Stepped seed-based microlens

Abstract

The utility model discloses a micro lens based on a step seed, and relates to the technical field of semiconductors. The micro lens comprises a step seed structure, the step seed structure comprises a bottom plane layer and a top seed layer arranged on the bottom plane layer, and the length of the top seed layer is smaller than that of the bottom plane layer, so that a step difference is formed between the top seed layer and the bottom plane layer; the micro-lens shell layer is arranged on the periphery of the step seed structure, the micro-lens shell layer is made of an inorganic transparent material, and the micro-lens shell layer protrudes in the direction away from the bottom plane layer. On the basis of the device construction scheme provided by the invention, the shape of the micro-lens shell layer meeting the requirement can be formed on the basis of the designed step seed structure, the process is relatively simple, and the yield is guaranteed.

Description

[0001] This application claims priority to Chinese Patent Application No. 202323345786.4, filed on December 8, 2023, entitled "Micro-lens based on step seed", the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0002] The utility model relates to the technical field of semiconductor, especially to a micro-lens based on step seed. BACKGROUND

[0003] As an important optical element, micro-lenses have the characteristics of small volume, light weight and high integration, attracting a lot of attention.

[0004] With the development of the semiconductor industry, a series of micro-lens preparation schemes have emerged. Traditional micro-lens preparation schemes include reflow, etching, printing, laser direct writing, point wetting, nano-imprinting, etc. In the above-mentioned traditional micro-lens preparation schemes, the process is relatively complicated, which can easily lead to yield problems. In order to simplify the preparation of micro-lenses, micro-lenses can be prepared by deposition, and the overall process of deposition is relatively simple.

[0005] However, if deposition is directly performed on the outer surface of the pixel unit, for example, chemical vapor deposition, a suitable micro-lens shape cannot be obtained. Therefore, how to construct the device to facilitate obtaining a micro-lens with a shape that meets the requirements during deposition needs to be provided. SUMMARY

[0006] The utility model aims at providing a micro-lens based on step seed, which can form a micro-lens shell layer that meets the shape requirements on the basis of the step seed structure, and the process is relatively simple, with yield guarantee.

[0007] To achieve the above-mentioned utility model purposes, the utility model provides the following technical scheme:

[0008] In this application, a micro-lens based on step seed is provided, which comprises:

[0009] A step seed structure, which comprises a bottom plane layer and a top seed layer arranged above the bottom plane layer, and the length of the top seed layer is less than the length of the bottom plane layer, so that a step difference is formed between the top seed layer and the bottom plane layer;

[0010] A micro-lens shell layer arranged around the outer periphery of the step seed structure, the micro-lens shell layer is an inorganic transparent material, and the micro-lens shell layer is convex in the direction away from the bottom plane layer.

[0011] In a possible implementation, the step seed structure is a pixel structure, and the pixel structure comprises a pixel unit and a CMOS layer at the bottom of the pixel unit.

[0012] At least one top layer in the pixel structure is used as the top seed layer, and at least one bottom layer in the pixel structure is used as the bottom planar layer.

[0013] In a possible implementation, the top seed layer comprises a compound pixel layer in the pixel unit, and the bottom planar layer comprises an ohmic layer, a bonding layer and the CMOS layer in the pixel unit.

[0014] Or;

[0015] The top seed layer comprises a compound pixel layer, an ohmic layer and a bonding layer in the pixel unit, and the bottom planar layer comprises a CMOS layer at the bottom of the pixel unit.

[0016] In a possible implementation, the step seed structure is a pixel structure with a filling layer, and the pixel structure with the filling layer comprises a pixel unit, a CMOS layer at the bottom of the pixel unit, and a filling layer at the top of the pixel unit, wherein the filling layer is made of a high-temperature-resistant organic material or an inorganic medium material.

[0017] At least one top layer in the pixel structure with the filling layer is used as the top seed layer, and at least one bottom layer in the pixel structure with the filling layer is used as the bottom planar layer.

[0018] In a possible implementation, the top seed layer comprises the filling layer in the pixel structure with the filling layer, and the bottom planar layer comprises the pixel unit, the CMOS layer in the pixel structure with the filling layer.

