Display chip based on monochromatic color conversion, and preparation method therefor

Abstract

The present invention relates to a display chip based on monochromatic color conversion, and a preparation method therefor. The display chip comprises a driving wafer, pixel units and a color conversion layer, wherein the driving wafer comprises anode contacts; the pixel units are arranged on the driving wafer and correspond to the anode contacts; each pixel unit comprises a P-type semiconductor layer, an active layer and an N-type semiconductor layer, which are sequentially arranged in a first direction, the P-type semiconductor layer is electrically connected to the corresponding anode contact on the driving wafer, and the N-type semiconductor layer is electrically connected to a cathode member; and the color conversion layer covers all the pixel units and is continuously arranged, and the top surface and at least part of the side surface of each pixel unit are both located inside the color conversion layer. Further disclosed in the present invention is a preparation method for a display chip. The present invention facilitates processing and achieves a simpler overall structure, can not only effectively avoid the problems of light leakage and low efficiency during color conversion, but also effectively enhances the fixing reliability and stability of a color conversion layer, such that the display quality of a chip is ensured.

Description

Display chip based on single-color color conversion and preparation method thereof

[0001] Priority information: This application claims priority to Chinese patent application No. 2024107890402, filed on June 19, 2024, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to the technical field of semiconductor technology, in particular to a display chip based on single-color color conversion and a preparation method thereof. BACKGROUND

[0003] Micro-LED (Micro Light Emitting Diode) is also known as micro light emitting diode. The Micro-LED display chip has a high-density pixel array, and each pixel unit in the pixel array can emit light independently. Each pixel unit of the Micro-LED display chip can usually only emit light of one color, so the Micro-LED display panel is usually a single-color panel, such as a red light panel that can only emit red light, a green light panel that can only emit green light, or a blue light panel that can only emit blue light, etc. With the continuous improvement of people's imaging requirements, single-color Micro-LED panels have been unable to meet the use requirements, and multi-color display panels have been continuously developed.

[0004] To realize multi-color display, the single-color light emitted by the pixel unit usually needs to be color-converted, i.e., color conversion. For example, a violet light or blue light pixel unit is used as an excitation light source, and a color conversion layer made of a color conversion material is used to realize color conversion, as shown in the LED display chip in FIG. 1. An epitaxial layer 10 is arranged on the upper portion of a pixel unit 30, a plurality of filling holes 101 are etched in the epitaxial layer 10, and a color conversion material is filled in the filling holes 101 to form a plurality of color conversion layers 60. Each pixel unit 30 and color conversion layer 60 correspond to each other, the single-color light emitted by the pixel unit 30 is converted into light of different colors by the corresponding color conversion layer 60 on the upper portion, and each color conversion layer 60 needs to be additionally etched with a groove on both sides to fill a light blocking material 102 to separate the adjacent color conversion layers 60 by the light blocking material 102 to eliminate light crosstalk.

[0005] The color conversion layer 60 in the color conversion scheme shown in FIG. 1 is arranged independently and separately, and needs to be prepared by separate patterning etching, which has a complex structure and a relatively complicated process. In addition, the color conversion layer has a certain requirement on the thickness, and when the thickness is too thin, light leakage occurs, resulting in poor color purity and loss of color conversion efficiency. However, when entering the field of micro display or micro projection, the pixel size is relatively small, and it is difficult to arrange the color conversion layer in the above form at this time. In addition, due to the small pixel size, the thickness of the color conversion layer is usually thinned to 5 um or even thinner, but at this time, the light leakage and efficiency of color conversion are also more serious, which finally leads to a significant decrease in color purity and final brightness, and the color conversion layer is also prone to falling off, which will cause the display quality to decrease.

[0006] Therefore, the existing Micro-LED display chip has a complex color conversion structure, a large processing difficulty, and cannot effectively guarantee the structural stability and display quality, thereby failing to meet the production and use requirements. SUMMARY

[0007] Therefore, the technical problem to be solved by the present application is to overcome the defects that the color conversion structure of the existing Micro-LED display chip is complex, the processing difficulty is large, and the structural stability and display quality cannot be effectively guaranteed.

[0008] To solve the above technical problems, the present application provides a display chip based on single-color color conversion, comprising,

[0009] a driving wafer, wherein the driving wafer comprises an anode contact;

[0010] a pixel unit arranged on the driving wafer and corresponding to the anode contact, the pixel unit comprising a P-type semiconductor layer, an active layer and an N-type semiconductor layer arranged in sequence along a first direction; the P-type semiconductor layer is electrically connected to the corresponding anode contact on the driving wafer, and the N-type semiconductor layer is electrically connected to a cathode member;

[0011] a color conversion layer, the color conversion layer covering all the pixel units and being arranged continuously, the top surface and at least part of the side surface of the pixel unit being located inside the color conversion layer.

[0012] In an embodiment of the present application, the display chip further comprises a lens, the lens corresponding to the pixel unit one by one and being located on the light output path of the corresponding pixel unit, and the lens is located on the side of the color conversion layer away from the driving wafer along the first direction.

[0013] In an embodiment of the present application, the contact surface of the color conversion layer and the lens is a first contact surface, and the focal point of the lens is located between the first contact surface and the top surface of the pixel unit.

[0014] In one embodiment of the present application, the distance between the top surface of the pixel unit and the lens vertex is r1, the contact surface of the lens and the color conversion layer is a first contact surface, the maximum distance from the center point of the first contact surface to the edge of the first contact surface is r2, and the distance between the center point of the first contact surface and the lens vertex is r3, then r1>r3≥r2.

[0015] In one embodiment of the present application, all the pixel units are arranged in an array, and a metal mesh is arranged between two adjacent pixel units, and the cathode member of each of the two adjacent pixel units is electrically connected to the metal mesh.

[0016] In one embodiment of the present application, there is a second direction perpendicular to the first direction, the minimum distance between two adjacent lenses in the second direction is D1, and the length of the metal mesh in the second direction is D2, then 0≤D1≤D2.

[0017] In one embodiment of the present application, the outer periphery of the pixel unit is covered with a first insulating layer, the first insulating layer has an opening, the first surface of the N-type semiconductor layer away from the surface of the driving wafer in the first direction is a first surface, the first surface is partially or completely exposed at the opening, and the cathode member of each pixel unit is covered outside the first insulating layer and electrically connected to the exposed part of the first surface.

