Micro-led chip and preparation method thereof

Abstract

The application provides a Micro-LED chip and a preparation method thereof. An insulating layer is grown on a substrate and subjected to photolithography to form a plurality of grooves and columnar structures with a certain inclination. An epitaxial layer is grown on the columnar structures and the grooves, so that the side surface of the epitaxial layer is chamfered. The columnar structures are polished until the surface of the columnar structures is flush with the epitaxial layer in the grooves. The remaining columnar structures are removed to obtain an epitaxial layer with isolation grooves. The chip preparation is completed based on the epitaxial layer with the isolation grooves. The inclination of the columnar structures is formed and utilized to chamfer the side surface of the epitaxial layer, so that dry etching of the epitaxial layer is not needed, damage to the side wall of the epitaxial layer is avoided, and the light-emitting efficiency of the Micro-LED chip prepared based on the epitaxial layer with the isolation grooves is improved. Meanwhile, the side surface of the epitaxial layer is chamfered, and the light-emitting brightness of the side wall of the Micro-LED chip is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor light-emitting device technology, and in particular to a Micro-LED chip and its fabrication method. Background Technology

[0002] Micro-LED array-based microdisplays have great application prospects. Compared with traditional liquid crystal displays (LCDs) and organic light-emitting diode displays (OLEDs), they have advantages such as high efficiency, low power consumption, ultra-high resolution, ultra-fast response speed and wide viewing angle. They are considered a "next-generation display technology". However, the fabrication of Micro-LED chips is difficult, especially the fabrication of the isolation trenches of Micro-LED chips.

[0003] Specifically, currently, dry etching is generally used when fabricating isolation trenches for Micro-LED chips. However, the plasma generated during the dry etching process inevitably introduces sidewall etching damage at the device edge and generates sidewall dangling bonds, which leads to a decrease in the luminous efficiency of the Micro-LED chip. Summary of the Invention

[0004] In view of this, embodiments of the present invention provide a Micro-LED chip and a method for fabricating the same, in order to improve the luminous efficiency of the Micro-LED chip.

[0005] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0006] The first aspect of this invention discloses a method for fabricating a Micro-LED chip, the method comprising:

[0007] Provide a substrate;

[0008] An insulating layer is grown on the substrate;

[0009] The insulating layer is photolithographically etched to form multiple trenches and columnar structures with a certain angle;

[0010] An epitaxial layer is grown on the columnar structure and the trench, and the sides of the epitaxial layer are chamfered.

[0011] Grind and polish the columnar structure until the surface of the columnar structure is flush with the epitaxial layer in the trench;

[0012] Remove the remaining columnar structure to obtain an epitaxial layer with isolation grooves;

[0013] The chip is fabricated based on the epitaxial layer with isolation trenches.

[0014] Optionally, growing an insulating layer on the substrate includes:

[0015] An insulating layer of SiO2 and / or SiN is grown on the substrate.

[0016] Optionally, photolithography of the insulating layer to form multiple trenches and columnar structures with a certain angle includes:

[0017] The insulating layer is coated with adhesive, exposed, and developed to form a photolithographic pattern.

[0018] Photolithography is performed based on the photolithographic pattern of the insulating layer to form multiple trenches and an initial columnar structure with a first tilt angle;

[0019] The initial columnar structure is etched to form a columnar structure with a second tilt angle, wherein the range of the second tilt angle is a subset of the range of the first tilt angle.

[0020] Optionally, the first tilt angle ranges from 0 degrees to 80 degrees;

[0021] The second tilt angle ranges from 30 degrees to 80 degrees.

[0022] Optionally, photolithography is performed based on the photolithographic pattern of the insulating layer to form multiple trenches and an initial columnar structure with a first tilt angle, including:

[0023] Photolithography is performed based on the photolithographic pattern of the insulating layer to form multiple trenches and an initial columnar structure with a first tilt angle of 30 degrees;

[0024] Accordingly, etching the initial columnar structure to form a columnar structure with a second tilt angle includes:

[0025] The initial columnar structure is etched to form a second columnar structure with an inclination angle of 50 degrees.

[0026] Optionally, growing an epitaxial layer on the columnar structure and the trench, and forming a chamfer on the side surface of the epitaxial layer includes:

[0027] An epitaxial layer is grown on the columnar structure and the trench, such that the side surface of the epitaxial layer is chamfered relative to a second tilt angle.

