Full-color Micro-LED device and preparation method thereof
By employing a strip-shaped semiconductor structure and a shared semiconductor layer connection in Micro-LED devices, the problems of transfer accuracy and efficiency in Micro-LED integration technology have been solved, enabling the fabrication of high-precision, low-misalignment-rate full-color Micro-LED devices suitable for commercial production.
Patent Information
- Application Number
- CN202511080196.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-04
- Publication Date
- 2025-12-19
AI Technical Summary
Existing Micro-LED integration technologies suffer from problems such as short lifespan of color conversion materials, low transfer accuracy, and low efficiency, making it difficult to achieve large-scale commercial production of high-performance Micro-LED displays.
Using a long strip semiconductor structure as the basic unit, three different colored light-emitting modules are distributed in parallel and alternately, connected by a shared semiconductor layer, and combined with precise bonding technology to achieve efficient transfer and reduce the transfer misalignment rate.
It has achieved high-precision, low-misalignment-rate fabrication of Micro-LED devices, improved transfer efficiency and yield, reduced costs, and is suitable for commercial production.
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Figure CN121174752A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of semiconductor light-emitting devices, in particular to a full-color Micro-LED device and a preparation method thereof BACKGROUND
[0002] Unlike conventional large-area LEDs used for lighting, the typical pixel (Micro-LED die) size of Micro-LED is usually less than 50 μm, and even up to 10 μm. Such a small size brings great challenges to the array layout and system integration of Micro-LED displays.
[0003] The current mainstream Micro-LED integration technology solutions mainly fall into two categories: one is the Micro-LED full-color display integration solution based on color conversion, the core bottleneck of which is that the color conversion material has a short light-emitting life; the other is the massive transfer solution targeting large-scale Micro-LED chips, which uses van der Waals force adhesion, laser transfer, and roller transfer as technical means, and also has the problems of low transfer precision and chip misplacement in the transfer process, resulting in low yield. Moreover, the existing transfer solutions have not reached the demand of commercial large-scale production in terms of cost and efficiency.
[0004] Therefore, the Micro-LED integration technology has become a key problem restricting the development of high-performance Micro-LED displays. How to reduce the cost of full-color Micro-LED device integration solutions while achieving high-precision, misplacement-free, and high-efficiency transfer is a current technical problem. SUMMARY
[0005] Therefore, the Micro-LED integration technology has become a key problem restricting the development of high-performance Micro-LED displays. How to reduce the cost of full-color Micro-LED device integration solutions while achieving high-precision, misplacement-free, and high-efficiency transfer is a current technical problem.
[0006] A first object of the present application is to provide a full-color Micro-LED device.
[0007] A second object of the present application is to provide a preparation method of a full-color Micro-LED device.
[0008] The first object of the present application is achieved in the following manner: The full-color Micro-LED device comprises a driving module and a plurality of light-emitting modules. The driving module comprises a driving substrate, a protective layer, and a first bonding metal layer disposed on the driving substrate; the first bonding metal layer is composed of a common annular N electrode and an array of P electrode units, and the protective layer is disposed on the driving substrate not covered by the first bonding metal layer. The light-emitting module comprises a plurality of long strip-shaped semiconductor structures arranged in parallel, the long strip-shaped semiconductor structure comprises a shared semiconductor layer and a plurality of semiconductor mesas arranged on the shared semiconductor layer; the semiconductor mesa is provided with a second bonding metal layer; the long strip-shaped semiconductor structure comprises semiconductor mesas at the head and tail ends and semiconductor mesas in the middle, and the semiconductor mesa in the middle is further provided with an ohmic mirror layer between the second bonding metal layer. The light-emitting module comprises three different color light-emitting modules, and the three different color light-emitting modules are connected to the driving module through the first bonding metal layer and the second bonding metal layer; the long strip-shaped semiconductor structures of the three different color light-emitting modules are arranged in parallel and are arranged alternately.
[0009] The full-color Micro-LED device provided by the application adopts a long strip-shaped semiconductor structure as a basic structural unit in the light-emitting module, and the long strip-shaped semiconductor structures of the three different color light-emitting modules are arranged in parallel and alternately, so that full color can be realized. The shared semiconductor layer is reserved on the long strip-shaped semiconductor structure, and a plurality of semiconductor mesas are arranged in an array on the shared semiconductor layer, so that the semiconductor mesas can be connected through the shared semiconductor layer while maintaining independence. The above structure ensures that each semiconductor mesa can be controlled independently as an independent pixel, and at the same time, due to the connection of the bottom of the mesa, the entire strip-shaped semiconductor structure of the light-emitting module is transferred at the same time in the transfer process, so that the semiconductor mesas on the strip-shaped semiconductor structure are transferred at the same time, and the position sequence is fixed, and the problem of horizontal misalignment of the semiconductor mesas caused by insufficient accuracy of the transfer equipment is avoided, thereby reducing the misalignment rate of the transfer.
