Glass substrate-based micro light emitting diode chip, manufacturing method thereof, and display

Abstract

The present application relates to a glass substrate-based micro light emitting diode chip, comprising: a substrate made of glass; a driving circuit layer formed on the substrate; and a micro light emitting diode array comprising an epitaxial layer, wherein the epitaxial layer is bonded with the driving circuit layer by bonding. The present application also relates to a manufacturing method of the micro light emitting diode chip. Through the chip and / or the method, a mass transfer process can be omitted, thereby improving the process of simplifying the micro light emitting diode chip, improving the yield and reducing the manufacturing cost.

Description

Technical Field

[0001] This disclosure generally relates to the field of micro light-emitting diodes, and more specifically, to a glass-substrate-based micro light-emitting diode chip, a method for manufacturing the same, and a display. Background Technology

[0002] A micro-LED (Micro-Light Emitting Diode) is a novel LED structure created by thinning, miniaturizing, and arraying existing LED structures. It integrates arrayed micron-sized LED units onto an active-addressable driver panel to enable individual illumination and control of each LED unit, thereby outputting the desired display image. The core structure of a micro-LED is a PN junction diode, constructed from a direct bandgap semiconductor material. When a forward bias voltage is applied to the upper and lower electrodes, allowing current to flow, electrons and holes recombine in the active region, simultaneously emitting a single-color photon.

[0003] To drive the tiny light-emitting diodes that serve as pixels, a thin-film transistor (TFT) driving circuit layer is typically used. This allows each pixel to be turned on and off individually, as well as its brightness to be adjusted, thus enabling the entire display to present the desired image conveniently and efficiently.

[0004] Currently, the mainstream manufacturing process for micro LED chips includes the following steps: First, a driving circuit layer is formed on a first substrate; then, a micro LED is formed on a second substrate; next, the micro LED is transferred to the driving circuit layer via mass transfer; finally, the above structure is packaged to form a micro LED chip.

[0005] Mass transfer technology is a crucial step in micro-LED display technology, designed to efficiently and precisely transfer a large number of tiny LED chips from a growth substrate to a target driving substrate to construct high-density, high-quality display arrays. This process involves the transfer of hundreds of thousands or even tens of millions of micro-LEDs. Because micro-LEDs are much smaller than conventional LEDs, the transfer process is extremely challenging, especially in terms of quantity, speed, accuracy, yield, stability, and cost. Furthermore, as the size of micro-LED chips continues to shrink, the alignment accuracy requirements during the transfer process become increasingly stringent, potentially needing to be within ±0.5μm. This necessitates that the micro-LEDs be accurately supported by a temporary substrate, and that the processing precision and flatness of the transfer substrate meet specific parameters to achieve high-yield transfer.

[0006] The use of mass transfer technology makes the manufacturing process of micro LED chips complex and costly, and the complex process also limits the yield rate.

[0007] There is a need for an alternative manufacturing process for miniature light-emitting diode chips. Summary of the Invention

[0008] Based on the prior art, the objective of this invention is to provide a micro light-emitting diode chip based on a glass substrate, a method for manufacturing the same, and a display. By using this chip and / or this method and / or the display, the mass transfer process can be eliminated, thereby simplifying the process of the micro light-emitting diode chip, increasing its yield, and reducing its manufacturing cost.

[0009] In a first aspect of the invention, this task is accomplished by a micro light-emitting diode chip based on a glass substrate, the chip comprising:

[0010] The substrate is made of glass;

[0011] A driving circuit layer is formed on the substrate; and

[0012] A miniature light-emitting diode array, which is bonded to the driving circuit layer.

[0013] In an extended embodiment of the invention, the driving circuit layer is specified as a thin-film transistor driving circuit layer.

[0014] In another extension of the invention, the driving circuit layer is specified to be coupled to the micro LED array in at least one of the following ways:

[0015] Hybrid bonding and full-surface bonding.

[0016] In another extension of the invention, the driving circuit layer is specified to include:

[0017] A conductive circuit layer is formed on the substrate and configured to power the micro light-emitting diode array;

[0018] An insulating layer formed on the conductive circuit layer, wherein the insulating layer has through-holes, and the through-holes have through-hole contacts for electrically connecting the conductive circuit layer to the micro-LED array; and

[0019] A first metal layer is formed on the insulating layer and is electrically connected to the through-hole contact portion.

[0020] In another extension of the invention, the micro-light-emitting diode array further includes:

[0021] A second metal layer is formed on the back side of the epitaxial layer of the micro-LEDs for electrical contact with the epitaxial layer of the micro-LED array.

