Optical chip structure, light-emitting device and preparation method

Abstract

The invention discloses an optical chip structure, a light-emitting device and a preparation method. The optical chip structure comprises an epitaxial lamination layer and a color conversion structure, the epitaxial lamination layer comprises a semiconductor transition layer, a first semiconductor layer and a light-emitting step unit which are laminated in sequence, and the light-emitting step unit comprises a light-emitting layer, a second semiconductor layer and a refraction layer which are laminated in sequence; a first electrode is arranged on the side, away from the second semiconductor layer, of the refraction layer, a second electrode is arranged on the side, away from the semiconductor transition layer, of the first semiconductor layer, and a first light reflection layer wraps the light-emitting step unit and the current expansion layer. The color conversion structure is formed on the side, away from the first semiconductor layer, of the semiconductor transition layer. The preparation method comprises the following steps: etching the epitaxial structure into the light-emitting step unit; preparing a current expansion layer; plating a first light reflecting layer on the surface; preparing an electrode layer; and preparing the color conversion structure. The light-passing reflecting layer replaces side wall metal and a passivation layer, the complexity of structural design is reduced, the product yield is improved, and the light extraction efficiency and the production efficiency are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of LED chips, in particular to a light chip structure, a light emitting device and a preparation method. BACKGROUND

[0002] Micro-LED refers to a high-density integrated LED array, which has the advantages of low power consumption, high brightness, long service life, high contrast ratio, etc. With the gradual development of display technology, Micro-LED display technology has gradually become a trend of new display technology. Micro-LED usually adopts a color conversion scheme to realize full color, which avoids the difficulty of transferring multi-color chips and becomes a mainstream research direction. This technology can simplify the process chain, reduce manufacturing costs, and support ultra-high resolution display. In the process of realizing Micro-LED full color using color conversion materials, the crosstalk between adjacent pixels of the light emitting chip will greatly affect the light extraction efficiency and color gamut of the full-color device. Adding a side wall metal process on the side of the light emitting chip can slow down the light crosstalk phenomenon and improve the light extraction efficiency.

[0003] However, due to the side wall metal, it is easy to lap joint to the electrode structure of the device in the preparation process, causing abnormal electrical properties. Moreover, due to the complexity and tolerance of the side wall metal process, it is very easy to cause a significant decrease in yield and a decrease in production efficiency during the preparation of the light emitting chip. In the process of realizing Micro-LED colorization, high requirements are put forward for the light crosstalk of the light emitting chip. Although the side wall metal can effectively improve the light crosstalk phenomenon, the introduction of metal can easily cause electrical abnormalities.

[0004] Therefore, it is necessary to develop a light chip structure, a light emitting device and a preparation method to realize the purpose of greatly improving the light extraction efficiency and production efficiency under the premise of improving the light crosstalk effect. SUMMARY

[0005] The embodiments of the present application provide a light chip structure, a light emitting device and a preparation method, which are used to solve the problem that the existing Micro-LED adds a side wall metal process on the side of the light emitting chip, which easily causes electrical abnormalities.

[0006] The present application solves the above technical problems mainly through the following technical solutions: A light chip structure is provided, comprising: An epitaxial stack includes a semiconductor transition layer, a first semiconductor layer, and a light-emitting step unit stacked sequentially. The light-emitting step unit includes a light-emitting layer, a second semiconductor layer, and a refractive layer stacked sequentially in a direction away from the first semiconductor layer. A first electrode is provided on the side of the refractive layer away from the second semiconductor layer, and a second electrode is provided on the side of the first semiconductor layer away from the semiconductor transition layer. A first light-reflecting layer is wrapped around the outside of the light-emitting step unit. The color-changing structure is formed on the side of the semiconductor transition layer away from the first semiconductor layer.

[0007] Furthermore, the optical chip structure also includes a transparent substrate, which is formed on the side of the color conversion structure opposite to the epitaxial stack.

[0008] Furthermore, the first light-reflecting layer is a distributed Bragg reflector layer.

[0009] Furthermore, both the first electrode and the second electrode are formed in the first light-reflecting layer, and their surfaces are exposed outside the first light-reflecting layer.

[0010] Furthermore, the color conversion structure includes a stacked shielding layer and a second light reflecting layer. The shielding layer is located between the second light reflecting layer and the semiconductor transition layer. The shielding layer and the second light reflecting layer have an opening and are filled with a light-emitting material. A resonant cavity is defined between the first light reflecting layer and the second light reflecting layer, in which light is reflected multiple times.