[0010] As an optional scheme of the full-color Micro-LED device, the shared semiconductor layer is an N-type GaN layer; the second bonding metal layer on the semiconductor mesas at the head and tail ends of the long strip-shaped semiconductor structure is bonded with a shared annular N electrode; and the second bonding metal layer on the semiconductor mesas in the middle of the long strip-shaped semiconductor structure is bonded with a P electrode unit.
[0011] As an optional scheme of the full-color Micro-LED device, in one light-emitting module, the number of long strip-shaped semiconductor structures is 640, the long strip-shaped semiconductor structures are arranged in parallel at equal intervals in the horizontal direction, the width of the long strip-shaped semiconductor structure is 3-100 mu m, and the distance between the long strip-shaped semiconductor structures is more than 2 times the width of the long strip-shaped semiconductor structure.
[0012] As an optional scheme of the full-color Micro-LED device, in one long strip-shaped semiconductor structure, the number of semiconductor mesas is 1080, the size of the semiconductor mesa is 1-50 mu m, and the size of the semiconductor mesa is less than or equal to the width of the long strip-shaped semiconductor structure.
[0013] As an optional solution of the full-color Micro-LED device, the material of the first bonding metal layer and the second bonding metal layer is any one or a combination of multiple of Ni, Cr, Pt or Au.
[0014] As an optional solution of the full-color Micro-LED device, the material of the ohmic mirror layer is any one or a combination of multiple of Ni, Al, Pt or Ag.
[0015] The second object of the application is achieved in that: A preparation method of a full-color Micro-LED device comprises the following steps: S01, a protection layer is prepared on the upper surface of a driving substrate, and a hole opening process is performed on the surface of the protection layer to expose the electrode contact of the driving substrate; S02, a first bonding metal layer is prepared on the electrode contact of the driving substrate; S03, an epitaxial wafer of one color is prepared; the epitaxial wafer comprises a substrate and an epitaxial layer, and the epitaxial layer comprises a first semiconductor layer, an active layer and a second semiconductor layer which are sequentially stacked on the substrate; S04, a mask layer is prepared on the second semiconductor layer, mesa etching is performed on the epitaxial layer to obtain an array-distributed semiconductor mesa, and a patterned epitaxial structure is obtained; the first semiconductor layer is not etched off, and the continuous part of the first semiconductor layer serves as a shared semiconductor layer; S05, an ohmic mirror layer is prepared on the semiconductor mesa; S06, a partition etching process is performed on the patterned epitaxial structure to be etched into a parallel-distributed long strip-shaped semiconductor structure; the partition etching process etches and removes the shared semiconductor layer between the long strip-shaped semiconductor structures; S07, a second bonding metal layer is prepared on the ohmic mirror layer to complete the preparation of a Micro-LED chip array; S08, the Micro-LED chip array is bonded to the driving substrate; S09, the substrate is removed; S10, steps S03-S09 are repeated twice again, Micro-LED chip arrays of two other colors are bonded to the driving substrate and the substrates are removed, and the preparation of the full-color Micro-LED device is completed.
[0016] Compared with the pick-and-place technology of the single chip as a transfer unit in the mass transfer process, the number of chips on the strip-shaped semiconductor structure is larger, the single strip-shaped semiconductor structure is taken as a basic unit of the entire full-color Micro-LED array, the entire Micro-LED array, i.e. hundreds or thousands of units, can be directly transferred by the application, and the transfer efficiency and speed are greatly improved.
[0017] As an alternative of the preparation method of the application, in step S01, the material of the protection layer is MgO.
[0018] As an alternative of the preparation method of the application, in step S04, the depth of mesa etching is 0.9-2.0 μm, and the etching is to the first semiconductor layer.
[0019] As an alternative of the preparation method of the application, after step S10, a conductive material layer is prepared on the common semiconductor layer, and the material of the conductive material layer is AZO transparent conductive film.
[0020] Additional aspects and advantages of the application will be described in the following description, some of which will be apparent from the description and some will be learned by practice of the application. BRIEF DESCRIPTION OF DRAWINGS
[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be regarded as limiting the scope of the present application.
[0022] Figure 1 The figure is a cross-sectional structure schematic diagram of the protection layer opening on the driving substrate in the embodiment of the present application.
[0023] Figure 2 The figure is a cross-sectional structure schematic diagram of the protection layer opening in the embodiment of the present application.