[0022] In another extension of the invention, the first metal layer and the second metal layer are bonded to each other by metal bonding or hybrid bonding.

[0023] In another extension of the invention, the micro-light-emitting diode array is specified to include a plurality of micro-light-emitting diodes, each micro-light-emitting diode comprising:

[0024] A passivation layer is disposed on the substrate and surrounds the epitaxial layer;

[0025] The epitaxial layer includes a first epitaxial layer, a second epitaxial layer, and a light-emitting layer disposed between the first epitaxial layer and the second epitaxial layer, wherein the first epitaxial layer is disposed above the light-emitting layer and the second epitaxial layer is disposed below the light-emitting layer;

[0026] A transparent electrode layer and a transparent conductive layer cover the passivation layer and are electrically connected to the first epitaxial layer through a first through-hole on the passivation layer. A second through-hole is provided on the bottom side of the micro-light-emitting diode opposite to the first through-hole for leading out the anode of each micro-light-emitting diode.

[0027] The cathode is disposed on the transparent electrode layer and the transparent conductive layer; and

[0028] The anode is disposed on the passivation layer and led out through a second via, wherein the anode is electrically insulated from the transparent electrode layer at the second via.

[0029] In another extension of the present invention, the material of the second epitaxial layer is a material layer of the second conductivity type comprising at least two or more elements of Ga, N, As, Al, In, and P, and the first epitaxial layer is a material layer of the first conductivity type comprising at least two or more elements of Ga, N, As, Al, In, and P, wherein the first conductivity type is different from the second conductivity type.

[0030] In another extension of the present invention, the light-emitting layer is specified to include a multi-quantum-well layer, wherein the multi-quantum-well layer is an InGaN / GaN multi-quantum-well layer, an InGaN / AlGaN multi-quantum-well layer, an InGaAs / AlGaAs multi-quantum-well layer, or an AlGaInP multi-quantum-well layer.

[0031] In another extension of the present invention, an electron blocking layer is provided on the first side of the light-emitting layer, wherein the first side refers to the side along which electrons migrate out of the light-emitting layer.

[0032] In another extension of the invention, the cathode is specified to be made of one or more alloys of the following metals: Ni, Al, Ti, Ni, Pt, Au.

[0033] In another extension of the invention, the material of the passivation layer is specified as a Si3N4 film, a SiO2 film, or an Al2O3 film.

[0034] In another extension of the invention, the driving circuit layer is specified to include at least one of the following:

[0035] 2T1C driver circuit layer, 3T1C driver circuit layer, 5T2C driver circuit layer and 7T1C driver circuit layer, etc.

[0036] In another extension of the invention, the glass comprises:

[0037] Quartz glass, silicate glass, soda-lime glass, and fluoride glass.

[0038] Furthermore, the present invention also relates to a display having a miniature light-emitting diode chip according to the present invention.

[0039] In a second aspect of the invention, the aforementioned objective is achieved by a method for manufacturing a micro light-emitting diode chip based on a glass substrate, the method comprising the following steps:

[0040] Provide a substrate made of glass;

[0041] A thin-film transistor driving circuit layer is formed on a substrate, which includes a first metal layer located on top;

[0042] An epitaxial layer is formed, which includes a second metal layer located at the bottom;

[0043] Bonding the first metal layer and the second metal layer together; and

[0044] Etching the epitaxial layer to form a miniature light-emitting diode chip.

[0045] In another extension of the invention, the first metal layer and the second metal layer are specified to be bonded together by metal bonding.

[0046] In another extension of the invention, the method further includes the step of:

[0047] Etch the first metal layer to structure it;

[0048] Etching the second metal layer to structure it; and

[0049] The first and second metal layers are bonded together by hybrid bonding.

[0050] In another extension of the invention, the method further includes:

[0051] Structure the epitaxial layer to form the light-emitting mesa of each micro-LED; and

[0052] The third metal layer is structured to form the electrode layer of a micro light-emitting diode.

[0053] The present invention has at least the following beneficial effects:

[0054] (1) By using a glass substrate to support the micro LED chip, compared with a silicon substrate, the mechanical strength of the substrate can be improved, thus providing better protection for the micro LED chip; on the other hand, the insulation of the micro LED chip can be improved to prevent leakage current; in addition, glass has a transparent appearance and rich colors, and a glass substrate can make the micro LED chip more beautiful and also provide conditions for its back-lighting function.