[0018] In one embodiment of the present application, the first surface has a plurality of protrusions.

[0019] In one embodiment of the present application, the shapes of at least two protrusions are different.

[0020] In one embodiment of the present application, the cathode member of each pixel unit has a first connecting end and a second connecting end, the first connecting end is electrically connected to the exposed part of the first surface, the shape of the first connecting end is adapted to the shape of the first surface, and the second connecting end is used to connect the cathode member of an adjacent pixel unit.

[0021] In one embodiment of the present application, each cathode member includes a plurality of first connecting ends arranged circumferentially.

[0022] In one embodiment of the present application, at least two first connecting ends in the cathode member are connected through a transition part, and the transition part of the cathode member in the pixel unit traverses above the first surface.

[0023] In one embodiment of the present application, the outer periphery of the pixel unit is further covered with a second insulating layer, and the cathode member is located between the first insulating layer and the second insulating layer.

[0024] In one embodiment of the present application, the height of the color conversion layer along the first direction is H, and the height of the pixel unit along the first direction is h, then h < H ≤ 50h.

[0025] The present application also discloses a preparation method of a display chip based on single-color color conversion, comprising,

[0026] The driving wafer is prepared so that the driving wafer comprises an anode contact;

[0027] The compound semiconductor is connected with the driving wafer, and the compound semiconductor is processed to form a pixel unit corresponding to the anode contact; the pixel unit comprises a P-type semiconductor layer, an active layer and an N-type semiconductor layer arranged along a first direction in sequence, and the P-type semiconductor layer is electrically connected with the corresponding anode contact on the driving wafer;

[0028] The N-type semiconductor layer of each pixel unit is electrically connected with a corresponding cathode member;

[0029] The color conversion layer is prepared so that the color conversion layer covers all the pixel units and is arranged continuously, and the top surface and at least part of the side surface of the pixel unit are located inside the color conversion layer.

[0030] In one embodiment of the present application, after the preparation of the color conversion layer, a lens is formed on the color conversion layer, so that the lens and the pixel unit one-to-one correspond and are located on the light-out path of the corresponding pixel unit, and the lens is located on the side of the color conversion layer away from the driving wafer along the first direction.

[0031] In one embodiment of the present application, the compound semiconductor comprises a substrate, and an N-type semiconductor layer, an active layer and a P-type semiconductor layer formed along a direction away from the substrate in sequence;

[0032] The method for connecting the compound semiconductor with the driving wafer and processing the compound semiconductor to form a pixel unit corresponding to the anode contact comprises:

[0033] Step S1), electrically connecting the P-type semiconductor layer of the compound semiconductor with the anode contact of the driving wafer;

[0034] Step S2), removing the substrate;

[0035] Step S3), etching the compound semiconductor to obtain a pixel unit corresponding to the anode contact.

[0036] In one embodiment of the present application, before each pixel unit is electrically connected with the corresponding cathode, a first insulating layer is coated outside the pixel unit, an opening is arranged on the first insulating layer, the N-type semiconductor layer is away from the surface of the driving wafer as a first surface in the first direction, so that the first surface is partially or fully exposed at the opening, then a cathode is coated outside the first insulating layer, and the cathode of each pixel unit is electrically connected with the exposed part of the first surface.

[0037] In one embodiment of the present application, before the first insulating layer is coated outside the pixel unit, the first surface of the N-type semiconductor layer is roughened, and the roughening method comprises: treating the first surface by plasma dry etching, high-temperature acid solution etching or high-temperature alkali solution etching, so that the first surface forms a plurality of protruding parts.

[0038] In one embodiment of the present application, when the driving wafer is prepared, the adjacent anode contacts on the driving wafer are isolated by an insulating medium layer, when the compound semiconductor is prepared, a plurality of independent bonding metal pieces are arranged on the P-type semiconductor layer of the compound semiconductor, the bonding metal pieces correspond to the pixel units one by one, and when the compound semiconductor is connected with the driving wafer, the bonding metal pieces are electrically connected with the corresponding anode contacts.

[0039] The above technical solutions of the present application have the following advantages compared with the prior art:

[0040] The display chip based on single-color color conversion and the preparation method thereof have the following advantages: the color conversion layer is integrally coated on all the pixel units of the display chip and is arranged continuously, which is more convenient for processing, simplifies the processing technology, and makes the overall structure simpler; the color conversion layer can effectively avoid light leakage and efficiency problems, is more conducive to the miniaturization of the pixel size, effectively increases the fixing reliability and stability of the color conversion layer, and ensures the display quality of the chip. BRIEF DESCRIPTION OF DRAWINGS

[0041] In order to make the content of the present application more easily understood, the present application will be further described in detail below according to specific embodiments of the present application and in combination with the accompanying drawings.

[0042] FIG. 1 is a structural schematic diagram of a display chip of the prior art;

[0043] FIG. 2 is a structural schematic diagram of one scheme of a display chip based on single-color color conversion of the present application;

[0044] FIG. 3 is a structural schematic diagram of the structure of FIG. 2 after removing the color conversion layer and the lens;

[0045] Fig. 4 is a structural schematic diagram of another scheme of the display chip based on single-color color conversion of the present application;

[0046] Fig. 5 is a top view schematic diagram of the position relationship between the color conversion layer and the pixel unit of the present application;

[0047] Fig. 6 is a preparation flow chart of the display chip shown in Fig. 2;

[0048] Fig. 7 is a preparation flow chart of another scheme of the display chip of the present application;

[0049] Fig. 8 is a preparation flow chart of the display chip shown in Fig. 4;

[0050] Fig. 9 is a structural schematic diagram of the N-type semiconductor layer in the pixel unit of the present application only being partially roughened;

[0051] Fig. 10 is a schematic diagram of the arrangement of the second insulating layer on the pixel unit of the present application;

[0052] Fig. 11 is a structural schematic diagram of the display chip provided with a cathode contact of the present application;

[0053] Fig. 12 is a schematic diagram of the arrangement of the bonding metal piece of the present application;

[0054] Fig. 13 is another schematic diagram of the arrangement of the bonding metal piece of the present application;

[0055] Fig. 14 is a schematic diagram (top view) of one scheme of the cathode piece of the present application;