[0024] Figure 3 The figure is a cross-sectional structure schematic diagram of the first bonding metal layer prepared on the driving substrate in the embodiment of the present application.
[0025] Figure 4 The figure is a cross-sectional structure schematic diagram of the epitaxial wafer in the embodiment of the present application.
[0026] Figure 5 The figure is a cross-sectional structure schematic diagram of the mask layer prepared on the epitaxial wafer in the embodiment of the present application.
[0027] Figure 6 The figure is a cross-sectional structure schematic diagram of the mesa etching and the preparation of the ohmic mirror layer in the embodiment of the present application.
[0028] Figure 7 The figure is a planar structure schematic diagram of the separation etching in the embodiment of the present application.
[0029] Figure 8 The figure is a cross-sectional structure schematic diagram of the Micro-LED chip array obtained after the preparation of the second bonding metal layer in the embodiment of the present application.
[0030] Figure 9 A planar structure schematic diagram after a Micro-LED chip array of one color is bonded to a driving substrate and the substrate is removed in the embodiment of the present application.
[0031] Figure 10 A cross-sectional structure schematic diagram after a Micro-LED chip array of one color is bonded to a driving substrate in the embodiment of the present application.
[0032] Figure 11 A cross-sectional structure schematic diagram of a full-color Micro-LED device prepared in the embodiment of the present application.
[0033] Figure 12 A planar structure schematic diagram of a full-color Micro-LED device prepared in the embodiment of the present application.
[0034] Figure 13 A cross-sectional structure schematic diagram of another full-color Micro-LED device prepared in the embodiment of the present application.
[0035] In the figure: 100-driving module, 101-driving substrate, 102-protection layer, 103-first bonding metal layer, 1031-shared annular N electrode, 1032-P electrode unit, 105-photoresist mask layer; 300-epitaxial wafer, 301-substrate, 302-first semiconductor layer, 303-active layer, 304-second semiconductor layer; 200-light emitting module, 201-second bonding metal layer, 202-ohmic mirror layer, 203-long strip-shaped semiconductor structure, 2031-semiconductor mesa, 2032-shared semiconductor layer; 2001-red light emitting module, 2002-green light emitting module, 2003-blue light emitting module; 2033-conductive material layer. DETAILED DESCRIPTION
[0036] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described below in a clear and complete manner with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.
[0037] The embodiments of the present application provide a full-color Micro-LED device, as shown in Figure 10 which includes a driving module 100 and a plurality of light emitting modules 200. The driving module 100 comprises a driving substrate 101, a protective layer 102 and a first bonding metal layer 103 arranged on the driving substrate; the first bonding metal layer 103 is composed of a common annular N electrode 1031 and an array of P electrode units 1032, and the protective layer 102 is arranged on the driving substrate 101 not covered by the first bonding metal layer 103; The light-emitting module 200 comprises a plurality of parallel long strip-shaped semiconductor structures 203, each of which comprises a common semiconductor layer 2032 and an array of semiconductor mesas 2031 arranged on the common semiconductor layer 2032; a second bonding metal layer 201 is arranged on each semiconductor mesa 2031; and an ohmic mirror layer 202 is arranged between the middle semiconductor mesas 2031 and the second bonding metal layer 201 of the long strip-shaped semiconductor structures. As shown in Figure 12 The light-emitting module 200 comprises three light-emitting modules 2001 / 2002 / 2003 of different colors, which are all bonded to the driving module 100 through the first bonding metal layer 103 and the second bonding metal layer 201; and the long strip-shaped semiconductor structures 203 of the three light-emitting modules 2001 / 2002 / 2003 of different colors are parallel and arranged alternately.
[0038] In some embodiments of the present application, the common semiconductor layer 2032 is an N-type GaN layer; the second bonding metal layer 201 on the semiconductor mesas 2031 at the first end and the last end of the long strip-shaped semiconductor structure 203 is bonded to the common annular N electrode 1031; and the second bonding metal layer 201 on the semiconductor mesas 2031 in the middle of the long strip-shaped semiconductor structure 203 is bonded to the P electrode units 1032. The semiconductor mesas 2031 in the middle can be independently controlled through the P electrode units, while sharing the common annular N electrode 1031.
[0039] In some embodiments of the present application, in one light-emitting module 200, the number of long strip-shaped semiconductor structures 203 is 640, the long strip-shaped semiconductor structures 203 are arranged in the horizontal direction at equal intervals, the width of the long strip-shaped semiconductor structure 203 is 3-100 μm, and the distance between the long strip-shaped semiconductor structures 203 is more than twice the width of the long strip-shaped semiconductor structure 203.
