Display device

Abstract

The purpose of the present invention is to provide a display device in which adhesion between a color conversion layer and a partition wall is improved. This display device is characterized in having a light emitting element provided on a substrate, a partition wall formed around the light emitting element, and a color conversion layer filling an opening space of the partition wall, wherein a plurality of projection parts is formed on a side wall surface of the partition wall. In the present invention, it is preferable that the side wall surface comprises a mixture of a rough surface appearing as vertical streaks and the projection parts.

Description

Display device

[0001] The present invention relates to a display device.

[0002] Patent document 1 discloses an invention relating to a display device that includes a light-emitting element layer and a light control unit arranged on the light-emitting element layer, and that has a partition wall provided to prevent the light emitted from the multiple light control units from mixing together.

[0003] Patent Document 2 discloses an invention relating to a micro LED display device including a micro LED array substrate, partitions that separate the micro LEDs, and a wavelength conversion layer that fills the partitions.

[0004] JP 2020-184540 A JP 2020-205417 A

[0005] None of the patent documents discloses a method for preventing color mixing between pixels, and there is no mention of adhesion between the color conversion layer (wavelength conversion layer) and the partition wall.

[0006] The present invention has been made in view of the above points, and has an object to provide a display device in which the adhesion between the color conversion layer and the partition walls is improved.

[0007] One aspect of the display device of the present invention is characterized in that it comprises a light-emitting element provided on a substrate, a partition formed around the light-emitting element, and a color conversion layer filling an opening space of the partition, and a protrusion portion is formed on a side wall surface of the partition.

[0008] According to the display device of the present invention, by forming the protrusions on the sidewall surfaces, it is possible to improve the adhesion between the color conversion layer and the partition walls, and to suppress the occurrence of voids.

[0009] FIG. 1 is a cross-sectional schematic diagram of a micro LED display as a display device according to the present embodiment. FIG. 2A is a partial front view showing the sidewall surface of a partition wall, and FIG. 2B is a plan view of the partition wall. FIG. 3A is an SEM photograph of an experimental example in which protrusions are formed on the sidewall surface of a partition wall. FIG. 3B is an enlarged view of a portion of the SEM photograph of FIG. 3A showing measurement points for calculating the height ratio. FIG. 3C is a schematic view of FIG. 3B. FIG. 3D is a view of the SEM photograph of FIG. 3A showing the height dimension. FIG. 4A is an SEM photograph of a plurality of partition walls in a plan view. FIG. 4B is an enlarged SEM photograph of an arbitrarily selected partition wall from FIG. 4A showing measurement points for measuring the groove depth between each protrusion. FIG. 4C is a schematic view of FIG. 4B. FIG. 5 is a partial cross-sectional schematic diagram of a display device for explaining the conventional problems. FIG. 5 is a process diagram for explaining a method for forming partition walls constituting the display device according to the present embodiment. FIG. 5 is a process diagram for explaining a method for forming partition walls constituting the display device according to the present embodiment. 1A to 1C are diagrams illustrating a process for explaining a method for forming partition walls that constitute the display device of the present embodiment.

[0010] The following describes in detail an embodiment of the present invention, but the following description is an example (typical example) of the embodiment of the present description, and the present invention is not limited to these details as long as it does not deviate from the gist of the present invention. Furthermore, the notation "to" used below includes both the lower limit and the upper limit within the range.

[0011] <Background to the Invention of the Display Device of the Present Embodiment> Liquid crystal on silicon (LCOS), laser beam scanning (LBS), or organic light-emitting diode (OLED) microdisplays are currently mainstream for use in head-mounted displays for AR (Augmented Reality) / MR (Mixed Reality). However, these methods do not provide sufficient brightness in external light, and are therefore primarily used indoors.

[0012] In contrast, the micro LED method is considered to be more advantageous than the above methods in terms of brightness, and is expected to see expanded application in the future.