[0011] Furthermore, the second light-reflecting layer is a distributed Bragg reflector layer.

[0012] Furthermore, the first electrode includes a stacked first current spreading layer and a first electrode layer, with the first current spreading layer disposed between the first electrode layer and the refractive layer. The second electrode includes a sequentially stacked metal pad layer, a second current spreading layer, and a second current layer, with the metal pad layer disposed between the first semiconductor layer and the second current spreading layer.

[0013] The beneficial technical effects of the optical chip structure of the present invention are as follows: By replacing the sidewall metal and passivation layer in traditional optical chips with a light-reflecting layer, compared to traditional technologies, only the light-emitting step unit needs to be wrapped with a light-reflecting layer. While maintaining excellent optical crosstalk suppression performance, the structure of the optical chip is simplified, reducing the complexity of the structural design for improving optical crosstalk in traditional optical chip structures, improving product yield, and increasing light extraction efficiency and production efficiency. In addition, replacing the light-shielding layer in the color conversion structure with a light-reflecting layer changes the method of improving crosstalk from absorption to reflection, which can increase the light extraction rate. Furthermore, a resonant cavity is formed between the two reflective layers, which is expected to achieve light amplification.

[0014] Also provided is a method for preparing an optical chip structure, comprising the following steps: etching a discrete light-emitting step unit from an epitaxial structure, the epitaxial structure comprising a semiconductor transition layer, a first semiconductor layer, a light-emitting layer, a second semiconductor layer and a refractive layer which are sequentially stacked, the light-emitting step unit extending from the refractive layer to the first semiconductor layer; preparing a current spreading layer on the surface of the refractive layer and the first semiconductor layer, respectively; coating a light-reflecting material on the surface of the epitaxial structure to form a first light-reflecting layer; opening a position corresponding to the current spreading layer on the first light-reflecting layer to expose the position of the electrode layer, preparing an electrode layer at the position of the electrode layer to obtain a first semi-finished product; flip-chip transferring the first semi-finished product to a temporary substrate, taking the semiconductor transition layer as a new process surface; preparing a color conversion structure on the process surface to obtain a second semi-finished product; packaging the second semi-finished product on a transparent substrate and peeling off the temporary substrate to expose the electrode layer to obtain an optical chip structure.

[0015] Further, the step of etching a discrete light-emitting step unit from an epitaxial structure comprises: removing contaminants on the surface of the epitaxial structure; depositing an oxide layer on the surface of the refractive layer as a hard mask; forming a pattern on the surface of the hard mask by photoetching, and then etching the hard mask to form an opening, thereby forming a hard mask with a high depth-to-width ratio; etching a discrete light-emitting step unit, and controlling the depth of the step by adjusting the etching time.

[0016] Further, the step of preparing a current spreading layer on the surface of the refractive layer and the first semiconductor layer, respectively, comprises: photoetching an opening on the surface of the refractive layer and the first semiconductor layer by photoresist; depositing a layer of conductive metal on the surface of the first semiconductor layer until the height of the layer of conductive metal is consistent with the surface of the refractive layer to form a metal raised layer; depositing a layer of conductive metal on the surface of the refractive layer and the first semiconductor layer, peeling off the metal at the position covered by the photoresist, and leaving the metal at the position without photoresist, thereby obtaining a current spreading layer.

[0017] Further, the step of opening a position corresponding to the current spreading layer on the first light-reflecting layer to expose the position of the electrode layer, preparing an electrode layer at the position of the electrode layer to obtain a first semi-finished product comprises: etching an opening on the first light-reflecting layer corresponding to the position of the current spreading layer on the refractive layer and the first semiconductor layer by photoresist to expose the position of the electrode layer. Depositing a layer of metal and stripping the metal covered by photoresist, leaving the metal in the electrode layer position, forming an electrode layer, and obtaining a first semi-finished product.

[0018] Further, the color conversion structure prepared on the process surface comprises: Plating a light reflection material on the process surface to form a second light reflection layer, etching an opening in a position of the second light reflection layer corresponding to the light emitting step unit, covering a shielding layer on the surface of the second light reflection layer, etching an opening in a position of the shielding layer corresponding to the light emitting step unit, and filling a light emitting material in the opening.

