Microdisplay chip and its fabrication method

Abstract

This application relates to the field of display chip technology, and proposes a microdisplay chip and its fabrication method. The microdisplay chip includes: a driving substrate, a light-emitting structure, a gate structure, and a dielectric layer. The light-emitting structure includes multiple LED mesas, which are spaced apart and arranged on the driving substrate and driven individually by the driving substrate. The gate structure has multiple grid holes, which surround corresponding LED mesas, and the gate structure is higher than the LED mesas. The dielectric layer covers the gate structure and forms multiple corresponding depressions at the grid holes, so that each depression and the corresponding LED mesa form a concave cavity region at the corresponding grid hole, and the highest height of the concave cavity region is lower than that of the gate structure. The dielectric layer includes a microporous dielectric layer and a dense dielectric layer arranged sequentially in the direction away from the driving substrate. By using a dielectric layer with depressions and grid holes to tightly surround the concave cavity region on the LED mesa, the lifespan of the microdisplay chip is improved.

Description

Technical Field

[0001] This application relates to the field of display chip technology, specifically to a microdisplay chip and its fabrication method. Background Technology

[0002] Micro LED, also known as micro light-emitting diode, is a display technology that integrates arrayed micron-sized LED light-emitting units onto an active addressable driver substrate. This allows for individual control and illumination, enabling the output of displayed images. Full-color micro displays have a wide range of applications, especially in near-eye displays (including AR and VR).

[0003] Traditional full-color micro-displays, which directly incorporate light conversion structures into the light-emitting structure, suffer from reduced reliability due to the direct conduction of heat from the LED units to the light conversion structure, which accelerates its aging and failure. Consequently, the lifespan of full-color micro-display devices is limited.

[0004] To improve the reliability of the light conversion structure, Chinese patent document CN119730528A discloses a MicroLED microdisplay chip and its fabrication method. A cavity region is formed by tightly enclosing a first grid hole and an optical layer, reducing the heat conduction of the LED unit to the upper light conversion structure, thus improving the reliability of the light conversion structure and extending the lifespan of the microdisplay chip. However, this patent requires forming a second grid structure on the optical layer and setting multiple light conversion units in the multiple second grid holes of the second grid structure. This significantly increases the overall thickness of the microdisplay chip, hindering the development of chip products towards smaller sizes. Summary of the Invention

[0005] To address the aforementioned issues, this application provides a microdisplay chip and its fabrication method. By using a collapsed dielectric layer to seal concave cavity regions within the grid holes of a gate structure, and filling the collapsed areas of the dielectric layer corresponding to the grid holes with light conversion units, the overall thickness of the chip product is reduced, the reliability of the light conversion units is improved, and the lifespan of the microdisplay chip is extended.

[0006] The technical solution adopted in this application is as follows: In a first aspect, a microdisplay chip is provided, comprising: a driving substrate, a light-emitting structure, a gate structure, and a dielectric layer; The light-emitting structure includes multiple LED mesa surfaces, which are arranged at intervals on the driving substrate and are driven individually by the driving substrate. The fence structure has multiple grid holes, which surround corresponding LED platforms, and the fence structure is higher than the LED platforms. The dielectric layer covers the fence structure and forms multiple corresponding depressions at multiple grid holes, so that each depression and the corresponding LED platform form a concave cavity area at the corresponding grid hole, and the highest height of the concave cavity area is lower than the fence structure. The dielectric layer includes a microporous dielectric layer and a dense dielectric layer arranged sequentially in the direction opposite to the driving substrate.

[0007] Optionally, each LED mesa includes: a first electrode layer, an epitaxial layer disposed on the first electrode layer, and a passivation layer disposed on the sidewalls of the first electrode layer and the epitaxial layer; the multiple first electrode layers corresponding to the multiple LED mesa are respectively connected to multiple first contacts of the driving substrate; A second electrode layer is covered on multiple LED mesa and a driving substrate; the second electrode layer is connected to the epitaxial layer of each LED mesa and to the second contact of the driving substrate; the second electrode layer has a light-emitting hole at the epitaxial layer of each LED mesa.

[0008] Optionally, the fence structure includes: a light-blocking substrate and a reflective layer disposed on the surface of the light-blocking substrate; The light-blocking substrate has multiple grid holes; The reflective layer is provided at least on the sidewall of the grid aperture.

[0009] Optionally, the dielectric layer may be made of silicon dioxide.

[0010] Optionally, the microdisplay chip also includes: multiple light conversion units respectively filled in multiple collapses; Multiple optical conversion units include at least: a first optical conversion unit and a second optical conversion unit; The first light conversion unit converts the light passing through the dielectric layer into light of the first color. The second light conversion unit converts the light passing through the dielectric layer into light of the second color.

[0011] Optionally, the multiple light conversion units may also include: a transparent unit; The transparent unit transmits light through the dielectric layer.

[0012] Optionally, the plurality of optical conversion units may further include: a third optical conversion unit; The third light conversion unit converts the light passing through the dielectric layer into a third color light.

[0013] Secondly, a method for fabricating a microdisplay chip is provided, comprising: Provide driving substrate; A light-emitting structure is formed, which includes multiple LED mesa, which are arranged at intervals on a driving substrate and are driven individually by the driving substrate. A fence structure is formed, which has multiple grid holes, each surrounding a corresponding LED platform, and the fence structure is higher than the LED platform. A dielectric layer is formed, which covers the fence structure and forms multiple corresponding depressions at multiple grid holes, so that each depression and the corresponding LED platform form a concave cavity area at the corresponding grid hole, and the highest height of the concave cavity area is lower than the fence structure. The dielectric layer includes a microporous dielectric layer and a dense dielectric layer arranged sequentially in the direction opposite to the driving substrate.

[0014] Optionally, the fence structure includes: A light-blocking substrate material layer is formed on the light-emitting structure; The light-blocking substrate material layer is etched to form multiple grid holes surrounding multiple LED mesa, thus obtaining the light-blocking substrate; A reflective material layer is formed on the light-emitting structure and the light-blocking substrate; The reflective material layer is etched to form a reflective layer at least on the sidewalls of the grid holes.

