A microlens structure MicroLED and preparation method thereof

Abstract

The invention relates to the technical field of display chips, and discloses a microlens structure MicroLED and a preparation method thereof. The microlens structure MicroLED comprises a driving substrate, on which a plurality of light-emitting units arranged in a rectangular array are arranged, the light-emitting units comprise a bonding metal layer, the bottom of the bonding metal layer is connected to the driving substrate, an epitaxial layer is arranged above the bonding metal layer, the epitaxial layer comprises a P-type semiconductor layer, a multi-quantum well layer and an N-type semiconductor layer arranged in sequence, the bottom of the P-type semiconductor layer is connected to the bonding metal layer, the middle of the N-type semiconductor layer is etched into a lens structure, ions are implanted in the outer circle of the N-type semiconductor layer to form a barrier layer, a passivation layer is deposited on the outer wall of the light-emitting unit, a light outlet is opened in the middle of the passivation layer corresponding to the N-type semiconductor layer, an ITO layer is deposited on the outer wall of the passivation layer, an N-electrode layer is deposited on the outer wall of the ITO layer, the N-type semiconductor layer is electrically connected to the N-electrode layer through the ITO layer, and the invention reduces the side wall damage caused by etching by ion implantation and microstructuring of the N-type semiconductor layer, and improves the collimation and focusing properties of light.

Description

Technical Field

[0001] The present invention belongs to the technical field of display chips, and in particular relates to a microlens structure MicroLED and a preparation method thereof. Background Art

[0002] The full name of Micro LED is Micro Light Emitting Diode, which is also called micro-light-emitting diode in Chinese, and can also be written as μLED. It generally refers to the technology of using LED light-emitting units with a size of 1~60um to form a display array. Its size is equivalent to 1 / 10 of a human hair. It has the characteristics of no need for backlight, high photoelectric conversion efficiency, and response time at the nanosecond level. It is to make LED thin-film, miniaturized and arrayed, so that its volume is only 1% of the size of mainstream LED. Color conversion technology is to use ultraviolet or blue light to excite the red and green quantum dot fluorescent materials coated on the Micro-LED chip to achieve high-resolution and high-efficiency full-color display technology. It has the characteristics of low technical threshold, low cost, and easy industrialization, and has received widespread attention.

[0003] Micro LED display panels generally include multiple LED pixels (i.e. light-emitting units). Traditional Micro LEDs obtain multiple completely isolated functional pixels by etching away continuous functional epitaxial layers. However, there are structural problems with the side light emission of pixels, such as light leakage / side structural defects, and serious light crosstalk between adjacent pixels. As the pixel size continues to shrink, this problem becomes more serious. Summary of the invention

[0004] In order to solve the deficiencies mentioned in the above background technology, the purpose of the present invention is to provide a microlens structure MicroLED and a preparation method thereof, which reduces the side wall damage caused by etching through ion implantation and microstructuring of the N-type semiconductor layer, while improving the collimation and focusing of light.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A microlens structure MicroLED includes a driving substrate, on which a plurality of light-emitting units arranged in a rectangular array are provided, the light-emitting units include a bonding metal layer, the bottom of the bonding metal layer is connected to the driving substrate, an epitaxial layer is provided above the bonding metal layer, the epitaxial layer includes a P-type semiconductor layer, a multi-quantum well layer and an N-type semiconductor layer arranged in sequence, the bottom of the P-type semiconductor layer is connected to the bonding metal layer, the middle of the N-type semiconductor layer is etched into a lens structure, ions are implanted in the outer circle of the N-type semiconductor layer to form a barrier layer, a passivation layer is deposited on the outer wall of the light-emitting unit, a light outlet is opened in the middle of the passivation layer corresponding to the N-type semiconductor layer, an ITO layer is deposited on the outer wall of the passivation layer, an N-electrode layer is deposited on the outer wall of the ITO layer, and the N-type semiconductor layer is electrically connected to the N-electrode layer through the ITO layer.

[0007] Further preferably, the driving substrate is a silicon-based CMOS backplane or a TFT field effect transistor display substrate, and the driving substrate has metal contacts connected to the internal circuit.

[0008] Further preferably, the bonding metal layer is a multilayer structure formed by a composite of metal films or non-metal films, and both the metal films and the non-metal films are conductors.