[0019] The preparation method of the optical chip structure has the beneficial technical effects that: The light reflection layer replaces the traditional sidewall metal and passivation layer in the optical chip, greatly simplifies the production process, maintains excellent optical crosstalk suppression performance, and only needs to deposit a reflection material layer, avoiding the complexity and potential risk of metal deposition and stripping process. This improvement overcomes the problem of electrical abnormalities caused by metal sidewalls, significantly improves light extraction efficiency, greatly simplifies the production process, improves product yield, and simplifies the process to a certain extent, reducing the cost of product production, significantly improving the production efficiency of the product. In addition, the process design of the reflection layer in the color conversion structure optimizes the improvement method of optical crosstalk, so that the optical fiber changes from absorption to reflection in the color conversion structure, which can significantly increase the light extraction rate. In addition, the reflection layer in the color conversion structure cooperates with the reflection layer outside the pixel, which is expected to realize light amplification and effectively improve the light extraction efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only one embodiment of the present application.

[0021] Figure 1 is a structure schematic diagram of one embodiment of the optical chip structure provided by the embodiment of the present application; Figure 2 is a structure schematic diagram of another embodiment of the optical chip structure provided by the embodiment of the present application; Figure 3 is a flow chart of the preparation method of the optical chip structure provided by the embodiment of the present application; Figure 4 is a product structure diagram after depositing a hard mask on the surface of the epitaxial structure in the preparation method of the optical chip structure provided by the embodiment of the present application; Figure 5is a product structure diagram after etching a light emitting step unit on the surface of the epitaxial structure in the preparation method of the optical chip structure provided in the embodiment of the present application; Figure 6 is a product structure diagram after depositing metal and preparing a current spreading layer on the surface of the epitaxial structure in the preparation method of the optical chip structure provided in the embodiment of the present application; Figure 7 is a product structure diagram after plating a DBR film on the surface of the epitaxial structure in the preparation method of the optical chip structure provided in the embodiment of the present application; Figure 8 is a product structure diagram after transferring the whole piece to a temporary substrate in the preparation method of the optical chip structure provided in the embodiment of the present application; Figure 9 is a product structure diagram of one embodiment after preparing a color conversion structure on a new process surface in the preparation method of the optical chip structure provided in the embodiment of the present application; Figure 10 is a product structure diagram of another embodiment after preparing a color conversion structure on a new process surface in the preparation method of the optical chip structure provided in the embodiment of the present application; Figure 11 is a structure schematic diagram of a light emitting device provided in the embodiment of the present application. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some 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 work fall within the scope of protection of the present application.

[0023] In the description of the present application, it should be understood that the orientations or positional relationships indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0024] In the description of the present application, it is necessary to explain that, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection or can communicate with each other; it can be directly connected, or indirectly connected through intermediate medium, or the internal communication of two elements or the interaction relationship 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.

[0025] In the present application, unless otherwise explicitly specified and limited, the first feature "on" or "under" the second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the first feature "on", "above" and "above" the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "under", "below" and "below" the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0026] The following disclosure provides many different embodiments or examples for implementing different structures of the present application. In order to simplify the disclosure of the present application, the components and arrangements of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeatedly refer to numbers and / or letters in different examples. Such repetition is for the purpose of simplification and clarity, and in itself does not indicate the relationship between the various embodiments and / or arrangements discussed. In addition, the present application provides examples of various specific processes and materials, but those skilled in the art can realize the application of other processes and / or the use of other materials.

[0027] Specifically, the embodiment of the present application provides a light chip structure, and the finally formed light chip structure is bonded with a driving chip through an electrode to complete a light emitting device of a light chip applicable to full-color Micro LED (see Figure 11 ). The main core design of the whole light chip structure is as follows: The main structure adopts a similar design to the traditional light chip structure, the difference is that the traditional sidewall metal and passivation layer structure is replaced by a reflection layer (distributed Bragg reflector DBR) inside the chip structure. While maintaining excellent optical crosstalk suppression performance, only DBR film layer needs to be deposited to achieve it, avoiding the complexity and potential risk of metal deposition and stripping process. This improvement not only significantly improves the light extraction efficiency, but also greatly simplifies the production process, improves yield.

[0028] It needs to be particularly pointed out that the distributed Bragg reflector (DBR) is mainly used to provide high reflectivity in the optical chip to enhance the feedback of light and limit the loss of light. The distributed Bragg reflector (DBR) is formed by interlacing growth of multiple semiconductor or dielectric materials in the form of ABABAB… to obtain high reflectivity to a specific optical band.