[0015] Optionally, a dielectric layer is formed, including: Multiple photoresist fills are formed within multiple grid holes, and each photoresist fill forms a concave shape. Dielectric material layers are formed on multiple photoresist-filled and fence structures using inductively coupled plasma chemical vapor deposition. Multiple photoresist fillers are removed to form a microporous structure in the dielectric material layer, resulting in a microporous dielectric layer. A dense dielectric layer is formed on a microporous dielectric layer by atomic layer deposition.

[0016] Optionally, the fabrication method further includes: forming multiple light conversion units; Multiple optical conversion units are formed, including: Multiple collapses are respectively filled with light conversion materials; wherein the light conversion materials include at least a first light conversion material and a second light conversion material; A first light conversion material is filled into the partially collapsed area to form a first light conversion unit, so as to convert the light passing through the dielectric layer into light of the first color. A second light conversion unit is formed by filling the partially collapsed area with a second light conversion material to convert light passing through the dielectric layer into light of a second color.

[0017] The above-mentioned technical solution adopted in this application can achieve the following beneficial effects: The chip provided in this application includes: a driving substrate, a light-emitting structure, a gate structure, and a dielectric layer; the light-emitting structure includes multiple LED mesas, which are spaced apart on the driving substrate and driven individually by the driving substrate; the gate structure has multiple grid holes, which surround the corresponding multiple LED mesas, and the gate structure is higher than the multiple LED mesas; the dielectric layer covers the gate structure and forms multiple corresponding depressions at the multiple grid holes, so that each depression and the corresponding LED mesa form a concave cavity region at the corresponding grid hole, and the highest height of the concave cavity region is lower than that of the gate structure; the dielectric layer includes a microporous dielectric layer and a dense dielectric layer arranged sequentially in the direction away from the driving substrate.

[0018] The microdisplay chip proposed in this application forms a concave cavity region at the corresponding grid hole due to the collapse of the dielectric layer and the LED mesa. The air in the cavity region has extremely low thermal conductivity, which reduces the heat generated by the LED mesa and conducts it to the light conversion unit above, effectively improving the reliability of the light conversion unit and increasing the service life of the microdisplay chip.

[0019] The microdisplay chip proposed in this application can tightly enclose the concave cavity region on the LED mesa by having a collapsed dielectric layer and grid holes. The fabrication process is simple, does not require too much complex compaction, and has a high product yield.

[0020] The microdisplay chip proposed in this application fills the light conversion unit within the collapse of the dielectric layer, which greatly reduces the overall thickness of the chip and is conducive to the development of chip products towards smaller sizes.

[0021] The microdisplay chip proposed in this application provides a microporous dielectric layer that provides basic support for the concave cavity region, ensuring the stability of the collapsed shape. A dense dielectric layer provides a tight seal for the concave cavity region, forming a thermally insulating space and preventing the subsequent filling of light conversion materials from penetrating into the microporous dielectric layer or the cavity region. Furthermore, the dense dielectric layer is deposited only after the microporous dielectric layer is fully formed. At this point, the surface of the microporous dielectric layer is a stable solid interface, and the pore size is much smaller than the diffusion scale of precursor molecules in atomic layer deposition. The precursor cannot enter the interior of the micropores and can only be uniformly deposited on the outer surface of the microporous dielectric layer, forming a surface-attached dense dielectric layer, thus creating a clear physical interface. Attached Figure Description

[0022] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This diagram illustrates the structure of a microdisplay chip according to an embodiment of the present application. Figure 2A schematic diagram of the structure of a microdisplay chip according to another embodiment of this application is shown; Figure 3 A schematic diagram of the structure of a microdisplay chip according to another embodiment of this application is shown; Figure 4 A schematic flowchart illustrating a method for fabricating a microdisplay chip according to an embodiment of this application is shown. Figure 5 This diagram illustrates the structure after the light-emitting structure has been formed according to an embodiment of this application. Figure 6 This diagram illustrates the structure of a light-blocking substrate formed according to an embodiment of the present application. Figure 7 This diagram shows a schematic representation of the formation of a reflective layer according to an embodiment of this application. Figure 8 This diagram illustrates a structure after photoresist filling according to one embodiment of the present application. Figure 9 This diagram illustrates the structure after forming a dielectric material layer according to an embodiment of the present application. Figure 10 A schematic diagram of the structure after forming a microporous dielectric layer according to an embodiment of this application is shown; Figure 11 This diagram illustrates the structure after forming a dense dielectric layer according to an embodiment of the present application. Detailed Implementation

[0023] Exemplary embodiments of this application will now be described in more detail. However, it should be understood that this application may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of this application and to fully convey the scope of this application to those skilled in the art.

[0024] This application discloses numerous different embodiments or examples for implementing various structures. To simplify the disclosure, specific examples of components and arrangements are described herein. These are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. Additionally, this application provides examples of various specific processes and materials, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0025] Generally, terms can be understood at least in part according to their usage in the preceding application. For example, the term "one or more" as used in this application, which is at least in part dependent on the preceding application, can be used to describe any component, structure, or feature in the singular, or to describe a combination of components, structures, or features in the plural. Similarly, terms such as "a," "an," or "the" can also be understood, at least in part dependent on the preceding application, to convey either a singular or a plural usage. Furthermore, the term "based on..." can be understood not necessarily to convey an exclusive set of factors, but rather, alternatively, at least in part dependent on the context, allowing for additional factors that do not necessarily have to be explicitly described.

[0026] It should be noted that, in the description of this application, the terms “on,” “above,” “on top of,” “above,” etc., should be interpreted in the broadest sense, meaning that a description containing these terms is interpreted as “a component may be disposed on another component in direct contact, or there may be an intermediate component or layer between the components.”

[0027] For ease of description, this application may also use spatial relative terms such as “under,” “below,” “below,” “below,” “upper,” and “lower” to describe the relationship between one component and another component shown in the accompanying drawings. In addition to the orientations described in the drawings, the spatial relative terms are also intended to cover different orientations of the device during use or operation. The device may be oriented in other ways, and the spatial relative descriptions used in this application can be interpreted accordingly.

