A nitride full-color integrated micro light-emitting diode display chip and its fabrication method

Abstract

This invention discloses a nitride-based full-color integrated micro-LED display chip and its fabrication method. A columnar or truncated mesa is formed on the surface of a silicon substrate. Then, an AlN buffer layer, an AlGaN stress modulation layer, an n-type GaN layer, an InGaN / GaN composite quantum well layer, and a p-type conductive layer are sequentially epitaxially grown on the silicon substrate mesa to form the micro-LED mesa. Through stress release on the mesa sidewalls and stress modulation of the AlGaN layer, a tensile stress distribution that gradually decreases from the center to the outer edge of the mesa is formed in the n-type GaN layer, thereby controlling the indium composition distribution in the InGaN / GaN composite quantum well layer and forming a micro-LED mesa covering the red, green, and blue primary color bands. The chip structure disclosed in this invention integrates red, green, and blue primary color sub-pixels, reducing the difficulty of mass transfer processes for full-color micro-LED display chips. This invention only requires one epitaxial process to complete the fabrication of the red, green, and blue primary color sub-pixels, simplifying the process flow.

Description

Technical Field

[0001] This invention relates to the field of full-color micro light-emitting diode display technology, and in particular to a nitride full-color integrated micro light-emitting diode display chip and its fabrication method. Background Technology

[0002] Miniature LED display technology boasts advantages such as low power consumption, long lifespan, and excellent color rendering, making it a promising candidate for applications in large-screen displays, consumer electronics, automotive displays, virtual reality / augmented reality, and wearable displays. Achieving full-color display is one of the challenges facing miniature LED display technology. Currently, mass transfer methods are commonly used to transfer red, green, and blue primary color miniature LED chips onto the same substrate to achieve full-color display.

[0003] Typically, full-color micro LED displays require millions of red, green, and blue primary color pixels. Accurately transferring and integrating so many micro LED chips is extremely difficult, making it hard to improve the yield of mass transfer processes. This limits the development of full-color micro LED display technology. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the purpose of this invention is to provide a nitride full-color integrated micro light-emitting diode display chip and its preparation method. The chip structure integrates red, green and blue primary color sub-pixels, which greatly reduces the technical difficulty of mass transfer of full-color display chips.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] A nitride full-color integrated micro light-emitting diode display chip includes: a transparent substrate, a transparent electrode bonding layer, and a mesa array composed of one or more micro light-emitting diode mesas;

[0007] The micro LED mesa or the mesa array is connected to the transparent substrate through the transparent electrode bonding layer.

[0008] Preferably, the micro LED mesa is columnar or trapezoidal; the width of the micro LED mesa ranges from 100 nm to 100 μm; and the spacing between the mesa segments ranges from 100 nm to 100 μm.

[0009] Preferably, the structure of the micro light-emitting diode mesa includes, in sequence from the transparent substrate and the transparent electrode bonding layer: an n-type transparent electrode layer, an n-type GaN layer, one or more cycles of InGaN / GaN composite multiple quantum well layers, a p-type conductive layer, and a p-type electrode layer.

[0010] Preferably, the n-type GaN layer exhibits a tensile stress distribution trend that gradually decreases from the center of the mesa to the outer ring.

[0011] Preferably, each InGaN / GaN composite multi-quantum-well layer comprises: a plurality of high-indium-content InGaN / GaN quantum wells and a plurality of low-indium-content InGaN / GaN quantum wells; the central region of the micro-LED mesa is dominated by the high-indium-content InGaN / GaN quantum wells for luminescence; and the outer region of the micro-LED mesa is dominated by the low-indium-content InGaN / GaN quantum wells for luminescence.

[0012] Preferably, from the center region to the outer ring region of the micro-LED mesa, the indium composition of the InGaN potential well layer in the InGaN / GaN composite multi-quantum well layer shows a gradually decreasing distribution trend; from the center region to the outer ring region of the micro-LED mesa, the emission wavelength of the high-indium-content InGaN / GaN quantum well gradually blue-shifts from 630nm to 550nm; from the center region to the outer ring region of the micro-LED mesa, the emission wavelength of the low-indium-content InGaN / GaN quantum well gradually blue-shifts from 550nm to 450nm.