[0029] Referring to Figure 1 and Figure 2 , the optical chip structure of the embodiment mainly includes an epitaxial stack 2 and a color conversion structure 3. The epitaxial stack 2 is formed on the surface of the color conversion structure 3. The epitaxial stack 2 specifically includes a semiconductor transition layer 21, a first semiconductor layer 22, and a light-emitting step unit which are sequentially stacked. The light-emitting step unit includes a light-emitting layer 23, a second semiconductor layer 24, and a refractive layer 25 which are sequentially stacked in a direction away from the first semiconductor layer. A first electrode is provided on the side of the refractive layer 25 away from the second semiconductor layer 24, a second electrode is provided on the side of the first semiconductor layer 22 away from the semiconductor transition layer 21, and the outside of the light-emitting step unit is wrapped with a first light reflection layer 27.

[0030] In the embodiment, the light reflection structure is provided outside the light-emitting step unit (i.e. the pixel), replacing the metal and passivation layer in the periphery of the traditional chip pixel. The light reflection structure can meet the requirement of better improvement of light crosstalk effect. Compared with the traditional technology which needs complicated processes of deposition and stripping, the light reflection structure only needs to be plated with a light reflection layer to achieve the improvement of light crosstalk, which simplifies the process to a certain extent, improves the yield, reduces the production cost, and significantly improves the light extraction efficiency and production efficiency.

[0031] In the epitaxial stack 2 of the embodiment, the semiconductor transition layer 21 is a U-GaN (un-doped gallium nitride layer), but is not limited thereto. The first semiconductor layer 22 is an N-type semiconductor layer, specifically an N-type gallium nitride layer formed by doping on the U-GaN, but is not limited thereto. The second semiconductor layer 24 is a P-type semiconductor layer, specifically a P-type gallium nitride layer, but is not limited thereto. The light-emitting layer 23 is a quantum well, but is not limited thereto. The refractive layer 25 is a superlattice structure composed of a nanometer-thick semiconductor layer, but is not limited thereto. The first light reflection layer 27 preferably adopts a distributed Bragg reflector (DBR), but is not limited thereto.

[0032] In some embodiments, a transparent substrate 1 is further included, wherein the color conversion structure 3 is formed on one side of the transparent substrate 1.

[0033] In some embodiments, a driving chip is further included, which is bonded on the side of the epitaxial stack 2 away from the color conversion structure 3, and the electrodes of the driving chip are bonded with the first electrode and the second electrode to form a light chip device of the color Micro LED.

[0034] In the embodiment, a plurality of light emitting step units are provided, and each light emitting step unit is wrapped with the first light reflection layer 27, and the first light reflection layer 27 is arranged between adjacent light emitting step units.

[0035] In one embodiment, referring to Figure 1 , the color conversion structure 3 only includes a shielding layer, and an opening penetrating to the surface of the semiconductor transition layer 21 is formed in the shielding layer, and the light emitting material 31 is filled in the opening.

[0036] The material of the shielding layer can include, but is not limited to, black glue and other high extinction materials. Due to the excellent light shielding characteristics and good process adaptability, such materials can effectively block light penetration and ensure that the light shielding effect meets the design requirements. In addition, according to different product requirements and use environments, other composite materials or coating technologies with similar optical properties can also be considered to meet more stringent light shielding performance indicators. The shielding layer can be coated with a light shielding material on one side surface of the semiconductor transition layer 21 by spin coating, spraying or deposition process, thereby forming a light shielding material layer.

[0037] In other examples, the material of the shielding layer can include, but is not limited to, silver or aluminum and other high reflectivity metals, for example, the shielding layer can be a silver foil layer or an aluminum foil layer. It can be understood that compared with the light shielding layer formed by photoresist, the silver foil layer or the aluminum foil layer has the problem of high light absorption and serious light energy damage.

[0038] Referring to Figure 3 , the specific preparation method of the light chip structure in the above embodiment includes the following steps: S10, etching the epitaxial structure into a discrete light emitting step unit; Referring to Figure 4 , the epitaxial structure can be an epitaxial structure with a sapphire substrate a, and the substrate a adopts a sapphire sheet. The epitaxial structure on the substrate a includes a semiconductor transition layer, a first semiconductor layer, a light emitting layer, a second semiconductor layer and a refractive layer which are sequentially stacked, and the light emitting step unit extends from the refractive layer to the first semiconductor layer.

[0039] In the embodiment, there is also a buffer layer between the substrate a and the semiconductor transition layer.

[0040] Specifically, the light emitting step unit is formed by the following method: S101, the surface of the epitaxial structure is cleaned to remove contaminants.

[0041] The cleaning technique can be plasma cleaning or other conventional cleaning method.