[0013] As a method for displaying full color using a micro LED display, a technology has been proposed in which blue light-emitting elements are used as light-emitting elements (LEDs), and color conversion (wavelength conversion) is performed using a color conversion layer to enable RGB display.

[0014] Furthermore, in order to suppress color mixing between pixels, Japanese Patent Application Laid-Open Nos. 2003-222299 and 2003-222299 propose a structure in which partition walls are provided to separate pixels.

[0015] The partition walls are arranged around the light-emitting elements. Therefore, the light-emitting elements are open above the partition walls, and the color conversion layer fills the open spaces in the partition walls. The color conversion layer contains fluorescent particles such as quantum dots, but these fluorescent particles are often made of materials with low heat resistance, and quantum dots generally have low heat resistance. Therefore, it was found that high temperatures cannot be applied to harden the color conversion layer, and appropriate thermal contraction stress is not applied, resulting in reduced adhesion to the partition walls.

[0016] Figure 5 is a partial cross-sectional schematic diagram of a display device to explain the problems of the related art. Color filters and microlenses are omitted in Figure 5. As shown in Figure 5, voids 32 were generated due to insufficient adhesion between the partition walls 30 and the color conversion layer 31. Because the voids 32 are air spaces, no quantum dots exist there, and due to diffuse reflection by the voids 32, part of the excitation light from the light-emitting element is not properly color converted, resulting in a decrease in color conversion efficiency and a decrease in brightness.

[0017] Therefore, as a result of intensive research, the inventors have invented a display device in which the surface area is increased by forming protrusions on the side wall surfaces of the partition walls, thereby improving the adhesion between the color conversion layer and the partition walls.

[0018] <Description of Display Device of the Present Embodiment> The display device of the present embodiment is configured as a micro LED (Light Emitting Diode) display 1 shown in Fig. 1. Fig. 1 is a schematic cross-sectional view of the micro LED display 1.

[0019] As shown in Fig. 1, the micro LED display 1 includes a plurality of display pixels 2a, 2b, and 2c. For example, the display pixel 2a shown in Fig. 1 is a red display pixel, the display pixel 2b is a green display pixel, and the display pixel 2c is a blue display pixel.

[0020] 1, a plurality of light-emitting elements 4 are arranged on a substrate 3. For example, the light-emitting elements 4 are arranged in a matrix on the substrate 3. Each light-emitting element 4 is a blue-emitting micro LED.

[0021] 1 , partition walls 5 are formed on the substrate 3 to separate the light-emitting elements 4. The partition walls 5 are formed so as to surround the outer periphery of each light-emitting element 4 in a plan view, and are open above the light-emitting elements 4. In the present embodiment, the material of the partition walls 5 is not limited, but the partition walls 5 may be formed, for example, from a material containing a white pigment or a black pigment, or from a mixed material containing purple, blue, yellow, red, or other pigments, or from an infrared-transmitting material, or may have a reflective film such as a metal formed on the sidewall surface of the partition walls 5.

[0022] 1, color conversion layers 6a and 6b are filled in the opening spaces 5c extending from the sidewall surfaces 5a of the partition walls 5 of the red-displaying pixels 2a and the green-displaying pixels 2b to the openings 5b. As shown in Fig. 1, the color conversion layers have red quantum dots 7 and green quantum dots 8 dispersed in the red-displaying pixels 2a and the green-displaying pixels 2b, respectively. The color conversion layers 6a and 6b are in close contact with the light-emitting elements 4 and the sidewall surfaces 5a of the partition walls 5.

[0023] The quantum dots 7 and 8 are dispersed in a resin 9. The resin 9 is preferably a transparent resin. There are no limitations on the material of the resin 9, but examples thereof include acrylic resins, polyurethane resins, polyester resins, polyolefin resins, polycarbonate resins, polyethyleneimine resins, epoxy resins, and thioether resins.