[0028] Optionally, growing an epitaxial layer on the columnar structure and the trench, and forming a chamfer on the side surface of the epitaxial layer includes:

[0029] An epitaxial layer is grown on the columnar structure and the trench, such that the side surface of the epitaxial layer has a chamfer with an inclination angle ranging from 10 degrees to 60 degrees.

[0030] Optionally, removing the remaining columnar structure to obtain an epitaxial layer with isolation grooves includes:

[0031] The remaining columnar structure was removed using BOE solution to obtain an epitaxial layer with isolation grooves.

[0032] Optionally, the width of the isolation groove is smaller than the width of the trench.

[0033] The second aspect of the present invention discloses a Micro-LED chip, which is prepared by the Micro-LED chip preparation method disclosed in the first aspect of the present invention.

[0034] Based on the Micro-LED chip and its fabrication method provided in the above embodiments of the present invention, the method includes: providing a substrate; growing an insulating layer on the substrate; photolithographically etching the insulating layer to form multiple trenches and columnar structures with a certain tilt angle; growing an epitaxial layer on the columnar structures and trenches, such that the sides of the epitaxial layer are chamfered; grinding and polishing the columnar structures until the surface of the columnar structures is flush with the epitaxial layer in the trenches; removing the remaining columnar structures to obtain an epitaxial layer with isolation trenches; and completing chip fabrication based on the epitaxial layer with isolation trenches. In the embodiments of the present invention, by forming and utilizing the tilt angle of the columnar structures to chamfer the sides of the epitaxial layer, dry etching of the epitaxial layer is unnecessary, avoiding damage to the sidewalls of the epitaxial layer, thereby improving the luminous efficiency of the Micro-LED chip fabricated based on the epitaxial layer with isolation trenches; at the same time, the chamfered sides of the epitaxial layer effectively improve the light emission brightness of the sidewalls of the Micro-LED chip. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0036] Figure 1 A flowchart illustrating a method for fabricating a Micro-LED chip according to an embodiment of the present invention;

[0037] Figure 2 This is a cross-sectional view of an insulating layer grown on a substrate according to an embodiment of the present invention;

[0038] Figure 3 A cross-sectional view of a columnar structure with multiple grooves and a certain angle, provided in an embodiment of the present invention;

[0039] Figure 4 This is a cross-sectional view of an epitaxial layer after growth, provided in an embodiment of the present invention.

[0040] Figure 5 This is a cross-sectional view of a columnar structure after grinding and polishing, provided in an embodiment of the present invention;

[0041] Figure 6 This is a cross-sectional view of an epitaxial layer with isolation grooves provided in an embodiment of the present invention. Detailed Implementation

[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] In this application, the terms "comprising," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0044] The fabrication of micro-LED chips with fine pitch is extremely difficult. On the one hand, it is limited by high-resolution equipment and photoresist, making fine-pitch photolithography very challenging. On the other hand, the etching process of the isolation trench introduces sidewall damage and dangling bonds, which leads to a decrease in the luminous efficiency of the micro-LED chip.

[0045] Therefore, in order to solve the two problems existing in the Micro-LED chip mentioned above, this invention provides a method for preparing a Micro-LED chip.

[0046] like Figure 1 The diagram shows a flowchart of a method for fabricating a Micro-LED chip according to an embodiment of the present invention. The method includes:

[0047] S11: Provide a substrate.

[0048] In S11, the substrate can be a sapphire substrate, a silicon substrate, or a silicon carbide substrate.

[0049] S12: Growing an insulating layer on the substrate.

[0050] In S12, the insulating layer is made of insulating material. Specifically, the insulating layer can be made of high-temperature resistant insulating materials such as SiO2 and / or SiN.

[0051] That is, the insulating layer can be a SiO2 and / or SiN insulating layer.

[0052] Specifically, the insulating layer can be a single-layer structure. For example, the insulating layer can be a single-layer SiO2 layer or a SiN layer.

[0053] The insulating layer can also be a multi-layered composite structure. For example, the insulating layer is composed of a SiO2 layer and a SiN layer.

[0054] In the specific execution of S12, an insulating layer with a single-layer or multi-layer composite structure formed of high-temperature resistant insulating material can be grown on the substrate.

[0055] like Figure 2 The image shown is a cross-sectional view of an insulating layer grown on a substrate according to an embodiment of the present invention.

[0056] Depend on Figure 2 It can be seen that high-temperature resistant insulating material is deposited on substrate 1 to form an insulating layer 2 with a certain thickness, either a single-layer structure or a multi-layer composite structure.

