Micro-LED chip integrated with TFT structure, preparation method of Micro-LED chip and transparent display panel

Abstract

The invention discloses a Micro-LED chip integrated with a TFT structure, a preparation method of the Micro-LED chip and a transparent display panel. The Micro-LED chip comprises a substrate, an epitaxial layer on the substrate and the TFT structure on the epitaxial layer. The epitaxial layer is provided with an n-type electrode and a p-type electrode; the TFT structure comprises a buffer layer, a first dielectric layer and an electrode structure, and a switch, a driver and a capacitor are arranged in the first dielectric layer; the switch comprises a first source electrode, a first grid electrode and a first drain electrode, the driver comprises a second source electrode, a second grid electrode and a second drain electrode, and the electrode structure comprises a switch electrode, a driving electrode and a capacitor electrode; a first lead-out hole is formed in the first dielectric layer; and structures for respectively leading out the first source electrode, the first drain electrode, the second source electrode and the second drain electrode are arranged in the first lead-out hole. According to the invention, the switch circuit, the driver circuit and the capacitor circuit of the TFT structure are directly integrated on the Micro-LED chip, so that the transparency of the display panel can be effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor display chips, and in particular to a Micro-LED chip with an integrated TFT structure, a preparation method thereof, and a transparent display panel. Background Art

[0002] As an emerging display technology, Micro-LED is considered a strong contender for the next generation of display technology due to its advantages such as high brightness, high contrast, low power consumption, fast response and long life. Micro-LED display screens are composed of a large number of micron-sized LED pixels, each of which can be driven independently, so it has higher resolution and wider color gamut.

[0003] Micro-LED transparent display panel is an emerging display technology that can display information without obstructing the line of sight and has broad application prospects, such as smart glass, augmented reality (AR) display, wearable devices, etc. The key to Micro-LED transparent display panel lies in the selection of its substrate material, Micro-LED chip structure and arrangement, and the design of the driving circuit.

[0004] Traditional drive circuit integration methods often result in low transparency of display panels due to the high density of signal metal wires, which affects the overall performance of transparent panels. Therefore, it is necessary to redesign the Micro-LED chip structure and optimize the arrangement of drive circuit metal wires to achieve highly transparent Micro-LED display panels. Summary of the invention

[0005] In order to solve the problems existing in the prior art, the present invention provides a Micro-LED chip with an integrated TFT structure, including a substrate, an epitaxial layer on the substrate, and a TFT structure on the epitaxial layer; The epitaxial layer is provided with an n-type electrode and a p-type electrode; The TFT structure comprises a buffer layer, a first dielectric layer and an electrode structure from bottom to top, wherein a switch, a driver and a capacitor are arranged in the first dielectric layer; the switch comprises a first source, a first gate and a first drain, the driver comprises a second source, a second gate and a second drain, and the electrode structure comprises a switch electrode, a driver electrode and a capacitor electrode connected to the driver electrode, which are arranged above the switch, the driver and the capacitor respectively; A plurality of first lead-out holes are provided in the first dielectric layer, and a first lead-out electrode, a second lead-out electrode, a third lead-out electrode and a fourth lead-out electrode are provided in the first lead-out holes for respectively leading out the first source, the first drain, the second source and the second drain, wherein the second lead-out electrode is connected to the third lead-out electrode, and the fourth lead-out electrode is connected to the p-type electrode.

[0006] Furthermore, the epitaxial layer includes, from bottom to top, an n-type GaN layer, a multi-quantum well active region layer and a p-type GaN layer; An n-type electrode groove directly reaching the n-type GaN layer is provided on one side of the epitaxial layer, and the n-type electrode is provided in the n-type electrode groove; The p-type electrode is disposed on the top of the p-type GaN layer.

[0007] Furthermore, a second dielectric layer for sealing the switch electrode, the drive electrode and the drive electrode is provided on the top of the first dielectric layer, and a second lead-out hole matching the first lead-out hole of the first dielectric layer is provided in the second dielectric layer.

