Display chip based on single-color color conversion

Abstract

The utility model relates to a display chip based on monochromatic color conversion, which comprises a driving wafer, a pixel unit and a color conversion layer, and is characterized in that the driving wafer comprises an anode contact; the pixel unit is arranged on the driving wafer and corresponds to the anode contact, and the pixel unit comprises a P-type semiconductor layer, an active layer and an N-type semiconductor layer which are sequentially arranged in the first direction; the P-type semiconductor layer is electrically connected with a corresponding anode contact on the driving wafer, and the N-type semiconductor layer is electrically connected with the cathode piece; the color conversion layer covers all the pixel units and is continuously arranged, and the top surfaces and at least part of the side surfaces of the pixel units are located in the color conversion layer. According to the utility model, the processing is more convenient, the overall structure is simpler, not only can the problems of light leakage and efficiency of color conversion be effectively avoided, but also the fixing reliability and stability of the color conversion layer are effectively improved, so that the display quality of the chip is ensured.

Description

Technical Field

[0001] The utility model relates to the technical field of semiconductors, in particular to a display chip based on monochrome color conversion. Background Art

[0002] Micro-LED (Micro Light Emitting Diode) is also known as micro light-emitting diode. Micro-LED display chips have a high-density pixel array, and each pixel unit in the pixel array can emit light by itself. Each pixel unit of a Micro-LED display chip can usually only emit light of one color, so Micro-LED display panels are usually monochrome panels, 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. As people's requirements for imaging continue to increase, monochrome Micro-LED panels can no longer meet usage needs, and colorful display panels continue to develop.

[0003] In order to realize colorful display, it is generally necessary to convert the monochromatic light emitted by the pixel unit into color, such as using purple or blue light pixel unit as the excitation light source, and realizing color conversion through a color conversion layer made of color conversion material, such as Figure 1 In the LED display chip shown, an epitaxial layer 10 is arranged on the upper part of the 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 corresponds to a color conversion layer 60 one by one, and the monochromatic light emitted by the pixel unit 30 is converted into light of different colors through the corresponding color conversion layer 60 on the upper part and emitted, and grooves need to be additionally etched on both sides of each color conversion layer 60 to fill with light blocking material 102, so as to separate adjacent color conversion layers 60 by the light blocking material 102 to eliminate optical crosstalk.

[0004] Figure 1 In the color conversion scheme shown in this manner, each color conversion layer 60 is independently separated and needs to be separately prepared by graphic etching. The structure is complex and the related processes are relatively cumbersome. In addition, the above-mentioned color conversion layer has certain requirements on thickness. When the thickness is too thin, light leakage problems will occur, 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. At this time, it is difficult to arrange the above-mentioned graphic color conversion layer. Due to the small pixel size, the thickness of the color conversion layer is usually reduced to 5um or even thinner. However, at this time, the light leakage and efficiency problems of color conversion are also relatively serious, which ultimately leads to a significant decrease in color purity and final brightness, and the color conversion layer is also prone to falling off, all of which will cause a decrease in display quality.

[0005] Therefore, the color conversion structure in existing Micro-LED display chips is complex and difficult to process, and cannot effectively guarantee structural stability and display quality, thus failing to meet production and usage requirements. Utility Model Content

[0006] To this end, the technical problem to be solved by the present invention is to overcome the defects of the existing Micro-LED display chip, such as the complex color conversion structure and the great difficulty in processing, which makes it impossible to effectively guarantee the structural stability and display quality.

[0007] In order to solve the above technical problems, the utility model provides a display chip based on monochrome color conversion, comprising:

[0008] A driving wafer, wherein the driving wafer includes an anode contact;

[0009] A pixel unit, the pixel unit is arranged on the driving wafer and corresponds to the anode contact, the pixel unit comprises 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 the cathode member;

[0010] A color conversion layer covers all of the pixel units and is arranged continuously, and a top surface and at least a portion of a side surface of the pixel unit are located inside the color conversion layer.

[0011] In one embodiment of the present invention, the display chip further comprises a lens, which corresponds one-to-one to the pixel unit and is located on the light output path of the corresponding pixel unit, and the lens is located on a side of the color conversion layer away from the driving wafer along the first direction.

[0012] In one embodiment of the present invention, the contact surface between the color conversion layer and the lens is a first contact surface, and the focus of the lens is located between the first contact surface and the top surface of the pixel unit.

[0013] In one embodiment of the present invention, 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 conversion 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, and the distance between the center point of the first contact surface and the vertex of the lens is r3, then r1>r3≥r2.

[0014] In one embodiment of the present invention, all the pixel units are arranged in an array, a metal grid is provided between two adjacent pixel units, and the cathode members of the two adjacent pixel units are electrically connected to the metal grid.