[0057] S13: Photolithographic insulating layer, forming multiple trenches and columnar structures with a certain angle.

[0058] In the specific execution of S13, the photolithographic insulating layer is used to construct a columnar structure, and the columnar structure is adjusted to ultimately form... Figure 3 The diagram shows multiple grooves and columnar structures with a certain angle of inclination.

[0059] like Figure 3 The image shown is a cross-sectional view of a columnar structure with multiple grooves and a certain angle, provided by an embodiment of the present invention.

[0060] Depend on Figure 3 It can be seen that a columnar structure 3 with a certain tilt angle is formed on the substrate 1. The columnar structure 3 with a certain tilt angle is composed of multiple columns, wherein a groove is formed between two adjacent columns.

[0061] It should be noted that the number of columns and their positions within the columnar structure 3 with a certain angle can be adjusted according to actual needs. Similarly, the number and position of the trenches can also be adjusted as needed.

[0062] Furthermore, the depth of the trench varies depending on the height of the columnar structure 3. Therefore, in practical applications, trenches of different depths can be obtained by adjusting the height of the columnar structure 3.

[0063] In one embodiment of the present invention, the specific process of forming multiple trenches and columnar structures with a certain tilt angle includes: firstly, coating, exposing and developing the surface of the insulating layer to form a photolithographic pattern of the insulating layer; then, performing photolithography based on the photolithographic pattern of the insulating layer to form multiple trenches and an initial columnar structure with a first tilt angle; and finally, etching the initial columnar structure with the first tilt angle to form a columnar structure with a second tilt angle.

[0064] The range of values ​​for the second tilt angle is a subset of the range of values ​​for the first tilt angle.

[0065] In one embodiment of the present invention, the first tilt angle ranges from 0 degrees to 80 degrees, and the second tilt angle ranges from 30 degrees to 80 degrees. When the second tilt angle ranges from 30 to 80 degrees, it is beneficial to the stability of the columnar structure during the subsequent epitaxial layer growth process.

[0066] As can be seen from the above, by performing photolithography on the insulating layer based on the photolithographic pattern of the insulating layer and adjusting the photolithographic morphology, an initial columnar structure with a specific first tilt angle can be formed.

[0067] For example: forming an initial columnar structure with a first tilt angle of 10 degrees; forming an initial columnar structure with a first tilt angle of 30 degrees; forming an initial columnar structure with a first tilt angle of 50 degrees; forming an initial columnar structure with a first tilt angle of 70 degrees, etc.

[0068] After forming an initial columnar structure with a specific first tilt angle, an etching process, such as dry etching, is used to form a columnar structure with a specific second tilt angle.

[0069] For example: by etching an initial columnar structure with a first tilt angle of 10 degrees, a columnar structure with a second tilt angle of 30 degrees is formed; by etching an initial columnar structure with a first tilt angle of 30 degrees, a columnar structure with a second tilt angle of 50 degrees is formed; by etching an initial columnar structure with a first tilt angle of 50 degrees, a columnar structure with a second tilt angle of 60 degrees is formed; by etching an initial columnar structure with a first tilt angle of 70 degrees, a columnar structure with a second tilt angle of 80 degrees is formed.

[0070] S14: An epitaxial layer is grown on columnar structures and trenches, so that the sides of the epitaxial layer are chamfered.

[0071] In S14, the epitaxial layer may include an N-type GaN layer, a light-emitting layer, and a P-type GaN layer from bottom to top.

[0072] In the specific execution of S14, an epitaxial layer including an N-type GaN layer, a light-emitting layer, and a P-type GaN layer can be grown on the columnar structure and trench, so that the sides of the epitaxial layer including the N-type GaN layer, the light-emitting layer, and the P-type GaN layer are chamfered.

[0073] like Figure 4 The image shown is a cross-sectional view of an epitaxial layer after growth, according to an embodiment of the present invention.

[0074] Depend on Figure 4 It can be seen that the epitaxial layer 4 is grown on the columnar structure 3 with a certain tilt angle and on each trench. Since the columnar structure 3 has a certain tilt angle, the side surface of the epitaxial layer 4 grown on the columnar structure 3 and each trench has a chamfer. In other words, the chamfer formed on the side surface of the epitaxial layer is achieved by the tilt angle of the columnar structure 3.

[0075] In one embodiment of the invention, the side surface of the epitaxial layer is chamfered relative to a second tilt angle. That is, the chamfer formed on the side surface of the epitaxial layer is achieved by the second tilt angle.