[0040] In some embodiments of the present application, in one long strip-shaped semiconductor structure 203, the number of semiconductor mesas 2031 is 1080, the size of the semiconductor mesa 2031 is 1-50 μm, and the size of the semiconductor mesa 2031 is less than or equal to the width of the long strip-shaped semiconductor structure 203. The purpose of making the size of the semiconductor mesa 2031 less than the width of the long strip-shaped semiconductor structure 203 is to ensure that the sizes of the structures match to prevent electric leakage.
[0041] In some embodiments of the present application, the material of the first bonding metal layer 103 and the second bonding metal layer 201 is any one or a combination of multiple of Ni, Cr, Pt or Au.
[0042] In some embodiments of the present application, the material of the ohmic mirror layer 202 is any one or a combination of multiple of Ni, Al, Pt or Ag. The ohmic mirror layer 202 uses a high reflectivity metal to improve light efficiency.
[0043] The embodiments of the present application also provide a preparation method of a full-color Micro-LED device, including the following steps: S01, a protection layer 102 is prepared on the upper surface of a driving substrate 101, and an opening process is performed on the surface of the protection layer 102 to expose the electrode contact of the driving substrate 101; S02, a first bonding metal layer 103 is prepared on the electrode contact of the driving substrate 101; S03, an epitaxial wafer 300 of one color is prepared; the epitaxial wafer 300 includes a substrate 301 and an epitaxial layer, and the epitaxial layer includes a first semiconductor layer 302, an active layer 303 and a second semiconductor layer 304 which are sequentially stacked on the substrate 301; S04, a mask layer is prepared on the second semiconductor layer 304, mesa etching is performed on the epitaxial layer to obtain an array-distributed semiconductor mesa 2031, and a patterned epitaxial structure is obtained; the first semiconductor layer 302 is not etched off, and the continuous part of the first semiconductor layer 302 remains as a shared semiconductor layer 2032; S05, an ohmic mirror layer 202 is prepared on the semiconductor mesa 2031; S06, a partition etching process is performed on the patterned epitaxial structure to be etched into a parallel-distributed long-strip-shaped semiconductor structure 203; the partition etching process etches and removes the shared semiconductor layer 2032 between the long-strip-shaped semiconductor structure 203; S07, a second bonding metal layer 201 is prepared on the ohmic mirror layer 202, and the preparation of a Micro-LED chip array is completed; S08, the Micro-LED chip array is bonded to the driving substrate 101; S09, the substrate 301 is removed; S10, steps S03-S09 are repeated twice again, and Micro-LED chip arrays of two other colors are bonded to the driving substrate 101 and the substrate 301 is removed, and the preparation of a full-color Micro-LED device is completed.
[0044] In some embodiments of this application, in step S01, the material of the protective layer 102 is MgO. As an inorganic mask, MgO has stable chemical properties and can withstand the corrosion of etching gases, protecting the driving substrate from damage during dry etching.
[0045] In some embodiments of this application, in step S04, the depth of mesa etching is 0.9μm-2.0μm, etching down to the first semiconductor layer 302.
[0046] In some embodiments of this application, after step S10, a conductive material layer 2033 is further prepared on the common semiconductor layer 2032. The material of the conductive material layer 2033 is an AZO transparent conductive film. The transparent conductive film can enhance the conductivity of the common semiconductor layer 2032 while minimizing surface light blocking.
[0047] In some embodiments of this application, in step S08, a precision flip-chip bonding machine is used for bonding, and hot-press bonding is used to achieve precise alignment, with a bonding temperature of 240℃-400℃.
[0048] In some embodiments of this application, the epitaxial wafer 300 is a gallium nitride-based epitaxial wafer on a silicon substrate; the process of removing the substrate 301 in step S09 is to use a wafer grinding machine to thin it and remove most of the silicon substrate, and then use a plasma etching method to remove the remaining silicon substrate. The combined gas used in the plasma dry etching is SF6 and C4F8. The fluorine radicals of SF6 can rapidly etch Si.
[0049] In some embodiments of this application, the driving substrate 101 may be subjected to peroxide treatment before repeated bonding processes, and the first bonding metal layer 103 may be bombarded with oxygen plasma to improve its surface activity and increase the reliability of the bonding process.
[0050] The following are some preferred embodiments of this application. Example 1
[0051] This embodiment provides a full-color Micro-LED device, such as... Figure 10 , 11 As shown, it includes a driving module 100 and three light-emitting modules 200 connected to the driving module 100. The light-emitting modules 200 are a red light-emitting module 2001, a green light-emitting module 2002, and a blue light-emitting module 2003.