[0015] In one embodiment of the present invention, 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 grid along the second direction is D2, then 0≤D1≤D2.

[0016] In one embodiment of the utility model, the periphery of the pixel unit is covered with a first insulating layer, the first insulating layer has an opening, the surface of the N-type semiconductor layer away from the driving wafer along the first direction is the first surface, the first surface is partially or fully exposed at the opening, and the cathode component of each pixel unit is covered on the outside of the first insulating layer and electrically connected to the exposed portion of the first surface.

[0017] In one embodiment of the present invention, the first surface has a plurality of protrusions.

[0018] In one embodiment of the present invention, at least two protrusions have different shapes.

[0019] In one embodiment of the utility model, the cathode component of each pixel unit has a first connection end and a second connection end, the first connection end is electrically connected to the exposed portion of the first surface, the shape of the first connection end is adapted to the shape of the first surface, and the second connection end is used to connect to the cathode component of an adjacent pixel unit.

[0020] In one embodiment of the present invention, each of the cathode components includes a plurality of first connection ends arranged in a circumferential direction.

[0021] In one embodiment of the present invention, at least two first connection ends of the cathode member are connected via a transition portion, and the transition portion of the cathode member in the pixel unit crosses above the first surface.

[0022] In one embodiment of the present invention, the 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.

[0023] In one embodiment of the present invention, the height of the color conversion layer along the first direction is H, the height of the pixel unit along the first direction is h, and then h<H≤50h.

[0024] The above technical solution of the utility model has the following advantages compared with the prior art:

[0025] The display chip based on monochrome color conversion described in the utility model has a color conversion layer that integrally covers all pixel units of the display chip and is arranged continuously, which is easier to process, simplifies the processing technology, and makes the overall structure simpler. It can not only effectively avoid light leakage and efficiency problems caused by color conversion, but also is more conducive to the miniaturization of pixel size. At the same time, it also effectively increases the fixing reliability and stability of the color conversion layer, so that the display quality of the chip can be guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to make the content of the utility model more clearly understood, the utility model is further described in detail below based on specific embodiments of the utility model in combination with the accompanying drawings.

[0027] Figure 1 It is a schematic diagram of the structure of a display chip in the prior art;

[0028] Figure 2 This is a schematic structural diagram of a solution of a display chip based on monochrome color conversion of the utility model;

[0029] Figure 3 yes Figure 2 Schematic diagram of the structure after removing the color conversion layer and lens in the middle structure;

[0030] Figure 4 It is a structural schematic diagram of another solution of the display chip based on monochrome color conversion of the utility model;

[0031] Figure 5 It is a top view schematic diagram of the positional relationship between the color conversion layer and the pixel unit of the utility model;

[0032] Figure 6 yes Figure 2 The preparation flow chart of the display chip shown;

[0033] Figure 7 It is a preparation flow chart of another solution of the display chip of the utility model;

[0034] Figure 8 yes Figure 4 The preparation flow chart of the display chip shown;

[0035] Fig. 9 It is a schematic diagram of the structure in which the N-type semiconductor layer in the pixel unit of the utility model is only partially roughened;

[0036] Fig.10 It is a schematic diagram of the arrangement of the second insulating layer on the pixel unit in the utility model;

[0037] Fig.11 It is a schematic diagram of the structure of a display chip provided with a cathode contact in the utility model;

[0038] Fig.12 It is a schematic diagram of the arrangement of bonding metal parts in the utility model;

[0039] Fig.13 It is another schematic diagram of the arrangement of the bonding metal parts in the utility model;

[0040] Fig.14 It is a schematic diagram of the arrangement of a cathode component in the utility model (top view);

[0041] Fig.15 It is a schematic diagram of another arrangement of the cathode component in the utility model (top view);

[0042] Fig.16 It is a schematic diagram of the local structure of the pixel unit after roughening treatment in the utility model;

[0043] Description of the Figures in the Specification:

[0044] 10. epitaxial layer; 101. filling hole; 102. light blocking material;

[0045] 20, driving wafer; 201, anode contact; 202, cathode contact; 203, insulating dielectric layer;

[0046] 30, pixel unit; 301, P-type semiconductor layer; 302, active layer; 303, N-type semiconductor layer; 3031, first surface; 3032, raised portion; 3033, N-type ohmic contact layer; 304, top surface; 305, side surface;

[0047] 40. first insulating layer; 401. opening;

[0048] 50, cathode member; 501, first connection end; 502, second connection end; 503, transition portion;

[0049] 60. color transfer layer; 601. first contact surface;

[0050] 70. Lens;

[0051] 80. Metal grid; 90. Second insulating layer; 100. Bonding metal member; 110. Compound semiconductor; 1101. Substrate. DETAILED DESCRIPTION

[0052] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention. Obviously, the embodiments described are only part of the embodiments of the present disclosure, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present disclosure and its application or use.