[0009] Further preferably, the passivation layer material is SiO2, Al2O3, SiN, polyimide or SU-8 photoresist, the projected area of ​​the passivation layer on the driving substrate is larger than the area of ​​the epitaxial layer, the passivation layer height is lower than the N-type semiconductor layer height, and the passivation layer coverage height is adjusted according to the optical design light output angle.

[0010] Further preferably, the ITO layer fully covers the epitaxial layer, the N-electrode layer is provided with a light outlet at the lens structure in the middle of the N-type semiconductor layer, and the top surface of the lens structure in the middle of the N-type semiconductor layer is higher than the N-electrode layer.

[0011] Further preferably, the ions implanted into the barrier layer are one or more of hydrogen, magnesium, nitrogen, fluorine, oxygen, helium, silicon and argon ions.

[0012] Further preferably, the material of the N-electrode layer is one or more of metals selected from Cr, Ti, Pt, Au, Al, Cu, Ge and Ni.

[0013] A method for preparing a micro-lens structure MicroLED, comprising the following steps:

[0014] S1. coating a first metal layer of a multilayer structure on the surface of the epitaxial layer of the epitaxial wafer by vacuum evaporation coating, vacuum sputtering coating or vacuum ion coating;

[0015] S2, coating a second metal layer on the surface of the driving substrate by vacuum evaporation coating, vacuum sputtering coating or vacuum ion coating;

[0016] S3, bonding the coated epitaxial wafer and the driving substrate by flip-chip bonding, bonding the first metal layer and the second metal layer to obtain a bonding metal layer, forming a good ohmic contact, and removing the epitaxial wafer substrate and the buffer layer;

[0017] S4, microstructuring the N-type semiconductor layer by dry or wet etching to form a lens structure, wherein the etching thickness is less than the thickness of the N-type semiconductor layer;

[0018] S5, implanting ions into the N-type semiconductor layer in the outer ring of the microstructure to form a barrier layer by an ion implantation method;

[0019] S6, etching and grooving the epitaxial layer by dry or wet etching, and patterning the bonding metal layer by IBE etching to form an independent light-emitting unit;

[0020] S7, depositing a passivation layer by PECVD and patterning it by IBE, etching away the passivation layer above the lens structure of the N-type semiconductor layer to expose the light-emitting surface of the LED;

[0021] S8, depositing an ITO layer on the surface of the passivation layer by vacuum evaporation coating, vacuum sputtering coating or vacuum ion coating, so that the ITO layer fully covers the epitaxial layer;

[0022] S9, depositing an N electrode layer on the surface of the ITO layer by photolithography, evaporation or lift-off, and completing the N electrode patterning preparation.

[0023] Beneficial effects of the present invention:

[0024] The present invention reduces the side wall damage caused by etching by ion implantation and N-type semiconductor layer microstructuring. At the same time, the light emitting surface of the N-type semiconductor is a lens structure, which can refract the scattered light to the middle and improve the collimation and focusing of the light. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] 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, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 is a schematic structural diagram of a micro-lens structure MicroLED in Embodiment 1 of the present invention;

[0027] Figure 2 It is a process flow diagram of step S1 of the present invention;

[0028] Figure 3 It is a process flow diagram of step S2 of the present invention;

[0029] Figure 4 It is a process flow diagram of step S3 of the present invention;

[0030] Figure 5 is a schematic diagram of the process flow of step S4 of the present invention;

[0031] Figure 6 It is a process flow diagram of step S5 of the present invention;

[0032] Figure 7 It is a process flow diagram of step S6 of the present invention;

[0033] Figure 8 is a schematic diagram of the process flow of step S7 of the present invention;

[0034] Fig. 9 It is a process flow diagram of step S8 of the present invention;

[0035] Fig.10 It is a schematic diagram of the process flow of step S9 of the present invention.

[0036] In the figure: 1-epitaxial wafer, 2-substrate, 3-buffer layer, 4-epitaxial layer, 5-N-type semiconductor layer, 6-multi-quantum well layer, 7-P-type semiconductor layer, 8-first metal layer, 9-driving substrate, 10-second metal layer, 11-bonding metal layer, 12-barrier layer, 13-passivation layer, 14-ITO layer, 15-N electrode layer. DETAILED DESCRIPTION

[0037] The following will be combined with the embodiments of the present invention 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.