[0019] In a possible implementation, the filling layer gradually decreases in size in a direction away from the CMOS layer. In a possible implementation, the filling layer comprises a first filling layer above the top of the pixel unit and a second filling layer above the first filling layer, and the length of the second filling layer is smaller than that of the first filling layer. The top seed layer comprises the second filling layer in the pixel structure with the filling layer, and the bottom planar layer comprises the first filling layer, the pixel unit and the CMOS layer in the pixel structure with the filling layer.

[0020] In a possible implementation, the central axis of the filling layer is aligned with the central axis of the pixel unit.

[0021] In a possible implementation, the pixel unit further comprises a passivation layer covering the sidewall.

[0022] In a possible implementation manner, the surface of the passivation layer and the top surface of the pixel unit are further covered with a common cathode layer.

[0023] In a possible implementation manner, the step difference is between 0.5 μm and 10 μm.

[0024] In a possible implementation manner, the bottom diameter of the top seed layer is between 0.5 μm and 10 μm.

[0025] In a possible implementation manner, the ratio of the step difference to the bottom diameter of the top seed layer is between 0.5 and 3.

[0026] In a possible implementation manner, the height of the microlens shell layer is 0.5 times to 3 times the diameter of the microlens shell layer.

[0027] In a possible implementation manner, the diameter of the microlens shell layer is 0.8 to 1 times the center distance of adjacent pixel units.

[0028] In a possible implementation manner, the bottom diameter of the top seed layer is 0.4 to 0.8 times the center distance of adjacent pixel units.

[0029] In a possible implementation manner, the shape of the top seed layer comprises:

[0030] cylindrical, prism, cone, pyramid.

[0031] In a possible implementation manner, the shape of the microlens shell layer comprises: hemispherical, semi-olive ball.

[0032] Compared with the prior art, the present application has the following beneficial effects:

[0033] In the device construction, the step seed structure is formed, the step seed structure comprises a bottom plane layer and a top seed layer arranged on the bottom plane layer, and the length of the top seed layer is less than the length of the bottom plane layer, so that a step difference is formed between the top seed layer and the bottom plane layer, and a microlens shell layer is formed on the step seed structure, the microlens shell layer can be naturally protruded in the direction away from the bottom plane layer based on the arrangement of the step seed, and the required microlens is obtained.

[0034] Further, the microlens shell layer formed in situ is an inorganic transparent material, which is more resistant to high temperature and mechanical deformation than organic materials.

[0035] Further, the size and morphology of the microlens are controlled through the design of the step seed structure, without the need for separate preparation of a stamping template or the like, and the operation is convenient for mass production. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 is a structural schematic diagram of a microlens provided in an embodiment of the present application;

[0037] Figure 2 is a structural schematic diagram of a microlens provided in an embodiment of the present application;

[0038] Figure 3 is a structural schematic diagram of a microlens provided in an embodiment of the present application;

[0039] Figure 4 is a structural schematic diagram of a microlens provided in an embodiment of the present application;

[0040] Figure 5 is a structural schematic diagram of a pixel unit provided in an embodiment of the present application;

[0041] Figure 6 is a structural schematic diagram of a pixel unit provided in an embodiment of the present application;

[0042] Figure 7 is a structural schematic diagram of a filled pixel unit provided in an embodiment of the present application;

[0043] Figure 8 is a structural schematic diagram of a filled pixel unit provided in an embodiment of the present application;

[0044] Figure 9 is a structural schematic diagram of a filled pixel unit provided in an embodiment of the present application;

[0045] Figure 10 is a structural schematic diagram of a pixel unit provided in an embodiment of the present application;

[0046] Figure 11 is a method flow chart of a preparation method of a microlens provided in an embodiment of the present application;

[0047] Figure 12 is a schematic diagram of a light-emitting parameter of a microlens-free structure provided in an embodiment of the present application;

[0048] Figure 13 is a schematic diagram of a light-emitting parameter of a microlens structure provided in an embodiment of the present application. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0050] 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 convenience of describing 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 a limitation of 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 the technical features indicated. Therefore, the features limited by "first", "second" can be explicitly or implicitly included one or more features. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0051] In the description of the present application, it should be noted that, unless otherwise specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0052] In the embodiments of the present application, a technical scheme is proposed, which forms a microlens shell layer by depositing inorganic oxide or nitrogen oxide guided by a step seed structure. The microlens shell layer can form a desired shape based on the design of the step seed structure.