[0042] S102、Refer to Figure 4 An oxide layer is deposited on the surface of the refractive layer of the epitaxial structure as a hard mask. The oxide can be SiO2 or other oxide that has higher etching resistance. S103, a photoresist is patterned on the surface of the hard mask by photolithography, and then the hard mask is etched to form an opening, thereby forming a hard mask with high depth-width ratio. S104、Refer to Figure 5 The epitaxial structure is further etched by ICP or IBE to form discrete light-emitting step units. During the etching process, the depth of the step is controlled by adjusting the etching time.

[0043] S20、Refer to Figure 6 A current spreading layer is prepared on the surface of the refractive layer and the first semiconductor layer. The specific method is as follows: S201, a photoresist is patterned on the surface of the refractive layer and the first semiconductor layer; S202, a layer of conductive metal is deposited on the surface of the first semiconductor layer until its height is consistent with the surface of the refractive layer, thereby forming a metal elevation layer; S203, a layer of conductive metal is deposited on the surface of the refractive layer and the first semiconductor layer, the metal covered by the photoresist is stripped, and the metal without the photoresist is retained, thereby obtaining the current spreading layer (h and g in the figure refer to). The first current spreading layer is formed on the surface of the refractive layer, and the second current spreading layer is formed on the surface of the first semiconductor layer.

[0044] In this embodiment, the material of the current spreading layer can include at least one of titanium (Ti), gold (Au), platinum (Pt), nickel (Ni), and aluminum (Al).

[0045] It should be noted that in this embodiment, since there is a height difference between the refractive layer and the first semiconductor layer, the photoresist is first patterned on the surface of the refractive layer and the first semiconductor layer, then the conductive metal is deposited on the opening of the first semiconductor layer until its height is consistent with the surface of the refractive layer to form a metal elevation layer, and then the current spreading layer is deposited on the surface of the refractive layer and the first semiconductor layer. After the final molding, the surface height of the current spreading layer on the surface of the refractive layer and the first semiconductor layer is consistent or similar.

[0046] S30、Refer to Figure 7After the current spreading layer is made, a distributed Bragg reflector (DBR, first light reflection layer) with a specific film layer structure is plated on the surface of the epitaxial structure by atomic layer deposition (ALD) or evaporation, etc., to achieve the effect of reflecting a specific wavelength of light. Then, an opening is etched on the part of the current spreading layer on the corresponding refractive layer and the first semiconductor layer of the first light reflection layer by photoresist, to expose the position for preparing the electrode layer. Next, a layer of metal is deposited on the surface of the epitaxial structure, and the metal covered by the photoresist is stripped, and the metal in the position of the electrode layer is retained, so that the electrode layer is formed in the position of the electrode layer, and a first semi-finished product is obtained, wherein the metal spreading layer and the electrode layer jointly form an electrode, and the first electrode P (also referred to as P electrode) is formed on the surface of the refractive layer, and the second electrode N (also referred to as N electrode) is formed on the surface of the first semiconductor layer.

[0047] S40, refer to Figure 8 The first semi-finished product is transferred to a temporary substrate c in an inverted manner, and the substrate a is stripped by a laser stripping technology, and the buffer layer between the substrate and the semiconductor transition layer is also stripped, so that the semiconductor transition layer is exposed as a new process surface. It should be noted that the epitaxial structure in this embodiment can also be a homoepitaxy without a substrate. If it is such an epitaxy, the operation of stripping the substrate and the buffer layer is not needed after being transferred to the temporary substrate, and the next process is directly performed.

[0048] S50, refer to Figure 9 The color conversion structure is prepared on the process surface, and the specific method is as follows: A layer of black photoresist (i.e., a shielding layer) is deposited on the process surface by a photolithography technology, and openings (collectively referred to as banks) are photolithographically formed on the black photoresist layer at positions corresponding to the light emitting step units, so that the light emitting material can be filled into the openings. Then, the light emitting material is filled into the openings, and discrete light emitting units are formed, which correspond to the light emitting step units one by one, to obtain a second semi-finished product.

[0049] S60, refer to Figure 1 After the color conversion structure is completed, the second semi-finished product is mounted on a transparent substrate, and the temporary substrate is stripped to expose the first electrode and the second electrode for bonding with the driving chip, and the structure of the light chip applicable to full-color Micro LED is completed.

[0050] The transparent substrate 1 includes but is not limited to a glass substrate.