[0024] The red quantum dots 7 preferably have a fluorescence peak wavelength of 600 nm to 680 nm, and the green quantum dots 8 preferably have a fluorescence peak wavelength of 520 nm to 560 nm. These quantum dots 7 and 8 absorb blue light as excitation light irradiated from the light-emitting element 4, and emit red or green light after color conversion.

[0025] Although the materials are not limited, because cadmium (Cd) is toxic and its use is restricted in various countries, the quantum dots 7 and 8 are preferably cadmium-free. Furthermore, the quantum dots 7 and 8 preferably have a core-shell structure including a core and a shell covering the core, such as ZnSe / ZnS, ZnSe / ZnSeS, ZnTe / ZnS, ZnSeTe / ZnS, or InP / ZnS. However, the quantum dots 7 and 8 may be composed of only a core. Furthermore, to improve dispersibility, the quantum dots 7 and 8 preferably have a ligand (organic ligand) on their surfaces.

[0026] The particle size of the quantum dots 7 and 8 is several nanometers to several tens of nanometers. The fluorescence peak wavelength can be controlled by adjusting the particle size and composition. Note that the color conversion layers 6 a and 6 b may contain phosphors other than the quantum dots 7 and 8.

[0027] On the other hand, as shown in FIG. 1 , the open space 5c of the partition wall 5 of the blue display pixel 2c is filled with resin 9, but does not contain quantum dots. The resin 9 is preferably a transparent resin. "Transparent" means that the visible light transmittance is 50% or more, preferably 70% or more, and most preferably 90% or more. The visible light transmittance can be measured in accordance with JIS K 7375:2008.

[0028] The color conversion layers 6 a, 6 b may contain fluorescent particles other than the quantum dots, together with or instead of the quantum dots 7, 8. However, in this embodiment, it is preferable to use the quantum dots 7, 8 in order to obtain excellent color purity.

[0029] 1, the surfaces of the color conversion layers 6a, 6b and resin 9 may be formed at substantially the same height as the partition walls 5, or may be slightly lower than the partition walls 5. The thickness of the color conversion layers 6a, 6b is about 2 to 10 μm.

[0030] 1, a color filter 11 is provided on the surfaces of the color conversion layers 6a, 6b and the resin 9 via a barrier layer 10. The color filter 11 includes a red color filter 11a, a green color filter 11b, and a blue color filter 11c. The thickness of the color filter 11 is not limited, but is, for example, about 0.5 μm to 2.0 μm.

[0031] Although the barrier layer 10 is not an essential layer, providing the barrier layer 10 can reduce the thermal influence on the quantum dots 7 and 8 in the color conversion layers 6a and 6b when the color filter 11 is formed, and also has the function of protecting the quantum dots 7 and 8 from air and moisture. Furthermore, if there are irregularities between the surfaces of the partition wall 5 and the color conversion layers 6a and 6b and the resin 9, the barrier layer 10 can smooth out the irregularities. This allows the color filter 11 to be formed on a flat surface. There are no restrictions on the material of the barrier layer 10, but it is preferably an oxide film or a nitride film, for example, SiO ２ The thickness of the barrier layer 10 is not limited, but is about 50 nm to 1 μm.

[0032] Alternatively, a resin layer may be formed on the surfaces of the color conversion layers 6 a, 6 b and the resin 9, and the barrier layer 10 may be formed thereon. This can promote planarization and further improve the protective function of protecting the quantum dots 7, 8 from air and moisture.

[0033] 1, microlenses 12a to 12c can be provided on the surface of the color filter 11. The microlenses 12a to 12c are optically transparent. Although not limited thereto, the microlenses 12a to 12c can be made of organic materials such as acrylic resin, epoxy resin, and silicon resin, or SiN, SiO ２As shown in FIG. 1, the microlenses 12a to 12c are convex lenses, but they can also be concave lenses. The surface shapes of the microlenses 12a to 12c can be changed in various ways depending on the relationship between the refractive index and the layer located on the surface of the microlenses 12a to 12c. The microlenses 12a to 12c may also be metalenses. A metalense is a flat lens in which nanostructures are arranged two-dimensionally, and optical properties such as light collection can be controlled by adjusting the shape, spacing, height, etc. of the nanostructures. Although not limited thereto, metalenses can be made of resin, metal, Si, SiO, etc. according to the target wavelength. ２ , SiN, or the like.