[0053] First, the specific structure of the microlens proposed in the present application is described.

[0054] The embodiments of the present application provide a microlens based on a step seed (hereinafter referred to as a microlens), as shown in Figure 1 The microlens includes:

[0055] The stepped seed structure comprises a bottom flat layer and a top seed layer arranged on the bottom flat layer, and the length of the top seed layer is less than the length of the bottom flat layer, so that a step difference is formed between the top seed layer and the bottom flat layer; a microlens shell layer arranged around the periphery of the stepped seed structure, the microlens shell layer is an inorganic transparent material, and the microlens shell layer protrudes in a direction away from the bottom flat layer.

[0056] In the embodiments of the present application, the formation of the microlens utilizes a stepped seed structure, which refers to a seed structure in a stepped style, which can be divided into a bottom flat layer and a top seed layer arranged on the bottom flat layer. Since the length of the top seed layer is less than the length of the bottom flat layer, the two layers form a stepped style with a step difference.

[0057] Based on the design of the stepped seed structure, chemical vapor deposition (CVD) is performed with the top seed layer as the center to in-situ grow a microlens shell layer of inorganic transparent material. Due to the presence of the step difference, the thickness of the shell layer grown in-situ from the top seed layer is obviously thicker than the thickness of the shell layer grown in-situ from both sides, so that the microlens shell layer naturally protrudes in a direction away from the bottom flat layer, obtaining the required protruding microlens shell layer.

[0058] Further, the ratio of the step difference to the bottom diameter of the top seed layer is between 0.5 and 3. Under the design that the ratio of the step difference to the bottom diameter of the top seed layer is between 0.5 and 3, the protrusion of the microlens shell layer also adapts to this limitation, forming the required protruding shape.

[0059] The microlens shell layer can be specifically an inorganic transparent medium layer material such as silicon oxide, silicon nitride, aluminum oxide, etc. The thickness of the microlens made based on the stepped seed can be equal to the thickness of the top seed layer plus the thickness of the microlens shell layer.

[0060] It can be understood that since the top seed layer and the bottom flat layer can have different lengths at different heights, the length of the top seed layer being less than the length of the bottom flat layer can specifically refer to the longest length of the top seed layer being less than the shortest length of the bottom flat layer.

[0061] The step difference is between 0.5 μm and 10 μm. Within this range, a microlens shell layer with a required height can be formed.

[0062] The bottom diameter of the top seed layer is between 0.5 μm and 10 μm. Within this range, a microlens shell layer with a required surface width can be formed.

[0063] Further, the bottom diameter of the top seed layer is 0.4 to 0.8 times the distance between the centers of adjacent pixel units, so that a matching microlens shell layer is obtained based on the top seed layer in this size range, which can correspond to each pixel unit one by one, and can also coat the pixel units, achieving a better optical collimation effect.

[0064] The step seed structure can be formed by a single pixel unit, as shown in Figure 2 As shown, the pixel structure including the pixel unit and the CMOS layer is used to form the step seed structure to make the microlens; or the pixel structure filled by the filling layer can be used to form the step seed structure to make the microlens. The filling layer can be a high-temperature-resistant organic material (≥200°C) such as SU8, silica gel, polyimide, etc., or an inorganic medium material such as silicon oxide, etc. Figure 3 Or Figure 4 As shown, the pixel structure filled by the filling layer is used to form the step seed structure to make the microlens.

[0065] In a possible implementation, the step seed structure is a pixel structure; at least one top layer in the pixel structure is used as a top seed layer, and at least one bottom layer in the pixel structure is used as a bottom flat layer.

[0066] In the implementation, the step seed structure is formed by a single pixel structure, at least one top layer in the pixel structure is used as a top seed layer, and at least one bottom layer in the pixel structure is used as a bottom flat layer.