[0013] Preferably, the emission wavelength range of the micro-LED mesa covers the red, green, and blue primary color bands; the emission regions corresponding to the red, green, and blue primary color bands in the micro-LED mesa are distributed in a ring shape; the ring-shaped region with an emission center wavelength range of 610 to 630 nm in the micro-LED mesa is the red photonic pixel region; the ring-shaped region with an emission center wavelength range of 510 to 530 nm in the micro-LED mesa is the green photonic pixel region; and the ring-shaped region with an emission center wavelength range of 450 to 470 nm in the micro-LED mesa is the blue photonic pixel region.

[0014] Preferably, the p-type conductive layer comprises: a p-type AlGaN electron blocking layer and a p-type GaN layer;

[0015] The p-type conductive layer located between the red photonic pixel region, the green photonic pixel region, and the blue photonic pixel region is transformed into a high-resistivity layer through ion implantation; the p-type conductive layer located on the red photonic pixel region, the green photonic pixel region, and the blue photonic pixel region is not subjected to ion implantation treatment.

[0016] Preferably, the p-type electrode layer is distributed in a ring shape;

[0017] The p-type electrode layer is located on the surface of the p-type conductive layer that has not undergone ion implantation treatment.

[0018] Preferably, a method for fabricating a nitride full-color integrated micro light-emitting diode display chip includes:

[0019] S1. Provide a raw silicon substrate with a (111) crystal plane.

[0020] S2. Using photolithography and etching processes, the surface of the original silicon substrate from step S1 is etched into a columnar or truncated array of silicon substrate mesas; the height of the mesas in the silicon substrate mesas array ranges from 10 μm to 100 μm; the width of the silicon substrate mesas array ranges from 10 μm to 100 μm; the spacing of the silicon substrate mesas array ranges from 10 μm to 100 μm.

[0021] S3. Using a metal-organic chemical vapor deposition (MOCVD) apparatus, an AlN buffer layer, an AlGaN stress modulation layer, and an n-type GaN layer are sequentially epitaxially grown onto the silicon substrate mesa array prepared in step S2 to obtain an n-type GaN mesa array. The structural parameters of the AlGaN stress modulation layer are adjusted according to the stress release effect of the mesa sidewalls, so that the n-type GaN mesa prepared in step S3 is in a tensile stress state with a high center and low outer ring distribution. The structure of the AlGaN stress modulation layer includes one or more of the following: a uniform composition AlGaN structure, a graded composition AlGaN structure, an AlN / AlGaN superlattice structure, an AlGaN / GaN superlattice structure, and an AlN / GaN superlattice structure.

[0022] S4. One or more cycles of the InGaN / GaN composite multiple quantum well layer are epitaxially formed on the n-type GaN mesa array prepared in step S3. Each cycle of the InGaN / GaN composite multiple quantum well layer includes: a number of high indium content InGaN / GaN quantum wells and a number of low indium content InGaN / GaN quantum wells.

[0023] S5. Epitaxially grow the p-type conductive layer on the InGaN / GaN composite multiple quantum well layer in step S4 to obtain a nitride micro light-emitting diode mesa array; the p-type conductive layer includes: the p-type AlGaN electron blocking layer and the p-type GaN layer;

[0024] S6. Based on the principle that tensile stress promotes the incorporation of indium atoms into the lattice, by optimizing the morphology parameters of the silicon substrate mesa in step S2 and the structural parameters of the AlGaN stress modulation layer in step S3, the tensile stress distribution trend of the n-type GaN mesa in step S3 is controlled, so that the indium composition of the InGaN potential well layer of the InGaN / GaN composite multi-quantum well layer prepared in step S4 gradually decreases from the central region of the mesa to the outer region; the epitaxial growth of the InGaN / GaN composite multi-quantum well layer in step S4 is optimized. The long parameters cause the emission wavelength of the high-indium-content InGaN / GaN quantum well to gradually blue-shift from 630nm to 550nm from the center region to the outer ring region of the micro-LED mesa formed in steps S1 to S5, and the emission wavelength of the low-indium-content InGaN / GaN quantum well to gradually blue-shift from 550nm to 450nm; the emission wavelength of the micro-LED mesa formed in steps S1 to S5 covers the red, green, and blue primary color bands for display applications from the center region to the outer ring region of the mesa;