[0056] Fig. 15 is a schematic diagram (top view) of another scheme of the cathode piece of the present application;

[0057] Fig. 16 is a partial structural schematic diagram of the pixel unit after the roughening treatment of the present application;

[0058] Explanation of the reference signs in the attached drawings of the specification: 10, epitaxial layer; 101, filling hole; 102, light blocking material; 20, driving wafer; 201, anode contact; 202, cathode contact; 203, insulating dielectric layer; 30, pixel unit; 301, P-type semiconductor layer; 302, active layer; 303, N-type semiconductor layer; 3031, first surface; 3032, protruding part; 3033, N-type ohmic contact layer; 304, top surface; 305, side surface; 40, first insulating layer; 401, opening; 50, cathode piece; 501, first connecting end; 502, second connecting end; 503, transition part; 60, color conversion layer; 601, first contact surface; 70, lens; 80, metal mesh; 90, second insulating layer; 100, bonding metal piece; 110, compound semiconductor; 1101, substrate. DETAILED DESCRIPTION

[0059] The present application will be further described below in conjunction with the drawings and specific embodiments so that those skilled in the art can better understand and implement the present application, but the embodiments are not intended to limit the present application. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, not all. The following description of at least one exemplary embodiment is merely illustrative and is in no way limiting on the present disclosure and its applications or uses.

[0060] In the description of the present application, it should be understood that the terms "vertical", "upper", "lower", "top", "side", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second" can explicitly or implicitly include one or more features. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0061] The present embodiment provides a display chip based on monochrome color conversion and a preparation method thereof, which is more convenient for processing the color conversion structure and effectively ensures the structural stability and display quality, thereby better meeting the production and use requirements.

[0062] The structure of the present embodiment will be further described below in conjunction with FIGS. 2-16.

[0063] Embodiment one

[0064] Referring to FIGS. 2-3, the present embodiment discloses a display chip based on monochrome color conversion, comprising a driving wafer 20, a pixel unit 30 and a color conversion layer 60.

[0065] Among them, the driving wafer 20 includes an anode contact 201; the driving wafer 20 can be a CMOS driving wafer 20.

[0066] The pixel unit 30 is arranged on the driving wafer 20 and corresponds to the anode contact 201, and the pixel unit 30 includes a P-type semiconductor layer 301, an active layer 302 and an N-type semiconductor layer 303 arranged in a first direction in sequence, the active layer 302 is used for emitting light, the P-type semiconductor layer 301 is electrically connected with the corresponding anode contact 201 on the driving wafer 20, and the N-type semiconductor layer 303 is electrically connected with the cathode member 50;

[0067] As shown in FIG. 2 and FIG. 5, the color conversion layer 60 covers all the pixel units 30 of the display chip and is arranged continuously, the top surface 304 and at least part of the side surface 305 of the pixel unit 30 are located inside the color conversion layer 60, and the cathode member 50 is at least partially located inside the color conversion layer 60.

[0068] The "bottom surface" and "top surface 304" of the pixel unit 30 are relative in the first direction, the "bottom surface" of the pixel unit 30 refers to the surface of the pixel unit 30 closest to the driving wafer 20 in the first direction, and the "top surface 304" refers to the surface farthest from the driving wafer 20 in the first direction, and the "side surface 305" of the pixel unit 30 is located between the "top surface 304" and the "bottom surface" and connects the "top surface 304" and the "bottom surface". Generally, the N-type semiconductor layer 303 is farthest from the driving wafer 20 in the first direction, at this time the "top surface 304" of the pixel unit 30 is the upper surface of the N-type semiconductor layer 303, and the P-type semiconductor layer 301 is closest to the driving wafer 20 in the first direction, at this time the "bottom surface" of the pixel unit 30 is the lower surface of the P-type semiconductor layer 301.

[0069] It can be understood that the above-mentioned cathode member 50 is used for cathode connection with the driving wafer 20, since the P-type semiconductor layer 301 is electrically connected with the corresponding anode contact 201 on the driving wafer 20, when the cathode member 50 is connected with the cathode of the driving wafer 20, the N-type semiconductor layer 303 also realizes electrical connection with the cathode of the driving wafer 20, at this time a closed circuit is formed between the driving wafer 20 and the pixel unit 30, so as to drive the active layer 302 to emit light, realizing the light emitting operation of the pixel unit 30.

[0070] The color conversion layer 60 includes fluorescent powder or quantum dots, when light passes through the color conversion layer 60, the fluorescent powder or quantum dots are excited to realize color conversion. For example, the color conversion layer 60 is a mixture of quantum dots and photoresist (or silicone), the color conversion layer 60 can change the wavelength of the light emitted by the pixel unit 30, so as to change the color of the light emitted by the pixel unit 30, thereby converting the light emitted by the pixel unit 30 into light with longer wavelength. Specifically, the blue light emitted by the pixel unit 30 can be converted into green light or red light, or the purple light emitted by the pixel unit 30 can be converted into blue light, green light or red light. The color conversion layer 60 can also be a mixture of fluorescent powder and photoresist (or silicone), which will not be described here.

[0071] In the structure, the color conversion layer 60 is integrally wrapped around all the pixel units 30 and arranged continuously, that is, the color conversion layer 60 is continuously and non-interruptedly arranged in the whole pixel array area in all directions, which can effectively reduce the aspect ratio of the color conversion layer 60 and facilitate processing while ensuring the color conversion effect, and the color conversion layer 60 does not need to be etched and filled on each pixel unit 30 to form an independently separated color conversion layer 60, which simplifies the processing process and makes the overall structure simpler. Since the color conversion layer 60 can wrap the top surface 304 and at least part of the side surface 305 of the pixel unit 30, the color conversion layer 60 can be embedded in the gap between the side surfaces 305, which not only increases the thickness of the color conversion layer 60, avoids light leakage and efficiency problems of color conversion, but also facilitates miniaturization of the pixel size, effectively increases the fixing reliability and stability of the color conversion layer 60, and ensures the display quality of the chip.

[0072] In some embodiments, the display chip further comprises a lens 70, the lens 70 and the pixel unit 30 one-to-one correspond and are located on the light emitting path of the corresponding pixel unit 30, and the lens 70 is located on the side of the color conversion layer 60 away from the driving wafer 20 along the first direction.