[0053] In the description of the present utility model, it should be understood that the terms "vertical", "upper", "lower", "top", "side", "inner", "outer" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present utility model. In addition, the terms "first" and "second" are used for descriptive purposes only, 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" and "second" may explicitly or implicitly include one or more of the features. In the description of the present utility model, unless otherwise specified, "multiple" means two or more.

[0054] The present embodiment provides a display chip based on monochrome color conversion and a preparation method thereof, so as to facilitate the processing of the color conversion structure and effectively ensure its structural stability and display quality, thereby better meeting production and use requirements.

[0055] The following will be combined Figure 2-Figure 16 , the structure of this embodiment is further described.

[0056] Embodiment 1

[0057] See also Figure 2-Figure 3 , this embodiment discloses a display chip based on monochrome color conversion, including a driving wafer 20, a pixel unit 30 and a color conversion layer 60;

[0058] The driver wafer 20 includes an anode contact 201 ; the driver wafer 20 may be a CMOS driver wafer 20 .

[0059] The pixel unit 30 is disposed on the driving wafer 20 and corresponds to the anode contact 201. The pixel unit 30 includes a P-type semiconductor layer 301, an active layer 302 and an N-type semiconductor layer 303 sequentially disposed along a first direction. The active layer 302 is used to emit light. The P-type semiconductor layer 301 is electrically connected to the corresponding anode contact 201 on the driving wafer 20, and the N-type semiconductor layer 303 is electrically connected to the cathode member 50.

[0060] like Figure 2 and Figure 5 As shown, 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 both located inside the color conversion layer 60 , and the cathode element 50 is at least partially located inside the color conversion layer 60 .

[0061] 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 side of the pixel unit 30 closest to the driving wafer 20 in the first direction, and the "top surface 304" refers to the side farthest from the driving wafer 20 in the first direction, and the "side surface 305" of the pixel unit 30 is the part located between the "top surface 304" and the "bottom surface" and connecting the "top surface 304" and the "bottom surface". Generally, the N-type semiconductor layer 303 is the farthest from the driving wafer 20 of the pixel unit 30 in the first direction, and the "top surface 304" of the pixel unit 30 is the upper surface of the N-type semiconductor layer 303. The P-type semiconductor layer 301 is the closest to the driving wafer 20 of the pixel unit 30 in the first direction, and the "bottom surface" of the pixel unit 30 is the lower surface of the P-type semiconductor layer 301.

[0062] It can be understood that the cathode component 50 is used to connect to the cathode of the driver wafer 20. Since the P-type semiconductor layer 301 is electrically connected to the corresponding anode contact 201 on the driver wafer 20, when the cathode component 50 is connected to the cathode of the driver wafer 20, the N-type semiconductor layer 303 is also electrically connected to the cathode of the driver wafer 20. At this time, a closed circuit is formed between the driver wafer 20 and the pixel unit 30, thereby driving the active layer 302 to emit light, thereby realizing the light-emitting operation of the pixel unit 30.

[0063] The color conversion layer 60 includes phosphor or quantum dots. When light passes through the color conversion layer 60, it will excite the phosphor to achieve color conversion through the quantum dots. For example, if the color conversion layer 60 is a mixture of quantum dots and photoresist (or silica gel), the color conversion layer 60 can change the wavelength of the light emitted by the pixel unit 30 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 a longer wavelength. Specifically, the blue light emitted by the pixel unit 30 can be converted into green light or red light, etc., or the purple light emitted by the pixel unit 30 can be converted into blue light, green light or red light, etc. The color conversion layer 60 can also be a mixture of phosphor and photoresist (or silica gel), which will not be repeated here.

[0064] In the above structure, the color conversion layer 60 is a whole covering all the pixel units 30 of the display chip and is arranged continuously, that is, the color conversion layer 60 is omnidirectional and continuous covering the entire pixel array area, and is non-discontinuous. On the basis of ensuring the color conversion effect, the aspect ratio of the color conversion layer 60 can be effectively reduced, which is more convenient for processing. It is not necessary to etch and fill each pixel unit 30 separately to form an independently separated color conversion layer 60, which simplifies the processing technology and makes the overall structure simpler. Since the above color conversion layer 60 can cover 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 of the side surface 305, which not only increases the thickness of the color conversion layer 60 and avoids light leakage and efficiency problems of color conversion, but also is more conducive to the miniaturization of the pixel size. At the same time, it effectively increases the fixing reliability and stability of the color conversion layer 60, so that the display quality of the chip can be guaranteed.

[0065] In some embodiments, the display chip further includes a lens 70 , which corresponds to the pixel unit 30 one by one and is located on the light output 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.