[0025] S7. Determine the red photonic pixel region, the green photonic pixel region, and the blue photonic pixel region; the light-emitting regions corresponding to the red, green, and blue primary color bands in the micro-LED mesa are distributed in a ring shape; the ring-shaped region in the micro-LED mesa with a light-emitting center wavelength range of 610 to 630 nm is the red photonic pixel region; the ring-shaped region in the micro-LED mesa with a light-emitting center wavelength range of 510 to 530 nm is the green photonic pixel region; the ring-shaped region in the micro-LED mesa with a light-emitting center wavelength range of 450 to 470 nm is the blue photonic pixel region;

[0026] S8. Using photolithography, metal evaporation and lift-off processes, deposit annular p-type electrode layers on the red photonic pixel region, the green photonic pixel region and the blue photonic pixel region of the micro light-emitting diode mesa prepared in steps S1 to S6.

[0027] S9. Using the p-type electrode layer prepared in step S8 as a mask, perform ion implantation to transform the unmasked area between the red photonic pixel region, the green photonic pixel region, and the blue photonic pixel region into the high-resistivity layer.

[0028] S10. Bond the micro-light-emitting diode mesa array prepared in step S9 onto a temporary substrate;

[0029] S11. Use an alkaline etching solution to remove the original silicon substrate and fix the micro light-emitting diode mesa array on the temporary substrate;

[0030] S12. Using photolithography and etching processes, remove the AlN buffer layer and the AlGaN stress modulation layer from the micro light-emitting diode mesa in step S11;

[0031] S13. Using photolithography, metal evaporation and lift-off processes, deposit the n-type transparent electrode layer and the transparent electrode bonding layer on the n-type GaN layer exposed in step S12;

[0032] S14. The micro light-emitting diode mesa array, on which the n-type transparent electrode layer and the transparent electrode bonding layer are deposited, is bonded onto the transparent substrate;

[0033] S15. Remove the temporary substrate from step S10;

[0034] S16. The micro-light-emitting diode mesa array on the transparent substrate prepared in steps S1 to S15 is cut into chips; each chip includes: a single or several silicon substrate mesa arrays composed of the micro-light-emitting diode mesa.

[0035] The present invention discloses the following technical effects:

[0036] This invention provides a nitride-based full-color integrated micro-light-emitting diode (LED) display chip and its fabrication method. By integrating red, green, and blue primary color sub-pixels onto the same micro-LED mesa, this invention solves the problem of mass transfer difficulties in full-color micro-LED display chips, achieving high pixel density full-color micro-LED displays and improving full-color mixing effects. Through the vertically structured micro-LED mesa, it overcomes the problems of poor injection efficiency and photoelectric performance in conventional LED chips, achieving stronger luminous intensity and photoelectric performance. Furthermore, the designed chip fabrication method solves the problem of low chip yield caused by multiple epitaxy processes in conventional chips, enabling the fabrication of red, green, and blue InGaN / GaN composite multiple quantum wells based on a single epitaxial process. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 A schematic diagram of a nitride full-color micro light-emitting diode display chip provided in an embodiment of the present invention;

[0039] Figure 2A cross-sectional schematic diagram of a nitride full-color micro light-emitting diode display chip provided in an embodiment of the present invention;

[0040] Figure 3 A top view schematic diagram of a nitride full-color micro light-emitting diode display chip provided in an embodiment of the present invention;

[0041] Figure 4 This is a cross-sectional schematic diagram of a silicon substrate surface etched into a mesa array according to an embodiment of the present invention;

[0042] Figure 5 This is a cross-sectional schematic diagram of a micro-light-emitting diode structure epitaxially grown on a mesa array of a silicon substrate, as provided in an embodiment of the present invention.

[0043] Figure 6 This is a top view of the epitaxial nitride micro light-emitting diode structure on a silicon substrate mesa array provided in an embodiment of the present invention.

[0044] Figure 7 This is a cross-sectional schematic diagram of the red, green, and blue sub-pixel regions of a micro-light-emitting diode mesa provided in an embodiment of the present invention.

[0045] Figure 8 This is a top view schematic diagram of the deposition of p-type electrode layers on the red, green, and blue sub-pixel regions of a micro-light-emitting diode mesa, as provided in an embodiment of the present invention.