[0034] <Characteristic Configuration of the Micro LED Display 1 of the Present Embodiment> The micro LED display 1 of the present embodiment has the following characteristics: That is, as shown in Fig. 1 , a protrusion 13 is formed on the side wall surface 5a of the partition wall 5.

[0035] The formation of protrusions 13 can increase the surface area of ​​sidewall surface 5a, making it easier to obtain an anchor effect, and even if the heating temperature for curing color conversion layers 6a, 6b is low and the crosslinking density of color conversion layers 6a, 6b is insufficient, it is possible to improve adhesion between color conversion layers 6a, 6b and partition wall 5.

[0036] The configuration of the side wall surface of the partition wall in this embodiment will be described with reference to Fig. 2. As shown in Fig. 2A and Fig. 2B, the side wall surface 5a has a mixture of a rough surface appearing as vertical streaks 14 and protrusions 13. Here, the vertical streaks 14 are a finely uneven surface in which many stripe-like lines appear in the height direction of the side wall surface 5a in the circumferential direction of the side wall surface 5a.

[0037] As shown in Fig. 2A, the protrusions 13 are ridges that protrude higher than the surfaces of the vertical reinforcement 14 and are discontinued midway in the height direction. Therefore, the vertical reinforcement 14 is visible on the side wall surface 5a from midway up in the height direction. As shown in Fig. 2A, the height of each protrusion 13 is not approximately uniform but varies. The variation in height can be expressed as a variation σ in the height ratio, which will be described later.

[0038] 3A is an SEM photograph of the side wall surface of the partition wall, and it was confirmed that protrusions and vertical streaks were formed on the side wall surface. The protrusions protrude above the surface of the vertical streaks and their length is interrupted midway in the height direction, so the protrusions and vertical streaks can be distinguished on the SEM photograph. Alternatively, the step dimension (groove depth) of the protrusions is larger than the roughness dimension (surface roughness: can be expressed by arithmetic mean roughness Ra) of the vertical streaks, so the protrusions and vertical streaks can also be distinguished by the magnitude of roughness.

[0039] For example, the surface roughness of the vertical stripes formed on the sidewall surface of the partition wall and the step size of the protrusions can be calculated using SEM images or an atomic force microscope. The scanning microscope may be an SU3500 manufactured by Hitachi High-Technologies Corporation, or the atomic force microscope may be an NX20 manufactured by Park Systems Co., Ltd.

[0040] In this embodiment, the height ratio (H2 / H1) was calculated, where H1 is the barrier rib height and H2 is the protrusion height, and the variation σ (standard deviation) was determined. The method for determining the variation σ will be described below.

[0041] As shown in Figure 3B (an enlarged portion of the SEM photograph of Figure 3A) and its schematic diagram in Figure 3C, of ​​the multiple protrusions, the top five protrusions ((1) to (5)) with the highest height positions and the bottom five protrusions ((6) to (10)) with the lowest height positions are selected. Here, the number of protrusions used for the variation σ is not limited, but if the number is too small, the accuracy of the variation σ decreases, while if the number is too large, the accuracy of the variation σ increases but the analysis takes a long time. Therefore, it is desirable that the number of each of the top and bottom protrusions be in the range of about 3 to 10 as a practical range.

[0042] Then, the height ratio (H2 / H1) of each of the selected 10 protrusions is calculated. Here, the partition wall height H1 can be calculated as the height from the bottom end (the end facing the substrate 3) of the partition wall 5 to the opening at the top, as shown in FIG. 3D (the SEM photograph of FIG. 3A with the height dimensions clearly indicated). The protrusion height H2 can be calculated as the height from the bottom end of the partition wall 5 to the top end of the protrusion, as shown in FIG. 3D. Note that H2 shown in FIG. 3D indicates one protrusion height among the 10 measurement points. The top end of the protrusion is the highest point where it contacts the side wall surface (or vertical stripe).