[0008] Furthermore, a passivation layer for sealing the first lead-out electrode, the second lead-out electrode, the third lead-out electrode and the fourth lead-out electrode is disposed on the top of the second dielectric layer, and a third lead-out hole is disposed in the passivation layer.

[0009] Furthermore, the third lead-out hole of the passivation layer is also provided with a V connected to the n-type GaN layer. ss pad, V connected to the first lead-out electrode DATA pad, V connected to the switch electrode scan pad, V connected to the third lead electrode DD Solder pad.

[0010] Furthermore, the thickness of the buffer layer is 200-600 nm; The thickness of the switch, driver and capacitor is 50-100nm; The thickness of the first dielectric layer is 70-200 nm; The thickness of the passivation layer is 200-400 nm.

[0011] The present invention also provides a method for preparing the above-mentioned Micro-LED chip with integrated TFT structure, comprising: Obtaining a Micro-LED wafer, wherein the Micro-LED wafer includes a substrate and an epitaxial layer on the substrate, wherein the epitaxial layer is provided with an n-type electrode and a p-type electrode; A buffer layer and a polysilicon active layer are sequentially prepared on the top of the epitaxial layer, the polysilicon active layer is patterned to form a switch channel, a drive channel and a capacitor, and then a first dielectric layer material and an electrode structure are deposited, and then boron ions are implanted into the polysilicon active layer to form a switch and a drive to obtain an intermediate product; Etching the first dielectric layer material of the intermediate product to form a plurality of first lead-out holes to obtain a first dielectric layer; Metal is deposited in the first lead-out hole to form a first lead-out electrode, a second lead-out electrode, a third lead-out electrode and a fourth lead-out electrode.

[0012] Furthermore, the boron ion implantation energy is 20-100 keV and the implantation dose is 1×10 15 -1×10 17 cm -2 .

[0013] The present invention also provides a transparent display panel, comprising a transparent substrate with a first metal line, and also comprising the above-mentioned Micro-LED chip with an integrated TFT structure; Wherein, the n-type electrode, the first extraction electrode, the switch electrode, and the third extraction electrode of the Micro-LED chip with integrated TFT structure are connected to the first metal wire; The substrate of the Micro-LED chip with integrated TFT structure in the transparent display panel is peeled off, and the epitaxial layer is exposed.

[0014] Furthermore, the peeling is performed by laser peeling, the wavelength of the laser is 200-280nm, and the energy density is 0.6-1.0J / cm 2 .

[0015] Furthermore, a protective layer enclosing the first metal wire is provided on the transparent substrate, a through hole is provided in the protective layer, a second metal wire is provided in the through hole, and the n-type electrode, the first lead electrode, the switch electrode, and the third lead electrode are connected to the first metal wire through the second metal wire.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention directly integrates the switch, drive and capacitor circuits of the TFT structure on the Micro-LED chip. The transparent display panel constructed based on the Micro-LED chip of the present invention can not only reduce the use of active drive backplane, but also reduce the density of metal wire arrangement on the transparent substrate, thereby improving the transparency of the display panel and achieving high-transparency and high-resolution display. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 The preparation process of a Micro-LED chip with an integrated TFT structure is shown; Figure 2 shows a cross-sectional view of a Micro-LED wafer; Figure 3A cross-sectional view of a Micro-LED wafer after preparing an n-type electrode and a p-type electrode is shown; Figure 4 shows a cross-sectional view after preparing a switch channel, a driving channel and a capacitor; Figure 5 A top view of the switch channel, the drive channel and the capacitor is shown; Figure 6 shows a cross-sectional view after depositing a first dielectric material and preparing an electrode structure; Figure 7 A top view of a switch electrode, a drive electrode, and a capacitor electrode is shown; Figure 8 A cross-sectional view of an intermediate product is shown; Fig. 9 shows a cross-sectional view after preparing a second dielectric layer and a first dielectric layer on an intermediate product; Fig.10 shows a cross-sectional view after the lead-out electrode is prepared; Fig.11 A top view of the extraction electrode is shown; Fig.12 A cross-sectional view of a Micro-LED chip with an integrated TFT structure is shown; Fig.13 A schematic structural diagram of a substrate for depositing a first metal line is shown; Fig.14 A schematic diagram of the structure of preparing a first protective layer on a first metal wire is shown; Fig.15 A schematic diagram of the structure after a second metal line is deposited in the first through hole is shown; Fig.16 A schematic diagram showing the structure of preparing a second protective layer on a second metal wire is shown; Fig.17 A schematic structural diagram of a transparent composite substrate is shown; Fig.18 A cross-sectional view showing a Micro-LED chip with an integrated TFT structure bonded to a transparent composite substrate; Fig.19 A schematic structural diagram of a transparent display panel is shown; Description of reference numerals: 101, first substrate; 102, n-type GaN layer; 103, multi-quantum well active region layer; 104, p-type GaN layer; 105, n-type electrode; 106, p-type electrode; 107, buffer layer; 108, switch channel; 109, drive channel; 110, capacitor; 111, first dielectric layer; 112, switch electrode; 113, drive electrode; 114, capacitor electrode; 115, first source; 116, first drain; 117, second source; 118, second drain; 119, second dielectric layer; 120, second extraction hole; 121, first extraction electrode; 122, second extraction electrode; 123, third extraction electrode; 124, fifth extraction electrode; 125, fourth extraction electrode; 126, passivation layer; 127, V ss Pad; 128, V DATA Pad; 129, V scan Pad; 130, V DD Pad; 201, second substrate; 202, first metal wire; 203, first protective layer; 204, first through hole; 205, second metal wire; 206, second protective layer; 207, second through hole; 208, bonding metal layer. DETAILED DESCRIPTION