[0067] Further, on the basis of the above implementation, the top seed layer includes a compound pixel layer in the pixel unit, and the bottom flat layer includes an ohmic layer, a bonding layer, and a CMOS layer at the bottom of the pixel unit; or the top seed layer includes a compound pixel layer, an ohmic layer, and a bonding layer in the pixel unit, and the bottom flat layer includes a CMOS layer at the bottom of the pixel unit.

[0068] That is, as shown in Figure 5 And Figure 6 The pixel unit includes a compound pixel layer, an ohmic layer, and a bonding layer, and the pixel unit and the CMOS layer form a pixel structure. When the step seed structure is formed by a single pixel structure, one possible way is that, as shown in Figure 5 The compound pixel layer in the pixel unit is patterned and etched as a top seed layer, and other layers in the pixel unit, i.e., an ohmic layer, a bonding layer, and a CMOS layer at the bottom, are used as a bottom flat layer; another possible way is that, as shown in Figure 6As shown, the compound pixel layer and the bonding layer in the pixel unit are patterned and etched to form an entirety, and the entirety is used as the top seed layer, and the other layers in the pixel structure, i.e., the CMOS layer, are used as the bottom planar layer. It can be understood that the step seed structure is formed by this way, and the implementation is relatively simple.

[0069] In a possible implementation, the step seed structure is a pixel structure with a filling layer composed of the pixel unit, the filling layer filled on the top of the pixel unit, and the CMOS layer on the bottom of the pixel unit, and the filling layer is made of high-temperature-resistant organic material or inorganic medium material; at least one top layer in the pixel structure with the filling layer is used as the top seed layer, and at least one bottom layer in the pixel structure with the filling layer is used as the bottom planar layer.

[0070] In the implementation, as shown in Figure 7 the high-temperature-resistant organic material or inorganic medium material (such as silicon oxide) is filled on the top of the prepared pixel unit to combine into the pixel structure with the filling layer, the pixel structure with the filling layer has the step seed structure, at least one top layer in the pixel structure with the filling layer is used as the top seed layer, and at least one bottom layer in the pixel structure with the filling layer is used as the bottom planar layer.

[0071] Further, on the basis of the implementation, the top seed layer includes the filling layer, and the bottom planar layer includes the pixel unit and the CMOS layer. In addition, the filling layer can gradually decrease in size in a direction away from the CMOS layer, so that the corresponding microlens shell layer can have a convex shape. In addition, the central axis of the filling layer and the central axis of the pixel unit are aligned, so that the central axis of the subsequent microlens shell layer can be aligned with the central axis of the final pixel unit, so as to better realize the function of the microlens shell layer.

[0072] Further, the filling layer includes a first filling layer above the top of the pixel unit and a second filling layer above the first filling layer, and the length of the second filling layer is less than the length of the first filling layer; the top seed layer includes the second filling layer in the pixel unit after filling, and the bottom planar layer includes the first filling layer, the pixel unit, and the CMOS layer in the pixel unit after filling. In addition, the central axis of the first filling layer, the central axis of the second filling layer, and the central axis of the pixel unit are aligned, so that the central axis of the subsequent microlens shell layer can be aligned with the central axis of the final pixel unit, so as to better realize the function of the microlens shell layer.

[0073] That is, when the step seed structure is formed by the pixel unit after filling through the filling layer, one possible way is as shown in Figure 8As shown, the filling layer is patterned to have a length smaller than the length of the top of the pixel unit, the filling layer is used as the top seed layer, and the pixel unit and the CMOS layer are used as the bottom planar layer. Figure 8 The microlens prepared by the corresponding stepped seed structure is as shown in Figure 3 As shown, the filling layer is patterned to have a length smaller than the length of the top of the pixel unit, the filling layer is used as the top seed layer, and the pixel unit and the CMOS layer are used as the bottom planar layer. Figure 9 As shown, the filling layer is patterned to have a length smaller than the length of the top of the pixel unit, the filling layer is used as the top seed layer, and the pixel unit and the CMOS layer are used as the bottom planar layer. Figure 9 The microlens prepared by the corresponding stepped seed structure is as shown in Figure 4 It can be understood that, by forming the stepped seed structure in this way, the shape, diameter, height, and other related structure parameters of the top seed layer are not limited by the shape of the pixel unit, and can be more flexibly controlled to obtain the required microlens shell layer based on the top seed layer.