[0055] (2) By first bonding the formed epitaxial layer onto the driving circuit layer, and then using the epitaxial layer to form a micro LED chip, the mass transfer process is avoided, which greatly simplifies the process. In addition, by bonding the entire metal surface, the desired electrode layer can be formed, so that only other structures of the micro LED chip need to be formed subsequently. Attached Figure Description

[0056] Figure 1 A schematic diagram of a glass substrate-based micro light-emitting diode chip precursor according to the present invention is shown;

[0057] Figure 2 and Figure 3 Schematic diagrams of a glass substrate-based micro LED chip before and during bonding are shown respectively;

[0058] Figures 4A-4C A schematic diagram of the bonded micro LED chip is shown; and

[0059] Figure 5 The circuit schematic of the 2T1C type drive circuit is shown. Detailed Implementation

[0060] In the following description, the invention is described with reference to various embodiments. However, those skilled in the art will recognize that the embodiments may be practiced without one or more specific details or with other alternatives and / or additional methods, materials, or components. In other instances, well-known structures, materials, or operations are not shown or described in detail so as not to obscure the inventive points of the invention. Similarly, for illustrative purposes, specific quantities, materials, and configurations are set forth to provide a comprehensive understanding of embodiments of the invention. However, the invention is not limited to these specific details. Furthermore, it should be understood that the embodiments shown in the drawings are illustrative representations and are not necessarily drawn to scale.

[0061] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are used only for the convenience of describing the invention and simplifying the description, and do not explicitly or implicitly suggest 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 the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0062] In this specification, references to "an embodiment" or "this embodiment" mean that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment of the invention. The phrase "in one embodiment" appearing throughout this specification does not necessarily refer to the same embodiment in all instances.

[0063] In this invention, the term "configuration" refers to setting the shape, structure, material and / or function of a target object to achieve a desired technical effect. "Configuration" includes a variety of alternative technical means to achieve the technical effect, which become apparent under the teachings of this invention.

[0064] Figure 1 A schematic diagram of a glass substrate-based micro-light-emitting diode chip precursor 100 according to the present invention is shown. Here, the micro-light-emitting diode chip precursor 100 refers to a chip precursor form in which the epitaxial layer has not yet been etched to form a light-emitting mesa.

[0065] like Figure 1 As shown, the glass substrate-based micro light-emitting diode chip precursor 100 according to the present invention includes the following components:

[0066] • Substrate 101, which is made of glass. The material of substrate 101 may include, for example, quartz glass, silicate glass, soda-lime glass, and fluoride glass. By using a glass substrate to support the micro-LED array, compared to a silicon substrate, on the one hand, the mechanical strength of the substrate can be improved, thereby providing better protection for the micro-LED array. On the other hand, compared to a silicon substrate, glass has better insulation properties, thereby improving the insulation of the micro-LED chip and preventing leakage current or interference from external currents.

[0067] • A driving circuit layer 102 is formed on the substrate 101. The driving circuit layer 102 may be a thin-film transistor (TFT) driving circuit layer, and may include 2T1C (two transistors and one capacitor, see [link]). Figure 5 The substrate comprises a driving circuit layer, a 3T1C driving circuit layer (3 transistors and 1 capacitor), and a 5T2C driving circuit layer (5 transistors and 2 capacitors). The driving circuit layer 102 is configured to drive micro-LEDs, for example, controlling the on / off state and brightness of the micro-LEDs. The driving circuit layer 102 may include, for example, transistors, capacitors, a conductive line layer, an insulating layer, and a metal layer. The conductive line layer is formed on the substrate and configured to power the micro-LED array. An insulating layer is formed on the conductive line layer, wherein vias are provided in the insulating layer, and via contacts (e.g., IC copper pillars) are provided in the vias for electrically connecting the conductive line layer to the micro-LED array. The metal layer is used for bonding and electrically contacting the micro-LEDs. The conductive line layer, metal layer, and insulating layer may have been formed on the substrate 101 by deposition, such as physical vapor deposition (PVD) and chemical vapor deposition (CVD). Depending on the specific application, the metal and insulating layers can be patterned using photolithography, and vias can be formed on them. Furthermore, transistors and capacitors in the conductive circuit layer can be formed by deposition and etching. In some embodiments, the driving circuit layer 102 can be electrically connected to each micro-LED in the micro-LED array via individual metal interconnects. In some embodiments, each micro-LED can be electrically controlled individually by the driving circuit layer. In some embodiments, the driving circuit layer 102 can be electrically connected to the electrodes of the micro-LED chip via metal interconnects. In some embodiments, a dielectric layer can be formed in the gaps between the micro-LEDs. In some embodiments, a dielectric layer can also be formed in the gaps between interconnects. Specific examples of the driving circuit layer 102 can be found in [link to relevant documentation]. Figure 2 and Figure 3 The description.