[0028] Figure 1 A schematic diagram of the structure of a microdisplay chip according to an embodiment of this application is shown. Figure 1 The horizontal direction can correspond to the cross-sectional extension direction of the microdisplay chip, and the vertical direction can correspond to the ideal beam propagation direction of the microdisplay chip.

[0029] Reference Figure 1 The microdisplay chip in this embodiment may include: a driving substrate 1, a light-emitting structure 2, a fence structure 3, and a dielectric layer 4.

[0030] The light-emitting structure 2 includes: multiple LED mesa 21, which are arranged at intervals on the driving substrate 1 and are driven individually by the driving substrate 1.

[0031] The fence structure 3 has multiple grid holes, which surround the corresponding multiple LED platforms 21. The fence structure 3 is higher than the multiple LED platforms 21.

[0032] The dielectric layer 4 covers the fence structure 3 and forms multiple corresponding depressions at multiple grid holes, so that each depression and the corresponding LED platform 21 form a concave cavity area at the corresponding grid hole, and the highest height of the concave cavity area is lower than that of the fence structure 3.

[0033] The dielectric layer 4 includes a microporous dielectric layer 41 and a dense dielectric layer 42 arranged sequentially in the direction opposite to the driving substrate 1.

[0034] The driving substrate 1 may include a substrate 11, a driving circuit, and multiple contacts connected to the driving circuit. The driving substrate 1 may have a circuit layer, including a silicon-based CMOS (Complementary Metal Oxide Semiconductor) backplane, a TFT glass substrate, or a thin-film field-effect transistor, to form the driving circuit. The material of the substrate 11 may include semiconductor materials such as silicon, silicon carbide, gallium nitride, germanium, gallium arsenide, and cobalt phosphide; it may also include non-conductive materials such as glass, plastic, and sapphire wafers.

[0035] Multiple LED mesa 21 can be arranged on the driving substrate 1 in a regular or irregular manner. The driving substrate 1 can refer to the control panel of the multiple LED mesa 21. The driving substrate 1 generates driving signals based on the image to be displayed and applies them to the multiple LED mesa 21, so that each LED mesa 21 independently releases a light beam in response to the driving signals.

[0036] The LED display panel 21 can be a miniature light-emitting diode (LED) or a miniature organic light-emitting diode (OLED). The miniature LED is formed based on inorganic semiconductor materials, such as gallium nitride, aluminum gallium nitride, gallium arsenide, and aluminum gallium indium phosphide. The miniature OLED is formed based on organic materials, such as small molecules, polymers, and phosphorescent materials.

[0037] Each LED platform 21 can be trapezoidal in shape. That is, the sidewalls of the LED platform 21 can be sloping, and the angle between the sidewalls and the top surface of the LED platform 21 can be obtuse, thereby improving the light-focusing effect of the LED platform 21. Of course, the LED platform 21 can also be columnar, in which case the angle between the sidewalls and the top surface of the LED platform 21 is a right angle.

[0038] The microdisplay device can be a common cathode structure, a common anode structure, or each can be independent.

[0039] In some optional implementations, each LED mesa 21 may include a first electrode layer 211, an epitaxial layer 212 disposed on the first electrode layer 211, and a passivation layer 213 disposed on the sidewalls of the first electrode layer 211 and the epitaxial layer 212; the multiple first electrode layers 211 corresponding to the multiple LED mesa 21 are respectively connected to the multiple first contacts 12 of the driving substrate 1; a second electrode layer 22 covers the multiple LED mesa 21 and the driving substrate 1; the second electrode layer 22 is connected to the epitaxial layer 212 of each LED mesa 21, the second electrode layer 22 is connected to the second contact 13 of the driving substrate 1, and the second electrode layer 22 has a light-emitting hole at the epitaxial layer 212 of each LED mesa 21.

[0040] In this case, multiple LED platforms 21 form a common cathode structure through a common cathode—the second electrode layer 22.

[0041] For an LED platform 21, its first electrode layer 211 is connected to a first contact 12 of the driving substrate 1. The material of the first electrode layer 211 can be a metal or metal alloy, including indium tin oxide, chromium, platinum, gold, aluminum, germanium, tin, indium, copper or titanium, etc.

[0042] An epitaxial layer 212 is disposed on the first electrode layer 211. The epitaxial layer 212 may include a first doped semiconductor layer, a light-emitting layer, and a second doped semiconductor layer stacked together. The first doped semiconductor layer may be a p-type GaN or InGaN layer formed by doping or ion implantation, etc., and the first doped semiconductor layer may be a multilayer structure. The second doped semiconductor layer may be an n-type GaN or InGaN layer formed by doping or ion implantation, etc., and the second doped semiconductor layer may also be a multilayer structure. The light-emitting layer is a layer that outputs light of a specific wavelength based on the recombination of holes provided by the first doped semiconductor layer and electrons provided by the second doped semiconductor layer. The light-emitting layer may have a single quantum well structure or a multiple quantum well (MQW) structure, and may also have well layers and barrier layers stacked alternately.

[0043] The passivation layer 213 covers the sidewalls of the first electrode layer 211 and the epitaxial layer 212. The material of the passivation layer 213 may include inorganic or organic materials. Inorganic materials may include, but are not limited to, any one or a combination of silicon dioxide, aluminum oxide, zirconium dioxide, titanium dioxide, silicon nitride, and hafnium oxide; organic materials include any one or a combination of black matrix photoresist, color filter photoresist, polyimide, bank, overcoat, near-ultraviolet negative photoresist, and styrene.

[0044] A second electrode layer 22 is covered on multiple LED mesa 21 and the driving substrate 1. The second electrode layer 22 is connected to the epitaxial layer 212 of each LED mesa 21 and to the second contact 13 of the driving substrate 1. The second electrode layer 22 has a light-emitting hole corresponding to the epitaxial layer 212 of each LED mesa 21. The material of the first electrode layer 211 can be a metal or metal alloy, including indium tin oxide, chromium, platinum, gold, aluminum, germanium, tin, indium, copper, or titanium, etc.