[0046] Figure 9 This is a cross-sectional schematic diagram of a miniature light-emitting diode mesa array after isolating red, green, and blue primary color sub-pixel devices under a p-type electrode layer mask, as provided in an embodiment of the present invention.

[0047] Figure 10 This is a cross-sectional schematic diagram of a micro-light-emitting diode mesa array bonded to a temporary substrate, as provided in an embodiment of the present invention.

[0048] Figure 11 A cross-sectional schematic diagram of a micro-light-emitting diode mesa array after etching away the silicon substrate, provided in an embodiment of the present invention;

[0049] Figure 12 A cross-sectional schematic diagram of a micro-light-emitting diode mesa array after etching away the AlN buffer layer and AlGaN stress modulation layer, as provided in an embodiment of the present invention;

[0050] Figure 13 A cross-sectional schematic diagram of a micro-light-emitting diode mesa array after depositing an n-type transparent electrode layer and a transparent electrode bonding layer, provided in an embodiment of the present invention;

[0051] Figure 14This is a cross-sectional schematic diagram of a micro-light-emitting diode mesa array bonded to a transparent substrate according to an embodiment of the present invention;

[0052] Figure 15 This is a cross-sectional schematic diagram of a micro-light-emitting diode mesa array after the temporary substrate has been removed, as provided in an embodiment of the present invention.

[0053] Explanation of reference numerals in the attached figures:

[0054] 101-Pristine silicon substrate, 102-Silicon substrate mesa, 201-AlN buffer layer, 202-AlGaN stress modulation layer, 203-n-type GaN layer, 204-InGaN / GaN composite multiple quantum well layer, 205-p-type conductive layer, 301-Red photonic pixel region, 302-Green photonic pixel region, 303-Blue photonic pixel region, 401-p-type electrode layer, 601-High-resistivity region, 701-Temporary substrate, 801-Temporary bonding layer, 1001-n-type transparent electrode layer, 1002-Transparent electrode bonding layer, 1101-Transparent substrate. Detailed Implementation

[0055] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0056] The purpose of this invention is to provide a nitride full-color integrated micro light-emitting diode display chip and its fabrication method. The chip structure integrates red, green and blue primary color sub-pixels, which greatly reduces the technical difficulty of mass transfer in full-color display chips.

[0057] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0058] like Figure 1 and Figure 2 As shown, the structure of the nitride full-color integrated micro light-emitting diode display chip in this embodiment of the invention includes a transparent substrate 1101, a transparent electrode bonding layer 1002, and a mesa array composed of four columnar micro light-emitting diode mesas. The micro light-emitting diode mesa array is connected to the transparent substrate through the transparent electrode bonding layer.

[0059] like Figure 2 As shown, the mesa width of the miniature light-emitting diode is 50μm, and the mesa spacing is 80μm.

[0060] like Figure 2As shown, the micro-light-emitting diode mesa structure includes, from the transparent substrate and the transparent electrode bonding layer upwards, the following layers in sequence: an n-type transparent electrode layer 1001, an n-type GaN layer 203, a three-cycle InGaN / GaN composite multiple quantum well layer 204, a p-type conductive layer 205, and a p-type electrode layer 401.

[0061] Specifically, the tensile stress in the n-type GaN layer of the micro-LED mesa structure shows a distribution trend of high stress at the center of the mesa and low stress at the outer edge.

[0062] Furthermore, each cycle of the InGaN / GaN composite multiple quantum well layer in the micro-LED mesa structure includes one high-indium-content InGaN / GaN quantum well and two low-indium-content InGaN / GaN quantum wells. In the central region of the micro-LED mesa, the high-indium-content InGaN / GaN quantum well dominates light emission; in the outer region of the micro-LED mesa, the low-indium-content InGaN / GaN quantum wells dominate light emission.

[0063] Specifically, from the central region to the outer ring region of the micro-LED mesa, the indium composition of the InGaN potential well layer in the InGaN / GaN composite multi-quantum well layer shows a gradually decreasing distribution trend. Specifically, the indium composition of the InGaN potential well layer in the high-indium-content InGaN / GaN quantum well gradually decreases from 40% to 31%, while the indium composition of the InGaN potential well layer in the low-indium-content InGaN / GaN quantum well gradually decreases from 31% to 17%. Correspondingly, the emission wavelength of the high-indium-content InGaN / GaN quantum well gradually blue-shifts from 630 nm to 550 nm, while the emission wavelength of the low-indium-content InGaN / GaN quantum well gradually blue-shifts from 550 nm to 450 nm.