[0038] like Figure 1As shown, the present invention provides a microlens structure MicroLED, including a driving substrate 9, on which a plurality of light-emitting units arranged in a rectangular array are provided, the light-emitting units include a bonding metal layer 11, the bottom of the bonding metal layer 11 is connected to the driving substrate 9, an epitaxial layer 4 is provided above the bonding metal layer 11, the epitaxial layer 4 includes a P-type semiconductor layer 7, a multi-quantum well layer 6 and an N-type semiconductor layer 5 arranged in sequence, the bottom of the P-type semiconductor layer 7 is connected to the bonding metal layer 11, the middle of the N-type semiconductor layer 5 is etched into a lens structure, ions are implanted in the outer circle of the N-type semiconductor layer 5 to form a barrier layer 12, a passivation layer 13 is deposited on the outer wall of the light-emitting unit, a light outlet is opened in the middle of the passivation layer 13 corresponding to the N-type semiconductor layer 5, an ITO layer 14 is deposited on the outer wall of the passivation layer 13, an N-electrode layer 15 is deposited on the outer wall of the ITO layer 14, and the N-type semiconductor layer 5 is electrically connected to the N-electrode layer 15 through the ITO layer 14.

[0039] In some embodiments, the driving substrate 9 is a silicon-based CMOS backplane or a TFT field effect transistor display substrate, and the driving substrate 9 has metal contacts connected to the internal circuit.

[0040] In some embodiments, the bonding metal layer 11 is a multilayer structure composed of metal films or non-metallic films, and both the metal films and the non-metallic films are conductors, for example: metals such as Cr, Ni, Au, Ag, Sn, Ti, Pt, Pb or conductive oxides such as ITO.

[0041] In some embodiments, the material of the passivation layer 13 is SiO2, Al2O3, SiN, polyimide or SU-8 photoresist, or other photo-patternable polymers. The projected area of ​​the passivation layer 13 on the driving substrate 9 is larger than the area of ​​the epitaxial layer 4. The height of the passivation layer 13 is lower than the height of the N-type semiconductor layer 5. The coverage height of the passivation layer 13 is adjusted according to the optical design light output angle.

[0042] In some embodiments, the ITO layer 14 fully covers the epitaxial layer 4 , and the N-electrode layer 15 has a light outlet at the lens structure in the middle of the N-type semiconductor layer 5 , and the top surface of the lens structure in the middle of the N-type semiconductor layer 5 is higher than the N-electrode layer 15 .

[0043] In some embodiments, the ions implanted into the barrier layer 12 are one or more of hydrogen, magnesium, nitrogen, fluorine, oxygen, helium, silicon and argon ions.

[0044] In some embodiments, the material of the N-electrode layer 15 is one or more of metals selected from the group consisting of Cr, Ti, Pt, Au, Al, Cu, Ge, and Ni.

[0045] Figures 2 to 9 The schematic diagram of the structure of the above-mentioned microlens structure MicroLED at different stages in the preparation process is illustrated, and the preparation method thereof specifically includes the following steps:

[0046] S1, coating a first metal layer 8 of a multilayer structure on the surface of the epitaxial layer 4 of the epitaxial wafer 1 by vacuum evaporation coating, vacuum sputtering coating or vacuum ion coating;

[0047] S2, coating a second metal layer 10 on the surface of the driving substrate 9 by vacuum evaporation coating, vacuum sputtering coating or vacuum ion coating;

[0048] S3, bonding the coated epitaxial wafer 1 and the driving substrate 9 by flip-chip bonding, bonding the first metal layer 8 and the second metal layer 10 to obtain a bonding metal layer 11, forming a good ohmic contact, and removing the epitaxial wafer 1 substrate 2 and the buffer layer 3;

[0049] S4, microstructuring the N-type semiconductor layer 5 by dry or wet etching to form a lens structure, wherein the etching thickness is less than the thickness of the N-type semiconductor layer 5;

[0050] S5, implanting ions into the N-type semiconductor layer 5 in the outer ring of the microstructure to form a barrier layer 12 by an ion implantation method;

[0051] S6, etching and grooving the epitaxial layer 4 by dry or wet etching, and patterning the bonding metal layer 11 by IBE etching to form an independent light-emitting unit;

[0052] S7, depositing the passivation layer 13 by PECVD and patterning it by IBE, etching away the passivation layer 13 above the lens structure of the N-type semiconductor layer 5 to expose the light emitting surface of the LED;

[0053] S8, depositing an ITO layer 14 on the surface of the passivation layer 13 by vacuum evaporation coating, vacuum sputtering coating or vacuum ion coating, so that the ITO layer 14 fully covers the epitaxial layer 4. ITO has good conductivity and transparency, and combined with the N electrode layer 15, it can provide better conductivity and reduce resistivity;

[0054] S9, depositing an N-electrode layer 15 on the surface of the ITO layer by photolithography, evaporation or lift-off, and completing the N-electrode patterning preparation.