[0019] The endpoints and any values ​​of the ranges disclosed in the present invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in the present invention.

[0020] In the description of the present application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present application, "plurality" means two or more, unless otherwise clearly and specifically defined.

[0021] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0022] The following will be combined with the specific embodiments of the present invention and the drawings of the specification to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] Example A method for preparing a transparent display panel comprises the following steps: Preparation of Micro-LED chips with integrated TFT structure, such as Figure 1 Shown include, S101, obtain Micro-LED wafers, such as Figure 2 As shown, the Micro-LED wafer includes a first substrate 101 made of sapphire, and an epitaxial layer on the first substrate 101, namely, an n-type GaN layer 102, a multi-quantum well active region layer 103, and a p-type GaN layer 104 arranged in sequence; S102, using photolithography and dry etching technology to prepare a terrace structure on the Micro-LED wafer, etching is performed on one side of the epitaxial layer to obtain an n-type electrode groove that directly reaches the n-type GaN layer 102, and then using photolithography and electron beam evaporation technology to prepare an n-type electrode 105 and a p-type electrode 106 on the top of the n-type electrode groove and the epitaxial layer, such as Figure 3 As shown; and annealed at 600°C for 6 minutes to form an ohmic contact; S103, using ion enhanced chemical vapor deposition (PECVD) technology to deposit 300 nm thick SiO2 and 70 nm thick amorphous Si on the p-type GaN layer 104 in sequence to form a buffer layer 107 made of SiO2, and then performing thermal annealing and dehydrogenation treatment at 500°C, and using XeCl excimer laser annealing technology to convert the amorphous Si film into a polycrystalline silicon active layer, the XeCl excimer laser wavelength is 308 nm, the pulse width is 30 ns, and the energy density is 200 mJ / cm 2 ; Using photolithography and etching techniques to pattern the polysilicon active layer to form a switch channel 108, a drive channel 109 and a capacitor 110, such as Figure 4 and Figure 5 As shown, the driving channel 109 and the capacitor 110 are connected; S104, using PECVD technology to deposit a first dielectric material with a thickness of 120 nm, and then using photolithography and electron beam evaporation to prepare the switch electrode 112, the drive electrode 113, and the capacitor electrode 114 connected to the drive electrode 113, such as Figure 6 As shown; ion implantation technology is then used to implant 1.5×1015 cm -2 The boron ions with a dosage are self-alignedly implanted into the polysilicon active layer to form a first source 115, a first gate, a first drain 116, a second source 117, a second gate and a second drain 118. Figure 7 As shown; then annealing at 450°C for 2 hours to repair the lattice defects caused by ion implantation and make the implanted ions more evenly distributed, thereby obtaining an intermediate product; S105, using PECVD technology to deposit a 500 nm thick second dielectric material on the first dielectric material of the intermediate product, and using photolithography and etching technology to sequentially etch the second dielectric material, the first dielectric layer material and the buffer layer to form a second dielectric layer 119 and a first dielectric layer 111, respectively, wherein the second dielectric layer 119 and the first dielectric layer 111 are provided with a second lead-out hole 120 and a first lead-out hole, respectively, and the n-type electrode and the p-type electrode are exposed at the same time, as shown in FIG. Fig. 9 As shown; S106, using a photolithography process and an electron beam evaporation process, a first lead-out electrode 121, a second lead-out electrode 122, a third lead-out electrode 123, and a fourth lead-out electrode 125 are formed in the first lead-out hole and the second lead-out hole 120 to lead out the first source electrode 115, the first drain electrode 116, the second source electrode 117, and the second drain electrode 118, and a fifth lead-out electrode 124 is formed in the second lead-out hole 120 above the driving electrode 113, wherein the second lead-out electrode 122 is connected to the fifth lead-out electrode 124, and the fourth lead-out electrode 125 is connected to the p-type electrode 106, as shown in FIG. Fig.10 and Fig.11 As shown; S107, using PECVD technology to deposit a 200 nm thick passivation material, and using photolithography and etching technology to obtain a passivation layer 126 with a third lead-out hole; using photolithography and electron beam evaporation technology to deposit Cr / Ni / Au, forming a V connected to the n-type GaN layer in the third lead-out hole; ss The pad 127 and the V connected to the first lead-out electrode DATA The pad 128 and the V connected to the switch electrode scan The pad 129 and the V connected to the third lead-out electrode DD The pad 130 is obtained as Fig.12 Micro-LED chip with integrated TFT structure shown.