[0052] The driving module 100 comprises a driving substrate 101, a protective layer 102 and a first bonding metal layer 103 arranged on the driving substrate. The first bonding metal layer 103 is composed of a common annular N electrode 1031 and an array of P electrode units 1032, and the protective layer 102 is arranged on the driving substrate 101 not covered by the first bonding metal layer 103. The first bonding metal layer 103 is made of Cr / Pt / Au laminated metal, with the thickness of Cr being 20 nm, the thickness of Pt being 80 nm, and the thickness of Au being 900 nm. The protective layer 102 is made of MgO.
[0053] The light-emitting module 200 comprises a plurality of parallel long strip-shaped semiconductor structures 203 and a second bonding metal layer 201 arranged on the long strip-shaped semiconductor structures 203. The long strip-shaped semiconductor structure 203 comprises a common semiconductor layer 2032 and a plurality of semiconductor mesas 2031 arranged on the common semiconductor layer 2032 in an array. The second bonding metal layer 201 is arranged on the semiconductor mesas 2031. In the long strip-shaped semiconductor structure 203, the area of the semiconductor mesas 2031 at the head and tail is 1.5-2 times the area of the semiconductor mesas 2031 in the middle, and an ohmic mirror layer 202 is arranged between the semiconductor mesas 2031 in the middle and the second bonding metal layer 201.
[0054] The long strip-shaped semiconductor structure 203 is made of gallium nitride-based material, and the common semiconductor layer 2032 is an N-type GaN layer. The second bonding metal layer 201 is also made of Cr / Pt / Au laminated metal, with the thickness of Cr being 20 nm, the thickness of Pt being 80 nm, and the thickness of Au being 400 nm. The ohmic mirror layer 202 is made of different materials for different colors of light, and the material of the ohmic mirror layer 202 in the red light-emitting module 2001 is Ni / Au laminated metal, with the thickness of Ni being 0.2 nm and the thickness of Au being 10 nm. The material of the ohmic mirror layer 202 in the green light-emitting module 2002 and the blue light-emitting module 2003 is metal Pt, with the thickness of Pt being 100 nm.
[0055] In one light-emitting module 200, the long strip-shaped semiconductor structures 203 are arranged in the horizontal direction with equal intervals. The width of the long strip-shaped semiconductor structure 203 is 3.3 μm, the size of the semiconductor mesa 2031 is 3 μm, and the distance between the long strip-shaped semiconductor structures 203 is 10.5 μm.
[0056] The red light-emitting module 2001, the green light-emitting module 2002 and the blue light-emitting module 2003 are all bonded to the driving module 100 through the first bonding metal layer 103 and the second bonding metal layer 201. The long strip-shaped semiconductor structures 203 of the red light-emitting module 2001, the green light-emitting module 2002 and the blue light-emitting module 2003 are parallel and arranged alternately.
[0057] The second bonding metal layer 201 on the semiconductor mesa 2031 of the head end and the tail end of the long strip-shaped semiconductor structure 203 is bonded with the common annular N electrode 1031; the second bonding metal layer 201 on the semiconductor mesa 2031 in the middle of the long strip-shaped semiconductor structure 203 is bonded with the P electrode unit 1032. After the common annular N electrode 1031 is bonded with the second bonding metal layer 201, it serves as the common N electrode on the side of the entire full-color Micro-LED device driving substrate. After the P electrode unit 1032 is bonded with the second bonding metal layer 201, it serves as a separate P electrode to control each semiconductor mesa 2031 (one semiconductor mesa 2031 is one pixel unit).
[0058] In one light-emitting module 200, the number of long strip-shaped semiconductor structures 203 is 640, and in one long strip-shaped semiconductor structure 203, the number of semiconductor mesas 2031 is 1080, so the number of pixels in the entire full-color Micro-LED device is 1080 x (640 x 3) pixel units. After the driving substrate 101 is powered on, the current will flow from the common annular N electrode 1031 through the common semiconductor layer 2032, which is an N-type GaN layer. The N-type GaN has certain conductivity due to silicon doping and can serve as a common N electrode on the side of the semiconductor mesa 2031. Embodiment 2
[0059] The preparation method of the full-color Micro-LED device provided in the embodiment will be described below, which specifically includes the following steps:
[0060] Step S01, a protective layer 102 is prepared on the upper surface of the driving substrate 101, and a hole opening process is performed on the surface of the protective layer 102 to expose the electrode contact of the driving substrate 101.