[0073] Through the arrangement of the lens 70, a collimation structure can be introduced to better prevent the light crosstalk problem between the pixel units 30, that is, the light after color conversion is collimated through the lens 70 to complete the crosstalk optimization between pixels.

[0074] The surface of the lens 70 can be a smooth curved surface or an uneven curved surface formed by multiple steps.

[0075] In some embodiments, the contact surface of the color conversion layer 60 and the lens 70 is defined as a first contact surface 601, as shown in FIG. 2, the focal point of the lens 70 is located between the first contact surface 601 and the top surface 304 of the pixel unit, which can maximize the collimation of the light that may cause crosstalk, thereby improving the anti-crosstalk and light collimation effect.

[0076] In some embodiments, the distance between the top surface 304 of the pixel unit 30 and the vertex of the lens 70 is r1, the contact surface of the lens 70 and the color conversion layer 60 is a first contact surface 601, the maximum distance from the center point of the first contact surface 601 to the edge of the first contact surface 601 is r2, the distance between the center point of the first contact surface 601 and the vertex of the lens 70 is r3, and r1>r3≥r2. This scheme makes the shape of the lens 70 closer to a half olive ball, which is more conducive to compressing the light emitting angle compared to other shapes, thereby improving the collimation effect of the emitted light and further improving the anti-crosstalk effect between the pixel units 30.

[0077] Further, 1um≤r2≤40um, to better ensure the anti-crosstalk effect between the pixel units.

[0078] In some embodiments, the cathode member 50 can be a transparent conductive film, and the cathode connection can be directly realized through the cathode member 50. The transparent conductive film includes a single layer or a stack of transparent conductive metal oxides such as ITO, ZnO, IZO, or a metal composite structure thereof with Al, Ag, Au, etc.

[0079] In some other embodiments, all the pixel units 30 are arranged in an array, and a metal mesh 80 is arranged between two adjacent pixel units 30, and the cathode members 50 of the two adjacent pixel units 30 are both electrically connected to the metal mesh 80 therebetween, so as to realize the cathode current enhancement through the metal mesh 80 and ensure the cathode connection effect.

[0080] Specifically, as shown in FIG. 5, the pixel array can include at least 100 pixel units 30, and the specific number can be set according to actual needs, which is not limited here.

[0081] The above-mentioned mode realizes the cathode connection through the "cathode member 50 + metal mesh 80", and can realize the cathode current enhancement or directly through the metal mesh 80. The metal mesh 80 can be a single layer or multiple layers of Al, Ni, Ti, Cr, Pt, Au, etc. Specifically, the metal mesh 80 can be 300 nm Al + 100 nm Ti + 50 nm Pt + 1000 nm Au.

[0082] Further, the height of the pixel unit 30 along the first direction is h, and the height of the metal mesh 80 along the first direction is L, and L≥0.1h, so as to better ensure the cathode current enhancement effect.

[0083] It can be understood that the height h of the pixel unit 30 refers to the distance between the bottom surface and the top surface 304 of the pixel unit 30 in the first direction, which is usually the distance between the lower surface of the P-type semiconductor layer 301 and the upper surface of the N-type semiconductor layer 303.

[0084] Specifically, the height L of the metal mesh 80 along the first direction is 200 nm to 5000 nm, so as to better ensure the cathode current enhancement effect.

[0085] In some embodiments, the length D2 of the metal mesh 80 along the second direction can be 0.2 um to 10 um, which can well balance the horizontal space occupation and the current expansion, and also facilitates the miniaturization of the chip while ensuring the current expansion.

[0086] In some embodiments, the angle k between the metal mesh 80 and the driving unit is 90°±45°. Preferably, k≥90°, which is more easily realized in the process.

[0087] Further, the minimum distance between two adjacent lenses 70 in the second direction is D1, and the length of the metal mesh 80 in the second direction is D2, and 0≤D1≤D2, wherein the second direction is perpendicular to the first direction. That is, the minimum distance between two adjacent lenses 70 in the second direction is less than or equal to the length of the metal mesh therebetween. By the above arrangement, the light crosstalk phenomenon between pixels can be maximally reduced. If D1>D2, the anti-crosstalk effect will be reduced.

[0088] The first direction is generally the direction away from the driving unit, and the second direction is the direction perpendicular to the first direction. In this document, "up, down" or "top, bottom" are relative in the first direction.

[0089] In the embodiment, the outer periphery of the pixel unit 30 is covered by the first insulating layer 40, the first insulating layer 40 has an opening 401, the N-type semiconductor layer 303 has a first surface 3031 away from the surface of the driving wafer 20 in the first direction, and the first surface 3031 is partially exposed at the opening 401. The cathode member 50 of each pixel unit 30 is covered outside the first insulating layer 40 and electrically connected to the exposed part of the first surface 3031.

[0090] The P-type semiconductor layer 301 and the N-type semiconductor layer 303 inside the pixel unit 30 can be insulated by the first insulating layer 40, so as to avoid short circuit and leakage between them.

[0091] In some embodiments, the first surface 3031 has a plurality of protrusions 3032, which can be regularly distributed or randomly distributed, so as to reduce the total reflection phenomenon of the light emitting area and improve the light extraction efficiency of the light emitting area.

[0092] Preferably, the length of the protrusion 3032 in the first direction and the second direction is 50-800 nm, and the second direction is perpendicular to the first direction. The size reaches the nanometer level, which is more suitable for Micro-LED.

[0093] Further, the length of the protrusion 3032 in the first direction and the second direction is 80-250 nm.

[0094] In some embodiments, as shown in FIG. 16, the shapes of at least two protrusions 3032 are different, which is more conducive to reducing the processing difficulty and improving the processing efficiency.

[0095] For example, as shown in FIG. 16, the protrusion 3032 can be spherical, pyramidal or conical, and the pyramidal shape can be hexagonal pyramid, dodecahedral pyramid, etc.

[0096] Specifically, the alkali solution with PH value of 8-10 can be prepared by mixing ammonium hydroxide and organic amine, and the roughening of the first surface 3031 can be performed by soaking in the solution at 80°C for 30 minutes, so as to obtain the mixed protruding parts 3032 structure of spherical, hexagonal pyramid, dodecahedron and the like as shown in FIG. 16.