[0064] like Figure 3 As shown, on the micro LED platform, the annular region with a light emission center wavelength in the range of 610~630nm is defined as the red photonic pixel region 301, the annular region with a light emission center wavelength in the range of 510~530nm is defined as the green photonic pixel region 302, and the annular region with a light emission center wavelength in the range of 450~470nm is defined as the blue photonic pixel region 303.

[0065] Furthermore, the p-type conductive layer in the micro-LED mesa structure includes a p-type AlGaN electron blocking layer and a p-type GaN layer; such as Figure 2 and Figure 4 As shown, the p-type conductive layer between the red, green, and blue primary color sub-pixel regions is transformed into a high-resistivity layer 601 through ion implantation, thereby achieving device isolation between sub-pixels; while the p-type conductive layer above the red, green, and blue primary color sub-pixel regions is not subjected to ion implantation.

[0066] Specifically, in the micro-LED mesa structure, the p-type electrode layer is distributed in a ring shape, and the surface of the p-type conductive layer that has not undergone ion implantation treatment is located on the red, green, and blue primary color sub-pixels respectively.

[0067] like Figures 4 to 15 As shown, the method for fabricating the nitride full-color integrated micro light-emitting diode display chip of the present invention includes the following steps:

[0068] S1. Provide a raw silicon substrate 101 with a (111) crystal plane, a thickness of 1.5 mm and a diameter of 200 mm.

[0069] S2, such as Figure 4 As shown, the surface of the original silicon substrate 101 in step 1 is etched into an array of columnar or trapezoidal mesa 102 using photolithography and etching processes. The height of the mesa is 20 μm, the width of the mesa is 50 μm, and the spacing between the mesa is 80 μm.

[0070] S3, such as Figure 5 As shown, using a metal-organic chemical vapor deposition (MOCVD) apparatus, a 300 nm thick AlN buffer layer 201 and a 300 nm thick AlN buffer layer 201 are sequentially epitaxially grown on the silicon substrate mesa array prepared in step S2. 0.5 Ga 0.5 An n-type GaN mesa array is formed by an N-stress modulation layer 202 and a 2μm thick n-type GaN layer 203. Due to the stress release effect of the mesa sidewalls, the tensile stress distribution in the n-type GaN mesa shows a trend of high at the center and low at the outer edge.

[0071] S4. On the n-type GaN mesa array prepared in step S3, three cycles of InGaN / GaN composite multiple quantum well layers 204 are epitaxially formed. Each cycle of the InGaN / GaN composite multiple quantum well layer includes one high-indium-content InGaN / GaN quantum well and two low-indium-content InGaN / GaN quantum wells. Due to the stress distribution trend of the n-type GaN mesa formed in step S3, the indium atom lattice incorporation efficiency of the InGaN / GaN composite multiple quantum well layer gradually decreases from the center to the outer edge. The indium content gradually decreases from the center region of the mesa to the outer region, while the emission wavelength of the InGaN / GaN composite multiple quantum wells gradually blue-shifts from the center region to the outer region. In the center region of the mesa, the indium atom lattice incorporation efficiency is high, resulting in higher epitaxial quality of high-indium-content InGaN / GaN quantum wells, which dominate the emission. In the outer region of the mesa, the indium atom lattice incorporation efficiency is insufficient, leading to poor epitaxial quality of high-indium-content InGaN / GaN quantum wells, which dominate the emission.

[0072] S5. Based on step S4, continue to epitaxially grow a p-type conductive layer 205, including a p-type AlGaN electron blocking layer and a p-type GaN layer, to form a micro light-emitting diode mesa array.

[0073] S6. Optimize the height and width of the silicon substrate mesa in step S2, the aluminum composition and thickness of the AlGaN stress modulation layer in step S3, and the indium composition and thickness of the InGaN potential well layer of the high-indium-content and low-indium-content InGaN / GaN quantum wells in step S4, so that the emission wavelength of the high-indium-content InGaN / GaN quantum well gradually blue-shifts from 630nm to 550nm from the center region of the micro-LED mesa to the outer ring region, while the emission wavelength of the low-indium-content InGaN / GaN quantum well gradually blue-shifts from 550nm to 450nm.