[0061] Specifically, first, the protective layer 102 is prepared on the upper surface of the driving substrate 101 by electron evaporation. The protective layer 102 is MgO with a thickness of 100 nm and an evaporation temperature of 150°C. After evaporation, the photoresist mask layer 105 in the hole opening window area is removed and the photoresist mask layer 105 in the non-hole opening area is retained by sequentially performing the steps of pre-baking, exposure, development and hardening by using a photoetch process, as shown in Figure 1 Subsequently, the protective layer 102 in the hole opening area and the passivation layer of the driving substrate 101 itself are etched and removed by a dry etching process, as shown in Figure 2 to expose the electrode contact of the driving substrate 101.
[0062] Step S02, a first bonding metal layer 103 is prepared on the electrode contact of the driving substrate 101.
[0063] Specifically, please refer to Figure 3 The first bonding metal layer 103 includes a common annular N electrode 1031 and an array of P electrode units 1032. The first bonding metal layer 103 is prepared on the driving substrate 101 by a conventional photolithography stripping metal process, and the first bonding metal layer 103 is connected with the electrode contacts of the driving substrate 101.
[0064] The common annular N electrode 1031 and the array of P electrode units 1032 are both Cr / Pt / Au laminated metal, the thickness of Cr is 20 nm, the thickness of Pt is 80 nm, and the thickness of Au is 900 nm.
[0065] In addition, after completing the photolithography process, before evaporating the first bonding metal layer 103, a peroxide treatment can be performed, and the oxygen plasma is used for cleaning to remove the photolithography residue that may not be developed completely, and the oxygen plasma treatment time is 5-10 minutes.
[0066] S03, prepare red, green and blue epitaxial wafers 300 respectively; the epitaxial wafer 300 includes a substrate 301 and an epitaxial layer, the epitaxial layer includes a first semiconductor layer 302, an active layer 303 and a second semiconductor layer 304 which are sequentially laminated on the substrate 301.
[0067] Specifically, as shown in Figure 4 The epitaxial wafer 300 is a silicon substrate gallium nitride-based epitaxial wafer, the substrate 301 is a silicon substrate, the first semiconductor layer 302 is N-type GaN, the active layer 303 is an InGaN / GaN multi-quantum well layer, and the second semiconductor layer 304 is P-type GaN. The three kinds of color epitaxial wafers 300 are subjected to process cleaning, first immersed in a mixed solution of concentrated sulfuric acid and hydrogen peroxide with a volume ratio of 3:1 for 5-15 minutes to remove organic impurities on the surface of the epitaxial wafer 300. Then ultrasonic in acetone for 2-5 minutes, ultrasonic in alcohol for 5-10 minutes, finally washed with deionized water for 5-10 minutes, and then dried in an oven.
[0068] S04, prepare a photoresist photoresist mask layer 105 on the second semiconductor layer 304 of the three kinds of color epitaxial wafers 300 respectively, and perform mesa etching on the epitaxial layer to obtain an array of semiconductor mesas 2031, and obtain a patterned epitaxial structure; the first semiconductor layer 302 is not cut off, and the continuous part of the first semiconductor layer 302 is reserved as a common semiconductor layer 2032.
[0069] Specifically, first coat the photoresist material on the entire surface of the second semiconductor layer 304, and sequentially perform the steps of pre-baking, exposure, development and hardening, only the photoresist mask layer 105 forming the array pattern of semiconductor mesas is reserved, and the remaining area is not covered with photoresist mask, as shown in Figure 5As shown. The photoresist is used as a mask to perform etching process to form an array of independent semiconductor mesas 2031, the number of semiconductor mesas 2031 is 1080x640, and the size of semiconductor mesa 2031 is 3μm. As shown. Figure 6 As shown. The etching depth of the etching process is 2.0μm, the second semiconductor layer 304 and the active layer 303 are completely etched off, and only part of the first semiconductor layer 302 is etched, and the remaining continuous part is used as a common semiconductor layer 2032, which is used as the N electrode of the Micro-LED device.
[0070] S05, respectively, on the semiconductor mesa 2031 of the three color epitaxial wafer 300 to prepare the ohmic mirror layer 202.
[0071] Specifically, the photoresist material is coated on the semiconductor mesa 2031, and the steps of pre-baking, exposure, development and hardening are sequentially performed. The photoresist is removed in the area where the ohmic mirror layer 202 is evaporated, and the photoresist is retained in other areas. The ohmic contact mirror layer 202 is evaporated by electron beam evaporation, and then stripped and removed. The structure is as shown. Figure 6 .
[0072] Because the ohmic mirror layer 202 of different materials has different reflectivity for red, green and blue light, the material of the ohmic mirror layer 202 prepared on the red epitaxial wafer 300 is Ni / Au laminated metal, the thickness of Ni is 0.2nm, and the thickness of Au is 10nm; The material of the ohmic mirror layer 202 prepared on the green and blue epitaxial wafer 300 is metal Pt, and the thickness of Pt is 100nm.