[0097] In some embodiments, as shown in FIG. 14 and FIG. 15, the cathode member 50 of each pixel unit 30 has a first connecting end 501 and a second connecting end 502, the first connecting end 501 is electrically connected with the exposed part of the corresponding first surface 3031, the shape of the first connecting end 501 is adapted to the shape of the first surface 3031, and the second connecting end 502 is used to connect with the cathode member 50 of the adjacent pixel unit 30.

[0098] For example, the first surface 3031 is uneven and has a plurality of protruding parts 3032, and the first connecting end 501 has a plurality of recessed parts corresponding to the protruding parts 3032, so as to realize the clamping.

[0099] Further, each cathode member 50 includes a plurality of first connecting ends 501 arranged circumferentially, which can be located at the edges of the first surface 3031, such as the exposed parts at two corners or four corners of the first surface 3031, so as to better ensure the stability of the electrical contact.

[0100] In some embodiments, at least two first connecting ends 501 in the cathode member 50 are connected by a transition part 503, and the transition part 503 of the cathode member 50 in the pixel unit 30 traverses above the first surface 3031, so as to better ensure the stability of the cathode connection and facilitate the enhancement of the cathode current conduction.

[0101] In some embodiments, as shown in FIG. 2, the height of the color conversion layer 60 along the first direction is H, and the height of the pixel unit 30 along the first direction is h, then h < H ≤ 50h, which can better prevent the light crosstalk between pixels and reduce the light leakage caused by insufficient thickness of the color conversion layer.

[0102] It can be understood that the height H of the color conversion layer 60 refers to the distance between the bottom surface of the lowest part and the top surface of the highest part of the color conversion layer 60 in the first direction, and the height h of the pixel unit 30 refers to the distance between the bottom surface and the top surface 304 of the pixel unit 30 in the first direction, which is usually the distance between the lower surface of the P-type semiconductor layer 301 and the upper surface of the N-type semiconductor layer 303.

[0103] Preferably, 30h ≤ H ≤ 40h, and the optimization crosstalk effect in this range is optimal.

[0104] Further, the color conversion layer 60 has a length H in the first direction of 2 um to 100 um, for example, the color conversion layer 60 is formed by a mixture of 30 um thick fluorescent powder and silica gel to completely cover the pixel array, and the color conversion layer 60 is continuous in the entire row of pixels.

[0105] In some embodiments, the P-type semiconductor layer 301 in the pixel unit 30 is electrically connected to the corresponding anode contact 201 by the independent bonding metal piece 100, and the anode contacts 201 on the driving wafer 20 are isolated by the insulating medium layer 203. The anode contact 201 is a conductive metal.

[0106] As shown in FIGS. 12 and 13, the independent bonding metal piece 100 can be prepared when the compound semiconductor 110 is prepared to obtain a patterned bonding metal piece 100, the bonding metal piece 100 between the compound semiconductor 110 can be filled with the insulating medium layer 203, and similarly, each anode contact 201 can be prepared when the driving wafer 20 is prepared. Then the compound semiconductor 110 and the driving wafer 20 are bonded, and the size of the bonding metal piece 100 or the anode contact 201 prepared before bonding can be larger, and the size of the bonding metal piece 100 or the anode contact 201 can be further reduced after subsequent bonding. In this way, a large bonding metal piece 100 is obtained by patterning the bonding layer before bonding, which is more conducive to stress control during the bonding process and avoids excessive warping. Compared with the design of a full-surface bonding layer, the amount of metal on the wafer after patterning is less, especially the noble metal can be recycled, which is more cost-effective. At the same time, the non-full-surface metal can be used to arrange the alignment marks required for the bonding, exposure and other processes on the driving wafer 20 in advance, which is not blocked by the metal and the process is easier to implement. In addition, the large block of patterned alignment bonding has a significantly reduced accuracy requirement and is easier to implement.

[0107] Further, the length of the bonding metal piece 100 in the second direction can be greater than the length of a single anode contact 201 in the second direction, so that the bonding metal piece 100 has a larger size, which is conducive to reducing the alignment bonding accuracy of the bonding metal piece 100 and the anode contact 201, and is easier to implement.

[0108] In some embodiments, a P-type ohmic contact layer made of a conductive material, which can be a transparent conductive film, can also be provided on the P-type semiconductor layer 301 of each pixel unit 30, and the P-type semiconductor layer 301 is electrically connected to the corresponding anode contact 201 through the P-type ohmic contact layer. The P-type ohmic contact layer can be located between the P-type semiconductor layer 301 and the bonding metal piece 100.

[0109] In some embodiments, a reflective metal layer can also be provided on the P-type ohmic contact layer. The reflective metal layer is located between the P-type ohmic contact layer and the bonding metal piece 100.

[0110] In some embodiments, the N-type semiconductor layer of each pixel unit 30 is electrically connected through the N-type ohmic contact layer 3033 and the cathode member 50.

[0111] In some embodiments, as shown in FIG. 11, the driving wafer 20 is further provided with a cathode contact 202, the cathode contact 202 and the anode contact 201 are both conductive metals, the adjacent anode contact 201 and the cathode contact 202 are isolated by an insulating medium layer 203, and the cathode member 50 of each pixel unit 30 is electrically connected with the corresponding cathode contact 202.

[0112] In an embodiment, the shape of the pixel unit 30 includes but is not limited to a circle, a trapezoid, a hexagon, or an octagon.

[0113] In some embodiments, the angle θ between the pixel unit 30 and the driving wafer 20 is 45°-90°, and the length F of the pixel unit 30 in the second direction is 1-100 um.

[0114] The display chip in the above embodiments can be a Micro-LED chip, a Micro-Laser chip, or other optoelectronic devices.

[0115] The shape of the pixel unit can be a circle, a trapezoid, a hexagon, or an octagon, etc.

[0116] As shown in FIG. 6, the present embodiment further discloses a preparation method of a display chip based on single-color color conversion, comprising the following steps:

[0117] 1) preparing the driving wafer 20 so that the driving wafer 20 comprises the anode contact 201; at the same time, the preparation of the compound semiconductor 110 can also be completed;

[0118] The above driving wafer 20 can be a CMOS driving wafer 20.