[0045] The second electrode layer 22 can also be a conductive, highly transparent thin film material, which may include: indium tin compounds, conductive SiO2, conductive PI, molybdenum, silver, etc. In this case, the second electrode layer 22 may not have a light-emitting hole at the epitaxial layer 212 corresponding to each LED mesa 21.

[0046] The light-emitting structure 2 has a grid structure 3. The grid structure 3 has multiple grid holes that correspond one-to-one with the LED platform 21. That is, the multiple grid holes can be arranged in a regular or irregular manner according to the arrangement of the multiple LED platforms 21. In order to improve the uniformity of light emission of each LED platform 21, each LED platform 21 can be set at the center of the corresponding grid hole.

[0047] The sidewalls of the grid holes can be vertical surfaces, such as... Figure 1 As shown. The sidewalls of the grid holes can also be beveled, and the angle between the sidewalls of the grid holes and the top surface of the grid structure 3 is an obtuse angle, i.e., the direction away from the driving substrate 1. The cross-sectional dimensions of the grid holes can gradually increase. Generally, this cross-section can be a circular cross-section or a square cross-section, and of course, it can also be an irregularly shaped cross-section. The structure of the grid holes can be a bowl-shaped structure or a horn-shaped structure, so that the emitted light from the LED mesa 21 can be collimated. When the sidewalls of the LED mesa 21 are set as bevels and the sidewalls of the grid holes are also set as bevels, the light can be reflected multiple times on the bevels of both, thereby improving the luminous brightness of the LED mesa 21.

[0048] The height of the fence structure 3 is higher than that of the multiple LED platforms 21. That is, the height of the top surface of the fence structure 3 is higher than the height of the top surface of each LED platform 21.

[0049] In some alternative implementations, the fence structure 3 includes: a light-blocking substrate 31 and a reflective layer 32 disposed on the surface of the light-blocking substrate 31; the light-blocking substrate 31 has a plurality of grid holes; the reflective layer 32 is disposed at least on the sidewall of the grid holes.

[0050] The grid structure 3 can be formed using a light-blocking substrate material. The light-blocking substrate material has grid holes at positions corresponding to each LED platform 21, and a reflective layer 32 is provided at least on the sidewalls of the grid holes. The reflective layer 32 can also be provided on the top surface of the light-blocking substrate 31.

[0051] The material of the light-blocking substrate 31 may include, but is not limited to, organic resin, organic black matrix photoresist, color filter photoresist, or polyimide. The material of the reflective layer 32 may include, but is not limited to, organic or inorganic materials. Organic materials may be highly reflective organic coatings, and inorganic materials may be metallic materials such as aluminum, copper, or silver.

[0052] The reflective layer 32 in the fence structure 3 can effectively prevent light leakage from the sidewalls of each LED platform 21, thereby effectively preventing light crosstalk between adjacent LED platforms 21. At the same time, the fence structure 3 also plays a role in heat conduction, preventing the heat generated by the LED material from being concentrated and conducted to the light conversion material.

[0053] In some alternative embodiments, an etch barrier layer may be covered on the light-emitting structure 2 to isolate the second electrode layer 22 and the fence structure 3 and to prevent etching damage to the light-emitting structure 2.

[0054] The etching barrier layer can be a continuous film structure located between the fence structure 3 and the light-emitting structure 2. The etching barrier layer can transmit light emitted from multiple LED mesa 21, therefore it should possess sufficient transparency. Generally, the material of the etching barrier layer can include, but is not limited to, silicon dioxide, silicon nitride, or aluminum oxide.

[0055] A dielectric layer 4 is covered on the fence structure 3. The dielectric layer 4 forms multiple corresponding depressions at multiple grid holes, so that each depression and the corresponding LED platform 21 form a concave cavity area at the corresponding grid hole, and the highest height of the concave cavity area is lower than that of the fence structure 3; the dielectric layer 4 includes: a microporous dielectric layer 41 covering the fence structure 3 and a dense dielectric layer 42 covering the microporous dielectric layer 41.

[0056] For each LED mesa 21, the collapse of the dielectric layer 4 and the corresponding grid apertures form a sealed concave cavity region. The air in this concave cavity region has extremely low thermal conductivity. In a sealed state, the thermal conductivity of air is only 0.024 W / m·K. Therefore, by using the sealed concave cavity region, the heat generated by the LED material is reduced from being conducted to the light conversion material above, effectively improving the lifespan of the microdisplay chip.

[0057] For the depression formed at the grid hole of the dielectric layer 4, its outline shape can be designed as an arc-shaped depression or a right-angled depression according to actual needs. Both depression shapes can be combined with the LED table 21 and the grid hole to form a concave cavity area that meets the heat insulation requirements.

[0058] The arc-shaped collapse is a continuous and smooth curved surface structure. The curvature of the surface can be adapted to the light emission angle of the LED mesa 21 and the size of the grid holes. The smooth arc-shaped structure can avoid stress concentration at the corners of the dielectric layer 4, improve the structural stability of the dielectric layer 4, and reduce the risk of stress cracking during processing or chip use.

[0059] The right-angle collapse is formed by connecting mutually perpendicular planes to create a right-angled profile. This shape results in a regular spatial contour of the concave cavity region, facilitating the subsequent filling and curing of the light conversion material within the collapse and avoiding uneven accumulation of the material on curved surfaces. To ensure that the dielectric layer 4 forms a collapse and creates a sealed concave cavity region at the corresponding grid aperture, photoresist is used to fill the grid aperture before forming the dielectric layer 4. During the formation of the dielectric layer 4, the photoresist filler 6 is removed to form the concave cavity region.

[0060] Specifically, photoresist can be used to form concave fillings within multiple grid holes. Inductively coupled plasma chemical vapor deposition (ICP-CVD) is used to form a dielectric material layer 7 on the photoresist filling 6 and the gate structure 3. During the removal of the photoresist filling 6, the dielectric material layer 7 forms a microporous structure, resulting in a microporous dielectric layer 41. To ensure the airtightness of the concave cavity region, an atomic layer deposition (ALD) is used to cover the microporous dielectric layer 41 with a dense dielectric layer 42.

[0061] The material of dielectric layer 4 can be a transparent inorganic oxide material, such as silicon dioxide.