[0073] S06, respectively, on the three color patterned epitaxial structure to perform a separation etching process to form a parallel distributed long strip semiconductor structure 203; the separation etching process etches and removes the common semiconductor layer 2032 between the long strip semiconductor structure 203.
[0074] Specifically, the separation etching process first needs to evaporate the whole surface of the non-metallic inorganic mask on the patterned epitaxial structure, and then the photoresist mask is prepared by the photolithography process. Under the coverage of the double-layer mask, the common semiconductor layer 2032 between the remaining long strip semiconductor structure 203 is etched off, that is, etched to the end of the substrate 301, and finally the structure diagram of the long strip semiconductor structure 203 is as shown. Figure 7 The long strip semiconductor structure 203 is horizontally and laterally arranged at equal intervals, the number of long strip semiconductor structure 203 is 640, each long strip semiconductor structure 203 has 1080 semiconductor mesas 2031, the width of long strip semiconductor structure 203 is 3.3μm, and the distance between long strip semiconductor structure 203 is 7.6μm.
[0075] Preferably, the photoresist mask is patterned by 5312 positive photoresist provided by Suzhou Ruihong Electronic Chemicals Co., Ltd.
[0076] S07, a second bonding metal layer 201 is prepared on the ohmic mirror layer 202 of the long strip-shaped semiconductor structure 203 of the three colors, respectively, to complete the preparation of the Micro-LED chip array of the three colors.
[0077] Specifically, the process of preparing the second bonding metal layer 201 is the same as that of preparing the first bonding metal layer 103 on the driving substrate 101. After preparation, the Micro-LED chip array structure of the three colors is shown in Figure 8 and Figure 9 .
[0078] Preferably, on the patterned epitaxial surface with undulations, the material of the second bonding metal layer 103 is Cr / Pt / Au stacked metal with a total thickness of 600 nm, and the electron beam evaporation temperature is controlled at 130°C.
[0079] S08, the red Micro-LED chip array is bonded to the driving substrate 101.
[0080] Specifically, as shown in Figure 10 , the second bonding metal layer 201 of the red Micro-LED chip array is corresponded to the position of the first bonding metal layer 103 by using a precision bonding machine, and the two are electrically connected by using hot-press bonding.
[0081] Preferably, the hot-press bonding conditions are: bonding pressure 50 Kg, bonding temperature 350°C, and holding time 2700s.
[0082] S09, the substrate 301 is removed.
[0083] Specifically, a wafer grinding machine is used for thinning to remove most of the silicon material, and then a plasma etching method is used to remove the remaining silicon material. The combined gas used in the plasma dry etching is SF6 and C4F8. The thickness of the remaining silicon substrate 303 removed by the plasma etching method is 100-200μm.
[0084] S10, the driving substrate 101 is subjected to peroxide treatment, the first bonding metal layer 103 is bombarded by oxygen plasma, the green Micro-LED chip array is bonded to the driving substrate 101, and the substrate 301 is removed.
[0085] S11, the driving substrate 101 is subjected to peroxide treatment, the first bonding metal layer 103 is bombarded by oxygen plasma, the blue Micro-LED chip array is bonded to the driving substrate 101, and the substrate 301 is removed.
[0086] The preparation of the full-color Micro-LED device is completed, and the structure thereof is shown in Figure 11 The strip-shaped semiconductor structures 203 of different color light-emitting modules are arranged in the horizontal direction in the form of equal-interval transverse parallel arrangement according to the red, green and blue rule, as shown in Figure 12 The interval between the strip-shaped semiconductor structures 203 of red, green and blue colors is 1 μm. Embodiment 3
[0087] The full-color Micro-LED device preparation method provided in the embodiment is the same as that in Embodiment 2, and the difference lies in that, as shown in Figure 13 In the embodiment, the conductive material layer 2033 is prepared above the shared semiconductor layer 2032, the uniformity of the current spreading of the entire Micro-LED array is greatly increased, and the light-emitting effect of the full-color Micro-LED device is improved.
[0088] Specifically, the conductive material layer 2033 is prepared, after the preparation of the full-color Micro-LED device is completed, on the upper surface of the shared semiconductor layer 2032, and then the conductive material layer 2033 is prepared on the entire surface by using the magnetron sputtering method.
[0089] Preferably, the conductive material layer 2033 is an AZO transparent conductive film, and the thickness thereof is 100-500 nm. AZO stands for aluminum-doped zinc oxide.