[0119] 2) as shown in stages a-c in FIG. 6, connecting the compound semiconductor 110 and the driving wafer 20, and processing the compound semiconductor 110 to form the pixel unit 30 corresponding to the anode contact 201; the pixel unit 30 comprises a P-type semiconductor layer 301, an active layer 302, and an N-type semiconductor layer 303 arranged in sequence along a first direction, and the P-type semiconductor layer 301 is electrically connected with the corresponding anode contact 201 on the driving wafer 20;

[0120] 3) as shown in stage e in FIG. 6, electrically connecting the N-type semiconductor layer 303 of each pixel unit 30 with the corresponding cathode member 50;

[0121] 4) As shown in FIG. 6, stage f, the color conversion layer 60 is prepared so that the color conversion layer 60 covers all the pixel units 30 and is arranged continuously, the top surface 304 and at least part of the side surface 305 of the pixel unit 30 are located inside the color conversion layer 60, and the cathode member 50 is also at least partially located inside the color conversion layer 60.

[0122] In some embodiments, as shown in FIG. 6, stage g, after the preparation of the color conversion layer 60 is completed, a lens 70 is further formed on the color conversion layer 60, so that the lens 70 corresponds to the pixel unit 30 one by one and is located on the light emitting path of the corresponding pixel unit 30, and the lens 70 is located on the side of the color conversion layer 60 away from the driving wafer 20 in the first direction, so as to realize light collimation through the lens 70 and reduce light crosstalk.

[0123] In some embodiments, the compound semiconductor 110 generally refers to a compound formed by two or more elements. For example, the compound semiconductor herein mainly refers to an epitaxial material for light emitting diode, such as an InGaN ternary material system or an AlGaInP quaternary material system.

[0124] In some embodiments, the compound semiconductor 110 includes a substrate 1101, and an N-type semiconductor layer 303, an active layer 302 and a P-type semiconductor layer 301 formed in sequence away from the substrate 1101; the active layer 302 is used for emitting light.

[0125] Taking the field of Micro-LED as an example, some compound materials involved in the present embodiment are shown in Table 1. In some practical applications, the film layer of the compound semiconductor is more complex, or there is cross use of materials, mainly including P-type semiconductor layer material, N-type semiconductor layer material and active layer (MQW active quantum well) sandwiched therebetween.

[0126] Table 1: Compound film layer material table

[0127] In some embodiments, the compound semiconductor 110 is connected with the driving wafer 20, and a method for processing the compound semiconductor 110 to form the pixel unit 30 corresponding to the anode contact 201 includes the following steps.

[0128] Step S1), as shown in FIG. 6, stage a, the P-type semiconductor layer 301 of the compound semiconductor 110 is electrically connected with the anode contact 201 of the driving wafer 20.

[0129] Step S2), as shown in FIG. 6, stage b, the substrate 1101 is removed.

[0130] Step S3), as shown in FIG. 6, stage c, the compound semiconductor 110 is etched to obtain the pixel unit 30 corresponding to the anode contact 201.

[0131] Further, the compound semiconductor 110 and the driving wafer 20 are connected by thermal compression bonding. Specifically, in step S1), the surfaces of the compound semiconductor 110 and the driving wafer 20 are activated by argon or nitrogen plasma, and then the thermal compression bonding is performed on the rough wafer profile. The bonding temperature is 310°C, and the pressure is 5000 Kg. By the bonding, the bonding metal piece 100 and the anode contact 201 and the layer where the anode contact 201 is located are integrated together.

[0132] Further, as shown in stage d of FIG. 6, before the N-type semiconductor layer 303 of each pixel unit 30 is electrically connected to the corresponding cathode piece 50, the first insulating layer 40 is coated outside the pixel unit 30. The opening 401 is arranged on the first insulating layer 40. The N-type semiconductor layer 303 has a first surface 3031 away from the surface of the driving wafer 20 in the first direction, so that the first surface 3031 is partially exposed at the opening 401. Then, the cathode piece 50 is coated outside the first insulating layer 40, and the cathode piece 50 of each pixel unit 30 is electrically connected to the exposed part of the first surface 3031, so as to realize the electrical connection between the cathode piece and the N-type semiconductor layer 303.

[0133] The first insulating layer 40 is made of one or more of aluminum oxide, silicon oxide, and silicon nitride.

[0134] When the first insulating layer 40 is prepared, the whole surface can be coated, and then the top surface 304 of the pixel unit 30 is patterned to form the opening. The opening can partially open the top surface 304 of the pixel unit 30, and can be realized by single opening or multiple openings.

[0135] In some embodiments, before the first insulating layer 40 is coated outside the pixel unit 30, the first surface 3031 of the N-type semiconductor layer 303 needs to be roughened. The roughening method includes: treating the first surface 3031 by plasma dry etching, high-temperature acid solution etching, or high-temperature alkali solution etching, so as to form a plurality of protrusions 3032 on the first surface 3031. Compared with the traditional micron-level roughening or coarsening, the protrusions 3032 formed by the method have a size of 50 nm to 800 nm.

[0136] For example, the size of the protrusions 3032 obtained by treating the first surface with a mixed alkali solution of high-temperature sodium hydroxide (NaOH) and hydrogen peroxide (H2O2) is 80 nm to 250 nm.

[0137] Preferably, as shown in FIG. 9, the roughening can be local roughening, which is used to control better ohmic contact and avoid voltage abnormality caused by the roughening structure.

[0138] In one embodiment, as shown in FIG. 4, the roughening process can be omitted before the first insulating layer 40 is coated on the outside of the pixel unit 30. A transparent conductive film layer can be provided on the first surface 3031 of the N-type semiconductor layer 303 as an N-type ohmic contact layer 3033 to achieve electrical connection through the N-type ohmic contact layer 3033 and the cathode member 50. The detailed preparation process is shown in FIG. 8.

[0139] In one embodiment, the drive wafer 20 is prepared such that the adjacent anode contacts 201 on the drive wafer 20 are isolated by the insulating medium layer 203. The compound semiconductor 110 is prepared such that a plurality of independent bonding metal members 100 are provided on the P-type semiconductor layer 301 of the compound semiconductor 110. The bonding metal members 100 correspond to the pixel units 30 one by one, and the number of the bonding metal members 100 is consistent with the number of the final pixel units 30. Then, when the compound semiconductor 110 and the drive wafer 20 are thermally pressed and bonded, the bonding metal members 100 are electrically connected to the corresponding anode contacts 201.