[0062] The dielectric layer 4 also serves to transmit light emitted from the multiple LED mesa 21. Furthermore, in the case where the microdisplay chip further includes multiple light conversion units 5 filling the depressions within the dielectric layer 4, the dielectric layer 4 also serves to reflect the light whose colors have been converted by the multiple light conversion units 5.

[0063] The microporous dielectric layer 41 is a silicon dioxide layer formed by inductively coupled plasma chemical vapor deposition on the basis of photoresist concave filling within the grid holes. After the photoresist is removed, the silicon dioxide layer will form a collapsed structure and micropores following the concave contour of the photoresist. The microporous dielectric layer 41 covers the entire grid structure, ensuring the stability of the collapsed shape and providing a continuous deposition substrate for the subsequent atomic layer deposition of the dense dielectric layer 42.

[0064] The dense dielectric layer 42 is a silicon dioxide layer prepared by atomic layer deposition on the microporous dielectric layer 41, serving as a reinforcing layer to ensure the sealing of the concave cavity region. Because the microporous dielectric layer 41 has micropores due to the removal of photoresist, it cannot achieve complete sealing of the concave cavity region. However, the non-porous, dense structure of the dense dielectric layer 42 can seal all micropores and gaps in the microporous dielectric layer 41, creating a completely sealed thermally insulated space in the concave cavity region. This prevents airflow from reducing the thermal insulation effect and also prevents external moisture and impurities from entering the cavity or contacting the underlying light-emitting structure, thus improving the chip's environmental stability.

[0065] The dense dielectric layer 42 is deposited on the collapsed surface of the microporous dielectric layer 41. Its high density can fix the geometry of the collapsed layer and prevent the material from penetrating into the microporous dielectric layer 41 or the concave cavity region when the light conversion material is filled in later.

[0066] The microporous dielectric layer 41 is prepared by inductively coupled plasma chemical vapor deposition (ICP-CVD), which rapidly deposits a film through a gas-phase reaction. The film particles have relatively large gaps between them, resulting in loose micropores after the photoresist is removed. The dense dielectric layer 42 is prepared by atomic layer deposition (ALD), which forms a film through atomic-level layer-by-layer deposition and chemical reaction. During the deposition process, precursor molecules are adsorbed and reacted one by one on the surface of the microporous dielectric layer 41, resulting in a film layer that is non-porous and extremely dense.

[0067] The dense dielectric layer 42 is deposited after the microporous dielectric layer 41 is fully formed and the photoresist is removed. At this time, the surface of the microporous dielectric layer 41 is a stable solid interface, and the pore size of the micropores is much smaller than the diffusion scale of the precursor molecules in atomic layer deposition. The precursor cannot enter the interior of the micropores and can only be uniformly deposited on the outer surface of the microporous dielectric layer 41 to form a dense dielectric layer 42 attached to the surface, thereby forming a clear physical interface.

[0068] Figure 2 and Figure 3 A schematic diagram of the structure of a microdisplay chip proposed in another and yet another embodiment of this application is shown.

[0069] Reference Figure 2 and Figure 3 As shown, the microdisplay chip of this embodiment, based on the microdisplay chip proposed in the previous embodiment, further includes: a plurality of light conversion units 5 respectively filled in a plurality of depressions; the plurality of light conversion units 5 include at least: a first light conversion unit 51 and a second light conversion unit 52; the first light conversion unit 51 converts the light passing through the dielectric layer 4 into a first color light; the second light conversion unit 52 converts the light passing through the dielectric layer 4 into a second color light.

[0070] Multiple light conversion units 5 are respectively disposed in multiple depressions of the dielectric layer 4 corresponding to multiple grid holes, such that each light conversion unit 5 is disposed on an LED platform 21. Each light conversion unit 5 fills at least part or all of the corresponding depression.

[0071] Among the multiple light conversion units 5, some light conversion units 5 are first light conversion units 51, and some light conversion units 5 are second light conversion units 52. That is to say, the first light conversion unit 51 and the second light conversion unit 52 are respectively disposed in different collapses.

[0072] The materials of the light conversion unit 5 include photoresist and wavelength conversion particles, which may be, but are not limited to, quantum dots and / or phosphors. The photoresist includes, but is not limited to, overcoat photoresist, SU8 (near-ultraviolet negative photoresist), benzocyclobutene (BCB), etc., and may also be silicon dioxide, aluminum oxide, silicon nitride, etc. The phosphor may be yttrium aluminum garnet, cerium phosphor, (oxy)nitride phosphor, silicate phosphor, and Mn4+ activated fluoride phosphor, etc. The quantum dots may include one or more combinations of CdSe, CdS, CdZnSe, CdZnS, CdZnSeS, ZnSeS, ZnSe, CuInS, CuInSe, InP, InZnP, and perovskite quantum dots.

[0073] Light emitted from the LED platform 21 passes through the dielectric layer 4 and enters the first light conversion unit 51, where it is converted into a first color light. The first color light can be red, and in this case, the first light conversion unit 51 uses a red wavelength conversion material. Light emitted from the LED platform 21 then passes through the dielectric layer 4 and enters the second light conversion unit 52, where it is converted into a second color light. The second color light can be green, and in this case, the second light conversion unit 52 uses a green wavelength conversion material.

[0074] Reference Figure 2 As shown, in some optional embodiments, the plurality of light conversion units 5 further include: a transparent unit 53; the transparent unit 53 transmits light through the dielectric layer 4.

[0075] In some cases, the light emitted by the LED platform 21 is blue light. In this case, only the blue light emitted by the LED platform 21 needs to be transmitted through the transparent unit 53. Therefore, a transparent unit 53 is provided in the collapsed area where the first light conversion unit 51 and the second light conversion unit 52 are not provided, so that the blue light emitted by the LED platform 21 can be directly transmitted. One pixel unit corresponds to at least one LED platform 21 filled with the first light conversion unit 51, one LED platform 21 filled with the second light conversion unit 52, and one LED platform 21 filled with the transparent unit 53, thus achieving full-color display.