[0074] Further, the center distance between two adjacent pixel units is defined as Pitch, and in this design in which the filling layer is used as the top seed layer, the projection diameter of the top seed layer on the CMOS layer can be controlled to be 0.4-0.8 times the Pitch, and the height is controlled to be 0.5-3 times the diameter of the top seed layer, so that the final microlens shell diameter is controlled to be 0.8-1 times the Pitch, and the height of the microlens shell is 0.5-3 times the diameter of the microlens shell, thereby obtaining the required microlens shell layer.

[0075] It can be understood that, as shown in the above two implementation manners, the stepped seed structure required by the present application can be implemented by a conventional stepped difference scheme, for example, the organic material such as SU8, silica gel, and polyimide can be directly patterned by photolithography, and the high-temperature-resistant organic material can be formed by inorganic material etching, for example, the compound pixel layer to be formed and the inorganic medium material to be subsequently grown. The microlens prepared by the stepped seed scheme does not need to involve complex processes such as melting, imprinting, and laser direct writing, and does not need to go through the process of etching after the traditional melting microlens topography mask, and does not need to ensure that the melting and etching consistency is very high. The process is simple and has a high yield. In addition, compared with the seed structure based on other shapes, such as a hemispherical seed structure, the microlens prepared by the stepped seed scheme does not need to pass through a high-temperature-resistant mask layer to a hemispherical shape or adjust the etching process to control the hemispherical etching, and therefore, the control precision is higher, the process is simple, and the feasibility is higher.

[0076] In a possible implementation manner, the pixel unit further includes a passivation layer covering the sidewall.

[0077] In the implementation manner, as Figure 10As shown, a passivation layer is coated on the sidewall surface of the pixel unit to passivate and protect the pixel unit. The passivation layer can be a single layer or a stack of layers of dielectric layers such as aluminum oxide, silicon nitride, silicon oxide, etc.

[0078] In a possible implementation, the surface of the passivation layer and the top surface of the pixel unit are further coated with a common cathode layer.

[0079] In the implementation, as shown, Figure 10 a common cathode layer is further coated on the surface of the passivation layer and the top surface of the pixel unit to complete the preparation of the common cathode of the pixel unit. The common cathode layer can be a transparent conductive film, which can be one or a combination of ITO (Indium Tin Oxide) film, AZO (Antimony doped Zinc Oxide) film, ATO (Antimony doped Tin Oxide) film, and FTO (Fluorine doped Tin Oxide) film. The transparent conductive film can also be a metal-doped ITO formed by annealing after plating a thin metal (such as Al, Au, Ag) on the surface of the ITO, to enhance the current transmission capability of the common cathode layer.

[0080] In a possible implementation, the shape of the top seed layer includes a cylindrical shape, a prism shape, a conical shape, and a polygonal pyramid shape. That is, the shape of the top seed layer in the stepped seed structure can be set as a cylindrical shape, a prism shape, a conical shape, a polygonal pyramid shape (such as a hexagonal pyramid, an octagonal pyramid, etc.), and the like according to the needs in the patterning process.

[0081] In a possible implementation, the shape of the microlens shell layer includes a hemispherical shape and a half-olive ball shape. That is, the microlens shell layer formed by in-situ growth can be set as a hemispherical microlens or a half-olive ball microlens shell layer according to the needs.

[0082] In summary, the microlens provided by the embodiments of the present application forms a stepped seed structure when the device is constructed. The stepped seed structure includes a bottom planar layer and a top seed layer arranged on the bottom planar layer, and the length of the top seed layer is less than the length of the bottom planar layer, so that a step difference is formed between the top seed layer and the bottom planar layer. Thus, a microlens shell layer is formed on the stepped seed structure, which naturally protrudes away from the bottom planar layer based on the setting of the stepped seed, to obtain the required microlens.