[0140] Further, the bonding metal member 100 can be a single-layer structure made of one of aluminum (Al), gold (Au), and copper (Cu), a laminated structure of nickel (Ni), gold (Au), copper (Cu), etc. and tin (Sn), or a laminated structure of gold (Au) and indium (In), germanium (Ge), or silicon (Si). The bonding metal member 100 can be obtained by plating and etching, or by plating after pattern masking. The plating after pattern masking is preferred, which is beneficial for recycling of the noble metal and reduces the cost.

[0141] The above-mentioned method can obtain independent bonding metal members 100 by patterning the bonding layer before bonding, which is more beneficial for stress control in the subsequent bonding process, avoids deformation, and is more suitable for reducing the alignment precision and easier to implement.

[0142] Specifically, in one embodiment, the bonding metal member 100 includes a 1 nm adhesion layer of metal Cr, a 50 nm reflective layer of metal Al, a 50 nm adhesion layer of metal Ti, a 40 nm bonding layer of metal Ni, a 100 nm bonding layer of metal Sn, and a 10 nm bonding layer of metal Au.

[0143] In some embodiments, while the plurality of bonding metal members 100 are prepared on the compound semiconductor 110, the adjacent bonding metal members 100 are filled with the insulating medium layer 203 to achieve insulation and isolation. The medium layer can be inorganic substances such as silicon oxide, silicon nitride, carbon-doped silicon nitride, or nitrogen-doped amorphous carbon, or organic substances such as polyimide, etc. Similarly, the adjacent anode contacts 201 on the drive wafer 20 can also be filled with the insulating medium layer 203.

[0144] In some embodiments, as shown in Fig. 6, e stage, when the N-type semiconductor layer 303 of each pixel unit 30 is electrically connected with the corresponding cathode member 50, a metal mesh 80 is arranged between the two adjacent pixel units 30, the cathode member 50 of the two adjacent pixel units 30 is electrically connected with the metal mesh 80, and the color conversion layer 60 covers at least part of the metal mesh 80, so as to realize the cathode current enhancement through the metal mesh 80.

[0145] Embodiment Two

[0146] The main difference between this embodiment and Embodiment One is that, as shown in Fig. 7, a stage, the pixel unit 30 is covered with a first insulating layer 40, the first insulating layer 40 has an opening 401, the N-type semiconductor layer 303 has a first surface 3031 away from the surface of the driving wafer 20 in the first direction, the first surface 3031 is fully exposed at the opening 401, and the cathode member 50 of each pixel unit 30 is covered outside the first insulating layer 40 and is electrically connected with the exposed part of the first surface 3031.

[0147] When the first insulating layer 40 is prepared, a full-surface coating method can be used, and then the pixel unit 30 top surface 304 is patterned to open the hole. The hole can fully open the pixel unit 30 top surface 304.

[0148] The preparation method of the display chip of this embodiment is shown in Fig. 7, and the basic steps are basically the same, except that the size and method of the opening 401 of the first insulating layer 40 are different, which will not be described here.

[0149] In this embodiment, the cathode connection can only use the cathode member 50, which can be a transparent conductive film, or use the cathode connection method of “cathode member 50 + metal mesh 80” as shown in Fig. 7, d stage, and the metal mesh 80 is arranged between the adjacent pixel units 30, so that the metal mesh 80 and the adjacent cathode member 50 are electrically connected.

[0150] Embodiment Three

[0151] The main difference between this embodiment and Embodiment One is that, as shown in Fig. 10, the pixel unit 30 is further covered with a second insulating layer 90, and the cathode member 50 is located between the first insulating layer 40 and the second insulating layer 90.

[0152] Among them, the second insulating layer 90 is used to block the contact between the organic material in the subsequent color conversion layer 60 and the structure of the pixel unit 30, so as to avoid damage to the cathode connection structure. For example, when the color conversion layer 60 contains a trace of acid, it will corrode some metal mesh 80 materials.

[0153] The second insulation layer 90 is made of one or more of aluminum oxide, silicon oxide, silicon nitride, etc.

[0154] The second insulation layer 90 is prepared after the preparation of the cathode member 50 is completed, so that the second insulation layer 90 covers the cathode member 50.

[0155] Embodiment Four

[0156] The main difference between this embodiment and Embodiment One is that this embodiment is provided with the lens 70, which is directly made from a part of the color conversion layer 60, that is, the color conversion layer 60 is integrally wrapped around all the pixel units of the display chip and arranged continuously, and a part of the upper part of the color conversion layer 60 is directly made into an arched shape part by etching or other means to be used as a lens.

[0157] Further, the lens 70 and the pixel unit 30 are one-to-one corresponding and located on the light-emitting path of the corresponding pixel unit 30; the lens 70 can be located on the side of the color conversion layer 60 away from the driving wafer 20 along the first direction.

[0158] The surface of the lens 70 can be a smooth curved surface or an uneven curved surface formed by multiple steps.

[0159] In the display chip prepared in each embodiment, the color conversion layer is integrally wrapped around all the pixel units of the display chip and arranged continuously, which is more convenient for processing and simplifies the processing technology, not only makes the overall structure simpler, but also avoids color conversion light leakage and efficiency problems, and is more conducive to the miniaturization of the pixel size, effectively increases the fixing reliability and stability of the color conversion layer, and ensures the display quality of the chip, realizes higher brightness and is more suitable for Micro-LED use.

[0160] All the optional technical solutions can be combined to form optional embodiments of the present application, that is, any number of embodiments can be combined to meet the needs of different application scenarios, which are all within the protection scope of the present application and will not be described one by one here.

[0161] It should be noted that the above embodiments are only examples for clear illustration, and are not a limitation on the embodiments. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, it is not necessary or possible to exhaust all the embodiments. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A display chip based on monochrome color conversion, characterized in that: include, A driving wafer, wherein the driving wafer includes an anode contact; A pixel unit is disposed on the driving wafer and corresponds to the anode contact. The pixel unit includes a P-type semiconductor layer, an active layer, and an N-type semiconductor layer disposed sequentially along a first direction. The P-type semiconductor layer is electrically connected to the corresponding anode contact on the driving wafer, and the N-type semiconductor layer is electrically connected to the cathode. A color transfer layer that covers all the pixel units and is arranged continuously, wherein the top surface and at least part of the side surfaces of the pixel units are located inside the color transfer layer.