[0043] 1, 3A, and 3D, the side wall surfaces 5a of the partition walls 5 are inclined, but the partition wall height H1 and the protrusion height H2 can be determined from the front image appearing in the SEM photograph shown in Fig. 3D. The side wall surfaces of the partition walls may be inclined or may be substantially vertical.

[0044] The variation σ (standard deviation) is then calculated from the height ratio (H2 / H1) of each of the 10 protrusions. In this embodiment, the variation σ is preferably 0.01 or more and 0.50 or less. This improves adhesion between the color conversion layer filling the opening spaces of the partition walls and the partition walls. The color conversion layer is formed by filling the opening spaces of the partition walls with a color conversion material containing quantum dots and curing it through heat treatment. The heat treatment temperature is low (specifically, 150°C or less) to prevent deterioration of the quantum dots. Conventionally, insufficient thermal contraction stress has led to the problem of voids 32, as shown in FIG. 5 . However, in this embodiment, by forming multiple protrusions 13 on the side wall surface 5a of the partition walls 5, the surface area can be increased, and the anchor effect can improve adhesion between the color conversion layers 6a, 6b and the partition walls 5, effectively suppressing the occurrence of voids 32. In the blue-display pixel 2c shown in FIG. 1, only the resin 9 is filled. However, in the process of simultaneously heating and hardening the color conversion layers of each pixel, a void 32 also occurs in the blue-display pixel 2c. Therefore, it is preferable to form a protrusion 13 on the side wall surface 5a of the partition wall 5 in the blue-display pixel 2c as well.

[0045] In this embodiment, the variation σ is more preferably 0.05 or more and 0.40 or less, which makes it possible to obtain good light collection properties as well as good adhesion.

[0046] The light-collecting ability can be determined, for example, by ray tracing (using LightTools software from Synopsys), and in this embodiment, a light extraction efficiency (light intensity ratio relative to excitation light) of 80% or more can be obtained.

[0047] In this embodiment, the variation σ is more preferably 0.18 or more and 0.30 or less. This makes it possible to more effectively improve both the adhesion and the light collection ability. Regarding the light collection ability, a light extraction efficiency of 90% or more can be obtained.

[0048] In order to obtain good light collection performance, it is preferable that the variation σ is small. That is, by reducing the variation σ, diffused reflection on the side wall surface 5 a can be suppressed, and the light extraction efficiency can be improved. However, if the variation σ is too small, adhesion will be somewhat reduced. For this reason, it is better for the heights of the protrusions 13 to vary moderately.

[0049] In this embodiment, the width T1 of the protrusion 13 is preferably 0.10 μm or more and 0.50 μm or less. The width T1 is more preferably 0.15 μm or more and 0.30 μm or less. The width T1 is defined as the length in the circumferential direction of the protrusion 13, or in the case of FIG. 2A, the length in the lateral direction of the page. The width T1 of the protrusion 13 can be calculated from the average value of the widths T1 of a plurality of protrusions 13.

[0050] 2A , adjacent protrusions 13 may be grouped together to form a protrusion 13a having a width dimension T1 that is wider than the other protrusions 13. The heights of the adjacent protrusions 13a are approximately the same, and the protrusions 13 can be recognized as a single protrusion 13.

[0051] By adjusting the width dimension T1 of the protrusions 13, it is possible to effectively increase the surface area, further improve adhesion, and obtain good light collection. If the width dimension T1 is too large, the effect of increasing the surface area is small, and if the width dimension T1 is too small, diffused reflection on the side wall surface 5a is likely to increase. Therefore, in order to obtain better adhesion and light collection, it is desirable to form the protrusions 13 with approximately the width dimension described above.