[0068] • An epitaxial layer 103 of the micro-LED array is formed on the driving circuit layer 103 or the substrate 101. The epitaxial layer may include multiple layers formed by epitaxial growth, such as a first epitaxial layer, a second epitaxial layer, and a light-emitting layer located between the first and second epitaxial layers. In this invention, the epitaxial layer 103 specifically refers to a material layer that has been grown but not yet etched to form individual light-emitting mesas. Since the individual light-emitting mesas (i.e., the basic functional units of the micro-LEDs) have not yet been etched, no alignment of the light-emitting mesas is required during the transfer process, thereby simplifying the process. In this invention, the micro-LED array 103 is bonded to the driving circuit layer 102 or the substrate 101 by a bonding process, including full-surface bonding and hybrid bonding. An exemplary formation process for the micro-light-emitting diode 103 includes, for example, depositing an epitaxial layer on a temporary substrate and depositing a metal layer on the epitaxial layer. A composite structure including the metal layer and the epitaxial layer is then transferred to a pre-formed driving circuit layer 102 on the substrate and bonded to the driving circuit layer 102, particularly by metal bonding the metal layer to the metal layer of the driving circuit layer 102. Finally, the composite structure of the epitaxial layer is separated from the temporary substrate. The two bonded metal layers serve as electrode layers (e.g., anodes or electrode layers for electrically connecting the anode to the driving circuit layer) of the micro-light-emitting diode array 103. The epitaxial layer 103 is then etched to form a light-emitting mesa, followed by the deposition of other additional layers, such as a passivation layer, an insulating layer, a transparent conductive layer, a cathode, an anode, and via contacts (e.g., cathode via contacts). Finally, the formed micro-light-emitting diode array is packaged to form a micro-light-emitting diode chip. As can be seen, this process does not require the pre-formation of a complete micro-LED array 103 on a temporary substrate. Instead, it only requires the formation of an epitaxial layer and a bonding layer (such as a metal layer), and then the composite structure is transferred to the already formed driving circuit layer and bonded together. Since the composite structure of the micro-LED does not yet have a fine structure, precise alignment is not required during the transfer and bonding process as in mass transfer processes. Instead, only the bonding layer needs to be aligned, which greatly simplifies the manufacturing process of the micro-LED chip.

[0069] Figure 2 and Figure 3 Schematic diagrams of a glass substrate-based micro-LED chip precursor 100 before and during bonding are shown. Here, the micro-LED chip precursor 100 refers to the chip precursor form in which its epitaxial layer has not yet been etched to form a light-emitting mesa.

[0070] Figure 2 A schematic diagram of the micro LED chip precursor 100 before bonding is shown. Figure 2 As shown, the micro LED chip precursor 100 before bonding only includes a substrate 101 and a driving circuit layer 102. Figure 2and Figure 2 The cell structure of the 2T1C driver circuit layer is illustrated schematically, but this is merely exemplary. In other embodiments, other driver circuit layer architectures may also be used.

[0071] like Figure 2 As shown, the driving circuit layer 102 is formed on the glass substrate 101. For example, a conductive line layer is deposited on the glass substrate 101. The conductive line layer is a stacked structure that includes multiple layers, such as insulating layers 107a-d and 108a-b. As an exemplary 2T1C cell structure, the driving circuit layer 102 also includes two transistors 104a and 104b and one capacitor 105. The transistor 104 may include doped drain and source regions, as well as a gate. The capacitor 105 may include an upper plate and a lower plate. For current or signal conduction through the insulating layer 107, via contacts 106a-g are also provided, which are implemented, for example, as IC copper pillars. The insulating layers 107a-d and 108a-b can be formed on the glass substrate 101 by deposition, such as physical vapor deposition (PVD) and chemical vapor deposition (CVD). Depending on the specific application, insulating layers 108a-b can be patterned by etching and conductive material deposited to form various contacts and circuits, and insulating layers 107a-d can be etched to form via contacts 106a-g. Furthermore, transistors 104a-b and capacitors 105 in the drive circuit layer 102 can be formed by depositing a stack and etching the stack. A first metal layer 109 is formed on top of the drive circuit layer 102 (see...). Figure 3 The first metal layer 109 is disposed on the insulating layer 107d and electrically connected to the via contacts 106h and 106i. The first metal layer 109 can be used to electrically connect the via contacts 106h and 106i, or to bond to the second metal layer 110 of the epitaxial layer 116. The first metal layer 109 may be structured or unstructured. In the case of a structured first metal layer 109, underlying structural layers, such as insulating layers, may be exposed. In this case, the first metal layer 109 will be mixed-bonded with the second metal layer 110, i.e., metal-to-metal bonding and other layer-to-layer bonding. In the case of an unstructured first metal layer 109, the first metal layer 109 will be fully metal-bonded to the second metal layer 110. Metal bonding and mixed bonding can be achieved, for example, by applying pressure and / or heating.