[0024] Preparation of transparent composite substrates S201, prepare a second substrate 201 made of glass, and deposit a first metal line 202 on the second substrate 201 by using a photolithography process and an electron beam evaporation process, such as Fig.13 As shown; S202, using PECVD technology to deposit a first protective material with a thickness of 200 nm, and using etching technology to etch a first protective layer 203 with a first through hole 204 in the protective material, such as Fig.14 As shown; S203, depositing the second metal line 205 in the first through hole 204 by using a photolithography process and an electron beam evaporation process, such as Fig.15 As shown; S204, using PECVD technology to deposit a second protective material with a thickness of 200 nm, and using etching technology to etch a second through hole 207 directly reaching the second metal line in the second protective material to obtain a second protective layer 206, such as Fig.16 As shown; S204, depositing a bonding metal layer 208 in the second through hole by using a photolithography process and an electron beam evaporation process, Fig.17 The transparent composite substrate shown; S205, V of the Micro-LED chip with integrated TFT structure ss Pad, V DATA Pad, V scan Pad, V DD The pad is bonded to the bonding metal layer of the transparent substrate, that is, the Micro-LED chip with an integrated TFT structure is bonded to the transparent composite substrate. Fig.18 As shown; S206, KrF excimer laser with a wavelength of 248nm and an energy density of 0.9J / cm 2 The first substrate 101 is peeled off by laser, and the Fig.19 The transparent display panel shown.

[0025] In this embodiment, the first dielectric material, the second dielectric material, the passivation material, the first protective material and the second protective material are made of the same material, which is SiO2. The material of the bonding metal layer is Au-Sn.

[0026] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A Micro-LED chip with an integrated TFT structure, characterized in that: It includes a substrate, an epitaxial layer on the substrate, and a TFT structure on the epitaxial layer; The epitaxial layer is provided with an n-type electrode and a p-type electrode; The TFT structure comprises a buffer layer, a first dielectric layer and an electrode structure from bottom to top, wherein a switch, a driver and a capacitor are arranged in the first dielectric layer; the switch comprises a first source, a first gate and a first drain, the driver comprises a second source, a second gate and a second drain, and the electrode structure comprises a switch electrode, a driver electrode and a capacitor electrode connected to the driver electrode, which are arranged above the switch, the driver and the capacitor respectively; A plurality of first lead-out holes are provided in the first dielectric layer, and a first lead-out electrode, a second lead-out electrode, a third lead-out electrode and a fourth lead-out electrode are provided in the first lead-out holes for respectively leading out the first source, the first drain, the second source and the second drain, wherein the second lead-out electrode is connected to the third lead-out electrode, and the fourth lead-out electrode is connected to the p-type electrode.