[0074] S7. The emission wavelength distribution of the micro-LED mesa array formed in steps S1~S6 is tested by cathode fluorescence spectroscopy scanning, such as... Figure 6 As shown, the annular region with a light emission center wavelength in the range of 610~630nm is defined as the red photonic pixel region 301, the annular region with a light emission center wavelength in the range of 510~530nm is defined as the green photonic pixel region 302, and the annular region with a light emission center wavelength in the range of 450~470nm is defined as the blue photonic pixel region 303.

[0075] S8, such as Figure 7 and Figure 8 As shown, using photolithography, metal deposition, and lift-off processes, three ring-shaped Ni / Au metal stacks are deposited as p-type electrode layers 401 on the micro-LED mesa array prepared in steps S1-S6, covering the surface. Figure 6 The surface of the red, green, and blue sub-pixel regions shown.

[0076] S9, such as Figure 9 As shown, using the p-type electrode layer prepared in step S8 as a mask, Ar is performed. + Ion implantation process, Ar + The ion dose is 4 × 10 12 cm -2 With an energy of 40keV, the p-type conductive layer between the red, green, and blue primary color sub-pixels without a mask is transformed into a high-resistivity region 601, thereby achieving device isolation between the red, green, and blue sub-pixels.

[0077] S10, such as Figure 10 As shown, the micro-light-emitting diode mesa array prepared in step S9 is bonded to the temporary substrate 701.

[0078] S11, such as Figure 11As shown, the silicon substrate is removed by etching with KOH solution, leaving the micro-LED mesa array on a temporary substrate. The micro-LED mesa structure on the temporary substrate, from bottom to top, consists of a temporary bonding layer 801, a p-type electrode layer 401, a p-type conductive layer 205, an InGaN / GaN composite multiple quantum well layer 204, an n-type GaN layer 203, an AlGaN stress modulation layer 202, and an AlN buffer layer 201.

[0079] S12, such as Figure 12 As shown, photolithography and etching processes are used to remove the AlN buffer layer and AlGaN stress modulation layer in the micro light-emitting diode mesa structure in step S11, exposing the n-type GaN layer 203.

[0080] S13, such as Figure 13 As shown, in step S12, an ITO thin film is deposited on the exposed n-type GaN layer in the micro light-emitting diode mesa structure as an n-type transparent electrode layer 1001 and an Au metal layer is deposited as a transparent electrode bonding layer 1002.

[0081] S14, such as Figure 14 As shown, a micro-light-emitting diode mesa array with an n-type transparent electrode layer and a transparent electrode bonding layer deposited is bonded onto a transparent substrate 1101.

[0082] S15, such as Figure 15 As shown, the temporary substrate described in step S10 is removed.

[0083] S16. The micro-LED mesa array on the transparent substrate prepared in steps S1-S15 is cut into chips; each chip includes a mesa array composed of 4 micro-LED mesas, thus realizing the following... Figure 2 and 3 The nitride full-color integrated micro light-emitting diode display chip shown is shown.

[0084] The beneficial effects of this invention are as follows:

[0085] (1) The nitride full-color integrated micro light-emitting diode display chip disclosed in this invention integrates red, green and blue three primary color sub-pixels, which greatly reduces the difficulty of the mass transfer process of the full-color micro light-emitting diode display chip.

[0086] (2) The red, green and blue sub-pixels of the nitride full-color integrated micro light-emitting diode display chip disclosed in this invention are located on the same micro light-emitting diode platform, which has a high degree of integration, which is conducive to realizing high pixel density full-color micro light-emitting diode display and improving full-color mixing effect.

[0087] (3) The nitride full-color integrated micro light-emitting diode display chip disclosed in this invention has a vertical structure micro light-emitting diode mesa, which is beneficial to improving the current injection efficiency and photoelectric performance of the micro light-emitting diode device.

[0088] (4) The method for fabricating nitride full-color integrated micro light-emitting diode display chip disclosed in this invention can complete the fabrication of red, green and blue three primary color InGaN / GaN composite multiple quantum wells by performing only one epitaxial process, thereby simplifying the process flow.