[0072] Figure 3A schematic diagram of a micro LED chip precursor 100 during bonding is shown. Here, the micro LED chip precursor 100 refers to the chip precursor form whose epitaxial layer has not yet been etched to form a light-emitting mesa. After bonding is completed, the micro LED chip precursor 100 is etched to form a light-emitting mesa and additional structures, and finally packaged to form a chip (optionally including wire bonding before packaging).

[0073] Figure 3 and Figure 2 They are basically the same, the main difference is that... Figure 3 An epitaxial layer 116 and a second metal layer 110 of a micro-LED array are shown. The second metal layer 110 is formed on the back side of the epitaxial layer 116 of the micro-LED for electrical contact with the epitaxial layer 116 of the micro-LED array. The second metal layer 110 can be used for electrical contact with the epitaxial layer 116 or for bonding with the first metal layer 109 of the driving circuit layer 102. The second metal layer 110 may be structured or unstructured. In the case of a structured second metal layer 110, the epitaxial layer may be exposed. In this case, the second metal layer 110 will be mixed-bonded with the first metal layer 109, i.e., metal-to-metal bonding and other layers-to-other-layer bonding. In the case of an unstructured second metal layer 110, the second metal layer 110 will be fully metal-bonded with the first metal layer 109. Metal bonding and mixed bonding can be achieved, for example, by applying pressure and / or heating. After bonding is completed, the first metal layer 109 and the second metal layer 110 merge into a third metal layer. The third metal layer can be structured to form the electrode layer of each micro-LED, i.e., used to electrically connect electrodes, such as the anode, to the driving circuit layer. For more information on the bonded micro-LED chips, please refer to [link to relevant documentation]. Figure 4B and Figure 4C As shown in the figure above, since micro LEDs only have epitaxial layers and metal layers and no fine structure during transfer, precise alignment is not required during the transfer and bonding process as in mass transfer processes. Instead, only the bonding layers (such as metal layers) need to be aligned, which greatly simplifies the manufacturing process of micro LED chips.

[0074] Figures 4A-4C A schematic diagram of the bonded miniature light-emitting diode chip 100 is shown, in which... Figure 4A A top view of the miniature light-emitting diode chip 100 is shown. Figure 4B The micro light-emitting diode chip 100 is shown along Figure 4A Cross-sectional view of mid-section line A. Figure 4C The micro light-emitting diode chip 100 is shown along Figure 4A Cross-sectional view of section line B.

[0075] like Figure 4AAs shown, a plurality of miniature light-emitting diodes 103 are formed on a glass substrate 101. A cathode 111 is arranged to surround the miniature light-emitting diodes 103. A signal contact 112 is arranged on one side of the miniature light-emitting diodes 103 and is electrically insulated from the cathode 111. The signal contact 112 is used to contact the anode (see...) Figure 4B and 4C Electrical connections are used to control the power supply to each anode.

[0076] like Figure 4B and 4C As shown, the bonded miniature light-emitting diode chip 100 has the following structure:

