameters were the same as those in Example 1.

[0133] Embodiment 11

[0134] The difference between this embodiment and embodiment 1 is that the RF power of the upper electrode and the RF power of the lower electrode of nitrogen in step (3) are the same, both of which are 300W.

[0135] The rest of the preparation methods and parameters were the same as those in Example 1.

[0136] Example 12

[0137] The difference between this embodiment and embodiment 1 is that the temperature of the passivation treatment in step (3) is 80°C.

[0138] The rest of the preparation methods and parameters were the same as those in Example 1.

[0139] Example 13

[0140] The difference between this embodiment and embodiment 1 is that the temperature of the passivation treatment in step (3) is 300°C.

[0141] The rest of the preparation methods and parameters were the same as those in Example 1.

[0142] Embodiment 14

[0143] The difference between this embodiment and embodiment 1 is that the width of the protective layer in step (3) is 3 nm.

[0144] The rest of the preparation methods and parameters were the same as those in Example 1.

[0145] Embodiment 15

[0146] The difference between this embodiment and embodiment 1 is that the gas flow rate of the second etching gas in step (4) is 300 sccm.

[0147] The rest of the preparation methods and parameters were the same as those in Example 1.

[0148] Comparative Example 1

[0149] The difference between this comparative example and Example 1 is that step (3) is not performed, that is, no protective layer is provided.

[0150] The rest of the preparation methods and parameters were the same as those in Example 1.

[0151] Comparative Example 2

[0152] The difference between this comparative example and Example 1 is that the nitrogen gas in step (3) is replaced by CHF3 gas.

[0153] The rest of the preparation methods and parameters were the same as those in Example 1.

[0154] Comparative Example 3

[0155] The difference between this comparative example and Example 1 is that a one-step etching method is adopted so that the taper angle of the bottom anode metal reflective layer is 40°.

[0156] The rest of the preparation methods and parameters were the same as those in Example 1.

[0157] Performance Testing

[0158] A micro OLED display was manufactured based on the OLED anodes provided in the above embodiments and comparative examples, and reliability tests, service life tests and pixel aperture ratio tests were performed.

[0159] Reliability test: The micro OLED display prepared above is subjected to the conditions of a specific temperature of 85°C and a humidity of 85%, and the device is observed to have any bad performance under different time periods of the double 85 conditions; the specific time can be: 240h, 350h, 504h, 672h.

[0160] Service life test: For the micro OLED display prepared above, the time required for the brightness to decay from 100% to 95% under a specific temperature (40° C.) and a specific monochrome image is used to characterize the service life.

[0161] Pixel aperture ratio test:

[0162] Place the OLED display on the measuring platform, observe the display through a microscope, select pixels at five different positions, and then collect pixel images. Use professional measurable irregular graphics software to analyze and measure the obtained pixel images, and then use the following formula to calculate the aperture ratio of each pixel: aperture ratio = (light-emitting area / entire pixel area) × 100%. Perform statistics on the calculated results, and then calculate the average value of the pixel aperture ratio.

[0163] The above test results are shown in Table 1.

[0164] Table 1

[0165]

[0166]

[0167] analyze:

[0168] It can be seen from the above table that in the OLED anode provided by the present invention, the side wall of the middle anode metal reflective layer is not corroded by the etching gas, and the taper angle of the trapezoidal bottom anode metal reflective layer is ≥75°, indicating that the taper of the bottom anode metal reflective layer is further improved, which is beneficial to improve the Pixel aperture ratio of the OLED and obtain excellent product efficiency.

[0169] It can be seen from the first and fourth embodiments that if the shortest distance K between adjacent OLED anode modules is too small, it is easy to cause the device to have bright spot defects.

[0170] It can be seen from Example 1 and Examples 5-6 that if the oxygen flow rate in step (3) is too small, it is impossible to provide enough oxygen atoms for the side wall of the second anode metal reflective layer to form a complete and dense protective layer, and it is impossible to effectively block the subsequent contact of the second etching gas, which is easy to produce grooves and affect the service life; if the oxygen flow rate in step (3) is too large, the reaction is too violent, which is easy to cause the side wall of the second anode metal reflective layer to form an overly thick and uneven oxide layer, resulting in problems such as loose protective layer structure and easy cracking, and effective protection cannot be achieved.