[0066] By setting the lens 70, a collimating structure can be introduced to better prevent the light crosstalk problem between the pixel units 30, that is, the color-converted light is collimated through the lens 70, thereby optimizing the crosstalk between pixels.

[0067] The surface of the lens 70 may be a smooth curved surface or an uneven curved surface composed of a plurality of step gradients.

[0068] In some embodiments, the contact surface between the color conversion layer 60 and the lens 70 is defined as a first contact surface 601. Figure 2 As shown, the focus of the lens 70 is located between the first contact surface 601 and the top surface 304 of the pixel unit, which can collimate the light that may cause crosstalk to the greatest extent, thereby improving the anti-crosstalk and light collimation effects.

[0069] 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 between the lens 70 and the color conversion layer 60 is the 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, and the distance between the center point of the first contact surface 601 and the vertex of the lens 70 is r3, then r1>r3≥r2. This solution makes the shape of the lens 70 closer to a half-rugby 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.

[0070] Furthermore, 1um≤r2≤40um, so as to better ensure the anti-crosstalk effect between pixel units.

[0071] In some embodiments, the cathode member 50 may be a transparent conductive film, and the cathode connection may be achieved directly 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, or the like.

[0072] In some other embodiments, all pixel units 30 are arranged in an array, a metal grid 80 is provided between two adjacent pixel units 30, and the cathode components 50 of two adjacent pixel units 30 are electrically connected to the metal grid 80 therebetween to achieve cathode current enhancement through the metal grid 80 and ensure the cathode connection effect.

[0073] Specifically, Figure 5 As shown, the pixel array may include at least 100 pixel units 30, and the specific number may be set according to actual needs and is not limited here.

[0074] The above method realizes cathode connection through "cathode component 50+metal grid 80", which can realize cathode current enhancement or be directly realized through metal grid 80. Metal grid 80 can be a single layer or multiple layers of materials such as Al, Ni, Ti, Cr, Pt, Au, etc. Specifically, metal grid 80 can be 300nmAl+100nm Ti+50nm Pt+1000nm Au.

[0075] Furthermore, the height of the pixel unit 30 along the first direction is h, and the height of the metal grid 80 along the first direction is L, then L≥0.1h, so as to better ensure the enhancement effect of the cathode current.

[0076] 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, 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.

[0077] Specifically, the height L of the metal grid 80 along the first direction is 200 nm to 5000 nm to better ensure the cathode current enhancement effect.

[0078] In some embodiments, the length D2 of the metal grid 80 along the second direction may be 0.2 um to 10 um, which can well balance the horizontal occupied space and current expansion, and is more conducive to the miniaturization of the chip while ensuring the current expansion.

[0079] In some embodiments, the angle k between the metal grid 80 and the driving unit is 90°±45°. Preferably, k≥90°, which is easier to implement in terms of process.

[0080] Furthermore, the minimum spacing between two adjacent lenses 70 in the second direction is D1, and the length of the metal grid 80 along the second direction is D2, then 0≤D1≤D2, wherein the second direction is perpendicular to the first direction. That is, the minimum spacing between two adjacent lenses 70 in the second direction is less than or equal to the length of the metal grid between the two. Through the above settings, the optical crosstalk phenomenon between pixels can be minimized. If D1>D2, the anti-crosstalk effect will be reduced.

[0081] The first direction generally refers to a direction away from the driving unit, and the second direction refers to a direction perpendicular to the first direction. In this document, "up, down" or "top, bottom" are all relative to the first direction.

[0082] In this embodiment, the periphery of the pixel unit 30 is covered with a first insulating layer 40, the first insulating layer 40 has an opening 401, the surface of the N-type semiconductor layer 303 away from the driving wafer 20 along the first direction is a first surface 3031, and the first surface 3031 is partially exposed at the opening 401, and the cathode component 50 of each pixel unit 30 is covered on the outside of the first insulating layer 40 and is electrically connected to the exposed portion of the first surface 3031.

[0083] The first insulating layer 40 can achieve insulation isolation between the P-type semiconductor layer 301 and the N-type semiconductor layer 303 inside the pixel unit 30 to avoid short circuit leakage between the two.

[0084] In some of the embodiments, the first surface 3031 has a plurality of protrusions 3032 , and the protrusions 3032 may be regularly distributed or randomly distributed to reduce the total reflection phenomenon in the light exiting area and improve the light extraction efficiency in the light exiting area.

[0085] Preferably, the length of the protrusion 3032 along the first direction and the second direction is 50nm to 800nm, and the second direction is perpendicular to the first direction; its size reaches nanometer level, which is more suitable for use in Micro-LED.

[0086] Furthermore, the lengths of the protrusions 3032 along the first direction and the second direction are both 80 nm to 250 nm.

[0087] In some embodiments, such as Fig.16 As shown, at least two protrusions 3032 have different shapes, which is more conducive to reducing the processing difficulty and improving the processing efficiency.