[0052] In addition, in this embodiment, the anchoring effect is enhanced and adhesion can be improved by mixing the vertical striations 14 as a rough surface formed on the side wall surface 5a with the protrusions 13. That is, a part of the resin 9 penetrates into the vertical striations 14, and not only does it provide the protrusions 13, but the mixture with the vertical striations 14 can more effectively improve adhesion.

[0053] In this embodiment, the protrusion height of protrusions 13 in plan view A from a direction perpendicular to substrate 3 is preferably 0.05 μm or more and 1.00 μm or less, and more preferably 0.10 μm or more and 0.50 μm or less. "Plan view A" refers to the direction directly below the surface of substrate 3, as shown in FIG. 1 . By having the protrusion height of this embodiment, a more preferable anchor effect can be obtained, and it is possible to further improve the adhesion between color conversion layers 6 a, 6 b and partition walls 5.

[0054] The protrusion height can be measured, for example, as follows. Fig. 4A is an SEM photograph of a plurality of partition walls in a plan view. Fig. 4A shows a peripheral area including the partition walls to be measured when measuring the above-mentioned variation σ. Fig. 4B is an enlarged SEM photograph of a partition wall arbitrarily selected from the plurality of partition walls shown in Fig. 4A. Fig. 4C is a schematic diagram of Fig. 4B.

[0055] As shown in the SEM photograph of FIG. 4B and the schematic diagram of FIG. 4C, the surface (exposed surface) of the substrate 3 exposed from the open space 5c can be confirmed.

[0056] 4B and 4C, a light-colored portion 15 is seen around the open space 5c and the exposed surface of the substrate 3. This portion 15 indicates an inclined surface formed on the side wall surface 5a of the partition wall 5.

[0057] As shown in FIGS. 4B and 4C, in plan view, the boundary line L1 between the light-colored portion 15 and the exposed surface of the substrate 3 appears as a concave-convex line.

[0058] 4B and 4C, for example, the boundary line L1 appearing around the exposed surface of the substrate 3 is recognized as having four sides, and for each boundary line L1 in the plan view of Figures 4B and 4C, a vertex P is determined that is farthest from the center C of the exposed surface of the substrate 3. Note that, although four sides are recognized in this experimental example, other than four sides may also be used, and in such cases, the vertex P of each side is determined.

[0059] As shown in Figures 4B and 4C, a reference line L2 is drawn connecting the four sides so as to pass through each vertex P. Then, in the plan view shown in Figures 4B and 4C, the lengths (protrusion heights) of, for example, any three points ((11) to (13)) from the reference line L2 to a boundary line L1 that protrudes toward the center C of the exposed surface of the substrate 3 for each side are measured. The protrusion heights of the protrusions 13 can then be averaged for a total of 12 points obtained by measuring three points on each side. There is no limitation on the number of protrusion height measurements, but they can be approximately 2 to 10 points on each side.

[0060] In the measurement of the protrusion height of the protrusion portion 13 shown in Figures 4A to 4C, the resin 9 is not filled in the opening space 5c of the partition wall 5 on the substrate 3. However, even if the resin 9 is filled, the boundary line L1 can be confirmed, or the boundary line L1 can be estimated or predicted, and the protrusion height of the protrusion portion 13 can be measured, or the protrusion height of the protrusion portion 13 can be estimated or predicted.

[0061] 6, a plurality of light-emitting elements 4 are formed on a substrate 3. The plurality of light-emitting elements 4 constitute an RGB pixel region.

[0062] Next, a partition wall material layer 22 is formed over the entire surface of the substrate 3. The partition wall material is not limited, and for example, a material containing a white pigment or a black pigment, or a partition wall material containing a mixed material containing purple, blue, yellow, or other pigments can be used. After applying the partition wall material layer 22, a heat treatment is performed. The heat treatment temperature is not limited, but is 250° C. or less. The heat treatment time is approximately several minutes to several tens of minutes.