[0076] Reference Figure 3 As shown, in some optional embodiments, the plurality of light conversion units 5 further include: a third light conversion unit 54; the third light conversion unit 54 converts the light passing through the dielectric layer 4 into a third color light.

[0077] In some cases, the light emitted by the LED mesa 21 is not blue light. In this case, the light emitted by the LED mesa 21 enters the third light conversion unit 54 after passing through the dielectric layer 4, where it is converted into a third color light. The third color light can be blue light, and in this case, the third light conversion unit 54 uses a blue wavelength conversion material.

[0078] The first, second, and third colors of light are all different. The first, second, and third colors of light can also be set to other colors according to actual needs. Each pixel unit corresponds to at least one LED platform 21 filling the first light conversion unit 51, one LED platform 21 filling the second light conversion unit 52, and one LED platform 21 filling the third light conversion unit 54, thus achieving full-color display.

[0079] Figure 4 A schematic flowchart illustrating a method for fabricating a microdisplay chip according to an embodiment of this application is shown. (Refer to...) Figure 4 The preparation method proposed in this application includes the following steps: Step S1, provide driving substrate 1; Step S2: Forming a light-emitting structure 2, which includes multiple LED mesa 21. The multiple LED mesa 21 are arranged at intervals on the driving substrate 1 and are driven individually by the driving substrate 1.

[0080] Step S3: Form a fence structure 3. The fence structure 3 has multiple grid holes, which surround the corresponding multiple LED platforms 21. The fence structure 3 is higher than the multiple LED platforms 21.

[0081] Step S4: Form a dielectric layer 4. The dielectric layer 4 covers the fence structure 3 and forms multiple corresponding depressions at multiple grid holes, so that each depression and the corresponding LED platform 21 form a concave cavity area at the corresponding grid hole. The highest height of the concave cavity area is lower than that of the fence structure 3. The dielectric layer 4 includes a microporous dielectric layer 41 and a dense dielectric layer 42 arranged sequentially in the direction opposite to the driving substrate 1.

[0082] Figures 5 to 10 This diagram illustrates the different stages in the fabrication process of a microdisplay chip. See also... Figures 5 to 10 This paper provides a detailed introduction to the methods for fabricating microdisplay chips.

[0083] Figure 5A schematic diagram of the structure after the formation of the light-emitting structure 2 is shown. See also some embodiments of this application. Figure 5 Forming a light-emitting structure 2, comprising: A substrate is provided, an epitaxial material is grown on the substrate, and a first bonding material is grown on the epitaxial material.

[0084] A driving substrate 1 is provided. The driving substrate 1 may be provided with a circuit layer including a silicon-based CMOS backplane, a TFT glass substrate, or a thin-film field-effect transistor, etc., to form a driving circuit. The driving substrate 1 also includes a plurality of contacts connected to the driving circuit. The plurality of contacts include a plurality of first contacts 12 and second contacts 13. A second bonding material is grown on the driving substrate 1.

[0085] Epitaxial materials, first bonding materials, and second bonding materials can be formed by deposition.

[0086] The first and second bonding materials are metallically bonded together, and the substrate is then peeled off from the epitaxial material. Substrate peeling methods include, but are not limited to, laser peeling, dry etching, wet etching, and mechanical polishing.

[0087] Thinning operations are performed on epitaxial materials, including dry etching, wet etching, or mechanical polishing.

[0088] Based on the MESA pattern designed using a patterned mask, the epitaxial material is etched, followed by the etching of the bonding material. The etched epitaxial material forms multiple epitaxial layers 212, and the etched bonding material forms multiple first electrode layers 211. Each first electrode layer 211 is connected to each first contact 12, and each epitaxial layer 212 is located on each first electrode layer 211. The etching can be performed using either a dry or wet etching method.

[0089] Passivation layers 213 are deposited on the side surfaces of multiple epitaxial layers 212 and multiple first electrode layers 211 to form multiple LED mesa 21. Second electrode material is deposited on the multiple LED mesa 21 and the driving substrate 1, and the second electrode material is etched to form light-emitting holes at the epitaxial layers 212 corresponding to each LED mesa 21, forming a second electrode layer 22. The second electrode layer 22 connects each epitaxial layer 212 and a second contact 13, thereby forming a light-emitting structure 2.

[0090] Figures 6 to 7 A schematic diagram of the structure after the fence structure 3 is formed is shown. See also some embodiments of this application. Figures 6 to 7The process of forming a fence structure 3 includes: forming a light-blocking substrate material layer on the light-emitting structure 2; etching the light-blocking substrate material layer to form multiple grid holes surrounding multiple LED platform 21 to obtain a light-blocking substrate 31; forming a reflective material layer on the light-emitting structure 2 and the light-blocking substrate 31; and etching the reflective material layer to form a reflective layer 32 at least on the sidewalls of the grid holes.

[0091] A light-blocking substrate material layer can be formed on the light-emitting structure 2. The light-blocking substrate material layer is etched to form a light-blocking substrate 31 with multiple grid holes. The multiple grid holes surround multiple LED mesa 21. Figure 6 As shown.

[0092] A reflective material layer is formed on the light-emitting structure 2 and the light-blocking substrate 31. The reflective material layer can be deposited using methods such as atomic layer deposition (ALD), chemical vapor deposition (CVD), evaporation, and sputtering. The reflective material layer on the light-emitting structure 2 is etched to form a reflective layer 32 on the sidewalls of the grid holes and the top surface of the light-blocking substrate 31. Etching can be performed using dry etching methods, including but not limited to ion beam etching (IBE) and inductively coupled plasma etching (ICP). Dry etching allows for full-surface etching after the reflective material layer is deposited, ensuring the reflective material on the light-emitting structure 2 is completely etched away. Simultaneously, during etching, the reflective material layer undergoes a plasma redeposition effect, resulting in a thicker reflective material layer on the sidewalls of the grid holes, enhancing the reflective effect and strengthening the stability of the fence structure 3. Figure 7 As shown.

[0093] In some embodiments of this application, before forming the fence structure 3, the preparation method may further include: forming an etching barrier layer; wherein the etching barrier layer covers the light-emitting structure 2 to isolate the second electrode layer 22 and the fence structure 3 and to prevent etching damage to the light-emitting structure 2.