[0077] • An etched epitaxial layer 116 is configured to emit light. The epitaxial layer 116 has been etched to form a light-emitting mesa. The epitaxial layer 116 includes a first epitaxial layer, a second epitaxial layer, and a light-emitting layer disposed between the first and second epitaxial layers. The epitaxial layer 116 comprises a first epitaxial layer, a light-emitting layer, and a second epitaxial layer deposited sequentially, wherein the light-emitting layer includes a multiple quantum well layer and an electron blocking layer. In one embodiment of the invention, the first epitaxial layer is an N-type GaN layer or an N-type AlGaN layer, and the second epitaxial layer is a P-type GaN layer or a P-type AlGaN layer. That is, the material of the second epitaxial layer may be a material layer of a second conductivity type comprising at least two or more elements of Ga, N, As, Al, In, and P, and the first epitaxial layer may be a material layer of a first conductivity type comprising at least two or more elements of Ga, N, As, Al, In, and P. The multiple quantum well layer is an InGaN / GaN multiple quantum well layer, an InGaN / AlGaN multiple quantum well layer, or an InGaAs / AlGaAs multiple quantum well layer. The electron blocking device is disposed on a first side of the light-emitting layer, the first side referring to the side along which electrons migrate out of the light-emitting layer. In another embodiment of the present invention, the first epitaxial layer may also be a P-type GaN layer or a P-type AlGaN layer, and the second epitaxial layer may be an N-type GaN layer or an N-type AlGaN layer. In some embodiments, the light-emitting mesa may include, from bottom to top, a first type epitaxial layer, a light-emitting layer, and a second type epitaxial layer. That is, in the three-layer structure, the first type epitaxial layer is closest to the driving circuit layer; the light-emitting layer is located above the first type epitaxial layer and further away from the driving circuit layer; the second type epitaxial layer is located above the light-emitting layer and furthest away from the driving circuit layer. In some embodiments, the light-emitting layer is formed by multiple stacked quantum well layers, particularly superlattice stacked quantum well layers. Preferably, the superlattice stacked quantum well layers include multiple pairs of quantum well layers stacked with quantum barrier layers. In some embodiments, the first type of epitaxial layer is a semiconductor material having a first conductivity type and includes multiple semiconductor layers. The main substrate material of the first type of epitaxial layer may be, but is not limited to, materials such as Ga, N, As, P, In, or Al. Furthermore, the first type of epitaxial layer may, from top to bottom, include, but is not limited to, a waveguide layer, a confinement layer, a transition layer, and a window layer; additionally, an ohmic contact layer may be formed below the window layer. In some embodiments, the second type of epitaxial layer is a semiconductor material having a second conductivity type and includes multiple semiconductor layers. The main substrate material of the second type of epitaxial layer may be, but is not limited to, materials such as Ga, N, As, P, In, or Al. Furthermore, the first type of epitaxial layer may, from top to bottom, include, but is not limited to, a confinement layer and a waveguide layer; additionally, in some embodiments, an ohmic contact layer may be formed on the confinement layer.

[0078] A cathode 111 is electrically connected to the first epitaxial layer of the epitaxial layer 116 via a transparent conductive layer 117 and a cathode contact 114 passing through a passivation layer 115. The cathode 111 can be a ring-shaped reflective electrode, disposed around the epitaxial layer 116. It can be formed, for example, by magnetron sputtering or vapor deposition, and its material can be, for example, Al or Al alloy metal for the sidewall reflective surface. The electrode stack metal can be Ni, Al, Ti, Ni, Pt, Au, or other metal materials. The passivation layer 115 is disposed between the transparent conductive layer 117 and the epitaxial layer 116. Its function is not only to reduce current leakage at the sidewalls, but also to passivate sidewall defects and prevent water, oxygen, etc., from damaging the light-emitting mesa during operation. The material of the passivation layer 115 can be, for example, a Si3N4 film, a SiO2 film, or an Al2O3 film. The passivation layer 115 can be formed, for example, by depositing SiO2 material using a CVD process, or by depositing Al2O3 material using an ALD process. The cathode 111 can be, for example, a common cathode structure, in which an array of miniature light-emitting diodes is connected to a common cathode.

[0079] • An anode 113 is disposed at the bottom of the epitaxial layer 116 to provide power. The anode 113 of each array of micro-LEDs can be selectively connected to the signal contact 112. The common cathode and selective anode connection can form a passive matrix control method to control the on / off state and brightness adjustment of each micro-LED. Here, the anode 113 can be formed, for example, by bonding a first metal layer at the top of the driving circuit layer 102 and a second metal layer at the bottom of the epitaxial layer 116 to form a third metal layer, and structuring the epitaxial layer 116 and the third metal layer (e.g., etching, optionally including thinning) to form a structured epitaxial layer 116 and a third metal layer, the structured epitaxial layer 116 and the third metal layer including the epitaxial layer 116 and the anode 113 of each micro-LED. Additional layers, such as a passivation layer 115, a transparent conductive layer 117, a cathode 111, etc., can then be formed on the already structured epitaxial layer 116 and anode 113. Furthermore, signal contacts 112 can be formed at the blank locations etched in the third metal layer to lead out the anode 113 of the corresponding micro-LED. The transparent conductive layer 117 can be shared by all micro-LEDs in the micro-LED array. In some embodiments, the light-emitting layer may include at least one quantum well layer. The micro-LED chip may include multiple micro-LED arrays, and each micro-LED array may include multiple micro-LEDs. In some embodiments, the micro-LED array may include a single-layer micro-LED structure. In some embodiments, the micro-LED array may include multiple vertically stacked micro-LED structures. In some embodiments, the micro-LED array may include blue micro-LEDs. In some embodiments, the spacing between the micro-LED arrays, i.e., the minimum center-to-center distance between the micro-LEDs, may be between about 2 micrometers and about 50 micrometers. In some embodiments, the number of pixels on the micro-LED chip 100 may be between several thousand and several million.