[0089] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0090] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A full-color nitride integrated micro-LED display chip, characterized in that, The application relates to a transparent substrate, a transparent electrode bonding layer and a mesa array composed of single or several micro light emitting diode mesas. The micro light emitting diode mesa or the mesa array is connected with the transparent substrate through the transparent electrode bonding layer. The structure of the micro light emitting diode mesa comprises, in sequence from the transparent substrate and the transparent electrode bonding layer, an n-type transparent electrode layer, an n-type GaN layer, one or several periods of InGaN / GaN composite multi-quantum well layers, a p-type conductive layer and a p-type electrode layer. Each period of the InGaN / GaN composite multi-quantum well layer comprises several high-indium-content InGaN / GaN quantum wells and several low-indium-content InGaN / GaN quantum wells; the central region of the micro light emitting diode mesa is dominated by the high-indium-content InGaN / GaN quantum wells for light emission; and the outer ring region of the micro light emitting diode mesa is dominated by the low-indium-content InGaN / GaN quantum wells for light emission. From the central region to the outer ring region of the micro light emitting diode mesa, the indium component of the InGaN potential well layer in the InGaN / GaN composite multi-quantum well layer presents a gradually decreasing distribution trend; from the central region to the outer ring region of the micro light emitting diode mesa, the light emission wavelength of the high-indium-content InGaN / GaN quantum well gradually blue-shifts from 630 nm to 550 nm; and from the central region to the outer ring region of the micro light emitting diode mesa, the light emission wavelength of the low-indium-content InGaN / GaN quantum well gradually blue-shifts from 550 nm to 450 nm. The light emission wavelength range of the micro light emitting diode mesa covers the red, green and blue three primary color wave bands; the light emission regions corresponding to the red, green and blue three primary color wave bands in the micro light emitting diode mesa are distributed in a ring shape; the ring-shaped region with a central light emission wavelength range of 610 to 630 nm in the micro light emitting diode mesa is a red light sub-pixel region; the ring-shaped region with a central light emission wavelength range of 510 to 530 nm in the micro light emitting diode mesa is a green light sub-pixel region; and the ring-shaped region with a central light emission wavelength range of 450 to 470 nm in the micro light emitting diode mesa is a blue light sub-pixel region. The micro light emitting diode mesa is in a columnar or stepped mesa shape; the width of the micro light emitting diode mesa ranges from 100 nm to 100 mu m; and the mesa spacing of the micro light emitting diode mesa ranges from 100 nm to 100 mu m.

2. The full-color nitride micro-LED display chip according to claim 1, wherein, The n-type GaN layer presents a gradually decreasing tensile stress distribution trend from the mesa center to the outer ring.

3. The full-color nitride micro-LED display chip of claim 1, wherein the first, second, third, fourth, fifth, and sixth III-V semiconductor layers are grown on the substrate by metal-organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), or hydride vapor phase epitaxy (HVPE). The p-type conductive layer comprises a p-type AlGaN electron blocking layer and a p-type GaN layer.

4. The full-color nitride micro-LED display chip of claim 1, wherein, The p-type conductive layer located between the red light sub-pixel region, the green light sub-pixel region and the blue light sub-pixel region is converted into a high-resistance layer through ion implantation; and the p-type conductive layer located on the red light sub-pixel region, the green light sub-pixel region and the blue light sub-pixel region is not subjected to ion implantation treatment. The p-type electrode layer is in a ring shape.