[0094] Figures 8 to 11 A schematic diagram of the structure after the formation of dielectric layer 4 is shown. See also some embodiments of this application. Figures 8 to 11 The process of forming a dielectric layer includes: forming multiple photoresist fillers 6 within multiple grid holes, each photoresist filler 6 forming a concave shape; forming a dielectric material layer 7 on the multiple photoresist fillers 6 and the gate structure 3 using inductively coupled plasma chemical vapor deposition; removing the multiple photoresist fillers 6 to form a microporous structure in the dielectric material layer 7, resulting in a microporous dielectric layer 41; and forming a dense dielectric layer 42 on the microporous dielectric layer 41 using atomic layer deposition.

[0095] The grid holes of the fence structure 3 are filled with photoresist. Each photoresist filler 6 forms a concave shape, and the maximum height of the concave shape is lower than the top of the fence structure 3. For example... Figure 8 As shown.

[0096] A dielectric material layer 7 is formed on the photoresist filler 6 and the gate structure 3. The dielectric material layer 7 can be a transparent inorganic oxide material, such as silicon dioxide. The dielectric material layer 7 is deposited via inductively coupled plasma chemical vapor deposition. Figure 9 As shown.

[0097] Multiple photoresist fillers 6 are removed by development. During the removal process, the dielectric material layer 7 forms a microporous structure, resulting in a microporous dielectric layer 41. After the photoresist fillers 6 are removed, each collapsed microporous dielectric layer 41 and the corresponding LED mesa 21 form a concave cavity region at the corresponding grid hole. Figure 10 As shown.

[0098] A dense dielectric layer 42 is formed on the microporous dielectric layer 41. The dense dielectric layer 42 is deposited by atomic layer deposition. Figure 11 As shown.

[0099] Figures 2 to 3 A schematic diagram of the structure after forming multiple optical conversion units 5 is shown. See also some embodiments of this application. Figures 2 to 3 The preparation method further includes: forming a plurality of light conversion units 5; forming a plurality of light conversion units 5 includes: filling a plurality of collapses with light conversion materials respectively; wherein the light conversion materials include at least: a first light conversion material, a second light conversion material and a transparent material; filling a partial collapse with the first light conversion material to form a first light conversion unit 51, so as to convert light passing through the dielectric layer 4 into first color light; filling a partial collapse with the second light conversion material to form a second light conversion unit 52, so as to convert light passing through the dielectric layer 4 into second color light; filling a partial collapse with the transparent material to form a transparent unit 53, so as to transmit light passing through the dielectric layer 4.

[0100] When the LED tabletop 21 emits blue light, such as Figure 2 As shown, a first light conversion material can be filled into the collapsed area. The first light conversion material can be filled by spin coating and drying.

[0101] The area where the first light conversion unit 51 needs to be formed is illuminated by light. The area where the first light conversion unit 51 needs to be formed can be exposed by blocking other areas with a mask layer.

[0102] The mask layer is removed, and the first light conversion material is developed using a developing solution. Since only the area of ​​the first light conversion unit 51 is photocured, the rest is removed under the action of the developing solution, thereby forming the first light conversion unit 51 within the partial collapse, which converts the blue light emitted by the corresponding LED platform 21 into red light.

[0103] A second light conversion unit 52 can be formed in some of the collapsed areas to convert the blue light emitted by the corresponding LED platform 21 into green light; transparent units 53 can be formed in other collapsed areas to directly transmit the blue light emitted by the corresponding LED platform 21. That is, different light conversion units 5 are formed in different collapsed areas. This realizes a full-color micro-display chip.

[0104] In some embodiments of this application, the preparation method further includes: forming a plurality of light conversion units 5; forming a plurality of light conversion units 5 includes: filling a plurality of depressions with light conversion materials respectively; wherein the light conversion materials include at least: a first light conversion material, a second light conversion material, and a third light conversion material; filling a partial depression with the first light conversion material to form a first light conversion unit 51, so as to convert light passing through the dielectric layer 4 into first color light; filling a partial depression with the second light conversion material to form a second light conversion unit 52, so as to convert light passing through the dielectric layer 4 into second color light; filling a partial depression with the third light conversion material to form a third light conversion unit 54, so as to convert light passing through the dielectric layer 4 into third color light.

[0105] If the LED tabletop 21 does not emit blue light, such as Figure 3 As shown, a first light conversion material can be filled into the collapsed area. The first light conversion material can be filled by spin coating and drying.

[0106] The area where the first light conversion unit 51 needs to be formed is illuminated by light. The area where the first light conversion unit 51 needs to be formed can be exposed by blocking other areas with a mask layer.

[0107] The mask layer is removed, and the first light conversion material is developed using a developing solution. Since only the area of ​​the first light conversion unit 51 is photocured, the rest is removed under the action of the developing solution, thereby forming the first light conversion unit 51 within the partial collapse, which converts the light emitted from the corresponding LED platform 21 into red light.

[0108] A second light conversion unit 52 can be formed in some of the collapsed areas to convert the light emitted from the corresponding LED platform 21 into green light; a third light conversion unit 54 can be formed in other collapsed areas to convert the light emitted from the corresponding LED platform 21 into blue light. That is, different light conversion units 5 are formed in different collapsed areas. This realizes a full-color micro-display chip.

[0109] The preparation method proposed in this application uses photoresist to form concave fillings in each grid hole, deposits a dielectric material layer on multiple photoresist fillings and grid structures, and then seals the concave cavity region by developing and removing the photoresist.

[0110] The fabrication method proposed in this application only requires the formation of a single grid structure. A concave cavity region is formed downwards within each grid aperture using a dielectric layer, and each light conversion unit is formed upwards.

[0111] Compared with existing technologies, such as Chinese patent document CN119730528A, the preparation method proposed in this application not only improves the reliability of the light conversion unit and extends the service life of the micro display chip, but also greatly reduces the thickness of the micro display chip, which is conducive to the development of chips towards smaller sizes.