[0083] Further, the microlens shell layer formed by in-situ growth is an inorganic transparent material, which is more resistant to high temperature and mechanical deformation than an organic material.

[0084] Next, the microlens preparation method corresponding to the microlens described in the above embodiments is described.

[0085] The embodiment of the present application also provides a microlens preparation method, which is used for preparing the microlens as described in the above embodiment, and the method can comprise the following steps: Figure 11 The method can comprise the following steps:

[0086] Step 1110: preparing a stepped seed structure, the stepped seed structure comprising a bottom planar layer and a top seed layer arranged on the bottom planar layer, and the length of the top seed layer being less than the length of the bottom planar layer, so that a stepped difference is formed between the top seed layer and the bottom planar layer.

[0087] In this step, a stepped seed structure with a stepped difference is prepared, the stepped seed structure comprising a bottom planar layer and a top seed layer, and the length of the top seed layer being prepared to be less than the length of the bottom planar layer, so that a stepped difference is formed.

[0088] In a possible implementation, the step 1110 comprises:

[0089] (1) performing patterned etching on the pixel unit.

[0090] Specifically, for the pixel unit structure as shown in Figure 5 , Figure 6 , the compound pixel layer, the ohmic layer and the bonding layer are patterned and etched in sequence from top to bottom.

[0091] (2.1) taking the compound pixel layer in the patterned pixel unit as the top seed layer, and taking the ohmic layer, the bonding layer and the CMOS layer at the bottom of the patterned pixel unit as the bottom planar layer.

[0092] As shown in Figure 5 , in the design that the length of the compound pixel layer is less than the lengths of the ohmic layer, the bonding layer and the CMOS layer after patterned etching, the compound pixel layer in the patterned pixel unit is taken as the top seed layer, and the ohmic layer, the bonding layer and the CMOS layer at the bottom of the patterned pixel unit are taken as the bottom planar layer, so that the stepped seed structure is prepared.

[0093] (2.2) taking the compound pixel layer, the ohmic layer and the bonding layer in the patterned pixel unit as the top seed layer, and taking the CMOS layer at the bottom of the patterned pixel unit as the bottom planar layer.

[0094] As shown in Figure 6 , in the design that the length of the compound pixel layer, the ohmic layer and the bonding layer is less than the length of the CMOS layer after patterned etching, the compound pixel layer, the ohmic layer and the bonding layer in the patterned pixel unit are taken as the top seed layer, and the CMOS layer is taken as the bottom planar layer, so that the stepped seed structure is prepared.

[0095] In a possible implementation, step 1110 comprises:

[0096] (1) Graphically etching the pixel unit.

[0097] Specifically, for the pixel unit structure as shown in Figure 5 , Figure 6 , the compound pixel layer, the ohmic layer, the bonding layer and the CMOS layer are graphically etched in the order from top to bottom.

[0098] (2) Forming a filling layer by filling the top of the graphically etched pixel unit, and the filling layer adopts a high-temperature-resistant organic material or an inorganic medium material.

[0099] Specifically, the pixel unit is filled by a high-temperature-resistant organic material or an inorganic medium material (such as silicon oxide), and the filling is performed on the top of the pixel unit.

[0100] (3.1) The filling layer of the high-temperature-resistant organic material is graphically etched, or the filling layer of the inorganic medium material is graphically etched, so that the length of the graphically etched filling layer is less than the length of the top of the pixel unit, the filling layer is used as the top seed layer, and the pixel unit and the CMOS layer are used as the bottom plane layer.

[0101] As shown in Figure 7 , Figure 8 , for the filled pixel unit composed of the pixel unit and the filling layer, if the filling layer adopts the high-temperature-resistant organic material, the filling layer is graphically etched by photolithography, or if the filling layer adopts the inorganic medium material, the filling layer is graphically etched by etching, so that the length of the graphically etched filling layer is less than the length of the top of the pixel unit, the filling layer is used as the top seed layer, and the pixel unit and the CMOS layer are used as the bottom plane layer, thereby preparing the step seed structure.