[0090] The above embodiments are only used to further illustrate the full-color Micro-LED display device and the preparation method thereof, but the present application is not limited to the embodiments, and any simple modification, equivalent change and modification made according to the technical essence of the present application to the above embodiments all fall within the protection scope of the technical scheme of the present application.
Claims
1. A full-color Micro-LED device, characterized in that, Includes a driving module and several light-emitting modules; The driving module includes a driving substrate and a protective layer and a first bonding metal layer disposed on the driving substrate; The first bonding metal layer consists of a common annular N electrode and an array of distributed P electrode units, and the protective layer is disposed on the driving substrate not covered by the first bonding metal layer. The light-emitting module includes several parallel elongated semiconductor structures. Each elongated semiconductor structure includes a common semiconductor layer and semiconductor mesa arrays distributed on the common semiconductor layer. A second bonding metal layer is provided on each semiconductor mesa. Each elongated semiconductor structure includes semiconductor mesa at the beginning and end and a middle semiconductor mesa. An ohmic reflector layer is also provided between the middle semiconductor mesa and the second bonding metal layer. The light-emitting module includes three different colored light-emitting modules, all of which are bonded to the driving module through a first bonding metal layer and a second bonding metal layer; the elongated semiconductor structures of the three different colored light-emitting modules are parallel and alternately distributed.
2. The full-color Micro-LED device according to claim 1, characterized in that: The common semiconductor layer is an N-type GaN layer; the second bonding metal layer on the semiconductor mesa at the beginning and end of the long strip semiconductor structure is bonded to the common annular N electrode; The second bonding metal layer on the semiconductor mesa in the middle of the elongated semiconductor structure is bonded to the P electrode unit.
3. The full-color Micro-LED device according to claim 1, characterized in that: Within a light-emitting module, there are 640 elongated semiconductor structures arranged horizontally in parallel with equal spacing in the horizontal direction. The width of each elongated semiconductor structure is 3μm-100μm, and the distance between each elongated semiconductor structure is more than twice the width of the elongated semiconductor structure.
4. The full-color Micro-LED device according to claim 1, characterized in that: Within an elongated semiconductor structure, the number of semiconductor mesa is 1080, the size of the semiconductor mesa is 1μm-50μm, and the size of the semiconductor mesa is less than or equal to the width of the elongated semiconductor structure.
5. The full-color Micro-LED device according to claim 1, characterized in that: The materials of the first bonding metal layer and the second bonding metal layer are any one or a combination of Ni, Cr, Pt or Au.
6. The full-color Micro-LED device according to claim 1, characterized in that: The material of the ohmic reflector layer is any one or a combination of Ni, Al, Pt or Ag.
7. A method for fabricating a full-color Micro-LED device, comprising the following steps: S01. A protective layer is prepared on the upper surface of the driving substrate, and an opening process is performed on the surface of the protective layer to expose the electrode contacts of the driving substrate. S02, A first bonding metal layer is prepared on the electrode contacts of the driving substrate; S03. Prepare an epitaxial wafer of one color; the epitaxial wafer includes a substrate and an epitaxial layer, the epitaxial layer including a first semiconductor layer, an active layer and a second semiconductor layer sequentially stacked on the substrate; S04. A mask layer is prepared on the second semiconductor layer, and mesa etching is performed on the epitaxial layer to obtain an array of semiconductor mesas, resulting in a patterned epitaxial structure; the first semiconductor layer is not cut off, and the continuous portion of the first semiconductor layer is used as a common semiconductor layer. S05. An ohmic mirror layer is fabricated on the semiconductor mesa. S06. Perform an isolation etching process on the patterned epitaxial structure to etch parallel distributed elongated semiconductor structures; the isolation etching process removes the common semiconductor layer between the elongated semiconductor structures. S07. Prepare a second bonding metal layer on the ohmic reflector layer to complete the fabrication of the Micro-LED chip array; S08. Bond the Micro-LED chip array to the driving substrate; S09, Remove substrate; S10. Repeat steps S03-S09 twice more to bond the Micro-LED chip arrays of the other two colors to the driving substrate and remove the substrate to complete the fabrication of the full-color Micro-LED device.
8. The method for fabricating a full-color Micro-LED device according to claim 7, characterized in that: In step S01, the material of the protective layer is MgO.
9. The method for fabricating a full-color Micro-LED device according to claim 7, characterized in that: In step S04, the depth of mesa etching is 0.9μm-2.0μm, etching down to the first semiconductor layer.
10. The method for fabricating a full-color Micro-LED device according to claim 7, characterized in that: After step S10, a conductive material layer is prepared on the common semiconductor layer, wherein the material of the conductive material layer is an AZO transparent conductive film.