[0112] The microdisplay chip proposed in this application provides a microporous dielectric layer that provides basic support for the concave cavity region, ensuring the stability of the collapsed shape. A dense dielectric layer provides a tight seal for the concave cavity region, forming a thermally insulating space and preventing the subsequent filling of light conversion materials from penetrating into the microporous dielectric layer or the cavity region. Furthermore, the dense dielectric layer is deposited only after the microporous dielectric layer is fully formed. At this point, the surface of the microporous dielectric layer is a stable solid interface, and the pore size is much smaller than the diffusion scale of precursor molecules in atomic layer deposition. The precursor cannot enter the interior of the micropores and can only be uniformly deposited on the outer surface of the microporous dielectric layer, forming a surface-attached dense dielectric layer, thus creating a clear physical interface.

[0113] The above description is merely a specific embodiment of this application. Under the teachings of this application, those skilled in the art can make other improvements or modifications based on the above embodiments. Those skilled in the art should understand that the above specific description is only to better explain the purpose of this application, and the scope of protection of this application should be determined by the scope of the claims.

[0114] Furthermore, those skilled in the art will understand that although some embodiments described herein include certain features but not others included in other embodiments, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, in the following claims, any of the claimed embodiments can be used in any combination.

Claims

1. A microdisplay chip, characterized in that, The microdisplay chip includes: a driving substrate, a light-emitting structure, a gate structure, and a dielectric layer; The light-emitting structure includes multiple LED mesa surfaces, which are arranged at intervals on the driving substrate and are driven individually by the driving substrate. The fence structure has multiple grid holes, which respectively surround the corresponding multiple LED platforms, and the fence structure is higher than the multiple LED platforms; The dielectric layer covers the fence structure and forms multiple corresponding depressions at the multiple grid holes, so that each depression and the corresponding LED platform form a concave cavity area at the corresponding grid hole, and the highest height of the concave cavity area is lower than the fence structure. The dielectric layer includes a microporous dielectric layer and a dense dielectric layer arranged sequentially in the direction opposite to the driving substrate.

2. The microdisplay chip according to claim 1, characterized in that, Each of the LED platforms includes: a first electrode layer, an epitaxial layer disposed on the first electrode layer, and a passivation layer disposed on the sidewalls of the first electrode layer and the epitaxial layer; the multiple first electrode layers corresponding to the multiple LED platforms are respectively connected to the multiple first contacts of the driving substrate; A second electrode layer is covered on the plurality of LED mesa and the driving substrate; the second electrode layer is connected to the epitaxial layer of each LED mesa, the second electrode layer is connected to a second contact of the driving substrate, and the second electrode layer has a light-emitting hole corresponding to the epitaxial layer of each LED mesa.

3. The microdisplay chip according to claim 1, characterized in that, The fence structure includes: a light-blocking substrate and a reflective layer disposed on the surface of the light-blocking substrate; The light-blocking substrate has a plurality of the aforementioned grid holes; The reflective layer is provided at least on the sidewall of the grid aperture.

4. The microdisplay chip according to claim 1, characterized in that, The dielectric layer is made of silicon dioxide.

5. The microdisplay chip according to claim 1, characterized in that, The microdisplay chip further includes: a plurality of light conversion units respectively filled within the plurality of said collapses; The plurality of optical conversion units include at least: a first optical conversion unit and a second optical conversion unit; The first light conversion unit converts the light passing through the dielectric layer into light of the first color; The second light conversion unit converts the light passing through the dielectric layer into light of a second color.

6. The microdisplay chip according to claim 5, characterized in that, The plurality of light conversion units further include: a transparent unit; The transparent unit transmits light that has passed through the dielectric layer.

7. The microdisplay chip according to claim 5, characterized in that, The plurality of optical conversion units further include: a third optical conversion unit; The third light conversion unit converts the light passing through the dielectric layer into a third color light.

8. A method for fabricating a microdisplay chip, characterized in that, The preparation method includes the following steps: Provide driving substrate; A light-emitting structure is formed, the light-emitting structure including a plurality of LED mesa, the plurality of LED mesa being arranged at intervals on the driving substrate and driven individually by the driving substrate; A fence structure is formed, the fence structure having multiple grid holes, the multiple grid holes respectively surrounding the corresponding multiple LED platforms, and the fence structure being higher than the multiple LED platforms; A dielectric layer is formed, which covers the fence structure and forms a plurality of corresponding depressions at the plurality of grid holes, such that each depression and the corresponding LED platform form a concave cavity area at the corresponding grid hole, the highest height of the concave cavity area being lower than the fence structure; The dielectric layer includes a microporous dielectric layer and a dense dielectric layer arranged sequentially in the direction opposite to the driving substrate.

9. The method for fabricating a microdisplay chip according to claim 8, characterized in that, The formation of the fence structure includes: A light-blocking substrate material layer is formed on the light-emitting structure; The light-blocking substrate material layer is etched to form a plurality of grid holes surrounding the plurality of LED platforms, thereby obtaining the light-blocking substrate; A reflective material layer is formed on the light-emitting structure and the light-blocking substrate; The reflective material layer is etched to form a reflective layer at least on the sidewalls of the grid holes.

10. The method for fabricating a microdisplay chip according to claim 8, characterized in that, The formation of the dielectric layer includes: Multiple photoresist fillers are formed within the multiple grid holes, and each photoresist filler forms a concave shape; A dielectric material layer is formed on the multiple photoresist fillers and the fence structure using inductively coupled plasma chemical vapor deposition. Remove multiple photoresist fillers to form a microporous structure in the dielectric material layer, thereby obtaining the microporous dielectric layer; The dense medium layer is formed on the microporous medium layer by atomic layer deposition.

11. The method for fabricating a microdisplay chip according to claim 8, characterized in that, The preparation method further includes: forming multiple light conversion units; The formation of multiple optical conversion units includes: Each of the multiple collapses is filled with a light conversion material; wherein the light conversion material includes at least a first light conversion material and a second light conversion material; The first light conversion material is filled into a portion of the collapsed area to form a first light conversion unit, so as to convert light passing through the dielectric layer into light of a first color. The second light conversion material is filled into a portion of the collapsed area to form a second light conversion unit, so as to convert light passing through the dielectric layer into second color light.

Images