[0088] For example, Fig.16 As shown, the protrusion 3032 may be spherical, pyramidal or conical, and the pyramidal shape may be a hexagonal pyramid, a dodecagonal pyramid or the like.

[0089] Specifically, an alkali solution with a pH of 8 to 10 can be prepared by mixing a mixture of ammonium hydroxide and an organic amine, and the first surface 3031 can be roughened by soaking at 80° C. for 30 minutes. Fig.16 The protrusion 3032 shown has a mixed structure of sphere, hexagonal pyramid, dodecagonal pyramid, etc.

[0090] In some embodiments, such as Fig.14 and Fig.15 As shown, the cathode component 50 of each pixel unit 30 has a first connection terminal 501 and a second connection terminal 502, the first connection terminal 501 is electrically connected to the exposed portion of the corresponding first surface 3031, the shape of the first connection terminal 501 is adapted to the shape of the first surface 3031, and the second connection terminal 502 is used to connect to the cathode component 50 of the adjacent pixel unit 30.

[0091] For example, the first surface 3031 is uneven and has a plurality of protrusions 3032 , and the first connecting end 501 correspondingly has a plurality of grooves to adapt to the shape of the protrusions 3032 to achieve snap connection.

[0092] Furthermore, each cathode component 50 includes a plurality of circumferentially arranged first connection ends 501 , which may be located at the edges of the first surface 3031 , such as at exposed portions at two or four corners of the first surface 3031 , to better ensure the stability of electrical contact.

[0093] In some of the embodiments, at least two first connection terminals 501 in the cathode member 50 are connected via a transition portion 503, and the transition portion 503 of the cathode member 50 in the pixel unit 30 runs across the first surface 3031 to better ensure the stability of the cathode connection and to enhance cathode current conduction.

[0094] In some embodiments, such as Figure 2 As shown, 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 reduce the optical crosstalk between pixels and reduce the light leakage caused by insufficient thickness of the color conversion layer.

[0095] It can be understood that the height H of the color conversion layer 60 here refers to the distance between the lowest bottom surface of the color conversion layer 60 and the highest top surface 304 in the first direction, and the height h of the pixel unit 30 also 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.

[0096] Preferably, 30h≤H≤40h, and the crosstalk optimization effect is best within this range.

[0097] Further, the length H of the color conversion layer 60 along the first direction is 2 um to 100 um. For example, the color conversion layer 60 is formed by a mixture of phosphor and silica gel with H of 30 um to completely cover the pixel array, and the color conversion layer 60 is continuous in the entire pixel column area.

[0098] In some embodiments, the P-type semiconductor layer 301 in the pixel unit 30 is electrically connected to the corresponding anode contact 201 through an independent bonding metal member 100, and adjacent anode contacts 201 on the driver wafer 20 are isolated by an insulating dielectric layer 203. The anode contact 201 is a conductive metal.

[0099] like Fig.12 and Fig.13 As shown, the above-mentioned independent bonding metal parts 100 can be prepared when preparing the compound semiconductor 110 to obtain a patterned bonding metal part 100, and the insulating dielectric layer 203 can be filled between the bonding metal parts 100 of the compound semiconductor 110. Similarly, each anode contact 201 can also be prepared when preparing the driver wafer 20. After that, the compound semiconductor 110 and the driver wafer 20 are bonded. The size of the bonding metal part 100 or the anode contact 201 prepared before bonding can be larger, and the size of the bonding metal part 100 or the anode contact 201 can be further patterned after subsequent bonding to reduce the size. This method obtains a large piece of bonding metal part 100 by patterning the bonding layer before bonding, which is more conducive to stress control during the bonding process and avoids excessive warping. At the same time, compared with the design of the entire bonding layer, there is less metal on the wafer after patterning, especially precious metals that can be recycled, which is lower in cost. At the same time, the metal on the non-entire surface can use the metal-free area to arrange the alignment marks required for bonding, exposure and other processes on the driving wafer 20 in advance, without being blocked by metal, and the process is easier to implement. In addition, the alignment and bonding accuracy requirements of this large-scale patterning are greatly reduced, and it is also easier to implement.

[0100] Furthermore, the length of the bonding metal part 100 along the second direction may be greater than the length of a single anode contact 201 along the second direction, so that the bonding metal part 100 has a larger size, which is conducive to reducing the alignment and bonding accuracy of the bonding metal part 100 and the anode contact 201 and is easier to implement.

[0101] In some of the embodiments, a P-type ohmic contact layer made of a conductive material, such as a transparent conductive film, may 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 may be located between the P-type semiconductor layer 301 and the bonding metal member 100.

[0102] In some of the embodiments, a reflective metal layer may also be disposed on the P-type ohmic contact layer, and the reflective metal layer is located between the P-type ohmic contact layer and the bonding metal member 100 .