5. A nitride full-color integrated micro light-emitting diode display chip according to claim 4, characterized in that, The p-type electrode layer is located on the surface of the p-type conductive layer which is not subjected to ion implantation treatment. ​ 6. A method for fabricating a full-color nitride micro-LED display chip, comprising the steps of: providing a substrate; forming a plurality of first micro-LEDs on the substrate; forming a plurality of second micro-LEDs on the substrate; and forming a plurality of third micro-LEDs on the substrate. The method is applied to the nitride full-color integrated micro light-emitting diode display chip in any one of claims 1 to 5, and the method comprises the following steps: S1, providing a raw silicon substrate with a (111) crystal surface; S2, using a photoetching and etching process to etch the surface of the raw silicon substrate in step S1 into a columnar or stepped silicon substrate mesa array; the height of the mesa in the silicon substrate mesa array ranges from 10 μm to 100 μm; the width of the silicon substrate mesa array ranges from 10 μm to 100 μm; and the spacing of the silicon substrate mesa array ranges from 10 μm to 100 μm; S3, using a metal organic chemical vapor deposition device to sequentially epitaxially form an AlN buffer layer, an AlGaN stress modulation layer and an n-type GaN layer on the silicon substrate mesa array prepared in step S2, to obtain an n-type GaN mesa array; the structure parameters of the AlGaN stress modulation layer are adjusted according to the stress release effect of the mesa sidewall, so that the n-type GaN mesa prepared in step S3 is in a tensile stress state with a distribution trend of high in the center and low in the outer ring; the structure of the AlGaN stress modulation layer comprises one or more of a uniform component AlGaN structure, a gradually changing component AlGaN structure, an AlN / AlGaN superlattice structure, an AlGaN / GaN superlattice structure and an AlN / GaN superlattice structure; S4, epitaxially forming one or several periods of InGaN / GaN composite multi-quantum well layers on the n-type GaN mesa array prepared in step S3; each period of the InGaN / GaN composite multi-quantum well layer comprises several high-indium-content InGaN / GaN quantum wells and several low-indium-content InGaN / GaN quantum wells; S5, epitaxially forming a p-type conductive layer on the InGaN / GaN composite multi-quantum well layer of step S4 to obtain a nitride micro light-emitting diode mesa array; the p-type conductive layer comprises a p-type AlGaN electron blocking layer and a p-type GaN layer; S6, according to the principle that tensile stress promotes the incorporation of indium atomic lattices, the morphology parameters of the silicon substrate mesa in step S2, the structure parameters of the AlGaN stress modulation layer in step S3 are optimized, the tensile stress distribution trend of the n-type GaN mesa in step S3 is regulated, so that the indium component of the InGaN potential well layer of the InGaN / GaN composite multi-quantum well layer prepared in step S4 gradually decreases from the center region to the outer ring region of the mesa; the epitaxial growth parameters of the InGaN / GaN composite multi-quantum well layer in step S4 are optimized, so that the light-emitting wavelength of the high-indium-content InGaN / GaN quantum well gradually blue-shifts from 630 nm to 550 nm, and the light-emitting wavelength of the low-indium-content InGaN / GaN quantum well gradually blue-shifts from 550 nm to 450 nm, from the center region to the outer ring region of the micro light-emitting diode mesa formed in steps S1 to S5; and the light-emitting wavelength of the micro light-emitting diode mesa formed in steps S1 to S5 covers the red, green and blue three primary color wave bands for display applications from the center region to the outer ring region of the mesa. S7, determining a red light sub-pixel region, a green light sub-pixel region and a blue light sub-pixel region; S8, using a photolithography, metal evaporation and stripping process, depositing a ring-shaped p-type electrode layer on the red light sub-pixel region, the green light sub-pixel region and the blue light sub-pixel region of the micro light emitting diode mesa prepared in steps S1-S6; S9, using the p-type electrode layer prepared in step S8 as a mask to perform an ion implantation process, converting the unmasked covering region between the red light sub-pixel region, the green light sub-pixel region and the blue light sub-pixel region into a high resistance layer; S10, bonding the micro light emitting diode mesa array prepared in step S9 on a temporary substrate; S11, using an alkaline etching liquid to remove the original silicon substrate, fixing the micro light emitting diode mesa array on the temporary substrate; S12, using a photolithography and etching process, removing the AlN buffer layer and the AlGaN stress modulation layer in the micro light emitting diode mesa in step S11; S13, using a photolithography, metal evaporation and stripping process, depositing an n-type transparent electrode layer and a transparent electrode bonding layer on the n-type GaN layer exposed in step S12; S14, bonding the micro light emitting diode mesa array on which the n-type transparent electrode layer and the transparent electrode bonding layer are deposited on a transparent substrate; S15, removing the temporary substrate in step S10; S16, cutting the micro light emitting diode mesa array on the transparent substrate prepared in steps S1-S15 into chips; each chip comprises: a single or several silicon substrate mesa arrays composed of the micro light emitting diode mesa.

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