[0055] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0056] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A micro-lens structure MicroLED, characterized in that: A drive substrate is provided on the drive substrate, and a plurality of light-emitting units arranged in a rectangular array are provided on the drive substrate, and the light-emitting units include a bonding metal layer, and the bottom of the bonding metal layer is connected to the driving substrate, and an epitaxial layer is provided above the bonding metal layer, and the epitaxial layer includes a P-type semiconductor layer, a multi-quantum well layer and an N-type semiconductor layer arranged in sequence, and the bottom of the P-type semiconductor layer is connected to the bonding metal layer, and the middle of the N-type semiconductor layer is etched into a lens structure, and ions are implanted in the outer circle of the N-type semiconductor layer to form a barrier layer, and a passivation layer is deposited on the outer wall of the light-emitting unit, and a light outlet is opened in the middle of the passivation layer corresponding to the N-type semiconductor layer, and an ITO layer is deposited on the outer wall of the passivation layer, and an N-electrode layer is deposited on the outer wall of the ITO layer, and the N-type semiconductor layer is electrically connected to the N-electrode layer through the ITO layer; The method for preparing a micro-lens structure MicroLED comprises the following steps: S1. coating a first metal layer of a multilayer structure on the surface of the epitaxial layer of the epitaxial wafer by vacuum evaporation coating, vacuum sputtering coating or vacuum ion coating; S2, coating a second metal layer on the surface of the driving substrate by vacuum evaporation coating, vacuum sputtering coating or vacuum ion coating; S3, bonding the coated epitaxial wafer and the driving substrate by flip-chip bonding, bonding the first metal layer and the second metal layer to obtain a bonding metal layer, forming a good ohmic contact, and removing the epitaxial wafer substrate and the buffer layer; S4, microstructuring the N-type semiconductor layer by dry or wet etching to form a lens structure, wherein the etching thickness is less than the thickness of the N-type semiconductor layer; S5, implanting ions into the N-type semiconductor layer in the outer ring of the microstructure to form a barrier layer by an ion implantation method; S6, etching and grooving the epitaxial layer by dry or wet etching, and patterning the bonding metal layer by IBE etching to form an independent light-emitting unit; S7, depositing a passivation layer by PECVD and patterning it by IBE, etching away the passivation layer above the lens structure of the N-type semiconductor layer to expose the light-emitting surface of the LED; S8, depositing an ITO layer on the surface of the passivation layer by vacuum evaporation coating, vacuum sputtering coating or vacuum ion coating, so that the ITO layer fully covers the epitaxial layer; S9, depositing an N electrode layer on the surface of the ITO layer by photolithography, evaporation or lift-off, and completing the N electrode patterning preparation.

2. The micro-lens structure MicroLED according to claim 1, characterized in that: The driving substrate is a silicon-based CMOS backplane or a TFT field effect tube display substrate, and the driving substrate has metal contacts connected to the internal circuit.

3. The micro-lens structure MicroLED according to claim 1, characterized in that: The bonding metal layer is a multilayer structure formed by a composite of metal films or non-metal films, and both the metal films and the non-metal films are conductors.

4. The micro-lens structure MicroLED according to claim 1, characterized in that: The passivation layer material is SiO2, Al2O3, SiN, polyimide or SU-8 photoresist. The projected area of ​​the passivation layer on the drive substrate is larger than the area of ​​the epitaxial layer. The height of the passivation layer is lower than the height of the N-type semiconductor layer. The passivation layer coverage height is adjusted according to the optical design light output angle.

5. The micro-lens structure MicroLED according to claim 1, characterized in that: The ITO layer fully covers the epitaxial layer, and the N-electrode layer is provided with a light outlet at the lens structure in the middle of the N-type semiconductor layer. The top surface of the lens structure in the middle of the N-type semiconductor layer is higher than the N-electrode layer.

6. The micro-lens structure MicroLED according to claim 1, characterized in that: The ions implanted into the barrier layer are one or more of hydrogen, magnesium, nitrogen, fluorine, oxygen, helium, silicon and argon ions.

7. The micro-lens structure MicroLED according to claim 1, characterized in that: The N electrode layer material is one or more of metals selected from Cr, Ti, Pt, Au, Al, Cu, Ge and Ni.

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