[0076] Specifically, the sides of the epitaxial layer can be chamfered with an angle ranging from 10 to 60 degrees.

[0077] S15: Grind and polish the columnar structure until the surface of the columnar structure is flush with the epitaxial layer in the trench.

[0078] In the specific execution of S15, the epitaxial layer on the columnar structure is completely ground off, and the columnar structure of a certain height in the vertical direction is removed by grinding and polishing, so that the surface of the columnar structure after grinding and polishing is flush with the epitaxial layer in the trench.

[0079] The statement that the surface of the columnar structure after grinding and polishing is flush with the epitaxial layer in the trench means that there is no significant height difference between the two surfaces, but reasonable manufacturing errors in the field are allowed.

[0080] like Figure 5 The image shown is a cross-sectional view of a columnar structure after grinding and polishing, according to an embodiment of the present invention.

[0081] Depend on Figure 5 It can be seen that the surface of the columnar structure 3 after grinding and polishing is flush with the surface of the epitaxial layer 4.

[0082] S16: Remove the remaining columnar structure to obtain an epitaxial layer with isolation grooves.

[0083] In the specific execution of S16, the remaining columnar structure can be removed by wet etching to obtain an epitaxial layer with isolation grooves.

[0084] In one embodiment of the present invention, the remaining columnar structure is removed using a BOE solution to obtain an epitaxial layer with isolation grooves.

[0085] like Figure 6 The image shown is a cross-sectional view of an epitaxial layer with isolation grooves provided in an embodiment of the present invention.

[0086] Depend on Figure 6 It can be seen that the epitaxial layer 4 is composed of multiple pillars, and an isolation groove is formed between each pair of adjacent pillars.

[0087] It should be noted that, since the isolation tank is formed by removing... Figure 5 The remaining columnar structure 3 is obtained, that is to say, Figure 6 The width and depth of the central isolation groove are related to Figure 5 The columnar structure 3 includes columns whose width and height correspond. Therefore, in practical applications, it can be adjusted... Figure 5 The remaining columnar structure 3 includes columns with different widths and heights, resulting in isolation grooves of varying widths and depths.

[0088] S17: Chip fabrication is completed based on an epitaxial layer with isolation trenches.

[0089] In the specific execution of S17, a conventional chip is fabricated based on an epitaxial layer with isolation trenches to form a Micro-LED chip.

[0090] In one embodiment of the present invention, the fabrication of a conventional chip based on an epitaxial layer with isolation trenches includes: fabricating at least a conductive extension layer, a second insulating layer, and a metal electrode based on the epitaxial layer with isolation trenches.

[0091] In this embodiment of the invention, by forming and utilizing the tilt of the columnar structure to create a chamfer on the side of the epitaxial layer, there is no need to perform dry etching on the epitaxial layer, thus avoiding damage to the sidewalls of the epitaxial layer and improving the luminous efficiency of the Micro-LED chip based on the epitaxial layer with isolation trenches. At the same time, the chamfer on the side of the epitaxial layer effectively improves the light output brightness of the sidewalls of the Micro-LED chip.

[0092] Based on the Micro-LED chip fabrication method provided in the above embodiments of the present invention, in one embodiment of the present invention, the width of the isolation groove is smaller than the width of the trench.

[0093] That is, the width of the isolation trench obtained by removing the remaining columnar structure is smaller than the width of the trench obtained by photolithography of the insulating layer.

[0094] like Figure 6 As shown, since the epitaxial layer 4 is grown on a trench, the width of the isolation trench is smaller than the width of the pillars included in the epitaxial layer 4.

[0095] In this embodiment of the invention, since the width of the isolation groove is smaller than the width of the trench, it is easier to perform photolithography on the wider trench compared to performing photolithography on the isolation groove with a smaller width, thereby effectively reducing the photolithography difficulty of the micro-LED chip with a small pitch.

[0096] Based on the Micro-LED chip fabrication method provided in the above embodiments of the present invention, the present invention also provides a Micro-LED chip, which is fabricated according to the Micro-LED chip fabrication method provided in the above embodiments of the present invention.

[0097] Specifically, the Micro-LED chip includes a substrate and an epitaxial layer with isolation trenches.

[0098] The epitaxial layer with isolation grooves is obtained by removing the remaining columnar structure, without the need for dry etching.

[0099] The epitaxial layer consists of multiple pillars, with an isolation groove formed between two adjacent pillars, wherein the width of the isolation groove is smaller than the width of the pillar.