[0051] In this embodiment, the first electrode is formed on the surface of the light emitting step unit, and the second electrode layer is formed on the periphery of the light emitting step unit and between adjacent light emitting step units. The materials of the first electrode layer and the second electrode layer can each include at least one of titanium (Ti), gold (Au), platinum (Pt), nickel (Ni), and aluminum (Al) and the like.

[0052] In the embodiment, at least one light-emitting step unit is provided, and the corresponding light-emitting material 31 is arranged on the side of the semiconductor transition layer 21 away from the light-emitting step unit.

[0053] In another embodiment, referring to Figure 2 , the color conversion structure 3 includes a distributed stack of a shielding layer and a second light reflection layer 32, and the shielding layer is arranged between the second light reflection layer 32 and the semiconductor transition layer 21. The shielding layer and the second light reflection layer 32 are both provided with an opening, and the light-emitting material 31 is filled in the opening. Among them, the second light reflection layer 32 preferably adopts a distributed Bragg reflector (DBR), but is not limited thereto.

[0054] Among them, the material of the shielding layer can include, but is not limited to, high extinction materials such as black glue. Due to its excellent light shielding characteristics and good process adaptability, such materials can effectively block light penetration and ensure that the light shielding effect meets the design requirements. In addition, according to different product requirements and use environments, other composite materials or coating technologies with similar optical properties can also be considered to meet more stringent light shielding performance indicators. The shielding layer can be coated with a light shielding material on the surface of the semiconductor transition layer 21 side through processes such as spin coating, spraying or deposition, thereby forming a light shielding material layer.

[0055] In other examples, the material of the shielding layer includes, but is not limited to, high-reflectivity metals such as silver or aluminum. For example, the shielding layer can be a silver foil layer or an aluminum foil layer. It can be understood that compared with the light shielding layer formed by photoresist, the silver foil layer or the aluminum foil layer has the problem of high light absorption and serious light energy damage.

[0056] The specific preparation method of the optical chip structure in the above embodiment includes the following steps: S10, etching the epitaxial structure into a discrete light-emitting step unit; Among them, referring to Figure 4 , the epitaxial structure can be an epitaxial structure with a sapphire substrate a, the substrate a adopts a sapphire sheet, and the epitaxial structure on the substrate a includes a semiconductor transition layer, a first semiconductor layer, a light-emitting layer, a second semiconductor layer and a refractive layer which are sequentially stacked, and the light-emitting step unit extends from the refractive layer to the first semiconductor layer.

[0057] In the embodiment, there is also a buffer layer between the substrate a and the semiconductor transition layer.

[0058] Specifically, the light-emitting step unit is formed by the following method: S101, pre-clean to remove surface contaminants of the epitaxial structure.

[0059] Among them, the cleaning technology can adopt plasma cleaning or other conventional cleaning means.

[0060] S102、Refer to Figure 4 An oxide layer is deposited on the surface of the refractive layer of the epitaxial structure as a hard mask. The oxide layer can be SiO2 or other oxides, which have higher etching resistance. S103、A photoresist is patterned on the surface of the hard mask by photolithography, and then the hard mask is etched to form an opening, thereby forming a hard mask with high depth-width ratio. S104、Refer to Figure 5 The epitaxial structure is further etched by ICP or IBE to form discrete light-emitting step units. During the etching process, the depth of the steps is controlled by adjusting the etching time.

[0061] S20、Refer to Figure 6 A current spreading layer is prepared on the surface of the refractive layer and the first semiconductor layer. The specific method is as follows: S201、A photoresist is patterned on the surface of the refractive layer and the first semiconductor layer. S202、A layer of conductive metal is deposited on the surface of the first semiconductor layer until its height is consistent with that of the surface of the refractive layer, thereby forming a metal pad layer. S203、A layer of conductive metal is deposited on the surface of the refractive layer and the first semiconductor layer. The metal on the position covered by the photoresist is stripped, while the metal on the position without the photoresist is retained, thereby obtaining the current spreading layer. The first current spreading layer is formed on the surface of the refractive layer, and the second current spreading layer is formed on the surface of the first semiconductor layer.

[0062] In this embodiment, the material of the current spreading layer 26 can be at least one of titanium (Ti), gold (Au), platinum (Pt), nickel (Ni), and aluminum (Al).

[0063] It should be noted that, in this embodiment, since there is a height difference between the refractive layer 25 and the first semiconductor layer 22, the photoresist is first patterned on the surface of the refractive layer and the first semiconductor layer, and then a conductive metal is deposited on the opening of the first semiconductor layer until its height is consistent with that of the surface of the refractive layer, thereby forming a metal pad layer. After that, the current spreading layer is deposited on the surface of the refractive layer and the first semiconductor layer. Finally, the surface height of the current spreading layer 26 on the surface of the refractive layer 25 and the first semiconductor layer 22 is consistent or similar.