2. The Micro-LED chip with integrated TFT structure according to claim 1, characterized in that: The epitaxial layer includes, from bottom to top, an n-type GaN layer, a multi-quantum well active region layer and a p-type GaN layer; An n-type electrode groove directly reaching the n-type GaN layer is provided on one side of the epitaxial layer, and the n-type electrode is provided in the n-type electrode groove; The p-type electrode is disposed on the top of the p-type GaN layer.

3. The Micro-LED chip with integrated TFT structure according to claim 1, characterized in that: A second dielectric layer for sealing the switch electrode, the drive electrode and the drive electrode is also provided on the top of the first dielectric layer, and a second lead-out hole matching the first lead-out hole of the first dielectric layer is provided in the second dielectric layer.

4. The Micro-LED chip with integrated TFT structure according to claim 3, characterized in that: A passivation layer for sealing the first lead-out electrode, the second lead-out electrode, the third lead-out electrode and the fourth lead-out electrode is further provided on the top of the second dielectric layer, and a third lead-out hole is provided in the passivation layer.

5. The Micro-LED chip with integrated TFT structure according to claim 4, characterized in that: The third lead-out hole of the passivation layer is also provided with a V connected to the n-type GaN layer. ss pad, V connected to the first lead-out electrode DATA pad, V connected to the switch electrode scan pad, V connected to the third lead electrode DD Solder pad.

6. The Micro-LED chip with integrated TFT structure according to claim 4, characterized in that: The thickness of the buffer layer is 200-600nm; The thickness of the switch, driver and capacitor is 50-100nm; The thickness of the first dielectric layer is 70-200 nm; The thickness of the passivation layer is 200-400 nm.

7. A method for preparing a Micro-LED chip with an integrated TFT structure as claimed in claim 1, characterized in that: include, Obtaining a Micro-LED wafer, wherein the Micro-LED wafer includes a substrate and an epitaxial layer on the substrate, wherein the epitaxial layer is provided with an n-type electrode and a p-type electrode; A buffer layer and a polysilicon active layer are sequentially prepared on the top of the epitaxial layer, the polysilicon active layer is patterned to form a switch channel, a drive channel and a capacitor, and then a first dielectric layer material and an electrode structure are deposited, and then boron ions are implanted into the polysilicon active layer to form a switch and a drive to obtain an intermediate product; Etching the first dielectric layer material of the intermediate product to form a plurality of first lead-out holes to obtain a first dielectric layer; Metal is deposited in the first lead-out hole to form a first lead-out electrode, a second lead-out electrode, a third lead-out electrode and a fourth lead-out electrode.

8. The method for preparing a Micro-LED chip with an integrated TFT structure according to claim 7, characterized in that: The boron ion implantation energy is 20-100 keV and the implantation dose is 1×10 15 -1×10 17 cm -2 .

9. A transparent display panel, characterized in that: A transparent substrate having a first metal line, and a Micro-LED chip with an integrated TFT structure according to any one of claims 1 to 6; Wherein, the n-type electrode, the first extraction electrode, the switch electrode, and the third extraction electrode of the Micro-LED chip with integrated TFT structure are connected to the first metal wire; The substrate of the Micro-LED chip with integrated TFT structure in the transparent display panel is peeled off, and the epitaxial layer is exposed.

10. The transparent display panel according to claim 9, characterized in that: The transparent substrate is also provided with a protective layer enclosing the first metal wire, the protective layer is provided with a through hole, a second metal wire is provided in the through hole, and the n-type electrode, the first lead electrode, the switch electrode, and the third lead electrode are connected to the first metal wire through the second metal wire.

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