[0063] Next, as shown in FIG. 6 , a resist layer 23 is applied to the upper surface 22 a of the partition wall material layer 22. A known material can be selected for the resist layer 23. As shown in FIG. 6 , a mask 24 is placed above the resist layer 23. The mask 24 has light-transmitting portions 24 a and non-transmitting portions 24 b. If the resist layer 23 is a positive type, the unexposed portions remain, whereas if the resist layer 23 is a negative type, the exposed portions remain. The patterns of the light-transmitting portions 24 a and non-transmitting portions 24 b of the mask 24 are changed depending on the type of resist layer 23. The mask 24 has a planar pattern of the partition walls 5. The resist layer 23 is exposed through the mask 24 and developed to form a resist pattern 23 a shown in FIG. 7 on the upper surface 22 a of the partition wall material layer 22.

[0064] Then, the partition material layer 22 not covered with the resist pattern 23a is removed by dry etching, and then the resist pattern 23a is removed (see FIG. 8). By anisotropic etching using dry etching, the sidewall surfaces 5a of the partition 5 can be formed as substantially vertical or inclined surfaces.

[0065] For dry etching, existing methods such as reactive ion etching and reactive gas etching can be used. Although the dry etching conditions are not limited, the etching gas is preferably CHF ３ , C.F. ４ , F ２ , HBr, Ar, O ２ A mixed gas of two or more kinds was used based on the above factors. As dry etching conditions, the flow rate of each gas was adjusted within the range of several sccm to 300 sccm.

[0066] In this embodiment, for example, O ２It was found that by adjusting the mixture ratio of the gas and Ar gas, the protrusions 13 can be formed and the variation σ can be adjusted to fall within a predetermined range.

[0067] Specifically, O ２ It is preferable that the O / Ar mixture ratio (percentage) is greater than 0% and equal to or less than 40%. ２ When the O / Ar mixture ratio is increased, the variation σ tends to be smaller. ２ It is more preferable that the CF / Ar mixture ratio is 0.1% or more and 30% or less. ４ No gas may be used.

[0068] Other etching conditions, such as the platen LF of the high frequency power supply, the inner coil HF, the outer coil HF, the frequency and duty of the pulse generator, and the pressure of the APC, can be set to conditions that have been generally used in the past.

[0069] The present invention will be described in detail below with reference to examples carried out to clarify the effects of the present invention, but the present invention is not limited to the following examples.

[0070] <Regarding Etching Conditions> In the experiment, a plurality of samples were manufactured by changing the etching conditions when forming partition walls by dry etching on a substrate provided with light-emitting elements. PEGASUS manufactured by Sumitomo Precision Products Co., Ltd. was used as the etching device. In Experimental Examples 1 and 2, O ２ / CF ４ In Experimental Examples 3 to 9, the gas flow rate ratio was adjusted. ２ The gas flow rate ratio of Ar to Ar was adjusted in the range of approximately 0.1% to 40%. Other manufacturing conditions for the high-frequency power source, pulse generator, and pressure control (APC) were the same for each experimental example. The sidewall surfaces of the partition walls were observed with a scanning electron microscope (SU3500, manufactured by Hitachi High-Tech).

[0071] <Method of calculating variation σ> The calculation of the variation σ in the height ratio (H2 / H1) is as explained using FIGS. 3B to 3D. That is, the partition height H1 was calculated, and the protrusion height H2 was also calculated. The protrusions used to calculate the variation σ were selected from the top five protrusions with the highest height positions and the bottom five protrusions with the lowest height positions. Then, the variation σ (standard deviation) was calculated from the height ratio (H2 / H1) of each of the 10 protrusions.