[0064] S30、Refer to Figure 7After the current spreading layer is formed, a distributed Bragg reflector (DBR) (first light reflection layer 27) is formed on the surface of the epitaxial structure by atomic layer deposition (ALD) or evaporation, so as to reflect light of a specific wavelength; then, the current spreading layer on the first light reflection layer corresponding to the refractive layer and the first semiconductor layer is etched by photoresist to form an opening, so as to expose a position for forming an electrode layer; next, a layer of metal is deposited on the surface of the epitaxial structure, and the metal covered by the photoresist is removed, so that the metal in the position of the electrode layer is retained, thereby forming an electrode layer in the position of the electrode layer, and a first semi-finished product is obtained, wherein the metal spreading layer and the electrode layer jointly form an electrode, the first electrode (P electrode) is formed on the surface of the refractive layer, and the second electrode (N electrode) is formed on the surface of the first semiconductor layer.

[0065] S40, refer to Figure 8 The first semi-finished product is transferred to a temporary substrate c by flip-chip, and the substrate a is removed by laser stripping, and the buffer layer between the substrate and the semiconductor transition layer is also removed, so that the semiconductor transition layer is exposed as a new process surface; S50, refer to Figure 10 A color conversion structure is prepared on the process surface, and the specific method is as follows: First, a distributed Bragg reflector (DBR) (i.e., a second light reflection layer) is formed on the surface of the process surface by atomic layer deposition (ALD) or evaporation, so that the DBR can reflect the light emitted by the light chip, and then an opening is formed on the second light reflection layer corresponding to the light emitting step unit by photoetching / etching technology, so that the light can be emitted. Then, a black glue layer (i.e., a shielding layer) is formed on the surface of the second light reflection layer, and an opening (referred to as a bank) is formed on the black glue layer corresponding to the light emitting step unit, so that the light emitting material can be filled. Finally, the light emitting material is filled into the opening to form discrete light emitting units corresponding to the light emitting step units one by one, and a second semi-finished product is obtained.

[0066] S60, refer to Figure 2 After the color conversion structure is completed, the second semi-finished product is packaged on a transparent substrate, the temporary substrate is removed, the first electrode and the second electrode bonded with the driving chip are exposed, and the structure of the light chip applicable to full-color Micro LED is completed.

[0067] In some embodiments, refer to Figure 11 After the light chip structure obtained in step S60 is removed from the substrate, the first electrode and the second electrode are bonded with the corresponding electrodes of the driving chip D to form a light emitting device.

[0068] The advantages of the light chip structure obtained by the present embodiment compared with the color conversion structure 3-layer single shielding layer are as follows: The color conversion structure 3 is designed as a double-layer structure, and a second light reflection layer 32 is added between the original shielding layer and the light emitting surface, so that the crosstalk mode is changed from absorption to reflection, and the light output rate can be further increased.

[0069] In addition, the second light reflection layer 32 in the color conversion structure 3 can define a resonant cavity with the first light reflection layer 27 at the light chip, and the light amplification effect can be achieved by using the resonant cavity.

[0070] In the above embodiments, the description of each embodiment has its own focus, and the parts not described in detail in a certain embodiment can be referred to the related description of other embodiments.

[0071] The above describes in detail the light chip structure, the light emitting device and the preparation method provided by the embodiments of the present application. The specific examples are applied to describe the principles and implementation manners of the present application. The above description of the embodiments is only used to help understand the technical solutions and the core idea of the present application; the ordinary skilled in the art should understand that the technical solutions recorded in the above embodiments can be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An optical chip structure, characterized by The light chip structure comprises: an epitaxial stack comprising a semiconductor transition layer, a first semiconductor layer and a light-emitting step unit which are sequentially stacked, the light-emitting step unit comprising a light-emitting layer, a second semiconductor layer and a refractive layer which are sequentially stacked in a direction away from the first semiconductor layer; a first electrode is arranged on a side of the refractive layer away from the second semiconductor layer, a second electrode is arranged on a side of the first semiconductor layer away from the semiconductor transition layer, and an outer portion of the light-emitting step unit is wrapped with a first light-reflecting layer; a color conversion structure formed on a side of the semiconductor transition layer away from the first semiconductor layer.

2. The optical chip structure of claim 1, wherein: The light chip structure further comprises a transparent substrate formed on a side of the color conversion structure away from the epitaxial stack.