[0171] It can be seen from Example 1 and Examples 7-8 that if the nitrogen flow rate in step (3) is too small, the oxygen concentration cannot be effectively diluted, resulting in the side wall surface of the second anode metal reflective layer being in contact with too much oxygen, causing the oxidation reaction to be too intense, resulting in the formation of a thick, uneven and poor quality protective layer on the side wall surface, and the protection effect is poor; if the nitrogen flow rate in step (3) is too large, a large amount of nitrogen will dilute the oxygen concentration, resulting in too little contact between the side wall surface of the second anode metal reflective layer and oxygen, resulting in the oxidation reaction being difficult to fully proceed, thereby failing to form a protective layer of sufficient thickness and quality, and failing to effectively protect the second anode metal reflective layer.

[0172] It can be seen from Examples 1 and 9-10 that if the RF power of oxygen in step (3) is too small, the amount of oxygen plasma generated is small, the activity is low, the protective layer grows slowly, the production efficiency is low, and the cost is increased; if the RF power of oxygen in step (3) is too large, the reaction is too violent, the protective layer grows too fast, and it is difficult to accurately control its thickness and quality, which may cause the protective layer to be uneven or defective, affecting the service life of the device.

[0173] It can be seen from Example 1 and Example 11 that if the upper electrode RF power and the lower electrode RF power of nitrogen in step (3) are the same, the plasma formed by dissociation may diffuse laterally, and the effective plasma that actually acts on the second anode metal reflective layer becomes less, which is not conducive to the dissociated plasma and the side wall of the second anode metal reflective layer to form a denser passivation layer for protection.

[0174] It can be seen from Example 1 and Examples 12-13 that if the temperature of the passivation treatment is too low, the oxidation reaction rate is slow, which prolongs the production cycle, reduces production efficiency, and increases costs; if the temperature of the passivation treatment is too high, the reaction rate is too fast, and it is difficult to accurately control the growth of the protective layer, which may cause the thickness of the protective layer to not meet the requirements, or even cause problems such as over-oxidation, affecting device performance.

[0175] It can be seen from Examples 1 and 14-15 that if the width of the protective layer is too small, it may not be able to effectively block the erosion of the subsequent second etching gas, resulting in grooves on the side walls of the middle anode metal reflective layer, affecting the service life of the device; if the gas flow rate of the second etching gas is too small, it is not conducive to further improving the taper of the bottom anode metal reflective layer, resulting in a decrease in the Pixel opening rate of the OLED.

[0176] It can be seen from Example 1 and Comparative Example 1 that if no protective layer is provided, the side wall of the middle anode metal reflective layer will be corroded and grooves will appear, which will affect product performance and aperture ratio.

[0177] It can be seen from Example 1 and Comparative Example 2 that if nitrogen is replaced with CHF3 gas, that is, a combination of oxygen and CHF3 gas is used, then the dissociated F ions will have a serious corrosive effect on the second anode metal reflective layer, thereby causing irreversible damage to the second anode metal reflective layer, affecting the uniformity of light emission and reflection of high light, and thus failing to increase the Pixel aperture ratio of the OLED.

[0178] It can be seen from Example 1 and Comparative Example 3 that if the taper angle of the bottom anode metal reflective layer is 40°, it is not conducive to improving the Pixel aperture ratio of the OLED, and will indirectly affect the size between the bottom anode metal reflective layers between adjacent modules. If the product is limited by the design size, it is easy to lead to poor device performance.

[0179] The applicant declares that the present invention illustrates the process method of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned process steps, that is, it does not mean that the present invention must rely on the above-mentioned process steps to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the raw materials selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. An OLED anode, characterized in that: The OLED anode comprises a substrate and at least two OLED anode modules arranged on a surface of one side of the substrate and spaced apart from each other; The OLED anode module includes a bottom anode metal reflective layer, a middle anode metal reflective layer, a top anode metal reflective layer and a transparent conductive layer stacked in a direction away from the substrate; The bottom anode metal reflective layer has a trapezoidal shape, and a taper angle of ≥75°; the side wall of the middle anode metal reflective layer is steep and flat.