[0080] The miniature light-emitting diode (LED) chip according to the present invention can be used in various devices including displays, such as monitors, laptops, smartwatches, personal digital assistants (PDAs), mobile phones, and tablets. These devices include the miniature LED chip according to the present invention, a controller (e.g., a microcontroller unit (MCU), a central processing unit (CPU), an application-specific integrated circuit (ASIC), etc.), and optional image processing equipment (e.g., a display adapter card, a graphics processing unit, etc.). Image signals generated by the controller and / or image processing equipment are transmitted to the driving circuit layer of the miniature LED chip. The driving circuit layer optionally decodes the signals to generate matrix row / column pixel signals and optional brightness signals to illuminate the pixels (i.e., miniature LEDs) in the corresponding rows / columns and optionally control their brightness. The illuminated pixels will display the desired image and / or brightness.

[0081] The following describes a method for manufacturing miniature light-emitting diode chips based on glass substrates.

[0082] In step S1, a substrate made of glass is provided.

[0083] In step S2, a thin-film transistor driving circuit layer is formed on the substrate, which includes a first metal layer located on top.

[0084] In step S3, an epitaxial layer is formed, which includes a second metal layer located at the bottom.

[0085] In step S4, the first metal layer and the second metal layer are bonded together to form the third metal layer. For example, the first metal layer and the second metal layer are bonded together over the entire surface by metal bonding. Alternatively, step S4 may include: etching the first metal layer to structure it; etching the second metal layer to structure it; and bonding the first metal layer and the second metal layer together by hybrid bonding.

[0086] In step S5, the epitaxial layer is etched to form a miniature light-emitting diode chip. Step S5 may optionally include: structuring the epitaxial layer to form the light-emitting mesa of each miniature light-emitting diode; and structuring the third metal layer to form the electrode layer of the miniature light-emitting diode.

[0087] Figure 5 The circuit schematic of the 2T1C type drive circuit is shown.

[0088] The 2T1C type drive circuit includes transistors T1 and T2, capacitor C, and a miniature light-emitting diode M. The gate of transistor T1 is connected to the selection signal S, one of its drain and source is connected to the data signal D, and the other of its drain and source is connected to the first plate of capacitor C and the source of transistor T2. One of the drain and source of transistor T2 is connected to the power supply VDD and the second plate of capacitor C, and the other of its drain and source is connected to the first terminal of miniature light-emitting diode M. The second terminal of miniature light-emitting diode M is connected to ground VSS. Transistors T1 and T2 can be n-type or p-type transistors.

[0089] The working principle of the 2T1C type drive circuit is explained below using an n-type transistor as an example.

[0090] When the selection signal S is low, T1 is off, and T2 is turned on or off depending on the level of capacitor C. The miniature LED M is not lit when T2 is off, and is lit when T2 is on.

[0091] When both the selection signal S and the data signal D are high, T1 and T2 are turned on, and capacitor C is charged to a high level. Since capacitor C is at a high level, transistor T1 is turned on for a certain period of time, and the miniature light-emitting diode M remains lit for a certain period of time.

[0092] When the selection signal S is high and the data signal D is low, T1 is turned on and T2 is turned off. The capacitor C discharges to a low level and is reset, and the miniature LED M is not lit.

[0093] Each micro-LED chip has a size not exceeding 1 cm, preferably not exceeding 20 micrometers. The micro-LED structures are formed in an array within the micro-LED chips, with a resolution of, for example, 1200 DPI or 600 DPI. The diameter of the micro-LED structures is in the micrometer range, for example, from 2 micrometers to 50 micrometers.

[0094] While some embodiments of the invention have been described in this application, those skilled in the art will understand that these embodiments are merely illustrative. Numerous variations, alternatives, and improvements will arise in those skilled in the art under the teachings of this invention without departing from its scope. The appended claims are intended to define the scope of the invention and thereby cover the methods and structures within the scope of the claims themselves and their equivalents.

Claims

1. A micro light-emitting diode chip based on a glass substrate, comprising: The substrate is made of glass; A driving circuit layer is formed on the substrate; and A miniature light-emitting diode array, comprising an epitaxial layer, wherein the epitaxial layer is bonded to the driving circuit layer by a bonding process.

2. The micro light-emitting diode chip according to claim 1, wherein the driving circuit layer includes a thin-film transistor driving circuit.