3. The optical chip structure of claim 1, wherein: The first light-reflecting layer is a distributed Bragg reflector layer.

4. The optical chip structure of claim 1, wherein: The first electrode and the second electrode are both formed in the first light-reflecting layer, and surfaces of both are exposed to the first light-reflecting layer.

5. The optical chip structure of claim 1, wherein: The color conversion structure comprises a shielding layer and a second light-reflecting layer which are stacked, the shielding layer is arranged between the second light-reflecting layer and the semiconductor transition layer, an opening is arranged in the shielding layer and the second light-reflecting layer, and a light-emitting material is filled in the opening, and a resonant cavity for multiple reflections of light between the first light-reflecting layer and the second light-reflecting layer is defined.

6. An optical chip structure according to any one of claims 1 to 5, characterized in that: The second light-reflecting layer is a distributed Bragg reflector layer.

7. An optical chip structure according to any one of claims 1 to 5, characterized in that: The first electrode comprises a first current spreading layer and a first electrode layer which are stacked, the first current spreading layer is arranged between the first electrode layer and the refractive layer, and the second electrode comprises a metal pad layer, a second current spreading layer and a second electrode layer which are sequentially stacked, the metal pad layer is arranged between the first semiconductor layer and the second current spreading layer.

8. A light-emitting device, characterized in that: The light chip structure comprises any one of claims 1 to 7.

9. A method of fabricating an optical chip structure, characterized by, The method comprises the following steps: etching an epitaxial structure to form discrete light-emitting step units, the epitaxial structure comprising a semiconductor transition layer, a first semiconductor layer, a light-emitting layer, a second semiconductor layer and a refractive layer which are sequentially stacked, the light-emitting step units extending from the refractive layer to the first semiconductor layer; preparing a current spreading layer on surfaces of the refractive layer and the first semiconductor layer, respectively; coating a light-reflecting material on a surface of the epitaxial structure to form a first light-reflecting layer; opening the first light-reflecting layer at positions of the current spreading layer to expose positions of electrode layers, and preparing the electrode layers at the positions of the electrode layers to obtain a first-level semi-finished product; flip-chip transferring the first-level semi-finished product to a temporary substrate, taking the semiconductor transition layer as a new process surface; preparing a color conversion structure on the process surface to obtain a second-level semi-finished product; packaging the second-level semi-finished product on a transparent substrate, and peeling off the temporary substrate to expose the electrode layers, thereby obtaining a light chip structure.

10. The method of claim 9, wherein the method further comprises: The etching of the epitaxial structure to form discrete light-emitting step units comprises: removing contaminants on a surface of the epitaxial structure; depositing an oxide layer on a surface of the refractive layer as a hard mask; etching the discrete light-emitting step units, and controlling the depth of the step units by adjusting etching time.

11. The method of claim 9, wherein the method further comprises: The preparation of the current spreading layer on surfaces of the refractive layer and the first semiconductor layer, respectively, comprises: photolithographing a photoresist on surfaces of the refractive layer and the first semiconductor layer to form openings; Depositing a layer of conductive metal on the surface of the first semiconductor layer until its height is consistent with the surface of the refractive layer, forming a metal raised layer; Depositing a layer of conductive metal on the surface of the refractive layer and the first semiconductor layer, stripping the metal at the positions covered by photoresist, and leaving the metal at the positions without photoresist, thereby obtaining a current spreading layer.

12. The method of claim 9, wherein the method further comprises: Said opening at the position of the current spreading layer on the first light reflecting layer exposes the position of the electrode layer, and the electrode layer is prepared at the position of the electrode layer, thereby obtaining a first semi-finished product including: Etching an opening at the position of the current spreading layer on the first light reflecting layer corresponding to the refractive layer and the first semiconductor layer by photoresist, thereby exposing the position of the electrode layer; Depositing a layer of metal, stripping the metal at the positions covered by photoresist, and leaving the metal at the position of the electrode layer, thereby forming the electrode layer and obtaining a first semi-finished product.

13. A method of fabricating an optical chip structure according to any one of claims 9 to 12, wherein, Said preparation of a color conversion structure on the process surface includes: Plating a light reflecting material on the process surface to form a second light reflecting layer, etching an opening at the position of the second light reflecting layer corresponding to the light emitting step unit, covering the second light reflecting layer with a shielding layer, etching an opening at the position of the shielding layer corresponding to the light emitting step unit, and filling the opening with a light emitting material.

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