2. The display chip based on monochrome color conversion according to claim 1, characterized in that: It also includes lenses, which correspond one-to-one with the pixel units and are located on the light-emitting path of the corresponding pixel units. The lenses are all located on the side of the color transfer layer away from the driving wafer along the first direction.

3. The display chip based on monochrome color conversion according to claim 2, characterized in that: The contact surface between the color transfer layer and the lens is the first contact surface, and the focal point of the lens is located between the first contact surface and the top surface of the pixel unit.

4. The display chip based on monochrome color conversion according to claim 2, characterized in that: The distance between the top surface of the pixel unit and the vertex of the lens is r1. The contact surface between the lens and the color transfer layer is the first contact surface. The maximum distance from the center point of the first contact surface to the edge of the first contact surface is r2. The distance between the center point of the first contact surface and the vertex of the lens is r3. Then r1>r3≥r2.

5. The display chip based on monochrome color conversion according to claim 2, characterized in that: All the pixel units are arranged in an array, with a metal mesh grid between two adjacent pixel units, and the cathodes of two adjacent pixel units are electrically connected to the metal mesh grid.

6. The display chip based on monochrome color conversion according to claim 5, characterized in that: Having a second direction perpendicular to the first direction, with a minimum distance of D1 between two adjacent lenses in the second direction, and a length of D2 along the second direction of the metal mesh, then 0 ≤ D1 ≤ D2.

7. The display chip based on monochrome color conversion according to claim 1, characterized in that: The outer periphery of the pixel unit is covered by a first insulating layer with an opening. The surface of the N-type semiconductor layer away from the driving wafer along a first direction is a first surface. The first surface is partially or fully exposed at the opening. The cathode of each pixel unit is covered outside the first insulating layer and electrically connected to the exposed portion of the first surface.

8. The display chip based on monochrome color conversion according to claim 7, characterized in that: The first surface has multiple protrusions.

9. The display chip based on monochrome color conversion according to claim 8, characterized in that: At least two of the protrusions have different shapes.

10. The display chip based on monochrome color conversion according to claim 7, characterized in that: Each pixel unit's cathode has a first connection end and a second connection end. The first connection end is electrically connected to an exposed portion of the first surface. The shape of the first connection end is adapted to the shape of the first surface. The second connection end is used to connect to the cathode of an adjacent pixel unit.

11. The display chip based on monochrome color conversion according to claim 10, characterized in that: Each of the cathode elements includes a plurality of first connection ends arranged circumferentially.

12. The display chip based on monochrome color conversion according to claim 11, characterized in that: At least two first connection ends of the cathode are connected by a transition portion, and the transition portion of the cathode in the pixel unit extends across the first surface.

13. The display chip based on monochrome color conversion according to claim 7, characterized in that: The outer periphery of the pixel unit is also covered with a second insulating layer, and the cathode is located between the first insulating layer and the second insulating layer.

14. The display chip based on monochrome color conversion according to claim 1, characterized in that: If the height of the color transfer layer along the first direction is H, and the height of the pixel unit along the first direction is h, then h < H ≤ 50h.

15. A method for fabricating a display chip based on monochrome color conversion, characterized in that: include, A driving wafer is fabricated such that the driving wafer includes an anode contact; The compound semiconductor is connected to the driving wafer, and the compound semiconductor is processed to form a pixel unit corresponding to the anode contact; The pixel unit includes a P-type semiconductor layer, an active layer, and an N-type semiconductor layer arranged sequentially along a first direction. The P-type semiconductor layer is electrically connected to the corresponding anode contact on the driving wafer. Each pixel unit's N-type semiconductor layer is electrically connected to its corresponding cathode. A color transfer layer is prepared such that it covers all the pixel units and is arranged continuously, with the top surface and at least part of the side surfaces of the pixel units located inside the color transfer layer.

16. The preparation method according to claim 15, characterized in that: After the color transfer layer is fabricated, lenses need to be formed on the color transfer layer so that the lenses correspond one-to-one with the pixel units and are located on the light emission path of the corresponding pixel units. The lenses are all located on the side of the color transfer layer away from the driving wafer along the first direction.

17. The preparation method according to claim 15, characterized in that: The compound semiconductor includes a substrate, and an N-type semiconductor layer, an active layer, and a P-type semiconductor layer formed sequentially in a direction away from the substrate; A method for connecting a compound semiconductor to the driving wafer and processing the compound semiconductor to form a pixel unit corresponding to the anode contact includes: Step S1) Electrically connect the P-type semiconductor layer of the compound semiconductor to the anode contact of the driving wafer; Step S2): Remove the substrate; Step S3) Etching the compound semiconductor to obtain a pixel unit corresponding to the anode contact.

18. The preparation method according to claim 15, characterized in that: Before electrically connecting the N-type semiconductor layer of each pixel unit to the corresponding cathode, a first insulating layer is wrapped around the outside of the pixel unit. An opening is provided on the first insulating layer. The surface of the N-type semiconductor layer away from the driving wafer along a first direction is the first surface, so that the first surface is partially or completely exposed at the opening. Then, a cathode is wrapped around the outside of the first insulating layer, and the cathode of each pixel unit is electrically connected to the exposed part of the first surface.

19. The preparation method according to claim 18, characterized in that: Before the first insulating layer is coated on the outside of the pixel unit, the first surface of the N-type semiconductor layer needs to be roughened. The roughening method includes: treating the first surface by plasma dry etching, high-temperature acid solution etching or high-temperature alkaline solution etching, so that the first surface forms multiple protrusions.

20. The preparation method according to claim 15, characterized in that: When fabricating the driver wafer, adjacent anode contacts on the driver wafer are isolated by an insulating dielectric layer. When fabricating the compound semiconductor, multiple independent bonding metal parts are also set on the P-type semiconductor layer of the compound semiconductor. Each bonding metal part corresponds to a pixel unit. When the compound semiconductor and the driver wafer are connected, the bonding metal parts and the corresponding anode contacts are electrically connected.

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