[0103] In some embodiments, the N-type semiconductor layer of each pixel unit 30 is electrically connected to the cathode member 50 via the N-type ohmic contact layer 3033 .

[0104] In some embodiments, such as Fig.11 As shown, the driving wafer 20 is also provided with a cathode contact 202 , and the cathode contact 202 and the anode contact 201 are both conductive metals. Adjacent anode contacts 201 and cathode contacts 202 are isolated by an insulating medium layer 203 , and the cathode member 50 of each pixel unit 30 is electrically connected to the corresponding cathode contact 202 .

[0105] In one embodiment, the shape of the pixel unit 30 includes but is not limited to a circle, a trapezoid, a hexagon or an octagon.

[0106] In some embodiments, the angle θ between the pixel unit 30 and the driving wafer 20 is 45° to 90°, and the length F of the pixel unit 30 in the second direction is 1 um to 100 um.

[0107] The display chip in the above embodiment may be a Micro-LED chip, a Micro-Laser chip, or other optoelectronic devices.

[0108] The shape of the pixel unit can be circular, trapezoidal, hexagonal or octagonal, etc.

[0109] like Figure 6 As shown, this embodiment also discloses a method for preparing a display chip based on monochrome color conversion, comprising the following steps:

[0110] 1) preparing a driver wafer 20 so that the driver wafer 20 includes an anode contact 201; and simultaneously preparing the compound semiconductor 110;

[0111] The driving wafer 20 may be a CMOS driving wafer 20 .

[0112] 2) If Figure 6 In the middle ac stage, the compound semiconductor 110 is connected to the driving wafer 20, and the compound semiconductor 110 is processed to form a pixel unit 30 corresponding to the anode contact 201; the pixel unit 30 includes a P-type semiconductor layer 301, an active layer 302 and an N-type semiconductor layer 303 arranged in sequence along the first direction, and the P-type semiconductor layer 301 is electrically connected to the corresponding anode contact 201 on the driving wafer 20;

[0113] 3) If Figure 6In the middle e stage, the N-type semiconductor layer 303 of each pixel unit 30 is electrically connected to the corresponding cathode element 50;

[0114] 4) Prepare the color transfer layer 60, such as Figure 6 In the middle f stage, 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.

[0115] In some embodiments, such as Figure 6 In the middle g stage, after the preparation of the color conversion layer 60 is completed, a lens 70 needs to be formed on the color conversion layer 60, so that the lens 70 and the pixel unit 30 correspond one to one and are located on the light output path of the corresponding pixel unit 30. The lens 70 is located on the side of the color conversion layer 60 away from the driving wafer 20 along the first direction, so as to achieve light collimation through the lens 70 and reduce optical crosstalk.

[0116] The compound semiconductor 110 generally refers to a compound formed by two or more elements. For example, the compound semiconductor here is mainly a light-emitting diode epitaxial material, such as an InGaN ternary material system or an AlGaInP quaternary material system.

[0117] 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 in a direction away from the substrate 1101; the active layer 302 is used to emit light;

[0118] Taking the Micro-LED field as an example, some compound materials involved in this embodiment are shown in Table 1. In some practical applications, the film layer of the compound semiconductor will be more complicated, or there will be cross-use of materials, mainly including P-type semiconductor layer materials, N-type semiconductor layer materials and an active layer (MQW active quantum well) sandwiched between the two:

[0119] Table 1. Materials of various compound films

[0120]

[0121]

[0122] In some embodiments, the method of connecting the compound semiconductor 110 and the driving wafer 20 and processing the compound semiconductor 110 to form a pixel unit 30 corresponding to the anode contact 201 includes:

[0123] Step S1), as Figure 6In the middle a stage, the P-type semiconductor layer 301 of the compound semiconductor 110 and the anode contact 201 of the driving wafer 20 are electrically connected;

[0124] Step S2), remove the substrate 1101, see Figure 6 Middle b stage;

[0125] Step S3), as Figure 6 In stage c, the compound semiconductor 110 is etched to obtain the pixel unit 30 corresponding to the anode contact 201.

[0126] Furthermore, the compound semiconductor 110 and the driver wafer 20 are connected by thermocompression bonding. Specifically, in step S1), the surfaces of the compound semiconductor 110 and the driver wafer 20 are activated by argon or nitrogen plasma and then roughly aligned with the wafer contour for thermocompression bonding. The bonding temperature is 310°C and the pressure is 5000 kg. The bonding metal part 100 and the anode contact 201 and the layers thereof are respectively integrated together by bonding.