3. The micro LED chip according to claim 1, wherein the driving circuit layer and the epitaxial layer of the micro LED array are bonded together by at least one of the following methods: Hybrid bonding and full-surface bonding.

4. The micro light-emitting diode chip according to claim 1, wherein the driving circuit layer comprises: A conductive circuit layer is formed on the substrate and configured to power the micro light-emitting diode array, wherein the conductive circuit layer has transistors and capacitors; An insulating layer is formed on the conductive circuit layer, wherein the insulating layer has a through hole and the through hole has a through hole contact portion for electrically connecting the conductive circuit layer to the micro light-emitting diode array. as well as A first metal layer is formed on the insulating layer and is electrically connected to the through-hole contact portion.

5. The micro light-emitting diode chip according to claim 4, wherein the micro light-emitting diode array further comprises: A second metal layer is formed on the back side of the epitaxial layer of the micro-LEDs for electrical contact with the epitaxial layer of the micro-LED array.

6. The micro light-emitting diode chip according to claim 5, wherein the first metal layer and the second metal layer are bonded to each other by metal bonding or hybrid bonding.

7. The micro light-emitting diode chip according to claim 4, wherein the micro light-emitting diode array comprises a plurality of micro light-emitting diodes, each micro light-emitting diode comprising: A passivation layer is disposed on the substrate and surrounds the epitaxial layer; The epitaxial layer includes a first epitaxial layer, a second epitaxial layer, and a light-emitting layer disposed between the first epitaxial layer and the second epitaxial layer, wherein the first epitaxial layer is disposed above the light-emitting layer and the second epitaxial layer is disposed below the light-emitting layer; A transparent conductive layer covers the passivation layer and is electrically connected to the first epitaxial layer through a first via on the passivation layer, wherein a second via is provided on the bottom side of the micro-light-emitting diode for leading out the anode of each micro-light-emitting diode; The cathode, which is disposed on a transparent conductive layer; and The anode is led out through the second through hole.

8. The micro light-emitting diode chip according to claim 7, wherein the material of the second epitaxial layer is a material layer of the second conductivity type comprising at least two or more elements including Ga, N, As, Al, In, and P, and the first epitaxial layer is a material layer of the first conductivity type comprising at least two or more elements including Ga, N, As, Al, In, and P, wherein the first conductivity type is different from the second conductivity type.

9. The micro light-emitting diode chip according to claim 7, wherein the light-emitting layer comprises a multi-quantum well layer, wherein the multi-quantum well layer is an InGaN / GaN multi-quantum well layer, an InGaN / AlGaN multi-quantum well layer, an InGaAs / AlGaAs multi-quantum well layer, or an AlGaInP multi-quantum well layer.

10. The micro light-emitting diode chip according to claim 7, wherein an electron blocking layer is provided on the first side of the light-emitting layer, and the first side refers to the side along which electrons migrate out of the light-emitting layer.

11. The micro light-emitting diode chip according to claim 7, wherein the cathode material is one or more alloys of the following metals: Ni, Al, Ti, Ni, Pt, Au.

12. The micro light-emitting diode chip according to claim 7, wherein the material of the passivation layer is a Si3N4 film, a SiO2 film, or an Al2O3 film.

13. The micro light-emitting diode chip according to claim 2, characterized in that, The driving circuit layer includes at least one of the following: 2T1 C drive circuit layer, 3T1 C drive circuit layer, 5T2 C drive circuit layer and 7T1 C drive circuit layer.

14. The micro light-emitting diode chip according to claim 1, characterized in that, The glass comprises: Quartz glass, silicate glass, soda-lime glass, and fluoride glass.

15. A display having a micro light-emitting diode chip according to any one of claims 1 to 14.

16. A method for manufacturing a micro light-emitting diode chip based on a glass substrate, comprising the following steps: Provide a substrate made of glass; A thin-film transistor driving circuit layer is formed on the substrate, which includes a first metal layer located on top; An epitaxial layer is formed, which includes a second metal layer located at the bottom; The first metal layer and the second metal layer are bonded together to form a third metal layer; as well as Etching the epitaxial layer to form a miniature light-emitting diode chip.

17. The method of claim 16, wherein the first metal layer and the second metal layer are bonded together by metal bonding.

18. The method of claim 16, further comprising the step of: Etch the first metal layer to structure it; Etching the second metal layer to structure it; and The first and second metal layers are bonded together by hybrid bonding.

19. The method of claim 16, further comprising: The epitaxial layer is structured to form the light-emitting mesa of each micro LED; as well as The third metal layer is structured to form the electrode layer of a micro light-emitting diode.

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