[0100] It should be noted that those skilled in the art can design the width difference between the isolation groove and the column according to actual needs.

[0101] In addition, the epitaxial layer may include an N-type GaN layer, a light-emitting layer, and a P-type GaN layer from bottom to top.

[0102] Furthermore, the sides of the epitaxial layer are chamfered.

[0103] Specifically, the side surface of the epitaxial layer may be chamfered relative to a second tilt angle, the second tilt angle being in the range of 30 degrees to 80 degrees.

[0104] In one embodiment of the present invention, the tilt angle of the chamfer formed on the side of the epitaxial layer ranges from 10 degrees to 60 degrees.

[0105] The Micro-LED chip may also include a conductive extension layer based on an epitaxial layer with isolation trenches, a second insulating layer, and metal electrodes.

[0106] In this embodiment of the invention, the epitaxial layer of the Micro-LED chip is not subjected to dry etching, which avoids damage to the sidewalls of the epitaxial layer by plasma during the etching process, thereby improving the luminous efficiency of the Micro-LED chip; at the same time, the sidewalls of the epitaxial layer are chamfered, which effectively improves the light output brightness of the sidewalls of the Micro-LED chip.

[0107] It should be noted that, in the description of this application, the terms "upper," "lower," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. When a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be a component centrally located at the same time.

[0108] It should also be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or apparatus comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or apparatus that includes the aforementioned element.

[0109] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for fabricating a Micro-LED chip, characterized in that, The method includes: Provide a substrate; An insulating layer is grown on the substrate; The insulating layer is photolithographically etched to form multiple trenches and columnar structures with a certain angle; An epitaxial layer is grown on the columnar structure and the trench, and the sides of the epitaxial layer are chamfered. Grind and polish the columnar structure until the surface of the columnar structure is flush with the epitaxial layer in the trench; Remove the remaining columnar structure to obtain an epitaxial layer with isolation grooves; The chip is fabricated based on the epitaxial layer with isolation trenches.

2. The method according to claim 1, characterized in that, Growing an insulating layer on the substrate includes: An insulating layer of SiO2 and / or SiN is grown on the substrate.

3. The method according to claim 1, characterized in that, Photolithography of the insulating layer to form multiple trenches and columnar structures with a certain angle includes: The insulating layer is coated with adhesive, exposed, and developed to form a photolithographic pattern. Photolithography is performed based on the photolithographic pattern of the insulating layer to form multiple trenches and an initial columnar structure with a first tilt angle; The initial columnar structure is etched to form a columnar structure with a second tilt angle, wherein the range of the second tilt angle is a subset of the range of the first tilt angle.

4. The method according to claim 3, characterized in that, The first tilt angle ranges from 0 degrees to 80 degrees; The second tilt angle ranges from 30 degrees to 80 degrees.

5. The method according to claim 3, characterized in that, Photolithography based on the insulating layer photolithography pattern to form multiple trenches and an initial columnar structure with a first tilt angle includes: Photolithography is performed based on the photolithographic pattern of the insulating layer to form multiple trenches and an initial columnar structure with a first tilt angle of 30 degrees; Accordingly, etching the initial columnar structure to form a columnar structure with a second tilt angle includes: The initial columnar structure is etched to form a second columnar structure with an inclination angle of 50 degrees.

6. The method according to claim 3, characterized in that, Growing an epitaxial layer on the columnar structure and the trench, and forming a chamfer on the side surface of the epitaxial layer, includes: An epitaxial layer is grown on the columnar structure and the trench, such that the side surface of the epitaxial layer is chamfered relative to a second tilt angle.

7. The method according to claim 3, characterized in that, Growing an epitaxial layer on the columnar structure and the trench, and forming a chamfer on the side surface of the epitaxial layer, includes: An epitaxial layer is grown on the columnar structure and the trench, such that the side surface of the epitaxial layer has a chamfer with an inclination angle ranging from 10 degrees to 60 degrees.

8. The method according to claim 1, characterized in that, Removing the remaining columnar structure yields an epitaxial layer with isolation grooves, comprising: The remaining columnar structure was removed using BOE solution to obtain an epitaxial layer with isolation grooves.

9. The method according to any one of claims 1 to 8, characterized in that, The width of the isolation groove is smaller than the width of the trench.

10. A Micro-LED chip, characterized in that, The Micro-LED chip is prepared by the method for preparing a Micro-LED chip according to any one of claims 1 to 9.

Images