[0072] <Method for calculating the protrusion height of the protrusion> The calculation of the protrusion height of the protrusion in plan view is as explained using Figures 4A to 4C. That is, in plan view, the boundary between the substrate and the side wall surface was identified, and the vertex P furthest from the center of the substrate on the boundary line L1 was determined on four sides. Then, a reference line L2 connecting the four sides was drawn so as to pass through each vertex P, and the lengths (protrusion heights) of any three points on each side protruding from the reference line L2 to the boundary line L1 were measured. The protrusion heights of a total of 12 points were then averaged to determine the protrusion height of the protrusion.

[0073] <Measurement of Optical Properties> The shape of the sidewall surface of each sample was incorporated into a simulation model, and the light intensity rate (light collecting ability) for the excitation light was determined as an optical property.

[0074] The simulation conditions were as follows: Software: LightTools manufactured by Synopsys Method: Ray tracing method Materials of each structure Color conversion material: refractive index n=1.6 Partition wall: absorptance (for all light)=70% The experimental results are shown in Table 1.

[0075]

[0076] As shown in Table 1, in Experimental Examples 1 and 2, voids were observed, and adhesion between the partition walls and the color conversion layer was poor. In Experimental Examples 3 and 4, fine gaps were observed, but voids of the same size as in Experimental Examples 1 and 2 were not observed, demonstrating that the material is practical. In Experimental Examples 5 to 9, no voids were observed, demonstrating that good adhesion was maintained.

[0077] A light intensity rate of 80% or more was obtained in all of Experimental Examples 1 to 9. Of these, a light intensity rate of 90% or more was obtained in Experimental Examples 1 to 7.

[0078] Based on the experimental results, Experimental Examples 3 to 9 were designated as working examples, and Experimental Examples 1 and 2 were designated as comparative examples. In Experimental Example 1, no vertical streaks or protrusions were observed on the side wall surface, and in Experimental Example 2, no protrusions were formed on the side wall surface.

[0079] On the other hand, it was found that protrusions were formed on the sidewall surfaces in Experimental Examples 3 to 9. From the experimental results, a preferred range of the variation σ in height ratio, which provides good adhesion and light collection performance, was set to 0.01 or more and 0.50 or less, a more preferred range of the variation σ was set to 0.05 or more and 0.40 or less, and an even more preferred range of the variation σ was set to 0.18 or more and 0.30 or less.

[0080] Furthermore, the width of the protrusions was 0.15 μm or more and 0.30 μm or less in Experimental Examples 3 to 9. The width of the protrusions was determined from the average value of the widths of the protrusions used to calculate the variation σ.

[0081] In addition, in Experimental Examples 3 to 9, the protrusion height (average value) of the protrusions was 0.10 μm or more and 0.50 μm or less in plan view.

[0082] This application is based on Japanese Patent Application No. 2024-095228, filed on June 12, 2024, the contents of which are incorporated herein in their entirety.

Claims

1. A display device comprising: a light-emitting element provided on a substrate; a partition formed around the light-emitting element; and a color conversion layer filling an open space in the partition, wherein a plurality of protrusions are formed on a side wall surface of the partition.

2. The display device according to claim 1, wherein the side wall surface has a mixture of rough surfaces appearing as vertical stripes and the protrusions.

3. The display device according to claim 2, wherein the protrusion is a ridge extending partway up the height of the side wall surface, and the vertical stripe appears on the side wall surface from this point onward.

4. The display device according to claim 1, wherein the variation σ of the height ratio (H2 / H1), where H1 is the barrier rib height and H2 is the protrusion height, is 0.01 or more and 0.50 or less.

5. The display device according to claim 4, wherein the variation σ is equal to or greater than 0.05 and equal to or less than 0.

40.

6. The display device according to claim 4, wherein the variation σ is equal to or greater than 0.18 and equal to or less than 0.

30.

7. The display device according to claim 1, wherein the width of the protrusion is 0.10 μm or more and 0.50 μm or less.

8. The display device according to claim 1, wherein the protrusion height of the protrusions is 0.05 μm or more and 1.00 μm or less in plan view from a direction perpendicular to the substrate.

9. The display device according to claim 1, wherein the color conversion layer contains quantum dots.

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