[0127] Furthermore, if Figure 6 In the middle stage d, before the N-type semiconductor layer 303 of each pixel unit 30 is electrically connected to the corresponding cathode component 50, a first insulating layer 40 is required to be coated on the outside of the pixel unit 30, and an opening 401 is set on the first insulating layer 40. The surface of the N-type semiconductor layer 303 away from the driving wafer 20 along the first direction is the first surface 3031, so that the first surface 3031 is partially exposed at the opening 401, and then the cathode component 50 is coated on the outside of the first insulating layer 40, and the cathode component 50 of each pixel unit 30 is electrically connected to the exposed portion of the first surface 3031, thereby realizing electrical connection between the cathode component and the N-type semiconductor layer 303.

[0128] The first insulating layer 40 is made of one or more materials such as aluminum oxide, silicon oxide, and silicon nitride.

[0129] When preparing the first insulating layer 40 , a whole-surface coating method may be adopted, and then a patterned opening is made on the top surface 304 of the pixel unit 30 . The opening may partially open the top surface 304 of the pixel, and may be realized by a single opening or multiple openings.

[0130] In some of the embodiments, the first surface 3031 of the N-type semiconductor layer 303 needs to be roughened before the first insulating layer 40 is coated on the outside of the pixel unit 30. The roughening method includes: treating the first surface 3031 by plasma dry etching, high-temperature acid solution corrosion or high-temperature alkaline solution corrosion, so that a plurality of protrusions 3032 are formed on the first surface 3031. Compared with traditional micron-level roughening or coarsening, the protrusions 3032 formed by this method have a size of 50nm to 800nm.

[0131] For example, the size of the protrusion 3032 obtained by treating the first surface with a mixed alkali solution of high-temperature sodium hydroxide (NaOH) and hydrogen peroxide (H2O2) is 80nm to 250nm.

[0132] Preferably, Fig. 9 As shown, the above-mentioned roughening treatment can be local roughening, which is used to control better ohmic contact and avoid voltage anomalies caused by the roughened structure.

[0133] In one embodiment, if Figure 4 As shown, the roughening treatment may not be performed before the first insulating layer 40 is coated on the outside of the pixel unit 30. A transparent conductive film layer may be provided on the first surface 3031 of the N-type semiconductor layer 303 as an N-type ohmic contact layer 3033, so as to achieve electrical connection with the cathode member 50 through the N-type ohmic contact layer 3033. The specific preparation process is shown in Figure 8 .

[0134] In one embodiment, when preparing the driver wafer 20, adjacent anode contacts 201 on the driver wafer 20 are isolated by an insulating dielectric layer 203. When preparing the compound semiconductor 110, a plurality of independent bonding metal parts 100 are arranged on the P-type semiconductor layer 301 of the compound semiconductor 110. The bonding metal parts 100 correspond to the pixel units 30 one by one, and the number of the bonding metal parts 100 is consistent with the final number of the pixel units 30. Thereafter, when the compound semiconductor 110 and the driver wafer 20 are hot-pressed bonded, the bonding metal parts 100 and the corresponding anode contacts 201 are electrically connected.

[0135] Furthermore, the above-mentioned bonding metal part 100 can be a single-layer structure made of one of the materials selected from aluminum (Al), gold (Au), and copper (Cu), or a stacked-layer structure of materials such as nickel (Ni), gold (Au), and copper (Cu) and tin (Sn), or a bonding layer structure of gold (Au) and indium (In), germanium (Ge), or silicon (Si). The bonding metal part 100 can be obtained by etching after plating, or by plating after pattern masking. It is preferred to obtain the bonding metal part by plating after pattern masking to facilitate the recovery of precious metals and reduce costs.

[0136] The above method obtains an independent bonding metal part 100 by patterning the bonding layer before bonding, which is more conducive to stress control in the subsequent bonding process and avoids deformation of the wafer. Compared with the design of the entire bonding layer, there is less metal on the wafer after patterning, which is conducive to metal recycling and lower cost. It is also conducive to reducing the alignment and bonding accuracy and is easier to achieve.

[0137] Specifically, in one implementation, the bonding metal component 100 includes 1nm of adhesion layer metal Cr+50nm of reflection layer metal Al+50nm of adhesion metal Ti+40nm of bonding metal Ni+100nm of bonding metal Sn+10nm of bonding metal Au.

[0138] In some embodiments, when a plurality of bonding metal parts 100 are prepared on the compound semiconductor 110, an insulating dielectric layer 203 is also filled between adjacent bonding metal parts 100 to achieve insulation isolation. The dielectric layer can be inorganic materials such as silicon oxide, silicon nitride, carbon-doped silicon nitride, or nitrogen-doped amorphous carbon, or organic materials such as polyimide. Similarly, an insulating dielectric layer 203 can also be filled between adjacent anode contacts 201 of the driver wafer 20.