[0102] (3.2) The filling layer of the high-temperature-resistant organic material is graphically etched, or the filling layer of the inorganic medium material is graphically etched, so that the graphically etched filling layer forms a first filling layer above the top of the pixel unit and a second filling layer above the first filling layer, and the length of the second filling layer is less than the length of the first filling layer, the second filling layer is used as the top seed layer, and the first filling layer, the pixel unit and the CMOS layer are used as the bottom plane layer.

[0103] As shown in Figure 7 , Figure 9As shown, for the filled pixel unit composed of the pixel unit and the filling layer, if the filling layer adopts high-temperature-resistant organic material, the filling layer is patterned by photolithography, if the filling layer adopts inorganic medium material, the filling layer is patterned by etching, so that the patterned filling layer is divided into a first filling layer and a second filling layer, the length of the second filling layer is less than the length of the first filling layer, the second filling layer is taken as a top seed layer, and the first filling layer, the pixel unit and the CMOS layer are taken as a bottom planar layer, so as to prepare a step seed structure.

[0104] In a possible implementation, after the pixel unit is patterned and etched in the above step, the method further includes the following steps: passivating the sidewall of the pixel unit to form a passivation layer; and coating a transparent conductive film on the surface of the passivation layer and the top surface of the pixel unit to form a common cathode layer.

[0105] In this step, after the pixel unit is patterned and etched, compound pixel sidewall passivation and common cathode current expansion are further introduced to complete the preparation of N-type ohmic contact and common cathode.

[0106] Step 1120: in-situ growth of a microlens shell layer around the step seed structure by chemical vapor deposition, the microlens shell layer protrudes away from the bottom planar layer, and the microlens shell layer is an inorganic transparent material.

[0107] In this step, by using the step seed structure prepared in advance as a guide, the deposited inorganic transparent material is naturally grown into a microlens structure by using PSG (phosphate glass), BPSG (boron phosphorus silicate glass) process or inorganic silicon oxide or nitrogen oxide prepared by using TEOS (tetraethoxysilane), TEPO (triethyl phosphate) and the like as a deposition source, which has the characteristic of fluidity.

[0108] In an embodiment, taking a Micro-LED micro display chip as an example, after in-situ growth of the microlens, the luminous intensity is increased by 80%, and the luminous angle is converged from 110° (as shown in Figure 12 without a microlens to 51° (as shown in Figure 13 with the in-situ grown microlens).

[0109] In a possible implementation, the step 920 includes: controlling the size and shape of the microlens shell layer formed by in-situ growth around the step seed structure by chemical vapor deposition through the step seed related parameters including the step difference and in-situ growth process parameters.

[0110] In this step, the size and shape of the microlens shell layer formed are related to the step seed related parameters and the in-situ growth process parameters. The step seed related parameters refer to parameters related to the step seed structure, such as the step difference, the size (such as the height, the lower bottom length, and the upper top length) of the top seed layer. The in-situ growth process parameters refer to parameters involved in the in-situ growth process of chemical vapor deposition, such as whether a high-temperature annealing process is used.

[0111] In an embodiment, by preparing a step seed structure with a conical top seed layer, a semi-olive ball-shaped microlens can be prepared. If necessary, the semi-olive ball-shaped microlens can continue to flow and reflow to a semi-spherical shape through subsequent high-temperature annealing. By preparing a top seed layer with a lower bottom of 2 um, an upper top of 1.6 um, and a height of 1.5 um, and then growing PSG 1 um through CVD, a semi-olive ball-shaped microlens can be obtained. After annealing at 500℃-800℃ in a nitrogen environment for 2 hours, a semi-spherical microlens can be obtained.

[0112] It can be understood that after the microlens shell layer is formed based on this scheme, the microlens shell layer can be further processed to precisely control the shape of the microlens shell layer, which is not limited in the present application.

[0113] In summary, the preparation method of the microlens provided by the embodiments of the present application can prepare a step seed structure based on a conventional step difference scheme, directly perform chemical vapor deposition on the step seed structure to form a microlens by in-situ growth, and the overall process does not need to perform complex special melting and special etching techniques, thereby reducing the process difficulty and complexity, realizing good compatibility with semiconductor processes, and ensuring low cost and yield in mass production.