2. The OLED anode according to claim 1, characterized in that: The top surface of the bottom anode metal reflective layer overlaps with the bottom surface of the middle anode metal reflective layer, and the shortest distance between adjacent OLED anode modules is denoted as K, K≥0.6 μm.

3. The OLED anode according to claim 1 or 2, characterized in that: The materials of the bottom anode metal reflective layer and the top anode metal reflective layer independently include TiN and / or Ti; And / or, the material of the middle anode metal reflective layer includes Al; And / or, the material of the transparent conductive layer includes any one of ITO, FTO or IZO or a combination of at least two thereof; And / or, the transparent conductive layer has a trapezoidal morphology, and the bottom surface of the transparent conductive layer coincides with the top surface of the top anode metal reflective layer.

4. The OLED anode according to any one of claims 1 to 3, characterized in that: The thickness of the bottom anode metal reflective layer is 80-100nm; And / or, the thickness of the middle anode metal reflective layer is 80-90 nm; And / or, the thickness of the top anode metal reflective layer is 3-8 nm.

5. A method for preparing an OLED anode according to any one of claims 1 to 4, characterized in that: The preparation method comprises the following steps: Providing a substrate, on the surface of which a first anode metal reflective layer, a second anode metal reflective layer, a third anode metal reflective layer and a transparent conductive layer are stacked, and the transparent conductive layers are spaced and distributed on the top surface of the third anode metal reflective layer; Performing a first etching on the third anode metal reflective layer and the second anode metal reflective layer between adjacent transparent conductive layers to form a partition area and expose the first anode metal reflective layer; Oxygen-containing gas and inert gas are introduced to passivate the sidewalls of the second anode metal reflective layer after the first etching to form a protective layer, and then the first anode metal reflective layer at the bottom of the partition area is second etched to obtain the OLED anode.

6. The preparation method according to claim 5, characterized in that: The substrate is a silicon-based substrate; And / or, the first etching method includes plasma enhanced chemical vapor deposition; And / or, during the first etching process, the first etching gas used includes chlorine and / or boron trichloride; And / or, the gas flow rate of the first etching gas is 100-200 sccm; And / or, the etching temperature of the first etching is 60-80°C.

7. The preparation method according to claim 5 or 6, characterized in that: The oxygen-containing gas includes oxygen; and / or, the inert gas comprises nitrogen; And / or, the oxygen-containing gas has an inlet flow rate of 500-700 sccm, preferably 500-600 sccm; And / or, the inert gas has an inlet flow rate of 300-400 sccm.

8. The preparation method according to any one of claims 5 to 7, characterized in that: The passivation treatment method includes plasma enhanced chemical vapor deposition; And / or, during the passivation treatment, the radio frequency power of the oxygen-containing gas is 10-70W, preferably 30-40W; And / or, during the passivation treatment, the radio frequency power of the upper electrode of the inert gas is 1-2KW, and the radio frequency power of the lower electrode is 200-400W; And / or, the temperature of the passivation treatment is 100-250°C, preferably 150-200°C; And / or, the passivation treatment time is 0.5-3h, preferably 0.5-1.5h; And / or, the material of the protective layer includes aluminum oxide; And / or, the width of the protective layer is greater than 5 nm, preferably 8-10 nm.

9. The preparation method according to any one of claims 5 to 8, characterized in that: The second etching method includes plasma enhanced chemical vapor deposition; And / or, during the second etching process, the second etching gas used includes chlorine and / or boron trichloride; And / or, the gas flow rate of the second etching gas is 400-800 sccm; And / or, the etching temperature of the second etching is 60-80°C.

10. A micro OLED display, characterized in that: The micro OLED display comprises the OLED anode as claimed in any one of claims 1 to 4.

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