[0139] In some embodiments, during preparation, such as Figure 6 In the middle e stage, when the N-type semiconductor layer 303 of each pixel unit 30 is electrically connected to the corresponding cathode component 50, a metal grid 80 is also set between two adjacent pixel units 30, and the cathode components 50 of the two adjacent pixel units 30 are electrically connected to the metal grid 80, and the color conversion layer 60 at least covers a portion of the metal grid 80 to achieve cathode current enhancement through the metal grid 80.

[0140] Embodiment 2

[0141] The main difference between this embodiment and implementation 1 is that: Figure 7 As shown in stage a, the periphery of the pixel unit 30 is coated with a first insulating layer 40, the first insulating layer 40 has an opening 401, the surface of the N-type semiconductor layer 303 away from the driving wafer 20 along the first direction is a first surface 3031, and the first surface 3031 is fully exposed at the opening 401, and the cathode component 50 of each pixel unit 30 is coated on the outside of the first insulating layer 40 and electrically connected to the exposed portion of the first surface 3031.

[0142] When preparing the first insulating layer 40 , a whole-surface coating method may be adopted, and then a patterned opening is performed on the top surface 304 of the pixel unit 30 . The opening can completely open the top surface 304 of the pixel unit 30 .

[0143] The preparation method of the display chip of this embodiment is shown in Figure 7 The basic steps are substantially 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 in detail here.

[0144] In this embodiment, the cathode connection can be connected only by the cathode member 50, and the cathode member 50 can be a transparent conductive film or a Figure 7In the cathode connection mode of “cathode element 50 + metal grid 80 ” shown in stage d, a metal grid 80 is disposed between adjacent pixel units 30 , so that the metal grid 80 and the adjacent cathode element 50 are electrically connected.

[0145] Embodiment 3

[0146] The main difference between this embodiment and implementation 1 is that: Fig.10 As shown, the periphery of the pixel unit 30 is also 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 .

[0147] The second insulating layer 90 is used to block the contact between the organic material in the subsequent color conversion layer 60 and the pixel unit 30 structure to avoid damage to the cathode connection structure. For example, when the color conversion layer 60 contains trace amounts of acid, it will corrode some metal grid 80 materials.

[0148] The second insulating layer 90 is made of one or more materials such as aluminum oxide, silicon oxide, and silicon nitride.

[0149] The second insulating layer 90 is prepared after the cathode component 50 is prepared, so that the second insulating layer 90 covers the cathode component 50 .

[0150] In the display chips prepared by the above-mentioned embodiments, the color conversion layer integrally covers all the pixel units of the display chip and is arranged continuously, which is easier to process and simplifies the processing technology. Not only does it make the overall structure simpler, it can also avoid color conversion light leakage and efficiency problems, and is more conducive to the miniaturization of pixel size. At the same time, it also effectively increases the fixing reliability and stability of the color conversion layer, so that the display quality of the chip can be guaranteed, achieving higher brightness and being more suitable for Micro-LED use.

[0151] All the above-mentioned optional technical solutions can be combined in any way to form optional embodiments of the present invention, that is, any multiple embodiments can be combined to meet the needs of different application scenarios. They are all within the protection scope of this application and will not be described one by one here.

[0152] It should be noted that the above embodiments are merely examples for the purpose of clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

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, the pixel unit is arranged on the driving wafer and corresponds to the anode contact, the pixel unit comprises 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 the cathode member; A color conversion layer covers all of the pixel units and is arranged continuously, and a top surface and at least a portion of a side surface of the pixel unit are located inside the color conversion layer.

2. The display chip based on monochrome color conversion according to claim 1, characterized in that: It also includes a lens, which corresponds to the pixel unit one by one and is located on the light output path of the corresponding pixel unit. The lens is located on a side of the color conversion 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 conversion layer and the lens is a first contact surface, and the focus 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 conversion 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, and 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, a metal grid is arranged between two adjacent pixel units, and the cathode parts of the two adjacent pixel units are electrically connected to the metal grid.

6. The display chip based on monochrome color conversion according to claim 5, characterized in that: It has 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 grid along the second direction is D2, then 0≤D1≤D2.

7. The display chip based on monochrome color conversion according to claim 1, characterized in that: The periphery of the pixel unit is covered with a first insulating layer, the first insulating layer has an opening, the surface of the N-type semiconductor layer away from the driving wafer along the first direction is the first surface, the first surface is partially or fully exposed at the opening, and the cathode component 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 a plurality of 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: The cathode component of each pixel unit has a first connection end and a second connection end, the first connection end is electrically connected to the exposed portion of the first surface, the shape of the first connection end is adapted to the shape of the first surface, and the second connection end is used to connect to the cathode component 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 connecting ends arranged in a circumferential direction.

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 component are connected via a transition portion, and the transition portion of the cathode component in the pixel unit crosses above the first surface.

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

Images