[0114] Further, the microlens shell layer formed by in-situ growth is an inorganic transparent material, which is more resistant to high temperature and mechanical deformation than organic materials.

[0115] Further, in the preparation process of the microlens, the size and morphology of the microlens can be flexibly controlled through the design of the step seed structure and the in-situ growth process such as high-temperature annealing, without the need for separate preparation of a stamping template or the like, and the operation is convenient for mass production.

[0116] All the optional technical solutions described above 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.

[0117] It should be noted that the above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A microlens based on a step seed, characterized by, The microlens comprises: The step seed structure comprises a bottom flat layer and a top seed layer arranged on the bottom flat layer, and the length of the top seed layer is less than the length of the bottom flat layer, so that a step difference is formed between the top seed layer and the bottom flat layer; A microlens shell layer is arranged around the periphery of the step seed structure, the microlens shell layer is an inorganic transparent material, and the microlens shell layer is convex in the direction away from the bottom flat layer.

2. The lenticule of claim 1, wherein, The step seed structure is a pixel structure, which comprises a pixel unit and a CMOS layer at the bottom of the pixel unit; At least one top layer in the pixel structure serves as the top seed layer, and at least one bottom layer in the pixel structure serves as the bottom flat layer.

3. The microlens of claim 2, wherein The top seed layer comprises a compound pixel layer in the pixel unit, and the bottom flat layer comprises an ohmic layer, a bonding layer and the CMOS layer in the pixel unit; Or; The top seed layer comprises a compound pixel layer, an ohmic layer and a bonding layer in the pixel unit, and the bottom flat layer comprises a CMOS layer at the bottom of the pixel unit.

4. The microlens of claim 1, wherein The step seed structure is a pixel structure with a filling layer, which comprises a pixel unit, a CMOS layer at the bottom of the pixel unit, and a filling layer at the top of the pixel unit, the filling layer being made of a high-temperature-resistant organic material or an inorganic medium material; At least one top layer in the pixel structure with a filling layer serves as the top seed layer, and at least one bottom layer in the pixel structure with a filling layer serves as the bottom flat layer.

5. The microlens of claim 4, wherein The top seed layer comprises the filling layer in the pixel structure with a filling layer, and the bottom flat layer comprises the pixel unit and the CMOS layer in the pixel structure with a filling layer.

6. The microlens of claim 5, wherein The filling layer gradually decreases in size in the direction away from the CMOS layer.

7. The lenticule of claim 4, wherein, The filling layer comprises: A first filling layer above the top of the pixel unit, a second filling layer above the first filling layer, and the length of the second filling layer is less than the length of the first filling layer, the top seed layer comprises the second filling layer in the pixel structure with a filling layer, and the bottom flat layer comprises the first filling layer, the pixel unit and the CMOS layer in the pixel structure with a filling layer.

8. The microlens of claim 4, wherein The central axis of the filling layer is aligned with the central axis of the pixel unit.

9. The microlens of claim 2 or 4, wherein The pixel unit further comprises a passivation layer arranged on the sidewall.

10. The microlens of claim 9, wherein The surface of the passivation layer and the top surface of the pixel unit are further covered with a common cathode layer.

11. The microlens of claim 1, wherein The step difference is between 0.5 μm and 10 μm.

12. The microlens according to claim 1, wherein, The bottom diameter of the top seed layer is between 0.5 μm and 10 μm.

13. The microlens according to claim 1, wherein, The bottom diameter of the top seed layer is 0.4 to 0.8 times the center distance of adjacent pixel units.

14. The microlens according to claim 1, wherein, The ratio of the step difference to the bottom diameter of the top seed layer is between 0.5 and 3.

15. The microlens according to claim 1, wherein, The height of the microlens shell layer is 0.5 times to 3 times the diameter of the microlens shell layer.

16. The microlens according to claim 1, wherein, The diameter of the microlens shell layer is 0.8 to 1 times the center distance of adjacent pixel units.

17. The lenticule of claim 1, wherein, The shape of the top seed layer includes: cylindrical, prism, cone, pyramid.

18. The lenticule of claim 1, wherein, The shape of the microlens shell layer includes: semi-spherical, semi-olive ball.

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